Circular saw blade

Abstract

There is a need for a circular saw blade that can suppress the tightening of the saw blade body by the metal workpiece while also suppressing cutting resistance. [Solution] The circular saw blade has a disc-shaped base plate 2, a thin blade tip 10, and a thick blade tip 20. The thin blade tip 10 and the thick blade tip 20 are alternately joined to the outer circumference of the base plate 2. Both the thin blade tip 10 and the thick blade tip 20 have first rake faces 11, 21 and a pair of second rake faces 12, 22. The first rake faces 11, 21 are located in the center of the thickness direction of the thin blade tip 10 and the thick blade tip 20 and have a negative rake angle. The pair of second rake faces 12, 22 are located on both sides of the thickness direction of the thin blade tip 10 and the thick blade tip 20 and have a negative rake angle and a negative transverse rake angle, and are inclined radially inward from both ends of the thickness direction of the first rake faces 11, 21 to the base plate 2. The thin blade tip 10 has a thinner blade thickness than the thick blade tip 20 and protrudes radially outward from the thick blade tip 20.

Description

Technical Field

[0001] The present invention relates to a circular saw blade used for cutting a work material such as a metal material like steel.

Background Art

[0002] As disclosed in Patent Documents 1 to 3, circular saw blades used for cutting metal and non-ferrous metal materials have been conventionally provided. In the conventionally provided circular saw blades, for example, work materials such as plate materials, pipe materials, and small-diameter bar materials made of non-ferrous metals such as aluminum and copper, and stainless steel can be cut. However, for example, when cutting a large-diameter bar material with a diameter exceeding 200 mm made of a duplex stainless steel material using a circular saw blade, the circular saw blade is clamped in the cutting groove of the work material due to the residual stress of the work material during cutting, and the rotation of the circular saw blade may stop halfway and cutting may not be possible. Also, due to an increase in cutting resistance caused by clamping of the work material, vibration may occur during cutting, and the cutting edge (tip) of the circular saw blade may be damaged.

[0003] In order to mitigate the influence on the circular saw blade due to the clamping phenomenon of the work material, it is conceivable to increase the rake angle by increasing the blade thickness of the tip. Thereby, contact between the saw blade body (base alloy) and the work material that tightens toward the inside of the cutting groove can be avoided. Therefore, clamping of the base alloy by the work material can be suppressed. However, when the blade thickness of the tip is increased, the cutting resistance increases, so in the case where the output of the cutting machine is insufficient or in an old cutting machine, etc., vibration may be generated during cutting, causing damage to the cutting edge, etc. Patent Document 1 discloses providing a tip with a reverse rake angle in order to eliminate the clamping phenomenon of the work material. In this case as well, since the cutting resistance increases, there is a risk of generating vibration in the circular saw blade. Also, it is difficult to cut hard materials such as duplex stainless steel in the first place.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Therefore, there is a need for a circular saw blade that can suppress cutting resistance while preventing the saw blade body from being tightened by the metal workpiece. [Means for solving the problem]

[0006] According to one feature of this disclosure, the circular saw blade has a disc-shaped base plate and thin-blade tips and thick-blade tips. The thin-blade tips and thick-blade tips are alternately joined to the outer circumference of the base plate. Both the thin-blade tips and thick-blade tips have a first rake face and a pair of second rake faces. The first rake face is located in the center of the thickness direction of the thin-blade tip and thick-blade tip and has a negative rake angle. The pair of second rake faces are located on both sides of the thickness direction of the thin-blade tip and thick-blade tip and have a negative rake angle and a negative transverse rake angle and are inclined radially inward from both ends of the thickness direction of the first rake face to the base plate. The thin-blade tip has a thinner blade thickness than the thick-blade tip and protrudes radially outward more than the thick-blade tip.

[0007] Thin-blade and thick-blade tips have a first rake face and a pair of second rake faces, which are suitable for cutting metal materials, especially stainless steel. Because the thick-blade tips have a large kerf, the workpiece that is compressed within the cutting groove does not come into contact with the base metal. Therefore, the compression of the base metal by the workpiece can be suppressed. Furthermore, the thin-blade and thick-blade tips are arranged alternately in the circumferential direction, and the thin-blade tips protrude radially outward more than the thick-blade tips. As a result, the thin-blade and thick-blade tips cut by dividing the cutting groove in the thickness direction. This suppresses the cutting resistance of each tip and reduces the overall cutting resistance of the circular saw blade.

[0008] According to other features of this disclosure, both the thin-bladed tip and the thick-bladed tip have a first flank face, a second flank face, and a breaker face. The first flank face is connected to a first cutting edge at the radially outer end of the first rake face. The second flank face is connected to a second cutting edge at the radially outer end of the second rake face. The breaker face is connected to a first inner ridge at the radially inner end of the first rake face and a second inner ridge at the radially inner end of the second rake face. The first cutting edge and the first inner ridge are substantially parallel, and the second cutting edge and the second inner ridge are substantially parallel. The first rake face and the second rake face intersect at both ends of the first rake face.

