Shrink resistant injection molded parts and distortion resistant molds

Abstract

The application relates to the technical field of plastic structure design, in particular to an anti-shrink injection molded part and a deformation-resistant mold, the anti-shrink injection molded part comprising a main body part, a supporting part and a screw column. The supporting part is fixedly arranged on the main body part; the screw column is fixedly arranged on the main body part close to the supporting part; a side wall of the supporting part close to the screw column is arranged into an arc-shaped side wall concentric with the outer circumferential surface of the screw column; and a spacing L is arranged between the arc-shaped side wall and the outer circumferential surface of the screw column, wherein L = R - r, the radius of the arc-shaped side wall is R, the radius of the outer circumferential surface of the screw column is r, and 0.75 mm <= L <= 2 mm. The anti-shrink injection molded part provided by the application avoids direct connection between the screw column and the arc-shaped side wall by arranging the side wall of the supporting part close to the screw column into an arc-shaped side wall concentric with the outer circumferential surface of the screw column and arranging a spacing L between the arc-shaped side wall and the outer circumferential surface of the screw column, effectively reduces the structure with excessively large local material thickness, and thus solves the appearance and structural defect problems caused by uneven shrinkage.

Description

Technical Field

[0001] This application relates to the field of plastic structure design technology, and more specifically, to anti-shrinkage injection molded parts and anti-deformation molds. Background Technology

[0002] With the widespread application of injection molding technology in electronic device manufacturing, injection molded housings are widely used to support and protect internal electronic components, such as PCBAs (Printed Circuit Board Assemblies). To achieve secure fixing of the PCBA (or to securely fix two injection molded housings together), screw posts are typically installed on the inner wall of the injection molded housing, using screws to lock the PCBA into the housing (or to fix two injection molded housings together using screws). However, with the trend towards miniaturization and thinner designs, the overall structural space of electronic devices is becoming increasingly compact, severely limiting the space within the injection molded housing to accommodate the PCBA. In this context, the design location of the screw posts is often forced to be close to the edge area of ​​the injection molded housing. When the screw post is placed in such a restricted area, if it is directly connected to the edge shell, a structure with excessive local material thickness will be formed at the connection point. This will cause uneven shrinkage of the plastic material during cooling, resulting in appearance and structural defects such as surface shrinkage and shrinkage marks. Conversely, if the screw post and the edge shell are kept at a certain distance (e.g., 0.05mm-2mm) and do not overlap directly, the mold structure between the two needs to form a narrow gap. This will cause the steel core in the mold to have a thin wall shape in this area, reducing mechanical strength. During long-term injection molding production, it is prone to deformation or damage, affecting mold life and product yield. Utility Model Content

[0003] The purpose of this application is to provide a shrinkage-resistant injection molded part and a deformation-resistant mold, which avoids surface shrinkage defects to a certain extent.

[0004] To achieve the above objectives, in a first aspect, this application provides a shrink-resistant injection molded part, comprising: Main body; The support portion is fixedly mounted on the main body portion; A screw post is fixedly disposed on the main body near the support portion. The side wall of the support portion near the screw post is configured as an arc-shaped side wall concentric with the outer circumferential surface of the screw post. A distance L is provided between the arc-shaped side wall and the outer circumferential surface of the screw post, where L=Rr, the radius of the arc-shaped side wall is R, the radius of the outer circumferential surface of the screw post is r, and 0.75mm≤L≤2mm.

[0005] In an optional embodiment, an internal reinforcing rib is further included, which is fixedly disposed on the main body and located between the support and the screw post. The internal reinforcing rib is fixedly connected to the outer peripheral surface of the arc-shaped sidewall and the screw post.

[0006] In an optional embodiment, an external reinforcing rib is further included, which is fixedly disposed on the outer peripheral surface of the screw post and connects the outer peripheral surface of the screw post and the main body.

[0007] In an optional embodiment, at least two external reinforcing ribs are provided, and the at least two external reinforcing ribs are distributed circumferentially around the screw post.

[0008] In an optional embodiment, the support portion is further provided with a straight sidewall connected to the arc-shaped sidewall, and the connection between the straight sidewall and the arc-shaped sidewall is provided with a rounded corner.

[0009] Secondly, this application provides an anti-deformation mold for manufacturing an anti-shrinkage injection molded part as described in any of the foregoing embodiments. The anti-deformation mold includes a mold body, which has a first cavity for forming the main body portion, a second cavity for forming the support portion, and a third cavity for forming the screw post. A first steel core is provided between the second cavity and the third cavity to define the arcuate sidewall and the outer peripheral surface of the screw post. The minimum thickness of the first steel core is L.

