Abstract: A resistance welding device is configured for use in combination with a resistance welder having a translating welding electrode. A first arm of the welding device is in a translating rotational engagement with a second arm thereof. The first arm of the device is engageable to a translating electrode from the resistance welder. Translation of the welding electrode of the resistance welder moves first and second electrodes to contact metal therebetween and spot weld the metal.

Abstract: A spot-welding system including a spot-welding gun including a movable part including a movable electrode, and a drive part that drives the movable part, a controller that controls the drive part, an applied pressure sensor that measures an applied pressure from the movable electrode of the spot-welding gun, and an own-weight calculator that calculates an own weight of the movable part based on the applied pressure detected by the applied pressure sensor in two different postures of the spot-welding gun that places the movable electrode in different movement directions. The controller superimposes a dither signal onto a control signal so as to control the drive part in measuring the applied pressure for use in calculating the own weight of the movable part by the own-weight calculator, and after the own weight is calculated, the controller corrects the control signal based on the calculated own weight.

Abstract: Subjecting an aluminum or aluminum alloy substrate to anti-corrosion and anti-wear treatment that is applicable in particular in the field of aviation for protecting certain mechanical parts of airplanes or helicopters that are subjected simultaneously to corrosion and to wear, including applying to the substrate, a sol-gel treatment step forming a sol-gel layer; and after the sol-gel treatment step, a hard oxidation step forming a hard oxide layer.

Abstract: A welding gun includes: a moving mechanism portion (ball screw mechanism) for moving a movable electrode back and forth; a motor that includes a rotor and drives the moving mechanism portion to move the movable electrode back and forth; and a brake mechanism that prevents rotation of the rotor during a braking operation, wherein the brake mechanism includes an annular brake disc that is attached to an outer peripheral surface of the rotor and rotates integrally with the rotor, and a clamping portion that prevents rotation of the brake disc by clamping the brake disc during the braking operation.

Abstract: A welding assembly (1) for welding two rails (2) of a track includes two rail clamping units (5) movable towards one another in an assembly longitudinal direction (4). A power rail (10) provided for power transmission is configured as an assembly guide (3), extending in an assembly longitudinal direction (4), which is spaced from displacement drives (11) and connects both rail clamping units (5) to one another. The power rail (10) is equipped with a cooling device and displaceable in the assembly longitudinal direction (4) relative to the rail clamping unit (5) equipped with the power rail contacts (8).

Abstract: A disc spring assembly comprises a disc spring support having a radially outer surface and a plurality of annular disc springs arranged in a stack over the radially outer surface of the disc spring support. Each annular disc spring comprises a substantially frusto-conical or dished shape and has a radially inner edge region mounted on the radially outer surface of the disc spring support and a radially outer edge region. At least one separator disc is arranged between two axially adjacent disc springs and has a radially outer portion having opposed axially facing surfaces for receiving the radially outer edge regions of the two axially adjacent disc springs. The radially outer portion of the separator disc have at least one drainage passage for allowing drainage of a liquid from a cavity between the disc springs.

Abstract: There is described a continuity sensing system that operates with a resistance-welding machine. This sensing system measures continuity between the welding electrodes after the welding machine has been initiated and prevents application of high electrode force between the electrodes if the continuity measured is below a reference level. The result is a fully passive system that prevents serious high electrode force that would cause serious pinch-point injury to the operator of the welder. The present invention also includes methods of controlling pneumatic systems on resistance-welding machines to apply low force between welding electrodes until continuity between the welding electrodes has been detected.

Abstract: A continuity sensor determines continuity between welding electrodes by detecting a change in a voltage of a sensed tracer signal across the electrodes from a time when a weld cycle is initiated to a time when the electrodes contact material to be welded. As the electrodes are brought together with low force, the continuity sensor detects changes in the sensed voltage level exceeding a threshold thereby representing continuity and enables the welder to apply the higher welding force. However, if the continuity sensor does not detect a change in the voltage signal, then the welder will not apply the full welding force, thereby preventing pinch-point injury to the operator. The digital continuity sensor reestablishes a baseline for detecting the change in voltage with every new weld cycle such that the digital continuity sensor is not subject to changing voltages or changes in the welder configuration.

