2016年9月28日星期三

Concrete mixing plant And Common failure of concrete mixing station

working principle



Concrete mixing station is divided into four parts: gravel feed, powder (cement, fly ash, expansion agent, etc.) to feed, water and admixture feeding, transmission and storage and storage.The working process shown in Figure 1 , The mixer control system power, enter the man-machine dialogue interface, the system initialization processing, including the recipe number, concrete grade, slump, the production side, etc. According to the weighing of the silo, metering bucket Detection, the output material empty or material full signal, prompts the operator to determine whether to start the mixing control program. Start sand, stone belt motor feed to the metering bucket; open fly ash, cement tank butterfly valve, start screw motor transmission fly ash , The cement to the metering bucket; open the silo and admixture pool control valve so that water and admixtures flow into the metering bucket. Metering to meet the set requirements to open the metering Doumen, ingredients into the mixer has been started stirring mixing, to set Time to open the mixer door, concrete has been mixed into the mixer.
1. Each cylinder, control valve and motor are operated according to the requirements of the concrete mixing process. The control of each cylinder, control valve and motor must be accurate, stable and reliable.
2 control system with automatic, manual two modes of operation, and the relationship between each other is independent of each other constraints.
3 system has a good anti-interference ability and improve the alarm self-protection function.
4 through communication with the computer, you can display system operating status, fault alarm.
Gas supply failure
(1) air compressor failure are: check valve damage, piston ring wear serious damage to the intake valve and air filter plug.
To determine whether the check valve is damaged, just shut down the air compressor automatically after ten seconds, turn off the power to move a large tape wheel by hand, if you can more easily turn a week, then the check valve is not damaged ; In addition, the check valve has been damaged; In addition, the automatic pressure switch can also be exhaust from the exhaust below the situation to judge, usually in the air compressor automatically shut down after about ten seconds after the stop exhaust, If the exhaust has been in the air compressor until the start again to stop, then the check valve is damaged, to be replaced.
When the air compressor pressure rise is accompanied by a string of oil phenomenon, indicating that the air compressor piston ring has been seriously worn, should be replaced.
When the inlet valve sheet is damaged or the air filter is blocked, the air compressor pressure will rise slowly (but there is no string of oil phenomenon). If the suction is small, generally the air filter is dirty, the air filter is dirty. If the suction pressure is low, the air filter is dirty. If the air filter is dirty, The filter should be cleaned or replaced.
(2) pressure reducing valve failure: pressure is not high, or pressure rise slowly.
Pressure adjustment is not high, often due to pressure regulating spring fracture or diaphragm caused by rupture, must be renewed; pressure rises slowly, usually due to the filter is blocked, should be removed and cleaned.
(3) pipeline failure: pipeline joints leak, hose rupture, condensate accumulation.
Pipe joints leak and hose rupture from the sound up to determine the location of leakage, should be promptly repaired or replaced; if the pipeline in the accumulation of condensed water, should be promptly drained, characterized by condensation in the north of the winter easy to knot Ice and plug the gas path.
(4) Compressed air handling components (triple) of the fault are: oil-water separator failure, pressure regulator and oil mist device failure.
Oil-water separator failure is divided into the filter plug, damaged, moving parts of the sewage valve moving parts are not flexible and so on. Work should always clean the filter, remove the dirt inside the dirt and impurities.
The fault of the pressure regulating valve is the same as the above "(2) Failure of the pressure reducing valve".
Oil mist device failure phenomena are: not drop oil, oil cup at the bottom of the deposition of water, oil cup mouth seal damage. When the oil mist is not dripping, check whether the airflow of the air inlet is lower than the fog flow, whether the air leakage, oil adjustment needle is blocked, etc .; if the oil cup bottom water, should be excluded; When the sealing ring is damaged, it should be replaced in time.
Cylinder failure
Due to improper assembly and long-term use of the cylinder, the pneumatic actuator (cylinder) prone to internal and external leakage, the output power is not enough and the action is not smooth, poor cushioning, piston rod and cylinder head damage and other symptoms.
(1) the cylinder appears inside and outside the leak, usually due to eccentric piston rod installation, lack of oil supply, seals and seal rings wear or damage, the cylinder impurity and the piston rod caused by scars and so on. Therefore, when the cylinder inside and outside leakage, should re-adjust the center of the piston rod to ensure that the piston rod and cylinder coaxial; must always check the reliability of the work of the oil mist to ensure that the implementation of good lubrication components; Ring and seal ring wear or damage ring, must be promptly replaced; if there is impurities in the cylinder, should be promptly removed; piston rod when there is scar, should be renewed.
(2) the cylinder output force and the action is not smooth, usually due to the piston or piston rod is stuck, poor lubrication, air supply is insufficient, or the cylinder with condensed water and impurities and other reasons. In this regard, the center of the piston rod should be adjusted; check the operation of the oil mist is reliable; air supply pipe is blocked. When the cylinder has condensed water and impurities, should be promptly removed.
(3) cylinder cushioning effect is poor, usually due to buffer ring wear or damage caused by adjustment screw. In this case, replace the seal ring and adjustment screw.
(4) cylinder piston rod and cylinder head damage, usually due to eccentric piston rod or buffer mechanism does not work caused. In this regard, adjust the center of the piston rod position; replace the buffer seal or adjustment screw.
Reversing valve failure
Valve failure: valve can not be reversed or slow commutation, gas leakage, solenoid pilot valve failure.
(1) reversing valve can not be reversed or slow action is generally due to poor lubrication, the spring is stuck or damaged, oil or impurities stuck in the sliding part of the cause. In this regard, you should first check the work of the oil mist device is normal; the viscosity of lubricating oil is appropriate. If necessary, replace the oil, clean the sliding part of the valve, or replace the spring and the valve.
(2) valve after a long period of time easy to use spool seal wear, valve stem and valve seat damage phenomenon, resulting in valve gas leakage, the valve action is slow or not normal change and other failures. At this point, should replace the seals, stem and seat, or replace the valve.
(3) If the electromagnetic pilot valve into the exhaust vents are sludge and other debris blocked, closed lax, stuck active core, the circuit is faulty, can cause the valve can not be normal change. The first three kinds of conditions should be cleaned of the pilot valve and the activities of the core of the sludge and impurities. The circuit fault is generally divided into two types of control circuit failure and electromagnetic coil failure. Check the circuit fault, the valve should be manually turned a few knobs to see the rated pressure in the valve under normal commutation, if the normal commutation, the circuit is faulty. Check, the instrument can be used to measure the voltage of the solenoid coil to see whether the rated voltage, if the voltage is too low, should further examine the control circuit and the associated power switch circuit. If the change in the rated voltage valve can not be normal, you should check the solenoid coil connector (plug) is loose or contact is not real. Method is to unplug the plug, measuring the resistance of the coil (generally should be a few hundred ohms to several thousand ohms), if the resistance is too large or too small, indicating the solenoid coil is damaged, should be replaced.
Component failure
Pneumatic components failure are: oil mist device failure, automatic sewage device failure, muffler failure.
(1) the failure of the oil mist device: regulating the amount of needle adjustment is too small oil blockage, pipeline leakage and so will not liquid droplets atomization. In this regard, should be promptly dealt with congestion and leakage of the place, adjust the amount of drip oil to reach about 5 drops / min. Normal use, the oil cup to keep the oil in the upper and lower limits within. The bottom of the oil cup of water, should be promptly ruled out.
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