A method and structure for manufacturing a bus body frame by integrally forming a hot gas expansion and die casting

Abstract

The application provides a hot gas expansion and die casting integrated forming method and structure of a bus body framework, and realizes integrated forming of a steel-aluminum mixed structure of several main components, such as an A column, a top edge beam, a B column and a top cover cross beam in the bus body, by combining hot gas expansion forming and a die casting process. In the manufacturing process, the hot gas expansion forming guarantees the strength of key bearing positions, and the aluminum alloy material greatly reduces the weight of positions with slightly lower strength requirements and the whole framework, thereby realizing double improvement of safety performance and lightweight indexes. Meanwhile, the hot gas expansion forming has obvious advantages in the number of parts, mold tooling and labor cost investment compared with a traditional sheet stamping mode, simplifies a component connection process and improves production efficiency and reliability of a final bus body framework product.

Description

Technical Field

[0001] This invention belongs to the field of automotive body parts manufacturing technology, specifically relating to a method and structure for manufacturing an upper body frame that is integrally formed by hot air expansion and die casting. Background Technology

[0002] In automotive body structure, the upper body is one of the key components determining important indicators such as overall vehicle performance, safety, and comfort. It is often designed with a basic birdcage-like structure, mainly composed of load-bearing components such as the A-pillar and roof beams, B-pillar, and roof crossbeams. Traditionally, these load-bearing components are manufactured by stamping thin sheets and then welding them. However, with increasingly stringent automotive regulations regarding rollover and collision safety, and the push for lightweighting, the disadvantages of thin-sheet stamping structures in balancing strength and lightweighting have become increasingly apparent. To meet strength and regulatory requirements, lightweighting has to be sacrificed in favor of relatively heavier materials. Furthermore, traditional thin-sheet stamping processes still suffer from drawbacks such as the large number of parts used, high production costs for molds, tooling, and connections, complex processes, and low production efficiency. Summary of the Invention

[0003] In view of this, and to address the technical problems existing in this field, the present invention provides a method for manufacturing an upper body frame integrally formed by hot gas expansion and die casting, specifically including the following steps:

[0004] Step 1: Select suitable steel plates and manufacture closed tube beams through high-frequency welding. These will serve as prefabricated steel pipe blanks for the subsequent manufacture of the left and right A-pillars, top edge beams, and left and right B-pillars.

[0005] Step 2: After heating the precast steel pipe blanks, place them in the corresponding molds to perform the hot gas expansion process. By filling the ends of the pipe blanks with gas, they expand and fit into the inner cavity of the mold to form a precise part outline shape. After quenching, cooling and post-processing in the mold, the finished products of the left and right A-pillars, top side beams and left and right B-pillars with predetermined strength are obtained respectively.

[0006] Step 3: Embed and fix the finished A-pillar, top side beam, and B-pillar tube beams obtained by hot gas expansion into an integral die-casting mold, and introduce high-pressure gas into the cavity of each finished product to support the inner wall of the tube beams and prevent the tube beams from being deformed by compression during die casting; inject liquid or semi-solid lightweight aluminum alloy into the mold, so that it combines with the steel tube beams to form the front and rear crossbeams of the top cover and the inner plates of the left and right B-pillars of aluminum alloy material, resulting in an integrated steel-aluminum hybrid upper body frame structure; remove it from the die-casting mold after the metal material has completely cooled and solidified;

[0007] Step 4: Connect the steel-aluminum hybrid upper body frame structure to the side panels and top cover using connecting fixtures.

[0008] Furthermore, in step one, steel bare plates or coated plates with a strength range of 1200-2000 MPa and a material thickness of 0.8-4.0 mm are specifically selected, and prefabricated steel pipe blanks of equal or unequal thickness are manufactured as needed.

[0009] Furthermore, in step three, the gas filling and pressure holding operation can be omitted during die casting, depending on actual needs.

[0010] Furthermore, in step three, before embedding each finished tube beam into the overall die-casting mold, the finished tube beams of the A-pillar, B-pillar and top edge beam on one side of the vehicle body are first fixed by performing two-stage welding to obtain a single-sided AB-pillar frame semi-finished product; then the two AB-pillar frame semi-finished products are respectively embedded into the corresponding left and right side cavities in the overall die-casting mold.

[0011] Furthermore, in step one, two prefabricated steel pipe blanks are manufactured for either the left or right B-pillar, and after steps two and three, a single-sided B-pillar structure is formed in which two mutually spaced steel pipe beams are embedded in the inner plate of the aluminum alloy B-pillar; the inner plate of the B-pillar also has a space for accommodating the rear door hinge mounting plate, seat belt, wiring and connecting parts.

[0012] Furthermore, the feature is that after the integrated steel-aluminum hybrid upper body frame structure is removed from the overall die-casting mold, necessary processes including protective welding, cutting, and grinding are performed.

