KR101837383B1 - Method for vehicle Rear Cross Member manifacturing using roll forming, preforming, hot blowing forming and DIfferent Thickness Aluminum Plate - Google Patents

Abstract

The present invention relates to a method of fusing roll forming, pre-forming and hot blowing forming and a method for manufacturing a rear cross member using an aluminum plate with a different thickness for a vehicle. More specifically, the method for manufacturing a rear cross member using an aluminum plate with a different thickness for a vehicle comprises: a tube expansion designing step of generating tube expansion information of each part of a product, which includes a tube expansion rate and thickness information of each part of the product; a step of manufacturing a raw material having a plate shape with a different thickness by a tailor welded blank (TWB) method based on the tube expansion information; a step of forming the raw material into a roll-shape through a roll forming process; a step of manufacturing a tube body by performing high frequency welding to and cutting the raw material to be formed in the roll shape; a step of pre-forming the tube body through a pre-forming device; a step of heating the pre-formed tube body; and a step of manufacturing a rear cross member for a vehicle by performing a hot blowing forming process to the tube body by a hot blowing forming device. There is an effect to improve collision impact absorption performance by sequentially absorbing collision energy.

Description

A method of manufacturing a rear cross member for a vehicle using a roll foaming, a preforming and a hot air pressure forming fusion method, and a method for manufacturing a rear cross member for a vehicle using a dual thickness aluminum plate.

Roll forming, preforming and hot air pressure molding fusion method, and a manufacturing method of a rear cross member for a vehicle using a different thickness aluminum plate.

Generally, a rear cross member for a vehicle is manufactured by fabricating a cross member and a side member for manufacturing a finished part, and then assembling the manufactured parts .

FIG. 1A is a plan view of a general rear cross member for a vehicle, and FIG. 1B is an exploded perspective view of a cross member and a side member constituting the rear cross member for a vehicle shown in FIG. 1A.

1A and 1B, a rear cross member 1 is formed by combining a tubular cross member 10 and a side member 20, in which a cross member 10 and a side member 20 are manufactured respectively, Welded joints.

As shown in FIG. 1B, the cross members 10 and the side members 20, which are box-type components, are completed by welding and assembling the individual articles 10a, 10b, 20a, and 20b.

However, since the box-type chassis component manufactured by such a welding assembly process necessarily involves a welding process, there is a problem that corrosion occurs in a welded portion after a lapse of a predetermined time.

1B, the cross members 10 and the side members 20, which are box-type type parts, have such a shape feature that the length of the joined portion to be joined is long, and the overlapping portions of the end portions of the base material, There is a problem in that the weight is increased and the cost is not economical.

In recent years, a hydroforming method has been applied to a process for producing a box-type part to solve such a problem.

FIG. 2 shows a schematic view of a general hydroforming method.

As shown in FIG. 2, the hydroforming method is a method in which a plate-shaped raw material is formed into a pipe shape by a forming method, a raw material formed in a tubular shape is mounted inside a forming tool, And a strong pressure is applied by using a fluid or a liquid to form a tubular box-type part.

As shown in FIG. 1B, the method of machining and welding the tubular raw material into the shape of a C has two joints arranged in parallel in the axial direction, while the hydroforming method shown in FIG. 2 is a method in which, Since the welding length is reduced to half and the welding part is linear, the welding time is short and the welding quality is maintained uniformly because the welding difficulty is low.

However, the hydroforming method shown in Fig. 2 means that the portion A where the forming is performed is expanded, and the length of the outer periphery of the side end face of the portion is longer than the side end face of the portion B that is not formed It becomes longer than the length of the outer periphery.

Therefore, there arises a problem that the thickness at the A site becomes thinner than the thickness at the B site.

Korea Patent Publication No. 2014-0001720 Korean Patent Publication No. 2013-0030479

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a method of manufacturing a rear cross member, There is provided a method of manufacturing a rear cross member for a vehicle that can uniformly support a load or a load applied from the outside by uniformizing the thickness of each portion irrespective of a forming region and a rear cross member product to which the manufacturing method is applied .

According to an embodiment of the present invention, there is provided a manufacturing method of a rear cross member for a vehicle, which improves welding corrosion problems by applying a new fusion method combined with a roll forming method, a row heating method and a hot air pressure molding method, And a rear cross member product for a vehicle to which the manufacturing method is applied.

Further, according to an embodiment of the present invention, a method for manufacturing a rear cross member for a vehicle and a method for manufacturing the rear cross member, which can increase the moldability of a vehicle part at the closed end of various pieces of one piece by preforming the tube body before heating and hot- The present invention provides a rear cross member product for a vehicle to which the method is applied.

According to an embodiment of the present invention, an aluminum alloy can be applied as a raw material to improve the fuel efficiency by weight reduction. According to another embodiment, a boron steel plate or a boron steel plate of a different thickness securing an elongation rate, The present invention provides a manufacturing method of a rear cross member for a vehicle and a rear tire of a vehicle to which a manufacturing method thereof is applied by adopting a tailored blank by applying TWB to a general steel plate as a material, The object of the present invention is to provide a cross member product.

