【摘要】：由于碳纖維增強復合材料(CFRP)具有比強度高、比模量大等優(yōu)異性能,在航空航天、國防行業(yè)具有廣泛的應用前景。復合構件成型后,往往需要根據(jù)裝配要求進行二次加工,然而,在碳纖維增強復合材料加工中易出現(xiàn)毛刺、分層等加工缺陷,以及刀具磨損等問題。論文以彈托主要表面的加工應用為研究對象,圍繞加工機理、刀具磨損、刀具材料和結構、加工工藝參數(shù)等影響因素對CFRP材料的加工進行了試驗研究和理論分析。以碳纖維增強復合材料的銑削加工為研究對象,通過試驗觀察,對CFRP材料的切削加工機理進行了研究。結果表明:在工件平放銑削方式下,切屑的典型類型主要有塊狀切屑和卷曲狀切屑;在工件立放銑削方式下,切屑的典型類型主要有長條狀切屑;在實際銑削加工中采用逆銑的銑削方式能減小加工缺陷;在切削過程中,纖維呈脆性斷裂,纖維所受應力不同,將形成不同的纖維斷口形貌,主要的斷口形貌有光滑平面斷口、傾斜斷口、多階平面斷口、不規(guī)則斷口、波紋狀斷口,以及長斜面和不規(guī)則狀斷口組合而成的斷口等。采用硬質合金(YG6X,未涂層)及其DLC涂層立銑刀,以及釬焊PCD刀片立銑刀分別進行CFRP材料的銑削試驗,分析了它們的磨損特征和磨損機理。結果表明,這三種刀具均出現(xiàn)磨粒磨損和樹脂粘附等磨損形態(tài),而涂層剝落和成塊剝落破損分別為DLC涂層刀具和PCD刀具的特有磨損形態(tài)。此外,CFRP材料的鉆銑試驗結果表明,DLC涂層刀具和PCD刀具均為CFRP材料切削加工的理想刀具。使用不同結構的鉆頭進行鉆削加工試驗,結果表明,當鉆頭直徑超過10mm時,制孔缺陷和鉆削軸向力均呈大幅增大;采用多刃尖鉆和匕首鉆鉆削CFRP材料時,孔出口制孔缺陷有明顯減小,其中匕首鉆的最小。為進一步了解匕首鉆的鉆削過程,還建立了匕首鉆的鉆削模型及其臨界軸向力模型,分析了孔出口缺陷的形成過程,揭示了孔出口缺陷較小的原因,并且獲得了分層產生和擴張的臨界軸向力值。通過CFRP材料的銑削試驗,分析了刀具材料、刀具結構和銑削方式等對切削力和加工缺陷的影響,優(yōu)化了銑削加工的工藝參數(shù)。以減小銑削力和銑削分層因子為目的,切削速度Vc、進給量f和銑削深度αp分別在63～109m/min、0.02～0.18mm/r和1～3mm下,采用PCD立銑刀對CFRP材料進行正交試驗,獲得了切削速度Vc、進給量f和銑削深度αp的最優(yōu)組合,即分別為63m/min、0.02mm/r和1mm。為考察齒槽的切制過程和加工缺陷,采用T型銑刀對CFRP材料進行齒槽加工試驗,從理論分析和試驗研究兩個方面,分析了齒槽加工缺陷的形成過程及其變化規(guī)律,獲得了齒槽加工每齒進給量的合適范圍。在此基礎上,通過進一步的齒槽加工試驗,分析了刀具材料、刀具結構、銑削方式和工藝參數(shù)等對齒槽加工缺陷和切削力的影響。針對CFRP復合構件的加工進行試驗,確定了車削、鏜削和孔內齒槽加工的工藝參數(shù)(切削速度Vc、進給量f和背吃刀量αp),獲得了孔內齒槽加工刀片和走刀路徑的合理方案。至此,在鉆、銑、車、鏜等加工研究的基礎上,通過擬定的加工工藝路線,完成了復合構件120°夾角側面、端面、外圓、深孔和孔內齒槽的加工。在CFRP復合構件的加工過程中,刀具使用性能和加工質量均能得到有效保障。
[Abstract]:Carbon fiber reinforced polymer (CFRP) has a wide range of applications in aerospace and national defense industry because of its high specific strength and modulus. In this paper, the machining mechanism, tool wear, tool material and structure, processing parameters and other influencing factors of CFRP material are studied experimentally and theoretically. The milling process of carbon fiber reinforced composites is studied. The cutting mechanism of CFRP material is studied by experiment and observation. The results show that the typical types of chips are block chips and curly chips in workpiece horizontal milling, strip chips in workpiece vertical milling, and reverse milling in actual milling. In the cutting process, the fiber is brittle fracture, and the stress of the fiber is different. The main fracture morphologies are smooth plane fracture, inclined fracture, multi-level plane fracture, irregular fracture, corrugated fracture, long inclined fracture and irregular fracture. The milling tests of CFRP materials with cemented carbide (YG6X, uncoated) and its DLC coated end milling cutters and brazed PCD insert end milling cutters were carried out respectively, and their wear characteristics and wear mechanism were analyzed. In addition, the results of drilling and milling experiments on CFRP materials show that both DLC coated and PCD tools are ideal tools for cutting CFRP materials. When drilling CFRP material with multi-edge point drill and dagger drill, the hole-making defect at the exit of the hole is obviously reduced, and the dagger drill is the smallest. The critical axial forces for delamination generation and expansion are obtained. The effects of tool material, tool structure and milling method on cutting force and machining defects are analyzed by milling experiments of CFRP material. The milling process parameters are optimized. The cutting speed Vc, feed F and milling factor are used to reduce the milling force and delamination factor. The optimum combination of cutting speed Vc, feed F and milling depth alpha P was obtained by orthogonal test of CFRP material with PCD end milling cutter at the depths of 63-109 m/min, 0.02-0.18 mm/r and 1-3 mm, respectively. In order to investigate the cutting process and machining defects of groove, the T-type milling cutter was used to carry out tooth cutting of CFRP material. In the groove machining experiment, the forming process and changing rule of groove machining defect are analyzed theoretically and experimentally, and the suitable range of feed per tooth is obtained. Based on the experiments of machining CFRP composite components, the technological parameters of turning, boring and groove machining in the hole (cutting speed Vc, feed F and back feed alpha p) are determined, and the reasonable scheme of groove machining insert and tool path in the hole is obtained. Through the proposed processing route, the processing of 120 degree angle side, end face, outer circle, deep hole and inner groove of CFRP composite component is completed.
【學位授予單位】：南京理工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB332

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