Ear thermometer upper shell product is shown in Figure 1. Maximum dimensions of product are 147.63 mm * 30.05 mm * 27.75 mm; average thickness of plastic part is 2.00 mm, material of plastic part is ABS, shrinkage rate is 1.005, and weight of plastic part is 11.03 grams. Technical requirements for plastic parts are that there should be no defects such as peaking, Injection molding not fully filled, flow lines, pores, warping deformation, silver streaks, cold material, and jetting lines, and meet ROSH environmental protection requirements.

 

Figure 1 Product picture of upper shell of ear thermometer
Ear thermometers are medical devices for rapid body temperature measurement and have been widely used in recent years. Ear thermometers are also called ear thermometers. They have various structures and shapes, but generally speaking, they are shaped as curved and slender strips. Ear thermometers generally include two parts, an upper shell and a lower shell, which are assembled into a complete body. case. There is a circular hole in head, which is assembled with sensing head, window in the middle of shell is display screen, and tail is buzzer. Edges of upper and lower shells are buckles for assembly, and generally require sliders or lifters to solve problem of demoulding.

 

Figure 2 Die structure diagram (sketch)
Plastic part of upper shell of ear thermometer is relatively small, but structure is complex. Buckles on the side edges need to be designed with sliders or sloped tops for demoulding. For curved head and round hole, it is necessary to design an inclined slider for front and rear molds to penetrate. Slider structure shown in Figure 3 and Figure 4.

 

Figure 3 Die parting surface diagram

 

Figure 4 Slider structure diagram
Front mold inclined slider is driven by T-slot, and rear mold inclined slide is also driven by T-slot. Design of T-slot driving slider is mostly used for core pulling of fixed mold slider and moving mold slider with small spatial position; it can also be used for core pulling of inclined large slider. When width of slider is large, it is difficult to balance movement of slider with one inclined guide post, and it is difficult to achieve consistency with more than two inclined guide posts. At this time, it is the best choice to use T-slot to drive slider. T-slot parts are generally processed by wire cutting.
Front mold is designed with T-shaped groove sliders, and each template can be opened, which is beneficial to relative movement of shovel and front mold sliders. In order to realize core-pulling of slider, rear mold needs to be lifted up so that slider and shovel can achieve core-pulling through relative movement. Lifting stroke of rear mold plate needs to be driven by a buckle.

T-groove sliders are often used in occasions where space is small, and can also be used for moving mold sliders instead of inclined guide posts. T-slots are often processed by wire cutting, which requires high processing accuracy. Slope tolerance is usually ±0.05゜, and rest of dimensional tolerances are shown in Figure 5.

 

Figure 5 General tolerance design requirements for T-slot sliders
Slide block in Fig. 5 is wider, and two T-shaped grooves are designed to drive slide block. Cooperation between T-slot of T-slot slider and shovel requires wire cutting, and its machining accuracy needs to follow tolerance shown in Figure 5. When assembling, two moving parts can be slip-fitted.
Molds for upper shell and lower shell of ear thermometer generally have a mold position of 1 cavity, or 2 cavities. Size of plastic part is not large, but structure is complex, especially elbow part, which generally needs to be designed with an inclined slider to pull core. Buckles for assembly of upper and lower shells also need to design slider core pulls. Therefore, design cavity arrangement of mold is 1 cavity. Mold base is a standard fine runner mold base DCI2535, gate is a point gate, glue is injected at one point, and it is selected at sinking part of upper surface of elbow. After gate is broken, position of gate should not be raised, so as not to affect assembly of plastic parts.
Ejection of mold adopts inclined ejector, cylinder and thimble ejector. Design of lifter at elbow part is mainly to avoid interference between slider and T-slot slider of rear mold. Cooling system of mold adopts straight-through water transportation. For small molds, direct-through water transportation has a simple structure and is not easy to be blocked. It is the most common cooling method.