JP6628677B2 - Cutting insert, tip holder, cutting tool set - Google Patents

Description

  The present invention relates to a cutting tip, a tip holder, and a cutting tool set which are particularly effective for thread cutting of a double threaded body.

  Conventionally, as a cutting tip (tip, bite) for cutting a screw, a throw-away tip (throw-away bite) has been used particularly for mass production by an NC lathe (see Patent Document 1).

  FIG. 23 (A) shows an example of a throw-away insert for thread cutting and its holder. FIG. 23A is a top view of a state in which the threading insert for cutting is attached to a holder. In this case, the throw-away tip 130 is screwed to the tip holder 120, and when the cutting edge is worn or broken, the throw-away tip 130 is not reground and is disposable. In the case of fixing to the dedicated chip holder 120, it is not necessary to adjust the center height again. Therefore, the exchange is easy and efficient especially when mass production is performed with an NC lathe or the like.

  FIG. 23B is a perspective view of the throw-away tip 130 alone. The thickness B of the tip is usually 1 cm or less, and the tip is mounted with the cutting edge protruding from the outer periphery of the tip holder 120.

JP-A-8-257837

  However, in order to perform accurate cutting, a cutting tip and a tip holder (bite holder) capable of cutting with less chatter than before are required. Also, for example, in a conventional threading cutting tip or the like, the cutting tip as a whole has a three-point blade structure having a substantially triangular apex portion as a cutting edge in plan view, and a root of each blade portion. The portion is provided with a V-shaped notch-shaped flat blade structure, which limits the shape of the thread to be formed and the dimensions. Therefore, it is necessary to replace the tip for each dimension or for each nominal diameter. There has been a problem that a thread shape or the like formed by a very small amount of wear of the cutting edge at the time of machining changes every moment, and a precise thread shape or the like cannot be continuously cut and formed. In view of such circumstances, the present invention has high positioning accuracy of the cutting edge, is unlikely to generate chatter even when the cutting resistance is high, and while expanding the target nominal diameter and dimensional range that can be supported by one cutting tip, An object of the present invention is to provide a cutting tip (tip) and a tip holder capable of continuously cutting a thread shape and the like with high precision even if worn every moment.

The present invention for solving the above-mentioned problems is a cutting tip for performing a cutting process on an external workpiece that moves relatively, and has a columnar main body, and a blade portion provided at an end of the main body and having a cutting edge, The main body has a partial cylinder or a columnar region having a virtual central axis parallel to the main body longitudinal direction, respectively, on peripheral surfaces located on both outer sides in the width direction of the rake face of the blade edge, A pair of inclined surfaces extending in the longitudinal direction of the main body are formed on a peripheral surface located on at least one of both outer sides in a relative rake direction of the cutting edge with a bottom formed in an arc or a plane interposed therebetween. It is a cutting tip.

  In relation to the cutting tip, the present invention is characterized in that the pair of inclined surfaces are more radially than an arc trajectory on an extension of a partial arc that has a cross section orthogonal to the longitudinal direction of the main body of the partial cylinder or columnar region. It is characterized by being formed inside.

  In relation to the cutting tip, in the present invention, the pair of inclined surfaces are formed symmetrically with respect to a reference line extending in the relative rake direction from the tip of the cutting edge when viewed from the longitudinal direction of the main body. It is characterized by the following.

  In relation to the cutting tip, the present invention is characterized in that the centers of curvature of at least one pair of the partial cylinders or the cylindrical regions coincide with each other.

  The present invention relates to the cutting tip, wherein the blade portion is formed at one end in the longitudinal direction of the main body, and the main body is engaged with an external member and one of the longitudinal direction of the main body. It has a possible positioning surface.

  In relation to the cutting tip, in the present invention, the blade portion is formed at each of both ends in the longitudinal direction of the main body, and the main body can be engaged with an external member and one of the longitudinal directions of the main body. It has a first positioning surface, and a second positioning surface that can be engaged with the external member and the other in the longitudinal direction of the main body.

  In relation to the cutting tip, the present invention is configured such that, when viewed from the relative rake direction, the tip of the cutting edge in the blade portion has a symmetric shape with respect to a reference line extending in the longitudinal direction of the main body. Features.

  In relation to the cutting tip, the present invention is characterized in that a front clearance angle of the cutting edge is 10 ° or more.

The present invention that solves the above-mentioned problems is a cutting tool set that combines the cutting tip described in any of the above and a tip holder that holds the cutting tip .
In relation to the cutting tool set, the present invention is characterized in that the tip holder has, at a tip end portion of the holder main body, an accommodation hole for accommodating and holding the cutting tip with a cutting edge exposed. And
In relation to the cutting tool set, the present invention provides that the tip holder has a bolt hole penetrating into the accommodation hole on an outer peripheral surface of the holder body, and the cutting tip is tightened and fixed by a bolt. Features.
In relation to the cutting tool set, the present invention provides the tip holder, wherein the holder body has a hole for extruding the cutting tip toward a cutting edge of the cutting tip in a direction parallel to an axis of the accommodation hole. It is characterized by having.
In relation to the cutting tool set, the present invention provides the tip holder, wherein a lower jaw portion receiving a blade portion of the cutting tip is continuous with a lower surface of the accommodation hole, and a tip of the holder body. The cutting tip is formed so as to protrude from the portion in the longitudinal direction of the cutting tip.
In relation to the cutting tool set, the present invention is characterized in that the tip holder has an axial direction of the accommodation hole perpendicular to a longitudinal direction of the holder main body.
In relation to the cutting tool set, the present invention is characterized in that the tip holder has an axial direction of the housing hole parallel to a longitudinal direction of the holder main body.

  According to the present invention, by combining the cutting tip with a tip holder capable of fixing the cutting tip without loosening, there is an excellent effect that a cutting tool with less chatter and high positioning accuracy of the cutting edge can be provided. In addition, according to the cutting tip or cutting tool of the present invention, while expanding the nominal diameter and the dimensional range that can be handled by one blade portion, the thread shape and the like that are continuously high-precision even if worn every moment. The effect that it becomes possible to perform cutting processing is obtained.

(A) It is a perspective view of a cutting tip concerning a first embodiment of the present invention. (B) It is sectional drawing of the state which combined the cutting tip and chip holder which concerns on 1st embodiment of this invention. (A) It is a top view of the cutting tip concerning the first embodiment of the present invention. (B) It is a bottom view of the cutting tip concerning a first embodiment of the present invention. (C) It is a side view of the cutting tip concerning the first embodiment of the present invention. (A) It is a perspective view of a tip holder concerning a second embodiment of the present invention. (B) In the tip holder concerning a second embodiment of the present invention, it is a sectional view of a portion near the accommodation hole which accommodates a cutting tip in a tip. (C) It is an enlarged view of an accommodation hole of a tip holder concerning a second embodiment of the present invention. (A) It is a top view of a chip holder concerning a second embodiment of the present invention. (B) It is a bottom view of a tip holder concerning a second embodiment of the present invention. FIG. 4C is a cross-sectional view of the tip holder according to the second embodiment of the present invention, taken along line CC ′ in FIG. (A) It is a perspective view of the state where the cutting tip concerning a first embodiment of the present invention was inserted in the tip holder. (B) It is sectional drawing in the state where the cutting tip which concerns on 1st embodiment of this invention was inserted in the tip holder. It is an explanatory view explaining a series of flows at the time of pushing out a cutting tip concerning a first embodiment of the present invention from a tip holder, and taking out. (A) It is a side view of a chip holder for female screw processing concerning a fourth embodiment of the present invention for fixing a cutting tip at the time of female screw cutting. (B) It is an enlarged view of the accommodation hole which accommodates a chip for cutting in a chip holder for internal thread processing. (C) It is sectional drawing of CC 'arrow in FIG. 7 (A) of the front-end | tip part for female screw processing. (A) It is a perspective view of the state where a cutting tip was inserted in a tip holder for female threads concerning a fifth embodiment of the present invention. (B) It is the BB 'arrow sectional drawing in FIG.8 (A) of the cutting tool set which is 5th Embodiment of this invention. It is an explanatory view explaining a series of flows at the time of pushing out a cutting tip from a female screw processing tip holder in a cutting tool set concerning a fifth embodiment of the present invention, and taking it out. (A) It is a side view of the male screw part of both screw bodies. (B) It is explanatory drawing of a screw thread when an external thread body is seen in the perpendicular direction of the center axis of a screw. It is (A) front view of the fastening structure of the male screw body and the female screw body cut with the cutting tool of this embodiment, and is a (B) plan view. It is the (A) front sectional view of the same fastening structure, and is a (B) side sectional view. (A) is a front cross-sectional view of the female screw body, and (B) is a front cross-sectional view of the female screw body in which the spiral direction is opposite to that of the female screw body. It is (A) front view of the same male screw body, (B) sectional drawing only of a screw thread, (C) top view. FIG. 3A is a side view of the male screw body, FIG. 3B is a cross-sectional view of only the thread, and FIG. (A) is a sectional view showing an enlarged sectional shape of a thread of the male screw body, and (B) is a sectional view showing an enlarged sectional shape of a thread of the female screw body. (A) is a matrix showing a male screw body for verification used in the screw designing method according to the embodiment of the present invention, and (B) is a female screw body group for verification used in the screw designing method according to the embodiment of the present invention. FIG. It is a figure which shows the aspect of the fastening strength test of the male screw for verification and the female screw for verification. It is a graph which shows the result of the fastening strength test of the same male screw body for verification of the nominal diameter N16, and the same internal thread body for verification. It is a graph which shows the result of the fastening strength test of the same male screw body for verification of the nominal diameter N24, and the same internal thread body for verification. It is a graph which shows the result of the fastening strength test of the male screw body for verification of the nominal diameter N30, and the female screw body for verification. It is a front view sectional view of the conclusion structure of the male screw object and the female screw object concerning other examples. (A) It is a conceptual diagram of the conventional use form of the throw-away tip for thread cutting. (B) It is a perspective view of the conventional throw-away tip for thread cutting.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 9 show an example of an embodiment of the present invention. In the drawings, portions denoted by the same reference numerals represent the same items. Note that in this drawing and the following drawings, some components are appropriately omitted to simplify the drawings. In this drawing and the following drawings, the size, shape, thickness, and the like of members are appropriately exaggerated.

  FIG. 1 illustrates a cutting tip (tip, cutting tool) according to a first embodiment of the present invention. As shown in the perspective view of FIG. 1A, the tip 1 according to the present embodiment includes a main body 3 which is a columnar main body and blades 2L1 and 2L2 which are located at the ends of the main body and have cutting edges. You. As a material of the chip 1, a cemented carbide having an excellent balance between hardness and stickiness is preferable. Other materials include high-speed steel and cermet, and the blade may be coated with, for example, diamond, DLC, DIA, DG, TiC, TiN, TiCN, TiAlN, CrN, SiC, or the like.

  Partial cylindrical regions 3A each having an imaginary central axis parallel to the chip body longitudinal direction Y are formed on peripheral surfaces located on both outer sides in the width direction X of the rake face 2A of the cutting edge 2B of the main body 3 (FIG. 1 (B)), a pair of inclined surfaces 4 extending in the longitudinal direction Y of the chip main body are formed on the peripheral surface of the chip main body located on at least one of both outer sides in the relative rake direction X of the cutting edge 2B. The centers of curvature C of the pair of partial cylindrical regions 3A coincide with each other.

  FIG. 1B shows a cross-sectional view of a state in which the chip 1 and a holder for housing the chip are combined. The pair of inclined surfaces 4 are formed in the chip main body 3 in a direction opposite to the relative rake direction Z. Since the pair of inclined surfaces 4 are formed radially inward of the arc trajectory 3B on the extension of the partial arc that has a cross section orthogonal to the chip body longitudinal direction Y of the partial cylindrical region 3A, a so-called commercially available completed surface is formed. The chip 1 according to the present embodiment can be easily formed by grinding a round bit. In the cross-sectional view of FIG. 1B, for convenience, a chip receiving hole of the chip holder is shown outside the chip 1, but the inner periphery of the chip receiving hole and the outer periphery of the chip 1 have substantially the same shape. As described below, the position of the cutting edge 2B of the chip 1 is accurately determined with respect to the holder 5 by the contact between the inclined surface (not shown) of the chip holder of the chip housing hole and the inclined surface 4 of the chip 1.

  2A shows a top view of the chip 1 according to the embodiment of the present invention, FIG. 2B shows a bottom view of the chip 1, and FIG. 2C shows a side view of the chip 1. . The tip 1 has blade portions 2L1, 2L2 formed at both ends in the longitudinal direction L of the tip body. The tip shape of the cutting edge 2B of the blade portions 2L1 and 2L2 is a V-shape that is symmetric with respect to a reference line extending in the longitudinal direction Y of the chip body when viewed from the relative rake direction Z. Of course, although not particularly limited, the cutting edge 2B here has two main cutting blades 2D1, 2D2 symmetrically.

  In FIG. 2 (A), the rake face 2A of the blade portions 2L1 and 2L2 is not particularly provided with a structure. However, in order to treat chips generated when the work is cut in the turning process, grooves and projections are formed. A structure may be provided to provide a chip breaker. Although no structure is provided on the upper surface of the main body 3 in FIG. 2A, a horizontal plane extending in the longitudinal direction Y of the chip main body is formed, and a vertically downward force is transmitted when the chip 1 is tightened and fixed from above. It is also possible to adopt a configuration in which the cause of chattering and the like is further eliminated so as to be easily performed.

