JP7573861B2 - Quality inspection method and quality inspection device used therein - Google Patents

Description

The present invention relates to a quality inspection method for inspecting the quality of a grinding wheel used to grind an object.

There are quality inspection methods for inspecting the quality of grinding wheels used to polish objects. For example, the resonant frequency measurement method (sonic method) is known as such a quality inspection method (see, for example, non-patent documents 1 to 3). In addition, there are other prior art documents related to the present invention, such as non-patent documents 4 to 6.

T. E. Dustine, Electronics, 24, 4 (1951) 115 R. G. Rowe, Steel, 126, 26 (1950) 74 Abrasive Processing Research Association, Abrasive Processing Technology Handbook, Japan, (1965) 947 Kuniaki Umino, Takashi Shinozaki, Study on the measurement of the bond strength of grinding wheels (1st report), Seimitsu Kikai, Japan, 36, 8 (1970) 538 Kuniaki Umino, Takashi Shinozaki, Study on the measurement of the bond strength of grinding wheels (2nd report), Seimitsu Kikai, Japan, 36, 9 (1970) 608 Kuniaki Umino, Takashi Shinozaki, Evaluation of the degree of bonding of fine-grained grinding wheels - Study on the degree of bonding of grinding wheels (3rd report) -, Seimitsu Kikai, Japan, 38, 1 (1972) 161

Grinding of structural materials for aircraft and automobiles and next-generation power device materials for semiconductors is becoming more difficult. On the other hand, increasing demand and strengthening international competitiveness require improving processing efficiency, reducing processing costs, and achieving high-quality, high-precision processing, which are major issues for production sites. In this context, it is desirable to transition from ordinary grinding wheels such as WA (white alundum) wheels or GC (green carborundum) wheels, which have superior wear resistance and high thermal conductivity, to superabrasive wheels with CBN (cubic boron nitride) or diamond abrasives. However, although superabrasive wheels have been on the market for a long time, they have not been widely used due to the difficulty of truing and dressing, and the unclear relationship between the mechanical properties of the abrasive layer (especially the Young's modulus) and the grinding performance. In addition, the binder and filler (additive) contained in the abrasive layer of superabrasive wheels are the know-how of the manufacturer, and the Young's modulus as a structure of the abrasive layer tends not to be grasped at the production site. For this reason, the controllability of superabrasive wheels is low, and the quality of the processing results often depends mainly on the skill of the operator. For this reason, research and technological development in grinding processes mainly focuses on monitoring or sensing the grinding state, and there is a tendency for little consideration to be given to technologies that predict the processing state and processing results at the pre-processing stage. Similar to the life curve (VT diagram) used as a performance evaluation method for cutting tools, if the mechanical properties of the abrasive layer, including the longitudinal elastic modulus, and the grinding performance (abrasive wear characteristics) of superabrasive wheels can be related, the processing performance can be evaluated from the mechanical properties of the abrasive layer, which provides useful information for wheel selection and setting grinding work conditions.

For example, the resonance frequency measurement method of Non-Patent Document 1 can measure the modulus of longitudinal elasticity of ordinary grinding wheels among various grinding wheels. The modulus of longitudinal elasticity is related to the mechanical properties of the grinding wheel, so it is highly related to its quality and is considered to be one of the indicators of the quality of the grinding wheel. For example, Non-Patent Document 6 discloses the relationship between the modulus of longitudinal elasticity and the grinding performance of the grinding wheel. Therefore, the resonance frequency measurement method of Non-Patent Document 1 can function as one of the quality inspection methods for ordinary grinding wheels. The same is true for the resonance frequency measurement methods disclosed in Non-Patent Documents 2 and 3. Furthermore, Non-Patent Documents 4 and 5 disclose an ultrasonic pulse transmission method, but such an ultrasonic pulse transmission method can also measure the modulus of longitudinal elasticity of the grinding wheel. Therefore, these ultrasonic pulse transmission methods can also function as quality inspection methods for ordinary grinding wheels. However, due to the structure of the superabrasive wheel in which the abrasive layer is fixed to the base metal, it is difficult to apply the sonic method or ultrasonic pulse method applied to ordinary grinding wheels. For this reason, it is believed that there is currently no established method for measuring the longitudinal elastic modulus of the abrasive layer, and there is a need for a method for inspecting the quality of superabrasive wheels that includes measuring the longitudinal elastic modulus.

For example, manufacturers may separately form sticks with the same distribution as the abrasive layer of the superabrasive wheel and inspect the quality of those sticks, and the inspection results may be used as a substitute for the quality inspection of the superabrasive wheel. However, this inspection method only inspects a substitute quality and does not inspect the quality of the superabrasive wheel itself. Also, forming sticks for inspection is time-consuming and labor-intensive.

The present invention aims to provide a quality inspection method that can be applied to the quality inspection of various types of grinding wheels.

The quality inspection method of the present invention is a quality inspection method for inspecting the quality of a grinding wheel for grinding an object, and includes a wave generation step of actually generating surface waves on the grinding wheel through a wave generation means (7) for generating surface waves on the grinding wheel, a wave detection step of detecting actual surface waves as surface waves actually generated on the grinding wheel through a detection means (2) for detecting the surface waves of the grinding wheel, and a quality evaluation step of evaluating the quality of the grinding wheel based on the actual surface waves and discrimination information for discriminating the quality of the grinding wheel using the actual surface waves.

According to the present invention, the quality of a grinding wheel is evaluated based on the surface waves generated on the grinding wheel. In other words, surface waves are used to evaluate the quality of the grinding wheel. Surface waves can occur not only on ordinary grinding wheels, but also on the abrasive layer of a superabrasive wheel. Therefore, the quality of not only ordinary grinding wheels, but also the abrasive layer of a superabrasive wheel can be evaluated using surface waves. In other words, the quality of not only ordinary grinding wheels but also superabrasive wheels can be evaluated. As a result, compared to sonic methods, etc., this method can be applied to quality inspection of a variety of grinding wheels. In addition, since the grinding wheel can be evaluated directly, the time and effort required to prepare substitutes can be reduced compared to when quality is evaluated through substitutes, for example.

The surface waves generated on the grinding wheel are related to its quality. For this reason, various components of the surface waves generated on the grinding wheel may be used to evaluate the quality. For example, the propagation speed of the surface waves generated on the grinding wheel may be used to evaluate the quality. Specifically, for example, in one aspect of the quality inspection method of the present invention, the wave detection procedure may be configured to detect the propagation speed of the surface wave as the actual surface wave, and the quality evaluation procedure may be configured to use the propagation speed of the surface wave as the actual surface wave and evaluate the quality of the grinding wheel based on the propagation speed and the discrimination information.

The propagation velocity of the surface wave may be detected appropriately by various methods. For this reason, a detection means according to such various methods may be used, and the wave detection procedure may be configured as a procedure according to such a detection means. For example, the detection means may be configured to directly measure the propagation velocity, and the propagation velocity of the surface wave may be directly detected in the wave detection procedure. Alternatively, the detection means may be configured to indirectly detect the propagation velocity of the surface wave. Specifically, for example, in an aspect in which the propagation speed of surface waves is used for quality inspection, the detection means may include a first detection means (2A) and a second detection means (2B) that respectively detect the actual surface waves at two locations on the grinding wheel spaced a predetermined distance (WD2), and the wave detection procedure may include a first detection procedure for detecting the actual surface waves at the two locations through the first detection means and the second detection means, and a second detection procedure for detecting the propagation speed by calculating the actual surface wave propagation speed based on the time lag between the detection time of the actual surface wave by the first detection means and the detection time of the actual surface wave by the second detection means.

