JP4144866B2 - Throw-away drilling tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a throw-away type drilling tool (hereinafter referred to as a drilling tool) for mounting a throw-away tip (hereinafter referred to as a chip).
[0002]
[Prior art]
In some conventional drilling tools, the bottom blade is composed of an outer peripheral blade and a center blade. It shows a first conventional drilling tool of this type in FIGS. 8 and (a) (b) is a rear view the tip front view of the drilling tool respectively, FIG. 9 is the rotation locus of the rotary axis O of the peripheral cutting edge and the center cutting edge of the drilling tool shown in FIG. 8 It is.
[0003]
As shown in FIG. 8 , in the first conventional drilling tool, the tool body 1 has a rod shape, and a handle (not shown) is provided at the rear end in the rotational axis O direction, and from the front end to the rear end. On the other hand, the first flute groove 3 and the second flute groove 4 are formed at substantially symmetrical positions with respect to the axis center P. A tip seat 5 is formed in the first and second flute grooves 3 and 4, and the tip 7 used as the center blade 7 </ b> A and the outer peripheral blade 7 </ b> B uses the center mounting hole 8 in the tip seat 5. Then, it is fixed by screws 9.
[0004]
As shown in FIGS. 8 and 9 , the tip 7 is a positive type tip 7 having a substantially parallelogram flat plate shape, and is also used as the center blade 7 </ b> A and the outer peripheral blade 7 </ b> B. The tip 7 has two opposite rotationally symmetric ends, and one of the opposite ends in the longitudinal direction is formed by a long side edge cutting edge 7a and a short side corner cutting edge 7b. The other opposing end is formed by a long side edge ridge cutting edge 7c and a short side corner cutting edge 7d. The side edge cutting edges 7a and 7c and the corner edge cutting edges 7b and 7d form a V-shaped cutting edge ridge line where obtuse angles intersect. A corner blade 11 is formed at the intersection of the adjacent corner portion cutting edges 7b and 7d.
[0005]
The center edge 7A has a long edge ridge edge 7c and a short edge corner edge 7d located adjacent to the edge ridge edge 7c on the inner peripheral side as a bottom edge, and the outer edge 7B is The long edge ridge cutting edge 7a and the short edge corner cutting edge 7b located on the outer peripheral side adjacent to the edge ridge cutting edge 7a are the bottom edges. The corner cutting edge 7d adjacent to the corner cutting edge 7b, which is the bottom cutting edge, via the corner blade 11 is inclined at an angle of relief angle に 対 し て with respect to the rotation axis O of the tool body so as to function as a back taper. It is arranged. Further, the central edge 7A and the outer peripheral edge 7B are arranged so that the side ridge part cutting edge 7c and the side ridge part cutting edge 7a intersect each other in a rotation locus on a plane including the rotation axis O of the drilling tool. At the point S that is provided and intersects, the tip 7 is incorporated so that the cutting width by the outer peripheral blade 7B is shorter than the cutting width by the central blade 7A.
[0006]
In the drilling tool having such a configuration, the center blade 7A cuts the inner peripheral side from the intersecting point S, and the outer peripheral blade 7B cuts the outer peripheral side from the point S to drill. And the inner wall of the hole which only the corner blade 11 of the said outer periphery blade 7B perforates is cut. (For example, see Patent Document 1)
[0007]
In addition, as a second conventional drilling tool of this type, there is a tool provided with a guide pad in order to ensure high straightness particularly when a machining hole is pulled out. The drilling tool shown in FIGS. 10 and 11. FIG. 10 is a front view of the tip of the drilling tool, and FIG. 11 is a side view of the drilling tool when viewed from the tip. In this conventional drilling tool, the tool body 1 has a substantially multi-stage cylindrical shape with the rotation axis O as the center, and a rear end portion of the tool body 1 via a flange portion (not shown) formed in a bowl shape. A shank portion (not shown) for gripping the main body 1 on the spindle of the machine tool is formed, and an outer peripheral portion on the front end side of the flange portion is formed on the front end surface of the tool main body 1 from the front end surface of the flange portion. The pair of flute grooves 3 and 4 that spirally twist around the rotation axis O toward the rear side in the rotation direction K of the tool body 1 toward the rear end side are on opposite sides of the rotation axis O. In particular, the flute grooves 3 and 4 are formed such that a cross section perpendicular to the rotation axis O is substantially L-shaped at the tip portion 15 of the tool body 1.
