Alloy high pressure casting mold, high pressure casting device and casting method

Abstract

A high-pressure casting device and alloy high-pressure casting mold thereof, the mold comprising: a sprue, a cross runner, an ingate, a slag bag, and a centralized exhaust port, the sprue and the cross runner connected vertically to each other are arranged at the center of the casting, the cross runner is connected to the ingate with decreasing cross-sectional area, the slag bag is arranged at the filling end of the casting or the intersection of aluminum liquid, and exhaust channels are connected at the end of each slag bag, and the exhaust channels are connected in parallel and connected in series to the centralized exhaust port at the intersection. A casting method is also provided accordingly, including: when the alloy melt is added into the pressure chamber through the quantitative furnace, the punch fills the melt into the sprue, and in the process, the pressure chamber and the cavity are vacuumed, and then the punch further fills the melt into the U-shaped cross runner and gradually fills it, and the filling speed is accelerated before the melt approaches the ingate position of the casting, and at the same time, the vacuum valve is triggered to close at this position, and then the punch continues to push the melt into the cavity through the ingate until the filling is completed, thereby ensuring the product quality.

Description

Technical Field

[0001] The invention relates to the field of alloy high pressure casting, and in particular to an alloy high pressure casting mold, a device and a casting method, in particular to a casting device and a process method for super large aluminum alloy die castings for vehicle bodies. Background Art

[0002] With the development of heat-treatment-free alloys and the launch of super-large die-casting machines, the technical and cost advantages brought by super-large die-casting parts at the body level are increasingly accepted by OEMs. Molds are essential process equipment for modern industries, especially in the automotive, radio, aviation, instrumentation, and daily necessities industries. The development of super-large molds and the design concept of the pouring system are still in the exploratory stage. The design of the mold pouring scheme generally needs to consider the alloy characteristics, product service requirements, product structure, product porosity requirements, product mechanical performance requirements, and also the reliability and cost competitiveness of the mold in production. The overall mold structure design still has strong technical barriers.

[0003] For the production of large-scale die-casting machines, due to the physical properties of alloys that do not require heat treatment, such as poor fluidity, easy sticking to the mold, and a close correlation between mechanical properties and microstructure, the product and mold structure design is more challenging than the traditional high-pressure mold design. It is necessary to take into account the mold temperature field design, flow filling distance, casting process and vacuum process requirements.

[0004] At present, the single-sided fan-shaped casting scheme used in similar large-scale die-castings in the industry often has problems such as too long aluminum liquid flow distance and severe heat loss, which leads to a significant decline in the mechanical properties and filling integrity at the end of the casting, and the casting scrap rate is over 20%, which significantly increases the production cost.

[0005] Therefore, the casting process design proposed in the present invention helps to reduce the production cost of such products, increase the application scope of integrated die-casting structural parts and form cost advantages. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to propose a pouring and exhaust structure that is particularly suitable for large die-casting molds, which can effectively solve the problems of poor end filling and unqualified mechanical properties of large die-casting structural parts, and further reduce the stress deformation of the casting after cooling and mold opening.

[0007] According to one aspect of the present invention, there is provided an alloy high-pressure casting mold, comprising: a straight runner, a cross runner, an ingate, a slag bag, and a centralized exhaust port provided with a vacuum valve, wherein the cross runner and the straight runner arranged at the center of the casting are connected perpendicularly to each other, the cross runner is connected to the ingate in a manner of decreasing cross-sectional area toward the ingate, the slag bag is arranged at the filling end of the casting or the intersection of the alloy melt, an exhaust channel is connected to the end of each slag bag, and the exhaust channels are connected in parallel and connected in series to the centralized exhaust port at the intersection.

[0008] Preferably, it can be arranged as follows: the thickness of the inner gate is 3.0 to 4.5 mm, and constitutes a continuous inner gate structure; the cross runner is a U-shaped structure; the area of ​​the inner gate connected to the casting covers more than 3 / 4 of the side wall of the casting window; the cross runner forms a cross-sectional area convergence structure in a conical manner.

