JP6721451B2 - Member processing method and member joining method - Google Patents

Description

The present invention relates to a member processing method and a member joining method.

In order to reduce the weight and improve the safety of automobiles, a metal with low specific gravity and high strength called high tension steel is used. High tension steel is effective for weight reduction and safety improvement, but it is heavier than low specific gravity materials such as aluminum. Further, when high tension steel is used, problems such as deterioration of formability, increase of molding load and deterioration of dimensional accuracy occur due to its high strength. In order to solve these problems, in recent years, extrusion-molded products, cast products, and press-molded products that use aluminum having a lower specific gravity than steel have been made into multi-materials that utilize steel parts together. ..

The problem with multi-materials is the joining of dissimilar metals such as steel parts and aluminum parts. For example, Patent Document 1 discloses a joining method of members that enables joining of dissimilar metals in multi-material formation by utilizing an elastic body. In the member joining method of Patent Document 1, the tubular body (first member) is inserted into the through hole of the wall surface body (second member), the elastic body is inserted inside the tubular body, and the elastic body is pressed. The tubular body is expanded and the tubular body and the wall surface body are pressed against each other.

JP-A-51-133170

However, the joining method disclosed in Patent Document 1 does not mention the shape of the joined members, particularly that the joined tubes are polygonal tubes. That is, when the pipes to be joined are polygonal pipes, no consideration is given to the detailed shapes that are preferable for joining, such as being easy to process and suppressing cracks.

An object of the present invention is, in a method of processing a member using an elastic body, to expand and deform the first member while suppressing cracking of the first member.

A method of processing a member according to a first aspect of the present invention is a hollow shape extending in an axial direction, a corner portion having an R portion is provided on an inner peripheral surface of the cross-sectional shape in the axial direction, and a shape of the corner portion. A first member defined by the following formula and an elastic body are prepared, the elastic body is inserted into the first member, and the elastic body is compressed in the axial direction to obtain a diameter of the axis line. Expanding outward in the direction, thereby expanding and deforming the first member.

θ：第１部材の角部の内周面における角度
Ｒ_ｃ：第１部材の角部の内周面のＲ部の半径
Ｌ_１：第１部材の角部を構成する２つの辺部のうち一方の辺部の直線長さ
Ｌ_２：第１部材の角部を構成する２つの辺部のうち他方の辺部の直線長さ
ｎ：第１部材の材料のｎ値（加工硬化指数）
を備える、部材の加工方法を提供する。

theta: angle R _c of the inner peripheral surface of the corner portion of the first _member: radius L ₁ of the R portion of the inner peripheral surface of the corner portion of the first _member: one of the two sides constituting a corner of the first member Linear length L _{2 of} one side: linear length n of the other side of the two sides forming the corner of the first member n: n value of the material of the first member (work hardening index)
A method of processing a member is provided.

In the method for joining members according to the second aspect of the present invention, a second member having a strength different from that of the first member and provided with a hole is further prepared, and the first member is provided in the hole of the second member. Inserting a member, expanding and deforming the first member using the above-described member processing method, and joining the first member and the second member.

According to these methods, the elastic body is expanded outward in the radial direction of the axis to uniformly expand and deform the first member, whereby local deformation can be prevented and the load on each member can be reduced. This is because the first member can be uniformly deformed by utilizing the property that the elastic body compressed in the axial direction expands radially outward of the axis. Therefore, the fitting accuracy of the first member and the second member is improved, and the joint strength can be improved. Further, it is simpler than a joining method in which electromagnetic forming or other processing is performed. Here, the strengths of the first member and the second member refer to general properties related to deformation and fracture of the material such as yield strength, tensile strength, ductility, rigidity, or bending strength. Also, ave(L ₁ , L ₂ ) in the above formula (1) represents the average value of L ₁ and L ₂ , and may be simply referred to as L hereinafter.

Further, since the first member is provided with the corner portion, the member is less likely to rotate and the torsional strength can be improved as compared with the case where the sectional shape is circular. However, if the radius of the R part on the inner peripheral surface of the corner is extremely large, the shape of the outer peripheral surface of the corner is also rounded, and the amount of catching at the corner when twisted is small, which improves the torsional strength. The effect tends to be small. Therefore, R _c /L is defined to be smaller than tan(θ/2)/4 as in the above formula (1), and the angular shape is maintained to secure a certain amount of catching.

Further, when the first member is provided with the corner portion, the deforming force may be concentrated and broken at the corner portion during the expansion deformation. In particular, when the corner portion is a right angle or a rounded corner with a small radius, the deforming force tends to concentrate on the corner portion, and the corner portion may be cracked before being sufficiently expanded and deformed. On the other hand, as in the above formula (1), by defining R _c /L to be larger than tan(θ/2)/((18×n/2)+2), the inner peripheral surface of the corner portion is It has a certain degree of roundness, the rigidity of the corners is reduced, and the corners are easily expanded and deformed. Therefore, it is possible to suppress cracks at the corners and sufficiently expand and deform the first member.

