Design of Injection Mould for Notebook C Shell
The notebook shell is divided into four parts: A, B, C and D. Notebook A shell: the top cover of the display screen, the large cover, is the A shell, as shown in Figure 1(a). Notebook B shell: the frame inside the display screen (when looking at the screen, the side next to it), as shown in Figure 1(b). Notebook C shell: The shell next to the keyboard is the C shell. The position of the hand rest is shown in Figure 1(c). Notebook D shell: The bottom of the machine is in contact with the desktop at the D shell, as shown in Figure 1(d). The notebook shell is the carrier and protective shell of the main board, processor and other functional operating components. It integrates a series of importance such as process design, materials, volume control, weight control, heat dissipation control, sturdiness, safety, and environmental protection. Notebook shell materials include ABS engineering plastics, magnesium aluminum alloy, titanium alloy, carbon fiber alloy, PC-GF (polycarbonate PC), etc. Among them, PC+ABS and aluminum-magnesium alloy are the most common, and these two are also the most widely used. Notebook shell material. This article introduces the mold design of the notebook C shell made of PC+ABS.
2. Product analysis
The product picture of the notebook C shell is shown in Figure 1. The maximum size of the plastic part is 276.50 mm X 228.30 mm X 9.30 mm, the average thickness of the plastic part is 1.50mm, the thickness of the button area is 1.20 mm, and the weight of the plastic part is 78.5 grams. The material is PC+ABS, the shrinkage rate is 0.37%.
The appearance requirements of plastic parts are that there must be no injection defects and no warpage or deformation of the plastic parts. PC+ABS combines the advantages of PC and ABS. Compared with PC, PC+ABS alloy mainly improves melt fluidity, formability, electroplating and appearance. Compared with ABS, it mainly improves the heat resistance, impact resistance and rigidity of thin-walled products.
PC+ABS must be dried before molding to reduce the water content of the material to below 0.05%, preferably below 0.02%, in order to improve the processing stability and mechanical properties of the material. Use a mold temperature machine to control the mold temperature when molding PC+ABS. The recommended mold temperature is 50-80°C. Higher mold temperature tends to produce good flow, higher weld line strength, and lower product internal stress, but the molding cycle will be prolonged. If the mold temperature is lower than recommended, it will cause high internal stress and damage the best performance of the part. As far as the surface of the part and the cycle period are concerned, when the mold temperature is in the middle of the recommended temperature range, better results can be expected.
The two parts of the plastic parts need to be designed with slider core pulling, and the two buckles at the edge of the window of the middle mouse touch screen need to be designed with inclined top molding, as shown in Figure 2.
3. Key points of mold design
3.1 Number of cavities
The size of the plastic parts is large, and the injection molding machine tonnage required is large, so only one cavity layout can be designed. The mold design is shown in Figure 3. The mold base is FCI4550A80B110C120. The four sides are equipped with zero-degree side locks for precise positioning. The selected injection molding machine is a 250-ton injection molding machine. After calculation, the plasticizing capacity and clamping force meet the requirements.
3.2 Design of pouring method
The plastic parts are large in size and belong to flat thin-walled shells. The flow length of plastic parts is relatively large. Therefore, it is critical to determine the location and number of gates. In the mold design, 8 points of glue was selected, see the mold design drawing. Among them, the glue is injected into the gate at 6 o'clock in the keyboard position, and the gate parameters are shown in Figure 7. The other two points are the large nozzle lap glue feeding, as shown in Figure 8.
3.3 Lateral core pulling system design
The 2 sliders are smaller in size, so choose the rear mold slider driven by the inclined guide column to pull the core. The two inclined roofs are the inclined roofs with T-slot sliding.
3.4 Insert design
The size of the front and rear mold cores is large, and it is more difficult to directly insert into the fine frame of the template. Therefore, the front and rear mold cores are respectively designed with compression blocks, based on the reference angle, two sides away from the reference angle, the mold frame is increased by 1mm, Press in the squeeze block. There are two inlay methods for the small inserts of the back mold core, one is the hanging table and the other is the taper, each with its own characteristics. The design of the small insert hanging table has many advantages: one is that it eliminates the drilling and tapping of the mold base and the insert; the second is to simplify the work of mold assembly; the third is to avoid the possibility of missing screws. The main points of the hanging platform design are as follows: (1) The hanging platform of the insert should be selected on the long side of the insert, while avoiding the curved part. (2) It is necessary to ensure that the hanging table and its location can be ground or wire-cut. (3) The short hanging platform should avoid the flat top rod to avoid interference. (4) In short, the design of the hanging table must consider the processing technology, not arbitrarily design. (5) When there is a water-carrying rubber ring at the bottom of the insert, do not use a hanging platform, but fix it with screws to prevent water leakage.
