| 摘要 |
An ionization-type smoke detector having a heat-resistant metal case forming the outer electrode and, with an attached rear cover, enclosing the upper portion of an insulating base board. The heat-resistant case includes a cylindrical portion surrounding an outer ionization chamber, a rectangular quadratic portion surrounding the insulating base board, and a planar stepped portion connecting the quadratic prism portion and the cylindrical portion. In the method of forming the case, a metal plate is first subjected to a drawing process to form a cylindrical cup-shaped recess that will ultimately become the cylindrical portion of the case. The remainder of the plate includes a rectangular central section and four integral rectangular outer sections extending along each of the four sides of the central section. The rectangular outer sections are then bent upwardly to form the rectangular quadratic prism portion, and the adjacent side edges of the four rectangular four sections are secured to each other by studs that may also be used to connect the case to its cover.
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