A die-casting mold for an aluminum alloy connecting bracket for new energy vehicles

Abstract

The present invention relates to a die-casting mold, and in particular provides a die-casting mold for an aluminum alloy connecting bracket for new energy vehicles, aiming to solve the problems of uneven filling speed, shrinkage, cold shut and other defects in the initial design of the die-casting mold during the filling process. The optimization measures are as follows: the branch runner and the cross runner of the fastening part close to the rib part are connected by a circular arc transition to reduce the jetting tendency of the molten metal of the branch runner when entering the mold cavity, and prevent negative pressure air suction or air entrapment; increase the cross-sectional area of the branch runner and the inner gate to speed up the filling speed of the rib part and the fastening part; an auxiliary overflow groove is provided in the middle position of the fastening part close to the inner gate to remove the gas near the local position of the inner gate, reduce the generation of air holes, and thus avoid the formation of liquid phase islands at the corners of the fastening part.

Description

Technical Field

[0001] The present invention relates to the field of die-casting dies, and in particular to a die-casting die for an aluminum alloy connecting bracket for a new energy vehicle. Background Art

[0002] The manufacturing process of new energy vehicles often requires connecting the vehicle's electric motor with other power components to improve system efficiency and achieve complex functions. This aluminum alloy connecting bracket component, used for assembling the electric motor and other power components in new energy vehicles, is made of A356.2 aluminum alloy and mass-produced using cold-chamber high-pressure casting. This material has advantages such as good fluidity, low specific gravity, and excellent corrosion resistance. It also exhibits excellent properties such as no tendency to thermal cracking during die-casting, low linear shrinkage, and excellent airtightness. The connecting bracket product weighs 2.75 kg, has a volume of 1013.38 cm³, an average wall thickness of 3.5 mm, and dimensions of 319 mm x 209 mm. The die-casting mold for the connecting bracket component is made of SKA61 grade. To connect the electric motors of new energy vehicles with a variety of differently shaped power components, the inner surface structure of the connecting bracket features numerous uneven frames and thin-walled connecting ribs. This uneven structure results in uneven filling speed and flow rate across various parts during aluminum alloy die-casting, which can easily lead to defects such as air holes, cold shuts, and material shortages, especially in areas requiring machining. The initially designed gating system uses multiple branch runners and ingates of equal cross-sectional area to pour into the casting cavity. Each branch runner intersects the runner perpendicularly, and multiple overflow troughs are provided to stabilize the flow of the molten metal, contain impurities, and enhance air venting.

[0003] MAGMASOFT software was used to simulate the temperature changes, filling speed, air pressure changes and shrinkage defect prediction during the die-casting filling process of the bracket. The results showed that the filling speed was uneven and the filling completion time was asynchronous during the filling process; in the early stage of filling, the heat conduction speed between the aluminum liquid and the mold was asynchronous, and there was a certain difference in the temperature change rate; the air pressure value at the intersection of the fastening part cavity and the rib part cavity was higher, and a small amount of aluminum liquid was entrained at the gate position; liquid phase islands formed hot nodes at the four corners of the fastening part, which would cause shrinkage defects after solidification, and would affect the connection between the motor and other power components after molding. Summary of the Invention

[0004] The present invention aims to solve the above technical problems, optimize and balance the filling flow and speed, so that the filling of the rib cavity, the fastening cavity and the frame cavity can be completed synchronously, and the difference in temperature change rate can be reduced.

[0005] The technical solution adopted by the present invention is a die-casting mold for an aluminum alloy connecting bracket for new energy vehicles, including an upper mold, a lower mold, a pouring system and an overflow system, wherein the upper mold can be separated and buckled relative to the lower mold, and a casting cavity is formed when the upper mold and the lower mold are buckled; the casting cavity includes a rib cavity, a fastening cavity and a frame cavity, and its complexity is that the frame cavity is larger than the fastening cavity and larger than the rib cavity; the pouring system includes a straight runner, a horizontal runner, a branch runner and an inner gate; one end of the straight runner is connected to the gate and the other end is connected to the horizontal runner, and a plurality of branch runners are vertically connected to the horizontal runner, and each branch runner is It is connected to the casting cavity through corresponding inner gates; the number of branch runners connected to the frame cavity is greater than the number of branch runners connected to the fastening cavity, and the number of branch runners connected to the fastening cavity is greater than the number of branch runners connected to the rib cavity; the overflow system includes multiple overflow troughs, which are respectively connected to the casting cavity; the number of overflow troughs connected to the fastening cavity is greater than the number of overflow troughs connected to the frame cavity, and the number of overflow troughs connected to the frame cavity is greater than the number of overflow troughs connected to the rib cavity; the cross-sectional area of the inner gate of the fastening cavity close to the rib cavity is greater than the cross-sectional area of the inner gate of the rib cavity.

