JP4870036B2 - Swivel table device - Google Patents

Description

  The present invention relates to a swivel table device used for an ultraprecision machine, and more particularly to a swivel table device on which a large thin work such as a mold used for manufacturing a light guide plate of a liquid crystal panel is placed.

  Some machine tools are provided with a turning table with an indexing function added to the table. As a conventional example of this type of turning table, for example, Patent Document 1 can be cited. As in Patent Document 1, in a conventional turning table, a rotating table is rotatably supported by ball bearings.

  In recent years, in machine tools, an ultra-precision machine that realizes ultra-precision machining has been developed as a result of advances in control technology. With this ultra-precision processing machine, it has become possible to process a mold for molding an optical lens or the like.

In such a turning table of an ultra-precision processing machine, the shaft of the table is supported by a fluid bearing, particularly an air bearing, instead of the ball bearing.
Japanese Patent Laid-Open No. 9-19848

Recently, the size of liquid crystal panels has been remarkably increased, and accordingly, molds used for manufacturing light guide plates and the like have also been increased in size.
In order to handle large workpieces on the swivel table of an ultra-precision machine, the major issues are handling the workpiece shape and weight, ensuring the accuracy of the swivel base surface after indexing, and achieving compatibility with the spindle function.

  First, in order to handle large workpieces, it is necessary to enlarge the swivel table of the swivel table. In the swivel table of the type in which the swivel table is supported by an air bearing, the size of the table is reduced due to the production of the air bearing. There are limitations. In addition, the weight of the swivel base is proportional to the square of the diameter. Therefore, as the swivel base is increased, the servo mechanism needs to be redesigned significantly. First, the entire machine configuration must be reviewed.

  Regarding the problem of ensuring the accuracy of the upper surface of the swivel base after the second indexing, there is a problem that the height of the upper surface of the swivel base is slightly shifted before and after the indexing. The reason is considered to be that there is no error because the rotating shaft of the swivel base and the upper surface of the air bearing are not precisely perpendicular to each other, and the surface accuracy of the upper surface of the air bearing is affected. When the workpiece becomes large, there are very few errors in perpendicularity, and the accuracy of the top surface is large, which greatly affects the accuracy of the top surface of the swivel, but this cannot be easily adjusted.

  Regarding the problem of compatibility with the third spindle function, fluid bearings such as air bearings and oil bearings are inherently used as high-accuracy bearings, but recently, bearings that support a spindle that rotates at high speed, That is, it has been used as a bearing for a main spindle for processing. Therefore, in the case of a swivel table supported by an air bearing, it has been studied to add a spindle function for rotating the swivel at a high speed together with an indexing function.

  However, if the workpiece is large, the bearing body inevitably increases in size, so that the area of the cylindrical portion increases, resulting in an increase in air resistance and high speed rotation. That is, there is a problem that the work size is not compatible with the spindle function.

  Therefore, the object of the present invention is to solve the problems of the prior art, ensure the handling of large workpieces with the turning table of the ultra-precision machine, and ensure the accuracy of the swivel base surface after indexing. An object of the present invention is to provide a swivel table device that solves problems such as compatibility with the spindle function at once.

  In order to achieve the above object, the present invention provides a swivel table in which a swivel on which a work is placed is rotatably supported by a bearing, and has chuck means for fixing the work, and is mounted coaxially on the swivel. A chuck base having a diameter larger than that of the swivel base, a motor unit that rotationally drives the swivel base, and that is disposed at the center of the swivel base coaxially with the rotation axis of the swivel base; And a hydrodynamic bearing that rotatably supports the swivel base and the rotating shaft, and an auxiliary table that is disposed outside the swivel base and supports an outer peripheral portion of the chuck base. It is what.

  In the present invention, the upper surface of the auxiliary table forms a reference surface of the upper surface accuracy of the chuck table, and the reference surface of the auxiliary table is a self-cut surface processed by the machine tool itself in which the turning table device is used. Have

In the present invention, it is preferable that the main body portion of the auxiliary table has a rib structure for weight reduction.
The chuck table fixing means comprises a vacuum chuck that sucks a workpiece by evacuation, and the auxiliary table includes a vacuum chuck means having both functions of chucking the chuck table and floating the chuck table. Have.

  In the present invention, the fluid bearing is an air bearing, and the servo motor having the indexing function and the spindle function is used for the motor part of the swivel base.

  According to the present invention, in the swivel table of an ultra-precision machining machine, the swivel itself can be handled by a large workpiece without increasing the size, and the upper surface accuracy of the swivel after the indexing is ensured. It can solve problems such as compatibility with functions all at once and contribute to the realization of high-precision machining.

Hereinafter, an embodiment of a turning table device according to the present invention will be described with reference to the accompanying drawings.
In FIG. 1, reference numeral 10 indicates the entire turning table device. W is a thin plate-like workpiece. The swivel table device 10 is installed on the swivel base 14 so as to be rotated by a table main body 11, an auxiliary table 12, a motor unit 13, and a vacuum for fixing the work W. And a chuck base 15.

  First, the table body 11 is installed on the bed 16. In this embodiment, a V-groove 17 is formed on the upper surface of the bed 16 as a linear guide. The table body 11 is guided to move along the V-groove 17.

  Next, the swivel base 14 will be described. Reference numeral 18 denotes a rotating shaft of the swivel base 14, and the rotating shaft 18 is a hollow shaft having a cylindrical structure. The swivel base 14 is rotatably supported by a pair of upper and lower air bearings 20 a and 20 b provided inside the housing 19. In this case, in the case of the lower air bearing 20a, a gap is set between the air bearing 20a and the upper surface of the flange portion 18a of the rotary shaft 18 and the outer peripheral surface of the lower half of the rotary shaft 18, and compression is performed in this gap. Air is supplied. In the upper air bearing 20b, a gap is set between the air bearing 20b, the outer peripheral surface of the upper half of the rotary shaft 18, and the lower surface of the swivel base 14, and compressed air is supplied to the gap.

  Next, as for the motor part 13, the following built-in type servo motors are arrange | positioned coaxially at the center part of the turntable 14. FIG. A stator holding member 21 is disposed inside the rotary shaft 18, and a stator 22 constituting the motor unit 13 is attached to the inner peripheral surface of the stator holding member 21. A rotor shaft 23 is fixed to the center of the lower surface of the swivel base 14, and a rotor 24 is attached to the outer peripheral portion of the rotor shaft 23. Such a servo motor is a servo motor capable of realizing both an index function that rotates by a certain angle and a spindle function that rotates continuously. Reference numeral 25 indicates an encoder.

  The vacuum chuck table 15 is attached to the upper surface of the swivel table 14. A vacuum evacuation hole is opened on the surface of the vacuum chuck table 15 so that the workpiece W can be adsorbed and fixed by the vacuum chuck function. Reference numeral 26 indicates a rotary joint for connecting an air pipe 27 for supplying air to the air bearings 20a and 20b.

  Next, the auxiliary table 12 disposed outside the swivel base 14 will be described. In this embodiment, the auxiliary table 12 has a structure surrounding the swivel base 14. The upper surface of the auxiliary table 12 serves as a reference surface 12 a, and this reference surface 12 a serves as a reference for the upper surface accuracy by replacing the upper surface of the swivel base 14.

  When the outer diameter of the auxiliary table 12 is R and the inner diameter is r, the outer diameter of the swivel base 14 is smaller than r, and the outer diameter of the vacuum chuck base 15 is set to be substantially equal to R. However, the outer diameter of the vacuum chuck table 15 does not necessarily need to match the outer diameter R of the auxiliary table 12.

  The processing for forming the reference surface 12a on the upper surface of the auxiliary table 12 is preferably performed by so-called self-cutting. That is, the reference surface 12a is processed by the machine tool itself that is installed and used instead of processing the reference surface by a machine different from that in which the turning table device 10 is used. The reference surface 12a can be used.

  In addition, the vacuum table 15 is similar to the vacuum chuck table 15 in that a large number of vacuuming holes are opened on the upper surface of the auxiliary table 12, and an air passage constituting a vacuum chuck is formed inside the auxiliary table 12. Yes. In the case of the auxiliary table 12, the auxiliary table 12 is connected to the pipe 29 through the joint 28, and not only vacuums and sucks but also blows air from the hole on the upper surface to slightly float the vacuum chuck table 15 and the swivel table 14. It has a function to make it.

  The auxiliary table 12 preferably has a light weight structure in which the ribs 30 are formed.

  The turning table device according to the present embodiment is configured as described above. Next, the operation and effect will be described.

First, the workpiece W is placed on the vacuum chuck table 15 and the workpiece W is fixed to the vacuum chuck 15 by evacuation.
Next, when the swivel base 14 is swung to determine the angular position of the workpiece W, the air is blown out from the reference surface 12a of the auxiliary table 12 as shown in FIG. Keep 15 floating. With the vacuum chuck plate 15 kept floating, the swivel base 14 is swung by the commanded angle. At this time, the angle is fed back by the encoder 25, and the rotation of the motor unit 13 is controlled so as to coincide with the commanded angular position.

When the angular position of the workpiece W is positioned, the ejection of air from the surface of the auxiliary table 12 is stopped, and the vacuum chuck plate 15 that has floated until then is seated on the reference surface 12 a of the auxiliary table 12.
Thereafter, as shown in FIG. 2B, the vacuum chuck plate 15 is sucked and fixed to the reference surface 12a of the auxiliary table 12 by evacuation.

  According to the turning table device of the present embodiment, the following effects can be obtained.

  First, in order to cope with the larger workpiece W, conventionally, the swivel base 14 itself has been required to be enlarged. However, in the swivel table device according to the present embodiment, the work W and the vacuum chuck are supported by the auxiliary table 12. Since the plate 15 is supported and fixed, it is possible to cope with an increase in the size of the workpiece without enlarging the swivel base 14 itself.

  FIG. 3 shows the turning table device 10 that can handle a larger workpiece W. In this turning table device 10, as compared with FIG. 1, only the auxiliary table 12 is large.

  As the swivel base 14 does not need to be made larger in this way, the motor unit 13 can be made a large capacity motor, the design of the servo mechanism can be changed, heat generation countermeasures, etc. can be used without reexamining the overall machine configuration. A large workpiece W can be handled only by installing the table 12.

  Secondly, according to the turning table device 10 according to the present embodiment, the top surface accuracy before and after indexing does not depend on the top surface accuracy of the swivel base 14 and the accuracy of the rotary shaft and the air bearing. The accuracy of the upper surface is determined by the accuracy of the parallelism of the reference surface 12a, which is the upper surface of the auxiliary table 12, and the front and back surfaces of the vacuum chuck plate 15.

  Then, the accuracy of the reference surface 12a of the auxiliary table 12 and the back and front surfaces of the vacuum chuck plate 15 can be remarkably improved by processing them on their own machine. On the other hand, when it depends on the accuracy of the swivel base 14, the rotary shaft 18, and the air bearings 20a and 20b, the rotary shaft 18 of the swivel base 14 and the upper surface of the air bearing 20b are not precisely perpendicular to each other. Compared to the fact that it is difficult to eliminate the error and the improvement of the top surface accuracy cannot be realized, in this embodiment, the accuracy of the auxiliary table 12 corresponding to the large size can be easily secured by self-cutting. Can be adjusted easily.

  Thirdly, it is possible to use a built-in type servo motor for the motor unit 13 to realize the indexing function by the position control of the servo motor and to also use the spindle function by continuous rotation.

  In other words, in the case of the conventional swivel table device used for ultra-precision machining, an air bearing is used as the bearing. However, if the bearing is enlarged in accordance with the enlargement of the workpiece, the air bearing cannot cope with high-speed rotation. Becomes apparent.

  On the other hand, according to the turning table device of the present embodiment, the auxiliary table 12 is used for a large workpiece W while using an air bearing that supports high-speed rotation. And it is possible to achieve both indexing.

Sectional drawing which shows one Embodiment of the turning table apparatus by this invention. Sectional drawing of the turning table apparatus corresponding to a large sized workpiece | work. Sectional drawing which shows operation | movement of the turning table apparatus by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Turning table apparatus 11 Table main body 12 Auxiliary table 12a Reference surface 13 Motor part 14 Turning stand 15 Vacuum chuck stand 16 Bed 17 V groove 18 Rotating shaft 19 Housing 20a, 20b Air bearing 21 Stator holding member (motor receiving)
22 Stator 23 Rotor shaft 24 Rotor 25 Encoder W Workpiece

Claims (8)

In a swivel table in which a swivel on which a work is placed is rotatably supported by a bearing,
Chuck means for fixing a workpiece, and a chuck base that is coaxially mounted on the swivel base and has a larger diameter than the swivel base;
A motor unit that rotationally drives the swivel base and is disposed at a central portion of the swivel base coaxially with a rotation axis of the swivel base;
A hydrodynamic bearing that is coaxially disposed outside the motor unit and rotatably supports the swivel base and the rotary shaft;
An auxiliary table disposed outside the swivel base and supporting an outer periphery of the chuck base;
A swivel table device comprising:   The turning table device according to claim 1, wherein the upper surface of the auxiliary table forms a reference surface of the upper surface accuracy of the chuck table.   The turning table device according to claim 1, wherein the reference surface of the auxiliary table has a self-cut surface processed by a machine tool itself in which the turning table device is used.   The swivel table device according to claim 1, wherein the main body portion of the auxiliary table has a rib structure for weight reduction.   The turning table device according to claim 1, wherein the chuck table fixing means includes a vacuum chuck that sucks a workpiece by evacuation.   2. The swivel table device according to claim 1, wherein the auxiliary table has a vacuum chuck means having both functions of adsorption of the chuck table and floating of the chuck table.   The swivel table device according to claim 1, wherein the fluid bearing is an air bearing.   The turning table device according to claim 1, wherein the motor unit of the swivel base is a servo motor that has both an indexing function and a spindle function.

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