JPH0421802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to measuring heads, and more particularly to improvements in measuring heads for shape measurements.

As a method for measuring a two-dimensional or three-dimensional free-form surface using a shape measuring machine, a method is known in which the coordinates of a plurality of points on the free-form surface are detected with a so-called touch signal probe and then arithmetic processing is performed. However, when adopting such a method, it is necessary to obtain the coordinates of an extremely large number of points in order to measure a curved surface with a complex shape, making it impossible to work quickly and requiring expensive calculations. The disadvantage is that a device must be used.

Therefore, a method is already known in which the shape of the curved surface is detected as a continuous signal by moving the probe axis along the curved surface, but in the past, if the direction of the curved surface changes, the probe axis may not be able to follow it, etc. However, sufficient measurement could not be performed with one probe axis, resulting in poor measurement efficiency.

The present invention includes a main body case, a probe shaft having a contact at a tip protruding from the main case and a spherical circumferential surface portion at a longitudinally intermediate portion, and the probe shaft is supported by the main body case and inserted through the probe shaft. A bearing member having a spherical bearing surface concentric with the spherical peripheral surface portion formed in the center thereof, and a polygonal pyramid-shaped retainer interposed between the spherical bearing surface of the bearing member and the spherical peripheral surface portion of the probe shaft. a rolling ball held on the circumferential surface of the retainer in a freely rolling manner; a spring that presses the probe shaft toward the bearing member; and a probe shaft supported by the bearing member via the rolling ball and the retainer. biasing means for holding the in a predetermined posture;
Two direct displacement detectors, each of which has a movable piece that is always urged to contact the probe shaft from the radial direction, and which are attached to the bearing member via a parallel spring and which detect linear displacement perpendicular to each other. It is characterized by having a container and.

Therefore, in the present invention, since the probe shaft freely rotates around the center point of the spherical circumferential surface, the contactor can freely move in the radial direction of the probe shaft, and when the probe shaft rotates, Friction and rattling in the contactor are prevented by the rolling device consisting of the polygonal pyramidal retainer and the rolling balls, and the probe shaft is always biased in an appropriate direction by the biasing means. can be quickly and accurately traced, and the displacement detector is capable of detecting the movement and displacement of the contact, thereby achieving the above object.

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

1 and 2 show an embodiment of the measuring head according to the present invention, and in these figures, a movable part of the measuring machine main body (not shown) is connected to the upper end side of the shank 1. There is. Note that the measuring machine body referred to herein includes a processing machine such as a numerically controlled machine tool.

A cylindrical main body case 3 is fixed to the lower end side of the shank 1 via a thick disk-shaped upper lid part 2, and a probe shaft 4 is housed inside the main body case 3 along the center line of the main body case 3. ing. A contact 5 is provided at the tip of the probe shaft 4, and the contact 5 protrudes from the lower end side of the main body case 3 by a predetermined length. Further, the central axis of the probe shaft 4 is designed to overlap and coincide with the central axis of the shank 1, and herein, the direction of the central axis of the probe shaft 4 in the overlapping and coincident state is referred to as the neutral axis direction. shall be.

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 the 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.
A hemispherical spherical bearing surface 7A is provided on the upper end surface side of the bearing member 7.
is formed, and the spherical receiving surface 7A is located concentrically with the spherical peripheral surface 6A.

A rolling device 8 is interposed between the spherical receiving surface 7A and the spherical peripheral surface 6A, and as shown in FIGS. 3 and 4, the rolling device 8 includes a truncated octagonal pyramid-shaped retainer 9 and a Three rolling balls 10 in the form of bearing balls are held on each peripheral surface of the trapezoidal plate shape of 9. The probe shaft 4 supported by the bearing member 7 via the rolling device 8 is rotatable in all directions about a point on the axis of the probe shaft 4, that is, the center point of the sphere 6. In this, the supporting means for supporting the probe shaft 4 on the main body case 3 and allowing the movement of the contactor 5 with respect to the main body case 3 includes the spherical peripheral surface portion 6A, the bearing member 7 having the spherical receiving surface 7A, and the rolling device 8. It is made up of.

