Patent GB-1005889-A (GB)
Title: Work feeding and positioning apparatus
IPC: B21D28/24
Filed: 1962-05-16
Abstract: 1,005,889. Sheet metal feeds; stamping. SOC. PARISIENNE POUR L'INDUSTRIE ELECTRIQUE. May 16, 1962 [May 17, 1961], No. 18843/62. Headings B3Q and B3W. Apparatus for automatically carrying out continuous sequential machining operations with any machine tools spaced at pre-set intervals comprises a self-propelled carriage which draws the workpiece running on racks along support rollers, means for stopping the carriage at a number of predetermined working positions, means for starting the carriage after completion of the machining operation and means for returning the carriage to its starting position. The apparatus comprises a roller track 1, arranged on either side of a press 2, and provided with rollers which support an angled workpiece 3 to be punched, a bed 4 on the outlet side of the press and parallel to the bed 1 along which a driven carriage 5 travels and an arm 6 which connects a work gripper 7 to the carriage. The bed 4 is provided with rolling and guide ways 10, 11 for the carriage 5 and serrated bars 8, 9, the slots of which have a pitch of 10 mm. and into which removable stop blocks 12, 13 are fitted. The blocks have a variable dimension " L," Fig. 3 (not shown) between their stop faces and the tongues which engage the bar slots to provide a vernier-type setting. The carriage supported on wheels 14, 15, 16 is propelled by an electrically driven pneumatic-tyred wheel 17 running under the rolling way via an epicyclic reduction gear. When a brake disc 18 is gripped by electromagnetically operated jaws 19, the reduction gear 20 drives the wheel 17 with maximum torque. Reduction of the gripping force applied allows the disc to slip and the torque to be reduced, complete disengagement of the jaws allows the motor to run without driving the wheel 17. The carriage 5 carries a slideway arm 22 which supports a braking and stopping unit 23 slidable therealong. The unit comprises a rotatable shaft 24 to which the arm 6 is attached and an eccentric 25 which acts on a dovetailed slidable part 26 to which the arm 22 is connected, rotation of the arm 6 to release the work also rotates the eccentric 25 to raise the unit 23. The braking portion of the unit 23 comprises an oil reservoir 28 in which is situated as cylinder 29 integral with the unit 23 and a piston 30 secured to a part 42. When the unit is arrested by a block 12 or 13, the carriage 5 continues to advance and compresses a spring 27 which is coupled to the unit 23 and the end of the arm 22, Fig. 8 (not shown), the oil in the cylinder 29 is compressed at a predetermined rate to reduce the speed of the carriage. An adjustable calibrated valve 31 regulates the pressure within the cylinder whilst an adjustable screw 32 regulates leakage to damp the carriage movement without stopping it. A part 34 on the unit biased in a forward direction by a spring 37 carries at one end a ratchet-wheel 35 which engages the stop blocks 12 and at the other a finger 36 which actuates electric contacts 40. A pawl 38 prevents rotation of the ratchetwheel until it is tripped by an electromagnetically operated plunger 39. There are as many ratchet or exploring devices as there are tracks. The reverse speed of the carriage is twice that of the forward speed. Operation.-With the carriage against a return stop at the beginning of the bed 4, the motor is manually started and the brake applied to initially drive the carriage at full torque until working speed is reached. When a ratchetwheel engages a block, a small relative movment takes place between the unit 23 and the part 34 which effects operation of the contact 40 to reduce the driving torque applied to the carriage driving wheel 17 and the operation of the press after a predetermined time delay sufficient to allow the carriage to stop. The carriage continues its feed until the unit 23 sliding along the arm 22 completely compresses the spring 27 and the piston 30 has compressed the oil in the cylinder 29 so that it is throttled through the ports and valves 31, 32, 41 into the chamber 28, thereby braking the carriage which is held against the unit by slipping of the driving wheel clutch. At the end of a full revolution of the press drive mechanism the slide thereof trips a contact to energize the electromagnet 39 to release the ratchet-wheel 35 and the spring 27 advances the unit 23 which also energizes the brake electromagnet to restart the carriage. The carriage is stopped at the end of its travel by a limit switch which releases the driving torque at the rubber wheel 17. The clamp 7 is subsequently released manually and the arm 6 rotated through 90 degrees to release the mechanism and lift the ratchet-wheels clear of the blocks 12 and to actuate the speed change contact to return the carriage to its starting position.