EP0397656B1 - Process and device for manufacturing tubes with helically arranged seams - Google Patents

Abstract

PCT No. PCT/AT88/00100 Sec. 371 Date Jun. 5, 1990 Sec. 102(e) Date Jun. 5, 1990 PCT Filed Nov. 23, 1988 PCT Pub. No. WO89/05201 PCT Pub. Date Jun. 15, 1989.Disclosed is a process and apparatus for producing helically-seamed pipes of any cross-sectional shape. The pipe is produced from a flat strip of material marked at intervals that are a derivative of the circumference of the pipe. At least two sensors are arranged at check points along a paraxial line in order to identify any deviation of the marks from the axis and to generate mark-recognition signals. If the signals are emitted simultaneously, the circumference is constant, and if there is a time differential between the signals, correction is needed.

Description

The invention relates to a method for producing a screw seam tube from a flat strip of material, which is fed at an angle to the tube, is provided with markings and is wound, any deviation from the desired value of the circumferential length due to changing positional relationships between the markings being recognizable, so that a corrective measure is initiated can be.

In the case of helical, core-free winding of tubes from a material strip, the longitudinal edges of which are continuously connected to one another, problems can arise with regard to the dimensional accuracy of the tube diameter. These problems sometimes occur when determining the cross-sectional area of the first winding, which is generally bent by hand, with a section of the material strip corresponding to the circumferential length of the desired tube being passed through the connecting rollers of the winding system, bent into a loop and started again at the beginning Bending or connecting rollers is fed. It is difficult to precisely determine the pipe diameter, since the first hand-bent loop rarely has a circular cross-sectional area for cylindrical pipes and the desired angular cross-sectional area for square pipes.

However, maintaining the desired circumferential length also presents considerable difficulties. If the longitudinal edges are folded, for example, one longitudinal edge can be provided with a folded web and the other with a U-shaped fold, which are guided into one another, the connecting rollers folding over and pressing the fold. With conventional sheet metal strips, this leads to an offset between 0.7 and 1.3 mm per winding. A number of possibilities have already been proposed for rectifying these errors in cylindrical tubes. For example, positional relationships of markings are controlled (US-A-4 287 739, US-A-2 301 092 and JP-A-58/192617).

According to US-A-4,287,739, a sheet metal strip is provided with a series of markings on each edge, each of which has the same, arbitrarily selected distance from one another. When the tape is being wound, the distance between a marking of one edge and a marking of the other edge of the preceding winding should not change while the circumferential length remains the same. It is not immediately apparent whether the constant circumferential length corresponds to the desired circumferential length. Resulting changes in the distance are recognized by the operating personnel, after which suitable corrective measures can be taken.

US-A-2,301,092 and JP-A-58/192617 also use two rows of markings at equal, arbitrarily selectable intervals, whereby the additional criterion is given here that the distance of the desired circumferential length from each marker on the one side of the tape is marked on the other side of the tape. When winding, the markings of one edge coincide with the markings of the other edge of the previous winding only if the circumferential length corresponds to the desired circumferential length and remains constant. Here, too, changes are recognized by the operating personnel, so that corrections can be made. The attachment and comparison of adjacent edge markings when folding the windings is problematic, since the markings can be made unrecognizable by the fold formation on the one hand and on the other hand can shift for the reasons mentioned at the outset without actually changing the circumference.

US-A-3,217,402 uses essentially the same method. Here, too, the markings of the two rows are spaced apart by the circumferential length, but the constant distances between the markings in each row correspond to a size resulting from the circumferential length, taking into account the tape feed angle. This makes it possible to provide the two band edges with teeth which interlock when winding, the toothed screw seam being welded. Changes in circumference are excluded by the toothing, but a toothing device must be assigned to both edges of the belt, and the use of the winding method is not possible with folded tubes.

