WO2014202525A1

WO2014202525A1 - Device and method for transforming a tube

Info

Publication number: WO2014202525A1
Application number: PCT/EP2014/062555
Authority: WO
Inventors: Hubertus Russert
Original assignee: Schott Ag
Priority date: 2013-06-20
Filing date: 2014-06-16
Publication date: 2014-12-24
Also published as: DE102013211725A1

Abstract

The invention relates to a device for transforming a tube (11), in particular a glass tube and a capillary tube, in one transforming step (66), wherein the tube (11) has one or two open ends (24, 26), comprising a holding arrangement (12) for holding and fixing the tube (11), a heating tube (38) which surrounds the tube (11) in an annular manner and by which the tube (11) can be heated, a gas source (34) for providing a gas stream, and a connecting piece (28) communicating with the gas source (34) for introduction of the gas stream into the tube (11) via one of the open ends (24, 26). The invention further relates to a method and to a computer program for transforming the tube (11) and to the tube (11) per se.

Description

Apparatus and method for forming

a pipe

description

The present invention relates to a device for forming a tube,

in particular a glass tube and a capillary tube, in one

Forming section, wherein the tube has one or two open ends. Furthermore, the invention relates to a method for forming a tube, in particular a tube and a capillary tube and a computer program for operating a control unit, with which the device can be controlled. Moreover, the invention also relates to the inventively formed tubes, especially glass tubes and the capillary tubes. When reference is made to tubes in the following description, glass tubes, and in particular capillary tubes, are used

alike meant. In capillary tubes, the problems associated with the

To be solved invention to a particularly great extent, as will be described in more detail below.

The tubes, which are formed by means of the device and the method according to the invention, form the semifinished product, in particular for pipe sections used in the laboratory or in industrial production. The tubes may for example consist of plastic or glass or include these substances. The generic tubes are used when a liquid, which may also contain particles, must be conducted in a well-defined manner, for example in analytical chemistry. The general trend in detection tests of almost all kinds is that,

Keep sample and reagent volumes as low as possible, which makes the detection tests cheaper and more efficient. Capillary tubes are particularly suitable for this purpose. Some detection tests rely on mixing the sample and reagent volumes in a reaction space where precipitation occurs depending on the presence of a property of interest in the sample. The precipitation is the qualitative one

Proof that the sample has this property. However, over the Amount of precipitate formed, a statement can also be made as to the strength of the property. If one leads the precipitation of

Reaction space in a tube, so the level can be used for a quantitative detection. In particular, if you have a capillary tube for

Level measurement used, it is necessary to provide the capillary tube with a funnel-shaped portion or a radial extension to the

To be able to introduce precipitation from the reaction space into the capillary tube. The smaller the sample and reagent volume, the more accurate the radial extension must be made. Unevenness in the surface and deviations from the

Rotation symmetry and in the area of the extension can ensure that a certain amount of precipitation gets stuck in the radial extension and / or that the measured level does not correspond to reality. Consequently, the precision of the manufacture of the radial extension, in particular of a capillary tube, is of decisive importance for the significance of the capillary tube

carried out proof tests. But in other applications, where a defined volume is to be introduced into the tube, the precision of the radial

Extension in terms of rotational symmetry and the surface condition of high importance. In the glass industry, the radial expansion of a tube can be made in the following manner: The tube is fixed to two fixing sections and then approximately midway between the two fixing sections with a gas burner in

Heated forming section. The tube softens at the point where the capillary tube is heated and can be radially expanded or expanded by blowing in air to form a bubble. This process is well known in glassblowing. After the bubble has reached the desired size, it is allowed to cool the capillary tube and separates it in the area of the maximum diameter of the bubble, for example by scribing, so that two capillary tubes each with a radial extension arise. From the semifinished product thus arise two isolated components.

The US 5,112,376 shows a device with which a glass tube by means of a

Ring burner heated and radially expanded by compressed air. The radial Expansion is limited by a shaped body with a central bore, so that the glass tube in the expanded area has a defined outer diameter.

EP 0 992 460 A2 shows a device with which a glass tube can be heated and changed by means of a force applicator in its radial extent. Here, the force applicator may comprise a roller or a nozzle, whereby a radially directed to the longitudinal axis of the glass tube force is applied to the outer surface of the glass tube. DE 195 27 794 A1 discloses a method and an apparatus for producing optical elements in which a closed glass tube is heated and by generating a pressure difference between the pressure in the glass tube and the

Ambient pressure causes a radial expansion. The radial expansion is limited by templates.

In all cases, a force is applied to the outer surface of the glass tube, whereby inevitably form irregular prints and bumps on the outer surface of the glass tube. Particularly in the case of capillary tubes with a very small wall thickness, the impressions and unevenness are also transferred to the inner surface, so that they are meaningful for performing

Detection tests necessary rotational symmetry and precision of

Surface texture is not given.

The gas burner used for heating can not uniformly heat the capillary tube over the circumference. Nevertheless, a rotationally symmetric

To achieve heating, the tube is rotated during the heating around the longitudinal axis. For this purpose, the tube must be rotated on both sides of the Umformabschnitts at exactly the same rotational speed. Even small differences in the number of revolutions lead to the fact that the bubble does not form rotationally symmetrical and has a so-called twist. In the area of the twist, spiral depressions form so that the inner surface of the bubble is not flat and some of the precipitate may get caught on the surface of the extension. The twist and the surface properties in the area of the extension known capillary tubes mean that the above-mentioned detection tests can not be performed with the necessary accuracy, as already stated above. The object of the present invention is therefore to provide an apparatus and a method with which a pipe, and in particular a pipe and a

Capillary tubes can be made with an extension that has an im

Compared to known pipes have a significantly reduced twist and a smoother surface.

The problem is solved by a device according to claims 1 and 2; Further preferred embodiments are subject of the dependent claims.

The device according to the invention comprises a holding device for holding and fixing the tube, a heating tube which surrounds the tube in an annular manner and with which the tube can be heated, a gas source for providing a gas flow, and a connection piece communicating with the gas source for introducing the gas flow into the tube via one of the open ends, whereby a radial expansion of the desired dimensions can be formed in the forming section by free forming. Whenever a tube is mentioned below, the relevant ones are related

Versions also on a glass tube and a capillary tube. Due to the fact that the tube is surrounded annularly by the heating tube, the tube can be heated rotationally symmetrically in the deformation section without the tube having to be rotated about the longitudinal axis. It is not necessary that the heating tube is formed closed; Rather, the term "annular" should also be understood to mean a segmented heating tube which, for example, consists of two or more annular sectors. It can also be a certain distance between the

adjacent sectors remain as long as a rotationally symmetrical heating of the tube is given. A forming section is to be understood as meaning the section of the tube which expands measurable radially on the outside of the heating. The radial extension gives the tube in the forming section the shape of a bubble. This alone can significantly reduce the twist of the bladder so that the resulting enlargement is significantly more rotationally symmetric and has a more level interior surface which increases the quality of the test results, especially in analytical chemistry applications.

