Automatic ejection mechanism for injection moulds

Abstract

This utility model relates to injection mold demolding technology and discloses an automatic ejection mechanism for injection molds, including a base and a mold head assembly. The mold head assembly includes a moving mold plate and a fixed mold, with a receiving hole in the middle of the fixed mold. An ejection assembly is mounted on the base, comprising an ejector pin, a first ejection structure, and a second ejection structure. The ejector pin engages with the receiving hole and can move axially. The first and second ejection structures are connected to the base via a slide rail. The first ejection structure separates the plastic part from the fixed mold; the second ejection structure ejects the plastic part from the fixed mold. This two-stage ejection method, involving a release followed by a push, reduces the initial stress peak during ejection, preventing whitening, cracking, or deformation of the molded part. It is particularly suitable for non-destructive demolding of high-surface-quality and deep-cavity, thin-walled plastic parts.

Description

Technical Field

[0001] This utility model relates to injection mold demolding technology, and more particularly to an automatic ejection mechanism for injection molds. Background Technology

[0002] In the field of injection molding, demolding is crucial. For plastic products with deep cavities, complex structures, or high surface finish requirements, after cooling and solidification, extremely strong vacuum adsorption and physical clamping forces can easily form between the product and the mold cavity surface.

[0003] In existing technologies, a single-stroke, large-stroke ejection method is commonly used, where a large force is applied by an ejector pin or plate to eject the product instantaneously. This method has significant drawbacks: at the initial moment of ejection, a huge vacuum suction force and static friction must be overcome in one go, resulting in excessive ejection impact force. For thin-walled, deep-cavity, or brittle plastic products, the instantaneous impact can easily cause localized stress concentration, leading to defects such as whitening, cracking, and permanent deformation. This severely affects the product's appearance quality and dimensional accuracy, reducing the production yield.

[0004] Although some molds have attempted to improve the situation by increasing the number of ejector pins or optimizing the ejector pin layout, they have failed to fundamentally solve the problem of "excessive initial ejection force".

[0005] Therefore, it is necessary to design a mechanism that can achieve smooth, phased ejection, thereby breaking the vacuum seal at the initial stage of ejection and converting the huge adsorption force into a smaller sliding friction force, thus achieving non-destructive ejection of precision products. Utility Model Content

[0006] In order to overcome the shortcomings of the existing technology, this utility model proposes an automatic ejection mechanism for injection molds.

[0007] The technical solution of this utility model is implemented as follows:

[0008] An automatic ejection mechanism for an injection mold includes a base and a mold head assembly. The mold head assembly includes a moving mold plate and a fixed mold, the fixed mold having a receiving hole in the middle.

[0009] Its features are,

[0010] The base is provided with an ejector assembly, which includes an ejector pin, a first ejector structure, and a second ejector structure. The ejector pin engages with a receiving hole and can move along its axial direction. The first and second ejector structures are connected to the base via slide rails.

[0011] The first ejection structure separates the plastic part from the fixed mold; the second ejection structure ejects the plastic part from the fixed mold.

[0012] Preferably, the first ejection structure includes a first push cylinder and a first push plate, the first push plate being connected to the ejector pin, and the first push cylinder being used to drive the ejector pin to move axially along the receiving hole to completely eject the plastic part from the mold.

[0013] Preferably, the second ejection structure includes a second push cylinder, a second push plate, a spring seat, a limiting plate, a threaded sleeve, a shift fork, and an adjusting cylinder.

[0014] The second push plate is connected to the ejector pin and a spring seat is provided between them. The threaded sleeve is threadedly engaged with the ejector pin. The shift fork is fixedly connected to the threaded sleeve. The adjusting cylinder is connected to the shift fork and is used to control the rotation of the shift fork to drive the threaded sleeve to rotate, so that the ejector pin produces a small displacement.

[0015] Preferably, the second ejector structure drives the ejector pin to generate a small displacement of .-mm, which is used to break the vacuum seal between the plastic part and the fixed mold.

[0016] Preferably, the output shaft of the adjusting cylinder is connected to one end of the shift fork. The adjusting cylinder drives the shift fork to rotate, thereby driving the threaded sleeve to rotate, causing the ejector pin to move axially along the receiving hole.

[0017] Preferably, the second ejection structure further includes a motion amplitude, and the bottom of the adjusting cylinder is provided with a motion amplitude.

[0018] Preferably, the outer side of the fixed mold is provided with an injection hole, through which the molten injection material enters the interior of the fixed mold.