[0010] The shrinkage-resistant injection molded part provided in this application, by setting the side wall of the support part near the screw post as an arc-shaped side wall concentric with the outer peripheral surface of the screw post, and setting a distance L between the arc-shaped side wall and the outer peripheral surface of the screw post, avoids direct connection between the screw post and the arc-shaped side wall, effectively reduces the structure of excessive local material thickness, and thus solves the problem of appearance and structural defects caused by uneven shrinkage.

[0011] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of the structure from one perspective of one embodiment of the anti-shrinkage injection molded part provided in this application; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 A two-view structural schematic diagram of one embodiment of the anti-shrinkage injection molded part provided in this application; Figure 4 for Figure 3 A magnified view of a section at point B in the middle; Figure 5 This is a partially enlarged view of one embodiment of the anti-deformation mold provided in this application.

[0014] icon: 100 - Main body; 110 - Supporting part; 112 - Arc-shaped sidewall; 114 - Straight sidewall; 116 - Rounded corner; 120 - Screw post; 130 - Internal reinforcing rib; 140 - External reinforcing rib; 300 - Anti-deformation mold; 310 - First cavity; 320 - Second cavity; 330 - Third cavity; 350 - First steel core. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0017] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0018] In a first aspect, embodiments of this application provide a shrink-resistant injection molded part, including a main body 100, a support 110, and a screw post 120.

[0019] like Figure 1 and Figure 2 As shown, the support portion 110 is fixedly disposed on the main body portion 100; for example, the support portion 110 and the main body portion 100 are integrally molded and fixed by injection molding.

[0020] The screw post 120 is fixedly disposed on the main body 100 near the support 110; for example, the support 110 and the screw post 120 are integrally molded and fixed by injection molding.

[0021] For example, the main body 100 is the main part of the shrink-proof injection molded part. If the shrink-proof injection molded part is a shell, the main body 100 is the main shell part, and the support part 110 can be the outer edge wall or other outer wall of the main shell, or other plate structure.

[0022] For example, such as Figure 2 or Figure 4 As shown, the support part 110 is a plate structure that extends along a straight line.

[0023] like Figure 2 As shown, the side wall of the support 110 near the screw post 120 is configured as an arc-shaped side wall 112 concentric with the outer peripheral surface of the screw post 120.

[0024] like Figure 3 and Figure 4 As shown, a distance L is provided between the arc-shaped sidewall 112 and the outer peripheral surface of the screw post 120, where L=Rr, the radius of the arc-shaped sidewall 112 is R, the radius of the outer peripheral surface of the screw post 120 is r, and 0.75mm≤L≤2mm.

[0025] With the pursuit of miniaturization and thinness in electronic devices, and the increasingly compact space of injection-molded housing structures, the design position of the screw post 120 is often forced to be close to the edge area. If the screw post 120 is directly connected to the edge housing, it will create a structure with excessive local material thickness at the connection point. This structure will cause uneven shrinkage of the plastic material during cooling, leading to appearance and structural defects such as surface shrinkage and shrinkage marks. However, by setting the side wall of the support part 110 near the screw post 120 as an arc-shaped side wall 112 concentric with the outer peripheral surface of the screw post 120, and setting a distance L between the arc-shaped side wall 112 and the outer peripheral surface of the screw post 120, the direct connection between the screw post 120 and the arc-shaped side wall 112 is avoided, effectively reducing the structure with excessive local material thickness, thereby solving the appearance and structural defects caused by uneven shrinkage.

[0026] If a certain distance is maintained between the screw post 120 and the edge shell without a reasonable structural design, a narrow gap will form between them in the mold structure, causing the steel core in the mold to have a thin wall in that area, reducing its mechanical strength. During long-term injection molding production, the thin-walled steel core is prone to deformation or damage, affecting mold life and product yield. This application sets a reasonable spacing L, avoiding the deformation problem caused by insufficient steel core wall thickness due to an excessively small spacing, ensuring the strength of the mold structure, extending the mold's service life, and improving the product yield.

