DE102011001329B3 - Controlling peripheral speed of transport rollers of glass tube manufacturing plant, comprises providing transport rollers for removing hot glass tube strand, and assigning transport roller of contactless measuring speed sensor - Google Patents

Abstract

The method comprises: providing the transport rollers for removing hot glass tube strand (2), which is associated with drive units for driving the respective associated transport roller or the transport roller and has a deduction device downstream present in deduction direction of the glass tube strand for removing the glass tube strand with a predetermined speed; and assigning the transport roller of a contactless measuring speed sensor that measures an actual deduction speed of the glass tube strand in an area of the respective associated transport roller. The method comprises: providing the transport rollers for removing hot glass tube strand (2), which is associated with drive units for driving the respective associated transport roller or the transport roller and has a deduction device downstream present in deduction direction of the glass tube strand for removing the glass tube strand with a predetermined speed; assigning the transport roller of a contactless measuring speed sensor that measures an actual deduction speed of the glass tube strand in an area of the respective associated transport roller; and introducing a control- or regulating device of the measured actual deduction speed of the glass tube strand. The control- or regulating-device regulates/controls the peripheral speed of the transport roller to minimize or to control a difference between the actual deduction speed in the area of the respective associated transport roller and the peripheral speed of the transport rollers, which have wedge-shaped support surfaces. The peripheral speed of the transport roller is measured: in the area of a support point of the glass tube strand on the wedge-shaped support surface or at a plant- or measuring-point corresponding to the respective support point with the same peripheral speed; and without contact by a laser-Doppler-measuring method or touching by a speed-measuring roller contacting the respective transport roller. The support point of the glass tube strand is optically detected on the support surface. A position of a measuring range is varied on the support surface. The control- or regulating-device is a function of the measured peripheral speed of a controlled variable to the drive unit so that the difference between the actual measured peripheral speed in the range of the transport roller and the peripheral speed of the transport roller is controlled to a zero value. The control- or regulating-device of the control variable or a correction value for the control variable in dependence of sizes is calculated as the measured actual deduction speed of the glass tube strand, temperature in the range of the transport roller, outer radius of the transport roller, position of the support point on a support surface of the transport roller, linear expansion coefficient of a glass material of the glass tube strand, position of the transport roller along a drawing path for removing the glass tube strand. The calculated control variable is displayed to the drive unit to control the peripheral speed of the respective associated transport roller or the transport rollers, which are: divided by a coupling device in a row of groups of the transport rollers whose peripheral speed is regulated or controlled in groups corresponding to a standard- or control-variable; and arranged in a region in which the temperature of the glass tube strand above a solidification temperature of the glass material of the glass tube is 350[deg] C. The temperature of the glass tube strand is measured at a first transport roller of the transport rollers with which the temperature of the glass tube strand is cooled to the solidification temperature of the glass material of the glass tube strand. The peripheral speed of the transport rollers is controlled or regulated corresponding to a thermal linear contraction of the glass tube strand and the respective position of each transport rollers with which the temperature of the glass tube strand is measured. Independent claims are included for: (1) a computer program product; and (2) an apparatus for controlling the peripheral speeds of transport rollers of a glass tube manufacturing plant.

Description

Field of the invention

The present invention relates to a method and a device for controlling the peripheral speeds of transport rollers for a glass tube manufacturing plant, in particular also in the form of a software or a computer program product for implementing a corresponding control or regulation method.

Background of the invention

In a glass tube manufacturing plant, such as this example in the DE 1 074 225 A is disclosed, depending on the manufacturing method (Vello method or Danner method, down-draw method), a hot glass tubing is withdrawn from a die or a Danner whistle of the glass tube manufacturing plant and then the still in a deformable state located hot glass tubing deflected horizontally, to then be transported along a pull path to downstream processing stations on. For this purpose, the still hot glass tubing string rests on a plurality of V-shaped transport rollers, which are usually made of graphite, in order to be able to adequately withstand the high temperatures prevailing along the draw path. The glass tubing is withdrawn along this draw line by means of a take-off device located at a location remote from the fused glass stock. To avoid non-circular workpieces and to produce glass tubes with uniform wall thickness, it is also common to twist the glass tubing in the still plastic state about its longitudinal axis, which can be achieved by suitable rotation of the workpiece.

In such a glass tube manufacturing plant, a device for controlling the peripheral speeds of the transport rollers is provided. Usually, the peripheral speed of the transport rollers is set to the withdrawal speed predetermined by the withdrawal device. However, the transport rollers immediately after removal from the melt stock, ie at the beginning of the draw, with respect to the transport direction of a higher temperature exposed than the further downstream transport rollers, so that in the upstream transport rollers a greater thermal expansion and thus a larger roller radius results. Because the drive means associated with the transport rollers each specify a rotational frequency, as a result, the peripheral speeds of the transport rollers vary along the drawing path, in accordance with the respective prevailing temperature profile.

