According to the present invention, {HEAD ~ the constructions} and shapes of {TAIL ~ the welded portions} are simplified 
of
According to the present invention , { HEAD ~ the constructions } and shapes of { TAIL ~ the welded portions } are simplified
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH