Precise forming design method of polyethylene elbow pipe connector

Abstract

The invention discloses a precision forming design method for a polyethylene elbow joint. The method comprises the following steps: treating a plastic model; the plastic part is subjected to grid division treatment, free edges and multiple edges are zero, incorrect units are zero, and intersecting units and overlapping units are zero; simulating filling time; the single-cavity forming period is 4.005 s, and the period is suitable for production; simulating deformation; if the size of the warped edge is larger, the quality of the product does not reach the standard, so that the deformation amount of the product needs to be controlled, and the cooling effect plays a crucial role; performing simulated cooling; the mold cooling effect can influence the molding period of a plastic part, and the temperature difference value of an inlet and an outlet of a cooling pipeline should be 6.47 degrees. Through optimization design of forming parameters, cooling design and pouring gate design, a plastic part product with the best precision and quality is obtained, and a designer can better optimize the product structure and control the product quality.

Description

Technical Field

[0001] The present invention relates to the technical field of injection molds, and particularly to a precision forming design method for polyethylene elbow joints. Background Art

[0002] The production level of molds is closely related to the service life and quality of products and the R & D capabilities of new products. It is also the primary criterion for measuring manufacturing levels. As is well known, the improvement of China's current industrial level is inseparable from the increasing development of the mold industry. As the most basic process equipment, in many industrial chains, mold parts meet the use requirements of more than 80% of products. The wide range of industries it involves further illustrates its importance, which has attracted the attention of enterprises and researchers. What makes it different from other processing methods is that the products obtained by its processing have particularly high precision, short processing cycles, low material waste rates, high utilization rates, and more considerable product profits. Moreover, with the development of economic globalization, the domestic industrial development will also encounter many new challenges. There are many methods for processing products using molds, and injection molding is just one of the more mature and common ones. So far, the annual output of injection molds basically accounts for more than 60% of the total number of molds, and it can be widely used in high-end aerospace equipment, automotive instrument equipment, etc. Currently, this data is still showing an upward trend, indicating that the market demand for plastic molds has a good prospect.

[0003] With the continuous enhancement of China's comprehensive national strength, China's industry has also developed rapidly. Currently, majors such as mold design and manufacturing and material forming have become popular majors in domestic universities, indicating that the majors of mold manufacturing and design have received more attention and there are more related practitioners. With the development of the times and the change of trends, high-quality and beautiful plastic products will be favored by more consumers in the future. At the same price, people hope to obtain both beautiful plastic products and multifunctional plastic products. Currently, according to the existing technology, although some difficulties and problems have been solved in the process of mold design and manufacturing, there are still some problems that cannot be underestimated in the actual injection molding process, mainly manifested in mold forming problems, exhaust deformation problems, cooling problems, mold service life problems, etc. Therefore, it is very necessary to continuously research and optimize mold forming technology. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention aims to provide a precision forming design method for polyethylene elbow joints. The present invention uses Moldflow software to perform mold flow analysis on plastic parts. Through the present invention, the forming parameters, cooling design, and gate design can be optimized, and plastic part products with the best precision and quality can be obtained, which is more conducive to designers to optimize the product structure and control the product quality.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A precision forming design method for a polyethylene elbow joint, the method comprising the following steps:

[0007] S1 Plastic model processing; the plastic part is subjected to mesh division processing, with free edges and multiple edges being zero, incorrect elements being zero, and intersecting elements and overlapping elements being zero;

[0008] S2 Simulating filling time; the single-cavity forming cycle is 4.005 s for forming, and the cycle is suitable for production;

[0009] S3 Simulating deformation; the larger the warpage size, the less qualified the product quality, so it is necessary to control the deformation amount of the product. Among them, the cooling effect plays a crucial role. Through mold flow analysis, the deformation amount of the plastic part can be obtained as 5.568;

[0010] S4 Simulating cooling; the cooling effect of the mold will affect the forming cycle of the plastic part. The design of the cooling system is crucial in the design of the whole set of molds. The plastic part is injected into the cavity at a high temperature. If the temperature is too high, it will cause inaccurate dimensions of the plastic part and a long injection time. The temperature difference between the inlet and outlet of the cooling pipeline is 6.47°.

