Extrusion and die-casting composite integrated aluminum alloy frame for special vehicle

Abstract

The utility model relates to an extrusion and die-casting composite integrated aluminum alloy frame for a special vehicle, which comprises two identical longitudinal beams which are arranged side by side, and a plurality of cross beams are arranged between the two longitudinal beams in parallel; the cross beam comprises a longitudinal beam front section middle cross beam, a supporting leg cross beam, a longitudinal beam rear section middle cross beam, a middle lock cross beam and a suspension cross beam, the longitudinal beam front section middle cross beam is arranged at the longitudinal beam front section and the joint of the longitudinal beam front section and the longitudinal beam middle section, and the longitudinal beam middle section and the supporting leg cross beam are arranged at the joint of the longitudinal beam middle section and the longitudinal beam rear section; the longitudinal beam rear section middle cross beam is arranged at the front section and the rear section of the longitudinal beam rear section, the middle lock cross beam is arranged between the longitudinal beam rear section middle cross beam at the front section of the longitudinal beam rear section, and the suspension cross beam is arranged between the longitudinal beam rear section middle cross beam at the front section of the longitudinal beam rear section and the longitudinal beam rear section middle cross beam at the rear section; middle lock cross beam connecting pieces, front suspension supporting pieces and rear suspension supporting pieces are sequentially arranged at the two ends of cross beams of the longitudinal beams. According to the utility model, the purposes of reducing the number of parts, being high in equipment production efficiency and reducing the cost can be achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of special vehicles, and in particular relates to an extrusion and die-casting composite integrated aluminum alloy frame for special vehicles, which is used for the chassis structure of special vehicles. Background Art

[0002] The frame is the most important load-bearing component of special vehicles. It connects various major assemblies and bears the combined effects of complex spatial forces. With the rapid development of logistics business, the continuous improvement of transportation speed and the strict control of carbon emissions, it is necessary to develop a frame structure with high strength, high quality, light weight and excellent comprehensive performance.

[0003] At present, most of the frames of special vehicles are made of steel, which has a large design load-bearing capacity but a bulky structure, high energy consumption, large emissions, low recycling rate, and is prone to corrosion. A small number of them have begun to use extruded aluminum alloy frames, which are light and have improved corrosion resistance, but they have a large number of parts, large welding deformation and strength loss, and low production and assembly efficiency. Utility Model Content

[0004] In view of the deficiencies in the prior art, the utility model provides an extruded and die-cast composite integrated aluminum alloy frame for special vehicles, which has high production efficiency, light weight, strong corrosion resistance and high load-bearing capacity.

[0005] An extruded and die-cast composite integrated aluminum alloy frame for special vehicles, comprising two identical longitudinal beams arranged side by side, and a plurality of cross beams arranged in parallel between the two longitudinal beams;

[0006] The cross beam comprises a longitudinal beam front section middle cross beam, a leg cross beam, a longitudinal beam rear section middle cross beam, a middle locking cross beam, and a suspension cross beam, wherein the longitudinal beam front section middle cross beam is arranged at the longitudinal beam front section, the connection between the longitudinal beam front section and the longitudinal beam middle section, and the longitudinal beam middle section, the leg cross beam is arranged at the connection between the longitudinal beam middle section and the longitudinal beam rear section, the longitudinal beam rear section middle cross beam is arranged at the front section and the rear section of the longitudinal beam rear section, the middle locking cross beam is arranged between the longitudinal beam rear section middle cross beam and the longitudinal beam rear section front section, and the suspension cross beam is arranged between the longitudinal beam rear section middle cross beam and the longitudinal beam rear section front section and the longitudinal beam rear section;

[0007] A center-locking crossbeam connector, a front suspension support member, and a rear suspension support member are sequentially arranged at both ends of the crossbeam of the longitudinal beam.

[0008] The longitudinal beam comprises a longitudinal beam front section, a longitudinal beam middle section and a longitudinal beam rear section which are connected in sequence by bolts.

[0009] The front section and the rear section of the longitudinal beam are extruded profiles, and the middle section of the longitudinal beam is a casting.

