Injection mold gate structure for preventing contaminants from entering a mold cavity

Abstract

The application discloses an injection mold gate structure capable of preventing impurities from entering a mold cavity, comprising a cold material well main body in a hollow cavity, a triangular glue port thimble top end extending to the bottom of the cold material well main body and closely adhering to the bottom, arc-shaped corner surfaces being arranged between two adjacent side edges of the triangular glue port thimble, the arc-shaped corner surfaces being connected with the inner wall of the cold material well main body, the triangular glue port thimble adopting a right triangular columnar structure, completely covering the cold material well bottom without a ejection dead angle, cooperating with the arc-shaped corner surfaces to break the edge, completely cleaning the material cutting impurities, compared with a circular or square thimble, the triangular glue port thimble has a larger contact area and stronger friction force, effectively avoiding slipping, the surface is high-precision polished and a reasonable gap is reserved, cooperating with the cold material well inner wall polishing and the round corner, no additional material cutting is generated, the arc-shaped corner surfaces prevent scratching, the structure is simple, no large-scale modification is needed, the triangular glue port thimble is suitable for various molds, improves the product qualified rate, and reduces the material and labor costs.

Description

Technical Field

[0001] This invention relates to a gate structure for injection molds that prevents impurities from entering the mold cavity, and particularly to a gate structure for injection molds that prevents impurities from entering the mold cavity. Background Technology

[0002] In injection molding, the cold slug well is a key component of the injection mold gating system. It is typically located at the end of the main runner and the junction of the branch runners. Its core function is to collect the low-temperature cold slug (usually more than 20°C below the material's glass transition temperature) formed during melt flow, preventing it from entering the mold cavity and causing surface defects such as flow lines and silver streaks. It also buffers pressure fluctuations during the initial injection phase. Cold slug wells can also be placed near the gate and at the end of the melt flow to further collect the cooling leading edge slug, preventing it from affecting product quality. However, existing cold slug well designs only focus on trapping cold slug, neglecting the handling of shavings and impurities generated during injection (such as debris generated by friction between the molten material and the runner wall, and impurities mixed in with the raw material).

[0003] In the prior art, cold material wells are mostly simple hollow cavity structures, which only achieve cold material retention through volume design. This is the prior art solution that is closest to the present invention. The existing technical solution has the following drawbacks: First, it cannot intercept shavings and impurities. When the molten material carries shavings and impurities into the cold slug well, the impurities will enter the mold cavity along with the molten material, causing defects such as surface scratches and impurity inclusions in the injection molded products. In severe cases, it can also reduce the structural strength of the products, especially for high-precision products such as high-gloss and transparent parts, where the impact is more significant and may even lead to product scrapping and increased production costs. Second, it is easy for impurities to accumulate. The rough inner wall of some cold slug wells can easily lead to the accumulation of shavings and impurities. After long-term use, the accumulated impurities will fall off and enter the mold cavity, further affecting the product quality. Third, it can easily aggravate the generation of shavings. The unreasonable design of the connection between the cold slug well and the main runner can easily generate shearing forces, aggravating the generation of shavings and further exacerbating the problem of impurities entering the mold cavity. Fourth, there is a risk of gas carrying impurities. The existing cold slug wells do not have a reasonable venting structure, and the internal gas cannot be discharged in time, easily carrying shavings and impurities into the mold cavity, further affecting the product quality.

[0004] The core reason for the above-mentioned shortcomings of the existing technology is that the existing cold slug well is designed only around the single function of "cold slug interception" and does not have a dedicated impurity interception mechanism. At the same time, the structural design does not take into account the need to reduce the generation of slugs, avoid the accumulation of impurities and exhaust internal gas, which makes it impossible to meet the dual needs of cold slug interception and impurity control, and cannot solve the technical problem of slugs and impurities being injected into the mold cavity. Summary of the Invention

[0005] This invention provides an injection mold gate structure to prevent impurities from entering the mold cavity, overcoming the shortcomings of existing cold slug well structures that are simple and lack impurity interception and venting functions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention discloses an injection mold gate structure to prevent impurities from entering the mold cavity, including a cold slug well body with a hollow cavity, a triangular ejector pin extending to the bottom of the cold slug well body and closely fitting the bottom; an arc-shaped corner surface is provided between the adjacent two sides of the triangular ejector pin, and the arc-shaped corner surface is in contact with the inner wall of the cold slug well body.

[0007] Furthermore, the top of the cold slug well body is provided with a feed inlet communicating with the main channel, and the lower part of its side wall is provided with a discharge outlet communicating with the mold cavity feed channel, and the bottom surface of the discharge outlet is higher than the bottom of the cold slug well body.

[0008] Furthermore, the triangular ejector pin is an equilateral triangle or an isosceles triangle, and its bottom is fixedly connected to the mold ejection mechanism. The cold sluice gate above the discharge port has an exhaust groove on its main side wall.

[0009] Furthermore, the side length of the triangular ejector pin is matched with the inner diameter of the bottom of the cold slug well body, and both are made of high-temperature resistant mold steel.

[0010] Furthermore, the bottom of the cold material well body is provided with a rounded corner structure.

[0011] Furthermore, a gap is left between the triangular rubber nozzle pin and the inner wall of the cold material well body.

[0012] Furthermore, the cavity volume of the main body of the cold material well is 1.2 to 1.5 times the volume of the main channel's large end, and the ratio of the depth of the main body of the cold material well to the diameter of the main channel's large end is 0.8 to 1.2.

[0013] The beneficial effects achieved by this invention are: 1. Completely solves the problem of residual shavings. The triangular ejector pin adopts an equilateral triangular columnar structure. The three sides can fully cover the bottom of the cold slug well, with no dead corners for ejection. Combined with the edge-breaking effect of the arc-shaped corner surface, it can thoroughly clean the shavings and impurities attached to the bottom and inner wall of the cold slug well, preventing shavings and impurities from entering the mold cavity from the source, and avoiding defects such as scratches and inclusions in the parts.

[0014] 2. Strong ejection stability: Compared with existing round and square ejector pins, the triangular structure has a larger contact area with cold material and material scrap, resulting in stronger friction during ejection. This effectively prevents slippage and ensures that cold material and material scrap impurities are completely removed with each ejection, preventing residue buildup.

[0015] 3. No additional material chipping is generated. The surface of the triangular ejector pin is polished with high precision and a reasonable gap is reserved with the inner wall of the cold slug well. Combined with the polishing and rounded corner structure of the inner wall of the cold slug well, friction is avoided to generate new material chipping, further improving the anti-material chipping effect. At the same time, its arc-shaped corner surface can prevent the sharp end from scratching the inner wall of the cold slug well, reducing the possibility of material chipping caused by wear on the inner wall.

[0016] 4. Simple structure and strong practicality. By optimizing the shape of the ejector pin to a triangle, there is no need to make major modifications to the main body of the cold slug well. It is compatible with various injection molds, with low modification costs and convenient installation. At the same time, it also has the function of cold slug interception. While preventing material chipping and injection, it avoids product defects caused by cold slug, greatly improves the product qualification rate, and reduces raw material loss and manual cleaning costs. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the exhaust groove structure of the present invention; Figure 3 This is a schematic diagram of the glue outlet body and the discharge port of the present invention.

[0018] In the diagram: 1. Cold material well body; 2. Inlet; 3. Outlet; 4. Triangular ejector pin; 5. Venting groove. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] Example 1

[0021] like Figure 1-3 As shown, an injection mold gate structure for preventing impurities from entering the mold cavity includes a cold slug well body 1 and a triangular ejector pin 4. The cold slug well body 1 is mounted at the end of the main runner of the injection mold and precisely connected to the main runner. The cold slug well body 1 is a hollow cavity structure made of high-temperature mold steel (such as Cr12MoV) and serves as a collection carrier for cold material and shavings impurities. A feed port 2 is opened at the top of the cold slug well body 1 and is fixedly connected to the bottom of the main runner. The diameter of the feed port 2 is the same as the diameter of the large end of the main runner to ensure smooth flow of molten material. A discharge port 3 is opened at the lower part of the side wall of the cold slug well body 1 and is correspondingly connected to the mold cavity feed channel. The height of the discharge port 3 is higher than the bottom of the cold slug well body 1 and is used to transport clean molten material to prevent cold material and residual impurities from entering the mold cavity.

[0022] The triangular ejector pin 4 is a key component to prevent shavings and impurities from entering the mold cavity. It has an overall triangular columnar structure, preferably an equilateral or isosceles triangle, adapted to the shape of the bottom of the cold slug well body 1. The bottom of the triangular ejector pin 4 is fixedly connected to the mold ejection mechanism, and the top extends to the bottom of the cold slug well body 1, fitting tightly against it to prevent friction from generating new shavings. Its three sides can completely cover the bottom of the cold slug well body 1, eliminating any ejection dead corners. An arc-shaped corner surface is provided between adjacent sides of the triangular ejector pin 4. This corner surface contacts the inner wall of the cold slug well body 1, allowing the cold material and attached shavings to experience slight edge breakage during ejection, facilitating complete detachment from the inner wall of the cold slug well body 1 and preventing residue.

