Maintenance of injection molding machine

Date：2011/12/6 17:48:33

      Injection molding machine is commonly used in the plastics processing industry in one of the devices, usually it has to work long hours, so how to ensure continuous production of injection machine in the normal stability, both for the injection molding machine manufacturer or the user is a worthy and efforts to resolve the problem, the user point of view, the correct selection of injection models in context, regular preventive maintenance is to protect the injection machine to work as an effective way. The so-called preventive maintenance is a series of prevention and inspection, in order to avoid machine fails to extend the working life of some components, such as the sudden stop caused by the failure to anticipate and plan downtime can repair or overhaul; timely find and replace the damaged parts to prevent damage to the chain are all preventive maintenance work purposes. Meanwhile, in order to achieve the best performance and extend the life of injection molding machines, to improve the durability of the machine, the machine regularly check and make the appropriate repairs and maintenance is absolutely necessary.
        Preventive maintenance as follows:
        Production efficiency: reduce downtime and maintain normal operating speed can improve production efficiency;
        Machine precision; timely replacement of worn or worn parts can maintain the level of machine precision;
        Parts life: regular replacement of wearing parts, the proper adjustment and lubrication as well as the appropriate environmental conditions (temperature, humidity, dust adhesion) can extend the life of parts.
        Preventive maintenance
        Injection machine is a hydraulic, electrical, mechanical and other technologies in one device, with the maturity of technologies and development of the combination of the three is even more closely, the injection machine preventive maintenance work on the hydraulic press, electrical, mechanical, for three months are described.
        Hydraulic part of the
        Hydraulic oil
        Fuel shortage will lead to increased oil and easy, easy integration into the air to affect the oil and hydraulic oil systems of work, lack of fuel or oil spills are usually caused by the loss of repair, this routine should be aware that there is no leak check parts of the early replacement of worn seals, tighten loose joints, etc., repaired to check fuel tank, and timely supply.
        Hydraulic oil temperature
        Hydraulic system should be the ideal operating temperature range 45 degrees -50 degrees, because the hydraulic system is selected based on a design pressure of the oil viscosity, but viscosity will change with the level of oil, thereby affecting the system work components, such as cylinders, hydraulic valves, so that the control accuracy and response sensitivity decreased, the situation is even worse precision injection machine. Temperature will also accelerate the aging of seals make it harden, break-ups; the processing temperature is too low energy consumption, reduce the operating speed. Therefore, pay close attention to the hydraulic oil temperature is essential. The reasons for high oil temperature varied, but many attributed to oil cooling system failure or malfunction.
        Hydraulic oil quality
        One of the important properties of hydraulic oil is its chemical stability, that is, oxidation stability. Oxidation is to determine the effective life of hydraulic oil the most important factor, oxidation of wood tar, sludge and carbon residue and other insoluble materials can contaminate the hydraulic system, and increase the wear of hydraulic components, reducing the variety of the gap, to plug holes, which ultimately led hydraulic system failure. The oxidation rate depends on the hydraulic oil itself and the working conditions and other factors, of which temperature is the main factor, and therefore suitable hydraulic oil, hydraulic oil and regularly check the degree of oxidation (the color of the switch from oil to determine the deep ), more than a certain number of working hours after the oil change is absolutely necessary to take the initiative.
        Injection molding machine in use, the pressure should always check the oil level, oil pressure oil pump pressure and cleanliness of the wet weather, when the oil pressure must be checked daily concentrations at the same time need to always check the water pipes to prevent water mixed with the oil pressure inside, causing filter blockage. Always check the fuel tank, kept clean to prevent debris falling into. Added time pressure oil. For the lubrication of moving parts, the trip switch, screw tightness and the oil pipe, oil spills and other connector part is, once a week should be a routine inspection, in good condition and, if loose, then be replaced or tightened.
        In addition, a pressure oil to use for too long is too long, can replace the oil pressure, so in order to extend the oil valves, oil pump and seal life.
        Filter cleaning
        Filters play the role of clean hydraulic oil, so oil filter should be cleaned once every three months to keep the pump suction pipe flow at the same time check the oil network for damage. Filter specifications are usually no larger than 200 mesh.
        Cooler Cleaning
        Cooler should be cleaned once every two years, or according to their ability to work has reduced the cleaning, the cooler blocked or fouling will impact the cooling efficiency, cooling water should choose soft (no minerals) is better.
        Electrical part
        Check the wire connector
        Joints will not tighten the wire connector locations produce heat or sparks to damage, bad joints will also affect the signal transmission; contact with the connector on the result of electromagnetic vibration and easier to release the action, so the need to regularly check the cable connector fastening.
        Injection of various mechanical and electrical contact points way to keep tightening the state must not have slack. To avoid electrical box cooling, ventilation fans should always pay attention to the work performance, and timely clean-up Internet filters and replacement filters dust.
