JP2009082949A - Friction stir welding system and friction stir welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stir welding system and a friction stir welding method, which can detect an omen of a damage of a rotary tool with high accuracy. <P>SOLUTION: In the friction stir welding system 1, the omen of the damage of the rotary tool 3 is detected by counting how many times a wave pattern M in an output signal for measuring detected by an acceleration detecting sensor 201 intersects sample lines H1 and H2 within a predetermined time and judging whether the number exceeds a predetermined number. The predetermined time for counting the intersection number is set at a time for the rotary tool 3 to rotate several times considering that a period of the wave pattern M of the measuring output signal synchronizes with a revolution period of the rotary tool 3. By this way, the omen part M2 appearing in several periods can be caught clearly and the omen of the damage of the rotary tool 3 can be judged with high accuracy. <P>COPYRIGHT: (C)2009,JPO&INPIT

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. Then, two metals are joined by plastic flow using frictional heat generated by pushing a probe provided at the tip of the rotary tool into the joint and rotating it at high speed.

In such friction stir welding, a considerable load is applied to the rotating tool during welding. Therefore, when the conditions such as the feed rate are inconsistent or when the joining is repeatedly performed, the rotary tool may be greatly deformed (damaged). For such a problem, for example, in the friction stir welding method described in Patent Document 1, tool breakage is detected by monitoring the torque applied to the rotating spindle. When the tool breakage is detected, the tool is retracted from the metal material.
JP 2004-298900 A

  However, even if the rotary tool is retracted from the metal material after the rotary tool has been completely damaged, the joining state of the joint portion may deteriorate at the damaged portion of the rotary tool. Also, the longer the time from when the rotating tool is completely damaged until the rotating tool is stopped, the more likely it is that secondary damage will occur in each part of the system. Therefore, in the friction stir welding system, a technique capable of accurately detecting a sign of damage to the rotary tool has been required.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a friction stir welding system and a friction stir welding method capable of accurately detecting a sign of breakage of a rotary tool.

  In order to solve the above problems, the inventors of the present application paid attention to the characteristics of the material of the rotary tool used in the friction stir welding in the course of earnest research. As a result, it has been found that a ductile material such as a metal that is frequently used as a material for a rotating tool has a characteristic that a certain preliminary deformation occurs immediately before complete failure occurs. Therefore, the inventors of the present application can accurately detect a sign of the rotating tool before it breaks by adding a certain process to the physical quantity that changes in relation to the preliminary deformation of the rotating tool. The inventors have obtained knowledge and have come up with the present invention.

  The friction stir welding system according to the present invention is a friction stir welding system that joins metal materials by pushing a rotary tool made of a ductile material into the abutting portion between end surfaces of metal materials and rotating the rotary tool, Physical quantity detection means for detecting a change in physical quantity related to the deformation state of the rotating tool, a waveform pattern of an output signal output from the physical quantity detection means, and an output signal output when no deformation of the rotating tool is seen from the physical quantity detection means Predictive judgment that compares a sample line set in advance based on the standard deviation of the waveform pattern and determines whether there is a sign of breakage in the rotating tool based on the number of times the waveform pattern intersects the sample line within a predetermined time If the rotating tool is judged to have a sign of breakage by the means and the sign determining means, the rotating tool can be turned to be a metal material. Is separated, characterized in that a control means for stopping the subsequent rotation of the rotary tool.

  Further, the friction stir welding method is a friction stir welding method in which a metal tool is joined by pushing a rotary tool made of a ductile material into the abutting portion between the end faces of the metal material and rotating the rotary tool. When the means detects the change of the physical quantity related to the deformation state of the rotating tool, and the predictor judging means does not see the waveform pattern of the output signal output from the physical quantity detecting means and the deformation of the rotating tool from the physical quantity detecting means. Is compared with the sample line set in advance based on the standard deviation of the waveform pattern of the output signal output to the output signal, and based on the number of times the waveform pattern intersects the sample line within the predetermined time, The step of determining the presence / absence of the rotary tool is determined when the control means determines that the rotary tool has a sign of damage. While keeping rolling is separated from the metal material, characterized by comprising the step of stopping the subsequent rotation of the rotary tool.

  In this friction stir welding system and friction stir welding method, in order to detect a sign of breakage of the rotary tool, a change in physical quantity related to the deformation state of the rotary tool is detected by a physical quantity detection means. When an abnormality occurs in the rotary tool, the waveform pattern of the output signal from the physical quantity detection means behaves in such a way that the amplitude increases from the normal state over a plurality of cycles in response to preliminary deformation before the rotary tool is damaged. After that, the amplitude further increases momentarily in synchronism with the breakage of the rotating tool. Therefore, the waveform pattern of the output signal from the physical quantity detection means is compared with a preset sample line, and the number of times the waveform pattern intersects the sample line within a predetermined time is counted, so that a preliminary tool before the rotary tool is damaged can be obtained. The behavior of the waveform pattern appearing over a plurality of periods corresponding to the deformation can be detected without error. Further, in this friction stir welding system and friction stir welding method, when it is determined that there is a sign of damage to the rotating tool, the rotating tool is separated from the metal material while being rotated, and then the rotating tool is stopped. As a result, it is possible to prevent welding between the rotating tool and the metal material in which signs of damage are recognized. By stopping the rotating tool before it completely breaks, secondary damage to the system can be avoided.

  Moreover, it is preferable that the predetermined time is a time during which the rotating tool rotates at least a plurality of times. The period of the waveform pattern of the output signal from the physical quantity detection means corresponds to the rotation period of the rotary tool. Therefore, by setting the time for which the rotating tool rotates at least a plurality of times as a predetermined time, it is possible to more reliably detect the behavior of the waveform pattern that appears over a plurality of periods corresponding to the deformation of the rotating tool before the breakage.

  Preferably, the apparatus further comprises a tool station in which a plurality of rotating tools are set, and a transfer means for transferring the rotating tool to the tool station after the rotation of the rotating tool is stopped by the control means. In this case, since the rotating tool in which the sign of damage is recognized is quickly replaced with another rotating tool, the time until the friction stir welding is restarted is shortened, and the working efficiency can be maintained.

  According to the friction stir welding system and the friction stir welding method according to the present invention, it is possible to accurately detect a sign of breakage of the rotary tool.

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

  FIG. 1 is a perspective view illustrating friction stir welding using a friction stir welding system according to an embodiment of the present invention. In the example illustrated in FIG. 1, for example, the outer plates 10 a and 10 b of a railway vehicle are joined together. The outer plates 10a and 10b are flat plate materials made of, for example, stainless steel and having a thickness of about several millimeters. As shown in FIG. 1, the friction stir welding system 1 includes a placement unit 2, a rotating tool 3, and a tool holder 4 as components for joining the outer plates 10 a and 10 b. The rotary tool 3 is formed of a ductile material such as metal and has a substantially cylindrical shape. A substantially cylindrical probe 5 having a diameter smaller than the diameter of the rotary tool 3 is coaxially provided at the tip of the rotary tool 3. The tool holder 4 is made of a ductile material such as metal and has a substantially cylindrical shape. Inside the tool holder 4, a substantially cylindrical internal space S substantially the same as the diameter of the rotary tool 3 is formed along the long axis direction (see FIG. 3). The upper portion of the rotary tool 3 is inserted into the lower end portion of the internal space S, whereby the rotary tool 3 is held by the lower end portion 4 a of the tool holder 4.

  In the friction stir welding using the friction stir welding system 1, the end faces of the outer plates 10 a and 10 b placed on the placement unit 2 are brought into contact with each other, and the outer plate 10 a, while rotating the rotary tool 3 at a rotational speed of 600 rpm, for example. Push into one end of the butt portion L of 10b. Then, the rotary tool 3 is moved along the butted portion L at a moving speed of, for example, 600 mm / min. At this time, the joint portion W is formed by plastic flow due to frictional heat generated between the rotating tool 3 and the outer plates 10a and 10b, and the end surfaces of the outer plates 10a and 10b are joined along the abutting portion L. The When the rotating tool 3 reaches the other end of the abutting portion L of the outer plates 10a and 10b, the rotating tool 3 is pulled up from the outer plates 10a and 10b, and the rotating tool 3 is separated from the outer plates 10a and 10b. To do.

  In such friction stir welding, the rotary tool is used when the moving speed condition of the rotary tool 3 is inconsistent with the thickness of the outer plates 10a and 10b to be joined, or when the joining is repeated. As a result, an excessive load accumulates on the rotary tool 3, and a large distortion (breakage) may occur in the rotary tool 3 made of a ductile material. When such a breakage of the rotary tool 3 occurs, the joining state of the joint portion W may be deteriorated at the damaged portion of the rotary tool 3. In addition, the longer the time from when the rotating tool 3 is completely damaged until the rotating tool 3 is stopped, the higher the possibility that secondary damage will occur in each part of the system.

