Metal fusion bonding – Including means to move or guide applicator
Patent
1997-12-22
2000-05-09
Ryan, Patrick
Metal fusion bonding
Including means to move or guide applicator
228 443, 901 42, B23K 3702, B23K 3700, B25J 1100
Patent
active
060591692
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a spot welding system using robots.
BACKGROUND ART
Spot welding systems using robots with spot welding guns are well known and widely adopted in an assembling process of an automobile body, for example. In general, the spot welding is not carried out only on a single welding spot but is practically carried out on a number of welding spots, especially in the assembling process of an automobile body.
Thus, in conventional spot welding systems, there is adopted a layout in which a plurality of articulated robots are arranged in a row to laterally project from an upright wall or to be suspended from a structure such as a ceiling or a beam. In some cases, instead of using an existing structure, a frame dedicated for installing robots is provided.
An object of welding such as an automobile body is transferred along a line which passes near the robots arranged in a row. Usually, the transferring action is intermittently repeated to stop successively at respective operating stages, where the spot welding is carried out on required spots.
However, in the conventional spot welding system using articulated robots encompass problems in efficiency of operation and space utilization. Specifically, it is difficult to arrange the articulated robots close to one another because of their structure or shape, and therefore it is impossible to take advantage of a high-density layout for improving the operational efficiency and for saving space.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a spot welding system in which a plurality of robots can be arranged closer to one another to improve efficiency of spot welding and save space.
A spot welding system of the present invention adopts parallel link robots, each constituted by a parallel link having a plurality of expandable/retractable arms and a wrist mounted on a distal end of the parallel link and having a plurality of rotary drive axes, as robots to be densely arranged in row.
More specifically, in the spot welding system of the present invention, the parallel link robots are arranged on a frame closer to one another either to project laterally from the frame or to be suspended therefrom. A spot welding gun is attached to the wrist of each robot.
In a preferred embodiment, the frame on which the robots are arranged is movable along a conveying direction of a workpiece to be welded. Spot welding can be performed while tracking the workpiece by the movable frame .
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view showing a schematic layout of a spot welding system according to a first embodiment of the present invention;
FIG. 2 is a partially enlarged view showing an arrangement on a base portion of a frame of the spot welding system shown in FIG. 1;
FIG. 3 is a perspective view showing a schematic layout of a spot welding system according to a second embodiment of the invention;
FIG. 4 is a block diagram showing a principal part of a controller which can be used in the embodiments of the invention; and
FIG. 5 is a diagram showing a layout of articulated robots employed in a conventional spot welding system and a layout of parallel link robots employed in the invention.
BEST MODE OF CARRYING OUT THE INVENTION
In FIG. 1, a reference symbol S1 denotes a traveling direction of a conveyor (not shown) for conveying a workpiece (e.g., an unfinished automobile body assembly) W, and the traveling direction coincides with a X-axis direction of a work coordinate system .SIGMA.. Guides 14 are laid on a structure such as a floor along the traveling direction of the conveyor, and a frame 10 is movably mounted on the guides 14 in a direction indicated by an arrow S2.
The frame 10 comprises an upright wall portion 11 and a base portion 12 in L-shape, and reinforcing members 13. A camera CM for detecting a location of the workpiece W is disposed at an appropriate position on the upright wall portion 11. The camera CM constitutes a visual sensor together with an image processing unit incorporate
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Nihei Ryo
Okada Takeshi
Fanuc Ltd
Ryan Patrick
Stoner Riley
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