        The time required for electrical wire inside the connection points of all check to see whether the wire plastic shell hardening to prevent leakage.
        Electric motor
        General motors are air cooled, the dust may cause heat build-up problems, so regular cleaning every year, usually in the circuit is equipped with a motor overload cut off the device, the current limit protection device is adjustable, should be based on motor power to make appropriate choice, but once the overload starts, should be checked to determine whether the less-phase, high oil temperature or contacts after the bad press the reply switch.
         Heating tube and thermocouple
         Heating cylinder should be inspected are tightened to ensure effective heat transfer tube in the normal production in the burning heat is imperceptible, this work should pay attention to temperature control of the situation, from which to determine the heating tube is normal. Another is that heat damage to wire common tube connections, due to bad joints, contact resistance increases, leading to local overheating at the connection interface to oxidation damage.
         Often to maintain the thermocouple contacts clean.
        AC contactor
        Contactor for electric part of the action times more frequently because of its loss rate is also faster, if the main contact overheating may result in heating melting glue temperature control, so if there are contacts that overheating or breaking sound when issued a great fire, then the damage will be replaced as soon as possible.
        Computer-controlled part of the
        With computer control technology applications in the injection molding machine, micro electronic parts and related auxiliary board to work on the power supply voltage fluctuations, work environment, temperature, humidity, shock resistance as well as installation of high-frequency signal interference from the outside world are made a high demand for this to keep control box with ventilation fan is working, use a high precision regulated power supply equipment, try to reduce the control box to external vibration, and so is the basic requirement to work should address these issues effectively and regularly checked.
        Mechanical part
       1, the template parallel
        Template that best reflects the parallel clamping part of the state, the template does not cause product failure and the parallel increase in equipment and tooling wear. Template when the parallel end plates by clamping the movement and appearance of products is reflected in the initial analysis, but the exact circumstances, need to test other equipment with a dial indicator derived. Parallel adjustment of the template shall be familiar with the staff according to procedures, or improper adjustment of the machine more damage.
        2, the mold thickness adjustment
        You should periodically use mold thickness adjustment system, the mold thickness from the thinnest to the thickest to the callback time to ensure smooth operation, long-term production of machines with the same mold, this must be checked in order to avoid failure.
        3, the central lubrication system
        All mechanical moving parts needs to have proper lubrication, central lubrication system is one of the current injection molding necessary. Central oil lubrication system should pay attention to regularly check for fill, the use of lubricating oil to be clean and free of impurities to ensure that all locations of lubrication oil supply. When they find blockage or leaking pipes should be immediately replaced or repaired. Most are due to lack of lubrication of mechanical wear and tear occurred, and therefore paying enough attention to the lubrication.
        4, maintaining the smooth operation
        Smooth movement or vibration may be due to improper adjustment speed, speed changes and time does not match or mechanical, hydraulic adjustment caused. Mechanical parts such shock will accelerate wear and vibration have been tightening the screws, it should be reduced and avoided.
        5, bearing checking
        When the bearing part of the sound is different at work issue, or the internal temperature means that the bearing is worn, should be checked or replaced, and re-injected into the grease.
        6, the injection system
        Injection screw, check ring and barrel form the heart of the injection molding machine, determines the quality and efficiency of processing and must keep them in good working condition. First to take the necessary measures to prevent non-plastic debris mixed plastic materials, the addition should pay attention to check the screw and barrel, the check ring and barrel the correct gap, the gap should be sealed properly the plastic back and produce plastic of the required shear, When they find slow melt, melt spots and black spots, forming an unstable or product should check the screw, check ring and barrel wear.
        In addition to keep the motor clean and the oil valve, if there is dirt motor housing, it can lead to heat dissipation, should be checked once and found problems in a timely repairs, to play a role in ensuring the normal operation of the machine. If the machine will ring so long used the natural wear and tear, loss of a role or function played by bad hygiene oil spills, should be replaced in accordance with specifications. Also stop using the machine takes too long or to a different plastic injection molding, you must first barrel melt the remaining grounds clean and fine rubber, so that it can help smooth the process of melting plastic.
        The length of the life of the injection molding machine, injection molding machine manufacturer not only depends on the quality assurance of high quality, but also rely on the user's well-maintained, in order to improve its reliability and durability.
        Some common causes of failure and solutions
    Oil temperature is too high
        Abnormal rise in oil temperature may be normal or hydraulic cooling system components are not at work caused by heat generated.
        1, the cooling system is not normal
        1) cooling system supply, water valves not fully open, water pressure or pump flow does not meet the needs.
        2) plug the pipeline, such as filters, cooling tower or water blockage.
        3) cooling water temperature is too high, such as cooling tower cooling capacity is insufficient, or damage or temperature is too high.
        2, the hydraulic system to produce heat
        1) The pump is damaged, the internal parts rotating at high speed when the heat produced by wear.
