JP2001004360A - Metering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce measurement errors by coupling a slider to a carrier in such a way that dynamic vectors do not occur except a vector directed in the travelling direction of the slider, preventing return errors, and improving repeat accuracy. SOLUTION: A first bearing part 15 with a spherical end part 15a opposite to a slider 7 is provided for a carrier 8, and a second bearing part 16 with an approximately conical recessed part 16a to receive the spherical surface 15a of the first bearing part 15 is arranged in the slider 7. The carrier 8 and slider 7 are fastened to the slider 7 at one point in a straight line which intersects the center of the spherical surface 15a and is in parallel with the traveling direction of the slider 7, and the spherical surface 15a is pressed against and coupled to the recessed part 16a by a coil spring 18 to provide the carrier 8 with a biasing force in the direction in prattle with the travelling direction of the slider 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a machine body such as a machine tool, an industrial machine, a precision measuring instrument or the like having a movable portion which moves relatively linearly, and a relative movement distance and a relative movement of the movable portion. The present invention relates to a measuring device used for measuring a position or the like.

[0002]

2. Description of the Related Art A measuring instrument is attached to opposed movable parts which move relatively linearly in a machine tool, an industrial machine, a precision measuring instrument or the like (hereinafter simply referred to as a machine main body). It is used to measure the relative movement position, relative movement distance, etc.

In the conventional measuring device, a long scale provided with a scale for position detection at the time of linear movement in the movable section is attached to one of the movable sections, and the scale provided on this scale is attached to the scale. A detection unit provided with a detection head for reading is attached to the other of the movable parts. The detection unit is arranged on a scale, and a slider for reading a scale displacement by a detection head, and a carrier connected to the slider and moving together with the other movable portion of the machine main body are connected via a connection portion. It becomes.

In the measuring device having the above-described configuration, when the carrier moves in accordance with the linear movement of the movable portion of the machine main body,
The slider is pulled or pushed through the connection with the carrier and travels on the scale along its longitudinal direction. The measuring device reads the displacement of the scale with the detection head provided on the slider, and measures the relative movement position and the relative movement distance by running the slider as described above.

[0005]

In the conventional measuring device, the carrier moves with the linear movement of the movable part of the machine body attached as described above, and the movement follows the meandering and undulation of the machine body. I do. Further, in the measuring device, a slider is provided in contact with the scale, and travels following the flatness of the scale, specifically, following the meandering or undulation. That is, in the measuring device, the relative movement position and the relative movement distance are measured by the slider and the carrier constrained by different movements, and the position of the slider and the carrier may be shifted with the movement at the time of the measurement. is there. This displacement between the slider and the carrier is transmitted to the slider via the connecting portion.

In the conventional measuring device, since the slider and the carrier are connected by applying a force to the slider or the carrier irrespective of the contact point at the connecting portion between the slider and the carrier, the displacement as described above is caused. As a result, a mechanical vector is generated in a direction other than the traveling direction of the slider, in other words, in a direction that hinders the linear movement of the slider, and there is a problem that a return error or a measurement error due to a decrease in repetition accuracy occurs.

[0007] In a measuring instrument, especially when high performance and high resolution are achieved, a contact friction force due to a mechanical vector generated at a connecting portion between a slider and a carrier becomes a force inhibiting movement, resulting in a reduction in repetition accuracy and return error. Affect.

Therefore, the present invention connects the slider and the carrier so as not to generate a mechanical vector heading in a direction other than the running direction of the slider, thereby preventing a return error and improving the repetition accuracy, thereby reducing the measurement error. It is an object of the present invention to provide a measuring device that performs measurement.

