JP6384263B2 - Echo characteristic correction method - Google Patents

Description

  In the present invention, when the thickness of a liquid filled in a part of a space formed around the contact surface between the first member and the second member formed of different materials is measured using ultrasonic waves. The present invention relates to an echo characteristic correction method for correcting an echo characteristic used in the above.

  For example, the first member of the substantially flat glass plate is brought into contact with the second member of the substantially spherical glass member, and at least part of the space formed around the contact surface including the contact points of the first member and the second member. When lubricating oil is filled, the film thickness of the oil film can be measured by an optical interference measurement method using optical interference fringes. However, in this optical interference measurement method, since at least one of the first member and the second member must be transparent, for example, a non-transparent metal race (corresponding to the first member) and a non-transparent steel ball ( It corresponds to the second member) and cannot be applied to a rolling bearing device or the like constituted by

  As a method of measuring the film thickness of the liquid filled in at least a part of the space formed around the contact surface by bringing the curved surface of the non-transparent second member into contact with the non-transparent first member, An ultrasonic measurement method using sound waves can be used. The ultrasonic measurement method can measure the film thickness according to the echo intensity by detecting the intensity (echo intensity) of the reflected wave of the transmitted ultrasonic wave.

  For example, Patent Document 1 discloses an ultrasonic probe for the film thickness of an oil film formed between a non-transparent cylinder (corresponding to a first member) and a non-transparent piston ring (corresponding to a second member). A method of obtaining a film thickness calibration curve for film thickness measurement, which can easily and accurately obtain calibration curve data used when measuring using a child, is disclosed. In Patent Document 1, an echo height signal that is a reflected wave from a film forming unit is received by an ultrasonic probe for each of different film thicknesses, an echo height ratio obtained by standardizing the echo height signal is calculated, A change ratio of the echo height ratio between the set first film thickness value and the second film thickness value is calculated, and the relationship between the change ratio and the film thickness value is acquired as a calibration curve.

JP 2007-212410 A

  In invention of patent document 1, since the cylinder (1st member) and the piston ring (2nd member) are assumed, the case where the cylinder and the piston ring are contacting is not assumed. In other words, Patent Document 1 shows a relationship between a cylinder and a piston ring that are not in contact with each other, and a film thickness between the cylinder and the piston ring and a standardized echo height (echo height ratio). . For this reason, as the film thickness increases from zero, the standardized echo height gradually increases. Therefore, if the standardized echo height (echo height ratio) is measured, the film thickness can be specified as one.

  However, when the first member and the second member made of different materials are in contact with each other, as described in Patent Document 1, the film thickness is such that the echo height ratio increases as the film thickness increases. In some cases, the relationship with the echo height ratio cannot be obtained. When the first member and the second member made of different materials are in contact with each other, as shown in the example of FIG. 5, the distance from the contact center S that is the center of the contact surface between the first member 21 and the second member 22 The distance / echo ratio characteristic (“distance / echo ratio characteristic” in FIG. 5 (when the first member and the second member are made of different materials) indicating the relationship with the echo ratio gradually increases the distance from the contact center S from zero. The echo ratio has a characteristic that the echo ratio gradually decreases to near the boundary of the contact surface, and gradually increases when the contact surface boundary is exceeded. Is the distance from the contact center S theoretically determined from this “distance / echo ratio characteristic” (when the first member and the second member are made of different materials) and the shapes of the first member 21 and the second member 22. Shows the relationship between distance and distance (gap between the first member and the second member) Characteristics ”(see FIG. 5) are prepared in advance, and the echo ratio (H) is the echo intensity based on the echo intensity measured in advance only with the second member and the first member from which the liquid is removed. Is the value obtained by dividing the echo intensity (h) measured by the measurement object by the reference echo intensity (ho) (H = h / ho). The echo ratio is obtained from the echo intensity measured at the measurement object, and the distance corresponding to the measured echo ratio is calculated from the obtained echo ratio and the “distance / echo ratio characteristics” (when the first member and the second member are made of different materials). The distance (that is, the film thickness) is obtained from the obtained distance and the “distance / spacing characteristics.” However, the “distance / echo ratio characteristics” shown in the example of FIG. In the case of), for example, from the measured echo intensity When the calculated echo ratio is H1AB, the distance obtained from the echo ratio H1AB and “distance / echo ratio characteristics” (when the first member and the second member are made of different materials) is not specified as one. The distance D1A and the distance D1B are specified, and the distance D1A, the distance D1B, and the “distance / interval characteristics” specify the distance (film thickness) L1A and the distance (film thickness) L1B. The film thickness cannot be specified as one, and this problem cannot be solved even by calibrating using the invention described in Patent Document 1.

