JP2004136305A - Method and equipment of friction stir welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of friction stir welding and equipment of the friction stir welding in which a rotating tool detects the center line and the width of a gap in line, and further easily detects a weld defect. <P>SOLUTION: The method of friction stir welding by which a joining is executed with friction heat input to the zone to be joined of works while the shoulder face of the rotating tool, which is pressed against and made contact to at least either the front or the rear of the joined face of the works, is slid and rotated on the zone to be joined of the works, is characterized in that at least one of the surface defect, the inner defect of the works, the position of a front part to be joined and a joint gap is detected on the basis of the rotational angular position and the detection signal of a sensor while rotating the detection sensor of the joined state of the works by following the rotational force of the rotating tool, and preferably the the detection sensor is rotating at a rotating speed lower than that of the rotating tool. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a friction stir welding method and a welding apparatus therefor, and more particularly to friction stir welding used for joining a single-skin or double-skin panel (double-sided hollow panel) when manufacturing a structure such as a vehicle, an aircraft, a ship, or a building. The present invention relates to a joining method and a joining device.
[0002]
[Prior art]
For example, Japanese Patent Application Publication No. 7-505090 (Patent Document 1) discloses a novel joining method of long materials as a solid-state joining method by friction stirring, and such a joining method is substantially more effective than a workpiece. By inserting a rotating tool made of a hard material into the joint of the workpiece and moving the rotating tool while rotating, the workpiece is joined by plastic flow due to frictional heat generated between the rotating tool and the workpiece. In the joining method, the joining member can be joined in the solid state while rotating and rotating the rotary tool while joining the softened solid part, so there is no thermal distortion and virtually infinite in the joining direction There is an advantage that solid phase bonding can be performed continuously in the longitudinal direction even for a long material. Furthermore, since solid-state welding is performed using plastic flow of metal due to frictional heat between the rotary tool and the joining member, joining can be performed without melting the joining portion. Further, since the heating temperature is low, deformation after bonding is small. Furthermore, since the joint is not melted, there are many advantages such as fewer defects.
[0003]
Next, a rotary tool used for friction stir welding will be described. As disclosed in Patent Document 1 and JP-A-2000-33484 (Patent Document 2), rotary tools used for friction stir welding include a probe type rotary tool and a bobbin tool type rotary tool, and a probe type tool. As shown in FIG. 7A, 20 has a shoulder portion 21 and a pin shaft 22 provided on the shoulder portion 21. The shoulder portion 21 has a circular shoulder surface. Then, the rotating tool 20 is rotated from the surface of the joint line in a state where a plurality of mold members are abutted or fitted, and the pin shaft 22 is caused to enter a hole (not shown) provided in the joint line of the workpiece. The frictional heat is imparted to the workpiece by the circular shoulder surface which rotates and slides on the joining line of the plurality of mold members, and the area around the probe 22 plastically fluidizes, and in this state, the rotary tool 20 is moved along the joining line. As a result, the two materials are stirred and kneaded while receiving pressure along the joining line while being plastically fluidized around the joining line, and moved to the rear side of the probe. As a result, the plastically flowed material loses frictional heat on the rear side and rapidly cools and solidifies, so that both panel plates are joined together in a state where the materials are mixed together and are completely integrated.
[0004]
The rotating tool 20 rotates at a high speed while the pin shaft 22 receives strong resistance in the forward direction. However, since the aluminum plate, the double skin type material and the like are formed by molding, the longer the tool, the lower its linearity. When this is matched, a gap is created.
For this reason, the friction stir welding is performed with the gaps made as small as possible by pressing the butted workpieces on the support plate of the workpieces.
Further, the position of the rotary tool 20 is controlled so that the rotary tool 20 tracks the center of the gap. However, a deviation of the pin shaft 22 of the rotary tool 20 from the center of the gap is inevitable. This is one of the major causes of the failure, and the above-mentioned deviation of the center of the rotary tool is also related to the allowable limit of the gap.
