JP3286836B2 - Indexable bite and its shank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away tool suitable for a small automatic lathe and the like and a shank thereof.
In particular, it relates to a support structure between a replaceable tip and a shank that supports the tip.

[0002]

2. Description of the Related Art Conventionally, small automatic lathes that perform selective or combined processing with a plurality of types of cutting tools have been used for the processing of all small parts such as bars and pipes.
There are many small shank tools, and when changing the cutting edge (tip), due to the structure of the stepped turret,
A design that makes the head of the cutting tool smaller is required.

For example, as schematically shown in FIG. 33, there is a shank 100 in which a triangular tip 101 is fixed with a clamp screw 102 as a replaceable cutting edge tip (a throw-away tip). Head 103
Has the disadvantage that the To keep this small,
As shown in FIG. 34, there is a chip in which a parallelogram-shaped chip 105 is fixed to a shank 100 with a clamp screw 102, and two diagonal cutting edges can be selectively used.

[0004]

As shown in FIGS. 35 and 36, such a parallelogram-shaped chip 105 is placed on a tip holder 107 at the tip end of a shank 100, for example, in the upright state at the center thereof. Screw 10 penetrating through
2 fixed. At this time, the two sides (two side surfaces) of the chip 105 are provided on the receiving surfaces A and B on the two sides of the chip holder 107.
Is pressed to support the chip 105, but it is difficult to accurately contact the two side surfaces of the chip 105 with the receiving surfaces A and B, respectively. For example, FIG.
As conceptually shown in (c), if a clearance occurs due to a processing error between the receiving surfaces A and B and the chip side surface,
There are problems such as a decrease in the positional accuracy and restraint of the insert, a slight shift in the cutting edge of the insert, and the occurrence of chatter vibration during machining.

SUMMARY OF THE INVENTION It is an object of the present invention to stably support a parallelogram-shaped chip to a chip holder portion of a shank with a clamp screw, thereby enhancing the constraint of the chip.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a shank and a parallelogram-shaped chip removably attached to a tip holder at the tip of the shank, and is located on a diagonal line of the chip. A cutting edge is formed at the two sharp corners, and a clamp screw that penetrates the center of the tip in the thickness direction is fastened to the tip holder of the shank, so that the tip is fixed to the tip holder. And It is also assumed that the shank used for this is used. The diamond shape is a special form of a parallelogram. Then, the tip holder portion of the shank is formed in a shape into which any one acute angle portion of the tip can be inserted. For example, the side of the shank is concavely cut out in an acute angled form so that its sharp edge can be fitted. The chip holder is formed so as to face a clamped surface of the chip (for example, one of the front and back surfaces of the chip) in opposition to the tightening of the clamp screw, and to rise up from the bottom surface into a wall shape. And first and second receiving portions respectively receiving the first and second sides (side surfaces) constituting the acute angle portion. The first receiving portion is formed substantially parallel to the longitudinal direction of the shank, the second receiving portion is formed in a direction intersecting with the longitudinal direction of the shank, and both ends of the first receiving portion and the second receiving portion are formed. At three places with the end of the receiving portion of the chip on the insertion side of the chip, the chip comes into contact with the side surface of any one acute angle portion of the chip.

[0007] With such a structure, the tip is firmly fixed to the tip holder of the shank at three points around the center of the clamp screw, so that the positional accuracy around the clamp screw is improved and the processing time is increased. The displacement is unlikely to occur even with the load described above, and the constraint of the chip is improved. In addition, since the chip is a parallelogram and is fixed with a clamp screw without using a clamp piece, compared with a triangular chip or the like using a clamp piece,
As a throw-away tool which can reduce the shank head (bite head) and satisfy both compactness and restraint stability, it can be suitably used for small automatic lathes and the like.

Specifically, as a three-point support structure as described above, for example, a first flank is provided at an intermediate portion of the first receiving portion of the tip holder portion of the shank so as to be away from the first side surface of the tip. By being formed, two contact portions that contact the first side surface of the chip are formed on both sides of the first flank. Further, a second clearance surface is formed in the second receiving portion of the chip holder portion with a predetermined clearance angle away from the second side surface of the chip, with the end of the chip insertion side as a base point. Thereby, one contact portion that contacts the second side surface of the chip is formed at the end on the chip insertion side, which is the base end of the second flank.

Preferably, the apex angle of the acute angle portion of the chip is set, for example, in the range of 45 to 80 °, and the clearance angle of the second flank formed in the second receiving portion is, for example, 0 °. .5 to 2 °. If the apex angle of the tip is smaller than 45 °, durability problems such as chipping and the like, and the stability of the clamp of the tip and consequently the restraint stability may decrease,
If it is larger than 80 °, disadvantages such as a large amount of protrusion from the shank and difficulty in downsizing are likely to occur.
The above range is desirable. On the other hand, if the clearance angle of the second flank is smaller than 0.5 °, it is difficult to uniquely apply the contact portion with the chip side surface to the end on the chip insertion side.
If it is larger than ゜, the above range is preferable from the viewpoint that the abrasion of the contact portion with the chip and the support rigidity are reduced.

Further, in addition to the above-mentioned three-point support, the outer edge of the chip and the receiving portion of the chip holder receiving the tip may be tapered so that the acute-angled cross-sections (taper) fit together. it can. That is, at least one (preferably both) of the first and second side surfaces of the chip acute angle portion is in a range of 2 to 20 degrees, such as 3 to 7 degrees, relative to a surface perpendicular to the clamped surface of the chip. It is formed to be inclined to the acute angle side, the first of the tip holder part of the shank,
At least one of the second receiving portions (preferably both)
The chip holder is formed to be inclined to an acute angle side that is equal to or greater than the acute angle inclination of the side surface of the chip with respect to a plane perpendicular to the bottom surface of the chip holder portion. At least one of the acutely inclined first and second side surfaces of the chip and at least one of the acutely inclined first and second receiving portions of the chip holder portion corresponding thereto.
The tip is inserted along the bottom surface of the tip holder portion of the shank so that the receiving portion and the receiving portion are fitted to each other at the acute-angled inclined portions.

As described above, the combination of the three-point support and the taper fitting between the tip and the shank allows the tip to be clamped, restrained to the tip holder portion while having a fixed structure using a clamp screw without using a clamp piece. Further, the positioning accuracy is synergistically enhanced. That is, the three-point support increases the positional accuracy of the cutting edge of the tip and stabilizes the support of the tip, but furthermore, the taper fitting between the tip and the tip holder part is added, so that the combination with the fastening force of the clamp screw is achieved. By alignment, the constraint of the clamped surface on the bottom surface of the chip holder is improved,
In addition, the position accuracy also increases.

If the angle of inclination of the chip is smaller than 2 °, it is difficult to obtain the effect of enhancing the restraint of the chip, and if it is larger than 20 °, the strength of the outer edge of the chip or the clamp hole penetrating the center of the chip. The above-mentioned range is desirable from the viewpoint that the degree of freedom of the size is easily restricted or restricted. The inclination angle of the tip holder portion on the shank side is also set substantially corresponding to the inclination angle of the chip from the viewpoint of the effect of the chip restraint, the strength of the chip holder portion, and the like. If the angle is slightly larger than the inclination angle (for example, about 0.3 to 2 °), the chip holder comes into contact with the chip side surface in the vicinity of the opening-side end of the receiving portion of the chip holder portion, so that the chip restraining effect is more reliable. Becomes

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings. A throw-away bite 1 shown in FIG. 1 has a shank 2 corresponding to a handle, a throw-away tip (hereinafter simply referred to as a tip) 3 which is exchangeably attached to the tip, and the tip 3 is clamped to the shank 2. And a clamping screw 4. The material of the shank 2 is steel (carbon steel) or a cemented carbide. The material of the tip 3 is cermet, cemented carbide or the like. For example, in the case of cermet, T
A TiC-TiN-based cermet having a finer structure by adding iN, a cermet mainly composed of TiN instead of TiC, or the like can be used. Further, as the cemented carbide, a particulate cemented carbide in which a WC hard layer, which is a main component thereof, is refined to about 1 μm can be used. Further, the particulate cemented carbide is used as a base material, and TiN or TiCN is added thereto. Appropriate materials such as those coated with PVD can be used.

A tip holder 6 is provided at the tip of the shank 2.
As shown in FIG. 5, the side surface of the shank 2 is concavely cut out by an amount substantially corresponding to the plate thickness of the chip 3, and the chip 3 is attached in an upright state. In other words, one of the front and back chip surfaces of the chip holder portion 6 becomes the clamped surface 7, and this is seated on the vertical bottom surface 8 of the chip holder portion 6.

