Integrated lower body dual-ram pressure casting process

Abstract

The application belongs to the technical field of high-pressure die casting production of lower vehicle body, and particularly relates to an integrated lower vehicle body double-pressure injection die casting process, which realizes rapid forming production of the lower vehicle body through cooperation of two pressure injection systems and a die casting die module with a double pouring system. The integrated forming of the lower vehicle body can be realized at one time through the die casting process, and the production efficiency of the lower vehicle body is greatly improved. Meanwhile, the die casting machine has two independent pressure injection systems which cooperate with a double-pressure injection position pouring system. The integrated lower vehicle body is filled symmetrically, the pouring efficiency of the lower vehicle body is ensured, and the uniformity of the mixed aluminum liquid is ensured through counter-attack of the two pouring systems.

Description

Technical Field

[0001] This invention relates to the field of high-pressure die casting production technology for lower body vehicles, specifically disclosing an integrated dual-injection die casting process for lower body vehicles. Background Technology

[0002] High vacuum die casting refers to a casting method in which molten metal alloy is poured into a pressure chamber under high vacuum conditions in the mold cavity, rapidly filling the steel mold cavity and solidifying quickly to form a casting.

[0003] Among them, die casting machine, die casting alloy and die casting mold are the three essential elements of production, and none of them can be omitted. The so-called die casting process is to organically and rationally utilize these three elements to stably, rhythmically and efficiently produce high-quality castings with good appearance, internal quality and dimensional performance that meet the specified requirements.

[0004] Currently, vehicle OEMs or die casting plants use a single injection system to produce castings, as disclosed in patent: 201922355320.X - A mold gating system for die casting automotive parts.

[0005] As the requirements for vehicle body integration become increasingly stringent and the projected area of ​​parts become larger, the limitations of existing die-casting processes mean that single injection systems cannot meet the production needs of large castings, and the performance of the far-end areas of castings cannot meet practical requirements.

[0006] Therefore, in order to solve or improve at least one of the above problems, it is necessary to optimize the design of existing die-casting equipment or processes. Summary of the Invention

[0007] The purpose of this invention is to provide a dual-injection die-casting process that can improve the production efficiency of lower body vehicles.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A one-piece underbody dual-injection die-casting process includes the following steps:

[0010] Step 1: Select a die-casting mold; the die-casting mold has a gating system;

[0011] The gating system includes a gating cavity; gating systems connected to the gating cavity are symmetrically distributed on both sides of the gating cavity;

[0012] The gating system includes an external gating gate, a runner, and an internal gating gate; the external gating gate is connected to the internal gating gate via the runner; the internal gating gate is connected to the gating cavity.

[0013] Step 2: Perform a spot check on the die-casting machine;

[0014] Step 3: Spray an isolation layer inside the die-casting mold cavity;

[0015] Step 4: The casting liquid enters the corresponding barrel of the die-casting machine; the die-casting machine includes two independent injection systems; the casting liquid is injected into the gating system by the injection system;

[0016] Step 5: Die-casting mold closing: After the molten liquid fills the die-casting mold cavity, it is die-cast into one piece by the die-casting machine. After the part cools, it is removed by the part removal robot, and one part is produced. If a new part needs to be produced, the next cycle can be started.

[0017] In step 4, the casting liquid is kept warm in a heat-preserving furnace before being poured into the die-casting mold; each casting system is connected to a heat-preserving furnace.

[0018] The weight difference of the casting liquid in the two insulation furnaces shall not exceed 1%; the temperature difference of the casting liquid in the two insulation furnaces shall not exceed 3℃.

[0019] In step 3, the isolation layer is applied to the mold using a pulsed micro-spraying method.

[0020] In step 4, the two injection systems are required to inject the casting liquid in the corresponding barrels synchronously.

[0021] Each ingate includes multiple individual ingates; the individual ingates in each ingate are distributed sequentially along the X-axis direction of the lower body on the side of the lower body; the ingate is a follow-up ingate.