In the quality evaluation procedure, the quality of the grindstone may be appropriately evaluated based on the surface waves. For example, in the quality evaluation procedure, the longitudinal elastic modulus of the grindstone may be calculated based on the propagation velocity of the surface waves as the quality of the grindstone, or an element based on the longitudinal elastic modulus may be provided as the quality. The quality of the grindstone is also reflected in the delay degree of the propagation velocity of the surface waves. For this reason, in the quality evaluation procedure, the delay degree of the propagation velocity of the surface waves may be calculated as the quality of the grindstone, or an element based on the delay degree may be provided as the quality. Specifically, for example, in an aspect in which the propagation velocity of the surface waves is used in quality inspection, the discrimination information may include information on a reference propagation velocity as a propagation velocity that should function as a criterion for discriminating the quality of the grindstone, and the quality evaluation procedure may be configured to evaluate the quality of the grindstone by comparing the propagation velocity of the actual surface waves with the reference propagation velocity. Alternatively, the discrimination information may include information on the Poisson's ratio and density of the grinding wheel, and the quality evaluation procedure may include a first evaluation procedure of calculating the propagation velocity of the shear wave based on equation (1) when the propagation velocity of the actual surface wave is Vp _, the Poisson's ratio is v, and the propagation velocity of the shear wave related to the actual surface wave is Vs _, and a second evaluation procedure of calculating the longitudinal elastic modulus based on equation (2) as an evaluation of the quality of the grinding wheel when the density is ρ and the longitudinal elastic modulus of the grinding wheel is E, respectively.

The quality inspection device of the present invention is a quality inspection device (1) that inspects the quality of a grinding wheel for grinding an object, and includes two elastic wave detection devices (2A, 2B) that are arranged at two locations on the grinding wheel with a predetermined distance (WD2) between them to detect elastic waves when elastic waves are generated on the grinding wheel through a wave generation means (7), a speed calculation means (14) that calculates an actual propagation velocity as the propagation velocity of the actual surface wave based on the delay time between the two locations generated in the actual surface wave as a surface wave detected by each elastic wave inspection device among the elastic waves, and a quality evaluation means (14) that evaluates the quality of the grinding wheel based on the actual propagation velocity and discrimination information for discriminating the quality of the grinding wheel using the actual propagation velocity. The quality inspection device of the present invention can realize the quality inspection method of the present invention.

In the above explanation, reference symbols of the attached drawings are given in parentheses to facilitate understanding of the present invention, but this does not mean that the present invention is limited to the illustrated form.

As described above, the present invention provides a quality inspection method that can be applied to the quality inspection of various types of grinding wheels.

1 is a diagram showing an example of the overall configuration of a quality inspection device applied to a quality inspection method according to an embodiment of the present invention. 1 is a functional block diagram showing a main part of a control system of a quality inspection device applied to a quality inspection method according to an embodiment of the present invention. 1 is an explanatory diagram for explaining a procedure of a quality inspection method according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a configuration of reference data. 11 is a flowchart showing an example of a procedure of a quality evaluation process. FIG. 13 shows the measurement results of the delay time of surface waves at two locations. FIG. 13 is a diagram showing a comparison between theoretical and experimental values of the propagation speed of surface waves in various materials. FIG. 13 is a graph showing the results of measuring surface waves of abrasive grain layers with different grain sizes. FIG. 13 is a graph showing the results of measuring surface waves of abrasive grain layers having different concentrations. FIG. 13 shows the results of measuring surface waves on diamond wheels with different binders. FIG. 1 is a diagram showing the relationship between the type of superabrasive grain and surface waves. FIG. 13 is a graph showing a comparison of the propagation speed of surface waves when there is a defect in the abrasive layer of a wheel and when there is no defect. 13 is a graph showing a comparison of the propagation speed of surface waves when the abrasive grain layer of a wheel similar to the example in FIG. 12 has a defect different from that in the example in FIG. 12 and when the wheel does not have such a defect. A table showing the Poisson's ratio and density values for various materials. FIG. 1 is a diagram showing theoretical and experimental values of the Young's modulus for various materials. 1 is a table showing the Poisson's ratio and density values used in the examples. FIG. 13 is a graph showing the calculated values of the longitudinal elastic modulus in the abrasive layer of a superabrasive wheel.

Hereinafter, one embodiment of the quality inspection method of the present invention will be described. First, referring to FIG. 1, the overall configuration of a quality inspection device applied to a quality inspection method according to one embodiment of the present invention will be described. The quality inspection method of the present invention is a method for inspecting (evaluating) the quality of an object to be inspected based on a surface wave generated on the object to be inspected. In the quality inspection method of the present invention, various components of the surface wave can be used to inspect the quality, but the example of FIG. 1 shows a case in which the propagation speed of the surface wave is used to inspect the quality. Similarly, the propagation speed of the surface wave generated on the object to be inspected may be detected by various methods, but the example of FIG. 1 shows a case in which the propagation speed of the surface wave is detected based on the difference in detection time of the surface wave generated at two different points on the object to be inspected. In this case, as shown in FIG. 1, the quality inspection device 1 includes a sensor (detection device) 2 as a detection means, an amplifier 3, a data recording device (data logger) 4, and a computer device 5.

The quality inspection device 1 may be applied to quality inspection of various objects to be inspected, but in the example of FIG. 1, it is applied to quality inspection of a circular grinding wheel 6. The grinding wheel 6 is used to polish an appropriate object. The grinding wheel 6 may include various grinding wheels such as a WA grinding wheel or a GC grinding wheel, as appropriate, but in the example of FIG. 1, it is configured as a superabrasive wheel using CBN or diamond as abrasive grains. For this reason, the grinding wheel 6 is provided with a superabrasive grain layer 6a.

The surface waves in the grindstone 6 may be generated by any suitable method, for example, through a generator 7 as a wave generating means. The generator 7 is a device for generating surface waves. Various devices capable of generating surface waves may be used as the generator 7, and depending on the configuration, the operation may be controlled by a computer device 5 or the like as part of the quality inspection device 1. In this way, various devices may be used as the generator 7 as appropriate, and as an example, a mechanical pencil is used. A mechanical pencil is a well-known device that can generate surface waves by the mechanical pencil lead compression method (a method standardized as E976 by the American Society for Testing and Materials). In this method, the repeatability can be improved by keeping the angle at which the mechanical pencil lead is compressed constant. The generator (mechanical pencil) 7 may generate surface waves at any suitable position on the grindstone 6, but as an example, it is installed so as to generate surface waves in the superabrasive layer 6a.

The sensor 2 is a device for detecting surface waves generated on the grinding wheel 6. Surface waves may be detected by any suitable method as described above, and the sensor 2 may be configured appropriately in accordance with the method, but in the example of FIG. 1, it includes a first sensor 2A as a first detection means and a second sensor 2B as a second detection means. Any suitable sensor capable of detecting surface waves may be used as the first sensor 2A and the second sensor 2B, but as an example, an AE (acoustic emission) sensor is used. The AE sensor is a well-known sensor (an example of an elastic wave detection device) that detects elastic waves (AE waves).

The first sensor 2A and the second sensor 2B are installed so as to detect surface waves generated at two different locations on the grinding wheel 6. The first sensor 2A and the second sensor 2B (both AE sensors) may be installed at two appropriate locations on the object to be detected (grinding wheel 6). For example, they may be arranged so as to sandwich the superabrasive layer 6a in the depth direction (direction perpendicular to the paper surface) in the example of FIG. 1, but in the example of FIG. 1, they are installed at positions separated in the circumferential direction. Specifically, the first sensor 2A is installed so as to be located a certain distance WD1 away from the position where the generator 7 generates the surface wave. The second sensor 2B is also arranged so as to be located a predetermined distance WD2 away from the first sensor 2A. In other words, the first sensor 2A and the second sensor 2B are installed so as to be separated by a predetermined distance WD2 (for example, a width corresponding to the angle r with respect to the center CN of the grinding wheel) between them.

The amplifier 3 is a device for amplifying the detection result of the sensor 2. The amplifier 3 may be omitted as appropriate, but in the example of FIG. 1, it includes a first amplifier 3A and a second amplifier 3B corresponding to the first sensor 2A and the second sensor 2B, respectively. The first amplifier 3A is used to amplify the detection result of the first sensor 2A, and the second amplifier 3B is used to amplify the detection result of the second sensor 2B. For this reason, the first amplifier 3A and the second amplifier 3B are connected to the first sensor 2A and the second sensor 2B, respectively, so that their detection results can be acquired.

The data recording device 4 is a well-known device that records the amplification results by the amplifier 3. The data recording device 4 may be omitted as appropriate, but in the example of FIG. 1, it is provided to record the amplification results of the first amplifier 3A and the second amplifier 3B. For this reason, the data recording device 4 is connected to the first amplifier 3A and the second amplifier 3B. Furthermore, the data recording device 4 is connected to a computer device 5 so as to provide the recorded amplification results at appropriate times.

The computer device 5 is a well-known device for executing various calculations (processing) based on the detection results of the sensor 2. The computer device 5 may be a desktop or notebook personal computer (hereinafter sometimes referred to as a PC), a mobile terminal device such as a mobile phone (including a smartphone), or a portable tablet terminal device, but in the example of FIG. 1, a desktop PC is used. The computer device 5 executes various processes based on the detection results of the sensor 2, more specifically, the detection results after being amplified by the amplifier 3, and such processes include a quality evaluation of the grinding wheel 6.

Next, referring to FIG. 2, the configuration of the main parts of the control system of the quality inspection device 1 will be described. FIG. 2 is a functional block diagram showing the main parts of the control system of the quality inspection device 1. As shown in FIG. 2, the computer device 5 is provided with a control unit 11 and a storage unit 12. The storage unit 12 is composed of a storage unit including a non-volatile storage medium (computer-readable storage medium) such as a hard disk array. The storage unit 12 stores a program (computer program) PG to be referenced by the control unit 11, and inspection data CD. The inspection data CD may include various data necessary for quality inspection as appropriate, but in the example of FIG. 2, reference data RD is shown. The reference data RD is data in which various information that serves as the basis for quality inspection is described. Details of the reference data RD will be described later.

The control unit 11 is configured using computer hardware resources (e.g., a CPU) of the computer device 5. Various devices provided in the quality inspection device 1 can be appropriately connected to the control unit 11, including the sensor 2, amplifier 3, and data recording device 4 described above. Specifically, the data recording device 4 is directly connected to the control unit 11 so as to provide the detection results recorded therein. Meanwhile, the amplifier 3 is indirectly connected to the control unit 11 via the data recording device 4, and the sensor 2 is indirectly connected to the control unit 11 via the amplifier 3. The sensor 2 includes a first sensor 2A and a second sensor 2B, and the amplifier 3 includes a first amplifier 3A and a second amplifier 3B.

In the control unit 11, various logical devices related to quality inspection can be configured by combining the hardware resources constituting the control unit 11 and the program PG, but in the example of FIG. 2, an equipment control unit 13 and a quality evaluation unit 14 are shown. The equipment control unit 13 is a logical device that performs various processes related to the control of various devices connected to the computer device 5. Such processes include, for example, processes for acquiring appropriate information such as detection results recorded in the data recording device 4. The quality evaluation unit 14 is a logical device that performs various processes related to the evaluation of the quality of the grinding wheel 6. Such processes include various processes for realizing quality evaluation (quality inspection) of the grinding wheel 6 (inspected object). For example, the quality evaluation unit 14 executes a quality evaluation process as one of such processes. The procedure of the quality evaluation process will be described in detail later.

The computer device 5 may be provided with various other output devices and input devices necessary for quality inspection as appropriate, but in the example of FIG. 2, a monitor MO and a keyboard KB are shown as such output devices and input devices, respectively. The monitor MO is a well-known display device that appropriately displays various images related to quality inspection. The keyboard KB is a well-known input device for inputting pressing operations by the user. These are used as appropriate to carry out the quality inspection.

Next, referring to FIG. 3, a procedure for implementing a quality inspection method according to one embodiment of the present invention will be described. FIG. 3 is an explanatory diagram for explaining the procedure of a quality inspection method according to one embodiment of the present invention. As shown in FIG. 3, a quality inspection method according to one embodiment of the present invention includes a wave generation procedure (F1), a wave detection procedure (F2), and a quality evaluation procedure (F3) in that order. The wave generation procedure is a procedure for generating surface waves in an object to be inspected (F1). In the wave generation procedure, the generation of surface waves may be realized by an appropriate method, but in the quality inspection device 1, the generation of surface waves is realized in the grinding wheel 6 as the object to be inspected through the generator 7 as described above. More specifically, in the quality inspection device 1, the wave generation procedure is realized (configured) as a procedure for generating surface waves in the superabrasive layer 6a of the grinding wheel 6 by the mechanical pencil lead compression method through a mechanical pencil as the generator 7.

The wave detection procedure is a procedure for detecting actual surface waves generated on the object to be inspected (F2). In the wave detection procedure, the actual surface waves may be detected by any suitable method, but in the quality inspection device 1, they are detected through the first sensor 2A and the second sensor 2B as described above. In addition, in the quality inspection device 1, the propagation speed of the surface waves actually generated in the superabrasive layer 6a as actual surface waves is detected through the first sensor 2A and the second sensor 2B. Therefore, in the case of the quality inspection device 1, the wave detection procedure includes a first detection procedure for detecting actual surface waves at two different locations through the first sensor 2A and the second sensor 2B, respectively, and a second detection procedure for detecting the propagation speed by calculation based on the delay time of the actual surface waves between those two locations.

Specifically, in the first detection procedure, surface waves occurring at two different locations are detected by the first sensor 2A, which is located at a fixed distance WD1 from the position of the generator 7, and the second sensor 2B, which is located at a predetermined interval WD2 from the position of the generator 7. In addition, since the first sensor 2A and the second sensor 2B are separated by the predetermined interval WD2, there is a difference in the detection time of the surface waves occurring from the position of the generator 7. In other words, there is a difference in the detection time between the first sensor 2A and the second sensor 2B. In the second detection procedure, the propagation speed of the surface waves actually occurring in the superabrasive layer 6a is calculated based on the difference time. More specifically, the propagation speed is calculated by dividing the predetermined interval WD2 (the distance between the two locations) by the difference time. Then, the calculated propagation speed is detected as the propagation speed of the surface waves actually occurring in the superabrasive layer 6a.

The quality evaluation procedure is a procedure (F3) for evaluating the quality of the object to be inspected based on the detection results in the wave detection procedure (F2). The quality of the object to be inspected can be evaluated based on various factors related to the actual surface waves, and in the quality inspection device 1, such factors include the degree of delay in the propagation velocity and the value of the longitudinal elastic modulus. In other words, in the quality inspection device 1, the quality of the grinding wheel 6 is evaluated based on the degree of delay in the propagation velocity and the value of the longitudinal elastic modulus.

