JPH0230188Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a spindle restraint structure for a machine tool that restrains and fixes a quill that is screw-fed by a motor and is slidably supported on a spindle when necessary. The present invention relates to a spindle restraining structure for a machine tool suitable for reliably restraining a quill using inexpensive means.

[Prior Art] Conventionally, this type of spindle restraint structure is as follows:
For example, there is a type shown in FIG. 5 that is used in a spindle of a machining center.

A spindle 10 of the horizontal machining center is supported by a housing 40 via a bearing 11. The quill 12 is supported by the spindle 10 so as to be slidable in its axial direction, and rotates in conjunction with the spindle 10. An insertion portion 14 into which a tapered seal shank (not shown) is inserted is formed at the main shaft end 13, and the other end is pivotally supported by a bracket 20 via a bearing 15, and the quill 12
and bracket 20 are configured to be able to move together in the axial direction.

The ball screw bushing 30 attached to the bracket 20 is connected to the housing 4 through a bearing 41.
Screw into the ball screw 31 attached to 0,
The ball screw 31 is directly connected to a feed motor (servo motor with brake) 42a. That is, the movement of the bracket 20 and the quill 12 in the axial direction is induced by the drive of the feed motor 42a. Further, as shown in FIG. 6, an engaging portion 21 is formed on the upper side of the bracket 20 in the figure, and the engaging portion 21 is slidably engaged with a dovetail groove 51 of a guide portion 50 attached to the housing 40. It matches. That is, the axial movement of the bracket 20 is performed smoothly due to the presence of the guide portion 50.

A push rod 17 having a locking portion 16 (FIG. 5) at one end releases a tool shank (not shown) from the quill 12 under the action of a coil spring 18 and a piston 19.

With this configuration, the feed motor 42a (servo motor with brake) is driven, and this rotational movement is transmitted to the ball screw 31 and the ball screw bush 3.
0, the bracket 20 guided by the guide portion 50 and the quill 12 supported thereby are sent by a predetermined length. In order to fix the quill 12, the brake of the servo motor 42a is applied to restrain the movement of the quill 12 and perform clamping.

[Problems to be solved by the invention] As described above, in the conventional quill restraint structure, the servo motor 42a for feeding the quill 12 needs to be equipped with a brake, and the servo motor 42a with a brake is expensive. At the same time, there is a problem that the required capacity cannot be easily obtained. Furthermore, when the braking force is not sufficiently applied, the positioning of the quill 12 is ensured,
A problem arises in that the machining accuracy of the workpiece decreases.

This invention solves the above problems, and does not require expensive equipment such as a servo motor with a brake to feed the quill, and provides reliable and strong clamping force, improving machining accuracy. The purpose of this invention is to provide a spindle restraint structure for a machine tool that can be used in a machine tool.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention has a bracket that is slidably supported by a spindle and is pivotally supported by a bracket that is screw-fed by a motor and whose movement in the axial direction is restrained. In a spindle restraint structure for a machine tool that restrains and fixes a quill to be used as needed, at least two guide rods held on the fixed side of the machine are provided at positions corresponding to the screw shaft connected to the motor, and the guide rods are A clamp bushing that is slidably supported by the guide bushing is fitted and disposed on the bracket, and a hollow part that expands along the circumferential direction is provided in the thick walled part of the guide bushing to form a thin walled part. , constitutes a spindle restraining structure for a machine tool, which is provided with a gap portion into which pressure oil is introduced on the outer peripheral side of the clamp bush.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

Components having the same reference numerals as those in FIGS. 5 and 6 showing the prior art indicate the same components or components having the same function, and detailed description thereof will be omitted.

In this embodiment, a servo motor 42b without a brake is used as the feed motor directly connected to the ball screw 31, unlike the servo motor 42a with a brake in the conventional example.

The two guide rods 60 are arranged parallel to the sliding direction of the quill 12 and the ball screw 31, and both ends of each are fixed to the housing 40 on the fixed side of the machine. Further, the guide rod 60 is arranged at a position symmetrical to the ball screw 31, as shown in FIG. As shown in FIG. 2, the clamp bushes 61 are fitted into the bracket 20 and are arranged in slidable engagement with the guide rods 60, respectively. As shown in FIG. 3, the thick part of the clamp bushing 61 has an annular hollow part 62a concentric with the inner diameter of the clamp bushing 61.
is provided, thereby forming a thin wall portion 63. Further, an annular gap 64 is formed on the outer peripheral side of the clamp bush 61 so as to cover the thin wall portion 63.

As shown in FIG. 1, the pressure oil supply means 70 is attached to the housing 40 side, and is connected to the connection hole 65 by an oil supply pipe 71 so that pressure oil can be supplied to the cavity 64 shown in FIG. . The oil supply pipe 71 is formed of a flexible structure so as not to hinder the feeding movement of the bracket 20. The O-ring 66 is for smooth sliding between the guide rod 60 and the clamp bush 61, and seal members 67 are provided on both sides of the gap 64 to prevent pressure oil from leaking. It is being

With the above structure, in order to feed the quill 12 by a certain length and restrain it at a predetermined position, the servo motor 42b is driven and the bracket 20 on which the quill 12 is pivotally supported by the ball screw 31 and the ball screw bush 30 is moved. Send only a certain length. On this occasion,
The bracket 20 is stably supported by two guide rods 60 which are arranged in parallel at appropriate intervals at the target position of the ball screw 31, and act to move the bracket 20 smoothly. When the bracket 20 is fed, the quill 12 supported by the bracket is also smoothly fed by the same length. Next, in order to restrain the quill 12 and bracket 20 at a predetermined position, pressure oil is supplied to the cavity 64 by the pressure oil supply means 70. The thin wall portion 63 of the clamp bushing 61 is the annular cavity portion 6.
2a is formed to have lower rigidity than other parts, so it is deformed by the hydraulic pressure of the pressure oil introduced into the cavity 64 and comes into pressure contact with the guide rod 60. At this time, due to the existence of the annular cavity 62a, the thin wall portion 63 is elastically deformed without difficulty, and sufficient clamping force is applied to the guide rod 60.
Transform to give. Since the annular cavity 62a generates an air action, extreme stress concentration does not occur between the other thick wall portions and the thin wall portion 63 of the clamp bushing 61, and the stress generated during deformation is kept within the elastic limit. remains, and no plastic deformation occurs.

To release the clamp of the quill 12, it is sufficient to stop the supply of pressure oil in the cavity 64 and remove the pressure oil, and the thin part 63 of the clamp bushing 61 returns to its original state due to the elastic reaction force. It turns out. Therefore, the clamp bush 61 can smoothly slide along the guide rod 60.

As described above, in this embodiment, the guide mechanism and the spindle restraint mechanism are integrated, and in this point, it is significantly different from the conventional technology in which a servo motor with a brake was used to feed and restrain the spindle.
Therefore, in this embodiment, an inexpensive general servo motor can be used for the feed mechanism without requiring an expensive servo motor with a brake. Further, the spindle restraint mechanism integrated with the guide mechanism has a simple structure, can be manufactured at low cost, and can be expected to provide firm restraint.

Next, another embodiment of the present invention will be described with reference to FIG.

This embodiment is completely the same as the previous embodiment except for the shape of the thin wall portion 63 of the clamp bush 61. The thin wall portion 63 is formed by two annular cavities 62b separated from each other. Therefore, although the structure is a little more complicated than the previous embodiment, local deformation can be expected, and this deformation is efficiently accumulated, so that the clamp bush 61
The displacement of the inner diameter wall 68 is increased.

The advantage therefore arises that a lower axial pressure is required.

In the above embodiment, the annular cavities 62a, 6
Although the cross-sectional shape of the cross section 2b is rectangular, it may have a curved profile, for example, which can further alleviate stress concentration. Furthermore, although the annular cavities 62a and 62b are annular in the embodiment described above, they may be formed intermittently along the circumferential direction.

[Effects of the invention] According to the invention, the following effects can be achieved.

1. It is not necessary to use an expensive and difficult-to-obtain servo motor with a brake for the spindle restraint structure, and it can be implemented at low cost and easily.

2. Due to the presence of the cavity, the thin wall part can be reliably displaced by the amount required for clamping, there is little stress concentration, and deformation only occurs within the elastic limit, allowing for reliable clamping and functioning as a guide bushing. can be held.

3. Since the structure is simple, it is easy to implement, has fewer failures, has a longer lifespan, and has the advantages of excellent maintainability.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway vertical sectional view showing a spindle restraint structure according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 shows the main parts of the present invention. 4 is an enlarged sectional view showing essential parts of another embodiment of the present invention, FIG. 5 is a partially cutaway vertical sectional view showing a spindle restraint structure according to the prior art, and FIG. 5 is a sectional view taken along the - line in FIG. 5. FIG. 10...spindle, 12...quill, 17...
...Putdown, 20...Bracket, 30...
...Ball screw bushing, 31...Ball screw, 4
2a... Servo motor with brake, 42b...
Servo motor, 60... Guide rod, 61... Clamp bush, 62a, 62b... Annular cavity, 6
3... Thin wall portion, 64... Cavity portion, 70... Pressure oil supply means, 71... Supply pipe.

Claims (1)

[Scope of utility model registration request] In a spindle restraint structure for a machine tool, a quill is slidably supported by a spindle and pivotally supported by a bracket screw-fed by a motor. At least two guide rods held on the fixed side of the machine are provided at positions corresponding to the screw shafts to be connected, and a clamp bushing slidably supported by the guide rods is fitted and disposed on the bracket. ,
A hollow portion expanding along the circumferential direction is provided in the thick wall portion of the guide bushing to form a thin wall portion, and a void portion into which pressure oil is introduced is provided on the outer circumferential side of the clamp bushing. spindle restraint structure for machine tools.