Flexible screw

Flexible Screw-machinc Springs Springs Heavy... 

Customized and flexible screw-element and barrel segment designs, and fast and efficient melting and mixing (both dispersive and distributive) in most TSEs make such equipment very well suited and almost exclusively used for the following polymer processing operations ... 

Figure 3.10. Schematic diagram of flexible screw conveyor, spiral design, and examples of application. Courtesy of Spiroflow-Orthos Systems, Inc., Monroe, NC, USA.

Figure 3.10. Schematic of flexible screw conveyor, spiral design, and examples of application.

The flexible screw conveyor is another system with many advantages. Figure 3.10 shows the schematic diagram of a conveyor and examples of its applications. The only moving part of this conveyor is a flexible spiral directly driven by an electric motor and rotating within an outer tube. The system is totally sealed which makes it dust-free and eliminates atmospheric contamination (e.g., humidity). The spiral s gentle action does not degrade the material. This conveyor can convey in any direction and with a variable speed... 

Another crude form of screw elevator is the so-called flexible screw elevators. The very limited flexibility these machines possess is permitted by the use of a plastic tubular casing and continuous screw flight that does not have a centre shaft. These units mainly have small diameter coreless screws, i.e. without centre shafts, running at relatively high speeds. 

En masse conveyors were originally designed to convey materials in the horizontal plane only, but the conveying mode has proven to be effective in vertical conveying also, provided the inlet is kept fed with powder and the trough is enclosed (similar to the action in a flexible screw conveyor, see Chapter 7). 

Figure 7.19 Typical flexible screw conveyor (Spiroflow Ltd).

This section is devoted entirely to the specification and use of flexible screw conveyors (see Figure 7.19). More information on the design of screw conveyors can be found in Chapter 5. The key advantage of a flexible screw conveyor is that within the flexibility... 

Bourton, K. Clague, K. (2000) Understanding flexible screw conveyors. In From Powder to Bulk Interrmtional Conference on Powder and Bulk Solids Handling, IMechE Conference Transactions. London, UK, pp. 419-431. 

Flexicon Corporation (2006) Bag Dump Stations, Bulk Bag Dischargers, Bulk Bag Fillers, Drum Dumpers, Flexible Screw Conveyors, http //www.flexicon.com/us/index.asp. Accessed 21 November 2006. 

Unitrak Corporation Ltd (2006) Aeromechanical Conveyors, Bulk Bag Dischargers, Flexible Screw Conveyors. 

Forced elevation (including horizontal paths) mechanism is often associated with pneumatic-type conveying systems and some high-speed specialty mechanical conveyor systems such as flexible screw conveyors. 

Advantages Low screw speed suitable for very shear-sensitive products Positive pump - develops high pressures. Higher power - higher throughput potential Flexible screw design Excellent dispersive and distributive mixing. 

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