JP2673849B2 - Linear motion guide device with force detection means - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion guide device which is widely used in, for example, semiconductor manufacturing equipment, machine tools, various inspection devices and the like, and more particularly to a linear motion guide device with force detecting means.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher precision in fine processing as represented by semiconductor technology. Since NC (Numerical Control) was developed, position control has dramatically improved the machining accuracy. In order to make such position control highly accurate, conventionally, efforts have been made to increase the rigidity of the machine tool.

[0003]

However, increasing the rigidity of a machine tool has its limits, and it has become difficult to obtain the machining accuracy required for recent micromachining.

On the other hand, in machining, the force is measured to know the amount of deformation of the machine, the tool, the work, etc., so that not only the machining accuracy of the work but also the change in shape of the tool, abnormality detection, coping with disturbance, It is also necessary to consider that excessive force is not applied to the work or tool, and the machining efficiency is taken into consideration. By monitoring the force, the processing status can be grasped accurately.

Nowadays, with the advance of automation technology, machine tools and machining systems are considerably unmanned and labor-saving, but it is difficult to find a system that actually performs unmanned operation for 24 hours.

The cause thereof is dealt with because there is no effective means for detecting when a condition different from the set condition occurs due to an unexpected tool breakage in actual machining or a change in the surrounding environment. Because you can't. In addition, it is because the skill of skilled workers judges the force applied to the work at the time of processing from the experience and finely adjusts it to safely and precisely process the current machine tool. .

Therefore, it has become necessary to detect a force, which is an important element of machining, which is lacking in conventional position control, and to feed back force information to control a machine tool.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to provide a rolling contact type linear motion widely used for a linear guide portion of a semiconductor manufacturing apparatus, a machine tool or the like. It is an object of the present invention to provide a linear motion guide device with force detection means that can detect force that is actually applied with high accuracy and monitor force information by incorporating force detection means into the guide device.

[0009]

In order to achieve the above object, according to the present invention, a track rail, a large number of rolling elements, and a linear slide along the track rail via the rolling elements. A guide for linear motion, comprising a slide base freely provided, and a table on which a workpiece is mounted is attached to the slide base.
The force detection means that can detect the force acting on the device
Provided on the moving table, the force detecting means elastically changes in the acting direction of the force.
Shapeable elastic member and changes according to the load of the elastic member
Displacement or strain that converts the displacement or strain into an electrical signal
And the detection by the force detection means.
The direction of the force is
The direction perpendicular to the pseudo sliding surface between the slides and the track
Direction orthogonal to the base and parallel to the pseudo sliding surface
Of these, at least one direction is characterized.

Elastic members can be elastically deformed only in the direction of force application.
It is characterized by having a structure that is functional and rigid in other directions .

[0011]

It is preferable that the elastic member has a structure having a thin portion that is elastically deformable in the direction in which the force acts.

Further, it is effective to have a structure in which a strain gauge is attached as a strain detecting means to the thin portion.

A plurality of slides are provided.
I do.

[0015]

In the linear motion guide device with force detecting means having the above structure, the force actually acting on the linear motion guide device can be directly detected. Especially, a guide device for linear motion
The load acting on the specific rolling element can be detected.
For example, to detect the force applied in the length direction of a track rail,
Detects rolling resistance of rolling elements between slide and track rail
Will be. Rolling resistance is proportional to the load acting on the rolling elements
I do. Also, for the pseudo sliding surface between the track rail and the sliding base,
Force applied in the direction orthogonal to
The detection of the force applied at right angles and in the direction parallel to the pseudo sliding surface is
The load itself acting on the rolling element will be detected.

Further, the force can be accurately detected by detecting the displacement or strain of the elastic member which is elastically deformed according to the change of the force.

Further, by providing the elastic member so as to be elastically deformable in the force acting direction and rigid in the direction different from the force acting direction, the required rigidity can be obtained.

Further, the force can be detected with higher sensitivity by adopting a structure in which the strain gauge is attached to the thin portion.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 (a) shows a conceptual configuration of a linear motion guide device with force detecting means of the present invention. This linear motion guide device is composed of a track rail 1 that extends linearly and a slide base 3 that is mounted on the track rail 1 via a number of balls 2 as rolling elements. This sliding base 3 is provided between a mounting portion 4 to which a guided member such as a movable table 7 is mounted, a slide portion 5 having a portion on which the ball 2 rolls, and between the mounting portion 4 and the sliding portion 5. And a force detection means 6 that is provided. Force detection means 6
The detection signal detected by is transmitted to various controller units 100 as force information.

FIG. 1 (b) shows a basic use example of such a linear motion guide device. That is, a pair of track rails 1, 1 are laid parallel to each other, and
A total of four sliding bases 3, 3, one on each side sliding on the top
The movable table 7 is mounted on the surfaces 3 and 3. The work 8 is processed on the movable table 7. Tool 9 during processing
The force acting on the work 8 from the work is transmitted to the slide base 3 of the linear motion guide device through the movable table 7.

