Patent GB-553921-A (GB)
Title: Improvements in or relating to a method of and means for making articles having a polygonal cross section
IPC: B21K1/64
Filed: 1942-01-02
Abstract: 553,921. Forging nuts and like polygonal articles. WILCOX, R. L., and WATERBURY FARREL FOUNDRY & MACHINE CO. Jan. 2, 1942, No. 66. [Class 83 (iv)] Nuts and like polygonal articles, particularly those that are in part cylindrical, are forged in stages from blanks cut from rod of circular cross section, the polygonal part being formed by a contracting die. A blank is cut at 16 from a rod 14 and transferred to a die 19 in which it is upset to form a cylindrical bolt 24, the top surface being coned by the disc 36 and conical depressions being formed on the ends by ejectors 21, 37. The forging position of the ejector 21 is determined by a spring 23 and head 22. A pin 39, behind the head 38 on the ejector 37, on connection with a backing plug 40 determines the retrograde movement of the ejector during the forging stroke. At the next stage the cylindrical part 25 of the blank is received in a die 55 mounted in a member 46 slidable vertically in a bush 42 having slots the bottoms of which are inclined at 44 correspondingly to slots 26 in the member 46. The slots 26 have transverse grooves 28 that receive ribs 106 on die sections 49 guided in the slots in the parts 42, 46 and bevelled to suit the inclined bottoms 44 of the slots for cam action. A spring 47 tends to raise the member 46 as limited by a cover plate 54 engaging surfaces 116 on the dies which are grooved at 52 for a garter spring 53. In the position shown in Fig. 1 there is clearance between the die segments and both inclined surfaces so that when the blank is driven into the die by the punch 56 and ejector 57 it engages the bevelled surfaces 107 and expands the die. As the punch continues to descend the dies are contracted radially till the surfaces 51 abut forming a closed die and swaging the bolt 24 to hexagonal form. As the punch rises the spring 47 frees the die from the blank for easy ejection by the rod 62 fitted with a spring and guide bush 63. At the next stage a flat-ended punch 66 reduces the coned upper surface of the blank to the normal chamfer the surplus metal in part filling out the corners of the polygonal part and in part increasing the depth thereof. At the next stage the blank is held by pressure on its faces from flats 88 on jaws 87 sliding in inclined T-slots 86 in a bush 80 backed up at 90. The jaws preferably leave the nuts free at the corners but the degree of freedom may be controlled by varying the backing 90 or eliminated by omitting it. The cylindrical part of the nut is held against deformation by a recess in the die 84 during holing by a punch 92. A headed sleeve 89 screwed into the bolster 83 in conjunction with a spring 91 and a groove 85 engaging lugs 112 tends to close the jaws. A pointed rod 97 passes laterally through the die and is actuated by a side rod 109 and bell crank 100 from the press head to grip the lug and prevent it returning into the nut with the punch, the upward drag of which in the nut causes the jaws to rise and release their grip. The nut is then withdrawn by the punch and stripped at 104, the slug at the same time being released to fall through the die clear of the machine. Modifications of the dies for producing the forms of nut shown in Figs. 10, 11 and 12 are described