JP5080928B2 - Friction stir welding system and friction stir welding method - Google Patents

Description

  The present invention relates to a friction stir welding system and a friction stir welding method.

  Friction stir welding (FSW) is known as a method for joining metal materials. In the friction stir welding, the metal materials to be joined are opposed to each other at the joint. And the probe provided in the front-end | tip of a rotary tool is pushed in into a junction part, is rotated, and two metal materials are joined by plastic flow by friction heat.

As a technique related to the friction stir welding method, for example, there is a friction stir welding method described in Patent Document 1. In this conventional friction stir welding method, the time when the resistance force applied to the rotating tool from the object to be joined becomes maximum is regarded as the time when the probe is completely pushed into the joint, and the rotating tool moves at this time. Like to start.
JP 2006-334639 A

  As shown in the conventional friction stir welding method described above, whether or not the joint formed by friction stir welding is possible depends on the operating conditions of the friction stir welding system, and in particular, is in direct contact with the object to be welded. It depends greatly on the movement of the rotating tool. Therefore, in order to accurately determine whether or not the joining state is possible, it is conceivable to constantly monitor a plurality of physical quantities such as a load, strain amount, and vibration applied to the rotating tool during operation. However, when a plurality of physical quantities are constantly monitored, there are problems that the number of sensors increases and the analysis routine becomes complicated.

  The present invention has been made to solve the above-described problems, and provides a friction stir welding system and a friction stir welding method capable of accurately determining whether or not a joining state is possible while reducing a processing burden. Objective.

  In order to solve the above-described problems, the inventors of the present application focused on the amount of energy fluctuation consumed in the friction stir welding system during joining in the process of earnest research. As a result, the amount of energy consumed in the friction stir welding system depends on the load on the system and is sharp when the friction stir welding starts, i.e. when the rotating tool is pushed into the abutting part of the metal material. It was found that a constant peak was generated and maintained at a substantially constant level during friction stir welding. In addition, a slight peak occurs when the friction stir welding is completed and the rotating tool is pulled up from the abutting part, and after that, after a sudden drop and a slight dip, the level returns to the level before the start of the friction stir welding. I understood.

  Therefore, the inventor of the present application can process a plurality of physical quantities over the entire period of friction stir welding by determining whether or not there is an abnormality in a portion where the fluctuation of energy amount is remarkable in the period from the start to completion of friction stir welding. The present invention has been conceived by obtaining the knowledge that it is possible to accurately determine whether or not a joined state is possible.

  A friction stir welding system according to the present invention is a friction stir welding system that forms a joint along a contact portion by rotating a rotary tool that is pushed into the contact portion between the end faces of a metal material. From the start to the end of stir welding, the physical quantity detection means for detecting a change in physical quantity related to the amount of energy supplied to the system, and the rotating tool is in contact with the measurement output signal obtained from the physical quantity detection means. Output signal extraction means for extracting a first part corresponding to when pushed in and a second part corresponding to when the rotary tool is pulled up from the contact part, respectively, and extracted by the output signal extraction means Based on a comparison between the first part and the second part and a preset threshold value, an abnormality determination stage for determining whether there is an abnormality in the output signal for measurement, and an abnormality determination unit Based on that determination result, it is characterized by comprising a bonding state determining means for determining whether the bonding state of the bonding portion.

  In this friction stir welding system, a change in physical quantity related to the amount of energy supplied to the system is detected by the physical quantity detection means from the start to the completion of friction stir welding. Of the output signals for measurement acquired from the physical quantity detection means, the first portion corresponding to when the rotary tool is pushed into the contact portion, and the case where the rotary tool is pulled up from the contact portion. The second portion is compared with a preset threshold value, and based on this, the presence / absence of abnormality in the output signal for measurement is determined. As described above, in this friction stir welding system, a single physical quantity is monitored, and in the period from the start to the completion of friction stir welding, the portion where the fluctuation of the energy amount is remarkable is extracted to determine whether there is an abnormality. Therefore, it is possible to accurately determine whether or not the joined state is possible while reducing the processing load.