  The present invention was devised in view of such points, and at least a part of a space formed around the contact surface where the first member and the second member formed of different materials are brought into contact with each other. The distance / echo ratio characteristic indicating the relationship between the distance from the contact center, which is the center of the contact surface of the first member and the second member, and the echo ratio is used when measuring the film thickness of the liquid filled in It is an object of the present invention to provide an echo characteristic correction method in which the echo ratio is gradually increased as the distance from the contact center increases from zero.

  In order to solve the above problems, the echo characteristic correction method according to the present invention takes the following means. A first aspect of the present invention is a liquid film filled in at least a part of a space formed around a contact surface where a first member and a second member made of different materials are brought into contact with each other. This is an echo characteristic correction method for correcting an echo characteristic when measuring thickness using ultrasonic waves. The first member has a front surface and a back surface, and the shape of the second member is such that the surface facing the back surface of the first member has at least one curvature toward the first member. The first member and the second member are arranged up and down so that the surface of the second member contacts the back surface of the first member with the first member as the upper side, At least a part of the space formed around the contact surface between the first member and the second member is filled with liquid, and is disposed on the surface side of the first member via an ultrasonic conduction medium. And an ultrasonic probe for transmitting an ultrasonic wave from the front surface to the back surface of the first member and detecting a reflected wave of the transmitted ultrasonic wave, and a control means for controlling the ultrasonic probe. Then, an ultrasonic wave is transmitted from the ultrasonic probe, and the transmitted ultrasonic wave is reflected on the back surface of the first member, and the transmitted ultrasonic wave is reflected on the second member. A combined reflected wave detection step for detecting an echo intensity of a combined reflected wave obtained by combining the second member surface reflected wave reflected by the surface at least from a contact center that is the center of the contact surface to a predetermined distance. The first echo by transmitting ultrasonic waves from the front surface to the back surface of the first member in a state where the second member and the liquid are excluded and only the first member is present, with the reference echo intensity determined in advance. Echo ratio calculation for obtaining an echo ratio obtained by dividing the echo intensity detected in the combined reflected wave detection step with the reference echo intensity based on the echo intensity of the first member back surface reflected wave reflected on the back surface of the member Step and A distance / echo ratio characteristic indicating a relationship between a distance from the contact center and an echo ratio of each distance from the contact center obtained in the echo ratio calculating step, wherein the distance from the contact center is the contact ratio. The distance / echo has a tendency that the echo ratio gradually decreases until near the boundary of the surface, and the echo ratio tends to increase gradually when the distance from the contact center exceeds the vicinity of the boundary. The ratio characteristic is corrected based on the size of the contact surface and the sound pressure intensity distribution characteristic of the ultrasonic wave transmitted from the ultrasonic probe, the echo ratio from the contact center to the vicinity of the boundary, A distance / corrected echo ratio characteristic creating step for creating a distance / corrected echo ratio characteristic having a tendency that the echo ratio gradually increases as the distance from the contact center increases. .

  Next, a second invention of the present invention is the echo characteristic correcting method according to the first invention, wherein the ultrasonic wave transmitted from the ultrasonic probe is capable of adjusting a focal position, The focal point is adjusted to the back surface of one member, and the echo ratio from the contact center to the vicinity of the boundary is determined as the contact between the first member and the second member in the distance / corrected echo ratio characteristic creating step. Based on a virtual contact cylinder that is a virtual substantially circular cylinder located up to the lower surface of the second member with a substantially circular surface as the upper surface, and a sound pressure intensity distribution that is obtained in advance downward from the focal point of the ultrasonic wave. An echo that is corrected with a correction amount based on a virtual sound pressure intensity distribution solid that is a virtual solid that has a cross-sectional contour shape cut along the transmission direction of the ultrasonic waves and has a normal distribution curve shape. This is a characteristic correction method.

  Next, a third invention of the present invention is the echo characteristic correction method according to the second invention, wherein, in the distance / corrected echo ratio characteristic creation step, the contact center from the contact center to the vicinity of the boundary. The echo ratio at each distance is expressed as “echo ratio at each distance” − “reflectance of the ultrasonic wave at the contact surface” * “the virtual contact cylinder and the virtual sound pressure intensity distribution solid at each distance”. This is an echo characteristic correction method obtained by “volume of overlapping portion / volume of virtual sound pressure intensity distribution solid”.

