Research On Embedded Control System Of Boiling Powder Feeder

Laser additive manufacturing(LAM)is a new type of manufacturing technique,which can effectively increase the comprehensive performance of raw material.Powder feeder as one of the most important part of LAM equipment system,the accuracy and uniformity of powder feeding rate may have a great impact on remanufacturing layer quality.In this paper,a new kind of boiling powder feeder and embedded C losed Loop Control System was self-designed according to the manufacturing process requirements as well as its development situation domestic and abroad.Firstly,powder feeder core was designed in modules.And then,the gas path loop of the powder feeder was designed after structure size optimization.Meanwhile,the main control parameters and auxiliary parameters to control the feed rate was determined by comparing the influence of boiling gas,transmission gas and overflow gas etc.on the powder feeding speed.Finally,the comparison experiment showed that adding electromagnetic proportional valve could improve the control parameters of the control accuracy.Depend on experimental conclusions,we design dsPIC digital signal processor as the core of embedded control system.According to control scheme,we design the hardware circuit of the system: including main control board module,linear power module,display module,data collection module,anti-interference module.Then,I design the corresponding software program on the basis of hardware : signal acquisition procedures,remove excess weight procedures,filtering procedure,analog to digital conversion procedures,PID closed-loop control procedures.After the end of the control system hardware and software debugging,in order to assist slave computer adjust the PID parameters,which can be clearly observe the actual rate of curve variation of the actual feed rate curve,take advantage of PC calculate ability,high speed,good display interface,designing host computer based on virtual instrument LabVIEW,getting the best PID parameter value.I obtained the running error by means of stability experiment,the relative error between the feed rate of 0-50 g / min was controlled within 2.5%,which meet the demand of stable feeding,high precision,wide range of adjusting feeding speed;in order to further verify the advantages of the closed-loop powder feeding,original powder feeder is compared with the sign of the powder feeder by laser cladding experiment.The experimental results show the advantages of the closed-loop boiling powder feeder,which also has a good practical value in the field of laser material manufacturing.