JPH07227705A - Tool holding device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a spindle device with good rotation balance that can stably cope with high speeds by adopting a structure that does not use a disc spring. [Structure] A spindle shaft 1 rotatably supported in a housing 12 having a taper hole 2 for mounting a tool holder at the shaft end, and a spindle holder 1 axially slidably fitted to an inner diameter surface of the spindle shaft 1 and a tool holder at one end. The drawbar 7 having the flange portion 55 at the other end of the holding portion 6 of 3 and the peripheral groove 52 and the through hole 53 communicating with the peripheral groove 52 at the inner diameter portion have one end surface abutted on the flange portion 55 at the shaft end of the drawbar 7. A fixed sleeve 51 fitted in close contact with the outer peripheral surface of the end of the spindle shaft 1, and a drawbar 7 through the fixed sleeve 51.
And a pressing means 60 for pressing the flange portion 55 to move the draw bar 7 in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool holding device for a machine tool, and more particularly to improving vibration balance.

[0002]

2. Description of the Related Art As a spindle device for a machine tool such as a machining center (MC), one shown in FIG. 5 is well known. This one has a taper hole 2 for attaching a tool at the tip of a spindle shaft 1.
The taper shank portion 4 of the tool holder 3 is fitted to the above to mount a predetermined tool. A draw bar 7 having a tool holder holding part 6 for fixing the tool holder 3 to the spindle shaft 1 by pulling the pull stud 5 of the tool holder 3 at the tip is inserted through the axial center of the spindle shaft 1. 500 to 20 backwards when the tool holder is attached
In order to pull with a large load of 00 kgf, a large number of disc springs 8
Is used.

In order to remove the mounted tool holder 3, a hydraulic cylinder (not shown) or the like is used to apply an axial load to the rear end of the draw bar 7 to compress the disc spring 8.

[0004]

However, in recent years,
The spindle device tends to be rapidly increased in speed, and the elastic force of a large number of disc springs 8 is used when the tool is attached to the draw bar 7.
In the conventional tool holding device for the spindle that draws in, there is a problem that the vibration of the device increases under the influence of the disc spring when rotating at high speed.

Moreover, the disc spring 8 is inserted into the draw bar 7 and housed and mounted in the shaft hole 1A provided in the spindle shaft 1. In order to allow the disc spring to bend, the disc spring 8 and the inner surface of the shaft hole are Since a certain amount of clearance is required between the drawbar outer diameter surface and the drawbar outer diameter surface, there is a limit in correcting the balance to suppress vibration. Further, even if the balance is corrected for high-speed rotation, there is a problem that the posture of the disc spring is changed during rotation or when the tool is repeatedly attached and detached to change the balance amount, resulting in large vibration.

Therefore, the present invention has been made in view of such conventional problems, and by providing a spindle device which does not use a disc spring, it is possible to stably cope with high speed. Is intended.

[0007]

A tool holding device according to the present invention comprises a spindle shaft having a tool holder mounting taper hole at its shaft end and rotatably supported by a housing through a bearing, and a tool holder at one end. And a draw holder for engaging the pull stud, and a draw bar driving end at the other end, and a draw holder for fixing the tool holder axially slidably fitted to the inner diameter surface of the spindle shaft, and the inner diameter portion. A peripheral groove and a through hole that communicates with the peripheral groove, and is fitted to the outer peripheral surface of the end of the spindle shaft, and the outer end of the drawbar is brought into contact with the drawbar drive end of the shaft end of the drawbar. A sleeve and a pressing means for pressing the drawbar driving end of the drawbar via the fixed sleeve to move the drawbar in the axial direction are provided.

[0008]

In the tool holding device of the present invention, the pressing means other than the disc spring is used as the source of the driving force for pulling in the draw bar. The draw bar abuts on the inner diameter surface of the spindle shaft without the intermediary of a disc spring, and the axial movement is directly guided by the spindle shaft. The operation during tool clamping is performed as follows.

By applying pressure to the flange portion provided on the end portion of the draw bar by the pressing means via the fixing sleeve,
Move the draw bar with a heavy load in the pull stud pull-in direction (backward direction). At that time, at the same time, the pressurized fluid is supplied from the through hole of the fixed sleeve to the circumferential groove of the inner diameter portion to release the interference between the fixed sleeve and the spindle shaft, thereby enabling the fixed sleeve to move in the axial direction. When the draw bar pulls in the pull stud and the tool holder is clamped, first, the pressurized fluid in the fixing sleeve is released to give a tightening allowance and fix the draw bar in the retracted state. Then, the pressure of the pressing means is released. This ensures that the tool holder is completely clamped.

