JPS58205801A - Measuring head - Google Patents

Abstract

PURPOSE:To improve the efficiency of measurement by a constitution wherein a probe shaft can move to be displaced freely while a contact is made to touch a free curved surface constantly even when said surface, an object of the measurement, changes the direction. CONSTITUTION:In the automatic measurement, a probe shaft 4 moves along the free curved surface 81A of a work piece 81, which is an object of the measurement, and on the occaision, a motor 26 is driven by a control unit 77 to shift the direction of the actuation of a spring, whereby a contact 5 is made to touch the free curved surface 81A constantly. Accordingly, the probe shaft 4 rotates when it moves along a part wherein a reference track is not in accord with said surface 81A. This rotation of the probe shaft 4 is detected as components in the directions of rectangular X and Y axes by displacement detectors 41 and 42, while the displacement with the movement thereof in the direction of a Z axis is detected by a displacement detector 16. That is, the deviation of the track of the moved and displaced contact 5 from the reference track is detected in sequence, and detection signals thus obtained are input to a signal processing unit 76.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring head, and more particularly to an improvement in a measuring head for shape measurement.

As a method for measuring a two-dimensional or three-dimensional free-form surface using a shape measuring machine, a method has been proposed in which the coordinates of a plurality of points on the free-form surface are detected using a so-called touch signal zorobe and these are subjected to arithmetic processing. However, when using such a method, it is necessary to determine the coordinates of an extremely large number of points in order to measure a curved surface with a complex shape.
This method has disadvantages in that it is impossible to work quickly and requires the use of expensive arithmetic equipment.

Therefore, a method has already been developed in which the probe axis is moved along one curved surface and the curved surface shape is detected as a continuous signal.
Conventionally, if the orientation of a curved surface changes, the probe axis may not be able to match, and therefore sufficient measurement cannot be performed with one probe axis, resulting in poor measurement efficiency.

An object of the present invention is to provide a measuring spatula r with excellent measurement efficiency.

The present invention relates to a probe shaft having a contact at its tip.

a support means for supporting the probe shaft on the main body case and allowing movement of the contact with respect to the main body case; a biasing means for holding the probe shaft supported by the support means in a predetermined posture; and the contact. a displacement detector for detecting movement displacement with respect to the main body case, and the biasing means always biases the probe shaft toward the free-form surface to be measured so that the contact always comes into contact with the free-form surface. The object is to be achieved by making it possible to make contact with the free-form surface and detecting the displacement of the contact with respect to the main body case in contact with the free-form surface by the displacement detector.

An embodiment of the present invention will be described below based on the drawings.

1.2 shows an embodiment of the measuring head according to the present invention. In these figures, a movable part of the measuring machine body (not shown) is connected to the upper end side of the shank 1. ing. Note that the measuring machine body referred to herein includes a processing machine such as a numerically controlled machine tool.

A cylindrical case body 3 is fixed to the lower end side of the shank 1 via a thick-walled disc-shaped upper lid part 2, and a probe shaft 4 is housed inside the case body 3 along the center line of the case body 3. ing. A contact 5 is provided at the tip of the probe shaft 4, and the contact 5 protrudes beyond the lower end of the case body 3 by a predetermined length. In addition, the central axis of the probe shaft 4 is designed to overlap and coincide with the central axis of the shank l, and here, the direction of the central axis of the probe shaft 4 in a state where they overlap and coincide is the neutral axis direction. That is to say.

A sphere 6 is provided at the longitudinally intermediate portion of the probe shaft 4 . The center point of the sphere 6 is located on the axis of the probe shaft 4, and the circumferential surface of one sphere 6 forms a spherical circumferential surface portion 6A. Further, the probe shaft 4 is inserted through the center of a thick disk-shaped bearing member 7 near the lower side of the sphere 6.

Seven hemispherical spherical bearing surfaces are formed on the upper end surface side of the bearing member 7, and each of the seven spherical bearing surfaces is positioned concentrically with the spherical curved surface 6A.

