JP2007136563A - Insert type drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert type drill capable of forming a machined hole with good accuracy by holding down run-out of the drill even in the case of machining a deep hole. <P>SOLUTION: In this insert type drill 1, an insert 20 having a cutting blade 22 is removably mounted on an insert mounting eye 5 formed at the tip part 4 of a drill body 2. The drill body 2 is provided with a chip discharge groove 3 formed extending from the tip part of the drill body 2 toward the rear end of the drill body 2, and an outer peripheral guide part 8 is provided on the rear side in the drill rotating direction T of the chip discharge groove 3 at the tip part of the drill body 2. The outer peripheral guide part 8 includes: a first pad part 9 located ahead in the drill rotating direction T; a second pad part 11 located backward in the drill rotating direction T; and a recess part 10 located between the first pad part 9 and the second pad part 11 and recessed inward in the radial direction of the drill body 2. The drill body 2 is provided with a cutting oil supply hole 13 opened to the recess part 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an insert type drill in which an insert having a cutting edge at its tip is detachably attached to the tip side of a drill body.

  Conventionally, as a cutting tool for drilling a material to be cut, an insert-type drill having a tip body insert mounting seat is formed, and an insert having a cutting edge at the tip is detachably mounted on the insert mounting seat. Is used. In such an insert-type drill, when the cutting blade is worn out by cutting the workpiece, only the insert can be replaced and used, and the cost of using the drill can be reduced.

  A conventional insert-type drill has a drill body having a substantially cylindrical shape rotated about an axis, and an insert mounting seat having a groove shape recessed toward the rear end side of the drill body at the tip of the drill body. The insert mounting seat is mounted with an insert having a cutting blade to constitute a drill (see Patent Document 1 and Patent Document 2).

  In this type of insert-type drill, on the insert mounting seat of the drill body, a bottom surface that faces the tip side and is perpendicular to the axis of the drill body, and an axis line that crosses the bottom surface and faces the inside of the drill body in the radial direction. A pair of clamp surfaces are formed so as to be opposed to each other and sandwich the insert. The insert mounting seat includes a clamp screw for elastically deforming the pair of clamp surfaces so as to approach each other.

The insert mounted on the insert mounting seat is made of a hard material such as cemented carbide, has a substantially pentagonal flat plate shape, and a pressed surface on which a part of the pentagonal surface is pressed against the clamp surface. It is said that. In this insert, when the insert is mounted on the insert mounting seat, a portion of the pentagonal surface facing the front side in the drill rotation direction is a rake face, and the ridge line portion between the rake face and the tip end face of the insert is defined as a rake face. A cutting edge is formed.
And the margin part which protruded toward the outer peripheral side is formed in the outer peripheral surface of an insert so that it may continue in a drill rotation direction back side from the intersection ridgeline of this outer peripheral surface and a rake face.

The insert type drill configured as described above is rotated around the axis O and fed in the direction of the axis O to perform cutting so as to form a processed hole in the workpiece. Here, when the margin portion slides on the inner wall surface of the machining hole formed in the workpiece, the rotation of the drill is stabilized and the machining hole can be formed with high accuracy.
JP 2005-169572 A JP 2004-330391 A

  By the way, when an insert type drill having this configuration is used to form a deep hole, for example, a deep hole having a hole depth L of L / D = 5 or more with respect to the outer diameter D of the drill, Since the drill is deformed to bend due to the cutting resistance and the drill is shaken, the processed hole cannot be accurately formed. In order to prevent the deflection due to the deformation of the drill, there is a processing method in which a pilot hole is formed in advance in a workpiece and an insert type drill is inserted into the pilot hole. By processing in this way, the deformation of the drill is suppressed by the prepared hole, so that the processed hole can be formed with high accuracy.

  However, even in the above-described processing method, when the cutting blade bites immediately after the insert-type drill is inserted into the pilot hole, the drill may swing greatly. Also, since the margin that slides with the inner wall surface of the pilot hole is formed only at the insert part at the tip of the drill, especially when the drill swings to the side without the margin, the rotation of the drill must be sufficiently stabilized. There is a problem that the processed hole cannot be formed with high accuracy.

  The present invention has been made in view of the above-described circumstances, and is an insert type drill that can form a drilled hole with high accuracy while suppressing drill runout even when processing a deep hole. The purpose is to provide.