[0022] The gating system includes a main gating system and two branch gating systems; the main gating system is connected to the corresponding ingates through the two branch gating systems.

[0023] The cross-sectional area of ​​the gating system gradually decreases from the outer gating gate to the corresponding inner gating gate.

[0024] The central region of the gating cavity forms a confluence area;

[0025] In the gating system, the liquid entering the gating system is counteracted in the confluence area.

[0026] The gating and drainage system also includes a slag bag located in the middle region of the gating and drainage cavity; the total volume of the slag bag is V1; the volume of the confluence area is V2; and V1 is required to be no less than V2.

[0027] The liquid inlet speed of the individual units connected in the same area of ​​the lower body is the same.

[0028] The gating system is arranged longitudinally, and the gating system in the gating system pre-fills the liquid through the wheel arches of the lower body.

[0029] The advantages of this invention are as follows:

[0030] This invention discloses a dual-injection die-casting process for an integrated lower body.

[0031] This invention utilizes a dual-injection die-casting process for the integrated lower body, primarily a high-pressure die-casting process.

[0032] By implementing the above-mentioned die-casting process, the present invention can achieve one-piece molding of the lower body in one go, which greatly accelerates the production efficiency of the lower body.

[0033] Meanwhile, the die-casting machine of this invention has two independent injection systems that work together with a dual-injection gating system; this allows for symmetrical filling of the integrated lower body; it not only ensures the casting efficiency of the lower body, but also ensures the uniformity of aluminum molten mixing by counteracting the injection of aluminum molten material by the two gating systems.

[0034] At the same time, by introducing liquid into the lower wheel arches, the risk of cracking at the SPR connection is greatly reduced. Attached Figure Description

[0035] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0036] Figure 1 This is a process flow diagram of the present invention.

[0037] Figure 2 This is a schematic diagram of the structure of the material cylinder connected to the double injection template of the present invention.

[0038] Figure 3 This is a schematic diagram of the structure of the die-casting mold connected to the injection molding machine in this invention.

[0039] Figure 4 This is a curve diagram of dual-injection die casting in this invention.

[0040] Figure 5 This is a schematic diagram of the structure of the die-casting machine connected to the heat-holding furnace in this invention.

[0041] Figure 6 This is the first isometric view of the gating and drainage system in this invention.

[0042] Figure 7 This is the second isometric view of the gating and drainage system in this invention.

[0043] Figure 8 This is a top view of the gating and drainage system in this invention.

[0044] The markings in the above figures are all:

[0045] 1-1. Die casting machine; 1-2. Holding furnace; 1. Gating system; 11. External gate; 12. Sprue; 13. Internal gate. Detailed Implementation

[0046] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0047] A one-piece underbody dual-injection die-casting process includes the following steps:

[0048] Step 1: Select a die-casting mold; the die-casting mold has a gating system 1;

[0049] The gating system 1 includes a gating cavity 14; gating systems 101 connected to the gating cavity 14 are symmetrically distributed on both sides of the gating cavity 14.

[0050] The gating system 101 includes an outer gate 11, a runner 12, and an inner gate 13; the outer gate 11 is connected to the inner gate 13 through the runner 12; the inner gate 13 is connected to the gating cavity 14.

[0051] Step 2: Perform a spot check on die-casting machine 1-1;

[0052] Step 3: Spray an isolation layer inside the die-casting mold cavity;

[0053] Step 4: The casting liquid enters the corresponding barrel of the die casting machine 1-1; the die casting machine 1-1 includes two independent injection systems; the casting liquid is injected into the gating system 1 by the injection system;

[0054] Step 5: Die casting mold closing: After the casting liquid fills the die casting mold cavity, it is die cast into one piece by die casting machine 1-1. After the part cools, it is taken out by the part removal robot, and one part is produced. If a new part needs to be produced, the next cycle can be started.

[0055] This invention utilizes a dual-injection die-casting process for the integrated lower body, primarily a high-pressure die-casting process.

[0056] In this invention, the casting liquid is generally molten aluminum.

