A method of manufacturing a hot gas expandable pipe beam structure for a vehicle and a pipe beam structure

Abstract

The application provides a manufacturing method and a pipe beam structure of a hot gas expansion forming for vehicles. The pipe end mortise and tenon connection structure is designed and combined with a hot gas expansion process, so that a pipe beam product with good structural strength can be obtained, and a lightweight index can be met at the same time. The manufacturing method is widely applicable to manufacturing of vehicle body structure parts containing pipe materials with different pipe diameters, wall thicknesses and materials. The mortise and tenon connection form with a process gap is designed, so that the assembly and welding links are more easily operated without reducing the connection firmness, and thus the efficiency of large-scale production is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of automotive body structure parts processing and manufacturing technology, specifically relating to a method for manufacturing a tubular beam structure using hot air expansion forming for automotive applications, and the tubular beam structure itself. Background Technology

[0002] Currently, in vehicle body structure design, a combination of tubing of different thicknesses and weights is often used to construct the main frame. Thicker tubing is used for A-pillars, B-pillars, C-pillars, and door anti-collision beams to ensure strength, while thinner tubing is used in other areas to meet lightweight requirements. At present, the connection of different tubing materials is mainly achieved through welding, which has drawbacks such as difficulty in preventing incomplete welds, easy breakage, and poor long-term reliability. Some existing technologies, such as CN115151476B, employ a method of first processing the ends of two contacting tube blanks into tenons and mortises of different diameters before welding. Preheating before blow molding is also used to improve the crystalline microstructure of the tube blanks, which can, to some extent, avoid the poor reliability of direct welding and obtain a finished product with relatively consistent overall strength. However, because the wall thickness of the tenon and mortise parts of the mating tube ends differs in this method, the deformation rate of the tubing will inevitably differ during blow molding or subsequent use, potentially causing poor fit and weld widening, thus limiting the quality and performance of the vehicle body structure product. Summary of the Invention

[0003] In view of the above, and to address the technical problems existing in this field, the present invention provides a method for manufacturing a tubular beam structure for automotive hot-expansion forming, specifically including the following steps:

[0004] Step 1: According to the designed pipe wall and cross-sectional shape, the first and second pipe blanks to be connected are formed by performing a hot gas expansion process; the first and second pipe blanks have the same wall thickness.

[0005] Step 2: A process notch is made on the circumferential surface of the end of the first tube blank that is used to connect with the second tube blank, so as to facilitate its insertion when connecting with the second tube blank;

[0006] 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 against the outer surface of the end of the second tube blank, forming a tenon-and-mortise connection between the two tube blanks;

[0007] Welding is performed on the outer surfaces of the connection between the first and second tube blanks to obtain a tightly connected tube beam structure. The welding position is only located on 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. Welding can be selected at the corner between the side edge and the bottom edge as needed.

[0008] Step 4: Grind the outer surface and welding area of ​​the tube beam structure to obtain the final tube beam structure.

[0009] Furthermore, in step three, MAG welding or laser welding is specifically performed on the outer surface of the connection between the first and second tube blanks to achieve a tight bond.

[0010] Furthermore, in step one, two first tube blanks and one second tube blank are obtained through a hot air expansion process. The two ends of the second tube blank are respectively used to connect to the process notch end of one of the first tube blanks.

[0011] Furthermore, 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 by a hot air expansion process to form a raised step, which is used to abut the two sides of the step against the edge of the process notch end of the first tube blank when the second tube blank is connected to the first tube blank.

[0012] Furthermore, in step one, the step is formed with the same cross-sectional shape, inner diameter, and outer diameter as the first tube blank through a hot air expansion process.

[0013] Accordingly, the present invention also provides a vehicle-mounted thermoformed tubular beam structure, which is manufactured by performing the aforementioned method.

[0014] The above-described method for manufacturing a vehicle-mounted tubular beam structure using thermoforming and the tubular beam structure provided by this invention utilizes a designed mortise and tenon joint connection structure at the pipe ends combined with a thermoforming process to obtain a tubular beam product with good structural strength while simultaneously meeting lightweight requirements. This method is widely applicable to the manufacturing of vehicle body structural components containing tubing of varying diameters, wall thicknesses, and materials. The method employs a process of thermoforming followed by welding, which, compared to prior art and similar technologies, avoids incomplete welds caused by initial welding that can lead to air leakage during subsequent expansion, thus effectively improving the yield rate. The designed mortise and tenon joint with process notches facilitates assembly and welding without compromising connection strength, significantly improving the efficiency of large-scale production. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the overall assembly structure of the tube beam structure provided by the present invention;

[0016] Figure 2 This is a cross-sectional view of the tube beam structure provided by the present invention;

[0017] Figure 3 A three-dimensional schematic diagram of the notched end and welding position of the first tube blank;

[0018] Figure 4 A cross-sectional view showing the optional structure of the second tube blank and the connection between the first tube blanks at both ends;

[0019] Figure 5 A cross-sectional view showing the optional structure for forming a stepped second tube blank and the connection of the first tube blanks at both ends;

[0020] Figure 6 An exploded view of the optional structure for forming a stepped second tube blank compared to the first tube blank;

[0021] Figure 7 A perspective view of the welding position between the optional structure for forming a stepped second tube blank and the first tube blank. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the 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.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The method for manufacturing a vehicle-mounted hot-expansion tubular beam structure provided by this invention specifically includes the following steps:

[0026] The manufacturing method of automotive hot-puffed tubular beam structures specifically includes the following steps:

[0027] Step 1: According to the designed pipe wall and cross-sectional shape, the first and second pipe blanks to be connected are formed by performing a hot air expansion process. The first and second pipe blanks have the same wall thickness. The purpose of this design is to ensure that the overall shape of the connected pipe beam parts is consistent, so that even if a thinner pipe section is used, sufficient structural strength can still be guaranteed, and similar deformation rates can be achieved during long-term use and collisions, thereby avoiding the risk of local fracture and also helping to reduce the overall weight of the vehicle body.