The force information detected by the force detecting means 6 is stored by using a computer or the like. By using this force information data and empirical knowledge about machining, the machining state can be modeled, and future machining state prediction,
Prediction becomes possible, and feed-forward control that corrects the current machining state based on the predicted and predicted future machining state becomes possible.

That is, the force acting on the tool 9 is transmitted to the slide base 3 through the movable table 7, and the force detecting means 6 provided on the slide base 3 detects the force actually acting on the tool 9. be able to. By detecting this force, it is possible to detect the shape change and abnormality of the tool 9, recognize the shape of the work 8, and deal with the case where the work 8 or the tool 9 is applied with a force equal to or more than a preset value.

Further, by using the force applied to the work 8 as information, it becomes possible to model the deformation of the work 8 due to the processing force.

The forces acting on the linear motion guide device are a radial load acting vertically on the slide base 3, a thrust load acting in the front-back direction of the slide base 3, and the slide load of the slide base 3. There are three forces of lateral load acting in the left and right lateral directions, and six forces of rotational moments about each of the three directions. For convenience of explanation, as shown in FIG. 1 (c), the slide table 3 slides on the Y axes of the XYZ orthogonal coordinate system which are orthogonal to each other with the track rail 1 below and the slide table 3 above. In the longitudinal direction of the track rail 1, which is the direction of
The Z axis is parallel to the pseudo sliding surface of the track rail 1 and orthogonal to the sliding direction of the slide base 3, and the Z-axis is perpendicular to the pseudo sliding surface of the track rail 1. To explain, the radial load corresponds to the Z-axis load, the thrust load corresponds to the Y-axis load, and the lateral load corresponds to the X-direction load. Further, the moments about the three axes correspond to the moments about the X axis, the Y axis, and the Z axis. Here, the pseudo sliding surface means the left and right balls 2,
It is a virtual plane connecting two. The force detection means 6 has X-axis and Y-axis.
The force detecting means 6 may be configured to detect all the forces in the axial and Z-axis directions, or may be configured to detect only the force in a specific direction. It is a schematic diagram which shows a simple structure. That is, the force detecting means 6
Is provided with an elastic member 11 that is elastically deformable in the axial direction, and a detection means 12 that detects the axial displacement or strain of the elastic member 11 by converting it into an electric signal and detects the elastic member 1.
1 is interposed between the fixed member 13 and the movable member 14 to connect the fixed member 13 and the movable member 14.
Then, the elastic member 11 elastically deforms according to the change in force,
The strain or displacement of the elastic member 11 is converted into an electric signal by the detection means 12 to detect the axial force.

3A to 3E, the force detecting means 10 is shown.
Various modifications of the displacement or strain detection means 12 are shown.

FIG. 3A shows an elastic member 11 using a resistance type sensor 12a such as a strain gauge as a detecting means.
The distortion of is detected.

The one shown in FIG. 3 (b) detects the displacement of the elastic member 11 by using a voltage type sensor 12b which detects the displacement as a voltage change by using a piezoelectric element or an electrostrictive element as the detecting means. It was done.

FIG. 3C shows an electromagnetic induction type sensor 12 such as a differential transformer or an eddy current sensor as a detecting means.
The displacement of the elastic member 11 is detected by using c.

In FIG. 3 (d), an electrostatic capacity type gap sensor 12d is used as a detecting means to detect the displacement of the elastic member 11 by converting it into an electric capacity.

The one shown in FIG. 3 (e) is one in which the displacement of the elastic member 11 is detected by using a light interference type optical fiber sensor 12e as the detecting means.

Other than the illustrated example, various sensors for detecting the displacement of the elastic member 11 can be used. FIG. 4 shows various structural examples of the linear motion guide device when the force detection means 6 of FIG. 2 is applied.

FIG. 4A shows the case where the force detecting means 6 detects the force in the Z-axis direction, that is, the vertical direction.
4B shows a case where the force detection means 6 detects a force in the X-axis direction, that is, the lateral direction, and FIG. 4C shows a case where the force detection means 6 detects a force in the Y-axis direction, that is, the front-back direction. The case is shown.

Of course, not only the force in one direction but also the force in two or three directions can be detected by combining them.

FIG. 4 (d) shows the case of detecting the forces in the two directions of the X-axis and the Z-axis. Although not shown, FIG. 4 (b)
It is possible to detect the forces in the two directions of the XY axes by combining (c), and to detect the forces in the two directions of the YZ axes by combining Fig. 4 (a) and (c). 4 (a)-(c)
If combined with each other, it is possible to adopt a configuration in which forces in three directions of the X, Y, Z axes are detected.

