| 摘要 |
A forward and reverse expanding type expansion screw has a bolt, a nut, a forward expanding plug, a retaining tapered ring, and a backward expanding plug. By inserting the bolt through the forward expanding plug, the retaining tapered ring and the reverse expanding plug in order, the expansion screw can be inserted into a wall hole, the bolt can be driven to lock to the nut, the reverse expanding plug first expanding in the reverse direction by a pushing effect caused by the retaining tapered ring, and then the forward expanding plug is pushed forward and expanded in the forward direction. By expanding in opposite directions a cross expanding and squeezing effect is achieved to provide a very stable securing effect. A two-way sleeve and connecting sleeves may be further connected to provide fixed points for the expansion of the plugs and to extend the length of the expansion screw to meet different requirements.
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