JPH08257837A - Throwaway tip for thread cutting - Google Patents

Abstract

PURPOSE: To curl a cutting chip into a coil shape so as to prevent extending the cutting chip entangled by forming irregularity, presenting a streaky shape toward a rake face from a boss surface to form a saw tooth shape in a plane view, in a tilted surface. CONSTITUTION: A step difference formed of a tilted surface 8 is provided between a boss surface 5 and a rake face 7, but this tilted surface 8 is formed not a simple plane but an irregular surface of presenting a streak shape from the boss surface toward the scrap face 7, to draw a pattern of saw tooth shape in a plane view. By action of a saw tooth tilt angle α formed by a tilted surface 8a corresponding to a cutting edge 6a and by a perpendicular 10 of a screw axial line, a cutting chip is discharged from the cutting edge 6a, to flow out on the rake face 7 in a direction almost orthogonal to this cutting edge, brought into contact with the tilted surface 8a and deformed. This deformation is such that the chip is receiving bending in a lateral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breaker shape of a throw-away insert for thread cutting used in turning.

[0002]

2. Description of the Related Art In order to improve the chip controllability of a throw-away insert for thread cutting used for turning, various breakers have been put into practical use. The most typical example is what is called a lead type breaker as shown in FIG. 6, in which a step is provided between the rake surface 7 and the boss surface 5, and the inclination angle of the inclined surface 8 forming the step and the screw The discharge direction and deformation of the chips are controlled by the inclination of the arrangement of the inclined surface 8 with respect to the axis and the distance from the cutting edge 6.

In the second conventional technique, as shown in FIG. 7, a projection 1 is formed on the rake face 7 of the throw-away tip shown in FIG.
It is a protrusion type breaker on which the ejected chips are strongly contacted with the protrusions 11 to promote the deformation of the chips. Further, FIG. 8 is a so-called dimple-shaped breaker, and attempts to control the chip discharge by utilizing the action of the chips being guided to the recess 13 arranged along the cutting edge 6. It is a thing. Both the protruding shape and the dimple shape aim to restrain the chips near the cutting edge, and most of them are used in combination with the lead shape.

[0004]

In thread cutting by turning, the chip thickness is reduced due to the small amount of one cut, and due to the special shape of the cutting edge forming a chevron, the chip is elongated. It is easy to get entangled and it is much more difficult to deal with chips than general turning. The above-mentioned lead type breaker has a poor chip restraining force, and extended chips may be entangled with a cutting tool, a work piece, or a tool rest of a lathe.

In the case of the protrusion-shaped or dimple-shaped breaker, since the protrusions and dimples are arranged in the vicinity of the cutting edge, the chip restraining force is increased, but these alone cannot cope with a wide range of cutting situations. Is used in combination with a lead type breaker.

The present invention has been made in view of the above situation, and further improves the chip discharging property by restricting and directing the chip outflow by a breaker shape. is there.

[0007]

In order to achieve the above-mentioned object, the present invention is a throw-away tip having a triangular flat plate shape, the corners of which are formed in a shape matching the screw thread. In a throwaway insert for thread cutting with a cutting edge, the cutting edge is retracted to a position lower than the boss surface, and the step between the cutting edge and the boss surface has an inclination that rises from the rake surface of the cutting edge to the boss surface. A surface is formed, and the inclined surface is provided with unevenness in the form of scratches extending from the boss surface toward the rake surface to form a sawtooth-shaped uneven surface in plan view.

In addition, a saw-tooth inclination angle α formed by the inclined surface on one side of the irregularities having a saw-tooth shape in plan view formed in this way and the perpendicular of the screw axis, and a cutting edge located on the feed direction side of the thread cutting The relationship with the flank angle θ formed by the vertical line of the screw axis is α ≦ θ. Further, the bottom ridgeline of the protrusion forms a protrusion on the rake face with a certain width maintained with respect to the cutting edge. The intervals are formed so as to be parallel or wide as the distance from the tip of the cutting edge increases.

[0009]

In the conventional lead type breaker, the inclined surface is arranged in a direction parallel to the axis of the screw, so that the force to deform the chips to the cutting edge side (front side) is reduced. On the other hand, in the present invention, the chip is in contact with the inclined surface on one side of the unevenness, and due to the action in the direction in which the inclined surface is facing, the chip bends toward the feed side (lateral side) and deforms. I will receive it. Furthermore, if one side of the unevenness is angled so as to be smaller than the flank angle of the cutting edge, the effect is more remarkable, and the chip receives a force in a direction away from the cutting edge, and when it is stretched indiscriminately and does not become entangled. At the same time, it has a regular curled shape and, depending on the cutting conditions, cuts into a moderate length.

The protrusions arranged near the cutting edge of the rake face
Excellent breaker effect is achieved by the same action as above for small cuts. In addition, by combining with the above-mentioned sloped surface with irregularities, even under the cutting situation where the chips will get over the protrusions, this chip surface will now provide good chip control. A breaker that can be applied to a wide range of cutting conditions is realized.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings.

1 to 3, a countersink 4 is formed at the center of a throw-away tip 1 in the shape of a triangular flat plate so as to penetrate from the upper surface 2 to the lower surface 3. The throw-away tip 1 is mounted on a tip seat provided on the thread cutting tool body, and then fixed with a countersunk screw inserted into the countersink hole 4. A flat surface around the countersink 4 on the upper surface 2 is a boss surface 5, and is located outside the boss surface 5.
Cutting edges are provided at the corners of the place. This cutting edge portion is located lower than the boss surface 5 on the lower surface 3 side, and is constituted by a cutting edge 6 having an outer edge thereof and a rake surface 7.
Since the cutting edge 6 is formed in a shape that matches the shape of the thread to be machined, the shape of the cutting edge 6 is directly transferred to the workpiece by cutting, and the thread is cut.

