Research On Thermal Characteristic About Headstock Of SYSK-209 Pipe Threading Lathe

According to the survey of position of manufacturing field and its demands indevelopment , this paper is targeted at enhancing the machining accuracy of CNCmachine tools , through conducting a thorough study on thermal characteristic andthermal error compensation techniques .The study mainly consists of these followingparts:ONE: IntroductionThe CNC machine tools are mainly used in industry domains , for example :automobile, airplane, electric power, ships, and so on ,providing the foundationequipment for all the various industries. From the 9th China International MachineTools Show (CIMT2005),we know that : the future development tendency of themachine tools industry will be: high speed, high accuracy, high-technique as well asenvironmental protection. High-speed, high-effectivity and the high-accuracy is basicrequest of the 21st century manufacturing industries. With the development of themodern manufacture technology , thermal deformation control in work process hasbecame a key question for increasing precision of the machine tools. Another words:there is no precision without control of thermal deformationThis paper main research content was the structure digitized design about theheadstock of SYSK-209 Pipe Threading Lathe, and simulation analysis of thermalcharacteristic and thermal deformation;obtaining the optimized structure, improvingdesign proposal of this machine tools. Then the study has successfully been used inthe production, has created the economic efficiency for the enterprise.Two: Thermal deformation of Machine toolsThe machine tools thermal transmission is a complex process, according to thephysical essence of heat transfers, the thermal transmission has three essential ways:heat conduction, heat convection and heat radiation.The heat conduction is the process of the quantity of heat transmit through thesolid or the static fluid from the high temperature part to the lower temperaturepart;for example :when the cutting heat passes on by the tool bit to the tool's body.When fluid stream from solid surface, the heat change between the two part is calledthe heat convection. For example , the heat transfer way between the lubricating oilplashed and the box wall surfaces in headstock of the machine tools is primarily heatconvection. The heat radiation is the phenomenon that the objects carries on thethermal transmission through electromagnetic waves ,which have the certainwavelength ranges. For example, when the machine tools working , the quantity ofheat which must be radiated to the workshop ,as well as the radiation from thesunlight and the warmer air in workshop also can cause the temperature of machinetools rise , all these are the heat radiation examples.The working condition of headstock is complex, because its contour is not regularand its shape are respectively different. The heat source of headstock is the bearingand other moving parts ,which pass on the friction heat, moreover, the lubrication oilmist will splash, the flow may passes partial friction heats between the moving partsand the box wall surfaces, which will form additional heat sources. Usually, in theseheat sources, the spindle bearing gives off heat mainly.Three:Modern computer aided design is take the mechanical industry CAD applicationas the core, it is the essential technology of the machine design automation. In thispaper, the headstock of machine tools was modeled by the CAD software-SolidWorks.The main thermal source of headstock in machine tools is the spindle bearings, thethermal which caused from the bearings friction will be influenced by many kinds offactors , except for the type of bearings, the structure feature , the structure size andthe arrangement form, the bearing operating mode condition, for instance the quantityof lubricant, the load form, the rotational speed and so on ,also can affect the thermalof the bearings . If the spindle bearings give off a lot of thermal , it indicate that theenergy consumption of the whole system is bigger, than it would cause there be morethermal deformation ,so the thermal characteristic of the system would be influencedbadly.Machine tools when revolution, the general meeting meets the heat changephenomenon which on the fluid stream machine tools certain wall surface but hasoccurred, this kind of process is called the convection heat transfer, whencounter-flow heat transfer fluid convection and heat conduction two joint action result.Machine tools big-ticket item (lathe bed, column, crossbeam, foundation and so on)always by some levels, vertical either inclines the even wall or the curved surfacecomposition, gets up the convection heat transfer is time the fluid stream these wallsurface counter-flow heat transfer.A reasonable model was put forward to calculate the temperature in this paper,and finite element method is used to calculate the heat-emission, through iterativetechnique the problem that temperature field is unknown within the headstock of themachine tool is solved. In addition, according to various thermal exchange forms,Models of calculation of different border conditions are given.Four: simulation analysis and computation of thermal deformation based on theFEM software--ANSYSThe finite element method(FEM) origins the structure matrix analysis method inthe aeronautical engineering in the 50's. This method needs to solve is the complexrelations between the stress and the displacement. The ANSYS software is alarge-scale general CAE software , which takes the finite element analysis as thefoundation, obtaining approval of the global industry . And its user group distributeseach place in world. It has formidable and the widespread analysis function, and theintegrated processing technology as well as the sufficient product series and the opensystem.The goal of ANSYS thermal analysis is calculates the temperature field of themachine tools headstock. Carrying on the state analysis with the third kind ofboundary condition model, every node temperature in spindle system have beenobtained. Then the temperature load have been added to the physical structure , thethermal deformation was obtained.Thermal-structure coupling analysis post-processing and thermal deformationresult of the headstock as follows:Five: Conclusion:1,This paper analysis the stable state and the transient state heat transfer processof the headstock and the spindle system , then carries on the reasonable simplificationto it.2, , studies about surface thermal transfer rule of the headstock and the spindlesystem by using the boundary-layer theory .And then infers the thermal transfercoefficient computational method of this model.3, establishment and revision simplification of the machine tools headstock andspindle system model. Including thermal transfer model, physical model as well asfinite element model.4, thermal deformation computation of headstock and the spindle system.5, Base on the result of the thermal deformation, putting forward theoptimization goal of the thermal structure to the spindle model.6, the introduction and the research of thermal deformation compensates controltechnology.