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GB/T 972-2008 PDF in English


GB/T 972-2008 (GB/T972-2008, GBT 972-2008, GBT972-2008)
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Standards related to: GB/T 972-2008

GB/T 972-2008: PDF in English (GBT 972-2008)

GB/T 972-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.100.50
J 41
Replacing GB/T 972-1994
Thread rolling flat dies
搓丝板
ISSUED ON: JUNE 03, 2008
IMPLEMENTED ON: JANUARY 01, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Type and size of thread rolling flat dies ... 4
4 Technical requirements ... 10
5 Marking and packaging ... 11
Thread rolling flat dies
1 Scope
This Standard stipulates the basic requirements for the type and size, profile size and
deviation, technical requirements, marking and packaging of thread rolling flat dies for
general purpose metric screw threads.
This Standard applies to thread rolling flat dies for processing general purpose metric
screw threads (GB/T 192~193, GB/T 196~197). Thread rolling flat dies are divided into
three precision grades: grade 1, grade 2 and grade 3. Grade 1 applies to the processing
of external threads with tolerance grades 4 and 5; grade 2 applies to the processing of
external threads with tolerance grades 5 and 6; grade 3 applies to the processing of
external threads with tolerance grades 6 and 7.
2 Normative references
The terms in the following documents become the terms of this Standard by reference
to this Standard. For dated references, all subsequent amendments (not including errata
content) or revisions do not apply to this standard. However, parties to agreements that
are based on this Standard are encouraged to study whether the latest versions of these
documents can be used. For undated references, the latest edition applies to this
Standard.
GB/T 192, General purpose metric screw threads - Basic profile (GB/T 192-2003,
ISO 68-1:1998, MOD)
GB/T 193, General purpose metric screw threads - General plan (GB/T 193-2003,
ISO 261:1998, MOD)
GB/T 196, General purpose metric screw threads - Basic dimensions (GB/T 196-
2003, ISO 724:1993, MOD)
GB/T 197, General purpose metric screw threads - Tolerances (GB/T 197-2003, ISO
965-1:1998, MOD)
3 Type and size of thread rolling flat dies
3.1 The type and size of thread rolling flat dies shall be as specified in Figure 1, as well
as in Table 1, Table 2 and Table 3. The installation angle of the thread rolling flat dies
for processing screw threads of d≤6 mm can also be made into 90°.
The thread rolling flat die of coarse pitch thread -- nominal diameter of processed thread
8 mm, pitch 1.25 mm, width 50 mm, fixed thread rolling flat die length 110 mm,
precision grade 2, thread profile A: Thread rolling flat die AM8×50/110-2 GB/T 972-
2008
The thread rolling flat die of fine pitch thread -- nominal diameter of processed thread
8 mm, pitch 1.00 mm, width 50 mm, fixed thread rolling flat die length 110 mm,
precision grade 2, thread profile A: Thread rolling flat die AM8×1×50/110-2 GB/T 972-
2008
Thread rolling flat dies for left screw threads shall be marked with “LH” after the
precision.
4 Technical requirements
4.1 The surface of the thread rolling flat die must be free of cracks, nicks, rust, grinding
burns and other defects that affect the performance.
4.2 The thread rolling flat die is made of 9SiCr or Cr12MoV alloy tool steel. The
uniformity of carbides of Cr12MoV is not more than grade 3.
4.3 The deviation of dimensions LD, LG, and B shall be h14. The width difference
between the fixed thread rolling flat die and the movable thread rolling flat die in a pair
of thread rolling flat dies shall not be greater than 0.1 mm.
4.4 The surface roughness of the thread rolling flat dies is not greater than:
-- Thread profile surface: Rz 6.3 μm;
-- Supporting surface, device surface: Ra 0.8 μm.
4.5 The hardness of the working part of the thread rolling flat dies is 59HRC~62HRC;
there shall be no decarburization and lower hardness on the working surface.
4.6 For the parallelism tolerance OF the intersection line between the plane
perpendicular to the supporting surface of the thread rolling flat die and the crest plane
TO the supporting surface, the width direction shall be in accordance with Table 5, and
the length direction shall be in accordance with Table 6. When inspecting the
parallelism of the crest of the thread rolling flat die to the supporting surface, the first
complete profile on both sides of the width direction can be ignored. When inspecting
the parallelism between the crest of the movable thread rolling flat die and the
supporting surface, the range of the two ends of the length direction of the thread rolling
flat die equal to the length (L) of the fixed thread rolling flat die’s pressed part can be
ignored.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.