  In addition, the first calculation means for calculating the upper management limit value and the lower management limit value of the first portion extracted from the reference output signal acquired in advance, and the first part extracted from the reference output signal acquired in advance. And a second calculating means for calculating a normalized value obtained by multiplying the standard deviation of the difference signal obtained by subtracting the moving average from the portion of 2, and the abnormality determining means includes an output for measurement. A first abnormality determining means for determining whether there is an abnormality in the first part based on whether or not the first part of the signal is between the upper control limit and the lower control limit; and an output signal for measurement Second abnormality determining means for determining whether or not there is an abnormality in the second part based on whether or not a difference signal obtained by subtracting the moving average from the second part in FIG. It is preferable.

  The upper control limit value and the lower control limit value are obtained by calculating a standard deviation for the first part of the reference output signal and multiplying the standard deviation by an integer to obtain a normalized value of the reference output signal. It is a value obtained by adding and subtracting to the first part. Since these threshold values are set with a certain numerical value width along the waveform of the first portion of the reference output signal, the measurement shows a steep rise when the rotary tool is pushed into the contact portion. It is possible to easily determine whether there is an abnormality in the first portion of the output signal for use. On the other hand, regarding the second portion of the output signal for measurement, the presence / absence of abnormality is determined using a difference signal obtained by subtracting the moving average. As a result, it is possible to easily determine the presence or absence of an abnormality in the second portion by capturing a slight peak and dip generated in the second portion of the output signal for measurement when the rotary tool is pulled up from the contact portion. it can.

  Further, the friction stir welding method according to the present invention is a friction stir welding method for forming a joint portion along a contact portion by rotating a rotary tool pushed into the contact portion between the end faces of the metal material. From the start to the completion of friction stir welding, the physical quantity detection step for detecting the change in the physical quantity related to the amount of energy supplied to the system by the physical quantity detection means, and the rotation of the output signal for measurement acquired from the physical quantity detection means An output signal extraction step for extracting a first portion corresponding to when the tool is pushed into the contact portion and a second portion corresponding to when the rotary tool is pulled up from the contact portion; An abnormality determination step for determining whether there is an abnormality in the output signal for measurement, based on a comparison between the first and second portions and a preset threshold value, and an abnormality determination step Based on the determination result, it is characterized by comprising a bonding state determination step of determining whether the bonding state of the bonding portion.

  In this friction stir method, a change in physical quantity related to the amount of energy supplied to the system is detected by the physical quantity detection means from the start to the completion of friction stir welding. Of the output signals for measurement acquired from the physical quantity detection means, the first portion corresponding to when the rotary tool is pushed into the contact portion, and the case where the rotary tool is pulled up from the contact portion. The second portion is compared with a preset threshold value, and based on this, the presence / absence of an abnormality in the output signal for the side picture is determined. As described above, in this friction stir welding system, a single physical quantity is monitored, and in the period from the start to the completion of friction stir welding, the portion where the fluctuation of the energy amount is remarkable is extracted to determine whether there is an abnormality. Therefore, it is possible to accurately determine whether or not the joined state is possible while reducing the processing load.

  In addition, a first calculation step of calculating the upper management limit value and the lower management limit value of the first portion extracted from the reference output signal acquired in advance, and the first part extracted from the reference output signal acquired in advance. And a second calculation step of calculating a normalized value obtained by multiplying the standard deviation of the difference signal obtained by subtracting the moving average from the portion of 2, and the abnormality determination step includes an output for measurement A first abnormality determining step for determining whether there is an abnormality in the first part based on whether or not the first part of the signal is between the upper control limit and the lower control limit; and an output signal for measurement A second abnormality determination step for determining whether or not there is an abnormality in the second part based on whether or not a difference signal obtained by subtracting the moving average from the second part in FIG. It is preferable.