[0057] By implementing the above-mentioned die-casting process, the present invention can achieve one-piece molding of the lower body in one go, which greatly accelerates the production efficiency of the lower body.

[0058] Meanwhile, the die-casting machine 1-1 of the present invention has two independent injection systems that work together with the dual injection position gating system 1; this can form a symmetrical filling of the integrated lower body; it can not only ensure the casting efficiency of the lower body, but also ensure the uniformity of aluminum liquid mixing by the anti-impact of the aluminum liquid injected by the two gating systems 101.

[0059] At the same time, by introducing liquid into the lower wheel arches, the risk of cracking at the SPR connection is greatly reduced.

[0060] The specific process steps in this invention are as follows:

[0061] S1: Select a die-casting mold and install the barrel onto the fixed mold template. Because this invention is a dual-injection die-casting, it has two barrels, which are respectively connected to two gating systems 101.

[0062] Specifically, the fixed mold is installed onto the moving and fixed templates of die-casting machine 1-1; the moving and fixed templates need to be installed on a press with dual injection capability;

[0063] The gating system 1 of this invention includes a gating cavity 14; symmetrically distributed on both sides of the gating cavity 14 are gating systems 101 connected to the gating cavity 14; the gating system 101 includes an outer gate 11, a runner 12, and an inner gate 13; the outer gate 11 is connected to the inner gate 13 through the runner 12; the inner gate 13 is connected to the gating cavity 14.

[0064] The gating system 1 disclosed in this invention includes an external gating gate 11, which mainly consists of two sprues. The thickness of the sprues is about 40±5mm and the diameter is ≥280mm. This size can greatly improve the gating ratio of the gating system 1 and increase the thickness of the internal gating gate 13 during die casting, and can also prevent the sprues from bursting during the production process.

[0065] Runner 12: The horizontal runner 12 moves upward in the opposite direction of gravity, and its cross-sectional area gradually decreases. The runner 12 includes a main runner 121 and branch runners 122. The main runner 121 is then divided into two branch runners 122. The cross-sectional area of ​​the two branch runners 122 also gradually decreases, so as to improve the acceleration effect of the aluminum liquid in the runner. The branch runners are connected to 10 individual ingates 131.

[0066] In subsequent use, the molten aluminum preferentially enters the edge of the wheel arch flange, forming a preferential filling of the wheel arch edge. Compared with the traditional center injection and single-sided injection wheel arch, the filling end becomes the filling start position, thereby reducing the risk of insufficient filling. In addition, the wheel arch edge is close to the gate, which can obtain sufficient pressurization capacity, and the microstructure of the wheel arch edge is higher. This can reduce the risk of defects in the wheel arch edge of the product, thereby improving the mechanical properties of the product. Then, the molten aluminum enters the lower body from the wheel arch edge of the lower body, filling the one-piece lower body, and the filling distance is also close.

[0067] In addition, the traditional one-piece underbody casting method is limited by the center casting, which allows for a small area of ​​gating gate, with the area of ​​the inner gating gate typically ≤5000mm². 2The relatively small aluminum flow rate increases the overall filling time of the product, requiring a filling time of ≤120ms. During the filling process, the aluminum temperature drops significantly, making the product prone to defects such as cold runners and flow marks. Using a double-gating system (12 runners) increases the area of ​​the ingate (13), resulting in an overall ingate area of ​​≤9000mm². 2 The aluminum liquid flow rate is about twice that of the original product, the overall filling time of the product is ≤70ms, the temperature drop of the aluminum liquid during the filling process is small, and the risk of defects such as cold flow marks in the product is greatly reduced.

[0068] Slag Bundle 16: Slag Bundle 16 is located in the middle of the product, at the point where the molten aluminum converges. The volume of Slag Bundle 16 is about 5%-8% of the total weight of the product. It can effectively collect the cold material at the end of the product where the aluminum temperature drops and the product temperature is relatively low.