[0013] Accordingly, the present invention also provides an upper body frame structure integrally formed by hot air expansion and die casting, which is manufactured using the above method.

[0014] The above-mentioned method and structure for manufacturing an integrated upper body frame using hot gas expansion and die casting provided by this invention achieves integrated forming of a steel-aluminum hybrid structure for several major components of the upper body, including the A-pillar, top side beam, B-pillar, and roof crossbeam, by combining hot gas expansion with die casting processes. During manufacturing, hot gas expansion ensures the strength of critical load-bearing positions, while the aluminum alloy material significantly reduces the weight of areas with lower strength requirements and the overall frame, thus achieving a dual improvement in safety performance and lightweighting. Simultaneously, hot gas expansion gives this invention significant advantages over traditional sheet metal stamping methods in terms of the number of parts, mold tooling, and labor costs, simplifying component connection processes and improving production efficiency and the reliability of the final body frame product. Attached Figure Description

[0015] Figure 1 A diagram of the upper body frame manufactured based on the present invention, which is integrally formed by hot air expansion and die casting.

[0016] Figure 2 The images show a top view and a partial cross-sectional view of the upper body frame manufactured based on the present invention.

[0017] Figure 3 An exploded view of the finished tube beams manufactured by the hot air bulging process of the present invention;

[0018] Figure 4 This is a schematic diagram showing the optional positions for performing MIG welding on the finished pipe beam in the method of the present invention;

[0019] Figure 5 This is a schematic diagram of the assembly of the upper body frame, side panels, and top cover manufactured based on the present invention.

[0020] Explanation of the attached diagrams: 1- Finished right A-pillar tube beam, 2- Finished right B-pillar tube beam a, 3- Finished right B-pillar tube beam b, 4- Finished left A-pillar tube beam, 5- Finished left B-pillar tube beam a, 6- Finished left B-pillar tube beam b, 7- Front beam of the roof, 8- Rear beam of the roof, 9- Inner panel of the right B-pillar, 10- Inner panel of the left B-pillar, 11- Right side panel, 12- Left side panel, 13- Roof, 100- Semi-finished right AB-pillar frame, 200- Semi-finished left AB-pillar frame, 300- Integrated upper body frame structure. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] The method for manufacturing an upper body frame integrally formed by hot gas expansion and die casting provided by the present invention specifically includes the following steps:

[0024] Step 1: Select suitable steel plates and manufacture closed tube beams through high-frequency welding. These will serve as prefabricated steel pipe blanks for the subsequent manufacture of the left and right A-pillars, top edge beams, and left and right B-pillars.

[0025] Step 2: After heating the precast steel pipe blanks, place them in the corresponding molds to perform the hot gas expansion process. By filling the ends of the pipe blanks with gas, they expand and fit into the inner cavity of the mold to form a precise part outline shape. After quenching, cooling and post-processing in the mold, the finished products of the left and right A-pillars, top side beams and left and right B-pillars with predetermined strength are obtained respectively.

[0026] Step 3: Embed and fix the finished A-pillar, top side beam, and B-pillar tube beam obtained by hot gas expansion into an integral die-casting mold, and introduce high-pressure gas into the cavity of each finished product to support the inner wall of the tube beam and prevent the tube beam from being deformed by compression during die casting; inject liquid or semi-solid lightweight aluminum alloy into the mold, so that it combines with the steel tube beam to form the front and rear cross beams of the top cover and the inner plates of the left and right B-pillars of aluminum alloy material, to obtain an integrated steel-aluminum hybrid upper body frame structure 300; after the metal material has completely cooled and solidified, remove it from the die-casting mold;

[0027] Step 4: Connect the steel-aluminum hybrid upper body frame structure to the left and right side panels 11 and 12 and the top cover 13 using connecting fixtures, as follows: Figure 5 As shown. The assembly method of each major component in the upper body frame structure is as follows. Figure 1 , 2 As shown, the partial cross-sections connecting the front beam 7 and the rear beam 8 of the roof to the AB pillar frame on both sides can be die-cast according to manufacturing requirements. Figure 2 The shape shown.

[0028] In a preferred embodiment of the present invention, in step one, bare steel plates or coated plates with a strength range of 1200-2000 MPa and a material thickness of 0.8-4.0 mm are specifically selected, and prefabricated steel pipe blanks of equal or unequal thickness are manufactured as needed.

[0029] In a preferred embodiment of the present invention, the gas filling and pressure holding operation in step three can be omitted as needed during die casting.

