JP2010070128A - Deck pipe molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out the material replacement of a deck pipe for achieving both weight reduction and high rigidity. <P>SOLUTION: In a molding method for a deck pipe to be arranged in a vehicle widthwise direction of an automobile, after heating a bar-shaped solid base material, a hollow pipe 2 is formed by extruding the central part of the base material by extrusion molding such that the board thickness of a section becomes uneven (first step), and after that, the heated hollow pipe 2 is loaded to a mold 3 to form a cross-sectional shape with different diameters in a longitudinal direction by bulging (second step). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for forming an automobile deck pipe.

  Generally, an engine room formed at the front part of the automobile and a vehicle room formed at the rear part thereof are partitioned by a dash panel disposed in the left-right direction. Further, a deck cross member for attaching a steering column, audio, or the like or supporting the instrument panel is provided in the left and right direction from the dash panel. This deck cross member is mainly composed of a deck pipe formed of a hollow pipe, and various brackets for attaching a steering column, an audio, etc. are welded to the deck pipe and assembled.

The deck pipe is attached to the vehicle body by fastening the left and right ends of the deck pipe to the left and right front pillars with bolts or welding (see, for example, FIG. 1 of Patent Document 1). .
JP 2000-128025 A

By the way, although such a deck pipe is generally made of iron, the iron deck pipe is heavy, and in recent years, attempts have been made to replace the material from the viewpoint of weight reduction. In this case, it is conceivable to use an aluminum material as a material that is relatively inexpensive and has a large weight reduction effect. However, simply replacing iron with aluminum causes the following problems.
First, when an aluminum pipe is simply applied instead of a conventional iron deck pipe, the vibration around the steering (vibration transmitted to the steering column) increases because aluminum has lower rigidity than iron. Therefore, in order to suppress vibration, it is necessary to increase the diameter of the deck pipe on the driver's seat side.

  In this case, if the deck pipe is formed by general extrusion molding, the deck pipe can be formed only in a certain cross-sectional shape in the longitudinal direction, so the passenger seat side has the same diameter as the driver seat. However, since the required rigidity is lower on the passenger seat side than on the driver seat side, the required rigidity can be ensured with the aluminum deck pipe without changing the outer diameter. For this reason, if the deck pipe on the driver's seat side has a large diameter for the purpose of suppressing the vibration of the steering column, there is a problem in that the passenger seat side becomes unnecessarily large in the extrusion and increases the weight.

  On the other hand, when replacing an aluminum deck pipe with a vehicle that has been designed on the assumption of an iron deck pipe until now, it is necessary to consider other mounting parts and layout without changing the outer diameter. There is a demand for material replacement. This is because if there is no change in the outer diameter, design changes to the parts around the deck pipe are not necessary, and the existing parts can be used. For this reason, at least the passenger seat side should have the same outer diameter as the steel deck pipe.

  Therefore, it is conceivable to form a small-diameter passenger-side deck pipe and a large-diameter driver's deck pipe with aluminum, and connect these two deck pipes by welding. Insufficient rigidity occurs at the joint, and the required rigidity and strength cannot be ensured. A fastening structure using bolts or the like is also conceivable. However, when configured in this manner, the weight increases and the weight reduction effect decreases.

Further, the deck pipe is required to have a high bending rigidity on the front side of the vehicle in consideration of the front collision of the vehicle, but the rigidity is not required to be higher on the front side in the vehicle rear side and the vertical direction. Therefore, there is also a demand to change only the bending rigidity with respect to the front side of the deck pipe by changing the cross-sectional shape of the deck pipe between the front side of the vehicle and other directions.
The present invention was devised in view of such problems, and is formed with deck pipes having different diameters in the length direction so as to obtain the required rigidity while reducing the weight, and is higher than the front collision. It is an object of the present invention to provide a deck pipe forming method capable of obtaining rigidity.

  The deck pipe forming method of the present invention is a method of forming a deck pipe disposed in the vehicle width direction of an automobile, and the plate thickness of the cross section becomes non-uniform after heating a solid bar-shaped base material. A first step of forming the hollow pipe by extruding the central portion of the base material by extrusion molding, and a cross section in which the hollow pipe is carried into a mold in a state where the base material is heated and the diameter is different in the longitudinal direction by bulge forming And a second step of forming a shape.