[0009] Preferably, the effective exhaust area of ​​the centralized exhaust port is 25% to 35% of the inner gate area.

[0010] According to another aspect of the present invention, there is provided a high-pressure casting device, which is provided with a quantitative furnace, a punch, a vacuum machine provided with a vacuum valve, a control unit and any of the above-mentioned alloy high-pressure casting molds, wherein the cross-sectional area of ​​the punch is 1 / 15 to 1 / 9 of the cross-sectional area of ​​the inner gate.

[0011] According to another aspect of the present invention, there is provided a method for casting an alloy casting, which is characterized in that it is used for casting the above-mentioned high-pressure casting device, and comprises the following steps: after the molten alloy is added into the pressure chamber through the quantitative furnace, the punch fills the molten alloy into the straight runner, during which the pressure chamber and the cavity are evacuated, and then the punch further fills the molten alloy into the U-shaped cross runner and gradually fills the runner, and the filling speed is accelerated before the molten alloy approaches the position of the inner gate of the casting, and at the same time, the vacuum valve is triggered to close at this position, and then the punch continues to push the molten alloy into the cavity through the inner gate until the filling is completed.

[0012] Preferably, the control unit is used to control the exhaust process of the vacuum valve in such a way that the vacuum degree of the cavity during the filling process meets ≤80mbar; and / or, in the stage of accelerating the filling speed, the gate speed is 45-70m / s, and the filling time is less than 100ms.

[0013] Preferably, the above casting method is used for casting an aluminum alloy car body; and / or the ratio of the cross-sectional area of ​​the sprue to the material cake at the center of the casting is 1 / 10 to 1 / 6.

[0014] As mentioned above, the present invention proposes a U-shaped fully enclosed runner structure for an alloy die-casting mold, in which the inner gate is in full contact with the casting, and the material cake and the runner are designed at the center of the casting, so that the distance for the aluminum liquid to reach each position of the mold is basically the same, the filling stroke is significantly shortened, and the overall mold temperature field balance is ensured. The filling time is less than 100ms, and the casting structure is denser.

[0015] The pouring scheme and process method for alloy high-pressure casting according to the present invention have the following advantages: the structural design of central pouring and U-shaped runner is adopted, and the filling distance of the alloy melt is shortened by half compared with the traditional scheme, ensuring that the effective distance for the molten metal to reach each position of the casting is basically the same, reducing the temperature loss during the filling process, and placing slag bags and exhaust ducts in specific areas at the filling end, and designing vacuum centralized exhaust ports at appropriate positions, further reducing the content of pores inside the casting, and the overall pouring and exhaust system is reasonably designed to ensure product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a front projection schematic diagram of a pouring example of an alloy high-pressure casting mold according to an embodiment of the present invention.

[0017] Figure 2 (A), (B), and (C) are respectively an axial view and a front and back schematic diagram of a runner example of an alloy high-pressure casting mold according to an embodiment of the present invention.

[0018] Figure 3 Schematic diagram of the punch structure of the alloy high-pressure casting mold according to an embodiment of the present invention.

[0019] Figure 4 Schematic diagram of the casting window area according to an embodiment of the present invention.

[0020] In the figure: 1-material cake, 2-sprue, 3-U-type runner, 4-ingates, 5-slag bag, 6-casting, 7-12-central exhaust port, 13-exhaust channel, 14-casting window, 20-punch (the bottom surface indicated by the arrow is the contact surface between the punch and the material cake). DETAILED DESCRIPTION

[0021] The exemplary embodiments described below and shown in the drawings are intended to teach the principles of the present invention, so that those skilled in the art can implement and use the present invention in several different environments and for several different applications. Therefore, the scope of protection of the present invention is defined by the attached claims, and the exemplary embodiments are not intended to be, and should not be considered to be, a limiting description of the scope of protection of the present invention. Moreover, for the convenience of description, the sizes of the various parts shown in the drawings are not necessarily drawn according to the actual proportional relationship, and the orientation description, such as the orientation or position relationship indicated by the top, bottom, left, right, top, bottom, etc., are all based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. Any numerical range stated herein is intended to include all sub-ranges contained therein, and the numerical range represented by "value A to value B" refers to a range including the endpoint values ​​A and B. In addition, the term "and / or" in the present invention is only a kind of association relationship describing the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0022] The present invention is described below by taking an aluminum alloy high pressure casting mold particularly suitable for super large aluminum alloy die castings for vehicle bodies as an example. Of course, the alloy high pressure casting mold according to the present invention is not limited to aluminum alloys, but can also be applied to magnesium alloys and other scenes.

[0023] Figure 1An alloy high-pressure casting mold 100 for a high-pressure casting device according to an embodiment of the present invention is schematically shown, comprising a material cake 1, a sprue 2, a runner 3, an ingate 4, a slag bag 5, and centralized exhaust ports 7 to 12 provided with a hydraulic vacuum valve. The cross-sectional area ratio of the sprue 2 to the material cake 1 is 1 / 10 to 1 / 6; the thickness of the ingate 4 is 3.0 to 4.5 mm, and it is connected to the casting 6, and is continuously arranged in a continuous ingate design state rather than a segmented comb-type runner. The cross-sectional area of ​​the punch 20 is 1 / 15 to 1 / 9 of the cross-sectional area of ​​the ingate. At the same time, in the high-speed filling stage, the ingate speed is ensured to be 45 to 70 m / s; the runner 3 is a U-shaped structure, respectively with The sprue 2 is connected to the ingates 4, and the area of ​​the ingates 4 connected to the casting covers more than 3 / 4 of the side wall of the casting window, presenting a central pouring method in which the material cake 1 and the runner (i.e., the sprue 2) are located at the center of the casting; the cross-sectional area of ​​the runner 3 toward the ingates 4 decreases step by step, forming a cross-sectional area convergence state in a roughly conical manner, for example; the runner 3 is connected to the sprue 2 in a vertical manner; all slag bags 5 are arranged at the end of the filling of the casting or the intersection of aluminum liquid; the end of each slag bag continues to be connected to the exhaust channel 13, and each exhaust channel 13 is exhausted in parallel, intersecting in series at a suitable position and connected to the centralized exhaust ports 7 to 12, thereby realizing centralized exhaust that is first connected in parallel and then in series to one place. The effective exhaust area of ​​the centralized exhaust ports 7 to 12 is 25% to 35% of the ingates area (equivalent to the cross-sectional area of ​​the ingates 4), and the exhaust process is controlled by a hydraulic vacuum valve, so that the vacuum degree of the mold cavity during the filling process can be achieved to be ≤80mbar.

[0024] Here, the "centralization" of the centralized exhaust ports 7 to 12 means that after the exhaust channels in front of them are connected in series, centralized exhaust is achieved through the exhaust ports. The gate speed means the alloy melt filling speed at the gate position. The above-mentioned central position basically corresponds to the central position of 1 / 2 of the length and width of the casting and / or its vicinity.

[0025] The high-pressure casting device for the large integrated die-casting mold of the above embodiment includes: a dosing furnace, a punch, a vacuum machine with a vacuum valve, and a control unit. Thus, a component traditionally assembled from multiple parts can be designed into a large integrally formed component.

[0026] The pouring process based on the above high-pressure casting mold is as follows: after the aluminum liquid is added into the pressure chamber through the quantitative furnace, the punch slowly fills the aluminum liquid into the sprue 2. During this process, the vacuum machine evacuates the pressure chamber and the mold cavity, and then the punch further fills the aluminum liquid into the U-shaped cross runner 3 and gradually fills the runner. Before the aluminum liquid approaches the position of the casting ingate 4, the filling starts to switch from slow filling (for example, a slow filling stage of 0 to 0.4 m / s) to high filling (for example, a fast filling stage of 4 to 7 m / s). At the same time, this position point will trigger the vacuum valve to close, and then the punch continues to push the aluminum liquid into the mold cavity through the ingate 4 until the filling is completed. Here, the position point before the aluminum liquid approaches the position of the casting ingate 4 is both the point from slow filling to fast filling and the position point where the vacuum is closed.

