JP7479910B2 - Friction stir welding attachment, friction stir welding head, friction stir welding device, and friction stir welding method - Google Patents

Description

The present invention relates to a friction stir welding attachment, a friction stir welding head, a friction stir welding device, and a friction stir welding method.

Friction stir welding is used as a method for joining materials.
In friction stir welding, in order to obtain sufficient frictional heat, a high torque is required for rotating the welding tool, and thus a dedicated friction stir welding device has been used in the past. On the other hand, a general-purpose machine tool can be used as the friction stir welding device if it can obtain a high torque (see Patent Document 1).
In Patent Document 1, in order to prevent overflow of the fluidized portion during friction stir welding, the welding tool is raised and lowered by position control of a machine tool.

JP 2017-127881 A

In the above-mentioned friction stir welding, frictional heat is generated in the workpiece by the rotation of the welding tool. In contrast, by raising and lowering the welding tool at high speed, frictional heat is obtained by reciprocating movement in addition to the frictional heat generated by the rotation of the workpiece, which may contribute to improving the friction stir welding performance.
However, in the above-mentioned Patent Document 1, the joining tool is raised and lowered by controlling the position of the machine tool, and the speed is about several Hz to several tens of Hz, which is not high enough to generate frictional heat.

The object of the present invention is to provide a friction stir welding attachment, a friction stir welding head, a friction stir welding device, and a friction stir welding method that can generate friction heat due to reciprocating movement in addition to friction heat due to rotation.

The friction stir welding attachment of the present invention is characterized by having a rotating part mounted on the spindle of a machine tool, a fixed part connected to the spindle head of the machine tool, a reciprocating part supported by the fixed part and capable of reciprocating in the axial direction of the spindle and restricted in rotation around the axis of the spindle, a processing shaft supported rotatably on the reciprocating part and capable of mounting a welding tool at its tip, a rotation drive part that drives the processing shaft to rotate, and a cam mechanism that connects the rotating part and the reciprocating part and causes the reciprocating part to reciprocate when the rotating part rotates relative to the reciprocating part.

In the present invention, the rotary drive unit rotates the processing shaft, and the workpieces can be friction-stir-welded by rotating the welding tool. Meanwhile, the main shaft rotates the rotating part, and the cam mechanism reciprocates the reciprocating part, so that the welding tool in contact with the workpieces can be reciprocated. The speed of the reciprocating movement of the welding tool corresponds to the rotation speed of the main shaft, for example, if the cam mechanism reciprocates once per rotation, and can be several hundred Hz to several thousand Hz. Therefore, sufficient frictional heat can be generated by the reciprocating movement of the welding tool, and the friction stir welding of the workpieces can be performed with a sufficient amount of heat.
As a result, it is possible to provide a friction stir welding attachment that can generate frictional heat due to reciprocating movement in addition to frictional heat due to rotation.

In the friction stir welding attachment of the present invention, it is preferable that the cam mechanism comprises a cam member arranged coaxially on either the rotating part or the reciprocating part and having a cam surface that intersects with the axial direction of the main shaft, a cam follower installed on the other of the rotating part or the reciprocating part and sliding or rolling on the cam surface, and a pressing member that presses the cam follower against the cam surface.
In this invention, when the rotating part rotates relative to the reciprocating part, the cam follower slides or rolls on the cam surface, thereby enabling the reciprocating part to move back and forth in the axial direction of the main shaft efficiently with a simple structure.

In the friction stir welding attachment of the present invention, it is preferable that the cam mechanism has a plurality of the cam followers arranged point-symmetrically about the axis of the spindle.
In the present invention, the pressure force applied by the pressing member from the cam follower to the cam surface is point symmetrical about the axis of the spindle, that is, uniform in the circumferential direction, so that it is possible to prevent the reciprocating part or the welding tool from tilting due to the influence of such pressing force.

In the friction stir welding attachment of the present invention, the rotation drive unit is preferably an air motor that is rotated by air supplied through an axis of the main spindle.
In the present invention, the power source for the rotary drive unit can be easily secured. Also, there is no need for power piping or wiring to be connected to the reciprocating unit from the outside, and the peripheral structure can be simplified.
The rotary drive unit may be an electric motor that receives power from the spindle head via a fixed unit.

