JPH04322929A - Guide mechanism for horizontal free movement - Google Patents

Abstract

PURPOSE:To eliminate a difference in moving resistance among moving directions so as to set a vertical position of an article to be mounted with a high degree of accuracy by arranging more than three of steel balls on the upper and lower surfaces of a movable bed while clamping them between upper and lower horizontal surfaces. CONSTITUTION:A movable bed 2 fixed at the center of a work stage 1 is set on a lower guide surface 4a of a guide casing 4 through the intermediary of lower steel balls 3. A lower guide plate 5 prevents the lower balls 3 from coming off from the surface of the movable bed 2 and deviating from the normal positions of the balls. Similarly, upper steel balls 7 adapted to be guided by an upper guide plate 6 are laid on the upper surface of the movable bed 2 in order to retrain the vertical movement of the movable bed 2. Movable blocks 9a, 9b, 9c, 9d arranged around the movable bed 2 and about a movable original point 11 are moved toward the center of a guide mechanism by means of drive mechanisms 10a, 10b, 10c and 10d each composed of an air cylinder and a piston. When no load is applied to the movable bed 2, the movable bed 2, the lower guide plate 5 and the upper guide plate 6 are returned to the movable original point.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a guide mechanism in a positioning device used, for example, in an optical measuring device, a precision assembly device, etc., which allows a movable stage for fixing a loaded object to move freely on a horizontal plane. The present invention relates to the configuration of a horizontal free movement guide mechanism.

0002

[Prior Art] When positioning a loaded object mounted on the stage of a moving table, it is possible to maintain the vertical positional accuracy of the loaded object while maintaining horizontal positioning using only a minute external force applied to the loaded object. A movable table that can freely move in the XYΘ directions on a plane is required.

FIG. 2 is an explanatory diagram showing the configuration of the simplest horizontal free movement guide mechanism (hereinafter also simply referred to as guide mechanism) using a lubricating sheet in the sliding part, as a first example of the prior art. . In the figure, a lower lubricating sheet 22 made of, for example, tetrafluoroethylene resin is attached to a horizontal movement guide surface 21a of a guide case 21, and a moving table 23 is placed on top of the lower lubricating sheet 22. Further, a guide cover 25 to which an upper lubricating sheet 24 is attached is fixed to the guide case 21 to restrain the upward movement of the moving platform 23 and to guide the horizontal movement. A work table 26 on which the loaded object is fixed is fixed to the movable table 23.

[0004] FIG. 3 is an explanatory diagram showing the configuration of a guide mechanism example including guide members for different directions of movement, as a second example of the prior art. In the figure, a Y axis guide member in the Y axis direction is mounted on an X axis linear slide 31 which is a guide member in the X axis direction.
The shaft linear slides 32 are mounted perpendicularly to each other, and a rotary bearing 33 is further mounted thereon. A moving table integrated with the work table 34 is fixed to the inner ring of the rotary bearing 33.

[0005]

[Problems to be Solved by the Invention] However, in the first example of the prior art, since the friction between the moving table and the guide mechanism is sliding friction, the weight of the object mounted on the stage is greater than the sliding resistance. In addition, since a certain amount of clearance is provided between the guided surface of the movable base and the lubricating sheet in order to move the movable base smoothly, there are problems such as a lack of accuracy in the vertical direction.

[0006] Furthermore, in the second example of the prior art, the first
Although the problem in the above example has been solved, the structure becomes complicated and becomes an expensive mechanism. Furthermore, since there is a difference in sliding resistance depending on the direction of movement, there is a problem that smooth movement is not possible.

[0007] An object of the present invention is to provide a configuration of a guide mechanism that can be manufactured at low cost and that does not cause a difference in movement resistance depending on the direction of movement of the moving table, and that allows the vertical positioning of a loaded object to be set with high accuracy. The goal is to provide the following.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a horizontal free movement guide mechanism that allows a moving platform for fixing a loaded object to move freely on a horizontal plane. Three or more steel balls are placed on the upper and lower surfaces of the movable base to move the movable base in the horizontal direction while restraining the vertical movement, and the steel balls are connected to the upper and lower surfaces of the movable base, respectively. an upper guide plate and a lower guide plate held on top; a guide case having a lower horizontal movement guide surface that accommodates the steel balls, the upper guide plate, and the lower guide plate; a guide cover having an upper horizontal movement guide surface that restrains the upward movement of the movable base; a movable block for returning the movable base, the upper guide plate, and the lower guide plate to the movement origin positions; and a movable block for moving the movable block. The configuration includes a drive unit that causes the

In the guide mechanism configured as described above, flat plates having a thickness larger than the radius of the steel ball and smaller than the diameter thereof are used as the upper guide plate and the lower guide plate for holding the steel balls on the upper and lower surfaces of the movable table, respectively. It is preferable to use a hole in which the steel ball can enter, and the same number of holes of approximately the same diameter as the steel balls are formed.

Furthermore, movable blocks for returning the movable table, upper guide plate, and lower guide plate to the movement origin positions are arranged at 90° intervals centering on the movement origin, and when returning, the movable blocks return the movable table, the upper guide plate, and the lower guide plate to the movement origin positions. If the width of the contact surface of the movable block that comes into contact with the plate is made to be at least twice the maximum movable distance of the movable base from the movement origin position, and the movable block is driven in the direction passing through the movement origin. It is even more suitable.

[0011]

[Operation] If the horizontal free movement guide mechanism is configured in this way, the movement resistance when moving the moving table becomes rolling friction between the moving table and the upper and lower horizontal movement guide surfaces, and the movement according to the direction of movement is reduced. Since there is no difference in resistance, movement can be performed smoothly in either direction. In addition, smooth movement can be achieved even when the guide mechanism is assembled so that there is no gap between the steel balls and the upper horizontal movement guide surface, so the vertical position of the loaded object can be set on either surface of the guide mechanism. The position can be set with high precision. In addition, since the movable base can be moved in any direction simply by arranging steel balls in a single layer on the upper and lower sides of the movable base, the guide mechanism becomes simple and compact.

[0012] As the upper and lower guide plates in the guide mechanism constructed in this manner, a hole approximately the same diameter as the steel ball is formed into a flat plate having a thickness larger than the radius of the steel ball and smaller than the diameter. By using steel balls formed in the same number as balls, it is possible to always hold a plurality of steel balls on the surface of the moving table and always maintain the optimum spacing between the steel balls without using a special holding member. Can be done.

Furthermore, movable blocks for returning the movable table, upper guide plate, and lower guide plate to the movement origin positions are arranged at 90° intervals centering on the movement origin, and when returning, the movable blocks, the upper guide plate, and the lower guide plate return to the movement origin positions. If the width of the contact surface of the movable block that comes into contact with the plate is made to be at least twice the maximum movable distance of the movable base from the movement origin position, and the movable block is driven in the direction passing through the movement origin. Regardless of whether the movable base is rectangular or circular, the movable block and drive unit can be used in common to return the movable base to the movement origin position, reducing the number of parts of the guide mechanism.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the structure of a horizontal free movement guide mechanism according to the present invention. In the figure, a movable table 2 on which a work stage 1 to which a load (not shown) is attached is fixed at the upper center thereof is placed on a lower guide surface 4a of a guide case 4 via a lower steel ball 3. The lower guide plate 5 serves as a guide to prevent the lower steel balls 3 from falling off the surface of the movable table 2 and from being misaligned. For the same purpose, an upper steel ball 7 guided by an upper guide plate 6 is disposed on the upper surface of the movable base 2, and an upper guide surface 8a of a guide cover 8 is disposed on top of the upper steel ball 7, so that the upper surface of the movable base 2 is Movement is restricted. Note that the guide cover 8 is adjusted so that the gap between it and the upper steel ball 7 is minimized. Around the moving table 2,
90 degrees around the movement origin 11 which is the center of the guide mechanism
Movable blocks 9a, 9b, 9c, 9 arranged at intervals
d is a drive mechanism 10 consisting of an air cylinder and a piston.
a, 10b, 10c, and 10d to move toward the center of the guide mechanism and return the movable base 2, lower guide plate 5, and upper guide plate 6 to the movement origin position when no load is applied to the movable base 2. doing. This movable block 9
Due to a, 9b, 9c, and 9d, when the movement is repeated, the lower guide plate 5 and the upper guide plate 6 come into contact with the inner surface of the guide case 4, and the rolling resistance of the lower steel ball 3 and the upper steel ball 7 increases. It prevents you from doing so.

[0015]

Effects of the Invention In the present invention, since the horizontal free movement guide mechanism is constructed as described above, the following effects can be obtained.

In the guide mechanism of claim 1, the movement resistance when moving the movable table becomes rolling friction between the movable table and the upper and lower horizontal movement guide surfaces, so that there is no difference in movement resistance depending on the direction of movement. Therefore, movement can be performed smoothly in any direction. In addition, smooth movement can be achieved even when the guide mechanism is assembled so that there is no gap between the steel balls and the upper horizontal movement guide surface, so the vertical position of the loaded object can be set on either surface of the guide mechanism. The position can be set with high precision. Also,
The movable base can be moved in either direction simply by arranging steel balls in a single layer on the top and bottom sides of the movable base, making the guide mechanism simple and compact, and the manufacturing cost low. Become.

[0017] With the guide mechanism of the second aspect, a plurality of steel balls can be held at low cost with simple members and always on the surface of the movable table while always maintaining the optimum spacing between the steel balls. Stable movement is always possible even if the weight of the object changes.

[0018] In the guide mechanism according to claim 3, the movable table has a rectangular shape;
In both circular cases, the movable block and drive unit common can return the movable base to the movement origin position, and the number of types of parts of the guide mechanism is reduced, so the cost of the guide mechanism is reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the configuration of a horizontal free movement guide mechanism according to the present invention, and FIG.
A cross-sectional view taken along the line B, and (b) is a cross-sectional view taken along the line A-A in the same figure (a).

FIG. 2 is a diagram showing an example of the configuration of a conventional horizontal free movement guide mechanism, in which FIG. 2(a) is a top view and FIG. 2(b) is a side sectional view.

FIG. 3 is a diagram showing another example of a conventional horizontal free movement guide mechanism, in which FIG. 3(a) is a top view and FIG. 3(b) is a side partial sectional view.

[Explanation of symbols] 2 Moving base 3 Steel ball 4 Guide case 4a Guide surface (lower horizontal movement guide surface) 5 Lower guide plate 6 Upper guide plate 7 Steel ball 8 Guide cover 8a Upper horizontal movement guide surface 9a Movable block 9b Movable block 9c Movable block 9d Movable block 10a Drive unit 10b Drive unit 10c Drive unit 10d Drive unit 11 Movement origin 23 Movement base 34 Movement base

Claims (3)

[Claims] Claims: 1. A horizontal free movement guide mechanism that allows a movable platform for fixing a loaded object to move freely on a horizontal plane, wherein the movable platform is moved horizontally while restraining vertical movement; three or more steel balls arranged on the upper and lower surfaces of the moving table, respectively, an upper guide plate and a lower guide plate that hold the steel balls on the upper and lower surfaces of the moving table, respectively; the steel balls; A guide case with a lower horizontal movement guide surface that accommodates the upper guide plate and the lower guide plate, and an upper horizontal movement guide surface that is fixed to the guide case and restrains the upward movement of the moving table via steel balls. A horizontal free movement guide mechanism comprising a guide cover, a movable block for returning the movable table, the upper guide plate, and the lower guide plate to their movement origin positions, and a drive unit for moving the movable block. 2. In the horizontal free movement guide mechanism according to claim 1, the upper guide plate and the lower guide plate that hold the steel balls on the upper and lower surfaces of the moving table, respectively, have a diameter larger than the radius of the steel balls. A horizontal free movement guide mechanism characterized by having the same number of holes with approximately the same diameter as the steel balls, in which the steel balls are inserted into a flat plate with a smaller thickness. 3. In the horizontal free movement guide mechanism according to claim 1, the movable block for returning the movable table, the upper guide plate, and the lower guide plate to the movement origin position is arranged at 90° intervals around the movement origin. The width of the contact surface that contacts the movable base, the upper guide plate, and the lower guide plate upon return is at least twice the maximum movable amount of the movable base from the movement origin position, and passes through the movement origin. A horizontal free movement guide mechanism characterized by being driven in a direction.