[0009] Therefore, the first and second rake faces have approximately constant radial widths. The first and second rake faces can be provided at a suitable size, neither too wide nor too narrow. This suppresses chip welding that may occur during cutting when the first and second rake faces are wide, for example. It also suppresses chipping of each rake face that may occur during cutting when the first and second rake faces are narrow, for example. Furthermore, by providing breaker surfaces radially inward of the first and second rake faces, chips can be quickly discharged. Thus, breakage and increased cutting resistance in thick and thin cutting tips can be suppressed.

[0010] According to other features of this disclosure, the radial height difference between the thin-blade tip and the thick-blade tip is 0.10 mm to 0.25 mm. Therefore, if the height difference is small, the chips are not properly divided in the thickness direction and damage the end face of the cut workpiece, so the lower limit of the height difference is set to 0.10 mm. If the height difference is large, the area cut by the cutting edges at both ends in the thickness direction of the second rake face of the thin-blade tip and the area cut by the cutting edges at both ends radially outward of the second rake face of the thick-blade tip become close in the cutting direction. Therefore, there is a risk of the thick-blade tip chipping when it cuts areas that have been work-hardened by the cutting of the thin-blade tip. For this reason, the upper limit of the height difference is set to 0.25 mm to prevent cutting of work-hardened areas. Thus, by setting the height difference to a predetermined height, the workpiece can be cut well and damage to each tip can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1]This is a side view of the circular saw blade related to this disclosure. [Figure 2] This is a magnified perspective view of the outer circumference of a circular saw blade. [Figure 3] This is an enlarged side view of the outer circumference of a circular saw blade. [Figure 4] This is a front view of the thick blade tip and the thin blade tip as seen from the front in the direction of rotation. [Figure 5] This is a schematic diagram showing the cutting edges of a thick blade tip and a thin blade tip superimposed from the front in the direction of rotation. [Figure 6] This is a top view of the thick and thin blade tips, seen from the radially outward direction. [Figure 7] This is a perspective view of a thin blade tip. [Figure 8] This is a perspective view of a thick blade tip. [Figure 9] This is a schematic diagram of the chips produced when the height difference between the thick and thin cutting tips is 0.05 mm. [Figure 10] This is a schematic diagram of the chips produced when the height difference between the two chips is 0.10 mm. [Figure 11] This is a schematic diagram of the chips produced when the height difference between the two chips is 0.15 mm. [Figure 12] This is a schematic diagram of the chips produced when the height difference between the two chips is 0.20 mm. [Figure 13] This is a schematic diagram of the chips produced when the height difference between the two chips is 0.30 mm. [Figure 14] This is a schematic diagram of the chips produced when the height difference between the two chips is 0.35 mm. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present disclosure will be described based on FIGS. 1 to 14. The same reference numerals in the description do not repeat the description but mean the same elements having the same functions. In this embodiment, a circular saw blade 1 for metal processing is exemplified. As shown in FIG. 1, the circular saw blade 1 has a disk-shaped base metal 2, a plurality of thin blade tips 10 and a plurality of thick blade tips 20 attached to the outer periphery of the base metal 2. The thin blade tips 10 and the thick blade tips 20 are arranged alternately in the circumferential direction, and in this embodiment, they are arranged alternately one by one. In other words, a chip group 6 in which the thin blade tips 10 and the thick blade tips 20 are continuous is arranged in a plurality of sets in the circumferential direction of the base metal 2. By rotating the base metal 2, the thin blade tips 10 and the thick blade tips 20 sequentially cut the workpiece to form a cutting groove, and finally cut the workpiece. The workpiece is, for example, a steel material such as stainless steel, heat-resistant steel, chromium steel, nickel steel, etc., and particularly targets a steel material such as duplex stainless steel that is hard and has a large residual stress. The workpiece is, for example, a solid material in the shape of a rod or a thick plate, etc., and is, for example, a solid material in the shape of a rod with a large diameter exceeding 200 mm. The workpiece is, for example, cut at room temperature.

[0013] As shown in FIG. 1, a mounting hole 2b penetrating in the thickness direction is provided at the center of the base metal 2. The mounting hole 2b is circular with the base metal axis 2a as the center. The rotating shaft of the circular sawing machine is inserted into the mounting hole 2b. The circular saw blade 1 rotates in the circumferential direction around the base metal axis 2a. The plurality of thin blade tips 10 and the plurality of thick blade tips 20 arranged on the outer periphery of the base metal 2 reach the workpiece in sequence as they rotate and cut the workpiece. On the outer periphery rather than the mounting hole 2b, a plurality of substantially circular holes 2d penetrating the base metal 2 in the thickness direction are arranged at substantially equal intervals in the circumferential direction. The holes 2d are connected to a support portion that supports the rotating shaft around the rotating shaft. The outer diameter of the circular saw blade 1 is larger than three times the maximum cutting length such as the diameter or thickness of the workpiece, and is, for example, 500 mm to 1500 mm. The base metal 2 is, for example, made of steel. As shown in FIG. 4, the thickness 2c of the base metal 2 is thinner than the blade thickness 10a of the thin blade tip 10, and is, for example, 4.8 mm.

