GB2161734A

GB2161734A - Billet shearing method and apparatus

Info

Publication number: GB2161734A
Application number: GB08508912A
Authority: GB
Inventors: Dieter Volksheimer
Original assignee: Eumuco AG fuer Maschinenbau
Current assignee: Eumuco AG fuer Maschinenbau
Priority date: 1984-04-14
Filing date: 1985-04-04
Publication date: 1986-01-22
Also published as: GB8508912D0; GB2161734B; IT8520218A0; JPS60232813A; IT1184378B; JPH01127216A; JPH0418964B2

Abstract

For obtaining accurately cut lengths of material from a billet 11, such cut lengths being intended for use as blanks for subsequent solid-forming operations, an axially movable feed device 14 feeds the billet 11 from a roller table 21 into a shearing station provided with shear blades 5 and 8. A two-stage device 9 applies a lesser clamping force against a lower blade holder 4 via a roller 28 during guiding of the billet 11 through the shearing station, and a larger clamping force during shearing. The feed device 14 maintains a constant feeding force on the billet 11, and the adjustment of the stroke limitation of the axially movable billet 11, via a steplessly adjustable device 39 with a servo motor 40, is coupled with the feed device 14. Additional gripper 30, mounted at the shearing station 1 to grip the billet 11 during the shearing stroke, is mounted on return springs 34 and 35 to absorb axial movement of the billet clamping shearing. The roller table 21 can be raised by tipping cylinder 23. <IMAGE>

Description

SPECIFICATION Billet shearing method and apparatus This invention relates to a shearing method and apparatus for obtaining accurately cut lengths of material from shearable material, such as rolled steel, bar and billets, such cut lengths being intended for use as blanks for subsequent solidforming operations.

For convenience hereinafter the term "billet" will be employed, though it should be understood that the invention is applicable generally for obtaining accurately cut lengths of material from shearable metallic material.

The invention has been developed primarily, though not exclusively, with a view to improving the method and apparatus disclosed in our G.B.

application No. 8326412 (Published under No. 2 129 356A on 16th May 1984, which is after the priority date, 14th April 1984, of the present application), so as to obtain more exact sheared lengths of material from a billet.

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 cutting-off processes like sawing, burning, breaking and the like.

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 1 4%. Since such variations can lead to disturbances with subsequent manufacturing steps, like wrongly shaped parts, excessive tool wear, the 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 the clampabutment or the lower blade into the working space of the shears. Through contact closing 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.

Since the volume variations are caused in the entire system of the shearing, namely the feeding of the material, clamping and stopping, it has been proposed that after the lining-up of the billet or the like into the working space of the shears, the shearing plane remains unchanged. The feeding of the billet is effected compulsorily with constant feed force. Furthermore the billet is held pressed under a clamping effect of predetermined force on the clamp-abutment during this feed process. The fixing of the billet is carried out by a clamping force of greater proportions.Since the billet or the like is held and guided during travel to the stop in a reliable and compulsory manner, the other disturbance sources, e.g. change 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.

During its travel to the stop, the billet is controlled and guided in a satisfactory manner. In this way a volume tolerance can be lowered clearly below + 0.5%. The prerequisite for an exact and burr-less forging is created. The 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 the stop on the delivery side of the same, whereby the feed is produced by consequence of this is substantially lower measurement variations of the parts, which makes possible the production of pre-assembled functional surfaces without any subsequent work. There is a weight saving when forging without a burr gap with respect to forging with a burr. A greater durability is obtained for the forged part. It has been seen that when shear-cutting there is still a plastic deformation to the left and the right in the region of the shearing plane caused by the contact of the blade and this can be clearly seen both at the end of the ingot and also on the opposite rod end.The plastic deformation occurs in the transverse direction or the radial direction of the rod, and hence the material is also displaced in the axial direction with the consequence that there is an elongation.

Therefore with a shearing cut both the ingot and the rod move in the axially opposite direction.

However, the plastic deformation is not constant and is in fact dependent on the material and its stability. Since the billets are thermally untreated material from the bloom path, within a length of billet there can also be seen different structural states and hence different stabilities. Insofar as the plastic deformation near the shearing blade has a different order of magnitude dependent on the stability, this has negative effects as regards achieving a division that is as constant as possible with respect to volume.

The invention seeks to eliminate or lessen the disadvantages of plastic deformation occurring in the billets to be sheared, by an improved operation and a different construction of the feed device. The invention is characterised by the fact that the adjustment of the stroke limited of the axially movable billet is coupled with the feed device which applies a compulsorily constant feed force, and by the fact that the fed billet is held firmly in its shearing position in the axial direction.

In this way the influence of different plastic deformation during cutting can be eliminated in the adjustment of the cut length. A different plastic de formation consequently has appropriate return movements according to the type of retaining of the billet or the billet end, with the result that the cut length undergoes a greater tolerance, but the volume constancy of the ingot to be sheared is improved by the influence of the plastic deformation.

