JP2601429Y2 - Shank type rotary 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 shank type rotary cutting tool, and more particularly to an improvement of a rotary cutting tool held by a tool holder through a straight shank having a cylindrical shape.

[0002]

2. Description of the Related Art A rotary cutting tool having a cylindrical straight shank, which is gripped by the tool holder by the friction between the outer peripheral surface of the straight shank and the inner peripheral surface of the tool holder and driven to rotate, for example, End mills, drills, and the like have been frequently used. Such a rotary cutting tool,
In general, a high mounting accuracy is required for the main shaft in order to ensure sufficient processing accuracy, and the straight shank is usually cylindrically ground. For this reason, a sufficient frictional force is not always obtained, and if the cutting resistance increases due to the wear of the cutting edge due to use, a slip in the rotating direction or the axial direction occurs with the tool holder, and the machining accuracy is reduced. In some cases, tool breakage was caused. On the other hand, by forming a large number of grooves on the outer peripheral surface of the straight shank and bulging the inner peripheral surface of the holder into the grooves by elastic deformation, slip is prevented while maintaining the mounting accuracy of the straight shank. It has been proposed. 61-
The tools described in U.S. Pat. No. 1,753,212 and Japanese Utility Model Application Laid-Open No. 1-143310 are examples.

[0003]

However, when the groove is formed on the outer peripheral surface of the straight shank, stress concentration occurs in the groove due to the notch effect (notch effect), so that the breakage strength is reduced. was there.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a straight shank from slipping without deteriorating the mounting accuracy and breaking resistance.

[0005]

In order to achieve the above object, the present invention has a straight shank having a cylindrical shape, and the friction between the outer circumferential surface of the straight shank and the inner circumferential surface of the tool holder is increased. In the rotary cutting tool gripped by the tool holder and driven to rotate , the depth is substantially uniform over the entire outer peripheral surface of the straight shank, and the depth is equal to the diameter D of the opening.
On the other hand , a large number of recesses having a substantially partial spherical shape in the range of D / 6 to D / 3 are provided apart from each other.

[0006]

In such a shank type rotary cutting tool , since a large number of recesses are provided substantially uniformly over the entire outer peripheral surface of the straight shank, when the inner peripheral surface of the tool holder is pressed against the outer peripheral surface. The inner peripheral surface of the holder is slightly swelled into the recess by elastic deformation, and the swelling suppresses the slip between the straight shank and the tool holder. Because the contact area between the straight shank and the tool holder is reduced due to the presence of the dent, the surface pressure is increased by that amount, the oil film or the like attached to the surface is removed, and the friction coefficient is increased. Slip between the straight shank and the tool holder is suppressed.

On the other hand, the plurality of recesses are provided apart from each other, and each has a depth equal to the diameter of the opening.
Since D has a substantially partial spherical shape in the range of D / 6 to D / 3 with respect to D , the notch effect due to the dent is small,
Stress concentration is suppressed, and sufficient breakage strength is maintained.
In addition, due to the surface contact between the outer peripheral surface other than the recess of the straight shank and the inner peripheral surface of the tool holder, the mounting accuracy is maintained well.

[0008]

As described above, according to the shank type rotary cutting tool of the present invention, the slip between the tool holder and the straight shank is suppressed without lowering the mounting accuracy and the breakage strength. Deterioration of machining accuracy and tool breakage due to this can be satisfactorily avoided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing an end mill 10 as a shank type rotary cutting tool. The end mill 10 has a cylindrical straight shank 12 and a blade portion 14.
Is provided with an outer peripheral blade 16 and a bottom blade 18. The straight shank 12 is finished by cylindrical grinding in order to enhance the mounting accuracy, and a plurality of recesses 20 each having a substantially partial spherical shape are provided on the outer peripheral surface of the straight shank 12 so as to be separated from each other. These recesses 20 have substantially the same size and are substantially uniformly distributed over the entire outer peripheral surface. In the present embodiment, the diameter D of the opening of each recess 20 is about 1 to 3 mm, the depth is about D / 6 to D / 3, and the radius of curvature is 0.5 D to
It is about 0.9D and is formed by processing means such as milling or flat die rolling.

The end mill 10 is mounted on a main shaft of a milling machine or the like via, for example, a straight collet 22 shown in FIG. 2, and is driven to rotate about an axis to perform cutting. The straight collet 22 has a diameter-reducible cylindrical shape in which a plurality of slits 26 are formed from the flange 24 side. The straight collet 22 is inserted into a mounting hole of a chuck provided on a main shaft, and is reduced in diameter. The inner peripheral surface 28 is brought into close contact with the outer peripheral surface of the straight shank 12, and the friction between them grips the straight shank 12 so that it cannot rotate relatively and cannot come out. Straight collet 22
Constitutes a tool holder together with a chuck (not shown) for reducing the diameter.