A roller device 8 is provided between the spherical receiving surface 7A and the spherical circumferential surface 6A.
As shown in FIG.
Three bearings are held on each side of the trapezoidal plate? - a ball-shaped rolling ball 10. Probe shaft 4 supported by bearing member 7 via this rolling device 8
is rotatable in all directions about a point on the axis of the a-zo shaft 4, that is, the center point of the sphere 6.
Here, the support means for supporting the probe shaft 4 on the main body case 3 and allowing movement of the contact 5 with respect to the main body case 3 is a bearing member 7. having the spherical curved surface portion 6A and the spherical receiving surface 7A. and a roller device 8.

The lower half of the sphere 6 is fitted into the spherical receiving surface 7A, while a spring receiver 11 is fitted and fixed at a predetermined position below the bearing member 7 of the probe shaft 4.
A relatively weak compression coil spring 12 that urges the probe shaft 4 downward is interposed between the shaft and the bearing member 7 so as to surround the probe shaft 4. The device 8, the roller device 8, and the seven spherical receiving surfaces cannot be separated from each other. Further, a relatively short cylindrical body 13 is fixed on the upper end surface of the bearing member 7 so as to surround the upper half of the sphere 6, and the 9 rollers are supported by this cylindrical body 13. 8 is maintained in the proper position.

A thick ring-shaped fixing ring 15 is fitted onto the bearing member 7 via a ball bush 14, and the bearing member 7 is movable relative to the fixing ring 15 along the neutral axis direction of the probe shaft 4. Sh.

Furthermore, the movement displacement is detected by a displacement detector 16. The displacement detector 16 is.

Spindle 17 and spindle 1 vertically installed on bearing member 7
7, and a coil 2o supported by the main body case 3 via a support rod 19 so as to surround the core 18, and the core 18 is linearly displaced within the coil 20. It is configured as a differential transformer type detector in which the amount of displacement is detected as an electrical signal.

Further, the bearing member 7 and the fixing ring 15 are supported by the main body case 3 via a lower support member 21. The lower support body 21 is formed into a substantially stepped cylindrical shape in which approximately half of the lower end side is smaller in diameter than approximately half of the upper end side, and the bearing member 7 and A fixing ring 15 is placed. The fixing ring 15 is attached to the lower support 2
On the other hand, the bearing member 7 is biased upward by a coil spring 22 as a buffer member embedded in the support member 21, so that the upward movement of the bearing member 7 is facilitated. As a result, the momentum of the book's downward movement is relaxed.

The lower support body 21 is fitted into the lower end opening of the main body case 3? At the same time, it is fixed by the root.

A substantially ring-shaped rotating body 24 is rotatably fitted into the small diameter portion 21B on the lower end side of the lower support body 21.

The rotating body 24 is slidably held by a flange member 23 fixed to the lower end of the small diameter portion 21B, and a spur toothed gear portion 24A is carved on the outer circumference of the rotating body 24. A pinion 25 is meshed with the portion 24A. The pinion 25 is fixed to the output shaft of a motor 26 attached to the outer periphery of the lower support 21, and the motor 26 rotates the rotating body 24 reversibly.

A disk-shaped rotary disk 27 is provided at the lower end opening of the rotating body 24 so as to close the opening. Fixed via root. An insertion hole 27A is bored in the center of the rotary disk 27,
The probe shaft 4 is inserted through the insertion hole 27A with a predetermined gap.

Further, the base end of one spring 29 in the shape of a leaf spring is fixed to the upper end surface of the rotary disk 27 via a mounting plate 28 as a biasing means.

The tip of the spring 29 is rolled and engaged with the probe shaft 4 via a bearing 30 fitted and fixed to the probe shaft 4, and the probe shaft 4 is biased by the spring 29 to the neutral axis position. It is configured to be held in a predetermined posture tilted to the ground.

Further, on the opposite side of the spring 29 with respect to the probe shaft 4, a plate spring-shaped position regulating member 61 is fixed on the rotary disk 27, and the probe shaft 4 is tilted by the spring 29. The tilting state of the probe shaft 4 is regulated at this point.

