JP2015059861A - Hardened layer inspection method and inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique of accurately inspecting whether a hardened layer has been formed with a uniform thickness on a surface of a sheet-like metal plate without deforming or damaging the metal plate.SOLUTION: An inspection apparatus 1 for inspecting a hardened layer Ra formed on a surface of a ring R includes: a pair of rollers 10, 10 for moving the ring R along a longitudinal direction while applying an external force equal to or less than elastic limit; a light source 30 for emitting light toward an outer peripheral surface of the ring R so that a straight line L of light inclined with respect to longitudinal and lateral directions of the ring R appears on the outer peripheral surface of the ring R; an imaging apparatus 40 which images a portion on the outer peripheral surface of the ring R irradiated with the light source 30 to acquire an image including the line L of light; and an analyzing apparatus 50 which determines that an insufficient-thickness defective part of the hardened layer Ra exists in a position in the ring R where the line L of light is deformed when the line L of light is deformed in the image.

Description

  The present invention relates to a technique for inspecting a hardened layer formed on the surface of a sheet-like metal plate.

  Conventionally, a technique for inspecting whether a hardened layer (for example, a nitride layer) is formed on a surface of a sheet-like metal plate with a uniform thickness is widely known.

For example, Patent Document 1 discloses a technique for inspecting whether or not a nitride layer is formed with a uniform thickness on the surface of a ring used in a continuously variable transmission.
According to the technique disclosed in Patent Document 1, a process of performing an oxidation process after a nitriding process is added to the ring, and a part where the nitriding process is appropriately performed and a part where the nitriding process is not performed are made different from each other. By changing, it is possible to determine whether or not the nitride layer is formed with a uniform thickness due to the difference in color.

  However, in the technique disclosed in Patent Document 1, the ring may be thermally deformed by the oxidation treatment. In addition, since the quality of the nitriding process is determined based on the difference in color, there is a possibility that different determinations may be made depending on the operator.

JP 2009-007612 A

  It is an object of the present invention to provide a technique capable of accurately inspecting whether a hardened layer is formed with a uniform thickness on the surface of the metal plate without deforming and damaging the sheet-like metal plate. To do.

  An inspection method according to the present invention is an inspection method for inspecting a hardened layer formed on a surface of a sheet-like metal plate, and the metal plate is elongated while applying an external force below an elastic limit to the metal plate. And moving toward the surface of the metal plate so that linear light streaks inclined with respect to the longitudinal direction and the short-side direction of the metal plate appear on the surface of the metal plate. And when the light streak is not distorted, it is determined that there is no defective portion where the thickness of the hardened layer is insufficient in the portion where the light streak is located on the metal plate. Determining that there is a defective portion with insufficient thickness of the hardened layer at the position where the light streaks are distorted in the metal plate when the light streaks are distorted.

  An inspection apparatus according to the present invention is an inspection apparatus that inspects a hardened layer formed on a surface of a sheet-like metal plate, and applies the external force below the elastic limit to the metal plate while extending the metal plate in a longitudinal direction. A plurality of rollers that move along the direction and linear light streaks inclined with respect to the longitudinal direction and the short side direction of the metal plate so as to appear on the surface of the metal plate. A light source that emits light, an imaging device that captures an image of a portion of the surface of the metal plate that is illuminated by the light source, and acquires an image including the light streaks; In the case where it does not occur, it is determined that there is no defective portion where the thickness of the hardened layer is insufficient in the portion where the light streak is located in the metal plate, and the light streak is distorted Is the streak of light in the metal plate The distorted position, anda determining analyzer defective portion thickness is insufficient for the cured layer is present.

  ADVANTAGE OF THE INVENTION According to this invention, it can test | inspect accurately whether the hardening layer is formed in the surface of the said metal plate with uniform thickness, without deform | transforming and damaging a sheet-like metal plate.

The side view which shows the inspection apparatus which concerns on this invention. FIG. It is a figure which shows the streak of the light which appeared on the outer peripheral surface of a ring, (a) shows the case where light is irradiated to the part which is not a defective part in a ring, (b) shows light to the defective part of a ring. The case of irradiation is shown. It is a partial expanded sectional view of a ring, (a) shows the case where a defective part does not exist in a ring, (b) shows the case where a defective part exists in a ring.

