GB2168280A

GB2168280A - Roll sizing pass arrangement for rod-rolling and wire-rolling lines or blocks

Info

Publication number: GB2168280A
Application number: GB08530259A
Authority: GB
Inventors: Werner Demny
Original assignee: Kocks Technik GmbH and Co KG
Current assignee: Kocks Technik GmbH and Co KG
Priority date: 1984-12-12
Filing date: 1985-12-09
Publication date: 1986-06-18
Also published as: IT8522393A0; IT1200763B; GB8530259D0; DE3445219C2; FR2574320A1; JPS61242706A; DE3445219A1

Abstract

A roll sizing pass arrangement for continuously operating bar-rolling and wire-rolling lines or blocks, comprises a plurality of sizing passes each comprising three rolls (2). Working sizing passes (8) disposed at the entry end have sizing pass openings with substantially straight contour lines, and two dimensioning sizing passes (7) disposed at the delivery end directly beyond the last pass (8) have sizing pass openings with substantially circular contour lines. Furthermore, the last dimensioning sizing pass (7a) but one performs a minimum cross- sectional reduction of 8%, and the last dimensioning sizing pass (7b) performs a maximum cross-sectional reduction of 3.8%. <IMAGE>

Description

SPECIFICATION Roll Sizing Pass Arrangement for Rod-rolling and Wire-rolling Lines or Blocks The invention relates to a roll sizing pass arrangement comprising several sizing passes, each consisting of three rolls.

A roll sizing pass arrangement for continuously operating rod-rolling and wire-rolling lines or blocks is already known (German Patent Specification No.

10 73 990), in which a number of working sizing passes each formed by three rolls is disposed at the entry end, and a dimensioning sizing pass also comprising three rolls is provided as the last sizing pass at the delivery end. The working sizing passes are distinguished by the fact that they have sizing pass openings with straight contour lines.

Moreover, the working sizing passes achieve particularly large cross-sectional reductions of, for example, 15% to 28% per sizing pass. In contrast to this, dimensioning sizing passes each have a substantially circular sizing pass opening whose dimensions and cross-sectional configurations substantially correspond to those of the desired finished cross-section of the work-material.

Only one dimensioning sizing pass of this kind is provided in this known type of construction, since even the last sizing pass but one has a sizing pass opening with substantially straight contour lines, so that, like all the sizing passes disposed upstream thereof, it has to be regarded as a working sizing pass. The work-material emerging from the last working sizing pass and whose cross-sectional configuration is that of an irregular hexagon having three long sides and three short sides, enters the last dimensioning sizing pass, that is to say, the single dimensioning sizing pass, in such a way that the long, straight sides of the hexagon are located in the region of the gaps between the rolls of the dimensioning sizing pass.Since three-roll sizing passes have the advantageous characteristic that the work-material therein widens to a far lesser extent, that is to say, it is subjected to less deformation transversely of the longitudinal direction of the work-material, than in the case of sizing passes formed by two rolls, the work-material in the dimensioning sizing pass is not deformed to a sufficient extent in a direction towards the gaps between the rolls, so that a fiat is still perceptible as a remainder of the long straight sides of the hexagon on the three corresponding circumferential portions of the finished work-material. This phenomenon is promoted by the fact that a smaller cross-sectional reduction is effected in the dimensioning sizing pass in order to obtain close dimensional tolerances.Consequently, it has not been possible to produce a circular finished crosssection in this known roll sizing pass arrangement.

In order to improve the finished cross-section, a different roll sizing pass arrangement has been proposed (Journal "Iron and Steel Engineer", March 1966, Page 115) in which a transition sizing pass is used downstream of the last working sizing pass, the working surfaces of the three rolls of the transition sizing pass being slightly concave, so that the region of the three largest circumferential portions of the cross-section of the work-material have convex outer surfaces which are consequently preformed with regard to the round of the following dimensioning sizing pass. This transition sizing pass is frequently called an "oval sizing pass", although it is not oval in the normal sense of the word. Only in this known roll sizing pass arrangement, are two dimensioning sizing passes having substantially circular openings provided downstream of the transition sizing pass.This roll sizing pass arrangement is described in further detail in the Journal "Drahtwelt" 57 (1971), No. 9, paragraph 1 in the right-hand column on page 443. Accordingly, a cross-sectional reduction of 10% is effected in the "oval" transition sizing pass, and a cross-sectional reduction of 5% is effected in each of the two following dimensioning sizing passes having circular openings, that is to say, equal crosssectional reductions are performed in the two dimensioning sizing passes.

