JP2009082951A - Friction welding system and friction welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction welding system and a friction welding method which can determine whether a welding state is good or not with high precision, with a simple constitution. <P>SOLUTION: The friction welding system 1 monitors the pre-stage part S1 and rising part S2 of an output signal S from an electric power detection sensor 104 using an upper control limit value and a lower control limit value. Since the upper control limit value and the lower control limit value are set with a fixed numerical value width along the waveform of an output signal for standards, the presence of the abnormality in the pre-stage part S1 and the rising part S2 which forms a steep waveform can be easily determined. On the other hand, the succeeding part S3 of the output signal S performs monitoring using a differential signal obtained by differentiating moving average. Thus, the presence of the abnormality of the flat succeeding part S3 can be easily determined. Upon such monitoring, since the friction welding system 1 applies only effective electric power fed from an external power source 201 to a system power source 101, the complication of the constitution can be evaded as well. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a friction joining system and a friction joining method.

As methods for joining metal materials, friction joining methods such as friction stir welding, friction pressure welding, and friction sliding joining are known. In the friction welding method, various control techniques for determining whether or not a joining state is possible have been developed. For example, in the friction welding method described in Patent Document 1, the amount of change per unit time of pressure during pressure welding is monitored, and the pressure every time pressure welding is performed is controlled based on this amount of change.
JP 2006-255748 A

  In order to accurately determine whether or not the joining state is possible, it is conceivable to monitor a plurality of physical quantities such as a tool load, a processing point temperature, an atmospheric temperature, a strain amount, and vibration in addition to the above-described load at the time of pressure welding. However, when the physical quantity to be monitored increases, 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 problems, and an object of the present invention is to provide a friction joining system and a friction joining method capable of accurately determining whether or not a joining state is possible with a simple configuration.

  In order to solve the above problems, the inventors of the present application focused on the amount of fluctuation of energy consumed in the friction welding system when joining in the process of earnest research. As a result, the amount of energy consumed in the friction welding system depends on the load applied to the system, and at the start of friction welding, that is, when the friction member driven by the driving means contacts the metal material to be joined. It has been found that it rises sharply and then remains at a substantially constant level until the friction welding is completed.

  Therefore, the inventor of the present application considers the shape of the waveform described above, and analyzes the initial waveform of the physical quantity related to the energy amount and the waveform until the friction welding is completed by using different methods. The present invention has been conceived with the knowledge that it is possible to accurately determine whether or not a joined state is possible.

  A friction welding system according to the present invention is a friction welding system including a driving unit that drives a friction member so that friction heat is generated in a joint portion of a metal material to be joined, from the start to the completion of friction welding. Between the physical quantity detection means for detecting the change in the physical quantity related to the amount of energy supplied to the system and the output signal from the physical quantity detection means, the rising part when the friction member driven by the drive means contacts the joint, First determination means for determining whether there is an abnormality in the rising portion based on whether the rising portion of the rising portion of the reference output signal set in advance is within the upper management limit value and the lower management limit value; Of the output signals from the detection means, calculate the moving average for the subsequent part until the driving of the friction member stops, and subtract the moving average from the output signal of the subsequent part. Second judgment means for judging the presence or absence of an abnormality in the subsequent part based on a comparison between the difference signal and a preset threshold value, and based on the judgment results by the first judgment means and the second judgment means, It is characterized by comprising availability judging means for judging whether or not the joining state is possible.

  In this friction welding system, the rising portion of the output signal from the physical quantity detection means is monitored using the upper management limit value and the lower management limit value. The upper control limit value and the lower control limit value are obtained by calculating the standard deviation of the output value of the reference output signal, and then outputting the normalized value obtained by multiplying the standard deviation by an integer to the output of the reference output signal. It is a value obtained by adding and subtracting to a value. Therefore, the upper control limit value and the lower control limit value are set with a certain numerical range along the waveform of the rising portion of the output signal for reference, and it is easy to check whether there is an abnormality in the steep rising portion. Can be judged. On the other hand, in this friction welding system, the subsequent portion of the output signal from the physical quantity detection means is monitored using a difference signal obtained by subtracting the moving average. Thereby, it is possible to easily determine whether there is an abnormality in the flat subsequent portion. In monitoring, only a single physical quantity related to the amount of energy supplied to the system is handled, and the complexity of the configuration is also avoided.

