tailieunhanh - Engineering Drawing for Manufacture phần 9

Hiện nay không có tiêu chuẩn tham số 3D. Còn quá sớm trong chu kỳ phát triển. Nghiên cứu vẫn còn cần thiết để khám phá những khả năng và cung cấp các khuyến nghị. Một chương trình nghiên cứu được thực hiện bởi Đại học Birmingham đã dẫn đến một đề nghị cho một số thông số 3D và rằng họ cần phải có chỉ định tham số 'S' "bề mặt" (Stout et al, 1993 và 2000). | 130 Engineering drawing for manufacture 3D surface characterization At present there is no 3D parameter standard. It is too early in the development cycle. Research is still needed to explore the possibilities and provide recommendations. A research programme undertaken by Birmingham University has led to a proposal for some 3D parameters and that they should have the parameter designation S for surface Stout et al 1993 and 2000 . The proposal was for the recognition of a primary set of 14 3D parameters. They are mostly 3D versions of 2D parameters . Rq to Sq. However proposals were made concerning areal bearing area parameters which seem particularly useful. Research continues at various establishments and two EU funded research programmes are of note that were reported in 2001. One was concerned with 3D parameter specification in general called Surfstand and the other was concerned with the 3D assessment of automotive body panels called Autosurf . These two reports recommend that a series of 3D parameters should be defined in two Technical Reports that will be published in 2002 as consultation documents. Since these 3D parameters are at present more appropriate to the laboratory than the factory they will not be discussed any further here. Surface finish specification in the real world When it comes to drawing a part to be manufactured for real it is not necessary to add an SF specification to each and every feature. The vast majority of features do not need them since the common manufacturing processes achieve the SF required and more often than not the SF is unimportant. It is only in a few instances where a surface is functionally important that it is necessary to define a SF. Indeed specifying a SF is the exception rather than the rule and I have seen many drawings that do not have any SF specifications on them at all Note that the vice assembly drawing in Figure has no SF specification. This should not be surprising since it is an assembly .