  In order to solve the above-mentioned problems, according to the present invention, an insert mounting seat is formed at the tip of a drill body rotated about an axis, and an insert having a cutting edge at the tip is detachably mounted on the insert mounting seat. An insert-type drill, wherein the drill body has a chip discharge groove extending from the drill body front end side toward the drill body rear end side, and the chip discharge groove on the drill body front end side in the drill rotation direction Is provided with a first pad portion located on the front side in the drill rotation direction, a second pad portion located on the rear side in the drill rotation direction, and the first pad portion. A relief portion that is located between the pad portion and the second pad portion and is recessed inward in the radial direction of the drill body is provided, and the drill body is provided with a cutting oil supply hole that opens to the relief portion. Have It is characterized in that.

According to this insert type drill, since the outer peripheral guide part provided with the first and second pad parts spaced apart in the circumferential direction via the relief part is formed on the tip side of the drill body, the inner peripheral surface of the pilot hole As the first and second pad portions of the outer peripheral guide portion slide, the rotation of the drill can be stabilized to prevent the drill from swinging, and the processed hole can be formed with high accuracy.
In addition, a relief portion that is recessed radially inward is formed in the outer periphery guide portion, and a cutting oil supply hole is opened in the escape portion, so that the outer periphery guide portion is supplied by supplying cutting oil from the cutting oil supply hole. And the inner wall surface of the pilot hole can be well lubricated, and seizure of the outer peripheral guide portion can be prevented.

  Here, the outer peripheral guide portion is formed so as to extend from the front end surface of the drill main body toward the rear end side of the drill main body, and the axial length of the outer peripheral guide portion is set with respect to the drill outer diameter D. By making it within the range of 1 × D to 5 × D, the length of the outer peripheral guide portion sliding with the inner wall surface of the pilot hole can be secured, and the rotation of the drill can be reliably stabilized, Since there is no portion sliding with the inner wall surface of the pilot hole more than necessary, cutting resistance can be suppressed.

  Furthermore, by forming the bottom surface of the relief portion into a convex curved surface that is convex outward in the radial direction of the drill body, the portion that cuts out the drill body is reduced, and the rigidity of the drill body can be ensured.

  Further, by configuring the length L of the chip discharge groove in the axial direction to be L / D = 5 or more with respect to the drill outer diameter D, the insert type drill can be made up to the machining hole length L. Can be used for machining of deep holes.

  As described above, according to the present invention, it is possible to provide an insert-type drill capable of forming a drilled hole with high accuracy while suppressing drill runout even when processing a deep hole.

Hereinafter, an insert type drill according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 to 4 show an insert type drill according to an embodiment of the present invention.
The insert type drill 1 includes a drill body 2 that is rotated around an axis O to form a substantially cylindrical shape, and an insert 20 that is detachably attached to the distal end side of the drill body 2.

  On the outer periphery of the drill body 2, a pair of chip discharge grooves 3 that open to the front end surface of the drill body 2 and extend toward the rear end side of the drill body 2 are formed 180 ° rotationally symmetrical with the axis O interposed therebetween. The tip side portion of the chip discharge groove 3 is formed to be twisted toward the rear side of the drill rotation direction T as it goes toward the rear end side of the drill body 2. It is formed to extend in parallel with O.

In addition, a groove-shaped insert mounting seat 5 that opens at the distal end surface of the drill body 2 and is recessed toward the rear end side of the drill body 2 extends in the diameter direction passing through the axis O at the distal end portion 4 of the drill body 2. It is formed as follows.
The insert mounting seat 5 is directed to the front end side in the direction of the axis O and perpendicular to the axis O, and is erected from the bottom surface, and is parallel to each other and parallel to the axis O and intersects the front end surface of the drill body 2. A clamp surface 5A is provided, and is configured to open in a “U” shape toward the distal end surface of the drill body 2 in a side view along the bottom surface and the clamp surface 5A.

  More specifically, the insert mounting seat 5 is notched in the diametrical direction passing through the axis O between the wall surfaces facing the front side of the drill rotation direction T on the distal end side of the chip discharge groove 3 at the distal end portion 4 of the drill body 2. In both ends of the extending direction M, the chip discharge grooves 3 are communicated with each other.

  Further, the insert mounting seat 5 having such a concave groove shape is formed at the distal end portion 4 of the drill body 2, so that the distal end portion 4 of the drill body 2 has a first distal end portion 4A and a second distal end portion 4B. The bottom surface of the insert mounting seat 5 is positioned between the first tip portion 4A and the second tip portion 4B, and the insert mounting seat is located on the first tip portion 4A side. 5, one of the pair of clamp surfaces 5A is positioned, and the other of the pair of clamp surfaces 5A is positioned on the second tip portion 4B side.