In addition, it is preferable to perform the extrusion molding in the first step and the bulge molding in the second step continuously.
In the first step, the hollow pipe is preferably extruded so that the thickness of the deck pipe in the vehicle vertical direction is smaller than that in the front-rear direction.
In the second step, preferably, the hollow pipe is compressed in the axial direction to enlarge the diameter of the hollow pipe, and then a high-pressure fluid is supplied into the mold to form the deck pipe.

  In the second step, it is preferable to form the driver seat side in a shape having a different diameter in the longitudinal direction so that the driver seat side has a larger cross-sectional shape than the passenger seat side.

  According to the deck pipe molding method of the present invention, by performing extrusion molding and bulge molding in succession, “high degree of freedom of cross-sectional shape” which is an advantage of extrusion molding and longitudinal length which is an advantage of bulge molding. `` High degree of freedom in shape in the direction '' can be utilized at the same time, and since welding is not used, the rigidity of the joint of the deck pipe on the driver's side and passenger's side can be secured without increasing weight, and it is lightweight. In addition, there is an advantage that a highly rigid deck pipe can be realized. Therefore, a deck pipe having a high rigidity can be realized by forming deck pipes having different diameters in the length direction.

In particular, by continuously performing the extrusion molding in the first step and the bulge molding in the second step, the base material heated at the time of extrusion molding can be bulged at a high temperature as it is. In particular, there is an advantage that hot bulge forming can be performed without heating, and complicated forming can be performed at low cost.
In addition, by making the thickness of the deck pipe in the longitudinal direction of the vehicle thicker than in the vertical direction, high bending rigidity can be obtained in consideration of the front collision, and in the vertical direction of the vehicle, the thickness is made relatively thin. There is an advantage that the weight can be reduced.

Further, in bulge forming, the hollow pipe can be compressed in the axial direction and then expanded to prevent the thickness from being reduced due to forming.
In addition, by forming the cross-sectional shape of the deck pipe on the driver's seat side to have a larger diameter than the passenger seat side, it is possible to increase the rigidity on the driver seat side where high rigidity is required. Therefore, the vibration of the steering column can be suppressed on the driver's seat side, and the same diameter as the conventional one can be used on the passenger seat side, so that the same parts as before replacing the material can be used. There is an advantage that it is not necessary.

  Further, by using aluminum as the base material, it is possible to provide a relatively inexpensive and highly rigid deck pipe.

  Hereinafter, a method for forming a deck pipe according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing a shape of a base material of a deck pipe before and after extrusion molding. The figure which shows the shape before extrusion molding, (b) is the figure which shows the shape after extrusion molding, FIG. 2, FIG. 3 is a figure explaining the state before shaping | molding by bulge shaping | molding, Comprising: FIG. 2 is a cross-sectional view taken along the line A-A, FIG. 3B is a cross-sectional view taken along the line BB in FIG. 2, and FIGS. 4 is a cross-sectional view taken along line A′-A ′ of FIG. 4, and FIG. 5B is a cross-sectional view taken along line B′-B ′ of FIG. 4.

  A base material (billet) 1 shown in FIG. 1 is a solid rod-like metal, and cast aluminum is applied in this embodiment. And the hollow pipe 2 is shape | molded from this preform | base_material 1, and finally the cross section of the direction orthogonal to a longitudinal direction has a different shape (or different outer diameter) as shown to Fig.5 (a), (b). It is designed to be processed into a deck pipe. In the following, the base material is denoted by reference numeral 1 and the hollow pipe is denoted by reference numeral 2 in accordance with the degree of processing.

Hereinafter, a specific forming procedure of the deck pipe will be described. The deck pipe is mainly formed by continuously performing extrusion molding (first process) and bulge molding (second process).
Of these, the pipe 2 having a uniform outer diameter in the longitudinal direction and a non-uniform thickness is formed by extrusion molding. Before the extrusion, the following work is performed as a preparation step.
First, the base material 1 is heated in a furnace at a predetermined temperature (about 500 ° C.) for about 3 hours. By performing such a heat treatment, the composition of the base material 1 is made uniform and the strength quality is improved. The melting point of aluminum is about 660 ° C. Next, the base material 1 is cut into a required length. Of course, if the base material 1 is cut from the beginning assuming the length of the deck pipe as a finished product, this cutting operation is not necessary.

