等离子弧淬火扫描螺距对摩擦磨损的影响

通过研究等离子弧淬火扫描螺距对表面摩擦磨损的影响，从摩擦学角度寻求等离子弧淬火的最佳范围，为今后淬火参数控制提供理论依据。研究表明：等离子弧淬火使被扫描表面产生了5μm左右的波度，促使相互运动表面产生油楔作用，使边界润滑向混合润滑状态转变，使摩擦系数降低，耐磨性提高；在扫描螺距为2．7时的摩擦磨损综合性能要好一些，而扫描螺距过大，并口扫描螺距小于淬火宽度时，都会使淬火表面质量下降，从而导致表面减摩性与耐磨性能降低，因此应当给予充分的考虑和合理的设计。     

数控等离子切割机弧压自动调高系统

分析等离子切割机的切割过程,并采用弧压采样的方式将采样电压经过信号处理后输入给单片机,由I/O口输出控制信号控制步进电动机,实现数控等离子切割枪自动调节高度控制.     

6J×14车轮轮辋滚压成形工艺

介绍车轮轮辋滚压成形工艺的工序设计与模具设计。该工艺与模具生产出的轮辋尺寸精度高 ,圆角减薄量小     

Estimation of springback in double-curvature forming of plates: Experimental evaluation and process modeling

This paper presents the results obtained from a series of experiments on double-curvature forming of 300 mm square and 15 mm thick plates of type 316L(N) stainless steel to evaluate the inherent springback and also to validate finite element method (FEM) based process model developed for forming of multiple-curvature sectors of large size vessels. The experimental results show that twisting of the plate occurs during pressing, which is unavoidable in an actual forming setup on the shop floor. Twisting increases with increase in slope of the die cavity. Springback in the plate changes in an ascending order towards the centerline of the plate from the edges. The final radius of curvature (ROC) on the pressed plate after springback does not remain constant along a particular axis although the die and the punch had constant ROC along that axis because of varying constraint to opening up of the plate from centerlines to the edges. Springback also increases with reduction in the stiffness of the die and punch. The simulated plate profiles obtained from the FEM process model for multiple-curvature plate forming compared well with the experiments, the maximum error being within 6%. The process model used a sequential dynamic explicit formulation for the plate pressing phase and a static implicit formulation for the unloading (springback) phase in the Lagrangian framework. Reduced integration shell elements were used for the plate and the die and the punch were considered rigid. Dynamic explicit FEM for pressing and static implicit FEM for the unloading phase are adequate and economic for modeling of plate forming process by using FEM. The necessary material and frictional property data needed for the FEM process model were generated in-house. This model can be applied to design of dies and punches for forming the petals of large pressure vessels. The FEM process model predicts the final shape of the product and the residual cold work level for a given die, punch and plate configuration and this information can be used to correct the die and punch shapes for springback to manufacture the petals to the desired accuracy.     

大圆弧弯曲件成型工艺设计方法

回弹是影响弯曲件成型尺寸的重要问题.阐述了控制弯曲件回弹的一般方法,提出了用反向回弹补偿的办法控制大圆弧弯曲件尺寸.通过模具设计解决了围板件成型回弹的技术难题,证明了这一新方法行之有效.     

一种等离子切割机切割机构的设计

针对等离子切割在不锈钢板材下料方面的应用讨论,通过对目前下料方式的优缺点分析,阐述了等离子切割在该领域应用的重大意义,设计出了一种等离子切割机的整体结构方案,详细说明了切割工艺过程。同时,对机器切割机构部分进行了深入的探讨,通过对该机构的功能和运动分析、对各种实现方案的比较以及对关键部件的设计计算,提出了一种经济适用的结构方案。该切割机构结构简单,调整方便,能较好地满足切割生产要求。     

System identification of controlled pulse keyhole plasma arc welding process

The development of closed-loop control systems is one of the most effective ways to improve the stability of the keyhole status during keyhole plasma arc welding (K-PAW). Due to the disadvantages of the one-pulse-one-keyhole technology based on the conventional square current waveform, the controlled pulse welding current waveform is newly applied to control the keyhole open and close periodically. In order to realize the real-time control on the keyhole behavior with this advanced current waveform, welding experiments and system identification are conducted based on the classical control theory. One complete welding cycle can be divided into 3 periods. The keyhole establishing time is the most important time variable, which determines the keyhole behavior and welding process stability. At the same time, the averaged efflux plasma arc voltage during one pulse cycle can reflect the real keyhole dimension and status in a real-time manner. Therefore, two single-input-single-output (SISO) systems are proposed, in which keyhole establishing time and keyhole average dimension are taken as the system controlled variables respectively. Welding experiments are designed with the peak current varying randomly. Experiments show that the keyhole establishing time changes in an opposite direction to the varied peak current, and the averaged efflux plasma arc voltage varies with the same trend as the peak current. Based on the least squares technique and F test of classical system identification, second order difference equation for keyhole establishing time/peak current system and first order difference equation for keyhole average dimension/peak current system are obtained. It is proved that the calculated data by the two mathematical expressions are well matched with the measured data. The proposed research provides mathematical expressions and theoretical analysis to develop closed-loop systems for the controlled pulse K-PAW.     

KYN28A型开关柜内部故障的电弧结构设计

开关柜内部电弧故障会引起许多效应,巨大的电弧能量将周围的空气迅速加热,引起柜内压力瞬间升高。为了操作人员和设备的安全,必须对开关柜结构进行强化设计,使其能抵御内部故障电弧能量的冲击。对此改进做了分析试验,得出了有效的结论。     

可移式管螺纹成型机减速系统方案与结构设计

为了实现可移式管螺纹成型机的预期功能，对其机械传动系统进行方案设计。在确定传动路线后，对传动比进行分配，并给出减速系统主要参数和结构图。     

旋转电弧传感器结构优化设计

针对现有旋转电弧传感器转速高、振动大的缺点,运用三维软件和ADAMS软件建立圆锥摆式高速旋转电弧传感器虚拟样机,并对传感器进行振动分析。通过增加平衡结构来减小传感器的振动,并在ADAMS中对平衡结构参数进行优化设计。优化结果表明,优化后传感器的振幅是优化前的12.9%,有效地降低了旋转电弧传感器的振动,提高了焊接成形质量。