GB765066A - Electric circuit for tube expander and method of operation - Google Patents

Abstract

765,066. Tube expanders. AIRETOOL MANUFACTURING CO. Feb. 3, 1954, No. 3242/54. Class 83 (4). [Also in Group XXXVII] A roller type tube expander rotated by a reversible electric motor has electrical control means which, dependent upon the attainment of a predetermined load indicating that the tool has been expanded sufficiently, cut off the current to the motor and then after a slight delay cause the motor to rotate in the reverse direction, thus to withdraw the expander. A tube expander of a type described in Specification 765,065, to which reference is made, includes a tapered mandrel 11 fixed to the shaft 15 of a motor 17 and engaging radially movable rolls 9 carried in a cage 7. Rotation in one direction causes the mandrel to selffeed forward and expand the rolls and rotation in the reverse direction when the mandrel and cage are locked against relative axial movement, causes rearward movement of the expander, expanding the rest of a tube end 5 in a seat 1 as it withdraws. In operation, the on-off switch 45 and motor switch 33 being on, the latter in its lower position in Fig. 2, current flows from the supply line L1 through line 52, upper side of reversing switch 35, armature of motor 17, lower side of switch 35, ammeter 41, upper contact of relay 53, field coils 56, a lower contact of relay 53, lower contact of relay 58 and through an auto-transformer 61, rheostat 66 and coil 70 of relay 71 all in parallel, to the line 62 and thence to the line L2. As the motor comes up to speed the contact of relay 68 puts the relay coil 70 in circuit. When the rolls 9 have been expanded the load on the motor 17, and thus the current therethrough, increases until sufficient current passes through the coil 70 to close the contact of relay 71, whereupon the relay coil 63 is put into circuit to open the lower contact of relay 58 and stop the motor. Closing of contact 71 closes circuit through coil 74 of time delay relay 72 to close after a second or two the relay contact, this causes relay 53 to open upper and close lower contacts to allow current to drive motor in reverse direction. During the delay the mandrel and cage are locked against axial movement by manually turning sleeve means 21. When the cage has been withdrawn from the tube, the operator stops the motor by the switch 33. At any time the motor may be made to rotate in the reverse direction by the switch 35. Although the power supply is A.C. the relay coil 70 may be fed D.C. through rectifier means, the coil being in two parts, Fig. 3 (not shown).