Fabrication of tooling for hot working and cold pilgering for the manufacture of seamless tubes for nuclear industry

Full text: Zirconium based alloys are used for the manufacture of fuel tubes, pressure tubes, calandria tubes and other components of Pressurized Heavy Water Reactors. The process of manufacturing of these Zirconium alloy seamless tubes can be broadly divided into hot working and cold working. Hot working involves extrusion, expansion, rolling etc. and cold working processes followed are pilgering, drawing, swaging, etc. Toolings play important role in all fabrication stages. Hot extrusion tools are subjected to abrupt changes in temperature, variable stress and abrasion. Extrusion tools are used in different forms such as dies, mandrels, dummy blocks, stem and die backers etc. Pilgering is the main process in cold deformation of extruded blanks. Tool dimensions and profiles play an important role in pilgering of Zirconium alloy tubes. This paper attempts to specify the critical steps involved in the production of tools required for hot and cold working operations. Effect of heat treatment on quality of tools is also elaborated. Introduction of special heat treatment to improve the life of tools and utilization of machine have been also emphasized