Undercut structure for forced demolding, injection mold and injection method

Abstract

The present invention provides an undercut structure, an injection mold and an injection molding method for forced demolding, including an undercut cavity and an opening of the undercut structure. The undercut cavity is communicated with the opening of the undercut structure, and a concave is formed on the side wall of the undercut cavity adjacent to the opening of the undercut structure; an R corner is connected between the opening of the undercut structure and the outer wall of the undercut cavity, and the clockwise included angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure is at least 45°. By setting the clockwise included angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure to be at least 45°, when ejecting, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the concave of the undercut cavity, so as to synchronously and naturally form a space allowing the deformation of the product, thereby completing forced demolding with little or no change in appearance, and the mold structure is simple, the cost is low, and the production is reliable and practical.

Description

Technical Field

[0001] The present invention relates to the technical field of injection molds, and in particular to an undercut structure for forced demoulding, an injection mold and an injection molding method. Background Art

[0002] In plastic molds, materials such as ABS or PC are used. With the development of technology, the structural design of injection molded products has become increasingly complex. If the mold release direction is undercut, demoulding will be difficult and the maintenance risk during production will be high.

[0003] Currently, for products with undercuts in the ejection direction, secondary ejection can be used to leave room for deformation, allowing the product to be ejected and removed, but this method is complex. Alternatively, the slide can be opened to leave room for deformation, allowing the product to be ejected and removed, but this takes up too much mold space, reduces the number of ejection cavities, and increases production costs.

[0004] The existing Chinese patent application document with publication number CN106378912A discloses an injection mold with a forced demolding structure, including: the first mold opening is between the support plate and the movable template, and the movable core gradually separates from the product plastic part, thereby providing space for the second undercut to elastically deform inward during forced demolding; further, the push plate and the fixed template are separated toward each other, the space between the push plate and the fixed template is opened, and the slider performs lateral core pulling on the product plastic part; after the lateral core pulling is completed, by pushing the pusher bottom plate, the pusher plate is pushed away from the movable template to move toward each other, at this time, the space between the push plate and the movable template is opened, the movable mold core is separated from the product plastic part, and the movable core is separated from the product plastic part, thereby providing space for elastic deformation inward during forced demolding of the first undercut; at the same time, the movable mold insert on the push plate pushes out the product plastic part as the push plate moves, so that the forced demolding of the product plastic part is completed.

[0005] The forced demoulding structure in the existing technology leaves space for inward elastic deformation, and then the product is ejected and forcibly removed, which makes it difficult to open the mold. In addition, the inner side of some products has functional parts and cannot leave space for inward elastic deformation. There is room for improvement. Summary of the Invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide an undercut structure, an injection mold and an injection molding method for forced demoulding.

[0007] According to the present invention, an undercut structure for forced demolding includes an undercut cavity and an opening of the undercut structure. The undercut cavity is connected to the opening of the undercut structure, and an indentation is formed on the side wall adjacent to the opening of the undercut structure. An R angle is formed between the opening of the undercut structure and the outer wall of the undercut cavity, and the clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure is at least 45°.

[0008] Preferably, the maximum thickness difference between the concave and the opening of the reverse buckle structure is 0.1-0.2 mm.

[0009] Preferably, the clockwise angle between the central axis of the reverse buckle cavity and the inner concave side wall is less than or equal to the clockwise angle between the central axis of the reverse buckle cavity and the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure.

[0010] Preferably, the size of the R angle is as large as possible on the premise of satisfying the inner concave amount and the clockwise angle between the central axis of the reverse buckle cavity and the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure.

[0011] Preferably, when ejecting, the size of the deformation space formed at the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure is larger than the reverse buckle amount at the inner concave part of the reverse buckle cavity.

[0012] Preferably, the reverse buckle structure includes an inner reverse buckle or an outer reverse buckle.

[0013] An injection mold for forced demolding provided by the present invention further includes a gate and an injection runner, and the injection runner communicates with the gate and the opening of the reverse buckle structure.

[0014] An injection method for forced demolding provided by the present invention includes the following steps:

[0015] S1. After the mold is closed, injection molding is carried out to fill the material level completely.

[0016] S2. After pressure holding and cooling, an ejection action is carried out to complete demolding.

[0017] Preferably, the injection molding material includes ABS or POM.

[0018] Preferably, for S2, when the ejection action is carried out, the size of the deformation space formed at the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure is larger than the reverse buckle amount at the inner concave part of the reverse buckle cavity.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. By setting the clockwise angle between the central axis of the reverse buckle cavity and the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure to be at least 45°, when ejecting, the size of the deformation space formed at the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure is larger than the reverse buckle amount at the inner concave part of the reverse buckle cavity, so that a space allowing the product to deform is naturally formed synchronously, so that forced demolding can be completed with little or no change in appearance, and the mold structure is simple, the cost is low, and the production is reliable and practical.

[0021] 2. The R angle connected between the opening of the reverse buckle structure and the outer wall of the reverse buckle cavity in the present invention can reduce the scratch during forced demolding deformation, which helps to improve the quality of the injection molded product.

[0022] 3. By setting the clockwise angle between the central axis of the reverse buckle cavity and the inner concave side wall to be less than or equal to the clockwise angle between the central axis of the reverse buckle cavity and the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure in the present invention, it helps to improve the convenience of demolding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 It is a schematic diagram mainly showing the internal reverse buckle type reverse buckle structure of the present invention;

[0025] Figure 2 It is a schematic diagram mainly showing the external reverse buckle type reverse buckle structure of the present invention;

[0026] Figure 3 It is a schematic diagram mainly showing the ejection structure when the product is ejected by 0.1 mm of the present invention;

[0027] Figure 4 It is a schematic diagram mainly showing the ejection structure when the product is ejected by 0.4 mm of the present invention.

