JP4744177B2 - Turning tool - Google Patents

Description

The present invention relates to a milling tool comprising a cutting insert and the chip holder constituting the milling tool, about the milling tool comprising a cutting insert and the chip holder constitutes an end mill having a particularly small diameter.

  FIG. 9 is a plan view showing a conventional throw-away end mill 1. FIG. 10 is a cross-sectional view of the throw-away end mill 1 as seen from the section line S10-S10 in FIG. The throwaway end mill 1 includes a tip holder 2 formed in a substantially cylindrical shape, and a throwaway tip 3 that can be attached to and detached from the tip holder 2. The throw-away tip 3 (hereinafter simply referred to as a tip) has a cutting edge for cutting a work material. When the cutting edge of the chip 3 to be mounted is worn, the chip 3 having the worn cutting edge is removed and the chip 3 having a new cutting edge is mounted. The chip holder 2 is formed with a mounting portion 5 that accommodates the remaining portion in the groove 4 formed in the chip holder 2 with a part of the chip 3 protruding. The grooves 4 are formed at equal intervals in the circumferential direction R according to the number of chips 3. The groove 4 is a recess, and a portion between two recesses adjacent in the circumferential direction R is a protrusion 17. In this case, a plurality of convex portions 17 project radially outward from the radially inner portion and are formed at intervals in the circumferential direction R, and the mounting portion 5 is formed on each convex portion 17. That is, each chip 3 is mounted on each convex portion 17.

  The chip 3 is formed in a substantially rectangular parallelepiped shape. Two long sides 7 and 8 that respectively form two long sides of the upper surface 6 that is one surface in the thickness direction of the chip 3, and two short sides 9 that respectively form a short side of the upper surface of the chip 3, 10 are formed with cutting edges 11 and 12, respectively. Further, the bottom surface 13 which is the other in the thickness direction contacts the seating surface 16 of the chip holder 2. The chip 3 is in a state in which one long side portion 7 and one short side portion 9 partially protrude from the chip holder 2 with the seating surface 13 in contact with the chip holder 2. One long side portion 7 protrudes radially outward Y2 from the tip holder 2 as shown in FIG. 10, and one short side portion 9 extends from the tip holder 2 in the axial direction X1 as shown in FIG. Protrusively. Accordingly, the cutting edge 11 of one long side portion 7 of the chip 3 is formed as a main cutting edge, that is, an outer peripheral cutting edge. Further, the cutting edge 12 of one short side portion 9 is formed as a sub cutting edge, that is, a tip cutting edge. Further, the chip 3 mounted on the mounting portion 5 of the chip holder 2 has the other long side portion 8 in contact with the first side surface 14 formed on the mounting portion 5 and the other short side portion 10 formed on the mounting portion 4. Abutted against the second side surface 15.

  Such a throwaway end mill 1 is disclosed in, for example, Patent Document 1 and Patent Document 2. In the chip holder 2 disclosed in Patent Document 1, when the seating surface 13 and the side surfaces 14 and 15 are extended, notched grooves formed by notching the intersecting portions are formed. The depth of the notch groove gradually decreases as it goes inward from the chip holder surface. Further, the chip holder disclosed in Patent Document 2 has a chamfered portion so that the seating surface 13 and the side surfaces 14 and 15 are smoothly connected.

  Thus, as shown in Patent Documents 1 and 2, the notch groove or the chamfered portion is formed in the chip holder 2, so that stress is concentrated at the portion where the seating surface 13 and the side surfaces 14 and 15 intersect. This prevents the chip holder 2 from cracking.

Japanese Utility Model Publication No. 5-70820 JP 7-251302 A

  The end mill can perform grooving and stepping on the work material. When a small groove or a small diameter step is formed on the work material, a small diameter tip holder 2 is used. The small-diameter chip holder 2 has a smaller thickness dimension T1 in the circumferential direction R of the protrusion 17 than the large-diameter chip holder 2. Further, even when a plurality of, for example, three or more chips 3 are mounted on the chip holder 2, the thickness dimension T1 in the circumferential direction R of the convex portion 17 is reduced. In this case, even if a notch groove or a chamfered portion is formed as in each of Patent Documents 1 and 2 described above, the thickness T1 of the convex portion 17 itself cannot be increased, and the chip holder 2 There is a problem that cracks are likely to occur and the life of the chip holder 2 is shortened.

