Nozzle structure for injection molding

Abstract

The utility model provides a nozzle structure for injection molding, which can prevent an injection molding product from generating sink marks at a sprue. The nozzle structure for injection molding includes: a resin supply channel leading to an injection space; the valve needle is arranged in the resin supply channel and is used for blocking the resin supply channel, the valve needle comprises an outer cylinder and a pin, the inner part of the outer cylinder is provided with a hollow structure, and the pin is used for moving along the inner surface of the outer cylinder in the hollow structure; the outer cylinder is used for moving to a first position adjacent to the injection molding space so as to block the resin supply channel, and the pin is positioned at a second position farther from the injection molding space than the first position so as to leave residual resin in the outer cylinder; the pin is configured to move from the second position to the first position to push the residual resin toward the injection space.

Description

Technical Field

[0001] This utility model relates to a nozzle structure, and more specifically to a nozzle structure for injection molding. Background Technology

[0002] In recent years, research and development on improving energy efficiency has been ongoing to ensure access to affordable, reliable, sustainable, and advanced energy for more people. In this research, the injection molding of large resin products, considering the flowability of the resin material, requires a direct gate at the surface of the molded part. However, this direct gate placement can lead to differences in shrinkage due to the different cooling rates at the gate and its surrounding area, resulting in dents and reduced manufacturing quality. While a smaller gate diameter can minimize this cooling rate difference, for materials with poor flowability, such as polymethyl methacrylate (PMMA), a small gate diameter may cause shear heat generation, air bubbles, or prevent complete injection molding. Therefore, it is necessary to improve the nozzle structure for injection molding to overcome these problems. Utility Model Content

[0003] This utility model relates to a nozzle structure for injection molding, which can prevent shrinkage marks from occurring at the gate of injection molded products.

[0004] According to an embodiment of the present invention, a nozzle structure for injection molding includes: a resin supply channel leading to an injection space; and a valve needle disposed within the resin supply channel and used to block the resin supply channel. The valve needle includes an outer cylinder and a pin. The outer cylinder has a hollow structure inside. The pin is used to move along the inner surface of the outer cylinder within the hollow structure. The outer cylinder is used to move to a first position adjacent to the injection space to block the resin supply channel. The pin is located at a second position further away from the injection space than the first position to leave residual resin in the outer cylinder. The pin is used to move from the second position to the first position to push the residual resin into the injection space.

[0005] In an embodiment of the present invention, the inner diameter of the outer cylinder is smaller than the inner diameter of the resin supply channel.

[0006] In an embodiment of the present invention, after injection molding is completed, the outer cylinder moves to the first position and the pin is located at the second position; during the pressure holding process, the pin moves to the first position.

[0007] Based on the above, in the nozzle structure for injection molding of this utility model, the valve needle is configured to include an outer cylinder and a pin that can move within the outer cylinder. After injection molding, the outer cylinder moves forward to the gate to block the resin supply channel, while the pin remains at a position relatively far from the gate, leaving residual resin inside the outer cylinder. The outer cylinder located at the gate is equivalent to reducing the inner diameter of the gate, and the residual resin inside the outer cylinder is isolated from the resin from the resin supply channel, resulting in a lower temperature for the residual resin inside the outer cylinder. Therefore, during the holding pressure process, the pin moves forward to the gate, pushing the lower-temperature residual resin inside the outer cylinder through the smaller-diameter gate into the injection space, resulting in a smaller difference in cooling rate between the injection-molded product at the gate and its surroundings, and thus a smaller difference in shrinkage. Therefore, the nozzle structure for injection molding of this utility model can prevent shrinkage marks from forming on the injection-molded product at the gate. Attached Figure Description

[0008] Figure 1 This is a partial schematic diagram of an injection molding equipment according to an embodiment of the present invention;

[0009] Figures 2A to 2D Show Figure 1 The injection molding process of injection molding equipment.

[0010] Explanation of icon numbers

[0011] 100: Injection molding equipment;

[0012] 110: Nozzle structure for injection molding;

[0013] 112: Resin supply channel;

[0014] 114: Valve needle;

[0015] 1141: outer cylinder;

[0016] 1141a: Hollow structure;

[0017] 1142: Sales;

[0018] 120: Injection space;

[0019] 130: Cooling water circuit;

[0020] d1d2: inner diameter;

[0021] G: Gate;

[0022] P: Injection-molded product;

[0023] R: Resin;

[0024] R': Residual resin. Detailed Implementation

[0025] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same component reference numerals are used in the drawings and description to denote the same or similar parts.

[0026] Figure 1 This is a partial schematic diagram of an injection molding equipment according to an embodiment of the present invention. Please refer to it. Figure 1 The injection molding equipment 100 of this embodiment includes a nozzle structure 110 for injection molding and an injection space 120. The injection space 120 is, for example, a mold cavity formed by a mold. The nozzle structure 110 includes a resin supply channel 112 and a valve needle 114. The resin supply channel 112 leads to the injection space 120. One end of the nozzle structure 110 connected to the injection space 120 is a gate G. The valve needle 114 is disposed in the resin supply channel 112 and is used to block the resin supply channel 112. The valve needle 114 includes an outer cylinder 1141 and a pin 1142. The outer cylinder 1141 has a hollow structure 1141a inside. The pin 1142 is used to move along the inner surface of the outer cylinder 1141 within the hollow structure 1141a.

