Saw Blade

Abstract

A saw blade for a hand-operated machine tool, in particular a reciprocating saw blade, includes a blade portion having a cutting edge and an opposite blade rear, in particular a cutting edge which is defined by a large number of saw teeth. The saw blade further includes a chucking shaft provided to be received by a clamping chuck of the hand-operated machine tool and a lower edge and an opposite upper edge. A transition region is constructed between the chucking shaft and the blade portion, in which a difference in spacing between the spacing of the lower edge and upper edge of the chucking shaft and the spacing between the cutting edge and the blade rear is bridged. A transition region lower edge has a raised portion, in particular a raised portion for stress relief, between the lower edge of the chucking shaft and the cutting edge.

Claims

1. A saw blade for a hand-operated machine tool, comprising: a blade portion having a cutting edge and an opposite blade rear; a chucking shaft configured to be received in a clamping chuck of the hand-operated machine tool, the chucking shaft having a lower edge and an opposite upper edge; and a transition region formed between the chucking shaft and the blade portion, the transition region bridging a difference in spacing between a first spacing defined between the lower edge and the upper edge of the chucking shaft and a second spacing defined between the cutting edge and the blade rear, the transition region including a transition region lower edge having a raised portion between the lower edge of the chucking shaft and the cutting edge of the blade portion.

2. The saw blade according to claim 1, wherein the raised portion is formed in a convex manner or as a bulge.

3. The saw blade according to claim 1, wherein the raised portion has no straight portions, steps and/or sharp edges in a longitudinal axial direction of the saw blade or the chucking shaft.

4. The saw blade according to claim 1, wherein at least portions of the transition region lower edge are defined by a spline or a polynomial line at which continuity of the pitch is prevalent.

5. The saw blade according to claim 1, wherein the transition region includes a transition region upper edge with no upper raised portion between the upper edge and the blade rear of the saw blade.

6. The saw blade according to claim 1, wherein the raised portion is not configured to be engaged round by a turnbuckle.

7. The saw blade according to claim 1, wherein a third spacing defined between the transition region lower edge and an opposite transition region upper edge is smaller at a chucking shaft side of the raised portion than at a blade portion side of the raised portion.

8. The saw blade according to claim 1, wherein a fourth spacing from a vertex of the raised portion to a rear side of the chucking shaft is from approximately 19 to 25 mm, and/or a fifth spacing from the vertex of the raised portion to the boundary point or boundary region between the transition region and the cutting edge is from approximately 5 to 10 mm.

9. The saw blade according to claim 1, wherein a radius of the raised portion in a region of the raised portion adjoining a vertex or a tip is between approximately 0.5 and 1.5 mm.

10. The saw blade according to claim 1, wherein the saw blade is configured such that stresses of the saw blade, which is loaded in terms of bending transversely relative to a blade plane, are neutralized in the transition region in a region of the transition region upper edge and the transition region lower edge which are adjacent to the raised portion in a longitudinal axial direction of the chucking shaft.

11. The saw blade according to claim 1, wherein a first boundary point between the transition region upper edge and the blade rear and a second boundary point between the transition region lower edge and the cutting edge are arranged so as to be axially offset or axially in alignment in a longitudinal axial direction of the saw blade or chucking shaft.

12. The saw blade according to claim 1, wherein the transition region lower edge and the transition region upper edge are at least substantially free from a mirror symmetry relative to the longitudinal axis of the chucking shaft.

13. The saw blade according to claim 1, wherein the raised portion acts as an actuation structure of a clamping and/or closing mechanism of a clamping chuck so as to actuate a parking position mechanism.

14. The saw blade according to claim 1, wherein a third spacing between the transition region upper edge and a longitudinal axis of the chucking shaft increases exponentially from the chucking shaft to the blade rear and/or a fourth spacing between the transition region lower edge and the longitudinal axis increases exponentially from a recess between the raised portion and the cutting edge.

15. The saw blade according to claim 1, wherein: the transition region lower edge defines a recess between the raised portion and the cutting edge, from which a third spacing to a longitudinal axis of the chucking shaft is greater than a fourth spacing between the lower edge and the longitudinal axis and is smaller than a fifth spacing between the raised portion and the longitudinal axis, and the recess extends in a longitudinal axial direction over more than 50% of the transition region lower edge and/or by a multiple of a pitch width of the saw teeth and/or over from approximately 10% to 50% of a longitudinal extent of the lower edge.

