1. The definition of injection mold
The injection mold can form plastic products with complex shapes, high dimensional accuracy or with inserts at one time.
"Seven points mold, three points technology." For the injection molding process, the mold has a great impact on the quality of the molded product like the injection molding machine. It can even be said that the mold plays a greater role than the injection molding machine; if you do not fully understand the mold during forming, it is difficult to obtain excellent molded product.
2, The structure of the injection mold
The structure of the injection mold is determined by the type of injection molding machine and the structural characteristics of the plastic part. Each mold is composed of a movable mold and a fixed mold. The movable mold is installed on the movable plate of the injection molding machine, and the fixed mold is installed on the fixed plate of the injection molding machine; during injection, the movable mold and the fixed mold are closed to form a pouring system and cavity. When the mold is separated, the plastic part remains on one side of the movable mold, the plastic part is ejected by the demoulding mechanism set in the movable mold. According to the different roles of various parts in the mold, a set of injection molds can be divided into the following parts:
1). Molding parts
The parts that give the shape, structure, and size of the molding material are usually composed of cores (punch molds), concave mold cavities, threaded cores, inserts, etc.
2). Pouring system
It is the channel that leads the molten plastic from the nozzle of the injection machine to the closed mold cavity. It usually consists of a main channel, a shunt channel, a gate and a cold well.
3). Guiding parts
In order to ensure that the movable mold and the fixed mold can be accurately aligned when they are closed, the guide parts play a guiding and positioning role. It is composed of a guide post and a guide sleeve. Some molds are also equipped with guide parts on the ejector plate. Ensure that the demoulding mechanism moves smoothly and reliably.
4). Demoulding mechanism
The device that realizes the demolding of plastic parts and the pouring system has many structural forms. The most commonly used are ejector pins, ejector pipes, top plates and pneumatic ejector ejection mechanisms, which are generally composed of ejector rods, reset rods, springs, ejector fixed plates, top plate(top ring) and EGP/guide sleeve of top plate (top ring) and top plate guide post/guide sleeve.
5). Mold temperature adjustment system
In order to meet the mold temperature requirements of the injection molding process, a mold temperature adjustment system is required to adjust the mold temperature.
6). Exhaust system
In order to smoothly exhaust the gas in the mold cavity, an exhaust groove is often set at the parting surface of the mold and the matching part of the insert.
7). Other structural parts
Refers to the parts (such as: fixed plate, movable/fixed template, support column, support plate and connecting screw, etc.) set to meet the requirements of mold structure.
3. Composition and function of injection mold
1). Upper fixing plate: It is an indispensable part for the mold opening and closing of the machine table to fix the mold and the front mold part of the mold.
2). Stripping plate: fixed drawing nozzle plate.
3). Magnet: The opening and closing of the mold is controlled by magnetism. Or use deduction mechanism.
4). Male template: fixed male mold core and mold core bearing plate.
5). Template bearing plate: Fix the male template and install the heating rod at the same time.
6). Material guide pin: fixed material belt.
7). Limit column: limit the ejection height of the guide pin.
8). Mould angle: fixed function, while giving the thimble board enough height movement stroke
9). Upper thimble plate: fixed thimble.
10). Lower thimble plate: Fix the upper thimble plate.
11). Lower fixed plate: Fix the mold feet and trash nails. At the same time, it provides a foundation for the lower mold and is used to open and close the mold on the machine table to fix the mold.
12). Garbage nails: limit the height, so that the lower thimble plate and the lower fixed plate cooperate smoothly, prevent miscellaneous materials from entering between the two plates, and make the thimble and guide pins eject unevenly.
13). Top stick column (K.O column): used for ejecting the thimble and guide pin of the machine.
14). Small thimble plate: fixed guide pin.
15). Small thimble plate: fixed guide pin.
16). Thimble: eject the product to separate the product from the mold.
17). Outer tie rod: used to open the cavities and limit the mold opening distance of the cavities.
18). Heating rod: heat up the mold. Or use a water transportation agency.
19). Mold core bearing plate: fixed back mold core and back mold inserts.
20). Male mold core: fixed insert pin insert sleeve, mainly used for product molding.
21). Runner: part of injection molding.
22). Female mold core: fixed front mold insert, mainly used for product molding.
23). Master template: fixed master core.
24). Small tie rod: fix the mold opening stroke of the upper fixed plate and the stripper plate.
25). Die core backing plate: Fix the mother core and press and insert the heating rod at the same time.
26). Pulling fixing plate: Fix the pulling needle to prevent the mold from ejecting the pulling needle during the injection molding process.
27). Mouth: the main entrance for injection molding of the nozzle of the machine.
28). Pulling plate: Pull up the pulling needle.
29). Material-pulling nozzle plate: fixed material-pulling needle.
30). Front mold insert: fixed runner plate and female mold core.
31). Rear mold inserting needle inserting sleeve: mainly used for forming the cup mouth of the product.
32). Pulling needle: Pull the nozzle.
4, the structural classification of injection molds
1). Classified by molding method:
(1) Injection mold: the mold used on the injection machine. It is mainly used for molding thermoplastics, and a few varieties of thermosetting plastics are suitable for the molding of this mold.
(2) Compression mold: It is a mold that uses compression technology to form plastic parts on a hydraulic press. It is mainly used for molding thermoset plastics.
(3) Pressure injection mould: It is a mould that uses pressure injection technology to form plastic parts on a hydraulic press. It is suitable for molding thermoset plastics.
2). Classified by the number of cavities:
(1) Single cavity mold
It is a mold with only one cavity, and one plastic part is formed at a time.
(2) Multi-cavity mold
It is a mold with two or more cavities, which can form multiple plastic parts in one mold.