Circular saw blade with tips

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.

Claims

1. A circular saw blade having hard tips fixed at predetermined intervals on an outer periphery of a base metal, wherein: a rake angle of a rake face of a hard tip of the hard tips has a negative angle; a flank of the hard tip comprises a first flank located at a center of the flank, and second and third flanks positioned on opposite sides of the first flank and angled relative to the first flank; a fourth flank having a clearance angle larger than a clearance angle of the first flank is positioned rearward of the first flank and facing a direction opposite a rotational direction of the circular saw blade; and wherein the fourth flank has a trapezoidal shape intersecting the first flank via a ridge forming a top portion of the fourth flank, and intersecting with the second and third flanks via left and right ridges.

2. The circular saw blade according to claim 1, wherein the rake face comprises a cutting face of the hard tip.

3. The circular saw blade according to claim 1, wherein the rake face comprises a front face of the hard tip.

4. The circular saw blade according to claim 1, wherein the flank comprises a back side of the hard tip.

5. A circular saw blade comprising: a base; and a plurality of tips fixed at intervals on an outer periphery of the base; wherein: a rake angle of a rake face of a tip of the plurality of tips has a negative angle; the tip comprises a first flank, second and third flanks extending toward the base of the circular saw blade from opposite sides of the first flank, and a fourth flank having a clearance angle larger than a clearance angle of the first flank; and the fourth flank comprises a trapezoidal shape having a first and second base and a first and second leg, the first base being a common edge of the first and fourth flanks, the first leg being a common edge of the second and fourth flanks, and the second leg being a common edge of the third and fourth flanks.

6. The circular saw blade according to claim 5, wherein the rake face comprises a cutting face of the tip.

7. The circular saw blade according to claim 5, wherein the rake face comprises a front face of the tip.

8. The circular saw blade according to claim 5, wherein the first flank, the second flank, the third flank, and the fourth flank comprise a flank of the tip, and wherein the flank of the tip comprises a back side of the tip.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 A side view of a hard tip according to an embodiment of the invention.

(2) FIG. 2 A plan view of the hard tip shown in FIG. 1.

(3) FIG. 3 A front view of the hard tip shown in FIG. 1.

(4) FIG. 4 A rear view of the hard tip shown in FIG. 1.

(5) FIG. 5 An enlarged view of an upper side surface of the hard tip shown in FIG. 1.

(6) FIG. 6 A photograph showing the state of wear after hard tips of the embodiment were tested.

(7) FIG. 7 A photograph showing the state of wear after conventional hard tips were tested.

(8) FIG. 8 A side view of a circular saw blade with tips having hard tips fixed to the outer periphery of a base metal.

MODE FOR CARRYING OUT THE INVENTION

(9) Next, a circular saw blade according to the present invention will be described with reference to the drawings by way of a preferred embodiment. FIGS. 1 to 4 are views of a hard tip 14 of a circular saw blade made of, for example, cemented carbide, observed from various directions. In particular, FIG. 1 is a side view of the hard tip 14, with a circular saw blade 10 rotating in a direction indicated by an arrow A. A rake face 16 of the hard tip 14 is inclined upward at the front side of the tip body (the face directed in the rotational direction of the circular saw blade), with a rake angle of the rake face 16 being a negative angle.

(10) As may be seen from FIG. 2, in particular, the flank of the hard tip 14 is divided into four flanks. The flank refers to a surface that does not contact a work when cutting the work with a blade (hard tip), and, in the case of the hard tip of a circular saw blade, refers to a surface in a direction to retreat in the rotational direction of the circular saw blade.

(11) As may be seen from FIG. 2, a flank 18 of the hard tip 14 has a first flank 20 located at the center thereof and contacting the rake face 16 via a cutting edge (ridge) 34, and a second flank 22 and a third flank 24 which are inclined to the respective sides of the first flank 20 (left and right in FIG. 2). A fourth flank 26 being adjacent to the first flank 20 via the ridge 28 and having a clearance angle larger than a clearance angle of the first flank 20 is formed rearward of the first flank 20. The relation (<) of the clearance angle being larger than the clearance angle is shown in an enlarged view in FIG. 5. If the clearance angle of the fourth flank 26 is set too large (for example, 20 or greater), the trapezoid (to be described later) becomes a hexagon, so that at the time of polishing the fourth flank 26, the base metal rearward of the rotating hard tip 14 may be scraped, or polishing may take extra time.

(12) As shown in FIG. 2, the fourth flank 26 has a trapezoidal shape with the first flank 20 serving as the top side and the ridge on the back side of the hard tip 14 serving as the base. That is, the fourth flank 26 has, as a top portion, a ridge 28 which is a boundary intersecting with the first flank 20, intersects with the second flank 22 via a right ridge 30 in FIG. 2, and intersects with the third flank 24 via a left ridge 32, so that the fourth flank 26 has a trapezoidal shape or a shape like that of Mt. Fuji as a whole. In other words, the area of the fourth flank 26 is set to be sufficiently larger than the area of the first flank 20.

(13) Further, as shown in FIGS. 2 to 4, the hard tip 14 is provided with a dividing groove 36 extending from the cutting edge (ridge) 34 where the rake face 16 and the flank 18 intersect with each other to the flank 18. According to the circular saw blade of the embodiment of the invention, the clearance angle is constant from the cutting edge of the flank to the rear side at a portion close to the side face of the flank, so that the hard tip 14 is strong so as not to be easily chipped. Also, only the central portion of the cutting edge on the flank has two flank stages, so that even if the first stage wears early, the large clearance angle of the second stage may decrease the abrasion width, thus improving the durability.

TEST EXAMPLE

(14) Cutting was carried out under the same conditions using a circular saw blade using hard tips according to the embodiment and a circular saw blade using the conventional hard tips to compare the wearing states of the tips.

(15) [Cutting Conditions]

(16) A hollow pipe made of X60 (for oil well pipe) was used as a work piece. The pipe was 52 mm in diameter, and 6.0 mm in thickness.

(17) The circular saw blade in use had an outer diameter of 430 mm, a tooth width of 6.0 mm, and 54 teeth.

(18) Conditions: the peripheral velocity V=300 m/min, Sz1=0.1 mm/z, and Sz2=0.18 mm/z

(19) The following are the wearing states of the hard tips of the tested circular saw blades.

(20) TABLE-US-00001 TABLE 1 Achieved cutting area Specification (m.sup.2) of work piece Wearing width (mm) Tips of embodiment 4.7 0.8 0.4 Conventional tips 4.0 0.7 1.3
[Wearing States]

(21) Significant differences in wearing state between the hard tips of the example and the conventional hard tips were observed. Despite the achievement of 4.7 m.sup.2, the circular saw blade of the example had a smaller wearing width than the conventional circular saw blade with the achievement of 4.0 m.sup.2. The peripheral wear was suppressed at the boundary line of the outer diameters of the two stages as intended.

(22) FIGS. 6 and 7 show the wearing states of the hard tips. The hard tips according to the example shown in FIG. 6 well show less wearing.

DESCRIPTION OF REFERENCE NUMERALS

(23) 10 Circular saw blade with tips 12 Base metal 14 Hard tip 16 Rake face 18 Flank 20 First flank 22 Second flank 24 Third flank 26 Fourth flank 28 Ridge 30 Right ridge 32 Left ridge 34 Cutting edge (ridge) 36 Dividing groove Clearance angle Clearance angle (<) Rake angle