16. The saw blade according to claim 1, wherein the saw blade is a reciprocating saw blade, and the cutting edge is defined by a large number of saw teeth.

17. A hand-operated tool comprising: a saw blade, comprising: a blade portion having a cutting edge and an opposite blade rear; a chucking shaft configured to be received in a clamping chuck of the hand-operated machine tool, the chucking shaft having a lower edge and an opposite upper edge; and a transition region formed between the chucking shaft and the blade portion, the transition region bridging a difference in spacing between a first spacing defined between the lower edge and the upper edge of the chucking shaft and a second spacing defined between the cutting edge and the blade rear, the transition region including a transition region lower edge having a raised portion between the lower edge of the chucking shaft and the cutting edge of the blade portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Additional advantages will be appreciated from the following description of the drawings. An embodiment of the saw blade is illustrated in the drawings. The drawings, the description and the claims contain a number of features in combination. The person skilled in the art will advantageously also consider the features individually and combine them to form advantageous additional combinations.

[0025] In the drawings:

[0026] FIG. 1 is a schematic illustration of the saw blade according to the disclosure as a side view,

[0027] FIG. 2 is a schematic illustration of a cutout of the saw blade according to the disclosure according to FIG. 1,

[0028] FIG. 3 is a schematic illustration of another cutout of the cutout according to FIG. 2 of the saw blade according to the disclosure according to FIG. 1,

[0029] FIG. 4 is a chart for comparing bending test repetitions up to breakage of the shaft with different saw blades,

[0030] FIG. 5 shows a saw blade according to the prior art, currently marketed under the designation “Bosch S 1122 VFR Special for Pallet Repair”.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a saw blade 10 according to the disclosure for a hand-operated machine tool (not illustrated here). The saw blade 10 is a reciprocating saw blade 12 which is provided for use with a reciprocating saw (not illustrated). The reciprocating saw blade 12 is particularly provided for repairing wooden pallets or the like. A chucking shaft 14 at least substantially corresponds to a common chucking shaft 14 for reciprocating saw blades as disclosed, for example, in the current “Bosch S 1122 VFR Special for Pallet Repair Säbelsägeblätter” (reciprocating saw blades) (cf. FIG. 5) and is further widely known. In principle, however, the form and/or the configuration of the chucking shaft 14 may vary in order to cooperate with a large number of clamping chucks. By means of the chucking shaft, the saw blade 10 can be fixed to a clamping chuck or turnbuckle (not illustrated here), in particular to an SDS of a hacksaw, in particular a reciprocating saw. The saw blade 10 has a blade portion 16 having a cutting edge 18 or front edge or working edge. The cutting edge 18 has a large number of saw teeth 22. The cutting edge 18 and/or the saw teeth 22 which define the cutting edge 18 in this case may take up a large number of different forms, profiles and/or teeth or pitch patterns which are suitable for carrying out a large number of cutting operations, including, but not limited to, cutting wood, metal, plastics material and/or other materials. The reciprocating saw blade 12 is particularly preferably suitable for severing wooden and metal materials, in particular for repairing pallets. The chucking shaft 14, a transition region 38 and the blade portion 16 are advantageously constructed or formed in one piece but may be constructed, configured or formed in a number of different, known or as yet unknown manners.

[0032] Opposite the cutting edge 18, the blade portion 16 has a blade rear 20 or a rear or a non-cutting edge. This blade rear/edge is arranged here with a defined, in particular constant, spacing from the cutting edge 18. In principle, however, the form and the configuration of the blade rear 20 may vary, for example, the blade rear 20 may also be constructed as a cutting edge, it may be constructed at an angle, in an undulating manner and/or with variable spacing from the cutting edge 18, or the like. According to FIG. 1, the cutting edge 18 and the blade rear 20 are orientated substantially along or parallel with a longitudinal axis 24 of the blade portion 16, that is to say, here in particular orientated parallel with each other. The blade portion 16 terminates at the front with a tip 26. The tip 26 can also take up a large number of known or as yet unknown forms.