  As shown in the bottom view of FIG. 2B, a bottom 6 is provided between the pair of inclined surfaces 4. The cross section of the bottom 6 is formed as an arc locus 3B (see FIG. 1B) on an extension of the partial arc. Therefore, the chip 1 is inserted into the chip accommodating hole 35 of the holder while being guided in the longitudinal direction L of the main body by the bottom portion 6, and is formed by the pair of inclined surfaces 4 and the inclined surfaces of the chip holder 5 with respect to the rotating spindle of the cutting device. The blade portions 2L1 and 2L2 are accurately positioned in orthogonal directions (here, the width direction X of the rake face 2A and the relative rake direction Z). The bottom surface 6 may have a plane extending in the longitudinal direction Y of the chip body.

  As shown in FIG. 2C, between the cutting edge 2B and the main body 3, a first positioning surface 15L1, which can be engaged with an external member (specifically, a chip holder) and one of the chip main body longitudinal directions Y, And the 2nd positioning surface 15L2 which can be engaged with an external member and the other of the main body longitudinal direction Y is formed. When the positioning surfaces 15L1 and 15L2 abut on the holder-side positioning surface 60 provided in the chip housing hole 35 of the chip holder 25, which will be described later, the work of the chip 1 in the chip body longitudinal direction Y due to the back force of the cutting resistance. And the displacement in the opposite direction can be prevented.

  In addition, the front clearance angle A of the cutting edge 2B is set to 10 ° or more in order to prevent interference with a workpiece when a female screw hole described later is formed. The height of the positioning surfaces 15L1 and 15L2 (the height here is along the relative rake direction Z, but the height direction differs depending on the position where the positioning surfaces 15L1 and 15L2 are formed) is determined by the main body. It is preferably set to 40% or less of the maximum outer dimension of the portion 3 in the same height direction, and more preferably to 25% or less. Similarly, the height of the positioning surfaces 15L1, 15L2 is preferably set to 50% or less of the maximum outer dimension of the height of the blade portions 2L1, 2L2 in the same direction, and more preferably, to 30% or less. In any case, by setting the height of the positioning surfaces 15L1 and 15L2 small, it is possible to secure a large height in the same direction of the blades 2L1 and 2L2, and to greatly increase the rigidity of the blades 2L1 and 2L2. Can be.

  FIG. 3 illustrates a tip holder (bite holder) according to a second embodiment of the present invention.

FIG. 3A is a perspective view of a tip holder 25 according to the second embodiment of the present invention.
The tip holder 25 mainly includes a pillar-shaped shank 27, a tip receiving hole 35 at an end of the shank 27, a lower jaw 40 provided below the tip receiving hole 35, a bolt hole 30 for a fastening bolt, and the like. The cutting tool set is configured by inserting and fixing the chip 1 according to the first embodiment of the present invention into the chip housing hole 35. At this time, as shown in FIG. 4C, the lower end 2C of the cutting edge 2B of the tip 1 is supported by the protruding end 40B of the support surface 40A of the lower jaw 40. With this support structure, the tip 1 can be prevented from being displaced by the main component, which is the vertical component of the cutting resistance. The support surface 40 </ b> A of the lower jaw 40 is formed continuously from the lower surface of the chip receiving hole 35 in the axial direction L and further projects from the shank 27.

  FIG. 3B is a cross-sectional view of a tip end portion of the tip holder 25 according to the second embodiment of the present invention in a direction orthogonal to the axial direction L of the tip holder main body. An enlarged view of the chip receiving hole 35 is shown in FIG. Assuming that a chip is inserted into the chip receiving hole 35, a partial cylindrical region 42A is formed on the inner peripheral surface located on both sides in the width direction X of the virtual rake surface of the chip. The center of curvature of the partial cylindrical region 42A coincides with the virtual center axis C that is parallel to the axial direction of the chip receiving hole 35. A pair of inclined surfaces 45 extending parallel to the virtual center axis C of the chip receiving hole 35 are formed on the inner peripheral surface located on at least one of both sides in the relative rake direction H. The pair of inclined surfaces 45 are, in a cross section orthogonal to the virtual center axis of the partial cylindrical region 42A formed on the inner periphery of the chip receiving hole 35, more radially than the partial arc trajectory 42B which is an extension of the partial cylindrical region 42A. Formed inside. The inclined surface 45 of the chip holder is formed symmetrically with respect to the virtual center axis of the chip receiving hole 35, and the centers of curvature of the pair of partial cylindrical regions 42A coincide with the virtual center axis C. Further, the chip holder 25 according to the second embodiment has a bolt hole 30 penetrating from the outer peripheral surface of the shank portion 27 to the chip receiving hole 35 at a position facing the inclined surface 45 of the chip receiving hole 35. The chip 1 is tightened and fixed by screwing a tightening screw 70 from the outside into the bolt hole 30 and projecting into the chip housing hole 35.

  FIG. 4A shows a top view of the tip holder 25 according to the second embodiment of the present invention. At the axial end of the shank 27, a lower jaw 40 is provided so as to protrude. The lower jaw 40 supports the lower portion 2C of the cutting edge 2B of the tip 1 in the direction in which the cutting edge 2B moves with respect to the workpiece. In the vicinity of the axial end of the shank 27, a bolt hole 30 and a tip extrusion hole 50 are provided. Note that the extrusion hole 50 may be a hole having a polygonal cross section, or a screw hole, other than a hole having a circular cross section. FIG. 4C is a cross-sectional view taken along the line CC ′ of FIG. A holder-side positioning surface 60 is provided inside the chip receiving hole 35, and by contacting the positioning surface 15 L 1 or 15 L 2 of the chip 1 inserted into the chip receiving hole 35, the cutting edge 2 B of the chip 1 becomes longer in the longitudinal direction of the chip 1. It is positioned in the direction Y.

  FIG. 5A is a perspective view showing the vicinity of the tip of a cutting tool set including a combination of the tip 1 and the tip holder 25 according to the third embodiment of the present invention. The tip 1 is inserted into the tip accommodating hole 35 of the tip holder 25, and is fixedly fastened by the fastening screw 70 in a state where the lower portion 2C of the cutting edge 2B is supported vertically upward (relative rake direction H) by the lower jaw portion 40. The tip holder 25 is fixed to a tool rest (not shown) of a device for performing a thread cutting process, and a cutting process is enabled. When the chip 1 is missing or worn, it is replaced.

  FIG. 5B is a sectional view of a cutting tool set. When the positioning surface 15L1 of the chip 1 and the holder-side positioning surface 60 of the chip holder 25 are in contact with each other, the chip 1 is positioned in the longitudinal direction L of the chip 1. The chip 1 is fixed by the bolt holes 30 and the fastening screws 70. In FIG. 5B, the front clearance angle A of the cutting edge 2B of the tip 1 and the clearance angle of the ridge 40C of the lower jaw 40 at the tip of the tip holder 25 are equal, but may be different. However, in order to prevent chattering of the cutting edge, the lower portion 2C of the cutting edge 2B of the tip 1 is desirably supported vertically upward by a V-shaped lower jaw portion 40, like the lower portion 2C. The lateral clearance angle at the tip of the tip holder 25 is desirably the same as the lateral clearance angle of the chip 1, but may be different.

