JPH0244005B2 - UEEBINESU * MEETANOSHOKUSHIN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a stylus used in a waviness measuring device such as a ball bearing or a roller bearing.

Conventionally, when measuring the surface roughness or waviness of parts (e.g. inner ring) that make up ball bearings, roller bearings, etc., the test surface of the test object is touched while the test object is being rotated at a constant rate. The displacement position of the needle is detected, and the average value of the displacement amount is taken as the waviness value. The displacement detecting means is called a waviness meter. Such wavyness
I will give a preliminary explanation of the meter's stylus using a diagram.

FIG. 1 is a perspective view showing the usage of the waveness meter stylus. In the figure, 1 is a test object (the one shown is the inner ring of a ball bearing),
It is rotated at a constant number of rotations in the direction of the arrow, for example, with oz as the axis. 2 is the tip of a cantilever that constitutes a power generation means that converts the amount of vertical displacement (oy direction) into an amount of electricity as shown in the figure, and 3 is a stylus attached to the tip of the cantilever, which generates a rotating object. The cantilever tip 2 contacts the test surface of the test object 1 to accurately measure the amount of displacement due to undulations on the test surface.
It is something that can be conveyed to people.

Since the stylus 3 contacts and rubs the surface to be inspected, which is the most important finished surface of the object 1, it must not cause scratches or scratches on the finished surface, and should not cause any friction. Since a material with a small coefficient is required, plastic materials such as nylon are generally used. On the other hand, since the stylus 3 is constantly rubbed and worn out, it is easily attached to the cantilever tip 2 by screwing, so that it can be easily replaced. FIG. 2 is an enlarged partial cross-sectional view of the stylus 3 that has been commonly used in the past. In the figure, 3 ₁
3 indicates the threaded part for attaching to the cantilever, and 3 ₂ indicates the tip of the needle, which is the end in contact with the test surface. The total length of stylus 3 is approximately
It is small, with a diameter of 12 mm and a needle tip of about 1 mm.

As the test object 1 rotates at a constant rotation speed, the unevenness and undulations on the test surface are communicated by moving under the tip ₃₂ of the stylus 3 at a constant speed, causing the stylus 3 to move up and down and vibrate. . Therefore, irregularities and undulations on the surface to be inspected can be detected as changes in the amplitude of vibrations with a constant period. For example, when the rotational speed of the test object 1 is 720 revolutions per minute, the period of the irregularities and undulations on the test surface, and therefore the frequency, is practically in the range of about 35 to 1200 Hz. Therefore, the frequency characteristics of the waviness meter are required to be flat in the above frequency range.

When the natural frequency of the waviness detection section including the stylus 3 is within the above frequency range, waviness
The flatness of the frequency characteristic of the meter is impaired, and an error occurs in the measured value near its own vibration frequency, which requires some kind of correction means to be taken.
The stylus made of a single nylon material, as shown in FIG. 2, which has been widely used in the past, cannot completely eliminate the above-mentioned drawbacks, and tends to produce peaks in characteristics, for example, around 800 Hz. Moreover, the characteristic peak changes and moves each time the stylus is replaced, so the correction amount has to be corrected each time, which is troublesome. On the other hand, the stylus must not cause any abrasions or scratches on the specimen, and the friction coefficient is small and the part that comes into contact with the specimen surface must be finished extremely smoothly, so plastic materials such as nylon are most suitable. As mentioned above, it has been frequently used.

The present inventor has discovered that when a conventional stylus molded from a single plastic material such as nylon is attached to a cantilever, the compliance seen from the end (needle tip) in contact with the test surface increases (rigidity decreases). result
We discovered that a resonance point occurs around 800Hz. Therefore, the present invention shifts the resonance point to higher than 1200 Hz by using a rigid metal as a part of the conventional single plastic stylus to create a composite stylus. .

3 and 4 are partially enlarged cross-sectional views showing two embodiments of the present invention. In the figure, 3'
shows the stylus according to the present invention as a whole, 4 is a metal part (e.g., brass), 4 ₁ is a threaded groove formed in the metal part 4, 4 ₂ is the tip of the metal part, and 5 is a plastic part (e.g.,
(nylon), 5 ₂ is the needle tip. In both embodiments, the plastic part 5 constitutes the part including the needle tip ₅₂ . In the example shown in FIG. 4, the outer diameter of the stylus 3' is smaller than that in the example shown in FIG. When these composite material stylus 3' are fixed directly to the metal mounting surface of the cantilever tip using the metal screw ₄₁ , the cantilever tip extends to the stylus metal tip ₄₂ , and the length of the vibration transmission path of the plastic part is the same as that of the metal part. It is functionally almost equivalent to shortening the tip 4 ₂ to the tip 5 ₂ of the stylus. Therefore, the compliance mentioned above is reduced (stiffness is increased) and the resonant frequency is reduced to 1200Hz.
In other words, we were able to shift the frequency range outside the high range limit required for a waviness meter and obtain extremely flat frequency band characteristics from the midrange to the low range.

FIG. 5A is a curve diagram showing an example of frequency characteristics when using a conventional nylon single material stylus, and FIG. 5B is a curve diagram showing an example of frequency characteristics when using a composite material stylus of the present invention. . If you compare the two figures, their superiority will be obvious.

As explained above, according to the present invention, the frequency characteristics can be greatly improved by simply replacing the conventional single-material stylus without any modification to the conventional waveness meter, and its effects is extremely significant.

Note that the present invention is not limited to the above-described embodiments, and can be modified and changed in various ways without departing from the gist of the invention as set forth in the claims.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing how the waveness meter stylus is used, Fig. 2 is an enlarged partial cross-sectional view showing a conventional example, and Figs. 3 and 4 are parts showing two embodiments of the present invention. An enlarged cross-sectional view, FIG. 5A is a curve diagram showing frequency characteristics of a conventional example, and FIG. 5B is a curve diagram showing frequency characteristics according to the present invention. 1... Test object, 3'... Waviness meter stylus, 4... Metal part, 5... Plastic part, 5
₂ ...The tip that comes into contact with the test surface of the test object.

Claims (1)

[Scope of Claims] 1. A plastic part forming at least a part including a tip that contacts the test surface of the test object, and at least the tip part is inserted near the contact tip of the plastic part, and a cantilever is inserted into the rear part of the plastic part. The wavyness is characterized by being composed of a metal part with a threaded part for attachment.
meter stylus.