JP3546043B2 - Friction stir welding method and apparatus - Google Patents

Description

【００３３】
図６において、参照符４１は、本件発明者の実験結果を示し、参照符４２は従来からの施工例である比較例１を示す。図６に示される実施例１によれば、ピン３６が被接合物２２に接触（ｔ２）してからショルダ部３８が被接合物２２に接触する（ｔ３）までのピン貫入時間Ｗ１を短縮することができるとともに、摩擦接合強度である引張せん断強度を比較例１と同じにできることが本件発明者によって確認された。すなわち本発明によればピン貫入時間Ｗ１を短くすることによって接合動作時間（Ｗ１＋Ｗ２）ならびに摩擦接合に係る施工時間（Ｗ０＋Ｗ１＋Ｗ２＋Ｗ３）を短縮することができるとともに、摩擦接合強度が充分に維持することができることが確認された。表１に示すように、本発明の実施例は、１回の接合動作時間は、比較例に比べて１．５秒短縮することが確認された。したがって連続して複数箇所にスポット接合が行われる場合には、接合箇所の増加とともに、施工時間をより短縮することができ、スポット接合に特に良好に用いることができる。
【００３４】
図７は、本発明の実施の他の形態の簡略化した側面図である。この実施の形態では、前述の図１〜図６に関連して前述した摩擦撹拌接合装置２４は、複数（たとえば６）軸の産業用ロボット１の手首２に連結され、この摩擦撹拌接合装置２４を、ロボット１によって、希望する接合位置にもたらし、その手首２の位置を一時的に固定したままで、前述の図１〜図７に関連して述べたように、摩擦撹拌接合動作を行う。このロボット１のアームおよび手首２の動作は、図３に示される入力手段３の操作によって教示し、この教示内容をメモリ４にストアしておき、そのメモリ４のストア内容を読出すことによって、再生動作することができる。
【００３５】
図８は、本発明の実施の他の形態の処理回路３３の動作を説明するためのフローチャートである。上述した摩擦攪拌接合装置２４は、ショルダ部３８が被接合物２２の最上部の表面に接触したことを検出し、回転子２１の回転速度および押圧力を変更したが、他の状態を検出して回転子２１の回転速度および押圧力を変更してもよく、被接合物が複数枚重ねられる場合、回転子２１が被接合物の境界付近を押圧したとき、回転速度および押圧力を変更してもよい。たとえば、重ねられた２枚の被接合物のうち、上板２２と下板２３の境界付近にピン３６が到達したときに回転子２１の回転速度および押圧力が変更される。
【００３６】
図８に示す本発明の実施の他の形態の処理回路３３の動作は、図５に示す動作と類似しており、同様のステップについては、説明を省略する。図８のステップｂ１では、休止位置の状態から回転子２１が回転するとともに、被接合物に向けて直進移動し、ステップｂ２〜ステップｂ３では、図５のステップａ１〜ステップａ３と同一の動作が行われる。ステップｂ４では、直進駆動手段２９によって回転子２１がさらに直進移動され、上板２２の表面からピン３６の先端面までの距離である押込量Ｌが上板２２の板厚相当の距離Ｌｓを超える値であるか（Ｌ＞Ｌｓ）が判断される。押込量Ｌは、ステップｂ２でピン３６が上板２２の表面に接触したと判断されたときから、回転子２１の移動量を検出することによって得られる。この移動量は、たとえば測距センサを用いて、または直進駆動用モータの制御信号に基づいて求められる。このように押込量Ｌが上板２２の板厚相当の距離Ｌｓを超えたとステップｂ４で判断されると、次のステップｂ５では、ピン３６が上板２２を貫通し、ピン３６が下板２３に接触したことが判断される。
【００３７】
そこでステップｂ６では、回転子２１の回転速度および押圧力が図５のステップａ６と同様に前のステップｂ５までの回転速度Ｖ１および押圧力Ｐ１よりも低い回転速度Ｖ２および押圧力Ｐ２に変更して設定される。以降のステップｂ７〜ステップｂ８は、図５のステップａ７〜ステップａ８と同様に動作される。
【００３８】
上述したように、ツールの先端であるピン３６が上板２２と下板２３との境界付近に到達したときに回転子２１の回転速度および押圧力を変更しても図５に示す動作と同様に、施工時間を短縮することができるとともに、接合された被接合物の引張せん断強度が、充分に維持される。
【００３９】
前述の実施の形態では、検出手段３４は回転駆動用モータ３１の負荷電流を検出し、こうして検出された負荷電流が、図４（２）に示されるように出力トルクＴｐ，Ｔｓにそれぞれ対応する電流値によって、図５のステップａ２，ａ４でレベル弁別するように構成されたけれども、本発明の実施の他の形態では、検出手段３４によって検出される負荷電流が電流の時間変化率が、時刻ｔ２の前後および時刻ｔ３の前後で変化することに基づいて、予め定める各時間変化率以上であるかどうかを判断してレベル弁別するように構成してもよい。本発明の実施のさらに他の形態では、前述の検出手段３４に代えて、回転子２１の直進駆動手段２９による移動量を移動量検出手段７によって検出し、時刻ｔ２，ｔ３の各状態を検出するようにしてもよい。移動量検出手段７は、たとえば直進駆動用モータ３２の移動量を表す信号を検出し、移動量を判断してもよい。
【００４０】
さらに本発明の実施の他の形態では検出手段３４に代えて、回転子２１と被接合物２２，２３とをテレビカメラ８によって撮像して検出し、その画像処理によって、回転子２１と被接合物２２，２３との時刻ｔ２，ｔ３の各状態を検出するようにしてもよい。さらに本発明の実施の他の形態では、検出手段３４に代えて、タイマである時間計測手段９が設けられ、これによって回転子２１の直進駆動手段２９による時刻ｔ１からの各時間経過を計測し、時刻ｔ２，ｔ３の各状態を検出するようにしてもよい。
【００４１】
