JPH1199424A - Main spindle head supporting structure of machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a main spindle head supporting structure of machine tool which can improve processing precision by restraining swing of a main spindle head at the time of processing a work, and can attain size reduction and high- speed movement of main spindle head. SOLUTION: A direct-acting guide rail 20 is laid on the horizontal supporting part 17c of a second saddle 17, and a third saddle 22 is supported on the rail 20 so as to be capable of moving in Z-axis (front and rear) direction through a sliding member 21. A main spindle 24 is jointed to the front end surface of the saddle 22 and supported on a static pressure bearing 25 where the main spindle 24 is fitted to the vertical supporting part 17a of the second saddle 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle head support structure for a machine tool.

[0002]

2. Description of the Related Art A conventional horizontal machine tool is equipped with a moving column that moves in a left-right direction and a front-rear direction with respect to a bed.
In general, a spindle head is mounted on the movable column so as to be movable in a vertical direction, and a workpiece is machined by a machining tool attached to the spindle head. This horizontal machine tool
The weight of the moving column was heavy, and it was difficult to increase the moving speed in the left-right direction and the front-back direction. Further, it is necessary to increase the rigidity of the moving column in order to obtain the driving force of the processing, and the moving column becomes large, which is disadvantageous for moving at high speed.

[0003] Therefore, a fixed column is erected on the bed, a first saddle is mounted on the front surface of the column so as to be movable in the left-right direction, and a second saddle is moved vertically on the front surface of the first saddle. There has been proposed a horizontal machine tool which is mounted so as to be able to move the spindle head to the second saddle so as to be movable in the front-rear direction. In this machine tool, since the spindle head does not move in the front-rear direction together with the column, the column can be downsized and the spindle head can be moved in the front-rear direction at high speed.

In the above-mentioned horizontal machine tool, there are the following two types of structures for supporting a spindle head for gripping a processing tool. In the first type, a pair of linear guide rails and a slide mechanism are laid in the front-rear direction on the upper surface of the second saddle, and the spindle head is supported on the linear guide rails and the slide mechanism via a slide block. It is.

In the second type, a cylindrical hydrostatic bearing is installed on the upper surface of a second saddle in the front-rear direction, the main shaft is passed through the hydrostatic bearing, and a support cylinder is provided at the rear end of the hydrostatic bearing. By concatenating
A feed screw is rotated by a motor provided at the rear end of the support cylinder, and a nut fixed to the main shaft is operated by the feed screw to move the main shaft in the front-rear direction.

[0006]

However, in the first type, it is necessary to increase the amount of movement (machining stroke) of the tip of the spindle when the spindle approaches the workpiece.
The rigidity could not be increased. For this reason, there is a problem in that the processing tool is wobbled in a direction orthogonal to its axis, and the processing accuracy cannot be improved. In order to solve this problem, it is necessary to improve the rigidity of the spindle head itself and to make the linear motion guide rail and the slide mechanism rigid, and there is a problem that the spindle head support structure becomes large and cannot move at high speed.

The second type has a problem that the length of the hydrostatic bearing is required only for the stroke length of the spindle head in the front-rear direction, and the sliding resistance is large, the power loss is large, and it is difficult to move the spindle at high speed. Was. In addition, since the mechanism for driving the spindle head is located behind the spindle head, there is a problem that the dimension in the axial direction becomes large and the spindle head becomes large and heavy. In addition, it is necessary to provide a mechanism dedicated to the rotation stop of the main shaft, and it is difficult to obtain the accuracy of the rotation stop, and there is also a problem that the main shaft is twisted by the amount of the rattle of the rotation stop to reduce the processing accuracy.

The present invention has been made in view of the problems existing in the prior art as described above, and has as its object to suppress the runout and torsion of the spindle head at the time of processing a workpiece to thereby reduce the processing accuracy. It is an object of the present invention to provide a spindle head support structure for a machine tool, which can improve the speed of the spindle head and reduce the size of the spindle head.

