Deformation-resistant mechanisms and injection molds for planar plastic products

Abstract

This utility model discloses an anti-deformation mechanism for planar plastic parts and an injection mold. The anti-deformation mechanism includes a moving mold; a moving core is provided in the middle of the moving mold; a B-groove is provided on the moving core, which cooperates with the A-groove on the fixed core in the middle of the fixed mold to form a cavity; multiple positioning post groups are spaced apart along the length of the moving core in the B-groove, and each positioning post group includes multiple positioning posts spaced apart along the width of the moving core, so that the positioning posts are arranged in a matrix in the B-groove. During the product cooling and shaping process, the positioning posts can restrict the movement of the product in the cavity, prevent local shrinkage of the product, and thus make the product surface flat after mold opening, without warping or bending, improving product quality and ensuring product consistency; moreover, the positioning posts can also play a role in venting, making the overall temperature difference of the product uniform, avoiding the impact of temperature difference on the product appearance and performance, and improving the product qualification rate.

Description

Technical Field

[0001] This utility model belongs to the field of injection mold technology, specifically relating to an anti-deformation mechanism for planar plastic parts and an injection mold. Background Technology

[0002] Injection molding is a method of shaping industrial products. Products are typically made using rubber injection molding and plastic injection molding. The advantages of injection molding are high production speed and efficiency, automated operation, a wide variety of colors and shapes, shapes ranging from simple to complex, sizes ranging from large to small, precise product dimensions, easy product updates and replacements, and the ability to create complex-shaped parts. Injection molding is suitable for mass production and molding of complex-shaped products.

[0003] During the injection molding process of planar plastic parts, warping defects of varying degrees can occur after molding due to factors such as molecular orientation effects, uneven volume shrinkage rates in different material regions, and uneven cooling. Currently, there is no ideal solution for this; the only recourse is to use shaping fixtures to correct the deformation after molding. However, this post-molding method is extremely time-consuming, increases labor and fixture costs, and cannot guarantee product consistency. Especially for products with high surface finish requirements, repeated handling and handling can easily cause scratches and dents, resulting in low dimensional accuracy and poor appearance quality, thus reducing the product yield. Summary of the Invention

[0004] To overcome the aforementioned problems in the prior art, this utility model provides a deformation-resistant mechanism for planar plastic parts. This mechanism features a moving core on a moving mold, with a matrix of positioning pins on the moving core. During the cooling and solidification process, the positioning pins restrict the movement of the product within the cavity, preventing localized shrinkage. This results in a smooth product surface after mold opening, free from warping or bending, improving product quality and ensuring consistency. Furthermore, the positioning pins also act as venting devices, ensuring uniform temperature distribution across the product and mitigating the impact of temperature variations on appearance and performance, thus increasing the product yield. Correspondingly, this utility model also provides an injection mold employing the aforementioned deformation-resistant mechanism.

[0005] For the anti-deformation mechanism, the technical solution of this application is as follows: An anti-deformation mechanism for planar plastic parts includes a moving mold; a moving core is provided in the middle of the moving mold; a B-shaped groove is provided on the moving core; the B-shaped groove cooperates with the A-shaped groove on the fixed core in the middle of the fixed mold to form a cavity during use; multiple positioning post groups are provided at intervals along the length direction of the moving core in the B-shaped groove, and the positioning post groups include multiple positioning posts distributed at intervals along the width direction of the moving core, so that the positioning posts are arranged in a matrix in the B-shaped groove.

[0006] Compared with existing technologies, the anti-deformation mechanism for planar plastic parts in this application sets a moving core on the moving mold and sets a matrix of positioning pins on the moving core. This allows the positioning pins to limit the movement of various parts of the product during the cooling and shaping process, thereby restricting the product's movement within the cavity and preventing local shrinkage, i.e., pulling the product to prevent deformation. This results in a smooth product surface after mold opening, free from bending and warping, improving product quality and ensuring product consistency. Moreover, the positioning pins can also change the flow direction and speed of the molten plastic during injection molding, playing a role in venting and making the overall temperature difference of the product uniform. This avoids the impact of temperature difference on the product's appearance and performance, and improves the product qualification rate.

