JP3415944B2 - Grooved cutting tool - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rod-shaped cutting tool mainly used for cutting the inner surface of a small-diameter hole, and a grooved cutting tool in which a groove along the axial direction of the shank is formed at the tip of the shank.

[0002]

2. Description of the Related Art A rod-shaped cutting tool equipped with a throw-away tip (hereinafter simply referred to as a tip) on the tip side is
It is widely used for various cutting purposes, but chatter vibration often occurs when the inner surface of a small-diameter hole is cut using such a rod-shaped cutting tool. When chattering vibrations occur, the machined surface deteriorates and the life of the cutting edge is significantly shortened. When the machined surface is a sliding surface, the amount of initial wear increases due to deterioration of the machined surface, and it takes a long time until the machine can operate normally.

The chatter vibration is generated when a minute vibration generated between the member to be cut and the cutting edge in the cutting process is transmitted to the shank and resonates at the natural frequency of the shank to increase the vibration of the cutting edge.

One of the measures for preventing chatter vibration is to increase the thickness of the shank to increase the rigidity of the tool.
If an attempt is made to increase the rigidity of the shank with the above-described cutting tool, the diameter of the shank becomes large and it becomes impossible to cut the inner surface of the small diameter hole. In addition, the tip attached to the tip of the shank is made of a hard material such as cemented carbide and ceramics, and has hardness that can cut almost all materials, but it has poor toughness and is brittle, so the cutting edge during the cutting process. When a shock load is applied to the shank, increasing the rigidity of the shank rather increases the shock applied to the cutting edge, and the cutting edge of the tip cannot withstand this and is broken.

Although there is a measure to prevent the resonance of the shank by incorporating a damping member inside the shank (Japanese Patent Laid-Open No. 3-86404, etc.), the strength of the shank is reduced by providing a space for incorporating the damping member. Therefore, it is difficult to apply it to an inner surface cutting tool having a small diameter hole with a shank diameter of about 15 mm.

It is known as another measure for preventing chattering vibration that a groove is formed on the shank or its holding portion to increase elasticity and suppress shock and vibration. Japanese Utility Model Publication No. 57-9403, Japanese Utility Model Publication No. 3-
No. 82104 is disclosed.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The technique disclosed in Japanese Patent No. 403, as shown in FIG.
A groove 13 composed of a prismatic opening 13a and a cylindrical opening 13b is formed at the side end of the shank 11 to impart elasticity and prevent chattering vibrations on the cutting edge 12. However, since the groove 13 is formed orthogonally to the acting direction of the load, the bending rigidity with respect to the load decreases, and as a result, the shank 11 bends at the small-diameter portion 14 as the load increases and is machined. There is a risk of degrading accuracy.

Further, in the technique disclosed in Japanese Utility Model Laid-Open No. 3-82104, as shown in FIG. 8, a tool rest mounting portion 24 is integrally formed on a side portion of a cutting tool portion 23 composed of a cutting edge 21 and a shank 22. And a long through slit 25 along the axis of the shank 22 is formed between the shank 22 and the tool rest mounting portion 24 to block the propagation of vibration to the tool rest 26 and to prevent chatter vibration of the cutting edge 21. Although it is to prevent it, it cannot be applied to tools for inner surface cutting of small diameter holes because of the special shape of the tool.

The present invention provides a grooved cutting tool capable of maintaining flexural rigidity in the load direction even when a groove is formed at the tip of the shank, preventing chatter vibrations, and mitigating the impact acting on the tip. The purpose is to provide.

[0010]

