JP4055153B2 - Throw-away drill - Google Patents

Description

  In the present invention, a throw-away tip (hereinafter referred to as a tip) having a substantially flat tip body with a cutting edge formed at the tip is attached to and detached from a recessed groove-like tip mounting seat formed at the tip of the drill body. The present invention relates to a throw-away drill that can be mounted.

  As an example of this type of throw-away drill, for example, as disclosed in Patent Document 1, a round hole is formed on the bottom surface of a groove-shaped tip mounting seat that opens at the tip surface of the drill body. A shaft portion that can be inserted into the round hole is provided on the rear end surface of the substantially flat chip that is fixedly mounted on the mounting seat, and the shaft portion is inserted into the round hole and formed on the shaft portion. There is a type in which a chip is fixedly mounted on a chip mounting seat by engaging an engaging member that protrudes and protrudes from the inner periphery of a round hole into the cutout portion.

Such a throw-away drill has the advantage that the tip can be easily replaced because the tip can be mounted simply by inserting the shaft portion of the tip into the round hole of the tip mounting seat. However, since the tip and the drill body are only connected via the shaft, the tip positioning (centering) accuracy with respect to the drill body is insufficient, and the drilling accuracy for the workpiece is reduced. There was a risk of adverse effects.
JP 11-197923 A

Therefore, the present applicant has proposed a throw-away drill as shown in the application specification of Japanese Patent Application No. 2002-330575.
As shown in FIG. 15, this throw-away drill has a pair of chip discharge grooves 2, 2 formed on the outer periphery of the drill body 1 rotated about the axis O, and a pair of chip discharges at the tip of the drill body 1. A recessed groove-shaped tip mounting seat 4 is formed which communicates with the grooves 2 and 2 and opens at the tip surface 3 of the drill body 1.

  Further, the chip mounting seat 4 has a chip having a substantially flat chip main body 5 having a pair of cutting edges formed at the tip thereof, and the pair of outer side surfaces 5A and 5A of the chip main body 5 are connected to the pair of chip mounting seats 4 respectively. A pair of scooping surfaces 5B and 5B, which are portions facing the inner side surfaces 4A and 4A, respectively, and facing the front side of the drill rotation direction T in the pair of outer side surfaces 5A and 5A of the tip body 5 are paired with a pair of chip discharge grooves 2 and 2. A pair of inner side surfaces of the tip mounting seat 4 with clamp bolts (only the center line L is shown) screwed into the tip of the drill body 1 so as to cross the tip mounting seat 4 diagonally while being opened inside 4A and 4A are fixedly mounted by being brought close to each other.

  A guide groove 6 extending along the axis O direction is formed in a portion of the inner side surfaces 4A and 4A of the tip mounting seat 4 facing the front side of the drill rotation direction T, and a drill on the outer side surface 5A of the tip body 5 is formed. A convex portion 7 that can be engaged with the guide groove 6 is formed in a portion facing the rear side in the rotation direction T, and the guide groove 6 and the convex portion 7 are engaged with each other, whereby the tip for the drill body 1 is inserted. It is possible to improve the positioning accuracy.

However, in the throw-away drill as shown in FIG. 15, the tip body 5 of the tip mounted on the tip mounting seat 4 is a portion facing the front side of the drill rotation direction T on the pair of outer side surfaces 5A and 5A. The pair of rake faces 5B and 5B are opened in the pair of chip discharge grooves 2 and 2, respectively.
Therefore, when the pair of inner side surfaces 4A and 4A of the chip mounting seat 4 which are brought close to each other by the clamp bolt are pressed against the pair of outer side surfaces 5A and 5A of the chip body 5 and the chip is fixedly mounted on the chip mounting seat 4 Since the pair of rake surfaces 5B and 5B of the tip body 5 are opened as described above, the tip body 5 is inevitably rotated about the axis O toward the front side in the drill rotation direction T (FIG. 15). There was a problem of protruding (as indicated by the white arrow inside).

  Therefore, the portion of the pair of outer side surfaces 5A and 5A of the tip body 5 facing the rear side in the drill rotation direction T is the portion of the pair of inner side surfaces 4A and 4A of the tip mounting seat 4 facing the front side of the drill rotation direction T. Since the contact is difficult, not only the chip cannot be firmly fixed to the chip mounting seat 4, but also a configuration in which the convex portion 7 and the guide groove 6 are engaged with each other as described above is adopted. However, the effect of improving the alignment accuracy of the tip with respect to the drill body 1 cannot be sufficiently obtained.

  The present invention has been made in view of the above-described problems, and is a throw-away method in which a tip can be firmly fixed by a clamp bolt and attached to a recessed groove-shaped tip mounting seat that opens at a tip surface of a drill body. The purpose is to provide an expression drill.

  In order to solve the above problems and achieve such an object, according to the present invention, a pair of chip discharge grooves are formed on the outer periphery of the drill body rotated about the axis, and the tip of the drill body is A recessed groove-shaped tip mounting seat that communicates with the pair of chip discharge grooves and opens at the tip end surface of the drill body is formed, and the tip mounting seat has a substantially flat plate with a pair of cutting edges formed at the tip. A chip having a chip-shaped chip body, the pair of outer surfaces of the chip body facing the pair of inner surfaces of the chip mounting seat, respectively, and facing the front side in the drill rotation direction on the pair of outer surfaces of the chip body With a pair of rake faces open into the pair of chip discharge grooves, the front end is clamped with a clamp bolt that is screwed into the tip of the drill body so as to cross the tip mounting seat. A throw-away drill that is fixedly mounted by bringing a pair of inner side surfaces of a chip mounting seat closer to each other, and a recess that does not contact the outer side surface of the chip body is provided on the inner side surface of the chip mounting seat. By being formed, the tip body is moved rearward in the drill rotation direction when the clamp bolt is screwed in adjacent to the recess so as to be positioned rearward in the drill rotation direction from the center line of the clamp bolt. A pressing portion that presses the outer surface of the chip main body so as to rotate about the axis is left behind.

According to the present invention, when the chip is fixedly mounted on the chip mounting seat by pressing the pair of outer surfaces of the chip body with the pair of inner surfaces of the chip mounting seat that are brought close to each other by the clamp bolt, The pressing portion provided on the inner side surface of the chip mounting seat by pressing the outer surface of the chip body so as to rotate the chip body about the axis toward the rear side in the drill rotation direction. It has become.
Therefore, even if the pair of rake surfaces of the chip body are opened in the pair of chip discharge grooves, the chip body of the chip mounted on the chip mounting seat is axially directed toward the front side in the drill rotation direction. The part that faces the rear side in the drill rotation direction on the pair of outer surfaces of the tip body faces the front side in the drill rotation direction on the pair of inner side surfaces of the tip mounting seat. It is possible to attach the chip firmly to the part and firmly fix the chip to the chip mounting seat.