  Such a problem is a problem that particularly occurs in the small-diameter chip holder 2 and the chip holder 2 on which a large number of chips 3 are mounted. The same problem occurs when the reaction force applied to the chip holder 2 from the work material is large, such as when the speed is high.

Therefore, an object of the present invention is to provide a milling tool comprising a cutting insert and Chippuhoru da mounting it is possible to suppress the generation of cracks in the chip holder.

The present invention comprises a substantially cylindrical chip holder in which grooves that are recessed from the outer peripheral surface and the end surface of the tip end portion are formed ,
A rolling tool comprising a throw-away tip in which a part of the groove is housed and a main cutting edge protruding from an outer peripheral portion of the tip holder is formed,
The throw-away tip includes a top surface, a bottom surface facing the top surface, a first flank surface continuous with the top surface and the bottom surface, and a main portion formed at the intersection of the first flank surface and the top surface. A cutting edge and
The throw-away tip is in a state of being attached to the tip holder, than the holder circumferential dimension of the holder radially outer portion, it is formed shorter towards the holder circumferential dimension of the holder radially inner portion, wherein The tip holder has a seating surface with which the bottom surface of the throw-away tip comes into contact, and the seating surface intersects the seating surface and the first flank when viewed from the tip, and the tip holder It is located on the one side in the circumferential direction from the virtual straight line connecting the axis of
A height ratio value obtained by dividing the holder circumferential dimension of the holder radial inner part by the holder circumferential dimension of the holder radial outer part is 0.5 or more and 0.75 or less. It is a tool for turning .

Further, the present invention is characterized in that the throw-away tip is arranged such that the first flank surface intersects the seating surface of the tip holder substantially perpendicularly .

The present invention, the cutting insert, when mounted in the Chippuhoru da, characterized in that it has a minor cutting edge which protrudes from the tip end surface of the tip holder.

According to the present invention, the cutting tool having the throw-away tip mounted on the tip holder is formed with the main cutting edge protruding from the outer periphery of the tip holder by the throw-away tip. The cutting tool contacts the work material while rotating around the axis of the holder, so that the main cutting edge cuts the work material intermittently. As a result, the work material can be cut into a predetermined shape. When the main cutting edge comes into contact with the work material, the throw-away tip receives a reaction force corresponding to the cutting resistance from the work material and applies the reaction force to the chip holder.

When the throw-away tip is attached to the tip holder, the holder radial direction inner portion is formed to be shorter in the holder radial direction inner portion than the holder radial direction outer portion. Accordingly, in the tip holder to which the throw-away tip of the present invention is attached, the thickness of the inner portion in the holder radial direction is increased as much as the holder circumferential direction dimension of the inner portion in the holder radial direction is shortened in the throw-away tip. be able to.

As described above, according to the present invention, since the thickness of the radially inner portion of the chip holder can be increased, it is possible to prevent cracks from occurring in the radially inner portion of the chip holder. Thereby, the strength of the chip holder can be improved and the life of the chip holder can be extended. For example, by improving the strength of the tip holder, the tip holder can be prevented from being damaged and the workpiece can be cut even when the reaction force applied from the workpiece is large. As a result, the cutting amount can be increased or the cutting speed can be increased, and the working efficiency can be improved. Further, even when the tip holder has a small diameter or when a plurality of throw-away tips of 3 or more are attached to the tip holder, even if the thickness of the radially inner portion of the tip holder is potentially thin, By using the throw-away tip of the present invention, the strength reduction of the tip holder can be suppressed and the life of the tip holder can be extended.
Further, the height ratio value obtained by dividing the holder circumferential dimension of the inner part in the holder radial direction by the holder circumferential dimension of the outer part in the holder radial direction is selected to be 0.5 or more and 0.75 or less. If the height ratio value is too small, the strength of the throw-away tip will be insufficient. If the height ratio value is too large, the strength of the chip holder will be insufficient. According to the present invention, since the height ratio value is selected to be 0.5 or more and 0.75 or less, the strength of the tip holder can be improved while preventing the strength of the throw-away tip from being reduced. .