  In the main body of the tip holder 25, an extrusion hole 50 is provided in the direction parallel to the axis L of the accommodation hole and facing the cutting edge of the cutting tip. However, they need not necessarily be parallel, and it is only necessary that the chips can be pushed out.

  Next, the operation of removing the chip 1 from the chip holder 25 in the third embodiment will be described.

  FIG. 6 is an explanatory diagram illustrating a series of flows when the chip 1 is pushed out of the chip holder 25 and taken out. In the state where the chip 1 is housed in the chip housing hole 35 of the chip holder 25 as shown in FIG. 6 (A), after tightening the tightening screw 70, the push rod 80 is inserted through the push hole 50, and the push rod 80 is inserted. Is hit with a hammer 75 at one end. Then, the chip 1 is pushed out in the direction of the arrow in FIG. 6B, and the chip 1 is taken out from the chip housing hole 35 as shown in FIG. 6C.

  FIG. 7 illustrates a tip holder (bite holder) 87 for processing internal threads according to a fourth embodiment of the present invention. The tip holder 87 is used when the tip 1 is internally threaded. FIG. 7A shows a side view of the tip holder 87. At the end of the chip holder 87, a chip receiving hole 85 is provided in a direction orthogonal to the longitudinal direction L of the main body of the chip holder 87 so as to be continuous with the lower part of the chip receiving hole 85. The lower jaw portion 90 is provided so as to protrude outward in the width direction from the side wall in the longitudinal direction L.

  FIG. 7B is an enlarged view of a cross section orthogonal to the axial direction of the chip housing hole 85 for housing the chip (the width direction W of the chip holder 87). The chip accommodation hole 85 has an inner peripheral surface located on both sides in a virtual width direction X (which coincides with the longitudinal direction L of the main body) of the chip accommodated therein, which is parallel to the axial direction W of the chip accommodation hole 85. A partial cylindrical region 92A having the virtual center axis C is formed. A pair of inclined surfaces 95 extending in a direction parallel to the axial direction W of the chip accommodation hole 85 are formed on the inner peripheral surface of at least one of both sides in the relative rake direction H of the chip accommodation hole 85. The pair of inclined surfaces 95 has a radius larger than a partial arc trajectory 92B which is an extension of the partial cylindrical region 42A in a cross section orthogonal to the virtual center axis C of the partial cylindrical region 92A formed on the inner periphery of the chip housing hole 85. It is formed inside the direction. The inclined surface 95 of the female screw processing chip holder 87 is formed symmetrically with respect to the virtual center axis C of the chip accommodation hole 85, and the center of curvature of the pair of partial cylindrical regions 92A coincides with the virtual center axis C. The female screw processing tip holder 87 according to the fourth embodiment has a bolt hole 100 that penetrates into the chip receiving hole 85 on the outer peripheral surface of the shank portion 88 facing the inclined surface 95, and fastens the chip 1 with a bolt. Fix it.

  FIG. 7C is a cross-sectional view of the tip of the female screw processing tip holder 87 taken along a plane orthogonal to the chip holder main body longitudinal direction L. Although the outer peripheral profile of the cross section in the direction perpendicular to the axis of the female screw processing tip holder 87 is substantially circular, the lower jaw portion 90 is formed to protrude outward in the width direction W (radial direction) with respect to this outer peripheral surface. The lower jaw portion 90 has a structure for supporting the lower portion 2C of the cutting edge 2B of the tip 1 projecting from the outer peripheral surface in a vertically upward direction (upward in the relative rake direction H). The lower jaw portion 90 is provided on a lower extension of the chip receiving hole 85. As described later, the chip 1 is housed in the chip housing hole 85, and the positioning surface 15L1 of the chip 1 is brought into contact with the holder-side positioning surface 105 in the chip housing hole 85, so that the positioning of the chip 1 in the longitudinal direction is accurate. Well done.

  FIG. 8A is a perspective view showing the vicinity of the tip end of a cutting tool set in which the tip 1 is inserted into the tip holder 87 for internal thread machining according to the fifth embodiment of the present invention. A tip accommodation hole 85 is provided at the tip of the tip holder 87 for internal thread processing, into which the tip 1 is inserted. The lower portion 2C of the cutting edge 2B of the tip 1 is supported vertically upward by a lower jaw 90 provided on the outer peripheral surface of the tip holder 87 for female screw machining.

  As shown in FIG. 8 (B), the positioning surface 15L1 of the chip 1 is brought into contact with the holder-side positioning surface 105 in the chip housing hole 85, so that the position of the cutting edge of the chip 1 in the projecting direction is accurately determined, Even during processing, displacement is unlikely to occur in the same protruding direction. That is, the holder-side positioning surface 105 can prevent the tip 1 from shifting due to the back force of the cutting resistance. In addition, the inclined surface 4 of the tip 1 comes into contact with the inclined surface 95 of the tip holder 87 by the tightening screw 110, and the position of the cutting edge in the width direction is accurately determined. Further, since the lower portion 2C of the cutting edge 2B is supported by the lower jaw portion 90, chatter and displacement can be suppressed to a minimum.

  FIG. 9 is an explanatory diagram illustrating a series of flows for taking out the chip 1 from the chip holder 87 for internal thread processing.

  As shown in FIG. 9A, in a state where the chip 1 is housed in the chip housing hole 85 of the female screw processing chip holder 87, the tightening of the tightening screw 110 is loosened, and the cutting is performed through the chip housing hole 85. The flank below the blade portions 2L1 and 2L2 on the side that is not formed (the side opposite to the lower jaw portion 90) is pushed toward the lower jaw portion 90. As a result, the chip 1 is pushed out in the direction of the arrow in FIG. 9B, and the chip 1 is taken out from the chip housing hole 85 as shown in FIG. 9C. In the present embodiment, the female screw processing chip holder 87 is not provided with a dedicated extrusion hole for the chip 1, but is provided with a small-diameter dedicated extrusion hole without penetrating the chip housing hole 85, and is provided with a male screw processing chip holder. As in FIG. 6 at 25, the tip 1 may be pushed out using a push rod 80. In this case, the problem that chips enter from the opening of the through hole of the chip receiving hole 85 which is not on the cutting side is eliminated.

  Next, as one of the fastening structures processed by the cutting tip, the tip holder, and the bite set of the first to fifth embodiments, a so-called male screw body such as a bolt and a so-called female screw body such as a nut are used. I will introduce.

  With regard to the fastening structure using this screw body, two types of spiral grooves (for example, a right male screw part and a left male screw part) having different lead angles and / or lead directions are formed for one male screw body, and these two types of spirals are formed. There is a type in which two types of female screw bodies (for example, a right female screw body and a left female screw body) are separately screwed into a groove like a double nut. If the relative rotation of the two types of female screw bodies is suppressed by some kind of engagement means, mechanical interference between the male screw and the male screw is caused by an axial interference action or an axial separation action caused by different lead angles and / or lead directions. It can provide a locking effect.

  FIG. 10A shows a double threaded body in which two types of spiral grooves (right male thread and left male thread) having different lead directions are formed in one male thread.

  The male screw body 140 is provided with a male screw part 153 having a male screw spiral structure formed from the base side toward the shaft end. In this example, the male screw portion 153 has a first male screw spiral structure 154 serving as a right screw configured to be capable of being screwed with a corresponding female screw spiral thread serving as a corresponding right screw, and a female screw shaped screw member serving as a corresponding left screw. Two types of male screw helical structures including a second male screw helical structure 155 serving as a left-handed screw configured to be capable of screwing a helical thread are formed overlapping on the same region. As shown in FIG. 10 (B), a substantially crescent-shaped screw thread 153a extending in the circumferential direction in a plane direction perpendicular to the axis (screw axis) C is provided on the male screw part 153 on one side of the male screw part 153. It is provided alternately on the left side in the figure) and on the other side (right side in the figure). By configuring the thread 153a in this way, two types of spiral grooves, a spiral structure that rotates clockwise and a spiral structure that rotates counterclockwise, can be formed between the threads 53a.

  In this way, two types of male screw spiral structures, the first male screw spiral structure 154 and the second male screw spiral structure 155, are formed in the male screw body 140. Therefore, the male screw body 140 can be screwed with any of the female screw bodies of the right-hand thread and the left-hand thread.

  In order to realize a fastening structure without looseness with practical strength by using such a double helix structure (both screw bodies), Japanese Patent No. 4663813 and the like, which are the result of earnest research by the present inventors, have been proposed. The special thread described, whose cross section perpendicular to the axis is substantially elliptical, is effective (see FIG. 10B).

  The reference line extending in the longitudinal direction Y of the chip main body when the blade portions 2L1 and 2L2 of the cutting tip 1 according to the first embodiment of the present invention are viewed from the relative rake direction Z in FIG. Symmetrical, that is, providing two main cutting blades 2D1 and 2D2 symmetrically when viewed from the cutting edge means that when two spiral strips having different lead directions are formed, only the feed direction is reversed to cut the screw. Preferred to allow. Specifically, this shape enables finishing with radial infeed. However, since the method of infeed is not limited to radial infeed, the angles of the two main cutting edges need not necessarily be the same.

  As described above, the embodiments of the cutting tip and the tip holder according to the present invention have been described. However, the present invention is not limited to the described embodiments, and various modifications can be made within the scope described in each claim. It is possible. For example, in FIG. 4 (B) and the like, the chip housing hole 35 is expressed as being provided in a direction parallel to the longitudinal direction L of the chip holder 25 main body with respect to the main body of the chip holder 25, but is inclined in the vertical direction. May be. Further, although the tip housing hole 85 of the female screw processing tip holder 87 is shown in FIG. 7A as being provided in a direction orthogonal to the longitudinal direction L of the female screw processing chip holder 87 main body, the present invention is not limited to this.

  Next, the angle of the cutting edge 2B of the tip 1 applied when cutting a screw body will be described. Since the angle of the cutting edge 2B is determined by the thread angle of the screw body, the thread angle of the screw body will be described here.

<Male and female threads>
As shown in FIGS. 11 and 12, the fastening structure 1001 of the male screw body 1010 and the female screw body 1100 to be processed is formed by screwing the female screw body 1100 to the male screw body 1010.

  As shown in FIGS. 14 and 15, the male screw body 1010 is provided with a male screw part 1013 in which a male screw spiral groove is formed from the base side of the shaft part 1012 toward the shaft end. In the present embodiment, the male screw portion 1013 is provided with a first screw groove 1014 serving as a right screw configured to be capable of being screwed with a corresponding female screw spiral thread serving as a right-hand screw, and a female screw-shaped screw driver serving as a corresponding left screw. Two types of male screw spiral grooves, such as a left spiral screw 1015 which is a left-hand screw configured to be able to screw a spiral strip, are formed so as to overlap on the same region in the axial direction of the male screw body 1010. In addition to the overlapping portion, a single spiral groove region in which a spiral groove in one direction is formed may be provided.

  The first helical groove 1014 can be screwed with a corresponding female threaded helical thread serving as the right-hand thread of the corresponding female screw body 1100, and the second helical groove 1015 can be screwed with the corresponding female screw body 1100 (which is (Including a female screw body having a right-hand thread and a separate screw) (see FIG. 1).

  As shown in FIGS. 14C and 15C, the male screw portion 1013 has a substantially crescent-shaped thread extending in the circumferential direction in a plane perpendicular to the axis (screw axis) C. The ridges G are provided alternately on one side (the left side in the drawing) and the other side (the right side in the drawing) in the diametric direction of the male screw portion 1013. That is, the thread G has its ridge line extending perpendicular to the axis, and the height of the thread G changes so that the center in the circumferential direction is higher and both ends in the circumferential direction are gradually lower. By configuring the thread G in this manner, a virtual spiral groove structure that turns clockwise (see an arrow 1014 in FIG. 14A) and a virtual spiral groove structure that turns counterclockwise (see FIG. Two types of spiral grooves (see arrow 15 in A)) can be formed between the threads G.

  In the present embodiment, in this manner, two types of male screw spiral grooves, the first spiral groove 1014 and the second spiral groove 1015, are formed so as to overlap the male screw portion 1013. Therefore, the male screw portion 1013 can be screwed with any of the right-handed screw and the left-handed screw. For details of the male screw portion 1013 in which two types of male screw spiral grooves are formed, refer to Japanese Patent No. 4663813 according to the inventor of the present application.

  As shown in FIG. 13A, the female screw body 1100 includes a tubular member 1106. The cylindrical member 1106 has a so-called hexagonal nut shape, and has a through hole 1106a at the center. Of course, the general shape of the female screw body 1100 is not limited to a hexagonal nut shape, but can be arbitrarily set as appropriate, such as a cylindrical shape, a shape having knurls on the peripheral surface, a square shape, and a star shape. A first female screw spiral thread 1114 as a right-hand thread is formed in the through hole 1106a. That is, the first female screw spiral strip 1114 of the tubular member 1106 is screwed with the first spiral groove 1014 of the male screw portion 1013 of the male screw body 1010.

  As shown in FIG. 13B, as the female screw 1101, a second female screw spiral strip 1115 as a left-hand thread may be formed in the through hole 1106a. In this case, the second female screw spiral strip 1115 is screwed with the second spiral groove 1015 in the male screw portion 13 of the male screw body 1010.

