Tab_2_Symbols-几何公差符号与标准

Symbols & Rules – Section 2 Page 2-1 Standards Equivalent Comparison Technical Drawings ASME Y14 Series ISO Standards Y14.2 – Lines & Lettering 128-20, -21, -22, -24 3098-0, -1, -2, -3, -4, -5 Y14.3 – Sections & Views 128-30, -34, -40, -44, -50 Y14.5 – Dimensioning & Tolerancing Y14.5.1 – Mathematical Definition of Dimensioning & Tolerancing Y14.5.2 – Certification of Geometric Dimensioning & Tolerancing Professionals Y14.41 – Digital Product Definition Data Practices 129, 406, 1101, 1660, 2692, 5455, 5458, 5459, 5460, 6411, 6413, 7083, 8015, 10578, 10579, 14660-1, 14660-2 (17) Y14.6 – Screw Thread Representation 5845-1, 5845-2 6410-1, 6410-2, 6410-3 Y14.8 – Casting & Forgings 10135 Y14.36 – Surface Texture Symbols 1302 Symbols & Rules – Section 2 Page 2-2 Keys to Geometric Dimensioning & Tolerancing (GD&T) “Function” and “Relationship” ************************************************************************************ Relationship Between Features ASME Y14.5-1994, para 2.7.3 • The limits of size do not control the orientation or location relationship between individual features. • Features shown perpendicular, coaxial, or symmetrical to each other must be controlled for location or orientation to avoid incomplete drawing requirements. Symbols & Rules – Section 2 Page 2-3 Geometric Symbols Type of Tolerance Characteristic Symbol For: ASME Y14.5M ISO Straightness Flatness Circularity Individual Features FORM Cylindricity Profile Of A Line Related or Individual Features PROFILE Profile Of A Surface Angularity Perpendicularity ORIENTATION Parallelism Position Concentricity (and Coaxiality in ISO) LOCATION Symmetry Circular Runout Related Feature RUNOUT Total Runout Symbols & Rules – Section 2 Page 2-4 Symbol For: ASME Y14.5M ISO At Maximum Material Condition M M At Least Material Condition L L Regardless of Feature Size NONE NONE Projected Tolerance Zone P P Tangent Plane T T Free State F F Diameter Spherical Diameter S S Square Number Of Places X X Arc Length 10 10 Radius R R Spherical Radius SR SR Controlled Radius CR NONE Conical Taper Slope Counterbore/Spotface Countersink Depth/Deep All Around Between NONE Statistical Tolerance ST NONE Symbols & Rules – Section 2 Page 2-5 Radius, Controlled Radius Min Radius 12.3 Min Radius 12.3 Max Radius 12.7 Max Radius 12.7 All points of the produced feature must fall within a zone defined by Max and Min radius Radius, R Controlled Radius, CR On drawing Meaning On drawing Meaning 12.7 12.3R 12.7 12.3 CR Produced contour must be a smooth feature with no reversals in the transision. All radii points must be within 12.3 - 12.7. Symbols & Rules – Section 2 Page 2-6 Statistical Tolerance Symbol Application 0.2 A B 0.5 A BST ST Ø 20.2 20.8 Ø 16.1 15.9 Ø 16.03 15.98 B A 40 NOTE: FEATURES IDENTIFIED WITH SHALL BE PRODUCED WITH STATISTICAL PROCESS CONTROLS, OR TO THE MORE RESTRICTIVE ARITHMETIC LIMITS. ST Symbols & Rules – Section 2 Page 2-7 Free State Application 3 F 2 SURF 2 SURF 4X 5.4 - 5.6 65 32 36.8 5.6 AØ 0.2 M B UNLESS OTHERWISE SPECIFIED, ALL UNTOLERANCED DIMENSIONS ARE BASIC. PART IS TO BE RESTRAINED ON DATUM A WITH 4 5M SCREWS A 5225 Symbols & Rules – Section 2 Page 2-8 Basic Dimension (theoretically exact dimension in ISO) 65 Reference Dimension (auxiliary dimension in ISO) (68) A Datum Feature A Dimension Origin Feature Control Frame CBAØ 0.5 M Datum Target Area Ø8 A1 A1 Ø20 Datum Target Point A1 Datum Target Line A1 Symbols & Rules – Section 2 Page 2-9 Dimension Origin Symbol 28 26 26 28 MEANS THIS INDICATES ORIGIN PLANE 262 8 NOT THIS THIS Symbol Symbols & Rules – Section 2 Page 2-10 Five possible parts of a Feature Control Frame 0.6 CBAØ 0.5 CBAØ 0.5 M M Symbols & Rules – Section 2 Page 2-11 Rule 2: Applicability of Material Condition Æ ASME Y14.5-1994, para 2.8 Æ For All Applicable Geometric Tolerances: RFS applies (Regardless of Feature Size), with respect to the individual tolerance, datum reference, or both, where no modifying symbol is specified. Æ ASME Y14.5-1994, para 2.8 (continued) Æ MMC or LMC must be specified on the drawing where it is required. (or desired, determined by the design) Æ In 1982 standard, Rule #2 required the use of material modifier with Position Feature Control Frame CBAØ 0.5 AØ 0.4 CBAØ 0.5 M M LSM Symbols & Rules – Section 2 Page 2-12 Pitch Rule ASME Y14.5-1994, para 2.9 a) Each tolerance of orientation or position and datum reference specified for a screw thread applies to the axis of the thread derived from the pitch cylinder. If desired to apply to either Major Diameter or Minor Diameter, it must be spelled out under the FCF. Internal Thread (tapping) External Thread (screw) Symbols & Rules – Section 2 Page 2-13 Pitch Rule Continued ASME Y14.5-1994, para 2.10 b) Each tolerance of orientation or position and datum reference specified for features other than screw threads, such as gears and splines, must designate the specific feature to which each applies. A CAØ 0.5 MB BAØ 0.5 M PD MAJOR Ø PD MAJOR Ø Symbols & Rules – Section 2 Page 2-14 H U B TO LE R A N C E ± 0 .5 A N G LE ± 2 ° Exercise – Section 2 Page 2-15 1. Name the five types of geometric characteristic symbols. 1) ________________ 2) __________________ 3) __________________ 4) ________________ 5) __________________ 2. Any letter of the alphabet can be used to identify a datum except for ____, ____, or ____. 3. Name each of the following geometric characteristic symbols. __________________________________ ___________________________________ ____________________________________ ____________________________________ __________________________________ ____________________________________ ___________________________________ ___________________________________ __________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ __________________________________ Exercise – Section 2 Page 2-16 4. Label the parts of the following feature control frame. 5. What is the difference between a conventional dimension and a basic dimension? _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Sketch how a basic dimension is shown on a drawing: