Patent GB-983610-A (GB)
Title: Improvements in mechanism for setting rivets
Inventor: SIMMONS WALTER RUSSELL
IPC: B21J15/06
Filed: 1962-03-08
Abstract: 983,610. Blind riveting machines. TOWNSEND CO. March 8, 1962, No. 9000/62. Heading B3U. An attachment for a blind rivet setting tool first draws the mandrel 1 into the rivet 2 while the reaction force is applied to the head of the rivet and then transfers the reaction force to a locking ring 3 which is swaged into a recess 4 in the rivet head before the mandrel is broken off. The attachment comprises a holder casing 17 which screws into a fluid-operated reciprocating tool. Projecting from the casing 17 is a primary pressure device 21 inside which is a secondary pressure device 26 and a pulling device 22. The primary pressure device includes a nose sleeve 27 which has internal and external offset shoulders 31 and is screwed into a holder 34. At the rear end of the holder 34 is a flange 36 having radial holes 42 therein which contain locking balls 39. The flange 36 is normally locked to the holder case 17 in a position in which the balls 39 are engaged in a groove 41 by a spring-loaded lock ring 43 which is situated within the flange 36. At the forward end of the sleeve 27 is an anvil 48 mounted in a spherical seating to ensure firm engagement with the rivet head. The pulling device 22 includes a shaft 55, attached at its rear end to the piston-rod of the fluid operated tool, and urged by a spring 57 to a forward position. Secured to the forward end of the shaft is a collet 62 which has an opening 63 to allow the rivet stem to be inserted between jaws 64. The jaws are held together at their rear ends by a ring 66 positioned in grooves 67 and projecting from each jaw is a screw 68 which acts to open the jaws at the end of a rivet-setting operation. A ring 71 limits the closing position of the jaws, the hole in the ring being smaller than the stem of the mandrel, so that the insertion of the mandrel is also controlled. The jaws are urged toward the front of the collet by a spring 74. As the shaft 55 is pulled rearwardly the collet nose engages the tips of the jaws, closes them on to the mandrel stem and pulls the stem rearwards. After the rivet is set the broken-off mandrel is ejected by a spring-loaded pin 76. The secondary pressure device 26 includes a locking ring sleeve 83 which slides between the nose sleeve 27 and the collet 62 and which has a shoulder 84 co-operating with the internal shoulder 31. At the forward end of the sleeve is a tubular anvil 88 which passes through the anvil 48 and applies pressure to the locking ring 3. An internal shoulder 93 in the locking ring sleeve 83 acts on the heads of the screws 68 to open the jaws when the collet 62 is in the extreme forward position. The length of the locking ring sleeve 83 is such that in the forward position of the collet 62 the rear end of the sleeve is spaced from a flange 96 of a bushing 97. This flange has a plurality of circumferentially spaced apertures into which extend the fingers of a finger ring 101. At the forward end of the finger ring and slidable inside the locking ring sleeve is a bush 102, the length of which determines the stroke of the pulling movement because the head 59 on the shaft 55 abuts the bush 102 and moves it and the finger ring 101 and hence the ball lock ring 43 rearwards and releases the balls 39 from the groove 41, and thus unlocks the nose sleeve 27 from the holder casing 17, whereupon pressure is transmitted from the holder case 17 to the bushing 97 and the locking ring sleeve 83. In a modification, Fig. 8 (not shown), the nose sleeve is pressed through a stack of belleville washers which yield at a predetermined pressure to shift the pressure to the secondary pressure device. In a second modification, Fig. 12 (not shown), the bush 102 is secured to the shaft 55 so as to reciprocate therewith and through the ring engage a circlip in the holder and thus move the nose sleeve positively rearwards.