Patent ID: 11860078
Assignee: NORTHWESTERN UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC B  G | IPC B  G

Claim 2:
3. A control method of an experimental device for SDC (stochastic distribution control) of powder particle sizes in a disc mill system, comprising the following steps:
step 1, performing an initial setting:
according to a production efficiency of the disc mill system, setting a target PDF (probability density function) shaping of a distribution of the powder particle sizes, an initial value of a screw feeding amount, a starting time and a stopping time of a second DC motor in a sampling device, an initial value of a mill disc gap and an initial value of a mill speed through a system of an upper computer and receiving set values of the screw feeding amount, the mill speed and the mill disc gap which are obtained by adopting a SDC algorithm of the upper computer;
wherein the starting time and the stopping time of the second DC motor in the sampling device are set according to a detection time required by a laser particle analyzer;
the initial value of the mill speed is set according to actual material hardness and the production efficiency of the disc mill system;
a control flow process of the screw feeding amount lies in that a screw speed is adjusted according to the screw feeding amount measured by an electronic scale, so that quantitative feeding of a screw feeding control device is achieved, the screw feeding control device is used for controlling the screw feeding amount according to the screw speed of a screw feeder, and the screw feeding amount is set by the upper computer, so that quantitative feeding of the disc mill system is achieved, and then a material is conveyed into a mill area of the disc mill system;
a control flow process of the mill speed lies in that the mill speed of the disc mill system is controlled by adjusting frequency of a frequency converter with a mill speed adjustment device until the mill speed reaches the set mill speed;
a control flow process of the mill disc gap lies in that the system of the upper computer is used for controlling a rotating speed of an AC servo motor to drive a movable mill disc to move horizontally; a position of a fixed mill disc is taken as a zero position; a moving speed is adjusted by a speed reducer in a moving process; a displacement sensor is used for acquiring a position signal of the movable mill disc in real time and feeding back the position signal to the system of the upper computer for calculating a mill disc gap; through comparison of the position signal with the set mill disc gap, whether the movable mill disc reaches a specified position is judged, and a mill disc gap servo control device is controlled for correspondingly adjusting a position of the movable mill disc according to a calculation result, so that the mill disc gap between the movable mill disc and the fixed mill disc can reach the set mill disc gap, a displacement of the movable mill disc is accurately positioned, and the mill disc gap is controlled by accurately positioning the movable mill disc;
step 2, starting the disc mill system;
step 3, performing sampling through the disc mill system according to the starting time and the stopping time of the second DC motor in the sampling device;
wherein a control flow process of the sampling device lies in that the second DC motor is started for sampling when the starting time reaches the set starting time of the second DC motor, and when the second DC motor in the sampling device is in a starting state, powder is sampled, a sampling amount of the powder is controlled according to a length of the starting time of the second DC motor, and powder is conveyed into the laser particle analyzer through a sampling casing pipe; the second DC motor is stopped when the stopping time reaches the set stopping time of the second DC motor, when the second DC motor in the sampling device is in a stopping state, the produced powder enters a powder recovery tank, so that intermittent sampling is achieved; the sampling amount in every detection period is the same, and the sampling amount is judged by adjusting the length of the starting time of the second DC motor in the sampling device;
step 4, acquiring an actual PDF shaping of the distribution of the powder particle sizes and feeding back the actual PDF shaping to the upper computer through the laser particle analyzer; and
step 5, updating the set values of the screw feeding amount, the mill disc gap and the mill speed with a SDC algorithm according to the actual PDF shaping of the distribution of the powder particle sizes, detected by the laser particle analyzer, and the set target PDF shaping of the distribution of the powder particle sizes if the actual PDF shaping of the distribution of the powder particle sizes is inconsistent with the set target PDF shaping of the distribution of the powder particle sizes; otherwise, ending the control flow process if the actual PDF shaping of the distribution of the powder particle sizes meets production requirements; a user can query a curve of the actual PDF shaping of the distribution of the powder particle sizes, which is detected by the laser particle analyzer, through the upper computer.