[0069] The inner gate 13 is a conformal inner gate 13. The dual-injection inner gate 13 is designed in a completely conformal manner. The entire gate is arranged according to the shape of the two sides of the lower body. This not only greatly increases the overall filling area of ​​the product, but also directly fills the product edge, effectively improving the mechanical properties such as the elongation rate of the wheel cover, especially the elongation rate. The higher the elongation rate, the lower the risk of SPR cracking, thereby greatly improving the pass rate of SPR connection.

[0070] S2: Perform a spot check on die casting machine 1-1 to ensure that the equipment is in normal working condition; preset 10 injection positions and speeds, select the pressure boosting trigger position, cooling time, core pulling action sequence and speed, product ejection position and ejection force, mold opening and closing action position, punch lubrication position and lubrication amount, and start the equipment, monitor the injection curve, and adjust and optimize the above process parameters in real time. Compared with the traditional single injection curve, the control system needs to adjust two sets of injection systems.

[0071] S3: The mold surface is sprayed with a micro-spraying method to create a uniform isolation layer on the mold surface, which facilitates subsequent demolding.

[0072] S4: The molten aluminum is poured into the barrel through the machine-side heat preservation furnace 1-2. The die casting machine 1-1 consists of two independent injection systems. The injection system follows the master-slave control mode. After the molten aluminum enters the injection barrel, it is injected synchronously. The injection synchronization is ≤20ms.

[0073] S5: The mold is closed. After the aluminum liquid fills the cavity, it is die-cast into one piece by the die-casting machine 1-1. The part is cooled and removed by the part removal robot to start the next cycle.

[0074] S6: This invention relates to two machine-side holding furnaces 1-2, where the weight of the molten aluminum is controlled by a liquid level sensor on the furnace body, such as... Figure 6As shown, after the injection command is issued, by controlling the pressure and time of the liquid pump, the weight difference of the aluminum liquid in the two machine-side holding furnaces 1-2 needs to be guaranteed to be ±1%, and the temperature of the two aluminum liquid streams needs to be ≤3℃.

[0075] Furthermore, in step 4 of this invention, the molten liquid is kept warm in a heat-insulating furnace 1-2 before being poured into the die-casting mold; each gating system 101 is connected to a heat-insulating furnace 1-2; this setting can ensure the constantness of the molten liquid, and at the same time, in this invention, the weight difference of the molten liquid in the two heat-insulating furnaces 1-2 is not higher than 1%; the temperature difference of the molten liquid in the two heat-insulating furnaces 1-2 is not higher than 3°C; based on this setting, the consistency of the subsequent pouring temperature of the two gating systems 101 can be ensured, avoiding excessive pouring defects caused by excessive temperature difference between the two molten liquids.

[0076] Furthermore, in step 3 of this invention, the isolation layer is applied to the mold using a pulsed micro-spraying method. Pulsed micro-spraying is a high-precision spraying technology that precisely sprays the release agent onto the mold surface using micro-nozzles and low-flow spraying equipment, forming a lubricating isolation film. Compared to traditional continuous spraying methods, this technology significantly reduces the amount of release agent used while improving spraying efficiency and casting quality. Pulsed spraying employs intermittent spraying (spray-stop-spray-stop-spray), which reduces thermal shock to the mold, lowers the temperature gradient and thermal stress, thereby increasing mold life. Micro-spraying technology can increase die-casting production capacity, reduce dilution water and wastewater consumption, extend mold life, and significantly reduce costs.

[0077] Furthermore, in step 4 of this invention, the two injection systems are required to synchronously inject the casting liquid in the corresponding barrels; this can ensure synchronous liquid entry on both sides of the casting cavity 14, which facilitates the formation of counter-current in the middle of the casting cavity 14, which not only facilitates subsequent slag removal, but also helps to ensure the relative speed of the casting liquid on both sides is balanced, and helps to ensure the uniformity of the mixing of the two casting liquids.

