To prevent a failure of uneven thickness in a solution film forming method.
A decompression chamber 50 is formed in the shape of a box by each seal plate 152-258. Partition plates 160-163 are arranged bilaterally symmetrically in a hollow part 150a. A windshield 170 is installed to make the back 170c and the front end of each seal plate 152-160 be fixed. A groove 175 is formed in the bottom face 170b to extend in the width direction of a casting bead 200. Projections 177a-177c are formed on the bottom face 170b by the groove 175. By adjusting the shape, size, and forming pitch of the groove 175 formed in the windshield 170, the shapes of the projections 177a-177c, etc., the value of Q1/Q2 is kept approximately constant between 1/100 and 1/4. Q1 is the flow rate of air A1 flowing into a decompression zone through the space between the bottom face 170b and a circumferential face 72, and Q2 is the flow rate of air A2 near an opening 150c flowing into the hollow part 150a.
OCHIAI AKINORI
KATO AKIFUMI
Shigeru Iijima
Kobayashi Hideyoshi