JP2019104102A - Tip exchangeable type boring tool - Google Patents

Abstract

To provide a tip exchangeable type boring tool which can prevent, in advance, fitting of a cutting insert in a wrong attitude, and does not reduce chip discharge performance.SOLUTION: A tip exchangeable type boring tool 1 comprises a cutting insert 2, and a body 3. The body 3 is cylindrical, a chip discharge groove 4 is formed on an outer periphery of the body, and a chip seat 6, on which the cutting insert 2 can be loaded, is formed at a tip of the body. A groove wall 42, which is directed in a direction opposite to a rotation direction T of the body 3, of wall grooves 41, 42 which constitute the chip discharge groove 4 has, at a tip thereof, an overhung part 7 which projects so as to cover a part of a top face 10 of the cutting insert 2. A maximum value of a size of a gap b between the overhung part 7 and the top face 10 of the cutting insert 2 is smaller than a height a of a restraint wall 61 which constitutes the chip seat 6.SELECTED DRAWING: Figure 7

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indexable drilling tool, and more particularly to an indexable drilling tool for making a small diameter and deep hole.

  When manufacturing a relatively small diameter gun drill, the size of the cutting insert and the tip seat where it is installed inevitably become smaller. The smaller tip seat also lowers the height of the restraining wall (the wall in contact with the cutting insert) around the tip seat. When the restraining wall is lowered, the end of the cutting insert may float up in the process of screwing the cutting insert, and even if the end of the cutting insert rides on the restraining wall, it may not notice that the cutting insert has climbed due to the low restraining wall. . Cutting in this state causes breakage of the cutting insert and body.

  Therefore, in the case of small diameter, methods other than screwing are required. Patent document 1 is one of the countermeasure, and discloses one of the deep hole tools which can exchange a cutting edge. In the deep hole tool of Patent Document 1, a cutter plate (also referred to as a "cutting insert") having a cutting edge is pressed and fixed by a clamping claw from the rake surface side.

Japanese Patent Application Laid-Open No. 51-97880

In the case of the method of fixing the cutting insert as in Patent Document 1, since the clamping claw is a separate body, it is necessary to hold down a large portion of the rake surface in order to securely fix the cutting insert. Therefore, the clamping claws become large, and the space for the chip discharge groove is occupied largely. As a result, chip discharge performance is reduced.
An object of this invention is to provide the blade-tip-exchange-type drilling tool which can prevent that a cutting insert is attached by an incorrect attitude | position in view of said subject. Another object of the present invention is to provide an indexable drilling tool which does not reduce chip dischargeability.

  An indexable drilling tool according to an aspect of the present invention includes a cutting insert and a body, and the tip of one groove wall of a chip discharge groove formed on the outer periphery of the body has one of the upper surfaces of the cutting insert. An overhanging portion projecting in the outer peripheral direction of the body is formed so as to cover the portion, and the maximum value of the gap between the overhanging portion and the upper surface of the cutting insert is smaller than the height of the wall constituting the tip seat.

In the above aspect, the tool diameter may be 15 mm or less.
When the diameter of the drilling tool is set to 15 mm or less, the size of the cutting insert and the tip seat for installing it become smaller. The smaller tip seat also lowers the height of the restraining wall around the tip seat. If you try to place the cutting insert from the direction perpendicular to the bottom of the tip seat, the restraining wall of the tip seat and the bottom of the cutting insert make contact, and the cutting insert is attached in an inclined state to the bottom of the tip seat There is a risk of
However, in this aspect, since the projecting portion is formed, the cutting insert can not be placed from the direction perpendicular to the bottom surface of the tip seat, so that the cutting insert can be prevented from being attached in an incorrect posture.

In the above aspect, it is preferable that a plurality of step portions be formed on the cutting edge when the cutting insert is viewed from the direction facing the upper surface.
According to this aspect, since narrow chips can flow out of the cutting edge divided at the step portion, the chips can be subdivided.

In the above aspect, L / D may be 10 or more. However, L mentioned above represents the length of a chip discharge groove, and D represents a tool diameter.
When manufacturing a small diameter gun drill having a L / D of 10 or more, the size of the cutting insert and the tip seat for installing it become smaller. The smaller tip seat also lowers the height of the restraining wall around the tip seat. When the restraining wall is lowered, the end of the insert may float up in the process of screwing the insert, and even if the end of the insert rides on the restraining wall, it may not notice that the insert has climbed up because the restraining wall is low. Cutting in this state causes breakage of the insert and body.
However, in this aspect, since the overhanging portion is formed, the cutting insert can be attached in an incorrect posture even with an indexable drilling tool having a small diameter and a deep hole with L / D of 10 or more. You can prevent things in advance.

  ADVANTAGE OF THE INVENTION According to this invention, the blade-tip-exchange-type drilling tool which can prevent beforehand that a cutting insert is attached in a wrong attitude | position can be provided. Furthermore, it is possible to provide an indexable drilling tool which can be securely fixed even with a small diameter cutting insert and can minimize the reduction in chip discharge performance.

FIG. 1 is a front view of a drilling tool according to an embodiment of the present invention. FIG. 2 is an enlarged perspective view showing a tip portion of a drilling tool according to an embodiment of the present invention. FIG. 3 is an enlarged front view of a drilling tool according to an embodiment of the present invention. FIG. 4 is an enlarged plan view of a drilling tool according to an embodiment of the present invention. FIG. 5 is a rear view showing the drilling tool according to the embodiment of the present invention in an enlarged manner. FIG. 6 is a view of a drilling tool according to an embodiment of the present invention as viewed from the tip side. 7 is a cross-sectional view taken along the line VII-VII in FIG. FIG. 8 is a perspective view of a cutting insert according to an embodiment of the present invention. FIG. 9 is a front view of a cutting insert according to an embodiment of the present invention. FIG. 10 is a left side view of a cutting insert according to an embodiment of the present invention. 11 is a cross-sectional view taken along the line XI-XI in FIG.

  Hereinafter, an embodiment of the present invention will be described using the drawings. In addition, what attached the same code | symbol in each figure has the same or same structure. One of the features of the drilling tool 1 according to each embodiment of the present invention is that the overhanging portion 7 is formed on the groove wall 42 of the chip discharge groove 4 (see FIG. 2). The overhanging portion 7 is formed as an integral structure with the groove wall 42 (see FIG. 7), and covers a part of the upper surface 10 of the cutting insert 2 in a plan view (see FIG. 3). The overhanging portion 7 can be formed smaller than the externally attached clamping claw, and therefore does not occupy a large space of the chip discharge groove 4. It is possible to minimize the drop in chip dischargeability of the drilling tool 1.

  The maximum value of the size of the gap b between the projecting portion 7 and the cutting insert 2 is set smaller than the height a of the wall constituting the tip seat 6 (see FIG. 7). This can prevent the cutting insert 2 from being attached in the wrong posture. Since each cutting edge 11 is divided into partial cutting edges 11 a and 11 b with the step portion 12 as a boundary (see FIG. 9), the chips flowing out of the cutting edge 11 can be subdivided.

  The contact surface 14 of the cutting insert 2 is not flush with the cutting edge 11, and is retracted to the center O side of the cutting insert 2 more than the cutting edge 11 (see FIG. 11). Even if the cutting edge 11 is divided by the stepped portion 12, the contact surface 14 which is not divided into the stepped portion 12 can be formed (see FIGS. 8 and 10). Can be secured. Hereinafter, each configuration will be described in detail with reference to FIGS. 1 to 11.

  FIG. 1 is a front view showing a drilling tool 1 according to an embodiment of the present invention. As shown in FIG. 1, the drilling tool 1 according to the present embodiment includes a cutting insert 2 and a body 3 to which the cutting insert 2 is attached. The drilling tool 1 rotates in the direction of the arrow T to cut a deep hole in a workpiece. In the illustrated example, the tool diameter D of the drilling tool 1 is set to 15 mm.

  FIG. 2 is an enlarged perspective view of the tip of the drilling tool 1. As shown in FIG. 2, the body 3 is formed in a substantially cylindrical shape. In the outer peripheral portion of the body 3, a chip discharge groove 4 is formed linearly along the central axis of the body 3. The chip discharge groove 4 is composed of a groove wall (wall surface) 41 and a groove wall (wall surface) 42, and has a substantially V-shaped cross section. Assuming that the length of the chip discharge groove 4 is L, the L / D of the drilling tool 1 is set to, for example, L / D = 10 or more.

  FIG. 3 is a front view showing the drilling tool 1 in an enlarged manner. At the tip of the drilling tool 1, the groove wall 42 has an overhang 7 that protrudes to cover a part of the top surface 10 of the cutting insert 2 in a front view. The overhanging portion 7 will be described in detail later with reference to FIGS. 6 and 7.

  FIG. 4 is a plan view showing the guide pad 51, and FIG. 5 is a rear view showing the guide pad 52. As shown in FIG. As shown in FIGS. 4 and 5, two guide pads 51 and 52 are fixed to the body 3 by screws on the outer periphery of the tip of the body 3. Since the guide pads 51 and 52 are configured to be replaceable, it is possible to omit the time-consuming re-polishing of the guide pad. The guide pads 51, 52 are arranged to support the cutting force of the cutting edge 11, prevent breakage of the drilling tool 1 caused by bending, and improve the roundness, straightness and surface roughness of the deep hole. Let

  6 is a view of the drilling tool 1 viewed from the tip side, and FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. As shown in FIGS. 6 and 7, the tip seat 6 for mounting the cutting insert 2 is a groove wall of the chip discharge groove 4 at the tip of the groove wall 41 (see FIG. 2) of the chip discharge groove 4. It is recessed more than 41 and formed. Therefore, the position of the upper surface 10 of the cutting insert 2 attached to the tip seat 6 is approximately the same height as the groove wall 41 of the chip discharge groove 4. Out of the groove walls 41 and 42 of the chip discharge groove 4, the projecting portion 7 is integrally formed with the groove wall 42 at the tip of the groove wall 42 facing in the direction opposite to the rotational direction T.

  The overhanging portion 7 is formed to protrude in the outer peripheral direction of the body 3, and a gap b is formed between the overhanging portion 7 and the cutting insert 2. Further, when the drilling tool 1 is viewed from the direction opposite to the upper surface 10 of the cutting insert 2, the overhanging portion 7 covers a part of the upper surface 10 of the cutting insert 2. That is, as shown in the cross-sectional view of FIG. 6, the overhanging portion 7 is disposed above the upper surface 10 of the cutting insert 2. The drilling tool 1 of the present embodiment has an overhanging portion 7 for restricting the movement of the cutting insert 2 in the lifting direction in addition to the screw for pressing the inner peripheral surface of the screw hole 8 of the cutting insert 2. Even the cutting insert 2 of the above can be fixed securely.

  In addition, the maximum value of the size of the gap b between the overhang 7 and the cutting insert 2 is set smaller than the height a of the wall constituting the tip seat 6. Strictly speaking, the maximum value of the clearance b is smaller than the height a of the portion 61 of the tip seat 6 which abuts on the cutting insert 2 (hereinafter this portion is referred to as "restraint wall"). It is set. In addition, depending on the side shape of the cutting insert 2, the height a of the restraint wall 6 may differ depending on the part. In that case, the maximum value of the gap b between the overhang 7 and the cutting insert 2 is set based on the lower height a.

  Assuming that the cutting insert 2 can be placed from a direction perpendicular to the bottom surface of the tip seat 6 if it is a drilling tool without the overhanging portion 7, the restraining wall 61 of the tip seat 6 and the bottom surface of the cutting insert 2 There is a risk that the cutting insert 2 may come into contact with the bottom surface of the tip seat 6 while being inclined. On the other hand, in the drilling tool 1 of the present embodiment shown in FIG. 7, the overhanging portion 7 is formed so that the maximum value of the gap b is smaller than the height a of the restraint wall 61. The cutting insert can not be placed from the direction perpendicular to the bottom surface of the seat 6. It is possible to prevent in advance that the cutting insert 2 is attached in an incorrect posture.

  FIG. 8 is a perspective view of the cutting insert 2 according to an embodiment of the present invention. As shown in FIG. 8, the cutting insert 2 has an upper surface 10 to be a rake surface, a lower surface 9 opposite to the upper surface 10, and a side surface 13 connecting the upper surface 10 and the lower surface 9. At the center O of the cutting insert 2, a screw hole 8 penetrating the upper surface 10 and the lower surface 9 is formed.

  A cutting edge 11 is formed on a ridge line R where the upper surface 10 and the side surface 13 intersect. In the illustrated example, a pair of cutting edges 11 is formed on one side of the ridge line R and on the other side opposite to the one side. In addition, the number of the cutting edges 11 formed in the ridgeline R is not limited, One may be sufficient and three or more may be sufficient. The pair of cutting edges 11 is formed point-symmetrically with respect to the center O of the cutting insert 2. The side surface 13 includes a pair of portions 15 connected to each cutting edge 11, and a pair of abutment surfaces 14 adjacent to each portion 15. The portion 15 and the abutment surface 14 will be described in more detail below with reference to FIGS. 10 and 11.

  FIG. 9 is a front view of the cutting insert 2. As shown in FIG. 9, when the cutting insert 2 is viewed from the direction opposite to the upper surface 10 thereof, the cutting edges 11 formed on the cutting insert 2 each have a step portion 12. That is, when the position of the partial cutting edge 11a positioned on the left side of the drawing with respect to the step portion 12 is compared with the position of the partial cutting edge 11b positioned on the right side of the step portion 12, the partial cutting edge 11b cuts It is in a position where it is retracted toward the center O side of the insert 2. The cutting edge 11 is divided into the partial cutting edges 11 a and 11 b by having the step portion 12, and the chips flowing out of the cutting edge 11 are divided and subdivided.

  FIG. 10 is a left side view of the cutting insert 2, and FIG. 11 is a cross-sectional view taken along the line XI-XI in FIG. As shown in FIGS. 10 and 11, the side surface 13 of the cutting insert 2 is formed with an abutting surface 14 that abuts on a wall that constitutes the tip seat 6. The contact surface 14 is formed at a position relatively closer to the lower surface 9 than the portion 15 of the side surface 13 connected to the cutting edge 11. Further, as shown in the cross-sectional view of FIG. 10, the contact surface 14 is at a position retracted to the center O side of the cutting insert 2 more than the cutting edge 11. In other words, the contact surface 14 is formed on the lower side of the portion 15 in the height direction along the central axis of the cutting insert 2 and on the center O side of the portion 15 in the radial direction radially extending from the center O It's recessed.

  Next, the effects of the above embodiment will be described. By forming the projecting portion 7 integrally with the groove wall 42 of the chip discharge groove 4, it is sufficient even if the area covering the upper surface 10 of the cutting insert 2 is smaller than in the prior art. As a result, cutting of the chip discharge groove 4 A large area can be secured.

  Even when the tool diameter D of the drilling tool 1 is set to, for example, 15 mm or less, the formation of the overhanging portion 7 can prevent the cutting insert 2 from being attached in an incorrect posture. That is, when the tool diameter D of the drilling tool 1 is set to 15 mm or less, it is difficult to reduce the size of the cutting insert 2 along with the reduction of the tool diameter. When the cutting insert 2 is to be placed, the restraining wall 61 of the tip seat 6 and the bottom surface of the cutting insert 2 make contact, and there is a risk that the cutting insert 2 may be attached in an inclined state with respect to the bottom face of the tip seat 6 is there.

  On the other hand, according to the present embodiment in which the overhanging portion 7 is formed, the cutting insert 2 can not be placed from the direction perpendicular to the bottom surface of the tip seat 6, and the cutting insert 2 is against the bottom surface of the tip seat 6. It can only be placed from the parallel direction. Therefore, it is prevented in advance that the cutting insert 2 gets stuck to the tip seat 6 in the inclined posture.

  The embodiments described above are for the purpose of facilitating the understanding of the present invention, and are not for the purpose of limiting the present invention. The elements included in the embodiment and the arrangement, the material, the conditions, the shape, the size, and the like of the elements are not limited to those illustrated, and can be changed as appropriate. In addition, configurations shown in different embodiments can be partially substituted or combined with each other.

  DESCRIPTION OF SYMBOLS 1 ... drilling tool, 2 ... cutting insert, 3 ... body, 4 ... chip discharge groove, 6 ... tip seat, 7 ... overhang part, 8 ... screw hole, 9 ... lower surface, 10 ... upper surface, 11 ... cutting edge, 11a , 11b: partial cutting edge, 12: step portion, 13: side surface, 14: contact surface, 15: part of side surface, 41, 42: groove wall (wall surface), 51, 52: guide pad, 61: restraint wall , A: height of restraint wall, b: gap between overhanging portion and cutting insert, D: tool diameter, L: length of chip discharge groove, O: center, R: ridge line, T: direction of rotation.

Claims (5)

A cutting insert,
A body having a cylindrical shape, a chip discharge groove formed on the outer periphery, and a tip seat on which the cutting insert can be mounted at the tip end portion;
An indexable drilling tool comprising:
Among the wall surfaces constituting the chip discharge groove, the wall surface facing in the direction opposite to the rotational direction of the body has an overhanging portion projecting at a tip end thereof so as to cover a part of the upper surface of the cutting insert,
The blade-tip-exchange-type drilling tool, wherein the maximum value of the size of the gap between the overhanging portion and the upper surface of the cutting insert is smaller than the height of the wall constituting the tip seat.   The indexable drill bit according to claim 1, wherein the tool diameter is 15 mm or less.   The blade according to claim 1 or 2, wherein the cutting edge has a plurality of steps when the cutting insert is viewed from the direction opposite to the upper surface thereof.   The indexable drilling tool according to any one of claims 1 to 3, wherein L / D is 10 or more (wherein L: length of chip discharge groove D: tool diameter). The side surface of the cutting insert has an abutment surface that abuts a wall that constitutes the tip seat,
The said contact surface is a recessed part to the center side of the said cutting insert rather than the said cutting edge, when it sees in a cross section perpendicular | vertical to the cutting edge of the said cutting insert, Indexable drilling tool.

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