  Accordingly, it is possible to easily determine whether there is an abnormality in the first portion of the measurement output signal that shows a steep rise when the rotary tool is pushed into the contact portion. Further, it is possible to easily determine the presence or absence of an abnormality in the second portion by capturing a slight peak and dip generated in the second portion of the output signal for measurement when the rotary tool is pulled up from the contact portion. .

  According to the friction stir welding system and the friction stir welding method according to the present invention, it is possible to accurately determine whether or not the joining state is possible while reducing the processing load.

  Hereinafter, preferred embodiments of a friction stir welding system and a friction stir welding method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a view showing a state of friction stir welding of metal materials according to an embodiment of a friction stir welding system according to the present invention. As shown in FIG. 1, the friction stir welding system 1 includes a rotating tool 3 disposed above metal materials 2 a and 2 b to be joined. The rotating tool 3 is a metal material having a substantially cylindrical shape, and a substantially cylindrical probe 4 having a diameter smaller than the diameter of the body portion of the rotating tool 3 is provided at the center of the tip of the rotating tool 3.

  In performing the friction stir welding, the friction stir welding system 1 first rotates the rotary tool 3 at a predetermined rotation speed. Then, the rotating tool 3 is lowered toward the metal materials 2a and 2b, and the rotating tool 3 is brought into contact with the butted portion (abutting portion) L between the end faces of the metal materials 2a and 2b. Push into one end of L.

  Next, the friction stir welding system 1 moves the rotary tool 3 along the butted portion L as shown in FIG. As a result, frictional heat is generated between the probe 4 of the rotary tool 3 and the metal materials 2a and 2b, and joints W are sequentially formed at the butt portion L by plastic flow due to the frictional heat. After the rotary tool 3 reaches the other end side of the abutting portion L, the rotating tool 3 is raised and the probe 4 is pulled up from the abutting portion L as shown in FIG. Thereafter, the rotation of the rotary tool 3 is stopped, and the process ends.

  As shown in FIG. 4, such a friction stir welding system 1 includes, as functional components, a system power source 101, a drive motor 102, a feeding device 103, a power detection sensor (physical quantity detection means) 104, Output signal extraction unit (output signal extraction unit) 105, output signal determination unit (first abnormality determination unit, second abnormality determination unit, first calculation unit, second calculation unit) 106, and bonding state determination unit (bonding state) Determination means) 107, determination result storage unit 108, and stop control unit 109.

  The system power supply 101 is a part that distributes the power supplied from the external power supply 201 to the drive motor 102, the feeding device 103, and the like. The drive motor 102 is a part that applies a rotational force around the axis to the rotary tool 3. The drive motor 102 is connected to the rotary tool 3 by connection means (not shown), and rotates the rotary tool 3 at a rotational speed of 600 rpm, for example.

  The feeding device 103 is a device that controls the movement of the rotary tool 3. The feeding device 103 lowers the rotary tool 3 with respect to the metal materials 2a and 2b when starting the friction stir welding. The feeding device 103 moves the rotary tool 3 along the abutting portion L of the metal materials 2a and 2b, and then raises the rotary tool 3 relative to the metal materials 2a and 2b. The moving speed of the rotary tool 3 relative to the abutting portion L is set to, for example, 600 mm / min.

  The power detection sensor 104 is a part that detects the effective power supplied from the external power source 201 to the system power source 101 from when the system power source is turned on until friction stir welding is started and completed. The power detection sensor 104 sequentially outputs an output signal corresponding to the detected active power to the output signal extraction unit 105.

  FIG. 5 is a diagram illustrating an example of a waveform pattern of an output signal for measurement from the power detection sensor 104. The effective power detected by the power detection sensor 104 increases or decreases in proportion to the load applied to the friction stir welding system 1 and is used as an index indicating whether or not the friction stir welding is performed in a normal state. In the example shown in FIG. 5, the output signal S for measurement rises to a certain level when the system power supply 101 is turned on at time t0 and the rotation of the rotary tool 3 by the drive motor 102 starts (S1 portion).