  According to the first invention, as the distance from the contact center increases from zero, the echo ratio gradually decreases to the vicinity of the boundary of the contact surface, and gradually increases when the vicinity of the boundary of the contact surface is exceeded. In order to correct the echo ratio characteristic to a distance / corrected echo ratio characteristic in which the echo ratio tends to gradually increase as the distance from the contact center increases from zero, the first member and the second member contact each other. It is possible to appropriately correct based on the size of the contact surface and the sound pressure intensity distribution characteristic of the ultrasonic wave transmitted from the ultrasonic probe.

  According to the second invention, by correcting based on the virtual contact cylinder based on the size of the contact surface and the virtual sound pressure intensity distribution solid based on the ultrasonic sound pressure intensity distribution, As the distance increases from zero, the echo ratio gradually decreases to the vicinity of the boundary of the contact surface, and gradually increases when it exceeds the boundary of the contact surface. Thus, it is possible to appropriately correct the distance / corrected echo ratio characteristic in which the echo ratio tends to gradually increase as the value increases from zero.

  According to the third aspect of the invention, the distance / echo ratio characteristic can be more specifically and appropriately corrected to the distance / correction echo ratio characteristic.

It is a figure explaining the example of the external appearance of the rolling bearing apparatus which has an outer ring | wheel, an inner ring | wheel, and a some rolling element. It is II-II sectional drawing in FIG. It is a figure explaining the example which modeled the outer ring | wheel and rolling element in FIG. It is a figure explaining the example of the whole structure of an ultrasonic measuring device. Example of distance / echo ratio characteristics (in the case where the first member and the second member are made of different materials) indicating the relationship between the distance from the contact center and the echo ratio, the distance from the contact center, the first member and the second member Examples of distance / echo characteristics indicating the relationship between the distance to the center and distance / echo ratio characteristics indicating the relationship between the distance from the contact center and the echo ratio (when the first member and the second member are made of the same material) It is a figure explaining an example. It is a figure explaining the sound pressure intensity distribution which spreads below the focus of the transmitted ultrasonic wave, and the measuring method of the said sound pressure intensity distribution. It is a figure explaining the schematic shape of the measured sound pressure intensity distribution. It is the top view and side view explaining the superposition state of a virtual contact cylinder and a virtual sound pressure intensity distribution solid. Examples of distance / echo ratio characteristics (in the case where the first member and the second member are made of different materials) showing the relationship between the distance from the contact center and the echo ratio, the distance from the contact center, and the virtual sound pressure intensity distribution solid Based on distance / superimposed volume ratio characteristics example showing the relationship between the volume ratio of superimposed volume of virtual contact cylinder and virtual sound pressure intensity distribution solid to volume, distance / echo ratio characteristics and distance / superimposed volume ratio characteristics It is a figure explaining the example of the correct | amended distance and correction | amendment echo ratio characteristic.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing. In the drawings in which the X axis, the Y axis, and the Z axis are described, the X axis, the Y axis, and the Z axis are orthogonal to each other, and the Z axis indicates a direction that extends vertically upward.

● [Example of measurement target of liquid film thickness (Fig. 1, Fig. 2) and model of measurement target (Fig. 3)]
FIG. 1 shows an appearance of a rolling bearing device 100 as an example of a liquid film thickness measurement object, and FIG. 2 shows a II-II cross-sectional view of the rolling bearing device 100 of FIG. The rolling bearing device 100 includes an outer ring 121, an inner ring 123, a plurality of rolling elements 122, and the like. In addition, in the example of FIG.1 and FIG.2, description of the holder | retainer holding the space | interval of the adjacent rolling element 122 is abbreviate | omitted.

  As shown in FIGS. 1 and 2, the outer ring 121 has an annular shape having a concave outer ring side raceway surface 121K on the inner peripheral surface. The inner ring 123 has an annular shape having a concave inner ring side raceway surface 123K on the outer peripheral surface. As shown in FIG. 2, a liquid film M (oil film) filled with lubricating oil is formed in at least a part of the space formed around the contact surface between the outer ring raceway surface 121K and the rolling element 122. ing. A liquid film M (oil film) filled with lubricating oil is also formed in at least a part of the space formed around the contact surface between the inner ring raceway surface 123K and the rolling element 122. In the present embodiment, in FIG. 2, ultrasonic waves are transmitted from the surface 121A side of the outer ring 121 toward the back surface 121B side of the outer ring 121, and the back surface 121B of the outer ring 121 and the surface 122A ( A method of correcting the echo characteristics when measuring the film thickness of the liquid film M filled in at least a part of the space formed around the contact surface including the contact point with the surface facing the outer ring) will be described.

  FIG. 3 shows a model that is convenient for measurement with respect to the shape of the outer ring and the shape of the rolling element in the rolling bearing device 100, and the following description will be made using the model shape of FIG. In the model of FIG. 3, a substantially flat first member 21 having a constant thickness 21T in the Z-axis direction is used instead of the outer ring, and at least one curvature is provided toward the first member 21 instead of the rolling element. A second member 22 having a convex shape is used. The second member 22 shown in FIG. 3 has a curvature including the contact center S that is the center of the contact surface, the curvature between the outer peripheral portion SL and the outer peripheral portion SR, the left side of the outer peripheral portion SL, and the outer peripheral portion SR. Is a member having a curvature different from the curvature on the right side. The first member 21 and the second member 22 are in contact with each other at the contact surface including the contact center S, and the liquid film M is formed in at least a part of the space formed around the contact surface including the contact center S. Is formed. Reference numeral 21A indicates the upper surface (front surface) of the first member 21, reference numeral 21B indicates the lower surface (back surface) of the first member 21, and reference numeral 22A indicates the upper surface (front surface of the first member 21). 22B indicates the lower surface (back surface) of the second member 22. The contact center S indicates a point that is the center position of the contact surface where the first member 21 and the second member 22 are in contact with each other.

● [Overall configuration of ultrasonic measuring device 1 (FIG. 4)]
Next, an example of the overall configuration of the ultrasonic measurement apparatus 1 will be described with reference to FIG. The ultrasonic measurement apparatus 1 includes an ultrasonic probe 40, a control unit 60, a storage unit, a support member 83, bases 81 and 82, a probe holder 72, a probe arm 71, a medium holding member 51, a seal member 52, and the like. Have. In addition, about the state of the 1st member 21 and the 2nd member 22 which were piled up and down, since it is as showing in FIG. 3, description is abbreviate | omitted.

  The ultrasonic probe 40 is supported by a probe arm 71 via a probe holder 72. The ultrasonic probe 40 transmits ultrasonic waves from the upper surface (front surface) to the lower surface (back surface) of the first member 21 based on a control signal from the control means 60. And the ultrasonic probe 40 detects the reflected wave with respect to the transmitted ultrasonic wave, and outputs a detection signal to a control means. Note that the tip of the ultrasonic probe 40 that transmits ultrasonic waves and receives reflected waves is disposed so as to be immersed in the ultrasonic conductive medium B. Note that the ultrasonic probe 40 has a plurality of ultrasonic probes, and the ultrasonic waves transmitted by the plurality of ultrasonic probes at respective timings form a beam to form a focal point P. The control means 60 can adjust the position of the focal point P by appropriately adjusting the timing of the ultrasonic waves transmitted from each of the plurality of ultrasonic probes. The position of the focal point P is adjusted to be the lower surface of the first member 21.

  The control means 60 is, for example, a personal computer and contains a storage means. The control means 60 outputs a control signal to the ultrasonic probe 40 and takes in a detection signal from the ultrasonic probe 40. The control unit 60 can output a control signal to the probe arm 71 to move the position of the ultrasonic probe 40 in the X-axis direction and the Y-axis direction. As will be described later, the storage means stores reference echo intensity, distance / echo ratio characteristics, distance / interval characteristics, distance / superimposed volume ratio characteristics, distance / corrected echo ratio characteristics, and the like.

  The support member 83 holds the first member 21 and the second member 22 stacked one above the other and presses the first member 21 against the second member 22 with a predetermined load. The bases 81 and 82 are tables for fixing the support member 83.

  The probe holder 72 is attached to the probe arm 71 and holds the ultrasonic probe 40. The probe arm 71 moves the ultrasonic probe 40 held by the probe holder 72 within the XY plane based on a control signal from the control means 60.

  The medium holding member 51 is a medium capable of transmitting ultrasonic waves into a concave space formed by the inner surface of the medium holding member 51 and the upper surface of the first member 21 (and the upper surface of the support member 83). An ultrasonic conducting medium B (for example, water) is held. The seal member 52 seals between the medium holding member 51 and the support member 83.