  In addition, it is preferable to further include a stopping unit that stops the driving unit when the first determining unit determines that there is an abnormality in the rising portion. If a system abnormality is recognized at the start of friction welding, it is easy to grasp the cause of the abnormality by interrupting the friction welding on the spot. In addition, secondary abnormalities can be prevented from occurring.

  Further, of the output signals from the physical quantity detection means, the preceding stage from when the friction member is driven by the driving means until the friction member comes into contact with the joint is superposed on the preceding part of the preset reference output signal. It is preferable to further include third determination means for determining the presence or absence of an abnormality in the previous stage based on whether or not the value is within the limit value and the lower control limit value. If it carries out like this, it will become possible to judge the joining state of a junction part still more accurately.

  In addition, it is preferable to further include a stopping unit that stops the driving unit when the third determining unit determines that there is an abnormality in the preceding stage portion. If an abnormality in the system is recognized before the start of friction welding, it is easier to grasp the cause of the abnormality by interrupting the friction welding on the spot. In addition, secondary abnormalities can be prevented from occurring.

  The friction joining method according to the present invention is a friction joining method including a step of driving a friction member by a driving means so that friction heat is generated in a joint portion of metal materials to be joined. A physical quantity detection step for detecting a change in physical quantity related to the amount of energy supplied to the system from the start to the completion by the physical quantity detection means, and among the output signals from the physical quantity detection means, the friction member driven by the drive means is a metal material. Whether or not there is an abnormality in the rising part is determined based on whether the rising part when touching is within the upper control limit value and the lower control limit value of the preset output signal for the reference. The moving average is calculated for the first determination step to be determined and the subsequent portion of the output signal from the physical quantity detection means until the driving of the friction member stops. A second determination step for determining whether there is an abnormality in the subsequent portion based on a comparison between a difference signal obtained by subtracting the moving average from the output signal of the subsequent portion and a preset threshold value; and a first determination step And a determination step for determining whether or not the bonded state of the bonded portion is possible based on the determination result of the second determination step.

  In this friction welding method, the rising portion of the output signal from the physical quantity detection means is monitored using the upper management limit value and the lower management limit value. The upper control limit value and the lower control limit value are obtained by calculating the standard deviation of the output value of the reference output signal, and then outputting the normalized value obtained by multiplying the standard deviation by an integer to the output of the reference output signal. It is a value obtained by adding and subtracting to a value. Therefore, the upper control limit value and the lower control limit value are set with a certain numerical range along the waveform of the rising portion of the output signal for reference, and it is easy to check whether there is an abnormality in the steep rising portion. Can be judged. On the other hand, in this friction welding method, the subsequent portion of the output signal from the physical quantity detection means is monitored using a difference signal obtained by subtracting the moving average. Thereby, it is possible to easily determine whether there is an abnormality in the flat subsequent portion. In monitoring, only a single physical quantity related to the amount of energy supplied to the system is handled, and the complexity of the configuration is also avoided.

  Moreover, it is preferable to further include a stop step for stopping the driving means when it is determined in the first determination step that there is an abnormality in the rising portion. If a system abnormality is recognized at the start of friction welding, it is easy to grasp the cause of the abnormality by interrupting the friction welding on the spot. In addition, secondary abnormalities can be prevented from occurring.

  Further, of the output signals from the physical quantity detection means, the preceding stage from when the friction member is driven by the driving means until the friction member comes into contact with the joint is superposed on the preceding part of the preset reference output signal. It is preferable to further include a third determination step for determining whether or not there is an abnormality in the preceding stage based on whether or not the value is within the limit value and the lower control limit value. If it carries out like this, it will become possible to judge the joining state of a junction part still more accurately.

  In addition, it is preferable to further include a stopping unit that stops the driving unit when it is determined in the third determining step that there is an abnormality in the preceding stage portion. If an abnormality in the system is recognized before the start of friction welding, it is easier to grasp the cause of the abnormality by interrupting the friction welding on the spot. In addition, secondary abnormalities can be prevented from occurring.

