Patent GB-756762-A (GB)
Title: Improvements in or relating to an apparatus for forming hollow metal rivets and method thereof
Inventor: FRIEDMAN JOHN HENRY
IPC: B21K1/58
Filed: 1954-03-03
Abstract: 756,762. Forging hollow rivets and the like. NATIONAL MACHINERY CO. March 3,1954, No. 6225/54. Class 83 (4). Hollow rivets are made by inserting a blank B1, Fig. 5, in a sliding die D1 containing a punch P1, pressing the die and the blank towards the punch so as to extrude a portion of the blank over the punch, inserting the pierced blank in a second die D2 and upsetting a head thereon. The upsetting machine is similar to that described in Specification 639,054 having feed rollers for moving stock bar 31 through a quill Q against a gauge pin 28 in a shearing block 23 which is then moved across the face of the die breast 17 to shear off a blank B1 and position it in alignment with the die D1. A tool T1 on the heading slide 12, Fig. 1 (not shown), which is operated by a crank, then strikes the gauge pin 28 which pushes the blank B1, Fig. 5, into the die D1. On the next stroke of the heading tool the tool T1 has been moved automatically out of position, as described in Specification 639,054, and replaced by another tool T3, Fig. 2, which presses the blank B1 and the sliding die D1 over the punch P1 which is held stationary by a rigid abutment 42. A stripping sleeve 51 is then moved to the right by a camoperated arm 38, through sleeves 43, 53 to eject the blank from the die. The punch P1 initially moves with the blank until it is'stopped by the engagement of pin 54 with the sliding die D1 which is spring-biased to the right. The ejected blank is gripped by transfer fingers 24, Fig. 1A (not shown), which are of either of the alternative kinds described in the above-mentioned Specification, and moved into alignment with the second die D2. The tools on the header slide are again changed and a spring-loaded plunger 72 in a preliminary heading tool T2, Fig. 5, presses the blank into a hardened die plate 66 against a stationary punch P2 having a tapered nose 69 which expands the hollow portion of the blank against the conical wall 67 of the die cavity and thus increases the friction between the die and the blank thereby restricting further penetration thereof. The tool T2 has a cavity 71 which forms a preliminary head on the blank. During the next working stroke of the header slide the tool T2 has been replaced by a final heading tool T4, Fig. 2, which completes the head on the blank B4. The punch P2 is then moved to the right through a bar 61 by a cam-operated arm 39 to eject the blank and during this ejection the shank is drawn to cylindrical form and is elongated. In another embodiment, Fig. 10 (not shown), the die D2 is slidable axially to the left during the heading operation and abuts an adjustable wedge which together with adjustment means for the punch P2 permits changes in the depth of piercing of the blank. In a modified form of ejector for the die D1, Fig. 12, the blank B2 is pushed completely out of the die by the punch P1, and a finger 113 carried by a cam-operated arm 111 is moved over the punch between the blank and the die breast. During the subsequent retraction of the punch the finger 113 prevents any retraction of the blank and thus withdraws it from the punch.