A machining tool forms a first relief surface, a valve seat surface, and a second relief surface by cutting the inner periphery of a valve seat blank having an opening. The machining tool is provided with: a tool body rotationally driven about an axis; a plurality of cutting tools rotating with the tool body; a cartridge mounted to the tool body so as to be capable of moving forward and backward along the axis; and a cam in contact with the base end surface of the cartridge and moving the cartridge forward and backward. At least one of the plurality of cutting tools is mounted to the cartridge.

A machining tool forms a first relief surface, a valve seat surface, and a second relief surface by cutting the inner periphery of a valve seat blank having an opening. The machining tool is provided with: a tool body rotationally driven about an axis; a plurality of cutting tools rotating with the tool body; a cartridge mounted to the tool body so as to be capable of moving forward and backward along the axis; and a cam in contact with the base end surface of the cartridge and moving the cartridge forward and backward. At least one of the plurality of cutting tools is mounted to the cartridge.

The present invention discloses a liquid injection type reamer bit, which comprises a drilling and reaming rod (1), a drilling tool (2) and reaming tools (3). The reamer bit is adopted to perform drilling and reaming operations respectively in a water pressure adjusting manner, has the advantages of simple structure, convenient operation, small volume, light weight, flexible and reliable technology, unified power sources for drilling and reaming, stable reaming, easy recovery of tools, and realization of reaming while drilling, greatly improves the anchoring reliability of anchor bolts, and ensures the safety of workers during underground work.

The present invention discloses a liquid injection type reamer bit, which comprises a drilling and reaming rod (1), a drilling tool (2) and reaming tools (3). The reamer bit is adopted to perform drilling and reaming operations respectively in a water pressure adjusting manner, has the advantages of simple structure, convenient operation, small volume, light weight, flexible and reliable technology, unified power sources for drilling and reaming, stable reaming, easy recovery of tools, and realization of reaming while drilling, greatly improves the anchoring reliability of anchor bolts, and ensures the safety of workers during underground work.