JP2024057523A - Friction stir welding tools - Google Patents

Abstract

[Problem] To provide a small friction stir welding tool including a rotating jig that can be moved toward and away from workpieces to be welded, and a pin that is inserted into the rotating jig so as to be able to protrude from the shoulder surface of the rotating jig. [Solution] The amount of pin protrusion P of the pin 42 from the shoulder surface 38 of the rotating jig 40 is adjusted by the screw advancement of a feed screw shaft 58 that is rotated by an electric motor 46 housed in a cylindrical main body 44. As a result, compared to a case in which the amount of pin protrusion from the shoulder surface of the rotating jig is adjusted using a hydraulic cylinder, the friction stir welding tool 10 becomes significantly smaller in size because it does not require a hydraulic cylinder, a hydraulic tank that returns hydraulic oil from the hydraulic cylinder, a hydraulic pump that supplies hydraulic oil in the hydraulic tank to the hydraulic cylinder, an electromagnetic control valve that controls the hydraulic oil from the hydraulic pump to the hydraulic cylinder, a seal mechanism that supplies hydraulic pressure to the rotor, etc.

Description

The present invention relates to a friction stir welding device used when joining workpieces by friction stir welding, and in particular to a friction stir welding tool that can change the amount of pin protrusion from the shoulder surface depending on the combination of thicknesses of the workpieces.

When joining workpieces made of the same or dissimilar metals by friction stir welding (FSW), a friction stir welding tool is used that has a shoulder surface that comes into surface contact with the workpieces to generate frictional heat and soften the workpieces, and a pin that protrudes from the center of the shoulder surface and plastically deforms the joint of the workpieces while kneading them to join the atoms of the workpieces, thereby joining the workpieces together. One example is the friction stir welding tool described in Patent Document 1.

This friction stir welding tool is equipped with a rotating jig that is rotated about its axis by the rotation of an electric motor in the actuator and moved upward and downward by a first cylinder in the actuator to move it toward and away from the workpieces to be joined, and a pin that is inserted into the rotating jig so as to be able to protrude downward from the shoulder surface of the rotating jig, and whose upward protruding portion is inserted into the actuator and connected to a second hydraulic cylinder.

JP 2006-000901 A

In the conventional friction stir welding tool described in Patent Document 1, the rotating jig is moved upward and downward by a first cylinder in the actuator, and a pin inserted into the rotating jig can be protruded downward from the shoulder surface of the rotating jig by a second cylinder in the actuator. However, there is no disclosure of the mechanical relationship between the rotating jig and pin, which are rotated by an electric motor in the actuator, and the first and second hydraulic cylinders, and there is an issue in that the feasibility of the friction stir welding tool is unclear.

Even if the above-mentioned friction stir welding tool could be realized, it would require a first hydraulic cylinder and a second hydraulic cylinder, a hydraulic tank for returning hydraulic oil from them, a hydraulic pump for supplying the hydraulic oil in the hydraulic tank to the first hydraulic cylinder and the second hydraulic cylinder, a plurality of electromagnetic control valves for controlling the hydraulic oil from the hydraulic pump to the first hydraulic cylinder and the second hydraulic cylinder, respectively, and a sealing mechanism for supplying hydraulic oil to the rotor, which would result in a large friction stir welding tool.

The present invention was made against the background of the above circumstances, and its purpose is to provide a small friction stir welding tool that includes a rotating jig that can be moved toward and away from the workpieces to be joined, and a pin that is inserted into the rotating jig and can protrude from the shoulder surface of the rotating jig.