[0007] As an optimization, in the aforementioned anti-deformation mechanism for planar plastic parts, the height of the positioning pins is no greater than 1 / 3 of the product thickness. During injection molding, the positioning pins are inserted into the product; if the positioning pins are too high, the corresponding holes on the back of the product will be too deep, thus affecting the product's strength. Furthermore, the diameter of the positioning pins can be 2-5mm. If the positioning pins are too thin, they cannot effectively limit the movement; if they are too thick, the holes left on the back of the product will be larger, thus affecting the overall strength of the product. Experiments show that a positioning pin diameter of 2-5mm is optimal. Furthermore, the spacing between two adjacent positioning pins can be 0.1-0.3 times the product width. Generally, warping and deformation are prone to occur at the product edges. Therefore, in actual design, the spacing between positioning pins located at the edges can be designed to be relatively small, while the spacing between positioning pins located in the middle can be designed to be relatively large, i.e., the positioning pins are arranged in an irregular matrix on the moving core.

[0008] As an optimization, in the aforementioned anti-deformation mechanism for planar plastic parts, the positioning post penetrates the moving core and has a limiting block at the bottom; the limiting block is fixed inside the moving core. This results in a simple structure and convenient assembly.

[0009] Regarding injection molds, the technical solution of this application is as follows: An injection mold includes a fixed mold plate, a hot runner plate, a fixed mold, a moving mold, mold feet, and a moving mold plate arranged sequentially. An ejector plate is provided between the moving mold and the moving mold plate, and the ejector plate has an ejection mechanism for ejecting the product out of the injection mold. The fixed mold and the moving mold are arranged opposite each other. A shaped core is provided in the center of the fixed mold, and an A-shaped groove is formed on the shaped core. Correspondingly, a moving core is provided in the center of the moving mold, and a B-shaped groove is formed on the moving core. In the mold-closed state, the A-shaped groove and the B-shaped groove cooperate to form a cavity. Multiple locating post groups are spaced apart along the length direction within the B-shaped groove. Each locating post group includes multiple locating posts spaced apart along the width direction, so that the locating posts are arranged in a matrix within the B-shaped groove.

[0010] Compared with the prior art, the injection mold of this application is equipped with a specific anti-deformation mechanism, which can limit the movement of various parts of the product during the cooling and solidification process, thereby preventing the product from shrinking inward and deforming. This results in a smooth product surface after mold opening, without bending or warping, improving product quality, ensuring product consistency, and increasing the product qualification rate.

[0011] As an optimization, in the aforementioned injection mold, the height of the positioning pins is no greater than 1 / 3 of the product thickness. During product injection molding, the positioning pins are inserted into the product; if the positioning pins are too high, the corresponding holes formed on the back of the product will be too deep, thus affecting the product's strength. Furthermore, the diameter of the positioning pins can be 2–5 mm. If the positioning pins are too thin, they cannot effectively limit the movement; if the positioning pins are too thick, the holes left on the back of the product will be larger, thus affecting the overall strength of the product. Experiments show that a positioning pin diameter of 2–5 mm is optimal. Furthermore, the spacing between two adjacent positioning pins can be 0.1–0.3 times the product width.

[0012] As an optimization, in the aforementioned injection mold, the positioning post penetrates the moving core and has a limiting block at the bottom; the limiting block is fixed inside the moving core. This results in a simple structure and convenient assembly.

[0013] As an optimization, in the aforementioned injection mold, each of the four corners of the moving core has a protrusion, and correspondingly, each of the four corners of the fixed core has a groove; in the mold-closed state, each protrusion is embedded in the corresponding groove. This allows the surfaces of the fixed core and the moving core to fit together well when the mold is closed. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the anti-deformation mechanism of the planar plastic part product in this application; Figure 2 This is a schematic diagram of the fixed mold structure in this application; Figure 3This is a schematic diagram of the structure of the injection mold in this application; Figure 4 This is an assembly diagram of the positioning post and the moving core in this application; Figure 5 This is a structural schematic diagram of the auxiliary instrument storage box in the implementation case of this application; Figure 6 a is a secondary instrument storage box manufactured using existing injection mold technology. Figure 6 b is a secondary instrument storage box produced using the injection mold of this application.

[0015] The markings in the attached diagram are as follows: 1-Fixed mold fixing plate; 2-Hot runner plate; 3-Fixed mold; 31-Fixed core; 301-Type A groove; 302-Groove; 4-Moving mold; 41-Moving core; 411-Protrusion; 401-Type B groove; 5-Mold foot; 6-Moving mold fixing plate; 7-Ejector plate; 8-Positioning pin; 81-Limiting block. Detailed Implementation

[0016] The present application will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present application.

[0017] During the injection molding of planar plastic parts, warping defects of varying degrees can occur after molding due to factors such as molecular orientation effects, uneven volume shrinkage rates in different material regions, and uneven cooling. Currently, there is no satisfactory solution to this problem. Therefore, the applicant provides an injection mold that improves the structure of the moving mold 4. A moving core 41 is set in the middle of the moving mold 4, and positioning pins 8 are set on the moving core 41. These positioning pins are used to limit the movement of various parts of the product during the cooling and solidification process, thereby restricting the product's movement within the cavity and preventing deformation. The number, size, and spacing of the positioning pins 8 are arranged reasonably according to the product size and can be referenced using mold flow.

[0018] See Figures 1 to 3 The injection mold of this application includes a fixed mold fixing plate 1, a hot runner plate 2, a fixed mold 3, a moving mold 4, mold feet 5, and a moving mold fixing plate 6 arranged sequentially. An ejector plate 7 is provided between the moving mold 4 and the moving mold fixing plate 6. The ejector plate 7 is provided with an ejection mechanism for ejecting the product out of the injection mold. The fixed mold 3 and the moving mold 4 are arranged opposite to each other. A mold core 31 is provided in the middle of the fixed mold 3, and an A-type groove 301 is formed on the mold core 31. Correspondingly, a moving mold core 41 is provided in the middle of the moving mold 4, and a B-type groove 401 is formed on the moving mold core 41. In the mold closed state, the A-type groove 301 and the B-type groove 401 cooperate with each other to form a cavity. Multiple positioning post groups are arranged at intervals along the length direction in the B-type groove 401. The positioning post groups include multiple positioning posts 8 distributed at intervals along the width direction, so that the positioning posts 8 are arranged in a matrix in the B-type groove 401.

[0019] Furthermore, the height of the positioning post 8 (i.e., the length of the positioning post 8 extending beyond the bottom of the B-type groove 401) is no greater than 1 / 3 of the product thickness; the diameter of the positioning post 8 is 2-5mm; and the spacing between two adjacent positioning posts 8 is 0.1-0.3 times the product width.

[0020] See Figure 4 The positioning post 8 penetrates the moving core 41 and has a limiting block 81 at its bottom; the limiting block 81 is fixed inside the moving core 41. This results in a simple structure and convenient assembly. During assembly, corresponding through holes and mounting grooves are made inside the moving core 41, the positioning post 8 is inserted into the through hole, and the limiting block 81 is positioned in the mounting groove to fix it in place.

[0021] See Figure 1 and Figure 2 The moving core 41 has a protrusion 411 on each of its four corners, and the fixed core 31 has a groove 302 on each of its four corners. In the mold closing state, each protrusion 411 is embedded in the corresponding groove 302, so that the surfaces of the fixed core 31 and the moving core 41 can fit together well.

[0022] Implementation Case: In this case, the injection mold described in this application is used to produce automotive interior plastic parts—the auxiliary instrument panel storage box (see [link]). Figure 5 In the injection mold, the height of the positioning pin 8 is 1 / 4 of the product thickness and the diameter is 2mm; the distance between two adjacent positioning pins 8 is 0.1 to 0.3 of the product width. The distance between two positioning pins 8 at different positions is different, that is, the positioning pins 8 are arranged in an irregular matrix on the moving core 41 (the distance between positioning pins 8 located at the edge is relatively smaller, and the distance between positioning pins 8 located in the middle is relatively larger).

