Integral Rear Subframe and Its Casting Method

Abstract

The present invention discloses an integrated rear subframe and a casting method thereof, comprising a front crossbeam; a rear crossbeam; and side beams; the top of the front crossbeam is provided with two first mounting holes, the side beams are provided with a drive shaft hole and a second mounting hole, the ends of the front crossbeam and the rear crossbeam extend outward and are respectively connected to a front fixing portion and a rear fixing portion, a first mounting assembly, a second mounting assembly, a third mounting assembly, and a fourth mounting assembly are provided on the side beam between the front fixing portion and the rear fixing portion, the first mounting assembly is connected to the second mounting assembly, the third mounting assembly is located above the drive shaft hole, and the fourth mounting assembly is located below the drive shaft hole and near the rear fixing portion. The casting method of the present invention has simple steps and can not only improve the casting processing quality of the rear subframe, but also improve the accuracy of fluorescent flaw detection of the rear subframe casting, reduce the labor intensity of manual inspection, and improve the production quality of the rear subframe.

Description

Technical Field

[0001] The invention relates to an integrated rear subframe and a casting method thereof. Background Art

[0002] The rear subframe is the skeleton of the rear axle and an important component of the rear axle.

[0003] The main function of the rear subframe is to reduce the impact of road vibration on the vehicle body and increase the connection stiffness of the suspension system, thereby improving the comfort and stability of the vehicle during driving.

[0004] The rear subframe of the prior art has poor stability and poses certain safety hazards. At the same time, the rear subframe requires manual inspection during the casting process, which not only has low inspection accuracy, but also increases the labor intensity of manual operation and reduces product quality. Summary of the Invention

[0005] The present invention aims to address the deficiencies in the prior art and to provide a technical solution for an integrated rear subframe and a casting method thereof, which not only improves the stability and reliability of the rear subframe installation, but also enhances the safety of the entire vehicle installation and extends the service life. The casting method has simple steps and can not only improve the casting processing quality of the rear subframe, but also improve the accuracy of fluorescent flaw detection of the rear subframe casting, reduce the labor intensity of manual inspection, and improve the production quality of the rear subframe.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] One-piece rear subframe, including

[0008] front cross member;

[0009] rear cross member;

[0010] and side members, the front cross member is connected to the rear cross member through the side members, and forms a closed structure;

[0011] Its characteristics are:

[0012] Two first mounting holes are provided on the top of the front cross beam, and a drive shaft hole and a second mounting hole are provided on the side beam. The two ends of the front cross beam and the rear cross beam extend outward and are respectively connected to the front fixing part and the rear fixing part. A first mounting assembly, a second mounting assembly, a third mounting assembly and a fourth mounting assembly are provided on the side beam between the front fixing part and the rear fixing part. The first mounting assembly is connected to the second mounting assembly, the third mounting assembly is located above the drive shaft hole, and the fourth mounting assembly is located below the drive shaft hole and close to the rear fixing part. Through the design of the above structure, not only the stability and reliability of the rear subframe installation can be improved, but also the safety of the vehicle installation is improved and the service life is extended.

[0013] Furthermore, the interiors of the front cross member, the rear cross member and the side members are all hollow structures, which facilitates reducing the overall weight of the rear subframe without affecting the mass of the rear subframe.

[0014] Furthermore, through holes are provided inside the front fixing part and the rear fixing part, and reinforcing ribs are provided on the outer side surfaces of the front fixing part and the rear fixing part to facilitate the fixed installation between the rear subframe and the vehicle body. The reinforcing ribs improve the strength and stability of the front fixing part and the rear fixing part.

[0015] Furthermore, the first mounting assembly includes two first mounting plates arranged parallel to each other. The first mounting plates are provided with first fixing holes. The first mounting plates are close to the front fixing portion and are used for installation and disassembly of components.

[0016] Furthermore, the second mounting assembly includes two second mounting plates arranged parallel to each other, the second mounting plates are provided with second fixing holes, the second mounting plates are connected to the first mounting plate, and are located below the first mounting plate for installation and disassembly of parts.

