Claims
- 1. A workbench capable of clamping a workpiece, comprising:
- a laterally disposed work table mounted on a support structure;
- a clamping member positioned above and movable relative to the work table and configured to clamp such a workpiece between the clamp and the work table;
- a foot treadle pivotally mounted on the support structure;
- a lever pivotally connected at a first position to the support structure and at a second position to the clamping member;
- a connecting member pivotally connected to the foot treadle;
- a compression spring disposed between the lever and the work table, the spring being connected at a first end to the lever and at a second end to the connecting member such that downward motion of the connecting member compresses the compression spring when such a workpiece is being clamped; and
- a locking mechanism which locks the compression spring in a compressed position.
- 2. The device of claim 1, wherein the locking mechanism comprises:
- a cylindrical housing having an internal bore having an internal periphery, the housing further having along the internal periphery a plurality of parallel longitudinal grooves and a latitudinal annual groove intersecting the lower end of the longitudinal grooves, the bore being further sized and the cylindrical housing being positioned to receive the compression spring in use;
- a laterally disposed annular plate rotatably connected to the connecting member at the second end of the compression spring, the plate including a plurality of fingers sized and positioned to mate into and longitudinally move along the longitudinal grooves of the cylindrical housing when the spring is positioned in the cylindrical housing; and
- the fingers and annular groove each having camming surfaces sized and positioned such that upon engagement of the respective camming surfaces, the annular plate is selectively rotated to an intermediate locked position and to a released position.
- 3. The workbench of claim 1, further comprising spring means for biasing the clamp away from the work table.
- 4. The device of claim 1, further comprising means for adjusting the position on the clamping member at which the lever is pivotally connected.
BACKGROUND OF THE INVENTION
This is a divisional of application Ser. No. 237,770, filed Aug. 29, 1988 now U.S. Pat. No. 4,909,495.
1. Field of the Invention
This invention relates to a workbench capable of clamping a workpiece, and more particularly to a foot operated workbench capable of clamping workpieces of various thicknesses in a generally horizontal position.
2. Description of the Related Art
Various workbenches have been developed which include clamping mechanisms for clamping items to be worked on, such as doors, boards, bicycles, etc. These workbenches generally include a hand operated clamp. The operator places the item to be worked on in the clamp and tightens the clamp by hand to grip the workpiece in a supported position. The clamping mechanisms of such workbenches generally hold the workpiece in a substantially vertical position. Additionally, while some of the clamping mechanisms can accommodate limited sizes of workpieces horizontally, it has been found that the mechanisms often fail to securely hold the workpieces when horizontally disposed.
Quite often, however, it is more convenient, and even necessary for the operator to have the workpiece disposed in a horizontal position above the ground. For example, if the operator desires to sand or saw a wide piece of lumber or other large workpiece, it would be easier to work on the material if it were positioned and clamped in a horizontal orientation. In the current methods known to the inventors, however, the worker typically places the material unclamped on a horizontal surface, such as across two conventional saw horses positioned next to each other. This arrangement causes a substantial disadvantage in that the workpiece is vulnerable to sliding or falling off the horizontal surface on which it is supported.
A further disadvantage experienced by many clamping workbenches lies in the provision of a hand operated clamping mechanism. With such mechanisms, the operator's hands are occupied to engage and disengage the clamp, and are not free to hold or position the workpiece. It is desirable for the worker to have his hands free to handle the workpiece during the clamping operation.
Accordingly, it is desirable to provide a clamping workbench which minimizes or eliminates the above disadvantages of many prior devices.
The present invention addresses the disadvantages of prior devices by providing a workbench which horizontally supports a workpiece and utilizes a foot-operated clamping mechanism for holding the workpiece horizontally.
In accordance with one aspect of the present invention, a workbench is provided which is capable of clamping workpieces of various thicknesses. The workbench includes a laterally disposed work table mounted on a support structure. The workbench also has a clamping member which includes a clamp positioned above the work table and configured to clamp such a workpiece between the clamp and the work table. The bench further includes a foot treadle pivotally mounted on the support structure, and a linkage interconnecting the foot treadle with the clamping member. Rotation of the foot treadle in a first direction moves the clamp into clamping relation with the work table, and rotation of the foot treadle in a second direction moves the clamp away from the work table. Means are preferably provided for locking the clamp in clamping relation with the work table.
In one embodiment of the present invention, the workbench also includes spring means for biasing the clamp away from the work table. In this embodiment, when the clamp is disengaged to release the workpiece, the biasing spring means moves the clamp upwards and away from the work table to totally release the workpiece, and to prepare the bench to receive another workpiece.
In another embodiment of the present invention, the linkage which interconnects the foot treadle with the clamping member includes a laterally disposed lever pivotally connected at a first position to the support structure and at a second position to the clamping member. The linkage also includes a connecting member pivotally connected at a first position to the foot treadle and at a second position to the laterally disposed lever. The point at which the connecting member is pivotally connected to the laterally disposed lever lies between the two pivot connections of the lever with the support structure and the clamping member. In this embodiment, when the foot treadle is rotated in the first direction, the connecting member is thereby pulled in a downward direction. This resultantly rotates the laterally disposed lever downward about the point at which it is pivotally connected to the support structure, thereby pulling the clamping member downward to engage the clamp with the workpiece.