Furthermore, it is possible by the use of the annular heating tube to set a reproducible, known temperature profile along the longitudinal axis of the tube, so not only a temporally, but also a locally changing temperature. This makes it possible to change the shape and dimensions of the

to affect the resulting radial expansion, so that the radial

Extension relatively slowly along the longitudinal axis expands radially and large slopes are avoided. As a result, dead spaces and turbulence are prevented, which can accumulate the precipitate resulting from detection tests on the inner surface, resulting in a falsification of the measurement result. If the tube is expanded radially in the forming section, the wall thickness of the tube in the forming section also changes. Genereil can be said that the wall or material thickness decreases, the more the bubble expands radially. Empirical measurements have shown that the same geometrical conditions in the forming section and in particular the same wall thicknesses set when the tube is heated with the same temperature profile. This is an important one

Awareness, in that it is thereby possible to close from the outer diameter to the inner diameter, which is for the regulation of the process, as will be explained later, important.

Furthermore, the gas source can be subjected to a pressure which leads to a bubble of the desired size in a forming process. By varying the pressure and the size of the bubble is changed, making this device particularly suitable for custom-made. It is not necessary to heat the pipe several times. On the one hand, this accelerates the forming or manufacturing process and also reduces the formation of a twist within the bladder, since the tube is thermally less heavily loaded in the forming section. Depending on the size of the pipe, the second open end, over which no gas stream is introduced, must not be closed, which further simplifies the forming or manufacturing process. The connector is designed so that it allows quick connection to existing pressure systems such as compressed air lines, etc. Under a free forming should be understood that the tube in the

Forming section expanded radially only by the pressure prevailing in the tube. In this case, no molds are to be used, which come into contact with the tube and influence the shape and dimensions of the bladder. It is therefore a non-contact forming, wherein the shape of the bladder in addition to the pressure only on the temperature and the temperature profile, which are provided by the heating tube, is changeable. Due to the fact that the tube does not come into contact with a forming tool during forming, there are no bumps or marks on the surfaces of the tube, so that the surfaces are very smooth, which is why the tubes produced with the device according to the invention are particularly suitable for use in detection tests are.

The object is further achieved by means for forming a closed tube, in particular a glass tube and a capillary tube, in one

Forming section, wherein the closed tube a first and a second

closed end and is subjected to an atmospheric pressure, comprising a holding means for holding and fixing the closed tube, and heating tube, which surrounds the closed tube annular and with which the closed tube is heated when the tube is inserted into the holding device, whereby in Forming section by free forming a radial extension with the desired dimensions is malleable, and a measuring device for

Determining the radial extent of the tube and generating

corresponding first signals, wherein the device has a control unit which is connectable to the heating tube and the measuring device for determining the radial extent of the tube and processes the first signals and controls the heating tube for heating the tube accordingly. This device is operated with a closed tube, which with a

Atmospheric pressure is applied. Again, with the heating tube a rotationally symmetrical heating and a reproducible temperature profile can be provided. The overpressure ensures that the tube is in the

Forming section radially expanded until an equilibrium is established and the radial expansion is stopped. A big advantage of this device is that the Pipe does not have to be pressurized. A pressure source and a

Connection pieces are not required. For example, closed tubes with one, two or three bars of atmospheric pressure can be used, each leading to bubbles of well-defined dimensions without the need to adjust the pressure. The control unit interacts only with the measuring device for determining the radial extent of the tube and with the heating tube. Once the desired radial extent has been reached, the heating tube will be adjusted accordingly

switched off or shut down, with a certain inertia of the

Cooperation between the pipe and the heating pipe can be taken into account, so that switching off or shutting down is already something before

Achieving the desired radial extent can be completed. Due to the relatively simple structure sources of error are avoided This device is suitable for the production of mass products with the same dimensions, which nevertheless have a twist-free extension.

Preferably, the holding device has a first fixing section and a second fixing section, wherein the heating tube between the first and the second

Fixing section is arranged. In principle, it is possible to provide the holding device with only one fixing section, so that the tube only at one point during

Forming is held. In this case, it makes sense to arrange the pipe vertically during forming and to clamp it above the forming section, in order to keep bending during forming as low as possible on account of its own weight and the resulting bending moments. Still, that's a very accurate one

Process control is necessary in order not to heat the tube so far and thus soften that it bends or stretches during forming. In the

Using two fixing sections, between which the forming section is located, the tube can be clamped so that during forming virtually no forces and bending moments act in the forming section, so that very uniform and rotationally symmetrical bubbles arise.

Regardless of whether the tube is used with the two open ends or the tube which is exposed to an atmospheric pressure, it should again be pointed out that the tube is not rotated during forming must become. The tube must be clamped on both sides of the forming section and rotated there in known manufacturing processes. Even the smallest

Differences in the rotational speed lead to a twist when heating the tube. A transmission which almost completely synchronizes the rotational speeds at the two fixing sections is extremely expensive. Wear during operation could cancel the synchronization. These disadvantages are avoided according to the invention.

The device according to the invention is further developed in that between the gas source and the connector a valve for optional release or

Interrupting the gas flow is arranged in the pipe. The gas flow is used to set the pressure in the pipe. The valve makes it possible to increase the pressure when the tube has been heated for a certain time, whereby the formation of a twist can be further reduced. If a smaller or larger bubble is to be created, a lower pressure can be set in the tube, so that with the same

Device can be easily manufactured bubbles of different sizes, which increases the flexibility of the device according to the invention. In order to reduce the dead volume largely, while the valve is arranged as close as possible to the connector.

Preferably, the valve is designed as a multi-way valve, with which the tube can be optionally vented. In addition to the advantages already outlined for the valve, with the possibility of venting additionally influence on the

Production process of the bladder, whereby the manufacturing process can be performed faster and more reliable. In addition, it is advantageous if the multi-way valve is electrically switchable in order to be able to be integrated into a control or regulating circuit. With the closed tube is no

Pressure change possible, so that no valves are necessary in the apparatus for forming the closed tube.

In an advantageous embodiment, the heating tube is surrounded by an induction coil, wherein the heating tube consists of a material or comprises a material which can be heated with the induction coil. The use of an induction coil opens the possibility to bring the heating tube very precisely to the desired temperature, which is not possible, for example, with a gas burner. Consequently, the tube can be heated to a temperature which is optimal for forming the twist-free bubble. When using gas burners, the tube is heated more than necessary in many cases, which brings some adverse effects, especially when using borosilicate glasses. The excessive heating causes the evaporation of alkali borates, especially sodium borate, from the range which has been heated above the vaporization temperature of the alkali borates. On the one hand, the vaporized alkali borates diffuse into a somewhat cooler area in the near-surface region of the glass tube, which leads to an accumulation of alkali borates, which entails delamination processes and peel off small scale-like glass particles. On the other hand, the alkali borates deposit in significantly cooler areas on the surface and can mix with liquids that are passed through the glass tube, which can be very disadvantageous especially in analytical chemistry in detection tests. The usage of

Induction coils make it possible to heat the forming section only to the extent necessary for the forming. The evaporation of alkali borates is thus reduced to a harmless level. In addition, it comes to reinforced

Thermal stresses within the bladder, when the glass tube is heated very much, as is the case with the use of gas burners. The thermal stresses mean that cracks can occur during the separation of the semi-finished products, for example due to breaking or cracking, so that the individual components thus obtained are scrap. Furthermore, compared to induction coils, gas burners can be controlled significantly worse, which has the advantage that, with the use of induction coils, the process can be made slower and consequently more controlled, which leads to better results with respect to the geometries of the extension. Air currents do not interfere with inductive heating.

