Selecting width of cylindrical flap wheels for turret heads when grinding large size outer-forming parts

In order to obtain the desired shape of long size panels and skins for the aerospace industry, the technology of shot peen forming with subsequent grinding with a flap wheel is successfully applied. This includes sequentially-performed operations of shot peen forming, grinding and shot hardening. In the present study, a special UDF-4 (shot peen forming equipment of the 4th version of modernisation) installation, designed and manufactured for this purpose, is described. The latest version of this installation is equipped with a numerical program control system and a turret grinding head with 4 flap wheels for optimising grinding operations. Grinding of double curvature surfaces involves the use of both cylindrical and shaped wheels. The present paper considers the option of using cylindrical flap wheels. Depending on the curvature and width of the panel or skin under grinding, the possibility to select a wheel of desired width and shape has significantly expanded the technological capabilities of the installation. At the same time, there is a problem of selecting a specific flap wheel for the current processing conditions. The purpose of the work is to select the width of the cylindrical flap wheel for the turret head when grinding double curvature surfaces. The paper provides the research results of the influence of ground surface curvature for four values of the wheel width at the different values of hold-down (the amount of wheel deformation depending on its pressing to the machined surface). In order to evaluate the possibilities of efficient grinding of large size outer-forming parts, the analytical and graphic dependences between the values of hold-down deformation and panel curvature for specific values of the width of selected wheels are presented. According to the given data, a flap wheel of 100mm width can be used for processing panels with the curvature radius from 2.5 m or more at any value of flap hold-down (from 0.5 to 3.5 mm). A flap wheel with the width of 200 mm can be used for processing of panels having a curvature radius of more than 10 m in the considered range of flap deformation, while a flap wheel with a width of 300 mm can be used for processing panels with a curvature radius of more than 22.5.

large size outer-forming parts, grinding, turret head, flap wheel, deformation, selection of machining width