After the screw barrel is used for a period of time, the screw edge and the nitrided layer of the barrel (when making a new screw, both the screw and barrel will be subjected to nitriding heat treatment, so there will be a nitride layer of about 30-60 filaments on the surface ) It is worn in both directions, and the gap between the two sides increases, causing the problem of poor and unstable plastic products. Screw refurbishment is to increase the thickness of the screw edge on the old screw to fill in the gap to achieve the purpose of increasing the output.

　　 There are currently three main refurbishment methods in China:
　　 (1) Electric welding: electric welding with alloy electrode (20-30 yuan/kg)
　　 Disadvantages: not abrasion resistant, easy to appear false welding, the surface is not smooth, there will be blisters, the pellets will stay in the screw, resulting in yellow small burnt blocks and black spots.
　　 (2) Spray welding: spray alloy powder with a special "acetylene-oxygen" spray gun (30-50 yuan/kg)
　　 Disadvantages: no wear resistance, blisters, part of the alloy is not completely melted during the spray welding process, and the alloy powder will come out of the material during the use process, resulting in material leakage and damage to the die
　　 (3) Surfacing welding: use "acetylene-oxygen" to completely melt the 300 yuan/KG imported alloy electrode on the screw
　　Advantages: Because it is melting, there is no false welding or blistering.
1. After using the machine for a period of time, a comprehensive inspection should be done to check the tightness of all screws.
2. In case of production interruption, the main drive and heating will stop. When the power supply is restored, each section of the barrel must be reheated to the specified temperature and kept for a period of time before the extruder can be started.
3. After the extruder is used for 500 hours, there will be iron filings or other impurities from the gears in the reduction box. Therefore, the gears should be cleaned and the reduction box lubricant should be replaced.
4. If the steering of the gauge and pointer is found to be full, check whether the contact of the thermocouple etc. is in good condition.
Daily maintenance of extruder
1. No debris is allowed in the material, and hard objects such as metal and sand are strictly prohibited from entering the hopper and extruder.
2. When opening the barrel cover or the air extraction cover, strictly prevent foreign matter from falling into the host.
3. Sufficient warm-up time is required, and manual cranking should be brisk before driving. Generally, the temperature should be kept constant for 2 hours after reaching the process set temperature.
4. The screw is only allowed to start at low speed, and the idling time does not exceed 3 minutes.

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