吊重法测蒸汽膜厚度(一)

Measurement of the Thickness of Vapor Blanket by Floating Weighing Method(一)

经过分析对比,提出了用蒸汽膜对试样的上浮力计算蒸汽膜厚度的蒸汽膜厚度测量法。确定了适合的试样。选用电子吊秤测量吊重。以匀速冷却液和60SN基础油作为冷却介质。试验中用两部摄像机分别记录了试样表面状况和吊重变化。用试验结果计算出试样温度在600℃附近时,在匀速冷却液中蒸汽膜厚度为0.2 mm,而在60SN基础油中蒸汽膜厚度为0.1 mm。试验结果验证了蒸汽膜随试样温度降低而减薄的变化规律。确定了蒸汽膜厚度,诱导锥的最低高度和隔离堤的最大缝隙也就确定了下来。用测算出的蒸汽膜厚度值解释了淬火介质的冷却特性曲线上油性介质在蒸汽膜阶段的冷却速度比水性介质的约大一倍的原因。

A floating weighing method is proposed for the measurement of the ket. Specimens suitable for the proposed measurement are determined. An el thickness of the vapor blanectronic hanging balance is used. The constant cooling rate quenchant and the 60SN basic oil are used as the cooling media. The surface condition and the change in the readings of the hanging balance are recorded by two video cameras respectively. Experimental results show that the thickness of the vapor blanket in the constant cooling rate quenchant was O. 2 mm when the specimen temperature was around 600 ℃ ,whilst the thickness of the vapor blanket in the basic oil was 0.1 mm. The thickness of the vapor blanket is reduced with decreasing temperature was proved by the results. By determining the thickness of the vapor blanket, the minimum height of the derivational cone and maximum gap of the isolation bank were also determined. The reason why the cooling rate for oils is doubted as compared to the aqueous quenchants during the vapor blanket cooling stage was explained.