As an alternative to induction coils, it is possible to use resistance elements which also allow rotationally symmetrical heating and can be integrated into one

Integrate control loop, however, electrical wiring is necessary, the are exposed to high thermal loads and make replacement in case of malfunction or cleaning difficult.

The material used is preferably a nickel-based alloy. A nickel-base alloy has a low tendency to scale and a relatively good one

Dimensional stability at high temperature, so that the shape of the heating tube hardly changed during operation of the device. Any change in the shape of the heating tube also leads to uneven temperature distributions in the forming section, which in turn has a negative effect on the rotational symmetry of the bubble. Furthermore, it is preferred to keep the wall thickness of the heating tube and consequently the heat capacity as low as possible. This has the advantage that the temperature can be changed quickly and the manufacturing process can be made more accurate and faster. Furthermore, the heating tube should be well coupled to the high frequency field of the induction coil. An example of a preferred nickel-based alloy is 2.4952, which, in sum, best meets the stated requirements at the prevailing operating temperatures.

In a further preferred embodiment, the heating tube has an inner surface and one or two substantially perpendicular to the inner surface extending end faces, wherein the inner surface via a chamfer in the one end face or a first chamfer and a second chamfer in the two end faces passes. The design of the heating tube has a significant influence on the

Temperature distribution along the longitudinal axis of the tube when heated. Since glass is a poor conductor of heat, large temperature gradients arise between the heated and unheated portions of the pipe. The degree of heating is heavily dependent on the distance of the heating tube to the pipe. The chamfers ensure that the heating tube does not abruptly stop along the longitudinal axis of the tube, but that the distance to the tube gradually increases. Consequently, the

Temperature gradient between the heated and unheated portions of the tube less large, whereby the thermal stresses are less strong, which increases the stability of the tube, which, as already stated, positive on the

Separation process affects. In a further development, the device according to the invention has an insulation for thermal shielding of the device. The insulation stabilizes the thermal conditions within the Umformabschnitts and is able to vorzuhalten a temperature of up to 900 ° C in the forming section. As a result, the energy required to operate the device or to heat the heating tube and the tube is reduced, so that the device can be operated more cheaply. It is advantageous if the insulation between the induction coil and the heating tube is arranged, whereby in addition to the thermal and an electrical separation between the heating tube and insulation is effected. As a result, the reliability of the device is increased. The insulation is preferably made of a ceramic material, whereby the insulation also

Positioning purposes of the heating tube can be used. As will be explained later, it is important that the position of the heating tube does not change relative to the pipe in particular by the heating during the forming process, which is easy to achieve by a ceramic insulation. Furthermore, a ceramic insulation does not interfere with the interaction between the induction coil and the heating tube.

Furthermore, the device has a measuring device for determining the radial extent of the tube and for generating corresponding first signals. The forming process of the bladder can thus be tracked, so that it is possible to stop it precisely when the radial extent of the bladder has exceeded a certain level. Further, it is possible to change other essential parameters for the forming process as a function of the instantaneous radial extent of the bubble, for example the volume flow or the pressure of the gas flow into the tube or the temperature of the heating tube. The number of bubbles produced with the desired dimensions is increased so that the rejects are reduced.

Preferably, the measuring device is designed as an optical measuring device. Optical measuring devices have proven themselves in such applications and are inexpensive and easy to use. It can, for example, laser-based

Measuring devices are used, which provide the highest level of accuracy. It can be realized a kind of light barrier, which registers whether the radial extent of the bubble has reached or exceeded a certain level. In this case, the measuring device is preferably designed as a camera. The camera can be chosen so that a large working distance is possible at a low viewing angle. The lower the viewing angle, the lower the necessary depth of focus, so that less expensive cameras can be used. The cameras preferably have one

telecentric lens. The signals of the camera can be switched on

Image editing program evaluated and converted, for example, in diameter. Referring again to the applications of

Tubes of the invention in the laboratory and in particular in the analytical

Chemistry is the course of the inner diameter in the expansion of crucial importance, whereas with the camera, the outer diameter of the bubble is determinable. However, it has been found that the inner diameter and the

Outside diameter in a fixed function to each other, if one

reproducible and defined temperature profile in the forming section and

is adjusted in particular along the longitudinal axis of the tube. In this case, the outer diameter measured by the camera can be a simple one

mathematical correction can be converted into the inner diameter. In this context, it is important that the distance between the forming section and the camera during the forming process always remains the same, which can be achieved particularly well with the ceramic insulation.

It is advantageous if the measuring device comprises two cameras, which enclose an angle with respect to the tube. For each position of the camera results in a plane in which the radial extent can be measured most accurately. In this embodiment, the radial extent of the tube in the forming section can be measured in two planes, whereby in particular the rotational symmetry can be determined more accurately. It is advantageous if the angle which the cameras enclose with each other is approximately 90 °. In this area, the two planes have the greatest possible angular difference with respect to each other, so that the

Rotational symmetry can be determined as best as possible. Preferably, the device comprises a lighting unit for providing light for illuminating the pipe. In particular, when the measuring device is designed to determine the radial extent of the tube as a camera or as another optical measuring device, it is of particular importance that the tube is uniformly illuminated at least at the point at which its radial extent is to be determined without disturbing reflections. The lighting unit can be designed so that the lighting conditions are optimally adapted to the particular optical measuring device used in order to

to obtain consistently reproducible measurement results.

In a further embodiment, the device has a reflection region for the purposeful reflection of the light provided by the illumination unit within the device. As already stated above, the heating tube surrounds the tube in an annular manner. Consequently, it is not readily possible to illuminate the tube directly in the forming section, without causing reflections that emanate from the tube and can falsify the measurement results. By means of a

On the one hand, the reflection tube can illuminate the tube indirectly and yet sufficiently, without disturbing reflections, and on the other hand the illumination unit can be arranged flexibly spaced from the tube and from the heating tube, which simplifies the construction of the device.

In a particularly preferred embodiment, the device has a

Temperature measuring device for measuring the temperature of the heating tube or in the forming section of the tube or the closed tube and for generating corresponding second signals. For this purpose, known and suitable

Measuring sensors are arranged in the heating tube or in the forming section. Because there is up-to-date information regarding the temperature prevailing in the heating tube or in the forming section, the production process can be better controlled or regulated. The second signals are such that they can be read by a control unit. Since the temperature to which the tube or the closed is heated in the production process of the bubble, an important influence on the quality of the resulting bubble and its

Surface properties, it is particularly well possible in this embodiment, the bubbles with the desired quality and in particular with a high

To produce rotational symmetry and twist-free. It has been found that the temperature of the heating tube is better to measure than that of the pipe or the closed tube in the forming section, since in the latter case many disturbing influences can falsify the measurement results.

In this case, the temperature measuring device is preferably designed as a pyrometer.

A pyrometer allows the non-contact determination of the temperature in the pipe or the heating tube from a distance, so that no measuring sensors must be used, which are exposed to a strong thermal load. The same applies to other components that cause the measuring sensors, such as electrical cables, etc.

Furthermore, the temperature distribution in the forming section is not affected by the additional

Influenced components. It is particularly preferred, the pyrometer as

To design a quotient pyrometer, the influence of

Emissivity changes can be minimized.

