Envelope Processing Of Double - Milling CNC Screw Milling Machine And Optimization Of LABVIEW Program

As the core component of the injection molding process, screw is difficult to be processed owing to Diversity and complexity of the shape. Because the traditional forming method has the defects of low machining accuracy and low machining efficiency in the processing of complex screw with variable pitch, variable bottom diameter, variable spiral angle and so on, enveloping machining technology is put forward. First of all, the thesis analyses influence on the whole screw process after installing double milling head from the mechanical structure of the double milling head CNC screw milling machine. After finding respective movement characteristics of five axis on milling machine, the main drive shaft was identified as axis of motion control parameters. Followed by analysis of the milling machine processing object, the paper analyzed the principle and parameters of screw extrusion, and determined the machining process of the envelope method. For screw with variable pitch and variable depth, uniformly accelerated spiral line was selected as its mathematical model, the theoretical calculation and machining examples verified the uniformly accelerated spiral pitch value is better than polynomial spiral line and variable spiral line. The experimental results show that pitch value of the uniformly accelerated spiral thread in the overall distribution is more stable, and machining error value of length is less than polynomial helix and variable helix. According to the meshing principle of tool spiral surface and screw surface, mathematical model of the envelope spiral surface was constructed, and the method of screw machining was realized by LABVIEW programming. In order to evaluate the helix error value of envelopment, the paper used method of the screw machining simulation to obtain coordinate data of the workpiece spiral surface, compared with coordinate data of theoretical spiral line, obtained error value of machining simulation less than 0.1mm.Finally, through the optimization of human-machine interface and increasing the control function, the paper realized the optimization of LabVIEW program, which increased operability of the CNC system. According to the milling machine processing condition registration form in the 4 months, the result showed that: the optimized NC program greatly reduced faulty operation rate, time-consuming operation from the original 260 minutes reduced to 80 minutes in 4 months, which greatly improved the processing efficiency.The difficulty of envelope processing in NC screw milling machine with double milling cutter is according to the change of the spatial position of the cutting point, to build a helical enveloping surface equation, which also contains simplification of the cutter model and establishment of cutter contour shape equation and deduction of spiral line with variable pitch equations. How to evaluate the error of spiral line is one of the difficult points. Through SOLIDWORKS secondary development, the simulation process of the screw is realized, and the error between the spiral line of simulation and the spiral line of theory is obtained. According to the parameters of the envelope spiral surface equation, the corresponding relationship between the different axes of the NC milling machine is found, and the LABVIEW language is programmed into the data center to realize the control of the five axes.