[0027] Figures 2A to 2D Show Figure 1 The injection molding process of injection molding equipment. Figure 1 With the valve needle 114 not blocking the resin supply channel 112, the injection molding equipment 100 can proceed as shown. Figure 2A As shown, resin R is injected into the injection space 120 through the resin supply channel 112 to form an injection-molded product P. After injection molding is completed, the injection molding equipment 100... Figure 2B The outer cylinder 1141 is moved to a first position adjacent to the injection space 120 by a cylinder or other suitable driving device to block the resin supply channel 112. At this time, the pin 1142 is located in a second position further away from the injection space 120 than the first position, leaving the residual resin R' in the outer cylinder 1141.

[0028] Next, in Figures 2B to 2D During the pressure holding process shown, the injection molding equipment 100 drives the pin 1142 from a cylinder or other suitable drive device. Figure 2B The second position shown gradually moves to Figure 2D The first position shown pushes the residual resin R' into the injection space 120. This holding pressure process is, for example, about 10 seconds or other suitable time length, which is not limited by this invention. Then, the injection-molded article P in the injection space 120 is allowed to cool to complete the injection molding process.

[0029] As described above, in the injection molding nozzle structure 110 of this embodiment, the valve needle 114 is configured to include an outer cylinder 1141 and a pin 1142 that can move within the outer cylinder 1141. After injection molding, the outer cylinder 1141 moves forward to the gate G, blocking the resin supply channel 112, and at this time, the pin 1142 remains at a position relatively far from the gate G, leaving residual resin R' in the outer cylinder 1141. The outer cylinder 1141 located at the gate G is equivalent to reducing the inner diameter of the gate G, and the residual resin R' in the outer cylinder 141 is isolated from the resin R from the resin supply channel 112, resulting in a lower temperature for the residual resin R' in the outer cylinder 1141. Therefore, during the holding pressure process, the pin 1142 moves forward to the gate G, pushing the lower-temperature residual resin R' in the outer cylinder 1141 through the smaller inner diameter gate G into the injection space 120, so that the difference in cooling rate between the injection molded product P at the gate G and its surroundings is smaller, resulting in a smaller difference in shrinkage. Therefore, the nozzle structure 110 for injection molding in this embodiment can prevent shrinkage marks from occurring at the gate G in the injection molded product P.

[0030] Specifically, the inner diameter d2 of the outer cylinder 1141 (indicated by...) Figure 2B The inner diameter d1 of one end of the resin supply channel adjacent to the injection space 120 is smaller than the inner diameter d1 (indicated by...). Figure 2A ).exist Figures 1 to 2A During the process of injecting resin R into the injection space 120, since the outer cylinder 1141 has not yet moved to the gate G, the gate G has a large inner diameter (i.e., the inner diameter d1 of the end of the resin supply channel 112 adjacent to the injection space 120). Therefore, even if the resin R is a material with poor flowability, such as polymethyl methacrylate (PMMA), it can still pass through the large-diameter gate G to avoid problems such as shear heat generation causing bubbles or inability to complete injection smoothly. Figures 2B to 2D During the pressure holding process shown, since the outer cylinder 1141 has moved to the gate G, the gate G has a smaller inner diameter (i.e., the inner diameter d2 of the outer cylinder 1141) to reduce the high-temperature resin area at the gate G, thereby reducing the difference in cooling rate between the injection molded product P at the gate G and its surroundings.

[0031] In this embodiment, the injection molding equipment 100 also includes a cooling water channel 130, which is located near the gate G of the injection molding nozzle structure 110, and can cool the residual resin R' in the outer cylinder 1141 to further reduce the difference in cooling rate between the injection molded product P at the gate G and its surroundings.

[0032] In summary, in the nozzle structure for injection molding of this invention, the valve needle is configured to include an outer cylinder and a pin that can move within the outer cylinder. After injection molding, the outer cylinder moves forward to the gate, blocking the resin supply channel, while the pin remains at a position relatively far from the gate, leaving residual resin inside the outer cylinder. The outer cylinder located at the gate effectively reduces the inner diameter of the gate, and the residual resin inside the outer cylinder is isolated from the resin from the resin supply channel, resulting in a lower temperature for the residual resin inside the outer cylinder. Therefore, during the holding pressure process, the pin moves forward to the gate, pushing the lower-temperature residual resin inside the outer cylinder through the smaller-diameter gate into the injection space, resulting in a smaller difference in cooling rate between the injection-molded product at the gate and its surroundings, and thus a smaller difference in shrinkage. Therefore, the nozzle structure for injection molding of this invention can prevent shrinkage marks from forming on the injection-molded product at the gate.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A nozzle structure for injection molding, characterized by, comprising: a resin supply passage leading to a molding space; and a valve needle disposed in the resin supply passage and serving to block the resin supply passage, the valve needle including an outer cylinder having a hollow structure inside and a pin serving to move along an inner surface of the outer cylinder inside the hollow structure, the outer cylinder serving to move to a first position abutting the molding space to block the resin supply passage, and the pin being located at a second position farther from the molding space than the first position to leave residual resin inside the outer cylinder, the pin serving to move from the second position to the first position to push the residual resin toward the molding space.

2. The nozzle structure for injection molding according to claim 1, wherein an inner diameter of the outer cylinder is smaller than an inner diameter of the resin supply passage.

3. The nozzle structure for injection molding according to claim 1, wherein after completion of injection molding, the outer cylinder moves to the first position and the pin is located at the second position, during a holding process, the pin moves to the first position. ​

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