Patent Description:
<CIT> discloses a friction stir welding device according to the preamble of claim <NUM> and a friction stir welding method according to the preamble of claim <NUM>.

As a friction stir welding tool used when performing friction stir welding, a type having a rotary shoulder which rotates integrally with a probe, and a type having a rotating probe and a non-rotatable stationary shoulder are known.

As a friction stir welding tool provided with a fixed shoulder, in order to perform friction stir welding of corner portions (inner corner portions) between workpieces to be welded, a tool having a fixed shoulder including a surface abutting corner portions of both workpiece surfaces (see, for example, Patent Document <NUM>) is known.

Further, a technique called AdStir which forms a fillet (reinforcement) at a corner portion after welding by adding a filler when performing friction stir welding of the corner portion using a friction stir welding tool having a fixed shoulder has also been suggested (e.g., see Non-Patent Document <NUM>).

However, in the friction stir welding performed while applying a filler using a friction stir welding tool equipped with a fixed shoulder, for example, when a corner portion between workpieces made of aluminum is set as a welding target, and when the welded length is relatively long and in the order of meters, it has become apparent in recent years that defects such as roughness may occur on the surface of a fillet which is formed.

As a result of research conducted by the inventors of the present invention, such defects are thought to be caused by the fact that the material of the workpiece and the material of the filler softened and stirred by the probe adhere to the fixed shoulder at the time of friction stir welding or the adhered substance scratches the surface of the fillet.

Thus, the present disclosure provides a friction stir welding device and a friction stir welding method capable of inhibiting occurrence of defects on the surface of a fillet formed along a welding portion, when performing friction stir welding of a welding portion between workpieces, while adding a filler, using a friction stir welding tool provided with a fixed shoulder.

In order to solve the above problem, a friction stir welding device according to claim <NUM> and a friction stir welding method according to claim <NUM> are disclosed.

According to the friction stir welding device and the friction stir welding method of the present disclosure, it is possible to inhibit occurrence of defects on the surface of a fillet formed along a welding portion, when performing friction stir welding of a welding portion between workpieces, while adding a filler, using a friction stir welding tool provided with a fixed shoulder.

A friction stir welding device and a friction stir welding method according to the present disclosure will be described with reference to the drawings.

First, the friction stir welding method of the present disclosure will be briefly described with reference to <FIG>.

As illustrated in <FIG>, the friction stir welding method of the present disclosure uses a friction stir welding tool <NUM> of a type including a probe <NUM> and a fixed shoulder <NUM>. When friction stir welding is performed, the friction stir welding tool <NUM> immerses the probe <NUM> into a welding portion between workpieces W1 and W2, for example, a corner portion c in <FIG>, in a rotationally driven state, thereby forming a stirring region s of the materials of the workpieces W1 and W2 around the probe <NUM>. At this time, the fixed shoulder <NUM> is disposed with a gap <NUM> between the fixed shoulder <NUM> and the surfaces P1 and P2 of the respective workpieces W1 and W2, and the gap <NUM> is always maintained while the probe <NUM> is moved along the corner portion c to perform friction stir welding.

Furthermore, during operation of friction stir welding, a filler <NUM> is supplied to the stirring region s. An amount of supply of the filler <NUM> is larger than the volume of the fillet <NUM> geometrically obtained from a cross-sectional shape of the fillet (reinforcement) <NUM> per the same unit length, indicated by the alternate long and short dash line in <FIG>, which is formed at the corner portion c after the friction stir welding when the friction stir welding advances by a certain unit length.

When supplying the filler <NUM>, the materials of the workpieces W1 and W2 and the material of the filler <NUM> are softened and stirred by the probe <NUM> in the stirring region s during operation of the friction stir welding, and the fillet <NUM> is formed from a softened substance <NUM> (hereinafter referred to as "softened material substance <NUM>") in which the materials of the workpieces W1 and W2 and the material of the filler <NUM> are mixed with each other. At the same time, surplus softened material substance <NUM> is made to flow into the gap <NUM> in a softened state. Therefore, at the time of friction stir welding, a layer of the softened material substance <NUM> is formed between the fixed shoulder <NUM> relatively moving with respect to the workpieces W1 and W2 and the surfaces P1 and P2 of the workpieces W1 and W2 facing the fixed shoulder <NUM>.

<FIG> is a schematic cross-sectional side view illustrating a first embodiment of the friction stir welding device, and <FIG> is a partially cut schematic front view. <FIG> are enlarged views of the friction stir welding tool according to the present embodiment. <FIG> is a front view, <FIG> is a cut side view, and <FIG> is a rear view thereof. <FIG> are enlarged views of the filler supply unit in the present embodiment. <FIG> is a side view, and <FIG> is a view taken along the line B-B of <FIG>.

