A magnesium alloy screw column structure for reducing shrinkage cracks of a vehicle-mounted screen support

Abstract

The utility model discloses a kind of magnesium alloy screw column shrinkage crack structures for reducing vehicle-mounted screen support, belong to metal die casting technical field.The method mainly includes: in mould design, set up cylindrical core in screw column cavity position, make the screw column after forming hollow structure, to reduce thermal volume;Cooling water channel is opened in the cylindrical core inside and is implemented forced cooling, so that screw column inside solidifies first, realize the sequential solidification from inside to outside;While screw column root and substrate connecting place are additionally provided with radial reinforcing rib, to enhance structural rigidity and assist feeding.This application changes the solidification process of screw column fundamentally through the synergistic effect of "hollow design, internal strong cold, external reinforcement", effectively eliminates the shrinkage cavity and shrinkage crack defects generated by magnesium alloy screw column due to insufficient feeding, significantly improves the yield and mechanical energy of product.

Description

Technical Field

[0001] This utility model relates to the field of metal die casting technology, specifically to a structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets. Background Technology

[0002] Magnesium alloys are widely used in consumer electronics, the automotive industry, and other fields due to their advantages such as low density, high specific strength, and good vibration damping. Die casting is the mainstream process for manufacturing magnesium alloy parts. However, magnesium alloys have a wide solidification range and a large solidification shrinkage rate, making them prone to casting defects such as shrinkage cavities and porosity during the die casting process.

[0003] Boss studs, a common connection structure, are characterized by a wall thickness much greater than that of the substrate they connect to, forming a typical "hot spot." During solidification, the hot spot region cools and shrinks last, but cannot receive sufficient melt replenishment, resulting in shrinkage cavities inside. In severe cases, this can even extend to the surface, forming visible shrinkage cracks. This not only reduces the mechanical strength of the boss stud (such as tensile and torque resistance) but also affects the product's appearance quality and yield rate.

[0004] Traditional methods for solving screw post shrinkage cracks mainly include: 1. Reduce the diameter or wall thickness of the screw post: But this would sacrifice structural strength, which contradicts the original design intention.

[0005] 2. Add ejector pins or cooling channels: For deep cavities or dense groups of screw posts, conventional cooling is often ineffective and cannot directly reach the center of the hot spot.

[0006] 3. Optimize die casting parameters (such as increasing holding pressure and time): The effect is limited and may cause other problems such as flash and sticking to the mold.

[0007] Therefore, there is a need to provide a structure that reduces shrinkage cracks in the magnesium alloy screw posts of the vehicle screen bracket. Utility Model Content

[0008] To address the problems existing in the prior art, this utility model provides a structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets, aiming to improve and solve the aforementioned technical problems.

[0009] To achieve the above objectives, this utility model provides the following technical solution: a structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets, comprising: a die-cast magnesium alloy substrate and screw posts disposed thereon and formed by casting through a cavity mold; the screw posts are hollow structures with non-penetrating cavities inside; multiple radial reinforcing ribs are provided at the connection between the root of the screw post and the substrate; the interior of the cavity is configured as a cylindrical core, and the interior of the cylindrical core is hollow to serve as a cooling water channel, which is connected to the cooling system of the mold.

[0010] Preferably, the number of reinforcing ribs is three, and they are evenly distributed along the circumference of the screw post.

[0011] Preferably, the cooling water channel is a straight-hole type, which is arranged along the axial center of the cylindrical core.

[0012] Preferably, the cooling water channel is connected to the mold's cooling system via a connecting medium inlet and a medium outlet for circulating cooling of the cylindrical core.

[0013] Preferably, the cooling medium inside the cooling water channel is cooling water.

[0014] In summary, this utility model provides a structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets. The beneficial effects of this patent are as follows: 1. Significantly reduce or eliminate defects: By combining "hollow core + strong point cooling", the solidification mode of the screw column is completely changed, making it the first solidification area instead of the most difficult area to compensate for shrinkage, thus fundamentally eliminating the generation of shrinkage cavities and shrinkage cracks.

[0015] 2. Improved mechanical performance: The hollow design reduces internal defects and ensures the density of the material; the reinforcing ribs significantly enhance the rigidity and strength of the structure, and the overall performance is superior to that of a solid but defective screw post.

[0016] 3. No additional processes: All measures are completed in the mold design and die-casting process, eliminating the need for subsequent machining or heat treatment to repair defects, thus improving production efficiency and reducing overall costs.

