20厘米=2分米，
[3.14×2×6+3.14×（2÷2）²×2]×50
=[3.14×12+3.14×1²×2]×50
=[37.68+6.28]×50
=43.96×50
=2198（平方分米）．
答：至少需2198平方分米铁皮．