また本発明の実施の形態では、回転子２１の回転速度および押圧力を２段階に変化させたが、多段階たとえば３段階に変化させてもよい。第１段階としてショルダ部３８が被接合物２２に当接するまで、回転子２１の条件として高回転速度でかつ高押圧力に設定され、第２段階としてショルダ部３８が被接合物２２に当接したときに、被接合物２２への進行を一次停止した状態で高回転速度で回転子２１が回転し、予め定められる時間が経過した後第３段階に進み、第３段階として第１および第２段階よりも回転子２１の条件として低回転速度でかつ低押圧力に設定してもよい。第２段階でショルダ部３８が被接合物２２に当接した状態で進行せずに回転することによって摩擦熱による軟化部分を増加させてより良好な攪拌接合を行うことができる。
【００４２】
【発明の効果】
本発明によれば、回転子と被接合物との押圧接触中に、押圧力、したがって移動速度を変化させ、摩擦撹拌接合動作が進行するにつれて、回転子と被接合物との押圧力を低くするようにしたので、摩擦撹拌接合に必要な時間を短縮し、迅速な摩擦撹拌接合を行うことができるようになる。
また本発明によれば、第１の状態では、回転子の回転速度を高くし、または押圧力を高くして、短時間に摩擦熱を発生して、被接合物の部分的な軟化を促進する。次に、第２の状態では、被接合物の軟化部分の撹拌のために最適な回転速度となるように、または最適な押圧力となるように、これらの回転速度または押圧力のいずれか少なくとも一方を低下する。これによって回転速度または押圧力を変化しない場合に比べて、摩擦接合強度を維持したうえで、ピン貫入時間を短縮することができる。
また本発明によれば、最上部の被接合物の表面または、重ねられた被接合物の境界付近を回転子が押圧接触したときに、回転速度または押圧力を変化させる。これによって回転子の接触状態に応じて、最適な回転速度および押圧力を調整することができ、摩擦接合に必要な時間を短縮するとともに接合される被接合物の品質を維持または向上させることができる。
また本発明によれば、上述するように１つの箇所の接合に必要な時間を短縮することができるので、スポット接合によって複数箇所を連続して順に接合する場合には、連続して接合する箇所が増加すればするほど、作業時間を短縮することができる。
また本発明によれば、直進駆動手段によって、回転子と被接合物との押圧接触中に、押圧力を変化させ、摩擦撹拌接合動作が進行するにつれて、回転子と被接合物との押圧力を低くするようにしたので、摩擦撹拌接合に必要な時間を短縮し、迅速な摩擦撹拌接合を行うことができる。
また本発明によれば、第１の状態では、回転駆動手段によって回転子の回転速度を高くし、または直進駆動手段によって押圧力を高くして、短時間に摩擦熱を発生して、被接合物の部分的な軟化を促進する。次に、第２の状態では、被接合物の軟化部分の撹拌のために最適な回転速度となるように、または最適な押圧力となるように、回転駆動手段または直進駆動手段によって、これらの回転速度または押圧力のいずれか少なくとも一方を低下する。これによって回転速度または押圧力を変化しない場合に比べて、摩擦接合強度を維持したうえで、ピン貫入時間を短縮することができる。
【００４３】
また本発明によれば、検出手段によって回転駆動用モータの負荷電流、したがって出力トルクの値、その時間変化率を検出してもよく、テレビカメラによって回転子と被接合物とを撮像して画像処理を行ってもよく、さらにまたタイマなどの時間計測手段によって回転子の直進移動量を検出してもよい。このような検出手段を用いることで、回転速度および押圧力の少なくともいずれか一方の変化を、自動的に行うことかできるようになる。これによって被接合物の材質、板厚などの変化に応じて手動で回転速度および押圧力を切換える必要がない。
また本発明によれば、複数枚の被接合物が重ねられた場合には、最上部の被接合物の表面または、重ねられた被接合物の境界付近を回転子が押圧接触したときに、回転速度または押圧力を変化させる。これによって回転子の接触状態に応じて、最適な回転速度および押圧力を調整することができ、摩擦接合に必要な時間を短縮するとともに接合される被接合物の品質を維持または向上させることができる。
また本発明によれば、上述するように１つの箇所の接合に必要な時間を短縮することができるので、スポット接合によって複数箇所を連続して順に接合する場合には、連続して接合する箇所が増加すればするほど、作業時間を短縮することができる。したがって本発明は、特にスポット接合に良好に用いることができる。
【図面の簡単な説明】
【図１】本発明の実施の一形態の摩擦撹拌接合の状態を示す簡略化した断面図である。
【図２】本発明の実施の一形態の摩擦撹拌接合装置２４の簡略化した断面図である。
【図３】図２に示される摩擦撹拌接合装置２４の電気的構成を示すブロック図である。
【図４】図１〜図３に示される摩擦撹拌接合装置２４の動作を説明するためのタイムミングチャートである。
【図５】図３に示される処理回路３３の動作を説明するためのフローチャートである。
【図６】本件発明者の実験結果を示すグラフである。
【図７】本発明の実施の他の形態の簡略化した側面図である。
【図８】本発明の実施の他の形態の処理回路３３の動作を説明するためのフローチャートである。
【符号の説明】
１ 産業用ロボット
２ 手首
３ 入力手段
４ メモリ
７ 移動量検出手段
８ テレビカメラ
９ 時間計測手段
２１ 回転子
２２，２３ 被接合物
２４ 摩擦撹拌接合装置
２５ 定盤
２６ 装置本体
２７ 回転駆動手段
２８ 軸線
２９ 直進駆動手段
３１ 回転駆動用モータ
３３ 処理回路
３４ 検出手段
３６ ピン
３７ 先端部
３８ ショルダ部
ｔ１〜ｔ５ 時刻[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a friction stir welding apparatus that performs, for example, spot welding on a workpiece by friction stir welding.
[0002]
[Prior art]
In the prior art, while maintaining the rotation speed of the rotor and the moving speed moving toward the workpiece, set at a low predetermined value suitable for stirring the softened portion by frictional heat of the workpiece, Always work. Therefore, the period from the start to the end of the friction welding becomes undesirably long.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a friction stir welding method and apparatus capable of shortening the time required for friction stir welding.
[0004]
[Means for Solving the Problems]
The present invention presses a rotor rotating at a high speed and a workpiece to each other, and partially softens the workpiece by frictional heat between the rotor and the workpiece, and agitates the softened portion to perform welding. In the friction stir welding method of joining objects,
The state of friction stir between the rotor and the workpiece is detected, and based on this detection result, as the friction stir operation proceeds,, TimesThis is a friction stir welding method characterized by lowering the pressing force between the trochanter and the workpiece.
According to the present invention, the pressing force can be changed during the pressing contact between the rotor and the article to be joined, and the time required for friction joining of the article to be joined, such as spot joining, can be reduced. The pressing force and further the speed of the linear movement of the rotor to the workpiece are increased due to the frictional heat between the rotor and the workpiece, and the workpiece is partially softened in a short time. , The pressing force, and the speed of the rectilinear movement are reduced to an optimum value for stirring the softened portion. Both the rotation speed and the pressing force may be changed during the pressing contact. In another embodiment of the present invention, the rotor may not be provided with a pin.
[0005]
Also, the present inventionThe rotor, which has a shoulder portion and a pin protruding from the shoulder portion toward the object to be joined, is pressed against the object to be joined, and the object to be joined is pressed by frictional heat between the rotor and the object to be joined. In the friction stir welding method of partially softening, stirring the softened portion and welding the workpiece,
The friction stir state between the rotor and the workpiece is detected, and based on the detection result, the shoulder portion is pressed against the workpiece, compared to the state where only the pin is pressed against the workpiece. In the friction stir welding method, the rotating speed of the rotor is reduced or the pressing force between the rotor and the workpiece is reduced when the rotor is in the state.
According to the invention, the rotor has the shoulder portion and the pin, and in the first state where only the pin is in contact with the workpiece, the rotation speed of the rotor is increased or the pressing force is increased. As a result, frictional heat is generated in a short time to promote partial softening of the workpiece. Thus, in the second state in which the pin has entered the workpiece and the shoulder portion has contacted the workpiece, an optimal rotation speed is provided for stirring the softened portion of the workpiece, or an optimal pressing force. At least one of the rotation speed and the pressing force is reduced. Thereby, compared with the case where the rotation speed or the pressing force is not changed, the construction time can be shortened while maintaining the frictional joining strength.
The pins of the rotor may be in the shape of a right cylinder or may be in the shape of a cylinder. The distal end portion having a shoulder portion to which the proximal end portion of the pin is connected may be, for example, a straight cylinder coaxial with the pin or an inverted truncated cone. Further, a guide hole is formed coaxially with the rotor, and a metal material is supplied to the guide hole and sent out from the tip of the pin. It is also possible to prevent formation of places.
[0006]
The present invention also provides a method in which a rotor rotating at a high speed and a workpiece are pressed against each other, and the workpiece is partially softened by frictional heat between the rotor and the workpiece, and the softened portion is agitated and stirred. In the friction stir welding method of joining the articles,
A plurality of workpieces are stacked, and it is detected that the rotor has pressed against the surface of the uppermost workpiece or the vicinity of the boundary of the superposed surfaces, and the friction stir operation is performed based on the detection result. The friction stir welding method is characterized in that the rotational speed of the rotor or the pressing force between the rotor and the object to be welded is reduced as the process proceeds.
According to the present invention, when a plurality of workpieces are stacked, when the rotor presses and contacts the surface of the uppermost workpiece or the vicinity of the boundary of the stacked workpieces, the rotation is performed. Change the speed or pressing force. This makes it possible to adjust the optimum rotation speed and pressing force according to the contact state of the rotor, thereby shortening the time required for friction welding and maintaining or improving the quality of the workpieces to be welded. it can.
[0007]
Further, the present invention is characterized in that the friction stir welding is spot welding..
[0008]
According to the present invention, as described above, it is possible to reduce the time required for joining one place, and when joining a plurality of places successively by spot joining, the places to be joined continuously are The greater the number, the shorter the work time. Therefore, the present invention can be favorably used especially for spot joining..
[0009]
Also, the present inventionFriction stir welding that presses the high-speed rotating rotor against the workpiece, partially softens the workpiece by frictional heat between the rotor and the workpiece, agitates the softened part, and welds the workpiece In the device,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
Detecting means for detecting a state in which the rotor is in pressure contact with the article to be welded,
Control means for reducing the pressing force of the linear drive means as the friction stir operation progresses based on the output in response to the output of the detection means.It is.
[0010]
According to the present invention, in response to the output of the detecting means, the pressing force between the rotor and the article to be joined is changed by the linear drive means during the press contact between the rotor and the article to be joined. It is possible to reduce the time required for friction joining of the object, for example, spot joining. First, the pressing force and the speed of the linear movement of the rotor to the workpiece are increased due to the frictional heat between the rotor and the workpiece, and the workpiece is partially softened in a short time. Thereafter, the pressing force and further the speed of the straight movement are reduced to an optimum value for stirring the softened portion. Both the rotation speed and the pressing force may be changed during the pressing contact. In another embodiment of the present invention, the rotor may not be provided with a pin.
[0011]
Also, the present invention provides a method for pressing a rotor that has a shoulder portion and a pin protruding from the shoulder portion toward a workpiece to rotate at a high speed against the workpiece, and generates frictional heat between the rotor and the workpiece. In a friction stir welding apparatus that partially softens the workpiece and agitates the softened portion to weld the workpiece,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
Detecting means for detecting a state in which the rotor is in pressure contact with the article to be welded,
In response to the output of the detection means, as the friction stir operation progresses based on the output, the rotation speed by the rotation drive means, or control means to reduce the pressing force by the linear drive means, the detection means,
A first state in which only the pin is in pressure contact with the workpiece;
Detecting the second state in which the shoulder portion is in pressure contact with the workpiece,
The control means is
The friction stir welding apparatus is characterized in that the rotation speed is reduced or the pressing force is reduced in the second state compared to the first state.
[0012]
According to the present invention, in the first state, the rotational speed of the rotor is increased by the rotational drive means, or the pressing force is increased by the linear drive means, and frictional heat is generated in a short time, and Promotes partial softening of Next, in the second state, the linear drive unit or the rotary drive unit is controlled so as to have an optimum rotation speed or an optimum pressing force for stirring the softened portion of the workpiece. And at least one of the rotation speed and the pressing force is reduced. Thereby, compared with the case where the rotation speed or the pressing force is not changed, the construction time can be shortened while maintaining the frictional joining strength.
[0013]
Further, in the present invention, the rotation driving means includes a rotation driving motor,
A detecting unit that detects a load current of the rotary drive motor;
In response to the output of the sensor, a level discriminating means for level discriminating whether the detected load current is equal to or greater than a predetermined current value, or whether a time rate of change is equal to or greater than a predetermined time rate of change,
In response to the output of the level discriminating means, when the detected load current is equal to or greater than a predetermined current value, or when the time rate of change is equal to or greater than a predetermined time rate of change, the state changes from the first state to the second state. And changing means..
[0014]
According to the present invention,A sensor detects a load current of the rotary drive motor, and thus an output torque, and a load current corresponding to the output torque is equal to or greater than a predetermined current value, or a time change rate of the load current is equal to or greater than a predetermined time change rate. Level discrimination by the level discriminating means, thereby detecting that the shoulder portion has come into contact with the workpiece, changing the rotation speed or the pressing force of the rotor by the changing means, and automatically performing friction stir welding. Can be performed quickly.
[0015]
Further, according to the present invention, the detecting means comprises:
(A) a first state and a second state,
By the amount of movement of the rotor by the linear drive means, or
A sensor that detects the image of the rotor and the workpiece by a television camera,
(B) changing means for changing from the first state to the second state in response to the output of the sensor.
Further, according to the present invention, the detecting means comprises:
Time measuring means for measuring the passage of time by means of the linear driving means of the rotor,
Changing means for changing from the first state to the second state in response to the output of the time measuring means.
[0016]
According to the present invention, the detecting means may also take an image of the joining state between the rotor and the article to be joined by a television camera and perform image processing on the joining state. May be detected as having contacted the object.
[0017]
Also, the present inventionFriction stir welding that presses the high-speed rotating rotor against the workpiece, partially softens the workpiece by frictional heat between the rotor and the workpiece, agitates the softened part, and welds the workpiece In the device,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
A plurality of workpieces are stacked, and a detecting means for detecting a state in which the rotor is in pressure contact with the surface of the uppermost workpiece or near the boundary of the stacked workpieces,
Control means for responding to the output of the detecting means and reducing the rotational speed of the rotary drive means or the pressing force of the linear drive means as the friction stir operation progresses based on the output. Device.
[0018]
According to the present invention, when a plurality of workpieces are stacked, when the rotor presses and contacts the surface of the uppermost workpiece or the vicinity of the boundary of the stacked workpieces, the rotation is performed. The rotation speed or the pressing force is changed by the driving means or the straight driving means. This makes it possible to adjust the optimum rotation speed and pressing force according to the contact state of the rotor, thereby shortening the time required for friction welding and maintaining or improving the quality of the workpieces to be welded. it can.
[0019]
Further, the present invention is characterized in that the friction stir welding is spot welding.