In the present invention, a guide groove extending along the axial direction is formed in a portion facing the front side in the drill rotation direction on the inner side surface of the tip mounting seat, and the drill rotation on the outer side surface of the tip body. It is preferable that a convex portion that can mesh with the guide groove is formed in a portion facing the rear side in the direction, and the guide groove and the convex portion are meshed with each other.
With such a configuration, the serration structure can be configured by the protrusions of the chip body and the guide grooves of the chip mounting seat that are meshed with each other, and in addition, the drill rotation direction rearward of the pair of outer surfaces of the chip body as described above Since the part facing the side and the part facing the front side of the drill rotation direction on the pair of inner surfaces of the tip mounting seat are securely in close contact with each other, the convex part formed in these parts and the guide groove are securely in contact without any gap Therefore, it is possible to sufficiently improve the alignment accuracy of the tip with respect to the drill body.

In the present invention, it is preferable that an inclined portion projecting outward in the thickness direction from the front end side toward the rear end side is formed in a region received by the chip mounting seat in the chip body.
With this configuration, the tip of the drill body divided by the tip mounting seat is elastically deformed so as to be pressed inward by the clamping bolt tightening force, and the outer surface of the tip body provided on the tip mounting seat is Sandwich.
In the region of the outer surface of the chip body that is received by the chip mounting seat, there is an inclined portion that projects outward in the thickness direction from the front end side toward the rear end side. It will be in a state of protruding to the inside.
That is, in this state, the tip mounting seat is elastically deformed into a shape along the inclined portion provided on the outer side surface of the tip body, and becomes a concave groove shape that is tapered in a side view. Since the movement to the side is restricted, the tip body is prevented from dropping off from the drill body.

  At this time, a guide groove extending along the axial direction is formed in a portion facing the front side in the drill rotation direction on the inner side surface of the tip mounting seat, and facing the rear side in the drill rotation direction on the outer side surface of the tip body. A convex portion that can mesh with the guide groove is formed in the portion, and the inclined portion is formed in a region located between ridge lines of the convex portion, and the guide groove and the convex portion are It is preferable that the inclined portion and the region located between the bottom portions of the guide groove are engaged with each other by being engaged with each other.

Furthermore, at this time, it is preferable that the gradient of the inclined portion is 0 ° 01 ′ to 3 °.
If this gradient is smaller than 0 ° 01 ', the amount of deformation of the tip of the drill body is reduced, and the force for holding the tip body becomes insufficient. On the other hand, if this gradient exceeds 3 °, the inclination of the inclined portion is too tight, the deformation of the drill body cannot catch up, the adhesion between the drill body and the tip body becomes insufficient, and the holding power of the tip body decreases. End up. For this reason, this gradient is preferably within the range of 0 ° 01 ′ to 3 °.

In the present invention, a slit extending toward the rear end side in the axial direction is cut in the bottom surface of the chip mounting seat facing the front end side in the axial direction, and viewed from the front end side in the axial direction. The slit is bisected by the tip mounting seat, and the other end into which the shaft portion of the clamp bolt is screwed, rather than the one pressed by the head of the clamp bolt, of the tip end portion of the drill body. It is preferable that they are arranged so as to approach each other.
With such a configuration, first, the slit extending from the bottom surface of the chip mounting seat toward the rear end side is cut, so that the tip of the drill body divided into two by the chip mounting seat is When the pair of inner side surfaces are elastically deformed so as to approach each other, the amount of bending of each of the bisected drill body tip portions is increased, and the pair of inner side surfaces of the chip mounting seats are paired with the pair of outer side surfaces. It is possible to ensure a large pressing force when pressing.
And, this slit is arranged so as to be closer to the other side into which the shaft portion of the clamp bolt is screwed than one of the tip portions of the drill body divided into two by the tip mounting seat and pressed by the head portion of the clamp bolt. As a result, there is a difference in the cross-sectional area of the drill body located on both sides across the slit, so that one tip portion pressed by the head of the clamp bolt is connected to the other end into which the shaft portion of the clamp bolt is screwed. It becomes harder to bend than the tip.
Therefore, the bending of one tip portion, which tends to bend due to being pressed by the head of the clamp bolt, and the bending of the other tip portion, which tends to bend due to the shaft portion of the clamp bolt being screwed, are mutually connected. Easily set to approximately the same amount, with the pair of inner surfaces of the tip mounting seats located on each of the bisected drill bodies, the pressing forces when pressing the pair of outer faces of the tip body are uniform to each other Thus, the chip body can be firmly clamped (fixed), and the cutting edge runout accuracy can be kept good.
At this time, the crossing angle between the extending direction of the slit and the extending direction of the clamp bolt when viewed from the front end side in the axial direction is preferably set in a range of 90 ° ± 15 °. .

Embodiments of the present invention will be described below with reference to the accompanying drawings.
The drill body 10 of the throw-away drill according to the present embodiment has an axis O that is rotated around the axis O such that the distal end side portion is reduced in diameter by one step with respect to the shank portion (not shown) that is the rear end side portion. It has a substantially multi-stage cylindrical shape with a center.
On the outer periphery of the tip side portion of the drill body 10, a pair of chip discharge grooves 12, 12 that open to the tip surface 11 of the drill body 10 are on opposite sides of the axis O and on the rear end side in the axis O direction. It is formed in a spiral shape so as to twist toward the rear side in the drill rotation direction T as it goes.

Further, the tip portion 13 of the drill body 10 is provided with a groove mounting tip 14 that is open to the tip surface 11 of the drill body 10 and is recessed toward the rear end, with respect to the axis O (through the axis O). It is formed to extend in the direction.
The tip mounting seat 14 faces the distal end side in the direction of the axis O and is perpendicular to the axis O, and is erected from the bottom surface 14A, and is parallel to the axis O and intersects the distal end surface 11 of the drill body 10. And a pair of inner side surfaces 14B, 14B. As seen in a side view along the bottom surface 14A and the inner side surfaces 14B, 14B, as shown in FIG. It is designed to open in a letter shape.
Here, the pair of inner side surfaces 14B and 14B are substantially parallel to each other when the chip body 30 is not mounted.

  More specifically, the tip mounting seat 14 is configured such that, at the distal end portion 13 of the drill body 10, the distance between the wall surfaces facing the front side in the drill rotation direction T on the distal end side of the chip discharge grooves 12, 12 is relative to the axis O (the axis O It is formed so as to be cut out in the diametrical direction, and is communicated with the chip discharge grooves 12 and 12 at both ends in the extending direction M (diameter direction with respect to the axis O). Yes.

  That is, in the tip mounting seat 14 extending in the diametrical direction with respect to the axis O, the bottom surface 14A has a pair of outer peripheral end portions located on both end sides in the extending direction M intersecting the outer peripheral surface of the drill body 10, respectively. On the other hand, each of the pair of inner side surfaces 14B, 14B is one outer peripheral side located at a portion directed to the front side in the drill rotation direction T among the pair of outer peripheral end portions located at both ends in the extending direction M. Only the end portion intersects the outer peripheral surface of the drill main body 10, and the other outer peripheral end portion intersects the wall surface facing the rear side of the drill rotation direction T in the chip discharge groove 12 without reaching the outer peripheral surface of the drill main body 10. It is.