[0017] Furthermore, the third mounting assembly includes two third mounting plates arranged parallel to each other, and the third mounting plates are provided with third fixing holes for installation and removal of components.

[0018] Furthermore, the fourth mounting assembly includes two fourth mounting plates arranged parallel to each other, and the fourth mounting plates are provided with fourth fixing holes for installation and removal of parts.

[0019] The method for casting the integrated rear subframe is characterized by comprising the following steps:

[0020] S1, sand core making

[0021] Determine the size of the sand core according to the design size of the rear subframe and make the corresponding sand core;

[0022] S2. Melting and degassing

[0023] a. Prepare aluminum alloy and heat it in a melting furnace to melt it;

[0024] b. Then adjust the temperature of the aluminum liquid to 750℃~780℃ for modification;

[0025] c. Then adjust the temperature of the aluminum liquid to 700℃~730℃ for refining treatment;

[0026] d. Finally, skim the slag and transfer the aluminum alloy liquid into the holding furnace of the low-pressure casting machine. Adjust the temperature of the aluminum alloy liquid to 680℃~700℃ for pouring. At the same time, remove the waste gas generated during the smelting process.

[0027] S3, low pressure casting

[0028] a. Set the low-pressure casting process parameters: the liquid rising pressure is 0.03-0.05 MPa, the liquid rising rate is 30-60 mm / s, the filling pressure is 0.06-0.08 MPa, the filling rate is 50-70 mm / s, the holding pressure is 0.12-0.16 MPa, the holding time is 15-30 seconds, and the pressure is released;

[0029] b. Complete the entire pouring process of liquid raising, mold filling, pressure holding, and pressure relief, open the mold, and take out the casting;

[0030] S4, Fluorescent flaw detection

[0031] a. First, the rear subframe casting is suspended on the clamping mechanism in sequence. The touch screen on the box controls the driving mechanism to move the lifting mechanism, lowering the rear subframe casting into the cleaning tank of the box. The cleaning tank is equipped with a heating plate and a brush connected to a servo motor. The servo motor drives the brush to rotate and remove oil and rust spots on the surface of the rear subframe casting.

[0032] b. Then, the clamping mechanism is driven to rise by the lifting mechanism. During the rising process, the hot air drying mechanism is activated to evaporate the moisture on the surface of the rear subframe casting;

[0033] c. The driving mechanism then drives the lifting mechanism to move horizontally, causing the clamping mechanism to move the rear subframe casting to the top of the immersion tank in the box. The rear subframe casting is lowered into the immersion tank via the lifting mechanism and the clamping mechanism, and is immersed in the fluorescent liquid.

[0034] d. After the soaking is completed, the clamping mechanism is driven to rise by the lifting mechanism. During the rising process, the hot air drying mechanism is activated. The fluorescent liquid on the surface of the rear subframe casting is first washed through the water outlet on the hot air drying mechanism. Then, the developer is sprayed on the surface of the rear subframe casting by the hot air drying mechanism and low-temperature drying is performed.

[0035] e. Finally, the driving mechanism drives the lifting mechanism to move horizontally, so that the clamping mechanism drives the rear subframe casting to move into the fluorescent flaw detection tank of the box. The fluorescent flaw detection lamp and camera are turned on, and the fluorescence emitted by the fluorescent liquid is displayed on the touch screen through the camera;

[0036] The fluorescent flaw detection process is simple and can not only realize automatic cleaning, drying and fluorescent flaw detection of the rear subframe casting, but also greatly improve the efficiency of fluorescent flaw detection, reduce manual operation intensity, improve detection accuracy and reduce the defective rate.