For example, the propagation speed of the surface waves shows a tendency related to the quality of the grinding wheel 6. Specifically, the propagation speed of the surface waves shows a tendency to be slower as the degree of concentration is lower (the density of the abrasive grains in the superabrasive grain layer 6a is lower). A similar tendency occurs when there are defects such as cracks. Therefore, the degree of concentration of the grinding wheel 6 or the presence or absence of defects is determined depending on whether the propagation speed of the surface waves is slower than a predetermined reference value (degree of delay). In other words, if the propagation speed of the surface waves is equal to or greater than a predetermined reference value, it is assumed that the degree of concentration is equal to or greater than a certain level and that there are no defects. Therefore, the quality of the grinding wheel 6 is evaluated based on the degree of delay obtained by comparing the propagation speed actually detected in the superabrasive grain layer 6a with a predetermined reference value.

The evaluation of quality by comparing the actually detected propagation velocity with a predetermined reference value may be appropriately performed, for example, by an inspector (person) who stores or refers to the predetermined reference value, but as an example, it is executed by the computer device 5. More specifically, the quality evaluation unit 14 of the computer device 5 performs the evaluation of quality through a quality evaluation process while referring to the reference data RD. As the predetermined reference value, an appropriate value that can serve as a standard, such as a theoretical value for the material to be inspected, an actual measurement value (empirical value) of an object corresponding to a certain quality, or an average value of the measurement results for multiple objects to be inspected, may be used. Therefore, when the quality is evaluated based on the degree of delay in the propagation velocity, such a predetermined reference value is described as a standard in the reference data RD.

On the other hand, the modulus of elasticity is a well-known factor related to the properties of the abrasive layer. The abrasive layer contains various mixtures of additives and the like. For this reason, it tends to be difficult to determine the modulus of elasticity of the abrasive layer at the production site, but knowing the modulus of elasticity leads to an understanding of the quality of the object being inspected. As an example, the modulus of elasticity is calculated based on the following five formulas.

Specifically, elastic waves that propagate through an elastic body include three types: longitudinal waves, transverse waves, and surface waves. When the elastic body is sufficiently large compared to the wavelength and can be considered uniform and isotropic, Rayleigh has shown that the propagation speed of a wave along the free surface of a semi-infinite isotropic body can be derived based on the following equations (A), (B), and (C). Here,
Vp: longitudinal wave propagation speed (min/sec)
Vs: Shear wave propagation speed (min/sec)
Vr: propagation speed of the surface wave (min/sec)
v: Poisson's ratio E: Modulus of elasticity (gigapascal)
ρ: density (kilograms/cubic meter)
G: Shear elastic modulus.

However, these formulas (A) to (C) only apply to the case of a single material. Because the ultrasonic pulse transmission method is used to evaluate the longitudinal elastic modulus of ordinary grinding wheels, which are made up of abrasive grains, binder, and pores, ordinary grinding wheels can be considered to be isotropic. For this reason, formulas (A) to (C) are also thought to be applicable to the abrasive layer of superabrasive wheels.

On the other hand, formulas (A) to (C) have too many variables and are not suitable for calculating the longitudinal elastic modulus. For this reason, when the longitudinal elastic modulus is calculated as the quality of the object being inspected in the quality evaluation procedure, a formula that limits the measurable variables is derived from formulas (A) to (C) and used. For example, formulas (A) and (B) are both formulas related to the longitudinal elastic modulus E. For this reason, based on formulas (A) and (B), the following formula (D) is derived as a formula that does not include the longitudinal elastic modulus E as a variable. Furthermore, by substituting formula (D) for the longitudinal wave propagation velocity Vp in formula (C), the following formula (E) is obtained as a formula that does not include the longitudinal wave propagation velocity Vp as a variable.

Equation (E) is expressed as a polynomial of only the surface wave propagation velocity Vr, the shear wave propagation velocity Vs, and the Poisson's ratio v. In other words, the shear wave propagation velocity Vs is derived by substituting the surface wave propagation velocity Vr actually detected in the elastic body and the Poisson's ratio v of the elastic body into equation (E). Then, the derived (calculated) shear wave propagation velocity Vs and the density ρ of the elastic body are substituted into equation (E) to calculate the longitudinal elastic modulus E of the elastic body. Therefore, in the quality evaluation procedure, the longitudinal elastic modulus E of the superabrasive layer 6a (elastic body) is calculated based on equation (E) and equation (B).

Specifically, when the longitudinal elastic modulus E is calculated as the quality of the grinding wheel 6, the quality evaluation procedure includes a first evaluation procedure for calculating the shear wave propagation velocity Vs based on the formula (E), and a second evaluation procedure for calculating the longitudinal elastic modulus E based on the calculation result and the formula (B). For example, in the first evaluation procedure, the shear wave propagation velocity Vs is calculated by substituting the shear wave propagation velocity Vs detected in the wave detection procedure and the Poisson's ratio v of the superabrasive layer 6a into the formula (E). Similarly, in the second evaluation procedure, the shear wave propagation velocity Vs calculated in the first evaluation procedure and the density ρ of the superabrasive layer 6a are substituting into the formula (B) to calculate the longitudinal elastic modulus E.

The calculation of the shear wave propagation velocity Vs in the first evaluation procedure and the calculation of the longitudinal elastic modulus E in the second evaluation procedure may be performed as appropriate, for example by an inspector, but as an example, both are performed by the computer device 5. More specifically, the quality evaluation unit 14 of the computer device 5 performs the quality evaluation process while referring to the reference data RD, thereby calculating the shear wave propagation velocity Vs or the longitudinal elastic modulus E. For this reason, the Poisson's ratio v and density ρ may be provided as appropriate, or may be provided by the inspector each time, but as an example, they are provided via the reference data RD. In other words, when the longitudinal elastic modulus E is calculated as the quality of the grinding wheel 6, the information on the Poisson's ratio v and density ρ is described as a standard in the reference data RD.

Next, the reference data RD will be described in detail with reference to FIG. 4. FIG. 4 is a diagram showing an example of the configuration of the reference data RD. As shown in FIG. 4, the reference data RD includes a reference record RDR for managing various standards for each test subject. Furthermore, in order to realize such management, the reference record RDR includes information on "subject" and "standard." The reference record RDR records these pieces of information so that they are associated with each other.

"Object" is information that indicates the object being inspected. When there are multiple objects being inspected, various pieces of information that can identify each object being inspected may be appropriately described in "Object" as information indicating the object being inspected. For example, information such as the name and type of object being inspected (super abrasive wheel, etc., which may include information indicating the CBN content and degree of concentration) may be appropriately described, but as an example, a number that is uniquely assigned to each object being inspected may be described.

The "standard" is information indicating various standards necessary to determine the quality of the object to be inspected. Such a standard may include various information as appropriate depending on the quality evaluation method, but for example, when the quality is evaluated based on the degree of delay in the propagation velocity, a predetermined standard value for obtaining the degree of delay (a propagation velocity value that is a standard to be compared with the propagation velocity of the actual surface wave in the quality evaluation procedure) is included. Similarly, when the longitudinal elastic modulus E is calculated as the quality of the object to be inspected, the Poisson's ratio v and density ρ of the object to be inspected are included in the standard information described in the "standard". In this example, the standard information described in the "standard" functions as the discrimination information of the present invention. In addition, the predetermined standard value included in the standard information functions as the reference propagation velocity of the present invention. Note that the standard data RD is not limited to these pieces of information, and may include various pieces of information as appropriate depending on the quality evaluation method, etc. Alternatively, part of the above information may be omitted as appropriate.

