Main product of information channel monitor is shown in Figure 1. Maximum size of product is 168.00 mm * 121.70mm * 62.35 mm, average thickness of plastic part is 1.70 mm, material of plastic part is PC, shrinkage rate is 1.004, and weight of plastic part is 133.08 grams. Technical requirements for plastic parts are that there must be no defects such as peaks, underfilling of injection molding, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, etc.

 

Figure 1 Product diagram of main body of information channel monitor
It can be seen from Figure 1 that plastic part is a rectangular box with a large height. The two large sides are parallel to each other. One of large sides has a 0.2-deep partial sinking plane, which is used to affix trademark. Top corners of the two large surfaces each have a rotating shaft, which is used to assemble end cover and act as a hinge shaft. Coaxiality is required to be ø0.05. In summary, the two large surfaces must be designed with large sliders. Two outer and two end surfaces have different shapes, there are various square holes and round holes on the surface, and it is also necessary to design a large-scale slider to pull core as a whole. There are multiple hollow windows and small holes on the top of plastic part, which affect flow of plastic during injection molding.
Size of plastic part is large, and four-sided slider core pulls, which determines mold design cavity ranking as 1 cavity. Mold design drawing is shown in Figure 2. Mold base is a standard mold base DCI4045, size of slider is larger, shovel chooses original body, all four large sliders higher than parting surface are wrapped in A plate. This type of plastic part has a large side glue area. Under action of injection pressure, sliding block of mold has a great tendency to separate to four sides. Shovel is required to be strong enough and extremely powerful. Therefore, it is necessary to select mold base with sufficient strength when designing mold.
Since plastic parts are wrapped with large sliding blocks on four sides, design of gating system must be glued from top surface. Therefore, a three-plate mold was designed according to needs, and gating system used a small nozzle to a large nozzle to inject glue from multiple window edge side gates on the top surface of plastic part. Gate is 4 points. Top surface of plastic part has multiple buttons, indicator lights, and LED screen display windows, which need to be flat. Therefore, thickness of side gate needs to be lower than plastic position of plastic part for easy trimming.

 

Figure 2 Mould diagram

 

Figure 3 Slider diagram
All four sliders are driven by inclined guide posts, inclined surface and bottom surface of slider are all inlaid with wear plates. Wear-resistant plates are generally made of oil steel 2510, after heat treatment, hardness is HRC56. Surface of wear-resistant plates needs to be processed with oil grooves. Oil grooves have two types of diamonds composed of intersecting lines and intersecting circles. Depth of oil groove is 0.8, no matter what kind of structure oil groove is, do not break to edge when processing, that is, leave a certain distance between pattern and four sides of wear plate. Purpose of this is that in actual use, oil stains generated by movement and wear of slider will not escape, so that product will not be contaminated.
Height of plastic part is very large, and plastic part has a great tightening force on the movable mold during injection molding. For plastic parts of this type of structure, it is not feasible to simply use a thimble to eject it. Because ejection stroke is large, plastic part is sleeved on ejector pin when ejecting, and it is difficult to take it out. Larger ejection force often causes whitening of plastic parts. For this reason, push blocks are designed on the edge of long side of plastic part, and two push blocks are designed on each long side. Main ejector element of this set of molds is a push block, supplemented by a small amount of ejector pins.

 

Auxiliary device of mold plays a very important role in normal operation of mold. Lock module is an indispensable accessory for mold hoisting and transportation. Lock module of three-plate mold needs to be lengthened to lock each mold plate that may be separated. Lock module must be painted with red paint to remind operator to remove it before opening mold. Mold foot is an auxiliary component that protects mold from touching ground. It depends on height of components exposed on the surface of mold such as water nozzle at the bottom of mold. When there are components such as an oil cylinder at the bottom of mold, mold feet need to be heightened. Ejector rod in K.O hole can protect ejector plate from deformation, reduce ejection stroke, and shorten injection cycle.