Preferably, the fixing sections have grooves into which the pipe or the closed can be inserted and which are aligned along a longitudinal axis of the pipe. In this way, the fixing sections can be simple yet effective

be designed. The fact that the grooves are aligned along the longitudinal axis of the tube, the tube is in the fixed state virtually no stress on bending, which has a positive effect on the quality of the resulting bubble and its inner surface. In this case, the fixing each have a clamping unit, which act on the pipe so that the tube is fixable in the grooves. The clamping units can, for example, apply a force to the pipe, so that the pipe in the

Grooves is pressed and fixed due to the resulting friction between the grooves and the tube. The clamping units may, for example, be spring-loaded and therefore have a low overall height, so that they are suitable for the camera

limit the detectable area unnecessarily. Prism grooves are preferably used, which are to be understood as grooves with a V-shaped cross section. The opening angle is typically 90 °. The prism grooves have the advantage that they themselves center the object to be clamped, in this case the pipe. In a particularly preferred embodiment, the inventive

Device to a control unit, which is connectable to the multi-way valve, the heating tube, the temperature measuring device and the measuring device for determining the radial extent of the tube and the first signals and the second signals processed and the multi-way valve for introducing or interrupting the gas flow in the pipe or Vent and heat the heating tube to heat the glass tube. This embodiment relates to the apparatus for forming a tube with one or two open ends. In this embodiment, an automated control of the manufacturing process of the bubble can be realized. In this case, the outer diameter of the bubble can be detected almost continuously and the temporal change of the outer diameter compared with reference values. Depending on the result of the comparison, the temperature of the heating tube and / or the pressure in the tube can be changed by a corresponding control of the multiway valve. This control can produce a variety of bubbles of consistent quality with minimal waste. Furthermore, it allows the

Control to optimize the manufacturing process, for example by finding a specific temperature profile, which is passed through by the heating tube, so that the duration of the manufacturing process minimized and thus its effectiveness is increased. Also, the control unit can take into account the inertia of the manufacturing process and determine a "braking point." Even if at the same time the pressure in the pipe degraded and the heating tube is turned off, this does not mean that the bubble diameter can not increase To obtain a certain diameter, it is therefore necessary to stop the heating and reduce the pressure even if the desired diameter of the bubble is not reached, which is to be described by the term "braking point". The provision of such a control unit is only necessary for the pipe with the two open ends, since the pipe can be formed with the closed ends without control. In a further embodiment of the device, which relates to the forming of a closed tube, the control unit is connectable to the heating tube and the temperature measuring device, wherein the control unit processes the first signals and the second signals and the heating tube for heating the tube controls accordingly. The advantages that can be achieved in this embodiment correspond to those which have been discussed for the corresponding design of the device, which relates to the forming of a tube with one or two open ends.

The object is further achieved by a method for forming a tube, in particular a capillary tube, in a forming section, the tube having one or two open ends, comprising the following steps: holding and fixing the tube with a holding device,

Heating the tube with a heating tube which surrounds the tube in an annular manner,

Providing a gas flow by means of a gas source, and

Introducing the gas flow into the tube via at least one of the open ends with a fitting communicating with the gas source for adjusting the pressure in the tube, which is a radial extension of the tube in the

Forming section causes, wherein the tube is provided exclusively with the pressure provided by the gas source pressure in the forming section with a radial extension of the desired dimensions.

The advantages and technical effects which are achieved with the method according to the invention correspond to those which have been described for the device according to the invention. In particular, it is possible to rotationally symmetrically heat the tube without rotation about the longitudinal axis, whereby the tube can be provided with a bubble, which is largely free of twist or torsion and has a substantially flat inner surface.

The process according to the invention is developed with the following steps:

Determining the radial extent of the tube and generating

corresponding first signals by means of a suitably equipped measuring device, - Measuring the temperature of the heating tube or in the forming section of the tube and generating corresponding second signals by means of a

Temperature measuring device,

- Processing the first signals and the second signals by means of a

Control unit

- driving one between the gas source and the fitting

arranged multi-way valve with the control unit and optional release or interruption of the gas flow into the tube or optional venting of the tube by means of the multi-way valve, and

- Actuation of the heating tube with the control unit and optional heating of the tube with the heating tube.

In this embodiment, an automated control of the forming process of the tube can be realized. In this case, the outer diameter of the bubble detected almost continuously and the temporal change of the outer diameter with

Reference values are compared. Depending on the comparison result, the temperature of the heating tube and / or the pressure in the tube by a corresponding

Control of the multi-way valve to be changed. This control can produce a variety of bubbles of consistent quality with minimal waste. Furthermore, the method according to the invention makes it possible in this case

Embodiment, to optimize the manufacturing process, for example by finding a specific temperature profile, which is traversed by the heating tube, so that the duration of the forming process is minimized and thus its effectiveness is increased. The object is further provided by a method for forming a closed

Pipe, in particular a capillary tube, dissolved in a forming section, wherein the closed tube has a first and a second closed end and is acted upon by an atmospheric pressure, comprising the following steps:

Holding and fixing the closed tube with a holding device, and heating the closed tube with heating tube, which encloses the closed tube annular, Determining the radial extent of the closed tube and generating corresponding first signals by means of a suitably equipped measuring device,

Processing the first signals by means of a control unit, and

Actuation of the heating tube with the control unit and optional heating of the closed tube with the heating tube.

A significant advantage of this method is that the control is limited only to ensure when the desired radial extent of the tube is reached. Since the atmospheric pressure is already present in the closed tube, the closed tube only has to be heated with the defined, reproducible temperature profile and the heating must be stopped in good time so that bubbles of the same size are established.

Furthermore, the object is achieved by a computer program for operating a control unit with which a device for forming a tube, in particular a capillary tube, can be regulated in a forming section, the device comprising:

a holding device for holding and fixing the tube,

a heating tube, which encloses the tube in an annular manner and with which the tube can be heated,

a gas source for providing a gas flow, and

a connector communicating with the gas source for introducing the flow of gas into the tube via one of the open ends, whereby

Forming section by free forming a radial extension with the desired dimensions is malleable.

a multi-way valve for introducing or interrupting the gas flow into the pipe or for venting the pipe,

a temperature measuring unit for measuring the temperature of the heating tube or in the forming section of the tube and generating corresponding first signals, a measuring device for determining the radial extent of the tube and generating corresponding second signals,

wherein the computer program comprises program means for causing a computer to perform the following steps when the computer program is run on the computer:

Determining the radial extent of the tube and generating

corresponding first signals by means of the measuring device,

Measuring the temperature of the heating tube or in the forming section of the tube and generating corresponding second signals by means of

Temperature measuring device,

Processing of the first signals and the second signals by means of

Control unit

- Actuation of the multi-way valve with the control unit and optional

Releasing or interrupting the flow of gas into the pipe or selectively bleeding the pipe by means of the multi-way valve, and

Using the computer program according to the invention can be an automated

Control of the forming process of the bubble can be realized. It can the

Outside diameter of the bubble detected almost continuously and the temporal change of the outer diameter compared with reference values. Setpoints for the outer diameter can be entered via the computer. Depending on

Comparative result, the temperature of the heating tube changed and / or introduced the pressure in the tube, the mass flow of the gas stream changed or interrupted or the tube is changed by a corresponding control of the multi-way valve. This control can produce a variety of bubbles of consistent quality with minimal waste. Furthermore, the computer program according to the invention makes it possible to optimize the production process, for example by finding a specific temperature profile, which is passed through by the heating tube, so that the duration of the manufacturing process is minimized and thus its effectiveness is increased. A large amount of data can be collected and processed so that the manufacturing process goes through with a high degree of reproducibility can be. Furthermore, all of the processes that have been completed by the

Computer documented and evaluated. Such a computer program is not necessary for the closed pipe, but the computer program can be used analogously also for the closed pipe with the exception that no gas flow can be introduced into the closed pipe and the closed pipe can not be vented. Consequently, eliminates the control of the multi-way valve.

