| 摘要 |
An earthing device is described for a laminated worktable plate which includes a conductive surface layer, a supporting plate and an electrically highly conductive inner layer which is located between the surface layer and the supporting plate. The earthing device includes a first screw part (10) having a head which has a flat top (12) and a conical bottom (14) whose cone angle is considerably greater than 90 DEG , for example 140 DEG . The plate is provided with a cylindrical depression (42) which passes through the conductive surface layer, which is capable of resistance, but not through the highly conductive inner layer, and the first screw part (10) is pulled by means of its head, which is conical at the bottom, through a mating screw part (20) into this depression, until its top is flush with the top (52) of the plate. <IMAGE>
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