JPH03213202A - Spindle device of cutting machine - Google Patents

Abstract

PURPOSE:To suppress vibration without performing highly accurate work by fit-mounting a ring plate, in which its internal and external peripheral surfaces touch the periphery of a drover and its shaft hole respectively and provided with a vibration-absorbing transmitting member having elasticity in the diametric direction, to the drover, between two sheets of belleville springs having their surfaces adjacent to each other. CONSTITUTION:A ring plate 18 transmits urging force in the axial direction between belleville springs 9 on both sides and supports O rings 19, 20 in such a manner as they can extend/contract in the diametric direction and slide in the axial direction. Since this ring plate 18 is provided in the central part of each belleville spring 9, the O rings 19, 20 act to serve as a damper for which a vibration frequency f1 with a shaft length L in a half wave length containing a vibration frequency f2 of an integral system consisting of the belleville spring 9 and a drover 12 is set to the center vibration absorbing frequency, and as a result, resonance with the frequency f1 serving as the resonance frequency is substantially reduced. Vibration can be reduced without increasing accuracy of internal and external diameters of the ring plate 18 because of pressure of the O rings 19, 20.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a spindle device for a cutting device.

[Conventional technology] FIG. 3 shows a main spindle device of a conventional cutting device.

This main shaft device has a main shaft 2 having a shaft hole 8,
The tip of the shaft hole 8 is a wide tapered hole 7 that slidably holds the tool 6. Inside the shaft hole 8, there is a drawbar 12.
is inserted, and both ends of the drawbar 12 are held by the shaft hole 8 so as to be slidable in the axial direction. Drawbar 1
2 has multiple disc springs 9 F! It is equipped with a plate and a plate.
urges the drawbar 12 in the drawing direction.

The collet 11 provided at the tip of the drawbar 12 grips the pull stud 6b provided at the rear end of the tool 6, and the drawbar 12 is moved in the tool clamping direction (rightward in FIG. 3) by the elastic force of the book spring 9. ), the main shaft 2
The taper portion 6a of the tool 6 is fitted into the taper hole 7, and the tool 6 is clamped to the main shaft 2.

[Problems to be Solved by the Invention] In the spindle device of a cutting device that performs heavy cutting such as milling, a large pulling force is applied to the tool 6 in the axial direction of the spindle 2, and the tool 6 is held against this pulling force. In order to do this, a large number of disc springs 9 are fitted into the drawbar 12.

However, in order to fit a large number of disc springs 9 onto the drawbar 12, it is necessary to increase the axial length of the drawbar 12. However, since the drawbar 12 rotates at high speed, the increase in the axial length causes the drawbar 12 to The natural frequency of the spindle 2 decreases and approaches the rotational speed of the main shaft 2, and resonance may occur. For this reason, it is necessary to operate the spindle device below a critical speed (rotational speed that causes resonance), which limits the cutting ability.

Furthermore, when the axial length of the drawbar 12 increases, vibration of the drawbar 12 increases even if the speed is below the above-mentioned critical speed, which deteriorates machining accuracy.

The present invention was made in view of the above problems, and has a high resonance speed regardless of an increase in the axial length of the drawbar, and
The problem to be solved is to provide a spindle device for a cutting device that can reduce drawbar vibration and has a simple configuration.

[Means for Solving Problem 11] The main shaft device for cutting a position of the present invention has a shaft hole, and the tip of the shaft hole is a wide tapered hole that slidably holds a tool. a main shaft, a drawbar for tool retraction which is inserted into the shaft hole and whose ends are slidably held by the shaft hole in the axial direction; A main shaft device of a cutting device including a plurality of biasing disc springs, which is fitted into the drawbar so as to be movable in the axial direction, and whose ends individually abut the two adjacent disc springs, and whose inner and outer circumferential surfaces The present invention is characterized in that it includes a vibration absorbing and transmitting member that comes into contact with the outer circumferential surface of the drawbar and the shaft hole, and has elasticity in the radial direction.

This vibration absorbing and transmitting member can be composed of a plurality of parts. For example, a radial direction consisting of an axially movable biasing force transmitting member that transmits the elastic biasing force between adjacent disc springs in the axial direction, and an O-ring fitted to the inner and outer circumferential surfaces of this elastic biasing force transmitting member. It can be configured with a vibration absorbing member.

