JP2012016763A - 2-axis drive unit and friction stir jointing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction stir jointing device in which a two-axis drive unit, having a compact configuration and capable of driving two axes for a long period of service life, is used in a drive system.SOLUTION: Ball-screw integrated linear guide units 10A, 10B are respectively configured as a mechanical part in which a ball screw 12 and a linear guide bearing 11 are integrated with each other by directly forming a ball-screw nut 17, being an element of the ball screw 12, on a slider 14 being an element of the linear guide bearing 11. A two-axis drive unit 5 has the following configuration. The two ball-screw integrated linear guide units 10A, 10B are combined with each other such that the sliders 14 of the respective units 10A, 10B are combined with each other by jointing mutual flanges 14a to each other so as to make the guide directions of the linear guide bearings 11 of the respective units 10A, 10B become two mutually intersecting axes.

Description

  The present invention uses a two-axis drive unit capable of linear guide driving in two crossing directions intersecting each other, and one axis of the two-axis drive unit is used as a pressure axis, and the other axis is used as an offset axis. The present invention relates to a friction stir welding apparatus.

Patent Document 1 describes a linear motion device in which a guide rail has a U-shaped cross section.
As shown in FIG. 10, the linear motion device includes a ball screw 213 having a screw shaft 211 and a nut 212, a linear motion guide bearing 216 having a guide rail 214 and a slider 215, and a nut 212 directly formed on the slider 215. It is integrated by doing. The guide rail 214 has a U-shaped cross section perpendicular to the longitudinal direction, and guides the slider 215 along the axial direction of the screw shaft 211 in a state where the slider 215 is accommodated in the concave portion of the U-shaped guide rail 214. . The guide rail 214 has a rolling surface 218 a that constitutes a rolling passage 218 of the rolling element 217 on the inner side surface of each sleeve portion 214 a disposed to face each side surface of the slider 215, and the slider 215 includes the guide rail 214. The rolling surface 218b is disposed opposite to the rolling surface 218a and constitutes the rolling passage 218.

Patent Document 2 describes an XY axis guide device for an XY drive unit.
As shown in FIG. 11, this XY-axis guide device is a combination of an X-axis linear guide device 231 and a Y-axis linear guide device 232 in a posture in which both axial directions are orthogonal to each other. The linear guide devices 231 and 232 include guide rails 233 and 236 and sliders 234 and 237, and are integrally assembled by coupling the sliders 234 and 237 to each other.

  Conventionally, as shown in FIG. 12, such an XY-axis guide device combines an X-axis slider center 231p and a Y-axis slider center 232p so as to coincide with each other. Here, the slider center is a point at the center in the longitudinal direction and at the center of the slider cross section when viewed from the upper surface of the slider. As shown in FIG. 12, this XY-axis guide device aligns the slider centers 231p and 232p with each other even when a vertical load is applied to the sliders 234 and 237 as indicated by the white arrows in the figure. To suppress the generation of moment.

  Further, in Patent Document 3, by rotating the welding tool while pressing it against the workpiece, frictional heat is generated at the contact point between the welding tool and the workpiece to soften and stir the material around the contact point. A friction stir welding method and apparatus are described in which a tool is immersed in a workpiece and the workpiece is linearly moved by moving the welding tool toward the surface of the workpiece after immersion.

  In this friction stir welding apparatus, as shown in FIG. 13, a pressure shaft 254 for moving the welding tool 251 in the axial direction is placed on the slider of the offset shaft 255 for horizontally moving the welding tool 251. A turning shaft 253 for rotating the welding tool 251 about its axis is mounted on the slider of the pressure shaft 254. In the pushing operation for immersing the welding tool 251 into the work 252, the welding tool 251 is pressed by the pressure shaft 254 against the work 252 while rotating the rotating tool 253, and the welding tool 251 is immersed in the work 252 to a predetermined depth. When the welding tool 251 is immersed in the workpiece 252, a pressure force is applied from the workpiece 252 along the central axis of the welding tool 251 to the tip of the welding tool 251 as a reaction force. Note that the offset shaft 255 is stopped in the pushing operation.

  After the welding tool 251 is immersed to a predetermined depth of the workpiece 252, the pressing shaft 254 is moved slightly by stopping or holding the pressure, and the offset shaft 255 is driven to move the welding tool 251 toward the surface of the workpiece 252. I do.

Japanese Utility Model Publication No. 2-12554 Japanese Unexamined Patent Publication No. Sho 62-28146 JP 2004-17128 A

  Incidentally, since the linear motion device described in Patent Document 1 is of a single-axis type, it has not been possible to perform two-axis driving. In addition, the XY guide device described in Patent Document 2 has a problem in that the equipment becomes large when including a drive system because a means for driving must be provided separately.

  Further, in the friction stir welding apparatus disclosed in Patent Document 3, the pressure shaft 254 for moving the welding tool 251 in the axial direction is placed on the slider of the offset shaft 255, so that it is necessary to increase the mounting area of the slider. There is a problem that the apparatus becomes large.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a biaxial drive unit and a friction stir welding apparatus that can perform biaxial drive with a long life with a compact configuration. is there.

In order to achieve the above-described object, a biaxial drive unit according to a first aspect of the present invention includes a guide rail having a substantially U-shaped cross section, and a slider disposed in a U-shaped recess of the guide rail. And a plurality of rolling elements arranged between the guide rail and the slider, and the guide rail has a rolling surface on the inner surface of each sleeve portion arranged to face the slider, The slider has a rolling surface disposed to face the rolling surface of the guide rail, and the rolling element is interposed between the rolling surface of the guide rail and the rolling surface of the slider, A linear motion guide bearing in which the slider and the guide rail are relatively movable,
A ball screw nut formed in parallel with the guide rail, a ball screw shaft penetrating the ball screw nut, and a plurality of screws disposed between the spiral groove of the ball screw nut and the spiral groove of the ball screw shaft. A ball screw comprising a ball,
Two ball screw integrated linear motion guide units each having the ball screw nut on the slider;
The two ball screw integrated linear motion guide units are combined with each other by combining the sliders of the units so that the guide directions of the linear motion guide bearings of each unit are two axes intersecting each other. Features.