On the other hand, in the case of a welded workpiece by friction stir welding, if there is a defective welding portion, this portion becomes a weak point, a crack is formed from this portion, and this crack may grow and lead to a joint failure of the workpiece. For this reason, a repair operation is performed in which an inspection such as an ultrasonic flaw detection and a visual inspection is performed on the entire joint portion of the work to identify a defective joint portion and repair the defective joint portion.
[0005]
Such poor bonding is likely to cause internal defects and surface defects, for example, when the gap exceeds the allowable value and air is entrained by the stirring action of the rotating tool pin shaft.
[0006]
Therefore, in the friction stir welding, a defective portion is specified by inspecting the entire length of the welded portion and the defective portion is repaired. However, not only is it troublesome to specify the defective portion, but also such a repair work requires a long work. As a result, friction stir welding must be performed a plurality of times to repeatedly identify defective portions and repair them.
In order to solve this problem, in Japanese Patent No. 3274453 (Patent Document 3), a gap to be welded is constantly photographed by a CCD camera provided in front of a welding tool of a friction stir welding apparatus in a traveling direction, and friction stir welding is started. The forward distance from the point is constantly measured, the gap image captured by the CCD camera is image-processed, the width of the gap in the image is calculated, the calculated value is compared with a reference value, and the result is compared with the forward distance. We propose a joint failure detection method in friction stir welding, which is recorded in the memory together with the distance.
[0007]
[Patent Document 1] Japanese Patent Application Laid-Open No. Hei 7-505090 [Patent Document 2] JP-A-2000-33484
[Patent Document 3] Japanese Patent No. 3274453
[Problems to be solved by the invention]
However, in the prior art, since the CCD camera is fixed at a position in front of the joining tool in the traveling direction, only the gap (gap image) can be collected, and the gap can be measured from the gap image. The defective part cannot be specified.
That is, in the prior art, the calculated value of the gap width in the image is compared with a reference value, and the result is recorded in a memory together with the advance distance, so that the gap abnormality and the position of the entire joint can be grasped. Thus, it is possible to easily identify a joint failure in the subsequent repair work.
Therefore, in such a technique, the joining failure is predicted from the gap abnormality, and it is not intended to grasp whether or not the joining failure has actually occurred. It is not to grasp the joint failure inline.
The present invention has been made in view of the problems of the related art, and provides a friction stir welding method and a rotating stir welding method in which a rotary tool can not only detect a center line and a gap width of the gap in-line, but also easily detect a joining failure in-line. Is to do.
[0009]
[Means for Solving the Problems]
In order to solve this problem, the present invention presses against at least one of the front and back surfaces of the work joining surface, and slides and rotates the shoulder surface of the rotating tool to be brought into contact with the work joining portion while friction is applied to the work joining portion. In the friction stir welding method of joining by heat input,
While rotating the workpiece joining state detection sensor around the tool by following the rotational force of the rotating tool, the surface defect, internal defect, forward joining scheduled line position and joining of the workpiece based on the rotation angle position and the detection signal of the sensor. It is characterized in that at least one of the gaps is detected.
Incidentally, the workpiece bonding state detection sensor may be an eddy current sensor described in the embodiment described later.
[0010]
According to this invention, while rotating the work joining state detection sensor around the tool, based on the rotation angle position of the sensor and the detection signal, the surface defect of the work, the internal defect, the position of the expected joining line (groove position) and Since the joining gap (groove gap) can be detected in-line, it is easy to control the position of the rotating tool so that the rotating tool tracks the center of the gap. It can also be set by adding measures such as narrowing.
For example, before the main joining, the workpiece joining state detection sensor is rotated around the tool while following the rotational force of the rotary tool, and based on the rotation angle position and the detection signal of the sensor, the workpiece front joining scheduled line position (groove) Position) and the joining gap (groove width) are detected and stored in the storage device. Based on the storage results, the rotating tool is taught by the control device so that the rotating tool tracks the center of the gap. In addition, when the gap width is the gap allowable limit abnormality, the main joining can be performed after the gap is narrowed by a vice or the like.
