Principle of Multi-roller Straightening Process and Quantitative Resolutions of Straightening Strategies

The multi-roller straightening process of section steel is analyzed by the springback theory of small curva- ture plane bending. The theoretical analysis results prove the curvature unification in straightening process and clear- ly reveal the principle of the multi-roller straightening process. The principle can be described as~ the initial curva- tures are reduced by several times anti-bendingl meanwhile the initial curvature differences are diminished and the residual curvatures are unified~ finally, the member after curvature unification is straightened by the last anti-ben- ding. With the plastic region ratios becoming larger, the initial curvatures are more easily unified in straightening process. Based on the plastic region ratios and the required number of roller systems for unifying the initial curva- tures, the large deformation straightening strategy and the small deformation straightening strategy are redefined. The new definition provides an important theoretical basis for setting reliable reduction rules. Through the theoretical analysis results, a new straightener design philosophy is proposed to improve the straightening quality and further increase the adjustment precision as well as the flexibility of the last roller system. The adjustable end roller emerges as the times required, achieving a good effect in practical application.

Feasibility of Synchronously Straightening Working Line of Adjacent Open-cast Mines

Taking Heidaigou Open-cast Mine and Haerwusu Open-cast Mine in Zhungeer mining area as the research objects,this paper deeply analyzes the current mining status of the two mines.Based on the existing working line length,mining technology,transportation system,equipment configuration,transportation access and many other factors,it systematically discusses the feasibility of straightening the working line of adjacent open-cast mines.Through in-depth theoretical analysis,it establishes the mathematical model of impact indicators and cost calculation,and it is concluded that the work line straightening can be technically achieved.However,from the perspective of economic benefits,straightening the working line does not show obvious advantages.

RESEARCH ON STRAIGHTENING TECHNOLOGY CAM SYSTEM

Automatic straightening process is a nonlinear process, and affected by manyfactors. The straightening technology CAM system has been designed and built up to straightenshafts, which mainly consists of the straightening technology's database and the model ofstroke-controlled precise straightening calculation model. The operational test of the CAM systemhas been passed.

Innovation in the Computing System of Straightening Force

Currently in China, the computing system of the straightening force of the six-rollers straightening machine generally follows the traditional computing system. The force status of the traditional computing system for the straightening force deviates far away from the actual force status of the roller system in the six-rollers straightening machine. In the traditional system, the computing model of the straightening force of the six-roller straightening machine was based on the roller shape of hyperbola, which led to the length of the contacting line between the tube and the straightening roller to be excessively short, i.e., only 0.1~）.2 of the length of the roller. Thus the constructed computing system has relatively large difference from the actual measured result. To solve the above problems, flattening straightening and bend straightening are analyzed on the basis of materials mechanics and bend beam theory, the roll er shape using the envelope method of A.I4.~e：mKoB is generated, and a new computing system for straightening force in six-rollers straightening machine is built. The roller shape of the straightening roller, on which the new computing system for the straightening force is based, is designed according to the envelope method under the condition of ideally full contacting between the tube and the roller body of the straightening roller, therefore the new computing model accords with the practical status of straightening force. According to the comparison of the new computing system with finite element method and the actual measured result of straightening force, it has been proved that the computation accuracy of the new computing system for straightening force satisfies the practical requirements of engineering. New six-rollers straightening machines are designed and manufactured according to the new calculation system, and the new machines not only have higher precision and quality, but also have adopted the force sensor and computer and combined with the new computing system for straightening force to realize the fully automatic adjustment of the straightening machine. The new six rollers straightening machine have obtained notable economical and social benefits.

Longitudinal crack on slab surface at straightening stage during continuous casting using finite element method

Deformation behavior of slab at the straightening stage during continuous casting was simulated by the explicit dynamic finite element method,and the stress distribution along the width direction of the slab and its change regularity at slab center during continuous casting were obtained.The influence of distribution and change of stress on the propagation of longitudinal cracks on slab surface was discussed.The results show that the tensional stress appears on slab surface at the inner arc side and the compressive stress appears on slab surface at the outer arc side at stages 6-8 in straightening zone during continuous casting.Longitudinal cracks generally appear on slab top surface and do not appear on slab bottom surface,which are also observed in industry.