[0006] Increasing the cross-sectional area of the ingate near the rib cavity increases the filling flow rate of the rib and fastening cavities, accelerating the filling speed and achieving equilibrium with the filling of the frame cavity. This prevents uneven filling speeds and the confluence of molten aluminum at different speeds and temperatures, which can cause defects such as air entrainment, laminar flow, and flow streaks. In the initial design, the smaller cross-sectional area of the ingate at this location increased the flow rate and pressure, preventing sufficient heat transfer between the molten aluminum and the mold, resulting in asynchrony in the heat transfer rate. Therefore, increasing the cross-sectional area of this ingate can reduce the flow rate and pressure at this ingate, ensuring sufficient heat transfer between the molten aluminum and the mold.

[0007] Furthermore, an oblique connection is provided between the branch runner and the cross runner in the fastening portion cavity close to the rib portion cavity.

[0008] Changing the angle between the runner and the sprue affects the flow velocity and pressure distribution of the molten aluminum in the sprue. Increasing the angle can control the flow velocity of the molten aluminum to a certain extent, reducing the tendency of the molten aluminum to spray when entering the mold cavity, avoiding problems such as turbulence and air holes caused by excessive speed. It also helps maintain appropriate static pressure, ensuring that the molten metal can smoothly fill the mold cavity. The sloping feed of the runner also prevents negative pressure aspiration or air entrapment.

[0009] Furthermore, an auxiliary overflow groove is provided at a middle position of the fastening portion close to the inner gate.

[0010] The thicker wall thickness of the fastening section can easily create localized thermal hotspots in areas with uneven wall thickness. This, combined with ineffective shrinkage compensation from the gating system, reduces the density of the localized crystal structure and leads to shrinkage defects and shrinkage cavities during solidification. Placing an auxiliary overflow trough in the middle of the fastening section near the ingate to remove gas near the ingate can reduce the formation of pores and help resolve the problem of liquid phase islands forming at the corners of the fastening section.

[0011] Furthermore, the inclination angle between the runner and the cross runner of the fastening portion cavity close to the rib portion cavity is 110° to 165°.

[0012] The purpose of setting the runner at an angled intersection with the runner is to control the flow velocity of the molten aluminum, reduce the tendency of the molten aluminum to spray when entering the mold cavity, avoid problems such as turbulence and air holes caused by excessive speed, and prevent negative pressure aspiration or air entrapment. If the angle is less than 110°, this effect will not be achieved. If the angle is greater than 165°, the molten metal may encounter more resistance during flow, reducing fluidity and preventing the molten aluminum from filling the mold cavity smoothly. This may cause defects such as underfill or cold shut in the casting. In addition, if the angle is too large, it may affect the flow of the molten metal in the runner, thereby affecting the temperature distribution, resulting in inconsistent cooling rates in different parts of the casting, causing stress concentration, and even leading to crack formation.

[0013] Furthermore, the inner gate is in a flat bell-mouth shape.

[0014] The flat bell-shaped ingate design can reduce temperature differences to a certain extent, which is beneficial for preventing cracks near the ingate. In addition, the flat bell-shaped shape helps reduce fluid turbulence and improve filling consistency, which is critical to ensuring casting quality.

[0015] Furthermore, the number of branch runners connected to the rib portion is 1 to 2, the number of branch runners connected to the fastening portion is 2 to 4, and the number of branch runners connected to the frame portion is 3 to 5.

[0016] Because the complexity of the frame part of the target casting is greater than that of the fastening part, and the complexity of the fastening part is greater than that of the rib part, the frame part has the largest number of branch runners, followed by the fastening part, and the least is the rib part. Combined with the design parameters such as cavity filling time, gate cross-sectional area, and filling pressure, the number of branch runners connected to the rib part is set to 1-2, the number of branch runners connected to the fastening part is 2-4, and the number of branch runners connected to the frame part is 3-5, so that the filling speeds of the rib part, fastening part, and frame part are balanced and the filling completion time can be synchronized.

