JPH05248847A - Measuring machine - Google Patents

Abstract

PURPOSE:To obtain a measuring machine, which guarantees the highly accurate measurement by enhancing the returning reproducibility of a probe shaft to the neutral position. CONSTITUTION:A shaking mechanism 11, which applies the mechanical vibration to a probe shaft 3, and a control device, which actuates the shaking mechanism 11 immediately before the contact of the probe shaft 3 and a material to be measured, are provided. When the probe shaft 3 and the material to be measured are moved in the mutually opposite directions, the mechanical vibration can be applied to the probe shaft 3 with the shaking mechanism 11 immediately before the next contact of the probe shaft 3 and the material to be measured even if the probe shaft 3 is not returned to the neutral position owing to the frictional force between each contactor shaft 4 and an electric contact mechanism 6 and the like. Therefore, the probe shaft can be positively returned to the neutral position by the mechanical vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring instrument using a touch signal probe for electrically detecting a contact state with an object to be measured. For example, it can be used for a coordinate measuring machine using a touch signal probe.

[0002]

BACKGROUND ART For example, in a coordinate measuring machine, a probe and an object to be measured placed on a surface plate are relatively moved in a three-dimensional direction, and a moment when the probe comes into contact with the object to be measured is captured. A touch signal probe is widely used that can electrically detect the contact state between the probe and the object to be measured and output it as a touch signal because the coordinate value in each feed axis direction is read as an electrical trigger.

As shown in FIG. 8, a touch signal probe which has been widely used in a conventional coordinate measuring machine has a case body 1 having a shank 1B and a probe shaft 3 having a contact ball 2 supported on the case body 1. Neutral axis L at the top of shaft 3
A support plate 5 having contactor shafts 4A, 4B, 4C that are orthogonal to the neutral axis L radially is provided at 120 degree intervals on the same circumference centered on (generally the same as the axis of the shank 1B). , An electrical contact mechanism 6A composed of a pair of conductive pins for sandwiching the contactor shafts 4A, 4B, 4C in a tapered shape from both sides on the circumference on a bottom wall 1A in the case body 1.
6B and 6C are provided, and these electrical contact mechanisms 6A,
6B, 6C is provided with a coil spring 7 for urging the support board 5 in the direction of the neutral axis L so that the contactor shafts 4A, 4B, 4C come into contact with each other.

Therefore, the probe shaft 3 includes three contactor shafts 4A, 4B and 4C and electric contact mechanisms 6A and 6 which are in contact with the contactor shafts 4A, 4B and 4C.
B, 6C and a coil spring 7 as an urging member hold the case main body 1 at a neutral position (a fixed position on the neutral axis L) and are supported so as to be displaceable and returnable with respect to the neutral position. There is. That is, it is supported so as to be displaceable in the direction of the neutral axis L and tiltable with respect to the neutral axis L, and to be capable of returning to the neutral position. Here, the contactor shafts 4A, 4B, 4C, the electric contact mechanisms 6A, 6B, 6C in contact with the contactor shafts 4A, 4B, 4C, and the coil spring 7 form a three-point support mechanism 8 having an escape mechanism. Further, the probe shaft 3 is provided by the contactor shafts 4A, 4B, 4C and the electric contact mechanisms 6A, 6B, 6C in contact therewith.
Detecting means 9 for electrically detecting the contact state between the object and the object to be measured
Are formed.

Now, when the contact ball 2 of the probe shaft 3 comes into contact with the object to be measured by the relative movement of the touch signal probe and the object to be measured, and then further moves slightly in the same direction, the probe shaft 3 moves to the object to be measured. Depending on the contact direction of the above, it is displaced in the direction of the neutral axis L or tilted with respect to the neutral axis L. Then, one of the contactor shafts 4A, 4B, 4C is separated from the corresponding electric contact mechanism 6A, 6B, 6C, and the electric contact mechanism 6A, 6B, 6C is opened, and as a result, a touch signal is output. As a result, the coordinate value in each axial direction at the time when the touch signal is output is read, and the size and shape of the object to be measured are obtained based on the coordinate value.

