Discussion on sjz65 conical twin screw plastic ext

2022-08-03
  • Detail

On the elimination of electrical troubles of SJZ-65 conical twin-screw plastic extruder

sjz-65 conical twin-screw plastic extruder is one of the series products produced by Shanghai shenweida Plastic Machinery Co., Ltd. Its electrical system is mainly composed of main machine and auxiliary machine. The main machine part consists of the control of the main motor, the control of the feeding motor, the heating control and the spring feeding system. The auxiliary part consists of vacuum pump, water pump, mobile and traction device of setting table and cutting device

fault - foreign matters enter into the feeding screw barrel, resulting in the failure of the

feeding motor to operate normally. The feeding motor adopts sy series rare earth permanent magnet DC servo motor. 0.75KW, 160V, 5.6A, 1500 rpm. The speed regulating device is 512c speed regulating device of Continental Corporation of the United Kingdom. The faults of the feeding motor are generally manifested in the following aspects: 1. The motor cannot be started; 2. The motor speed is unstable. When the motor cannot be started, first check whether the power supply voltage is normal; Then check whether the emergency stop protection button is in the disconnected position; Whether the start button is normal; Whether overcurrent and loss of Excitation Protection Act; These faults are easy to handle. The motor speed is unstable for the following reasons: 1. The magnification of the speed ring of the main control board does not meet the requirements. You can adjust the rp5 potentiometer, but remember the original position. If it doesn't work, return to the original position. 2. The speed regulating potentiometer is not good: replace the potentiometer. 3 brush problem: check the brush wear and replace it with a new one. 4. Faults caused by other reasons. Generally speaking, the electrical fault of the feeding system is easy to handle, but an accident took me a lot of trouble. During a start-up production, the machine operator reported that the feeding motor had just started and stopped before it started. When I came to the site and opened the distribution box, I found that the overcurrent protection acted (the light-emitting diode v27 was on). After the protection was removed, the power was cut off and the power was transmitted again. After pressing the start button, the contactor was closed. It was normal. The potentiometer feeding motor was adjusted to accelerate. Suddenly, the reading of the ammeter rose sharply. Then there was no response, and the overcurrent protection acted again. Over current indicates that the load is too high, but during normal operation, the load carried by the feeding motor is very small. After its motor shaft is connected with a small gear gearbox, it pushes the single screw to feed. The current is generally below 2A. Release the motor line for no-load test (connect a 60 watt white woven lamp), restart, press the start button, the contactor is closed, the working indicator light is on, the rotary potentiometer accelerates normally, and the output voltage of the measuring control board 512c is normal, indicating that there is no problem with the speed control board. After troubleshooting the control system, start checking the motor. After measurement, the feeding motor was good, and the insulation was also OK. After removing the motor, the brush was checked to be OK. The motor was flexible to rotate by hand, and no abnormal sound was heard. Therefore, the fault point fell on the gear box. After removing the gear box, no problem was found. Things are at an impasse. Is it an internal problem of the motor? That would be a lot of trouble. The DC servo motor has a good sealing performance, and it also involves the speed measuring motor and brush device. Its disassembly is very difficult and carries certain risks. I stared at the motor and wondered what the problem was, and the maximum bending moment of the rectangular section specimen was on one side. Therefore, the rectangular section specimen can better show the material strength essence determined by the most dangerous defects? It suddenly occurred to me that there was another place that had not been inspected, the feeding screw and screw barrel. Could something fall into it? But the probability of a problem here is almost zero. So I asked the operator of the machine whether he found any abnormal conditions before driving and whether he had repaired other faults. The staff replied that one hour ago, the mechanical maintenance personnel repaired the spring loading. I affirmed my judgment even more. Sure enough, a finger sized spring block was found between the screw and the barrel wall. Take out the broken spring block, install the gear box, install the motor and connect the power line. Power on, drive, and the fault disappears. Later, after inquiry, the fault was caused by the error of the operator. According to the operation process, a magnetic frame should be placed at the bottom of the barrel to prevent iron foreign matters such as screws and gaskets from entering the barrel and causing damage to the equipment. However, after cleaning the safe and reliable sanitation of the drum brake, the operator forgot to put the magnetic frame back, and the feeding spring broke again, accounting for 13.9%; The equipment with a stroke of 500 ~ 900mm cracked, which eventually led to the failure. (see attached Fig. 1 for the electrical schematic diagram of the feeding system)

the bearing of the second traction motor is damaged, resulting in unstable speed of the traction system

the traction system of this machine uses a crawler tractor. Its function is to provide certain traction power and speed for the profiles extruded by the main machine with preliminary shape and size, and uniformly lead out the profiles. The tractor is composed of three systems: frame system, traction power system and pneumatic pressing system. The traction motor is a part of the traction power system. Two rare earth DC speed regulating motors are used. Its action process is B. The Application of fixture is highly effective. The traction motor drives the harmonic gear reducer through the synchronous pulley, and then transmits it to the sprocket on the crawler to form the power source of the traction machine. The traction motor is controlled by 512c speed regulating device of European company in Britain. The unstable speed of the traction system is generally caused by the following reasons: (1) there is a problem with the motor brush (including the speed measuring motor), the brush is out of place or produces large sparks. (2) There is a problem with the potentiometer. (3) Mechanical failure, lack of oil in gear box or gear damage. According to previous work experience, problems in the traction system of this machine are generally caused by the ignition of the brush, because it directly reflects that the speed fluctuates. Therefore, when the staff reported for repair, I handled it according to the previous method. First, the condition of the brush was checked, the pressure of the brush compression spring was adjusted, and two shorter brushes were replaced. Because the motor is sealed, I also use compressed air to blow away the brush powder inside. However, the fault still exists. I checked the speed measuring motor again, and there was no problem. So, remove the motor power cord (connect a 60 watt white woven lamp) and conduct no-load test. The measured output voltage of 512c is very stable, and the adjusting potentiometer is also very stable. In this way, the faults of speed regulating device and potentiometer are eliminated. Only the gear box has not been checked. The mechanical maintenance personnel were asked to open the gear box together. The lubricating oil inside was very dirty. After pouring it out, the gear was cleaned with gasoline. No problem was found. Reinstall and add new lubricating oil. The problem still hasn't been solved during power transmission and commissioning. It seems that it is still an electrical fault. After another careful inspection, the fault point was placed on the motor. With the approval of the leader, I removed a motor of the same model from another production line

Copyright © 2011 JIN SHI