A cutting tool according to the present invention is a rod-shaped inner surface cutting in which a tip is mounted on a tip seat provided at the tip of the upper surface of the tip of a shank with a cutting edge protruding laterally. in the tool, the distal end portion of said shank
At the center of the upper surface, the tip is located closer to the base than the tip seat and
It is characterized by forming a groove parallel to the axial direction of the shank . Due to this groove, the vibration transmitted from the cutting edge of the tip to the main body of the shank is diversified at the tip of the shank, and mutual resonance of these vibrations suppresses resonance of the shank. That is, the vibration of the cutting edge propagates in the tip portion of the shank by being divided into a path that travels through the tip mounting side, a path that travels through the groove on the opposite side, and a path that goes through the bottom of the groove and travels on the opposite side. Due to the difference in vibration characteristics based on the difference in the cross-sectional shape and cross-sectional area of the path, and the difference in the length of the propagation path, the phase of vibration is deviated, and these interfere with each other in the main body of the shank to attenuate, resulting in
Resonance of the shank is suppressed and chatter vibration is prevented. Further, by forming the groove, the elasticity of the tip portion of the shank is increased and the impact acting on the cutting edge is mitigated. Also, the tip of the shank
The upper surface of the part is almost straight in the direction of the load applied by cutting resistance.
Since it is a surface that intersects, it is negative by forming a groove here.
Flexural rigidity for loads is maintained. In addition, near the tip of the groove
Because the end of the needle is located closer to the base than the tip seat,
Therefore, the thickness decrease due to the formation of the groove below the tip seat
Since it does not occur, the strength of the tip seat is maintained. Of the groove
The end near the base end is positioned in front of the tool grip of the machine tool.
As long as it is placed, it does not matter even if it extends to the main part of the shank.
I can't.

According to a second aspect of the present invention, the groove is the
It is characterized in that it is a groove formed vertically on the upper surface of the shank.
I am doing.

According to a third aspect of the present invention, the groove has a depth.
Is characterized by uneven grooves . like this
A large groove maintains the strength of the shank tip.
The propagation path of vibrations that pass through the points and the bottom of the groove.
The structure is more effective in terms of diversifying the road.

The invention according to claim 4 is characterized in that the groove is a plurality of grooves formed intermittently in the axial direction of the shank. The intermittently formed groove reduces the flexural rigidity of the tip portion of the shank less than that of the continuous groove, and diversifies the propagation path of the vibration transmitted from the tip of the tip to the main body of the shank.

According to the invention of claim 5, in addition to the groove,
Position on the underside of the shank tip.
It is characterized by further forming a groove . like this
To, by providing a plurality of grooves in the upper and lower surfaces of the shank tip by shifting the position, vibration propagation paths traveling slip through the bottom of the groove is more diversified, further improved resonance suppressing effect of the shank by these mutual interference To do.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

The grooved cutting tool illustrated in this embodiment has a shank body portion having a diameter of 15 mm and an overall length of 180 mm.
Is a tool for inner surface cutting of a small diameter hole, which is mainly used as a boring tool or a single-edged end mill. As shown in FIGS. 1 and 2, a tip seat 3 is provided on the top end of a tip portion 2 of a shank 1, and a flat surface is provided. A parallelogram-shaped tip 4 is detachably fixed to a tip seat 3 with a screw 6 in a state where one of the sharpened cutting edges 5 slightly protrudes from a side surface 2a of a tip portion 2 of a shank.

The portion of the top surface of the tip portion 2 of the shank near the tip is a flat rake face along the top surface of the tip 4, and the cutting edge 5 of the tip 4 is located at substantially the same height as the central axis of the shank 1. is doing. The base end portion of the shank tip portion 2 is formed into an arcuate inclined surface that rises toward the shank body portion 7, and is also formed into a slightly concave surface in the direction transverse to the axis of the shank 1, Of the shank is maintained, the strength of the tip portion 2 of the shank is maintained, and the chips are smoothly discharged.

As described above, since the shank tip portion 2 is formed by cutting out the upper half of the shank body portion 7, it is more elastic than the shank body portion 7. Due to the simple cross section, when the cutting resistance increases, the vibration generated at the cutting edge 5 of the tip may be transmitted as it is to the main body portion 7 of the shank and the entire shank 1 may resonate to cause chatter vibration. However, in the grooved cutting tool of the present invention, since the groove 8 along the axial direction of the shank 1 is formed in the center of the upper surface of the tip portion 2 of the shank, the vibration transmitted from the cutting edge 5 to the main body portion 7 of the shank is shank. Are diversified at the tip portion 2 of the shank 1 and interfere with each other to prevent resonance of the shank 1. That is, in the tip portion 2 of the shank, the vibration of the cutting edge 5 passes through the cutting edge side 2a, the path passing through the cutting edge 5 and the opposite side 2b of the groove 8, and passes through the bottom of the groove 8 from the 2a side to the 2b side. The vibration is divided into different paths, and the vibration characteristics are different depending on the cross-sectional shape and cross-sectional area of each propagation path, as well as the phase difference of the vibration due to the difference in the length of each propagation path. Damping, and as a result, resonance of the shank 1 is suppressed and chatter vibration is prevented. Further, the formation of the groove 8 increases the elasticity of the tip portion 2 of the shank, so that the cutting edge 5
The impact applied to is reduced.

