JP3186188B2 - Table feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a table feeder, and more particularly to an improvement in accuracy of a table feeder having a table movable in one axis direction by a feed screw and a nut mechanism.

[0002]

2. Description of the Related Art Generally, machine tools, measuring machines, robots,
Precision positioning table feeders used in semiconductor manufacturing equipment, etc., have a configuration in which a nut that is screwed into a feed screw is engaged with a moving table that can move in only one direction with respect to the base. Many. That is, the moving table is supported by a linear guide provided on the base, and is configured to be able to reciprocate only in one direction, and a nut screwed into a feed screw parallel to the linear guide is engaged with the table. By driving the feed screw with a motor, forward and backward movement of the moving table can be realized. in this case,
If the nut and the moving table are fixed, the simplest configuration can be obtained. However, the effect of the bending of the feed screw is directly transmitted to the moving table, which causes a decrease in the feeding accuracy.

[0003] Therefore, in the conventional apparatus, a configuration is adopted in which a feeding nut is engaged with the moving table by regulating only the feeding direction. In this case, there has been proposed a table feeder provided with a mechanism that is more forgiving to the fall of the nut by engaging the nut and the moving table via a hydrostatic thrust bearing. For example, in the conventional device shown in FIG. 4 (Japanese Patent Laid-Open No. 57-25559), a flange 51 is provided coaxially with a nut 51 screwed to a feed screw 50.
The receiving surface 52a projects from the outer peripheral surface of the nut 51. Further, the moving table 53 is provided with a housing H having a circumferential groove 54 into which the flange body 52 is loosely fitted, and a bearing surface 54a is provided in the circumferential groove 54 on a side facing the receiving surface 52a. ing.

[0004] A circumferential groove-shaped bearing pocket P for guiding a pressurized fluid is provided on a bearing surface 54a facing the receiving surface 52a of the flange body 52 to regulate the movement of the receiving surface 52a in the thrust direction. It constitutes a hydrostatic bearing. Thereby, the nut 51 is connected to the housing H by the feed screw 50.
Are supported with rigidity only in the axial direction of.

[0005] The nut 5 with respect to the axis of the feed screw 50 is provided.
1 is prevented by the bellows 55 which can expand and contract in the axial direction.

[0006]

The above-mentioned conventional table feeder has a receiving surface 52 for increasing the rigidity in the feed direction.
If we try to increase the bearing area by increasing the diameter of a,
When the feed screw 50 falls down, a large moment is applied to the housing H, and the influence is increased. For this reason, the influence of the misalignment of the feed screw cannot be completely eliminated, which has been a bottleneck in improving the feed accuracy.

Further, since the bellows 55 has low torsional rigidity, the rotation of the bellows 55 with respect to the nut 51 is not perfect, and this also hinders an increase in accuracy. SUMMARY OF THE INVENTION In view of the above, the present invention provides a table having high rigidity in a feed direction, and a means capable of flexibly absorbing bending of a feed screw and inclination of a nut and transmitting only a pitch operation of a feed screw to a moving table. It is intended to provide a feeding device.

[0008]

According to a first aspect of the present invention, there is provided a moving table guided so as to be movable in one direction with respect to a base; a nut provided on the moving table; A feed screw having an axial center in the moving direction of the moving table and screwing with the nut, and rotating the feed screw to position the moving table at a desired position with respect to the base. Table feeder,
An engagement means for restricting the nut in the axial direction of the feed screw and around the screw axis to engage with the moving table ; and a rotation center on the axis of the feed screw;
A first spherical bearing fixed to the base so as not to move in the direction and axially supporting at least one portion of the feed screw;
A rotation center on the axis of the feed screw;
Move with the moving table and the nut in the axial direction of
And a second spherical bearing that is fixed to the moving table so as to support the nut, and prevents the feed screw or nut from swinging (yawing, pitching) due to the bending of the feed screw by two pieces. It is designed to be absorbed by a spherical bearing. The invention according to claim 2 is the invention according to claim 1, wherein the engaging means is rotatable about a pitch axis orthogonal to a feed axis of the feed screw, and a static pressure, which is provided on the nut provided on the nut. A rotary member provided on the moving table via a bearing, and a groove in the feed axis direction formed on the rotary member, and a tip of the button member with respect to a yaw axis orthogonal to the pitch axis. It is swingably loosely fitted. According to a third aspect of the present invention, in the first aspect, at least one of the first spherical bearing and the second spherical bearing is a hydrostatic bearing. Further, according to a fourth aspect of the present invention, in the first aspect, the first spherical bearing and the second spherical bearing are provided.
At least one of the spherical bearings is a ball bearing. Further, in the invention of claim 5, the nut and the feed screw are constituted by a ball screw mechanism.