In yet another preferred embodiment, the linkage includes spring means for providing increasing clamping force upon continued rotation of the foot treadle in the first direction after the clamp has engaged a workpiece being clamped. In this embodiment, the worker may place a workpiece on the work table so that a portion of the workpiece is disposed beneath the clamp. The worker rotates the foot treadle (e.g. by stepping down on it) in the first direction until the clamp comes into contact with the workpiece. The worker then continues to rotate the foot treadle in the first direction, which provides increasing clamping force on the workpiece. The worker may continue to rotate the foot treadle in the first direction until a sufficient force is exerted to securely clamp the workpiece. The bench then includes means for locking the spring means in such position so as to provide continued clamping force upon such a workpiece being clamped when the workers foot is removed from the treadle.
In the preferred embodiment of the present invention, the workbench includes a laterally disposed work table mounted on a support structure, and a clamping member positioned above the work table and configured to clamp a workpiece between the clamp and the work table. A foot treadle is pivotally mounted on the support structure. The workbench also includes a laterally disposed lever pivotally connected at a first position to the support structure and at a second position to the clamping member. The lever includes a bore. A connecting member is provided which is pivotally connected to the foot treadle and extends through the bore of the lever. A compression spring is disposed between the lever and the work table. The spring is connect a first end to the lever and at a second end to the connecting member such that downward motion of the connecting member compresses the compression spring when a workpiece is being clamped. Means are also provided for locking the compression spring in a compressed position.
It should be understood that when the term "connected" or "connection" is used, the connection can be a direct connection, or an indirect connection by means of intermediate parts. Thus, for example, the compression spring of this embodiment may be directly connected at its second end to the connecting member, or the spring may be connected to a spring cap, and the spring cap in turn connected directly or indirectly to the connecting member.
In a preferred aspect of this embodiment, the spring locking means includes a laterally disposed annular plate positioned above the second end of the compression spring. The plate has a bore through which the connecting member extends, and a plurality of fingers extending laterally at spaced distances around the circumference of the plate. Means are provided for retaining the annular plate in a freely disposed position above the second end of the spring. A cylindrical housing is provided in surrounding relationship with the compression spring. The housing has a hollow cavity through which the connecting member and compression spring extend. The housing includes a plurality of parallel longitudinal grooves along the internal periphery of the housing into which the fingers of the plate extend. The fingers and parallel longitudinal grooves are operable to restrict lateral rotational motion but allow axial motion of the plate. The housing also includes an annular groove along the internal periphery of the housing interconnecting the lower ends of the parallel longitudinal grooves. The annular groove is operable to receive the fingers of the plate from the lower ends of the parallel grooves when the spring is compressed, laterally rotate the fingers of the plate to an intermediate position laterally between the parallel grooves, and laterally rotate the fingers to the parallel grooves to release the spring.
In this embodiment, the foot treadle may be moved in the first direction so that the clamp engages a workpiece. After engagement, further rotation of the foot treadle in the first direction pulls the annular plate downwards and compresses the compression spring. The fingers of the plate are guided down the parallel grooves of the housing to the annular groove. When the fingers reach the annular groove, further downward rotation of the foot treadle rotates the plate laterally to a position such that release of the treadle advances the fingers of the plate to an intermediate position. The foot treadle is then released. This locks the compression spring in a compressed position, and the workpiece is effectively clamped.
To release the workpiece, the foot treadle is again rotated in the first direction, thereby laterally rotating the annular plate so that the fingers of the plate are rotated to an intermediate position. The foot treadle is then released to rotate in the second direction, such that the fingers and plate are rotated and are free to move axially up the parallel grooves to release the spring from its compressed position.
In a preferred aspect of this embodiment, means are provided for adjusting the position on the clamping member at which the laterally disposed lever is pivotally connected in order to be able to clamp a greater range of thicknesses of workpieces.
US Referenced Citations (12)
Foreign Referenced Citations (10)
| Number |
Date |
Country |
| 295589 |
Dec 1916 |
DE2 |
| 929271 |
Jun 1955 |
DEX |
| 1932856 |
Jan 1971 |
DEX |
| 8118370 |
Oct 1981 |
DEX |
| 3150665 |
Jun 1983 |
DEX |
| 53356 |
Oct 1945 |
FRX |
| 1358869 |
Mar 1964 |
FRX |
| 155841 |
Sep 1932 |
CHX |
| 579207 |
Jul 1946 |
GBX |
| 2150880 |
Jul 1985 |
GBX |
Non-Patent Literature Citations (1)
| Entry |
| PCT International Search Report (International Application No. PCT/US89/03692). |
Divisions (1)
|
Number |
Date |
Country |
| Parent |
237770 |
Aug 1988 |
|
Patent Grant
5120035
