A saw tooth, a saw blade comprising the saw tooth, and uses thereof

Abstract

A saw tooth (2a;2b;2c;2d;2e;2f;2g) and a saw blade (1a;1b;1c;1d;1e;1f;1g) comprising one or more of said saw teeth (2a;2b;2c;2d;2e;2f;2g), wherein said band saw teeth (2a;2b;2c;2d;2e;2f;2g) comprises a first tooth face part (9a;9b;9c;9d;9e;9f;9g) arranged at a first hook angle (β;β') and a second tooth face part (13a;13b;13c;13d;13e;13f;13g) arranged at a second hook angle. The first hook angle (β;β') is different from the second hook angle (γ;γ'). Preferably the fist hook angle (β;β') is higher than or equal to 36°.

Description

[0001] A saw tooth, a saw blade comprising the saw tooth, and uses thereof.

[0002] The present invention is directed to novel geometries and designs of teeth of saw blades of wood saws, where the saw blade is of the kind that undertakes a linear movement through the workpiece. Such wood saws may in particular, but not exclusively, be band saws and frame saws.

[0003] In particular the present invention is directed to novel geometries and designs of teeth of saw blades for large band saws for high efficient sawing and cutting different materials including wood, such as cutting timber, logs and trunks at timber mills. Such large band saws are e. g. described in the applicant's International patent application no. W02018 / 011120.

[0004] Circular saw blades that rotate about an axis during cutting are not part of the present invention.

[0005] Prior art band saw blade geometries and functions are described in details in the following literature: " The Handbook for successful sawing, by Sandvik, S-336-ENG. 4.2007", " Wood Bandsaw blade manual, by Uddeholm strip steel AB, 2001", " Handbok for trabandsagblad, by Uddeholm strip steel AB 4.2003", " How to increase profit in bandsawing, By Uddeholm AB, USAB 85.03.01. 3000 Nermans 5020069", " Traband sagblad tilvirkning och underhall, by Uddeholm Strip, 1994", and " The cutting behavior of band saws, by Bruce Lehmann, UBC 1993".

[0006] The hook angle is defined as the angle between a tooth face and a line perpendicular to a baseline of the saw blade. The hook angle is thus the amount of forward or backward lean of a tooth.

[0007] Within the patent literature European Patent no. EP 2 322 305 Al discloses a known band saw blade for cutting metal, and wherein the band saw teeth have e. g. an upper hook angle of25°, a lower hook angle of 0°, and a back angle of 25°. US patent no. 6,598,509 discloses similar band saw teeth with an even smaller upper hook angle, and a high back angle of about 30°.

[0008] German patent no. DE 173955 discloses another known tooth for a band saw blade. Said band saw tooth have parallel upper and lower tooth face parts offset each other by intermediate tooth steps. As the upper and lower tooth face parts are parallel their respective hook angles are identical.

[0009] The structure of different trees is never the same. So the structure of logs varies from start to finish of a log, and from side to side of a log. Therefore known band sawing technology is, due to the nature of the wood, the speed of the band saw blade, and thus of the tooth, and of the saw chip (s) per tooth challenged regarding controlling the saw chip when it leaves the upper tooth part of the band saw tooth, The cutting force compresses and crushes the saw chip against the intermediate step of a stepped band saw tooth, thereby packing the crushed saw chip towards the intermediate tooth step. The crushed saw chip creates a rounding of the intermediate tooth step, whereby shooting of the crushed saw chip off the band saw tooth becomes difficult and uncontrolled.

[0010] Further problems with the geometry of known band saw tooth profiles are that their hook angle (s) is / are rather low. So instead of cutting the wood fibers the tooth face (s) torns, crushes, rips up and / or breaks the wood fibers, thereby causing resistance for moving the saw blade to make the kerf, rough surfaces, and they require a lot of energy. Further the crushed and broken wood need to be scraped out by the same or subsequent band saw tooth, and saw chip and sawdust tend to at least temporarily pile up and pack in the gullet and around the tooth tip.Further problems is that conventional profile grinding machines cannot grind teeth having unparallel hook angles of first tooth part and second tooth face part, respectively e. g. upper and lower tooth parts.

[0011] Importantly, hook angles have large effects on cutting resistance, chip disposal, cutting temperature and saw blade life. Increasing the hook angle in the positive direction improves sharpness, but at the costs of decreased lifetime of sharpness. The lower the hook angle becomes, thus the more vertical the tooth face becomes, the more force and power is required to drive the band saw tooth through the workpiece, and the wood fibers tend to be torn or broken rather than cut and leaves a frayed cut. On the other hand the higher the first hook angle becomes the sharper an upper first tooth face is, which makes it easier to drive the band saw tooth / band saw teeth or tooth / teeth of a frame saw through the workpiece, but at the costs of a fragile and less durable tooth.

[0012] In the following the terms "band saw" is used for all kinds of wood saws that perform a linear movement through the wood during cutting. The term "band saw blade" refers to the orbiting blade on such band saws. Within the scope of the present invention the term "band saw blade" includes the blank, any intermediate products that eventually results in the final operative band saw blade ready to be placed in operative condition on a band saw, as well as strip steel, and new and used band saw blades, in particular band saw blades intended for being used on a large band saw for processing of logs and timber blocks.

[0013] The term "frame saw" is to be understood in its conventional meaning. The frame saw also make a linear movement through the wood during cutting.The band saw blade has "band saw teeth" and the frame saw has "teeth of a frame saw" for cutting through the wood in the linear movement. The teeth may be set or not set, have any tooth pitch, and be selected in accordance with the kind of wood to be cut.

[0014] It is main aspect of the present invention to provide alternative designs and geometries of teeth of band saw blades and of blades of frame saws.

[0015] It is a further aspect of the present invention to provide a band saw blade or a blade of frame saw with a tooth having the advantages of both high and low hook angles.

[0016] It is a further aspect of the present invention to provide a band saw blade with band saw teeth or providing a blade of a frame saw with saw teeth, which teeth having an improved ability to remove saw chips and saw dust.

[0017] It is a further aspect of the present invention to provide a band saw blade with band saw teeth or providing a blade of a frame saw with saw teeth, which teeth make a smooth and neat cut.

[0018] It is a further aspect of the present invention to provide a band saw blade or providing a blade of a frame saw that in use requires less power and energy for cutting wood than hitherto known.

[0019] It is a further aspect of the present invention to provide a band saw blade with band saw teeth or providing a blade of a frame saw with saw teeth, where cut off wood material does not build up between adjacent band saw teeth, clog the gullet or stick to the band saw teeth or the teeth of a blade of a frame saw.It is a further aspect of the present invention to provide a band saw blade with band saw teeth or providing a blade of a frame saw with saw teeth, which teeth preserve sharpness and which teeth are less fragile than hitherto known despite novel geometries.

[0020] The novel and unique features whereby these and other aspects are achieved according to the present invention consists in a band saw tooth or a saw tooth of a blade of a frame saw, which saw tooth comprises at least a first tooth face part arranged at a first hook angle and a second tooth face part arranged at a second hook angle, wherein the first hook angle is different from the second hook angle whereby the first tooth face part and the second tooth face part becomes non-parallel.

