Cicular Saw Blade

Abstract

A long metal sheet is rolled in a width direction to form a hollow tube while being delivered. A seam appeared in a longitudinal direction of a tubular body is electrically welded to form an electric-resistance-welded tube. The electric-resistance-welded tube is cut in a predetermined size by a circular saw cutting machine which travels in synchronicity with the electric-resistance-welded tube during its production process. A weld bead remains at the seam of the electric-resistance-welded tube so that the weld bead remained in the tube may be involved when the electric-resistance-welded tube is cut by the circular saw blade. Therefore, there is a problem to be solved that a significant load may be generated on a second rake face of the tip when the cutting tip of the circular saw blade bites debris in the tube, which may lead to the chipping or missing of the tips.

Solution to Problem

A circular saw blade has a plurality of cutting tips 10 joined at an outer circumference of a base metal. Each of the cutting tips 10 includes a first rake face 14 located at a front of the tip of the circular saw blade in a rotation direction of the circular saw blade, a flank 18 located in an outer circumferential direction of the circular saw blade, and a second rake face 22 adjacent to the first rake face 14 on a side of an axis of the circular saw blade. The center of the second rake face 22 is configured to project in the rotation direction of the circular saw blade.

Claims

1. A circular saw blade including a plurality of cutting tips positioned along at an outer circumference of a base metal, each of the cutting tips comprising: a first rake face positioned at a front of the cutting tip relative to a rotation direction of the circular saw blade; a flank defining a first cutting edge at an intersection with the first rake face, wherein the flank is positioned at an outer circumferential side of the cutting tip; and a second rake face positioned at the front of the cutting tip relative to the rotation direction of the circular saw blade, wherein the second rake face is adjacent to the first rake face on a side of an axis of the circular saw blade, wherein a center of the second rake face projects forward relative to the rotation direction of the circular saw blade.

2. The circular saw blade of claim 1, wherein the second rake face defines a second cutting edge at an intersection with the flank.

3. The circular saw blade of claim 1, wherein the second rake face is inclined from the center of the second rake face to right and from the center of the second rake face to the left, and wherein face bevel angles of the second rake face range from 2° to 50°.

4. The circular saw blade of claim 1, wherein the flank is divided into a plurality of sections by a release groove or a top bevel angle formed in the flank in a rotational axis direction of the circular saw blade.

5. A circular saw blade, comprising: a plurality of cutting tips positioned at an outer circumference of a base metal, wherein each of the plurality of cutting tips comprises: a flank located on an upper side of the cutting tip, wherein the upper side of the cutting tip faces away from an axis of rotation of the circular saw blade, and a second rake face formed on a front side of the cutting tip, wherein the front side of the cutting tip faces forward relative to a rotational direction of the circular saw blade, wherein the second rake face projects further forward than the flank in the rotational direction of the circular saw blade, and wherein a center portion of the second rake face in a direction parallel to the axis of rotation of the circular saw blade projects further forward relative to the rotational direction of the circular saw blade than lateral side edges of the second rake face.

6. The circular saw blade of claim 5, wherein the center portion of the second rake face is a flat surface section.

7. The circular saw blade of claim 6, wherein a length of the flat surface section in the direction parallel to the axis of rotation of the circular saw blade is 1 mm or less.

8. The circular saw blade of claim 5, wherein an uppermost portion of the center portion of the second rake face is spaced away from the flank.

9. The circular saw blade of claim 8, wherein an uppermost portion of the of the second rake face spaced apart from the center portion of the second rake face intersects the flank to form a cutting edge.

10. The circular saw blade of claim 5, wherein an upper most portion of the center portion of the second rake face is positioned nearer to the axis of rotation of the circular saw blade than an uppermost portion of the flank.

11. The circular saw blade of claim 5, further comprising a first rake face positioned between the center portion of the second rake face and the flank in a radial direction of the circular saw blade, wherein the radial direction is perpendicular to the axis of rotation of the circular saw blade.

12. The circular saw blade of claim 11, wherein lateral side edges of the first rake face project further forward than the lateral side edges of the second rake face relative to the rotational direction of the circular saw blade.

13. The circular saw blade of claim 5, wherein the second rake face comprises first and second surfaces positioned on opposite sides of the center portion of the second rake face in the direction parallel to the axis of rotation of the circular saw blade.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1(a) is a plan view of a cutting tip according to an exemplary embodiment of the present invention. FIG. 1(b) is a front view showing a second rake face of the tip. FIG. 1(c) is a side view of an entire circular saw blade.

[0013] FIG. 2 is an enlarged view of a flank of the cutting tip shown in FIG. 1(a). FIG. 2 illustrates the first rake face is formed in a triangular shape.

[0014] FIG. 3 is an enlarged view of the first rake face and the second rake face of the cutting tip shown in FIG. 1(b). FIG. 3 illustrates the first rake face is in the center and is formed in a triangular shape.

[0015] FIG. 4 is a perspective view of a cutting tip according to an exemplary embodiment illustrating a projection of the second rake face inclined to the right and left with a flat section interleaved in the center.

[0016] FIG. 5(a) is a plan view of the cutting tip according to a second exemplary embodiment of the present invention. FIG. 5(b) is a front view of the second rake face of the tip.

[0017] FIG. 6(a) is a plan view of a cutting tip according to a third exemplary embodiment of the present invention. FIG. 6(b) is a front view of the second rake face of the tip.

[0018] FIG. 7(a) is a plan view of a cutting tip according to a fourth exemplary embodiment of the present invention. FIG. 7(b) is a front view of the second rake face of the tip.

[0019] FIGS. 8(a) to 8(d) illustrate polygonal first rake faces formed on the cutting tips according to exemplary embodiments. FIG. 8(a) is a triangular (fan shaped) first rake face. FIG. 8(b) is a rectangular first rake face. FIG. 8(c) is a pentagonal first rake face. FIG. 8(d) is a hexagonal first rake face.

[0020] FIG. 9(a) is an enlarged side view of a cutting tip for a circular saw blade. FIG. 9(b) is a front view illustrating a rake face of the cutting tip. FIG. 9(c) is a plan view of a flank of the cutting tip.

[0021] FIGS. 10(a) and 10(b) are cross-sectional views illustrating phases during cutting an electric-resistance-welded tube with a traveling-type circular saw cutting machine. FIG. 10(a) illustrates a state where a bead remains on a bottom and within the tube. FIG. 10(b) illustrates a state where the bead has been bitten into by the second rake face of the cutting tip while the bead is held to an inner wall of the tube.

[0022] FIG. 11 is a perspective view of the cutting tip shown in FIG. 9, in which spots on both sides of the second rake face serve as stress concentration spots due to the biting of the bead.

DESCRIPTION OF EMBODIMENTS

[0023] Hereinafter, exemplary embodiments of cutting tips joined to a circular saw blade according to the present invention will be described with reference to the drawings. The above-described electric-resistance-welded tube is considered to be an object to be cut (workpiece) with the circular saw blade according to the exemplary embodiments. However, another workpiece made of a different material, such as, for example, high tensile steel, may also be considered to be an object to be cut.

[0024] First, FIG. 1(a) is a plan view of a cutting tip 10 according to an exemplary embodiment. The cutting tip 10 is joined to a circular saw blade, as shown in FIG. 1(c). FIG. 1(b) is a front view illustrating a second rake face 22 of the tip 10. As shown in FIGS. 1(a) and (b), the second rake face 22 of the cutting tip 10 of the exemplary embodiment defines second cutting edges 52 on both sides at an intersection line with a flank 18. As also shown in FIGS. 1(a) and 1(b), the second rake face 22 of the cutting tip includes a projection 30 formed by allowing the center of the second rake face 22 to slightly project forward in the rotation direction of the circular saw blade. The projection 30 is formed as projecting from the center of the second rake face 22, so that the second rake face 22 in an inclined state to the left and right, as illustrated in FIG. 2. FIG. 2 shows an enlarged first rake face side of the flank 18. Right and left face bevel angles α shown in FIG. 2 range from 2° to 50°. A first rake angle ranges from −30° to 0°, and a second rake angle from −5° to 10°. Further, when the first rake angle is chamfered between the flank 18 and a lateral side as shown in FIGS. 1(a) and (b), a ridge line between the chamfered face and a rake face defines a cutting edge. If that rake face is the second rake face 22, the cutting edge forms a part of the second cutting edge 52.

