Inflatable rubber mandrel is a kind of expandable, shrinkable cylindrical bag, used to form the cavity of the concrete member, when the hollow member is made, it is put into the middle, and filled with compressed air, when the concrete solidifies, the compressed air in the bag is released, the capsule is contracted, and the capsule can be extracted from the cavity. It is easy to use, economic and durable, uninflated can be soft contraction, arbitrary folding, curling, inflation after expansion has enough strength to withstand the pressure of concrete, which is unmatched by any traditional rigid formwork.

It is suitable for pumping holes in reinforced concrete components, including pile, roof truss, roof slab column, beam, underpass and other components, and is widely used in: industrial and mining foundation, highway bridge, construction engineering, water conservancy engineering (dock, berth, wharf). The construction practice has proved that the capsule extraction process equipment is simple, not only saves materials, but also has the characteristics of changeable shape, and can be formed into round, oval, rectangular, arch, octagon, trapezoid and other pipes. It can also be formed into straight holes, changing the face, etc., which can make the building structure become light, thin wall hollow, and change the situation that the concrete has been using rigid formwork.