[0021] The first tooth face part may be an upper first tooth face part arranged at a first hook angle, which is an upper hook angle. The second tooth face part may be a lower tooth face part arranged at a second hook angle, which is a lower hook angle. The second tooth face part may be the lowermost tooth face part before the tooth profile extends into the gullet, or another tooth face part below the first tooth face part, which may be the uppermost free tooth face part of the tip of the saw tooth. Emphasize is made that further tooth face parts at same or other hook angles can be interposed between said first tooth face part and said second tooth face part.

[0022] Within the scope of the present invention the term "first tooth face part" thus means the upmost part or section of the tip of the tooth that makes the actually cutting through the workpiece. The free tip edge of the "first tooth face part" is the part of the tooth that hits the workpiece first and is responsible for starting breaking and / or cutting the wood fibers.Within the scope of the present invention the term "second tooth face part" thus means the section of the tooth tip arranged closer to the gullet than the "first tooth face part". The "second tooth face part" contributes a. o. in the progress of the saw blade through the workpiece.

[0023] Due to the tooth design of the present invention with different hook angles of the first tooth face part and of the second tooth face part the strength of such a tooth, and the durability of its sharpness, are increased compared to known band saw blade teeth.

[0024] Preferably the first hook angle is higher than or equal to 36 °.

[0025] The following technical terms and definitions in the below Table will be used when discussing the saw teeth of the present invention:

[0026] Hook angle The hook angle is defined as the angle between a tooth (β;γ) face and a line perpendicular to a longitudinal axis of the saw blade. The hook angle is thus the amount of forward or backward lean of a band saw tooth or a tooth of a frame saw. The hook angle is also known as the rake angle. As described in the cited literature hook angles are conventionally below 30°. At higher hook angles there is a significantly increased risk that a band saw blade runs off the pulley wheel (s ) of the band saw, and that the saw blade self-pulls through the workpiece, so there is a prejudice within the art to use high hook angles of more than 30°.

[0027] Back angle The term back angle refers to the angle between the (<p) tooth back surface at the tooth tip and a longitudinal axis of the saw blade. The prior art advises against back angles of less than 10°. The back angle prevents the tooth back from rubbing against the wooden workpiece. The back angle is also known as the flank

[0028]

[0029] angle or back clearance angle or just clearance angle, and is discussed in details in the above reference literature.

[0030] Tooth angle The angle between the hook angle and the back angle. (CO) The tooth angle is conventionally above 50°, to thereby traditionally maintain a strong saw tooth. The tooth angle is also called the sharpness angle. For a standard saw blade, the hook angle, the back angle, and the tooth angle all add up to 90 °.

[0031] Tooth back The angled back surface of the saw tooth opposite the tooth face.

[0032] Blade back The body of the saw blade not including the tooth / teeth.

[0033] Gullet As the saw tooth scrapes away the wood, the wood chip curls into the area and volume, the gullet, between the adjacent tooth tips, which area may be more or less curved or flat, or combinations thereof.

[0034] Gullet The distance from the tooth tip to the bottom of the depth gullet.

[0035] Tooth tip The part of the saw tooth that hits the workpiece first and is responsible for breaking and cutting the wood fibers. The tooth tip constitutes the majority of the cutting zone.

[0036] Tooth face The surface of the saw tooth on which the wood chip is formed. The upper tooth face part and the lower tooth face part are parts of a stepped tooth tip. The lowermost tooth face part extends into the gullet.

[0037] Tip edge The uppermost and front-most part of the tooth tip that hits the workpiece first.

[0038] Tooth set The misalignment of the saw teeth to the side, thus the bending of the saw teeth right or left beyond the body of the saw blade, thus beyond the blade back. The tooth set affects cutting efficiency and wood chipcarrying ability.

[0039] Cutting The cutting zone is the area that breaks / cut the wood zone fibers. The cutting zone of a tooth of e. g. a band saw blade for a large band saw is typically delimited by a sector of a circle having a radius between 5 - 10 mm, where the center of the sector of the circle is at the

[0040]

[0041] tip of the tooth tip.

[0042] Side The lateral distance e. g. a band saw tooth projects clearance beyond the blade back. The side clearance creates a (a) kerf in the workpiece that is slightly wider than the blade back. This extra space prevents the sides of the saw blade from rubbing against the wood being cut, which reduces friction and heat buildup. The side clearance angle is typically at least 2° radially and at least 2° axially of the band saw blade, where radially means perpendicular to the back of the band saw blade.

[0043] Chamfer A chamfer or chamfering of e. g. a band saw tooth refers to a small, angled bevel on a band saw tooth edge.

[0044] Gauge The thickness of the band saw blade or of the blade of a frame saw. The thickness gives the saw band more stability and influences the torsion resistance. The thicker, the stiffer, and the straighter the cut.

[0045]

[0046] The features listed above refer to features of the geometry of a tooth of a band saw blade or a tooth of a blade of a frame saw, and are generally known to the persons skilled in the art of such saw blades. The Greek symbols for respective angles will be adhered to in the detailed description of the invention.

[0047] Within the traditional art of wood cutting band saw blades and frame saw blades have positive hook angles of around 10-30° when cutting soft woods, and positive hook angles of around 0-25° when cutting hard woods. A positive hook angle pulls the saw blade into the wood for fast cutting and efficient chip removal, while smaller hook angles are less aggressive and provide more control of the movement of the saw blade as it counteracts the saw blades tendency of self-feeding or selfpulling into the wooden workpiece.Despite the prejudices within band saw blade manufacturers, the band saw teeth and / or frame saw teeth according to the present invention can be made with first hook angles higher than or equal to 36°, as the second hook angle is kept different from the first hook angle, and not the same as in the prior art stepped band saw teeth. Within the scope of the present invention saw teeth can be designed accordingly with a specific geometry to optimize cutting efficiency and provide very clean smooth cuts and kerfs with improved duration of the saw blade.

[0048] By dividing the profile of the tooth face into at least two tooth face parts where at least the first tooth face part acts as the cutting tooth part and the rest of the geometry and profile of the band saw tooth serves for chip and saw dust transport and removal, a more efficient and stable saw tooth can be obtained, even for a hook angle of an uppermost first tooth face part as high as 36° or above.

[0049] Due to the saw tooth design of the present invention with nonparallel different hook angles of the tooth face parts, the first hook angle can be made higher than for conventional band saw teeth, without the strength of such a saw tooth, its durability and its sharpness is compromised. Said features may even be improved compared to known band saw teeth or know frame saw teeth having parallel tooth face parts at same hook angles.

[0050] To provide a strong, durable and stable band saw blade, which is fast-feeding without being excessive weak, the first tooth face part may in a preferred embodiment have the positive first hook angle of at least 36°, and the second tooth face part may have a positive second hook angle, wherein the positive first hook angle can be higher than the positive second hook angle.

[0051] The higher the first hook angle becomes the more capable the band saw tooth is in attacking and cutting through the woodenworkpiece, e. g. through timber, and doing so with minimum power consumption.