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, and the spring receiver 11 and the bearing member A relatively weak compression coil spring 12 that urges the probe shaft 4 downward is interposed between the probe shaft 4 and the probe shaft 7 in a state surrounding the probe shaft 4. While being pressed by the member 7, the spherical peripheral surface portion 6A, the rolling device 8, the rolling device 8, and the spherical receiving surface 7A are brought into contact with each other under a predetermined pressure. 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 side of the sphere 6.
3, the rolling device 8 is maintained in a 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. ,
Further, the movement displacement is detected by a displacement detector 16. The displacement detector 16 is
It has a spindle 17 vertically disposed on the bearing member 7, a core 18 fixed to the upper end side of the spindle 17, and a coil 20 supported on the main body case 3 via a support rod 19 so as to surround the core 18. , is configured as a differential transformer type detector in which the amount of displacement of the core 18 linearly displaced within the coil 20 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 with a diameter of approximately half of the lower end side being smaller than that of the upper end side, and the bearing member 7 and A fixing ring 15 is placed. The fixing ring 15 is fixed to the lower support 21, and the bearing member 7 is biased upward by a coil spring 22 as a buffer member embedded in the lower support 21. This makes it easier to move, and the momentum of the downward movement is lessened.

The lower support body 21 is fitted into the lower end opening of the main body case 3 and fixed with bolts, and
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 collar member 23 fixed to the lower end of the small diameter portion 21B, and a spur 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 connected to a motor 26 attached to the outer periphery of the lower support 21.
is fixed to the output shaft of the rotating body 2 by the motor 26.
4 is adapted to be rotated reversibly.

A disk-shaped rotary disk 27 is fixed to the lower end opening of the rotating body 24 via bolts so as to close the opening. An insertion hole 27A is formed in the center of the rotary disk 27, and the probe shaft 4 is inserted through the insertion hole 27A with a predetermined gap. Further, a leaf spring-like spring 2 is attached to the upper end surface of the rotary disk 27 via a mounting plate 28 as a biasing means.
The proximal end of 9 is fixed.

The tip of the spring 29 is rollingly 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 toward the neutral axis position. It is configured to be held in a predetermined tilted posture. 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 when the probe shaft 4 is tilted by the spring 29, the probe shaft The tilt state of 4 is regulated.

Further, on the bearing member 7, there are two displacement detectors 41 for detecting the movement displacement of the contactor 5 with respect to the main body case 3 as the movement displacement amount of two components perpendicular to each other.
and 42 are provided (see Figure 2). If these displacement detectors 41 and 42 are explained together,
The displacement detectors 41 and 42 are composed of differential transformer type detectors, and include a coil 45 fixed at a predetermined height by a support rod 44 vertically installed on the bearing member 7 via a stand block 43, and a coil 45 fixed at a predetermined height. A core 46 that moves and is displaced along the radial direction of the probe shaft 4;
6, that is, along the radial direction of the probe shaft 4, the spindle 47 passes through the center of the core 46.
It is composed of.

One end of the spindle 47 projects onto the probe shaft 4, and one end of a substantially L-shaped 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 a parallel spring 49 consisting of two leaf springs arranged parallel to each other. Each leaf spring of the parallel springs 49 has a small hole through which the spindle 47 is inserted, and shape retaining members 50 are attached to each leaf spring from both sides. The shape-retaining member 50 is formed into a square plate shape with a predetermined thickness and a round hole 51 in the center.
Further, the degree of deflection of the leaf spring held from both sides by the shape retaining member 50 is adjusted, and the spindle 47 and the movable piece 48 connected by the parallel spring 49 are parallel to each other and in the same direction along the horizontal direction. It is configured to move and displace.

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 engagement piece 53 is made of a small sphere provided on the upper end of the probe shaft 4, and the attachment pin 54 protrudes from the upper end of the movable piece 48, and the engagement piece 5
A relatively weak tension coil spring 56 is interposed between a fixing pin 55 provided along the axial direction of the probe shaft 4 on the upper end side of the spindle 4.
7 is adapted to constantly abut against the engagement piece 53 via the movable piece 48 and the abutment pin 52. That is, the coil spring 56 urges the spindle 47 of the displacement detector against the probe shaft 4 via the movable piece 48 and the abutment 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
2 is connected to a drive section 73. Slider 7
The movement displacement of No. 2 is detected by the detection unit 74 as components in three axes 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.
Detection signals from 2 and 16 are 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. The control unit 77 also outputs an X-Y plotter 79 and a printer 8 via an output unit 78.
0 or a measurement result display device such as a CRT (not shown).