Furthermore , the cutting tool in which the throw-away tip is mounted on the tip holder has a main cutting edge and a sub cutting edge. That is, the cutting tool becomes an end mill. Thereby, grooving and stepping can be performed on the work material. According to the present invention, as described above, when the tip holder has a small diameter, or when a plurality of throwaway tips of three or more are mounted on the tip holder, the strength of the tip holder is potentially low. However, by using the throw-away tip of the present invention, the strength reduction of the tip holder can be suppressed and the life of the tip holder can be extended.

Further , almost the entire bottom surface formed on the throw-away tip comes into contact with the seating surface of the tip holder. Since the bottom surface of the chip and the seating surface of the holder are formed to be flat with each other, the chip holder can receive the reaction force applied from the work material through the throw-away chip over the entire seating surface. Therefore, according to the present invention, the chip holder can prevent the reaction force applied from the work material from concentrating on one point, and can prevent stress concentration and further improve the strength of the chip holder.

As described above, according to the present invention, by increasing the thickness of the radially inner portion of the tip holder to which the throw-away tip is mounted, it is possible to prevent cracks from occurring in the radially inner portion of the tip holder. In addition, the strength of the chip holder can be improved and the life of the chip holder can be extended. For example, by improving the strength of the chip holder, the cutting amount and the cutting speed can be increased, and the working efficiency can be improved. In addition, even when the tip holder has a small diameter or when a plurality of throwaway tips of 3 or more are mounted on the tip holder, even if the thickness of the radially inner portion of the tip holder is potentially low, The strength reduction of the chip holder can be suppressed, and the life of the chip holder can be extended.

Further , the above-mentioned throw-away tip is mounted on the tip holder to constitute a turning tool. Therefore, the tip holder can increase the thickness of the inner portion of the mounting portion in the radial direction of the holder by the amount that the holder circumferential direction of the inner portion in the radial direction of the holder of the throw-away tip is shortened. The strength of the holder can be improved, and the strength of the cutting tool can be improved accordingly. When the cutting edge of the cutting tool is worn or damaged, it is not necessary to replace the entire cutting tool by replacing the throw-away tip, and the cutting performance can be recovered.

  FIG. 1 is a front view showing a front end portion of an end mill 20 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the end mill 20 as seen from the S2-S2 cut line in FIG. The end mill 20 includes a throw-away tip 23 in which cutting edges 30 and 31 are formed and a tip holder 22 to which the tip 23 is detachably attached. In the present embodiment, the chip holder 22 is configured so that a large number, specifically, three throw-away chips 23 (hereinafter simply referred to as chips 23) can be mounted.

  The chip holder 22 is formed in a substantially cylindrical shape. A held portion (not shown) to be held by the milling machine is formed at the axial base end portion of the chip holder 22. In addition, a mounting portion 24 that holds the tip 23 in a state where the cutting edges 30 and 31 of the tip 23 protrude from the outer peripheral surface 32 and the end surface 33 is formed at the tip end portion in the axial direction of the tip holder 22. The end mill 20 is configured in a state where each chip 23 is mounted on the chip holder 22.

  The milling machine includes a movement drive unit that relatively moves and drives the clamped work material and the end mill 20 that holds the held portion of the chip holder 22, and a rotation drive unit that drives the held end mill 20 to rotate about the axis. including. The end mill 20 contacts the work material while rotating around the axis L <b> 1 of the chip holder 22, so that the cutting blades 30 and 31 formed by the chips 23 intermittently cut the work material. As a result, the work material can be cut into a predetermined shape. For example, the end mill 20 can be used to perform grooving and stepping on the work material. When the main cutting edge 30 or the auxiliary cutting edge 31 of the tip 23 is worn or broken, the end mill 20 can recover the cutting ability by replacing the tip 23.

  Hereinafter, the axis of the chip holder 22 is simply referred to as an axis L1. Further, the axial direction X along the axis L1 of the chip holder 22 and the direction going from the proximal end portion of the chip holder 22 to the distal end portion is referred to as one axial direction X1, and the direction from the distal end portion of the chip holder 22 toward the proximal end portion. Is referred to as the other axial direction X2. A direction toward the axis L1 along the radial direction Y of the chip holder 22 is referred to as a radial inner Y1, and a direction away from the axis L1 along the radial direction of the chip holder 22 is referred to as a radial outer Y2. In addition, the circumferential direction R around the axis L1 of the tip holder 22 and the direction in which the end mill 20 rotates is referred to as one circumferential direction R1, and the direction opposite to the rotational direction of the end mill 20 is referred to as the other circumferential direction R2.

A groove 27 is formed in the tip portion of the chip holder 22 so as to be recessed from the outer peripheral surface 32 and the tip end surface 33 of the chip holder 22. The groove 27 is a space that includes the throw-away chip accommodation space 26 and the chip accommodation space 25. The throw-away chip accommodating space 26 is a space in which almost the entire chip 23 is accommodated. The chip storage space 25 is a space for temporarily storing chips scraped by the chip 23. The throwaway chip accommodation space 26 and the chip accommodation space 25 are formed adjacent to each other. As shown in FIG. 2, in the groove 27, a region on the one circumferential side R <b> 1 side becomes the chip accommodating space 25, and a region on the other circumferential direction R <b> 2 side becomes the throw-away tip accommodating space 26. Further, in the present embodiment, the chip accommodating space 25 extends in the other axial direction X2 from the throw-away tip accommodating space 26 and is opened outward. The chips separated from the work material by the cutting blades 30 and 31 of the chip 23 are angularly displaced around the axis L <b> 1 in the state of being accommodated in the chip accommodating space 25 after being accommodated in the chip accommodating space 25. Escape from the opening of the chip accommodating space 25.

  The mounting portion 24 of the tip holder 22 serves as a throw-away tip accommodating space forming portion that defines the throw-away tip accommodating space 26. Specifically, the mounting portion 24 is erected in the circumferential direction one R1 with respect to the seating surface 40 adjacent to the seating surface 40 and the seating surface 40 which is the surface of the other circumferential direction R2 with respect to the groove 27. And two side surfaces 41, 42. The seating surface 40 is formed in a flat surface, is bent from the end surface 33 of the chip holder 22 and extends in the other axial direction X2, and is bent from the outer peripheral surface 32 of the chip holder 22 and extends inward in the radial direction Y1.

  The first side surface 41, which is one of the two side surfaces 41, 42, is adjacent to the edge of the seating surface 40 on the radially inner side Y <b> 1 side, and is erected in the circumferential direction one R <b> 1 with respect to the seating surface 40. The second side surface 42, which is the other of the two side surfaces 41, 42, is adjacent to the edge of the seating surface 40 in the axial direction on the other side X <b> 2 and is erected on the seating surface 40 in one circumferential direction R <b> 1. In addition, the mounting portion 24 is formed with a screw hole that immerses from the seating surface 40 in the other circumferential direction R2. The screw hole is formed with an inner screw and becomes a recess for fixing the chip 23.

  The chip holder 22 has a chip storage space forming part that defines the chip storage space 25. Specifically, the chip accommodating space forming portion is adjacent to the first side surface 41, extends in one circumferential direction R <b> 1, and continues to the outer peripheral surface 32 of the chip holder 22, and the second side surface 42. A second wall surface 45 adjacent to the second side surface 42 extends in the other axial direction X2 and a second wall surface 45 adjacent to the second wall surface 45 extends from the second wall surface 45 in the circumferential direction one R1 and continues to the outer peripheral surface 32 of the chip holder 22. 3 wall surfaces 44. A region surrounded by the seating surface 40, the side surfaces 41, 42, and the wall surfaces 43, 44, 45 is a groove 27. The groove 27 is substantially fan-shaped in cross section perpendicular to the axis L1, and has a substantially uniform space along the axis L1.

  As described above, a plurality of recesses are formed in the tip portion of the chip holder 22 at intervals in the circumferential direction R by the grooves 27. The groove 27 is a recess, and a portion between two recesses adjacent in the circumferential direction R is a protrusion 46. A plurality of convex portions 46 project radially outward Y2 from the radially inner portion 47, and are formed at intervals in the circumferential direction R, and the mounting portion 24 is formed on each convex portion 46, respectively. That is, each chip 23 is attached to each convex portion 46.

  Of the two grooves 27 adjacent to each other in the circumferential direction R, the seating surface 40 of the groove 27 in one circumferential direction R1 and the first wall surface 43 of the groove 27 in the other circumferential direction R2 are circumferentially extended toward the outer side in the radial direction Y2. Extends away from direction R. As a result, the convex portion 46 is formed such that the circumferential dimension S2 of the radially outer portion is larger than the circumferential dimension S1 of the radially inner portion 47, and the radial dimension increases toward the radially outward Y2. .

FIG. 3 is a perspective view showing the chip 23. FIG. 4 is a plan view showing the chip 23. FIG. 5 is a front view showing the chip 23. FIG. 6 is a right side view showing the chip 23. The chip 23 is generally formed in a plate-like rectangular parallelepiped shape, and the surface in the thickness direction is formed in a rectangular shape. Of the directions perpendicular to the thickness directions A1 and A2 of the chip 23, directions extending along the long sides of the surface in the thickness direction are referred to as longitudinal directions B1 and B2. Of the directions perpendicular to the thickness direction A1, A2 of the chip 23, the direction extending along the short side of the surface in the thickness direction is referred to as the width direction C1, C2.

  As for the chip | tip 23, the cutting blades 30 and 31 are formed in the edge of the surface of one thickness direction A1. Specifically, in the tip 23, the main cutting edge 30 is formed on one first long side portion 60 of the pair of opposed long side portions 60 and 61. The tip 23 is formed with the auxiliary cutting edge 31 on the first short side portion 62 of the pair of opposing short side portions 62 and 63. Hereinafter, in the width direction C, the direction from the second long side portion 61 to the first long side portion 60 is referred to as the width direction C1, and the direction from the first long side portion 60 to the second long side portion 61 is the width direction. On the other hand, C2. Further, in the longitudinal direction B, the direction proceeding from the second short side portion 63 to the first short side portion 62 is defined as one longitudinal direction B1, and the direction proceeding from the first short side portion 62 to the second short side portion 63 is defined as the other longitudinal direction. Let B2.

  The chip 23 is formed with a through-hole 50 that is inserted in the thickness direction A from the center of one surface in the thickness direction A1. The through hole 50 is a hole for fixing the chip 23 to the chip holder 22. The through-hole 50 is formed with an internal thread.

  In addition, the chip 23 of the present embodiment has a cross-sectional shape cut along a cutting plane perpendicular to the longitudinal direction B, which is formed substantially uniformly in the longitudinal direction B. Further, a cross-sectional shape cut by a cutting plane perpendicular to the width direction C is formed non-uniformly in the width direction C. Specifically, as shown in FIG. 6, the dimension in the thickness direction decreases from the first long side portion 60 where the main cutting edge 30 is formed toward the second long side portion 61 along the width direction C. . That is, the thickness direction dimension S3 of the first long side portion 60 is formed larger than the thickness direction dimension S4 of the second long side portion 61. Accordingly, the bottom surface 39 serving as the surface of the other side A2 in the thickness direction approaches the upper surface 54 serving as the surface of the one side A1 in the thickness direction as it proceeds to the other side C2. Here, the thickness direction dimension of the chip 23 is the thickness direction in the projected shape of the chip 23 when the chip 23 is projected onto a virtual plane perpendicular to the longitudinal direction.

  Further, the upper surface of the first long side portion 60 where the main cutting edge 30 is formed is inclined to the other in the thickness direction as it proceeds from the main cutting edge 30 to the other width direction C2. Moreover, the sub cutting edge 31 inclines to thickness direction other A2 as it goes to width direction other C2. Further, the surface of the one side C1 in the width direction of the chip 23 becomes a first flank 55 that proceeds in the other side C2 in the width direction as it proceeds in the other side A2. In addition, the surface of the tip 23 in the longitudinal direction one C1 becomes a second flank 56 that proceeds in the other longitudinal direction B2 as it proceeds in the other thickness direction A2. In the present embodiment, the first flank 55 and the bottom surface 39 form a substantially vertical angle.

  Further, the surface of the other side C <b> 2 in the width direction of the chip 23 becomes a first contact surface 51 that contacts the first side surface 41 of the chip holder 22. The surface of the other side B <b> 2 in the longitudinal direction of the chip 23 becomes a second contact surface 52 that contacts the second side surface 42 of the chip holder 22. Further, the surface that becomes the other side A <b> 2 in the thickness direction is a bottom surface 39 that comes into contact with the seating surface 40 of the chip holder 22. The contact surfaces 51 and 52 and the bottom surface 39 are formed in a substantially flat surface, and contact the side surfaces 41 and 42 and the seating surface 40 of the chip holder 22 over the entire surface.

  The through holes 50 formed in the chip 23 and the mounting portion 24 in a state where the contact surfaces 51 and 52 and the bottom surface 39 of the chip 23 are in contact with the side surfaces 41 and 42 and the seating surface 40 of the chip holder 22, respectively. The screw hole formed in the shaft is coaxial. In this state, by screwing the screw member on which the external screw is formed into the through hole 50 and the screw hole of the chip 23, the chip 23 can be fastened to the mounting portion 24 of the chip holder 22, and the chip 23 is fixed to the chip 23. It can be mounted on the mounting portion 24 of the holder 22. The chip 23 attached to the chip holder 22 has a substantially longitudinal direction B extending along the axial direction X of the chip holder 22, and a width direction C extending substantially along the radial direction Y of the chip holder 22. In particular, the thickness direction A extends along the circumferential direction R of the chip holder 22.

  FIG. 7 is a cross-sectional view showing a state in which the chip 23 of this embodiment is mounted on the chip holder 22. In a state where the tip 23 is mounted on the mounting portion 24, the tip 23 is mostly accommodated in the groove 27, and the main cutting edge 30 protrudes in a radially outward direction Y <b> 2 from the outer peripheral surface 32 of the tip holder 22. The auxiliary cutting edge 31 protrudes from the tip surface 33 of the chip holder 22 in one axial direction X1 with a predetermined protrusion amount U2. Further, when the tip 23 is mounted on the mounting portion 24, the holder circumferential dimension S6 of the holder radial inner portion 47 is formed shorter than the holder circumferential dimension S5 of the holder radial outer portion. Here, the holder circumferential dimension of the chip 23 is the holder circumferential dimension in the projected shape of the chip 23 when the chip 23 is projected onto a virtual plane perpendicular to the holder axis L1.

On the other hand, if the holder circumferential dimension S6 of the inner portion in the holder radial direction is too short, the reaction force F received from the work material may cause the tip 23 to be detached from the mounting portion 24 or to be displaced from a predetermined position. In the present embodiment, the holder circumferential direction dimension S5 of the tip 23 in the holder radial direction outward direction is the holder circumferential direction in which the tip 23 can be securely attached to the attachment portion 24 even when receiving the reaction force F from the work material. The dimension is set to S5 and is set to be as small as possible. Specifically, the height ratio value (S6 / S 5 ) obtained by dividing the circumferential dimension S6 of the inner part in the holder radial direction by the circumferential dimension S5 of the outer part in the holder radial direction is 0.5 or more and 0 .75 or less is selected.

FIG. 8 is a cross-sectional view showing a state in which the chip 123 of the comparative example is mounted on the chip holder 122 of the comparative example. About the structure of a comparative example, the structure corresponding to a present Example attaches | subjects the reference code which added 100 to the reference code of a present Example. The outer shapes of the end mills of the present embodiment and the comparative example are equal, that is, the shape of the cutting blade and the chip accommodating space are formed equally. In the comparative example, the chip 123, the thickness dimension of the first long side portion 160 of the main cutting edge 1 30 is formed, the thickness dimension of the second long side portion 161 is set equal. That is, in the state in which the chip 123 is mounted on the mounting portion 124, the holder circumferential dimension S7 of the outer portion in the holder radial direction and the holder circumferential dimension S8 of the inner portion in the holder radial direction are formed to be equal.