Furthermore, the invention relates to a tube and in particular a capillary tube having a longitudinal axis and an extension, wherein the extension in a selectable through the longitudinal axis extending first plane has an integer number of i> 1 upper radii and lower radii and for each number i the value

I, R,

Λ ',, + R .. calculated and the maximum value

A * _raax = MAx (AR _{i: rel} ) is searched, the value AR _{max being} 5% or less, more preferably 3% or less. The first plane is chosen arbitrarily and only has to fulfill the condition that it runs through the longitudinal axis or that the longitudinal axis runs in the first plane. The measurement is performed once for each tube, for example with the camera 56. If an extension meets this condition, it can be considered as

Essentially twisted or torsion-free. If the condition is not met, the pipe is sorted out and scrapped. A pipe with an ideal extension has a value of AR _max = 0%. Glass tubes and in particular capillary tubes with such an extension are particularly suitable for use in analytical chemistry, since they have a high degree of reliability and reliability due to their high precision with respect to the course and the surface properties of the extension

Support accuracy of evidence tests. In this case, the pipe according to the invention is preferably produced by one of the methods according to the invention, but this does not necessarily have to be the case. In addition, the value AR _i; In addition, it calculates in a second plane which is approximately perpendicular to the first plane and passes through the longitudinal axis and seeks the maximum value AR _max for the second plane, the value AR _{max being} 5% or less, in particular 3% or less. The corresponding measurements can be carried out with two cameras directed according to the tube. Using the device according to the invention and the method according to the invention, the radial extent forms very symmetrically and uniformly, so that it is sufficient to measure the radial extent only in one plane and to check whether the condition is fulfilled or not. Is it fulfilled, can with high

Probability to be assumed that it is fulfilled in every other level. However, non-uniformities could still occur, so that the condition is fulfilled in the first level, but not in the second level. In this embodiment, this case can be identified and the pipe in question can be sorted out, whereby in particular the reliability of the detection test, the

depends mainly on the precision of the radial expansion of the pipe, be further increased.

Preferably, the pipe or the closed pipe is along a

Separation level separated into two separate components. As a result, two components are produced, which have a funnel shape. In this embodiment, the tubes can be used for detection test. It is advisable that the plane is substantially perpendicular to the longitudinal axis and through the maximum inner diameter of the tube or the closed tube. There are two identical components created that can be used for example for the detection tests, so that the tube according to the invention can be used effectively.

It is preferred if the separated component has a length (X _T ) of 70 ± 35 mm, a maximum outer diameter of 1, 46 ± 0.73 mm and a minimum

Outer diameter of 1, 0 ± 0.5 mm, a maximum inner diameter (di, _ma x) of 1, 067 ± 0.5335 mm, minimum inner diameter (di, _min ) of 0.08 ± 0.04 mm and the forming section (66) has a length (X _F ) of 3.0 ± 1.5 mm. In this embodiment with these dimensions, the tube or the closed tube is particularly well suited for use in detection tests. Preferably, the tube or closed tube is borosilicate glass, with the forming section and unformed sections having substantially the same alkali borate concentration. In other words, the borosilicate glass tubes of the invention have no zones of depletion or accumulation of alkali borate. This is especially a consequence of

The forming process according to the invention, in which due to the use of the annular heating tube instead of gas burners, the tube is heated only to the extent necessary for the forming process. The necessary temperatures are approximately between 800 to 900 ° C, well below the

Evaporation temperature of the alkali borates, so it is not or none

substantial depletion or accumulation of alkali borates within the

Glass tube is coming. It forms no delamination zone or condensation zone, whereby a peeling of flaky glass particles or a

Migration of alkali borates in the guided in the pipe liquids is prevented. The invention will be explained below with reference to a preferred embodiment. Show it

1 shows a first embodiment of a device according to the invention for forming a tube based on a basic side view

2 shows a second embodiment of the device according to the invention for forming a closed tube, also with reference to a side view,

Figure 3 shows a comparison of a tube, which has an ideal course both with respect to the longitudinal axis and with respect to a plane passing through the maximum diameter plane, with a tube having a

Twist has FIG. 4 shows an isolated component, which is shown in FIG

5 shows the pipe according to the invention, shown along the separation plane E defined in FIGS. 3 and 4. FIG.

1 shows an embodiment of an inventive device 10i for forming a tube 1 1 is illustrated by a schematic diagram. The device 10i comprises an approximately U-shaped holding device 12 for holding and fixing the

Tube 1 1 with a first fixing portion 14 and a second fixing portion 16, each having a groove 18, in which the tube 1 1 can be introduced. The grooves 18 are aligned so that they are aligned as accurately as possible along a longitudinal axis L of the tube 1 1, so that the tube 1 1 can be fixed with the lowest possible bending load. The first fixing section 14 further comprises a first clamping unit 20 and the second fixing section 16 includes a second clamping unit 22 with which the tube 1 1 is pressed into the groove 18 and fixed without the tube 1 1 is damaged. The tube 1 1 has a first and a second open end 24, 26, wherein at the first open end 24, a connecting piece 28 is attached, which is connected via a channel 30 with a valve 32 and a gas source 34, so that gas from the gas source 34 can be introduced into the tube 1 1. As the gas, an inert gas or air may be used, and the gas should be dried to largely suppress condensation and reaction processes. The valve 32 is preferably designed as a multi-way valve 36, so that the pressure in the tube 1 1 can be changed quickly. The second open end 26 may be closed in a manner not shown, but this is not absolutely necessary.

In about the middle between the two fixing sections 14, 16, a heating tube 38 is arranged, which encloses the tube 1 1 annular. The heating tube 38 has an inner surface 40 facing the tube 1 1, and two end faces 42, which in the

Substantially perpendicular to the inner surface 40. The inner surface 40 merges via a respective chamfer 44 into the two end faces 42. In the example shown, the chamfer 44 has a chamfer angle of about 45 °. Alternatively, too a rounding be provided, with which the inner surface 40 in the

End faces 42 passes. The heating tube 38 comprises or consists of a material which can be heated by an induction coil 43 which radially surrounds the heating tube 38. Between the induction coil 43 and the heating tube 38, an insulation 46 is mounted, which surrounds the heating tube 38 fully and the heating tube 38 partially overlaps in the direction of the longitudinal axis L of the tube (see Figure 2).

