The Experimental Research For Deformation Precision Compensation Of RAM For TK6920b Cnc Floor Type Boring And Milling Machine

As the basic equipment of the industrial manufacture the CNC floor type boringand milling machine plays an irreplaceable character in the mechanical processingsuch as in energy metallurgy，source， mine，power generate，motorcar and nationaldefense equipments，aerospace and so on，and it is also the key equipment of the bodyparts processing。The spindle of CNC floor type boring and milling machine moves in the ram，during the processing the length of the ram out of the spindle box is usually about1200mm or so while the weight is about5tons，therefore the ram will cause theserious deformation in the action of its own high weight and the boring force，that ismuch larger than the national standard accuracy0.03mm/500mm and the phenomenonis what we often say the“spindle bending”，The ram accuracy is the key accuracy ofCNC machine tool，which influenced the whole accuracy level of machine tools。The“spindle bending” will cause the great influence to the machinery processingprecision in industrial production so that t he product processing quality can’t beguaranteed，which restricts the developmental level of the manufacturing industry。Concerning the “spindle bending” phenomenon existing in CNC floor typemilling and boring machine，analysis to its solution has been carried out in thisarticle，and advantages and disadvantages are listed。The solution of oil pressurecylinder-draw bar and Pre-stress force deflection machining method which carry outcompensation to “spindle bending” is proposed。 The author of this article hasalready been verified by testing on TK6920B CNC floor type milling and boringmachine which was manufactured by Wuhan Heavy Duty Machine Tool GroupCorporation for a domestic customer。This paper studied the specific contents as the following:1．According to the construction of the TK6920B CNC floor type boring andmilling machine tool and combination with the knowledge of mechanics material；Thedeformation of the spindle ram was also analyzed with the theoretical calculation。2．The combination to the attribute and the correlated construction of the spindleram。Analyze the influence factor of the spindle ram precision。3．According to the theoretical deformation analyzed calculation and the maininfluence factor of the spindle ram precision；Pre-stress force deflection machining method is adopted to eliminate the deflection deformation result from the weight ofram and design the oil pressure cylinder-draw bar，proofing the feasibility of theprecept on the basis of experiment。Result：the largest deformation of the ram of the TK6920B CNC floor typeboring and milling machine tool was about0.052mm which was caused by its ownhigh weight and the boring force；By adopting Pre-stress force deflection machiningmethod and “oil pressure cylinder-draw bar” mechanism for compensation，thedistortion is reduced to0.012mm/500mm and0.02mm/1200mm，which meet nationalstandard and user’s higher requirement to accuracy。It is the ideal solution for thetechnical difficulty of “spindle bending”。...