[0023] The side length of the triangular ejector pin 4 is adapted to the inner diameter of the bottom of the cold slug well body 1. It is made of the same high-temperature resistant mold steel as the cold slug well body 1, with a polished surface (surface roughness Ra≤0.8μm). A reasonable gap is reserved between the ejector pin and the inner wall of the cold slug well body 1, controlled within the range of 0.015mm~0.025mm. This gap size can accommodate molten materials of different viscosities, preventing molten material from entering the gap and generating shavings, while ensuring smooth and uninterrupted ejection. This reduces adhesion to cold material and shavings, and also prevents shavings from being generated by its own friction. The triangular structure increases the contact area with cold material and shavings, improving friction during ejection, preventing slippage, and ensuring that cold material and attached shavings are completely ejected. The inner wall of the cold slug well body 1 is also polished, with rounded corners at the bottom (rounded radius 1-3mm), which, together with the triangular ejector pin 4, further prevents shavings from accumulating in the corners.

[0024] To further enhance the anti-chipping effect, an exhaust groove 5 is provided on the side wall of the cold slug well body 1 above the outlet 3. The groove is 0.02-0.03mm deep and 2-3mm wide, and is used to discharge the gas inside the cold slug well body 1 to the outside of the mold, preventing the gas from carrying chipping impurities into the mold cavity. The volume of the cold slug well body 1 is 1.2-1.5 times the volume of the large end of the main channel, and the ratio of its depth to the diameter of the large end of the main channel is 0.8-1.2, ensuring that the cold material is fully intercepted and preventing the cold material from carrying chipping impurities into the mold cavity.

[0025] The working process and anti-chipping principle of this invention are as follows: Molten material flows from the main channel into the inlet 2 → enters the cold slug well body 1 → cold material settles at the bottom, and chipping impurities adhere to the surface of the cold material and the bottom of the cold slug well body 1 → clean molten material flows into the mold cavity through the outlet 3, and internal gas is discharged through the venting groove 5; the mold is equipped with an independent ejection system, including a conventional ejector pin for ejecting the product and a triangular ejector pin 4 for ejecting the cold material. After injection molding, when the ejection system is activated, the triangular ejector pin 4 moves synchronously or sequentially with the product ejector pin: first, the triangular ejector pin 4 ejects the cold material and impurities out of the cold slug well body 1, while the product ejector pin ejects the product away from the core. The two have different strokes, ensuring that the product and cold material are separated and do not interfere with each other. The operator then removes the product and waste material respectively. Subsequently, the triangular ejector pin 4 resets, waiting for the next injection molding cycle. Since the waste material has been completely removed, the interior of the cold slug well body 1 remains clean, preventing chipping impurities from entering the mold cavity at the source.

[0026] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The terminology used in the description of this application is only for describing specific embodiments and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings indicate similar items, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0027] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0028] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

Claims

1. A gate structure for an injection mold that prevents impurities from entering the mold cavity, characterized in that, The cold material well body includes a hollow cavity, and the top of the triangular glue nozzle pin extends to the bottom of the cold material well body and fits tightly against the bottom. An arc-shaped corner surface is provided between the adjacent two sides of the triangular glue nozzle pin, and the arc-shaped corner surface is in contact with the inner wall of the cold material well body.

2. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 1, characterized in that, The top of the cold slug well body is provided with a feed inlet that communicates with the main channel, and the lower part of its side wall is provided with a discharge outlet that communicates with the mold cavity feed channel, and the bottom surface of the discharge outlet is higher than the bottom of the cold slug well body.

3. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 1, characterized in that, The triangular ejector pin is an equilateral triangle or an isosceles triangle, and its bottom is fixedly connected to the mold ejection mechanism. An exhaust groove is provided on the side wall of the cold sluice gate above the discharge port.

4. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 1, characterized in that, The side length of the triangular ejector pin is matched with the inner diameter of the bottom of the cold slug well body, and both are made of high-temperature resistant mold steel.

5. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 1, characterized in that, The bottom of the cold material well body is provided with a rounded corner structure.

6. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 1, characterized in that, A gap is left between the triangular rubber nozzle pin and the inner wall of the cold material well body.

7. The injection mold gate structure for preventing impurities from entering the mold cavity according to claim 2, characterized in that, The cavity volume of the main body of the cold material well is 1.2 to 1.5 times the volume of the main channel's large end, and the ratio of the depth of the main body of the cold material well to the diameter of the main channel's large end is 0.8 to 1.2.

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