JP5649433B2 - Wax thickness measuring apparatus and method - Google Patents

Description

  The present invention relates to a technique for measuring the thickness of a brazing material at a joint between brazed base materials.

  Conventionally, brazing is used to join metal materials, non-metal materials, or between metal materials and non-metal materials. The brazing is a joining means for joining the base materials by a wetting phenomenon without melting the base material by melting a brazing material having a melting point lower than that of the base material and using it as an adhesive. As brazing, there are brazing using a hard brazing and soldering using a soft brazing (solder). The hard solder is generally an alloy such as a gold solder, a silver solder or a brass solder.

  In Non-Patent Document 1, factors affecting the strength of brazed joints are brazing clearance (brazing material thickness = brazing thickness), brazing area, base metal strength, etc., and these factors are combined. It is described that the brazing strength is determined by acting on. FIG. 5 shows the effect of brazing strength from “the effects of brazing clearance, brazing area and base metal strength on the brazing strength of butt joints and lap joints” shown in FIG. Only the relationship of brazing clearance is extracted. As shown in FIG. 5, when the thickness of the brazing material (brazing gap) is extremely small, the joining strength (shear strength or tensile strength) is remarkably small, and the joining strength increases as the brazing material thickness increases. Has increased. However, the bonding strength peaks when the thickness of the brazing material reaches a predetermined value (T1 for the butt joint and T2 for the lap joint), and then decreases as the thickness of the brazing material increases. . Such a relationship between the joining strength and the thickness of the brazing material indicates that there is a suitable range for the thickness of the brazing material joining the brazed base materials.

  As described above, since the joint strength of the joint portion by brazing is affected by the thickness of the brazing material, it is desirable to manage the thickness of the brazing material in order to guarantee the product. Conventionally, the thickness of the brazing material joining the base materials has been measured by brazing the base material experimentally and cutting it. However, the thickness of the brazing material may vary depending on the brazing state (for example, defects). If the brazing material thickness can be measured at each brazing joint, the product can be managed with higher accuracy. It becomes possible. For this reason, a technique for non-destructively measuring the thickness of the brazing material at the brazed joint portion is desired.

  Patent Document 1 discloses a technique for measuring the film thickness of a surface coating, not the thickness of a brazing material, but measuring the film thickness non-destructively using ultrasonic waves. This technique uses a highly damped ultrasonic probe to radiate an ultrasonic pulse including a low-frequency pulse component and a high-frequency pulse component to a subject. The received signal is subjected to Fourier transform, and in the Fourier transformed data, a peak value on the low frequency side and a peak value on the high frequency side are obtained, and the film thickness of the film is measured based on a value obtained by normalizing one of them. . Here, an ultrasonic probe capable of incorporating two types of components inside one ultrasonic wave is used, and its transmission waveform has a frequency distribution of two mountains having two peaks.

Japanese Patent Laid-Open No. 3-137504

Welding Technology June 2008, pages 71-72

  Conventionally, there is no technique for nondestructively measuring the thickness of the brazing material in the brazed joint portion. Further, even if the thickness measurement method described in Patent Document 1 is applied to measure the thickness of the brazing material at the brazed joint portion, there are limitations on the measurement target. This is because the film thickness measurement method described in Patent Document 1 is based on the difference in the attenuation amount of ultrasonic waves by utilizing the characteristic that high frequency ultrasonic waves are more easily attenuated than low frequency ultrasonic waves. And measure the film thickness. For this reason, in practice, only the film thickness of a coating film having an extremely large ultrasonic attenuation can be measured as compared with the base material.

  Therefore, the present invention proposes an apparatus and a method for non-destructively measuring the thickness of the brazing material between the brazed base materials.

  A brazing thickness measuring apparatus according to the present invention is a brazing thickness measuring apparatus that measures the thickness of a brazing material between brazed base materials, and is an ultrasonic probe capable of oscillating and receiving ultrasonic waves of a plurality of frequencies. For each of the ultrasonic waves of the plurality of frequencies, the echo measuring unit that measures the echo height of the ultrasonic waves oscillated and received by the ultrasonic probe, and the ultrasonic waves of the plurality of frequencies Echo height-wax thickness information indicating the correlation between the echo height of ultrasonic waves reflected at the two joining interfaces between the base material and the brazing material (hereinafter referred to as “interface echo height”) and the thickness of the brazing material And a thickness of the brazing material to calculate the thickness of the brazing material from the plurality of interface echo heights obtained from the measured echo height using the first storage unit storing the echo and the echo height-wax thickness information And an arithmetic unit.

