Patent GB-996831-A (GB)
Title: An edge trimming machine for sheet metal parts
IPC: B23D33/02
Filed: 1963-04-11
Abstract: 996,831. Trimming. ELEALOR A.G., FABRIK FUR ELEKTROTHERMISCHE APPARATE. April 11, 1963 [April 16, 1962], No. 14538/63. Heading B3W. An edge trimming machine for the rims of sheet metal parts comprises first and second platens to which cutting tools are clamped, hydraulically operated means for reciprocating the first platen relative to the second platen, stops for determining the relative positions of the platens and means for giving the second platen a combined translatory and swivelling motion. A cover-plate 1 with a rim 2 is placed on the lower platen 4 inside a cutting frame 3 and the upper platen 6 which carries a cutting frame 5 is lowered to the position shown in Fig. 4 and held in this position while the lower platen 4 is moved horizontally to produce a shearing action between the cutting frames. The horizontal movement of the platen 4 includes a rotary component which is produced by connecting the platen by links 7a, 7b, 7c to eccentrics so that the platen has the motion indicated in Fig. 5. The frame of the machine comprises a lower casing 12, columns 13 and an upper casing 14 which contains a motordriven pump 24, an oil tank 25 and a valve set 26. The upper platen slides on the columns and its lower position is determined by threaded rings 28 which carry a micrometer scale 29. The pump 24 delivers a large volume of low pressure oil to move the upper platen to its lower position and then automatically changes to a low-volume high-pressure range to prevent upward movement of the platen 6 during cutting. The lower platen 4 rests on low-friction bearings 34 in a recess 33 in the lower casing 12 and is connected by the links 7a, 7b or 7c to eccentric portions 42a, 42b and 42c on vertical shafts 44a, 44b and 44c. The shaft 44c has freely mounted thereon a gear-wheel 46c which can be locked to the shaft by a rotatable key 64c which carries a radial finger 65c. The finger is biased by a spring 67c to rotate the key to a position in which it engages a recess 70c in the gear-wheel, but can be prevented from moving by an abutment 68c. The gear-wheels 46a and 46b have similar clutches controlled by abutments 68a and 68b. The gear-wheels 44 are driven by a motor 54 through a belt 51 and pinion 48. The gears are meshed so that the recess 70b lags 60 degrees behind the recess 70a and the recess 70c lags a further 60 degrees behind the recess 70b, so that there is a corresponding angular interval in the commencement of rotation of the shafts. To start the cycle of operation the platen 6 is lowered and when the necessary hold-down pressure has been reached an electromagnet 89 rotates a tube 80 and withdraws the abutment 68a to release the key 64a. As the gear-wheel 44a rotates a cam 87 through a roller follower 86 and a lever 84 operates a link 82 and rotates a shaft 71, which carries the abutment 68b, and is connected by a second link 79 to a shaft 72 which carries the abutment 68c. As the shaft 71 rotates an adjustable stop 98 strikes a limit switch 99 and de-energizes the electromagnet 89 so that the key 64a is disengaged after one revolution of the gear-wheel 44a. The cam 87 holds the link 82 and the shaft 71 in a position to keep the abutments 68b and 68c clear of the fingers 65b and 65c until the gear-wheels 46b and 46c have rotated sufficiently (60 degrees and 120 degrees) for the keys 64b and 64c and engage their respective gear-wheels.