|
(11) | EP 2 644 291 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
||||||||||||||||||||
| (54) | Entry section of a pickling line, of a continuous tandem cold mill (tcm) or of a pickling line coupled to tandem cold mill (pl/tcm) installation |
| (57) The present invention relates to a continuous industrial equipment having an entry
section comprising two uncoiling devices (1a, 1b) for uncoiling and feeding out strip
materials to be processed, a cutting device (2a, 2b) and a transfer table (3a, 3b)
for each strip, and a joining device (4), so that the transfer tables (3a, 3b) deliver
said strips to the joining device (4) where a coil tail strip and a coil head strip
are joined, at least a looping table (5) for strip centering and a welder (6) where
said coil tail strip and said coil head strip are butt welded, characterized in that
each of the transfer tables (3a, 3b) is also a looping table (5).
|
Field of the invention
[0001] The present invention relates to the field of continuous processes in the steel industry, leading to productivity and yield improvements as well as cost savings. These continuous processes are, for example, those carried out on pickling lines, possibly linked with cold rolling mills, or carried out on continuous rolling mills.
Background art
[0002] A technical problem known in the above-mentioned lines is that the entry section, where two following strips are welded together, is one of the main bottlenecks thereof. The time performance of the line entry is therefore critical to achieve the yearly production. This is all the more true when the coils deliver short lengths of strip.
[0003] The welding process needs creation of a loop in front of the welder. Existing solutions as the preloading table at Continuous Annealing Lines (CAL) or Continuous Galvanizing Lines (CGL) are not applicable for the processing of hot rolled strips. According to the high thickness and heavy weight of the loop, these hot rolled strips require a different entry design to allow safe loop creation and centering.
[0005] The entry time cycle represents the time during which the tail end of a coil and the head end of the next coil are being operated at slower speed than the pickling or rolling process one.
[0006] The entry cycle usually comprises the following steps:
- slowdown from process speed to threading speed;
- transfer of the first coil tail end from the first pay-off reel 1a to the first dividing shear 2a;
- cut at the first shear 2a;
- transfer of the first coil tail end to the common pinch roll 4 thanks to the first transfer table 3a;
- transfer of the first coil tail end from the common pinch roll 4 to the welder 6.
[0007] In parallel of these first steps, the following steps are performed so that the tail end of the first coil and the head end of the second coil can be butt welded without wasting time:
- transfer of the second coil (next coil) head end from the second pay-off reel 1b to the second dividing shear 2b;
- cut at the second shear 2b;
- transfer of the coil head end to the common pinch roll 4 thanks to the second transfer table 3b ;
- transfer of the second coil head end from the common pinch roll 4 to the welder 6 and loop creation at the looping table 5, this looping being necessary for coil centering at the welder;
- welding of the two coil ends together;
- re-acceleration to maximum entry speed.
[0008] During those operations, the intermediate pickling or rolling process section is still running at nominal speed thanks to the storage capacity of the looper.
[0009] Therefore, if the entry cycle time is reduced, then it allows to run faster in the pickling section for a same looper capacity.
Aims of the invention
[0010] The present invention aims at decreasing the time for entry cycle in steel industry continuous lines, thus reducing the production time of the above-mentioned lines.
[0012] Still a further goal is to eliminate or reduce the transfer time from the common pinch roll to the welder.
[0013] Still a further goal is to allow a better loop creation and a better centering for heavy strip gages.
Summary of the invention
[0014] A first object of the present invention relates to a continuous industrial equipment having an entry section comprising two devices for uncoiling and feeding out strip materials to be processed, a cutting device and a transfer table for each strip, and a joining device, so that the transfer tables deliver said strips to the joining device where a coil tail strip and a coil head strip are joined, at least a looping table for strip centering and a welder where said coil tail strip and said coil head strip are butt welded, characterized in that each of the transfer tables is also a looping table (claim 1).
