JP2005238406A - Precision processing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain ultra-precision processing accuracy, by restraining rotational vibration, by imparting the rotational vibration restraining function to a bed itself. <P>SOLUTION: This precision processing machine has, on its bed 20, moving bodies 21 and 22 respectively moving in the orthogonal two directions on a plane. The precision processing machine is formed into a deformed bed for reducing a height difference between a support point A of the bed supported by a support mechanism 32 and the rotational center G of the rotational vibration of a machine body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a precision processing machine that processes precision molds, optical components, and the like, and more particularly to a technique for suppressing rotational vibration generated in a machine body.

  In devices that perform high-precision processing and processing, such as semiconductor manufacturing equipment and precision processing machines, the influence of vibrations has a large effect on accuracy, so the transmission of external vibrations can be cut off and vibrations generated in the machine body can be removed. A vibration isolator is necessary for this purpose.

  This type of vibration isolation device is a passive vibration isolation device that uses an elastic body such as a spring or rubber to dampen vibrations, and a combination of an air spring and an electromagnetic actuator. An active vibration isolator for removal is used.

  As an example of an active vibration isolator, in a semiconductor exposure apparatus, rotation that drives a rotary inertia element to suppress rotational vibrations such as pitching, rolling, and rolling caused by movement of an XY stage mounted on the machine body A combination of an actuator and a rotating mass unit that applies torque to the anti-vibration table by the driving reaction force of the rotating inertial element, and the rotational vibration by controlling the driving of the rotating mass unit while performing appropriate compensation calculation based on the detected rotating vibration There is an active vibration isolator that reduces noise (see Patent Document 1).

In addition, some precision processing machines that perform ultra-precision processing such as lens molds and lenses are equipped with a vibration isolation device that blocks the transmission of vibration between the base and the machine body in order to reduce the effects of external vibration. Proposed (see Patent Document 2)
JP 2001-304332 A JP-A-11-70428

  FIG. 5 is a diagram schematically showing a situation in which rotational vibration occurs in a conventional precision processing machine. Reference numeral 10 is a bed, and the bed 10 is supported by a vibration isolation device 12. A first table 14 that moves in the front-rear direction (X-axis) and a second table 15 that moves in the left-right direction (Z-axis) are installed on the bed 10. The first table 14 is provided with a grinding spindle 16, and the second table 15 is provided with a workpiece spindle 17.

  The fact that the X-axis movement of the first table 14 and the Z-axis movement of the second table 15 are continuously performed during processing means that the heavy object moves in the horizontal direction on the bed 10. When the center of gravity is G, in the case of a precision processing machine supported by the vibration isolation device 12, a difference between the support point A of the bed 10 and the center of gravity G of the bed 10 is a distance h in the height direction. For this reason, when the first table 14 and the second table 15 are moved on the bed 10, a moment centering on the center of gravity G acts on the bed 10, and this causes a rotational vibration. Such rotational vibration is rarely a problem for general machine tools, but in ultra-precision aspherical processing such as grinding a lens, even a slight twist of the machine body caused by rotational vibration This causes a reduction in machining accuracy.

  Further, in the case of a precision processing machine, the structure supported by the vibration isolation device 12 is changed to promote the generation of rotational vibration. On the other hand, a countermeasure using an active vibration isolator as applied to a semiconductor manufacturing apparatus can be considered, but a heavy precision processing machine is not realistic in terms of control responsiveness and complexity.

  Accordingly, an object of the present invention is to provide a precision processing machine that can maintain the ultra-precision processing accuracy by solving the problems of the prior art and providing the bed itself with a rotational vibration suppressing function. It is in.

  In order to achieve the above-described object, the present invention provides a precision processing machine having a moving body on a bed that moves in two directions orthogonal to each other on a plane. It is characterized by comprising a deformed bed that reduces the difference in height from the rotational center of rotational vibration.

  In the present invention, the bed can be constituted by a T-shaped deformed bed having a protruding portion protruding downward between the support mechanisms. Moreover, it is preferable that the said support mechanism consists of a vibration isolator.

In the present invention, the feed mechanism of the moving body that moves on the bed may be a linear motor drive feed mechanism instead of the ball screw mechanism.
Furthermore, in the present invention, the bed may be provided with a recess that makes the distance between the workpiece processing point and the rotational center of the rotational vibration as small as possible.