[0037] The clamping mechanism includes a horizontal rod, a vertical column is provided parallel to the bottom of the horizontal rod, a first guide groove is provided on the vertical column, a lifting rod is movably connected between two adjacent vertical columns, the lifting rod is connected to the vertical column through a first fastener, a second guide groove is provided on the lifting rod, and a second fastener is connected to the second guide groove; the lifting rod can move up and down along the vertical column to adjust the distance between the two lifting rods, and the second fastener can move along the lifting rod to adjust the distance between the two second fasteners, thereby meeting the clamping requirements of rear subframes of different sizes and shapes, and greatly improving the efficiency of fluorescent flaw detection.

[0038] The hot air drying mechanism includes a hot air box and a blowing plate. The blowing plate is connected to the hot air box through a pipe. The blowing plate is provided with an inclined surface. The inclined surface is provided with an air outlet and a water outlet. The water outlet is connected to an external water pipe. The hot air box transports hot air to the blowing plate through the pipe, and the air outlet is used to dry the rear subframe. The water outlet is used to rinse the rear subframe.

[0039] S5. Heat treatment

[0040] a. Place the rear subframe casting in an aluminum alloy solution treatment device, heat it to 550°C, keep it warm for 5 to 8 hours, and then place it in water within 1 minute. The water temperature should be controlled at 80°C.

[0041] b. Cool the solution-treated rear subframe casting to room temperature and keep it at room temperature for 5 hours;

[0042] c. Transfer to aluminum alloy aging treatment equipment, aging temperature is 150℃~180℃, holding time is 5~8h, take out and air cool;

[0043] S6. Polishing

[0044] The heat-treated rear subframe casting is polished by a polishing machine;

[0045] S7, X-ray detection

[0046] The polished rear subframe casting is inspected using low-energy X-rays using an X-ray detector;

[0047] S8, cleaning and drying

[0048] The qualified rear subframes are cleaned, dried and packed.

[0049] The casting method has simple steps and can not only improve the casting processing quality of the rear subframe, but also improve the fluorescence flaw detection accuracy of the rear subframe casting, reduce the labor intensity of manual detection, and improve the production quality of the rear subframe.

[0050] Furthermore, the driving mechanism in step S4 process a includes a first motor, a first screw and a baffle. The first motor and the baffle are arranged on the side of the box body. The first motor is connected to the baffle through the first screw. The lifting mechanism is connected to the first screw. The first motor drives the first screw to rotate, and then drives the lifting mechanism to move horizontally, thereby realizing horizontal transportation of the rear sub-frame.

[0051] Furthermore, the lifting mechanism in step S4 process a includes a lower base plate, an upper top plate, a movable plate, a slider and a booster block, the slider is connected to the lower base plate, a guide rail is provided on the side of the box body, the slider is connected to the slide rail, the booster block is provided at the bottom of the slider, the booster block is connected to the first screw, the upper top plate is fixedly connected to the lower base plate through a guide rod, the movable plate is slidably connected to the guide rod, the lower base plate is provided with a second motor, the second motor is connected to a second screw, the second screw passes through the movable plate and is connected to the upper top plate, and the second screw is driven to rotate by the second motor, thereby driving the movable plate to move up and down, meeting the height adjustment requirements of the rear sub-frame, and the guide rod improves the connection strength and stability between the lower base plate and the upper top plate.

[0052] The present invention has the following beneficial effects due to the adoption of the above technical solution:

[0053] 1. The present invention can not only improve the stability and reliability of the rear subframe installation, but also improve the safety of the whole vehicle installation and extend the service life.

[0054] 2. The fluorescent flaw detection process is simple and can not only realize automatic cleaning, drying and fluorescent flaw detection of the rear subframe casting, but also greatly improve the efficiency of fluorescent flaw detection, reduce manual operation intensity, improve detection accuracy and reduce defective rate.