  Next, the output signal S for measurement rises sharply when the probe 4 of the rotating rotary tool 3 is pushed into one end of the butt portion L of the metal materials 2a and 2b at time t1 (S2 portion), and then While the rotary tool 3 moves along the abutting portion L from the time t2 to the time t3, it is maintained substantially constant at a higher level than the S1 portion (S3 portion). When the rotary tool 3 reaches the other end of the abutting portion L at time t3 and the rotary tool 3 is pulled up from the metal materials 2a and 2b, a slight peak occurs in the output signal S for measurement, and then suddenly drops. After a slight dip occurs, the original level is restored (S4 portion). After that, when the system power supply 101 is turned off, it becomes almost 0 level (S5 portion).

  The output signal extraction unit 105 includes an S2 portion (first portion) corresponding to the waveform pattern of the measurement output signal S acquired from the power detection sensor 104 when the rotary tool 3 is pushed into the matching portion L. The S4 portion (second portion) corresponding to when the rotary tool is pulled up from the butt portion L is extracted. The output signal extraction unit 105 outputs the extracted waveform pattern to the output signal determination unit 106.

  The output signal determination unit 106 is a part that monitors the waveform of the output signal output from the output signal extraction unit 105 and determines whether there is an abnormality. More specifically, the output signal determination unit 106 first performs waveform analysis using the control limit for the S2 portion of the output signal S for measurement. In this waveform analysis, friction stir welding is performed in advance on a reference metal material (not shown). Then, the waveform pattern of the reference output signal output from the power detection sensor 104 is acquired, and the S2 portion and the S4 portion of the waveform pattern of the reference output signal are extracted.

  Next, a moving average of the output values of the S2 portion in the waveform pattern of the reference output signal is obtained, and each output value included in the waveform pattern after the moving average is normalized based on the standard deviation σ. Then, as shown in FIG. 6, the normalized value obtained by multiplying the standard deviation σ by 3 is added to the moving average value (+ 3σ) as the upper control limit, and the normalized value is subtracted from the moving average value. Let (−3σ) be the lower control limit. Between the upper management limit waveform pattern A1 and the lower management limit waveform pattern A2, an allowable area is set with a predetermined numerical width.

  As shown in FIG. 7A, in the output signal determination unit 106, the S2 portion of the measurement output signal S falls between the upper control limit waveform pattern A1 and the lower control limit waveform pattern A2. In this case, it is determined that there is no abnormality in the S2 portion. Further, as shown in FIG. 7B, the output signal determination unit 106 has the S2 portion of the measurement output signal S within the upper control limit waveform pattern A1 and the lower control limit waveform pattern A2. If not, it is determined that there is an abnormality in the S2 portion.

  The output signal determination unit 106 generates determination result information indicating the determination result, and outputs the determination result information to the bonding state determination unit 107. When the output signal determination unit 106 generates determination result information indicating that there is an abnormality in the S2 portion, the output signal determination unit 106 also outputs the determination result information to the stop control unit 109.

  Next, the output signal determination unit 106 performs waveform analysis using the difference signal on the S4 portion of the measurement output signal S. An example of this waveform analysis is shown in FIG. FIG. 8A is an enlarged view showing the waveform pattern of the S4 portion of the output signal S for measurement. As shown in FIG. 8B, the output signal determination unit 106 obtains a moving average of the output values of the acquired waveform pattern of the S4 portion.

