GB2129356A

GB2129356A - Billet shearing method and apparatus

Info

Publication number: GB2129356A
Application number: GB08326412A
Authority: GB
Inventors: Dieter Volksheimer; Gottfried Hartke
Original assignee: Eumuco AG fuer Maschinenbau
Current assignee: Eumuco AG fuer Maschinenbau
Priority date: 1982-10-28
Filing date: 1983-10-03
Publication date: 1984-05-16
Also published as: IT8323491A0; IT1169620B; DE3239899A1; JPH0160371B2; FR2535233A1; DE3239899C2; FR2535233B1; JPS5993219A; GB8326412D0; GB2129356B

Abstract

The method and apparatus is for obtaining exact sheared lengths from steel billet material 11 for use as blanks for solid-forming. After raising of the billet 11 on a roller table 21 by means 23 to line-up with a feed path to shear blades 5 and 8, the billet is advanced by the roller table 21 and by a gripper feed device 14 until it engages an adjustable stop 13. During the feeding step, a partial clamping force is applied to the billet by a clamping device 25 acting via a roller 28. When the billet engages the stop (13), a greater clamping force is applied to the billet, to fix it in the shearing position, by means of a hold down 9. A shearing stroke is initiated upon engagement taking place between the leading end of the billet and the stop. The fact that the shearing plane remains unchanged after lining-up of the billet, and that the billet is fed right up to the stop with a constant feed force contributes to accuracy of the lengths sheared. <IMAGE>

Description

SPECIFICATION Billet-shearing method and apparatus This invention relates to a method and apparatus for obtaining exact sheared lengths from steel bar, billet or the like material (referred to hereinafter as billet material) for use as blanks for solid-forming.

Blanks for solid-forming are produced for the main part by shearing steel-, bar- or billet material, since this is a cutting-off process which has no material wastage. In addition the output is substantially greater than with the other cuttingoff processes like sawing, burning, breaking and the like.

There are known measuring processes which make it possible to determine the dimensions of the billets before or after shearing in order to then divide them into equal volume cuttings. However, such methods are only convenient when the cutting lengths determined in accordance with a desired volume can be accurately observed.

For reasons of cost, efforts are made as far as possible to process billets, i.e. material from the bloom path. When using conventional shearing equipment there are, however, volume variations up to about +4%. Since such variations can lead to disturbances with subsequent manufacturing steps, like wrongly shaped parts, excessive tool wear, tool- and machine overload and the like, it is imperative to eliminate volume variations. The bulk scattering occurring during shear cutting on the cut-off ingots is thus caused on the one hand by the large tolerance of the semi-finished material (billet) and on the other hand by influences of the machine and the tool.

When adjusting the lengths of the cuttings to be sheared, it is known to transport the billet or the like by means of a roller table through the shears and up to a stop on the delivery side of the same, whereby the feed is produced by driven rollers of the roller table. In order to be able to feed the billet, generally the rolling plane of the roller table is raised so far that the billet can run without friction between a clamp-abutment provided in the shears, or the lower blade into the working space of the shears. Upon contact between the stop and the billet, the shearing force is then initiated. Before the cutting, the clamp is actuated and the roller table is lowered in order to protect it from impacts on the billet caused by the shearing process.In addition the stop is withdrawn during the cutting in order to prevent a jamming of the sheared-off cuttings between the stop and the blade. Thus the billet or the like can not be prevented from changing position even in the billet axis direction during lowering of the roller table.

In addition there can occur a discrepancy through the fact that in the raised position of the roller table, the contact surface of the stop to the billet lies optionally in the non plane fraction surface of the shearing surface, whereby the position of the contact surface shifts during lowering of the roller table. The roughness of the fracture surface and the fracture path therefore have an influence on the length of the cutting. In addition the press force of the billet on the stop and hence its resilience, clearance etc. is dependent on the variable inherent weight of the billet and the coefficient of friction between the driven roller and the billet or the like.

With curved billets and the like and also with billet lengths that become shorter, there are position inaccuracies with respect to the stop during the lowering of the roller table which also lead to inaccuracies in the lengths of the cutting.

