tailieunhanh - Machinability and Surface Integrity Part 11

Tham khảo tài liệu 'machinability and surface integrity part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Machinability and Surface Integrity 369 Figure 189. The influence of the cutting edge s condition on the resultant machined surface integrity 370 Chapter 7 In Fig. 189c a white-layer . for this ferrous drilled part being a localised untempered martensitic phase of 63 HRc91 exists beneath the recast and redeposited layer in this case produced by a dull drill s cutting lips and margins. Due to the fact that the recast layer . heat-affected zone - HAZ has a similar metallurgy to that of the white-layer with the delineation of these white-layers regions and their accompanying HAZ s are not clearly defined. This latter HAZ is a complex metallurgical condition comprising of some untempered martensite UTM over-tempered martensite OTM while beneath these layers the bulk substrate material remains unaffected. The thickness of these white-layer zones is strongly influenced by both the actual plastic deformation created here and to a lesser degree by the thermal influence of the passage of the tool s edge over the machined surface as heat penetrates into the locality of the component s surface. Probably the worst abusive machining conditions that can exist are when drilling holes in workhardening materials having long length-to-diameter ratios . L D ratios of 12 1 with inadequate coolant supply creating high levels of friction this condition being exacerbated by an inefficiency produced by a dulled drill s cutting lips. Virtually all tooling even the most sharp - the notable exception here being monolithic faceted natural diamond cutting edges have a finite tip radius of 8 gm . see Fig. 184 - high-lighting the tool tip rounding effect this results in increased forces and tool wear which can transform the surface metallurgy by thermo-mechanical generation. The case has already been made concerning the fact that machining processes impart residual stresses into the surface layers as indicated in the schematically-represented milling conditions shown in Fig. 190 and

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.