1. Technical Field
The present invention relates to a clamp tool in which a pair of clamping brackets is disposed on a shaft apart from each other, at least one clamping bracket can move along the shaft to fasten a workpiece in cooperation with the other clamping bracket.
2. Related Art
Such a kind of manual tool is used for coupling wood blocks to each other. For examples, U.S. Pat. No. 4,552,345 discloses a structure which includes a pair of clamping blocks disposed along a shaft, in which one clamping block moves toward the other clamping block to fasten a plurality of workpieces interposed between the pair of clamping blocks and a member for supporting the workpieces so as not to bow due to the fastening force. This structure is a typical example. On the other hand, a clamp is also known in which a pair of clamping brackets is formed to move or stop on a pipe-shaped shaft, one clamping bracket is movable with a screw mechanism, and the central axis of the screw mechanism is located at a position substantially equal to clamping portions of the pair of claming brackets. This clamp employs a gas pipe or a water pipe put on the market as the shaft. The pipe is cut in a proper length and the cut pipe is fitted with clamping tabs and necessary components. However, the screw mechanism is apart from the shaft and is always exposed due to a structural problem thereof. One of the pair of clamping brackets is directly made to move by the screw mechanism, while the other clamping bracket is not supported by the screw mechanism.
An example of the above-mentioned clamp is disclosed in U.S. Pat. No. 4,552,345. Pony clamps (product Nos. #50, #52, and #53) disclosed in URL (http//www.tamacraft.com/catalog2.html) which can be seen through an electrical communication network are also examples of the above-mentioned clamp.