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.

Abstract: A circular saw blade to cut electric resistance welded pipes in the electric resistance welded pipe production line experiences an excessive load on hard tips thereof because of the limited cutting time, which results in reduced durability and chipping. [Solution] A flank 18 is provided with a first flank 20 located at the center thereof, and second and third flanks 22, 24 located inclined toward the respective sides of the first flank 20. Therefore, the lateral sides of the flank 18 have a constant clearance angle rearward from a cutting edge 34, which provides advantages of increased strength and resistance to chipping. Furthermore, a fourth flank 26 having a larger clearance angle is separately provided at the rear of the first flank 20 located at the center. Even if the first flank 20 wears, it is possible to reduce the wear on the fourth flank 26 and improve the durability.

Abstract: A circular saw blade to cut electric resistance welded pipes in the electric resistance welded pipe production line experiences an excessive load on hard tips thereof because of the limited cutting time, which results in reduced durability and chipping. [Solution] A flank 18 is provided with a first flank 20 located at the center thereof, and second and third flanks 22, 24 located inclined toward the respective sides of the first flank 20. Therefore, the lateral sides of the flank 18 have a constant clearance angle rearward from a cutting edge 34, which provides advantages of increased strength and resistance to chipping. Furthermore, a fourth flank 26 having a larger clearance angle is separately provided at the rear of the first flank 20 located at the center. Even if the first flank 20 wears, it is possible to reduce the wear on the fourth flank 26 and improve the durability.

Abstract: [OBJECT] To make tips less likely to be damaged. [MEANS OF REALIZING THE OBJECT] A tip (30) has a first rake face (40) that is contiguous with a cutting edge (32), and a second rake face (42) that is contiguous with the first rake face and faces a gullet (16) provided in front of the tip (30) in the rotational direction, wherein the second rake face (42) has a radially inward inner edge that is in contact with the outer peripheral edge of the base metal (12) that defines the gullet (16). The second rake face (42) is formed such that the second rake angle (02), which is formed between a first reference line (L1) drawn from the rotation center of the circular saw blade to the cutting edge (32) and a second reference line (L2) that passes through the radially inward inner edge along the second rake face (42), is a negative angle.