The Research On The Spindle Ram Deformation Analysis And Error Compensation Technology Of The Large NC Floor Type Boring And Milling Machine

As the basic equipment of the industrial manufacture the large numerical controlfloor type boring and milling machine plays an irreplaceable character in themechanical processing such as in energy source, metallurgy, mine, aerospace, motorcar,power generate and national defense equipments and so on, and it is also the keyequipment of the body parts processing.The spindle of large NC 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 about1200mmor 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 down” which will cause the great influence to themachinery processing precision in industrial production so that the product processingquality can’t be guaranteed.In this paper, the spindle ram finite element model of the TH6920large NC floortype boring and milling machine was established, and then the deformation was alsoanalyzed with the method of the theory calculation combined with the finite elementsimulation, meanwhile we the corresponding compensation device was designed toreduce the deformation so that the machining accuracy could be improved.This paper studied the specific contents as the following:1. With the reference of the existing spindle ram mathematical model and thecombination to the actual situation of the TH6920large NC floor type boring andmilling machine, the equivalent model parameters of the spindle ram was fixed on andthe deformation was also analyzed with the theoretical calculation.2. After the spindle ram model has been confirmed, the main stress anddeformation of the spindle ram was analyzed by using of ANSYS software to establish its finite element model according to the elastic-plastic mechanics material, mechanicsand the finite element theory.3. Based on the theory of the spindle ram deformation analysis, the "hydrauliccylinder-bars" compensation device was designed, meanwhile this model was importedinto the finite element software ANSYS for the deformation compensation effectanalysis compared with the original one, so that the correctness of the compensationmodel could be verified.4. Based on the compensated spindle ram model, the modal analysis was carriedout by using the finite element software ANSYS and the vibration frequency range ofthe spindle ram was obtained, and then these frequency ranges could be avoided toreduce its vibration in the operation, so that the machining precision of the wholemachine could be further improved.5. PLC was chosen as the program controller and feedback control equipment, theelectro-hydraulic servo proportional valve as the compensation tension control valve,besides, control procedures of the spindle ram working stroke to the correspondingelectro-hydraulic servo proportional valve compensation tension were given for theelectrical PLC feedback control of the compensated spindle ram system.The results showed that: the largest deformation of the ram of the large numericalcontrol floor type boring and milling machine was about0.061mmwhich was causedby its own high weight and the boring force, however, after compensated with the"hydraulic cylinder-bars" compensation device the deformation was reduced to0.025mmwhich was up to the national standard accuracy and also verify thereliability of the finite element simulation.