Work holders – With fluid means – With safety means
Patent
1980-06-25
1982-07-06
Watson, Robert C.
Work holders
With fluid means
With safety means
269 481, B23Q 314
Patent
active
043379320
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to a workpiece holder and, more particularly, to a safety device for the workpiece holder to prevent a workpiece from falling from the workpiece holder.
2. Background Art
In manufacturing large tires for earthmoving vehicles, layers of tire materials, such as uncured rubber, breaker plies and belts, are applied to the exterior surface of a toroidal-shaped core as it is being rotated about its axis. The core remains within the tire carcass during construction and is eventually dissolved as one of the final steps in making the tire. Since the tire materials must be applied to both the sidewalls and the crown area of the carcass, it is desirable to support the core by gripping the inner surface.
Workpiece holders have been devised which include a plurality of slidable elements with gripping devices mounted on a support structure which extend radially relative to a longitudinal axis of the support structure. One such structure is shown in U.S. Pat. No. 4,169,585, issued Oct. 2, 1979 to Ronald E. Dennis, entitled Workpiece Holder, and assigned to the common assignee of the present invention. In the patented structure, a cam engages the inner ends of the slidable elements and is movable along the longitudinal axis between a first position at which the elements are retracted away from the workpiece and a second position wherein the cam engages the inner surface of the elements to cause outward extension and engagement of the gripping devices with the inner surface of the annular core workpiece. In the existing workpiece holders, the cam is actuated by a shaft which extends along the longitudinal axis of the support structure. Since the extendible elements and support structure must rotate, this results in a relatively complex structure. It is therefore desirable to simplify construction of the workpiece holder by eliminating the longitudinal cam-actuating shaft.
In addition, since the cores can be very large in diameter (100 inches, for example) and are rotated during manufacture, means must be provided which will ensure that engagement between the workpiece holder and the core is maintained during operation. Loss of gripping force and detachment of the core from the holder can result in equipment damage or injury to the operator. Heretofore, continued engagement has depended upon the integrity of springs or fluid pressure which actuates the cam. It is, therefore, desirable to provide a safety device which will maintain the cam in its extended-holding position should actuating power to the cam be lost.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF INVENTION
In one aspect of the present invention, the problems noted above are overcome by providing a rotating workpiece holder which is mounted on a solid cantilever shaft. The support structure includes a number of engagement arms which are mounted on the support structure perpendicular to the mounting shaft and which extend radially outward to contact the core. The support arms are extended into engagement with the core by a central cam mounted on the output shaft of a fluid cylinder attached to the support structure opposite the cantilever mounting shaft.
In addition, to maintain the central cam in its operative position, the support structure is provided with a spring-operated latch which engages the rear surface of the cam and prevents relative motion between the cam and the support structure.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an end elevational view of the workpiece holder of the present invention illustrating the radial support arms and the safety latch device;
FIG. 2 is a sectional elevational view of the workpiece holder taken generally along line 2--2 of FIG. 1; and
FIG. 3 is an enlarged partial sectional view of the safety latch device taken along line 3--3 of FIG. 1 illustrating the safety latch rod and its spring actuated fluid return cylinder.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawings, a workpi
REFERENCES:
patent: 1447242 (1923-03-01), Fritz
patent: 1624151 (1927-04-01), Shevlin
patent: 2736531 (1956-02-01), Wilson
patent: 3770032 (1973-11-01), Stull
patent: 3993286 (1976-11-01), Greene et al.
patent: 4169589 (1979-10-01), Dennis
patent: 4251056 (1981-02-01), Maniglia
Dennis Ronald E.
Kizer Richard W.
Caterpillar Tractor Co.
Watson Robert C.
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