Clamp for a power tool

Abstract: In accordance with the present invention, an improved clamping apparatus (10) is employed. The clamping apparatus (10) includes a clamp body (2) having a first (24) and a second (25) end, an attachment member (1) having a first and second end, the first end of the attachment member (1) having a first and second end, the first end of the attachment member (1) connected to the first end (24) of the clamp body (2), a clamping member (5) having a first end and a second end, the clamping member slidably connected to the second end (25) of the clamp body, a locking button (3) for locking the clamping member (5), and a spring (9) biasing the button (3) towards a locking position. Preferably, the clamping member (5) includes a pad (7) disposed at the second end of the clamping member. Further, the clamping member may include a knob (4) disposed at the first end of the clamping member.

Description: This invention relates generally to clamps for power tools according to the preamble of claim 1 (see, for example, US-A-5 582 089) and, more particularly, to a clamp that is easy to install on the power tool and to adjust against a workpiece. When cutting a workpiece on a power tool, such as a mitre saw, chop saw, drill press, table saw, etc., it may be desirable to clamp the workpiece to the base of the power tool or against a fence attached to the power tool. However, many individuals do not use available prior art clamps as they can be difficult to adjust when clamping or releasing a workpiece and/or difficult to install on the power tool. For example, some prior art clamps, such as the one illustrated in US Patent No. 5,582,089, requires a user to repeatedly rotate a threaded rod to clamp or release the workpiece. It is therefore an object of this invention to provide a clamp that is easy to adjust when clamping or releasing a workpiece and that is easy to install on the power tool. In accordance with the present invention, there is provided a clamping apparatus for a power tool comprising a clamp body having a first and second end; an attachment member having a first and second end, the first end of the attachment member connected to the first end of the clamp body; and a threaded clamping member having a first end and a second end; characterised in that the clamping member is slidably connected to the second end of the clamp body and the clamping apparatus further comprises a button moveable between an unlocking position and a locking position; and a spring disposed between the clamp body and the button such that the spring biases the button into the locking position; wherein the button has a thread receiving portion capable of engaging the clamping member and an upper surface, with a lip wherein the thread receiving portion is disengaged from the clamping member when-the button is in the unlocking position and, the thread receiving portion is engaged with the clamping member when the button is in the locking position, whereby rotation of the clamping member when the button is in the locking position moves the upper surface of the button into contact with the clamp body thereby securely locking the clamping member against a workpiece. Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below. The accompanying drawings illustrate the preferred embodiment of the invention according to the practical application of the principles thereof, and in which: Figure 1 is a partial cross-sectional side view of a clamping apparatus according to an embodiment of the present invention; Figure 2 is a cross-sectional side view of the button of this embodiment; The invention is now described with reference to the accompanying figures, wherein like numerals designate like parts. Referring to Figure 1, a clamping apparatus (10) of the present invention is connected to a power tool, such as a sliding compound mitre saw, a drill press, a table saw, etc. Preferably, the clamping apparatus (10) includes an attachment rod (1) for attaching the clamping apparatus (10) to the table portion (20) of the power tool, a clamp body (2), a clamping rod (52) inserted through the clamp body (2), a moveable button (3) for locking and unlocking the clamping rod (52), and a spring (9) for normally biasing the button (3) to a locking position. The attachment rod (1) is preferably cylindrical. The attachment rod (1) is fixedly attached at the first end (24) of the clamp body (2). Preferably, the attachment rod (1) has a decreasing diameter at the lower end, which expands into knob (22). Knob (22) has an upper projecting lip which extends partially around the upper circumference. The attachment rod (1) fits within hole (23) and is secured therein by rotating the upper projection lip so as to engage beneath flat (21). The clamp body (2) can be one of a variety of shapes and is shown in the drawings as one specific configuration for illustration purposes only. Preferably, the clamp body (2) has a bore at its second end (25) that allows the clamping rod (52) to slide therethrough. The clamping rod (52) is preferably opposite and generally parallel to the attachment rod (1). The clamping rod (52) may preferably include a pad (7) at its lower end adapted to contact a workpiece (not shown). The pad (7) may be made of soft material, such as neoprene or rubber, so that it will not indent the workpiece when clamped. Preferably the pad (7) is attached to a cup (6), which in turn is attached to the clamping rod (52) via a joint (8). This joint (8) can be a ball and socket joint or a universal joint. Preferably, the joint (8) will consist of the cup (6) engaging the clamping rod (52) in such manner that the cup will be pivotally mounted to the clamping rod (52), In this manner the pad (7) may accommodate a workpiece which does not have a completely horizontal surface. In addition, the clamping rod (52) preferably includes a knob (4) attached at its upper end to enable a user to push down on the clamping rod (52). The clamping rod (52) is preferably locked in place by the button (3). Referring to Figures 1 and 2, the button (3) is disposed in a cavity (31) within the clamp body (2). The button (3) has a bore (32) that allows the clamping rod (52) to slide therethrough. The clamping rod (52) is threaded. Preferably, the thread of clamping rod (52) has a low pitch, such as the ACME thread per ANSI B1.5-1977, Class 20, or the Powerscrew thread. Accordingly, more travel along the axis of the rod can be obtained with a smaller amount of rod rotation. As shown in Figure 2, the button (3) is adapted to engage the threaded clamping rod (52). The button (3) has a thread receiving portion (51) that engages the threads (50) of the clamping rod (52). The thread receiving portion (51) is preferably made with a hard material. To assist in the locking operation, a spring (9) is disposed in a cavity (31) within the clamp body (2). Preferably, the spring (9) is disposed in such manner that it biases the button (3) into a locking positions. This arrangement is especially advantageous for easy adjusting of the clamping apparatus. A user can clamp a workpiece by placing the workpiece on the table (20), pressing the button (3), lower the clamping rod (52), and release the button (3). The spring (9) then brings the button (3) into locking contact with the clamping rod (52). A user can then tighten the clamping apparatus by rotating the clamping rod (52) using the knob (4). The clamping rod (52) travels downward due to the engagement between the thread receiving portion (51) of the button (3) and the threads (50) of the clamping rod (52). Similarly, the button (3) travels upwards due to the engagement between the thread receiving portion (51) and the threads (50). This upward movement continues until the upper surface (54) of the button (3) contacts a surface (55) of the clamp body (2), securely locking the clamping rod (52) in place. The number of rotations required to lock the clamping rod (52) as described above is significantly reduced because of the preferred low pitch thread. The button and/or spring may alternatively be placed outside the clamp body, or the button may be disposed in such manner that it must be pulled out in order to unlock the clamping rod.

