Patent GB-647444-A (GB)
Title: Improvement in machine tool for forming cams for steering-gear
IPC: B23F11/00
Filed: 1948-07-26
Abstract: 647,444. Milling steering-gear cams. ROSS GEAR & TOOL CO. July 26, 1948, No. 19929. Convention date, Aug. 29, 1947. [Class 83 (iii)] [Also in Group XXIII] A machine for forming helical steering-gear cams comprises means for rotatably supporting a cam-blank 27 in a frame 15, a rotary toolspindle eccentrically mounted in a drum 18 rotatable in the frame, means including a motor 108 mounted independently of the drum for driving a spindle, and means including a second motor 53 for rotating the blank and drum in timed relationship. The machine operates in a manner similar to that of Specification 643,094 to cut or grind cams of the type described in Specification 462,486, [Group XXIV]. The drum 18 is oscillated by a rack 93 and the work-piece 27 is rotated by wormgearing from the reversible hydraulic motor 53. The motor 53 also moves the rack 93 via change-gears 66, 65, a rack 56 connected to a cam slide 78, and a follower 90 which engages a cam-groove 88 and is carried on a slide 91 to which the rack 93 is attached. The inclination of the cam-groove 88 is adjustable by screws 81 and 82. Backlash preventing. - Backlash in the mechanism is taken up by a rack 101 moved to oppose the action of the rack 93 by a hydraulic piston 103. Alternatively, the piston may oscillate the drum 18 and the cam-slot 88 serve to control the movement. The spindle of the cutter 20 is rotated through belting 106 by the electric motor 108 mounted on the machine frame, the spindle and the motor mounting being connected by an adjustable link 110 so that belt tension is maintained as the drum 18 oscillates. The drum is raised and lowered, to allow removal of the work, by a bell-crank 132 actuated by a piston 133. The drum 18 is formed with a cam surface 120 to engage a follower 121 adjustably mounted on the machine-frame to control the depth of cut. In operation, electric motors 157 and 108 are started by push-buttons to rotate a hydraulic pump 156 and the cutter respectively, a hand-lever 168 is turned to advance the tailstock 26, Fig. 9, by means of a hydraulic piston, thus clamping the work-piece between centres, and a cycle start push-button is pressed. The piston 133 then lowers the drum 18 and a lever, pivotally attached thereto, actuates a switch 140 to move a valve and thereby start the hydraulic motor 53 and supply pressure to the backlash piston 103. The rack 93 carries three cams 148, 150 and 149, Fig. 10. As the rack is advanced, cam 149 releases a switch 142 which actuates a locking-bolt to prevent movement of the tail-stock 26 and at the end of the travel, when the cutting is completed, a switch 141 is actuated to reverse the motor 53 and to withdraw the piston 133 to raise the drum 18. Rearward movement of the rack 93 actuates a switch 147 to supply pressure to the tail-stock piston and, finally, the switch 142 is again actuated to stop the motor 53, withdraw the tail-stock locking bolt and allow the piston to retract the tail-stock. The switch 147, or all of the switches, may be omitted if semi-automatic or hand-operation is required. Reversing mechanism.-A slide 60, in which the rack 56 reciprocates, is adjustable vertically to allow an idler gear to be interposed in the drive to the drum 18 to permit cams of opposite hand to be produced. Headstocks ; lathe centres and carriers.-The work 27, Fig. 9, is centred in the headstock by a member 36 limited in rearward movement by a bolt and urged forwardly by a spring. The work is formed with a slot to engage a driver 42 screwed to the headstock spindle. Tail-stocks.-The locking plunger 152, Fig. 11, for the tail-stock spindle, is actuated by a solenoid 154.