[0008]
Further, in the tip portion 15 of the tool body 1, the tip inner peripheral portion 15 </ b> A on the inner peripheral side protrudes from the tip outer peripheral portion 15 </ b> B on the outer peripheral side to the one-step tip side, and the rotation axis O is the center. The flute grooves 3 and 4 are formed so that the depth of the flute grooves 3 and 4 reaches the inner peripheral portion 15A of the tip. Further, tip seats 5 are formed at the respective tip portions of the tip inner peripheral portion 15A and the tip outer peripheral portion 15B of the wall surfaces of the flute grooves 3 and 4 facing the tool rotation direction K side. The chip 7 is detachably attached by screws 9 with its cutting edges 7a, 7b, 7c, 7d slightly protruding from the tip surface of the tool body 1 at the tip inner peripheral portion 15A and the tip outer peripheral portion 15B. Yes. These chips 7 are formed of a hard material such as cemented carbide in a substantially rhombic flat shape of the same shape and size, and one of the rhombus surfaces is a rake face, The four edge portions are respectively formed with the cutting edges 7a, 7b, 7c, 7d that are bent at an obtuse angle and are convex outward, and the cutting edge 7a is positioned so that the bending point is located at the forefront. , 7b, 7c, 7d are attached to the tip seat 5 with the tip side facing.
[0009]
In both the tip inner peripheral portion 15A and the tip outer peripheral portion 15B, the tip 7 attached to the tip seat 5 formed in one flute groove 3 has its side edge cutting edges 7c and 7d biased toward the inner peripheral side. On the other hand, the side ridge part cutting edges 7a and 7b of the tip 7 attached to the tip seat 5 of the other flute groove 4 are arranged to be biased toward the outer peripheral side, and these side ridge part cutting edges 7a. , 7b, 7c, and 7d are configured such that the rotation locus around the rotation axis O is continuous in the radial direction with respect to the rotation axis O. Note that the side edge ridges 7c and 7d of the center blade 7A attached to the tip inner periphery 15A of the one flute groove 3 located on the innermost innermost side are such that the inner periphery exceeds the rotation axis O and the other Of the outer peripheral edge 7B of the outer peripheral edge 7B attached to the outer peripheral edge 15B of the other outermost flute groove 4 so as to be slightly over-centered on the flute groove 4 side of The outer diameter is the outer diameter D of this drilling tool. Further, on the outer peripheral surface of the tool body 1, a pair of concave grooves 20 are formed on the rotation axis O on opposite sides of the rotation axis O at a substantially central portion between the pair of flute grooves 3, 4 in the circumferential direction. The guide grooves 21 made of brass are detachably attached to these concave grooves 20 by pad set screws 22, and the outer peripheral surfaces of these guide pads 21 are the tips of the tool body 1. It protrudes slightly from the outer peripheral surface of the part, and forms an arc surface centering on the rotation axis O with an outer diameter slightly smaller than the outer diameter D. In the direction of the rotational axis O, the concave groove 20 spirally forms with the concave groove 20 extending in parallel to the rotational axis O from a position slightly retracted from the distal end surface of the tool body 1 at the distal end outer peripheral portion 15B. The twisted flute grooves 3 and 4 are formed until just before crossing, and therefore, the guide pad 21 is also disposed only within the range of the tip end side of the tool body 1 in the rotation axis O direction. (For example, see Patent Document 2)
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-029108 (pages 3 to 5, FIGS. 1 to 3)
[Patent Document 2]
JP 2002-239822 A (page 3 to page 5, FIGS. 1 to 3)
[Problems to be solved by the invention]
[0011]
In the above-described first conventional drilling tool, a back component force is generated on the outer peripheral blade 7B toward the axial center P of the tool in the radial direction, and the tool body 1 is bent in the direction of the back component force. As a result, the outer diameter of the corner blade 11 is reduced, and the hole diameter is reduced. Further, as the drilling process is continued, the outer diameter of the corner blade 11 is reduced even when the corner blade 11 is worn, and the diameter of the processed hole is reduced. Further, in machining with a high load on the drilling tool such as high feed machining, the drilling tool sways (so-called walking motion), the machining hole diameter becomes unstable, and in some cases the center blade 7A The outer peripheral blade 7B may be chipped or chipped.
[0012]
Although the above-described second conventional drilling tool can ensure straight advanceability of the tool body 1 when the machining hole is pulled out, the bending of the tool body 1 in the direction of the back force of the outer peripheral blade 7B. It could not be said that this was effectively suppressed. Moreover, it cannot be said that an effective measure for suppressing the reduction of the hole diameter due to wear of the corner blade 11 has been taken.