According to the device, the construction of the billet shears of the invention is such that instead of a stop device for the billet rod there are arranged fixedly mounted pincers gripping the billet, the pincer jaws of which in the axial direction are under the effect of a spring. The fed billet is held firmly in its shearing position with these fixed pincers. The pincer jaws on the fixed pincers are under the effect of return springs. These return springs take up the axial movement of the rod which occurs during the shearing cutting.

The axially movable feed pincers are provided with a step-lessly adjustable stroke limitation device, with which the ingot length to be sheared can be adjusted. On the movable feed pincers, initial tensions are also advisable to make possible a clearance-free grip in the starting position.

The return springs have a double function. On the one hand they ensure that the rod can be axially compensated during the shearing cutting so that they can again take up their original position afterwards. In addition the return springs make sure that the fixed pincers grip the rod material in the clearance-free starting position with respect to the entire system.

The invention will be described in more detail by means of an embodiment shown in the drawing.

Parts of the shearing method and apparatus disclosed herein are described in more detail in the specification and drawing of our prior G.B. application 8326412 (Publication No. 2 129 356A), and to which attention is drawn.

In the above application, there is disclosed generally a method for obtaining accurately cut lengths produced by shearing steel, bar and billet material for us as blanks for solid-forming, in which the beginning of the billet of the like is transported through shears at a shearing station, after a short lift to the shearing plane by raising the billet on a roller table, whereupon the billet is pressed by means of a clamp against an abutment while the shearing stroke is initiated, whereby after the lining-up of the billet into the working space of the shear the shearing plane remains unchanged, the feeding of the billet is maintained compulsorily with constant feed force, the billet is held pressed onto the clamp-abutment during the feeding process under a clamping effect of predetermined proportions, and the fixing of the billet is carried out with a clamping force of greater proportion while the shearing stroke is completed.

There is also disclosed generally in the previous application billet shearing apparatus for obtaining accurately cut lengths produced by shearing steel, bar and billet material, in which the billet or the like is transported by means of a driven roller table through the working space of the shears, whereby for lining-up, the roller table is lifted and then lowered again, and the shearing stroke is initiated after the billet has been fixed by the clamp against the clamp-abutment, whereby there is provided as a further transport device a feed device acting with constant feed force along the shearing plane.

As will become apparent from the subsequent detailed description of the method and apparatus according to the present invention, there is disclosed herein improvement to the method and apparatus disclosed in our previous application. In particular, the method is improved by arranging for the adjustment of the stroke limitation of the axially movable billet to be coupled with the feed device which applies the compulsorily maintained constant feeding force, and arranging for the fed billet to be held fixedly in the axial direction in its shearing position.

Additionally, the shearing apparatus disclosed in our earlier application is improved by arranging fixedly mounted pincers to grip the billet, the jaws of which are spring biased in the axial direction of the billet.

Referring now to the accompanying drawing, the single Figure shows a hydraulically driven billet shears which incorporates an improved feeding arrangement for supplying a billet to the shears in order to obtain more accurately cut lengths. The single Figure is a schematic side view, partially in section.

On the run-in side of the shearing station there is disposed a feed device 14 for feeding a billet 11 through the shearing station, as will be described in more detail below. On the run-in side of the feed device 14 there is provided a roller table 21 with rollers 22. The billet 11 has sharp side edges by which it is accurately received within guiding parts of the rollers 22, and the rollers are driven in order to feed the billet 11 to the feed device 14. A lifting cylinder 23 is provided for raising the table 21 to the shearing plane, so that the billet 11 can run freely along the shearing plane and through the shearing station. Resilient buffers 24 are provided to support the roller table 21.

The shearing station is provided within a set of billet shears 1 which comprises two posts 2 between which there are disposed a drive cylinder 3 and a lower blade holder 4 which carries a lower shearing blade 5, and these parts form a fixed structural unit. The blade holder 4 is used at the same time as a clamp-abutment when the billet 11 is fed through the shearing station. The drive cylinder 3 has a drive system 6 which is provided with an upper blade holder 7 carrying an upper shear blade 8. Within the drive piston 6 there is arranged a further drive piston 6a for operating a clamp 9.

On the lower blade holder 4 there is provided a counter holding device 4a which is constructed in the lower part as a cylinder and which cooperates with a fixed piston 4b.

The clamp 9 is provided with at least two power stages. One power stage is used for fixing the billet 11 during the shearing process, and this is operated by the piston 6a. A further power stage of lesser force effect is formed by a piston-cylinder unit 25 having a piston 26 which applies a partial clamping force on the billet 11 by means of a pis ton rod 27, preferably acting through at least one roller 28, whereby a slidable engagement occurs on the billet 11 during feeding through the shearing station. The further clamping device 25, namely the piston- cylinder unit, can be actuated by a suitable 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, whereby the billet is kept pressed against the clamp-abutment provided by counter holding device 4a and piston 4b, during feeding of the billet.

