Reciprocating piston air compressors play an extremely important role in the flexible packaging plastics industry. For example, when making a bag, it is used on a punching machine for air punching and punching; when printing plastic, it is also used on a cylinder to lift and lower the offset press roller. The reciprocating piston compressor has excellent performance, low noise, low fuel consumption and low specific power. However, it is easy to reduce the exhaust gas, high exhaust gas temperature, high oil temperature, knocking sound, piston stuck or biting in production. Stay and wait for the fault. Reciprocating piston air compressors play an extremely important role in the flexible packaging plastics industry. For example, when making a bag, it is used on a punching machine for air punching and punching; when printing plastic, it is also used on a cylinder to lift and lower the offset press roller. The reciprocating piston compressor has excellent performance, low noise, low fuel consumption and low specific power. However, it is easy to reduce the exhaust gas, high exhaust gas temperature, high oil temperature, knocking sound, piston stuck or biting in production. Stay and wait for the fault.
First, the working principle of reciprocating piston air compressor Reciprocating piston air compressor is generally driven by a motor to rotate the shaft through the V-belt, and then the piston is driven by the connecting rod to reciprocate, so that the piston chamber volume composed of the valve, piston and cylinder Changes occur to achieve the purpose of compressed air. The compressed air is compressed by the intercooler and finally enters the gas storage tank.
The gas storage tank is mainly composed of a cylinder body, a pressure gauge and a safety valve, which can stabilize the pressure of the air pipeline and reduce the pressure fluctuation caused by the compressor working. If the internal compressed air exceeds the rated air pressure for some reason, the safety valve will automatically open to discharge the compressed air into the atmosphere to ensure safe operation. Our factory uses V-0.3/10 and W-0.6/10 air compressors produced by Fujian Compressor General Factory. The opening pressure of the safety valve is 1.05~1.08 times of the rated exhaust pressure. Of course, the opening pressure of the safety valve is different for air compressors of different specifications.
Second, the pre-production inspection Before starting the air compressor, it is necessary to do some inspection to eliminate the hidden troubles. The inspection before starting mainly includes the inspection of the power supply voltage and the inspection of the oil level.
Power supply voltage: The fluctuation range of the power supply voltage is required to be ±5%.
Oil level check: The oil level is generally 1/3 to 2/3 of the oil mark. When it is lower than 1/3 of the oil mark, the filtered oil of the same grade should be added in time. 13# compressor oil should be used in winter and 19# compressor oil in summer. SAE30 can be used at a temperature of 10 ° C or higher, and SAE 10 can be used at 10 ° C or less.
Third, the reduction of exhaust volume 1. Lack of oil The reduction of exhaust volume has a direct relationship with oil shortage.
Once we were in production, the air compressor had a problem of reduced exhaust gas volume, which not only failed to raise and lower the press roller of the printing press, but also accompanied by a certain knocking sound. We first inspect the air muffler and clean it, then observe the oil level, find that the oil level is lower than 1/3 oil level, immediately add the same grade of oil, then start the power switch, try to open, still have Knocking. Later, the crankshaft, connecting rod, piston and cylinder of the moving mechanism components were dismantled and inspected. It was found that the crankshaft had cracks, and it was seen that it was broken quickly. It must have been short of oil for some time. Due to lack of oil, the moving parts are dryly rubbed, and the overload operation causes the parts to be damaged to varying degrees. We cleaned and grinded the moving parts of the damage, severely replaced them, reinstalled and tested the machine, the knocking sound disappeared, and the displacement was normal. It can be seen that the oil is absolutely indispensable, otherwise it will be endless.
2. The air noise filter and the air valve are not tight enough. The reduction of the exhaust volume is also related to the tightness of the air noise filter and the air valve. The air muffler filter must be cleaned up. Cleaning the dirt on the valve plate and the valve plate is beneficial to the air compressor to ensure the normal exhaust volume. The filter should be cleaned every 200 hours under normal conditions, and the valve should be cleaned every 500 to 800 hours.
3. The quality of the lubricating oil is not good. The poor quality of the lubricating oil will cause the piston ring to be sucked, thus reducing the displacement. Therefore, you should choose a high quality lubricant. After long-term work, the lubricant will contain impurities, dust, etc., so it is also filtered. Generally, the oil should be replaced every 500 to 800 hours, and the oil used in the previous time should be filtered.
4. Exhaust gas temperature is too high Excessive exhaust gas temperature will also cause the piston ring to be sucked, resulting in a decrease in exhaust gas volume. As long as the temperature is lowered, the problem can be solved. There are two things to note here:
(1) The ambient temperature should not be too high, generally not exceeding 40 °C.
(2) If the gas valve leaks, the discharged high temperature gas will return to the cylinder. At this time, we should carefully check the gas valve, grind the valve plate or replace the valve plate to eliminate the air leakage phenomenon, so that it is possible to solve the problem of high temperature.
Fourth, the cause of the crash phenomenon and countermeasures Air compressor is also prone to "dead" phenomenon during the operation. The cause of the air compressor "crash" comes from both electrical and mechanical aspects.
1. Electrical reasons The electrical part of the air compressor is mainly composed of an electric motor and a pneumatic automatic switch. The pneumatic automatic switch is closed when the air compressor is operating normally. When the pressure of the gas storage tank reaches the rated exhaust pressure, the compressed air pushes the rubber, and the spring jumps through the jump bridge, so that the movable contact and the static contact in the bakelite seat are disengaged, the circuit is cut off, and the motor is stopped. Conversely, when the tank pressure is reduced to a certain value, the spring springs back, the circuit is turned on, and the motor is running (see Figure 1).
If the contactor C coil is not energized, the air pressure switch will not work, resulting in a "dead" phenomenon. For example, when there is a phase loss, the power switch K cannot be closed, and the coil C is not energized, resulting in a "dead" phenomenon.
2. Mechanical reasons The mechanical causes of the "dead" are: the connecting rod is broken, the piston is stuck in the cylinder and the piston assembly gap is too large, too small.
Most of the connecting rod breakage is related to overload operation, so overload operation should be avoided to avoid breakage of the connecting rod. At the same time, attention should be paid to the assembly clearance and lubrication status of the cylinder and piston.
In addition, when the air compressor is not in use, the drain valve at the bottom of the gas tank should be opened and the sewage discharged. If it is not used for a long time, it should be protected against moisture, keep the valve and oil seal clean, and apply oil to the surface openings of cylinders, pistons, etc., and seal it with oil paper. In short, to ensure that the compressor is running well, life is extended, and daily maintenance and maintenance are very important. At the same time, the maintenance workers must have a strong sense of responsibility, and early detection of faults should be eliminated early.
Paper cutter failure and blade sharpening Some small faults caused by the blade in the paper cutting often make many operators unable to find the clue, can not find the problem, the following excerpts for peer reference.
Fault 1. The freshly ground blade is put into use, and there is no hard foreign object in the cutting, but it will suddenly collapse a little.
The main reason for this problem is that the cutting edge is not properly controlled during the grinding process (the amount of the infeed is too large), causing the temperature to be too high during the grinding process (ie, the temperature at the contact point between the blade and the grinding wheel is too high). The blade is "burned out".
Fault 2. The cutter does not cut to the end when cutting.
This is mainly due to the excessive straightness of the edge of the knife.
Fault 3. The blade has just been used after sharpening. The cut surface of the cut paper has a knife, or the cutting process is poor.
This is mainly due to the blade being too soft due to overheating of the sharpening.