Screw-type extruder having a starting valve and throttle

A screw-type extruder comprising:

• a housing (1) which is provided with at least one bore (5,6) having a first end and a second end, with a hopper (15) for receiving material and opening into said at least one bore at said first end and with a delivery channel (23) at said second end;
• at least one screw (9, 10) which is rotatably arranged in said at least one bore (5, 6) of the housing (1) and which conveys said material while melting or plasticising into a conveying direction (18) from said hopper (15) to said delivery channel (23);
• a starting valve for channeling said material out of said housing during a starting operation of the extruder and a throttle valve for generating a back pressure on the molten or plasticized material, the starting valve and the throttle valve comprising:
• a valve-throttle housing (21) having a guiding and starting bore (27), said guiding and starting bore has a starting outlet opening and passes through said delivery channel (23) and said delivery channel (23) leads into said guiding and starting bore (27) with an inlet opening and leads out of said guiding and starting bore (27) with an outlet opening and passes in a straight line through said guiding and starting bore (27);
• a starting valve and throttle body (28) which has a longitudinal axis (29) and which is arranged in said guiding and starting bore (27) so as to be displaceable at right angles to the conveying direction (18) in the direction of the longitudinal axis (29) between a first end position and a second end position of displacement, the first end position being a starting position and the second end position being a throttling position;
• and
• wherein the starting valve and throttle body (28) has two closing bodies (31, 32) and a throttle body (33), which is arranged between said two closing bodies (31, 32) and a starting valve body (34), which is arranged on one of said two closing bodies (32) remote from the throttle body (33), and
• wherein in said first end position of said starting valve and throttle body (28) said starting valve body (34) connects said inlet opening of the delivery channel (23) to the said starting outlet opening (35) whereby said outlet opening of said delivery channel (23) is closed, and
• wherein in said second end position of said starting valve and throttle body (28) said throttle body (33) connects said inlet opening to said outlet opening of said delivery channel (23), whereby said one closing body (32) on which the starting valve body (34) is arranged closes said starting outlet opening (35), and
• wherein the throttle body (33) is in the form of a vane-type throttle having at least one throttling surface (52, 53) which, together with at least one associated throttling channel bounding surface (54, 55) defines at least one throttling channel (56, 57) the length (1) of which is variable by pivoting the throttle body (33) about said longitudinal axis (29) to vary said back pressure on the molten or plasticized material.