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This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 12362-2003 “Steel Die Forgings-Tolerance and machining allowances”. Compared with GB/T 12362-2003, except for editorial changes, the main changes are as follows:
- Replace the “Machine Machining Margin and Its Usage Principle” in the scope with “Machine Machining Remaining Level and Technical Content”, and change the “Structured Steel Forgings” to “Structural Steel Die Forgings” and replace “250kg” with “500kg”. (See Chapter 1, Chapter 1 of the 2003 Edition.)
- Remove "forgings that required additional manufacturing processes to be achieved" and "flat forged parts used only at ordinary level" (see 2.1 in 2003)
In the special case a) of 3.1.2, “In selecting tolerances, the mass of the forging is considered only the mass of the cylindrical part of diameter d and thickness t; if this special rule selects a tolerance less than that of 3.1.2 Tolerances selected by the rules are selected according to the general rules of 3.1.2” is added (see 3.1.2).
In the special case b) of 3.1.2, the “Where selecting the dimensional tolerances of the relevant features, the quality of the forgings only considers the mass of the cylinder with a diameter of d1 and a thickness of t1; if the tolerances chosen for this special rule are less than .2 Tolerances for general rules are based on the tolerances selected in 3.1.2 General rules (see 3.1.2) is added;
Remove “Where using coal-fired or secondary-fired heating, consider increasing the tolerance or margin appropriately, the value of which shall be determined through negotiation between the supply and demand sides” (see 3.1.6 of the 2003 edition).
Change "error tolerance" to "error" (see 3.2.4, 2003 version 3.2.4)
Change "deep tolerance" to "depth" (see 3.2.14, 2003 version 3.2.14)
The quality ranges in Table 1, Table 2, Table 3, Table 4, and Table 16 are revised and the query lines are added (see Table 1, Table 2, Table 3, Table 4, Table 16, Table 1, Table 2 of 2003 Edition), Table 3, Table 4, Table 16)
The aperture range in Table 15 is modified and the query line was added (see Table 15, Table 15 of the 2003 Edition).
This standard was proposed and is under the jurisdiction of the National Forging Standardization Technical Committee (SAC/TC74).
The previous versions of the standards replaced by this standard are:
- GB/T 12362-1990, GB/T 12362-2003.
Steel Die Forgings-Tolerance and Machining Allowance
1 Scope
This standard specifies the steel die forgings (hereinafter referred to as "forgings") tolerances and machining allowance levels and technical content.
This standard applies to die forging hammers, hot die forging presses, screw presses, flat forging machines and other forging equipment production of structural steel die forgings.
Other steel forgings can also be used as reference. This standard applies to forgings with a mass less than or equal to 500kg and a length (maximum size) less than or equal to 2500mm.
2 Level of Tolerances and Machining Allowances
2.1 The tolerance is divided into two levels: ordinary level and precision level.
Ordinary tolerances apply to forgings that meet the technical requirements of general die forging processes.
Precision tolerances apply to forgings with higher technical requirements and can be used for the full size of a forging and for local dimensions.
2.2 The Machining Allowance is Only One Level.
3 Technical Content
3.1 The main factors to determine forging tolerance and machining allowance
3.1.1 Forging Mass mf
Forging quality are estimated according to the following procedure:
The basic dimensions of the part drawing → Estimate the machining allowance → Draw the forging drawing → Estimate the forging quality, and determine the tolerance and machining allowance according to this quality check table.
