Two-color injection molding technology is also called double injection molding technology, which is a use of two plastic materials mixed plastic injection molding technology, its technical content is actually the use of a mold assembly for the shape of the mold in the mold Work of welding, so the fundamental principle is to plasticize the two different plastic materials, and then use the mold welding installation, in order to achieve the purpose of two-color injection molding.
1, two-color injection molding technology type
1.1 core rotating two-color injection molding technology
This technology is also known as the mold core color injection molding technology, the technical principle is the first use of injection equipment will be the first injection of plastic raw materials, the injection of small holes into the mold until it becomes the first plastic molding , And then the mold rotated 180 °, using the same injection equipment will be the second injection of raw plastic until the second plastic molding, the final encapsulation work, a basic two-color injection work is completed.
This technique is simple to use and operate, and generally less trained workers are free to operate and can greatly enhance the freedom of design of plastic products while being able to process with simple tools.
1.2 shrink core mold injection molding technology
Contraction mold Core-type two-color injection molding technology mainly uses the hydraulic device, the mold compression operation.First, under the control of the hydraulic device, will be able to move up and down the core as the piston is generally pushed up to the top position, and the plastic When the first raw material is solidified, the active core falls down and another plastic material is injected. Then, the hydraulic device is controlled to increase and suppress the core to be solidified and shaped.
This kind of technology suppresses the plastic product to the preliminary manufacture to complete, after then will form the plastic piece to take out, carries on the subsequent processing manufacture.This kind of technology operation is also relatively simple, must control the hydraulic equipment movement opportunity.
1.3 off board rotating two-color injection technology principle
This technology before work, we must first the first injection of raw materials in the injection, the other parts of the mold clamping process, the injection mold will be gradually cut and separated, the latter part of the insert will gradually Back, but still exist in the part of the off board, and the mold back to the dynamic path of the entire injection molding machine plunger and pull the grain of the rod after cooling and shedding, the first part of the completion;
The next part of the injection molding operation, in general and the first part is the same, but the second injection using two nozzles at the same time, waiting for the curing of the two parts together, to complete an injection cycle.
1.4 core sliding two-color injection technology
Core sliding type two-color injection technology works is the core is classified into two uses, the first injection will use the core slide to the specified location, the mold injection molding work, the first raw material Plastic injection mold, the mold after cooling once opened.
The actuator will slide the first core, the second core slide to the cavity site, and then a second injection of plastic until it is cooled forming, to complete an injection cycle, and then two synthetic Of the finished sliding top.This technology model is more suitable for large two-color injection plastic parts needs.
2, two-color injection molding process characteristics introduced
2.1 two-color injection molding machine structure of two sets
Two-color injection molding machines due to the impact of their production goals require two identical plastic injection molding machines, not only for their process but also for their ability to perform rotational transformations.
Both sets of the same specifications of the injection device in addition to the structure of the same need to have the same function, the injection molding can be two sets of equipment in the raw material temperature, injection pressure and injection rate consistent adjustment, making the injection of plastic products Of the indicators remain at a consistent level, and then the relevant integration and welding work.If the two sets of equipment parameters are inconsistent, we should try to adjust to a consistent level.
2.2 Two-color injection molding components and ordinary injection molding machine structure differences
Due to the unique characteristics of the plastic products produced by the two-color injection molding assembly, there are some notable differences between the mechanical settings of the machine and those of a conventional injection molding machine.
First of all, two-color injection molding components melt temperature higher, compared to ordinary injection molding components have a certain gap, the need for high temperature in order to maintain the ability to operate in the mold flow; followed by injection pressure is greater, not only because of the use of Are two different kinds of plastic raw materials, which need to be pressed and pressed to be fused, and moreover, it is designed to overcome the great resistance of the melt flowing in the mold to ensure the smooth operation of the injection molding.
2.3 two-color injection molding technology parameters of the material settings
Two-color injection molding technology uses two different materials for the production of plastic products, so injection molding before the need for material considerations, not only to consider the quality standards of selected materials, but also pay attention to the material in the injection molding temperature, pressure and other parameters control.
Because the two-color injection molding technology used in the mold and ordinary injection molding mold is different, which requires two-color injection molding technology materials used to have a higher melting temperature of the material to ensure that the melt is not cured before injection is completed, At the same time also use the injection device to control the pressure of the raw materials, so that it can successfully reach all parts of the mold, so as to achieve the purpose of injection molding.
3, two-color injection molding products and mold design points
3.1 Two-color injection molding structure of the product characteristics
The structure of two-color injection products is very different from the structure of common plastic products. Since two different materials are used for injection molding, the products have two different characteristics, which are fundamentally different from ordinary injection products. At the same time, Need to carry out the detailed two-color plastic injection molding structure design before injection, should take full account of the compatibility of the two materials.
Combined with the plastic products facing the function and use of the environment to design the mixing ratio of two materials and connections, a detailed analysis of the complexity of the process, but also to consider the use of strength design, so that two-color injection molding products to achieve the relevant material standards And request.
3.1.1 The choice of two materials
Two-color injection molding technology uses two different materials for injection molding, so the choice of two different materials is also an important process, the general choice of two different colors of plastic, which can greatly enhance the strength and durability of injection molded products, While making it easier to blend in. However, products of special use may need to exploit the extreme variability in the properties of the two materials, which necessitates the solution to the problem of the difficulty of achieving a high degree of integration between the two materials.
Mainly there will be stratification and shedding problems, which is a fatal blow to the injection molding, so the shrinkage and the interface of different conditions, the need for careful consideration, but also to adjust the proportion of the use of materials.
3.1.2 Product internal structure and shape design
The design of the product structure and shape first needs to be considered from the purpose and purpose of use of the product, and detailed study on the size and internal structure.
The general is to increase the contact area of the two raw materials to enhance the firmness in which products can be designed in the interior of some small grooves and grooves for mosaic and stitching, which reached the purpose of increasing the contact area of the two materials , In the injection molding will be able to better improve product use strength and service life, enhance the practicability.
3.2 rotating mold two-speed injection mold
This kind of mold needs different considerations in the forming part. Firstly, the concave and convex grooves of the two injection molds need to be strictly designed so as to ensure the perfect match in the docking. At the same time, the mold release mechanism needs to be re-injected to perform the mold release work, For different injection molding methods also need to make a detailed distinction between the vertical rotary injection molding machine to eject the finished product after the completion of the relevant operations, and can not use the injection molding machine ejection ejection need to use the hydraulic device off mold.
4 Conclusion
In summary, two-color injection molding technology after years of development, but in recent years it has gradually been valued and applied because of its finished products to the use of the environment has a very good adaptability, while the production efficiency is very high, Different practical requirements can be met well, so it is widely used gradually and has good economic benefits in the automobile industry and other fields. It is a technology with great potential for development.