[Function] The vibration absorbing and transmitting member has elasticity in the radial direction, and its inner and outer circumferential surfaces are in contact with the outer circumferential surface and shaft hole of the drawbar, so that it absorbs vibrations in the middle part of the drawbar whose both ends are supported by the main shaft. (vibration absorption).

In addition, the vibration absorbing and transmitting member is fitted onto the drawbar so as to be movable in the axial direction, and both end surfaces individually contact two adjacent disc springs, so that the elastic biasing force is transmitted between the disc springs on both sides. .

Therefore, the vibration of the drawbar is reduced without interfering with the action of each disc spring.

r Example] An embodiment of the present invention is shown in FIG.

The main shaft 8 of this cutting device includes a main shaft 2 having a shaft hole 8;
Drawbar 12 inserted into shaft hole 8, Drawbar 12
1llll! It has a plurality of disc springs 9 installed therein, a biasing force transmitting member constituting the vibration absorbing transmitting member 18 in the present invention, and O-rings 19 and 20.

The explanation will be given below.

Six bearings 4 are fitted between the shaft hole 51 at both ends of the housing 50 and the main shaft 2 passing through the shaft hole 51, with four bearings 4 on the front side and two bearings 4 on the rear side. A sleeve 52 for maintaining the bearing spacing is interposed between the two.

The main shaft 2 is connected to the motor (
(not shown).

A shaft hole 8 extends through the main shaft 2 in the axial direction, and a wide tapered hole 7 is formed at the tip of the shaft hole 8. Also,
A portion of the shaft hole 8 on the tapered hole 7 side is formed to have a slightly smaller diameter, and as a result, a ring-shaped step 8a is formed in the shaft hole 8 near the taper hole 7.

The tapered hole 7 has a tapered portion 6a of the tool 6 to be clamped.
are fitted, and the pull stud 6b at the rear end of the tool 6 is clamped by the collet 11.

A small hole is provided axially through the center of the rear end wall 11C of the collet 11, and a plurality of elastic walls 11a extend forward from the outer peripheral edge of the rear end wall 11C in a direction parallel to the axis. The elastic wall 11a is formed to be elastically deformable in the radial direction using the rear end wall 11c as a fulcrum, and an engaging portion 11b for engaging the pull stud 6b projects in the radial direction at the tip end of the elastic wall 11a. It is set up.

The collet 11 is held slidably in the axial direction in a holder 10 having a cylindrical shape with an open end and a bottom. When the pull stud 6b is gripped, the engaging portion 11b of the collet 11 is inserted into the inner peripheral surface of the holder 10. is in contact with. Therefore, since the engaging portion 11b cannot expand radially outward, the pull stud 6b will not separate from the engaging portion 11b.

The holder 10 is embedded in the shaft hole 8 near the tapered hole 7, and the outer peripheral edge of the front end of the holder 10 is in contact with the step 8a. A small hole is also provided in the center of the rear end wall of the holder 10 in the axial direction.

A long rod-shaped drawbar 12 for clamping the tool 6 via a collet 11 is inserted into the shaft hole 8.
The tip of the drawbar 12 passes through the small hole in the rear end wall of the holder 10 and the small hole in the rear end wall of the collet 11, reaches the inside of the collet 11, and is connected to the collet 11 by a nut (not shown). .

A plurality of disc springs 9 are fitted in the shaft hole 8 for applying a tensile force in the backward direction to the drawbar 12,
The disc spring 9 at the tip is locked to the rear end wall of the holder 10, and the disc spring 9 at the rear end is connected to a cylindrical shifter (movable member) 17.
is fixed to the front end wall of the

A shifter (movable member) 17 having a cylindrical shape with a hole is fitted into the rear end of the shaft hole 8 of the main shaft 2 so as to be slidable in the axial direction, and the rear end of the drawbar 12 is fitted into the center of the shifter 17 in the axial direction. It is inserted through a small hole in the.

A nut 14 is screwed onto the rear end of the drawbar 12.
However, by adjusting the axial position of the shifter 17,
The biasing force of the disc spring 9 applied to the drawbar 12 is determined.

When removing the pull stud 6b from the engaging portion 11b of the collet 11, press the drawbar 12 in the forward direction to move the collet 11 along with the drawbar 12 on the main axis to a position where the engaging portion 11b can expand outward. Move it forward to the tip side of 2. When the engaging portion 11b of the collet 11 is moved forward from the open end of the holder 10 toward the tapered hole 7 side, the engaging portion 11b
1b expands outwards and the pull stud 6b can be removed.