  According to the friction joining system and the friction joining method according to the present invention, it is possible to accurately determine whether or not the joining state is possible with a simple configuration.

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

  FIG. 1 is a diagram showing an outline of friction welding of a metal material by a friction welding system according to an embodiment of the present invention. As shown in FIG. 1, the friction joining system 1 is configured as a system that joins end surfaces 2 a and 3 a of metal materials 2 and 3, for example. The metal materials 2 and 3 are, for example, carbon steel, chromium-molybdenum steel, stainless steel, and aluminum alloy, and have a rod shape with a diameter of about 50 to 200 mm and a length of about 500 mm to 1500.

  In joining, the friction welding system 1 first rotates one metal material 2 around an axis as shown in FIG. Next, as shown in FIG. 1 (b), the end surface 2a of the rotating metal material 2 is brought into contact with the end surface 3a of the other metal material 3, and the end surfaces 2a and 3a of the metal materials 2 and 3 are heated and melted by frictional heat. To do. After the end faces 2a and 3a are sufficiently melted, as shown in FIG. 1C, the metal materials 2 and 3 are subjected to upset pressure to form the joint portion W. The friction welding system 1 determines whether or not the formed bonded portion W is in a bonded state, and stores the determination result for each of the metal materials 2 and 3.

  As shown in FIG. 2, such a friction welding system 1 includes, as functional components, a system power supply 101, a drive motor (drive means) 102, a feeding device 103, and a power detection sensor (physical quantity detection means). 104, an output signal determination unit (first determination unit to third determination unit) 105, a joining state determination unit (allowability determination unit) 106, a determination result storage unit 107, and a stop control unit (stop unit) 108. I have.

  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 connected to one metal material 2 by connection means (not shown) and applies a rotational force around the axis to the metal material 2. The drive motor 102 causes the metal material 2 itself to be connected to function as a friction member by rotating the metal material 2 at a weekly speed of 6.0 to 9.0 m / s, for example.

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

FIG. 3 is a diagram illustrating an example of a waveform pattern of an output signal from the power detection sensor 104. The active power detected by the power detection sensor 104 increases or decreases in proportion to the load applied to the friction welding system 1 and is used as an index indicating whether or not the friction welding is performed in a normal state. In the example shown in FIG. 3, the output signal S rises to a certain level when the system power supply 101 is turned on at time t ₀ and the rotation of the metal material 2 by the drive motor 102 starts (previous portion S1).

Then, the output signal S is sharply rising in the moment when the end surface 2a of the metal material 2 which rotates at time t ₁ is in contact with the end face 3a of the other metal member 3 (rising portion S2), then, from time t ₂ while the end face 2a of the metal material 2,3, 3a is heated and melted over the t _3, it is maintained substantially constant at a higher level than the preceding stage portion S1 (trailing portion S3). Friction joint is completed at time t _3, when the rotation of the metal material 2 by the driving motor 102 is stopped, the output signal S is decreased to almost the same level as preliminary portion S1, substantially the system power supply 101 is turned off 0 It becomes a level (residual portion S4).

  The output signal determination unit 105 is a part that monitors the waveform of the output signal sequentially output from the power detection sensor 104 and determines whether there is an abnormality. More specifically, the output signal determination unit 105 first performs waveform analysis using the control limit for the previous stage portion S1 of the output signal S. In this waveform analysis, a reference metal material (not shown) is friction-bonded in advance, and a waveform pattern of a reference output signal output from the power detection sensor 104 at that time is acquired.

  Next, a moving average of the output values of the preceding stage 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. 4, 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. As a result, an allowable area is set with a predetermined numerical value width between the upper management limit waveform pattern A1 and the lower management limit waveform pattern A2.

  As shown in FIG. 5 (a), the output signal determination unit 105 determines that the preceding part S1 of the output signal S is between the upper control limit waveform pattern A1 and the lower control limit waveform pattern A2. Determines that there is no abnormality in the front part S1. Further, as shown in FIG. 5B, the output signal determination unit 105 does not have the preceding part S1 of the output signal S 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 an abnormality in the front part S1.

  The output signal determination unit 105 generates determination result information indicating the determination result and outputs the determination result information to the bonding state determination unit 106. When the output signal determination unit 105 determines that there is an abnormality in the preceding portion S1, the output signal determination unit 105 also outputs the determination result information to the stop control unit 108.

