QC/T 870-2022Double end studs bm=1.25d (English PDF)

Foreword

This document was in accordance with the requirements of GB/T 1.1-2020 "Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents".

This document replaces QC/T 870-2011 "Double end studs bm = 1.25d". Compared with QC/T 870-2011, except for editorial modifications, the main changes are as follows:

- CHANGE the limit deviation of "l" in the dimension from "jsl7" to "js15" (see Table 2);

- CHANGE the limit deviation of ds from "h14" to "h13" (see Table 2);

- CHANGE the limit deviation of bm from "jsl7" to "js16" (see Table 2);

- CHANGE the product grade of tolerance, in specification, from "B" to "A" (see Table 3);

- ADD the "zinc-nickel alloy" to the surface treatment type; CANCEL the oxidation (see Table 3)

- ADD the zinc-aluminum coating; ADOPT the standard "QC/T 721" (see Table 3).

1 Scope

This document specifies the type, size, technical conditions of double end studs bm = 1.25d.

This document is applicable to double end studs for automobiles, whose thread at the screw-in base end is ordinary coarse thread, transition fit thread, ordinary fine thread (thread specification is greater than M16), AND the thread at the screw-in nut end is ordinary coarse thread and ordinary fine thread.

2 Normative references

The contents of the following documents constitute the essential provisions of this document through normative references in the text. Among them, for dated references, only the version corresponding to the date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.

GB/T 2 Fasteners - Ends of parts with external thread

GB/T 90.1-2002 Fasteners - Acceptance inspection

GB/T 90.2-2002 Fasteners - Marking and packaging

GB/T 196 General purpose metric screw threads - Basic dimensions

GB/T 197 General purpose metric screw threads - Tolerances

GB/T 1167 The threads for transition fit

GB/T 3098.1-2010 Mechanical properties of fasteners - Bolts, screws and studs

GB/T 3103.1-2002 Essential oils and aromatic extracts - Determination of residual benzene content

GB/T 5779.1-2000 Fasteners - Surface discontinuities - Bolts, screws and studs for general requirements

GB/T 30512 Requirements for prohibited substances on automobiles

QC/T 326 Coding rules for automotive standardized parts […]