Work holders – With fluid means
Reexamination Certificate
1999-02-02
2001-06-26
Watson, Robert C. (Department: 3723)
Work holders
With fluid means
C269S266000, C269S329000
Reexamination Certificate
active
06250619
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to machine tools and more specifically to a flexible tooling apparatus for providing a support deck for use with machine tools or assembly tools for processing materials.
When machining material with machine tools, assembling material for fastening, or performing other processing, such as heat curing, it is necessary to provide a support system for the material being machined or operated upon. In the past, such supports have comprised a tooling support which substantially conforms to the three-dimensional shape of the part or item being processed. The cost to design, fabricate and store such tooling supports can become prohibitive. A separate tooling support is required for each uniquely shaped item being processed. Often the setup time and effort to prepare and position the tooling die becomes greater than the time involved in actual machining or processing of the part.
To resolve some of the drawbacks of the fixed tooling die situation, variable tooling supports have been developed, for example, as described in U.S. Pat. No. 5,372,357, wherein a plurality of spaced supports are provided in fixed relation to one another and the supports are adjusted heightwise to support the work piece at certain points. The work piece is then either clamped to the supports or the supports provide some sort of clamping through the use of vacuum at the suction cups, for example.
Heretofore, these systems have been quite expensive and complex with a large number of interactions required to provide the appropriate control and power to cause the raising and lowering, as well as the application of vacuum to each of multiple support members. Variable systems which allow movement of the support stanchions in a horizontal plane, as well as the vertical extension thereof, provide even further difficulties given that control wires, power wires and hydraulic or pneumatic or vacuum supply lines are required to also be movable. Maintenance costs related to such systems can be quite high. Over the useful life of such an apparatus, the potential for failure of electrical connections, for example, becomes greater with each successive movement. Further, the cost of such systems is out of the reach of many businesses and such a system may be overly complex for small business applications.
The design of flexible tooling systems is further complicated because of the high temperatures at which many modern manufacturing processes are performed. Such processes include heat treatments, coating applications, and formation of parts from composite materials, which formation can take place at around temperatures of around 400° F. (204° C.). At high temperatures, adequate work piece support can be critical because work pieces tend to deform more readily under their own weight.
Some known clamp mechanisms that fix the extensible supports at the desired extension can loosen at high temperatures, due to thermal expansion of the parts in the clamping assembly. Other clamps tend to bind at high temperatures due to the uneven expansion of the parts in the clamping assembly, thereby preventing releasing of the clamp. Moreover, at high temperatures, the hydraulic systems used to clamp the extendible supports tend to have more problems, such as leaks caused by thermal expansion of fittings and reduced useable lifetime of hydraulic fluids, not to mention the safety issues that arise with flammable fluids in an elevated temperature environment.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, a flexible tooling system is provided wherein a support table has a plurality of apertures therein. Said apertures are adapted for receiving a self-contained actuator in removable relation therewithin.
In one aspect, each position of the support table provides a vacuum and air supply line as well as a bus or network interface so that each position may be addressed separately. The removable actuator has corresponding connectors for receiving the vacuum and air supply as well as for interfacing with the bus, each position having a unique address so that an actuator may be placed at a particular location by insertion into the receptacle at the table aperture and subsequent securing thereto. The actuator may then be addressed on the bus to command the actuator to raise, lower, lock in position and supply vacuum.
In accordance with another aspect of this invention, the actuator includes an extensible member that is fixed in position by a clamp after its height above the table is adjusted to provide support for the work piece. As temperature changes of the flexible tooling system cause dimensional changes of its components, the inventive clamp maintains a secure hold on the actuator, yet does not bind when released, thereby allowing the extension of the extensible member to be changed when the clamp actuating force is removed.
In one aspect of the invention, the clamp uses a bearing element to separate the clamping members that engage each other to fix the position of the extensible member. The bearing element allows relative movement of the clamping members while the clamp is engaged, which prevents binding when the force biasing the parts into engagement is removed.
In another aspect of the invention, a sustained biasing force maintains the clamp engagement, even as components of the clamp change dimensions due to temperature or other changes.
In yet another aspect of the invention, an inside clamping member and an outside clamping member define a space into which a middle clamping member is inserted. As the middle member is pressed into the space, the middle member clearance decreases to zero causes the middle member to exert a force on the inside and outside clamping members, thereby causing the clamping members to releasably fix the extensible member.
In still another aspect of the invention, a clamp includes two clamp assemblies, with the second assembly arranged as a mirror image of the first assembly, thereby providing increased clamping strength and allowing the use of a single clamp release mechanism.
In a preferred embodiment, the clamp uses three collets: an inner collet, an outer collet, and a tapered middle collet, with a set of ball bearings on either side of the middle collet. To engage the clamp, the middle collet is pressed into the gap between the inner and outer collet and biased by springs inward between the ball bearings, forcing the inner collet to frictionally engage the extensible member and the outer collect to frictionally engage the clamp housing, thereby fixing the extensible member in relation to the housing. The ball bearings allow relative movement between the collets while the clamp is engaged to prevent binding, allowing the middle collect to move to a disengaged position when the bias is removed. The springs provide a sustained biasing force to keep the clamp tight, even as the clamp components expand or contract.
It is accordingly an object of the present invention to provide an improved flexible tooling support system.
It is a further object of the present invention to provide an improved flexible tooling support system which allows easy removal and repositioning of support actuators.
It is still a further object of the present invention to provide an improved flexible tooling system wherein individual actuators are passively moved to an appropriate position and then locked into place.
It is yet another object of the present invention to provide an improved flexible tooling system wherein individual actuators are actively operable to position themselves to a precision position.
It is yet a further object of the present invention to provide an improved flexible tooling system with active positioning with a non-servo technology.
It is still another an object of the present invention to provide a flexible tooling system for use in a high temperature environment.
It is a still further object of the present invention to provide a clamp for securely yet releasably fixing the extension of the extensible supports used with a flexible tooli
Cook Larry R.
Erley Robert B.
Starr Robert A.
Sterk Jeffrey A.
CNA Manufacturing Systems, Inc.
Dellett and Walters
Watson Robert C.
LandOfFree
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