Patent GB-1431337-A (GB)
Title: Shearing machines
IPC: B23D23/00
Filed: 1973-04-06
Abstract: 1431337 Shearing ZDARSKE STROJIRNY A SLEVARNY NARODNI PODNIK 6 April 1973 [6 April. 1972] 16507/73 Heading B3W A shearing machine comprises a frame 2 pivotable about a pin 25 on a fixed frame 1, the frames 1, 2 carrying a pair of vertically aligned blades 6, 8 and 5, 7 respectively, preferably shaped to cut transversely several profiled sections 60 placed side-by-side. The frame 2 is also supported by springs 36 which tend to lift the frame about pivot 25 so that its lower blade 5 is higher than, and laterally displaced relative to, the lower blade 6 of the fixed frame 1 for easy introduction of the sections into the shear. An hydraulic cylinder 38 is actuatable to level the frame 2. The upper blade 7 of the frame 2 is mounted in a support 3 slidable by means of a toggle 30 in a guide, in the fixed frame, which is inclined to the web of the sections 60 at an angle which is >70 and <90 degrees. The toggle 30 is connected to a lever 26 pivoted to the frame 2 at 27 and to the drive-transmission rod 29 at 28. An hydraulic cylinder 35 for actuating the toggle is also pivoted to the lever 26. The upper blade 8 of the fixed frame is mounted in a support 4 slidable by means of an hydraulic cylinder 46 in a guide inclined in the opposite sense to the guide of support 3 and at an angle which is >90 and <110 degrees. A spring- loaded bolt (55), Fig. 7 (not shown), biases the supports 3 and 4 apart. Means 41-44 are provided on each blade holder for maintaining the selected degree of play, adjusted by set screws 45, between the blades and absorbing expansion forces during shearing. In operation, profiled sections 60 are fed by a conveyer into the shear with the frame 2 raised by springs 36. At the end of the feed stage, lowering of the conveyer causes a signal to start the shearing operation. First, the cylinder 38 is actuated to level the frame 2, then the cylinder 46 is actuated to lower the blade 8 to clamp the sections 60 against the blade 6 and the cylinder 35 via the toggle 30 moves the blade 7 to a position a few mms. above the sections 60, the supports 3 and 4 closing limit switches (47), (48), Fig. 2, which initiates a shearing stroke by the rod 29. First the blade 7 is lowered on to the stock and then the frame 2 is pivoted downwardly about pin 25 and the stock is sheared. The drive to the rod 29 may be an hydraulic cylinder or a crank-shaft. For shearing light-weight sections, the lever 26 may be immobilized in a position leaving the last part of the toggle-straightening stroke to carry out the shearing. Alternatively the toggle may not be straightened completely in moving the blade 7 close to the stock and acts as a safety device against overloading during shearing by the lever 26. For shearing solid rolled sections or angle iron, the frame 2 is prevented from pivoting by a bolt (52) in the form of a displaceable hydraulic cylinder, Fig. 7 (not shown), mounted in the frame 1, which is urged into a socket in the frame 2, the frames having been aligned by the cylinder 38. The straightened toggle transmits shearing force from the rod 29 to the blade 7 via blade support 3. For this use of the shear, a hold down replaces the blade 8 and the lower blade 5 is dispensed with. The remaining blades may be straight-edged.