Study on the Virtual Measuring System for Machining Accuracy Prediction of Spiral Surface Workpiece
|Course||Mechanical Manufacturing and Automation|
|Keywords||Spiral Surface Workpiece Virtual Measuring System MachiningAccuracy Prediction Random Number Weighting Method|
In modern production, higher and higher processing precision of products isdemand, meanwhile shorter development cycle and lower production cost arerequested, which put forward a pressing need for the virtual measuring technology ofmachining accuracy prediction. Spiral surface parts are important parts widely used inengineering, playing an irreplaceable role in many fields and requiring very highmachining accuracy. But because of the particularity and complexity of spiral surfacemodel, its machining and testing are difficult, and needs repeated trial machining andadjustment to guarantee the machining accuracy, needing long development periodand high production cost. As a result, the virtual measuring system for machiningaccuracy prediction of spiral surface workpiece is put forward and studied in thepaper, aiming at realizing the machining accuracy prediction of spiral surfaceworkpiece, in order to shorten the development cycle, reduce machining costs,improve production efficiency and machining quality.The following several aspects are analyzed in this paper:(1) The current study method and technical difficulties of machining accuracyprediction are analyzed, and a relative easy but high reliable virtual measuringmethod called error loading and measuring of discrete measuring points is presented;Guided by this design principle, the required functions are studied, its overallstructure is built, and specific function modules are divided.(2) The forming principle and mathematical model of spiral surface are analyzed,and connecting with the virtual measuring method above-mentioned, the "revolvingsuperposition method" is proposed and used to construct the spiral surface body. Onthis basis, parameterized modeling of ideal3d model of spiral surface workpiece to bemeasured in virtual measuring system is realized.(3) Various factors that causing machining errors of spiral surface workpiece aredeeply analyzed, considering the errors of machine tool, cutting tool and jig as themain error sources which influence the machining accuracy in different weights; The "Random Number Weighting Method" is proposed to build the mathematical relationmodels between errors and error sources. According to these error models, the errordata are loaded onto the discrete measured points, and the workpiece modelcontaining machining errors is built up.(4) The actual measuring and evaluating methods for machining accuracy of spiralsurface workpiece are analyzed, the characteristic parameters for machining accuracyof spiral surface are studied, and the measuring scheme and error evaluating methodsapplicable to virtual measuring system are determined; Take the characteristics lines(tooth profile line and spiral line) and several important form and position errors ofspiral surface workpiece as the measuring objects to evaluate the machining accuracy,which are virtually measured by the system.(5) Virtual measuring system for machining accuracy prediction of spiral surfaceworkpiece is built, realizing the functions such as parametric modeling, virtualdynamic measurement, machining errors calculation and output. The correspondingexperiments are performed to verify the validity and reliability of the virtualmeasuring system.