Abstract: In the process of product design and use,the performance analysis and maintenance of the product requires its 3D CAD model.In the design process,designers usually use AutoCAD to design the 2D engineering drawing.How to convert the 2D engineering drawing into 3D model in a short time is the key to shorten engineering cycles time and rapidly maintain product.Based on the knowledge of B-spline curve and B-spline surface theory,this paper proposed a process of automatically constructing 3D CAD model from 2D engineering drawing by using surface fitting technology,and proposed a data point screening optimization algorithm to reduce the amount of used data points.It solves the problem that the manual conversion from the 2D engineering drawings to the 3D CAD model is time-consuming and labor-intensive,and shortens the cycle of product development.Taking a ship model as example,the paper validated the feasibility of the method for the construction of model.

Key words: 2D engineering drawing, 3D CAD model, B-spline curve, B-spline surface, Fitting technique of surface