[0052] Furthermore, said first tooth face part with a positive first hook angle that is higher than the positive second hook angle of the second tooth face below the first tooth face part contributes to performing the cut without the saw blade looses its stability during cutting. Yet an advantage is that with a tooth face that includes tooth face parts with a positive first hook angle that is higher than the positive second hook angle, the combined cutting angle and / or cutting radius of the tooth face can be increased in the cutting zone of the saw tooth, without loosing the stability of the saw blade, and without loosing the strength of the saw tooth.

[0053] The higher the first hook angle the more aggressive the saw tooth is. Within the scope of the present invention the first hook angle can be substantially any angle higher than 36°.

[0054] In preferred embodiments the first hook angle may be higher than or equal to 37°, or higher than or equal to 38°, higher than or equal to 39°, or higher than or equal to 40°, or higher than or equal to 41°, or higher than or equal to 42°, or higher than or equal to 43°, or higher than or equal to 43°, or higher than or equal to 44°, or higher than or equal to 45°, or higher than or equal to 46°, or higher than or equal to 47°, or higher than or equal to 48°, or higher than or equal to 49°, or higher than or equal to 50°. Any angle selected from the group of angles of 51°, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59° and 60 is however within the scope of the present invention. The choice depends primarily on the type of wood.

[0055] A first uppermost hook angle of 45° has been shown by the inventor of the present invention to be universal for manytypes of wood. At a first uppermost hook angle of 45° the vertical force component (y direction) and the horizontal force component (x direction of linear movement) of the force that the tooth tip attacks the wood with have equal size, whereby the forces applied during cutting can be distributed evenly to the wooden workpiece. The preferred first hook angle of 45° performs optimum cuts through the cell structure of a tree trunk and through knots that run across the cutting line, thus perpendicular to the tooth face that attack the wooden workpiece. A first hook angle of 45° moves the wood chip away from the tooth tip the fastest ever possible. If the wood, such as the tree trunk, has very few knots, very long fibers and soft structure, the first hook angle can even be increased further up to e. g. 80° to achieve a better cut of the wood fibers.

[0056] Preferably the first hook angle may be higher than the second hook angle. Optionally the second hook angle may be at least 12.1°.

[0057] The first tooth face part and the second tooth face part may have various geometrical features including one or more of that:

[0058] • the second tooth face part has a length that is equal to or longer than the length of the first tooth face part, and

[0059] • the length of the first tooth face part and / or the second tooth face part is minimum 1 mm, which tooth face part should not be construed as the intermediate tooth steps discussed below.

[0060] The second tooth face part and the first tooth face part can in preferred embodiments be offset each other by at least oneintermediate tooth step that can be curved or straight. The at least one intermediate tooth step can, but need not, take active part in the cutting process, whereby a long tooth face with tooth face parts with different geometry, properties and functions can be obtained. The combination of different properties and functions may be beneficial when passing e. g. a band saw tooth through the wooden workpiece.

[0061] The profile and geometry of the at least one intermediate step of the saw teeth according to the present inventions are designed to control the ejection angle of the saw chip so that the saw chip is pushed forward as far as possible towards the tooth back of the next saw tooth in an improved controlled manner wherein the shape of the saw chip maintains coarse and intact. The sharpness of the saw teeth according to the present inventions is utilized to keep the wood fibers of the saw chip more intact, united and structured than hitherto known, so that the free tip edge that cuts through the fibers of the wood ploughs the wood chip off the wooden workpiece in a manner whereby the saw chips are ejected as a jet of chips that changes direction due to the turning radius at the at least one intermediate tooth step, which turning radius forces the saw chips in the cutting direction and into the gullet. The at least one intermediate tooth step advantageously ejects the saw chip and saw dust away from the first tooth face part at the free tooth tip of the saw tooth better than hitherto known.

[0062] The overall tooth face of the tooth tip may in some embodiments comprise more than one intermediate tooth step in extended sequence in-between the first tooth face part and the second tooth face part. The number of intermediate tooth steps may be at least 1, 2, 3, 4, 5 or 6. All intermediate tooth steps may or may not have same angling and / or curvature. In case of more than one intermediate tooth step, the overall tooth face between the first tooth face part and the second tooth facepart has corresponding intermediate tooth face parts with the intermediate tooth steps in between.

[0063] As an example the at least one intermediate tooth step may extend into a third tooth face part in form of a third section, which third section preferably may have a positive third hook angle, and optionally extend directly or via a further intermediate step into the second tooth face part.

[0064] A free tip edge of the upper tooth face part of the band saw tooth may be arranged protruding beyond, or may be in, the plane of the second tooth face part seen in a cutting direction of a band saw blade.

[0065] Such at least one intermediate tooth step that e. g. can protrude from a second or third tooth face part above it, and e. g. extend from below the first tooth face part, may thereby offset the below subsequent tooth face part, e. g. offset the second tooth face part or an intermediate tooth face part, such as the third tooth face part, in a position e. g. retracted from the previous tooth face of the previous tooth face part opposite the tooth tip, to thereby arrange the first tooth face part and at least the second tooth face part angled in relation to each other, whereby the respective tooth face planes of the first tooth face part and at least the second tooth face part are not parallel. The at least one intermediate tooth step can be arranged at any convenient angle between adjacent tooth face parts, including acute, right or blunt angles.

[0066] The first tooth face part of the band saw tooth of the present invention cuts and pushes the wood fibers from the cut and kerf away from the free tip edge of the tooth tip.

[0067] As the first hook angle is higher than in e. g. the prior art band saw teeth the wooden fibers are actually cut more optimal. The wooden fibers are cut as a more coherent chip structure,and are less finely comminuted as it may happen with e. g. prior art band saw teeth. The fibers resulting from the cutting and the kerf will not to the same degree as for prior art band saw teeth clog and remain as a lump in the transport zone in front of the tooth face of the band saw tooth when the band saw tooth moves ahead and eventually leaves the workpiece being cut.

[0068] The at least one intermediate tooth step of a band saw tooth can expediently assist in guiding and expelling saw dust and chip structures from the cut towards a tooth back of the next saw tooth in front of said saw tooth and out of its gullet. The saw tooth of the present invention therefore leaves minimum cut off wood material, such as broken fibers, saw dust and saw chips, on the workpiece and on the saw teeth, compared to prior art saw teeth.

[0069] In an embodiment with a curved at least one intermediate tooth step, said curvature may improve and control the above-mentioned guiding and transport of saw dust and saw chip structures even further. The geometry of the at least one intermediate tooth step can thus be designed to direct cut off wood matter in a specific direction, which direction may depend on a. o. on the type of wood and its tendency of saw dust and wood chips thereof to stick, pack and pile up.

[0070] The appropriate geometry of the intermediate tooth step may thus be selected dependent on the type of wood to be cut. For example "soft wood", thus fast growing wood with relatively loose wood fibers, may be easier to cut than the fibers of "hard wood" with dense fibers. So for "soft wood" the radius of curvature of the intermediate tooth step may be higher than for "hard wood", where a small radius of curvature of the intermediate tooth step may be better to break up / rip up the fibers so that the chips do not become too coarse and too long.In alternative embodiments the first tooth face part can have a positive upper hook angle and the lower tooth face part, and optionally any intermediate tooth face parts, can have a zero or negative second hook angle, to thereby further inhibit the tendency of the band saw blade to "climb" the material being cut. In such an embodiment the second hook angle has backwards lean, thus leans forward from the intermediate tooth step, to counteract the positive first hook angle that has forward lean and overhangs the at least one intermediate tooth step to break the wood fibers. These designs and geometries of a saw tooth of the present invention have a highly improved capability to scrape the wood during cutting, whereby a clean finish can be obtained. Emphasize is made that within the scope of the present invention a positive first hook angle is also higher than a zero or negative second hook angle.

