Theory Model, Simulation And Experiment Research On Bending Straightening Of Elevator Guide Rail

As a component-oriented, the guide rail straightness directly influences the stability and security of an elevator, especially on a high-speed elevator. With the rapid increase of high-rise buildings, the demand and the quality requirements for high-speed, high precision elevators are increasing. In order to improve the guide rail straightness, bend straightening is essential for processing operations. At present, bending straightening of elevator guide rail basically remains at a lower level, which mainly depends on workers'experiences, this state reduces the machining accuracy and efficiency of elevator guide rail greatly. So, the development of automatic straightener for elevator guide rail become an urgent issues, but the automation and digital straightening still lacks systematic theory support. This dissertation by coalescing the theoretical modeling, finite element simulation and experiment, theory and method for straightening the bending of elevator guide rail are researched.This dissertation is divided into 7 chapters:Chapter 1 gives a review of the current elevator guide rail machining technology based on the machining process. The origin and precaution of guide rail bending as well as the limits are clarified in this chapter. Then, the necessity of guide rail bending straightening is given. Based on the survey, present level of the research for guide rail bending straightening is brought up in chapter 1.In order to verify the bending deformation characteristics, chapter 2 obtains some characteristic parameters, such as the position of straightening pressure head and fulcrum as well as the initial bending curvature. It also focuss on the key problems in the guide rail straightening process, such as the bending point, the bending value and whether it needs to be straightened or not, which are mainly determined by human experiences. An automatic guide rail bending measurement system is developed in this chapter. The measurement system could provide a full length measurement and the bending value of the guide rail. The method for constructing bending curve and its mathematical expression based on the bending measurement data is presented in chapter 2. The statistical analysis for bending deformation has been done. Furthermore, the bending judging criteria are clarified, as well as the method to determine the position of straightening pressure head and fulcrum is given. In this chapter, calculation formula of initial bending curvature is presented as well. Briefly, chapter 2 solves problems such as the bending point, bending value and whether it needs to be straightened or not, which provides a foundation for the guide rail bending straightening.There are two bending forms in guide rails:the lateral bending and warpage. Obviously, the guide rail bending is a complex two-dimensional bending, which makes each of their straightening formula completely different. Therefore, analysis of the material model, stress-strain relationship, basic curvature relationship and curvature moment relationship based on elastic-plastic mechanics are presented in chapter 3. Considering that there are two kinds of guide rails:the trackless waist and waist rail, both of their straightening models and recurvation curvature formula are provided respectively. Furthermore, the straightening control parameters (mainly straightening stroke calculation formula) are presented in this chapter. Based on straightening stroke calculation formula, the straightening stroke corresponding to certain initial bending deflection could be calculated directly, which make the implement of bending straightening much more convenient. At last, an application example is given, and the error source is analyzed.As the warpage direction is a non-symmetrical section, and section dimension has a sudden change, so the bending straightening is much more complicated compared with lateral bending. In view of this, based on the analysis of waist rail warpage section features and its straightening characteristics, chapter 4 derives the straightening moment formula and straightening curvature formula in certain initial warpage for 4 different bending degrees, using stress-strain relationships in elastic-plastic mechanics. The relationship between recurvation curvature and initial curvature is presented as well, which lays a foundation for the warpage bending straightening. In chapter 4, in order to make the straightening work be carried out much more conveniently, further expression of straightening control parameters combined with warpage straightening theory and practices is presented. At the end of this chapter, an application of presented model is brought up to validate its feasibility. Analysis on model's error source is provided as well. At last, warpage straightening theoretical formula for trackless waist is presented under three different circumstances.Chapter 5 focused on the elevator guide rail bending straightening issues. Finite element simulation models for lateral bending and warpage are constructed based on ANSYS. Then, simulation is taken to analyze the process of lateral bending and warpage based on the presented model. By exerting a series of loadings, the corresponding pressure stroke and residual deflection of lateral bending as well as warpage could be obtained. Lateral bending and warpage straightening load-stroke curves could be get as well. Furthermore, curves from the experiment and curves form the model are compared to validate the effectiveness of the presented model. A modified model is given based on the guide rail straightening simulation data. That is to say, based on the simulation data of the stroke-deflection model, a modified model expression is provided. Straightening stroke could be obtained directly from the modified model. The computing speed and accuracy improved compared with the former model.Taking elevator guide rail as the object, chapter 6 conducted lots of experimental researched on lateral bending and warpage straightening problems. After the validation of finite element simulation on the straightening theoretical model, a feasibility verification of lateral bending and warpage straightening theoretical model is carried out based on the experiment data. Furthermore, a comparison of lateral bending and warpage straightening control parameters among the three manners such as theoretical model, FES and experiment are presented. At the end of this chapter, a prediction model and its expression of lateral bending and warpage are presented based on the experiment data.A conclusion of this paper is made and the prospect of further research in this area is presented in chapter 7.