Here, in order to prevent the nut from rotating around the axis of the feed screw, the nut is provided with a vignetting (turning) member that protrudes in the radial direction. Can rotate around the perpendicular drawn down from the feed screw shaft to the feed screw shaft. ・ It can swing in the feed screw axis direction (around the line parallel to the surface of the button member and perpendicular to the feed screw shaft). ・ Rotation around the feed screw shaft What is necessary is just to support on a moving table side so that it may become impossible.

[0010]

When the drive motor rotates the feed screw, the nut starts moving along the feed screw axis. At this time, even if the feed screw is bent, at least one portion of the feed screw is configured to be able to swing spherically by the first spherical bearing, so that the fall of the feed screw with respect to the base is absorbed.
Also, the nut swings the attitude with respect to the feed shaft in accordance with the degree of bending of the feed screw, but this change in attitude is absorbed by the second spherical bearing and the knurled member and is not transmitted to the moving table side. Only the pitch feed operation is transmitted to the moving table via the nut, and accurate table feed is realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the accompanying drawings. FIG. 1 is a cross-sectional view showing first and second spherical bearings of the device of the present application, FIG. 2A is a front view showing a holding portion of a button member, and FIG. 3 is a cross-sectional view of an example in which ball bearings are used for the first and second spherical bearings.

In FIG. 1, reference numeral 1 denotes a base of the table feeder of the present invention, and the base 1 is fixed to a floor surface in a clean room, for example. Reference numeral 2 denotes a moving table. The moving table 2 is configured to be movable only in one direction by a linear guide device (not shown) fixed to the base 1. Reference numeral 3 denotes a feed screw. The feed screw 3 is rotatably driven by a motor M provided at one end of the feed screw 3, and can drive the moving table 2 via a nut 4. . R is the rotor of the motor M, S
Is a stator of the rotor M. An encoder, a speed detector, and the like (not shown) are provided at the other end of the feed screw 3.
Can be appropriately attached.

Next, the first spherical bearing will be described. The feed screw 3 is provided in the vicinity 3a of the motor M,
Is supported by a first spherical bearing 10 which is capable of oscillating spherically with respect to a rotation center A on the axis of the shaft. That is, the motor near 3a of said transmission Ri screw 3, across the spacer 12, the convex spherical surface member 12a having a center of rotation A, by fixing the 12b in screw N _1, swinging of the first spherical bearing 10 It constitutes a spherical surface 10a.

On the base 1 side, the convex spherical members 12a and 12a are sandwiched by a support member 13 fixed to the base 1.
Concave spherical surface member 13a corresponding to 12b, by fixing the 13b screwing N _2, receiving surface of the first spherical bearing 10
1 is configured. The radii of the curved surfaces of the concave spherical members 13a and 13b are slightly larger than the radii of the curved surfaces of the convex spherical members 12a and 12b, so that a gap sufficient to constitute a hydrostatic bearing can be formed.

Reference numeral 14 denotes a spacer, and the spacer 14 is a support member 1
3 and the concave spherical member 13b, and the gap between the convex spherical members 12a and 12b and the concave spherical members 13a and 13b can be adjusted. Here, pockets P for introducing a pressurized fluid (bearing oil) are provided on the inner surfaces of the concave spherical members 13a and 13b to constitute a hydrostatic bearing (a piping system is not shown). ).

Next, the second spherical bearing will be described. Wherein the moving table 2, the said nut 4 screwed to the feed screw 3, is engaged to restrict only to the feed axis J ₀ direction of the feed screw 3, moving table with the movement of the nut 4 2 can move forward and backward. Here, the nut 4 is attached to the moving table 2 with the second spherical bearing 2.
0 enables spherical swing.

