Sequence Timer for Electric Resistance Welders

1,197,197. Control systems for resistance welders. INSTITUT ELEKTROSVARKI IM. AKADEMIKA E. O. PATONA. 19 Dec., 1967, No. 57497/67. Heading H2H. A sequence timer for an electric resistance welder has a decatron pulse counter connected to a decatron sequence switch, the latter having an amplifier connected to its input, and AND circuits connected through an OR circuit to the output. To start the counter and ensure automatic operation without resetting the sequence switch to zero the output of a start cathode and a cathode corresponding to the last operation of a sequence switch are connected through a change-over contact of a starting relay to the input of the amplifier to a delay circuit, the change over switch being connectible to the sequence switch for connecting alternatively at least some of the cathodes of the sequence switch singly or in parallel to a cathode resistor and the inputs to the AND circuits depending on the required duration of the operations. On initially connecting the circuit to a supply a discharge occurs in decatron sequence switch 17 at the cathode corresponding to a " time interval " operation, i.e. that connected to a capacitor 26 which is charged through diode 29 and resistor 30, the potential across the latter preventing energization of a relay 32 through amplifiers 22, 24 and diode 31. A pulse shaper 9 is also blocked through resistors 33, 35 amplifier 21 and diode 34 and a capacitor 37 is charged through a selector switch 38. The potential across resistor 30 also establishes a discharge at cathode I through amplifier 22 resistor 39 contact 12 delay element 25 and amplifier 20. When a start button switched 41 is closed relay 11 operates connecting amplifier 10 to amplifier 20 transferring the discharge to cathode II which corresponds to the commencement of the pressure operation. The disappearance of an input to amplifier 10 energizes an E.P. valve through contacts 43 of relay 32 and causes discharge of capacitor 37 through diode 44 and resistor 35, the pressure period being determined by the discharge of capacitor 37, after which the pulse shaper 9 is unblocked and decatron 2 counts transferring every tenth count through amplifier 19 to decatron 3. When the count is equal to that set by switches 4, 5 a positive pulse appears at one of diodes 46 which is delayed through element 25 and supplied to amplifier 20 transferring the discharge in decatron 17 to cathode III corresponding to the welding operation and simultaneously decat