Components the same as those in <FIG> are denoted by the same reference numerals, and description thereof will not be provided.

As illustrated in <FIG> and <FIG>, the friction stir welding device <NUM> of the present embodiment includes a friction stir welding tool <NUM> having a probe <NUM> and a fixed shoulder <NUM>, a main shaft unit <NUM> having a rotational driving device <NUM> of the probe <NUM> and mounted on the first end side serving as a leading end side of the friction stir welding tool <NUM>, a three-axes type gate main shaft positioning mechanism (moving unit) <NUM> which relatively moves the main shaft unit <NUM> and the friction stir welding tool <NUM> relative to the corner portion c between the workpieces W1 and W2, a control device <NUM> of the main shaft positioning mechanism <NUM>, and a filler supply unit <NUM> which supplies the filler <NUM> into the stirring region s of the materials of the workpieces W1 and W2 at the time of friction stir welding of the corner portion c.

When performing friction stir welding of the corner portion c, a direction (a rightward direction in <FIG> and <FIG>) in which the friction stir welding tool <NUM> relatively advances with respect to the corner portion c is hereinafter referred to as a welding direction.

As illustrated in <FIG>, the friction stir welding tool <NUM> is provided with the probe <NUM> capable of rotational driving, and the fixed shoulder <NUM> disposed on the outer periphery on the proximal end side of the probe <NUM>.

The probe <NUM> is disposed in an angular attitude in which the axial direction is parallel to the bisector of the angle at the corner portion c between the workpieces W1 and W2. In this embodiment, the corner portion c is a right angle, and both the workpieces W1 and W2 are inclined by <NUM> degrees from the vertical direction. Therefore, the axial center of the probe <NUM> is disposed in the vertical direction while being inclined at <NUM> degrees with respect to both the workpieces W1 and W2.

An end portion of the fixed shoulder <NUM> disposed closer to the leading end of the probe <NUM> has a cone shape (a V shape) which includes two workpiece facing surfaces 14a and 14b disposed opposite to the surfaces P1 and P2 of the workpieces W1 and W2 on both sides of the corner portion c. Furthermore, as illustrated in <FIG>, a cavity forming cut <NUM> is provided in a portion which is a top portion of the mountain shape formed by the workpiece facing surfaces 14a and 14b, on the front side of the probe <NUM> in the welding direction. The cavity forming cut <NUM> forms a cavity <NUM> for inserting the filler <NUM> between the surfaces P1 and P2 of the workpieces W1 and W2. Further, in <FIG>, the cavity <NUM> illustrates an example in which the cross section perpendicular to the welding direction has a right-angled isosceles triangle shape. However, as long as the filler <NUM> can be inserted, the cavity <NUM> may have a shape corresponding to the cross section of the filler <NUM>, and is not limited to the illustrated shape.

On the other hand, as illustrated in <FIG> and <FIG>, a fillet forming cut portion <NUM> is provided in the portion which is the top portion of the mountain shape of the fixed shoulder <NUM>, on the rear side of the probe <NUM> in the welding direction. The fillet forming cut portion <NUM> is cut in a shape corresponding to a desired cross-sectional shape so that the fillet <NUM> having a desired cross-sectional shape is formed at the corner portion c after welding. In the present embodiment, since the fillet <NUM> has a cross section which is a right-angled isosceles triangle, the cut shape of the fillet forming cut portion <NUM> also has a shape corresponding thereto. Therefore, for example, in the case of forming the fillet <NUM> with a shape having an R (curved surface) at the corner portion c after welding, the fillet forming cut portion <NUM> may have a shape corresponding to the cross-sectional shape of the fillet <NUM> having a curved surface.

As illustrated in <FIG> and <FIG>, the friction stir welding tool <NUM> is attached to the leading end side of the main shaft unit <NUM>. In this state, the fixed shoulder <NUM> is held in the main shaft unit <NUM> in a state in which rotation is inhibited, and the probe <NUM> can be rotationally driven by the rotational driving device <NUM>.

As illustrated in <FIG> and <FIG>, the main shaft positioning mechanism <NUM> includes an X-axis table <NUM> for placing the workpieces W1 and W2 as the welding targets on a stand <NUM> and moving them along the extending direction of the corner portion c.

Furthermore, a portal frame <NUM> that straddles the X-axis table <NUM> is installed on the stand <NUM>, and a Z-axis table <NUM> for controlling the position of the main shaft unit <NUM> in the vertical direction (Z-axis direction) is attached to the portal frame <NUM>. A Y-axis table <NUM> is attached to the Z-axis table <NUM>. The Y-axis table <NUM> controls the position of the main shaft unit <NUM> in a horizontal direction (hereinafter referred to as the Y-axis direction) perpendicular to the movement direction of the X-axis table <NUM>. The main shaft unit <NUM> is attached to the Y-axis table <NUM> in a state of being disposed above the X-axis table <NUM>.