  Next, with reference to FIG. 16 (A), a description will be given of a shape of a cross section along the axial direction of a thread G formed in the male screw portion 1013 of the male screw body 1010 when viewed in the direction perpendicular to the axis.

  Further, the shape of the thread P of the first female screw spiral strip 1114 of the female screw body 1100 and / or the shape of the thread P of the second female screw spiral strip 1115 of the female screw body 1101 shown in FIG. Since they are set relative to each other, a detailed description is omitted here.

  Furthermore, the nominal diameter of the male screw body 1010 of the present embodiment will be referred to by adding N to the initials. For example, in the case of the male screw body 1010 of N16, the diameter F at the vertex Gt of the thread G is 16 mm, and in the case of the female screw body 1100 of N16, the diameter of the root of the thread is 16 mm. means.

  The ridge angle T of the thread G (the ridge angle means an angle formed by a pair of slopes extending from the top of the thread G toward the valley) is set to a range of 61 ° or more and 75 ° or less, More preferably, it is set in the range of 65 ° or more and 73 ° or less, more preferably, it is set in the range of 67 ° or more and 73 ° or less, and more specifically, it is set in the range of 70 °. In addition, the root diameter D of the thread G (that is, the outer diameter when the thread G is omitted in the shaft portion 1012 of the male screw body 1010) is set to 13.5 mm or more and 14.3 mm or less in the case of N16. Is preferred. The valley diameter D in the case of N16 is preferably set to 13.5 mm or more and 14.3 mm or less. It is preferable that the valley diameter D in the case of N24 is set to 19.6 mm or more and 20.5 mm or less. The valley diameter D in the case of N30 is preferably set to 25.8 mm or more and 26.7 mm or less. The valley diameter here is not the effective diameter of a conventional metric screw thread, but corresponds to the diameter of the valley bottom.

  Accordingly, as shown in FIG. 16 (B), the thread angle P of the thread P is also set in the range of 61 ° or more and 75 ° or less, and more preferably 65 ° or more and 73 ° or less, with respect to the female screw 1100 as well. And more preferably, it is set to be 67 ° or more and 73 ° or less, and more specifically, set to 70 °. Further, it is preferable that the thread diameter E of the apex Pt of the thread P is set to 13.5 mm or more and 14.3 mm or less in the case of N16. The peak diameter E in the case of N16 is preferably set to 13.5 mm or more and 14.3 mm or less. The peak diameter E in the case of N24 is preferably set to 19.6 mm or more and 20.5 mm or less. The peak diameter E in the case of N30 is preferably set to 25.8 mm or more and 26.7 mm or less. Of course, it is needless to say that the setting of the thread diameter of the female screw needs to be set to be equal to or greater than the root diameter of the male screw body.

<Design method and design basis>
Next, the design method and design basis of the male screw body 1010 and the female screw body 1100 will be described below. Here, an example of designing the male screw body 10 having the nominal diameter N16 will be introduced.

<Preparation of series of male screw body 10 and female screw body 100>
First, regarding the male screw body 10 having the nominal diameter N16, as shown in FIG. 17A, a plurality of different root diameters D1, D2,..., Dn and a plurality of different peak angles T1, T2,. A plurality of male screw bodies for verification 10 (Tn, Dn) are prepared so as to fill a part or all of the matrix condition composed of Tn.

  In addition, the same number of female screw bodies for verification 1100 that can be screwed with each of the plurality of male screw bodies for verification 1010 (Tn, Dn) are prepared. That is, as shown in FIG. 17B, a matrix composed of a plurality of different peak diameters E1, E2,..., En and a plurality of peak angles Q1, Q2,. A plurality of female screw bodies for verification 1100 (Qn, En) are prepared so as to fill all or some of the conditions. Specifically, the thread diameter En of the female screw body for verification 1100 (Qn, En) substantially matches the root diameter Dn of the male screw body for verification 1010 (Tn, Dn), and the peak angle Qn is equal to the male thread body for verification 1010. It substantially coincides with the peak angle Tn of (Tn, Dn). As a result, the verification male screw body 1010 (Tn, Dn) and the verification female screw body 1100 (Qn, En) which are present at the same position on the matrix in FIG. 17A and FIG. Many sets are prepared.

  The length W in the axial direction of the female screw body for verification 1100 (Qn, En) (this is also referred to as the axial length W. See FIG. 11) is the same for all the test pieces in the fastening strength test at the nominal diameter N16. And a predetermined ratio γ (0 <γ <1) specific to the material with respect to the nominal diameter N16. That is, in the case of N16, the axial length W of the female screw body for verification 100 (Qn, En) is set to 16 mm × γ. Of course, the value of W is calculated by multiplying each of the nominal diameters by a predetermined ratio of γ, which is a material specific value.

As shown in FIG. 18, the axial hanging length W generally has a tensile strength H that the axial section 1012A of the shaft portion 1012 of the male screw body 1010 can withstand, and a thread of the male threaded body 1010 at the axial hanging length W. A value is selected such that the shear strength S of the peripheral surface J composed of the base surface GL of G (see FIG. 16A) is easily approximated. The tensile strength H is a value obtained by multiplying the sectional area at the valley diameter Dn by the coefficient a1, and can be expressed by H = π × Dn ² × a1. The shear strength S is a value obtained by multiplying a cylindrical area equivalent to the axial length W at the valley diameter Dn by a coefficient a2, and can be expressed by S = π × Dn × W × a2.

  The coefficients a1 and a2 are different depending on the material of the base material and the like, but according to the study of the present inventors, in this embodiment, a general-purpose steel material such as S45C or SCM435 is selected as the base material, and W is set as described above. It has been found that when set as described above, the tensile strength H and the shear strength S are considerably close values. As a result, the fastening strength between the female screw body for verification 1100 (Qn, En) and the male screw body for verification 1010 (Tn, Dn) changes the peak angle T and the root diameter D. Slightly increases or the tensile strength H side slightly increases. Which is superior can be verified by a fastening strength test, and a boundary between the shear strength S superior state and the tensile strength H superior state can be found by an experiment.

  Here, for convenience of explanation, a case where the valley diameter D, the peak angle T, and the like are varied using the matrix shown in FIG. 17 is illustrated. However, in actuality, the verification is performed so as to fill all the locations of the matrix. It is not necessary to prepare the male screw body 1010 (Tn, Dn) and the female screw body for verification 1100 (Qn, En), and it is not necessary to form a matrix. As will be described later, any configuration may be used as long as the optimum value can be extracted by a combination of the male screw body for verification and the female screw body for verification in which the root diameter D and the peak angle T vary within a certain range.