Twisting of the wire, that is to say, turning of the wire about its longitudinal axis downstream of the "oval" transition sizing pass and the first circular dimensioning sizing pass, could not be avoided with these sizing pass configurations and cross-sectional reductions. The flat locations occurring in the region of the gaps of the "oval" transition sizing pass turned by themselves in such a way that they were always to be found in the region of the gaps between the rolls in the first dimensioning sizing pass and also in the second and last dimensioning sizing passes, where they remained flat. Attempts to eliminate these flats by filling the sizing pass to a greater extent only led to rib-like protrusions caused by the work material entering the gaps between the rolls.Consequently, wire or bar material of true circular cross-section also could not be rolled with this known roll sizing pass arrangement.

It is known that, with sizing passes comprising two rolls, a circular finished cross-section can only be obtained in the last dimensioning sizing pass when a cross-sectional reduction of approximately 10% is performed therein. However, this crosssectional reduction, which is relatively large for a dimensioning sizing pass, can only be achieved when the sizing pass opening of the neighbouring, next to last sizing pass, is not circular. If the next to last sizing pass were circular, all the circumferential regions of the work-material in the last sizing pass, which is also circular, would have to be subjected to uniform rolling pressure radially inwardly. However, this is impossible in the region of the gaps between the rolls.Since the working surfaces of the rolls and the radial rolling pressure are absent in this region, the work-material enters the gaps between the rolls and rib-like protrusions are formed, so that workmaterial having a truly circular cross-section is not produced even when using two successive dimensioning sizing passes with circular sizing pass openings and large reductions in the last sizing pass irrespective of whether it is formed by two or three rolls. In the case of smaller reductions in the dimensioning sizing pass of, for example, 5%, the work-material cannot be guided satisfactorily or cannot be guided at all, in the oval transition sizing pass disposed upstream, so that the work-material turns about its longitudinal axis, that is to say, it twists, hence resulting in unserviceable crosssectional configurations.

A direct transition from a next to last sizing pass opening having straight contour lines to a last sizing pass opening having circular contour lines, as in German Patent Specification No. 10 73 990, is unsatisfactory for the reasons set forth initially. The use of two circular sizing pass openings in the two dimensioning sizing passes at the delivery end, corresponding to the Journal "Iron and Steel Engineer", March 1966, page 115, was also unsuccessful for the reasons given above.

Therefore, a third roll sizing pass arrangement was developed in which the last working sizing pass, the third from last sizing pass, actually produces a work-material cross-section in the form of a regular hexagon. The last sizing pass but one was in the form of an "oval" transition sizing pass with rolls having slightly concave working surfaces, so that work-material having a somewhattriangularcross- section with convex surfaces was produced. The following dimensioning sizing pass, that is to say, the last sizing pass opening, was circular. This roll sizing pass arrangement is illustrated in the Journal "Drahtweit" 57 (1971) No. 9, page 442, and is described in paragraph 2 in the right-hand column on page 443.In this roll sizing pass arrangement, three slightly curved circumferential portions, corresponding to the concave profiling of the working surfaces of the rolls, are formed on the work-material in the next to last "oval" sizing pass opening. The corresponding slightly convex circumferential portions of the work-material are located in the following circular finishing sizing pass in the region of the gaps between the rolls where they are again largely retained owing to the advantageously small amount of broadening in the three-roll sizing pass. Consequently, the finished cross-section of the work-material is not circular even downstream ofthis roll sizing pass arrangement, even if it is better than in the case of the known roll sizing pass arrangements described previously.

