On-line monitoring device for detecting outer diameter of internal thread finished product

The utility model discloses an on-line monitoring device applied to external diameter detection of an internal thread finished product. Monitoring platform, a monitoring box and a pipe reversing assembly are arranged on one side of the upper surface of the monitoring platform. The monitoring box is slidably connected with the monitoring platform. A first screw rod and a second screw rod are rotationally mounted in the monitoring box; the first lead screw and the second lead screw are fixedly connected through a coupler. The ends, away from the coupler, of the first lead screw and the second lead screw are in transmission connection with first motors correspondingly. Two groups of monitoring plates are slidably mounted on the surfaces of the first screw rod and the second screw rod; touch switches are symmetrically mounted on one sides of the two groups of monitoring plates; and the touch switch is electrically connected with the first motor, the pipe reversing assembly comprises a rotary disc, two sets of fir