[0006]

In the structure of the conventional touch signal probe, the touch signal probe and the object to be measured move relative to each other in the direction away from the state where the touch signal probe and the object to be measured are in contact with each other in the next measurement. Then, it is considered that the probe shaft 3 is returned to the neutral position by the action of the coil spring 7. That is, due to the action of the coil spring 7, the contactor shafts 4A, 4B and 4C are connected to the electric contact mechanisms 6A and 6A.
It is considered that the stable positions of B and 6C are restored.

However, this is because the contactor shafts 4A, 4B, 4
When the frictional force between C and the electric contact point mechanism 6A, 6B, 6C is zero, the frictional force between the contactor shaft 4A, 4B, 4C and the electric contact point mechanism 6A, 6B, 6C is actually. , The contactor shafts 4A, 4B, 4C may not be able to return to the stable positions of the electric contact mechanisms 6A, 6B, 6C. In other words, the contactor shafts 4A, 4B, 4C may come to rest before the stable position of the electric contact mechanisms 6A, 6B, 6C.

Now, each electric contact mechanism 6 (6A, 6B, 6
When the frictional force between C) and the contactor shaft 4 (4A, 4B, 4C) is viewed microscopically, it can be approximated by a spring model as shown in FIG. When the manner of the action of the frictional force is shown by a spring model, various modes are conceivable as shown in FIGS. 10A, 10B, and 10C (there are various modes other than this). As is apparent from such a spring model, the action state of the frictional force in the static state varies depending on the closing direction of the electrical contact, and thus there is a drawback that the reproducibility of returning to the neutral position deteriorates.

Therefore, the contact surface between each contactor shaft 4A, 4B, 4C and each electric contact mechanism 6A, 6B, 6C is precisely finished to reduce the frictional force therebetween, or the contactor shaft is lubricated. 4A, 4B, 4C and electrical contact mechanism 6
A method of reducing the frictional force between A, 6B, and 6C can be considered, but in any case, since the frictional force cannot be reduced to zero, it cannot be said to be a drastic solution.

It is an object of the present invention to solve such a conventional problem and to reliably return the probe shaft of the touch signal probe to the neutral position, thereby improving the reproducibility of returning to the neutral position. It is to provide a measuring machine that guarantees high-precision measurement.

[0011]

Therefore, the measuring machine of the present invention is capable of holding the case body, the probe shaft, the probe shaft in the neutral position of the case body, and displace the probe shaft with respect to the neutral position. The touch signal probe includes a support mechanism including a biasing member that supports the return target and a detection unit that electrically detects a contact state between the probe shaft and the object to be measured, and the touch signal probe and the object to be measured. The probe shaft and the object to be measured are brought into contact with each other while being relatively moved, and the displacement amount in the relative movement direction is read based on the touch signal from the detection means, and the size or shape of the object to be measured is measured from this value. In the measuring machine, a vibrating mechanism for applying mechanical vibration to the probe shaft is provided, and the probe shaft and the measured object are read after reading the displacement amount in the relative movement direction. Provided a means for the operating the vibration mechanism one or more times until the object is then contacted, characterized in that.

[0012]

In the measurement, when the probe shaft and the object to be measured are brought into contact with each other while the touch signal probe and the object to be measured are relatively moved, the contact state of both is electrically detected by the detecting means. Then, the amount of displacement in the relative movement direction at that time is read. At this time, the probe shaft is displaced with respect to the neutral position, and damage to the probe is prevented.
After that, when the touch signal probe and the object to be measured are relatively moved in the direction of leaving, the probe shaft is returned to the neutral position by the action of the biasing member. At this time, even if the probe shaft is not accurately returned to the neutral position due to frictional force or the like, the vibration mechanism is operated once or twice or more before the probe shaft and the object to be measured come into contact with each other next time. As a result, since mechanical vibration is applied to the probe shaft by the vibration mechanism, the probe shaft can be reliably returned to the neutral position by the mechanical vibration.

[0013]

The preferred embodiments of the measuring machine of the present invention will now be described in detail with reference to the accompanying drawings. In the following description of the drawings, the same components as those in FIG. 8 described above will be designated by the same reference numerals, and the description thereof will be omitted or simplified.

First Embodiment A first embodiment is shown in FIGS. In FIG. 1, the base 5
A table 5 on which an object to be measured (not shown) is placed
Two are provided. Table 52 has a column 5
3 in the front-rear direction (Y-axis direction), the slider 55 in the left-right direction (X-axis direction) along the horizontal beam 54 of the gate-shaped column 53, and the Z-axis spindle 56 in the slider 55 in the vertical direction (Z-axis direction). Each of them is movable in the axial direction). A touch signal probe 57 is provided at the lower end of the Z-axis spindle 56. That is, the touch signal probe 57 and the object to be measured are configured to be relatively movable in the three-dimensional direction.

As shown in FIG. 2, the touch signal probe 57 has a vibrating mechanism 11 for applying mechanical vibration to the probe shaft 3 on a bottom wall 1A of the case body 1 at a position where it does not interfere with the support board 5. Is provided. Excitation mechanism 1
As shown in FIG. 3, 1 is composed of a laminated piezoelectric element 12 whose lower end is fixed on the bottom wall 1A of the case body 1, and a weight 13 provided on the upper end surface of the laminated piezoelectric element 12. There is.

FIG. 4 shows a control circuit. In the figure, the control device 61 includes, in addition to the touch signal probe 57, an X-axis drive system 62X and a Y-axis drive system that move the slider 55, the gate column 53, and the Z-axis spindle 56 in respective axial directions. 62Y and Z-axis drive system 62Z
Are connected to each other, and the slider 5
5, X-axis displacement meter 63 for detecting the displacement of each of the columnar column 53 and the Z-axis spindle 56 in the respective axial directions.
An X, Y-axis displacement meter 63Y and a Z-axis displacement meter 63Z are connected to each other.

The control device 61 drives the X-axis drive system 62X, the Y-axis drive system 62Y, and the Z-axis drive system 62Z according to a preset program to drive the probe shaft 3 of the touch signal probe 57 and the object to be measured. Contact. At this time, the operation signal is sent to the touch signal probe 5 immediately before the probe shaft 3 of the touch signal probe 57 comes into contact with the object to be measured.
7 is applied to the vibrating mechanism 11 to operate it once or several times. After that, at the time when the touch signal is output from the touch signal probe 57, the displacement meters 63X, 63Y,
The value of 63Y is read, and the size and shape of the object to be measured are obtained from these values. Here, the control device 61 constitutes means for operating the vibrating mechanism 11 once or twice or more until the probe shaft 3 and the object to be measured next contact after reading the displacement amount. ing.

Therefore, a measuring method by the above-described coordinate measuring machine will be described. First, with the shank 1B of the case body 1 attached to the lower end of the Z-axis spindle 56 of the coordinate measuring machine, according to a preset program,
The drive systems 62X, 62Y, 62Z are driven, and the touch signal probe 57 is moved in the three-dimensional direction. When the contact ball 2 of the probe shaft 3 comes into contact with the object to be measured, the probe shaft 3
Is inclined with respect to the neutral axis L or displaced in the direction of the neutral axis L depending on the contact direction with the object to be measured, and as a result, any one of the contactor shafts 4A, 4B, 4C corresponds to the electrical contact mechanism 6
Move away from A, 6B and 6C. Then, any one of the electrical contact mechanisms 6A, 6B, 6C is opened and the touch signal is output, so that the values of the displacement meters 63X, 63Y, 63Z at the time when the touch signal is output are read.

After that, the touch signal probe 57 is separated from the object to be measured, and immediately before the touch signal probe 57 comes into contact with the object to be measured, the vibrating mechanism 11 moves to
Operated once or several times. That is, the impulse signal is applied to the laminated piezoelectric element 12 once or several times. Then,
Since the laminated piezoelectric element 12 is displaced in the axial direction, the vibration of the weight 13 caused thereby is transmitted to the electrical contact mechanisms 6A, 6B, 6C and the probe shaft 3 via the bottom wall 1A of the case body 1.

Therefore, when the touch signal probe 57 relatively moves from the state of being in contact with the object to be measured to the direction of leaving for the next measurement, only the action of the coil spring 7 causes the contactor shafts 4A, 4B, 4C of the probe shaft 3 to move. Is an electrical contact mechanism 6
Even when the stable position of A, 6B, and 6C cannot be restored, at the time when the touch signal probe 57 and the object to be measured next come into contact with each other, mechanical vibration by the vibrating mechanism 11 causes
The contactor shafts 4A, 4B, 4C of the probe shaft 3 can be reliably returned to the stable positions of the electric contact mechanisms 6A, 6B, 6C.