<Boundary valley diameter extraction process>
Next, a pair of the male screw body for verification 1010 (Tn, Dn) and the female screw body for verification 1100 (Qn, En) (hereinafter, referred to as a verification bolt and nut set) are screwed together to perform a fastening strength test. As shown in FIG. 18, in the fastening strength test, the male screw body for verification 1010 (Tn, Dn) and the female screw body for verification 1100 (Qn, En) are relatively displaced in the axial direction (see arrow A). It means a tensile test in which the fastening state (screwed state) is forcibly released by moving, but is not particularly limited to this, and is repeatedly applied to the male screw body 1100 (Tn, Dn) and the female screw body 1100 (Qn, En). In addition to the fatigue test in which the screw is relatively separated from each other, a so-called screw tightening test for verifying the torque, axial force, and rotation angle of the screw body may be performed. Has been confirmed to be. A tightening strength test is performed on all the verification bolt and nut sets, and the result is that the shaft G is broken at the shaft portion 1012 of the male screw body 1100 to release the fastening, or the thread G is deformed or broken. It is determined whether or not the thread break mode in which the fastening is released.

  FIG. 19 shows a graph example of the determination result. In this graph, the horizontal axis is set to the peak angle Tn, the vertical axis is set to the root diameter Dn, and the verification bolt and nut set in the form of broken shaft is indicated by ○, and the verification bolt and nut set in the form of thread break is indicated by Δ. are doing. As can be seen from the results, the graph is bisected into a region X in which a thread break mode occurs (thread break region X) and a region Y in which a shaft break mode occurs (shaft break region Y), and the boundary line K is clearly shown. can do. When the maximum valley diameter value that can cause the axial fracture mode corresponding to a specific peak angle Tk is defined as the boundary valley diameter Dk, the boundary line K has a change in the peak angle Tk and a boundary valley. This means a correlation between changes in the diameter Dk.

  For example, a design concept in which the peak angle T is set to 68 ° and the root diameter D of the shaft portion is 14.1 mm or more belongs to the thread break region X, and therefore, it is difficult to obtain a shaft break mode when the fastening is released by a tensile test. This means that there is a high possibility that a screw thread collapse form will occur, and this can be considered as a design in which the strength of the shaft is wasted. On the other hand, the design concept in which the peak angle T is set to 68 ° and the valley diameter D of the shaft portion is set to 13.6 mm is easy to obtain a shaft fracture form when the fastening is released, but the boundary valley diameter Dk is about 14.05 mm. Therefore, within this range, the valley diameter D of the shaft portion can be set to be larger and the tensile strength can be increased, which means that the design is inefficient.

  Paradoxically, from this boundary line K, the allowable range of the boundary peak angle Tk (this is defined as the boundary peak angle area Ts) in which the male screw body can be made into the axially broken form in accordance with the change of the boundary trough diameter Dk. Call).

<Shaft breaking superior thread angle selection process>
After the boundary valley diameter extracting step is completed, a ridge angle (hereinafter referred to as a shaft break superior ridge angle Tp) at which the boundary valley diameter Dk becomes a maximum value is selected from the boundary line K. In the graph of FIG. 19, from the peak value of the boundary line K, the dominant peak angle Tp at the axis break is 70.5 °. Even when the shaft portion is made as thick as possible to increase the tensile strength, the shaft breaking superior ridge angle Tp is such that the shearing strength S on the ridge G side which is easy to lead to the shaft breaking form with respect to the release of the fastening, that is, the shear strength S on the ridge G side is the highest. It can be described as an easy mountain angle.

<Thread angle determination process>
Finally, a design is performed by applying the crest angle approximate to the determined shaft break superior crest angle Tp to the actual male screw body 1010 and / or female screw body 1100 at the nominal diameter N16. For example, if the actual peak angle T is set to 70 °, the valley diameter D can be set large. As a specific valley diameter D, for example, about 14.25 mm is preferable.

  In FIG. 19, the design method in the case of the nominal diameter N16 has been described, but the present invention is not limited to this, and another nominal diameter may be used. For example, FIG. 20 shows a graph of the verification result in the case of the nominal diameter N24, and FIG. 21 shows a graph of the verification result in the case of the nominal diameter N30. What can be said in common to these graphs is that the axial break superior mountain angle Tp is in the range of 65 ° or more and 75 ° or less, more preferably in the range of 67 ° or more and 73 ° or less, and is approximately 70 °. Before and after. That is, in the case of the male screw body 1010 having the structure of the present embodiment, the thread angle of the thread is not 60 ° which is common sense in the related art, but a larger value is suitable, and the optimum value is around 70 °. You can see that.

  In the male screw body 1010 and the female screw body 1100, the pair of the first spiral groove 1014 and the female screw spiral strip 1114 and the pair of the second spiral groove 1015 and the female screw spiral strip 1115 have a reverse screw relationship (lead angle). Are the same and the lead directions are opposite), but the present invention is not limited to this. For example, as shown in FIG. 22, the first spiral groove 1014 and the female screw spiral strip 1114 having the same lead direction (L1, L2) and different lead angles, and the second spiral groove 1015 and the female screw spiral strip 1115 may be employed. it can. In this case, by forming a spiral groove having a different lead angle further on the first spiral groove 1014, the first spiral groove 1014 having the lead L1 (lead angle α1) and the lead L2 (lead angle α2). The second spiral groove 1015 is formed with the screw directions aligned. In this case, since the first thread G1 of the first spiral groove 1014 and the second thread G2 of the second spiral groove 1015 are not shared but are separate, at least one of the threads G1 and G2. The present invention may be applied, or may be applied to both. Of course, the thread angle of the first thread G1 and the thread angle of the second thread G2 may be different from each other.

  In the above-described embodiment, the case of the male screw body 1010 having the double helix structure is exemplified. However, the present invention is not limited to this, and the male screw body 1010 having the single helix structure can be optimized by applying the above design procedure. Can be determined theoretically and / or experimentally.

  As a result, the angle I and the shape of the cutting edge 2B of the tip 1 may be set so that the thread can be machined. For example, the angle I may be substantially equal to the "thread angle T" or It is preferable to set smaller. In the case where the insert 1 is cut while the cutting edge is brought into contact with the base material, the angle J of the cutting edge on one side may be set to の of the angle I with respect to the direction perpendicular to the axis.

  The features of the screw body and the ridge angle will be described below.

  (1) A shaft portion, a first spiral groove formed on the peripheral surface of the shaft portion and set at an appropriate lead angle and / or lead direction, and a shaft formed on the peripheral surface of the shaft portion and forming the lead angle and And / or a second spiral groove set at a different lead angle and / or a lead direction with respect to the lead direction, wherein the first spiral groove and the second spiral groove are in the axial direction of the shaft portion. It has a thread portion formed in a strip shape by being superimposed on the same region, and the thread portion is viewed from the top of the thread when viewing a cross section along the axial direction perpendicular to the axis. A male screw body characterized in that a mountain angle formed by a pair of slopes extending toward a valley is set to 61 ° or more and 75 ° or less.

  (2) The ridge angle is set to 73 ° or less in relation to the male screw body.

  (3) The ridge angle is set to 63 ° or more in relation to the male screw body.