[0011]
Further, while rotating the workpiece joining state detection sensor around the tool at the time of the final joining, the position of the scheduled joining line in front of the workpiece (groove position) and the joining gap (groove width) are detected based on the rotation angle position of the sensor and the detection signal. While performing the main joining based on the feed direction and feed speed that were taught while detecting with the circuit,
At this time, by detecting at least one of the surface defect and the internal defect of the work immediately after the joining, the joining failure can be grasped in-line, and various factors at the time of the joining failure can be grasped on the spot, and the rotational speed and the tool Adjustment of pressing force etc. can be done in-line.
[0012]
Although the rotating tool rotates at 400 rpm or more, the detection cycle of the sensor is not so necessary, and noise is easily generated in the sensor. Therefore, it is preferable that the detection sensor performs the rotational scanning while reducing the rotational speed of the rotary tool.
[0013]
In addition, in the case of a friction stir welding method in a so-called bobbin tool, a welding is performed by applying a pressing force via a pressing shoulder from the front side and the back side of the work joining section, respectively, and applying frictional heat to the joining section. At least one of a surface defect, an internal defect, a groove position, and a groove gap of the work by rotating a pair of work bonding state detection sensors that receive respective rotational forces of the front side shoulder and the back side shoulder via the work and face each other. 1 should be detected.
[0014]
According to this invention, since the transmission sensor and the reception sensor can be arranged face-to-face with the work interposed therebetween, for example, when the above-described configuration is employed, when an eddy current sensor is used as the sensor, when a current flows to the transmission sensor side Then, a secondary induced electromotive force acts on the base material (work) side, which further generates an induced electromotive force of the receiving sensor. Therefore, if there is a defect on the surface or inside of the base material, the induced electromotive force is disturbed, so that the surface and internal defects of the base material can be accurately detected based on the unstable signal.
[0015]
The invention according to claim 5 and subsequent claims is an invention relating to an apparatus for effectively carrying out the invention, wherein a workpiece joining state detection sensor which rotates concentrically with a tool by receiving a rotation force of the rotary tool, and a rotational angle position of the sensor And a detection circuit for detecting at least one of a surface defect, an internal defect, a scheduled forward joining line position and a joining gap of the work in response to the detection signal. In this case, the surface state detection sensor and the rotary tool are preferably connected via a speed reduction mechanism.
[0016]
Further, in an apparatus using a bobbin tool, a pair of work joining state detection sensors which receive respective rotational forces of the front side shoulder and the back side shoulder are arranged to face each other via a work, and the pair of sensors are synchronously rotated. It is preferable that a connecting mechanism to be provided is provided on the outer peripheral side of each shoulder.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail using embodiments shown in the drawings. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples.
FIG. 1 shows a schematic configuration of a friction stir welding apparatus according to a first embodiment of the present invention, in which a welding defect can be detected in an in-process, and a groove position and a gap width located in a traveling direction can be detected. It is.
In the present embodiment, the surface state detection sensor 30 is connected to a vertical axis along the axis of the rotary tool 20 via a connecting member 34 fixed to the outer peripheral surface of the probe type rotary tool 20 having the shoulder portion 21 and the pin shaft 22. Installed facing.
Since the surface state detecting sensor 30 integrally and cooperatively rotates in synchronization with the rotation of the rotary tool 20, the surface state of the base material 1 joint around the rotary tool 20 can be scanned.
At this time, the detection circuit 40 which takes in the signal of the surface state detection sensor 30 also takes in the signal of the tool rotation angle sensor 42 from the drive mechanism 41 including the motor for driving the rotary tool 20 and joins the rotating tool 20 in the joining direction (groove). When scanning the periphery of the position K), the groove position K and the gap G can be detected together with the signal of the rotation angle sensor 42.
[0018]
That is, when the surface state detection sensor 30 passes through the groove position K, the surface of the base material 1 becomes discontinuous, so that the detection signal of the output of FIG.
The groove position K can be known from the detected signal, the tool rotation angle from the rotation angle sensor 42, and the tool feed speed detection signal.
Since the width g of the detection signal shown in FIG. 5A is correlated with the gap width G of the groove shown in FIG. 1B, the width g of the groove gap is calculated based on the signal width g. Can be estimated.
When the surface condition detection sensor 30 scans the surface of the joint P immediately after the joining of the workpiece 1 on the rear side in the traveling direction of the rotary tool 20, if there is a defect S on the joint surface of the joint P in FIG. Thus, the detection signal is obtained, and the occurrence of the defect S can be detected.
