Lubrication of tube in cold pilgering

•We studied lubrication of tube in cold pilgering.•A calculation method of oil film thickness using Reynolds equation was proposed.•The calculation results revealed significant effects of tool design and rolling speed.•The cold pilgering test results proved that the method was valid.•The method assists the selection of appropriate operation conditions.

A new method of evaluating the lubrication state of a tube in cold pilgering has been studied. A method of calculating the oil film thickness in a bite area on both the outer and inner sides of a tube using the Reynolds equation was proposed. The calculation results revealed that the effects of the tool design, rolling speed, and feed rate on the oil film thickness were significant. Cold pilgering tests were performed on zirconium alloy tubes, including measurement of the oil film thickness using laser equipment and observation of the surface characteristics of tubes. The test results proved the validity of the proposed method. The method is expected to assist the selection of appropriate operation conditions in cold pilgering.