Torpedo for extruder

A torpedo for an extruder, the torpedo comprising:

• a longitudinal member which is provided at a periphery thereof with a plurality of thread portions which protrude outward and which are spaced apart in a circumferential direction;
• a plurality of sluice blades which are mounted so as to be movable on the longitudinal member and which are partially engaged in apertures of the longitudinal member, the longitudinal member and the sluice blades being provided with complementary radial guiding surfaces which are in contact with each other;
• and
• adjustment means for radially displacing the sluice blades relative to the longitudinal member,
• wherein the adjustment means comprise a longitudinal shaft which is rotatably mounted in a longitudinal channel of the longitudinal member, the longitudinal shaft and the sluice blades having complementary surfaces which cooperate in order to radially displace the sluice blades when the longitudinal shaft is displaced,
• wherein the longitudinal shaft comprises at least one radial plate, one radial face of which is provided with at least one helical groove, the sluice blades comprising a finger which is engaged in the at least one helical groove,
• wherein the sluice blades extend through spaces between the thread portions, respectively, and
• wherein the thread portions and the sluice blades are provided with complementary radial guiding surfaces which are in contact with each other.