  Further, by forming such a recessed groove-shaped tip mounting seat 14 at the tip portion 13 of the drill body 10, the tip portion 13 of the drill body 10 is divided into a first tip portion 13A and a second tip portion 13B. The bottom end 14A of the tip mounting seat 14 is positioned between the first tip portion 13A and the second tip portion 13B, and the tip mounting seat is located on the first tip portion 13A side. 14, one of the pair of inner side surfaces 14B and 14B is in a state where the other of the pair of inner side surfaces 14B and 14B is positioned on the second tip portion 13B side.

  Further, as shown in FIGS. 3 and 5, the tip end 13 of the drill body 10 is inserted through the tip mounting seat 14 so as to extend in the diameter direction with respect to the axis O in order to screw a clamp bolt 40 described later. A hole 20 is provided, and the insertion hole 20 penetrates the tip portion 13 so that the outer peripheral side end portion in the extending direction L is the outer peripheral surface of the first tip portion 13A and the second tip portion 13B, respectively. It is opened to the outer peripheral surface.

The insertion hole 20 is formed so as to extend in the diametrical direction with respect to the axis O similarly to the chip mounting seat 14, but the extending direction L is shown in FIG. 5 when viewed from the front end side in the axis O direction. As shown, it is not parallel to the width direction N of the chip mounting seat 14, which is a direction orthogonal to the extending direction M of the chip mounting seat 14, but inclined obliquely with respect to the width direction N of the chip mounting seat 14. It is supposed to be.
In particular, the extending direction L of the insertion hole 20 is from a state parallel to the width direction N of the tip mounting seat 14 passing through the axis O, as shown in FIG. It is formed so as to be rotated and moved forward by an angle α (0 ° <α ≦ 30 °) (the extending direction L of the insertion hole 20 and the width direction N of the chip mounting seat 14). Is set in the range of 0 ° <α ≦ 30 °).

  In the insertion hole 20, a portion located in the first tip portion 13 </ b> A is directed from the outer peripheral surface of the first tip portion 13 </ b> A toward the inner side in the extending direction L with a constant inner diameter (diameter inner side with respect to the axis O). A recess 21 extending so as to be recessed by one step, and a contiguous inner diameter that is one step smaller than the inner diameter of the recess 21 and extending toward the inner side in the extending direction L to the inner side surface 14B of the chip mounting seat 14 The opening 21 is configured to be open, and the connection portion of the recess 21 with the hole 22 is tapered such that the inner diameter of the recess 21 gradually decreases as it extends inward in the extending direction L. The surface is 21A.

  On the other hand, in the insertion hole 20, a portion located in the second tip portion 13 </ b> B is inside the extending direction L with a constant inner diameter from the outer peripheral surface of the second tip portion 13 </ b> B (inner diameter side in the diameter direction with respect to the axis O). The internal thread portion 23 extends so as to be recessed one step toward the inside surface 14B of the chip mounting seat 14 (in the insertion hole 20, the portion located in the second tip portion 13B is the portion of the second tip portion 13B). It may be a blind hole that does not open on the outer peripheral surface).

In the present embodiment, a slit 17 extending toward the rear end side in the axis O direction is cut into the bottom surface 14A of the chip mounting seat 14 facing the front end side in the axis O direction so as to be parallel to the axis O. ing.
The slit 17 intersects the wall surfaces of the chip discharge grooves 12 and 12 at both ends in the extending direction K (the direction in which the slit 17 extends when viewed from the front end side in the direction of the axis O). The discharge grooves 12 and 12 are communicated with each other.

Further, as shown in FIG. 5, the slit 17 does not extend in the diameter direction with respect to the axis O as viewed from the tip side in the axis O direction, but approaches the second tip 13 </ b> B rather than the first tip 13 </ b> A. The distance X between the extending direction K of the slit 17 passing through the central portion in the width direction of the slit 17 and the axis O is the displacement amount X. It is.
Similarly, as shown in FIG. 5 when viewed from the front end side in the axis O direction, the extending direction K of the slit 17 and the extending direction L of the insertion hole 20 (the extension of a clamp bolt 40 to be described later inserted through the insertion hole 20). The crossing angle with the current direction is set to about 90 °.

Further, the bottom portion 17A of the slit 17 has a semicircular arc shape that is concave toward the rear end side in the axis O direction so that a pair of opposing wall surfaces constituting the slit 17 are smoothly connected to each other. ing.
In addition, the depth Y1 of the slit 17 (the length along the axis O direction from the opening of the slit 17 to the bottom surface 14A of the chip mounting seat 14 to the bottom of the bottom 17A of the slit 17) is 3 mm to 15 mm. The width Y2 of the slit 17 (the length along the direction perpendicular to the extending direction K of the slit 17 between a pair of opposing wall surfaces constituting the slit 17) is 0.1 mm. It is set in the range of ˜1 mm.

  Here, a tip which will be described later is formed on the tip surface 11 of the drill body 10 such that a cross ridge line portion between the tip surface 11 and the wall surface facing the rear side in the drill rotation direction T in the chip discharge grooves 12 and 12 is cut out. Main body side thinning surfaces 11A and 11A that are continuous with the thinning surface 31A of the main body 30 are formed, and the pair of inner side surfaces 14B and 14B in the tip mounting seat 14 that intersects the distal end surface 11 of the drill main body 10 are formed on the main body side thinning. The planes 11A and 11A also intersect.

  A plurality of guide grooves 15 extending along the direction of the axis O are formed in each of the pair of inner side surfaces 14B, 14B of the chip mounting seat 14 so as to be arranged at predetermined intervals in a direction orthogonal to the axis O. However, in each of the pair of inner side surfaces 14B, 14B, the main body side thinning surfaces 11A, 11A are connected to the rear end side (in the direction of the axis O) (the front end side is the main end side thinning surfaces 11A, 11A). The above-mentioned guide grooves 15 are not formed in the portion intersecting with (1), and a flat surface shape (strictly, a multi-step flat surface shape is formed by forming a recess 50 described later) is formed.

  That is, each of the pair of inner side surfaces 14B and 14B in the chip mounting seat 14 includes the other outer peripheral end portion intersecting the wall surface of the chip discharge groove 12 of the pair of outer peripheral end portions (near the axis O). The drill includes a portion excluding the portion connected to the rear end side of the main body side thinning surface 11A, that is, one outer peripheral end portion that intersects the outer peripheral surface of the drill main body 10 of the pair of outer peripheral end portions. A plurality of the above-described guide grooves 15 are formed in a portion directed to the front side in the rotational direction T.

  Therefore, when the drill body 10 is viewed from the distal end side when viewed from the distal end side in the axis O direction, as shown in FIG. 2, the cross ridge lines between the pair of inner side surfaces 14B and 14B and the main body side thinning surfaces 11A and 11A are respectively A straight line (strictly speaking, a multi-stage straight line is formed by forming a recess 50 to be described later), and the pair of inner side surfaces 14B and 14B and the front end surface 11 excluding the main body side thinning surfaces 11A and 11A. The ridge line portion has a wave shape reflecting the shapes of the plurality of guide grooves 15.

  Further, in the present embodiment, each of the pair of inner side surfaces 14B, 14B in the chip mounting seat 14 is closer to the other outer peripheral end that intersects the wall surface of the chip discharge groove 12 of the pair of outer peripheral end. The part is adjacent to the part in which the plurality of guide grooves 15 are formed (the part facing the front side of the drill rotation direction T on the inner side surface 14) in the extending direction M of the tip mounting seat 14, A recess 50 is formed in which a part of each inner surface 14B is recessed by a predetermined constant depth.

  The recess 50 is formed in each of the pair of inner side surfaces 14B, 14B so as not to reach the other outer peripheral end that intersects the wall surface of the chip discharge groove 12 of the pair of outer peripheral ends. Therefore, a portion connected to the other outer peripheral side end portion of the inner side surface 14B remains as a pressing portion 51 for pressing the outer side surface 34 of the chip body 30 described later.

That is, each of the pair of inner side surfaces 14B and 14B of the chip mounting seat 14 is adjacent to the plurality of guide grooves 15 and the pressing portions 51 on both sides thereof through the recess 50 in the extending direction M of the chip mounting seat 14. The portions where the plurality of guide grooves 15... And the recesses 50 are not formed in each inner side surface 14 </ b> B are the pressing portions 51.
Here, when viewed from the front end side in the direction of the axis O, the length of the pressing portion 51 along the extending direction M of the chip mounting seat 14 is set to about 1 mm, for example.

  At this time, as shown in FIG. 2, the pressing portion 51 as viewed from the distal end side in the direction of the axis O is extended in the whole area from the extending direction L of the insertion hole 20 (a center line L of a clamp bolt 40 described later). It is made to adjoin the recessed part 50 so that it may be located in the drill rotation direction T back side, and especially in this embodiment, the press part 51 is the width direction N of the chip | tip mounting seat 14 in which the whole region passes along the axis line O. Is also located adjacent to the recess 50 so as to be positioned behind the drill rotation direction T.

  In addition, the outer peripheral surface of the drill main body 10 defined between the pair of chip discharge grooves 12 and 12 is cut out at the distal end portion 13 of the drill main body 10, so that the axis O extends from the rear end of the drill main body 10. The coolant discharge parts 16 and 16 are formed in which coolant holes that extend and branch in the middle are opened. During drilling, coolant is supplied to the cutting site through the coolant discharge parts 16 and 16.

  On the other hand, the chip body 30 of the chip fixed and attached to the chip mounting seat 14 is formed in a substantially flat pentagonal flat plate shape as shown in FIG. 6 from a hard material such as cemented carbide. A portion from the substantially central portion to the rear end surface 32 is cut out so as to obliquely intersect the thickness direction of the chip body 30, whereby a cutout portion 33 into which a clamp bolt 40 described later is inserted. Is formed.

  Further, the tip surface 31 of the chip body 30 is formed to form an isosceles triangle shape (V-shape) that gradually recedes from the axis O toward the outer peripheral side with the chip mounted on the chip mounting seat 14. In addition, the tip end surface 31 and the pair of outer side surfaces 34, 34 of the tip body 30 are respectively crossed ridge lines with the portions which are the scooping surfaces 34A, 34A facing the front side of the drill rotation direction T, respectively. Cutting blades 35 and 35 are formed.

Here, the tip surface 31 of the chip body 30 has a rake face 34A and other portions in each of the pair of outer surfaces 34 and 34 from the vicinity of the axis O located at the center of the tip surface 31 in the chip mounting state. A portion up to the vicinity of the crossing is cut out, so that a pair of thinning surfaces 31A and 31A located on opposite sides of the axis O are formed.
As a result, the thinning cutting edge portions 35A and 35A formed at the intersecting ridge line portion between the pair of thinning surfaces 31A and 31A and the front end surface 31 are connected to the inner peripheral ends of the cutting edges 35 and 35 from the front end surface. It arrange | positions so that it may extend toward the axis line O located in the center of 31. FIG.

  A plurality of projections 36 extending along the axis O direction in a state where the chip is mounted are predetermined in the direction orthogonal to the axis O on each of the portions of the pair of outer surfaces 34, 34 other than the rake surfaces 34A, 34A. The rear ends (in the direction of the axis O) of the thinning surfaces 31A and 31A are formed so as to be arranged at intervals, in the portions other than the rake surfaces 34A and 34A in the pair of outer surfaces 34 and 34, respectively. The portion connected to the side (the portion where the tip side intersects with the thinning surfaces 31A, 31A) is formed with a flat surface shape without the above-described convex portions.

  That is, each of the portions of the pair of outer surfaces 34, 34 of the chip body 30 other than the rake surfaces 34A, 34A is connected to the rear end side of the thinning surface 31A (located in the vicinity of the axis O) in the mounted state. Is formed by arranging a plurality of the convex portions 36... In a portion except the rake face 34 A directed to the front side of the drill rotation direction T and directed to the rear side of the drill rotation direction T. -ing

  Therefore, when the chip main body 30 is viewed from the front end side in the direction of the axis O with the chip mounted, as shown in FIG. 7, a portion other than the rake surfaces 34A and 34A on the pair of outer surfaces 34 and 34 is thinned. The intersecting ridge line portions with the surfaces 31A and 31A are respectively linear, and the intersection between the pair of outer surfaces 34 and 34 other than the rake surfaces 34A and 34A and the tip surface 31 excluding the thinning surfaces 31A and 31A. The ridge line portion has a wave shape reflecting the shapes of the plurality of convex portions 36.

  In the chip body 30, the region received by the chip mounting seat 14 (the region in which the convex portions 36 are formed in the present embodiment) is rearward from the front end side in the axis O direction as shown in FIG. An inclined portion 37 that protrudes outward in the thickness direction as it goes toward the end side is provided. In the present embodiment, an inclined portion 37 is formed in a region located between the ridge lines of the convex portions 36..., And the region located in the ridge line of the convex portions 36. It is almost parallel. Further, the gradient of the inclined portion 37 is set to 0 ° 01 ′ to 3 °.

In the chip body 30 having such a configuration, the thickness direction of the chip body 30 is the width direction N of the chip mounting seat 14 (chips) with respect to the recessed groove-shaped chip mounting seat 14 formed at the tip of the drill body 10. It is inserted by being slid toward the rear end side in the direction of the axis O in a state parallel to the extending direction M of the mounting seat 14.
Further, the chip body 30 is inserted by engaging the guide grooves 15 formed on the inner side surfaces 14B and 14B of the chip mounting seat 14 with the convex portions 36 formed on the outer side surfaces 34 and 34 of the chip body 30. It is done while.

  Thereby, the rear end surface 32 of the chip body 30 is disposed opposite to the bottom surface 14A of the chip mounting seat 14 and brought into close contact with each other, and the rake surfaces 34A and 34A on the outer surfaces 34 and 34 of the chip body 30 are respectively While being opened in the chip discharge grooves 12 and 12 and directed to the front side in the drill rotation direction T, portions of the outer side surfaces 34 and 34 of the tip body 30 other than the rake surfaces 34A and 34A are the inner side surfaces of the tip mounting seat 14, respectively. 14B and 14B are arranged opposite to each other.

