ISO 10303-47:1997 pdf download – lndustrial automation systems and integration- Product datarepresentation and exchange — Part 47: lntegrated generic resource: Shape variation tolerances.
4.1 Introduction
The subject of the shapr ispect_dcfinition schema is to provide dctinitioris at the spatial daractertstics of a shape that are requed tiw diiirnsiunmg and tntetancing This schema provides represaatnms 1& a derived – shape aspect and a datum. A derived shape_aspect is a shape…aspect that is developed tram the defined shape 0 the product. but that is not required tar dctinin the product shape. A datum is a .shape_ aspect that provide the arigm fruai where dimenuans and takranccs are reterencest A derived_shape_aspect and a datum ate ts oldie shape that are required for dimensiLaung and loletaiscuig the sue. the Location, the orientation. and the forimi of a product shape.
4.2 Fundamental concepts and assumptions
The pioduct shape is the concept at drape as a properly that charactcm’es a product. Geometric models and engineering drawings are tirmal methods wie4i to represent the product shape. Dimensions and tolerances arc elenienis of die pruduct shape defmititm wbch are independent tram how the shape is represented. Dimensions may be explicitly identi lied as part of the shape cl ractenstics. implicitly included in a geomctrK model that represents the shape. ar explicitly piesCntcd in a Iwu-dirrcnsianai drawing.
A shape aspect is an element of a product shape. Diiiensitns may be specified tie both the entire product shape and aspecisof the shape. This schema augments the shape aspects and the relationships among them as the dclinitkmai mechanism for specitying dimensions and tolerances. A shape aspect, relationships between shape_aspect elements. and thcu specified dimensions and tolerances are always deflned rn the context (lithe product shape properly. These dimensions arid tolerances can be represented as elements of geometric riu1els or engineering drawings.
mr the parpisse iii identifying dimensions and tolerances, this schema specilics the concept at a derived shape_ aspect. A derived shape aspect is a shape aspect that is defined based an the specific way in which it relates to another shape aspect. The derived shape aspect is used In Conjunction with their related shape aspect elenic,its to specify dimensions and tolerances. The specific geometry that can reptesent the derived shap_aspect and a shape_aspect that provide the detinhtional relationship are not in the scope of this schema. The geometry, the rcp(esenlation tnicturc. and their awciation to the dimension and tolerance dcmcnis specified tn this pan arc defined in ISo 10303-41, ISO 1030342, and ISO 10303-43. Only the generic concept of derived shapeaspect is specified here. Application protocols may specify additional derived shape_aspect elements from thOLSc provided.
NOTE. Legal vabes that arc coiqsicr scasihk fix attributes of ctititir.s in this schema may bc specified itt ipphcauirn fotocolS.
43 shape_aspect_definition_schema type definition: limit condition
A limit condition type indicates that a tolerance may have a material moditier condition applied. This moditier allows for the addition of material to, or (or the reduction of material from a IeanEe The use of limIt condition applies only to toleranced features and datum features that have size characteristics.
EXAMPLE I The diameter of a hole ci of a shaft ci die width cia ales are size chariicicnslics which may have a IlinIt_coedlflon spplini.
EXPRESS specification:
TYPE limit_condition ENUMERATION OF maxinannjnaterial_conditiori, least_material_condition, regardl.ea_of_teatura_size);
Enumerated item definitions:
maxlmtmt_nsatertal_condltlon: the state of a feature when it contains its nla,umum material with respect to its specified limit of size. Matinaim nsituial condition is defined in clause 3.3 of ISO 2692. The methods described in ISO 2692 kw applying maxImummaterlal condItion to datums and toleranced features shall he followed.
NOTE I – Fix a diape aspret which LS sold olnadedal. the .saximu._nsaterlalco.dltion the anuillcsr misusurt of this featurt of site, e.g.. the smaflcat diameter of a hole.
least_material_conditIon: the state of a feature when it contains its least material with resped to its specified limit of size. Least material condition is defined in dairie 35 of ISO 2692. The methods described in amendment I of ISO 2692 for applying least_material_condition to datums and inleranced features shall be followed.