Novel light-weight low-cost tubular beam type front auxiliary frame and manufacturing method

Abstract

The invention relates to the field of auxiliary frames, and discloses a novel light-weight low-cost tubular beam type front auxiliary frame and a manufacturing method. A rear cross beam comprises a tubular beam I and a tubular beam II, and the two ends of the beam I and the two ends of the beam II are connected with a left longitudinal beam and a right longitudinal beam; the first beam is located on the inner side, the two front foot connecting plates are located at the two ends of the first beam respectively, one end of each front foot connecting plate is welded to the first beam, and the other end of each front foot connecting plate is welded to the adjacent left longitudinal beam or right longitudinal beam; the rear swing arm support assembly is located at the left end and the right end of the first beam and the second beam and comprises an upper plate and a lower plate, and the upper plate and the lower plate wrap the connecting position of the first beam and the longitudinal beam and the connecting position of the second beam and the longitudinal beam. A lower support is arranged below the first beam and the second beam, the left end and the right end of the lower support are fixedly welded to the lower plate, and the front side and the rear side of the lower support are welded to the first beam and the second beam respectively. The auxiliary frame has the advantages of light weight, low cost, high strength and the like.

Description

Technical Field

[0001] The present invention relates to the field of subframes, and in particular to a novel lightweight, low-cost tubular beam front subframe and a manufacturing method thereof. Background Art

[0002] Traditional front subframes often utilize welded steel structures assembled from stamped parts or cast processes, resulting in significant weight, high cost, and complex manufacturing. With the development of new energy vehicles, the demand for lightweighting is growing. However, existing subframes often struggle to maintain both rigidity and durability while reducing weight. Therefore, a new lightweight, low-cost front subframe is urgently needed that can reduce weight while ensuring safety and optimize manufacturing processes. Summary of the Invention

[0003] The present invention addresses the following problems existing in the prior art: [1] The traditional stamped snap-fit ​​beam front subframe is very heavy (>20KG), which is not conducive to fuel economy and electric endurance. Although the aluminum alloy structure can reduce weight, some areas subject to high-intensity loads still need to be strengthened, which increases the design and manufacturing costs. It is currently only used in mid-to-high-end models.

[0004] [2] Existing lightweight designs (such as multi-cavity aluminum alloy structures) may lead to insufficient local stiffness due to excessive weight reduction, especially at the suspension mounting points and powertrain mounting points, which may easily cause stress concentration and affect the durability of the subframe.

[0005] [3] In traditional stamped snap-fit ​​beam subframes, every two stamped parts snapped together or every two sub-assemblies connected need to be welded continuously, resulting in a large number of welds (about 10 meters of welds). At the same time, multiple processes and about 8 sets of welding tools are required to complete the process. Welding deformation and weld quality are difficult to control, which makes the welds prone to fatigue and cracking.

[0006] [4] Traditional stamped and snap-fit ​​beam subframes require an overlap of >7mm, which increases the weight of the stamped parts. Furthermore, to ensure connection with the vehicle body, the front ends of the left and right longitudinal beams are formed into an L-shaped shape. This results in low stamped part utilization. The material utilization of traditional longitudinal beams is <50%. The material utilization of the entire stamped part of a traditional stamped and snap-fit ​​beam subframe is approximately 60%.

[0007] [5] The traditional stamped snap-fit ​​beam subframe consists of about 35 stamped parts. The stamping of these stamped parts requires a large number of molds (about 200 sets of molds) and a large number of single-product inspection tools to ensure the quality of the stamped parts, which increases R&D costs.

[0008] [6] Although integrated casting can improve rigidity and reduce weight, the mold development and manufacturing costs are high, and thick and large cross-sections are prone to casting defects such as pores and shrinkage holes.

[0009] [7] The existing subframe has poor dynamic stiffness in the X / Y / Z directions, which affects the vehicle's handling and comfort. A new lightweight, low-cost tubular beam front subframe is proposed.

