JPH0283407A - Friction feed mechanism - Google Patents

Abstract

PURPOSE:To achieve highly accurate positioning without imparting external force to the guide mechanism of a relative moving member by simple constitution such that the reaction force generated when a friction roller is pressed to a drive shaft is received by the drive shaft and the bearing unit engaged with said shaft. CONSTITUTION:Bearing units 51A, 51B each consisting of the linear ball bearing engaged with the outer peripheral surface of a drive shaft 12 and the radial ball bearing engaged with the outer periphery of said bearing 52 are provided on the side of a table 21 and the reaction forces of the pressing forces generated when friction rollers 37A, 37B are pressed to the peripheral surface of the drive shaft 12 are received by the drive shaft 12 and the bearing units 51A, 51B. By this constitution, it is unnecessary to provide high rigidity to a guide mechanism in order to receive the reaction forces and it is prevented that a twist is generated in the table 21 by the reaction forces of the pressing forces. The resistance generated when the table 21 is moved in the axial line direction of the drive shaft 12 and the resistance generated when the drive shaft 12 is rotated are respectively reduced by the bearings 52, 53 and the smooth movement of the table 21 is ensured to make it possible to achieve highly accurate positioning.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a friction feed Il! using friction rollers. Regarding the structure.

For example, it can be used as a table or head feeding mechanism for measuring machines, machine tools, etc.

[Prior Art] Coordinate measuring machines, machine tools, and the like are configured to relatively move a table on which a work is placed, a probe, or a head that supports a tool using a feeding mechanism.

Conventionally, this type of feed RIM requires highly accurate feed, so a system in which a feed screw such as a ball screw is used to convert the rotational motion of the drive shaft into reciprocating motion in the axial direction is often used. However, this method has the problem of high manufacturing costs because the thread shape formed on the drive shaft must be finished with high precision.

Therefore, a friction roller that is inclined at a predetermined lead angle with respect to the axis of the drive shaft is pressed against the circumferential surface of the drive shaft, and the feed operation is performed using the axial component force of the drive shaft that is generated on the friction roller as the drive shaft rotates. For example, a friction feeding mechanism has been developed that performs
What is shown in FIG. 6 or FIG. 6 has been developed.

The one shown in FIG. 5 includes a relatively movable bed (not shown) and a table 2, with a drive shaft 3 on the bed side.
is rotatably provided along the moving direction of the table 2, and a roller holding member 5 is rotatably attached to the table 2 side via the support member 4 with a support shaft 6 as a fulcrum. A friction roller 7 inclined at a predetermined lead angle with respect to the axis of the drive shaft 3 is rotatably mounted, and the friction roller 7 is pressed against the circumferential surface of the drive shaft 3 between the table 2 and the roller holding member 5. This configuration includes a tension coil spring 8.

In addition, the one shown in FIG. 6 has a support member 4A on the table 2.
, 4B, a pair of roller holding members 5A, 5B are mounted on both sides of the drive shaft 3 and rotatable about support shafts 6A, 6B, respectively.
Friction rollers 7A and 7B are inclined at a predetermined lead angle with respect to the axis of the drive shaft 3 and at the same lead angle.
The friction rollers 7A and 7B are attached to the drive shaft 3 between the roller holding members 5A and 5B.
It has a configuration in which a tension coil spring 8' is provided to press against the circumferential surface of the body.

[Problems to be Solved by the Invention] In the configuration shown in FIG. It will work. This reaction force causes disturbance to the guide mechanism of the table 2, and is a factor that impedes highly accurate positioning. Therefore, conventionally, in order to receive this reaction force, the table 2
Since the guide 81 must have a high degree of regularity, there is a problem in that the mechanism becomes large.

Further, in the configuration shown in FIG. 6, since the pair of friction rollers 7A and 7B are pressed from both sides of the drive shaft 3 by the tension coil spring 8-, the advantage is that their reaction forces cancel each other out and do not act externally. There is. However, such a mechanism requires a pair of friction rollers 7A and 7B, which makes the mechanism complicated. Furthermore, it is extremely difficult to match the lead angles of the friction rollers 7A and 7B with respect to the axis of the drive shaft 3 in the zero friction roller 7A.

If the lead angle of 7B deviates even slightly, a lead error will occur and slippage will occur with respect to the drive shaft 3, so that not only high precision positioning cannot be expected, but there will also be a problem in durability.

SUMMARY OF THE INVENTION The object of the present invention has been to solve these conventional problems, and to provide a system with a simple configuration that can achieve highly accurate positioning without applying external force to the guide of a relative moving member. The object of the present invention is to provide a friction feeding mechanism.

[Means for Solving the Problems] Accordingly, the present invention is configured such that the reaction force generated when the friction roller is pressed against the drive shaft is received by the drive shaft and a bearing unit fitted thereto.

Specifically, a drive shaft is provided on one of the two relatively movable members so as to be rotatable along the direction of relative movement, and a friction roller is rotatably provided on the other of the two relatively movable members and its rotation axis. is arranged to be inclined at a predetermined lead angle with respect to the axis of the drive shaft, and the friction roller is provided with a biasing means for pressing the friction roller against the circumferential surface of the drive shaft. The other of the two members is a bearing that is fitted on the outer circumferential surface of the drive shaft and allows direct movement in the axial direction of the drive shaft, and a bearing that is fitted on the outer circumference of the bearing and is centered on the axis of the drive shaft. A bearing unit comprising a bearing that allows rotation is arranged to sandwich the friction roller.

[Function] When the drive shaft is rotated, the friction roller rotates following the rotation of the drive shaft. Then, the two members are moved relative to each other by a component force of the friction roller in the direction of the drive shaft. At this time, the reaction force when the friction roller is pressed against the circumferential surface of the drive shaft is received by the bearing unit and the drive shaft, so the reaction force is applied to the guide 8 of the relative moving member! There is no side effect.

Therefore, the guide mechanism does not need to have a high degree of opening in order to receive the reaction force, and it is not necessary to use a plurality of friction rollers, so that the structure can be small and simple.

In addition, since the bearing units are placed on both sides of the friction roller, the relatively moving member does not twist due to the reaction force of the pressing force, and it only needs to receive half of the reaction force. Moreover, the resistance to linear movement of the relative movement member in the direction of relative movement and rotation of the drive shaft is also reduced by each bearing of the bearing unit.
Highly accurate positioning can be achieved.

Embodiments] The present invention will be described in detail below based on embodiments shown in FIGS. 1 to 4.

This embodiment is an example applied to a table feeding device of a measuring machine, here a microscope, and as shown in FIG. 1, a table 21 is provided with respect to a bed 11 so as to be movable back and forth in the left and right directions in FIG. There is.

One side of these two relatively moving members, here the bed 1
On the 1 side, a drive shaft 12 is rotatably provided along the reciprocating direction of the table 2. Drive shaft 12
is rotatably supported by bearings 13 (the left end in FIG. 1 is not shown) provided on the bed 11 at both ends, and is rotationally driven by a motor 14 connected to one end.

On the other hand, a mounting member 22 is attached to the table 21 side. As shown in detail in FIG. 4, the mounting member 22 has two
A support substrate 25 is attached via two plate springs 23, 24. The first leaf spring 23 is attached to the distal end surface of the attachment member 22 so that its thickness direction is parallel to the axis of the drive shaft 12 and perpendicular to the axis (X direction). There is. In other words, it is attached so that it can be displaced in the X direction. The second leaf spring 24 is attached to the support substrate 25 via a mounting member 26, so that the thickness direction thereof is parallel to the axis of the drive shaft 12 and perpendicular to the axis and the X direction (Y direction). Installed to match. In other words, the 0
Both end portions of both leaf springs 23 and 24 are L-shaped connecting members 27A.

27B. Therefore, the support substrate 25 is
The plate springs 23 and 24 can be displaced in the X direction and the Y direction, respectively.

A pair of movable plates 3IA and 31B are respectively attached to the front end side of the support substrate 25, that is, the front end side parallel to the axis of the drive shaft 12, on the opposite side of the table 21 with the drive shaft 12 in between. Each movable grate 31A, 31B is attached to a bracket 32 attached to the support substrate 25 via a plate spring 33 so as to be tiltable toward and away from the drive shaft 12. In other words, it is mounted so as to be tiltable using the leaf spring 33 as a fulcrum.

Friction roller units 34A and 34B are attached to each movable grate 31A and 31B, respectively.

Each friction roller unit 34A, 34B includes U-shaped roller holding frames 35A, 35B attached to the movable plates 31A, 31B, and roller holding frames 35A, 35B.
The friction rollers 37A and 37B have a deep-dipped ball bearing structure and are rotatably supported via shafts 36A and 36B. Thrust bearings 38 are interposed on both sides of the friction rollers 37A and 37B.

Here, each r'J rubbing roller unit 34A, 34B is
As shown in FIG. 3, each friction roller 37A, 37
The rotation axis of the drive shaft 12 has a lead angle θ1.B relative to the axis of the drive shaft 12. It is installed at an angle of θ2 (θ1 × θ2). In other words, each friction roller 37A,
37B axis 36A.

