Welding control system

Claim 2

In a resistance welding system for selectively connecting a load having a power factor to a source of alternating voltage during each of at least certain of the half-cycles of the alternating voltage for each weld, a method of controlling the welding system comprising the steps of sensing the power factor of the load, controlling the connection of the load to the source by generating a curve having a selectably variable slope characteristic, initiating the generation of the preselectable slope timing curve for selecting the percent heat fed to the load, and disabling the power factor sensing system during a selected portion of the first half-cycle of the weld, connecting the load to the source during each of a succession of half-cycles of the source and sensing the power factor of the load during each of a plurality of the half-cycles subsequent to the first half-cycle during a single weld.

Claim 3

A method according to claim 1 further including producing a signal indicative of the power factor of the load, and controlling the percent heat application in response to the signal.

Claim 4

A method according to claim 2 wherein the signal is indicative of the termination of the flow of current through the load.

Claim 5

A method according to claim 3 wherein the signal is indicative of the voltage across the device.

Claim 6

A method according to claim 4 further including selectively actuating the controllable rectifier device a selectable interval after initiation of timing, and controlling the initiation of timing in response to the signal.

Claim 7

A method according to claim 5 wHerein said method includes simulating a substantially purely inductive load for the first half-cycle thus simulating a substantially 90* power factor when the power factor sensing is disabled.

Claim 8

A method according to claim 6 further including actuating the devices by applying a pulse of electrical energy thereto, and disabling the transmission of the pulse until the preselected signal is received.

Claim 9

A method according to claim 7 further including delaying actuation of the devices for a selectable period following the initiation of timing.

Claim 10

A method according to claim 1 further including comparing the magnitude of the timing curve to a fixed level and generating an output signal when said timing curve bears a preselected relationship to said fixed level.

Claim 11

A resistance welding control system for selectively connecting a load having a power factor to a source of alternating voltage during each of at least certain of the half-cycles of the alternating voltage for each weld, said system including a sensing means for sensing the power factor of the load, heat control means including a timing curve generating means controlled by the sensing means for controlling the connection of the load to the source, said curve generating means generating a curve having a preselectable constant characteristic portion and a portion having a selectably variable slope characteristic, said sensing means initiating the generation of the preselectable characteristic timing portion by the generating means, means for selecting the variable slope and, thus, selecting the percent heat fed to the load, and means for disabling the power factor sensing means during the first half-cycle of the weld.

Claim 12

A resistance welding control system for selectively connecting a load having a power factor to a source of alternating voltage during each of at least certain of the half-cycles of the alternating voltage for each weld, said system including a sensing means for sensing the power factor of the load, heat control means including a timing curve generating means controlled by the sensing means for controlling the connection of the load to the source, said curve generating means generating a curve having a preselectable constant characteristic portion and a portion having a selectably variable slope characteristic, said sensing means initiating the generation of the preselectable characteristic timing portion by the generating means, means for selecting the variable slope and, thus, selecting the percent heat fed to the load, and means for disabling the power factor sensing means during the first half-cycle of the weld.

Claim 13

A resistance welding control system according to claim 10 wherein the load is connected to the source during each of a succession of half-cycles of the source and in which the sensing means senses the power factor of the load during each of a plurality of the half-cycles during a single weld.

Claim 14

A resistance welding control system according to claim 10 wherein the sensing means produces a signal indicative of the power factor of the load, and in which the heat control means is responsive to the signal.

Claim 15

A resistance welding control system according to claim 12 wherein the load is connected to the source during each of a succession of the half-cycles of the source and in which the sensing means produces a signal indicative of the power factor of the load during each of a plurality of said half-cycles during a single weld.

Claim 16

A resistance welding control system according to claim 10 wherein the succession of half-cycles includes half-cycles of both polarities.

Claim 17

A resistance welding control system according to claim 14 wherein the signal is indicative of the termination of the flow of current through the load.

Claim 18

A resistance welding control system according to claim 15 wherein the control system includes a controlled rectifier device controlled by the heat control means and in which the sensing means senses the voltage across the device.

Claim 19

A resistance welding control system according to claim 16 wherein the controlled rectifier device is rendered conductive and non-conductive in periodic relation with the source and in which the signal indicative of the power factor of the load is transmitted when the controlled rectifier device becomes non-conductive.

Claim 20

A resistance welding control system according to claim 17 wherein the controlled rectifier device is a pair of to back connected controlled rectifier devices which are alternately conductive.

Claim 21

A resistance welding control system according to claim 18 wherein the controlled rectifier devices are rendered conductive during alternate half-cycles of the source voltage with each becoming non-conductive before the other becomes conductive, and in which the signal indicative of the power factor of the load is transmitted when either of the controlled rectifier devices becomes conductive.

Claim 22

A resistance welding control system according to claim 19 wherein the controllable rectifier device is effective upon actuation to connect a source of pulsating electrical energy to a welding load having an inductive reactance, and timing means for selectively actuating the controllable rectifier device a selectable interval after initiation of timing, and means controlled by the sensing means for initiating the selectable characteristic portion of the timing.

Claim 23

A resistance welding control system according to claim 20 wherein controllable rectifier means is actuated during each of certain of the pulsations of the source.

Claim 24

A resistance welding control system according to claim 21 wherein the timing means actuates the rectifier devices during opposite half-cycles of the alternating current source.

Claim 25

In a resistance welding system for selectively connecting a load having a power factor to a source of alternating voltage during each of at least certain of the half-cycles of the alternating voltage for each weld, a method of controlling the welding system comprising the steps of sensing the power factor of the load, and producing a signal indicative of the power factor of the load, controlling the connection of the load to the source by generating a curve having a selectably variable slope characteristic in response to said signal, initiating the generation of the preselectable slope timing curve for selecting the percent heat fed to the load, and disabling the power factor sensing system during a selected portion of the first half cycle of the weld.

Claim 26

In a resistance welding system for selectively connecting a load having a power factor to a source of alternating voltage during each of at least certain of the half-cycles of the alternating voltage for each weld, a method of controlling the welding system comprising the steps of sensing the power factor of the load, and producing a signal indicative of the power factor of the load, controlling the connection of the load to the source by generating a curve having a selectably variable slope characteristic in response to said signal, initiating the generation of the preselectable slope timing curve for selecting the percent heat fed to the load, and disabling the power factor sensing system during a selected portion of the first half cycle of the weld.