JP4772260B2 - Friction stir welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a friction stir welding apparatus that softens and stirs an object to be joined by frictional heat generated by rotation and joins the objects by stirring.
[0002]
[Prior art]
Automotive aluminum body joining methods include spot welding for aluminum, rivet joining, etc., but piping and utilities on the robot machine are complicated, and there are problems such as poor working environment such as generation of loud noise and sparks. . In view of such a problem, a spot welding apparatus using friction stir welding has been proposed.
[0003]
In friction stir welding, spot welding is performed by pressing against a workpiece that is a workpiece while rotating a rotor having a pin at the tip at high speed, and friction stir.
[0004]
[Problems to be solved by the invention]
The spot welding device using friction stir welding can be applied to an existing spot welding gun that is resistance welding, but in spot welding, the electrode was not rotated. It cannot be applied to a spot welding apparatus using friction stir welding.
[0005]
Further, the conventional spot welding gun performs servo control of the applied pressure. That is, the pressure is detected in real time during the joining operation, and feedback control is performed so as to obtain a motor current corresponding to the force. Such control is not particularly problematic in terms of joining quality as current spot welding control.
[0006]
On the other hand, in friction stir welding, there is also a unique behavior characteristic due to the phenomenon related to frictional heat called friction stir welding, and its definition has just begun by related parties, and a control method for friction stir welding has not been proposed yet. .
[0007]
Therefore, a method of applying the existing spot welding servo control to the control of the friction stir welding can be considered. That is, during the joining operation, the rotation speed is monitored in real time, and feedback control is always performed so that the optimum rotation speed is obtained. Furthermore, a method of monitoring the applied pressure in real time and performing feedback control so that the optimum applied pressure is always obtained can be considered. However, the servo control of the rotational speed and the pressure control in this way is very complicated and difficult to realize.
[0008]
An object of the present invention is to provide a friction stir welding apparatus capable of performing friction stir spot welding with simple control and practically no problem.
[0009]
[Means for Solving the Problems]
The present invention moves the rotor that rotates at high speed straight in the direction of the rotation axis, presses the tip portion against the object to be joined, and softens it by frictional heat between the tip part and the contact part between the article to be joined, In the friction stir welding apparatus that stirs and spot-joins the workpieces,
A rotation control means for changing and controlling the rotation speed of the rotor as time elapses during the friction stir welding operation;
A friction stir welding apparatus comprising: a linear movement control means for controlling a pressure during a friction stir welding operation by moving a rotor straight.
[0010]
According to the present invention, since the rotation control means is provided, the rotation speed of the rotor can be variably controlled. As a result, spot bonding can be performed at an optimum rotational speed. Further, the straight-ahead control means can perform fine control of the applied pressure, and can be joined with the optimum applied pressure for spot joining.
[0011]
Further, the present invention is characterized in that the rotation control means changes the rotation speed so as to decrease with time during the friction stir welding operation.
[0012]
Further, the present invention is characterized in that the rotation control means changes so as to increase the rotation speed as time elapses during the friction stir welding operation.
[0013]
  Further, in the present invention, the rotation control means can adjust the rotation speed as time passes during the friction stir welding operation.To drop once during the pressing periodIt is characterized by changing.
[0014]
Further, the present invention is characterized in that the rotation control means changes the rotation speed stepwise or continuously.
[0015]
  According to the present invention, during the friction stir welding operation, the rotation control means changes the rotation speed of the rotor 22 so as to decrease or increase over time, or alternativelyTo drop once during the pressing periodThe speed change is performed stepwise or continuously, so that the friction stir welding of the workpieces to be joined can be performed under the optimum conditions, and the joint strength can be improved. Can be planned.
[0016]
In the present invention, the straight-ahead control means is
In the initial stage of the friction stir welding operation, a speed command value having a shape having an inclined portion that increases the speed of the rotor 22 as time elapses is derived.
[0017]
According to the present invention, the shape of the speed command value is a triangular wave shape.