Further, according to the embodiment of the present invention, it is possible to easily assemble and disassemble the apparatus of the punching means while adjusting or maintaining the centering in the assembly of the punch, and the punch replacement is smoothly performed The present invention provides a method for manufacturing a closed-end vehicle part and a vehicle part to which the manufacturing method is applied, in which ultimately improving precision and device operation of a material based on hot air pressure molding.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

According to an aspect of the present invention, there is provided a method for manufacturing a rear cross member for a vehicle, the method comprising: a step of calculating, based on linearity, thickness reduction rate, weight reduction, An enlargement design step of generating enlargement information for each part of the product including the product; A step of fabricating a heterogeneous thick plate-shaped raw material, which is manufactured by a tailor welded blank (TWB) method based on the expanded information; Molding the raw material into a roll form by a roll forming process; A step of producing a tube by welding and cutting a raw material molded in a roll shape by high frequency welding; Preforming the tubular body through a preforming device; Heating the preformed tube; A method of manufacturing a rear cross member for a vehicle, comprising the steps of: performing a hot air pressure forming process on a tubular body by a hot air pressure forming apparatus to manufacture a rear cross member for a vehicle, wherein the step of manufacturing a rear cross member for a vehicle comprises the steps of: Providing a punch device on each end of the tubular body to seal the tubular body; Injecting a fluid into the tubular body through a pressurized fluid inlet pipe provided in the punching apparatus and pressurizing the pressurized fluid; And a step of cooling the cooling medium by injecting the cooling medium through the quenching tube provided in the punching apparatus to the inside of the tube body after the completion of the molding, wherein the preforming step includes the step of projecting the tube end of the tube body longer than the length of the mold from the lower mold Mounting in one state; Gradually pushing the sealing punch to the tube end of the tube body while injecting the pressurized fluid into the tube body through the inside of the sealing punch to load a predetermined pressing force; Filling the tubular body with a pressurized fluid to load the tubular body up to a predetermined internal pressure, lowering the upper mold and fastening the mold while the internal pressure and the pressing force are applied; And a step of raising the internal pressure in the tubular body. The present invention also provides a method of manufacturing a rear cross member for a vehicle using a roll foaming, a preforming, and a hot air pressure molding fusion method and a dual thickness aluminum plate.

Further, in one embodiment, the thickness of the flat plate-like raw material is set so that the thickness along the longitudinal direction of the rear cross member of the automobile is minimized after being molded in the step of manufacturing the rear cross member for a vehicle, And the thickness of the metal plate is varied.

Further, in one embodiment, the step of manufacturing the rear crossmember for a vehicle includes the steps of: providing a mold having a heating means capable of locally heating the tubular body, using a mold having a heating means, It is possible to diversify the heating region used.

Further, in one embodiment, it is more preferable to heat the temperature of the low-expansion rate portion of the tube to a temperature higher than the temperature of the high-temperature portion of the tube.

In one embodiment, the tubular body further includes a body fixing member having a mounting groove recessed into the inside of the tubular body at both sides thereof, the body fixing member having a U-shaped shape and having opposite end portions fitted in the mounting groove and having a fastening hole formed on one side thereof, And the fastening hole is screwed to a specific position of the vehicle body to which the pipe body is to be mounted.

 According to one embodiment of the present invention, by applying the hot air pressure molding method using aluminum plates of different thicknesses, it is possible to uniformize the thickness of each part regardless of the molding position after molding the rear cross member for a vehicle, The load or the load can be uniformly supported

In addition, according to one embodiment of the present invention, a new fusion method combining roll forming, line heating, and hot air pressure molding method is applied to improve the welding corrosion problem and improve the corrosion resistance

In addition, according to the embodiment of the present invention, the preforming is performed before tube heating and hot air pressure forming, and thus the moldability of the vehicle parts on the closed end faces of various shapes can be increased

According to an embodiment of the present invention, an aluminum alloy can be applied as a raw material to improve the fuel efficiency by weight reduction. According to another embodiment, a boron steel plate or a boron steel plate of a different thickness securing an elongation rate, By adopting a custom-made blank by applying TWB to the general steel sheet as the material, the collision energy is successively absorbed and the collision absorbing performance can be improved

Further, according to the embodiment of the present invention, it is possible to easily assemble and disassemble the apparatus of the punching means while adjusting or maintaining the centering in the assembly of the punch, and the punch replacement is smoothly performed , Which ultimately has the effect of improving the machining precision and the device operability of a material based on hot air pressure molding

It should be understood, however, that the effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further understand the technical idea of the invention. And should not be construed as interpreted.
1A is a plan view of a general rear crossmember for a vehicle
Fig. 1B is an exploded perspective view of a cross member and a side member constituting the rear cross member for a vehicle shown in Fig. 1A
2 is a schematic view of a general hydroforming process;
3 is a flow chart of a roll-forming, pre-forming and hot-air-pressure molding fusion method and a method of manufacturing a closed-end vehicle component using a two-
FIG. 4 is a view illustrating a process of laser welding a steel plate having different thicknesses according to an exemplary embodiment of the present invention,
5 is a process flow diagram illustrating a roll forming process according to an embodiment of the present invention,
FIG. 6 is a conceptual view illustrating a roll forming system according to another embodiment of the present invention,
Fig. 7 is an explanatory view of a process for preforming a tube manufactured by roll forming according to an embodiment of the present invention. Fig. 7A shows a state in which the tube is mounted on the lower mold, Fig. 7B shows a state in which the tube FIG. 7C shows a state in which the upper mold is lowered and press-worked under a state in which the sealing punch is pressed against the tube end to apply the internal pressure, FIG. 7D shows a state in which the internal pressure is stepped up to pre-
FIG. 8 is a diagram showing a state in which a preformed tube is line-heated according to an embodiment of the present invention;
9A is an explanatory view of a step of hot air pressure forming processing according to an embodiment of the present invention. Fig. 9A shows a state in which punch means having a pressurized fluid inlet port and punch means having a cooling port seal both ends of the tube, FIG. 9C shows a state in which a pressurized fluid is discharged by opening the discharge control valve, FIG. 9D shows a state in which a cooling medium is injected into the tube through a cooling hole, and is cooled condition,
10 is a cross-sectional view of a hot air pressure molding apparatus using punch means having a cooling sphere and a pressurized fluid inlet according to another embodiment of the present invention;
11 is a cross-sectional view of a punching device according to an embodiment of the present invention,
12 is an exploded perspective view of a punching device according to an embodiment of the present invention,
13 is a front view of a punching device according to an embodiment of the present invention;
14 is a front view showing the fastening structure of the punch means and the second cylinder according to the embodiment of the present invention.
Fig. 15 is a cross-sectional view of a steel plate and a mold according to an embodiment of the present invention,
FIG. 16 is a cross-sectional view of a dual-thickness steel plate and a mold designed based on the vector direction of the expansion ratio and the expansion position according to an embodiment of the present invention
17 is a cross-sectional view of a hot air pressure forming process using a local expansion and local heating method in accordance with an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas. Also, the purpose or effect of the present invention should not be construed as limiting the scope of the present invention, since it does not mean that a specific embodiment should include all or only such effect.