Next, the quality evaluation process will be described. The quality evaluation process is a process for evaluating the quality of the object to be inspected through the quality inspection device 1. More specifically, the quality evaluation process is a process for implementing a wave detection procedure and a quality evaluation procedure through the quality inspection device 1. FIG. 5 is a flowchart showing an example of the quality evaluation process. The example of FIG. 5 shows a quality evaluation process in which the propagation speed of surface waves is used for quality evaluation. In this case, the quality evaluation unit 14 starts the quality evaluation process of FIG. 5 when a start condition is satisfied, which is satisfied when a predetermined time arrives or a predetermined start operation is performed, and first obtains the detection result (after amplification) of the sensor 2 recorded in the data recording device 4 (step S101).

Next, the quality evaluation unit 14 calculates the propagation velocity Vr of the surface wave actually generated in the test object based on the detection result acquired in step S101 (step S102). Specifically, the quality evaluation unit 14 calculates the propagation velocity Vr of the surface wave actually generated in the test object based on the difference in detection time between the surface waves generated at two locations detected by the first sensor 2A and the second sensor 2B, respectively.

Next, the quality evaluation unit 14 performs an evaluation of the quality of the object to be inspected based on the propagation speed Vr of the surface wave (actual surface wave) calculated in step S102 and the reference data RD (step S103). For example, when the quality of the object to be inspected is evaluated based on the degree of delay of the actual propagation speed (propagation speed of the actual surface wave) Vr, the quality evaluation unit 14 realizes the evaluation of the object to be inspected by comparing the actual propagation speed Vr calculated in step S102 with a predetermined reference value included in the "reference" of the reference data RD. This evaluation may be realized, for example, by presenting to the inspector through the monitor MO that the actual propagation speed Vr generated in the superabrasive layer 6a of the grinding wheel 6 is "good" if it is equal to or faster than the predetermined reference value, and "bad" if it is slower than the predetermined reference value (if it is less than the predetermined reference value). As an example, it is realized by presenting whether it is faster (equal to or faster) or slower (less than the predetermined reference value).

On the other hand, for example, when the longitudinal elastic modulus E of the object to be inspected is calculated as the quality of the object to be inspected, the quality evaluation unit 14 first calculates the propagation velocity Vs of the transverse wave of the object to be inspected by substituting the actual propagation velocity Vr calculated in step S102 and the information of the Poisson's ratio v included in the "standard" of the reference data RD into the formula (E). Next, the quality evaluation unit 14 calculates the longitudinal elastic modulus E of the object to be inspected by substituting the calculated propagation velocity Vs of the transverse wave and the information of the density ρ (corresponding to the object to be inspected this time) included in the "standard" of the reference data RD into the formula (B). In these calculations, for example, if the object to be inspected is a grinding wheel 6, the quality evaluation unit 14 identifies the Poisson's ratio v and density ρ corresponding to the grinding wheel 6 from the reference data RD, and uses the identified Poisson's ratio v, etc., for substitution into the formula (E). The quality evaluation unit 14 then presents the calculated longitudinal elastic modulus E (which may be an evaluation factor such as "good" as in the case of the degree of delay) to the inspector via the monitor MO as the quality of the object being inspected.

When the Young's modulus E of the object to be inspected is calculated as the quality of the object to be inspected, or when the quality is evaluated based on the degree of delay of the actual propagation speed Vr, the evaluation is performed as described above as an example. After such evaluation, the quality evaluation unit 14 ends the current quality evaluation process. As a result, the quality of the object to be inspected is evaluated through the quality inspection device 1. More specifically, the wave detection procedure and the quality evaluation procedure are realized through the quality inspection device 1. In other words, the quality inspection method of the present invention is realized through the quality inspection device 1.

As described above, according to this embodiment, the quality of the grinding wheel 6 (super abrasive wheel) is evaluated based on the surface waves generated on the grinding wheel 6 to be inspected. In other words, surface waves are used to evaluate the quality of the grinding wheel 6. Surface waves can occur not only on ordinary grinding wheels, but also on the abrasive layer of a super abrasive wheel. Therefore, the quality of not only ordinary grinding wheels, but also the super abrasive layer 6a of a super abrasive wheel can be evaluated using surface waves. In other words, the quality of not only ordinary grinding wheels but also super abrasive wheels can be evaluated. As a result, compared to sonic methods, etc., this method can be applied to quality inspection of a variety of grinding wheels. In addition, since the grinding wheel 6 can be directly evaluated using surface waves, the time and effort required to prepare such substitutes can be reduced compared to when the quality is evaluated through substitutes dedicated to inspection, for example.

In the above embodiment, the quality evaluation unit 14 of the computer device 5 functions as the speed calculation means and quality evaluation means of the present invention by executing the quality evaluation process of Fig. 5. Specifically, the quality evaluation unit 14 functions as the speed calculation means by executing step S102 of Fig. 5, and as the quality evaluation means by executing step S103 of Fig. 5.

The present invention is not limited to the above-mentioned embodiments, and may be implemented in various modified or altered forms. For example, in the above-mentioned embodiments, a superabrasive wheel is used as the grinding wheel 6. However, the quality inspection method and quality inspection device 1 of the present invention can also be applied to ordinary grinding wheels.

In the above embodiment, the longitudinal elastic modulus E is calculated based on the propagation velocity Vr of the surface wave. However, the present invention is not limited to this embodiment. For example, any suitable variable included in the above equations (A) to (C) may be used to calculate the longitudinal elastic modulus. Therefore, the quality inspection method of the present invention may be configured as a method for evaluating the quality of an object to be inspected based on various elastic waves, such as the propagation velocity Vp of a longitudinal wave or the propagation velocity Vs of a transverse wave.

In the above embodiment, a grinding wheel 6 is used as the object to be inspected. However, the present invention is not limited to this embodiment. Various objects in which elastic waves can be generated may be appropriately used as the object to be inspected. Therefore, the quality inspection method of the present invention is not limited to a grinding wheel 6, and may be configured as a method for inspecting the quality of such various objects to be inspected.

The quality inspection method of the present invention was carried out based on the quality inspection device 1 and procedure according to the above-mentioned embodiment. The conditions common to the examples are as follows.

The fixed distance WD1 of the quality inspection device 1 was set to 10 mm, and the specified interval WD2 was set to 40 mm (a length corresponding to an angle r of about 45 degrees). A mechanical pencil lead folding method was applied by folding the lead of the generator 7 (mechanical pencil) at a protruding length of 3 mm and an inclination angle of 30 degrees (the inclination angle with respect to the normal line at the contact point of the lead). Furthermore, an application (program) called "MEGA VIEW" (registered trademark) manufactured by Keyence Corporation was installed in the computer device 5, and was used to measure the waveform data of the surface waves. Similarly, an AE-901S (manufactured by NF Corporation) was used as the sensor 2 (AE sensor), an AE9501A (manufactured by NF Corporation) was used as the amplifier 3, and an NR-500 (manufactured by Keyence Corporation) was used as the data recording device 4.

Figure 6 shows the measurement results of the delay time of the surface wave at two locations measured under the above-mentioned conditions. In Figure 6, CH1 on the vertical axis indicates the detection result of the first sensor 2A, and CH2 indicates the detection result of the second sensor 2B. Meanwhile, the horizontal axis indicates the passage of time. As shown in Figure 6, there is a time lag (lag time) between the first waveform peak detected by the first sensor 2A and the first waveform peak detected by the second sensor 2B. In the following example, the propagation speed Vr of the surface wave is calculated (detected) based on the lag time starting from the first waveform peak at these two locations.

The generator 7 (mechanical pencil), the first sensor 2A, and the second sensor 2B were all installed at the center in the width direction of the superabrasive layer 6a. Furthermore, clay was attached to the wheel base metal at two locations where the first sensor 2A and the second sensor 2B were installed, blocking the surface waves propagating along the surface of the wheel base metal. However, it was confirmed in another preliminary experiment that the presence or absence of clay did not cause any disturbance in the waveform of the surface waves or any difference in the propagation time.

The first sensor 2A and the second sensor 2B are both configured as narrow-band AE sensors and are filtered so as not to measure waves other than those with frequencies close to the surface waves. The superabrasive wheels used in the examples are brand new and unused, unless otherwise specified (for example, defective wheels as described below). Among these superabrasive wheels, the resinoid bond wheels and metal bond wheels are configured as non-porous, while the vitrified bond wheels are configured as porous. The thickness (radial height) of the superabrasive layer 6a is all 3 mm.

In addition, in a preliminary investigation of the implementation of this embodiment, surface waves were measured using the quality inspection method of the present invention on the wheel working surface in a dulled state (super abrasive layer 6a) and on the wheel working surface after dressing and sharpening through several types of super abrasive wheels. The surface waves of both had the same waveform, and no difference in the propagation speed Vr was observed. For this reason, it is believed that the quality inspection method of the present invention is capable of measuring surface waves without affecting the protruding height of the abrasive grains or the state of wear. On the other hand, it is assumed that the base metal affects the propagation speed Vr of the surface waves when the abrasive layer becomes thin, but this was not verified in this embodiment.

Example 1
Before applying the quality inspection method of the present invention to the superabrasive wheel, in order to verify whether it is possible to measure surface waves using the quality inspection method of the present invention, a disk (outer diameter 200 mm x inner diameter 70 mm x width 5 mm) simulating a superabrasive wheel was made from the following four types of metal materials, quality inspection device 1 was attached to the circumferential surface of this disk, and the surface waves propagating along the circumferential surface were measured. The measurement was performed three times at different measurement points, and the average value of the three measurements was detected as the experimental value (implemented value).

Figure 7 shows the results of comparing the theoretical and experimental values of the propagation velocity Vr of the surface wave in the various materials mentioned above. In the example of Figure 7, the theoretical and experimental values are shown in a bar graph. The vertical axis of the bar graph indicates the propagation velocity Vr (propagation velocity of surface wave), and the horizontal axis indicates each disc material. In addition, the shades of the colors for each material in the bar graph indicate the theoretical value and the experimental value, respectively. More specifically, the darker the color, the more the theoretical value, and the lighter the experimental value.

As shown in Figure 7, the measurement results show that the relative error between the theoretical values and the experimental values is 0.4% to 7.8% for all materials. This allows the experimental values to be understood as equivalent to the theoretical values. As a result, it was confirmed that surface waves can be measured using the quality inspection method of the present invention.

In the example of FIG. 7, the theoretical values are quoted from the following two documents.
Reference 1: Teruo Kishi, Kazuhiko Kuribayashi, Metallurgy of Acoustic Emission (1), Metals, 47, 4 (1977) 16
Reference 2: Teruo Kishi, Material Evaluation by AE (1), Materials, 29, (1980) 323

Example 2
The quality inspection method and the quality inspection device 1 of the present invention were applied to a resinoid bond wheel and a metal bond wheel. The specifications of the resinoid bond wheel and the metal bond wheel used in the implementation of the quality inspection method of the present invention are SDC-N100B and MD-N100M, respectively. In addition, three types of grain sizes, 140, 270, and 400, were prepared as the resinoid bond wheel. Similarly, three types of grain sizes, 140, 270, and 600, were prepared as the metal bond wheel. SDC is a low-impact diamond abrasive grain with metal coating. MD is a high-impact diamond abrasive grain with no metal coating. In this embodiment, marks were made on the side of the wheel at 30 degree intervals, and the measurement points were changed based on these marks, and the surface waves were measured at 12 points on the abrasive layer. Each measurement point was measured five times, and the three values excluding the maximum and minimum of the measured values were averaged, and the value was taken as the value of each measurement point. Then, the values of the 12 measurement points were averaged, and the value was taken as the experimental value. In addition, since superabrasive wheels are expensive and difficult to purchase, the specifications other than those of the comparison target may not be the same. However, since the main purpose of this embodiment is to understand the characteristics of the surface wave, this point is ignored. In this embodiment, the difference in the propagation velocity Vr at each measurement point was a maximum of 7%.

Figure 8 shows the results of measuring the surface waves of the above-mentioned abrasive grain layers with different grain sizes. In the example of Figure 8, the measurement results (experimental values) are shown in a bar graph, similar to the example of Figure 7. The vertical axis of the bar graph shows the propagation speed Vr of the surface waves, and the horizontal axis shows the specifications (wheel specs) of each grain size by material. In addition, on the left side of the horizontal axis, three types of grain sizes of resinoid bond wheels (Resinoid Bond) are positioned in the order of 140, 270, and 400 from the left. On the other hand, on the right side of the horizontal axis, three types of grain sizes of metal bond wheels (Metal Bond) are positioned in the order of 140, 270, and 600 from the left.

As shown in Figure 8, it can be seen that the propagation speed Vr of the surface wave becomes slightly faster when the grain size is increased in both the resinoid bond wheel and the metal bond wheel. This is thought to be due to the fact that the number of abrasive grains increases as the grain size increases, since the concentration is the same. As shown by the above formulas (A) and (B), the speed of the elastic wave increases as the longitudinal elastic modulus increases. Although the adhesion between the diamond and the binder should be considered for both the resinoid bond wheel and the metal bond wheel, it is thought that the greater the number of abrasive grains, the higher the longitudinal elastic modulus of the abrasive grain layer becomes. In the mechanical pencil core compression method performed in this example, the frequency of the surface wave is at most about 400 kHz, and the wavelength is at least about 6.0 mm. In other words, the wavelength is much larger than the grain size. For this reason, it is thought that it is difficult to detect the difference in grain size using this method, but it is clear from the results of this example that there is a difference in the propagation speed Vr of the surface wave due to the difference in grain size. However, the relationship between grain size and surface wave may require additional experiments in the future, including the use of a method that can transmit high frequencies.

Example 3
The quality inspection method and the quality inspection device 1 of the present invention were applied to abrasive grain layers with different concentrations. The specifications of the wheels used in this example were SDC400N-B with concentrations of 75 and 100. The method of deriving the experimental values (implemented values) in the following examples, including this example, is the same as in Example 2.

Figure 9 shows the results of measuring the surface waves of abrasive layers with different concentrations as described above. The example in Figure 9 shows the results of measuring the surface waves in a bar graph, similar to the examples in Figure 8 and others. The vertical and horizontal axes of the bar graph are the same as the example in Figure 8, but in the example in Figure 9, the concentrations 75 and 100 of SDC400N-B are positioned on the horizontal axis, in that order, from the left.

As shown in Figure 9, it can be seen that the higher the concentration, the faster the propagation velocity Vr of the surface waves. This is thought to be due to the fact that the number of abrasive grains increases, as in the example of Figure 8. As a result, by interpreting this result in the opposite way, it can be seen that the faster the propagation velocity Vr of the surface waves, the higher the concentration. For this reason, it is thought that the degree of concentration of the abrasive grain layer can be inspected (evaluated) by comparing the propagation velocity Vr of the surface waves with a predetermined reference value (e.g., a theoretical value, etc.).