Multi-point flexible straightening process by reciprocating bending for metal profiles

A multi-point flexible straightening process characterized by reciprocating bending is proposed.Specifically,the process is analyzed in terms of deformation mechanism and verified by numerical simulations and physical experiments of the straightening of a series of metal profiles with different materials and initial shapes.Further,the relationship between the bending radius and the times of reciprocating bending required to unify the curvature is discussed,and the distribution of residual stress after straightening is analyzed.The results show that the reciprocating bending process can eliminate the difference of the initial curvature,make the curvature of each section tend to be uniform;the times of reciprocating bending to reach the uniform curvature decreases with the decrease of bending radius.The straightness of the straightened profile obtained from the experiment and simulation is less than 0.2%,demonstrating a good feasibility of this method.

The Role of Corrugation Die Parameters on the Mechanical Properties of Aluminum Alloy (AA 5083) Processed by Repetitive Corrugation and Straightening

The microstructure and mechanical properties of aluminium alloy (AA 5083) processed through Repetitive Corrugation and Straightening (RCS) was studied. The RCS process consists of corrugating a flat specimen with a pair of systematically grooved dies and straightening was done with two parallel flat dies. The aluminium samples were subjected to RCS process using two different die: Die I-semi grooved die with breath = height = 5 mm and θ = 30。 and Die II-semicircular profile with radius = 10 mm. The specimens were subjected to maximum 8 passes for die I but the other one went upto 14 pass. The grain refinement was studied from the microstructure examination using TEM. The mechanical properties such as tensile strength, hardness and the grain size were compared. The tensile strength and hardness were found increasing with respect to the number of passes. The tensile strength increased 25% in the sixth pass when compared to the parent material. But the strength and hardness values were reduced at 8th pass due to the surface cracks. The TEM studies showed that the Die-I is superior to Die-II in terms of grain refinement.

Evaluation of straightening capacity of plate roll straightener

Straightening machine is widely used for improving the quality of the defective mild steel plates.In general,the capacity of straightening machine is affected by material properties,the initial shape of the incoming plate and the plastic ratio.The mechanics model describing the capacity of the machine was developed.The deviation of the straightening capacity curves was studied.Then,the presented model was evaluated by comparative study to filed production data.Finally,the influences of overstretch,straightening speed,strengthening coefficient,elastic modulus,width of the plate on the straightening capacity were studied.It is convenient to determine whether the plate can be straightened or not by a series of straightening capacity curves.The straightening speed,width of the plate and elastic modulus of the material are more sensitive to the straightening capacity than the strengthening coefficient.

The mathematic model of tension straightening process of magnesium alloy and experimental validation

The stress-strain curve of bending bar and the stress relax curve of AZ31 was obtained by a tension test using Gleeble-1500.The tension straightening process mainly consisted of the elastic loading-I and unloading stage,the elastic loading-II and unloading stage,and the elastic-plastic loading stage,which were based on the stretch force change during straightening.The circular bar straightening under one-dimensional bending was investigated and assumed to be linear strain-hardening elastic-plastic material.According to the elastic-plastic mechanics theory,the mathematical displacement-force model of a tension straightening process established,on which was based,the predicted displacement of tension straightening for various original deflection was calculated.The tension straightening experiment for AZ31 magnesium was conducted under the guidance of the predicted displacement.The experiment results present good straightness when there is a stress relaxation phenomenon or the temperature of tension straightening is 25℃.

