JP2009154563A - Vehicle body frame member and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make cross-sectional peripheral length, plate thickness and a raw material different depending on longitudinal positions, while restraining cost increase, in a tubular vehicle body frame member and its manufacturing method using hydroforming molding. <P>SOLUTION: A rear frame 3 is manufactured by applying the hydroforming molding by including a double tube structure part 3a in a work W, by forming the work W having partially the double tube structure 3a by inserting the other steel pipe 11 into one steel pipe 12, by using the steel pipes 11 and 12 of the different size being substantially the same in one outer peripheral shape and the other inner peripheral shape. The rear frame 3 has the double tube structure part 3a high in relative strength rigidity and a single tube structure part 3b low in relative strength rigidity at different longitudinal parts, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a body frame member and a manufacturing method thereof.

Conventionally, in a vehicle body such as a general passenger car, a monocoque structure in which panel parts and frame parts are integrally joined by welding or the like is often used to reduce the weight and increase the rigidity. Among such frame members of the vehicle body, a tubular member having a relatively complicated shape is formed by filling a liquid in an existing hydroform molding (a metal tube set in a mold, pressurizing the liquid, and Manufacturing may be performed by a method in which a metal tube is bulged to a shape that follows the internal shape of the mold (see, for example, Patent Documents 1 to 3).
Japanese Patent No. 3724621 Japanese Patent No. 3833880 US Pat. No. 5,333,775

By the way, when manufacturing the tubular body frame member by the conventional general hydroforming, it is possible to form different cross-sectional shapes relatively freely depending on the position in the longitudinal direction. When manufacturing the vehicle body frame member as described above, the frame frame design is limited because almost the same (constant) cross-sectional circumference and plate thickness are used at any position in the longitudinal direction, and the material is the same over the entire length. There is a problem that arises.
In addition, as a method to compensate for the above points, a tailored tube (a pipe made of a steel plate having a different thickness or material depending on the part) or a tapered tube (a pipe whose cross-sectional circumference is changed depending on the position in the longitudinal direction) is used as a material. However, in this case, there is a problem of significantly increasing the material cost and thus the frame manufacturing cost.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tubular body frame member using hydroform molding and a method for manufacturing the tubular body frame member so that the cross-sectional peripheral length, the plate thickness, and the material are varied depending on the longitudinal position while suppressing an increase in cost.

  As a means for solving the above-mentioned problems, the invention described in claim 1 uses metal pipes of different sizes (for example, steel pipes 11 and 12 in the embodiments) in which one outer peripheral shape and the other inner peripheral shape are substantially the same. The other metal tube is inserted into the one metal tube to form a workpiece (for example, the workpiece W of the embodiment) partially having a double tube structure portion (for example, the double tube structure portion 3a of the embodiment), A method of manufacturing a vehicle body frame member, wherein the work is subjected to hydroforming including the double pipe structure portion.

  The invention described in claim 2 is characterized in that after forming a work having the double pipe structure and partially expanding the double pipe structure, the work is hydroformed. The manufacturing method of a vehicle body frame member according to Item 1.

  According to a third aspect of the present invention, in a tubular body frame member (for example, the rear frame 3 of the embodiment) having a different cross-sectional shape depending on the position in the longitudinal direction by hydroforming, a relatively strong rigidity is provided at a portion different in the longitudinal direction. Each having a high double tube structure (for example, the double tube structure 3a of the embodiment) and a single tube structure (for example, the single tube structure 3b of the embodiment) having relatively low strength and rigidity. The vehicle body frame member is characterized in that the hydroform molding is performed including a heavy pipe structure.

  The invention described in claim 4 is the vehicle body frame member according to claim 3, wherein the double pipe structure portion is provided in a curved shape and the single pipe structure portion is provided in a straight shape.

  According to the invention described in claims 1 and 2, a plurality of metal tubes having similar cross-sectional shapes of slightly different sizes are used to form a workpiece partially having a double pipe structure, and the workpiece is By performing hydroform molding including the double-pipe structure part, the cross-sectional circumference, plate thickness and material are elongated using relatively inexpensive materials without using expensive special materials such as tailored tubes and tapered tubes. It becomes possible to manufacture a vehicle body frame member that varies depending on the direction position. As a result, it is possible to easily set a difference in strength and rigidity between different parts of the body frame member in the longitudinal direction, and it is possible to increase the degree of freedom in frame design while suppressing an increase in cost.

