Processing method and plant for welding metal strips

Abstract

A processing plant for metal strips (1) has a welding machine, a strip store downstream of the welding machine and a processing device downstream of the strip store. The metal strips are welded to form a continuous strip with the welding machine, which is stored in the strip store and output from there to the processing device. The metal strips are connected via diagonally extending weld seams. To join the weld seams, first the strip head (2) and the strip foot (3) of the metal strips are twisted and the two strips are connected by forming the weld seam. The weld seam extends only transversely to the transport direction (x) during the welding process. Finally, the strip head and the strip foot of the metal strips are twisted back again. As a result, the weld seam now extends diagonally to the transport direction (x).

Claims

1. A processing method for processing metal strips in a processing plant, the processing plant including an accumulator, a welding machine upstream of the accumulator, and a processing device downstream of the accumulator, the method comprising: feeding a first metal strip to the welding machine and toward the strip accumulator in a transport direction (x), the first metal strip having a strip head with a leading edge, a strip tail with a trailing edge, and a fillet piece between the strip head and the strip tail thereof, feeding a second metal strip to the welding machine and toward the strip accumulator in the transport direction (x) while at least the strip tail of the first metal strip is in the welding machine, the first metal strip having a strip head with a leading edge, a strip tail with a trailing edge, and a fillet piece between the strip head and the strip tail thereof, inside the welding machine, rotating the first metal strip and the second metal strip so that the first and the second metal strip are oriented in a direction that is at an oblique angle () to the transport direction (x), inside the welding machine, cutting through the strip head of the rotated second metal strip and the strip tail of the rotated first metal strip along a direction that is perpendicular to the transport direction (x), thereby creating a new leading edge for the strip head of the second metal strip and a new trailing edge of the strip tail of the first metal strip, inside the welding machine, welding the new leading edge of the strip head of the second metal strip to the new trailing edge of the strip tail of the first metal strip to obtain a weld seam, wherein, when viewed transversely to the transport direction (x), the weld seam extends from a first lateral edge that runs along the transport direction (x) of one of the two metal strips to a second lateral edge thereof, storing the welded first and second metal strips in the strip accumulator, and feeding the welded first and second metal strips continuously or intermittently from the strip accumulator to the processing device, wherein first the strip heads, then the fillet pieces, and only then the strip tails of the first and second welded metal strips are fed to the processing device.

2. The processing method as claimed in claim 1, wherein the first metal strip and the second metal strip are rotated by forming loops in the first metal strip and the second metal strip.

3. The processing method as claimed in claim 1, wherein the processing device is designed as a rolling mill having at least one roll stand, in that the metal strips are rolled with a respective compressed length in the roll stands of the processing device, and in that a longitudinal extent which the weld seam has, when viewed in the transport direction (x), before rolling in the respective roll stand, is greater than the respective compressed length.

4. The processing method as claimed in claim 1, wherein the oblique angle () is approximately 5 to 10 from 90.

5. The processing method as claimed in claim 1, wherein the processing device is designed as a rolling mill having at least one roll stand.

6. The processing method as claimed in claim 1, wherein the oblique angle () is 6 to 8 from 90.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-described properties, features and advantages of this invention and the manner in which these are achieved will become more clearly and distinctly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in greater detail in combination with the drawings. Here, in schematic illustration:

(2) FIG. 1 shows a metal strip,

(3) FIGS. 2 to 5 show a processing plant for metal strips in various, chronologically successive operating states,

(4) FIG. 6 shows a plan view of a weld seam, and

(5) FIG. 7 shows a plan view of two metal strips before welding.