  In the present embodiment, the chip 23 is formed so that the holder radial direction inner portion 61 is shorter in the holder circumferential direction than the holder radial direction outer portion 60 in a state where the chip 23 is mounted on the mounting portion 24 of the chip holder 22. Is done. Therefore, the tip holder 22 increases the thickness T2 of the inner portion in the holder radial direction of the convex portion 46 by the amount that the holder circumferential direction dimension S6 of the inner portion 61 in the radial direction of the holder of the tip 23 is formed shorter. Can do. On the other hand, in the comparative example, the holder circumferential direction dimension S8 of the inner portion 161 in the holder radial direction is formed larger than that of the present embodiment, and therefore, the convex portion 146 is compared with the tip holder 22 of the present embodiment. The thickness T1 of the inner part in the holder radial direction is reduced.

  Therefore, since the outer shape of the end mill 20 of this embodiment is equal to the outer shape of the end mill 120 of the comparative example, the cutting performance can be made the same as that of the comparative example. Further, according to the present embodiment, since the thickness T2 of the radially inner portion of the chip holder 22 to which the chip 23 is mounted can be increased, the radially inner portion of the chip holder 22 is compared with the comparative example. It is possible to prevent cracks from occurring. Therefore, the strength of the chip holder 22 can be improved and the life of the chip holder 22 can be extended. For example, by improving the strength of the chip holder 22, the cutting amount and the cutting speed can be increased, and the working efficiency can be improved. Further, even when the strength of the chip holder 22 is potentially low, such as when the diameter of the chip holder 22 is small or when three or more chips 23 are mounted on the chip holder 22, By using the chip 23, the strength reduction of the chip holder 22 can be suppressed, and the life of the chip holder 22 can be extended. For example, when the tip holder 22 has a diameter of 32 mm or less, the effect of using the tip 23 of the present embodiment is great.

  In the present embodiment, the convex portion 46 of the chip holder 22 is formed such that the circumferential dimension S2 of the radially outer portion is larger than the circumferential dimension S1 of the radially inner portion, and the radially outward Y2 As it goes, the radial dimension increases. Therefore, the radial inner portion is thinner and the radial inner portion is lower in strength. In the present embodiment, as described above, the thickness of the radially inner portion of the convex portion 46 of the chip holder 22 can be increased as much as possible, and the strength of the chip holder 22 can be effectively improved. In other words, it is possible to prevent the chip holder 22 from cracking by extending the seating surface 40 away from the thinnest portion of the convex portion 46.

  In addition, according to the present embodiment, the main cutting edge 30 and the auxiliary cutting edge 31 are formed on the tip 23, so that the cutting tool with the tip 23 mounted on the tip holder 22 can be used as the end mill 20. . Thereby, grooving and stepping can be performed on the work material. Further, the end mill 20 may be formed with a smaller diameter than the remaining rolling tool. As described above, in the present embodiment, even when the end mill 20 is formed with a small diameter, a decrease in strength of the chip holder 22 can be suppressed, and the life of the chip holder 22 can be extended.

  Further, according to the present embodiment, almost the entire bottom surface 39 formed on the chip 23 abuts on the seating surface 40 formed on the mounting portion 24 of the chip holder 22. Since the bottom surface 39 and the seating surface 40 are formed to be flat with each other, the chip holder 22 can receive the reaction force F applied from the work material via the chip 23 in a distributed manner across the seating surface 40. Thereby, the chip holder 22 can prevent the reaction force F applied from the work material from concentrating on one point, and can prevent the stress concentration and further improve the strength of the chip holder 22.

  In the present embodiment, in this embodiment, the height ratio value (S6 / S5) obtained by dividing the circumferential dimension S6 of the holder radial direction inner part by the circumferential dimension S5 of the holder radial direction outer part is: It is selected to be 0.5 or more and 0.75 or less. For example, if the height ratio value is too small, the strength of the chip 23 is insufficient. If the height ratio value is too large, the strength of the chip holder 22 will be insufficient. In the present embodiment, the height ratio value is selected to be 0.5 or more and 0.75 or less, so that the strength of the chip holder 22 can be improved while preventing the strength of the chip 23 from being lowered. .