[0018]
  According to the present invention, since the speed command value given from the linear control means to the linear motor 24 which is a linear drive source is, for example, a triangular wave shape, the tip of the rotor 22 abruptly collides with a workpiece which is a workpiece. Therefore, it is possible to prevent the workpiece from vibrating and to achieve accurate friction stir welding.
  Further, the present invention is characterized in that the rotation speed is changed by the rotation control means in a state in which the applied pressure is kept constant by the straight advance control means..
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing the structure of a spot welding gun 20 which is an embodiment of the friction stir welding apparatus of the present invention. The spot welding gun 20 is mounted on the wrist of a 6-axis vertical articulated robot, for example, and is used when spot welding an aluminum alloy workpiece such as an aluminum body of an automobile by a friction stir method.
[0020]
The spot bonding gun 20 is attached to a rotor 22, a wrist of the robot, and a gun arm 21 that functions as a support member that supports the rotor 22, a rotation motor 25 that rotationally drives the rotor 22, and a linear motor 24 that linearly moves. The rotation transmission means 30 for transmitting the rotational force of the rotation motor 25 to the rotor 22 and the ball screw 50 and the linear transmission means 45 and the control device 10 for transmitting the linear movement force of the linear movement motor 24 to the rotor 22 are provided. Prepare.
[0021]
Each joint axis of the robot is driven by six servomotors of the first axis to the sixth axis, the seventh axis is a linear motor 24 of the spot welding gun 20, and the eighth axis is a rotation motor 25. (The 8th axis may be referred to as a turning axis). These servo motors are controlled by the control device 10. That is, the linear motor 24 is controlled by the linear controller 11 of the control device 10, and the rotary motor 25 is controlled by the rotation controller 12 of the controller 10, and the first to sixth motors of the robot. Although not shown, each is controlled by a corresponding control unit of the control device 10.
[0022]
The rotor 22 has a truncated cone shape, and is attached to the gun arm 21 so as to be rotatable about the center axis line as the rotation axis line L with the tip portion thereof downward. A cylindrical shoulder portion 51 is formed at the tip of the rotor 22, and a cylindrical pin 52 having the rotation axis L as an axis projects downward from the lower end surface of the shoulder portion 51. Further, the rotor 22 can be moved up and down along the rotation axis L.
[0023]
The gun arm 21 has a rotation motor 25 and a linear motor 24 realized by a servo motor fixed to the upper part, a lower part bent in an L shape, and a receiving part 23 fixed to the tip part. The receiving portion 23 has a cylindrical shape, and is arranged with the rotation axis L as the axis and the upper end surface facing the tip of the rotor 22.
[0024]
The rotor 22 is detachably held on the head 40, and the head 40 is supported by the head support portion 41 via the bearing 70 so as to be rotatable around the rotation axis L. A rotation shaft 26 extending upward along the rotation axis L is fixed to the rotor 22, and thus the head 40. In addition, an outer cylinder that extends upward along the rotation axis L and through which the rotation shaft 26 is inserted is fixed to the head support portion 41. This outer cylinder functions as a screw shaft 27 having a male screw of the ball screw 50. Therefore, by moving the screw shaft 27 up and down with the linear motor 24 while rotating the rotary shaft 26 with the rotary motor 25, the rotor 22 can be moved linearly while rotating.
[0025]
Next, the configuration of the rotation transmission means 30 that transmits the rotation of the rotation motor 25 to the rotation shaft 26 will be described. The rotation transmitting means 30 has a mechanism that allows the rotation of the rotation shaft 26 to which the rotor 22 is coupled in the direction of the rotation axis L and transmits the rotation of the rotation motor 25 to the rotor 22. A belt wheel 31 fixed to the output shaft 25, a belt wheel 32 connected to the rotary shaft 26, and an annular timing belt 33 wound around the belt wheels 31 and 33. The belt wheel 32 and the rotation shaft 26 are, for example, spline-coupled, and the rotation of the belt wheel 32 and the rotation shaft 26 around the rotation axis L is restricted, and movement in the direction of the rotation axis L is allowed. Therefore, by rotating the rotation motor 25, the rotor 22 can be rotationally driven so as to be movable in the direction of the rotation axis L.