Next, extrusion molding is performed. In extrusion molding, the base material 1 is first heated again in order to facilitate extrusion. The temperature of the base material 1 at this time is preferably heated to about 450 to 500 ° C. Therefore, in the case where the heat treatment in the preparation step is shifted to extrusion molding continuously, the heat treatment for extrusion molding can be omitted.
And at the time of extrusion molding, extrusion molding is performed by pressing a mold | type by applying a type | mold to the center side in the state which hold | maintained the base material 1 with the jig | tool. Thereby, the hollow pipe 2 is formed. Here, in the present embodiment, as shown in FIG. 1B, in the cross section orthogonal to the longitudinal direction of the base material, the plate thickness is not constant (variable plate thickness), and the direction in which high bending rigidity is not required. On the other hand, extrusion molding is performed so that the plate thickness is as thin as possible and the plate thickness is increased in the direction in which high bending rigidity is required.

Specifically, as shown in FIG. 1B, the sheet is formed so that the plate thickness is large in the vehicle longitudinal direction and the plate thickness is thin in the vertical direction. Further, in the longitudinal direction of the vehicle, the plate thickness in the direction toward the front of the vehicle is formed thicker in consideration of the front collision of the vehicle.
Next, it is transferred to the next step by a transfer mechanism (not shown), and the hollow pipe 2 is placed on the mold 3 shown in FIG. Here, in the present embodiment, after completion of the first step (extrusion molding), heat is applied to the base material 1 by performing the second step (bulge forming) continuously before the base material 1 cools. Hot bulge forming is performed without any problems.

  That is, the bulge forming as the second step is hot bulge forming in which the base material 1 is heated to around 400 ° C. to improve the formability of the base material 1. In addition, since the process of heat treatment is added in normal hot bulge forming, the consumption of time and energy is greatly increased, but in this embodiment, the extrusion forming in the first step and the bulging forming in the second step By continuously performing the above, the base material 1 heated at the time of extrusion molding can be bulge-molded in a high temperature state as it is. Therefore, hot bulge molding can be performed without particularly heating the base material 1 during bulge molding, and complicated molding can be performed at low cost.

  Here, in this bulge molding, as shown in FIG. 2, the mold 3 is formed in a shape having a different diameter in the longitudinal direction so that the driver seat side has a cross-sectional shape with a larger diameter than the passenger seat side. It has become. More specifically, the shape of the mold 3 is designed such that the finished product (deck pipe) after molding has an outer diameter that can reliably suppress or prevent vibration of the steering column on the driver's seat side. Also, on the passenger seat side, the shape is designed to have the same outer diameter as the deck pipe before material replacement.

  The mold 3 is configured differently on the left half driver seat side and the right half passenger seat side in FIG. Of these, the driver seat side and the passenger seat side are the same in that the mold 3 is divided into two parts, but the driver seat side is fixed when the mold 3 is molded, and when the hollow pipe 2 is installed and when the mold is removed. It is configured to open and close only. The mold 3 on the driver's seat side is formed to have a diameter slightly larger than the outer diameter of the base material after extrusion molding. Further, as shown in FIG. 3 (a), a plurality of dies 4 are provided in the horizontal direction in addition to the upper and lower dies, and a complicated shape is formed according to the shape of the dies 4 in the horizontal direction. Be able to. Note that as the cross-sectional shape after molding becomes more complex, the number of molds 4 to be pulled out in the lateral direction increases. On the other hand, as shown in FIG. 3B, the mold 3 on the passenger seat side is configured to be compressed in the vertical direction during molding, and when the upper and lower molds 3 come into contact with each other, the upper and lower molds are arranged. The inside of 3 is sealed.

  Next, a specific procedure of bulge forming will be described. After placing the hollow pipe 2 on the mold 3, first, compressive stress is applied to the hollow pipe 2 in the axial direction from both ends, and the base material 1 is pivoted. Compress in the direction (see FIG. 2). As a result, the hollow pipe 2 (base material 1) is contracted in the axial direction, and is expanded in the radial direction by this amount (expanding), thereby increasing the plate thickness as a whole. This is for offsetting the reduction in sheet thickness due to subsequent bulge forming.

And after completion | finish of the said pipe expansion process, a pressurized fluid is supplied to the metal mold | die 3 which sealed, and a load is given to the hollow pipe 2. FIG. At this time, pressure is applied in the radial direction from the center of the hollow pipe 2 by the pressurized fluid flowing into the inner diameter side of the hollow pipe 2, and as a result, the hollow pipe 2 bulges to the inner shape of the mold 3. It is designed to shape along.
Here, on the driver's seat side, by forming the shape while gradually pulling out the lateral die 4, finally, as shown in FIG. A deck pipe having a large cross-sectional shape is formed.

On the passenger side, as shown in FIG. 4, the pressurizing fluid is decompressed while compressing the mold 3 from above and below to form a final shape. A pipe 5 having a small-diameter cross-sectional shape as shown in b) is formed.
A deck cross member assembly is completed by attaching various brackets to the deck pipe.

  As described above in detail, according to the deck pipe molding method according to an embodiment of the present invention, by performing extrusion molding and bulge molding continuously, the advantage of extrusion molding is “the degree of freedom of the cross-sectional shape. The height and the advantage of bulge forming, which is the “high degree of freedom in shape in the longitudinal direction”, can be utilized simultaneously, and a lightweight and highly rigid deck pipe can be formed. Therefore, it is possible to simultaneously improve rigidity and reduce weight while forming deck pipes having different diameters in the length direction.

In particular, by continuously performing the extrusion molding in the first step and the bulge molding in the second step, the base material heated at the time of extrusion molding can be bulged at a high temperature as it is. In particular, hot bulge molding can be performed without heating, and complex molding can be performed at low cost.
In addition, by making the thickness of the deck pipe in the longitudinal direction of the vehicle thicker than in the vertical direction, high bending rigidity can be obtained in consideration of the front collision, and in the vertical direction of the vehicle, the thickness is made relatively thin. Weight reduction can be achieved.

  In the bulge forming, the hollow pipe 2 is formed by compressing in the axial direction and expanding the diameter, thereby preventing a reduction in the plate thickness due to the bulge forming. In addition, by forming the cross-sectional shape of the deck pipe on the driver's seat side to have a larger diameter than the passenger seat side, it is possible to increase the rigidity on the driver seat side where high rigidity is required. Therefore, the vibration of the steering column can be suppressed on the driver's seat side, and the same diameter as the conventional one can be used on the passenger seat side, so that the same parts as before replacing the material can be used. There is an advantage that it is not necessary. Further, by using aluminum as the base material, it is possible to provide a deck pipe that is relatively inexpensive and can be reduced in weight.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, a lightweight metal other than aluminum may be applied as the base material, and the plate thickness may be uniformly formed as long as the required bending rigidity can be ensured.

It is a typical perspective view which shows the shape of the preform | base_material of the deck pipe before and behind the extrusion molding of the deck pipe shaping | molding method which concerns on one Embodiment of this invention, Comprising: (a) The figure which shows the shape before extrusion molding, (b) These are figures which show the shape after extrusion molding. It is a figure explaining the state before the bulge shaping | molding of the deck pipe shaping | molding method which concerns on one Embodiment of this invention. It is a figure explaining the state before the bulge shaping | molding of the deck pipe shaping | molding method which concerns on one Embodiment of this invention, Comprising: (a) is the AA cross section of FIG. 2, (b) is the BB cross section of FIG. FIG. It is a figure explaining the state after bulge forming of the deck pipe forming method concerning one embodiment of the present invention. 5A and 5B are diagrams for explaining a state after bulge forming of the deck pipe forming method according to the embodiment of the present invention, in which FIG. 4A is a cross-sectional view taken along line A′-A ′ of FIG. 4, and FIG. It is a figure which shows a B 'cross section.

Explanation of symbols

1 Base material 2 Hollow pipe 3 Mold 4 Lateral mold

Claims (6)

A method of forming a deck pipe disposed in the width direction of an automobile,
A first step of forming a hollow pipe by extruding the central part of the base material by extrusion molding so that the thickness of the cross-section becomes non-uniform after heating the solid bar-shaped base material;
The hollow pipe is carried into a mold in a state where the base material is heated, and includes a second step of forming cross-sectional shapes having different diameters in the longitudinal direction by bulge forming.
A deck pipe molding method characterized by the above. The deck pipe molding method according to claim 1, wherein the extrusion molding in the first step and the bulge molding in the second step are continuously performed. 3. The deck according to claim 1, wherein in the first step, the hollow pipe is extruded so that the thickness of the deck pipe in the vehicle vertical direction is thinner than the thickness in the front-rear direction. Pipe forming method. In the second step, the hollow pipe is compressed in the axial direction to increase the diameter of the hollow pipe, and then a high-pressure fluid is supplied into the mold to form the deck pipe. Item 4. The deck pipe forming method according to any one of Items 1 to 3. 5. In the second step, the driver seat side is formed into a shape having a different diameter in the longitudinal direction so as to have a larger cross-sectional shape than the passenger seat side. The deck pipe forming method according to the above. The deck pipe forming method according to any one of claims 1 to 5, wherein the base material is aluminum.

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