Automotive parts injection mold design
Injection molds are mainly used for the molding of thermoplastic products. In recent years, they have also been used more and more for the molding of thermosetting plastic products. Injection molding has a large proportion in the molding of plastic products. More than half of the world's plastic molding molds are injection molds.
Plastic classification: There are many varieties of plastics, which can be divided into thermoplastics and thermosetting plastics according to processing properties. Thermoplastic refers to plastic that can be repeatedly heated and cooled in a specific temperature range. After heating the thermoset to a certain temperature, it is no longer fusible and plastic.
Typical Injection Mold Design Process In the Pro/ENGINEER environment, the injection mold design process consists of the following steps:
(1) Create a plastic part model (also known as three-dimensional modeling);
(2) Create a blank to define the volume of all mold components;
(3) Build the characteristics and dimensions of the cavity and core according to different shrinkage rates, draft angles and plastic parts models;
(4) adding mold assembly features to form a gating system, defining a parting surface and a module;
(5) defining the steps of opening the mold and checking the interference;
(6) Assembling the mold base as needed to complete the cooling system design;
(7) Complete the parts drawing of all parts;
(8) Generate the NC code of the part according to the processing needs.
Let's take a atumotive parts of the car as an example to introduce the design process.
Create a plastic part model (also known as three-dimensional modeling);
Among them, you should pay attention to the following matters when building a 3D part drawing.
1) The wall thickness of the part should be determined reasonably
1. Under the premise of meeting the requirements of use, minimize the wall thickness;
2. The wall thickness of each part of the part is as uniform as possible to reduce internal stress and deformation;
3. The compression strength must be ensured in the part that bears the fastening force;(example automotive parts)
4. Avoid shrinkage holes and depressions in thick parts;
5. It can withstand the impact of impact when the molding is ejected.
2) The necessary draft angle must be set
1. For plastic parts with large shrinkage rate, a large draft angle should be selected;
2. For large-size parts or parts with high dimensional accuracy requirements, a small drafting angle should be used;
3. When the wall thickness of the workpiece is thick, the molding shrinkage is increased, so the draft angle should be large;
4. For the reinforced plastic, the draft angle should be large;
5. Easy release plastics such as self-lubricating agents can be taken small;
6. In general, the draft is not included in the tolerance of the part.
3) The corners are designed to be rounded as much as possible(example: automotive parts)
Rounded corners avoid stress concentration and increase the strength of the part;
Rounded corners can facilitate filling and demolding;
Rounded corners are good for mold making and increase mold strength.