Here, the end mill 10 of this embodiment is used.
Has a number of recesses 2 on the outer peripheral surface of the straight shank 12.
0, the straight collet 22 is reduced in diameter and pressed by the straight shank 12, so that the inner peripheral surface 28 of the straight collet 22 is slightly deformed into the recess 20 by elastic deformation as shown in FIG. Be swelled.
Due to this swelling, the relative movement between the straight shank 12 and the straight collet 22 is suppressed, and the slip of the straight shank 12 is prevented in combination with the friction of the surface contact portion. Since the contact area between the straight shank 12 and the straight collet 22 is reduced due to the presence of the recess 20,
The surface pressure is increased by that amount, the oil film or the like adhering to the surface is removed, and the friction coefficient is increased. In this respect, the slip of the straight shank 12 with respect to the straight collet 22 is also suppressed.

On the other hand, since the plurality of recesses 20 are provided apart from each other and each have a substantially partial spherical shape, the notch effect due to the recesses 20 is small, and stress concentration is suppressed and sufficient. High breaking resistance is maintained. In addition, since the outer peripheral surface of the straight shank 12 other than the recess 20 has high accuracy by cylindrical grinding finish, by the surface contact with the inner peripheral surface 28 of the straight collet 22,
The mounting accuracy with respect to the straight collet 22 and the main shaft is well maintained.

If the total area of the recess 20 is too large, the mounting accuracy is impaired. If the total area of the recess 20 is too small, a sufficient slip suppressing effect cannot be obtained. The ratio is desirably set within a range of about 1: 1 to 5: 1.

As described above, according to the end mill 10 of the present embodiment, the slip of the straight shank 12 with respect to the straight collet 22 is suppressed without lowering the mounting accuracy with respect to the main shaft and the breakage resistance, and the machining caused by the slip is suppressed. reduction and Engineering tools damage of accuracy is satisfactorily avoided.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in other forms.

[0016]

For example , in the recess 20 of the above embodiment, the circumferential and axial positions are regularly arranged on the outer peripheral surface of the straight shank 12, but the intervals in the circumferential and axial directions are irregular. May be arranged as follows.

In the above-described embodiment, the case where the present invention is applied to the end mill 10 has been described. However, the present invention can be similarly applied to other shank type rotary cutting tools such as a drill and a mill having a straight shank.

Further, in the above-described embodiment, the case of attaching to the main shaft via the straight collet 22 has been described. However, other types of tool holders for gripping the outer peripheral surface of the straight shank 12 may be used.

Although not specifically exemplified, the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a front view of an end mill according to an embodiment of the present invention.

FIG. 2 is a view showing a state in which the end mill of FIG. 1 is fitted to a straight collet.

FIG. 3 is an enlarged cross-sectional view showing an engagement form between a recess provided in a straight shank of an end mill and an inner peripheral surface of a straight collet.

[Explanation of symbols]

 10: end mill (shank type rotary cutting tool) 12: straight shank 20: recess 22: straight collet (tool holder) 28: inner peripheral surface

Continuation of the front page (56) References JP-A-58-90410 (JP, A) JP-A-61-175312 (JP, U) JP-A-62-39905 (JP, U) JP-A-63-186537 (JP) , U) Japanese Utility Model Showa 58-143107 (JP, U) Japanese Utility Model Showa 60-127809 (JP, U) Japanese Utility Model Showa 57-96734 (JP, U) Japanese Patent Publication No. 48-27668 (JP, B1) Japanese Utility Model Showa 56-22966 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23B 51/00 B23C 5/10 B23B 31/08 B23B 31/20 B23G 5/06

Claims (1)

(57) [Scope of request for utility model registration] 1. A rotary cutting tool having a straight shank having a cylindrical shape, wherein the rotary cutting tool is gripped by the tool holder and driven to rotate by friction between an outer peripheral surface of the straight shank and an inner peripheral surface of the tool holder. Depth almost uniformly over the entire outer peripheral surface of the straight shank
Is in the range of D / 6 to D / 3 with respect to the diameter D of the opening.
1. A shank type rotary cutting tool comprising: a plurality of recesses having a substantially partial spherical shape which are spaced apart from each other.