When using the injection molding machine, there are many possible faults in the hydraulic system of the injection molding machine. It is the result of a combination of many factors, and its discreteness is relatively large. Therefore, in fault diagnosis, we must analyze the factors that cause faults one by one, pay attention to their internal relations and find out the main contradictions, so as to solve them easily.
Under normal circumstances, it is no accident that the hydraulic system of injection molding machine fails. Any failure will be accompanied by various abnormal omens before it evolves into a major failure. These omens can be summarized as follows:
(1) abnormal sounds appear, such as abnormal sounds of pumps, motors and temperature flow valves.
(2) The working speed of hydraulic motors for turning, walking and hoisting and hydraulic cylinders of various working devices are reduced and weak.
(3) The oil tank level drops and the oil deteriorates.
(4) Oil leakage appeared on the outer surface of hydraulic components.
(5) The oil temperature is too high.
(6) The pipeline is damaged, loosened and vibrated.
(7) The smell of focal nuclei appears, etc.
All these phenomena can be found by naked eye observation, hand touch and nose smell, as long as you pay close attention to them during use. In practical work, people use this on-the-spot method as the first-hand information to analyze faults, and then according to experience, integrate these first-hand information, make a concrete analysis of practical problems, find out the causes of faults and solve them as soon as possible. However, in practical work, it is often impossible to accurately diagnose the cause of failure at one time, so it needs several repetitions, that is, repeated analysis and repeated inspection, until the cause of failure is found.
In practical work, engineers and technicians often deal with faults in hydraulic system according to the following steps.
(1) understand the system. When a hydraulic fault occurs in an injection molding machine, we should first understand the hydraulic system, that is, we should be familiar with relevant technical data and reports, understand the working principle of liquefied gas pressure system, understand the basic structure of various components and the specific functions in the system, and be able to find out the liquid flow process under various working conditions. Before checking the equipment, observe the working condition of the system and record the necessary technical data, such as working speed, pressure, flow rate and cycle time.
(2) Ask the operator. Ask the operator who operates the failed injection molding machine. Ask about the characteristics of the equipment and its functional characteristics; Ask 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 it carefully. For the phenomenon proposed by the operator, it is further verified by observing the meter reading and working speed, monitoring the sound, and checking whether the oil and the actuator act incorrectly; Then carefully search from the oil tank along the loop in turn according to the liquid flow process in the system, and record and observe the knot on time. During inspection, carefully check the oil in the oil tank to determine whether dirt enters the system and affects the normal work of each component of the system; Touch by hand to check whether the oil inlet pipe and high-pressure oil pipe are preserved, softened, leaked or damaged; Check that the pipe joints of each control element and the mounting screws of the shell are loose one day; Finally, check the oil and piston rod of hydraulic cylinder. Attention should be paid to whether there is improper operation or maintenance during each inspection to find out the cause of the fault.
(4) List the possible failure causes according to the information obtained from understanding, inquiry, verification and inspection. At this time, it should be kept in mind that a fault phenomenon may be caused by two or more reasons, such as the speed reduction of the actuator, the wear of the hydraulic pump parts, or the increase of the internal leakage of the hydraulic cylinder; For another example, if the oil temperature is too high, it may be that the oil in the oil tank is not enough, or the oil pollution blocks the heat dissipation surface, or the pressure of the overflow valve is too high.
(5) draw a conclusion. According to the list of fault causes, according to the principle of "easy first, then difficult", the inspection sequence shall be discharged. First, select those equipment that can be restored to normal after simple inspection, verification or repair, so as to complete the inspection work in the shortest time.
(6) Verify the conclusion. Once through the above steps, find out the cause of the injection molding machine failure, and start troubleshooting. Troubleshooting includes checking pressure and flow rate with proper test device, disassembling cover plate of casing, and checking pump, motor and other components. These tests are the basis for judging replacement of parts and hydraulic components. In actual work, there is often no suitable test device to check, so it is necessary to replace the components such as pump, motor and hydraulic valve as an effective means to eliminate faults.
In the process of finding and troubleshooting, we should be serious, careful, prudent and try our best to be accurate, so as to avoid blindly disassembling parts or handling faults with inappropriate methods, so as to avoid causing new damage. Unless necessary, all hydraulic components must not be disassembled easily, because unnecessary and premature disassembly and assembly will reduce the service life of the
