Application of 3D FEM-slab method to shape rolling

In this paper, a complex model combining the simplicity of the slab method and accuracy of the finite element method was developed to save CPU time. When applied for the shape rolling, the deformation zone in the billet was divided into several proper slabs according to the shape of boundaries, in which each slab must match the force equilibrium along the longitudinal direction. Then, FEM was used to calculate sequentially the velocity field, metal flow, stress and strain distribution for each slab. By using only one slab in each iteration, the iteration range of traditional FEM was significantly reduced. Therefore, the memory capacity and computational time can be significantly reduced. Compared with traditional FEM, the results of this complex model were acceptable, verifying that the model proposed in this paper is an effective method.     

我国建轮胎试验场条件已成熟

目前测试手段不完备严重阻碍了国内轮胎企业自主创新的能力,对此,中国橡胶工业协会会长范仁德日前表示,从现实看,建设轮胎试验场对整个轮胎产业的发展非常必要,没有试验手段,本土轮胎很难打入汽车配套市场,对将来的出口也非常不利。目前国内建设轮胎试验场的条件已经成熟,应发挥企业、政府和国内外投资集团的作用,共同促成试验场建设。     

基于雅可比旋量法的实际工况公差建模

计算了加载时工作零件的变形量,并将其转变为雅可比旋量修正量,通过对雅可比旋量公差模型在实际工况下的扩充与修正,建立了基于雅可比旋量和实际工况的装配体公差数学模型,以此定量计算实际工况对产品工作性能及公差设计的影响。通过将此方法在某齿轮泵装配体的公差设计中的应用说明了该方法的有效性。     

非光滑结构在轮胎降噪声抗滑水中的应用研究

运用ABAQUS对具有横向花纹沟的轮胎滚动进行仿真,提取轮胎沟槽表面在轮胎接地过程中随时间的变形曲线。建立单个在花纹沟表面带有非光滑结构的横向花纹沟及其周围的空气域模型,在沟槽表面加载从ABAQUS中提取的变形曲线,利用FSI方法分析了非光滑结构对泵吸噪声的影响,并利用CFD对带有非光滑结构的沟槽进行滑水分析。分析结果表明在花纹沟壁上适当添加非光滑结构,可以达到既降噪又提高滑水速度的目的。     

Modal characteristics according to the tip shape and assembly condition of the turbine blade

To determine the reliability of a 5 MW gas turbine engine blade in high cycle fatigue (HFC) fracture being developed by Doosan Heavy Industries & Construction Co., Ltd., resonance characteristics are verified based on the turbine blade tip shape and assembly condition. In this study, the modal characteristics of compressor and turbine blades are investigated, and a Campbell diagram is established. During the preliminary study, modal analysis and holographic modal test of the first-, fifth-, and tenth-stage compressor blades were performed. Based on the preliminary study result, the natural frequency and Campbell diagram analysis for the turbine blades were performed. This research compared and verified the modal characteristic and resonance stability according to the tip shape and assembly condition of the blade to prevent any HCF fracture. In conclusion, the resonance stability of the shrouded blade is far superior to that of the squealer blade. Suitable assembly conditions must be applied.     

浅谈电子称重仪表现场应用中的电磁干扰及其防护

在各种工业生产环境下,电子称重仪表的广泛应用,都需要电子称重仪表有着可靠的性能。这也给各个仪表生产商提出了新的要求,即在恶劣的电磁环境下,仪表能否抵抗外界的电磁干扰而正常可靠的工作。本文列举了三种工况下最常见的电磁干扰并对其进行分析,并提出一些简单有效的防护措施,供各位读者参考。     

Study on the manufacturing process of precision linear guide rail through shape rolling and shape drawing

Guide rails are one of the most important components in terms of equipment because the quality of the linear rail in-fluences on the precision linear motion. For long rails used in the guide rail, high dimensional accuracy as well as a cross-sectional shape is required. As a production method of guide rail, drawing process is mainly used. But, the shape rolling process is open used for the pre-process of the other metal forming process such as forging, extrusion, and shape drawing. The shape rolling process is one of the most effective processes which can make long products with constant irregular cross-sectional shape. Therefore, the tool shape is a very important process variable to obtain the required final product. The objective of this paper is the design of roll shape of the rolling process to produce the initial material with irregular cross sectional shape for shape drawing. Also, the die shape of the drawing process is determined to satisfy the dimensional accuracy of the final product. In this study, FE-analysis and artificial neural network (ANN) were applied to achieve the objective. Further, shape rolling and shape drawing experiments were performed to verify the result of FE-analysis. From results, it was possible to design the roll shape of shape rolling process effectively.     

