| 摘要 |
A method of manufacturing a rotary drill bit of the kind comprising a bit body having a shank for connection to a drill string, a plurality of cutting structures mounted in sockets in the bit body, and a number of nozzles also mounted in sockets in the bit body and communicating with a passage for supplying drilling fluid to the face of the bit. The method includes the steps of forming at least part of the bit body from steel, forming the sockets in the bit body part, plugging each socket with a former which projects partly beyond the bit face, applying to the bit face a coating of a fusible hardfacing material, heating the coated bit body part so as to fuse the hardfacing material, cooling the bit body part to solidify the fused hardfacing material, and then removing the formers from the sockets. Each former is formed of material, such as austenitic stainless steel, having a higher coefficient of thermal expansion than the steel of the bit body part, and is so dimensioned that it can be readily inserted into its socket at ambient temperature but expands relatively to the socket at the fusing temperature so as tightly to engage the interior surface of the socket. |