  At this time, among the portions other than the rake surfaces 34A and 34A on the outer side surfaces 34 and 34 of the tip body 30, the portion where the plurality of convex portions 36... 14 of the inner side surfaces 14B, 14B of the fourteen are formed so as to face the front side of the drill rotation direction T and are formed to be opposed to each other, and the convex portions 36 and the guide grooves 15. A state in which they are engaged with each other (a state in which an inclined portion 37 formed in a region located between the ridge lines of the convex portions 36 and a region located between the bottom portions of the guide grooves 15 are engaged with each other) It has become.

  Further, at this time, of the portions other than the rake surfaces 34A and 34A on the outer surfaces 34 and 34 of the chip body 30, the flat surface portion connected to the rear end side of the thinning surfaces 31A and 31A is the portion of the chip mounting seat 14. Of the inner side surfaces 14B, 14B, the flat surface portions that continue to the rear end side of the main body side thinning surfaces 11A, 11A are respectively arranged to face each other, and the thinning surfaces 31A that are continuous to the front end side of these flat surface portions. 31A and the main body side thinning surfaces 11A and 11A are in a continuous state.

  A clamp bolt 40 is inserted into the tip mounting seat 14 with respect to the insertion hole 20 provided at the tip portion 13 of the drill body 10 and intersecting the tip mounting seat 14 so as to be inclined obliquely with respect to the width direction N thereof. It is inserted through the opening to the outer peripheral surface of the first tip portion 13A in the insertion hole 20 so as to penetrate the notch 33 of the inserted chip body 30.

  The clamp bolt 40 is located at the rear end of the head 41 having a substantially cylindrical shape having a constant outer diameter, and is connected to the distal end side of the head 41 and has a constant outer diameter that is one step smaller than the outer diameter of the head 41. It has a substantially cylindrical shape having a diameter, and a tip portion on the tip side part of which is formed of a shaft portion 42 which is a male screw portion 43. The head portion 41 has a connecting portion with the shaft portion 42. The taper surface 41A is formed such that the outer diameter of the head 41 gradually decreases as it goes toward the distal end.

When the clamp bolt 40 is inserted into the insertion hole 20 as described above and the male screw portion 43 of the shaft portion 42 of the clamp bolt 40 is screwed into the female screw portion 23 of the insertion hole 20, the head 41 is inserted into the insertion hole 20. While being accommodated in the recess 21, the taper surface 41 </ b> A in the head 41 and the taper surface 21 </ b> A in the recess 21 are arranged to face each other.
As it is, by screwing the male screw portion 43 in the shaft portion 42 of the clamp bolt 40 into the female screw portion 23 in the insertion hole 20, the taper surface 41 </ b> A in the head 41 of the clamp bolt 40 is in the recess 21 of the insertion hole 20. A force is applied to the taper surface 21A so as to press the taper surface 21A inward in the extending direction L of the insertion hole 20, and the male screw portion 42 of the shaft portion 42 of the clamp bolt 40 is inserted. The screw 20 is screwed into the female screw part 23 of the hole 20, and a force is applied to pull the female screw part 23 toward the inner side in the extending direction L of the insertion hole 20.

  Therefore, the first tip portion 13A in which the recess 21 in the insertion hole 20 is formed is the second tip portion 13B in which the female screw portion 23 in the insertion hole 20 is formed, as indicated by the arrow 1 in FIG. 4 are elastically deformed so as to approach each other toward the inner side in the extending direction L of the insertion hole 20 as indicated by an arrow 2 in FIG. 4, and accordingly, the tip located on the first tip portion 13A side. The inner side surface 14B of the mounting seat 14 and the inner side surface 14B of the chip mounting seat 14 located on the second tip portion 13B side are brought close to each other, and the pair of outer side surfaces 14B, 14B of the chip mounting seat 14 are a pair of the chip body 30. The outer side surfaces 34 and 34 are pressed firmly.

  Here, in the present embodiment, the recesses 50, 50 as described above are provided on each of the pair of inner side surfaces 14B, 14B of the chip mounting seat 14, so that these recesses 50, 50 are outside the chip body 30. Instead of contacting the side surfaces 34, 34, the pressing portions 51, 51 adjacent to the recesses 50, 50 contact the outer side surfaces 34, 34 of the chip body 30 instead.

  As described above, the pressing portions 51 and 51 are located on the rear side in the drill rotation direction T with respect to the center line L (the extending direction L of the insertion hole 20) of the clamp bolt 40 when viewed from the front end side in the axis O direction. Since these pressing portions 51 and 51 press the outer side surfaces 34 and 34 of the chip body 30, the chip body 30 inserted into the chip mounting seat 14 is rearward in the drill rotation direction T. A force (such as indicated by a hollow arrow in FIG. 2) that is rotated around the axis O toward the side is received.

In addition, in the region of the outer surface 34 of the chip body 30 that is received by the chip mounting seat 14, an inclined portion 37 that projects outward in the thickness direction from the front end side toward the rear end side is provided. As shown in FIG. 4, the front end side protrudes inward from the rear end side.
In other words, in this state, the chip mounting seat 14 is elastically deformed into a shape along the inclined portion 37 provided on the outer side surface 34 of the chip body 30 and becomes a groove shape that is tapered in a side view.

  Accordingly, the plurality of convex portions 36 formed in the portion facing the front side of the drill rotation direction T in the pair of outer surfaces 34, 34 of the tip body 30, and the drill in the pair of outer surfaces 14 B, 14 B of the chip mounting seat 14. A plurality of guide grooves 15 formed in a portion facing the rear side in the rotation direction T are in close contact with each other (an inclined portion 37 formed in a region located between ridge lines of the plurality of convex portions 36. And the region located between the bottoms of the plurality of guide grooves 15 are engaged with each other), and the chip is fixedly mounted to the chip mounting seat 14.

  As described above, according to the throw-away drill of the present embodiment, the pair of outer side surfaces 34, 34 of the chip body 30 are formed by the pair of inner side surfaces 14 B, 14 B of the chip mounting seat 14 that are brought closer to each other by the clamp bolt 40. When the chip is pressed and fixed to the chip mounting seat 14, the pressing portions provided on the inner side surfaces 14B and 14B of the chip mounting seat 14 are formed by forming the recesses 50 and 50 as described above. 51 and 51 press the outer side surfaces 34 and 34 of the chip body 30 so as to rotate the chip body 30 around the axis O toward the rear side in the drill rotation direction T.

  Therefore, even if the pair of rake faces 34A and 34A of the chip body 30 are opened in the pair of chip discharge grooves 12 and 12, respectively, the chip body 30 of the chip mounted on the chip mounting seat 14 is provided. Since it does not protrude so as to be rotated around the axis O toward the front side in the drill rotation T direction as in the prior art, the drill rotation direction T rearward of the pair of outer side surfaces 34, 34 of the tip body 30 is eliminated. The tip-facing portion is securely brought into close contact with the portion facing the front side of the drill rotation direction T in the pair of inner side surfaces 14B, 14B of the tip mounting seat 14, and the tip is firmly fixed and attached to the tip mounting seat 14. be able to.