[0055] 3. The casting method of the present invention has simple steps, which can not only improve the casting processing quality of the rear subframe, but also improve the accuracy of fluorescent flaw detection of the rear subframe casting, reduce the labor intensity of manual inspection, and improve the production quality of the rear subframe. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention will be further described below in conjunction with the accompanying drawings:

[0057] Figure 1 Schematic diagram of the structure of the integrated rear subframe and the casting method thereof of the present invention;

[0058] Figure 2 for Figure 1 Schematic diagram of the structure in the A direction;

[0059] Figure 3 is a flow chart of the casting method of the present invention;

[0060] Figure 4 Schematic diagram of the structure of the fluorescent flaw detection equipment in the present invention;

[0061] Figure 5 for Figure 4 Schematic diagram of the structure in the B direction;

[0062] Figure 6 Schematic diagram of the structure of the clamping mechanism of the present invention;

[0063] Figure 7 This is a schematic diagram of the installation of the blowing plate in the present invention;

[0064] Figure 8 This is a schematic diagram of the installation of the fluorescent flaw detection lamp and camera in the present invention.

[0065] In the figure: 1-front crossbeam; 2-rear crossbeam; 3-side beam; 4-first mounting hole; 5-second mounting hole; 6-drive shaft hole; 7-front fixing portion; 8-rear fixing portion; 9-first mounting plate; 10-first fixing hole; 11-second mounting plate; 12-second fixing hole; 13-third mounting plate; 14-third fixing hole; 15-fourth mounting plate; 16-fourth fixing hole; 17-reinforcement rib; 18-through hole; 19-box; 20-touch screen; 21-cleaning tank; 22-immersion tank; 23-fluorescent flaw detection tank; 24-lifting mechanism; 25-clamping mechanism; 26-first liquid inlet pipe; 27-first liquid outlet pipe; 28-second Liquid inlet pipe; 29-second liquid outlet pipe; 30-guide rail; 31-first motor; 32-first screw; 33-baffle; 34-slider; 35-boost block; 36-lower base plate; 37-upper top plate; 38-movable plate; 39-second motor; 40-second screw; 41-guide rod; 42-hot air box; 43-horizontal rod; 44-column; 45-first guide groove; 46-first fastener; 47-lifting rod; 48-second guide groove; 49-second fastener; 50-fixed plate; 51-blowing plate; 52-inclined surface; 53-air outlet; 54-side panel; 55-fluorescent flaw detection lamp; 56-camera; 57-water outlet. DETAILED DESCRIPTION

[0066] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0067] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0068] It should be noted that the terms "first," "second," and so on in the description and claims of the present invention and the accompanying drawings are used to distinguish similar items and are not necessarily used to describe a specific order or precedence. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0069] like Figures 1 to 2 The figure shows the integrated rear subframe of the present invention, comprising a front crossbeam 1, a rear crossbeam 2, and side beams 3. The front crossbeam 1 is connected to the rear crossbeam 2 via the side beams 3, forming a closed structure. The interiors of the front crossbeam 1, rear crossbeam 2, and side beams 3 are all hollow, which facilitates reducing the overall weight of the rear subframe without compromising its quality.

[0070] Through holes 18 are provided inside the front fixing portion 7 and the rear fixing portion 8, and reinforcing ribs 17 are provided on the outer sides of the front fixing portion 7 and the rear fixing portion 8 to facilitate the fixed installation between the rear subframe and the vehicle body. The reinforcing ribs 17 improve the strength and stability of the front fixing portion 7 and the rear fixing portion 8.

[0071] Two first mounting holes 4 are provided at the top of the front cross beam 1, and a drive shaft hole 6 and a second mounting hole 5 are provided at the side beam 3. The two ends of the front cross beam 1 and the rear cross beam 2 extend outward and are respectively connected to a front fixing portion 7 and a rear fixing portion 8. A first mounting assembly, a second mounting assembly, a third mounting assembly and a fourth mounting assembly are provided on the side beam 3 between the front fixing portion 7 and the rear fixing portion 8.