[0028] As shown in the figure: 1. Inner concavity; 2. R angle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0030] As Figure 1 and Figure 2 shown, a reverse buckle structure for forced demolding provided by the present invention includes a reverse buckle cavity and an opening of the reverse buckle structure. The reverse buckle cavity is communicated with the opening of the reverse buckle structure, and an inner concavity 1 is formed on the side wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure. An R angle 2 is connected between the opening of the reverse buckle structure and the outer wall of the reverse buckle cavity, and the clockwise angle between the central axis of the reverse buckle cavity and the outer wall of the reverse buckle cavity adjacent to the opening of the reverse buckle structure is at least 45°.

[0031] Set the clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure as C, and the clockwise angle between the central axis of the undercut cavity and the inner concave 1 side wall as B. The angle of B is less than or equal to the angle of C. And the larger the angle of C, the more beneficial it is for demolding.

[0032] Specifically, the maximum thickness difference between the inner concave 1 and the opening of the undercut structure is 0.1 - 0.2 mm. The size of the R angle 2 is as large as possible on the premise of meeting the inner concave 1 amount and the clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening. Thus, it can avoid scratching during forced demolding deformation.

[0033] During ejection, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the inner concave 1 of the undercut cavity. Thus, a space that can allow the product to deform can be naturally formed synchronously, solving the problem of undercut demolding.

[0034] Furthermore, the undercut structure includes an internal undercut or an external undercut. The demolding principles of the internal undercut and the external undercut are the same. The following will take the internal undercut structure as an example for elaboration. The internal undercut of the present application preferably adopts an internal undercut with a "C" - type structure.

[0035] The present invention also provides an injection mold for forced demolding, which includes the above - mentioned undercut structure for forced demolding, and also includes a gate and an injection runner. The injection runner communicates with the gate and the opening of the undercut structure. After the front mold and the rear mold are closed, injection filling can be carried out through the gate and the injection runner.

[0036] The present invention also provides an injection molding method for forced demolding, which adopts the above - mentioned undercut structure for forced demolding and the injection mold for forced demolding. The injection molding method includes the following steps:

[0037] S1. After closing the mold, carry out injection filling to fully fill the material level;

[0038] S2. After pressure - holding and cooling, carry out an ejection action to complete demolding. For S2, when carrying out the ejection action, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the inner concave 1 of the undercut cavity.

[0039] The injection material includes ABS or POM.

[0040] As Figure 3 shown, during the ejection process, the product is ejected by 0.1 mm, the undercut amount at the inner concave 1 of the undercut structure is 0.05 mm, and the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is 0.06 mm. Thus, the product has sufficient deformation space during the forced ejection process.

[0041] As Figure 4As shown, continue to eject. The product is ejected by 0.4 mm. The undercut amount at the concave part 1 of the undercut structure is 0.13 mm. The size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is 0.23 mm. Thus, during the forced ejection process of the product, there is sufficient deformation space. Therefore, forced demolding can be completed with little or no change in appearance, making the mold structure simple, with low cost and reliable and practical production.

[0042] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application 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 thus should not be construed as a limitation to the present application.

[0043] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An undercut structure for a forced demolding injection mold, characterized in that It includes an undercut cavity and an opening of the undercut structure. The undercut cavity is in communication with the opening of the undercut structure, and a concave portion (1) is formed on the side wall of the undercut cavity adjacent to the opening of the undercut structure; An R corner (2) is connected between the opening of the undercut structure and the outer wall of the undercut cavity. The clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure is at least 45°; The undercut cavity is an integral structure.

2. The undercut structure for a forced demolding injection mold according to claim 1, wherein The maximum thickness difference between the concave portion (1) and the opening of the undercut structure is 0.1 - 0.2 mm; During ejection, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the concave portion of the undercut cavity.

3. The undercut structure for a forced demolding injection mold according to claim 1, characterized in that, The clockwise angle between the central axis of the undercut cavity and the side wall of the concave portion (1) is less than or equal to the clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure.

4. The undercut structure for a forced demolding injection mold according to claim 1, characterized in that, The size of the R corner (2) is as large as possible on the premise of satisfying the amount of the concave portion (1) and the clockwise angle between the central axis of the undercut cavity and the outer wall of the undercut cavity adjacent to the opening of the undercut structure.

5. The undercut structure for a forced demolding injection mold as claimed in claim 1, characterized in that, During ejection, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the concave portion (1) of the undercut cavity.

6. The undercut structure for a forced demolding injection mold according to claim 1, characterized in that, The undercut structure includes an internal undercut or an external undercut.

7. An injection mold for forced demolding, characterized in that, It includes the undercut structure for a forced demolding injection mold according to any one of claims 1 - 6, and also includes a gate and an injection runner. The injection runner communicates the gate and the opening of the undercut structure.

8. An injection molding method for forced demolding, characterized in that, Using the undercut structure for a forced demolding injection mold according to any one of claims 1 - 6, the injection method includes the following steps: S1. After closing the mold, perform injection filling to fully fill the material level; S2. After pressure holding and cooling, perform an ejection action to complete demolding.

9. The injection molding method for forced demolding according to claim 8, characterized in that, The injection material includes ABS or POM.

10. The injection molding method for forced demolding according to claim 8, characterized in that, Regarding S2, when performing the ejection action, the size of the deformation space formed at the outer wall of the undercut cavity adjacent to the opening of the undercut structure is larger than the undercut amount at the concave portion (1) of the undercut cavity.

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