Work holders – With fluid means – Vacuum-type holding means
Reexamination Certificate
2000-12-05
2002-08-27
Hail, III, Joseph J. (Department: 3723)
Work holders
With fluid means
Vacuum-type holding means
C269S286000
Reexamination Certificate
active
06439559
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to a vacuum control device used for holding a workpiece, and more particularly, to a vacuum control device which may be activated by placing the workpiece on the vacuum control device without having to first manually invert the vacuum control device.
Vacuum worktables have been designed and used to hold a variety of workpieces for different machining operations including cutting, routing, sawing, and grinding. To prevent the workpiece from moving during the machining process, worktables have been constructed with vacuum pumps that pull air through the worktable to hold the workpiece in place. An example of such a worktable is disclosed in U.S. Pat. No. 5,222,719, to Effener, et al. The worktable disclosed in the Effener patent includes a plurality of recessed openings distributed over the worktable surface. A pod may be placed within each of these recessed openings.
The pod disclosed in the Effener patent is circular with a central boss that extends from a base in an offset manner. The base has a central opening to allow air to pass therethrough. The pod may be placed within the recessed opening in either an activated or deactivated position.
In the activated position, the base sets over the recessed opening with the central boss extending away from the worktable. The air can then pass through the central opening and into the worktable through vent openings positioned adjacent to the walls of the recessed opening when the vacuum pump is started. With air flow, a worker can set a workpiece atop of the central boss to form vacuum between the workpiece and the pod.
A worker must manually invert the pod in the deactivated position to prevent air from passing through the pod to create the vacuum. In the deactivated position, the base sets over the recessed opening with the offset central boss extending to the floor of the recessed opening. This forms an annular chamber between the offset central boss and the wall of the recessed opening. The annular chamber is the only space that communicates with the vented opening and contains the only air that will be evacuated when the vacuum pump is started.
Other manufacturers have developed similar pods to regulate vacuum pressure. Carter Products Company, Inc. of Grand Rapids, Mich. developed a pod that utilizes a ball as a valve to regulate air flow. The ball sets inside a central chamber open to and surrounded by an annular outer chamber. Air may pass through openings at each end of the central chamber. However, a ball check is placed over an opening at one end of the central chamber and guides the ball over the opening when the pod is placed in the deactivated position. The ball closes this opening to prevent air from passing through the pod to the worktable, thus preventing a vacuum to form between a workpiece and the pod.
The Carter pod is placed in the activated position when a worker manually inverts the pod in one of the recessed openings of the worktable. In the activated position, the ball falls to the side of the airflow opening, allowing air to pass through the pod. A worker may then place a workpiece atop of the pod to form a vacuum between the workpiece and worktable. Although a vacuum is eventually formed, the vacuum pump must first evacuate the air from both the central chamber and the surrounding annular chamber to reduce the internal pressure of the pod enough to create the vacuum.
One of the disadvantages and limitations of the pre-existing pods disclosed above is that manual labor is required to activate or deactivate the pods. All pods of the prior art require a worker determine where the workpiece will fit over the worktable and what pods must be activated to safely and securely hold the workpiece in place. In those areas of the worktable where the worker determines no vacuum is required, the worker must manually invert the pods from the activated to deactivated position. The worker is then required to position the workpiece over the activated pods and if any changes are necessary, the worker must repeat this process. This is a time consuming and tedious matter that results in lost time and money.
Further, the pods of the prior art include multiple chambers which must be evacuated before a sufficient negative pressure is created to draw a vacuum between the pods and a workpiece. Multiple chambers create a larger total internal volume. The greater the volume, the longer it takes to remove the gases from those spaces to create the negative atmospheric pressure. Again, this increased waiting time translates to lost time and money.
Lastly, the pods of the prior art do not have a mechanism that adequately prevents the pods from scratching or denting the workpiece. Many workpieces are made from expensive and fragile materials susceptible to scratching, denting or breaking. These workpieces are often damaged during the machining process from the pods which are made of rigid materials.
To overcome the disadvantages and limitations associated with the prior art, an objective of the vacuum control device of the present invention is that it be able to regulate the vacuum pressure without requiring a worker to manually invert or flip the vacuum control device. The vacuum control device should be activated when a workpiece is placed atop of the vacuum control device and deactivated when the workpiece is removed. Further, the vacuum control device should also be able to filter out dust, dirt and other debris from the work environment so that the longevity of the products can be sustained.
Another objective of the vacuum control device is that it be capable of setting in a recessed opening of a worktable removed from a cutting device. This would create a clear machining path and prevent damage to the vacuum control device. In the cutting position, the vacuum control device should be deactivated to prevent air from passing through the vacuum control device. The vacuum control device should also be made from a material that will not damage the cutting device if the cutting device accidentally strikes the vacuum control device when the vacuum control device is not placed in the cutting position.
As a further objective, the vacuum control device should securely set within the recessed opening in either the operating or cutting position so that the workpiece may not slide or move while being machined.
Yet another objective of the vacuum control device is that it should have a single chamber to restrict the internal volume of the vacuum control device. This should allow a rapid evacuation of air from the vacuum control device to efficiently provide sufficient vacuum to hold the workpiece securely and firmly in place so that the workpiece may be worked upon without dangerous and inefficient slipping or sliding. Further, the vacuum control device should be fitted with a mechanism to prevent air from escaping between the vacuum control device and the workpiece while providing scuff or dent resistance.
Finally, it is also an objective of the vacuum control device that all the aforesaid advantages and objectives be achieved without incurring any substantial relative disadvantage.
SUMMARY OF THE INVENTION
The disadvantages and limitations of the background art discussed above are overcome by a vacuum control device for holding a workpiece that is taught by the present invention.
The vacuum control device of the present invention includes a body that may be securely placed within a recessed opening of a worktable. The body has two sides a support side and a seating side, both separated by a flange. The flange extends outwardly from the body and is constructed to rest within a mating ledge surrounding each recessed opening. Either the support side or the seating side can fit within the recessed opening.
The body surrounds an interior chamber that is open on the seating side and is partially closed by a top wall on the support side. The top wall includes a stem aperture flanked by at least one vacuum hole, both providing an opening to the interior chamber. T
Kinnard Steve Patrick
Plitt Eugene T.
Plitt Eugene W.
Bay View Industries, Inc.
Hail III Joseph J.
Reinhart Boerner Van Deuren S.C.
Wilson Lee
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