  Therefore, in the friction stir welding system 1, as shown in FIG. 2, an acceleration detection sensor (physical quantity detection means) 201, an output signal acquisition unit, as functional components for detecting a sign of damage to the rotary tool 3 are provided. 202, a sample line storage unit 203, a sign determination unit (prediction determination unit) 204, a control unit (control unit) 205, and a transfer unit (transfer unit) 206.

  The acceleration detection sensor 201 is a sensor that detects the acceleration of the rotary tool 3 as a physical quantity related to the deformation state of the rotary tool 3. FIG. 3 is a diagram illustrating an example of an arrangement configuration of the acceleration detection sensor 201. As shown in the figure, the acceleration detection sensor 201 is disposed in the internal space S of the tool holder 4 and is in contact with the upper end surface 3 a of the rotary tool 3 held by the lower end portion 4 a of the tool holder 4. 4 is bonded and fixed to the inner wall.

  The cable 8 of the acceleration detection sensor 201 extends above the internal space S of the tool holder 4, and the tip 9 of the cable 8 is fixed to the inner wall of the tool holder 4 at the upper end portion of the internal space S. For example, a crimp terminal is used to fix the tip 9 of the cable 8 and the inner wall of the tool holder 4. With such a configuration, the acceleration detection sensor 201 detects the vertical acceleration applied to the rotary tool 3, and outputs an output signal for measurement corresponding to the detected acceleration via the electrodes 7a and 7b of the slip ring 6. The data is output to the acquisition unit 202.

  The output signal acquisition unit 202 is a part that acquires an output signal for measurement corresponding to the acceleration detected by the acceleration detection sensor 201. The output signal acquisition unit 202 converts the acquired output signal for measurement into a waveform pattern and outputs the waveform pattern to the sign determination unit 204.

  The sample line storage unit 203 is a part that stores a sample line used as a threshold value when determining whether or not there is a sign of damage in the rotary tool 3. The sample line is calculated in advance using a reference output signal output from the acceleration detection sensor 201 when there is no abnormality such as deformation in the rotary tool 3 during joining. FIG. 4 is a diagram illustrating an example of a waveform pattern of a reference output signal. In the example shown in FIG. 4, the waveform pattern R of the reference output signal has a uniform amplitude from the start to the end of the friction stir welding at a cycle corresponding to the rotation cycle of the rotary tool 3. The sample line storage unit 203 normalizes the waveform pattern R of the reference output signal based on the standard deviation σ, and, as shown in FIG. 5, for example, three times (± 3σ) of the standard deviation σ is sample lines H1, H2. As stored.

  The sign determination unit 204 is a part that determines whether there is a sign of damage in the rotary tool 3. Here, FIG. 6 is a diagram showing a waveform pattern of an output signal for measurement when the rotary tool 3 is broken during joining. In the example shown in FIG. 6, the waveform pattern M of the output signal for measurement includes a normal part M1 before an abnormality occurs in the rotary tool 3, a sign part M2 indicating a sign of damage to the rotary tool 3, and a rotation tool 3 A broken portion M3 showing complete breakage appears.

  In the normal part M1, similarly to the reference waveform pattern R, the amplitude is uniform in a period corresponding to the rotation period of the rotary tool 3. The sign portion M2 shows a behavior in which the amplitude almost doubles compared to the normal portion M1 over a plurality of periods. The damaged portion M3 shows a behavior in which the amplitude is instantaneously doubled compared to the predictive portion M2.

  The sign determination unit 204 determines whether or not there is a sign of damage in the rotating tool 3 based on the number of times the waveform pattern M intersects the sample lines H1 and H2 while the rotating tool 3 rotates a plurality of times. For example, as shown in FIG. 7, the sign determination unit 204 causes the rotary tool 3 to be damaged when the sign portion M2 appears in the waveform pattern M and the waveform pattern M and the sample lines H1 and H2 intersect, for example, ten times. Judge that there is a sign. On the other hand, the sign determination unit 204 has no sign portion M2 in the waveform pattern M, and the rotating tool 3 has a sign of damage as long as the number of intersections between the waveform pattern M and the sample lines H1 and H2 does not exceed 10. Do not judge. The sign determination unit 204 does not perform any special processing until it is determined that there is a sign of breakage, and if it is determined that there is a sign of breakage in the rotary tool 3, determination result information indicating that is sent to the control unit 205. Output.

  The control unit 205 is a part that controls the rotary tool 3 based on the determination result information received from the sign determination unit 204. When receiving the determination result information, the control unit 205 first separates the rotary tool 3 from the outer plates 10a and 10b, and then stops the rotation of the rotary tool 3. When the rotation of the rotary tool 3 is stopped, the control unit 205 outputs operation instruction information to the transfer unit 206.