[0014] As shown in FIGS. 1 and 2, the base metal 2 has a plurality of protrusions 3 that project radially outward from the outer peripheral portion. The plurality of protrusions 3 are arranged at predetermined intervals in the circumferential direction, for example, at equal intervals in the circumferential direction. A tooth chamber 4 is formed between adjacent protrusions 3 in the circumferential direction. A chip seat 5 that opens radially outward on the front side in the rotational direction is formed in the protrusion 3. A thin blade chip 10 or a thick blade chip 20 is mounted on each chip seat 5. The circular saw blade 1 has, for example, 20 to 40 thin blade chips 10 and 20 to 40 thick blade chips 20 respectively, for example, 26 of each.

[0015] The thin blade chip 10 and the thick blade chip 20 shown in FIG. 2 are hard chips formed of, for example, cemented carbide or cermet. Cemented carbide is obtained by mixing, for example, tungsten carbide and cobalt as a binder and sintering. Cermet is obtained by mixing TiN, TiC, TiCN, etc. and nickel as a binder and sintering. A coating or the like for improving wear resistance may be applied to the surfaces of the thin blade chip 10 and the thick blade chip 20.

[0016] As shown in FIG. 2, the thin blade chip 10 and the thick blade chip 20 are formed in a substantially rectangular box shape. As shown in FIGS. 4 and 5, the thin blade chip 10 is provided with a blade thickness 10a of, for example, 6.0 mm to 7.0 mm, for example, 6.5 mm. The thick blade chip 20 is provided with a blade thickness 20a that is larger than the blade thickness 10a, for example, 7.5 mm to 8.5 mm, for example, 8.0 mm. In the following description, the radially outer side of the base metal 2 is also referred to as upward, and the radially inner side is also referred to as downward. The front-rear direction of the thin blade chip 10 and the thick blade chip 20 is defined such that the front in the rotational direction of the circular saw blade 1 is the front and the rear in the rotational direction is the rear. The left and right in the thickness direction of the thin blade chip 10 and the thick blade chip 20 are defined as the left and right in the thickness direction as viewed from the front in the rotational direction of the circular saw blade 1.

[0017] As shown in Figure 7, the thin blade tip 10 has a first rake face 11 at the front upper center in the left-right direction. The first rake face 11 extends planar in the left-right direction and has a first cutting edge 11a at its upper end and a first inner ridge 11b at its lower end. The first cutting edge 11a and the first inner ridge 11b extend approximately parallel to each other in the left-right direction. The thin blade tip 10 has a pair of planar second rake faces 12 that intersect and connect at both the left and right ends of the first rake face 11. The left second rake face 12a is inclined downward toward the left, away from the first rake face 11. The right second rake face 12b is inclined downward toward the right, away from the first rake face 11. The second rake face 12 has a second cutting edge 12c at its upper end and a second inner ridge 12d at its lower end. The second cutting edge 12c and the second inner ridge 12d extend substantially parallel to each other. The first cutting edge 11a and the pair of second cutting edges 12c cut the workpiece.

[0018] If the second cutting edge 12c and the second inner ridge 12d are arranged to move away from each other outward to the left and right, in other words, if the second rake face 12 is arranged to widen outward to the left and right, chip welding is likely to occur near the end of the second rake face 12 that is close to the cutting groove. If the second cutting edge 12c and the second inner ridge 12d are arranged to move closer to each other outward to the left and right, in other words, if the second rake face 12 is arranged to narrow outward to the left and right, the strength of the end of the second rake face 12 that is close to the cutting groove will decrease. As a result, there is a risk of chipping of the second rake face 12. Therefore, in this embodiment, the occurrence of the above phenomenon is suppressed by providing the second cutting edge 12c and the second inner ridge 12d to be approximately parallel to each other.

[0019] As shown in Figure 3, the first rake face 11 and the second rake face 12 are inclined backward toward upward (radially outward) with respect to the radial line L1 passing through the base metal axis 2a (see Figure 1). The rake angle 11c of the first rake face 11 is a negative value, for example -35° to -10°, or for example -25°. The rake angle of the second rake face 12 is also a negative value. As shown in Figure 4, the first cutting edge 11a and the first inner ridge line 11b are provided with a vertical gap of, for example 0.20 mm to 1.50 mm, or for example 0.50 mm, when viewed from the front. The radial width 11e is greater than the height difference 10c between the thin blade tip 10 and the thick blade tip 20, which will be described later. The second cutting edge 12c and the second inner ridge line 12d are provided with a vertical gap approximately the same as the radial width 11e.