Therefore, according to such an embodiment, since the vibrating mechanism 11 for applying mechanical vibration is provided on the probe shaft 3, the touch signal probe 57 is separated from the state in which the touch signal probe 57 is in contact with the object to be measured in the next measurement. When moving relative to the direction,
Even if the contactor shafts 4A, 4B, 4C of the probe shaft 3 cannot be returned to the stable positions of the electric contact mechanisms 6A, 6B, 6C only by the action of the coil spring 7, the mechanical vibration by the vibrating mechanism 11 causes , Contactor shaft 4 of probe shaft 3
Since the A, 4B and 4C can be reliably returned to the stable positions of the electric contact mechanisms 6A, 6B and 6C, the reproducibility of returning the probe shaft 3 to the neutral position can be improved.

Further, since the vibrating mechanism 11 is composed of the laminated piezoelectric element 12 and the weight 13, mechanical displacement occurs when a voltage is applied to the laminated piezoelectric element 12, whereby the weight 13 is caused.
Vibrates, it is possible to instantly generate mechanical vibration applied to the probe shaft 3. Moreover, since the overall size and size can be reduced, the case body 1 can be housed in the case body 1 without making the case body 1 larger than before, and the existing touch signal probe can be changed. Alternatively, the vibration mechanism 11 may be housed in the case body 1 to configure the touch signal probe 57 of this embodiment.

Further, in the measurement, the vibrating mechanism 11 is operated once or several times immediately after the touch signal probe 57 and the object to be measured are separated from each other, and immediately before the next contact.
If the touch signal probe 57 and the object to be measured are moved relative to each other until they come into contact with each other next, the contactor shafts 4A, 4B, 4
Even when C is displaced from the stable position of the electrical contact mechanisms 6A, 6B, 6C, when the touch signal probe 57 and the object to be measured next come into contact with each other, the mechanical vibration of the vibrating mechanism 11 causes the probe axis. 3 contactor shafts 4A, 4B,
4C can be returned to the stable position of the electrical contact mechanisms 6A, 6B, 6C.

Second Embodiment A second embodiment is shown in FIG. The touch signal probe 57 used in this embodiment is different from that of the first embodiment in that the vibrating mechanism 11 is used.
Are mounted on the support board 5 of the probe shaft 3, but are functionally the same. However, the probe axis 3
The first embodiment is preferable in terms of not increasing the load.
The mechanical structure and control circuit of the coordinate measuring machine are the same as in the first embodiment.

Third Embodiment A third embodiment is shown in FIGS. 6 and 7. In the touch signal probe 57 used in the present embodiment, the laminated piezoelectric element 12 is provided midway along the probe shaft 3 coaxially therewith. Here, the laminated piezoelectric element 12 constitutes the vibration mechanism 11,
In addition, it also constitutes detection means 9 for detecting the contact state between the probe shaft 3 and the object to be measured. In this case, as shown in FIG.
One of the relay contacts 21 of the relay 21 is attached to the laminated piezoelectric element 12.
A drive circuit 22 for applying an impulse signal or a sine wave signal to the laminated piezoelectric element 12 is connected via A, and
The amplifier circuit 2 is connected to the other relay contact 21B of the relay 21.
The contact signal detection circuit 24 is connected via 3. In this case, the contactor shafts 4A, 4B, 4C and the electric contact mechanisms 6A, 6B, 6C in contact with the contactor shafts 4A, 4B, 4C merely constitute a support mechanism 8 having an escape mechanism.

In this way, by switching the relay 21, it is possible to apply an impulse signal or a sine wave signal to the laminated piezoelectric element 12 to generate mechanical vibrations, and at the same time, the probe shaft 3 and the object to be measured are separated. The voltage generated in the laminated piezoelectric element 12 by the contact can be detected by the contact signal detection circuit 24 via the amplifier circuit 23. Therefore, in addition to the effect described in the first embodiment, the piezoelectric conversion element 12
Only by this, mechanical vibration can be applied to the probe shaft 3 and the contact state between the probe shaft 3 and the object to be measured can be electrically detected.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to these embodiments, and various improvements and design changes can be made without departing from the gist of the present invention. Is possible. For example, as the vibrating mechanism 11, the structure including only the laminated piezoelectric element 12 described in the above embodiment, or the laminated piezoelectric element 12 and the weight 1 is used.
The configuration is not limited to 3, and any motor such as a motor, an electromagnetic actuator such as a solenoid coil, or an actuator using air may be used as long as it can generate vibration.

