Study On Printing Key Technology Of Transmission Impeller Sand Core

As a kind of typical logistics engineering machinery,loaders are widely used in bulk materials,loading and unloading of tubular materials and other logistics areas.Among them,the transmission impeller blade is one of the key components in the loader drive system.At present,low pressure sand casting,as a traditional transmission impeller blade casting process,has the advantages of low cost and simple process,but its mold design and manufacturing cycle is long,and the manual mold accuracy is poor,etc.,has become the bottleneck of product update and R&D speed.3D printing technology is accurate,efficient and so on.It is one of the important research fields to solve the above problems.The paper aims to achieve 3D printing of transmission impeller core,the whole process of 3DP three dimensional printing and gluing sand mold technology is studied,and its reliability has been verified.Firstly,UG surface modeling and parametric modeling method are used to establish a three-dimensional model of impeller piece sand core which can be used for 3D printing and smooth surface matching;Then,a new scanning path planning algorithm is proposed,which can effectively avoid the "step effect" and reduce the number of nozzle switching,and it has been successfully applied to sand core printing;Finally,In this paper,the algorithm is digitally tested for reliability verification.The main work is as follows:According to the LG company's loader transmission blade size data,which are provided by LG company,by using the NURBS curve fitting function in Unigraphics NX(UG)3D design software,the section profile of the blade was fitted to the set of point coordinates obtained.The three-dimensional model of the blade is established.And the parametric modeling based on the feature is used to create the ring body of the sand core.A three-dimensional model of the impeller blade core for 3D printing can be obtained by subtracting the 3D model of the impeller blade from the core of the sand core.Aiming at the existing 3D scanning scanning path planning algorithm,and on the basis of STL model,equal thickness slicing is carried out;In this paper,a scanning path planning algorithm based on cobweb structure is proposed,and the offset spiral structure of spider web is adopted on the basis of contour bias scanning;The scanning path planning algorithm is realized by MATLAB programming.The design of 3D printing equipment,materials and printing methods,after the successful completion of the impeller sheet sand core printing,the high precision non-contact 3D scanner was used to scan the contour of the impeller sand core printed by 3DP three dimensional printing and gluing sand mold,and the collected surface data is imported into Geomagic Studio for point cloud processing and reverse modeling.The three-dimensional digital model of the casting sand core of the transmission impeller blade was modeled by Geomagic Qualify software and compared with 3D by UG,the error of sampling random points is analyzed by means of normal distribution function,error transfer accumulation function,Taylor series and partial derivative formula,and the surface accuracy is analyzed.Thus,the accuracy and reliability of 3DP three dimensional printing and gluing sand mold technology are verified.