This can lead to a slippage of the glass tube strand on the respective transport rollers and thus to a detachment of small particles of coal from the surface of the transport rollers, which leads to disturbing small black dots on the glass tube surface and can interfere with subsequent processes. However, the different actual peripheral speeds also result in local stresses and local deformations, such as bumps or areas of different wall thickness, thus affecting the quality of the glass tubes. The aforementioned problems become more serious the thinner the wall thickness and the smaller the diameter of the glass tube strand to be transported.

To reduce the abrasion in such transport systems, according to a first approach, such as in US 5,688,300 A or US 5,766,298 A discloses the configuration of the transport rollers are designed appropriately.

According to another approach, such as in US 4,312,659 A . US 3,278,286 A or DE 101 13 344 A1 discloses an attempt is made to support the still hot glass tubing strand on an air cushion substantially non-contact and to allow to slide substantially contactless. However, this approach is relatively expensive and is therefore used restrained in practice.

In another context, namely in the context of the production and the removal of flat glass or strip glass, is in the DE 37 22 268 A1 , according to the GB 2 194 209 A , a method for controlling the peripheral speeds of a plurality of transport rollers of a flat glass manufacturing plant proposed having a plurality of transport rollers, which are arranged side by side in a Flachglasvergütungskühlkanal and which are associated with drive means for the drive. In this case, a control device for controlling the peripheral speeds of the transport rollers is provided, which touch a portion of the flat glass at locations which are downstream with respect to the transport direction with respect to a substantially central position, so that it is higher than a feed rate of the flat glass. The peripheral speeds of the transport rollers can be controlled so that there is a sufficiently small difference between the actual feed rate of the flat glass and the peripheral speed of the respective transport rollers, so that the flat glass surface is not removed or mechanically damaged. The transport rollers may also be divided into a number of groups, each driven at different peripheral speeds, to one thermally induced length contraction of the flat glass during cooling along the draw sheet account.

Summary of the invention

The object of the present invention is to provide a method and an apparatus for controlling the peripheral speeds of transport rollers of a glass tube manufacturing plant, whereby the conditions during transport of a still hot glass tubing along a drawing path of a glass tube manufacturing plant can be further improved. A further aspect of the present invention relates to the use of such a method or apparatus in the manufacture of glass tubes and a corresponding computer program product (software) to be able to control or control the peripheral speeds of transport rollers along a drawing path of a glass tube manufacturing plant.

These objects are achieved by a method according to claim 1, an apparatus according to claim 14, uses according to claim 12 or 25 and by a computer program product according to claim 13. Further advantageous embodiments are the subject of the dependent claims.

In a method in accordance with the present invention, a still hot glass tubing string is withdrawn along a draw path comprising a plurality of transport rollers at a predetermined speed. Along the drawing path, a non-contact measuring speed sensor is assigned to at least one transport roller, which measures at a defined position an actual local take-off speed of the glass tube strand in the region or in the respectively assigned transport roller. Preferably, such a speed measurement is carried out distributed not only at one position but at a plurality of positions in the withdrawal direction along the draw path. The measured actual take-off speed of the glass tubing is entered as the actual speed of a controller which controls the peripheral speed of the at least one transport roller, more preferably of all or all of the transport rollers along the draw path, by a difference between the actual take-off speed in the range or to minimize or control the respectively associated transport roller and the actual peripheral speed of the respectively assigned transport roller or transport rollers. The minimization or control of the peripheral speeds is carried out so that an abrasion or other disturbing effects, such as denting, local mechanical deformation or varying wall thickness or diameter of the glass tube, to a sufficient extent, as dictated by the respective specifications of the glass tube, are minimized. For this purpose, it may in principle be sufficient if the respective slip of the glass tube strand on the transport rollers is sufficiently low, so that not necessarily the peripheral speeds of all transport rollers controlled, in particular must be controlled. This depends on the specific specifications of the glass tube and the characteristics and process parameters of the glass tube manufacturing plant.

More preferably, however, several or all of the transport rollers are sufficiently controlled or regulated with respect to their respective peripheral speeds, as set forth below. Thus, the quality of the glass tubes according to the invention can be further improved in a simple manner.

According to another aspect of the present invention, the peripheral speed of the respective associated transport roller is measured by contact or non-contact measurement and input to the control device as a parameter for controlling the respective peripheral speed.

