Fault and diagnostic steps of hydraulic system injection molding machine

Fault and diagnostic steps of hydraulic systems injection molding machine

When using an injection molding machine, the possible failures of the hydraulic system injection molding machine are diverse. It is the result of a combination of many factors, and the dispersion is relatively large. Therefore, when performing fault diagnosis, one must analyze the factors that cause the fault one by one, pay attention to their internal connections, and find out the main contradictions, so that they can be resolved relatively easily.

Under normal circumstances, the failure of the hydraulic system injection molding machine is not accidental. Any failure will be accompanied by various abnormal signs before it evolves into a major failure. These signs can be summarized as:

(1) There are abnormal sounds, such as pumps, motors, and thermostatic valves.

(2) The operating speed and weakness of hydraulic motors for slewing, walking, and hoisting, as well as hydraulic cylinders of various working devices, appear.

(3) The oil tank level drops and the oil deteriorates.

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

(5) The oil temperature is too high.

(6) Pipeline damage, looseness and vibration occur.

(7) The smell of focal nucleus appears

The above phenomena can be discovered by naked eye observation, hand touch, and nose smell as long as you pay careful attention during use. In actual work, people use this on-site method as the first-hand information to analyze the failure, and then based on experience, synthesize these first-hand information to analyze the actual problem and find out the cause of the failure as early as possible. Be resolved. However, in actual work, it is often impossible to accurately diagnose the cause of the failure at one time. At this time, several iterations are required, that is, repeated analysis and repeated inspections until the cause of the failure is found.

In actual work, engineering and technical personnel often follow the following steps to deal with faults in the hydraulic system.

(1) Understand the system. When a certain injection molding machine has a hydraulic failure, you should first understand the hydraulic system. It is to be familiar with relevant technical data and reports, understand the working principle of the liquefied pneumatic system, understand the basic structure of various components and the specific functions in the system, and be able to Find out the flow of liquid under various working conditions. Before inspecting the equipment, observe the working conditions of the system and record the necessary technical data, such as working speed, pressure, flow, cycle time, etc.

(2) Ask the operator. Interrogate the operator operating the malfunctioning injection molding machine. Ask about the characteristics of the equipment and its functional characteristics; ask about the basic phenomena when the equipment fails, such as whether the hydraulic pump can be started, whether the system oil temperature is too high, whether the system noise is too large, whether the hydraulic cylinder can drive the load, etc.

(3) Verify the phenomenon provided by the operator and check carefully. The phenomenon proposed by the operator is further verified by observing the meter readings, working speed, listening to the sound, checking whether the oil and actuators have malfunctions, etc.; then according to the fluid flow in the system, look carefully along the loop from the tank in turn, on time Record the observation. During the inspection, carefully check the oil in the fuel tank to determine whether dirt enters the system. It affects the normal operation of each component of the system; touch it by hand to check whether the oil inlet pipe and high-pressure oil pipe are proliferated, softened, leaked, or damaged; check each control The pipe joints of the components and the mounting screws of the housing are loose; finally check the oil and the piston rod of the hydraulic cylinder. In each step of the inspection, attention should be paid to whether there is improper operation or maintenance to find the cause of the failure.

(4) List the possible causes of failure based on the information obtained from understanding, inquiry, verification and inspection. At this time, it should be kept in mind that a failure phenomenon may be caused by two or more reasons. For example, the speed of the actuator is reduced, it may be due to the wear of hydraulic pump parts, or it may be due to the increase in internal leakage of the hydraulic cylinder; If the oil temperature is too high, it may be that the amount of oil in the fuel tank is not enough, or that the oil pollution blocks the heat dissipation surface, or the pressure of the overflow valve is adjusted too high.

(5) Make a conclusion. According to the list of failure causes, the inspection sequence is arranged according to the principle of “easy first, difficult second”. First select those that can be restored to normal after a simple inspection or repair, so that the inspection can be completed in the shortest time.

(6) Verification conclusion. Once through the above steps, find out the cause of the failure of the injection molding machine, start troubleshooting. Troubleshooting includes checking the pressure and flow with appropriate test equipment, disassembling the casing cover, and inspecting pumps, motors and other components. These test checks are the basis for judging the replacement of parts and hydraulic components. In actual work, there is often no suitable test device to carry out the inspection. At this time, it is necessary to replace the pump, motor, hydraulic valve and other component assemblies as an effective means of troubleshooting.

In the process of finding and troubleshooting faults, you should be careful, careful, cautious, and strive to be accurate, avoid blindly disassembling parts, or use improper methods to deal with faults, so as not to cause new damage. Except when necessary, do not disassemble hydraulic components easily, because unnecessary and premature disassembly and assembly will reduce the service life of these components.