Returning to FIG. 1, the tip 3 has a parallelogram shape, and a clamp hole 9 for passing the clamp screw 4 is formed at the center thereof in the plate thickness direction, and two diagonal lines are formed. It has a sharp edge 10 with a cutting edge 11 at each end, and if one wears, it can be turned 180 ° and the other can be used. The tip holder portion 6 of the shank 2 has a shape into which one acute angle portion 10 of the tip 3 can be inserted, and is attached to the first and second sides (side surfaces) 12 and 13 of the tip 3 forming the acute angle portion 10. Corresponding first and second receiving portions 14 and 15 are provided. The receiving portion 14 is formed parallel to the longitudinal direction of the shank 2, and the receiving portion 15 is formed so as to obliquely cross the shank 2, and a portion where they intersect is substantially flush with the bottom surface 8 of the chip holder portion 6. The opening 16 is provided. Each of these receiving portions 14 and 15 is formed in the shape of a wall rising from the bottom portion 8 and has a height substantially equal to the thickness of the chip 3 as described above. In FIG. 1, the shank 2 of the receiving portion 15 is shown for easy understanding.
The upper end of the receiving portion 15 in the drawing and the upper end of the rear surface of the chip 3 are in contact with each other, and the portion below the upper end is an acute clearance (exaggerated).
Occurs.

In FIG. 1, the lower side of the receiving portion 14 is a cutting tool head (shank head) 17, which slightly protrudes below the main body of the shank 2. At right angles to the bottom surface 8, a female screw hole 18 is formed toward the opposite side surface, and the above-mentioned clamp screw 4 is screwed through the clamp hole 9 of the chip 3. Incidentally, as shown in FIG.
In the chip holder part 6 of FIG.
May be connected at intersections (having no open portion 16).

As shown in FIG. 3, the sharp corner 10
Is set, for example, in the range of 45 ° to 80 °, and the tip 3 is fixed on the side surface of the shank 2 so that the tip 3 does not protrude from the shank 2 and the bolt 3 The head 17 is also small, and has a compact form close to a solid cutting tool.

As shown in FIG. 3, a flank 21 is provided at an intermediate portion of the first receiving portion 14 of the tip holder portion 6 of the shank 2.
Are formed in a concave shape with a slight depth away from the chip side surface 12, whereby two contact portions P1 and P2 with the chip side surface 12 are formed on both sides thereof. These contact portions P1 and P2 are located substantially on both sides of the clamp screw 4. On the other hand, the flank 23 of the second receiving portion 15 of the chip holder portion 6 is spaced from the chip side surface 13 by a distance of about 0.5- Relief angle θ in the range of 2 °
2 is formed. As a result, a third contact portion P3 that is in contact with the chip side surface 13 is set near the chip insertion side end 22 of the second receiving portion 15.

By forming the flank surfaces 21 and 23 as described above, as shown in FIG. 4, the tip 3 is conceptually put on the tip holder of the shank 2 by three-point support of P1, P2 and P3. It will be supported by the part 6. Such supporting points (contact portions P1 to P3) are located at substantially the same angle and at the same distance with respect to the clamp screw 4 for clamping the chip 3, so that the chip 3 can be accurately positioned and processed. Will be distributed as appropriate.

As shown in FIG. 5, the side surfaces 12 and 13 (represented by 12 in the figure) forming the outer edge of the chip 3 are at an angle with respect to a surface (reference surface H1) perpendicular to the surface 7 to be clamped. It is formed to be inclined to the acute angle side by θ3. It can be said that the taper is given, and the taper angle θ3 '
Is an acute angle of 90 ° -θ3. This θ3 is, for example, 2-2
A range of 0 °, especially a range of 3 to 7 °, is particularly preferred.
Note that the chip side surface 13 in FIG. 1 is also provided with a similar inclination angle (taper angle).

The first and second receiving portions 14 and 15 of the tip holder portion 6 of the shank 2 are also provided on the bottom surface 8 of the shank 2 as shown in FIG. 5 (represented by the receiving portion 14 in this figure). It is formed so as to be inclined to the acute angle side by an angle θ4 with respect to a perpendicular surface (reference surface H2). This inclination angle (taper angle) θ4 is
The inclination angle θ3 of the chip 3 may be substantially the same, but it may be desirably larger by a certain amount (for example, about 0.3 to 1.5 °). The taper angle θ4 ′ of the receiving portion 14 is an acute angle of 90 ° −θ4. If θ3 <θ4, the taper angle θ4 ′ is slightly smaller than the taper angle θ3 ′ of the chip 3.