[0078] Furthermore, in this invention, the gating system 1 includes a gating cavity 14; symmetrically distributed on both sides of the gating cavity 14 are gating systems 101 connected to the gating cavity 14; the gating system 1 disclosed in this invention is mainly applicable to high-pressure die casting process. By using a double gating system 101, this invention adopts a completely symmetrical gating system 101 to form symmetrical filling of the integrated lower body; not only can the casting efficiency of the lower body be guaranteed, but also the uniformity of aluminum liquid mixing can be guaranteed by the anti-flushing of the two gating systems 101.

[0079] Specifically, the gating system 1 disclosed in this invention mainly includes a gating cavity 14; the gating cavity 14 is used for liquid injection molding of the lower body; at the same time, in this invention, a gating system 101 connected to the gating cavity 14 is symmetrically distributed on both sides of the gating cavity 14; the gating system 101 of this invention is a gating runner 12 system; through the above design, this invention enables the gating system 1 to have two sets of gating runner 12 systems, which can greatly improve the mechanical properties of both ends of the lower body, and the elongation rate is a key factor for the qualified spr connection, thereby greatly improving the qualification rate of the spr connection point of the product.

[0080] Meanwhile, the gating system 101 described in this invention includes an outer gate 11, a gating runner 12, and an inner gate 13; the outer gate 11 is connected to the inner gate 13 through the gating runner 12; the inner gate 13 is connected to the gating cavity 14; the combined use of the outer gate 11, the gating runner 12, and the inner gate 13 enables the aluminum liquid to be fed in, which facilitates the subsequent casting and molding of the lower body.

[0081] Furthermore, in this invention, each of the inner gates 13 includes multiple individual inner gates 131; each individual inner gate 131 in each inner gate 13 is distributed sequentially on the side of the lower body along the X-axis direction of the lower body; based on this arrangement, the lower body can have multiple liquid inlet points in the X-axis direction of the body, which can speed up the punching speed of the gating cavity 14; at the same time, because of the increase in punching speed, the temperature drop of the aluminum liquid is smaller during the subsequent filling process, and the risk of defects such as cold run marks in the product is greatly reduced.

[0082] In addition, in this invention, the ingate 13 is a follow-up ingate 13; the dual-injection ingate 13 of this invention is designed in a completely conformal manner, and the entire gate is arranged according to the shape of the two sides of the lower body, which not only greatly increases the overall filling area of ​​the product, but also directly fills the edge of the product, effectively improving the mechanical properties such as the elongation rate of the wheel cover, especially the elongation rate performance. The higher the elongation rate, the lower the risk of SPR cracking, thereby greatly improving the pass rate of SPR connection.

[0083] Furthermore, in this invention, the gating system 12 includes a main gating system 121 and two branch gating systems 122. The main gating system 121 is connected to the corresponding ingate 13 through the two branch gating systems 122. The main gating system 121 is mainly used to connect to the outer gate 11, and the branch gating systems 122 are distributed along the length of the side of the gating cavity 14. This arrangement can increase the area of ​​the ingate 13 to a certain extent and optimize the liquid inlet speed of the gating cavity 14. At the same time, the use of branch gating systems 122 facilitates the diversion of the aluminum liquid entering from the main gating system 121 and facilitates liquid injection operations at multiple positions of the ingate 13.

[0084] Furthermore, in this invention, the cross-sectional area of ​​the gating system 12 gradually decreases from the outer gate 11 to the corresponding inner gate 13; this setting can accelerate the flow speed of molten aluminum in the gating system 12; optimize the molten aluminum punching speed, ensure that the temperature drop of molten aluminum during the filling process is small, and greatly reduce the risk of defects such as cold run marks in the product.

[0085] Furthermore, the main gating system 121 described in this invention is arranged at an angle during use. The angled arrangement of the main gating system 121 facilitates the flow of molten aluminum within it. Additionally, the connection between the main gating system 121 and the branch gating system 122 in this invention employs an arc-shaped transition surface. This arrangement reduces the excessive running resistance formed at the connection between the main gating system 121 and the branch gating system 122 when the molten aluminum is diverted from the main gating system 121 to the branch gating system 122.

[0086] Furthermore, in this invention, the individual ingate 131 near the connection between the main gating 121 and the branch gating 122 has a flow-limiting bend 132. Because the liquid inflow velocity of the individual ingate 131 near the connection between the main gating 121 and the branch gating 122 is relatively large, in order to reduce the flow velocity of the individual ingate 131 at this location, a flow-limiting bend 132 is set at the individual ingate 131 to reduce the flow velocity within the individual ingate 131. This ensures the consistency of the aluminum liquid entering the gating cavity 14 as much as possible, and avoids excessive differences in the aluminum liquid flow velocity between adjacent individual ingates 131, which could generate eddies and cause casting defects in the subsequent lower body.

[0087] Furthermore, in this invention, the connection between the branch gating 122 and each individual ingate 131 adopts an arc-shaped transition; this setting can reduce the running resistance at the connection between the branch gating 122 and each corresponding individual ingate 131.

[0088] Furthermore, in this invention, a confluence region 102 is formed in the middle region of the gating cavity 14; the liquid entering the gating system 101 is counteracted in the confluence region 102; with this arrangement, during subsequent filling operations, the two streams of molten aluminum provided by the two gating systems 101 impact and counteract each other instantly, generating a large impact energy, effectively causing the two streams of molten aluminum to fuse, reducing defects in the fusion of molten aluminum, and greatly improving the mechanical properties of the product, especially on both sides of the front floor and at the lower wheel arches, thereby greatly reducing the risk of cracking at the spr connection.

[0089] Furthermore, the gating system 1 described in this invention also includes a slag pot 16 disposed in the middle region of the gating cavity 14; the slag pot 16 is located in the middle of the product, at the point where the molten aluminum flows, and the volume of the slag pot 16 is approximately 5%-8% of the total weight of the product, which can effectively collect the cold material at the end of the product where the aluminum temperature drops and the product temperature is relatively low.

[0090] In this invention, the total volume of the slag bag 16 is V1; the volume of the confluence area 102 is V2; V1 is required to be no less than V2; the cold material at the end of the product confluence area 102 volume can be discharged into the slag bag 16 to the maximum extent; even if the confluence area 102 is not in the center of the product, the cold material at the end can be discharged into the slag bag 16; thus optimizing the use effect of the pouring and drainage system 1.

[0091] Furthermore, in this invention, the liquid inlet speed of the individual inlet gates 131 connected in the same area of ​​the lower body is the same. This setting can ensure the consistency of the aluminum liquid entering the gating cavity 14 through the corresponding individual inlet gate 131 in the same area of ​​the lower body, and avoid the aluminum liquid flow rate of the corresponding individual inlet gate 131 in the same area being too different, which would generate eddies in the gating cavity 14 and cause subsequent casting defects in the lower body; thus affecting the high pressure die casting effect of the lower body.

[0092] Furthermore, in this invention, the gating system 1 is arranged longitudinally, and the gating system 101 in the gating system 1 pre-injects liquid through the lower wheel arch of the vehicle body. Based on this design, the molten aluminum can preferentially enter the edge of the wheel arch flange, forming preferential filling of the wheel arch edge. Compared with the traditional center injection and single-sided injection, the wheel arch is changed from the filling end to the filling start position, thereby reducing the risk of insufficient filling. In addition, the wheel arch edge is close to the inner gate 13, which can obtain sufficient pressurization capacity, and the microstructure density of the wheel arch edge is higher. At the same time, the liquid injection through the lower wheel arch of the vehicle body greatly reduces the risk of cracking at the spr connection.

[0093] specific;

[0094] This invention discloses a high-pressure dual-injection gating system 1 for an integrated lower body; the integrated lower body adopts a dual-injection gating system 101, which adopts a completely symmetrical gating system 101 to form symmetrical filling of the integrated lower body. The filling time of the traditional single-sided filling method is ≥100ms, while the filling time of the dual-injection method can be shortened to ≤70ms, which greatly expands the die casting process window and reduces the debugging difficulty for on-site process personnel.

[0095] Furthermore, the entire ingate 13 in the gating system 101 of the present invention is laid out following the outer contour of the lower body. The conformal ingate 13 is arranged to form a completely symmetrical structure, which can greatly shorten the distance from the ingate 13 to the two sides of the lower body. At the same time, after filling, the two streams of aluminum liquid impact and collide instantly, generating a large impact energy, which effectively makes the aluminum liquid fuse, reduces the defects of aluminum liquid fusion, and greatly improves the mechanical properties of the product, especially on both sides of the front floor and the wheel arches of the lower body, thereby greatly reducing the risk of cracking at the spr connection.

[0096] Example 1 is as follows:

[0097] The gating system 1 disclosed in this invention includes an external gating gate 11, which mainly consists of two sprues. The thickness of the sprues is about 40±5mm and the diameter is ≥280mm. This size can greatly improve the gating ratio of the gating system 1 and increase the thickness of the internal gating gate 13 during die casting, and can also prevent the sprues from bursting during the production process.

[0098] Runner 12: The horizontal runner 12 moves upward in the opposite direction of gravity, and its cross-sectional area gradually decreases. The runner 12 includes a main runner 121 and branch runners 122. The main runner 121 is then divided into two branch runners 122. The cross-sectional area of ​​the two branch runners 122 also gradually decreases, so as to improve the acceleration effect of the aluminum liquid in the runner. The branch runners are connected to 10 individual ingates 131.

[0099] In subsequent use, the molten aluminum preferentially enters the edge of the wheel arch flange, forming a preferential filling of the wheel arch edge. Compared with the traditional center injection and single-sided injection wheel arch, the filling end becomes the filling start position, thereby reducing the risk of insufficient filling. In addition, the wheel arch edge is close to the gate, which can obtain sufficient pressurization capacity, and the microstructure of the wheel arch edge is higher. This can reduce the risk of defects in the wheel arch edge of the product, thereby improving the mechanical properties of the product. Then, the molten aluminum enters the lower body from the wheel arch edge of the lower body, filling the one-piece lower body, and the filling distance is also close.

[0100] In addition, the traditional one-piece underbody casting method is limited by the center casting, which allows for a small area of ​​gating gate, with the area of ​​the inner gating gate typically ≤5000mm². 2 The relatively small aluminum flow rate increases the overall filling time of the product, requiring a filling time of ≤120ms. During the filling process, the aluminum temperature drops significantly, making the product prone to defects such as cold runners and flow marks. Using a double-gating system (12 runners) increases the area of ​​the ingate (13), resulting in an overall ingate area of ​​≤9000mm². 2 The aluminum liquid flow rate is about twice that of the original product, the overall filling time of the product is ≤70ms, the temperature drop of the aluminum liquid during the filling process is small, and the risk of defects such as cold flow marks in the product is greatly reduced.

[0101] Slag Bundle 16: Slag Bundle 16 is located in the middle of the product, at the point where the molten aluminum converges. The volume of Slag Bundle 16 is about 5%-8% of the total weight of the product. It can effectively collect the cold material at the end of the product where the aluminum temperature drops and the product temperature is relatively low.

[0102] The inner gate 13 is a conformal inner gate 13. The dual-injection inner gate 13 is designed in a completely conformal manner. The entire gate is arranged according to the shape of the two sides of the lower body. This not only greatly increases the overall filling area of ​​the product, but also directly fills the product edge, effectively improving the mechanical properties such as the elongation rate of the wheel cover, especially the elongation rate. The higher the elongation rate, the lower the risk of SPR cracking, thereby greatly improving the pass rate of SPR connection.

[0103] Meanwhile, in this invention, the product middle confluence area 102 includes the product and the slag bag 16. The total volume of the slag bag 16 is V1, and the volume of the product confluence part is V2. V1≥V2, so that the end cold material of the product confluence part volume can be discharged into the slag bag 16 to the maximum extent. Even if the confluence part is not in the center of the product, the end cold material can be discharged into the slag bag 16.