[0072] The first mounting assembly is connected to the second mounting assembly and includes two parallel first mounting plates 9 with first fixing holes 10. The first mounting plates 9 are located near the front fixing portion 7 and are used for installing and removing components. The second mounting assembly includes two parallel second mounting plates 11 with second fixing holes 12. The second mounting plates 11 are connected to the first mounting plates 9 and are located below the first mounting plates 9 for installing and removing components.

[0073] The third mounting assembly is located above the drive shaft hole 6. The third mounting assembly includes two third mounting plates 13 arranged parallel to each other. The third mounting plates 13 are provided with third fixing holes 14 for installation and removal of components.

[0074] The fourth mounting assembly is located below the drive shaft hole 6 and near the rear fixing portion 8. It includes two parallel fourth mounting plates 15, each with fourth fixing holes 16 for mounting and removing components. This structural design not only improves the stability and reliability of the rear subframe installation, but also enhances the safety of the vehicle and extends its service life.

[0075] like Figures 3 to 8As shown, the invention shows a casting method of an integrated rear subframe, comprising the following steps:

[0076] S1, sand core making

[0077] Determine the size of the sand core according to the design size of the rear subframe and make the corresponding sand core;

[0078] S2. Melting and degassing

[0079] a. Prepare aluminum alloy and heat it in a melting furnace to melt it;

[0080] b. Then adjust the temperature of the aluminum liquid to 750℃~780℃ for modification;

[0081] c. Then adjust the temperature of the aluminum liquid to 700℃~730℃ for refining treatment;

[0082] d. Finally, skim the slag and transfer the aluminum alloy liquid into the holding furnace of the low-pressure casting machine. Adjust the temperature of the aluminum alloy liquid to 680℃~700℃ for pouring. At the same time, remove the waste gas generated during the smelting process.

[0083] S3, low pressure casting

[0084] a. Set the low-pressure casting process parameters: the liquid rising pressure is 0.03-0.05 MPa, the liquid rising rate is 30-60 mm / s, the filling pressure is 0.06-0.08 MPa, the filling rate is 50-70 mm / s, the holding pressure is 0.12-0.16 MPa, the holding time is 15-30 seconds, and the pressure is released;

[0085] b. Complete the entire pouring process of liquid raising, mold filling, pressure holding, and pressure relief, open the mold, and take out the casting;

[0086] S4, Fluorescent flaw detection

[0087] a. First, the rear subframe casting is sequentially suspended on the clamping mechanism 25. The touch screen 20 on the box 19 controls the driving mechanism to move the lifting mechanism 24, so that the rear subframe casting is lowered into the cleaning tank 21 of the box 19. The cleaning tank 21 is equipped with a heating plate and a brush. The brush is connected to a servo motor, which drives the brush to rotate to remove oil and rust on the surface of the rear subframe casting.

[0088] The clamping mechanism 25 includes a horizontal rod 43, a column 44 is provided parallel to the bottom of the horizontal rod 43, a first guide groove 45 is provided on the column 44, a lifting rod 47 is movably connected between two adjacent columns 44, the lifting rod 47 is connected to the column 44 through a first fastener 46, a second guide groove 48 is provided on the lifting rod 47, and a second fastener 49 is connected to the second guide groove 48; the lifting rod 47 can move up and down along the column 44 to adjust the distance between the two lifting rods 47, and the second fastener 49 can move along the lifting rod 47 to adjust the distance between the two second fasteners 49, thereby meeting the clamping requirements of rear subframes of different sizes and shapes, and greatly improving the efficiency of fluorescent flaw detection.

[0089] The hot air drying mechanism includes a hot air box 42 and a blowing plate 51. The blowing plate 51 is connected to the hot air box 42 via a pipe. The blowing plate 51 has an inclined surface 52, which is provided with an air outlet 53 and a water outlet 57. The water outlet 57 is connected to an external water pipe. The hot air box 42 delivers hot air to the blowing plate 51 via a pipe. The air outlet 53 dries the rear subframe, while the water outlet 57 rinses the rear subframe. The blowing plate 51 is connected to the housing 19 via a fixing plate 50.

[0090] The driving mechanism includes a first motor 31, a first screw 32 and a baffle 33. The first motor 31 and the baffle 33 are arranged on the side of the box body 19. The first motor 31 is connected to the baffle 33 through the first screw 32. The lifting mechanism 24 is connected to the first screw 32. The first motor 31 drives the first screw 32 to rotate, and then drives the lifting mechanism 24 to move horizontally, thereby realizing horizontal transportation of the rear subframe.

[0091] The lifting mechanism 24 includes a lower base plate 36, an upper top plate 37, a movable plate 38, a slider 34 and a booster block 35. The slider 34 is connected to the lower base plate 36. A guide rail 30 is provided on the side of the box body 19. The slider 34 is connected to the slide rail. The booster block 35 is provided at the bottom of the slider 34. The booster block 35 is connected to the first screw 32. The upper top plate 37 is fixedly connected to the lower base plate 36 through a guide rod 41. The movable plate 38 is slidably connected to the guide rod 41. The lower base plate 36 is provided with a second motor 39. The second motor 39 is connected to a second screw 40. The second screw 40 passes through the movable plate 38 and is connected to the upper top plate 37. The second motor 39 drives the second screw 40 to rotate, and then the movable plate 38 can be driven up and down to meet the height adjustment requirements of the rear subframe. The guide rod 41 improves the connection strength and stability between the lower base plate 36 and the upper top plate 37.

[0092] b. Then, the clamping mechanism 25 is driven to rise by the lifting mechanism 24. During the rising process, the hot air drying mechanism is activated to evaporate the moisture on the surface of the rear subframe casting;

[0093] c. The driving mechanism then drives the lifting mechanism 24 to move horizontally, causing the clamping mechanism 25 to move the rear subframe casting to above the immersion tank 22 of the box 19. The rear subframe casting is lowered into the immersion tank 22 via the lifting mechanism 24 and the clamping mechanism 25, and immersed in the fluorescent liquid.

[0094] A first liquid inlet pipe 26, a first liquid outlet pipe 27, a second liquid inlet pipe 28 and a second liquid outlet pipe 29 are provided on the side of the box body 19. The first liquid inlet pipe 26 and the first liquid outlet pipe 27 are connected to the cleaning tank, and the second liquid inlet pipe 28 and the second liquid outlet pipe 29 are connected to the immersion tank.

[0095] d. After the soaking is completed, the clamping mechanism 25 is driven to rise by the lifting mechanism 24. During the rising process, the hot air drying mechanism is activated to first rinse the fluorescent liquid on the surface of the rear subframe casting through the water outlet 57 on the hot air drying mechanism. Then, the developer is sprayed on the surface of the rear subframe casting by the hot air drying mechanism and then dried at a low temperature.

[0096] e. Finally, the driving mechanism drives the lifting mechanism 24 to move horizontally, so that the clamping mechanism 25 drives the rear subframe casting to move into the fluorescent flaw detection tank 23 of the box body 19, and the fluorescent flaw detection lamp 55 and the camera 56 are turned on. The fluorescence emitted by the fluorescent liquid is displayed on the touch screen 20 through the camera 56; a side panel 54 is provided in the fluorescent flaw detection tank 23, and the fluorescent flaw detection lamp 55 and the camera 56 are arranged on the side panel 54.

[0097] The fluorescent flaw detection process is simple and can not only realize automatic cleaning, drying and fluorescent flaw detection of the rear subframe casting, but also greatly improve the efficiency of fluorescent flaw detection, reduce manual operation intensity, improve detection accuracy and reduce the defective rate.

[0098] S5. Heat treatment

[0099] a. Place the rear subframe casting in an aluminum alloy solution treatment device, heat it to 550°C, keep it warm for 5 to 8 hours, and then place it in water within 1 minute. The water temperature should be controlled at 80°C.