[0033] In particular, the saw blade 10 is constructed in a relatively flexible manner and has to this end a relatively small blade thickness of a maximum of 1.3 mm, in particular from 0.7 to 1.1 mm, preferably approximately 0.9 mm. This thickness advantageously corresponds to the thickness of the chucking shaft 14, of the transition region 38 and of the blade portion 16. In particular, the cutting edge 18 has a cutting edge width, which is formed, for example, by setting the saw teeth 22 or the like, of a maximum of 1.7 mm, in particular from 1.1 to 1.5 mm, preferably approximately from 1.3 to 1.4 mm. Advantageously, therefore, the blade portion 16, the transition region 38 and the chucking shaft 14 are constructed with the same thickness. The saw blade 10 is therefore constructed to be relatively thin in comparison with other reciprocating saw blades for other applications so that the saw blade 10 is relatively flexible or pliable transversely to the wide sides 28 of the saw blade 10 or transversely to a blade plane (not illustrated) which is defined by the longitudinal axis 24 and a connection axle 30 which extends transversely to the longitudinal axis 24 through the cutting edge 18 and the blade rear 20.

[0034] The chucking shaft 14 is provided to be received by a clamping chuck of the hand-operated machine tool. It has a lower edge 34 and an opposite upper edge 36. The lower edge 34 is arranged on the saw blade side of the cutting edge 18 or the front side and the upper edge 36 is arranged on the saw blade side of the blade rear 20 or the rear side. The transition region 38 is constructed between the chucking shaft 14 and the blade portion 16. In this case, particularly along a longitudinal axis 25 of the chucking shaft 14 or the longitudinal axis 24 of the blade portion 16, a spacing changes between a transition region lower edge 48 and transition region upper edge 50. A spacing difference between the spacing 40 of the lower and upper edges 34, 36 of the chucking shaft 14 (cf., for example, between point H and J) and a spacing 42 between the cutting edge 18 and the blade rear 20 can thus be bridged in particular without any sharp corners, edges and/or tight radii. The transition region 38 bridges in a manner of speaking a difference in width between a width of the chucking shaft 14 and a width of the blade portion 16. The transition region 36 is in a manner of speaking adapted, on the one hand, to the width 40 of the chucking shaft 14 and, on the other hand, to the width 42 of the blade portion 16. A difference in width between the chucking shaft 14 and the blade portion 16 can thereby be bridged. The opposite lower and upper edges 34, 36 of the chucking shaft 14 are constructed substantially parallel with each other at least in portions, in particular substantially in a region between the transition region 38 and an additional transition region 44 to a cam 46 of the chucking shaft 14. They can thereby be positioned with relatively little play in the clamping chuck. In known manner, a hole 32 is arranged in the chucking shaft 14 besides the cam 46. The hole 32 acts in known manner as an auxiliary positioning means and/or clamping means for a clamping bolt or pin of the turnbuckle of the hand-operated machine tool. The cam 46 extends the lower edge 34 in known manner in order, for example, to distribute the forces which occur during sawing over a greater abutment face in the turnbuckle. In particular, the cam 46 or the upper edge 36 may also have inclined faces, chamfers or rounded portions in order, for example, to make introduction of the saw blade 10 into the turnbuckle easier. The chucking shaft 14 can also take up other known or as yet unknown configurations.

[0035] According to the disclosure, a transition region lower edge 48 has between the lower edge 34 of the chucking shaft 14 and the cutting edge 18 of the blade portion 16 a raised portion 52, in particular a stress-relieving raised portion. The raised portion is constructed in a convex manner or curved radially outwardly. It is in a manner of speaking constructed as a bulge. The raised portion 52 has in a manner of speaking a raised curvature or rounding. This projects at least when viewed in the longitudinal axial direction 25 of the chucking shaft 14 at both sides beyond a notional extension line of the lower edge 34 and/or beyond the adjoining regions of the transition region lower edge 48. The raised portion 52 rises or is delimited in a manner of speaking in the longitudinal axial direction 25 from the adjoining regions. The raised portion 52 has a particularly rounded tip. The raised portion 52 is free from in particular sharp edges, in particular in the longitudinal axial direction 24 of the saw blade 10 or longitudinal axial direction 24, 25 of the blade portion 16 or chucking shaft 14. Undesirable accumulations of stresses can thereby be avoided, in particular bending stress accumulations in the transition region 38 or boundary region between the chucking shaft 14 and blade portion 16 to the transition region 38.