The first member includes an outer wall that defines an outer shape, and an inner rib that partitions an inner space in the outer wall, and an R portion is formed on an inner peripheral surface at an intersection where the outer wall and the inner rib are connected. The corner portion may be provided, and the shape of the corner portion of the intersection may be defined by the following formula.

φ：第１部材の交差部の角部の内周面における角度
ｒ_c：第１部材の交差部の内周面のＲ部の半径
Ｄ_１：第１部材の交差部の角部を構成する２つの辺部のうち一方の辺部の直線長さ
Ｄ_２：第１部材の交差部の角部を構成する２つの辺部のうち一方の辺部の直線長さ
ｎ：第１部材の材料のｎ値（加工硬化指数）
を備えてもよい。

φ: angle r _{c on} the inner peripheral surface of the corner of the intersection of the first member: radius of the R part of the inner peripheral surface of the intersection of the first member D ₁ : configure the corner of the intersection of the first member straight one side portion of the two sides the length D _2: linear length of one side portion of the two sides constituting a corner of the intersection of the first member n: material of first member N value (work hardening index)
May be provided.

According to this method, since the first member includes the inner rib, the rigidity of the first member can be improved. Further, by defining the shape of the corner portion of the intersection where the outer wall and the inner rib of the first member are connected to each other by the equation (2) similarly to the equation (1), cracking at the intersection can be suppressed and the outer wall and The inner rib can be expanded and deformed. Here, ave(D ₁ , D ₂ ) in the equation (2) indicates the average value of D ₁ and D ₂ .

The shape of the hole of the second member and the cross-sectional shape of the portion of the first member that is inserted into the hole may be similar.

According to this method, since the first member and the second member have similar shapes to each other, the first member can be uniformly expanded and deformed and joined, and a local load is applied to the first member and the second member. It can be prevented from occurring. Here, the “similar shape” refers to a case viewed from the axial direction.

When compressing the elastic body, the first member may also be compressed in the axial direction.

According to this method, the first member can also be compressed in the axial direction to assist the outward deformation of the first member. That is, it is possible to more reliably expand and deform the first member in the outer direction in combination with the expanding deformation force from the inside of the first member by the elastic body.

The edge of the hole of the second member may be burred.

According to this method, the strength of the hole of the second member can be improved and the deformation of the second member can be prevented by burring the edge of the hole of the second member. Moreover, since the joining area of the first member and the second member is increased by the burring process, the joining strength can be improved.

A mold may be arranged outside the first member, and at least a part of the first member may be molded and joined along the mold.

According to this method, the first member can be deformed into an arbitrary shape by using molds having various inner surface shapes. The shape to be deformed can be appropriately selected from the viewpoint of component performance and the like and can be a shape according to the application.

An outer frame die may be arranged outside the first member, and the outer frame die may partially limit the expansion deformation of the first member for joining.

According to this method, by using the outer frame mold, it is possible to define the region in which the first member is to be expanded and deformed, and to control the expansion and deformation region with high accuracy. Here, the expansion deformation area refers to an area in which the first member is expanded and deformed outward.

According to the present invention, in the method of processing a member using an elastic body, since the shape of the corner portion of the first member is defined to be easy to process and difficult to crack, cracking is suppressed and the first member is sufficiently expanded. It can be transformed.

