钢带缠绕预应力模具与制造设备

介绍了一种新型的钢带缠绕预应力模具,由高强度钢带缠绕层、模芯、模具衬套等组成.提出了一种钢带缠绕预应力模具制造设备及其控制方法,由开卷机构、夹紧机构、张力检测机构、缠绕机构、旋转编码器装置和电气控制系统等组成.设备采用双电动机式变张力缠绕系统、模块式组合机身结构和闭环控制技术,可实现预应力模具钢带缠绕制造过程中缠绕张力的自动控制.     

钢带缠绕预应力模具变张力模糊控制

针对钢带缠绕预应力模具缠绕工艺中变张力控制问题,分析了影响张力控制稳定性的主要原因,提出了参数自整定模糊PID控制方法,设计了模糊控制器.在Matlab/Simulink环境下,建立了钢带缠绕预应力模具缠绕控制系统仿真模型.在相同条件下,对比了采用参数固定的常规PID控制和采用参数自整定模糊PID控制的张力控制效果,验证了模糊PID控制在改善系统动态和稳态性能方面的优势.     

钢带缠绕预应力模具缠绕过程的数值模拟

针对钢带缠绕预应力模具的缠绕过程,开展了定张力条件下缠绕过程的数值模拟,解决了模拟中出现的壳单元接触、沙漏现象、钢带抖动等方面的问题.根据研究结果发现,随着缠绕层数的增加,模具表面预紧力增长的速度减小;预紧力在轴向方向分布具有不均匀性,中间位置数值最大,由中间向两端逐渐减小,存在端部效应;圆周方向预紧力出现波动,且波动随缠绕层数的增加愈加剧烈;模具内表面节点径向位移比外表面大.     

钢带缠绕预应力模具的疲劳设计方法

基于拉美公式、欧拉公式和疲劳设计理论,开展钢带缠绕预应力模具的疲劳设计研究,确定出合理的缠绕预紧力、缠绕层数和缠绕张力.分析工艺参数对疲劳设计果的影响规律,发现缠绕预应力随模具负载增加呈线性增加,预应力值增加的速度随着缠绕层数的增加逐渐变小;增加许用安全系数将导致预应力和缠绕层数增加;摩擦系数越小所需的钢带层数越少;钢带越厚缠绕层数越少.     

高强度高刚度钢带缠绕预应力模具

基于精密冷锻和人造金刚石合成等高负载条件下材料加工工艺对模具强度、刚度提出的高要求,深入分析了传统年轮式预应力模具的结构与存在的问题,介绍了钢带缠绕预应力模具的特点与技术优势,阐述了钢带缠绕预应力模具设计的基本原理与方法,研制了钢带缠绕预应力模具制造专用设备,提出了缠绕张力的产生原理与控制方案.     

缠绕垫片钢带压缩性能研究

应用有限元法研究缠绕垫片钢带在轴向压力下的压缩性能,得出钢带直径和角度α对钢带的影响规律。结果表明,角度α为45°直径为100 mm的钢带在相同轴向压力下,V形钢带的压缩量最大,其他结构钢带的压缩量不足V形钢带的1/2,钢带角度α为45°时钢带的压缩量随钢带直径的增大而增大,并在直径达到100 mm后趋于稳定值;在其他结构参数一定时,钢带的压缩量随钢带角度α的增大而增大,除M形钢带外,各钢带随角度的增大其轴向承载能力也减小。     

钢带焊接M形保持架工艺及模具

介绍M形保持架采用钢带焊接的新工艺，对焊接口的兜孔尺寸及形状进行了特殊处理，通过试验确定焊接时间和电极材料。介绍了模具调整要领。     

大型承载框架钢丝预应力缠绕技术研究

针对重型装备超大超重零部件预应力钢丝缠绕施工的问题,研究设计了1种自适应缠绕机器人,能够实现零部件外形自适应、变张力缠绕自适应以及排线自适应等3项功能,并在360 MN垂直挤压机制造中得到成功应用.     