The control unit 77 manually moves the probe axis 4 along a reference body (not shown) and executes a trajectory program.
The probe shaft 4 is automatically fed in accordance with the trajectory program during automatic measurement.

During automatic measurement, the probe shaft 4 moves along the free-form surface 81A of the workpiece 81 to be measured. At this time, the motor 26 is appropriately driven by the control section 77, and the biasing direction of the spring 29 is controlled. is changed appropriately, and the contactor 5 always comes into contact with the free-form surface 81A. Therefore, the reference locus and the free-form surface 81A
When the probe shaft 4 moves through a portion where the two do not coincide with each other, the probe shaft 4 rotates appropriately about the center point of the sphere 6 as a rotation center. Such rotation of the probe shaft 4 is detected by the displacement detection paths 41 and 42 as components in the mutually orthogonal X and Y axis directions, and
The movement displacement 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 sent to the signal processing unit 76. is input to.

The detection signal obtained in this way may be 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 free-form surface 81A may be drawn by the X-Y plotter 79. , a free-form surface 81A with respect to the reference trajectory by the printer 80.
The deviation may be recorded or displayed on a CRT.

This embodiment has the following effects.

Even if the orientation of the free-form surface 81A to be measured varies, the biasing direction of the spring 29 is appropriately changed by the motor 26, and the probe shaft 4 can be moved and displaced while the contact 5 is always in contact with the probe shaft 4. , there is no need to replace the measuring head as the orientation of the free-form surface 81A changes, and therefore,
Measurement efficiency can be improved. In particular, since the probe shaft 4 can rotate in any direction about the center point of the sphere 6, and is provided with a rolling device 8, the free-form surface 81A
Even if the shape of the contactor 5 is complicated, the contactor 5 can be brought into continuous contact easily and quickly, and there is no risk of impairing measurement accuracy even when high-speed measurement is performed.

Further, the displacement detectors 41 and 42 are connected to parallel springs 49
Since it is supported by the bearing member 7 via the probe shaft 4, it is always in contact with the engagement piece 53 of the probe shaft 4 in an appropriate state, and accurate measurements can be performed. Moreover, since the probe shaft 4 is supported by the bearing member 7, even if the probe shaft 4 is displaced in the axial direction, the displacement detector 4 with respect to the probe shaft 4
The contact positions of the contact pins 52 of Nos. 1 and 42 do not change,
No error occurs due to this axial displacement.

Moreover, the overall structure is simple and manufacturing is easy.

In the above-described embodiment, the bearing member 7 was movable with respect 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. Case 3
and is not provided with a detector 16,
The displacement of the contactor 5 with respect to the main body case 3 is the fifth
In the figure, only two components in the X and Y directions may be detected.

Moreover, although the displacement detectors 41, 42, and 16 are differential transformer type detectors, they may be other types of displacement detectors such as a photoelectric encoder or a magnetic encoder.

Further, the rolling device 8 is not limited to the configuration shown in FIGS. 3 and 4. For example, the retainer 9 may be a polygonal truncated pyramid other than an octagonal truncated pyramid, and the number of rolling balls 10 may also be changed. The case is not limited to the above case. However, according to the rolling device 8, each of the trapezoidal circumferential surfaces of the retainer 9 can be manufactured separately, so that it can be manufactured with great precision and precision. Since it can later be made into a truncated polygonal pyramid, it is easy to assemble, and from this point of view as well, it can be manufactured accurately and precisely, and the probe shaft 4 has the advantage of being able to change its posture extremely smoothly.

