Key points for the design of the inclined ejector of the injection mold
Inclined top is a common ejection element, which has two functions: ejecting the undercut and ejecting the plastic part. When the inclined top is designed, it will often interfere with the side tube or insert, as shown in Figure 1. (A) The distance between the inclined roof and the main tube is very close, which will cause interference; at this time, it is necessary to lengthen the broken surface of the top of the inclined roof to keep the inclined roof away from the main tube, as shown in Figure (b). (C) The distance between the inclined top and the insert is very close, (d) the fixed plate is designed at the bottom of the insert to shorten the insert and solve the interference.
In different countries and different companies, there are some customary design methods for the stability of the inclined jack. In molds exported to developed countries such as Europe, America and Japan, customers will have certain requirements for inclined roof design. Generally speaking, customers require the inclined top to be designed directly on the thimble board. That is, the simple inclined roof structure shown in Figure 2 cannot be used. The advantage of the simple inclined top is that it can avoid the interference of the inclined top with the thimble or other components in some situations, and occupy less space on the thimble board. When the inclined ejector is ejected, the guide pin and guide sleeve is designed on the ejector plate, which can greatly increase the stability of the inclined ejector.
In the export mold, the conventional inclined roof design should connect the inclined roof to the push plate, and the simplified inclined roof can be used in special situations such as excessively long inclined roof, limited space, beyond the range of the ejector plate, and mutual interference. The use of simplified inclined tops in molds exported to Europe, America and Japan should be confirmed by customers.
Note when using simple inclined top: In the mold of fixed-molded inclined elastic slider, it is not suitable to use simple inclined top, so as to avoid interference between the inclined elastic slider and the inclined top, and the inclined top cannot be reset.
Extremely small inclined roof means that when the plastic part is relatively small, the size and stroke of the inclined roof are very small due to the limitation of the plastic part structure. At this time, the strength of the inclined roof is very weak, so shorten the length of the inclined roof as much as possible, and use reliable Inclined top guide mechanism and nitriding of inclined top parts. Figure 3 shows the structure of the extremely small inclined top of the mobile phone shell. The height of the inclined top seat 5 is increased, and the inclined top seat 5 is slidingly fitted in the guide block 4, and the length of the inclined top 2 is shortened. The inclined roof 2 and the inclined roof seat 5 are matched with an arc surface.
Another important problem of the inclined top ejection is the anti-loosening problem. If the screws of the inclined top connection are loose, the inclined top mechanism will fail, which will seriously affect the life of the mold. For the extremely small inclined top shown in Figure 3, a spring washer 9 is added under the screw to prevent loosening.
In order to increase the wear resistance of the small inclined roof, nitriding treatment is often done. The current new DLC technology can effectively extend the life of the small inclined roof. DLC is a substance composed of carbon, which is similar in nature to diamond, and at the same time has a structure composed of graphite atoms. Diamond-like carbon film (DLC) is an amorphous film. Due to its high hardness and high elastic modulus, low friction factor, wear resistance and good vacuum tribological properties, it is very suitable as a wear-resistant coating, DLC film Not only has excellent wear resistance, but also has a very low friction coefficient, generally lower than 0.2, which is an excellent surface anti-wear modified film. The friction coefficient of DLC varies with the preparation process and the composition of the film, and the friction coefficient can reach as low as 0.005. DLC technology increases the life of small inclined roofs by reducing frictional resistance.
ABIS MOLD TECHNOLOGY CO.,LTD
Daisy Wang (Sales Engineering)
M: +86-150 1652 6799
E: daisy@abismold.com
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