为实现无损在线探测缸盖内部热裂纹,提出一种基于红外热成像技术,由缸盖表层温度直接判断其内部热缺陷的新方法。以某型柴油机缸盖为研究对象,分析了缸盖的传热机理,结合缸盖温度场的三维分布,确定了其内部易产生热裂纹的部位,并对裂纹结构进行了加工模拟。构建缸盖温度场检测台架,对正常结构缸盖与裂纹缸盖开展了外部特征区域温度场的检测。结果表明,在缸盖传热边界一定的情况下,缸盖表层温度场的变化能直接反映缸盖内部热裂纹缺陷,具体表现为传热受阻的左表面特征区域最高温度值降低,而其他特征表面由于传热量的增强使得表面上的温度升高,这与缸盖实际的传热规律相符。 In order to realize the non-destructive on-line detection of the hot crack in the cylinder head, a new method based on the infrared thermography is proposed to directly judge the internal thermal defect from the cylinder head surface temperature. Taking a cylinder head of a diesel engine as the research object, the heat transfer mechanism of the cylinder head is analyzed. Combined with the three-dimensional distribution of the temperature field of the cylinder head, the site where hot cracks easily occur is determined and the crack structure is simulated. Construction of cylinder head temperature field test bench, the normal structure of the cylinder head and cracked cylinder head carried out the detection of the external characteristic temperature field. The results show that the variation of the temperature field in the cylinder head surface can directly reflect the thermal crack defects in the cylinder head under the condition that the heat transfer boundary of the cylinder head is constant. The maximum temperature value of the left surface characteristic region with the blocked heat transfer decreases, while the other characteristics Surface due to heat transfer enhancement makes the surface temperature, which is consistent with the actual heat transfer cylinder head law.