JPH05301106A - Spindle for machine tool and tool holder - Google Patents

Abstract

PURPOSE:To align accurately and mount a tool holder for finishing work and the like to a spindle, even if the tapered hole of the spindle in which the shank part at the tail end of a tool holder for roughing out and the like is fitted is worn. CONSTITUTION:A mouth part 11 which has a larger diameter than the bore of an extended tapered hole 10 is formed on the spindle end side of the tapered hole 10. The mouth part 11 is tapered with on angle smaller than the tapered angle of the tapered hole 10. A guide tapered part 24 which is loosely inserted in the tapered hole 10 is formed at the shank part 22 of a fool holder and tapered part 23 formed at the base end of the shank part 22 is fitted in the mouth part 11 in such a state of roughly aligning the tool holder 2 with the spindle 1 by the guide tapered, part 24 so that the tool holder 2 is aligned with the spindle 1. A flange 21 of the holder 2 is closely stuck to the end face of the spindle so as to prevent inclination of the tool holder 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle mainly used for a tool exchange type machine tool and a tool holder adapted to the spindle.

[0002]

2. Description of the Related Art Conventionally, according to Japanese Patent Laid-Open No. 62-246448, there is provided a tool changing means for gripping a tool holder on a flange formed on the tool holder, and a shank portion extending the tool holder to the tail of the flange by the means. A tool exchange type machine tool is known in which a tool is exchanged by inserting it into a taper hole of a spindle. With this, the taper hole of the spindle is opened at the tip end surface of the spindle with the same taper angle, and the shank portion of the tool holder is fitted into the taper hole leaving a root portion near the flange.

[0003]

The taper angle of the tapered hole formed in the spindle of the tool exchange type machine tool is set to a predetermined value standardized in consideration of the centripetal performance of the tool holder and the detachability of the shank portion. However, if the tool holder is replaced more often, the inner peripheral surface of the tapered hole will wear,
There is a problem that the reproducibility of the centering accuracy deteriorates and it becomes difficult to secure accuracy during finishing such as fine boring. In view of the above points, the present invention allows a tool holder for rough machining and a tool holder for finish machining to be mounted on the spindle in different forms, so that even if wear occurs in the taper hole of the spindle, It is an object of the present invention to provide a spindle capable of ensuring the positional accuracy of the tool holder with respect to the spindle and a tool holder adapted to the spindle.

[0004]

SUMMARY OF THE INVENTION The above object is to provide a spindle by forming a tapered opening at a portion of the tapered hole on the spindle tip side, the opening having a diameter larger than the diameter of the extended tapered hole. On the other hand, the tool holder is provided with a flange that comes into close contact with the tip surface of the spindle, and the shank portion extending from the flange to the tail side is loosely inserted into the taper hole and the taper portion that is fitted into the mouth hole of the spindle. This can be achieved by forming the guide taper portion.

[0005]