The meaning of the terms described in the present invention should be understood as follows.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include "or" have "are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present invention.

3 is a flow chart of a method of manufacturing a closed end vehicle component using a roll forming, preforming, and hot air pressure molding fusion technique.

3, a method of manufacturing a closed end vehicle component according to an embodiment of the present invention includes the steps of: firstly, designing a product thickness of the plate-shaped raw material through a product design step (S1) and an expansion design step (S2) The design (S3) proceeds.

The expansion design (S2) takes into account the moldability, thickness reduction rate, expansion ratio and weight reduction of the designed product. That is, the thickness information of each portion of the plate-like raw material so that each portion of the plate-like raw material matched to each portion of the final product has a different thickness structure so that the thickness of the product after the final molding corresponds to the design value The thickness of the thin-walled structure is set to be greater than the thickness of the thin-walled structure.

According to the different thickness design, the flat foaming device 10 is manufactured (S4). In a specific embodiment, a forming device 10 made of boron-steel or the like is used. In the concrete embodiment, the forming device 10 made of boron-steel or the like is used do.

The flat plate forming apparatus 10 is put into a roll forming apparatus 10, and is manufactured in a roll form by a roll forming method. The ends are welded to each other by high frequency welding and cut to produce a tubular body 6 (S5).

Then, the tube 6 manufactured by the roll forming method is preformed (S6). The preformed formed article is heated to 850 to 1000 DEG C in about 10 seconds by a line heating method (S7).

Then, the heated tube body 6 is put into a hot-air pressure molding apparatus and is manufactured in a desired shape by the hot air pressure forming step (S8). Finally, the closed end vehicle part is manufactured by the laser cutting process S9.

Hereinafter, the above-mentioned steps will be described in more detail. First, in the step of manufacturing the plate-like raw material, the composition of the plate-like raw material is not limited in principle, but it is preferably composed of aluminum, an aluminum alloy, a steel plate, a boron steel plate and the like.

When aluminum alloy is used, aluminum alloy has excellent moldability at high temperature, and it has strength suitable for automobile parts, and it is difficult to form due to cracking in the high temperature molding of existing aluminum alloy. Al- Mg alloy, that is, the main components of the aluminum alloy are 3.1 to 3.4 wt% of Mg, 0.5 to 0.6 wt% of Mn, 0.2 to 0.35 wt% of Cr, 0.1 to 0.2 wt% of Ti, and other unavoidable components are individually 0.1 wt% %, And the sum is made to be 0.25 wt% or less, and the balance is made of Al.

Here, Mg is solid solution hardening, which improves the strength of the matrix and increases the strength as the content increases. However, when the content is more than 3.5 wt%, Mg decreases the extrudability, while Mn has the effect of grain refinement through formation of compounds such as Mn3Al The strength is improved, but when it exceeds 0.6 wt%, the elongation is decreased.

Cr has an effect of suppressing the formation and growth of the recrystallized layer to improve the high-temperature formability. However, when 0.36 wt% or more, it generates a large intermetallic compound and rather lowers the high-temperature formability. Ti is a component The effect of reducing the size of the large intermetallic compound due to the addition of Cr and the like can be obtained, but when the content is more than 0.2 wt%, the extrudability is lowered.

As will be described later, when the tube 6 is constituted by a steel tube by roll forming, for example, the steel sheet forming apparatus 10 can be formed, for example, in a range of about 0.22 wt% (weight ratio) to about 0.28 wt% Of carbon (C), from about 0.28 wt% to about 0.32 wt% carbon, or from about 0.32 wt% to about 0.38 wt% carbon. For example, steel tubes containing carbon in the range of about 0.22 wt% to about 0.28 wt% can be applied to compact cars. Steel pipes containing from about 0.28 wt.% To about 0.32 wt.% Carbon are applicable to medium-sized vehicles. Steel pipes containing carbon in the range of about 0.32 wt% to about 0.38 wt% are applicable to large vehicles.

The steel sheet may also include silicon (Si) ranging from about 0.10 wt% to about 0.25 wt%, manganese (Mn) ranging from about 1.00 wt% to about 1.60 wt%, phosphorus ranging from about 0.001 wt% to about 0.03 wt% P), sulfur (S) in the range of about 0.001 wt% to about 0.02 wt%, and boron (B) in the range of about 0.001 wt% to about 0.005 wt%. For example, the steel sheet may include manganese (Mn) and silicon (Si) so that the manganese (Mn) / silicon (Si) has a range of 6 to 9. If it is outside the above range, a high melting point oxide due to manganese (Mn) and silicon (Si) may be generated.

The steel sheet may also include chromium (Cr) in the range of about 0.001 wt% to about 0.05 wt%, molybdenum (Mo) in the range of about 0.001 wt% to about 0.05 wt%, and nickel in the range of about 0.001 wt% to about 0.05 wt% Ni) may be further included. The steel sheet may also include chromium (Cr) in the range of about 0.001 wt% to about 0.01 wt%, molybdenum (Mo) in the range of about 0.001 wt% to about 0.01 wt%, and nickel in the range of about 0.001 wt% to about 0.01 wt% Ni) may be further included.