Optimal Driving of Large Belt Conveyor with Multi-roller Variable-Frequency Drive

in this paper, an electromechanically coupled mathematic model of multi-roller driving system for belt conveyor is set up, and the computing equations for dynamic displacement and dynamic tension of the conveyor are also formulated when the hoister is used for straining. Based on the belt conveyor of main inclined shaft in Chengzhuang coal mine, the driving torque, driving power and starting-speed characteristic of each electric motor are studied and measured when multi-roller variable-frequency drive (power distribution 2∶1) is used. The optimal control and the optimal starting-acceleration of the multi-roller variable-frequency drive are determined by a large number of industrial experiments and theoretical calculations.

A Solution of Drawing Straightening Roller Curve by Conjugate Revolving Quadric Theory

Based on the theory of conjugate revolving quadric theory,the analytic method of calculating the straightening roller curve in the procedure of straightening the bar has been given. Meanwhile,the equations,which describe roller curve and the longitudinal section,are given and simulated in computer. A brief method of designing and drawing the straightening roller curve is introduced.

Analytical-Numerical Modeling Approach for Calculation of the Structural Distortions after Welding and Thermal Straightening

The analytic-numerical hybrid model for calculating welding distortions in large welded structures is presented. Objective of the analytical model is the calculation of the plastic strains and their distribution after welding and thermal straightening process. The consideration of the essential physical relations is put into discussion. Afterwards the obtained plastic strains by the analytical calculation are loaded on an elastic FE-model of the structure and the distortions of the whole structure are predicted. The consideration of welding and thermal straightening scenarios and the assembling stages is done by taking into account the intermediate variation of the strain state at every processing step. The model is intended to be used for solving industrial tasks, i.e. intending acceptable precision and calculation time as well as low simulation costs. The application of the model is demonstrated on structures with many welds and straightening spots.

Surface morphology and mechanical properties of the nanocrystalline tensile-straightening rollers treated by the ultrasonic particulate peening

Tensile-straightening rollers of a pickling line at Baosteel are surface nanocrystallined by the ultrasonic particulate peening(USPP)method.Surface morphology and mechanical properties of the rollers were characterized by scanning electronic microscope(SEM),a roughness meter and a microhardness tester.Results have indicated that there are a lot of randomly distributed impact pits on the surface after the USPP and that surface roughness can be adjusted within a range of Ra 1.5-2.5.The grain size in the surface layer is refined significantly.The microhardness of the surface layer can reach 920 HV after the nanocrystalline treatment.The dependency of the two main influencing factors,i.e.the working gas temperature and pressure,on the surface roughness and microhardness is presented.

Possibility of a Straightening Flow-Meter by Using Woven Screen

In this paper, the possibility of the flow rate measurement for a circular pipe flow by using a wo-ven screen with the property of straightening un-uniform flows is discussed. The resistance coefficient and the flow rate coefficient are estimated from the pressure difference caused by the woven screen under the experiment ranges of the wire Reynolds number, Red = 2.2 × 102-1.8 × 103, and of the open area ratio, β = 0.28-0.65. As a result, the resistance coefficient decreases and the flow rate coefficient increases as the wire Reynolds number Red or the open area ratio β increases. In addition, both coefficients are not affected by the difference between uniform and turbulent pipe flows approaching the woven screen. Therefore, the possibility of a flow-meter having the property to straighten the un-uniform flow is expected.

Group Multi-Role Assignment With Conflicting Roles and Agents

Group role assignment(GRA)is originally a complex problem in role-based collaboration(RBC).The solution to GRA provides modelling techniques for more complex problems.GRA with constraints(GRA+)is categorized as a class of complex assignment problems.At present,there are few generally efficient solutions to this category of problems.Each special problem case requires a specific solution.Group multi-role assignment(GMRA)and GRA with conflicting agents on roles(GRACAR)are two problem cases in GRA+.The contributions of this paper include:1)The formalization of a new problem of GRA+,called group multi-role assignment with conflicting roles and agents(GMAC),which is an extension to the combination of GMRA and GRACAR;2)A practical solution based on an optimization platform;3)A sufficient condition,used in planning,for solving GMAC problems;and 4)A clear presentation of the benefits in avoiding conflicts when dealing with GMAC.The proposed methods are verified by experiments,simulations,proofs and analysis.

