JPH11347826A - Throwaway tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cutting resistance by specifying the relation between the rake angles of the side ridge sections and corner sections of the rake faces formed on the upper face of a polygonal flat plate-like tip main body and the relation between the land widths of the cutting edges with constant-width lands formed over the whole peripheries of front cutting edges and main cutting edges. SOLUTION: Rake faces 3 having curved surfaces recessed inward in the tip thickness direction are formed on the upper face of a polygonal flat plate- like tip main body 1 having clearance angles on outer peripheral side faces 2, and front cutting edges 6 and main cutting edges 7 are formed on the cross ridge line sections between the rake faces 3 and the outer peripheral side faces 2. The rake faces 3 are formed to satisfy the relation θ1<θ2 between the rake angle θ2 of side ridge sections 5 and the rake angle θ1 of corner sections 4, and dimples are formed at prescribed intervals on the rake faces 3. Constant- width lands 9 are adjacently formed on the cutting edges 6, 7, and the lands 9 are formed to satisfy the relation W2<W1 between the land widths W1, W2 of the cutting edges 6, 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert mounted on a throw-away type cutter for face cutting, and more particularly, to a curved cutting edge formed so that cutting force can be reduced without lowering the cutting edge strength. It was done.

[0002]

2. Description of the Related Art Conventionally, in turning, in order to reduce cutting resistance, a so-called positive type insert tip (hereinafter referred to as "tip") provided with a clearance angle or a cutting edge is used. A chip having a breaker groove formed at the rear is used. The reason why the positive type tip is used is to avoid the interference between the workpiece and the tip and form a rake angle. Although the breaker groove is originally intended to improve the chip controllability, it also has the above-mentioned role. Similarly, in the case of milling with a rotary tool, various types of chips have been provided in order to reduce cutting resistance, and in fact, a chip having a complicated shape with a breaker groove leads the processing industry. Up to.

For example, Japanese Patent Application Laid-Open No. Hei 8-257822 discloses a substantially square tip mounted on a throw-away type cutter. Here, the chip is introduced as an example.

[0004] The tip body 20 is a positive type tip provided with a clearance angle in order to reduce cutting resistance, and a breaker groove 22 is provided on an upper surface 21 thereof along a cutting edge. The shape of the breaker groove 22 is specified by an arc-shaped curve connected from both ends so as to be deepest and wide at each central portion of the main cutting edge 23. The cross section of the breaker groove 22 has an inclined surface 26 gradually lowering from the land 24 toward the boss surface 25 and an inclined surface 27 rising from the bottom toward the boss surface 25.
Are formed. Further, irregularities are arranged on the inclined surface 27 at regular intervals in a direction along the main cutting edge 23.

[0005]

Here, the problems of the prior art will be described below.

In the prior art, a substantial rake angle is increased by forming a breaker groove in a positive type chip. The clearance angle of the side surface is large, and the rake angle is increased as the breaker groove is deeper. It has a configuration that can be used.

However, as the rake angle increases, the wedge angle at the tip of the cutting edge decreases, so that there is a problem that the strength of the cutting edge necessarily decreases. Such problems are particularly important in milling, which always results in interrupted cutting. Further, when the mounting angle of the tip of the cutter body is set to be large, the back metal is reduced, which may cause the rigidity of the cutter body to decrease.

[0008] For these reasons, the above-mentioned prior art has been quite useful in reducing cutting resistance.
On the other hand, there has been a demand for the development of a chip capable of reducing the cutting resistance without reducing the cutting edge strength and the rigidity of the cutter body.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a polygonal flat chip body having a clearance angle on an outer peripheral side surface. A rake surface formed of a curved surface concaved inward is formed, and a crossing ridge line formed by the outer peripheral side surface and the rake surface is provided with a front cutting edge and a side ridge formed by cutting a chamfered shape provided at a corner. A main cutting edge is formed, and each cutting edge is provided with a land having a fixed width over the entire circumference. In a throwaway insert for a rotary tool, the rake face is formed by a cutting edge. From the top to the center of the chip, and the angle between the rake angle θ2 of the side ridge and the rake angle θ1 of the corner is θ.
A relationship of 1 <θ2 is formed, and dimples are arranged on the rake face at predetermined intervals in a direction along the cutting edge, and the land is a land W2 of a front cutting edge and a main cutting edge. And the land width W1 has a magnitude relationship of W2 <W1, and the main cutting edge extends from one corner to an intermediate point with another corner formed adjacently. It is characterized in that it is formed in a curved shape that becomes gradually lower at an inclination angle of 15 °.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 4 show a first embodiment. The chip body 1 has a square plate shape in plan view, and has a pair of upper and lower surfaces arranged in the thickness direction, and outer peripheral side surfaces (hereinafter, referred to as “hereafter”) arranged around the upper and lower surfaces and provided with a predetermined clearance angle γ. This is a so-called positive type chip consisting of a “flank surface”. On the upper surface, a curved surface (hereinafter, referred to as a “rake face”) 3 which is recessed inward in the chip thickness direction and a chip mounting hole 11 penetrating in the thickness direction at the center of the rake face 3 are formed as a whole. I have.

