| In modern machining, the excessive use of cutting fluid caused seriousenvironmental pollution and waste of resources. With the improvement of the awarenessof ecological environmental protection, green machining methods, such as MinimumQuantity Lubrication(MQL) cutting, is concerned by domestic and foreign scholars.Minimum quantity lubrication technique can be understood as a small quantity oflubricating oil mixed with compressed air flow resulting in moisture that is delivered inthe tool-workpiece interface.In this paper, the cutting experimental of hardened45steel and206stainless steelwith Al2O3ceramic tool under MQL condition was designed, and the tool flank wear indifferent cutting parameters was compared. To provide a theoretical basis for the actualcutting of MQL technology. The paper includes the following sections:1.Bases on the MQL cutting research of scholars, and the recommended parametersof the MQL system used in this study. The optimum cutting parameters of MQL systemwas determined: air pressure is0.6MPa, oil consumption is10ml/h, the distancebetween nozzle and too is20mm, the angle is15-20o; The cutting conditions wasselected, such as cutting fluid, workpiece, tool and geometry, cutting parameters.2. The reasonable experimental program were developed for hardened45steel and206stainless steel cutting, and cutting experiment were conducted. By comparing thevalue of the tool flank wear under different cutting conditions, to learn MQL cutting anddry cutting tool wear state. Use the scanning electron microscopy to observe themorphology of tool flank wear, compare the effects of different lubrication conditionson the tool flank wear. Summed up the best of cutting parameters in MQL condition: Inhardened45steel cutting process, the cutting speed is90m/min, cutting depth is0.5mm,feed rate is0.102mm/r or0.198mm/r; In206stainless steel cutting process, the cuttingspeed is147m/min, cutting depth is0.5mm, feed rate is0.054mm/r or0.102mm/r.3. In the hardened45steel cutting process with speed of90m/min, due to the lowspeed, impact load generated in the nose, resulting in the tool wear was dramatic inMQL and dry cutting, and the nose broken easily; When the speed is90m/min, MQLtechnology has played a significant role in cooling and lubrication, the values of toolflank wear in MQL cutting were less than dry cutting; when the speed is110m/min, thetrend of flank wear in MQL and dry cutting are similar. This is because with increased cutting speed, there are produced a large amount heat and high temperature in contactzone. The effect of cooling and lubrication in MQL cutting is not enough.The main form of flank wear is abrasive wear due to due to high hardness ofworkpiece. Moreover, there is a deep trench in flank wear band under MQL cutting. This isbecause in MQL cutting, the oil mist cannot fully into the middle of the cutting area.(4) In the206stainless steel cutting process, due to the low hardness and highductility, the main form of flank wear is adhesive wear, this lead to a large amount ofburr generated on the surface of workpiece, the effect is very seriously for workpiecesurface quality.It is similar to hardened45steel cutting process, with the low speed and high feedrate, due to the low speed, impact load generated in the nose, resulting in the tool wearwas dramatic in MQL and dry cutting, and the nose broken easily. With the increase ofcutting speed, the shape of tool wear band is more smooth, there is no damagephenomenon on the nose.The cutting tool life under different conditions were compared. in hardened45steel cutting, the tool life in MQL cutting is2.1times to dry cutting. In206stainlesssteel cutting, the tool life in MQL cutting is4times to dry cutting. Which shows thatMQL technology can be effectively cooling and lubricating the cutting zone, thussignificantly improve tool life. Further, the oil consumption was counted during MQLcutting, the important role of cost saving in MQL cutting was further evidenced. |
PDF Full Text Request