  Next, the output signal determination unit 105 performs waveform analysis using the control limit on the rising portion S2 of the output signal S, as in the case of the preceding portion S1. As shown in FIG. 6, the output signal determination unit 105 is preset with an upper management limit waveform pattern B1 and a lower management limit waveform pattern B2 calculated from the rising portion of the waveform pattern of the reference output signal. ing.

  As shown in FIG. 7A, the output signal determination unit 105 determines that the rising portion S2 of the output signal S is between the upper control limit waveform pattern B1 and the lower control limit waveform pattern B2. Determines that there is no abnormality in the front part S1. Further, as shown in FIG. 7B, the output signal determination unit 105 does not include the rising portion S2 of the output signal S between the upper control limit waveform pattern B1 and the lower control limit waveform pattern B2. In this case, it is determined that there is an abnormality in the rising portion S2.

  The output signal determination unit 105 generates determination result information indicating the determination result and outputs the determination result information to the bonding state determination unit 106. When the output signal determination unit 105 determines that there is an abnormality in the rising portion S2, the output signal determination unit 105 also outputs the determination result information to the stop control unit 108.

  Further, the output signal determination unit 105 performs waveform analysis using a predetermined threshold for the subsequent portion S3 of the 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 subsequent portion S3. As shown in FIG. 8B, the output signal determination unit 105 obtains a moving average of the output values of the acquired waveform pattern of the subsequent portion S3.

  Next, the output signal determination unit 105 is included in the waveform pattern P1 after the moving average shown in FIG. 8B from the output value included in the waveform pattern of the subsequent portion S3 shown in FIG. Subtract the output value. As a result, as shown in FIG. 8C, a waveform pattern P2 of the differential signal centered on the 0 level is obtained. On the other hand, the output signal determination unit 105 obtains a differential signal by the same method for the subsequent portion S3 in the reference output signal described above. Then, the output signal determination unit 105 normalizes the reference difference signal based on the standard deviation σ, and calculates three times the standard deviation σ (± 3σ) as a threshold value.

  When the output value included in the waveform pattern P2 of the differential signal is within the threshold value ± 3σ, the output signal determination unit 105 determines that there is no abnormality in the subsequent portion S3. Further, the output signal determination unit 105 determines that there is an abnormality in the subsequent portion S3 when there is at least one value exceeding the threshold value ± 3σ among the output values included in the waveform pattern P2 of the difference signal. The output signal determination unit 105 generates determination result information indicating the determination result and outputs the determination result information to the bonding state determination unit 106.

  The joining state determination unit 106 is a part that determines whether or not the joining state of the joining parts W in the metal materials 2 and 3 is possible based on the determination result by the output signal determination unit 105. When the joining state determination unit 106 receives a determination result indicating that there is no abnormality in each of the preceding stage S1, the rising part S2, and the subsequent part S3 of the output signal S, the joining state of the joining part W is acceptable. Is output to the determination result storage unit 107. On the other hand, the joint state determination unit 106 determines that there is an abnormality in any one of the preceding part S1, the rising part S2, and the subsequent part S3 of the output signal S. Is output to the determination result storage unit 107.

  The determination result storage unit 107 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 107. In the example shown in FIG. In association with “00001”, “00002”, etc., determination result information “OK” and “NG” of the joining state are stored.

  The stop control unit 108 is a part that performs control related to an emergency stop of the friction welding system 1. The stop control unit 108 immediately stops the feeding device 103 and the drive motor 102 when receiving the determination result information indicating that there is an abnormality in the upstream portion S1 or the rising portion S2 of the output signal S from the output signal determination unit 105.

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

  As shown in FIG. 10, when the system power supply 101 of the friction welding system 1 is turned on and a predetermined operation is performed by the user, the rotation of the metal material 2 by the drive motor 102 is started (step S01). When the rotation of the metal material 2 is started, it is determined whether or not there is an abnormality in the front portion S1 of the output signal S from the power detection sensor 104 (step S02).

