Method of manufacture and machine for manufacturing subterranean wall drain

An apparatus for manufacturing subterranean drainage material comprising:

• means for continuously delivering plastic sheet material to a heating means;
• means for sensing the thickness of said plastic sheet material being delivered to said heating means;
• means for increasing or decreasing the temperature in said heating means in accordance with said sensed thickness;
• heating means for heating said plastic sheet material delivered from said delivery means;
• means for forming a plurality of hills and valleys in said heated plastic sheet material to define a plastic core having opposed upper and lower surfaces;
• means for cooling said formed plastic core;
• means for applying adhesive to said opposed upper and lower surfaces of said plastic core wherein said upper and lower surfaces are at least partially covered with adhesive, said adhesive applying means precluding adhesive from filling in said valleys, said adhesive applying means being positioned on opposed surfaces of said core;
• means for continuously feeding permeable fabric cloth to said adhesive covered opposed upper and lower surfaces of said plastic core, the fabric cloth having opposed longitudinal edges;
• and
• means for sealing said opposed longitudinal edges of said fabric cloth to enclose said plastic core and define a sealed fabric/core assembly.