  Here, a thinning surface of the insert 20 to be described later is formed on the tip surface of the drill body 2 so that a cross ridge line portion between the tip surface and a wall surface facing the rear side in the drill rotation direction T in the chip discharge groove 3 is cut out. 25, a body-side thinning surface 6 is formed, and a pair of clamp surfaces 5A in the insert mounting seat 5 that intersects the distal end surface of the drill body 2 are formed so as to also intersect these body-side thinning surfaces 6. ing.

  A plurality of guide grooves 7 extending along the axis O direction are formed in each of the pair of clamp surfaces 5A in the insert mounting seat 5 so as to be arranged at predetermined intervals in a direction orthogonal to the axis O. Here, in each of the pair of clamp surfaces 5A, the guide groove 7 is formed in a portion (a portion where the front end side intersects the main body side thinning surface 6) connected to the rear end side of the main body side thinning surface 6 in the axis O direction. It is not formed and is formed in a planar shape.

  When the drill body 2 is viewed from the front end side in the direction of the axis O, as shown in FIG. 2, the intersecting ridge lines between the pair of clamp surfaces 5A and the body-side thinning surface 6 are each linear, and The intersecting ridge line portion between the pair of clamp surfaces 5A and the tip surface excluding the main body side thinning surface 6 is formed into a wave shape by the plurality of guide grooves 7 respectively.

  Further, an insertion hole for screwing a clamp screw 30 to be described later is formed in the distal end portion 4 of the drill body 2. This insertion hole is formed so as to extend in the L direction shown in FIG. 2, that is, to extend in the diametrical direction passing through the axis O and intersecting the insert mounting seat 5, and to penetrate the distal end portion 4. The side end portions are opened on the outer peripheral surface of the first tip portion 4A and the outer peripheral surface of the second tip portion 4B, respectively.

  The insertion hole is formed so as to extend in the diameter direction passing through the axis O as in the case of the insert mounting seat 5, and the extending direction L is shown in FIG. 2 when viewed from the front end side in the axis O direction. Thus, it is configured not to be parallel to the width direction N of the insert mounting seat 5 which is a direction orthogonal to the extending direction M of the insert mounting seat 5 but to be inclined with respect to the width direction N of the insert mounting seat 5. Yes.

Moreover, the outer peripheral guide part 8 is formed in the outer peripheral surface connected to the drill rotation direction T back side of each chip | tip discharge groove | channel 3 in the front end side part of this drill main body 2, and as shown in FIG. The outer peripheral guide portion 8 is disposed 180 degrees rotationally symmetrical about the axis O.
The outer peripheral guide portion 8 is disposed at a portion connected to the outer peripheral end of the chip discharge groove 3 and protrudes toward the radially outer side of the drill body 2, and the drill rotation direction T of the first pad portion 9. Consists of a relief portion 10 that is continuous with the rear side and is recessed inward in the radial direction of the drill body 2, and a second pad portion 11 that is continuous with the rear side of the drill rotation direction T and protrudes outward in the radial direction of the drill body 2. Has been.

Each of the first pad portion 9 and the second pad portion 11 has a cross section perpendicular to the axis O formed in an arc shape centered on the axis O, and the arc formed by the first pad portion 9 and the second pad portion 11. Are equal to each other, and in the present embodiment, the lengths of the arcs are also equal to each other.
Further, the relief portion 10 is formed in an arc shape that is convex outward in the radial direction, and the radius of the arc formed by the relief portion 10 is the arc shape formed by the first pad portion 9 and the second pad portion 11. The length of the arc is made smaller than the radius, and the length of the arc is made larger than the length of the arc formed by the first pad portion 9 and the second pad portion 11, whereby the first pad portion 9 and the second pad portion 11 are , And are arranged so as to form an included angle of about 90 ° with the axis O as the center.

  In this embodiment, as shown in FIG. 3, two first pad portions 9 and two second pad portions 11 are provided, and four pad portions are provided as a whole. The pair of first pad portions 9 is disposed 180 degrees rotationally symmetrical about the axis O, and the pair of second pad portions 11 is also disposed 180 degrees rotationally symmetrical about the axis O. Accordingly, a total of four first and second pad portions 9 and 11 are arranged at approximately equal intervals in the circumferential direction.