In the process known from DE-A-3 324 463 for the production of cylindrical tubes, supporting rollers are provided in the interior of the winding that is formed, which contain pressure load cells. Reducing the circumference increases the pressure acting on the rollers and increasing the circumference reduces the pressure. An electronic control unit is used to compare the measured pressure values with a desired value corresponding to the desired circumferential length and to change the pressure of the bending rollers. Other known corrective measures in the coreless production of cylindrical screw seam tubes relate, for example, to changes in the band edge bending (DE-A-3 137 858) or changes in the feed angle (DE-A-3 500 615).

DE-B-2832508 describes a device for the production of pipes which are to have axially parallel longitudinal rows of holes on part of the circumference which are used for directed air outlet. Since the perforation of the flat strip of material leads to displacements of the holes in view of the inevitable changes in circumference, so that the holes do not lie in the generatrices of the tube but, for example, in helical lines, it is proposed to use a perforated template at the beginning of the tube to be arranged in the form of a ring and to determine the arrangement of the holes with each revolution by means of a scanner which moves in the longitudinal direction of the tube. The signals generated cause the flat strip to be punched. This procedure does not ensure the constancy of the circumferential length, but only prevents the errors per winding from accumulating. A row of holes with exactly the same axis results if the error per winding remains constant. If the error fluctuates, there are only slight deviations, so that the air outlet directions fluctuate within a small angular range.

US-A-3,739,459 describes a method for producing columns with longitudinal stiffening ribs, in which a parallelogram-shaped metal plate with transverse ribs is wound and welded along the seam. Exact circumference control is easily possible since the ribs on the column are aligned. In this winding process, too, the positional relationship between two markings on the abutting edges is checked, so that essentially the same process as in US-A-2301092 and JP-A-58/192617 is used.

The invention has now set itself the task of simplifying a method of the type mentioned, and in particular also to enable the production of screw seam tubes with any cross-sectional shape. According to the invention, this is now achieved in that a single row of markings is made on the material strip at intervals which correspond to the tube circumference, which is increased depending on the angle, and which lie on the resulting tube in at least one axially parallel alignment line if the circumferential length of each winding corresponds to the circumferential setpoint that each mark is moved through a stationary test field associated with the resulting pipe, which generates a mark detection signal, and that each time difference between a setpoint and a setpoint Marker detection signals are used to initiate a corrective action.

Changes are thus determined by monitoring the direct positional relationship between a stationary test facility and the markings passing through it.

The escape line can also be checked several times within a circumferential length. This has the advantage that deviations are recognized more quickly and corrective measures have a more immediate effect.

The method according to the invention is therefore suitable both for cylindrical tubes and for square tubes. In the case of the latter, by dividing the circumferential length into the corresponding side length, the stocks between the markings can also be adapted to the side lengths, so that their constancy can also be monitored individually. As mentioned, the corrective measures can be of any type, for example, to a change in the bending roll pressure, to a change in the angle between the strip inlet plane and the pipe axis, to a constriction of the strip inlet in the plane, and in the case of fold seams to a change in the fold former.

Each corrective measure can start from a zero or middle position corresponding to the target value, so that one Changing the circumferential length must result in either a positive or a negative corrective measure. This may complicate or complicate the design and / or control of the correction means. For example, a rotation of actuators would require their right and left drive.

A preferred embodiment of the method therefore provides that the pipe is wound with a circumferential length that differs from the nominal value by a tolerance amount, so that the markings only deviate from the escape line on one side, the corrected measures being introduced in each case using the same time differences, so that corrective measures are introduced in each case either too big or too small, which mainly depends on the type of screw seam. Welded screw seams will tend to increase in circumference due to the heating, and with folded seams the change in circumference depends on the formation of the fold; Both reductions and enlargements are known here. If the set nominal value of the circumferential length corresponds to one of the two limit values of the tolerance range, a tube with constant circumference is created at the maximum deviation that does not require correction. The correction means can therefore be arranged in a basic position in the event of the maximum deviation, since a negative adjustment does not occur. If there is no deviation, corrective measures are carried out, and if there is a deviation towards the other limit value, the corrective measures are carried out more intensely. Therefore, only a simple drive is required for the above-mentioned rotation of an actuator, since the change of direction is not necessary. For the detection of the deviation, one can proceed in such a way that a time difference deviating from the nominal value zero is determined between the marking detection signals of two test points of the stationary test field oriented parallel to the axis. If the circumference is constant, the signals occur simultaneously on. However, if there is a time difference between the signals, there is a change in scope. A check of the alignment line of the markings carried out in this way is independent of the length of the circumference, but requires sensitive test instruments in order to record the very small time differences.

