metal there is therefore a benefit to annealing this material before the bending in fig2 if the material is thermoplastic then the deformed material should be heated after the bending of fig2 to 34 set 34 the plastic in the bent configuration referring to fig2 the surfaces walls and radii of the bulged portion are described using the numbers of fig1 these numbers are not shown on fig2 in order that the maximum clarity of the description of the movements of these surfaces be gained fig2 shows tube portions 12 and 14 after bending in the amount of angle 34 a 34 and the accommodations in the bulged area that have accommodated this angle of bend the inner radius area of the portion 30 i folds together by bending to a more acute angle radii 16 20 24 and 28 some bending of wall portions 18 22 and 26 will also occur the outer radius of the bend 30 0 shows radii 32 36 40 and 44 getting larger as walls 34 38 and 42 come to their new orientation in between these extremes intermediate bending of the bulged portion occurs when this bending to angle 34 a 34 takes place a metal material will again work harden helping to 34 set 34 the bend note that the minimum dimensions of the lengths of wall segments 18 34 20 38 and 26 42 depend on the angle 34 a 34 to which the tubes.