  As shown in FIG. 1, the outer peripheral guide portion 8 is formed so as to be twisted toward the rear side of the drill rotation direction T as it goes toward the rear end side of the drill body 2, similarly to the tip side portion of the chip discharge groove 3. The first pad portion 9, the second pad portion 11, and the relief portion 10 are also twisted toward the rear side in the drill rotation direction T at the same twist angle as the tip side portion of the chip discharge groove 3 as it goes toward the rear end side of the drill body 2. Is formed.

  The outer peripheral guide portion 8 is provided from the front end surface of the drill body 2 toward the rear end side of the drill body 2, and the length C in the direction of the axis O is 1 × D to 5 × with respect to the drill outer diameter D. In this embodiment, C is set to about 2 × D. The outer peripheral surface of the drill body 2 connected to the rear side in the drill rotation direction T of the chip discharge groove 3 extending in parallel to the axis O on the rear end side further than this is one step higher than the radius of the first and second pad portions 9 and 11. It is formed in a circular arc shape with a small radius.

As shown in FIGS. 1 and 4, the drill main body 2 has a pair of cutting oil holes 12 that open to the rear end surface of the drill main body 2 and extend parallel to the axis O, in the portion where the outer peripheral guide portion 8 is provided. The drill body 2 is drilled to reach the rear end side.
As shown in FIGS. 1 and 2, the drill body 2 has a cutting oil supply hole 13 that communicates with the cutting oil hole 12 and extends obliquely toward the distal end side of the drill body 2 and the radially outer side of the drill body 2. As shown in FIGS. 1 and 3, one end of the cutting oil supply hole 13 is opened in the escape portion 10 of the outer peripheral guide portion 8.

  Next, the insert 20 mounted on the insert mounting seat 5 will be described. The insert 20 is made of a hard material such as a cemented carbide, and its outer shape is substantially a pentagonal flat plate. In this insert 20, a portion from the center portion of the pentagonal surface 21 to the rear end surface is cut out so as to cross obliquely with respect to the thickness direction of the insert 20. The part is formed.

When the insert 20 is mounted on the insert mounting seat 5, a portion of the pentagonal surface 21 of the insert 20 that faces the front side of the drill rotation direction T serves as a rake face 21A, and a portion that faces the rear side of the drill rotation direction T The pressed surface 21B is in contact with the clamp surface 5A of the insert mounting seat 5. That is, the pentagonal surface 21 of the insert 20 is formed with a notch in the central portion disposed in the vicinity of the axis O, and the scoop surface 21A and the pressed surface 21B are provided across the notch. is there.
The rake face 21 </ b> A has a concave curved shape in which the central portion in the width direction is recessed toward the rear side of the drill rotation direction T, and is formed so as to gradually twist toward the rear side of the drill rotation direction T toward the rear end side. Has been.

  The distal end surface of the insert 20 is formed in an isosceles triangle shape that gradually recedes from the axis O toward the outer peripheral side in a state where the insert 20 is mounted on the insert mounting seat 5. A cutting edge 22 is formed at each intersection ridge line portion between the rake face 21A and the rake face 21A. When the cutting edge 22 is viewed from the front end surface side, the rake face 21A is formed in a concave curved surface shape, so that the cutting blade 22 has a concave curved shape recessed in the drill rotation direction T rear side. Here, the radius around the axis O of the cutting edge 22 is slightly larger than the radius of the first and second pad portions 9 and 11.

  Further, the tip surface of the insert 20 has a multi-step surface shape composed of a first flank 23 continuous to the cutting edge 22 and a second flank 24 continuous to the rear side of the first flank 23 in the drill rotation direction T. I am doing. For this reason, the cutting edge 22 is provided with a relief that increases in a multistage manner as it goes rearward in the drill rotation direction T.

On the tip side of each rake face 21A, in the state where the insert 20 is mounted, the axis O located at the center of the tip face of the insert 20 from the vicinity where the rake face 21A and the other part of the pentagonal face 21 of the insert 20 intersect. The front end surface is formed so that the region up to the adjacent position is notched obliquely toward the front side of the drill rotation direction T toward the front end side in the direction of the axis O, so as to be continuous with the inner peripheral end side of the cutting blade 22. A thinning surface 25 is formed so as to extend toward the axis O located at the center of the front end surface so as to reach the portion of the pentagonal surface 21 other than the rake face 21A.
Thereby, the thinning cutting edge 26 which makes | forms the substantially linear shape extended toward the axis line O located in the center of a front end surface is arrange | positioned at the part of the inner peripheral end side of the cutting edge 22. FIG.

