Study On Assembly Parts Of Tool And Boring Bar Dynamics Of BTA Deep Hole Processing System

Chipping, tool wear and non-stable motion of boring bar always occur in the processof BTA (Boring and Trepanning Association) deep hole boring, which are the mainabnormal cutting conditions that damage the quality of wokepiece. In order to solvethese problems, the dynamics and motion characteristics of boring bar were studiedconsidering the structural factors and external factors in the system of BTA deep holeboring. Based on the review literature and practical work in hydraulic componentfactory, the research work was carried out by combining theoretical analysis, numericalsimulation and experimental verification. The research work was helpful for quality ofwokepiece and improving tool life and optimization on system of BTA deep holeboring.Taking the typical assembly parts of boring bar and tool as a research object, theresearch work includes following aspects:Firstly, based on the theory of Systems Dynamics, the stability conditions of boringbar with vortex motion were studied considering disturbance of cutting fluid and itscauses and mechanics were analysised. Then, some typical tracks of boring bar withvortex motion were simulated under certain conditions according to the research results.By taking it as simply supported beam, simulate dynamics of boring bar with severaloperating speed considering the affects of cutting fluid, average clearance and otherfactors.Secondly, a model was established to calculate the maximum bending stress andshearing stress of boring bar considering different working states, such as includinginternal and external cutting fluid vortex, linear crack of the across-section of boring bar.Then a new fatigue strength criterion was deduced based on bending-torsioncombination alternating stress fatigue strength theory.Thirdly, combining the practical production of heavy hydro-cylinder, the influence ofvortex motion and other factors of boring bar to the tool life were analysised. And someeffective measures were proposed for improving the tool life in the deep hole boring.At last, to give full play the self-piloting, guiding, balancing the cutting force andburnishing action of guide pad, a new kind of guide pad made of ductile cast iron with good energy dissipation was developed. Wear properties of JIS-FCD/FCAD cast ironswere studied.Innovations of this thesis as follows: In order to make full use of guide pad made ofductile cast iron with antifriction and good energy dissipation, sliding wear test of eightkinds of cast ductile iron were carried out. That brings a new idea for improving thestability of system of deep hole processing.