[0010] The cross section of the front section of the longitudinal beam is a double I-shaped structure, and the double webs in the middle form a closed cavity. The thickness of the upper and lower wing plates of the front section of the longitudinal beam is 14-20 mm, and the thickness of the middle web is 5-8 mm.

[0011] The middle section of the longitudinal beam includes two completely identical castings, which are arranged opposite to each other and have a "]"-shaped cross-section. The front end of the middle section of the longitudinal beam extends forward and is directly overlapped on the wing plate of the front section of the longitudinal beam. The side surfaces of the two castings that are in contact with the front section of the longitudinal beam are respectively joint surface one and joint surface two, and the surfaces of the wing plate of the front section of the longitudinal beam and the middle section of the longitudinal beam are respectively joint surface three and joint surface four; the rear end of the middle section of the longitudinal beam extends backward and is directly overlapped on the wing plate of the rear section of the longitudinal beam. The side surfaces of the two castings that are in contact with the rear section of the longitudinal beam are respectively joint surface five and joint surface six, and the surfaces of the wing plate of the rear section of the longitudinal beam and the middle section of the longitudinal beam are respectively joint surface seven and joint surface eight.

[0012] The middle section of the longitudinal beam serves as a transition section, and the joint surfaces 1 and 2 of the middle section of the longitudinal beam are fitted and pressed with the joint surfaces 3 and 4, and the joint surfaces 5 and 6 of the middle section of the longitudinal beam are fitted and pressed with the joint surfaces 7 and 8 of the rear section of the longitudinal beam.

[0013] The rear section of the longitudinal beam is made of high-strength aluminum alloy extruded profiles with a yield strength greater than 230 MPa and a large-section circumscribed circle diameter greater than 800 mm. The thickness of the upper and lower wing plates is 16 to 25 mm, and the thickness of the middle web is 10 to 15 mm.

[0014] The number of cross beams in the front section of the longitudinal beam is 3, the number of leg cross beams is 1, the number of cross beams in the rear section of the longitudinal beam is 5, specifically 4 in the front section and 1 in the rear section, the number of center lock cross beams is 1, specifically arranged between the middle cross beam in the rear section of the third longitudinal beam and the middle cross beam in the rear section of the fourth longitudinal beam; the number of suspension cross beams is 4.

[0015] The middle cross beam of the front section of the longitudinal beam adopts a small cross-section structure without reinforcement ribs whose circumscribed circle diameter is less than 250mm, the cross section is I-shaped and closed at both ends, and five through holes are evenly spaced on the middle longitudinal web as five weight-reducing hollow structures; the cross sections of the leg cross beam and the middle lock cross beam are I-shaped and closed at both ends, three through holes are evenly spaced on the middle longitudinal web as three weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes; waist-shaped holes are opened at both ends of the leg cross beam; the cross section of the suspension cross beam is I-shaped and closed at both ends, three through holes are evenly spaced on the middle longitudinal web as three weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes; the middle cross beam of the rear section of the longitudinal beam adopts a medium cross section with an circumscribed circle diameter of 250mm-800mm and adds reinforcement ribs for an integrated casting structure, the cross section is I-shaped and closed at both ends, four through holes are evenly spaced on the middle longitudinal web as four weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes.

[0016] Two ends of the cross beam of the rear section of the longitudinal beam are sequentially provided with a middle lock cross beam connector, a front suspension support member, and a rear suspension support member. Specifically, the middle lock cross beam connector includes a pair of two identical connectors, which are arranged on both sides of the longitudinal beam and located at both ends of the middle lock cross beam. Two front suspension support members are arranged on the outside of the longitudinal beam and correspond to two of the suspension cross beams respectively. Two rear suspension support members are arranged on the outside of the longitudinal beam and correspond to the other two suspension cross beams respectively. The two rear suspension support members are arranged closer to the tail end of the longitudinal beam than the two front suspension support members.