The corrective measures can only be carried out in the interval between the marking signals, whereby their duration corresponds to the time difference and thus directly to the change in scope. In the case of corrective measures that change the contact pressure of bending or seaming rolls or their position, a correction period that is only in the interval is not sufficient to achieve the desired success. If only one of the two marking detection signals is present, the correction measure is therefore initiated and is preferably maintained until the next delivery of marking detection signals. If these are then submitted at the same time, the corrective action is canceled. If, on the other hand, there is still an interval, the corrective measure is maintained or reinforced.

Another possibility for executing the method is that a time difference between two marking detection signals of a single test point of the fixed test field deviating from a predefined setpoint value is determined, the predefined setpoint value being determined by the circumferential setpoint value. Here there is a dependency on the circumferential length, but there is no comparison between the signals of two test points; mark detection signals can be generated, for example, by changes in the reflection of light waves hitting the mark. Another possibility is that each mark detection signal is generated by scanning a changed surface texture. The latter can be applied particularly to embossed markings.

To produce a screw seam tube of the type mentioned at the outset, a device is used which is provided with a guide table for the incoming material strip, which has a marking device, with a winding device comprising a pipe guide and, in particular, bending rollers, and with means for introducing corrective measures if the circumferential length increases of the resulting pipe changed. The method according to the invention can be carried out with such a device if the guide table has a device for variably adjusting the distance between the markings, if at least one test device for emitting marking detection signals is arranged in the area of the pipe guide of the winding device and if the detection of changes The circumferential length is provided with a device for determining a time difference between two marking detection signals, to which the means for initiating the corrective measure are assigned.

For the adjustment of the distance between two markings, a sensor that is adjustable along the material strip is preferably provided, which, when a marking is recognized, causes the next marking to be formed by the marking device.

In a preferred embodiment, the test device comprises at least two test points arranged in the region of the pipe guide in an axially parallel alignment line and spaced apart from one another by the width of the material strip. Their arrangement depends on the available space, it is possible both inside or outside the pipe at any circumferential position.

The method according to the invention will now be explained below with reference to the figures in the accompanying drawings, without being limited thereto.

• Fig.1 bis 3 Darstellungen dreier Wickelvorgänge bei der Herstellung von Rohren mit runder Querschnittfläche
• Fig. 4 eine schematische Schrägansicht einer Wickeleinrichtung zur Herstellung von Rohren mit im wesentlichen rechteckiger Querschnittfläche,
• Fig. 5 eine Seitenansicht einer erfindungsgemäßen Vorrichtung,
• Fig. 6 eine Draufsicht auf die Vorrichtung nach Fig. 5,
• Fig. 7 einen Schnitt nach der Linie VII-VII von Fig. 5 oder 6,
• Fig. 8 einen Schnitt nach der Linie VIII-VIII von Fig. 5 oder 6,
• Fig. 9 einen Schnitt nach der Linie IX-IX von Fig. 5,
• Fig. 10 im Schnitt nach der Linie X-X von Fig. 5 oder 6, die Grundstellung zweier Rollen zur Durchführung von Korrekturmaßnahmen,
• Fig.11 und 12 Darstellungen gemäß Fig. 10 in veränderten Stellungen der beiden Rollen, und
• Fig.13 ein Prinzipschaltbild der Steuerung des in den Fig. 10 bis 12 gezeigten Stellmotors.