[0100] b. Cool the solution-treated rear subframe casting to room temperature and keep it at room temperature for 5 hours;

[0101] c. Transfer to aluminum alloy aging treatment equipment, aging temperature is 150℃~180℃, holding time is 5~8h, take out and air cool;

[0102] S6. Polishing

[0103] The heat-treated rear subframe casting is polished by a polishing machine;

[0104] S7, X-ray detection

[0105] The polished rear subframe casting is inspected using low-energy X-rays using an X-ray detector;

[0106] S8, cleaning and drying

[0107] The qualified rear subframes are cleaned, dried and packed.

[0108] The casting method has simple steps and can not only improve the casting processing quality of the rear subframe, but also improve the fluorescence flaw detection accuracy of the rear subframe casting, reduce the labor intensity of manual detection, and improve the production quality of the rear subframe.

[0109] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements, or modifications based on the present invention to achieve substantially the same technical effects are all within the scope of protection of the present invention.

Claims

1. Casting method of integrated rear subframe, the integrated rear subframe includes front cross member; rear cross member; and side members, the front cross member being connected to the rear cross member via the side members to form a closed structure; Its characteristics are: The top of the front crossbeam is provided with two first mounting holes, the side beam is provided with a drive shaft hole and a second mounting hole, both ends of the front crossbeam and the rear crossbeam extend outward and are respectively connected to a front fixing portion and a rear fixing portion, a first mounting assembly, a second mounting assembly, a third mounting assembly and a fourth mounting assembly are provided on the side beam between the front fixing portion and the rear fixing portion, the first mounting assembly is connected to the second mounting assembly, the third mounting assembly is located above the drive shaft hole, and the fourth mounting assembly is located below the drive shaft hole and close to the rear fixing portion; the process comprises the following steps: S1, sand core making Determine the size of the sand core according to the design size of the rear subframe and make the corresponding sand core; S2. Melting and degassing a. Prepare aluminum alloy and heat it in a melting furnace to melt it; b. Then adjust the temperature of the aluminum liquid to 750℃~780℃ for modification; c. Then adjust the temperature of the aluminum liquid to 700℃~730℃ for refining treatment; d. Finally, skim the slag and transfer the aluminum alloy liquid into the holding furnace of the low-pressure casting machine. Adjust the temperature of the aluminum alloy liquid to 680℃~700℃ for pouring. At the same time, remove the waste gas generated during the smelting process. S3, low pressure casting a. Set the low-pressure casting process parameters: the liquid rising pressure is 0.03-0.05 MPa, the liquid rising rate is 30-60 mm / s, the filling pressure is 0.06-0.08 MPa, the filling rate is 50-70 mm / s, the holding pressure is 0.12-0.16 MPa, the holding time is 15-30 seconds, and the pressure is released; b. Complete the entire pouring process of liquid raising, mold filling, pressure holding, and pressure relief, open the mold, and take out the casting; S4, Fluorescent flaw detection a. First, the rear subframe casting is suspended on the clamping mechanism in sequence. The touch screen on the box controls the driving mechanism to move the lifting mechanism, lowering the rear subframe casting into the cleaning tank of the box. The cleaning tank is equipped with a heating plate and a brush connected to a servo motor. The servo motor drives the brush to rotate and remove oil and rust spots on the surface of the rear subframe casting. b. Then, the clamping mechanism is driven to rise by the lifting mechanism. During the rising process, the hot air drying mechanism is activated to evaporate the moisture on the surface of the rear subframe casting; c. The driving mechanism then drives the lifting mechanism to move horizontally, causing the clamping mechanism to move the rear subframe casting to the top of the immersion tank in the box. The rear subframe casting is lowered into the immersion tank via the lifting mechanism and the clamping mechanism, and is immersed in the fluorescent liquid. d. After the soaking is completed, the clamping mechanism is driven to rise by the lifting mechanism. During the rising process, the hot air drying mechanism is activated. The fluorescent liquid on the surface of the rear subframe casting is first washed through the water outlet on the hot air drying mechanism. Then, the developer is sprayed on the surface of the rear subframe casting by the hot air drying mechanism and low-temperature drying is performed. e. Finally, the driving mechanism drives the lifting mechanism to move horizontally, so that the clamping mechanism drives the rear subframe casting to move into the fluorescent flaw detection tank of the box. The fluorescent flaw detection lamp and camera are turned on, and the fluorescence emitted by the fluorescent liquid is displayed on the touch screen through the camera; The clamping mechanism includes a horizontal rod, a vertical column is provided parallel to the bottom of the horizontal rod, a first guide slot is provided on the vertical column, a lifting rod is movably connected between two adjacent vertical columns, the lifting rod is connected to the vertical column through a first fastener, a second guide slot is provided on the lifting rod, and a second fastener is connected to the second guide slot; The hot air drying mechanism includes a hot air box and a blowing plate, the blowing plate is connected to the hot air box through a pipe, the blowing plate is provided with an inclined surface, the inclined surface is provided with an air outlet and a water outlet, and the water outlet is connected to an external water pipe; S5. Heat treatment a. Place the rear subframe casting in an aluminum alloy solution treatment device, heat it to 550°C, keep it warm for 5 to 8 hours, and then place it in water within 1 minute. The water temperature should be controlled at 80°C. b. Cool the solution-treated rear subframe casting to room temperature and keep it at room temperature for 5 hours; c. Transfer to aluminum alloy aging treatment equipment, aging temperature is 150℃~180℃, holding time is 5~8h, take out and air cool; S6. Polishing The heat-treated rear subframe casting is polished by a polishing machine; S7, X-ray detection The polished rear subframe casting is inspected using low-energy X-rays using an X-ray detector; S8, cleaning and drying The qualified rear subframes are cleaned, dried and packed.

