What should we pay attention to when making screw?
2018-09-12 10:10:07
How to make good quality screw? What should we pay attention to?
1. extruder screw should be made of alloy steel with small deformation, wear resistance and corrosion resistance. The common materials are 38CrMoAlA alloy steel or 40Cr steel, and the repair parts can also be made of 45 steel.
The 2. screw material blank should be formed by forging.
After machining the 3. screw, the accuracy of the outer circle should reach 8 level (GB180-79).
4. The coaxiality error between the working surface of the screw and the screw thread outer circle at the connecting part of the screw and the transmission shaft should not exceed 0.0lmm.
5. Roughness Ra value of screw thread part working face: the two sides of the screw thread should not be more than 1.6um, the bottom and outer circle of the screw thread should not be more than 0.8um.
6. If the screw is made of low-carbon alloy steel, in order to improve the hardness, corrosion resistance and wear resistance of the thread working face, the surface of the thread should be nitrided. The nitrided layer is 0.3 0.6 mm deep and the surface hardness is 700 840 HV. Brittleness is not greater than grade 2.
The 7. screw inner hole joint should be subjected to 0.3MPa water pressure test. Continuous 5min shall not allow leakage.