The operation during tool unclamping is performed as follows. First, pressurized fluid is supplied to the inner circumferential groove of the fixed sleeve to release the interference with the spindle shaft. Next, in the opened state of the fixed sleeve, a forward pressing force is applied to the end of the draw bar. This causes the draw bar to move forward and the tool holder to be unclamped. Then, the pressurized fluid supplied to the fixed sleeve is drained.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The same or corresponding parts as in the conventional case are designated by the same reference numerals. FIG. 1 is a vertical sectional view of an embodiment of the present invention, showing a motor built-in type spindle device.

First, the structure will be described. The spindle shaft 1 has a plurality of (four in the figure) ball bearings 10 and one roller bearing 1.
It is rotatably supported in the housing 12 via the connector 1. The housing 12 is a cylindrical body that surrounds the outer circumferences of the bearings 10 and 11, and has an outer cylinder 1 having a mounting flange 13.
4, a front lid 15 attached to the front end surface of the outer cylinder 14 with a bolt B1 and a rear lid 16 attached to the rear end surface.

The ball bearing 10 is inserted together with the spacer from the front end side of the housing 12, and its outer ring 10a is fixed to the inner surface of the housing 12 by the front lid 15 via the outer spacer 17. On the other hand, the inner ring 10b is fixed to the outer peripheral surface of the spindle shaft 1 by the pressing ring 19 via the inner spacer 18. The roller bearing 11 is inserted together with the spacer from the rear end side of the housing 12, and its outer ring 11a has an outer ring pressing plate 26.
It is fixed to the inner surface of the housing 12 via. On the other hand, the inner ring 11 b of the roller bearing 11 is fixed to the outer peripheral surface of the spindle shaft 1 by a pressing ring 28 via a spacer 27.

Reference numeral 20 denotes an oil supply nozzle embedded in the bearing housing 12, and the tip of the oil supply nozzle 20 penetrates the outer spacer 17 so as to supply oil to the ball bearing 10. The oil supply passage 21 extends in the housing 12 in the axial direction, and is connected to an oil supply device (not shown) via an oil supply pipe joint 22 and an oil supply pipe 23 screwed to the housing rear lid 16. From the oil supply nozzle 20 to the ball bearing 10 and the roller bearing 1
The lubricating oil supplied to No. 1 lubricates each bearing and then flows back to the oil supply device through the discharge oil passage 24.

In this way, the housing 12 is rotatable.
A spindle hole 1 for tool attachment is formed at the center of the spindle end of the spindle shaft 1 which is supported by the spindle shaft 1, and a through hole 30 which extends from the depth of the taper hole 2 to the rear end of the spindle shaft 1 is formed in the spindle shaft 1. The drawbar 7 is formed through the axial center portion, and the drawbar 7 is slidably fitted and inserted into the inner diameter surface of the through hole 30.

Further, a rotor 31 of the built-in motor M is fixed to the outer diameter surface of the spindle shaft 1 via a rotor sleeve 32 by an interference fit. This rotor sleeve 3
2 has a shallow groove 33 formed on the inner peripheral surface thereof.
It can be removed by sending hydraulic pressure from the outside through the injection path 34 and releasing the interference fit with the spindle shaft 1. The stator 35, which is arranged coaxially with the rotor 31 so as to face the circumferential surface, is fixed to the inner circumferential surface of the housing 12 via a stator sleeve 36. The outer peripheral surface of the stator sleeve 36 is the outer cylinder 14 of the housing.
It faces a cooling jacket 37 composed of an annular space formed on the inner diameter surface of, and is forcibly cooled by a cooling fluid. 38 is an O-ring seal for preventing the leakage of the cooling fluid.

On the outer peripheral surface of the spindle shaft 1, a front balance ring 40 is attached to the front position of the rotor 31, and a rear balance ring 41 is attached to the rear position of the rotor 31. Further, at a position near the rear end of the spindle shaft 1, for example, a detection ring 46 of a magnetic rotary encoder 45 is fitted as a rotational position sensor,
It is fixed by a tightening nut 48 screwed into a male screw 47 formed on the rear end side of the spindle shaft 1. The outer circumference of the detection ring 46 of the rotary encoder 45 is formed with teeth at regular intervals, and the magnetic reading head 49 facing the teeth is mounted and supported on the side wall of the housing 12. By controlling the rotation of the servo motor M including the rotor 31 and the stator 35 based on the position detection signal of the rotary encoder 45, the rotation speed and rotation direction of the spindle shaft 1 can be set to low speed, high speed, and forward / reverse. Controlled.

The rear end of the spindle shaft 1 projects outside the rear cover 16 of the housing. The fixed sleeve 51 is fitted on the projected outer peripheral surface of the shaft end. A peripheral groove 52 is formed in the inner diameter of the fixed sleeve 51.
The circumferential groove 52 communicates with a hydraulic pipe mounting port 54 on the outer surface of the sleeve through a through hole 53. The rear end surface 51a of the fixed sleeve 51 is attached so as to slightly project further rearward from the rear end surface of the spindle shaft 1. The rear end surface 51a of the fixed sleeve is in contact with a flange portion (drawer nut) 55 screwed to the rear end of the drawbar 7.

