Tham khảo tài liệu 'sổ tay tiêu chuẩn thiết kế máy p23', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CHAPTER 19 LIMITS AND FITS Joseph E. Shigley Professor Emeritus The University of Michigan Ann Arbor Michigan Charles R. Mischke . . Professor Emeritus of Mechanical Engineering Iowa State University Ames Iowa INTRODUCTION METRIC STANDARDS . STANDARD INCH UNITS I INTERFERENCE-FIT STRESSES I ABSOLUTE TOLERANCES STATISTICAL TOLERANCES REFERENCES NOMENCLATURE a Radius B Smallest bore diameter b Radius c Radius radial clearance D Diameter mean of size range largest journal diameter E Young s modulus e Bilateral tolerance expressing error L Upper or lower limit p Probability Pf Probability of failure t Bilateral tolerance of dimension w Left-tending vector representing gap x Right-tending dimensional vector magnitude y Left-tending dimensional vector magnitude 3 Radial interference v Poisson s ratio ct Normal stress CT Standard deviation STANDARD HANDBOOK OF MACHINE DESIGN INTRODUCTION Standards of limits and fits for mating parts have been approved for general use in the United States for use with . customary units and for use with SI units . The tables included in these standards are so lengthy that formulas are presented here instead of the tables to save space. As a result of rounding and other variations the formulas are only close approximations. The nomenclature and symbols used in the two standards differ from each other and so it is necessary to present the details of each standard separately. METRIC STANDARDS Definitions Terms used are illustrated in Fig. and are defined as follows 1. Basic size is the size to which limits or deviations are assigned and is the same for both members of a fit. It is measured in millimeters. 2. Deviation is the algebraic difference between a size and the corresponding basic size. 3. Upper deviation is the algebraic difference between the maximum limit and the corresponding basic size. 4. Lower deviation is .