The perspective view before joining of the steel part and aluminum pipe which apply the joining method of the member concerning a 1st embodiment of the present invention. The perspective view after joining of the steel part and aluminum pipe which applied the joining method of the member concerning a 1st embodiment of the present invention. Sectional drawing before joining of the joining method of the member which concerns on 1st Embodiment. Sectional drawing before joining of the joining method of the member which concerns on 1st Embodiment. Sectional drawing in the process of joining of the member joining method which concerns on 1st Embodiment. Sectional drawing after joining of the joining method of the member which concerns on 1st Embodiment. Sectional drawing and the elements on larger scale for demonstrating the dimensional relationship of the aluminum pipe of 1st Embodiment. The graph which shows the relationship between the amount of pipe expansion and strain about a side part and a corner part. graph showing the relationship between R _{c /} L and strain ratio when the theta = 90 degrees. graph showing the relationship between _R c / L and strain ratio when the θ = 70,90,110 degrees. Sectional drawing which shows the aluminum pipe of the 1st modification of 1st Embodiment. Sectional drawing before joining of the 2nd modification of 1st Embodiment. Sectional drawing during joining of the 2nd modification of 1st Embodiment. Sectional drawing before joining of the 3rd modification of 1st Embodiment. Sectional drawing after joining of the 3rd modification of 1st Embodiment. Sectional drawing for demonstrating the dimensional relationship of the aluminum pipe of 2nd Embodiment. Sectional drawing before the joining of the joining method of the member which concerns on 2nd Embodiment. Sectional drawing during joining of the joining method of the member which concerns on 2nd Embodiment. The perspective view before joining of the hat-shaped steel component and aluminum pipe which the joining method of the member concerning a 3rd embodiment is applied. The perspective view after joining of the hat-shaped steel component and aluminum pipe to which the joining method of the member concerning a 3rd embodiment was applied. Sectional drawing before the joining of the joining method of the member which concerns on 3rd Embodiment. Sectional drawing during joining of the joining method of the member which concerns on 3rd Embodiment. Sectional drawing during joining of the joining method of the member which concerns on 3rd Embodiment. Sectional drawing after joining of the joining method of the member which concerns on 3rd Embodiment. Sectional drawing before joining of the joining method of the member which concerns on 4th Embodiment. Sectional drawing during joining of the joining method of the member which concerns on 4th Embodiment. Sectional drawing before joining of the joining method of the member which concerns on 5th Embodiment. Sectional drawing during joining of the joining method of the member which concerns on 5th Embodiment. Sectional drawing before joining of the modification of 5th Embodiment. Sectional drawing during joining of the modification of 5th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
With reference to FIGS. 1A to 2D, a method of joining members for joining the aluminum pipe (first member) 20 and the steel component (second member) 10 will be described. In the following, an example in which the steel part 10 and the aluminum pipe 20 are joined is shown as an example of joining dissimilar metals, but the material of the members to be joined is not particularly limited, and as long as the strength is different, steel or It may be made of other than aluminum. Here, the term "strength" refers to general properties related to material deformation and fracture such as yield strength, tensile strength, ductility, rigidity, or bending strength. This also applies to the subsequent second to fifth embodiments.

As shown in FIG. 1A, the steel component 10 is a flat plate made of high tension steel. The steel part 10 is provided with a hole 11 through which the aluminum pipe 20 can be inserted. The aluminum pipe 20 is made of an aluminum alloy and has a hollow tubular shape extending in the direction of the axis L. The axis L passes through the center of the aluminum pipe 20 and the center of the hole 11 of the steel component 10. The detailed shape of the aluminum pipe 20 will be described later.

As shown in FIG. 1B, the aluminum pipe 20 expands radially outward of the axis L, so that the aluminum pipe 20 is pressed against the hole 11 of the steel component 10. The shape and size of the hole 11 of the steel part 10 are preferably similar to the cross-sectional shape of the aluminum pipe 20, and it is more preferable that the hole 11 is as small as possible within the range in which the aluminum pipe 20 can be inserted. Here, the “similar shape” refers to a case viewed from the direction of the axis L.

As shown in FIGS. 2A to 2D, a rubber (elastic body) 30 is used to join the steel component 10 and the aluminum pipe 20.

First, as shown in FIG. 2A, the aluminum pipe 20 is inserted into the hole 11 of the steel component 10, and the rubber 30 is inserted into the aluminum pipe 20 to form the assembly 1 before joining. At this time, the aluminum pipe 20 may be inserted into the hole 11 of the steel part 10 with the rubber 30 inserted therein. Then, as shown in FIG. 2B, the assembly 1 in that state is set in the press device 40.

The pressing device 40 includes an indenter 41 and a seat 42. The indenter 41 includes a columnar convex portion 41a extending downward and a flange portion 41b provided around the convex portion 41a. The lower surface 41c of the convex portion 41a of the indenter 41 is a flat surface. The seat 42 includes a columnar convex portion 42a extending upward and a collar portion 42b provided around the convex portion 42a. The upper surface 42c of the convex portion 42a of the seat 42 is a flat surface, and the rubber 30 is placed on the upper surface 42c of the convex portion 42a of the seat 42.

The rubber 30 has a cylindrical shape with a diameter that can be inserted into the aluminum pipe 20. The length of the rubber 30 may be such that the aluminum pipe 20 can be deformed in the vicinity of the joint. The type of the rubber 30 used is not particularly limited, and for example, urethane rubber, chloroprene rubber, CNR rubber (chloroprene rubber+nitrile rubber), silicon rubber or the like can be used.