The gist of the present invention is a friction stir welding tool comprising: (a) an axially shaped rotating jig that can be moved toward and away from workpieces to be joined; and a pin provided on the rotating jig so as to be capable of protruding from a shoulder surface formed at the tip of the rotating jig; and the tool is held by a tool chuck that is driven to rotate about its axis and moves in the axial direction; (b) a cylindrical main body whose base end is held by the tool chuck and whose tip end is concentrically connected to the rotating jig; (c) an electric motor inserted within the main body so as not to be capable of relative rotation about the axis; and (d) a feed screw shaft that is connected to the electric motor and passes vertically through the rotating jig while being screwed into a nut member fixed to the main body; and (e) the pin is moved axially together with the tip end of the feed screw shaft, thereby changing the amount of protrusion of the pin from the shoulder surface of the rotating jig.

According to the friction stir welding tool of the present invention, the amount of protrusion of the pin from the shoulder surface of the rotating jig is adjusted by the screw advancement of the feed screw shaft, which is rotated by an electric motor housed in the cylindrical main body. This makes the friction stir welding tool significantly smaller than when the amount of protrusion of the pin from the shoulder surface of the rotating jig is adjusted using a hydraulic cylinder, since it does not require a hydraulic cylinder, a hydraulic tank that returns hydraulic oil from the hydraulic cylinder, a hydraulic pump that supplies hydraulic oil in the hydraulic tank to the hydraulic cylinder, electromagnetic control valves that control the hydraulic oil from the hydraulic pump to the hydraulic cylinder, or a seal mechanism that supplies hydraulic pressure to the rotor.

Preferably, the opening at the tip of the cylindrical main body has a tapered inner circumferential surface that becomes larger toward the outside, and the base end of the rotating jig has a tapered outer circumferential surface that is in close contact with the tapered inner circumferential surface, and the base end of the rotating jig is fixed to the tip of the main body by an annular nut that is screwed onto a male thread formed on the outer circumferential surface of the tip of the cylindrical main body. This improves the centering accuracy between the main body and the rotating jig.

Preferably, a radial slit is formed in the base end of the rotating jig, opening on the end face of the base end of the rotating jig and penetrating from the inner peripheral surface to the outer peripheral surface of the base end of the rotating shaft, and the nut member is fitted to the inner peripheral surface of the base end of the rotating jig. This allows the nut member to be firmly fixed by the collet chuck structure tightened by the annular nut.

Preferably, the pin has a small diameter portion and a large diameter portion, and the rotating jig has a vertical hole that accommodates the feed screw shaft and into which the tip of the feed screw shaft is slidably fitted so as to be in contact with the large diameter portion of the pin, and a through hole that penetrates the bottom surface of the vertical hole so that the small diameter portion protrudes from the center of the shoulder surface. As a result, the load from the joined member applied to the pin is supported by the main body via the feed screw shaft, the annular nut to which the feed screw shaft is screwed, and the rotating jig to which the annular nut is fixed.

Preferably, a compression coil spring is inserted between the large diameter portion of the pin and the periphery of the through hole of the rotating jig. As a result, the pin is constantly biased toward the body by the compression coil spring, so that when the feed screw shaft is moved toward the body to reduce the amount of protrusion of the pin, the position of the pin is also moved by the amount of movement of the feed screw shaft.

Preferably, a bearing metal is fitted into the vertical hole of the rotating jig so that the tip of the feed screw shaft can slide therein. This allows the tip of the feed screw shaft to abut against the center of the end face of the large diameter part of the pin, so that buckling of the feed screw shaft is effectively suppressed when a load from the joined member is applied to the pin.

Preferably, the electric motor is fitted into the main body so that it cannot rotate around its axis but can move in the axial direction. As a result, the feed screw shaft is rotated and moved in the axial direction by the electric motor, and the amount of pin protrusion from the shoulder surface of the pin rotation jig is adjusted.

Preferably, the electric motor, the nut member, the feed screw shaft, and the pin are concentric with the main body and have a smaller diameter than the main body. This allows the friction stir welding tool to be configured in a single rod shape and to be compact.

1 is a diagram illustrating a friction stir welding apparatus including a friction stir welding tool according to an embodiment of the present invention. FIG. FIG. 2 is a front view partially including a longitudinal section showing the friction stir welding tool of FIG. 1 . 2 is an enlarged cross-sectional view showing a tip portion of the rotating jig of FIG. 1 . 4 is a cross-sectional view showing the tip portion of the rotating jig of FIG. 1, taken along line IV-IV of FIG. 3.