In the friction stir welding attachment of the present invention, it is preferable that the air motor is installed in the rotating portion and connected to the processing shaft via a rotation transmission mechanism that is axially displaceable.
In the present invention, the air motor can be installed close to the spindle, and the air supply line from the spindle can be simplified. On the other hand, since the air motor and the rotary shaft are connected via a rotation transmission mechanism that can be displaced in the axial direction, even when the machining shaft reciprocates together with the reciprocating part, the reciprocating motion is not transmitted to the air motor.
The air motor may be installed in the reciprocating section. In this case, the rotation transmission mechanism that can be displaced in the axial direction can be omitted. However, it is necessary to allow the air from the main shaft to move back and forth along the path that receives the air from the spindle in the rotating section and then guides it to the reciprocating section.

A friction stir welding head according to the present invention is characterized by comprising the above-mentioned friction stir welding attachment according to the present invention, and the welding tool mounted on the friction stir welding attachment.
In the present invention, the same effects as those of the above-mentioned friction stir welding attachment of the present invention can be obtained.

The friction stir welding apparatus of the present invention is characterized by having the friction stir welding attachment of the present invention described above, the welding tool attached to the friction stir welding attachment, and a machine tool to which the friction stir welding attachment is attached.
In the present invention, the tool is rotated by the rotary drive unit to perform friction stir welding on the workpiece, and the tool is moved back and forth along the axis of the spindle by rotating the spindle, thereby increasing friction between the tool and the workpiece and promoting friction stir welding.

The friction stir welding method of the present invention is characterized in that it uses the friction stir welding apparatus of the present invention described above, rotates the welding tool with the rotary drive unit to perform friction stir welding on the workpiece, and moves the welding tool back and forth in the axial direction of the spindle by rotating the spindle.
In the present invention, the tool rotates around the axis of the spindle while moving back and forth along the axis of the spindle, thereby increasing the friction between the tool and the workpiece and promoting friction stir welding.

The present invention provides a friction stir welding attachment, a friction stir welding head, a friction stir welding device, and a friction stir welding method that can generate friction heat from reciprocating movement in addition to friction heat from rotation.

1 is a perspective view showing a friction stir welding apparatus according to an embodiment of the present invention; FIG. 2 is a cross-sectional view showing the friction stir welding attachment according to the embodiment. FIG. 4 is a development view showing a cam profile according to the embodiment. 5A to 5C are cross-sectional views showing the operation of the welding tool of the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, a friction stir welding apparatus 1 of this embodiment is configured by mounting a friction stir welding attachment 10 based on the present invention and a general-purpose welding tool 20 for friction stir welding on a general-purpose machine tool 2 having a vertical spindle.

The machine tool 2 includes a table 3 on which a workpiece 9 is fixed, a spindle 4 to the tip of which a tool can be attached, a spindle head 5 that supports the spindle 4 so that it can rotate freely, and a moving mechanism 6 that moves the spindle head 5 to any position.
The movement mechanism 6 has a slider 62 supported by a horizontal guide bar 61, and the spindle head 5 is supported facing downward by the slider 62. Therefore, by raising and lowering the spindle head 5 relative to the slider 62, the tip of the spindle 4 can be moved to a specified position in the Z-axis direction. Also, by moving the slider 62 along the guide bar 61, the tip of the spindle 4 can be moved to a specified position in the X-axis direction.

The spindle 4 has an axis R that is vertical (Z-axis direction), and can be rotated around the axis R (C-axis direction) by a drive motor in the spindle head 5 and can be stopped at a specified angular position.
The table 3 can be rotated around a vertical axis (C-axis direction) by a drive mechanism installed on the bed 7, and can be stopped at a specified angular position.
The table 3, the spindle 4, the spindle head 5 and the moving mechanism 6 are all mounted on the upper surface of a bed 7, and the whole can be enclosed by a cover 8 which can be opened and closed freely.

A welding tool 20 is attached to the spindle 4 via a friction stir welding attachment 10 based on the present invention. Here, by attaching the welding tool 20 to the friction stir welding attachment 10, the friction stir welding head 19 of the present invention is formed.

In Figure 2, the friction stir welding attachment 10 has a rotating part 11 mounted on the spindle 4 of the machine tool 2, a fixed part 12 connected to a slider 62 (spindle head 5) of the machine tool 2, and a reciprocating part 13 supported by the fixed part 12 and capable of reciprocating in the direction of the axis R of the spindle 4 but restricted in rotation around the axis R of the spindle 4.
Furthermore, the friction stir welding attachment 10 has a processing shaft 14 that is rotatably supported on the reciprocating portion 13 and can have a welding tool 20 attached to its tip, a rotational drive portion 15 that rotates and drives the processing shaft 14, and a cam mechanism 16 that connects the rotating portion 11 and the reciprocating portion 13 and causes the reciprocating portion 13 to move back and forth when the rotating portion 11 rotates relative to the reciprocating portion 13.