  Similarly, the brazing thickness measuring method according to the present invention is a brazing thickness measuring method for measuring the brazing material thickness between the brazed base metals, and for each of a plurality of ultrasonic waves, an ultrasonic probe is measured. The echo height-wax thickness information indicating the correlation between the ultrasonic echo height of the ultrasonic wave received by oscillation of the touch element and the interface echo height of the ultrasonic waves of a plurality of frequencies and the thickness of the brazing material And a step of calculating a thickness of the brazing material from the plurality of interface echo heights obtained from the measured echo height using the echo height-wax thickness information.

  In the above brazing thickness measuring apparatus and brazing thickness measuring method, ultrasonic waves of a plurality of frequencies are incident on a base material to measure the reflection echo height, and based on the obtained plurality of interface echo heights, the brazing material thickness is measured. Is measuring. Thus, according to the present invention, the thickness of the brazing material between the brazed base materials can be measured nondestructively. Moreover, since the ultrasonic attenuation is not used in measuring the thickness of the brazing material, the thickness of the brazing material can be measured even if the ultrasonic attenuation rate between the base material and the brazing material is relatively small. . Furthermore, if the physical property values of the base material and the brazing material are used, the thickness of the brazing material can be measured without using a known contrast test piece.

  In the solder thickness measuring apparatus and the solder thickness measuring method, the plurality of frequencies include at least a first frequency and a second frequency higher than the first frequency, and an ultrasonic interface echo height of the first frequency. It is preferable that the fluctuation cycle accompanying the increase in the thickness of the brazing filler metal is at least twice the fluctuation cycle accompanying the increase in the thickness of the brazing filler metal at the interface echo height of the ultrasonic wave of the second frequency.

  Alternatively, in the solder thickness measuring apparatus and the solder thickness measuring method, the plurality of frequencies include at least a first frequency and a second frequency higher than the first frequency, and the second frequency is the first frequency. It is good that it is 2 times or more.

  By defining the relationship between the frequencies of a plurality of incident ultrasonic waves as described above, it becomes easy to specify the wax thickness from the measured interface echo height.

  In the brazing thickness measuring apparatus, the echo height-brazing thickness information is created based on the plurality of frequencies, the physical property value of the base material and the physical property value of the brazing material, or in addition to experimental values. Can do. Similarly, in the brazing thickness measurement method, the step of creating the echo height-wax thickness information includes performing the experiment on the plurality of frequencies, the physical property value of the base material and the physical property value of the brazing material, or in addition thereto. The echo height-wax thickness information can be generated based on the value.

  According to the present invention, it is possible to measure the thickness of the brazing material at the brazed joint portion in a nondestructive manner. In addition, since the attenuation amount of the ultrasonic wave incident on the measurement is not used, the thickness of the brazing material can be measured even if the difference in ultrasonic attenuation amount between the base material and the brazing material is small.

It is a block diagram showing a schematic structure of an ultrasonic soldering thickness measuring device concerning an embodiment of the present invention. It is a figure explaining the kind of reflected wave which a probe receives. It is a graph showing an example of the echo height-brazing thickness curve. It is a graph showing a received waveform. It is a figure which shows the influence of the thickness of the brazing material on joining strength. It is a flowchart which shows the flow of a brazing thickness measurement process.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference symbols throughout the drawings, and redundant description thereof is omitted.

  As shown in FIG. 1, the ultrasonic brazing thickness measuring apparatus 1 according to the present embodiment includes a probe 2 while immersing a probe 2 and a subject 10 together in water according to a water immersion method. The ultrasonic wave oscillated from the incident light is incident on the base material 11 of the subject 10 and the ultrasonic wave reflected and returned from the subject 10 is measured. The ultrasonic solder thickness measuring apparatus 1 includes a probe 2, an ultrasonic transmitter / receiver 3, an A / D converter 4, an arithmetic control device 5, an input device 61, an output device 62, and a probe. 2 and a water tank 7 for immersing the subject 10 in water.

