JPH08184360A - Frictional forward and backward movement drive device - Google Patents

Abstract

PURPOSE: To use a frictional forward backward movement drive device as a precision apparatus, such as an optical disc mastering device, by a method wherein the device is formed integrally with a contact type high rigidity forward backward movement device, disturbance resistance is high, unevenness in a speed does not occur, a stable feed is practicable, and static performance during the stop of a drive source is improved. CONSTITUTION: A frictional forward backward movement drive device comprises a shaft body 1; and a forward backward movement part 2 to cause the shaft body 1 to relatively rotatably and movably forward and backward extend through the shaft body 1. The forward backward movement part 2 consists of a plurality of rollers 4 in a beer drum-form shape which are brought into rolling contact with the shaft body 1 and peripherally arranged in the body 3. The roller 4 has two end faces which are rotatably supported through a ball 8 between the forward backward movement part body 3 and a pressurization plate 5. At least one of the forward and backward movement part body 3 and a roller end face and at least one of the pressurization plate 5 and the roller end face supports the ball 8 by means of a ball support recessed part 9 in a conical surface shape in which the ball 8 is rotatably fitted in. Further, a resilient body 6 is provided to energize the pressurization plate 5 against the roller 4 side and energize in a peripheral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction advancing / retreating drive device for advancing / retreating an advancing / retreating component by rotating a shaft, and is used, for example, as a positioning unit for precision devices such as an optical disc mastering device and a semiconductor inspection device. The present invention relates to a friction advancing / retreating drive device capable of highly accurate and highly rigid stable feed.

[0002]

2. Description of the Related Art Conventionally, a ball screw has been generally used as a device for converting a rotary motion into a linear motion, and there is an air slide device as a highly accurate forward / backward drive device. These are properly used according to their characteristics, but in equipment that requires a high degree of precision, satisfactory performance in various performance aspects has not been obtained as follows. a) For the positioning unit of the optical disc mastering device. In order to master the master of the optical disc, a feeding mechanism with extremely small speed unevenness and high positioning accuracy is required. For this reason, an air slide device is used for guidance, a voice coil type linear motor is used for drive, and a complete non-contact closed loop control system using a laser interferometer as a position detector is adopted. b) In the case of a positioning unit used in a semiconductor inspection device or the like. It is a positioning unit for observing semiconductor patterns with a high-magnification electron microscope.It can be fed with high precision in a vacuum, and it is necessary to maintain a stationary state for observing the work after positioning is completed. is there. Therefore, the ball screw drive is used, and the power is turned off to suppress the influence of the vibration of the motor when observing the work.

However, in the air slide device of the above a), since it is completely non-contact, there is no slippage, and since there is no drive resistance, high accuracy can be realized, but on the other hand, the drive thrust of the linear motor is small and It is vulnerable to disturbance vibration due to no physical contact. In the case of an optical disc mastering device, the influence of this disturbance appears as track pitch unevenness. In the case of b) above, the ball screw may slightly move in the direction in which the torque is released when the drive motor is stopped due to an error in the groove shape or the ball diameter. Also,
The same problem as described above may occur when the balls are displaced due to the heat generated by the differential sliding of the balls or when the heat is gradually cooled. Further, when the ball moves in and out of the circulation part of the ball, speed irregularity is generated such that the ball moves in the axial direction while vibrating, which is said to be "dirty".

As the other forward / backward drive device, a friction drive type device shown in FIG. 4 has been proposed and put to practical use in a semiconductor manufacturing apparatus or the like. This is one in which a plurality of cylindrical roller bearings 53 are respectively attached to the front and rear ends of an advancing / retreating component 52 penetrating the shaft body 51 in a slanted manner. By rotating the shaft body 51, the cylindrical roller bearings 53 are inclined with respect to the shaft body 51. Thrust is applied to the cylindrical roller bearing 53. An adjusting screw (not shown) such as an adjusting screw or an elastic body is used to press the roller bearing 53. However, the friction advancing / retreating drive device of the same figure requires a large number of roller bearings 53 and its adjusting parts, and therefore has a large number of parts and a complicated structure, and it is difficult to pursue satisfactory accuracy in terms of positioning accuracy. I think that the.

The present invention solves the above problems and provides a contact type high-rigidity advancing / retreating device, which has a high resistance to disturbance, has no speed unevenness, can perform stable feeding, and can be used when the drive source is stopped. An object of the present invention is to provide a friction advancing / retreating drive device capable of improving static performance.

[0006]

A friction advancing / retreating drive device according to the present invention comprises a shaft and an advancing / retreating component which penetrates the shaft so as to rotate and advance / retreat relatively. To do. That is, in the advancing / retreating component body, a plurality of barrel-shaped rollers rollingly contacting the shaft body are arranged side by side in the circumferential direction of the shaft body. It is rotatably supported between the pressure plate and the preload plate. At least one of the advancing / retreating component body and the roller end surface, and at least one of the preload plate and the roller end surface support the ball in a conical surface-shaped ball supporting recess into which the ball is rotatably fitted. Further, an elastic body is provided which urges the preload plate toward the roller and also urges the preload plate in the circumferential direction.

[0007]

Each roller is supported by balls in the conical surface-shaped ball support concave portion and is preloaded in the circumferential direction of the shaft body by the elastic body through the preload plate. It is pressed with the shaft center slightly tilted. Therefore, when the shaft body is rotated, the roller rotates with a lead angle corresponding to the inclination angle, and the advancing / retreating component moves in the axial direction due to the frictional force of the pressing portion.
The advancing / retreating component is supported by an appropriate guide so as to be able to advance / retreat in parallel with the shaft body, and is used in a state in which the rotation of the shaft body is stopped. Although it is driven by frictional contact in this manner, there is no contact pressure change portion such as the circulating portion of the ball screw and the contact is made in a constant state, so that there is no speed unevenness. Also, since the roller is pressed through the ball and the conical surface-shaped ball supporting recess,
The preload plate has a degree of freedom with respect to the shaft center. for that reason,
Even if there is misalignment between the guide of the advancing / retreating parts and the shaft, it can be absorbed. Further, since the shaft body and the roller have a simple shape and are easy to obtain accuracy, they do not slightly move when the output of the drive source is stopped unlike the ball screw. Even if the roller support portion such as the roller and the ball support recess is worn, the preload loss due to the preload by the elastic body does not occur. further,
Since there is no differential slip of the rollers, less heat is generated compared to ball screws.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view taken along line I-I of FIG. The friction advancing / retreating drive device includes a shaft body 1 having a circular cross section, and an advancing / retreating component 2 that penetrates the shaft body 1. The advancing / retreating component 2 is configured by providing a plurality of rollers 4 rollingly contacting the outer peripheral surface of the shaft body 1, a preload plate 5, and a preload elastic body 6 in the advancing / retreating component body 3. The advancing / retreating component body 3 has a round box shape in which a cylindrical peripheral wall member 3c is assembled between a circular fixing plate 3a and a counter plate 3b each having a loose fitting hole through which the shaft 1 penetrates. It is formed. The fixing plate 3a is provided with a mounting hole 7 for mounting the advancing / retreating component 2 on a driven body such as a movable table in a flange portion protruding from the peripheral wall member 3c. The peripheral wall member 3c is an outward facing step surface 3 formed on the outer periphery of the fixed plate 3a and the counter plate 3b.
They are fitted to aa and 3ba, respectively, and fixed to the counter plate 3b with screws 10. Roller loose fitting recesses 11 formed of axial grooves having arcuate cross sections into which the respective rollers 4 are loosely fitted are formed at a plurality of circumferential positions on the inner diameter surface of the circumferential wall member 3c.

The roller 4 is a barrel-shaped outer surface having a spherical crowning shape, and balls 8, 8 such as steel balls are provided in a partially fitted state at the axial center portions of both end surfaces. The parts of the balls 8, 8 protruding from the roller end surface are fixed plates 3
a and the ball supporting recesses 9 having a conical surface shape respectively formed on the counter plate 3b and supported. The ball fitting recess 12 formed in the roller 4 has a cylindrical hole shape, but may have any hole shape. In addition, the ball 8 is the roller 4
Although it is fixed in the ball fitting recess 12 in a press-fitted state, it may be rotatable in the recess 12. The conical surface-shaped ball support recess 9 is provided on the roller 4 instead of on the side of the fixed plate 3a and the preload plate 3b.
The ball fitting recess 12 may be provided in the a and the preload plate 3b.

The elastic body 6 for preload is constructed by connecting the preload plate 5 to the roller 4
An axial preload elastic body 6A that biases the preload plate 5 and a circumferential preload elastic body 6B that biases the preload plate 5 in the circumferential direction.
Axial preload elastic body 6A and circumferential preload elastic body 6
B is composed of a compression coil spring, and these elastic bodies 6A,
6B are provided at a plurality of positions in the circumferential direction of the shaft body 1, respectively. The axial preload elastic body 6A is inserted across the axial hole 13 provided through the counter plate 3b of the advancing / retreating component body 3 and the bottomed axial hole 14 provided in the preload plate 5, A screw member 15 screwed into the female screw portion of the axial hole 13 prevents the screw hole 15 from coming off. As shown in FIG. 2, the circumferential direction preload elastic body 6B includes a diagonal hole 16 penetrating the peripheral wall member 3c of the advancing / retreating component body 3 and a bottomed diagonal hole 17 provided in the preload plate 5. The screw member 18 is inserted through the screw hole 18 and is screwed into the female screw portion of the diagonal hole 16 to prevent the screw hole 18 from coming off. The diagonal holes 16 and 17 are inclined in the same direction in the circumferential direction with respect to the radial direction of the shaft body 1.

