JP5122416B2 - Air table device and bearing interval correction method - Google Patents

Description

  The present invention relates to a linear motor-driven air table device and a bearing spacing correction method used for moving a workpiece, a measuring instrument, a robot, etc. in a machine tool, a precision machine, a liquid crystal inspection device, a liquid crystal transfer device, and the like.

  An air table device that linearly moves a moving body such as a table by driving a linear motor along a static pressure air bearing linear guide is widely used in precision machine related equipment and liquid crystal related equipment. In this type of air table device, high-speed movement and high positioning accuracy can be realized by employing a static pressure air bearing and a linear motor.

  In the air table device, it has conventionally been a problem that the bearing gap of the hydrostatic air bearing changes due to various causes.

  For example, it is known that the bearing clearance of the hydrostatic air bearing of the guide rail changes due to the difference in thermal expansion between the base and the guide rail and the stage. Since the bearing gap is eliminated in the worst case when the stage is enlarged, Patent Document 1 discloses a structure in which the distance between the pair of horizontal air-air bearings is set small regardless of the size of the stage. .

  By the way, the air table apparatus conventionally utilized includes an air table apparatus in which the slider 20 travels along a T-shaped guide rail 22 as shown in FIG.

  As shown in FIG. 5, on both sides of the slider 20, the lateral air bearing 4 facing the vertical surface of the guide rail 22 and the upper air bearing 5 and the lower air bearing 6 facing the upper and lower surfaces of the guide rail 22 are attached. ing. Between the guide rail 22 and these air bearings, a bearing gap of several μm to several tens of μm is secured.

A linear motor is employed as the drive system, and a large number of magnet plates 25 are arranged in a line at the center of the upper surface of the rail, and the slider 20 is equipped with a coil 30.
JP 2006-084034 A

  In the air table device shown in FIG. 5, if the slider 20 is equipped with a linear motor, the center of the coil 30 and the center of the slider 20 are not aligned. This is due to the following structure.

  As shown in FIG. 6, the linear motor includes a coil 30 and a magnetic pole detector 32. The coil 30 is a coil that occupies a relatively large area with respect to the main body of the slider 20 in order to obtain a required acceleration. For this reason, when the coil 30 and the magnetic pole detector 32 are attached to the slider 20, an offset amount is generated at the center of the coil 30 with respect to the center of the slider 20.

  Thus, if the center of the slider 20 and the center of the coil do not coincide, the attractive force is not applied to the center of gravity of the slider but becomes an uneven load. Then, before and after the traveling direction, the bearing gap is non-uniform in the slider. This non-uniformity of the bearing gap is exemplified in FIG.

  Even if the non-uniformity of the bearing gap is a difference of several μm, since the slider 20 is inclined, air flows out from the larger gap and the rigidity of the bearing is reduced. This is a serious problem for precision instruments that use tables.

  Conventionally, in order to cope with this problem, it is conceivable to increase the width of the slider so that the center of the coil is aligned with the center of gravity of the slider. However, when the acceleration decreases due to the increase in the weight of the slider or when a predetermined stroke is to be obtained, another problem arises that the rail must be extended.

  It is also conceivable to attach a counterweight to the magnetic pole detector side to balance the attractive force. However, in order to balance the suction force, a counterweight of 10 to 20 kg must be attached. In this case, the acceleration decreases due to an increase in the weight of the slider.

  As described above, none of the methods provides a radical solution to the problem of non-uniform bearing clearance due to the slider center and coil center not matching.

  Accordingly, an object of the present invention is to solve the problems of the prior art and to evenly correct the bearing gap between the air bearing and the guide rail even if the slider center and the coil center do not coincide with each other. Another object of the present invention is to provide an air table device and a bearing interval correction method capable of obtaining high rigidity.

In order to achieve the above object, the present invention comprises a rail having a T-shaped cross section in which a horizontal portion and a vertical portion have a T shape, and a magnet is arranged in the longitudinal direction in the center on the upper surface of the horizontal portion. When,
A slider that has a lateral air bearing that opposes the left and right side surfaces of the vertical portion of the guide rail, and an upper air bearing and a lower air bearing that oppose the upper and lower surfaces of the horizontal portion, respectively, and that travels the guide rail by driving a linear motor. And a suction force generator that is arranged on one side surface of the slider in the running direction and corrects non-uniform bearing spacing between the sliding surface of the slider and each of the air bearings, the suction force generator is Of the coil and magnetic pole detector provided on the inner side surface of the slider main body so as to face the magnet of the guide rail, the slider is arranged on the side surface closer to the magnetic pole detector .