The feed force of the roller table changes during the placing of the billet on the clamp-abutment.

The placing occurs when there is a large amount of bend of the billets or the like or when there is an unfavourable position of the centre of gravity of the shortening billet ends. Also the roller clearance and the arrangement of the roller table rollers becomes effective in this connection.

Disruption in the amounts of influence on the machine side has resulted in the fact that even with a tool that has been adapted as well as possible and with a constant billet cross section with conventional shearing installations the necessary volume constancy of at the most ~0.5% particularly with shorter cuttings can not be achieved. In addition the measuring processes for determining the necessary cutting lengths require a specific tolerance field, so that the tolerance from the machine influence must clearly be below the maximum permitted volume tolerance.

The invention proceeds from the knowledge that these volume variations are caused in the entire system of the shearing, namely the feeding of the material, clamping and stopping. It is an aim of the invention to provide a shearing method and apparatus with which the volume variations mentioned can be reliably reduced to the necessary volume tolerance. A maximum volume tolerance of 0.5% is considered a prerequisite for volume-constant shearing cutting.The invention is distinguished, in the transport of the billet or the like, after the short lift movement, through the shears from the shearing plane to a stop on the delivery side of the shears, by means of a roller table, whereupon the billet or the like is pressed by means of a clamp against an abutment, and the shearing force is initiated by contact closing between the stop and the billet, by the fact that after the lining-up of the billet or the like into the working space of the shears, the shearing plane remains unchanged, the feed of the billet with constant feed force is necessarily carried out up to the stop, in that the billet is held pressed under a clamping effect of predetermined force on the clamp-abutment during this feed process, and in that the fixing of the billet is then carried out by a clamping force of greater proportions.

With the length adjustment of the cuttings of the invention, it is important that the shearing plane is not changed except with a short lining-up process. Rather is the billet or the like held and guided during travel to the stop in a reliable and compulsory manner, so that the other disturbance sources, e.g. changes in position of the billet or the like during lowering of the roller table, the changeable inherent weight of the billet to be sheared, the coefficient of friction between the driven roller and the billet, can safely be eliminated. The feed force is so measured that the transport of the billet is satisfactorily possible.

During its travel to the stop, the billet is controlled and guided in a satisfactory manner. It is made possible for the disadvantageous volume variations on the cuttings to be eliminated and to be lowered to a volume tolerance clearly below +0.5%. Hence there is created the prerequisite for an exact- and burr-less forging, whereby there are substantial advantages for the parts to be forged. Substantially lower measurement variations of the parts are obtained which makes possible the production of preassembled functional surfaces without any subsequent work. In addition there is a weight saving when forging without a burr gap with respect to forging with a burr. This has a better grain flow and thus there is a greater durability for the forged part.

After the cutting length adjustment has been carried out, the billet or the like is to be held clamped by the feed device with a constant feed force between the feed device and the stop until the clamping force of higher proportion becomes effective. The maximum possible feed path of the feed device with constant feed force is kept greater than the maximum length to be adjusted of the cutting to be sheared. This results in the security that the guiding of the billet and the like is maintained up to the stop, until the fixing of the billet or the like for the shearing process is carried out.

The construction of the billet shears is so designed according to a further feature of the invention that the clamp is provided with at least two power stages, one power stage of which takes over the guiding of the billet during positioning and the other power stage fixes the billet or the like during the shearing process. The further clamping device is preferably of lesser power effect than that of the clamp used for fixing the tool, whereby the further clamping device has an effect on the billet under slidable engagement during closure. The latter takes place preferably by means of at least one roller or the like, in order to keep as low as possible the friction forces counteracting the feed force during shifting of the billet.

The other clamping device can advantageously be installed in the clamping device used for fixing.

Thus it can be a piston-cylinder-unit actuated by a force means, e.g. hydraulically or pneumatically, whereby a specific elasticity in the pressing force can be made possible. A further feature of the invention is a feed device with constant feed force, preferably formed of pincers gripping the billet which can clamp the billet or the like with constant force, and takes over the feed after the roller table has stopped.