Next, as shown in FIG. 2C, the rubber 30 is sandwiched between the lower surface 41c of the convex portion 41a of the indenter 41 and the upper surface 42c of the convex portion 42a of the receiving seat 42 and compressed in the direction of the axis L. The dimension of the rubber 30 in the radial direction increases as the dimension in the axis L direction decreases. In this way, the rubber 30 is elastically deformed so as to expand radially outward from the axis L, and the aluminum pipe 20 is expanded and deformed to be pressed against the steel component 10.

After joining, as shown in FIG. 2D, the rubber 30 from which the compressive force of the pressing device 40 has been removed restores to its original shape by its elastic force. Therefore, the rubber 30 can be easily removed from the aluminum pipe 20.

Here, with reference to FIG. 3, the shape of the aluminum pipe 20 suitable for the above-described member processing method and joining method will be described in detail. The cross-sectional shape of the aluminum pipe 20 is generally trapezoidal in the figure, but may be another polygonal shape. The aluminum pipe 20 is provided with corner portions 23a to 23d having R portions 22a to 22d on the inner peripheral surface 21a. The angle θ of the inner peripheral surface 21a of each of the corner portions 23a to 23d is, for example, in the range of 45 to 135 degrees. Of the corners 23a to 23d, for example, the shape of the R portion 22a of the inner peripheral surface 21a of one corner 23a is defined by the following expression (3). In addition, in this embodiment, the shapes of the other corners 23b to 23d are similarly defined.

θ：アルミパイプの角部の内周面における角度
Ｒ_ｃ：アルミパイプの角部の内周面のＲ部の半径
Ｌ_１：アルミパイプの角部を構成する２つの辺部のうち一方の辺部の直線長さ
Ｌ_２：アルミパイプの角部を構成する２つの辺部のうち他方の辺部の直線長さ
ｎ：アルミパイプの材料のｎ値（加工硬化指数）

θ: Angle Rc on the inner peripheral surface of the corner of the aluminum pipe R _c : Radius L of the R portion on the inner peripheral surface of the corner of the aluminum pipe ₁ : One of the two sides forming the corner of the aluminum pipe Linear length of the part L ₂ : linear length of the other side of the two sides forming the corner of the aluminum pipe n: n value of the material of the aluminum pipe (work hardening index)

Here, ave(L ₁ , L ₂ ) in the above formula (3) indicates the average value of L ₁ and L ₂ , and may be simply referred to as L hereinafter.

In this way, since the aluminum pipe 20 is provided with the corner portion 23a, the members 10 and 20 are less likely to rotate and the torsional strength can be improved, as compared with the case where the cross-sectional shape is circular. However, when the radius R _c of the R portion 22a of the inner peripheral surface 21a of the corner portion 23a is extremely large, the shape of the outer peripheral surface 21b of the corner portion 23a is also rounded, and the amount of catching at the corner portion 23a when twisted. Becomes smaller and the effect of improving the torsional strength tends to be smaller. Therefore, R _c /L is defined to be smaller than tan(θ/2)/4 as in the above expression (3), and the square shape is maintained to secure a certain amount of catching.

Further, when the aluminum pipe 20 is provided with the corner portion 23a, the deformation force may be concentrated and broken at the corner portion 23a during the expansion deformation. In particular, when the corner portion 23a is a right angle or a rounded corner with a small radius, the deformation force is likely to concentrate on the corner portion 23a, and the corner portion 23a may be cracked before being sufficiently expanded and deformed. On the other hand, as in the above formula (3), by defining R _c /L to be larger than tan(θ/2)/((18×n/2)+2), the inner peripheral surface of the corner portion 23a 21a has a certain degree of roundness, the rigidity of the corner portion 23a is reduced, and the corner portion 23a is easily expanded and deformed. Therefore, it is possible to suppress cracking of the corner portion 23a and to sufficiently expand and deform the aluminum pipe 20.

Specifically, the above expression (3) is derived from the following two conditional expressions (4) and (5).

ｃ：アルミパイプの角部を構成する２つの辺部におけるＲ部の直線長さ
ｂ_１：アルミパイプの角部を構成する２つの辺部のうち一方の辺部の直線部の長さ
ｂ_２：アルミパイプの角部を構成する２つの辺部のうち他方の辺部の直線部の長さ

c: Linear length b of the R portion in the two side portions forming the corner of the aluminum pipe b ₁ : Length b ₂ of the straight portion of one of the two side portions forming the corner of the aluminum pipe : Length of the straight part of the other side of the two sides forming the corner of the aluminum pipe

The above expression (4) is a conditional expression for maintaining the angular shape of the corner portion 23a of the aluminum pipe 20. Here, ave(b ₁ , b ₂ ) in the above equation (4) represents the average value of b ₁ and b ₂ , and may be simply referred to as b hereinafter. Specifically, the half length b/2 of the average value b of the lengths b1 and b2 of the straight portions 24a and 24b is made longer than the length c of the corner portion 23a, that is, the corner portion 23a has a predetermined length or more. By providing the linear portion having the length of, the cross-sectional shape is prevented from being substantially circular and the angular shape is maintained.

