JP2006150389A - Friction stir welding method - Google Patents

Abstract

The present invention provides friction stir welding of laminated portions to improve the appearance and ensure the bonding strength.
A laminated part is formed by interposing a perforated work between a first work and a second work. The probe 24 of the friction stir welding tool 20 is embedded in the second workpiece 14 which is the uppermost layer while rotating, passes through the through hole 18 of the perforated workpiece 16 and the through hole in the first workpiece 12 (lowermost layer). 18 reaches the upper end surface exposed to 18. Along with this, the meat of the second workpiece 14 plastically flows and adheres to the through hole 18, and is agitated and mixed integrally with the meat of the upper end surface of the first workpiece 12 by the rotating probe 24.
[Selection] Figure 2

Description

  The present invention relates to a friction stir welding method for friction stir welding of a laminated portion in which a perforated work having a through hole is interposed.

  As one of the measures for improving the fuel consumption, a reduction in the weight of a vehicle body is being attempted. In order to reduce the weight, it has been studied to replace the material such as the outer plate of the vehicle body with an aluminum material having a specific gravity smaller than that of a conventional steel material.

  By the way, as a material for the frame and the inner plate, a steel material is generally selected in order to ensure strength with a small size. In such a case, it is necessary to join different types of metal materials such as a steel material and an aluminum material, and as a joining method therefor, a probe that rotates at high speed is brought into sliding contact with the workpiece, and the frictional heat generated at that time causes the Attention has been focused on friction stir welding in which the flesh of a workpiece is plastically flowed (see, for example, Patent Document 1). Friction stir welding, for example, when compared with arc welding, can suppress the temperature rise of the workpiece, so there is almost no distortion of the workpiece after welding, and it is not necessary to generate an arc, and it is low cost. Since there is no formation of a weld bead, there are advantages such as good appearance.

  However, in the friction stir welding, when a high melting point metal such as a steel material is a workpiece, it is difficult to plastically flow the meat of the workpiece. Therefore, it is not easy to employ the friction stir welding. In addition, it is necessary to use a friction stir welding tool having a probe with extremely excellent heat resistance, which is disadvantageous in terms of cost.

  Further, in the technique described in Patent Document 1, as shown in FIG. 5 of Patent Document 1, only the uppermost layer and the intermediate layer are bonded, and the uppermost layer and the lowermost layer are not bonded. For this reason, there is a concern that sufficient bonding strength is not ensured in the laminated portion.

  In order to eliminate such inconvenience, Patent Document 2 discloses that a workpiece is laminated on a perforated workpiece provided with a through hole to form a laminated portion, and a friction stir welding tool is formed from the workpiece side of the laminated portion. It is proposed that the probe is buried to cause the flesh of the workpiece to plastically flow and harden after the diameter of the flesh protruding from the through hole is greatly expanded compared to the through hole. That is, in this case, the hardened meat protruding from the through hole is used as a retainer, and thereby the perforated work and the work are joined together.

  Also, in Patent Document 3, friction stir welding is performed on a laminated portion composed of three or more layers formed by interposing an intermediate layer made of a refractory metal material between the uppermost layer and the lowermost layer, which are low melting point metals. At this time, it has been proposed to break the intermediate layer (refractory metal material) with a probe and to perform friction stir welding between the uppermost layer and the lowermost layer.

JP 2004-167525 A JP 2004-148320 A Japanese Patent Laid-Open No. 10-71479

  However, the technique described in Patent Document 2 has a problem in that the appearance is impaired because the retaining meat protrudes.

  On the other hand, in the technique described in Patent Document 3, since the intermediate layer is broken with a probe, the probe is worn out at an early stage. Furthermore, when an intermediate layer made of a hard material such as steel is to be broken with a probe, the intermediate layer is deformed in a wave shape, which may cause a gap between the intermediate layer and the lowermost layer or the uppermost layer. is there. Moreover, since a through hole having a diameter substantially the same as that of the probe is formed in the intermediate layer, there is a concern that the meat of the uppermost layer and the lowermost layer cannot be sufficiently stirred. In this case, the bonding strength cannot be ensured.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a friction stir welding method capable of providing a laminated portion having good appearance and sufficient bonding strength.

In order to achieve the above-described object, the present invention frictionally rubs a laminated part formed by interposing at least one perforated work provided with a through hole between a first layer and a second layer. A friction stir welding method for stir welding,
Using a friction stir welding tool having a probe of a size that causes play when inserted into the through hole,
The probe buried from the uppermost layer is allowed to pass through the through hole and reach the end surface on the side exposed at the through hole in the lowermost layer,
The meat of the uppermost layer is plastically flowed by the rotation of the probe, and the meat is joined to the meat of the end surface on the side exposed in the through hole in the lowermost layer.

  In the present invention, the uppermost layer meat is bonded over the entire inner wall of the through hole, and the uppermost layer and the lowermost layer are integrally fused, so that sufficient bonding strength is ensured.

  Further, since the probe is passed through the through hole of the perforated work, it is not necessary to break the perforated work with the probe. For this reason, it is possible to avoid wear of the probe 24 by breaking the perforated workpiece. In addition, since the perforated work is not deformed in a wave shape, no gap is generated between the perforated work and the first layer or the second layer.

  Furthermore, according to the present invention, the laminated portion can be joined without forming the protruding portion, so that a product with a good appearance can be obtained.

  Here, the first layer and the second layer constituting the laminated portion may be separate members, or may be portions facing each other while being separated from each other by bending the member. That is, the friction stir welding may be performed by using different portions of the same member as the first layer and the second layer, respectively. In this case, a perforated work may be inserted between the spaced apart parts.

  In the present invention, the perforated work and the work constituting the first layer and the second layer may be made of the same material, but may be made of different materials. That is, according to the present invention, even members made of different materials can be joined. The material of the perforated workpiece is not limited to metal, and may be ceramic or plastic.

  When the material of the perforated work and the work constituting the first layer and the second layer is, for example, different metals, suitable materials for the perforated work include iron or an iron-based alloy, As a suitable material for the workpiece, aluminum or an aluminum-based alloy can be used.

  According to the present invention, a laminated portion is provided with a perforated work interposed therebetween, and the probe of the friction stir welding tool is passed through the through hole of the perforated work. Along with this, the plastically flowed uppermost layer meat is joined to the inner wall of the through hole, and the lowermost layer meat is integrally friction stir welded, so that lamination with excellent bonding strength without breaking the perforated workpiece Part can be obtained.

  And since meat | flesh does not protrude from a through-hole, the obtained laminated part has a favorable external appearance.

  Preferred embodiments of the friction stir welding method according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows a longitudinal section of a laminated portion 10 composed of three layers. In the laminated portion 10, a space between a first work 12 made of so-called 6000 series aluminum having a JIS symbol number of the 6000 series and a second work 14 made of 6000 series aluminum as in the case of the first work 12. In addition, a perforated work 16 made of steel is interposed. That is, in this laminated part 10, the 1st workpiece | work 12 which is a 1st layer is a lowermost layer, the perforated workpiece | work 16 is an intermediate | middle layer, and the 2nd workpiece | work 14 which is a 2nd layer is an uppermost layer.

  The laminated portion 10 is provided by laminating the first work 12, the perforated work 16, and the second work 14 in this order. Of course, in this case, the laminated part 10 is laminated so that the portion of the perforated workpiece 16 provided with the through hole 18 is included in the laminated part 10.

  The thicknesses of the first workpiece 12, the second workpiece 14, and the perforated workpiece 16 are set to T1, T2, and T3, respectively. The diameter of the through hole 18 formed in the perforated workpiece 16 is set to D1.

  As shown in FIG. 1, a friction stir welding tool 20 for integrating the laminated portion 10 by friction stir welding is connected to a rotating body 22 and one end of the rotating body 22 so that the tip is conical. The probe 24 is curved.

Here, as the probe 24, the diameter D2 is smaller than the diameter D1 of the through hole 18, and the length L1 is the thickness T2 of the second workpiece 14 (uppermost layer) and the thickness of the perforated workpiece 16. A thickness that exceeds the total thickness of T3 and is less than the thickness of the laminated portion 10 is selected. In other words, a probe 24 that satisfies the following conditional expressions (1) and (2) at the same time is selected in advance.
D2 <D1 (1)
T2 + T3 <L1 <T1 + T2 + T3 (2)

  For example, D1 may be set to D2 + 2 mm. Moreover, L1 should just be made into the grade which deducted 0.5 mm from T1 + T2 + T3, for example.

  The friction stir welding method according to the present embodiment is performed on the laminated portion 10 as follows using the friction stir welding tool 20 having such a probe 24.

  First, as shown in FIG. 1, the friction stir welding tool 20 is arranged on the laminated portion 10 placed on a support base (not shown) so that the axis thereof substantially coincides with the axis of the through hole 18. Thereby, the probe 24 is positioned above the through hole 18.

  Next, after the friction stir welding tool 20 is lowered to a position separated from the laminated portion 10 by a predetermined distance, the probe 24 is urged to rotate together with the rotating body 22, and in this state, the uppermost layer (second The probe 24 is brought into sliding contact with the upper end surface of the work 14). When frictional heat is generated along with the sliding contact, the contact portion of the probe 24 on the second workpiece 14 and the vicinity thereof are softened. When this softening further proceeds, as shown in FIG. 2, the probe 24 is buried in the second workpiece 14, and the softened meat of the second workpiece 14 corresponding to this buried is the through hole 18 of the perforated workpiece 16. Flow into. Since the diameter D1 of the through hole 18 is larger than the diameter D2 of the probe 24, this inflow easily proceeds. A part of the meat of the second workpiece 14 that has flowed into the through hole 18 adheres to the inner peripheral wall of the through hole 18.

  As described above, the length L1 of the probe 24 is larger than T2 + T3 (total thickness of the second workpiece 14 and the perforated workpiece 16) and smaller than T1 + T2 + T3 (thickness of the stacked portion 10). For this reason, the probe 24 passes through the through hole 18 and reaches the upper end surface of the first workpiece 12 (lowermost layer) exposed in the through hole 18. Along with this, the remaining part of the second work 14 that has flowed into the through hole 18 is lowered while being pushed by the probe 24, and finally the first work 12 together with the probe 24 is lowered. Reach the top surface.

  The probe 24 that has reached the upper end surface of the first workpiece 12 is brought into sliding contact with the upper end surface to soften the upper end surface. Thereby, the meat of the upper end surface of the first workpiece 12 and the meat of the second workpiece 14 that has reached the upper end surface are integrally agitated and mixed by the probe 24 that rotates, and eventually both of the meat flow plastically. Is done. At this time, the length L1 of the probe 24 is set to be smaller than the thickness of the stacked portion 10 and a part of the thickness of the second workpiece 14 adheres to the inner peripheral wall of the through hole 18. The meat will not protrude.

  After the predetermined time has passed after stirring the meat of the second workpiece 14 (uppermost layer) and the first workpiece 12 (lowermost layer) in this way, as shown in FIG. 3, a friction stir welding tool 20 is displaced upward, and the probe 24 is separated from the laminated portion 10. As the stirring is completed, frictional heat is no longer generated, and the plastic fluidized meat is cured by natural cooling. As a result, the cooled and hardened second workpiece 14 is joined to the inner peripheral wall of the through-hole 18, and is joined to the integrally stirred and mixed first workpiece 12, thereby joining the laminated portion 10. To.

  In the laminated part 10 joined in this way, the thickness of the second work 14 is joined over the entire inner peripheral wall of the through hole 18, and the second work 14 and the first work 12 are joined together. High bonding strength is ensured.

  Moreover, according to this Embodiment, it is not necessary to fracture | rupture the perforated workpiece | work 16 which is steel materials with the probe 24, Therefore, the probe 24 does not wear with the fracture | rupture of the perforated workpiece | work 16. FIG. For this reason, the lifetime of the probe 24 can be prolonged. In addition, in this case, since the perforated work 16 is not deformed in a wave shape, a gap is generated between the first work 12 and the perforated work 16 or between the perforated work 16 and the second work 14. Nor.

  Further, since the perforated workpiece 16 is not plastically flowed, it is not necessary to prepare a probe having excellent heat resistance. For this reason, it is advantageous in terms of cost.

  Furthermore, according to the present embodiment, all of the softening of the meat of the second workpiece 14, the plastic flow to the first workpiece 12 through the through-holes 18 of the meat, and the joining are all performed in one step. Work efficiency can be improved.

  In addition, as described above, in the present embodiment, the stacked portion 10 can be joined without forming the protruding portion. For this reason, the product with a favorable external appearance can be obtained by making the 1st workpiece | work 12 side into the outer surface visually recognized by a user.

  When the burr 28 is formed, the laminated portion 10 is subjected to a finishing process for removing the burr 28 by cutting.

  In the above-described embodiment, only one perforated workpiece 16 is interposed to provide the laminated portion 10, but it goes without saying that two or more may be interposed. In this case, the perforated workpieces 16 may be stacked so that the through holes 18 communicate with each other.

  The material of the perforated workpiece 16 may be aluminum.

  Next, the case where the laminated portion 30 shown in FIG. 4 is friction stir welded will be described.

  In this case, the perforated work is an inner panel 32 constituting a door panel of the automobile. And the laminated part 30 is formed by interposing the site | part in which the through-hole 34 in this inner panel 32 was provided between the site | parts mutually opposed when the outer panel 36 was bent.

  That is, in this embodiment, the lowermost layer and the uppermost layer are different parts of the outer panel 36 (the same member). In the following description, a portion of the outer panel 36 located below the inner panel 32 in FIG. 4 is referred to as a first layer, and its reference numeral is 38, and is located above the inner panel 32. The part to be performed is denoted as the second layer, and its reference numeral is 40.

  The inner panel 32 is made of steel, and the wall thickness T6 is normally set to 0.5 to 1.5 mm. On the other hand, the outer panel 36 is generally made of aluminum, and the wall thickness is generally set to 1 to 1.5 mm. That is, the thicknesses T4 and T5 of the first layer 38 and the second layer 40 are generally 1 to 1.5 mm.

  The laminated portion 30 is formed by performing a so-called hemming process in which the end portion of the outer panel 36 is bent so as to surround the end portion of the inner panel 32 at the end portion.

As the friction stir welding tool 20 for integrating the laminated portion 30 by friction stir welding, a tool in which the probe 24 satisfies the same conditions as described above is selected. That is, the diameter D2 of the probe 24 is set smaller than the diameter D3 of the through hole. Further, the length L1 is selected so as to exceed the total thickness of the thickness T5 of the second layer 40 (uppermost layer) and the thickness T6 of the inner panel 32 and less than the thickness of the laminated portion 30. . In other words, as the probe 24, one that satisfies the following conditional expressions (3) and (4) is selected in advance.
D2 <D3 (3)
T5 + T6 <L1 <T4 + T5 + T6 (4)

  For example, D3 may be set to D2 + 2 mm. Moreover, L1 should just be made into the grade which deducted 0.5 mm from T4 + T5 + T6, for example.

  Thereafter, the same operation as described above may be performed. That is, after the friction stir welding tool 20 is lowered to a position separated from the laminated portion 10 by a predetermined distance, the rotating body 22 is rotationally biased, and in this state, the uppermost layer (second layer 40) of the laminated portion 30 is placed. The probe 24 is brought into sliding contact with the upper end surface. When the meat of the second layer 40 is softened, as shown in FIG. 5, the probe 24 is buried in the second layer 40 and the softened meat of the second layer 40 flows into the through hole 34 of the inner panel 32. Part of the meat of the second layer 40 that has flowed into the through hole 34 adheres to the inner peripheral wall of the through hole 34.

  On the other hand, the probe 24 passes through the through hole 34 and reaches the upper end surface of the first layer 38 (lowermost layer) exposed in the through hole 34. Accordingly, a part of the meat of the second layer 40 that has flowed into the through hole 34 reaches the upper end surface of the first layer 38.

  Thereafter, similarly to the above, the flesh of the upper end surface of the first layer 38 and the flesh of the second layer 40 that has reached the upper end surface are integrally stirred and mixed by the probe 24 that rotates. In other words, both meats are plastically flowed.

  After the predetermined time has elapsed, as shown in FIG. 6, the friction stir welding tool 20 is displaced upward to separate the probe 24 from the laminated portion 30. If the plastic-flowed meat is cured by natural cooling, the meat of the second layer 40 is joined to the inner peripheral wall of the through-hole 34 and is joined to the meat of the first layer 38 that is integrally stirred and mixed. Part 30 is joined. In this case, the first layer 38 side may be a visible outer surface. When the burr 28 is formed, the burr 28 may be removed by finishing.

  Of course, also in this case, the same effect as the case where the laminated part 10 is joined is acquired. It goes without saying that a plurality of inner panels 32 may be laminated.

  And as long as sufficient strength is ensured, the inner panel 32 may be made of aluminum in the same manner as the outer panel 36.

  In any of the above-described embodiments, the through holes 18 and 34 do not need to have a perfect circular shape, and may have dimensions that allow play when the probe 24 is inserted into the through holes 18 and 34. The shape may be elliptical or polygonal.

  Further, it is not particularly necessary that L1 satisfies the conditional expression (2). Even in this case, the first workpiece 12 and the second workpiece 14 can be joined.

It is a partial longitudinal cross-section explanatory drawing which shows the longitudinal cross-section of a laminated part, and the principal part of the tool for friction stir welding. It is a partial longitudinal cross-sectional enlarged view which shows the state by which the probe of the friction stir welding tool was buried in the laminated part of FIG. It is a partial longitudinal cross-sectional enlarged view which shows the laminated part joined by the friction stirring method which concerns on this Embodiment. It is a partial longitudinal cross-sectional enlarged view which shows the longitudinal cross-section of the laminated part of another form, and the principal part of the tool for friction stir welding. It is a partial longitudinal cross-sectional enlarged view which shows the state by which the probe of the friction stir welding tool was buried in the laminated part of FIG. It is a partial longitudinal cross-sectional enlarged view which shows the laminated part joined by the friction stirring method which concerns on this Embodiment.

Explanation of symbols

10, 30 ... Laminated part 12 ... First work (first layer)
DESCRIPTION OF SYMBOLS 14 ... 2nd workpiece | work (2nd layer) 16 ... Perforated work 18, 34 ... Through-hole 20 ... Friction stir welding tool 24 ... Probe 32 ... Inner panel (perforated work)
36 ... Outer panel 38 ... 1st layer 40 ... 2nd layer D1, D2, D3 ... Diameter L1 ... Length T1, T2, T3, T4, T5, T6 ... Thickness

Claims (3)

A friction stir welding method for friction stir welding a laminated portion formed by interposing at least one perforated work provided with a through hole between a first layer and a second layer,
Using a friction stir welding tool having a probe of a size that causes play when inserted into the through hole,
The probe buried from the uppermost layer is allowed to pass through the through hole and reach the end surface on the side exposed at the through hole in the lowermost layer,
A friction stir welding method, wherein the meat of the uppermost layer is plastically flowed by the rotation of the probe, and the meat is joined to the meat of the end surface of the lowermost layer exposed to the through hole.   2. The friction stir welding method according to claim 1, wherein the first layer and the second layer are formed by using parts that are separated from each other by bending a member, and between the separated parts. A friction stir welding method comprising inserting a perforated workpiece.   3. The friction stir welding method according to claim 1, wherein the perforated work is selected from materials different from the work constituting the first layer and the second layer. 4. .

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