Since the groove 8 is formed on the upper surface of the tip portion 2 of the shank which is substantially orthogonal to the acting direction of the load,
The bending rigidity of the tip portion 2 of the shank is maintained.

Since the end of the groove 8 near the tip is located closer to the base than the tip seat 3, the strength of the tip seat 3 is maintained even if the groove 8 is formed. The rear end of the groove 8 is
As long as it is located in front of the tool gripping portion (not shown) of the machine tool, it may extend to the main body portion 7 of the shank.

The groove 8 may be a plurality of grooves 8a formed intermittently along the axial direction of the shank 1, as shown in FIG. The intermittently formed groove reduces the decrease in bending rigidity of the tip portion 2 of the shank as compared with the continuous groove, and makes the propagation paths of the vibration transmitted to the main body portion 7 of the shank more diversified.

Further, as shown in FIG. 5, it is possible to form a plurality of offset grooves 8b on both upper and lower surfaces of the tip portion 2 of the shank. In this case, the propagation paths of the vibration passing through the bottom of the groove 8b are further diversified, and the vibration damping effect due to mutual interference is further improved.

The depth of the groove 8 does not have to be uniform, and is not shown in FIG.
As described above, the groove 8 having a non-uniform depth is more effective in that the strength of the tip portion 2 of the shank is maintained and that the propagation path of the vibration that passes through the bottom of the groove 8 is diversified. Target. Further, as shown in FIG. 6, the tip portion 2 of the shank may be a through groove 8c penetrating up and down. In this case, vibration is completely blocked at a portion separated by the through groove 8c, and thus the vibration is prevented. It is possible to more reliably separate the propagation paths of.

In the above, as an example of the groove 8, a straight groove formed parallel to the axis of the shank 1 and perpendicular to the upper surface of the tip portion 2 of the shank has been described, but the tip portion of the shank accompanying the formation of the groove 8 is described. In order to further reduce the decrease in bending rigidity of No. 2, the groove 8 is displaced from the axis of the shank 1 so that the end nearer the tip is directed toward the tip 5 of the tip, or only the end nearer the tip is It is also possible to make a curved groove directed in the direction of the cutting edge 5. The groove 8 can also be formed by inclining to the cutting edge 5 side.

[0025]

As described above, according to the grooved cutting tool of the present invention, by forming the groove along the axial direction of the shank at the tip portion of the shank, the vibration generated in the cutting process is shank. Are diversified and propagated at the tip of the shank, and in the process vibrations that are out of phase interfere with each other to be damped, and chatter vibration is prevented because the resonance of the shank is suppressed, and the elasticity of the tip of the shank is formed by forming the groove. Since the property is increased and the impact is relieved, the chip is prevented from being broken.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a grooved cutting tool of the present invention.

FIG. 2 is a side view of the same.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a plan view of a shank tip portion showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a shank tip portion according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of a shank tip portion according to another embodiment of the present invention.

FIG. 7 is a side view showing a conventional technique of a grooved cutting tool.

FIG. 8 is a plan view showing another conventional technique of a grooved cutting tool.

[Explanation of symbols]

1 ... Shank 2 ... shank tip 2a, 2b ... Side surface of shank tip 3 ... Chip seat 4 ... Chip 5 ... Cutting edge 7 ... shank body 8, 8a, 8b, 8c ... Groove

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23B 29/02 B23B 27/00

Claims (5)

(57) [Claims] To 1. A tip seat provided on the upper surface distal of the distal end portion of the shank, in a rod-like inner surface cutting tool equipped with the chip in a state of protruding cutting edge laterally, the center of the upper surface of the distal end portion of said shank, Tip is tip seat
Located closer to the base end and parallel to the shank axial direction,
A grooved cutting tool having grooves formed therein. 2. The groove is perpendicular to the top surface of the shank.
The groove according to claim 1, wherein the groove is formed.
Cutting tools. 3. The groove is a groove having an uneven depth.
The grooved cutting tool according to claim 1, wherein: 4. The cutting tool according to claim 1, wherein the groove is a plurality of grooves formed intermittently in the axial direction of the shank. 5. In addition to the groove, the position is shifted from the groove.
The cutting tool according to claim 1, wherein a groove is further formed on the lower surface of the tip portion of the shank .