Abstract
A blade for a reciprocating saw, said blade being made from at least a bimetallic sheet material and comprising a flat body portion comprising a low-alloy steel material or a carbon steel material, a cutting edge portion comprising a high-speed steel material provided with a plurality of teeth arranged at a first edge of said flat body portion, and a back edge portion arranged at a second edge of said flat body portion opposite of said cutting edge portion, wherein said back edge portion is provided with a non-cutting micro-structured surface.
Claims
1. A blade for a reciprocating saw, said blade being made from at least a bimetallic sheet material and comprising a flat body portion comprising a low-alloy steel material or a carbon steel material, a cutting edge portion comprising a high-speed steel material provided with a plurality of teeth arranged at a first edge of said flat body portion, and a back edge portion arranged at a second edge of said flat body portion opposite of said cutting edge portion, wherein said back edge portion is provided with a non-cutting micro-structured surface.
2. The blade of claim 1, wherein said micro-structured surface comprises structures having a height between 10 and 450 m.
3. The blade of claim 1, wherein said micro-structured surface comprises structures having a height between 50 and 400 m.
4. The blade of claim 1, wherein said micro-structured surface comprises structures having a height between 100 and 300 m.
5. The blade of claim 1, wherein said micro-structured surface is an abrasive surface for deburring.
6. The blade of claim 5, wherein the micro-structured surface is provided with projections and depressions.
7. The blade of claim 6, wherein said projections are designed as non-cutting elements which exhibit no clearance angle.
8. The blade of claim 6, wherein said projections are designed as non-cutting elements wherein the leading and trailing edges of the projections exhibit an obtuse angle.
9. The blade of claim 6, wherein the length of the projections is comprised between 200 and 5000 m.
10. The blade of claim 1, wherein said blade is made from a trimetallic sheet material, said flat body portion comprising a low-alloy steel material or a carbon steel material, said cutting edge portion comprising a high speed steel material and said back edge portion comprising a tool steel material, such as a high speed steel material.
11. The blade of claim 1, wherein said micro-structured surface of said back edge portion is obtained by plastically deforming said surface using a metal forming technique.
12. The blade of claim 11, wherein said back edge portion has a tapered cross-section.
13. The blade of claim 1, wherein said micro-structured surface of said back edge portion is obtained by machining said surface.
14. The blade of claim 1, wherein said micro-structured surface of said back edge portion is obtained by adding material to said second edge of said flat body portion using an additive manufacturing technique.
15. The blade of claim 14, wherein said micro-structured surface of said back edge portion is obtained by partially embedding abrasive particles in said surface.
16. The blade of claim 15, wherein said abrasive particles are selected from tool steel particles, ceramic particles, hard metal particles or combinations thereof.
17. The blade of claim 16, wherein said hard metal particles are made from tungsten carbide, titanium carbide, or tantalum carbide.
18. The blade of claim 16, wherein said abrasive particles have an average size comprised between 15 and 500 m.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a side view of a saw blade for a reciprocating saw having a micro-structured surface.
[0033] FIG. 2 is a side view of an embodiment of a saw blade for a reciprocating saw according to the invention.
[0034] FIG. 3A is an enlarged detail of the back edge portion of the saw blade of FIG. 1.
[0035] FIG. 3B is an enlarged detail of the back edge portion of the saw blade of FIG. 2.
[0036] FIG. 4A shows a cross-sectional view of body portion and back edge portion of a saw blade from which the saw blade of FIG. 2 can be formed.
[0037] FIG. 4B shows a cross-sectional view of body portion and back edge portion of an alternative embodiment of FIG. 4A.
[0038] FIG. 4C shows a cross-sectional view of a body portion and a back edge portion of a further embodiment of FIG. 4A.
[0039] FIG. 4D shows a cross-sectional view of yet another embodiment of FIG. 4A.
[0040] FIG. 5A is a top view of the back edge portion of one embodiment of the invention.
[0041] FIG. 5b is a depth profile of the back edge portion of FIG. 5A.
[0042] FIG. 6A is a top view of the back edge portion of another embodiment of the invention.
[0043] FIG. 6B is a depth profile of the back edge portion of FIG. 6A.
[0044] FIG. 7A is a top view of the back edge portion of a further embodiment of the invention.