[0020]
According to the present invention, as described above, it is possible to reduce the time required for joining one place, and when joining a plurality of places successively by spot joining, the places to be joined continuously are The greater the number, the shorter the work time. Therefore, the present invention can be favorably used especially for spot joining.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a simplified sectional view showing a state of friction stir welding according to an embodiment of the present invention. The rotor 21 is driven to rotate, and the metal workpieces 22 and 23 superimposed on each other in the upper and lower directions in FIG. 1 are friction-stir-welded and spot-welded. The spot joining moves along the axis of the rotor 21 without traveling in a direction perpendicular to the axis of the rotor 21 to join the workpieces.
[0022]
FIG. 2 is a simplified cross-sectional view of the friction stir welding apparatus 24 according to one embodiment of the present invention. The objects 22 and 23 are mounted on the surface plate 25 and fixed. The apparatus main body 26 fixedly provided to the surface plate 25 is provided with a rotation driving means 27, and the rotation driving means 27 drives the rotor 21 around its vertical axis 28. The rotor 21 can be moved up and down in FIG. 2 along the axis 28 by the straight drive means 29.
[0023]
FIG. 3 is a block diagram showing an electrical configuration of the friction stir welding device 24 shown in FIG. The rotation drive unit 27 includes a rotation drive motor 31, and the straight drive unit 29 includes a straight drive motor 32. An output from a detecting means 34 for detecting a load current of the rotation driving motor 31 is given to a processing circuit 33 realized by a microcomputer or the like.
[0024]
Referring again to FIG. 1, rotor 21 includes a right columnar pin 36 protruding toward workpieces 22 and 23, and a distal end 37 at which the base end of pin 36 is integrally provided. Have. The pin 36 and the tip 37 have respective axes on the axis 28. The tip 37 has a right cylindrical shape. The lower end face of FIG. 1 facing the pin 36 of the distal end portion 37 forms a shoulder portion 38.
[0025]
FIG. 4 is a timing chart for explaining the operation of the friction stir welding apparatus 24 shown in FIGS. In the friction stir welding of the articles 22 and 23, before time t1 in FIG. 4, the vertical position of the rotor 21 is as shown in FIG. 4 (1). As shown in ()), the rotor 21 is above the workpieces 22 and 23. The load current detected by the detection means 34 of the rotation drive motor 31 is as shown in FIG. 4B and is a relatively low value. This load current corresponds to the output torque of the rotary drive motor 31. The rotation speed of the rotation drive motor 31, that is, the rotation speed of the rotor 21 is as shown in FIG. 4C, and the rotation is stopped at time t1. A pressing force shown in FIG. 4D is applied between the rotor 21 and the workpieces 22 and 23 by the straight driving means 29 including the straight driving motor 32.
[0026]
FIG. 5 is a flowchart for explaining the operation of the processing circuit 33 shown in FIG. At step a1 in FIG. 5, at time t1 in FIG. 4, rotation of the rotor 21 about its axis 28 by the rotation drive means 27 including the rotation drive motor 31 is performed at the rest position in FIG. Starting from the state, the rotation speed V1 is a relatively high value at this time. The rotor 21 is linearly moved toward the workpieces 22 and 23 by the linear drive means 29 and descends.
[0027]
In step a2 of FIG. 5, whether the load current of FIG. 4 (2) detected by the detecting means 34, that is, the output torque T of the rotary drive motor 31 exceeds a predetermined value Tp (T> Tp). Is determined. When the pin 36 of the rotor 21 contacts the surface of the workpiece 22 at the time t2 in FIG. 4 as shown in FIG. 1 (2), the output torque T corresponding to the load current of the rotation drive motor 31 becomes It exceeds the output torque Tp corresponding to the value of the predetermined load current. Thus, it is determined in step a3 that the pin 36 has come into contact with the surface of the uppermost workpiece 22. The period from time t1 to t2 is indicated by W0.
[0028]
The rotor 21 is further linearly moved by the linear drive means 29. In step a4, the output torque T corresponding to the load current of the rotary drive motor 31 detected by the detection means 34 corresponds to the predetermined load current. Is determined (T> Ts, where Ts> Tp). When the shoulder 38 of the rotor 21 comes into contact with the uppermost surface of the article 22 at time t3 in FIG. 4, the load current of the rotation drive motor 31 detected by the detecting means 34 becomes equal to the predetermined output torque Ts. Exceed the corresponding load current value. When this is determined in step a4, it is determined in next step a5 that the shoulder portion 38 has contacted the surface of the article 22. The period from time t2 to t3 is indicated by W1.
[0029]
Therefore, in step a6, after time t3, as shown in FIG. 4C, the rotational speed of the rotor 21 by the rotational drive motor 31 is generated by friction stirring between the rotor 21 and the workpieces 22, 23. The rotation speed is changed to V2 (where V1> V2) suitable for the portion softened by the generated frictional heat to be stirred and joined. The rectilinear driving motor 32 of the rectilinear driving means 29 is stopped or driven after time t3, and the pressing force P2 between the rotor 21 and the workpieces 22 and 23 is less than the pressing force P1 at times t2 to t3. An appropriate value is set (P1> P2).
[0030]
In step a7 of FIG. 5, when it is determined that the agitation execution time after time t3 reaches the predetermined value W2, at time t4, the straight drive motor 32 is rotated in the reverse direction. As shown in (1), the rotor 21 is lifted away from the workpieces 22, 23 as shown in FIG. 1 (5). When the rotor is pulled out, the rotor 21 rotates at the rotation speed of the previous step, that is, at the rotation transfer rate V2 suitable for joining. In this way, at time t5, when the rotor 21 reaches the same rest position as before time t1, in step a8, all the operations of the friction stir welding until time t5 over the periods W0, W1, W2, and W3 from time t1 are performed. To end.
