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