Claims: A clamping apparatus (10) for a power tool comprising: a clamp body (2) having a first (24) and second (25) end; an attachment member (1) having a first and second end, the first end of the attachment member connected to the first end (24) of the clamp body (2); and a threaded clamping member (52) having a first end and a second end; characterised in that the clamping member (52) is slidably connected to the second end (25) of the clamp body (2) and the clamping apparatus (10) further comprises: a button (3) moveable between an unlocking position and a locking position; and a spring (9) disposed between the clamp body (2) and the button (3) such that the spring (9) biases the button (3) into the locking position; wherein the button (3) has a thread receiving portion (51) capable of engaging the clamping member (52) and an upper surface (54) with a lip, wherein the thread receiving portion (51) is disengaged from the clamping member (52) when the button (3) is in the unlocking position and, the thread receiving portion (51) is engaged with the clamping member (52) when the button (3) is in the locking position, whereby rotation of the clamping member (52) when the button (3) is in the locking position moves the upper surface (54) of the button (3) into contact with the clamping body (2) thereby securely locking the clamping member (52) against a workpiece. A clamping apparatus (10) as claimed in claim 1, wherein the button (3) is disposed in a cavity (31) within the clamp body (2). A clamping apparatus (10) as claimed in either of claims 1 or 2, wherein the spring (9) is disposed in the cavity (31). A clamping apparatus (10) as claimed in any one of the previous claims, wherein the second end of the attachment member (1) is connectable to the power tool. A clamping apparatus (10) as claimed in any one of the previous claims, wherein the clamping member (52) comprises a pad (7) disposed at the second end of the clamping member (52). A clamping apparatus (10) as claimed in any one of the preceding claims, wherein the clamping member (52) comprises a knob (4) disposed at the first end of the clamping member (52). A clamping apparatus (10) as claimed in anyone of the preceding claims, wherein the clamping member (52) is fixedly connected to the second end (25) of the clamp body (2). A clamping apparatus (10) as claimed in any one of the preceding claims, wherein the attachment member (1) comprises a rod having a first end and a second end. A clamping apparatus (10) as claimed in claim 8, wherein the second end of the rod comprises an area of reduced diameter adapted to engage a fixing member (21) on the power tool. A clamping apparatus (10) as claimed in claim 9, the second end of the rod further comprising a partly recessed end adapted to clear the fixing member (21) of the power tool when attaching the rod. A method for clamping a workpiece on a power tool using a clamping apparatus (10) as claimed in any one of the previous claims, wherein the method comprises the steps of: placing the workpiece under the clamping member (52); pressing the button (3); lowering the clamping member (52) until the clamping member (52) contacts the workpiece; releasing the button (3), simultaneously bringing the button (3) into engagement with the clamping member (52) ; and rotating the clamping member (52) to move the upper surface (54) of the button (3) into contact with the clamping body (2) thereby securely locking the clamping member (52) against a workpiece.

Inventors: LIVINGSTON SCOTT M, PRICE SCOTT D, STUMPF WILLIAM R, LIVINGSTON, SCOTT M., PRICE, SCOTT D., STUMPF, WILLIAM R.
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1997
Main classification: B25B5
IPC codes: B25B5