The main body of the car front bumper injection mold uses the internal parting surface technology, through the hot runner, and by the sequence valve control into the glue. On both sides of the torque with large inclined top horizontal inclined top add straight on the top of the structure, the mould due to the direct roof and pitched roof is very big, inclined plunger and plunger straight by 50 to 60 mm, lateral oblique push rod by 25 to 35 mm, big inclined by the Angle of 16 degrees, for ejection Angle is greater than 12 degrees above, must design guide bar structure, so the mould large inclined top guide bar structure is designed. The maximum size of the mold is 2500×1560×1790mm, and the weight is about 30T. See Figure 22 for the mold structure. There are 7 side holes on the outside side of the front bumper, and the fixed die elastic needle structure is adopted in the mold. The design of the mold uses the advanced internal parting surface technology. The so-called internal parting technology is relative to the external parting, usually the general products are in accordance with the maximum projection contour of the product for the fixed die parting line, this is the external parting, the general mold is in accordance with this way of parting. Internal parting is to hide the parting clip on the non-appearance surface of the product (that is, side B or side C, the appearance surface is side A), and the parting clip cannot be seen after assembly on the vehicle, so as not to affect the appearance. In order to achieve this function, the mold structure through the track technology to control the transverse inclined top (or straight top) in the secondary rail operation, so as to ensure the deformation and demoulding of plastic parts, the use of this secondary rail technology controlled by the mechanism, called the internal parting technology. In the design of automobile injection mold, internal parting technology is specially designed for automobile bumper. However, this technology is more complex than the external parting bumper in difficulty and structure, and the technical risk is higher. The cost and price of the mold will be higher than that of the external parting bumper. However, because of its beautiful appearance, it is widely used in middle and high-end automobiles.
For auto bumper plastic parts, there are generally external parting and internal parting two ways. For all the large area of the upside down on both sides of the bumper, that is, the outside parting can be used or the inside parting can be used. The choice of these two parting methods mainly depends on the requirements of the final customer's car oems on the bumper. Generally, European and American cars mostly use the internal parting technology, while Japanese cars mostly use the external parting technology. The two kinds of parting methods have advantages and disadvantages. The outer parting bumper needs to deal with the clamping line, which increases the processing process, but the cost and technical difficulty of the outer parting bumper in the mold is lower than that of the inner parting bumper. Inside the parting of the bumper through the secondary rail control technology, a perfect one-time bumper injection out, so as to ensure the appearance of the bumper quality, save the plastic parts processing process and processing costs. But the disadvantage is that the mold cost is high, the mold technical requirements are high.