Furthermore, the device 10T comprises a temperature measuring device 48 for measuring the temperature of the heating tube or the tube 11. In the example shown, the temperature measuring device 48 is designed as a pyrometer 50, so that the temperature of the heating tube or the tube 1 1 can be determined without contact and over a certain distance away. On the opposite side of the device 10i to the pyrometer 50 is a measuring device 52 for determining the radial

Extension of the tube 1 1 arranged, which is designed as an optical measuring device 54 and concretely as a camera 56. The camera 56 is arranged so that it encloses the smallest possible angle to the longitudinal axis L of the tube 1 1 in order to determine the outer diameter of the tube 1 1 as accurately as possible. For this purpose, the camera 56 has a telecentric lens. Further, the second one

Clamping unit 22, which is arranged on the same side of the device 10i as the camera 56, designed particularly flat, so as to obscure the tube 1 1 with respect to the camera 56 as little as possible.

In addition, the device 10-ι a lighting unit 58 for

Providing light for illuminating the tube 1 1, so that the camera 56 can detect the radial extent and in particular the diameter of the tube 1 well. Further, at the first fixing portion 14, which faces the camera 56, a reflection area 60 is attached, to which the lighting unit 58 is directed and which is provided with a light color. Thus, the tube 11 is illuminated indirectly, so that no disturbing reflections on the tube 1 arise. Furthermore, the light color increases the contrast, so that the camera 56 can detect the diameter of the tube 1 1 well. Furthermore, a control unit 62 is provided, which via electrical lines 64 to the camera 56, the induction coil 43, the pyrometer 50 and the

Multi-way valve 36 is connected and with which the forming process of the tube 1 1 can be controlled. If advantageous, a wireless connection between the camera 56, the induction coil 43, the pyrometer 50, the

Multi-way valve 36 and the control unit 62 are provided. Of the

Forming process is as follows:

The tube 1 1 is inserted into the grooves 18 and fixed with the clamping units 20, 22 in the two fixing sections 14, 16. Subsequently, the induction coil 43 is activated, so that the heating tube 38 and consequently also the tube 1 1 is heated. The multi-way valve 36 is brought into a position so that the gas flow from the gas source 34 is released into the tube 1 1 and the pressure in the tube 1 1 is changed. The temperatures of the heating tube 38 and / or the tube 11 are monitored with the pyrometer 50, wherein the pyrometer 50 generates first signals corresponding to the measured temperature. The radial extent and in particular the diameter of the tube 1 are determined with the camera 56, for which purpose the images recorded by the camera 56 are evaluated by image processing software and converted into second signals corresponding to the outer diameter of the tube 11

correspond.

As the heating increases, the tube 1 1 becomes softer and expands radially outward by the pressure, so that a bubble is created. The area which is expanded by the pressure and in which the inner diameter d 1 (see FIG. 4) of the tube 11 changes is to be defined as the forming section 66. The camera 56 is aligned to detect the maximum outer diameter of the bladder.

The outer diameter of the bubble corresponding to the first signals and the temperature of the heating tube or the tube 1 1 in the forming section 66th

corresponding second signals are transmitted to the control unit 62 and evaluated there. The heating tube 38 is activated by the induction coil 43 until a first temperature is reached. Then, the control unit 62 checks whether the bubble has reached a first maximum outer diameter. Is not that yet Case, the first temperature is maintained. If the first maximum diameter is reached, the induction coil 43 is switched off and the pressure in the tube 1 1 reduced by a corresponding control of the multi-way valve to ambient pressure. Due to the inertia of the system, the maximum diameter will continue to increase until after a certain waiting time a second maximum

Diameter is reached. Then the pressure is again increased and interrupted and the induction coil 43 is activated and turned off until the maximum outer diameter determined by the camera 56 deviates less than a predefinable amount from the desired maximum outer diameter. Then the

Transformation process completed and archived the data obtained.

FIG. 2 shows a second exemplary embodiment of the device 1 0 ₂ according to the invention, with which only closed tubes 67 with a first and a second closed end 68, 70 can be processed. The essential structure of the device 10 ₂ according to the second embodiment corresponds to the first embodiment 10i. But since the closed tubes 67 are already subjected to an atmospheric pressure and due to the closed ends 68, 70 by means of a gas flow no influence on the pressure in the closed tube 67 is and can be taken, no gas source 34 and consequently no

Connector 28 required. As already mentioned, a bubble with a certain radial extension automatically sets when a defined, reproducible temperature profile is provided by the heating tube 38. In this respect, it is also not necessary to provide a measuring device 52 for determining the radial extent of the closed tube 67. In the example shown, the

Device 10 ₂ , the temperature measuring device 48, which serves as a check, the target temperature with the actual temperature of the heating tube 38 using the

Control unit 62 to compare and intervene if necessary. As mentioned, the device 10i according to the first embodiment includes the same

Components such as the device according to the second embodiment 10 ₂ , but still has the additional components discussed above. In this respect, it is also possible, a closed pipe 67 with the device 10i after the first

Forming embodiment, for which the connector 28 is not connected to the closed pipe 67 and the control unit 62 either completely is switched off or adjusted so that it monitors only the temperature in the heating tube 38 and corrected if necessary.

FIG. 3 shows a comparison of a tube 1 1, which has an ideal course both with respect to the longitudinal axis L and with respect to a maximum diameter

Diameter extending singular plane E, with a pipe 1 1 _T , which has a twist. For reasons of illustration, the wall thickness of the tubes 1 1], 1 1 _{T is} not shown. The pipe 1 1, which has an ideal course, is shown by a solid line, while the pipe 1 1 _{T is provided} with twist with a dashed line. For clarification, a first upper radius R _{1> 0} relative to the singling plane E shown, a second upper radius R _2,0 , a first lower radius Ri _{, u} and a second lower radius R _{2, u} once for the pipe 1 1, with an ideal course and once drawn for the tube 1 1 _T with twist. For illustrative purposes, the respective radii for the tube with ideal course and with twist 1 1, and 1 1 _T are shown spaced from each other, but this does not change the following statement: It can be seen that regardless of the distance to the separation plane E, which by the maximum Diameter of the tube 1 1 j with ideal course of the first upper and the first lower radius R _{1 0} , Ri _{, u} and the second upper and the second lower radius R _2,0 , R2, _{u of} the tube 1 1, with ideal course respectively are the same, while the first upper and the first lower radius R _{1 i0} , Ri _{, u} and the second upper and the second lower radius R ₂ , ₀ , 2, u of the tube 1 _T with twist partially differ greatly from each other. In Figure 3, a isolated component is shown, which is obtained by separating the tube 1 1 in the plane E, which runs through the maximum diameter, is obtained. It can be seen that it is difficult for the pipe 1 _T with twist to decide where the pipe 1 1 is to be separated, since the separation plane E, which runs through the maximum diameter, in this case is not perpendicular to the longitudinal axis L.

The tube 1 1 according to the invention can be manufactured so precisely that it corresponds graphically to the tube 1 1, with an ideal course, so that in FIG. 3 there is no differentiation between the tube 1 1 according to the invention and the tube 1 with an ideal course. The tube according to the invention in this case has an extension, wherein the radii Ri _{, 0} and R _{ijLi satisfy the} following condition:

in which

ΔΛ _ηη = MAX {AR _rel )

and ARmax is 5% or less, especially 3% or less. The radii Ri, ₀ and Ri, _u and R _2,0 and R _{2, u} shown in FIG. 3 run in the same plane which runs through the longitudinal axis, but this does not necessarily have to be the case, but is advantageous for metrological reasons. The course shown in Figure 3 also applies to the closed pipe 67.

