JPS6145902A - Touch signal probe - Google Patents

Abstract

PURPOSE:To improve the sensitivity by arranging two piezoelectric elements which are interposed between a probe and a probe base in different axial directions, making up for directional characteristics of both piezoelectric elements mutually, and detecting the contacting of the probe in any direction with high sensitivity. CONSTITUTION:Three projection arms 22a-22c of the probe base 22 are placed on three receiving seats 26a-26c provided on the top surface of the receiving plate 14 of a probe case 18 at intervals of, for example, 120 deg., and the base 22 is pressed down by an energizing spring 28 and also controlled to one position according to the shape of the receiving seats 26a-26c. Further, coupling plates 40a-40d are mounted on four sides of a probe holder 36 having a square top surface through piezoelectric elements 46a-46d which sense shearing force or torsional force, and holding springs 44a-44d are fixed outside them with fixing plates 42a-42d. Then, when the force is applied to the probe 20 in the X-axis or Y-axis direction, the shearing force operates on the elements 46a-46d by moment around the base part of the holder 36 and when Z-axial force is applied, the upward shearing force operates; and outputs of the elements 46a-46d are put together into one output.

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 needle and a workpiece.

[Prior art] In three-dimensional coordinate measuring machines, etc., a probe is brought into contact with a workpiece placed on a base ten, and this contact point is measured three-dimensionally, thereby making it possible to accurately measure workpieces with complex shapes. It can perform 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. [1-45] Touch signal probes that automatically detect contact with a workpiece as electrical touch signals are widely used, and are used to automatically feed probes and automatically handle complex-shaped workpieces. It makes it possible to measure.

In the conventional general touch signal probe, 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 a workpiece, and six electrical contacts are provided on the support mechanism of the stylus in order to electrically output a touch signal.

In addition, since the contact point provided on the support part of the stylus is normally supported at three points, measurement becomes directional, and it is not possible to apply a stable measuring force in all directions. This is a problem because it causes errors and 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, it is possible to extract the compressive force (tension) applied to the piezoelectric element when it comes into contact with a touch work as an electrical signal, and this piezoelectric detection signal can be used as a touch signal. Ru.

However, using such compressive force (tension) /=
In addition to the pyroelectric effect that occurs due to environmental temperature changes, which causes errors, there was a need for a stable detector with a simpler structure, better detection sensitivity, and no directionality.

[Objective of the Invention 1] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to eliminate the color tube caused by temperature changes by using a piezoelectric element that is sensitive to shear force. The object of the present invention is to provide a highly sensitive and stable detector in the direction f1.

[Means for Solving and Overcoming the Problems] In order to achieve the above object, the present invention reduces the acting force generated when the stylus contacts the workpiece in the direction of compressive force (tension horn) on the piezoelectric element as in the past. , at least b2 piezoelectric elements sensitive to shear are inserted between the fusing layer and the stylus base so as to act in the direction of shear force, f<shear force, and these two piezoelectric elements each has a directionality in its sensitivity to the applied shear force, and in order to compensate for this directionality,
The two piezoelectric elements are arranged in different directions.

For this purpose, according to the present invention, the fusing layer is fixed to the touch 11 holder, and this fusing layer holder is connected to the touch 11 base by a connecting plate at λ1 in each axial direction, and the touch layer holder is connected to the touch base 11 by connecting plates. , at least two piezoelectric elements are orthogonally oriented between the holder and the connecting plate h
ing.

Both electrodes have the same piezoelectric detection direction characteristics, and their orthogonal arrangement allows the contact between the contact 11 and the workpiece to be
The acting forces in all directions are complemented by the combined output of both piezoelectric elements, making it possible to perform an extremely stable and highly sensitive touch signal detection operation.

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

Figures 1 and 3 show an embodiment of the touch signal 2J probe according to the present invention suitable for a coordinate measuring machine, and the base 10 fixed to the moving part of the coordinate measuring machine has a substantially ring-like shape. As for the side plate 12 and the receiver, a plate 14 is fixed to the g1 layer in sequence, and the outer periphery thereof is covered with a jJ bar 16 to form a case 18. Therefore, a handle a1 base 22 is supported inside the case 18, which supports a handle 20 via a connecting portion which will be described later.

As is well known, when the molten layer 20 is not in contact with the workpiece, the molten layer base 22, which has a diameter of 120 mm, is positioned at a rest position of t1i=- and does not move, and the stylus 20
When the stylus 20 comes into contact with the workpiece, it must be able to move in all directions to avoid retracting the stylus 20. For this purpose, the stylus base 22 in the embodiment J3 is shown in detail in FIG. Three protruding arms 22 at angular intervals of 120 degrees.
a, 22b, and 22c, and a supporting leg 24 having a spherical tip is fixed to each projecting arm by screws.

On the other hand, the receivers are provided on the upper surface of the plate 14 (1, as shown in detail in FIG. 3, each of the projecting arms 22ε), 22b, 22
Three receiving seats 26a, 26b, and 26c are fixed with screws in correspondence with c. The surface of the receiving seat 26a is flat, the receiving U seat 261) is formed on a catch bowl surface, and the receiving seat 26c is formed on a full surface. The contact base 22 is ensured that its static J1-position is 1f17. by the spherical surface coming into contact with these flat surfaces, the mortar surface and the V leak. It will be regulated by IgrffJ.