The invention relates to a roll sizing pass arrangement for continuously operating rod-rolling and wire-rolling lines or blocks, comprising a plurality of sizing passes each comprising three rolls, in which arrangement working sizing passes disposed at the entry end have sizing pass openings with substantially straight contour lines, and dimensioning sizing passes disposed at the delivery end have sizing pass openings with substantially circular contour lines. The reason why the contour lines are not completely straight or completely circular resides in the fact that the sizing pass openings are widened or relieved in the regions of the gaps between the rolls or in the edge regions of the working surfaces of the rolls in order to avoid line-like depressions in the work-material which would otherwise occur in these regions.The aforementioned contour lines of the sizing pass openings are otherwise actually straight or circular.

An object of the invention is to provide a roll sizing pass arrangement of the aforementioned type having three rolls per sizing pass and with which it is possible to roll work-material having a substantially truly circular cross-section.

In accordance with the invention, a roll sizing pass arrangementfora rod-rolling orwire-rolling line or block comprises a plurality ofthree-rolI sizing passes, the last two of which are dimensioning sizing passes each having a sizing pass opening with a substantially circular contour line and the remainder of which are working sizing passes, at least the last of which, immediately upstream of the first of the two dimensioning sizing pass openings, has a sizing pass opening with substantially straight contour lines, the first dimensioning sizing pass being designed to achieve a reduction of at least 8% and the second dimensioning sizing pass downstream thereof being designed to achieve a reduction of at most 3.8%.

The "oval" transition sizing paths with its slightly curved contour lines has been obviated in this roll sizing pass arrangement, and only working sizing passes whose openings have straight or substantially straight contour lines, and dimensioning sizing passes whose openings have circular or substantially circular contour lines, are used. Consequently, in the roll sizing pass arrangement in accordance with the invention, as in the case of the known sizing pass arrangement first described, work-material having straight contour lines enters a circular opening of a dimensioning sizing pass, the difference between the present invention and this known sizing pass arrangement residing in the fact that a second, likewise circular sizing pass opening follows this first circular sizing pass opening, this feature not being provided in the known, aforementioned sizing pass arrangement.

Although the known roll sizing pass arrangement described above in the second place also has the second circular sizing pass opening, the two circular sizing pass openings each operate with the same cross-sectional reduction of 5%, and an "oval" transition sizing pass having a cross-sectional reduction of approximately 10% is provided upstream of the dimensioning sizing passes and downstream of the working sizing passes.

The roll sizing pass arrangement in accordance with the invention, which distinctly differs from the known types of construction in this way, is able to produce a circular work-material cross-section due to the fact that the straight circumferential portions of the work-material produced in the last working sizing pass are provided with a circular configuration firstly by the cross-sectional reduction of more than 8% in the first dimensioning sizing pass, and then by direct rolling in the bottom of the second dimensioning sizing pass, that is to say, by the middle portions of the working surfaces of the rolls. Hence, all the straight circumferential portions of the work-material downstream of the last working sizing pass are rolled at least once by a sizing pass bottom of one of the rolls of the dimensioning sizing passes and are thus provided with the desired circular configuration. In contrast to the known roll sizing pass arrangement described in the second place, this is possible in the arrangement in accordance with the invention due to the fact that, owing to the guidance rendered possible by the omission of the "oval" transition sizing pass, the work-material no longer twists upon entering the circular opening of the first dimensioning sizing pass, that is to say, it no longer turns about its longitudinal axis. Even in the second dimensioning sizing pass, the critical circumferential portions can no longer twist to escape being rolled by a respective sizing pass bottom, but are satisfactorily rolled and are provided with the desired curvature.

