Resistance spot welding gun and transformer assembly

• US 4,684,778 A
• Filed: 04/30/1984
• Issued: 08/04/1987
• Est. Priority Date: 04/30/1984
• Status: Expired due to Fees

• Current Assignee: Dimitrios G. Cecil
• Original Assignee: Dimitrios G. Cecil
• Inventors: Cecil, Dimitrios G.
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US06/605,563
• Time in Patent Office: 1,191 Days
• Field of Search: 219/116, 219/86.21, 219/86.25, 219/86.41, 219/86.51, 219/86.33, 219/86.8, 219/89, 219/91.1, 901/42
• US Class Current: 219/89
• CPC Class Codes: B23K 11/315 with one electrode moving on a linear path
• CPC Class Codes: B23K 11/317 Equalizing; Balancing devices for electrode holders

Abstract

An assembly is provided for mounting on an end of a robot arm actuator as an integral spot resistance welding gun and transformer unit. A gun slide support bracket is connected to the transformer and serves to provide a mount for a sliding gun cylinder having a piston connected to one of the jaw electrodes. The lower jaw is removably connected to the cylinder. Roller shunts are used to provide electrical connection between secondary terminals on the transformer and the two electrodes. A proximity switch assembly is advantageously utilized to provide signals to the robot controller indicating a fully retracted position of the jaws.

Claims

1. Resistance welding apparatus comprising:

a transformer;

a bracket connected to the transformer and including a pair of ears projecting upwardly from lateral sides thereof;

two guide shafts, one each connected to each pair of ear projections on the bracket;

a cylinder having leg portions extending from sides thereof slidably mounted on said guide shifts, and a pneumatically actuated piston rod in the cylinder;

a first jaw member removably attached at one end to the cylinder, and a first electrode connected to an opposite end of the first jaw member;

a second jaw member connected at one end to the piston rod and a second electrode connected to an opposite end of the second jaw member;

first and second U-shaped rolling shunts, the first shunt being connected between a transformer secondary terminal and the first jaw, the second shunt being connected between another transformer secondary terminal and the second jaw; and

spring means connected to a rear end of the cylinder for adjusting pressure developed between the two electrodes.

2. The apparatus of claim 1 wherein said first and second jaw members are water cooled.

3. In a resistance welding gun having a pair of electrodes movable between a first welding position and a second retracted position, the improvement comprising:

a slidable cylinder having a piston rod therein connected to one of the electrodes, with the other electrode being connected to the cylinder; and

sensor means for detecting failure of the electrodes to return to their retracted position after welding, said sensor means including first switch means on the cylinder, first actuator means moving with the piston rod for contacting the first switch means when one of the electrodes has been retracted, a second switch means mounted at a fixed location, and second actuator means mounted to the cylinder adapted to become displaced from the second switch means when the other electrode has been retracted; and

means for connecting the welding gun to an automatic positioning device whose position is controlled by an external controller;

whereby signals from the first and second switch means can be used by the external controller to prevent repositioning of the gun if the electrodes do not retract.

4. The improvement of claim 3 wherein the first switch is of the normally open type and the second switch is of the normally closed type.

5. Resistance welding apparatus adapted to be mounted on a robot arm actuator, said apparatus comprising:

a transformer;

bracket means connected to the transformer and supporting a cylinder slidably mounted thereon, said cylinder including a pneumatically actuated piston rod therein;

a pair of electrodes, one of the electrodes being connected to the cylinder and another electrode being connected to the piston rod;

flexible connector means for electrically connecting said transformer to said electrodes;

sensor means for detecting when the electrodes are in a retracted position whereby said signal may be used by a robot controller as precautionary criteria prior to moving the apparatus to a different weld position;

said sensor means includes first switch means mounted on the cylinder adapted to be connected by a first actuator member moving with the piston rod when one electrode is in a retracted position, and a second actuator mounted on the cylinder adapted to become displaced from a second fixed switch means when the other electrode is in a retracted position.

6. Resistance welding apparatus adapted to be mounted on a robot arm actuator, said apparatus comprising:

a transformer;

bracket means connected to the transformer and supporting a cylinder slidably mounted thereon, said cylinder including a pneumatically actuated piston rod therein;

a pair of electrodes, one of the electrodes being connected to the cylinder and another electrode being connected to the piston rod;

flexible connector means for electrically connecting said transformer to said electrode;

wherein said bracket means includes;

a generally T-shaped bracket having a first portion to which said cylinder is mounted and having a transversely extending second portion serving as a faceplate abutting one end of said transformer;

further including legs on said cylinder, a pair of guide shafts onto which said cylinder legs are slidably mounted, and fixed ear projections on said bracket to which said guide shafts are attached.

7. Resistance welding apparatus adapted to be mounted on a robot arm actuator, said apparatus comprising:

a transformer;

bracket means connected to the transformer and supporting a cylinder slidably mounted thereon, said cylinder including a pneumatically actuated piston rod therein;

a pair of electrodes, one of the electrodes being connected to the cylinder and another electrode being connected to the piston rod;

flexible connector means for electrically connecting said transformer to said electrodes; and

a stud connected at one end to rearward portions of the cylinder, a stop member attached to the first portion of the bracket through which said stud is adapted to pass, a spring surrounding said shaft having an end abutting said stop, and adjustment means on the opposite end of the stud for adjusting the tension in the spring.