Foldable saw

Abstract: In a folding saw in which either the edge of the blade, the handle or both are curved, to prevent the edge of the blade from being exposed when blade is folded so that the saw can be handled safely. (Means of solution) A protective cover (4) in which the edge (1a) of the blade (1) can be nestled is placed inside the housing groove (3) of the handle (2) having a semi-U-shaped cross section for housing the blade (1) in such a way that it is pivotally revolvable around the top end of the handle. A revolvable control lever (5) is established at the bottom end of the handle (2), and a portion of the control lever (5) is engaged with the tip of the protective cover (4). The protective cover (4) can be retracted into and pulled out of the housing groove (3) of the handle (2) by the revolving operation of the control lever (5). In this way, the protective cover (4) covers the edge (1a) of the blade (1) that is exposed from the housing groove (3).

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a hand saw that can be folded into a handle (hereinafter referred to as a "folding saw"). This is a saw in which the blade is pivotally attached by its base end to the top end of a handle having a U-shaped cross section and can be revolved to be folded into the handle when not in use. Such saws are in widespread use as a pruning saw, a gardening saw or as a crafting saw. PRIOR ART A conventional folding saw has a straight blade pivotally attached by its base end to the top end of a straight handle. When the blade is folded into the handle, the edge is completely housed within the handle. Recently, however, as shown in FIG. 11 (a), saws, in particular pruning saws, having a blade A with a concavely curved edge B and a handle C that are pivotally supported by a pivot D, have come into widespread use. Such saws having a concavely curved blade edge are generally called curved saws. A curved saw is less likely to disengage from the object to be cut, and is therefore capable of cutting the object more effectively. Accordingly, a folding saw having a blade A with a concavely curved edge B housed in a handle C, which is also concave in the same direction as the edge B, as shown in FIG. 11, has been developed. Other variations of the folding saw include those having a blade A with a concave edge B and a straight handle A. This applicant has previously invented a folding saw featuring a retractable protective cover housed inside the housing groove of the handle C, in which when the blade A is folded, the protective cover projects out of the handle so as to cover the edge B of the blade exposing from the housing (Japanese Patent Application 2000-110794). PROBLEMS TO BE SOLVED BY THE INVENTION A folding saw combining a concavely curved edge and a straight handle has a mildly curved form when unfolded as shown in FIG. 11 (a). When the blade is folded, however, a portion of the edge, in particular, the middle portion of the curved edge, is exposed as shown in FIG. 11 (b). The degree of the exposure differs according to the curvature and overall length of the blade. The exposed portion E poses a danger because it can injure a finger of the saw handler or damage an object while the folding saw is being carried or stored. The edge B itself can also be damaged by another object that accidentally comes into contact with it. The Japanese Patent Application 2000-110794, which was invented by this applicant, solves the problems associated with the conventional technique described above by introducing a protective cover that protects the exposed edge part of the blade. The present invention simplifies the construction of the folding knife proposed in the above application and makes it even easier to use. MEANS FOR SOLVING THE PROBLEMS To achieve the objective mentioned above, the present invention introduces a protective cover that can be pulled out or pushed into the housing groove of the handle for housing the blade. The protective cover is pivotally revolvable around the top end of the handle. At the bottom end of the handle, a control lever is provided. A portion of the control lever is engaged with the top end of the protective cover. The protective cover can be retracted into and pulled out of the housing groove of the handle by revolving the control lever. In this way, when the blade is folded, the protective cover housed in the housing groove 3 is pushed out of the housing groove so as to cover the edge of the blade exposed from the housing groove. The control lever at the bottom end of the handle is revolvably attached to the bottom of the handle inside the housing groove via a pivot, which crosses the plane of the blade at a right angle. A portion of the protective cover is held loosely in a concave part formed at one end of the control lever, and an operating part, which is a portion of the control