Patent GB-680542-A (GB)
Title: Apparatus for punching holes in continuously advancing material
IPC: B26F1/06
Filed: 1949-07-12
Abstract: 680,542. Punching-machines. DUNLOP RUBBER CO., Ltd., SCOBIE, A. J., and ROWE, R. L. June 7, 1950. [July 12, 1949] No. 18357/49. Class 31 (ii). Apparatus for punching holes in strip or tubing made of rubber or other material while it is continuously advancing comprises a tubular punch pivotally mounted to swing in one plane about the end remote from the cutting edge, means to move the punch during the cutting stroke, means to move the cutting end of the punch from the line of stroke during the cutting stroke whereby the cutting edge contacts the advancing material when the punch is inclined to the line of stroke, means to permit the cutting end of the punch to travel with the material during the remainder of the stroke of the punch, and means to restore the punch to its original position in readiness for another cutting stroke. The apparatus shown, which is for cutting valve holes in rubber tubing 3 carried on a conveyer 2, comprises a base 7 having front and rear cover plates 8, 9 secured thereto, each cover plate having a guide slot 13, Fig. 1, the sides 14, 15 of which are of different inclination and, on its inner side, a cavity 16 having its sides parallel to the sides of the guide slot but extending upwardly therefrom. The punch is pivotally supported at its upper end by means of two pins 23 projecting radially therefrom and each carrying a roller 25 located in one of the cavities 16. Two further pins 26 which project radially from the punch extend through the guide slots 13 and carry rollers 27 which are located in the cavities 16. The punch is actuated by means of cams 33 on a shaft 32 which is driven from a shaft 85 by means of a chain and sprocket wheels. The punch also comprises a spring-influenced ejector plunger 28 which is actuated by means of a cam 34 on the shaft 32. The disc punched from the tubing is removed by means of a semi-circular carrier plate 42 carried by a shaft 38 rotatable from the shaft 32 and having an abutment, and a circular projector plate 44 having a projecting finger 45, the plates 42, 44 being connected by means of a spring 47. The abutment and finger 45 co-operate with a projection 51 on a spring-influenced trigger 48. Slidably mounted on the base 7 are two blocks 54 each containing an electrically-heated element 55 and having a semi-circular slot 56 in its inner face so as to form a cylindrical aperture for the reception of the punch when the two blocks are moved towards each other. Pins 57 project from each side of an extension 58 of each block and extend through slotted holes 59 in the cover plates, tension springs 62 being secured to the ends of the pins. Two pairs of bell-crank levers 63 are located adjacent the front and rear cover plates, the lower arm 65 of each lever engaging one of the pins 57 and the upper arm 66 having a cut-out portion 67 which is in contact with one of the rollers 25. Light tension springs 68 connect the pins 26 to the spindles 64 of the bell-crank levers on the side of the centre line of the cover plates in which the sides 15 of the slots 13 are disposed. Attached to the base 7 is an upper electromagnet 69 comprising coils 70 and poles 71, the latter being adjustable with respect to the base 7 by means of screws 73. The poles have secured thereto bushes 78, 79 for guide bars 80, 81 and a lead screw 82, the ends of the guide bars being secured to support plates 6 extending upwardly from a table 1. A further guide bar 88 is secured to the support plates and the table, and a second lead screw 89 is mounted between the support plates. The lead screws are connected together and serve to adjust the position of the punch in a transverse direction. The guide bar 88 and lead screw 89 support a lower electromagnet 90. The upper and lower magnets are arranged so that their like poles face each other and between the poles a bearing member 91 is placed inside the tubing 3, the bearing member having an insert 93 of hard rubber and curved portions 94 or rollers. Means may be provided for rotating the cutting portion 18 of the punch during the punching operation. The apparatus is located near the end of the conveyer adjacent the water bath into which the tubing issues from the extruding machine. Operation. The cam shaft 32 is rotated to force the punch downwards. At the same time, the rollers 25 are forced downwards to depress the arms 66 of the bell-crank levers forcing the arms 65 and blocks 54 outwards. As the punch is forced downwards, the pins 26 follow the sides 15 of the guide slots 13 and the punch pivots about the pins 23 so that its cutting edge 19 is pulled in the direction opposite to that in which the tubing 3 is moving. The pins 26 follow the contour of the sides 15 so that the cutting edge of the punch changes direction and while still on its downward path commences to follow the tubing. Just before reaching its dead centre position, the cutting edge contacts the tubing and moves forward with it. On the punch reaching its dead centre position, the cams 33 reach their bottom dead centre position and apply the maximum pressure to the punch so that its cutting edge cuts a hole in the tubing. The pins 26 then contact the sides 14 of the guide slots and the pressure is removed from the punch. At the same time, pressure is removed from the arms 66 of the bell-crank levers and the springs 62 pull the blocks 54 and arms 65 towards each other thus moving the arms 66 upwardly, taking with them the pins 23 supporting the punch, and the pins 26 return to the top of the slots 13. With the blocks 54 in contact with the punch, the latter is heated by means of the elements 55. When the punch has cut a hole in the tubing, it bears against the insert 93 of the bearing member. The pressure of the punch acting through the tubing moves the bearing member forward with the tubing until the hole has been punched and the punch withdrawn. When the bearing pressure is removed, the bearing member is attracted back to its central position between the magnets. The carrier plate 42 is then passed beneath the punch to receive the disc of waste material punched from the tubing and ejected by the plunger 28, and the plate 44 is moved over the plate 42 to remove the disc therefrom. Automatic means, e.g. a trip mechanism, may be provided to cut the supply of electric current from the magnets when the punch contacts the tubing. When the punching operation is completed, the magnets are automatically energized again. The magnets may be arranged at each side of the tubing. If the bearing member is not required to move appreciably during the punching operation, the electromagnets may be replaced by permanent magnets. When the invention is used for cutting holes in a continuous strip of rubber or other material, the magnets are omitted and a fixed bearing member substituted for the movable bearing member. Specification 680,541 is referred to.