According to another aspect, the transport rollers may each have wedge-shaped contact surfaces, so that the actual local peripheral speed varies at a given speed of the respective transport roller depending on the local radius at the two support points of the glass tubing on the wedge-shaped support surface. According to a preferred further aspect of the present invention, the peripheral speed of the respective transport roller at the respective contact point of the glass tube strand on the wedge-shaped bearing surface or at a corresponding investment or measuring point, which has the same peripheral speed as the respective support point, measured. In other words, the local peripheral speed of the respective associated transport roller is either measured directly at the respective support point of the glass tube strand on the wedge-shaped bearing surface or precautions are taken that the local peripheral speed at another circumferential position of the respective transport roller with the same effective radius and thus the same Peripheral velocity is measured. For this purpose, for example, the respective support points of the glass tube strand on the wedge-shaped bearing surface can be optically determined contact or identified and based on these support points at another measuring point with the same peripheral speed, d. H. the same effective radius, the actual peripheral speed are measured touching or non-contact.

For optical detection of the respective support points of the glass tube strand on the wedge-shaped bearing surface thereby optical signals, such as a laser or an LED, or by means of a camera optically captured images can be suitably evaluated. For non-contact measurement of the actual circumferential speed, laser Doppler measuring methods are particularly suitable, as are known in principle from the prior art, since they can be executed without contact with high spatial resolution. For touching measurement of the respective local peripheral speed, a speed measuring roller can rest against the wedge-shaped bearing surface of the respective transport roller at a suitable contact or measuring point, ie at a position at the same peripheral speed as the corresponding contact point of the glass tube strand on the wedge-shaped bearing surface. Of course, the actual local peripheral speed of the transport roller can be measured spatially resolved with any other touching or non-contact measuring methods.

According to a preferred aspect of the present invention, the control or regulating device is designed as a control device, depending on the respective measured peripheral speed and the actual withdrawal speed of the glass tubing a suitable control variable to the respective transport roller associated drive means output so that the difference between the actual measured departure speed in the area or at the respective associated transport roller and the peripheral speed of the respective associated transport roller is controlled to a zero value or so that this difference is in any case smaller than a predetermined threshold.

Depending on the specifications of the glass tube to be complied with, however, it may be sufficient according to the invention if the control or regulating device actually acts as a control device which, depending on various process parameters, as explained below, a control variable or a correction value for such a control variable for one of the respective transport role assigned drive means calculated and outputs to the respective drive means, so that the peripheral speed of the respective associated transport roller or transport rollers is suitably controlled to meet the respective specifications of the glass tube can (for example, abrasion, local deformation, fluctuation of wall thickness or glass tube diameter).

The plurality of transport rollers along the drawing path can be subdivided by means of at least one coupling device into a series of groups of transport rollers whose respective peripheral speed is controlled or controlled in groups according to the respective control or control variable. According to the invention, the peripheral speeds of all transport rollers of the draw web are very preferably controlled or regulated in a region in which the glass tube strand is still comparatively hot, whose temperature is still above a solidification temperature of the glass material or a predetermined temperature, for example 350 ° C. or 400 ° C. , lies. However, depending on the specifications of the glass tube to be complied with, according to the invention it may be perfectly sufficient if the peripheral speeds of all the transport rollers of a respective subgroup of transport rollers are suitably controlled, but the peripheral speeds vary depending on the subgroups.

The actual peripheral speeds of the transport rollers can take into account further aspects of the production process, in particular a thermal length contraction along the drawing path caused by the cooling of the glass tube strand during the withdrawal along the drawing path. While these conditions are automatically taken into account in a regulation of the respective peripheral speeds, in a control according to the present invention, this length contraction can be calculated in advance or online according to the prevailing temperature profile and then based on this temperature profile and the resulting length contraction then a suitable Control quantity or a suitable correction variable for such a control variable.

In order to detect the prevailing temperature profile, a plurality of temperature sensors can thereby be distributed along the pull path, which preferably each measure the temperature directly in the case of an associated feed roller. In principle, it may be sufficient to measure the temperatures at the beginning and at the end of the drawing web, wherein the last measuring point should be in a place where the temperature of the glass tube strand has already cooled below the solidification temperature of the glass material or below a predetermined temperature value, or 350 ° C or 400 ° C. Of course, the local temperature for detecting a more accurate temperature profile can also be measured at several positions. Of course, the temperature profile can also be fixed, for example due to a one-time measurement for corresponding process parameters of the glass tube manufacturing plant.

Further aspects of the present invention relate to one for carrying out the method described above designed device for controlling the peripheral speeds of a plurality of transport rollers of a glass tube manufacturing plant. This device can be delivered as an independent control or regulation unit, also for retrofitting existing production facilities. Of course, a computer program product, in particular in the form of suitable software, for the implementation of the above-described control or regulation method can also be delivered separately.

