PIERCING MACHINE, MANDREL BAR, AND METHOD FOR MANUFACTURING SEAMLESS METALLIC TUBE USING SAME

A piercing machine is provided that can suppress a temperature difference between a fore end portion and a rear end portion of a hollow shell after piercing-rolling or after elongating rolling. A mandrel bar (3) of a piercing machine includes: a bar body (31); a coolant channel (34) formed inside the bar body (31) and through which a coolant flows; an inner surface cooling mechanism (340) which is disposed in a cooling zone (32) and is connected to the coolant channel (34) and which, during piercing-rolling or during elongating rolling, ejects the coolant to outside of the bar body (31) to cool an inner surface portion of a hollow shell (50) inside the cooling zone (32); and an inner surface damming mechanism (350) which is disposed adjacent to the cooling zone (32) on a rearward side of the cooling zone (32) and which, during piercing-rolling or during elongating rolling, suppresses the coolant that is ejected to outside of the bar body (31) from contacting the inner surface portion of the hollow shell (50) that is positioned rearward of the cooling zone (32).