Patent GB-920381-A (GB)
Title: Improvements in indexing fixtures for machine tools
IPC: B23Q1/68
Filed: 1961-03-21
Abstract: 920,381. Machine tool details. ERICKSON TOOL CO. March 21, 1961 [Oct. 21, 1960], No. 10326/61. Class 83 (3). [Also in Group XXIV] In a machine tool a work indexing fixture is moved towards and away from the tool and is indexed automatically in the retracted position. The fixture comprises a housing 1 having a work carrying spindle 6 rotatably mounted therein, a ratchet wheel 16 non rotatably carried by the spindle and a rotatable member 15, having a toothed segment 18, and a lug 19. A bolt 21 is screwed into lug 19 and carries a pawl 20 urged into engagement with teeth 24 of wheel 16, by a torsion spring 25, and a cam 26 having a cam face 27, is secured to member 15. A spring- urged plunger 28 engages teeth 24 on wheel 16, and is moved radially outwardly to disengage the teeth by face 27 when member 15 is rotated counter clockwise, such rotation being limited by engagements of lug 19 with a pin 42 inserted in one of the openings 43. A spring-loaded holding pawl 38 for wheel 16 is carried by an adjustable block 39. Member 15 is oscillated in opposite directions by a piston rod 49 having annular grooves 50 engaging toothed segment 18; rod 49 being reciprocated by fluid-operated pistons 47, 48, secured to the rod. A further piston 51 is connected to a member 76 carried by spindle 6, by a link 54 and takes up lost motion when indexing occurs. In operation with the fixture mounted on the machine table 80 which is retracted, Fig. 7, a workpiece is mounted on spindle 6. In this position switch 101 is open and switch 93 is closed, contactor 105 is closed and solenoid 94 is energized to allow a valve 67 to supply air to cylinder 45, thus moving piston rod 49 to the right to rotate member 15 counter clockwise until lug 19 engages pin 42. Pawl 20 passes over teeth 24 on wheel 16, which is held stationary by pawl 38, and piston 52 is moved to the left. Plunger 28 is forced from teeth 24 by face 27, on member 15, and the indexing mechanism is cocked. Lug 19 as it engages pin 42 moves a plate 86 having a screw 89 in a counter clockwise direction to close a switch 90 which allows valve 67 to exhaust air from cylinder 45 and supplies air to cylinder 46. Piston rod 49 moves to the left and rotates members 15, 16 in a clockwise direction, to index spindle 6, pawl 20 being held in a tooth 24 by a lug 75 on member 76, and piston 52 providing a cushioning action. Plunger 28 moves inwardly to lock wheel 16 and switch 91 is closed, switch 101 is closed and a circuit including solenoid 99 of a valve 82, advance switch 97 and contactor 102, is closed and air is supplied to cylinder 81 to move the table 80 to the right. As the table approaches its working position a cam 106 closes a switch 107, to establish through a valve 84, a restriction of the flow of air to cylinder 81, thus reducing the table feed rate. Finally, a retract switch 98 is actuated by a lug 96 on piston 85, a solenoid 100 in valve 82 is excited and air is supplied to the opposite end of cylinder 81 to retract table 80, and simultaneously contactor 105 is closed, ready for successive cocking and indexing movements of the fixture after the table has been retracted. Specification 676,901 and U.S.A. Specification 2,883,886 are referred to.