When the tool holder is mounted on the spindle, the guide taper portion is first inserted into the taper hole so that the tool holder is approximately centered on the spindle. In this state, the taper portion is fitted into the mouth portion. The tool holder is finally centered and held on the spindle, and at the same time, the flange comes into close contact with the spindle tip surface. In this case, since the axial length of the mouth portion cannot be made too long, the function of suppressing the inclination of the tool holder is deteriorated, but the inclination of the tool holder is prevented because the tool holder comes into close contact with the spindle tip surface at the flange.
Thus, the tool holder for rough machining etc., which does not require the positional accuracy with respect to the spindle to the left, is the same as the conventional one that fits into the tapered hole in the shank portion, and the tool holder for finish machining is constructed as described above. As a result, the positional accuracy of the tool holder for finish machining with respect to the spindle can be ensured even when the tapered hole is worn, and highly accurate machining can be performed. If the taper angle of the base is large, it will be difficult to push the taper part further with a tight margin after the outer peripheral surface of the taper part contacts the inner peripheral surface of the base part, and the flange will not contact the spindle tip surface. The flange floats when the taper part fits in the base part before contact, and the flange contacts the spindle tip surface before the taper part fits in the base part, and further pushing is restricted. In this case, the centering accuracy cannot be obtained, so that it is necessary to control the dimensions of the spindle and the tool holder with high accuracy. If the taper angle is small, it will be easier to push the taper part into the mouth part with a tight margin, and even if the taper part fits in the mouth part before the flange contacts the spindle tip surface, the taper part will be pushed in further and the flange part Can be closely attached to the tip surface of the spindle. Therefore, it is desirable that the taper angle of the mouth portion be smaller than the taper angle of the tapered hole.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, 1 is a spindle and 2 is a tool holder for finishing such as fine boring.
The spindle 1 has a tapered hole 10 that expands in the forward direction.
Is formed, and at the tip end side of the tapered hole 10, a base portion 11 having a diameter larger than the diameter of the extended tapered hole 10 is formed.
Formed. The mouth portion 11 is also tapered, but its taper angle is set to a small value of about 4 °, whereas that of the tapered hole 10 is set to a large value of about 16 °. The tool holder 2 has a tool bit 20 attached to the tip thereof, a flange 21 serving as a gripping point when a tool is changed, and a shank portion 22 formed at the tail end in the middle, and the shank portion 22 has a flange. A tapered portion 23 that fits into the mouth portion 11 is formed adjacent to the guide portion 21, and two guide taper portions 24, which are two stages before and after being loosely inserted into the tapered hole 10, are formed at the tail of the tapered portion 23.
The flange 21 is formed so as to be in close contact with the tip end surface 12 of the spindle 1 in a state where the tapered portion 23 is fitted in the mouth portion 11, and thus the tool holder 2 has the tapered portion 23.
Due to the fitting into the mouth portion 11 and the close contact of the flange 21 with the spindle front end surface 12, the spindle 1 is accurately held without misalignment or inclination. In the figure, reference numeral 25 denotes a pull stud projectingly provided at the tail end of the shank portion 22, and a draw bar (not shown) inserted in the spindle 1 is engaged with the pull stud 25 to push and pull the shank portion 22.

By the way, a tool holder for drilling or roughing does not require a high degree of centering accuracy with respect to the spindle 1, but on the other hand, it requires a large fitting allowance for the spindle 1 because the processing load becomes large. Therefore, as shown in FIG. 2, a tool holder 2'of this type is fitted into the tapered hole 10 of the spindle 1 at the shank portion 22 'of the tail end having a single taper shape as in the conventional case. In this case, the flange 21 ′ floats from the tip surface 12 of the spindle 1 so as not to restrict the fitting of the shank portion 22 ′ into the tapered hole 10. The tool holder 2'has a drill 20 'at the tip.
Is a holder for drilling, which has a pull stud 25 'protruding from the tail end of the shank portion 22', like the holder.

[0008]

As is apparent from the above description, according to the present invention, the shank portion can be fitted in the tapered hole to mount the tool holder for rough machining and the tapered hole can be worn. A tool holder for finishing or the like can be accurately centered on the spindle and can be mounted so as not to cause an inclination, which has the effect of performing high-precision machining.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mounted state of a spindle and a tool holder according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a conventional tool holder is mounted on the spindle of the present invention.

[Explanation of symbols]

 1 spindle 2 tool holder 10 taper hole 11 mouth 12 spindle tip 21 flange 22 shank 23 taper 24 guide taper

Claims (3)

[Claims] 1. A spindle having a taper hole for receiving a shank portion of a tail end of a tool holder, wherein a portion of the taper hole on the spindle tip side has a tapered diameter larger than a diameter of the extended taper hole. A spindle for machine tools, characterized by having a hole formed therein. 2. The spindle for machine tools according to claim 1, wherein the taper angle of the mouth hole is smaller than the taper angle of the taper hole. 3. A tool holder mounted on the spindle for machine tools according to claim 1, further comprising a flange that comes into close contact with a tip end surface of the spindle, and a shank portion extending from the flange to the tail of the spindle. A tool holder characterized in that a taper portion that fits into the mouth hole and a guide taper portion that is loosely inserted into the taper hole are formed.