TAILIEUCHUNG - Rough Surfaces thomas3

Numerical assessment | Numerical assessment employed using a light-section microscope. However if one compares the profiles shown in Fig. and the same numerical value would be obtained for each although it is obvious that the two surfaces are completely different. Therefore the simple system described above is not suitable for the types of surface produced in practical situations and it becomes necessary to devise some system which will give an average height of the profile along with some indication of the roughness of the surface. One such system in practical use is the 7 z or 10-point height method of assessing average peak-to-valley height as laid down in BS 1134 1972. This is defined as the separation of the average of the five highest peaks and the average of the five lowest valleys within a single sampling length. More involved peak-to-valley definitions have been devised notably the Allison system Hydell 1967 68 developed by General Motors and the Swedish H-system. Each system positions the peak and valley reference lines by truncating the higher peaks and lower valleys. The Allison or general surface texture GST system Fig. truncates the 10 per cent highest peaks and the lowest valleys similarly the Swedish technique involves a 5 per cent truncation to position the reference lines. In the Allison system the reference lines are termed the upper and lower GST lines and enclose the general surface texture which is considered as the workable surface between initial wear-in and a severe wear condition. The difference between the two reference lines is used as the roughness parameter GST . Outside the GST reference lines the system is reported to offer a control on the highest peaks and lowest valleys by specifying a permissible peak height and a permissible valley depth. Other peak-to-valley roughness parameters more or less widely used are listed and defined in Tables and and sect. . Fig. The Allison system of profile characterization. Upper GST .

TỪ KHÓA LIÊN QUAN
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.