The above formula (5) is a conditional formula derived by analysis and experiment. Based on the analysis result and the experimental result described later, when the condition of Expression (5) is satisfied, the occurrence of cracks in the aluminum pipe 20 can be suppressed.

The following equation (6) is derived from the above equations (4) and (5).

Further, as shown in FIG. 3, the following two equations (7) are derived from the geometric shape of the corner portion 23a.

The following equation (8) is derived from the above equations (6) and (7), and the above equation (3) is obtained by modifying the equation (8).

Therefore, the shape of the R portion 22a of the inner peripheral surface 21a of the corner portion 23a defined by the above expression (3) is defined by the conditional expression (4) that maintains the angular shape and the conditional expression (5) that can suppress the occurrence of cracks. Meet both.

Here, the above formula (3) will be described in detail based on the results of analysis and experiments. In this embodiment, the material of the aluminum pipe 20 is aluminum, and its n value is 0.2. Further, for example, considering a square cross section (L ₁ and L ₂ may be referred to as L hereinafter) where the angle θ is 90 degrees and L ₁ and L ₂ are equal to each other, the equation (3) is expressed by the following equation (9). , R _c /L range.

FIG. 4A is a graph showing the relationship between the pipe expansion amount and strain obtained by performing analysis on the aluminum pipe 20 under the conditions of angle θ=90 degrees, L ₁ =L ₂ , diameter 80 mm, and radius R _c =10 mm. Is. The upper line (corner strain) in the graph is an analysis result when it is assumed that only the corner 23a is deformed. That is, the corner strain can be expressed as Δc/c, where Δc is the amount of change in the corner length c. The lower line (straight part strain) in the graph is an analysis result when it is assumed that only the straight part 24a is deformed. That is, the linear portion strain can be expressed as Δb/(b/2), where Δb is the change amount of the half length b/2 of the length of the linear portion. As shown in FIG. 4A, the corner strain is larger than the straight part strain, and when the ratio of the corner part strain to the straight part strain (strain ratio) becomes equal to or more than a certain value, cracks occur in the aluminum pipe 20. The strain ratio can be expressed as (Δc/c)/(Δb/(b/2)), which can be approximated to approximately b/2c.

FIG. 4B shows R _c /L when the radius R _c is changed, which is obtained by analyzing the aluminum pipe 20 under the conditions of an angle θ=90 degrees, L ₁ =L ₂ , and a diameter of 80 mm. It is a graph which shows the relationship with the ratio (strain ratio) of the corner|angular strain with respect to the linear part strain of FIG. 4A. The broken line portion in the graph indicates a portion that deviates from the condition of the above expression (9), and the solid line portion indicates a portion that meets the condition of the above expression (9). That is, the solid line portion in the graph is a preferable range for joining.

In order to confirm experimentally that the range within the solid line of the graph of FIG. 4B is effective, the angle θ=90 degrees, L ₁ =L ₂ , the diameter 80 mm, and the thickness 2.0 mm of the aluminum pipe 20, the corner portion The radius R _c of 23a was variously changed and expanded by 10% (=8 mm), and the presence or absence of cracks was verified. The experimental results are shown in Table 1 below.

As shown in Table 1, when R _c /L is 0, 0.0125, or 0.0375, which is a value of 1/20 (=0.05) or less, cracking occurs, and R _c /L is When the value is 0.0625 or 0.125, which is greater than 0.05, no cracks have occurred. Here, when R _c is 0, there is no R portion, and the inner peripheral surface 21a of the corner portion 23a is a right angle. Therefore, it is considered that there is a threshold value for cracking when R _c /L is between 0.0375 and 0.0625, and the threshold value is set to 0.05 in the present embodiment. From the analysis result and the experimental result, it is considered that the crack occurs when the strain ratio becomes 9 or more because the strain ratio is 9 when R _c /L is 0.05. Therefore, as described above, since the strain ratio is represented by b/2c, the case where the strain ratio (b/2c) is less than 9 is preferable for bonding (see the equation (5)). However, in the right side of the above equation (5), the n value of the material is introduced in order to make the material have generality. When R _c /L is ¼ (=0.25) or more, the condition that the angular shape of the corner portion 23a is not maintained is geometrically derived, and thus R _c /L is 0.25. In the above cases, the experiment is not performed (see formula (4)).