The X-axis table <NUM> includes a guide rail <NUM> provided on the stand <NUM> to extend in the X-axis direction, a movement table <NUM> as a horizontal flat plate shape slidably attached to the guide rail <NUM> via a guide block <NUM>, and a ball screw mechanism <NUM> as an X-axis direction linear motion mechanism which moves the movement table <NUM> in the longitudinal direction of the guide rail <NUM>.

The ball screw mechanism <NUM> includes a drive motor <NUM> such as a servo motor, a speed reducer <NUM> attached to the output side thereof, a screw shaft <NUM> connected to the output side of the speed reducer <NUM>, and a nut member <NUM> attached to the screw shaft <NUM>.

Further, the ball screw mechanism <NUM> is installed between the movement table <NUM> on the stand <NUM> in a posture that a screw shaft <NUM> extends parallel to the guide rail <NUM>, and the nut member <NUM> is attached to the movement table <NUM> via a mounting member <NUM>.

Thus, in the ball screw mechanism <NUM>, by rotationally driving the screw shaft <NUM> via the speed reducer <NUM> by the drive motor <NUM>, and by switching the rotation direction thereof, the X-axis table <NUM> can move the nut member <NUM> and the movement table <NUM> back and forth together in the X-axis direction. At this time, the X-axis table <NUM> can control the position or movement speed of the workpieces W1 and W2 placed and held on the upper side of the movement table <NUM>, on the basis of a detection signal for the rotation amount of the drive motor <NUM> or a position detection signal for the nut member <NUM> or the movement table <NUM> provided by a position detection unit (not illustrated) such as a linear gauge or a displacement sensor.

On the upper side of the movement table <NUM>, a jig <NUM> for holding the workpiece W1 and the workpiece W2 to be welded over the entire length is provided. For example, as illustrated in <FIG>, the jig <NUM> includes a V-shaped groove <NUM> on the upper surface side, and places the workpieces W1 and W2 on the two inclined surfaces of the groove <NUM> in a posture in which the end surface of the other workpiece W2 abuts the end edge of one workpiece W1.

Furthermore, the jig <NUM> includes a large number of pressing members <NUM> arranged in the X-axis direction on the upper end sides of each inclined surface, and presses and fixes the workpieces W1 and W2 to the inside of the groove <NUM> with the pressing members <NUM>. As a result, the position of the corner portion c between the workpieces W1 and W2 is maintained over the entire length in the X-axis direction by the jig <NUM>.

Holding of the workpieces W1 and W2 using the jig <NUM> is performed using a pressing load in the Z-axis direction for immersing the probe <NUM> of the friction stir welding tool <NUM> into the corner portion c at the time of friction stir welding, and a holding force prevents the workpieces W1 and W2 from being displaced even if a load in the X-axis direction acts when moving the probe <NUM> in the state of being immersed into the corner portion c in the longitudinal direction of the corner portion c.

Further, <FIG> illustrates an example of a case where the corner portion c of the workpiece W1 and the workpiece W2 is a corner joint. However, the corner portion c serving as a welding portion may be a T-shaped joint, a lap joint or a cross joint. In these cases, depending on the posture of the workpiece W1 and the workpiece W2 when the surfaces P1 and P2 of the workpiece W1 and the workpiece W2 are disposed to be inclined surfaces on both sides of the corner portion c, the shape of the jig <NUM> may be appropriately changed.

Further, the jig <NUM> is may be held in a posture in which the surface P1 of the workpiece W1 and the surface P2 of the workpiece W2 on either side of the corner portion c are held in a posture of being inclined at equal inclination angles from the vertical direction. However, depending on the shape or the arrangement of the welding when forming the corner portion c by the workpiece W1 and the workpiece W2, the jig <NUM> may be held in a state in which the surface P1 of the workpiece W1 and the surface P2 of the workpiece W2 form inclination angles different from each other with respect to the vertical direction.

As illustrated in <FIG> and <FIG>, the Z-axis table <NUM> is provided with a guide rail <NUM> in the vertical direction (Z-axis direction) installed in the portal frame <NUM>, a movement table <NUM> as a flat plate shape along a vertical plane perpendicular to the X-axis direction slidably attached to the guide rail <NUM> via a guide block <NUM>, and a ball screw mechanism <NUM> as a Z-axis direction linear motion mechanism for moving the movement table <NUM> in the longitudinal direction of the guide rail <NUM>.

Further, the screw shaft <NUM> is installed in a posture of extending parallel to the guide rail <NUM> between the ball screw mechanism <NUM> and the movement table <NUM> on the surface of the installation side of the Z-axis table <NUM> of the portal frame <NUM>, and the nut member <NUM> is attached to the movement table <NUM> via the load cell <NUM> and the attachment member <NUM>.

