Economical and laborsaving reinforcing bar coupler

Abstract

A coupling device is disclosed for rapidly and ecnomically mechanically joining a pair of elongated structural elements such as reinforcing bars in the field. The cylindrical couplingdevice includes an outer annular chamber containing porous substance which can be made to react exothermically, such as a mixture of aluminum and iron oxide powder which releases molten material, e.g. iron, upon being activated. The mass of exothermic material includes air in a quantity determined by the material's porosity when packed into the outer annular chamber. When the exothermic material is made to react, it heats the contained air and causes it to expand and act as a propellant, which causes molten iron from the exotheric reaction to be propelled from the outer chamber into an interior cylindrical chamber or chambers which contain the ends of the reinforcing bars. The flow speed and amount of propelled molten material deposited in the gap are regulated by: the dimensions of the passageways between inner and outer chambers, the radial clearance gap between the reinforcing bars and the inside surfaces of the inner chambers, and length of the inner chambers. When these parameters are properly adjusted, especially the size and number of passageways between outer and inner chambers, then molten material propelled into the radial clearance gap solidifies therein to produce solid masses of iron which funtcion as keying elements to join the reinforcing bars to the coupler.