  Next, the output signal determination unit 106 outputs the output included in the waveform pattern P1 after the moving average illustrated in FIG. 8B from the output value included in the waveform pattern of the S4 portion illustrated in FIG. Subtract the value. As a result, as shown in FIG. 8C, a waveform pattern P2 of the differential signal centered on the 0 level is obtained. As a threshold for determining whether or not the waveform pattern P2 of the difference signal is abnormal, for example, the standard deviation σ of the difference signal obtained by subtracting the moving average from the output value included in the S4 portion of the reference output signal is tripled The normalized value ± 3σ obtained in this way is used.

  When the output value included in the waveform pattern P2 of the difference signal is within the threshold ± 3σ, the output signal determination unit 106 determines that there is no abnormality in the S4 portion of the measurement output signal S. In addition, the output signal determination unit 106 determines that there is an abnormality in the S4 portion of the measurement output signal S when there is any value exceeding the threshold value ± 3σ among the output values included in the waveform pattern P2 of the difference signal. Judge that there is. The output signal determination unit 106 generates determination result information indicating the determination result, and outputs the determination result information to the bonding state determination unit 107.

  The joining state determination unit 107 is a part that determines whether or not the joining state of the joining part W in the metal materials 2a and 2b is possible based on the determination result by the output signal determination unit 106. The joint state determination unit 107 determines that the joint state of the joint portion W is acceptable when receiving a determination result indicating that there is no abnormality in both the S2 portion and the S4 portion of the output signal S for measurement. The result information is output to the determination result storage unit 108. On the other hand, when the joint state determination unit 107 receives a determination result indicating that there is an abnormality in at least one of the S2 part and the S4 part of the measurement output signal S, the joint state of the joint part W is not possible. The determination result information is output to the determination result storage unit 108.

  The determination result storage unit 108 is a part that stores a determination result regarding the bonding state of the bonding portion W. FIG. 9 is a diagram illustrating an example of information stored in the determination result storage unit 108. In the example shown in FIG. 9, the product No. of the joined body of the metal materials 2a and 2b. In association with “00001”, “00002”, etc., determination result information “OK” and “NG” of the joining state are stored.

  The stop control unit 109 is a part that performs control related to an emergency stop of the friction stir welding system 1. The stop control unit 109 immediately stops the feeding device 103 and the drive motor 102 when the determination result information indicating that the S2 portion of the measurement output signal S is abnormal is received from the output signal determination unit 106.

  Subsequently, the operation of the friction stir welding system 1 will be described. FIG. 10 is a flowchart showing the operation of the friction stir welding system 1.

  As shown in FIG. 10, when the system power supply 101 of the friction stir welding system 1 is turned on and a predetermined operation is performed by the user, the rotation of the rotary tool 3 by the drive motor 102 is started (step S01). Next, the rotary tool 3 is lowered toward the metal materials 2a and 2b, and the probe 4 of the rotary tool 3 is pushed into one end side of the butted portion L of the metal materials 2a and 2b (step S02).

  When the rotary tool 3 is pushed in, it is determined whether there is an abnormality in the S2 portion of the measurement output signal S from the power detection sensor 104 (step S03). In step S03, when it is determined that there is an abnormality in the S2 portion of the measurement output signal, the feeder 103 and the drive motor 102 are immediately stopped (step S09). When it is determined that there is no abnormality in the S2 portion of the measurement output signal S, the rotating device 3 is moved along the abutting portion L of the metal materials 2a and 2b by the feeding device 103 (step S04). Thereby, the joining part W is formed in the butt | matching part L one by one.

  After the rotary tool 3 reaches the other end side of the abutting portion L, the rotating tool 3 is raised, and the probe 4 of the rotating tool 3 is pulled up from the other end side of the abutting portion L (step S05). When the rotary tool 3 is pulled up, it is determined whether there is an abnormality in the S4 portion of the output signal from the power detection sensor 104 (step S06).

  After step S06, it is determined whether or not the bonded state of the bonded portions W of the metal materials 2a and 2b is possible from the determination result of the presence or absence of abnormality in the S2 portion and the S4 portion of the measurement output signal S (step S07). As a result of the determination, the product number of the joined body of the metal materials 2a and 2b. Are stored in association with each other (step S08).

