A method of forming a die cast

Abstract

The application relates to the technical field of die casting forming, in particular to a die casting forming method. The die casting forming method comprises the following steps: injecting metal liquid from a holding furnace into a compression chamber; making the temperature of the compression chamber be at a target temperature through at least a compression chamber heating device; pushing the metal liquid in the compression chamber into a cavity of a die casting mold through a die casting punch; making the temperature of the die casting mold be at the target temperature through at least a mold heating device; and obtaining a die casting after the metal liquid is cooled and formed in the cavity. The independent compression chamber heating device is arranged in the compression chamber, the compression chamber is actively heated after the metal liquid is injected into the compression chamber and during the pushing process, the metal liquid is kept in a suitable flowing temperature interval, the viscosity and the surface tension of the metal liquid are effectively reduced, the metal liquid is prevented from forming a solidification layer in the compression chamber too early, and forming defects such as cold shut, underfill and flow mark are obviously reduced.

Description

Technical Field

[0001] This invention relates to the field of die casting technology, specifically to a method for forming die castings. Background Technology

[0002] In existing die casting technology, heating devices are typically only installed at the die casting mold to regulate the temperature of the mold cavity surface, ensuring that the molten metal cools and solidifies according to a predetermined solidification sequence after filling. However, for the pressure chamber stage before the molten metal enters the mold cavity, existing technologies generally do not include heating devices, relying solely on the temperature of the molten metal itself to maintain its fluidity.

[0003] Due to the lack of active heating methods for the pressure chamber, the following problems arise in actual production: First, after the molten metal is injected into the pressure chamber from the holding furnace, heat is rapidly dissipated during contact with the inner wall of the pressure chamber, resulting in a drop in the temperature of the molten metal, an increase in viscosity, an increase in surface tension, and a significant decrease in fluidity, making it difficult to smoothly fill the mold cavity during subsequent injection. Second, the molten metal forms a solidified layer (cold material) too early in the pressure chamber. After this cold material is pushed into the cavity by the punch, it will not blend well with the subsequent hot molten metal, resulting in forming defects such as cold shuts, undercasting, and flow marks in the casting. Third, in order to ensure that the molten metal does not solidify too early in the pressure chamber, it is necessary to increase the furnace outlet temperature or speed up the production cycle, but this brings new problems such as increased energy consumption, aggravated oxidation and gas absorption of the molten metal, and a shortened thermal fatigue life of the pressure chamber.

[0004] Furthermore, due to the lack of heating means in the pressure chamber in the existing technology, the temperature difference gradient between the pressure chamber and the mold is unreasonable. The temperature state of the molten metal in the pressure chamber and the temperature state after entering the mold cavity are not effectively connected, which causes a break in the temperature management of the entire die casting process and makes it difficult to achieve coordinated temperature control of the entire process from molten metal injection into the pressure chamber to filling the mold cavity. Summary of the Invention

[0005] The purpose of this invention is to propose a forming method for die casting parts, which aims to solve the technical problems of poor fluidity of molten metal and easy occurrence of cold shuts and undercasting due to the lack of active heating means in existing pressure chambers.

[0006] To achieve the above objectives, the present invention proposes a method for forming die-cast parts, providing a pressure chamber and a die-casting mold, wherein the pressure chamber is equipped with a pressure chamber heating device and the die-casting mold is equipped with a mold heating device; The method for forming the die-casting part includes the following steps: injecting molten metal from a holding furnace into the pressure chamber; bringing the temperature of the pressure chamber to a target temperature using at least the pressure chamber heating device; filling the cavity of the die-casting mold with molten metal from the pressure chamber by being pushed by a die-casting punch; bringing the temperature of the die-casting mold to a target temperature using at least the mold heating device; and obtaining the die-casting part after the molten metal cools and solidifies in the cavity.

[0007] Preferably, the pressure chamber heating device includes an electromagnetic induction coil wound around the outer perimeter of the pressure chamber, the electromagnetic induction coil generating induced eddy currents to heat the pressure chamber.

[0008] Preferably, a first temperature sensor is installed at a plurality of preset positions within the die-casting mold, and a second temperature sensor is installed at a plurality of preset positions within the pressure chamber; the first temperature sensor detects the temperature information of each preset position of the die-casting mold at a preset time point, and the second temperature sensor detects the temperature information of each preset position of the pressure chamber at the preset time point; The data processing module receives temperature information detected by the first temperature sensor and the second temperature sensor respectively, compares the temperature information detected at each preset location at the preset time point with the target temperature at the corresponding preset location at the preset time point, generates temperature control information based on the comparison result, and then sends the temperature control information to the control system. The control system adjusts the heating temperature of the pressure chamber heating device and the heating temperature of the mold heating device according to the temperature control information, so that each preset position reaches the corresponding target temperature at a preset time point.

[0009] Preferably, the multiple preset positions within the die-casting mold each have their own independent first target temperature, and the first target temperatures of at least two of the preset positions are different from each other; The multiple preset positions within the pressure chamber each have their own independent second target temperature, and the second target temperatures of at least two of the preset positions are different from each other.

[0010] Preferably, the pressure chamber is provided with cooling water holes in its wall, the cooling water holes are connected to a cooling system, and the cooling system introduces a cooling medium into the cooling water holes to cool the pressure chamber; the cooling system is signal-connected to the control system to adjust the temperature of the cooling medium so that each preset position of the pressure chamber reaches the target temperature at the corresponding preset time point; The cooling system also includes a control valve. The control system adjusts the cooling start time and cooling duration of the pressure chamber at a preset time point by controlling the opening and closing time and the opening duration of the control valve of the cooling system.

[0011] Preferably, the die-casting mold is equipped with multiple mold heating devices, each mold heating device corresponding to a different preset position of the die-casting mold, so as to independently heat different areas of the die-casting mold; The mold heating device is connected to the control system via a signal. The control system adjusts the heating temperature and heating duration of each mold heating device according to the temperature control information, so that each preset position of the die casting mold reaches the target temperature at the corresponding preset time point. The die-casting mold is equipped with multiple cooling devices, each of which corresponds to a different preset position of the die-casting mold, so as to independently cool different areas of the die-casting mold; The cooling device is connected to the control system via a signal. The control system adjusts the temperature of the cooling medium and / or the duration of the cooling medium flow in each cooling device according to the temperature control information, so that each preset position of the die-casting mold reaches the target temperature at the corresponding preset time point.

[0012] Preferably, during the process of filling the molten metal in the pressure chamber into the cavity of the die-casting mold, the cavity is evacuated so that the pressure inside the cavity during die casting is controlled at 40~90 MPa.

[0013] Preferably, the die-casting mold has a gate, through which molten metal enters the cavity from the pressure chamber; the cross-sectional thickness of the gate is 2-6 mm. The gating ports are multiple gating ports spaced apart along the entrance direction of the cavity to achieve segmented gating.

[0014] Preferably, during die casting, the volume of molten metal in the pressure chamber accounts for 20-60% of the chamber's volume.

[0015] Preferably, the injection speed of the die-casting punch is 4~6m / s; the ratio of the cross-sectional area of ​​the gate to the cross-sectional area of ​​the die-casting punch is 1:5~30.

[0016] Preferably, the molten metal is molten aluminum; the temperature of the molten aluminum in the holding furnace is 640~730℃.

[0017] The die-casting method disclosed in this invention has the following beneficial effects: By setting an independent pressure chamber heating device, the pressure chamber is actively heated after the molten metal is injected into the pressure chamber and during the injection process, keeping the molten metal within a suitable flow temperature range. This effectively reduces its viscosity and surface tension, preventing the molten metal from forming a solidified layer (cold material) prematurely in the pressure chamber, thereby significantly reducing forming defects such as cold shuts, undercasting, and flow marks. Simultaneously, it reduces the thermal shock to the pressure chamber wall during molten metal injection, extending the service life of the pressure chamber. Furthermore, the heating effect of the pressure chamber heating device works synergistically with that of the mold heating device, creating a reasonable temperature gradient transition between the temperature maintenance of the molten metal in the pressure chamber and its cooling and forming after entering the mold cavity. This avoids temperature breakpoint problems caused by excessive temperature difference between the pressure chamber and the mold. At the same time, by heating the pressure chamber with the pressure chamber heating device, there is no need to excessively increase the furnace exit temperature to raise the temperature of the molten metal entering the mold cavity, thereby reducing energy consumption and the tendency of the molten metal to oxidize and absorb gas at high temperatures, which is beneficial for obtaining high-quality, airtight die-cast parts. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic cross-sectional view of the pressure chamber of the present invention; Figure 2 This is a schematic diagram of the die-casting mold of the present invention.

[0020] In the attached diagram: 1-Pressure chamber, 11-Electromagnetic induction coil, 2-Die casting mold.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] A method for forming a die-casting part, comprising a pressure chamber 1 and a die-casting mold 2, wherein the pressure chamber 1 is provided with a pressure chamber heating device and the die-casting mold 2 is provided with a mold heating device; The die-casting method includes the following steps: injecting molten metal from a holding furnace into the pressure chamber 1; bringing the temperature of the pressure chamber 1 to a target temperature using at least the pressure chamber heating device (e.g., heating the pressure chamber 1 using the pressure chamber heating device or using the cooling device described below); filling the cavity of the die-casting mold 2 with molten metal from the pressure chamber 1 by pushing it with a die-casting punch; bringing the temperature of the die-casting mold 2 to a target temperature using at least the mold heating device (e.g., heating the pressure chamber 1 using the die-casting mold heating device or using the cooling system described below); stopping heating after reaching the target temperature; and obtaining the die-casting part after the molten metal cools and solidifies in the cavity.

[0026] In this scheme, by setting an independent heating device in the pressure chamber 1, the pressure chamber 1 is continuously heated after the molten metal is injected into the pressure chamber 1 and during the injection process, so that the molten metal is kept in a suitable flow temperature range, significantly reducing its viscosity and surface tension, ensuring that the molten metal has a good flow state in the pressure chamber 1, and providing a prerequisite for smooth filling of the mold cavity in the future; and the heating effect of the pressure chamber heating device can maintain a suitable temperature on the inner wall of the pressure chamber 1, preventing the molten metal from forming a solidified layer too early in the pressure chamber 1, thereby significantly reducing the possibility of cold material entering the cavity, and effectively improving the internal density and appearance quality of the die casting.

[0027] Furthermore, by adding a heating device to pressure chamber 1, the heating of pressure chamber 1 by the pressure chamber heating device can be coordinated with the heating of the mold by the mold heating device to form a temperature gradient transition of the molten metal from pressure chamber 1 to the cavity. The pressure chamber heating device / cooling structure can maintain a suitable temperature state for the molten metal before entering the cavity, while the mold heating device / cooling device can cool and form the molten metal according to the preset solidification conditions after entering the cavity. Together, they construct a temperature management system for the entire process of the molten metal from pressure chamber 1 to the cavity, avoiding the temperature breakpoint problem caused by excessive temperature difference between pressure chamber 1 and the mold, ensuring a smooth temperature transition of the molten metal throughout the process, and thus improving the forming quality of the die-cast parts. The actual operation process of temperature control depends on the product structure. Some parts of the product have a long heating time, while others have a short heating time. Therefore, while some parts of the same mold are being heated, another part may be cooling.

[0028] Furthermore, the pressure chamber heating device includes an electromagnetic induction coil 11 wound around the periphery of the pressure chamber 1, the electromagnetic induction coil 11 generating induced eddy currents to heat the pressure chamber 1.

[0029] In this embodiment, as Figure 1 As shown, by using an electromagnetic induction coil 11 wound around the periphery of the pressure chamber 1 as the pressure chamber heating device, induced eddy currents are directly generated on the wall of the pressure chamber 1 using the principle of electromagnetic induction to heat the pressure chamber 1 itself, achieving non-contact heating and avoiding the heat transfer loss and easy damage of heating elements that exist in traditional contact heating methods. At the same time, the electromagnetic induction coil 11 is connected to the control system described below, which can adjust the heating time and heating temperature of the electromagnetic induction coil 11 in real time according to the actual needs of the die casting process, achieving precise control of the wall temperature of the pressure chamber 1. This ensures that the molten metal maintains a suitable flow temperature in the pressure chamber 1, and avoids the pressure chamber 1 wall from overheating and accelerating thermal fatigue failure. Thus, while improving the forming quality of the die casting, it also extends the service life of the pressure chamber 1 and reduces unnecessary energy consumption.

[0030] Of course, in other embodiments, the pressure chamber heating device may also use heating elements such as resistance wires, and adjustments can be made according to different needs.

[0031] Furthermore, a first temperature sensor is installed at a plurality of preset positions within the die-casting mold 2, and a second temperature sensor is installed at a plurality of preset positions within the pressure chamber 1; the first temperature sensor detects the temperature information of each preset position of the die-casting mold 2 at a preset time point, and the second temperature sensor detects the temperature information of each preset position of the pressure chamber 1 at the preset time point; The data processing module receives temperature information detected by the first temperature sensor and the second temperature sensor respectively, compares the temperature information detected at each preset location at the preset time point with the target temperature at the corresponding preset location at the preset time point, generates temperature control information based on the comparison result, and then sends the temperature control information to the control system. The control system adjusts the heating temperature of the pressure chamber heating device and the heating temperature of the mold heating device according to the temperature control information, so that each preset position reaches the corresponding target temperature at a preset time point.

[0032] A temperature control system for pressure chamber 1 is generated by installing second temperature sensors at multiple preset locations within pressure chamber 1, such as... Figure 2 As shown, each preset position is arranged differently according to the structural characteristics of the casting (including at least one of the following: casting wall thickness position, thin wall position, deep cavity position, gating position, and historical defect position at positions abcd). The temperature information of each preset position in the pressure chamber 1 is collected in real time by the second temperature sensor. The data processing module compares the detected temperature of each preset position at the preset time point with the corresponding target temperature and generates temperature control information. According to the control information, the control system commands the electromagnetic induction coil 11 of the pressure chamber 1 to apply an electromagnetic field around the barrel of the die casting machine. This causes the originally viscous and poorly fluid "yogurt-like" molten metal (aluminum liquid) to break down its surface tension under the action of electromagnetic force and transform into a highly fluid "water-like" or "milk-like" fluid. Each preset position in the pressure chamber 1 reaches the target temperature at the corresponding preset time point, which effectively ensures the fluidity of the aluminum liquid in the pressure chamber 1 and solves the problem of incomplete filling caused by insufficient fluidity of the aluminum liquid.

[0033] Meanwhile, this application generates a mold temperature control system by installing first temperature sensors at multiple preset positions within the die-casting mold 2. The first temperature sensors collect temperature information at each preset position of the mold in real time. The data processing module integrates the temperature data of the pressure chamber 1 and both sides of the mold to generate unified temperature control information. The control system commands the heating valves corresponding to the mold heating device (and the cooling valves corresponding to the mold cooling device described below) to adjust according to the control information, so that each preset position of the mold reaches its target temperature at the corresponding preset time point, thereby achieving precise control of the local temperature of the mold.

[0034] Therefore, the first and second temperature sensors independently collect temperature data from the mold side and the pressure chamber 1 side, respectively. The data processing module integrates and analyzes the temperature information from both sides, and the control system outputs differentiated control commands to the pressure chamber heating device and the mold heating device, forming a closed-loop temperature control system of independent acquisition, unified integration, and linkage control on both sides of "pressure chamber 1 - die casting mold 2". This avoids the defects of independent temperature control of pressure chamber 1 and mold temperature control and lack of linkage, and realizes the temperature collaborative management of the entire process of molten metal from pressure chamber 1 to the cavity. After maintaining a high fluidity state in pressure chamber 1, the molten metal enters the cavity and solidifies in an orderly manner under the precise temperature field conditions of each preset position of the mold. This effectively avoids die casting defects such as shrinkage cavities, porosity, cold shuts, flow marks, scratches, and cracks caused by temperature runaway, and significantly improves the forming quality and internal density of die castings.

[0035] Furthermore, multiple preset positions within the die-casting mold 2 each have their own independent first target temperature, and at least two of the preset positions have different first target temperatures; multiple preset positions within the pressure chamber 1 each have their own independent second target temperature, and at least two of the preset positions have different second target temperatures. The data processing module compares the temperature information detected at each preset position with its corresponding target temperature to generate temperature control information for each preset position.

[0036] By independently setting target temperatures at multiple preset locations within the die-casting mold 2 and pressure chamber 1, and ensuring that the target temperatures at different locations are distinct, precise temperature control can be achieved for each zone based on the actual heat load and structural differences of each part. This effectively avoids localized overheating or overcooling caused by overall heating or cooling. Combined with feedback control from the real-time temperature detection and data processing module, the heating power of each area can be dynamically adjusted, resulting in a more uniform and stable temperature field distribution in pressure chamber 1 and die-casting mold 2. This significantly reduces internal thermal stress in the die-casting parts, minimizes defects such as shrinkage cavities, thermal cracks, and dimensional deformation, and ultimately improves the density of the die-casting parts and the dimensional accuracy of the finished product.

[0037] Furthermore, the pressure chamber 1 is provided with cooling water holes in its wall. The cooling water holes are connected to a cooling system. The cooling system introduces a cooling medium into the cooling water holes to cool the pressure chamber 1. The cooling system is signal-connected to the control system to adjust the temperature of the cooling medium so that each preset position of the pressure chamber 1 reaches the target temperature at the corresponding preset time point. The cooling system also includes a control valve. The control system adjusts the cooling start time and cooling duration of the pressure chamber 1 at a preset time point by controlling the opening and closing time and the opening duration of the control valve of the cooling system.

[0038] In this embodiment, by setting cooling water holes in the wall of the pressure chamber 1, and connecting the cooling water holes to the cooling system, the cooling system introduces cooling medium into the cooling water holes under the signal control of the control system to actively cool the pressure chamber 1. At the same time, the control system precisely adjusts the cooling start time and cooling duration of the pressure chamber 1 at a preset time point by controlling the opening and closing time and opening duration of the cooling system control valve, thereby achieving precise time dimension control of the cooling process of the pressure chamber 1. The cooling system works in conjunction with the aforementioned electromagnetic induction heating device—the electromagnetic induction coil 11 actively heats the pressure chamber 1 to break down the surface tension of the molten aluminum and improve its fluidity. The cooling system, on the other hand, moderately cools the pressure chamber 1 by adjusting the temperature of the cooling medium and controlling the opening and closing of the valve to prevent the walls of the pressure chamber 1 from overheating. Under the unified control of the control system, the two form a two-way dynamic adjustment mechanism of "heating-cooling", which ensures that each preset position of the pressure chamber 1 reaches the target temperature precisely at the corresponding preset time point. This ensures that the molten aluminum maintains a highly fluid "watery" or "milky" state in the pressure chamber 1, while also preventing thermal fatigue cracking of the walls of the pressure chamber 1 due to continuous high temperature. At the same time, it prevents the molten aluminum from solidifying prematurely in the pressure chamber 1 due to excessive cooling, thus ensuring the stability of the die casting quality.

[0039] Furthermore, the die-casting mold 2 is equipped with multiple mold heating devices, each of which corresponds to a different preset position of the die-casting mold 2, so as to independently heat different areas of the die-casting mold 2; The mold heating device is connected to the control system by signal. The control system adjusts the heating temperature and heating duration of each mold heating device according to the temperature control information, so that each preset position of the die casting mold 2 reaches the target temperature at the corresponding preset time point. The die-casting mold 2 is equipped with multiple cooling devices, each of which corresponds to a different preset position of the die-casting mold 2, so as to independently cool different areas of the die-casting mold 2. The cooling device is connected to the control system via a signal. The control system adjusts the temperature of the cooling medium and / or the duration of the cooling medium flow in each of the cooling devices according to the temperature control information, so that each preset position of the die-casting mold 2 reaches the target temperature at the corresponding preset time point.

[0040] In this embodiment, by installing multiple mold heating devices within the die-casting mold 2, each corresponding to a different preset position within the mold 2, independent heating of different areas of the mold 2 is achieved. This enables precise point-to-point control of the mold's local temperature (both point-like and line-like areas can be heated). Simultaneously, each mold heating device is connected to the control system. Based on temperature control information generated by the data processing module, the control system adjusts the heating temperature and duration of each heating device, ensuring that each preset position of the mold independently reaches its target temperature at its corresponding preset time point. Therefore, the mold heating devices can output differentiated heating power and duration for different areas of the mold (such as areas with thick or thin casting walls, deep cavities, and gate locations). This allows for targeted heating of areas with insufficient local temperature to prevent premature solidification of the molten metal and cold shuts, while also enabling linear tracking heating of deep cavities or complex structural areas to ensure smooth molten metal filling, effectively improving the uniformity and adjustability of the mold's thermal field.

[0041] Meanwhile, this application also installs multiple cooling devices within the die-casting mold 2. Each cooling device corresponds to a different preset position on the mold, enabling independent cooling of different areas of the mold. The cooling devices are connected to the control system, which adjusts the cooling medium temperature and / or cooling medium flow duration of each device based on temperature control information, ensuring that each preset position on the mold reaches the target temperature at the corresponding preset time point. Through the coordinated operation of multiple mold heating devices and multiple cooling devices at each preset position on the mold, a two-way independent adjustment mechanism of "local heating-local cooling" is formed for the same or different areas of the mold under the unified control of the control system. This mechanism can preheat the mold before the molten metal is filled to reduce filling resistance, and apply differentiated cooling intensities to different areas of the cavity after the molten metal is filled to control the solidification sequence. This avoids molding defects such as shrinkage cavities, porosity, sticking, and hot cracks caused by local overheating, as well as cold shuts, flow marks, and undercasting caused by local overcooling. It significantly improves the dimensional accuracy, internal density, and surface quality of the die-cast parts, and effectively reduces mold cracking failure caused by local thermal stress concentration, thus extending the service life of the mold.

[0042] Furthermore, during the process of filling the molten metal in the pressure chamber 1 into the cavity of the die-casting mold 2, the cavity is evacuated to control the pressure inside the cavity at 40~90 MPa during die casting.

[0043] During die casting, a vacuum is drawn into the mold cavity as the molten metal fills the cavity. This, combined with the synergistic effect of high-pressure die casting (casting pressure 40~90MPa), reduces residual gas in the cavity to avoid air entrapment. At the same time, the high pressure forces the molten metal to fill every tiny part of the cavity and continuously feeds the material during solidification. This significantly reduces porosity and shrinkage defects inside the casting, improves the density and mechanical properties of the die casting, and is especially suitable for automotive structural parts with high airtightness requirements.

[0044] Furthermore, the die-casting mold 2 has a gate, through which molten metal enters the cavity from the pressure chamber 1; the cross-sectional thickness of the gate is 2~6mm; the gate consists of multiple gates spaced apart along the entrance direction of the cavity to achieve segmented casting.

[0045] By limiting the thickness of the gate section of the die-casting mold 2 to 2~6mm, the molten metal can obtain sufficient filling speed when flowing through the gate, ensuring that the molten metal can quickly and smoothly fill all parts of the cavity, while avoiding incomplete filling due to insufficient flow rate caused by an excessively thick gate or excessive flow rate causing the mold to be washed away due to an excessively thin gate.

[0046] By setting multiple gates spaced apart along the cavity entrance direction to achieve segmented pouring, molten metal can enter the cavity simultaneously from multiple positions, effectively shortening the filling path of the molten metal. This avoids the problems of excessively long molten metal flow and insufficient filling at the far end caused by a single gate. At the same time, the segmented pouring method with multiple gates can also balance the filling speed and pressure distribution in different areas of the cavity, reduce air entrapment and turbulence in the molten metal during the filling process, significantly reduce forming defects such as cold shuts, flow marks, and undercasting caused by unreasonable filling paths, and further improve the internal quality and appearance of die castings.

[0047] Furthermore, during die casting, the volume of molten metal in chamber 1 accounts for 20% to 60% of the total volume of chamber 1. By controlling the percentage of molten metal in chamber 1 to its total volume within this range, two issues are avoided: firstly, excessive air content in chamber 1 due to low fill percentage (below 20%) leads to gas entrainment during injection, causing internal defects such as porosity and shrinkage; secondly, excessive residence time of molten metal in chamber 1 results in excessive heat loss and decreased fluidity. On the other hand, excessive fill percentage (above 60%) leads to insufficient space in the upper part of chamber 1, causing severe pressure fluctuations during injection, poor molten metal filling stability, and excessive thermal and mechanical loads on the walls of chamber 1. By controlling the fill percentage within a reasonable range and coordinating it with the active heating effect of the chamber heating device, the molten metal maintains a suitable flow state and stable pressure transmission conditions within chamber 1, thereby improving the process stability of the die casting process and the internal quality of the casting.

[0048] Furthermore, the injection speed of the die-casting punch is 4~6m / s; the ratio of the cross-sectional area of ​​the gate to the cross-sectional area of ​​the die-casting punch is 1:5~30.

[0049] Specifically, by controlling the injection speed of the die-casting punch at 4~6m / s and setting the ratio of the cross-sectional area of ​​the gate to the cross-sectional area of ​​the die-casting punch to 1:5~30, the molten metal receives a suitable velocity amplification effect when flowing through the gate. This ensures that the molten metal fills the cavity quickly with sufficient kinetic energy, avoiding defects such as flow marks and cold shuts caused by excessively low filling speeds leading to rapid temperature drops during filling. It also avoids damage such as thermal fatigue cracking, sticking, and chipping caused by excessively high molten metal velocity at the gate, which can result in severe turbulence and impacts on the mold cavity surface due to continuous scouring by high-temperature molten metal. This effectively protects the surface quality of the mold cavity, extends the service life of the mold, and the stable filling speed helps reduce air entrapment in the molten metal, improving the density of the internal structure of the die-casting parts.

[0050] Furthermore, the molten metal is molten aluminum; the temperature of the molten aluminum in the holding furnace is 640~730℃.

[0051] The above-described forming method is particularly suitable for the preparation of aluminum alloy die castings (and can also be applied to die castings of other metals such as zinc, magnesium, and copper alloys). Specifically, the molten metal used in the preparation is aluminum. The temperature of the molten aluminum in the holding furnace is controlled at 640~730℃, ensuring that the molten aluminum is within a suitable flow temperature range before being injected into pressure chamber 1. This guarantees sufficient fluidity for subsequent injection filling while avoiding excessively high temperatures (above 730℃) that could lead to severe oxidation and gas absorption in the molten aluminum, increase the risk of porosity defects in the casting, and accelerate thermal fatigue damage to pressure chamber 1 and the mold.

[0052] In actual production, die casting is carried out according to the following process: a pressure chamber 1 and a die casting mold 2 are provided. The pressure chamber 1 is equipped with a pressure chamber heating device (such as an electromagnetic induction coil 11), and the die casting mold 2 is equipped with a mold heating device. The die casting mold 2 is fixed on the moving and fixed templates of the die casting machine, and the mold is preheated to 120~220℃ by the mold heating device. A layer of release agent is evenly sprayed on the inner surface of the mold cavity. Molten aluminum at a temperature of 640~730℃ in the holding furnace is injected into the pressure chamber 1, and the pressure chamber 1 is heated by the pressure chamber heating device. The molten aluminum in the pressure chamber 1 is filled into the cavity of the die casting mold 2 by the injection punch at an injection speed of 4~6m / s. The casting pressure of the system is controlled at 40~90MPa during die casting. During the filling process, the die casting mold 2 is heated by the mold heating device to maintain the target temperature at each preset position of the mold. After the molten aluminum cools and solidifies in the cavity, the mold is opened and the die casting is taken out.

[0053] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for forming a die-cast part, characterized in that, A pressure chamber (1) and a die-casting mold (2) are provided. The pressure chamber (1) is equipped with a pressure chamber heating device, and the die-casting mold (2) is equipped with a mold heating device. The forming method of the die casting includes the following steps: injecting molten metal from a heat-preserving furnace into the pressure chamber (1); bringing the temperature of the pressure chamber (1) to a target temperature at least through the pressure chamber heating device; filling the cavity of the die casting mold (2) with molten metal from the pressure chamber (1) by pushing with a die casting punch; bringing the temperature of the die casting mold (2) to a target temperature at least through the mold heating device; and obtaining the die casting after the molten metal cools and solidifies in the cavity.

2. The method for forming a die-cast part according to claim 1, characterized in that, First temperature sensors are installed at multiple preset positions in the die-casting mold (2), and second temperature sensors are installed at multiple preset positions in the pressure chamber (1). The first temperature sensors detect the temperature information of each preset position in the die-casting mold (2) at a preset time point, and the second temperature sensors detect the temperature information of each preset position in the pressure chamber (1) at the preset time point. The data processing module receives temperature information detected by the first temperature sensor and the second temperature sensor respectively, compares the temperature information detected at each preset location at the preset time point with the target temperature at the corresponding preset location at the preset time point, generates temperature control information based on the comparison result, and then sends the temperature control information to the control system. The control system adjusts the heating temperature of the pressure chamber heating device and the heating temperature of the mold heating device according to the temperature control information, so that each preset position reaches the corresponding target temperature at a preset time point.

3. The method for forming a die-cast part according to claim 2, characterized in that, The multiple preset positions within the die-casting mold (2) each have their own independent first target temperature, and the first target temperatures of at least two of the preset positions are different from each other; The multiple preset positions in the pressure chamber (1) each have their own independent second target temperature, and the second target temperatures of at least two of the preset positions are different from each other.

4. The method for forming a die-cast part according to claim 3, characterized in that, The pressure chamber (1) is provided with cooling water holes in its wall. The cooling water holes are connected to a cooling system. The cooling system introduces a cooling medium into the cooling water holes to cool the pressure chamber (1). The cooling system is connected to the control system to adjust the temperature of the cooling medium so that each preset position of the pressure chamber (1) reaches the target temperature at the corresponding preset time point. The cooling system also includes a control valve. The control system adjusts the cooling start time and cooling duration of the pressure chamber (1) at the preset time point by controlling the opening and closing time and the opening duration of the control valve of the cooling system.

5. The method for forming a die-cast part according to claim 3, characterized in that, The die-casting mold (2) is equipped with a plurality of mold heating devices, each mold heating device corresponding to a different preset position of the die-casting mold (2) to independently heat different areas of the die-casting mold (2); The mold heating device is connected to the control system. The control system adjusts the heating temperature and heating duration of each mold heating device according to the temperature control information, so that each preset position of the die casting mold (2) reaches the target temperature at the corresponding preset time point. The die-casting mold (2) is equipped with multiple cooling devices, each of which corresponds to a different preset position of the die-casting mold (2) to independently cool different areas of the die-casting mold (2); The cooling device is connected to the control system by signal. The control system adjusts the temperature of the cooling medium and / or the duration of the cooling medium flow of each cooling device according to the temperature control information, so that each preset position of the die-casting mold (2) reaches the target temperature at the corresponding preset time point.

6. The method for forming a die-cast part according to claim 1, characterized in that, During the process of filling the molten metal in the pressure chamber (1) into the cavity of the die-casting mold (2), the cavity is evacuated so that the pressure in the cavity during die casting is controlled at 40~90Mpa.

7. The method for forming a die-cast part according to claim 1, characterized in that, The die-casting mold (2) has a gate, through which molten metal enters the cavity from the pressure chamber (1); the cross-sectional thickness of the gate is 2~6mm. The gating ports are multiple gating ports spaced apart along the entrance direction of the cavity to achieve segmented gating.

8. The method for forming a die-cast part according to claim 1, characterized in that, During die casting, the volume of molten metal in the pressure chamber (1) accounts for 20-60% of the total volume of the pressure chamber (1).

9. The method for forming a die-cast part according to claim 7, characterized in that, The injection speed of the die-casting punch is 4~6m / s; the ratio of the cross-sectional area of ​​the gate to the cross-sectional area of ​​the die-casting punch is 1:5~30.

10. The method for forming a die-cast part according to claim 1, characterized in that, The molten metal is molten aluminum; the temperature of the molten aluminum in the holding furnace is 640~730℃.

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