The invention of claim 2 is the biaxial drive unit according to claim 1,
The sliders are combined so that the positions of the slider centers of one slider and the other slider are shifted along one of the two axes.

According to a third aspect of the present invention, there is provided a biaxial drive unit including a guide rail having a substantially U-shaped cross section, a slider disposed in a U-shaped recess of the guide rail, the guide rail, and the slider. A plurality of rolling elements disposed therebetween, wherein the guide rail has a rolling surface on an inner surface of each sleeve portion opposed to the slider, and the slider has the rolling surface of the guide rail. A rolling surface disposed opposite to the moving surface, and the rolling element is interposed between the rolling surface of the guide rail and the rolling surface of the slider, whereby the slider, the guide rail, A linear motion guide bearing that is relatively movable,
A ball screw nut formed in parallel with the guide rail, a ball screw shaft penetrating the ball screw nut, and a plurality of screws disposed between the spiral groove of the ball screw nut and the spiral groove of the ball screw shaft. A ball screw comprising a ball,
Two ball screw integrated linear motion guide units each having the ball screw nut on the slider;
The two ball screw integrated linear motion guide units are combined with each other by integrally forming the sliders of the units so that the guide directions of the linear motion guide bearings of each unit intersect with each other. It is characterized by.

The invention of claim 4 is the biaxial drive unit according to claim 3,
The sliders are integrated so that the positions of the centers of one slider and the other slider are shifted along one of the two axes.

The invention of claim 5 is the biaxial drive unit according to any one of claims 1 to 4,
At least one of the two ball screw integrated linear motion guide units constitutes a rolling path in which the rolling element moves between a rolling surface of the guide rail and a rolling surface of the slider, The slider is formed with a return passage of the rolling element, and a direction changing path that connects the return path and the rolling path, and the rolling element includes the rolling path, the direction changing path, and the return path. It circulates through an infinite circuit constituted by a passage.

The invention of claim 6 is the biaxial drive unit according to any one of claims 1 to 5,
In at least one of the two ball screw integrated linear motion guide units, the rolling element is a roller.

The invention of claim 7
By rotating the welding tool while pressing it against the workpiece, frictional heat is generated at the contact point between the welding tool and the workpiece to soften and agitate the material around the contact point, whereby the welding tool is applied to the workpiece. It is a friction stir welding apparatus that joins the workpieces linearly by moving the joining tool in the direction of the surface of the workpieces after immersion.
7. The biaxial drive according to claim 1, wherein the pressurizing shaft moves the joining tool in the axial direction thereof to approach / separate the workpiece and the offset shaft moves the joining tool in the surface direction of the workpiece. The biaxial drive unit described in any one of the items is used,
A guide rail of one of the linear motion guide bearings constituting the pressurizing shaft is fixed to a base, and a spindle on which the joining tool is mounted is fixed to the guide rail of the other linear motion guide bearing constituting the offset shaft. It is characterized by being.

The friction stir welding apparatus according to claim 8 is the friction stir welding apparatus according to claim 7,
At the start of an offset operation for moving the welding tool along the offset axis, the central axis of the welding tool constitutes the pressure axis when viewed from a direction perpendicular to the pressure axis and the offset axis. The linear motion guide bearing is disposed so as to pass through the center of the slider.

The invention of claim 9 is the friction stir welding apparatus according to claim 7 or 8,
The slider center of the slider of one of the linear motion guide bearings constituting the offset shaft is along the axis of the offset shaft with respect to the slider center of the slider of the other linear motion guide bearing constituting the pressure shaft. The slider center of one of the linear motion guide bearings constituting the offset shaft passes through a neutral position where the yawing moments acting on the offset shaft slider cancel each other. The distance between the slider centers or the distance between the welding tool and the slider center of one of the linear guide bearings constituting the offset shaft is set.

The invention of claim 10 is the friction stir welding apparatus according to claim 8 or 9,
The distance between the centers of the sliders is Ls, the inclination angle of the center axis of the welding tool with respect to the axis of the pressure axis is α, the applied pressure acting as a reaction force on the welding tool is F, and the welding tool from the slider center of the offset shaft When the distance to the tip of Dt is Dt, the offset load that is the resistance when moving the offset shaft is Fy, and the offset distance is Sy,
Ls≈Dt × Fy / (F × cos α) −Sy / 2
It is characterized by the relationship of

The invention of claim 11 is the friction stir welding apparatus according to any one of claims 8 to 10,
The center axis of the welding tool and the axis line of the turning axis motor for rotating the welding tool are shifted from each other.

The invention of claim 12 is the friction stir welding apparatus according to any one of claims 8 to 11,
By inserting an inclination imparting member between a spindle holding the joining tool and a turning axis bracket to which the turning axis motor is attached, and the two-axis drive unit, the center axis of the joining tool is set to the pressure axis. Inclined with respect to the axis.

  According to the present invention, since the sliders of the linear motion guide bearings of the two ball screw integrated linear motion guide units are coupled to each other or integrally molded, the object to be conveyed can be placed on the U-shaped guide rail. As compared with the case where the guide rail of the other linear motion guide bearing is placed on the slider of one linear motion guide bearing, the mounting area can be increased. Further, since the mounting area is not secured on the slider, it is not necessary to enlarge the slider, and the linear motion guide bearing can be downsized. In addition, each of the two axes has a ball screw as a driving means. Therefore, by fixing one guide rail to the base and fixing the object to be conveyed to the other guide rail, the two axes can be configured in a compact configuration. Drive can be performed.