Below, with reference to drawings, inspection device 1 which is one embodiment of the inspection device concerning the present invention is explained.
The inspection apparatus 1 is an apparatus that inspects whether or not the cured layer Ra is formed on the surface of the ring R with a uniform thickness.
The ring R is an embodiment of a sheet-like metal plate according to the present invention, and is an annular metal plate used for a continuously variable transmission. The ring R has a hardened layer Ra and a base material Rb (see FIG. 4).
The hardened layer Ra is a layer for improving the strength of the ring R and the like. Examples of the hardened layer Ra include a nitride layer formed by nitriding treatment. The hardened layer Ra is formed so as to cover the surface of the base material Rb.
The base material Rb is a part other than the hardened layer Ra in the ring R.

  As shown in FIG. 1, the inspection device 1 includes a pair of rollers 10, 10, a roller control device 20, a light source 30, an imaging device 40, and an analysis device 50.

The roller 10 is formed in a cylindrical shape and is configured to be rotatable around an axis. In this embodiment, two rollers 10 and 10 are provided.
The pair of rollers 10 and 10 are arranged at a predetermined interval from each other. The pair of rollers 10 and 10 support the ring R in a state where the outer peripheral surfaces thereof are in contact with the inner peripheral surface of the ring R, and rotate in the same direction (see the black arrows in FIG. 1). Rotate R at a fixed position. In other words, the ring R is wound around the pair of rollers 10 and 10 and is rotated by the pair of rollers 10 and 10 along the longitudinal direction of the ring R.

The roller control device 20 is electrically connected to and controls the pair of rollers 10 and 10.
The roller control device 20 is configured to be able to rotate the pair of rollers 10 at a predetermined rotational speed.
In addition, the roller control device 20 is configured to be able to move the pair of rollers 10 and 10 in directions toward and away from each other. The roller control device 20 reduces the external force applied to the ring R (tension generated in the ring R) by moving the pair of rollers 10 and 10 around which the ring R is wound in a direction close to each other, and is separated from each other. The external force applied to the ring R (tension generated in the ring R) is increased by moving in the direction in which the ring R is moved.
When the inspection of the ring R is performed, the roller control device 20 sets the position of the pair of rollers 10 and 10 to a position where an external force less than the elastic limit is applied to the ring R.

As shown in FIGS. 1 and 2, the light source 30 is a linear light source extending in a predetermined direction, and is a straight portion of the ring R (a portion not curved along the pair of rollers 10 and 10). Light is emitted toward the outer peripheral surface.
The light source 30 is arranged so that the extending direction thereof is inclined with respect to the longitudinal direction (vertical direction in FIG. 2) and the short direction (horizontal direction in FIG. 2) of the ring R.
Therefore, as shown in FIG. 3A, the light emitted from the light source 30 is reflected by the outer peripheral surface of the ring R, and the longitudinal direction of the ring R (vertical direction in FIG. 3A) and the short direction ( A linear light streak L inclined with respect to the left and right direction in FIG. The light source 30 is arranged such that the light streak L extends over both ends of the ring R in the short direction.

As shown in FIG. 1, the imaging device 40 includes a portion illuminated by the light source 30 on the outer peripheral surface of the ring R, that is, a portion where a light streak L (see FIG. 3A) appears on the outer peripheral surface of the ring R. , And an image including the entire image of the light streaks L is acquired.
Since the ring R rotates with the rotation of the pair of rollers 10, 10, the portion illuminated by the light source 30 on the outer peripheral surface of the ring R is imaged continuously or intermittently by the imaging device 40. A plurality of images showing the entire outer peripheral surface will be acquired.

  The analysis device 50 is electrically connected to the imaging device 40, and determines whether or not the cured layer Ra is formed on the surface of the ring R with a uniform thickness by analyzing the image acquired by the imaging device 40. .

