Some plastic self sealing bags get a blind hole after forming and then drill through. This method is suitable for thin and deep holes to prevent core deformation during forming. Plastic products have no holes after forming, and then the holes will be processed again. The latter two knife methods are limited to a few easy cutting materials, such as nylon. At the same time, because of secondary processing. The production efficiency is low, and it is difficult to guarantee the quality of fine holes, so it is rarely used. This section mainly introduces the design principle and processing method of the hole directly generated during forming.

對在成型時直接生成的孔，無論伺種類型，均應設置在不易削弱制品強度的部位，且孔的形狀應力求不使模具制造工藝復雜化。是在成型的制品殘留熔接痕和削弱強度的重要因素。周圍設一個凸邊來加強。同時，孔與孔的間距及幾到制品邊緣的距離也要適當。所示的尺寸關(guān)系確定，當兩個孔不一“樣大小時，按小7L取值；熱塑性塑料自封袋的注塑制品按表2—7中數(shù)值的75％取恒。不同類型的孔的深因成型方法的不同而不同。通孔注塑制品L的通扎用得很多，成型通孔用的型芯一般有以門L種安裝辦法。

For the holes directly generated during forming, regardless of the type, they should be set at the parts that are not easy to weaken the strength of the products, and the shape of the holes should strive not to complicate the mold manufacturing process. It is an important factor for residual weld lines and weakening strength of formed products. A convex edge is set around to strengthen. At the same time, the spacing between holes and the distance from several to the edge of the product should also be appropriate. According to the dimensional relationship shown in, when the two holes are different in size, the value shall be taken as 7L; the injection molded products of thermoplastic self sealing bags shall be taken as 75% of the value in table 2-7. The depth of different types of holes varies with different molding methods. The through-hole injection molded products L are used a lot, and the core for forming through-hole generally has l installation methods.

內(nèi)一端固定的型芯來成型，且易生成飛邊，當型芯較細時易彎曲。這種固定型芯的方法不能成型深孔。由兩個兩端固定的則芯來成型，由于將一個型芯設計得比另一個大o．5—1mm左右，保證孔的同心度，不于引起安裝和使用土的困難，而且增加了型芯的穩(wěn)定性，孔的精度低。由一端固定，一端導向支撐的型芯來成型，這樣型芯有較好的強度和剛度，又能保證同心度，但導向部分易因?qū)蛘`差磨損而產(chǎn)生圓弧溢料。以上無論采用何種固定方法，孔的深均不能太大，公則型芯會彎曲。通常九探隨塑料流動性的4(同而不同，流動性好的塑料自封袋的7L的深可以達到10倍孔徑，流動性中等的不能超過7倍孔徑，而流動性差的塑料制品的孔深小于4倍7L徑；否則只能采取機械加工的力法獲得。

The inner end is formed by a fixed core, and it is easy to generate flash. When the core is thin, it is easy to bend. This method of fixing the core cannot form deep holes. It is formed by two cores fixed at both ends. Because one core is designed to be about 0.5-1mm larger than the other, the concentricity of the hole is guaranteed, which will not cause difficulties in installation and use of soil, and increase the stability of the core, and the accuracy of the hole is low. It is formed by the core with one end fixed and one end guided and supported, so that the core has better strength and stiffness and can ensure concentricity, but the guide part is easy to produce arc overflow due to the wear of guide error. No matter what fixing method is adopted, the hole depth should not be too large, and the core will be bent. Generally, the depth of 7L of plastic self sealing bag with good fluidity can reach 10 times the aperture, and that of plastic products with medium fluidity can not exceed 7 times the aperture, while that of plastic products with poor fluidity is less than 4 times the 7L diameter; otherwise, it can only be obtained by mechanical processing.