lever, sticks out of the periphery of the handle. At this time, it is convenient to form a concave groove at a portion of the control lever, and the top end of the blade is inserted into the concave groove when folded. Effects of the Invention According to the folding saw of the invention described in claim 1, in which either the edge of the blade, the handle or both are curved in a concave shape, the edge part that is exposed from the housing groove of the handle when the blade is folded is covered by a protective cover. A folding saw equipped with such a protective cover is safe because the edge of the blade does injure the operator while being carried. In addition to protecting the operator, this folding saw has the effect of preventing the edge from accidentally coming into contact with and damaging other objects or, conversely, being damaged by such contact. According to the invention described in claim 2, the control lever for controlling the protective cover and the protective cover are firmly engaged with each other, avoiding the situation in which the folding saw cannot be operated or the control lever itself obstructs the cutting operation. According to the invention described in claim 3, the blade can be folded to the part where the control lever is arranged, so the handle need not be extended in order to incorporate the control lever. By having the control lever hold the tip of the blade, the folded blade can be held firmly and stably. PREFERRED EMBODIMENTS OF THE INVENTION Preferred embodiments of the present invention will now be described by reference to the accompanying drawings. Brief Description of the Drawings FIG. 1 is a longitudinal section view of a folding saw of the present invention, in which the blade of the saw is unfolded. FIG. 2 is a side view in which the blade is folded and the protective cover is housed inside the housing groove. FIG. 3 is a side view in which the blade is folded and the protective cover is projected from the housing groove. FIG. 4 is a longitudinal section view of the condition shown in FIG. 2. FIG. 5 is a longitudinal section view of the condition shown in FIG. 3. FIG. 6 is an enlarged section view of the bottom part of the handle in the condition shown in FIG. 2. FIG. 7 is an enlarged section view of the bottom part of the handle in the condition shown in FIG. 3. FIG. 8(a) is a cross section view of the middle part of the folding saw in the condition shown in FIG. 2. FIG. 8(b) is a cross section view of the middle part of the folding saw in the condition shown in FIG. 3. FIG. 9 is a perspective view of the protective cover. FIG. 10 is a perspective view of the control lever. FIG. 11 is a front view of an example of a conventional folding saw. In the embodiments shown in FIGS. 1 to 10, a concavely curved blade 1 is pivotally supported by a pivot 9 at the top end of a concavely curved handle 2. When the blade 1 is revolved and folded, the edge 1a of the blade 1 is housed within the housing groove 3 of the handle 2 having a semi-U-shaped cross section. At the base end of the blade 1, two cuts 10, 11 are formed on the circular arc centered on the pivot 9. A stopper 12 is provided on the handle 2. The stopper 12 engages the cuts 10, 11 to hold the blade 1 in a ready-to-cut condition as shown in FIG. 1 and in a folded condition as shown in FIGs. 2 to 5. The stopper 12 is pivotally supported by a pivot 13 and energized by a spring 14 in such a direction that a claw 15 at its tip engages the cut 10 or 11, so that the claw 15 maintains its engagement with the cut 10 or 11. This foldable saw can be carried, stored or otherwise handled with its blade folded. Inside the housing groove 3 of the handle 2 having a semi-U-shaped cross section, a protective cover 4 having a semi-U-shaped cross section and capable of housing the edge 1a of the blade 1 within its own groove 4a from the open side is provided as shown in FIG. 8. The protective cover 4 revolves around the pivot 16 located at the top end of the handle 2 within the housing groove 3, and can be retracted into or pulled out of the housing groove 3 of the handle 2. At the bottom end of the handle inside the housing groove 3 of the handle 2, a control lever 5 for manually retracting the protective cover 4 into or pulling it out of the housing groove 3 is provided. The control lever 5 at the bottom end of the handle 2 is revolvably attached to the bottom end of the handle inside the housing groove 3 via a pivot 6, which crosses the plane of the blade 1 at a right angle. At the top end of the revolvably attached control lever 5, a concave part 7, which is depicted as a rounded cut in the drawings, is formed. A portion of the protective cover 4 is held loosely in the concave part 7, and an operating part 5a, which is a portion of the control lever 5, sticks out of the periphery of the handle. As shown in FIG. 