  The subject 10 is a brazing material 13 joining the brazed first base material 11 and the second base material 12. In the present embodiment, both the first base material 11 and the second base material 12 are SUS403, and the brazing material 13 is gold brazing. The first base material 11 and the second base material 12 are brazed by placing brazing using a foil-shaped brazing, and the thickness of the brazing material 13 of the joint portion 10A (hereinafter referred to as “wax thickness T Is also in the micrometer order. The thickness is a size in a direction substantially orthogonal to the joint surface.

  The probe 2 is configured to oscillate ultrasonic waves and receive reflected ultrasonic waves. However, the probe 2 is not limited to this mode as long as it can oscillate and receive a plurality of ultrasonic waves having different frequencies, and the ultrasonic probe or oscillator whose oscillation frequency can be freely changed in a certain band. It is possible to appropriately select and use an ultrasonic probe capable of changing the frequency to be changed by a plurality of values, a plurality of ultrasonic probes capable of oscillating and receiving ultrasonic waves of a certain frequency, and the like.

  The probe 2 is connected to the ultrasonic transmitter / receiver 3 by wire or wirelessly. The ultrasonic transmitter / receiver 3 includes a pulse oscillating unit 31, a receiving unit 32, and an amplifying unit 33. The pulse oscillating unit 31 transmits a pulse signal to the probe 2. The receiving unit 32 receives a detection signal (reflected wave signal) of an ultrasonic reflected wave received by the probe 2. The amplifying unit 33 amplifies the reflected wave signal with a predetermined amplification factor and transmits the amplified signal to the A / D converter 4. The A / D converter 4 digitizes the analog reflected wave signal received from the ultrasonic transceiver 3 and outputs the digital data to the arithmetic control device 5. The amplification factor of the amplification unit 33 of the ultrasonic transmitter / receiver 3 corresponds to the echo detection sensitivity. The reference sensitivity of the echo detection sensitivity is set so that the bottom surface echo height of the standard specimen is 80%.

  The arithmetic and control unit 5 includes an echo measurement function unit 50 and a solder thickness measurement function unit 70. In this embodiment, the echo measurement function unit 50 and the thickness measurement function unit 70 are provided in one arithmetic control device 5, but they may be mounted in different arithmetic control devices. The arithmetic control device 5 includes an A / D converter 4, an input device 61 such as a keyboard for inputting information to the arithmetic control device 5, and a display or printer for outputting processing results from the arithmetic control device 5. The output device 62 is connected. The arithmetic and control unit 5 is a so-called computer, and a CPU (Central Processing Unit), a program executed by the CPU, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) that stores data used for these programs in a rewritable manner. And a RAM (Random Access Memory) that temporarily stores data during program execution.

  In the arithmetic and control unit 5, the functions of the functional units constituting the arithmetic and control unit 5 are realized by executing a predetermined program by the CPU. The echo measurement function unit 50 of the arithmetic control device 5 includes an oscillation control unit 51, an echo measurement unit 52, and a storage unit 53. The brazing thickness measuring function unit 70 includes a brazing thickness calculation unit 71, a joint strength evaluation unit 72, a first storage unit 73, and a second storage unit 74. The processing contents of these functional units will be described later.

  The ultrasonic soldering thickness measuring apparatus 1 having the above configuration is not different from a commercially available ultrasonic testing equipment except for the soldering thickness measuring function unit 70 of the arithmetic and control unit 5. The ultrasonic inspection apparatus is an apparatus having a function of making an ultrasonic wave incident on a subject and measuring the intensity and position of the reflected wave, such as an ultrasonic flaw detection apparatus. Therefore, the brazing thickness measuring apparatus 1 can be configured by adding the function as the thickness measuring function unit 70 of the arithmetic and control unit 5 to the above-described known ultrasonic inspection apparatus. Since the ultrasonic inspection apparatus is well known, further detailed description is omitted.

  When performing the brazing thickness measurement of the brazed joint portion of the subject 10 using the ultrasonic brazing thickness measuring apparatus 1 having the above-described configuration, measurement conditions are input to the arithmetic control device 5 via the input device 61. The measurement conditions include data of the subject 10, sensitivity, the frequency of the first ultrasonic wave, the frequency of the second ultrasonic wave, and the like. The data of the subject 10 includes the thickness of the base materials 11 and 12 (size in the direction orthogonal to the joint surface) and the physical property values of the base materials 11 and 12 and the brazing material 13 (material, density, ultrasonic sound velocity, etc.) ). The echo detection sensitivity is determined as described above.