FIG. 4C shows a graph obtained by adding the case where the angle θ is 70 and 110 degrees to the graph of FIG. 4B. Similarly to the case where the angle θ is 90 degrees, it is considered that cracks occur when the strain ratio is 9 or more when the angle θ is 70 and 110 degrees, and a similar condition for maintaining the angular shape of the corner portion 23a is obtained. The following two expressions (10) are derived from the conditions. In this way, a preferable range of R _c /L can be derived even when the angle θ is changed, and the shape of the aluminum pipe 20 suitable for joining can be defined.

As shown in FIG. 5, as a first modified example of the present embodiment, the cross-sectional shape of the aluminum pipe 20 does not have to be similar to the cross-sectional shape of the inner peripheral surface 21a and the outer peripheral surface 21b, that is, the cross-sectional shape of the aluminum pipe 20. The plate thickness does not have to be constant. For example, as shown in FIG. 5, it is a substantially square cross section having four corners 23a to 23d, the inner peripheral surface 21a of the corners 23a to 23d is provided with R portions 22a to 22d, and the corners 23a to 23d. The outer peripheral surface 21b may not be provided with the R portion.

As shown in FIGS. 6A and 6B, as a second modified example of the present embodiment, outer frames 41d and 42d may be arranged outside the portion (the end in this modified example) of the aluminum pipe 20 that is not to be expanded and deformed. Good. The outer frames 41d and 42d are cylindrical and arranged around both ends of the aluminum pipe 20. By disposing the outer frames 41d and 42d, it is possible to restrict the deformation of both end portions of the aluminum pipe 20 and to deform only the joint portion, so that the shape can be made according to the intended use.

As shown in FIGS. 7A and 7B, as a third modified example of the present embodiment, burring may be performed on the edge of the hole 11 of the steel component 10. By burring the edge of the hole 11 of the steel part 10, the strength of the hole 11 of the steel part 10 can be improved and deformation of the steel part 10 can be prevented. Further, since the joint area between the steel part 10 and the aluminum pipe 20 is increased by the burring process, the joint strength can be improved.

The processing method of enlarging and deforming the aluminum pipe 20 used in the method of joining members of the present embodiment may be used independently of joining. That is, the aluminum pipe 20 can be expanded and deformed by the rubber 30 to obtain a desired shape regardless of the joining with the steel component 10.

(Second embodiment)
8 to 9B show a method of joining members according to the second embodiment of the present invention. In the present embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the aluminum pipe 20 includes an outer wall 25 that defines an outer shape, and an inner rib 26 that partitions an inner space inside the outer wall 25. The inner rib 26 is formed in a cross shape when viewed from the direction of the axis L, and divides the inner space in the outer wall 25 into four. Therefore, the aluminum pipe 20 includes four inner peripheral surfaces 21c to 21f.

Corners 23e to 23l having R portions 22e to 22l are respectively provided at the four intersections 27a to 27d to which the outer wall 25 and the inner rib 26 are connected. Of the corners 23e to 23l, for example, the shape of the R portion 22e of the inner peripheral surface 21c of one corner 23e is defined by the following equation (11). In addition, in this embodiment, the shapes of the other corners 23f to 23l are similarly defined.

φ：アルミパイプの交差部の角部の内周面における角度
ｒ_ｃ：アルミパイプの交差部のＲ部の半径
Ｄ_１：アルミパイプの交差部の角部を構成する２つの辺部のうち一方の辺部の直線長さ
Ｄ_２：アルミパイプの交差部の角部を構成する２つの辺部のうち他方の辺部の直線長さ
ｎ：アルミパイプの材料のｎ値（加工硬化指数）

phi: angle of the inner peripheral surface of the corner of the intersection of the aluminum pipe r _c: radius D ₁ of the R portion of the intersection of the aluminum _pipe: one of the two sides constituting a corner of the intersection of the aluminum pipe Linear length of the side part D ₂ : linear length of the other side of the two side parts forming the corner of the intersection of the aluminum pipe n: n value of the material of the aluminum pipe (work hardening index)

Here, ave(D ₁ , D ₂ ) of the equation (11) indicates the average value of D ₁ and D ₂ . The above formula (11) corresponds to the formula (3) of the first embodiment. Therefore, the derivation and the meaning of the equation (11) are the same as those of the equation (3) in the first embodiment.

In the present embodiment, the inner space inside the outer wall 25 of the aluminum pipe 20 is divided into four by the inner ribs 26, so four rubbers 30 to be inserted into the aluminum pipe 20 are required. That is, one rubber 30 is inserted into each internal space partitioned by the inner rib 26.

The protrusion 41a of the indenter 41 of the present embodiment is provided with a groove 41e corresponding to the inner rib 26. Therefore, even if the convex portion 41a of the indenter 41 is inserted into the aluminum pipe 20, the rubber 30 can be pressed without interfering with the inner rib 26.

