JP4108550B2 - Measurement method of residual thickness - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin member for an airbag apparatus that has a tear line that is close enough to make contact with the side surfaces, and the side surfaces are not joined to each other, and in particular, the resin member that remains after the formation of the tear line. The present invention relates to a measurement method for measuring the thickness of a film using ultrasonic waves.
[0002]
[Prior art]
A resin member such as an instrument panel provided so as to cover an airbag device for an automobile needs to be provided with a groove called a tear line on its back surface so that it is easily broken when the airbag is deployed. Yes. During the molding process, the tear line is formed by inserting a blade (groove forming member) within a range not penetrating the resin material in the mold and removing the inserted blade during cooling of the resin material. However, in this prior art, there is a problem that a protrusion is generated in a portion where the groove of the surface of the resin member where the groove is not formed, and the appearance is impaired. Therefore, in order to reduce the degree of the bulge, a technique has been developed in which the inserted groove forming member is pulled out during the pressure holding process at an earlier stage than the cooling process (Patent Document 1). As a result, the side surfaces are close enough to almost come into contact with each other, and a groove (tear line) in which the side surfaces are not joined to each other can be formed. The problem of being solved.
[0003]
Various methods other than the above method have been proposed as a method for forming a tear line. For example, a method of forming a recess with a laser beam on the back side of a resin member (Patent Document 2), or a large number of minute through holes There is known a method (Patent Document 3) or the like for drilling a wire in a line shape.
[0004]
It is an extremely important issue to ensure the processing thickness of the tear line formed in this way to be a constant thickness, and various measures have been taken for the measurement.
[0005]
For a tear line having a shape as shown in FIG. 12, for example, a method of measuring the depth of a tear line with a depth gauge or the like by inserting a needle probe into the space W of the tear line, or from the opening end side of the tear line A method of measuring the depth of the tear line with a laser displacement meter by irradiating a laser, or a method of measuring an unprocessed thickness by transmitting an infrared ray and transmitting the infrared ray is known. Further, for a tear line formed by a fine through hole as described in Patent Document 3, a method of detecting the shape of the through hole using transmitted light is disclosed.
[0006]
[Patent Document 1]
Japanese Patent Application No. 2002-341731
[Patent Document 2]
JP-A-8-282420
[Patent Document 3]
JP 2000-238603 A
[0007]
[Problems to be solved by the invention]
However, any of these methods is possible because the tear line has a space (hereinafter referred to as a measurement space) in which a needle probe can be inserted or laser light can be irradiated. Means. However, the side surfaces are so close that they almost come into contact with each other, and the side surfaces are not joined to each other, that is, it cannot be applied to the measurement of the processing remaining thickness of the tear line having no measurement space. In addition, there is no known method for measuring the processing remaining thickness of a tear line that does not have such a measurement space.
[0008]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for easily and accurately measuring a processing remaining thickness of a resin member having a tear line having no measurement space.
[0009]
[Means for Solving the Problems]
In the method for measuring a processing remaining thickness according to the present invention, a tear line that is broken by the pressure of an inflating airbag is formed on a resin member provided so as to cover an airbag device, and the remaining portion after the formation of the tear line is left. The thickness of the resin member (hereinafter referred to as the remaining processing thickness) Using ultrasound taking measurement Measurement of processing thickness In the method The tear line is Tier lines that are so close that the side surfaces are almost in contact with each other, and the side surfaces are not joined to each other On the surface of the resin member where the tear line is not open, the probe that receives and transmits ultrasonic waves is moved so as to be orthogonal to the tear line, and the detection position and waveform of the reflected wave are detected as sound wave data. As a data sampling process that continuously captures and stores in the first data file (D1), and in the collected sound wave data, there is a reflected wave having a peak value of a predetermined level or more within the inspection range for determining the processing remaining thickness. And a data analysis step of storing in the second data file (D2) only sound wave data having no waveform exceeding a predetermined peak value within a plate thickness inspection range in which the plate thickness of the resin member is detected; Among the sound wave data stored in the data file (D2), the sound wave data whose reflected wave detection position is the shallowest from the surface of the resin member is selected, and the detection position of the reflected wave in this sound wave data is detected. Yusuke and data selection step of the alignment of the machining residual thickness, the adequacy determining step of determining whether the machining residual thickness which is selected is in the preset adequate range, the It is characterized by that.