Here, the frequency of the first ultrasonic wave (first frequency f ₁ ) and the frequency of the second ultrasonic wave (second frequency f ₂ ) will be described in detail. FIG. 2 is a diagram for explaining the types of reflected waves received by the probe. As shown in FIG. 2, when an ultrasonic wave is incident on the subject 10 from the probe 2 perpendicular to the bonding surface, a part of the ultrasonic wave is at the bonding interface between the first base material 11 and the brazing material 13. Reflected and the remainder transmitted. The transmitted ultrasonic waves are reflected at the bonding interface between the brazing material 13 and the base material 12. For this reason, the ultrasonic wave is reflected at the two joining interfaces of the base materials 11 and 12 and the brazing material 13 and the echo height (hereinafter referred to as “interface echo h”) of the reflected wave (hereinafter also referred to as “interface echo h”) is measured. The interface echo height H ”is also affected by the interference of these waves and varies depending on the solder thickness T. In addition to the interface echo h, the reflected wave to be measured includes a surface reflected wave reflected on the surface of the first base material 11 before entering the first base material 11, the first base material 11, and the wax. There is a bottom surface reflected wave transmitted through the material 13 and the second base material 12 and reflected by the bottom surface of the second base material 12. The interface echo h can be distinguished from the surface reflected wave and the bottom reflected wave by the arrival time difference.

The transmittance r of the brazing material 13 of the ultrasonic wave perpendicularly incident between the two surfaces where the brazing material 13 is interposed from the probe 2 can be obtained by the following formula 1. In Equation 1, it is assumed that the sound pressure and the velocity are continuous at the two joining interfaces of the base materials 11 and 12 and the brazing material 13. Then, using Formula 1 and Formula 2 shown below, from the physical property values of the base materials 11 and 12 and the brazing material 13, the first frequency f ₁ or the second frequency f _2, and the intensity of the incident wave, the interface The echo height H (the intensity of the reflected wave) can be obtained.

In Equation 1, Z ₁ is the acoustic impedance of the base material 11, Z ₂ is the acoustic impedance of the base material 12, Z ₃ is the acoustic impedance of the brazing material 13, T is the brazing thickness, and k is 2π / λ (λ is the brazing material). 13 represents the wavelength). The acoustic impedance Z can be obtained from the longitudinal wave sound velocity C _L and the density ρ in the material based on the formula [Z = C _L × ρ]. In the above formula 2, r is the reflectance of the brazed part, H is the echo height of the brazed part (the intensity of the reflected wave), r ₀ is the reflectance of the comparison test piece, and H ₀ is the comparison test piece. Represents the echo height.

Graph 1 shown in FIG. 3 shows an example of an echo height-wax thickness curve showing the relationship between the interface echo height H (the maximum echo height of the interface echo h) and the braze thickness T. This echo height-wax thickness curve is obtained by adding the physical properties of the base materials 11, 12 and the brazing material 13, the first frequency f ₁ or the second frequency f ₂ , Obtained by substituting the echo height. Here, the base material is stainless steel, and the brazing material is gold brazing. In graph 1, the chain line indicates an echo height-wax thickness curve when the ultrasonic frequency is 5 MHz, and the solid line indicates an echo height-wax thickness curve when the ultrasonic frequency is 10 MHz. The echo height-wax thickness curve when the frequency is 5 MHz shows that the echo height increases from 0% to about 20% as the braze thickness T increases while the braze thickness is between 0 μm and about 180 μm. Is about 180 μm to about 360 μm, the echo height decreases from about 20% to 0% as the wax thickness T increases, and one cycle consisting of the above increase and decrease of the echo height increases the wax thickness. It repeats with it. Further, the echo height-wax thickness curve when the frequency is 10 MHz shows that the echo height increases from 0% to about 20% as the wax thickness T increases when the wax thickness is between 0 μm and about 90 μm. When the thickness T is about 90 μm to about 180 μm, the echo height decreases from about 20% to 0% as the wax thickness T increases, and one cycle consisting of the above increase and decrease of the echo height is reduced by one cycle. It repeats with the increase. One cycle of the fluctuation of the echo height-wax thickness curve when the frequency is 5 MHz is twice the cycle of the fluctuation of the echo height-wax thickness curve when the frequency is 10 MHz.

