JPH0432569Y2 - - Google Patents

Description

[Detailed description of the invention] -Field of industrial application- This invention relates to a position detector that detects the position of the surface of an object placed in three-dimensional space using a contact needle. It's about structure.

As shown in Fig. 3, this type of position detector has a housing 1 that is attached to a tool holder 5 of a machine tool, and a contact needle 2 that extends from the housing and is held at a predetermined stable position. The position of the object to be measured 7 is detected by detecting the contact between the tip 3 of the contact needle 2 and the object to be measured 7 or the displacement of the contact needle 2 due to the contact.

Therefore, in this type of position detector, the contact needle 2 needs to be mounted so that it can be displaced relative to the housing 1 when an external force is applied due to contact with the object to be measured 7. Moreover, since the positional accuracy of the tip 3 of the contact needle directly affects the measurement accuracy, it is necessary to make the restoring accuracy of the contact needle sufficiently high when the external force is released, and furthermore, it is necessary to make it possible to provide mounting at low cost. , it is required to have a simple structure and be easy to process.

-Prior Art- Conventionally, structures shown in FIGS. 4 to 6 are known as support structures for contact needles. The one shown in FIG. 4 has three support rods 5 at the base 17a of the contact needle 2.
The contact needle 2
(For example, Japanese Patent Laid-Open No. 157447/1983).

In the device shown in FIG. 5, seats 54, 55, 56 and supports 57...57 are provided at the apex positions of a regular triangle on the base 17b of the contact needle and the housing 1b, respectively, and the biasing force of a spring 18b The contact needle 2 is supported by bringing the seat and the support into contact with each other. 5, the catch 54 is provided with a tapered hole 58, the catch 55 is provided with a V-groove 59, and the catch 56 is flat, and by the engagement of each with a ball 60 at the tip of a support 57, The position of the tip 3 of the contact needle 2 is regulated.

The one shown in FIG. 6 holds the tip 3 of the contact needle 2 in a fixed position by forming the receiving surface 61 on the side of the housing 1c into a partial spherical surface centered on the tip 3 of the contact needle. (for example, JP-A-Sho
58-151502).

-Problems that the invention attempts to solve- These structures are reasonably reasonable and, at least in theory, can hold the tip of the contact needle in place, and the tip of the contact needle can be held in place when the external force is released. Although the restorability is perfect, there is a problem in that positional errors of the contact needle occur due to processing errors, and extremely high processing accuracy is required.

That is, in the structures shown in FIGS. 4 and 5, the index error during machining between the housing side and the base side causes the contact needle 2 to be largely deviated from the axis, and especially in the structure shown in FIG. Since the processing modes of the seats 54 to 56 are different, it is almost impossible to obtain positional accuracy through processing, and there is a problem that position adjustment work after processing takes time. In addition, in the case shown in Fig. 6, the positional accuracy of the contact needle is determined by the processing accuracy of the spherical surface 61, so processing the spherical surface 61 requires man-hours and costs, and even if processing errors occur, this must be adjusted. The disadvantage is that it cannot be done.

In view of the above-mentioned problems, this invention is easy to process and assemble, processing errors have little effect on the positional accuracy of the contact needle, and post-processing adjustment is also easy, making the position detector as a whole extremely inexpensive. This was done with the aim of obtaining a structure that can be provided to

- Means for Solving the Problems - To explain using the reference numerals of the illustrated embodiments, the position detector of the present invention has a contact needle 2 attached to the base 17 of the contact needle 2.
3 forming each side of a regular triangle in a plane perpendicular to the axis of
Book grooves 21, 21, 21 are provided, and support protrusions 19, 19, 19 are provided in the portion 20 of the housing 1 facing the grooves 21, 21, 21 at positions that are the midpoints of each side of the equilateral triangle. The housing 1 and the base 17 can be implanted in one of them if necessary. coil spring 2 fitted to the other
2, the rotation of the contact needle is restricted to a narrower range.

- Effect - According to the above configuration, the base 17 of the contact needle 2 is
As shown in the figure, it is supported by engagement at three points between the support protrusion 19 and the groove 21. Since the three support protrusions 19 and the grooves 21 can be machined while indexing the housing 1 and the base 17 around their axes, the machining errors that occur can be reduced.
These are the relative error in the distance from the axis to the support protrusion 19 or the groove 21, and the index error. However, the distance error described above is absorbed by the relative rotation of the housing 1 and the base 17, and the index error is an error in the longitudinal direction of the groove 21. 19 only moves in the longitudinal direction of the groove 21, and the deflection of the contact needle 2 due to the index error is given by 1-cos (error/distance from the axis to the support point) and can be ignored. In the end, high positional accuracy of the contact needle 2 is guaranteed even if the processing accuracy is not very high, and the position of the tip 3 of the contact needle can be adjusted by making the height of the support protrusion 19 freely adjustable. is also easy.

-Example- Hereinafter, an example in which the displacement of a contact needle is detected by a change in capacitance will be described in detail based on FIGS. 1 and 2. FIG. 1 shows a cross section of the housing 1, which includes a head portion 1A, an intermediate portion 1A, and a middle portion 1A.
B and a shank portion 1C, which are integrally fastened together by threaded portions 8 and 9. 10 is an inner housing fitted into the intermediate housing 1B, 11 is an inner housing 10
12 is a spring receiving plate; 13 is a snap ring fitted to the inner diameter of the intermediate housing 1B; 14 is a snap spring 11;
The inner housing 10 and the spring receiving plate 12 are fixed in the intermediate housing 1B by the biasing force of the coil spring 14. A through hole 15 in the axial direction of the housing 1 is provided at the center of the inner housing 10, and a translation rod 16 is slidably inserted into the through hole 15.

