This application is a 35 U.S.C. § 371 National Stage Application of PCT/EP2017/082064, filed on Dec. 8, 2017, which claims the benefit of priority to Serial No. DE 10 2017 203 031.3, filed on Feb. 24, 2017 in Germany, the disclosures of which are incorporated herein by reference in their entirety.

BACKGROUND

The disclosure relates to a reciprocating saw blade for a power tool such as, for example, a jigsaw blade or saber saw blade.

Such a reciprocating saw blade is known from DE 10 2007 039 240 A1. The reciprocating saw blade, in the form of a jigsaw blade, has a first and a second row of saw teeth, which are arranged at an angle to each other. Both the first and the second row of saw teeth are at an angle with relative to the stroke axis, or longitudinal axis, of the reciprocating saw blade, the angle of the first row of saw teeth being oriented oppositely to the angle of the second row of saw teeth.

SUMMARY

The disclosure is based on a reciprocating saw blade for a power tool, in particular a jigsaw blade. The reciprocating saw blade has a first row of saw teeth and a second row of saw teeth, wherein the first and second row of saw teeth are at an angle with respect to a longitudinal axis, or stroke axis, of the reciprocating saw blade. The angle of the first row of saw teeth is oriented oppositely to the angle of the second row of saw teeth.

It is proposed that a further row of saw teeth be arranged between the first and second row of saw teeth. The further row of saw teeth is set back, in particular set back in a stepwise manner, toward the longitudinal axis relative to the first and second row of saw teeth. Thus, in the direction of the longitudinal axis, or stroke axis, of the saw blade, the saw blade has at least three saw teeth portions. The longitudinal axis extends between the shank and the tip of the saw blade, and runs at least centrally through the shank. The sequence of the saw teeth portions, in the direction of the longitudinal axis of the saw blade, starting from the shank, to the tip of the reciprocating saw blade, is preferably as follows: firstly, the first row of saw teeth, followed by the further row of saw teeth, and then finally the second row of saw teeth. The first, second and further row of saw teeth each have saw teeth having saw-tooth tips. The saw-tooth tips of the further row of saw teeth are thus set back, in particular set back in a stepwise manner, from the saw-tooth tips of the first and second row of saw teeth, with respect to the longitudinal axis. The distance of the saw-tooth tips of the further row of saw teeth from the longitudinal axis of the reciprocating saw blade is thus less than the least distance of at least one saw-tooth tip of the first and second row of saw teeth. The longitudinal axis, or stroke axis, of the saw blade is deliberately selected here as a reference quantity, since a back of the saw blade may in part run obliquely in relation to the longitudinal axis of the saw blade. In principle, however, the set-back may also be referred to as an offset toward the back of the saw blade, in particular when the back of the saw blade is also oriented parallel to the direction of the stroke axis. Owing to the set-back, further row of saw teeth, when the reciprocating saw blade is being used for sawing, upon transition from the first or second row of saw teeth to the further row of saw teeth (during an upward and/or downward stroke), in particular in an abrupt manner, the material removal volume is reduced (with otherwise constant parameters, such as: constant stroke rate, constant guide motion of the reciprocating saw over the workpiece in the sawing direction, constant workpiece parameters). In addition, the receiving volume for sawdust is increased in the region of the further row of saw teeth (chip space is increased). It is advantageous advantageous, however, to render possible at least a reduced removal of material, or sawing, in the region of the further row of saw teeth (see further below), in particular by the choice of the magnitude, or distance, of the set-back of the further row of saw teeth from the longitudinal axis in relation to the distance of the adjacent first and second rows of saw teeth from the longitudinal axis. Moreover, the set-back, in particular the change in material-removal volume resulting therefrom, is effected in a region of the reversal point of the stroke movement (upper and lower dead point) that is important for the quality of cut. This is to be illustrated using the example of a jigsaw performing work on a wooden workpiece. Relative to a workpiece surface on which the handheld power tool is supported, via the foot plate, the reciprocating saw blade is in an upward or return movement toward the handheld power tool. The saw teeth of the second row of saw teeth cut and/or detach and/or tear sawdust, in particular intensified by the angular (positive) broaching position (angle of the second row of saw teeth in relation to the longitudinal axis) from the lower workpiece surface into the workpiece. The saw teeth of the first row of saw teeth (which, as described further below, has, in particular, saw teeth oriented toward the tip of the saw blade) that has an angular (negative) broaching position relative to the upward movement (cf. angle of the first row of saw teeth in relation to the longitudinal axis, or, in other words, the distance of the first saw teeth of the first row of saw teeth from the longitudinal axis decreases, starting from the shank, toward the further row of saw teeth), cut and/or detach and/or tear at least hardly any sawdust from the upper surface facing toward the power tool (but do transport already detached sawdust from this surface; key word, chip removal). Owing to the, in particular, step-wise set-back of the further row of saw teeth, cutting and/or detaching and/or tearing of sawdust is additionally avoided, or at least reduced. Moreover, the set back additionally reduces tears at the surface, facing toward the power tool, of a, for example, thinner workpiece. In the case of thinner workpieces, the saw blade can be drawn out of the workpiece (in the region of the upper dead point, or reversal point), to beyond a dividing plane of the saw blade, such that a region of the further row of saw teeth, having saw teeth that (on a side of a dividing of the saw blade that faces toward the tip) are oriented toward the shank, can come into contact with the upper workpiece surface. Owing to the set-back, however, the cutting, detaching and/or tearing effect is reduced, such that, even in the case of thin workpieces, tears can be reduced. Altogether, the quality of cut can thus be improved. The number and severity of unwanted, so-called workpiece tears, in particular at the workpiece surface (both at the upper and the lower workpiece surface) is reduced.

