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Brief introduction of injection molding technology and equip

Injection molding machine (injection machine or injection molding machine for short) is to make thermoplastic or thermosetting materials by plastic molding mold
 
The main molding equipment for plastic products of various shapes.
 
Injection molding is realized by injection molding machine and mold.
 
2、 Type of injection molding machine
 
The types of injection molding machines are vertical, horizontal and all electric, but no matter what kind of injection molding machine, its basic functions are two
 
Number:
 
(1) Heat the plastic to a melting state;
 
(2) A high pressure is applied to the molten plastic so that it is ejected and filled into the mold cavity.
 
3、 Structure and function of injection molding machine:
 
Injection molding machine usually consists of injection system, mold closing system, hydraulic conveying system, electrical control system, lubrication system
 
Heating and cooling system, safety monitoring system, etc.
 
(1) Injection system
 
Function of the injection system: the injection system is one of the most important parts of the injection molding machine, generally including plunger type and screw type
 
There are three main forms: rod type and screw type. At present, the most widely used is screw type. Its role is to,
 
In one cycle of the injection molding machine, a certain amount of plastic can be heated and plasticized within a specified time, and then
 
The molten plastic is injected into the mold cavity through the screw under the pressure and speed of. At the end of the injection, the injection to the mold cavity
 
The melt in remains set.
 
Composition of injection system: the injection system is composed of plasticizing device and power transmission device.
 
The plasticizing device of screw injection molding machine is mainly composed of feeding device, barrel, screw and nozzle. Power transmission
 
The device comprises an injection cylinder, an injection base moving cylinder and a screw driving device (glue melting motor).
 
(2) Clamping system
 
Function of die closing system: the function of the die closing system is to ensure that the die is closed, opened and ejected. At the same time, in
 
After the mold is closed, sufficient mold locking force is applied to the mold to resist the mold cavity pressure generated by the molten plastic entering the mold cavity,
 
Prevent the mold from seaming, resulting in the poor status of products.
 
Composition of the die closing system: the die closing system mainly consists of the die closing device, the die adjusting mechanism, the ejection mechanism and the front and rear fixed dies
 
It is composed of plate, movable formwork, mould closing oil cylinder and safety protection mechanism.
 
(3) Hydraulic system
 
The function of the hydraulic transmission system is to provide power for the injection molding machine according to the various actions required by the process, and to make the injection molding machine full of
 
Pressure, speed, temperature, etc. required for each part of the injection molding machine. It is mainly composed of various hydraulic components and hydraulic auxiliary
 
The auxiliary components are composed of oil pump and motor, which are the power source of injection molding machine. Various valves control fluid pressure and flow,
 
So as to meet the requirements of injection molding process.
 
(4) Electrical control system
 
The reasonable cooperation between the electrical control system and the hydraulic system can meet the process requirements (pressure, temperature
 
Speed, time) and various program actions. It is mainly composed of electrical appliances, electronic components, instruments, heaters, sensors, etc
 
Yes. Generally, there are four control modes, manual, semi-automatic, full-automatic and adjustment.
 
(5) Heating / cooling system
 
The heating system is used to heat the barrel and injection nozzle. Generally, the barrel of injection molding machine adopts the electric heating ring as the heating device
 
It is installed on the outside of the barrel and detected by thermocouple in sections. Heat conduction through cylinder wall provides heat for material plasticization
 
The cooling system is mainly used to cool the oil temperature. If the oil temperature is too high, many faults will occur, so the oil temperature must be
 
Control. Another place to be cooled is near the blanking opening of the material pipe to prevent the melting of the material at the blanking opening, resulting in the material
 
Can't cut normally.
 
(6) Lubrication system
 
The lubrication system is used to provide lubrication for the relative moving parts of the movable formwork, mold adjusting device and connecting rod hinge of the injection molding machine
 
In order to reduce energy consumption and improve the service life of parts, the circuit under sliding condition can be manually lubricated on a regular basis or
 
Automatic electric lubrication;
 
(7) Safety protection and monitoring system
 
The safety device of injection molding machine is mainly used to protect human and machine safety. Mainly composed of safety door, hydraulic valve
 
Limit switch, photoelectric detection elements, etc., to achieve electrical - Mechanical - hydraulic interlock protection.
 
The monitoring system mainly monitors the oil temperature, material temperature, system overload, and process and equipment failure of the injection molding machine,
 
In case of any abnormal condition, give an indication or alarm.
 
4、 Working principle and mode of injection molding machine:
 
The working principle of the injection molding machine is similar to the syringe used for injection. It uses the thrust of the screw (or plunger) to
 
The plasticized plastic in the molten state (i.e. viscous flow state) is injected into the closed mold cavity, and after solidification and finalization, it is obtained
 
Process of products.
 
Injection molding is a cycle process, each cycle mainly includes: quantitative feeding - melting and plasticizing - pressure injection
 
Injection mold filling cooling mold opening and taking parts. Take out the plastic part and then close the mold for the next cycle.
 
Injection molding machine operation items: injection molding machine operation items include control keyboard operation, electrical control system operation and hydraulic pressure
 
There are three aspects of system operation. Conduct injection process action, feeding action, injection pressure, injection speed and ejection respectively
 
Selection of type, monitoring of temperature of each section of barrel, adjustment of injection pressure and back pressure, etc.
 
Generally, the molding process of screw injection molding machine is: first, the granular or powdery plastic is added into the barrel, and
 
The rotation of the screw and the heating of the outer wall of the barrel make the plastic melt, and then the machine closes the mold and before the injection base
 
Move to make the nozzle close to the sprue of the mold, and then press the oil into the injection cylinder to push the screw forward
 
High pressure and high speed will melt