1、PDF外文：http:/ 1 外文 文献 原文 Straightening Model and Prediction of Straightening Stroke of Precision Linear Guide Rail Abstract In order to improve the straightening precision of flexible automatic straightening machine, a new way of establishing straightening model and predicting str
2、aightening stroke is proposed based on bending experiment. In this paper, aiming at the LG series linear guide rails, the mathematical load-stroke model of press straightening process is established based on elastic-plastic theory. The stroke-deflection model can be obtained by simulating the bendin
3、g process of guide rails based on loading-unloading FEA analysis. And then the precision straightening model of predicting straightening stroke, which is describe as a simplicity formula, can be fit out based on establishing compensation knowledge base achieved from bending experiment and experiment
4、al data processing. The experimental results verify this methods feasibility. It will be helpful to the development of automatic straightening machines control system. Keywords: Straightening； Load-stroke model； Linear guide rail 1 Introduction Because of the external or internal force and tem
5、perature variation in work processing and transporting, metal bar may be bending or being distortion deformed easily. In order to obtain the high precision product, it should be straightened. The press straightening method, having big straightening force, best flexibility and high controllability an
6、d precision, could be applied to various degrees contraflexure of metal bar extensively. With the appearance of automatic straightening machine, the theory of straighten process have gradually becoming the focus of current precision straightening controlling research. However, improving the precisio
7、n of straightening theoretical model is still difficult. Reference 1 and 2 propose a way of establishing straighten theoretical model by controlling stroke, which is key factor of the straighten stroke accuracy calculation. Generally, the straighten stroke can be calculated according to the theory o
8、f elastic-plastic, FEM or empirical formula. But all of them have their limitation. At present, most studies focus on shaft and tubular bar, seldom on the irregular sectional. Besides, the straightening models rely overly on theory and have large calculation difficulty and lack practicability. The p
9、urpose of this paper is to establish precision straighten model and predict the straightening stroke which aiming at the LG series linear guide rails of irregular section. Firstly, the load-stroke model can be established by different conventional methods. Then the most important is the precision st
10、raightening model of predicting straightening stroke which is describe as a simplicity and precision formula can be fit out based on establishing compensation knowledge achieved from bending experiment and experimental data processing. Comparing these models, the precision straightening model will a
11、lso verify and modified the former. It will be helpful to the development of automatic straightening machines control system. 2 The Straightening Model Based on Elastic-Plastic Theory 2.1 Press Straightening Process of 3-Points Reverse Bending In the process of press straightening, linear guide rail
12、 can be divided into a number of single-arcs to do multi-step straightening. Take single-arc for example, straightening process is comprised of reverse bending phase and elastic springback phase.Fig.1. shows the load-stroke (F- ) curve model of straightening process2. In this figure, the loading pro
13、cess includes elastic deformation stage AB and elastic-plastic deformation stage BC, according to the simple law of unloading , the stage CD is considered elastic springback stage, so the line of AB and CD have the same slope K, point B is the yield point of elastic stage. If we have measured the in
14、itial deflection of guide 0, the location of point D will be defined, and then the location of point C which determines the corresponding straightening stroke c and straightening load Fc can be known. 2.2 The Mathematical Model of Straightening Process We do analysis of straightening process o
15、n the basis of plane assumption and ignoring the impact of Bauschinger effect due to the deformation of bending is relatively so small for span. Fig.2 Shows the cross-section diagram of LG series linear guide rail. The material of rails is GCr15 bearing steel, so the stress-strain model was assumed to be an ideal model for elastic-plastic materials. As this cross-section is similar to rectangle, we analysis it according to the theory of rectangular section while the actual sectional moment of inertia (I) should be calculated. According to Fig.1, the