Hereinafter, the characteristic parts of the present invention will be explained.

A wheel plate 18, which constitutes a biasing force transmitting member in the present invention, is interposed in the middle of a large number of disk springs 9 arranged in the axial direction. It is fitted freely. O-rings 19 and 20 constituting the radial vibration absorbing member in the present invention are attached to the inner and outer circumferential surfaces of the ring plate 18.
is fitted. These ring plates 18 and O-rings 19.
20 constitutes a vibration absorbing and transmitting member as used in the present invention.

The functions of the ring plate 18 and O-rings 19 and 20 of this embodiment will be explained below. However, there is a small clearance between the outer diameter of the drawbar 12 and the inner diameter of the disc spring 9, and a clearance is also provided between the outer diameter of the disc spring 9 and the shaft hole 8.

The ring plate 18 transmits the biasing force in the axial direction between the disk springs 9 on both sides, and supports the O-rings 19 and 20 so as to be expandable and contractible in the radial direction and slidable in the axial direction.

The O-rings 19 and 20 reduce the radial excitation force transmitted from the drawbar 12 and disc spring 9, thereby reducing their vibrations.

To explain in detail, in this embodiment, since the O-rings 19 and 20 are provided at the center of each disc spring 9, the 0-rings 19 and 20 have a vibration frequency f1 whose axial length is half a wavelength (and a vibration frequency f1 between the disc springs 9 and the drawbar). -12) acts as a damper with a central vibration absorption frequency of f2, and as a result,
Resonance with frequency f1 as the resonant frequency is significantly reduced.

What is important is that the presence of the O-rings 19 and 20 makes it possible to reduce the vibration of the drawbar 12 without increasing the accuracy of the inner and outer diameters of the ring plate 18.

Of course, it is also possible to employ a radial vibration absorbing member with a diameter of 19.20.

It is also possible to coat the ring plate 18 with a vibration absorbing material, and the collar 18 and O-rings 19, 20 may be installed at multiple locations in the axial direction.

In addition, when transmitting the rotational output to the main shaft 2, it was done via the power transmission component 3 fixed to the main shaft 2, but there is also a method of rotating the main shaft 2 with a built-in motor, or a method of directly connecting the main power source and the main shaft 2. Alternatively, the main shaft 2 may be rotated.

In order to grasp the pull stud 6b of the tool 6 (a collet 11 is provided at the tip of the dropper 12, the pull stud 6b is grasped by expanding and contracting a plurality of steel balls in the radial direction as the drawbar 12 moves forward and backward). You may also do so.

[Effects of the Invention] As explained above, the main spindle device of the cutting device of the present invention has the following features:
Fitted into the drawbar so as to be movable in the axial direction, both end surfaces individually contact two adjacent disc springs, inner and outer peripheral surfaces contact the outer peripheral surface of the drawbar and the shaft hole, and have elasticity in the radial direction. Since it is equipped with a vibration absorbing and transmitting member, it suppresses and absorbs the vibration of the main shaft and enables the main shaft to operate at higher speeds without requiring high-precision machining or increasing the number of vibration holes. That is, both the integral resonance of the drawbar and the disc spring and the independent resonance of the drawbar can be suppressed, without impairing the original function of the spindle device.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a main shaft device of a cutting device according to the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof. FIG. 3 is a sectional view showing an example of a conventional spindle device. 2...Main shaft 7...Tapered hole 8...Shaft hole 9...Disc spring 12...Drawbar 18...Ring plate (vibration absorption and transmission member)

Claims (1)

[Scope of Claims] A main shaft having a shaft hole, the tip of which is a wide tapered hole that slidably holds a tool; In a main shaft device of a cutting device, the main shaft device includes a draw bar for retracting a tool held slidably in the axial direction by a shaft hole, and a plurality of disc springs fitted in the draw bar in the shaft hole and biasing the draw bar in the drawing direction. , is fitted to the drawbar so as to be movable in the axial direction, both end surfaces abut individually on the two adjacent disc springs, inner and outer circumferential surfaces abut on the outer circumferential surface of the drawbar and the shaft hole, and the diameter A main shaft device for a cutting device, comprising a vibration absorbing and transmitting member having elasticity in one direction.