Method of and a device for making drain pipes

Claim 1

A METHOD OF PRODUCING AND LAYING A DRAIN PIPE, IN WHICH A MOLE PLOW HAVING A HOLE FORMING PLUG DISPOSED BELOW A CUTTING KNIFE IS FORCED THROUGH THE GROUND FOR FORMING A SUBSTANTIALLY CYLINDRICAL BORE FOR RECEIVING THE DRAIN PIPE, SAID DRAIN PIPE BEING FORMED BY A FLEXIBLE FLAT STRIP WHICH IS UNWOUND FROM A SUPPLY DRUM CARRIED ON THE PLOW ABOVE THE LEVEL OF THE GROUND TO BE DRAINED TOGETHER WITH THE DEVICE BY WHICH THE MOLE IS PRODUCED, SAID METHOD COMPRISING THE STEP OF BENDING SAID STRIP MATERIAL INTO A VERTICAL TUBULAR FORM ABOVE THE LEVEL OF THE GROUND WITH THE OUTER EDGE EXTENDING FORWARDLY OF THE PLOW AND THE INNER EDGE EXTENDING REARWARDLY, BENDING THE FLEXIBLE STRIP, WHEN FORMING THE PIPE, INTO A CROSS SECTION SMALLER THAN THAT OF THE MOLE HOLE, BY OVERLAPPING THE EDGES OF THE FLEXIBLE STRIP AND LEAVING THEM IN AN UNSECURED CONDITION AND MAKING THE SAID OVERLAPPING SUFFICIENTLY GREAT THAT IT WILL BE MAINTAINED EVEN AFTER THE STRIP MATERIAL HAS BEEN ALLOWED TO EXPAND AFTER THE PIPE HAS BEEN DEPOSITED WITHIN THE MOLE HOLE, LAYING THE THUS FORMED TUBE BY CURVING IT DOWNWARDLY AND REARWARDLY OF THE PLOW INTO THE MOLE HOLE THROUGH THE SPACE CUT BY THE KNIFE CARRYING THE MOLE PLOW WITHOUT ANY LONGITUDINAL MOVEMENT BETWEEN THE DRAIN PIPE AND THE MOLE HOLE, AND POSITIONING SAID UNSECURED OVERLAPPING EDGES OF THE STRIP WITH THE OUTER EDGE EXTENDING DOWNWARDLY AND THE INNER EDGE EXTENDING UPWARDLY TO FORM A DOWNWARDLY OPENING VERTICAL SLIT ALONG ONE SIDE OF THE DRAIN PIPE.

Claim 2

A METHOD OF PRODUCING AND LAYING A DRAIN PIPE, IN WHICH A MOLE PLOW HAVING A HOLE FORMING PLUG DISPOSED BELOW A CUTTING KNIFE IS FORCED THROUGH THE GROUND FOR FORMING A SUBSTANTIALLY CYLINDRICAL BORE FOR RECEIVING THE DRAIN PIPE, SAID DRAIN PIPE BEING FORMED BY A FLEXIBLE FLAT STRIP WHICH IS UNWOUND FROM A SUPPLY DRUM CARRIED ON THE PLOW ABOVE THE LEVEL OF THE GROUND TO BE DRAINED TOGETHER WITH THE DEVICE BY WHICH THE MOLE IS PRODUCED, SAID METHOD COMPRISING THE STEP OF BENDING SAID STRIP MATERIAL INTO A VERTICAL TUBULAR FORM ABOVE THE LEVEL OF THE GROUND WITH THE OUTER EDGE EXTENDING FORWARDLY OF THE PLOW AND THE INNER EDGE EXTENDING REARWARDLY, BENDING THE FLEXIBLE STRIP, WHEN FORMING THE PIPE, INTO A CROSS SECTION SMALLER THAN THAT OF THE MOLE HOLE, BY OVERLAPPING THE EDGES OF THE FLEXIBLE STRIP AND LEAVING THEM IN AN UNSECURED CONDITION AND MAKING THE SAID OVERLAPPING SUFFICIENTLY GREAT THAT IT WILL BE MAINTAINED EVEN AFTER THE STRIP MATERIAL HAS BEEN ALLOWED TO EXPAND AFTER THE PIPE HAS BEEN DEPOSITED WITHIN THE MOLE HOLE, LAYING THE THUS FORMED TUBE BY CURVING IT DOWNWARDLY AND REARWARDLY OF THE PLOW INTO THE MOLE HOLE THROUGH THE SPACE CUT BY THE KNIFE CARRYING THE MOLE PLOW WITHOUT ANY LONGITUDINAL MOVEMENT BETWEEN THE DRAIN PIPE AND THE MOLE HOLE, AND POSITIONING SAID UNSECURED OVERLAPPING EDGES OF THE STRIP WITH THE OUTER EDGE EXTENDING DOWNWARDLY AND THE INNER EDGE EXTENDING UPWARDLY TO FORM A DOWNWARDLY OPENING VERTICAL SLIT ALONG ONE SIDE OF THE DRAIN PIPE.