Patent GB-746487-A (GB)
Title: Improvements in or relating to power presses
IPC: F16P3/24
Filed: 1953-04-30
Abstract: 746,487. Cutting-out presses. BRITISH UNITED SHOE MACHINERY CO., Ltd., and CHOICE, F. C. April 29, 1954 [April 30, 1953; June 25, 1953], Nos. 11918/53 and 17589/53. Class 31 (1). [Also in Group XXIV] A clicking press, such as described in Specification 538,763, [Group XXIV], having a cutting bed 10, Fig. 1, supporting a cutting block 12, a reciprocable presser arm 2 which is adapted to be swung over the block 12 about a vertical post 4, power means brought in by the operation of a clutch to reciprocate the presser arm and braking means to arrest such movement, is adapted to be controlled by two devices 42, 417 mounted on the presser arm, such as described in Specification 741,149, [Group XXIV], requiring both hands of the operator to be used in the operation thereof to effect engagement of the clutch. After a working stroke of the presser arm corresponding to a revolution of the machine shaft 8, the clutch is disengaged automatically and the brake applied so that the devices 42, 417 have to be released and operated again for another working stroke. The cutting bed 10 is adapted to be adjusted vertically by means of four screws 20, Fig. 4, arranged at the corners of the bed and actuated simultaneously by a hand wheel 38, worm gearing 32 and chain and sprocket gearing 30, 28. The clutch operating devices 42, 417 are coupled by linkwork passing through the presser arm 2 and down the vertical post 4 to the clutch and brake mechanism housed within a hollow box-like base 7 of the machine frame 5. The clutch and brake mechanism comprises, as shown in Fig. 8, a fly-wheel 208 belt-driven from a motor 214 (Fig. 1) which is adapted to be engaged by clutch shoes 224 mounted on a drum member 216 secured to the shaft 8 which carries an eccentric for effecting the reciprocation of the presser arm. The drum member 216 is also adapted to be engaged by a brake band 290 to stop the movement of the presser arm after each stroke. The clutch shoes 224 are adapted to be pressed into initial engagement by means of a radially arranged spring 270 acting through a lever 238, pivotally mounted on the drum 216, and toggle levers 230. Final engagement of the clutch is effected by a fixed cam 277 engaging a roller 272 on a slide 266 actuated by the spring 270 and engaging the clutch lever 238. The clutch is held out of engagement by a tripping member 278, pivoted at 288, engaging the roller 272. This tripping member is moved to release the roller 272 by release of a spring-loaded trigger lever 304 pivoted at 306 and coupled by a link 308 to member 278 but held inoperative by a trigger member 318 pivoted at 324 and having a nose-piece 316 engaging a catch piece 312 on the lever 304. The trigger lever 304 is also coupled to the ends of the brake band 290 so that when the clutch is disengaged the brake is engaged and vice versa. A loading spring 326 for the lever 304 is anchored to the trigger member 318 to keep it in operative position. In operation, when the two devices 42, 417 on the presser arm are actuated simultaneously, a a trip rod 332 is moved to the left through the linkage connections extending through the presser arm and down the vertical post to engage by a forward face 330 a plate 333 on the trigger member 318 to rock the latter to release the trigger lever 304. The latter moves downward under the loading of spring 326 until a projection 328 thereon engages a fixed abutment and in so doing releases the brake band 290 and swings the tripping member 278 away from the roller 272 to allow the spring 270 to effect initial engagement of the clutch. As the drum member 216 rotates with shaft 8, the cam 277 acting on roller 272 completes the clutch engagement and a working stroke of the presser arm is effected. In order to stop the presser arm after one stroke, the pivot 324 of the trigger member 318 is arranged on a block 320 on a crank-pin 322 on the end of shaft 8 so that as the shaft rotates, the member 318 is moved downwardly to re-stress spring 326 and then on its upward movement to re-engage the nose 316 with the catch 312 of trigger lever 304 to move the latter back to the original position which causes the brake band 290 to be applied and the tripping member 278 to move into the path of roller 272 to disengage the clutch. The downward movement of member 318 disengages its plate 333 from the face 330 of the trip rod 332 so that even if the trip rod 332 has not been returned the plate 333 will on its return upward movement only engage underneath the rod 332 which is free to be lifted. The rod 332 must therefore be restored and operated again to effect another working stroke. To ensure that the presser arm stops in the correct position after each stroke, a cam ring 356 on the shaft 8 controls a rod 336 which is also adapted to lift the trip rod 332 to an inoperative position except at one position of the shaft 8 provided by a'recess 354 in the ring 356. A modified clutch and brake mechanism is also described in which a spring-loaded bolt is arranged to slide in an axial direction on the clutch-driven member to effect the engagement and disengagement of clutch shoes and is controlled by a pivoted wedge member moved into and out of engagement therewith which is also coupled to a brake band. This pivoted wedge member is loaded by a spring to move outwards to allow the clutch to engage but is restrained by a trigger member under control of a latch adapted to be operated by the two control devices on the presser arm. When these are operated the clutch engages assisted by a cam acting axially. After part of a stroke, the wedge member is moved by a cam to clutch disengaging position, and the spring is restressed and the trigger member reset. As the stroke is completed, the clutch is disengaged and the brake applied to stop the presser arm in its raised position. In this arrangement, a crank-pin on the end of the shaft 8 serves to provide a final tightening of the brake band.