Nozzle Design
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Nozzle Design John A. Webster Cool-Grind Technologies Connecticut USA, Storrs Mansfield, CT, USA
Definition of Nozzle A nozzle is a device designed to control the flow of a fluid as it exits a pipe. Nozzles are frequently used to control the rate of flow, velocity, direction, and profile of a liquid stream before it enters a manufacturing process. The word “spout” is sometimes used in the USA instead of “nozzle.”
Theory and Application Overview In wet grinding, the nozzle(s) is used to condition the flow of a cutting fluid from a pump into the grinding process with a certain direction, profile, flow rate, and pressure to make the grinding process successful. The direction can be either radial, axial, or tangential to the grinding wheel or a combination of two or more directions. The flow rate has to be sufficient to extract process heat and allow the lubricity additives to function. The profile of the jets should ideally match the profile of the grinding wheel active surface profile. Pressure
is used to accelerate the fluid to a certain velocity to impinge the wheel and thereby wet it or to force the fluid into the porosity of the grinding wheel. The applied flow rate is a function of the nozzle pressure (giving velocity) and the exit aperture of the nozzle. The four common types of nozzles used for grinding are flood (typically less than 1 bar pressure), jet (pressures up to 50 bar), spray (pressures up to 100 bar), and shoe (typically 1–15 bar pressure). The design of these four types of nozzles is very different, but they each have their merits (Webster et al. 1995; Brinksmeier et al. 1999, 2000; Ott 1991). Flood Nozzles
Flood nozzles (Fig. 1) can often be assembled from multiple modular spherical joints, and predominantly are made from plastic or metallic material. A majority of new grinding machines are supplied with these nozzles since they are inexpensive and allow users to exploit much of the capability of the machine for minimum cost. For optimized coolant application, they are often replaced by an engineered nozzle system. If the pressure supplying such flood nozzles is increased to more than 2–4 bar, then the plastic articulated nozzles can deflect due to the jet reaction force and thereby misalign the flow to the grinding process. Metallic modular nozzles can withstand much higher pressure but are considerably more bulky and difficult to aim. The flow inside modular nozzles can also be very turbulent at higher
# CIRP 2018 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, https://doi.org/10.1007/978-3-642-35950-7_6432-3
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Nozzle Design
Nozzle Design, Fig. 1 Modular plastic nozzles. (Courtesy Webster)
Nozzle Design, Fig. 2 Coherent-jet nozzles. (Courtesy Webster)
flow rates, due to the interrupted internal geometry between each segment, which leads to a dispersed jet even when an efficient nozzle is fitted. Jet Nozzles
Jet nozzles (Webster et al. 1995; Morgan et al. 2008; Spur and Brucher 1995) create a powerful stream of fluid with the aim of wetting the wh
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