[0009]

According to the first aspect of the present invention,
In order to achieve the above object, a fixed column is erected on a bed, a first saddle is mounted on a front surface of the column so as to be movable in the left-right direction, and a first saddle is moved on a front surface of the first saddle. A second saddle is movably mounted in a vertical direction perpendicular to the direction, a spindle head is movably mounted on the second saddle in a front-rear direction, and by a main shaft of the spindle head,
In a machine tool equipped with a tool for processing a workpiece, a third saddle constituting the spindle head is supported on the second saddle via a linear guide rail so as to be movable in the front-rear direction. A main shaft is connected to the front surface, and means for supporting the outer peripheral surface of the main shaft so as to be movable in the front-rear direction with respect to the second saddle by a hydrostatic bearing is adopted.

According to a second aspect of the present invention, in the first aspect, a fixed column is erected on the bed, a pair of upper and lower X-axis rails are laid on the bed and the column, and a first saddle is provided along the X-axis rail. Is mounted movably in the left-right direction, a pair of left and right Y-axis rails are laid on the front surface of the first saddle,
A second saddle is movably mounted in the vertical direction along the Y-axis rail, and a plurality of linear guide rails are laid on a horizontal support portion of the second saddle in parallel in the front-rear direction. A third saddle is movably mounted in the front-rear direction along the rail, and a main shaft is connected to the front surface of the third saddle in the front-rear direction. The outer peripheral surface of the main shaft is connected to a vertical support of the second saddle. It is supported by a hydrostatic bearing that is shorter than half the travel stroke of the spindle head.

According to the third aspect of the present invention, the first aspect is provided.
In 2 or 3, the third saddle and the main shaft are integrally formed. In the invention described in claim 4, claims 1 to 1
3. In any one of the first to third aspects, a mechanism for moving the third saddle in the front-rear direction may include a motor provided on a horizontal support portion of the second saddle, a feed screw rotated by the motor, and a feed screw. And a nut fixed to the third saddle.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 2 and 3, a column 12 is provided upright on the upper surface of the bed 11, and X-axis rails 13 and 13 are provided on the upper front surface (the left side in FIGS. 2 and 3) and the upper surface of the bed 11. Are laid in the X-axis (left-right) direction. Both X-axis rails 13, 1
A first saddle 14 having a vertically long rectangular frame shape is attached to 3 so as to be able to reciprocate in the X-axis direction by an X-axis moving device 15.
As shown in FIG. 2, the X-axis moving device 15 includes a motor (not shown) fixed to the bed 11, a feed screw 15a rotated at a predetermined position by the motor, and a feed screw 15a.
And a nut 15b fixed to the first saddle 14.

As shown in FIG. 3, Y-axis rails 16 are mounted on the front surfaces of the columnar portions 14a on both the left and right sides of the first saddle 14 in parallel with the Y-axis (vertical) direction. A second saddle 17 is mounted on the shaft rails 16, 16 such that the second saddle 17 can reciprocate in the Y-axis (vertical) direction by a Y-axis moving device 18. The second saddle 17 has a spindle head 19
Is installed. The Y-axis moving device 18 includes a motor 18
a, a feed screw 18b rotated at a predetermined position by the motor 18a, and a nut (not shown) fitted to the feed screw 18b and fixed to the second saddle 17.

The second saddle 17 is provided on the Y-axis rail 1.
A vertical support portion 17a guided and moved by 6, 6 and 16, a cylindrical shield tube 17b integrally formed on the upper rear surface of the support portion 17a and having a bottom opened and a lower end edge of the shield tube 17b. And a horizontal support portion 17c. The structure for supporting the spindle head 19 on the second saddle 17 will be described below.

As shown in FIGS. 1 and 5, the second saddle 1
A pair of right and left linear motion guide rails 20 are fixed to the upper surface of the horizontal support portion 17c of the seventh by bolts in parallel with the Z-axis (front-rear) direction. As shown in FIG. 1, the spindle head 1 is connected to the two guide rails 20 via a slide member 21.
The third saddle 22 forming the part 9 is supported. The third saddle 22 is reciprocated in the Z-axis direction by a Z-axis driving device 23 as shown in FIG.