[0010] In order to solve the above technical problems, the present invention is solved by the following technical solutions: A new lightweight, low-cost tubular beam front subframe, comprising a front crossbeam, a rear crossbeam, a left longitudinal beam, and a right longitudinal beam, which are connected to each other at the ends to form a "well"-shaped frame; The rear crossbeam includes tubular beams 1 and 2, both ends of which are connected to the left and right longitudinal beams. Beam 1 is located on the inner side and also includes two front foot connecting plates, one end of which is welded to beam 1 and the other end is welded to the adjacent left or right longitudinal beam. Also included is a rear swing arm bracket assembly, which is located at the left and right ends of beam one and beam two, and includes an upper plate and a lower plate, and the upper plate and the lower plate cover the connection position of beam one, beam two and the longitudinal beam inside; A lower bracket is provided below the first beam and the second beam. The left and right ends of the lower bracket are welded and fixed to the lower plate, and the front side and the rear side are welded to the first beam and the second beam respectively.

[0011] Preferably, it also includes a rear foot connecting plate, which is matched with the rear swing arm assembly, one end of the rear foot connecting plate is welded to the upper plate and the lower plate, and the other end is welded to the corresponding left longitudinal beam or right longitudinal beam.

[0012] Preferably, the rear foot connecting plate is a U-shaped plate with its U-shaped opening facing inward.

[0013] Preferably, the front foot connecting plate is a U-shaped plate with its U-shaped opening facing the rear foot connecting plate. The rear foot connecting plate and the front foot connecting plate are arranged in parallel. The front foot connecting plate is bent to form a notch on one side of the U-shaped opening. The bottom surface of the notch is a plane with a first fixing hole provided on the plane.

[0014] Preferably, the left longitudinal beam and the right longitudinal beam have the same structure and are symmetrically arranged. The front end of the left longitudinal beam has a curved portion 1 and a horizontal portion 2. The curved portion 1 is higher than the horizontal portion and an installation space is formed at the transition. A front swing bracket is welded and fixed in the installation space. The front swing bracket includes piece 1, piece 2 and piece 3. Piece 1 is welded and fixed to the curved portion 1 and the horizontal portion 2 to form a triangle. Piece 2 is clamped on the left longitudinal beam and welded and fixed. Piece 3 is connected between piece 1 and piece 2. A gap is formed between piece 3 and the left longitudinal beam. Piece 1, piece 2 and piece 3 are integrally formed.

[0015] Preferably, the front cross beam is a U-shaped beam, and both ends of the front cross beam are welded and fixed to the left longitudinal beam and the right longitudinal beam.

[0016] Preferably, a plurality of slots are provided at both ends of the plate 1 and the plate 2, and the slots correspond one-to-one to the beam 1, the beam 2 and the longitudinal beam.

[0017] Compared with the existing technology, this solution has the following beneficial effects: 1. This new lightweight, low-cost tubular beam front subframe underwent extensive CAE analysis and structural optimization, from conceptual design requirements to detailed structural design. The final system's stress strength, static stiffness, and dynamic stiffness analysis results are comparable to those of traditional upper and lower buckled beams or aluminum alloy front subframes. 2. During prototype vehicle testing, this new lightweight, low-cost tubular beam front subframe demonstrated comparable NVH performance, comfort, and handling to a conventional stamped, snap-fit ​​beam front subframe. 3. The new lightweight, low-cost tubular beam front subframe weighs approximately 15.8 kg, which is approximately 4.2 kg lighter than the traditional stamped snap-fit ​​beam front subframe, a weight reduction of approximately 20%. The longitudinal beams and rear cross beams of the new lightweight, low-cost tubular beam front subframe both adopt a tubular beam structure, with a material utilization rate of nearly 100%. In addition, the other stamped parts have simple shapes and structures, and the material utilization rate of the stamped parts also reaches approximately 75%. Therefore, the overall material utilization rate of the new lightweight, low-cost tubular beam front subframe reaches approximately 85%, which is 70% higher than the material utilization rate of the traditional stamped snap-fit ​​beam subframe. 4. This new lightweight, low-cost tubular beam front subframe adopts a tubular beam structure to reduce the use of stamping parts and the welding tooling required for the fastening and welding of stamping parts. Only about four sets of assembly welding tooling are needed. At the same time, the tubular beam subframe requires about 17 stamping parts, and the development of only about 50 stamping molds is required. Compared with the traditional stamped fastening beam subframe, the R&D investment is reduced by about 6 sets of welding tooling and about 150 sets of molds. The investment costs of fixtures and molds are reduced by 60% and 75% respectively.