[0019]
FIG. 2 shows a modified example of the embodiment of FIG. 1, in which a rotation reduction mechanism 25 is attached to the outer periphery of the tool 20 concentrically with the rotation tool 20, and the rotation force of the tool is greatly reduced. In addition, FIG. 3 is a perspective view of FIG.
Although the rotary tool 20 rotates at 400 rpm or more, the detection cycle of the surface state detection sensor 30 is not so necessary, and noise is easily generated in the surface state detection sensor 30. Therefore, the rotation speed reduction mechanism 25 is directly attached to the rotary tool 20, and the surface state detection sensor 30 is decelerated to perform rotation scanning.
The reduction mechanism 25 divides the middle of the body of the rotary tool 20 into two parts, attaches a shaft gear 26 to the center axis thereof, engages the plurality of reduction gears 27 with the shaft gear 26, and the surface state detection sensor 30 The ring-shaped connection frame 28 attached to the outer periphery is meshed with the sun gear 28a of the inner peripheral teeth.
The ring-shaped connecting frame 28 is rotatably engaged with the outer periphery of the flat disk portion 29a of the fixed cover 29, and further, the inner peripheral end of the flat disk portion 29a of the fixed cover 29 has a cylindrical portion of the fixed cover 29. 29b is suspended upward and fixed to the rotary tool 20.
[0020]
According to this embodiment, since the surface state detection sensor 30 and the rotary tool 20 are connected via the speed reduction mechanism 25, the surface state detection sensor 30 is decelerated with respect to the rotation speed of the rotary tool 20. It can be rotated in a state where As a result, the rotary tool 20 rotates at 400 rpm or more. However, the rotating tool 20 is decelerated in accordance with the detection cycle of the surface state detection sensor 30, so that the surface state detection sensor 30 is rotated and scanned in an optimal cycle without generating noise. be able to.
[0021]
FIG. 6 is an overall schematic block diagram showing a control system of the present invention incorporating such a detection mechanism.
For example, the control method according to the present embodiment is configured such that the rotation angle of the surface state detection sensor 30 is adjusted while rotating the surface state detection sensor 30 of the workpiece connection around the tool by following the rotational force of the rotary tool 20 before the main bonding. Based on the position and the detection signal, the workpiece pre-joining line position (groove position K) and the joining gap (groove width G) are detected by the detection circuit 40 and preliminarily traveled based on a predetermined feeding direction and stored. After storing in the device 44, the control device 43 corrects the feed speed and the feed direction of the rotary tool 20 based on the storage result from the storage device 44 so that the rotary tool 20 tracks the center of the gap width G. In addition, the teaching is performed, and when the gap width G is in the gap allowable limit abnormality, the gap width G is reduced by a vice or the like.
[0022]
At the time of the main joining, the workpiece front joining scheduled line position (groove position K) and the workpiece front joining position are determined based on the rotation angle positions and the detection signals of the two sensors 30 and 42 while rotating the workpiece state surface detection sensor 30 around the tool 20. While the joining circuit (groove width G) is detected by the detection circuit 40, the main joining is performed based on the feed direction and the feed speed taught by the control device 43.
The present joint at the time of each of the surface state detecting sensor 30 by the rotational angular position and the detected signal of the two sensors 30, 42 has passed the junction of the right after joining workpieces, surface defects defect S ₁ and internal defects S ₂ Is detected in-line, and various factors at the time of the joint failure are analyzed by the control device 43, and the feed direction, the feed speed, the rotational speed, and the adjustment of the pressing force of the tool are fed back. Main joining operation can be performed while controlling.
[0023]
FIG. 4 shows another embodiment of the bobbin tool for detecting the surface and internal defects of the base material, the groove position and the groove gap.
In the case of the bobbin tool, as shown by reference numeral 10 in FIG. 7B, a pair of shoulders 10A and 10B spaced from each other so as to sandwich the front and back surfaces of the workpiece to be joined are provided, and A pin shaft 11 is provided between the pair of shoulders 10A and 10B.
