METHOD FOR MAKING SLEEVES Russian patent published in 1998 - IPC

FIELD: plastic metal working, namely manufacture of sleeves from coated sheets and strips used as capsules of detonators in mining industry, capsules of ignitors and building cartridges. SUBSTANCE: circular blank is punched from steel belt and it is drawn in die sets to sleeve by five steps until achieving ratio of its height h to inner diameter d at the end of each operation equal respectively: 0.5-1.6; 1.7-1.9; 2.6-2.8; 5.5-6.5; 9.0-10.5. Protective non-ferrous metal coat with thickness 1-5 micrometers is applied onto sleeve surface after first drawing operation at electric current density 0.2-0.5 A/ square dm and temperature 10-35 C for 40-60 min. EFFECT: enhanced efficiency. 1 cl, 2 tbl