Structure Design And Optimization Of The High Speed And Large Cutting Depth Granite Engraving And Milling Motorized Spindle

The industrial transformation and upgrading of stone industry has put forward new requirements for the research and development of key technologies of high-grade stone processing machine tools.Stone processing machine tool is the cornerstone of the core competitiveness of the stone industry.As an important part of the stone processing machine tool,the motorized spindle’s performance directly determines the future of the stone industry.The performance of the original motorized spindle on the stone engraving machine is slightly inadequate.The motorized spindle has some problems such as overheat,serious corrosion,insufficient rigidity,low processing efficiency and short service life of spindle.Therefore,it is necessary to develop a special granite engraving and milling motorized spindle,which has the characteristics of low temperature rise,corrosion resistance,high stiffness,high efficiency machining and long life.(1)The design of a low temperature rise,corrosion resistance high speed and large cutting depth granite engraving and milling motorized spindle.The peak milling force of high speed large cutting deep processing granite was calculated.The main structural parameters of the spindle body were determined.The first critical rotational speed of the spindle body is70086.0487 rmp.The torsional stiffness of spindle body is 2.18e-6°/m.The maximum deflection of the front part of the spindle is 4.23μm,and the biggest angle is 0.00007 rad.It meets the requirements of granite processing.(2)The distribution of dendritic microchannel network on the thermal exchanger of motorized spindle was optimized.An eight-stage tree-shaped thermal exchanger was proposed.A three-dimensional fluid thermodynamic model was established and verified by experiments.The performance of tree-shaped thermal exchanger was investigated.The results showed that compared with the traditional spiral thermal exchanger,the tree-shaped thermal exchanger has many turbulent vortexes in the cooling water during heat transfer and the thermal transfer is sufficient.The temperature gradient is small and the temperature field is evenly distributed,less pumping power required,coefficient of performance is 6-8 times that of conventional spiral thermal exchangers.(3)The corrosion mechanism of the front part of the spindle was analyzed.The tree-shaped microchannel network was used for the first time in the main shaft gas seal.The tree-shaped gas seal channel and a three-dimensional aerodynamic model was established.The transient air flow field of the tree-shaped gas seal channel and the traditional gas seal channel were investigated.The results showed that the tree-shaped gas seal channel applied on the front large cover of the spindle can directly and uniformly act the sealed gas on the front part of spindle.The seal gas form a turbulent vortex at the handle of the engraving milling cutter,and the gas accelerated flushing of engraving milling cutter,which has a higher gas sealing efficiency.(4)A complete model of granite engraving and milling motorized spindle and the spindle prototype was established.The designed granite engraving and milling motorized spindle under the action of peak milling force,the static bending rigidity of spindle body is76.395N/μm,the first order natural frequency is 4281.3Hz and the first order critical speed is256878 rmp.In the operating frequency range,the dynamic deformation of the front part,middle part and back part of the spindle under the periodic excitation force is 0.14μm,0.57μm and 0.03μm.The minimum dynamic stiffness of the spindle under the working condition is566.93N/μm.It meets the requirements of granite processing.The temperature rise,vibration and machining tests were carried out on the spindle prototype and the original motorized spindle on the stone engraving machine.The temperature test results show that the temperature rise of the high speed and large cutting depth granite engraving and milling motorized spindle is obviously lower than the original motorized spindle on the stone engraving machine.The vibration test results show that the stiffness of the high speed and large cutting depth granite engraving and milling motorized spindle meet the design requirements,and the vibration of the spindle is more stable and has higher reliability.Compared the corrosion degree of the front part of the spindle after a period of operation with the exact same processing parameters,the results show that the front part of the high speed and large cutting depth granite engraving and milling motorized spindle is corroded slowly and has a good effect of delaying corrosion.Through the research of this paper,it provides necessary theoretical basis and technical support for the design and development of the high speed and large cutting depth granite engraving and milling motorized spindle.It makes up the blank of the design and development of the special engraving and milling motorized spindle for granite processing in our country.It enriches the choice of equipment for stone processing enterprises and improves the competitiveness of small and medium-sized stone processing enterprises.Efforts to promote the further development of Chinese stone industry.