604,026. Riveting; dimpling. CHICAGO PNEUMATIC TOOL CO. Nov. 21, 1945, No. 31343. Convention date, Feb. 15. [Class 83 (iv)] A machine for dimpling and riveting in successive power strokes comprises a dimpling sleeve adapted to engage the underside of the work and act as a guide for the shank of a countersunk-head rivet while the rivet head acts as a punch to dimple the work under the influence of the upper riveting-tool and means for bringing a rivet upsetting-pin beneath the shank after its withdrawal from the dimpling sleeve so that on a second descent of the upper. tool, the rivet is set. The machine comprises a heavy yoke 21 with upper and lower jaws 22, 23, supported by a column 24 from a base 25. The upper jaw houses a plunger 28, Fig. 3, slidably mounted in spaced bushings 29, 30 and normally urged upwards by a spring 32. A casing 35 bolted to the upper jaw carries a lever 40, pivoted at 41 and resting with its nose 42 on the end of the plunger 28. A pair of rollers 49 carried by the rod of a piston 43 operating in a fluid pressure cylinder 37 are adapted to be moved forward as a wedge between the top of the lever and the underside of the casing so as to depress the lever and the plunger. The supply of pressure fluid to the cylinder 37 is under the'control of a solenoidoperated valve comprising a reciprocating valve stem 72, Fig. 8, with two spaced pairs of valve heads 69, 71 adapted to engage seats 89 and 94 in the upper position of the stem and seats 93 and 79 in the lower position. Pressure fluid is supplied to a port 98 and may be directed to the rear of the cylinder 37 by way of passage 59 or to the front by way of passage 108. A passage 106 adjacent the upper valve head 69 is connected to exhaust. The lower end of the plunger 28 receives a tool socket or holder 127 which is anchored by a rod 128 extending up through the plunger and prevented from rotating by a key 134 which passes through a slot in the upper end of the rod and into a keyway in the bushing 29. Secured to the member 127 by screws 129 is a rivet set 131, Fig. 10, surrounded by a rivet-centring sleeve 156 and a hold-down sleeve 152. Between an upper plate 138, Fig. 10, screwed to the set and a lower plate 143 retained by a split ring 144 slidable between an enlargement 142 and a rib 145 is a resilient pad 141. Between the rib 145 and a lower rib 147 is a friction ring 148 and slidably surrounding these three parts is a threaded collar 149 to which is screwed the upper end of the sleeve 152. The sleeve 156 is mounted directly on the lower end of the set and within the sleeve 152 and is urged downwards by a spring 159. The lower jaw 23 houses a sleeve 26, Fig. 6, with an upper retaining flange 27 into which is screwed an adjustable spindle sleeve 163 from the lower flange 191 of which is supported a spring casing 184. A dimpling-sleeve 162 is slidably mounted on a member 164 screwed into the upper end of the sleeve 163 and is urged upwards by three rods 178 passing through the member 164 and resting on a ring 179 on the upper end of a sleeve 181 which passes through the sleeve 163 and is supported at its lower end by a spring 185 within the casing 184. A rivet upsetting pin 161 passes through the centre of the member 164 and rests on a spindle 193 passing through the sleeve 181 and held up by a spring 197. Below the bottom 221 of the spindle is a recessed member 199 movable longitudinally by a solenoid 207 so that either the recessed or a non-recessed portion may be positioned beneath the spindle to permit or prevent its downward movement. Two switches are associated with the lower jaw mechanism. One of these, 225, is adapted to break contact between members 235 and 236 on the descent of the sleeve 181, which acts on member 235 through a collar 182, depending bolt 240 and plunger 237. In the other switch, movement of the member 199 to prevent downward movement of the spindle 193 moves an arm 226 to the right as seen in Fig. 6, allowing contact member 231 to move from contact 232 to contact 233. Another switch is housed in a casing 247 on the upper jaw 22. A U-shaped deflection plate bolted to the lower jaw at 243 extends into this casing with its end 246 resting on one end of a bell-crank lever 261, Fig. 4, the other end of which is adapted to depress a plunger 259 and so move a contact member 258 away from a contact 260 and on to a contact 257 when the yoke has been subjected to a predetermined amount of strain. In operation, the two plates to be riveted, with the rivet already in position in the holes are placed on the dimpling-sleeve 162 so that the protruding rivet shank extends into the sleeve. The pedal 254 is depressed to connect the starting switch and compressed air is supplied to the cylinder 37 to depress the plunger 28. The depressed portion of the member 199 is below the spindle 193 which moves downwards with the work and rivet, the shank of which enters the bore of the member 164 and under the pressure of the set 131, the plates are dimpled as shown in Fig. 10. During the descent of the sleeve 181, the switch 225 is operated and finally the deflection switch in the casing 247 is actuated to stop the supply of compressed air to the rear of the cylinder 37 and the plunger begins to move upwardly. The member 199 is moved to the right by the solenoid 207 and the plunger again depressed to head the rivet between the set 131 and the pin 161, the actuation of the switch 225 serving to stop the operation when the rivet has been headed to a predetermined height. The parts of the machine then return to their original positions ready for a fresh cycle of dimpling and riveting operations.