The EPE Foam Machine is one of the key main equipment in the refrigerator and freezer production line. According to the author's experience in the long-term maintenance of the EPE Foam Machine, the common mechanical failure of the important parts of the EPE Foam Machine is analyzed and the concrete lifting method The This article on the initial exposure to high-pressure foam machine maintenance personnel and high-pressure foam machine operators, maintainers have some guiding significance.
Foaming is a key process in the manufacture of household refrigerators and freezers. The quality of foaming directly affects the cooling effect of the refrigerator and the strength of the refrigerator, while the EPE Foam Machine is an important foundation for providing excellent foaming. EPE Foam Machine mainly consists of raw material tank, variable pump, high and low pressure valve, mixing head, hydraulic station, metering system and electrical control system. Common mechanical failure concentrated in the variable pump, mixing head, high and low pressure valve, hydraulic station and other components, this article one by one to analyze and describe.
Variable pump is the heart of high-pressure foam machine, the current use of mostly open axial piston pump, there are some closed pump in use. The plunger group of this pump is active, can swing around, its discharge volume and the pump is proportional to the angle of the axis, the greater the angle the greater the amount of spit, the amount of discharge and swing angle is basically a linear change. Closed and open variable pump can change each other, as long as the raw material pipeline to make a slight change on the line. Variable pump problems often flow instability, no flow output, pump noise, pump head leakage and other failures.
1.1 variable pump flow instability
The main reasons are: lack of pump input or pump plunger and the gap between the wall caused by too large. Variable pump suction may be due to filter dirty or raw tank preload pressure caused by too low, wash the filter and increase the pressure can be. Generally in accordance with the requirements of the process, the tank pressure should be controlled at 2.5-3.0BAR. If the low pressure cycle and high pressure cycle flow fluctuations are too large, this is the pump plunger and the gap between the inner wall is too large, need to replace the new pump. Also in the pump out of the mouth, there are several seals, if there is leakage, it will also cause instability. Variable pump rotation Whether the motor speed is balanced also affect the stability of the flow.
1.2 variable pump without process output
When the output of the variable pump suddenly becomes zero, it is likely that the disc-type shrapnel pressed between the oil pan and the piston head will lose its elasticity or the ring, replace the dish and re-install the retaining ring can. When the tank with a shallow groove on the complete wear and tear disappeared, only with the oil pan and with it with the piston head also scrapped. There is a channel between the end cap and the piston jacket to allow high pressure raw material to flow. There is a seal between the two faces. If it is broken, the variable pump output is gone.
1.3 variable pump noise
In the use of variable pump noise is also a common fault, the main reason for the temperature is too low lead to the viscosity of raw materials and raw materials in the gas too much (especially the combination of polyether) caused. The temperature is too low to open the heater by heating the raw material, you can also reduce the pressure of the mixing head, through continuous high pressure cycle to achieve raw material temperature. In order to avoid too much gas in the raw materials, raw materials should not work too much stirring, the raw material should not be too little tank, control in the tank 1/2. Another variable pump at the bearing group in the bearing group is broken, but also easy to produce noise, then replace the bearing on it. When the tank is expected, if the pump is also activated, it will produce harsh sound, easy to kill the pump scrapped, be careful not to play empty pump. In the electrical protection circuit is also set to place the high-pressure pump to run the situation.
1.4 variable pump leakage material
Variable pump shaft out of the pump outside the shaft seal often leaks, the need to regularly replace the shaft seal and sleeve, for shaft seal should pay attention to the direction and action to be soft, because the sleeve and shaft is the interference fit, Special tools, be careful not to put the stolen pump. When installing the sleeve to the sleeve to heat, with industrial hair dryer can, do not use acetylene heating. We must replace the shaft seal in the two shaft seal between the DOP, to prevent air intrusion and lubrication of the outer ring.
2. Mixing head
The mixing head is a mixture of two raw materials and infusion of the components, are now used are two piston L-type tip, and the first generation of single-piston tip compared to a mixed effect, splashing and other advantages. The main failure of the mixing head has a large piston death, oil spills, pressure fluctuations and so on.
2.1 mixed head to death
The main reason is that the gap between the large piston rod and the inner wall is too large, the surface of the large piston rod is rough, the foaming liquid is clean and the lubrication is not caused. The solution is to keep the mixing head clean and regularly quantitative in the piston rod and the outside of the Department to add DOP for its lubrication. The time and number of self-cleaning of the mixing head at the end of the pouring should also be adjusted according to the change of the cyclopentane, the change of the ambient temperature and the change of the pure white material composition.
2.2 mixing head of the oil spill
Solve the problem of oil leakage is to replace the seal. Special attention is the small piston shaft seal (because of its external oil drain is often blocked by the foam liquid, even if the shaft seal is not easy to find, resulting in hydraulic oil in the small cylinder open (that is, when the mixing head injection) There is to enter the bubble liquid, causing serious quality accidents, so to keep the small fuel tank drain hole open and check the replacement of the shaft seal.If the use of life is too long, so that the small piston rod with the gap between the inner wall is too large Which led to black and white material from the back to the trough of mutual penetration caused by the loop blockage, then only scrap this mixed head.
2.3 mixed head pressure instability
In the infusion of pressure instability is a common problem mixed head, mainly because the nozzle is dirty and the installation is not standardized, should be regularly cleaned, and other filters such as filtration accuracy is too low or damaged so that the stolen goods into the nozzle caused by pressure fluctuations, so the filter also Carefully check for damage and regular cleaning. Install the nozzle to clean the nozzle base, high and low pressure between the seal to ensure its integrity. As the viscosity of black and white material is not the same, in the high-pressure cycle in the small piston two return to the trough between the pressure difference, resulting in higher pressure of the white material to the lower pressure of the black material penetration, resulting in black material loop dirty block And the pressure is unstable, so to clear regularly.