[0036] The raised portion 52 is constructed to be at least substantially free from straight portions, steps and/or sharp edges in the longitudinal axial direction 24, 25 of the saw blade 10 or the chucking shaft 14. Stress peaks in the transition region 38 can also thereby be avoided. A distribution of stresses in the end portion 54 of the saw blade 10 in a saw blade 10 which is loaded in terms of lateral bending (transversely relative to the wide side 28), in particular in the central transition region 38, is substantially homogeneous and therefore of the same size, in particular also in significant portions of the transition region upper and lower edges.

[0037] From FIG. 3, which illustrates an enlarged view of the region 62 from FIG. 2 which in turn illustrates an enlargement of the region 64 of FIG. 1, the transition region lower edge 48, in particular the contour thereof, is defined in the longitudinal axial direction 25 of the chucking shaft 14 by a spline or a polynomial line 66. A large number of points B, C, D, E, F at which continuity of the pitch is applied define this polynomial line 66. The points B and C and the points E and F are arranged with spacing relatively near each other in comparison with the points C, D and E. The transition region lower edge 48 thereby forms between the points C, D and E a basin-like recess. However, in the points F and B of the transition region lower edge 48 a relatively high pitch is provided relative to the longitudinal axis of the chucking shaft 14. In the region of the point G, the raised portion 52 forms a vertex or the tip. The raised portion 52 has a radius of curvature R1. The transition region lower edge contour 48 finally merges with a radius R3 at the point H into the lower edge of the chucking shaft 14. Conversely, it merges at the point A into the cutting edge 18 or directly here into the first or last saw tooth 68 of the cutting edge 18. A radius R2 is provided between the point A and B. The points A and B have a greater spacing H.sub.A, H.sub.B than the points C to H relative to the longitudinal axis 25 of the chucking shaft 14 or a notional extension line 70 of the lower edge 34 (which is constructed parallel with the longitudinal axis 25) of the chucking shaft 14. The point C has a slightly smaller spacing H.sub.C relative to the longitudinal axis 25 of the chucking shaft 14 or the notional extension line 70 of the lower edge 34 than the spacing H.sub.G of the point G which marks the vertex of the raised portion. The points D, E, F of the transition region lower edge 48 all have a smaller spacing H.sub.D, H.sub.E, H.sub.F relative to the longitudinal axis 25 of the chucking shaft 14 or a notional extension line 70 of the lower edge 34 than at least the point G of the raised portion 52. The point H is arranged on the notional extension line 70 of the lower edge 34 and therefore has no spacing H.sub.H therefrom or alternatively the smallest spacing from the longitudinal axis 25 of the chucking shaft 14.

[0038] At a transition region upper edge, cf. FIG. 1 or 2, however, no raised portion is arranged between the upper edge 36 and the blade rear 20 of the saw blade 10. In principle, however, a raised portion, in particular with a similar or analogue form (curved, convex) to the raised portion 52, can also be constructed in this instance on the transition region lower edge, this may be advantageous particularly if the blade rear 20 of the saw blade 10 also had saw teeth. The raised portion 52 is not provided to be engaged round by a turnbuckle, in particular not engaged round in a positive-locking manner, as known, for example, from T-shaped shafts of jigsaw blades and the associated turnbuckles thereof. A minimum spacing A.sub.U, A.sub.O between the transition region lower edge 48 and the opposite transition region upper edge 50 (cf. FIG. 2) is smaller at the chucking shaft side 100 of the raised portion 52 than at the blade portion side 102 of the raised portion 52. The term “chucking shaft side 100” or “blade portion side 102” is intended to be understood to mean the side facing the chucking shaft 14 or the blade portion 16 from the raised portion 52 in the longitudinal axial direction 25 of the chucking shaft 14. A spacing 72, in particular of a vertex (point G) of the raised portion 52 from a rear side 74 or end side of the chucking shaft 14 is in the longitudinal axial direction 25 of the chucking shaft 14 approximately from 19 to 25 mm, in particular from 21 to 22 mm. A spacing 76, in particular of a vertex (point g) of the raised portion 52 from the boundary point 78 (point A) of the transition region 38 to the cutting edge 18 is approximately from 5 to 10 mm, in particular from 7 to 9 mm. In total, a spacing from the rear side 74 of the chucking shaft 14 as far as the boundary point 78 (point A) is approximately from 25 to 35 mm, in particular approximately 30 mm. A spacing 88 of the hole from the rear side 74 is approximately from 11 to 11.5 mm. These dimensions may deviate depending on the configuration of the saw blade 10, in particular of the chucking shaft, transition region and blade portion.