LIST OF FIGURES

The invention will now be described by way of example and with reference to the accompanying drawings, from which further features, advantages and objects to be achieved will result. Show it:

1 a schematic representation of a control device for a glass tube manufacturing plant according to the present invention;

2a in a plan view of a transport role of the control device according to the 1 with a portion of a glass tubing conveyed from this roll;

2 B in a sectional view of the transport roller according to the 2a associated with measuring means for measuring the peripheral speed according to a first embodiment of the present invention;

2c in a sectional view of the transport roller according to 2a a measuring device for measuring peripheral speed according to another embodiment of the present invention; and

3 in a schematic representation of a section of a control device according to another embodiment of the present invention.

In the figures, identical reference numerals designate identical or essentially identically acting elements or groups of elements.

Detailed description of preferred embodiments

The 1 shows a partial section of a glass tube manufacturing plant with a control device according to a first embodiment of the present invention. According to the 1 becomes a still plastically deformable glass tube 3 from a drawing nozzle 4 in the manufacture of a glass tubing string 2 deducted by the known Vello method. For this purpose, a central extraction device 5 arranged in a region in which the glass tube strand has already cooled sufficiently. When pulling off the drawing nozzle 4 is the still plastically deformable glass tube 3 horizontally deflected and the glass tubing 2 by means of a plurality of transport rollers R1-R8 to the extraction device 5 deducted. The from the drive motor 6 driven extraction device 5 indicates the take-off speed with which the glass tube strand 2 is pulled off over the drawing web formed by the transport rollers R1-R8.

According to the 1 Each of the transport rollers R is a motor M assigned to drive the respective associated transport roller R. While the glass tubing 2 is substantially still plastically deformable in the region of the first transport roller R1, is the glass tube strand 2 in the area of the extraction device 5 already cooled to a temperature below the solidification temperature of the glass material. The glass tubing 2 thus undergoes a temperature profile in the drawing direction, which essentially by the process parameters of the system 1 is predetermined. This leads to a certain thermal length contraction and also decrease in the dimensions (outer diameter and inner diameter) of the glass tube strand 2 ,

Like in the 2a shown points each of the transport rollers 10 , which are preferably formed of graphite or along the circumference have a circumferential surface of graphite, a wedge-shaped bearing surface 11 on, preferably with flat side legs, as in the 2a shown. The temperature of the glass rolls 10 is essentially due to the temperature of the glass tubing conveyed by it 2 specified. Thus, the actual radius of the respective transport rollers R (see FIG. 1 ) due to the thermal expansion corresponding to the respective position along the drawing path. Since with the drive motors M only the speed of the respective transport rollers R can be specified, the actual peripheral speed of the respective varies accordingly. Transport rollers according to the prevailing Tempertaturbedingungen. This leads without a corresponding compensation to a certain slip and affect the quality of the glass tube.

To avoid these effects, according to the invention is a central control or regulating device 8th which outputs control variables C1-C8 for the respective drive motors M1-M8 (or outputs correction values for such control variables according to an alternative embodiment (cf. 3 )), so that the respective peripheral speeds of the transport rollers R1-R8 can be appropriately controlled or regulated. In principle, all transport rollers R1 can be individually controlled or regulated, for which purpose all transport rollers R1-R8 must be decoupled from each other. Like in the 1 illustrated, however, at least one coupling device 7 to divide the plurality of transport rollers R1-R8 into a series of groups of transport rollers (for example, first group: R1-R3, second group: R4-R6, third group: R7-R8), the respective peripheral speeds of all the transport rollers a suitable group can be controlled or controlled as described in more detail below.

To record the actual take-off speed of the glass tubing 2 In a control device according to the invention, at least one speed sensor VS is provided, which measures the actual speed without contact. For this purpose, suitable non-contact measuring methods are known from the prior art. According to a preferred embodiment, use is made of a laser Doppler measuring method. Suitable laser Doppler velocimeters are known in the art. These can measure the Doppler frequency shift, for example, interferometrically. The underlying measuring principle is based on the electronic evaluation of the Doppler frequency shift of scattered light from moving objects (here glass tube strand 2 ). In this case, a laser beam is split with the aid of a beam splitter into two beams and merged again in the measuring volume. Alternatively, one can also obtain an image of the velocity distribution by arranging two laser Doppler line sensors with which not only the velocity but also the position of a scattering object (here glass tube strand 2 ) can be detected accurately. In this case, the laser light is scattered on the surface of the measurement object, wherein characteristic scattered light patterns are formed by spatially different reflection coefficients and in particular the speckle effect. In the scattering of coherent light on a surface whose roughness is greater than approximately one quarter of the wavelength of light, this results in stochastic amplitude fluctuations and phase jumps, which distort the signal spectrum to be evaluated. With the help of specially adapted signal evaluation methods, a low measurement uncertainty for the Doppler signal frequency can be achieved even on rough solid surfaces. At the same time a high spatial resolution can be realized. Such laser Doppler measuring methods are outstandingly suitable for online process monitoring in the production of glass tubes.