  In step S02, when it is determined that there is an abnormality in the front portion S1, the feeding device 103 and the drive motor 102 are immediately stopped (step S11). When it is determined that there is no abnormality in the front portion S1, the metal member 2 is sent to the other metal member 3 side by the feeding device 103, and the end surface 2a of the metal member 2 rotated by the drive motor 102 and the other metal member 3 are rotated. Is brought into contact with the end surface 3a, and friction welding is started (step S03).

  When friction welding is started, it is determined whether there is an abnormality in the rising portion S2 of the output signal S (step S04). If it is determined in step S04 that there is an abnormality in the rising portion S2, the feeding device 103 and the drive motor 102 are immediately stopped as in step S02 (step S11). If it is determined that there is no abnormality in the rising portion S2, the friction welding is continued as it is (step S05).

  After that, when the end faces 2a and 3a of the metal materials 2 and 3 are sufficiently heated and melted, the rotation of the metal material 2 is stopped (step S06). Pressure (see FIG. 1C) is applied (step S07). After the rotation of the metal material 2 is stopped, it is determined whether or not there is an abnormality in the subsequent portion S3 of the output signal S (step S08).

  After step S08, whether or not the joining state of the joint portion W of the metal materials 2 and 3 is determined from the judgment result of the presence or absence of abnormality in the preceding stage S1, the rising part S2, and the succeeding part S3 of the output signal S ( Step S09). As a result of the determination, the product No. And stored in association with each other (step S10).

  As described above, in the friction welding system 1, the front part S1 and the rising part S2 of the output signal S from the power detection sensor 104 are monitored using the upper management limit value and the lower management limit value. Since the upper control limit value and the lower control limit value are set with a certain numerical value width along the waveform of the output signal for reference, the presence or absence of abnormality in the preceding stage portion S1 and the rising portion S2 having steep waveforms Can be easily determined.

  On the other hand, in the friction welding system 1, the subsequent portion S3 of the output signal S from the power detection sensor 104 is monitored using the waveform pattern of the difference signal obtained by subtracting the moving average. The succeeding portion S3 is a portion that normally maintains a substantially constant level, and is a portion that is unlikely to cause a difference in waveform pattern between a normal case and an abnormal case. On the other hand, the moving average difference process is equivalent to the function of the band-pass filter, and it is possible to extract only a specific frequency related to the presence or absence of abnormality from various frequencies included in the subsequent portion S3. Therefore, it is possible to easily determine whether there is an abnormality in the flat subsequent portion S3. In the friction welding system 1, only the effective power supplied from the external power source 201 to the system power source 101 is handled in the above-described monitoring. Therefore, complication of the configuration is also avoided.

  Further, in the friction welding system 1, when the output signal determination unit 105 determines that there is an abnormality in the front stage portion S1 or the rising portion S2 of the output signal S, the stop control unit 108 immediately causes the feeding device 103 and the drive motor 102 to be connected. It comes to stop. When an abnormality of the friction welding system 1 is recognized at the time before the start of the friction welding, or at the time of the start, it is easy to grasp the cause of the abnormality by interrupting the friction welding on the spot. In addition, secondary abnormalities that can occur by continuing the friction welding connection in a state where there is an abnormality, such as a shaft breakage of the feeding device 103 or the drive motor 102, can be prevented.

  Further, in the friction welding system 1, the judgment result of the joining state of the joint W is used as the product No. of the joined body of the metal materials 2 and 3. It is stored in association with. Thereby, it becomes possible to establish the traceability (traceability) of the product using the metal materials 2 and 3.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the effective power is detected as a physical quantity related to the amount of energy supplied to the system, but the current amount may be detected instead of the effective power. In the above embodiment, friction welding is illustrated, but the present invention may be applied to other friction welding such as friction stir welding and friction sliding bonding.

