JP2000103359A - Cross member for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten the weight, to improve the rigidity, to reduce the manufacturing cost, and to facilitate coping with the car model change by setting the wall-thickness of a major part of a hollow part whose bore in a connecting part to a side frame is larger than the adjacent to the central part, to a specified numerical value or less. SOLUTION: A cross member 11 formed by casting a spherical graphite cast iron material is so constituted that a connecting part 13 to a side frame is larger than the adjacent part of the central part 14 and the wall-thickness of the major part of a hollow part 12 is substantially set to 10 mm or less. The cross member 11 is formed by casting aluminium alloy in a casting mold which is formed of only main molds and a simple-shape core, and has a cavity of a thin-wall and approximately drum-shaped cross member, and treated by heat. The cross member 11 constituted in this way can be lightened approximately 15% than those made of the conventional steel plate and improve the rigidity approximately 10%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross member for an automobile (hereinafter simply referred to as "cross member") extending in a vehicle width direction and connected to left and right side frames, and more particularly to a cross member formed by casting. .

[0002]

2. Description of the Related Art Cross members are important parts which are connected to left and right side frames to ensure rigidity of a vehicle body. In the case of a truck, as shown in FIG.
Are used at each of the front and rear ends of the side frame 42 and between 4 and 8 between them, for a total of 6 to 10 pieces.

Conventionally, a cross member is formed by press-forming a steel plate, and holes and screw holes are formed in the cross member and attached members are attached. 7A and 7B show an example of a conventional steel sheet cross member used for a truck, wherein FIG. 7A is a plan view and FIG. 7B is a front view. 7 has a width (W4) of 820 mm and a depth (F4) of 320.
mm, height (H4) 80mm, thickness (T4) 6mm,
It is made of (JIS) SAPH540 steel plate and has been manufactured mainly by press forming in several steps. In the case of the cross member shown in FIG. 7, the mass is 33 kg.

[0004]

The mass of the vehicle body must be reduced as much as possible in order to improve the fuel efficiency of the automobile and to increase the loading mass of the truck. The steel plate cross member has a large mass and room for weight reduction. When the load weight is increased, it is necessary to further improve the rigidity. In addition, since the press dies for forming the steel sheet cross members are also large, one type of vehicle is required for each type of vehicle.
Difficult to change according to the individual. Further, since the steel sheet cross member is press-formed in several steps, and an attached member is separately manufactured and attached, the manufacturing cost is likely to increase.

[0005] It is conceivable to improve the rigidity of a steel sheet cross member by using a cast member as a cross member to make it easy to respond to changes in vehicle types. However, simply using a cast member increases the mass and cannot reduce the manufacturing cost. Sometimes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cross member which can reduce the weight and increase the rigidity, reduce the manufacturing cost, and can easily cope with a change in vehicle type.

[0007]

Means for Solving the Problems The inventors of the present invention have formed a thin and substantially drum-shaped cross member cavity using only a main mold and a core of a simple shape as molds, and formed spheroidal graphite cast iron or By casting with an aluminum alloy, it was possible to reduce the weight and improve the rigidity, to reduce the manufacturing cost, and to obtain a cross member which can easily respond to changes in vehicle types.

That is, the cross member of the present invention is a cross member for an automobile which extends in the vehicle width direction and is connected to left and right side frames, wherein the diameter of the connection portion with the side frame is larger than that near the center. The thickness of the main part of the hollow part is substantially 10 mm or less, and the hollow part is formed of a casting.

The cross member of the present invention is characterized in that the diameter of the connecting portion is square and / or circular, and preferably has a wall at the center.

Further, the cross member of the present invention is made of a spheroidal graphite cast iron material or an aluminum alloy. (JIS) AC4CH for aluminum alloy
It is preferred that

[0011]

Embodiments of the present invention will be described below. First Embodiment FIG. 1 is a perspective view showing a cross member 11 according to a first embodiment. The cross member 11 has a width (W1) of 820 mm,
The depth (F1) is 320 mm, the hollow portion 12 has a rectangular shape, and the connection portion 13 with the side frame (not shown) is larger than the vicinity of the central portion 14. The thickness of the main portion (T1)
Is 8 mm. And (JIS) FCD400
It is cast with spheroidal graphite cast iron material. This cross member 1
1 has a mass of 28 kg. The cross member 11 is 1 to the mass of 33 kg of the conventional steel plate cross member 41.
5% weight reduction. Furthermore, the rigidity of the cross member 11
Can be improved by 10% compared to the conventional steel plate cross member.

FIG. 5 is a sectional view of a main part of a mold 51 for casting the cross member 31. A cavity 55 is formed by the main mold 52, the main mold 53, and the core 54 having a simple shape, and a spheroidal graphite cast iron having a composition of (JIS) FCD400 is injected into the cavity 55 to cast the cross member 31. Since the mold 51 forms the cavity 55 of the thin and substantially drum-shaped cross member 53 using only the main molds 51 and 52 and the core 54 having a simple shape, the manufacturing cost can be reduced and it is easy to cope with a change in vehicle type.