[0018] 5. The weld seam of this new lightweight, low-cost tubular beam front subframe is approximately 6.3 meters, which is 4 to 6 meters shorter than the weld seam of the traditional stamped snap-fit ​​beam subframe. It also reduces welding wire loss by 40%, energy loss by 10%, and manufacturing costs by approximately 40%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the device.

[0020] Figure 2 yes Figure 1 Schematic diagram of side view.

[0021] Figure 3 yes Figure 1 Schematic diagram of the upward perspective. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0023] The figures are marked as follows: 1-front crossbeam, 2-rear crossbeam, 3-beam one, 4-beam two, 5-left longitudinal beam, 6-right longitudinal beam, 7-rear swing arm assembly, 8-upper plate, 9-lower plate, 10-lower bracket, 11-rear foot connecting plate, 12-front foot connecting plate, 13-recess, 14-first fixing hole, 15-bend, 16-horizontal portion, 17-front swing bracket, 18-piece one, 19-piece two, 20-piece three, 21-gap, 22-protrusion, 23-U-shaped fixing portion, 24-transverse reinforcement rib, 25-longitudinal reinforcement rib, 26-wiring harness bracket.

[0024] Example 1 A novel lightweight, low-cost tubular beam front subframe, comprising a front crossbeam 1, a rear crossbeam 2, a left longitudinal beam 5 and a right longitudinal beam 6, which are connected to each other at the ends to form a "well"-shaped frame; the rear crossbeam 2 comprises a tubular beam 1 3 and a beam 2 4, both ends of which are connected to the left longitudinal beam 5 and the right longitudinal beam 6; the beam 1 3 is located on the inner side and also includes a front foot connecting plate 12, the number of the front foot connecting plates 12 is two, respectively located at the two ends of the beam 1 3, and one of the front foot connecting plates 12 is connected to the left longitudinal beam 5 and the right longitudinal beam 6. The front crossbeam 1 is welded to the left and right longitudinal beams 5 and 6, respectively, at one end. The rear crossbeam 1 is also assembled, located at the left and right ends of the first and second beams 3 and 4. It comprises an upper plate 8 and a lower plate 9, which enclose the connection points between the first and second beams 3 and 4 and the longitudinal beams. A lower bracket 10 is located beneath the first and second beams 3 and 4. Its left and right ends are welded to the lower plate 9, and its front and rear ends are welded to the first and second beams 4, respectively. The front crossbeam 1 is made of high-strength steel.

[0025] The rear leg connecting plate 11 is also included and is provided in conjunction with the rear swing arm assembly 7. One end of the rear leg connecting plate 11 is welded to the upper plate 8 and the lower plate 9, and the other end is welded to the corresponding left longitudinal beam 5 or right longitudinal beam 6. The front leg connecting plate 12 and the rear leg connecting plate 11 both serve as reinforcement plates to ensure product reliability and stability. Combined with the double rear crossbeam 2 design, it further ensures the support strength of the rear crossbeam 2 installation area and reduces the overall weight.

[0026] To ensure the strength of the connecting plate and the connection areas with the longitudinal and transverse beams, the rear foot connecting plate 11 is a U-shaped plate with its U-shaped opening facing inward. The front foot connecting plate 12 is also a U-shaped plate with its U-shaped opening facing the rear foot connecting plate 11. The rear foot connecting plate 11 and the front foot connecting plate 12 are arranged parallel to each other. The front foot connecting plate 12 is bent to form a notch 13 on one side of the U-shaped opening. The bottom surface of the notch 13 is flat, and a first fixing hole 14 is defined in this flat surface. Furthermore, the first fixing hole 14 can be used to mount a workpiece as needed, or to connect a reinforcement rod to further enhance the strength of the entire subframe.