The latter is achieved primarily due to the fact that the cross-sectional reduction in the last dimensioning sizing pass is less than 3.8%, and consequently the twisting forces occurring are smaller than the forces offered by the work-material to resist turning. Consequently, there is also no need for guidance of the work-material between the last dimensioning sizing pass and the next to last dimensioning sizing pass, which guidance may, in accordance with the invention, be omitted. Those guidance forces which emanate from the sizing passes located at the entry end upstream of the next to last dimensioning sizing pass are adequate. The risk of twisting upon entering the first dimensioning sizing pass is only very slight owing to the fact that the cross-section of the work-material has straight surfaces and can be guided satisfactorily.The tendency to twist is also very slight at this location, since the following first dimensioning sizing pass has a substantially circular opening, and for this reason the guide disposed upstream thereof is only stressed to a slight extent. The use of two dimensioning sizing passes incidentally results in substantially closer tolerances of the work-material.

It is advantageous if at least the rolls of the last working sizing pass are adjustable in a radial direction. It is thereby possible to provide the work-material, emerging from the last working sizing pass, with various cross-sectional configurations and dimensions, and particularly to vary the K value. The K value is the ratio of the radius of the inscribed circle of the sides of the work-material not rolled in that pass to the radius of the inscribed circle of the sides of the work-material which are rolled by the rolls of that pass. This K value can vary to a considerable extent. It generally lies between 0.7 and 1.4.In this manner, it is possible, with only one row of working sizing passes, to roll continuously from only one first pass entry cross-sectional area all finished dimensions lying within the limits determined by the smallest possible and largest possible total reduction of the rolling line or rolling block. It will be appreciated that fresh sizing pass openings have to be repeatedly incorporated in the two dimensioning sizing passes as soon as a different finished cross-section is desired. It is advisable also to equip the dimensioning sizing passes with radially adjustable rolls. The K value can also be varied to a certain extent just by varying the tension exerted on the work-material in a longitudinal direction between the individual sizing passes in order to obtain a specific circular finished cross-section, namely when the K values are greater than 1.

However, if the K values are smaller than 1, it is advantageous, in accordance with a further feature of the invention, to dispose the rolls of the first dimensioning sizing pass in the same angular position as the rolls of the last working sizing pass disposed upstream of the first dimensioning sizing pass. In this arrangement of the rolls, the substantially hexagonal cross-section of the workmaterial is deformed in the first dimensioning sizing pass, having a circular opening, in the same direction as in the last working sizing pass in which it was produced. This is the only way in which it is possible to roll a circular cross-section with a K value smaller than 1 at the exit from the last working sizing pass.The work-material would otherwise immediately enter the gaps between the rolls, since the cross-sectional regions having the largest deformation are located directly upstream of the gaps between the rolls of the first dimensioning sizing pass. If it is desired to avoid this, the diameter of the first dimensioning sizing pass would have to be sufficiently large to substantially reduce the amount of deformation in the region of the gaps between the rolls. However, the result of a diameter of this size would be that the free circumferential portions of the incoming cross-section of the workmaterial would not reach the bottom of the respective sizing pass and would consequently remain straight.

The layout for a small K value such as this in the last working sizing pass has the advantage that the same circular finished cross-section can be rolled with differing amounts of reduction in the last working sizing pass and in the first dimensioning sizing pass without having to vary the tension exerted on the work-material in a longitudinal direction. The latter would otherwise be unavoidable, and considerable changes in tension would be necessary. Differing amounts of reduction in the last working sizing pass and hence also in the first dimensioning sizing pass when always rolling the same finished cross-section have the advantage that the wear on the highly stressed first dimensioning sizing pass can be controlled.The greatest amount of wear in a dimensioning sizing pass of this kind occurs at the locations where the corners of the incoming, substantially hexagonal cross-section encounter the working surfaces of the rolls. If, during a production run the amount of reduction in the last working sizing pass is changed, and hence the K value is changed, the amount of reduction in the first dimensioning sizing pass is also changed, particularly the position of the corners of the cross-section of the work-material, so that these corners encounter other regions of the working surfaces of the rolls, and consequently the regions of the working surfaces of the rolls which are subjected to the greatest stress are shifted. This shift results in a longer service life of the rolls of the first dimensioning sizing pass and hence lower expenditure on trolls.This is particularly advisable and advantageous in the case of a long production run in which a large quantity of work-material is rolled to one finished dimension, since the wear of the dimensioning rolls can be spread over the surfaces of these rolls, thereby avoiding any interruption of the production run to replace or re-grind the dimensioning rolls.