[0009]

A measuring device according to the present invention for achieving the above object has a flat and long scale on which scales for position detection are provided along the longitudinal direction, and a scale on the scale. A slider provided with a detection head that runs and reads a scale to obtain a position detection signal; and a carrier that is connected to the slider and moves the slider along the longitudinal direction of the scale. A first bearing portion is formed on the carrier, the first bearing portion protruding to the side and having a spherical end at the end facing the slider, and is provided in the carrier, and has a substantially conical shape facing the first bearing and receiving the spherical surface of the first bearing. A second bearing having a concave portion is disposed on the slider. The carrier and the slider are locked to the slider at one point on a straight line parallel to the running direction of the slider passing through the center of the spherical surface or at a plurality of points located symmetrically with respect to the straight line. It is characterized in that the spherical surface of the first bearing portion is pressed against and connected to the concave portion of the second bearing portion by an elastic member that applies a biasing force in a parallel direction to the carrier.

According to the measuring device of the present invention having the above structure, the slider and the carrier are connected to each other by the first bearing having a spherical surface and the second bearing having a concave portion for receiving the spherical surface. The center of the spherical surface rotating in the recess and the point at which the urging force is applied to the carrier from the slider or the midpoint between the plurality of points at which the urging force is applied are aligned on a straight line parallel to the running direction of the slider. By positioning the slider and applying a pulling force in parallel with the running direction of the slider, the displacement between the slider and the carrier due to the meandering or undulating movement of the scale or the machine body is absorbed, and the mechanical vector heading in a direction other than the running direction of the slider. To prevent the occurrence of a return error and a decrease in repetition accuracy, and to reduce a measurement error in measuring a relative movement position and a relative movement distance.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the measuring device according to the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the measuring apparatus 1 according to the present embodiment is configured as a part of an industrial machine, a machine tool, or the like (hereinafter, referred to as a machine main body 50) and relatively linearly moves. It measures the relative movement position and relative movement distance of the movable parts 50a and 50b, and includes a casing 2 having a substantially rectangular cylindrical shape, and a detection unit 3. In the measuring device 1, the above-described housing 2 is attached to one movable portion 50 a of the machine main body 50, and a driving unit of the detection unit 3, and a carrier described in detail later is attached to the other movable portion 50 b.

The casing 2 accommodates therein a scale 4 having a flat and long shape, so that the longitudinal direction of the scale 4 coincides with the longitudinal direction of the casing 2. The casing 2 has one side surface, specifically, a side surface facing the detection unit 3 disposed, cut out in a longitudinal direction thereof to have a slit 5.
Are formed. In the measuring device 1, the slit 5
As described later, an arm that forms a connecting portion that connects a slider serving as a detecting unit of the detecting unit 3 and a carrier serving as a driving unit enters the inside of the housing 2.

The scale 4 is solidified at a predetermined position in the housing 2 with its both ends supported by a pair of brackets 6 disposed at both ends in the longitudinal direction of the housing 2. Scale 4
As shown in FIG. 2, a scale 4b for position detection is provided on one principal surface (hereinafter, referred to as a scale surface) 4a. The scale 4b is a position signal continuously recorded at predetermined intervals along the longitudinal direction of the scale 4, and may be formed, for example, in a form in which pits or marks are formed at predetermined intervals or a grating on the scale surface 4a. And a magnetic signal whose polarity is inverted at a predetermined recording wavelength is magnetized, although the scale does not appear in appearance. The scale 4 is formed by changing the material according to the type of a detection head that reads a scale 4b and detects a position signal as described later. For example, when an optical detection head is used as the detection head, a glass material such as glass, When a magnetic head is used as a detection head, it is formed of a metal material.

As shown in FIG. 2, the detecting unit 3 includes a slider 7 serving as a detecting section for reading a displacement of a scale 4b provided on a scale surface 4a and detecting a position signal, and a slider 7 connected to the slider 7 and connected to the slider 7. And a carrier 8 serving as a drive unit for running the vehicle 7 by pulling or pushing it.

The slider 7 is disposed on the scale 4, that is, inside the housing 2, and has a scale surface 4 a of the scale 4.
It runs on its top along its length. The slider 7 has
When traveling on the scale 4, a detection head 9 for reading the displacement of the scale 4b provided on the scale surface 4a and detecting the displacement of the scale 4b as a position signal is disposed at a position facing the scale 4b. You. As the detection head 9, a magnetic head, an optical detection head, or the like is used according to the material of the scale 4 and the form of the scale 4b.

