Injection molding machine lubrication system consists of lubricating oil pump, lubricating oil, oil pipe, lubrication distributor, lubricating point. Lubricating oil is compressed by oil pump to oil distributor and then distributed to each lubrication point, so as to achieve the purpose of lubricating all moving parts of injection molding machine. With automatic centralized lubrication system, controlled by a computer to complete, through the computer to monitor the pressure relay pressure lubrication.
Injection molding machine is the most common fixed resistance lubrication system and quantitative pressurized lubrication system of these two.
Fixed resistance lubrication principle: (Small injection molding machines use fixed resistance type) Injection molding machine equipped with a damping distributor, when the lubricating oil pump work, from the pump outlet to the distributor of the oil pressure.
When the oil pressure is higher than the damping pressure difference, the oil will overcome the flow of damping oil to each lubrication point until the lubrication time is over. The size of the orifice in the distributor varies with the amount of oil distributed to each lubrication point. The machine will alarm when the pressure of the lubricating oil circuit can not reach the pressure set by the pressure relay during the lubrication time.
Quantitative pressurized lubrication principle: (large-scale injection molding machine with quantitative) injection molding machine is equipped with a quantitative pressure distributor, when the pump is working, the pump pressure to the distributor, the quantitative distributor of the cavity pressure on the oil The lubrication points, uniform lubrication of all parts.
When the pressure of the lubricating oil reaches the pressure setting value of the pressure relay, the oil pump stops working, the computer begins to lubricate and delay the time counting, and the distributors depressurize and automatically replenish the oil from the oil path to the upper chamber. After the pump started again, round the clock until the end of the total lubrication time.
Due to the distributor of the oil discharge holes can be different to ensure that the lubrication points of the oil is also allocated on demand.When the lubricant pressure in the lubrication time can not reach the relay pressure setting, the machine receives the feedback signal and alarm : Lubrication failed!
Introduced the lubrication principle, the following combination of the author's daily maintenance notes, explain the common causes of lubrication failure.
1. Missing alarm
When the oil tank is lack of oil, the lubricating oil pump can not absorb oil and work under pressure due to lack of pressure, adding semi-liquid grease (lubricating oil), manual lubrication, if no alarm, indicating that the fault is handled well. Is the pump inhaled air, oil in the gas lead to this time, open the oil pump outlet, manual lubrication, the oil pipe after the exhaust can be tightened.
Routine inspection to develop a good habit of checking the fuel tank, observe the use of oil, take the initiative to find out lubrication or early detection of hidden dangers, can not wait until the lack of oil alarm to go passive refueling.
2. Oil tank alarm
The pump filter clogged, causing the pump to absorb oil, the pressure is insufficient and the alarm.This failure is mostly due to the use of unclean oil or old oil or low quality oil.Remove the pump on the filter, with a copper brush , Kerosene cleaning filter and suction port, cleaning the tank, and replace the qualified lubricants (fat).
Oil pressure shortage alarm Adjust the right side of the pressure relief valve in the figure below, with a flat-face screwdriver clockwise to increase the amount of large oil drain, turn counterclockwise to reduce the amount of small oil, then reverse the small amount of oil displacement. Drain port must have oil overflow, neither large nor large, the oil port pressure becomes smaller; no oil discharge, the oil pipe is easy because of the large, is not conducive to relubrication from the pressure. Relief valve oil spill appropriate.
If this method is still not improved, some pump relief valve port filled with spring and marbles structure may be spring marbles stuck by impurities, remove the cleaning can be.
Clean the filter, adjust the pressure relief valve, after cleaning, although there is oil outflow from the pump outlet, but the pressure gauge shows the lack of pressure, the machine alarm.It is possible to long-term use of oil pump waste oil, worn oil leakage, resulting in Insufficient pressure. Repair the pump or replace the pump.
I have seen many in order to blindly cost savings, the use of waste hydraulic oil or oil lubrication case. The old oil without fine filtration, in addition to water, only a simple precipitation, with direct fuel tank. Old hydraulic oil impurities, viscosity is not enough, In fact, the lubricating effect should not be achieved. It will only accelerate the wear and tear of oil pumps and mechanical parts.
3. Oil pipe leakage
A certain point of the oil pipe fittings fall off or damaged oil leakage, resulting in the failure of the pressure relay induction. After clamping, manual lubrication observation, to find the oil spill point, the maintenance tubing.
4. Oil distributor damaged or blocked
Resulting in the distributor pressure relay induction failure, after cleaning the dispenser with kerosene can adjust the metering nut pressure regulator, so that the telescopic rod can be pressed to the relay switch is still not effective, the replacement of a new distributor.
5. Pressure relay switch is damaged
Test the switch with a multimeter, replace the new broken.
6. Signal line open or poor contact
Use a multimeter to find the point of failure, repair damaged wiring, or tighten the connector terminals.
7. Improper parameter setting
Lubrication failure during production alarm, check the pump, oil, lines, no abnormalities.Check the computer signal, the computer controller found no signal output, still no response when manual lubrication, which may be parameter setting problem. Value is small, the lubrication modulus has reached its set value, you can enter the system screen password, find the modulus of lubrication, set the value of the larger point on it.
Quantitative pressurized lubrication time is actually lubrication alarm time, lubrication time should be longer, there is enough time to ensure that the pressure relay from the pressure, thus avoiding the set lubrication alarm time is too short and false alarm.
In fact, the factory has a scientific and reasonable factory settings, do not agree with the computer is not in favor of changing the settings related to lubrication parameters, so as not to affect the lubrication of the machine.
to sum up:
Lubrication failure troubleshooting is not difficult, if we do not pay attention, do not actively deal with the failure, simply turn off the lubrication function on the computer or short lubrication warning alarm signal (which is Ov + signal line). Although the machine does not alarm, you can Work, but its hidden dangers. Over time, will inevitably affect the performance and life of mechanical parts. Our common copper sleeve, hinge pin, cross wear and tear, are basically due to poor lubrication caused serious failure.
We usually climb the hinge on the maintenance of equipment or mechanical hand when they have their feet mercy, do not savagely trample on dirty oil pipe, the switch I have seen 27 injection molding machine in a workshop only 3 machine lubrication system is still working, the rest All shorted, lubrication has become a decoration. There are two injection molding machine hinge hinge limit screw, the pressure block has broken, the hinge pin has been out of the friction of Corinth column scar, a bunch of iron filings.
Damage caused by poor lubrication is a gradual process of change.Are the so-called, the leaves are not yellowing one day.Use qualified lubricants (fat), add regularly, take the initiative to observe the inspection, the lubricating oil road fault is very little .
I understand that many imported brands of injection molding machine lubrication frequency and the amount of lubrication is dynamic.It is controlled by the computer control system based on clamping force, injection molding cycle, a comprehensive calculation of the open stroke to implement dynamic lubrication.Although different brands of injection Machine lubricating oil pump structure is slightly different, but its lubrication principle, maintenance methods are similar.