Abstract: The resistance spot welding method includes performing actual welding to squeeze, by a pair of electrodes (14), a sheet combination with a sheet thickness ratio of more than 3 in which a thin sheet (11) is overlapped on at least one face of two or more overlapping thick sheets (12, 13), and passing a current while applying an electrode force to join the sheet combination, wherein in the actual welding, a pattern of the current and the electrode force is divided into two or more steps including a first step and a second step to perform welding, and an electrode force F1 in the first step and an electrode force F2 in the second step satisfy a relationship F1>F2.

Abstract: A hand displaceable laser welding gun is configured with an elongated support column extending along a longitudinal axis and made from lightweight material. A support plate is displaceably mounted to the column while supporting thereon an optical head axially which is provided with optics. The optics is configured to direct a laser beam along a path towards a welding zone through a protective window of the optical head. The laser welding gun further is structured with a first arm mounted to the support plate and extending along a longitudinal axis of the gun diametrically opposite to the optical head. The inner surface of the displaceable arm has an inner surface defining a tunnel which is aligned with the optical head and axially traversed by the laser beam, a first axially flowing stream of pressurized gaseous medium, and a second axially flowing stream of gaseous medium.

Abstract: A programmable polarity module that permits rapid on-demand control of the polarities assigned to the welding electrodes retained on a welding gun is disclosed. The programmable polarity module is electrically connectable to the welding gun and a direct current power supply unit to provide direct current to the welding electrodes for exchange during spot welding. A first interchangeable polarity output lug and a second interchangeable polarity output lug of the programmable polarity module permit the polarities of the welding electrodes to be switched without having to electrically disconnect the module from the welding gun.

Abstract: A method of resistance spot welding a steel workpiece to an aluminum or aluminum alloy workpiece involves providing a workpiece stack-up that includes a steel workpiece and an aluminum workpiece and preheating the welding electrode that is meant to contact the aluminum or aluminum alloy workpiece. The method further involves pressing the preheated welding electrode and another welding electrode against opposite sides of the workpiece stack-up, with the preheated welding electrode abutting the aluminum or aluminum alloy workpiece, and passing an electrical current between the two welding electrodes at a weld site to initiate and grow a molten weld pool within the aluminum or aluminum alloy workpiece.

Abstract: The clamp comprises a balancing module that provides one degree of freedom between the mounting and the mobile subassembly that connects together the fixed and mobile arms and a main actuator, and this module has a device for moving this mobile subassembly relative to the mounting in this degree of freedom, for example in translation, the balancing system comprising a flexible device which is connected to the mobile subassembly and which applies a force, in said degree of freedom, to at least one member connected to the mounting, and, in addition, at least one balancing actuator for moving the mobile subassembly to a balanced position relative to the mounting. Particularly applicable to electrical resistance welding clamps.

Abstract: The invention relates to spot welding tongs with tong compensation, including a tong base body (4), two tong arms (6, 7) and a compensation unit (17) movably connecting one of the tong arms (6, 7) with the tong base body (4) and designed to convert a rotational movement into a linear movement, wherein the compensation unit (17) is composed of a drive unit (18) and a connector element (19), and the connector element (19) is eccentrically and movably fastened to an eccentric disc (23) fastened to the drive unit (18). In order to provide such spot welding tongs (1) with a compensation unit, which converts the rational movement into a linear movement, the connector element (19) is designed to be curved in an end region.

Abstract: A resistance welding gun is provided that includes an arm assembly having spaced apart plates. First and second spaced apart blocks interconnect the plates and extend between the plates in a first direction. The first and second blocks are machined to provide a desired spacing between the plates. An electrode arm is arranged between the plates and blocks and supports an electrode end having a replaceable cap in one example. A clamping device applies a clamping load in a second direction transverse to the first direction to secure the electrode arm between the blocks. Lateral alignment between opposing electrode ends is achieved by a movable adjustment assembly on one of the arm assemblies. A pivot pin interconnects the block and electrode arm for permitting rotation of the electrode arm relative to the block. In one example, the adjustment assembly includes an adjustment member that is rotated to laterally move the electrode arm about the pivot pin in a desired position.

Abstract: An improved welding head for creating an in-track weld between a first rail segment and a second rail segment includes a controller having computer-readable instructions read by the controller. The computer-readable instructions include instructions for compensating for rail jerk during in-track welding. The welding head includes a closing force actuator, such as a hydraulic cylinder, for moving the rail segments toward one another. A pressure transducer is monitored during welding to determine a closing force. An impending jerk of the rail movement is detected if an abnormal closing force change is observed, and in response the flow of hydraulic fluid into or out of the hydraulic cylinder is restricted to prevent or minimize the jerk. In addition, when an impending jerk is detected the weld current may be temporarily increased to burn or prevent the formation of short circuit paths between the rails.

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 chamber slowly exhausts through a pre-orifice and a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a retract-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time. Advance of a retract piston assembly is also cushioned. A weld-forward port is no longer provided on a cylinder barrel.

Abstract: A welding method and apparatus are disclosed wherein a plurality of stacks of metal sheets are clamped together in sequence at a welding site between a pair of electrode caps across which welding current is supplied to spot weld together the sheets in each of the stacks in a series of welding operations in a production run. The electrode caps are pressed against the sheets in each of the stacks when each of the stacks is at the welding site with an applied force that includes a closing force to clamp the sheets together in a surface-to-surface interface fit plus a predetermined interjoint force that is increased progressively throughout the production run.

Abstract: A system and method for controlling a piston-cylinder assembly of a welding apparatus, the piston-cylinder assembly including a plurality of pressure chambers, wherein the piston-cylinder assembly is operatively coupled to at least one welding electrode of the welding apparatus so as to effect movement of the electrode in a pre-stroke and weld motion, comprises: connecting to a first port of the piston-cylinder assembly a first fluid pressure, the first port in communication with a first pressure chamber so as to effect the pre-stroke motion of the electrode; and connecting to a second port of the piston-cylinder assembly a second fluid pressure, the second port in communication with a second pressure chamber so as to effect the weld stroke motion of the electrode, wherein the second fluid pressure is different from the first fluid pressure.

Abstract: A weld cylinder having a dual 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 chamber slowly exhausts through a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a weld-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time.

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 chamber slowly exhausts through a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a weld-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time.

Abstract: A welding gun assembly including a housing that defines a first chamber and a second chamber. The assembly also includes a first piston moveably disposed in the first chamber and a second piston moveably disposed in the second chamber. The assembly includes an intensifying rod that can move at least partially into the first chamber due to movement of the second piston within the second chamber. The assembly includes a controller with a pressure sensor operable to detect pressure within the first chamber. The controller is operable to increase pressure within the first chamber up to a predetermined extension pressure while the intensifying rod is disposed outside of the first chamber. The controller is further operable to increase pressure within the second chamber to thereby move the intensifying rod into the first chamber to thereby increase pressure within the first chamber above the predetermined extension pressure.

Abstract: In an electrode for projection welding, an end cover (10) of metal having a through hole (19) is attached to the end of a main body (6) of metal having a cylindrical shape, a guide sleeve (12) of insulation material is disposed in the main body (6), the end of the guide sleeve (12) being formed with a receiving hole (18) for a part (2) in a state in which the receiving hole (18) communicates with the through hole (19) in the end cover (10), and a cooling passage (32) for fluid which cools the guide sleeve (12) is formed.

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: Spot welding gun, having a support, a lower half-gun and an upper half-gun articulated one to the other by a pin, mounted in an oscillating configuration with respect to said support and propping up corresponding welding arms, and a working cylinder including a body and a stem moving with respect to the body so as to control the movement of the upper half-gun and of the lower half-gun. The support has a main plate from which extend two parallel support sides with an articulation axis around which the lower half-gun and the upper half-gun are articulated. The lower half-gun comprises two actuating forks to which the body of the working cylinder is articulated around an axis parallel to the articulation axis. The stem of the working cylinder has an end articulated to the upper half-gun around another axis parallel to said articulation axis.

