Synthetic resin pipe manufacturing apparatus

A synthetic resin pipe manufacturing apparatus comprising:

• an extruder (20) configured to, while slowly rotating a resin supplied from a raw material supply device (10), extrude a synthetic resin pipe (50) through a blow molding portion (21) such that a hollow portion (51) is formed in a spiral shape in a longitudinal direction;
• an air supply pipe (40) provided inside the extruder (20);
• an air fitting (41) having a cylindrical shape with the same inner diameter as the synthetic resin pipe (50), the air fitting (41) being disposed in front of the air supply pipe (40) to support an inner surface (52) of the synthetic resin pipe (50) as the synthetic resin pipe (50) is extruded from the extruder (20) and introduced into a cooler (30a) of a dice (30);
• an air ejection pipe (42) disposed in front of the air fitting (41) and having a plurality of air holes (42′) formed therein to cool the inner surface of the synthetic resin pipe (50);
• an air discharge plate (43) disposed in front of the air ejection pipe (42) and having a plurality of air discharge holes (43′) perforated through the air discharge plate (43) to discharge to the outside hot air generated by cooling the inner surface of the synthetic resin pipe (50) with air ejected through the air holes (42′),
• wherein the air supply pipe (40) is disposed behind the air fitting (41) and has a plurality of air holes (44) formed therein to discharge air and cool the hollow portion (51) of the synthetic resin pipe (50) while the synthetic resin pipe (50) is being extruded from the extruder (20);
• and
• a rotation driver (90) configured to transmit rotation power to the air supply pipe (40),
• wherein the rotation driver (90) rotates the air supply pipe (40) and thereby rotates the air fitting (41), the air ejection pipe (42), and the air discharge plate (43) that are integrally formed with the air supply pipe (40),
• wherein a plurality of recesses (431) recessed at equal intervals along a circumference of an outer circumferential surface of the air discharge plate (43), each recess (431) having a semicircular groove structure and allowing hot air to pass between the recess (431) and the inner surface 52) of the synthetic resin pipe (50) so that the hot air is discharged to the outside in conjunction with the air discharge holes (43′),
• wherein the synthetic resin pipe manufacturing apparatus further comprises an ultrasonic inspection unit (400A) and a cooling zone (30c), the ultrasonic inspection unit (400A) being configured to perform a surface inspection of the synthetic resin pipe (50) as the synthetic resin pipe (50) passes through the air discharge plate (43), and the cooling zone (30c) having a larger diameter than the synthetic resin pipe (50) and being formed behind the air discharge plate (43) in the cooler (30a) of the dice (30).