[0017] The rear suspension support member and the front suspension support member are leg-type support members with two legs; the front sides of the rear suspension support member and the front suspension support member are provided with reinforcing rib plates, and the rear sides are provided with criss-crossing reinforcing ribs; the center lock crossbeam connecting member is a box-type semi-enclosed structure, and the side walls of the center lock crossbeam connecting member are additionally provided with reinforcing ribs.

[0018] The beneficial effects of the utility model are as follows: the extrusion and die-casting composite integrated aluminum alloy frame provided by the utility model fully utilizes the advantages of both extrusion and casting production, adopts extrusion profiles and castings combined with reasonable layout and cross-sectional design, and solves the problems of bulky structural design of steel frames, high energy consumption, large number of extruded aluminum alloy frame parts, large welding deformation and strength loss, and low production and assembly efficiency. The utility model adopts bolt connections throughout, without welding deformation and strength loss, reduces the number of parts, achieves the goal of lightweight, improves the strength and rigidity of the frame, ensures reliability, realizes novel design structure, light weight, and strong corrosion resistance, and at the same time achieves the goal of reducing the number of parts, high production equipment efficiency, and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of an extruded and die-cast composite integrated aluminum alloy frame for a special vehicle is provided for the utility model;

[0020] Figure 2 It is an explosion attempt of the utility model;

[0021] Figure 3 It is a schematic diagram of the longitudinal beam in the utility model;

[0022] Figure 4 for Figure 3 AA section view;

[0023] Figure 5 for Figure 3 CC section view;

[0024] Figure 6 for Figure 3 DD section view;

[0025] Figure 7 for Figure 3 BB section view;

[0026] Figure 8 It is a schematic diagram of the front section of the longitudinal beam in the utility model;

[0027] Fig. 9 It is a front view of the front section of the longitudinal beam in the utility model (wherein Figure (a) is a main view, Figure (b) is a left view, and Figure (c) is a top view);

[0028] Fig.10 It is a schematic diagram of the middle section of the longitudinal beam in the utility model;

[0029] Fig.11 It is a front view of the middle section of the longitudinal beam in the utility model (wherein Figure (a) is the main view, Figure (b) is the left view, Figure (c) is the right view, and Figure (d) is the top view);

[0030] Fig.12 It is a schematic diagram of the rear section of the longitudinal beam in the utility model;

[0031] Fig.13 It is a front view of the rear section of the longitudinal beam in the utility model (wherein Figure (a) is a main view, Figure (b) is a left view, Figure (c) is a right view, and Figure (d) is a top view);

[0032] Fig.14 It is a schematic diagram of the cross beam 2 in the front section of the longitudinal beam in the utility model;

[0033] Fig.15 It is a front view of the cross beam 2 in the front section of the longitudinal beam in the utility model (Figure (b) is the main view, and Figure (a) is the AA section view of Figure (b));

[0034] Fig.16 It is a schematic diagram of the outrigger crossbeam and the middle lock crossbeam in the utility model;

[0035] Fig.17 It is a front view of the leg crossbeam and the middle lock crossbeam in the utility model (Figure (b) is the main view, and Figure (a) is the AA section view of Figure (b));

[0036] Fig.18 It is a schematic diagram of the suspension crossbeam in the utility model;

[0037] Fig.19 It is a front view of the suspension crossbeam in the utility model (wherein Figure (b) is the main view and Figure (a) is the AA section view of Figure (b));

[0038] Fig. 20 It is a schematic diagram of the cross beam in the rear section of the longitudinal beam in the utility model;

[0039] Fig.21 It is a front view of the cross beam in the rear section of the longitudinal beam in the utility model (Figure (b) is the main view, and Figure (a) is the AA section view of Figure (b));

[0040] Fig. 22 It is a schematic diagram of the front side of the rear suspension support member in the utility model;

[0041] Fig.23 It is a schematic diagram of the rear side surface of the rear suspension support member in the utility model;

[0042] Fig.24 It is a schematic diagram of the front side of the front suspension support member in the utility model;

[0043] Fig.25 It is a schematic diagram of the rear side of the front suspension support member in the utility model;

[0044] Fig.26 It is a schematic diagram of the rear side of the middle lock beam connecting member in the utility model;

[0045] Fig. 27 This is a schematic diagram of an application example of the utility model;