  According to the present invention, since the position of the center of gravity is lowered by making the bed of a T-shaped integral structure having a protruding portion between the support points A, the height between the support point and the center of gravity G serving as the rotation center of the rotational vibration is increased. The difference in height can be made as small as possible, and a structure in which a horizontal moment that causes rotational vibration is difficult to work.

Hereinafter, an embodiment of a precision machine according to the present invention will be described with reference to the accompanying drawings.
First embodiment
FIG. 1 is a view showing a side surface of a precision processing machine according to a first embodiment of the present invention. This precision processing machine is a processing machine for performing ultra-precise processing for grinding and turning lens parts and the like.

  In FIG. 1, reference numeral 20 indicates a bed which is a base of a precision processing machine. On the upper surface of the bed 20, there are provided high-precision and high-rigidity rolling guides in two orthogonal directions as horizontal guide surfaces, and the first table 21 and the second table 22 are installed so as to be movable along the rolling guides. Has been. A column 23 is mounted on the first table 21, and a vertical guide surface is provided on a side surface of the column 23. The grinding spindle 24 is composed of an aerostatic spindle, and is installed so as to be movable up and down along the vertical guide surface. The second table 22 is mounted with a work spindle 25 which is also composed of an aerostatic spindle. The work spindle 25 is driven by a motor 26.

  In the precision processing machine of this embodiment, a ball screw feed mechanism is used as the feed mechanism, and the axis for moving the first table 21 to feed the grinding spindle 24 back and forth feeds the X axis and the grinding spindle 24 up and down. The axis that moves the second table 22 in order to feed the Y axis and the work spindle 25 to the left and right is the Z axis. The rotation axis of the work spindle 25 is the C axis. Reference numeral 27 is an X-axis servomotor for driving the feed mechanism of the grinding spindle 24, and 29 is a Z-axis servomotor for the first table 21.

  Next, the bed 20 is configured as the following irregularly shaped bed in the first embodiment, unlike the rectangular parallelepiped bed generally used.

  The bed 20 is a T-shaped integrated bed composed of two parts, a bed main body 30 that is a rectangular parallelepiped and a projecting portion 31 that protrudes downward from the center of the lower surface of the bed main body 30. In the bed 20, the portions protruding from the left and right sides of the protruding portion 31 are support portions 31 a and 31 b, and the support portions 31 a and 31 b are supported by a vibration isolation device 32 as a support mechanism installed on the floor. ing. In the state where the bed 20 is supported by the vibration isolation device 32, the lower surface of the protruding portion 31 is separated from the floor surface. As the vibration isolator 32, for example, a passive vibration isolator using an air spring is used. In addition, the vibration isolator 32 can be an active vibration isolator using both an air spring and an electromagnetic actuator.

  The precision processing machine according to the present embodiment is configured as described above. Next, the operation and effect thereof will be described.

  While the workpiece is processed by the precision processing machine, the X-axis movement of the grinding spindle 24, the Z-axis movement of the workpiece spindle 25, and the Y-axis movement of the grinding spindle 24 are continuously performed. Such movement of heavy objects on the bed 20 causes a moment to act on the bed 20 and causes vibration.

FIG. 2 is a diagram schematically showing the precision processing machine according to the present embodiment. The center of gravity of the bed 20 is indicated by G, and the support point of the bed 20 supported by the vibration isolation device 32 is indicated by A.
When the first table 21 and the second table 22 are moved on the bed 20 to move the X axis of the grinding spindle 24 and the Z axis of the workpiece spindle 25, the bed 20 has a horizontal axis around the center of gravity G. The moment of acting. The magnitude of the moment varies depending on the positions of the grinding spindle 24 and the workpiece spindle 25.

  The moment around the horizontal axis causes rotational vibration with the center of gravity G as the center of vibration, and as the distance h between the center of gravity G of the bed 20 and the support point A increases, the moment around the horizontal axis increases (FIG. 5). reference). Although the moment about the horizontal axis acting on the bed 20 also causes the bed 20 to vibrate in the vertical direction, the vibration in the vertical direction is suppressed by the vibration isolation device 32. Moreover, in the case of the bed 20 having a T-shaped integral structure having the protruding portion 31 protruding downward from the center of the lower surface of the bed main body 30 between the support points A as in the present embodiment, the position of the center of gravity G is lowered. The difference in height between the support point A and the center of gravity G that is the center of rotation of the rotational vibration can be made as small as possible. Therefore, since the bed 20 has a unique structure in which a moment around the horizontal axis that causes rotational vibration is difficult to work, a rotational vibration suppressing function can be added to the bed 20 itself.

