Method for producing an extrusion molded product

A method for producing an extrusion molded product, wherein comprising:

• holding a core material of synthetic resin extruded from an extrusion machine with a holder for supporting and feeding the core material, the holder being provided with cutting guide holes formed on the right and left hand sides of the holder such that cutting blades are allowed to go through the cutting guide holes and form grooves on the right and left hand sides of the core material, the cutting guide hole formed on the right hand side of the holder and the cutting guide hole formed on the left hand side of the holder being shifted from each other with a gap in the direction in which the core material is sent out;
• starting rotation of the rotary bodies provided with the cutting blades while the core material and the holder for feeding the core material stand by at a predetermined standby position that does not enable the cutting blades to cut the core material;
• after the rotation speeds of the rotary bodies reach predetermined rotation speeds optimal for the cutting blades to cut the core material, moving the holder or the rotary bodies so that the cutting blades can start cutting the core material that is proceeding through the holder, and
• then allowing the cutting blades, attached on the left and right rotary bodies, to go through the left and right respective cutting guide holes of the holder, thereby cutting both of the left and right hand sides of the core material such that the grooves formed on the right hand side of the core material and the grooves formed on the left hand side of the core material are shifted from each other with a gap in the direction in which the core material is sent out, thereby forming a plurality of grooves in series at arbitrarily spaced intervals on the right and left hand sides of the core material.