[0071] As mentioned above an edge of the free tip of the tooth tip may advantageously protrude beyond the plane of the second tooth face part, be in the plane of the second tooth face part, or the tip edge may be retracted from the plane of the second tooth face part.

[0072] For example, in some embodiments the first hook angle may be selected to arrange the free tip edge of the tip of the saw tooth to extend beyond a line that extends perpendicular to a longitudinal axis of the blade back of the band saw blade, and through a free end of the intermediate tooth step at the transition of the upper tooth part into the second tooth part, and wherein said free tip edge of the tooth tip does not intersect, or is in, a plane including the second tooth face part.

[0073] In some alternative embodiments the first hook angle can be selected to arrange the free tip edge of the tooth tip to protrude beyond a line that extends perpendicular to a line that extends perpendicular to a longitudinal axis of the bladeback and through a free end of the intermediate tooth step, and wherein a plane including the first tooth face part does intersect a plane including the second tooth face part to thereby increase the size of the combined hook angles more than for the embodiment of a saw tooth described just above this one.

[0074] According to the present invention the second tooth face part can in some alternative embodiments be retracted from the first tooth face part, whereby the tip edge of the free tip of the tooth tip protrudes beyond the second tooth face, and optionally also beyond the intermediate tooth face (s), and beyond further intermediate tooth face parts if such are part of the tooth. In case of further intermediate tooth steps and intermediate tooth face parts those may be similarly retracted.

[0075] For prior art band saw teeth for cutting wood the traditional back angle is at least 10°. Such a high back angle is aimed for to reduce resistance during cutting. In contrast to the prior art, and as prejudiced in the prior art, according to the present invention it may be preferred that the tooth back of the saw tooth of the present invention is inclined in relation to the blade back but to a lesser extent than for known saw teeth, in particular for known band saw teeth. Said tooth back of the present invention may be curved or straight. Preferably said tooth back has a back angle less than or equal to 10°, more preferably said back angle may be less than or equal to 8°, more preferred said back angle may be less than or equal to 5°, even more preferred said back angle may be less than or equal to 4°, even more preferred said back angle may be less than or equal to 3°, or less than or equal to 2°, or less than or equal to 1°. By selecting the appropriate back angle for a tooth of the present invention the back angle can either increase ability, thus be an accelerator, or decrease ability, thus be a decelerator, of the band saw teeth of the band sawblade self-feeding into the workpiece and thereby keep the band saw blade stable on the pulley wheels during cutting.

[0076] According to the present invention the degree of the back angle may be determined as low as possible for the space behind the tooth back to be sufficiently free to avoid friction between the wood and the tooth back. Therefore the degree of the back angle may be determined based on the relation between the intended thickness of a saw chip, thus the cut per tooth, and the distance between the free tip edges of two consecutive tooth tips. An intended thick cut per tooth may require a higher back angle than for a lower cut per tooth if the distance between the free tip edges of two consecutive tooth tips are the same.

[0077] The tooth back may have an upright protrusion or plateau spaced from the free tip edge of the tooth tip of the band saw tooth. Such upright protrusion or plateau may advantageously, optionally together with the back angle of the teeth of the present invention, counteract the band saw tooth's ability of self-pulling into the wooden workpiece, and thereby also keep the band saw blade stable on the pulley wheels during cutting.

[0078] The band saw tooth of the present invention may advantageously be provided with a hard material tipping as the strength of these hard materials makes the tooth tip more resistant to wear, thereby prolonging lifetime of said band saw tooth and prolonging the periods between grindings for sharpening the band saw teeth and maintenance of the band saw blade. Suitable hard tipping materials include, but are not limited to, carbide, ceramic, CBN and Stellite. " Stellite" is a registered trademark of Kennametal Inc. and is used in association with cobalt-chromium alloys.In preferred embodiments of a band saw tooth according to the present invention at least a length of the tooth back closest to the upper tooth face can have a chamfer to enforce the corners of the tooth tip along its length.

[0079] A chamfer reduces the uppermost width of a band saw tooth and chamfers parallel to the tooth back of known teeth having back angles much higher than 10° are known. However chamfers that follow the tooth ridge of the band saw tooth of the present invention having a back angle much closer to 0° are not known in the art of wood cutting and band saw blade manufacturing.

[0080] The slightest damage to an edge of the band saw tooth will inherently increase the cutting resistance inadequately at that location resulting in outwards deflection of the band saw tooth and / or that the entire saw blade is pushed in the opposite direction, and in uneven cuts and ripping of wood. Adding a chamfer or bevels to the tooth back of a band saw tooth of e. g. a band saw blade may positively affect the cutting performance of the saw blade. Accordingly, chamfering the band saw teeth offers several key advantages for cutting performance, durability, and safety. Advantages of chamfering the tooth back include but are not limited to extending saw blade life as the chamfers protect the brittle cutting edges from premature damage, and therefore significantly increases the lifetime of the band saw teeth. Yet an advantage of chamfering the tooth back of at least the tooth tip is that the angled cut of the chamfer, thus the bevelling, makes the band saw tooth less prone to chipping, cracking and breaking, especially when cutting dense and hard wood, whereby the durability of the band saw tooth is significantly improved.

[0081] The chamfers strengthen the saw tooth, making it more resistant to impacts and to the stress of cutting through wood materials, and makes very clean and smooth cuts.Preferably both sides of the saw tooth back can have chamfers, which help to keep the saw blades cutting line straight and the cut smooth. Preferably the chamfer along the tooth back may extend from the free tip edge at least a distance along the tooth back.

[0082] Such a chamfer, which may extend in the longitudinal direction of the saw blade, may be parallel to the blade back, or follow the curvature of more or less of the tooth back of a saw tooth, to thereby confer different properties to the saw tooth depending on the choice of the orientation of the chamfer (s).

[0083] The orientation of opposite chamfers may be the same or different, but preferably opposite chamfers are mirror-shaped.

[0084] A chamfer that follows the back angle or the curvature of the tooth back, at least at the tooth tip, will function similar as the tooth back, and act as an accelerator or decelerator. A chamfer parallel to the blade back or close to being parallel to the blade back induces cutting resistance and makes a sideways decelerator or brake or stopper against sideways selfpulling of the band saw tooth into the wood, resulting in a consistent, clean cut and prolonged operational time of the saw blade.

[0085] When cutting through the wood the chamfer is pressed into the wood that the tooth tip has not removed, thereby achieving the advantageous that the tooth back forces the band saw tooth to stay in the kerf that the tooth tip just has made.

