JP2511356B2 - Mobile platform force detection system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving table apparatus used for, for example, a machine tool, and more particularly to a force detecting system for detecting a force acting on a guided member provided on the moving table.

[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 in order to solve the above-mentioned problems of the prior art, and an object thereof is to apply only the force in the Z-axis direction acting on each moving element of a moving table device such as a machine tool. It is an object of the present invention to provide a force detection system for a movable table device capable of highly accurately detecting forces in three directions actually applied to a machine tool or the like and monitoring force information only by detecting the force.

[0009]

In order to achieve the above object, in the present invention, a pair of track rails extending in parallel to each other and a plurality of slidably mounted on the track rails via rolling elements. A moving table and a moving table mounted on the moving table, wherein the plurality of moving elements bear the force acting on the guided member provided on the moving table. the direction perpendicular to the plane created by the rail when the Z-axis direction of the X-Y-Z orthogonal coordinate system, the Z-axis direction force information said that acting on the moving element, the force action of the guided member and position information indicating a relative positional relationship between the points and the moving child, based on the previous
Find the moment about the X-axis or Y-axis of the guided member
The moment from the moving table to the point of force application in the Z-axis direction.
X acting on the guided member by dividing by the height of
It is characterized in that the force in at least one of the axial and Y-axis directions is obtained.

The position information may be information obtained by observing from outside, or may be predetermined program information.

[0011]

In the force detecting system for the moving table apparatus having the above-mentioned structure, the force information in the Z-axis direction acting on each moving element and the guided portion are provided.
From the position information of the force application point of the material in the XY axis direction, the X
The moment acting around the axis and the Y axis can be calculated.
On the other hand, the height in the Z-axis direction from each mover to the point of force application is
Since it is known as placement information, the mode around each X and Y axis
If the element is divided by the height, the X and Y axes that act on the guided member
The force in the direction can be calculated. The forces in the X and Y axis directions are
It is also possible to obtain only the force in the X-axis or Y-axis direction.
However, it is also possible to obtain both axial and Y-axis forces. Ma
Also, the force in the Z-axis direction acting on the guided member is applied to each moving element.
Naturally, it can be obtained by adding the information on the forces acting in the Z-axis direction.
Therefore, the force of the X- and Y-axis directions can be
If is calculated, the XYZ axis direction acting on the guided member
All forces can be obtained only from the force information in the Z-axis direction.
It

[0012]

[0013]

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

FIG. 1 (a) shows the basic structure of a moving table apparatus according to an embodiment of the present invention. That is, a pair of track rails 1, 1 are laid parallel to each other, and
A total of four moving elements 3, 3, one pair on the left and one on the right.
The moving base 7 is attached on the surfaces 3 and 3. A work 8 as a guided member is mounted on the moving table 7. The force F that acts on the work 8 from the tool 9 during processing is transmitted to the mover 3 through the moving table 7.

FIG. 1 (b) shows the track rail 1 and the mover 3 described above.
Shows a conceptual configuration of. That is, the mover 3 is
It is slidably mounted on the track rail 1 through a large number of balls 2 as rolling elements. The moving element 3 includes an attaching portion 4 to which the moving base 7 is attached, a slide portion 5 having a portion on which the ball 2 rolls, and a force detecting means 6 provided between the attaching portion 4 and the slide portion 5. Composed. The detection signal detected by the force detecting means 6 is sent as force information to the controller section 100 as the calculating means.

As shown in FIG. 1 (c), the force applied from the tool 9 to the movable table 7 via the work 8 is XY in the direction orthogonal to the plane created by the pair of track rails 1, 1. -In the Z-axis direction of the Z orthogonal coordinate system, the track rail 1,
When the longitudinal direction of 1 is taken in the Y-axis direction, the radial load FZ acting in the Z-axis direction, the thrust load FY acting in the Y-axis direction, and the lateral load FX acting in the X-axis direction are divided into three directions. have power.

The force detecting means 6 provided on each moving element 3 detects only the force f acting on each moving element 3 in the Z-axis direction.

