| 摘要 |
A nut retaining formation is made in the wall of a thermoplastic (metal or plastic) article, such as the flange of a floor drain fitting, by a one step die forming operation. The formation has a cavity in the intermediate thickness of the flange, the height of the cavity being such that a screw threaded apertured nut is a close sliding fit therein. A runway formation provides access to the cavity from the top surface of the flange at one side thereof, the nut being slidable down the runway into the cavity. An aperture through the top surface provides access for a screw to be inserted into the cavity to engage a nut positioned therein. The top and bottom walls of the cavity are formed by discontinuous nut retaining formations in the top part and bottom part of the wall thickness, surrounding the screw receiving aperture. The formations in the top part of the wall thickness align vertically with gaps or separations between the nut retaining formations in the bottom part of the wall thickness, and the nut retaining formations in the bottom part of the wall thickness align vertically with gaps or separations between the nut retaining formations in the top part of the wall thickness. By this means, the formations and nut receiving cavity can be stamped in the wall by a one step pressing operation between a pair of co-operating dies, approaching from above and below the wall, and arranged to overlap one another in the pressing operation partially but not completely.
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