  According to the third and fourth aspects of the invention, in the vehicle body frame member subjected to hydroforming, it is possible to vary the cross-sectional circumferential length, the plate thickness, and the material depending on the position in the longitudinal direction using a relatively inexpensive material. Accordingly, it is possible to easily set a difference in strength and rigidity between portions of the vehicle body frame member having different longitudinal directions, and it is possible to increase the degree of freedom in frame design while suppressing an increase in cost.

  Hereinafter, an example in which the present invention is applied to a rear frame of a vehicle body of a passenger car will be described with reference to the drawings. Note that the directions such as front, rear, left and right in the following description are the same as those in the vehicle unless otherwise specified. In the figure, the arrow FR indicates the front of the vehicle, the arrow LH indicates the left side of the vehicle, and the arrow UP indicates the upper side of the vehicle.

  FIG. 1 shows a rear portion of a vehicle body 1 having a monocoque structure in which panel parts and frame parts in a general passenger car are integrally joined by welding or the like. Left and right side sills 2 extending in the front-rear direction are respectively disposed on the left and right sides of the floor portion of the vehicle body 1. The left and right inner sides of the rear end portions of the left and right side sills 2 are joined to the front end portions of the left and right rear frames 3 extending rearward after being displaced from the rear end portion to the left and right inner sides, respectively. A middle cross member 4 is provided between the rear end portions of the left and right side sills 2, and a rear cross member 5 is provided between the front and rear intermediate portions of the left and right rear frames 3. A rear bumper beam 6 is attached to the rear ends of the left and right rear frames 3. In the left and right side sill 2, only the side sill inner 2a constituting the left and right inner sides is indicated by a solid line. In addition, a line CS in the figure indicates the left and right center plane of the vehicle body.

  Referring also to FIG. 2, the left and right rear frames 3 are tubular ones having a hollow square cross-sectional shape (extending with a closed cross-sectional structure), and the front portion thereof is an inner / outer frame member 7. , 8 and a single-pipe structure portion 3b in which only the inner frame member 7 extends rearward (see FIG. 3 (e)). The double-pipe structure part 3a has a relatively high strength and rigidity because it has a longer cross-sectional outer peripheral length and a larger plate thickness than the single-pipe structure part 3b, and is composed of a plurality of members.

  The double-pipe structure portion 3a (the front portion of the inner frame member 7 and the outer frame member 8) is gently curved so that the front end side faces the left and right outer sides, and the front end side is gentle so that the cross-sectional shape is enlarged. It is provided in a tapered shape. The front end of the double pipe structure 3a (the front end of the rear frame 3, the front ends of the inner and outer frame members 7 and 8) is cut along the left and right inner surfaces substantially orthogonal to the left and right directions at the rear end of the side sill inner 2a. Is joined to the inner surface of the rear end of the side sill inner 2a. A flange f1 for welding with the side sill inner 2a is formed at the front end of the rear frame 3, so that not only arc welding but also spot welding is possible. Further, flanges f2 and f3 for welding with the side sill inner 2a and the rear frame 3 are formed at both ends of each of the cross members 4 and 5, thereby enabling both arc welding and spot welding.

On the other hand, the single-pipe structure portion 3b (the rear portion of the inner frame member 7) has a substantially constant cross-sectional shape and is a straight line extending along the front-rear direction, and its rear end is along a surface substantially orthogonal to the front-rear direction. Cut. A flange f4 for connection with a rear panel (not shown) is formed at the rear end (rear end of the rear frame 3) of the single pipe structure portion 3b, but another part is joined instead of the flange f4. Also good.
A straight chamfered shape c1 is formed at a corner of the square cross-sectional shape in the single tube structure 3b, and a chamfered shape c1 is formed at a corner of the square cross-sectional shape at the rear of the double tube structure 3a. The continuous chamfered shape c2 is formed so as to gradually change and terminate in the middle.

The front portion of the inner frame member 7 is inserted into the outer frame member 8 and formed so that the outer peripheral surface of the inner frame member 7 is aligned with the inner peripheral surface of the outer frame member 8. 8 are joined together. The rear end of the outer frame member 8 is cut along a plane that is substantially orthogonal to the front-rear direction, but it does not matter whether the rear end is joined to the outer peripheral surface of the inner frame member 7 or not.
A bracket b1 for attaching the rear suspension member is joined to the lower side of the front part of the rear frame 3, and a connecting member b2 to the rear hoe house is connected to the rear frame 3 at the upper part of the front and rear middle part and the left and right sides. It is joined so as to straddle front and back.

