The Study And Production On The Machining Center Spindle Unit Of BT40 Type High Speed,High Precision Direct Coupling

The manufacturing industry is the pillar industry of a nation's economy,and it's one of the factors which reflect a nation's comprehensive strength.The foundation of the manufacturing industry is the machine tool.High-precision and high efficiency machine tool is the guarantee of the product's quality,and the machine tool integrating accuracy and efficiency is machining center.The machine tool's main component is the spindle unit which clamps the workpiece or the tool and rotates when the machine tool works,so the precision of the spindle unit has an important influence on the precision of the machine tool.The spindle unit of the machining center is a functional device which has loose broach agencies,driven by servo motor,has high speed,high rigidity and high precision,and it has an important influence on the quality and productivity of the machining center.According to the actual engineering demand of the market for high speed,high precision machining center spindle unit,a set of high speed,high precision,direct-coupling mechanical spindle unit is developed through comparative analysis and theoretical calculation in this paper and it has an important significance to the machining center of our country.The main content of this paper is as follow:In order to meet the engineering requirements,the design requirements of the spindle unit are put forward,and the overall design scheme of the spindle unit is demonstrated.Through the demonstration,the mechanical spindle unit,direct connection structure,BT40 tool holder and loose knife program are determined.The bearings are selected of P2-angle contact with ceramic ball bearings,two series,the overall anti-loaded 4-row rolling bearing combination structure,light preload,grease lubrication.The circulating water cooling method is designed for the spindle unit sleeve.The main parameters of the shaft structure are designed and calculated.According to the determined rolling bearing combination structure,the optimal bearing span and the radial stiffness of the spindle are designed and calculated.The radial runout of the spindle cone hole,the radial runout of the centering journal,the axial movement precision of the spindle and the front and rear gripping are calculated.The size and the number of the disc spring,the knife stroke and the knife force were calculated,and the disc spring type and quantity are determined by the software prepared by the Mubea company.The manufacturing process of the main parts of the spindle unit is compiled,and the difficulties encountered in the processing of the parts are demonstrated in detail.The specific technological measures are put forward.According to the results of the precision measurement of the main parts,the assembly process of the spindle unit is compiled,and the length of the spacer is adjusted in the process of assembling.The spindle unit is obtained according to the stiffness requirement.The geometric accuracy and comprehensive detection of the spindle unit assembled are tested,including the runout of the spindle taper hole,near the spindle and at the 300 mm,the spindle's axial interpolation,temperature rise test,vibration test,noise test,static stiffness test,broach experiments,the spindle's axial error motion detection,radial motion detection and tilting motion error detection.After testing,the theory of design data and the difference of the actual product are found,the rule is groped and provides the basis for future design.