Injection molding machine hydraulic system troubleshooting steps

When using an injection molding machine, the possible failures of the injection molding machine's hydraulic system are various. It is the result of a number of factors, and the dispersion is large. Therefore, in the fault diagnosis, we must analyze the factors causing the fault one by one, pay attention to their internal links, and find the main contradiction, so that it can be relatively easily resolved.

Under normal circumstances, it is no accident that the hydraulic system of the injection molding machine is faulty. Any failure before it evolves into a major failure is accompanied by various kinds of abnormal omens. These omens can be summarized as follows:

(1) Abnormal sounds, such as abnormal sound in pumps, motors, thermostat valves, etc.

(2) There is a drop in speed and weakness in the hydraulic cylinders of turning, walking, hoisting hydraulic motors, and working devices.

(3) There is a drop in fluid level in the tank and deterioration of the fluid.

(4) Oil leakage on the outer surface of the hydraulic element.

(5) The oil temperature is too high.

(6) Pipe damage, looseness and vibration.

(7) A coke core odor, etc.

These phenomena, as long as careful attention during use, can be found by naked eye observation, hand touch, nose sniffing. In the actual work, it is through this on-site means that people use it as first-hand information for analyzing faults. Based on experience, these first-hand data are then integrated to analyze the actual problems and find out the cause of the failure. Solve it. However, in actual work, it is not always possible to accurately diagnose the cause of a fault once. At this time, several iterations are required, that is, repeated analysis and repeated inspection until the cause of the fault is found.

In actual work, engineers and technicians often deal with the faults in the hydraulic system in the following steps.

(1) Understand the system. When an injection molding machine has a hydraulic failure, it is first necessary to understand the hydraulic system. Is to be familiar with the relevant technical information, reports, understand the working principle of liquefied air pressure system, understand the basic structure of various components and the specific functions in the system, to find out the flow process under various working conditions. Before checking the equipment, you should first observe the working conditions of the system and record the necessary technical data, such as working speed, pressure, flow rate, cycle time and so on.

(2) Ask the operator. The operator who manipulated the failed injection molding machine was asked. Inquire about the characteristics of the equipment and its features; ask the basic symptoms of the equipment failure, such as whether the hydraulic pump can start, whether the system oil temperature is too high, the system's noise is too large, whether the hydraulic cylinder can drive the load.

(3) Verify the operator-supplied phenomenon and examine it carefully. The phenomenon proposed by the operator is further verified by observing the meter reading, working speed, monitoring sound, checking the oil and the actuator for any malfunction, etc., and then carefully searching the circuit according to the flow process in the system from the tank in turn. Record observations were stagnant. During the inspection, carefully check the oil in the tank to determine if dirt has entered the system. Influencing the normal operation of each component of the system; by hand, inspect the inlet pipe and the high-pressure fuel pipe for defects, softening, leakage, and damage; check the fittings of the control elements and the mounting screws of the housing for loosening; check the oil and Hydraulic cylinder piston rod. In each step of inspection, attention should be paid to whether there is any operation or improper maintenance to find the cause of the fault.

(4) List the possible failure cause tables based on the information obtained from the knowledge, inquiry, verification, and inspection. In this case, it should be borne in mind that a malfunction may be caused by two or more causes. For example, the speed of the actuator may be reduced due to the wear of the hydraulic pump components or due to the increased internal leakage of the hydraulic cylinder. If the oil temperature is too high, the amount of oil in the fuel tank may not be enough, or the oil contamination may block the heat dissipation surface, or the pressure of the relief valve may be adjusted too high.

(5) Make a conclusion. According to the list of failure reasons listed, the inspection order shall be discharged in accordance with the principle of "difficulty first and then difficult". Select the ones that can be returned to normal after a simple inspection, verification, or repair to complete the inspection in the shortest possible time.
(6) Verification conclusions. Once you have gone through the above steps to find out the cause of the failure of the injection molding machine, start troubleshooting. Troubleshooting includes checking the pressure and flow with a suitable test device, removing the housing cover, and checking the pump, motor, and other components. These test checks are the basis for determining the replacement of parts and hydraulic components. In practice, there are often no suitable test devices to perform the inspection. At this time, it is necessary to replace components such as pumps, motors, and hydraulic valves as an effective means of troubleshooting.

In the process of finding and resolving faults, it is necessary to be careful, careful, prudent, and accurate in order to avoid blindly disassembling components or dealing with faults with inconvenient methods so as to avoid causing new damage. Except when necessary, the hydraulic components must not be easily dismantled because unnecessary and premature disassembly will reduce the service life of these components.