  In a precision processing machine such as this embodiment, which requires a processing accuracy of the order of 1 nm and a slight torsion of the machine body caused by rotational vibration affects the processing accuracy, the vibration isolator 32 suppresses the processing accuracy as described above. By adopting a structure that is difficult to generate difficult rotational vibration, there is a great effect in preventing a reduction in processing accuracy.

  Further, it is possible to reduce the difference in height between the support point A and the center of gravity G, which is the rotation center of rotational vibration, as much as possible by using a conventional suspension type vibration isolator. There is a drawback that the installation area increases. In this respect, in this embodiment, since the bed 20 is realized by the T-shaped deformed structure, space can be saved.

Second embodiment
Next, a precision machine according to a second embodiment of the present invention will be described with reference to FIG.

  In the precision processing machine according to the second embodiment of the present invention, the feed mechanism of the first table 21 and the second table 22 moving on the bed 20 is constituted by a feed mechanism of a linear motor mechanism. Since the structure of the bed 20 is the same as that of the first embodiment shown in FIG. 1, the same reference numerals are assigned to the same components, and the description thereof is omitted.

  In FIG. 3, reference numeral 40 indicates an X-axis linear motor mechanism that sends the first table 21. The X-axis linear motor mechanism 40 includes a coil array 41 extending in the X-axis direction at the center of the upper surface of the bed 10 and a permanent magnet 42 attached to the center of the bottom surface of the first table 21 so as to face the coil array 41. It is configured. The Y-axis linear motor mechanism that sends the second table 22 is configured in the same manner (not shown).

It is well known that when a linear motor is adopted as a feed mechanism of a precision processing machine, rotational vibration of the machine main body is a serious obstacle to achieving improved position control accuracy. Therefore, by using a bed having a structure that hardly generates rotational vibration as in the present embodiment, it is possible to easily improve the positioning accuracy of the table by driving the linear motor.
Third embodiment
Next, FIG. 4 shows a precision processing machine according to the third embodiment of the present invention.
As in the first embodiment, the third embodiment is provided with a protruding portion 31 protruding downward from the center of the lower surface of the bed body 30, and a support point A of the bed 20 and a center of gravity G serving as a rotation center of rotational vibration. In addition to making the difference in height as small as possible, a recess 46 is formed in the upper part of the bed main body 30, and the first table 21 on which the grinding spindle 24 is mounted and the workpiece spindle 25 are mounted on the bottom surface of the recess. The second table 22 is arranged.

  According to the third embodiment, the distance between the machining point B of the workpiece and the center of gravity G, which is the rotation center of the rotation vibration, can be made as small as possible. It is possible to minimize the influence of rotational vibration in

The side view which shows the precision processing machine by 1st Embodiment of this invention. The schematic diagram which shows the gravity center position of the precision processing machine. The side view which shows the precision processing machine by 2nd Embodiment of this invention. The schematic diagram which shows the precision processing machine by 3rd Embodiment of this invention. The schematic diagram which shows the positional relationship of the conventional precision processing machine, a vibration isolator, and a gravity center.

Explanation of symbols

20 Bed 21 First table (moving body)
22 Second table (moving body)
23 Column 24 Grinding spindle 25 Work spindle 30 Bed body 31 Protruding parts 31a, 31b Supporting part 32 Vibration isolator (supporting mechanism)
40 X-axis linear motor mechanism 46 Recess A Support point B Processing point G Center of gravity

Claims (5)

  In a precision processing machine having a moving body on a bed that moves in two directions orthogonal to each other on a plane, the difference in height between the support point of the bed supported by the support mechanism and the rotational center of the rotational vibration of the machine body is reduced. A precision processing machine characterized by comprising an irregularly shaped bed.   The precision processing machine according to claim 1, wherein the bed comprises a T-shaped deformed bed having a protruding portion protruding downward between the support mechanisms.   The precision processing machine according to claim 2, wherein the support mechanism includes a vibration isolation device.   The precision processing machine according to claim 1, wherein the feed mechanism of the moving body moving on the bed is a linear motor drive feed mechanism.   The precision processing machine according to claim 1, wherein the bed has a concave portion that makes the distance between the processing point of the workpiece and the rotational center of rotational vibration as small as possible.

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