Design of injection mold for exterior decoration shell of sound box
The outer shell of the speaker is shown in Figure 1. The maximum size of the product is 132.61 mm x 78.21 mm x 42.81 mm, the average thickness of the plastic part is 1.80 mm, the material of the plastic part is ABS, the shrinkage rate is 1.005, and the quality of the plastic part is 24.17 grams. . The technical requirements for plastic parts are that there must be no defects such as peaks, dissatisfaction with injection molding, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, etc.
The structure of the plastic part is a heterosexual shell, and the design of the plastic part and the 3D mold is shown in the attached 3D drawing. The production batch of plastic parts is relatively large. Considering the structure of the plastic parts and the existing injection molding machine tonnage, the mold design cavity ranks 1 out 1. When the tonnage of the injection molding machine is large, you can also choose the cavity rank 1 out 2. The three sides of the plastic part have flanges facing the movable mold, and the edge of the largest side has holes to form an inverted buckle. The edges on the two outer sides are perpendicular to the top surface, that is, the two sides also need to be designed with sliders Core-pulling. Therefore, the difficulty of mold design is the design of three sliders.
When designing the mold, it is necessary to make the demolding angle for the plastic part. The plastic material is different, the bone height is different, and the angle value of the demolding angle is different. If the demolding slope is too large, it will affect the appearance of the plastic part; if the demolding slope is too small, the plastic part will be dragged or deformed during the demolding process. The product design engineer sometimes does not design the draft angle in the product 3D drawing. When designing the mold, the mold designer needs to work with the product design to determine the mold ejection slope of the plastic part.
In this set of molds, the two sides of the outer side of the plastic part have no demolding inclination, so when designing the mold, it is necessary to design the slider forming, that is, the slider 2 and the slider 3. These two sides must not be designed for demolding oblique Therefore, mold design engineers need to make correct judgments.
The 3 side of the plastic part needs to be designed with a slider, and the slider is designed on the operating side, the opposite operating side and the ground. There is no slider on the sky side, and the gate is designed at the center of the mold. The gate is a horn gate, which can be automatically broken when the mold is opened, and the mold can be automatically injected. The positioning ring and K.O hole of the mold are eccentrically designed to be 30mm. The three sliders of the mold are driven by oblique guide posts. The glue position part is designed with slider inserts, and the slider inserts are fixed on the slider seat from the side.
There are two undercuts on the back of the plastic part that need to be designed for inclined top demoulding. Therefore, the ejection of plastic parts adopts thimble, cylinder and inclined ejection.
The design of the injection mold cooling system is often regarded as a secondary issue. Not enough attention has been paid to the size and structural design of the cooling system. The unreasonable design of the cooling system will cause internal stress for small plastic parts, and deformation and even stress cracking for large plastic parts with thin walls. Moreover, insufficient cooling will lead to prolonged molding cycle, thereby reducing production efficiency. For the cooling of injection molds, the most efficient is direct water transport. As shown in Figure 2, the movable and fixed molds of the mold are designed for direct water transport.
There is a basic difference in cooling between the molds for mass production of plastic parts and the molds for the production of precision plastic parts. For molds for mass production of plastic parts, in order to shorten the cycle time, it is best to use "quick" cooling, which may cause large dimensional fluctuations, rough and uneven structures, and large internal stress in the plastic parts. "Quick" cooling means that the distance between the cooling channel and the cavity is very close, and the mold temperature is low. For the production of precision parts, narrow tolerance bands and good mechanical properties are required. This requires "slowing down" the cold. Taking into account the filling of the mold and the mechanical properties of the plastic part, it is ideal that the mold temperature is close to the melting point temperature at the moment of injection, and then slowly cooled to the demolding temperature. The outer shell products of loudspeakers are produced in large batches, and the cooling system is designed to pursue the goal of rapid cooling.
ABIS MOLD TECHNOLOGY CO.,LTD
Daisy Wang (Sales Engineering)
M: +86-150 1652 6799
E: daisy@abismold.com
A: Building B#,YingKeli Industrial Part, LongDong Community, LongGang District, Shenzhen, China
WhatsApp: +86 136 8261 9739
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