3.1.2 Forging Shape Complex Factor S
The forging complex shape factor is the ratio of the forging mass mf to the corresponding forging external shell mass mN, see Equation (1):
S=mf/mN (1)
The forging profile containment mass mN is the calculated mass of the cylinder or cuboid containing the largest profile of the forging as the entity, and is calculated according to formula (2) or formula (3):
a) Round forgings (Figure 1)
mN=1/4·π·d2·h·ρ (2)
Where:
ρ——Steel density(7.85g/cm3)
Figure 1 Round Forgings
b) Non-circular forgings (Figure 2)
mN=l·b·h·ρ (3)
Figure 2 Non-circular Forgings
According to the size of S value, forging complex shape factor is divided into 4 levels:
S1 level (simple): 0.63
Foreword i
1 Scope
2 Level of Tolerances and Machining Allowances
3 Technical Content
Annex A (Informative) Forging Tolerance Application Example
ICS 77.140.85
J 32
中华人民共和国国家标准
GB/T 12362-2016
代替GB/T 12362-2003
钢质模锻件
公差及机械加工余量
Steel die forgings-Tolerance and machining allowance
2016-12-13发布 2017-07-01实施
中华人民共和国国家质量监督检验检疫总局
中国国家标准化管理委员会
发布
前言
本标准按照GB/T 1.1-2009给出的规则起草。
本标准代替GB/T 12362-2003《钢质模锻件 公差及机械加工余量》，与GB/T 12362-2003相比，除编辑性修改外，主要变化如下：
——将范围中“机械加工余量及其使用原则”改为“机械加工余量等级和技术内容”，将“结构钢锻件”改为“结构钢模锻件”，将“250kg”改为“500kg”（见第1章，2003年版的第1章）；
——删除了“但需要采取附加制造工艺才能达到的锻件”和“平锻件只采用普通级”（见2003年版的2.1）；
——在3.1.2特殊情况a）中，增加了“在选取公差时，锻件质量只考虑直径为d、厚度为t的圆柱体部分的质量；如果此特殊规则选取的公差小于按3.1.2-般规则选取的公差，则按3.1.2一般规则选取公差”（见3.1.2）；
——在3.1.2特殊情况b）中，增加了“在选取相关特征的尺寸公差时，锻件质量只考虑直径为d1、厚度为t1的圆柱体部分的质量；如果此特殊规则选取的公差小于按3.1.2一般规则选取的公差，则以3.1.2一般规则选取的公差为准”（见3.1.2）；
——删除了“采用煤加热或二火加热时，可考虑适当增大公差或余量，其数值由供需双方协商确定”（见2003年版的3.1.6）；
——将“错差公差”改为“错差”（见3.2.4，2003年版的3.2.4）；
——将“深度公差”改为“深度”（见3.2.14，2003年版的3.2.14）；
——修改了表1、表2、表3、表4、表16中的质量范围并增加查询行（见表1、表2、表3、表4、表16，2003年版的表1、表2、表3、表4、表16）；
——修改了表15中的孔径范围并增加查询行（见表15，2003年版的表15）。
本标准由全国锻压标准化技术委员会（SAC/TC74）提出并归口。
本标准主要起草单位：东风锻造有限公司、北京机电研究所。
本标准主要起草人：吴玉坚、吴听松、魏巍、金红、赵业勤、陈文敬、程琛文。
本标准所代替标准的历次版本发布情况为：
——GB/T 12362-1990、GB/T 12362-2003。
钢质模锻件公差及机械加工余量
1范围
本标准规定了钢质模锻件（以下简称“锻件”）的公差及机械加工余量等级和技术内容。
本标准适用于模锻锤、热模锻压力机、螺旋压力机、平锻机等锻压设备生产的结构钢模锻件。其他钢种的锻件亦可参照使用。本标准适用于质量小于或等于500kg，长度（最大尺寸）小于或等于2500mm的锻件。
2公差及机械加工余量等级
2.1本标准中公差分为两级：普通级和精密级。
普通级公差适用于一般模锻工艺能够达到技术要求的锻件。
精密级公差适用于有较高技术要求的锻件。精密级公差可用于某一锻件的全部尺寸，也可用于局部尺寸。
2.2机械加工余量只采用一级。
3技术内容
3.1确定锻件公差和机械加工余量的主要因素
3.1.1锻件质量mf
锻件质量的估算按下列程序进行：
零件图基本尺寸→估计机械加工余量→绘制锻件图→估算锻件质量，并按此质量查表确定公差和机械加工余量。
3.1.2锻件形状复杂系数S
锻件形状复杂系数是锻件质量mf与相应的锻件外廓包容体质量mN之比，见式（1）：
S=mf/mN （1）
锻件外廓包容体质量mN为以包容锻件最大轮廓的圆柱体或长方体作为实体的计算质量，按式（2）或式（3）计算：
a）圆形锻件（图1）
mN=1/4·π·d2·h·ρ （2）
式中：
ρ——钢材密度（7.85g/cm3）。
外廓包容体
外廓包容体
图1圆形锻件
b）非圆形锻件（图2）
mN=l·b·h·ρ （3）
外廓包容体
外廓包容体
图2非圆形锻件
根据S值的大小，锻件形状复杂系数分为4级：
S1级（简单）：0.63
GB/T 12362-2016 引用如下标准： |
GB/T 12362-2016被如下标准引用：
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