● [Procedure for obtaining distance / echo ratio characteristics using the ultrasonic measurement apparatus 1 (FIG. 5)]
Next, using the ultrasonic measurement apparatus 1 described above, the ultrasonic probe 40 is moved in the X-axis direction (FIG. 5) from the position directly above the contact center S of the contact surface between the first member 21 and the second member 22. A method of acquiring distance / echo ratio characteristics based on the transmission of ultrasonic waves while scanning in the right direction), detecting the echo intensity of reflected waves with respect to the transmitted ultrasonic waves, and the echo intensity will be described. In FIG. 5, reference sign SS indicates a contact boundary indicating a position that is a boundary of the contact surface between the first member 21 and the second member 22.

  The control means 60 transmits an ultrasonic wave from the ultrasonic probe 40, and the transmitted ultrasonic wave is reflected on the back surface (lower surface) of the first member 21, and the transmitted ultrasonic wave is first. The echo intensity (maximum amplitude of the reflected wave) of the combined reflected wave obtained by combining the second member surface reflected wave reflected by the surface (upper surface) of the two members 22 is at least a predetermined distance from the contact center S in the X-axis direction. Detect until the position. This step corresponds to a composite reflected wave detection step.

Next, the control means 60 is the reference echo intensity obtained in advance (from the state having the first member 21, the second member 22, and the liquid film M shown in FIG. 5) and the second member 22 and the liquid (liquid film M). Based on the echo intensity of the first member back surface reflected wave transmitted from the upper surface of the first member 21 to the lower surface and reflected by the lower surface of the first member 21 with only the first member 21 removed Each echo intensity corresponding to each distance is obtained by dividing each echo intensity corresponding to each distance detected in the combined reflected wave detection step by the reference echo intensity. Note that the reference echo intensity is an average value of echo intensity from the contact center S to the position at the predetermined distance, for example, when only the first member 21 is used. Here, assuming that each echo ratio corresponding to each distance = H, each echo intensity measured at each distance = h, and reference echo intensity = ho, the echo ratio H at each distance is expressed by the following (Equation 1). Ask. This step corresponds to an echo ratio calculation step.
H = h / ho (Formula 1)

[When the first member 21 and the second member 22 are made of the same material]
When the first member 21 and the second member 22 are made of the same material, the distance / echo ratio characteristic indicating the relationship between the distance from the contact center S and the echo ratio H obtained by the above procedure is shown in FIG. 5, “Distance / Echo Ratio Characteristics” (when the first member and the second member are made of the same material). In this characteristic, since the echo ratio has a tendency to gradually increase as the distance from the contact center S increases from zero, when the echo ratio H is specified, the distance (distance from the contact center S) is determined. Can be specified as one. In addition, the storage means theoretically in advance from the reference echo intensity, the shape of the first member 21 and the second member 22 (particularly, the radius of curvature of each position of the second member 22), Hertz contact theory, contact load and the like. The obtained “distance / interval characteristics” indicating the relationship between the distance from the contact center S and the interval (gap between the first member and the second member) (shown in FIG. 5) is stored. When the first member 21 and the second member 22 are made of the same material, for example, when the obtained echo ratio is H1A, the control means 60 determines the echo ratio H1A and the “distance / echo ratio characteristics” in FIG. ] (When the first member and the second member are made of the same material), the distance D1A is specified. Then, the interval L1A is specified based on the specified distance D1A and the “distance / interval characteristics” in FIG. This specified interval L1A is the film thickness of the liquid film M at the position where the echo ratio H1A is detected (distance from the contact center S).

[When the first member 21 and the second member 22 are made of different materials]
When the first member 21 and the second member 22 are made of different materials, the distance / echo ratio characteristic indicating the relationship between the distance from the contact center S and the echo ratio H obtained by the above procedure is shown in FIG. As shown in “Distance / Echo Ratio Characteristics” (when the first member and the second member are made of different materials). In this characteristic, the echo ratio gradually decreases from the distance from the contact center S to near the contact boundary SS, and the echo ratio gradually decreases when the distance from the contact center S exceeds the vicinity of the contact boundary SS. It has increased. When the first member 21 and the second member 22 are made of different materials, for example, when the obtained echo ratio is H1AB, the control means 60 determines the echo ratio H1AB and “distance / echo ratio characteristics” in FIG. Based on (when the first member and the second member are made of different materials), the distance D1A and the distance D1B are specified. Then, the distance L1A and the distance L1B are specified based on the specified distance D1A and distance D1B and the “distance / interval characteristics” in FIG. The specified interval L1A and interval L1B are the film thicknesses of the liquid film M at the position where the echo ratio H1AB is detected (distance from the contact center S). Which of the intervals L1A and L1B is the correct film thickness? do not know. Therefore, according to the following procedure, the “distance / echo ratio characteristic” (when the first member and the second member are made of different materials) is corrected.