An embodiment of the present invention will be described below with reference to the drawings.

1 shows a friction stir welding apparatus 12 to which a friction stir welding tool 10 according to an embodiment of the present invention is applied. The friction stir welding apparatus 12 includes a fixed table 14 for fixing the workpieces W on a horizontal upper surface, a support 20 movably mounted on a base 16 in the X direction, which is a horizontal direction, and driven in the X direction by an X direction motor 18, a Y direction moving member 26 movably mounted on a Y direction guide member 22 fixed to the support 20 in the horizontal Y direction perpendicular to the X direction, and driven in the Y direction by a Y direction motor 24, a Z direction moving member 32 movably mounted on a Z direction guide member 28 fixed to the Y direction moving member 26 in the vertical direction, i.e., the Z direction, and driven in the Z direction by a Z direction motor 30, and a tool chuck 36 rotatably mounted on the Z direction moving member 32 around an axis in the Z direction, and driven to rotate around a vertical central axis by a tool drive motor 34 while holding the friction stir welding tool 10.

The friction stir welding tool 10 is equipped with a longitudinal rotating jig 40 having a shoulder surface 38 as its tip surface, which is rotated and lowered in the Z direction to come into surface contact with the workpieces W to generate frictional heat and soften the workpieces W, and a pin 42 which is moved in the X or Y direction while protruding from the center of the shoulder surface 38 toward the workpieces W to plastically deform and knead the joints of the workpieces W, thereby joining the atoms of the workpieces W together.

As shown in detail in FIG. 2, the friction stir welding tool 10 has a cylindrical body 44 whose base end (upper end in FIG. 2) is gripped by a tool chuck 36. A longitudinal rotating jig 40 that is concentric with the axis C1 of the body 44 is connected to the tip of the body 44. A longitudinal electric motor 46 is inserted into the body 44 so that it cannot rotate relatively around the axis C1 but can move in the axis C1 direction. For example, a plurality of longitudinal guide projections 48 in the axis C1 direction protruding from the outer peripheral surface of the electric motor 46 and a plurality of longitudinal guide projections 50 in the axis C1 direction protruding from the inner peripheral surface of the body 44 prevent the electric motor 46 from rotating relatively around the axis C1 while allowing movement in the axis C1 direction.

The opening at the tip end (lower end in FIG. 2) of the cylindrical main body 44 has a tapered inner peripheral surface 44a that becomes larger in diameter toward the outside, i.e., toward the bottom, of the main body 44. In addition, the base end (upper end in FIG. 2) 40a of the rotating jig 40 has a tapered outer peripheral surface 40b that is in close contact with the tapered inner peripheral surface 44a. A male thread 52 is formed on the outer peripheral surface of the tip end of the main body 44. The base end 40a of the rotating jig 40 has a larger diameter than the other parts. The annular nut 54 has a through hole 54a that is smaller in diameter than the base end 40a of the rotating jig 40. The annular nut 54 is screwed onto the male thread 52 with the rotating jig 40 inserted and the base end 40a of the rotating jig 40 engaged with the through hole 54a. As a result, the rotating jig 40 is fixed concentrically to the tip end of the main body 44.

The base end 40a of the rotating jig 40 has multiple radial slits 56 (for example, three slits) formed in the circumferential direction, which open on the upper end surface of the base end 40a of the rotating jig 40 and penetrate from the inner peripheral surface to the outer peripheral surface of the base end 40a of the rotating jig 40.