DESCRIPTION OF THE EMBODIMENTS

(6) According to FIG. 1, metal strips 1 are elongate flat rolled products. The metal strips 1 are conveyed in a transport direction xsee also the further FIGURES below. The leading region of the respective metal strip 1 forms what is referred to as the strip head 2, while the trailing region forms what is referred to as the strip tail 3. In between, there is a central region of the respective metal strip 1, referred to as the fillet piece 4. The exact boundaries between the strip head 2 and the fillet piece 4 and between the fillet piece 4 and the strip tail 3indicated by dashed lines in FIG. 1are of secondary importance. The respective strip head 2 ends at a respective leading edge 5, and the respective strip tail 3 ends at a respective trailing edge 6. Extending between the respective leading edge 5 and the respective trailing edge 6 are respective lateral edges 7 of the metal strip 1. The lateral edges 7 run parallel to the transport direction x.

(7) In the further FIGURES, the metal strips 1 have a small letter a, b, etc. added as a suffix to enable them to be distinguished from one another, if required, in the course of the description of the present invention. The same applies to the various parts and sections of the metal strips 1, for example the strip heads 2 and the strip tails 3.

(8) According to FIG. 2, a processing plant for the metal strips 1 has a strip accumulator 8. According to the illustration in FIG. 2, for example, the strip accumulator 8 can have a number of upper rollers 9 and lower rollers 10, the metal strips 1 in the strip accumulator 8 being guided alternately over one of the upper rollers 9 and one of the lower rollers 10. The upper rollers 9 can, for example, be arranged in a fixed manner, while the lower rollers 10 can be lowered with respect to the upper rollers 9. The quantity of metal strip 1 which is stored in the strip accumulator 2 varies, depending on the extent to which the lower rollers 10 are lowered.

(9) The processing plant furthermore has a processing device 11. According to the illustration in FIG. 1, the processing device 11 can, for example, be designed as a multi-stand rolling train. In this case, as a rule, cold rolling takes place in the rolling train. However, other embodiments of the processing device 11 are also possible, whether in addition to or as an alternative to a rolling train. For example, the processing device 11 can be a pickling unit or can comprise a pickling unit in addition to the rolling train. In the latter case, the pickling unit is arranged upstream of the rolling train. Regardless of its specific configuration, however, the processing device 11 is arranged downstream of the strip accumulator 8.

(10) Finally, the processing plant has a welding machine 12. The welding machine 12 is arranged upstream of the strip accumulator 8.

(11) The processing plant is operated as follows:

(12) At a certain point in time, a certain quantity of metal strip 1 is stored in the strip accumulator 8. For example, in the state according to FIG. 2, with the exception of its strip tail 3c, metal strip 1c, and the strip tail 3b and a majority of the fillet piece 4b of metal strip 1b are stored. The strip head 2b of metal strip 1b and metal strip 1a have already left the strip accumulator 8. Specifically, the strip head 2b of metal strip 1b is still being transported to the processing device 11, while metal strip 1a is already in the processing device 11 or may already have left the processing device 11.

(13) The strip tail 3c of metal strip 1c is still in the welding machine 12. The strip head 2d of metal strip 1d is to be applied to the strip tail 3c of metal strip 1c. For this purpose, the strip head 2b of metal strip 1d is fed to the welding machine 12. For this purpose, metal strip 1d is generally uncoiled to a corresponding extent from a coiler 13. Specifically, uncoiling takes place to such an extent that the strip head 2d of metal strip 1d is moved within the welding machine 12 into the immediate vicinity of the strip tail 2c of metal strip 1c. According to the illustration in FIG. 3, the leading edge 5d of metal strip 1d thus adjoins the trailing edge 6c of metal strip 1c with an extremely small clearance (at most a few millimeters).

(14) In this state, the leading edge 5d of metal strip 1d is welded to the trailing edge 6c of metal strip 1c by means of the welding machine 12. Between these two edges 5d, 6c, therefore, a weld seam 14 is formed. As a result of the welding, metal strip 1d has become a constituent part of a continuous strip which previously comprised only metal strips 1a, 1b and 1c. FIG. 4 shows this state. After welding, the strip tail 3c of metal strip 1c and the strip head 2d and the fillet piece 4d of metal strip 1d are fed to the strip accumulator 8 in the transport direction x. The feeding of metal strip 1d takes place to such an extent that the strip tail 3d still remains in the welding machine 12. FIG. 5 shows the corresponding state.