● [Sound pressure intensity distribution spreading downward from the focal point P of the ultrasonic waves (FIGS. 6 and 7) and the relationship between the contact surface and the sound pressure intensity distribution (FIG. 8)]
FIG. 6 shows an example of a method for measuring the sound pressure intensity distribution extending downward from the focal point P when the focal point P of the ultrasonic wave transmitted from the ultrasonic probe 40 is set on the lower surface 21 </ b> B of the first member 21. ing. The lower side of the first member 21 is filled with an ultrasonic conductive medium BA such as oil adjusted to the same acoustic impedance as the second member 22. A sound pressure intensity detecting means HP such as a hydrophone is disposed in the ultrasonic conduction medium BA. The control means 60 moves the sound pressure intensity detecting means HP to various positions (various positions in the ultrasonic conduction medium BA) with respect to the position of the focal point P, detects the sound pressure intensity at each position, and detects the sound pressure. Measure the intensity distribution. When the distribution state of the measured sound pressure intensity is shown by shape, the shape shown in the example of FIG. 7 is obtained. When the shape of the sound pressure intensity distribution state shown in FIG. 7 is cut along the ultrasonic wave transmission direction (cut along the plane including the Z axis), the shape of the cross-sectional contour is similar to a normal distribution curve. ing. The ideal focal point P is a “point”, but actually the focal point P is not a “point” but a “plane” having a predetermined diameter.

  FIG. 8 shows a virtual image diagram in plan view and side view of the contact surface between the first member 21 and the second member 22 and the sound pressure intensity distribution based on the focal point P of the ultrasonic wave. Here, the symbol VS indicates a virtual contact cylinder that is a virtual substantially cylinder positioned up to a lower surface of the second member 22 with a substantially circle that is a contact surface between the first member 21 and the second member 22 as an upper surface. Yes. Therefore, the virtual contact cylinder VS has a substantially cylindrical shape with the Z axis direction straight line ZVS passing through the contact center S as an axis, and the upper surface is a substantially circle having the contact boundary SS as an outline, and the distance from the straight line ZVS to the side surface. Is equal to the distance from the contact center S to the contact boundary SS. In addition, as shown in FIG. 7, the symbol VB is a virtual solid based on the sound pressure intensity distribution that spreads downward from the focal point P of the ultrasonic wave, and has a cross section when cut along the ultrasonic wave transmission direction. A virtual sound pressure intensity distribution solid whose contour has a normal distribution shape is shown.

In the example of FIG. 8, the focal position distance DSP, which is the distance from the contact center S to the focal point P, is the sum of the radius RVS of the virtual contact cylinder VS and the radius RVB of the approximate circle on the upper surface of the virtual sound pressure intensity distribution solid VB. Is also small (focal position distance DSP <radius RVS + radius RVB), and the virtual contact cylinder VS and the virtual sound pressure intensity distribution solid VB are superimposed at the hatched positions. Then, the solid portion of the hatched portion is set as the overlapping portion VD. Here, when the volume (Vd) of the overlapping portion VD with respect to the volume (Vb) of the virtual sound pressure intensity distribution solid VB is the overlapping volume ratio (Rr), the following (Expression 2) is established. Then, when the following (formula 2) is shown in a graph in which the horizontal axis is the distance from the contact center S and the vertical axis is the superimposed volume ratio, the “distance / volume ratio characteristic” shown in FIG. 8 is obtained.
Superposed volume ratio (Rr) = Volume of superposed part VD (Vd) / Volume of virtual sound pressure intensity distribution solid VB (Vb) (Formula 2)