It is the figure which showed the outline | summary of the friction welding of the metal material by the friction welding system which concerns on one Embodiment of this invention. It is the figure which showed the functional component of the friction 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 from an electric power detection sensor. It is the figure which showed an example of the waveform pattern of the upper management limit and the lower management limit calculated from the front | former part of the waveform pattern of the output signal for reference | standard. It is the figure which showed an example of the judgment of the presence or absence of abnormality in the front | former part. It is the figure which showed an example of the waveform pattern of the upper management limit calculated from the rising part of the waveform pattern of the output signal for reference | standard, and the lower management limit. It is the figure which showed an example of the judgment of the presence or absence of abnormality in the rising part. It is the figure which showed an example of the judgment of the presence or absence of abnormality in a subsequent part. It is the figure which showed an example of the information stored in a judgment result storage part. It is the flowchart which showed the operation | movement of the friction welding system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Friction joining system, 2 ... Metal material (friction member), 3 ... Metal material, 102 ... Drive motor (drive means), 104 ... Electric power detection sensor (physical quantity detection means), 105 ... Output signal judgment part (1st judgment) Means to third judgment means), 106 ... joining state judgment section (allowability judgment means), 108 ... stop control section (stop means), A1, B1 ... upper management limit, A2, B2 ... lower management limit, P2 ... difference signal , S... Output signal, S1... Pre-stage part, S2... Rising part, S3.

Claims (8)

A friction welding system comprising a driving means for driving a friction member so that friction heat is generated in a joint portion of a metal material to be joined,
Physical quantity detecting means for detecting a change in physical quantity related to the amount of energy supplied to the system from the start to completion of friction welding;
Of the output signals from the physical quantity detection means, the rising portion when the friction member driven by the driving means contacts the joint is the upper control limit value of the rising portion of the reference output signal set in advance. First determination means for determining whether or not there is an abnormality in the rising portion based on whether or not it falls within a lower management limit value;
Of the output signals from the physical quantity detection means, a moving average is calculated for a subsequent portion until the driving of the friction member stops, and a difference signal obtained by subtracting the moving average from the output signal of the subsequent portion is obtained in advance. Second determination means for determining whether there is an abnormality in the subsequent portion based on whether or not a set threshold value is exceeded;
A friction welding system comprising: a judgment unit for judging whether or not the joining state of the joint portion is acceptable based on a judgment result by the first judgment unit and the second judgment unit.   The friction welding system according to claim 1, further comprising a stopping unit that stops the driving unit when the first determining unit determines that there is an abnormality in the rising portion.   Of the output signals from the physical quantity detection means, the previous stage from when the friction member is driven by the drive means until the friction member comes into contact with the joint is the previous stage of the preset reference output signal. 2. The apparatus according to claim 1, further comprising third determination means for determining whether or not there is an abnormality in the preceding portion based on whether or not the upper management limit value is within a lower management limit value. 2. The friction welding system according to 2.   4. The friction welding system according to claim 3, further comprising a stopping unit that stops the driving unit when the third determining unit determines that there is an abnormality in the front portion. A friction joining method comprising a step of driving a friction member by a driving means so that friction heat is generated in a joint portion of a metal material to be joined,
A physical quantity detection step for detecting a change in physical quantity related to the amount of energy supplied to the system by a physical quantity detection means from the start to completion of friction welding;
Among the output signals from the physical quantity detection means, the rising portion when the friction member driven by the driving means comes into contact with the metal material is the upper management limit value of the rising portion of the preset output signal for reference. A first determination step of determining whether or not there is an abnormality in the rising portion based on whether or not it falls within a lower management limit value;
Of the output signals from the physical quantity detection means, calculate a moving average for the subsequent portion until the driving of the friction member stops, and a difference signal obtained by subtracting the moving average from the output signal of the subsequent portion; A second determination step of determining whether there is an abnormality in the subsequent portion based on a comparison with a preset threshold;
A friction joining method comprising: a judgment step for judging whether or not the joining state of the joint portion is possible based on the judgment results of the first judgment step and the second judgment step.   6. The friction joining method according to claim 5, further comprising a stopping step of stopping the driving means when it is determined in the first determining step that there is an abnormality in the rising portion.   Of the output signals from the physical quantity detection means, the previous stage from when the friction member is driven by the drive means until the friction member comes into contact with the joint is the previous stage of the preset reference output signal. 6. The method according to claim 5, further comprising a third determination step of determining whether or not there is an abnormality in the preceding portion based on whether or not the upper management limit value and the lower management limit value are within the range. 6. The friction joining method according to 6.   8. The friction welding method according to claim 7, further comprising a stopping unit that stops the driving unit when it is determined in the third determining step that there is an abnormality in the preceding stage portion.

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