[0027] In this embodiment, the left longitudinal beam 5 and the right longitudinal beam 6 have the same structure and are symmetrically arranged. The front end of the left longitudinal beam 5 has a curved portion 15- and a horizontal portion 16-. The curved portion 15- is higher than the horizontal portion 16 and forms an installation space at the transition. A front swing bracket 17 is welded and fixed in the installation space. The front swing bracket 17 includes a first piece 18, a second piece 19, and a third piece 20. The first piece 18 is welded and fixed to the curved portion 15- and the horizontal portion 16- to form a triangle. The second piece 19 is clamped onto the left longitudinal beam 5 and welded. The third piece 20 is connected between the first piece 18 and the second piece 19. A gap 21 is formed between the third piece 20 and the left longitudinal beam 5. The first piece 18, the second piece 19, and the third piece 20 are integrally formed. The left longitudinal beam 5 and the right longitudinal beam 6 are formed by bending and punching processes to reduce welding length and part weight, while also reducing mold development.

[0028] The internal design of the left and right longitudinal beams 6 adopts a polygonal cavity, and the rear cross beam 2 adopts a circular tube structure; to improve the stiffness / weight ratio, the front cross beam 1 is a U-shaped beam, and the two ends of the front cross beam 1 are welded and fixed to the left longitudinal beam 5 and the right longitudinal beam 6.

[0029] The rear cross member 2 is made of S420MC material, the left and right longitudinal beams 6 and the swing arm bracket are made of S550MC material; the front cross member 1, the front foot connecting plate 12, the rear foot connecting plate 11 and the lower bracket 10 are made of S500M and ASPH440 materials, further reducing weight while increasing overall strength.

[0030] The upper and lower plates are provided with multiple slots at both ends, corresponding to beam 1 3, beam 2 4, and longitudinal beam 1 3. A gap 21 exists between beam 1 3 and beam 2 4. The lower bracket 10 is a long, plate-like member with an outward protrusion 22 in the middle. The ends of the lower bracket 10 are bent to form a U-shaped fixing portion 23, which is narrower than the middle area. The U-shaped fixing portion 23 is welded to the lower plate 9, and the sides of the middle area are welded to beam 1 3 and beam 2 4 on either side. The middle area is provided with transverse reinforcing ribs 24 and longitudinal reinforcing ribs 25 at intervals along its length.

[0031] This new lightweight, low-cost tubular beam front subframe has undergone a lot of CAE analysis and structural optimization from the conceptual design requirements to the specific structure design. The stress strength, static stiffness, and dynamic stiffness analysis results of the final system are no less than those of traditional upper and lower buckled beams or aluminum alloy front subframes; in the prototype test of this new lightweight, low-cost tubular beam front subframe, its NVH performance, comfort, and handling performance are also comparable to those of traditional stamped buckled beam front subframes; the overall weight of this new lightweight, low-cost tubular beam front subframe is about 15.8KG, which is about 4.2KG lighter than the traditional stamped buckled beam front subframe, a weight reduction of about 20%; the longitudinal beams and rear cross beams 2 of this new lightweight, low-cost tubular beam front subframe all adopt tubular beam structure, and the material utilization rate of the tubular beam is close to 100%, and the shape and structure of other stamping parts are simple, and the stamping parts are The material utilization rate also reaches approximately 75%, resulting in an overall material utilization rate of approximately 85% for this new lightweight, low-cost tubular beam front subframe, a 70% improvement over traditional stamped and snap-fit ​​beam subframes. The tubular beam structure of this new lightweight, low-cost tubular beam front subframe reduces the use of stamped parts and the welding tooling required for the snap-fit ​​welding of these parts, requiring only approximately four sets of assembly welding tooling. Furthermore, the tubular beam subframe requires approximately 17 stamped parts, but only requires approximately 50 sets of stamping dies. This reduces the R&D investment in approximately six welding tooling sets and approximately 150 sets of dies compared to traditional stamped and snap-fit ​​beam subframes, with fixture and die investment reduced by 60% and 75%, respectively. The weld seam of this new lightweight, low-cost tubular beam front subframe is approximately 6.3 meters, 4-6 meters shorter than that of traditional stamped and snap-fit ​​beam subframes. This reduces wire loss by 40%, energy loss by 10%, and manufacturing costs by approximately 40%.