That is, the nut 4 is provided with a thrust direction support member (hereinafter simply referred to as a thrust member) 4a having a screw thread to be screwed into a screw portion of the feed screw 3, and a thrust member on both sides of the thrust member 4a. 4a for supporting the feed screw 4a in the radial direction of the feed screw 3 (hereinafter referred to as a radial support member).
4b and 4c). The thrust member 4a and the radial members 4b, 4
The pocket P for introducing a pressurized fluid to form a hydrostatic bearing is provided on each receiving surface where c faces the feed screw 3.

The thrust member 4a includes convex spherical members 5a and 5b having a curved surface center B on the axis of the feed screw 3.
The second spherical bearing 20 is fixed by the screw N ₃ and forms a swinging spherical surface 20 a of the second spherical bearing 20. On the other hand, a concave spherical member 6 facing the convex spherical members 5a and 5b is provided on the moving table 2 side.
a, 6b are fixed by screwing N ₄ , and the second spherical bearing 20
Are formed. The concave spherical members 6a, 6b
The radius of the curved surface is slightly larger than the radius of the curved surfaces of the convex spherical members 5a and 5b, so that a gap sufficient to constitute a hydrostatic bearing can be formed.

Reference numeral 7 denotes a spacer, and the spacer 7 is a movable table 2
And the concave spherical member 6a, and the convex spherical member 5
It is configured such that opposing gaps between the a and 5b and the concave spherical members 6a and 6b can be adjusted. Here, the concave spherical member 6
Pockets P for introducing a pressurized fluid (bearing oil) to form a hydrostatic bearing are also provided on the inner surfaces of a and 6b (the piping system is not shown). Thereby, the nut 4 is
The feed screw 3 is supported by a hydrostatic bearing by a spherical bearing 20 capable of oscillating spherically in an arbitrary direction.

Next, a description will be given of a vitrifying member for preventing the nut 4 from rotating around the axis of the feed screw 3. Figure 2 a cross-sectional view of (b) (including the rotation center B in FIG. 1, the axis J ₀ perpendicular cross-sectional view with respect to) at 30 in Kere member consisting of projecting pieces of rectangular shape, the Kere member 30, The nut 4 is erected on a thrust member 4a which is a main part of the nut 4.

Reference numeral 31 denotes a rotating member .
Last plate 32, face each other with a hydrostatic bearing with respect to the moving table 2, and is configured to be rotatable about the pitch axis J ₁ perpendicular to the feed axis J ₀ through the center of the groove 31a. Further, the Kere member 30, to the groove 31a of the rotary member 31 is pivotably fitted loosely against yaw axis J ₂ perpendicular to the pitch axis J ₁ of the feed screw 3 (Fig. 2 (A)).

The head of the knurling member 30 may be flat if a sufficient gap is provided with respect to the opposing surface of the groove 31a.
Intersection of ₁ and the yaw axis J ₂ may be formed in an arc curved surface centered on the. 33 is a pocket for a hydrostatic bearing . That is, the Kere member 30, with respect to the moving table 2, is restricted only feed axis J ₀ around the motion is engaged. For this reason, when the nut 4 moves with respect to the feed screw 3, only the pitch movement of the feed screw 3 is transmitted to the moving table 2 even if the posture is changed due to bending or misalignment of the feed screw 3. You can do it.

In the above embodiment, when the feed screw 3 is rotated by the motor M, the nut 4 screwed to the feed screw 3
Moves along the feed screw 3 is moved sends the moving table 2 to the direction (axial J ₀ direction). At this time, feed screw 3
Has a two-point support structure pivotally supported by the first and second spherical bearings 10 and 20, so that abnormal swing (yaw,
Even if pitching occurs, it is appropriately absorbed by the two spherical bearings 10 and 20, and only the operation of the feed pitch is transmitted from the feed screw 3 to the moving table 2 via the nut 4.

In the above-described embodiment, an example has been shown in which the threaded portion of the nut 4 and the feed screw 3 and the bearing portions of the first and second spherical bearings 10 and 20 are respectively static pressure bearings. A ball bearing may be used at an appropriate portion of the screw portion and the bearing portion. FIG. 3 shows that the nut and the feed screw are constituted by the ball screw mechanism 101,
This shows an example in which a spherical bearing is constituted by a ball bearing 102.

