Contact Characteristic Research On Critical Parts Of Steel Ball Unfolding Structure

In steel ball surface defect detection device,expanding the sphere depends on the core part named unfolding wheel.But unfolding wheel is expensive,changes frequently and completely relies on imports.It greatly increases the cost of detecting.Hence the localization of unfolding wheel and the development of the steel ball detection equipment need to achieve urgently.This article studies comprehensive contact characteristics of steel ball and unfolding wheel from angle of contact form,contact deformation,contact stress and contact force,it provides an in-depth theoretical basis for unfolding wheel and the design of unfolding mechanism,and has important theoretical value and practical significance.In order to study the contact form of steel ball and unfolding wheel,the interaction process between asymmetric unfolding wheel and steel ball is analyzed according to the movement principle of unfolding entire surface of steel ball.Then discussing three possible contact models.Finally,the material properties of unfolding wheel is studied by means of FEI-Sirion scanning electron microscope experiment,establishing the theoretical foundation for contact characteristics research and material design unfolding wheel.In order to solve the contact deformation of the steel ball and unfolding wheel,firstly,discusses two problems existing in application of Hertz theory.Secondly,obtains the relative curvature radius and the equivalent curvature radius of spherical surface and cone surface at the initial contact points using smooth uncoordinated surface geometry.Finally,establishes contact deformation model of steel ball and unfolding wheel using Hertz formula.It provides a theoretical model for contact collision force research of steel ball and unfolding wheel and extends the application of Hertz theory in non-classical contact model.Based on the analysis of contact form,in order to obtain stress state within the range of contact deformation,firstly,determines tangential stress distribution oncontact area of steel ball and unfolding wheel according to research thought of Carter rolling contact theory.Secondly,uses Mc Ewen theory and the idea of narrow-band to calculate each stress components.Finally,obtains the stress component analytic formula of three-dimensional rolling contact based on the superposition principle,hence discusses influences which contact coefficient and friction coefficient have on each stress components in numerical simulation results.It provides a new idea method of studying three-dimensional rolling contact stress.In order to obtain the change process of contact collision force of steel ball and unfolding ball,establishes contact collision model describing the relationship between contact force and deformation based on Hertz theory.In ADAMS system dynamics software platform for secondary development,links subroutine of contact collision model for steel ball and unfolding wheel and solve this mechanical model,and does a simulation comparison analysis with impact model.It verifies the rationality of contact collision model,reveals the unfolding process of spherical surface from mechanical angle,discusses the influence on detecting system from pressing force,and provides a theoretical basis for the mechanical design of unfolding mechanism.