| 摘要 |
<P>PROBLEM TO BE SOLVED: To manufacture a circular hood of a ventilator for ventilation in an inexpensive manner by using a small man-hours, and to improve its ventilation efficiency by eliminating distortion of a ventilation hole. <P>SOLUTION: The circular hood 3 of the ventilator for ventilation connected to a terminal of a ventilation duct is integrally formed as a flange part 7 and a shell part 8 in a semi-spherical shape by draw forming of a metal plate. After the draw forming of the circular hood 3, many ventilation holes 1 are formed on the shell part 8. The ventilation holes are formed by punching a punch pin to a die on an axial line which passes through the spherical center of the shell part 8. <P>COPYRIGHT: (C)2004,JPO |