[0011] It should be noted that in the gating system, the position of the sprue is generally at the entrance of the mold. Usually, a horizontal type injection molding machine will use a direct gate type sprue. The sprue is the main channel for plastic flow. Generally, it does not need to be too long. However, there will be solution residues on the sprue. In order to pull it out together during demolding, the sprue shape is generally designed as a conical shape.

[0012] It should be noted that the gate of the part elbow joint is designed in the middle area of the plastic part. Through mold flow analysis and optimization design, the gate shape is preferably the direct gate method to prevent the solution from flowing back after injection. The direct gate is most suitable for the forming of large products. The gate distance is short, and it can quickly fill large products.

[0013] It should be noted that the cooling of the cavity and the core is designed around the mold, and it is designed as a circular cooling water flow. The circular water flow can control the temperature of the entire cavity and is more convenient for the cooling of the mold.

[0014] The beneficial effects of the present invention are as follows: mainly based on the process of designing an injection mold for an elbow joint, the best process parameters are obtained by using orthogonal experiments and Moldflow simulation analysis, the number and arrangement of the cavities of the mold can be further determined, and a suitable parting surface is selected. Calculate and design the main forming structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of a pipeline plastic part simulated and designed by the present invention;

[0016] Figure 2 It is a schematic diagram of the grid division of the plastic part in the present invention;

[0017] Figure 3 It is a schematic diagram of the filling time of the plastic part in the present invention;

[0018] Figure 4 It is a schematic diagram of the deformation analysis of the plastic part in the present invention;

[0019] Figure 5 It is a schematic diagram of the cooling simulation of the plastic part in the present invention. Specific implementation manners

[0020] The present invention will be further described below in conjunction with the drawings. It should be noted that this embodiment is based on the present technical solution, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to this embodiment.

[0021] The present invention is a precision forming design method for a polyethylene elbow joint, and the method includes the following steps:

[0022] S1 Plastic model processing; the plastic part is subjected to grid division processing, with free edges and multiple edges being zero, incorrect units being zero, and intersecting units and overlapping units being zero;

[0023] S2 Simulating the filling time; the single-cavity molding cycle is 4.005 s for molding, and the cycle is suitable for production;

[0024] S3 Simulating deformation; the larger the warpage size, the less qualified the product quality. Therefore, it is necessary to control the deformation amount of the product. Among them, the cooling effect plays a crucial role. Through mold flow analysis, the deformation amount of the plastic part can be obtained as 5.568;

[0025] S4 Simulating cooling; the cooling effect of the mold will affect the molding cycle of the plastic part. The design of the cooling system is crucial in the design of the entire set of molds. The plastic part is injected into the cavity at a high temperature. If the temperature is too high, it will cause inaccurate dimensions of the plastic part and a long injection time. The temperature difference between the inlet and outlet of the cooling pipeline is 6.47°.

[0026] Furthermore, in the gating system of the present invention, the position of the sprue is generally at the entrance of the mold. Usually, a horizontal-type injection molding machine will use a direct gate type sprue. The sprue is the main channel for plastic flow and generally does not need to be too long. However, there will be solution residues on the sprue. In order to pull it out together during demolding, the sprue shape is generally designed as a conical shape.

[0027] Furthermore, the ingate of the part elbow joint of the present invention is designed in the middle area of the plastic part. Through mold flow analysis and optimization design, the shape of the ingate is preferably a direct gate to prevent the reverse flow of the solution after injection. The direct gate is most suitable for the molding of large products. The gate distance is short, which can quickly fill large products.

[0028] Furthermore, the cooling of the cavity and the core of the present invention is designed around the mold and is designed as annular cooling water channels. The annular water channels can control the temperature of the entire cavity and are more convenient for the cooling of the mold.

[0029] Embodiment

[0030] Since the mold performs injection molding work for a long time, there are high requirements for its life and quality. The main runner is in contact with high-temperature solution for a long time and there are repeated injection operations, so it is extremely vulnerable to damage inside the runner. Therefore, when making the main runner, the material hardness should be considered. At the same time, a sprue bushing is used to cooperate with the main runner for injection. The use of the sprue bushing can minimize the damage to the main runner to the greatest extent. The sprue bushing is processed with high-quality structural steel material, and 45 steel is selected.

[0031] In the gating system, the position of the main runner is generally at the entrance of the mold. Usually, horizontal injection molding machines use direct gate type main runners. The main runner is the main channel for plastic flow and generally does not need to be too long. However, there will be solution residues on the main runner. In order to pull it out together during demolding, the shape of the main runner is generally designed as a conical shape. According to the design principle of the main runner and the dimensional relationship between the main runner and the injection machine nozzle, the following formula is obtained:

[0032] Radius of the main runner spherical surface = Radius of the injection machine nozzle ball head + (1 - 2) mm

[0033] SR2 = SR1 + 1 - 2 mm = 12 + 1 = 13

[0034] Small end diameter of the main runner = Diameter of the injection machine nozzle orifice + (0.5 - 1) mm

[0035] d = d1 + (0.5 - 1 mm) = 6 + 1 = 7

[0036] The flow state of the cooling water in the pipeline has a significant impact on the cooling effect. The heat transfer effect in the turbulent state is 10 - 20 times higher than that in the laminar state. Specifically, when the water flow rate is 5.08×10-3 m 3 / min, to ensure that the cooling water is in a fully turbulent state, the minimum water flow velocity should be vmin = 1.66 m / s, and the pipeline diameter d = 10 mm.

[0037]

[0038] Calculation of heat conduction area and length and number of cooling water channels

[0039] The heat conduction area required when cooling the mold with water flow is [5]:

[0040]

[0041] In the formula: Aw is the heat conduction area (m 2 );

[0042] hw is the heat transfer coefficient of the cooling water to the inner wall of its channel [W / (m 2 ·°C)];

[0043] Δθ is the difference (°C) between the average temperature of heat conduction and the average temperature of the cooling water.

[0044]

[0045] The cooling of the cavity and the core is designed around the product and is designed as annular cooling water flow. The annular water flow can control the temperature of the entire cavity and is more convenient for the cooling of the mold.

[0046] For those skilled in the art, various corresponding changes and deformations can be given according to the above technical solutions and concepts, and all such changes and deformations should be included within the protection scope of the claims of the present invention.

Claims

1. A precision forming design method for a polyethylene elbow joint, characterized in that The method includes the following steps: S1 Plastic model processing: The plastic part is subjected to mesh division processing, with free edges and multiple edges being zero, incorrect elements being zero, and intersecting and overlapping elements being zero; S2 Simulating filling time: The single-cavity molding cycle is 4.005 s for molding, and the cycle is suitable for production; S3 Simulating deformation: The larger the warpage size, the less qualified the product quality. Therefore, it is necessary to control the deformation amount of the product. Among them, the cooling effect plays a crucial role. Through mold flow analysis, the deformation amount of the plastic part can be obtained as 5.568; S4 Simulating cooling: The cooling effect of the mold will affect the molding cycle of the plastic part. The design of the cooling system is crucial in the design of the whole set of molds. When the plastic part is injected into the cavity at a high temperature, too high a temperature will cause inaccurate dimensions of the plastic part and a long injection time. The temperature difference between the inlet and outlet of the cooling pipeline is 6.47°.

2. The precision forming design method of the polyethylene elbow joint according to claim 1, characterized in that In the gating system, the position of the sprue is generally at the entrance of the mold. Usually, a horizontal injection molding machine will use a direct gate type sprue. The sprue is the main channel for plastic flow and generally does not need to be too long. However, there will be solution residue on the sprue. In order to pull it out together during demolding, the shape of the sprue is generally designed as a conical shape.

3. The precision forming design method of the polyethylene elbow joint according to claim 1, characterized in that The gate of the part elbow joint is designed in the middle area of the plastic part. Through mold flow analysis and optimization design, the gate shape is preferably the direct gate method to prevent the solution from flowing back after gating. The direct gate is most suitable for the molding of large products. The gate distance is short, which can quickly fill large products.

4. The precision forming design method of the polyethylene elbow joint according to claim 1, characterized in that The cooling of the cavity and the core is designed around the mold and is designed as annular cooling water circulation. Annular water circulation can control the temperature of the entire cavity and is more convenient for the cooling of the mold.

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