As shown in FIG. 3A, in the portion illuminated by the light source 30 in the ring R, when the hardened layer Ra is formed with a uniform thickness, the shape of the light streaks L remains linear. Never do.
On the other hand, as shown in FIG. 3B, in the portion illuminated by the light source 30 in the ring R, when the hardened layer Ra is not formed with a uniform thickness, the shape of the light streaks L changes. In detail, in the part illuminated by the light source 30 in the ring R, the thickness of the cured layer Ra is insufficient (the cured layer Ra is thinner than the other parts, or the cured layer Ra is not formed at all). Is present, the light streak L is distorted at the defective portion.
FIG. 3B shows a case where a defective portion exists in the center of the portion illuminated by the light source 30 in the ring R.

A mechanism in which the light streak L is distorted at the defective portion of the ring R will be described.
As shown in FIG. 4A, when there is no defective portion in the ring R, that is, when the hardened layer Ra is formed with a uniform thickness on the surface (outer peripheral surface and inner peripheral surface) of the ring R, When the roller controller 20 applies an external force to the ring R by moving the pair of rollers 10 and 10 to a predetermined position, a stress in the direction in which the ring R extends is applied to a portion on the inner peripheral surface side of the ring R. As a result, a stress in a direction in which the ring R contracts is generated at a portion on the outer peripheral surface side of the ring R, and the ring R is elastically deformed uniformly.
On the other hand, as shown in FIG. 4B, when there is a defective portion in the ring R on which the hardened layer Ra is formed on the surface (outer peripheral surface and inner peripheral surface), the roller control device 20 includes the pair of rollers 10. When the external force is applied to the ring R by moving 10 to a predetermined position, the ring R extends to the inner peripheral surface side of the ring R, as in the case where no defective portion exists in the ring R. A stress in the direction is generated, and a stress in a direction in which the ring R contracts occurs in a portion on the outer peripheral surface side of the ring R, but the stress is concentrated on the defective portion, and the ring R is elastically deformed unevenly. In other words, in the ring R, the cured layer Ra and the base material Rb have different elastic moduli, so that a defective portion having a thickness different from that of the other portion undergoes elastic deformation different from that of the other portion.
FIG. 4B shows a case where there is a defective portion where no hardened layer Ra is formed on the outer peripheral surface of the ring R.

As described above, the defective portion of the ring R undergoes elastic deformation different from that of the other portions. Therefore, when the outer peripheral surface of the ring R is illuminated by the light source 30, the light from the light source 30 is the other portion. Reflects in a manner different from that of the part. As a result, the light streak L is distorted at the defective portion.
However, when the light source 30 is arranged so that the light streak L extends along the short direction of the ring R, the light streak L is distorted even if the light from the light source 30 is reflected by a defective portion. Therefore, it is necessary to arrange the light source 30 so that the light stripe L is inclined with respect to the short direction.
Further, when the light source 30 is arranged so that the light streaks L extend along the longitudinal direction of the ring R, the entire outer peripheral surface of the ring R cannot be illuminated by the light source 30 as the ring R rotates. Therefore, it is necessary to arrange the light source 30 so that the light streaks L are inclined with respect to the longitudinal direction, in other words, the light streaks L extend across both ends of the ring R in the short direction.

When the analysis device 50 performs predetermined image processing (for example, binarization and edge detection) on the image acquired by the imaging device 40 and detects distortion of the light streaks L in the image, It is determined that a defective portion exists at a position where the light stripe L in the ring R is distorted.
Further, when the distortion of the light streak L is detected, the analysis device 50 calculates the size of the defective portion based on the shape and size of the distortion.

The inspection apparatus 1 configured as described above inspects whether or not the cured layer Ra is formed on the surface of the ring R with a uniform thickness by performing the following steps.
First, the roller control device 20 moves the pair of rollers 10 and 10 to a position where an external force equal to or less than the elastic limit is applied to the ring R, and rotates the ring R by rotating in the same direction.
Next, the light source 30 irradiates light toward the outer peripheral surface of the ring R so that linear light streaks L inclined with respect to the longitudinal direction and the short direction of the ring R appear on the outer peripheral surface of the ring R. To do.
Then, the imaging device 40 captures a portion of the outer peripheral surface of the ring R where the light streaks L appear multiple times, and acquires a plurality of images including the entire image of the light streaks L.
Finally, when the analysis device 50 performs predetermined image processing on each image acquired by the imaging device 40 and detects distortion of the light streak L, the light streak L in the ring R is distorted. It is determined that a defective portion exists at the position.

