Flange threaded hole machining tool for investment casting

The utility model discloses a flange threaded hole machining tool for investment casting. The positioning device comprises a back disc fixedly connected to a lathe and a positioning assembly installedon the back disc. Structurally, the device is fixedly connected to a lathe through a back disc. A supporting platform is machined on the back disc; a workpiece is fixedly installed on the supportingplatform to be machined. Integral structure is simple, the coaxiality with the main shaft of the lathe is ensured through the fixed connection mode of the circular back disc; therefore, the coaxialityof the threaded hole to be machined in the workpiece and the lathe spindle is ensured; the machining precision of the threaded hole is improved; and the machining efficiency of the workpiece is alsoimproved through machining of the lathe, the labor intensity of workers is reduced, lightening holes are machined in the back disc and the supporting platform, installation is more convenient and faster, scrap iron generated by