According to this embodiment, since the aluminum pipe 20 includes the inner rib 26, the rigidity of the aluminum pipe 20 can be improved. Further, by defining the shapes of the corners 23e to 23l of the intersections 27a to 27d of the aluminum pipe 20 as shown in Expression (10), cracking of the intersections 27a to 27d can be suppressed and the outer wall 25 and the inner rib 26 can be prevented. Can be expanded and transformed.

(Third Embodiment)
10A to 11D show a method for joining members according to the third embodiment of the present invention. In the present embodiment, the same components as those in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 10A, the steel part 10 has a channel type shape made of high tension steel. The steel component 10 includes a bottom wall 12, two sidewalls 13 extending vertically upward from the bottom wall 12, and an upper wall 14 extending horizontally outward from each of the two sidewalls 13. The bottom wall 12 is provided with a hole 11 through which the aluminum pipe 20 can be inserted.

As shown in FIG. 10B, the aluminum pipe 20 is expanded and deformed outward in the radial direction, and the upper end of the aluminum pipe 20 is crushed to be joined to the hole 11 of the steel component 10. In this way, both members 10 and 20 may be joined not only by simply expanding the aluminum pipe 20 but also by crushing the ends.

The joining method will be described in detail. As shown in FIG. 11A, the aluminum pipe 20 is inserted into the hole 11 of the steel component 10, the rubber 30 is inserted into the aluminum pipe 20, and the aluminum pipe 20 is set in the press device 40. .. However, the aluminum pipe 20 may be inserted into the hole 11 with the rubber 30 inserted therein. The pressing device 40 includes an indenter 41 and a seat 42. The indenter 41 has a flat lower surface 41c. The receiving seat 42 has a flat upper surface 42c, and the steel part 10 and the rubber 30 are placed on the upper surface 42c. The rubber 30 has a cylindrical shape having a diameter that can be inserted into the aluminum pipe 20, and has a length longer than that of the aluminum pipe 20. Therefore, in the set state, the rubber 30 partially projects from the upper end of the aluminum pipe 20. Therefore, when the pressing device 40 starts pressing and the receiving seat 42 and the indenter 41 relatively approach each other, the rubber 30 is first pressed. However, the rubber 30 does not necessarily have to protrude from the upper end of the aluminum pipe 20, and may be housed flush with or inside the upper end of the aluminum pipe 20.

Next, as shown in FIG. 11B, the rubber 30 is compressed in the axis L direction by the pressing device 40. The dimension of the rubber 30 in the radial direction increases as the dimension in the direction of the axis L decreases. In this way, the rubber 30 is expanded outward from the axis L, and the aluminum pipe 20 is expanded and deformed. Then, as shown in FIG. 11C, the aluminum pipe 20 is further expanded and deformed by being further compressed by the pressing device 40, and at the same time, the upper end of the aluminum pipe 20 in the drawing is bent and pressed toward the steel part 10. Crush and join with the steel part 10.

After joining, as shown in FIG. 11D, the rubber 30 from which the compression force of the pressing device 40 has been removed restores to its original shape by its own elastic force. Therefore, the rubber 30 can be easily removed from the aluminum pipe 20.

As in the present embodiment, the shape of the steel part 10 may be a hat shape or another shape, and is not particularly limited. Further, the mode of joining including the aspect of the pressing device 40 is not particularly limited, and can be variously performed such as pipe joining and joining in which the end portion is crushed.

(Fourth Embodiment)
12A and 12B show a method for joining members according to the fourth embodiment of the present invention. In the present embodiment, the same components as those in the first to third embodiments are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 12A, in this embodiment, the steel part 10 and the aluminum pipe 20 are joined using the form 43. The mold 43 has a cylindrical shape that is concentric with the aluminum pipe 20. The mold 43 is arranged between the receiving seat 42 and the steel component 10 and outside the aluminum pipe 20. A gap is provided between the aluminum pipe 20 and the mold 43 when set in the pressing device 40. In this state, as shown in FIG. 12B, by pressing with the indenter 41, it is possible to conform to the inner surface shape of the mold 43 when the aluminum pipe 20 is expanded and deformed.

According to this method, the inner surface of the mold 43 can have various polygonal shapes. The shape may be appropriately selected from the viewpoint of component performance. For example, in the case where the aluminum pipe 20 is a bumper stay which is one of automobile parts, if minute irregularities are provided on the inner surface of the mold 43, the minute irregularities are transferred to the aluminum pipe 20 and a collision occurs. It is possible to improve the collision energy absorption performance.

