Automobile door guards are an important part of automobile interior parts. In automobile interior parts, all parts related to door guards are collectively referred to as door guard assembly. Main function of door guards is to cover metal door panels, provide beautiful appearance, and meet ergonomics, comfort, functionality and convenience. Provide appropriate energy absorption protection in side collisions and shield noise outside car.
Automobile door panel mold
In automobile interior parts, door guards are parts that integrate safety, comfort, and decoration. Automobile door guards are generally divided into hard and soft types, are divided into integral and split types in terms of plastic part design. Hard door guards are usually made by injection molding. (If there are no special requirements for shape, color separation and materials, they can also be made into a whole with door guards).

 

Above picture shows a certain brand of automobile door panel parts, material is PP+EPDM, and door panel dimensions are: 641.4×274.6×75.4mm.

 

 

Automobile Door Panel Mold
This mold casting system adopts hot runner injection, and adopts 3-point sequential valve hot runner injection method.

 

Product appearance surface requirements: sunburn, appearance surface demoulding slope of at least 5 degrees, no gate mark, weld line, shrinkage and other injection defects.

Automobile Door Panel Product Mold Flow Analysis

 

Automobile Door Panel Mold
Door panel is an appearance part, and no weld marks are allowed on the surface. During injection molding, weld marks must be driven to non-appearance surface or eliminated. This is one of key points and difficulties of this mold design. Although traditional synchronous multi-point injection can fill the entire cavity with melt, it is difficult to achieve ideal product quality due to existence of weld marks. For this purpose, this mold adopts 3-point sequential valve hot runner gate control technology, which controls opening and closing of 3 hot nozzles through drive of oil cylinder, thereby achieving ideal effect of no welding marks on the surface of plastic part.

 

 

Automobile door panel mold
Four sides of front and rear molds are surrounded by 5° slopes, and wear-resistant blocks are made around them. This four-sided surrounding design method is widely used in automobile molds.

 

 

 

Automobile door panel mold

 

Mesh structure is core structure of automobile door panel injection mold. This mold has no sliding position and less inclined tops, which is relatively rare for door panel molds.
In structural design of lifter, inclination angle of lifter should not exceed 12°, and design of lifter should prevent product from sticking to lifter when demolding.

 

Automobile door panel mold

 

AB plate adopts square guide pin guide positioning. Mold base size can be made smaller, saving cost and making mold structure more compact.

 

Eight 1-degree precision positioning are designed near R corner of four corners of mold, which is equivalent to edge lock of mold base. Principle is same, but design style has changed. This is difference of large mold.

 

Automobile door panel mold
Mold ejection adopts 4 oil cylinders, and mold adopts straight ejection + ejector pin + lifter + sleeve + secondary ejection.

 

 

 

Automobile door panel mold
Automobile door panel is one of the most important interior parts of car, and it is also one of plastic parts with high appearance requirements. Therefore, quality of temperature control system design has a great influence on molding cycle and product molding quality of mold. One of design principles of cooling water channels is that distance from cavity surface should be roughly equal to achieve roughly balanced temperature at all locations in mold cavity. Temperature control system of this mold adopts a combination of "straight-through water pipe + water well + inclined water transport".

 

 

Front and rear molds of this mold are designed with mesh inserts, and a set of cooling water cooling is designed separately for mesh inserts. In order to avoid air entrapment, mesh inserts need to be made of breathable steel materials. Breathable steel materials are generally very expensive. If S136 steel is used, exhaust pins or inserts need to be designed on mesh inserts, and exhaust grooves need to be designed at the bottom of mesh inserts to facilitate gas discharge.

 

 

Summary

 

In design of automobile mold temperature control systems, there are mainly two combinations:
(1) The first combination: straight-through water pipe + inclined water pipe + water well;
(2) The second combination: straight-through water pipe + water well + inclined water pipe.
Difference between these two forms is that between inclined water pipes and water wells, the former gives priority to inclined water pipes, while the latter gives priority to water wells. These two combinations have different focuses, so effects are also different.
Advantage of the first form is that cavity is cooled evenly everywhere, forming cycle is short, and quality of plastic parts is high. It is suitable for molds with high requirements and high appearance performance requirements, such as front and rear bumpers of automobiles, upper and lower dashboard bodies of automobiles, left and right door panels of automobiles. Disadvantage is that processing cost is high, it is mainly suitable for molds of European and American customers.
Advantage of second form is that processing cost is low and processing is convenient and fast. Disadvantage is that too many wells designed on mold have a certain impact on strength of mold. Cooling effect of cavity is worse than the first one. It is more used in automobile molds produced in Japan and China. This mold is to reduce processing cost, so second combination form is adopted.
For automobile plastic parts, cooling water channel designed naturally with shape is good for cooling of plastic parts and life of mold. Strict European and American molds do not even allow or try to use cooling wells and sealing rings as little as possible. Because diameter of well is large, too many wells will affect strength of mold and shorten life of mold. Seal ring is prone to aging and failure, so its use must be minimized in design.

 

Since this mold has mesh holes, mesh holes seriously affect computer running speed during design. This section focuses on mesh design method and design experience and skills of door panel mold.

 

For mesh design, it is not necessary to design every mesh hole on 3D. You only need to design a small number of reference mesh holes, then design mesh distribution lines of different colors on parts, and use 2D lines to represent distribution of mesh holes, as shown in figure above.

 

Design method for equal height of mesh holes that penetrate and design method for equal height of mesh holes that do not penetrate
1. Take height of mesh holes that penetrate as benchmark, seal long steel material, and cut out several mesh holes locally as benchmark for mesh size for design.
2. If mesh holes that are hit or not hit are not of same height, then we need to perform 3D real modeling on all mesh holes of different heights;
3. This design method is only for circular mesh holes, and mesh holes of other shapes need 3D real modeling.