The slider 7 is pressed in the direction of the inner wall 2a of the case 2 perpendicular to the scale 4 by an elastic member, for example, a pressing spring 10 shown in FIG. The slider 7 is pressed in the direction of the scale surface 4a of the scale 4 by an elastic member, for example, a pressing spring, although not shown in detail, similarly to the pressing in the direction of the inner wall 2a described above. Further, the slider 7
Is in contact with the above-described inner wall 2a of the housing 2 and the scale surface 4a of the scale 4 via a plurality of rolling bearings 11. The slider 7 is pressed by the elastic member against the inner wall 2a of the housing 2 and the scale surface 4a of the scale 4 as described above, and the rolling bearing 11 is pressed against the pressed portion.
, The flatness of the scale surface 4a,
Specifically, it is configured to smoothly run following the undulation and meandering. In the measuring device 1, although not shown in detail, the rolling bearing 11 is attached to the inner wall 2a in order to reduce abrasion when the slider 7 travels and to secure the flatness of the inner wall 2a with which the rolling bearing 11 contacts. A guide bar made of steel may be embedded in the contacting position, and the rolling bearing 11 may move on the guide bar.

The carrier 8 is provided outside the housing 2 and attached to the other movable portion 50b of the machine body 50 along the longitudinal direction of the housing 2 and the scale 4. The carrier 8 is connected to a signal cable 12 for supplying a position signal detected by the detection head 9 of the slider 7 by reading the scale 4 b to a control device (not shown).

The carrier 8 is, as described above, a main body 5 of the machine.
0, and moves linearly along the longitudinal direction of the housing 2 together with the movable portion 50b constituting the machine main body 50. That is, the carrier 8 has a structure in which the carrier 8 moves following the meandering or undulation of the machine main body 50 having the movable portion 50b.

In the detection unit 3, the slider 7 having the above-described structure and the carrier 8 are connected by a connecting portion 13, and the carrier 8 is connected via the connecting portion 13.
Pulls or pushes the slider 7 to cause the slider 7 to travel. The connecting portion 13 is provided on the carrier 8 and is an arm 1 that enters the inside of the housing 2 through the slit 5 of the housing 2.
4, a first bearing member 15 protruding from the arm 14, and a second bearing member 16 provided on the slider 7 side and opposed to the first bearing member 15. .

The first bearing portion 15 is a spherical bearing formed so as to protrude from the arm 14 toward the slider 7 along the running direction of the slider 7 and has a spherical surface 15a at the tip of the slider 7 side. The first bearing 15 has a spherical surface 15.
a first through-hole 15b is formed which opens to a and reaches a position corresponding to the center of a sphere having a spherical surface 15a as a part of its outer peripheral surface (hereinafter simply referred to as the center of the spherical surface 15a). ing.

The second bearing 16 is an automatic alignment bearing provided on the slider 7 side and provided with a substantially conical concave portion 16a for receiving the spherical surface 15a of the first bearing 15 described above. The second bearing portion 16 has a second spring through hole 16b, which penetrates from the slider 7 side to the bottom surface of the concave portion 16a, and through which a coil spring, which will be described in detail later, is inserted substantially in the center.