Thus, in the ball screw mechanism <NUM>, by rotationally driving the screw shaft <NUM> via the speed reducer <NUM> by the drive motor <NUM>, and by switching the rotation direction thereof, the Z-axis table <NUM> can move the nut member <NUM> and the movement table <NUM> back and forth together in the vertical direction which is the Z-axis direction. At this time, on the basis of the detection signal of the rotation amount of the drive motor <NUM>, or the position detection signal of the nut member <NUM> or the movement table <NUM> provided by a position detection unit (not illustrated) such as a linear gauge or a displacement sensor, the Z-axis table <NUM> can control the vertical positions of the main shaft unit <NUM> and the friction stir welding tool <NUM> held on the movement table <NUM> via the Y-axis table <NUM> as will be described later.

Further, the Z-axis table <NUM> can detect the pressing load in the direction toward the corner portion c applied to the friction stir welding tool <NUM> at the time of friction stir welding, on the basis of the detection signal of the load cell <NUM>.

Although not illustrated, in the Z-axis table <NUM>, a gravity compensating mechanism (also referred to as a self-weight compensating mechanism and a weight compensating mechanism) which supports the self-weight of the movement table <NUM> and the weight of parts moving up and down together with the movement table <NUM> may be interposed between the portal frame <NUM> and the movement table <NUM>. According to this configuration, it is possible to directly detect the pressing load at the corner portion c applied to the friction stir welding tool <NUM> by the load cell <NUM>.

As illustrated in <FIG> and <FIG>, the Y-axis table <NUM> is provided with a guide rail <NUM> in the Y-axis direction installed on the movement table <NUM> of the Z-axis table <NUM>, a movement table <NUM> as a flat plate shape along a vertical plane perpendicular to the X-axis slidably attached to the guide rail <NUM> via a guide block <NUM>, and a ball screw mechanism <NUM> as a Y-axis direction linear motion mechanism for moving the movement table <NUM> in the longitudinal direction of the guide rail <NUM>.

The ball screw mechanism <NUM> includes a drive motor <NUM> such as a servo motor, a screw shaft <NUM> connected to the output side thereof, and a nut member <NUM> attached to the screw shaft <NUM>.

Further, the ball screw mechanism <NUM> is installed between the movement table <NUM> and the movement table <NUM> in a posture in which the screw shaft <NUM> extends parallel to the guide rail <NUM>, and the nut member <NUM> is attached to the movement table <NUM> via the attachment member <NUM>. The main shaft unit <NUM> is attached to the movement table <NUM>.

Therefore, in the ball screw mechanism <NUM>, by rotationally driving the screw shaft <NUM> by the drive motor <NUM>, and by switching the rotation direction thereof, the Y-axis table <NUM> can move the nut member <NUM> and the movement table <NUM> back and forth together in the Y-axis direction. At this time, the Y-axis table <NUM> can control the positions in the Y-axis direction of the main shaft unit <NUM> and the friction stir welding tool <NUM> held in the movement table <NUM>, on the basis of the detection signal of the rotation amount of the drive motor <NUM> or the position detection signal of the nut member <NUM> or the movement table <NUM> provided by a position detection unit (not illustrated) such as a linear gauge or a displacement sensor.

The control device <NUM> of the main shaft positioning mechanism <NUM> has a function of controlling the positions in the vertical direction and the horizontal direction of the friction stir welding tool <NUM> attached to the main shaft unit <NUM> via the control of the Z-axis table <NUM> and the Y-axis table <NUM>, within a plane perpendicular to the direction in which the corner portion c between the workpieces W1 and W2 extends.

The control device <NUM> has a function of controlling the position in the X-axis direction of the corner portion c of the workpieces W1 and W2 held on the movement table <NUM> via the jig <NUM>, via the control of the X-axis table <NUM>.

Further, the control device <NUM> controls the rotational driving of the probe <NUM> via the control of the rotational driving device <NUM> of the main shaft unit <NUM>.

When performing the friction stir welding, as illustrated in Fig. <NUM>, first, the control device <NUM> disposes the corner portion c of the workpieces W1 and W2 via the control of the X-axis table <NUM> such that the starting end side of the friction stir welding set at the first end (one end) side (left end side of <FIG>) in the longitudinal direction is located below the main shaft unit <NUM>. Next, in the above state, the control device <NUM> starts the rotational driving of the probe using the rotational driving device <NUM>, and immerses the probe <NUM> into the corner portion c via the control of the Y-axis table <NUM> and the Z-axis table <NUM>. Next, the control device <NUM> starts the movement of the movement table <NUM> of the X-axis table <NUM>, relatively moves the probe <NUM> along the corner portion c between the workpieces W1 and W2, and performs the friction stir welding of the corner portion c. Thereafter, when the probe <NUM> reaches the terminal end side of the friction stir welding set on the second end (the other end) side (the right end side in <FIG>) in the longitudinal direction of the corner portion c, the control device <NUM> stops the movement table <NUM>, and then controls the Z-axis table <NUM> such that the probe <NUM> is extracted from the corner portion c.

