Automotive Headlight Plastic Injection Mold, precision tool
Automotive Headlight Plastic Injection Mold
The car headlight reflector (also known as the mirror) is a part of the car headlight illumination system that reflects the function to avoid direct light. It is located inside the lens and the decorative frame, and is assembled with the lens. The lens can be seen from the outside of the lamp. Reflector. The plastic parts are appearance parts, the surface is plated with aluminum, which belongs to high-gloss plated parts, and the outer surface has a large area pattern for surface decoration. The lamp is an important safety device and decorative part essential for the car. The mirror has a shrinkage rate of almost zero due to the high temperature working environment and the reflection concentrating effect, and it has heat resistance, flame retardancy and strong resistance. Creep precast integral molding compound (BMC) thermoset plastic mould. This material has been used in the die-casting process. Due to the low production efficiency and high scrap rate, and because the material is harmful to the human body, it is necessary to manually pick up and weigh the material in the die-casting production process, thus bringing certain health to the operator. Danger. For this reason, it has become an inevitable trend to develop an injection molding process for BMC materials instead of a die-casting process.
1. Plastic parts appearance requirements and structural analysis
Automotive headlight reflector parts, made of BMC, are thermoset plastics. The material is a very hard material with a shrinkage rate of almost zero and no shrinkage is required during mold design. Because it is a special hard plastic, it has the advantages of high dimensional accuracy and good processing performance, and the disadvantage is that the fluidity is poor. The outer surface of the plastic part needs to be electroplated (usually aluminum-plated), and the plastic parts are appearance parts with high surface requirements.
2. BMC material injection moluding process
The refrigerated BMC material is added to the injection molding machine barrel specializing in the production of BMC material, and the shear heat is generated by the screw rotation to melt at a lower temperature (25 degrees Celsius), and then the thick gel-like material is injected into the preheating under high pressure. 140-160 degrees Celsius in the mold. Under the action of high temperature, the chemical reaction is carried out, and after solidification, it is solidified and molded, and the molded part is taken out by mold opening. Finally, the burrs and fragments in the cavity are blown off with an air gun, and the mold is closed for the next cycle.
3. Mold structure analysis
The headlight reflector of the car is a mirror image of left and right, and the number of cavities is 1+1. The mold adopts a cold runner casting system. There is no reverse buckle on the inner and outer sides of the plastic part, so there is no lateral core pulling mechanism. The mold dimensions are: 700 × 500 × 568 (mm), the total weight of about 1 ton, is a medium-sized injection mold.
4. Mold work process
The melt passes through the nozzle of the injection molding machine, enters the mold cavity through the nozzle 12, and after the melt fills the cavity, after being pressed, cooled and solidified, after being sufficiently rigid, the injection molding machine pulls the movable mold fixing plate 10 of the mold, and the mold is divided into points. The mold is opened at the profile PLI. After the mold is opened 300mm, the injection molding machine cylinder pushes the pusher fixing plate 8, and the pusher fixing plate pushes the push rod 28, and then the injection molding machine cylinder continues to function. After the 70mm is ejected, the plastic part is separated from the movable mold, and the plastic parts are taken by the robot. The injection molding machine cylinder pulls the pusher and its fixed plate to be reset, and then the injection molding machine pushes the movable mold to close the mold, and the mold starts the next injection molding.
5. Mold strength and parting surface tube design
The design of the mold surface of the mold is designed on the fixed mold, and the design of the four-corner joint and the four-sided rim is adopted, so that the positioning is reliable and the mold strength is good. In the design of the automobile mold, the angle of the insertion of the fixed mold is designed to be more than 7 degrees, and it is not necessary to design it at 5 degrees or more. Because the insertion angle is large, the life of the mold will be greatly improved, and the phenomenon of the trowel at the insertion of the mold will be greatly reduced. For the insertion angle of 3 degrees or less, 1 degree fine positioning and 0 degree fine positioning are difficult to ensure accurate positioning of the fixed mold, so the insertion angle should be as large as possible. For large and medium molds, the design is generally above 7 degrees. Thereby ensuring the service life of the mold.
6. Die exhaust system and discharge design
Ordinary thermoplastic molding is a physical change process, and thermosetting plastic injection molding is a chemical reaction process. When a chemical reaction occurs, a large amount of volatile gas is generated. These gases have great resistance to injection moulding, resulting in bubbles and defects on the surface of the plastic part. At the same time, the gas is compressed to produce a high temperature burnt plastic part. Therefore, the exhaust of the cavity of the thermosetting injection molding mold is particularly important. Generally, the mold parting surface and the bottom of the fixed mold insert need to be provided with a high temperature resistant sealing ring, and a vacuum is applied at the end of the fixed cavity of the mold cavity to overcome the molding defect. It is also convenient to increase the injection speed. The mold of the mold utilizes an insert, and the insertion of the needle and the movable mold is exhausted. BMC has poor fluidity, and it is necessary to design an overflow tank around the movable model cavity. The ejector pin needs to be designed at the bottom of the overflow tank to facilitate the ejection of the material.
Automotive Headlight Plastic Injection Mold
Plastic Injection Mold Show
Plastic Part Show
Please visit our website to learn more about Automotive Headlight Plastic Injection Mold.