Spinning head

The results obtained must be interpreted from the point of view of the modern theory of spin detonation [4, 5]. In the works cited only the region in which ignition of the gas occurs (the so-called head of the spin or shock wave kink ) was considered. The conditions were found—the speed of the oblique shock wave and corresponding pressure p2 and temperature T2—at the spin head, i.e., the conditions under which ignition occurs in spin detonation. The size of the head b2 and the reaction time r2 at the spin head under these conditions were considered quite small the question of conditions for the existence/feasibility of spin detonation was not posed. 

Further theoretical investigation of the problem led to the following conclusions for ignition to occur at the spin head it is necessary that the ratio r2/b2 be smaller than a certain quantity. By studying conditions at the... 

Since a rapid flow of gas occurs from the ignition zone at the spin head, rather than slow heat transfer, the critical value of r2/i>2 at the head is smaller than the critical value of Ti/d. for a normal wave in a tube. 

Figure 1 Spinning plant for high-tenadty polypropylene yams 1, spinning head 2, heating zone 3, water cooling bath 4, 5, drawing 6, relaxing zone 7, take up.

Figure 3 Spunbond line 1, extruder 2, spinning head 3, cooling air 4, web-formation chamber 5, suction blower 6, conveyor screen 7, nonwoven material 8, calander, winder.

Atomiser. A device to produce a fine spray of small particles or liquid droplets. In a spray dryer, the atomiser may be a nozzle, or a spinning head which produces the spray centrifugally. 

Figure 3.14 A 400-jet modular spin head available for scaling up electrospinning. Line speeds of 20-1000 fpm are claimed. (Courtesy of Nanostatics Inc., Columbus, OH.)...

Currently, there are two standard electrospinning setups, one with vertical spinning head and the other with horizontal spinning head. With the expansion of this technology, several research groups have developed more sophisticated systems that can fabricate more complex nanofibrous structures in a more controlled and efficient maimer [62, 63]. 

Figure 12.5 SEM images at different magnification (lOOx and 500x) of cellulose fibrous mats obtained by electrospinning from molten cellulose/NMMO solutions electrospun with different spinning parameters (cellulose content in the spinning solution 6 wt%, working distance 5 cm, applied voltage 11 kV, temperature of spinning head 100°C). Temperature of the needle (a) and (b) 96 C, (c) and (d) 130 C. (Adapted from Reference [81]).

All the known methods for spunbond fabrication with spin extruders process the chips into a melt, which is then guided by means of spinning heads with internal melt piping systems and spinning pumps and extruded through the spinnerets (with different round, rectangular cross sections) to the filaments. Following the filament path, the main takeup ways to obtain the filament bundle are [163, 164] ... 

Hot compressed air leaves the spinning head close to the melt drops and elongates them to long filaments up to breaking (e.g., the Exxon Melt Blow Process see the next section). 

The last device in the extrusion process is the spin head. The spin head consists of a pump block, heating device, and spin packs. The metered polymer from the extruder flows to the metering pump and into the spin pack. A heated housing surrounds the pump block, metering pump, and spin pack to maintain all the equipment that comes into contact with the polymer at the desired temperature required for proper extrusion of the polymer. 

The key to the melt blowing process is the spin head. The basic principle is the extrusion of low viscosity polymer melt through a single row of very fine holes placed close together in the order of 1000-4000 holes per m. lliese... 

---