Cutlery – Cutting tools – Saw
Patent
1998-05-08
2000-06-27
Rachoba, Maurina
Cutlery
Cutting tools
Saw
B27B 2106
Patent
active
060791098
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention generally relates to a frame for a metal-cutting saw of the one-piece hacksaw type including a bow extended at its rear end by a pistol grip. The pistol grip includes a hand-protection branch which meets the grip at the lower part, and which incorporates a blade-tensioning mechanism.
The user of a metal-cutting saw needs to change the blade of his tool either regularly, because the blade is becoming worn, or to change the type of blade depending on the specific type of cutting being done. All of these blade changes tend to make the blade tensioning increasingly less precise.
Metal-cutting saws having adjustable blade-tensioning devices have previously been proposed in order to solve this problem. For example, French Patent Application No. 2,624,780 discloses a device having a profiled lever with a cam shape which is capable of pushing up against and then tilting against the opposing face of the blade-holder arm. The lever is associated, via its lower part, with the outer end of a tension-retaining member, or fitting. The fitting allows the tension to be adjusted by altering the position of a nut provided on the fitting.
The disclosed device, which is relatively quick to operate, does not allow the blade to be adjusted very accurately because the position of the nut provided for achieving such adjustment can vary only by whole numbers of turns.
U.S. Pat. Nos. 4,367,779 and 4,466,471 also disclose metal-cutting saws with mechanisms for adjusting the tension of the blade using a lever in the hand grip of the saw which pivots to create tension in the blade through a rod which acts on a lever arm. In each case, the tension is adjusted by varying the length of the rod.
Although generally satisfactory, such devices are on the one hand complicated to operate, while on the other hand, because of their significant number of component parts, such devices are not very robust from a mechanical point of view.
Accordingly, it is an object of the present invention to overcome the drawbacks of these prior devices while allowing the user to preset the tension in the saw blade.
Another object of the present invention is to allow the blade to be fitted quickly, by limiting the number of operations to be carried out on the frame.
SUMMARY OF THE INVENTION
In accordance with the present invention, these and other objects are achieved by providing the frame of a metal-cutting saw of the one-piece hacksaw type with a bow which is extended at its rear end by a pistol grip having a protective branch, and which is extended at its front end by a branch which, at its end, includes an attachment stud for receiving one of the two ends of a blade. The attachment stud includes a blade-tensioning device which comprises a blade-tension adjustment system having a lever fixed by an articulation pin to an articulation stirrup piece which extends into the rear part of the protective branch. The articulation pin constitutes an axis about which the lever can rotate. The blade-tension adjustment system comprises a blade support which receives the other end of the blade and which includes an opening allowing the articulation pin to pass through, and a threaded rod which is on the one hand permanently connected to the blade support and which is on the other hand articulated to the lever by an articulation pin. The articulation pin is provided with a smooth hole through which the threaded rod can pass. A thumbwheel is screwed onto the thumbwheel, and bears against the pierced articulation pin.
The saw frame preferably includes, in combination, a hand grip, a rear branch of the bow and a stirrup piece for articulating the lever. A lower part of the grip has a shape which mates with the lever and protects the tension-adjustment members, and mates with the bow, which has a changing cross-section that curves toward the blade. Also provided is an ergonomically designed region on which the operator's thumb can rest and which is positioned on the upper branch of the bow, a region against which the blade c
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Cohen Gary M.
Goodman Charles
Rachoba Maurina
Sicfo Stanley S.A.
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