Patent GB-1290322-A (GB)
IPC: B21F35/02
Filed: 1968-09-25
Abstract: 1290322 Bending loops in coil springs BRITISH UNITED SHOE MACHINERY CO Ltd 16 Dec 1969 [25 Sept 1968 17 Sept 1969] 45461/68 and 45756/69 Heading B3E A method of forming a loop at an end portion of a coil spring comprises supporting the spring so that an end portion projects, moving a first portion of a first tool transversely of the support means to separate one or more coils of the projecting portion to provide a loop, next moving a second portion of the first tool transversely of the support means to engage the loop and bend it further, said second portion thereafter maintaining the loop in position, and then moving the second tool towards said second portion, the wire of the spring being engaged between the second tool and second portion of the first tool to impart a permanent set. A machine for carrying out the method comprises a grooved base-plate 10 accommodating opposed slidable tool blocks 14 and 16 lockable in any desired position by bolts 19 and adjustable by screw members 28 and 50 (Fig. 1) The blocks are manually operated by pivoted levers 32 and 33 (Fig. 2). A groove 58 extends across the front face of the block 14 and houses a fixed anvil plate 60 and a slidable lifting tool 66 which provides the first portion of the first tool, the anvil plate 60 providing the second portion. A hammer 82 provides the second tool and is mounted on the block 16. A boss 92 carries a tubular holder 106 for the spring which is inserted in a bore 107 and clamped in position after being located by a spring-loaded adjustable member 116 (Fig. 3) held in its forward position by a spring-loaded latch 124 releasable by a cam bar 138. In operation the locating member is first moved to its forward position where it is retained by the latch 124. A coil spring is ininserted in the bore 107 until its near end engages the head 118 of the locating member and the spring is rotated until the wire end engages a stop 144 on the head so that part of the coil projects from the supports. The handle is rotated by the operator to move block 16 towards its outermost position and a spring- loaded bar 146 pulls the lifting tool 66'and the block 14 remains stationary by means of a spring 30. As the block 16 near its outermost position the cam bar releases the lever 124 and allows the locating member to move rearwardly clear of the machine tools. The lifting tool forms a loop 162 (Fig. 4b, not shown). The operator then moves the handle 36 so that the block 14 near its innermost position and the anvil 60 bends the loop. Finally the operator moves the handle 37 to move the block 16 towards its innermost position to move the lifting tool and bar 146 to the right and allow the hammer 82 to engage the wire where the loop joins the coil to press the wire against the anvil to give it a permanent set. In another embodiment the machine comprises a base-plate 182 (Fig. 7) supporting tool assemblies 186, 188. The assemblies include opposed compressed air motors 193, 195 which reciprocate racks 226, 232 integral with pistons 200 and 228. (Fig. 8). The racks co-operate with pinions 242, 240 and the pinion 242 also engages another rack 244 and the pinion 240 an adjacents rack 248 parallel to the rack 244. A front tool holder 256 is secured to the rack 244 and a rear tool holder 258 to the rack 248. The tool holders are adjustable by screw members (270 for tool holder 256). A coil opening tool is secured to the holder 256 and an anvil tool to the holder 258. A hammer tool 338 is mounted on a tool holder 334 in the left hand assembly the cylinder block 306 of which is pivotally mounted on the baseplate 182 and lockable in any desired position. A spring supporting block 360 has a rotatable holder for correctly orientating the spring. A guage 382 having a pivoted bell-crank lever 390, 392 actuated by an air motor 396 ensures that a rod 416 within the spring holder is in axial alignment with an adjustable locating face 510. The opening tool 298 and the anvil tool 512 are similar to the tools 60 and 66 of the first embodiment and the operation is described with reference to Figs. 9 to 12 (not shown). In a further embodiment a loop 604 (Fig. 14) is separated by the opening tool 298 and then bent further by the tool 512 over the tool 600. On removal of the tools the loop 604 springs back to the desired position.