10, the control lever 5 is provided with a concave groove 8 on the side on which the blade 1 is folded, so that when the blade 1 is folded, the top end of the blade goes into the concave groove 8. It is of course possible to use a blade 1 that does not reach the control lever 5 and not to form the concave groove 8. However, by allowing the top end of the blade to enter the concave groove 8 of the control lever 5, it is possible to use the portion where the control lever 5 is provided as an extension of the housing for the blade, therefore it is possible to house a long blade 1. In FIG. 10, numeral 17 refers to a throughhole for the pivot 6. The folding saw described in the drawings operates as follows. When the blade 1 is revolved around the top end of the handle 2 so that it is ready to cut as shown in FIG. 1, the claw 15 of the stopper 12 provided at the top end of the handle 2 engages with the cut 10 formed at the base end of the blade 1. At this time, the resiliency of the spring 14 works to maintain the engagement, and the protective cover 4 arranged inside the housing groove 3 is revolved by the control lever 5 into the housing groove 3 of the handle 2 so that it does not project out of the profile of the handle 2. In order to maintain the control lever 5 at a certain position, for example, at the position shown in FIG. 1 at which the protective cover 4 is revolved counter-clockwise so as to remain inside the housing groove 3, or in the condition shown in FIG. 3 in which the protective cover 4 is revolved clockwise so as to project from the housing groove 3, a convex part is formed on either the surface of the control lever 5 or the inside of the housing groove 3 of the handle 2 and a concave part is formed on the other of the two, and the convex part and the concave part are meshed with each other. As an example, as shown in FIG. 10, a small projection 20 is formed on the side of the control lever 5, and two concave grooves 21, 22 are engraved inside the housing groove 3 of the handle 2. The concave groove 21 engages the small projection 20 at the position at which the protective cover is maintained inside the housing groove 3 as shown in FIG. 4. The concave groove 22 engages the small projection 2 at the position at which the protective cover 4 projects from the housing groove 3 as shown in FIG. 5. In this way, the control lever 5 can be maintained at a certain position. When the control lever 5 is operated with a little force, the small projection 20 is easily disengaged from the concave groove 21 or 22. The concave grooves 21, 22 may be formed as round concavities, but the same effect can be obtained easily by forming grooves that lead to the open end. This kind of mechanism is commonly known as a click mechanism. From the condition shown in FIG. 1, the bottom end of the stopper 12 can be pressed to raise the claw 15 against the resiliency of the spring 14, thereby disengaging the stopper 12 from the cut 10. Then the blade 1 can be revolved and folded as shown in FIGS. 2 to 5. When the blade 1 is revolved and folded, the top end of the blade 1 goes into the concave groove 8 of the control lever 5 to the extent that the blade 1 cannot be revolved any more as shown in FIGS. 2 and 4. At this time, because the handle 2 and the blade 1 are both curved, a rather large gap 18 is formed between the handle 2 and the blade 1 as shown in FIGS. 2 and 4. In this condition, the edge 1a of the blade 1 is exposed, and it is dangerous to carry the saw in this condition. In order to safely carry the saw with the blade 1 folded, the operating part 5a that sticks out from the bottom end of the handle 2 in FIG. 2 is revolved clockwise as viewed from this side. Then the protective cover axially attached to the top end of the handle 2 via the pivot 16 revolves and appears from the housing groove of the handle 2 to the gap 18 as shown in FIG. 3. In this way, a portion of the handle 1, specifically the edge 1a, goes into the concave groove 4a of the protective cover 4 and protected. The shape of the protective cover 4 and the depth of the concave groove 4a need not be such that the teeth of the blade 1 are completely covered. As long as the gap is small enough so that the top ends of the teeth do not come into contact with the operator's fingers, the edge 1a of the blade 1 may be exposed partially without causing any problem. When the blade 1 is unfolded and in a ready-to-cut condition, the operator grabs the handle 2 to use the saw. At this time, if the protective cover 4 remains projected from the housing groove of the handle 2, it is not easy for the operator to work. To lessen this inconvenience, when unfolding the blade 1, or when the blade 1 is unfolded and in the ready-to-cut condition, the operator can turn the operating part 5a of the control lever 5 counter-clockwise as indicated by an arrow in FIG. 3, and