Abstract: A weld gun having a linkage, which relates pivotal motion of a pair of laterally opposed facing electrodes of the weld gun in a predetermined manner. Based upon the predetermined motion of the electrodes a welding robot positions the electrodes of the weld gun on opposite sides of a workpiece to be welded so that the electrodes simultaneously engage the workpiece on opposite sides.

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 method and apparatus for resistance welding of objects (39) by a spot welding gun which has a C-shaped arm (9), a front electrode (11), a back electrode (13) and a pneumatic cylinder (21). The back electrode is axially moveable a limited distance by the cylinder. The gun is arranged to clamp the objects between the electrode tips (15, 17) by the cylinder (21) and to provide a welding current to flow between the tips. The back electrode is arranged to be released from, moved axially in relation to, and fastened to the cylinder to enable or simplify positioning the gun so that the electrodes are on each side of the objects, removal of the gun from the welded objects and adjustment of the electrode distance (a) based on the thickness (t) of the objects.

Abstract: An actuator designed for use with a welding gun of the type having a first electrode movable in a straight line toward and away from a second electrode supported by a welding arm. The actuator includes a housing with a first and second end. A bushing with a generally square opening defined therethrough is supported in the first end of the housing. An actuator rod extends through the square opening in the bushing and has a first end inside the housing and a second end disposed external to the housing. The actuator rod has an external surface with a generally square cross section such that the external surface engages the square opening to prevent rotary motion of the rod with respect to the housing. A drive mechanism is disposed in the housing and is operable to move the rod with respect to the housing. The drive mechanism may be a pneumatic actuator or a rotary screw drive.

Abstract: A fully programmable servo-pneumatic modular weld gun having closed-loop position and pressure control generally includes a weld gun base module, a pneumatic cylinder with a movable piston having a first welding electrode, a J-shaped gun arm having a first end attached to the base module and a second end having a second welding electrode and a controller for providing closed-loop positioning and pressure control of the first welding electrode. The pneumatic cylinder includes an internal positioning encoder for detecting piston position and transmitting piston position information to the controller to control movement of the piston through a proportional flow control valve and a proportional pressure regulator.

Abstract: A pressure regulator system for a pneumatically- or hydraulically-actuated weld head. The weld head includes a switching valve comprising several ports: an inflow port attached to a source of pressurized gas, preferably air; an exhaust port; a first line port; and a second line port. Two-way valves are provided on the first line port and the second line port. A valve sensor connected to a switch for determining weld force in the weld head is connected to means for simultaneously closing the first line port valve and the second line valve port when a desired weld force is attained between one or more electrodes and a workpiece, thereby maintaining a constant, maximum pressure in the cylinder and consequently maintaining the desired weld force between the electrode(s) and the workpiece during the welding operation.

Abstract: A plurality of pistons are disposed in series in a circular electrode pressure cylinder and each of the pistons is separated. During low pressure output only one piston is used so that the friction force of the other pistons is not transmitted.

Abstract: A resistance welding process in which the welding electrodes are moved at least via a wording piston-cylinder unit, wherein before the start of the welding process, the welding electrode is in a ready position in which it gently touches the workpiece or there is a gap in the tenth of a millimeter range between the welding electrode and the workpiece, and during the subsequent welding process pneumatic force is applied to the working piston-cylinder unit, where the maximum possible stroke of the working piston-cylinder from the position of readiness corresponds to 1 to 40 times the travel of collapsing bulges in projection welding or 1 to 120 times the penetration distance of the welding electrode in an originally hard material becoming pasty during the welding process in spot welding, or 1 to 60 times the penetration distance of the welding electrode in an originally soft material becoming pasty during the welding process in spot welding. The invention also relates to a device for implementing the process.

