JPH04127010A - Inspection system of the ball of a bearing and its method of inspection - Google Patents

Abstract

PURPOSE: To check each ball for conformability to a standard by turning a plurality of balls, forming the image of each ball, projecting the image to an array of photodetectors and then evaluating the image to detect an incompelte part. CONSTITUTION: Balls 15 arranged in a cassette 16 are scanned one by one with a coherent beam 12 projected through a deflector 11 and the slit 14 in a diffuser 13 and a resultant image is formed on a CCD 17 through a lens 16. When the balls 15 are arranged in a row in the cassette 16, the balls 15 in the cassette 16 are turned and scanned. The image of each ball is formed and projected to an array of photodetectors and then the image is evaluated and an incomplete part is detected thus deciding whether each ball is conformable to a standard or not.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a system and method for inspecting and automatically detecting defects such as imperfections, scratches, etc. in balls of the type used in ball bearings. This method involves rotating the sphere to gradually expose the entire sphere, illuminating the sphere with a coherent beam of light, and projecting an enlarged image of the sphere onto a light-sensitive means, thereby ensuring that each sphere conforms to the standard. This is to determine whether or not the [0002]

[Prior art]

With the miniaturization of systems, the demand for miniature bearings in graduation fields is increasing. In particular, the demand is increasing as the use of personal computers, video equipment, and modern computerized office equipment expands. Here, a miniature bearing is defined as one in which the diameter of the balls is 3 mm or less. [0003] In these types of systems, the miniature bearings are
Operating at extremely low noise and vibration levels is essential, and is of critical importance for recording and computer systems where noise may interfere with the operation of the system. [0004] One major cause of bearing noise is the presence of, for example, scratches, large pits, corrosion, etc. on either the ball surface or the laser surface. [0005]

[Problem to be solved by the invention]

Therefore, quality control and inspection methods are needed to remove defective ("noisy") bearings from the production line. Quality control is performed on balls and races before they are assembled into bearings, and on assembled bearings. Economically, the best way to eliminate defects is to fully inspect balls and races before assembly. [0006]

[Means to solve the problem]

The present invention provides on-line testing of miniature balls of the type used in ball bearings (i.e., typically 0.1 mm to 3 mm in diameter), which may be made of metal, ceramics, or other materials. Regarding how to. The purpose is to eliminate balls that do not meet the standards. This new system is intended to replace traditional inspection methods, which typically use a microscope to perform a tedious visual inspection of such balls to pick out defective balls. Traditional methods tend to be costly, fatigue the person performing such visual inspections, and result in poor quality inspections. In a given manufacturing plant, such balls are produced in large quantities - millions of balls per day. [0007] The novel electro-optical system of the present invention automatically inspects multiple balls, automatically evaluates master craftsmanship, and eliminates defective balls. The system of the present invention rotates the ball in such a way that gradually exposes the entire surface (the area adjacent to the virtuoso's "equator" is scanned), and the virtuoso is optically scanned by a coherent light beam. Means are provided for projecting the magnified image onto a photosensitive means, such as a CCD, and means for evaluating each image for completeness of the scanned ball. [0008] The system includes a novel device for rotating balls, the device being disposed within a means for holding balls arranged in one or more rows and sequentially covering the entire surface of the balls. , it is desirable to expose it. [0009]