[0017] Furthermore, the number of overflow grooves connected to the rib portion is 1 to 2, the number of overflow grooves connected to the fastening portion is 4 to 6, and the number of overflow grooves connected to the frame portion is 3 to 5.

[0018] The rib part is a thin-walled frame connecting rib, and the required aluminum liquid flow is relatively small, so 1 to 2 overflow grooves can meet the requirements; the frame part has a more complex structure, but its wall thickness is relatively uniform, so 3 to 5 overflow grooves are set; for the fastening part, although its structure is not as complex as the frame part, its wall thickness is uneven, and the thickness of the part connected to the rib part and the frame part is larger, which is prone to shrinkage holes and shrinkage defects during solidification. The fastening part needs to be machined after die-casting, and has high requirements on the part dimensional accuracy and internal structure density. Therefore, 4 to 6 overflow grooves are set in the fastening part to stabilize the flow state of the molten metal, and to accommodate impurities and improve the exhaust effect, thereby improving the die-casting quality of this part.

[0019] Furthermore, the rib portion cavity has a thin-walled portion, and an overflow groove is connected to the thin-walled portion.

[0020] Due to the narrow cavity in the thin-walled area, the phenomenon of "air trapped in dead corners" may occur due to poor filling during filling. Therefore, an overflow groove is set here to avoid this situation.

[0021] Furthermore, the overflow trough includes a main body, a connecting part and an exhaust channel. The connecting part connects the main body with the casting cavity. One end of the exhaust channel is connected to the main body, and the other end passes through the upper mold.

[0022] The condensed molten metal at the front of the injection cavity and the gas entrained by the molten metal during the filling process enter the main body of the overflow trough through the connecting part, maintaining the flow of the molten aluminum and ensuring that the molten metal can smoothly fill the cavity. The main body contains the condensed molten metal, while the gas is discharged from the mold through the exhaust channel.

[0023] Furthermore, the rib cavity is a thin-walled frame connecting rib, the fastening cavity has a thicker wall thickness, the frame cavity has a relatively uniform wall thickness, and the thickness of the rib cavity and the fastening cavity is greater than the thickness of the frame cavity.

[0024] The structural characteristics of the casting cavity have a crucial impact on mold design. The thin-walled structure of the rib cavity results in a low aluminum flow rate during filling, which is prone to defects such as jetting, air entrainment, and cold shuts. Balanced filling pressure and a properly designed overflow channel are essential. The thicker walls of the fastening cavity prevent heat dissipation and prevent effective shrinkage compensation, potentially leading to a decrease in the density of the localized crystal structure and the formation of shrinkage defects and shrinkage cavities during solidification. Therefore, it is necessary to adjust the filling speed and pressure to achieve a more uniform pouring and reduce the formation of liquid phase islands, or to add a ventilation system to reduce the formation of air holes to avoid the formation of liquid phase islands. The frame cavity has a more uniform wall thickness, thinner than the fastening and rib cavities, resulting in faster solidification. However, due to the difference in filling flow and speed, defects such as air holes, cold shuts, and deformation are prone to occur at the local intersection of the frame and solid cavities, affecting dimensional accuracy and ultimately the realization of the connection and installation function. Therefore, it is necessary to balance the filling speed and pressure of the frame cavity, the fastening cavity, and the rib cavity.

[0025] Compared with the prior art, the present invention has the following beneficial effects: by increasing the cross-sectional area of the ingates near the rib cavity of the fastening portion, the filling flow rates of the rib and fastening cavities are increased, and the filling speed is accelerated, achieving equilibrium with the filling of the frame cavity. This reduces defects such as air entrainment, laminar flow, and flow lines caused by the convergence of molten aluminum at different speeds and temperatures due to uneven filling speeds. Furthermore, increasing the cross-sectional area of the ingates reduces the flow rate and air pressure at the ingates, allowing for sufficient heat exchange between the molten aluminum and the mold. This resolves issues such as asynchronous heat conduction between the molten aluminum and the mold, differences in temperature change rates, and uneven temperature gradients in different areas during the filling process. Accelerating the filling speed of the ingates also allows the molten aluminum to evenly fill the cavity, reducing the occurrence of air holes and defects in the fastening portion, and playing a role in preventing the formation of liquid phase islands in the fastening portion cavity. Changing the gate in the fastening cavity near the rib cavity to an inclined feed design reduces the tendency of molten metal to spurt when entering the cavity, lengthens the stroke, and prevents negative pressure aspiration and air entrapment. An auxiliary overflow trough is installed in the center of the fastening cavity near the gate to reduce the formation of air holes in the corners of the fastening area, thereby avoiding the formation of liquid phase islands in this area. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a three-dimensional diagram of the aluminum alloy connecting bracket.