[0031]
FIG. 6 is a graph showing experimental results of the present inventor. The conditions under which the experiment of FIG. 6 was performed are as shown in Table 1.
[0032]
[Table 1]

[0033]
In FIG. 6, reference numeral 41 indicates an experimental result of the present inventor, and reference numeral 42 indicates Comparative Example 1 which is a conventional construction example. According to the first embodiment shown in FIG. 6, the pin penetration time W1 from when the pin 36 contacts the article 22 (t2) to when the shoulder 38 contacts the article 22 (t3) is reduced. It was confirmed by the present inventors that the tensile shear strength, which is the friction joining strength, can be the same as that of Comparative Example 1. That is, according to the present invention, by shortening the pin penetration time W1, the joining operation time (W1 + W2) and the working time (W0 + W1 + W2 + W3) related to the friction joining can be shortened, and the friction joining strength can be sufficiently maintained. Was confirmed. As shown in Table 1, it was confirmed that in the example of the present invention, one joining operation time was reduced by 1.5 seconds as compared with the comparative example. Therefore, when spot joining is continuously performed at a plurality of locations, the number of joining locations can be increased, and the construction time can be further shortened.
[0034]
FIG. 7 is a simplified side view of another embodiment of the present invention. In this embodiment, the friction stir welding device 24 described above with reference to FIGS. 1 to 6 is connected to the wrist 2 of the industrial robot 1 having a plurality of (for example, six) axes, and the friction stir welding device 24 is Is brought to a desired joining position by the robot 1, and while the position of the wrist 2 is temporarily fixed, the friction stir welding operation is performed as described with reference to FIGS. The operation of the arm and the wrist 2 of the robot 1 is taught by operating the input means 3 shown in FIG. 3, the contents of the teaching are stored in the memory 4, and the stored contents of the memory 4 are read out. Playback operation can be performed.
[0035]
FIG. 8 is a flowchart for explaining the operation of the processing circuit 33 according to another embodiment of the present invention. The friction stir welding device 24 described above detects that the shoulder portion 38 has come into contact with the uppermost surface of the article 22 and changes the rotation speed and the pressing force of the rotor 21, but detects other states. The rotation speed and the pressing force of the rotor 21 may be changed, and when a plurality of objects are stacked, when the rotor 21 presses near the boundary of the object to be bonded, the rotation speed and the pressing force are changed. You may. For example, the rotation speed and the pressing force of the rotor 21 are changed when the pin 36 reaches the vicinity of the boundary between the upper plate 22 and the lower plate 23 among the two joined objects.
[0036]
The operation of the processing circuit 33 according to another embodiment of the present invention shown in FIG. 8 is similar to the operation shown in FIG. 5, and the description of the same steps will be omitted. In step b1 of FIG. 8, the rotor 21 rotates from the rest position and moves straight toward the workpiece. In steps b2 to b3, the same operations as those in steps a1 to a3 of FIG. Done. In step b4, the rotor 21 is further linearly moved by the linear drive means 29, and the pushing amount L, which is the distance from the surface of the upper plate 22 to the tip end surface of the pin 36, exceeds the distance Ls corresponding to the plate thickness of the upper plate 22. It is determined whether the value is a value (L> Ls). The pushing amount L is obtained by detecting the moving amount of the rotor 21 from when it is determined that the pin 36 has contacted the surface of the upper plate 22 in step b2. This movement amount is obtained, for example, using a distance measuring sensor or based on a control signal of a straight drive motor. When it is determined in step b4 that the pushing amount L exceeds the distance Ls corresponding to the plate thickness of the upper plate 22 in this way, in the next step b5, the pins 36 penetrate the upper plate 22 and the pins 36 It is determined that the contact has been made.
[0037]
Therefore, in step b6, the rotation speed and the pressing force of the rotor 21 are changed to the rotation speed V2 and the pressing force P2 lower than the rotation speed V1 and the pressing force P1 up to the previous step b5 as in step a6 of FIG. Is set. The subsequent steps b7 to b8 are operated in the same manner as steps a7 to a8 in FIG.
[0038]
As described above, even when the rotation speed and the pressing force of the rotor 21 are changed when the pin 36, which is the tip of the tool, reaches the vicinity of the boundary between the upper plate 22 and the lower plate 23, the operation is the same as that shown in FIG. In addition, the construction time can be reduced, and the tensile shear strength of the joined objects can be sufficiently maintained.
[0039]
In the above-described embodiment, the detecting means 34 detects the load current of the rotary drive motor 31, and the detected load currents correspond to the output torques Tp and Ts, respectively, as shown in FIG. Although the level is discriminated in steps a2 and a4 in FIG. 5 according to the current value, in another embodiment of the present invention, the load current detected by the detection means 34 is a time change rate of the current, Based on the change before and after t2 and before and after time t3, it may be configured to judge whether the rate of change is equal to or more than a predetermined time change rate and to perform level discrimination. In still another embodiment of the present invention, instead of the above-described detecting means 34, the moving amount of the rotor 21 by the linear driving means 29 is detected by the moving amount detecting means 7, and the states at times t2 and t3 are detected. You may make it. The movement amount detecting means 7 may determine a movement amount by detecting, for example, a signal indicating a movement amount of the straight drive motor 32.
