Design of injection mold for cyclone catcher body
Time：2022-03-22 08:39:57 / Popularity： / Source：
As can be seen from Figure 1, plastic part structure is a small functional structural part, with left-right symmetry, small size and high precision. All parts requiring high precision are marked with dimensional tolerances. Two shafts with a diameter of Ø4.97±0.15 need to control diameter and maintain coaxiality. Mold release of groove at one end of plastic part needs to design slider core. Since plastic parts are symmetrical from left to right, structure of slider can be designed as a partial Hough structure. Bone position on the back of plastic part is deep, and height difference is large, so it is necessary to design insert processing.
In the past, mold design of precision plastic parts was designed according to principle of motherhood. That is, precision and finish of mold are about 2 levels higher than that of plastic parts. However, with advancement of technology, we will find that precision of machine tools and mold processing has reached a very high level, precision requirements of plastic parts are also getting higher and higher. Continuing to improve machining accuracy of mold has no obvious effect on accuracy of plastic parts, but will only increase cost of mold. Therefore, in order to improve accuracy of injection molded parts, it is necessary to find factors that affect accuracy of precision plastic parts, analyze these influencing factors, and solve main problems in order to design precision plastic parts that meet customer requirements.
For precision molds, gating system design and cooling water design, use of computer-aided design and mold flow analysis of advanced software to guide mold design will achieve twice result with half effort, and must be used.
Use big data to accumulate experience in different plastic molding. For same type of plastic parts, compared with its historical experience, use of big data can form accurate injection molding conditions to guide injection molding production.
Mold review of product design engineer and mold design engineer should be carried out in time before mold design. Mold design engineers need to master plastic product design standards of various countries in the world. European molds generally use DIN standards; United States and North American countries mostly use SPI standards; Japanese customers mostly use Japanese communication technology standard CES M-77012 standard, which specifies dimensional tolerance of plastic molded parts in communication equipment. But it is not suitable for gear teeth, threads and more precise mating parts.
When precision injection molding, it is necessary to pay attention to high injection pressure. Generally speaking, pressure of precision injection molding needs to be increased to 180MPa ~ 250MPa, and even higher for some plastic parts. Because of increased pressure, dimensional stability of plastic parts is improved and deformation of plastic parts is reduced.
During injection molding, if a faster injection speed is used, not only can products with complex shapes be molded, but also dimensional tolerances in plastic parts can be reduced. Therefore, when precision injection molding products, fast injection speed is required.
Temperature has a great influence on molding quality of plastic parts. For precision injection, it is necessary to precisely control temperature of mold and temperature of barrel. Cooling system achieves a balanced cooling water circuit. Fixed mold plate adopts addition of heat insulation board to reduce exchange of heat between mold and injection molding machine.
In design of precision plastic parts, in addition to choosing plastics that are conducive to precision molding, it is also necessary to be able to control injection molding process. When molding PC materials, it is necessary to choose a small screw injection molding machine for precise control. On mold side, mold needs to have sufficient stiffness and strength. This set of molds adopts a non-standard thimble plate design, as shown in Figure 7. Mechanism of thimble plate is recessed in the middle in the plane, showing an X shape. Square iron is widened in the middle part, and rigidity of movable mold part is obviously enhanced.
Cavity ranking of precision molds cannot exceed 4 holes. This set of molds adopts a cavity design of 1 out of 2. Layout of cavity is shown in Figure 2. Gate design is shown in Figure 6. After molten plastic is injected onto parting surface with a single hot nozzle, a latent gate is designed, and a bone position is designed from movable mold of plastic part.
Use of garbage nails in European molds is gradually reduced, and garbage grooves are replaced. As shown in Figure 8, garbage grooves are milled on the face where thimble bottom plate is combined with bottom plate, and depth of milling groove is 1mm.
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