JPS6145903A - Touch signal probe - Google Patents

Abstract

PURPOSE:To improve the sensitivity by fixing a probe to a probe base through an upper and a lower preloaded diaphragm and an upper and a lower probe holder which are fixed in their centers, and detecting the movement of the probe in three axial directions by piezoelectric elements. CONSTITUTION:The probe base 18 is pressed by three springs 36 toward a receiving plate 16 and positioned at a single stationary place according to the combination of three balls 32 and their receiving seats 28. Further, the base 18 is provided with diaphragms 38 and 40, the probe 20 is held on the upper diaphragm 38 through a supporting spring 48, and the probe 20 is coupled with a lower probe holder 56 fixed to the lower diaphragm 40 through X, Y, and Z axial piezoelectric elements 66, 62, and 70. Further, a force is so applied that a cut 68 moves horizontally corresponding to components of force on an X-Y plane to the probe 20, and a shearing force is applied to the elements 62 and 66. Then, the spring 36 operates not to move the lower diaphragm 40 against a Z-axial component of force and shearing force is applied to the element 70.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a touch signal probe, particularly a probe that uses a piezoelectric element to electrically detect contact between a stylus and a workpiece.

[Conventional technology] In a three-dimensional coordinate measuring machine, etc., a probe is brought into contact with a workpiece placed on a base, and this 1&touch point is measured three-dimensionally, thereby making it possible to accurately measure workpieces with complex shapes. It is capable of performing three-dimensional measurements, and is widely used in the precision measurement field.

In this type of measuring machine, a probe that can be moved manually or automatically in three-dimensional directions contacts the workpiece at a predetermined measurement point, and the feed coordinates of each axis at this time are read. In recent years, touch signal probes that automatically detect any contact with a workpiece as an electrical touch signal are widely used, and are used to automatically feed the probe and automatically measure workpieces with complex shapes. making it possible to do so.

In conventional touch signal probes, the stylus that contacts the workpiece is movably supported in the probe case.
It has a structure that absorbs the displacement of the stylus when it comes into contact with the workpiece, and in order to electrically output the touch signal, there is an 8-hammer structure between the stylus and the workpiece or at the base of the support mechanism of the stylus ↑4. Electrical contacts are provided.

However, in such conventional contact type probes, the contact point provided on the support part of the stylus is usually supported at three points, resulting in directional measurement, and it is difficult to measure in all directions. This is a problem because it is not possible to stably measure a force of 1 q, which causes a large error, and because such directionality cannot be corrected.

Other conventional touch signal probes have been proposed that do not use the electrical contacts described above but instead use other detection elements; for example, Japanese Patent Application Laid-Open No. 53-117464 discloses a probe that uses a piezoelectric element.

According to such a piezoelectric element, the compressive force (tension) applied to the piezoelectric element when the stylus contacts the workpiece can be extracted as an electrical signal, and this liver electromagnetic detection signal is used as a touch signal.

However, the piezoelectric element f using this condensed horn (tension) has the disadvantage that a pyroelectric effect occurs due to temperature changes, which causes noise.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to
The object of the present invention is to provide an isotropic, highly sensitive, and stable detector that is not affected by temperature changes.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a stylus base that has a single stationary position and is movably supported within the probe case. The diaphragms that are parallel to each other are fixedly supported along the construction surface of the base, stylus holders are fixed to both of these diaphragms, and the stylus is supported by these stylus holders. In this case, the stylus is fixed to an upper stylus holder by a support spring, and a piezoelectric element sensitive to shear is inserted between the stylus and the lower stylus holder.

A preload is applied to both the Guiaphrams in the direction of attracting or separating them, thereby reliably positioning the static position of the stylus in the vertical direction.

Further, according to the present invention, a piezoelectric element, preferably a piezoelectric element corresponding to each of the three axial directions, is inserted between the stylus and the lower stylus holder, so that the stylus contacts the workpiece and The detection voltage is extracted using the shearing force generated in each piezoelectric element.

Therefore, according to the present invention, the precise resting position of the stylus is determined, the mechanical sensitivity is increased by the mating of the diaphragm and the support spring, and the piezoelectricity of the piezoelectric element is Since the conversion effect is obtained from the shearing force, it is possible to provide a probe with extremely high electrical sensitivity.

[Example] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a preferred embodiment of the tap signal g probe according to the present invention, in which a case 10 is attached to a mounting bracket 1 fixed to the upper surface of the case 10; It is detachably attached to the movable part of a well-known three-dimensional coordinate measuring instrument.

A bottom plate 14 is screwed to the lower opening 10a of the probe case 10, and a substantially ring-shaped receiver plate 1G is clamped and fixed between the bottom plate 1/I and the probe case 10.

Inside the probe case 10, a stylus base 18 is movably supported while maintaining a single stationary position, and holds a stylus 20, which will be described later.