Such chromium (Cr), molybdenum (Mo), and nickel (Ni) can perform the function of improving the hot gas forming characteristics of the steel pipe 10 during hot gas forming.

Further, in still another embodiment of the present invention, the plate-form forming apparatus 10 may be constituted by a boron steel plate. The boron steel sheet preferably has a ferrite metal structure with an elongation of 30% or more and less than 50%.

In another embodiment of the present invention, the flat foaming apparatus 10 may be manufactured by applying a tailor-welded blank (TWB) technique to produce a custom blank with a material having different materials, thicknesses, and strengths, It may be constructed by welding a plurality of boron steel sheets having different thicknesses and having a ferrite metal structure with an elongation of 30 to 50%.

FIG. 4 is a view illustrating a process of laser welding a steel plate of different materials according to an exemplary embodiment of the present invention, which is manufactured from TWB and roll-formed into a tube 6.

For example, as shown in Fig. 4, different types of blanks (B1, B2, B3) for preparing vehicle parts are prepared from a general steel plate of 1.4t securing elongation and a boron steel plate of 1.2t and 1.8t To prepare the blank material. At this time, the boron steel sheet has a ferrite metal structure whose elongation percentage is 30% or more.

Then, considering the impact energy absorbing directionality of the vehicle parts, the 1.4t general steel blank B1 and the 1.2t and 1.8t boron steel plate blank B2 and B3 are arranged in order and are wound along each tailor weld line TW The laser beam LB is irradiated and laser welding is performed to produce a custom blank. As will be described later, the flat plate is formed into a tube 6 by a roll forming process, and then a tube body (not shown) is formed by laser welding the laser beam LB along the weld line W, 6).

Next, a method of forming the flat plate-like raw material into the tube body 6 by the roll forming process will be described. 5 is a flowchart illustrating a roll forming process according to an embodiment of the present invention. The order of the process steps of the manufacturing method of FIG. 5 is illustrative, and the case of being performed in a different order is also included in the technical idea of the present invention.

As shown in Fig. 5, the method of manufacturing the tube 6 by roll-forming may include several steps. Specifically, a steel plate as a flat plate-like raw material is prepared, the steel plate is formed into a semicircular steel material by using a black down roll, the semicircular steel material is formed into a quadrangular steel material by using a pin pass roll, The steel pipe is formed by welding using a roll. Then, the steel pipe is cut to form an individualized steel pipe.

The steel sheet as the forming device 10 may be a hot rolled coil wound and rolled. Alternatively, the steel sheet may be an individual steel sheet. The thickness of the steel sheet may vary. The steel sheet may be formed into a steel pipe by molding in several steps.

In the step of preparing the steel sheet, for example, a hot-rolled coil having a plate-like shape completed as a coil is prepared. The steel sheet may have a rectangular cross section as shown in Fig. In the step of forming the steel sheet into a semicircular steel material by using a black down roll, the steel sheet is rolled between black down rolls to form a semicircular steel material. The semicircular steel may have a semi-circular cross section as shown in Fig.

And, in the step of forming the semicircular steel material into a quarry-type steel material by using a pin pass roll, the semicircular material is rolled between fin passes and rolled to form a quarry-like steel material. The tubular steel may have a domed cross-section as shown in Fig. The solid line in the section shows the contact points of both ends of the tubular steel material.

And, in the step of forming the steel pipe by welding using the squeeze roll, the steel pipe may be formed by joining the steel pipe to the contact point while passing the sintered steel material through the squeeze rolls. The steel pipe formed by such welding may have a garden-shaped cross-section as shown in Fig. The welding can be performed in various ways, for example, electric resistance welding (ERW) using an induction coil method, or tungsten inert gas welding (TIG) using a gas welding method. The tubular steel may be locally heated by the induction coil before passing through the squeeze roll. Such heating may alleviate the thermal shock that may be caused to the quarry steel during the welding by the squeeze roll. After performing the welding step, the steel tube may be cooled using a liquid such as water or cooled using air. In the step of cutting the steel pipe to form an individualized steel pipe, the steel pipe is cut to a desired length by using a press apparatus, a welding apparatus, a cutter or a laser cutting apparatus to form the individualized steel pipe.

FIG. 6 shows a roll forming apparatus 10 according to still another embodiment of the present invention and a stepwise process conceptual diagram thereof. As shown in Fig. 6, the roll forming apparatus and its process are configured such that an uncoiler 11 for releasing a supplied steel sheet coil is disposed in front of the processing line, and proceeds to the uncoiling step.

A straightener 12 is provided behind the uncoiler 11 in the process direction to straighten a strip-shaped steel plate unwound from the uncoiler 11 to a steel plate panel. A piercing step may be performed at the rear of the straightener 12 in the process direction by providing a brake press 13 for forming holes 122 for various purposes on the steel panel supplied from the straightener 12. [

A roll forming unit 14 composed of at least ten roll formers (R1 to R7 (not shown)) is disposed behind the brake press 13 in the process direction, and the uncoiler 11, the straightener 12 ), And a brake press 13 to form a tube 6 having a closed end surface to be obtained by successively bending the steel sheet panel.

A laser welder 15 is provided behind the roll forming unit 14 to irradiate a welding portion of the tube 6 with a laser beam output from the laser oscillator 16 to advance the welding step.

Hereinafter, the step of preforming the tube 6 formed by the roll forming process will be described. This preforming step is performed before heating the tube body 6 by performing the preforming step to obtain the desired type of vehicle parts.