In this case, as shown in an exaggerated manner in FIG. 6, the inclination angle θ4 of the receiving portion 14 of the chip holder 6 is larger than the inclination angle θ3 of the chip side surface 12.
The tip 3 is in contact with the tapered portion on the opening end side of the receiving portion 14 at the tapered portion on the outer edge side, and the taper angle (θ3,
Based on θ4), it is attached to the tip holder 6 with high accuracy and high restraint.

FIG. 7 conceptually shows a section taken along the line RR in FIG.
As is clear from this figure, the tip 3 cannot be mounted on the bottom face 8 of the shank 2 from a direction perpendicular to the bottom face 8 of the tip holder 6 of the shank 2. That is, as shown in FIG. 1, the tip 3 is moved from the direction parallel to the bottom surface 8 of the tip holder 6 of the shank 2 to the first and second receiving portions 14 and 15.
Will be inserted along the line. Conceptually speaking, the tip holder portion 6 of the shank 2 in FIG. 7 has a so-called dovetail groove form, and the chip 3 having a flat trapezoidal cross section is formed along the dovetail groove. Can be said to be plugged.

Then, the clamp screw 4 is screwed into the female screw hole 18 of the shank 2 through the clamp hole 9 of the chip 3, so that the chip 3 is attached to the bottom surface 8 of the chip holder 6 by the clamping force of the clamp screw 9. The clamped surface 7 is pressed, and the inclined tip side surfaces 12 and 13 are engaged with the inclined first and second receiving portions 14 and 15, and the clamping state of the tip 3 is stabilized by a synergistic effect of these. Will be maintained. That is, if such inclined surfaces (tapered surfaces) 12, 13, and 14, 15 do not exist,
Since the tip 3 is fixed to the shank 2 only by the clamping force of the clamping screw 4, the clamping force is weak.
By applying the above-described restraining force by the tapered surface, high restraint properties can be obtained as a whole.

In FIGS. 1 to 7 described above, the shape of the tip and the shank and the like are conceptually drawn to some extent in order to make the description easy to understand. The following shows the form of a simple chip.

The chip 30 shown in FIGS. 8 to 13 is used for parting off (or grooving) the work W, for example, as shown in FIG. As shown in FIG. 8, a thick portion 31 is formed so as to protrude from one of the front and back surfaces of the chip 30, and the chip surface becomes a clamped surface 32.
In other words, the acute angle portions 10 on both sides excluding the thick portion 31
Can be said to have been reduced in thickness by a certain amount. This thick part 31
Is formed so as to penetrate through the thick portion 31.
Have upright walls 33 that form a triangular or chevron shape with the cutting edge 11 of each acute angle portion 10 as the apex, and the ridge lines of each upright wall are parallel to each other.

Each of the long side surface 12 and the short side surface 13 of the chip 30 has an inclination angle (θ3) as shown in FIGS. Strictly speaking, a short vertical wall portion 12a is formed along a plane perpendicular to the clamped surface 32, and subsequently, an inclined surface (taper surface) 12b having an angle θ3 is formed on the first chip side surface 12. Have been. The second receiving portion 13 also has a vertical wall portion 13a perpendicular to the clamped surface 32, followed by an inclined surface (tapered surface) 13b having an angle θ3. The tip holder 6 of the shank 2 has the θ
As described above, the taper is provided at an inclination angle equal to or larger than 3.

The chip 40 shown in FIGS.
As shown in FIG. 1, the chip is suitable for post-grinding (collar back processing for processing the back surface of the flange). As shown in FIG. 16, in the chip 40, a relief portion 42 is formed on the long side 12 of the parallelogram on the side of the acute angle portion 10, so that a slight step is formed. Each of the cutting edges 11 is suitable for back-grinding. As shown in FIGS. 19, 20, etc., the first and second chip side surfaces 12, 13 have vertical wall portions 12a, 13
a, an inclined surface (tapered surface) 12b inclined at an angle θ3,
13b. As described above, the tip holder 6 of the shank 2 is formed with a tapered surface into which it is inserted.

The chip 50 shown in FIGS.
As shown in FIG. 8, it is used for external thread cutting. As shown in FIG. 22, the cutting edge is for thread cutting.
It is sharply formed so as to form a vertex of a triangle. As shown in FIGS. 26 and 27, the chip side surfaces 12 and 13 have vertical wall portions 12a with respect to the clamped surface 51.
13a and inclined surfaces (tapered surfaces) 12b, 13 having an angle θ3
b are formed and these are the tip holder portions 6 of the shank 2.
Is pressed against the tapered surface formed at the bottom.

