| 摘要 |
The mine roof plate comprises a rigid, sheet steel element of substantially uniform thickness having a domed section which reinforces the plate against distortion. The domed section is at least partially of generally quadrilateral configuration, having a substantially square base and defines an elevated section having an aperture therein circumscribed by a generally planar land surface. The periphery of the plate is of planar, rectangular configuration and disposed in spaced parallel relationship to the elevated section. The configuration of the domed section, in having right-angular corner portions, defines thereby reinforcing ribs, along the domed section, which terminate at the planar periphery of the plate.
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