  As described above, the interface echo height H periodically varies as the wax thickness T increases, and the variation period varies depending on the frequency of the ultrasonic waves. If this characteristic is used, it is possible to specify the brazing thickness T by measuring the interface echo height H by entering a plurality of ultrasonic waves having different frequencies into the subject 10. In the present embodiment, there are two types of frequencies of ultrasonic waves incident on the subject 10, but two or more types of ultrasonic frequencies may be used. As the types of ultrasonic frequencies increase, measurement errors are less likely to occur, and the wax thickness T can be measured with higher accuracy. However, considering the structure of the probe 2 used and the measurement time, several types of ultrasonic frequencies that can be oscillated are appropriate. Note that the measured interface echo height H periodically varies with an increase in the brazing thickness T. Therefore, if one frequency is used, an error may occur in the identification of the brazing thickness T, which is not preferable. . In particular, when the change in the interface echo height H due to interference is a combination of a base material and a brazing material as small as several percent, the brazing thickness T measured as one type of ultrasonic frequency is the interface echo height. The measurement error of the height H may be greatly affected, which is not preferable. For this reason, the ultrasonic frequency must be at least two types.

Further, the first frequency f ₁ and the second frequency f _{2 of the} ultrasonic wave are determined so that the wax thickness T is thinner than the wavelength of the ultrasonic wave. The first frequency f ₁ and the second frequency f ₂ are preferably values (2T <λ) at which the wavelength λ is greater than twice the thickness T. The solder thickness T is a measurement target, but the approximate value of the solder thickness T of the subject 10 is designed. The relationship between the wavelength λ of the ultrasonic wave and the solder thickness T is determined based on the designed approximate solder thickness T.

Furthermore, as shown in the graph 1, the first frequency f ₁ and the second frequency f _{2 of the} ultrasonic wave are the other frequency in one cycle of the fluctuation of the echo height-wax thickness curve of the ultrasonic wave of one frequency. It is preferable that two or more cycles of fluctuation of the ultrasonic echo height-wax thickness curve are included. In other words, one cycle of the ultrasonic echo height-wax thickness curve fluctuation of one frequency is more than twice the one cycle of the ultrasonic echo height-wax thickness curve of the other frequency. It is preferable. More preferably, as shown in Graph 1, one cycle of the ultrasonic echo height-wax thickness curve variation of one frequency is equivalent to one cycle of the ultrasonic echo height-wax thickness curve variation of the other frequency. It is preferably twice as long as one cycle. As an example of such a combination of the first frequency f ₁ and the second frequency f ₂ , one frequency can be 5 MHz, and the other frequency can be 10 MHz, which is twice that frequency. If the other frequency is twice or more of the one frequency, the relationship between the first frequency f ₁ and the second frequency f ₂ is satisfied. Since the echo height-brazing thickness curve varies depending on the physical properties of the base materials 11 and 12 and the brazing material 13, the first frequency f ₁ and the second frequency are appropriately set according to the combination of the base materials 11 and 12 and the brazing material 13. so that the combination of the frequency f ₂ is selected. By having the above relationship between the first frequency f ₁ and the second frequency f ₂ of the ultrasonic wave, it becomes easy to specify the brazing thickness T from the plurality of measured interface echo heights H.

  Table 1 shown in the following Table 1 is an example of echo height-wax thickness information indicating the correlation between the interface echo height H and the braze thickness T of ultrasonic waves having different frequencies (5 MHz and 10 MHz). In Table 1, the column represents the interface echo height H (%) of the ultrasonic wave of 10 MHz, the row represents the interface echo height H (%) of the ultrasonic wave of 5 MHz, and the component of the matrix is the wax thickness T (μm). Represents. Referring to Table 1, for example, when the measured interface echo height H of ultrasonic waves of 10 MHz is 13% and the measured interface echo height H of ultrasonic waves of 5 MHz is 19%, the brazing thickness T is 130-160 μm.

  The echo height-wax thickness information can be created based on an echo height-wax thickness curve. As described above, the echo height-wax thickness curve changes depending on the ultrasonic frequency, the physical property values of the base materials 11 and 12, and the physical property value of the brazing material 13. The echo height-wax thickness information is created according to the combination with the material 13. The echo height-wax thickness information can be created by adding an experimental value obtained in an experiment conducted in advance to the combination of the ultrasonic frequency, the base materials 11 and 12 and the brazing material 13. The created echo height-wax thickness information is stored in the first storage unit 73 of the braze thickness measurement function unit 70 and set so as to be used in the processing of the brazing thickness calculation unit 71 described later.

Here, the flow of the brazing thickness measurement of the brazed joint portion of the subject 10 will be described with reference to FIG. As described above, the measurement conditions are input to the arithmetic and control unit 5, and after the subject 10 is submerged in the water tank 7, the probe 2 is positioned at a desired measurement point. Then, the probe 2 is operated to start the reflected echo measurement of the ultrasonic wave having the first frequency f ₁ (step S1). The oscillation control unit 51 of the arithmetic control device 5 transmits a pulse generation command including information such as the first frequency f ₁ of the ultrasonic wave to the ultrasonic transceiver 3 based on the measurement conditions. The pulse oscillating unit 31 of the ultrasonic transceiver 3 oscillates a pulse based on a pulse generation command. A pulse voltage oscillated by the pulse oscillating unit 31 of the ultrasonic transceiver 3 is applied to the probe 2 (specifically, a vibration element included in the probe 2), and the probe 2 has the first frequency f ₁ . Ultrasound (longitudinal wave) is generated. The ultrasonic wave generated from the probe 2 is incident on the first base material 11 of the subject 10 perpendicularly to the bonding surface through a medium (water) contained in the water tank 7.

The probe 2 receives (detects) the reflected wave as described above, and transmits a detection signal of the reflected wave to the receiving unit 32 of the ultrasonic transceiver 3. The reflected wave signal is amplified by the amplifying unit 33 of the ultrasonic transceiver 3, converted into digital data by the A / D converter 4, and output to the arithmetic control device 5. The echo measurement unit 52 of the arithmetic and control unit 5 processes the digital data of the reflected wave signal and measures the height of the reflected echo. The measured first reflection echo height data (reflection waveform information) is stored in the storage unit 53. The above is the flow of the ultrasonic reflected echo measurement operation of the first frequency f ₁ . Similarly, the ultrasonic measurement of the reflected echo of the second frequency f ₂ is performed by the brazing thickness measuring apparatus 1 (step S 2), and the second reflected echo height data is stored in the storage unit 53.

As described above, when the ultrasonic echo reflection measurement of the first frequency f _{1 and} the ultrasonic reflection echo measurement of the second frequency f ₂ are finished, the solder thickness calculation unit 71 of the solder thickness measurement function unit 70 performs the echo measurement. Based on the first and second reflection echo height data stored in the storage unit 53 of the function unit 50, the wax thickness T is calculated. Each reflection echo height data can be expressed as, for example, a reception waveform shown in graph 2 of FIG. The received waveform is represented on a graph in which the vertical axis indicates the height of the reflected echo and the horizontal axis indicates the beam path length (time).

The wax thickness calculation unit 71 first reads the first reflection echo height data from the storage unit 53, and determines the maximum reflection echo height of the interface echo h included in the first reflection echo height data as the first interface. acquiring echo as the height _{H 1} (step S3). For example, in the received waveform shown in graph 2 of FIG. 4, the first detected wave is a surface reflected wave, the second detected wave is an interface echo h, and the maximum reflected echo height of this interface echo h is the interface. The echo height is H. Similarly, the brazing thickness calculator 71 reads the second reflected echo height data from the storage unit 53, and determines the maximum reflected echo height of the interface echo h included in the second reflected echo height data as the second reflected echo height. obtaining a surface echo height _{H 2} (step S4).

Subsequently, the brazing thickness calculation unit 71 reads the echo height-wax thickness information from the first storage unit 73 (step S5), and refers to the echo height-brazing thickness information to determine the first interface echo height. The wax thickness T is specified from the combination of H ₁ and the second interface echo height H ₂ (step S6). With the above flow, the calculated wax thickness T can be output to the output device 62 such as a display, for example.

  Next, the bonding strength evaluation unit 72 calculates the bonding strength of the brazing based on the calculated brazing thickness T. The bonding strength-wax thickness information indicating the correlation between the bonding strength and the brazing thickness T is stored in the second storage unit 74 and is set to be used in the processing of the bonding strength evaluation unit 72. The relationship between the brazing joint strength and the brazing thickness T is determined by the combination of the base materials 11 and 12 and the brazing material 13, the joining area, and the brazing thickness T. Therefore, the bonding strength-brazing thickness information is created by determining the combination of the base materials 11 and 12 and the brazing material 13 and the bonding area, and obtaining the relationship between the bonding strength and the brazing thickness T at this time experimentally or theoretically. Has been. The bonding strength-brazing thickness information is, for example, the relationship between the bonding strength (shear strength or tensile strength) and the brazing thickness T (brazing gap) as shown in FIG. In FIG. 5, the tensile strength in the case of the butt joint shown on the vertical axis or the shear strength in the case of the lap joint corresponds to the bonding strength, and the brazing clearance shown on the horizontal axis corresponds to the brazing thickness T. doing.

  The joint strength evaluation unit 72 reads the joint strength-wax thickness information from the second storage unit 74 (step S7), and refers to the joint strength-brax thickness information to identify the joint strength from the calculated braze thickness T ( Step S8). The joint strength calculated in this way can be output so as to be displayed together with the wax thickness T on an output device 62 such as a display, for example.

  Further, the bonding strength evaluation unit 72 evaluates the bonding quality from the calculated bonding strength. For example, as shown in FIG. 5, a certain threshold value α is set for the bonding strength, and a good bonding range and a poor bonding range are determined with the threshold value α as a boundary. That is, the range in which the bonding strength is equal to or higher than the threshold value α is a good bonding range, and the range in which the bonding strength is less than the threshold value α is a poor bonding range. This threshold value α may be included in the joint strength-wax thickness information stored in the second storage unit 74, or may be input as one of the measurement conditions by the input device 61 for each measurement.

  The bonding strength evaluation unit 72 compares the calculated bonding strength with the threshold value α (step S9), and evaluates that the bonding strength is good when the bonding strength is equal to or higher than the threshold value α (step S10). If it is less than the threshold value α, it is evaluated as a bonding failure (step S11). The evaluation result of good or bad joining can be output so as to be displayed together with the brazing thickness T and the joining strength on an output device 62 such as a display.

  As described above, in the solder thickness measuring method using the solder thickness measuring apparatus 1 according to the present embodiment, echo height-wax thickness information indicating the correlation between the interface echo height H and the thickness of the brazing material 13 is created in advance. In addition, for each of the ultrasonic waves having a plurality of frequencies, the height of the reflected echo of the ultrasonic wave oscillated and received by the probe 2 is measured (steps S1 and S2), and a plurality obtained from the measured reflected echo height. The thickness of the brazing material 13 is calculated from the interface echo height H (steps S3, 4, 5, 6). In this way, the thickness of the brazing material between the non-destructive brazed base materials can be measured. Moreover, since the ultrasonic attenuation is not used in measuring the thickness of the brazing material, the thickness of the brazing material can be measured even if the ultrasonic attenuation rate between the base material and the brazing material is relatively small. . Furthermore, if the physical property values of the base material and the brazing material are used, the thickness of the brazing material can be measured without using a known contrast test piece.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. is there.

For example, in the above-described embodiment, the ultrasonic reflected echo measurement operation of the second frequency f ₂ is performed after the ultrasonic reflected echo measurement operation of the first frequency f ₁ is performed. Is not limited to this. For example, an ultrasonic wave of the first frequency f _{1 and} an ultrasonic wave of the second frequency f ₂ are oscillated at a predetermined interval to perform reflection echo measurement to obtain one reflection echo height data and one reflection. The first interface echo height H ₁ and the second interface echo height H ₂ can also be obtained from the echo height data. That is, the means and method for reflection echo measurement are not limited to the above-described embodiment as long as they can acquire the interface echo heights of ultrasonic waves of different types.

  In the above-described embodiment, the ultrasonic soldering thickness measurement apparatus 1 employs the total immersion method in which the probe and the subject are submerged. You may employ | adopt the local water immersion method which interposes water locally only between a touch element. Further, although it is desirable to use the water immersion method in order to perform flaw detection with high definition and little error, the water immersion method may not be used depending on the condition of the subject 10.

  Furthermore, in the above-described embodiment, the probe 2 provided in the ultrasonic solder thickness measuring apparatus 1 is a point focusing probe. However, instead of this, other types of probes can be used.

  In the above-described embodiment, the brazing thickness T measured by the brazing thickness measuring device 1 is used for evaluating the bonding strength between the base materials 11 and 12, but the brazing thickness T can be used for other purposes. . For example, the measured brazing thickness T can be used for ultrasonic flaw detection of the brazing material 13. When ultrasonic flaw detection is performed for a defect in the brazing material 13, the ultrasonic wave is incident on the subject 10, and the obtained reflection echo height is compared with a threshold value to determine the presence or absence of the defect. The threshold value at this time can be determined based on the thickness of the brazing material.