[0028] Step 2: A process notch is made on the circumferential surface of the end of the first tube blank that is used to connect with the second tube blank, so as to facilitate its insertion when connecting with the second tube blank; in the actual production process, the tube insertion method without the process notch is replaced with the splicing method, which is simpler to operate and helps to improve production efficiency.

[0029] 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 against the outer surface of the end of the second tube blank, forming a tenon-and-mortise connection between the two tube blanks;

[0030] Welding is performed on the outer surfaces of the connection between the first and second tube blanks to obtain a tightly connected tube-beam structure. The welding positions are 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, excluding the bottom edge of the process notch parallel to the end edge of the first tube blank. Welding at the corners between the side and bottom edges can be selected as needed. Welding at these locations is sufficient to ensure the strong 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 lack of welding, it will not reduce the structural strength of the finished tube-beam structure.

[0031] Step 4: Grind the outer surface and welding area of ​​the tube beam structure to obtain the final tube beam structure.

[0032] The cross-sectional views of the connected tube blanks obtained by the above method are as follows: Figure 1 As shown, the first tube blank 1 and tube blank 2 can be the same first tube blank, or tube blank 2 can be another tube blank with a different cross-section, inner and outer diameter, or wall thickness than the first tube blank. The second tube blank 3 is connected and fixed to the first tube blank or other tube blanks. When the first tube blank and the second tube blank are connected, the cross-section at the connection point is as shown. Figure 2 As shown, the inner wall of the process notch end of the first tube blank 1 can be seen to partially cover the outer wall of the second tube blank. Figure 3 The image shows the shape of the process notch in the first tube blank and the dark welding position. It can be seen that welding operations can be omitted at the bottom edge and corner of the process notch, which also helps to simplify the welding process and improve production efficiency.

[0033] In a preferred embodiment of the present invention, in step three, MAG welding or laser welding is specifically performed on the outer surface of the connection between the first tube blank and the second tube blank to achieve a tight connection.

[0034] In a preferred embodiment of the present invention, in step one, two first tube blanks and one second tube blank are obtained by a hot air expansion process, and the two ends of the second tube blank are respectively used to connect to the process notch end of one of the first tube blanks.

[0035] Figure 4 The diagram shows a cross-sectional view of a second tube blank 3 with a thinner and uniform length, connected to two first tube blanks at both ends. In a preferred embodiment of the invention, a hot air expansion process can be used to insert the second tube blank into the outer wall of the middle portion of the tube blank between the process notch ends of the two first tube blanks, forming a raised step. This step, when connected to the first tube blanks, abuts against the edges of the process notch ends of the first tube blanks on both sides. Figure 5 A cross-sectional view is shown showing the connection between the second tube blank with a step and the first tube blanks at both ends. Figure 6 An exploded 3D diagram showing the connection relationship between the three elements is provided. Figure 7 The welding position in this embodiment is shown in the middle.

[0036] Furthermore, in a preferred embodiment of the present invention, the step can be formed with the same tube cross-sectional shape, inner diameter, and outer diameter as the first tube blank through a hot air expansion process.

[0037] Accordingly, the present invention also provides a vehicle-mounted thermoformed tubular beam structure, which is manufactured by performing the aforementioned method.

[0038] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply 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 embodiments of the present invention.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a tubular beam structure for automotive applications using hot air expansion molding, characterized in that: Specifically, the following steps are included: Step 1: According to the designed pipe wall and cross-sectional shape, the first and second pipe blanks to be connected to each other are formed by performing a hot gas expansion process; the first and second pipe blanks have the same wall thickness. Step 2: A process notch is made on the end circumferential surface of the first tube blank that is used to connect with the second tube blank, so as to facilitate its insertion by replacing the plug-in method with the splicing method 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 against the outer surface of the end of the second tube blank, forming a tenon-and-mortise connection between the two tube blanks; Welding is performed on the outer surfaces of the connection between the first and second tube blanks to obtain a tightly connected tube-beam structure. The welding positions are 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 do not include the bottom edge of the process notch parallel to the end edge of the first tube blank. Welding can be selected at the corner between the side edge and the bottom edge as needed. Welding at the above positions ensures the firmness of the connection between different tube blanks while simplifying the welding operation. Step 4: Grind the outer surface and welding area of ​​the tube beam structure to obtain the final tube beam structure.

2. The method as described in claim 1, characterized in that: In step three, MAG welding or laser welding is specifically performed on the outer surface of the connection between the first and second tube blanks to achieve a tight bond.

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

4. The method as described in claim 3, characterized in that: In step one, a hot air expansion process is used to insert the second tube blank into the middle outer wall of the tube blank between the process notch ends of the two first tube blanks to form a raised step. When the second tube blank is connected to the first tube blank, the two sides of the step abut against the edge of the process notch end of the first tube blank.

5. The method as described in claim 4, characterized in that: In step one, the hot air expansion process is used to form the same tube cross-sectional shape, inner diameter and outer diameter as the first tube blank at the step.

6. A tubular beam structure formed by thermoforming for automotive applications, characterized in that: It is manufactured by performing the method as described in any one of claims 1-5.

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