Fig. 7 is an explanatory diagram of a process for preforming a tube 6 manufactured by roll forming in accordance with an embodiment of the present invention. Fig. 7A shows a state in which the tube 6 is mounted on the lower mold, Fig. 7B Fig. 7C shows a state in which the upper mold is lowered and pressed by applying a sealing punch to the tube end to apply the inner pressure, Fig. 9D shows a state in which the inner pressure And the preforming is performed.

The tubular body 6 is mounted on the lower mold 21 of the preforming apparatus 20, as shown in Fig. 7A. At this time, the length of the tubular body 6 is set to be longer than the length of the lower mold 21, and the tubular end portion is mounted so as to protrude slightly from the end portion of the metal mold.

Here, the flat sealing punch 23 has a sealing surface 24 which is in contact with the tube end and is flat and has a larger area than that of the tube end. The sealing punch 23 is provided with a pressurized fluid inlet port 25. While the fluid is charged into the tubular body 6 through the pressurized fluid inlet port 25, the end of the tubular body 6 is pressed And is loaded with a predetermined pressing force. Further, the inside of the tube 6 is filled with a pressurized fluid and loaded to a predetermined internal pressure.

Next, as shown in Fig. 7C, the upper mold 22 is lowered and tightened while the sealing punch 23 is pressed against the tube end to apply the internal pressure in the tube 6. [ In this process, not only the end face which is in contact with the lower mold 21 and the upper mold 22, but also the protrusion which is not in contact with the mold is deformed while the end face is deformed. Further, since the mold clamping is performed while maintaining the internal pressure, no wrinkles or the like remain after the mold clamping.

If machining can be performed to the final part shape in the state of Fig. 7C, the machining is completed in Fig. 7C. However, if it is necessary to further increase the circumferential length, the internal pressure is further increased in this state to end machining. Then, as shown in Fig. 7D, the mold is finished in the shape along the inner surface of the mold, and the final preformed molded article is obtained.

Next, the step of heating the preformed tube 6 before performing the hot air pressure forming process will be described. In an embodiment of the present invention, a line heating method is applied. FIG. 8 is a block diagram showing a state in which a preformed tube 6 is line-heated according to an embodiment of the present invention.

As shown in Fig. 8, the voltage applying unit 40 is connected to one end of the preformed tube 6, and the other end is grounded. When voltage is directly applied to the tube 6 by the voltage applying unit 40, it is understood that the tube 6 generates heat and is heated. That is, a current flows through the tube 6 by the voltage application unit, and the tube 6 having the resistance value generates a string of as many as P = I ² R. Where I is the current flowing through the tube 6 and R is the resistance of the tube 6. [ The control unit controls the voltage applying unit 40 based on the temperature value measured by the temperature sensor to control the amount of current flowing through the tube body 6 to control the temperature of the tube body 6. [

According to the conventional heating means, it takes about 10 minutes to heat to a desired temperature (for example, 850 to 1000 ° C). However, when the line heating method according to the embodiment of the present invention is applied, And can be heated to a desired temperature.

Hereinafter, the hot air pressure forming process according to one embodiment of the present invention will be described. 9A and 9B are diagrams for explaining steps of hot air pressure forming processing according to an embodiment of the present invention. Fig. 9A is a cross-sectional view showing a punch means 60 having a pressurized fluid inlet port and a punch means 60 having a cooling port 9B shows a state in which both ends are sealed, FIG. 9B shows a state in which the pressurized fluid is pressurized into the tubular body 6 to be subjected to hot air pressure molding, FIG. 9C shows a state in which the pressurized fluid in the tubular body 6 is discharged And FIG. 9D shows a state in which the cooling medium is injected into the tube 6 through the cooling hole and cooled.

9, the hot air pressure forming apparatus 50 according to an embodiment of the present invention includes a mold having an upper mold 51 and a lower mold 52, a punch unit 60 having a pressurized fluid inlet, , A punching means (60) having a cooling port, and the like.

According to an embodiment of the present invention, after the heated tube 6 is provided inside the mold, the upper mold 51 and the lower mold 52 are fixed and the fluid is introduced and pressurized through the pressurized fluid inlet, 6) to be fitted to the mold. Then, after the fluid is introduced and molded, the cooling medium is discharged through the cooling hole and rapidly cooled, and the closed end chassis component is manufactured by the laser cutting process.

9A to 9D, in the hot-airpression molding apparatus 50 according to the embodiment of the present invention, heating means is provided in each of the upper mold 51 and the lower mold 52 of the mold So that the high temperature is maintained during the hot air pressure forming process (the temperature at which the martensitic transformation does not occur is maintained), and the cartridge 53 is applied as the heating means according to the specific embodiment. For example, the mold 53 is maintained at 400 to 600 ° C by the cartridge 53 provided in the mold.

In addition, a pressurized fluid inlet pipe 61 is used for forming the parts, and a fluid is introduced into the pressurized fluid to form a pressure of about 150 to 400 bar. Further, in order to increase the strength of the component, it is understood that the quenching tube 66 is disposed on the opposite side of the fluid compression tube, and cooling (martensitic transformation occurs) immediately after molding is possible.

In addition, when the fluid is introduced into the tube 6 by the pressurized fluid inflow pipe 61, the flow of the fluid is prevented so that the conical sealing structure is applied to the pressurized fluid inflow pipe 61 and the quench pipe 66 do. 9A, the ends of the inflow pipe 61 and the quench pipe 66 each have a tapered structure, and a plurality of step-shaped micro-stopping jaws are formed. It can be sealed so that the fluid does not flow out in the state of being pressurized.

The hot air pressure forming apparatus 50 according to an embodiment of the present invention may include a pressure sensor for measuring the internal pressure in real time and a temperature sensor for measuring the temperature, 9A to 9D are branched into a pressurized fluid supply pipe 62 and a fluid discharge pipe 63. An inflow control valve 64 is provided on one side of the pressurized fluid supply pipe 62, And a discharge control valve 65 is provided at one side of the discharge pipe 63. In addition, a cooling control valve 67 is also provided at one side of the quenching pipe 66.

9B, the cooling regulating valve 67 and the discharge regulating valve 65 are completely closed and the inlet regulating valve 64 is opened in the step of pressurizing and pressurizing the pressurized fluid. Accordingly, the pressurized fluid is introduced into the tube 6 through the pressurized fluid supply pipe 62 and the pressurized fluid inflow pipe 61, and the pressurized fluid is pressure-sensed in real time. At this time, The flow control valve 64 can be controlled to adjust the pressure.

When the pressurization and the hot air pressure molding are completed, the inflow control valve 64 is closed and the discharge control valve 65 is opened to discharge the fluid inside the molded body through the fluid discharge pipe 63. In this discharging process, the pressure sensor measures the pressure in real time. When the pressure becomes lower than the set specific pressure, the punch means 60 having the pressurized fluid inlet is driven backward, So that the cooling medium is injected into the molded body through the quenching tube 66 and cooled. A radial nozzle is provided at the end of the quenching tube 66 to rapidly cool the formed body.

10 illustrates a cross-sectional view of a hot air pressure forming apparatus 50 using a punch means 60 having a cooling sphere and a pressurized fluid inlet according to another embodiment of the present invention. The hot-airpression molding apparatus 50 shown in Fig. 10 has the same function and operation as those shown in Figs. 9A to 9D mentioned above, except that a punch 60 having a pressurized fluid inlet and a cooling port .

Hereinafter, the configuration of the punch device 100 according to an embodiment of the present invention will be described in more detail. 11 is a cross-sectional view of a punch device 100 according to an embodiment of the present invention. 12 is an exploded perspective view of a punching apparatus 100 according to an embodiment of the present invention. 13 shows a front view of a punching apparatus 100 according to an embodiment of the present invention. 14 is a front view showing the fastening structure of the punch means 60 and the second cylinder 140 according to the embodiment of the present invention.

11 to 12, the punching apparatus 100 according to an embodiment of the present invention includes punch fastening means 120 associated with the first cylinder 110 for punch operation, The punch means 60 is connected to the punch fixing means 120 through a second cylinder 140 connected to the first cylinder 110 Assembled to allow removal and attachment.

Therefore, the punching apparatus 100 according to the embodiment of the present invention is capable of facilitating the detachment and attachment of the punching means 60, in addition to the first cylinder 110 performing the punching operation Since the second cylinder 140 is further provided, it is very easy to replace the punch means 60 according to the processing conditions. This not only makes it possible to quickly and easily set the equipment in the hot-air pressure forming process, The punch means 60 can be easily replaced through the operation of the second cylinder 140 even if a replacement factor occurs.

11 to 12, the punching apparatus 100 according to the embodiment of the present invention is configured such that, in addition to facilitating the removal and attachment of the punching means 60, And punch centering means 130 provided to enable the centering of the punch means 60 to be maintained.

Thus, the punch device 100 of the present invention provides a device for maintaining the centering of the punch means 60 at least constant, in addition to providing ease of replacement of the punch means 60, It is possible to prevent defective machining, damage to equipment, molds, and the tube 6.

11 to 12, the first cylinder 110 and the second cylinder 140 of the punch device 100 according to the present invention are arranged such that the first cylinder 110 and the second cylinder 140, which implement the operation of the punching means 60, The cylinder 110 is assembled to the support 101 provided on both sides of the mold base and the second cylinder 140 is seated on the rod 111 of the first cylinder 110 and connected to each other.

13, the first cylinder 110, which is the main driving source of the apparatus, is assembled to the support 101, and the rod 111 (piston) of the first cylinder 110 is connected to the second cylinder 140 may be mounted. A separate connecting member having a cylinder seating groove 112 in which the second cylinder 140 is seated is connected to the rod 111 of the first cylinder 110 so that the supporting body 101 It may be provided inside.

Therefore, when the first cylinder 110 advances or retreats, the second cylinder 140 also advances or retreats. It is of course also possible to construct cylinder hydraulic or pneumatic systems.

11 and 12, the rod 111 of the first cylinder 110 passes through the support body 101 and is connected to the punch fastening means 120, which is a circular block, by bolts or the like, The punching means 120 is moved integrally when the cylinder 110 is moved forward or backward and consequently the punching means 60 is detachably provided as the second cylinder 140 to the punch fastening means 120 , The punch operation is implemented while advancing or retracting.

At this time, the first cylinder 110 is supported by a fixing body 113 (fixed disk) mounted on the front surface of the supporting body 101 so that only the rod 111 of the first cylinder 110 passes through the fixing body 113 .

The rod 141 of the second cylinder 140 passes through an opening formed at the center of the punch fastening means 120 and is fixed to the front end of the rod 141 of the second cylinder 140. [ The fastener 142 is assembled. 12 and 13, the punch means 60, which is detachably attached to the punch fastening means 120 via the second cylinder 140, has a flange 133 at its rear end, A punch body 134 integrally formed with the punch body 134 and a punch head 138 assembled at the front end of the punch body 134 to form a pressurized fluid syringe.

12 and 13, the punch body 134 and the rear end flange 133 of the present invention are integrally cut from the side portion of the side portion of the punch body 134 and the rear end flange 133, At the same time, a fixture insertion slot 135 into which a fixture 142 assembled to the distal end of the rod 141 is inserted is integrally formed.

The second cylinder 140 passes through the punch fastening means 120 and the rod 141 passes through and the fastener 142 assembled at the tip end of the rod 141 passes through the body 134 of the punch means 60 And is inserted and fastened together with the rod 141 into the provided insertion groove 135.

As shown in FIG. 14, the insertion groove 135 has a stepped portion. When the front side fixing 142 of the rod 141 of the second cylinder 140 is inserted, the punch body 134 As shown in Fig.

