Abstract: A method of monitoring a resistance welding system is provided. The method utilizes a sensor for isolating and determining movement of a pin that typically supports an object to be welded such as a fastener. The movement of the pin is used to determine various present welding operation parameters to reduce cycle time, and increase efficiency and quality of the weld. The present welding operation parameters are compared to learned or stored welding operation parameters, for example, to determine whether a fault should be generated or whether an acceptable weld was achieved.

Abstract: A tooling fixture is disclosed that includes a weldment having spaced apart lateral members interconnected by opposing side members. Spaced apart trunnions support the side members for rotation about an axis, in one example. A locating pin is arranged between each side member and trunnions to enable quick and accurate location of the tooling fixture relative to the trunnions. The pins are at a right angle relative to the axis, in one example. Tooling plates are removable secured to each of the lateral members. Adjustable brackets are secured to the tooling plates and support tooling that cooperates with a workpiece supported on the tooling fixture. In one example, jack blocks, shims, squaring plates and stops are used to permit precise adjustment and repeatable relocation of the tooling in three directions.

Abstract: A welding assembly is provided for welding a fastener to an object such as a vehicle body panel. The assembly includes a weld gun having first and second electrodes movable relative to one another between an open position and a closed position. The first electrode includes a housing assembly. A pin is received in the housing assembly and is movable when in said closed position between a desired nut position, and upside down nut position, and a no nut position. An optical sensor has a terminal end space from the pin for direction light thereon. The terminal end of the sensor received reflected light from the pin. A sensor control system processes the reflected light into a signal corresponding to one of the desired nut, upside down nut, and no nut positions.

Abstract: A weld cylinder having a single piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force a cushion valve supported by the retract piston assembly and a cushion trip valve supported by a front block cooperate to increase the rate at which the rod moves from the work position to the advanced position so that weld force increases rapidly to minimize increases in cycle time. With both the cushion valve and cushion trip valve move from closed positions to open positions, the rate of fluid flow through the retract piston assembly to increase the rate at which the piston moves within the retract piston assembly.

Abstract: The present invention provides a weld cylinder having a dual piston arrangement. The cylinder has a middle separator separating the cylinder into two cavities. A retract piston assembly is arranged within one cavity. One of the pistons is arranged in the retract piston assembly and the other piston is arranged in the cavity without the retract piston assembly. The pistons support a rod that is moveable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position. However, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion valve and cushion trip valve cooperate to increase the rate at which the rod moves from the work position to the advanced position so that the weld force increases rapidly to minimize increases in cycle time. The cushion valve is supported by the retract piston assembly, and the cushion trip valve is supported by the middle separator.

Abstract: A welding assembly is provided for welding a fastener to an object such as a vehicle body panel. The assembly includes a weld gun having first and second electrodes movable relative to one another between an open position and a closed position. The first electrode includes a housing assembly. A pin is received in the housing assembly and is movable when in said closed position between a desired nut position, and upside down nut position, and a no nut position. An optical sensor has a terminal end space from the pin for direction light thereon. The terminal end of the sensor received reflected light from the pin. A sensor control system processes the reflected light into a signal corresponding to one of the desired nut, upside down nut, and no nut positions.

Abstract: A welding electrode for welding a fastener to an object is provided. The electrode includes a housing assembly with a bore disposed in the housing assembly. A pin is disposed within the bore and is movable along an axis between extended and depressed positions. The pin is retained in the bore by a flange on a lower portion of the pin that extends radially outwardly. A spring is arranged within the bore and urges the pin from the depressed position to the extended position in which a weld nut may be loaded onto the pin. The spring has a compressed length indicative of a spring failure. A stop such as a spring insulator is arranged within the bore adjacent to at least a portion of the spring. The stop extends generally longitudinally in the direction of the pin axis. The stop defines a maximum spring compression length in a fully depressed pin position that may be caused from an improperly loaded weld nut.

Abstract: A soft-touch pneumatic drive unit for welding is provided. The drive unit includes a first section, a second section, and a third section. A piston rod extends substantially throughout these sections and contains a drive piston in the second section and a second drive piston in the third section. Pressurized fluid is supplied through the first section and into the second section to provide a driving force on these pistons. Cushioning fluid is supplied through the first section to the second section to cushion and slow the piston rod as an electrode carried thereby is moved toward a workpiece. A floating piston in the second section then blocks the flow of cushioning fluid from the first section with fluid pressure in the second section then decreasing to atmospheric pressure to enable full welding force to be applied through the drive pistons and the piston rod to the electrode. The cushioning fluid also aids in returning the piston components to the retracted position upon the completion of a weld.

