Car armrest box is a kind of car accessory installed between two seats, which belongs to car interior system. Original intention of its humanized design is to enable car driver to place his arm during long-term driving, so that arm can be effectively rested without numbness and stiffness. With continuous development of manufacturing technology and continuous improvement of production technology, armrest box has more storage functions, such as storing small objects such as beverages and water cups, so that driver can easily get these small objects when necessary. Product picture of central armrest box storage box is shown in Figure 1. Maximum size of plastic part is 338.84.67mm*147.67mm*199.39mm, average wall thickness is 2.32mm, and weight of plastic part is 292 grams. Material is FPP TSOP-AT5HF. Shrinkage rate is 0.0095, plastic part itself must not have weld marks, bubbles, burrs and other injection defects.

 

Figure 1 Product Picture of Central Armrest Box Storage Box

 

Plastic part of central armrest box storage box is an automobile part of Canada GTS company. This article mainly introduces GTS automobile mold design standard and related design essentials based on plastic part.
Structure of plastic part is complex, shape is irregular, and parting surface has large fluctuations. There are multiple buckles on the edge of plastic part, it is necessary to design slider and lifter to solve demolding problem. There is a closed box sinking position in the middle of plastic part, front mold has a large protrusion height, amount of material removed during mold processing is large. It is necessary to select a tool with a larger diameter for rough processing. Choice of tool path during finishing is also critical. It is directly related to accuracy and processing efficiency of parting surface.
Size of plastic part is larger and depth is deeper. Mold design cavity rank is 1 cavity. Mold base is an inch size mold base, and its maximum external size is 23"x 27"; In horizontal alignment diagram of front and rear molds of mold design, dimensions of four green columns of injection molding machine are drawn, dimensions of injection molding machine are listed on green columns of reference angle. Specifications of injection molding machine include: tonnage: 250 tons; Green column spacing: 27.5"; mold fixed plate size; 27"x 27"; maximum mold thickness 26", minimum mold thickness 10.65", maximum opening distance of injection molding machine 42"; maximum ejection stroke is 6". Front and rear mold plans need to be marked with operating side, non-operating side, sky side and ground side.
Due to complex structure of mold, side view of mold requires multiple cross-sectional views to completely and clearly express complete mold structure. For example, sections B, D, F, H, J, K, M, L, G, E, A, C, etc., are used to express the overall structure of mold completely and accurately. These structures include sliders, gates, different lifters, ejection systems and guide systems. Projection direction Y and Z of projection view are at base angle, views are VIEW "Y" and VIEW "Z" respectively. See mold design drawing 2.

 

Size of plastic part is larger in height direction, movable and fixed molds are all left on mold base. In order to improve positioning accuracy, 10mm precision positioning is designed in four guide posts and guide sleeves.
Gating system of mold adopts hot runner forming. System includes a splitter plate and two hot nozzles to feed glue at both ends of plastic part. After molten plastic flows out of hot nozzle, it enters inner part of plastic part through horn gate. After mold is opened, gate can be automatically cut without affecting appearance of plastic part. In order to ensure rigidity of front mold, four positioning pins with a diameter of 1" are designed between three mold plates of front mold.
Slide core pulling system of mold is driven by an oblique guide post. Inclined surface and bottom of slider are all designed with wear-resistant plates. Positioning of slider adopts DME standard tiger buckle positioning. Considering large thickness of A plate, installation method of inclined guide post is pressing method of pressing plate. Drill holes in corresponding position of each template for use when removing oblique guide post. Fixing method of oblique guide post of large mold is shown in Figure 5.
Considering large size of lifter, a round guide column is used as lifter rod to guide lifter ejection. Note that guiding angle is different from angle between lifter and mold core to facilitate lifter ejection. Fixing screws of inclined ejector rod also drill holes in thimble plate and bottom plate to avoid gaps to facilitate mold maintenance.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2 Mould diagram of storage box of central armrest box

 

Figure 3 3D mold diagram

 

Figure 4 Injection molding machine specifications on green column

 

Figure 5 Fixing method of oblique guide post of large mold