US 4,104,724 A · Digital welder control system

Abstract

A digital welder control system for controlling a portable gun welder of the type used in the automotive industry on an assembly line. An 8 bit microprocessor is the main control element of the system. The known cycle time of the microprocessor is used to generate a real time delay which in turn is used to generate a digital phase shift heat control. RAM locations in the microprocessor are used to store medium constants of the welding sequence which were previously stored, in prior art controls, in the position of tap switches or thumbwheel switches. The controller provides diagnostics for six common problems often encountered by welder control systems such as override timeout, half cycling, transformer temperature rises, a low water flow, a shorted SCR, and a change in the heat settings. The controller also provides a maintenance interval counter and compensator control having a four-step stepper. The stepper control is used to automatically increase the weld heat after a preset number of welds to compensate for electrode mushrooming. The controller also checks the setting of address and data thumbwheels to prevent incorrect entries into the welding sequence. The controller also permits entry of data only into RAM locations which are used in the normal sequence of the welder. The controller also utilizes serial communication between a sequence module used to program the microprocessor and the microprocessor to economize on the number of drivers and receivers required and to reduce the power requirements of the controller.

Claims9

Dependent claims

A digital welder control system for a portable gun welder of the type connecting and disconnecting a welding transformer load from an electrical source to control the timing periods of the welding sequence and the level of heat intensity in the weld, comprising:

a means responsive to manual actuation for producing a plurality of output signals representing timing period and weld heat constants of the welding sequence;
a sensing means responsive to the end of current conduction in each half-cycle of a welding period for generating an automatic power factor signal having a timing point which varies with changes in the power factor of the welding installation;
and
a digital control means, responsive to the heat, period, and automatic power factor signals and having a fixed and known cycling time to execute a particular instruction so that by placing the control means in a programmed loop after the automatic power factor signal is sensed, a real time delay is produced, for generating a digital phase shift heat control weld firing signal and for generating each of the timing periods within the weld sequence.

1 more element

In a digital welder control system for controlling a portable gun welder of the type used in automotive industry in an assembly line having a microprocessor as its main control element, a sequence module with operators for programming the weld sequence of the microprocessor including a run/program key switch, address thumbwheels to select an address location in the memory of the microprocessor, data thumbwheels to dial timing period and weld constants to be entered into the memory location dialed by the address thumbwheels, and an enter/reset button for entering the data selected, a method of programming the digital system comprising the steps of:

utilizing a card program worksheet containing the timing period and welding heat constants to be used in a weld sequence;
setting the run/program key switch to the program position;
setting the address thumbwheels to the address location in the memory corresponding to the memory located on the programming card for which data is desired to be entered;
setting the data thumbwheel to the number that is to be entered into the location dialed by the address thumbwheels which corresponds to welding schedule on the programming card;
and
pressing and releasing the enter/reset button to enter the constants into the microprocessor for controlling weld sequence.

3 more elements

Dependencies are inferred from the claim text.

Digital welder control system

Life of this patent

Digital welder control system

Life of this patent

Abstract

Claims9