[0032] Example 2 This embodiment discloses a method for manufacturing the subframe of embodiment 1, comprising the following steps: Step 1: Design a three-dimensional model of the product, where the left longitudinal beam 5, the right longitudinal beam 6, and the rear cross beam 2 are tubular structures, and the rear cross beam 2 is composed of two parallel beams; Step 2: Design according to the design parameter requirements, and add the front foot connecting plate 12, the rear foot connecting plate 11, and the rear swing bracket assembly to the model of step 1; Step 3: Perform CAE analysis on the model in step 2 to analyze stress areas and areas where weight can be reduced; Step 4: Optimize the structure of each part, welding position and weight reduction design so that the stress strength, static stiffness and dynamic stiffness analysis results of the model meet the requirements; Step 5: Perform welding operation; connect the left longitudinal beam 5, the right longitudinal beam 6, the cross beam 1 3, and the cross beam 2 4 to form a main frame through a two-conservation welding method; Step 6: Then, the upper plate 8 and the lower plate 9 are welded together to form the rear swing arm bracket assembly; Step 7. Place the left and right front swing arm brackets and the left and right rear swing arm bracket assemblies on the main frame beam, and then fix them together by two welding methods; Step 8: Again, place the left and right front foot connecting plates 12 and the left and right rear foot connecting plates 11 on the main frame beam and fix them by two-way welding; Step 9. Finally, place the lower bracket 10, harness bracket 26, left and right bottom guard plate brackets, left and right front bottom guard plate brackets and other body mounting sleeves on the front sub-bracket at the same time, and then connect them to the front sub-frame through two-way welding.

Claims

1. A new lightweight, low-cost tubular beam front subframe, characterized by: It comprises a front crossbeam (1), a rear crossbeam (2), a left longitudinal beam (5) and a right longitudinal beam (6), which are connected to each other at their ends to form a rectangular frame; The rear cross beam (2) includes a tubular beam 1 (3) and a beam 2 (4), both ends of which are connected to the left longitudinal beam (5) and the right longitudinal beam (6); the beam 1 (3) is located on the inner side and also includes a front foot connecting plate (12), the number of which is two and which are located at both ends of the beam 1 (3), one end of the front foot connecting plate (12) is welded to the beam 1 (3), and the other end is welded to the adjacent left longitudinal beam (5) or right longitudinal beam (6); It also includes a rear swing arm bracket assembly, which is located at the left and right ends of beam one (3) and beam two (4), and includes an upper plate (8) and a lower plate (9), and the upper plate (8) and the lower plate (9) cover the connection position between beam one (3), beam two (4) and the longitudinal beam inside; A lower bracket (10) is provided below the first beam (3) and the second beam (4). The left and right ends of the lower bracket (10) are welded and fixed to the lower plate (9), and the front side and the rear side are welded to the first beam (3) and the second beam (4) respectively.

2. The novel lightweight, low-cost tubular beam front subframe according to claim 1 is characterized by: The rear foot connecting plate (11) is also included. The rear foot connecting plate (11) is matched with the rear swing arm assembly (7). One end of the rear foot connecting plate (11) is welded to the upper plate (8) and the lower plate (9), and the other end is welded to the corresponding left longitudinal beam (5) or right longitudinal beam (6).

3. The novel lightweight, low-cost tubular beam front subframe according to claim 2 is characterized by: The rear foot connecting plate (11) is a U-shaped plate, and its U-shaped opening faces inward.

4. The novel lightweight, low-cost tubular beam front subframe according to claim 3 is characterized by: The front foot connecting plate (12) is a U-shaped plate, the U-shaped opening of which faces the rear foot connecting plate (11), the rear foot connecting plate (11) and the front foot connecting plate (12) are arranged in parallel, and the front foot connecting plate (12) is formed with a notch (13) on one side of the U-shaped opening by bending, and the bottom surface of the notch (13) is a plane, and a first fixing hole (14) is opened on the plane.