(15) As far as the feeding of the metal strips 1 to the strip accumulator 8 is concerned, a complete cycle is completed by the procedure explained above. This cycle is repeated again and again, and therefore a new metal strip 1 is repeatedly welded to the previous metal strip 1 and fed to the strip accumulator 8. As a result, the metal strips 1 are thus fed intermittently and sequentially in succession to the strip accumulator 8. Furthermore, the transport direction x for the metal strips 1 isas an entirely natural resultuniform, and each metal strip 1 runs first with its strip head 2, then with its fillet piece 4 and finally with its strip tail 3 into the strip accumulator 8.

(16) The metal strips 1 (or the corresponding sections of the continuous strip) stored in the strip accumulator 8 can be fed to the processing device 11 as required. It is possible in individual cases for feeding to take place intermittently. As a rule, however, it takes place continuously. This too can be seen from FIGS. 2 to 5.

(17) In particular, the weld seams 14 between metal strips 1a and 1b and metal strips 1b and 1c in the state according to FIG. 2 are located at specific points and, furthermore, the lower rollers 10 are located at a specific height level, which in turn corresponds to the degree of filling of the strip accumulator 8. A period of time elapses before the strip head 2d of metal strip 1d is brought up to the strip tail 3c of metal strip 1cillustrated in FIG. 3. During this period of time too, as a rule, the continuous strip is conveyed out of the strip accumulator 8 and, in association therewith, the continuous strip is fed to the processing device 11. In comparison with the state illustrated in FIG. 2, however, the location of the strip tail 3c has not changed. As a result of the continuous strip being conveyed out of the strip accumulator 8, the degree of filling of the strip accumulator 8 has thus been reduced. Correspondingly, the lower rollers 10 are raised as compared with the state in FIG. 2. Furthermore, the locations at which the weld seams 14 between metal strips 1a and 1b and metal strips 1b and 1c are located have changed.

(18) Similarly, a period of time is also required to form the weld seam 14 between metal strips 1c and 1dillustrated in FIG. 4. During this period of time too, the continuous strip is conveyed out of the strip accumulator 8 and, in association therewith, the continuous strip is fed to the processing device 11. In comparison with the state illustrated in FIG. 3, the location of the strip tail 3c has, as before, not changed. As a result of the continuous strip being conveyed out of the strip accumulator 8, however, the degree of filling of the strip accumulator 8 has been reduced even further. Correspondingly, the lower rollers 10 are raised even further as compared with the state in FIG. 2. Moreover, the locations at which the weld seams 14 between metal strips 1a and 1b and metal strips 1b and 1c are located have once again changed as compared with the state in FIG. 3.

(19) A certain period of time is also required for the feeding of the strip tail 3c of metal strip 1c and the strip head 2d and the fillet piece 4d of metal strip 1d to the strip accumulator 8. The locations at which the weld seams 14 between metal strips 1a and 1b and metal strips 1b and 1c are located have thus changed again. However, the feeding of the strip tail 3c of metal strip 1c as well as of the strip head 2d and of the fillet piece 4d of metal strip 1d to the strip accumulator 8 takes place at a higher speed than the discharge of the continuous strip from the strip accumulator 8. Thus, owing to the feeding of the strip tail 3c of metal strip 1c and the strip head 2d and the fillet piece 4d of metal strip 1d to the strip accumulator 8, the degree of filling of the strip accumulator 8 is increased in spite of the simultaneous discharge of the continuous strip from the strip accumulator 8. Correspondingly, the lower rollers 10 are lowered in comparison with the state in FIG. 4, generally to the same or at least a similar level as in FIG. 2.

(20) Analogously to the feeding of the metal strips 1 to the strip accumulator 8as an entirely natural resulteach metal strip 1 is, as can be seen, fed first with its strip head 2, then with its fillet piece 4 and finally with its strip tail 3 to the processing device 11.