The stylus base 18 in the embodiment has a shape in which an upper plate 24 and a lower plate 26 are fixed to the upper and lower surfaces of a base spool 22,
The receiver rests on the plate 16 in a single rest position.

In other words, three seats 28a, 28b, and 28c are fitted on the plate 16 at approximately 120-degree intervals, and the lower plate 26 of the base 18 of the touch 11 corresponds to the seats 28, respectively. By inserting the ball receiver 30 between the receiver seat 28 and the ball receiver 30, the stylus base 18 can be positioned and placed in the correct position.

The three catch seats 28 each have a receiving surface with a different shape, and the catch seat 28a in FIG. As shown in FIG. 3, it consists of a groove and a planar shape, and the stationary position of the base 18 is reliably determined by each of these seats 28.

In order to place the base 18 of the tentacle 1 on the seat group 28, a spring receiver 22a is installed on the spool 22 of the tentacle 14 and a spring receiver plug 34 is fixed to the receiver plate 16.
A biasing spring 36 is installed between the stylus base 18, and by providing three springs 36 at approximately 120 degree intervals, the stylus base 18 is reliably pressed toward the receiving plate 16 and its stationary state 117 is maintained. It becomes possible to do so.

If the stylus 20 is connected to the stylus base 18 described above, the stylus 2
0 is the stylus base 1 when it comes into contact with a workpiece (not shown).
However, in the present invention, the stylus 20 is moved in a predetermined direction so that the stylus 20 can be moved with good sensitivity in each of the three axes of the stylus 20, that is, in the X, Y, and Z axis directions. a4
It is characterized by being supported by two diaphragms and one support spring with respect to the base 18.

That is, an upper diaphragm 38 and a lower diaphragm 40 as shown in FIG. 4 are firmly clamped and fixed between the spool 22, the soil member 24, and the lower plate 26 at their outer peripheries.

A one-touch 21 holder 42 is firmly fixed and held in the center of the upper diaphragm 38 by a washer 44 and a set screw 46.

The upper stylus holder 42 is connected to the stylus 20 by a support spring 18 that deflects against the force components of the stylus 20 on the XY plane. is firmly fixed to the stylus holder 42 by tightening the split ring 52 with the screw 50, and the ten end of the support spring 18 is connected to the stylus holder 5/I to which the stylus 20 is removably fixed. is fixed at the top of this.

A connection and fixing structure is achieved in which the upper stylus holder 42 and the stylus 20 are connected.

Further, a lower stylus holder 56 is firmly fixedly connected to the center of the lower diaphragm 40 with a washer 58 and a screw 60, similar to the upper stylus holder 42.

In the present invention, it is further provided that a piezoelectric element is inserted into the connecting portion between the lower stylus holder 56 and the stylus 20 to detect the contact of the stylus 120 with the workpiece using the means described later. The piezoelectric element is characterized in that the movement of the stylus 20 acts as a shearing force, and in the embodiment, H-shaped elements are provided in each of the three axial directions.

That is, on the lower surface of the lower stylus holder 56, a Y-axis pressure element TF62, a spacer 64, a piezoelectric cable 66, and a cup 68 are stacked and fixed, and both piezoelectric elements F62, 66 and 68 are stacked and fixed.
Each consists of a square or rectangular thin plate element.

A ring-shaped Z-axis pressure type element 70 is inserted between the cup 68 and the aforementioned stylus 11 receiver 5/'l, and from the above structure, the connection part between the lower stylus holder 56 and the stylus 20 is is sequentially 1. in the 3 axis directions. It is understood that an f-type element is provided.

The piezoelectric elements 62, 66, and 70 in this embodiment are each made of a reramic piezoelectric element such as PZT that is insensitive to compressive force and tensile force but sensitive to shear force and torsional force,
The Y-axis and X-axis piezoelectric elements 62 and 66 are respectively provided with voltage detection electrodes on their upper surfaces, and the Z-axis piezoelectric element 70 is provided with electrodes for taking out the detection mold 11 on its inner and outer peripheral surfaces.

In the present invention, each of the piezoelectric elements 62, 66° 70 has an action force applied between the stylus 20 and the lower stylus holder 56;
: The shearing force generated in each element based on the B electric effect contributes to the
When detecting IJ piezoelectricity using such shearing force, ↑1 has a directional characteristic that depends on the polarization direction as shown in Figure 5, and it is clear from the figure that when an acting force is applied in the polarization yj direction, high sensitivity is achieved. is obtained, but exhibits a low sensitivity characteristic Pl for an acting force in a direction perpendicular to this.

Therefore, in this embodiment, the Y-axis piezoelectric element 62 has its polarization direction parallel to the Y-axis, the X-axis piezoelectric element 66 has its polarization direction parallel to the X-axis, and the 7-axis piezoelectric element 70 has its polarization direction parallel to the X-axis. They are arranged parallel to each of the seven axes.

