JP2007075839A - Aluminum structure and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high accuracy in bending position by ensuring that a bending center is in a weld zone, in manufacturing an aluminum structure by performing friction stir welding between aluminum plates and then bending the weld zone along the longitudinal direction. <P>SOLUTION: When a region of a width W comprising a weld zone 6 and a HAZ (heat affected zone) 7 on both sides thereof is viewed, a difference in level is formed, with a plate thickness difference existing in the width direction, wherein a plate thickness T2 on the outside in the width direction including the HAZ 7 is formed thicker than the plate thickness T1 on the inside. The HAZ 7 is softened compared with the weld zone 6 or a non-heat affected zone. However, since the HAZ 7 is formed thicker, it becomes no starting point for deformation at the time of bending, making bending possible with the weld zone 6 as the center of bending. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aluminum structure manufactured by bending a plurality of aluminum plates after friction stir welding and a method for manufacturing the same.

  As shown in FIG. 6, the ends of the two aluminum plates 1 and 2 are butted together (FIG. 6 (a)), and the butted parts are welded by arc welding or the like to form the joining plate 3 (FIG. 6 (b)). After welding, if bending is performed at the butt portion (center position of the bead 4), the bead 4 portion becomes a cast structure, so that it is not substantially deformed, and the HAZ (heat affected zone) 5 and 5 on both sides thereof are Since it is softened, bending deformation proceeds from that point, and as a result, as shown in FIG. 6 (c), it does not bend at the abutting portion but bends around the HAZ5 portion, and high bending position accuracy is obtained. I can't.

On the other hand, as shown in FIG. 7, the ends of the two aluminum plates 1 and 2 are butted together (FIG. 7 (a)), and the butted portion is friction stir welded to form the joining plate 3 (FIG. 7 (b)). After the joining, when bending is performed at the butt portion (center position of the joining portion 6), since the HAZ (heat affected zone) 7 and 7 on both sides of the joining portion 6 are softened, the bending work is started from there. As a result, as shown in FIG. 7 (c), it does not bend at the center of the joining plate 3, but bends around the HAZ7 portion, and high bending position accuracy cannot be obtained. However, since the width of the joint 6 and the HAZ 7 of the friction stir welding can be made smaller than that of arc welding, the bending position accuracy is improved as compared with the case of arc welding.
Non-Patent Document 1 and Patent Documents 1 and 2 below describe press-molding a plate that has been bent or joined at a joint portion after friction stir welding of an aluminum plate or a magnesium plate.

WELDING JOURNAL 1996 March 41-45 "Friction Stir Process Welds Aluminum Alloys" JP 2004-176149 A JP-A-2005-125341

  As shown in FIG. 7 (a), in friction stir welding, the aluminum plates 1 and 2 are abutted and fixed on the surface plate 8, the rotary tool 9 is pressed against the aluminum plates 1 and 2, and the probe 11 at the tip is abutted. It is carried out by inserting it into the part and moving it along the butt part. The aluminum is heated and plastically flows (stirred) by the frictional heat generated by the rotation of the rotary tool 9, and the butt portion is joined by intermingling the structure of the part. The joint portion 6 is a portion in which aluminum is plastically flowed and stirred, and crystal grains are refined. The HAZs 7 on both sides are affected by the heat from the joint 6 and are softer than the parts of the base 6 (non-heat affected part) outside the joint 6 and the HAZ 7.

When the friction stir welded aluminum plate 3 is bent at or near the butt portion, the joint 6 exhibits an elongation comparable to that of the base metal, unlike the arc weld bead 4, and the crystal grains are miniaturized. It is advantageous for suppressing cracking, and it is desirable that the bending center can be surely brought to the joint portion 6 so that bending can be performed with high accuracy. However, conventionally, even if bending is performed with the butt portion as the center of bending, the softened HAZ 7 is likely to be the starting point of bending as shown in FIG. 7C, and high bending position accuracy could not be obtained. .
Accordingly, an object of the present invention is to achieve a high bending position accuracy by allowing an aluminum plate subjected to friction stir welding to be bent so that the bending center comes to the joint.

The present invention is an aluminum structure in which the first and second aluminum plates are butted at ends, friction stir welded along the straight butted portion, and the joint is bent along the longitudinal direction. There is a difference in plate thickness in the width direction when a region having a predetermined width composed of the joint portion and the heat affected zone on both sides thereof is seen, and the plate thickness on the outer side in the width direction including the heat affected zone is thicker than the inner plate thickness in the region. It is characterized by being.
More specifically, in the above aluminum structure, the thickness difference in the width direction is continuously changed when the difference in level is due to a level difference (the thickness outside the level difference is formed thicker than the thickness inside). In the case (the plate is thicker toward the outside in the region). Moreover, the said aluminum structure includes the case where the said 1st or / and 2nd aluminum plate is a part of aluminum extrusion material. The aluminum extruded material is a double skin panel material composed of, for example, parallel flange plates on both sides and ribs connecting between them.
In the present invention, aluminum includes an aluminum alloy. As the aluminum alloy, JIS 5000 series, 6000 series, 7000 series and the like can be suitably used. When the aluminum alloy is a heat treatment type alloy, the heat treatment can be performed at an appropriate time, for example, T1 treatment material is subjected to T5 treatment after friction stir welding and bending, or T5 treatment material is subjected to friction stir welding and bending.

  The method for obtaining the aluminum structure includes: an aluminum structure in which the first and second aluminum plates are abutted, friction stir welded along the straight abutting portion, and the joint portion is bent along the longitudinal direction. In the manufacturing method, the aluminum structure has a plate thickness difference in a width direction when a region having a predetermined width composed of a joint portion formed by friction stir welding and a heat-affected portion on both sides thereof is seen, and in the region, the thermal influence is present. The first and second aluminum plates are formed to have a thickness outside the width direction in the region of the predetermined width centered on the butted portion when they are butted. Is formed thicker than the inner plate thickness. In short, a plate thickness difference in the width direction is formed in advance in a region where the joining portion and the heat affected zone of the aluminum plate are formed.

  The aluminum structure according to the present invention has a plate thickness in the width direction when a region having a predetermined width (joint portion and heat-affected portions on both sides) in the vicinity of the butted portion of the first and second aluminum plates subjected to friction stir welding is observed. A difference is formed, and the plate thickness on the outer side in the width direction including the heat affected zone is formed thicker than the plate thickness on the inner side. In other words, in the said area | region, the board | plate thickness of the softened heat affected zone is formed thicker than the junction part inside. Therefore, when bending with the butt portion as the bending center, it is difficult to bend at the heat affected zone as in the past, and the butt portion or its vicinity (joined portion) can be bent as planned to achieve high bending position accuracy. can do. The plate thickness of the heat affected zone is appropriately set in consideration of the softening level of the aluminum alloy so that this does not become the starting point of deformation due to bending.

  In the present invention, the end portions of the first and second aluminum plates are brought into contact with each other and subjected to friction stir welding, and after the joining, the joined portion is bent into a desired shape. Therefore, even if the joint portion is located at a corner portion or a curved portion of the aluminum structure, the friction stir welding itself can be performed in a state in which the end portions of the flange plates are flat, and the aluminum plates are joined together. Is easy to position.

Hereinafter, the present invention will be described more specifically with reference to FIGS.
Fig.1 (a)-(c) is an example of the manufacturing method of this invention. The same parts as those in FIG. 7 are given the same numbers.
As shown in FIG. 1 (a), the first and second aluminum plates 1 and 2 are fixed on the surface plate 8 with their ends butted together, and the rotary tool 9 is pressed against the aluminum plates 1 and 2, The probe 11 at the tip is inserted into the abutting portion and moved linearly (perpendicular to the paper surface of FIG. 1) along the abutting portion to perform friction stir welding. The aluminum plates 1 and 2 are formed with a thick portion 12 having a thick plate thickness at a predetermined distance from the butted portion. In the width region R (the same width as the following region W), the plate thickness on the outer side in the width direction is formed thicker than the plate thickness on the inner side. In other words, each of the aluminum plates 1 and 2 is formed with a thin wall in the vicinity of the butt end and a thick wall at a distance from it. The aluminum plates 1 and 2 are made of an extruded material, but may be made of a differential thickness rolled material.

FIG. 1B shows the joining plate 3 after the friction stir welding, and heat affected portions (hereinafter referred to as HAZ) 7 having a width W2 are formed on both sides of the joining portion 6 having a width W1. The width W1 is the maximum width of the joint 6 and the width W2 is the width of the HAZ 7 formed outside the joint 6 having the width W1.
Looking at the region of width W (= W1 + 2W2) consisting of the joint 6 and HAZ7, a step is formed in the lower surface width direction and there is a difference in plate thickness, and the plate thickness T2 on the outer side in the width direction (outside the step) including HAZ7 is , Thicker than the plate thickness T1 on the inside (inside the step). In this example, the central portion of the joint portion 6 having the width W1 is formed in the portion of the plate thickness T1, and part (both ends) of the joint portion 6 and the HAZ 7 having the width W2 are formed in the portion of the plate thickness T2.

FIG. 1C shows the joining plate 3 bent with the center of the joining portion 6 (original butted portion) as the bending center. Since the softened HAZ 7 having the width W2 is formed in a thick portion, it is possible to suppress preferential deformation as in the prior art during bending, and the center of the joint 6 is set to the center of the joint 6 as a bending center. Bending can be performed with high bending position accuracy.
In this example, bending is performed so that the side on which the friction stir welding is performed (the side on which the rotary tool 9 is pressed) is on the outside of the bending, but the side on which the friction stir welding is performed is on the inside of the bending. Bending can also be performed. This is the same in the following examples.

2A to 2C are other examples of the production method of the present invention. The same parts as those in FIG. 1 are given the same numbers.
The difference from the manufacturing method of FIG. 1 is that only the vicinity of the abutting portion of the first and second aluminum plates 1 and 2 is thin, a step is formed on the upper surface of the plate, and the rotary tool 9 is formed near the abutting portion. It is a point inserted in the recessed part 13 made.
FIG. 2B shows the joining plate 3 after the friction stir welding, and HAZs 7 having a width W2 are formed on both sides of the joining part 6 having a width W1. Looking at the region of width W (= W1 + 2W2) consisting of the joint 6 and HAZ7, a step is formed in the width direction and there is a difference in plate thickness, and the plate thickness T2 on the outside in the width direction (outside the step) where HAZ7 is formed Is thicker than the plate thickness T1 on the inner side (the inner side of the step). In this example, the HAZ 7 having the width W2 is formed in the portion having the plate thickness T2, and the joint portion 6 having the width W1 is formed in the portion having the plate thickness T1.
In the example of FIG. 1, irregularities corresponding to the step of the plate are formed on the upper surface of the surface plate. However, in the example of FIG. 2, the step is formed on the upper surface of the plate, and the lower surface of the plate is flat. A flat surface plate can be used. The same applies to the example shown in FIG.

  FIG. 2C shows the joining plate 3 bent with the center of the joining portion 6 (original butted portion) as the bending center. Since the softened HAZ 7 having the width W2 is formed in a thick portion, it is possible to suppress preferential deformation as in the prior art during bending, and the center of the joint 6 is set to the center of the joint 6 as a bending center. Bending can be performed with high bending position accuracy.

3A and 3B are other examples of the production method of the present invention. The same parts as those in FIG. 1 are given the same numbers.
The difference from the manufacturing method of FIG. 1 is that an inclined portion 14 is formed in the vicinity of the lower surface abutting portion of the first and second aluminum plates 1 and 2, and the thickness is continuously reduced toward the abutting portion. It is.
FIG. 3B shows the joining plate 3 after the friction stir welding, and HAZs 7 having a width W2 are formed on both sides of the joining part 6 having a width W1. Looking at the region of width W (= W1 + 2W2) consisting of the joint 6 and HAZ7, there is a difference in plate thickness due to a continuous change in plate thickness in the width direction, and the width in which HAZ7 is formed by this change in plate thickness. The plate thickness on the outer side in the direction is formed thicker than the plate thickness on the inner side.

  When this joining plate 3 is bent with the center of the joining portion 6 (original butted portion) as the bending center, the softened HAZ 7 having the width W2 is formed in a relatively thick portion of the plate thickness. It is possible to suppress deformation preferentially as in the prior art, and the bonding plate 3 can be bent with high bending position accuracy with the center of the bonding portion 6 as the center of bending.

4A and 4B show another example of the production method of the present invention. The same parts as those in FIG. 1 are given the same numbers.
The difference from the manufacturing method of FIG. 1 is that the first and second aluminum plates 1 and 2 do not have a thick portion, and the whole is a uniform thick plate, and the cylindrical portion of the rotary tool 9 Friction stir welding is performed in a state where the aluminum plates 1 and 2 are pushed into the aluminum plates 1 and 2 by a predetermined thickness (T2-T1). In addition, although the aluminum excluded by pushing in the cylindrical part of the rotary tool 9 remains as a burr | flash along the junction part 6, this is removed after friction stir welding.
FIG. 2B shows the joining plate 3 after the friction stir welding, and HAZs 7 having a width W2 are formed on both sides of the joining part 6 having a width W1. Looking at the region of width W (= W1 + 2W2) consisting of the joint 6 and HAZ7, a step is formed in the width direction and there is a difference in plate thickness, and a plate thickness T2 on the outer side in the width direction (outside the step) where HAZ7 is formed. Is thicker than the plate thickness T1 on the inner side (the inner side of the step). In this example, HAZ is formed in a portion having a plate thickness T2, and the joint portion 6 is formed in a portion having a plate thickness T1.

  When this joining plate 3 is bent with the center of the joining portion 6 (original butted portion) as the bending center, the softened HAZ 7 having the width W2 is formed in a relatively thick portion of the plate thickness. It is possible to suppress deformation preferentially as in the prior art, and the bonding plate 3 can be bent with high bending position accuracy with the center of the bonding portion 6 as the center of bending.

  FIGS. 5A to 5C show examples in which the present invention is applied to an extruded material. As shown in FIG. 5A, the extruded materials 15 and 16 to be joined connect the flange plates 15a, 15b, 16a, and 16b on both sides that are parallel to each other and the flange plates 15a, 15b, 16a, and 16b, respectively. This is a double skin panel composed of a plurality of ribs 15c, 16c. The flange plate 15a of the extruded material 15 and the flange plate 16a of the extruded material 16 are abutted and friction stir welded. Note that the end portions of the flange plates 15a and 16a are thicker from a position away from the abutting portion by a predetermined distance, and when viewed in the butted state as shown in FIG. 5A, a predetermined width centered on the abutting portion. In the region R (the same width as the region W below), the plate thickness on the outer side in the width direction is formed thicker than the plate thickness on the inner side.

FIG. 5B shows the joining member 17 after the friction stir welding, and HAZs 19 having a width W2 are formed on both sides of the joining portion 18 having a width W1. The width W1 is the maximum width of the joint 18 and the width W2 is the width of the HAZ 19 formed outside the joint 18 having the width W1.
Looking at the region of the width W (= W1 + 2W2) consisting of the joint 18 and the HAZ 19, there is a difference in the plate thickness in the lower surface width direction, and the plate thickness T2 on the outer side in the width direction (outside the step) including the HAZ 19 is , Thicker than the plate thickness T1 on the inside (inside the step). In this example, the central portion of the joint portion 6 having the width W1 is formed in the portion of the plate thickness T1, and part (both ends) of the joint portion 6 and the HAZ 7 having the width W2 are formed in the portion of the plate thickness T2.

  FIG. 5C shows the joining member 17 bent with the center of the joining portion 18 (original butted portion) as the bending center. Since the softened HAZ 19 having the width W2 is formed in a thick portion, it can be prevented from being preferentially deformed as in the prior art during bending, and the joining member 17 is set to have the center of the joining portion 18 as the bending center. Bending can be performed with high bending position accuracy.

A structure in which such a double skin panel is joined is suitable when the entire structure needs to be uniform in strength, such as an energy absorbing member that absorbs collision energy (so-called crushable member). .
When such a structure is manufactured by, for example, arc welding a plurality of extruded profiles, the bead is a cast structure, and the HAZ (heat affected zone) on both sides thereof is softened. Uneven portions are formed and deformation at the time of collision is not stable. For this reason, the structure must be annealed after welding to form O material, and the entire material must be homogenized. Then, the strength of the structure is lowered, and in order to absorb a predetermined energy, it is necessary to enlarge the structure or increase the number of the structures. On the other hand, when all the joints of the structure are friction stir welded, the non-uniformity of strength is small, so use without treatment with O material (if it is heat treated aluminum alloy, use T5 material) Is possible. Since the T5 material has high strength, the structure can be downsized or thinned, or the number thereof can be reduced.

It is a schematic diagram explaining the manufacturing method of the aluminum structure which concerns on this invention. It is another schematic diagram explaining the manufacturing method of the aluminum structure which concerns on this invention. It is another schematic diagram explaining the manufacturing method of the aluminum structure which concerns on this invention. It is another schematic diagram explaining the manufacturing method of the aluminum structure which concerns on this invention. It is another schematic diagram explaining the manufacturing method of the aluminum structure which concerns on this invention. It is a schematic diagram which shows the manufacturing method of the aluminum structure of the comparative example joined by arc welding, and the state at the time of bending deformation. It is a schematic diagram which shows the manufacturing method of the aluminum structure of the comparative example joined by the conventional friction stir welding, and the state at the time of bending deformation.

Explanation of symbols

1, 2, 15a, 16a Aluminum plate 3,17 Joint 6,18 Joint part of friction stir welding 7,19 HAZ (heat affected zone) of friction stir welding
8 Surface plate 9 Rotating tool 15, 16 Extruded material

Claims (5)

In the aluminum structure in which the first and second aluminum plates are butted at ends, friction stir welded along the straight butted portion, and the joint is bent along the longitudinal direction. There is a difference in plate thickness in the width direction when a region having a predetermined width composed of the heat affected zone on both sides is seen, and the plate thickness on the outer side in the width direction including the heat affected zone is thicker than the inner plate thickness in the region. An aluminum structure characterized by that. The aluminum structure according to claim 1, wherein a step is formed in the region, and a plate thickness outside the step is formed thicker than a plate thickness inside. The aluminum structure according to claim 1, wherein the thickness of the region continuously changes in the region. The said 1st or / and 2nd aluminum plate is a part of aluminum extrusion material, The aluminum structure described in any one of Claims 1-3 characterized by the above-mentioned. In the manufacturing method of an aluminum structure in which the first and second aluminum plates are butted, friction stir welded along the straight butted portion, and the joint is bent along the longitudinal direction, the aluminum structure is a friction There is a difference in plate thickness in the width direction when a region having a predetermined width composed of a joint formed by stir welding and heat-affected portions on both sides thereof is seen, and in the region, the plate thickness on the outer side in the width direction including the heat-affected portion is on the inner side. The first and second aluminum plates are formed so that the outer thickness in the width direction is thicker than the inner thickness in the region of the predetermined width centered on the butted portion when they are butted. A method for producing an aluminum structure, comprising:

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