Furthermore, when performing the friction stir welding as described above, the control device <NUM> has the function of holding the position of the fixed shoulder <NUM> of the friction stir welding tool <NUM> at a position separated by the gap <NUM> from the surfaces P1 and P2 of the workpieces W1 and W2 as illustrated in <FIG>, via the control of the Z-axis table <NUM>.

In order to hold the fixed shoulder <NUM> at a position where the gap <NUM> is formed, the control device <NUM> controls the position of the fixed shoulder <NUM> such that it is at a position separated from the surfaces P1 and P2 by the desired gap <NUM> as the target position, on the basis of information on the positions of the surfaces P1 and P2 of the workpieces W1 and W2 held on the X-axis table <NUM>.

Further, when the probe <NUM> is immersed into the corner portion c, the amount of immersion of the probe <NUM> increases or decreases in accordance with the magnitude of the pressing load applied to the probe <NUM> by the Z-axis table <NUM>. Further, in a state in which the probe <NUM> is immersed into the corner portion c, the distance between the workpiece facing surfaces 14a and 14b of the fixed shoulder <NUM> and the surfaces of the workpieces W1 and W2 is ascertained on the basis of the known positional relation between the probe <NUM> and the fixed shoulder <NUM>. Therefore, the control device <NUM> may hold the fixed shoulder <NUM> at a position where the desired gap <NUM> is formed with respect to the surfaces PI and P2 of the workpieces W1 and W2, by controlling the pressing load of the probe <NUM> detected by the load cell <NUM> in the state of immersing the probe <NUM> being immersed into the corner portion c.

The lower limit and the upper limit of the size of the gap <NUM> are set in a range of sizes in which the softened material substance <NUM> softened and stirred by the probe <NUM> flows into the gap <NUM> while being softened and can fill the gap <NUM> between the workpiece facing surfaces 14a and 14b of the fixed shoulder <NUM> and the surfaces P1 and P2 of the workpieces W1 and W2.

That is, the softened material substance <NUM> stirred by the probe <NUM> has fluidity, but it is only a solid and not liquid. Therefore, when the gap <NUM> is too small, the resistance when the softened material substance flows into the gap <NUM> increases. In this case, the softened material substance <NUM> cannot spread into the gap <NUM>. Therefore, the lower limit of the size of the gap <NUM> depends on the degree of fluidity of the softened material substance <NUM>. When the workpieces W1 and W2 and the material of the filler <NUM> are aluminum (aluminum alloy), it may be that the size of the gap <NUM> be set to <NUM> or more.

On the other hand, the upper limit of the size of the gap <NUM> is determined as follows.

In order for the softened material substance <NUM> entering the gap <NUM> to spread throughout the gap <NUM> while having fluidity, heat (frictional heat) generated by the rotating probe <NUM> needs to be transmitted to the entire softened material substance <NUM> entering the gap <NUM> under temperature conditions that can maintain the softened state.

The amount of heat generated by the probe <NUM> depends on the operation conditions of the friction stir welding such as the structure of the probe <NUM>, the rotational speed, the amount of immersion into the corner portion c, and the relative movement speed with respect to the corner portion c. Therefore, at the time of friction stir welding, the amount (volume) of the softened material substance <NUM> that can be softened by the heat generated by the probe <NUM> has an upper limit, depending on the properties of the material or heat transfer characteristics. Therefore, the upper limit of the volume of the gap <NUM> in which surplus softened material substance <NUM> of the softened material substance <NUM> used for forming the fillet <NUM> can flow in and spread may also be determined. Therefore, by dividing the upper limit value of the volume of the gap <NUM> by the area of the workpiece facing surfaces 14a and 14b of the fixed shoulder <NUM>, the upper limit value of the size of the gap <NUM> is determined.

After the friction stir welding, the solidified substance of the softened material substance <NUM> that has entered the gap <NUM> is in a state of protruding from the surfaces P1 and P2 of the workpieces W1 and W2. Therefore, depending on the kinds of the workpieces W1 and W2, in some cases, it is desired to inhibit stress concentration on the protruding portions formed on the surfaces P1 and P2. The upper limit value of the size of the gap <NUM> may be set from this point of view.

When the size of the gap <NUM> is determined in this way, the volume per unit length in the advancement direction of the friction stir welding of the gap <NUM> is determined. Therefore, the supply amount of the filler <NUM> is set to be equal to or higher than an amount obtained by adding the capacity per unit length in the welding direction of the gap <NUM> to the volume per unit length of the fillet <NUM> formed at the corner portion c.

