Bar clamp with arrangement for displacing a clamping jaw a large distance to securely clamp a workpiece

A bar clamp has an operating handle being in ratchet engagement with end teeth of a slide bar. The operating handle is adapted to pivot counterclockwise to cause a first clamping jaw carrier to displace along the slide bar and then pivot about a lock pin in the slide bar so as to displace a first clamping jaw a sufficiently large distance to securely clamp a workpiece by cooperating with a corresponding clamping jaw.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to bar clamps and more particularly to a bar clamp having an arrangement for displacing a clamping jaw a large distance in order to securely clamp a workpiece by cooperating with a corresponding clamping jaw.

2. Description of Related Art

A conventional eccentric clamp disclosed in U.S. Pat. No. 6,648,314 is shown inFIGS. 1 and 2. The clamp operates as below. A workpiece is preliminarily clamped between a clamping jaw of a fixed but pivotable clamping jaw carrier12and a clamping jaw of a displaceable clamping jaw carrier10. Next, counterclockwise pivot an operating handle11about 180 degrees to cause the clamping jaw carrier12to pivot a predetermined small angle so as to longitudinally displace the clamping jaw of the clamping jaw carrier12a predetermined distance as indicated by Y.

However, the patented clamp suffers from a disadvantage. In detail, the displacement distance Y is relatively small. Hence, the clamping force exerted upon the workpiece is not sufficient. It is understood that a user has to latch and unlatch the operating handle11a number of times before the workpiece can be securely clamped. Thus, a need for improvement exists.

SUMMARY OF THE INVENTION

It is therefore one object of the invention to provide a bar clamp having an arrangement for displacing a clamping jaw a large distance in order to securely clamp a workpiece by cooperating with a corresponding clamping jaw.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 3 to 6, a bar clamp in accordance with a preferred embodiment of the invention comprises the following components. Each component is discussed in detail below.

A slide bar20comprises an arcuate toothed section21on a front end, a substantially triangular channel22proximate the toothed section21, and a lengthwise elongated slot23behind the channel22.

A first clamping jaw carrier40comprises a compartment42with the slide bar20extending through, a pivot hole44aligned with the slot23, and a triangular hole43aligned with the channel22, the triangular hole43having a longitudinal surface431and a transverse surface432shown in phantom lines ofFIG. 5.

An operating handle30is hollow and comprises a pivot hole32aligned with both the hole43and the channel22, a large arcuate pressure surface31at one end engaged with a first oblique surface45of the first clamping jaw carrier40, a small arcuate pressure surface311continuous with the large arcuate pressure surface31also at one end, the small arcuate pressure surface311engaged with a joining point of the first oblique surface45and a second oblique surface451of the first clamping jaw carrier40, a pivotal release level34provided in the hollow of the operating handle30, a compression spring35anchored between an end of the operating handle30and an end of the release level34, and an intermediate ratchet member33having one end retained in a cavity341at the other end of the release level34and the other end formed with ratchet teeth which are engaged with the toothed section21.

A pin60is provided across the channel22, the triangular hole43, and the pivot hole32in order to pivotably secure the operating handle30, the slide bar20, and the first clamping jaw carrier40together.

A lock pin70is provided across the slot23and the pivot hole44in order to slidably secure the first clamping jaw carrier40to the slide bar20.

An arcuate clamping section46is formed on an end of the first clamping jaw carrier40distal the slide bar20. The clamping section46has an end461and a first clamping jaw462pivotably secured to the end461.

A second clamping jaw carrier50is provided opposite the first clamping jaw carrier40and has a compartment (not numbered) with the slide bar20extending through so that the second clamping jaw carrier50is capable of displacing along the slide bar20. The second clamping jaw carrier50has a second clamping jaw51which is also pivotably secured to its end. The second clamping jaw51is opposite the first clamping jaw462.

A clamping operation of the invention will be described in detail below. InFIG. 5, a workpiece (not shown) is preliminarily clamped between the first clamping jaw462of the displaceable pivotable first clamping jaw carrier40and the second clamping jaw51of the displaceable second clamping jaw carrier50by moving the second clamping jaw carrier50toward the first clamping jaw carrier40. Next, counterclockwise pivot the operating handle30an acute angle as indicated by an arrow shown in a phantom line to move the ratchet member33along the toothed section21. Also, the large arcuate pressure surface31exerts a pressure on the first oblique surface45of the first clamping jaw carrier40and the small arcuate pressure surface311exerts a pressure on the second oblique surface451of the first clamping jaw carrier40respectively. Hence, the triangular hole43moves downward, i.e., the longitudinal surface431thereof moving downward by engaging with the pin60. Also, the first clamping jaw carrier40moves downward relative to the slide bar20by sliding the lock pin70downward relative to and along the slot23.

InFIG. 6, further counterclockwise pivot the operating handle30another acute angle as indicated by an arrow shown in a phantom line to move the ratchet member33along the toothed section21. Also, the large arcuate pressure surface31exerts a pressure on the first oblique surface45of the first clamping jaw carrier40. The longitudinal movement of the first clamping jaw carrier40will be stopped when the lock pin70engages with the bottom end of the slot23. After stopping, the first clamping jaw carrier40immediately pivots counterclockwise about the lock pin70. Also, the transverse surface432of the triangular hole43moves leftward relative to the pin60by engaging therewith. Hence, the first clamping jaw carrier40pivots counterclockwise to cause the first clamping jaw462to displace a large distance as indicated by X. As a result, the workpiece is securely clamped. It is understood that a pressing of the release level34can disengage the ratchet member33from the toothed section21and a next clockwise pivoting of the operating handle30can return the operating handle30to its original inoperative position.