[0104] The die-casting process disclosed in this invention meets the forming process requirements of die-casting parts with ultra-large projected area and can be used for die-casting of ultra-large integrated vehicle bodies.

[0105] The die-casting machine 1-1 consists of two independent injection systems. The injection systems follow a master-slave control mode to achieve synchronous operation during the aluminum liquid filling process. Based on the product filling time and the fusion zone, a double-gating 12-stage filling and overflow system and a vacuum extraction structure are designed. According to the aluminum liquid requirements of the parts, aluminum liquid of the same weight and temperature is supplied to the two barrels from the two machine-side holding furnaces 1-2. Through synchronous injection by the two injection systems, the aluminum liquid in the two barrels is pushed into the mold cavity at the same speed. The aluminum liquid is solidified and removed by uniform cooling of the mold to obtain a complete part.

[0106] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. An integrated underbody dual- shot die casting process characterized in that; Includes the following steps: Step 1: Select a die-casting mold; the die-casting mold has a gating system; The gating system includes a gating cavity; gating systems connected to the gating cavity are symmetrically distributed on both sides of the gating cavity; The gating system includes an external gating gate, a runner, and an internal gating gate; the external gating gate is connected to the internal gating gate via the runner; the internal gating gate is connected to the gating cavity. Each ingate includes multiple individual ingates; the individual ingates in each ingate are distributed sequentially along the X-axis direction of the lower body on the side of the lower body. The gating system includes a main gating system and two branch gating systems; the main gating system is connected to the corresponding ingate through the two branch gating systems. The cross-sectional area of ​​the gating system gradually decreases from the outer gating gate to the corresponding inner gating gate; The central region of the gating cavity forms a confluence area; In the gating system, the liquid entering the gating system is counteracted in the confluence area; The individual ingate near the connection between the main runner and the branch runner has a flow-limiting corner; Step 2: Perform a spot check on the die-casting machine; Step 3: Spray an isolation layer inside the die-casting mold cavity; Step 4: The casting liquid enters the corresponding barrel of the die-casting machine; the die-casting machine includes two independent injection systems; The molten material is injected into the gating system by the injection system; Step 5: Die-casting mold closing: After the molten liquid fills the die-casting mold cavity, it is die-cast into one piece by the die-casting machine. After the part cools, it is removed by the part removal robot, and one part is produced. If a new part needs to be produced, the next cycle can be started.

2. An integrated underbody bi- injection die casting process as claimed in claim 1, wherein; In step 4, the casting liquid is kept warm in a heat-preserving furnace before being poured into the die-casting mold; each casting system is connected to a heat-preserving furnace.

3. An integrated underbody bi-injection die casting process according to claim 2, wherein; The weight difference of the casting liquid in the two insulation furnaces shall not exceed 1%; the temperature difference of the casting liquid in the two insulation furnaces shall not exceed 3℃.

4. An integrated underbody bi-injection die casting process as claimed in claim 1, wherein; In step 3, the isolation layer is applied to the mold using a pulsed micro-spraying method.

5. An integrated underbody bi-injection die casting process as claimed in claim 1, wherein; In step 4, the two injection systems are required to inject the casting liquid in the corresponding barrels synchronously.

6. An integrated underbody bi-injection die casting process as claimed in claim 1, wherein The ingate is a follow-up ingate.

7. An integrated underbody bi-injection die casting process as claimed in claim 1, wherein, The gating and discharge system also includes a slag bag disposed in the middle region of the gating and discharge cavity; the total volume of the slag bag is V1; The volume of the confluence region is V2; V1 must not be less than V2.

8. An integrated underbody bi- injection die casting process as claimed in claim 6, wherein, The liquid inlet speed of the individual units connected in the same area of ​​the lower body is the same.

9. An integrated underbody bi-vent die-casting process as claimed in claim 6, wherein, The gating system is arranged longitudinally, and the gating system in the gating system pre-fills the liquid through the wheel arches of the lower body.

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