For example, the filler supply unit <NUM> may supply wire-shaped filler <NUM> as illustrated in <FIG> to the stirring region s through the cavity <NUM> formed between the workpieces W1 and W2 by the cavity forming cut <NUM> of the fixed shoulder <NUM> illustrated in <FIG>.

Therefore, as illustrated in <FIG>, the filler supply unit <NUM> is equipped with a bracket <NUM> provided at the lower end side (leading end side) of the main shaft unit <NUM> so as to be disposed on the front side of the attachment position of the friction stir welding tool <NUM> in the welding direction.

On the lower side of the bracket <NUM>, as illustrated in <FIG>, a frame <NUM> which holds a roller <NUM> for pressing the filler <NUM> from above is disposed. A plurality of, for example, two guide rods <NUM> extending vertically are erected on the upper side of the frame <NUM>. The guide rods <NUM> are inserted into guide holes (not illustrated) provided in the bracket <NUM> in the vertical direction from below, and a retaining member <NUM> is attached to the upper end side. A spring <NUM> as a pressing portion is fitted to the outer periphery of the guide rod <NUM> between the upper surface of the frame <NUM> and the lower surface of the bracket <NUM>.

In the filler supply unit <NUM>, at the time of the friction stir welding, when the main shaft unit <NUM> is lowered to bring the probe <NUM> close to the corner portion c in a state in which the filler <NUM> is disposed in advance along the corner portion c located on the front side of the friction stir welding tool <NUM> in the welding direction, the roller <NUM> comes into contact with the filler <NUM> from above. From this state, when the main shaft unit <NUM> is further moved downward to a position where the probe <NUM> is immersed into the corner portion c, the spring <NUM> contracts between the frame <NUM> of the roller <NUM> and the bracket <NUM>, and the roller <NUM> can be pressed and pressurized against the filler <NUM> from above by a restoring force of the contracted spring <NUM>.

Further, the spring <NUM> is described as an example of the pressing portion, but anything may be adopted as long as it is possible to apply a pressing force in a direction toward the filler <NUM> to the roller <NUM>, any other type of pressing portion such as a gas spring or a fluid pressure cylinder may be adopted, and a pressing portion such as an actuator which actively generates a pressing force may be adopted.

Therefore, the filler <NUM> is fixed to the corner portion c. In this state, when the friction stir welding of the corner portion c by the friction stir welding tool <NUM> advances, the filler <NUM> is guided to the cavity <NUM> formed between the cavity forming cut15 of the fixed shoulder <NUM> and the surfaces P1 and P2 of the workpieces W1 and W2, and is introduced into the stirring region s.

Furthermore, the filler supply unit <NUM> applies a pressure of at least <NUM> MPa or more to the leading end side of the filler <NUM> supplied to the stirring region s in the direction perpendicular to the supply direction.

In the present embodiment, the filler <NUM> is supplied to the stirring region s with an advancement of the friction stir welding of the corner portion c using the friction stir welding tool <NUM>, in the state of being pressed against the corner portion c. Therefore, in the present embodiment, the frictional force (maximum frictional force) generated between the filler <NUM> and the surfaces P1 and P2 of the workpieces W1 and W2 on both sides of the corner portion c is the product of the pressure applied to the surfaces P1 and P2 as the frictional surfaces, that is the areas of the surfaces P1 and P2 and the coefficient of friction and is the product of the pressure applied to the leading end side of the filler <NUM> and the cross-sectional area of the filler <NUM>. Therefore, the pressing force is set when pressing the filler <NUM> by the roller <NUM> in consideration of the friction coefficient between the filler <NUM> and the surfaces P1 and P2 such that a pressure of at least <NUM> MPa or more is applied to the leading end side of the filler <NUM> in the direction perpendicular to the supply direction of the filler <NUM>. Further, the upper limit of the pressure applied to the leading end side of the filler <NUM> supplied to the stirring region s is defined by a buckling strength from the position pressed by the roller <NUM> of the filler <NUM> to the leading end.

In the present embodiment, the filler <NUM> is fixed to the corner portion c. Therefore, in order to obtain the supply amount of the filler <NUM> described above, the cross-sectional area of the filler <NUM> is set to be equal to or larger than the area obtained by adding the cross-sectional area in the cross section perpendicular to the welding direction of the of the gap <NUM> to the cross-sectional area of the fillet <NUM> formed in the corner portion c.

As described above, according to the friction stir welding device <NUM> of the present embodiment, after the probe <NUM> of the friction stir welding tool <NUM> is immersed into the corner portion c between the workpieces W1 and W2, by moving the probe <NUM> along the corner portion c, the corner portion c of the workpieces W1 and W2 is subjected to friction stir welding.