[0086] The nature of the wood will determine where to place the chamfer, the size of the chamfer and the design of the chamfer. As mentioned above a chamfer can be a 45° corner, be on the sides of the tooth tip, be on top of the edge of the tooth tip, be rounded, e. g. concave or convex, or straight to control and stabilize the cutting action.The saw tooth of the present invention may have side clearance in relation to the blade back. The side clearance creates a kerf width that keeps most of the saw blade free of frictional contact with the cut wood surfaces. The side clearance may be provided on one side of the saw tooth or on both opposite sides of the tooth tip.

[0087] In accordance with the definition defined in the above Table, preferably the side clearance angle of the blade back of the saw tooth the prior art is recommended to be above 2° radially and 2° axially to create a free tooth tip.

[0088] In accordance with the present invention preferably the side clearance angle may be below 1.5° radially, more preferred below 1.0° radially, but even smaller side clearance angles are within the scope of the present invention, such as below 0.5° or even negative radially. Optionally the side clearance on opposite sides can be the same or different. Such low side clearance angles creates a tooth face with opposite sides being as close to parallel as possible, such as having a maximum deviation from parallel of 0.10mm per mm of the tooth tip, such as of a hard material tipping if present, but with even lower maximum deviations being preferred.

[0089] The present invention also concerns a band saw blade comprising the band saw tooth described in detail above.

[0090] Band saw blades or frame saw blade having just one saw tooth are not excluded within the scope of the present invention, however typical such saw blades may have many saw teeth of the same kind, or the band saw tooth of the present invention may be arranged in alternating combinations with known band sawteeth or alternating with saw teeth of different geometries within the scope of the present invention.

[0091] The band saw blade or the frame saw blade of the present invention may have set band saw teeth of any conventional kind of setting.

[0092] The band saw teeth or the frame saw teeth of the present invention can be provided with any band saw tooth height, band saw tooth pitch, Tooth Per Inch, gauge, gullet geometry, and gullet depth.

[0093] A modified saw tooth of the present invention may be created based on a conventional tooth with one tooth face part or two or more parallel tooth face parts offset each other by intermediate steps. Such a modified saw tooth may have a very low back angle of e. g. less that 2°, and a tooth back provided with opposite chamfers parallel to the blade back or parallel to at least a part of the tooth back, wherein the chamfer (s) closest to the tooth tip has / have an angle of less than 5°, or of less than 4°, of less than 3°, of less than 2°, of less than 1°.

[0094] The present invention also concerns band saw blades comprising the band saw tooth described in detail above wherein the first hook angle is higher than 38°, or higher than 39°, or higher than 40°.

[0095] The present invention also concerns the use of a band saw blade or frame saw blade comprising one or more saw teeth as described above for cutting wood.

[0096] The present invention also concerns the use of a band saw blade or a frame saw blade comprising one or more saw teeth asdescribed above wherein said saw blade undertakes a linear movement through the workpiece.

[0097] The present invention will be described below with references to the drawing in which:

[0098] Fig. 1 is a perspective side view of a fragment of a first embodiment of a band saw blade with a first embodiment of a band saw tooth according to the present invention,

[0099] Fig. 2 shows the same from the side,

[0100] Fig. 3 is an enlarged scale view of the encircled detail of fig. 2,

[0101] Fig. 4 is a fragmentary enlarged scale view of the tooth tip of the band saw tooth seen in figs. 1, 2 and 3,

[0102] Fig. 5 is a perspective view of a fragment of a second embodiment of a band saw blade with a second embodiment of a band saw tooth according to the present invention, and where the band saw tooth has a tooth tip enforced with a hard material tipping,

[0103] Fig. 6 shows the same from the side,

[0104] Fig. 7 is an enlarged scale front view at the tooth face of the hard material enforced tooth tip of the second embodiment of the band saw tooth seen in figs. 5 and 6,

[0105] Fig. 8 is an enlarged scale top view of the same seen from above,

[0106] Fig. 9 is an enlarged scale front view at a tooth face of a third embodiment of a band saw tooth according to the presentinvention, which third embodiment of a band saw tooth has opposite chamfers following the tooth back,

[0107] Fig. 10 is an enlarged scale view of the same seen from above,

[0108] Fig. 11 is an enlarged scale front view at a tooth face of a fourth embodiment of a band saw tooth according to the present invention, which fourth embodiment of a band saw tooth has opposite chamfers following the blade back,

[0109] Fig. 12 is an enlarged scale view of the same seen from above,

[0110] Fig. 13 shows schematically, in a side view, a fragment of a fifth embodiment of a band saw tooth according to the present invention,

[0111] Fig. 14 is an enlarged scale view of the encircled fragment of the fifth embodiment of a band saw tooth seen in fig. 13,

[0112] Fig. 15 shows schematically, in a side view, a fragment of a sixth embodiment of a band saw tooth according to the present invention,

[0113] Fig. 16 is an enlarged scale view of the encircled fragment of the sixth embodiment of a band saw tooth seen in fig. 15,

[0114] Fig. 17 shows schematically, in a side view, a fragment of a seventh embodiment of a band saw tooth according to the present invention,

[0115] Fig. 18 is an enlarged scale view of the encircled fragment of the seventh embodiment of a band saw tooth seen in fig. 17, and

[0116] Fig. 19 is a comparative cutting test between a band saw blade having conventional teeth with parallel first and second toothfaces and the band saw blade with the fourth embodiment of a band saw tooth of figs. 11 and 12.

[0117] The invention is described below by way of example with reference to a band saw blade. It is emphasized that this should not be construed as limiting the scope of the present inventions as the teeth of said inventions can be implemented in any kind of saw blade making a linear movement during cutting through a workpiece, including a frame saw.

[0118] Furthermore below the first tooth face part is discussed as the upper tooth face part, the first hook angle as the upper hook angle, the second tooth face part as the lower tooth face part, and the second hook angle as the lower hook angle, with reference to the orientation of the saw teeth in use. It should be noted that a tooth of the present invention can have several further tooth faces interposed between the upper tooth face and the lower tooth face.

[0119] For illustrative purposes, and to emphasize the relations between respective tooth face, tooth face parts, and associated angles, the interior and exterior angles between the respective tooth face part, intermediate tooth steps, and tooth face part are shown in figures 1 - 4 without any curvature, chamfer, setting and tipping.

[0120] Sharp-edged embodiments are within the scope of the present invention, but curved and / or chamfered faces of parts of the band saw teeth of the present invention may be preferred. The radius of curvature of interior and exterior angles depends on amongst other the available grinding head, the purpose of the band saw blade or the frame saw blade, and the material of said saw blades.Figs. 1 - 4 show an exemplary first embodiment of a band saw blade 1a with a first embodiment of band saw teeth 2a according to the present invention.

[0121] The fragment of the band saw blade 1a seen in fig. 1 has five identical novel band saw teeth 2a. The band saw teeth 2a protrude from a saw blade back 3a having a saw blade back line 3a' in parallel with a longitudinal axis of said blade back 3a, and associated gullets 4a in-between said band saw teeth 2a. The hatching 17a in fig. 2 illustrates the maximum volume that the band saw tooth 2a potentially can accommodate with regard to saw chips and saw dust during cutting.

[0122] The encircled band saw tooth 2a in fig. 2 has a tooth tip 5a, which tooth tip 5a has a tooth back 8a, a free tip edge 6a, and an overall tooth face 7a.