Abstract: A spot welding apparatus having a welding gun with movable and fixed electrodes carried on an articulating wrist, the apparatus comprising: a) a robotically actuated articulating wrist carrying the gun for movement to and from a welding position for a workpiece; b) a primary cylinder assembly connecting the wrist to the movable electrode of the gun for imposing pressure by such movable electrode to the workpiece and to the fixed electrode during a welding stroke toward the workpiece; and c) a fixing cylinder assembly connecting the wrist to the fixed electrode, the fixing cylinder assembly having (i) a fixing cylinder housing with a movable fixing piston therein connected to the fixed electrode of the welding gun and having a fixing piston stop, (ii) a primary balancing spring acting between the fixing cylinder housing and the movable fixing piston to carry the weight of the gun, (iii) structure for introducing a fixing air pressure into the fixing cylinder housing to urge the fixing piston to a position lock

Abstract: A pressure regulator system for a pneumatically- or hydraulically-actuated weld head. The weld head includes a switching valve comprising several ports: an inflow port attached to a source of pressurized gas, preferably air; an exhaust port; a first line port; and a second line port. Two-way valves are provided on the first line port and the second line port. A valve sensor connected to a switch for determining weld force in the weld head is connected to means for simultaneously closing the first line port valve and the second line valve port when a desired weld force is attained between one or more electrodes and a workpiece, thereby maintaining a constant, maximum pressure in the cylinder and consequently maintaining the desired weld force between the electrode(s) and the workpiece during the welding operation.

Abstract: An apparatus for contacting and applying a force to opposite sides of a workpiece, such as a resistance welding device adapted for use on an automated assembly line. The apparatus is configured to be extremely rigid to ensure accurate movement and positioning of a pair of contacts with respect to a workpiece. The apparatus includes a frame member supported by a base with first and second shafts that are secured to the frame member and slidably supported by the base. The second shaft prevents rotation of the frame member about the first shaft during operation of the apparatus. The frame member carries one of the contacts, and is biased away from the workpiece and toward a second position nearer the workpiece. An extendable member and a link are both pivotably mounted to the frame member, and support an anvil carrying the remaining contact. The link is engaged with the base when the link is in a first rotational position, at which point the second contact is held away from the workpiece by the anvil.

Abstract: A guide pin of a movable electrode is inserted into a hole of a nut fed to an intermediate position between a fixed electrode and the movable electrode, and the movable electrode is then moved down together with the nut to position the nut on a portion to be welded of a workpiece overlying the fixed electrode. An air passage is formed inside of the guide pin. A plurality of air outlets are formed on the periphery of the tip of the guide pin. A pressurized air is supplied to the air passage and is then blown out of the air outlets, so that a blow of the pressurized air is given to the bottom surface of the nut thereby preventing fallout of the nut.

Abstract: In opposition to a lower electrode (31) fixed to a frame (3), an upper electrode (29) is carried by an upper pressing base (23), which is engaged with a vertical guide rail (25) and joined by a resilient slide mechanism to a piston rod (35L) of a hydraulic cylinder (35) connected to a hydraulic circuit operable for an increased distance (L3) between electrode shanks (15, 7) and fastened at a head end thereof to a lower pressing base (33), which is engaged with the guide rail and joined to a piston rod (37L) of an air cylinder (37) fastened at a head end thereof to the frame and connected to a pneumatic circuit operable for supplying a balancing pressure to have the piston rod (37L) thereof contracted to stand with a total load and for relieving the pressure when a mechanical valve (85) is operated with a pedal arm (49) stepped down for starting a welding, while the pneumatic circuit is changed over by a limit switch (57) to force down the lower pressing base.

Abstract: An improved welding apparatus and method of use including a pair of opposed electrodes mounted on arms which are fixed against outward displacement during the application of the welding current. One of the arms includes a cylinder for moving an electrode to and away from the work piece. The cylinder includes a pilot operated check valve which permits a one-way flow of hydraulic fluid while the weld current is applied. The check valve prevents movement of the electrode away from the work piece during expansion of the weld nugget, however, permits inward movement of the electrode after the nugget is softened.

Abstract: A welding gun that prevents rotation of the electrode, including a cylinder and a reciprocating piston assembly having a pair of pistons. In addition to the conventional connecting rod, the pistons are interconnected by an anti-rotation rod radially offset from the connecting rod. The anti-rotation rod extends through a partition fixed within the cylinder, thereby preventing the piston assembly from rotating within the cylinder. The welding gun also includes an internal proximity switch for detecting when the piston assembly is fully retracted.

