Split type diamond pre-milling cutter

The split type diamond pre-milling cutter comprises a cylindrical body (1), a plurality of cutting units (2) are arranged on the cylindrical surface of the cylindrical body (1), an included angle is formed between a chip pocket (3) and the axis of the cylindrical body (1), an installation groove (4) and the chip pocket (3) are arranged in a staggered mode and communicated with the chip pocket (3), and the depth of the installation groove (4) is larger than that of the chip pocket (3). A threaded hole (5) is formed in the groove bottom of the mounting groove (4), an L-shaped support (6) matched with the mounting groove (4) is placed in the mounting groove (4), the vertical portion of the L-shaped support (6) extends out of the mounting groove (4), a spigot (7) is formed in the side face of the extending end of the L-shaped support (6), and a diamond blade (8) is welded in the spigot (7). The utility model has the beneficial effects that the material waste is avoided, the use cost is saved, and the damaged diam