The Optimal Design And Research Of Deep And Small Hole Finishing Electroplating CBN Honing Tools

According to the finishing requirement of length-diameter ratio greater than5and4～20mm in diameter cylindrical hole parts with the mass production of the type, compared with fine boring, lapping, honing, electroplating CBN honing tools was overriding. But with the developmental need of precision parts, the machining accuracy and the surface roughness of inner hole still need to be further improved. The deformation of honing tools which was determined by the structure and machining technology of honing tools was the critical factors of lowering the processing quality of hole. Meanwhile, force calculation was also not explicit formulas, so it was necessary that the structure and machining technology of honing tools were optimized. Being based on the present situation of electroplating technology and the processing theory of general deep hole, the design of electroplating CBN honing tools and the optimization of parameters were researched further. Concrete content as follows:1) The reaming-honing mechanism finishing deep and small hole by using electroplating CBN honing tools and the force of honing tools were analyzed. Compared with reaming, honing and abrasive machining, the process which the grain of electroplating honing tools machininged inner hole contained slippery wipe, plough and scraps form three stages. Honing tools had tangential force, normal force and axial force. The tangential force which was produced by the friction between the rotaion of honing tools and the surface of inner hole was the main cutting force. Because of the fixed shank, honing tools had a pair of couple. The normal force which was the reacting force by the inner hole to honing tools was counteracted. The axial force was produced by the main angle. The axial force must meet with the processing requirement of producing scraps, but the axial force caused the deformation of honing tools, which affected the processing quality of the inner hole. So the numerical optimization of the axial force for honing tools was a good way of improving machining accuracy and surface quality.2) The axial force calculation formula of electroplating CBN honing tools was derived and the influence of the main angle, the feed rate and the mechanical allowance to the axial force was analyzed. According to the good-performance of electroplating CBN honing tools being manufactured by the inside electroplating and the calcutional theory of deep-hole machining tool, the shape and arrange of CBN grains were simplified rationally, thereout, the axial force calculation formula was derived. The size of the main angle for CBN honing tools was the greatest impact for the axial force, the axial force was increasing with the main angle, meanwhile, the axial force was also increasing with the increase of the feed rate and the mechanical allowance, which were found by the mathematical analysis.3) The mathematical model of optimal design was established. The design variables contained the main angle, the feed rate and the machining allowance. The objective function was that the axial force was given the minimum value. It had all kinds of the constraint conditions. The optimal values of the design variables were solved by using MATLAB so that the axial force was reduced as soon as possiable. Finally the physical dimensions of electroplating CBN honing tools being applied in the machining requirements of deep and small hole of guide bar were identified.4) Using the controlled variable method, the optimal result was analyzed in the form of three-dimensional graphics by using MATLAB. When the three feed rate0.7mm/r,1.2mm/r,1.5mm/r were chose respectively, the distributed situation of the axial force and the contact stress with the change of the main angle, the machining allowance was researched. The reduction of the main angle made the axial smaller, so the deformation of honing tools was descreased. The increase of the feed rate made the minimum value of the axial force smaller, meanwhile, the production efficiency was upper. Because the value of the machining allowance was very small, its influence was tiny. In conclusion, the main angle was reduced and the feed rate was increased as soon as possible in order to reduce the axial force under constraint conditions being meet, which is benefic for honing.