It is a side view of the friction stir welding apparatus of one Embodiment of this invention. It is a top view of the biaxial drive unit integrated in the friction stir welding apparatus of FIG. It is a side view of the biaxial drive unit of FIG. FIG. 3 is a cross-sectional view of a ball screw integrated linear motion guide unit used in the biaxial drive unit of FIG. 2. It is a front view of a friction stir welding apparatus. It is a front view which shows the relationship of the force at the time of pushing-in operation | movement in a friction stir welding apparatus. In a friction stir welding apparatus, it is a front view which shows the relationship of the force at the time of offset. In a friction stir welding apparatus, it is a characteristic view which shows the relationship between the center-to-center distance of two sliders at the time of pushing operation and offset operation, and the surface pressure of a rolling element. It is a front view of the friction stir welding apparatus which concerns on a modification. It is a block diagram of the linear motion apparatus of patent document 1, (a) is a perspective view, (b) is BB arrow sectional drawing of (a). It is a perspective view which shows the structure of the XY-axis guide apparatus of patent document 2. FIG. It is a schematic diagram explaining the center position of two sliders of the XY-axis guide apparatus of FIG. It is a perspective view which shows an example of the friction stir welding apparatus of patent document 3. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 is a side view of a friction stir welding apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of a biaxial drive unit incorporated in the friction stir welding apparatus of FIG. 1, and FIG. 3 is a biaxial drive of FIG. 4 is a side view of the unit, FIG. 4 is a sectional view of a ball screw integrated linear motion guide unit used in the biaxial drive unit of FIG. 2, and FIG. 5 is a front view of the friction stir welding apparatus.

  As shown in FIG. 1, the friction stir welding apparatus M includes a pressurizing shaft 2 that brings a welding tool 1 for friction stir welding to approach / separate a workpiece, and the welding tool 1 is substantially orthogonal to the pressurizing shaft 2. An offset shaft 3 that moves in the direction and a pivot shaft 4 that rotates the welding tool 1 around its central axis Q (see FIG. 5) are provided. Here, the pressurizing shaft 2 is set as the X axis of the X axis and the Y axis orthogonal to each other, and the offset shaft 3 is set as the Y axis. The pressurizing shaft 2 and the offset shaft 3 form two axes perpendicular to each other of the biaxial drive unit 5.

  As shown in FIGS. 2 and 3, the biaxial drive unit 5 includes a first ball screw integrated linear motion guide unit 10 </ b> A and a second ball screw integrated linear motion guide unit 10 </ b> B in the axial direction of both. It is configured by setting and combining them in a relationship orthogonal to each other.

  The first ball screw-integrated linear motion guide unit 10A that constitutes the pressure shaft 2 (X-axis) and the second ball screw-integrated linear motion guide unit 10B that constitutes the offset shaft 3 (Y-axis), respectively, For example, as shown in FIG. 4, the linear motion guide bearing 11 and the ball screw 12 are combined.

  The linear motion guide bearing 11 is disposed between a guide rail 13 having a substantially U-shaped cross section, a slider 14 disposed in a U-shaped recess of the guide rail 13, and between the guide rail 13 and the slider 14. A plurality of rolling elements 15. The guide rail 13 has a rolling surface 16A on the inner side surface of each sleeve portion 13A arranged to face the slider 14, and the slider 14 has a rolling surface 16B arranged to face the rolling surface 16A of the guide rail 13. And a rolling element (roller in the figure) 15 is interposed between the rolling surface 16A of the guide rail 13 and the rolling surface 16B of the slider 14, so that the slider 14 and the guide rail 13 are relative to each other. It is possible to move straight.

  In this case, between the rolling surface 16 </ b> A of the guide rail 13 and the rolling surface 16 </ b> B of the slider 14, the rolling passages 16 in which the rolling elements 15 move are vertically arranged in two rows vertically, i.e., two-to-four rows as a whole. It is formed. The slider 14 is formed with a return path 16D of the rolling element 15 and a direction changing path (not shown) that connects the return path 16D and the rolling path 16 so that the rolling element 15 changes direction with the rolling path 16. It circulates through an infinite circulation path composed of a path and a return path 16D.

  The ball screw 12 includes a ball screw nut 17 formed in parallel with the guide rail 13, a ball screw shaft 18 passing through the ball screw nut 17, a spiral groove of the ball screw nut 17, and a spiral groove of the ball screw shaft 18. And a plurality of balls 19 disposed between the two. The ball screw-integrated linear motion guide units 10A and 10B directly form the ball screw nut 17 that is an element of the ball screw 12 on the slider 14 that is an element of the linear motion guide bearing 11, thereby It is comprised as a mechanism component provided integrally with the dynamic guide bearing 11.

  Further, as shown in FIG. 3, the biaxial drive unit 5 is configured to guide the first and second ball screw integrated linear motion guide units 10A and 10B to the linear motion guide bearing 11 of each unit 10A and 10B. The sliders 14 of the units 10A and 10B are coupled to each other by a coupling means such as a bolt so that the directions (axis directions) intersect with each other (substantially orthogonal in the present embodiment). It is configured by combining with each other. The two sliders 14 may be integrally formed from the beginning.

