EP1030746A1

EP1030746A1 - Precision-rolling method

Info

Publication number: EP1030746A1
Application number: EP98949818A
Authority: EP
Inventors: Gerald Hein
Original assignee: Voest Alpine Industrienlagenbau GmbH
Current assignee: Primetals Technologies Austria GmbH
Priority date: 1997-11-14
Filing date: 1998-10-21
Publication date: 2000-08-30
Anticipated expiration: 2018-10-21
Also published as: DE59804086D1; WO1999025499A1; US6216517B1; EP1030746B1; JP2001523575A; JP4316796B2; ATA193297A; AT406644B

Abstract

The present invention relates to a precision rolling method intended for producing rolled products (1) in the shape or rods or wires while respecting the shape and size allowances. In order to provide good accessibility to the rolling stands (15, 16), the method of the present invention comprises combining the following properties: rolling the product to be rolled (1) in at least one dual rolling stand (15) with an open pass (5) starting from any cross section in order to produce a rolled product (1) with a polygonal and essentially tetragonal cross section; and guiding the rolled product (1) into another rolling stand (16) following a path of a predetermined length along one or more longitudinal edges and/or along the surfaces of said product (1) which are adjacent to the longitudinal edges, and subsequently rolling the same so as to obtain a rolled product (1) with a round cross section in at least one closed pass (6). During the rolling process, the rolling forces are applied in the form of a star from at least three direction so as to deform the rolled product (1).

Description

Precision rolling process

The invention relates to a precision rolling process for the production of rod-shaped or wire-shaped rolling stock with a circular cross-section, while observing narrow shape and dimensional tolerances, and a profile rolling device for carrying out the method.

Several systems are currently known for the precision rolling ("sizing") of rod-shaped rolling stock. The known systems are used after continuous bar steel rolling mills or before or after wire rolling blocks in order to improve the dimensional and dimensional stability of the rolling stock.

A known system consists of three duo mill stands in the sequence horizontal-vertical-horizontal. The round running out of the continuous rolling mill is formed in this system with the oval-oval-round caliber sequence with a low degree of forming to the desired finished dimension.

The disadvantages of this system are as follows: The oval cross sections are difficult to run with known rolling stock guides. The rolling stock tends to tilt, i.e. for cross-section rotation, especially if the distance between the scaffolding is too large. Therefore, the rolling stock is not guided between the stands and the stand spacing is chosen to be as small as possible. This results in the further disadvantage that, in the event of a malfunction in the rolling stock flow, the accumulated rolling stock can only be removed with difficulty. The maintenance of the scaffolding is also complicated and cumbersome. A third disadvantage is the very complicated dimensional adjustment of the rolling calibers to the finished dimension due to the need to take bearing play into account and the thermal expansion of the stands during operation.

Another system consists of two duo stands in the sequence vertical-horizontal, the second stand having pre-tensioned rollers. Here, too, the round emerging from the continuous rolling mill is shaped to the desired finished size using the oval-round caliber sequence. The pre-tensioned rollers of the finishing stand compensate for the bearing play and the thermal stand expansion. Here too there is the decisive disadvantage of the difficult guiding of the oval cross-section into the round caliber.

A third system consists of a roll block with three roll stands, in each of which three rolls are arranged at 120 ° to each other. The round running out of the continuous rolling mill is trigon-trigon-round to the desired finished size with the caliber sequence reshaped. The disadvantages lie on the one hand in the high mechanical outlay for driving and synchronizing the three rollers per stand, on the other hand in the fact that no compensation for the bearing clearances and thermal expansion of the stands is ensured.

The fourth known system consists of two roll stands, each with four rolls, of which only one pair of rolls is driven and the other is carried along by the rolling stock. The roll axes of the second roll stand are rotated by 45 ° with respect to the first. This system also has the disadvantage of difficult presetting of the roll calibers, since the bearing clearances and thermal expansions have to be taken into account. Further disadvantages result from the drive position of the second stand rotated by 45 °, which requires a complicated mechanical drive. Another disadvantage is that the non-driven roller pairs have to be accelerated from the incoming rolling stock to their working speed, which can result in damage to the base of the caliber.