The stylus base 22 is pressed downward in FIG. A biasing spring 28 is inserted into.

9 That is, the upper end of the biasing spring 28 is screwed to the base 10! A spring holder with a pointed tip is engaged with a spring holder 30, and a spring holder with a pointed tip is fixed to the lower end of the spring holder.A bridge 32 is fixed to the upper surface of the stylus base 22. The holder is engaged with a seat 34.

As described above, the stylus base 22 in J3 in the Kinotsu example is fixed at a single resting position, and can move in all directions once the stylus 20 contacts the workpiece. The connection between the needle base 22 and the stylus 20 will be explained.

The fusing layer 20 is fixed to the stylus holder 36 with a screw 38, and in the embodiment, the stylus 2120 can be exchanged into any shape with respect to the stylus holder 36.

As shown in FIG. 3, the tactile eyebrow boulder 36 has a square upper surface, and each of its four sides is connected via a piezoelectric element (ru 40a, /10b, 40c,
/IOd is installed.

Then, on the outside of the connecting plate 40, +, L and a fixed plate /1 are provided.
2a, 42b, 42<:, 42d1. =Yo・) Retaining springs 4.4a, 44b, 44c, and 44d are firmly fixed with screws.

As shown in FIG. 1, the four retaining springs 44 shown in FIG.

Therefore, the stylus holder 36 has holding pins 4.4a, /14C.
C touch along Y direction by pair? 1 It becomes possible to move parallel to the base 22, and similarly, the leaf spring /I/Ib.

The handle 21 is supported movably with respect to the base 22 along the X direction by the pair 4/Id.

However, as shown in the figure, as a result of the stylus holder 36 being supported against the fusion layer v stand 22 by two orthogonal phases of parallel springs, in reality, the movement of the stylus holder 36 along the X axis is limited to the other side. Due to the longitudinal rigidity of the parallel leaf spring pair 448° 44G, it is impossible to move the tactile eyebrow holder 36 along the Y direction.
44d, the stylus holder 36 or the stylus 20 cannot be moved.
It functions to apply shear forces in the X and Y directions to a piezoelectric element, which will be described later, which is inserted between the stylus base 22 and the stylus base 22.

A characteristic feature of J3 in the present invention is that at least two piezoelectric elements are inserted and fixed in different directions at the connecting part between the stylus 20 and the stylus base 22. , piezoelectric elements 46a, 46b, 46G, and 46d are inserted and fixed between the four sides of the melting layer 36 and the connecting plate 40.

As shown in FIG. 1, these piezoelectric elements 46 are adhesively fixed between the stylus holder 36 and the connecting plate 40 with an insulating material interposed therebetween. Each piezoelectric element 46 is made of a PZTW ceramic piezoelectric element that is insensitive to compressive force and tensile force but sensitive to shear force and torsional force, and has a rectangular thin plate shape,
As a result of fixing the stylus holder 36 and the connecting plate 40 by these piezoelectric elements 46, the acting force when the stylus 20 contacts the workpiece is transmitted to the stylus base 22 via these piezoelectric elements 46. There's a lot of yelling. Therefore, for the piezoelectric element f,
A large acting force is applied when any workpiece comes into contact with the workpiece, and the important feature of the present invention is that this acting force is used as a shearing force or a torsional force f[along the direction of the thin plate surface of each piezoelectric element 46]. do.

In other words, compressive force or tension is normally applied to a piezoelectric element in a direction perpendicular to the plane of its thin plate, but according to this method of applying force, when a piezoelectric element is incorporated into a touch signal probe, It is extremely difficult to reliably apply the movement of the eyebrow 20 when it comes into contact with the workpiece in a direction perpendicular to the plane of the cable f, and depending on the Due to the moment force acting on the element, the size of the element must be small due to space constraints (
), and as a result, in the past, there was a problem in that the detection sensitivity was significantly reduced.

In the present invention, the tactile eyebrow 20 or the tactile i1 horg 36
A piezoelectric element that is insensitive to contraction and tension forces but sensitive to shear and torsional forces is arranged along the side surface of the piezoelectric element 5'120). The acting force is added as a shearing force when the workpiece contacts the workpiece, and the rotation center of the stylus holder 36, which is in a minute contact state, becomes the center of the holder 36, and when the stylus is contacted from any direction, In addition to acting on the element through torsional force and shear saw, the size of the structural element can also be increased, and at the current stage, this type of piezoelectric element for IYA disconnection pressure has higher sensitivity than the piezoelectric element for compression. Therefore, it is possible to extract a much larger piezoelectric output than before.

The piezoelectric element group according to the present invention described above has a shear force of ):
), but this shearing force exhibits specific directional characteristics with respect to the polarization direction of each piezoelectric element, and generally has a highly sensitive output characteristic with respect to the polarization direction and a high sensitivity output characteristic with respect to the polarization direction. It exhibits low sensitivity output characteristics in the orthogonal direction.