  Further, in the present embodiment, when considering the virtual straight line 70 that connects the intersection 71 that intersects the seating surface 40 and the first flank 55 and the axis L1 of the chip holder, the seating surface 40 is more circumferential than the virtual straight line 70. Located in one direction R1. As a result, when the reaction force F is received from the work material, stress can be prevented from concentrating on the portion 72 where the first side surface 41 and the seating surface 40 intersect. In addition, the position where the seating surface 40 and the first contact surface 51 intersect with each other is arranged in the radially inner Y1 as compared with the comparative example, and arranged in one circumferential direction R1, thereby further increasing the strength of the chip holder 22. Can be improved. In the present embodiment, the first flank 55 and the bottom surface 39 form an approximately vertical angle. As a result, the first flank 55 and the main cutting edge 30 can be accurately formed by polishing or the like.

  Moreover, in this Embodiment, the main cutting edge 30 is formed in the 1st long side part 60 used as one of the two long side parts 60 and 61, and the sub-cutting edge 31 is out of the two short side parts 62 and 63. It forms in the 1st short side part 62 used as one side. Therefore, it is not necessary to form a cutting edge in the second long side portion 61 and the second short side portion 63, and the shape restriction of the chip 23 can be reduced.

The present embodiment as described above is merely an example of the invention, and the configuration can be changed within the scope of the invention. For example, although an end mill has been described as a turning tool, the same effect can be obtained even with other turning tools such as a milling turning tool. Further, in the state where the chip 23 is mounted on the chip holder 22, it is only necessary that the holder radial direction inner portion is formed to have a shorter holder circumferential dimension than the holder radial direction outer portion. Other shapes are not limited. For example, a positive axial rake or a negative radial rake may be selected for the chip 23. In this case, the cross-sectional shape cut by the cutting plane perpendicular to the longitudinal direction B of the chip 23 is formed non-uniformly in the longitudinal direction B. Such a case is also included in the present invention. Also, the shapes of the throw-away tip accommodating space 26 and the chip accommodating space 25 may be formed other than the shapes described above.

It is a front view which shows the front-end | tip part of the end mill which is one Embodiment of this invention. It is sectional drawing of the end mill seen from the S2-S2 cut surface line of FIG. It is a perspective view which shows the chip | tip which is one Embodiment of this invention. It is a top view which shows the chip | tip which is one Embodiment of this invention. It is a front view which shows the chip | tip which is one Embodiment of this invention. It is a right view which shows the chip | tip which is one Embodiment of this invention. It is sectional drawing which shows the state with which the chip | tip of a present Example was mounted | worn with the chip | tip holder of a present Example. It is sectional drawing which shows the state with which the chip | tip of the comparative example was mounted | worn with the chip | tip holder of the comparative example. It is a top view which shows the throw away end mill of a prior art. It is sectional drawing of the throwaway end mill seen from the S10-S10 cutting plane line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 End mill 22 Tip holder 23 Throw away tip 24 Mounting part 27 Groove 30 Main cutting edge 31 Sub cutting edge 32 Outer peripheral surface 33 End surface 39 Bottom surface 40 Seating surface

Claims (3)

A substantially cylindrical chip holder in which a groove is formed to be recessed from the outer peripheral surface and the end surface of the tip , and
A rolling tool comprising a throw-away tip in which a part of the groove is housed and a main cutting edge protruding from an outer peripheral portion of the tip holder is formed,
The throw-away tip includes a top surface, a bottom surface facing the top surface, a first flank surface continuous with the top surface and the bottom surface, and a main portion formed at the intersection of the first flank surface and the top surface. A cutting edge and
The throw-away tip is formed in a state in which the holder circumferential dimension of the inner portion in the holder radial direction is shorter than the holder circumferential size of the outer portion in the radial direction of the holder in a state of being mounted on the tip holder ,
The tip holder has a seating surface with which the bottom surface of the throw-away tip contacts, and the seating surface intersects the seating surface and the first flank in a tip view, and the tip Located on one side in the circumferential direction from the virtual straight line connecting the axis of the holder,
A height ratio value obtained by dividing the holder circumferential dimension of the holder radial inner part by the holder circumferential dimension of the holder radial outer part is 0.5 or more and 0.75 or less. Tool for turning. 2. The rolling tool according to claim 1, wherein the throw-away tip is arranged such that the first flank face intersects the seating surface of the tip holder substantially perpendicularly. The throw-away tip, said in a state of being attached to Chippuhoru da, the milling tool of claim 1, wherein in that it has a minor cutting edge which protrudes from the tip end surface of the tip holder .

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