The invention aims to avoid these disadvantages and difficulties and has as its object to provide a precision rolling method for producing rod-shaped rolling stock or wire with a circular cross-section, which result in rolling stock with particularly high accuracy in a certain dimension, but nevertheless - in contrast to State of the art - there is good accessibility to each of the roll stands, so that even in the event of a fault, the rolling can be continued again within a short time, ie the operational readiness of the system can be restored as quickly as possible and simple maintenance is possible.

In a method of the type described in the introduction, this object is achieved by combining the following features:

Rolling the rolling stock in at least one duo rolling stand with an open caliber, starting from any cross-section to a rolling stock with a polygonal, in particular, tetragonal cross-section,

Guiding the rolling stock over a predetermined path length along one or more longitudinal edges and / or along the surfaces of the rolling stock adjoining the longitudinal edges to a further rolling stand and

• subsequent rolling into a rolling stock with a circular cross section in at least one closed caliber, in which rolling forces act in a star shape on the rolling stock from at least three directions and deform the rolling stock. By guiding the bar steel to introduce it into the further roll stand, which is made possible by the polygonal cross section of the bar steel emerging from the duo roll stand, an exact constant feeding of the same into the further roll stand is ensured along the entire length of the bar stand, so that both a uniform deformation of the steel bar and, as a result, a uniform cross-section can be achieved, and due to the uniform deformation, no tilting or the like takes place even after the steel bar exits the roll stand.

The rolling stock is preferably rolled in two duo rolling stands arranged one behind the other to form a rolling stock with a tetragonal cross section and guided between these two duo rolling stands.

A profile rolling device for carrying out the method according to the invention is characterized by:

At least one duo roll stand with an open, polygonal, in particular tetragonal, roll caliber,

• a rolling stock routing to the duo rolling stand in the rolling direction with the rolling stock emerging from the duo rolling stand on one or more longitudinal edges and / or on the surfaces of the rolling stock leading to the longitudinal edges of the rolling stock and

• at least one further roll stand with a closed circular caliber with at least three rollers arranged in a star shape.

A rolling stand with a closed caliber is known for example from DE-A-1 527 722. It has four disks, the work surfaces of which form a closed caliber. Two opposite disc rollers are driven, whereas the other two disc rollers are moved over the material to be rolled. The disc rollers can be adjusted against each other so that the size of the caliber is variable. Each disc roller is acted upon by a different disc roller, a displacement of the disc rollers in the radial direction of the other disc rollers making this change in caliber possible. However, this means that the disc rollers can only be held against one another with relatively small forces, since no counterforces can be applied to avoid bending the disc rollers. Such a closed caliber is already difficult to form a closed caliber permanently without the additional force caused by rolling, but rather an undesirable change in dimension of the caliber occurs, so that the desired dimensioning of a rolling stock is not achieved can. A particularly advantageous embodiment according to the invention is characterized in that two duo mill stands with a tetragonal roll caliber are provided with an intermediate guide.

According to a preferred embodiment, according to the invention, the rollers of the further roll stand are supported against one another via conical surfaces for simple implementation of a caliber which is always closed even under difficult rolling conditions, the rollers being pressed against one another with an adjusting force which exceeds the rolling force by a pretensioning force.

A rolling stand with a closed caliber of the type described above is known per se, for example from EP-A-0 264 849.

According to the invention, the closed caliber preferably has a cross-sectional area that is 5 to 20% smaller than that of the open caliber of the duo mill stand. As a result, even steel alloys with high resistance to deformation can be rolled particularly precisely, and high rolling speeds can also be achieved on account of the low rolling forces that result.

A preferred embodiment is characterized in that the further roll stand has four rollers, in particular disc rollers, of which only two rollers lying opposite one another can be driven by means of a motor, in particular with a common motor, and that each of the four rollers has a conical surface in each case abuts a conical surface of a further roller, each roller abutting two adjacent rollers and a closed power flow and a friction drive for the rollers not driven by a motor being established via the conical contact surfaces of the rollers.

This results in a particularly advantageous frictional connection within the caliber, with the division of the drive, on the one hand, as a forced drive via a motor and, on the other hand, via the conical surfaces, achieving synchronization of the rollers with the simplest of means. The disc rollers ensure that the stress on the shaping surfaces of the rollers can be kept lower due to the larger circumference.

The driven rollers of the further roll stand advantageously have a larger diameter in the shaping surfaces than the rolls which are not driven by their own drive, as a result of which the bar steels are particularly easy to insert into the further roll stand can be initiated so that the desired cross section is obtained particularly quickly in the head region of the steel bar.

