Cutlery – Cutting tools – Saw
Patent
1996-01-05
1997-10-07
Payer, Hwei-Siu
Cutlery
Cutting tools
Saw
30507, B27B 2106
Patent
active
056734883
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a saw frame of the type having a bow frame with a handle at one end, and a blade extending between opposing ends of the bow frame.
In known saw frames of this type, described for example in documents U.S. Pat. No. 2,539,796, EP-A-0,022,351, GB-A356,031 and GB-A-191,105, a calibrated spring makes it possible to know the tension in the blade, but the user can exceed the maximum intended tension by a very large amount, which may prove dangerous.
SUMMARY OF THE INVENTION
The object of the invention is to provide economical and reliable means allowing a precise predetermined tension to be exerted easily on the blade, guaranteeing that this tension is not exceeded.
To this end, the subject of the invention is a saw frame of the type comprising a bow integral with a rear handle, a front member for the attachment of the distal end of a blade, this member being provided at the front end of the frame, a rear member for the attachment of the proximal end of the blade, this member being provided at the rear end of the frame, the handle being provided with a mechanism for giving the blade a limited tension, which mechanism includes a screw-nut system acted upon by a rotatable operating member, a calibrated spring being interposed between the operating member and a reaction surface of the handle, characterized in that it comprises means for stopping the rotation of the rotatable operating member after the calibrated spring has been compressed over a predetermined length in order to obtain a predetermined tension in the blade, independently of the manufacturing tolerances, and in a substantial range of hole spacings of the blade.
The saw frame according to the invention may include one or more of the characteristics described below.
The calibrated spring comprises at least one elastic washer, for example a Belleville washer.
The means for stopping the rotation of the rotatable operating member include complementary stops borne respectively by the operating member and by the frame. The complementary stop means comprise two stops designed to immobilize the operating member in a recess of conjugate shape provided in the rear end of the frame.
The maximum travel required to crush the calibrated spring is greater than the pitch of the screw-nut system. The screw-nut system comprises a slide guided in translation in a bore formed in the rear part of the frame.
The bow has a counter-curvature with its concavity facing towards the outside with respect to the blade in an intermediate part of the frame. The bow is made as a single piece and includes a rear branch incorporated into the handle. The bow comprises a tubular metallic piece. The piece has, over at least part of its length, an elongate cross-section having its larger dimension in the mid-plane of the frame. The piece is embedded in a plastic material.
A blade is held tensioned between the front member and the rear member.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will now be described with regard to the appended drawings, in which:
FIG. 1 represents a handsaw according to the invention;
FIG. 2 is a side view of part of a bow of a frame of this saw;
FIG. 3 is a section on line III--III of FIG. 2;
FIG. 4 is a partial view in perspective of the handle of the saw frame;
FIG. 5 is a partial longitudinal section of a handle showing a tensioning mechanism, an operating member not being sectioned;
FIG. 6 is a longitudinal section through the operating member of the tensioning mechanism; and
FIG. 7 is a side view of the operating member, in the direction of the arrow VII of FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a saw frame, denoted by the general reference 1, on which a blade 2 is mounted. This frame 1, which has the general shape of an inverted U with diverging branches, consists of a metal bow 3, the rear part of which is integral with a handle 4 which incorporates a tensioning mechanism 5. It will be assumed that the frame is orientated as represented, with the b
REFERENCES:
patent: 103700 (1870-05-01), Andrews
patent: 1806702 (1931-05-01), O'Neill
patent: 1949196 (1934-02-01), Youlten et al.
patent: 2539796 (1951-01-01), Shortell
patent: 3821974 (1974-07-01), Merrow
patent: 3822731 (1974-07-01), Keymer
patent: 4256156 (1981-03-01), Biszantz et al.
patent: 4376456 (1983-03-01), Jacoff
Facom
Payer Hwei-Siu
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