        2) undue pressure regulator, a long period of high pressure hydraulic system overheating.
        3) leakage within hydraulic components, such as direction of the valve seal damage or damage that high-pressure oil flows through the small space heat.
        Noise generated
        Abnormal noise generation, that there are parts damaged or improperly adjusted, should identify the reasons for the location of the noise issue immediate repair.
        1, the lack of hydraulic oil tank, oil pump or oil filter dirt blocking the air inhaled can cause pump oil, causing the air bubbles in the oil leaves the noise impact, the solution is to check the oil, to prevent the inhalation of air and cleaning filter.
        2, hydraulic oil viscosity, increasing the flow resistance, need to replace the appropriate hydraulic oil.
        3, the pump or motor bearings or blade damage caused by the coupling concentricity deviation of the noise, have to adjust concentricity or replacement parts.
        4, the direction of the valve response to failure, but still features, such as heart valve wear, leakage, obstruction burr, movement is not flexible, solenoid valve failure due to insufficient current will generate noise. The solution is to clean the spool, spool to be replaced with new parts wear, and sufficient current to stabilize.
        5, hydraulic components, oil pipelines damaged or blocked so that the hydraulic oil high flow noise.
        6, mechanical failure, lack of lubrication or mechanical bearing wear or loose parts, should find out the reasons to tighten or replace parts, ensuring there is sufficient oil.
        Unstable or substandard products
        In a stable production cycle, the emergence of product quality unstable, mostly mechanical parts due to wear or improper adjustment.
        1, screw, check ring, barrel wear.
        2, the injection ring damage arising from the fuel tank leakage.
        3, the heating tube temperature control instability.
        4, pressure, speed control part of the disorder.
        Maintenance Summary
One. Daily maintenance issues
        1 machine sanitation
        2 oil
        3 toggle lubrication system
        4 heating system
        5 Cooling water transport
        6 emergency stop
        7 effect of security agencies
Two. Weekly maintenance issues
        1 trip, check the proximity switch
        (2) permeability
        3 Huang Yourun sliding part of the
        4 screw loose
        5 oil
Three. Quarterly maintenance issues
        1 wire connector
        (2) electric box health
        3 pump, motor oil
        4 butter
        5 Power
Four. Annual maintenance matters
        1 tank and the oil pressure
        (2) of wire insulation
        3 electric motor
        4 Injection Screw
        5 toggle
Adjustment of the injection molding machine
  
        Injection molding is an engineering, involving the contents of the plastic into useful and can maintain the original performance of the products. Important injection molding process conditions affect the flow of plastics and cooling temperature, pressure and the corresponding time for each role.
First, the temperature control
        1, the barrel temperature: injection molding process requires a temperature controlled barrel temperature, nozzle temperature and mold temperature. The first two temperature mainly affects the plastics and plastic flow, the latter mainly affects the temperature of plastic flow and cooling. Each has a different kind of plastic flow temperature, the same kind of plastic, because different sources or grades, the flow temperature and decomposition temperature there is a difference, which is due to different average molecular weight and molecular weight distribution caused by different types of plastic injection inside the plasticizing process is different, so choose the barrel temperature is not the same.
        2, the nozzle temperature: nozzle temperature is usually slightly lower than the highest temperature of the barrel, which is to prevent the melt in the nozzle may occur through the "drooling phenomenon." Nozzle temperature can not be too low, otherwise it will result in the early condensate and melt the nozzle closed, or due to early condensate material into the mold cavity and affect the performance of products
        3, mold temperature: mold temperature on the product's inherent quality of performance and apparent influence. Mold temperature is decided in the plastic crystalline availability, products, size and structure, and performance requirements, and other process conditions (melt temperature, injection speed and injection pressure, the molding cycle, etc.).
Second, the pressure control: the process of pressure injection pressure and injection pressure of two kinds of plastics, and plastics and plastic directly affect product quality.
        1, the plasticization pressure: (back pressure) using screw-type injection machine, the screw top of the melt in the screw turning back when the pressure is called the plasticization pressure, also known as back pressure. The size of this pressure can be achieved through the pressure relief valve in the hydraulic system to adjust. The injection, the plasticization pressure, the size is the speed with the screw all the same, an increase of plastics that will increase pressure the temperature of the melt, but will reduce the rate of plastics. In addition, the increased pressures of plastics can melt temperature uniformity, the pigment mix and melt in the gas discharge. Normal operation, the plasticization pressure, the decision should be to ensure good quality products under the premise of the lower the better, its specific value is used in plastics with different varieties, but usually less than 20 kg / sq cm.
        2, injection pressure: in the current production, almost all of the injection machine injection pressure are based on the plunger or screw top plastic by the pressure (pressure from the oil conversion to a) the subject of. Injection pressure in injection molding the role is to overcome the flow of plastic from the barrel cavity flow resistance, given the rate of melt filling and compaction of the melt.

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