WO2015146185A1

WO2015146185A1 - Friction stir welding device and friction stir welding method

Info

Publication number: WO2015146185A1
Application number: PCT/JP2015/001752
Authority: WO
Inventors: 藤井　英俊; 林太郎上路; 好昭森貞; 正善釜井; 昇望月; 望月　健児
Original assignee: 国立大学法人大阪大学
Priority date: 2014-03-26
Filing date: 2015-03-26
Publication date: 2015-10-01
Also published as: JP2015182133A; JP6383961B2

Abstract

Provided are a compact friction stir welding device and a friction stir welding method, the compact friction welding device being a portable type that enables site work, and enabling manual operation control. A friction stir welding device is characterized by: using a bobbin-type friction stir welding tool (20) which comprises an upper rotation body (1), a lower rotation body (10), and a stirring shaft (14) formed integrally with the lower rotation body (10), and performs friction stir welding while a material to be welded (48) is put between the upper rotation body (1) and the lower rotation body (10); and being provided with a preheating mechanism (50) for preheating the material to be welded (48).

Description

Friction stir welding apparatus and friction stir welding method

The present invention relates to a friction stir welding apparatus and a friction stir welding method, and more specifically, is a portable compact friction stir welding apparatus that can be applied on-site, and that enables manual operation control. And a friction stir welding method.

Friction stir welding is characterized by the fact that the maximum temperature reached during welding does not reach the melting point of the materials to be joined, and the strength reduction at the joint is small compared to conventional fusion welding, and has recently been rapidly put into practical use. However, while friction stir welding has various excellent characteristics, there is a problem that the apparatus becomes large because a very large tool load, force in the joining direction, and the like act on the material to be joined and the apparatus.

In general friction stir welding equipment, large structural materials, bearings, motors, reducers, etc. are used in order to obtain rigidity that can withstand high loads. Depending on the size. Such a large-sized device is not only costly to manufacture, but also has a limited installation location, which is an obstacle to expand industrial use of friction stir welding.

Also, although fusion welding can be used to repair defects such as cracks, there are problems such as quality degradation due to thermal effects, so repair by friction stir welding with low heat input is expected. However, it is difficult to apply to existing construction such as repair with existing large-scale equipment. For these reasons, downsizing of the friction stir welding apparatus that contributes to the expansion of the application range of the friction stir welding is desired.

In addition, if a low-cost portable friction stir welding device that is small enough to manually control the friction stir welding device is realized, the friction stir welding can be easily used in small and medium-sized businesses and general households. There is a possibility that you will be able to.

On the other hand, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-45980), a rotor that rotates at a high speed is moved in the direction of the rotation axis, the tip portion is pressed against the workpiece, and the tip portion contacts the workpiece. In the friction stir welding apparatus that softens the part with frictional heat by rotation and stirs and joins the objects to be joined, the rotational drive around the rotational axis of the rotor and the straight drive in the rotational axis direction of the rotor are 1 There has been proposed a friction stir welding apparatus characterized in that it is performed with two drive sources.

In the friction stir welding apparatus described in Patent Document 1, the apparatus can be reduced in size and weight by performing the rotational drive and the rectilinear drive of the rotor with one drive source, and one drive source. Therefore, the initial cost and the maintenance cost can be reduced.

Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2009-61479), friction stir welding is performed in which a portion to be joined on a longitudinal side wall portion of a workpiece is frictionally agitated by a friction welding tool in a lateral posture to join the portion to be joined. In the device, a self-propelled vehicle body configured to be capable of self-propelled along the bonded portion on the side wall portion of the object to be bonded, and mounted on the self-propelled vehicle body so as to be rotatable around a reference axis in a lateral orientation, A holding tool holding unit, a rotation driving unit that is mounted on the self-propelled vehicle body and that rotates the tool holding unit around the reference axis, and a displacement driving unit that is mounted on the self-propelled vehicle body and that drives the tool holding unit to be displaced along the reference axis. And a counteracting force generating means for generating a counterforce against the reaction force of the pressing force applied from the tool holding portion and the joining tool to the joined portion by the displacement driving means, and acting on the self-propelled vehicle body by the reaction force of the pressing force. Fall over A counter moment generating means for generating a counter moment against the Mento, friction stir welding apparatus comprising the have been proposed.

The friction stir welding apparatus described in Patent Document 2 includes a self-propelled vehicle body, a tool holding unit, a rotation driving unit, a displacement driving unit, a counter force generation unit, and a counter moment generation unit. The reaction force of the pressing force can be canceled by the counter force generated by the counter force generating means, and the overturning moment can be canceled by the counter moment generated by the counter moment generating means. As a result, the self-propelled vehicle body can be joined in a stable state while preventing overturning.

JP 2002-45980 A JP 2009-61479 A

However, although the friction stir welding apparatus disclosed in Patent Document 1 and Patent Document 2 is somewhat smaller than the conventional friction stir welding apparatus, it can be easily carried and manually operated. There is a big difference from the device that can control the operation.

SUMMARY OF THE INVENTION In view of the above problems in the prior art, an object of the present invention is a portable compact friction stir welding apparatus and friction stir welding method that can be applied on-site, and that enables manual operation control. An object of the present invention is to provide a stir welding apparatus and a friction stir welding method.

In order to achieve the above object, the present inventor conducted extensive research on the process load generated during downsizing and joining of the friction stir welding apparatus, and as a result, a bobbin type friction stir welding tool and a preheating mechanism in which the upper and lower parts are driven separately. It has been found that the use and the like are extremely effective, and the present invention has been achieved.

That is, the present invention
An upper rotating body, a lower rotating body, and a stirring shaft formed integrally with the lower rotating body, and a friction stir welding is performed by sandwiching a material to be joined between the upper rotating body and the lower rotating body. Using the bobbin type friction stir welding tool to perform,
Providing a preheating mechanism for preheating the materials to be joined;
A friction stir welding apparatus characterized by the above is provided.

By using the bobbin type friction stir welding tool, the Z-axis load generated during friction stir welding (substantially perpendicular to the surface of the material to be joined) is offset inside the bobbin type friction stir welding tool. . Therefore, it is possible to reduce the size, rigidity, and the like of the main body structure of the friction stir welding apparatus that holds the tool motor and the stage portion that fixes the material to be joined.

In the friction stir welding apparatus of the present invention, the rotation speeds of the upper rotating body and the lower rotating body can be set independently, and the rotation directions of the upper rotating body and the lower rotating body are opposite to each other. It is preferable that By rotating the upper rotating body and lower rotating body of the bobbin type friction stir welding tool in opposite directions and performing friction stir welding, the tool torque can be offset and the lateral vibration of the tool during friction stir welding is suppressed. can do.

The friction stir welding apparatus according to the present invention includes a preheating mechanism for preheating the materials to be joined, and the preheating mechanism is disposed in front of the bobbin type friction stir welding tool in the advancing direction, and the preheated by the preheating mechanism. It is preferable to induce the traveling direction of the bobbin type friction stir welding tool by softening the bonding material.

Since the strength of the material to be joined in the preheating region is lower than that in the non-preheating region, the process load during the friction stir welding can be effectively reduced. In addition, by selectively preheating the front of the bobbin type friction stir welding tool in the direction of travel, the direction of travel of the bobbin type friction stir welding tool can be induced.

In the friction stir welding apparatus of the present invention, it is preferable that the preheating mechanism is an energization heating method. Compared with laser irradiation, high-frequency heating, and the like, energization heating can be suitably used from the viewpoint of realizing an inexpensive friction stir welding apparatus downsized because the apparatus is extremely inexpensive and small.

Furthermore, in the friction stir welding apparatus of the present invention,
The upper rotating body has a convex shape;
The lower rotating body has a concave shape;
The convex portion of the upper rotating body is inserted into the concave portion of the lower rotating body,
Is preferred. When the material to be joined passes through the gap between the convex portion and the concave portion of the upper rotating body during the friction stir welding, a complicated flow having various directions is generated, and the crystal orientation in the stirring portion can be reduced. In particular, in magnesium and magnesium alloys having a hexagonal close-packed structure, it is known that orientation is likely to occur in the stirring portion, and the joint strength is reduced by the orientation, and the friction stir welding apparatus of the present invention is preferably used. be able to.

Here, in the friction stir welding apparatus according to the present invention, contrary to the friction stir welding apparatus, the upper rotating body has a concave shape, the lower rotating body has a convex shape, and the lower rotating body has a convex shape. The part may be designed to be inserted into the recess of the upper rotating body.

In the friction stir welding apparatus according to the present invention, the force (Fx) in the joining direction applied to the bobbin type friction stir welding tool during the friction stir welding, the lateral force (Fy) perpendicular to the joining line, and the joining line It is preferable that the perpendicular force (Fz) in the perpendicular direction is 10 kgf or less, and it is preferable to manually control the advancing direction of the bobbin type friction stir welding tool during friction stir welding.

The present invention also provides:
Using a bobbin type friction stir welding tool having an upper rotating body, a lower rotating body, and a stirring shaft formed integrally with the lower rotating body,
Sandwiching the material to be joined between the upper rotating body and the lower rotating body;
Rotating the upper rotating body and the lower rotating body in opposite directions;
Moving the bobbin-type friction stir welding tool,
A preheating mechanism is disposed in front of the bobbin type friction stir welding tool in the traveling direction,
Inducing the direction of travel of the bobbin type friction stir welding tool by softening the material to be joined by the preheating,
A friction stir welding method characterized by the above is also provided.

The traveling direction of the bobbin type friction stir welding tool is preferably controlled manually, and the material to be joined is preferably aluminum or an aluminum alloy.

It should be noted that the friction stir welding method of the present invention can be suitably implemented using the friction stir welding apparatus of the present invention.

According to the present invention, a portable compact friction stir welding apparatus and friction stir welding method capable of on-site construction, and a small friction stir welding apparatus and friction stir welding method that enable manual operation control are provided. Can do.

It is a side view which shows an example of the upper rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows an example of the upper rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a side view which shows an example of the lower rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows an example of the lower rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a side view which shows an example of the tool for bobbin type friction stir welding used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows an example of the tool for bobbin type friction stir welding used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram of the joining state by the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a side view which shows another example of the upper rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows another example of the upper rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a side view which shows another example of the lower rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is a top view which shows another example of the lower rotary body used with the friction stir welding apparatus which concerns on one Embodiment of this invention. 1 is a schematic side view of a friction stir welding apparatus according to an embodiment of the present invention. 1 is a schematic front view of a friction stir welding apparatus according to an embodiment of the present invention. It is a conceptual diagram of the preheating mechanism used with the friction stir welding apparatus which concerns on one Embodiment of this invention. It is an external appearance photograph of the friction stir welding apparatus produced in the Example. It is an external appearance photograph of the upper rotating body and lower rotating body which were produced in the Example. It is a load cell layout for measuring a process load at the time of friction stir welding. It is a measured value of the joining direction load Fx. This is a measured value of the lateral load Fy. It is a conceptual diagram of the process load applied to a sample fixing stand. It is the measured value of the lateral load Fy at various upper rotating body rotational speeds. It is a diagram which shows the temperature change of the to-be-joined material by a preheating mechanism. It is a measured value of the process load at the time of friction stir welding with and without preheating. It is an external appearance photograph of the sample obtained by friction stir welding with preheating.

Hereinafter, representative embodiments of the friction stir welding apparatus and the friction stir welding method of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions and ratios of the components shown may be different from the actual ones.

(1) Friction stir welding apparatus (A) Bobbin type friction stir welding tool FIGS. 1 and 2 are a side view and a plan view showing an example of an upper rotating body used in a friction stir welding apparatus according to an embodiment of the present invention. It is. The upper rotating body 1 has a tool mounting portion 2 and an upper shoulder portion 4. Further, the tool mounting portion 2 is provided with a mounting hole 6 for fixing the upper rotating body 1 to the bottom surface of the spindle.

The upper shoulder portion 4 has a cylindrical shape and can pass through a stirring shaft of a lower rotating body described later. Here, the bottom area of the upper shoulder portion 4 may be appropriately determined in consideration of the heat input required for the material to be joined, the motor capacity for rotating the upper shoulder portion 4, and the like.

3 and 4 are a side view and a plan view showing an example of the lower rotating body used in the friction stir welding apparatus according to the embodiment of the present invention. In the lower rotating body 10, a lower shoulder portion 12 and an agitation shaft 14 are integrally formed, and the lower shoulder portion 12 is connected to the agitation shaft 14 via a probe portion 16.

From the viewpoint of reducing the process load during friction stir welding, it is preferable to reduce the diameters of the upper shoulder portion 4 and the lower shoulder portion 12. Here, when the heat input necessary for good friction stir welding is insufficient, the rotational speeds of the upper shoulder portion 4 and the lower shoulder portion 12 may be increased.

The length of the probe portion 16 may be determined by the thickness of the material to be joined, and is preferably about the same as the thickness of the material to be joined or about 0.1 to 0.3 mm shorter than the thickness of the material to be joined. The diameter of the probe part 16 may be determined in consideration of the process load applied to the probe part 16 during joining and the plastic flow characteristics of the materials to be joined. When the process load increases, it is necessary to increase the diameter in order to prevent breakage from the probe portion 16, and when the material to be joined is difficult to plastically flow, it is necessary to decrease the diameter in order to prevent formation of defects in the stirring portion. .

Here, by making the surface of the probe portion 16 into a screw shape, the plastic flow behavior in the stirring portion can be controlled. When the rotation direction of the probe portion 16 is clockwise (clockwise: CW), the shape is a left screw, and when it is counterclockwise (counterclockwise: CCW), the shape of the probe is the right screw. The flow can be promoted, and the formation of defects and the generation of burrs in the stirring section can be suppressed. In the case of a bobbin type friction stir welding tool, since the probe portion 16 penetrates the material to be joined, it is preferable to change the direction of the screw up and down from the approximate center in the length direction of the probe portion 16 (to be joined). It promotes plastic flow downward from the surface of the material and upward from the back surface).

Furthermore, the plastic flow behavior can also be controlled by making the bottom surface (surface contacting the material to be joined) of the upper shoulder portion 4 and / or the lower shoulder portion 12 into a screw shape. In this case, it is preferable to form a screw so that the plastic flow becomes inward of the shoulder portion with the rotation of the upper shoulder portion 4 and / or the lower shoulder portion 12 (if the plastic flow becomes outward, the burrs Amount will increase).

5 and 6 are a side view and a plan view showing an example of a bobbin type friction stir welding tool used in the friction stir welding apparatus according to the embodiment of the present invention. The bobbin type friction stir welding tool 20 includes an upper rotating body 1 and a lower rotating body 10, and the stirring shaft 14 of the lower rotating body 10 passes through the center of the upper rotating body 1.

FIG. 7 is a conceptual diagram of a joining state using the bobbin type friction stir welding tool 20. The materials to be joined are friction stir welded while being sandwiched between the upper shoulder portion 4 and the lower shoulder portion 12. The gap between the upper shoulder portion 4 of the upper rotating body 1 and the lower shoulder portion 12 of the lower rotating body 10 is preferably shorter by about 0.1 to 0.3 mm than the thickness of the material to be joined. By being sandwiched by a gap smaller than the thickness of the material to be joined, stress necessary for friction stir welding is applied to the material to be joined. Further, since the stress is canceled out inside the bobbin type friction stir welding tool 20, rigidity and the like required for the friction stir welding apparatus can be reduced.

The diameter of the stirring shaft 14 is slightly smaller than the inner diameter of the upper shoulder portion 4 so that the stirring shaft 14 can smoothly rotate inside the upper shoulder portion 4 and is softened from the gap between the stirring shaft 14 and the upper shoulder portion 4. It is preferable to prevent the material from entering.

As materials for the upper rotating body 1 and the lower rotating body 10, various conventionally known metal materials, cemented carbides, ceramic materials, and the like can be used as long as the effects of the present invention are not impaired. In consideration of the above, it is preferable to use hot tool steel such as SKD61. In addition, it is not necessary to make all the parts the same raw material, For example, it is good also considering only the surface which touches the to-be-joined material of the upper rotary body 1 and / or the lower rotary body 10 as a ceramic material.

8 and 9 are a side view and a plan view showing another example of the upper rotating body used in the friction stir welding apparatus according to the embodiment of the present invention. In the upper rotating body 100, the upper shoulder portion 4 has a convex portion 5, and is attached to the bottom surface of the spindle so that the convex portion 5 faces downward (in a direction facing the lower rotating body).

10 and 11 are a side view and a plan view showing another example of the lower rotating body used in the friction stir welding apparatus according to the embodiment of the present invention. In the lower rotating body 200, the lower shoulder portion 12 has a recess 13. Here, the alternate long and short dash line in FIG. 10 indicates that the probe portion 16 is connected to the bottom surface of the recess 13.

At the time of friction stir welding, the material to be joined is agitated in a state in which the convex portion 5 is inserted into the concave portion 13, and the material to be joined passes through the gap between the convex portion 5 and the concave portion 13, thereby causing various directions. The complicated flow which arises can arise and the orientation of the crystal | crystallization in a stirring part can be reduced. In addition, what is necessary is just to set suitably the insertion amount of the convex part 5 with respect to the recessed part 13 in the range which does not impair the effect of this invention.

In the friction stir welding apparatus according to the present invention, the concave portion 13 is provided in the upper shoulder portion 4, the convex portion 5 is provided in the lower shoulder portion 12, and the convex portion 5 of the lower shoulder portion 12 is inserted into the concave portion 13 of the upper shoulder portion 4. Friction stir welding may be performed in such a manner.

(B) Friction stir welding apparatus main body FIGS. 12 and 13 are a schematic side view and a schematic front view, respectively, of a friction stir welding apparatus according to an embodiment of the present invention (a preheating mechanism is not shown). The friction stir welding apparatus 30 includes an upper rotating body motor 32 and an upper rotating body spindle 34 for rotating the upper rotating body 1, a lower rotating body motor 36 and a lower rotating body spindle 38 for rotating the lower rotating body 10, A sample fixing base 40 for fixing the bonding material, a sample fixing base moving motor 42 for moving the sample fixing base 40, and a sample fixing base base 44 are provided. Here, the sample fixing table 40, the sample fixing table moving motor 42, and the sample fixing table 44 are not indispensable constituent elements, and are a structure having a sufficient weight or a plate material fixed by an arbitrary method, etc. The treatment can also be performed using the friction stir welding apparatus 30 that does not include the sample fixing table 40, the sample fixing table moving motor 42, and the sample fixing table 44.

Since the friction stir welding apparatus 30 uses the bobbin type friction stir welding tool 20 in which the upper rotating body 1 and the lower rotating body 10 are separately driven, two motors (an upper rotating body motor 32 and a lower rotating body motor 32) are used. 36) It is necessary to use a double-acting type. Here, for example, when the purpose is to join an aluminum plate having a thickness of about 2 mm, it is preferable to use a motor having an output of 0.73 kW or more and a rotation speed of 1000 rpm or more. In consideration of using the friction stir welding apparatus 30 at a household outlet, the motor output is more preferably about 0.73 kW or less.

In the friction stir welding apparatus 30, it is preferable that the upper rotating body motor 32 and the lower rotating body motor 36 can set rotation independently. If the rotation direction of the upper rotary body motor 32 and the rotation direction of the lower rotary body motor 36 are designed to be reversed, it is not always possible to switch the rotation direction. Therefore, it is preferable that the rotation direction can be arbitrarily set in each motor.

The upper rotating body 1 is connected to the upper rotating body spindle 34, and the lower rotating body 10 is connected to the lower rotating body spindle 38, respectively. Further, the material to be joined 48 is fixed to the sample fixing base 40, and the region to be joined or reformed is press-fitted between the rotating upper rotating body 1 and the lower rotating body 10 and moved so that the joining or reforming can be performed. To achieve.

By rotating the upper rotating body 1 and the lower rotating body 10 of the bobbin type friction stir welding tool in opposite directions and performing the friction stir welding, the tool torque can be offset, and the lateral vibration of the tool during the friction stir welding Can be suppressed. Furthermore, the tool torque can be changed depending on the combination of the rotational speeds of the upper rotating body 1 and the lower rotating body 10, and a joining condition that minimizes the tool torque can be selected.

Further, by designing the friction stir welding apparatus 30 to apply a tension / compression load rather than a bending load, even a small friction stir welding apparatus 30 can obtain sufficient rigidity. Furthermore, by using a collet chuck to fix the stirring shaft 14, the positional accuracy of the bobbin type friction stir welding tool 20 can be ensured.

The upper rotating body spindle 34 can be coaxial with the lower rotating body spindle 38 by a timing belt. Here, in order not to decelerate the rotation, the timing belt pulley 46 may have the same diameter on the motor side and the tool side. Further, by attaching a collet chuck to the lower rotating body spindle 38, the bobbin type friction stir welding tool 20 can be fixed without causing misalignment even when the stirring shaft 14 is thin.

As described above, the sample fixing base 40, the sample fixing base moving motor 42, and the sample fixing base 44 are not essential components of the friction stir welding apparatus 30, but are incorporated into the friction stir welding apparatus 30 as necessary. Is preferred. For example, a brushless DC motor can be used as the sample fixing table moving motor 42, and the sample fixing table 40 can be linearly moved by transmitting the rotational movement of the motor to a trapezoidal screw via a spur gear. In this case, the allowable thrust of the trapezoidal screw may be appropriately determined depending on the material to be joined. In addition, the maximum linear moving speed of the sample fixing base 40 is preferably set to 300 mm / min or more from the viewpoint of the degree of freedom in setting the joining conditions.

In the friction stir welding apparatus 30, since the bobbin type friction stir welding tool 20 is used for joining and modification, the sample fixing base 40 fixes the end of the material to be joined with a holding jig or the like, It is necessary to design so that the bobbin type friction stir welding tool 20 does not interfere. Here, since the back plate (a metal plate placed under the material to be joined) used in the case of normal friction stir welding is unnecessary, the friction stir welding apparatus 30 has the sample fixing base 40. Even so, it can be made relatively light.

By using a friction stir welding apparatus 30 having a preheating mechanism described later, a force (Fx) in the joining direction applied to the bobbin type friction stir welding tool 20 at the time of friction stir welding, a lateral force orthogonal to the joining line Both (Fy) and the force (Fz) in the vertical direction perpendicular to the joining line can be 10 kgf or less.

In the friction stir welding apparatus 30, it is preferable to manually control the traveling direction of the bobbin type friction stir welding tool 20. At this time, the position of the bobbin type friction stir welding tool 20 may be determined by manually moving the friction stir welding apparatus 30, and the relative bobbin type friction stirrer may be determined by manually moving the workpiece 48. The position of the welding tool 20 may be determined. In addition, by using the friction stir welding apparatus 30, the fixation of the material to be joined 48 at the time of friction stir welding can be relaxed. For example, the friction stir welding is performed even when only one point of the material to be joined 48 is fixed. Can do.

(C) Preheating mechanism The friction stir welding apparatus 30 of the present invention has a preheating mechanism. As the preheating mechanism, various conventionally known preheating mechanisms can be used as long as the effects of the present invention are not impaired. A mechanism using current heating, a mechanism using laser irradiation, a mechanism using high-frequency heating, a micro arc Although a mechanism using hot air, a mechanism using hot air, a mechanism using frictional heat, and the like can be exemplified, it is preferable to use a mechanism using current heating from the viewpoint of cost, apparatus weight, and the like.

Here, when laser irradiation is used as the preheating mechanism, the absorption efficiency of the laser is increased by melting the material to be joined. In other words, the material to be bonded can be preheated more efficiently in the depth direction and the width direction by melting the material to be bonded by laser irradiation.

FIG. 14 is a conceptual diagram of a preheating mechanism using current heating that can be suitably used in the friction stir welding apparatus according to an embodiment of the present invention. The preheating mechanism 50 has a positive electrode 52 and a negative electrode 54, and the positive electrode 52 and the negative electrode 54 are each connected to a power source 56. Here, when the positive electrode 52 and the negative electrode 54 are brought into contact with the material to be bonded 48 and a voltage is applied, the material to be bonded 48 is energized, and the material to be bonded 48 is heated by resistance heat generation.

The heating region of the material to be bonded 48 can be controlled by the interval between the positive electrode 52 and the negative electrode 54. The interval is not particularly limited, but in order to reduce the plastic deformation resistance of the material to be bonded 48 by local heating and efficiently reduce the process load at the time of friction stir welding, the interval is set to the diameter of the probe portion 16. The diameter of the upper shoulder portion 4 or the lower shoulder portion 12 is preferably used. Further, in order to efficiently guide the traveling direction of the bobbin type friction stir welding tool 20, it is preferable that the distance be approximately equal to the diameter of the probe portion 16. In addition, the temperature of 48 of a to-be-joined material can be raised efficiently by arranging the positive electrode 52 and the negative electrode 54 in a joining direction.

The preheating mechanism 50 can be disposed at various positions within a range not impairing the effects of the present invention, and may be provided separately from the friction stir welding apparatus 30, but is preferably incorporated in the friction stir welding apparatus 30. Here, it is preferable that the preheating mechanism 50 is disposed in front of the traveling direction of the bobbin type friction stir welding tool 20, and the traveling direction of the bobbin type friction stir welding tool 20 is induced by softening of the material 48 to be joined by preheating. Note that the preheating is not necessarily performed on the surface of the material to be bonded 48 but may be performed on the back surface of the material to be bonded 48.

It is preferable to raise the temperature of the material to be joined 48 to such an extent that the deformation resistance is sufficiently lowered by the preheating mechanism 50. Here, in the case of an aluminum alloy, the preheating temperature is preferably set to 150 to 250 ° C., because the deformation resistance is greatly reduced at around 200 ° C. regardless of the type. If the preheating temperature is set higher than necessary, the region where the deformation resistance is lowered becomes too wide, and it becomes difficult to guide the traveling direction of the bobbin type friction stir welding tool 20.

In addition, by forcibly cooling the periphery of the region heated by the preheating mechanism 50, the difference in deformation resistance of the material to be bonded 48 in the heating region and the vicinity thereof increases, and the traveling direction of the bobbin type friction stir welding tool 20 is changed. It can be guided more efficiently. Here, various types of conventionally known cooling methods can be used for forced cooling within a range that does not impair the effects of the present invention. For example, liquid nitrogen, liquid CO ₂ , inert gas, air, water, etc. can be used with a nozzle or the like. This can be achieved by spraying.

(2) Friction stir welding method The friction stir welding method of the present invention comprises a bobbin type friction stir welding tool having an upper rotating body, a lower rotating body, and a stirring shaft formed integrally with the lower rotating body. A step of sandwiching a material to be joined between the upper rotating body and the lower rotating body, a step of rotating the upper rotating body and the lower rotating body in opposite directions, and a step of moving the bobbin type friction stir welding tool. And a preheating mechanism is disposed in front of the bobbin type friction stir welding tool in the advancing direction, and the bobbin type friction stir welding tool is guided in the advancing direction by softening the material to be joined by the preheating. It is what.

By rotating the upper rotating body and lower rotating body of the bobbin type friction stir welding tool in opposite directions and performing friction stir welding, the tool torque can be offset and the lateral vibration of the tool during friction stir welding is suppressed. can do. Furthermore, the tool torque can be changed by a combination of the rotational speeds of the upper rotating body and the lower rotating body, and the joining conditions that minimize the tool torque can be selected.

In the friction stir welding method of the present invention, a preheating mechanism is disposed in front of the traveling direction of the bobbin type friction stir welding tool, and the traveling direction of the bobbin type friction stir welding tool is induced by softening the material to be joined by preheating. Here, from the viewpoint of sufficiently softening the material to be joined by preheating, the thickness of the material to be joined is preferably 5 mm or less.

Also, it is preferable to manually control the traveling direction of the bobbin type friction stir welding tool, and the material to be joined is preferably aluminum or an aluminum alloy. Here, in order to suppress breakage of the stirring shaft during bonding, for example, when the material to be bonded is aluminum or an aluminum alloy, the thickness of the material to be bonded is preferably 5 mm or less.

The representative embodiments of the friction stir welding apparatus and the friction stir welding method according to the present invention have been described above, but the present invention is not limited to these embodiments, and various design changes are possible. Are all included in the technical scope of the present invention.

FIG. 15 shows an appearance photograph of the friction stir welding apparatus manufactured as an example. A TEKNOMOTOR three-phase induction motor with an output of 0.73 kW was used for the upper rotating body motor and the lower rotating body motor, and an inverter (V1000) manufactured by Yaskawa Electric was used as the motor control device. As is clear from comparison with a plastic bottle taken as a reference, the friction stir welding apparatus produced is extremely small (width 280 mm × depth 440 mm × height 570 mm).

Above the friction stir welding apparatus, a motor for the upper rotating body and a motor for the lower rotating body are installed in parallel and are coaxial with the timing belt. A feed motor for moving the base material is attached to the sample fixing base. The maximum tool rotation speed of this apparatus was 1200 rpm, the maximum joining speed was 300 min / mm, and the specifications were such that materials up to a plate thickness of 2 mm could be joined.

FIG. 16 shows a photograph of the appearance of the bobbin type friction stir welding tool (upper rotating body and lower rotating body) produced in the example. The material of the tool is hot tool steel (SKD61), and the upper tool is fixed to the lower surface of the spindle part through screws in four mounting holes. In addition, the lower tool has a gripped part and is fixed with a collet chuck.

The surface of the upper shoulder portion and the lower shoulder portion that are in contact with the material to be joined has a 10 ° dent angle to minimize burrs, and the diameter is 10 mm. The diameter of the probe part was about 4 mm.

[Process load measurement]
Using the friction stir welding apparatus, friction stir welding was performed on an A1050 plate (90 mm × 100 mm × 2 mm) having a thickness of 2 mm, and various process loads during the bonding were measured. FIG. 17 is a load cell layout diagram for measuring the process load during friction stir welding. The force Fx in the joining direction was measured with the load cell X (rated load: 5000 N), and the component force of the force Fy in the direction orthogonal to the joining line was measured with the load cells Y1 to Y4 (rated load: 300 N). The strain applied to the load cell was converted into an electric signal by a load cell amplifier, and the acquired electric signal was recorded on a PC.

FIG. 18 shows Fx when the rotation directions of the upper and lower rotating bodies are both CW, the rotation speeds are 600 rpm and 1000 rpm, and the movement speed is 50 to 300 min / mm. Fx shows a small value under the condition that the rotational speed of the tool is high and the moving speed is low, and is about 70 N at 1000 rpm and 50 min / mm.

FIG. 19 shows the result of measuring Fy when the rotation directions of the upper and lower rotating bodies are the same (CW) and different (upper tool CCW / lower tool CW). When the rotation direction is the same, both the upper and lower rotating bodies are set to 700 rpm, and when the tool rotating direction is different, the upper rotating body is set to 600 rpm and the lower rotating body is set to 700 rpm.

Focusing on the absolute value of Fy, the value is generally smaller in the case of reverse rotation than in the case of the same rotation. This is a result of canceling out the forces generated by the upper and lower rotating bodies. In addition, as shown in FIG. 20, in the case of the same rotation, a force that pushes the bonded material in one direction is applied, whereas in the reverse rotation, the bonded material rotates in the CCW direction. Force is applied.

FIG. 21 shows the result of measuring Fy when the rotational speed of the lower rotating body is fixed at 700 rpm and the rotational speed of the upper rotating body is changed from 400 to 600 rpm when the rotational direction is reverse. . As the rotational speed of the upper rotating body decreases, Fy tends to decrease. At 400 rpm, the values of Fy1 and Fy2 are almost zero. The preferred combination of the rotational speeds of the upper and lower rotating bodies can change under various conditions, but the force applied from the upper and lower rotating bodies can be balanced by independently adjusting the rotational speed of the upper and lower rotating bodies. I understand.

[Preheating]
A simple preheating mechanism using an energization heating method in which a nichrome electrode having a sharp tip is brought into contact with the surface of the material to be joined (distance between electrodes: 4 mm) and the electrodes are energized was produced. FIG. 22 shows the temperature change of the back surface of the A1050 plate when the set current is 100 A and the nichrome electrode is brought into contact with the A1050 plate having a thickness of 2 mm and moved at 200 min / mm. The maximum temperature reached is about 150 ° C., and the temperature is expected to be even higher on the surface of the A1050 plate. Therefore, it is considered that this will contribute sufficiently to the reduction of the plastic deformation resistance of A1050.

FIG. 23 shows measured values of various process loads during friction stir welding with and without preheating. The nichrome electrode was placed 8.5 mm forward from the center of the bobbin type friction stir welding tool, and preheating was performed by moving with the tool (setting current: 100 A). The friction stir welding conditions were such that the upper and lower rotating bodies were reversely rotated (upper tool CCW / lower tool CW), the moving speed was 200 min / mm, the rotating speed was 600 rpm on the upper side, and 700 rpm on the lower side.

The decrease in process load due to preheating is remarkable, and Fy is several N except for Fy2. In addition, Fx is also reduced by about 30% by preheating, and both Fy and Fx are values that allow manual control of the tool position.

FIG. 24 is an appearance photograph of the sample obtained by friction stir welding with preheating. The appearance of the joined body obtained using the prototyped small friction stir welding apparatus is good, and no particular change is observed even with preheating. Although there are defects peculiar to the case where a bobbin type tool is used at the start end of the joining, there are few burrs, and the surface of the stirring part has a smooth shape.

1,100 ... upper rotating body,
2 ... Tool mounting part,
4 ... Upper shoulder,
5 ... convex part,
6 ... mounting holes,
10, 200 ... lower rotating body,
12 ... Lower shoulder,
13 ... concave portion,
14 ... stirring shaft,
16: Probe part,
20 ... Bobbin type friction stir welding tool,
30 ... friction stir welding apparatus,
32... Motor for upper rotating body,
34 ... Spindle for upper rotating body,
36... Motor for lower rotating body,
38 ... Spindle for lower rotating body,
40: Sample fixing table,
42 ... Motor for moving the sample fixing table,
44... Sample fixing base,
46 ... pulley for timing belt,
48 ... materials to be joined,
50 ... Preheating mechanism,
62 ... Positive electrode,
64 ... negative electrode,
66: Power supply.

Claims

An upper rotating body, a lower rotating body, and a stirring shaft formed integrally with the lower rotating body, and a friction stir welding is performed by sandwiching a material to be joined between the upper rotating body and the lower rotating body. Using the bobbin type friction stir welding tool to perform,
Providing a preheating mechanism for preheating the materials to be joined;
A friction stir welding apparatus characterized by the above.
The rotational speed of the upper rotating body and the lower rotating body can be set independently,
The rotational direction of the upper rotating body and the lower rotating body can be reversed,
The friction stir welding apparatus according to claim 1.
The preheating mechanism is disposed in the forward direction of the bobbin type friction stir welding tool,
Inducing the direction of travel of the bobbin type friction stir welding tool by softening the material to be joined by the preheating,
The friction stir welding apparatus according to claim 1 or 2, characterized in that:
The preheating mechanism is an electric heating system;
The friction stir welding apparatus according to any one of claims 1 to 3, wherein:
The upper rotating body has a convex shape;
The lower rotating body has a concave shape;
The convex portion of the upper rotating body is inserted into the concave portion of the lower rotating body,
The friction stir welding apparatus according to any one of claims 1 to 4, wherein:
The upper rotating body has a concave shape;
The lower rotating body has a convex shape;
The convex portion of the lower rotating body is inserted into the concave portion of the upper rotating body,
The friction stir welding apparatus according to any one of claims 1 to 4, wherein:
Force (Fx) in the joining direction applied to the bobbin type friction stir welding tool during friction stir welding, lateral force (Fy) perpendicular to the joining line, and vertical force (Fz) perpendicular to the joining line Are all 10 kgf or less,
The friction stir welding apparatus according to any one of claims 1 to 6, wherein:
Manually controlling the direction of travel of the bobbin type friction stir welding tool during friction stir welding;
The friction stir welding apparatus according to any one of claims 1 to 7, wherein:
Using a bobbin type friction stir welding tool having an upper rotating body, a lower rotating body, and a stirring shaft formed integrally with the lower rotating body,
Sandwiching the material to be joined between the upper rotating body and the lower rotating body;
Rotating the upper rotating body and the lower rotating body in opposite directions;
Moving the bobbin-type friction stir welding tool,
A preheating mechanism is disposed in front of the bobbin type friction stir welding tool in the traveling direction,
Inducing the direction of travel of the bobbin type friction stir welding tool by softening the material to be joined by the preheating,
A friction stir welding method characterized by the above.
Manually controlling the direction of travel of the bobbin type friction stir welding tool,
The friction stir welding method according to claim 9.
The material to be joined is aluminum or an aluminum alloy;
The friction stir welding method according to claim 9 or 10.