Isothermal Blade Deflection

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3. Experimental Study 3.1. Experimental setup In order to carry out the isothermal blade forging process to study the dimensional and geometrical errors during the forging process, there is a need to precisely control the deformation rate and the temperature during the forging process; so, a 6 MN hydraulic press was equipped with a servo-hydraulic power-pack and a PLC control system. An electrical furnace, isolated form the press bed by cooling water plates, was used to heat the dies. The dies were fabricated from a nickel-base superalloy to withstand the isothermal-forging stresses. Both of the preform and dies were held enough in the furnace to remove the temperature gradient inside them. 3.2. Experimental tests To conduct the isothermal…show more content…
5. The maximum elastic die deflection is 0.131 mm at the middle of the airfoil near the platform. Several parameters affect the elastic die deflection, including the friction factor at the workpiece-die interface, the flow stress of Ti-6Al-4V and the elastic modulus of the dies. Increasing the temperature results in lower flow stress and elastic modulus, and higher friction factor. The former results in lower deformation force and consequently lower die deflection. In considering the elastic die deflection, the flow stress has opposite effect to the elastic modulus and the friction factor. Increasing the deformation rate increases the flow stress, but at the same time decreases the friction factor that have opposite effects on the elastic die deflection and consequently the thickness…show more content…
The leading and trailing edges undergo more deformation and more adiabatic temperature rise (Fig. 7). Increasing the deformation rate results in a higher adiabatic temperature rise. Moreover, lower initial temperature leads to more flow stress and more adiabatic temperature rise. The temperature distribution coupled with the varying thickness of the airfoil profile results in the non-uniform cooling of the blade and consequently deviation of the airfoil. Because of small thickness in leading and trailing edges, they cool faster than the central portion of the airfoil that increases their strength. The contraction of the central area results in the warpage of the airfoil and twist and/or bow

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