Example 4
The quality inspection method and quality inspection device 1 of the present invention were applied to diamond wheels with different bonding agents. The types of bonding agents were resinoid bond, vitrified bond, and metal bond. The wheels used in this embodiment were three types of resinoid bond with grain sizes of 140, 230, and 400, two types of vitrified bond with grain sizes of 140 and 200, and three types of metal bond with grain sizes of 140, 270, and 600. Furthermore, for the resinoid bond, two types with different concentrations of 75 and 100 were used for the grain size of 400. The resinoid bond wheel and the metal bond wheel were non-porous. The vitrified bond wheel had holes.

Figure 10 is a diagram showing the results of measuring the surface waves of diamond wheels with different bonding agents. The example of Figure 10 shows the measurement results in a bar graph, similar to the examples of Figure 8 and others. The vertical and horizontal axes of the bar graph are the same as the examples of Figure 8 and others, but in the example of Figure 10, the horizontal axis is distinguished from the left in the order of resinoid bond, vitrified bond, and metal bond. In addition, for resinoid bonds, SDC140N100B (grain size 140, concentration 100), SDC230N100B (grain size 230, concentration 100), SDC400N100B (grain size 400, concentration 100), SDC400N75B (grain size 400, concentration 75), and SDC400N100B (grain size 400, concentration 100) are located on the horizontal axis in that order from the left. For vitrified bonds, SD140N100V (grain size 140, concentration 100) and SD200N100V (grain size 200, concentration 100) are positioned on the horizontal axis from the left. For metal bonds, MD140N50V (grain size 140, concentration 50), MD270N50V (grain size 270, concentration 50), and MD600N50V (grain size 600, concentration 50) are positioned on the horizontal axis from the left.

As shown in Figure 10, although the surface wave propagation speed Vr differs depending on the detailed specifications, the resinoid bond has the slowest surface wave propagation speed Vr, followed by the vitrified bond and the metal bond, which are gradually faster in that order. This order is correlated with the modulus of elasticity E, so it is thought that the macroscopic modulus of elasticity E as the structure of the abrasive layer affects the speed of the surface wave, as in the example of Figure 8 (results of Example 2). In addition, the fast propagation speed Vr of the metal bond wheel is also thought to be due to the adhesion between the diamond and the binder, but this point may require separate detailed consideration. On the other hand, since the vitrified bond wheel has air holes, it was predicted that the surface wave propagation speed Vr would be slow, but it is slower than the resinoid bond wheel. This is thought to be due to the fact that the modulus of elasticity has a greater effect on the propagation speed Vr than the air holes.

Example 5
The quality inspection method and the quality inspection device 1 of the present invention were applied to different types of superabrasive grains using the same binder. In this embodiment, a resinoid bond was used as the same binder. Diamond and CBN were used as different types of superabrasive grains. Specifically, the wheels used in this embodiment were three types of diamond wheels with grain sizes of 140, 230, and 400, and two types of CBN wheels with grain sizes of 140 and 400. Furthermore, two types of diamond wheels with different concentrations of 100 and 75 were used. In this embodiment, the experimental values of the diamond wheels are the same as those in the example of FIG. 10 (results of embodiment 4).

Figure 11 is a diagram showing the relationship between the types of superabrasive grains and surface waves. The example of Figure 11 shows the measurement results of surface waves in a bar graph, similar to the examples of Figure 8 and others. The vertical and horizontal axes of the bar graph are the same as the examples of Figure 8 and others, but in the example of Figure 11, the horizontal axis distinguishes diamond wheels and CBN wheels, in that order, from the left. In addition, for diamond wheels, SDC140N100B (grain size 140, concentration 100), SDC230N100B (grain size 230, concentration 100), SDC400N100B (grain size 400, concentration 100), SDC400N75B (grain size 400, concentration 75), and SDC400N100B (grain size 400, concentration 100) are located on the horizontal axis, in that order, from the left. Similarly, for CBN wheels, CBN140N125B (grain size 140, concentration 125) and CBN400N125B (grain size 400, concentration 125) are located on the horizontal axis from the left.

As shown in Figure 11, for both abrasive layer specifications, diamond has a higher surface wave propagation velocity Vr than CBN. This result is also presumably influenced by the difference in the Young's modulus E between diamond and CBN.

Example 6
The quality inspection method and the quality inspection device 1 of the present invention were applied to a defective abrasive layer and a defect-free abrasive layer. The wheel used in this example was a diamond wheel. The specifications of the diamond were a grit size of 230 and a concentration of 75. Of these wheels with the same specifications, only one had a defect.

Figure 12 is a diagram showing a comparison of the propagation speed Vr of the surface wave when the abrasive layer of the above-mentioned wheel has a defect and when it does not have a defect. The example of Figure 12 shows the measurement results of the surface wave in a bar graph, similar to the example of Figure 8, etc. The vertical and horizontal axes of the bar graph are the same as the example of Figure 8, etc., but in the example of Figure 12, the horizontal axis shows the experimental results of a wheel SDC230N75B (grain size 230, concentration 75) with a defect and the same wheel without a defect, in that order, from the left. Also, in the example of Figure 12, the defective abrasive layer is a wheel in which part of the abrasive layer was destroyed due to an incorrect operation during the grinding operation (see also the photograph portion shown in Figure 12). The first sensor 2A and the second sensor 2B are arranged to straddle this defective part and detect the surface wave.

As shown in Figure 12, when the abrasive layer has the same specifications, the propagation velocity Vr is slower when there is a defect than when there is no defect. This is thought to be mainly due to the scattering of surface waves by the defect.

Figure 13 is a diagram showing a comparison of the propagation speed Vr of the surface wave when there is a defect in the abrasive layer of the wheel as in the example of Figure 12 and when there is no defect. The difference from the example of Figure 12 is the defective portion formed in the wheel. Specifically, in the example of Figure 13, part of the abrasive layer of the wheel is cut by wire cutting, forming a defective portion (see also the photographic portion shown in Figure 13). The first sensor 2A and the second sensor 2B are positioned to straddle this defective portion as in the example of Figure 12, and detect the surface wave.

As shown in Figure 13, similar to the example in Figure 12, the propagation speed Vr is slower in the part cut by wire cutting (defective part) than in the normal part. The examples in Figures 12 and 13 suggest that the presence or absence of defects in the abrasive layer can be determined by the propagation speed Vr of the surface wave. For this reason, it is believed that the presence or absence of defects can be inspected (evaluated) by comparing the propagation speed Vr of the surface wave with a predetermined reference value (e.g., a theoretical value, etc.). In other words, it is believed that the quality of the abrasive layer (presence or absence of defects) can be evaluated based on the degree of delay in the propagation speed Vr relative to the predetermined reference value.

In this experiment, because the superabrasive wheels are expensive, it was not possible to make the specifications of the wheels other than those being compared identical, and it was not possible to detect the relationship between the detailed specifications of the abrasive layer (including the thickness of the abrasive layer) and the propagation speed Vr. For this reason, it would be preferable to increase future experimental (experimental) data, including the detection of such relationships. However, it is clear from the results of this experiment that differences can be seen in the propagation speed Vr of the surface waves depending on the specifications of the abrasive layer, and a certain tendency has been identified. For this reason, it is thought that there is a high possibility that the quality of the abrasive layer, such as the abrasive distribution (uniformity) and unevenness in the degree of bonding, can be broadly evaluated not only based on the presence or absence of defects, but also based on the propagation speed Vr of the surface waves.

(Example 7)
The quality inspection method and the quality inspection device 1 of the present invention were applied to the calculation of the Young's modulus E of various materials. The materials used in the calculation of the Young's modulus E in this embodiment are aluminum alloy, copper, brass, and stainless steel. The experimental value of the Young's modulus E is calculated based on the above-mentioned formula (E) and formula (B), and the mathematical processing system Mathematica (registered trademark) is used for the calculation.