Further, two displacement detectors 41 and 42 are provided on the bearing member 7 to detect the movement displacement of the contactor 5 with respect to the main body case 3 as the movement displacement amount of two components orthogonal to each other (see Fig. 2). reference). If these displacement detectors 41 and 42 are explained together, the displacement detectors 41 and 42 are similar to differential transformer type detectors, and are connected to a support rod 44 that is vertically installed on the bearing member 7 via a stand block 43. The coil 45 is fixed at a predetermined height, the core 46 is moved and displaced within the coil 45 along the radial direction of the probe shaft 4, and the core 46 is moved and displaced in the direction of movement of the core 46, that is, the radial direction of the probe shaft 4. The spindle 47 extends through the center of the core 46.

One end of the spindle 47 protrudes toward the probe shaft 4 side, and one end of an abbreviated movable piece 48 is fixed to this end. The movable piece 48 is supported by the bearing member 7 via the base block 43 by parallel springs 49, which are two leaf springs arranged parallel to each other. Each leaf spring of the parallel spring 49 has a small hole through which the spindle 47 is inserted, and shape retaining members 50 are attached to both sides of each leaf spring. The shape-retaining member 50 is formed into a rectangular plate shape of a predetermined thickness with a round hole 51 in the center, and the degree of deflection of the leaf springs held from both sides by the shape-retaining member 50 is adjusted. The spindle 47 and the movable piece 48, which are connected to the parallel spring 49, are configured to move parallel to each other and in the same direction along the horizontal direction.

An abutment pin 52 is provided on one side edge of the movable piece 48 to protrude toward the engagement piece 53 along the radial direction of the probe shaft 4 . The retaining piece 53 is made of a small sphere provided on the upper end of the probe shaft 4, while the mounting pin 5 is provided protrudingly on the upper end of the movable piece 48.
4 and a fixing pin 55 provided along the axial direction of the probe shaft 4 on the upper end side of the retaining piece 53, a relatively weak tension coil spring 56 is interposed between the spindle 4
7 is in constant contact with the retaining piece 53 via the movable piece 48 and the abutting pin 52.

Next, the operation of this embodiment will be explained with reference to FIG.

In FIG. 5, the main body case 3 is attached to a slider 72 of a measuring instrument main body 71, and the slider 72 has a drive section 7.
3 are connected. The displacement of the slider 72 is detected by the detection unit 74 as components in three axial directions orthogonal to each other. The detection signal detected by the detection unit 74 is input to the signal processing unit 76 of the measurement control unit 75.
.

A detection signal from 16 is also input.

The signal processing section 76 is connected to a control section 77, and the control section 77 sends control signals to the drive section 73 and the motor 26. Further, the control section 77 outputs the
Plotter 79. It is connected to a measurement result display device such as a printer 80° or CB, T (not shown).

The probe shaft 4 is manually moved along a reference body (not shown) and a trajectory program is stored in the control unit 77, and during automatic measurement, the probe shaft 4 is automatically moved following the trajectory program.

During automatic measurement, the probe shaft 4 moves along with the free-form surface 31AKa to be measured on the workpiece 81. At this time, the motor 26 is appropriately driven by the control section 77 to appropriately change the biasing force direction of the spring 29. , the contact 5 always comes into contact with the free-form surface 81A. Therefore, when the probe shaft 4 moves through a portion where the reference locus and the free-form surface 81A do not match, the probe shaft 4 rotates appropriately about the center point of the sphere 6. Such rotation of the probe shaft 4 is detected by the displacement detection paths 41 and 42 as components in the mutually orthogonal XIY axis directions, and movement in the Z axis direction perpendicular to the X and Y axes is detected by the displacement detector. 16, that is, the deviation of the movement displacement trajectory of the contactor 5 from the reference trajectory is sequentially detected, and this detection signal is input to the signal processing section 76.