The rotating part 11 can be attached to the main shaft 4 by a standard-based tapered shank 111 and has a center through hole 112 along the axis, through which center through air can be supplied from the main shaft 4 .
The fixed part 12 is attached to the outer periphery of the end of the rotating part 11 opposite the tapered shank 111 , and the two are rotatable relative to each other via a bearing 121 .

A sub-shank 122 is formed on the fixed part 12 at a portion that protrudes outward, and the sub-shank 122 can be fitted into a receiving portion of the spindle head 5 when the rotating part 11 is attached to the spindle 4. Therefore, by attaching the rotating part 11 to the spindle 4, the fixed part 12 is connected to the spindle head 5 and prevented from rotating, and the rotating part 11 and the spindle 4 can rotate integrally with the fixed part 12 and the spindle head 5.
A cylindrical guide sleeve 123 is formed on the end of the fixed part 12 opposite to the main shaft 4 , and the guide sleeve 123 holds the reciprocating part 13 .

The reciprocating portion 13 is a cylindrical member, and is capable of reciprocating along the axis R of the main shaft 4 inside the guide sleeve 123. Between the inner peripheral surface of the guide sleeve 123 and the outer peripheral surface of the reciprocating portion 13, a coating of a low-friction material is formed to enhance slidability.
A rotation restriction mechanism 131 using a ball spline or the like is formed between the reciprocating portion 13 and the guide sleeve 123, and the rotation of the reciprocating portion 13 and the guide sleeve 123 around the axis R is restricted.

A processing shaft 14 is provided at the axis of the reciprocating portion 13 .
The machining shaft 14 is rotatably supported by the reciprocating portion 13 via a bearing 141. The bearing 141 is restricted in displacement in the direction of the axis R, and the machining shaft 14 is capable of reciprocating in the direction of the axis R following the reciprocating portion 13.
One end (the lower end in the figure) of the processing shaft 14 is exposed from the end face of the reciprocating portion 13, and a joining tool 20 is attached to the tip thereof.

The other end (the upper end in the figure) of the processing shaft 14 is connected to a rotation drive unit 15 .
The rotary drive unit 15 has an air motor 151 housed in the rotating unit 11 and a joint 152 that connects the shaft of the air motor 151 to the processing shaft 14 .
The air motor 151 is connected to the center through hole 112 of the rotating portion 11, and is rotatable by receiving center through air supplied from the main shaft 4 through the center through hole 112.
The joint 152 is a rotation transmission mechanism formed using a ball spline or the like and capable of being displaced in the axial direction, and is capable of absorbing axial displacement between the processing shaft 14 and the air motor 151 while transmitting the rotational force from the air motor 151 to the processing shaft 14. As a result, even when the processing shaft 14 reciprocates together with the reciprocating section 13, the reciprocating movement is not transmitted to the air motor 151.

The cam mechanism 16 has an annular cam member 161 attached to the rotating portion 11, and a cam surface 162 is formed on the reciprocating portion 13 side.
A rolling type cam follower 163 using a roller is provided on the reciprocating part 13, and a pressing member 164 such as a compression spring is provided between the reciprocating part 13 and the guide sleeve 123 of the fixed part 12. Therefore, the pressing member 164 urges the reciprocating part 13 toward the rotating part 11, and the cam follower 163 is constantly pressed against the cam surface 162.

As shown in FIG. 3, the cam surface 162 has a sinusoidal cam profile of one period per revolution, and when the rotating part 11 rotates once relative to the reciprocating part 13, the reciprocating part 13 moves back and forth once relative to the rotating part 11.
In this embodiment, the cam mechanism 16 has a total of four cam followers 163 that are evenly arranged in the circumferential direction, and a pair of rotation control mechanisms 131 between the reciprocating portion 13 and the guide sleeve 123 are arranged opposite each other in the diametric direction, and each is formed point-symmetrically with respect to the axis R.

In this embodiment, friction stir welding is carried out as follows.
First, two members to be friction stir welded as the workpieces 9 are fixed to the table 3 in a state where they are butted against each other via a weld line.
Next, a welding tool 20 is attached to the tip of the processing shaft 14 of the friction stir welding attachment 10 to form a friction stir welding head 19, and this friction stir welding head 19 is attached to the spindle 4 by a tool changer or the like. By this attachment operation, the rotating part 11 is connected to the spindle 4, and the fixed part 12 is connected to the spindle head 5.

When the workpiece 9 and the friction stir welding head 19 are prepared, the moving mechanism 6 moves the welding tool 20 close to the welding line of the workpiece 9, and friction stir welding is started.
That is, when center-through air is supplied from the main spindle 4 , the processing shaft 14 and the welding tool 20 are rotationally driven by the rotary drive unit 15 , and frictional heat is generated between the workpiece 9 and the welding tool 20 due to the rotation of the welding tool 20 .
Furthermore, by rotating the main shaft 4, the reciprocating portion 13 and the processing shaft 14 are driven to reciprocate via the cam mechanism 16, and frictional heat is generated between the workpiece 9 and the welding tool 20 due to the reciprocating movement of the welding tool 20.

4, in normal friction stir welding, when the welding tool 20 is moved downward in the figure along the axis R while being rotated about the axis R, the tip pin 21 of the welding tool 20 is pressed into the weld line portion of the workpiece 9. At this time, frictional heat is generated between the peripheral surface 22 of the tip pin 21 and the workpiece 9, and a softened or melted softened portion 91 is formed in the workpiece 9.
In this state, by moving the joining tool 20 along the joining line on the surface of the workpiece 9, a new softened portion 91 is formed on the front side of the tip pin 21 in the direction of movement (right side in the figure), and a re-solidified portion 92 is formed on the rear side of the direction of movement (left side in the figure), thereby performing friction stir welding of the two parts butted together at the joining line.
Furthermore, in this embodiment, in addition to friction caused by the rotation of the welding tool 20, frictional heat caused by the reciprocating movement of the welding tool 20 along the direction of the axis R is generated on the peripheral surface 22 of the tip pin 21. The reciprocating movement of the welding tool 20 can be performed at a speed of several hundred Hz to several thousand Hz based on the rotation speed of the main shaft 4, and sufficient frictional heat can be obtained to supplement the frictional heat caused by the rotation, thereby facilitating friction stir welding.

In this embodiment, the workpiece 9 can be friction-stir-welded by rotating the welding tool 20 by rotating the processing shaft 14 with the rotary drive unit 15. Meanwhile, the welding tool 20 in contact with the workpiece 9 can be reciprocated by rotating the rotating unit 11 with the spindle 4 and reciprocating the reciprocating unit 13 with the cam mechanism 16. The speed of the reciprocating movement of the welding tool 20 corresponds to the rotational speed of the spindle 4 if the cam mechanism 16 reciprocates once per rotation, and can be several hundred Hz to several thousand Hz. Therefore, sufficient frictional heat can be generated by the reciprocating movement of the welding tool 20, and the friction stir welding of the workpiece 9 can be performed with a sufficient amount of heat.
As a result, it is possible to provide a friction stir welding attachment 10 or a friction stir welding head 19 that can generate friction heat due to reciprocating movement in addition to friction heat due to rotation.

In this embodiment, a cam mechanism 16 is used to move the reciprocating part 13 back and forth. In particular, by using the cam surface 162, the cam follower 163, and the pressing member 164, when the rotating part 11 rotates relative to the reciprocating part 13, the cam follower 163 can be made to roll smoothly on the cam surface 162, and the reciprocating part 13 can be efficiently moved back and forth in the direction of the axis R of the main shaft 4 with a simple structure.

In this embodiment, the cam mechanism 16 has multiple cam followers 163 arranged point-symmetrically around the axis R of the spindle 4, and the pressure applied by the pressing member 164 to the cam surface 162 from the cam followers 163 is point-symmetrical around the axis R of the spindle 4, that is, uniform in the circumferential direction, so that it is possible to prevent the reciprocating part 13 or the joining tool 20 from tilting due to the influence of such pressure force.

In this embodiment, the air motor 151 that is rotated by center-through air supplied through the axis of the main shaft 4 is used as the rotation drive unit 15, so it is easy to ensure a power source for the rotation drive unit 15. In addition, there is no need for power piping or wiring to be connected to the reciprocating unit 13 from the outside, and the peripheral structure can be simplified.
In this embodiment, since the air motor 151 is installed in the rotating section 11, the air motor 151 can be installed in a location close to the main shaft 4, and the air supply line from the main shaft 4 can be simplified. Meanwhile, since the air motor 151 and the processing shaft 14 are connected via a joint 152, which is a rotation transmission mechanism that can be displaced in the axial direction, even when the processing shaft 14 reciprocates together with the reciprocating section 13, the reciprocating movement is not transmitted to the air motor 151.

The present invention is not limited to the above-described embodiment, and modifications within the scope of the present invention are included in the present invention.
In the above embodiment, the rotation drive unit 15 is an air motor 151 that is rotated by air supplied through the shaft center of the spindle 4. However, the rotation drive unit 15 may be an electric motor that receives power from the spindle head 5 via the fixed unit 12.
Moreover, the air motor 151 may be installed in the reciprocating section 13. In this case, the joint 152 as a rotation transmission mechanism capable of being displaced in the axial direction can be omitted. However, it is necessary to allow reciprocating movement in the path from the air from the main shaft 4 that is received by the rotating section 11 to the reciprocating section 13.
The cam mechanism 16 is not limited to one that uses a cam surface 162 arranged toward the reciprocating portion 13 and a roller-type cam follower 163, but the cam follower 163 may be of a sliding type, and a cam groove formed on the inner surface of the cam member 161 may be used instead of the cam surface 162.

The present invention can be used in a friction stir welding attachment, a friction stir welding head, a friction stir welding device, and a friction stir welding method.

1...Friction stir welding device, 2...Machine tool, 3...Table, 4...Spindle, 5...Spindle head, 6...Moving mechanism, 61...Guide bar, 62...Slider, 63...Spindle head, 7...Bed, 8...Cover, 9...Workpiece, 10...Friction stir welding attachment, 11...Rotating part, 111...Tapered shank, 112...Center through hole, 12...Fixed part, 121...Bearing, 122...Sub shank, 123...Guide Sleeve, 13... reciprocating part, 131... rotation restriction mechanism, 14... machining shaft, 141... bearing, 15... rotation drive part, 151... air motor, 152... joint, 16... cam mechanism, 161... cam member, 162... cam surface, 163... cam follower, 164... pressing member, 19... friction stir welding head, 20... welding tool, 21... tip pin, 22... peripheral surface, 91... softened part, 92... resolidified part, R... axis of the main shaft.

Claims (7)

A rotating part attached to a spindle of a machine tool;
a fixing portion connected to a spindle head of the machine tool;
a reciprocating part supported by the fixed part and reciprocatable in the axial direction of the spindle and restricted in rotation around the axis of the spindle;
a processing shaft rotatably supported by the reciprocating portion and capable of mounting a joining tool at its tip;
A rotation drive unit that rotates the processing shaft;
a cam mechanism that connects the rotating portion and the reciprocating portion and causes the reciprocating portion to reciprocate when the rotating portion rotates relative to the reciprocating portion ,
The cam mechanism includes:
a cam member arranged coaxially on either the rotating portion or the reciprocating portion and having a cam surface intersecting an axial direction of the main shaft;
a cam follower that is disposed on the other of the rotating portion or the reciprocating portion and slides or rolls on the cam surface;
a pressing member that presses the cam follower against the cam surface . The friction stir welding attachment according to claim 1 ,
A friction stir welding attachment, characterized in that the cam mechanism has a plurality of cam followers arranged point-symmetrically about the axis of the spindle. The friction stir welding attachment according to claim 1 or 2 ,
Friction stir welding attachment, characterized in that the rotation drive unit is an air motor that is rotated by air supplied through an axis of the main shaft. The friction stir welding attachment according to claim 3 ,
The friction stir welding attachment is characterized in that the air motor is installed in the rotating portion and is connected to a processing shaft via a rotation transmission mechanism that is axially displaceable. The friction stir welding attachment according to any one of claims 1 to 4 ,
and the welding tool attached to the friction stir welding attachment. The friction stir welding attachment according to any one of claims 1 to 4 ,
The welding tool attached to the friction stir welding attachment;
and a machine tool to which the friction stir welding attachment is attached. Using the friction stir welding apparatus according to claim 6 ,
The rotation drive unit rotates the welding tool to perform friction stir welding on the workpiece,
A friction stir welding method, comprising: rotating the spindle to reciprocate the welding tool in the axial direction of the spindle.

Images