[0040]
Further, in another embodiment of the present invention, the rotator 21 and the workpieces 22 and 23 are imaged and detected by the television camera 8 instead of the detection means 34, and the rotor 21 and the workpiece 21 are joined by image processing. Each state at times t2 and t3 with the objects 22 and 23 may be detected. Further, in another embodiment of the present invention, a time measuring means 9 which is a timer is provided in place of the detecting means 34, thereby measuring each elapsed time from the time t1 by the straight driving means 29 of the rotor 21. , The states at times t2 and t3 may be detected.
[0041]
Further, in the embodiment of the present invention, the rotation speed and the pressing force of the rotor 21 are changed in two stages, but may be changed in multiple stages, for example, three stages. As a first step, the condition of the rotor 21 is set to a high rotation speed and a high pressing force until the shoulder portion 38 comes into contact with the article 22. As a second step, the shoulder section 38 comes into contact with the article 22. Then, the rotor 21 rotates at a high rotation speed in a state where the advance to the article 22 is temporarily stopped, and proceeds to a third stage after a predetermined time elapses. The rotor 21 may be set to have a lower rotation speed and a lower pressing force than two stages. In the second stage, the shoulder portion 38 rotates without advancing while being in contact with the article 22, so that the softened portion due to frictional heat is increased, so that better stirring welding can be performed.
[0042]
【The invention's effect】
According to the present invention, during the pressure contact between the rotor and the workpiece,, PushChange pressure, and therefore movement speedAs the friction stir welding operation progressed, the pressing force between the rotor and the workpiece was reduced,The time required for friction stir welding can be reduced, and rapid friction stir welding can be performed.
Further, according to the present invention, in the first state, the rotational speed of the rotor is increased or the pressing force is increased to generate frictional heat in a short time, thereby promoting partial softening of the workpiece. I do. Next, in the second state, at least one of these rotation speeds or the pressing force is set so as to have the optimum rotation speed for stirring the softened portion of the article to be bonded or the optimum pressing force. Decrease one. As a result, the pin penetration time can be reduced while maintaining the frictional joining strength as compared with the case where the rotation speed or the pressing force is not changed.
Further, according to the present invention, the rotation speed or the pressing force is changed when the rotor presses and contacts the surface of the uppermost workpiece or the vicinity of the boundary of the stacked workpieces. This makes it possible to adjust the optimum rotation speed and pressing force according to the contact state of the rotor, thereby shortening the time required for friction welding and maintaining or improving the quality of the workpieces to be welded. it can.
Further, according to the present invention, as described above, it is possible to reduce the time required for joining one place, and when joining a plurality of places successively by spot joining, the places to be joined continuously , The working time can be shortened.
According to the invention, the pressing force is changed by the linear drive means during the pressing contact between the rotor and the workpiece, and as the friction stir welding operation proceeds, the pressing force between the rotor and the workpiece is increased. , The time required for friction stir welding can be shortened, and rapid friction stir welding can be performed.
Further, according to the present invention, in the first state, the rotational speed of the rotor is increased by the rotational driving means, or the pressing force is increased by the linear driving means to generate frictional heat in a short time, and Promotes partial softening of objects. Next, in the second state, these are rotated by a rotation driving unit or a straight driving unit so as to have an optimal rotation speed for stirring the softened portion of the article to be joined or an optimal pressing force. At least one of the rotation speed and the pressing force is reduced. As a result, the pin penetration time can be reduced while maintaining the frictional joining strength as compared with the case where the rotation speed or the pressing force is not changed.
[0043]
According to the present invention,Detection means detects the load current of the rotary drive motor, and thus the output torque value and its time rate of change.May beThe rotor and the workpiece are imaged by a TV camera and image processing is performed.May be, And also detects the amount of linear movement of the rotor by time measurement means such as a timer.Is also good. By using such detection means,At least one of the rotation speed and the pressing force can be automatically changed. This eliminates the need to manually switch the rotation speed and pressing force according to changes in the material, plate thickness, and the like of the workpiece.
Further, according to the present invention, when a plurality of workpieces are stacked, when the rotor is pressed against the surface of the uppermost workpiece or near the boundary of the stacked workpieces, Change the rotation speed or pressing force. This makes it possible to adjust the optimum rotation speed and pressing force according to the contact state of the rotor, thereby shortening the time required for friction welding and maintaining or improving the quality of the workpieces to be welded. it can.
Further, according to the present invention, as described above, it is possible to reduce the time required for joining one place, and when joining a plurality of places successively by spot joining, the places to be joined continuously , The working time can be shortened. Therefore, the present invention can be favorably used especially for spot joining.
[Brief description of the drawings]
FIG. 1 is a simplified cross-sectional view showing a state of friction stir welding according to an embodiment of the present invention.
FIG. 2 is a simplified cross-sectional view of a friction stir welding apparatus 24 according to one embodiment of the present invention.
FIG. 3 is a block diagram showing an electrical configuration of the friction stir welding apparatus 24 shown in FIG.
FIG. 4 is a timing chart for explaining the operation of the friction stir welding apparatus 24 shown in FIGS. 1 to 3;
FIG. 5 is a flowchart for explaining the operation of the processing circuit 33 shown in FIG. 3;
FIG. 6 is a graph showing experimental results of the present inventor.
