GB700628A - Improvements in or relating to an apparatus and method of making stranded cable - Google Patents

Abstract

700,628. Control of motors. JOHNSON STEEL & WIRE CO., Inc. Jan. 19, 1951, No. 1483/51. Class 38(3),[Also in Group XXV] A machine for making steel wire rope, (see Group XXV), is provided with means to stop the machine in the event of breakage of a wire or strand, or when the tension in a wire component of a strand exceeds a predetermined value. Wires W from bobbins 4 are twisted into strands S which are drawn through closing dies 13 and into a cable laying die D by a capstan unit B. The cable is further twisted in a flyer C and wound upon a storage spool E. The machine is driven by an electric motor M. The wires and strands are normally insulated from the machine by providing insulated bearing mountings and pulleys, e.g. 72a, 72b, 12a and 3a, Fig. 13. The wire is connected to a source of potential, 69, and a broken wire or strand would complete the circuit between 69 and 70. Wire being drawn from a bobbin 4 passes over pulleys 8 and 9, the latter mounted on a pivoted arm 59 so that the tension in the wire opposes the. pull of a spring 53. When the tension reaches a predetermined value the rotation of the arm 59 is sufficient to close a contact 66 which again completes the circuit between 69 and 70. The filament voltage for a Thyratron tube 68 is supplied from a transformer 104 upon closure of a switch 105 leading to an A.C. supply. A time delay relay 106 prevents a main contactor 107 from being closed until the filament of tube 68 has had sufficient time to heat after which the contact 108 is closed and the machine may be started provided there is no circuit between 69 and 70. Closure of a push button 109, energizes the coil 110 of contactor 107 and so closes contacts 111 and 112. The contactor 107 locks in electrically through contact 112 and voltage is applied to the motor M and magnetic brake 113 so starting the motor. A.C. is now supplied to a transformer 114, from the output of which a copper oxide or selenium type bridge rectifier 115 gives a D.C. voltage between the points 116 and 117. A filter condenser 118 is provided across 116 and 117 and this voltage is impressed across a voltage divider consisting of resistors 119 and 120. This gives a negative grid bias voltage at 121 with respect to the cathode of tube 68 and prevents the tube from conducting. Should a connection between 69 and 70 be established the grid is brought to earth potential current flowing through the tube opens contact 122 and breaks the lock-in circuit of magnetic contactor 107 and 'causes it to open so de-energizing the motor and applying the brake 113. Opening the contactor 107 isolates the transformer 114 so extinguishing the tube which allows contact 122 to be closed, and by holding down the jog button 125 by passing trip relay 122, and with 69 and 70 again disconnected the machine may be started by the button 109, the trip relay contact 122 reopening immediately upon application of plate voltage to tube 68, the contact 122 remaining open as long as the control grid is at zero potential. The motor M may be replaced by several separate motors each driving a separate part of the machinery, each functioning through the main contactor 107.