[0027] If the screw post 120 is completely separated from the edge shell with a gap of less than 0.75mm, the mold needs to machine an extremely thin steel core at this point, which is prone to fatigue deformation or even fracture under long-term high temperature and high pressure impact. A steel core thickness below 0.6mm enters a high-risk zone; this application avoids this critical value. In this application, the minimum spacing is limited to 0.75mm, ensuring that the mold steel core has sufficient lateral cross-sectional area and heat dissipation capacity in this area, improving structural rigidity and durability, and achieving a dual guarantee of mold manufacturability and production stability. Furthermore, if the screw post 120 is completely separated from the support wall with a gap of less than 0.75mm, the small gap may cause the mold slider or inclined ejector mechanism to experience significant resistance during demolding, potentially causing surface damage to the product, such as scratches or whitening, reducing the product yield.

[0028] like Figure 2 and Figure 4 As shown, in one embodiment, the anti-shrinkage injection molded part further includes an internal reinforcing rib 130 fixedly disposed on the main body 100 and located between the support 110 and the screw post 120. The internal reinforcing rib 130 is fixedly connected to the arc-shaped sidewall 112 and the outer peripheral surface of the screw post 120.

[0029] For example, the number of internal reinforcing ribs 130 is one.

[0030] The internal reinforcing rib 130 increases the connection strength between the screw post 120 and the support portion 110, improving the overall rigidity and stability of the shrink-resistant injection molded part. The internal reinforcing rib 130 can transfer loads between the screw post 120 and the support portion 110, disperse stress, reduce local stress concentration, and lower the risk of material fatigue and fracture caused by stress concentration.

[0031] The internal reinforcing rib 130 strengthens the connection between the screw post 120 and the support 110, making the arc-shaped sidewall 112 and the screw post 120 more stable when subjected to external forces or vibrations. This effectively prevents the screw post 120 from tilting or loosening due to uneven stress during use, thus improving the product's service life and reliability.

[0032] During injection molding, the flow of plastic material directly affects the molding quality of the product. The internal reinforcing ribs 130 guide the plastic material to flow more evenly, avoiding localized plastic accumulation or poor flow. This helps reduce internal stress caused by uneven plastic flow, thereby reducing the probability of defects such as warping and deformation, and improving the dimensional accuracy and surface quality of the product.

[0033] The presence of internal reinforcing ribs 130 can adjust the local material thickness distribution to a certain extent, allowing the plastic material to shrink more evenly during cooling, reducing appearance defects caused by uneven shrinkage, and improving the overall quality of the product.

[0034] like Figure 2 and Figure 4 As shown, in one embodiment, the anti-shrinkage injection molded part further includes an external reinforcing rib 140 fixedly disposed on the outer peripheral surface of the screw post 120. The external reinforcing rib 140 connects the outer peripheral surface of the screw post 120 and the main body 100, increasing the connection strength between the screw post 120 and the main body 100, and improving the overall rigidity and stability of the anti-shrinkage injection molded part.

[0035] The external reinforcing rib 140 can transfer loads between the screw post 120 and the main body 100, disperse stress, reduce local stress concentration, and reduce the risk of material fatigue and fracture caused by stress concentration.

[0036] The presence of external reinforcing ribs 140 can guide the flow of plastic material during the injection molding process, making the material filling at the screw post 120 more uniform, reducing voids or air bubbles caused by poor material flow at the screw post 120, and further improving the appearance quality and consistency of the product.

[0037] The screw post 120 typically plays a crucial role in securing other components (such as PCBA boards), and its positional stability directly affects the product's assembly accuracy and performance. The external reinforcing rib 140 provides additional fixation and support for the screw post 120, preventing it from shifting or shaking under stress during use. This ensures that the connected components remain in the correct position, guaranteeing the product's normal function and reliability.

[0038] like Figure 4 As shown, in one embodiment, at least two external reinforcing ribs 140 are provided, and the at least two external reinforcing ribs 140 are distributed circumferentially around the screw post 120.

[0039] For example, two external reinforcing ribs 140 are provided. In another embodiment, three external reinforcing ribs 140 are provided; of course, in some other embodiments, other numbers of external reinforcing ribs 140 may be provided, such as four, five or six, etc.

[0040] At least two external reinforcing ribs 140 are distributed circumferentially around the screw post 120, which can support and reinforce the screw post 120 from multiple directions, so that the screw post 120 can obtain sufficient support force in multiple directions, greatly enhancing the overall structural stability of the connection between the screw post 120 and the main body 100, and effectively preventing the screw post 120 from tilting, shifting or loosening when subjected to external forces in different directions.