[0046] Fig.28 It is the stress cloud diagram of the frame under the bumpy working condition for the typical working condition strength analysis of the utility model;

[0047] Fig.29 The stress cloud diagram of the frame under braking condition for the typical working condition strength analysis of the utility model;

[0048] Fig.30 The stress cloud diagram of the frame under steering condition for the typical working condition strength analysis of the utility model;

[0049] Fig.31 It is a stress cloud diagram of the frame under torsion condition for the typical working condition strength analysis of the utility model;

[0050] in,

[0051] 1-longitudinal beam, 11-front section of longitudinal beam, 12-middle section of longitudinal beam, 13-rear section of longitudinal beam, 111-joining surface three, 112-joining surface four, 121-joining surface one, 122-joining surface two, 123-joining surface five, 124-joining surface six, 131-joining surface seven, 132-joining surface eight, 2-middle cross beam of front section of longitudinal beam, 3-leg cross beam, 4-middle cross beam of rear section of longitudinal beam, 5-middle lock cross beam, 6-suspension cross beam, 7-rear suspension support, 8-front suspension support, 9-middle lock cross beam connecting piece. DETAILED DESCRIPTION

[0052] In order to better explain the present invention and facilitate understanding, the technical scheme and effects of the present invention are described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0053] like Figure 1-2 As shown, an extruded and die-cast composite integrated aluminum alloy frame for special vehicles includes two identical longitudinal beams 1 arranged side by side, and 14 cross beams are arranged in parallel between the two longitudinal beams 1.

[0054] like Figure 3-Figure 7 As shown, the longitudinal beam 1 comprises a longitudinal beam front section 11, a longitudinal beam middle section 12 and a longitudinal beam rear section 13 which are connected in sequence by bolts, wherein the longitudinal beam front section 11 and the longitudinal beam rear section 13 are extruded profiles, and the longitudinal beam middle section 12 is a casting. Figure 8-Figure 13 As shown, the cross section of the longitudinal beam front section 11 is a double I-shaped structure, and the double webs in the middle form a closed cavity to improve the bending and compression resistance of the front end of the longitudinal beam; in this embodiment, the thickness of the upper and lower wing plates of the longitudinal beam front section 11 is 14mm, and the thickness of the middle web is 6mm. The longitudinal beam middle section 12 includes two identical castings, which are arranged oppositely and have a "]"-shaped cross section. The front end of the longitudinal beam middle section 12 extends forward and directly overlaps the wing plates of the longitudinal beam front section 11. The side surfaces of the two castings that fit the longitudinal beam front section 11 are joint surface 121 and joint surface 2 122 respectively, and the surfaces of the wing plates of the longitudinal beam front section 11 and the longitudinal beam middle section 12 that fit are joint surface 3 111 and joint surface 4 112 respectively. The rear end of the longitudinal middle section 12 extends backwards and directly overlaps the wing plate of the longitudinal rear section 13. The sides of the two castings that fit with the longitudinal rear section 13 are the joint surface 5 123 and the joint surface 6 124, and the faces of the wing plate of the longitudinal rear section 13 that fit with the longitudinal middle section 12 are the joint surface 7 131 and the joint surface 8 132. The longitudinal middle section 12 serves as a transition section. The joint surface 1 121 and the joint surface 2 122 of the longitudinal middle section 12 fit and press with the joint surface 3 111 and the joint surface 4 112. The joint surface 5 123 and the joint surface 6 124 of the longitudinal middle section 12 fit and press with the joint surface 7 131 and the joint surface 8 132 of the longitudinal rear section 13, so that the entire longitudinal beam is connected together, which is beneficial to the transmission of force. At the same time, the transition section is smoother, the strength of the transition connection area of ​​the middle section is enhanced, which is beneficial to the transmission and balance of force. At the same time, it is easy to assemble and the operation is quick and convenient. The rear section 13 of the longitudinal beam is made of high-strength aluminum alloy extruded profile with a yield strength greater than 230 MPa and a large-section aluminum alloy extruded profile with an circumscribed circle diameter greater than 800 mm. The thickness of the upper and lower wing plates is 16 mm, and the thickness of the middle web is 10 mm. It takes advantage of the extrusion process, has high production efficiency and stable quality.

