Abstract:
A saw blade with teeth has a tooth point with a tooth edge (E 1,  E 2 ). A tooth face is on the front side of the tooth and a tooth back is behind the tooth edge. A tooth gullet (G 1,  G 2 ) is defined as the space between the tooth edges of two adjacent teeth. The tooth edge (E 1,  E 2 ) extends between a right hand tooth corner (A 1,  A 2 ) and a left-hand tooth corner (B 1,  B 2 ). A first tooth gullet, disposed between the tooth edge (E 1 ) of a first tooth (T 1 ) and the tooth edge (E 2 ) of the next tooth (T 2 ) is beveled. A sloping surface (S 1 ) extends from the first tooth edge (E 1 ) in the rear end of the first tooth gullet downwardly along the tooth face and to at least the tooth bottom.

Description:
This application claims benefit of Provisional application No. 60/270,812 filed Feb. 23, 2001. 
    
    
     TECHNICAL FIELD 
     The invention concerns a band saw blade with teeth having a tooth point with a tooth edge, a tooth face on the front side of the tooth as viewed in the direction of sawing, a tooth back behind the tooth edge, and a tooth bottom between the tooth face on each tooth and the tooth back on the next tooth in front of said each tooth, and tooth gullets, wherein a tooth gullet is defined as the space between the tooth edges of two adjacent teeth, said saw blade having two planar sides; a right hand side and a left hand side when the saw blade is viewed obliquely from above in the direction of sawing, wherein said tooth edge extends between a right hand tooth corner and a left hand tooth corner with reference to said viewing direction. 
     BACKGROUND OF THE INVENTION 
     Saw teeth of band saw blade work as tiny planing tools generating chips at high speed by planing and/or tearing, the chips being collected and removed in the tooth gullets. The development of increasingly efficient band saws has aimed at further developing this planing and/or tearing function of band saw blades. It is a typical feature of band saw blades that the teeth are set or swaged, so that the kerf will be somewhat wider than the blade is thick. The kerf is formed due to their milling away material. 
     It is also typical for band saw blades that they vibrate and give rise to noise at a volume which in many cases can be uncomfortably high. Further, the surfaces of the kerfs will be grooved or otherwise uneven, which requires considerable finishing in those cases when smooth surfaces are desired. Among other drawbacks can be mentioned that setting and swaging cause wide kerfs and hence substantial losses of material. 
     BRIEF DISCLOSURE OF THE INVENTION 
     It is the purpose of the invention to provide a band saw blade which saws very silently, which does not give rise to inconvenient vibrations, which gives surfaces having a good smoothness and thin, material-saving kerfs when sawing in e.g. wood, plastic, meat and metal. 
     Surprisingly, these effects can be achieved with a saw blade according to the invention. A band saw blade designed in this way, wherein the saw blade in the region of the tooth gullets following directly upon one another are bevelled alternatingly to the left and to the right, has surprisingly turned out not to require any setting or swaging of the teeth in order to run freely in the kerf that is being established. The sawing is extremely easy to perform, without noticeable vibration, and very silent and gives cuts with good surface smoothness when sawing in for example wood, plastics, and metal. Without binding the invention to any specific theory, it can be assumed that the saw blade combines the planing operation of the teeth with the operation of tools which cut like knives. 
     Especially favourable results have been achieved when forming each tooth face F 1 , F 2  slightly concave. The hook angle a should preferably not exceed 15°, such that the strength of the teeth of the band saw blade is kept within acceptable limits. On the other hand the hook angle a should not be less than 1° in order to provide for a desired milling action. Preferably the hook angle is between 2-10°, more preferred about 3-8°. Moreover the tooth face F 1 , F 2  should be angled in relation to the extension of the band saw blade to form an angle f 1  which also is less than 15° but at least 1°, preferably 2-10°, more preferred about 3-8°. Also the bevelled surface S 1  may be angled at about the same amount, i.e. β is less than 15°, but more than 1°, preferably 2-10° and more preferred about 3-8°. Finally the same relation may be desirable in relation to the extension of the tooth edges E 1 , E 2  being alternately angled in relation to the horisontal plane along the band saw blade, i.e. forming an angle γ which is less than 15° but more than 1°, preferably 2-10°, more preferred about 3-8°. Finally it has been noted that the structural strength of the band saw blade according to the invention may be further improved if the tooth back H 1 , H 2  is formed slightly convex. 
     Successful experiments have been performed with saw blades designed in the above described manner, through sawing in fresh victuals, such as meat and fish etc, and in plastic, wood and comparatively soft metals, such as brass, wherein the saw blade consisted of a conventional, hardened carbon steel. It can be assumed that the same good results can be achieved also when sawing in harder materials, such as steel and other hard metals, if at least the saw teeth, or those parts thereof which are subjected to wear, consist of more qualified materials than hardened carbon steel, such as high speed steel, Stellite or cemented carbide. 