[0026]
Next, the configuration of the straight transmission means 45 will be described. The linear transmission means 45 includes a ball screw 50 including a screw shaft 27 and a nut member 28, a belt wheel 46 fixed to the output shaft of the linear motor 24, a belt wheel 48 fixed to the nut member 28, and a belt wheel 46. , 48 has an annular timing belt 47 wound around. The screw shaft 27 of the ball screw 50 is hollow as described above, and the rotation shaft 26 passes freely inside. The screw shaft 27 is supported by the gun arm 21 by a retainer 55. The retainer 55 has a plurality of balls, holds the screw shaft 27 so that the screw shaft 27 can be displaced in the direction of the rotation axis L, and the rotation around the rotation axis L is restricted. A nut member 28 is provided under the retainer 55. A screw groove is formed in the outer periphery of the screw shaft 27, and the nut member 28 is screwed into the screw groove.
[0027]
  The nut member 28 is attached to the gun arm 21 via a bearing., TimesIt is rotatably supported around the rotation axis L. A belt wheel 48 is fixed to the lower part of the nut member 28, and the belt wheel 48 and the nut member 28 rotate together. Therefore, when the linear motor 24 is rotated, the nut member 28 is rotated via the timing belt 48. When the nut member 28 rotates, the screw shaft 27 moves up and down in the direction of the rotation axis L. A head support portion 41 is fixed to the lower end portion of the screw shaft 27, and a head 40 that holds the rotor 22 is rotatably connected to the head support portion 41.
[0028]
By using the rotation transmission means 30 and the straight transmission means 45 as described above, the rotor 22 can be moved straight along the rotation axis L while rotating the rotor 22 around the rotation axis L by the motor 25 for rotation. The spot bonding gun 20 can be opened and closed by moving up and down by a motor.
[0029]
Next, a control method at the time of spot bonding by the control device 10 will be described with reference to the flowcharts of FIGS. 2 and 3 and the timing chart of FIG. 4. 4 (1) shows the applied pressure, (2) is the speed command value to the linear motor (seventh axis) 24, and (3) is the movement displacement command value to the linear motor 24. is there. The differential value of the speed command value (2) becomes the movement displacement command value (3). Conversely, the integral value of the movement displacement command value (3) becomes the speed command value (2). (4) is a rotation speed command value to the rotation motor (eighth axis) 25.
[0030]
In the spot joining operation, for example, two workpieces having a thickness of about 2 mm are spot joined. Here, it is assumed that the workpieces are made of an aluminum alloy, and two pieces are overlapped substantially horizontally, and there are a plurality of joints per workpiece.
[0031]
When the spot bonding control is started, first, in step S1, the spot bonding gun 20 is positioned at the position P1. The position P1 refers to the position where the tip of the pin 52 of the rotor 22 is disposed at a position (for example, 50 mm above) separated from the joining hit point P2 by a predetermined distance when the workpiece joining point is the joining hit point P2. It is a position where the receiving part 23 of the spot bonding gun 20 is disposed at a position below the workpiece by a predetermined distance downward.
[0032]
Next, in step S2, the closing operation of the bonding gun 20 is started. That is, at time t1, as shown in FIGS. 4 (2) and 4 (3), the speed command value and the movement displacement command value are output to the straight-ahead motor 24. The reason why the speed command value to the linear motor 24 is a triangular wave is to prevent the workpiece from vibrating due to the rotor tip suddenly colliding with the workpiece.
[0033]
Further, since the spot bonding gun 20 is closed only by moving the rotor 22 straightly and the receiving portion 23 is fixed, in order to sandwich the workpiece in the vertical direction, the rotor 22 is lowered and the robot uses a gun. 20 needs to be raised. Therefore, in the closing operation of step S2, the rotor 22 is lowered by the linear motor 24, and the gun 20 is moved along the rotation axis L direction of the rotor 22 using the robot 6 axis. Let In this way, the robot 6 axis is controlled so that the point in time when the rotor tip abuts on the workpiece coincides with the point in time when the receiving portion 23 abuts under the workpiece.