Since through the compulsory guiding of the billet during travel to the stop, the stop surface always hits the same surface in the shearing surface, this surface should be the flat intersection surface of the shearing surface, since only at this point can the section length be clearly adjusted. In order to keep the surface pressure between the stop and the billet as low as possible, the shape of the stop surface is to be adapted to that of the intersection surface.

Since the guiding of the billet or the like is carried out by means of the feed device with constant feed force and thus adjustment of the roller table as to height is no longer provided, the entire roller table is mounted on resilient buffers or the like, in order to protect it from shocks to the billet caused by the shearing process.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawing, which shows a hydraulically driven billet shears with a device for obtaining accurate cut lengths, in side view, partially in section and schematically represented.

With the shears 1 that are shown, between the two posts there is disposed a drive cylinder 3 and a lower blade holder 4 which carries a lower shearing blade 5, whereby these parts form a fixed structural unit. The blade holder 4 is used at the same time as a clamp-abutment. The drive cylinder 3 has a driven piston 6 which is provided with an upper blade holder 7 which carries an upper blade 8. The blades 5 and 8 define a shearing station through which a billet 11 is movable. In the drive piston 6 there is arranged a further drive piston 6a for a clamping device 9. On the lower blade holder 4 there is disposed a counter holding device 4a which is constructed in the lower part as a cylinder and co-operates with a fixed piston 4b.

On the run-out side of the shearing station there is provided a device 10 for the adjustment of the length of sections to be cut off from a billet 11, whereby the adjustment can preferably be carried out by means of a servo motor 12. On the length-adjustment device 10 there is disposed a stop 13 for the billet 1 A contact surface 1 3a of the stop 18 is adapted as regards position and shape to the intersection surface in the shearing surface. In addition to this, the length adjustment device 10 can be adjusted in height on a rail 1 Oa, and then stopped in a required position.

On the run-in side of the shears there is disposed a feed device 14 which has clamping jaws 15 and 16 which grip the billet 1 1 between them. The clamping jaws 15 and 16 are brought into the clamping position against the billet 1 1 by a piston-cylinder-unit 17 in conjunction with a linkage 18. The clamping jaws 15. 16 thus form a pincers which firmly grips the billet 11 with constant force. The cylinder 19 is used to exert forward feeding for the pincers 15, 16. 20 designates a support for the feed device 14.

On the run-in side of the feed device 14 there is provided a roller table 21 with rollers 22. On the driven rollers 22 of the roller table 21,the billet 11, which lies with sharp edges in the rollers 22 and the pincer parts 1 5, 16, is transported into the feed direction 14. In addition to this the roller table 21 is lifted so far by the lifting cylinder 23 that the billet 11 can run freely into the pressing chamber at the shearing station. Preferably the roller table 21 lies on resilient buffers 24.

The clamping device 9 is provided with at least two power stages. One power stage is used for fixing the billet 11 during the shearing process and is exerted by the piston 6a. A further power stage of lesser force effect is formed by a piston cylinder-unit 25 whose piston 26 applies a partial clamping force on the billet 11 by means of a piston rod 27, preferably by means of at least one roller 28, whereby a slidable engagement during closure occurs on the billet 11 or the like. The further clamping device 25, namely the pistoncylinder-unit, can be actuated by a force-applying means, e.g. hydraulically or pneumatically. The second power stage in the form of the clamping device 25 takes over the guiding of the billet 11 or the like during positioning on the stop surface 13a, whereby the billet is kept pressed against the clamp-abutment 4 during shifting.

The billet 11 or the like is held clamped by the feed device 14. 19 with constant feed force between this and the stop 13 after the cutting length adjustment has been carried out, until the clamping force of higher proportion becomes effective by means of the clamp 9, whereby the billet is fixed in the shearing position. Accordingly the feed device is brought back into the initial position after releasing of the clamping jaws 1 5 and 16 by the cylinder unit 19.

The roller table 21 is lifted so far by the lifting cylinder 23 that the billet can run freely into the pressing chamber. For the subsequent shearing processes inside the billet the roller table 21 remains without drive in the lowered position and it lies on the resilient buffers 24. The transport of the billet is thus taken over exclusively by the feed device 14.

Claims

1. A method of obtaining exact sheared lengths from steel billet material for use as blanks for solid-forming and comprising feeding the leading end of the billet through a shearing station to a stop on the run-out side of the shearing station and spaced therefrom by a distance corresponding to the required length to be sheared from the billet; clamping the billet in the shearing position; and initiating a shearing stroke at the shearing station upon engagement taking place between the leading end of the billet and the stop; in which the shearing plane of shears at the shearing station remains unchanged after lining-up of the billet into the working region of the shears; feeding of the billet is carried out by a constant feeding force up to the stop; the billet is pressed down under a partial clamping force of predetermined proportion during feeding up to the stop; and then the billet is clamped by a larger clamping force to fix it in the shearing position when the leading end of the billet engages the stop.

2. A method according to claim 1, in which the billet is lifted on a roller table prior to feeding to the stop.

3. A method according to claim 1 or 2, in which after cutting length adjustment has taken place, the billet or the like is held clamped by a feed device, which applies the constant feed force, between the feed device and the stop until the larger clamping force becomes effective.

4. A method according to claim 3, in which the maximum possible feed path of the feed device is greater than the maximum extent of adjustment of sheared length.

5. A method according to any one of the preceding claims, in which the partial clamping force becomes effective on the billet during positioning of the same.

6. A method according to claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.

7. Apparatus for shearing exact sheared lengths from steel billet for use as blanks for solidforming and comprising: a shearing station; a roller table operable to feed the leading end of a billet towards the shearing station; a stop arranged on the run-out side of the shearing station at a distance therefrom corresponding to the required length to be sheared, said stop serving to limit the feeding of the billet through the shearing station; means for clamping the billet in the shearing position; means for initiating a shearing stroke upon engagement taking place between the leading end of the billet and the stop; in which a feed device is provided which is operable, additionally to the roller table, in order to apply a constant feeding force to the billet to feed the latter through the shearing station; and the clamping means comprises first and second power stages, the first power stage being operable to apply a clamping force to the billet during feeding of the billet to the stop and the second power stage being operable to apply a clamping force to the billet, which fixes the billet in the shearing position, when the leading end of the billet has engaged the stop and a shearing stroke takes place.

8. Apparatus according to claim 7, in which the roller table is operable to raise the billet to line-up the billet with a feed path to the shearing station, and is thereafter returnable to its lowered position.

9. Apparatus according to claim 7 or 8, in which the first power stage of the clamping means includes a clamping device which is operable to apply a partial clamping force to the billet which permits relative slidable movement of the billet therewith as the billet moves to engagement with the stop.

10. Apparatus according to claim 9, in which the clamping device of the first power stage includes a roller for engaging with the surface of the billet.

11. Apparatus according to claim 9 or 10, in which the second power stage has a further clamping device which is operable to fix the billet in the shearing position, and said clamping device of the first power stage is housed in said further clamping device.

12. Apparatus according to any one of claims 9 to 11, in which the clamping device of the first power stage comprises a piston-cylinder unit.

13. Apparatus according to any one of claims 7 to 12, including means for adjusting the spacing of said stop from said shearing station, in which the feed path of the feed device is greater than the maximum adjusted spacing of the stop from the shearing station.

14. Apparatus according to any one of claims 7 to 13, in which the feed device is operative to apply the feeding force until the second power stage of the clamping means becomes effective.

15. Apparatus according to any one of claims 7 to 14, in which the feed device comprises a pincers arrangement for gripping the billet and for applying the constant feeding force to the billet after disconnection of the roller table.

1 6. Apparatus according to any one of claims 7 to 1 5, in which the engagement surface of the stop is adapted to the position and shape of the intersection surface in the shearing surface.

17. Apparatus according to any one of claims 7 to 16, in which the roller table is mounted on resilient buffers.

18. Apparatus according to claim 7 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.