BACKGROUND AND SUMMERY OF THE INVENTION

This invention relates to saw construction, and particularly to tools used by electricians for cutting drywalls, cabinet makers, diemakers and other users. The blade is designed to cut corners in different angles in such materials as metal, glass, plastic, bone, wall board and other materials.

Prior to the present invention apparatus and methods for cutting precision angles with adjustable miter gage apparatus and methods for making precisic miter cut angles with conventional radial arm saws, table saws, band saws, router tables and other woodworking machines have been purposed. (U.S. Patent #5121554, issued in 1992.)

The prior art also discloses apparatus for changing the cutting direction in the reciprocating direction of the saw. An apparatus for connection to a reciprocating saw changes the direction in which the cutting takes place, from the reciprocating direction of the saw to a different direction. A first push rod is connected to the saw bar for linear movement in the reciprocating direction of the saw. A second push rod having a saw blade connected thereto is arranged for linear movement in a direction different than the reciprocating direction of the saw. A transmission disposed between the push rods transmits the reciprocating movement of the push rod to a corresponding reciprocating movement of the second rod, thereby imparting a cutting motion to the saw blade. The reciprocating direction of the second push rod with respect to the first push rod can be either fixed or adjustable. Optionally, the apparatus can be pivotal connected to the saw that the angular disposition of these elements with respect to one another can be adjusted. (U.S. Patent #5193281. issued in 1993.)

The two inventions are too complicated and inconvenient in practice to be easily used as hand tools.

In order to cut out a rectangular part (Fig.5 a.) from stock material, to create a workspace for joint constructions, by using the conventional saws first the material is cut along two vertical lines c-e, d-f on the length c-g and d-h correspondingly and then with the help of a drill, hammer or chisel and hammer the part between the two horizontal cuts is taken out. Later the horizontal surface e-f-k-i formed after taking out the rectangular part is processed by a file.

The present invention is directed to saw constructions wherein two identical blades, vertical and horizontal, formed by the means of folding a single blade in a desired angle, allows one to make a corner cut and/or to change the direction from vertical to horizontal. The vertical portion of the blade, at the place of folding on the teethed edge, has a gradual transition towards the horizontal portion of the blade body by gradually increasing up to the width of the body of the blade. This provides an accurate change of cut direction without taking out the saw from the cut line. The blade having teeth can be mounted in a hack-saw or it could be sharpened and attached to a handle to be used as a knife.

A main feature of the invention is a dual blade of a saw comprised of two parts having an angular disposition to each other along their length. The said angular disposition is created by means of a gradual transition of the vertical portion of the body to the horizontal portion, wherein the width of the edges forming that vertical - horizontal transmission of the blade body gradually decreases from the full width of the blade body portion to it thickness size.

Other features and advantages of the dual blade constructed according to invention, will be apparent from the attached drawings and accompanying description.

THE DRAWINGS

Fig. l is a top view of a saw according to the invention.

Fig.2 is a front view of a saw according to the invention.

Fig.3 is an unfolded plan view of a saw according to the invention

Fig.4 is perspective view of a saw according to the invention.

Fig.5 is a conventional way of cutting a rectangular piece out of the material.

Fig.6 is a perspective view of a transition portion.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

FIGS. 1, 2 and 3 represent the preferred embodiment of the saw according to our invention. FIG. 4 is intended to include cutting teeth 16 to cut any material and holes 10 and 11 are made to fasten the saw blade into the body of a hack-saw.

Referring to FIG. 3 a plan view of the saw is shown before folding it along the line 2-8. Note the two identical dividing portions 12 and 13 (as far as the blade is concerned, it is identical at both ends considering end 6 as distal end and end 1 as a proximal), wherein portion 12 has proximal end 8 and distal ends 3 and 14, and portion 13 has distal ends 2 proximal ends 5 and 9, thus making identical portions in shape. In a longitudinal section between proximal end 5 and distal end 14 the edge of the saw blade is blunt having

the thickness of the plate from which it is cut. Between proximal end 9 and distal end 3 the edge of the blade is provided with sharpened teeth according to the purpose of the blade (e.g. for cutting wood or metal). Portion 15 is formed by distal ends 2 and 7 and proximal ends 4 and 8. Points 2 and 8 form the line for folding the saw blade at the desired angle, in this case 90 degree allowing cutting for motion in vertical and horizontal surfaces. Transition section Fig. 6 provided with teeth 7-8 is formatting a curve towards to the folding line 2-8 and has smaller teeth than sections 7-3 and 8-9 for more easy transition from a vertical cutting direction into horizontal cutting direction.

Referring to FIG. 2 the section between 4-2 gradually decreases from distal end 4 to proximal end 2 towards the thickness of blade. The section from the distal end 8 to proximal end 7 gradually increases towards the width of the blade. The section from the distal end 9 to the proximal end 8 performs the function of the blade for the cutting purpose in vertical direction. The depth of the cut is limited by the hack-saw frame. The section from distal end 8 to proximal end 7 functions as a transition portion of the blade for gradually changing the direction of the cut from vertical to horizontal. This transition is performed by pushing the blade farther thus forcing the section from distal end 8 to proximate end 7. The section from distal end 7 to proximal end 3 functions to cut in a horizontal direction; here the length of the cut is unlimited.

Referring to FIG. 4 there is shown a dual blade saw during the cutting process. At first it is cutting along a vertical line using the vertical portion 13 of the blade body. Then at end of the cutting line the saw is moved farther in a forward direction so that the middle portion 15 of the blade starts to cut horizontally, until it reaches the full width of the blade body by opening enough space for the width of blade to cut. Portion 12 of the blade body cuts in the horizontal surface until the end of the marked line is reached. To finish the rectangular cut out in the material take out the blade from the cut and cut in the vertical direction above the end of the horizontal cut.