[0034]
Next, in step S3, rotation of the rotor 22 is started (time t2).
In the next step S4, when the joining hit point P2 is reached (time t3), that is, when the tip of the pin 52 of the rotor 22 contacts the work, pressurization is started in step S5. Thereafter, in step S6, the rotation control unit 12 determines whether or not the rotation motor 25 is within a predetermined rotation speed range.
[0035]
In this embodiment, this determination is performed once during the pressurization of the joining operation, and the instantaneous value of the rotation speed is detected by the rotation control unit 12 at any timing during the pressurization. In the present embodiment, as shown in FIG._LThen, the central time point, that is, the pressurization start time t3 to t_LWhen / 2 has elapsed, the instantaneous value of the rotational speed is detected. For example, the rotational speed is designated as 3000 rpm, and the predetermined rotational speed range is, for example, within ± 10%, preferably within ± 5% of the designated rotational speed. Alternatively, the range may be set with the rotation speed within ± X rpm instead of%.
[0036]
If the rotational speed is not within the predetermined range, it is determined that the rotational motor is abnormal in step S7 as a rotational motor abnormality (eighth axis), and a robot abnormality signal is output. In step S8, the first to second axes are output. Stop all the 8-axis motors and stop the robot.
[0037]
If it is determined in step S6 that it is within the predetermined rotation speed range, the process proceeds to step S9, where the linear control unit 11 detects the instantaneous value of the applied pressure and determines whether it is within the specified applied pressure range. To do. For example, when the pressing force is specified as 2.94 kN (300 kg), the predetermined pressing force range is within ± 5%, preferably within ± 1%. Alternatively, the range may be set not by% but by a pressure within YkN. The instantaneous value of the applied pressure is detected by detecting the current value of the linear motor (seventh axis) 24 by the linear controller 11 and instantaneously comparing the actual motor load current with the registered data. In this way, when it is determined that the pressure is not within the predetermined pressure range, a robot abnormality signal is output in step S10 as a pressure axis (seventh axis) pressure abnormality, and the first to second axes in step S8. Stop all 8-axis motors.
[0038]
If it is determined in step S9 that the pressure is within the predetermined pressure range, the process proceeds to step S11. In step S11, the rotation control unit 12 changes the rotation speed as shown in FIG. In the friction stir welding, it is possible to improve the bonding quality by rotating at a high speed at the beginning of the joining and rotating at a low speed at the end of the joining, rather than stirring at a constant rotational speed from the beginning to the end of joining. In the present embodiment, as shown in FIG. 4 (4), the rotation speed is switched to three stages, the initial part from the pressurization start time t3 to time t4 is set to high speed rotation, and the intermediate part from time t4 to time t5. Is set to medium speed, and at the end from time t5, the speed is switched to low speed. These are set with separate parameters for a reference rotational speed, here 3000 rpm.
[0039]
When the tip of the pin 52 of the rotor 22 is rotated at a high speed while being pressed against the workpiece, frictional heat is generated between the pin 52 and the workpiece, the joining point is softened, and the pin 52 is inserted into the workpiece. When the pin 52 is inserted, the shoulder portion 51 of the rotor 22 is also pressed against the work surface, and frictional heat is generated here, and the work is softened and stirred. In this way, after stirring at a high speed in the initial part, the rotation speed is reduced at the intermediate part, further stirring is performed at the medium speed, and at the end part, the speed is further reduced and stirring is performed at a low speed.
[0040]
In this manner, after the rotation speed is switched to a low speed with a constant pressing force applied, the process proceeds to step S12. In step S12, for example, a predetermined time from the start of pressurization is measured by an internal timer, and when the predetermined time, for example, 0.5 to 1 second is measured, the machining is completed and an opening operation is started in the next step S13. The time at this time is time t6.
