Abstract:
A hacksaw blade has a blade body that includes a cutting edge. One cutting-edge section is embodied in a concavely curved manner and at least one further cutting-edge section is embodied in a non-concave manner.

Description:
[0001]    This application claims priority under 35 U.S.C. §119 to patent application no. DE 10 2013 204 372.4, filed on Mar. 13, 2013 in Germany, the disclosure of which is incorporated herein by reference in its entirety. 
         [0002]    The disclosure relates to a hacksaw blade for a power tool, for example a jigsaw blade or reciprocating saw blade 
       BACKGROUND 
       [0003]    Hacksaw blades for portable power tools, which have a blade body which has a cutting edge having cutting teeth, and a fixing shank, via which the saw blade is fixable to the power tool, are known. Along its length, the cutting edge can have a concavely curved profile, as is described for example in JP 1999-373399, in DE 37 06 429 A1 or in JP 2004/119829. As a result of the concave shape, an improved sawing rate is intended to be achieved with low expenditure of force. 
       SUMMARY 
       [0004]    The disclosure is based on the object of using simple structural measures to configure a hacksaw blade, which executes an oscillating reciprocating movement during operation, such that precise workpiece machining is possible with a high cutting capacity over a long operating period. The disclosure relates to a hacksaw blade, for example a jigsaw blade or reciprocating saw blade, which executes an oscillating, reciprocating translatory working movement during operation. The hacksaw blade has a blade body having a cutting edge on which cutting teeth are arranged. A fixing shank, via which the saw blade can be fixed in a receiving device of the power tool, is connected to the blade body. The fixing shank is preferably formed in one piece with the blade body, with a multi-part embodiment also optionally coming into consideration. 
         [0005]    The cutting edge on the blade body has at least two differently shaped cutting-edge sections, of which one section is concavely curved, such that the cutting edge of the concave section is set back upwardly, and a further section, which immediately adjoins the concave section, is embodied in a non-concave manner. As a result, improved adaptation to particular workpiece geometries is possible, and so the latter can be machined with greater precision over an extended lifetime and with a greater cutting capacity. For example, tubular cross sections can be severed better with a saw blade which has concave and non-concave sections. 
         [0006]    The non-concave cutting-edge section is advantageously configured in a rectilinear manner and is located, according to a further expedient embodiment, adjacent to the saw blade tip. Thus, the concave cutting-edge section is located at a distance from the saw blade tip, and the section between the saw blade tip and the concave section is configured in a rectilinear manner. As a result, in particular sawing in the region adjacent to the saw blade tip is improved. 
         [0007]    It may furthermore be expedient for the concave cutting-edge section to be at a distance from the rear end, facing the fixing shank, of the cutting edge. In conjunction with the distance from the saw blade tip, the concave cutting-edge section is thus located at a distance both from the front and from the rear end of the cutting edge. A non-concave section, which is advantageously rectilinear and in particular in alignment with the front, rectilinear section adjacent to the cutting-edge tip, is also located, in this embodiment, between the concave cutting-edge section and the rear end of the cutting edge. 
         [0008]    It may be expedient to arrange the concave cutting-edge section eccentrically on the cutting edge, in particular such that the distance from the front end of the cutting edge is greater than the distance from the rear end of the cutting edge. The distance from the front end of the cutting edge is for example at least twice as large as the distance from the rear end of the cutting edge. Thus, a comparatively long, non-concave cutting-edge section, which is preferably configured in a rectilinear manner and in particular improves and makes easier the separating behavior during the machining of tubular workpieces, arises in the front part. 
         [0009]    According to a further expedient embodiment, the concave cutting-edge section is at least as long as the entire non-concave cutting-edge sections taken together. In this way, a sufficiently long concave section is ensured, which allows efficient machining in particular of curved workpieces while having an improved cutting-in behavior. 
         [0010]    The height of the concave cutting-edge section—as seen orthogonally to the cutting edge—is advantageously dimensioned such that an angle of taper is at most 3°, in particular at least approximately 1°, wherein the angle of taper designates the angle between the connecting line between the end points of the concave cutting-edge section and the connecting line between one of the end points and the maximum height of the concave cutting-edge section. 
         [0011]    According to a further expedient embodiment, the blade body can consist of a bimetal combination. The concave cutting-edge section can be restricted to a relatively hard HSS strip for the row of teeth, without extending into the carrier made of softer material. 
         [0012]    According to a further expedient embodiment, the back, located opposite the cutting edge, of the blade body is configured in a rectilinear manner. To the extent that the cutting edge has rectilinear sections, these extend parallel to the rectilinear back of the blade body. 
         [0013]    The curvature of the concave cutting-edge section can, according to an advantageous embodiment, be produced simultaneously with the introduction of the toothing during the production of the saw blade and thus takes place over the cutting-edge side. By contrast, the back of the saw blade, given a rectilinear embodiment of the back, remains unaffected. 
         [0014]    The toothing geometry can have constant or non-constant values with regard to pitch, height and angle. 
         [0015]    The length of the concave cutting-edge section can also be determined by parameters of the power tool in which the saw blade is inserted. Thus, it is for example expedient for the length of the concave cutting-edge section to correspond at least to a single stroke, preferably to a multiple of the stroke, for example to twice the stroke, which the saw blade executes during sawing operation. 
         [0016]    Optionally, further dependences of the geometric parameters of the concave cutting-edge section also come into consideration. Thus, it is for example possible also to set the length of the concave cutting-edge section in dependence on the diameter or the curvature of the workpiece to be machined. For example, the length of the concave cutting-edge section is at least as large as the diameter, preferably a multiple of the diameter, for example twice as large as the diameter of the pipes to be machined. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Further advantages and expedient embodiments can be gathered from the claims, the description of the figures and the drawings, in which: 
           [0018]      FIG. 1  shows a side view of a saw blade for a jigsaw or reciprocating saw, having a blade body with a cutting edge on which cutting teeth are formed, and having an integrally configured fixing shank for clamping into the power tool, wherein a section of the cutting edge is configured in a concave manner, 
           [0019]      FIG. 2  shows a saw blade corresponding to  FIG. 1 , having additional ratio details relating to the length of the concave cutting-edge section, 
           [0020]      FIG. 3  shows the concave cutting-edge section in an illustration with exaggeration of the concave elevation. 
       
    
    
       [0021]    In the figures, identical components are provided with identical reference signs. 
       DETAILED DESCRIPTION 
       [0022]    The saw blade illustrated in the figures is in the form of a hacksaw blade for a reciprocating saw or jigsaw and, during operation of the power tool, executes a translatory, oscillating, reciprocating working movement. The power tool is preferably a handheld power tool. 
         [0023]    The saw blade  1  illustrated in  FIGS. 1 and 2  has a blade body  2  and a fixing shank  3 , via which the saw blade  1  is connected to a receiving device of the power tool. The blade body  2  and the fixing shank  3  are formed in one piece. 
         [0024]    The blade body  2  has a cutting edge  4  having cutting teeth, which extends between a rear end, which faces the fixing shank  3 , and a front end, which is located adjacent to the saw blade tip  5 . The back  6 , opposite the cutting edge  4 , on the blade body  2  is embodied in a rectilinear manner. The cutting edge  4  extends at least sectionally parallel to the back  6 . 
         [0025]    The cutting edge  4  is subdivided into a total of three sections  4   a ,  4   b  and  4   c  that adjoin one another. The first section  4   a , which immediately adjoins the fixing shank  3 , is configured in a rectilinear manner, as is the front section  4   c  facing the saw blade tip  5 . These two rectilinear sections  4   a ,  4   c  are aligned and extend parallel to the back  6 . 
         [0026]    The intermediate section  4   b , arranged between the two rectilinear sections  4   a  and  4   c , of the cutting edge is formed in a concave manner and has an indentation facing the back  6 , as can be seen by way of the connecting line  7  which connects the two rectilinear cutting-edge sections  4   a  and  4   c . The tooth tips of the cutting teeth or saw teeth are at a distance from the connecting line  7  in the region of the concave cutting-edge section  4   b.    
         [0027]    The length of each section  4   a ,  4   b ,  4   c  is configured to be different. The central cutting-edge section  4   b , embodied in a concave manner, is placed eccentrically with respect to the longitudinal axis and is at a greater distance from the saw blade tip  5  than from the rear fixing shank  3 . Accordingly, the front, rectilinear cutting-edge section  4   c  is embodied in a longer manner than the rear, likewise rectilinear cutting-edge section  4   a . In the exemplary embodiment, the front, rectilinear cutting-edge section  4   c  is more than twice as long as the rear, rectilinear cutting-edge section  4   a . In the case of a blade length other than that illustrated, for example the section  4   c  adjacent to the saw blade tip  5  can be modified or the length of the concave section  4   b  can be changed. 
         [0028]    In the depicted example, the central, concave cutting-edge section  4   b  has a length which corresponds at least to the sum of the other cutting-edge sections  4   a ,  4   c . Depending on the blade length, however, the section  4   c  can be disproportionately larger and thus reduce the ratio. 
         [0029]    The concave cutting-edge section  4   b  can optionally be embodied in a part-circular manner. 
         [0030]    In  FIG. 2 , the hacksaw blade  1  is illustrated with the length of the concave cutting-edge section  4   b  in relation to two typical tubular workpieces  8  having a diameter d. The length of the concave cutting-edge section  4   b  is in this case at least twice as large as the diameter d of the pipes  8  to be machined. Ideally, the starting point or shank of the concave cutting-edge section  4   b  is located in front of the bearing point of the workpiece. 
         [0031]    Also indicated in  FIG. 2  is the stroke b which the saw blade  1  executes during the machining of a workpiece. The length of the concave cutting-edge section  4   b  is likewise at least twice as large as the stroke b. 
         [0032]    The length of the front, rectilinear cutting-edge section  4   c  is additionally at least twice as large as the length of the rear, rectilinear cutting-edge section  4   a.    
         [0033]    In  FIG. 3 , the cutting edge having the sections  4   a ,  4   b  and  4   c  is illustrated with an exaggerated central, concave section  4   b . The concave cutting-edge section  4   b  has an angle of taper a, which designates the angle between the connecting line  7 , which extends at the height of the tooth tips of the rectilinear cutting-edge sections  4   a ,  4   c , and a connecting line a which is located between one of the end points, for example the front end point of the concave cutting-edge section  4   b , and the maximum height h of this cutting-edge section  4   b . The angle α can also be determined from the tangent of the ratio of the height h to half the chord s/ 2  of the concave section  4   b . This angle of taper a is preferably at most 3°, in particular at least approximately 1°.