Influence of machining process parameters on microgeometry during milling of curved shaped surfaces

Abstract

Purpose. Theoretical study of the conditions of contact of the cutting edges of ballnose end millswith a curved surface of parts during milling on computernumerically controlled (CNC) machines, determining the effective diameter of the cutting edge when machining sections of shaped surfaces that are inclined relative to themillingcutter axis, and evaluation of the influence of processing parameters on the size of surface micro-irregularities of the processed surface. The methods. The study is based on the use of analytical geometry methods in studying the theoretical geometric model of contact of ballnose end millswith curvilinear shaped surfaces of parts and the influence of machining process parameters on the micro-irregularitiesof shaped surfaces. Findings. The relationship between the effective diameter of the milling cutter and the diameter of the working part of the shapedmillingcutter, the depth of cut, the pitch between adjacent passes, and the angle between the cutter axis and the normal to the nominal surface of the part has been established.The obtained dependencies of the residual scallop height on the machined shaped surfaces on the cutter diameter and the pitch between adjacent passes make it possible to assign processing parameters for curved surfaces of parts while ensuring a given surface roughness. The originality. Functional dependencies were determined for calculating the effective diameter of the cutting edge of an ball nose end mills when milling sections of shaped surfaces that are inclined relative to the mill axis, and formulas were obtained for determining the residual scallop height. Practical implementation. Processing curved surfaces of parts,taking into account the angle of inclination between the milling cutter axis and the normal to the nominal surface of the part at the point of their contact,allows processing parts of proper quality and accuracy with minimal costs.The given formulas for calculating the effective diameter on the cutting edge of the ball nose end mills allow the technologist to assign an appropriate spindle speed when assigning the optimal cutting speed for the given milling conditions, which recommended by the tool manufacturer.