[0023] During production, the injection mold is installed on the injection molding machine, and the injection material is PC+ABS+TPU. Then, the injection mold is closed, the injection molding machine is started, and molten plastic is injected into the cavity through the gating system. The molten plastic flows within the cavity, and its flow direction and speed change when it passes the positioning pins 8, which helps to vent air. When the product cools and solidifies within the cavity, the presence of the positioning pins 8 restricts the product's movement within the cavity, controlling local shrinkage (one-time shrinkage for PP+ABS hard plastic and one-time shrinkage for TPU soft plastic), allowing the product to withstand the time and temperature at which it is prone to deformation within the cavity. After the product cools, the injection mold opens, the ejection mechanism is activated, and the product is ejected. At this point, the product surface is generally flat, without bending or warping deformation (see...). Figure 6 b). The surface of the automotive interior plastic parts—specifically the secondary instrument cluster storage box—produced using existing injection molds exhibits noticeable bending, such as... Figure 6 As shown in a.

[0024] The foregoing general description of the utility model and its specific embodiments should not be construed as limiting the technical solution of the utility model. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the utility model, to form other technical solutions within the protection scope of this application.

Claims

1. A deformation-resistant mechanism for planar plastic parts, characterized in that: The system includes a moving mold (4); a moving core (41) is provided in the middle of the moving mold (4); a B-shaped groove (401) is provided on the moving core (41); the B-shaped groove (401) cooperates with the A-shaped groove (301) on the fixed core (31) in the middle of the fixed mold (3) to form a cavity; a plurality of positioning post groups are provided in the B-shaped groove (401) along the length direction of the moving core (41), and the positioning post group includes a plurality of positioning posts (8) distributed along the width direction of the moving core (41), so that the positioning posts (8) are arranged in a matrix in the B-shaped groove (401).

2. The anti-deformation mechanism for planar plastic parts according to claim 1, characterized in that: The height of the positioning post (8) is no more than 1 / 3 of the product thickness.

3. The anti-deformation mechanism for planar plastic parts according to claim 2, characterized in that: The diameter of the positioning post (8) is 2-5 mm.

4. The anti-deformation mechanism for planar plastic parts according to claim 2, characterized in that: The distance between two adjacent positioning posts (8) is 0.1 to 0.3 times the width of the product.

5. The anti-deformation mechanism for planar plastic parts according to claim 4, characterized in that: The positioning post (8) passes through the moving core (41) and has a limiting block (81) at the bottom; the limiting block (81) is fixed inside the moving core (41).

6. An injection mold, comprising a fixed mold fixing plate (1), a hot runner plate (2), a fixed mold (3), a moving mold (4), mold feet (5), and a moving mold fixing plate (6) arranged sequentially; an ejector plate (7) is provided between the moving mold (4) and the moving mold fixing plate (6), and an ejection mechanism is provided on the ejector plate (7) for ejecting the product out of the injection mold; the fixed mold (3) and the moving mold (4) are arranged opposite to each other; characterized in that: The fixed mold (3) has a fixed core (31) in the middle, and an A-type groove (301) is provided on the fixed core (31). Correspondingly, the moving mold (4) has a moving core (41) in the middle, and a B-type groove (401) is provided on the moving core (41). In the mold closed state, the A-type groove (301) and the B-type groove (401) cooperate with each other to form a cavity. Multiple positioning post groups are provided in the B-type groove (401) along the length direction. The positioning post group includes multiple positioning posts (8) distributed along the width direction, so that the positioning posts (8) are arranged in a matrix in the B-type groove (401).

7. The injection mold according to claim 6, characterized in that: The height of the positioning post (8) is no more than 1 / 3 of the product thickness.

8. The injection mold according to claim 7, characterized in that: The diameter of the positioning post (8) is 2 to 5 mm; the distance between two adjacent positioning posts (8) is 0.1 to 0.3 times the width of the product.

9. The injection mold according to claim 8, characterized in that: The positioning post (8) passes through the moving core (41) and has a limiting block (81) at the bottom; the limiting block (81) is fixed inside the moving core (41).

10. The injection mold according to claim 6, characterized in that: The four corners of the fixed core (31) are respectively provided with a groove (302), and the four corners of the moving core (41) are respectively provided with a protrusion (411); in the mold closing state, each protrusion (411) is embedded in the corresponding groove (302).

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