As indicated by the dots between the speed sensors VS in the 1 indicated, the actual withdrawal speed of the glass tubing string 2 also be measured and evaluated at several positions. The respective measurement expediently takes place in the region or near a respective assigned transport roller R1-R8. Since, however, knowing the actually prevailing temperature profile and the coefficient of thermal expansion of the glass material, the actual take-off speeds can also be calculated, the prevailing withdrawal speed, for example, in the region of the first transport roller R1 by means of the associated speed sensor VS1 and in the region of the last transport roller R8 of the Draw train by means of the associated speed sensor VS8 to measure. The measured values become the control or regulating device 8th entered.

In addition, the control or regulating device 8th according to a first embodiment, the actual peripheral speeds of the transport rollers input, the measurement of which is based on the 2a to 2c should be described by way of example. According to the 2 B sofft the actual peripheral speed of the transport roller 10 touching with the aid of a measuring roller resting against it 16 . 17 be measured. In principle, it may be sufficient, the peripheral speed of the transport roller 10 in the middle of the transport roller 10 , ie in the expected contact area, to measure. According to a more refined embodiment, which is disclosed in US 2 B is represented by means of an imaging optics 20 and a camera 21 or a comparable image capture device the actual support point 12 . 13 of the glass tube 2 on the wedge-shaped bearing surface 11 determines, in particular the respective position in the axial direction. As indicated by the dashed lines, correspond to these two investment points 12 . 13 measuring points 14 . 15 with the same peripheral speed (the same effective radius RR) at which the respective measuring rollers 16 . 17 abutment to measure the respective peripheral speed touching at this axial position. Around these measuring rollers 16 . 17 To lead to the respective axial position, an associated adjusting device (not shown) may be provided, as in the 1 indicated by the double arrow. In addition, the position of the investment points 14 . 15 the measuring rollers 16 . 17 on the wedge-shaped bearing surface 11 also by means of another imaging optics 20 and image capture device 22 Be recorded online. In this way, two actual peripheral speeds of the transport roller 10 measured. In this case, the arithmetic mean value of these two measured quantities can be used as input variable for the control or regulating device.

In the embodiment according to the 2c becomes the peripheral speed of the transport roller 10 measured without contact. This is a used optical measuring method in which by means of an imaging optics 20 and an image capture device 23 together with assigned evaluation unit (not shown) the position of the support points 12 . 13 of the glass tube 2 on the wedge-shaped bearing surface 11 is determined. As indicated by the dashed lines, the peripheral speed by means of the further imaging optics 20 and image capture device 24 together with assigned evaluation unit (not shown) at measuring points 18 . 19 that these support points 12 . 13 correspond, ie have the same peripheral speed (effective radius RR), measured without contact. For this purpose, a laser Doppler measurement method can be used. The speed measurement is carried out spatially resolved, according to the axial positions of the support points 12 . 13 , As an input variable for the control or regulating device, an arithmetic mean of the two measured values can be used, for example. In principle, however, it may be sufficient, the actual peripheral speed in the region of the center of the transport roller 10 to eat. As will be readily apparent to those skilled in the art, any other suitable contacting or non-contact measurement methods may be used in accordance with the invention.

The following is based on the 1 first described a regulatory procedure. In the knowledge of the prevailing withdrawal speed of the glass tubing 2 and the respective actual peripheral speed of the transport rollers R1-R8, the rotational speed of the drive motors M1-M8 is controlled such that the difference between the actual take-off speed in the region of the respective associated transport roller R1-R8 and the actual peripheral speed of the respective associated transport roller R1-R8 to one Zero value is controlled or to a value that is less than a predetermined threshold regulated. This can effectively slip the glass tubing 2 be prevented at the respective transport role. As stated above, by means of the coupling device 7 several of the transport rollers R1-R8 are combined into subgroups whose respective peripheral speeds are regulated accordingly, wherein the control is then regulated in each case to a predetermined transport role of the respective group of transport rollers.