FIG. 7 is a simplified side view of another embodiment of the present invention.
FIG. 8 is a flowchart illustrating an operation of a processing circuit 33 according to another embodiment of the present invention.
[Explanation of symbols]
1 industrial robots
2 wrist
3 Input means
4 memory
7 Moving amount detecting means
8 TV camera
9 Time measurement means
21 Rotor
22, 23 Workpiece
24 Friction stir welding equipment
25 surface plate
26 Main unit
27 Rotation drive means
28 axis
29 Straight driving means
31 Rotary drive motor
33 processing circuit
34 Detecting means
36 pins
37 Tip
38 Shoulder
t1 to t5 time

Claims (11)

The high-speed rotating rotor and the workpiece are pressed against each other, and the frictional heat between the rotor and the workpiece is used to partially soften the workpiece and agitate the softened portion to join the workpiece. In the friction stir welding method,
Detecting a friction stir state between the rotor and the object to be bonded, on the basis of the detection result, as the friction stir operation progresses, the pressing force of the rotating rotor and the object to be bonded, characterized by low Friction stir welding method. The rotor, which has a shoulder portion and a pin protruding from the shoulder portion toward the object to be joined, is pressed against the object to be joined, and the object to be joined is pressed by frictional heat between the rotor and the object to be joined. In the friction stir welding method of partially softening, stirring the softened portion and welding the workpiece,
The friction stir state between the rotor and the workpiece is detected, and based on the detection result, the shoulder portion is pressed against the workpiece, compared to the state where only the pin is pressed against the workpiece. A friction stir welding method, wherein the rotating speed of the rotor is reduced, or the pressing force between the rotor and the workpiece is reduced in a state where the rotor is in a state of being engaged . The high-speed rotating rotor and the workpiece are pressed against each other, and the frictional heat between the rotor and the workpiece is used to partially soften the workpiece and agitate the softened portion to join the workpiece. In the friction stir welding method,
A plurality of workpieces are stacked, and it is detected that the rotor has pressed against the surface of the uppermost workpiece or the vicinity of the boundary of the superposed surfaces, and the friction stir operation is performed based on the detection result. The rotational speed of the rotor or the pressing force between the rotor and the object to be welded is reduced as the process proceeds. The friction stir welding method according to any one of claims 1 to 3, wherein the friction stir welding is spot welding. Friction stir welding that presses the high-speed rotating rotor against the workpiece, partially softens the workpiece by frictional heat between the rotor and the workpiece, agitates the softened part, and welds the workpiece In the device,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
Detecting means for detecting a state in which the rotor is in pressure contact with the article to be welded,
A friction stir welding apparatus, comprising: a control unit that responds to the output of the detection unit and reduces the pressing force of the linear drive unit as the friction stir operation proceeds based on the output. The rotor, which has a shoulder portion and a pin protruding from the shoulder portion toward the object to be joined, is pressed against the object to be joined, and the object to be joined is pressed by frictional heat between the rotor and the object to be joined. In a friction stir welding apparatus that partially softens, stirs the softened portion and joins the workpiece,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
Detecting means for detecting a state in which the rotor is in pressure contact with the article to be welded,
In response to the output of the detection means, as the friction stir operation progresses based on the output, the rotation speed by the rotation drive means, or control means to reduce the pressing force by the linear drive means, the detection means,
A first state in which only the pin is in pressure contact with the workpiece;
Detecting the second state in which the shoulder portion is in pressure contact with the workpiece,
The control means is
A friction stir welding apparatus, wherein the rotation speed is reduced or the pressing force is reduced in a second state compared to a first state. The rotation driving means includes a rotation driving motor,
A detecting unit that detects a load current of the rotary drive motor;
In response to the output of the sensor, a level discriminating means for level discriminating whether the detected load current is equal to or greater than a predetermined current value, or whether a time rate of change is equal to or greater than a predetermined time rate of change,
In response to the output of the level discriminating means, when the detected load current is equal to or greater than a predetermined current value, or when the time rate of change is equal to or greater than a predetermined time rate of change, the state changes from the first state to the second state. 7. The friction stir welding apparatus according to claim 6, further comprising changing means. The detecting means is
(A) a first state and a second state,
A sensor that detects by the moving amount of the rotor by the linear driving means or by the image of the rotor and the workpiece by the television camera,
7. The friction stir welding apparatus according to claim 6, further comprising: (b) changing means for changing from the first state to the second state in response to an output of the sensor. The detecting means is
Time measuring means for measuring the passage of time by means of the linear driving means of the rotor,
7. The friction stir welding apparatus according to claim 6, further comprising a change unit that changes from the first state to the second state in response to an output of the time measurement unit. Friction stir welding that presses the high-speed rotating rotor against the workpiece, partially softens the workpiece by frictional heat between the rotor and the workpiece, agitates the softened part, and welds the workpiece In the device,
Rotation driving means for driving the rotor at a variable rotation speed around its axis,
Linear drive means for moving the rotor in its axial direction;
A plurality of workpieces are stacked, and a detecting means for detecting a state in which the rotor is in pressure contact with the surface of the uppermost workpiece or near the boundary of the stacked workpieces,
Control means for responding to the output of the detecting means and reducing the rotational speed of the rotary drive means or the pressing force of the linear drive means as the friction stir operation progresses based on the output. apparatus. The friction stir welding apparatus according to claim 5, wherein the friction stir welding is spot welding.

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