  As shown in FIG. 2, the first and second two ball screw integrated linear motion guide units 10A and 10B are, as shown in FIG. 2, the first ball screw integrated linear motion guide unit 10A on the X axis (pressure shaft 2) side. Slider center PA (hereinafter also referred to as “pressure axis slider center” or “X axis slider center”) and Y axis (hereinafter also referred to as “pressure axis slider center” or “X axis slider center”). The slider center PB (hereinafter, “offset axis slider center”) of the slider 14 (hereinafter also referred to as “offset axis slider” or “Y axis slider”) of the second ball screw integrated linear motion guide unit 10B on the offset axis 3) side. ”Or“ Y-axis slider center ”), and the sliders 14 are coupled to each other, and the two sliders 14 are combined. Central PA, the distance between the PB (shift amount Ls) is arbitrarily set. Here, the slider center is a point at the center of the effective length along the longitudinal axis direction and at the center of the slider cross section when viewed from the slider upper surface.

  In this case, the offset axis slider center PB is displaced along the axis of the offset axis 3 with respect to the pressure axis slider center PA. That is, the axis of the offset shaft 3 passes over the pressure shaft slider center PA, and the offset shaft slider center PB is located on the axis of the offset shaft 3. Moreover, the offset axis slider center PB is displaced in the direction opposite to the advancing direction YA during the offset operation of the welding tool 1 (rightward direction in FIGS. 2 and 5) with respect to the pressure axis slider center PA. Yes.

  As shown in FIG. 1, the friction stir welding apparatus M configured with the pressure shaft (X axis) 2 and the offset shaft (Y axis) 3 by using the biaxial drive unit 5 in this way is configured to connect the welding tool 1 to a workpiece ( By rotating while pressing against the workpiece (not shown), frictional heat is generated at the contact point between the welding tool 1 and the workpiece to soften and stir the material around the contact point, thereby causing the welding tool 1 to be immersed in the workpiece. After the immersion, the work is joined in a line by moving the joining tool 1 in the surface direction of the work.

  The pressing shaft 2 moves the joining tool 1 in the axial direction of the pressing shaft 2 to approach / separate the workpiece. The offset shaft 3 moves the joining tool 1 in the workpiece surface direction (Y-axis), which is a direction orthogonal to the pressing shaft 2. The guide rail 13 of the first ball screw-integrated linear motion guide unit 10A constituting the pressing shaft 2 is fixed to the base end of a C-shaped arm 50 as a base via a plate 58, thereby constituting the offset shaft 3. A spindle 30 on which the joining tool 1 is rotatably mounted is fixed to the guide rail 13 of the second ball screw integrated linear motion guide unit 10B. Accordingly, the slider 14 of the pressure shaft 2 and the guide rail 13 of the offset shaft 3 are driven by the ball screw 12 of the pressure shaft 2 and the ball screw 12 of the offset shaft 3, respectively. The ball screw 12 of the pressure shaft 2 and the ball screw 12 of the offset shaft 3 are driven by a pressure shaft motor 42 and an offset shaft motor 43 through belts 41A and 41B, respectively.

  The welding tool 1 is rotatably held via a tool holder 35 by a spindle 30 that constitutes a turning shaft 4, and a tool base 1a that protrudes downward from a columnar tool base 1a and a shoulder 1b on the lower end surface of the tool base. A tool pin 1c having a smaller outer diameter. The spindle 30 includes a spindle housing 32 that houses a plurality of bearings 31, a bearing 31, and a spindle shaft 33 that is rotatably held by the bearing 31. A tool holder 35 for holding 1 in a detachable manner is provided. The spindle shaft 33 is driven by a turning shaft motor 44 via a pulley 46 and a belt 47. The spindle 30 and the turning shaft motor 44 are fixed to the mounting surface 13 a of the guide rail 13 of the offset shaft 3 via the turning shaft bracket 48.

  Since the spindle shaft 33 is driven via the belt 47 as described above, the joining tool 1 and the turning shaft motor 44 are misaligned. In other words, the point of action of external load for the biaxial drive unit 5 is defined as the normal direction of the mounting surface 13a (the surface on which the pivot shaft bracket 48 is fixed to the guide rail 13 of the offset shaft 3) (arrow Z direction, Hereinafter, it can also be kept low.

  As a result, the pitching moment acting on the slider 14 of the pressure shaft 2 and the rolling moment acting on the slider 14 of the offset shaft 3 can be kept small, and as a result, the surface pressure acting on the rolling element 15 can be reduced. Become.

  In addition, since the slider 14 of the offset shaft 3 and the slider 14 of the pressure shaft 2 are coupled, the guide rail 13 of the offset shaft 3 becomes a member that supports the spindle 30, so that the mounting area of the spindle 30 can be increased, The applied pressure from the welding tool 1 can be received by the large area of the side surface 13b of the guide rail 13 with the offset 3.

  As shown in FIG. 7, a taper give 49 (inclination imparting member) is provided between the pivot shaft bracket 48 and the side surface 13 b of the guide rail 13 of the offset shaft 3, and the center axis Q of the welding tool 1 is pressurized. Inclined with respect to the axis of the shaft 2. The direction of inclination is a direction in which the welding tool 1 is offset (advanced) in the offset operation. By inclining the joining tool 1 in this manner, the shoulder portion 1b of the joining tool 1 can be brought into contact with the workpiece at an angle with respect to the traveling direction of the joining tool 1 during the offset operation. As a result, the fluidized workpiece material flows into the wedge portion 1b of the welding tool 1 in a wedge shape, so that the pressing force can be maintained without moving the pressing shaft 2 greatly. become.

  Returning to FIG. 1, a pressure detection means 51 and a backing member 52 are provided at the tip of a C-shaped arm (base) 50 to which the guide rail 13 of the pressure shaft 2 is fixed. Then, by sandwiching the work between the joining tool 1 and the backing member 52, the joining tool 1 can apply pressure to the work.