As described above, the inspection apparatus 1 detects a defective portion based on the shape of the light streaks L appearing on the outer peripheral surface of the ring R without directly detecting the defective portion from the state of the outer peripheral surface of the ring R. Therefore, it is advantageous in terms of excellent robustness.
Furthermore, since dirt adhering to the outer peripheral surface of the ring R does not change the shape of the light streaks L, it is advantageous in that it can suppress erroneous detection such as detecting a portion other than the defective portion of the ring R.
That is, according to the inspection apparatus 1, it is possible to accurately inspect whether or not the cured layer Ra is formed on the surface of the ring R with a uniform thickness.

In addition, when the inspection device 1 inspects the ring R, the external force applied to the ring R is equal to or less than the elastic limit, so that the ring R is not deformed or damaged. That is, since the inspection of the ring R by the inspection device 1 is a nondestructive inspection, the ring R can be shipped as a product after the inspection. Therefore, it is not necessary to discard the ring R used for the inspection, and the cost required for the inspection of the ring R can be reduced.
Further, in the inspection device 1, since the ring R is wound around the pair of rollers 10 and 10 and the pair of rollers 10 and 10 are moved by the roller control device 20, an external force is applied to the ring R. Various sizes of rings R can be accommodated.

In the present embodiment, the annular ring R is inspected by the inspection device 1. However, according to the present invention, the metal that reflects the light emitted from the light source and appears as a light streak on the outer peripheral surface. Any sheet metal plate can be inspected as long as it is a plate.
For example, when inspecting a sheet-like metal plate extending in a predetermined direction, the metal plate is conveyed while applying an external force by a plurality of rollers, and the outer peripheral surface of the metal plate is the same as the inspection device 1. The defective portion of the metal plate may be detected based on the shape of the streaks of light appearing on the surface.

  In the present embodiment, the imaging device 40 and the analysis device 50 are used to determine the presence or absence of a defective portion of the ring R. However, the operator can visually check without using the imaging device 40 and the analysis device 50. It is also possible to determine the presence or absence of a defective portion of the ring R by checking the distortion of the light streak L.

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 10 Roller 20 Roller control apparatus 30 Light source 40 Imaging apparatus 50 Analysis apparatus R Ring (metal plate)
Ra Hardened layer Rb Base material L Light streaks

Claims (2)

An inspection method for inspecting a cured layer formed on the surface of a sheet-like metal plate,
A step of moving the metal plate along the longitudinal direction while applying an external force below the elastic limit to the metal plate;
Irradiating light toward the surface of the metal plate such that linear light streaks inclined with respect to the longitudinal direction and the short direction of the metal plate appear on the surface of the metal plate;
When the light streak is not distorted, it is determined that there is no defective portion with insufficient thickness of the hardened layer in the portion of the metal plate where the light streak is located. Determining that there is a defective part with insufficient thickness of the hardened layer at a position where the streaks of light in the metal plate are distorted when distortion occurs.
Inspection method characterized by that. An inspection device for inspecting a hardened layer formed on the surface of a sheet-like metal plate,
A plurality of rollers for moving the metal plate along the longitudinal direction while applying an external force below the elastic limit to the metal plate;
A light source that emits light toward the surface of the metal plate such that linear light streaks inclined with respect to the longitudinal direction and the short direction of the metal plate appear on the surface of the metal plate;
An imaging device that captures an image of a portion of the surface of the metal plate illuminated by the light source and acquires an image including the light streaks;
In the image, when the light streak is not distorted, it is determined that there is no defective part in which the thickness of the hardened layer is insufficient in the part where the light streak is located in the metal plate, An analysis device that determines that there is a defective portion with insufficient thickness of the hardened layer at a position where the light streak in the metal plate is distorted when the light streak is distorted,
Inspection apparatus characterized by that.

Images