In addition to the bobbin tool 10, a pair of upper and lower shoulders 10A and 10B are fixed by 11 (Patent Document 1), and a pin shaft 11 of a lower shoulder penetrates through the upper shoulder. A friction stir welding apparatus using a bobbin tool with a variable pressing distance between shoulders (Patent Document 3) has also been proposed.
[0024]
In many of such tools, the lower shoulder 10B and the upper shoulder 10A rotate in synchronization with each other. For this reason, a pair of eddy current sensors are provided via connecting members at positions facing each other via the work between the shoulders 10A and 10B. By attaching 31 (reception side) and 32 (transmission side), the eddy current sensors 31 and 32 rotate synchronously facing each other.
[0025]
The principle of the eddy current sensors 31 and 32 will be described with reference to FIG. 4C. When an electric current is supplied to the transmitting sensor 31, the secondary induced electromotive force acts on the base material (work) side. Further, an induced electromotive force of the receiving sensor 32 is generated. Therefore, if there is a defect on the surface or inside of the joining portion of the base material (work) 1, the induced electromotive force is disturbed, and the surface and internal defects of the base material 1 can be detected based on this unstable signal.
In this case, the transmission-side sensor 31 and the reception-side sensor 32 may be provided on any of the lower and upper shoulders 10A and 10B. When the pressing force of the shoulder 10A is smaller than the pressing force of the back (lower) shoulder 10B, the back shoulder 10B has a function of inputting heat and the front shoulder 10A has a function of copying, and the joining surface on the front surface side of the work 1 is used. Is flat, the noise generation is reduced by setting the flat surface side to the receiving side.
Of course, also in this embodiment, a rotation reduction mechanism is attached to each of the pair of shoulders 10A and 10B spaced apart so as to sandwich both the front and back surfaces of the workpiece to be joined, and the rotation force of the tool is greatly reduced, and the rotation of each sensor is performed. It is good to be configured to apply force.
[0026]
【The invention's effect】
As described above, according to the present invention, while rotating the work joining state detection sensor around the tool, based on the rotation angle position of the sensor and the detection signal, the surface defect of the work, the internal defect, and the position of the scheduled forward joining line (opening position). Position) and the joint gap (groove gap) can be detected in-line, so that the position of the rotating tool can be easily controlled so that the rotating tool tracks the center of the gap. In such a case, it can be set by adding a device such as narrowing the gap.
At this time, by detecting at least one of the surface defect and the internal defect of the work immediately after the joining, the joining failure can be grasped in-line, and various factors at the time of the joining failure can be grasped on the spot, and the rotational speed and the tool Adjustment of pressing force etc. can be done in-line.
[0027]
In addition, since the detection sensor performs the rotational scanning while decelerating the rotational speed of the rotary tool, it is possible to perform scanning in accordance with the detection cycle of the sensor regardless of the rotational force of the rotary tool.
[0028]
In the case of a friction stir welding method using a so-called bobbin tool, a pair of work joining state detection sensors receiving respective rotational forces of the front side shoulder and the back side shoulder face each other via the work and are rotated synchronously to perform surface defect of the work. Preferably, at least one of an internal defect, a groove position and a groove gap is detected.
[0029]
According to this invention, since the transmission sensor and the reception sensor can be arranged face-to-face with the work interposed therebetween, for example, when the above-described configuration is employed, when an eddy current sensor is used as the sensor, when a current flows to the transmission sensor side Then, a secondary induced electromotive force acts on the base material (work) side, which further generates an induced electromotive force of the receiving sensor. Therefore, if there is a defect on the surface or inside of the base material, the induced electromotive force is disturbed, so that the surface and internal defects of the base material can be accurately detected based on the unstable signal.
[Brief description of the drawings]
FIG. 1 shows a schematic configuration of a friction stir welding apparatus according to a first embodiment of the present invention. In the in-process, a welding defect can be detected, and a groove position and a gap width located in a traveling direction can be detected. Things. In the figure, (A) is a front view and (B) is a perspective view.
FIG. 2 is a schematic front view showing a modified example of the embodiment of FIG. 1, in which a rotation reduction mechanism is attached to the outer periphery of the tool concentrically with the rotary tool, and the rotational force of the tool is greatly reduced; It applies a circling force.