The following is based on the 1 and 3 A control method according to the present invention is described. According to the 3 the speed of a transport roller R is determined by the speed of the motor M. For this purpose, a control value ω _{soll of} a calculation unit assigned to the engine M is first of all determined by the central control device 9 entered. The calculation unit 9 modifies the size of this input value, for example in the form of a correction quantity, which is given to the control variable. In the calculation of this correction value are various process parameters, in particular at least one of the following variables: measured actual withdrawal speed v _is the glass tube strand, temperature in the range of the transport roller R, outer radius of the transport roller R, position of a support point on a support surface of the transport roller R (see. 2a to 2c ), Coefficient of linear expansion of the glass material of the glass tube strand, position of the transport roller R along a drawing path for drawing off the glass tube strand.

For example, the temperature in the region of the first transport roller R1 (cf. 1 ) by means of a temperature sensor T1 and the temperature in the region of further transport rollers, in particular the rearmost transport roller R8, are determined by means of further temperature sensors, for the last transport roller R8, for example with the aid of the temperature sensor TS2. From this or from the werteren measured temperatures, the central control device 8th determine and interpolate the temperature profile along the draw paths formed by the transport rollers R1-R8. With knowledge of the material properties of the glass tubing, in particular the coefficient of thermal expansion of the glass material of the glass tubing, the central control device 8th from this the thermally induced length contraction of the glass tube rod 2 and thus the actual take-off speed prevailing in the region of a respective transport roller as well as the actual outer diameter of the glass tube strand 2 to calculate. This can then be the central control device 8th for each of the transport rollers R1-R8, calculate a respective correction value for the actual rotational speed of the respective drive motor M1-M8 to appropriately control the actual rotational speed of the respective drive motor M1-M8. Thus, even without elaborate control according to the invention the prevailing process parameters are sufficiently taken into account. In this case, as in the above-described control method, by means of the coupling device 7 some of the transport rollers R1-R8 are subdivided into groups of transport rollers whose peripheral speeds are then respectively controlled in a corresponding manner.

As will be readily apparent to one skilled in the art, the very essence of a control device according to the invention is a corresponding speed control or speed control, so that the appended claims also include a corresponding computer program product, particularly in the form of a suitable software program. Although it has been described above that the glass tube strand is manufactured by a vello method, the control method according to the present invention can be similarly applied to a Danner method or a down-draw method.

LIST OF REFERENCE NUMBERS

1

Glass tube manufacturing plant

2

glass tube

3

plastically deformable glass tube

4

die

5

off device

6

drive motor

7

coupling device

8th

central control or regulating device

9

computer unit

10

role

11

wedge-shaped bearing surface

12

support point

13

support point

14

contact point

15

contact point

16

measuring roller

17

measuring roller

18

measuring range

19

measuring range

20

imaging optics

21

Image capture device / camera / position sensor

22

Image capture device / camera / position sensor

23

Image capture device / position and / or speed sensor

24

Image capture device / position and / or speed sensor

R, R1-R8

role

RR, RR '

effective radius

V _is

Is speed

ω _should

Target angular velocity

M, M1-M8

drive motor

C, C1-C8

Control signal

VS, VS1-VS9

speed sensor

V, V1-V9

observation volume

TS1 TS2

temperature sensor

Claims (25)