Similarly, the rotating member holding the vignetting member may be supported by a rolling bearing using a ball bearing.

[0026]

As described above, the present invention provides a moving table which can be moved in one direction with respect to a base, a nut provided on the moving table, and an axial center in a moving direction of the moving table. A feed screw screwed to a nut, wherein the feed screw is rotated to position the moving table at a desired position with respect to the base. For the moving table,
An engagement means for restricting and engaging around the screw axis in the axial direction of the feed screw, and having a rotation center on the axis of the feed screw,
Fixed to the base and at least one of the lead screws
And a second spherical bearing that has a rotation center on the axis of the feed screw, is fixed to the moving table, and supports the nut. In addition, the two spherical bearings can absorb spherical swings (yaw, rolling, pitching) of the screw shaft and the nut due to misalignment of the nut or bending of the feed screw.

For this reason, it is possible to realize an engaging means which has high rigidity in the feed direction and can transmit only the feed pitch operation to the moving table purely. To play. Special
According to the second aspect, in addition to the above-described effects, the moving table is provided.
The movement of the rotating member with respect to the
The adverse effects caused by bending the feed screw, etc.
Can be absorbed between the
Prevent yawing and pitching of the moving table
There is an effect that can be done.

[Brief description of the drawings]

FIG. 1 is a sectional view showing first and second spherical bearings of the device of the present invention.

FIG. 2 (a) is a front view showing a holding portion of a button member;
(B) It is sectional drawing (CC sectional drawing of FIG. 1) which shows the relationship between a button member and a feed screw.

FIG. 3 is a cross-sectional view of an example in which ball bearings are used as first and second spherical bearings.

FIG. 4 is a cross-sectional view of a conventional device in which a thrust bearing is used in an engagement portion between a nut and a moving table, and rotation of the nut is prevented by bellows support.

5A is a principle diagram showing a flange receiving surface attached to a nut, and FIG. 5B is an explanatory diagram showing a pressure distribution on a thrust receiving surface generated by a falling moment of the nut.

[Explanation of symbols]

Reference Signs List 1 base 2 moving table 3 feed screw 4 nut 4a thrust support member 4b radial support member 5a, 5b convex spherical member 6a, 6b concave spherical member 10 first spherical bearing 10a oscillating spherical surface 11 receiving surface 12a, 12b convex spherical surface Member 13 Supporting members 13a, 13b Concave spherical member 20 Second spherical bearing 20a Oscillating spherical surface 21 Receiving surface 30 Rotating member 31 Rotating plate 32 Thrust plate 101 Ball screw mechanism 102 Ball bearing A, B Rotation center of spherical bearing P (static) Pressure bearing) Pocket J ₀ Feed shaft (center axis of feed screw) J ₁ Pitch axis J ₂ Yaw axis

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H 19/00-31/00 B23Q 5/44 B25J 9/02

Claims (5)

(57) [Claims] 1. A moving table guided in one direction relative to a base, a nut provided on the moving table, and having an axis in a moving direction of the moving table and screwed to the nut. A table feeder comprising: a feed screw; and rotating the feed screw to position the moving table at a desired position with respect to the base. Before regulating around the axis
An engagement means for engaging with the moving table ; and a rotation center on an axis of the feed screw, the shift means moving in the axial direction of the feed screw.
A first spherical bearing fixed to the base so as not to move and supporting at least one portion of the feed screw; a first spherical bearing having a rotation center on the axis of the feed screw;
Move with the moving table and the nut
And a second spherical bearing fixed to the movable table and supporting the nut. 2. The moving means is provided on the moving table via a viscous member erected on the nut and a pitch axis orthogonal to a feed axis of the feed screw and via a static pressure bearing. The tip of the button member is loosely fitted to a yaw axis orthogonal to the pitch axis in a groove in the feed axis direction formed in the rotary member. The table feeder according to claim 1, wherein: 3. The table feeder according to claim 1, wherein at least one of the first spherical bearing and the second spherical bearing is a hydrostatic bearing. 4. The table feeder according to claim 1, wherein at least one of the first spherical bearing and the second spherical bearing is a ball bearing. 5. The table feed device according to claim 1, wherein said nut and said feed screw are constituted by a ball screw mechanism.