Further, although the spring 29 is used as the biasing means for holding the probe shaft 4 in a predetermined posture, such as in the above case, the contact 5 always comes into contact with the free-form surface 81A, the probe shaft 4 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 along the neutral axis direction by pressing or the like. Further, the biasing direction of the spring 29 is determined by the motor 26.
However, motor 2
6 may not be provided, and the rotating body 24 may be rotated manually. Furthermore, the tip of the spring 29 was supposed to roll and engage with the probe shaft 4 via a bearing 30, but the bearing 30 is not provided and the tip of the spring 29 directly frictionally engages with the circumferential surface of the probe shaft 4. It can be anything. However, if the spring 29 is configured to be engaged by rolling, 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 position regulating member 61 is not provided,
The posture of the probe shaft 4 biased by the spring 29 is maintained at the neutral axis by the action of the compression coil spring 12, so it is not necessarily unstable, but it will be more stable if the position regulating member 61 is provided. It has the effect of becoming

Furthermore, in the above description, the case where automatic measurement is performed according to this embodiment has been explained with reference to FIG. 72
Alternatively, the cutting tool and the measuring head of this embodiment may be used while being automatically replaced as needed. At this time, the machining accuracy may be sequentially measured using the machining program as it is. Furthermore, it can be used not only for automatic measurement but also for 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 the 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 measurement head used in the embodiment. FIG. 4 is a front view showing an enlarged configuration of the rolling device, FIG. 4 is a plan view of the rolling device, and FIG. 5 is an explanatory diagram showing one mode of use of the embodiment. 1...Shank, 2...Top cover, 3...Main case, 4...Probe shaft, 5...Contact, 6...
Sphere, 6A... Spherical peripheral surface portion, 7... Bearing member, 7
A... Spherical bearing surface, 8... Rolling device, 9... Retainer, 10... Rolling ball, 12... Compression coil spring, 14... Ball bush, 15... Fixed ring, 16... Displacement detector, 24...Rotating body, 26
... Motor, 27 ... Rotating disk, 29 ... Spring as biasing means, 30 ... Bearing, 41 and 42 ... Displacement detector, 45 ... Coil as displacement detector main body, 46 ... Core, 47... Spindle, 48... Movable piece, 49... Parallel spring, 50...
... Shape retaining member, 52 ... Contact pin, 53 ... Engagement piece, 56 ... Tension coil spring, 61 ... Position regulating member.

Claims (1)

[Scope of Claims] 1. A main body case, a probe shaft having a contact at its tip protruding from the main case and having a spherical circumferential surface portion at a longitudinally intermediate portion, and a probe shaft supported by the main body case and having a spherical peripheral surface portion at a longitudinally intermediate portion thereof. A bearing member having a spherical bearing surface concentric with the spherical peripheral surface portion formed in the center portion to be inserted, and a polygonal pyramid interposed between the spherical bearing surface of the bearing member and the spherical peripheral surface portion of the probe shaft. a shaped retainer, a rolling ball rotatably held on the circumferential surface of the retainer, a spring that presses the probe shaft toward a bearing member, and a spring supported by the bearing member via the rolling ball and the retainer. a biasing means for holding the probe shaft in a predetermined posture, and movable pieces each of which is biased so as to constantly contact the probe shaft from the radial direction, and is attached to the bearing member via a parallel spring, and , two linear displacement detectors for detecting mutually orthogonal linear displacements. 2. The measuring head according to claim 1, wherein the linear displacement detector is a differential transformer type detector. 3. In claim 1 or 2, the bearing member is supported by the main body case so as to be movable along the direction of the neutral axis of the probe shaft, and a detector for detecting the displacement of the bearing member is provided. A measuring head characterized in that it is provided with a measuring head. 4. In any one of claims 1 to 3, the biasing means has a distal end engaged with the probe shaft, a proximal end attached to the main body case side, and a biasing means that extends along the probe shaft in the radial direction. A measuring head characterized in that it consists of a biasing spring. 5. Claim 4 is characterized in that the tip of the spring is rollingly engaged with the probe shaft, and the base end of the spring is attached to the main body case so as to be rotatable around the circumferential surface of the probe shaft. measuring head. 6. In any one of claims 1 to 3, the biasing means includes a plurality of springs that bias the probe shaft in the radial direction so as to maintain the probe shaft on the neutral axis. Measuring head featuring: