Extruder gear box

The massive gear boxes of the extruder drive has the following design criterions ... 

The new commercial process was based on the lab process and has the target performance shown in Table 9.2. To achieve this performance, an 80 mm diameter extruder with an L/D ratio of 28 was specified. The extruder was built with a 100 kW motor and a gear box such that the maximum speed of the screw was 117 rpm. A gear pump was positioned downstream of the extruder such that the extruder only needed to generate 6 MPa of pressure at all rates. 

Fig. 2. Internieshing co-rotating twin-sciew extruder A, motor B, gear box C, feed port D, clam shell barrel E, vent port F, screw shafts G, conveying screws H, kneading paddles I, barrel valve and J, bHster rings. Courtesy of APV Chemical Machinery Inc.

There are extruders that are utilized for just one process or a specific task. In this case, it suffices to define exactly one speed for their drive. A fixed-speed motor is used and operated directly from the mains. In such cases, a manual switching stage is provided on the gear box so that it can run at a second constant speed. The screw speed typically ranges between 200 and 300 rpm. 

Has restrictor bar or flow dividers in each polymer channel but with blown film dies, control is by individual extruder speed or gear boxes. 

Recent changes in gear-box design have produced dramatic increases in the output of corotating twin-screw extruders. In these extruders, the high power-factor gear boxes permit a 40 percent increase in torque and screw speeds up to 1200 r/min. As a result, smaller-diameter extruders provide the output that once required much larger machines. 

The main components of an extruder are mixing and plasticizing devices (screw), barrel, gear box and drive train, instrumentation, and heat-... 

The extruder drive train (motor and gear box) must be able to provide initial start-up torque and maintain the horsepower required to deliver the required output. The dc drives are preferred because of their accurate speed control and efficiency. They also provide constant torque over a wide range of operating speeds. 

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