Then, as shown in FIG. 1C, the force information in the Z-axis direction detected by the force detecting means 6 and the work 8 are detected.
Based on the contact position of the tool 9 that is the force acting point of the tool and the position information that indicates the relative positional relationship between the movable elements 3, the controller unit 100 causes the tool 9 to move the work 8 as a guided member. Force of force acting on X, Y, Z axis direction FX
, FY, FZ are calculated.

The position information may be information obtained by observing from outside, or may be predetermined program information. That is, in the case of NC machine tools, basic data such as tool shape,
Information on the position of the moving table or the work is previously input as NC information, and the force action point on the work at a certain time can be easily known based on this information. As for the position of the moving table, the actual position may be detected by using a CCD element, ultrasonic waves, or the like.

Next, the actual calculation will be specifically described.

First, the force in the Z-axis direction is obtained by adding the forces acting on the moving elements 3.

That is, if the forces acting on the four movers 3 are f1, f2, f3, and f4, the component force FZ of the force acting on the work 8 in the Z-axis direction is FZ = f1 + f2 + f3 + f4.

Further, the force acting point O of the work 8 is set in the Z-axis direction.
The point projected on the upper surface of the moving table 7 is set to zero in the XYZ orthogonal coordinate system.
Z axis direction from the upper surface of the movable table 7 to the point of force application O
The height of the direction is h, and the X and Y coordinates of the four movers 3 are X1 and X.
2; Y1 and Y2, and the moments acting around the X axis and the Y axis are MX and MY, the forces FX and FY in the X and Y axis directions of the forces acting on the work 8 are obtained by the following equations.

That is, FX = MY / h = {X1 (f1 + f2) + X2 (f3 + f4)} / h FY = MX / h = {Y1 (f1 + f2) + Y2 (f3 + f4)} / h.

In short, it is possible to detect the three-direction component forces Fx, FY, FZ of the force F acting on the work 8 by the combination of the four unidirectional force detecting means and the combination of the shape / position information .

On the other hand, the height h of the force acting point O from the moving table 7
Therefore, by dividing the moment around each X and Y axis by the height, the force in the X and Y axis directions can be calculated.

By utilizing the force information data and empirical knowledge about machining, the machining state can be modeled, and the future machining state can be predicted and predicted.
It becomes possible to perform feedforward control in which the current machining state is corrected based on the predicted future machining state.

That is, the force acting on the tool 9 is the moving table 7
The force that is transmitted to the moving element 3 through the force detecting means 6 provided on the moving element 3 can detect the force that actually acts on the tool 9. By detecting this force, the shape change of the tool 9 and the abnormality detection, the shape recognition of the work 8, and the force more than a preset value can be applied to the work 8 and the tool 9.
It is possible to deal with when

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.

FIG. 2 is a schematic diagram showing the basic structure of the force detecting means 6. That is, the force detecting means 6 includes an elastic member 11 which is elastically deformable in the axial direction, and the elastic member 11.
Detecting means 12 for detecting the axial displacement or strain of the fixed member 13 by converting it into an electric signal, and the elastic member 11 is interposed between the fixed member 13 and the movable member 14, and the fixed member 13 is provided.
And the movable member 14 are connected to each other. And
The elastic member 11 is elastically deformed according to the change in force, and 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 modified examples of the detection means 12 are shown.

The one shown in FIG. 3 (a) uses a resistance type sensor 12a such as a strain gauge as a detecting means and uses an elastic member 11a.
The distortion of is detected.

The one shown in FIG. 3 (b) detects the displacement of the elastic member 11 by using the 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.

The one shown in FIG. 3 (c) is 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), a capacitance 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 capacitance.

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 type sensor 12e as the detecting means.

Besides this, various sensors for detecting the displacement of the elastic member 11 can be used without being limited to the illustrated example. FIG. 4 shows a conceptual configuration when the detecting means of FIG. 2 is applied to a mover.