A nut member 60 is fitted into the opening of the base end 40a of the rotating jig 40, which is screwed into the base end 58a of the feed screw shaft 58, which has a male thread. The tapered inner circumferential surface 44a formed in the opening at the tip of the main body 44, the tapered outer circumferential surface 40b formed at the base end of the rotating jig 40 so as to be in close contact with the tapered inner circumferential surface 44a, the slit 56 formed in the base end 40a of the rotating jig 40, and the annular nut 54 that screws into the male thread 52 formed on the outer circumferential surface of the tip of the main body 44 to tighten the rotating jig 40 function as a collet chuck that removably fixes the nut member 60 to the main body 44.

The pin 42 has a small diameter portion 42a protruding from the shoulder surface 38 of the rotating jig 40 and a large diameter portion 42b located within the tip of the rotating jig 40. The rotating jig 40 has a vertical hole 62 that accommodates the feed screw shaft 58 and into which the tip of the feed screw shaft 58 fits so that the large diameter portion 42b of the pin 42 can slide and contact with the feed screw shaft 58, and a through hole 64 that penetrates the bottom surface of the vertical hole 62 so that the small diameter portion 42a protrudes from the center of the concave shoulder surface 38.

As shown in detail in FIG. 3, the vertical hole 62 has a larger diameter than the through hole 64, and a compression coil spring 66 is inserted between the large diameter portion 42b of the pin 42 and the bottom surface of the vertical hole 62 of the rotating jig 40, i.e., the periphery of the through hole 64, to constantly bias the pin 42 toward the large diameter portion 42b.

Cylindrical bearing metals 68 and 69 are fitted slidably into the tip and middle parts of the feed screw shaft 58 within the vertical hole 64 of the rotating jig 40. The bearing metal 68 centers and positions the tip part of the feed screw shaft 58 so that the tip part of the feed screw shaft 58 abuts against the center of the end face of the large diameter part 42b of the pin 42. The bearing metal 69 centers and positions the middle part of the feed screw shaft 58 so that the feed screw shaft 58 remains linear even when a large axial load is applied to the feed screw shaft 58.

The pin 42 is arranged to be non-rotatable relative to the rotating jig 40 but movable in the axial direction. For example, as shown in FIG. 4, which shows a cross section taken along line IV-IV in FIG. 3, a plurality of ridges 70 with triangular cross sections are formed in the direction of the axis C1 on the outer peripheral surface of the large diameter portion 42b of the pin 42, and a plurality of V-shaped grooves 72 that receive the ridges 70 are formed on the inner peripheral surface of at least the lower end of the vertical through hole 62 of the rotating jig 40.

The electric motor 46, nut member 60, feed screw shaft 58, and pin 42 have a smaller diameter than the main body 44 and are concentric with the main body 44. The electric motor 46 is, for example, a servo motor, and is provided with a motor drive circuit 74 and a motor control circuit 76. The motor control circuit 76 includes, for example, a receiving module that receives a command signal transmitted from a pin protrusion amount setting operation device (not shown) that is provided in a fixed position, and controls the amount of rotation of the electric motor 46 via the motor drive circuit 74 so that the pin protrusion amount P set by the pin protrusion amount setting operation device is obtained.

According to the friction stir welding tool 10 of this embodiment, the pin protrusion amount P of the pin 42 from the shoulder surface 38 of the rotating jig 40 is adjusted by the screw advancement of the feed screw shaft 58, which is rotated by the electric motor 46 housed in the cylindrical main body 44. As a result, compared to the case where the pin protrusion amount from the shoulder surface of the rotating jig is adjusted using a hydraulic cylinder, the hydraulic cylinder, the hydraulic tank that returns the hydraulic oil from the hydraulic cylinder, the hydraulic pump that supplies the hydraulic oil in the hydraulic tank to the hydraulic cylinder, the electromagnetic control valves that respectively control the hydraulic oil from the hydraulic pump to the hydraulic cylinder, and the seal mechanism that supplies hydraulic pressure to the rotor are not required, so the friction stir welding tool 10 can be significantly smaller.

In addition, according to the friction stir welding tool 10 of this embodiment, the opening at the tip of the cylindrical main body 44 is formed with a tapered inner peripheral surface 44a that becomes larger in diameter toward the outside, and the base end of the rotating jig 40 is formed with a tapered outer peripheral surface 40b that is in close contact with the tapered inner peripheral surface 44a, and the base end of the rotating jig 40 is fixed to the tip of the main body 44 by an annular nut 54 that is screwed onto a male thread 52 formed on the outer peripheral surface of the tip of the main body 44. This improves the centering accuracy between the main body 44 and the rotating jig 40.

In addition, according to the friction stir welding tool 10 of this embodiment, 56 radial slits are formed in the base end of the rotating jig 40, which open on the end face of the base end of the rotating jig 40 and penetrate from the inner peripheral surface to the outer peripheral surface of the base end of the rotating jig 40, and a nut member 60 is fitted to the inner peripheral surface of the base end of the rotating jig 40. As a result, the nut member 60 is firmly fixed by the collet chuck structure tightened by the annular nut 54.

In addition, according to the friction stir welding tool 10 of this embodiment, the pin 42 has a small diameter portion 42a and a large diameter portion 42b, and the rotating jig 40 has a vertical hole 62 that accommodates the feed screw shaft 58 and into which the tip of the feed screw shaft 58 is fitted so as to be able to contact and slide, and a through hole 64 that penetrates the bottom surface of the vertical hole 62 so that the small diameter portion 42a protrudes from the center of the shoulder surface 38. As a result, the load from the workpiece W applied to the pin 42 is supported by the main body 44 via the feed screw shaft 58, the annular nut 54 to which the feed screw shaft 58 is screwed, and the rotating jig 40 to which the annular nut 52 is fixed.

In addition, according to the friction stir welding tool 10 of this embodiment, a compression coil spring 66 is inserted between the large diameter portion 42b of the pin 42 and the periphery of the through hole 64 of the rotating jig 40. As a result, the pin 42 is constantly biased toward the main body 44 by the compression coil spring 66, so when the feed screw shaft 58 is moved toward the main body 44 to reduce the protrusion amount P of the pin 42, the position of the pin 42 is also moved by the amount of movement of the feed screw shaft 58.

In addition, according to the friction stir welding tool 10 of this embodiment, a bearing metal 68 into which the tip of the feed screw shaft 58 is slidably fitted is fitted into the vertical hole 62 of the rotating jig 40. This allows the tip of the feed screw shaft 58 to abut against the center of the end face of the large diameter portion 42b of the pin 42, so that buckling of the feed screw shaft 58 is suitably suppressed when a load from the workpiece W is applied to the pin 42.

In addition, according to the friction stir welding tool 10 of this embodiment, the electric motor 46 is fitted into the main body 44 so that it cannot rotate around its axis but can move in the axial direction. As a result, the feed screw shaft 58 is rotated and driven by the electric motor 46, and is moved in the axial direction, adjusting the amount of pin protrusion P of the pin 42 from the shoulder surface 38 of the rotating jig 40.

In addition, according to the friction stir welding tool 10 of this embodiment, the electric motor 46, the nut member 60, the feed screw shaft 58, and the pin 42 are concentric with the main body 44 and have a smaller diameter than the main body 44. As a result, the friction stir welding tool 10 is configured in a single rod shape and is compact.

The friction stir welding tool 10 has been described above with reference to the drawings, but this is merely one embodiment of the present invention, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

For example, in the above embodiment, the electric motor 46 is provided so as to be movable in the axial direction but not rotatable about the axis relative to the body 44. However, if a coupling is used between the output shaft of the electric motor 46 and the feed screw shaft 58, which connects the output shaft of the electric motor 46 so as to be non-rotatable in the axial direction but movable in the axial direction, the electric motor 46 may be fixed to the body 44.

In addition, in the above-described embodiment, the nut member 60 was fixed to the main body 44 via the rotating jig 40, but it may also be fixed directly to the main body 44.