In the present invention, two parallel diaphragms 3 as described above are used.
8.40 is preloaded when it is assembled, and in the embodiment, the needle holder 42 is attached to the upper diaphragm 38.
When the upper diaphragm 38 is fixed to the upper diaphragm 38 and the upper diaphragm 40 is bent upward,
This causes the diaphragms 38, 40 to be preloaded so as to pull them together.

According to the present invention, the stationary position of the stylus 20 in the ZIN1 direction can be stabilized, and its mechanical sensitivity can be significantly increased by one.

In FIG. 1, inside the probe case 10, a printed circuit board 72 is provided around the touch assembly base 16, and piezoelectric elements 62, 66 in each axis direction are provided on this printed circuit board 72.
．． A preamplifier for impedance converting the detection signal from 70 is fixedly wired, and the detection signal can be preamplified inside the probe case 10.

The present embodiment has the above configuration, and its operation will be explained below.

In FIG. 1, the touch 21 base 181; i is constantly pressed against the receiving plate 16 side by three springs 36, and its position is determined by the combination of the receiving seats 28 corresponding to the three balls 32 and the screws. In the embodiment, the resting position of the instep can be reliably determined by the three receiving surfaces of the catch, the V, and the flat surface.

In addition, in the present invention, two diaphragms 38 and 40 are provided in parallel to the contact sub-base 18, which is placed in the J position, and the upper diaphragm 38 is The contact 1120 is held via the support pan 484, and the contact assembly 20 is connected to the lower contact bolt boulder 56 fixed to the lower diaphragm 40 via each pressure T5 element group, so that the contact between the two diaphragms is Assuming that the haptic 1120 assumes a single rest position with a preload applied to the
In response to a component force on a plane, the cup G8 moves horizontally with respect to the lower needle holder due to the deflection of the upper guyanoram 38 and the support spring 48, with the upper needle holder 42 at the rotation center 1). A force is applied to the XY piezoelectric elements 62 and 66, and a shearing force is applied to the XY piezoelectric elements 62 and 66, and a component force is applied to the 7-axis (in contrast, the upper diaphragm is acted on to reduce the preload, but the lower diaphragm is acted on by a spring). 3G force is also applied and acts to prevent movement of the stylus 20 with high sensitivity in each of the three axial directions due to the structure of the cup 168 and the stylus holder 54 connected to the lower diaphragm. How is it possible to detect contact?

In normal cases, the mechanical movement sensitivity of the touch signal probe in each axis direction is directional with respect to the force components on the X and Y planes, and also with respect to the force components of the Z axis with respect to the The ingredients were lacking in Kasamachi Publishing, such as poor sensitivity.

However, according to the invention, two parallel diaphragms 38 . As a result of holding the driving force 20 at the angle of /10, it is possible to obtain extremely high sensitivity to the 7I111 force direction, and the sensitivity in the XY axis direction is due to the deflection of the support spring 48 and the upper dianora 1138 that supports these deflections. is ensured by the slope of J:
Therefore, highly stable and isotropic and highly sensitive detection can be achieved in each of the three axial directions.

In addition, the mechanical movement of the touch a120 obtained in this way is electrically detected by the shear force of the J3-C piezoelectric element in the present invention, and the compressive force (tension ), it is possible to obtain a highly sensitive electrical detection effect using shearing force, so it is possible to reliably detect minute displacements such as JH on any contact port 1 of the workpiece. It is possible to capture it in a loud voice.

[Effects of the Invention] 42 As explained above, according to the present invention, touch
48 It is possible to position the stylus of the Shinkyu probe in a very stable stationary position, 62 and (to significantly improve the global and "11d" sensitivity, 66 It is possible to provide a 70-titch signal probe with less measurement error that is useful for two-dimensional coordinate measuring instruments and the like.

[Brief explanation of the drawing]

FIG. 1 shows a preferred embodiment of the touch signal probe according to the present invention.
2 and 3 are sectional rfA views showing the seat structure of the stylus base in FIG. 1. FIG. 4 is a plan view of the diaphragm in FIG. 1, and FIG. It is a characteristic diagram of the piezoelectric element used in the invention.・1 Stylus holder... Support spring... Stylus holder... Y-axis pressure type element... X-axis pressure type element... Z-axis piezoelectric element

Claims (1)

[Claims] (1) A stylus base carrying a stylus inside the probe case has a single stationary position and is supported in a movable position in multiple axes, and a touch signal electrically detects contact of the stylus with the workpiece. In the probe, an upper diaphragm and a lower diaphragm are supported above and below the stylus base and are arranged in parallel to each other, and an upper stylus holder and a lower stylus holder are respectively fixed to both diaphragms at the center of each diaphragm. The stylus is fixed to the upper stylus holder via a support spring having an isodirectional bending characteristic in the radial direction, and there is a gap between the stylus and the lower stylus holder. A piezoelectric element that receives the generated shear force is inserted and fixed, and a preload is applied to both diaphragms to determine the resting position of the stylus, and the movement of the stylus is controlled in three axes with high sensitivity. A touch signal probe for detecting a touch signal.