  The brazing thickness that is a measurement target of the ultrasonic brazing thickness measuring apparatus 1 is not limited to the brazing thickness T of the brazing material 13 between the brazed base materials 11 and 12. According to the brazing thickness measuring apparatus and method according to the present invention, the thickness of the brazing material (solder) between the soldered base materials can also be measured. Furthermore, according to the brazing thickness measuring apparatus and method according to the present invention, when there is a minute gap filled with a medium such as water between the base materials, the size of the minute gap can also be measured.

  The present invention is useful for measuring the thickness of a brazing material between brazed base materials. Furthermore, by applying the present invention, when there is a minute gap filled with a medium such as water between the base materials, the size of the minute gap can be measured.

DESCRIPTION OF SYMBOLS 1 Ultrasonic brazing | wax thickness measuring apparatus 2 Probe 3 Ultrasonic transmitter / receiver 4 A / D converter 5 Arithmetic controller 7 Water tank 10 Subject 11, 12 Base material 13 Brazing material 50 Echo measurement function part 51 Oscillation control part 52 Echo measurement unit 53 Storage unit 61 Input device 62 Output device 70 Thickness measurement function unit 71 Brazing thickness calculation unit 72 Bond strength evaluation unit 73 First storage unit 74 Second storage unit

Claims (8)

A brazing thickness measuring device for measuring a brazing material thickness between brazed base materials,
An ultrasonic probe capable of oscillating and receiving ultrasonic waves of multiple frequencies;
For each of the ultrasonic waves of the plurality of frequencies, an echo measurement unit that measures the echo height of the ultrasonic wave that is received by the ultrasonic probe being oscillated,
Stores echo height-wax thickness information indicating the correlation between the ultrasonic interface echo height reflected by two joint interfaces between the base material and the brazing material of the ultrasonic waves of the plurality of frequencies and the brazing material thickness. The first storage unit
A brazing thickness measuring device comprising: a brazing thickness calculation unit that calculates the brazing material thickness from the plurality of interface echo heights obtained from the measured echo height using the echo height-brazing thickness information .   The plurality of frequencies include at least a first frequency and a second frequency that is higher than the first frequency, and a fluctuation cycle associated with an increase in the thickness of the brazing filler metal at the ultrasonic interface echo height of the first frequency. The solder thickness measuring device according to claim 1, wherein the thickness of the interface echo height of the ultrasonic wave of the second frequency is at least twice the fluctuation cycle accompanying the increase in the thickness of the brazing filler metal.   2. The wax thickness according to claim 1, wherein the plurality of frequencies includes at least a first frequency and a second frequency that is higher than the first frequency, and the second frequency is at least twice the first frequency. measuring device.   The echo height-brazing thickness information is based on the plurality of frequencies, the physical property value of the base material and the physical property value of the brazing material, or in addition to these, an experimental value. The solder thickness measuring apparatus according to one item. A brazing thickness measuring method for measuring a brazing material thickness between brazed base materials,
Measuring the echo height of the ultrasonic wave received and oscillated by the ultrasonic probe for each of the ultrasonic waves of a plurality of frequencies;
Creating echo height-wax thickness information indicative of the correlation between the interface echo height of ultrasonics at multiple frequencies and the thickness of the brazing material;
Calculating the thickness of the brazing material from the plurality of interface echo heights obtained from the measured echo height using the echo height-wax thickness information.   The plurality of frequencies include at least a first frequency and a second frequency that is higher than the first frequency, and a fluctuation cycle associated with an increase in the thickness of the brazing filler metal at the ultrasonic interface echo height of the first frequency. The solder thickness measuring method according to claim 5, wherein the ultrasonic wave has an interface echo height of the second frequency at least twice as long as a fluctuation cycle associated with an increase in the thickness of the brazing material.   The wax thickness according to claim 5, wherein the plurality of frequencies include at least a first frequency and a second frequency higher than the first frequency, and the second frequency is at least twice the first frequency. Measuring method.   The step of creating the echo height-wax thickness information includes the step of creating the echo height-wax based on the plurality of frequencies, the physical property value of the base material and the physical property value of the brazing material, or in addition to these experimental values. The solder thickness measuring method according to any one of claims 5 to 7, wherein the thickness information is created.

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