Abstract: A copper core weld gun assembly is provided with a substantially omega (.OMEGA.) shaped cross-section taken through each arm of the assembly. Concentric copper tubes are provided to carry cooling water and electric current to the electrodes of each arm. Special fittings are provided to insure that cooling water is carried directly to and from the electrodes without contacting the body, thereby eliminating galvanization in aluminum bodies. The design includes wedge-shaped barrel locks, crown-tipped incoming water tubes, thimble-shaped female electrode caps, and provides modular design capability. A modular gun design separates the gun into three fundamental areas: (a) the electrode system; (b) the body/frame system; and (c) the moment arm design.

Abstract: A spot welding device to secure the inner end of a coil of steel to itself to prevent uncoiling. The welding device is carried on an articulated support arm assembly that allows for positioning the welder within the coil on a gimble axis mount for proper access to the entire inner coil surface. Welding tips are selectively held against the welding surface by an extensible guide and engagement assembly.

Abstract: A copper core weld gun assembly is provided with a substantially omega (.OMEGA.) shaped cross-section taken through each arm of the assembly. Concentric copper tubes are provided to carry cooling water and electric current to the electrodes of each arm. Special fittings are provided to insure that cooling water is carried directly to and from the electrodes without contacting the body, thereby eliminating galvanization in aluminum bodies. The design includes wedge-shaped barrel locks, crown-tipped incoming water tubes, thimble-shaped female electrode caps, and provides modular design capability. A modular gun design separates the gun into three fundamental areas: (a) the electrode system; (b) the body/frame system; and (c) the moment arm design.

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: An improved tip dressing process is provided wherein the pressure between the electrode tip of a resistance welder and the cutter of a tip dresser is varied during the tip dressing process. A pressure controller is also provided for controlling the pressure between the electrode tip and cutter during the tip dressing process. The pressure controller may be applied to independently control the tip dressing process of several resistance welders simultaneously.

Abstract: A fusing electrode is mounted on a vertically movable carriage which is raised by a first air actuator and lowered by gravity into engagement with a commutator tang. During a fusing cycle, different pressures are applied between the fusing electrode and the tang by means of a fast-acting air actuator that has a downwardly-extending piston rod engageable with the carriage and which is controlled by a programmable pressure regulating valve. To increase the response time and the force follow through of the second air actuator, the programmable pressure regulating valve is mounted directly on top of the second air actuator with its air outlet located as close to the cylinder of the second actuator as permitted by the air fittings which connect them. Surge tanks associated with the programmable valve assist in ensuring speedy response times.

Abstract: An improved welding apparatus and method of use including a pair of opposed electrodes mounted on arms which are fixed against outward displacement during the application of the welding current. One of the arms includes a pneumatic cylinder for moving an electrode to and away from the work piece. The cylinder includes a piston rod attached to a clutch by a ball screw mechanism. A brake assembly is connected to the unidirectional clutch to prevent outward displacement of the electrodes during expansion of a weld nugget and permitting inward movement of the electrodes to provide indentation of the weld after the nugget softens.

Abstract: A weld force limiting apparatus for use in bench and press type welding units which is capable of advancing a first electrode into contact with production pieces to be welded together. The weld force limiter has a high pressure air source connected thereto for supplying high pressure air to the circuit. When an initiation switch is depressed to begin the welding sequence, provided all conditions are met, the high pressure air is ported through a regulator to regulate the pressure of the air to a very low pressure such that the first electrode advances toward the production pieces under very low pressure, in particular, at a pressure which is non-injurious to the human body.

Abstract: A spot welding machine includes tip electrodes mounted on the tips of the first and second arms, respectively, a pressing actuator for moving at least one of the first and second arms to apply a pressing force to the tip electrodes, an interelectrode distance detector for detecting a distance between the tip electrodes, and a brake for braking the actuator. The distance between the tip electrodes, i.e., interelectrode distance can be set at any desired intermediate distance between the maximum and minimum distances, by braking the actuator when the arms are opened to a desired degree. In this manner, it is made possible to effectively reduce the required operation time, and by suitably performing such a brake control, it is also made possible to effectively lessen an impact caused when the tip electrodes come into contact with plates to be welded. A speed control device may be provided which variably controls the moving speed of the actuator in accordance with the interelectrode distance.