[0020] As shown in Figure 4, the second rake face 12 is inclined downward with respect to the first rake face 11 at a chamfer angle 12e when viewed from the front. The chamfer angle 12e is, for example, 10° to 35°, or 25°. The second rake face 12 is provided with a chamfer width 10b in the left-right direction, for example, 0.5 mm to 3.0 mm, or 1.0 mm. As shown in Figure 6, the second rake face 12 is inclined backward with respect to the first rake face 11 at a lateral rake angle 12f when viewed from above. The lateral rake angle 12f is a negative value, for example, -25° to -5°.

[0021] As shown in Figure 7, the thin blade tip 10 has a first relief surface 13 that is connected to the first cutting edge 11a of the first rake face 11 and extends rearward. The thin blade tip 10 has a second relief surface 14 that is connected to the second cutting edge 12c of the second rake face 12 and extends rearward. The left second relief surface 14a is provided behind the left second rake face 12a. The right second relief surface 14b is provided behind the right second rake face 12b. The second relief surfaces 14 are aligned with the inclination direction of the second rake face 12 and inclined downward toward both the left and right ends. As shown in Figure 3, the first relief surface 13 is inclined downward toward the rear (radially inward) at a relief angle 11d with respect to the circumferential line L2 which is perpendicular to the radial line L1. The relief angle 11d of the first relief surface 13 is, for example, 5° to 10°, and for example, 6°.

[0022] As shown in Figure 7, the thin-blade tip 10 has a breaker surface 15 connected to the first inner ridge 11b of the first rake face 11 and the second inner ridge 12d of the second rake face 12. The breaker surface 15 is arc-shaped, extending vertically when viewed from the left and right directions. The breaker surface 15 is concave toward the rear. As shown in Figure 3, the breaker surface 15 has a positive rake angle at its upper end where it connects to the first inner ridge 11b and the second inner ridge 12d. The chips cut by the first cutting edge 11a and the second cutting edge 12c are sent towards the first rake face 11 and the second rake face 12 and bent into a coil spring shape by the breaker surface 15. The chips bent by the breaker surface 15 are discharged from the groove or tooth chamber 4 formed in the workpiece using elastic force. In particular, when the workpiece material is stainless steel, chips tend to adhere to the thin blade tip 10, so the chips can be quickly separated from the thin blade tip 10.

[0023] As shown in Figure 7, the thin-blade tip 10 has a left side surface 16 and a right side surface 17 that extend planarly in the vertical and front-back directions on both sides in the left-right direction. The left side surface 16 extends downward from the left end of the left second rake face 12. The right side surface 17 extends downward from the right end of the right second rake face 12. The left side surface 16 and the right side surface 17 have a set angle 16a, 17a that is 0° to 2° with respect to the vertical direction, for example, 1°30′ towards the inside. This slight inclination reduces the contact area with the workpiece, thereby reducing cutting resistance. Moreover, because the left side surface 16 and the right side surface 17 do not protrude too much from the cut surface of the workpiece, the finish of the cut surface can be made smooth.

[0024] As shown in Figure 6, the left side surface 16 and the right side surface 17 have side relief angles 16b and 17b that are inward from front to rear in the front-to-back direction. The side relief angles 16b and 17b are approximately the same size, for example, 30′ to 3° and 2°. Even a slight inclination of the side relief angles 16b and 17b reduces the contact area with the workpiece. This reduces cutting resistance and allows for a smoother finish of the cut surface. The left side surface 16 and the right side surface 17 have kerfs 16c and 17c of approximately the same size relative to the left and right sides of the base metal 2.

[0025] As shown in Figure 8, the thick blade tip 20 has substantially the same configuration as the thin blade tip 10 (see Figure 7), except that the blade thickness is different. That is, the thick blade tip 20 has a planar first rake face 21 in the center in the left-right direction on the front upper side. The first rake face 21 has a first cutting edge 21a at the upper end and a first inner ridge 21b at the lower end, both extending substantially parallel to each other in the left-right direction. The thick blade tip 20 has a pair of planar second rake faces 22 that intersect and connect at both the left and right ends of the first rake face 21. The second rake face 22a on the left and the second rake face 22b on the right each incline downward as they move away from the first rake face 21. The second rake faces 22 have a second cutting edge 22c at the upper end and a second inner ridge 22d at the lower end, both extending substantially parallel to each other. By arranging the second cutting edge 22c and the second inner ridge line 22d substantially parallel to each other, chip welding and chipping on the second rake face 22 can be suppressed. The first cutting edge 21a and the pair of second cutting edges 22c cut the workpiece.

