Method for manufacturing tubular beam structure for vehicle by using hot metal gas forming and tubular beam structure

Abstract

A method for manufacturing a tubular beam structure for a vehicle by using hot metal gas forming and a tubular beam structure, the manufacturing method comprising: according to a designed tube wall and the sectional shape of a tube, performing hot gas expansion process manufacturing to form a first tube blank (1) and a second tube blank (2) to be connected to one another; forming a process notch on a peripheral surface of the end of the first tube blank (1) that is connected to the second tube blank (2), and forming a mortise-and-tenon form of connection between the two tube blanks; and welding an outer surface at the connection point between the first tube blank (1) and the second tube blank (2), and grinding an outer surface and a welding area of a tubular beam structure to obtain a final tubular beam structure product.

Description

A manufacturing method of a hot air bulging tubular beam structure for a vehicle and a tubular beam structure Technical Field

[0001] The present invention belongs to the technical field of machining and manufacturing vehicle body structural parts, and in particular relates to a manufacturing method of a hot air bulging formed tubular beam structure for a vehicle and the tubular beam structure. Background Art

[0002] Currently, the design of vehicle body structures often uses a combination of pipes of varying thicknesses and weights to construct the main frame. For example, thicker pipes are used in locations such as the A-pillar, B-pillar, C-pillar, and door anti-collision beam to ensure strength, while thinner pipes are used in other locations to meet lightweight requirements. Currently, the connection of different pipes is primarily achieved through welding, which has disadvantages such as difficulty in preventing weld defects, susceptibility to breakage, and poor long-term reliability. Certain existing technologies, such as CN115151476B, employ a method of first processing the ends of two contacting pipe blanks into joints of different diameters before welding. Preheating the pipe blanks before blow molding is also used to improve their crystalline microstructure. This can, to a certain extent, avoid the poor reliability defects of direct welding and produce a finished product with relatively consistent overall strength. However, due to the different wall thicknesses of the matching pipe end joints in this method, the pipe deformation rates will inevitably vary during heat blow molding or subsequent use, which can result in poor fit and enlarged welds, thereby limiting the quality and performance of vehicle body structure products.

[0003] Summary of the Invention

[0004] In view of this, and in response to the technical problems existing in this field, the present invention provides a method for manufacturing a tubular beam structure for automobiles by hot air bulging, which specifically comprises the following steps:

[0005] Step 1: forming a first tube blank and a second tube blank to be connected to each other by performing a hot air expansion process according to the designed tube wall and tube cross-sectional shape; the first tube blank and the second tube blank have the same wall thickness;

[0006] Step 2: A process notch is formed on the circumferential surface of the end portion of the first tube blank for connection with the second tube blank, so as to facilitate insertion of the first tube blank when connecting with the second tube blank;

[0007] Step 3: Connect the process notch end of the first tube blank to the end of the second tube blank so that the inner surface of the process notch end of the first tube blank fits into the outer surface of the end of the second tube blank, forming a mortise and tenon joint between the two tube blanks;

[0008] The outer surfaces of the connection between the first tube blank and the second tube blank are welded to obtain a tightly connected tube beam structure. The welding position is only located at the side edges of the process notch perpendicular to the end edge of the first tube blank, and does not include the bottom edge of the process notch parallel to the end edge of the first tube blank. The corner between the side edges and the bottom edge can be welded as needed.

[0009] Step 4: Grind the outer surface and welding area of ​​the tubular beam structure to obtain the final tubular beam structure product.

[0010] Furthermore, in step three, MAG welding or laser welding is performed on the outer surfaces of the connection between the first tube blank and the second tube blank to achieve tight connection.

[0011] Furthermore, in step 1, two first tube blanks and one second tube blank are obtained by hot expansion process, and both ends of the second tube blank are respectively used to be connected to the process notch end of one of the first tube blanks.

[0012] Furthermore, in step one, a second tube blank is inserted into the outer wall of the middle portion of the tube blank between the process notch ends of the two first tube blanks through a hot air expansion process to form a raised step, so that when the second tube blank is connected to the first tube blank, both sides of the step are respectively abutted against the edge of the process notch end of a first tube blank.