[0027] Figure 2(a) is a schematic diagram of the initial design cavity, pouring system, and overflow system.

[0028] Figure 2(b) is a schematic diagram of the structure of the initial design cavity.

[0029] Figure 2(c) is a schematic diagram of the structure of the initial design connecting bracket casting system.

[0030] Figure 3(a) is a simulation diagram of the aluminum liquid filling 20%.

[0031] Figure 3(b) is a simulation diagram of the aluminum liquid filling 60%.

[0032] Figure 3(c) is a simulation diagram of the aluminum liquid filling 85%.

[0033] Figure 3(d) is a simulation diagram of 95% aluminum liquid filling.

[0034] Figure 4(a) is a simulation diagram of the air pressure change and air entrapment defects during the filling process.

[0035] Figure 4(b) is a simulation diagram for the prediction of thermal shrinkage defects.

[0036] Figure 5 This is a three-dimensional view of the upper mold.

[0037] Figure 6 This is a three-dimensional diagram of the lower mold.

[0038] Figure 7 Schematic diagram of the connection between the optimized cavity, gating system and overflow system.

[0039] Figure 8 Schematic diagram of the optimized cavity structure.

[0040] Figure 9 Schematic diagram of the optimized gating system.

[0041] Figure 10 PQ generated by simulation after modification of the second ingate cross-sectional area 2 Relationship curve.

[0042] Figure 11(a) shows the simulation of the gas pressure at the intersection of the metal liquid before optimization.

[0043] Figure 11(b) shows the simulation of the gas pressure at the intersection of metal and liquid after optimization.

[0044] Figure 12 This is a simulation diagram of the temperature changes of the molten metal and mold during the filling process. DETAILED DESCRIPTION

[0045] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present invention. To better illustrate the following embodiments, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent actual product dimensions. Those skilled in the art will appreciate that some well-known structures and their descriptions may be omitted from the accompanying drawings.

[0046] like Figure 1As shown, the target casting is an aluminum alloy connecting bracket 1 for new energy vehicles, including a rib portion 11, a fastening portion 12 and a frame portion 13. The rib portion 11 is a thin-walled frame connecting rib. During die-casting, the molten metal flow rate is relatively small, which is prone to defects such as jetting, air entrainment and cold shut. It is necessary to balance the filling pressure and reasonably set the overflow groove. The fastening portion 12 is a connecting and fastening assembly part that connects other parts. After die-casting, it is necessary to perform machining. Therefore, the dimensional accuracy and internal structure density of the parts in this part are relatively high. The internal structure of the casting must be dense and free of pores. The wall thickness of the frame portion 13 is relatively uniform and easy to solidify quickly. However, due to the difference in filling flow rate and speed, the local position where it intersects with the solid portion is prone to defects such as pores, cold shut and deformation. The thickness of the rib portion 11 and the fastening portion 12 is greater than that of the frame portion 13.

[0047] According to the structural characteristics and quality requirements of the target casting, and based on the selected die-casting machine parameters such as pressure, speed and barrel diameter, a preliminary pouring system, overflow system and mold preheating temperature were designed. The process parameters are shown in Table 1.

[0048] Table 1 Initial parameters of the numerical simulation of low-pressure casting of bracket

[0049] Parameter name Numerical Parameter name Numerical Die casting machine tonnage 800t Cavity filling time 0.032s Casting pressure 650bar Gate speed 56m / s Injection stroke 530mm Initial mold temperature 185° Minimum punch speed 0.2m / s Ingate cross-sectional area adjustment range <![CDATA[2.0cm 2 -5.5cm 2 ]]> Punch maximum speed 3.5m / s Aluminum liquid temperature 660° Punch diameter 50mm Maximum filling pressure 63.5Mpa

[0050] Based on the principle that the ingates should be positioned to minimize the flow of molten metal into the mold cavity, preventing excessive heat loss during the filling process and the resulting die-casting defects such as cold shuts or patterns, the initial ingates were designed using multiple, relatively short, branch runners, as shown in Figure 2(a). Each branch runner had similar cross-sectional shapes and dimensions, ensuring balanced and smooth filling of the molten metal, facilitating venting and transferring static pressure. Furthermore, given the flat, dispersed shape of the connecting bracket, the differentiated structures of the ribs, fasteners, and frame could hinder balanced filling of the molten aluminum. During filling, the intersection of the several molten metal streams could also generate vortices and air entrainment due to collisions. Furthermore, the varying solidification sequences caused by uneven wall thickness could also cause die-casting defects such as cold shuts and deformation. Therefore, multiple overflow troughs were designed to stabilize the molten metal flow, contain impurities, and enhance venting. A dedicated overflow trough was also incorporated to address the thin-walled ribs and prevent "dead corner air trapping" caused by poor filling.

[0051] As shown in Figures 2(a), 2(b) and 2c, a die-casting mold for an aluminum alloy connecting bracket for new energy vehicles includes an upper mold 6, a lower mold 7, a pouring system 3 and an overflow system 4. The upper mold 6 can be engaged and separated relative to the lower mold 7. When the upper mold 6 and the lower mold 7 are engaged, the upper mold 6 and the lower mold 7 can form a casting cavity 2.

[0052] The casting cavity 2 includes a rib cavity 21 , a fastening cavity 22 and a frame cavity 23 .

[0053] The pouring system 3 includes a sprue 31, a runner 32, a branch runner 33, and an ingate 34. One end of the sprue 31 is connected to the main gate, and the other end is connected to a first runner 321 and a second runner 322. The first runner 321 and the second runner 322 are located on either side of the sprue 31. The first runner 321 is sequentially connected to a first branch runner 331, a second runner 332a, and a third runner 333. The second runner 322 is sequentially connected to a fourth runner 334, a fifth runner 335, and a sixth runner 336. The first branch runner 331, the second runner 332a, the third runner 333, the fourth runner 334, the fifth runner 335, and the sixth runner 336 intersect perpendicularly with the first runner 321 and the second runner 322, respectively. The cross-sectional shapes and sizes of the first branch runner 331, the second branch runner 332a, the third branch runner 333, the fourth branch runner 334, the fifth branch runner 335 and the sixth branch runner are similar. The first branch runner 331 is connected to the rib cavity 21 through the first inner gate 341, the second branch runner 332a and the third branch runner 333 are connected to the fastening cavity 22 through the second inner gate 342a and the third inner gate 343 respectively, the fourth branch runner 334, the fifth branch runner 335 and the sixth branch runner 336 are connected to the frame cavity 23 through the fourth inner gate 344, the fifth inner gate 345 and the sixth inner gate 346 respectively, and the cross-sectional area of the first inner gate 341, the second inner gate 342a and the sixth inner gate 343 is 2.25 cm 2 The cross-sectional area of the third ingates 343, the fourth ingates 344 and the fifth ingates 345 is 3.35 cm 2 .

[0054] The overflow system includes multiple overflow grooves 4, which are respectively connected to the casting cavity 2. Among them, there is one overflow groove 4 connected to the rib cavity 21, which is arranged at the thin-wall position of the rib cavity 21. There are four overflow grooves 4 connected to the fastening cavity 22, and there are three overflow grooves 4 connected to the frame cavity 23.

[0055] According to the die-casting structural characteristics and quality requirements of the connecting bracket parts, MAGMASOFT software was used to simulate the temperature change, filling speed, air pressure change and shrinkage defect prediction of the bracket die-casting filling process.

[0056] like Figure 3(a) 、 3(b)Figures 3(c), 3(d) and 3(e) show simulations of the various stages of molten aluminum filling. Comparisons of these simulations reveal uneven filling rates and cooling and solidification sequences across various process zones during the solidification process of the bracket casting. The temperature change simulation results show that during the initial filling phase of the molten aluminum (Figure 3(a)), the heat transfer rate between the molten aluminum and the mold is asynchronous, resulting in varying temperature change rates. As shown in Figure 3(b), the filling completion times of the rib, fastener, and frame cavities are not synchronized. When the frame cavity, which is completed first, is nearly full, the rib and fastener cavities are still nearly one-fifth full. The simulation results in Figures 3(c) and 3(d) show that air trapping occurs near the rib cavity in the fastener cavity. Furthermore, the temperature gradient distribution across various regions during the filling process is highly uneven, making shrinkage, cavities, and cold shut defects more likely to occur. This may be due to the uneven filling rates, which cause the molten aluminum in different zones to cool at different rates, resulting in varying temperature gradients.