FIG. 4 illustrates a singulated component 72, as is predominantly used in practice, which has been obtained by separating the tube 1 1, 67 along the separation plane E shown in FIG. The tube 1 1, 67 and the separated component 72 has a radial extension 74, which by definition should be based on the inner diameter d, of the pipe 1 1, 67, it being assumed that the pipe 1 1, 67 before the Forming a constant inner diameter d. The radial extension 74 is intended to describe the region of the tube 1 1, 67 in which the inner diameter changes from dj _imin to d _iimax and back again to di, _mi n. The inner diameter di _{, min} corresponds to the inner diameter dj of the tube 1 1, 67 before forming. Since, as already explained, the singulated component 72 is separated along the separation plane E, where the inner diameter has its maximum value dj, _max , the radial extension 74 of the singulated component 72, consequently, describes the region in which the inner diameter changes from the value di, m _m to the value d _{,! max} . The course of the

Outside diameter d _a should be disregarded in the definition of the radial extension 74. The illustrated isolated component 72 has a length X _T of 70 ± 35 mm, a maximum outer diameter d _{a, max} of 1, 46 ± 0.73 mm and a minimum outer diameter di _{, min} of 1, 0 ± 0.5 mm. Furthermore, the singulated component 72 has a maximum inner diameter di, _max of 1, 067 ± 0.5335 mm, minimum inner diameter d _iimin of 0.08 ± 0.04 mm, wherein the forming section 66 has a length X _F of 3.0 ± 1, 5 mm. Thus, the ratios of d _max / di _imin vary approximately between 13.35 and 40 and of Xp dj max between 0.93 and 8.44.

In FIG. 5, the tube 1 1, 67 is defined along that in FIGS. 3 and 4

Singulation level E shown. The radii Ri _{, 0} and R _{1 iU} and R _2i0 and R _{2, u} shown in FIG. 3 are determined in a first plane i and in a second plane P ₂ , the planes Pi and P ₂ preferably being perpendicular to one another. This can be realized, for example, by two appropriately arranged cameras 56. Only if the above conditions are met in both planes Pi and P ₂ , the formed tube 1 1, 67 the required precision and can be released for the desired application. If the tube 1 1, 67 formed with the inventive device 0 and according to the inventive method, the radial extension 74 is very rotationally symmetrical that the desired precision is achieved in most cases, even if the above conditions only in a plane Pi or P _{2 are} met, so that one

Measurement in one of these levels or P _{2 is} sufficient. The measurement in the second plane P ₂ is used to increase the safety, so that pipes 1 1, 67, which differ due to a manufacturing error over a certain degree of rotational symmetry, not further used, but scrapped.

LIST OF REFERENCE NUMBERS

10, 1 OL 10 ₂ device

1 1 pipe

12 holding device

14 first fixing section

16 second fixing section

1 8 groove 20 first clamping unit

22 second clamping unit

24 first open end

26 second open end

28 connection piece

30 channel

32 valve

34 gas source

36 multiway valve

38 heating pipe

40 inner surface

42 face

44 chamfer

45 induction coil

46 insulation

48 temperature measuring device

50 pyrometers

52 measuring device

54 optical measuring device

56 camera 58 lighting unit

60 reflection unit

62 control unit

64 electrical line

66 forming section

67 closed pipe

68 first closed end 70 second closed end 72 isolated component

74 radial extension

E Singling level

L longitudinal axis

Pi first level

P ₂ second level

Ri, ₀ first upper radius

Ri _iU first lower radius

R ₂ , ₀ second upper radius

R ₂ , _u second lower radius

Claims

claims

Apparatus for forming a tube (1 1), in particular a glass tube and Kapiliarröhrchens, in a forming section (66), wherein the tube (1 1) has one or two open ends (24, 26) comprising

a holding device (12) for holding and fixing the tube (1 1), a heating tube (38) which surrounds the tube (1 1) annular and with which the tube (1) is heated when the tube () in the holding device (12) is introduced,

a gas source (34) for providing a pressure in the tube (11), and a fitting (28) communicating with the gas source (34) for introducing the gas flow into the tube (1) via one of the open ends (24, 26), whereby in the forming section (66) by free forming a radial extension (74) is formed with the desired dimensions.

Apparatus for forming a closed tube (67), in particular a glass tube and a Kapiliarröhrchens, in a forming section (66), wherein the closed tube (67) has a first and a second closed end (68, 70) and is acted upon by an atmospheric pressure , full

a holding device (12) for holding and fixing the closed tube (67) a heating tube (38), which encloses the closed tube (67) in an annular manner and with which the closed tube (67) can be heated when the tube (67) in the holding device (12) is introduced, whereby in

Forming section (66) by free forming a radial extension (74) is formed with the desired dimensions, and

a measuring device (52) for determining the radial extension of the

Pipe (1 1) and for generating corresponding first signals, characterized in that the device (10) comprises a control unit (62) connected to the heating tube (38) and the measuring device (52) for

Determining the radial extent of the tube (1) is connectable and processes the first signals and the heating tube (38) for heating the tube (1) controls accordingly.

3. Apparatus according to claim 1 or 2,

characterized in that the holding device (12) has a first

Fixing portion (14) and a second fixing portion (16), wherein the heating tube (38) between the first and the second fixing portion (14, 16) is arranged.

4. Apparatus according to claim 1,

characterized in that between the gas source (34) and the

Connecting piece (28) has a valve (32) for selectively releasing or

Interrupting the gas flow in the tube (1 1) is arranged.

5. Apparatus according to claim 4,

characterized in that the valve (32) is designed as a multi-way valve (36), with which the tube (1) can be optionally vented.

6. Device according to one of the preceding claims,

characterized in that the heating tube (38) by an induction coil (43) is surrounded and the heating tube (38) consists of a material or comprises a material which is heated with the induction coil (43).

7. Apparatus according to claim 6,

characterized in that the material is a nickel-based alloy.

8. Device according to one of the preceding claims,

characterized in that the heating tube (38) has an inner surface (40) and one or two end faces (42) substantially perpendicular to the inner surface (40), the inner surface (40) being chamfered (44) in the one end face (42) or via a first chamfer (44-i) and a second chamfer (44 ₂ ) merges into the two end faces (42).

9. Device according to one of the preceding claims,

characterized in that the device comprises insulation (46) for thermal shielding of the device (10).

10. Apparatus according to claim 7,

characterized in that the insulation (46) between the induction coil (43) and the heating tube (38) is arranged.

1 1. Apparatus according to claim 1 or any one of claims 4 to 10,

characterized in that the device comprises measuring means (52) for determining the radial extent of the tube (12) and generating corresponding first signals.

12. Device according to claim 1 1,

characterized in that the measuring device (52) as an optical

Measuring device (54) is formed.

13. Device according to claim 12,

characterized in that the measuring device (52) is designed as a camera (56).

14. Device according to claim 13,

characterized in that the measuring device (52) comprises two cameras (56) which enclose an angle relative to the tube (11).

15. Device according to one of claims 12 to 14,

characterized in that the device (10) comprises a lighting unit (58) for providing light for illuminating the pipe (11).

16. The device according to claim 15,

characterized in that the device (10) has a reflection region (60) for targeted reflection of the light provided by the illumination unit (58) within the device (10).

17. Device according to one of the preceding claims, characterized in that the device comprises a temperature measuring device (48) for measuring the temperature of the heating tube (38) or in the forming section

(66) of the tube (1 1) or the closed tube (67) and for generating corresponding second signals.