[0013] Furthermore, in step one, the step is formed into a tube cross-sectional shape, inner diameter and outer diameter identical to those of the first tube blank through a hot air expansion process.

[0014] Correspondingly, the present invention also provides a hot-air-bulged tubular beam structure for vehicles, which is manufactured by executing the aforementioned method.

[0015] The manufacturing method and the tubular beam structure for hot-air-expanded automobiles provided by the present invention utilize the designed tube-end mortise and tenon connection structure in combination with the hot-air-expanding process to obtain a tubular beam product with good structural strength while meeting lightweight indicators. It is widely applicable to the manufacture of vehicle body structural parts containing tubes of different diameters, wall thicknesses, and materials. In the manufacturing process of this method, the method of first hot-expanding and then welding is selected. Compared with the background technology and the existing technology of the same type, it can avoid the phenomenon of missing welds and leaks caused by the first welding, which will lead to air leakage in the subsequent expansion process, thereby effectively improving the yield rate. The designed mortise and tenon connection with process notches can make the assembly and welding links easier to operate without reducing the firmness of the connection, which helps to significantly improve the efficiency of large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a cross-sectional view of the overall assembly structure of the tubular beam structure provided by the present invention;

[0017] FIG2 is a cross-sectional view of the tubular beam structure provided by the present invention;

[0018] FIG3 is a perspective schematic diagram of the notch end and welding position of the first tube blank process;

[0019] FIG4 is a cross-sectional view of an optional structure of a second tube blank and the connection of the first tube blanks at both ends thereof;

[0020] FIG5 is a cross-sectional view of an optional structure of a second tube blank having a step and a connection between the first tube blanks at both ends thereof;

[0021] FIG6 is an exploded view of an optional structure of a second tube blank formed with a step and a first tube blank;

[0022] FIG7 is a three-dimensional view of the welding position of the second tube blank having an optional structure with steps and the first tube blank. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0026] The present invention provides a method for manufacturing a tubular beam structure for a vehicle by hot air bulging, which specifically comprises the following steps:

[0027] The method for manufacturing a tubular beam structure for automobiles by hot air bulging specifically comprises the following steps:

[0028] Step 1: According to the designed tube wall and tube cross-sectional shape, a first tube blank and a second tube blank to be connected are formed by performing a hot air expansion process. The first tube blank and the second tube blank have the same wall thickness. The purpose of this design is to ensure that the overall shape of the connected tube beam parts is consistent. Even if thinner tube sections are used, sufficient structural strength can still be guaranteed. Even in the event of long-term use and collision, there is a similar deformation rate, thereby avoiding the risk of local fracture and contributing to the overall weight reduction of the vehicle body.

[0029] Step 2: A process notch is opened on the circumferential surface of the end of the first tube blank for connecting with the second tube blank, so as to facilitate its insertion when connecting with the second tube blank; in the actual production process, the plug-in method of the pipe without the process notch is replaced by the splicing method, which is simpler to operate and conducive to improving production efficiency.

[0030] Step 3: Connect the process notch end of the first tube blank to the end of the second tube blank so that the inner surface of the process notch end of the first tube blank fits into the outer surface of the end of the second tube blank, forming a mortise and tenon joint between the two tube blanks;

[0031] The outer surfaces of the connection between the first and second tube blanks are welded to obtain a tightly connected tube beam structure. The welding locations are located only at the end edge of the first tube blank and the side edge of the process notch perpendicular to the end edge of the first tube blank, and do not include the bottom edge of the process notch parallel to the end edge of the first tube blank. The corners between the side edge and the bottom edge can be welded as needed. Welding at the above-mentioned locations is sufficient to ensure the firmness of the connection between the different tube blanks while simplifying the welding operation. Even if a gap exists at the bottom edge of the process notch due to the lack of welding, it will not reduce the structural strength of the finished tube beam.

[0032] Step 4: Grind the outer surface and welding area of ​​the tubular beam structure to obtain the final tubular beam structure product.