[0025] Various experiments were conducted on the face bevel angles α inclined to the right and left on the second rake face 22 to find appropriate ranges for the angles. More specifically, the face bevel angles α were changed to 0°, 2°, 7°, 30°, and 50° and an electric-resistance-welded tube was cut. As the electric-resistance-welded tube was cut, an impact and other stresses applied to the second rake face 22 of the cutting tip were analyzed step by step. During these tests, a stress concentration scar a was generated on the projection 30 in a location shown in FIG. 1(b) due to the impacts. This was observed every time the stress was analyzed. It was found that tip damage or chipping was unlikely to occur since the stress concentration scar a appears in the vicinity of the center of the projection 30 of the second rake face 22. This was observed at every analysis.

[0026] Considering the results of analysis, the change in stress applied to the second rake face 22 when the cutting tips start cutting while contacting the workpiece (the weld bead) and cut through the workpiece was found to be well balanced and favorable if the face bevel angles α as measures in the vicinity of the center of the projection 30 fall in the range of equal to or greater than 7° and smaller than 30°. Compared to the cases where the face bevel angles α are 0° and 2°, an area of a stress concentration spot during cutting the workpiece was smaller in the case of 2°. It was also found that the risk of chipping would increase since an intense stress concentration occurs immediately after contacting the workpiece if the face bevel angles α exceeds 30°. However, even when the face bevel angles α are 2° or 50°, it was confirmed that the beneficial effect is sufficiently significant compared with conventional cutting tips with a flat second rake face 22.

[0027] As shown in FIG. 1(b), the projection 30 formed on the second rake face 22 of the cutting tip 10 of FIG. 1 is formed as one line at the intersection line between two faces inclined toward respective sides. However, as alternative exemplary embodiments, as shown in FIG. 4 to FIG. 7, the projection 30 may be formed not in a line between the right and left inclined faces, but formed to have a flat section or rounded section interleaved between inclined faces. For example, FIG. 4 is a perspective view of a cutting tip 10 as one exemplary embodiment. In this exemplary embodiment, the projection 30 of the second rake face 22 vertically projects forward in the rotation direction of the circular saw blade and projects at the center of the second rake face 22. In other words, the projection 30 inclines to the right and left with the flat section 22a interleaved at the center of the second rake face 22.

[0028] Further, the projection 30 of FIG. 5 is rounded while the projection 30 of FIG. 6 is flat. Furthermore, the projection 30 of FIG. 7 is flat and chamfered. Chipping of the edge may be more likely to occur when the edge bites into the weld bead 26 if a width in an edge thickness direction of a flat surface of the projection 30 exceeds 1 mm. However, it was found that the circular saw blade is capable of cutting well even when there is a weld bead 26 if the width of the flat surface of the projection 30 is equal to or narrower than 1 mm.

[0029] In the present invention, since the center of the second rake face 22 of the cutting tip 10 is allowed to protrude in the rotation direction of the circular saw blade, the flank 18 of the cutting tip 10 comes to be divided in a plurality of sections in a rotational axis direction of the circular saw blade. This results in the first rake face 14 of the cutting tip 10 to form a polygonal shape in the vicinity of the center as shown in FIG. 3. FIGS. 8 (a) to (d) illustrates the first rake face 14 having such a polygonal shape. More specifically, in FIG. 8 (a), the first rake face 14 is formed in a triangular shape (fan shape), and in FIG. 8 (b), the first rake face 14 is formed in a rectangular shape. In FIG. 8 (c), the first rake face 14 is formed in a pentagonal shape, while in FIG. 8 (d), the first rake face 14 is formed in a hexagonal shape.

REFERENCE SIGNS LIST

[0030] 10 cutting tip, 12 base metal, 14 first rake face, 16 first cutting edge, 18 flank, 22 second rake face, a face bevel angle, 52 second cutting edge