Injection Mold. Composition and Classification

Composition and classification of injection mold

The structure of the injection mould is determined by the complexity of the plastic parts and the structure of the injection machine. The fixed mold part is installed on the fixed template of the injection machine, and the moving mold part is installed on the moving template of the injection machine. In the process of injection molding, the moving mold part moves with the mold matching system of the injection machine, and the moving mold part and the fixing mold part are guided and closed by guide column to form the pouring system and mold cavity. The plastic melt enters the mold cavity through the pouring system from the nozzle of the injection machine. After cooling, when the mold is opened, the moving mold part and the fixing mold part are separated to take out the plastic parts.

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According to the role of each part of the mold, the injection mold is composed of molding parts, structural parts, pouring system, temperature regulation system and exhaust system.

1. Molding parts

The parts that make up the cavity. Such as: punch (core), die and inserts and inserts, etc. The punch (core) forms the shape of the inner surface of the plastic part, and the die (cavity) forms the shape of the outer surface of the plastic part. When the die is closed, the punch and die form the cavity of the die. In the mold, the cavity is composed of moving template 1, fixed template 2, punch 7, etc.

2. Structural parts

A die frame, mechanism, etc. Die frame such as: upper, lower die seat, supporting parts, etc. Mechanism, such as: mold closing guide mechanism, push mechanism, side core-pulling mechanism, etc.

Supporting parts are used to prevent forming parts and parts of the mechanism under the action of forming pressure deformation phenomenon of the supporting parts. Mold support parts mainly include: support block (pad), support plate (dynamic die pad), support block, support plate, support column (dynamic die pillar) and so on. Die - closing guiding mechanism is to ensure that the moving die and fixed die in the die - closing accurate alignment. Commonly used are: guide pillar guide mechanism and cone guide mechanism. The push mechanism refers to the device that pushes the plastic part from the mould after parting. Common are: push rod out, push tube out, push plate out, die out, out of sequence and other institutions. Lateral parting and core-pulling mechanism is a device that disengages or pulls the concave and convex shaped module or core from the plastic part before opening the mold when the side wall of the plastic part has concave and convex shape.

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3. Casting system

The channel through which molten plastic enters the mold cavity from the nozzle of the injection machine is called the pouring system. The pouring system consists of four parts, such as the main flow channel, the shunt channel, the gate and the cold material hole.

4. Temperature control system

In order to meet the temperature requirements of injection process, the temperature of the mold must be controlled. The cooling system generally provides cooling channels on the mold (FIG. 4-1, FIG. 3), while the heating system installs heating elements inside or around the mold.

5. Exhaust system

In the process of injection molding, an exhaust system is often needed to remove the air from the mold cavity. The exhaust system is usually purposefully provided with several exhaust grooves on the parting surface. In addition, the matching gap between the push rod of many molds or the movable core and the template can also play the role of exhaust. Small plastic parts of the exhaust volume is not large, so can directly use the parting surface exhaust.

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Structure of injection mould

1- moving template; 2- fixed template; 3- cooling channel; 4- die setting base plate; 5- positioning ring; 6- gate cover; 7 - punch; 8 - guide pillar; 9 - guide bush; 10- movable die seat plate; 11- support plate; 12- supporting column; 13 - push board; 14- push rod fixing plate; 15- pull rod; 16- push plate guide post; 17- guide sleeve for push plate; 18 to push rod; 19- reset lever; 20 - block; 21- injection machine ejector rod

Classification of injection molds

Plastic injection molding mold is mainly used for thermoplastic molding. There are many classification methods for injection molds, which are summarized as follows:

(1) according to the type of injection machine used for injection mould, it can be divided into horizontal injection machine mould, vertical injection machine mould and angular injection machine mould;

(2) according to the properties of plastics, it can be divided into thermoplastic injection molds and thermosetting plastic injection molds;

(3) according to the structure of the pouring system, it can be divided into ordinary runner injection mold and hot runner injection mold;

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(4) according to the number of cavities, it can be divided into single-cavity injection molds and multi-cavity injection molds;

(5) according to the injection molding technology can be divided into low foam injection mold, precision injection mold, gas-assisted injection molding injection mold, monochrome injection mold and multi-color injection mold;

(6) according to the characteristic of typical of injection mold structure can be divided into single parting surface injection mould, double injection mold parting surface, inclined guide pillar (bent pin, oblique guide groove and technoloy, gear and rack) side parting and core-pulling injection mould, injection mould, with activities set piece fixed mold of the injection mould and automatic discharge on a thread injection mould, etc.

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