[0014]
There are two methods for detecting the peak position of the waveform, and it is desirable to select in advance when inputting the initial conditions. One is a method in which the first peak position that exceeds a predetermined level within the sonic data inspection range is set as the detection position, and the second is the highest peak value that exceeds the predetermined level within the sonic data inspection range. In this method, the peak position shown is the detection position.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
A resin member having a tear line that does not have a measurement space according to the method for measuring a remaining working thickness of the present invention is formed as follows.
[0016]
FIG. 10 is a diagram illustrating an example of a resin member manufacturing apparatus in a cross-section of the main part.
[0017]
The manufacturing apparatus 20 includes a first mold 21 on the left side, a second mold 22 on the right side, a hydraulic cylinder 23 housed in the first mold 21, and a control device 24 that drives the hydraulic cylinder 23. And a shaft 25 connected to the hydraulic cylinder 23, blades 30, 32, 34 (hereinafter simply referred to as the blade 30) provided at the tip of the shaft 25. Further, a cavity 27 is formed between the first mold 21 and the second mold 22 in accordance with the shape of the resin member.
[0018]
First, a resin having fluidity is injected into the cavity 27 by an injection machine. In this injection process, about 95% of the total resin amount of the finished resin member is injected, and the remaining 5% of the resin is injected in the next pressure holding process.
[0019]
In the pressure holding process, the resin is injected into the cavity 27 little by little. As a result, pressure is applied to the resin in the cavity 27 and deformation of the resin surface that is solidified is suppressed. In the pressure holding step, about 5% of the total resin amount of the resin member is injected over 3 to 7 seconds.
[0020]
During the pressure holding process, the hydraulic cylinder 23 is turned on, the shaft 25 moves in the D1 direction, and the blade 30 is inserted into the resin (that is, the blade 30 enters the cavity 27). The blade 30 is held in the resin for a predetermined time, but is extracted from the resin before the pressure holding step is completed, and pressure is applied to the resin for a while after the blade 30 is further removed. When the blade 30 is removed, a groove having the same width as the blade 30 is formed in the resin. However, since pressure is further applied to the resin after the blade 30 is pulled out, the width of the groove formed in the resin is narrowed, and the side surfaces defining the groove may contact each other. Since the blade 30 is cooled, the portion in contact with the resin blade 30 (side surface defining the groove) quickly solidifies. For this reason, even if the side surfaces that define the grooves come into contact with each other by applying pressure, they are not joined.
[0021]
By leaving the resin in the cavity 27 for a while after the pressure holding step is completed, the resin is cooled and solidified. After the cooling step, the second mold 22 is opened and the resin member in the cavity 27 is taken out. Thereby, the resin member in which the portion into which the blade 30 is inserted becomes a groove (tear line) is completed. A cross section is shown in FIG.
[0022]
In FIG. 11, the tear line TL is formed so as to open to the bottom surface 12 side of the resin member so that the side surfaces thereof are substantially in contact with each other, and no bulge is observed in the portion 45 of the tear line on the surface 11 of the resin member.
[0023]
By the above method, a resin member having a very good appearance and a very excellent tear line can be obtained.
[0024]
The present invention is an invention relating to a method for measuring a remaining working thickness of a resin member that does not have a measurement space in a tear line formed as described above.
[0025]
The tear lines are so close that the side surfaces defining the line are almost in contact with each other, and the side surfaces are not joined to each other. Accordingly, the depth of the groove portion of the tear line cannot be directly measured by inserting a needle probe or using a laser beam. Therefore, in the present invention, ultrasonic waves are used. That is, the processing residual thickness of the resin member is to be measured by irradiating ultrasonic waves from the surface of the resin member on the side where the tear line is not formed and detecting the reflected wave at the tear line.
[0026]
FIG. 1 schematically shows the ultrasonic measurement method of the remaining thickness of processing according to the present invention and the obtained sound wave data.
[0027]
In the present invention, an ultrasonic wave is incident from the surface 11 side of the resin member 10 in the thickness direction of the resin member 10 with an ultrasonic transmitter (hereinafter referred to as a probe P), and the sound wave data D of the obtained reflected wave is obtained. This is a method for measuring the remaining processing thickness t of the resin member 10 having the tear line TL, and determining pass / fail.