Scrappage of material can be avoided, and sawing from underneath, or from opposite the visible surface (as often used by professionals when sawing with jigsaws, to circumvent the problem) can be avoided. This improves the handling, or working, of workpieces with the saw blade according to the disclosure, and renders the working process more pleasant and convenient.

Further, it is proposed that the further row of saw teeth be arranged on a straight line, in particular on a straight line parallel to the longitudinal axis. The saw teeth, in particular the saw-tooth tips of the saw teeth of the further row of saw teeth, are thus arranged on a straight line (as viewed from a side view toward the blade face). It could also be said that the saw-tooth tips of the further row of saw teeth span a plane or, in particular, are arranged on a saw-tooth tip plane. In principle, saw teeth of reciprocating saw blades may be profiled and/or offset, such that the tips can in part be arranged in a transversely offset manner in relation to the lateral faces of the reciprocating saw blade. The term straight line has therefore been chosen here for simplification. However, the further row of saw teeth, or saw-tooth tips, may also be arranged in a concave or convex row, such that they do not lie on a straight line, or the saw-tooth tips do not come to lie in a saw-tooth tip plane. Advantageously, production is simplified by the straight arrangement of the further row of saw teeth. The chip space can be enlarged in a constant manner. The quality of cut is improved; a reduced susceptibility to tearing is achieved.

It is additionally proposed that the first and the second row of saw teeth be each arranged on a straight line. Here, also, it is the case that the saw teeth, in particular the saw-tooth tips, of the saw teeth of the first and second row of saw teeth each come to lie on a straight line (as viewed from a side view toward the blade face), or each come to lie on a plane formed by the saw-tooth tips of the first, or second, row of saw teeth; in particular, on a respectively associated saw-tooth tip plane. However, the first and second row of saw teeth, or their saw-tooth tips, may also be arranged in a concave or convex row, or in another manner.

Advantageously, production is simplified by the straight arrangement. Constantly progressive (aggressive) or degressive sawing can be achieved, in particular, because of, respectively, the positive or negative broaching position. This results in a steadying of the cutting motion and the cut guidance, and thus also of the handling of the reciprocating saw blade. The sawing progress and the quality of cut are improved.

It is additionally proposed that the set-back, with respect to a so-called pitch of at least first and/or second and/or further saw teeth, of the corresponding rows of saw teeth, be between 10% and 35%, in particular between 15% and 30%, particularly preferably 25%. Relative to a width of the saw blade transversely in relation to the longitudinal axis and substantially parallel to the lateral face of the saw blade (not the thickness of the saw blade), the set-back may have a ratio of 1% to 20%, in particular 3% to 16.5%. Relative to a maximum width of the saw blade, the ratio is be preferably 3.4% to 6.8%, particularly preferably about 5.7%. Relative to a minimum width of the reciprocating saw blade, in particular in the region of the dividing plane of the reciprocating saw blade (for example, of a curved saw blade according toFIG. 5), the ratio is preferably 4.9% to 9.8%, in particular about 8.2%. The choice of set-back (see also above) can decisively affect the quality of cut in the region of the stroke reversal point, and thus decisively control, in particular improve, the quality of cut. Since the set-back region has saw teeth, this region also contributes to sawing, or removal of material. The aforementioned choice of size of the set-back achieves the result that the further row of saw teeth can contribute less, but still appreciably, to the progress of sawing. (A reference for no longer appreciable is a non-toothed saw blade portion). As a result, the quality of cut is improved perceptibly (by touch) and/or visibly (fewer tears) at the workpiece surfaces (upper side and underside) and, in particular, good sawing progress can nevertheless be achieved. An optimum can be achieved, in respect of a saw blade that is selected by way of example and described in greater detail in the description of the figures, with the particularly preferred values.