A cylindrical main shaft 24 is connected and fixed to the front end surface of the third saddle 22, and the main shaft 24 is connected to the second saddle 1
Hydrostatic bearing 2 fitted and fixed to the upper part of vertical support portion 17a
5 support the reciprocating motion in the Z-axis direction. Although not shown, a gripping mechanism for gripping the processing tool and a motor for rotating the processing tool are housed inside the main shaft 24.

The Z-axis drive unit 23 includes a Z-axis drive motor 27 fixed to the rear end of the horizontal support 17c of the second saddle 17, a feed screw 28 rotated by the motor 27, The third screw is fitted to the screw 28 and the third
A nut 29 is fixed to the lower surface of the saddle 22.

Next, the operation of the machine tool configured as described above will be described. When processing a workpiece with the machine tool of this embodiment, a processing tool such as a drill (not shown) is attached to the tip of the main shaft 24 in FIG. on the other hand,
The workpiece is gripped by a workpiece gripping mechanism (not shown) mounted in front of the bed 11. When the workpiece is to be drilled at a desired position, the X-axis moving device 15 is operated to move the first saddle 14 in the X-axis direction.
The drill of the spindle head 19 is moved from the home position by a predetermined distance in the X-axis direction. Similarly, the Y-axis moving device 18
To move the second saddle 17 in the Y-axis direction to move the spindle head 19 from the home position by a predetermined distance in the Y-axis direction.

After the coordinates of the X axis and the Y axis of the main shaft 24 are determined in this manner, the drill gripped by the main shaft 24 is rotated, and the Z-axis moving device 23 is operated to operate the third saddle 22 and the main shaft 24. Is advanced in the Z-axis direction, and the drill gripped by the main shaft 24 is moved by a predetermined distance in the Z-axis direction. Then, the work is perforated by a drill.

Next, the operation grasped from the above embodiment,
The effects are listed together with the configuration. In the above embodiment, the horizontal support portion 17 of the second saddle 17
A linear motion guide rail 20 is laid on c, and the third saddle 22 is supported on the rail 20 so as to be movable in the Z-axis (front-back) direction. A main shaft 24 was connected to the front end surface of the saddle 22, and the main shaft 24 was supported by a hydrostatic bearing 25 fitted to the vertical support portion 17a of the second saddle 17. For this reason, the advantage of the linear motion guide system and the advantage of the hydrostatic bearing system can be exhibited, and the dimension of the main shaft 24 in the front-rear direction can be shortened. That is, in a state where the main shaft 24 is protruded by the maximum length L1 as shown in FIG. 1, the length L2 of the main shaft 24 supported by the hydrostatic bearing 25 is equal to or less than half the moving stroke of the main shaft 24. And And it becomes shorter by the length L3 of the third saddle 22 supported by the linear motion guide rail 20,
The sliding resistance is reduced.

Further, the Z-axis moving device 23 for driving the third saddle 22 can be disposed below the third saddle 22 so as to overlap with the saddle 22 in the Z-axis direction in the Z-axis direction. The length of the spindle head 19 and the Z-axis moving device 23 for driving the spindle head 19 in the Z-axis direction can be shortened accordingly.

In the above embodiment, since the second saddle 17 for supporting the spindle head 19 is L-shaped, the spindle head 19 is stably supported by the third saddle 22 and the hydrostatic bearing 25, and the workpiece is processed. In the operation, the support rigidity of the main shaft 24 is increased, the vibration of the main shaft 24 is suppressed, and the processing accuracy can be improved.

In the above-described embodiment, since the third saddle 22 also serves as a rotation stopping mechanism for the main shaft 24, there is no need to provide a mechanism dedicated to the rotation stopping mechanism, so that rattling of the main shaft 24 is prevented and machining accuracy is improved. Can be improved.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and may be embodied as follows, for example. As shown in FIG. 6, the third saddle 22 and the main shaft 24 are integrally formed of the same material. In this case, the assembling dimensional accuracy can be improved.

As shown in FIG. 7, the linear guide rail 2
0 and 20 are arranged so as to sandwich the central axis O of the third saddle 22, and the U-shaped slide member 21 is fitted to the rail 20. In this case, the vibration of the third saddle 22 in the direction orthogonal to the Z-axis direction can be reliably prevented and the third saddle 22 can be stably supported.