The present invention also includes a rail having a T-shaped cross section in which a horizontal portion and a vertical portion form a T-shape, and a magnet is arranged in the longitudinal direction in the center on the upper surface of the horizontal portion, and the guide rail and the guide rail are perpendicular to each other. An air bearing having lateral air bearings opposed to the left and right side surfaces of the part, and an upper air bearing and a lower air bearing respectively opposed to the upper and lower surfaces of the horizontal part, and a slider that travels the guide rail by a linear motor drive. In the table apparatus, a method of uniformly correcting a bearing interval between the slider and each air bearing , wherein the guide rail is provided on one side surface of the slider in the traveling direction and on the inner side surface of the main body of the slider. of the coil and the magnetic pole detector is opposed to the magnet, the attraction force generating means on the sides closer to the magnetic pole detector disposed, generating a suction force to said suction force generating means So that by, characterized by modifying the non-uniformity of the bearing gap between the sliding surface and the respective air bearing of the slider.

  According to the present invention, even if the slider center and the coil center do not coincide with each other, the bearing gap between the air bearing and the guide rail can be uniformly corrected to achieve high speed and high rigidity.

Hereinafter, an embodiment of an air table device according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a perspective view showing an air table device according to an embodiment of the present invention. In FIG. 1, reference numeral 20 indicates a linear motor driven slider. A table (not shown) is mounted on the slider-20. Reference numeral 22 indicates a guide rail on which the slider 20 travels.

  As the guide rail 22, a rail having a T-shaped cross section in which the horizontal portion 23 and the vertical portion 24 form a T shape is used. A magnet 25 is arranged in the longitudinal direction at the center of the upper surface of the horizontal portion 23 of the guide rail 22.

FIG. 2 shows a cross section of the slider 20. The slider 20 has a structure in which the following air bearings are combined.
Lateral air bearings 26 a and 26 b that are opposed to the left and right side surfaces of the horizontal portion 23 of the guide rail 22 are attached to the left and right sides of the slider 20. Further, the slider 20 is provided with upper air bearings 27a and 27b and lower air bearings 28a and 28b facing the upper and lower surfaces of the horizontal portion 23 of the guide rail 22, respectively. In FIG. 2, reference numeral 21 is a linear scale used for position detection.

  Also, as shown in FIG. 3, one coil 30 and one magnetic pole detector 32 are provided inside the slider 20 as elements of the linear motor, and the coil 30 and the magnetic pole detector 32 are provided as guide rails. 22 is arranged at a position facing the magnets 25 arranged in 22.

  In order to run the slider 20 at high speed, it is necessary to attach a coil 30 having a large capacity. For this reason, the coil 30 also becomes large. In addition, since the coil 30 is attached to the magnetic pole detector 32 in a pair, the center of the coil 30 is eccentric with respect to the center of the slider 20. Due to such eccentricity, an eccentric load is generated, and among the six air bearings provided on the slider 20, in particular, there is variation in the bearing intervals of the upper air bearings 27a and 27b and the lower air bearings 28a and 28b. Arise.

  Therefore, in the air table device of the present embodiment, as shown in FIGS. 1 and 3, in order to correct the non-uniformity of the bearing interval, the suction force generator 34 is provided on the slider-20.

  This attraction force generating portion 34 is made of a ferrous material that generates a magnetic force and an attraction force between itself and a magnet, and is disposed on the side surface 20 a facing the traveling direction of the slider 20. The side surface 20 a to which the attractive force generating unit 34 is attached is the side surface closer to the magnetic pole detector 32.

  Such an attractive force generator 34 generates an attractive force having a size corresponding to the size of the gap between the area and the magnet 25 of the guide rail 22.

The air table device according to the present embodiment is configured as described above. Next, its operation and effect will be described.
FIG. 6 shows an example in which the bearing interval of the air bearing before the suction force generator 34 is attached to the slider 20 is measured. In FIG. 6, the bearing intervals at the four corners of the slider 20 are shown. Here, the upper gap refers to a gap between the upper air bearings 27a and 27b and the upper sliding surface of the horizontal portion 23 of the guide rail 22 in comparison with FIG. The lower gap refers to a gap between the lower air bearings 28 a and 28 b and the lower sliding surface of the horizontal portion of the guide rail 22.

