How to make a good quality extruder screw? What should we pay attention to?
ⅰ. The extruder screw should be made of alloy steel with small deformation when heated, wear resistance and corrosion resistance. Commonly used materials are 38CrMoAlA alloy steel or 40Cr steel, repair parts can also be made of 45 steel.
ⅱ. The extruder screw material blank should be formed by forging method.
ⅲ. After machining, the outer circle precision of the extruder screw should reach grade 8 (GB 18 - 79) precision quality requirements.
ⅳ. The coaxiality of the thread outer circle between the working shaft surface of the extruder screw and the connecting part of the drive shaft and the screw should not be bigger than 0.01mm.
ⅴ. The screw part of the extruder screw surface roughness Ra value: the two sides of the thread should not be more than 1.6um, and the thread bottom and outer circle should not be more than 0.8um.
ⅵ. If the low carbon alloy steel material is used to manufacture the extruder screw, in order to improve the hardness, corrosion resistance and wear resistance of the thread working face, the surface of the thread should be nitriding, the depth of the nitriding layer is 0.3 ~ 0.6mm, and the surface hardness is 700 ~ 840HV. Brittleness is not greater than grade 2.
ⅶ. The inner hole of the extruder screw shall be tested by 0.3mpa hydraulic pressure, and the water leakage shall not be allowed for 5min.
If the extruder screw can not be removed, there are usually the following reasons:
ⅰ. If it is not stuck, but because the material is not clean and solidified, the heating ring of the barrel can be kept warm for a period of time and then looked at the top.
ⅱ. If it does not work, you can disassemble the bolts between the reducer and the barrel, and separate the barrel and the extruder screw from the reducer. Add a welding seat to the barrel, and then use the hydraulic jack to help.
ⅲ. If it does not work, it can only find the extruder screw manufacturer. They will put the extruder screw barrel in the nitriding furnace to burn, burn the raw materials inside at high temperature, and the extruder screw can come out.
ⅳ. If it is in a hard object stuck the extruder screw, and after the third method it can't separate. And then it can declare to replace the extruder screw barrel, because in this case even forcing the screw out, the painfully extruder screw barrel will be as a result of the movement of hard and cause damage on the surface, it will affect the future production.