The cutting tool in which various chips shown in FIGS. 1 to 7 or FIGS.
It is suitably used for so-called small automatic lathes. For example, FIG.
In the so-called comb-shaped small automatic lathe shown in FIG. 9, various cutting tools B1 to B5 for cutting off, grooving, or front grinding, rear grinding, and threading as described above are attached to the blade base 60, and the work holder 61 The tools B1 to B5 selectively process small workpieces such as pipes and rods held in the workpieces.

FIG. 30 shows a so-called cam type automatic lathe in which various cutting tools B1 to B5 are arranged radially with respect to the work W. In FIG. 31, various tools B1 to B5 are mounted on a turret 62, and predetermined processing is performed by indexing rotation. FIG. 32 shows an automatic lathe in which a comb shape is bent at a right angle, and selective or complex processing is performed by various tools B1 to B5.

In the above-described processing such as turning in a small automatic lathe, for example, the chips 3, 30, 40, 5
Reference numeral 0 denotes an inclined surface which is positioned at the tip holder portion 6 of the shank 2 with three-point support as conceptually shown in FIG. 4, and is formed corresponding to the tip side surface and the receiving portion on the tip holder portion side, respectively. Since the (tapered surfaces) are fitted to each other, the overall positioning accuracy and the clamping force are improved, which enables high-precision processing and contributes to suppressing chatter vibration and the like.

[Brief description of the drawings]

FIG. 1 is a view showing a throwaway byte according to an embodiment of the present invention.

FIG. 2 is a diagram showing a modified example thereof.

FIG. 3 is an enlarged front view showing a main part of FIG. 1;

FIG. 4 is a view conceptually showing a support point of the chip.

FIG. 5 is a view for explaining an inclination angle of a shank and a tip.

FIG. 6 is a diagram conceptually and partially exaggerating the mounting state of both.

FIG. 7 shows a state in which the tip is fastened with a clamp screw in FIG.
FIG.

FIG. 8 is a plan view of a chip as another embodiment.

FIG. 9 is a front view thereof.

FIG. 10 is a rear view of FIG. 9;

FIG. 11 is a sectional view taken along the line BB in FIG. 8;

FIG. 12 is a left side view of FIG. 9;

FIG. 13 is a view taken in the direction of arrow C in FIG. 9;

FIG. 14 is a diagram showing an example of a chip processing mode.

FIG. 15 is a plan view of a chip according to another embodiment.

FIG. 16 is a front view thereof.

FIG. 17 is a rear view of FIG. 16;

18 is a sectional view taken along line DD in FIG.

FIG. 19 is a left side view of FIG. 16;

FIG. 20 is a view as seen in the direction of arrow E in FIG. 16;

FIG. 21 is a diagram showing an example of a chip processing mode.

FIG. 22 is a plan view of a chip of another embodiment.

FIG. 23 is a front view thereof.

FIG. 24 is a rear view of FIG. 23;

FIG. 25 is a sectional view taken along line FF in FIG. 22;

FIG. 26 is a left side view of FIG. 23.

FIG. 27 is a view on arrow G of FIG. 23;

FIG. 28 is a diagram showing an example of a processing form of the chip.

FIG. 29 is a view conceptually showing an example of a comb-shaped small automatic lathe.

FIG. 30 is a view conceptually showing an example of a cam-type small automatic lathe.

FIG. 31 is a view conceptually showing an example of a turret type small automatic lathe.

FIG. 32 is a view conceptually showing an example of an automatic lathe in which the comb type is modified.

FIG. 33 is a view exemplifying a byte provided with a conventional triangular chip;

FIG. 34 is a view exemplifying a cutting tool provided with a chip having a parallelogram shape;

FIG. 35 is a diagram illustrating a conventional problem.

FIG. 36 is a view illustrating a conventional tip mounting mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throw-away tool 2 Shank 3, 30, 40, 50 Tip 4 Clamp screw 6 Tip holder part 7 Clamped surface 8 Bottom surface 9 Clamp hole 10 Sharp corner 11 Cutting edge 12 First tip side 13 Second tip side 14 One receiving portion 15 Second receiving portion 21, 23 Flank 22 End of chip insertion side

Claims (6)