Further, a spring return type hydraulic mechanism 60 is provided on the rear lid 16 of the housing as a pressing means for the fixed sleeve 51. The pressing means 60 has an annular groove functioning as a hydraulic cylinder 61 formed around the end surface of the rear lid 16 of the housing so as to surround the spindle shaft 1, and a cylindrical hydraulic piston 62 is formed in the hydraulic cylinder 61. Inserted together with the ring seal 63,
The hydraulic chamber 64 communicates with a hydraulic pipe port 66 on the outer surface via a hydraulic passage 65 that penetrates the rear lid 16 of the housing in the radial direction. The end surface of the hydraulic piston 62 contacts the front end surface 51b of the fixed sleeve 51 and presses the front end surface 51b to move the draw bar 7 backward in the axial direction. A spring mounting cover 67 is bolted to the end surface of the rear lid 16 of the housing, and a return spring 68 is provided between the spring mounting cover 67 and the end surface of the hydraulic piston 62.
Is installed.

Further, although not shown, the drawbar 7
The rear end is pressed by a hydraulic cylinder (not shown) to be driven forward in the axial direction. The tapered shank portion 4 of the tool holder 3 is fitted into the tapered hole 2 at the tip of the spindle shaft 1, and a small diameter neck portion 5a and a large diameter head portion 5b are provided at the top of the tapered shank portion 4. Is provided with a pull stud 5 having a through hole 30 for the spindle axis.
It is designed to fit inside.

On the other hand, the tool holding portion 6 at the tip of the draw bar 7
Is a sleeve 6b in which a plurality of balls 6a for gripping the pull stud 5 of the tool holder fitted in the through hole 30 are arranged at equal intervals around the circumference and held so as to be retractable in the radial direction.
When the drawbar 7 is pulled rearward with the pull stud 5 fitted in the sleeve 6b, the ball 6a
Protruding toward the inner diameter side of the sleeve, the head 5b of the pull stud 5
Is designed to be gripped.

Next, the operation of this embodiment will be described. When the tool holder 3 is attached to the shaft end of the spindle shaft 1 by a "tool clamp", the draw bar 7 is advanced by driving a hydraulic cylinder (not shown). In that state, for example, the taper shank portion 4 of the tool holder 3 carried by an automatic tool changer (ATC) is inserted into the taper hole 2 of the spindle shaft 1.
At this time, the ball 6a can be retracted in the outer diameter direction in the tool holding portion 6 at the tip of the draw bar 7, so that the head portion 5b of the pull stud 5 at the top of the taper shank portion is easily fitted into the sleeve 6b. .

Next, as shown in FIG. 2, a hydraulic pressure supply device (not shown) is passed through the pipe connected to the pipe mounting port 54 of the fixed sleeve 51 at the rear end of the draw bar 7 and the through hole 53 to the circumferential groove 52 of the inner diameter portion. Supply the hydraulic pressure P ₁ . Due to the hydraulic pressure P ₁ , a force in the radial direction acts on the inner diameter surface of the fixed sleeve 51 to expand the inner diameter, and the fixed sleeve 51
The tightening margin for the spindle shaft 1 is released, and the fixed sleeve 51 and the spindle shaft 1 can move relative to each other in the axial direction.

In this state, next, the hydraulic pressure P ₂ is supplied from the hydraulic pipe (not shown) connected to the pipe port 66 to the hydraulic chamber 64 of the hydraulic cylinder 61 of the pressing means 60 via the hydraulic passage 65.
As a result, the hydraulic piston 62 advances against the elasticity of the return spring 68, and a pressing force is applied to the flange portion 55 at the end of the drawbar via the fixed sleeve 51. The load causes the draw bar 7 to slide back along the inner diameter surface of the through hole 30 of the spindle shaft 1. At the same time, the tool holder 6 at the tip of the draw bar moves from the large diameter space 30a of the through hole 30 to the smaller diameter space 30b. As a result, the sleeve 6
The ball 6a of b is pushed by the inner peripheral surface of the space 30b and protrudes inside the sleeve 6b, and the base of the head 5b of the pull stud 5 of the tool holder 3 is tightened to hold the tool holder 3. Since the draw bar 7 is biased rearward by hydraulic pressure, it is pulled by this and the inclined surface of the taper shank portion 4 of the tool holder 3 is brought into close contact with the inner surface of the taper hole 2.

