Patent GB-600716-A (GB)
Title: Improved method of and apparatus for making nut blanks
IPC: B21K1/70
Filed: 1944-09-04
Abstract: 600,716. Making and forging nuts. WATERBURY FARREL FOUNDRY & MACHINE CO. Sept. 4, 1944, No. 16846. Convention date, April 22. [Classes 83 (ii) and 83 (iv)] A method of making a nut blank comprises cutting a blank from solid bar stock, forming a plurality of axial ribs thereon and then ' flowing the metal of the blank axially to form upstanding petals at a transverse face of the blank between the positives of the ribs. The work is carried out in a machine comprising a holder 11, Fig. 1, for a number of forming dies and a reciprocable gate 14 carrying punches adapted to co-operate with the dies. The blanks are carried from one work station to another by transfer mechanism of known type. At the first station a blank is cut from a rod 19, by a tool 20 and at the second station this blank is squared and formed at its ends with conical depressions within a die 22 by means of a punch 30 co-operating with the conical end of a knockout pin 24. At the third station the blank is centred between the conical ends of a knock-out pin 44 within a die 42 and of a pin 36 urged outwardly from a punch 34 by a spring 37. On the advance of the punch, the blank is moved into the die opening 46 which is of larger diameter, and wherein it is reduced in thickness and expanded laterally, the outer surface being formed with six axially extending ribs and the upper surface being formed with a washer face 49 and a fillet 48, Fig. 7. At the fourth station three dies 71, 72 and 73, Fig. 9, hexagonal in shape and of decreasing diameter are mounted in holders 74, 75 and 76 within a sleeve 69 and are retained by a plate 66 having an opening 67 with grooves or recesses 70 designed to register with the ribs on the blank. These dies are supplied with lubricant through passages 80 and 81 and through grooves 82 extending radially along the rear faces of the holders 74 and 75. A hexagonal punch 60 pushes the blank through the plate opening 67 and then successively through the three dies which give the blank a hexagonal shape, the corners of the hexagon corresponding to the positions of the ribs of the blank, reduce its diameter and increase its depth and also cause metal to flow axially to form a recess 91 surrounded by a hexagonal wall having rounded petals 92 as shown in Fig. 5b. This blank is ejected by a pin 83 and passed to the fifth and last station where it is pierced by a punch 94. The piercing die 95 is surrounded by six T-head retaining dies 96 with tapered surfaces engaging a taper within a sleeve 97. As the punch advances, the dies move slightly rearwardly with a consequent compression of the dies 96 so as to prevent any lateral flow or distortion of the blank. When the punch retires, it withdraws the blank from the die and carries it rearwardly until it is stripped off by a bush 111 carried by an arm 110 slidable rearwardly in a fixed part of the machine within the limit allowed by a stop 108. The nut is later completed by tapping the blank, inserting a fibre or other washer in the recess 91 and bending over the petals 92 to form retaining lugs. U.S.A. Specification 1,977,163 is referred to.