[0041]
In the opening operation, as shown in FIGS. 4 (2) and (3), a speed command value and a movement displacement command value are output from the linear controller 11 to the linear motor 24 so that the rotor 22 is raised. . At this time, the robot 6 axis is also commanded so that the rotor tip and the receiving portion 23 are simultaneously separated from the workpiece.
[0042]
In the next step S14, it is determined whether or not welding has occurred. In this embodiment, the welding occurrence determination is performed by the linear advance control unit 11 and the rotation control unit 12. For example, the current value of the linear advance motor (seventh axis) 24 detected by the linear advance control unit 11 is a specified value (for example, rated torque). If the motor current value of the rotation motor (eighth axis) 25 detected by the rotation control unit 12 is larger than a specified value (e.g., equivalent to X% of the rated torque), the robot It is determined that there is an abnormality, and the process proceeds to step S15. For example, an alarm is issued with a message such as “Welding has been detected” or “A collision or abnormal disturbance has been detected”, and the first to eighth axes are stopped to stop the robot. To do. It should be noted that this welding detection may be based on the determination of only the current value of the straight motor 24 or only the current value of the motor 25 for rotation. You may judge.
[0043]
Then, the work is separated from the rotor. In the separation work, for example, the rotor is pulled up while rotating. The rotation direction of the rotor may be the same as the rotation direction during the stir welding or may be reversed.
[0044]
The pin 52 at the tip of the rotor may be threaded. For example, when the right-hand thread is cut, it is rotated counterclockwise in order to improve the stirring efficiency during joining. That is, it is rotated so that the surrounding base material moves downward by the rotation of the screw. Therefore, in such a case, the rotation direction of the rotor is not reversed during the separation operation, and is set to the same direction as that at the time of joining. As a result, a force acts in a direction in which the surrounding base material moves downward and pulls the rotor apart. When the pin 52 is not threaded, it is preferable that the pin 52 is reversely rotated and pulled apart.
[0045]
If it is determined in step S14 that welding has not occurred, the opening operation is continued in the next step S16, and the opening operation is continued until the tip of the pin 52 of the rotor 22 is separated from the workpiece by a predetermined clearance distance. To do.
[0046]
Then, in the next step S17, it is determined whether or not the joining of all the joining portions of the workpiece has been completed. If not, the process proceeds to step S18 to complete the work for one point, and the next joining point is determined. After setting, the process returns to step S1 to start the joining operation for the next hit point.
[0047]
If it is determined in step S17 that all the joining points of the workpiece have been completed, in step S19, the rotation control unit 12 outputs a speed command value 0 to the rotation motor 25 to stop the rotation. In the next step S20, the rotation control unit 12 determines whether or not the rotation speed of the rotation motor 24 is 0. If the rotation speed is 0, the process proceeds to step S21, and the work for one work is completed. In step S21, if the rotation speed does not reach 0 even after a lapse of a specified time, for example, 2 seconds after outputting the rotation stop command, the process proceeds to step S7, where the rotation motor (eighth axis) 25 is abnormal. The robot is stopped (step S8).
[0048]
In the above-described embodiment, the joining operation within one workpiece is performed without stopping the rotation of the rotor. However, the present invention is not limited to this, and the rotation may be stopped at each joining hit point. You may control so that rotation may not be stopped.
[0049]
In this embodiment, the rotation speed is changed in three stages at the time of pressurization. However, the rotation speed may be two stages, four stages or more, and control is performed so that the rotation speed changes continuously in a stepless manner. May be. Furthermore, in this embodiment, control is performed so that the initial speed is high and the rotational speed is decreased with time. However, the present invention is not limited to this, and depending on the work, the initial speed is low and the rotational speed is increased with time. It is also possible to control so that the initial part is high speed, the intermediate part is low speed, and the end part is high speed again.