[0041] like Figure 2 and Figure 4 As shown, in one embodiment, the support portion 110 is further provided with a straight sidewall 114 connected to the arcuate sidewall 112, and a fillet 116 is provided at the connection between the straight sidewall 114 and the arcuate sidewall 112.

[0042] For example, the support portion 110 is configured as a plate structure extending in a straight line.

[0043] When the straight sidewall 114 is directly connected to the curved sidewall 112, the abrupt change in geometry will cause a large stress concentration at the connection point when subjected to external forces. However, by setting the fillet 116, the stress can be smoothly transitioned at the connection point, avoiding stress concentration at sharp corners. This greatly reduces the risk of structural cracking and damage caused by stress concentration, and improves the structural strength and reliability of the entire support 110 and even the entire injection molded part.

[0044] In addition, by setting the fillet 116, stress concentration at the connection between the straight sidewall 114 and the arc sidewall 112 is reduced, the overall rigidity and stability of the support 110 are improved, the injection molding process is optimized, voids, bubbles and defects caused by poor material flow are reduced, and the appearance quality and consistency of the product are improved.

[0045] like Figure 5 As shown, in a second aspect, embodiments of this application also provide an anti-deformation mold 300 for manufacturing anti-shrinkage injection molded parts as described in any of the above embodiments. The anti-deformation mold 300 includes a mold body, which has a first cavity 310 for forming a main body 100, a second cavity 320 for forming a support 110, and a third cavity 330 for forming a screw post 120. A first steel core 350 is provided between the second cavity 320 and the third cavity 330 to define the arcuate sidewall 112 and the outer peripheral surface of the screw post 120. The first steel core 350 is fixedly connected to the mold body and is a metal component disposed between the second cavity 320 and the third cavity 330 in the anti-deformation mold 300.

[0046] The minimum thickness of the first steel core 350 is L, where 0.75mm ≤ L ≤ 2mm. This ensures that the first steel core 350 possesses sufficient strength and rigidity to withstand the enormous pressure generated by high-pressure plastic injection and the effects of high-temperature environments during injection molding, effectively resisting deformation. This helps maintain the precise shape of the cavity, ensuring the stability and reliability of the mold during long-term use, and reducing production failures and defective products caused by mold deformation.

[0047] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A shrink-resistant injection molded part, characterized in that, include: Main body (100); A support part (110) is fixedly disposed on the main body part (100); A screw post (120) is fixedly disposed on the main body (100) near the support (110). The side wall of the support (110) near the screw post (120) is configured as an arc-shaped side wall (112) concentric with the outer peripheral surface of the screw post (120). A distance L is provided between the arc-shaped side wall (112) and the outer peripheral surface of the screw post (120), where L=Rr, the radius of the arc-shaped side wall (112) is R, the radius of the outer peripheral surface of the screw post (120) is r, and 0.75mm≤L≤2mm.

2. The anti-shrinkage injection molded part according to claim 1, characterized in that, It also includes an internal reinforcing rib (130) fixedly disposed on the main body (100) and located between the support (110) and the screw post (120), the internal reinforcing rib (130) being fixedly connected to the outer peripheral surface of the arc-shaped sidewall (112) and the screw post (120).

3. The anti-shrinkage injection molded part according to any one of claims 1 to 2, characterized in that, It also includes an external reinforcing rib (140) fixedly disposed on the outer peripheral surface of the screw post (120), the external reinforcing rib (140) connecting the outer peripheral surface of the screw post (120) and the main body (100).

4. The anti-shrinkage injection molded part according to claim 3, characterized in that, At least two external reinforcing ribs (140) are provided, and at least two external reinforcing ribs (140) are distributed circumferentially around the screw post (120).

5. The anti-shrinkage injection molded part according to claim 1, characterized in that, The support part (110) is also provided with a straight sidewall (114) connected to the arc-shaped sidewall (112), and the connection between the straight sidewall (114) and the arc-shaped sidewall (112) is provided with a rounded corner (116).

6. An anti-deformation mold, characterized in that, For manufacturing the anti-shrinkage injection molded part as described in any one of claims 1 to 5, the anti-deformation mold (300) includes a mold body having a first cavity (310) for forming the main body (100), a second cavity (320) for forming the support (110) and a third cavity (330) for forming the screw post (120), wherein a first steel core (350) for defining the arcuate sidewall (112) and the outer peripheral surface of the screw post (120) is provided between the second cavity (320) and the third cavity (330), and the minimum thickness of the first steel core (350) is L.

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