Patent Application
20060027541
This invention relates to non-contact fusion welding and, more particularly, to a workpiece clamping apparatus and method for insuring intimate and continuous contact between the workpieces during non-contact fusion welding.
Non-contact fusion welding techniques such as laser welding, electron beam welding, plasma welding and arc welding are known in the art for joining metal and polymer workpieces. In order for a non-contact fusion weld to be properly formed, the workpieces to be joined must be in continuous contact along the entire length of the weld. Any gaps between the workpieces can result in malformed pieces or a weld having insufficient strength. Previously devised clamps for non-contact fusion welding are sometimes inadequate for insuring continuous contact, since these clamps may only engage a portion of the workpiece at a location separate or apart from the weld site. As a result, the workpieces may not be adequately forced together to insure continuous contact during the welding process.
Thus, it is desirable to provide a clamping apparatus for non-contact fusion welding operations which insures intimate and continuous contact between the workpieces or parts along the entire length of the weld site. It is also desirable to provide a clamp for non-contact fusion welding which can be configured in a variety of shapes to conform to any desired weld pattern or part shape.
The present invention provides non-contact fusion welding apparatus having a pair of programmable clamps carried by universally movable positioners. The positioners are programmed to move the clamps sequentially adjacent a weld path or sequentially adjacent selected weld locations so that the clamps, engage and support opposite surfaces of a stacked pair of workpieces during welding to insure intimate and continuous contact between the stacked workpieces along the entire length of the weld.
In an exemplary embodiment, the non-contact fusion welding apparatus employs a welding laser. However, other such non-contact welding devices such as an arc welder, a plasma welder or an electron beam welder may be substituted for the welding laser.
A first programmable positioner in the form of a programmable robot includes a base having a jointed arm carrying the welding laser and an upper clamping member (upper clamp). Alternatively, the robot may have a jointed arm carrying an upper clamping member and another jointed arm carrying a welding laser. The non-contact fusion welding apparatus further includes a suitable holding fixture or support adapted to carry a temporary structural assembly formed of stacked metal or polymer workpieces. The apparatus also includes a second programmable positioner located beneath the support.
The second positioner includes a base that is linearly movable along a rail extending about the length of the support. The base carries a positionable lower clamping member (lower clamp) adjustably supported by a plurality of control arms. The control arms and the base are adjustable by programmable controls to adjust the position of the base along the rail and the attitude and position of the lower clamp relative to the base.
A structural assembly comprising a pair of workpieces in temporary assembly with opposing surfaces in contact for laser welding at selected locations is carried by the support of the welding apparatus. The first and second positioners subsequently position the upper and lower clamps adjacent a first selected location so that the clamps engage opposite surfaces of the structural assembly to hold the workpieces together. The laser is then operated to form a laser weld at the first selected location adjacent the clamps.
After welding the first selected location, the clamps are repositioned adjacent subsequent selected locations. As the clamps engage the assembly at the subsequent locations, the laser is re-aimed at the respective locations to sequentially form welds at each of the selected locations. Once all of the locations are welded, the structural assembly is completed and removed from the support.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.
Throughout the following description and drawings, like reference numerals refer to like components shown in the various figures of the drawing.
Referring to
The non-contact fusion welding apparatus 22 further includes a suitable holding fixture or support 36 adapted to carry the structural assembly 10. The apparatus 22 also includes a programmable positioner 38 located beneath the support. The positioner 38 includes a base 40 that is linearly movable along a rail 42 extending along the length of the support 36. The base 40 carries a positionable lower clamping member (lower clamp) 44 adjustably supported by a plurality of control arms 46. The control arms 46 and the base 40 are adjustable by programmable controls, not shown, to adjust the position of the base along the rail 40 and the attitude and position of the lower clamp 44 relative to the base.
In operation, the spatial coordinates of the structural assembly 10 are programmed into the positioners 24, 38. Structural assembly 10, comprising workpieces 12, 14 in temporary assembly with opposing surfaces in contact for laser welding at selected-locations, is placed onto the support 36 of the welding apparatus 22. The first and second positioners 24, 38 subsequently position the upper and lower clamps 34, 44 adjacent a first selected location 48 so that the clamps engage opposite surfaces 16, 18 of the structural assembly 10. The laser 32 is then aimed toward the first selected location 48 and energized to form a laser weld at the first selected location. If desired, the laser may form a seam weld for a distance adjacent the clamps to form a seam weld at the selected location.
After a weld is created at the first selected location, the laser 32 and the clamps 34, 44 may be sequentially repositioned at subsequent selected locations 52 to allow the laser 32 to form multiple spot or seam welds 50 at the subsequent locations. After all of the selected locations 52 are welded, the structural assembly is removed from the support.
In operation, welding apparatus 60 operates similarly to welding apparatus 22 in that the upper and lower roller clamps 66, 68 are positioned oppositely at selected locations 52 of a structural assembly 10 to provide clamping force holding together the workpieces 12, 14 to insure a high quality weld. Positioning arm 64 aims the welding laser 32 at the selected location 52, which is clamped by the roller clamps 66, 68. The laser is then energized to form a weld 50 at the selected location.
As the laser forms the weld 50, the laser 32 and the roller clamps 66, 68 may be moved along their respective surfaces 16, 18, from the selected location 52, to form a seam weld 50 connecting the workpieces 12, 14. As the clamps are moved along their respective surfaces they maintain clamping pressure to insure contact between the workpieces 12, 14. As needed, the positioners 24, 38 reposition the roller clamps 66, 68 to maintain optimal clamping pressure and contact along the contours of the structural assembly 10. As a result, a high quality laser seam weld 50 can be formed between the workpieces 12, 14.
While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.