[0045] FIG. 7B is a depth profile of the back edge portion of FIG. 7A.
[0046] FIG. 8 shows the application of the saw blade of the present invention in deburring operation.
DETAILED DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 shows an exemplary embodiment of a saw blade 10 for a reciprocating saw having differently configured edges. Saw blade 10 comprises a flat body portion 11 extending on one and into a tang 12 for attaching the saw blade to a power tool. Tang 12 is provided with a conventional locking aperture 13. The body portion 11 has a first edge 14 at which a cutting edge portion 15 provided with teeth 16 is arranged. In the depicted embodiment, the teeth 16 are completely arranged within the cutting edge portion 15. It is, however, possible to arrange teeth 16 in such a manner that their teeth bases extend into the flat body portion 11 allowing the teeth to benefit both from the more flexible material of the flat body portion 11 and, at the teeth tips, from the harder material of the cutting edge portion 15. At a second edge 17 of the flat body portion 11, located opposite of the cutting edge portion 15, a back edge portion 18 of the saw blade is arranged. The back edge portion 18 is provided with a micro-structured surface 19. Accordingly, when operated in direction of arrow 20, the saw blade acts on a workpiece (not shown) as a cutting tool via its cutting edge portion 15. When operated in direction of arrow 21, the micro-structured back-edge portion 18 of blade 11 acts on the workpiece. As a can be taken from FIG. 1 and particularly from the enlarged view of FIG. 3A, a typical micro-structured surface 19 will exhibit sharp peaks 22 which can exhibit cutting or sawing properties when applied with force on to a workpiece.
[0048] FIG. 2 shows an exemplary embodiment of a saw blade 110 of the present invention. Saw blade 110 essentially corresponds to saw blade 10 depicted in FIG. 1 except that the micro-structured surface 119 of saw blade 110 exhibits a more regular surface structure. Elements, which correspond to elements already described in connection with the embodiment of FIG. 1 are denoted by the same reference signs and will not be described in detail again. As can be taken from FIG. 2, particularly in connection with the enlarged view of FIG. 3B, the micro-structured surface 119 of the blade of the present invention avoids peaks 122, which exhibit sharp points and/or points exhibiting a clearance angle. Consequently, the micro-structured surface 119 will not exhibit cutting or sawing properties. Rather, the micro-structured surface 119 provides both increased grip when handling the saw blade 10 and can act as deburring tool. Accordingly, when operated in direction of arrow 20, the saw blade acts as a cutting tool via its cutting edge portion 15. When operated in direction of arrow 21, blade 11 acts as a deburring tool via its micro-structured back edge portion.
[0049] FIGS. 3A and 3B are enlarged details of the back edge portion of the saw blade of FIGS. 1 and 2, respectively. As can be taken therefrom, the height h of the structures provided on the back edge portions 19, 119, respectively, are determined as the distance between peaks and adjacent valleys/bottoms of the structures. For instance, a height h in FIG. 3A corresponds to the distance between peak 22 and valley/bottom 23 while height h in the embodiment of FIG. 3B corresponds to the distance between peak 122 and valley/bottom 123. In the regular pattern of FIG. 3B, the height distribution is quite narrow, while the irregular surface structure of the embodiment of FIG. 3A exhibits a broader distribution of structure heights. Likewise, the radii of the curvature of the peaks in the embodiment of FIG. 3A exhibited large distribution of radii. Consequently, in this embodiment, a large number of peaks will be quite sharp and might even exhibit clearance angles so that conventional micro-structured surface will exhibit cutting or sawing properties. In contrast, the blade of the invention as shown in FIG. 3B has a micro-structured back edge portion which is specifically designed to avoid sharp peaks with cutting or sawing properties.
[0050] FIG. 4 shows four alternatives of cross-sectional views of the back edge portion and the flat body portion (partly) of the blade before the micro-structures are applied to the back edge portion. Accordingly, as shown in FIG. 4A, the back edge portion can have a rectangular profile 24. In another embodiment, as shown in FIG. 4B, the back edge portion has a rounded profile 25. FIG. 4C shows a further embodiment where the back edge portion has a tapering cross-section 26 having an edge which is smaller in width than the width of the flat body portion. In the embodiment of FIG. 4C, the sides 27, 28 and the top 29 of the back edge portion are straight/flat. FIG. 4D shows an alternative embodiment of a tapering back edge portion having a cross-section 30 where the sides 31, 32 of the back edge portion are concavely curved while the top 33 is flat.
