Arched tunnel excavator with tool bit replacing function

The invention discloses an arched tunnel excavator with a tool bit replacing function. The arched tunnel excavator comprises a main frame, a muck box is mounted on the left side of the lower portion in the main frame, and a spiral blade is mounted in a conveying channel. A first gear is mounted above a first rotary shaft, and a third gear is mounted on the right side of a second gear. A muck outlet is formed in the is formed in the upper portion of the right side of the conveying channel, and a muck inlet is formed in the upper portion of the muck box. A connecting plate is mounted above crushing rotary blades. Compared with a common arched tunnel excavator, the arched tunnel excavator with the tool bit replacing function has the advantages that by means of the arranged spiral blade, a first servo motor drives the second gear to rotate through the third gear, the second gear drives the first rotary shaft to rotate through the first gear, the first gear drives the spiral blade to rotate, and the spiral blade i