The detection signal thus obtained is processed together with the detection signal from the detection unit 74 that detects the movement displacement of the slider 72, and the shape of the polygonal free-form surface 81A is drawn by the X-Y plotter 79. Alternatively, the printer 80 may record the deviation of the free-form surface 81A from the reference trajectory, or the deviation of the free-form surface 81A from the reference trajectory may be displayed.

This embodiment has the following effects.

Even if the orientation of the free-form surface 81A to be measured varies, the probe shaft 4 can be moved and displaced while the contact 5 is always in contact with the probe shaft 4, so that the measurement head can be moved as the orientation of the free-form surface 81A changes. There is no need to replace, etc., and therefore measurement efficiency can be improved. especially,
The probe shaft 4 can rotate in any direction around the center point of the sphere 6, and moreover, the probe shaft 4 can rotate in any direction around the center point of the sphere 6.
, even if the shape of the free-form surface 81A is complex, the contact 5 can be brought into continuous contact easily and quickly, and even if high-speed measurement is performed, measurement accuracy will not be affected. There is no risk at all.

Moreover, the structure as a whole is simple and manufacturing is easy.

In the above-described embodiment, the bearing member 7 was movable and displaced relative to the main body case 3 along the neutral axis direction of the probe shaft 4, that is, along the axial direction of the shank 1.
The bearing member 7 is fixed to the main body case 3 and no detector 16 is provided, and the displacement of the contactor 50 relative to the main body case 3 is detected only in two components in the X and Y directions in FIG. It's okay.

Although the displacement detectors 41, 42, and 16 are still differential transformer type detectors, they may be other types of displacement detectors such as photoelectric encoders or magnetic encoders. Furthermore, although the displacement detectors 41 and 42 are linear displacement detectors that are orthogonal to each other, they may not be orthogonal to each other,
It does not have to be a linear displacement detector. However, displacement detector 4
1. When 42 are linear displacement detectors that are orthogonal to each other, and the direction of the detected straight line matches the detection direction of each detector of the detection unit 74 of the slider 72, the signal processing unit 7
The signal processing in 6 is facilitated.

Further, the support means for allowing the movement of the contactor 50 relative to the main body case 3 is composed of six spherical circumferential parts, a bearing member 7, and a shaft device 8, but is not limited to this, for example, the probe shaft 4 is supported by the case body 3 so as to be rotatable on a virtual plane including the central axis of the probe shaft 4, and rotatable along the circumferential direction of the case body 30 together with the virtual plane. Good too. However, if configured as in the above-described embodiment, the contactor 5 can be moved quickly and easily in all directions, and the structure is simple.

Further, the roller mechanism 8 is not limited to the configuration shown in FIG. 3.4; for example, the retainer 9 may be a polygonal truncated pyramid other than a rectangular truncated pyramid, or a substantially hemispherical one. , rolling ball 1
The number of 0s is also not limited to the above case. However, according to the roller shearing device 8, each of the trapezoidal surfaces of the retainer 90 can be manufactured separately, so that it can be manufactured with great accuracy and precision. Since it can later be made into a truncated polygonal pyramid, it is easy to assemble, and from this point of view, it can be manufactured accurately and precisely, and the probe shaft 4 can be changed in attitude extremely smoothly.

Further, the biasing means for holding the probe shaft 4 in a predetermined posture, such as in the above case, a posture in which the contactor 5 is always in contact with the free-form surface 81A, is the spring 29, but the biasing means is not limited to this. A plurality of springs are provided around the probe shaft 4, and each of the plurality of springs simultaneously pulls the probe shaft 4 along the radial direction.

Alternatively, the probe shaft 4 may be held in the neutral axis direction by pressing or the like. In addition, although the biasing force direction of the spring 29 was assumed to be appropriately changed by the motor 26, the motor 26 was not provided, and the rotating body 24
may be manually rotated many times. Furthermore, spring 2
Although the tip of the spring 9 is rollingly engaged with the probe shaft 4 via the bearing 30, the tip of the spring 29 may be directly frictionally engaged with the curved surface of the probe shaft 4 without providing the bearing 30. However, if the rollers are configured to lock together, the biasing direction of the spring 29 can be changed extremely smoothly, and there is no adverse effect on measurement accuracy.