  Further, on the pressed surface 21 </ b> B formed on the pentagonal surface 21, a plurality of convex portions 27 extending along the axis O direction are arranged at predetermined intervals in a direction orthogonal to the axis O when the insert 20 is mounted. Is formed. In each pressed surface 21 </ b> B, a portion connected to the rear end side of the thinning surface 25 (a portion where the front end side intersects the thinning surface 25) is formed in a flat shape without the convex portion 27 being formed.

  Further, each of the pair of outer peripheral surfaces facing the outer peripheral side of the insert 20 has a margin portion 28 having an arc shape with the axis O as the center, with the front side of the drill rotation direction T intersecting the outer peripheral side ridge portion of the rake face 21A. And a marginal surface 29 that is continuous to the rear side of the drill rotation direction T and has a second surface 29 having a circular arc shape having a radius smaller than that of the circular arc formed by the margin portion 28.

  In the insert 20 having such a configuration, the thickness direction of the insert 20 is set in the diametrical direction in which the insert mounting seat 5 extends with respect to the insert mounting seat 5 having a concave groove shape formed in the distal end portion 4 of the drill body 2. In a state where they are orthogonal, they are inserted by being slid toward the rear end side in the direction of the axis O. At this time, the guide groove 7 formed on the clamp surface 5A of the insert mounting seat 5 and the convex portion 27 formed on the pressed surface 21B of the insert 20 are engaged and inserted.

  As a result, the rear end surface of the insert 20 is disposed opposite to the bottom surface of the insert mounting seat 5 and brought into close contact with each other, and the rake face 21A of the insert 20 is opened into the chip discharge groove 3 and drill rotation direction T A guide surface formed on the clamp surface 5A and a convex portion 27 formed on the pressed surface 21B, with the pressed surface 21B of the insert 20 facing the clamp surface 5A of the insert mounting seat 5 while being directed to the front side. The grooves 7 are engaged with each other.

  At this time, a portion (a portion where the front end side intersects with the thinning surface 25) connected to the rear end side of the thinning surface 25 formed in the insert 20 in a flat shape is the clamp surface 5 </ b> A of the insert mounting seat 5. A portion that is formed in a planar shape connected to the rear end side of the main body side thinning surface 6 (a portion where the front end side intersects with the main body side thinning surface 6) is disposed opposite to each other, and the front end side of the portions formed in the flat shape The thinning surface 25 and the main body side thinning surface 6 are continuously connected to each other.

Next, the clamp screw 30 is screwed into the insertion hole provided on the distal end side of the drill body 2 so as to penetrate the notch portion of the insert 20 inserted in the insert mounting seat 5.
Thereby, the front-end | tip part 4 of the drill main body 2 is elastically deformed so that a pair of clamp surface 5A of the insert mounting seat 5 may mutually approach, and these pair of clamp surfaces 5A strengthen the to-be-pressed surface 21B of the insert 20. The projecting portion 27 and the guide groove 7 that are engaged with each other are firmly brought into close contact with each other, and the insert 20 is mounted on the insert mounting seat 5. Here, the length L of the chip discharge groove 3 in the axis O direction from the drill tip side is configured so that L / D = 5 or more with respect to the outer diameter D of the drill.

The insert type drill 1 having such a configuration is rotated around the axis O and fed in the direction of the axis O to perform cutting so as to form a processed hole in the workpiece. .
In this insert type drill 1, the length L in the axis O direction from the tip end side of the chip discharge groove 3 is configured to be L / D = 5 or more with respect to the outer diameter D of the drill. It can be used for deep hole machining such that the length of the hole is the length L of the chip discharge groove 3. When forming such a deep hole, a pilot hole is formed in advance in the material to be cut, and the insert drill 1 is inserted into the pilot hole to perform drilling.

According to the insert type drill 1 according to the present embodiment, since the outer peripheral guide portion 8 is formed on the tip side of the drill body 2, the inner peripheral surface of the pilot hole and the outer peripheral guide portion 8 slide, The rotation of the drill can be stabilized, and the processed hole can be formed with high accuracy.
Further, the outer peripheral guide portion 8 is formed with a relief portion 10 that is recessed inward in the radial direction of the drill body 2, and the cutting oil supply hole 13 is opened in the relief portion 10, so that the cutting oil is supplied from the cutting oil supply hole 13. By discharging, cutting oil is supplied between the outer periphery guide portion 8 and the inner wall surface of the pilot hole, and seizure of the outer periphery guide portion 8 can be prevented.