     In view of the successful experiments that have been performed with a saw blade designed in the above described way, one can also conceive that substantial improvements in comparison with prior art saw blades can be achieved also when the bevelled region has a smaller extension than what has been described above. It is, however, the opinion of the inventors that the bevelled region shall extend from the tooth edge of the first tooth point in the rear end of the first tooth gullet, down the tooth face and to at least the tooth bottom. Generally speaking, it can therefore be stated that the said region shall be bordered to the right by a first line which extends from a rear foot point defined by the right hand tooth corner of the first tooth edge or by a point on the first tooth edge, which point is nearer the right hand tooth corner than the left one, to a front foot point which borders on the left hand side of the saw blade in the region of the first tooth gullet or is a point on the tooth edge on the next tooth in front of said first tooth, to the left by the border line against the left planar side of the saw blade, and forwards by said first line and/or by the tooth edge of said next tooth when the front foot point of said first line lies on said next tooth edge; that the saw blade, within a region of a second tooth gullet between a second tooth and a next tooth in front of said second tooth is bevelled in the same way as in the first tooth gullet but instead to the right, and that the saw blade within the region of first and second tooth gullets between first or second teeth, on one hand, and teeth in front thereof, on the other hand, along the length of the saw blade, are bevelled in the said way alternatingly to the left and to the right in said first and second tooth gullets. 
     Probably, best results are achieved if all teeth and tooth gullets are designed according to the invention, wherein the material in the region of tooth gullets following consecutively directly after one another are bevelled alternatingly to the left and to the right. The invention, however, also can conceive that the saw blade within two or more tooth gullets following subsequently after each other is bevelled to the left, followed by a number of tooth gullets in which the saw blade is bevelled to the right and so on, repeatedly, although the inventors do not consider that that gives any significantly favourable effect. 
     The successful experiments with saw blades according to the invention have been performed with band saw blades. 
     Further characteristic features and aspects of the invention will be apparent from the appending claims and from the following description of the successfully tested embodiment and some other, conceivable embodiments. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     In the following description, reference will be made to the accompanying drawings, in which: 
     FIGS. 1A,  1 B, show a section of a band saw blade according to the first preferred, and 
     FIGS. 1C and 1D tested embodiment in a perspective view, from the side, in a vertical cross-section view and in a horisontal cross-section view, respectively, 
     FIGS. 2A,  2 B, illustrate a second, conceivable embodiment in a perspective view, 
     FIG. 2C is from the side, and from above, respectively; and 
     FIGS. 3A and 3B show a third, conceivable embodiment in a perspective view and from the side. 
    
    
     In the drawings, the saw blade has been shown with strongly exaggerated thickness. 
     DESCRIPTION OF EMBODIMENTS 
     With reference first to FIGS. 1A and 1B, there is shown a section of a band saw blade  1  according to an embodiment which, when sawing in wood, plastics, fresh victuals and in comparatively soft metals, such as brass, has turned out to give very good results, as has been mentioned in the foregoing. The sawing direction is shown by an arrow  2 . The blade thickness (gauge) is strongly exaggerated. A first tooth is designated T 1  and second teeth on each side of the first tooth have been designated T 2 . The tooth edges at the tip of the tooth points of the teeth T 1  and T 2  have been designated E 1  and E 2 , respectively. The tooth edge E 1  on the first tooth T 1  extends over the saw blade  1  between a right hand tooth corner A 1  and a left hand tooth corner B 1 , while the tooth edges E 2  extend between a right hand tooth corner A 2  and a left hand tooth corner B 2 . The right planar side of the blade  1 , which is hidden in FIGS. 1A and 1B, is denoted R, while the opposite, left hand planar side, turned towards the viewer, is designated L. A first tooth gullet between the tooth edge A 1  and the tooth edge A 2  in front thereof has been designated G 1 , while the tooth gullets in front of and at the rear of said tooth gullet G 1  have been designated G 2 . A tooth face on the first tooth T 1  in the tooth gullet G 1  is designated F 1 . A tooth back on the tooth T 2  in front thereof in the tooth gullet G 1  is designated H 1 , while the tooth bottom in tooth gullet G 1  is designated J 1 . Corresponding details in the tooth gullets G 2  are designated F 2 , H 2 , and J 2 , respectively. The tooth face F 1  is concave and it first extends downwards-rearwards from the edge E 1 , forming a hook angle α of approximately 5° (see FIG. 1B) whereafter it turns forwards towards the tooth bottom J 1 . The tooth back H 1  extends convexly upwards from the tooth bottom J 1  towards the tooth edge E 2  on the tooth T 2  in front thereof. 
     According to the embodiment shown in FIGS. 1A-1D, the saw blade is bevelled in the region of the entire tooth gullet G 1  in such a mode that the bevelled saw blade surface S 1  will slope towards the left hand side L of the saw blade forming an angle β of about 5° (see FIG. 1C) with said left side, which means that the bevelled region with said sloping surface S 1  will extend from the first tooth edge E 1  in the rear end of the first tooth gullet G 1 , down the tooth face F 1  and up the tooth back H 1  all the way to the tooth edge E 2  on the next tooth T 2  in front of the first tooth. The bevelled region S 1  is bordered to the right by a first line K 1 , which extends from the right hand tooth corner A 1  of the tooth T 1  to the right hand tooth corner A 2  on the next tooth T 2  in front of the first tooth T 1 . The line K 1  coincides with the plane of the right hand planar side R of the blade and forms an edge line of a first longitudinal edge X 1 , the edge angle β (see FIG. 1C) of which according the embodiment is about 5°. The said first longitudinal edge X 1  thus has the shape of a longitudinal knife edge in the region of the entire tooth gullet G 1  with an edge line K 1 , which follows the profile of the tooth gullet. The bevelled first region S 1 , which forms one side of the knife edge X 1 , is bordered to the left by the border line against the left hand side L of the blade, while the second knife edge side coincides with the plane of the right hand side R of the saw bade. 