FIG. 5 shows a more specific structural example of the conceptual structure of FIG. 4, in which the elastic member 11A of the force detecting means 6 is used.
A thin leaf spring is used as the slider, and the slider portion 5 and the mounting portion 4 are integrated with each other.

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-shaped 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 slider 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 slider portion 5 are integrally formed by processing a rectangular block body forming 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 rigid in the X- and Y-axis directions other than the Z-axis. , The rigidity in the Y-axis direction can be kept high.

On the surface of the elastic member 11A, a strain gauge 12a is attached 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 arranged at the outer diameter end portion of the annular elastic member 11A, while four strain gauges are arranged at the inner diameter end portion with a phase difference of 45 degrees from the outer diameter end side. A total of eight strain gauges 12a are used.

Further, in this embodiment, the strain gauge 12a
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 17 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 100 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
Each portion of the elastic member 11A elastically deforms in proportion to the load at each position where is attached. As a result, by reading the output information from each strain gauge 12a, the distribution of the force in the Z-axis direction acting on the upper surface of the slide base 3 in the circumferential direction can be known. 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, action position, and the like. In addition, the moment around the X-axis and the Y-axis can be detected from the distribution of the Z-axis direction force and the distance between the attachment positions of the strain gauges.

FIG. 6 shows various shapes of the elastic member 11A. In addition to a simple annular flat plate structure as shown in FIG. 6 (a), a hole 11B is provided as shown in FIGS. 6 (b)-(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 thin cylindrical shape. Even with such a configuration, the force in the Z-axis direction can be detected. When detecting the force in the Z-axis direction, it is preferable to attach the strain gauge 12a to the axially intermediate portion of the elastic member 11B.

However, in the case of this cylindrical elastic member 11B, it is possible to detect not only the force in the Z-axis direction but also the force in the XY-axis direction.

[0049]

The present invention has the above-mentioned configuration and action, and provides force information in the Z-axis direction acting on each moving element and a work force.
The relative position between the force acting point of the guided member such as
Guided member by the combination of position information showing the positional relationship
Detecting the forces acting on the X and Y axes
Can be.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a conceptual configuration of a force detection system for a moving table apparatus according to the present invention, FIG. 1 (b) is a schematic oblique configuration diagram of a sliding table, and FIG. It is a figure which shows the calculation procedure of a system.

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

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

FIG. 4 is a schematic view 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 more specific example of a sliding table having force detecting means, in which FIG. 5 (a) is a longitudinal sectional view, FIG. 5 (b) is a plan view, and FIG.
(c) And (d) is a sectional view of the elastic member vicinity for explaining an operating state.

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

7 (a) and 7 (b) show another specific example of the slide base having force detecting means. FIG. 7 (a) is a vertical sectional view and FIG.
(b) is a plan view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Track rail 2 Ball (rolling element) 3 Moving element 4 Mounting part 5 Slider part 6 Recessed part 7 Moving stand 8 Work piece (guided member) 9 Tool 11, 11A, 11B Elastic member 12, 12a, 12b, 12c, 12d, 12e Displacement detecting means 13 Fixed member 14 Movable member

Claims (3)

(57) [Claims] 1. A pair of track rails extending in parallel with each other, a plurality of moving elements slidably mounted on the track rails via rolling elements, and a moving table mounted on the moving element, In a moving table device in which the plurality of moving elements bear a force acting on a guided member provided on the moving table, a direction orthogonal to a plane created by the pair of track rails is an XYZ orthogonal coordinate system. when the Z-axis direction, and the position information representing the the Z-axis direction of the force information that acting on the moving element, the relative positional relationship between the force application point of the guide member each mobile child, Based on the X-axis of the guided member
Or, calculate the moment around the Y-axis and transfer the moment.
By dividing by the height in the Z-axis direction from the platform to the point of force application
In addition, a force detection system for a movable table device is characterized in that a force in at least one of the X-axis and Y-axis directions acting on the guided member is obtained. 2. The force detection system for a mobile platform according to claim 1, wherein the position information is information obtained by observing from outside. 3. The force detection system for a mobile table device according to claim 1, wherein the position information is predetermined program information.