In a further development of the invention, the last working sizing pass on the one hand and the two dimensioning sizing passes on the other hand are driven at speeds which are independent of one another and of the otherworking sizing passes. It is thereby possible to vary the amounts of reduction in the last working sizing pass and in the first dimensioning sizing pass. Forthis purpose, the rolls of the last working sizing pass on the one hand, and the rolls of the two dimensioning sizing passes on the other hand, may be driven by separate motors. It has proved to be advantageous if the rolls of the two dimensioning sizing passes are commonly driven, possibly byway of an overrunning clutch upstream of the last dimensioning sizing pass.As a result of the overrunning clutch, the rotational speed of the second and last dimensioning sizing passes may be greater than the fixedly predetermined step-up to the first dimensioning sizing pass. An additional step-change gear as used in some known types of construction is not required when all finished dimensions are rolled from the same first pass entry cross-sectional area.

The invention is further described, by way of example, with reference to the drawings, in which: Fig. lisa sectional diagram of the last three sizing pass openings at the delivery end of a known roll sizing pass arrangement; Fig. 2 is a similar diagram of the lastthree sizing pass openings at the delivery end of a roll sizing pass arrangement in accordance with one embodiment of the invention; Fig. 3 is a similar diagram of the last three sizing pass openings at the delivery end of a roll sizing pass arrangement in accordance with another embodiment of the invention; Fig. 4 is a schematic plan of a rolling block together with a drive of known construction; and Fig. 5 is a similar plan of a rolling block together with a drive in accordance with the invention.

Fig. 1 shows three working surfaces 1 of three rolls 2 which form the last working sizing pass 8 and which are disposed in a conventional stellate manner, only one peripheral edge region of the rolls being shown. Gaps 3 are provided between the rolls 2 in order to avoid damage to the rolls 2. The greater portion of an opening 4, formed in this manner, of this last working sizing pass 8 is filled with workmaterial 5. The dimension "a" is the radius of an inscribed circle of the non-engaged sides, and the dimension "b" is the radius of an inscribed circle of those sides of the work-material 5 which are in contact with the working surfaces 1 of the rolls 2.

These two inscribed circles are not drawn. The ratio a/b is the so-called Kvalue. In Fig. 1,the Kvalue is greater than 1.

The rolls 2 of an adjacent transition sizing pass 4a at the delivery end, have concave working surfaces 6, so that ccnvex circumferential portions are imparted to the work-material Sat these locations.

The work-material 5 runs from this transition sizing pass 4a, generally celled "oval", into a sizing pass 4b which has a circular opening and which is in turn formed by three rolls 2 and which, in this known sizing pass arrangement constitutes the first and last dimensioning sizing pass. The sizing pass opening is slightly widened in the region of the gaps 3 between the rolls, that is to say, it differs from the otherwise circular configuration to increase the size of the sizing pass opening 4b.

The embodiment of roll sizing pass arrangement for a continuously operating rod-rolling or wirerolling line or block, in accordance with the invention and as shown in Fig. 2, differs from the known roll sizing pass arrangement of Fig. 1 in that the "oval" transition sizing pass 4a is replaced by a first dimensioning sizing pass 7a having a circular cross-sectional configuration. The first dimensioning sizing pass 7a is also widened or relieved in the regions of the gaps 3 between the rolls in the same manner as in the known dimensioning sizing pass 4b of Fig. 1. This widening is shown by the radius R which is slightly larger than the radius D of this sizing pass opening. The ratio 2R/D should be less than 1.15.Since the crosssectional reduction in this first dimensioning sizing pass 7a is, in accordance with the invention, larger than that in the last one and only dimensioning sizing pass 4b of the known roll sizing pass arrangement, the widenings in the region of the roll gaps 3 in the first dimensioning sizing pass 7a of Fig.

2 must also be somewhat larger in order to prevent the work-material 5 from entering the roll gaps 3.