Method for controlling the peripheral speeds of transport rollers (R) of a glass tube manufacturing plant ( 1 ) used to pull off a hot glass tube strand ( 2 ) a plurality of transport rollers (R) to which one or more drive means (M) for driving the respective associated transport roller (R) or transport rollers (R) is or are assigned, and in the withdrawal direction of the glass tube strand ( 2 ) downstream take-off device ( 5 ) for removing the glass tube strand ( 2 ) at a predetermined speed, wherein at least one transport roller (R) is associated with a non-contact speed sensor (VS), which is an actual take-off speed (v _ist ) of the glass tubing string ( 2 ) in the region of the respectively assigned transport roller (R), in which method the measured actual withdrawal speed (v _ist ) of the glass tube strand ( 2 ) of a control device ( 8th . 9 ) and the control device ( 8th . 9 ) controls or regulates the peripheral speed of the at least one transport roller (R) in order to minimize or control a difference between the actual take-off speed (v _ist ) in the region of the respective associated transport roller (R) and the peripheral speed of the respective associated transport roller (R) , The method of claim 1, wherein the peripheral speed of the respective associated transport roller (R) is measured. Method according to claim 2, wherein the transport rollers (R) each have wedge-shaped bearing surfaces ( 11 ) and the peripheral speed of the respective associated transport roller (R) in the region of at least one support point ( 12 . 13 ) of the glass tubing string ( 2 ) on the wedge-shaped bearing surface ( 11 ) or at the respective point of support ( 12 . 13 ) corresponding investment or measurement point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Method according to claim 3, wherein the respective contact point ( 12 . 13 ) of the glass tubing string ( 2 ) on the respective bearing surface ( 11 ) is detected optically and the peripheral speed of the respective associated transport roller (R) at the thus detected respective contact point ( 12 . 13 ) or at a corresponding investment or measuring point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Method according to claim 4, wherein the position of a measuring area on the support surface ( 11 ), at which the circumferential speed of the respective associated transport roller (R) is measured, is varied so that the circumferential speed of the respective associated transport roller at the respective contact point thus detected (FIG. 12 . 13 ) or at a corresponding investment or measuring point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Method according to one of claims 2 to 5, wherein the peripheral speed of each associated transport roller (R) contactless by means of a laser Doppler measurement method or touching by means of at least one speed measuring roller contacting the respective transport roller (R) ( 16 . 17 ) is measured. Method according to one of claims 2 to 6, wherein the control device ( 8th ) outputs a control variable (C) to the respective drive means (M) as a function of the respectively measured peripheral speed, so that the difference between the actual measured take-off speed (v _ist ) in the region of the respective assigned transport roller (R) and the peripheral speed of the respective associated Transport roller (R) is controlled to a zero value. Method according to one of claims 2 to 6, wherein the control device ( 9 ) a control variable (C) or a correction value for a control variable (C) is calculated as a function of at least one of the following variables: measured actual withdrawal speed (v _ist ) of the glass tube strand ( 2 ), Temperature (T) in the region of the respective associated transport roller (R), outer radius of the respective associated transport roller (R), position of a contact point ( 12 . 13 ) on a support surface ( 11 ) of the respective associated transport roller (R), coefficient of linear expansion of the glass material of the glass tube strand, position of the respective associated transport roller (R) along a drawing path for removing the glass tube strand ( 2 ); and wherein the control quantity (C) thus calculated is output to the respective drive means (M) in order to control the peripheral speed of the respective associated transport roller (R) or transport rollers (R). Method according to one of the preceding claims, wherein the plurality of transport rollers (R) by means of at least one coupling device ( 7 ) is divided into a series of groups of transport rollers, the respective peripheral speed of which is regulated or controlled in groups according to the respective control variable (C). Method according to one of the preceding claims, wherein the plurality of transport rollers (R) are arranged in a region in which the temperature of the glass tube strand ( 2 ) above a solidification temperature of a glass material of the glass tubing, preferably above 400 ° C and more preferably above 350 ° C. Method according to one of the preceding claims, wherein the temperature of the glass tube strand ( 2 ) is measured at least at a first transport roller (R1) of the plurality of transport rollers (R1-R8) and a transport roller (R7), wherein the temperature of the glass tube strand is cooled at least to the solidification temperature of the glass material of the glass tube strand, and the peripheral speeds of Transport rollers according to a thermal length contraction of the glass tube strand ( 2 ) and the respective position of those transport rollers (R1, R7), in which the temperature of the glass tube strand ( 2 ) was measured, controlled or regulated. Use of a method according to one of the preceding claims in the manufacture of glass tubes by pulling off a glass tube strand ( 2 ), in particular a die ( 4 ) or a Danner pipe of the glass tube manufacturing plant ( 1 ), for controlling the peripheral speeds of a plurality of transport rollers (R) of the glass tube manufacturing plant ( 1 ). Computer program product comprising software code sections to provide a method of controlling the peripheral speeds of a plurality of transport rollers (R) of a glass tube manufacturing plant ( 1 ) according to any one of claims 1 to 11, when applied to a processor of a control device ( 8th . 