  (4) The ridge angle is set in a range of 70 ° ± 3 ° in relation to the male screw body.

  (5) A female thread portion having a female thread portion, wherein the female thread portion constituting the female thread portion extends from the top of the thread of the female thread portion toward the trough when viewed in the direction perpendicular to the axis in a cross section along the axial direction. A female screw body characterized in that a mountain angle formed by the slope is set to 61 ° or more and 75 ° or less.

  (6) In relation to the female screw body, the female screw body is configured to be screwable with any of the male screw bodies described above.

  (7) The male screw body for verification using a plurality of male screw bodies for verification in which the nominal diameter is constant and the peak angle and the valley diameter are different, and a plurality of female screw bodies for verification screwed with the male screw body for verification. In the case of performing a fastening strength test in which the female screw body for verification is screwed into the axial direction and relatively disengaged in the axial direction, the male screw body for verification is broken at the shaft portion to release the fastening state, and the shaft break form, and By causing the destruction of both forms of the thread collapse form in which the fastening state is released by the deformation or shearing of the thread of the male screw body for verification, it can be near the boundary between the shaft fracture form and the thread collapse form. For the valley diameter (hereinafter referred to as a boundary valley diameter), a boundary valley diameter is extracted based on the peak angle variation, and the boundary valley diameter is maximized based on the boundary valley diameter change degree. Can be a value A shaft break dominant crest angle selecting step of selecting the constant crest angle (hereinafter referred to as a shaft break dominant crest angle); and a crest angle approximate to the shaft break dominant crest angle, the actual male screw body at the nominal diameter. And / or a thread angle determining step applied to the female screw body.

  (8) In connection with the screw body design method, the boundary valley diameter extracting step includes: a plurality of the male screw bodies for verification, wherein the ridge angle and the nominal diameter are constant and the valley diameters are different; In the case where a plurality of the verification internal thread bodies to be screwed with the verification external thread body is used, and the fastening strength test is performed in which the verification internal thread body is screwed to the verification external thread body and relatively separated in the axial direction, the verification is performed. In this case, the external thread body is broken at the shaft part to release the fastening, and the verification external thread body is deformed or sheared to break the thread and break the thread. The individual boundary trough diameter extraction step of extracting a specific trough diameter (hereinafter, referred to as a boundary trough diameter) that can be near the boundary between the shaft fracture mode and the thread break mode by causing Select the peak angle, Based on the angle, the By repeating individual boundary valley 径抽 out process, characterized in that it and a step of extracting the degree of change of the boundary root diameter due to the mountain angle variable.

  (9) A male screw body designed based on the above screw body design method.

  (10) A female screw body designed based on the above screw body design method.

  (11) A thread structure applied to a male screw body and / or a female screw body, wherein a pair of slopes extending from the top to the bottom of the thread in the thread structure has a thread angle of 61 ° or more and A thread structure characterized by being set to 75 ° or less.

DESCRIPTION OF SYMBOLS 1 Chip 2L1, 2L2 Blade part 3 Main body part 4 Inclined surface 25 Chip holder 15L1, 15L2 Positioning surface 25 Chip holder 27 Shank part 30 Bolt hole 35 Chip accommodating hole 40 Lower jaw part 45 Inclined surface 50 Extrusion hole 60 Holder side positioning surface 70 Tightening screw 75 Hammer 80 Push rod 85 Chip receiving hole 87 Tip holder 90 Lower jaw 95 Inclined surface 100 Bolt hole 105 Holder side positioning surface 110 Tightening screw 120 Chip holder 130 Throw away tip 140 Male screw

Claims (15)

A cutting tip for performing cutting on a relatively moving external work,
A columnar body,
A blade portion provided at an end of the main body and having a blade edge,
The main body is
On the peripheral surface located on both outer sides in the width direction of the rake face of the cutting edge, a partial cylindrical or columnar region having a virtual central axis parallel to the longitudinal direction of the main body is formed, respectively.
A pair of inclined surfaces extending in the longitudinal direction of the main body are formed on a peripheral surface located on at least one of both outer sides in the relative rake direction of the cutting edge, with a bottom formed in an arc or a plane interposed therebetween.
A cutting tip characterized by the above-mentioned.   The pair of inclined surfaces are formed radially inward of an arc locus on an extension of a partial arc that is a cross section of the partial cylinder or the columnar region and that is orthogonal to the longitudinal direction of the main body. 2. The cutting tip according to 1.   The said pair of slopes are formed symmetrically with respect to the reference line extended in the said relative rake direction from the front-end | tip of the said cutting edge when it sees from the said main body longitudinal direction, The Claim 1 or Claim 2 characterized by the above-mentioned. The described cutting tip.   The cutting tip according to any one of claims 1 to 3, wherein the centers of curvature of at least a pair of the partial cylinders or the cylindrical regions coincide with each other. The blade portion is formed at one end in the longitudinal direction of the main body,
The cutting tip according to any one of claims 1 to 4, wherein the main body has a positioning surface that can be engaged with an external member and one of the main body in the longitudinal direction. The blades are formed at both ends in the longitudinal direction of the main body, respectively.
The main body has an external member and a first positioning surface that can be engaged with one of the main body longitudinal direction, and a second positioning surface that can be engaged with the external member and the other of the main body longitudinal direction. The cutting tip according to any one of claims 1 to 4, characterized in that:   The tip of the cutting edge of the blade portion has a symmetrical shape with respect to a reference line extending in the longitudinal direction of the main body when viewed from the relative rake direction. A cutting tip according to item 1.   The cutting tip according to any one of claims 1 to 7, wherein a front clearance angle of the cutting edge is 10 ° or more. A cutting tool set comprising a combination of the cutting tip according to any one of claims 1 to 8 and a tip holder for holding the cutting tip . The cutting tool set according to claim 9, wherein the tip holder has an accommodation hole at an end of the holder main body for accommodating and holding the cutting tip in a state where a cutting edge is exposed. The cutting tool set according to claim 10, wherein the tip holder has a bolt hole that penetrates into the housing hole on an outer peripheral surface of the holder body, and the cutting tip is fastened and fixed by a bolt. 12. The tip holder according to claim 10, wherein the holder main body includes a hole for pushing out the cutting tip in a direction parallel to an axis of the accommodation hole toward a cutting edge of the cutting tip. Cutting tool set described in 1. The tip holder is formed such that a lower jaw portion for receiving a blade portion of the cutting tip is continuous with a lower surface of the accommodation hole and protrudes from a tip end of the holder body in a longitudinal direction of the cutting tip. The cutting tool set according to any one of claims 10 to 12, characterized in that: The cutting tool set according to any one of claims 10 to 13, wherein in the tip holder, an axial direction of the housing hole is perpendicular to a longitudinal direction of the holder body. The cutting tool set according to any one of claims 10 to 13, wherein the tip holder has an axial direction of the housing hole parallel to a longitudinal direction of the holder main body.

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