A first roll (20) and a second roll (40) of a roll forming device are provided with a plurality of stacked cutting blades (22, 122) and retainers (21, 121). The retainers (21, 121) pass through the stacked cutting blades (22, 122) and receive a first rotating shaft (16) and a second rotating shaft (18). Projections (21a, 121a) are formed on end portions of the retainers (21, 121). When the cutting blades (22, 122) are stacked, the projections (21a, 121a) control positioning operation of the cutting blades (22, 122). With this constitution, when the cutting blades (22, 122) are joined in a stacked state to the retainers (21, 121), the cutting blades (22, 122) in the stacking direction is controlled with the retainers (21, 121).

A first roll (20) and a second roll (40) of a roll forming device are provided with a plurality of stacked cutting blades (22, 122) and retainers (21, 121). The retainers (21, 121) pass through the stacked cutting blades (22, 122) and receive a first rotating shaft (16) and a second rotating shaft (18). Projections (21a, 121a) are formed on end portions of the retainers (21, 121). When the cutting blades (22, 122) are stacked, the projections (21a, 121a) control positioning operation of the cutting blades (22, 122). With this constitution, when the cutting blades (22, 122) are joined in a stacked state to the retainers (21, 121), the cutting blades (22, 122) in the stacking direction is controlled with the retainers (21, 121).

A method of manufacturing a metal mask includes calendering a metal material, so as to form a metal mask substrate, where the metal mask substrate includes a surface and a plurality of grooves formed in the surface, and the grooves all extend in a direction. The surface has at least one sampling region, while at least two grooves are distributed in the sampling region, where an average area ratio of the area of the grooves within the sampling region to the area of the sampling region ranges between 45% and 68%.

A method of manufacturing a metal mask includes calendering a metal material, so as to form a metal mask substrate, where the metal mask substrate includes a surface and a plurality of grooves formed in the surface, and the grooves all extend in a direction. The surface has at least one sampling region, while at least two grooves are distributed in the sampling region, where an average area ratio of the area of the grooves within the sampling region to the area of the sampling region ranges between 45% and 68%.