[0028]
When the ultrasonic wave emitted from the probe P is applied to the resin member 10, the ultrasonic wave is reflected by the surface 11 and returns to the probe P (hereinafter, the reflected wave from the surface is referred to as a surface echo). On the other hand, at the same time, ultrasonic vibration occurs on the surface on which the ultrasonic wave is incident, and the vibration propagates into the resin member 10. If there is no tear line at the position where ultrasonic waves are incident on the resin member 10 (on the dotted line L), the transmitted ultrasonic vibration is transmitted to the bottom surface 12 of the resin member 10 and then reflected by the bottom surface 12 to be reflected in the resin member 10. In the opposite direction, returns toward the surface 11 of the resin member 10, and returns to the probe P again (hereinafter, this reflected wave is referred to as a bottom echo).
[0029]
In a portion where the tear line TL is formed in the resin member 10, the ultrasonic wave incident on the resin member 10 is reflected by the tear line TL, returns toward the surface 11 of the resin member 10, and returns to the probe P again. Return (hereinafter referred to as tear line echo).
[0030]
The sound wave data D of the reflected wave obtained corresponding to the cross section of the resin member 10 is schematically shown on the right side of FIG. In the sound wave data D, the vertical axis represents time, and the horizontal axis represents the peak value. 15 is a surface echo reflected by the surface 11 of the resin member 10, T is a tear line echo reflected by the tear line TL, and 17 is a bottom surface echo reflected by the bottom surface 12 of the resin member. The time on the vertical axis is the time from when the ultrasonic wave is transmitted from the probe, propagates through the resin member, is reflected at the tear line or the bottom surface, and reaches the probe that is the ultrasonic receiver again. . Therefore, if this time is multiplied by the speed at which the ultrasonic wave propagates through the resin member to halve, the distance to the ultrasonic wave reflection target can be obtained. Therefore, the vertical axis may be the distance (depth).
[0031]
The embodiment of the present invention will be described in detail with reference to the flowchart of FIG. 2 as an example.
[0032]
First, initial conditions necessary for analyzing sound wave data are input (step S10). The initial conditions to be entered are the inspection range for inspecting the remaining processing thickness, the determination level for discriminating sound waves exceeding a certain intensity within this inspection range, the plate thickness inspection range for detecting the plate thickness of the resin member, the plate thickness These include a plate thickness determination level for determining the presence or absence of a bottom surface echo in the inspection range, and a pass range for determining pass / fail of the remaining processing thickness.
[0033]
Next, in step S11, the probe is scanned about 5 mm while pressing the measurement start switch, and the sound wave data is taken in and stored in the data file D1. Note that the collection of sound wave data is performed through the measurement preparation step of S00. In the measurement preparation step S00, first, a resin member which is the first subject is set on a measurement table. At this time, the resin member is set with the open surface of the tear line facing downward. Next, a contact medium such as water is applied to the measurement site of the resin member with a spray, a brush, or a dropper, and the probe is brought into contact with the surface of the resin member so as not to be lifted through the contact medium. In order to find the measurement site quickly and accurately, it is preferable to use a template or the like in which measurement positions are defined in advance. Steps S00 and S11 and the data file D1 are the data collection process of the present invention.
[0034]
Steps S12 to S14 are steps for sequentially analyzing the sound wave data filed in D1. First, the sound wave data No. in the data file D1. The analysis is started from 1 (S12). Step S13 is a step of determining whether or not there is a tear line echo exceeding a predetermined determination level within the initially input inspection range. As a result of the determination, if a tear line echo exceeding a predetermined determination level is recognized (YES), the process proceeds to the next step S14 and the analysis is continued. However, if no tear line echo exceeding the predetermined judgment level is recognized (NO), the sound wave data No. 1 is stopped, the process returns to step 12 and the sound wave data No. 2 is extracted and the sound wave data No. Analysis of 2 is started.
[0035]
Step S14 is a step of determining whether or not there is a bottom echo exceeding a predetermined level within the plate thickness inspection range of the resin member. Here, when the bottom echo is not recognized (NO), this data is temporarily stored in the data file D2. If a bottom echo exceeding a predetermined level is recognized (YES), the analysis of this data is stopped here, and the process returns to S12, the next sound wave data is extracted from the data file D1, and new sound wave data Start the analysis.
[0036]
Step S13 and step S14 are the first requirements in the present invention. The aim of the first requirement is to prevent erroneous detection of a surface echo as a tear line echo when a surface echo having a level higher than a predetermined determination level has shifted to the inspection range for some reason. There is. That is, in the analysis of the sound wave only in the inspection range (S13), the shifted surface echo and the tear line echo cannot be distinguished. Therefore, in step S14, the presence or absence of the bottom surface echo is confirmed. Even if a waveform exceeding a predetermined level is detected in the inspection range, if the bottom surface echo is recognized in the plate thickness inspection range, this waveform is due to the surface echo. Judge that it is not a line echo. The reason why the surface echo shifts to the inspection range is that the probe is lifted from the surface of the resin member due to improper pressing of the probe, unevenness or distortion of the surface of the resin member or adhesion of foreign matter, that is, the probe. When the contact between the touch element and the resin member surface is weak, it is considered that the range of the dead zone is extended and the surface echo shifts to the inspection range.
[0037]
In step S15, it is confirmed that the above analysis has been completed for all the sound wave data stored in the data file D1. If there is analysis omission data (NO), the process returns to step S12 to continue analysis on the analysis omission data. Steps S12 to S15 and creation of the data file D2 correspond to the data analysis step of the present invention.
[0038]
As a result of the above analysis, a tear line echo having a peak value equal to or higher than a predetermined determination level is detected in the inspection range in the data file D2, and no bottom echo is recognized, that is, the first requirement is satisfied. Only sound wave data is stored. In step S16, the optimum data is selected as the remaining processing thickness of the resin member from these sound wave data. That is, in this step, the data that satisfies the second requirement is selected from the sound wave data stored in the data file D2, where the peak detection position of the tear line echo is at the shallowest position from the resin member surface. Step S16 is the data selection step of the present invention.
[0039]
Step S17 is a step of determining whether or not the detection position of the tear line echo selected in step S16 is within a preset acceptable range of the remaining machining thickness. If it is within the acceptable range, “pass” is displayed on the display means such as a display simultaneously with the measured value of the remaining machining thickness (the detection position of the tear line echo) (step S18). If the measured value is out of the acceptable range, “Fail” is displayed on the display means such as a display at the same time as the measured value of the remaining machining thickness (step S19). Steps S17 to S19 are pass / fail determination steps.
[0040]
As described above, the pass / fail determination is made by measuring the processing remaining thickness of one tear line. However, in practice, the position of measuring the processing remaining thickness of the tear line for one resin member is not limited to one. Usually, there are a plurality of locations. For example, in a resin member in which a “day” -shaped tear line as shown in FIG. 3 is formed, at least one place on each side of e, f, g, h, i in FIG. It is desirable to measure the remaining thickness. As described above, when the processing remaining thickness is measured for a plurality of tear lines, the quality of the tear line of the resin member is not guaranteed unless the measured values pass at all the places. Therefore, the pass / fail determination of the resin member may be determined to be acceptable only after the processing remaining thickness of all the tear lines formed on the resin member is determined to be acceptable. However, if a failure is recognized even at one location, it goes without saying that the resin member is rejected with respect to the processing thickness of the tear line. Thus, when a rejected product is detected, it is important to immediately stop the production line of the resin member and investigate the cause.
[0041]
【Example】
The present invention will be described in more detail by taking as an example the measurement of the remaining processing thickness t of a resin member having a tear line TL formed obliquely with respect to the resin member surface as shown in FIG.
[0042]
Arrows A to E on the surface of the resin member indicate respective measurement positions on the ultrasonic probe. Each sound wave data obtained at each measurement position is shown in FIGS.
[0043]
First, the sound wave data will be described with reference to FIG. FIG. 5 shows sound wave data at the position A on the surface of the resin member. The vertical axis represents the intensity of the sound wave (echo), and the horizontal axis represents the distance (time). Here, 15 is a surface echo. In addition, A is the surface of the resin member, and the range of ILO where surface echo is recognized is a dead zone directly below the surface that cannot be identified even if there is a tear line echo mixed in between. This dead zone immediately below the surface was 0.2 mm from the surface of the resin member in this example. Between Roni is the inspection range for analyzing the tear line echo, and only the tear line echo detected during this period is analyzed. In this embodiment, the inspection range is within 0.8 μsec after the surface echo attenuation, which corresponds to a depth range of 0.3 to 0.8 mm from the surface of the resin member.
[0044]
G1 is a determination level for determining whether the waveform detected in the inspection range is a tear line echo based on the strength of the waveform. That is, if the highest part of this waveform is higher than the determination level G1, it is a tear line echo, and if it is lower than G1, it is determined not to be a tear line echo. Here, “haha ′” is the inspection pass range of the remaining processing thickness, and in this example, it was set to 0.3 to 0.6 mm.
[0045]
In addition, considering the variation in the thickness of the resin member, the range in which the bottom echo appears is defined as the plate thickness inspection range of Hohe, the determination level G2 is set, and a waveform having an intensity higher than G2 is defined as the bottom echo. I decided to judge. In the present example, the plate thickness inspection range was 2.4 to 2.6 mm.
[0046]
At the measurement position A, no abnormality such as a tear line or other internal defect is recognized from the surface to the bottom surface of the resin member. It was only. Therefore, the sound wave data a is not stored in the data file D2.
[0047]
FIG. 6 is the sound wave data b obtained at the measurement position B. Here, the measurement sound wave T is recognized between nihos other than the inspection range and the plate thickness inspection range. This is a sound wave reflected by the tear line TL, and indicates that there is a tear line at a depth of Tb from the surface. However, since the range of Niho is not the inspection range, even if a tear line echo is recognized here, the analysis process determines that there is no tear line echo and the analysis is interrupted, and this waveform data b is stored in the data file D2. Not stored. In addition, if a tear line exists in the middle of the bottom surface of the resin member, the bottom surface echo 17 as shown in FIG. 5 is not recognized because the sound wave does not reach the bottom surface of the resin member due to the tear line.
[0048]
FIG. 7 shows the sound wave data c obtained at the measurement position C. Here, the measurement sound wave T is recognized within the inspection range (between Roni). T is a tear line echo reflected by the tear line TL, and indicates that there is a tear line at a depth of Tc from the surface. The tear line echo is in the inspection range, and the intensity level is higher than the determination level G1, and further, the bottom surface echo is not recognized within the plate thickness inspection range (between hoges). Stored in D2.
[0049]
FIG. 8 shows sound wave data d obtained at the measurement position D. Here, the measurement sound wave T is recognized between the two. T is a tear line echo reflected from the bottom (H in FIG. 4) of the tear line TL, and indicates that there is a tear line at a depth of Td from the surface. Haha 'is within the inspection range and within the acceptable range. Further, T indicates a value higher than G1, and no bottom echo is recognized, so that the sound wave data d is stored in the data file D2.
[0050]
FIG. 9 shows sound wave data e obtained at the measurement position E. At this position of the resin member, no tear line or other internal defects are recognized, so that the sound wave data is only the surface echo 15 and the bottom surface echo 17. Therefore, the analysis may be completed after confirming that there is no measurement sound wave in the inspection range (between lojas).
[0051]
However, in the sound wave data e, the attenuation of the surface echo 15 is delayed and a part S of the surface echo 15 is shifted to the inspection range. Furthermore, since the intensity of the surface echo S is higher than the determination level G1, it is impossible to distinguish the surface echo from the tear line echo as it is.
[0052]
However, in the present invention, it is checked whether or not a bottom echo is recognized in the plate thickness inspection range (hoge) (step S14 in the flowchart of FIG. 2). S is determined not to be a tear line echo even if detected within the inspection range. Therefore, the sound wave data e is not stored in the data file D2.
[0053]
As a result of analyzing the five sound wave data of a to e, sound wave data c and d are stored in the data file D2. In these two data, the height (intensity) of the tear line echo is the same, but the detection position of the tear line echo is different, and the sound wave data d shows a shallower (smaller) value from the resin member surface. Therefore, in this embodiment, the sound wave data d is selected as the data of the remaining processing thickness.
[0054]
The tear line echo T of the sound wave data d was recognized within the acceptable range (between ha ha '), and the peak T of the waveform was detected at a position Td (actually 0.5 mm) from the surface of the resin member. Therefore, the processing remaining thickness of the tear line of this resin member is 0.5 mm, and can be determined to be “pass” with respect to the inspection standard (0.3 to 0.6 mm). However, the actual resin member needs to be measured at a plurality of positions as described above, and it is needless to say that in order to guarantee the remaining processing thickness of the resin member, all of the resin members must be “passed”. .
[0055]
The processing remaining thickness measuring method of the present invention is an inspection of the processing remaining thickness by scanning the ultrasonic probe with a robot and linking the control of the robot with the control of the ultrasonic transmission device and the pass / fail judgment. Judgment work can be unmanned.
[0056]
Further, the measurement method of the present invention can be applied to the measurement of the remaining working thickness after the formation of the tear line having the measurement space of the prior art.
[0057]
【The invention's effect】
According to the method for measuring the remaining thickness of processing according to the present invention, since measurement is performed using ultrasonic waves, the remaining processing thickness is quickly and accurately measured without destroying the resin member, and the acceptance / rejection is judged based on the reference value. It is possible to guarantee all products in a non-destructive manner. In the present invention, it is possible to prevent erroneous detection of the surface echo as a tear line echo because the obtained sound wave data is determined by checking the presence or absence of the bottom surface echo.
[0058]
In addition, the processing thickness measurement method of the present invention can unmanned inspection determination work by linking an ultrasonic measurement device or the like with a robot, which can greatly contribute to the improvement of productivity of inspection determination work. it can.
[0059]
The method for measuring the remaining processing thickness of the present invention is suitable not only for instrument panels of automobiles but also for nondestructive inspection of the remaining processing thickness after forming a tear line of a resin member used for steering, garnish, knee airbags, etc. Available to:
[Brief description of the drawings]
FIG. 1 is an explanatory view schematically showing a method of measuring a processing thickness of a tear line by ultrasonic waves according to the present invention and sound wave data obtained.
FIG. 2 is a flowchart showing a procedure for determining a processing remaining thickness by determining a tear line echo according to the present invention.
FIG. 3 is a diagram illustrating an example of a measurement point of a tear line.
FIG. 4 is a diagram showing a sampling position of sound wave data obtained in the example.
FIG. 5 is a sound wave data of a portion where a tear line echo is not recognized.
FIG. 6 is sound wave data in which a tear line echo is detected outside the inspection range.
FIG. 7 is sound wave data in which a tear line echo is detected within an examination range.
FIG. 8 is sound wave data in which a tear line echo is detected within an acceptable range.
FIG. 9 is sound wave data detected by detecting a surface echo shifted within an inspection range.
FIG. 10 is a cross-sectional view of an essential part showing an apparatus for producing a resin member having a tear line that does not have a measurement space as an object of the present invention.
FIG. 11 is a cross-sectional view illustrating a tear line having no measurement space.
FIG. 12 is a schematic cross-sectional view of a tear line according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10: Resin member 15: Surface echo 17: Bottom surface echo 20: Resin member manufacturing apparatus 21: 1st shaping | molding die 22: 2nd shaping | molding die 23: Hydraulic cylinder 25: Shaft 27: Cavity 30, 32, 34: Blade 45: Raising D: Sound wave data P: Probe T: Tear line echo TL: Tear line W: Measurement space t: Remaining thickness

Claims (1)

A tear line that is broken by the pressure of the inflating airbag is formed in a resin member provided to cover the airbag device, and the thickness of the resin member remaining after the formation of the tear line (hereinafter referred to as processing remaining thickness) In the method of measuring the remaining machining thickness using ultrasonic waves ,
The tear line is a tear line that is so close that the side surfaces are almost in contact with each other, and the side surfaces are not joined to each other ,
The probe that receives and transmits ultrasonic waves on the surface of the resin member that is not open on the tear line is moved so as to be orthogonal to the tear line, and the detection position and waveform of the reflected wave are used as sound wave data. A data collection step of continuously capturing and storing in the first data file (D1);
In the collected sound wave data, there is a reflected wave having a crest value equal to or higher than a predetermined level within an inspection range for determining the processing remaining thickness, and the predetermined thickness within the plate thickness inspection range where the thickness of the resin member is detected. A data analysis step of storing only sound wave data having no waveform exceeding the peak value of the level in the second data file (D2);
Among the sound wave data stored in the second data file (D2), the sound wave data in which the detection position of the reflected wave is at the shallowest position from the surface of the resin member is selected, and the reflected wave in the sound wave data is selected. A data selection step in which the detection position is the processing remaining thickness of the tear line; and
Measurement method for processing residual thickness, characterized in Rukoto that Yusuke and adequacy determining step of determining whether the selected said processing residual thickness is in the preset adequate range, the.

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