  Moreover, since the cutting oil supply hole 13 is opened so as to incline toward the tip end side of the drill body 2, the cutting oil is also supplied toward the drill tip side, and the cutting with the cutting edge 22 is smoothly performed. And the discharge of chips can be promoted.

  Further, the outer peripheral guide portion 8 is formed from the front end surface of the drill body 2 toward the rear end side, and the axial length C thereof is set within a range of 1 × D to 5 × D with respect to the drill outer diameter D. In the present embodiment, the length is about 2 × D. Therefore, the length of the outer peripheral guide portion 8 that slides with the inner wall surface of the pilot hole is secured, and the insert-type drill 1 is reliably rotated. In addition to being stable, there is no portion sliding with the inner wall surface of the pilot hole more than necessary, and cutting resistance can be suppressed.

  Furthermore, since the escape portion 10 is formed in a convex curved surface that is convex outward in the radial direction of the drill body 2, the portion of the drill body 2 that is notched in order to form the escape portion 10 can be reduced. The rigidity of the drill body 2 can be ensured.

  Further, the outer peripheral guide portion 8 is formed to be twisted to the rear side of the drill rotation direction T as it goes to the rear end side of the drill body 2, and the first pad portion 9 and the second pad portion 11 are also formed on the rear end side of the drill body 2. Since it is formed so as to be twisted to the rear side in the drill rotation direction T as it goes to the direction, the impact when the first pad portion 9 and the second pad portion 11 collide with the inner wall surface of the prepared hole can be kept small. This can prevent the drill from swinging.

The insert drill according to the embodiment of the present invention has been described above. However, the present invention is not limited to this embodiment, and can be appropriately changed without departing from the technical idea of the present invention.
For example, the outer peripheral guide portion formed on the drill body has been described as having the first pad portion and the second pad portion formed thereon, but the present invention is not limited to this, and three or more pad portions are formed. May be.

Moreover, although it demonstrated by what formed two cutting oil holes extended in parallel with the axis O, it is not limited to this, For example, what formed one cutting oil hole so that it may extend along the axis O It may be.
Furthermore, although the chip discharge groove has been described as being formed so as to extend parallel to the axis O on the drill body rear end side, the drill body rear end side also has a drill rotation direction T rearward side toward the rear end side. You may form so that it may twist.

It is a side view of an insert type drill which is an embodiment of the present invention. It is a X direction arrow line view in FIG. It is YY sectional drawing in FIG. It is ZZ sectional drawing in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert type drill 2 Drill main body 3 Chip discharge groove 5 Insert mounting seat 8 Outer periphery guide part 9 1st pad part 10 Escape part 11 2nd pad part 13 Cutting oil supply hole 20 Insert 22 Cutting edge

Claims (4)

An insert-type drill in which an insert mounting seat is formed at the tip of a drill body rotated about an axis, and an insert having a cutting edge at the tip is detachably attached to the insert mounting seat,
The drill body is formed with a chip discharge groove extending from the drill body front end side toward the drill body rear end side, and an outer peripheral guide portion is provided on the drill rotation direction rear side of the chip discharge groove on the drill body front end side. And
The outer periphery guide portion includes a first pad portion located on the front side in the drill rotation direction, a second pad portion located on the rear side in the drill rotation direction, and a position between the first pad portion and the second pad portion. An insert type drill having a relief portion recessed inwardly in the radial direction of the drill body, wherein the drill body is provided with a cutting oil supply hole that opens to the relief portion.   The outer peripheral guide portion is formed so as to extend from the front end surface of the drill main body toward the drill main body rear end side, and the length in the axial direction of the outer peripheral guide portion is relative to the drill outer diameter D. The insert type drill according to claim 1, wherein the insert type drill is in a range of 1xD to 5xD.   The insert type drill according to claim 1 or 2, wherein the relief portion is formed in a convex curved shape that is convex toward the radially outer side of the drill body.   The length L of the said axial direction of the said chip discharge groove is set to L / D = 5 or more with respect to the drill outer diameter D, The Claim 1 characterized by the above-mentioned. Insert type drill.

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