Cadcam design of injection mold for the hottest bu

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Key injection mold cad/cam design

the wide application of plastic products has led to the rapid development of injection mold, and the requirements for injection mold design and manufacturing are becoming higher and higher. The traditional manual design and manufacturing methods have greatly restricted the development of production. The development of computer-aided design/computer-aided analysis/computer-aided manufacturing (cad/cae/cam) technology meets the objective and practical requirements, and has achieved remarkable economic benefits. Taking the key as the research object, this paper analyzes the injection molding process of plastic parts with CAE analysis software Moldflow, and determines the best gate position, gating system form, cooling system and molding process parameters. Based on pro/e software, the three-dimensional parting of the product is carried out, and the cavity and core structure are determined. On this basis, the simulation processing and NC programming of the main parts of the mold are carried out

1 key structure analysis

keys belong to small plastic parts, and the molding material is ABS. As shown in Figure 1, its wall thickness is 1.6mm, and its overall dimension is 22.4 mm x 9.4mm x 7.25mm. The shape and structure of the keys are relatively complex, with rounded corners around. The surface of plastic parts shall be beautiful, bright and clean, without obvious welding marks, silver wires and flow marks, and without obvious warpage and deformation. Both sides of the plastic parts are provided with side holes, and a side core pulling mechanism is required. The side core can be set and driven by the side slider and inclined guide post, which is convenient for parting. In addition, in order to successfully remove the plastic part from the formed part, sufficient demoulding slope must be designed along the demoulding direction on the inner and outer surfaces of the plastic part. The corners of plastic parts should adopt arc transition as far as possible, so as to increase the strength of plastic parts, improve the filling fluidity, and increase the aesthetic degree

Figure 1 key product figure

2 key CAE analysis

the three-dimensional model of the key created by pro/e is imported into Moldflow through IGES file conversion format for plastic forming process simulation analysis. In the pre-processing process, the lattice division of the model and the selection of molding materials are required

2.1 analysis and determination of the best gate location

when injection molding, it is necessary to determine the gate location first. The gate location has a direct impact on the product quality. It should be set at the part with thick section of the plastic part, so that the melt flows from the thick section to the thin section, and the location should be set to avoid weld marks on the surface of the plastic part, and finally should be conducive to the discharge of gas in the cavity. The best gate location is shown in Figure 2

Figure 2 optimal gate location

2.2 establishment of gating system

according to the analysis of the optimal gate location and the use requirements of plastic parts, this design adopts point gate, as shown in Figure 3. Due to the large pressure difference between the front and rear ends of this kind of gate, it can increase the shear rate of plastic melt and produce large shear heat, resulting in the decrease of surface drillability of melt and the increase of fluidity, which is conducive to the filling of mold cavity

Figure 3 gating system simulation

2.3 filling analysis simulation

Figure 4 shows the analysis results of mold filling time. It can be seen from Figure 4 that the filling time is 1.695s, and the melt reaches both ends of the mold cavity almost at the same time, which can meet the requirements

Figure 4 filling analysis simulation

2.4 cooling analysis simulation

injection mold can be used as a heat exchanger. If the cooling medium cannot take away the heat that must be taken away in time and effectively, and uniform rapid cooling cannot be achieved, the thermal balance cannot be maintained within a molding cycle, which will cause stress in the plastic part and lead to deformation or cracking, so that stable molding cannot be carried out. Therefore, cooling analysis is necessary. According to the shape of plastic parts and the setting of other parts of the mold, the cooling system shown in Figure 5 is designed. It can be seen from Figure 5 that the temperature difference between the inlet and outlet of cooling water is 0.06 ℃, which meets the requirement that the temperature difference of cooling water is less than 2.5 ℃. The influence of the cooling system on the temperature of plastic parts is shown in Figure 6. The surface temperature of plastic parts is basically the same, and the cooling is more uniform, which is conducive to improving the shape accuracy of plastic parts

Figure 5 cooling water inlet and outlet temperature simulation

2.5 warpage analysis simulation

Figure 7 shows the overall deformation and deformation in all directions. It can be seen from Figure 7 that the deformation in the overall and X directions is large, while the deformation in the Y and Z directions is relatively small

Figure 7 warpage analysis simulation

2.6 pressure distribution in the cavity

figure 8 shows the cavity pressure distribution at the moment when the melt fills the cavity. It can be seen from figure 8 that the pressure distribution is relatively uniform

figure 8 pressure distribution in the cavity

2.7 mode locking force

Figure 9 is the time curve of mode locking force. It can be seen from Figure 9 that the maximum clamping force required is about 0.5226t, so a suitable injection machine can be selected according to this value to obtain sufficient clamping force

3 3D parting based on pro/e

due to the large number of curved surfaces of plastic parts, it is difficult to design the mold directly according to the product engineering drawing. Therefore, using pro/e for 3D parting to generate 3D cavity and core can avoid the 2D and 3D spatial imagination of mold designers for complex cavity and core in traditional design methods, reduce the design difficulty and mold processing difficulty, and improve the design accuracy of the mold

the steps of 3D parting are as follows:

(1) create a mold model. Figure 10 shows the plastic parts transferred into the cavity of pro/e mold. This mold adopts the first mock examination with two cavities

the first mock examination with two cavities

(2) create a blank. Create a blank of 80mmx48mm by stretching, and make it reach the position 10~15mm away from the notch predicted by the cooling expert, which is good x 40mm

(3) set the shrinkage. The accuracy requirements of key plastic parts are general. The raw material is ABS plastic material with abnormal pendulum position, and its shrinkage range is small. According to the full-size shrinkage, the shrinkage is set to 0.016

(4) create a runoff surface

(5) design of gating system

(6) create casting. First, the mold volume block is divided by the parting surface, the side core volume block, the main core and cavity volume block are divided, and the mold components are extracted, and finally the casting is created

(7) add to the cooling system. The final three-dimensional split exploded view

4 NC machining of mold cavity

guide the generated mold cavity into MasterCAM software. After setting the machining parameters and tool machining path, using the part machining simulation function provided by MasterCAM software system, we can observe the cutting process, detect whether the setting of process parameters is reasonable, whether there is interference in the actual NC machining of parts, and finally generate the tool position file, NC code is generated by the post processor

5 conclusion

mold cad/cae/cam technology is an important milestone in the development of mold technology. In the mold development, pro/e software is used to establish the product solid model, CAE technology is used to simulate and analyze the injection molding process, and then optimize the process parameters and mold structure. At the same time, the mold core and cavity are generated according to the product model. Using CAM software to program and process can effectively shorten the manufacturing cycle, improve production efficiency and solve the manufacturing bottleneck. Through cad/cae/cam technology, product quality can be improved, product development cycle can be shortened, and design and development costs can be effectively reduced, so as to enhance the competitiveness of enterprises in the market. (end)

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