  Further, in the throw-away drill of this embodiment, by tightening the clamp bolt 40, the tip mounting seat 14 is elastically deformed into a shape along the inclined portion 37 provided on the outer side surface 34 of the tip body 30, and the side surface It becomes a concave groove shape that is tapered as viewed, and this restricts the movement of the tip body 30 toward the distal end side of the drill body 10 and reliably prevents the tip body 30 from falling off the drill body 10.

  Here, in the tip body 30, if the slope of the inclined portion 37 is smaller than 0 ° 01 ′, the amount of deformation of the tip portion of the drill body 10 is reduced, and the force for holding the tip body 30 becomes insufficient. End up. On the other hand, if this gradient exceeds 3 °, the inclination of the inclined portion 37 is too tight, the deformation of the drill body 10 cannot catch up, the adhesion between the drill body 10 and the tip body 30 becomes insufficient, and the tip body 30 is held. Power will be reduced. For this reason, this gradient is preferably within the range of 0 ° 01 ′ to 3 ° (more preferably within the range of 1/100 to 2/100).

  In such a chip body 30, the protrusions 36 are formed by regions left by being formed by forming grooves on the pair of outer surfaces 34, 34 of the chip body 30 by grinding or the like. Is. The inclined portion 37 formed between the convex portions 36 is simply moved at a desired inclination with respect to the outer surface 34 in the grinding process for forming the convex portions 36. It can be formed easily.

Furthermore, in the throw-away drill of this embodiment, since the slit 17 is cut into the bottom surface 14A of the tip mounting seat 14, the clamp bolts are arranged so that the pair of inner side surfaces 14B and 14B of the tip mounting seat 14 approach each other. When the first tip portion 13A and the second tip portion 13B of the drill main body 10 are elastically deformed at 40, the bottom portion 17A of the slit 17 is formed at the time of elastic deformation of the first tip portion 13A and the second tip portion 13B. A fulcrum.
Therefore, compared to the case where the slit 17 is not cut, the fulcrum when the first tip portion 13A and the second tip portion 13B are elastically deformed is shifted to the rear end side in the axis O direction. Ensuring that the bending amount of the tip portion 13A and the second tip portion 13B is sufficiently large and increasing the pressing force when pressing the outer surfaces 34, 34 of the chip body 30 with the inner surfaces 14B, 14B of the chip mounting seat 14. Can do.

  Further, the slit 17 has an extending direction K that intersects the extending direction L of the insertion hole 20 (the extending direction of the clamp bolt 40) with an intersection angle of about 90 °. When the clamp tip 40 elastically deforms the first tip portion 13A and the second tip portion 13B inward in the extending direction L of the insertion hole 20, the first tip portion 13A and the second tip portion 13B are elastic. It becomes easy to deform | transform, and the pressing force at the time of pressing the outer side surfaces 34 and 34 of the chip body 30 with the inner side surfaces 14B and 14B of the chip mounting seat 14 is further increased.

Further, since the bottom portion 17A of the slit 17 has a semicircular arc shape that is concave toward the rear end side in the axis O direction, the first tip portion 13A and the second tip portion 13B are elastically deformed by the clamp bolt 40. It is possible to alleviate the stress concentration that occurs when it is applied.
Note that the shape of the bottom portion 17A of the slit 17 that can relieve stress concentration is not limited to such a shape having a semicircular arc shape in cross section. For example, as shown in FIG. The bottom 17A having a circular cross section having a width larger than the width Y2 of 17 (the length along the direction perpendicular to the extending direction K of the slit 17), as shown in FIG. Although various things, such as the bottom part 17A of the cross-sectional ellipse shape which has a width | variety larger than this width Y2, can be considered, it is preferable that the width | variety of the bottom part 17A is set to 5 mm or less in any case.

  Further, since the depth Y1 of the slit 17 is set in the range of 3 mm to 15 mm, the width Y2 of the slit 17 is set in the range of 0.1 mm to 1 mm, and the slit 17 having an appropriate shape is formed, the first The amount of bending of each of the tip portion 13A and the second tip portion 13B is increased to sufficiently increase the pressing force when pressing the outer surfaces 34, 34 of the chip body 30 with the inner surfaces 14B, 14B of the chip mounting seat 14. Although it is possible, there is no problem that the rigidity of the drill body 10 is impaired.

  In the present embodiment, the slit 17 is arranged so as to be shifted from the axis O by a deviation amount X so as to approach the second tip portion 13B rather than the first tip portion 13A when viewed from the tip side in the direction of the axis O. In the cross-sectional area of the cross section perpendicular to the axis O of the drill body 10 located on both sides of the slit 17, the portion located on the first tip portion 13A side is located on the second tip portion 13B side. It is larger than the part to be.

  Therefore, the first tip portion 13A that is elastically deformed so as to be pressed toward the inner side in the extending direction L of the insertion hole 20 by being pressed by the head 41 of the clamp bolt 40, and tends to have a large deflection. And the internal thread portion 43 of the clamp bolt 40 is screwed in, so that it is elastically deformed so as to be pulled inward in the extending direction L of the insertion hole 20, and the bending tends to be small. The two tip portions 13B can be easily bent, and the bending of the first tip portion 13A and the bending of the second tip portion 13B can be set to substantially the same amount.

  For this reason, a pair of the chip body 30 is constituted by the inner side surface 14B of the chip mounting seat 14 positioned on the first tip portion 13A side and the inner side surface 14B of the chip mounting seat 14 positioned on the second tip portion 13B side. The pressing force when pressing the outer surfaces 34, 34 becomes uniform with each other, the chip body 30 is firmly fixed (clamped) to the chip mounting seat 14, and the cutting edge runout accuracy is maintained at a high level. can do.

Here, the amount of deviation X of the slit 17 is set so that the bending of the first tip portion 13A and the bending of the second tip portion 13B are substantially equal to each other in accordance with various shapes of the throw-away drill. For example, when the slit 17 has a depth of 5 mm and a width of 0.7 mm, the outer diameter D of the cutting edge 35 (around the axis O of the cutting edge 35). When the outer diameter formed by the rotation locus is 15 mm, the deviation amount X should be set to about 0.5 mm, and when the outer diameter D of the cutting blade 35 is 25 mm, The deviation amount X should be set to about 0.8 mm.
The appropriate shift amount X of the slit 17 increases in proportion to the outer diameter D of the cutting edge 35, and is, for example, 1 with respect to the outer diameter D of the cutting edge 35. By appropriately setting the deviation amount X within the range of 10% to 10% (preferably 1% to 5%), the deflection of the first tip portion 13A and the deflection of the second tip portion 13B are set to substantially the same amount. (In the above example, the amount of deviation X of the slit 17 is set to about 3% with respect to the outer diameter D of the cutting edge 35).

  Further, in the throw-away drill of the present embodiment, the outer side surfaces 34, 34 of the tip body 30 are formed in the plurality of guide grooves 15 extending along the axis O direction formed on the inner side surfaces 14B, 14B of the tip mounting seat 14. The chip body 30 can be easily mounted by simply sliding the chip body 30 toward the rear end side in the direction of the axis O with respect to the chip mounting seat 14 while engaging the plurality of convex portions 36. It is possible.

