Papers by Author: Qiang Li

Abstract: In this paper, the high-strength steel three-dimensional roll forming production line prototype is studied. The dynamic differential equations of 3D roll forming machine mechanical systems are established by the principle of dynamic balance. The dynamic differential equations are solved out by using MATLAB with the engineering example finite element simulation data. The dynamic characteristics of the forming process of 1.5mm TRIP590 high-strength steel sheet are obtained by the System response. The results can help to improve the performance of the prototype mechanical systems.

Abstract: In order to optimize the craft parameter of cold roll forming, this paper puts forward a new method reflect the law between cold roll forming force and craft parameter. The method combines artificial neural network and finite element emulation for cold roll forming, and begins with analyzing the cold roll forming to decide the main factors that have an impact on roll forming force. According to the single factor experiment method, the paper establishes the roll forming emulation model to simulate, and a BP neural network is constructed with the sample data from the simulation.

Abstract: Outline extraction is the key technology of automatically generating roll trajectory in flexible roll forming process. The main purpose of this article is to extract outline from the grid lines of 3D surface in the STL (Stereo lithography) files. Using the functions of file stream and character manipulation provided by C++ Standard Library to read the STL file, using the GLUT(OpenGL Utility Toolkit) to build models, this article investigates the algorithms for outline extraction based on MFC Single Document Interface (SDI) Application.

Abstract: Trip steel is broadly used in automobile manufacturing with its high strength and enhanced formability. For the variable section parts with protrusion and hole, roll forming is a kind of feasible way to realize continuous parts manufacturing, In the paper, with deep understanding of roll forming process and reasonable simplification, the FEM model of a multi-step variable section roll forming of 600MPa trip steel parts with protrusion and hole is established to analyze the mechanics and the deformation characteristics of the forming procedure. Equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained to guide the design of the variable section roll forming product line.

Abstract: For the flexible roll forming of the control system, this paper introduces a method that machine vision bind to the flexible roll forming control system. The detection method for sheet metal forming is image acquisition, image processing and other means for the extraction of sheet metal forming in some time section contour curve. Compare extraction section contour curve with the moment theory section contour curve in the control system, get the deviation value and feedback to the control system that interpolation arithmetic to realize closed loop control.

Abstract: How to manufacture high accuracy, complex section, high strength steel products is the current challenge of flexible roll forming technology. This article introduced opening NC system application in flexible roll forming, both in software and in hardware. As the core module of the software system, the interpolation module was discussed. The article mainly focused on how to establish track simulation module. According to the algorithm, we calculated the roller displacement and rotation angle using VC++. At last the simulation processes and results were presented, which prove the trace interpolation algorithm is correct and feasible.

Abstract: Due to the complex motion control in flexible roll forming when processing the sheet metal with variable cross-section, it is required for high real-time and high precision control during the processing. Controlling servo motor by adopting the configuration programming is a common approach to achieve roller motion, but it will not be able or difficult to realize by the configuration programming for complex contour sheet metal without the rules such as hyperbolic, or the molding product in non-symmetric cross-section shape, etc. Based on the process characteristic of flexible roll forming and its motion control technology, this paper adopts the variable time-domain discrete interpolation control method to process the variable cross-section sheet metal. Experiments indicate that this control method provides a good operating method for the sheet metal forming with complex variable cross-section shape in flexible roll forming.

Abstract: In flexible roll forming, the horizontal movable sheet steel can be formed by controlling the servo motor to drive the multi-pass vertical movable roll. Only when the longitudinal movable distance of the roll in every pass matches exactly the contours of the sheet steel in time and space, the designated cross-section shape can be formed. Controlling the servo motor by applying the configuration programming is a common approach to achieve roll motion, but will not be able or difficult to realize by the configuration programming for complex contour without the rules such as hyperbolic, or the molding product in asymmetric cross-section shape, however, there are two other approaches such as simplifying the curves and using similar shapes to fit the process. As for the complex non-symmetrical curvature shapes, this paper adopts the variable time-domain servo motion control method to form the sheet steel. Experiments show that the variable time-domain servo motor control is a good motion control method for the sheet steel forming in complex cross-section shape.

Abstract: Flexible roll forming is a new forming process that produces parts with variable cross sections. This forming process is proposed to meet the need in the weight reduction of automobiles. With deep understanding of this process and reasonable simplification, the FEM model of a nine-step flexible roll forming of an ultra-high-strength steel bumper is established. In order to analyze the mechanics and the deformation characteristics of the flexible roll forming, equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained which can guide the design of the flexible roll forming product line.