| 摘要 |
A close for a hole in a wall includes a cover placed over the hole, apertures extending through the cover and the wall, hollow cylindrical bolts lodged in the apertures with flanged open ends engaged with the cover and closed ends protruding from the wall, and an expansion tool operable to exert radial force against the lateral wall of a bolt and axial force against its closed end to expand it. - A process for securing a cover to a hole is also claimed.
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