An easy way to measure surface free energy by drop shape analysis

The drop shape analysis is a conventional method to evaluate wettability and surface free energy. The analysis of drop profile is commonly used for the contact angle measurement between the liquid drop and sample surface.In many cases such as confined surfaces, it is difficult to carry out this measure, therefore it is necessary to evaluate the shape of the drop from top view point.The aim of this work was to develop a procedure in order to measure wettability and surface free energy values by means of the analysis of the drop shape from top view point. Starting from Tadmor equation, a polynomial function was obtained to correlate the drop diameter to its contact angle on a flat horizontal sample surface.In addition, analyses were carried out in order to study the shape of liquid drop varying the tilt of sample surface. In this case was shown a correlation between the tilt grade and the maximum characteristic lengths (parallel and orthogonal to pitch) of a drop shape on a tilt surface sample.Using the maximum characteristic lengths and a polynomial function previously obtained, it is possible to establish values of pitch, surface free energy and wettability of sample surface.In order to confirm the developed procedure, tests on three different materials have been performed obtaining these three performance indexes.All results obtained by means of this alternative analysis have been compared and corroborated by the classical method using the contact angles of the drop analyzed from a lateral view.     

Fault diagnosis of roll shape under the speed variation in hot rolling mill

The metal processing system usually consists of various components such like motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is therefore necessary to diagnose the faults of the components to detect and prevent system failure. Especially, the defects in a work roll are critical to the quality of strip. It is especially difficult to detect faults of a roll by using the existing frequency analysis method if the speed of the roll is changing. In this study, a new diagnosis method for roll eccentricity under the roll speed changes was developed. The new method was induced from analyzing the rolling mechanism by using rolling force models, radius-speed relationship, and measured rolling force, etc. Simulation results by using the field data show that the proposed method is very useful.     

HQ管降噪法在轮胎降噪中的应用分析

运用ABAQUS进行了具有横向花纹沟槽的轮胎滚动过程仿真,提取横向沟槽壁面在轮胎接地滚动过程中位移随时间的变化曲线。进而建立了单个横向花纹沟槽和其周围的空气域模型,对沟槽壁面施加滚动过程中的位移变形边界条件来模拟轮胎的滚动。在此基础上,利用HQ管降噪法对花纹沟噪声进行降噪探索。分析结果表明在花纹沟旁添加不同结构尺寸的HQ管结构可以达到降噪的目的。     

基于模糊集相似度量的装载机臂方案选择方法

描述了模糊集之间的相似度量与加权相似度量方法,根据模糊集之间的相似度量提出了装载机臂方案的选择方法。在臂部机构方案选择中,模糊集之间的相似度量是评价机构设计方案接近期望方案（理想方案）的度量,相似度量值越大,机构设计方案越接近期望方案。通过实例阐明模糊集之间的相似度量在装载机臂的方案选择中是可行的。     

A study on the fault diagnosis of the 3-d roll shape in cold rolling

The metal processing system usually consists of various components such as motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is, therefore, necessary to diagnose the faults of the components to detect and prevent a system failure. Especially, the defects in a work roll are critical to the quality of strip. In this study, a new 3-D diagnosis method was developed for roll shape defects in rolling processes. The new method was induced from analyzing the rolling mechanism by using a rolling force model, a tension model, the Hitchcock’ s equation, and measurement of the strip thickness, etc. Computer simulation shows that the proposed method is very useful in the diagnosis of the 3-D roll shape.     