【Example】

Embodiments of the invention will now be described with reference to the accompanying drawings, which are not exactly to scale. [0010] As shown in FIG. 1, the electro-optic system includes an acousto-optic deflection plate 11, and a coherent laser beam 12 is transmitted through the deflection plate 11 and passes through a slit 14 to a diffuser 13. As usual, this beam scans the balls 15 placed in the cassette 16 one by one, and the result is imaged through the lens 16 on a CCD 17 connected to an amplifier and evaluation means (not shown). [0011] As explained with reference to FIG.
1, the mechanism for rotating these balls comprises a rotating plate 22 having a vertical axis of rotation, which is connected to a structure 23 by means of a belt 24 rotating in the direction of arrow 25. It is attached. Ball 2 in cassette 21
6 contacts the surface of the belt 24, and the good balls 26 are separated from adjacent balls 26 by a separation wall. The belt 24 and the rotary plate 22 rotate below the groove in which the ball is accommodated, thereby applying a predetermined impact force in the X and Y directions, and this force gradually exposes the entire surface of the ball 26. While the ball 26 rotates, it is scanned as described with respect to FIG. [0012] The system also includes a defect detection algorithm, although any suitable defect detection means may be used. [0013] Even the smallest scratches can be easily detected, with approximately 0.
It is possible to scan balls with diameters as small as about 1 mm and up to 3 mm. Testing is rapid and highly efficient, which improves quality control in terms of production volume and reliability. [0014] Actually, from experiments, for example, in the case of a ball with a diameter of 1 mm, 2 μm
It has been found that defects of about 2 μm or smaller can be detected. Coherent light, preferably a laser beam, is used and this beam is transmitted through an acousto-optic deflection plate, which causes about 20 to 50 pieces to be placed in a row separated from each other in a cassette. , a ball rotated by suitable mechanical means is scanned at a speed such as 2.5 KHz. The ball uses light reflected from the good ball to form an image on the photosensitive means. The image is reflected onto a diffuser, and a convex lens projects the magnified image onto a row of optical sensors forming a CCD matrix or the like. The electrical output is amplified and evaluated. 1S 4-127010 (6) [0015] When a ball with a reflective surface is irradiated with a parallel laser beam, an image is formed at a distance "d" from the ball at a magnification of 20 d/a. Here "a" is the radius of the ball, so the good ball acts as its own magnifying means. [0016] Various algorithms can be used. 50 balls
It is possible to use a parallel detector matrix of 5×5 pixels checking an area of 50 μm. [0017] Each portion of the area is checked in a somewhat consistent manner. A predetermined number of adjacent dark pixels (usually three) indicates a defect that requires the ball to be eliminated. [0018] A mechanical system applies different amounts of force vectors in both the X and Y directions to the ball, which gradually causes it to rotate to expose the entire surface of the ball. [0019] As illustrated in FIG. 3, another mechanical actuation system includes:
A fixed frame 3 which defines a -C compartment 21 for a good ball 33 is provided. 10 when the belt 34 is in contact with the ball
The ball is moved in the direction of arrow 35 below the ball at a speed of the order of 0 mm/sec or less, and at the same time the entire structure is moved in steps in approximately 50 μm increments. The combination of the two vectors will result in the desired rotation of the ball being tested as described above. [0020] As shown in FIG. 4, the device includes a cassette 41 that houses the balls in a fixed frame 42 and a belt 43 that moves below the balls in contact with the balls and between each pair of balls. A plurality of belts 44 are provided perpendicular to the lower belt, these belts 44 moving in the direction of arrow 45. Linear speed in the slow range of 100mm/s and upper belt 1.6m
A linear velocity of m/s gave the ball a proper rotational motion. A detector with an effective frequency of 50 KHz was used in this experiment and very satisfactory signal-to-noise ratios were obtained. For the systems of FIGS. 1 and 2, the signal-to-noise ratio was approximately 2000. [0021]

【effect】

According to the present invention, balls can be inspected very accurately as described above.

[Brief explanation of the drawing]

[FIG. 3] A perspective view showing the optical principle of scanning balls arranged linearly in a Kokushi cassette. FIG. 2 shows a system for rotating the ball during testing.

[Figure 3] FIG. 3 shows another system for rotating the ball.

[Figure 4] FIG. 6 shows yet another system for rotating the ball.

[Explanation of symbols]

11 Acousto-optic deflection plate 12 Laser beam 13 Diffuser 14 Sleeve 15 balls 16 Cassette 17 CCD 21 Cassette 22 Rotating plate 23 Structure 24 Belt 26 balls

【Document name】

drawing

[Figure 1]

[Figure 2]

[Figure 4]

Claims (1)

[Scope of Claims] [Claim 1] A system for automatically inspecting and grading balls, comprising means for holding a plurality of balls of a predetermined shape, mechanically rotating said balls, and a surface of each ball. means for gradually exposing the surface of the ball; means for scanning the surface with a beam of light; means for forming an image of each ball and projecting the image onto a row of photodetectors; and means for evaluating the image to detect the surface of the ball. and means for detecting an imperfect part of the ball and eliminating the imperfect ball. 2. The system according to claim 1, wherein the light is a coherent laser beam, the balls are arranged in a row, and a partition plate is provided between adjacent balls. 3. The system of claim 1, wherein the balls are irradiated with a laser beam through an electro-optical deflection plate, the balls are scanned through a slit in a diffuser, and an image of each ball is reflected onto the diffuser; A system characterized by forming an enlarged image on an array of optical sensors through a lens. [Claim 4
10. The system of claim 3, wherein the sensor array is a CCD system. 5. The system according to claim 1, wherein the balls are located in a cassette, and the balls are activated by a rotary table and, at the same time, by a belt passing below the cassette. system. 6. The system according to claim 1, wherein the balls are extremely small balls. 7. A method for inspecting very small balls, comprising: applying accelerations in the X and Y axes to said balls housed in a housing providing separate compartments for each ball; a stage of gradual exposure;
scanning said surface with a coherent parallel beam of light; forming a magnified image of the surface of each ball on a photosensitive means; and evaluating each ball for the presence of imperfections. A method characterized by: