Do You Know the Metering Principle of Auger Type Powder Filling Machine?
I. Principle of Auger Metering and Filling System
Structure:
The auger metering filling system mainly consists of Drive Motors, Hopper, Blenders, Auger, and Auger Funnel (Tube).
The rotary fill of the auger is powered by a servo motor or stepper motor, and the power is transmitted between the two by synchronous. So that the number of revolutions of the auger can be accurately controlled, thereby improving the accuracy of the fill.
The control signal of the number of revolutions of the auger is calculated by the PLC program controller or SMC (single chip microcomputer) according to the set weight value, and the corresponding volume is calculated according to the density. After calculation, the corresponding control pulse signal is output to the driver motor (servo motor or stepper motor), and then servo motor rotates the corresponding number of turns according to the input pulse signal. And the synchronous stick drives the auger to rotate to complete each metering and filling process.
In this process, the main factor affecting the fill amount is that the stirring motor continuously working when the material loading to hopper by the conveyor. The driver motor waits for the fill signal to arrive, starts the driver motor auger rotation and ends the fill, weighs the feedback and calculates the next rotation angle of auger.
II. Simulation Results
- 2.1 Velocity and Pressure Fields in The Auger Groove
Through the velocity pattern of the individual material powders, the direction of the velocity of the material during the rotation of the auger can be clearly seen, which is not consistent with the velocity map of the material powders previously obtained through a purely mathematical model, which indicates that the material particles are in the process of rotation.This shows the complexity of the movement process of the materials during the rotation process. There are limitations only through mathematical analysis. Experience is also indispensable for the control of materials. - 2.2 The Effect of Auger Rotating Speed on The Filling Amount
It is generally understood that the higher the auger rotating speed with the greater the filling amount. When the auger rotates at high speed, the density between the materials decreases with the increase of the shear rate. The metering accurate of the material is difficult to control, so the filling amount and the auger rotating speed are not absolutely linear. - 2.3 Optimization of Auger Parameters
In actual production, the main parameters of the design auger are auger thread distance, auger thread angle, and auger thread depth (auger diameter).The auger thread distance will be pre-set according to the actual fill amount, and the main parameter affecting the auger measurement efficiency is the auger thread angle. Because the material moves downward under the forced action of the auger thread surface, the larger auger angle of the auger thread, the material fill speed larger, and the filling efficiency of the auger is correspondingly increased, but the auger thread angle cannot be increased without limit. By simulation, when the auger thread distance and the g thread depth (auger diameter) are constant, the auger thread with different angles get a better angle range of 16-25 degrees.
However, in the specific practical application, according to the different characteristics of the powders, the three parameters should be adjusted accordingly. First, one or two parameters are determined, and the other parameters are optimized to achieve the best measurement effect.
III. Conclusion
- According to the theory of computational fluid mechanics, it provides a new method for the design of powder metering auger, but it has certain limitations.
- The auger rotating speed has a great influence on the filling amount, but it is not a simple linear relationship, which is related to the viscosity of the material particles.
- In the design and use of the auger, the influence of the auger geometry parameters must be comprehensively considered, and the appropriate parameters should be selected according to the filling powder and the filling amount.