Pipe supporting device and PVC pipe shearing device

The utility model provides a pipe supporting device and a PVC pipe shearing device. The pipe supporting device comprises a driving gear and a pipe supporting mechanism. The pipe supporting mechanisms are arranged at the two ends of the driving gear respectively, and each pipe supporting mechanism comprises a gear transmission structure and a plurality of supporting pieces connected with the gear transmission structure. The gear transmission structure is configured to rotate under driving of the driving gear and drive the supporting piece to move in the direction away from or close to the driving gear so as to adjust the diameter of the pipe supporting mechanism. When the PVC pipe is sheared, the pipe supporting device is additionally arranged, so that the pipe can be prevented from deforming during shearing, and normal use of the pipe is guaranteed. On the other hand, the diameter of the pipe supporting mechanism can be adjusted, and therefore the pipe shearing device can be used for shearing pipe fittings wi