The detection unit 3 is configured such that the spherical surface 15a of the first bearing portion 15 provided on the carrier 8 side is pulled and urged toward the slider 7, and the concave portion 16a of the second bearing portion 16 provided on the slider 7 is provided. , The first bearing portion 15 and the second bearing portion 16 are connected as a connecting portion 13. The connecting portion 13 has one end locked by a locking pin 17 provided on the slider 7 and the other end connected to the second spring through hole 16.
b and the first spring through hole 15b and the spherical surface 15a
A tension urging force is applied to the first bearing portion 15 toward the slider 7 by the coil spring 18 locked at a position corresponding to the center of the first bearing. The connecting portion 13 is configured such that the above-described coil spring 18 pulls the spherical surface 15 a, specifically, the direction in which the carrier 8 is pulled toward the slider 7, is parallel to the arrow A direction shown in FIG. And the carrier 8 are connected. In other words, the measuring device 1
Locking pin 17 for locking coil spring 18 on slider 7 side
Is provided on a straight line that passes through the center of the spherical surface 15 a that locks the other end of the coil spring 18 and is parallel to the running direction of the slider 7, and a tension urging force is applied to the carrier 8 from the locking pin 17. ing.

In the measuring device 1, the slider 7 and the carrier 8 are connected by the connecting portion 13 having the above-described configuration, and the slider 7 is connected by the carrier 8 via the connecting portion 13.
The scale 4 is driven by towing or pushing the
Alternatively, even when the position of the slider 7 and the position of the carrier 8 that move together under different constraints from the machine body 50 are displaced, a dynamic vector is generated in a direction that hinders the travel of the slider 7 in the direction of arrow A. do not do. That is,
For example, as shown in FIG. 4, even when the position of the carrier 8 attached to the movable portion 50b is displaced due to a displacement on the machine body 50 side as shown in FIG. The spherical surface 15a rotates about the center thereof as a rotation center, slides in the concave portion 16a, and absorbs the displacement without displacing the center position of the spherical surface 15a. Therefore, the measuring device 1
The position of the coil spring 18 for applying the tension urging force from the slider 7 to the carrier 8 remains unchanged, and the direction of the tension urging force applied to the carrier 8 is changed to the slider 7.
Is maintained in parallel with the traveling direction of the slider 7, and a mechanical vector directed in a direction other than the traveling direction of the slider 7 is not generated by the displacement of the carrier 8.

As described above, in the measuring apparatus 1, the slider-side engagement of the coil spring 18 for applying a tensile force to the carrier 8 and the rotation center of the spherical surface 15a of the first bearing member 15 for absorbing the displacement. The point is positioned on a straight line parallel to the running direction of the slider 7 and the direction of the tension urging force for connecting the slider 7 and the carrier 8 is maintained parallel to the running direction of the slider 7. No dynamic vector other than the traveling direction is generated, so that a return error, which is one of the important performances, is prevented, and the measurement error in the measurement of the relative movement position and the relative movement distance is reduced.

In the present embodiment, the measuring apparatus 1 has been described as having the above-described configuration. However, it is needless to say that the present invention is not limited to this. For example, the second bearing section having the shape shown in FIG. 20 may be used to connect the slider 7 and the carrier 8. The second connecting portion 20 connects the slider 7 and the carrier 8 by receiving the spherical surface 15a of the first connecting portion 15 with the substantially conical concave portion 20a similarly to the second connecting portion 16 described above. The connection at a position closer to the slider 7 is enabled.

Further, as in a measuring device 30 shown in FIG. 6, the position at which the tension applying force is applied from the slider 7 to the carrier 8 is changed, and the coil spring 18 is disposed at a position different from the connecting portion 13. You may. In the measuring device 30, both ends of the coil spring 18 are respectively locked by the slider 7 and the locking rod 31 of the carrier 8 which is provided to protrude from the notch 7 a provided in the slider 7, A tensile urging force is applied to the carrier 8 from the slider 7. In the measuring device 30 as well, the point that the coil spring 18 is locked on the slider 7 side and the carrier 8 is pulled,
The center of the spherical surface 15 a of the first bearing portion 15 is disposed on a straight line parallel to the traveling direction of the slider 7.

Further, as in a measuring device 40 shown in FIG.
A rod-shaped locking bar 4 is attached to the first bearing 15 and the slider 7.
1a and 41b are provided, respectively,
The sliders 7 and 41b may be connected by two coil springs 18, so that the slider 7 is connected to the carrier 8 by applying a tensile biasing force. In such a case, in the measuring device 40, the midpoint x between the two points on the slider 7 that pulls the carrier 8 is a straight line parallel to the running direction of the slider 7 passing through the center of the spherical surface 15 a of the first bearing 15. Two coil springs 18 are provided so as to be located above.

Furthermore, in each of the above-described embodiments, the tension biasing force is applied to the carrier 8 using the coil spring 18, but the present invention is not limited to this.
Instead of the coil spring 18, another elastic member, for example, rubber or the like may be used to apply a tensile urging force to the carrier 8. Further, in each of the above-described embodiments, a tension urging force is applied to the carrier 8 so that the slider 7 and the carrier 8
The carrier 8 is pressed in the direction of the slider 7 by using the biasing force of an elastic member such as a coil spring, a plate spring, a bar spring, or rubber to connect the slider 7 and the carrier 8. Good.

[0029]

As described above in detail, according to the measuring apparatus of the present invention, the connection between the slider and the carrier is connected via the spherical surface and the concave portion receiving the spherical surface, and the spherical surface rotates in the concave portion. The center of the slider and the point at which the urging force is applied to the carrier from the slider or the midpoint between the plurality of points at which the urging force is applied, on a straight line parallel to the running direction of the slider, and in parallel with the running direction of the slider. By applying the tensile force, while absorbing the displacement between the slider and the carrier due to the meandering or undulation of the scale or the machine body, it is possible to prevent the generation of a mechanical vector heading in a direction other than the traveling direction of the slider, and to return. It is possible to prevent the occurrence of an error and a decrease in the repetition accuracy, and reduce the measurement error of the relative movement position and the relative movement distance.

[Brief description of the drawings]

FIG. 1 is a perspective view of a measuring device attached to a machine main body.

FIG. 2 is a perspective view of a detection unit and a scale.

FIG. 3 is a horizontal sectional view of a main part showing a state of a detection unit and a scale in a housing.

FIG. 4 is a main-portion horizontal cross-sectional view for explaining a state in which a position shift has occurred on the carrier side.

FIG. 5 is a horizontal sectional view of a main part of a measuring device according to another embodiment.

FIG. 6 is a main part horizontal sectional view of a measuring device according to still another embodiment.

FIG. 7 is a horizontal sectional view of a main part of a measuring device according to still another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Measuring device, 2 housings, 3 scales, 4 sliders, 5 carriers, 7 sliders, 8 carriers, 9 detection heads, 13 connecting portions, 14 arms, 15 first bearing portions, 15a spherical surface, 15b first spring Through hole, 1
6 second bearing portion, 16a concave portion, 16b second spring through hole, 17 coil spring, 18 locking pin

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F062 AA02 BC31 DD04 DD09 DD12 DD31 EE09 EE62 FF13 GG37 GG65 GG72 MM06 2F069 AA02 AA06 BB01 DD12 EE05 EE26 GG04 GG06 GG07 GG62 HH14 JJ13 MM14 NN14 MM04 MM07 PP05 PP19 UU15 VV02 VV21 VV35

Claims (1)

[Claims] 1. A scale having a flat and long scale provided with a scale for position detection along a longitudinal direction, and a detection head which runs on the scale and reads the scale to obtain a position detection signal. And a carrier connected to the slider and traveling the slider along the longitudinal direction of the scale, wherein the carrier has a protrusion protruding toward the slider along the traveling direction of the slider. A first bearing portion is formed and has a spherical surface at an end facing the slider. The slider faces the first bearing portion and receives the spherical surface of the first bearing portion. A second bearing having a substantially conical recess is provided, and the carrier and the slider are parallel to a running direction of the slider passing through the center of the spherical surface. An elastic member that is locked to the slider at one point on the straight line or at a plurality of points symmetrically positioned across the straight line, and that applies an urging force in a direction parallel to the running direction of the slider to the carrier. A measuring apparatus, wherein a spherical surface of the first bearing portion is pressed and connected to a concave portion of the second bearing portion.