GB/T 145-2001Center holes (English PDF)

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

2.1 The type of the Type A center hole is shown in Figure 1, and the sizes

are given in Table 1.

2.2 The type of the Type B center hole is shown in Figure 2, and the sizes

are given in Table 2.

2.4 The type of the Type R center hole is shown in Figure 4, and the sizes

are given in Table 4.

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