Show it:

• Fig. 1 to 3 representations of three winding processes in the manufacture of tubes with a round cross-sectional area
• 4 shows a schematic oblique view of a winding device for the production of tubes with an essentially rectangular cross-sectional area,
• 5 shows a side view of a device according to the invention,
• 6 is a plan view of the device of FIG. 5,
• 7 is a section along the line VII-VII of Fig. 5 or 6,
• 8 is a section along the line VIII-VIII of Fig. 5 or 6,
• 9 is a section along the line IX-IX of FIG. 5,
• 10 in section along the line XX of FIG. 5 or 6, the basic position of two roles for implementing corrective measures,
• 11 and 12 representations according to FIG. 10 in changed positions of the two rollers, and
• 13 shows a basic circuit diagram of the control of the servomotor shown in FIGS. 10 to 12.

1 to 3 show the mathematical foundations of the method according to the invention. Assuming that an exactly cylindrical tube 1 is to be wound, its circumferential length is determined according to the equation u = dπ, this size in view of the feed angle α of the material strip 3 to the tube axis, which is dependent on the diameter d of the tube 1 and the width of the material strip 3 5 represents the opposite catheter of a right-angled triangle, the hypotenuse of which corresponds to the distance a between two markings 4. Its length is thus calculated from the formula a = $$\frac{\text{u}}{\text{sin α}}\text{.}$$

In the case of a constant winding, the markings 4 will lie according to FIG. 2 along an alignment line 6 which runs parallel to the tube axis 5. If the circumference of the tube 1 is constantly larger or smaller, the alignment line 6 'no longer runs parallel (FIGS. 1 and 3); changes the change in circumference, there is no alignment line 6, 6 '.

These mathematical foundations are now used in the method according to the invention in the manner shown schematically in FIG. 4 for the production of a tube 1 with an essentially rectangular cross section. A material strip 3 advanced with the aid of the feed and, if necessary, fold forming device 19 shown in FIGS. 5 and 6 is fed to a winding device 10, of which only an inner bending core is shown. At a distance from the winding device 10, which is smaller than the smallest side length of the tube 1 to be produced, a test device 8 is arranged below the material strip 3 or the tube 1, the two test points 9, 9 'in a parallel to the axis 5 of the tube extending escape line 6. If a test device 8 cannot be provided at this point for constructional reasons, then, as shown in FIG. 4, the test device 8 can also be provided laterally outside the pipe 1 at any other point. At a distance, preferably at least corresponding to the circumference, in front of the first test point 9, a marking device 7 is provided, which generates markings 4 from the underside of the material strip 3. The marking device 7 can, for example, contain a punch or embossing stamp, an ink jet nozzle or the like, and is used in each case when a marking 4 that has already been produced passes a sensor of a distance setting device 11 that can be adjusted along the material strip 3 or the first test point 9, so that the distance a between the markings 4 corresponds to a circumferential length or a part of the circumferential length according to the formula given above. Each mark 4 passing the first test point 9 travels around the circumference during the winding of the tube 1 and finally passes a second test point 9 'of the same test device 8. The marking signals of both test points 9, 9' then occur simultaneously, if the circumferential length of the last winding 2 corresponds to the pipe circumference. On the other hand, if the pipe 1 is larger, the first test point 9 will recognize the signal earlier than the second test point 9 ', if the pipe 1 is smaller, the first test point 9 will recognize a signal later than the second. The test device 8 can, for example, emit a light beam at each test point 9, 9 'which, if the marking 4 is formed by a hole, is not reflected when passing through the hole, or, if the marking 4 forms a color spot, is reflected less strongly. If the marking 4 is embossed, a change in reflection can also be recognized here, but here it is also possible to scan the surface of the material strip 3 and to feel the embossing.