At this time, the fixed shoulder <NUM> of the friction stir welding tool <NUM> is not in contact with the surfaces P1 and P2 of the workpieces W1 and W2. Furthermore, since the softened material substance <NUM> is present in the gap <NUM> between the workpiece facing surfaces 14a and 14b of the fixed shoulder <NUM> and the surfaces P1 and P2 of the workpieces W1 and W2, the solidified matter of the material softened substance <NUM> is prevented from adhering to and accumulating on the fixed shoulder <NUM>. Further, even if the solidified matter of the material softened substance <NUM> adheres to the fixed shoulder <NUM>, the deposit is prevented from adhering to the surface of the fillet <NUM>.

Therefore, according to the friction stir welding device of the present embodiment, when performing the friction stir welding of the corner portion c which is the welding portion between the workpieces W1 and W2, while applying the filler <NUM> using the friction stir welding tool <NUM> including the fixed shoulder <NUM>, it is possible to inhibit occurrence of defects on the surface of the fillet <NUM> formed in the corner portion c.

<FIG> illustrates a second embodiment of the friction stir welding device, and <FIG> are schematic views illustrating another example of the filler supply unit.

Further, in <FIG>, components the same as those illustrated in the first embodiment are denoted by the same reference numerals, and description thereof will not be provided.

A filler supply unit 13a illustrated in <FIG> has a configuration similar to that of the filler supply unit <NUM> of the first embodiment, and a drive motor <NUM> as a rotation drive unit is connected to a roller <NUM>. Although illustrated in <FIG> in a simplified manner, in reality, a power transmission mechanism such as a gear, a chain or a sprocket which transmits a rotational driving force is provided between the drive motor <NUM> and the roller <NUM>.

The direction of rotational driving of the roller <NUM> provided by the drive motor <NUM> is a clockwise direction in <FIG>, and the roller <NUM> imparts a driving force to the filler <NUM> such that the filler <NUM> against which the roller <NUM> is pressed from above is fed in a direction directed to the friction stir welding tool <NUM>.

According to the filler supply unit 13a, by rotationally driving the roller <NUM>, it is possible to actively supply the filler <NUM> to the stirring region s.

A filler supply unit 13b illustrated in <FIG> has a configuration similar to the filler supply unit <NUM> of the first embodiment, and includes a delivery unit <NUM> of the filler <NUM> on the front side of the roller <NUM> in the welding direction.

The delivery unit <NUM> includes, for example, a pair of delivery rollers <NUM> disposed to sandwich the filler <NUM>, and a rotation drive unit (not illustrated) that rotatably drives the delivery rollers <NUM> in directions opposite to each other. The delivery direction of the filler provided by the delivery roller <NUM> is a leftward direction in <FIG>, and the delivery roller <NUM> applies a driving force to the filler <NUM> so that the filler <NUM> is fed in a direction directed toward the friction stir welding tool <NUM>.

According to the filler supply unit 13b, it is possible to actively supply the filler <NUM> delivered from the delivery unit <NUM> to the stirring region s, while guiding the filler <NUM> by the roller <NUM>.

Further, in either case of <FIG>, the filler supply units 13a and 13b apply a pressure of at least <NUM> MPa or more to the leading end side of the filler <NUM> supplied to the stirring region s in the direction perpendicular to the supply direction.

Therefore, according to the filler supply units 13a and 13b of <FIG>, it is possible to use the filler <NUM> having a smaller cross-sectional area than the value obtained by adding the cross-sectional area in the cross section perpendicular to the welding direction of the gap <NUM> to the cross-sectional area of the fillet <NUM> formed in the corner portion c. Therefore, when the supply amount of the filler <NUM> of the first embodiment is set to a predetermined amount, the supply amount of the filler <NUM> in the second embodiment can be set to be equal to or higher than the above-mentioned predetermined amount.

<FIG> illustrates a photograph of a welding portion formed by the conventional friction stir welding, and <FIG> illustrates a photograph of a welding portion formed by the friction stir welding according to the present disclosure. It is possible to understand from <FIG> that a plurality of defects are generated in the welding portion formed by the friction stir welding due to non-formation of the gap <NUM> between the workpiece W1 and the workpiece W2 or insufficient supply of the filler <NUM>. On the other hand, it is possible to understand from <FIG> that a gap <NUM> is formed between the workpiece W1 and the workpiece W2 at the welding portion formed by the friction stir welding according to the present disclosure, and since the supply amount of the filler <NUM> is sufficient, defects are not formed.

Further, although the cross-sectional shape of the filler <NUM> is illustrated as being round, a filler having an angular cross-sectional shape or any other cross-sectional shape may be used. Although the filler <NUM> is described as having a wire shape, it may be rod-like.