Furthermore, it is proposed that the first and/or second row of saw teeth have/has opposing directions of cutting. This means that the saw teeth, in particular the saw-tooth tips of the saw teeth of the first row of saw teeth, point in opposite directions to the second row of saw teeth, in particular in the opposite direction of cutting. In other words, the saw-tooth tips of the first row of saw teeth point toward the tip of the reciprocating saw blade, and/or the saw-tooth tips of the second row of saw teeth point toward the shank of the reciprocating saw blade. A relief angle typically comprises 30° to 45° in an opposite direction, in particular both relief angles are about 35°. Advantageously, workpiece tears at the respective workpiece surface (upper side and underside; or both potential visible surfaces) are reduced significantly as a result. The quality of cut is improved considerably. Upon the upward stroke toward the reciprocating saw, sawing is effected substantially by the second row of saw teeth, with respect to the parting plane of the saw blade; upon the downward stroke, sawing is effected substantially by the first row of saw teeth. (In particular, sawing, cutting, detaching and/or tearing is/are effected by the flanks of the saw teeth). The sawdust detaching motion is effected into the workpiece, and thus prevents workpiece parts from being torn out of the surface. The rounded (blunt), non-profiled backs of the respective saw teeth of the opposite row of saw teeth, in this example of the first row of saw teeth, which emerge from the workpiece upon the upward stroke, typically do not cause any surface tearing. Moreover, at most they contribute only to an insignificant degree to the progress of sawing; rather, they merely release previously sawn sawdust (chip ejection).

Furthermore, it is proposed that the further row of saw teeth have saw teeth of an opposing direction of cutting. These are advantageously arranged with mirror symmetry in relation to the dividing plane that runs in the longitudinal centre of, and normal to, the longitudinal axis, relative to the longitudinal extent of the further row of saw teeth. Or, in other words: the saw teeth are arranged with mirror symmetry in relation to a plane of symmetry that is normal to the longitudinal axis and that intersects the further row of saw teeth in its longitudinal centre. The aforementioned advantageous effects can thereby also be achieved in the set-back region. Owing to the fact that, however, the contribution of the further row of saw teeth is generally lessened (see above), at the same time the quality of cut can be improved at the reversal points (upper and lower dead points), or tearing can be avoided. In particular, tearing (with respect to the upward stroke (toward the reciprocating saw)) during sawing of thin workpieces, by the saw teeth of the further row of saw teeth (beyond the dividing plane, with respect to the reciprocating saw) that are adjacent to the second row of saw teeth, is thereby prevented. Insofar as these (critical) saw teeth emerge from the upper side of the workpiece during the upward stroke, their negative effect is lessened by the set-back (see above), but nevertheless the further region contributes to the progress of sawing, and allows gentle broaching of the workpiece (likewise positive for avoidance of tearing) at the turn points, or dead points or stroke reversal points.

Further, it is proposed that the saw teeth of the first and second row of saw teeth, in particular also the saw teeth of the further row of saw teeth, be arranged at least substantially with mirror symmetry in relation to the dividing plane, or plane of symmetry. The dividing plane, or plane of symmetry, is normal to the longitudinal axis of the reciprocating saw blade and intersects the further row of saw teeth in its longitudinal centre. “Substantially” means here, insofar as the longitudinal extent of the first and second row of saw teeth is identical. If, however, the longitudinal extent of the first and second row of saw teeth differs, the symmetry applies at least to identical distances with respect to the dividing plane. This allows simple production, for example as a result of only a single, simple resetting on the production machines.

It is proposed that the longitudinal extent of the second row of saw teeth be greater than or equal to the longitudinal extent of the first row of saw teeth, in particular greater by up to 50%, preferably greater by 15% to 35%. The longitudinal extent of the second row of saw teeth is, for example, 30 to 45 mm, in particular 41 mm, that of the first row of saw teeth, for example, 25 mm to 35 mm, in particular 30 mm. Typical workpiece thickness of up to 40 mm, or at least up to 30 mm, can thus be worked in an optimal manner, i.e. with little tearing.

It is additionally proposed that the longitudinal extent of the first or second row of saw teeth be 15% to 450% greater, in particular 30% to 85% greater, than the longitudinal extent of the further row of saw teeth. For example, the longitudinal extent of the first or second row of saw teeth is 10 mm to 26 mm, in particular 22.5 mm. This makes it possible, in the case of a stroke of a reciprocating saw of, for example, 26 mm and typical workpiece thicknesses of greater than a few millimetres, to ensure sufficient sawing progress and to prevent the first row of saw teeth, or saw teeth of the first row of saw teeth, from emerging from the lower workpiece surface (in the region of the lower dead point), and to prevent saw teeth of the second row of saw teeth from emerging from the upper workpiece surface (the workpiece surface facing toward the reciprocating saw; in the region of the upper dead point). The quality of cut is thereby improved.

The longitudinal extent of the further row of saw teeth is less than a stroke of a reciprocating saw intended for use of the reciprocating saw blade, in particular is 5% to 65% less, particularly preferably 10% to 15% less. As stated above, as a result the quality of cut is improved and tearing of workpieces, in particular from the upper and lower workpiece surface, is prevented.

It is additionally proposed that the saw teeth of the first and/or second and/or further row of saw teeth be profiled with a standard toothing or with a Japan toothing, in particular wherein they have no offset, or have an offset. This improves the sawing progress and/or the quality of cut.

Also claimed is a reciprocating saw having a reciprocating saw blade according to the disclosure.