Multi-role Remotely Operated Marine Surface Vehicle

Development of man-packable,versatile marine surface vehicle with ability to rescue a drowning victim and also capable of carrying mission specific sensor is explored.Design thinking methodology is implemented by using existing equipment/platform with the addition of external attachment to make it a functional product.Iterative prototyping process with extensive testing to achieve user-centric solution.Individual prototypes and their possible sub-configurations with their integration and characteristics are studied and compared with numerical model,inferences obtained are utilised to improve for the next iteration.A novel hinge-clamp assembly enables this marine surface vehicle to operate in the event of an overturn,this phenomenon is further studied with the aid of a mathematical model(Pendulum in a fluid).This research project aims to demonstrate a multi-role unmanned surface vehicle.

On multi-role effects of teachers in College English teaching

The paper first introduces the multi-roles of College English teachers, from the knowledge instillers to the designers and organizers of classroom activities, the participants of learning English, information counselors and emotional supporters, and the models of morality. Based on this, the paper makes a detailed analysis of the multi-role effects which can not only stimulate students＇ creativity and improve their self-learning ability, but also adapt to the reform of College English teaching.

大型曲轴圆角滚压矫直工艺优化研究

长度为1.6~8 m的大型曲轴在制造加工过程中,由于热变形和冷却不均等原因会造成二次弯曲,需要通过圆角滚压矫直工艺进一步改善主轴颈和连杆颈中心的跳动量。为了解决大型曲轴跳动量超差现象并提高加工效率,旨在以16V型大型曲轴为研究对象,基于已有结论和建立优化数学模型,运用NSGA-Ⅲ算法和PlatEMO平台对圆角滚压矫直工艺实行了多目标优化,并结合TOPSIS决策方法计算了Pareto解集的贴近度指数,根据指数排序结果进一步选择每次滚压矫直的最佳方案,实现了工艺参数(滚压力、滚压角度范围)的优化。优化结果与有限元仿真结果具有较高的一致性,有效降低了16V型大型曲轴各主轴颈的矫后跳动量和减少了滚压矫直的次数,确保曲轴性能达到要求。

鄂西地区颚鹤页3井钻探施工技术

页岩气参数井颚鹤页3井位于湖北恩施湘鄂西褶皱带宜都-鹤峰复背斜鹤峰向斜,钻探的主要目的是主探二叠系大隆组台盆相沉积页岩气,兼探栖霞组混积陆棚相沉积页岩气,设计井深2300 m,完钻井深2326 m。本文介绍了颚鹤页3井的钻探施工情况,针对地表浅层嘉陵江组的失返性漏失处理,防斜打直弯壳体螺杆钻具组合设计,孤峰组和茅口组高硬度硅质灰岩钻头选型等方面开展研究,提高了钻进效率,完成了中国地质调查局自主组建钻井队伍实施的第一口页岩气参数井,获取了目的层岩心实物资料,实现了鄂西地区二叠系大隆组页岩气、栖霞组油气调查新发现,拓展了鄂西地区二叠系页岩气勘探新区和新层系,对鄂西地区页岩气调查评价与开发提供了重要技术支撑。

降低6061铝合金宽幅加筋板型材平面度的工艺研究

研究了高温在线整形工装和仿形拉伸工装对6061铝合金挤压宽幅加筋板型材平面度的影响。结果表明,通过高温在线整形和采用仿形拉伸垫块进行拉伸矫直,可有效降低6061铝合金挤压宽幅加筋板型材的平面度。相比之下,高温在线整形对降低宽幅加筋板型材平面度的的效果比采用仿形拉伸垫块更明显。高温在线整形是利用铝合金在高温状态下硬度低、易矫直的特点,通过施加外力的方式对高温状态下的型材进行在线整形,使宽幅加筋板型材获得良好的平面度,同时配合使用仿形拉伸垫块进行拉伸矫直,生产的6061铝合金挤压宽幅加筋板型材可满足客户对平面度的要求。