Trouble shooting of platic injection molding machine lubrication

Injection molding machine lubrication system by the electronic control system, lubricating oil pump, lubricating oil (grease), oil pipe, lubrication distributor, lubrication point composition. The lubricating oil is compressed by the oil pump to the oil distributor and then distributed to each lubrication point to lubricate the moving parts of the injection molding machine. Injection molding machine with automatic centralized lubrication system, completed by the computer control, through the computer pressure relay monitoring lubrication status.

Injection molding machine commonly have constant resistance type lubrication system and quantitative pressure lubrication system.

Principle of constant resistance type lubrication :(small injection molding machine adopts constant resistance type) injection molding machine is equipped with damping type distributor, when the lubricating oil pump works, the pressure is generated from the oil pump outlet to the oil circuit of each distributor.

When the lubricating oil pressure is higher than the damping pressure difference, the lubricating oil will overcome the damping flow direction to each lubrication point until the end of the lubrication time. The size of the damping hole in the distributor is different, and the amount of oil allocated to each lubrication point is also different according to needs. When the pressure of the lubricating circuit cannot reach the pressure value set by the pressure relay during the lubrication time, the machine will give an alarm.

The principle of quantitative pressure lubrication :(the large injection molding machine adopts the quantitative type) the injection molding machine is equipped with the quantitative pressure distributor.

When the pressure of the lubricating oil circuit reaches the pressure set value of the pressure relay, the oil pump will stop working, the computer will start timing the lubrication delay, and each distributor will unload the pressure and automatically replenish the lubricating oil from the oil circuit to the upper chamber. After the timing of lubrication delay is finished, the oil pump starts again, and the total time of continuous stop lubrication ends.

Because the distributor can be different oil hole, to ensure that the amount of oil at each lubrication point is also on demand distribution.

The lubrication principle is introduced, and the common causes of lubrication failure are explained below in combination with daily maintenance.

1. Oil shortage alarm

When the oil tank is short of oil, the lubricating oil pump can't absorb oil and the pressure is insufficient, which leads to alarm. Add semi-liquid grease (lubricating oil) and lubricate manually. If there is no more alarm, the fault has been handled well.

Daily patrol machine to develop the habit of checking the lubricating oil box, observe the use of lubricating oil, active refueling or early detection of hidden dangers, can not wait for the lack of oil alarm to go passive refueling.

2. Oil alarm in the oil tank

Oil pump filter block, resulting in oil pump suction, insufficient pressure and alarm. Clean or replace, and replace qualified lubricating oil (grease).

The oil pump USES the waste oil for a long time. Repair oil pump or replace oil pump.

The author has seen many in order to save the cost blindly, with the waste liquid pressure oil or the old oil lubrication case. The old oil has not passed through the fine filtration, except the water, only under the simple precipitation, directly USES the oil tank. Old hydraulic oil impurities, viscosity is not enough, in fact, due to the role of lubrication. It will only accelerate the wear and tear of oil pumps and mechanical parts.

3. Oil pipe leakage

If the oil pipe joint at a certain point falls off or breaks, observe manual lubrication, find the oil leakage point, and repair the oil pipe.

4. Damaged or blocked oil distributor

Distributor pressure relay induction failure, clean distributor, if still not effective, replace a new distributor.

5. Switch of pressure relay is damaged

Replace it with a new one.

6. Broken signal line or poor contact

Repair damaged wiring or tighten connector terminals.

7. Improper parameter setting

Can enter the system screen with the password, modify the Settings.

In fact, the machine factory has a scientific and reasonable Settings, do not recommend not to agree to change the relevant lubrication parameters in the computer Settings, so as not to affect the lubrication of the machine.

Conclusion:

Failure to deal with the failure of lubrication is actually not difficult, if we do not pay attention to, do not actively deal with the failure, simply turn off the lubrication function on the computer or short lubrication detection alarm signal (it is the Ov signal line). Although the machine does not alarm, can work, but its hidden danger is great. Over time, it will inevitably affect the performance and life of mechanical parts. Our common copper sleeve, hinge pin, cross wear deformation, basically due to poor lubrication caused by serious failure.

We usually climb the machine hinge on the maintenance equipment or manipulator when the foot also show mercy, do not brutally crush the lubricating oil pipe, switch. The author has seen a workshop 27 injection molding machine in only 3 machine lubrication system is still working normally, the rest of the short, lubrication has become a device. There are also two large hinge pin limit screw injection molding machine, pressure block has broken, hinge pin has been out of the friction, Corinthian column scarred, a pile of iron debris.

Mechanical wear and tear caused by poor lubrication is a gradual process. Leaves don't turn yellow in a day. Use qualified lubricating oil (grease), add regularly, observe and inspect actively, the fault of lubricating oil path is actually very few.

The author learned that many imported brands of injection molding machine lubrication frequency and lubrication is dynamic change. It is controlled by computer system according to mold closing force, injection molding cycle, mold opening stroke comprehensive calculation to implement dynamic lubrication. Although different brands of injection molding machine lubrication pump structure slightly different, but its lubrication principle is the same, the maintenance method is much the same.