(57) [Claims] 1. A shank and a parallelogram-shaped chip removably attached to a tip holder at the tip of the shank. A cutting edge is formed at two acute angles located on a diagonal line of the chip. Wherein the tip is fixed to the tip holder by a clamp screw that penetrates the center of the shank in the thickness direction, and the tip is fixed to the tip holder. A bottom surface that receives the clamped surface of the chip in opposition to the tightening of the clamp screw, and is formed to rise like a wall from the bottom surface; First and second receiving portions for receiving first and second sides (side surfaces) constituting the acute angle portion of the chip, respectively, and the first receiving portion The second receiving portion is formed substantially in parallel with the longitudinal direction of the shank, and is formed in a direction intersecting with the longitudinal direction of the shank, and at least two places of the first receiving portion and the second receiving portion. At least three places of the receiving portion and the end on the chip insertion side, a structure that abuts the side surface of any one of the acute angle portions of the chip, wherein an intermediate portion of the first receiving portion has The first flank is formed so as to be away from the first side surface, so that two contact portions corresponding to the first side surface of the chip are formed on both sides of the first flank, Further, a second clearance surface is formed in the second receiving portion at a predetermined clearance angle so as to be separated from the second side surface of the chip, with the end of the chip insertion side as a base point. The tip insertion, which is the base end of the second flank, The end on the side, a second side one portion of throwaway bytes abutment is formed which corresponds with the tip. 2. An apex angle of an acute angle portion of the chip is set in a range of 45 to 80 °, and a clearance angle of a second flank formed in the second receiving portion is 0.5 to 2 degrees. The throw-away byte according to claim 1, wherein the throw-away byte is set in a range of ゜. 3. At least one of the first and second side faces of the acute angle portion of the chip is inclined to the acute angle side in a range of 2 to 20 ° with respect to a plane perpendicular to the clamped surface of the chip. And at least one of the first and second receiving portions of the tip holder portion of the shank is equal to or at an acute angle to the side surface of the tip with respect to a surface perpendicular to the bottom surface of the tip holder portion. At least one of the acutely inclined first and second side surfaces of the tip and the acutely inclined first and second receiving portions of the chip holder portion corresponding to the acutely inclined first and second side surfaces are formed. 3. The throw according to claim 1, wherein the tip is inserted along the bottom surface of the tip holder portion of the shank such that at least one receiving portion is fitted at the acute angle inclined portions. Away Part-Time Job. 4. A shank and a parallelogram-shaped tip detachably attached to a tip holder portion at a tip end thereof, wherein a cutting edge is formed at two acute corners located on a diagonal line of the tip, and the tip is formed. In a shank of a throw-away tool in which the tip is fixed to the tip holder by a clamp screw penetrating the center part of the shank in the thickness direction, the tip holder of the shank is: The chip is formed into a shape into which any one acute angle portion can be inserted, and is formed to have a bottom surface that receives the surface to be clamped of the chip in opposition to the tightening of the clamp screw, and to be formed into a wall shape from the bottom surface. And first and second receiving portions respectively receiving first and second sides (side surfaces) constituting the acute angle portion of the chip. A receiving portion of the shank is substantially parallel to the longitudinal direction of the shank, the second receiving portion is formed in a direction intersecting the longitudinal direction of the shank, and at least two places of the first receiving portion, At least three places with the end on the chip insertion side of the second receiving portion, a structure in contact with the side surface of any one of the acute angle portions of the chip, wherein the intermediate portion of the first receiving portion A first flank is formed so as to be separated from the first side surface of the chip, so that two contact portions contacting the first side surface of the chip on both sides of the first flank surface Is formed, and a second clearance surface is formed in the second receiving portion with a predetermined clearance angle away from the second side surface of the chip, with the end of the chip insertion side as a base point. That is, before the proximal end of its second flank Chip to the end portion of the insertion side, the tip of the second indexable byte shank abutment one place hit the side surface is formed. 5. The shank of claim 4, wherein the clearance angle of the second flank formed in the second receiving portion is set in a range of 0.5 to 2 °. 6. At least one of the first and second side surfaces of the acute angle portion of the chip is inclined to the acute angle side in a range of 2 to 20 ° with respect to a surface perpendicular to the surface to be clamped of the chip. And at least one of the first and second receiving portions of the tip holder portion of the shank is equal to or at an acute angle to the side surface of the tip with respect to a surface perpendicular to the bottom surface of the tip holder portion. At least one of the acutely inclined first and second side surfaces of the tip and the acutely inclined first and second receiving portions of the chip holder portion corresponding to the acutely inclined first and second side surfaces are formed. At least one
The indexable bite according to any one of claims 4 to 5, wherein the tip is inserted along the bottom surface of the tip holder portion of the shank so that the receiving portion and the receiving portion are fitted to each other at the acute angle inclined portions. Shank.