JB/T 51125-1999
Internal combustion engines - Cylinder heads - Product quality grading (Internal use)
内燃机 气缸盖 产品质量分等（内部使用）
Catalogue
前言 → 1 范围 → 2 引用标准 → 3 质量指标 → 4 检验方法 → 5 检验规则 Foreword → 1 Scope → 2 Normative References → 3 Quality Indicators → 4 Inspection Methods → 5 Inspection Rules
Scope
This standard specifies the product quality indicators, inspection methods, and inspection rules for cast iron and cast aluminum cylinder heads (hereinafter referred to as cylinder heads) of reciprocating internal combustion engines with cylinder diameters less than or equal to 200 mm. This standard applies to the inspection and evaluation of the product quality of internal combustion engine cylinder heads.
本标准规定了气缸直径小于或等于200 mm 的往复式内燃机铸铁、铸铝气缸盖（以下简称气缸盖）产品质量指标、检验方法、检验规则。本标准适用于内燃机气缸盖产品质量的检验和评定。
Normative References
Keywords
Application Summary AI generated
Manufacturers of internal combustion engines and quality inspection agencies use this standard to grade and inspect cylinder head products. It helps users evaluate and select cylinder heads at different quality levels by defining three grades: qualified, first-class, and superior. This standard is important because it unifies quality requirements for cylinder heads, ensuring product reliability and interchangeability.
内燃机制造商和质检机构使用本标准来对气缸盖产品进行质量分级和检验。它通过设定合格品、一等品和优等品三个等级，帮助用户评估和选择不同质量水平的气缸盖。该标准的重要性在于它统一了气缸盖的质量要求，确保了产品的可靠性和互换性。
AI Summary AI generated
This standard applies to the quality grading of cast iron or cast aluminum cylinder heads for reciprocating internal combustion engines with cylinder diameters ≤200 mm. It classifies products into three grades: qualified, first-class, and superior, specifying quality indicators such as material mechanical properties, dimensional tolerances, geometric tolerances, surface roughness, casting defects, and sealing performance. Corresponding inspection methods and sampling inspection rules are provided. This standard offers a unified basis for quality control and grade evaluation of internal combustion engine cylinder heads.
本标准适用于气缸直径≤200mm的往复式内燃机铸铁或铸铝气缸盖的质量分等。标准将产品分为合格品、一等品和优等品三个等级，规定了材料力学性能、尺寸公差、形位公差、表面粗糙度、铸造缺陷及密封性等质量指标，并给出了相应的检验方法和抽样检验规则。该标准为内燃机气缸盖的质量控制和等级评定提供了统一依据。
Key Sentences extracted from text
本标准规定了气缸直径小于或等于200 mm 的往复式内燃机铸铁、铸铝气缸盖产品质量指标、检验方法、检验规则。
气缸盖产品按其不同质量指标定为合格品、一等品和优等品三个等级。
灰铸铁气缸盖力学性能分级按表1 规定。
产品应经密封性试验无渗漏。
样本经全数检查后，当样本中各类不合格的不合格项数小于或等于优等品的Ac 值时，评被检产品为优等品。
This standard specifies the product quality indicators, inspection methods, and inspection rules for cast iron and cast aluminum cylinder heads of reciprocating internal combustion engines with cylinder diameters less than or equal to 200 mm.
Cylinder head products are classified into three grades: qualified product, first-class product, and superior product, according to their different quality indicators.
The mechanical property grading of gray cast iron cylinder heads is specified in Table 1.
The product shall undergo a sealing test without leakage.
After complete inspection of the sample, when the number of nonconforming items of each type in the sample is less than or equal to the Ac value for superior product, the inspected product is rated as superior product.
Standard Timeline
Changes from replaced version:
- 仅对原标准作了编辑性修改，主要技术内容没有变化
- Only editorial modifications were made to the original standard; the main technical content remains unchanged.