(Fifth Embodiment)
13A and 13B show a method for joining members according to the fifth embodiment of the present invention. In the present embodiment, the same components as those in the first to fourth embodiments are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 13A and 13B, in the present embodiment, a cylindrical outer frame die 44 that partially restricts the expansion deformation is arranged around the aluminum pipe 20. The outer frame die 44 has an enlarged diameter portion 44a having a large inner diameter in the vicinity of the joint so that it is expanded and deformed only in the vicinity of the joint. The inner diameter of the aluminum pipe 20 other than the enlarged diameter portion 44a is substantially equal to the outer diameter of the aluminum pipe 20.

When the outer frame die 44 is used, the expansion deformation region can be controlled with high accuracy so that only the vicinity of the joined portion of the aluminum pipe 20 is expanded and deformed. Here, the expansion deformation area means an area in which the aluminum pipe 20 is expanded and deformed outward.

As shown in FIG. 14A, the indenter 41 included in the pressing device 40 may have a truncated cone shape that is tapered downward in the drawing. A high forming force may be required for the enlarged deformation of the end portion of the aluminum pipe 20 protruding upward in the drawing of the steel part 10. In such a case, the shape of the indenter 41 that can directly deform the aluminum pipe 20 by the indenter 41 is effective.

As shown in FIG. 14B, at the final stage of molding, the upper end of the aluminum pipe 20 projecting to the upper side of the steel part 10 in the drawing is directly expanded outward by the indenter 41 without the rubber 30, and It is bent towards the steel part 10. As a result, it is possible to bond more firmly. Further, since the rubber 30 is not subjected to an excessive load, the durability of the rubber 30 is improved.

Although specific embodiments of the present invention and modifications thereof have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be carried out within the scope of the present invention. For example, an appropriate combination of the contents of the individual embodiments may be an embodiment of the present invention.

1 Assembly 10 Steel part (second member)
11 Holes 12 Bottom Wall 13 Side Wall 14 Top Wall
20 Aluminum pipe (first member)
21a, 21c to 21f Inner peripheral surface 21b Outer peripheral surface 22a to 22l R portion 23a to 23l Corner portion 24a to 24d Straight portion 25 Outer wall 26 Inner rib 27a to 27d Crossing portion 30 Rubber (elastic body)
40 Pressing device 41 Indenter 41a Convex part 41b Collar part 41c Lower surface 41d Outer frame 41e Groove part 42 Seat 42a Convex part 42b Collar part 42c Upper surface 42d Outer frame 43 Form frame 44 Outer frame mold 44a Expanding part

Claims (8)

A first member having a hollow shape that extends in the axial direction, a corner portion having an R portion is provided on the inner peripheral surface of the cross-sectional shape in the axial direction, and the shape of the corner portion is defined by the following formula: Prepare an elastic body and
Inserting the elastic body inside the first member,
A method for processing a member, comprising compressing the elastic body in the axial direction to expand the elastic body outward in the radial direction of the axial line, thereby expanding and deforming the first member.

theta: angle R _c of the inner peripheral surface of the corner portion of the first _member: radius L ₁ of the R portion of the inner peripheral surface of the corner portion of the first _member: one of the two sides constituting a corner of the first member Linear length L _{2 of} one side: linear length n of the other side of the two sides forming the corner of the first member n: n value of the material of the first member (work hardening index) Further preparing a second member having a hole different in strength from the first member,
Inserting the first member through the hole of the second member,
A method for joining members, comprising: enlarging and deforming the first member to join the first member and the second member using the method for working a member according to claim 1. The first member includes an outer wall that defines an outer shape, and an inner rib that partitions an inner space inside the outer wall,
A corner portion having an R portion on the inner peripheral surface is provided at the intersection where the outer wall and the inner rib are connected, and the shape of the corner portion of the intersection is defined by the following formula: Item 3. A method for joining members according to item 2.

phi: angle r _c of the inner peripheral surface of the corner of the intersection of the first _member: radius D ₁ of the R portion of the inner peripheral surface of the intersection of the first _member: constituting a corner of the intersection of the first member straight one side portion of the two sides the length D _2: linear length of one side portion of the two sides constituting a corner of the intersection of the first member n: material of first member N value (work hardening index) The member joining method according to claim 2, wherein the shape of the hole of the second member and the cross-sectional shape of a portion of the first member that is inserted into the hole are similar shapes. The method for joining members according to any one of claims 2 to 4, wherein when the elastic body is compressed, the first member is also compressed in the axial direction. The member joining method according to claim 2, wherein an edge of the hole of the second member is burred. The mold is arranged outside the first member, and at least a part of the first member is molded and joined along the mold, and the mold is bonded to the mold. Method of joining members. The outer frame mold is arranged outside the first member, and the expansion deformation of the first member is partially limited by the outer frame mold to join the first frame and the second frame. The method for joining members according to.

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