According to a further preferred embodiment, the rollers of the further roll stand, which can be driven by a motor, are displaceable in the direction of their shaft against the two further rolls, whereby an exact positioning of the further roll stand with respect to the first and the guide is achieved, so that the axis of the rolling stock in the rolling mill can be maintained in a completely straight line.

The further roll stand advantageously has two stand stands, which are prestressed against one another via tie rods and threaded nuts. As a result, particularly high forces can be applied, so that a reduction in the cross-sectional area of the rolling stock can be achieved with particularly high accuracy, and high speeds can be achieved at the same time. Due to the constructive design with tie rod and threaded nut, a particularly simple design of the scaffold stand can be realized, which is at the same time particularly reliable.

If the threaded nuts are hydraulic nuts, they can be assembled particularly easily, e.g. done without additional tools.

If the duo roll stand and / or the further roll stand are each arranged on a stand change carriage, which can be pushed along rails in a working position and fixed there and pushed again from this position into a rest position, then the rolls can be replaced particularly easily, an exact positioning of the roll stand can be carried out particularly easily at the same time.

The shaping surfaces of the rolls forming the closed caliber expediently have a chamfer on the circular edges which adjoin one another. This ensures an accurate cross-sectional area of the rolling stock, even in the event of irregularities in the cross-sectional area of the rolling stock from the duo rolling stand or non-equalized speeds between the duo rolling stand and the further rolling stand, the stress on the shaping surfaces of the further stand being kept particularly low.

A particularly simple design of the guide devices is characterized by profile rollers. These are expediently arranged in pairs to form a caliber that is adapted to the cross-sectional shape of the rolling stock to be guided. Furthermore, depending on the length of the path, the profile rollers are provided to form a roller conveyor. The invention is explained in more detail below with reference to two exemplary embodiments shown in the drawing, with a caliber sequence for the rolling method according to the invention and the device for carrying out the method being illustrated in FIGS. Fig. 2 shows a schematic representation of two rolling stands arranged one behind the other of the profile rolling device according to the invention. Fig. 3 illustrates a section through the rolling stand along the line III / III of Fig. 2; FIG. 4 shows a section through the rolling stand according to the line IN / IN in FIG. 2, and FIGS. 5a and 5b each illustrate an exemplary embodiment of a guide device between the rolling stands. 6a to 6c show the caliber sequence according to a further embodiment.

The rolling stock 1 to be deformed, a bar steel, is, starting from the round cross-section shown in FIG. 1 a (dash-dotted line in FIG. 1 b) to an essentially square cross-section by means of the rolls 3, 4 shown in FIG. 1 b with grooves 3 a , 4a of a duo mill stand with open caliber 5, while reducing the cross-sectional area. This now square-edged steel bar, which can also have a different polygonal cross section, such as a triangular, pentagonal or the like, comes into the closed caliber 6 shown in Fig. lc with four disc rollers 7, 8 and 9, 10, in which it is rolled again to a steel bar with a round cross-section, but with high precision.

The disc rollers 7 to 10 have conical surfaces on the areas adjoining the caliber partial surfaces 11, 12 and 13, 14, etc. 7a, 7b, 8a, 8b, 9a, 9b and 10a, 10b. These surfaces each include an opening angle α of 90 °, so that the individual disc rollers 7 to 10 can be pressed against each other with the same truncated cone surfaces with the least amount of slip, which on the one hand forms a closed caliber and on the other hand the drive from one pair of disc rollers to the other pair of disc rollers high forces can be performed. As shown in FIG. 1d, the edges between the cone hull surfaces 7a, 7b and the caliber partial surface 11 can be chamfered, so that a caliber is produced which is still closed but has the possibility of avoiding surface pressure peaks.

The closed caliber, which is shown in FIG. 1c, can also have any other shape, for example a square or another polygonal cross section, oval or the like.

In the sequence of the calibres 5 and 6, in the sense of a uniform deformation, care must be taken that the successive rolling passes are not always in the same or analog directions is deformed, but the deformation takes place, for example, normal to the first deformation direction, so that, based on the entire cross section, there are essentially uniform deformations.

In Fig. 2 two rolling stands 15, 16 are shown arranged one behind the other in the rolling direction c, u.zw. a duo mill stand 15 with the open caliber 5 and a four-disk mill stand 16 with the closed caliber 6. For better understanding, both the duo mill stand 15 and the four-disk mill stand 16 are shown in elevation. A rolling stock guide 17 is illustrated in a schematic representation between the roll stands, a detail of which can be seen in FIG. 5a. The roll stands 15 and 16 are each arranged on a stand changing carriage 18 and 19, which can be pushed along rails 20 and 21 from the working position, the standing stands 22, 23, which are also arranged on stand changing carriages 24 and 25, in Working position can be moved. It is only necessary here that rails are also provided parallel to the rolling direction c, so that the carriages 18, 19 can be rotated at the crossing point of the rails running parallel and parallel to the rolling direction c and thus moved out of the rolling position, and the further rolling stand then can be brought back into working position. Such a process is necessary if either a change in the cross section of the steel bar 1 is to be carried out or if the rollers 3, 4 and 7 to 10 are worn and an exchange is required.

Both roll stands 15, 16 have electric motors 26, 27, the speed of which can be precisely regulated, the gear reduction 28, 29 reducing the speed to a lower number of revolutions and in subsequent gears 30 and 31 essentially transmitting the rotary movement from one axis to two axes of the duo mill stand 15 or a pair of rolls of the four-disk mill stand 16.

The control of the drive must take place taking into account the decrease in cross-section in such a way that the same speed of the rolling stock 1 does not occur, but rather the same mass throughput speed in the rolling stands 15, 16, in order to avoid any malfunctions in the rolling process. However, it can also be advantageous that the four-disc rolling mill 16 has a slightly higher rolling speed than would be required for the mass throughput of the duo rolling mill 15, thus reducing the rolling stock between the duo rolling mill 15 and the four-wheel rolling mill 16 slightly Train is exercised, which, as is known, can be avoided more easily. The transmission of force between the transmissions 28 and 30 or 29 and 31 takes place via shafts 32 and 34 or 33 and 35 which are flanged together via flanges and an interposed Hardy disc (not shown). The force is diverted from the transmissions 30 and 31 via shafts 36, 37 and 38, 39 and via universal joints 40, 41, 42 and 43 directly into the shafts of the roll stands 15 and 16.

In Fig. 3, the four-disc rolling stand 16 is shown schematically in section, the force being introduced into the shafts 44 and 45 via flanges 46 and 47. The shafts are supported in roller bearings 48, 49 and 50, 51 by frame stands 62, 63, in which the further disk rollers 9 and 10 are also supported in this way.

The disc rollers 9 and 10 are not driven, but are arranged so as to be displaceable transversely on axes 52 and 53, this transverse displacement being carried out by means of spacer discs 54 and 55 and then also a position fixing of the disc rollers 9 and 10 can be achieved. The disc rollers 9, 10 are also mounted on roller bearings 56, 57.

The disc rollers 7, 8, 9, 10 are kept in mutual contact via their conical surfaces 7a, 7b, 8a, 8b, 9a, 9b, 10a and 10b, the relative position of the disc rollers 7 and 8 to one another due to the rigid arrangement in the rigid roll stand is given, whereas the disc rollers 9 and 10, as can be seen particularly clearly from FIG. 4, are held against one another via tie rods 58, 59 and hydraulic nuts 60 and 61. Four tie rods 58, 59 are provided, etc. two before and two after the area in which the closed caliber 6 is present through the four disk rollers 7 to 10, so that clamping takes place symmetrically on the actual area of the deformation.

The rolling stock guide 17 for rolling stock 1 shown in Fig. 5a is on the one hand height and side adjustable via suitable drives, not shown, and has a guide path oriented in the rolling direction for the rolling stock 1, which is realized by profile rollers 64 arranged one behind the other and in pairs, the one Include caliber 65 corresponding to the cross section of the rolling stock 1 to be guided. The guide device could also be formed by guide surfaces, so that an exact guidance of the steel bar 1 emerging from the duo rolling mill 15 is possible, and the bar steel 1 is inserted into the four-disc rolling mill 16 in a precisely reproducible manner. 5a illustrates an embodiment of profile rolls for an octagonal cross section of the rolling stock 1. The arrangement of a rolling stock guide 17 according to the invention enables the two rolling stands 15 and 16 to be moved further apart without the precision of the rolling being affected by the rolling stand 16. For example, according to the invention, a distance 66 between the roll stands 15 and 16 of 1.5 to 2 m can be realized, whereas without such a guide, the roll stands 15 and 16 would have to be arranged very closely adjacent, for example in the range of half a meter or less. According to the invention, the second roll stand 16 is thus also easily accessible, which considerably simplifies operation and maintenance. In addition, any material jams between the two roll stands can be easily removed.