[0123] The free tip edge 6a of the tooth tip 5a extends into an upper tooth face part 9a having an upper tooth face 10a. The upper tooth face part 9a extends via an intermediate tooth step 11a with an intermediate tooth face 12a into a lower tooth face part 13a with a lower tooth face 14a, which lower tooth face part 13a extends into the gullet 4a. The upper tooth face part 9a, the intermediate tooth step 11a and the lower tooth face part 13a together expose the overall tooth face 7a for cutting through a wooden workpiece (not shown). The lower tooth face 14a is offset the upper tooth face 10a by the depth D of the intermediate tooth step Ila. As shown in fig. 3 the upper tooth face part 9a has a length C that is shorter than the height B of the lower tooth face part 13a.

[0124] The upper tooth face part 9a and the lower tooth face part 13a have different positive upper and lower hook angles, β and γ respectively, thus the upper tooth face 10a and the lower tooth face 14a are not parallel.As illustrated best in fig. 4 the upper tooth face part 9a has a positive upper hook angle β, which is higher than the positive lower hook angle γ of the lower tooth face part 13a. The intermediate tooth face 12a of the intermediate tooth step 11a, protrudes in this exemplary first embodiment of a band saw tooth 2a according to the present invention substantially perpendicular from the upper tooth face part 9a. As the positive upper hook angle β is higher than the positive lower hook angle γ, said positive upper hook angle β can be made even higher than hitherto practically possible without compromising the stability of the band saw tooth 2a when it cuts. In the first embodiment of a band saw tooth 2a seen in figs. 1 - 4 the back angle φ is 10°, the sharpness angle ω is 40°, the upper hook angle β is 40°, and the lower hook angle γ is 27°.

[0125] The upper tooth face part 9a initially attacks the workpiece. As the upper hook angle β is higher than upper hook angles of the prior art band saw teeth the upper tooth face part 9a is turned closer towards the gullet 4b than corresponding upper tooth face parts of the prior art band saw teeth, and the upper tooth face part 9a leans substantially forward to break into the wood fibers. The result is an improved efficient cutting effect. The initial cutting may be assisted by the lower tooth face part 13a, which cleans the cut through the wooden workpiece. Any irregularities in the workpiece can be attacked and processed in a neat cutting operation by the same inventive band saw tooth 2a, even during knots.

[0126] A high positive upper hook angle β with increased length of the upper tooth face 10a locates the deepest point of the upper tooth face part 9a deeper into the tooth tip 5a than the corresponding deepest point of a conventional band saw tooth. The intermediate tooth step 11a becomes substantially retracted from the free tip edge 6a, and the upper tooth face10a meets the workpiece substantially before the lower tooth face 14a enters the workpiece during cutting. The positive high upper hook angle β decreases the required cutting force, reduces creation of frictional heat, and cutting requires less power consumption.

[0127] The upper tooth face 10a may have a length C of just 5 mm. The lower tooth face 14a may be longer than the upper tooth face 10a. The short upper tooth face part 9a provides a very strong and durable band saw tooth 2a.

[0128] Fig. 5 shows, in perspective, a fragment of an exemplary second embodiment of a band saw blade lb with a second embodiment of a band saw tooth 2b according to the present invention. Figs. 6, 7 and 8 show the same in different views.

[0129] The second embodiment of a band saw blade lb with the second embodiment of band saw teeth 2b has a modification of the first embodiment of band saw teeth 2a, and for like parts same reference numerals are used, except that the annotation "a" is substituted by the annotation "b".

[0130] The second embodiment of a band saw blade lb has a blade back 3b with a saw blade back line 3b', band saw teeth 2b and gullets 4b in-between said band saw teeth 2b. The tooth tip 5b has an upper tooth face part 9b, one curved intermediate tooth step 11b, and a lower tooth face part 13b, which together expose a combined tooth face 7b. Further the band saw tooth 2b has a tooth back 8b, a free tip edge 6b, and a hard material tipping 18b.

[0131] An intermediate tooth step 11b is retracted from the free tip edge 6b, and the free tip edge 6b leans more forward compared to prior art cutting edges.The second embodiment of a band saw blade lb has a tooth pitch TP of 40mm, a tooth height TH of 14mm, a cut per tooth CT of 1.4mm, and a tooth capacity of 335mm2. The positive upper hook angle β' is 45°, the positive lower hook angle γ' is 25°, the back angle φ' is just 2°, and the sharpness angle ω' is 43°. The curved intermediate tooth step 11b has a radius of curvature R1 of 1.49 mm. The band saw tooth 2b may be particular suited for cutting cedar wood and pine wood. It is however emphasized that the aforementioned dimensions are just examples and shall not be construed as limiting the present invention.

[0132] Fig. 7 is an enlarged scale front view at the tooth face of the hard material enforced tooth tip 5b of the second embodiment of the band saw tooth 2b seen in figs. 5 and 6. The hard material used for tipping of the band saw tooth 2b is e. g. Stellite or carbide. The upper tooth face part 9b tapers vertically at an angle CX1 slightly towards the curved intermediate tooth step 11b. Thus the opposite sides of the upper tooth face part 9b converge slightly downwards towards the curved intermediate tooth step 11b. In the present exemplary embodiment the angle CX1 is 0.4°. Said curved intermediate tooth step 11b extends into the lower tooth face part 13b that tapers slightly vertically towards the gullet 4b.

[0133] Fig. 8 is an enlarged scale top view of the same seen from above, and as illustrated at angle α2 the opposite lengthwise extending sides 15b, 15b' along the tooth back 8b of the tooth tip 5b diverges in relation to the longitudinal axis of the blade back 3b, and thus in relation to the saw blade back line 3b'. The tooth tip 5b is wider than the blade back 3b whereby the angle α2 provides a side clearance on both sides of the blade back 3b, which side clearance provides a width of the kerf that reduces friction between saw blade lb and theadjacent cut sides of the wood being cut. In the present exemplary embodiment the angle α2 is 3°.

[0134] Fig. 9 is an enlarged scale front view at a tooth face 7c of a third embodiment of a band saw tooth 2c according to the present invention, and fig. 10 is an enlarged scale view of the same seen from above.

[0135] The third embodiment of a band saw tooth 2c is a modification of the second embodiment of a band saw tooth 2b and for like parts same reference numerals are used, except that the annotation "b" is substituted by the annotation "c".

[0136] The third embodiment of a band saw tooth 2c differs from the second embodiment of a band saw tooth 2b in that the opposite lengthwise extending sides 15c, 15c' of the tooth tip 5c have chamfers 16c, 16c' following at least a part of the tooth back 8c, as seen best in fig. 10. The chamfers 16c, 16c' are at an angle μ of 45° in relation to the plane of the blade back 3c, and as the chamfers 16c, 16c' follow the tooth back 8c they works similar to the tooth back 8c.

[0137] Fig. 11 is an enlarged scale front view at a tooth face 7d of a fourth embodiment of a band saw tooth 2d according to the present invention. Fig. 12 is an enlarged scale top view of the same seen from above

[0138] The fourth embodiment of a band saw tooth 2d is a modification of the third embodiment of a band saw tooth 2c and for like parts same reference numerals are used, except that the annotation "c" is substituted by the annotation "d".