Second Embodiment FIG. 2 is a perspective view showing a cross member 21 according to a second embodiment. The cross member 21 has a width (W2) of 820 mm,
It has a depth (F2) of 320 mm, a circular hollow portion 22, and a connecting portion 23 to a side frame (not shown) is larger than the vicinity of the central portion 24, and the thickness of the main portion (T2)
Is 8 mm. Then, it is cast with an aluminum alloy of (JIS) AC4CH, and is subjected to a T6 heat treatment after the casting. The mass of the cross member 21 is 22 kg. The cross member 21 can be reduced in weight by 30% with respect to the mass of 33 kg of the conventional steel plate cross member 41. Further, the rigidity of the cross member 21 can be improved by 25% compared to the conventional steel plate cross member 41.

Third Embodiment FIG. 3 is a perspective view showing a cross member 31 according to a third embodiment. The cross member 31 has a width (W3) of 820 mm,
It has a depth (F3) of 320 mm, has a hollow portion 22 in which a square and a circle are combined, forms a wall 35 in a central portion 34, and integrates a bracket 36 with a main portion having a thickness of 8 mm.
mm. Then, it is cast with an aluminum alloy of (JIS) AC4CH, and is subjected to a T6 heat treatment after the casting. The mass of the cross member 31 is 24 g. The cross member 21 can be reduced in weight by 27% with respect to the mass 33 kg of the conventional steel plate cross member 41. Further, the rigidity of the cross member 21 is the same as that of the conventional steel plate cross member 41.
And the rigidity can be further improved by the wall 35.

FIG. 6 is a sectional view of a main part of a mold 61 for casting the cross member 31. The main dies 62a and 62b, the main dies 63a and 63b, and the simple shape inserts 64a and 64b
To form a cavity 65, and (JIS) AC4C
The cross member 31 is cast by injecting a molten aluminum alloy having an H composition. The mold 61 includes main dies 62a and 62b, main dies 63a and 63b, and simple shape nests 64a and 64b.
, The cavity 55 of the thin and substantially drum-shaped cross member 53 is formed. Further, in the conventional steel plate cross member 41, the separately manufactured accessory member is integrally cast as the bracket 37, so that the manufacturing cost is reduced. It is possible and it is easy to respond to a change in vehicle type.

[0016]

As described above, the cross member of the present invention forms a mold having a thin and substantially drum-shaped cross member cavity only with the main mold and the simple core, and this mold is made of aluminum alloy. , And subjected to T6 heat treatment, so that the weight can be reduced and the rigidity can be improved, the manufacturing cost can be reduced, and it is easy to cope with a change in vehicle type.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cross member having a rectangular hollow portion according to the first embodiment.

FIG. 2 is a perspective view of a cross member having a circular hollow portion according to a second embodiment.

FIG. 3 is a perspective view of a cross member according to a third embodiment in which a hollow portion is a combination of a square and a circle and a bracket is integrated.

FIG. 4 is a side view of a truck to which a cross member can be attached.

FIG. 5 is a sectional view of a main part of a mold for casting the cross member according to the first embodiment.

FIG. 6 is a sectional view of an essential part of a mold for casting a cross member according to a third embodiment.

7 (a) is a plan view and FIG. 7 (b) is a front view of a conventional steel sheet cross member.

[Explanation of symbols]

11, 21, 31: Cross member, 41: Steel plate cross member, 12, 22, 32: Hollow portion, 13, 23, 3
3: Connecting part, 14, 24, 34: Central part, 16, 26,
36: mounting hole to frame, 35: wall, 37: bracket, 40: truck, 42: side frame, 5
1: Mold, 52, 53, 62a, 62b, 63a, 63
b: main type, 54: core, 64a, 64b: nest, 55,
65: cavity.

Claims (8)

[Claims] 1. A cross member for an automobile, which extends in a vehicle width direction and is connected to left and right side frames, and has a hollow portion in which a diameter of a connection portion with the side frame is larger than a vicinity of a center portion. The thickness of the main part of the hollow part is substantially 10
A cross member for automobiles, which is not more than mm and formed of a casting. 2. The cross member for an automobile according to claim 1, wherein said hollow portion has a rectangular shape. 3. The cross member for an automobile according to claim 1, wherein the hollow portion has a circular shape. 4. The automobile cross member according to claim 1, wherein said hollow portion is a combination of a square and a circle. 5. The cross member for an automobile according to claim 1, wherein a wall is provided at the central portion. 6. The cross member for an automobile according to claim 1, wherein the cross member for an automobile is made of a spheroidal graphite cast iron material. 7. The vehicle cross member according to claim 1, wherein the cross member is made of an aluminum alloy.
An automobile cross member according to any one of the preceding claims. 8. The method according to claim 1, wherein the aluminum alloy is (JIS) AC
The automobile cross member according to claim 7, wherein the cross member is 4CH.