Also, the present disclosure is not limited to each of the above embodiments. The first embodiment illustrates a configuration in which the filler supply unit <NUM> fixes the filler <NUM> to the corner portion c, and the filler <NUM> is supplied to the stirring region s relative to advancement of the friction stir welding tool <NUM>. However, a phenomenon in which the filler <NUM> is pushed back in the welding direction by the softened material substance <NUM> existing in the probe <NUM> or the stirring region s formed around the probe <NUM> may occur. In this case, it may be possible to use filler <NUM> having a cross-sectional area which exceeds the area obtained by adding the cross-sectional area in the cross section perpendicular to the welding direction of the gap <NUM> to the cross-sectional area of the fillet <NUM> formed at the corner portion c so that the supply amount of the filler <NUM> becomes the above-mentioned predetermined amount even if the filler <NUM> is pushed back.

In the first embodiment, the workpieces W1 and W2 to be welded by friction stir welding are illustrated as being disposed in a state in which the end surface of the workpiece W2 is in contact with the end edge of the workpiece W1. However, a gap may be formed between the workpiece W1 and the workpiece W2. In this case, the workpieces W1 and W2 may be held by the jig <NUM> in a state in which the workpieces W1 and W2 are disposed with a gap therebetween, and the friction stir welding may be performed in this state. Also, in this case, since the softened material substance <NUM> enters the gap between the workpieces W1 and W2, the supply amount of the filler may be defined by the amount expected to enter the gap.

In the friction stir welding device and the friction stir welding method according to the present disclosure, description has been given of a case where the friction stir welding is performed in a state in which the workpieces W1 and W2 are disposed in the posture in which the corner portion c is open upward. However, the corner portion c between the workpieces W1 and W2 may have any orientation. In this case, the direction in which the corner portion c extends between the workpieces W1 and W2 may be set as the X-axis, and the orientation of the three-dimensional orthogonal coordinate system in which the Y-axis and the Z-axis are set in a plane perpendicular thereto may be disposed in accordance with the postures of the workpieces W1 and W2.

Further, in the friction stir welding device and the friction stir welding method of the present disclosure, the second workpiece is disposed in contact with the end edge of the first workpiece in a posture at an angle intersecting with the surface P1 of the first workpiece, but a case where corner portions c formed on both sides of the second workpiece are subjected to friction stir welding, using two friction stir welding tools disposed on each of the two sides of the second workpiece may be applied thereto.

Furthermore, the friction stir welding device and the friction stir welding method of the present disclosure may be applied to, for example, the friction stir welding of a welding portion in which end portions of flat plate-like workpieces abut against each other. In this case, a friction stir welding tool equipped with a fixed shoulder having a flat workpiece facing surface is used as the friction stir welding tool. In the friction stir welding, since the fillet <NUM> does not exist, the supply amount of the filler <NUM> may be set to be equal to or higher than an amount obtained by adding the volume may be set for filling the gap <NUM> when disposing the fixed shoulder with a gap between it and the surface of each workpiece to the volume may be set for filling the cavity formed at the abutting portion of each workpiece.

As a moving unit for relatively moving the friction stir welding tool <NUM> together with the main shaft unit <NUM> with respect to the corner portion c of the workpieces W1 and W2 in the direction along the corner portion, an example of the main shaft positioning mechanism <NUM> which fixes the portal frame <NUM> supporting the main shaft unit <NUM> and moves the workpieces W1 and W2 has been illustrated. However, for example, any type of moving unit other than the illustrated type may be adopted, such as a unit which fixes the workpieces W1 and W2 and sets the portal frame <NUM> straddling the workpieces as a movement type.

Claim 1:
A friction stir welding device (<NUM>) comprising:
a friction stir welding tool (<NUM>) provided with a fixed shoulder (<NUM>), which is a non-rotatable stationary shoulder, on an outer periphery on a proximal end side of a rotationally drivable probe (<NUM>);
a moving unit (<NUM>) configured to relatively move the friction stir welding tool (<NUM>) to a welding portion between the workpieces (W1, W2) in a direction along the welding portion;
a control device (<NUM>) of the moving unit (<NUM>); and
a filler supply unit (<NUM>) configured to supply a filler (<NUM>) to a stirring region (s) which is stirred by the probe (<NUM>) at the time of friction stir welding of the welding portion,
characterized in that the control device (<NUM>) has a function of holding the fixed shoulder (<NUM>) of the friction stir welding tool (<NUM>) with the probe (<NUM>) immersed into the welding portion, at a position separated by a gap (<NUM>) from surfaces (P1, P2) of the workpieces (W1, W2), while the probe (<NUM>) is moved, and
wherein the control device (<NUM>) controls the position of the fixed shoulder (<NUM>) such that it is at a position separated from the surfaces (P1, P2) by the gap (<NUM>) as a target position, on the basis of information on the positions of the surfaces (P1, P2) of the workpieces (W1, W2).