There is a step formed by an inclined surface 8 between the boss surface 5 and the rake surface 7, but the inclined surface 8 is not a mere flat surface, but a striation shape extending from the boss surface 5 toward the rake surface 7. The surface is uneven and exhibits a sawtooth pattern in a plan view. The details are shown in FIG.

In FIG. 3, the inclined surface 8 is arranged so as to be inclined by a lead angle β with respect to the parallel line 9 of the screw axis. Usually, the lead angle β is preferably in the range of 0 to 60 degrees, but in practice it is difficult to carry out the operation.
It is rare that they are set close to each other.

In the most general outer diameter thread cutting, the throw-away tip 1 is cut and fed to the left in the figure. When processing metric threads in such thread cutting,
The inclined surface 8 is arranged facing the front side of the cutting edge 6a located in the feeding direction. Even when the lead angle β is 60 degrees, which is the maximum, it is parallel to the cutting edge 6a. In other words, in the range where the lead angle β is 0 to 60 degrees,
The complementary angle of the lead angle β is perpendicular to the cutting edge 6a and the screw axis.
That is, it is not smaller than the flank angle θ formed by 0 and.

However, the uneven inclined surface 8 of the present invention has a function of substantially increasing the lead angle β even if the lead angle β is small. That is,
The inclined surface 8a corresponding to the cutting edge 6a and the perpendicular line 1 to the axis of the screw
By the action of the sawtooth inclination angle α formed by 0, the chips discharged from the cutting edge 6a and flowing out on the rake face 7 in a direction substantially orthogonal thereto are brought into contact with the inclined face 8a and deformed. The deformation is a deformation that undergoes lateral bending more than in the case of an inclined surface that is only flat. Sawtooth tilt angle α and flank angle θ
If the relation with α is less than or equal to θ,
As a result, the chip is subjected to a deforming force in the direction away from, and good chip ejection is performed.

Although the above is also effective in the radial infeed processing in which the cutting at the time of thread cutting is applied to both sides of the cutting edges 6a and 6b, in the flank infeed processing in which only one cutting edge 6a is cut. The effect is remarkable. Further, in the present embodiment, the uneven surface has a waveform that is one of the sawtooth shapes, but it may have an asymmetric sawtooth shape.

4 and 5 show another embodiment of the present invention, in which the same parts are designated by the same reference numerals. This throw-away tip 1 is obtained by adding a projection 11 on the rake face 7 to the one shown in FIG. Bottom ridgeline 1 of protrusion 11
2a and 12b are placed with a certain width on the cutting edges 6a and 6b, respectively, but the intervals thereof are formed to be parallel or wide as the distance from the tip of the cutting edge 6 increases.

The action of the width thus formed is the same as the action of the sawtooth inclination angle α described above, and the cutting edge 6
It deforms away from. Protrusion 11
Since it is close to the cutting edge 6, it exhibits an excellent breaker effect for cutting with a small cutting depth,
Exhibits an excellent breaker effect against chips that pass over the protrusion 11.

[0020]

According to the present invention, in thread cutting by turning, the chips are constrained by the uneven surface of the breaker and receive a force that flows away from the cutting edge. As a result, the chips are curled into a coil shape, and if good, they are cut into a certain length. The phenomenon of chip entanglement can be prevented, and moreover, preferable chip treatment can be performed over a wide range of cutting conditions.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

2A is a plan view and FIG. 2B is a front view.

FIG. 3 is an enlarged plan view of the cutting edge portion of FIG. 1.

FIG. 4 is a perspective view showing another embodiment of the present invention.

5A is a plan view and FIG. 5B is a front view.

FIG. 6 is an enlarged perspective view of a cutting edge portion showing a conventional example.

FIG. 7 is an enlarged perspective view of a cutting edge portion showing another embodiment of the related art.

FIG. 8 is an enlarged perspective view of a cutting edge portion showing another embodiment of the related art.

[Explanation of symbols]

 1 Throw-away tip 5 Boss surface 6 Cutting edge 7 Rake surface 8 Inclined surface 11 Protrusion α Saw tooth inclination angle β Lead angle θ Frank angle

Claims (3)

[Claims] Claim: What is claimed is: 1. A triangular flat plate is formed, and a cutting edge 6 is formed at a corner portion thereof in a shape matching a screw thread, and the cutting edge 6 is transferred to a workpiece to turn a screw. In the throw-away tip 1 for thread cutting, the cutting edge portion is lower than the boss surface 5, and the step between the cutting edge portion and the boss surface 5 is from the rake surface 7 of the cutting edge portion to the boss surface. 5 is formed by an inclined surface 8 which rises up to 5, and the inclined surface 8 is formed with a ridge-and-groove-like unevenness facing the rake surface 7 from the boss surface 5 and having a sawtooth shape in a plan view. Throw-away tip for thread cutting that is characterized by being. 2. A sawtooth inclination angle α formed by the inclined surface 8a on one side of the unevenness having a sawtooth shape in a plan view and a normal line 10 of the screw axis line, and a perpendicular line of the cutting edge 6a and the screw axis line located on the feed direction side of the thread cutting. The throw-away tip for thread cutting according to claim 1, wherein the relationship with the flank angle θ formed by 10 is α ≦ θ. 3. A projection 11 is placed on the rake face 7 of the cutting edge portion, and bottom ridge lines 12a and 12b thereof are provided.
Are placed with a certain width on the cutting edges 6a and 6b, respectively, and the intervals are formed to be parallel or wide as the distance from the tip of the thread of the cutting edge 6 increases. The throw-away tip for thread cutting according to claim 1 or 2.