Parameterized Reverse Remodeling Of Automobile Body Outlines Based On Siemens NX

The reverse design is an important technique in automobile body design process. Its core contents are outlines and surfaces quickly built by measured point cloud data. The body is a complex assembly. The reconstruction accuracy of holes and outlines has an important influence to the accuracy of vehicle assembling, the matching of the measurement coordinate system with the vehicle coordinate system and the quality of the subsequent surface modeling. Nowadays the mainstream CAD software and reverse engineering software provide fast automatic curve reconstruction function based on point cloud data. Through the point cloud data, they can automatically build a single curve. However, this method does not fully meet the needs of body reverse. In many specific application environments, engineers still have to use the tedious manual process to complete the remodeling of holes and outlines. The fundamental reasons are body holes are complex outlines composed of multi-stage different forms curves, among the curve segments there are complex geometric constraints and size associations, diverse distribution rules also exist among different outlines. Currently, a single curve reverse can not sufficiently reflect the interrelationships of outlines.This paper discusses the above issues and analyses the general methods of body outlines, holes reverse design. It also compares automatic curve remodeling and manual reverse design. For automatic curve remodeling, the holes constituted by accumulating single curve segments ignore the inherent correlations of the outlines. They can not fully meet the requirements of the body and parts reverse. The manual remodeling engineers understand their internal rules and distribution laws and have the ability to maintain the rationality of outlines. But they consume a lot of time doing the repeated adjustments to ensure the matching of outlines and measurement dates. This paper tries to trace the designer’s manual design process by automated manual process and improves the design efficiency under the guarantees of outlines accuracy and rationality.This paper is based on existing CAD platform, proposes embedding the design rules, the outlines inner relations and external relations into the parametric models. Take full account of the outlines area point cloud data distribution characteristics to replace designers manually modify by parameter iteration. Using optimization method to complete the complex outlines automatic remodeling. Replacing the existing curve remodeling by outlines remodeling, in order to ensure geometric relationships and parameter associations among the outlines curve segments.At the same time, the complexity and diversity of the body outline curves make it difficult to provide a direct mathematical solution for each remodeling case. But parameter optimization method based on the outline remodeling can avoid this problem and makes the curve&outline automatic remodeling module could cover a greater range of applications.This paper is based on Siemens NX software platform, uses UG/KF technology and UG/Open API interface for secondary development to achieve and verify above-mentioned visions. The application of this method and the corresponding software modules shows that the efficiency gets a huge upgrade by using automatically outline remodeling compared to manual operation under the premise of ensuring rationality and inter-related. And the parameterized results also provide the possibility of latter rapid design adjustment and design reusing.