Computer-integrated multi-gun welding system
First Claim
1. A resistance weld-gun assembly for joining a plurality of workpieces, comprising:
- a resistance welding gun including a fluid-powered cylinder having a cylinder housing and a cylinder rod axially shiftable relative to the cylinder housing, an electrode holder, mechanically coupled to the cylinder rod, for securing an electrode, and an electrode terminal electrically coupled to the electrode holdera weld power source for providing electrical power to the electrode terminal;
an electrode position bracket which is mechanically coupled to the piston rod and extending outward therefrom, said electrode position bracket being electrically isolated from the electrode;
a linear displacement sensor for measuring relative position of the electrode position bracket with respect to the cylinder housing and for generating an electrical displacement signal in proportion to the relative position of the position bracket and the cylinder housing, wherein the displacement sensor is radially displaced from, and parallel to the cylinder rod axis;
a sensor mounting bracket rigidly affixing the linear displacement sensor to the cylinder housing in at least two axial spaced apart locations; and
a weld computer responsive to the displacement sensor for insuring proper pre-weld part fit up and for regulating the power output of the weld power source in real time during the joining of the plurality of workpieces.
1 Assignment
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Accused Products
Abstract
A method and apparatus are disclosed for monitoring and controlling a multi-gun resistance welding apparatus. An embodiment of the system comprises a computer which executes a routine that allows supervision of the multi-gun welding system, a programmable logic controller which controls movement of the guns and gun delivery devices, gun sensors which measure the displacement of gun electrodes, delivery device sensors for determining a location of the gun delivery devices, fixture sensors for measuring the location of a workpiece fixture, a weld controller which applies power to the gun electrodes, and an analog-to-digital converter which converts the outputs of the sensors to digital signals readable by the computer. An embodiment of the weld routine executed by the computer spatially gauges the pre-weld fit-up of the workpieces and inhibits the application of weld power if the fit-up is not within a specified tolerance. The embodiment of the routine detects stuck gun conditions after the weld, and performs a weld analysis to diagnose various faults during the welding based upon electrode position. An embodiment of a retro-fit gun sensor is presented which utilizes an electrode positioning bracket coupled to the electrode. The position of the bracket is measured by means of a linear variable displacement transducer. Using the retro-fit gun sensor, the computer-integrated welding system can be readily incorporated into commercially-available multi-gun welding systems.
57 Citations
50 Claims
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1. A resistance weld-gun assembly for joining a plurality of workpieces, comprising:
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a resistance welding gun including a fluid-powered cylinder having a cylinder housing and a cylinder rod axially shiftable relative to the cylinder housing, an electrode holder, mechanically coupled to the cylinder rod, for securing an electrode, and an electrode terminal electrically coupled to the electrode holder a weld power source for providing electrical power to the electrode terminal; an electrode position bracket which is mechanically coupled to the piston rod and extending outward therefrom, said electrode position bracket being electrically isolated from the electrode; a linear displacement sensor for measuring relative position of the electrode position bracket with respect to the cylinder housing and for generating an electrical displacement signal in proportion to the relative position of the position bracket and the cylinder housing, wherein the displacement sensor is radially displaced from, and parallel to the cylinder rod axis; a sensor mounting bracket rigidly affixing the linear displacement sensor to the cylinder housing in at least two axial spaced apart locations; and a weld computer responsive to the displacement sensor for insuring proper pre-weld part fit up and for regulating the power output of the weld power source in real time during the joining of the plurality of workpieces. - View Dependent Claims (2, 3)
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4. A multi-gun computer-integrated welding system for supervising a joining of a plurality of workpieces, the system comprising:
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a plurality of weld guns, each of the plurality of weld guns comprising a welding electrode, a cylinder assembly having a cylinder housing, and a piston and a piston rod attached thereto for linearly displacing the welding electrode, wherein at least one of the weld guns is positionable between a pre-weld fit-up position and a retracted home position; a device sensor cooperating with a positionable weld gun for determining weld gun locations; a fixture for securing the plurality of workpieces in a welding location; fixture sensing means, cooperating with the fixture, for measuring a location of the fixture; a plurality of displacement sensing means, coupled to each of the weld guns, for measuring displacements of the welding electrodes relative to the corresponding cylinder housings; fit-up verification means, operatively responsive to the device sensor, the fixture sensing means, and the plurality of displacement sensing means, for determining a proper positioning in space of the plurality of workpieces and the positionable weld guns before welding power is applied by determining whether the location of the positionable weld gun, the location of the fixture, and the displacements of the welding electrodes are within or outside a specified rejection region when the welding electrodes are in contact with the plurality of workpieces; and weld power supply, operatively responsive to the fit-up verification means, for initiating an application of electrical power to the welding electrodes if the displacements are outside the specified rejection region, and for inhibiting the application of power to the welding electrodes if the displacements are within the specified rejection region. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A multi-gun computer-integrated welding system for joining of a plurality of workpieces, the system comprising:
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a plurality of weld guns simultaneously cooperating with the workpieces to be joined, each of the plurality of weld guns comprising a welding electrode, a cylinder assembly having a cylinder housing, and a piston and a piston rod attached thereto for linearly displacing the welding electrode, wherein at least one of the weld guns is positionable between a pre-weld fit-up position and a retracted home position; a weld gun positioning device; a device sensor cooperating with a positionable weld gun for determining the weld gun location; displacement sensing means, coupled to each of the weld guns, for measuring pre-weld fit-up and substantially simultaneously measuring displacements of the welding electrodes relative to the corresponding cylinder housings during the joining of the plurality of the workpieces; computing means, operatively responsive to the displacement sensing means, for issuing supervisory commands prior to initiating and during the joining of the plurality of the workpieces based on the device sensor, the internal displacement and weld gun position measured displacements and a predetermined weld schedule, a device sensor cooperating with a positionable weld gun for determining weld gun locations; and control means, operatively responsive to the computing means, for controlling the application of electrical power to the welding electrodes, as a function of the supervisory commands generated by the computing means based on the measured displacement and the predetermined weld schedule. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A computer integrated welding system for joining a plurality of workpieces, the system comprising:
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a weld gun having a welding electrode, a cylinder assembly having a cylinder housing, and a piston and piston rod attached thereto for linearly displacing the welding electrode; a displacement sensor coupled to the weld gun for measuring the displacement of the welding electrode relative to the cylinder housing; a weld power source for controlling an application of force and for controlling an application of electrical power to the welding electrode; a weld computer, operatively responsive to the displacement sensor, for providing a fault signal in the event a good weld is not completed; and a marking device, operatively responsive to the fault signal, for physically marking the workpiece to indicate if a good weld has not been made. - View Dependent Claims (49, 50)
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Specification