Injection Mold Design Scanner Shutter
Scanner shutter products have a maximum external dimensions of 121.80 mm x 88.86 mm x 25.77 mm, plastic parts with an average thickness of 2.70 mm, plastic parts of PC+ABS, a shrinkage of 1.005, and a plastic part of 18.35 grams. There are no defects such as peaking, injection molding, flow pattern, pores, warpage, silver, cold, spray, and bubbles.
As shown in the product diagram of the scanner shutter, the plastic parts are complex brackets. Although there are no complicated curved surfaces, the height is low and the shape is complicated. Another feature of the plastic part is that the shape is bilaterally symmetrical. In the product, the plastic part bears the functional support and is the key part inside the product. There are 4 vertical vertical walls in the middle of the plastic parts, and there is a ø3.2 through hole on each of them. Here, the 4 holes must ensure the concentricity requirements, which is convenient for the rotation of other related parts after assembly. Plastic parts U-shaped openings at both ends, respectively, have a wear-through position hook for assembling other originals, and a U-shaped bottom has a hook, all of which require accurate dimensions. Therefore, plastic parts have higher requirements on geometric tolerances. Plastic material PC+ABS, commonly known as plastic alloy, combines the excellent properties of two materials, namely the formability of ABS material and the mechanical properties, impact strength and temperature resistance, UV resistance (UV) of PC. Difficulties in mold design are the choice of mold opening direction, the design of the parting surface and the design of the slider core mechanism of the four through holes. The parting surface analysis of plastic parts is shown in Fig. 2. Due to the large size of the plastic parts, the structure is complex, the parting surface is high and low, the wiping position is many, and the mold position is 1 out 1. The mold blank is the standard mold base CI3035 A70B110C90, the mold The design is shown in Figure 3. For this set of molds, the choice of mold opening direction is very important. Qualitative analysis shows that the clamping force of the plastic part on the front mold and the back mold is not much different. No matter which side of the plastic part is designed in the front mold, there is a risk of sticking the front mold. In the actual mold design drawing, the side with more bone positions was selected to be fixed. The advantage of this design is that the stroke of the slider is small. However, the position of the four holes in the middle of the plastic part makes it easier to stick the front mold. To this end, a core pulling method combining the rear mold slider and the front mold oblique elastic slider is designed. The front mold oblique slide slider can overcome the tightening phenomenon of the plastic part to the front mold while pulling the core. The front mold oblique slide block is limited by the limit block 21, see the section view M-M. The mold feeding method is the big nozzle mold, the gate is the side gate, and the glue is 3 points.
The design of the ejector system of the plastic parts is very critical. The plastic parts are symmetrical along the center line. Therefore, the ejector system design is also completely symmetrical. The ejection force at both ends is exactly the same. The ejector system is all ejector pins. The thimble hole is cut by a slow wire, and the diameter direction of the hole and the unilateral one side gap are 0.01, which can effectively ventilate without flaking. The method of detecting the thimble gap is to allow the thimble to be easily rotated without being stuck after being inserted from the rear mold. The thimble on the ejector plate has a depth tolerance of 0.02, which prevents the thimble from sticking and maintains the balance of the ejection force to prevent deformation of the injection mold plastic parts.