[0033] Figure 1 shows a cross-sectional view of the connected tube blanks obtained by the above method. First tube blank 1 and tube blank 2 can be the same tube blank, or tube blank 2 can be a different tube blank with a different cross-section, inner and outer diameter, or wall thickness than the first tube blank. Second tube blank 3 is connected and fixed to the first tube blank or the other tube blank. When the first and second tube blanks are connected, the cross-section at the connection is shown in Figure 2. It can be seen that the inner wall of the process notch of the first tube blank 1 partially covers the outer wall of the second tube blank. Figure 3 illustrates the shape of the process notch of the first tube blank and the dark-colored weld locations. It can be seen that welding is not required at the bottom edge and corners of the process notch, simplifying the welding process and improving production efficiency.

[0034] In a preferred embodiment of the present invention, in step three, MAG welding or laser welding is performed on the outer surfaces of the connection between the first tube blank and the second tube blank to achieve tight connection.

[0035] In a preferred embodiment of the present invention, in step 1, two first tube blanks and one second tube blank are obtained by hot expansion process, and both ends of the second tube blank are respectively used to connect with the process notch end of one of the first tube blanks.

[0036] Figure 4 shows a cross-sectional view of an alternative structure using a thinner and uniformly length second tube blank 3 connected to the first tube blanks at both ends. In a preferred embodiment of the present invention, a second tube blank can be inserted into the central outer wall of the tube blank between the process notches of the two first tube blanks through a hot air expansion process to form a raised step. When the second tube blank is connected to the first tube blank, both sides of the step abut against the edges of the process notches of one of the first tube blanks. Figure 5 shows a cross-sectional view of this stepped second tube blank connected to the first tube blanks at both ends. Figure 6 shows an exploded perspective view of the connection between the three. Figure 7 illustrates the welding positions in this embodiment.

[0037] In a preferred embodiment of the present invention, the step can be formed into a tube with the same cross-sectional shape, inner diameter and outer diameter as the first tube blank through a hot expansion process.

[0038] Correspondingly, the present invention also provides a hot-air-bulged tubular beam structure for vehicles, which is manufactured by executing the aforementioned method.

[0039] It should be understood that the size of the serial numbers of the steps in the embodiment of the present invention does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0040] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a hot-air bulging tubular beam structure for a vehicle, characterized in that: The specific steps include: Step 1: According to the designed tube wall and tube cross-section shape, a first tube blank and a second tube blank to be connected to each other are formed by performing a hot air expansion process respectively; the first tube blank and the second tube blank have the same wall thickness; Step 2: a process notch is formed on the circumferential surface of the end of the first tube blank for connecting with the second tube blank, so as to facilitate insertion of the first tube blank when connecting with the second tube blank; Step 3: Connect the process notch end of the first tube blank to the end of the second tube blank, so that the inner surface of the process notch end of the first tube blank fits with the outer surface of the end of the second tube blank, and a mortise and tenon connection is formed between the two tube blanks; The outer surfaces of the connection between the first tube blank and the second tube blank are welded to obtain a tightly connected tube beam structure as a whole; the welding position is only located at the end edge of the first tube blank and the side edge of the process notch perpendicular to the end edge of the first tube blank, and does not include the bottom edge of the process notch parallel to the end edge of the first tube blank; the corner between the side edge and the bottom edge can be welded or not according to the needs; Step 4: Grind the outer surface and welding area of ​​the tube beam structure to obtain the final tube beam structure product.

2. The method according to claim 1, characterized in that: In step three, MAG welding or laser welding is performed on the outer surfaces of the connection between the first tube blank and the second tube blank to achieve tight connection.

3. The method according to claim 1, characterized in that: In step 1, two first tube blanks and one second tube blank are obtained by hot air expansion process, and two ends of the second tube blank are respectively used to be connected to the process notch end of one of the first tube blanks.

4. The method according to claim 3, characterized in that: In step one, the second tube blank is inserted into the middle outer wall of the tube blank between the process notch ends of the two first tube blanks through a hot air expansion process to form a raised step, so that when the second tube blank is connected to the first tube blank, the two sides of the step are respectively abutted against the edge of the process notch end of a first tube blank.

5. The method according to claim 3, characterized in that: In step one, the step is formed into a tube cross-sectional shape, inner diameter and outer diameter that are the same as those of the first tube blank through a hot air expansion process.

6. A hot air bulging formed tubular beam structure for automobile, characterized in that: The method is manufactured by performing the method according to any one of claims 1 to 5.

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