FIG. 5 shows a linear motion guide device in which the model configuration shown in FIG. 4 (a) is further embodied.
This linear motion guide device detects only the force in the Z-axis direction, and basically has the same configuration as the device shown in FIG. 4, and uses a thin leaf spring as the elastic member 11A of the force detection means 6, The structure is integrated with the slide portion 5 and the attachment portion 4.

That is, the mounting portion 4 is an annular member, and the elastic member 11A of the force detecting means 6 has a thin annular flat plate shape, and the outer end of the annular flat plate elastic member 11A is fixed to the inner end of the mounting portion 4. The inner end of the elastic member 11A is fixed to the slide portion 5 so as to be elastically deformable in the Z-axis direction.

In this example, the mounting portion 4, the elastic member 11A, and the slide portion 5 are integrally formed by processing a rectangular block body that constitutes the slide base 3. That is, slits 15 are formed on the front, rear, left, and right side surfaces of the slide base 3 all around.
On the other hand, a circular concave portion 16 having a diameter larger than the diameter of the rear end of the slit 15 is formed in the center of the upper surface of the sliding base 3, and the elastic member 11 is made thin between the bottom surface of the concave portion 16 and the slit 15.
A. The opening of the recess 16 of the slide base 3 is closed by a lid 17.

By forming the elastic member 11A into an annular flat plate structure, the elastic member 11A is elastically deformable in the Z-axis direction and is rigid in the X- and Y-axis directions other than the Z-axis. , The rigidity in the Y-axis direction can be kept high.

A strain gauge 12a is attached to the surface of the elastic member 11A as a detecting means for detecting the amount of displacement corresponding to the elastic deformation of the elastic member 11A. The strain gauge 12a is attached to the base of the elastic member 11A having the largest strain to increase the sensitivity.

In the illustrated example, four strain gauges 12a are equally distributed on the outer diameter end of the annular elastic member 11A, while four strain gauges 12a are displaced on the inner diameter end by 45 degrees from the outer diameter end. A total of eight strain gauges 12a are used.

Further, in this embodiment, the strain gauge 12a is used.
Is attached to the surface of the elastic member 11A on the concave portion 16 side, and the signal line from the strain gauge 12a is taken out through the connection terminal 18 fixed to the attaching portion 4. The detection signal from the strain gauge 12a is amplified by the strain amplifier 101, further converted into a digital signal by the A / D converter 102, and processed and judged by the controller 103 as force information.

In this embodiment, since the elastic member 11A has an annular shape, it can be tilted in all directions with uniform spring characteristics. Therefore, each strain gauge 12a
Since each part of the elastic member 11A is elastically deformed in proportion to the load at each position where is attached, by reading the output information from each strain gauge 12a, the Z-axis direction that acts on the upper surface of the slide base 3 is read. You can see the distribution of the force in the circumferential direction. By knowing the distribution of the force in the Z-axis direction in the circumferential direction, it is possible to accurately detect not only the magnitude of the force but also its directionality and the like.

FIG. 6 shows various shapes of the elastic member 11A. In addition to the simple annular flat plate structure shown in FIG. 6 (a), a hole 11B is formed as shown in FIGS. 6 (b) to 6 (e). It can also be formed into an open shape.

In FIG. 7, the elastic member 11B interposed between the mounting portion 4 and the slider portion 5 has a cylindrical shape so that forces in the XYZ axis directions can be detected.

That is, as in FIG. 6, the mounting portion 4 is an annular member, and the annular elastic member 11 is attached to the annular mounting portion 4.
The upper end of B is fixed, and the lower end of the elastic member 11B is fixed to the slider portion 5.

In the case of this cylindrical elastic member 11B, if the strain gauge 12a is attached to a part of the elastic member 11B in the vertical direction as shown in FIG. 7 (a), it is mainly effective for detecting the force in the Z-axis direction. , The elastic member 11B as shown in FIG. 7 (c).
It is effective to detect the force in the XY axis directions if it is attached to the base part of the. Further, even if the shear gauge is attached to the surface of the elastic member 11B, it is effective for detecting the force in the XY axis directions.

In each of the above embodiments, the force detecting means 6 has an integral structure with the mounting portion 4 and the slider portion 5, but the force detecting means 6 may have a separate structure as shown in FIG. .

In this embodiment, the force detecting means 6 and the slide portion 5 are divided and the force detecting means 6 and the mounting portion 4 are integrally formed. That is, the force detecting means 6 includes a fixing portion 61 fixed to the slide portion 5 with bolts 51, a mounting portion 4 for mounting a non-guide member, and the fixing portion 6.
1A and the elastic member 11A integrally connecting the mounting portion 4,
It is composed of a strain gauge 12a as a displacement detecting means attached to the surface of the elastic member 11A. The elastic member 11A has an annular flat plate structure similar to that shown in FIG. 5, is elastically deformable in the Z-axis direction, and has a rigid structure in the X-axis and Y-axis directions.

