GB/T 4459.5-1999 English PDF (GBT4459.5-1999)

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GB/T 4459.5-1999: Mechanical drawings. Representation of centre holes
GB/T 4459.5-1999
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 01.100.30
J 04
eqv ISO 6411:1982
Replacing GB/T 4459.5-1984
Mechanical drawings - Representation of centre holes
ISSUED ON: SEPTEMBER 03, 1999
IMPLEMENTED ON: MARCH 01, 2000
Issued by: State Bureau of Quality and Technical Supervision
Table of Contents
Forward ... 3
ISO Foreword ... 4
1 Scope ... 5
2 References ... 5
3 Symbols of centre holes ... 5
4 Designation of centre holes ... 6
5 Representation of centre holes ... 8
Annex A (informative) Relevant dimensions on drawings for type R, A, B and C
centre holes ... 10
Annex B (Informative) Proportions and dimensions of symbols of centres holes
... 11
Forward
This Standard is drafted in accordance with ISO 6411:1982 “Technical drawings
- Simplified representation of centre holes”. It is equivalent to the international
standard.
This Standard revises and replaces GB/T 4459.5-1984 “Mechanical drawings -
Representation of centre holes”, which makes the representation of centre
holes consistent with that in the international standard, to meet the needs of
international trade, technology and economic exchanges.
The representation of centre holes is a special representation in mechanical
drawings. This Standard supplements the following main contents as needed:
1. ADD the designation and representation of type C centre holes.
2. ADD the simplified representation, omitting the standard code in the
designation of centre holes.
3. For the convenience of selection, the parameter code in Table A1 of Annex
A adopts the provisions of GB/T 145, that is, D replaces the pilot diameter
d specified in ISO 6411, D1 replaces the tapered hole’s end face diameter
D1 (type R), D2 (type A) and D3 (type B) specified in ISO 6411.
Annex A and Annex B of this Standard are informative annex.
This Standard was proposed by State Bureau of Machinery Industry.
This Standard shall be under the jurisdiction of National Technical Committee
on Technical Drawings of Standardization Administration of China.
Drafting organizations of this Standard: Machinery Standardization Institute,
Chongqing Machine Manufacturing School, Dalian Bohai Riping Machine Tool
Co., Ltd.
Main drafters of this Standard: Qiang Yi, Yang Dongbai, Chen Shuguo, Hou
Ying, Huang Ju, Lai Jianguo.
Mechanical drawings - Representation of centre holes
1 Scope
This Standard specifies the representation of centre holes.
This Standard applies to standardized centre holes when it is not necessary to
show the exact form and structure in mechanical drawings. Centre holes other
than standardized centre holes may also refer to this Standard.
2 References
The following standards contain provisions which, through reference in this
Standard, constitute provisions of this Standard. At the time of publication, the
editions indicated are valid. All standards are subject to revision. The parties
who are using this Standard shall explore the possibility of using the latest
version of the following standards.
GB/T 145-1985 Center holes (validated in 1999)
GB/T 10609.4-1989 Technical drawings - Requirements for microcopying
(validated in 1999)
GB/T 14691-1993 Technical drawings - Lettering
GB/T 17450-1998 Technical drawings - Basic conventions for lines
3 Symbols of centre holes
3.1 Requirements
On technical drawings, generally there are three different requirements on
whether centre holes are remained in the finished part:
a) centre hole is required on the finished part;
b) centre hole may remain on the finished part;
c) centre hole shall not exist on the finished part.
3.2 Symbols