There is scarcely any perceptible widening in the region of the gaps 3 between the rolls of the second and last dimensioning sizing pass 7b of Fig. 2, since, in accordance with the invention, the amount of reduction in this dimensioning sizing pass 7b is significantly smaller than that in the first dimensioning sizing pass 7a disposed upstream thereof.

In the embodiment of the invention shown in Fig.

3, the two rolls 2 of the two dimensioning sizing passes 7a and 7b are angularly offset relative to those of Fig. 2. The special feature in this is that the rolls 2 of the first dimensioning sizing pass 7a of Fig.

3 thus assume the same positions as the rolls 2 of the last working sizing pass 8. Fig. 3 also clearly shows that the dimension "a" is smaller than the dimension "b", and that consequently a K value of less than 1 is obtained. In the case of a K value as small as this, it is necessary to dispose the rolls 2 of the following first dimensioning sizing pass 7a in the same manner as the rolls 2 of the last working sizing pass 8. In the present case, this means that the two rolls 2 are disposed with a horizontal axis below the longitudinal central axis of the work-material 5. Only the second dimensioning sizing pass 7b again has the conventional staggered arrangement of its rolls 2 relative to its adjacent dimensioning sizing pass 7a disposed upstream thereof.

Fig. 4 shows that, in the known type of construction illustrated therein, and in a roll sizing pass arrangement of Fig. 1, only the "oval" transition sizing pass 4a and the single dimensioning sizing pass 4b each have a separate drive motor 10, whereas all the working sizing passes 8 are driven by a common motor 11 by way of a transmission 12 and a distribution gear 13.

In contrast to this, Fig. 5 shows a rolling block having the roll sizing pass arrangement in accordance with the invention and shown in Fig. 2 or Fig. 3. In this instance, the working sizing passes 8 disposed at the entry end are also driven by a common motor 11, with the exception of the last working sizing pass 8 which is illustrated in Figs. 2 and 3. The latter working sizing pass is driven by a separate motor 15. Furthermore, in the rolling block of Fig. 5, the two dimensioning sizing passes 7a and 7b disposed at the delivery end are commonly driven by a motor 16, an overrunning clutch 17 additionally being provided in the drive shaft for the second and last dimensioning sizing pass 7b in order to prevent the work-material 5 between the two dimensioning sizing passes 7a and 7b from being subjected to too great a stress or compression in a longitudinal direction according to the prescribed gear ratio.

Claims

1. A roll sizing pass arrangement for a rod-rolling or wire-rolling line or block comprises a plurality of three-roll sizing passes, the last two of which are dimensioning sizing passes each having a sizing pass opening with a substantially circular contour line and the remainder of which are working sizing passes, at least the last of which, immediately upstream of the first of the two dimensioning sizing pass openings, has a sizing pass opening with substantially straight contour lines, the first dimensioning sizing pass being designed to achieve a reduction of at least 8% and the second dimensioning sizing pass downstream thereof being designed to achieve a reduction of at most 3.8%.

2. A sizing pass arrangement as claimed in claim 1, in which the rolls of at least said last working sizing pass are adjustable in a radial direction with respect to the pass line.

3. A sizing pass arrangement as claimed in claim 1 or 2, in which the rolls of said first dimensioning sizing pass are disposed in the same angular positions as the rolls of said last working sizing pass.

4. A sizing pass arrangement as claimed in claim 1, 2 or 3, in which said last working sizing pass on the one hand and said two dimensioning sizing passes on the other hand are driven at rotational speeds which are independent of one another and of the other working sizing passes.

5. A sizing pass arrangement as claimed in claim 4, in which the rolls of said two dimensioning sizing passes are commonly driven.

6. A sizing pass arrangement as claimed in claim 5, in which the rolls of one of said two dimensioning sizing passes are driven via an overrunning clutch.

7. A roll sizing pass arrangement for a rod-rolling or wire-rolling line or block, constructed and adapted to operate substantially as herein described with reference to and as illustrated in Figs. 2,3 and 5 of the accompanying drawings.