Material or article handling – Vertically swinging load support – Grab
Reexamination Certificate
1998-03-30
2001-07-24
Underwood, Donald W. (Department: 3652)
Material or article handling
Vertically swinging load support
Grab
C198S468600, C198S475100, C198S750140, C198S797000
Reexamination Certificate
active
06264418
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a workpiece positioner which is adapted to move a workpiece from a load/unload zone to a work zone spaced from the load/unload zone. More particularly, it relates to a workpiece positioner which is capable of maintaining a workpiece in a substantially constant orientation as it moves the workpiece from the load/unload zone to the work zone and vice versa. In another embodiment, the workpiece positioner is capable of rotating the workpiece about an axis extending through the workpiece as it indexes the workpiece from the load/unload zone to the work zone and vice versa.
BACKGROUND OF THE INVENTION
Workpiece positioners are known which are capable of moving a workpiece from a load/unload zone to a work zone where, for example, an arc welding operation is performed on the workpiece. One known workpiece positioner includes a movable beam or frame which is capable of rotating back and forth through an angle of about 180°. First and second workpiece holders are positioned on the movable frame. As the frame rotates from the load/unload zone to the work zone, the workpiece is inverted, i.e., rotated 180°. With some workpieces, it is necessary that the workpiece be returned to its initial orientation before work begins on the workpiece. In order to effect rotation of the workpiece back to its initial orientation, an indexing device is provided.
The indexing device is mounted to a fixed frame. Once the workpiece holder and its workpiece have been moved to the work zone, a portion of the indexing device extends to the workpiece holder and effects rotation of the holder through 180°. Hence, after rotation, the workpiece is in substantially the same orientation in the work zone as it was when loaded onto the workpiece holder in the load/unload zone. However, due to this indexing step, there is a time delay after the workpiece has been moved to the work zone before work may begin on the workpiece. This time delay or added cycle time is undesirable.
SUMMARY OF THE INVENTION
In accordance with a first embodiment of the present invention, a workpiece positioner is provided which uses gravity to maintain a workpiece in a substantially constant orientation as the workpiece is moved from a load/unload zone to a work zone. In accordance with a further embodiment of the present invention, a workpiece positioner is provided which is capable of effecting rotation of a workpiece about an axis passing through the workpiece simultaneously with the movement of the workpiece from a load/unload zone to a work zone. In both embodiments, the workpiece is in substantially the same orientation in the work zone as it was when loaded onto the workpiece holder in the load/unload zone. Thus, cycle time is reduced in both embodiments as it is not necessary to index the workpiece to its initial orientation once it has moved into the work zone. Further with regard to the first embodiment, the overall cost of the device is substantially reduced as a driven indexing device is not required.
In accordance with a first aspect of the present invention, a workpiece positioner is provided which is adapted to move a workpiece from a load/unload zone to a work zone spaced from the load/unload zone. The workpiece positioner comprises a first stationary frame, a second frame coupled to the first frame so as to be rotatable relative to the first frame about a first axis, a first drive device for effecting rotation of the second frame about the first axis, and a first workpiece holder adapted to releasably receive a workpiece. The first holder is rotatably mounted to the second frame so that the workpiece holder and the workpiece are maintained in a substantially constant orientation relative to the first frame as the second frame is rotated about the first axis.
The workpiece holder and the workpiece are rotated by way of gravity as the second frame is rotated about the first axis.
The workpiece positioner preferably further comprises a locking device fixedly mounted to the second frame. The locking device is adapted to engage the first workpiece holder to maintain the first workpiece holder in a substantially fixed position relative to the second frame when the workpiece holder is located in one of the load/unload zone and the work zone. The locking device comprises a piston/cylinder unit having a piston which is movable between extended and retracted positions. The piston engages the workpiece holder when positioned in its extended position so as to lock the workpiece holder in a substantially fixed position relative to the second frame. The piston does not engage the workpiece holder when positioned in its retracted position such that the workpiece holder is capable of rotating relative to the second frame.
Preferably, the workpiece positioner further comprises first and second shielding panels which are fixedly connected to the second frame.
The second frame may comprise a first section rotatable about the first axis, and second and third sections fixedly mounted to the first section. The third section is spaced from the second section and the second and third sections are substantially transverse to the first section.
The first workpiece holder preferably comprises a first headstock rotatably mounted to the second section and a first tailstock rotatably mounted to the third section.
The workpiece positioner preferably comprises a second workpiece holder adapted to releasably receive a workpiece and to rotate about a third axis which is spaced from the first and second axes. The second workpiece holder comprises a second headstock rotatably mounted to the second section and a second tailstock rotatably mounted to the third section.
A sensor may also be provided for detecting if the first headstock is properly positioned relative to the second section after the second frame has been rotated about the first axis.
In accordance with a second aspect of the present invention, a workpiece positioner is provided which is adapted to move a workpiece from a load/unload zone to a work zone spaced from the load/unload zone. The workpiece positioner comprises a first stationary frame, a second frame coupled to the first frame so as to be movable relative to the first frame, a first drive device for effecting movement of the second frame relative to the first frame, and a first workpiece holder adapted to releasably receive a workpiece. The workpiece holder is movably mounted to the second frame so that the workpiece holder and the workpiece are maintained in a substantially constant orientation relative to the first frame as the second frame is moved relative to the first frame.
In accordance with a third aspect of the present invention, a workpiece positioner is provided which is adapted to move a workpiece from a load/unload zone to a work zone spaced from the load/unload zone. The workpiece positioner comprises a first frame which is stationary, a second frame rotatably coupled to the first frame so as to rotate about a first axis, a first drive device for effecting rotation of the second frame about the first axis, a first workpiece holder adapted to releasably receive a workpiece and rotate about a second axis which is spaced from the first axis, and a piston/cylinder second drive device coupled to the second frame so as to move with the second frame. The piston/cylinder drive device is adapted to effect the rotation of the workpiece holder about the second axis.
The piston/cylinder drive device may comprise a piston/cylinder unit having a rack and a pinion. The pinion is fixedly connected to the first workpiece holder. The piston/cylinder drive device is capable of effecting rotation of the workpiece holder about the second axis while the first drive device effects rotation of the second frame about the first axis.
In accordance with a fourth aspect of the present invention, a workpiece positioner is provided comprising a first stationary frame having first and second structural elements, a second frame coupled to the first frame so as to be movable relative to the first fram
DeCamp William Harold
Hickle Wade Matthew
Michael Zane Allan
Slanker Daniel Warren
Killworth, Gottman Hagan & Schaeff LLP
Motoman Inc.
Underwood Donald W.
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