36B respectively have a lead angle θ1. It is installed at an angle of θ2 (θ1 × θ2).

Further, holding plates 40 are provided on both sides of the support substrate 25.
A connecting member 41 is spanned between the zero-car holding grates 40A and 40B, which are attached at right angles to the axis of the drive shaft 12. The connecting member 41 includes
Bolts 42 inserted from the outside of each of the movable plates 35A and 35B (the bolts on the right side in FIG.
is inserted at right angles to the axis of the A nut 44 is screwed into the threaded portion of the bolt 42 with a washer 43 interposed therebetween. Bolt 42 between washer 43 and connecting member 41
A spring 45 serving as a biasing means for pressing each of the friction rollers 37A, 37B against the circumferential surface of the drive shaft 12 is wound around the portion. Due to the action of the spring 45, the movable play)-3
5A and 35B are tilted counterclockwise in FIG. Note that 46 is a piezoelectric element provided on the support substrate 25 to face the movable plates 31A, 31B of each friction roller unit 34A, 34B. When the piezoelectric element 46 is energized, the movable plate 31A,
31B rotates clockwise in FIG. 2 against the spring 45, each friction roller 37A, 37B can be separated from the circumferential surface of the drive shaft 12.

Moreover, bearing units 51A and 51.8 are built in each of the connecting members 40A and 40B, respectively. That is, the bearing units 51A and 51B are arranged with the II rubbing rollers 37A and 37B interposed therebetween. Each bearing unit 51A, 51B includes a linear ball bearing 52 that is fitted on the outer circumferential surface of the drive shaft 12 and allows direct movement of the drive shaft 12 in the axial direction; Radial ball bearing 53 that allows rotation about the axis of drive shaft 12
It is composed of.

Next, the operation of this embodiment will be explained.

(Fine feed) To finely feed the table 21 with respect to the bed 11,
The piezoelectric element 46 on the friction roller unit 34B side is energized. As a result, when the piezoelectric element 46 is displaced, the movable plate 31B tilts clockwise in FIG.

In other words, only the friction roller 37A is pressed against the circumferential surface of the drive shaft 12 by the action of the spring 45.

Therefore, in this state, the drive shaft 1 is
When the table 21 is rotated, the friction roller 37A rotates following the rotation of the drive shaft 12, so that the table 21 has a lead angle θ.
1 (where d is the diameter of the drive shaft 12). In other words, the table 21 can be slightly moved relative to the bed 11 at the feed pitch P1.

(High-speed feed) To feed the table 21 at high speed with respect to the bed 11,
The piezoelectric element 46 on the friction roller unit 34A side is energized. As a result, when the piezoelectric element 46 is displaced, the movable plate 31A tilts clockwise in FIG.

In other words, only the friction roller 37B is pressed against the circumferential surface of the drive shaft 12 by the action of the spring 45.

Therefore, in this state, the drive shaft 1 is
When the table 21 is rotated, the friction roller 37B rotates following the rotation of the drive shaft 12, so that the table 21 has a lead angle θ.
2 (where d is the diameter of the drive shaft 12). In other words, the table 21 can be fed at high speed with respect to the bed 11 at the feed pitch P2.

(Floating) Both friction roller units 34A, 3
When the piezoelectric element 46 of 4B is energized, both friction rollers 37A
, 37B are separated from the circumferential surface of the drive shaft 12, that is, both lI! Since the pressing force of the rubbing rollers 37A and 37B becomes 0, the table 21 can be manually moved to the free position.

Therefore, according to the present embodiment, bearing units 5IA and 51B are provided on the table 21 side, which are composed of a linear ball bearing 52 that fits on the outer circumference of the drive shaft 12 and a radial ball bearing 53 that fits on the outer circumference of the linear ball bearing 52. Therefore, the reaction force of the pressing force generated when the friction rollers 37A, 37B are pressed against the circumferential surface of the drive shaft 12 can be received by the drive shaft 12 and the bearing units 51A, 51B. It is not necessary to provide high rigidity on the side of the guide tR to receive the reaction force as in the past, and
Since a plurality of friction rollers may be used, the structure can be made small and simple.

In addition, since the bearing units 51A and 51B are arranged on both sides of the friction rollers 37A and 37B, the table 21 does not twist due to the reaction force of the pressing force, and the reaction force can be reduced by 1/2. All you have to do is take it.
Furthermore, each bearing unit 51A, 51B includes a linear ball bearing 52 and a radial ball bearing 53.
Therefore, the resistance when the table 21 moves in the axial direction of the drive shaft 12 is reduced by the linear ball bearing 52, and the resistance when the drive shaft 12 rotates is reduced by the radial ball bearing 53. . Therefore, since smooth movement of the table 21 can be guaranteed, highly accurate positioning can be achieved.