In the above embodiment, the first saddle 14 is
The second saddle 17 is supported movably in the Y-axis direction in the axial direction, but this is reversed. The technical ideas other than claims 1 to 4 grasped by the embodiment will be described below.

The third saddle 22 has linear motion guide rails 20, 20 located on both sides thereof with its center axis O interposed therebetween.
The spindle support structure for a machine tool according to any one of claims 1 to 4, wherein the U-shaped slide member (21) is movably supported in the Z-axis direction.

In this case, the third saddle 22 can be stably supported during the processing of the work. In this specification, the linear motion guide rails include, in addition to the guide rails 20 and 20 having a rectangular cross section in the above embodiment, guide rails having a circular cross section and dovetail grooves.
Also, three or more guide rails may be used.

In this specification, a hydrostatic bearing is a structure capable of applying a fluid pressure such as a hydraulic pressure or an air pressure to a cylinder formed in a cylindrical shape to apply a static pressure to the outer peripheral surface of the main shaft 24. Means things.

[0030]

As described above, claims 1, 2, 4
The described invention has an excellent effect that the machining accuracy can be improved by suppressing the run-out of the spindle head during machining, and the spindle head can be reduced in size and moved at high speed.

According to the third aspect of the present invention, in addition to the effects of the first aspect, the assembling accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is an essential part cross-sectional view showing one embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of a machine tool.

FIG. 3 is an exploded perspective view of the machine tool.

FIG. 4 is a sectional view of a main part showing a state where the spindle head is retracted.

FIG. 5 is a cross-sectional view showing a support structure of a spindle head with respect to a second saddle.

FIG. 6 is a front view of only essential parts showing another embodiment of the present invention.

FIG. 7 is a sectional view of only a main part showing another embodiment of the present invention.

[Explanation of symbols]

11 ... bed, 12 ... column, 13 ... X-axis rail, 14
... First saddle, 15 ... X-axis moving device, 16 ... Y-axis rail, 17 ... Second saddle, 17a ... Vertical support, 17c ...
Horizontal support, 18 ... Y-axis moving device, 19 ... Spindle head,
20: linear guide rail, 22: third saddle, 23: Z
Shaft moving device, 24: main shaft, 25: hydrostatic bearing.

Claims (4)

[Claims] 1. A fixed column is erected on a bed, a first saddle is mounted on a front surface of the column so as to be movable in the left-right direction, and a front surface of the first saddle is orthogonal to a moving direction of the first saddle. A machine tool having a second saddle movably mounted in the up-down direction, a spindle head mounted on the second saddle movably in the front-rear direction, and a tool for processing a workpiece mounted by the main spindle of the spindle head. In the above, a third saddle constituting the spindle head is supported on the second saddle via a linear guide rail so as to be movable in the front-rear direction, and a spindle is connected to a front surface of the third saddle; A spindle head support structure for a machine tool, wherein an outer peripheral surface of the main shaft is supported by a hydrostatic bearing with respect to the second saddle so as to be movable in the front-back direction. 2. A fixed column is erected on the bed, a pair of upper and lower X-axis rails are laid on the bed and the column, and a first saddle is mounted movably in the left-right direction along the X-axis rail. A pair of left and right Y-axis rails are laid on the front surface of the first saddle, and a second saddle is mounted movably in the vertical direction along the Y-axis rail, and a horizontal support portion of the second saddle includes: A plurality of linear guide rails are laid in parallel in the front-rear direction, and a third saddle is movably mounted in the front-rear direction along the linear guide rails. Then, the outer peripheral surface of the spindle is attached to the vertical support portion of the second saddle by の of the moving stroke of the spindle head.
2. The spindle head support structure for a machine tool according to claim 1, wherein the spindle head support structure is supported by a shorter hydrostatic bearing. 3. The spindle head support structure for a machine tool according to claim 1, wherein the third saddle and the spindle are integrally formed. 4. A mechanism for moving the third saddle forward and backward includes a motor provided on a horizontal support portion of the second saddle, a feed screw rotated by the motor, and a fitting to the feed screw. 4. A spindle head support structure for a machine tool according to claim 1, further comprising a nut fixed to said third saddle.