[0050]
In the present embodiment, the rotation speed is detected by the pressurizing time t for one joining operation._L, The central time t_LDetected at / 2. In other words, among the three speeds, only the intermediate speed was monitored within a predetermined speed range, but this is not limiting, and when the rotational speed is set in multiple stages, You may control to monitor a rotational speed. In other words, a predetermined rotational speed range is set for each stage, and at the center of each stage, it is monitored whether or not it is within the predetermined rotational speed range. The robot may be stopped as a speed abnormality.
[0051]
In the above-described embodiment, when at least one of the rotational speed and the applied pressure is out of the predetermined range, the joining operation is controlled to be stopped, but the present invention is not limited to this, If either one is within the predetermined range, the joining operation may be continued, and control may be performed so that the joining operation is stopped only when both are out of the predetermined range.
[0052]
As another embodiment of the present invention, control may be performed so as to change not only the rotation speed but also the applied pressure at the time of joining. For example, the pressurization control may be performed such that the pressure is high during high-speed rotation of the initial part, medium pressure during medium-speed rotation of the intermediate part, and low pressure during low-speed rotation of the end part. Thereby, joining quality can be improved further. Also in this case, it is possible to monitor whether or not the applied pressure is within a predetermined range at each pressurizing stage, and control to stop the joining operation when the applied pressure is not within the predetermined applied pressure range. .
[0053]
Depending on the workpiece, pressurization control may be performed so that the pressure is high during low-speed rotation and low pressure during high-speed rotation. Furthermore, the rotation speed is constant and control is performed so that only the pressure applied during welding is changed. May be.
[0054]
In the present embodiment described above, the workpiece is an aluminum alloy, but the present invention is not limited to this, and may be another metal workpiece or a synthetic resin workpiece.
[0055]
The following embodiments are possible for the present invention.
(1) A friction stir welding apparatus that detects whether or not the tip of the rotor is welded to an object to be joined using at least one of the rotation control means and the straight-ahead control means.
[0056]
For example, the rotation control means detects that a force greater than a predetermined force is required to rotate the rotor, or the straight-ahead control means detects that a force greater than a predetermined force is required to lift the rotor. In this case, it can be determined that the tip of the rotor and the workpiece are welded. In this way, welding detection can be reliably performed by the rotation control means or the straight-ahead control means.
[0057]
(2) The rotation control means detects whether or not the rotational speed of the rotor is within a predetermined rotational speed range during the joining operation of pressing the rotating rotor tip against the object to be joined. A friction stir welding apparatus that stops a joining operation when it is determined that the rotational speed is not within the range.
[0058]
The control of the friction stir welding apparatus only determines whether or not the rotational speed is within a predetermined range during the joining operation. When the rotational speed is not within the predetermined range, the joining operation is stopped. By monitoring the instantaneous value of the rotational speed during joining in this way, it is possible to reliably join at a predetermined rotational speed. Moreover, since it is only a judgment whether it is in the predetermined range, it is not necessary to perform complicated control and can be easily realized.
[0059]
For example, the rotation control means detects that a force greater than a predetermined force is required to rotate the rotor, or the straight-ahead control means detects that a force greater than a predetermined force is required to lift the rotor. In this case, it can be determined that the tip of the rotor and the workpiece are welded. In this way, welding detection can be reliably performed.
[0060]
(3) The rectilinear control means detects whether or not the applied pressure is within a predetermined applied pressure range during the joining operation of pressing the rotating rotor tip against the object to be joined. A friction stir welding apparatus characterized in that the joining operation is stopped when it is determined that there is not.
[0061]
The control of the friction stir welding apparatus only determines whether or not the applied pressure is within a predetermined range during the joining operation, and stops the joining operation when it is not within the predetermined range. Thus, by monitoring the instantaneous value of the applied pressure during the joining, the joining can be reliably performed with a predetermined applied pressure. Moreover, since it is only a judgment whether it is in the predetermined range, it is not necessary to perform complicated control, and realization is easy.
