刀具刃口上的定值倒棱能够提高刀具刃口强度、延长刀具寿命，但也会使切屑积聚，增大了切削阻力和切削区温度。为改善硬态切削过程中的排屑散热、降低切削阻力，提出渐变倒棱PCBN刀具结构；建立刀具刃线的数学模型，并对所建立的模型进行了数值模拟；针对渐变倒棱PCBN刀具的特征，结合端面磨削方式和化归思想，提出了逼近式磨削轨迹规划方案，通过轨迹仿真和磨削试验优选了磨削次数，实现了渐变倒棱刀具的精确磨制；提出了渐变倒棱刀具刃口缺陷、倒棱宽度和角度等参数的精度检测方法，完成了所开发刀具磨削精度的定量评价。磨削精度检测结果表明，刃口半径、倒棱宽度和角度的磨削值接近于设计值，符合精密磨削要求和硬切削加工要求。最后通过对比试验完成了对所设计刀具切削性能的验证。
The cutting edge usually has uniform chamfer in order to improve the strength of the cutting edge and extend the service life of cutting tools, but a structure with uniform chamfer can make the chip accumulated and increase the cutting resistance and the temperature of cutting zone. To improve chip removal and cooling as well as reduce cutting resistance, a structure with variable chamfer for PCBN tool is proposed. The mathematical model of the cutting edge is established, and a numerical simulation is performed base on the mathematical model. According to the characteristics of the PCBN tool with variable chamfer edge, combined with the grinding method of the end face and the idea of regression, an approximation type grinding trajectory planning is proposed. The number of grinding are optimized through a trajectory simulation, and a precision grinding of the tool with variable chamfer edge is achieved. The detection method for the edge chipping, width and angle of the chamfering of the cutting edge of the PCBN tool with variable chamfer edge is proposed, and the quantitative evaluation of the grinding accuracy is done. The results of grinding accuracy detection show that the actual grinding values of edge radius and width and angle of chamfer are consistent with the design values, which accords with the requirements of precision grinding and hard cutting. Finally, the cutting performance of the design tool is verified by the contrast test.
[1] DOGRA M, SHARMA V S, SACHDEVA A, et al. Tool wear, chip formation and workpiece surface issues in CBN hard turning:A review[J]. International Journal of Precision Engineering and Manufacturing, 2010, 11(2):341-358.
[2] DOSBAEVA G K, HAKIM M A E, SHALABY M A, et al. Cutting temperature effect on PCBN and CVD coated carbide tools in hard turning of D2 tool steel[J]. International Journal of Refractory Metals and Hard Materials, 2015, 50:1-8.
[3] KHAMEL S, OUELAA N, BOUACHA K. Analysis and prediction of tool wear, surface roughness and cutting forces in hard turning with CBN tool[J]. Journal of Mechanical Science and Technology, 2012, 26(11):3605-3616.
[4] BHEMUNI V, CHALAMALASETTI S R, KONCHADA P K, et al. Analysis of hard turning process:thermal aspects[J]. Advances in Manufacturing, 2015, 3(4):1-8.
[5] KURT A, SEKER U. The effect of chamfer angle of polycrystalline cubic boron nitride cutting tool on the cutting forces and the tool stresses in finishing hard turning of AISI 52100 steel[J]. Materials and Design, 2005, 26(4):351-356.
[6] FANG N, WU Q. The effects of chamfered and honed tool edge geometry in machining of three aluminum alloys[J]. International Journal of Machine Tools and Manufacture, 2005, 45(10):1178-1187.
[7] FULEMOVA J, JANDA Z. Influence of the cutting edge radius and the cutting edge preparation on tool life and cutting forces at inserts with wiper geometry[J]. Procedia Engineering, 2014, 69(1):565-573.
[8] ÖZEL T. Computational modelling of 3D turning:Influence of edge micro-geometry on forces, stresses, friction and tool wear in PCBN tooling[J]. Journal of Materials Processing Technology, 2009, 209(11):5167-5177.
[9] KARPAT Y, ÖZEL T. Mechanics of high speed cutting with curvilinear edge tools[J]. International Journal of Machine Tools and Manufacture, 2008, 48(2):195-208.
[10] YUSSEFIAN N Z, KOSHY P. Application of foil electrodes for electro-erosion edge honing of complex-shaped carbide inserts[J]. Journal of Materials Processing Technology, 2013, 213(3):434-443.
[11] DENKENA B, KÖHLER J, VENTURA C E H. Grinding of PCBN cutting inserts[J]. International Journal of Refractory Metals and Hard Materials,2014,42(1):91-96.
[12] VENTURA C E H, KÖHLER J, DENKENA B. Strategies for grinding of chamfers in cutting inserts[J]. Precision Engineering, 2014, 38(4):749-758.
[13] AURICH J C, EFFGEN C, KIRSCH B. Cutting edge preparation with elastic bonded superabrasive grinding wheels[J]. CIRP Annals-Manufacturing Technology, 2016, 65(1):329-332.
[14] DENKENA B, KÖHLER J, VENTURA C E H. Customized cutting edge preparation by means of grinding[J]. Precision Engineering, 2013, 37(3):590-598.
[15] DENKENA B, MEYER R. An approach to reduce the influence of tool wear on workpiece properties during hard turning[J]. International Journal of Microstructure and Materials Properties, 2009, 4(4):605-614.
[16] DENKENA B, BIERMANN D. Cutting edge geometries[J]. CIRP Annals-Manufacturing Technology, 2014, 63(2):631-653.
[17] VENTURA C E H, KÖHLER J, DENKENA B. Cutting edge preparation of PCBN inserts by means of grinding and its application in hard turning[J]. Journal of Manufacturing Science and Technology, 2013, 6(4):246-253.
[18] AURICH J C, ZIMMERMANN M, LEITZ L. The preparation of cutting edges using a making laser[J]. Production Engineering, 2011, 5(1):7-24.