Despite the relatively large distance 66 between the two roll stands 15 and 16 from one another, the start and end regions of the rolling stock 1 can also be rolled particularly precisely to the desired dimension. It is essential that the rolling stock 1 between the two roll stands 15 and 16 has a polygonal cross-section, because only in this way is it possible for the rolling stock 1 to be guided exactly between these two rolling stands 15 and 16. If the rolling stock 1 had a round, for example a circular cross-section in this area, an exact guidance of the rolling stock would not be possible. Tilting of the rolling stock would have a negative effect, e.g. not only on the guidance of the rolling stock, for example when threading into the further rolling stand 16.

6a, 6b and 6c show the caliber sequence according to a further embodiment of the invention, wherein in a first duo roll stand 15 '(FIG. 6a) with caliber rolls 3', 4 'a rolling stock 1 with a slightly oval cross-section ( unshaded area) hatched to a rolling tetragonal in ^{'substantially} cross-section (area in Fig. 6a is rolled). This first duo roll stand 15 'is arranged horizontally. In a subsequent vertical duo roll stand 15 (FIG. 6b) with the caliber rolls 3, 4, the cross section is reduced to a rolling stock 1 with a likewise tetragonal cross section (hatched area in FIG. 6b), the rolling stock 1 being between the first duo rolling stand 3 ', 4' and the subsequent duo-roll stand 3, 4 is likewise guided by means of a rolling stock guide 17, preferably a guide track with guide rollers 64.

Following the second duo mill stand 15, the rolling stock is rolled in a four-disk mill stand 16 (FIG. 6c) with the caliber rolls 7, 8, 9, 10 to form a rolling stock with a circular cross section of the highest precision. A rolling stock guide 17, preferably also formed by guide rollers 64, is provided between the second duo roll stand 15 and the four-disk roll stand 16. example

Continuous cast billets made of carbon steel, e.g. CIO, with a square cross section of 150 mm side length, are rolled in a stretch caliber mill to a round cross section with a diameter of 22 mm. The bar steels thus formed are then fed to a first duo mill stand 15 '. The cross section in this duo roll stand 15 'is reduced by 28%. This is followed by a further rolling in a second duo stand 15 with a 22% stitch reduction to a tetragonal cross section. The steel bar 1 emerging from the second duo mill stand 15 passes via the guide 17 into the four-disk mill stand 16, in which a circular cross section is produced and a further reduction in the cross section is carried out by 19%. The rollers 3 and 4 of the duo roll stand 15 and the four-disk roll stand 16 have a diameter of 320 cm. The speed of the steel bar 1 emerging from the four-disc mill stand 16 is 15 m / sec.

The tie rods 58, 59 and hydraulic nuts 60, 61 in the four-disc roll stand 16 exert a tension of 20 tons.

Guide roller pairs 64 are used to guide the bar steels 1 between the roll stands 15 and 16, which are arranged approximately 2.5 m apart.

With the method according to the invention, finished products with a circular cross section can be produced with very high precision, etc. both in terms of size and shape, e.g. Finished products in the diameter range up to 25 mm with a minimum tolerance of ± 0.1 mm, and in the diameter range from 25 to 100 mm with a minimum tolerance of ± 0.25% of the diameter.

The method according to the invention and the device according to the invention also enable simplified rolling operation, insofar as the roughing mill upstream of the profile rolling device according to the invention does not require a change in caliber for different diameters of the end product; a change in caliber is only required for the profile rolling device according to the invention, which is given by the possibility of a large variation in the stitch decrease in the diameter range of at least 1: 4 given the profile rolling device according to the invention. It is thus possible to produce a finished product of, for example, 25 to 100 mm from one and the same rolling stock fed to the profile rolling device according to the invention. Furthermore, according to the invention, a finished product with any diameter can be produced, ie the diameter of the end product can be selected continuously; one is not bound to jumps in diameter.

Since the rolling stand 16 can be machined with the closed caliber 6 and the pretensioned rollers 7 to 10 in the closed and pretensioned state, the production of a specific caliber is particularly simple.

Claims

Claims:

1. Precision rolling process for producing rod-shaped or wire-shaped rolling stock (1) with a circular cross-section, while adhering to narrow shape and dimension tolerances, characterized by the combination of the following features:

Rolling the rolling stock (1) in at least one duo roll stand (15, 15 ') with an open caliber (5), starting from any cross section to form a rolling stock (1) with a polygonal, in particular tetragonal cross section,

• Guiding the rolling stock (1) over a predetermined path length along one or more longitudinal edges and / or along the surfaces of the rolling stock (1) adjoining the longitudinal edges to a further rolling stand (16) and

• subsequent rolling into a rolling stock (1) with a circular cross section in at least one closed caliber (6), in which the rolling forces act in a star shape on the rolling stock (1) from at least three directions and deform the rolling stock (1).

2. Precision rolling method according to claim 1, characterized in that the rolling stock (1) in two successively arranged duo rolling stands (15 ', 15) rolled into a rolling stock (1) with a tetragonal cross section and between these two duo rolling stands

(15 ", 15) is performed.

3. Profile rolling device for the production of rolling stock with a circular cross-section, characterized by:

At least one duo mill stand (15, 15 ') with an open, polygonal, in particular tetragonal, roll caliber (5),

• a rolling stock guide (17) adjoining the duo rolling stand (15) in the rolling direction (c) with the rolling stock (1) emerging from the duo rolling stand (15) on one or more longitudinal edges and / or on the longitudinal edges of the rolling stock Areas of the rolling stock guiding devices (64) and

• at least one further roll stand (16) with a closed circular caliber (6) with at least three rollers (7 to 10) arranged in a star shape.

4. Profile rolling device according to claim 3, characterized in that two duo rolling stands (15 ', 15) are provided with a tetragonal roll caliber with an intermediate guide.

5. Profile rolling device according to claim 3 or 4, characterized in that the rollers (7 to 10) of the further roll stand (16) via conical surfaces (7a to 10b) are supported against one another, the rollers (7 to 10) being pressed against one another with a setting force which exceeds the rolling force by a pretensioning force.

6. Profile rolling device according to one or more of claims 3 to 5, characterized in that the closed caliber (6) has a cross-sectional area which is 5 to 20% smaller than that of the open caliber (5) of the duo roll stand (15) .

7. Profile rolling device according to one or more of claims 3 to 6, characterized in that the further roll stand (16) has four rollers (7 to 10), in particular disc rollers, of which only two rollers lying opposite one another

(7, 8) can be driven by means of a motor, in particular with a common motor, and that each of the four rollers (7 to 10) has a conical surface (7a to 10b) on a conical surface of a further roller (7 to 10) abuts, each roller (7 to 10) abuts two adjacent rollers (7 to 10) and over the conical surfaces (7a to 10b) of the rollers (7 to 10) a closed power flow and a friction drive for the non-motor driven rollers (9, 10).

8. Profile rolling device according to claim 7, characterized in that the driven rollers (7, 8) of the further roll stand (16) have a larger diameter in the shaping surfaces (11, 12) than the rollers (9, not driven by their own drive) 10).

9. Profile rolling device according to claim 7 or 8, characterized in that the drivable by a motor rollers (7, 8) of the further roll stand (16) in the direction of their shaft against the two further rollers (9, 10) are displaceable.

10. Profile rolling device according to one or more of claims 7 to 9, characterized in that the further rolling stand (16) has two stand stands (62, 63) which are biased against each other via tie rods (58, 59) and threaded nuts (60, 61) .

11. Profile rolling device according to claim 10, characterized in that the threaded nuts (60, 61) are designed as hydraulic nuts.

12. Profile rolling device according to one or more of claims 3 to 1 1, characterized in that the duo roll stand (15) and / or the further roll stand (16) is arranged on a respective stand changing carriage (19), which along rails into one Working position can be pushed and fixed there and can be pushed from this position into a rest position.

13. Profile rolling device according to one or more of claims 3 to 12, characterized in that the shaping surfaces (11 to 14) of the closed caliber (6) forming rollers (7 to 10) have a draft at the contiguous circular edges (Fig. ld).

14. Profile rolling device according to one or more of claims 3 to 13, characterized in that the guide devices (64) are formed by profile rollers.