Theoretical Research On Model&Methods Of Deep-hole Straightness Detection

The straightness error of axis in deep hole processing is a common phenomenon duo tothe tool deviation because of the processing complexity itself, its large length and smallaperture also makes it a technical problem to detect straightness error. For some disadvantagesof low detection accuracy, space limitations or high cost, the commonly-used methods can notfully meet high-tech industries requirement of high detection accuracy, such as aerospace andautomotive engine manufacturing industry. Therefore, the study on deep hole axis straightnesserror detection is launched in this paper.In this paper, the mechanism of hole axis deviations is analyzed to state the complexityof controlling its machining process from the aspect of processing method, the assemblyprecision of guide sleeve, the space between guide sleeve-drilling bit, etc. Then, a new deephole axis straightness error detection model related to "the hole axis micro-element vector"and its expression are proposed based on the traditional error detection model, with curvecharacteristics being dynamically analyzed by introducing curve-frame according todifferential geometry. The new model demonstrates that three relationships exist between thepractical and ideal element of hole axis including intersect, parallel and bifacial. Furthermore,the introduction of “micro-corner amount” makes up the shortcoming of traditional modelwhich only considered the “micro-translation amount” between practical and ideal axiselement, so it makes deep hole axis straightness detection more comprehensive. Finally,different detection methods are studied based on these two models. Two correspondingdevices are designed, and their principles and algorithms to detect micro-translation ormicro-corner amount are analyzed. The vibration characteristics and adaptability are analyzedby splitting their simplified-model, displacement–response curve base on Matlab areachieved，which shows that hole wall influence on core-component of the two systems arerespectively in-0.1mm~0.1mm and (0-6)×10-5mm, indicating that two influences are verysmall and the latter is more stable and reliable than the former. For the use of optoelectroniccomponents such as parallel light, four-quadrant detector, laser probes or grating anglesensors, they are adaptive to deep hole and can detect deviation dynamically without anydestruction in the whole process, reflecting the level of deep hole axis straightness directly.