  The transfer unit 206 is a part that transfers the rotary tool 3 to the tool station 30. In the tool station 30, for example, a plurality of unused rotary tools 12 each having a probe 15 at the tip are set (see FIG. 10). When receiving the operation instruction information from the control unit 205, the transfer unit 206 transfers the rotary tool 3 from the outer plates 10a and 10b being joined to the tool station 30. In the tool station 30, the rotating tool 3 that has been confirmed to be damaged is removed from the tool holder 4, and a new rotating tool 12 is attached to the tool holder 4. After the exchange of the rotary tool 3 at the tool station 30, the transfer unit 206 returns the rotary tool 3 onto the outer plates 10a and 10b.

  Next, the operation of the friction stir welding system 1 having the above-described configuration will be described with reference to FIG. FIG. 8 is a flowchart showing the operation of the friction stir welding system 1.

  First, the rotary tool 3 is pushed into one end of the outer plates 10a and 10b while rotating, and friction stir welding is started (step S01). While performing the joining, the acceleration detection sensor 201 detects the acceleration of the rotary tool 3 (step S02). The output signal acquisition unit 202 acquires an output signal for measurement output from the acceleration detection sensor 201, and forms a waveform pattern of the output signal with respect to the time axis (step S03).

  Next, the sign determination unit 204 compares the waveform pattern M for measurement received from the output signal acquisition unit 202 with the sample lines H1 and H2 stored in the sample line storage unit 203, and breaks the rotating tool 3. It is determined whether or not there is a precursor (step S04). The sign determination unit 204 determines that the rotary tool 3 has a sign of damage when the sign portion M2 appears in the waveform pattern M and the waveform pattern M and the sample lines H1 and H2 intersect, for example, 10 times. On the other hand, the sign determination unit 204 has no sign portion M2 in the waveform pattern M, and the rotating tool 3 has a sign of damage as long as the number of intersections between the waveform pattern M and the sample lines H1 and H2 does not exceed 10. Do not judge.

  If it is determined in step S04 that there is a sign of damage to the rotary tool 3, first, the control unit 205, as shown in FIG. 9A, the outer plate 10a being joined while the rotary tool 3 is rotated. , 10b, and then the rotation of the rotary tool 3 is stopped (step S05).

  After the rotation of the rotary tool 3 is stopped, transfer to the tool station 30 is performed by the transfer unit 206 (step S06). Then, as shown in FIG. 9B, the rotary tool 3 is discarded by the tool discarding unit 20 of the tool station 30.

  When the rotating tool 3 is discarded in the tool discarding unit 20, the tool station 30 rotates clockwise, and the new rotating tool 12 is disposed directly below the tool holder 4. When the tool holder 4 is lowered and a new rotating tool 12 is mounted on the tool holder 4, the transfer unit 206 transfers the rotating tool 12 above the outer plates 10a and 10b as shown in FIG. Then, the rotary tool 12 is returned to the interruption position Wa of the friction stir welding. Thereafter, as shown in FIG. 10B, the rotary tool 12 is rotated and pushed into the interruption position Wa in the outer plates 10a and 10b, and the friction stir welding is resumed (step S08).

  On the other hand, if it is not determined in step S04 that there is a sign of damage to the rotary tool 3, and if welding is resumed in step S08, the friction stir welding is continued and the friction stir welding is completed. It is determined whether or not (step S09). While the friction stir welding is continued, the above-described series of processing from step S02 to step S09 is repeated. When the rotary tool 3 reaches the other end of the outer plates 10a and 10b and the friction stir welding is finished, the friction stir welding system 1 separates the rotary tool 3 from the outer plates 10a and 10b and stops the rotation of the rotary tool 3. Then, the process is terminated.

  As described above, the friction stir welding system 1 counts the number of times that the waveform pattern M of the output signal for measurement detected by the acceleration detection sensor 201 intersects the sample lines H1 and H2 within a predetermined time. Is detected, a sign of breakage of the rotary tool 3 is detected. Also, paying attention to the fact that the cycle of the waveform pattern M of the output signal for measurement is synchronized with the rotation cycle of the rotary tool 3, the predetermined time for counting the number of crossings is set as the time for which the rotary tool 3 rotates a plurality of times. It is set. As a result, the sign portion M2 appearing over a plurality of cycles can be clearly grasped, and the sign of breakage of the rotary tool 3 can be accurately determined.