[0015] According to example embodiments of the invention, possibly preferred embodiments, the continuous industrial equipment having an entry section is further limited according to one or a suitable combination of the following characteristics (claims 1 to 10):
- the equipment is provided so as the joined strips at the joining device are directly fed to the welder, without further looping;
- the transfer tables consisting in an upper table defining an upper entry level being superimposed on a lower table defining a lower entry level, the equipment is provided with means for retracting first and then lifting the upper table;
- each uncoiling devices comprises a pay-off reel;
- each cutting device comprises a shear;
- the joining device comprises a common pinch roll;
- said means for retracting first and then lifting the upper table comprise at least one hydraulic or pneumatic cylinder for retracting the upper table and at least one hydraulic or pneumatic cylinder for lifting the upper table, said last cylinders being located near the joining device;
- the hydraulic or pneumatic cylinders are partially or totally replaced by screws actuated by electric or hydraulic motors;
- the equipment comprises a non-contact detection means for controlling the height of the loop at the lower table and preventing a collision of said loop with the upper table ;
- the non-contact detection means is a light barrier;
- the equipment comprises a pivotable strip centering wheel able to be moved to the strip by a hydraulic or pneumatic cylinder.
[0016] A second object of the present invention relates to a method for joining, centering and butt welding two strips, in an entry section of a continuous industrial equipment, comprising all characteristics of claims 1 to 8, characterized at least by the following steps:
- a running coil N is processed through the lower entry level;
- a next coil N+1 is threaded, prepared, and cropped on the upper entry level, the head end thereof being placed in front of the common pinch roll in a waiting position;
- the tail end of coil N successively leaves the pay-off reel mandrel, the lower entry level and the common pinch roll, a loop being created at the exit side of the welder for centering the tail end;
- immediately after that the common pinch roll is free, the head end of coil N+1 at the upper entry level is threaded by the common pinch roll to the entry side of the welder;
- according to speed differences between the upper entry level and the common pinch roll a loop is created at the upper transfer table ;
- after creation of the loop, the top roll of the common pinch roll is retracted to allow the movement of the strip during a centering process;
- the tail end of coil N and the head end of coil N+1 are butt welded at the welder ;
- the new coil N+1 is further fed to the line via the upper entry level;
- a next coil N+2 is threaded, prepared, and cropped on the lower entry level, the head end thereof being placed in front of the common pinch roll in a waiting position ;
- the tail end of coil N+1 leaves the pay-off reel mandrel, the upper entry level and the common pinch roll, a loop being created at the exit side of the welder for centering the tail end ;
- immediately after that the common pinch roll is free, the head end of coil N+2 at the lower level is threaded by the common pinch roll to the entry side of the welder ;
- to allow creation of a high loop for performing a safe centering function, the top transfer table is retracted and lifted upwards by the hydraulic or pneumatic cylinders and/or by the actuated screws;
- according to speed differences between the entry level and the common pinch roll, a loop is created at the bottom transfer table ;
- after creation of the loop, the top roll of the common pinch roll is retracted to allow the movement of the strip during a centering process;
- the tail end of coil N+1 and the head end of coil N+2 are butt welded at the welder;
- the new coil N+2 is further fed to the line via the bottom entry level.
Short description of the drawings
[0017] FIG.1 represents a typical layout of an entry section according to prior art, as far as hot rolled material is concerned.
[0019] FIG.3 represents a preferred embodiment of an entry section layout according to the present invention.
Detailed description of the invention and preferred embodiments
[0020] In order to reduce the entry cycle as described above, a new concept of looping table is developed according the present invention. The design with two transfer tables 3a, 3b (one for each pass line), a common pinch roll 4 and a looping table 5 (as in FIG. 2) is replaced by a design with only two transfer tables 3a, 3b including a looping function 5 and a common pinch roll 4. Accordingly, the loops for strip centering are made directly on the transfer tables. A schematic of the new solution is presented in FIG. 3. The scope of the present invention relates to an installation comprising any suitable welder 6. It is to be noted that the welder illustrated in FIG. 3 is an example of a commercially available welder.
[0021] According to a preferred embodiment of the invention, and in order to provide sufficient space to create a loop at the lower pass line, the upper looping table is retractable and can be lifted. When a loop has to be created on the lower pass line, the upper table is preferably first retracted by a hydraulic or pneumatic cylinder and then lifted by two hydraulic or pneumatic cylinders situated near the common pinch roll.
[0023] In more details, the method for joining, centering and butt welding two strip ends is as follows.
[0024] A running coil N (N integer >0) is processed through the bottom or lower entry level, comprising the lower table. The next coil N+1 is threaded, prepared, and cropped at the shear on the upper or top entry level, comprising the upper table. The new head end of coil N+1 is placed in front of the common pinch roll in a waiting position. The tail end of coil N successively leaves the pay-off reel mandrel, the bottom entry level and the common pinch roll, a loop being created at the exit side of the welder by two loop rolls (not shown) for centering the tail end.
[0025] As a new feature of this invention, the upper threading table combines three functions. The first one is to store the head end of next coil N+1, already close to the common pinch roll of the welder. The second function is to create a loop on this table. The third function is to allow the strip threading of strip N+2 to the common pinch roll during the loop creation and welding of strip N+1 in the shadow time of the welding process.
[0026] Immediately after the common pinch roll is free, the new head end of the coil N+1 at the upper entry level is threaded by the common pinch roll to the entry side of the welder. According to speed difference between the upper entry level and the common pinch roll, a loop is created at the top transfer table. After creation of the loop, the top roll of the common pinch roll is retracted by long stroke cylinders (not shown), to allow the movement of the strip during the centering process.
[0027] For further improvement of the centering process and to prevent blocking of the strip (especially for thick and hard materials) against the upper common pinch roll, a special pivotable centering wheel 7 will be moved to the strip by a hydraulic or pneumatic cylinder. This allows a better movement of the loop during the centering process with the integrated centering device of the welder. With this equipment, the accuracy of weld seam centering can be improved to reduce further problems during strip tracking, side trimming and cold rolling. After the centering, the pivotable centering wheel 7 will be retracted to allow the transport of the strip during further welding and notching accelerations.
[0029] The new coil N+1 is further fed to the line via the upper entry level. The next coil N+2 is threaded, prepared, and cropped at the shear on the lower entry level. The new head end of coil N+2 is placed in front of the common pinch roll in a waiting position. The tail end of coil N+1 successively leaves the pay-off reel mandrel, the upper entry level and the common pinch roll, a loop being created at the exit side of the welder by two loop rolls (not shown) for centering the tail end. Immediately after the common pinch roll is free, the new head end of the coil N+2 at the lower level is threaded by the common pinch roll to the entry side of the welder. So, it is necessary to allow the creation of a high loop for performing a safe centering function. For that reason, the top transfer table is retracted and lifted upwards thanks to the hydraulic or pneumatic cylinders. To prevent the collision of the loop with the upper threading table, the height of the loop will be preferably controlled by a light barrier. According to speed differences between the entry level and the common pinch roll, a loop is created at the bottom transfer table. After creation of the loop, the top roll of the common pinch roll is retracted by the long stroke cylinders, to allow the movement of the strip during the centering process. The considerations of § [0027] are also applicable here.
[0030] The tail end of coil N+1 and the head end of coil N+2 are then butt welded at the welder. The new coil N+2 is further fed to the line via the lower entry level.
[0031] Successive new coils are processed alternately in the lower and upper entry sections, with successive loops created alternately on the lower and upper entry tables.
[0032] In difference with other strip processing lines like CAL and CGL, the line according to the invention can also process thick hot rolled strips.
[0033] Thanks to this new concept, the looping table according prior art can be eliminated, and therefore the time-to-transfer of the strip from the common pinch roll to the welder is eliminated as well. Depending on the strip thickness, the time gain is typically between 5 and 7 seconds for each entry cycle time. As an example, this new entry design thus allows reducing the production time by roughly 2% (meaning increase in productivity) for a PL/TCM of 2 million tons capacity, depending however on incoming coils and line configuration.
[0034] In addition, this invention has the advantage of allowing a better loop creation. Thanks to the additional provision of the retractable upper' table and the centering wheel a better centering for heavy gages is possible.
List of references
1. A continuous industrial equipment having an entry section comprising two uncoiling
devices (1a, 1b) for uncoiling and feeding out strip materials to be processed, a
cutting device (2a, 2b) and a transfer table (3a, 3b) for each strip, and a joining
device (4), so that the transfer tables (3a, 3b) deliver said strips to the joining
device (4) where a coil tail strip and a coil head strip are joined, at least a looping
table (5) for strip centering and a welder (6) where said coil tail strip and said
coil head strip are butt welded, characterized in that each of the transfer tables (3a, 3b) is also a looping table (5).
2. The equipment according to claim 1, characterized in that it is provided so as the joined strips at the joining device (4) are directly fed
to the welder (6), without further looping.
3. The equipment according to claim 1, characterized in that, the transfer tables (3a, 3b, 5) consisting in an upper table (3a) defining an upper
entry level being superimposed on a lower table (3b) defining a lower entry level,
the equipment is provided with means for retracting first and then lifting the upper
table (3a).
4. The equipment according to claim 1, characterized in that each uncoiling devices (1a, 1b) comprises a pay-off reel.
5. The equipment according to claim 1, characterized in that each cutting device (2a, 2b) comprises a shear.
6. The equipment according to claim 1, characterized in that the joining device (4) comprises a common pinch roll.
7. The equipment according to claim 3, characterized in that said means comprise at least one hydraulic or pneumatic cylinder for retracting the
upper table (3a) and at least one hydraulic or pneumatic cylinder for lifting the
upper table (3b), the last cylinder(s) being located near the joining device (4).
8. The equipment according to claim 7, characterized in that the hydraulic or pneumatic cylinders are partially or totally replaced by screws
actuated by electric or hydraulic motors.
9. The equipment according to claim 3, characterized in that it comprises a non-contact detection means for controlling the height of the loop
at the lower table (3b) and preventing a collision of said loop with the upper table
(3a).
10. The equipment according to claim 9, characterized in that the non-contact detection means is a light barrier.
11. The equipment according to claim 1, characterized in that it comprises a pivotable strip centering wheel (7) able to be moved to the strip
by a hydraulic or pneumatic cylinder.
12. A method for joining, centering and butt welding two strips, in an entry section of
a continuous industrial equipment, comprising all characteristics of claims 1 to 8,
characterized at least by the following steps:
- a running coil N is processed through the lower entry level;
- a next coil N+1 is threaded, prepared, and cropped on the upper entry level, the head end thereof being placed in front of the common pinch roll in a waiting position;
- the tail end of coil N successively leaves the pay-off reel mandrel, the lower entry level and the common pinch roll, a loop being created at the exit side of the welder for centering the tail end;
- immediately after that the common pinch roll is free, the head end of coil N+1 at the upper entry level is threaded by the common pinch roll to the entry side of the welder;
- according to speed differences between the upper entry level and the common pinch roll a loop is created at the upper transfer table;
- after creation of the loop, the top roll of the common pinch roll is retracted to allow the movement of the strip during a centering process;
- the tail end of coil N and the head end of coil N+1 are butt welded at the welder;
- the new coil N+1 is further fed to the line via the upper entry level;
- a next coil N+2 is threaded, prepared, and cropped on the lower entry level, the head end thereof being placed in front of the common pinch roll in a waiting position;
- the tail end of coil N+1 leaves the pay-off reel mandrel, the upper entry level and the common pinch roll, a loop being created at the exit side of the welder for centering the tail end;
- immediately after that the common pinch roll is free, the head end of coil N+2 at the lower level is threaded by the common pinch roll to the entry side of the welder;
- to allow creation of a high loop for performing a safe centering function, the top transfer table is retracted and lifted upwards by the hydraulic or pneumatic cylinders and/or by the actuated screws;
- according to speed differences between the entry level and the common pinch roll, a loop is created at the bottom transfer table ;
- after creation of the loop, the top roll of the common pinch roll is retracted to allow the movement of the strip during a centering process;
- the tail end of coil N+1 and the head end of coil N+2 are butt welded at the welder;
- the new coil N+2 is further fed to the line via the bottom entry level.