As referred to above, there is provided on the run-in side of the shears 1 the feed device 14, which has clamping jaws 15, 16 thus form pincers which firmly grip the billet 11 with a constant force. A support 20 is provided for supporting the 14.

Unlike the arrangement disclosed in our above mentioned application, the billet shears 1 herein have no stop device for engaging the leading end of the billet 11 as it passes through the shearing station. Instead of this, the feeding arrangement for the billet 11 is provided with other functions.

First of all, the feed arrangement includes additional means for gripping the billet, taking the form of additional pincers 30 which are, in principle, fixedly arranged. The pincers 30 are mounted on a shaft 31, and have clamping jaws 32 and 33 for engaging the billet 11. However, springs 34 and 35 are provided, which react from a bow-shaped part 36 of a main holding part 37 for the feed device 14, the springs 34 and 35 acting on the clamping jaws 32 and 33 in the axial direction of the billet 11 as return springs.

The feed device 14 is, as mentioned above, mounted on holding device 37, and is able to carry out axial movement relative thereto, as axially movable feed pincers for the billet 11.

The actuation of the jaws 32 and 33 of the fixedly mounted pincers 32 is effected preferably by hydraulic or pneumatic means.

The axially movable feed device 14 advantageously is provided with a steplessly adjustable stroke limitation device 39 having a servo motor 40, whereby the length of the ingot or billet to be sheared can be adjusted. The clamping jaws 15 and 16 of the movable feed device (pincers) 14 are preferably also provided with initial spring biasing by springs 41 and 42, which make possible clearance-free gripping in the starting position.

The return springs 34 and 35 for the fixedly attached pincers 30 are able to absorb the axial movement of the billet (rod) which takes place during a shearing stroke. The billet can be axially compensated after the shearing stroke, so as to take up its original position. The different plastic deformations of the billet merely result in corresponding return movements of the fixed pincers 30. Also, the return springs 41 and 42 of the feed pincers 14 make possible a clearance-free gripping in the starting position.

When the movable shear blade 8 has been withdrawn, the return springs again push the billet back into the original position. Not until this return movement has been carried out do the axially movable feed pincers 14 close and, after the fixed pincers 30 have opened, the movable pincers feed 14 moves into the shearing position with the billet 11. Then the fixed pincers 30 close and the movable feed pincers 14 open and move back into their starting position.

Claims

1. A shearing method for obtaining accurately cut lengths of material from a supply of shearable metallic material (referred to herein as a "billet" for convenience), such cut lengths being intended for use as blanks for subsequent solid-forming operations, the method comprising: operating a feeding device to axially transport the leading end of the billet through shears at a shearing station by an amount appropriate to the required length to be cut, and pressing the billet by means of a clamp against an abutment whilst a shearing stroke is initiated, whereby after the lining-up of the billet into the working space of the shear the shearing plane remains unchanged, the feeding force applied by the feeding device to the billet is maintained compulsorily substantially constant, the billet is held pressed onto the clampabutment during the axial feeding of the billet, and the billet is fixed in position with a greater clamping force while shearing is completed, in which: the adjustment of the stroke limitation of the axially movable billet is coupled with the feeding device which maintains the substantially constant compulsory feeding force; and the fed billet is held fixedly in the axial direction, when in its shearing position.

2. Shearing apparatus for obtaining accurately cut lengths of material from a supply of shearable metallic material (referred to herein as a "billet" for convenience), such cut lengths being intended for use as blanks for subsequent solid-forming operations, the apparatus comprising: a shearing station, a roller table on the run- in side of the shearing station for supplying a billet to the shearing station, the roller table being movable upwardly to the level of the shearing plane so as to present a billet to be fed to the shearing station, a clamp-abutment device provided at the shearing station for holding the billet when a shearing stroke is initiated, and a feeding device for transferring the billet from the roller table and feeding the billet by the required amount along the shearing plane to the shearing station, the feeding device being operable to maintain a compulsorily constant feeding force along the shearing plane, in which: fixedly mounted pincers are provided at the shearing station for gripping the billet, the pincers having jaws which are movable under spring action in the axial direction of the billet.

3. Apparatus according to claim 2, in which the feeding device comprises axially movable feed pincers having a steplessly adjustable stroke limitation device with a servo motor,to enable adjustment in the length of material to be sheared from the billet.

4. Apparatus according to claim 2 or 3, in which the fixed pincers are pivotally mounted at the shearing station.

5. Apparatus according to claim 3, or claim 4 when appendent to claim 3, in which the axially movable feed pincers include jaws which are acted upon by springs in the axial direction of the billet.

6. Apparatus according to any one of claims 2 to 5, in which return springs are provided which act on the jaws of the fixed pincers, said springs acting against a fixed holding device on which the feed device is axially movably mounted.

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

8. Apparatus according to claim 2 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.