[0026] As shown in Figure 3, the first rake face 21 and the second rake face 22 are inclined backward toward upward (radially outward) with respect to the radial line L1. The rake angle 21c of the first rake face 21 is a negative value of approximately the same magnitude as the rake angle 11c. The rake angle of the second rake face 22 is also a negative value of approximately the same magnitude as the rake angle of the second rake face 12. As shown in Figure 4, the first cutting edge 21a and the first inner ridge 21b are provided with a vertical gap of approximately the same radial width 21e as the radial width 11e when viewed from the front. The second cutting edge 22c and the second inner ridge 22d are provided with a vertical gap of approximately the same radial width 21e.

[0027] As shown in Figure 4, the second rake face 22 is inclined downward with respect to the first rake face 21 at a chamfer angle 22e that is approximately the same as the chamfer angle 12e when viewed from the front. The second rake face 22 is provided with a chamfer width 20b that is approximately the same as the chamfer width 10b. As shown in Figure 6, the second rake face 22 is inclined backward with respect to the first rake face 21 at a lateral rake angle 22f that is approximately the same as the lateral rake angle 12f when viewed from above.

[0028] As shown in Figure 8, the thick blade tip 20 has a first relief surface 23 that is connected to the first cutting edge 21a of the first rake face 21 and extends rearward. The thick blade tip 20 has a second relief surface 24 that is connected to the second cutting edge 22c of the second rake face 22 and extends rearward. Second relief surfaces 24a and 24b are provided behind the left and right second rake faces 22a and 22b, respectively. The second relief surface 24 is aligned with the inclination direction of the second rake face 22 and inclined downward toward both the left and right ends. As shown in Figure 3, the first relief surface 23 is inclined downward toward the rear (radially inward) with respect to the circumferential line L2 at a relief angle 21d that is approximately the same size as the relief angle 11d.

[0029] As shown in Figure 8, the thick blade tip 20 has a breaker surface 25 connected to the first inner ridge 21b of the first rake face 21 and the second inner ridge 22d of the second rake face 22. The breaker surface 25 is arc-shaped and extends vertically when viewed from the left-right direction. The breaker surface 25 is concave toward the rear. The breaker surface 25 has a positive rake angle at its upper end where it connects to the first inner ridge 21b and the second inner ridge 22d (see Figure 3). The thick blade tip 20 has a left side surface 26 and a right side surface 27 that extend planarly in the vertical and front-back directions on both sides in the left-right direction. The left side surface 26 extends downward from the left end of the second rake face 22 on the left. The right side surface 27 extends downward from the right end of the second rake face 22 on the right. The left side 26 and the right side 27 have inwardly positioned clam angles 26a and 27a, which are approximately the same size as the clam angles 16a and 17a. As shown in Figure 6, the left side 26 and the right side 27 are inwardly positioned from front to rear in the anterior-posterior direction and have side relief angles 26b and 27b, which are approximately the same size as the side relief angles 16b and 17b. The left side 26 and the right side 27 have clam angles 26c and 27c that are approximately the same size as the left and right sides of the base metal 2 and are larger than the clam angles 16c and 17c.

[0030] As shown in Figure 6, the thin blade tip 10 and the thick blade tip 20 are mounted on the base plate 2 so that their centers are aligned in the left-right direction. As shown in Figures 4 and 5, the thin blade tip 10 protrudes upward from the thick blade tip. The first rake face 11 of the thin blade tip 10 is positioned above the first rake face 21 of the thick blade tip 20 by a height difference of 10c. The height difference of 10c is, for example, 0.10mm to 0.25mm, and more preferably 0.15mm to 0.20mm. The left second cutting edge 12c of the thin blade tip 10 is positioned generally to the right of the left second cutting edge 22c of the thick blade tip 20. The right second cutting edge 12c of the thin blade tip 10 is positioned generally to the left of the right second cutting edge 22c of the thick blade tip 20. In other words, the second cutting edge 12c of the thin blade tip 10 is positioned generally inward in the left-right direction relative to the second cutting edge 22c of the thick blade tip 20. Similarly, the left side 16 and right side 17 of the thin blade tip 10 are generally positioned inward in the left-right direction relative to the left side 26 and right side 27 of the thick blade tip 20. In other words, the thin blade tip 10 is generally thinner in the left-right direction relative to the thick blade tip 20.

[0031] Cutting tests were conducted using the circular saw blade 1 of this embodiment described above, and it was possible to cut metal materials that could not be cut with conventional circular saw blades for cutting metal. For comparison, a circular saw blade with thin-blade tips 10 on all blades and a circular saw blade with thick-blade tips 20 on all blades were used as conventional products. The circular saw blade with thin-blade tips 10 on all blades stopped rotating when it was tightened against the workpiece while cutting a 205 mm diameter double-layer stainless steel round bar. In addition, with the circular saw blade with thick-blade tips 20 on all blades, vibration occurred during cutting and the tips broke. Therefore, it was not possible to cut the workpiece. On the other hand, the circular saw blade 1 of this embodiment was able to cut a round bar of the same double-layer stainless steel material with a diameter of 285 mm, which is larger than 205 mm.

[0032] The chips generated when split cutting of the workpiece with thin-blade tips 10 and thick-blade tips 20 will be explained with reference to Figures 9 to 14. The thin-blade tips 10 and thick-blade tips 20 are arranged alternately one by one in the circumferential direction (see Figure 1). The depth of cut Sz from when one thin-blade tip 10 cuts until the next thin-blade tip 10 cuts (or from when one thick-blade tip 20 cuts until the next thick-blade tip 20 cuts) was kept constant at 0.08 mm under the same conditions. If the depth of cut Sz is less than, for example, 0.05 mm, the cutting edge will cut the work-hardened area near the cut surface. Therefore, the depth of cut Sz was set to a value of 0.05 mm or more. Figures 9 to 14 show diagrams with mutually different height differences 10c (see Figure 5). The height difference of 10c is 0.05mm in Figure 9, 0.10mm in Figure 10, 0.15mm in Figure 11, 0.20mm in Figure 12, 0.30mm in Figure 13, and 0.35mm in Figure 14.

[0033] As shown in Figures 9-14, chip 31 is formed in the center of the cutting groove in the left-right direction, and chip 32 is formed on both the left and right sides of the cutting groove. The chip 31 is surrounded by cutting edges 31a and 31c cut by the first cutting edge 11a of the thin blade tip 10, cutting edges 31b and 31d cut by the second cutting edge 12c of the thin blade tip 10, and cutting edge 31e cut by the first cutting edge 21a of the thick blade tip 20 (see Figure 5). Cutting edges 31a and 31b are cut by the thin blade tip 10 immediately preceding the thin blade tip 10 that cuts cutting edges 31c and 31d. The chip 32 is surrounded by cutting lines 32a and 32c cut by the first cutting edge 21a of the thick blade tip 20, cutting lines 32b and 32d cut by the second cutting edge 22c of the thick blade tip 20, and cutting line 32e cut by the second cutting edge 12c of the thin blade tip 10 (see Figure 5). Cutting lines 32a and 32b are cut by the thick blade tip 20 immediately preceding the thick blade tip 20 that cuts cutting lines 32c and 32d. The thickness of the chips 31 and 32 in the cutting direction corresponds to the cutting depth Sz.

[0034] As shown in Figure 9, when the height difference 10c (see Figure 4) is as low as 0.05 mm, the chips are not separated, and the chips generated by the cutting of the thick blade tip 20 remain connected by the blade thickness of the thick blade tip 20, severely damaging the end face of the cut workpiece. For this reason, split cutting with the thin blade tip 10 and the thick blade tip 20 is not suitable. As shown in Figures 10 to 12, when each cutting edge line is of a predetermined length or longer, the chips are reliably separated between the cutting edge of the thin blade tip 10 and the cutting edge of the thick blade tip 20. For this reason, split cutting can be suitably performed with the thin blade tip 10 and the thick blade tip 20.

[0035] As shown in Figure 14, when the height difference 10c (see Figure 4) is as high as 0.35 mm, the area cut by the cutting edges at both ends in the thickness direction of the second rake face 12 of the thin blade tip 10 and the area cut by the cutting edges at both ends radially outward of the second rake face 22 of the thick blade tip 20 become close in the cutting direction. In other words, the chip 31 includes the cutting edge line 31f cut by the second cutting edge 22c of the thick blade tip 20, and the chip 32 includes the cutting edge line 32e cut by the second cutting edge 12c of the thin blade tip 10. As a result, the chips 31 and 32 include areas with a thickness of less than 0.05 mm in the cutting direction where work hardening may occur. Therefore, there is a risk of chipping as the thin blade tip 10 and the thick blade tip 20 cut through the work-hardened areas. In addition, the areas near the cutting edges on both the left and right sides 16 and 17 of the thin blade tip 10 are subjected to the tightening of the workpiece, which may cause chipping. Therefore, a height difference of 10cm was set to a value lower than 0.35mm.