Abstract: A welding assembly is provided for welding a fastener to an object such as a vehicle body panel. The assembly includes a weld gun having first and second electrodes movable relative to one another between an open position and a closed position. The first electrode includes a housing assembly. A pin is received in the housing assembly and is movable when in said closed position between a desired nut position, and upside down nut position, and a no nut position. An optical sensor has a terminal end space from the pin for direction light thereon. The terminal end of the sensor received reflected light from the pin. A sensor control system processes the reflected light into a signal corresponding to one of the desired nut, upside down nut, and no nut positions.

Abstract: A soft-touch pneumatic drive unit for welding is provided. The drive unit includes a first section, a second section, and a third section. A piston rod extends substantially throughout these sections and contains a drive piston in the second section and a second drive piston in the third section. Pressurized fluid is supplied through the first section and into the second section to provide a driving force on these pistons. Cushioning fluid is supplied through the first section to the second section to cushion and slow the piston rod as an electrode carried thereby is moved toward a workpiece. A floating piston in the second section then blocks the flow of cushioning fluid from the first section with fluid pressure in the second section then decreasing to atmospheric pressure to enable full welding force to be applied through the drive pistons and the piston rod to the electrode. The cushioning fluid also aids in returning the piston components to the retracted position upon the completion of a weld.

Abstract: Apparatus for aiding in the manipulation of a tool by supporting the weight thereof is designed particularly for a resistance welding tool. The apparatus includes an overhead support, a curved bar hanging below the support, a trunnion connected to a lower end of the curved bar and a generally horizontal arm rotatably held by and extending out from the trunnion. In particular, the apparatus includes a bail having a circular frame affixed to an outer end of the generally horizontal arm. The bail has two plates affixed together and rotatably carried by the circular frame. The plates have central openings therein to receive the tool and have holes spaced around the central openings to receive fluid fittings to aid in operating the tool. The plates can have manifolds therein to reduce the number of lines required to operate the tool.

Abstract: A method and apparatus for resistance spot welding aluminum comprises polishing the electrode tips periodically after a number of welds. During the spot welding, a coating or dust builds up on the electrode tips and this has been generally assumed to be pure aluminum. However, it has been found that the coating or dust is aluminum oxide which is nonconductive. Consequently, when power is applied to the electrodes there is a slight spitting or explusion at the electrode tips which are in contact with the aluminum surfaces. The electrodes thus become pitted or arced out after a few welds. To overcome this problem, the electrode tips are polished intermittently after a predetermined number of welds. This can be accomplished by a polishing wheel which is moved between the electrodes when they are in an open position.

Abstract: A pressure intensifier drive unit has walls that form a cylinder with an intermediate divider plug separating a working chamber and a pressure intensifying chamber aligned in the cylinder. The working chamber has a working piston and a working piston rod extending from an end of the cylinder. A carrier piston is located between the working piston and the divider plug and has a cylindrical recess receiving the working piston, a hydraulic fluid chamber, and a bore. A locking piston is movably mounted on the carrier piston and locks the carrier piston in place when the working piston rod initially contacts a workpiece. A pressure intensifier piston in the pressure intensifying chamber has a pressure intensifier piston rod extending through a bore in the divider plug and through the bore in the carrier piston into the hydraulic fluid chamber.

Abstract: A low-impact drive unit operates by air under pressure. It includes aligned working and pressure chambers. The working chamber contains a working piston and a working piston rod extending from an end of the chamber. The pressure chamber contains a rear outer piston having a cylindrical recess and a central bore. An inner piston is located in the cylindrical recess and has a main piston rod extending through the bore, a bore in a separator separating the chambers, and is affixed to the working piston, so as to move together. The main rod has a longitudinal passage which supplies air from the pressure chamber to the back of the working piston under certain conditions. After the working piston rod contacts a workpiece, force of air pressure on all three pistons act on the working piston rod. An air return passage is provided to return the various components to their initial position after the working operation is complete.