Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
199 words
In a control system for controlling the flashing of a flash welding machine including a stationary platen for holding one of the workpieces to be welded and a movable platen for holding the other of the workpieces to be welded the improvement wherein said control system comprises an electrohydraulic valve means including means for reciprocating said movable platen, electrical coil means through which a control current flows responsive to the level of flashing voltage across said workpieces, the direction and amount of said control current flow controlling the direction and rate of flow, respectively, of hydraulic fluid through said electrohydraulic valve; and a high speed switching circuit connected to said electrical coil means for reversing said control current flow each half cycle of an applied alternating voltage through said electrical coil means to provide ''''forward'''' and ''''retract'''' hydraulic fluid pulses to move said movable platen towards or away from said stationary platen, respectively, whereby an increase in flashing voltage results in an increase in the amount of ''''forward'''' platen travel for each half cycle and a reduction in the amount of ''''forward'''' platen movement per each half cycle automatically results in an increase in the amount of ''''retract'''' movement.
Claim 2
Dependent Claim
199 words
In a control system for controlling the flashing of a flash welding machine including a stationary platen for holding one of the workpieces to be welded and a movable platen for holding the other of the workpieces to be welded the improvement wherein said control system comprises an electrohydraulic valve means including means for reciprocating said movable platen, electrical coil means through which a control current flows responsive to the level of flashing voltage across said workpieces, the direction and amount of said control current flow controlling the direction and rate of flow, respectively, of hydraulic fluid through said electrohydraulic valve; and a high speed switching circuit connected to said electrical coil means for reversing said control current flow each half cycle of an applied alternating voltage through said electrical coil means to provide ''''forward'''' and ''''retract'''' hydraulic fluid pulses to move said movable platen towards or away from said stationary platen, respectively, whereby an increase in flashing voltage results in an increase in the amount of ''''forward'''' platen travel for each half cycle and a reduction in the amount of ''''forward'''' platen movement per each half cycle automatically results in an increase in the amount of ''''retract'''' movement.
Claim 3
Dependent Claim
28 words
A control system as recited in claim 1 wherein said switching circuit includes two alternately conductive transistors for each half cycle electrically connected to said electrical coil means.
Claim 4
Dependent Claim
54 words
A control system as recited in claim 2 wherein said transistors are connected so that when either conducts, the other is nonconducting, and that conduction of one transistor causes control current flow in one direction and conduction of the other transistor causes control current flow in an opposite direction in said electrical coil means.
Claim 5
Dependent Claim
70 words
A control system as recited in claim 3 together with a pair of adjusting potentiometers connected in series with said electrical coil means, each potentiometer being bridged by a diode, which diodes are reversely connected so that one potentiometer will adjust maximum control current flow in one direction without affecting the adjustment by the other potentiometer of maximum control current flow in an opposite direction through said electrical coil means.
Claim 6
Dependent Claim
53 words
A control system as recited in claim 3 together with an indicator circuit connected to said electrical coil and with said switching circuit comprising a pair of transistors connected to a pair of indicating lamps whose response is sufficiently high as to indicate reversal of said control current up to double-line input frequency.
Claim 7
Dependent Claim
75 words
A control system as recited in claim 4 together with an input or feedback circuit from the welding dies rectifying a voltage and applying it to a schmitt trigger circuit so that the ''''forward'''' switching transistor can be made to conduct over an interval of about 150 to 0 electrical degrees through adjustment of a third potentiometer in conjunction with the setting of a fourth potentiometer through a predetermined input range of welding die voltage
Claim 8
Dependent Claim
54 words
A control system as recited in claim 6 together with a capacitor in said feedback circuit to allow the ''''forward'''' switching transistor to conduct through the full 180* interval and yeT be responsive to a reduction in die voltage if said workpieces butt sufficiently hard to reduce the weld resistance and the die voltage.