GB/T 145-2001 English PDF (GBT145-2001)

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GB/T 145-2001: Center holes
GB/T 145-2001
ranslated English of Chinese Standard: GB/T145-2001
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.010
J 05
Replacing GB/T 145-1985
Center holes
中心孔
ISSUED ON: JULY 20, 2001
IMPLEMENTED ON: MARCH 1, 2002
Issued by: General Administration of Quality Supervision, Inspection
and Quarantine of the People’s Republic of China
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Types and sizes ... 4 
Foreword
In this Standard, Type A center holes are equivalent to the type and size of
the Type A center holes in the Appendix of the international standard ISO
866:1975 Centre drills for centre holes without protecting chamfers - Type A;
Type B center holes are equivalent to the type and size of the Type B center
holes in the Appendix of the international standard ISO 2540:1973 Centre
drills for centre holes with protecting chamfer - Type B; and Type R center
holes are equivalent to the type and size of the Type R center holes in the
Appendix of the international standard ISO 2541:1972 Centre drills for centre
holes with radius form - Type R. In this Standard, Type C center holes are
equivalent to the German standard DIN 332/2-1970 Center holes 60° with
thread for shaft ends for rotating electrical machines. This Standard is a
revision of GB/T 145-1985.
This Standard adds “Foreword”, “Chapter 1 Scope”, and “D2 size of Type C
center holes” on the basis of the original standard. The article numbers and
contents in each chapter have changed slightly.
This Standard replaces GB/T 145-1985 from the date of implementation.
This Standard was proposed by the China Machinery Industry Federation.
This Standard shall be under the jurisdiction of the National Technical
Committee for Standardization of Tools.
Main drafting organization of this Standard: Chengdu Tool Research Institute.
Main drafter of this Standard: Xia Qian.
This Standard was first published in June 1959 and first revised in June 1985.
Center holes
1 Scope
This Standard specifies the types and sizes of the Type A, Type B, Type C,
and Type R center holes.
This Standard applies to the Type A, Type B, Type C, and Type R center
holes.
2 Types and sizes
2.1 The type of the Type A center hole is shown in Figure 1, and the sizes
are given in Table 1.
Figure 1