JPS6344110A - Apparatus for inspecting surface roughness - Google Patents

Abstract

PURPOSE:To simply adapt the title apparatus to the quality control of a processing line and, especially, to suitably detect surface roughness, by discriminating a signal with specific frequency, which is determined by a speckle pattern and a scanning speed, from the signal inputted from a photoelectric converter. CONSTITUTION:A cylindrical roll 25 being an article to be inspected is placed on drive rollers 32 to be rotated and scanned at a constant speed with coherent beam from a laser beam source 21 driven by a scanning device. The reflected beam from the surface of said roll is formed into an image on a photoelectric converter 27 to form a speckle pattern. When the surface of the roll 25 is scanned at a constant speed by the coherent beam, a signal with specific frequency determined by a scanning speed and a speckle diameter is obtained from the converter 28. The output from the converter 28 is inputted to a discrimination device 31 and a signal with the frequency corresponding to the size of a speckle is calculated. The size of the speckle pattern is calculated on the basis of said signal and surface roughness is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a surface roughness inspection device for inspecting the surface roughness of an object to be inspected, such as a cylindrical roller of a bearing.

<Prior Art> Conventionally, there is a two-beam interference type surface roughness inspection device using laser light. This surface roughness inspection device uses a semi-transmissive mirror to split the laser beam from the laser light source into two directions: the object to be inspected and the target or reflective surface, and the laser beam reflected from the standard surface and the object to be inspected The resulting interference fringes allow for non-contact inspection of the surface roughness of the object to be inspected.

<Problems to be Solved by the Invention> However, the conventional three-ray one-step method surface roughness inspection device requires a standard reflective surface and requires highly accurate positioning of the object to be inspected. Second, there is the problem that it cannot be applied to a machining line for cylindrical rollers, for example. Nayoj, when measuring the roughness of cylindrical rollers,
In addition to measuring its absolute value;), it is often desirable to detect changes in relative values due to wear of processing tools, etc.

Therefore, the purpose of this invention is to eliminate the need for a standard reflective surface,
In addition, we provide a surface roughness inspection device that does not require highly accurate positioning of the inspected object, can be easily applied to quality control on processing lines, and is especially suitable for detecting changes in relative values of surface roughness. It's about doing.

Means for Solving the Problems> The surface roughness inspection apparatus of the present invention includes a coherent light source and a surface of an object to be inspected that is placed on a drive roller and rotated. A scanning device that scans at a constant speed, a photoelectric conversion device that photoelectrically converts coherent light reflected from the surface of the object to be inspected, and a speckle pattern and scanning speed are generated from signals manually input from the photoelectric conversion device. The present invention is characterized by comprising a deviation discriminating device that identifies a signal of a specific frequency determined by the above, and discriminates the surface roughness of the object to be inspected based on the signal of the specific frequency.

Function: The cylindrical test object is placed on the drive roller and rotated. A scanning device scans the surface of the object to be inspected with coherent light from a coherent light source at a constant speed -tt-
Ru. The light reflected from the surface of the object to be inspected is imaged on a photoelectric conversion device. A speckle pattern, that is, a bright and dark pattern is formed on this photoelectric conversion device. This speckle pattern is caused by the interference of the reflected light from the elliptical surface with the roughness of the reflective surface of the object to be inspected, and the size of this speckle pattern depends on the surface roughness of the object to be inspected and the coherent light It is determined by the wavefront curvature and the distance between the inspected object and each device.Since the wavefront curvature and the distance between the non-inspected object and each device are constant, the size of the speckle diameter on the light receiving surface of the photoelectric conversion device is determined by the roughness. Depends on.

Therefore, since the surface of the object to be inspected is scanned with coherent light at a constant speed, a signal of a specific frequency determined by the scanning speed and the speckle diameter is obtained from the photoelectric conversion device. The output from this photoelectric conversion device is input to a discrimination device to obtain a signal with a frequency corresponding to the size of the speckles, and the size of the speckle pattern is determined using this signal to determine the surface roughness. In particular, changes in the relative value of surface roughness can be easily recognized by changes in the output of the discriminator.

<Example> The present invention will now be described in detail with reference to illustrated embodiments.

In the first factor, 25 is a roller that is an object to be inspected that is placed on the driving rollers 32 and 32 and rotated. Reference numeral 20 denotes a light projecting device that illuminates the cylindrical surface of the roller 25, and this projecting device 20 includes a laser 21 and a moving mirror 22 as a scanning device.
and a condensing lens 23. 1, 26 is a Fresnel lens, 27 is a snout-shaped grating that emphasizes frequency components related to the speckle pattern, 28 is an electron multiplier (as a photoelectric conversion device), and 31 is a discrimination device, which is used for the second discrimination. The device 31 includes a low-pass filter 311 as shown in FIG.
and C (pass filter 313 and rectification smoothing circuit 312.31
・F is generated from the first operational amplifier 315.