[0013]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a drilling tool in which reduction of the diameter of a processed hole in drilling is improved.
[0014]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve such an object, the drilling tool of the present invention has a central blade at the tip of a substantially cylindrical tool body rotated about the rotation axis (O). A throw-away tip and a throw-away tip having an outer peripheral blade are disposed on opposite sides of the rotation axis so that the rotation locus of the central blade and the outer peripheral blade around the rotation axis (O) is continuous in the radial direction. In the throw-away type drilling tool that is detachably attached by being shifted in the radial direction, the circumferential direction of the drilling tool is based on the position of the corner blade formed on the outermost peripheral portion of the outer peripheral blade. At least one pair in a range of −10 ° to 10 ° and a range of −10 ° to 10 ° in the circumferential direction of the drilling tool from a position symmetrical to the corner blade with respect to the rotation axis center (P). The guide pad is Protrudes from the outer peripheral surface of the body, at least the outer peripheral cutting edge located on the basis of the hole drilled the tool than the guide pad provided on -10 ° to 10 DEG in the circumferential direction is the corner cutting edge of the tool A throw-away drilling tool provided on the rear side in the rotation axis (O) direction of the main body .
[0015]
In the drilling tool having the above-described configuration, the guide pad provided along the rotation axis (O) direction of the tool main body on the outer periphery of the tip end of the tool main body slides on the inner wall of the machining hole to thereby remove the tool main body. Support and improve straightness. Further, the guide pad has a range of −10 ° to 10 ° in the circumferential direction of the drilling tool with respect to the position of the corner blade, and a position symmetrical to the corner blade with respect to the rotation axis center (P 1 ). Since at least one pair is provided in the range of −10 ° to 10 ° in the circumferential direction of the drilling tool, the tool body is supported in the acting direction of the back component force of the corner blade. The bending of the outer diameter of the corner blade due to the bending can be effectively suppressed. Therefore, reduction of the machining hole diameter is greatly suppressed. Moreover, when high feed processing is performed, a high cutting resistance is generated, thereby suppressing the whirling of the drilling tool, increasing the diameter of the drilled hole, and improving damage to the center blade and the outer peripheral blade.
[ 0016 ]
In the drilling tool, the guide pad is mounted so as to be movable in the radial direction of the tool body, and the difference in radius between the outermost peripheral part of the guide pad and the outermost peripheral part of the corner blade is -0.2 mm to 0 mm. It is preferable that the adjustment can be made within the above range. That way, if the difference between the radius -0.2mm or more, the guide pad, so to suppress the deflection of the machined hole inner wall and the sliding contact tool body inhibits the reduction of the processing hole diameter. When the absolute value of the difference in radius is close to 0 mm, the effect of suppressing the bending of the tool body of the guide pad becomes higher. Further, when the corner blade is worn out, the guide pad has a diameter of the corner blade. It acts to project outward in the direction, and suppresses the reduction of the bore diameter. However, the difference of the radii, since the expansion processing hole diameter exceeds the 0mm, it is desirable to 0mm or less.
[ 0017 ]
Further, in the drilling tool, the guide pad is preferably provided on the tool body axis of rotation (O) rearward side of the corner cutting edge. When the guide pad is provided behind the corner blade in the direction of the rotation axis (O) of the tool body, the guide pad maintains the effect of suppressing the bending of the tool body even when the corner blade comes out of the machining hole. To do. Therefore, the reduction of the diameter of the processed hole when the processed hole is pulled out is suppressed, and the whirling of the tool body is suppressed to prevent the peripheral blade and the center blade from being lost.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment of the drilling tool according to the present invention will be described with reference to FIGS. FIG. 1 is a front view of a tip portion of a drilling tool provided with a guide pad. FIG. 2 is a side view of the tool shown in FIG. 3A is a rear view of the drilling tool shown in FIG. 1, and FIGS. 3B and 3C are views of the guide pad (provided on the flute groove 3 side) of the drilling tool shown in FIG. FIG. 4 is a top side view of the tool shown in FIG. 1, and FIG. 5 is a bottom side view of the tool shown in FIG. 6A is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 6B is a cross-sectional view taken along the line BB in FIG. 7 (a) and 7 (b) are partially exploded perspective views of the tool shown in FIG.
[ 0019 ]
In the first embodiment, the tool body 1 has a round bar shape with the rotation axis O as the center, and the tool body 1 is connected to the spindle of the machine tool via a flange portion on the rear end (not shown) (right side in FIG. 1). A shank portion for gripping is formed. A pair of flute grooves twisted about the rotation axis O toward the rear side in the rotation direction K of the tool body 1 as it goes from the tip surface of the tool body 1 to the flange part on the outer peripheral part on the tip side of the flange part. 3, 4 are formed. As shown in FIG. 2, the flute grooves 3 and 4 are substantially L-shaped in cross section, and are formed on opposite sides around the rotation axis O, and the wall surface of the tool body 1 facing the rotation direction K is formed. It is the chip seat formation surface formed of tip seats 5, a wall surface facing the rotational direction K backwards is heel forming surface.
[ 0020 ]
The distal end of the tool body 1, the tip seat forming face flute grooves 3,4, the chip seat 5 forming a concave into the direction of rotation K rear side is formed, the chip 7 having cutting edges on the tip seat 5 Are fixed by screws 9. As shown in FIG. 1 and FIG. 3, the chip 7 is a chip 7 having a substantially parallelogram flat plate shape, and has two opposing rotationally symmetric end portions, and one longitudinal opposite end portion is The long side ridge part cutting edge 7a and the short side corner part cutting edge 7b are formed, and the other opposing end is formed by the long side side ridge part cutting edge 7c and the short side corner part cutting edge 7d. ing.
[ 0021 ]
The center edge 7A has a long edge ridge edge 7c and a short edge corner edge 7d located adjacent to the edge ridge edge 7c on the inner peripheral side as a bottom edge, and the outer edge 7B is The long edge ridge cutting edge 7a and the short edge corner cutting edge 7b located on the outer peripheral side adjacent to the edge ridge cutting edge 7a are the bottom edges. The corner cutting edge 7d adjacent to the corner cutting edge 7b, which is a bottom cutting edge, via the corner blade 11 is configured to give a clearance angle to the rotation axis O of the tool body so as to function as a back taper. Inclined. Further, the central edge 7A and the outer peripheral edge 7B are arranged so that the side ridge part cutting edge 7c and the side ridge part cutting edge 7a intersect each other in a rotation locus on a plane including the rotation axis O of the drilling tool. It is installed.
[ 0022 ]
As shown in FIGS. 2 and 3, the tool body 1 has a rotation direction from the position symmetrical to the corner blade 11 formed on the outermost peripheral portion of the outer peripheral blade 7 </ b> B with the rotation axis O as the center. At least one guide pad 21 </ b> A is provided along the rotation axis O direction and protrudes from the outer peripheral surface of the tool body 1 in a circumferential range of −10 ° to 10 ° to K. Since the first flute groove 3 is formed in the symmetrical positions in this embodiment, the guide pad 21A, a negative angle to the rotation direction K with respect to the symmetrical positions (the rotation direction K and the reverse 3) and at the rear side in the rotation axis O direction than the corner blade 11 as shown in FIG. 3. Further, the guide pad 21A is detachably fixed by the tool guide pad mounting groove 20A to the screw 22 which is recessed on the outer peripheral surface of the main body 1 as shown in FIG. 7, for example, the mounting groove and the guide pad 21A A spacer 23A is closely attached to 20A, and the outer diameter of the outer peripheral surface 21a of the guide pad 21A can be adjusted by changing the thickness of the spacer 23A. In addition, the guide pad 21A has a cross-section orthogonal to the rotation axis O and has an outer circumferential surface 21a having an outer diameter smaller than the outer diameter of the corner blade 11 of the drilling tool, as shown in FIG. 6B. It is formed so as to form a straight line having a length L1 in the rotation axis O direction.
[ 0023 ]
In such a drilling tool, a position that is -10 ° to 10 ° in the circumferential direction of the drilling tool with respect to the position of the cornering blade, and a position that is symmetrical to the cornering blade with respect to the rotation axis center (P). The guide pads 21A provided at least in a pair within a range of -10 ° to 10 ° in the circumferential direction of the drilling tool support the tool body 1 against the back component force of the outer peripheral blade 7B. The bending of the tool body 1 can be effectively suppressed. Therefore, a reduction in the outer diameter of the corner cutting edge 11 by the flexing effectively suppressed, the reduction of the processing hole diameter can be significantly suppressed. And the difference of the radius with respect to the outermost peripheral part of the said corner blade 11 of the outermost peripheral part of the outer peripheral surface 21a of the said guide pad 21A can be suitably adjusted in the range of -0.2 mm-0 mm. The difference between the radius of the guide pad 21A disappears contact machining hole wall and sliding is less than -0.2 mm, may effect of suppressing the reduction of the processing hole diameter can not be obtained, and processing the difference of the radius is greater than 0mm There arises a problem that the hole diameter is enlarged. Further, since the guide pad 21A is provided behind the corner blade 11 in the direction of the rotation axis O of the tool body 1, the effect of suppressing the bending of the tool body 1 even when the corner blade 11 comes out of the machining hole. Is maintained, the reduction of the diameter of the machining hole is suppressed, and the straightness of the tool body 1 is maintained, and the outer peripheral blade 7B and the central blade 7A are prevented from being lost.
[ 0024 ]
The rotation shape of the outer peripheral surface 21a of the guide pad 21A around the rotation axis O is a straight line having a length L1 in the direction of the rotation axis O as shown in FIG. It is preferable to set in the range of 0 mm. The reason for this is because the L1 is not effective sufficiently obtained to support the the tool body 1 since the sliding range of the rotation axis O direction of the processing hole inner wall and the outer peripheral surface 21a is narrowed is less than 1.5mm There, the L1 is because the load on the bore drilling tool intensified sliding contact with the outer peripheral surface 21a and the processing hole wall exceeds the 5.0 mm (resistance) increases. Note that the rotational shape of the outer peripheral surface 21a of the guide pad 21A around the rotational axis O may be, for example, an arc having a curvature radius R1, as shown in FIG. That way, even if the outer circumferential surface 21a occurs deflect the tool body 1 is inclined to the axis of rotation O, so the arc forming the outer peripheral surface 21a is in contact with the machined hole inner wall of the machined hole inner wall The finished surface roughness is not deteriorated. Also, depending on the magnitude of the force that presses the outer peripheral surface 21a to the processing hole inner walls, since the outer peripheral surface 21a is the machining hole wall and in sliding contact area is varied, the guide pad 21A is force substantially to the pressing A balancing force is applied to the tool body 1 to support the tool body 1. In the radius of curvature of less than 50mm of the rotational shape of the outer peripheral surface 21a, the outer peripheral surface 21a becomes insufficient effect for supporting the the tool body 1 becomes narrow machining hole wall in sliding contact region, the radius of curvature When R1 exceeds 1000 mm, can not eliminate the influence of inclination relative to the rotational axis O of the outer circumferential surface 21a, so deteriorating the finished surface roughness of the machined hole inner wall, the radius of curvature R1 is in the range of 50mm~1000mm preferable. Particularly preferably, the radius of curvature R1 is in the range of 50Mm～500mm. If it does so, the management of the inclination with respect to the rotating shaft O of the outer peripheral surface 21a of the guide pad 21A will be easy, and the finishing surface roughness of the inner wall of the processed hole will be stabilized.
[ 0025 ]
As shown in FIG. 2, the guide pad 21A is provided with one guide pad 21A at a substantially symmetrical position in the circumferential direction with respect to the rotation axis O of the tool body 1 of the outer peripheral blade 7B, and the position of the outer peripheral blade 7B. The other guide pad 21A is provided in a range of −10 ° to 10 ° in the circumferential direction of the drilling tool with respect to the position (in a circumferential direction substantially symmetrical to the one guide pad 21A). Also good. By doing so, the tool body 1 is further supported by the direction in which the back component force of the outer peripheral blade 7B acts by the two guide pads 21A, and the bending is suppressed, so that the reduction of the machining hole diameter is greatly improved. Is done. Furthermore, as shown in FIG. 2, a guide pad 21B may be provided on the outer periphery of the tool body 1 behind the outer peripheral blade 7B and the central blade 7A in the normal direction (lateral direction in FIG. 2). Then, the guide pad 21B supports the tool main body 1 in the main component force direction of the outer peripheral blade 7B and the central blade 7A, and suppresses bending in the main component force direction. This can more effectively suppress the reduction of the machining hole diameter in combination with the effect of suppressing the bending of the outer peripheral blade 7B in the back component force direction by the guide pad 21A described above. Therefore, it is possible to suppress the whirling of the drilling tool when performing high-feed machining, stabilize the machining hole diameter, and improve the damage to the cutting edge of the center blade 7A and the outer peripheral blade 7B.
