GB/T 18685-2002 in English

《GB/T 18685-2002搓、滚制普通螺纹前的毛坯直径》由TC108（全国螺纹标准化技术委员会）归口，主管部门为国家标准化管理委员会。
本标准规定了搓、滚制普通螺纹前的毛坯直径尺寸。本标准适用于全牙型挤压工艺加工钢或合金钢材料的普通螺纹。

Scope

This standard specifies the bar diameters for rolling general purpose metric screw threads.

This standard is applicable to the general purpose metric screw threads finished steel or alloy steel materials manufactured by full-profile extrusion process.

Note: "full-profile extrusion process" refers to the processing method in which the thread materials completely fill the bottom space of the cutting tool when the thread is extruded.

2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, all editions cited are valid. All standards are subject to revision, and all parties using this standard are encouraged to investigate the possibility of applying the latest editions of the following standards.

GB/T 192-1981 General purpose metric screw threads - Basic profile (eqv ISO 68-1:1998)
GB/T 193-1981 General purpose metric screw threads - Diameters and pitches (diameters from 1 to 600mm) (eqv ISO 261:1998)
GB/T 196-1981 General purpose metric screw threads - Basic dimensions for diameter from 1 to 600 mm) (eqv ISO 724:1993)
GB/T 197-1981 General purpose screw threads - Tolerances and fits for diameter from 1 to 355mm (eqv ISO 965-1:1998)
GB/T 971-1994 Thread rolling cylindrical dies
GB/T 972-1994 Thread rolling flat dies
GB/T 3934-1983 Gauges for general purpose screw threads (neq ISO 1502:1996)
GB/T 10920-1989 Types and dimensions of gauges for general purpose screw threads (neq ISO 3670:1979)
GB/T 14791-1993 The terms of screw threads (neq ISO 5408:1983)

3 Definitions

Foreword II
1 Scope
2 Normative references
3 Definitions
4 Calculation formula of bar diameter
5 Limit dimensions of bar diameter
6 Grade selection of cutting tool
7 Adjustment of bar diameter
Annex A (Normative) Calculation formula of bar diameter