Abstract: A method of eliminating corrugation in central umbrella cover, being made of a plain weave cloth, in which the weft has no stretchability, while the warp has a slight stretchability; before the umbrella cloth being cut into an umbrella cover, the umbrella cover and the main rib are set a different angle of ten degrees; the tail end of the main ribs and the sewing points of the umbrella cloth are not fallen on the parallel line of the warp or the weft; from the sewing points to the central part of the ribs, there are different length so as to balance the tension of various stretch points; the edge of the umbrella cover is cut out and sewed properly so as to provide suitable corrugation-proof. When the umbrella is opened, the central portion of the umbrella cover would not have corrugation and looseness because of the main ribs having a slight curvature, and the oblique weave mesh able to balance the stretched tension.

Abstract: A method for forming a cover of an umbrella including preparing several pieces of cloth, clamping the perimeters of the cloth and pulling the cloth downward against a lower mold having a convex shape, heating the lower mold in order to soften the cloth, moving an upper mold downward to clamp the cloth, heating the lower mold again in order to further increase the temperature of the lower mold so that the cloth can be hot-pressed, cooling the lower mold, removing the cloth, and cutting the perimeter of the cloth so as to form the cover of the umbrella.