[0036] The maximum value hmax[mm] of the height difference 10c was calculated using the following formula (1), with the blade thickness 10a of the thin blade tip 10 being T1[mm], the blade thickness 20a of the thick blade tip 20 being T2[mm], the chamfer angles 12e and 22e being θ[°], the chamfer widths 10b and 20b being W[mm], and the depth of cut being Sz[mm]. The maximum value hmax[mm] of the height difference 10c was calculated using the following formula (2). The minimum value hmin[mm] of the height difference 10c was calculated using the following formula (2). With T1=8.0mm, T2=6.5mm, θ=25°, W=1.0mm, and Sz=0.08mm, hmax=0.31mm and hmin=0.04mm were calculated. Based on the calculation results, it was concluded that a height difference of 10c in the range between hmax and hmin, for example, 0.10mm to 0.25mm, is preferable. hmax=tanθ×(T2 / 2-W-(T1-2×W) / 2)-Sz / 2……(1) hmin = Sz / 2 ... (2)

[0037] As described above, the circular saw blade 1 has a disc-shaped base plate 2, a thin blade tip 10, and a thick blade tip 20, as shown in Figures 1-4 and 6. The thin blade tip 10 and the thick blade tip 20 are alternately joined to the outer circumference of the base plate 2. Both the thin blade tip 10 and the thick blade tip 20 have first rake faces 11, 21 and a pair of second rake faces 12, 22. The first rake faces 11, 21 are located in the center of the thickness direction of the thin blade tip 10 and the thick blade tip 20 and have negative rake angles 11c, 21c. The pair of second rake faces 12, 22 are located on both sides of the thickness direction of the thin blade tip 10 and the thick blade tip 20 and have negative rake angles and negative transverse rake angles 12f, 22f, and are inclined radially inward from both ends of the first rake faces 11, 21 in the thickness direction of the base plate 2. The thin blade tip 10 has a thinner blade thickness than the thick blade tip 20 and protrudes radially outward more than the thick blade tip 20.

[0038] The thin-blade tip 10 and the thick-blade tip 20 have first rake faces 11, 21 and a pair of second rake faces 12, 22, which are suitable for cutting metal materials, especially stainless steel. Because the thick-blade tip 20 has a large kerf, the workpiece that is compressed in the cutting groove does not come into contact with the base metal 2. Therefore, it is possible to suppress the compression of the base metal 2 by the workpiece. Furthermore, the thin-blade tip 10 and the thick-blade tip 20 are arranged alternately in the circumferential direction, and the thin-blade tip 10 protrudes radially outward from the thick-blade tip 20. As a result, the thin-blade tip 10 and the thick-blade tip 20 cut by dividing the cutting groove in the thickness direction. This suppresses the cutting resistance of each tip and suppresses the overall cutting resistance of the circular saw blade 1.

[0039] As shown in Figures 2, 7, and 8, both the thin-blade tip 10 and the thick-blade tip 20 have first relief faces 13, 23 and second relief faces 14, 24 and breaker faces 15, 25. The first relief faces 13, 23 are connected to the first cutting edges 11a, 21a at the radially outer ends of the first rake faces 11, 21. The second relief faces 14, 24 are connected to the second cutting edges 12c, 22c at the radially outer ends of the second rake faces 12, 22. The breaker faces 15, 25 are connected to the first inner ridges 11b, 21b at the radially inner ends of the first rake faces 11, 21 and the second inner ridges 12d, 22d at the radially inner ends of the second rake faces 12, 22. The first cutting edges 11a, 21a and the first inner ridges 11b, 21b are approximately parallel, and the second cutting edges 12c, 22c and the second inner ridges 12d, 22d are approximately parallel. The first rake faces 11, 21 and the second rake faces 12, 22 intersect at both ends of the first rake faces 11, 21.

[0040] Therefore, the first rake faces 11,21 and the second rake faces 12,22 have approximately constant radial widths. The first rake faces 11,21 and the second rake faces 12,22 can be provided at a suitable size that is neither too wide nor too narrow. This suppresses chip welding that may occur during cutting when the first rake faces 11,21 and the second rake faces 12,22 are wide. It also suppresses chipping of each rake face that may occur during cutting when the first rake faces 11,21 and the second rake faces 12,22 are narrow. Furthermore, by providing breaker faces 15,25 radially inward of the first rake faces 11,21 and the second rake faces 12,22, chips can be quickly discharged. Thus, damage to the thin-blade tip 10 and the thick-blade tip 20 and an increase in cutting resistance can be suppressed.

[0041] As shown in Figures 4 and 5, the radial height difference 10c between the thin blade tip 10 and the thick blade tip 20 is 0.10 mm to 0.25 mm. Therefore, if the height difference 10c is small, the chips will not be properly divided in the thickness direction and the end face of the cut workpiece will be damaged, so the lower limit of the height difference is set to 0.10 mm. If the height difference 10c is large, the area cut by the cutting edges at both ends in the thickness direction of the second rake face 12 of the thin blade tip 10 (second cutting edge 12c) and the area cut by the cutting edges at both ends radially outward of the second rake face 22 of the thick blade tip 20 (second cutting edge 22c) become close in the cutting direction. Therefore, there is a risk that the thick blade tip 20 may cut through work-hardened areas caused by cutting by the thin blade tip 10, causing chipping of the blade. For this reason, the upper limit of the height difference 10c is set to 0.25 mm to prevent cutting through work-hardened areas. Thus, by setting a height difference of 10c at a predetermined height, the workpiece can be cut well and damage to each chip can be suppressed.