缠绕垫片成型钢带压缩性能分析

建立了缠绕垫片成型钢带受轴向压缩时的力学模型，对几种成型钢带的压缩变形进行了理论计算，并进行了分析讨论。     

Experimental measurements of load and strip profile in thin strip rolling

Experiments are described in which plasticine strips are rolled using elastomer rolls. Conditions cover the range from “thick strip” behaviour, in which roll elastic deformations are small, to “thin strip rolling”, in which elastic deformations of the rolls are very significant. Results provide the first direct experimental confirmation of the thin strip rolling model proposed by Fleck et al. (Proc. Instn Mech. Engrs B206 (1992) 119–131). Strip profiles clearly show a short region of reduction at the inlet to the bite and a central region which is relatively flat, in accord with the theory. The profiles do not however show a short region of reduction at the exit as predicted. For intermediate strip thicknesses the measured loads are in reasonable agreement with theory. For the thinnest strips, although the form of the dependence of load on reduction and inlet strip thickness is as predicted by theory, the measured loads are almost an order of magnitude lower than predicted. It is suggested that this is caused either by differences between the assumed rigid–perfectly plastic strip and the real constitutive behaviour of the plasticine, or by errors in treating the rolls as elastic half-spaces, an approximation which is accurate for industrial metal rolling, but is not good for the conditions of these experiments.     

Optimal positioning of irregular shapes in stamping die strip

The nesting of two-dimensional shapes is a common problem, where raw material has to be economically cut. As for the single-pass single-row strip layout, several algorithms, based on established methods, have been proposed. Moreover, it should be noticed that the optimum layout should also consider a few constraints, like grain orientation for subsequent forming operation, correct bridge width, and the commercial roll of metal width in order to make solutions applicable in real industrial environments. Most of the procedures until now shown in literature are quite complex and often ignore these real constraints. They usually make use of sliding techniques and are not able to effectively work with relatively multiple-connected figures. In particular, most of the different proposed procedures are based on the No Fit Polygon (NFP) computation of non-convex polygons, which often generates holes. This work is a proposal for a more efficient method, which can be used in heuristic procedures. In order to overcome some faults of most of the former methods presented in literature, in this paper a new geometric entity called ??No Fit Path?? (NFPh) of non-convex polygons is applied. It allows researchers to find solutions of nesting problems even when there are NFP faults due to degenerate solutions. Moreover, the No Fit Path allows researchers to easily read, modify, or share their results, overcoming all those problems arising from the usual large amount of information and from the different origins and formats of the obtained data. Given two non-convex polygons, the algorithm is able to calculate their NFPh very quickly and without any approximation by a polygon clipping method. In this paper a totally automated procedure has been developed. This procedure firstly obtains the ??No Fit Path?? (NFPh); secondly, between all the existing positions on the NFPh, the algorithm searches the optimal one, minimizing the global waste. The proposed approach also allows designers to set an optimal orientation of the shapes on the roll of metal, taking account of the grain orientation in order to obtain the best mechanical characteristics for the cut pieces.     

Experimental investigation of the effects of short roughness strip and wall suction on the anisotropy in a turbulent boundary layer

Hot wire measurements have been made in a turbulent boundary layer subjected to a short roughness strip and concentrated suction. The suction is applied through a porous wall strip for a range of suction rate. The aim of the study is to examine the effects of short roughness strip and suction on the anisotropy of Reynolds stress tensor. The result indicates that the anisotropy of Reynolds stress tensor is increased marginally downstream of the combination of suction and roughness strip. Although, roughness strip control the magnitude of the variations of the effect of suction on the anisotropy of Reynolds stress tensor, they act independently on the mechanism of the wall turbulence of the layer. While suction acts to increase the anisotropy, roughness strip act to reduce the anisotropy.     

基于知识的级进冲模工步排样CAD技术的发展与展望

研究了基于知识的级进冲模工步排样CAD技术，分析、总结了基于模型和基于规则两种工步排样设计知识的处理方式，提出了将基于知识的工程（KBE）思想引入工步排样设计领域的方法，并建立了系统框架。     

基于POLYFLOW的汽车密封条挤出口模逆向设计研究

对某款汽车密封条挤出口模的逆向设计方法进行研究。运用POLYFLOW软件对密封条熔融体通过口模的挤出流动特性进行模拟分析,并提出了一种相对简洁的汽车密封条挤出口模逆向设计方法。模拟结果表明,密封条口模内流道熔融体挤出胀大的原因主要是由熔融体的部分弹性能得以回复和出口处熔融体速度的重分布引起。经与实际应用的口模进行比对,逆向设计出的口模横截面形状合理,可大幅度减少设计和修模时间,降低生产成本。     

截止阀特性测试与研究

根据JB／T5296－91的有关规定,对2种结构的截止阀压差－流量关系进行了测试。通过对试验数据进行双曲回归,计算出2种结构阀门在各种开度下的流阻系数,并绘制了压差－流量及流阻系数－开度关系图。