Method for manufacturing a drip irrigation tube and dripper unit therein

A manufacturing method for a drip irrigation tube, comprising:

• manufacturing dripper units,
• attaching said dripper units longitudinally to a thread by positioning them at intervals along the latter,
• introducing said thread inside said tube while the latter is being formed in an extruder or extrusion station so as to draw the dripper units therein one after the other,
• heat welding said dripper units to the inner wall of the tube during its formation, the resulting attachment allowing the thread and the dripper units to be moved forward at the same time as the tube, and
• cooling said tube and perforating the latter at right angles to each dripper unit in order to make it communicate with the exterior,
• said method further comprising:
• providing said dripper units with clamping means during manufacturing thereof, and
• inserting said thread into said clamping means in order to obtain attachment of said dripper units to said thread before introduction thereof into said tube;
• and
• forming a waiting line formed of a predetermined number of dripper units, after attachment thereof to said thread and prior to introduction thereof into said tube;
• said method further comprising:
• drawing said dripper units in succession into a first caterpillar including an upper belt and two lower belts driven by conjugated movements, said lower belts being placed side by said below the upper belt and said dripper units being inserted in the gap between said belts;
• unreeling said thread from a spool by passing it over a portion of the periphery of an insertion wheel whose peripheral rim is concave over the edge and which projects into said gap between the two lower belts and which is driven by a rotational movement coordinated with the movement of said belts;
• said dripper units proceeding in said gap and being positioned so that said notch overlaps said peripheral edge so that said thread is caught in the notch of each dripper unit when the latter passes above said wheel;
• monitoring the number of dripper units placed in said waiting line;
• and
• varying the speed of progression of the dripper units in said first caterpillar and that of said thread on said wheel as a function of said number.

A method for manufacturing a drip irrigation tube comprising:

• manufacturing dripper units,
• attaching said dripper units longitudinally to a thread by positioning them at intervals along the latter,
• introducing said thread inside said tube while the latter is being formed in an extruder so as to draw the dripper units therein one after the other,
• heat welding said dripper units to the inner wall of the tube during its formation, the resulting attachment allowing the thread and the dripper units to be moved forward at the same time as the tube, and
• cooling said tube and perforating the latter at right angles to each dripper unit in order to allow it communicate with the exterior, said method further comprising:
• causing said dripper units to progress into said extruder on a caterpillar which passes longitudinally through the latter and extends substantially between the inlet of said extruder and a point where said dripper units adhere to the inner wall of said tube;
• and
• moving said caterpillar along at a speed substantially equal to the extrusion speed of said tube.