JP2009258033A - Automatic sphere inspection method and device with ultrasonic flaw detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve inspection precision and reliability of products by stably detecting a sphere surface defect and a sphere internal defect that influence the lifetime of bearings. <P>SOLUTION: In an inspection for a sphere surface defect and a sphere internal defect, a sphere 31 to be inspected is rotated meridian linear in a liquid by a rotary device; ultrasonic waves are transmitted from an ultrasonic probe 36 arranged at a predetermined location opposed to the sphere 31 to be inspected; the ultrasonic waves respectively returned are electrically converted after receiving ultrasonic waves propagate on the sphere surface along the surface of the sphere 31 to be inspected are reflected and returned and ultrasonic waves propagate to a sphere interior on the sphere surface are reflected and returned; and thus waveform signals are obtained and the presence of the sphere surface and the sphere internal defect is determined by the signal level. In advance of the inspection, it is preferred to clean the sphere to be inspected. After the inspection, the sphere is classified to a quality product or a defective product based on the inspection result. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to ball surface defects generated during processing of steel balls, ceramic balls and glass balls used for bearings, ball screws, linear guides, constant velocity joints, ball valves and optical lenses, and material defects generated inside the balls. (Ultrasonic flaw detection sphere automatic inspection method using ultrasonic waves to detect defects such as oxide inclusions in steel, metal inclusions in ceramic balls, segregation of bores and sintering aids) It relates to an apparatus for carrying out the method.

  Conventionally, as shown in FIG. 5, a steel ball appearance inspection device applies light from a filament of a light source 12 to an inspection target ball 11 and receives light reflected from the ball by a light receiving element 13 to electrically convert a change in received light amount. An optical inspection method is known in which a determination unit 14 determines the presence / absence of a defect based on a change amount of an electric signal after being converted into a change in voltage or current (see, for example, Patent Document 1). For internal defect inspection, eddy current inspection and inspection methods using X-rays are also known.

However, in the case of the optical inspection method as described above, in a steel ball having a mirror-like surface used for a general bearing, defects such as oxide inclusions generated at the time of manufacturing the material existing on the surface Defects that occur during processing into a sphere can be detected, but for example, defects that occur during material production do not appear on the surface of the sphere and are present inside the sphere. It is impossible in principle to inspect the inside. There is a concern that defects such as oxide inclusions generated during the production of materials existing inside the sphere have a great influence on the bearing life when the sphere is used in a bearing or the like. For this reason, eddy current flaw detection and inspection methods using X-rays are generally considered, but in the case of eddy current flaw detection, it is possible to detect not only the surface but also defects near the surface. Therefore, it is difficult to detect minute defects that are not exposed on the surface and are completely present inside. In addition, in the inspection method using X-rays, in general, when manufacturing a sphere, it is processed in lot units, the number of lots is from tens of thousands to hundreds of thousands, inspection tact can not be ignored, manual If the inspection is performed, there is a problem that a great labor cost and a processing time are required. On the other hand, a method and an apparatus using ultrasonic waves have been proposed as being capable of quickly detecting minute defects existing on the rolling surface of the rolling element for bearing and in the vicinity of the surface. (For example, see Patent Document 2)
In this method or apparatus, a rolling element for bearing and an ultrasonic probe are disposed in an ultrasonic transmission medium, and the ultrasonic wave is transmitted from the probe while being rotatably held by a rolling means such as a pump. In this method, defects are detected by reflected ultrasonic echoes, and it is disclosed that minute defects existing on the surface of a rolling element and in the vicinity of the surface can be detected.

In addition, as a general ultrasonic detection device, although not a sphere, an ultrasonic wave is transmitted from an ultrasonic wave transmission unit in a state where an inspection object is submerged in a liquid, and an ultrasonic wave transmitted from the transmission unit It is also known to perform inspection by receiving the reflected wave. (For example, see Patent Document 3)
JP 2002-277226 A Japanese Patent Publication No. 5-84865 JP 2007-47056 A

  However, even in the inspection of the sphere using the ultrasonic wave, it is possible to detect defects on the surface of the sphere or in the vicinity of the surface of the sphere. However, the detection of defects such as inclusions produced during the production of the material existing inside the sphere was not sufficient, and when used in a bearing or the like, the influence on the bearing life was inevitable. In particular, it is difficult to manage and control the liquid by rotating the inspection target sphere with an injection means such as a pump, and there is no guarantee that the inspection target sphere is reliably rotating in a meridian shape.

  In view of the actual situation as described above, the present invention copes with this, and the maximum shear stress in the sphere generated when an external load equivalent to the dynamic load rating is applied to the ball bearing as well as the ball surface defect affecting the bearing and the like. Reliable detection at any sphere diameter for inspection of defects inside the sphere from the sphere surface to 3.5% of the sphere diameter, which is about twice as deep as the generation position (approximately 1.5 to 1.75% of the sphere diameter). As a result of finding an ultrasonic method, the defects on the sphere surface and inside can be detected more easily and reliably than in optical inspection to increase the reliability of the product, and a device that sorts non-defective and defective products according to the sphere cleaning device and inspection results. The purpose is to improve the workability by facilitating the coupling.

  That is, the feature of the present invention that meets the above-described object is that an ultrasonic probe is arranged in a predetermined position opposite to the inspection object sphere by rotating the inspection object sphere in a meridian by a rotating device in the liquid. Transmits ultrasonic waves to the inspection target sphere, and ultrasonic waves propagating along the surface of the sphere along the surface of the inspection target sphere are reflected and returned, and ultrasonic waves propagating inside the sphere are reflected back. Ultrasonic flaw detection sphere automatic, characterized by receiving ultrasonic waves, electrically converting each returned ultrasonic wave, obtaining a waveform signal, and determining the presence or absence of defects on the entire surface of the sphere and the inside based on the level of the signal In the inspection method. According to a second aspect of the present invention, the inspection target sphere is washed prior to the inspection to improve the cleanliness.

  A third aspect of the present invention is a process for a sphere that has been subjected to the above-described inspection, and after the inspection has been completed, the discharged sphere is automatically assigned to a non-defective product and a defective product, and a new inspection target sphere is placed in the inspection unit. And

  Claim 4 is an inspection apparatus for carrying out the above inspection method, comprising a drive roller, a support roller immersed in a liquid, a control roller having an eccentric helical gear attached thereto, and giving a twist to the ball to be inspected by the rotation of the control roller, An apparatus for rotating and holding in a meridian shape, an ultrasonic probe arranged at a predetermined position in the liquid facing the inspection object ball held in the liquid by the apparatus, and an ultrasonic probe The transmitted ultrasonic waves are reflected by the surface and inner surface of the inspection target sphere, and the ultrasonic waves that are returned are received and electrically converted to process the signals, and the liquid in which the ultrasonic probe is immersed is purified. It is characterized by a configuration comprising an in-liquid purification device.

  By utilizing the ultrasonic flaw detection automatic sphere inspection method of the present invention, the surface of the sphere and the sphere surface having a depth approximately twice the maximum shear stress generation position inside the sphere can be reduced to 3.5% of the sphere diameter. It is possible to stably detect internal defects, particularly 30 μm or more, and in particular, the entire surface of the sphere as well as the entire surface of the sphere, in combination with scanning the entire surface of the sphere in a meridian, sequentially by the rotating device. The internal automatic inspection is performed more reliably, and the reliability of the product is improved compared to the conventional method, and the labor cost and processing time are greatly reduced compared with the manual inspection, and the workability is also improved. it can.

  Hereinafter, specific embodiments of the present invention will be described. FIG. 1 is an overall schematic diagram showing one mode of an inspection apparatus for carrying out the present invention, and FIG. 2 is a schematic diagram showing a main part of the inspection apparatus constituting the main part of the present invention.

  As shown in FIG. 1, an inspection apparatus for carrying out the inspection of the present invention includes a supply apparatus 1 for supplying an inspection object sphere, a cleaning apparatus 2 including an automatic brush cleaning apparatus for cleaning the supplied inspection object sphere before the inspection, and immersion in a liquid. The inspection unit 3 having the rotation mechanism is sequentially arranged, and the whole is assembled by combining the submerged purification device 4 for purifying the liquid of the inspection unit 3 and the receiving box 5 for receiving the ball after the inspection is completed. Except for the inspection method in the inspection unit 3 to be described later, this arrangement configuration has been described in detail in Japanese Patent Application Laid-Open No. 2002-277226 related to the applicant's application. Is omitted, and the configuration of the inspection unit, which is a feature of the present invention, will be described below with reference to FIG.