Figure 14 is a table showing the values of Poisson's ratio v and density ρ for the various materials mentioned above. As shown in the table in Figure 14, the Poisson's ratio v and density ρ of aluminum alloy are 0.34 and 2.69, respectively. Similarly, the Poisson's ratio v and density ρ of copper are 0.34 and 8.96, respectively, and the Poisson's ratio v and density ρ of copper are 0.35 and 8.71, respectively. The Poisson's ratio v and density ρ of stainless steel are 0.3 and 7.93, respectively. In this example, these Poisson's ratios v and densities ρ are used as reference information for calculating experimental values.

Figure 15 is a diagram showing theoretical and experimental values of the modulus of elasticity E for the various materials mentioned above. In the example of Figure 15, these values are shown as a bar graph. The vertical axis of the bar graph shows the modulus of elasticity E, and the horizontal axis shows the disc material. In addition, in the bar graph of Figure 15, theoretical values and experimental values are distinguished by the shade of the color scheme. Specifically, in the example of Figure 15, the darker colors show the theoretical values, and the lighter colors show the experimental values. Note that in the example of Figure 15, the value of the modulus of elasticity E, which is generally shown as the theoretical value, is used.

As shown in Figure 15, there is a high degree of correspondence between the theoretical values and the experimental values for the various materials mentioned above, to the extent that they can be considered equivalent. For this reason, the method for calculating the Young's modulus E based on the quality inspection method of the present invention is considered to be valid.

(Example 8)
Based on the results of Example 7, the quality inspection method and quality inspection device 1 of the present invention were applied to the calculation of the Young's modulus E in the abrasive layer of a superabrasive wheel. Three types of wheels, SDC140N100B, CB140N125B, and MD140N50M, were used in this example. Since vitrified bonds have pores, it is often difficult to calculate the Poisson's ratio v and density ρ. For this reason, a non-porous abrasive layer is considered in this example.

Figure 16 is a table showing the values of Poisson's ratio v and density ρ used in this embodiment. As shown in Figure 16, for convenience, the Poisson's ratio v is set to 0.2 for the resinoid abrasive layer (SDC140N100B and CB140N125B) and 0.3 for the metal bond abrasive layer (MD140N50M) in this embodiment. On the other hand, since both abrasive layers are non-porous, the density ρ is calculated by proportional calculation from the concentration (prevalence ratio) of the superabrasive and the binder. In the calculation based on this proportional calculation, the values of diamond and CBN are used for the superabrasive. Similarly, the value of Bakelite is used for the binder in the resinoid bond, and the value of bronze is used for the binder in the metal bond. As a result, in this example, density ρ values of 1.85, 1.98, and 8.28 are used for SDC140N100B, CB140N125B, and MD140N50M, respectively.

Figure 17 is a diagram showing the calculated values of the Young's modulus E in the abrasive layer of the above-mentioned superabrasive wheel. In the example of Figure 17, the calculation results are shown as a bar graph. The vertical axis of the bar graph shows the Young's modulus E (calculated value), and the horizontal axis shows the wheel specifications. In the example of Figure 17, SDC140N100B, CB140N125B, and MD140N50M are positioned on the horizontal axis in this order from the left.

As shown in Figure 17, the modulus of elasticity E calculated from the surface waves is 43 Gpa (gigapascals) for SDC140N100B, 55 Gpa, and 631 Gpa for CB140N125B, and MD140N50M, respectively. The general modulus of elasticity E of the abrasive layer of a resinoid bond wheel is considered to be approximately 20 to 50 Gpa. For this reason, the modulus of elasticity E calculated in this example is considered to be a reasonable value for a resinoid bond wheel, whether it is made of diamond or CBN.

On the other hand, the general elastic modulus E of the abrasive grain layer of a metal bond wheel is considered to be approximately 100 to 150 GPa. For this reason, the general elastic modulus E calculated in this embodiment differs from this general value, but this is thought to be mainly due to the density ρ of the abrasive grain layer of the metal bond wheel being an inappropriate value. As a result, although appropriate values for the Poisson's ratio v and density ρ are required, it can be seen that the quality inspection method of the present invention makes it possible to calculate a reasonably reasonable value for the general elastic modulus E of the abrasive grain layer of a superabrasive wheel.

1 Quality inspection device 2 Sensor (detection means, elastic wave detection device)
5 Computer device 6 Grindstone 7 Generator (wave generating means)
14 Quality evaluation unit (speed calculation means, quality evaluation means)
2A First sensor (first detection means, elastic wave detection device)
2B Second sensor (second detection means, elastic wave detection device)
WD2 Predetermined interval

Claims (6)

A quality inspection method for inspecting the quality of a grinding wheel for grinding an object, comprising the steps of:
a wave generating step of actually generating a surface wave on the grindstone through a wave generating means for generating a surface wave on the grindstone;
a wave detection step of detecting an actual surface wave as a surface wave actually generated on the grindstone through a detection means for detecting the surface wave of the grindstone;
a quality evaluation step of evaluating quality of the grinding wheel based on the actual surface wave and discrimination information for discriminating quality of the grinding wheel using the actual surface wave;
A quality inspection method comprising: the wave detection step is adapted to detect a propagation velocity of the surface wave as the actual surface wave;
The quality inspection method according to claim 1 , wherein the quality evaluation procedure is configured to utilize a propagation velocity of the surface wave as the actual surface wave, and to evaluate the quality of the grinding wheel based on the propagation velocity and the discrimination information. the detection means includes a first detection means and a second detection means for detecting the actual surface wave at two locations of the grindstone spaced a predetermined distance apart,
3. The quality inspection method according to claim 2, wherein the wave detection step includes: a first detection step of detecting the actual surface waves at the two locations through the first detection means and the second detection means, respectively; and a second detection step of detecting a propagation velocity of the actual surface wave by calculating the propagation velocity based on a delay time between a detection time of the actual surface wave by the first detection means and a detection time of the actual surface wave by the second detection means. The discrimination information includes information on a reference propagation speed as a propagation speed that should function as a standard for discriminating the quality of the grinding wheel,
The quality inspection method according to claim 2 or 3, wherein the quality evaluation procedure is configured to evaluate the quality of the grinding wheel by comparing the propagation velocity of the actual surface wave with the reference propagation velocity. The discrimination information includes information on a Poisson's ratio and information on density of the grindstone,
The quality assessment procedure includes:
a first evaluation step of calculating the propagation velocity of the transverse wave based on the formula (1) when the propagation velocity of the actual surface wave is Vr , the Poisson's ratio is v, and the propagation velocity of the transverse wave related to the actual surface wave is Vs;
a second evaluation step of calculating the longitudinal elastic modulus of the grinding wheel based on the formula (2) as an evaluation of the quality of the grinding wheel, where the density is ρ and the longitudinal elastic modulus of the grinding wheel is E.

A quality inspection device for inspecting the quality of a grinding wheel for grinding an object, comprising:
two elastic wave detectors arranged at two locations on the grindstone at a predetermined distance from each other to detect elastic waves when elastic waves are generated in the grindstone through a wave generating means;
a velocity calculation means for calculating an actual propagation velocity as a propagation velocity of the actual surface wave based on a delay time between the two points generated in an actual surface wave as a surface wave detected by each elastic wave inspection device among the elastic waves;
a quality evaluation means for evaluating a quality of the grindstone based on the actual propagation speed and discrimination information for discriminating the quality of the grindstone by utilizing the actual propagation speed;
A quality inspection device comprising:

Images