[0027] According to the integrated casting casting process and the casting scheme development method of the present invention, the mechanical properties and internal structure of the casting meet the product requirements, and the casting scrap rate is within 10%.

[0028] The mold runner and exhaust system for ultra-large aluminum alloy high-pressure casting according to the present invention has the following advantages: the structural design of central pouring and U-shaped runner is adopted, and the filling distance of aluminum liquid is shortened by half compared with the traditional scheme, ensuring that the effective distance for aluminum liquid to reach various positions of the casting is basically the same, reducing the temperature loss during the filling process, and placing slag bags and exhaust ducts in specific areas at the filling end, and designing vacuum centralized exhaust ports at appropriate positions, further reducing the content of pores inside the casting, and the overall pouring and exhaust system is reasonably designed, ensuring that the product appearance and mechanical properties meet the product requirements.

[0029] In the description of this application, "multiple" means two or more than two, unless otherwise clearly specified and specifically defined. Unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. The above embodiments are only for illustrating the technical concept and features of the present invention. The purpose is to enable people familiar with this technical field to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An alloy high pressure casting mold, characterized in that: Used for casting an integrated die casting having a casting window area, comprising: a straight runner (2), a cross runner (3), an ingate (4), a slag bag (5), and a centralized exhaust port (7-12) provided with a vacuum valve, wherein the cross runner (3) and the straight runner (2) arranged at the center of the casting are connected to each other in a perpendicular manner, the cross runner (3) is connected to the ingate (4) in a manner in which the cross-sectional area decreases toward the ingate (4), the slag bag (5) is arranged at the filling end of the casting or at the intersection of the alloy melt, and an exhaust channel (13) is connected to the end of each slag bag. The exhaust channels (13) are connected in parallel and in series to the centralized exhaust port (7-12) at the intersection position. The runner (3) is in a U-shaped structure. The ingates (4) are in a continuous ingates structure. The area of ​​the ingates (4) connected to the casting covers more than 3 / 4 of the side wall of the casting window. The ingates (4) are formed on the entire outer peripheral side of the U-shaped structure of the runner (3). The runner (3) forms a cross-sectional area convergence structure in a conical manner. The effective exhaust area of ​​the centralized exhaust port is 25%-35% of the ingates area.

2. The alloy high pressure casting mold according to claim 1, characterized in that: The thickness of the inner gate (4) is between 3.0 and 4.5 mm.

3. A high pressure casting device, characterized in that: A dosing furnace, a punch, a vacuum machine with a vacuum valve, a control unit and an alloy high-pressure casting mold according to any one of claims 1 to 2 are provided, wherein the cross-sectional area of ​​the punch is 1 / 15 to 1 / 9 of the cross-sectional area of ​​the inner gate.

4. A method for casting an alloy casting, characterized in that: The pouring method for the high-pressure casting device as claimed in claim 3 comprises the following steps: when the alloy melt is added into the pressure chamber through the quantitative furnace, the punch fills the alloy melt into the sprue (2), during which the pressure chamber and the cavity are evacuated, and then the punch further fills the alloy melt into the U-shaped cross runner (3) and gradually fills the runner, and the filling speed is accelerated before the alloy melt approaches the position of the inner gate (4). At the same time, the vacuum valve is triggered to close at this position, and then the punch continues to push the alloy melt into the cavity through the inner gate (4) until the filling is completed.

5. The method for casting an alloy casting according to claim 4, characterized in that: Using the control unit to control the exhaust process of the vacuum valve in such a way that the vacuum degree of the mold cavity during the filling process meets ≤80mbar; And / or, in the stage of accelerating the filling speed, the gate speed is 45-70 m / s and the filling time is less than 100 ms.

6. The method for casting an alloy casting according to any one of claims 4 to 5, characterized in that: Used for casting an aluminum alloy car body; and / or, the cross-sectional area ratio of the sprue (2) to the material cake (1) at the center of the casting is 1 / 10 to 1 / 6.

Images