  As described above, the portions where the protrusions 36 are formed (portions facing the rear side in the drill rotation direction T on the pair of outer surfaces 34, 34 of the tip body 30) and the portions where the guide grooves 15 are formed (chips). Since the pair of inner side surfaces 14B, 14B of the mounting seat 14 are in close contact with each other, the portion facing the front side of the drill rotation direction T, the protrusions 36 and the guide grooves 15 are engaged with each other. It is possible to eliminate the occurrence of gaps and backlash in the configured serration structure, and to sufficiently improve the alignment accuracy of the tip with respect to the drill body 10.

  In addition, since the serration structure as described above is configured, the contact area between the chip body 30 and the chip mounting seat 14 is increased, and the mounting rigidity of the chip body 30 is improved. Even when the workpiece is drilled by being rotated around O, it is possible to suppress the positional deviation of the tip body 30 and to effectively and reliably transmit the rotational force of the drill body 10.

Furthermore, in the present embodiment, portions of the outer surfaces 34, 34 of the chip body 30 that are connected to the rear end sides of the thinning surfaces 31A, 31A have a flat surface shape, and the inner surfaces 14B, 14B of the chip mounting seat 14 have a main body. Since the portion connected to the rear end side of the side thinning surfaces 11A and 11A is also a flat surface, the connecting portion between the thinning surface 31A of the tip body 30 and the main body side thinning surface 11A of the drill body 10 is viewed in the front end view. A straight serration structure in which the convex portions 36 and the guide grooves 15 are meshed with each other does not appear at the connecting portion between the thinning surface 31A and the main body side thinning surface 11A.
Therefore, even when the chips generated from the thinning cutting edge portion 35 flow out from the thinning surface 31A through the main body side thinning surface 11A during drilling, the thinning surface 31A and the main body side thinning surface 11A It is difficult to cause a phenomenon such as being caught at the connecting portion, and the scrubbing of the drill body 10 is not promoted, and the chip discharging property is not deteriorated.

In the present embodiment, the recesses 50 and 50 formed in the pair of inner side surfaces 14B and 14B in the chip mounting seat 14 are formed by recessing a part of the inner side surface 14B by a predetermined constant depth. However, the present invention is not limited to this, and as shown in FIG. 10, for example, the recess 50 is recessed so that a part of each inner side surface 14B gradually becomes shallow toward the other outer peripheral end. It may be.
In short, the concave portions 50 having a shape that allows the pressing portion 51 to remain without damaging the rigidity of the distal end portion 13 of the drill body 10 are provided on the pair of inner side surfaces 14B, 14B of the tip mounting seat 14, respectively. It is enough to form it.

  Further, in the present embodiment, the crossing angle formed by the extending direction K of the slit 17 and the extending direction L of the insertion hole 20 (the extending direction of the clamp bolt 40) when viewed from the front end side in the axis O direction is Although it is set to about 90 °, the present invention is not limited to this, and the crossing angle between the extending direction K of the slit 17 and the extending direction L of the insertion hole 20 is the first modification shown in FIG. Alternatively, as in the second modification shown in FIG. 12, it may be set within the range of 90 ° ± 15 °.

  In the first modification shown in FIG. 11, when viewed from the front end side in the axis O direction, the extension direction K of the slit 17 and the extension direction L of the insertion hole 20 (extension direction of the clamp bolt 40) are formed. From the state where the crossing angle is 90 °, the extending direction K of the slit 17 is rotated and moved by an angle β (0 ° <β ≦ 15 °) toward the front side of the drill rotation direction T. This slit 17 is formed.

According to the first modification, when the first tip portion 13A and the second tip portion 13B are elastically deformed by the clamp bolt 40, the extending direction K of the slit 17 is inclined as described above. As shown by an arrow 1 in FIG. 11, the first tip 13A is exaggerated, and as shown by an arrow 2 in FIG. 11, the second tip 13B is directed toward the front side in the drill rotation direction T. It will be elastically deformed so that it may mutually approach toward the inner side of the extending direction L of the insertion hole 20 while inclining.
Therefore, the inner side surfaces 14B and 14B of the chip mounting seat 14 can press the outer side surfaces 34 and 34 of the chip main body 30 substantially along the width direction N of the chip mounting seat 14, and the above-described convex portions 36 and The guide groove 15 is brought into close and firm contact with each other, and the effect that the cutting edge runout accuracy of the chip body 30 can be kept good is obtained.

  In the second modification shown in FIG. 12, when viewed from the front end side in the axis O direction, the extension direction K of the slit 17 and the extension direction L of the insertion hole 20 (extension direction of the clamp bolt 40) are formed. From the state in which the crossing angle is 90 °, the extending direction K of the slit 17 is rotated and moved by the angle β (0 ° <β ≦ 15 °) toward the rear side of the drill rotation direction T. This slit 17 is formed.

According to the second modification, when the first tip portion 13A and the second tip portion 13B are elastically deformed by the clamp bolt 40, the extending direction K of the slit 17 is inclined as described above. As shown in FIG. 12, the first tip 13A is exaggerated by the arrow 1 in FIG. 12, and the second tip 13B is exaggerated by the arrow 2 in FIG. It will be elastically deformed so that it may mutually approach toward the inner side of the extending direction L of the insertion hole 20 while inclining.
Therefore, the inner side surfaces 14B, 14B of the tip mounting seat 14 are substantially along the direction toward the rear side of the drill rotation direction T as the outer side surfaces 34, 34 of the tip body 30 are increased inward in the diameter direction with respect to the axis O. It is possible to press, and one of the two side surfaces constituting the convex portion 36 and one of the two side surfaces constituting the guide groove 15 are firmly brought into close contact with each other. The effect that the cutting blade runout accuracy of 30 can be kept good is obtained.

  Further, in the present embodiment, the extending direction L of the insertion hole 20 is inclined obliquely with respect to the width direction N of the chip mounting seat 14 as viewed from the front end side in the axis O direction. Without being limited thereto, the extending direction L of the insertion hole 20 may be parallel to the width direction N of the chip mounting seat 14 (the extending direction L of the insertion hole 20 and the tip mounting seat 14 The crossing angle α made with the width direction N becomes 0 °).

  Furthermore, in this embodiment, although the example which formed the slit 17 in the drill main body 10 was shown, the slit 17 does not need to be formed in the drill main body 10.

Moreover, in this embodiment, although the example which formed the inclination part 37 in the area | region located between the ridgelines of the convex part 36 ... in the chip | tip body 30 was shown, it is not limited to this, For example, FIG. Instead of forming the inclined portion 37 in the region located between the ridge lines of the convex portions 36... Like the chip main body 30 shown, the region located between the ridge lines of the convex portions 36. The outer surface 34 itself, which is a region formed of a region located on the ridge line, may be the inclined portion 37.
Even in this case, by tightening the clamp bolt 40, the tip mounting seat 14 provided in the drill body 10 is elastically deformed into a shape along the inclined portion 37 of the tip body 30, and becomes a concave groove that is tapered in a side view. As a result, the movement of the tip body 30 toward the distal end side of the drill body 10 is restricted, and the tip body 30 is prevented from dropping off from the drill body 10 with certainty.

