BS ISO 4468:2020 pdf free.Gear hobs一- Accuracy requirements.
BS ISO 4468 In addition to the elemental tests for hobs, this document gives permitted tolerances for composite tests that are taken along the cutting edges on the line of action. The two groups of tests are not equivalent and one can choose between one or the other. If there was no previous agreement, the hob is regarded as belonging to the precision class specified if it satisfies one or the other of the two methods of inspection. NOTE The tolerances in this document were determined for gear hobs whose dimensions conform to ISO 2490, but with certain precautions they can be applied to hobs not specified in this document.The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 286-2, Geometrical product specifications (GPS)一ISO code system for tolerances on linear sizes一 Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts
ISO 1122-1, Vocabulary of gear terms一Part 1: Definitions related to geometry ISO 2768-1, General tolerances一Part 1: Tolerances for linear and angular dimensions without individual
tolerance indications.axial pitch deviation from thread to thread maximum axial pitch deviation between any two consecutive teeth contained within two gashes Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even number of threads, it is approximately 120°.axial pitch deviation in any three axial pitches over all threads maximum axial pitch deviation over any three adjacent teeth contained within two gashes Note 1 to entry: For an odd number of threads, the angle between the gashes is approximately 90°. For an even number of threads, it is approximately 120°.No particular method of measurement or documentation is considered mandatory. When applications
require measurements beyond those recommended in this document, it is recommended to negotiate special measurement methods prior to manufacturing the hob.BS ISO 4468 pdf download.