What are the technical requirements for screw quality?

The technical requirements for screw quality are as follows: 7 aspects.

The screw is made of 38crmoala, 40cr or 45 steel.

The blank of the screw should be forged.

After rough machining, the screw should be quenched and tempered, and the hardness HB=260 290.

The rough mallet degree of the screw thread part is 100 million value: the two sides of the thread are not larger, and the bottom and outer circle of the thread groove are not larger.

The surface of the thread is nitrided, and the depth hardness of the nitriding layer is HV=700 8400, and the brittleness of the screw is not greater than grade 2. Hope.

Screw: A cylinder with a spiral groove cut on the outer surface or a cone with a spiral groove with a conical surface.

Yongkang City encourages the quality and technical requirements of the screw of the standard parts factory as follows:

1. High temperature resistance, no deformation at high temperature.

2. Wear-resistant and long service life.

3. Corrosion-resistant, the material is corrosive.

4. High strength, can withstand large torque and high speed.

5. It has good cutting performance.

6. The residual stress after heat treatment is small, and the thermal deformation is small.

Extended Information: Precautions for Screw Maintenance:

1. When the screw does not reach the pre-set temperature, do not start the machine.

2. Prevent metal fragments and debris from falling into the hopper, if the first material is processed, a magnetic hopper needs to be added to prevent iron filings from entering the barrel.

3. When using anti-salivation, make sure that the plastic in the barrel is completely melted, so as to avoid damage to the transmission system parts when the screw retreats.

4. When using new plastics, the remaining materials of the screw should be cleaned.

5. When the temperature of the molten plastic is normal but the molten plastic is constantly found to have black spots or discoloration, the glue snail should be checked.

6. During processing, try to make the material plasticized evenly, do not let the metal foreign matter mix into the material, and reduce the rotating torque of the screw.

(1) Technical requirements for barrel quality. The barrel should be made of corrosion-resistant, wear-resistant alloy steel. At present, 38crmoak40cr or 45 steel is mostly used in China.

The barrel blank should be forged. After rough machining, the barrel should be quenched and tempered, and the hardness (HB) = 260-290. After the barrel is machined, the wall thickness should be uniform, and the machining accuracy of the inner hole should meet the grade 7 accuracy in the GB1184-1996 standard.

The surface of the inner hole should be nitrided, and the depth of the nitriding layer should be within the range. Surface hardness 950HV. The roughness of the inner hole surface after finishing should not be greater than.

2) Technical requirements for screw quality. The screw blank is forged with 38crmoal or 40cr alloy steel.

Seven requirements for screw manufacturing quality.

The extruder screw should be made of alloy steel with low thermal deformation, wear resistance and corrosion resistance. The commonly used material is 38crmoala alloy steel or 40cr steel, and the repair parts can also be made of 45 steel.

The blank of the screw material should be formed by the forging method.

After the screw is machined, the cylindrical accuracy should meet the quality requirements of grade 8 (GB180-79).

The coaxiality error of the working shaft surface on the screw and the connection part of the transmission shaft and the thread outer circle of the screw should not be greater than.

The roughness of the working surface of the threaded part of the screw is not greater than the two sides of the thread, and the bottom and outer circle of the thread should not be greater. Hua Hong answered.

If the screw is made of low-carbon alloy steel, in order to improve the hardness and corrosion resistance and wear resistance of the thread working surface, the thread surface should be nitrided, the nitriding layer is deep, and the surface hardness is 700 840HV. Brittleness is not greater than grade 2.

From the extrusion process, it can be seen that the screw works under high temperature, certain corrosion, strong wear, and high torque, therefore, the screw must:

1. High temperature resistance, no deformation at high temperature.

2. Wear-resistant and long service life.

3. Corrosion-resistant, the material is corrosive.

4. High strength, can withstand large torque and high speed.

5. It has good cutting performance.

6. The residual stress after heat treatment is small, and the thermal deformation is small.