Particularly in the case of a tube 1 with an angular cross-sectional area, not only the monitoring of the constancy of the circumference, but also the constancy of the side lengths may be necessary in order to produce torsion-free square tubes. Especially for this case, several test devices 8 can be provided distributed as shown. Here, the markings 4 then pass through several first test points 9 and finally several second test points 9 'per winding 2, wherein deviations can be identified in each case from a time difference. If, as mentioned, the distances between the markings 4 are reduced and the circumferential distances of the test devices 8 are matched, the signals of several test devices 8 can also be compared with regard to their simultaneity and evaluated for corrective measures. In particular in the case of a multiple test per circumferential length, there is the possibility shown to assign the setting device 11 one or more further sensors for detecting the markings 4.

5 and 6, a device is shown, which in turn is intended for winding round tubes, which by means of of a fold. The material strip 3 drawn off a reel passes through a feed and fold forming device 19, in which the metal strip 3 receives the edge shaping which can be seen in FIGS. 7 and 8. Following the fold forming device 19, the material strip 3 runs between guide plates 15 of a guide piece 18. A guide track 12 extends parallel to the guide plates 15, on which the marking device 7 is provided. According to FIG. 7, this has an embossing stamp 16 which engages on the underside of the material strip 3 and is actuated by an electromagnet 17 via a lever transmission.

At the other end of the guideway 12, the inventory adjustment device 11 is arranged, which has a sensor for detecting the markings 4 (FIG. 8). The stock a between the marking device 7 and the stock setting direction 11 can be changed and is calculated from the circumferential length u in accordance with the formula given above.

A pair of rollers 2o is arranged between the distance adjusting device 11 and the winding device 1o as a means 13 for correcting deviations in the calculated circumferential length u. As can be seen in more detail from FIGS. 1o to 12, the two rollers 2o are rotatably mounted on a holder, and cover the longitudinal edge region bent in the fold forming device 19, next to which the markings 4 are embossed, and that in the closed fold according to FIG. 9 internal fold strips 26 includes. The longitudinal edge area is therefore first offset by dimension B and the subsequent fold strip is folded down. The upper roller 2o is mounted in a carrier 21 which is arranged on a threaded spindle driven by a servomotor 22 mounted on the holder, so that the dimension B between the rollers 2o can be changed via the servomotor 22.

The material strip entering the winding device 10 is formed there by the bending and folding closing rollers 14, and is folded, as can be seen from FIG. 9. According to FIG. 13, electronics 25 provided with a freely programmable controller 24 processes the signals emitted by the test stations 9, 9 'and controls the servomotor 22, which changes the distance B between the rollers 2o according to FIGS. 1o to 12, whereby in the position according to FIG. 10 a tube with the smallest diameter and in the position according to FIG. 12 a tube with the largest diameter is formed since the distance of the edge region carrying the folded strip 26 to the axis 5 of the non-centrally guided tube is changed.

A pipe 1 folded according to FIG. 9 tends to enlarge its diameter, so that a shape exaggerated in FIG. 1 would result. If the tube 1 is now wound with a circumferential length that is reduced by the tolerance value from the nominal value, the markings 4 deviate only on one side from an axially parallel alignment line, in which they lie only with maximum automatic enlargement. In this case, dimension B is set to a maximum (Fig. 1o). If the test station 9, 9 'detects an insufficient magnification due to a deviation, the control motor 22 and the electronics 25 set the actuator 22 in motion, which reduces the dimension B, the reduction corresponding to the time difference between the marker detection signals increases. A slight time difference will, for example, bring about a slight reduction in dimension B, as shown in FIG. 11, while a maximum time difference will result in the edge strip according to FIG. 12 being completely pushed through. Thus, the attempt to enlarge the tube 1, which is set too small, is always supported to the extent that leads to the desired extent due to time differences in the marking detection signals. The currently set Dimension B between the rollers 2o remains unchanged when the next signal pair is supplied to the electronics 25 at the same time, but a further adjustment takes place in the case of time differences. By assigning the basic position of the rollers 2o shown in FIG. 1o to a limit value of the increasing deviations of a pipe that is too small, there is basically only the need to enlarge the pipe diameter, with which a simple actuator can be achieved. A corrective measure consisting in a reduction in dimension B therefore always moves in a positive range, which begins with the basic position shown in FIG. 10, but it never has to be reversed.