[0055] like Figure 14-Figure 21As shown, there are 14 cross beams in total, including a longitudinal beam front section middle cross beam 2, a leg cross beam 3, a longitudinal beam rear section middle cross beam 4, a middle locking cross beam 5, and a suspension cross beam 6. The longitudinal beam front section middle cross beam 2 is 3 in number, and is arranged at the longitudinal beam front section 11, the connection between the longitudinal beam front section 11 and the longitudinal beam middle section 12, and the longitudinal beam middle section 12. The leg cross beam 3 is 1 in number, and is arranged at the connection between the longitudinal beam middle section 12 and the longitudinal beam rear section 13. The longitudinal beam rear section middle cross beam 4 is 5 in number, and is arranged at the front section and the rear section of the longitudinal beam rear section 13, specifically, 4 in number, and 1 in number. The middle locking cross beam 5 is 1 in number, and is arranged between the longitudinal beam rear section middle cross beam 4 in the front section of the longitudinal beam rear section 13, specifically, between the third longitudinal beam rear section middle cross beam 4 and the fourth longitudinal beam rear section middle cross beam 4. The number of suspension cross members 6 is four, and they are disposed between four cross members in the front and rear sections of the longitudinal beam rear section 13 .

[0056] The cross beam 2 in the front section of the longitudinal beam adopts a small cross-section structure without reinforcement ribs with a circumscribed circle diameter less than 250mm, an I-shaped cross section and closed at both ends, and five through holes are evenly spaced on the middle longitudinal web as five weight-reducing empty structures to achieve the goal of lightweight. The leg cross beam 3, the middle lock cross beam 5, and the suspension cross beam 6 are important load-bearing positions and important channels for transmitting force of the frame. They adopt a large cross-section with added reinforcement ribs and an integrated casting structure with three weight-reducing empty structures to ensure the load-bearing capacity of the frame. The cross sections of the leg cross beam 3 and the middle lock cross beam 5 are I-shaped and closed at both ends, and three through holes are evenly spaced on the middle longitudinal web as three weight-reducing empty structures, and reinforcement ribs are arranged around and between the through holes; waist-shaped holes are oppositely opened on the two ends of the leg cross beam 3. The cross section of the suspension cross beam 6 is I-shaped and closed at both ends, and three through holes are evenly spaced on the middle longitudinal web as three weight-reducing empty structures, and reinforcement ribs are arranged around and between the through holes. The cross beam 4 in the rear section of the longitudinal beam is an important auxiliary load-bearing component of the frame. It adopts an integrated casting structure with a medium cross-section with an circumscribed circle diameter of 250mm-800mm and added reinforcing ribs. The cross-section is I-shaped and closed at both ends. Four through holes are evenly spaced on the middle longitudinal web as four weight-reducing hollow structures, and reinforcing ribs are arranged around and between the through holes to take into account both load-bearing and lightweight goals.

[0057] The cross beams are integrated into one component from three traditional components, which reduces the number of components and production assembly processes, is conducive to improving production efficiency and reducing production costs. At the same time, all bolt connections are used without welding deformation and strength loss, which improves the load-bearing capacity of the frame in complex environments such as braking, steering, torsion, and bending during vehicle driving. The structural layout of the cross beams is reasonably allocated according to the position and load-bearing requirements of each cross beam in the frame, and different cross-sectional shapes and design structures are used to achieve the goals of lightweight and high performance.

[0058] The two ends of the cross beam of the rear section 13 of the longitudinal beam are sequentially provided with a center lock cross beam connector 9, two front suspension support members 8, and two rear suspension support members 7, which are important connection accessories on the frame. Specifically, the center lock cross beam connector 9 includes a pair of two identical connectors, which are arranged on both sides of the longitudinal beam 1 and located at both ends of the center lock cross beam 5. The two front suspension support members 8 are arranged on the outside of the longitudinal beam 1, corresponding to two of the suspension cross beams 6 respectively. The two rear suspension support members 7 are arranged on the outside of the longitudinal beam 1, corresponding to the other two suspension cross beams 6 respectively, and the two rear suspension support members 7 are arranged closer to the tail end of the longitudinal beam 1 than the two front suspension support members 8.

[0059] like Figure 22-Figure 26 As shown, the rear suspension support 7 and the front suspension support 8 are important parts for supporting and transmitting the load from the road surface through the leaf spring. They are leg-type support parts with two legs. The front sides of the rear suspension support 7 and the front suspension support 8 are provided with reinforcing ribs, and the rear sides are provided with criss-crossing reinforcing ribs. The rear suspension support 7 and the front suspension support 8 are both welded from three traditional parts and integrated into one part. The setting of the reinforcing ribs and reinforcing ribs improves the load-bearing capacity and assembly efficiency and reduces the cost. The middle lock beam connector 9 is an important connecting part for supporting the upper cargo. It is welded from four traditional parts and integrated into one high-strength casting. The middle lock beam connector 9 is a box-type semi-enclosed structure. The side walls of the middle lock beam connector 9 are additionally provided with reinforcing ribs to increase the load-bearing capacity.

[0060] The extrusion and die-casting composite integrated aluminum alloy frame provided by the utility model can be widely used in special vehicles such as vans, tank trucks, container transport vehicles, etc. Fig. 27 The following is a schematic diagram of a container transport vehicle application case. The frame is subjected to different loads during use. Sufficient strength and dynamic load-bearing capacity must be ensured during design to ensure that the frame has sufficient resistance to damage under load to ensure safe and reliable operation of the vehicle. Strength analysis of four typical working conditions, namely, bumping, braking, turning and twisting, is carried out based on the actual use of the frame. The stress cloud diagram of the frame under bumping conditions is shown in the figure below. Fig.28 As shown in the figure, the stress cloud diagram of the frame under braking condition is as follows Fig.29 As shown in the figure, the stress cloud diagram of the frame under steering condition is as follows Fig.30 As shown in the figure, the stress cloud diagram of the frame under torsion condition is as follows Fig.31 As shown, the results show that the frame meets the strength requirements.

Claims

1. An extrusion and die-casting composite integrated aluminum alloy frame for special vehicles, characterized in that: It comprises two identical longitudinal beams arranged side by side, and a plurality of transverse beams arranged in parallel between the two longitudinal beams; The cross beam comprises a longitudinal beam front section middle cross beam, a leg cross beam, a longitudinal beam rear section middle cross beam, a middle locking cross beam, and a suspension cross beam, wherein the longitudinal beam front section middle cross beam is arranged at the longitudinal beam front section, the connection between the longitudinal beam front section and the longitudinal beam middle section, and the longitudinal beam middle section, the leg cross beam is arranged at the connection between the longitudinal beam middle section and the longitudinal beam rear section, the longitudinal beam rear section middle cross beam is arranged at the front section and the rear section of the longitudinal beam rear section, the middle locking cross beam is arranged between the longitudinal beam rear section middle cross beam and the longitudinal beam rear section front section, and the suspension cross beam is arranged between the longitudinal beam rear section middle cross beam and the longitudinal beam rear section front section and the longitudinal beam rear section; A center-locking crossbeam connector, a front suspension support member, and a rear suspension support member are sequentially arranged at both ends of the crossbeam of the longitudinal beam.

2. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 1, characterized in that: The longitudinal beam comprises a longitudinal beam front section, a longitudinal beam middle section and a longitudinal beam rear section which are connected in sequence by bolts.

3. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: The front section and the rear section of the longitudinal beam are extruded profiles, and the middle section of the longitudinal beam is a casting.

4. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: The cross section of the front section of the longitudinal beam is a double I-shaped structure, and the double webs in the middle form a closed cavity. The thickness of the upper and lower wing plates of the front section of the longitudinal beam is 14-20 mm, and the thickness of the middle web is 5-8 mm.

5. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: The longitudinal beam middle section comprises two completely identical castings, which are arranged opposite to each other and have a "]"-shaped cross section. The front end of the longitudinal beam middle section extends forward and is directly overlapped on the wing plate of the longitudinal beam front section. The side surfaces of the two castings that are in contact with the longitudinal beam front section are respectively joint surface one and joint surface two, and the surfaces of the wing plate of the longitudinal beam front section and the longitudinal beam middle section that are in contact are respectively joint surface three and joint surface four; the rear end of the longitudinal beam middle section extends backward and is directly overlapped on the wing plate of the longitudinal beam rear section. The side surfaces of the two castings that are in contact with the longitudinal beam rear section are respectively joint surface five and joint surface six, and the surfaces of the wing plate of the longitudinal beam rear section and the longitudinal beam middle section that are in contact are respectively joint surface seven and joint surface eight.

6. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: The middle section of the longitudinal beam serves as a transition section, and the joint surfaces 1 and 2 of the middle section of the longitudinal beam are fitted and pressed with the joint surfaces 3 and 4, and the joint surfaces 5 and 6 of the middle section of the longitudinal beam are fitted and pressed with the joint surfaces 7 and 8 of the rear section of the longitudinal beam.

7. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: The rear section of the longitudinal beam is made of high-strength aluminum alloy extruded profiles with a yield strength greater than 230 MPa and a large-section circumscribed circle diameter greater than 800 mm. The thickness of the upper and lower wing plates is 16 to 25 mm, and the thickness of the middle web is 10 to 15 mm.

8. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 1, characterized in that: The number of cross beams in the front section of the longitudinal beam is 3, the number of leg cross beams is 1, the number of cross beams in the rear section of the longitudinal beam is 5, specifically 4 in the front section and 1 in the rear section, the number of center lock cross beams is 1, specifically arranged between the middle cross beam in the rear section of the third longitudinal beam and the middle cross beam in the rear section of the fourth longitudinal beam; the number of suspension cross beams is 4.

9. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 1, characterized in that: The middle cross beam of the front section of the longitudinal beam adopts a small cross-section structure without reinforcement ribs whose circumscribed circle diameter is less than 250mm, the cross section is I-shaped and closed at both ends, and five through holes are evenly spaced on the middle longitudinal web as five weight-reducing hollow structures; the cross sections of the leg cross beam and the middle lock cross beam are I-shaped and closed at both ends, three through holes are evenly spaced on the middle longitudinal web as three weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes; waist-shaped holes are opened at both ends of the leg cross beam; the cross section of the suspension cross beam is I-shaped and closed at both ends, three through holes are evenly spaced on the middle longitudinal web as three weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes; the middle cross beam of the rear section of the longitudinal beam adopts a medium cross section with an circumscribed circle diameter of 250mm-800mm and adds reinforcement ribs for an integrated casting structure, the cross section is I-shaped and closed at both ends, four through holes are evenly spaced on the middle longitudinal web as four weight-reducing hollow structures, and reinforcement ribs are arranged around and between the through holes.

10. The extrusion and die-casting composite integrated aluminum alloy frame for special vehicles according to claim 2, characterized in that: Two ends of the cross beam of the rear section of the longitudinal beam are sequentially provided with a middle lock cross beam connector, a front suspension support member, and a rear suspension support member. Specifically, the middle lock cross beam connector includes a pair of two identical connectors, which are arranged on both sides of the longitudinal beam and located at both ends of the middle lock cross beam. Two front suspension support members are arranged on the outside of the longitudinal beam and correspond to two of the suspension cross beams respectively. Two rear suspension support members are arranged on the outside of the longitudinal beam and correspond to the other two suspension cross beams respectively. The two rear suspension support members are arranged closer to the tail end of the longitudinal beam than the two front suspension support members. The rear suspension support member and the front suspension support member are leg-type support members with two legs; the front sides of the rear suspension support member and the front suspension support member are provided with reinforcing rib plates, and the rear sides are provided with criss-crossing reinforcing ribs; the center lock crossbeam connecting member is a box-type semi-enclosed structure, and the side walls of the center lock crossbeam connecting member are additionally provided with reinforcing ribs.

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