The inventor believes that the overlapping portion VD has a distance from the contact center S from zero to the vicinity of the contact boundary SS in the “distance / echo ratio characteristics” in FIG. 5 (when the first member and the second member are different materials). Up to this point, it was considered that the echo ratio gradually decreased, and the correction amount (Adj) shown in the following (Equation 3) was devised. In the following correction amount (Adj), Z1 is the acoustic impedance of the first member 21, and Z2 is the acoustic impedance of the second member 22. If (Z1−Z2) / (Z1 + Z2) in (Expression 3) is the reflectance (Ref) of the ultrasonic wave on the contact surface, (Expression 3) becomes (Expression 4).
Correction amount (Adj) = [(Z1-Z2) / (Z1 + Z2)] * overlapping volume ratio (Rr) (Formula 3)
Correction amount (Adj) = Reflectance (Ref) * Overlapping volume ratio (Rr) (Formula 4)

● [Create distance / corrected echo ratio characteristics (Fig. 9)]
Then, as shown in (Equation 5) below, the corrected echo ratio (HH) is created by subtracting the correction amount in (Equation 4) from the echo ratio (H) in (Equation 1) above. Then, based on the created corrected echo ratio (HH), the “distance / corrected echo ratio characteristic” has a tendency to gradually increase as the distance from the contact center S gradually moves away from the zero position (see FIG. 9). Create This step corresponds to a distance / corrected echo ratio characteristic creation step.
Corrected echo ratio (HH)
= Echo ratio (H) -correction amount (Adj)
= Echo ratio (H) -Reflectance (Ref) * Overlapping volume ratio (Rr)
= [Measured echo intensity (h) / reference echo intensity (ho)]-[(Z1-Z2) / (Z1 + Z2)] * [volume of superimposition portion VD (Vd) / volume of virtual sound pressure intensity distribution volume VB ( Vb)] (Formula 5)

  That is, in FIG. 9, from the graph of “distance / echo ratio characteristics” (when the first member and the second member are made of different materials), “distance / superimposed volume ratio characteristics” of the virtual contact cylinder and the virtual sound pressure intensity distribution solid. By subtracting this graph, a graph of “distance / corrected echo ratio characteristics” (when the first member and the second member are made of different materials) can be obtained. In the obtained “distance / corrected echo ratio characteristics” (when the first member and the second member are made of different materials), the (corrected) echo ratio gradually increases as the distance from the contact center S increases from zero. Has a tendency. Therefore, for example, when the corrected echo ratio at an arbitrary position of the measurement object is HH1, the corrected echo ratio HH1 and the “distance / corrected echo ratio characteristic” (when the first member and the second member are made of different materials). Based on (see FIG. 9), the distance from the contact center S is specified as one of the distances D1B. Then, based on the identified distance D1B and the “distance / interval characteristics” shown in FIG. 5, the interval L1B (film thickness L1B) is identified. That is, it can be specified that the film thickness corresponding to the measured arbitrary position is the film thickness L1B.

  As described above, the film thickness of the liquid filled in at least a part of the space formed around the contact surface where the first member and the second member made of different materials are brought into contact with each other is measured. "Distance / Echo Ratio Characteristic" indicating the relationship between the distance from the contact center, which is the center of the contact surface between the first member and the second member, and the echo ratio (materials different between the first member and the second member) )), The echo ratio gradually increases as the distance from the center of contact increases from zero ["Distance / corrected echo ratio characteristics" (when the first and second members are of different materials) ] To correct. Thereby, the distance specified from the corrected echo ratio can be made one, and one film thickness can be specified from the specified distance.

  The processing procedure of the echo characteristic correction method of the present invention can be variously changed, added, and deleted without changing the gist of the present invention.

  In the description of the present embodiment, the case where the materials of the first member and the second member are different materials has been described. For example, the material of the first member includes glass and the material of the second member is steel, but the first member and the second member may be different from each other. Is not limited to glass or steel.

  The film thickness of the liquid described in the present embodiment is not limited to the film thickness of the lubricating oil, and can be applied to the measurement of the film thickness of various liquids such as water.

  In addition, the echo characteristic correction method described in the present embodiment is, for example, a bearing device (for example, the rolling element is steel, the inner ring and the outer ring are made of a material different from the rolling element (ball, roller, etc.) It can also be applied to the measurement of liquid film thickness (oil film thickness) under dynamic conditions (acting as a bearing) of an actual machine with an outer ring of ceramic or the like. Moreover, it is applicable also to the model etc. for the oil film thickness measurement of a ceramic board (1st member) and a steel ball (2nd member).

  In addition, since the echo characteristic correction method described in this embodiment can measure the liquid film thickness under dynamic conditions, the supply amount of lubricating oil, the effect of the shape of the track, and abnormality diagnosis (oil film) It can also be applied to (determination of cutting).

