GB/T 4267-2004
Rotating tools with parallel shanks-Diameters of shanks and sizes of driving squares

Standard No.

GB/T 4267-2004

Language

Chinese

Release Date

2004

Published By

General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China

Lastest

GB/T 4267-2004

Scope

This standard specifies the diameter of the shank and the size of the transmission square head for straight shank rotary tools (such as reamers, taps, etc.). This standard includes two dimension series: the first series and the second series. Each series lists dimensions in millimeters and their imperial equivalents. For each series, the drive square size for a given diameter is also listed. The entire diameter range, divided into several diameter segments. Corresponding standard square head sizes are listed for each diameter segment not only for the first series but also for the second series because subdivision is absolutely necessary for some applications in the small diameter area. In each metric size table, the dimension α across sides of the square head and the priority diameter d are arranged according to the priority number R20 series; the upper and lower limits of each diameter segment are the intermediate values taken according to the priority number R40 series. In each inch size table, the α and d values are converted from the corresponding metric values, the square head size is taken to the third decimal place, and the diameter size is taken to the fourth decimal place. In the first series, in addition to listing the upper and lower limits of each diameter segment, each table also lists the preferred diameter for each diameter segment (see the following table), and the ratio of the size of the square head to the preferred diameter is equivalent. At the theoretical optimum value α/d=0.8. In any one diameter segment, the ratio α/d is between 0.75 and 0.85 for the first series and between 0.80 and 0.85 for the second series, which is calculated on the basis of the nominal values of α and d, considering their tolerances , not less than 0.72 in the worst case.

GB/T 4267-2004 history

• 2004 GB/T 4267-2004 Rotating tools with parallel shanks-Diameters of shanks and sizes of driving squares
• 1984 GB/T 4267-1984 Rotating tools with parallel shanks--Diameters of shanks and sizes of driving squares