house it inside the housing groove 3 of the handle 2. In this way, the protective cover 4 does not pose an obstacle when performing a cutting operation while grabbing the handle 2. The control lever 5 itself, which controls the movement of the protective cover 4, does not obstruct the cutting operation because it is positioned at the bottom end of the handle 2 and the operating part 5a only sticks out from the periphery of the handle 2. The protective cover 4, an end of which is axially supported by the pivot 16, engages with a portion of the control lever 5, which is revolvably attached via the pivot 6, so that the protective cover 4 can be operated by operating the control lever 5. The engagement can be achieved in a variety of constructions. In the embodiment shown in the drawings, a round concave part 7 is formed at one end of the control lever 5 and is loosely engaged with and maintained by the corresponding end of the protective cover 4, which is also formed round. In this way, the protective cover 4 and the control lever 4 can remain engaged, while their smooth operation is guaranteed. Specifically, by making the thickness of the protective cover 4 about the same as the thickness of the control lever 5 as well as the width of the housing groove 3 of the handle 2 such that the protective cover 4 is revolvable, the blade 1 does not move unnecessarily inside the housing groove 3. The control lever 5 revolves around the pivot 6. At the other end of the control lever 5, i.e., on the open side of the housing groove 3 with reference to the pivot 6, a concave groove 8 into which the tip of the blade is inserted, is formed. Because the control lever 5 functions as a part of the handle of the folding saw, the handle 2 itself need not be unnecessarily long. Because the concave groove 8 of the control lever 5 is formed within the range of the thickness of the control lever 5, which is housed inside the housing groove 3, the width of the concave groove 8 is relatively narrow. This makes it possible to maintain the blade 1 inside the concave groove 8 in a stable condition with little play. The width of the concave groove 8 is preferably about the same as the width of the concave groove 4a of the protective cover 4. In addition, in the embodiment shown in the drawings, the handle 2 itself is formed in one piece with a synthetic resin material and provided with non-slip rubber 19 that covers the part of the surface of the handle that is likely to be gripped by hand, specifically the part that extends from the middle to the bottom end of the handle. The non-slip rubber 19 can be formed integrally with the handle 2 by inserting one into the other.

Claims: A folding saw comprising a blade (1) and a handle (2), in which either the edge (1a) of the blade (1), the handle (2) or both are curved in a concave shape towards the edge side, and the base end of the blade (1) is pivotally attached to the top end of the handle (2) having a semi-U-shaped cross section so that the blade (1) can be revolved in such a way that at least a portion of the edge (1a) of the blade (1) is housed in the U-shaped housing groove (3) of the handle (2), characterized in that a protective cover (4), which is pivotally revolvable around the top end of the handle, is housed inside the housing groove (3) of the handle (2) for housing the blade (1), a revolvable control lever (5) is established at the bottom end of the handle (2), a portion of said control lever (5) is engaged with the top end of the protective cover (4), said protective cover (4) can be retracted into and pulled out of the housing groove (3) of the handle (2) by revolving the control lever (5), and when the blade (1) is folded, the protective cover (4) sticks out of the housing groove (3) of the handle (2) so as to cover the portion of the edge (1a) of the blade (1) that is exposed from the housing groove (3). A folding saw as claimed in claim 1, in which the control lever (5) at the bottom end of the handle (2) is revolvably attached to the bottom of the handle inside the housing groove (3) via a pivot (6), which crosses the plane of the blade (1) at a right angle, a portion of the protective cover (4) is held loosely in a concave part (7) formed at one end of the control lever (5), and an operating part (5a), which is a portion of the control lever (5), sticks out of the periphery of the handle. A folding as claimed in claim 2, in which a concave groove (8) is provided at a portion of the control lever (5) at the bottom end of the handle (2) inside the housing groove (3), and the top end of the blade (1) is inserted into the concave groove (8) when folded.

Inventors: KANZAWA KUNIYUKI, Kanzawa Kuniyuki c/o Kanzawa Seiko Co., Ltd.
Applicants: KANZAWA SEIKO CO LTD, KANZAWA SEIKO CO., LTD
Application year: 2001
Main classification: B23D51
IPC codes: B27B21, B23D51, B27G19