[0139] The fourth embodiment of a band saw tooth 2d differs from the third embodiment of a band saw tooth 2c in that it has chamfers 16d, 16d' aligned with and following the blade back 3d instead of the curvature of the tooth back 8d..The width of the chamfers 16d, 16d are largest towards the free tooth edge 6d and tapers along the tooth back, as seen best in fig. 12. As long as the chamfers 16d, 16d' are angled below the back angle of the back of the tooth tip 5d they will act as a brake to create resistance against self-pulling of the band saw tooth 2d into the wood during cutting. Thereby can be obtained a stable cutting performance, as well as longer life time of the band saw teeth 2d.

[0140] Within the scope of the present invention the chamfers can be any angle μ, and are not limited to 45°. By adjusting the angle μ the chamfers may act as accelerators or decelerators as earlier described.

[0141] Fig. 13 shows a fifth embodiment of a band saw tooth 2e of the present invention, which band saw tooth 2e is a modification of the first embodiment of a band saw tooth 2a. For like parts the annotation "a" has been replaced with the annotation "e". The fifth embodiment of a band saw tooth 2e differs only in that the tooth back 8e has a plateau 20e spaced from the free tip edge 6e and a back angle φ''. The plateau 20e is located a distance E below a line parallel to the saw blade back line 3e' of the corresponding band saw blade le and extends through the free tip edge 6e, as seen best in the enlarged scale view of fig. 14 of the encircled detail seen in fig. 13.

[0142] Figs. 15 and 16 show a sixth embodiment of a band saw tooth 2f of the present invention, which band saw tooth 2f is yet a modification of the first embodiment of a band saw tooth 2a. For like parts the annotation "a" has been replaced with the annotation "f". The sixth embodiment of a band saw tooth 2f differs in that the tooth back 8f has an upright protrusion 19f spaced from the free tip edge 6f and a back angle φ'' '. The apex of the upright protrusion 19f is located a distance E'below a line parallel to the saw blade back line 3f ' of the band saw blade 1f and extends through the free tip edge 6f.

[0143] Both the plateau 20e and the upright protrusion 19f serve as a "cut per tooth limiter" that, optionally together with the low back angle of the present invention, prevents the band saw blade from being pulled off the pulley wheels and the band saw teeth 2e; 2f from pulling the wooden workpiece, such as timber, uncontrolled into the band saw blade 1e; 1f and therefore keep the cutting process stable when cutting with high positive hook angles. The configuration of the plateau and the upright protrusion thus has influence on cut per tooth of the band saw tooth 2e; 2f through the wood and contributes in preventing excessive self-pulling of the band saw tooth 2e; 2f of the blade 1e; 1f into the wood.

[0144] Emphasis is made than any of the band saw teeth described herein can be provided with a similar "cut per tooth limiter" at its tooth back. The distance to the free tip edge 6e; 6f and the height of the "cut per tooth limiter", thus of the upright protrusion 19f and of the position of the plateau 20e, can vary according to need and intended use of the band saw blades.

[0145] Fig. 17 shows schematically a fragment of a seventh embodiment of a band saw tooth 2g according to the present invention. Fig.

[0146] 18 shows, in an enlarged scale view, the encircled fragment of the seventh embodiment of a band saw tooth 2g seen in fig. 14. The seventh embodiment of a band saw tooth 2g is a modification of the first embodiment of a band saw tooth 2a. For like parts the annotation "a" has been replaced with the annotation "g".

[0147] The seventh embodiment of a band saw tooth 2g differs from the first embodiment of a band saw tooth 2a in that it has a sequence of two intermediate tooth steps, a first intermediate tooth step 11g and a second intermediate tooth step 11g' spaced from each other by an intermediate tooth face part 21g. Thefirst intermediate tooth step 11g extends at a substantially right interior first angle from the upper tooth face part 9g, and then bends at an exterior right first angle into the intermediate tooth face part 21g, that has an intermediate tooth face 22g that is parallel to the upper tooth face 10g. Accordingly, the intermediate tooth face 22g and the upper tooth face 10g both have the same upper hook angle β', but said hook angles could be different. Preferably the uppermost upper hook angle β' should be the highest. The intermediate tooth face part 21g extends via an interior blunt second angle into the second intermediate tooth step 11g'. The second intermediate tooth step 11g' extends via an exterior blunt second angle into the lower tooth face part 13g that has the lower hook angle γ'. The lower tooth face part 13g extends into the gullet 4g.

[0148] The upper tooth face part 10g, the lower tooth face 14g, the first intermediate tooth face 12g of the first intermediate tooth step 11g, and the second intermediate tooth face 12g' of the second intermediate tooth step 11g' may, or may not, all be part of the cutting zone, which cutting zone may extend about 10 mm from the free edge tip 6g.

[0149] Fig. 19 shows photos of a comparative cutting test. To the right in fig. 19 is seen a test specimen resulting from cutting with a band saw blade having conventional teeth with parallel upper and lower tooth faces, where the upper hook angle is 27°. The cut surface is highly uneven, frayed and with bristled wood fibers. In particular at the bottom right corner is seen how rough the cut is, and that the cut surface is very open and has an uneven structure.

[0150] To the left in fig. 19 is seen a test specimen resulting from a cut with a band saw blade Id having the fourth embodiment of band saw teeth 2d, as discussed in relation to figs. 11 and 12.The cut surface is very smooth, with minimum fraying and minimum bristled wood fibers.

[0151] The present invention does encompass embodiments and variations of band saw teeth where the first and lower hook angle, the lengths of the upper tooth face part, and of the intermediate tooth face, and of the lower tooth face part can differ from the exemplary configurations discussed above and shown in the figures. Any tooth of the present invention, including those shown in the figures, may have one or more of chamfers, plateaus, upright protrusions, hard material tipping and any curvature of the gullet, in any appropriate combination.

[0152] It is emphasized that within the scope of the present invention a tooth face can be stepped. In this context it is the plane of the overall tooth face is created of small steps that define the corresponding hook angle.

[0153] Thus within the scope of the present invention the figures should not be seen as limiting, and modifications of the shown and discussed band saw tooth geometries and profiles are encompassed.

Claims

Claims1. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw comprising at least a first tooth face part (9a; 9b; 9c; 9d; 9e; 9f; 9g) arranged at first hook angle (β;β') and a second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) arranged at a second hook angle, characterised in that the first hook angle (P; P' ) is different from the second hook angle (y; y' ).

2. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 1, characterised in that the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) is an upper tooth face part, and optionally the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) is a lower tooth face part arranged below the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g).

3. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claims 1 or 2, characterised in that the first hook angle (β;β') is higher than or equal to 36°.

4. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of claims 1, 2 or 3, characterised in that both the first hook angle (β;β') and the second hook angle (γ;γ') are positive.

5. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the first hook angle (β;β') is higher than or equal to 37°, or higher than or equal to 38°, or higher than or equal to 39°, or higher than or equal to 40°, or higher than or equal to 41°, or higherthan or equal to 42°, or higher than or equal to 43°, or higher than or equal to 43°, or higher than or equal to 44°, or higher than or equal to 45°, or higher than or equal to 46°, or higher than or equal to 47°, or higher than or equal to 48°, or higher than or equal to 49°, or higher than or equal to 50°; more preferred the upper hook angle (β;β') is 45°.

6. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the first hook angle (β;β') is higher than the second hook angle (γ;γ').

7. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of any of the preceding claims, characterised in that the second hook angle (γ;γ') is at least 12.1°.

8. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the first tooth face part (10g; lOh) has a positive first hook angle (β;β'), and the second tooth face part (14g;14g) has a zero or negative second hook angle (γ'').

9. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) has a length that is equal to or longer than the length of the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g).

10. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the length of the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) and / or the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) is minimum 1 mm.

11. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) and the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) are offset each other by an intermediate tooth step (Ila; 11b; He; lid; He; Ilf; 11g).

12. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 11, characterised in that the intermediate tooth step (Ila; 11b; 11c; lid; lie; Ilf; 11g) is curved or straight.

13. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claims 11 or 12, characterised in that said tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) comprises more than one intermediate tooth step (Ila; 11b; 11c; lid; lie; Ilf; 11g; llh; Hi; 11 j; 11 j ' ) in extended sequence in-between the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) and the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g).

14. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of claims 11, 12, or 13, characterised in that the number of intermediate tooth steps (Ila; 11b; 11c; lid; He; Ilf; 11g; llh; Hi; 11 j; 11 j ' ) is at least 2, 3, 4, 5, or 6, wherein the intermediate tooth steps ( 1 lb; 11c; 1 Id; 1 le; 1 If; 11g; 1 Ih; 1 li; 11 j; 11 j ' ) have same or different angling, and a preferred length of less than 3 mm, or less than 2 mm or less than 1 mm.

15. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims 11 - 14, characterised in that the at least one intermediate tooth step extends into a third tooth face part in form of a third section (31g) having a positive third hook angle (ε).

16. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that a free tip edge ( 6b; 6c; 6d; 6e; 6f; 6g; 6h; 6i ) of the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or tooth of a frame saw is arranged protruding beyond, or is in, the plane of the second tooth face part (14b; 14c; 14d; 14e; 14f; 14g; 14h; 14i) seen in a cutting direction of the saw blade.

17. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that a tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or the tooth of a frame saw is inclined in relation to a blade back (3a; 3b; 3c; 3d; 3e; 3f; 3g), optionally said tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) is curved or straight, preferably the tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) has a back angle (Cp; (p'; (p"; (p" ' ) 1 ess than or equal to 10°, more preferably said back angle (cp; cp'; cp' '; cp' ' ' ) is less than or equal to 8°, more preferred said back angle (cp; cp'; cp' '; cp' ' ' ) is less than or equal to 5°, even more preferred said back angle (Cp; (p'; (p"; (p" ' ) is 1 ess than or equal to 4°, even more preferred said back angle (cp; cp'; cp' '; cp' ' ' ) is less than or equal to 3°, or less than or equal to 2°, or less than or equal to 1°.

18. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 17, characterised in that the tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) has an upright protrusion (19f) or a plateau (20e) spaced from a free tip edge ( 6a; 6b; 6c; 6d; 6e; 6f; 6g) of a tooth tip (5a; 5b; 5c; 5d; 5e; 5f; 5g).

19. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of claims 17 or 18, characterised in that the degree of the back angle (Cp; (p'; (p"; (p" ' ) is determined based on the relation between an intended thickness of a saw chip and a distance between the free tip edges ( 6a; 6b; 6c; 6d; 6e; 6f; 6g) of two consecutive tooth tips (5a; 5b; 5c; 5d; 5e; 5f; 5g).

20. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in comprising a hard material tipping (18b).

21. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 20, characterised in that the hard material is selected from the group comprising one or more of Stellite, ceramics, carbide, or CBN.

22. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims 17 - 21, characterised in that at least a length of the tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) closest to a first tooth face (10a; 10b; 10c; lOd; lOe; lOf; 10g) of the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) has a chamfer ( 16c, 16c'; 16d; 16d' ), preferably both sides (15c, 15c'; 15d; 15d') of the tooth back (8a; 8b; 8c; 8d; 8e; 8f; 8g) have chamfers ( 16c, 16c'; 16d; 16d' ), which chamfers ( 16c, 16c'; 16d; 16d' ) are the same or different.

23. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 22, characterised in that the chamfer ( 16c, 16c'; 16d; 16d' ) extends in the longitudinal direction of a band saw blade (la; lb; 1c; Id; le; If; 1g) or of a blade of a frame saw, and has an orientation selected fromparallel to the blade back (3a; 3b; 3c; 3d; 3e; 3f; 3g) of said saw blade (la; lb; 1c; Id; le; If; 1g),following the curvature of at least a part of tooth back of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or the tooth of a frame saw;and / or opposite chamfers ( 16c, 16c'; 16d, 16d' ) are mirror- shaped.

24. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims 17 - 23, characterised in that the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or the tooth of a frame saw has side clearance in relation to the blade back (3a; 3b; 3c; 3d; 3e; 3f; 3g), which side clearance is on one side ( 15c, 15c'; 15d; 15d' ) of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or on opposite sides ( 15c, 15c'; 15d; 15d' ) of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or of the tooth of a frame saw.

25. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to claim 24, characterised in that a side clearance angle (μ;μ') of the side clearance is below 1.5° radially, more preferred below 1.0° radially, more preferred below 0.7° radially, more preferred below 0.5° radially; and optionally the side clearance on opposite sides (15c, 15c'; 15d; 15d' ) of the band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or of the tooth of a frame saw is the same or different.

26. A band saw tooth (2a; 2b; 2c; 2d; 2e; 2f; 2g) or a tooth of a frame saw according to any of the preceding claims, characterised in that the first tooth face part ( 9a; 9b; 9c; 9d; 9e; 9f; 9g) and the second tooth face part (13a; 13b; 13c; 13d; 13e; 13f; 13g) are not parallel.

27. A band saw blade (la; lb; 1c; Id; le; If; 1g) or frame saw blade comprising one or more band saw teeth (2a; 2b; 2c; 2d; 2e; 2f; 2g) according to any of the preceding claims, wherein the band saw teeth (2a; 2b; 2c; 2d; 2e; 2f; 2g) are of the same kind, of combined with a different kind of band saw teeth, optionally the band saw teeth (2a; 2b; 2c; 2d; 2e; 2f; 2g) are set, optionally swaged.

28. A band saw blade (la; lb; 1c; Id; le; If; 1g; Ih; li; 1 j ) or frame saw blade according to claim 27, characterised in that the first hook angle (P; P' ) is higher than 38°, preferably higher than 40°.

29. Use of a band saw blade or a blade of a frame saw comprising one or more teeth (2a; 2b; 2c; 2d; 2e; 2f; 2g) according to any of the preceding claims 1 - 26 for cutting wood.

30. Use of a band saw blade or a blade of a frame saw comprising one or more teeth (2a; 2b; 2c; 2d; 2e; 2f; 2g) according to any of the preceding claims 1 - 26 on a saw that undertakes a linear movement through the workpiece.

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