[0051] FIGS. 5, 6 and 7 show exemplary embodiments of back edge portions of the blades according to the invention having a more regular micro-structured surface, i.e. similar to the embodiment of FIG. 2.
[0052] FIG. 5A is a microscopic photograph of a top view of the back edge portion of one embodiment of the invention where structures obtained by a regularly repeating pattern of projections 34 and depressions 35 having a typical height h of approximately 280 m are obtained by a metal-forming process such as embossing. The depressions 35 have a length L.sub.d of approximately 400 m while the projections have a length L.sub.p of approximately 600 m, determined at 50% of height h of the structure. As can also be taken from FIG. 5A, the projections are provided with an obtuse angle at their leading edges 36 and trailing edges 37, respectively, and do not exhibit a clearance angle. Accordingly, the projections can act as deburring elements. A corresponding depth profile measured along the black center line of FIG. 5A is depicted in FIG. 5B.
[0053] An alternative surface structure, also obtained by embossing, and a corresponding depth profile is depicted in FIGS. 6A and 6B, respectively. As can be taken therefrom, the structures of the micro-structured surface have a typical height of approximately 130 m. Again, the depth profile of FIG. 6B is obtained along the black center line of FIG. 6A.
[0054] Yet another alternative surface structure which is also obtained by embossing and its corresponding depth profile are depicted in FIGS. 7A and 7B, respectively. In this embodiment, the edge of the back edge portion comprises micro-structures having typical height of approximately 120 m. Two types of depressions 38, 39 and two types of projections 40, 41 are provided in a repeating pattern. The depressions 38, 39 are mirror images of each other and have a length L.sub.d of approximately 300 m each. The projections 40, 41 have different lengths and slightly different heights. The length L.sub.p1 of projections 40 is approximately 650 m, while the length L.sub.p2 of projections 41 is approximately 2000 m. The longer projection 41 acts as a support surface while the shorter projection 40 is slightly higher that projection 40 thus extending beyond the upper surface of projection 41 and acting as a deburring element. As can be seen from the depth profile of FIG. 7B, both projections 40 and 41 exhibit non-cutting obtuse-angled leading and trailing edges.
[0055] The micro-structured surfaces of the embodiments of FIGS. 5A, 5B and 6A, 6B are obtained from back edge portions exhibiting a rectangular cross-section as shown in FIG. 4A while the micro-structured surfaces of the embodiments of FIGS. 7A, 7B is obtained from a back edge portion exhibiting a taping cross-section as shown in FIG. 4D. As can be taken from the top view photographs of FIGS. 5A, 6A and 7A, respectively, the embossed depression obtained from the tapering back edge portion of the embodiment of FIG. 7A, 7B exhibit a lower degree of lateral broadening and do not extend beyond the width of the body portion of the blade.
[0056] FIG. 8 shows a schematic embodiment of a saw blade of the present invention in a deburring operation. The saw blade 50 is provided with a flat body portion 51, a cutting edge portion 52 having teeth 53 and a back edge portion 54 which exhibits are micro-structured surface 55 according to the embodiment of FIG. 7A, 7B. Accordingly, the micro-structured surface 55 is provided with two types of projections, namely shorter, slightly higher projections 40 which act as deburring elements and longer, slightly lower projections 41 which act as supporting elements (see also FIG. 7A). As shown in the FIG. 8, the saw blade 50 is applied to a workpiece 56 which has an edge 57 which exhibits a rough surface 58 as a result of a previous sawing operation of blade 50 with its cutting edge portion 52. The back edge portion 54 of blade 50 is used as a deburring tool by moving it over the rough surface 58 in the direction indicated by arrow 59 while simultaneously driving the saw blade 50 in reciprocating manner (indicated by arrow 60) in the longitudinal direction of the blade. The resulting surface 61 of edge 57 is free of burrs. Accordingly, with the blade of the present invention, the operator can saw and deburr the resulting cut in a single up- and down movement of the blade without requiring additional deburring tools.
