insert bolt

基本解释

A hexagonal molded rubber head forms around the rounded head of the metal bolt insert.
螺栓頭部採用六邊形形狀，內部附有金屬。
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First, assembly with temporary bolts. Amount of temporary bolts should be no less than the 1/3 of total connecting bolts. Align steel bar with hole, and insert temporary bolt and screw down nut.
首先用臨時螺栓拼裝，個數不應少於接頭螺栓縂數的1/3以上，方法是先用鋼穿杆對準孔位，在適儅位置插入臨時螺栓擰緊螺母；
Slam latch is screwed onto latch support which is either screwed or welded to the door. Assembled without insert it can be opened with a tapered square key. Bolt has free stroke.
這種鎖舌用螺絲裝在鎖支架上，而鎖支架用螺絲固定或銲接在門上，無鎖芯的裝配時，可用錐形四方匙開啓鎖栓爲自由行程。

But invariably there is play between the threads of the bolt and the female insert because the teeth don't fit perfectly.
FORBES: Magazine Article