(21) The configuration of the weld seam 14 between metal strips 1c and 1d is explained below in conjunction with FIG. 6. However, the corresponding statements also apply 1:1 to the weld seams 14 between other metal strips 1.

(22) As a rule, the metal strips 1c, 1d are placed against one another centrally as shown in FIG. 6. In this case, the weld seam 14 extends from the lateral edge 7c, 7d of one of the two metal strips 1c, 1d to the other lateral edge 7c, 7d of the same metal strip 1c, 1d, irrespective of whether the metal strips 1c, 1d have the same strip width bc, bd or strip widths bc, bd which are different from one another. This case can also occur in the event of eccentric connection of the metal strips 1c, 1d. In the case of eccentric connection of the metal strips 1c, 1d, however, it is possible for the weld seam 14 to extend from the lateral edge 7c, 7d of one of the two metal strips 1c, 1d to a lateral edge 7d, 7c of the other metal strip 1d, 1c. Irrespective of whether one or the other case is implemented, however, an angle which the weld seam 14 forms with the transport direction x differs, at least in some section or sections, from 90. The welding machine 12 is designed in such a way that it can form this weld seam 14, and is also operated in this way.

(23) The extent to which the angle differs from 90 can be determined as required. For example, the deviation from 90 can be about 5 to 10, in particular between 6 and 8.

(24) The welding operation as such and also the preparation of the leading edge 5 of one metal strip 1 and of the trailing edge 6 of the other metal strip 1 need not be explained in greater detail.

(25) Specifically for a diagonal profile of the weld seam 14, it is furthermore possible, by clamping corresponding regions of the strip head 2 of one metal strip 1 and of the strip tail 3 of the other metal strip 1 and forming loops, for the metal strips 1 to run obliquely at the angle in the welding machine 12. FIG. 7 shows this state of the metal strips 1. In this state, the leading edge 5 of one metal strip 1 and the trailing edge 6 of the other metal strip 1 can then be prepared in a completely conventional manner. The cutting-offindicated in FIG. 7 by dashed linescan likewise be carried out in a completely conventional manner orthogonally to the transport direction x. The welding can also take place in a manner which is likewise completely conventional and orthogonal to the transport direction x. Owing to the fact that the strip head 2 of one metal strip 1 and the strip tail 3 of the other metal strip 1 run obliquely at the angle during the welding operation but align themselves again in the transport direction x after welding (see FIG. 6), the weld seam 14 runs at the angle after welding.

(26) The present invention has many advantages. In particular, due to the profile of the weld seams 14, the processing device 11 does not act on the weld seams 14 over the entire width of the weld seams 14 at a particular time, but only over a partial region in each case. As a result, only a partial region of the respective weld seam 14 is subjected to processing at any one point in time. Particularly in stretcher levelers and rolling mills, it is no longer necessary to vary the processing process for the weld seams 14. Off-gage lengths which have to be segregated out as scrap can thereby be reduced. The yield can thus be increased. The risk of strip tearing can be reduced to almost zero. A further positive effect is that maintenance intervals of the welding machine 12 can be increased and the maintenance of the welding machine 12 is also simplified. Downtimes of the processing plant can thereby be reduced, which likewise increases productivity. Furthermore, it is also possible to retrofit conventional welding machines 12 correspondingly in such a way that they can produce a diagonal profile of the weld seam 14.

(27) Although the invention has been illustrated and described more specifically in detail by means of the preferred exemplary embodiment, the invention is not restricted by the examples disclosed, and other variants can be derived therefrom by a person skilled in the art without exceeding the scope of protection of the invention.

LIST OF REFERENCE SIGNS

(28) 1 metal strips 2 strip heads 3 strip tails 4 fillet pieces 5 leading edges 6 trailing edges 7 lateral edges 8 strip accumulator 9 upper rollers 10 lower rollers 11 processing device 12 welding machine 13 uncoiler 14 weld seams b strip widths x transport direction angle