  Further, in the friction stir welding system 1, when a sign of damage to the rotary tool 3 is detected, the rotary tool 3 is separated from the outer plates 10a and 10b while being rotated. Therefore, the rotary tool 3 and the outer plates 10a and 10b Can be prevented. Further, by executing such processing before the rotary tool 3 is completely damaged, the rotary tool 3 distorted by deformation is prevented from rotating while being pushed into the outer plates 10a and 10b, and the rotary tool is prevented. Therefore, it is possible to prevent deterioration of the joining state of the joint portion W at the position where the sign of 3 damage is recognized. Furthermore, it is possible to avoid the occurrence of secondary damage to the system due to an excessive load on the tool holder 4 or the like.

  Further, when a sign of damage of the rotary tool 3 is detected, the rotary tool 3 is transferred to the tool station 30 by the transfer unit 206. Thereby, since the rotary tool 3 in which the sign of damage is recognized is immediately replaced with the unused rotary tool 12, the time until the friction stir welding is restarted is shortened, and the working efficiency can be maintained.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the acceleration detection sensor 201 detects the acceleration of the rotary tool 3 and analyzes the waveform pattern of the output signal. In addition to the acceleration detection sensor 201, a load detection sensor is arranged, The waveform pattern of the output signal may be analyzed.

It is a perspective view explaining the friction stir welding using the friction stir welding system which concerns on one Embodiment of this invention. It is a figure which shows the functional component of the friction stir welding system shown in FIG. It is a figure which shows an example of the arrangement configuration of an acceleration detection sensor. It is a figure which shows the waveform pattern of the output signal for a reference | standard. FIG. 5 is a diagram showing a sample line calculated from the waveform pattern of the reference output signal shown in FIG. 4. It is a figure which shows the waveform pattern of the output signal for a measurement when damage occurs to a rotary tool. It is a figure which shows the judgment of the precursor of the failure | damage of a rotary tool. It is a flowchart which shows operation | movement of the friction stir welding system shown in FIG.1 and FIG.2. It is a figure which shows operation | movement of the friction stir welding system when the sign of damage is recognized by the rotary tool. FIG. 10 is a diagram illustrating a subsequent operation of FIG. 9.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Friction stir welding system, 3 ... Rotation tool, 201 ... Acceleration detection sensor (physical quantity detection means), 204 ... Predictive judgment part (predictive judgment means), 205 ... Control part (control means), 206 ... Transfer part (Transfer means) ), 30 ... tool station, L ... butting portion, H1, H2 ... sample line, M, R ... waveform pattern.

Claims (6)

A friction stir welding system that joins the metal materials by pushing the rotary tool made of a ductile material into the abutting portion between the end faces of the metal material and rotating the rotary tool,
Physical quantity detection means for detecting a change in physical quantity relating to the deformation state of the rotating tool;
A sample set in advance based on the waveform pattern of the output signal output from the physical quantity detection means and the standard deviation of the waveform pattern of the output signal output when no deformation of the rotating tool is seen from the physical quantity detection means A sign judging means for judging whether or not there is a sign of breakage in the rotating tool based on the number of times the waveform pattern intersects the sample line within a predetermined time;
Control means for separating the rotating tool from the metal material while rotating the rotating tool and then stopping the rotation of the rotating tool when the sign determining means determines that the rotating tool has a sign of damage. A friction stir welding system comprising:   The friction stir welding system according to claim 1, wherein the predetermined time is a time during which the rotating tool rotates at least a plurality of times. A tool station with multiple rotation tools set;
The friction stir welding system according to claim 1, further comprising transfer means for transferring the rotary tool to the tool station after rotation of the rotary tool is stopped by the control means. A friction stir welding method for joining the metal materials by pushing the rotary tool made of a ductile material into the abutting portion between the end faces of the metal material and rotating the rotary tool,
A physical quantity detection means for detecting a change in physical quantity related to the deformation state of the rotary tool;
Based on the standard deviation of the waveform pattern of the output signal output from the physical quantity detection means and the waveform pattern of the output signal output when no deformation of the rotating tool is seen from the physical quantity detection means. Comparing with a preset sample line, and determining based on the number of times the waveform pattern intersects the sample line within a predetermined time, whether there is a sign of damage in the rotating tool;
When it is determined by the sign determining means that the rotary tool has a sign of damage, the control means causes the rotary tool to rotate away from the metal material, and then stops the rotation of the rotary tool. And a friction stir welding method comprising: a step.   The friction stir welding method according to claim 4, wherein the predetermined time is a time during which the rotating tool rotates at least a plurality of times. The transfer means further comprises a step of transferring the rotary tool to a tool station in which a plurality of rotary tools are set after rotation of the rotary tool is stopped by the control means. 5. The friction stir welding method according to 5.

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