| In the ship building industry, the anti-curve line method is widely used in frame bending. The method can be described that we firstly draw a curve on the frame, and then bend the frame until the curve is made to a straight line, and the frame is bent successfully. The NC Frame Bending Machine is widely used in the ship building industry. It drives the numerical control device through the NC cutting command, and bends the lank proximate matter into the original shape according to its original offset data. If we determine the original shape through the anti-curve line data, the commonality will be prompted.This paper sees the anti-curve line problem as a deformation problem. Based on the analysis of the frame model, we give two algorithms based on deformation. Firstly, we see the frame as the image. With the help of free form deformation, we give the image warping method based on the mean value coordinate. This method doesn't deform the frame directly but deform the control polygons firstly and implement the whole deformation. We can see the frame as a skeleton, and give the deformation method based on the IK (inverse kinematics) model. In this method, we choose the middle axle as the skeleton, and disperse the skeleton into the poly-line, build the IK model, and convert the problem into nonlinear multi-variant constrained optimization. The result of this method can be accepted in the frame bending. This method has been adapted for the project. The result of two or more sections of anti-curve line is not as good as one section of anti-curve line. It is necessary to study the approach to replace the multiple anti-curve lines with only one anti-curve line. In this paper, we implement the fitting between two or more sections of anti-curve line. This method is simple and fast but lack of enough proof.Finally, this paper gives the comparison of the results of the three methods, and analyses the problem of the algorithm. Additionally, the outlook of the problem is mentioned.
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