At the intersection of the rake face 3 and the flank face 2,
Front cutting edge 6 cut into chamfered shape provided at corner 4
And a main cutting edge 7 provided on the side ridge portion 5, and a land 9 is formed so as to be inscribed in each cutting edge. The land 9 is effective for preventing chipping and chipping, and the size of the land greatly affects the cutting characteristics. For this reason, in the present invention, the land width is selected from the range of 0.05 to 0.5 mm, and the difference in the role between the front cutting edge 6 and the main cutting edge 7 is taken into consideration. Land width W1 and main cutting edge 7 land width W2
And W2 <W1. This is because the front cutting edge 6 gives priority to the cutting edge strength, and the main cutting edge 7 gives priority to sharpness.

On the inner side of the land 8, a mortar-shaped inclined surface 12 which becomes lower toward the inner circumferential direction of the chip is formed. The rake angle of the inclined surface 12 is selected from the range of 5 to 40 ° from the viewpoint of maintaining the balance between sharpness and cutting edge strength, and furthermore, as shown in FIGS. The rake angle is set to be different from that of the edge 5.
That is, a magnitude relationship of θ1 <θ2 is formed between the rake angle θ2 of the side ridge 5 and the rake angle θ1 of the corner 4. In the front cutting, it was considered that the position where the cutting edge is likely to be broken is on the front cutting edge 6 side of the corner 4 and the position where sharpness is required is on the main cutting edge 7 side of the side ridge 5. Things.

On the rake face 3, the adhesive force between the chips discharged by the cutting edges 6 and 7 and the rake face 3 is reduced, and in order to prevent chip clogging and the like, an increase in cutting resistance is suppressed. For this purpose, the dimples 10 are arranged at regular intervals in the direction along the cutting edges 6 and 7. This dimple 10
Plays the role of oil pocket during wet cutting,
It works to improve lubricity. This further reduces the contact area, which is effective in solving such a problem.

The main cutting edge 6 provided on the side ridge 5 is formed in a curved shape, and has the lowest position at an intermediate point of the side ridge 5. Side view, inclination angle α of main cutting edge 6 is 3 to 15
° is set. If this angle exceeds 15 °, it is clear that the meaning of increasing the strength by increasing the thickness of the tip becomes insignificant, and the strength of the cutting edge decreases. On the other hand, the ridgeline of the cutting edge provided at the corner 4 forms a ridgeline of the cutting edge which is entirely convex. Thereby, sharpness is improved, chatter vibration is suppressed, and it is effective in preventing chipping and chipping. Here, the sharpness is improved because the rake angles in the radial direction and the axial direction are substantially increased. The reason why chatter vibration is suppressed is that the outflow direction of the chip differs at each position of the cutting edge involved in cutting, and the chip separation from the cutting edge is improved. The reason why it is effective in preventing chipping and chipping will be described in detail with reference to FIG.

In the case of a positive type chip having upper and lower surfaces formed in parallel, in the case of a chip having a straight cutting edge, the axial rake angle β1 is restricted by the clearance angle γ. Therefore, the axial rake angle β
In order to set 1 to be large, the cutting resistance cannot be reduced and the sharpness cannot be improved unless the clearance angle γ is increased in addition to the tip mounting angle of the cutter body 13. However, providing a large relief angle γ causes a problem that the cutting edge strength is reduced at the same time.