Next, the relationship between the operation at the time of joining and the force acting during the operation will be described.
The welding tool 1 rotates at a high speed by driving the turning shaft motor 44. In the push-in operation for immersing the welding tool 1 into the workpiece, the pressure shaft motor 42 is driven and the ball screw shaft 18 of the pressure shaft 2 is rotated via the belt 41A, whereby the slider 14 of the pressure shaft 2 is moved. Move down. When the slider 14 of the pressure shaft 2 is moved downward, the welding tool 1 is moved downward in the X-axis direction via the offset shaft 3 and the spindle 30, and the welding tool 1 is pressed against the workpiece while rotating at high speed, The workpiece material is softened and agitated at and around the contact point. And the joining tool 1 is immersed in a workpiece | work to predetermined depth, stirring. Next, after immersing the welding tool 1 to a predetermined depth of the workpiece, an offset operation is performed while the pressure shaft 2 is finely moved along with stopping or holding the pressure.

  In the offset operation, the guide rail 13 of the offset shaft 3 is moved by driving the offset shaft motor 43 and rotating the ball screw shaft 18 of the offset shaft 3 via the belt 41B. When the guide rail 13 of the offset shaft 3 is moved, the joining tool 1 is moved in the Y axis direction (YA direction) together with the spindle 30. By this movement, the contact point and the stirring region of the joining tool 1 with respect to the workpiece move, and the workpiece is joined linearly. After moving the predetermined offset distance, the ball screw shaft 18 of the pressure shaft 2 is rotated in the opposite direction to the previous direction, so that the joining tool 1 is moved upward in the X-axis direction and detached from the workpiece. Thus, the friction stir welding is performed by the pushing operation and the offset operation.

6 and 7 are front views showing the relationship between the force during the pushing operation and the offset operation of the friction stir welding apparatus M. FIG.
First, the pushing operation will be described with reference to FIG. At the time of the pushing operation, the pressurizing force F acts as a reaction force on the slider 14 of the pressing shaft 2 along with the operation of immersing the welding tool 1 into the workpiece. The point of action of the pressing force F (the central axis position of the welding tool 1) is away from the slider 14 of the pressing shaft 2 in the normal direction Z of the mounting surface, so that the pitching moment due to the pressing force is increased by the pressing shaft. 2 acts on the second slider 14.

  During the pushing operation (at the start of the offset operation), it is desirable that the yawing moment Mx1 (not shown) does not act on the slider 14 of the pressure shaft 2. Specifically, the center axis Q of the welding tool 1 is disposed so as to pass over the slider center PA of the pressing shaft 2, that is, a direction perpendicular to the pressing shaft 2 and the offset shaft 3 (Z It is desirable that it is disposed so as to pass through the pressure axis slider center PA as viewed from the direction).

  For example, as shown in FIG. 6, when the distance between the slider center PA of the pressing shaft 2 and the center axis Q of the welding tool 1 at the operation start position of the offset shaft 3 is Dk, the setting is made so that Dk = 0. It is desirable to keep it. In such a case, since the yawing moment Mx1 due to the applied pressure F does not act on the slider 14 of the pressure shaft 2 at the start of the offset operation, the surface pressure of the rolling element 15 is reduced at both ends of the slider, and the slider 14 of the pressure shaft 2 The lifespan of is extended.

  Since the offset axis slider center PB is deviated from the pressure axis slider center PA, the applied force F acts as a lateral load at a position displaced from the offset axis slider center PB. My1 acts on the slider 14 of the offset shaft 3. Due to the action of the yawing moment My1, the surface pressure of the rolling element 15 rises at both ends of the slider of the offset shaft 3 as compared with the case where the center axis Q of the welding tool 1 is disposed above the offset shaft slider center PB. To do. However, since the offset shaft 3 is stopped in the pushing operation, the rolling element 15 does not roll on the rolling surface, and the life reduction due to the increase in the surface pressure does not occur from the viewpoint of the rolling life.

  Further, the point of application of the applied pressure F (the central axis position of the welding tool 1) is away from the offset axis slider center PB in the mounting surface normal direction Z, so that the applied pressure F is applied to the slider 14 of the offset axis 3. Acts as a rolling moment.

Next, the offset operation will be described with reference to FIG.
During the offset operation, the slider 14 of the pressurizing shaft 2 has a pitching moment due to the applied force F, a yawing moment Mx2 caused by the applied force F generated by the movement of the offset shaft 3, and a yawing moment Mx3 caused by the offset load Fy. And act. The yawing moment Mx2 is caused by an increase in the distance between the center axis Q of the welding tool 1 and the pressure axis slider center PA, which is caused by the movement of the offset shaft 3.

  During the offset operation, the surface pressure of the rolling elements 15 at both ends of the slider of the pressurizing shaft 2 increases due to the action of the yawing moment Mx3 due to the offset load Fy as compared with the pushing operation. However, since the slider 14 of the pressurizing shaft 2 is stopped or slightly moved in the offset operation, the rolling element 15 hardly rolls on the rolling surface, and this is caused by the increase in the surface pressure from the viewpoint of the rolling life. There is no reduction in service life.

  The lateral load and the rolling moment described above act on the slider 14 of the offset shaft 3. Further, as the guide rail 13 of the offset shaft 3 moves and the welding tool 1 moves in the Y-axis direction by the offset operation, the applied force F acts on a position shifted from the slider center PB of the offset shaft 3. Therefore, the yawing moment My2 (counterclockwise on the paper surface) due to the applied pressure F acts. Further, a yawing moment My3 (clockwise on the paper surface) due to the offset load Fy also acts.

Here, the distance between the slider centers PA and PB is Ls, the offset movement amount (displacement amount from the initial position) of the offset shaft 3 is Yf, and the pressure axis slider at the operation start position (Yf = 0) of the offset shaft 3 When the distance between the center PA and the center axis Q of the welding tool 1 is Dk, and the inclination angle of the center axis Q of the welding tool 1 with respect to the axis of the pressure shaft 2 is α, the offset axis slider center PB and the center axis of the welding tool 1 The distance Df from Q is
Df = (Ls + Yf) cos α + Dk
It becomes.

