Working principle and operation method of screw discharge sigma blade kneader mixer

Working principle and operation method of screw discharge sigma blade kneader mixer

The screw extrusion kneading machine is a high viscosity material processing equipment that integrates mixing kneading and screw extrusion discharging functions, widely used in industries such as chemical, plastic, rubber, food, and medicine. Its core lies in achieving efficient mixing through a differential rotating stirring blade, and utilizing a screw structure to achieve continuous and stable discharge.

working principle

Mixed stage:

The motor drives the reducer to drive the active paddle, and then drives the driven paddle through the gear. Two mixing paddles (usually Z-shaped, ∑ - shaped, or helical blades) rotate in opposite directions at different speeds (such as 42 r/min and 28 r/min), generating strong axial and radial shear forces in the cylinder, causing the material to repeatedly flip, knead, and mix, achieving uniform mixing.

Discharge stage:

After mixing is completed, the material is pushed axially by a propeller blade or specialized screw structure, and continuously extruded into shape through the die of the machine head. This method is suitable for scenarios that require continuous discharge, molding, or avoid manual flipping of the cylinder, especially for materials with high viscosity, heat sensitivity, or requiring sealed operations.

Auxiliary functions (depending on the model):

Can be equipped with a vacuum system (vacuum degree up to -0.096 MPa) for removing bubbles.

Adopting a jacket heating/cooling system, it supports electric heating, steam, thermal oil or water cooling, achieving precise temperature control.

The cylinder body and blades are mostly made of SUS304/316L stainless steel to ensure corrosion resistance and hygiene requirements.

Operation Method

Preparation before operation

Remove dirt from the mixing tank, remove rust proof grease, and check whether the lubrication points (reducer, running gear, bearings, etc.) are filled with suitable lubricating oil (such as 46 # mechanical oil or high-temperature resistant lithium grease).

Check whether the circuits, pipelines (steam/cooling water), and fasteners are normal, and confirm that the safety devices are effective.

Trial operation

Run without load for 20-30 minutes and observe for any abnormal noise, vibration, or leakage in the transmission system.

If it is a vacuum or heating type, it is necessary to separately test whether the temperature control and vacuum system meet the standards.

Feeding and mixing

Add materials in the process sequence, start the mixing system, set the speed, temperature, and time (some models support PLC automatic control).

Attention should be paid to avoiding overloading for high viscosity materials, and batch feeding should be carried out when necessary.

Discharge material

After mixing is completed, the screw discharge system is started, and the material is continuously extruded through the mouth mold, which can be directly collected or enter the next process (such as granulation and molding).

The discharge speed can be adjusted through a frequency converter to match the production rhythm.

Shutdown and Cleaning

After shutdown, clear the remaining materials and clean the cylinder body and screw in a timely manner (some models support quick disassembly blade structure for easy maintenance).

Regularly check the clearance between the blades (usually 3-5 mm) and the wear of the shaft seal, and replace them in a timely manner.

Precautions

Lubrication maintenance: Change the oil of the reducer every 1500 hours; Add high-temperature resistant lithium grease to the bearings every month (once every half month in summer).

Safe operation: It is strictly prohibited to idle the screw for a long time without any materials to avoid wear and tear.

Applicable materials: Especially suitable for high viscosity and elastoplastic materials such as silicone, hot melt adhesive, battery slurry, high filling plastics, food adhesive base, etc.