With such a separate structure, it is possible to prepare a plurality of types of force detecting means 6 and replace only the force detecting means 6 as an attachment according to the type of force to be detected.

FIGS. 8B and 8C show various modifications of the replaceable force detecting means. That is, FIG. 8B shows a parallel plate structure in which two elastic members having an annular plate structure are provided in parallel. By doing so, it is possible to selectively detect only in the Z-axis direction. .

Further, FIG. 8 (c) shows a structure in which an elastic member 11C having a parallel plate structure elastically deformable only in the X-axis direction and an elastic member 11D having a parallel plate structure elastically deformable only in the Y-axis direction are combined. is there. By doing so, it is possible to detect the force in the XY axis directions and the moment about the Z axis.

[0053]

According to the present invention having the above-mentioned structure and operation, it is possible to directly detect the force actually applied to the linear motion guide device. Especially in the longitudinal direction of the track rail
This force, against the pseudo sliding surface between the track rail and the slide
Force applied in the orthogonal direction, only orthogonal to the track rail
At least one of the forces applied in the direction parallel to the pseudo sliding surface
If the force in the direction is detected, the guide device for linear motion
The load acting on the specific rolling element can be detected.

Further, the force can be detected with high accuracy by detecting the displacement or strain of the elastic member which is elastically deformed according to the change of the force.

Further, by forming the elastic member into a rigid shape in a direction other than the force acting direction, it is possible to prevent an unnecessary reduction in rigidity of the linear motion guide device.

[Brief description of the drawings]

FIG. 1 (a) is a diagram showing a conceptual configuration of a linear motion guide device with force detecting means of the present invention, and FIG. 1 (b) is a schematic perspective view showing a usage example of the linear motion guide device. FIG. (C) is a perspective view for explaining a load acting direction of the linear motion guide device.

FIG. 2 is a configuration diagram schematically showing force detection means.

3 (a) to 3 (e) are configuration diagrams showing various modifications of the force detecting means of FIG.

4 (a) to 4 (d) are schematic views showing various structural examples of the linear motion guide device with force detecting means of the present invention expressed by using the force detecting means of the basic configuration of FIG. .

FIG. 5 shows a first specific example of the present invention and is shown in FIG.
Is a longitudinal sectional view, (b) is a plan view, and (c) and (d) are sectional views in the vicinity of the elastic member for explaining the operating state.

6 (a) to 6 (e) are plan views showing various modifications of the elastic member of the apparatus shown in FIG.

7A and 7B show a second specific example of the present invention. FIG. 7A is a vertical sectional view, FIG. 7B is a plan view, and FIG. 7C is XY.
It is a principal part sectional view which shows the attachment position of the strain gauge effective for the force detection of an axial direction.

FIG. 8 (a) is a schematic cross-sectional view of a linear motion guide device in which a force detecting means according to a third embodiment of the present invention is a split type;
6B and 6C are schematic cross-sectional views showing various modifications of the split type force detecting means shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Track rail 2 Ball (rolling element) 3 Sliding table 4 Mounting part 5 Sliding part 6 Recessed part 7 Movable table (guided member) 11, 11A, 11B Elastic member 12, 12a, 12b, 12c, 12d, 12e Displacement detection means 13 Fixed member 14 Movable member

Claims (5)

(57) [Claims] 1. A track rail, a large number of rolling elements, and a slide base slidably provided in a linear direction along the track rail via the rolling elements, wherein a work is mounted on the slide base. In the linear motion guide device to which the table to be mounted is attached, the slide base is provided with force detection means capable of detecting a force acting on the linear motion guide device from the table side, and the force detection means is An elastic member that is elastically deformable in the direction of force application, and a displacement or strain detection that converts a displacement or strain that changes according to the load of the elastic member into an electrical signal are provided. The direction of the force to be detected is the length direction of the track rail, the direction orthogonal to the pseudo sliding surface between the track rail and the slide, the direction orthogonal to the track rail and parallel to the pseudo sliding surface. In at least one of the three directions Linear motion guide apparatus according to claim Rukoto. 2. The linear motion guide device with force detecting means according to claim 1, wherein the elastic member is elastically deformable only in the force acting direction and is rigid in other directions. 3. The linear motion guide device with force detecting means according to claim 1, wherein the elastic member has a thin portion that is elastically deformable in the direction in which the force acts. 4. The linear motion guide device with force detecting means according to claim 3, wherein a strain gauge is attached to the thin portion as strain detecting means. 5. A plurality of sliding bases are provided.
The guide device for linear movement with force detection means according to any one of 2, 3, and 4.