  As described above, when the center of the coil 30 is offset with respect to the center of the slider-20, in FIG. 6, it is slightly inclined so as to become lower toward the right side of the slider-20. For this reason, on the right side of the slider-20, the upper gap becomes smaller and the lower gap becomes larger. On the contrary, on the left side of the slider 20, the upper gap becomes larger and the lower gap becomes smaller.

  Therefore, as in the present embodiment, an attractive force generator 34 is provided on the side surface 20 a of the slider 20, in this case, the higher side surface, to generate an attractive force for the magnet 25. Then, the slider 20 is attracted to the magnet 25 so that the higher one becomes lower, so that the upper gap is small and the lower gap is corrected. On the right side of the slider-20, the upper gap is corrected and the lower gap is reduced. As a result, as shown in FIG. 3, the upper gap and the lower gap of the slider 20 can be made substantially uniform throughout.

  Note that the attractive force of the coil of the attractive force generator 34 is about 0.3 N / mm @ 2 when the gap with the magnet is 0. Therefore, the attractive force is generated using the relationship of the area of the attractive force generator 34 x the gap. Adjust the size of the so that there is a uniform gap. The shape of the suction force generator 34 may be a square, a triangle, or the like.

  As described above, by providing the slider 20 with the suction force generating portion 34, the slider 20 itself is not changed at all, such as increasing the width or increasing the mass. Since it can be kept uniform, high bearing rigidity can be realized while ensuring high speed.

It is a perspective view which shows one Embodiment of the air table apparatus by this invention. It is a cross-sectional view of the slider of the air table device. It is a top view which shows the arrangement position of the attraction | suction force generation part provided in the air table apparatus by this invention. It is a perspective view which shows the conventional air table apparatus. It is a structure explanatory drawing of the slider of the conventional air table apparatus. It is a top view which shows the variation in the bearing space | interval in the conventional air table apparatus.

Explanation of symbols

20 Slider 22 Guide rail 26a, 26b Lateral air bearing 27a, 27b Upper air bearing 28a, 28b Lower air bearing 30 Coil 32 Magnetic pole detector 34 Suction force generating part

Claims (3)

A horizontal section and a vertical section are each formed of a T-shaped rail having a T-shape, and on the upper surface of the horizontal section, magnets are arranged in the longitudinal direction in the center, and a guide rail;
A slider that has a lateral air bearing that opposes the left and right side surfaces of the vertical portion of the guide rail, and an upper air bearing and a lower air bearing that oppose the upper and lower surfaces of the horizontal portion, respectively, and that travels the guide rail by driving a linear motor. When,
A suction force generating part that is disposed on one side surface of the slider in the running direction and corrects uneven bearing spacing between the sliding surface of the slider and each of the air bearings ;
The attraction force generator is disposed on a side surface closer to the magnetic pole detector among a coil and a magnetic pole detector provided on the inner side surface of the main body of the slider so as to face the magnet of the guide rail. Air table device.   The said attraction force generation | occurrence | production part consists of a plate-shaped iron-type material which generate | occur | produces the attraction force according to the magnitude | size of the clearance gap between the area and the magnet of the said guide rail. Air table device. A horizontal section and a vertical section are T-shaped rails having a T-shape, and a magnet is arranged in the longitudinal direction in the center on the upper surface of the horizontal section, and a guide rail and left and right side surfaces of the vertical section of the guide rail, respectively. In the air table apparatus, comprising: an opposing lateral air bearing; and an slider having an upper air bearing and a lower air bearing respectively opposed to the upper and lower surfaces of the horizontal portion, and running the guide rail by a linear motor drive. Is a method of uniformly correcting the bearing spacing between each air bearing,
One side surface of the slider in the running direction, and is attracted to the side surface closer to the magnetic pole detector among the coil and the magnetic pole detector provided on the inner side surface of the main body of the slider so as to face the magnet of the guide rail. An air table characterized in that a non-uniform bearing spacing between the sliding surface of the slider and each of the air bearings is corrected by arranging a force generating means and generating the suction force by the suction force generating means. A method for correcting a bearing interval in an apparatus.

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