Patent GB-538763-A (GB)
Title: Improvements in or relating to safety devices for power presses
IPC: F16P3/24
Filed: 1940-02-10
Abstract: 538,763. Machinery safety devices. BRITISH UNITED SHOE MACHINERY CO., Ltd., KEALL, F. B., RICKS, F., and FRAMPTON, S. E. (United Shoe Machinery Corporation, in part). Feb. 10, 1940, Nos. 2607 and 13884. Addition to 518,822. [Class 80 (iv)] The parent Specification describes a safety device for power presses of the kind comprising a work-supporting bed, a presser arm carried by an upwardly extending post, the presser arm being capable of swinging movement about the axis of the post over the bed, a tool placed by the operator on a workpiece, power means to move the presser arm towards the bed and an operator controlled starting member for causing engagement of said power means, the starting member being mounted to partake of swinging movement of the arm, and a control member which must be actuated as well as the starting member to effect engagement of the power means, both hands of the operator being necessary to start the press. According to the invention, the control member actuates a latching device co-operating with a part that during operations of the press remains stationary and relatively to which the presser arm moves in operating, the arrangement being such that adjustment of the presser arm in relation to the work-supporting bed may be effected without affecting starting means of the press. In Fig. 1, an arm 10 is secured to a vertical post 12 mounted for swinging movement about a vertical axis and for vertical reciprocation in the fixed frame 8, a bed 14 being provided for the material to be acted upon by a cutter. Upon tripping the clutch the main shaft makes one revolution and stops, the arm having then been depressed and raised again to its original position. A yoke 16 secured to the arm by bolts 18, has pivot studs 22 for a U-shaped handle 26. Rotatable with one of the studs is an arm 28 connected through a link 30, bell-crank lever 32, 34 and link 38 to the lower arm 62 of a lever 62, 64 pivoted on a stud 66 on a casting 48 which has an annular projection 46 received between annular projections 42 of a spring-loaded clutchtripping lever 40 pivoted at 39. Secured to the casting 48 is a rod 50 the bifurcated end 51 of which embraces a knob 52 fixed to a rod 54 slidable in the arm 10. The upper arm 64 of the lever 62 carries a C-shaped latching member 70 partly surrounding an arcuate rail 78 fixed to the frame. A spring-pressed plunger 76 tends to push the handle 26 downwardly, the short arm 74 of the part 70 lying behind the rail 78. Lifting the handle 26 will move the lug 72 of the part 70 clear of the rail and allow movement of knob 52 downwardly to trip the clutch ; thus both hands of the operator are necessary to start the machine and the directions of movement of the knob 52 and handle 26 are directly opposite one another. If the operator attempts to foil the purpose of the safety device by fixing the handle 26 in a raised position, the rail 78 prevents return of the knob 52 to its original position which return is essential for further tripping of the clutch. In another form Figs. 1, 2, an arm 114 is again mounted for swinging and vertical movement on a post 112 and carries a knob 118 embraced by one end of a rod 122 the other end of which is connected through a casting 130 with extension 132 to a lever 124 connected to a clutch-tripping rod 126. To ensure that both hands of the operator are employed in starting, a latch 142 is pivoted to the casting 130 and engages a ledge 146 on a U-shaped rail 148 mounted on a pivot pin 138 and thus prevents clockwise swinging of lever 124 until rendered inoperative by a control 150 requiring the use of the other hand. The latch has a tail portion 156 engaged by a spring 158 resting on a casting 130. Co-operating with the latch is a dog 160 one end of which rests on the ledge the other end being mounted on a pivot 162 carried by one arm 164 of a bell-crank lever 166 mounted on pin 144. The dog 160 has a recess 168 to receive a pin 170 on latch 142, the arrangement being such that upon clockwise rotation of lever 166 the recess rear wall catches pin 170 and releases latch 142 from ledge 146. Lever 166 is actuated from control 150 through a universal joint 202, sleeve 200, rod 206 and a shaft 172 rotatably mounted in casting 130. This shaft has arms 174 arranged to engage stud portions 176 carried by tail portions 178, 179 of lever 166. The casting 130 has a transverse portion 180 carrying two spring-loaded plungers 182 each of which engages one of the arms 174. The control device 150 comprises an axially movable shaft 188 with a disc 192 at each end. By pressing on either of these discs, the lever 166 is moved clock-wise to disengage the latch 142 from the ledge 146 after which the knob 118 is depressed to trip the clutch ; in this case, the directions of movement of the knob 118 and the shaft 188 are at right-angles to one another. The rail 148 corresponds to the rail 78 in the form described above. Actuation of the latch-actuating parts is unaffected by adjustment of the presser arm and post. Specification 22023/05, [Class 31], also is referred to.