5. The novel lightweight, low-cost tubular beam front subframe according to claim 4 is characterized in that: The left longitudinal beam (5) and the right longitudinal beam (6) have the same structure and are symmetrically arranged. The front end of the left longitudinal beam (5) has a curved portion (15) 1 and a horizontal portion (16) 2. The curved portion (15) 1 is higher than the horizontal portion (16) and an installation space is formed at the transition. A front swing bracket (17) is welded and fixed in the installation space. The front swing bracket (17) includes a piece 1 (18), a piece 2 (19) and a piece 3 (20). The piece 1 (18) is welded and fixed to the curved portion (15) 1 and the horizontal portion (16) 2 to form a triangle. The piece 2 (19) is clamped on the left longitudinal beam (5) and is welded and fixed. The piece 3 (20) is connected between the piece 1 (18) and the piece 2 (19). A gap (21) is formed between the piece 3 (20) and the left longitudinal beam (5). The piece 1 (18), the piece 2 (19) and the piece 3 (20) are integrally formed.

6. The novel lightweight, low-cost tubular beam front subframe according to claim 1 is characterized by: The front cross beam (1) is a U-shaped beam, and both ends of the front cross beam (1) are welded and fixed to the left longitudinal beam (5) and the right longitudinal beam (6).

7. The novel lightweight, low-cost tubular beam front subframe according to claim 1 is characterized by: A plurality of slots are provided at both ends of the upper plate and the lower plate, and the slots correspond to beam 1 (3), beam 2 (4) and longitudinal beam 1 (3).

8. The novel lightweight, low-cost tubular beam front subframe according to claim 1 is characterized by: There is a gap (21) between the first beam (3) and the second beam (4), the lower bracket (10) is a long strip plate-like member, the middle part of the lower bracket (10) protrudes outward (22), and the two ends of the lower bracket (10) are bent to form a U-shaped fixing portion (23) with a width smaller than the middle area. The U-shaped fixing portion (23) is welded to the lower plate (9), and the two side edges of the middle area are welded to the first beam (3) and the second beam (4) on both sides. The middle area is provided with transverse reinforcing ribs (24) and longitudinal reinforcing ribs (25) at intervals along its length direction.

9. A novel method for manufacturing a lightweight, low-cost tubular beam front subframe, characterized by: The following steps are involved: Step 1: Design a three-dimensional model of the product, wherein the left longitudinal beam (5), the right longitudinal beam (6), and the rear cross beam (2) are selected to be tubular structures, and the rear cross beam (2) is selected to be composed of two parallel beams; Step 2: Design according to the design parameter requirements, and add the front foot connecting plate (12), the rear foot connecting plate (11), and the rear swing bracket assembly to the model of step 1; Step 3: Perform CAE analysis on the model in step 2 to analyze stress areas and areas where weight can be reduced; Step 4: Optimize the structure of each part, welding position and weight reduction design so that the stress strength, static stiffness and dynamic stiffness analysis results of the model meet the requirements; Step 5: Perform welding operations; connect the left longitudinal beam (5), the right longitudinal beam (6), the cross beam 1 (3), and the cross beam 2 (4) to form a main frame by a two-conservation welding method; Step 6: Then, the upper plate (8) and the lower plate (9) are welded together to form the rear swing arm bracket assembly; Step 7. Place the left and right front swing arm brackets and the left and right rear swing arm bracket assemblies on the main frame beam, and then fix them together by two welding methods; Step 8: Again, place the left and right front foot connecting plates (12) and the left and right rear foot connecting plates (11) on the main frame beam and fix them by two-way welding; Step 9: Finally, place the lower bracket (10), the harness bracket (26), the left and right bottom guard plate brackets, the left and right front bottom guard plate brackets and other body mounting sleeves on the front sub-bracket at the same time, and then connect them to the front sub-frame by two-way welding.

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