Equipment that uses plastic molding molds to make thermosetting plastics or thermoplastics into plastic products of various sizes, forms, and uses is an injection molding machine. In order for an injection molding machine to complete its main function of making plastic products, it must require hydraulic control part of injection molding machine to perform its normal functions.
Based on importance of hydraulic control of injection molding machine in equipment of injection molding machine, author analyzed characteristics of cylinder in hydraulic system of injection molding machine, aiming to find an effective way to maintain hydraulic system and cylinder of injection molding machine, so as to achieve purpose of better use of plastic processing industry, promote social construction and economic development.

Injection molding machine is a device that uses plastic molding molds to make thermosetting plastics or thermoplastics into various finished products of different sizes, different forms, and different uses.
In our daily life, common injection molding machines are mainly divided into three categories: all-electric injection molding machines, vertical injection molding machines, and horizontal injection molding machines. Although these three types of injection molding machines have subtle differences in use, but in terms of their composition, general injection molding machines are composed of hydraulic transmission system, injection system, mold clamping system, heating and cooling system, lubrication system, safety monitoring system, electrical control system, etc.
Reason why injection molding machine can produce a variety of different plastic products is because various systems of injection molding machine cooperate to turn plastic into a molten state, then hydraulic high-pressure system of equipment is used to inject molten plastic into pre-prepared mold cavity.

 

In order for an injection molding machine to complete its main function of making plastic products, it must require hydraulic control part of injection molding machine to perform its normal functions. Based on importance of hydraulic control of injection molding machine in equipment of injection molding machine, I made statistics on structural characteristics of hydraulic system of injection molding machine hydraulic system.

In order to explore structural characteristics of hydraulic system cylinder of injection molding machine and ways of maintenance, I conducted a research on structure of piston cylinder of injection molding machine. I found that main components of a piston cylinder are: piston, cylinder block, end plate, seal ring and piston rod. Because piston cylinder itself has certain advantages, piston cylinder is mostly used in hydraulic transmission system. In the process of studying piston cylinder, I found that working principle of piston cylinder is mainly: hydraulic oil is alternately delivered to both sides of piston in cylinder, reciprocating movement of piston is realized by pressure difference between hydraulic oil on both sides of piston.

In order to explore structural characteristics of hydraulic system cylinder of injection molding machine and ways of maintenance, I conducted a research on structure of piston cylinder of injection molding machine. I found that main components of plunger cylinder are: plunger, cylinder block, guide sleeve, end gland and sealing rubber ring. When studying plunger cylinder, I found that main difference between piston cylinder and plunger cylinder is that piston type of piston type cylinder and plunger type cylinder are different, piston type of latter uses a cylindrical piston. It also determines intelligent use of plunger cylinders in transmissions with long mechanical strokes.

When compound cylinder is working, hydraulic oil enters cylinder from plunger hole, so that mold clamping device moves forward quickly; when mold clamping is close to end, when mold clamping cylinder (piston cylinder) enters hydraulic cylinder, stroke speed slows down, so that clamping force reaches required tonnage. This kind of plunger and piston cylinders are called composite cylinders.

After studying structural characteristics of hydraulic cylinder of injection molding machine, I combined my own practical experience with a lot of theoretical analysis, formulated maintenance countermeasures for hydraulic system of injection molding machine and cylinder according to structural characteristics of hydraulic system of injection molding machine. In process of analyzing maintenance plan of hydraulic system cylinder of injection molding machine, maintenance of hydraulic system cylinder of injection molding machine developed is mainly formulated for common faults of hydraulic system and cylinder of injection molding machine.
1. In order to ensure that hydraulic cylinder of injection molding machine is in daily use, there will be no leakage at piston rod of hydraulic cylinder and hydraulic transmission joint, so in daily use of hydraulic system of injection molding machine, we can avoid leakage accidents by regularly checking joints of hydraulic system of injection molding machine for leakage. Once in the process of checking hydraulic system of injection molding machine, it is found that hydraulic system of injection molding machine is leaking. Leaking part must be repaired in time, and leaked oil should be cleaned in time.
2. When installing pipeline, it is necessary to clean, level flange end face and thread. When fixing screws, pay attention to even force.
3. Control working temperature of hydraulic system of injection molding machine to ensure that working temperature does not exceed 55 degrees Celsius. Once system temperature rises, system must be cooled by cold water cooling method.
4. During use of injection molding machine, always check oil level of pressure oil, pressure of oil pump and cleanliness of pressure oil. When encountering humid weather, concentration of pressure oil must be checked daily, water pipes must be checked frequently to prevent water from mixing into pressure oil and causing oil filter to be blocked. Check fuel tank frequently to keep it clean and prevent debris from falling in. When oil level is not high enough, pressurized oil should be added in time. For lubrication of all moving parts, each travel switch, each oil hose, and joint parts for oil leakage, a routine inspection should be carried out once a week.
5. Hydraulic oil should be replaced in time according to requirements of operating procedures of injection molding machine (generally one to two years, depending on working conditions), oil tank and oil filter should be cleaned to prevent oil circuit from blocking equipment, equipment is not running smoothly.

Reasonable, effective and scientific maintenance of hydraulic cylinder of injection molding machine is a prerequisite to ensure efficient operation of injection molding machine. Only plastic manufacturers can achieve safe and stable production through reasonable and effective maintenance of hydraulic cylinder of injection molding machine.