  As described above, in the friction stir welding system 1, the power detection sensor 104 detects a change in the effective power supplied to the system from the start to the completion of the friction stir welding. Of the output signal S for measurement acquired from the power detection sensor 104, the S2 portion corresponding to when the rotary tool 3 is pushed into the butted portion L and the rotary tool 3 is pulled up from the butted portion L. The corresponding S4 portion is compared with a preset threshold value, and based on this, the presence or absence of an abnormality in the measurement output signal S is determined. As described above, in the friction stir welding system 1, the active power that is a single physical quantity is monitored, and the portion of the period from the start to the completion of the friction stir welding has a significant fluctuation in the effective power supplied to the system. Therefore, it is possible to accurately determine whether or not the joint portion W is in a joined state while reducing the processing load.

  Further, in the friction stir welding system 1, for the abnormality determination of the S2 portion of the measurement output signal S, the upper management limit value and the lower management limit value calculated from the reference output signal are used as predetermined threshold values, and the S4 portion For the abnormality determination, a normalized value (± 3σ) obtained by multiplying the standard deviation σ of the output value included in the S4 portion of the reference output signal by an integer is used as a predetermined threshold value.

  Since the upper control limit value and the lower control limit value are set with a certain numerical width along the waveform of the reference output signal, the abnormality in the S2 portion of the measurement output signal S having a steep waveform The presence or absence of can be easily determined. Also, the moving average difference process is equivalent to the function of a bandpass filter, and only a specific frequency related to the presence or absence of abnormality can be extracted from various frequencies included in the S4 portion of the measurement output signal S. . Thereby, when the rotary tool is pulled up from the abutting portion, a slight peak and dip generated in the second portion of the output signal for measurement are accurately captured, and it is easily determined whether there is an abnormality in the second portion. Can do.

  In the friction stir welding system 1, when the output signal determination unit 106 determines that there is an abnormality in the S2 portion of the measurement output signal S, the stop control unit 109 immediately stops the feeding device 103 and the drive motor 102. It is supposed to be. When an abnormality of the friction stir welding system 1 is recognized when the rotary tool 3 is pushed into the butted portion L of the metal material 2a, 2b, the cause of the abnormality can be easily grasped by interrupting the friction stir welding on the spot. Become. In addition, secondary abnormalities that can occur by continuing the friction stir welding in a state where there is an abnormality, such as the shaft breakage of the feeding device 103 or the drive motor 102, can be prevented.

  Furthermore, in the friction stir welding system 1, the judgment result of the joining state of the joint W is obtained from the product No. It is stored in association with. Thereby, it becomes possible to establish the traceability (traceability) of the product using the metal materials 2a and 2b.

  The present invention is not limited to the above embodiment. In the above-described embodiment, the friction agitation between the ends of the flat plate is exemplified, but the present invention is also applicable to various types of joints such as a flare joint and a T joint.

It is the figure which showed the process of the friction stir welding of the metal material by the friction stir welding system which concerns on one Embodiment of this invention. FIG. 2 is a diagram showing a step subsequent to FIG. 1. FIG. 3 is a diagram showing a subsequent process of FIG. 2. It is the figure which showed the functional component of the friction stir welding system which concerns on one Embodiment of this invention. It is the figure which showed an example of the waveform pattern of the output signal for a measurement from an electric power detection sensor. It is the figure which showed an example of the waveform pattern of the upper management limit and lower management limit calculated from S2 part of the waveform pattern of the output signal for reference | standard. It is the figure which showed an example of judgment of the presence or absence of abnormality in the output signal S2 part for a measurement. It is the figure which showed an example of judgment of the presence or absence of abnormality in the output signal S4 part for measurement. It is the figure which showed an example of the information stored in a judgment result storage part. It is the flowchart which showed operation | movement of the friction stir welding system shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Friction stir welding system, 2a, 2b ... Metal material, 3 ... Rotating tool, 104 ... Electric power detection sensor (physical quantity detection means), 105 ... Output signal extraction part (output signal extraction means), 106 ... Output signal judgment part ( 1st abnormality judgment means, 2nd abnormality judgment means, 1st calculation means, 2nd calculation means) 107 ... Joining state judgment part (joining state judgment means), L ... Butt part, S ... Output signal for measurement, W ... joint.

Claims (4)

A friction stir welding system that forms a joint along the abutting portion by rotating a rotating tool pushed into the abutting portion between the end faces of the metal material,
Rotating means for rotating the rotating tool;
Moving means for moving the rotating tool;
Physical quantity detection means for detecting a change in physical quantity related to the amount of energy supplied to the rotating means and the moving means between the start and completion of friction stir welding;
Of the output signal for measurement obtained from the physical quantity detecting means, a first portion corresponding to when said rotating tool is pushed into the abutment portion by said moving means, said rotating tool by the moving means and the An output signal extracting means for extracting each of the second portions corresponding to the second portion when it is lifted from the contact portion;
Based on the comparison of the output signal extracted by the extracting means and the first and second portions with a predetermined threshold value, the abnormality determination means to determine the presence or absence of abnormality of the output signal for the measurement When,
A friction stir welding system comprising: a joining state judging unit that judges whether or not the joining state of the joining part is possible based on a judgment result by the abnormality judging unit. First calculating means for calculating an upper management limit value and a lower management limit value of the first portion extracted from a reference output signal acquired in advance;
Second calculating means for calculating a normalized value obtained by multiplying the standard deviation of the difference signal obtained by subtracting the moving average from the second portion extracted from the reference output signal acquired in advance, by an integer multiple; Further comprising
The abnormality determining means is
A first abnormality for determining whether or not there is an abnormality in the first part based on whether the first part in the output signal for measurement falls between the upper management limit and the lower management limit Judgment means,
Based on whether or not a difference signal obtained by subtracting the moving average from the second part of the output signal for measurement exceeds the normalized value, it is determined whether there is an abnormality in the second part. The friction stir welding system according to claim 1, further comprising second abnormality determination means. A friction stir welding method for forming a joint along the abutting part by rotating a rotating tool pushed into the abutting part between the end faces of the metal material,
A physical quantity detection step for detecting, by a physical quantity detection means, a change in a physical quantity related to the amount of energy supplied to a rotating means for rotating the rotary tool and a moving means for moving the rotary tool from the start to completion of friction stir welding; ,
Of the output signal for measurement obtained from the physical quantity detecting means, a first portion corresponding to when said rotating tool is pushed into the abutment portion by said moving means, said rotating tool by the moving means and the An output signal extraction step for extracting a second part corresponding to the second part when the part is pulled up from the contact part;
An abnormality determination step of determining whether there is an abnormality in the output signal for measurement based on a comparison between the first part and the second part and a preset threshold;
A friction stir welding method comprising: a joining state judgment step for judging whether or not the joining state of the joining portion is possible based on a judgment result in the abnormality judgment step. A first calculation step of calculating an upper management limit value and a lower management limit value of the first portion extracted from a reference output signal acquired in advance;
A second calculation step of calculating a normalized value obtained by multiplying the standard deviation of the difference signal obtained by subtracting the moving average from the second portion extracted from the reference output signal acquired in advance, as an integer; Further comprising
The abnormality determination step includes:
A first abnormality for determining whether or not there is an abnormality in the first part based on whether the first part in the output signal for measurement falls between the upper management limit and the lower management limit A decision step;
Based on whether or not a difference signal obtained by subtracting the moving average from the second part of the output signal for measurement exceeds the normalized value, it is determined whether there is an abnormality in the second part. The friction stir welding method according to claim 3, further comprising a second abnormality determination step.

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