[0057] For the situation shown in Figure 3(a), the cross-sectional area of the gate at that location and the angle between the branch runner and the cross runner can be increased to reduce the aluminum liquid flow rate of the branch runner and the gate, so that the heat conduction between the aluminum liquid and the mold can be fully exchanged. For the situations shown in Figures 3(b), 3(c) and 3(d), it is also necessary to increase the cross-sectional area of the gate at the corresponding location, increase the filling flow rate and filling speed, so that the filling flow rate and speed of the rib cavity, the fastening cavity and the frame cavity are balanced. For the situation where the temperature gradient distribution in different areas of the filling process is uneven, the cross-sectional area of the gate at the corresponding location can be increased and the filling speed at the corresponding location can be adjusted so that the aluminum liquid in each part of the casting cavity can fill the mold evenly, thereby reducing the formation of temperature gradients.

[0058] The air pressure simulation shown in Figure 4(a) shows that the air pressure value is higher at the intersection of the rib part and the fastening part. There is air pocket in the machined area of the fastening part, and internal air holes may appear after machining. At the same time, there is also a small amount of air pocket in the molten aluminum at the gate position.

[0059] The reason is that the feed flow and speed of the six ingates are uneven. When the molten aluminum from different ingates converges at different speeds and temperatures at the final filling point of the casting, defects such as air inclusion, laminar flow, and flow lines are easily formed at the intersection of the molten metals. By increasing the cross-sectional area of the ingates at the corresponding locations, the filling flow and speed can be increased to balance the filling flow and speed of the rib, fastening, and frame cavities, thereby reducing the speed and temperature differences when the molten aluminum converge.

[0060] The defect prediction simulation in Figure 4(b) shows that liquid phase islands form thermal nodes at the four corners of the fastening part, and shrinkage defects will appear after solidification. The reason is that the wall thickness of the fastening part is relatively thick, which makes the wall thickness thicker at the four corners of the fastening part, resulting in heat not being easily dissipated, making this area the last part to solidify. In this case, the surrounding metal has solidified, forming a relatively closed space, making it impossible for this part of the molten metal to be effectively compensated for shrinkage, thus forming liquid phase islands. By adjusting the pouring speed and pressure, more uniform pouring can be achieved to reduce the generation of liquid phase islands. You can also add a ventilation system to reduce the generation of pores to avoid the formation of liquid phase islands.

[0061] Based on the simulation results and analysis above, the root cause of the aforementioned defects is the imbalance in the filling flow and speed of the rib, fastener, and frame cavities. The molten aluminum entering the cavity earlier differs from the temperature and speed of the molten aluminum entering later, which converges to form defects such as air inclusion, laminar flow, and flow lines. Therefore, the gating and overflow systems should be modified to balance the relationship between the local filling flow and pressure of the casting, ensuring a balanced filling speed for the rib, fastener, and frame, and synchronizing solidification and cooling times. Furthermore, an exhaust system can be added to reduce the formation of air holes and avoid the formation of hot spots at the corners of the fasteners.

[0062] Therefore, the present invention provides a die-casting mold for an aluminum alloy connecting bracket for new energy vehicles, including an upper mold 6, a lower mold 7, a pouring system 3 and an overflow system 4. The upper mold 6 can be engaged and separated relative to the lower mold 7. When the upper mold 6 and the lower mold 7 are engaged, the upper mold 6 and the lower mold 7 can form a casting cavity 2.

[0063] The casting cavity 2 includes a rib cavity 21 , a fastening cavity 22 and a frame cavity 23 .

[0064] The pouring system 3 includes a sprue 31, a runner 32, a branch runner 33, and an ingate 34. One end of the sprue 31 is connected to the main gate, and the other end is connected to a first runner 321 and a second runner 322. The first runner 321 and the second runner 322 are located on either side of the sprue 31. The first runner 321 is sequentially connected to a first branch runner 331, a second branch runner 332a, and a third branch runner 333. The second runner 322 is sequentially connected to a fourth branch runner 334, a fifth branch runner 335, and a sixth branch runner 336. The first branch runner 331, the third branch runner 333, the fourth branch runner 334, the fifth branch runner 335, and the sixth branch runner 336 intersect the first runner 321 and the second runner 322 perpendicularly, respectively. The second branch runner 332 intersects the first runner 321 at an angle of 110° to 165°. Furthermore, the cross-sectional areas of the first branch runner 331, the second branch runner 332, the third branch runner 333, the fourth branch runner 334, the fifth branch runner 335, and the sixth branch runner 336 are equal. The first branch runner 331 is connected to the rib portion cavity 21 through the first ingates 341, the second branch runner 332 and the third branch runner 333 are connected to the fastening portion cavity 22 through the second ingates 342 and the third ingates 343 respectively, the fourth branch runner 334, the fifth branch runner 335 and the sixth branch runner 336 are connected to the frame portion cavity 23 through the fourth ingates 344, the fifth ingates 345 and the sixth ingates 346 respectively, and the cross-sectional area of the second ingates 342, the third ingates 343, the fourth ingates 344 and the fifth ingates 345 is 3.35 cm 2 The cross-sectional area of the first gate 341 and the sixth gate 346 are both 2.25 cm 2 .

[0065] The overflow system includes multiple overflow grooves 4, which are respectively connected to the casting cavity 2. Among them, there is one overflow groove 4 connected to the rib cavity 21, which is arranged at the thin-wall position of the rib cavity 21. There are four overflow grooves 4 connected to the fastening cavity 22. An auxiliary overflow groove 5 is also arranged between the second inner gate 342 and the third inner gate 343. There are three overflow grooves 4 connected to the frame cavity 23.

[0066] As shown in the figure, the overflow trough 4 includes a connecting portion 41, a main portion 42 and an exhaust channel 43. The connecting portion 41 connects the main portion 42 with the casting cavity 2. One end of the exhaust channel 43 is connected to the main portion 43 and the other end leads to the outside of the mold.

[0067] During die casting, aluminum liquid is injected from the gate and enters the mold cavity through the sprue, runner, branch runner and inner gate in sequence. The condensed aluminum liquid that enters earlier and the gas and impurities in the mold cavity enter the main part through the connecting part of the overflow groove to stabilize the flow state of the aluminum liquid. The main part accommodates the condensed aluminum liquid and impurities, and the exhaust channel discharges the gas out of the mold.

[0068] MAGMASOFT software generates PQ based on the equipment and gate design plan 2 The relationship curve helps designers verify the ideal process area for the relationship between filling pressure and flow rate, thereby testing and judging the rationality of the design of the gate area. Enter different gate design related parameters in the software, and the software will automatically calculate the corresponding PQ 2 Relationship curve, check PQ 2 The process adaptation window is related to whether it is within the optimal process parameter combination range in the gray area.

[0069] like Figure 10 As shown, the cross-sectional area of the optimized second gate is input, and the PQ generated by the simulation is 2 The process curve is in the optimal region, which proves that the optimization scheme of changing the cross-sectional area of the second gate is feasible. 2 The relationship curve is shown in the figure. Parameters such as the maximum filling pressure, cavity filling time, and initial mold temperature of the initial process are also adjusted and optimized accordingly. The specific parameter improvements are shown in Table 2.

[0070] Table 2 Comparison of initial process and optimized solution parameters

[0071] Initial parameter name Numerical Optimization plan parameter name Numerical Initial mold temperature 180° Initial mold temperature 190° Cavity filling time 0.031s Cavity filling time 0.035s Ingate cross-sectional area <![CDATA[2.25cm 2 ]]> Ingate cross-sectional area <![CDATA[3.35cm 2 ]]> Maximum filling pressure 62.5Mpa Maximum filling pressure 64.6Mpa

[0072] To verify that each area of the casting achieves balanced filling pressure and flow, MAGMASOFT software was used again to simulate and verify the optimized solution. Simulation analysis of the filling process pressure and solidification temperature was also performed on the optimized solution, resulting in a comparative simulation curve of the pressure and temperature changes from the liquid phase to the solid phase during the die casting process of the optimized part.

[0073] like Figure 11(a) 、 11(b) As shown in the figure, from the comparison of the air pressure simulation at the intersection of the aluminum liquid filling ends before and after optimization, it can be seen that the initial design air pressure value is high, reaching 3567Mbar, while the air pressure value after optimization is reduced to 2302Mbar; this shows that the risk of gas inclusion tendency at this metal liquid intersection position is greatly reduced.

[0074] By selecting and placing simulation sensors at locations where shrinkage may occur during prediction, MAGMASOFT software can also generate heat exchange and temperature change curves between the molten metal and the mold at key locations to check whether the temperature curve during the solidification process is smooth. Figure 8 As shown in the figure, the heat conduction temperature curve between the local mold and the molten metal of the optimized casting shows a gentle decline, which proves that the casting has obtained a reasonable cooling and solidification rate in the process from liquid phase to solid phase; and avoids the shrinkage and other defects caused by excessive temperature gradient between the casting and the mold.

[0075] From the optimized simulation results, it can be seen that the optimized technical solution reduces the air pressure at the intersection of the aluminum liquid filling end, avoiding the excessive temperature gradient between the casting and the mold that causes defects such as shrinkage.

[0076] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A die-casting mold for an aluminum alloy connecting bracket for new energy vehicles, comprising an upper mold, a lower mold, a gating system, and an overflow drainage system. The upper mold can be separated and engaged with the lower mold, and when engaged, the upper and lower molds form a casting cavity. The casting cavity includes a rib cavity, a fastening cavity and a frame cavity, and the complexity is that the frame cavity is larger than the fastening cavity and larger than the rib cavity; The pouring system includes a sprue, a runner, a branch runner and an ingate; one end of the sprue is connected to the gate and the other end is connected to the runner. The runner is vertically connected to multiple branch runners, and each branch runner is connected to the casting cavity through a corresponding ingate; The number of branch runners connected to the frame cavity is greater than the number of branch runners connected to the fastening cavity, and the number of branch runners connected to the fastening cavity is greater than the number of branch runners connected to the rib cavity; The overflow system includes multiple overflow troughs, each connected to the casting cavity; wherein the number of overflow troughs connected to the fastening portion cavity is greater than the number of overflow troughs connected to the frame portion cavity, and the number of overflow troughs connected to the frame portion cavity is greater than the number of overflow troughs connected to the rib portion cavity; It is characterized by: The cross-sectional area of the ingate of the fastening portion cavity close to the rib portion cavity is larger than the cross-sectional area of the ingate of the rib portion cavity.

2. The die-casting mold of the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The gate is arranged in an oblique connection between the branch gate and the cross gate of the fastening part cavity close to the rib part cavity.

3. The die-casting mold of the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: An auxiliary overflow groove is provided at a middle position of the fastening portion cavity close to the inner gate.

4. The die-casting mold of the aluminum alloy connecting bracket for new energy vehicles according to claim 2, characterized in that: The inclination angle between the branch runner and the cross runner of the fastening part cavity close to the rib part cavity is 110° to 165°.

5. The die-casting mold of the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The inner gate is in a flat bell-mouth shape.

6. The die-casting mold for the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The number of branch runners connected to the rib cavity is 1 to 2, the number of branch runners connected to the fastening cavity is 2 to 4, and the number of branch runners connected to the frame cavity is 3 to 5.

7. The die-casting mold for the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The number of overflow grooves connected to the rib cavity is 1 to 2, the number of overflow grooves connected to the fastening cavity is 4 to 6, and the number of overflow grooves connected to the frame cavity is 3 to 5.

8. The die-casting mold for the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The rib portion cavity has a thin-walled portion, and the thin-walled portion is connected to an overflow groove.

9. The die-casting mold for the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The overflow trough comprises a main body, a connecting part and an exhaust channel. The connecting part connects the main body with the casting cavity. One end of the exhaust channel is connected to the main body, and the other end passes through the upper mold.

10. The die-casting mold of the aluminum alloy connecting bracket for new energy vehicles according to claim 1, characterized in that: The rib cavity is a thin-walled frame connecting rib, the fastening cavity has a thicker wall, the frame cavity has a relatively uniform wall thickness, and the thickness of the rib cavity and the fastening cavity is greater than the thickness of the frame cavity.

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