DESCRIPTION OF SYMBOLS 1 Ultrasonic measuring device 21 1st member 21A Surface (upper surface)
21B Back (bottom)
22 Second member 22A Surface (upper surface)
22B Back side (lower side)
40 Ultrasonic probe 51 Medium holding member 52 Seal member 71 Probe arm 72 Probe holder 60 Control means 81, 82 Base 83 Support member B, BA Ultrasonic conduction medium HP Sound pressure intensity detection means M Liquid film P Focus S Contact center SS Contact boundary VB Virtual sound pressure intensity distribution solid VD superposition part VS Virtual contact cylinder

Claims (3)

When measuring the film thickness of the liquid filled in at least a part of the space formed around the contact surface where the first member and the second member made of different materials are in contact with each other using ultrasonic waves An echo characteristic correction method for correcting an echo characteristic,
The first member has a front surface and a back surface;
The shape of the second member has a convex shape in which the surface facing the back surface of the first member has at least one curvature toward the first member,
The first member and the second member are arranged vertically so that the surface of the second member is in contact with the back surface of the first member with the first member as the upper side, and the first member and the second member At least part of the space formed around the contact surface with the liquid is filled with liquid,
An ultrasonic probe that is disposed on the surface side of the first member via an ultrasonic conduction medium and transmits an ultrasonic wave directed from the front surface to the back surface of the first member and detects a reflected wave of the transmitted ultrasonic wave; Using a control means for controlling the ultrasonic probe,
The ultrasonic wave is transmitted from the ultrasonic probe and the transmitted ultrasonic wave is reflected on the back surface of the first member, and the transmitted ultrasonic wave is transmitted to the surface of the second member. A combined reflected wave detecting step for detecting an echo intensity of the combined reflected wave synthesized with the second member surface reflected wave reflected at least from a contact center that is the center of the contact surface to a predetermined distance;
A reference echo intensity determined in advance, the second member and the liquid are excluded, and an ultrasonic wave directed from the front surface to the back surface of the first member is transmitted only in the state of the first member. An echo ratio calculating step for obtaining an echo ratio obtained by dividing the echo intensity detected in the combined reflected wave detection step with the reference echo intensity based on the echo intensity of the first member back surface reflected wave reflected on the back surface; ,
A distance / echo ratio characteristic indicating a relationship between a distance from the contact center and an echo ratio of each distance from the contact center obtained in the echo ratio calculating step, wherein the distance from the contact center is the contact ratio. The distance / echo has a tendency that the echo ratio gradually decreases until near the boundary of the surface, and the echo ratio tends to increase gradually when the distance from the contact center exceeds the vicinity of the boundary. The ratio characteristic is corrected based on the size of the contact surface and the sound pressure intensity distribution characteristic of the ultrasonic wave transmitted from the ultrasonic probe, the echo ratio from the contact center to the vicinity of the boundary, A distance / corrected echo ratio characteristic creating step for creating a distance / corrected echo ratio characteristic in which the echo ratio tends to gradually increase as the distance from the contact center increases.
Echo characteristic correction method. The echo characteristic correction method according to claim 1,
The ultrasonic wave transmitted from the ultrasonic probe can adjust the focal position, and the focal point is adjusted on the back surface of the first member,
In the distance / corrected echo ratio characteristic creating step,
The echo ratio from the contact center to the vicinity of the boundary,
A virtual contact cylinder that is a virtual substantially circular cylinder positioned up to the lower surface of the second member with the upper surface of the substantially circle that is the contact surface of the first member and the second member;
It is a virtual solid based on the sound pressure intensity distribution that spreads downward from the focal point of the ultrasonic wave that has been obtained in advance, and the shape of the profile of the cross section cut along the transmission direction of the ultrasonic wave is a normal distribution curve shape A correction amount based on the virtual sound pressure intensity distribution solid
Echo characteristic correction method. The echo characteristic correction method according to claim 2,
In the distance / corrected echo ratio characteristic creating step,
The echo ratio of each distance from the contact center from the contact center to the vicinity of the boundary,
“Echo ratio at each distance” − “Reflectivity of the ultrasonic wave at the contact surface” * “Volume of the portion where the virtual contact cylinder and the virtual sound pressure intensity distribution solid at each distance overlap / the virtual sound pressure” `` Volume of intensity distribution solid ''
Echo characteristic correction method.

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