But it can also be found with a test station 9, which then carries out a comparison between a predetermined target value, which is dependent on the circumferential length and the feed rate, of the time difference between two marking detection signals and their actual value. This method can also be used at several test centers 9, 9 ', or can be superimposed on the method described above.

Claims (11)

1. A process for the production of a spiral seam tube (1) from a flat strip (3) of material which is fed at an angle to the tube (1), provided with markings and coiled, wherein any deviation from the reference value in respect of peripheral length can be detected by varying positional relationships between the markings (4) so that a correction step can be initiated, characterised in that a single row of markings (4) is provided on the strip of material (3) at spacings (a) which correspond to the periphery (u) of the tube, which is increased in dependence on angle, the markings on the resulting tube (1) being in at least one alignment line (6) rich is parallel to the axis of the tube when the peripheral length of each turn corresponds to the reference value of the periphery, that each marking (4) is moved through a stationary testing area rich is associated with the resulting tube (1) and rich produces a marking detection signal, and that any time difference rich deviates from a reference value, between two marking detection signals, is used for initiating a correction step.

2. A process according to claim 1 characterised in that the tube (1) is coiled with a peripheral length rich differs from the reference value of the periphery by a tolerance amount so that markings (4) only deviate at one side from the alignment line (6), wherein only correction steps which are respectively effective in the same direction are initiated by the detected time differences.

3. A process according to claim 1 or claim 2 characterised by ascertaining a time difference which deviates from the reference value of zero, between the marking detection signals of two test locations (9, 9′) of the stationary testing area ( 8 ), said test locations being oriented in parallel relationship with the axis of the tube.

4. A process according to claim 1 or claim 2 characterised by ascertaining a time difference which deviates from a predetermined reference value, between two marking detection signals of a single test location (9) of the stationary testing area, wherein the predetermined reference value is defined by the reference value in respect of the periphery.

5. A process according to claim 3 or claim 4 characterised in that each marking detection signal is produced by scanning of an altered surface characteristic.

6. A process according to claim 3 or claim 4 characterised in that each marking detection signal is produced by a change in reflection of light waves impinging on the marking (4).

7. A process according to claim 1 characterised in that the strip of material (3) is embossed, perforated or marked in colour.

8. Apparatus for carrying out the process according to claim 1 comprising a guide table (18) for the incoming strip of material (3), which guide table has a marking means (7), a coiling means (10) including a tube guide and in particular bending rollers (14), and means (13) for initiating correction steps if the peripheral length (u) of the resulting tube (1) alters, characterised in that the guide table (18) has a means (11) for variably setting the spacing (a) between the markings (4), that at least one testing means (8) for the output of marking detection signals is arranged in the region of the tube guide of the coiling means (10), and that for detection of changes in the peripheral length (u) there is provided a means (24, 25) for ascertaining a time difference between two marking detection signals, with which means the means ( 13 ) for initiating the correction step are associated.

9. Apparatus according to claim 8 characterised in that the means (11) for setting the spacing between the markings (4) includes a sensor which is displaceable along the strip of material (3) and which, when a marking (4) is detected, causes the production of the next marking (4) by the marking means (7).

10. Apparatus according to claim 8 characterised in that the testing means (8) is provided in the region of the tube guide with at least two testing locations (9, 9′) which are arranged in an alignment line (6) in parallel relationship to the axis and which are spaced from each other by the width of the strip of material (3).

11. Apparatus according to claim 8 characterised in that an embossing punch (16) is provided as the marking means (7).

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