[0042] Various modifications can be made to the circular saw blade 1 of this embodiment described above. For example, the outer diameter of the circular saw blade 1, the thickness 2c of the base metal 2, the total number of teeth, the blade thickness 10a of the thin blade tip 10, the blade thickness 20a of the thick blade tip 20, the chamfer widths 10b, 20b, the chamfer angles 12e, 22e, etc., are not limited to those exemplified and may be changed as appropriate. The present disclosure may be applied not only to workpiece materials such as stainless steel, but also to workpiece materials with large residual stresses, such as non-stainless steel metal plates that are sufficiently thick.

[0043] An example of a circular saw blade 1 is shown, in which thin blade tips 10 and thick blade tips 20 are arranged alternately one at a time in the circumferential direction of the base metal 2. The number of alternating thin blade tips 10 and thick blade tips 20 is not limited to that shown in the example. For example, it may be a structure in which two thin blade tips 10 and two thick blade tips 20 are arranged alternately, or a structure in which three or more thin blade tips 10 and three or more thick blade tips 20 are arranged alternately. For example, a structure in which two thin blade tips 10 and one thick blade tip 20 are arranged alternately, or a structure in which one thin blade tip 10 and two thick blade tips 20 are arranged alternately, etc., the number of thin blade tips 10 and thick blade tips 20 do not have to be equal.

[0044] An example of a circular saw blade 1 having one type of thin blade tip 10 and one type of thick blade tip 20 is shown. Alternatively, for example, it may have one type of thin blade tip and multiple types of thick blade tips, or multiple types of thin blade tips and one type of thick blade tip, or multiple types of thin blade tips and multiple types of thick blade tips. An example of a circular saw blade 1 in which the protrusions 3 are arranged at equal intervals in the circumferential direction of the base metal 2 is shown. Alternatively, the protrusions 3 may be provided at unequal intervals, for example, the tooth chamber 4 in the rotational direction forward of the thin blade tip 10 and the tooth chamber 4 in the rotational direction forward of the thick blade tip 20 may be of different sizes. [Explanation of symbols]

[0045] 1…Circular saw blade 2...base plate, 2a...base plate axis, 2a...mounting hole, 2c...thickness, 2d...hole 3...Protrusion 4...dental chamber 5…Chip sheet 6…Chip group 10…Thin blade tip 20…Thick blade tip 10a,20a…Blade thickness 10b, 20b... chamfer width 10c…height difference 11,21...First scoop face 12, 12a, 12b, 22, 22a, 22b... Second scoop face 13,23...First escape route 14, 14a, 14b, 24, 24a, 24b…Second escape route 15, 25... Breaker side 16,26…Left side 17,27…Right side 11a, 21a... First cutting edge 12c, 22c... Second cutting edge 11b, 21b…First inner ridge line 12d,22d…Second inner ridge line 11c, 21c... rake angle 11d, 21d... escape angle 12e, 22e… Chamfer angle 12f, 22f... horizontal rake angle 11e, 21e…(Radial width of the rake face) 16a, 17a, 26a, 27a… Claw angle 16b, 17b, 26b, 27b… Side relief angle 16c, 17c, 26c, 27c… Claw 31, 32… Chip 31a, 31b, 31c, 31d, 31e, 31f, 32a, 32b, 32c, 32d, 32e… Cutting edge line L1… Radial line, L2… Circumferential line

Claims

1. It is a circular saw blade, A disc-shaped base metal, The base metal has thin blade tips and thick blade tips that are alternately joined to the outer circumference, Both the thin blade tip and the thick blade tip have a first rake face with a negative rake angle in the center in the thickness direction, and a pair of second rake faces with a negative rake angle and a negative transverse rake angle on both sides in the thickness direction, and which are inclined radially inward of the base metal from both ends of the first rake face in the thickness direction. The thin blade tip is a circular saw blade that is thinner in thickness than the thick blade tip and protrudes radially outward more than the thick blade tip.

2. A circular saw blade according to claim 1, Both the thin blade tip and the thick blade tip have a first relief surface connected to the first cutting edge at the radially outer end of the first rake face, a second relief surface connected to the second cutting edge at the radially outer end of the second rake face, and a breaker surface connected to the first inner ridge at the radially inner end of the first rake face and the second inner ridge at the radially inner end of the second rake face. The first cutting edge and the first inner ridge are substantially parallel, and the second cutting edge and the second inner ridge are substantially parallel, A circular saw blade in which the first rake face and the second rake face intersect at both ends of the first rake face.

3. A circular saw blade according to claim 1 or 2, A circular saw blade in which the radial height difference between the thin blade tip and the thick blade tip is 0.10 mm to 0.25 mm.

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