ASME B89.4.19-2021 pdf download
ASME B89.4.19-2021 pdf download.Performance Evaluation of Laser-Based Spherical Coordinate Measurement Systems.
Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes thatappear necessary or desirable, as demonstrated bythe experience gained from the application ofthe Standard. Approved revisions will be published periodically. The Committee welcomes proposals for revisions to this Standard. Such proposals should be as specific as possible, citing the paragraph number(s), the proposed wording, and a detailed description of the reasons for the proposal, including any pertinent documentation. Proposing aCase. Cases maybe issued to provide alternative rules when justified, to permitearlyimplementation of an approved revision when the need is urgent, or to provide rules notcovered byexisting provisions. Cases are effective immediately upon ASME approval and shall be posted on the ASME Committee web page. Requests for Cases shall provide a Statement of Need and Background Information. The request should identify the Standard and the paragraph, figure, or table number(s), and be written as a Question and Reply in the same format as existing Cases. Requests for Cases should also indicate the applicable edition(s) ofthe Standard to which the proposed Case applies. Interpretations. Upon request, the B89 Standards Committee will renderan interpretation ofanyrequirementofthe Standard.InterpretationscanonlyberenderedinresponsetoawrittenrequestsenttotheSecretaryoftheB89 Standards Committee. Requests for interpretation should preferably be submitted through the online Interpretation Submittal Form. The form is accessible athttp://go.asme.org/InterpretationRequest. Upon submittal ofthe form, the Inquirer will receive an automatic e-mail confirming receipt.
Inadditiontoprovidingfortheperformanceevaluationoflasertrackers,thisStandardfacilitatesperformancecompar- isons among different systems by unifying the terminology and the treatment of environmental factors. It defines test methods appropriate forevaluatingthe performance ofa majorityoflasertrackers, butitis notintended to replace more complete tests that may be required for special applications. Systems that have passed the performance evaluation tests of this Standard are considered capable of producing traceable point-to-point length measurements for the conditions required herein. Application of point-to-point length measurements to a specific workpiece or measurement task may require additional testing and analysis in order to establish metrological traceability. This Standard provides technical guidance that may be useful in the cali- bration of laser-based spherical coordinate systems for point-to-point length measurements. The Appendices describe various factors that should be considered when using this Standard. (a) Mandatory Appendix I discusses metrological traceability, with particular focus on demonstrating traceability of reference lengths used in laser tracker performance evaluation. Requirements for demonstrating metrological trace- ability are presented per ASME B89.7.5. (b) Nonmandatory Appendix A discusses the traceability of laser tracker point-to-point length measurements performed subsequent to a system passing the performance evaluation tests described in this Standard. (c) NonmandatoryAppendixB describes tests andprocedures fordetermininggeometricerrors intheconstructionof SMRs so that the suitability of a particular SMR for laser tracker performance testing can be evaluated. (d) NonmandatoryAppendixC describes environmentalfactors thatinfluencethe refractiveindexoflightinair. These factorsaffectthewavelengthoflightandshouldbecarefullyunderstoodbeforeproceedingwiththetestsdescribedinthis Standard.
(e) Nonmandatory Appendix D describes four methods that can be used to establish a calibrated reference length for point-to-point length measurement system tests. Uncertainties in realization of such lengths are discussed. Nonmandatory Appendix D also describes the measurement capability index and the simple 4:1 acceptance decision rule used to accept or reject laser tracker performance evaluation test results. (f) Nonmandatory Appendix E describes the effects of spatial temperature gradients on laser beam propagation. Equations are derived for radial errors due to speed-of-light variations and angular (or transverse) errors due to beam refraction. A numerical example illustrates the use of the formulas. (g) Nonmandatory Appendix F describes a number of interim tests that can be used to quickly assess laser tracker measurement performance in the interval between more complete performance evaluations. This Standard prescribes performance evaluation tests that may be used by laser tracker manufacturers to generate performance specifications. These specifications are stated as the maximum permissible error (MPE) allowed for each test under specified environmental conditions. Laser trackers may be tested against the manufacturer’s specifications by using the performance evaluation tests described in section 6. A typical test involves measuring a known reference length and comparing the observed error (laser-tracker-measured length minus reference length) with the specified MPE using a 4:1 simple acceptance decision rule per ASME B89.7.3.1-2001 (R2019). The reference length orientations and laser tracker positions in the evaluation have been chosen for their sensitivity to characteristic systematic errors known to occur in these systems.