[0019] The automatic ejection mechanism of the injection mold according to this utility model has the following beneficial effects:

[0020] 1. The second ejection structure first drives the ejector pin to generate a small displacement. This displacement is sufficient to break the vacuum seal between the part and the mold cavity, but not enough to completely detach the part. This transforms the insurmountable vacuum suction force into a smaller sliding friction force, creating extremely favorable conditions for subsequent full ejection. Subsequently, the first ejection structure performs the full-stroke ejection action. This reduces the initial peak stress during the ejection process, effectively preventing defects such as whitening, cracking, and deformation in the part. It is particularly suitable for high-quality production of precision, easily deformable plastic parts.

[0021] 2. The entire ejection process, from micro-motion release to full ejection, is controlled sequentially by the adjusting cylinder, the second pushing cylinder, and the first pushing cylinder, requiring no manual intervention. This ensures consistency, reliability, and repeatability of the actions, and also achieves efficient synchronization with the injection molding machine cycle, facilitating automated continuous production and improving overall production efficiency.

[0022] 3. Through the helical transmission between the threaded sleeve and the ejector pin, and with the adjustment cylinder driving the shift fork and the threaded sleeve to rotate, precise control of the ejector pin's minute displacement is achieved. This structure is compact and can be integrated into a standard mold base without occupying too much space. Furthermore, by adjusting the rotation angle of the threaded sleeve, the pre-ejection displacement can be flexibly set to adapt to the demolding requirements of products with different materials and structures, demonstrating strong versatility. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the automatic ejection mechanism of this utility model;

[0024] Figure 2 This is a schematic diagram of the automatic ejection mechanism of this utility model from another angle;

[0025] Figure 3 This is a partial structural schematic diagram of the automatic ejection mechanism of this utility model;

[0026] Figure 4 This is another angular structural diagram of the automatic ejection mechanism of this utility model;

[0027] Figure 5 This is a partial structural diagram of the automatic ejection mechanism of this utility model.

[0028] The reference numerals in the attached drawings are as follows: base 10, mold head assembly 20, ejection assembly 30, ejector pin 31, first ejection structure 32, second ejection structure 33, moving mold plate 201, fixed mold 202, receiving hole 203, injection hole 204, first push cylinder 321, first push plate 322, second push cylinder 331, second push plate 332, spring seat 34, slide rail 35, limit plate 333, threaded sleeve 334, shift fork 335, and adjusting cylinder 336. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0030] like Figures 1 to 5 As shown, the automatic ejection mechanism of this injection mold includes a base 10 and a mold head assembly 20, wherein the mold head assembly 20 is connected to other external components and its opening and closing are controlled.

[0031] The base 10 is provided with an ejector assembly 30, which includes an ejector pin 31, a first ejector structure 32 and a second ejector structure 33.

[0032] The mold head assembly 20 includes a movable template 201, one end of which is fixedly connected to a fixed mold 202. The fixed mold 202 has a receiving hole 203 in the middle, and the ejector pin 31 cooperates with the receiving hole 203 and can move axially along the receiving hole 203.

[0033] An injection hole 204 is provided on the outer side of the fixed mold 202, through which the molten injection material enters the interior of the fixed mold 202. The fixed mold 202 cooperates with another fixed mold 202 to form a sealed chamber.

[0034] The first ejection structure 32 and the second ejection structure 33 are connected to the base 10 via a slide rail 35. The first ejection structure 32 includes a first push cylinder 321, and the output shaft of the first push cylinder 321 is fixedly connected to a first push plate 322.

[0035] The first push plate 322 is connected to the ejector pin 31. The first push cylinder 321 can drive the ejector pin 31 to move axially along the receiving hole 203 via the first push plate 322, and eject the material injected into the fixed mold 202.

[0036] In this embodiment, the second ejection structure 33 includes a second push cylinder 331, and a second push plate 332 is connected to the output shaft of the second push cylinder 331. The second push plate 332 is connected to the ejector pin 31, and a spring seat 34 is provided between the second push plate 332 and the ejector pin 31.

[0037] The second ejector structure 33 further includes a limiting plate 333 and a threaded sleeve 334. The threaded sleeve 334 is threadedly engaged with the ejector pin 31. When the threaded sleeve 334 is rotated, the ejector pin 31 will move axially along the receiving hole 203.

[0038] In this embodiment, a shift fork 335 is fixedly connected to one end of the threaded sleeve 334, and an adjusting cylinder 336 is provided on one side of the shift fork 335. The output shaft of the adjusting cylinder 336 is connected to one end of the shift fork 335. The adjusting cylinder 336 is located on one side of the base 10, and a movement amplitude 337 is provided at the bottom of the adjusting cylinder 336.

[0039] Specifically, after cooling, deep-cavity plastic products with high surface finish form a strong vacuum adsorption force between the mold 202 and the plastic part. If a large force is used to eject them at once, the resistance that needs to be overcome in the initial instant is extremely large, which can easily lead to deformation, whitening, or cracking of thin-walled products due to excessive impact force or stress concentration.

[0040] In this embodiment, when ejection is required, the second ejection structure 33 is first controlled to drive the ejector pin 31 to produce a small displacement, typically 0.5-2mm. This small displacement maintains a vacuum seal between the plastic and the fixed mold 202, converting the adsorption force into a smaller frictional force, facilitating subsequent complete ejection.

[0041] like Figure 2 As shown, the specific working principle is as follows: the output end of the adjusting cylinder 336 is extended, and the adjusting cylinder 336 drives the shift fork 335 along... Figure 2 Rotate in the direction of the middle arrow. At this time, the shift fork 335 drives the threaded sleeve 334 to rotate. The threaded sleeve 334 engages with the ejector pin 31 and causes a slight displacement, allowing the plastic part to separate from the surface of the fixed mold 202.

[0042] Subsequently, in the second ejection structure 33, the first pushing cylinder 321 is controlled, and the first pushing plate 322 drives the ejector pin 31 to move axially along the receiving hole 203, completely ejecting the plastic part. This reduces the internal stress and deformation risk of plastic products, effectively protecting their appearance and quality, and is particularly suitable for precision and easily deformable plastic parts.

[0043] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An automatic ejection mechanism for an injection mold, comprising a base (10) and a mold head assembly (20), the mold head assembly (20) comprising a moving mold plate (201) and a fixed mold (202), the fixed mold (202) having a receiving hole (203) in the middle. Its features are, The base (10) is provided with an ejector assembly (30), which includes an ejector pin (31), a first ejector structure (32), and a second ejector structure (33). The ejector pin (31) engages with the receiving hole (203) and can move along its axial direction. The first ejector structure (32) and the second ejector structure (33) are connected to the base (10) via a slide rail (35). The first ejection structure (32) separates the plastic part from the fixed mold (202); the second ejection structure (33) ejects the plastic part from the fixed mold (202).

2. An automatic ejection mechanism for an injection mold according to claim 1, wherein The first ejection structure (32) includes a first push cylinder (321) and a first push plate (322). The first push plate (322) is connected to the ejector pin (31). The first push cylinder (321) is used to drive the ejector pin (31) to move axially along the receiving hole (203) to completely eject the plastic part in the fixed mold (202).

3. An automatic ejection mechanism for an injection mold according to claim 1, wherein The second ejection structure (33) includes a second push cylinder (331), a second push plate (332), a spring seat (34), a limit plate (333), a threaded sleeve (334), a shift fork (335), and an adjusting cylinder (336). The second push plate (332) is connected to the ejector pin (31) and a spring seat (34) is provided between them. The threaded sleeve (334) is threadedly engaged with the ejector pin (31). The shift fork (335) is fixedly connected to the threaded sleeve (334). The adjusting cylinder (336) is connected to the shift fork (335) and is used to control the rotation of the shift fork (335) to drive the threaded sleeve (334) to rotate, so that the ejector pin (31) produces a small displacement.

4. An automatic ejection mechanism for an injection mold according to claim 3, wherein The second ejection structure (33) drives the ejector pin (31) to generate a small displacement of 0.5-2mm, which is used to break the vacuum seal between the plastic part and the fixed mold (202).

5. An automatic ejection mechanism for an injection mold according to claim 3, wherein The output shaft of the regulating cylinder (336) is connected to one end of the shift fork (335). The regulating cylinder (336) drives the shift fork (335) to rotate, thereby driving the threaded sleeve (334) to rotate, so that the ejector pin (31) moves axially along the receiving hole (203).

6. An automatic ejection mechanism for an injection mold according to claim 3, wherein The second ejection structure (33) also includes a motion amplitude (337), and the bottom of the adjusting cylinder (336) is provided with a motion amplitude (337).

7. An automatic ejection mechanism for injection molds according to claim 1, characterized in that, The fixed mold (202) is provided with an injection hole (204) on the outside, and the molten injection material enters the fixed mold (202) through the injection hole (204).

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