Furthermore, even if the 1-position regulating member 61 is not provided, the spring 2'
Although the posture of the probe shaft 4 biased by the coil spring 28 is not necessarily unstable due to the action of the compression coil spring 28, the presence of the position regulating member 61 has the effect of making it more stable. There is.

Further, in the above description, the case where υ automatic measurement is performed according to the present embodiment has been explained with reference to FIG. υ, the slider 72 may be used in which the cutting tool and the measuring head of this embodiment are automatically exchanged as appropriate. At this time, the machining accuracy may be successively measured using the Canadian Niprogram as it is. Furthermore, it can be used not only for automatic measurement but also for one-manual measurement.

As described above, according to the present invention, a measurement head with excellent measurement efficiency can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the overall configuration of an embodiment of a measuring head according to the present invention, FIG. 2 is a plan view of the embodiment with the top cover removed, and FIG. 3 is a head used in the embodiment. FIG. 4 is a plan view of the roller roller device, and FIG. 5 is an explanatory diagram showing one mode of use of the embodiment. DESCRIPTION OF SYMBOLS 1...Shank, 2...Upper lid part, 3...Main case, 4...Probe shaft, 5...Contactor, 6...Spherical body, 6 people...Spherical peripheral surface part, 7 ...Bearing member, 7A・
... Spherical bearing surface, 8 ... Roller seat device, 9 ... Retainer, 10 ... Rolling ball, 14 ... Goal bush, 1
5... Fixed + Jy gear, ta... Displacement detector, 24.
...Rotating body, 26...Motor, 27...Rotating plate%2
9... Spring as biasing means, 30... Bearing, 41 and 42... Displacement detector, 45... Coil, 46... Core, 47... Spindle. 48... Movable piece, 49... Parallel spring, 50... Shape retaining member. 52... Contact pin, 53... Engaging piece, 56... Tension coil spring, 61... Position regulating member. Agent Patent Attorney Minoru Kinoshita

Claims (1)

[Scope of Claims] (1) A probe shaft having a contact at its tip, supporting means for supporting the probe shaft in a main body case and allowing movement of the contact with respect to the main body case, and a support means for supporting the probe shaft with respect to the main case. A measuring head characterized in that it is equipped with a biasing means for holding a supported probe shaft in a predetermined posture, and a displacement detector for detecting displacement of the contact with respect to the main body case. (2. The measurement head according to claim 1, wherein the displacement detectors are two linear displacement detectors each in radial contact with the probe shaft and orthogonal to each other. (3) In claim 2, the linear displacement detector is a differential transformer type detector that is attached to the main body case and is biased so that -m of the spindle of the core is always in contact with the probe axis. A measuring head characterized in that: 1-(4) In any one of claims 1 to 3, the supporting means includes a spherical curved portion provided at a longitudinally intermediate portion of the probe shaft; a bearing member having a spherical bearing surface concentric with the spherical curved surface part; characterized in that a roller interposed between the spherical circumferential surface part and the spherical bearing surface is configured with a roller device; (5) In claim 4, the bearing member is supported by the main body case so as to be movable along the neutral axis direction of the probe shaft, and detects the displacement of the bearing member. A measuring head characterized in that a detector is provided. (6) In claim 4 or 5. The roller 9 device includes a retainer formed in a substantially polygonal truncated pyramid shape, and a A measuring head comprising three rolling balls held on each peripheral surface of the measuring head. The means consists of a single spring whose distal end is engaged with the probe shaft and whose proximal end is attached to the main body case side and which biases the probe shaft in the radial direction by ?f=3. (8) In claim 7, the tip of the spring has a roller secured to the probe shaft, and the base end of the spring has a main body rotatable around the probe shaft. A measuring head characterized in that it is attached to a case side. (9) In any one of claims 1 to 6, the biasing means biases the probe shaft so as to hold the probe shaft on a neutral axis. A measuring head characterized by comprising a plurality of springs that are biased in a radial direction.