The operation of the above configuration will be described. Each roller 4
Is supported in the conical surface-shaped ball support concave portion 9 via the ball 8 and is preloaded in the circumferential direction of the shaft body 1 by the elastic body 6 via the preload plate 5, so the inclination is emphasized in FIG. As shown, the roller shaft center L is pressed against the shaft center O of the shaft body 1 with a slight inclination. Therefore, when the shaft 1 is rotated, the roller 4 rotates with a lead angle θ corresponding to the inclination angle thereof, and due to the frictional force generated at the pressing point P, the advancing / retreating component 2 moves in the axial direction. Moving. In other words, the pressing point P moves spirally on the outer diameter surface of the shaft body 1 at the lead angle θ. The advancing / retreating component 2 is supported so as to be advancing / retreating in parallel with the shaft 1 by an appropriate guide such as a guide shaft or a guide rail via a driven body to which the advancing / retreating component 2 is attached. It is used with the rotation stopped against.

The friction advancing / retreating drive device is driven by frictional contact as described above, but since there is no contact pressure change portion such as the circulation portion of the ball screw and the contact is made in a constant state, there is no speed unevenness. In addition, the ball 8 and the conical surface-shaped ball supporting recess 9
Since the roller 4 is pressed via the preload plate 5, the preload plate 5
Has a degree of freedom with respect to the axis O of. Therefore, advance / retreat parts 2
Even if there is a misalignment between the guide and the shaft body 1, it can be absorbed. Further, the shaft body 1 and the roller 4 have a simple shape,
Since it is easy to obtain accuracy, it does not move slightly when the output of the drive source is stopped unlike the ball screw. Even if the roller support portion such as the roller 4 and the ball support recess 9 is worn, the preload by the elastic body 6 does not cause the problem of preload loss. The axial backlash is also close to zero. Further, since there is no differential slip of the roller 4, heat generation is smaller than that of a ball screw.

The ability to absorb misalignment as described above is effective when used as a positioning unit of an optical disk mastering device, and the fact that there is no slight movement and little heat generation when the output is stopped is a semiconductor inspection. It is effective when used in the positioning unit of the device. Further, this friction advancing / retreating drive device only needs to be provided with the roller 4 at one location in the axial direction of the shaft body 1, so that the number of parts is small, the structure is simple, and the manufacturing cost is low.

In the above embodiment, the elastic body 6A for axial preload and the elastic body 6B for circumferential preload are provided. However, one elastic body is used to urge both axially and circumferentially. May be. Further, the elastic body for preload may be a leaf spring or a rubber-like elastic body.

[0015]

The friction advancing / retreating drive device of the present invention comprises a shaft body and an advancing / retreating component which penetrates the shaft member so as to be relatively rotatable and advancing / retreating. A plurality of barrel-shaped rolling rollers are provided side by side in the circumferential direction of the shaft body, and these rollers are supported between the advancing / retreating component body and the preload plate via the conical surface-shaped ball-supporting recesses and balls, and the preload is applied. Since an elastic body that urges the plate toward the roller side as well as in the circumferential direction is provided, a contact-type high-rigidity advancing / retreating device can be formed, high disturbance resistance, uniform speed, and stable feeding. The stationary performance when the drive source is stopped can be improved. Moreover, there is little heat generation, and misalignment between the shaft and the guide can be absorbed.

[Brief description of drawings]

FIG. 1 is a cutaway side view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an operation explanatory view.

FIG. 4 is a front view and a side view of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Shaft body, 2 ... Advance / retract part, 3 ... Advance / retract part body, 3a ... Fixed plate, 4 ... Roller, 5 ... Preload plate, 6 ... Elastic body, 6A ... Axial preload elastic body, 6B ... Circumferential preload Elastic body, 8 ...
Ball, 9 ... Ball support recess

Claims (1)

[Claims] 1. A friction advancing / retreating drive device comprising a shaft member and an advancing / retreating component which penetrates the shaft member so as to be relatively rotatable and advancing / retreating, wherein the shaft member is provided in the main body of the advancing / retreating component. A plurality of barrel-shaped rollers that roll and contact are arranged side by side in the circumferential direction of the shaft body, and these rollers are rotatably supported between the advancing / retreating component body and the preload plate via balls at the roller shaft center portions of both end surfaces, At least one of the advancing / retreating component body and the roller end surface,
And at least one of the preload plate and the roller end surface,
A friction advancing / retreating drive device provided with an elastic body for supporting the ball by a conical surface-shaped ball supporting recess into which the ball is rotatably fitted and for urging the preload plate toward the roller side and in the circumferential direction. .