[0030] In a preferred embodiment of the present invention, such as Figure 4 As shown, in step three, before embedding each finished tube beam into the overall die-casting mold, the finished tube beam 1 of the right A-pillar, the finished tube beam of the right B-pillar, and the finished tube beam of the right top edge beam are first fixed by MIG welding at the positions circled in the figure, to obtain the semi-finished product 100 of the right AB pillar frame. The finished tube beam 4 of the left A-pillar, the finished tube beam of the left B-pillar, and the finished tube beam of the left top edge beam are also fixed by MIG welding at the positions circled in the figure, to obtain the semi-finished product 200 of the left AB pillar frame. Then, the semi-finished products 100 and 200 of the AB pillar frames on both sides are respectively embedded into the corresponding left and right side cavities in the overall die-casting mold.

[0031] In a preferred embodiment of the present invention, such as Figure 3As shown, in step one, two prefabricated steel pipe blanks are manufactured for either the left or right B-pillar. After steps two and three, a single-sided B-pillar structure is formed by embedding two mutually spaced steel pipe beams in the inner plate of the aluminum alloy B-pillar. For example, the right B-pillar structure is composed of right B-pillar pipe beam a2 and right B-pillar pipe beam b3, and the left B-pillar structure is composed of left B-pillar pipe beam a5 and right B-pillar pipe beam b6. The inner plate of the B-pillar also has a space for installing the rear door hinge mounting plate, seat belt, wiring, and connecting parts.

[0032] In a preferred embodiment of the present invention, the characteristic is that after the integrated steel-aluminum hybrid upper body frame structure is removed from the overall die-casting mold, necessary processes including protective welding, cutting, and grinding are performed.

[0033] Accordingly, the present invention also provides an upper body frame structure integrally formed by hot air expansion and die casting, which is manufactured using the above method.

[0034] 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.

[0035] 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 an upper body frame integrally formed by hot gas expansion and die casting, characterized in that: Specifically, the following steps are included: Step 1: Select suitable steel plates and manufacture closed tube beams through high-frequency welding. These will serve as prefabricated steel pipe blanks for the subsequent manufacture of the left and right A-pillars, top edge beams, and left and right B-pillars. Step 2: After heating the precast steel pipe blanks, place them in the corresponding molds to perform the hot gas expansion process. By filling the ends of the pipe blanks with gas, they expand and fit into the inner cavity of the mold to form a precise part outline shape. After quenching, cooling and post-processing in the mold, the finished products of the left and right A-pillars, top side beams and left and right B-pillars with predetermined strength are obtained respectively. Step 3: Embed and fix the finished A-pillar, top side beam, and B-pillar tube beam obtained by hot gas expansion into an integral die-casting mold, and introduce high-pressure gas into the cavity of each finished product to support the inner wall of the tube beam and prevent the tube beam from being deformed by compression during die casting; inject liquid or semi-solid lightweight aluminum alloy into the mold, so that it combines with the steel tube beam to form the front and rear cross beams of the top cover and the inner plates of the left and right B-pillars of aluminum alloy material, to obtain an integrated steel-aluminum hybrid upper body frame structure; after the metal material has completely cooled and solidified, remove it from the integral die-casting mold; Step 4: Connect the steel-aluminum hybrid upper body frame structure to the side panels and top cover using connecting fixtures.

2. The method for manufacturing the upper body frame integrally formed by hot gas expansion and die casting as described in claim 1, characterized in that: In step one, steel bare plates or coated plates with a strength range of 1200-2000 MPa and a material thickness of 0.8-4.0 mm are selected, and prefabricated steel pipe blanks of equal or unequal thickness are manufactured as needed.

3. The method for manufacturing the upper body frame integrally formed by hot gas expansion and die casting as described in claim 1, characterized in that: In step three, the gas filling and pressure holding operation can be omitted during die casting, depending on actual needs.

4. The method for manufacturing the upper body frame integrally formed by hot gas expansion and die casting as described in claim 1, characterized in that: In step three, before embedding each finished tube beam into the overall die-casting mold, the finished A-pillar, B-pillar and top edge beam tube beams on one side of the vehicle body are first fixed by performing two-stage welding to obtain a single-sided AB-pillar frame semi-finished product; then the two AB-pillar frame semi-finished products are respectively embedded into the corresponding left and right side cavities in the overall die-casting mold.

5. The method for manufacturing the upper body frame integrally formed by hot gas expansion and die casting as described in claim 1, characterized in that: In step one, two prefabricated steel pipe blanks are manufactured for either the left or right B-pillar. After steps two and three, a single-sided B-pillar structure is formed in which two mutually spaced steel pipe beams are embedded in the inner plate of the aluminum alloy B-pillar. The inner plate of the B-pillar also has a space for accommodating the rear door hinge mounting plate, seat belt, wiring, and connecting parts.

6. The method for manufacturing the upper body frame integrally formed by hot gas expansion and die casting as described in claim 1, characterized in that: After the integrated steel-aluminum hybrid upper body frame structure is removed from the overall die-casting mold, it undergoes necessary processing including protective welding, cutting, and grinding.

7. A vehicle body frame structure integrally formed by hot air expansion and die casting, characterized in that: It is manufactured using the method described in any one of claims 1-6.

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