9 ) of the glass tube manufacturing plant ( 1 ) is performed. Apparatus for controlling the peripheral speeds of transport rollers (R) of a glass tube manufacturing plant ( 1 ) for removing a hot glass tube strand ( 2 ) a plurality of transport rollers (R) to which one or more drive means (M) for driving the respective associated transport roller (R) or transport rollers (R) is or are assigned, and in the withdrawal direction of the glass tube strand ( 2 ) downstream take-off device ( 5 ) for removing the glass tube strand ( 2 ) at a predetermined speed, wherein at least one transport roller (R) is associated with a non-contact speed sensor (VS), which is an actual take-off speed (v _ist ) of the glass tubing string ( 2 ) in the region of the respective associated transport roller (R), characterized by a control or regulating device ( 8th . 9 ), which is based on the measured actual take-off speed (v _ist ) of the glass tubing string ( 2 ) controls or regulates the peripheral speed of the at least one transport roller (R) in order to minimize or control a difference between the actual take-off speed (v _ist ) in the region of the respective associated transport roller (R) and the peripheral speed of the respective associated transport roller (R) , Apparatus according to claim 14, further comprising at least one speed sensor (VS) for measuring the peripheral speed of the respective associated transport roller (R). Apparatus according to claim 15, wherein the transport rollers (R) each wedge-shaped bearing surfaces ( 11 ) and the respective speed sensor (VS) is positioned or by means of a associated evaluation device is evaluated so that the peripheral speed of each associated transport roller (R) in the range of at least one support point ( 12 . 13 ) of the glass tubing string ( 2 ) on the wedge-shaped bearing surface ( 11 ) or at the respective point of support ( 12 . 13 ) corresponding investment or measurement point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Apparatus according to claim 16, further comprising at least one optical measuring device ( 21 , 24 ), which is designed or evaluated by means of an associated evaluation device, that the respective contact point ( 12 . 13 ) of the glass tubing string ( 2 ) on the respective bearing surface ( 11 ) is detected optically and the peripheral speed of the respective associated transport roller (R) at the thus detected respective contact point ( 12 . 13 ) or at a corresponding investment or measuring point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Apparatus according to claim 17, further comprising an adjusting device which is designed to determine the position of a measuring area on the support surface (10). 11 ), at which the circumferential speed of the respective associated transport roller (R) is measured, to be varied such that the circumferential speed of the respective associated transport roller at the respective contact point thus detected (FIG. 12 . 13 ) or at a corresponding investment or measuring point ( 14 . 15 . 18 . 19 ) is measured at the same peripheral speed. Device according to one of claims 15 to 18, further comprising a laser Doppler velocimeter in order to measure the peripheral speed of the respective associated transport roller (R) without contact by means of a laser Doppler measuring method, or at least one speed measuring roller ( 16 . 17 ), which contacts the respective transport roller (R) in order to measure the peripheral speed of the respective associated transport roller (R). Device according to one of claims 15 to 19, wherein the control or regulating device as a control device ( 8th ) is designed so as to output a control variable (C) as a function of the respectively measured peripheral speed, so that the difference between the actually measured take-off speed (v _ist ) in the region of the respectively assigned transport roller (R) and the peripheral speed of the respectively assigned transport roller ( R) is controlled to a zero value. Device according to one of claims 15 to 19, wherein the control or regulating device as a control device ( 9 ) is designed to calculate a control quantity (C) or a correction value for a control variable (C) as a function of at least one of the following variables: measured actual withdrawal speed (v _ist ) of the glass tube strand ( 2 ), Temperature (T) in the region of the respective associated transport roller (R), outer radius of the respective associated transport roller (R), position of a contact point ( 12 . 13 ) on a support surface ( 11 ) of the respective associated transport roller (R), coefficient of linear expansion of the glass material of the glass tube strand, position of the respective associated transport roller (R) along a drawing path for removing the glass tube strand ( 2 ); and to output the control quantity (C) calculated in this way to the respective drive means (M) in order to control the peripheral speed of the respective associated transport roller (R) or transport rollers (R). Device according to one of claims 14 to 21, further comprising at least one coupling device ( 7 ) arranged to divide the plurality of transport rollers (R) into a series of groups of transport rollers whose respective peripheral speeds are controlled in groups in accordance with the respective control or control quantity (C). Device according to one of claims 14 to 22, wherein the plurality of transport rollers (R) are arranged in a region in which the temperature of the glass tube strand ( 2 ) above a solidification temperature of a glass material of the glass tubing, preferably above 400 ° C and more preferably above 350 ° C. Device according to one of claims 14 to 23, further comprising at least a first temperature sensor (TS1) to the temperature of the glass tube strand ( 2 ) at a first transport roller (R1) of the plurality of transport rollers (R1-R8), and a second temperature sensor (TS2) located at a position along a drawing path of the glassmaking machine ( 1 ) is arranged to the temperature of the glass tube strand ( 2 ) at a transport roller (R7), in which the temperature of the glass tube strand has cooled at least to the solidification temperature of the glass material of the glass tube strand, wherein the control or regulating device ( 8th . 9 ) is further adapted to the peripheral speeds of the transport rollers according to a thermal length contraction of the glass tube strand ( 2 ) and the respective position of those transport rollers (R1, R7) to control or regulate the temperatures of the glass tube strand ( 2 ) were measured. Use of a device according to one of the preceding claims in a glass tube manufacturing plant ( 1 ) for the production of glass tubes by pulling off a glass tube strand ( 2 ) especially from a die ( 4 ) or a Danner pipe of the glass tube manufacturing plant ( 1 ), for controlling the peripheral speeds of a plurality of transport rollers (R) of the glass tube manufacturing plant ( 1 ).

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