17 is the disc-shaped base of the contact needle 2, 18 is the base 1
A compression coil spring 19 is interposed between the peripheral edge of the head side housing 1A and the intermediate housing 1B, and a leg member 19 projects from the peripheral edge of the bottom plate 20 of the head side housing 1A. As shown in FIG. 2, the leg members 19 are provided at each apex position of a regular triangle centered on the contact needle 2, and the disc-shaped base 17 has a leg member 19 that engages with the leg members 19. A V-groove 21 is provided. The contact needle 2 is pressed against the leg member 19 by the biasing force of the coil spring 18 and is held in a stable position in a three-point supported state. 22 is the head side housing 1
This is a coil spring erected on the bottom plate 20 of A, and this coil spring 22 is fitted into a through hole 23 provided in the base 17 of the contact needle, and functions to elastically suppress rotation of the contact needle 2.

The leg members 19 are connected to the head side housing 1, respectively.
It is screwed onto A, and by rotating it, the height of its protrusion can be adjusted. Further, a set screw 24 is provided at the threaded portion of each leg member for laterally pressing the set screw 24 to fix the rotation of the leg member 19 set at a predetermined height. As shown in FIG. 2, in the present invention, three leg members 19 are connected to a disk-shaped base 17.
Since the base 17 is positioned by engaging with the V grooves 21 arranged in a triangular shape, even if an error occurs in the position of the leg member 19, the contact needle 2
This error is absorbed by the slight eccentric movement or rotation of the contact needle 2, and the engagement between the leg member 19 and the V-groove 21 is reliably performed, ensuring highly accurate restorability of the contact needle 2 in a stable position. There is.

The tip of the translation rod 16 is pressed against the base 17 of the contact needle from the back side by the biasing force of a compression coil spring 26 interposed between the base 25 and the spring receiving plate 12. The inner housing 10 includes:
A disk-shaped fixed electrode plate 28 is fixed via an insulator 27, and this fixed electrode plate 28 faces a movable electrode plate 30 with an insulating plate 29 made of thin mica or the like interposed therebetween.

The movable pole plate 30 is slidably fitted to the linear rod 16 and is biased toward the fixed pole plate 28 by a compression coil spring 31 interposed between the movable pole plate 30 and the spring receiving plate 12 . This movable pole plate 30 has a set screw 3 for fixing it to the linear rod 16.
2, and a driver insertion hole 33 for rotating the set screw 32 is provided in the intermediate housing 1B. 34 is a removable rubber cap that blocks the driver insertion hole 33.

In the above configuration, if the set screw 32 is left in a loosened state, the movable electrode plate 30
Since the insulating plate 29 will be in close contact with the fixed electrode plate 28 with the insulating plate 29 sandwiched therebetween, the thickness of the insulating plate 29 should be precisely finished so that the desired electrode plate spacing is achieved. In this state, the shaft 4 of the housing 1 is attached to the rotating shaft, and while rotating the rotating shaft, the height of the leg member 19 is adjusted so that the tip of the contact needle 2 is accurately positioned on the rotational axis. At 24, the position of the leg member is fixed. Next, insert a driver through the driver insertion hole 33 and use the set screw 32 to tighten the movable electrode plate 30.
If fixed to the linear rod 16, the pole plates 28 and 30
The spacing is accurately set to a desired value determined by the thickness of the insulating plate 29.

When the tip 3 of the contact needle 2 comes into contact with the object to be measured 7,
The contact needle 2 is moved axially against the biasing force of the spring 18 or tilted as shown in phantom in FIG. In either case, the displacement of the contact needle 2 causes the translation rod 16 to move in the axial direction against the biasing force of the spring 26, so that the movable pole plate 30 fixed to the translation rod 16 by the set screw 32
is spaced apart from the fixed polar plate 28, and this is the bipolar plate 28,
30 is electrically detected by a measuring device (not shown), and the contact between the contact needle 2 and the object to be measured 7 is detected.

In the above embodiments, the contact between the contact needle and the object to be measured is detected by a change in capacitance. It goes without saying that the configuration of the present invention can be adopted regardless of the type of detection means.

-Effects of the invention- As described above, according to the configuration of the present invention, processing is simple, high positional accuracy of the contact needle is guaranteed even if there is a processing error, high positional accuracy and restorability are achieved, and contact after assembly is achieved. It is possible to obtain a support structure for the contact needle in which the position of the needle can be easily adjusted, and there is an effect that a highly accurate position detector can be provided at an extremely low cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is a front view of the contact needle. FIG. 3 is a side view showing how the position detector is used, and FIGS. 4 to 6 are explanatory diagrams showing the conventional structure. In the figure, 1 is the housing, 2 is the contact needle, 3 is its tip, 7 is the object to be measured, 17 is the base of the contact needle, 18
19 is a compression coil spring, 19 is a support projection, 20 is a bottom plate of the housing, 21 is a groove, and 22 is a coil spring.

Claims (1)

[Claims for Utility Model Registration] (1) In a position detector that measures the position or surface shape of an object by bringing the tip of a contact needle extending from a base supported by a housing into contact with the object, The base is a regular 3 in the plane orthogonal to the contact needle.
The housing has three grooves forming each side of the triangle, and a support protrusion is provided at the midpoint of each side of the regular triangle in a portion of the housing opposite to the groove, and these support protrusions and the groove are provided. A position detector, characterized in that it is provided with a bullet for press-fitting engagement. (2) The position according to claim 1 of the utility model registration claim, where the housing and the base are linked by a coil spring implanted in one of them and fitted in the other, and rotation of the contact needle is prevented. Detector.