The timing of activating the vibrating mechanism 11 is not limited to just before the probe shaft 3 and the object to be measured come into contact with each other during the next measurement. It can be any time until the contact. Furthermore, the number of operations may be arbitrary.

Further, the support mechanism 8 is not limited to the structure of the three-point support mechanism 8 described in the above embodiment, but may be appropriately selected according to the type of the measuring machine using the touch signal probe. For example, in the case of a touch signal probe used in a measuring instrument such as a height gauge, the probe shaft is rotatably supported with respect to the main body of the case, the probe shaft is held in a neutral position, and the probe shaft is centered around a rotation fulcrum. Alternatively, a supporting structure that is supported so as to be pivotally displaceable and capable of returning to the neutral position may be used. That is, the structure of a two-way touch signal probe may be used.

Further, the detecting means 9 is also composed of the contactor shafts 4A, 4B, 4C and the electric contact mechanisms 6A, 6B, 6C in contact with the contactor shafts 4A, 4B, 4C described in the above embodiment, or the laminated piezoelectric element 12. Alternatively, a closed loop circuit may be configured to be closed only when the probe shaft and the object to be measured contact each other, and the touch signal may be issued when the circuit is closed.

In the above embodiment, the coordinate measuring machine having the structure in which the touch signal probe 57 automatically moves in the three-dimensional direction according to the preset program is targeted. It is not limited to. The touch signal probe and the object to be measured can be manually applied to a measuring machine configured to be relatively movable in one axis direction or two axis directions. For example, it can be applied to a height gauge or the like. In this case, as means for operating the vibrating mechanism 11 once or twice or more until the probe shaft 3 and the object to be measured next contact after reading the measured value,
It may be configured with a manual switch.

[0032]

As described above, according to the measuring machine of the present invention,
You can surely return the probe shaft to the neutral position,
It is expected that the reproducibility of returning the probe shaft to the neutral position can be improved and high-precision measurement can be guaranteed.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a perspective view in which a part of the touch signal probe shown in FIG. 1 is cut away.

FIG. 3 is a front view showing the vibration mechanism of FIG.

4 is a block diagram showing a control circuit of the measuring machine of FIG. 1. FIG.

FIG. 5 is a partially cutaway perspective view showing a touch signal probe used in a second embodiment of the present invention.

FIG. 6 is a front view showing a main part of a touch signal probe used in a third embodiment of the present invention.

FIG. 7 is a diagram showing a drive circuit for a laminated piezoelectric element in the embodiment of FIG.

FIG. 8 is a partially cutaway perspective view showing a conventional touch signal probe.

9 is a diagram in which a frictional force in the vicinity of the electric contact mechanism of FIG. 8 is approximated by a spring model.

10 is a view exemplifying how a frictional force acts by the spring model of FIG.

[Explanation of symbols]

 1 case body 3 probe shaft 4A, 4B, 4C contactor shaft 6A, 6B, 6C electrical contact mechanism 7 coil spring (biasing member) 8 support mechanism 9 detection means 11 vibration mechanism 12 piezoelectric transducer element 13 weight 57 touch signal Probe 61 controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Market Aki 165 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Mitutoyo R & D Co., Ltd. In-house

Claims (1)

[Claims] 1. A support mechanism including a case body, a probe shaft, and a biasing member for holding the probe shaft in a neutral position of the case body and supporting the probe shaft so as to be displaceable and returnable to the neutral position. There is a touch signal probe including a detection unit that electrically detects a contact state between the probe shaft and the object to be measured, and the probe shaft and the object to be measured while relatively moving the touch signal probe and the object to be measured. To read the amount of displacement in the relative movement direction based on the touch signal from the detection means, in the measuring machine for measuring the size and shape of the object to be measured from this value, mechanical vibration to the probe shaft A vibrating mechanism for adding is provided, and the vibrating mechanism is activated until the probe shaft and the object to be measured next contact after reading the displacement amount in the relative movement direction. It provided with means for actuating times or more than once, measuring, characterized in that.