4.DELTA. and 4B respectively show the fixed arrangement direction of each piezoelectric element 46 according to this embodiment, and each piezoelectric element 46 is arranged so that its polarization direction is parallel to the Z axis. will be placed in

Therefore, it is equivalent to X ff4+
As shown in FIG. 4A, the piezoelectric elements 46b and 46d shown in FIG. Show li.

In any case, according to this embodiment, each ■-frost cable F46
An acting force in 7 directions is applied to -'') I=IIs, and since this coincides with the polarization direction, it is possible to generate a large output of 1 g.

FIG. 5 shows the output effect on each axis of the I-column according to the arrangement described above.

First, when an acting force is applied in the X-axis direction, through the tactile aim 20,
This acting force is applied to the stylus holder 36 as a moment 1 centered at the base of the holder 36, and the piezoelectric element/16b
There is a shearing force Zb (+) which is applied upward on the Z axis, and at -pj, there is a shearing force Zd (-) on the piezoelectric element 46d side.
A shearing force is generated toward the lower side of the Z-axis, and in response to this force f′1 in the A similar torsional moment is applied to the electric shock 46a, which act together as a shearing force on each piezoelectric element 46c, 46a.Thus, these piezoelectric elements 46a, 46b.

By adding the shearing force of 4.6c, /16d to its absolute value or squared value by 1, it is possible to obtain a highly sensitive detection signal.

Similarly, for the acting force in the Y-axis direction, the piezoelectric cumulative J″46
a, 46c act as a detection element, Z'a(+>('u) and 7C(-) on the piezoelectric element 46a side.
), and a shearing force due to the torsion moment acts on both the piezoelectric elements 46b and 46d, so that a good detection effect can be obtained by adding the absolute value or the sum of the two.

As mentioned above, the acting force in the X and Y@7j directions is ↑t
20 and the stylus holder 36 are used as levers, thereby generating an efficient cutting force in the piezoelectric element, making it possible to avoid a sufficiently sensitive detection effect even in a small-scale device.

Regarding the acting force in the Z-axis direction, an upward shearing force Za (+, ) along the Z-axis is applied to all piezoelectric elements r.

Acting forces Zb (+), Zc (+), and Zd (+) are generated, and the lever action of the stylus 120 and the stylus probe 36 is not applied to these, but the output of the group of four piezoelectric elements 46 is It becomes possible to obtain a detection effect that is more efficient in synthesis.

Furthermore, even if contact is made from any direction that is not along the X, Y, or Z axes, some type of shearing force or shear force or torsional force will act on each of the six elements r from the arrangement of these elements, resulting in high sensitivity. It is possible to cover detection regardless of directionality.

As described above, in this embodiment, - pairs of piezoelectric elements are arranged in the X and Y axis directions, respectively, and the touch '+1' is
It receives the acting force when it comes into contact with the material as a shearing force, and as a result, highly sensitive detection characteristics can be reduced by 1q.
By combining the outputs of both piezoelectric elements, it is possible to perform a high-sensitivity output action that is incomparable to the conventional simple piezoelectric output (CLJ) due to compression force (tension), and the touch signal It is possible to detect high-sensitivity touch signals without noise.

In the illustrated embodiment, a pair of piezoelectric elements are arranged in each of the X and Y directions, but in the present invention, each piezoelectric element C can perform a good detection action. In addition, in the figure, the two electric currents are arranged orthogonally, but this ノ:) arrangement is consistent with the structure of pu [] = - bu. It is possible to distribute force at a predetermined deflection angle.

In addition, in this embodiment, the distance between the melting layer and the touch base is 2.
Although they are connected by a pair of orthogonal parallel bones, this support mechanism can also be used as an arbitrary support l! ! [Effects of the Invention] As explained above, according to the present invention, a highly sensitive touch signal detection action is achieved by utilizing the signal output action due to the shear force of the piezoelectric element f. In addition, by using the two piezoelectric elements, it is possible to obtain an omnidirectional detection action that is t+', which is suitable for tap signal probes used in three-dimensional recordings, etc. This is extremely suitable.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing a preferred embodiment of the tap transmission block [1-1] according to the present invention, FIG. 2 is a sectional view taken along line II-IT in FIG. 1, and FIG. 3 is a support shown in FIG. 1. Figures 4Δ and 4B are respectively in the example. Detection characteristic diagram of the piezoelectric element f. Figure 5 is the piezoelectric element using shear force in this example. FIG. 3 is a perspective view of a main part illustrating the detection function of r. 18... Probe case, 20... Touch ε1. 22... Stylus base, 24... Support leg, 26... Receptacle seat, 36... Stylus holder, /IQ... Connection plate, 44... Support spring, 46... · 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, at least two piezoelectric elements that receive a shearing force generated between the stylus and the stylus base are inserted in a connecting portion between the stylus and the stylus base, and both piezoelectric elements are arranged in different axial directions. A touch signal probe is characterized in that it can detect contact of a stylus in all directions with high sensitivity by complementing each other's directional characteristics.