Patent GB-960968-A (GB)
Title: Improvements in or relating to metal working
IPC: B21K1/46
Filed: 1962-11-21
Abstract: 960,968. Making socket head screws; extruding; forging; shearing; marking. NATIONAL MACHINERY CO. Nov. 2 1962 [Sept. 17, 1962], No. 44079/62. Headings B3A, B3H, B3P, B3Q and B3W. A workpiece is sheared from cylindrical rod stock 18, Fig. 5, by shear edges 37a, 38a spaced longitudinally of the stock whereby an oblique end 45 is formed on the workpiece and this end is then squared and upset in dies. This is stated to eliminate sharp edges on the finished workpiece. In the cold forging of socket-head screws, in a progressive header, stock 18 is supplied by feed rollers through a quill 32 at a shearing station 19, Fig. 2, and against an adjustable stop 31, Fig. 1 (not shown). A vertically reciprocating apertured cutter 34 then severs off a workpiece and moves it to a first pair of transfer fingers 23. The adjacent edges of the quill 32 and cutter 34, Fig. 5, each have a concave groove 40, Fig. 3 (not shown) to provide the spaced cutting edges 37a, 38a which cut into the stock and then cause it to rupture along line 45. The longitudinal spacing of the cutting edges is determined by the ductility and diameter of the stock. Fingers 23 transfer the workpiece to a first station 24, Fig. 7, containing an extrusion die 47 in the die breast 16. A spring-loaded die 58 is slidably mounted in a header slide 17 to surround the top of the workpiece whilst its end is squared and upset within cavity 62 by punch 64 and simultaneously its other end is extruded through die throat 49. The header slide 17, Fig. 1 (not shown), is reciprocated by a connecting rod and crankshaft. A knockout pin 51 ejects the workpiece 73 and it is transferred by the finger 23 to the next die station 26, Fig. 8, where its head is further upset in a die 78 by a punch 97 and simultaneously indented by pin 102. Vent grooves 95 are provided around die 78 for the escape of lubricating oil or air. The workpiece is ejected by a knockout pin 93 and transferred to die station 27, Fig. 10, where its head is enclosed within a die 126 and indented by a socket-forming punch 147 with an hexagonal nose 153. This operation also produces sharp corners on the underside of the head and further extrusion of the end part of the shank through die throat 134. Die 126 has a conical outer surface 124 of slightly less taper than the inner face 123 of the die holder 121, thereby producing more compression of the upper face of the die. Vent grooves 135 are provided. The lower end of punch 147 is shaped at 154 to entrap lubricating oil during piercing, Fig. 12 (not shown), this oil being supplied by a pump and nozzle. A stripping and marking die 162 is provided in a carrier 161 surrounding the punch 147 and secured to actuating rods 163. Lettering is provided on the die face, Fig. 14 (not shown), to mark the top surface of the workpiece when the rods 163 are given a blow by an anvil member 177, Fig. 13, impacted by a piston 182 fed with compressed air through port 186. During subsequent retraction of the header slide 17 and punch 147, the die 162 is biased forwardly to act as a stripper by linkage 175 actuated from the header slide connecting rod 13, Fig. 13a (not shown). A knock-out pin 141, Fig. 10, then ejects the workpiece which is transferred to a discharge station 28 where it passes out of the machine through a tube in the header slide 17, Fig. 15 (not shown), which tube contains a friction pad to prevent the workpiece dropping out. The header may be combined in a single machine with a pointer for machining the shank end of the workpiece, and a thread roller.