In addition, Figure 2 shows the part of the scanning device that inspects the surface roughness of both end faces of the roller 25, and 20° and 20' are the projecting devices that irradiate laser light onto both end faces of the roller. It has the same configuration as the light projecting device 20 shown in FIG.

26° is a Fresnel lens, 27' is a slit-shaped grille, 28' is a photoelectronic amplifier, 33° is an amplifier, and 3B is a discriminator, which have the same configuration as shown in Figure 1. are doing.

In the above configuration, as shown in FIG.
The laser beam emitted from the vibrating mirror 22
The light passes through the condenser lens 23 and is scanned over the cylindrical surface 251 of the roller 25 from end to end along the central axis. The reflected light from the cylindrical surface 251 of this roller 25 is reflected by the Fresnel lens 25.
The frequency components of the optical signal related to the speckle pattern are further emphasized by a slit-like grating 27, and the light 7) is input to an amplifier tube 28. From the photoelectron amplifier tube 28, a signal representing the brightness of a speckle pattern as shown in FIG. The signal is input to the discriminator J731 after being amplified. In the discrimination device 31, as shown in FIG. 3, the signal from the amplifier 33 is passed through a low-pass filter 31.
The speckle butter with large ablation is passed through the signal shown in Table 4, and the bypass filter 313 allows the signal representing the speckle pattern with small particle size to pass through.

FIG. 5 is a diagram showing the characteristics of the low-pass filter 311 and the bypass filter 313, and fo represents the characteristic frequency. Each signal output from the low-pass filter 311 and the bypass filter 313 is transmitted to the rectifying and smoothing circuit 3.
12, 314, and is then rectified and smoothed and input to the half terminal and one terminal of the operational amplifier. Therefore, the operational amplifier 315 outputs a signal representing the difference in level between the low frequency signal (representing a speckle pattern with large grain size) and the high frequency signal (representing a speckle pattern with small grain size). Therefore, the output of the operational amplifier 315 represents the ratio of the rough portion to the rough portion of the surface roughness,
A change in the relative value of the surface roughness of the cylindrical surface 251 of the roller 25 is immediately detected by the output of the operational amplifier 315.

Since changes in the relative value of surface roughness can be detected immediately in this way, wear and tear on the machining tool can be immediately determined, making it suitable for online measurement of surface roughness in a machining line.

Note that the roller 25 is rotated by rotating the drive roller 32, and the above-mentioned inspection is performed on the entire cylindrical surface 25+ of the roller 25.

In Figure 2, the surface roughness is measured by scanning both end faces 252 and 253 of the roller 25.The only difference from Figure 1 is that both end faces 252 and 253 are scanned, and the pond is the same, so we will explain it below. Omitted.

In the above embodiment, the discrimination device 3! The low pass filter 31
1 and bypass filter 313, rectifier smoothing circuit 3i2
．． 314 and an operational amplifier circuit 315, for example, the discriminating device is constructed from an F-V converter, and the output voltage is set high for high frequencies as shown in FIG. (The finer the frequency, the higher the frequency.) Alternatively, the particulate dust component may be detected by the output of the F-V converter.

<Effects of the Invention> As is clear from the above, the surface roughness detection device of the present invention scans the surface of an object to be inspected with coherent light at a constant speed using a scanning device, and detects the reflected light from the surface of the object to be inspected. Coherent light is photoelectrically converted by a photoelectric conversion device, and a signal is manually sent from the photoelectric conversion device to a discrimination device to identify a signal with a specific frequency determined by the speckle pattern and scanning speed. Since the surface roughness of the object to be inspected is detected, there is no need for a standard reflective surface, there is no need for highly accurate positioning of the object to be inspected, and roughness measurement can be performed with high accuracy using a simple device on the processing line. ,
It is particularly suitable for detecting changes in relative values of surface roughness.

[Brief explanation of the drawing]

FIG. 1 is an optical system diagram for inspecting the cylindrical surface of a cylindrical roller according to an embodiment of the present invention, FIG. 2 is an optical system diagram for inspecting both end surfaces of the cylindrical roller according to the above embodiment, and FIG. 71 is a block diagram showing a speckle pattern, FIG. 5 is a diagram showing the characteristics of a low-pass filter and a low-pass filter, and FIG. 6 is a diagram showing the relationship between output voltage and frequency. 20... Light projecting device, 21... Light source, 25... Inspection object, 28... Photoelectric conversion device, 31... Discrimination device, 3
2... Drive roller. Patent applicant: Koyo Seiko Co., Ltd. Agent
Patent attorney Aoyama Aoyama and 2 others Figure 4 Figure 5

Claims (1)

[Claims] (1) A light source of coherent light, a scanning device that scans the surface of the cylindrical test object placed on a drive roller and rotated with the coherent light at a constant speed, and reflection from the surface of the test object. A photoelectric conversion device that photoelectrically converts the reflected light of the coherent light, and a signal of a specific frequency determined by the speckle pattern and scanning speed is identified from the signal input from the photoelectric conversion device, and based on the signal of this specific frequency, A surface roughness inspection device comprising: a discrimination device for discriminating the surface roughness of the object to be inspected.