In addition, in the above-mentioned embodiment, the bearing metal 68 and the bearing metal 69 are provided in the vertical hole 62 of the rotating jig 40, but in cases where the diameter of the feed screw shaft 58 is large and the bending strength is sufficiently high, one or both of the bearing metal 68 and the bearing metal 69 do not necessarily need to be provided.

In addition, in the above-mentioned embodiment, the small diameter portion 42a of the pin 42 and the rotating jig 40 are arranged so that they cannot rotate relative to each other around the axis but can move in the axial direction. However, the large diameter portion 42b of the pin 42 and the rotating jig 40 may be arranged so that they cannot rotate relative to each other around the axis but can move in the axial direction.

In addition, in the above-mentioned embodiment, a compression coil spring 66 is provided to bias the pin 42 toward the main body 44, but instead, the feed screw shaft 58 and the pin 42 may be connected in such a way that relative rotation is permitted but relative movement in the axial direction is not possible.

10: Friction stir welding tool 12: Friction stir welding device 38: Shoulder surface 40: Rotating jig 42: Pin 42a: Small diameter portion 42b: Large diameter portion 44: Main body 46: Electric motor 52: Male thread 54: Annular nut 54a: Through hole 56: Slit 58: Feed screw shaft 60: Nut member 62: Vertical through hole 64: Through hole 66: Compression coil spring 66: Compression coil spring 68: Bearing metal

Claims (7)

A friction stir welding tool comprising: a shaft-shaped rotating jig that can be moved toward and away from workpieces to be joined; and a pin that is provided on the rotating jig so as to be protruding from a shoulder surface formed at a tip of the rotating jig; and the tool is gripped by a tool chuck that is rotationally driven around the axis and moves in the axial direction,
a cylindrical body having a base end held by the tool chuck and a tip end to which the rotating jig is concentrically connected;
an electric motor inserted in the main body so as to be unable to rotate relatively around an axis;
a feed screw shaft connected to the electric motor and threadedly engaged with a nut member fixed to the main body, the feed screw shaft passing vertically through the rotating jig;
The friction stir welding tool, wherein the pin is moved axially together with the tip end of the feed screw shaft, so that the amount of protrusion of the pin from the shoulder surface of the rotating jig is changed. An opening at the tip of the cylindrical body is formed with a tapered inner circumferential surface that becomes larger in diameter toward the outside,
A tapered outer circumferential surface that is in close contact with the tapered inner circumferential surface is formed at a base end of the rotating jig,
The friction stir welding tool according to claim 1, characterized in that a base end of the rotating jig is fixed to the tip end of the cylindrical main body by an annular nut screwed onto a male thread formed on an outer peripheral surface of the tip end of the main body. A radial slit is formed in the base end of the rotating jig, the radial slit opening on the end face of the base end of the rotating jig and penetrating from the inner peripheral surface to the outer peripheral surface of the base end of the rotating shaft,
The friction stir welding tool according to claim 1 , wherein the nut member is fitted onto an inner peripheral surface of a base end portion of the rotating jig. The pin has a small diameter portion and a large diameter portion,
The rotating jig has a vertical through hole that accommodates the feed screw shaft and into which the large diameter portion of the pin is slidably fitted so that the tip of the feed screw shaft can come into contact with the large diameter portion of the pin.
The friction stir welding tool according to claim 1 , further comprising: a through hole penetrating a bottom surface of the vertical hole so that the small diameter portion protrudes from a center of the shoulder surface. 5. The friction stir welding tool according to claim 4, wherein a compression coil spring is interposed between the large diameter portion of the pin and a peripheral portion of the through hole of the rotating jig. 5. The friction stir welding tool according to claim 4, wherein a bearing metal is fitted into the vertical through hole of the rotating jig, into which the tip end of the feed screw shaft is slidably fitted. 2. The friction stir welding tool according to claim 1, wherein the electric motor, the nut member, the feed screw shaft and the pin are concentric with the main body and have a smaller diameter than the main body.

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