Therefore, the present invention provides a main cutting edge 7 provided on the edge 5 of the chip in a curved shape so as to be gradually lower from one corner to an intermediate point with another adjacent corner. By reducing the cutting edge strength, the cutting resistance is reduced and the sharpness is maintained or improved. That is, increasing the rake angle in the axial direction from β1 to β2 is to reduce the cutting force acting in the rotating direction of the cutter, to process a material having no clamping rigidity, to process a thin material, and to use a low-power, low-rigidity machine. This makes it possible to perform stable cutting even in the processing by cutting.

However, simply inclining the cutting edge straight from the corner 4 will reduce the strength of the tip of the cutting edge. Therefore, according to the present invention, the intersection between the front cutting edge 6 and the main cutting edge 7 is not required. By smoothly connecting the joints with the arc curve, a decrease in cutting edge strength is avoided.

FIG. 6 shows the entire cutter with the chip of the present invention mounted. The cutter body 13
It has a hollow disk shape, and is roughly composed of a front surface 14, a side surface 15, and a back surface 16. The front face 14 is the face facing the workpiece, and the back face 16 is the face facing the spindle end of the machine. The side surface 15 gradually increases in diameter from the front side 14 toward the upper side in the axial direction, and is a surface such as a tapered surface. Front 14 and side 1
The chip mounting seat 17 that opens in the radial direction and the axial direction is formed at the intersection ridge line portion 5. The chip according to the present invention is placed on the bottom wall surface of the chip mounting seat 17 via a metal deposit, and is fixedly fastened by a tightening screw 18 inserted into the center mounting hole. The main cutting edge 7 of the tip is arranged so as to face the outer peripheral side, and the front cutting edge 6 is arranged so as to face the front.

FIGS. 7 to 9 show a second embodiment, in which the same parts as those described above are designated by the same reference numerals.
Detailed description is omitted. This chip is different from the first embodiment in the shape of the corner 4. Since the corner 4 is formed with a corner cutting edge 8 which is rounded in an arc shape, this chip is mainly used by being mounted on a cutter for right-angle shoulder cutting.

[0021]

According to the present invention, the main cutting edge provided at the side ridge is formed in a curved shape and the rake angle in the axial direction is increased so that the cutting resistance is reduced without lowering the cutting edge strength and the sharpness is improved. Can be improved. Forming dimples on the rake face at predetermined intervals in the direction along the cutting edge reduces the cohesive force between the chips and the rake face and contributes to enhancing the above-described effects.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a perspective view of FIG. 1;

4A is an enlarged sectional view taken along line AA of FIG. 1, and FIG. 4B is an enlarged sectional view taken along line BB of FIG.

FIG. 5 is a diagram illustrating an axial rake angle.

FIG. 6 is a perspective view of a cutter body to which the tip according to the first embodiment of the present invention is attached.

FIG. 7 is a plan view showing a second embodiment of the present invention.

FIG. 8 is a side view of FIG. 7;

FIG. 9 is a perspective view of FIG. 7;

FIG. 10 is a plan view showing a conventional example.

FIG. 11 is a side view of FIG. 10;

FIG. 12 is a perspective view of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 chip body 3 rake face 4 corner 5 side ridge 6 front cutting edge 7 main cutting edge 10 dimple 12 inclined surface α inclination angle of main cutting edge γ clearance angle

Claims (1)

[Claims] 1. A rake face 3 having a curved surface that is concave inward in the chip thickness direction as a whole is formed on an upper surface of a chip body 1 having a polygonal flat plate shape having a clearance angle γ on an outer peripheral side surface 2.
At the intersection ridge formed by the outer peripheral side face 2 and the rake face 3, a front cutting edge 6 formed in a corner 4 and cut out in a chamfered shape and a main cutting edge 7 provided in a side ridge 5 are formed. Has been
In the indexable insert for a rotary tool in which a land 9 having a constant width is formed adjacent to each cutting edge 6 and 7 over the entire circumference, the rake face 3 is formed by cutting the cutting edge 6 and 7 from the cutting edge 6 and 7. The rake angle θ2 of the side ridge 5 and the corner 4
A relationship of θ1 <θ2 is formed between the rake angle θ1 and the dimple 10 on the rake face 3 with the cutting edge 6,
The lands 9 have a magnitude relationship of W2 <W1 between the land W1 of the front cutting edge 6 and the land width W2 of the main cutting edge 7. Further, the main cutting edge 7 has a curve gradually lowering at an inclination angle α of 3 to 15 ° from one corner 4 to an intermediate point with another corner 4 formed adjacently. A throw away tip characterized by being formed in a shape.