PUCHING APPARATUS FOR LOW PRESSURE PIPE

A punching apparatus for a low pressure pipe is provided to cut off leakage of gas by opening/shutting a sandwich valve, and prevent damage of pipes and a perforating cutter by permitting the perforating cutter and rods to move in a vertical direction along a rack gear of a guide bar. A punching apparatus comprises a sandwich valve(105), a perforating coupling(109), a rod coupling(110), a gear box(111), and a perforating cutter elevation unit. The sandwich valve is coupled onto a tee flange so that an open/shut plate moves in forward and rearward directions by the rotation of an open/shut lever(103) coupled to one end of the sandwich valve, and opens/shuts an open/shut hole of the tee flange. The perforating coupling is coupled onto the sandwich valve, and has a space for accommodating a perforating cutter and a center drill. The perforating coupling has a top with a joint hole. The rod coupling permits a rod coupled to the perforating cutter through the joint hole of the perforating coupling to stand upright. The gear box has an output shaft(111a) arranged on the rod, and an input shaft(111b) where a driving motor(112) is coupled. The gear box decelerates rotary frequency of the driving motor transmitted to the input shaft by a predetermined deceleration ratio, and outputs the decelerated rotary frequency to the output shaft. The perforating cutter elevation unit moves the rod and the perforating cutter in a vertical direction.