When the applied pressure is F, the distance from the offset axis slider center PB to the tip of the welding tool 1 is Dt, and the offset load is Fy, the yawing moment My2 due to the applied force F and the yawing moment My3 due to the offset load are clockwise in FIG. Is positive,
My2 = −F × Df = −F × (Ls + Yf) cos α−F × Dk
My3 = Fy × Dt
It becomes.

Therefore, the sum My of the yawing moment acting on the slider 14 of the offset shaft 3 is
My = My2 + My3 = Fy × Dt−F × (Ls + Yf) cos α−F × Dk (1)
It becomes.

  From the above formula, compared to the case where the distance between the slider centers PA and PB is not shifted (when Ls = 0), the offset axis slider center PB is more reverse to the traveling direction YA of the welding tool 1 than the pressure axis slider center PA. It can be seen that when the direction is shifted (Ls> 0), the total of the yawing moments My = My2 + My3 acting on the slider 14 of the offset shaft 3 can be reduced.

  Here, the distance Ls between the slider centers PA and PB so that the offset axis slider center PB passes through the yawing moment neutral position where the total yawing moment acting on the slider 14 of the offset axis 3 becomes zero, or By setting the distance Dt between the tip of the welding tool 1 and the offset axis slider center PB, the life of the slider 14 of the offset axis 3 can be further extended.

In order to allow the offset axis slider center PB to pass the yawing moment neutral position (My = 0), as obtained from the modification of the above equation (1),
Yf + Ls = Dt × Fy / (F × cos α) −Dk / cos α
Should be set to be.

If the offset distance is Sy,
0 ≦ Yf ≦ Sy
So,
0 ≦ Dt × Fy / (F × cosa) −Dk / cos α−Ls ≦ Sy
That is, Dt × Fy / (F × cos α) −Dk / cos α-Sy
≦ Ls ≦ DtxFy / (F × cos α) −Dk / cos α
The distance Ls between the slider centers may be set within the range of

further,
Ls = Dt × Fy / (F × cos α) −Sy / 2
If Dk = 0,
My = F × (Yf−Sy / 2) cos α, (0 ≦ Yf ≦ Sy)
Thus, since the magnitude of the yawing moment acting on the slider 14 of the offset shaft 3 when Yf changes from 0 to Sy during the offset operation can be minimized, the life can be extended most.

  As described above, by shifting the slider centers PA and PB, in the operation in which the slider 14 of each of the pressure shaft 2 and the offset shaft 3 is driven, an excessive yawing moment is not generated, and the surface pressure of the rolling element is reduced. Both ends can be reduced, and the lifetimes of both the slider 14 of the pressure shaft 2 and the slider 14 of the offset shaft 3 can be extended. Therefore, the joining head (the friction stir welding apparatus M of the present embodiment including the arm 50) can be made compact and light, and the size of the robot arm that drives the joining head can be reduced.

Examples of the friction stir welding apparatus according to the present invention will be described below.
The offset load is determined by the joining conditions. For example, an aluminum plate (workpiece) having a thickness of 2 mm is friction stir welded using a cylindrical joining tool 1 having a shoulder diameter of Φ10 mm, a tool pin height of 3 mm, and a tool pin diameter of Φ4. In this case, the offset load was Fy = 500 N when the applied pressure F = 5000 N, the welding tool troublesome angle α = 3 °, and the moving speed of the offset shaft was 20 mm / s.

Offset distance Sy = 5 mm, distance Dt = 40 mm from offset axis slider center PB to tool tip, and distance between pressure axis slider center PA and center axis Q of welding tool 1 at the offset axis operation start position as Dk = 0 mm If the distance Ls between the slider centers PA and PB is
35mm ≦ Ls ≦ 40mm
By doing so, the offset axis slider center PB can pass through the neutral position of the yawing moment, and the life of the offset axis slider can be further extended. In particular, the life can be extended most by setting Ls = 37.5 mm.

  In FIG. 8, the horizontal axis shows the distance Ls between the slider centers, and the vertical axis shows the surface pressure at both ends of the offset shaft slider at the offset shaft operation start position in each of the indenting operation and the offset operation.

  When the slider center distance Ls = 0, the surface pressure in the pushing operation is suppressed, but the surface pressure in the offset operation is high. In this case, since the offset shaft is driven in the offset operation (the rolling element rolls), the life of the offset shaft slider is expected to be shortened.

  As the slider center distance Ls increases, the surface pressure in the pushing operation increases, and the surface pressure in the offset operation is suppressed. Even if the surface pressure is increased by the pushing operation, the offset shaft 3 is stopped during the pushing operation, so that the life of the offset shaft slider is not affected. By suppressing the surface pressure in the offset operation, the life of the offset shaft slider is expected to be extended.

  When the slider center distance Ls = 37.5 mm, the surface pressure at the offset axis operation start position is not minimal, but the offset axis position (movement amount Yf) changes from 0 to 5 mm due to the offset operation (calculation). The surface pressure is equivalent to the case where the distance Ls between the slider centers changes from 37.5 mm to 42.5 mm), and it can be seen that the surface stress in the offset operation is minimized.

  In the above description, the slider center distance Ls is obtained from the joining conditions and the distance Dt between the offset axis slider center PB and the tip of the joining tool 1, but the slider center distance Ls is determined from the predetermined slider center distance Ls. A distance Dt between the slider center PB and the tip of the welding tool 1 may be derived.

  As described above, according to the friction stir welding apparatus M of the present embodiment, the sliders 14 of the linear motion guide bearings 11 of the two ball screw integrated linear motion guide units 10A and 10B are combined or integrally formed. As a result, the object to be conveyed can be placed on the U-shaped guide rail 13, so that the mounting area is increased compared to the case where the guide rail of the other linear motion guide bearing is placed on the slider of the first linear motion guide bearing. be able to. In addition, since the mounting area is not secured in the slider 14, it is not necessary to enlarge the slider 14, and the linear guide bearing 11 can be downsized. In addition, each of the two axes includes a ball screw 12 as a driving means. Therefore, by fixing one guide rail 13 to the arm 50 and fixing the object to be conveyed to the other guide rail 13, a compact structure can be obtained. Two-axis drive can be performed with the configuration.

  Further, since the two sliders 14 are coupled, the positional deviation amount at the center of the slider can be arbitrarily adjusted by coupling the sliders 14 after adjusting the positions of the sliders 14. Note that the two sliders 14 may be integrally formed instead of joining the two sliders 14 together. In this case, by integrally molding the two sliders 14, it is not necessary to adjust the two axes at the time of assembly, and the assemblability is improved.

  Further, since the sliders 14 are coupled so that the positions of the center of both sliders of the one slider 14 and the other slider 14 are shifted along one of the two axes, it contributes to the reduction of the yawing moment. be able to.

  In addition, by using a roller as the rolling element, it is possible to provide a high load bearing strength, and it is possible to reduce the size and to reduce the size of the apparatus.

  Further, the biaxial drive unit 5 is used for driving the pressure shaft 2 and the offset shaft 3 of the friction stir welding apparatus M, and the guide rail 13 of one linear guide bearing 11 constituting the pressure shaft 2 is armed. Since the spindle 30 with the welding tool 1 attached thereto is fixed to the guide rail 13 of the other linear guide bearing 11 constituting the offset shaft 3, the friction stir welding apparatus M is made compact and the configuration is simplified. Can be realized.

  Further, since the center axis Q of the welding tool 1 passes through the slider center PA of the pressurizing shaft 2 at the start of the offset operation, no yawing moment is generated on the pressurizing shaft 2 at the start of the offset operation. Can do.

  Further, the slider center PA of the pressure shaft 2 and the slider center PB of the offset shaft 3 are shifted from each other, and the yawing moment due to the applied pressure and the yawing moment due to the offset load cancel each other in the offset operation of the slider center PB of the offset shaft 3. Since it is arranged so as to pass through the position, it is possible to avoid an excessive yawing moment during the offset operation, and it is possible to extend the life of the apparatus by reducing the surface pressure at both ends of the slider. Further, since the joining head portion from the joining tool 1 to the pressure shaft 2 can be made compact and light, the size of the robot arm that drives the joining head can be reduced.

  Further, by setting the distance Ls between the slider centers so as to satisfy Ls≈Dt × Fy / (F × cos α) −Sy / 2, it is possible to move the welding tool 1 and the guide rail 13 of the offset shaft 3 in the offset operation. Accordingly, the central axis Q of the welding tool 1 moves relative to the centers of both sliders, but the yawing moment at that time can be minimized, so that the life of the apparatus can be further extended.

  Further, since the welding tool 1 and the turning shaft motor 44 are arranged in the wrong center, the height of the welding tool 1, that is, the point of application of external load for the two-axis drive unit, regardless of the position of the axis of the turning shaft motor 44. , It can be kept low in the normal direction of the mounting surface 13a. As a result, the pitching moment acting on the slider 14 of the pressure shaft 2 and the rolling moment acting on the slider 14 of the offset shaft 3 can be kept small.

  Further, since the center axis Q of the welding tool 1 is inclined with respect to the axis of the pressing shaft 2, the work material fluidized in the offset operation flows into the shoulder portion 1b of the welding tool 1 in a wedge shape. Is generated, and the applied pressure can be maintained without largely moving the pressurizing shaft 2.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the material, shape, dimensions, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

  For example, in the above-described embodiment, the case where a roller is used as each rolling element has been described. However, a ball may be used, or the rolling element of a certain linear motion guide bearing may be a roller and the rolling motion of another linear motion guide bearing may be used. The moving body may be a combination such as a ball.

  In the above-described embodiment, the linear motion guide bearing 11 is a linear motion guide bearing having a direction changing path and a return path 16D and circulating the rolling elements 15 in the rolling path 16, but is not limited thereto. Alternatively, a non-circulation type linear motion guide bearing that does not include a mechanism for circulating the rolling elements 15 may be used.

  Moreover, in the said embodiment, although the center axis Q of the joining tool 1 was inclined with respect to the axis line of the pressurization axis | shaft 2, it is not limited to this, As shown in FIG. The pressure axis 2 may be set parallel to the axis.

  In the above-described embodiment, the belt method is adopted as a method for transmitting the power of the pressure shaft motor 42 and the offset shaft motor 43 to the ball screw shaft 18 of the pressure shaft 2 or the offset shaft 3. The ball screw shaft 18 may be driven directly by the motors 42 and 43 via gears. Higher responsive control is possible by driving directly through the coupling.

M Friction stir welding equipment PA Pressurization shaft slider center (slider center of linear motion guide bearing slider)
PB Offset shaft slider center (slider center of linear motion guide bearing slider)
DESCRIPTION OF SYMBOLS 1 Joining tool 2 Pressure axis | shaft 3 Offset axis | shaft 5 Turning axis | shaft 5 2 axis | shaft drive unit 10A 1st ball screw integrated linear motion guide unit (pressure axis | shaft, X axis)
10B Second ball screw integrated linear motion guide unit (offset axis, Y axis)
DESCRIPTION OF SYMBOLS 11 Linear motion guide bearing 12 Ball screw 13 Guide rail 13A Sleeve part 14 Slider 15 Rolling element (roller or ball)
16 Rolling path 16A Rolling surface on the guide rail side 16B Rolling surface on the slider side 17 Ball screw nut 18 Ball screw shaft 19 Ball 30 Spindle 42 Pressure shaft motor 43 Offset shaft motor 44 Swing shaft motor 48 Swing shaft bracket 49 Tapered give (Inclination imparting member)

Claims (12)

A guide rail having a substantially U-shaped cross section; a slider disposed in a U-shaped recess of the guide rail; and a plurality of rolling elements disposed between the guide rail and the slider. The guide rail has a rolling surface on an inner surface of each sleeve portion arranged to face the slider, and the slider has a rolling surface arranged to face the rolling surface of the guide rail. The rolling guide is interposed between the rolling surface of the guide rail and the rolling surface of the slider so that the slider and the guide rail are relatively movable. A bearing,
A ball screw nut formed in parallel with the guide rail, a ball screw shaft penetrating the ball screw nut, and a plurality of screws disposed between the spiral groove of the ball screw nut and the spiral groove of the ball screw shaft. A ball screw comprising a ball,
Two ball screw integrated linear motion guide units each having the ball screw nut on the slider;
The two ball screw integrated linear motion guide units are combined with each other by combining the sliders of the units so that the guide directions of the linear motion guide bearings of each unit are two axes intersecting each other. A featured two-axis drive unit.   2. The sliders are coupled to each other so that the positions of the slider centers of one slider and the other slider are shifted along one of the two axes. 2-axis drive unit. A guide rail having a substantially U-shaped cross section; a slider disposed in a U-shaped recess of the guide rail; and a plurality of rolling elements disposed between the guide rail and the slider. The guide rail has a rolling surface on an inner surface of each sleeve portion arranged to face the slider, and the slider has a rolling surface arranged to face the rolling surface of the guide rail. The rolling guide is interposed between the rolling surface of the guide rail and the rolling surface of the slider so that the slider and the guide rail are relatively movable. A bearing,
A ball screw nut formed in parallel with the guide rail, a ball screw shaft penetrating the ball screw nut, and a plurality of screws disposed between the spiral groove of the ball screw nut and the spiral groove of the ball screw shaft. A ball screw comprising a ball,
Two integrated ball screw integrated linear motion guide units having the ball screw nut provided in the slider;
The two ball screw integrated linear motion guide units are combined with each other by integrally forming the sliders of the units so that the guide directions of the linear motion guide bearings of each unit intersect with each other. 2-axis drive unit characterized by this.   The sliders are integrally molded so that the positions of the slider centers of the one slider and the other slider are shifted along one of the two axes. The two-axis drive unit described.   At least one of the two ball screw integrated linear motion guide units constitutes a rolling path in which the rolling element moves between a rolling surface of the guide rail and a rolling surface of the slider, The slider is formed with a return passage of the rolling element, and a direction changing path that connects the return path and the rolling path, and the rolling element includes the rolling path, the direction changing path, and the return path. The two-axis drive unit according to any one of claims 1 to 4, wherein the two-axis drive unit circulates through an infinite circuit constituted by a passage.   The biaxial drive unit according to any one of claims 1 to 5, wherein at least one of the two ball screw integrated linear motion guide units, the rolling element is a roller. By rotating the welding tool while pressing it against the workpiece, frictional heat is generated at the contact point between the welding tool and the workpiece to soften and agitate the material around the contact point, whereby the welding tool is applied to the workpiece. It is a friction stir welding apparatus that joins the workpieces linearly by moving the joining tool in the direction of the surface of the workpieces after immersion.
7. The biaxial drive according to claim 1, wherein the pressurizing shaft moves the joining tool in the axial direction thereof to approach / separate the workpiece and the offset shaft moves the joining tool in the surface direction of the workpiece. The biaxial drive unit described in any one of the items is used,
A guide rail of one of the linear motion guide bearings constituting the pressurizing shaft is fixed to a base, and a spindle on which the joining tool is mounted is fixed to the guide rail of the other linear motion guide bearing constituting the offset shaft. A friction stir welding apparatus characterized by being made.   At the start of an offset operation for moving the welding tool along the offset axis, the central axis of the welding tool constitutes the pressure axis when viewed from a direction perpendicular to the pressure axis and the offset axis. 8. The friction stir welding apparatus according to claim 7, wherein the friction stir welding apparatus is disposed so as to pass through a slider center of one of the linear motion guide bearings.   The slider center of the slider of one of the linear motion guide bearings constituting the offset shaft is along the axis of the offset shaft with respect to the slider center of the slider of the other linear motion guide bearing constituting the pressure shaft. The slider center of one of the linear motion guide bearings constituting the offset shaft passes through a neutral position where the yawing moments acting on the offset shaft slider cancel each other. 9. A distance between the slider centers, or a distance between the welding tool and the slider center of one of the linear guide bearings constituting the offset shaft is set. The friction stir welding apparatus according to 1. The distance between the centers of the sliders is Ls, the inclination angle of the center axis of the welding tool with respect to the axis of the pressure axis is α, the applied pressure acting as a reaction force on the welding tool is F, and the welding tool from the slider center of the offset shaft When the distance to the tip of Dt is Dt, the offset load that is the resistance when moving the offset shaft is Fy, and the offset distance is Sy,
Ls≈Dt × Fy / (F × cos α) −Sy / 2
The friction stir welding apparatus according to claim 8 or 9, characterized in that:   The friction stir welding apparatus according to any one of claims 8 to 10, wherein the center axis of the welding tool and the position of the axis of a turning axis motor that rotates the welding tool are shifted from each other.   By inserting an inclination imparting member between a spindle holding the joining tool and a turning axis bracket to which the turning axis motor is attached, and the two-axis drive unit, the center axis of the joining tool is set to the pressure axis. The friction stir welding apparatus according to claim 11, wherein the friction stir welding apparatus is inclined with respect to an axis.

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