18. Device according to claim 17,

characterized in that the temperature measuring device (48) is designed as a pyrometer (50).

19. Device according to one of the preceding claims,

characterized in that the fixing portions (14, 16) have grooves (18) into which the tube (1 1) or the closed tube (67) can be introduced and along a longitudinal axis (L) of the tube (1 1) or the closed pipe (67) are aligned.

20. Device according to claim 19,

characterized in that the fixing sections (14, 16) each have a clamping unit (20, 22), which on the pipe (1 1) or on the closed tube

(67) act, that the tube (1 1) or the closed tube (67) is fixable in the grooves.

21. Device according to claim 5 and one of claims 1 1 to 15 and one of claims 17 to 20,

characterized in that the device (10) comprises a control unit (62) connected to the multiway valve (36), the heating tube (38), the

Temperature measuring device (48) and the measuring device (52) for determining the radial extent of the tube (1 1) is connectable and the first signals and the second signals processed and the multi-way valve (36) for introducing or interrupting the gas flow into the tube (1 1 ) or for venting and the heating tube (38) for heating the tube (1 1) controls accordingly.

22. Device according to claim 2 and 17 or 18 and one of claims 19 or 20, characterized in that the control unit (62) with the heating tube (38) and the temperature measuring device (48) is connectable and processes the first signals and the second signals and the heating tube (38) for heating the tube (1 1) controls accordingly.

Method for forming a glass tube (1 1), in particular a

Capillary tube, in a forming section (66), wherein the tube (11) has one or two open ends, comprising the following steps:

Holding and fixing the glass tube (1 1) with a holding device (12),,

Heating the glass tube (1 1) with a heating tube (38), which surrounds the tube (1 1) annularly,

- Providing a gas stream by means of a gas source (34), and introducing the gas flow into the tube (1 1) over at least one of the open ends with a gas source (34) communicating fitting (28) for adjusting the pressure in the tube (1 1 ), which causes a radial expansion of the tube (1 1) in the forming section (66), wherein the tube (1 1) exclusively with the gas source (34) provided pressure in the forming section (66) with a radial extension (74) the desired dimensions is provided.

The method of claim 23, further comprising the steps of:

Determining the radial extent of the tube (11) and generating corresponding first signals by means of a correspondingly established measuring device (52),

- Measuring the temperature of the heating tube (38) or in the forming section (66) of the glass tube (1 1) and generating corresponding second signals by means of a temperature measuring device (48),

- Processing the first signals and the second signals by means of a

Control unit (62),

- Controlling a between the gas source (34) and the connecting piece (28) arranged multi-way valve with the control unit (62) and optional release or interruption of the gas flow into the tube (1) or

optional venting of the glass tube (1 1) by means of the multi-way valve, and - Driving the heating tube (38) with the control unit (62) and optional heating of the glass tube (1 1) with the heating tube (38).

A method of forming a closed tube (67), particularly a capillary tube, in a forming section (66), said closed tube (67) having first and second closed ends (68, 70) and being exposed to an atmosphere overpressure comprising Steps:

- Holding and fixing the closed tube (67) with a holding device (12),, and

Heating the closed tube (67) with a heating tube (38) which encloses the closed tube (67) in an annular manner,

Determining the radial extent of the closed tube (67) and generating corresponding first signals by means of a suitably equipped measuring device (52),

- Processing the first signals by means of a control unit (62), and

- Driving the heating tube (38) with the control unit (62) and optional heating of the closed tube (67) with the heating tube (38).

Computer program for operating a control unit (62), with which a device (10) for forming a tube (1 1), in particular a

Glass tube and a capillary tube, is adjustable in a forming section (66), the device comprising:

- A holding device (12) for holding and fixing the tube (1 1)

- A heating tube (38) which surrounds the tube (1 1) annular and with which the tube () is heated,

a gas source (34) for providing a gas flow, and

a connection piece (28) communicating with the gas source (34) for

Introducing the gas stream into the tube (11) via one of the open ends, whereby in the forming section (66) by free forming a radial

Extension (74) with the desired dimensions,

- A multi-way valve (36) for introducing or interrupting the gas flow into the tube (1 1) or for venting the tube (1 1), - Measuring means (52) for determining the radial extent of the tube (1 1) and generating corresponding first signals,

- A temperature measuring unit for measuring the temperature of the heating tube (38) or in the forming section (66) of the tube (1 1) and generating

corresponding second signals,

wherein the computer program means for initiating a program

Computer includes the following steps if the

Computer program running on the computer:

- Determining the radial extent of the tube (1 1) and generating

corresponding first signals by means of the measuring device (52),

- Measuring the temperature of the heating tube (38) or in the forming section (66) of the tube (1 1) and generating corresponding second signals by means of the temperature measuring device (48),

Processing of the first signals and the second signals by means of

Control unit (62),

- Controlling the multi-way valve with the control unit (62) and optional release or interruption of the gas flow into the tube (1 1) or optional venting of the glass tube (1 1) by means of the multi-way valve, and

- Driving the heating tube (38) with the control unit (62) and optional heating of the tube (1 1) with the heating tube (38).

Pipe (1 1) or closed tube (67), in particular glass tube and

A capillary tube having a longitudinal axis (L) and a radial extension (74), wherein the radial extension (74) in a select through the longitudinal axis (L) extending first plane (Ρτ) an integer number of i> 1 upper radii and lower radii and li is the value

calculated and the maximum value

A _max = MAX (AR ,,. J

is sought, wherein the value AR _max 5% or less, in particular 3% or less.

28. tube (1 1) or closed tube (67) according to claim 27,

characterized in that the value AR _{i; re} i is additionally calculated in a second plane (P ₂ ) which is approximately perpendicular to the first plane (Pi) and passes through the longitudinal axis (L) and the maximum value ARm _ax for the second level (P ₂ ) is sought, wherein the value AR _max 5% or less, in particular 3% or less.

29. tube (1 1) or closed tube (67) according to any one of claims 27 or 28, characterized in that the tube (1) or the closed tube (67) along a separation plane (E) is separated into two separated components.

30. tube (11) or closed tube (67) according to claim 29,

characterized in that the plane (E) is substantially perpendicular to the longitudinal axis (L) and by the maximum inner diameter (di, max) of the tube (1 1) or the closed tube (67).

31. Pipe (1 1) or closed pipe (67) according to claim 29 or 30,

characterized in that the singulated component has a length (Χτ) of 70 ± 35 mm, a maximum outer diameter (dj _, ma _X ) of 1, 46 ± 0.73 mm and a minimum outer diameter (d _a , _m in) of 1, 0 ± 0.5 mm.

32. Pipe (1 1) or closed pipe (67) according to one of claims 29 to 31, characterized in that the separated component has a maximum

Internal diameter (di _{, max} ) of, 067 ± 0.5335 mm, minimum inner diameter (di.min) of 0.08 ± 0.04 mm.

33. Tube according to one of claims 29 to 32,

characterized in that the forming section (66) has a length (X _F ) of 3.0 ± 5 mm. Tube (11) or closed tube (67) according to one of claims 27 to 33, characterized in that the tube (1 1) or the closed tube (67) consists of borosilicate glass and the forming section (66) and the non-deformed sections in Have substantially the same alkali borate concentration.