Prediction model of the exit cross sectional shape of workpiece in round-oval-round pass rolling

A reliable analytic model that predicts the surface profile of the exit cross section of workpiece in round-oval (or oval-round) pass sequence is established. The presented model does not require any plasticity theory but needs the only geometric information on workpiece and roll groove. Formulation is based on the linear interpolation of the radius of curvature of an incoming workpiece and that of roll groove in the roll axis direction when the maximum spread of workpiece is known beforehand. The validity of the analytic model is examined by hot rod rolling experiment with the roll gap, specimen size, design parameter of oval groove and steel grade changed. Results revealed that the cross sectional shapes predicted by the model were in good agreement with those obtained experimentally. We found that the analytic model not only has simplicity and accuracy for practical usage but also saves a large amount of computational time in comparison with finite element method.     

A numerical method of obtaining the deformed shape of the roll in the cold rolling process

A numerical method which determines the shape of an elastic roll when the pressure distribution is known, is described. The method uses the principle of superposition, by replacing the pressure profile by equibased overlapping isosceles triangles whose individual deflection profile are known. The results show that if narrow-gauge steel strip is rolled, considerable elastic distortion of the roll results, it being quite different from the normally assumed circular arc.     

采用ABAQUS/Explicit分析滚动轮胎与变形地面相互作用

建立三维土壤弹塑性模型与轮胎模型,通过试验验证模型的可靠性,并用显示算法计算滚动轮胎与变形地面间接触时的相互作用,获得了滚动轮胎与地面接触时力与变形情况。有限元计算结果表明,此方法可以有效地分析轮胎与变形地面相互作用的问题。     

在电机转轴图样上如何正确标注力学性能

本文对电机转轴图样上标注的力学性能的不同含义作了解释，对在相同热处理工艺条件下，不同截面转轴坯料上的力学性能差别作了简述，以45钢为例，介绍了在转轴图样上以规定轴坯直径，代表力学性能的较精准的表示方法。     

The filtering method to calculate the transmission characteristics of the low-pass filters using actual measurement data

The Gaussian filter and spline filter are low-pass filters used in surface roughness estimation methods, and their transmission characteristics are well known. However, the transmission characteristics of the Gaussian filter and spline filter used at actual sites may not be in agreement with their theoretical characteristics. Generally, the spline filter is used with an open profile. Although the transmission characteristics of the periodic spline filter are well known, these transmission characteristics are not those of a nonperiodic spline filter used with an open profile. In the case of a Gaussian filter, the filter width of the theoretical transmission characteristics is ∞. However, a Gaussian filter of filter width λ_c is used at actual sites. This fact is a major problem. To solve this problem, it is necessary that the transmission characteristics of a low-pass filter are obtained from actual measurement data and the filter output. However, it is not possible to calculate the transmission characteristics from actual measurement data owing to the end effect and the discontinuity at each end of the data, etc. In this paper, we propose a new method for exactly calculating the transmission characteristics of a low-pass filter. This method involves the process in which the open profile is considered as a closed profile by repeating it periodically. The transmission characteristics of a nonperiodic spline filter and a Gaussian filter (filter width λ_c) used at actual sites were confirmed by the proposed method. The transmission characteristics of the Gaussian filter of filter width λ_c were almost the same as the theoretical characteristics. However, the transmission characteristics of the nonperiodic spline filter were considerably different from those of a periodic spline filter with well-known characteristics. Moreover, the transmission characteristics of the nonperiodic spline filter were found not to be unique.     

考虑接触特性的滚动轴承系统建模与仿真分析

根据Hertz接触理论和滚动轴承功能原理,以SKF6208深沟球轴承为参考,在ADAMS/View软件环境下设计建立了基于Impact函数的滚动轴承多体动力学仿真模型。通过实体接触条件下的轴承运转过程动态仿真分析,计算获得了滚珠与内圈、外圈及保持架之间的接触力动态分布规律。指出:轴承系统在启动瞬间(0~0.22 s)存在一定滑动,且接触力变化频率较大;进入滚动阶段(0.22~0.4 s)后,接触力变化频率减小,且呈周期性分布。仿真结果验证了滚动轴承的启动打滑现象,符合实际运行工况。为深入研究滚动轴承系统的接触机理及动态载荷提供了技术参考。