GB/T 37676-2019 English PDF (GBT37676-2019)

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GB/T 37676-2019: High speed precision hot upsetting forgings -- Technological specification
GB/T 37676-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.85
J 32
High Speed Precision Hot Upsetting Forgings -
Technological Specification
ISSUED ON: JUNE 4, 2019
IMPLEMENTED ON: JANUARY 1, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative References ... 4 
3 Terms and Definitions ... 5 
4 Design Principles ... 5 
High Speed Precision Hot Upsetting Forgings -
Technological Specification
1 Scope
This Standard stipulates the technological specification of high speed precision hot
upsetting forgings (hereinafter referred to as “forgings”), including general principles,
determination of technological parameters, preparation of forging billets, billet heating,
requirements of moulds and selection of equipment.
This Standard is applicable to the technological design for steel precision forgings
which adopt hot upsetting for molding, and with the production pace of 50 PCS/min
and above, the mass of below 7.5 kg, and the outer diameter of not more than 180 mm.
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 699 Quality Carbon Structural Steels;
GB/T 700 Carbon Structural Steels;
GB/T 1299 Tool and Mould Steels;
GB/T 1591 High Strength Low Alloy Structural Steels;
GB/T 3077 Alloy Structure Steels;
GB/T 5216 Structural Steels with Specified Hardenability Bands;
GB/T 8541 Terminology of Forging and Stamping;
GB 13318-2003 General Rules for Safety and Environmental Conservation of Forging
Production;
GB/T 15712 Micro-alloyed Medium Carbon Steels;
GB/T 18254 High-carbon Chromium Bearing Steel;
GB/T 28417 Carbon Bearing Steel;
4.1.7 Mould parts that contact forgings shall be cooled down. Generally speaking, the
cooling medium of moulds shall select water. Avoid directly spraying forgings with the
cooling medium.
4.1.8 In terms of forgings with a relatively large amount of deformation, proper
lubricating agent should be added to the cooling medium.
4.1.9 The replacement of moulds should be conducted in sets.
4.1.10 Post-forging afterheat should be utilized in the thermal treatment of forgings.
4.1.11 During the whole production process, consider adopting anti-collision measures
for forgings.
4.1.12 The operating environment shall comply with the requirements in 5.2 in GB
13318-2003; personnel shall satisfy the requirements in 10.2 in GB 13318-2003; safety
and environmental protection technological measures shall comply with the
requirements in Chapter 9 in GB 13318-2003.
4.2 Determination of Technological Parameters
4.2.1 Deformation temperature
4.2.1.1 Deformation temperature shall be within the Austenite zone, which is above the
recrystallization temperature. In order to avoid over-heating and over-burning
phenomena, heating temperature should be within 1,150 °C ~ 1,280 °C. Specifically
speaking, heating temperature of bearing steel should not exceed 1,180 °C. On the
premise of thorough cooling of moulds, the heating temperature should approach the
upper limit.
4.2.1.2 After forging, the temperature should be quickly cooled down to below AC1, so
as to avoid grain growth.
4.2.1.3 When afterheat is utilized for thermal treatment, the final forging temperature
of forgings shall satisfy the requirements of the subsequent thermal treatment.
4.2.2 Degree of deformation
4.2.2.1 Degree of deformation of the various stations shall avoid large grains caused
by final accumulative deformation.
4.2.2.2 The selection of the degree of deformation shall consider the influence of
deformation mode on allowable deformation.
4.2.3 Deformation force
Numerical value simulation should be adopted to analyze and calculate deformation
force, or, nomograph or empirical formula may also be adopted for calculation. 4.2.1.7
4.4 Billet Heating
4.4.1 Billet heating shall adopt the mode of integral-bar induction heating. Furthermore,
there shall be temperature detection; high and low temperature alarm and shutdown
functions.
4.4.2 The selection of the specification of the sensor shall match with the diameter of
the heating billets, so as to avoid low efficiency of heating.
4.4.3 The billet feeding pace shall comprehensively consider factors like billet
dimensions, heating temperature and forging equipment, etc. It shall be on the premise
that the heating temperature of billets shall evenly reach the technological requirement.
4.5 Requirements of Mould
4.5.1 The precision of moulds shall satisfy precision requirements of forgings, such as:
dimensions, shape and position tolerances, etc.
4.5.2 Convex mould, concave mould and ejector pole should adopt nitridation for
surface treatment, so as to enhance the surface hardness and abrasive resistance of
moulds. The surface roughness value of moulds shall be not more than Ra0.8 m.
4.5.3 Concave mould and ejector pole should be designed into hollow structure, so
that the coolant can cool down the concave mould.
4.5.4 Convex mould and concave mould of closed molding station shall have a guide
structure. The bilateral matching clearance should be controlled within 0.10 mm ~ 0.30
mm.
4.6 Selection of Equipment
4.6.1 Equipment’s force-stroke curve and energy shall satisfy the requirements of the
force-stroke curve and deformation work of the molding of forgings.
4.6.2 Equipment precision shall comply with the relevant stipulations in GB/T 29532.
4.6.3 The selection of equipment shall consider the actual output demand for forgings,
the load of the various stations, the allowable eccentric load and the cost of production,
etc.
4.6.4 Equipment shall be equipped with material head and material tail automatic
detection and rejection system. The requirements for the precision, stability and
reliability of the mechanical arm transmission system; the efficiency of the cooling
system for moulds; the internal cooling of moulds; the quick replacement of moulds
and the reliability of the ejecting device shall be considered.
4.6.5 An automatic production line should be built, which mainly includes feed