2. The method for casting an integrated rear subframe according to claim 1, characterized in that: The interiors of the front cross beam, the rear cross beam and the side beams are all hollow structures.

3. The method for casting an integrated rear subframe according to claim 1, wherein: Through holes are provided inside the front fixing portion and the rear fixing portion, and reinforcing ribs are provided on the outer sides of the front fixing portion and the rear fixing portion.

4. The method for casting an integrated rear subframe according to claim 1, wherein: The first mounting assembly includes two first mounting plates arranged parallel to each other. The first mounting plates are provided with first fixing holes. The first mounting plates are close to the front fixing portion.

5. The method for casting an integrated rear subframe according to claim 4, characterized in that: The second mounting assembly includes two second mounting plates arranged parallel to each other. The second mounting plates are provided with second fixing holes. The second mounting plates are connected to the first mounting plate and are located below the first mounting plate.

6. The method for casting an integrated rear subframe according to claim 1, wherein: The third mounting assembly includes two third mounting plates arranged parallel to each other, and the third mounting plates are provided with third fixing holes.

7. The method for casting an integrated rear subframe according to claim 1, characterized in that: The fourth mounting assembly includes two fourth mounting plates arranged parallel to each other, and the fourth mounting plates are provided with fourth fixing holes.

8. The method for casting an integrated rear subframe according to claim 1, wherein: The driving mechanism in step S4 process a includes a first motor, a first screw and a baffle, the first motor and the baffle are arranged on the side of the box, the first motor is connected to the baffle through a first screw, and the lifting mechanism is connected to the first screw.

9. The method for casting an integrated rear subframe according to claim 8, characterized in that: The lifting mechanism in step S4 process a includes a lower bottom plate, an upper top plate, a movable plate, a slider and a booster block, the slider is connected to the lower bottom plate, a guide rail is provided on the side of the box body, the slider is connected to the guide rail, the booster block is provided at the bottom of the slider, the booster block is connected to the first screw, the upper top plate is fixedly connected to the lower bottom plate through a guide rod, the movable plate is slidably connected to the guide rod, the lower bottom plate is provided with a second motor, the second motor is connected to a second screw, and the second screw passes through the movable plate and is connected to the upper top plate.

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