Further, instead of forming the inclined portion 37 in the region located between the ridge lines of the convex portions 36..., The inclined portion 37 is formed in the region located in the ridge line of the convex portions 36. The region located between the pair of outer surfaces 34 may be substantially parallel to each other, and the region received by the chip mounting seat 14 in the chip body 30 is not formed with the convex portions 36. While being a substantially flat surface, the outer surface 34 itself, which is a substantially flat region, may be the inclined portion 37.
In addition, the inclined portion 37 does not need to be formed over the entire region of the chip body 30 that is received by the chip mounting seat 14, and may be formed only in a partial region on the tip side, for example. .

Moreover, in this embodiment, it is not a chip | tip as shown in FIGS. 6-8, for example, as shown in FIG. 14, about the cutting blades 35 and 35 formed in the front-end | tip of the chip | tip main body 30, the outer peripheral end is included. You may use the chip | tip used as the finishing blades 35B and 35B which made a part reverse | retreat to the rear-end side of the axis line O direction by the predetermined space | interval. Specifically, the length d along the radial direction of the drill body 10 in the finishing blade 35B is set in a range of 0.01 mm to 0.10 mm, and the rear end surface of the tip body 30 at the outer peripheral end of the finishing blade 35B. The distance along the axis O direction from 32 is set to about a / 3 with respect to the distance a along the axis O direction from the rear end face 32 of the tip body 30 at the outer peripheral end of the cutting blade 35 excluding the finishing blade 35B. Has been.
In drilling using a throw-away drill in which the tip shown in FIG. 14 is mounted on the tip mounting seat 14, a machining hole is formed in the workpiece by the main cutting blades 35, 35 located at the tip of the tip body 30. Since the inner wall surface of the machining hole can be finished by the finishing blades 35B and 35B that are retracted to the rear end side by one stage from the cutting blades 35 and 35, the inner wall surface of the machining hole to be formed The accuracy can be improved.

It is a side view of the throw away type drill of the embodiment of the present invention. It is a tip end view of the throw away type drill of an embodiment of the present invention. It is an A direction arrow directional view in FIG. FIG. 2 is a partial cross-sectional view taken in the direction of arrow A in FIG. 1. It is the BB sectional view taken on the line in FIG. It is a side view of the chip | tip with which the throwaway type drill of embodiment of this invention is mounted | worn. It is a tip end view of a tip with which a throw away type drill of an embodiment of the present invention is attached. It is a C direction arrow partial sectional view in FIG. It is principal part expansion explanatory drawing which shows the modification of the slit in the throw-away type drill of embodiment of this invention. It is a front view which shows the modification of the throw-away type drill of embodiment of this invention. It is sectional drawing which shows the modification of the throw-away type drill of embodiment of this invention. It is sectional drawing which shows the modification of the throw-away type drill of embodiment of this invention. It is principal part expansion explanatory drawing which shows the modification of the throw-away type drill of embodiment of this invention. It is a side view which shows the modification of the chip | tip with which the throwaway type drill of embodiment of this invention is mounted | worn. It is a front end view of a conventional throw-away drill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drill main body 11 Front end surface 12 Chip discharge groove 14 Tip mounting seat 14A Bottom surface 14B Inner side surface 13 Front end portion 13A First front end portion 13B Second front end portion 15 Guide groove 17 Slit 20 Insertion hole 30 Tip main body 31 Front end surface 34 Outer side surface 34A Rake face 35 Cutting edge 36 Convex part 37 Inclined part 40 Clamp bolt 41 Head part 42 Shaft part 50 Concave part 51 Press part L Center line of clamp bolt (extending direction of insertion hole)
O axis T Drill rotation direction

Claims (7)

A pair of chip discharge grooves are formed on the outer periphery of the drill body rotated about the axis, and are formed in a concave groove shape that communicates with the pair of chip discharge grooves at the tip of the drill body and opens at the tip surface of the drill body. A tip mounting seat is formed, and the tip mounting seat has a throwaway tip having a substantially flat tip body with a pair of cutting blades formed at the tip thereof, and the pair of outer side surfaces of the tip body are connected to the tip. A state in which a pair of rake faces which are portions facing the front side in the drill rotation direction on the pair of outer surfaces of the tip body are opened in the pair of chip discharge grooves, respectively, while being opposed to the pair of inner side surfaces of the mounting seat. Thus, the pair of inner side surfaces of the tip mounting seat can be brought close to each other with a clamp bolt screwed into the tip of the drill body so as to intersect the tip mounting seat. By a indexable drill which is mounted fixed,
The inner surface of the tip mounting seat is formed with a recess that does not contact the outer surface of the tip body, so that it is adjacent to the recess so as to be located behind the center line of the clamp bolt in the drill rotation direction. Then, when the clamp bolt is screwed in, there remains a pressing portion that presses the outer surface of the tip body so as to rotate the tip body about the axis toward the rear side in the drill rotation direction. Characteristic throw-away type drill. The throw-away drill according to claim 1,
A guide groove extending along the axial direction is formed in a portion facing the front side in the drill rotation direction on the inner side surface of the tip mounting seat, and a portion facing the rear side in the drill rotation direction on the outer surface of the tip body. A throw-away drill characterized in that a convex portion engageable with the guide groove is formed, and the guide groove and the convex portion are engaged with each other. The throw-away drill according to claim 1 or 2,
The throw-away drill characterized in that an inclined portion that projects outward in the thickness direction from the front end side toward the rear end side is formed in an area of the chip body that is received by the chip mounting seat. The throw-away drill according to claim 3,
A guide groove extending along the axial direction is formed in a portion facing the front side in the drill rotation direction on the inner side surface of the tip mounting seat,
A convex portion that can be engaged with the guide groove is formed on a portion of the outer surface of the tip body facing the rear side in the drill rotation direction, and the inclined portion is formed in a region located between ridge lines of the convex portions. Formed,
The throw-away drill characterized in that the guide groove and the convex portion are engaged with each other, whereby the inclined portion and the region located between the bottom portions of the guide groove are engaged with each other. The throw-away drill according to claim 3 or 4,
The throw-away drill characterized in that the slope of the inclined portion is 0 ° 01 'to 3 °. The throw-away drill according to any one of claims 1 to 5,
A slit extending toward the rear end side in the axial direction is cut in the bottom surface facing the tip end side in the axial direction in the chip mounting seat,
When viewed from the tip end side in the axial direction, the clamp bolt is more than the one pressed by the head of the clamp bolt among the tip ends of the drill body divided into two by the tip mounting seat. A throw-away drill characterized in that the shaft portion of the shaft is displaced so as to approach the other screwed-in portion. The throw-away drill according to claim 6,
A throw characterized in that the crossing angle between the extending direction of the slit and the extending direction of the clamp bolt when viewed from the front end side in the axial direction is set in a range of 90 ° ± 15 °. Away drill.

Images