  FIG. 2 shows an example of the configuration of the inspection unit constituting the main part of the present invention. In the figure, reference numeral 31 indicates a sphere to be inspected, and the sphere 31 includes a drive roller 32, a support roller 33 and a control which are immersed in the liquid. The roller 34 is held at a predetermined position. An eccentric helical gear 35 is attached to the control roller 34. By rotating the drive roller 32, the inspection target ball 31 rotates and thereby the control roller 34 also rotates. At this time, the control roller 34 is attached to the control roller 34. A twist is given to the inspection object sphere 31 by the eccentric helical gear 35, and the inspection object sphere 31 rotates in a meridian shape.

  In the figure, reference numeral 36 denotes an ultrasonic probe which is an important element in the ultrasonic system inspection of the present invention. The ultrasonic probe is opposed to the inspection target sphere 31 rotating in a meridian by the series of rotating devices and is predetermined in the liquid. The ultrasonic waves are transmitted to the sphere surface of the sphere 31 to be inspected which is arranged at the position and is rotating in a meridian manner.

  The ultrasonic wave transmitted from the ultrasonic probe 36 travels straight to the opposing inspection object sphere 31, is regularly reflected on the surface of the inspection object sphere 31, and returns to the ultrasonic probe 36. Ultrasonic waves propagating along the surface of the sphere, and ultrasonic waves propagating inside the sphere on the surface of the sphere 31 to be inspected. If there is a defect on the sphere surface at the time of manufacturing the sphere, the ultrasonic wave is reflected on the defect portion by the ultrasonic wave propagating along the surface of the sphere 31 to be inspected, and follows the same path. Return to the acoustic probe.

  In addition, when there is a material defect in the sphere during material production, the ultrasonic wave is reflected on the surface of the inspection target sphere 31 by the ultrasonic wave propagating inside the sphere and follows the same path to detect the ultrasonic wave. Return to the tentacles. The returned ultrasonic waves are electrically converted by the converter 40 to obtain a signal as a waveform. By determining the level of the signal, the presence or absence of surface defects and internal defects can be determined.

  In addition, after the inspection is completed, the support roller 33 holding the sphere is operated and the sphere is discharged from the inspection section, and a discrimination gate 37 for distributing the non-defective product and the defective product is installed in the discharged portion. The discrimination gate 37 is activated according to the inspection result, and is automatically assigned to a non-defective product or a defective product. On the other hand, when the sphere is discharged, the rectifying finger 38 moves up and down, so that only one next sphere 39 waiting is put into the inspection section, and the inspection can be continuously performed by repeating this operation.

  As the ultrasonic flaw detection method, when the diameter of the sphere to be inspected is 5.5 mm or less, the maximum shear stress generation position of the sphere can be obtained by using the surface wave method to propagate the ultrasonic wave near the surface to detect defects. It is possible to detect internal defects from the surface of the sphere having a depth about twice that of the sphere to 3.5% (about 0.2 mm) of the sphere diameter. In addition, when the sphere diameter of the sphere to be inspected is larger than 5.5 mm, the surface wave method alone allows the depth from the sphere surface to be about twice the maximum shear stress generation position of the sphere to 3.5% of the sphere diameter. Since it is difficult to detect internal defects, internal inspection from the surface of the sphere, which has a depth of about twice the maximum shear stress position of the sphere, to the inside of the sphere diameter of 3.5% by combining oblique angle inspection and vertical inspection. It is possible to detect defects.

  Here, the ultrasonic probe 36 to be used depends on the sphere diameter and material of the sphere to be inspected. For example, in order to inspect a steel sphere having a sphere diameter of about 10 mm, the frequency is 5 to 20 MHz and the element diameter is 6 mm. The degree is preferable in terms of inspection capability. When inspecting ceramic spheres, it is preferable in terms of inspection capability to use an ultrasonic probe having a higher frequency (30 to 100 MHz) than when inspecting steel balls. Moreover, the jig to which the ultrasonic probe is attached has a structure that can be easily adjusted in the vertical and horizontal directions, and can transmit ultrasonic waves to any location of the sphere.