As a result, when the rod 141 of the second cylinder 140 is retracted, the punch body 134 is closely attached to the punch fastening means 120 tightly. 11 to 14, a punch seating groove 121 in which the flange 133 at the rear end of the body 134 of the punching means 60 is inserted is seated on the front surface of the punch fixing means 120 And is integrally formed.

16, when the second cylinder 140 is retracted, the fastener 142 integrally formed with the rod 141 is inserted into the fastener insertion groove 135 provided in the punch body 134, The flange 133 of the punch body 134 is pinched by the punch fastening means 120 in a state in which the seating groove 121 of the punch fastening means 120 is seated, And the state is maintained.

As a result, the punch means 60 of the present invention is arranged such that when the rod fixing member 142 of the second cylinder 140 is fitted and the second cylinder 140 is retracted, the inner surface of the seating groove portion 121 of the punch fixing means 120 The head 138 of the punch means 60 is inserted into the tube 6 provided in the mold and the pressurized fluid supplied through the inlet of the head 138 Pressure is applied to the tube 6 between the machined grooves of the mold to perform hot air pressure forming processing.

12 to 13, the punch centering means 130 provided in the punch device 100 of the present invention is provided with the side surfaces of the punch seating grooves 121 of the punch fastening means 120 Thereby providing the guide pieces 132 associated with the elastic body 131 provided at regular intervals. The punch fixture 142 provided on the rod 141 of the second cylinder 140 is inserted into the fixture insertion slot 135 of the punch body 134 and is inserted into the punch fixation groove portion 135 of the punch fixture 120, When the rear end flange 133 of the punch body 134 is inserted into the guide groove 121, the guide pieces 132 are pushed when the corner portion of the punch flange 133 is inserted due to the elastic force of the spring, which is the elastic body 131 The guide pieces 132 are pressed by the spring elastic force uniformly in the circumferential direction of the punch flanges 133 so that the punch body 134 integrally with the punch flange 133 is assembled The centering is always kept constant.

12, a plurality of punch centering means 130 are arranged at predetermined intervals in the circumferential direction along the corners of the seating groove portion 121 of the punch fixing means 120. In this case, A plurality of elastic members 131 of the punch centering means 130 are disposed inside the holes 122 (grooves) formed in the corner surfaces of the seating grooves 121 of the punch fastening means 120, The curved guide pieces 132 may be connected to the elastic body 131 and fixed thereto.

11 and 14, a fixing plate having holes 122 through which the punching means 60 passes is assembled to the front of the seating groove 121 of the punch fixing means 120. At this time, The rear end flange 133 of the punch means 60 is pressed and fixed.

FIG. 15 is a cross-sectional view of a steel plate and a mold according to an embodiment of the present invention, and FIG. 16 is a cross-sectional view of a heterogeneous steel plate and a mold according to an embodiment of the present invention, Sectional view of a steel plate and a mold.

15, each of the expanded portions 6a, 6b, and 6c of the tube 6 matched to the respective expanded portions is matched to a portion except for the expanded portion, Is larger than the thickness of the tube body (6).

Therefore, the thickened thickness can be formed to the same thickness as the unexpanded portion even if the outer surface of 6a, 6b, 6c is extended to the inner surfaces of the expanded portions a, b, and c.

The thickness of the tube 6 of 6a, 6b, 6c shown in Fig. 15 can be calculated in the course of the product design S1 to the thickness design S3 of the plate-like raw material shown in Fig.

6a, 6b, and 6c are calculated by considering the linearity and thickness reduction rate of the product and the weight reduction ratio. Considering the directional expansion direction vectors in the actual expansion process, 6a, 6b , 6c needs to be changed.

Referring to FIG. 16, directions of vectors expanded in accordance with their relative positions also differ in the inside of the expanded portions a and b.

That is, T2 and T4 are expanded in the vertical direction from the outer peripheral surface 6o1 of the tube 6, and T1 and T3 are angled with the outer peripheral surface 6o1 in the expanding direction. In particular, as compared with T2 and T4, T3 and T1 are finally brought into contact with the edges of the expansion parts a and b during the expansion process, thereby completing the expansion process.

In the expansion process, as the body 6 is fitted to the metal mold, the pressure is applied to the inside of the tube body 6, at which time the pressure can not change the thickness of the tube body 6 at a specific portion.

Therefore, the portion where the length is relatively extended such as T1 and T3 is likely to be thinner than the portion where the length is not longer, such as T2 and T4. Therefore, Or by making the thickness at T3 and T4 flat, it is possible to correct the difference in the microcolumn tube ratio due to the difference in the direction of the expansion vector in the actual expansion process, thereby minimizing the thickness variation after molding .

17 is a cross-sectional view of a hot air pressure forming process using a local expansion and local heating method according to an embodiment of the present invention.

17, the cartridges 53-1 and 53-2 formed on the upper mold 51 and the lower mold 52 respectively are disposed while avoiding the expansion parts (a, b, c).

As described above, when the high-pressure fluid injected into the tubular body 6 is injected in the hot-forming step, the portion of the tubular body 6 matched to the expanded tubular portions (a, b, c) is enlarged. At this time, So that the entire thickness of the tubular body 6 is uniform even after the thickness is reduced as the tube is expanded.

At this time, if the cartridges 53-1 and 53-2, which are the heating means, are disposed at the unexpanded positions excluding the expanded portions (a, b, and c), the tubes 6, A part of the tubular body 6 can be introduced from the corresponding portion into the expanded portion (a), (b), and (c) by locally increasing the ductility of the corresponding portion. , Ⓑ, ⓒ), the tubular body may protrude.

In addition, the corner portion such as 6d1 is a boundary between the expanded portion and the unexpanded portion, and the lateral pressure due to the pressure applied to T1 and T2 in Fig. 16 is concentrated, so that the thickness can be relatively thin after completion of the molding.

Therefore, by locally heating the unexpanded portion, it is possible to solve the phenomenon that the pressure is concentrated at a specific portion such as 6d1, thereby causing the thickness deviation.

Fig. 18 is a side cross-sectional view of the tube 6 in which the mounting groove C capable of mounting the vehicle body fixing means D is formed.

The vehicle body fixing means D is a device for fixing the rear crossmember for a vehicle completed with the hot air pressure molding method to the vehicle body.

It is possible to form the fastening hole E directly through the tubular body 6 without providing the vehicle body fixing means but a screw thread is formed on the inner surface of the fastening hole E to use a bolt penetrating the inside and the outside of the tubular body 6 There is a problem in that it is impossible to assemble in the tubular body 6 and there is a problem that the entire rear cross member needs to be replaced when the fastening function due to corrosion or expansion to the fastening hole E is weakened due to use of the product.

If the process of welding and assembling the single parts 10a, 10b, 20a, and 20b is used as shown in FIG. 1B, a separate process using a press method or the like is performed to form the mounting groove C shown in FIG. Should be added.

However, when the hot air pressure molding method according to the present invention is used, a plurality of mounting grooves C formed in the tube 6 can be formed at the same time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the invention disclosed herein has been presented to enable any person skilled in the art to make and use the present invention. While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. For example, those skilled in the art can utilize each of the configurations described in the above-described embodiments in a combination of them. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention. The present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In addition, claims that do not have an explicit citation in the claims may be combined to form an embodiment or be included in a new claim by amendment after the filing.

1: Raw materials
2: Single item
3: Box type parts
4:
5: overlap
6: Tubular body
10: roll forming device
11: Unclear
12: Straightener
13: Brake press
14: roll forming unit
15: Laser welding machine
16: laser oscillator
20: Preforming device
21: Lower mold
22: Upper mold
23: Sealing punch
24: sealing face
25: Fluid inlet
40:
50: Hot air pressure forming device
51: HYPERLY
52: Lower mold
53: Cartridge
60: punch means
61: Pressurized fluid inlet pipe
62: Pressurized fluid supply pipe
63: fluid discharge pipe
64: Inflow control valve
65: Discharge regulating valve
66: quenching tube
67: Cooling control valve
100: punch device
101: Support
110: first cylinder
111: first cylinder rod
112: seat groove
113: Fixed body
120: Fixing means
121: punch seating groove
122: hole
130: centering means
131: elastomer
132: guide
133: rear flange
134: punch body
135: Fixing portion insertion groove
138: punch head
140: second cylinder
141: second cylinder rod
142: Fixture

Claims (5)

A method for manufacturing a rear cross member for a vehicle,
An enlargement designing step of generating enlargement information for each part of the product including linearity, thickness reduction rate, weight reduction, and welding area and thickness information for each part of the product, which is calculated in consideration of the welding area;
Fabricating a flat plate-like material having a different thickness based on the expanded information and fabricated by a tailor welded blank (TWB) method;
Molding the raw material into a roll form by a roll forming process;
A step of producing a tube by welding and cutting a raw material molded in a roll shape by high frequency welding;
Preforming the tubular body through a preforming device;
Heating the preformed tube;
And performing the hot air pressure forming process on the tubular body by a hot air pressure forming apparatus to manufacture a rear cross member for a vehicle,
The step of manufacturing the rear crossmember for a vehicle,
Installing the tubular body into a mold;
Providing a punch device at each end of the tubular body to seal the tubular body;
Injecting a fluid into the tubular body through a pressurized fluid inlet pipe provided in the punching apparatus and pressurizing the pressurized fluid; And
And cooling the cooling medium by injecting the cooling medium into the tube through a quenching tube provided in the punching device,
Wherein the preforming comprises:
Mounting a tube end portion of the tubular body longer than the length of the mold so as to protrude from the lower mold;
Gradually pushing the sealing punch to the tube end of the tube while injecting the pressurized fluid into the tube through the inside of the sealing punch to load a predetermined pressing force;
Filling the tubular body with a pressurized fluid to a predetermined internal pressure, lowering the upper mold and fastening the mold while the internal pressure and the pressing force are applied; And
And increasing the internal pressure in the tubular body,
The step of manufacturing the rear crossmember for a vehicle,
The mold having a heating means capable of locally heating the tube,
By using the mold having the heating means,
Wherein a heating region using the heating means is varied in accordance with an expanded region of the tubular body, and a method for manufacturing a rear cross member for a vehicle using a different thickness aluminum plate. The method according to claim 1,
The thickness of the flat plate-
After molding in the step of manufacturing the rear crossmember for a vehicle,
The rear cross member for a vehicle,
Wherein the thickness of the heterogeneous plate-like raw material is varied based on the expansion ratio, and a method for manufacturing a rear cross member for a vehicle using the aluminum plate having a different thickness. delete The method according to claim 1,
The temperature of the portion where the tube expansion rate of the tube is low,
Wherein the heating is performed at a temperature higher than a temperature of a portion having a high ductility rate of the tubular body, and a method for manufacturing a rear cross member for a vehicle using a dual thickness aluminum plate. The method according to claim 1,
Wherein the tubular body has mounting grooves which are recessed into the inside of the tubular body on both sides thereof,
And a body fixing member having a U-shaped shape, both end portions of which are fitted into the mounting groove, and a fastening hole is formed on one side,
Wherein the body fixing part is mounted on the tube body and the fastening hole is screwed to a specific position of a body to which the tube body is mounted, characterized in that the method comprises a roll forming, a preforming and a hot air pressure molding fusion method, A method for manufacturing a rear cross member.

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