Volute wrapper sheet forming method and mold thereof

The invention provides a volute wrapper sheet forming method. The method comprises the following steps that sheet cutting is carried out, and folding edges are formed; a process gap is selected as a turnover gap, a volute wrapper sheet is divided into a first curve portion, a second curve portion and a third curve portion, and the first curve portion and the second curve portion are formed through a first mold; the third curve portion is formed through a second mold. According to the volute wrapper sheet forming method, the approximately-closed spiral curve of the volute wrapper sheet is divided into the three continuous curve portions, the curve portions at the two ends are firstly bent and formed at a time, then the middle curve portion is bent and formed at a time, and therefore the complete spiral curve is formed. The mold design is simple, the production period is short, labor intensity is reduced, machining difficulty is lowered, and work efficiency is improved. In the production process, the volute wrapper sheet is not prone to deforming, and product quality is stable. The invention further provides a mold for the method.