[0017] 4. Strong applicability: The principle of this method is clear and applicable to magnesium alloy screw posts of various specifications. It is especially effective for large and densely distributed groups of screw posts. Attached Figure Description

[0018] Figure 1 A schematic diagram of a magnesium alloy substrate and screw post cast together; Figure 2 A schematic diagram of a die-cast part with hollow screw posts and reinforcing ribs; Figure 3 for Figure 2 The top view shows the layout of the radial stiffeners; Figure 4 This is a schematic diagram of the structure and cooling water channels of the mold core. In the diagram: 1. Magnesium alloy substrate; 2. Screw post; 3. Cavity; 4. Reinforcing rib; 5. Cylindrical core; 6. Cooling channel. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] like Figures 1 to 4 As shown: This invention relates to a structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets. It addresses the issue that during the casting and solidification process of magnesium alloy screw posts, the hot spot area cools and shrinks last, failing to receive sufficient melt replenishment, thus generating shrinkage cavities internally, and in severe cases, even extending to the surface to form visible shrinkage cracks. This not only reduces the mechanical strength of the screw post (such as tensile and torque resistance) but also affects the product's appearance quality and yield rate. The technical structure adopted in this patent includes: a die-cast magnesium alloy substrate 1 and a screw post 2 formed thereon by casting through a cavity mold; the screw post 2 is a hollow structure with a non-penetrating cavity 3 inside; the hollow design can transform the huge solid hot spot into a relatively thin annular wall thickness hot spot, fundamentally reducing the total amount of molten metal that needs to be fed. The root of the screw post 2 is provided with multiple radial reinforcing ribs 4 at the connection between it and the base plate 1. The reinforcing ribs 4 have a dual function: to improve the tensile and torsional strength of the screw post and to compensate for the rigidity loss that may be caused by the hollow design; the reinforcing ribs 4 themselves can act as "shrinkage channels" to more effectively transfer the holding pressure to the hot spot area at the root of the screw post in the later stage of solidification, and their additional surface area also acts as heat sinks to accelerate the cooling of this critical area.

[0021] The cavity 3 is internally configured with a cylindrical core 5, which is hollow and serves as a cooling channel 6 connected to the mold's cooling system. Specifically, during the die-casting process, a cooling medium (such as water or oil) is continuously introduced into this cooling channel to force-cool the core. This "spot cooling" technology can quickly remove heat from the core area inside the screw post, causing it to solidify first, thus achieving sequential solidification from the inside out, which is beneficial for shrinkage compensation.

[0022] In at least one embodiment, the number of reinforcing ribs 4 is three, and they are evenly distributed along the circumference of the screw post 2.

[0023] In at least one embodiment, the cooling water channel 6 is a straight-hole water channel, which is arranged along the axial center of the cylindrical core 5.

[0024] In at least one embodiment, the cooling channel 6 is connected to the cooling system of the mold via a connecting medium inlet 7 and a medium outlet 8 for circulating cooling of the cylindrical core 5.

[0025] In at least one embodiment, the cooling medium inside the cooling channel 6 is cooling water.

[0026] 1. Structural design: The original solid screw post with a diameter of 8mm is replaced with a hollow screw post 2 with an outer diameter of 8mm and an inner diameter of 4mm; at the root of the screw post 2, three evenly distributed radial reinforcing ribs 4 are added. The reinforcing ribs 4 are 3mm high, 1.5mm long, and 0.8mm thick at the root.

[0027] 2. Mold and cooling design: A cylindrical core 5 is machined and placed in the cavity mold in advance. By injecting magnesium alloy melt, a screw post 2 is formed between the mold and the cylindrical core 5. The cylindrical core 5 is inside the screw post 2, so that a cavity 3 is formed inside the screw post 2.

[0028] A 2.5mm diameter cooling channel 6 is drilled in the center of the cylindrical core 5 to form a "point cooling" system. The cooling channel 6 is connected to the mold's cooling circulation system to ensure that high-pressure, high-flow-rate cooling water can flow directly through the interior of the core 5.

[0029] 3. Die-casting process: Standard AZ91D magnesium alloy raw material is used. Die-casting process parameters such as injection speed and pressure are set as usual.

[0030] Key point: Ensure that the cooling water circuit of the cylindrical core 5 is open throughout the die-casting cycle to provide powerful cooling for the core.

[0031] The embodiments described in this utility model are for illustrative purposes only and do not constitute a limitation on the scope of the claims. Other substantially equivalent substitutions that can be conceived by those skilled in the art are all within the protection scope of this utility model.

Claims

1. A structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets, characterized in that, include: A die-cast magnesium alloy substrate (1) and a screw post (2) formed thereon by casting through a cavity mold; the screw post (2) is a hollow structure with a non-penetrating cavity (3) inside; multiple radial reinforcing ribs (4) are provided at the connection between the root of the screw post (2) and the substrate (1); the cavity (3) is provided with a cylindrical core (5), the cylindrical core (5) is hollow inside to serve as a cooling water channel (6), and the cooling water channel (6) is connected to the cooling system of the mold.

2. The structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets according to claim 1, characterized in that, The number of the reinforcing ribs (4) is 3, and they are evenly distributed along the circumference of the screw post (2).

3. The structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets according to claim 1, characterized in that, The cooling water channel (6) is a straight hole type water channel, which is set along the axial center of the cylindrical core (5).

4. The structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets according to claim 1, characterized in that, The cooling channel (6) is connected to the cooling system of the mold via a connecting medium inlet (7) and a medium outlet (8) for circulating cooling of the cylindrical core (5).

5. The structure for reducing shrinkage cracks in magnesium alloy screw posts of vehicle screen brackets according to claim 1, characterized in that, The cooling medium inside the cooling water channel (6) is cooling water.

Images