     The saw blade  1  is bevelled in the same mode in the second tooth gullets G 2 , i.e. in front of and at the rear of the tooth gullet G 1  but with the bevelled saw blade surfaces S 2  instead sloping with the same amount, i.e. about 5°, to the right. The longitudinal tooth edges in the region of said second tooth gullets G 2  are referred to as second tooth edges and have been denoted X 2 . 
     The blade  1 , along its entire length, is provided with first teeth T 1  alternating with second teeth T 2  in front of and at the rear of the first teeth T 1  and with said first bevelled surfaces S 1  sloping to the left and second bevelled surfaces S 2  sloping to the right, as has been shown and described with reference to the illustrated section. The blade  1  and the teeth T 1  and T 2  are unset and unswaged, which implies that the tooth corners A 1  and A 2  and the edge lines K 1  of the first longitudinal knife edges X 1  will coincide with the plane of the right hand side R of the saw blade  1 , and that the edge lines K 2  of said second, longitudinal knife edges with their edge lines K 1  will coincide with the plane of the left hand side L of the blade. 
     FIG. 1C is showing a cross-sectional vertical view along the imaginary line C—C. As can be seen in FIG. 1C the tooth edge E 2  will not be horizontal but sloping forming an angle γ which is about 5°. Accordingly the left hand tooth corner B 2  of the second tooth edge E 2  will be positioned at a higher level than the right hand tooth corner A 2 . However, the right hand tooth corner A 1  of the next tooth will be positioned at the same level as the left hand corner B 2  of the tooth in front of it. Hence there is formed a kind of V-shaped pattern when viewing in the direction of the saw blade of a vertical cross-sectional view. 
     In FIG. 1D, which is a cross-sectional view along the horizontal line D—D, it can bee seen that each horizontal line of the tooth face F 1  will form an angle f 1  in relation to a perpendicular line through the saw blade. In the same manner a horizontal line of the tooth back H 2  belonging to the same tooth T 1  will form an angle f 2  in relation to perpendicular plane through the saw blade, but in the opposite direction. Accordingly the form of the cross-section is frusta conical. The angles f 1  and f 2  are the same according to the preferred embodiment, i.e. about 5°. The tooth edge E 1  will accordingly have a rake angle which is the same as the angle f 1  of the tooth face F 1 . 
     In the embodiments according to FIGS. 2A-2C and according to FIGS. 3A-3B the tooth and tooth gullet profiles have the same general shape as in FIGS. 1A and 1B, but the bevelled saw blade surfaces S 1 , S 2  have a smaller extension than according to the embodiment that has been described with reference to FIGS. 1A and 1B. In FIGS. 2A-2C a bevelled saw blade surface in the first tooth gullet G 1  has been designated S 1  as above. This surface S 1  is bordered at the rear by the tooth edge E 1  of the first tooth T 1  and to the left by the left hand saw blade surface L. To the right and forwards it is bordered by the first line K 1 , which in this case extends from the right hand tooth corner A 1  on the tooth edge E 1  to a foot point C, which borders on the right hand side of the saw blade in the region of the first tooth gullet G 1  at a distance ahead of the tooth bottom J 1 , more particularly in the start region of the tooth back H 1  of the next tooth T 2  in front of the first tooth. The bevelled surface S 1  (which is shaded in FIG.  2 C), according to this embodiment, thus extends from the tooth edge E 1  beyond the tooth bottom J 1  and a distance up the tooth back H 1  (the non shaded surface in FIG. 2C of the tooth back is not bevelled). In the region of the second tooth gullets G 2 , the blade is bevelled in the corresponding mode but instead sloping to the right according to the same principle that has been described with reference to the preferred embodiment. 
     In the embodiment according to FIGS. 3A and 3B, the bevelled surfaces S 1  and S 2  have been given a still smaller extension, comprising only the tooth face F 1  and F 2 , respectively, wherein said first line K 1  extends from the right hand tooth corner A 1  to a foot point C′ in the tooth bottom J 1 . Also in this case, every second tooth gullet is designed with the bevelled surface S 1  sloping to the left and every second tooth gullet G 2  designed with the bevelled surface S 2  sloping to the right, i.e. mirror-invertedly with reference to the sloping bevelled surface S 1 , as is analogously shown in FIG. 2C for the second embodiment. 
     According to a preferred mode of production the gullets are first formed by means of punching. Preferably the punches are move along the angles that are desired in relation to the produced surfaces such that the desired angle of each surface (e.g. the tooth face, the tooth back) and edge (e.g. each tooth edge) is formed during punching.