Patent GB-894541-A (GB)
Title: Improvements in pulling-in dogs for machines for drawing wire and other elongated material
Inventor: CLAYTON PHILIP ARMSTRONG
IPC: B21C1/14
Filed: 1959-11-03
Abstract: 894,541. Drawing. MARSHALL RICHARDS MACHINE CO. Ltd. Nov. 2, 1960 [Nov. 3, 1959], No. 37229/59. Class 83 (4). A pulling-in dog for a wiredrawing machine comprises an arm pivotally mounted on the drawing block with its pivoting axis substantially parallel to the axis of rotation of the drawing block, a gripper means mounted on said arm for pivoting movement relative to the arm about an axis spaced from and substantially parallel to the pivoting axis of the arm, means for locking the arm sc that the gripper means is located adjacent to the peripheral surface of the drawing block, and power - operated means for moving the arm into a position in which the gripper means is spaced from the peripheral surface of the drawing block. The apparatus comprises an arm 1 pivoted at one end on a shaft 2 secured to the upper surface of a drawing block 4. The other end of the arm has mounted therein bearings 7 which support a spindle 8 which in turn supports a gripper means 9. The gripper comprises converging guideways 14, gripping jaws 15 and a double-acting fluid cylinder assembly which includes a cylinder 17, a piston 19 and a pistonrod 20. The rod 20 is connected to the gripping jaws by a cross-pin 22. A supply of pressure fluid is permanently connected to the space 17 on the left of the piston (Fig. 3) via the duct 24 and a flexible pipe 27. The arm is locked in a position adjacent the drawing block periphery by a latch mechanism which comprises a locking plate 36 mounted on the top surface of the drawing block and a spring- loaded bolt 32 mounted on the arm. A boss 37 on the bolt receives a pin which connects the bolt to an arm 39, the other end of which is connected to a boss 42 on a hub 40. Also projecting from the hub is a lug 43 which is in line with a double-acting fluid cylinder assembly 45. The piston 44 is normally held in the retracted position by a supply of pressure fluid through a port 46. When fluid at the same pressure is supplied to a port 47 the piston moves out, since the effective piston area presented to the port 47 is greater than that presented to the port 46, and first withdraws the bolt 32 and then causes rotation of the arm 1 about the shaft 2. As the gripper means 9 swings clear of the recess 31 a tension spring 48 connected between an attachment 49 on the arm and an attachment 50 on the gripper causes it to rotate into alignment with the arm. The arm is bolted by an adjustable stop 51 when the gripper is aligned with a die 53. The wire to be drawn is passed through the die and into the gripper 9 and pressure fluid is applied to the right-hand side of the piston 19 via the pipe 29, which forces the jaws 15 along the guideways 14 to grip the wire. The fluid supply to the cylinder 45 via the port 47 is then released and the piston 44 retracts. When the drawing block is set in rotation the tension in the wire swings the arm 1 to return the gripper 9 to the recess 31. It is unnecessary to maintain the supply of pressure fluid to the right-hand side of the piston 19 since the tension in the wire prevents the jaws 15 releasing. When drawing is completed and the tension releases the pressure fluid supplied to the left-hand side of the piston 19 opens the jaws and the wire end drops through a slot 54 in the gripper. For heavy drawing the construction should be modified so that the gripping means is disposed between two parallel arms.