US 5,225,025 A · Apparatus and method for resistance welding

Abstract

A method and apparatus for automated resistance welding of materials is provided. The material may be thermoplastic material. The material has a layer of a second material adjacent thereto. The second material is a dissimilar material which may be applied as a film or a coating on the first material, or the second material may be a separate layer placed adjacent the first material. A heating element is placed in the interface between overlapping portions of the two pieces of material to be welded together. The layers are directly adjacent to the heating element. The layers can be consolidated onto the heating element if desired. The heating element can be composed of carbon fibers in a polymer matrix. The heating element is supplied with current to generate resistive heating. The heating causes melting of the layers adjacent to and contacting the material. Pressure is applied to the area being welded to fuse the materials together. A lower pressure may be applied as a clamping force to areas adjacent to the welded area. The welding may be performed in a step wise fashion to separate weld segments or substantially completely to the entire weld joint. A cooling mechanism is also provided. The weld is simultaneously inspected for the occurrence of melting and for bond quality. A control system is provided for full automation of the system.

Claims24

Dependent claims

Resistance welding apparatus for welding at least two pieces of material comprising

support structure means for receiving and retaining said pieces of material,
electrical resistance heating element means for positioning between said pieces of material and generating resistant heat in a weld area between said pieces of material forming a weld stack,
pressure application means for applying first pressure to said weld area,
control system means operatively associated with said heating element means and said pressure application means and
carriage means for establishing relative movement between said weld stack and said support structure in sequential steps such that a weld cycle is performed on a plurality of said weld areas.

2 more elements

Resistance welding apparatus for joining at least two pieces of thermoplastic material, each said piece of material having adjacent thereto a layer of a dissimilar material composed of a polymer having at least one of a melting point or glass transition temperature at least as low as that of said piece of material, with at least a portion of one piece of said thermoplastic material overlapping a portion of the other of said pieces of material, the welding apparatus comprising

support structure means having movable carriage means for retaining said pieces of material and said layers and for sequentially moving said pieces of material and said layers through said apparatus,
electrical resistance heating element means for positioning between said pieces of material and generating heat in a weld area positioned in an interfere between two adjacent surfaces of said layers, said pieces of material having said layers and said heating element therebetween forming a weld stack thereby, said heating element means being connected to current supply means for passing current through said heating element means to generate resistance heating and initiate melting of said layers,
a plurality of pressure application cylinders, at least one of said cylinders being a high pressure cylinder having a piston rod to which a pressure foot is connected, said pressure foot engaging a segment of said weld stack for applying pressure thereto to join said pieces of material together, and at least one low pressure cylinder having means for applying low pressure to said weld stack to an area adjacent to said segment engaged by said high pressure foot, and
computer control means operatively connected to said heating element means, said pressure cylinders, and said carriage means for controlling said apparatus to sequentially perform a weld cycle on successive segments of said weld stack.

1 more element

Dependencies are inferred from the claim text.

Apparatus and method for resistance welding

Life of this patent

Apparatus and method for resistance welding

Life of this patent

Abstract

Claims24