[0039] A boundary point 80, K, K′ between the transition region upper edge 50, 50′ and the blade rear 20 and the boundary point 78, A between the transition region lower edge 48 and cutting edge 18 are arranged so as to be axially offset from each other in the longitudinal axial direction 24, 25 of the saw blade 10 or chucking shaft 14. However, they can also be arranged approximately in alignment (cf. broken line 50″ and boundary point K″). The transition region lower edge 48 and transition region upper edge 50 are constructed in the present embodiment to be at least substantially free from symmetries relative to each other, in particular free from a mirror symmetry relative to the longitudinal axis 25 of the chucking shaft 14. In principle, the transition region 38 can also be constructed to be sand-blasted or to have other means for improving the stability under loading.

[0040] Furthermore, the raised portion 52 acts as an actuation means of a clamping and/or closing mechanism of a clamping chuck (not illustrated here), in particular of an SDS of a hand-operated machine tool. The side 82 of the raised portion 52 facing the chucking shaft 14 may be used in particular as an actuation means of a parking position mechanism of an SDS.

[0041] A spacing from the longitudinal axis 25 of the chucking shaft 14 of the transition region upper edge 50 increases from the chucking shaft 14 to the blade rear 20, in particular exponentially. It increases as far as the blade rear by approximately 2.5 mm. Similarly, a spacing of the transition region lower edge 48 increases from a recess 84 between the raised portion 52 and the cutting edge 18, in particular exponentially.

[0042] The transition region lower edge 48 has the recess 84 between the raised portion 52 and the cutting edge 18. It is constructed in a substantially basin-like manner, in particular between the points C, D and E. The recess 84 has in particular a spacing from the longitudinal axis 25 of the chucking shaft 14 which is greater than a spacing of the lower edge 34 from the longitudinal axis 25 of the chucking shaft 14 and smaller than a spacing of the raised portion 52 from the longitudinal axis 25. FIG. 3 illustrates only the spacing from the extension line 70 of the lower edge 34 which extends parallel with the longitudinal axis 25, however. The recess extends in a longitudinal axial direction 25 of the chucking shaft over more than 50%, in particular approximately from 50 to 75% of the transition region lower edge 48 and/or by a multiple pitch width P of the saw teeth 22 and/or over approximately from 10 to 50% of the longitudinal extent 86 of the lower edge 34. Advantageously, the spacing H.sub.G is approximately from 1 to 1.5, in particular approximately from 1.1 to 1.25 mm, the spacing H.sub.F is approximately from 0.9 to 1 mm, the spacing H.sub.E is approximately from 0.4 to 0.5 mm, the spacing H.sub.D is approximately from 0.3 to 0.4 mm, the spacing H.sub.C is approximately from 1.1 to 1.2 mm and/or the spacing H.sub.B is approximately from 1.7 to 2.0 mm. A shaft angle 90 of the chucking shaft 14 relative to the longitudinal axis of the blade portion is approximately 3°. However, the spacings H.sub.A-H.sub.G and the shaft angle 90 may vary. For example, values from 0 to 10° are conceivable as shaft angles.

[0043] FIG. 4 illustrates the result of tests with different saw blades for repairing panels. A relative number of cycles, at which a blade tip of the saw blades which are clamped in a hand-operated machine tool has been displaced transversely relative to the blade plane until the shaft broke is indicated on the ordinate. On the left on the abscissa, the number of cycles 92 of a comparison reciprocating saw blade (as depicted in FIG. 5) without any raised portion and without any sand-blasting is indicated after the shaft broke. At the center, a number of cycles 94 of a saw blade, which is based on the comparison saw blade (as depicted in FIG. 5) and the shaft and transition region of which have been sand-blasted, is indicated after the shaft broke. On the right, the number of cycles 96 after which the shaft broke in a saw blade 10 according to the disclosure which has a raised portion 62 according to the disclosure is indicated. This explains that the saw blade 10 according to the disclosure, preferably being used for repairing pallets, has a substantially increased service-life, in particular a service-life which could even significantly exceed that of a sand-blasted saw blade according to the prior art.