[ 0026 ]
The drilling tool according to the present invention is not limited to the above-described embodiments, and can be implemented without departing from the gist of the present invention. The drilling tool is not limited to a drill, and is applied to, for example, a boring cutter, a BTA tool, and a trepanning tool. The tip that forms the cutting edge such as the outer peripheral blade and the center blade is not limited to the tip fixed to the tip seat integrally formed on the tool main body, but is fixed to the tool main body via a cartridge or the like. It may be a thing. Further, the manner of fixing the tip to the tool body is not limited to the screw-on type, and can be applied to all known types such as a clamp-on type and a wedge-type type, and the tip is applied to, for example, a steel cartridge. It may be a so-called blade type that is brazed.
[0027]
【The invention's effect】
The drilling tool of the present invention has a range of −10 ° to 10 ° in the circumferential direction of the drilling tool with respect to the position of the corner blade formed on the outermost peripheral portion of the outer peripheral blade, and the rotation axis center (P ) to the corner cutting edge and the range of -10 ° to 10 ° in the circumferential direction of the hole drilled tool from symmetrical positions relative to the at least one pair of guide pad protrudes from the outer peripheral surface of the tool body, A guide pad provided in a range of -10 ° to 10 ° in the circumferential direction of the drilling tool at least with respect to the position of the outer peripheral blade is located rearward in the rotation axis (O) direction of the tool body with respect to the corner blade. Is provided . Then, the guide pad supports the tool body in the back component force direction of the outer peripheral blade and suppresses the bending, so that the drilling tool suppresses the reduction of the outer diameter of the outer peripheral blade, Improves reduction of drilled hole diameter.
[Brief description of the drawings]
FIG. 1 is a front view of a tip portion of a drilling tool according to a first embodiment of the present invention.
FIG. 2 is a side view of the drilling tool shown in FIG. 1 as viewed from the tip.
3A is a rear side view of the drilling tool shown in FIG. 1, and FIG. 3B is a detailed view of a guide pad of the drilling tool shown in FIG. 3A.
(C) It is detail drawing of the other guide pad in the drilling tool shown to Fig.3 (a).
4 is a top side view of the drilling tool shown in FIG. 1. FIG.
5 is a lower side view of the drilling tool shown in FIG. 1. FIG.
6A is a cross-sectional view taken along line AA of the drilling tool shown in FIG.
(B) It is BB sectional drawing of the drilling tool shown in FIG.
7A is a partially exploded perspective view of the drilling tool shown in FIG.
(B) It is a partially exploded perspective view of the drilling tool shown in FIG.
FIG. 8 (a) is a rear side view of a tip portion of a first conventional drilling tool.
(B) It is a front view of the front-end | tip part of a 1st conventional drilling tool.
FIG. 9 is a detailed view of the cutting edge of the drilling tool shown in FIG. 8 ;
FIG. 10 is a front view of a tip portion of a second conventional drilling tool.
FIG. 11 is a side view of the drilling tool shown in FIG. 10 as viewed from the front end.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tool body 3, 4 Flute groove 7 Tip 7A Center blade 7B Peripheral blade 7a, 7b Outer peripheral edge ridge part 7c, 7d Central edge ridge part 11 Corner blade 21, 21A, 21B Guide pad 21a, 21b Guide pad outer peripheral surface 22 Screw 23A, 23B Spacer

Claims (2)

A throw-away tip having a central blade and a throw-away tip having an outer peripheral blade are disposed on opposite sides of the rotational axis at the tip of a substantially cylindrical tool body rotated about the rotational axis (O). In the throw-away type drilling tool, wherein the center blade and the outer peripheral blade are displaced in the radial direction so that the rotation trajectory around the rotation axis (O) is continuous in the radial direction and are detachably attached.
A range of −10 ° to 10 ° in the circumferential direction of the drilling tool on the basis of the position of the corner blade formed on the outermost peripheral portion of the outer peripheral blade, and the corner blade on the basis of the rotation axis center (P) At least one pair of guide pads protrudes from the outer peripheral surface of the tool body in a range of -10 ° to 10 ° in the circumferential direction of the drilling tool from a symmetric position, and at least the position of the outer peripheral blade is a reference. The guide pad provided in the range of −10 ° to 10 ° in the circumferential direction of the drilling tool is provided on the rear side in the rotation axis (O) direction of the tool body from the corner blade. Throw away type drilling tool. The guide pad is mounted so as to be movable in the radial direction of the tool body, and the difference in radius between the outermost peripheral portion of the guide pad and the outermost peripheral portion of the corner blade can be adjusted in a range of −0.2 mm to 0 mm. The throw-away drilling tool according to claim 1, wherein

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