In this way, when the drawbar 7 pulls in the pull stud 5 and the tool holder 3 is clamped, the hydraulic pressure P ₁ of the fixed sleeve 51 is drained to reduce the inner diameter to give a tightening margin and fix the drawbar 7 in the retracted state. To do. Then
The pressure P ₂ in the hydraulic chamber 64 of the pressing means 60 is released. The elastic force of the return spring 68 causes the hydraulic piston 62 to move to the hydraulic cylinder 6.
It is pushed back in 1 (see FIG. 3).

The operation during "tool unclamping" is performed as follows. First, similarly to the above, the inner peripheral groove 5 of the fixed sleeve 51 is
The hydraulic pressure P ₁ is supplied to 2 to release the tightening margin of the spindle shaft 1. Next, with the tightening margin of the fixed sleeve 51 left open, a forward direction pressing force P ₃ is applied to the rear end of the draw bar 7 by a hydraulic cylinder (not shown). As a result, the drawbar 7 is fixed to the fixed sleeve 5 via the flange portion 55.
Move forward while pushing 1 (see Fig. 4).

The tool holder 6 at the tip of the draw bar 7 is also in front
The ball 6a pulls the tool holder 3
When the grip of the head 5 is released, the spindle shaft 1
Taper hole 2 at the tip and taper shank 4 of tool holder 3
And the tool holder 3 becomes unclamped.
It After that, the hydraulic pressure supplied to the fixed sleeve 51
P ₁, P₃And remove the fixed sleeve 51 to its original diameter.
You can do it.

Thus, according to this embodiment, the tool holder 3 can be automatically attached to the shaft end of the spindle shaft 1, and since the disc spring is not used, the drawbar 7 and the inner diameter surface of the spindle shaft 1 are fitted to each other with a small fit. It is possible to suppress the rotation balance, and it is possible to easily and highly accurately correct the rotational balance of the spindle shaft 1 by adjusting the balance rings 40 and 41.

Further, even if the spindle shaft 1 is rotated at a high speed and the tool holder 3 is repeatedly attached and detached, the balance of the rotation is not disturbed, so that the change of the vibration is suppressed. Can be achieved. It should be noted that the above-described embodiment shows an example of a basic configuration, and is not limited to the illustrated one. For example, the present invention is not limited to the motor built-in type spindle device, but is applicable to a type in which the spindle shaft 1 is driven by a drive source outside the housing.

Further, the pressing means for pulling the draw bar instead of the conventional disc spring is not limited to the illustrated hydraulic piston and return spring, or various modifications may be considered regarding the shape of the fixed sleeve and the flange portion (draw bar nut). To be

[0031]

As described above, the tool holding device of the present invention has the spindle shaft rotatably supported by the housing through the bearing and having the tapered hole for attaching the tool holder at the shaft end. A tool holder fixing drawbar having a tool holder holding portion that engages with a pull stud of the tool holder and a drawbar drive end at the other end, and fitted axially slidably on the inner diameter surface of the spindle shaft. A peripheral groove and a through hole communicating with the peripheral groove are formed in the inner diameter portion and are fitted to the outer peripheral surface of the end portion of the spindle shaft, and the outer end portion is brought into contact with the drawbar driving end portion of the shaft end of the drawbar. And a pressing means for pressing the drawbar drive end of the drawbar through the fixing sleeve to move the drawbar in the axial direction, so that the drawbar is retracted to clamp the tool. Spring is not necessary, resulting balance correction even becomes small unbalance even after repeated desorption of the tool with performed with high accuracy, the effect is obtained that can be stably corresponding to speed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining the operation at the time of tool clamping, which is shown in FIG.

FIG. 3 is a sectional view of relevant parts for explaining the operation during tool clamping.

FIG. 4 is a cross-sectional view of essential parts for explaining the operation during tool unclamping.

FIG. 5 is a vertical sectional view of a conventional spindle device.

[Explanation of symbols] 1 spindle shaft 2 taper hole 3 tool holder 4 taper shank portion 5 pull stud 6 tool holding portion 7 draw bar 10 bearing 11 bearing 12 housing 51 fixed sleeve 52 circumferential groove 53 through hole 55 flange portion 60 pressing means

Claims (1)

[Claims] 1. A spindle shaft rotatably supported by a housing through a bearing and having a tapered hole for attaching a tool holder at the shaft end, and a tool holder holding portion engaging at one end with a pull stud of the tool holder. A tool holder fixing draw bar which has a draw bar driving end at the other end and is axially slidably fitted to the inner diameter surface of the spindle shaft; and a circumferential groove in the inner diameter portion and a through hole communicating with the circumferential groove. A fixing sleeve fitted to the outer peripheral surface of the end of the spindle shaft and having an outer end abutting against the drawbar driving end of the drawbar shaft end; and the drawbar driving end of the drawbar being fixed to the fixing sleeve. A tool holding device comprising: pressing means for pressing the sleeve through a sleeve to move the draw bar in the axial direction.