[0062]
The rotational speed control is determined based on whether or not the instantaneous value detected during the joining operation is within a predetermined range. That is, since complicated control like adaptive control is not performed, control is simple. Even in such a control only for determining whether or not the detected instantaneous value is within a predetermined range, the friction stir spot welding can realize a robust level that is practically free of problems.
[0063]
Similarly, the pressurization control is simple because it only determines whether or not the instantaneous value during the joining operation is within a predetermined pressure range. Even with such simple control, there is no problem in practical use.
[0064]
(4) The friction stir welding apparatus characterized in that the rotation control means changes the rotation speed of the rotor during the joining operation.
[0065]
Optimum joining can be achieved by changing the rotational speed of the rotor by the rotational speed control means during the joining operation in which the tip of the rotor is pressed against the object to be joined.
[0066]
(5) The friction stir welding apparatus characterized in that the linearly moving control means changes the pressure during the joining operation.
Optimum joining can be achieved by changing the applied pressure during the joining operation.
[0067]
【The invention's effect】
As described above, according to the present invention, since the rotation control means is provided, the rotation speed of the rotor can be variably controlled. As a result, spot bonding can be performed at an optimum rotational speed. Further, the linear control means can perform fine control of the pressing force, and can be joined with the optimum pressing force for spot joining.
[0068]
  According to the present invention, during the friction stir welding operation, the rotation control means changes the rotation speed of the rotor 22 so as to decrease or increase over time, or alternativelyTo drop once during the pressing periodThe speed change is performed stepwise or continuously, so that the friction stir welding of the workpieces to be joined can be performed under the optimum conditions, and the joint strength can be improved. Can be planned.
[0069]
According to the present invention, since the speed command value given from the linear control means to the linear motor 24, which is a linear drive source, has, for example, a triangular wave shape, the tip of the rotor 22 abruptly collides with a workpiece that is a workpiece. Therefore, it is possible to prevent the workpiece from vibrating and to achieve accurate friction stir welding.
[Brief description of the drawings]
FIG. 1 is a diagram showing a structure of a spot bonding gun 20 according to an embodiment of the present invention.
FIG. 2 is a first half of a flowchart of bonding control according to the present invention.
FIG. 3 is a second half of a flowchart of bonding control.
FIG. 4 is a timing chart of bonding control.
[Explanation of symbols]
10 Control device
11 Straight control section
12 Rotation control unit
20 Spot welding gun
22 Rotor
24 Linear motor
25 Motor for rotation

Claims (8)

The rotor rotating at high speed is moved straight in the direction of the rotation axis, the tip is pressed against the object to be joined, softened by the frictional heat between the tip and the contact part of the object to be joined, and stirred to In the friction stir welding apparatus for spot-joining the joint,
A rotation control means for changing and controlling the rotation speed of the rotor as time elapses during the friction stir welding operation;
A friction stir welding apparatus comprising: a linear movement control means for controlling a pressure during a friction stir welding operation by moving the rotor straight.   2. The friction stir welding apparatus according to claim 1, wherein the rotation control means changes the rotation speed so as to decrease with time during the friction stir welding operation.   2. The friction stir welding apparatus according to claim 1, wherein the rotation control means changes the rotational speed so as to increase with time during the friction stir welding operation. 2. The friction stir welding apparatus according to claim 1, wherein the rotation control means changes the rotation speed so as to drop once during the pressing period as time elapses during the friction stir welding operation.   The friction stir welding apparatus according to any one of claims 1 to 4, wherein the rotation control means changes the rotation speed stepwise or continuously. The straight-ahead control means
The speed command value having a shape having an inclined portion that increases the speed of the rotor with the lapse of time is derived at the initial stage of the friction stir welding operation. Friction stir welding device.   The friction stir welding apparatus according to claim 6, wherein the shape of the speed command value is a triangular wave shape.   The friction stir welding apparatus according to any one of claims 1 to 7, wherein the rotation speed is changed by the rotation control means in a state in which the pressurizing force is kept constant by the straight advance control means.

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