Injection screw

Affected by corrosion and erosion of the rotor and casing, increasing the gas-slip internal recycle. This problem is not serious for water- or oil-injected screws. 

Figure 3,5 Nomenclature of an injection screw (top) and extrusion screw (courtesy of Spirex Corp.)...

Compressors (low pressure, water injected, screw type) 340/hp 30... 

The pipeline transport of H2 requires compression. The electrolysis plant uses low pressure, water injected, screw type compressors to compress H2 from 1.02 bar to 8.0 bar to transport the H2 a short distance ( 10 miles) to a pipeline compression station. The energy to compress H2 from 1.02 bar to 8.0 bar is 1.37 kWh/kg of H2. There is no need for H2 storage at the electrolysis plant. At the pipeline compression station, the H2 is compressed from 8.0 bar to a pipeline pressure of 69.0 bar by high-pressure reciprocating compressors. The energy to compress H2 from 8.0 bar to a pipeline pressure of 69.0 bar is 1.17 kWh/kg of H2. PV electricity is used to power the compressors and water pumps at the compression station. 

A series of composites of polystyrene (PS) and block poly(styrene-butadiene) (SBS) prepared by extrusion blending in the injection screw and injection moulding were studied by Fourier transform infrared (FTIR) analysis. Moulded samples were then dissolved and cast as a film and again studied using FTIR, with higher levels of miscibility noted than on the original moulding. SBS content of the samples was between 20 and 80 percent, with studies also completed on the pure polymers. Differences observed from simulated spectra of the polymer composites were explained by interactions between the two polymers due to partial miscibility. Corroboration of results was provided by calorimetry studies. 16 refs. 

Injection-molding pressure n. (1) The pressure applied to the plastic by the injection screw (or ram) during the injection stroke. (2) The pressure of the melt within the mold cavity just prior to the freezing of the gate. 

Push-pull molding n. An injection-molding technique that uses twin injection units to fill a mold through well separated gates. By oscillating the advance and retraction of the injection screws or rams, the material in the mold is sheared and oriented, breaking up weld fines. It is particularly suited to molding of liquid-crystalline polymers. 

Injection (screw moving forward without rotation)... 

Like an extruder, an injection moulding machine uses a screw to feed and plasticate the melt. There are however, a number of design differences between the two. An injection screw must withstand both higher pressures and intermittent stop-start use. It must be able to inject as well as move back to prepare the next weight of shot. 

Form die, injection screw, sleeve, plunger, cylinder, nozzle, gate, and so on Form die, plunger, blast nozzle, machine parts, and so on Form die, core rod, extrusion die, screw, and so on Cutting tool, cutting knife, drilL tap, gage pin, tool holder, guide plate, and so on... 

Screw notary compressor uses two helical screw rotors to compress gas. There arc two types of screw rotaiy compressor in the marlciet oil-free screw compressor (Figure 14d) and oil-injected screw compressor (Figure 14e) (abbreviated as OFS and OIS), They become popular recently and are used to replace centrifugal and nociprocating compressors in many sppiications. The efficiency of cither OFS orOIS compressor is about file same as a comparable centrifugal compres. ior at 70 -... 

The PFM-LSR metering and mixing system has been developed by 2KM to overcome some of the technical limitations which exist for the injection moulding of liquid silicone mbber. PFM-LSR technology is claimed to offer such advantages as exact metering directly onto the injection screw to eliminate pressure losses the variable shortest mixing distance which eliminates the need for a material pressure reduction valve variable material feed and a modular concept with simple expansion possibilities. These features are described. 

Figure 3.5 Sections of an injection screw, (a) passive screw, (b) standard screw...

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