Particle size distribution control in disc milling system based stochastic distribution control experimental device and method

An experimental device for SDC (stochastic distribution control) of powder particle sizes in a disc mill system, adopting the disc mill system, and comprising:

• a screw feeding control device, a mill speed adjustment device, a mill disc gap servo control device, a sampling device, a laser particle analyzer, a control cabinet and an upper computer;
• wherein the disc mill system is a vertical double-disc powder mill and comprises a movable mill disc and a corresponding fixed mill disc;
• wherein the screw feeding control device comprises a screw feeder, a first DC (direct current) motor and an electronic scale;
• wherein the screw feeder is connected with the first DC motor, and the electronic scale is connected with the upper computer and is used for measuring a screw feeding amount;
• wherein the mill speed adjustment device comprises a frequency converter and a three-phase asynchronous motor;
• wherein the three-phase asynchronous motor is connected with the movable mill disc of the disc mill system;
• after a material enters a mill area, the movable mill disc is driven by the three-phase asynchronous motor to rotate;
• and the frequency converter is mounted in the control cabinet;
• wherein the mill disc gap servo control device comprises an AC (alternating current) servo motor, a speed reducer and a displacement sensor;
• wherein the AC servo motor is connected with the speed reducer, the speed reducer is connected with the movable mill disc of the disc mill system, and the displacement sensor is mounted on a driving shaft connected with the movable mill disc in the disc mill system and is connected with the upper computer;
• wherein the sampling device comprises a second DC motor, a sampling casing pipe and a powder recovery tank;
• wherein the sampling casing pipe is connected with a powder outlet of the disc mill system and the powder recovery tank respectively;
• wherein according to a detection period of the laser particle analyzer, a starting time and a stopping time of the second DC motor are set;
• wherein a PLC (programmable logic controller) is arranged in the control cabinet, the PLC is connected with the first DC motor of the screw feeding control device, the second DC motor of the sampling device and the AC servo motor of the mill disc gap servo control device respectively, and the frequency converter is connected with the three-phase asynchronous motor of the mill speed adjustment device;
• wherein the PLC and the frequency converter are both connected with the upper computer and are used for receiving an instruction sent by the upper computer;
• wherein the screw feeding control device is used for controlling the screw feeding amount according to a screw speed of the screw feeder, and the screw feeding amount is set by the upper computer, so that quantitative feeding of the disc mill system is achieved;
• wherein the mill speed adjustment device is used for controlling a mill speed by adjusting frequency of the frequency converter;
• wherein the disc gap servo control device is used for driving the movable mill disc to move horizontally, a position of the fixed mill disc is taken as a zero position, and the displacement sensor is used for acquiring a position signal of the movable mill disc in real time, feeding back the position signal to a system of the upper computer for calculating a mill disc gap and driving the movable mill disc to adjust a position according to a calculation result, so that a displacement of the movable mill disc is accurately positioned, and the mill disc gap is controlled by accurately positioning the movable mill disc;
• wherein 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 the powder is conveyed into the laser particle analyzer through the sampling casing pipe;
• when the second DC motor in the sampling device is in a stopping state, the produced powder enters the powder recovery tank, and intermittent sampling is achieved;
• the sampling amount in every detection period is the same, and the sampling amount is adjusted by controlling the length of the starting time of the second DC motor in the sampling device;
• wherein the upper computer comprises a SDC algorithm;
• the upper computer is used for setting initial values of the screw feeding amount, the mill speed, the mill disc gap, a target PDF (probability density function) shaping of a distribution of powder particle sizes as well as the starting time and the stopping time of the second DC motor in the sampling device and receiving set values of the screw feeding amount, the mill speed and the mill disc gap which are obtained by adopting the SDC algorithm;
• wherein the set values of the screw feeding amount, the mill speed and the mill disc gap are updated by adopting the SDC algorithm according to an actual PDF shaping of the distribution of the powder particle sizes and the set target PDF shaping of the distribution of the powder particle sizes;
• wherein the screw feeding amount is controlled by controlling the screw speed in the screw feeding control device;
• wherein the mill speed is controlled by adjusting the frequency of the frequency converter;
• wherein the movable mill disc is driven by the AC servo motor to move, and the mill disc gap is controlled by accurately positioning the movable mill disc;
• and
• wherein the updated set values of the screw feeding amount, the mill speed and the mill disc gap are calculated by adopting the 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;
• 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.