  Note that the liquid in which the rotating device and the ultrasonic probe are immersed is purified by the in-liquid purification device to remove fines and bubbles such as dust and dirt in the liquid. The inspection accuracy is improved by preventing the deterioration of the yield due to the pseudo defect signal due to the minute objects and bubbles. Further, as the liquid used here, not only oil but also water can be used, but oil is used in the present invention in consideration of rusting of the machine. Next, examples of the inspection will be described.

  Using the above apparatus, a sphere having a sphere diameter of 10 mm was rotated in a meridian manner by rotation of a drive roller, a support roller, and a control roller, and ultrasonic waves were transmitted from the ultrasonic probe to the sphere surface. When the transmitted ultrasonic wave is propagated to the surface of the sphere and returned to the inside of the sphere, the ultrasonic wave is received and confirmed by the waveform signal, and the waveform as shown in FIG. Although it was recognized, a sphere determined to be NG was confirmed by ultrasonic flaw detection. As a result, a signal considered to be a defect as shown in FIG. Therefore, when the surface of the sphere in which a signal that seems to be a defect was confirmed was confirmed with a microscope, defects that occurred during processing on the surface of the sphere were confirmed. In addition, even if the sphere was confirmed to have a defect, the sphere whose defect was not confirmed on the surface of the sphere was confirmed by a microscope each time it was cut from the sphere surface by several μm. In FIG. 4, defects of several tens of μm of oxide inclusions were confirmed. In addition, as for the sphere in which a signal that seems to be a defect was not seen as shown in FIG. 3 (a), the defect was not confirmed although the surface of the sphere was similarly confirmed and the microscope was confirmed each time the sphere surface was cut by several μm. It was. Therefore, it was confirmed that the entire surface of the sphere and the inside of the sphere can be automatically inspected by the ultrasonic flaw inspection of the present invention.

It is a figure showing roughly the present invention inspection device whole. It is a figure which shows roughly the test | inspection part which makes the principal part of this invention test | inspection apparatus. The signal waveform at the time of utilizing the ultrasonic wave by this invention is shown, (A) is a case without a defect, (B) is a case with a defect. It is a microscope picture of a typical defect detected by the present invention. It is a figure which shows the outline | summary of the conventional inspection apparatus.

Explanation of symbols

1: Supply device 2: Cleaning device 3: Submerged purification device 5: Receiving box 31: Ball to be inspected 32: Drive roller 33: Support roller 34: Control roller 35: Eccentric helical gear 36: Ultrasonic probe 37: Discrimination gate 38: Commutation finger 39: Standby ball 40: Converter

Claims (4)

  The inspection target sphere is rotated in a meridian by a rotating device in the liquid, and ultrasonic waves are transmitted to the inspection target sphere from the ultrasonic probe arranged at a predetermined position facing the inspection target sphere. The ultrasonic waves propagating along the surface of the sphere are reflected and returned, and the ultrasonic waves propagating from the sphere surface to the inside of the sphere are reflected and returned. An ultrasonic flaw detection type sphere automatic inspection method characterized by obtaining a waveform signal by electrical conversion and determining the presence or absence of a defect on the sphere surface and inside the sphere based on the level of the signal.   2. The ultrasonic flaw detection type sphere automatic inspection method according to claim 1, wherein the inspection target sphere is cleaned prior to the inspection to improve cleanliness.   3. The ultrasonic flaw detection type ball automatic inspection method according to claim 1 or 2, wherein after the inspection is completed, the discharged balls are automatically distributed to a non-defective product and a defective product, and a new inspection target ball is thrown into the inspection unit.   A device comprising a drive roller, a support roller immersed in the liquid, and a control roller having an eccentric helical gear attached thereto, a device that twists the sphere to be inspected by rotation of the control roller and holds it in a meridian shape, The ultrasonic probe arranged at a predetermined position in the liquid opposite to the inspection target sphere supported by, and the ultrasonic wave transmitted from the ultrasonic probe are reflected by the surface and the inner surface of the inspection target sphere. An ultrasonic system sphere comprising: a signal processing unit that receives and electrically converts a returned ultrasonic wave to process a signal; and an in-liquid purification device that purifies the liquid in which the ultrasonic probe is immersed. Automatic inspection device.