In addition, the support substrate 25 is attached to the table 21 via two leaf springs 23 and 24, and the bearing units 51A and 51B are provided on this support substrate 25. In other words, the support substrate 25 and the bearing units 51A and 51B are Two directions perpendicular to each other with respect to the table 21 (drive shaft 1
Since it is mounted so that it can be displaced in the X and Y directions perpendicular to the axis of the drive shaft 12, it can also follow the whirling of the drive shaft 12.

Also, different lead angles θ1.
Two friction rollers 37A and 37B of θ2 are provided, and these are pressed against the circumferential surface of the drive shaft 12 by a spring 45, and each friction roller 37A.

37B is displaced in a direction away from the circumferential surface of the drive shaft 12 by the piezoelectric element 46. Therefore, if the piezoelectric element 46 is energized to separate the III roller 37B from the drive shaft 12, fine movement can be achieved, and the friction roller 37A can be moved away from the drive shaft 12. If they are separated from the drive shaft 12, they can each be switched to high-speed driving. Further, by separating both friction rollers 37A and 37B from the drive shaft 12, the table 21 can be manually moved to the free position. Therefore, these switching operations are also extremely simple since it is only necessary to control the energization to the piezoelectric element 46.

Note that in the above embodiment, the lead angle θ1. 2 different θ2
Although two friction rollers 34A and 34B are provided, the number of friction rollers may be one, or may be increased as appropriate depending on the number of steps of the required feed speed, etc. Furthermore, the lead angle set for each may also be finely adjusted. Not limited to transportation and highways,
It may be adjusted as appropriate.

Further, when a plurality of friction rollers are provided, the arrangement of these friction rollers is not limited to the arrangement along the drive shaft 12 as in the above embodiment, but may be changed as appropriate.

For example, the friction rollers may be arranged facing each other on both sides of the drive shaft 12, and the friction rollers are not limited to two opposing positions, but may be arranged at any angular position, or at a predetermined position of the drive shaft 12. Three or more friction rollers may be arranged around the circumferential direction.

Furthermore, the axial arrangement and the circumferential arrangement may be combined. For example, if an arrangement such as three rows of two friction rollers in each circumferential direction along the drive shaft 12 is adopted, the arrangement can be made compact. In addition, the degree of freedom in design can be increased.

Further, in the above embodiment, the movable plates 31A, 31B are tilted by energizing the piezoelectric element 46, and the friction rollers 37A, 37B are separated from the circumferential surface of the drive shaft 12. A solenoid or air cylinder may also be used.

Note that the present invention is not limited to the table feeding device for a microscope described in the above embodiment, but can be applied to, for example, a feeding mechanism of two members that move relative to each other, such as a machine tool or an image processing device.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a friction feed mechanism that has a simple configuration and can achieve highly accurate positioning without applying external force to the guide R structure of a relatively moving member. Can be done.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention.
The figure is a plan view with some of the main parts cut away, Figure 2 is a sectional view taken along the line ■-■ in Figure 1, Figure 3 is a diagram showing the relationship between the drive shaft and the friction roller, and Figure 4 FIG. 2 is a perspective view showing a connecting portion between the mounting member and the support substrate. FIGS. 5 and 6 are perspective views showing conventional examples, respectively. 11.21... Bed and table (two relatively movable members), 2... Drive shaft, 7A, 37B... R rubbing roller, 5... Spring (biasing means), LA, 51B. ...Bearing unit, 2...Linear ball bearing, 3...Radial ball bearing.

Claims (1)

[Claims] (1) A drive shaft is rotatably provided on one of the two relatively movable members along the direction of relative movement, and a friction roller is rotatably provided on the other of the two relatively movable members, and its rotation axis is In the friction feed mechanism, the friction roller is arranged to be inclined at a predetermined lead angle with respect to the axis of the drive shaft, and is provided with a biasing means for pressing the friction roller against the circumferential surface of the drive shaft. The other member includes a bearing that is fitted on the outer circumferential surface of the drive shaft and allows direct movement in the axial direction of the drive shaft, and a bearing that is fitted on the outer circumference of the bearing and rotates about the axis of the drive shaft. A friction feed mechanism characterized in that a bearing unit comprising a bearing that allows the friction roller to sandwich the friction roller is disposed.