Here, the vehicle body structural parts excluding the outer frame member 8 and the cross members 4 and 5 shown in FIGS. 1 and 2 are made of a general structural steel pipe such as STKM11A of JIS G 3445, for example, and the outer frame member 8 and each cross member. 4 and 5 are made of a high-tensile steel pipe such as STKM14B of JIS G 3445, for example.
This is because the strength and rigidity of the rear portion of the rear frame 3 (the portion that is not reinforced by the outer frame member 8 and the cross members 4 and 5) is relatively lowered, so that the rear portion of the rear frame 3 during a rearward collision of the vehicle (rear collision). The rear portion of the rear frame 3 (the portion reinforced by the outer frame member 8 and each of the cross members 4 and 5) is relatively increased in strength and rigidity. The rear suspension is supported around the front part of the rear frame 3 to prevent the deformation at the time of the collision from reaching the passenger compartment space. This is to increase it.

Next, a method for manufacturing the rear frame 3 will be described with reference to FIG.
First, the linear round steel pipes 11 and 12 used as the inner and outer frame members 7 and 8 are prepared (see FIG. 3A). Hereinafter, the first steel pipe 11 corresponds to the inner frame member 7 and the second steel pipe 12 corresponds to the outer frame member 8.
The first steel pipe 11 is longer than the second steel pipe 12, and the outer diameter of the first steel pipe 11 and the inner diameter of the second steel pipe 12 are substantially the same. That is, the outer diameter of the first steel pipe 11 is obtained by subtracting the outer diameter of the second steel pipe 12 by the thickness of the second steel pipe 12. Moreover, the material and plate thickness of each steel pipe 11 and 12 are mutually different. Specifically, the material of the first steel pipe 11 is, for example, the STKM 11A and the plate thickness is relatively thin, while the material of the second steel pipe 12 is, for example, the STKM 14B, and the plate thickness is relatively thick.

Next, after inserting one side of the first steel pipe 11 into the second steel pipe 12 and fixing the relative positions thereof by caulking or the like to form an integrated work W (see FIG. 3B), A portion where the steel pipes 11 and 12 are overlapped (corresponding to the double pipe structure 3a) is expanded by a tube expansion process or the like to form a tapered end spread shape (see FIG. 3C).
Next, after bending a necessary part of the work W by pipe bender processing or the like (see FIG. 3D), the work W is set in a hydroform mold (after being crushed as necessary). Hydroform molding is performed to form a desired three-dimensional shape (see FIG. 3E). As a result, the steel frames 11, 12 are in close contact with each other and firmly integrated, and the rear frame 3 in which one side in the longitudinal direction is a double pipe structure 3a and the other side is a single pipe structure 3b. Is configured.

The rear frame 3 manufactured in this way has a different cross-sectional shape depending on the position in the longitudinal direction, and has a different cross-sectional size (cross-sectional circumferential length), plate thickness and material on one side and the other side in the longitudinal direction. It can be said that.
That is, the double-pipe structure part 3a constituting one side in the longitudinal direction of the rear frame 3 has a larger cross-sectional size (cross-sectional circumferential length) than the single-pipe structure part 3b constituting the other side in the longitudinal direction of the rear frame 3. Is long), the plate thickness is also thick, and since the material has a high-strength steel layer on the outer periphery, the strength and rigidity are relatively high. In addition, the double-pipe structure 3a, which is the support side of the rear frame 3 (the side coupled to the side sill 2), is expanded so that the cross-sectional shape is enlarged toward the front end side (side sill 2 side). The strength rigidity against the load and the rear wheel support rigidity can be increased.

On the other hand, the single-pipe structure portion 3b has a smaller cross-sectional size (shorter cross-sectional peripheral length) and a smaller plate thickness than the double-pipe structure portion 3a, and is made of a single layer of general structural steel. Therefore, the strength and rigidity are relatively low, and the ease of deformation at the time of vehicle rear-end collision is ensured to improve shock absorption.
The hydroform molding described above is a method in which the steel pipes 11 and 12 set in a mold are filled with a liquid, and the liquid is pressurized to bulge the steel pipes 11 and 12 to follow the internal shape of the mold. It is an existing method of forming a shape.

