The invention provides a pneumatic rear clamping disc for a
pipe cutting machine. The pneumatic rear clamping disc comprises a fixing base, a
piston, an air cylinder, a fixing frame, a pushing block,a first clamping claw unit and a second clamping claw unit. The fixing frame is arranged on the top of the fixing base. An end plate is arranged on the top of the fixing frame. The
piston is arrangedin the fixing base. The air cylinder is fixed in the
piston. A pushing rod of the air cylinder penetrates through the fixing frame. The pushing block is arranged at the
tail end of the pushing rod. The first clamping claw unit and the second clamping claw unit are symmetrically arranged on the end plate. The first clamping claw unit is connected with the piston. The second clamping claw unit is connected with the pushing block. According to the pneumatic rear clamping disc, the same air cylinder is adopted for driving the first clamping claw unit and the second clamping claw unit at the same time, the rear clamping disc is flexible in motion and easy to operate, meanwhile, by means of the simple mechanical structure and independent gas
circuit design, the rear clamping disc is more compactin construction, clamping is more reliable, and the defects that due to the complex and large structure of the rear clamping disc, operation is troublesome, centering performance is poor, the rear clamping disc cannot penetrate through a cavity of a front clamping disc, and
tail materials cannot be saved can be avoided.