FIG. 3 is a perspective view of FIG. 2;
FIG. 4 shows a schematic configuration of a friction stir welding apparatus according to another embodiment for detecting the surface and internal defects of a base material, a groove position and a groove gap in a bobbin tool, wherein (A) is a front view, and (B) is a front view; () Is a perspective view, and (C) is a schematic diagram showing a measurement principle.
5A and 5B are graphs showing detection signals of a sensor, wherein FIG. 5A is for detecting a groove position and a gap, and FIG. 5B is for detecting a surface defect.
FIG. 6 is an overall schematic block diagram of a control system of the present invention incorporating the detection mechanism of each embodiment.
FIG. 7 is a basic configuration diagram of a probe tool and a bobbin tool of friction stir welding according to the related art.
[Explanation of symbols]
1 Base Material 10A, 10B Bobbin Tool 20 Rotary Tool 25 Rotation Reduction Mechanism 30 Surface Condition Detection Sensor 34 Connector 40 Detection Circuit 43 Control Device 44 Storage Device

Claims (10)

A friction stir welding method in which welding is performed by frictional heat input to the work joint while the shoulder surface of the rotating tool that is pressed against at least one of the front and back surfaces of the work joint is slid and rotated on the work joint. ,
While rotating the workpiece joining state detection sensor around the tool by following the rotational force of the rotating tool, the surface defect, internal defect, forward joining scheduled line position and joining of the workpiece based on the rotation angle position and the detection signal of the sensor. A friction stir welding method comprising detecting at least one of the gaps. 2. The friction stir welding method according to claim 1, wherein the detection sensor rotates at a reduced speed with respect to a rotation speed of the rotary tool. The friction stir welding method according to claim 1 or 2, wherein welding is performed by applying a pressing force from a front side and a back side of the work bonding part via a pressing shoulder, respectively, and performing frictional heat input to the bonding part. A pair of work joining state detection sensors receiving respective rotational forces of the front side shoulder and the back side shoulder face each other via the work and are rotated synchronously so that at least the surface defect of the work, the internal defect, the planned front joining line position and the joining gap. 1. A friction stir welding method, wherein 4. The friction stir welding method according to claim 1, wherein the detection sensor is an eddy current sensor when the workpiece is a conductive material. At least one of the front and back surfaces of the work joining surface is pressed against, in a friction stir welding device having a rotating tool to be contacted,
A workpiece joining state detection sensor that rotates concentrically with the tool by receiving the rotational force of the rotary tool, and receives a rotational angle position and a detection signal of the sensor to detect a surface defect, an internal defect, a forward joining scheduled line position, and a workpiece of the workpiece. A friction stir welding apparatus comprising a detection circuit for detecting at least one of the gaps. The friction stir welding apparatus according to claim 5, wherein the surface state detection sensor and the rotary tool are connected via a speed reduction mechanism. 7. The friction stir welding apparatus according to claim 5, wherein pressing shoulders are respectively arranged from a front surface side and a back surface side of the work joining portion.
A pair of work joining state detection sensors that receive the respective rotational forces of the front side shoulder and the back side shoulder are disposed facing each other via a work, and a coupling mechanism that synchronously rotates the pair of sensors is provided on each shoulder outer peripheral side. A friction stir welding apparatus characterized by being provided. 8. The friction stir welding apparatus according to claim 5, wherein the detection sensor is an eddy current sensor when the work is a conductive material. The friction stir welding method according to claim 1 or 2,
Before the main joining, the workpiece joining state detection sensor is rotated around the tool by following the rotational force of the rotary tool, and based on the rotation angle position and the detection signal of the sensor, the workpiece front joining scheduled line position and the joining gap are determined. A friction stir welding method, wherein the main welding is performed after detecting at least one. At the time of the main joining, the workpiece joining state detection sensor is rotated around the tool, and at least one of a surface defect and an internal defect of the workpiece immediately after joining is detected based on a rotation angle position of the sensor and a detection signal. The friction stir welding method according to claim 9, wherein

Images