  As described above, the method of manufacturing the vehicle body frame member (rear frame 3) in the above embodiment uses the steel pipes 11 and 12 having different sizes in which one outer peripheral shape and the other inner peripheral shape are substantially the same. After the other steel pipe 11 is inserted into the one steel pipe 12 to form a work W partially having a double pipe structure 3a, and the double pipe structure 3a is partially expanded, the work W In addition, the double tube structure 3a is included to perform hydroform molding.

  According to this configuration, the workpiece W having the double-pipe structure portion 3a is partially formed by using the plurality of steel pipes 11 and 12 having a similar cross-sectional shape having a slightly different size, and the workpiece W By performing hydroform molding including the pipe structure 3a, the cross-sectional circumference, plate thickness and material can be adjusted in the longitudinal direction using relatively inexpensive materials without using expensive special materials such as tailored tubes and tapered tubes. It is possible to manufacture the rear frame 3 that varies depending on the position. As a result, it is possible to easily set a difference in strength and rigidity between different parts in the longitudinal direction of the rear frame 3, and it is possible to increase the degree of freedom in frame design while suppressing an increase in cost.

  In addition, the body frame member (rear frame 3) in the above embodiment is a tubular member having a cross-sectional shape that differs depending on the position in the longitudinal direction by hydroforming, and has a curved shape with relatively high strength and rigidity at different portions in the longitudinal direction. Each has a double-pipe structure part 3a and a linear single-pipe structure part 3b with relatively low strength and rigidity, and the hydroform molding is performed including the double-pipe structure part 3a.

  According to this configuration, in the rear frame 3 subjected to hydroforming, it becomes possible to vary the cross-sectional circumferential length, the plate thickness, and the material depending on the position in the longitudinal direction using a relatively inexpensive material. Similarly, it is possible to easily set a difference in strength and rigidity between different parts in the longitudinal direction of the rear frame 3, and it is possible to increase the degree of freedom in frame design while suppressing an increase in cost.

In addition, this invention is not restricted to the said Example, For example, the raw material of the rear frame 3 may be not only a round steel pipe but the metal pipe which has cross-sectional shapes, such as a square. That is, it is only necessary to use metal tubes of different sizes in which one outer peripheral shape and the other inner peripheral shape are substantially the same. The material is not limited to a steel pipe, and an aluminum pipe, a stainless steel pipe, or the like may be used as appropriate. Furthermore, the cross-sectional peripheral length, plate thickness, material, and the like of each metal tube may be the same as appropriate.
Moreover, the position, the number, etc. of the single pipe structure part 3b and the double pipe structure part 3a can be changed as appropriate, and the position, the number, etc. of the expanded pipe part can also be changed as appropriate. Further, the single-pipe structure portion 3b may use a high strength material such as a high-tensile material in addition to the general structural steel pipe.
The configuration in the above embodiment is an example of the present invention, and is not limited to the application to the rear frame 3 of a passenger car, and vehicles other than passenger cars (buses, trucks, motorcycles and tricycles, motorbikes, bicycles, four wheels Needless to say, various modifications can be made without departing from the gist of the invention.

It is a top view of the main components of the vehicle body rear part in the Example of this invention. It is a disassembled perspective view of the main components of the said vehicle body rear part. It is explanatory drawing which shows the manufacturing process in order of the rear frame of the said vehicle body from the side, (a)-(e).

Explanation of symbols

1 Body 3 Rear frame (body frame member)
3a Double pipe structure 3b Single pipe structure 11, 12 Steel pipe (metal pipe)
W Work

Claims (4)

  Using a metal tube of a different size whose one outer peripheral shape and the other inner peripheral shape are substantially the same, the other metal tube is inserted into the one metal tube and partially has a double tube structure part And a hydroform molding is performed on the workpiece including the double pipe structure portion.   2. The vehicle body frame member according to claim 1, wherein a workpiece having the double-pipe structure part is formed, and the double-pipe structure part is partially expanded, and thereafter, the work is hydroformed. 3. Production method.   In a tubular body frame member having a cross-sectional shape that varies depending on the position in the longitudinal direction by hydroforming, a double-pipe structure portion having a relatively high strength and rigidity and a single tube structure having a relatively low strength and rigidity are provided at different portions in the longitudinal direction. The vehicle body frame member is characterized in that the hydroform molding is performed including the double pipe structure portion. The vehicle body frame member according to claim 3, wherein the double pipe structure portion is provided in a curved shape, and the single pipe structure portion is provided in a straight shape.

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