Bolt wraps up a cylinder, which has a seamless. Knock out a hole on the wall when using, then put the expansion bolt into the hole. When the bolts were tightened, the cylinder was squeezed and open. This makes the bolt stuck in the hole to play a fixed role. 1. Second casting method can be used, that is, in casting aside base, reserving the appropriate size of holes for bolts(the size of holes for reserving can be properly adjusted according to the size, the buried depth of the bolts ). When the devices arrive and determine the location of bolt holes of equipment base, then put screw into the bolt hole for the second casting fixed. 2. If the casting for basis had been finished, and the bolt position is not offset badly, you can change the original bolt hole to a long-circle hole according to the actual situation in the base of the device, and add to the smooth steel plate on the basis to make of slide bearings in order to keep the equipment be in place. If the device does not allow to move, you can weld the base with steel plate. Seam height can be designed under the size of the base and plate. Source: Goodbolts. Com
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http://www.goodbolts.com/read.asp?id=983