GB/T 5279.2-1997 Countersunk head screws Part 2: Cross recess insertion depth

This standard specifies the cross slot insertion depth for countersunk head screws with thread specifications of M1.6~M10 and ST2.2~ST9.5 and performance levels 4.8, 8.8, and 9.8. There are two series, 1 and 2 (deep and shallow respectively). GB/T 5279.2-1997 Countersunk head screws Part 2: Cross slot insertion depth GB/T5279.2-1997 Standard download decompression password: www.bzxz.net

GB/T 5279.2-1997
This standard is equivalent to the international standard ISO7721-2:1990 "Countersunk head screws GB/T5279 The general title is "Countersunk head screws", including the following parts: Part 2: Cross recess insertion depth".
Part 1: Head shape and measurement (GB/T527985 will be revised according to the revised version of ISO7721:1983 and published according to GB/T 5279.1);
-Part 2: Cross recess insertion depth.
Appendix A of this standard is a prompt appendix.
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fasteners. This standard is drafted by the Mechanical Science Research Institute of the Ministry of Machinery Industry. 357
GB/T5279.2
--1997
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The development of international standards is carried out through ISO technical committees. Each member body can also participate in the committee if it is interested in the project carried out by a technical committee. Governmental and non-governmental international organizations related to ISO can also participate in this work. ISO has close ties with the International Electrotechnical Commission (IEC) in electrotechnical standardization. The draft international standards adopted by the technical committee are distributed to all member bodies for voting. The formal publication of international standards requires at least 75% of the member bodies to vote in favor.
International Standard ISO7721-2 was developed by ISO/TC2 Fastener Technical Committee. The general title of ISO7721 is "Countersunk Screws", which includes the following parts: Part 1: Head shape and measurement;
-Part 2: Cross recess insertion depth.
Appendix A of this standard is an informative appendix.
GB/T 5279.2-1997
ISO Introduction
The insertion depth of the cross recess of a countersunk screw must meet two requirements. That is, for a given head size, conflicting requirements must be met.
First, sufficient head strength is required to achieve the proof load and breaking load specified in each performance level. A shallow cross recess can increase the head strength. On the other hand, the screwing performance of the screw must also be satisfactory, which can only be achieved with a sufficiently deep cross recess. ISO7721-2 was formulated to seek a comprehensive solution to meet these two requirements, and the solution should be as far-sighted as possible.
This part of ISO7721 specifies a deep cross recess for low-strength countersunk screws, which can achieve good screwing performance and sufficient head strength. This result will be used in ISO7046-1 (see Annex A). For higher-strength screws, sufficient head strength can only be achieved with a shallower cross recess insertion depth. If this type of screw also requires good screwing performance, then, under the condition of a universal head shape, a shoulder has to be added under the head to ensure sufficient head strength and a large insertion depth.
This comprehensive solution is the only way to achieve international level agreement at present, except for the different interchangeability of the head shape of cross recessed countersunk screws. 359
1 Scope
National Standard of the People's Republic of China
Countersunk flat head screws-Part 2: Penetration depth of cross recessesGB/T 5279.2—1997
idt ISO 7721-2:1990
This standard specifies the insertion depth of the cross recess of countersunk flat head screws with thread specifications of M1.6~M10 and ST2.2~ST9.5 and performance levels of 4.8, 8.8, and 9.8, with two series 1 and 2 (deep and shallow respectively). 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB944.1-85 Cross recess for screws
GB5276-85 Fasteners Bolts, screws, studs and nuts Dimension codes and markings GB5279-85 Countersunk screws Head shape and measurement 3 dimensions
The applicable range of the cross recess insertion depth is specified in Table 1. Different head under types (see Figures 1 and 2) are given to achieve sufficient head strength. Both types should meet the head shape specified in GB5279. Note: The size code and marking are in accordance with GB-5276. IP
Figure 1 Screws with shoulder under the head
Approved by the State Administration of Technical Supervision on August 5, 1997360
amx=2P
Figure 2 Screws without shoulder under the head
Implemented on April 1, 1998
Thread specification
Scope of applicationWww.bzxZ.net
Insertion depth 2
GB/T5279.2-1997
Table 1 Dimensions
Cross slot
Series 1 (deep)|| tt||Insertion depth 2)
Screws without shoulder under the head:
Self-tapping screws, wood screws, 4.8 grade screws
Screws with shoulder under the head:
8.8 grade and 9.8 grade screws, self-tapping and self-cutting screws, self-tapping locking screws
1) Cross slot shall be in accordance with GB944.1;
2) Measurement of insertion depth shall be in accordance with GB944.1: 3) As specified for steel screws, the applicable scope for other materials shall be selected by the manufacturer. H-type
Insertion depth?
Series 2 (shallow)
Insertion depth 2
Screws without shoulder under the head:
8.8 grade screws
Self-tapping locking screws
Self-tapping and self-cutting screws,
should be heat treated
GB819-85 cross recessed countersunk head screws 1;
GB/T819.2--1997
GB/T5279.2--1997
Appendix A
(Suggestive Appendix)
Part 2: Steel 8.8, stainless steel A2-70 and non-ferrous metal CU2 or cross recessed countersunk head screws
1) will be revised according to ISO7046-1:1994 and published according to GB/T819.1. 362
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