凸轮在数控剪板机刀片间隙调整机构中应用

介绍了数控剪板机刀片间隙自动调整机构中两种不同电位器反馈刀片间隙值的方式。实验证明，凸轮和直线电位器并用的结构，能真实反馈刀片间隙，准确控制间隙精度，从而可靠地保证了剪板质量。     

刀片间隙与剪切力

剪板机多数是公用的锻压设备,无固定的操作人员。常常是使用者拿来板料之后,不是根据其厚度的需要去调节上下刀片之间的间隙,而是上去就开机剪切。结果往往造成事故,究其原因,多数是刀片间隙不合理,即刀片间隙小于应有的间隙值,     

多余物控制对电位器工作的影响

电位器在现代位置反馈式伺服系统中得到大量应用,其质量可靠性对系统的工作性能有重要的影响。电位器内部多余物的控制对电位器质量控制有重要意义,本文分析了对电位器内部多余物控制的方法和措施,对电位器的多余物控制、改进和对提高系统性能有重要帮助。     

锋利型双面槽数控刀片抛光支撑面刀尖磨损研究

通过研究锋利型双面槽数控刀片在抛光时支撑面的尖角磨损现象,分析了抛光刀片的受力并得到其运动模型,得出尖角磨损的一个重要原因是抛光刀片高频率、周期性的相对限位槽运动,设计了两种抛光夹具进行抛光测试验证,探索抛光夹具限位槽间隙、径向位置以及定位销孔间隙对刀片支撑面刀尖磨损的影响规律。实验得出：限位槽间隙对锋利型双面槽刀片支撑面刀尖磨损产生正相关的影响,而当限位槽间隙达到0.6mm后,其正相关的影响减缓;同一限位槽间隙的不同径向位置抛光时对刀尖磨损无明显影响;定位销孔间隙对刀尖磨损有明显的影响,定位销孔间隙越大,刀尖磨损越严重。本研究可指导其他锋利型产品的抛光夹具设计,抛光夹具的限位槽双边间隙设计在0.2～0.4mm为宜,定位销孔略大于支撑盘定位销即可。     

小麦联合收割机使用中的注意事项

1.作业前的准备 (1)割台部分的检查主要检查分禾器、拨禾轮有无变形或损坏,刀片是否完好无损,调整刀片间隙和压刃器间隙使其符合技术要求,确保动刀片与护刃器中线重合.     

常用玉米收获机的调整与维护

1.切割器的调整。动、定刀片前部应贴紧,如有间隙,前端不应超过0.6mm,后端不应超过1.2mm;压刃器与摩擦片的间隙不得超过0.5mm,但也不能压得过紧。如不符合规定,应通过调整压刃器、调直刀杆、加减垫片、更换刀片等方法进行解决。动刀片在行程的起或止两端位置时,动刀片与     

小麦联合收割机的故障及排除

1.刺麦秆 割刀刺麦秆是由于定、动刀片的配合间隙增大,动刀片中心线与护刃器中心线偏差太大(超过5 mm),刀片不锋利或刀片上的锯齿磨损引起的.     

钢筋切断机使用维护要点

1．使用要点(1)使用前,要检查刀片安装是否牢固,间隙是否合适,传动系统、相对运动部分的润滑情况是否良好,最后空载试运转,确认无误后方可正式开机作业。(2)固定与活动刀片的水平间隙应保持0．5～1．0mm,如果水平间隙过大则切断的钢筋端部容易产生马蹄形。两个刀片的重叠量要根据所切钢筋的直径来确定。一     

自回转车刀结构优化设计与制造

阐述自回转车刀的优点和使用中存在的一些问题。刀片回转不均匀是实际应用中面临的难题之一,解决刀片回转不均匀问题的关键在于优化设计刀片回转轴与轴承、刀片内孔之间的配合间隙。通过优化设计其结构参数以及采用合理的加工工艺,改善自回转车刀刀片的回转均匀性。通过切削试验证明,经过优化设计后的自回转车刀在实际生产中具有良好的使用性能。此外,还讨论了自回转车刀刀体与刀片制造的加工工艺问题。     

用装陶瓷刀片的端面铣刀加工灰铸铁

<正> 工业中已生产的新型氧化物——碳化物陶瓷刀片(B—3和BOK—60)具有较好的物理机械性能(抗弯强度极限分别为600和700兆帕,抗周期热力负荷性能和耐磨性能均较高),故可用于断续车削和铣削。但是,为了使用装陶瓷刀片的铣刀,刀具的制造精度和结构刚性应较高。刀片——刀体支承面和紧固件之间的连接刚度尤为重要,在连接部位不允许间隙存在,因为间隙的存在将导致在切削过程中或紧固时损坏刀片。现有结构的铣刀采用楔块和压板紧固刀片,由于制造     

Hot shearing processes: Correlation of numerical simulation with real wear phenomena

Metal sheet shearing is a necessary procedure for dimensional control during steel forming. Due to extreme operating conditions, shearing blades suffer from severe wear and need frequent repair, causing high maintenance costs. In order to increase the lifetime of cutting blades, FEM simulation of the metal shearing process was performed, implementing a hybrid friction coefficient based on data obtained from a newly developed forming tribometer. A good correlation was found between the shape of the sheared work piece as predicted by the FEM model and as found in the real application. Finally, a relationship is proposed between stress and temperature distributions as calculated by the simulation and shearing blade areas most affected by wear.     

带钢生产线液压横剪机的设计

介绍了液压横剪机的外形结构及液压控制系统工作原理，并对横剪机的剪切力、压紧力、剪刀行程、液压缸选型等参数的设计、计算作了详细分析，并通过设计实例的计算过程加以验证。     

整体涡轮大扭曲叶片电解精加工方法与试验研究

材料为高温合金的整体涡轮盘,其大扭曲叶片加工一直是制造业中的难题。提出多轴联动复合平面摆动展成电解方法加工大扭曲叶片,用一次进给电解实现叶盆、叶背面加工;分析复合平面摆动展成电解加工叶片型面成形规律,优化复合摆动展成电解加工数控编程及阴极结构设计,解决叶背出气边电解过切、根部三角区过切、出口短路等关键工艺问题;进行摆动式展成进给电解试验与分析,一次电解可达叶盆、叶背型面精加工要求。     

A sliding plate microgap rheometer for the simultaneous measurement of shear stress and first normal stress difference

A new generation of the "flexure-based microgap rheometer" (the N-FMR) has been developed which is also capable of measuring, in addition to the shear stress, the first normal stress difference of micrometer thin fluid films. This microgap rheometer with a translation system based on compound spring flexures measures the rheological properties of microliter samples of complex fluids confined in a plane couette configuration with gap distances of h = 1-400 μm up to shear rates of γ = 3000 s(-1). Feed back loop controlled precise positioning of the shearing surfaces with response times <1 ms enables to control the parallelism within 1.5 μrad and to maintain the gap distance within 20 nm. This precise gap control minimizes squeeze flow effects and allows therefore to measure the first normal stress difference N(1) of the thin film down to a micrometer gap distance, with a lower limit of N(1)/γ = 9.375×10(-11) η/h(2) that depends on the shear viscosity η and the squared inverse gap. Structural development of complex fluids in the confinement can be visualized by using a beam splitter on the shearing surface and a long working distance microscope. In summary, this new instrument allows to investigate the confinement dependent rheological and morphological evolution of micrometer thin films.     

巨型模锻液压机同步控制性能影响因素研究

同步控制系统是巨型模锻液压机上的关键部分,其同步控制性能的好坏将直接决定产品的质量。对活动横梁与导向立柱之间的配合间隙以及同步控制系统提供的工作压力与回油背压的压差对同步控制性能的影响进行了分析。结果表明:将立柱与侧梁的间隙控制在0.5mm到1.0mm之间可以满足锻件的精度要求;工作压力与回油背压的压力差越大,同步控制系统的动静态性能越好。为巨型模锻液压机同步控制系统的设计提供了参考。     

轴向间距改变对压气机clocking效应影响的数值模拟

采用一种新型的环面叶栅计算方法对两级低速压气机中径处的非定常流动情况进行了数值模拟,针对第二排静叶在一个栅距内的8个不同的时序位置下,同时移动动叶在轴向相对位置,通过数值计算结果表明:在两级静叶间轴向间距不变的情况下,动叶的轴向位置对上游静叶尾迹输运过程有显著影响,在三个CASE计算中,动叶后移时,压气机效率整体最高.轴向间距的缩短对提高整机效率有益.此外环面叶栅计算结果跟平面叶栅结果总体上趋于一致,最高、最低时序位置也相同,但流场信息更为丰富合理;相对于通常的单流道计算,环面叶栅方法更能全面反映全流道周向流动情况,从而为叶轮机械设计及前后叶排间相互干涉研究提供理论依据.     

普通冲孔与无飞边精密冲孔的瞬时间隙及对冲孔质量的影响

提出了瞬时间隙的概念 ,研究了瞬时间隙对冲孔剪口质量的影响 ,对普通冲孔工艺与精密无飞边冲孔工艺凸、凹模间的瞬时间隙进行了对比分析 ,认为普通冲孔时瞬时间隙不定常是造成剪口质量差的根本原因 ,而无飞边精密冲孔时凸、凹模间为负间隙 ,其瞬时间隙保持定常 ,因此可使剪口光洁剪切带长度提高 1.5倍 ,且冲制的孔无纵向飞边     

A model to study the reduction of turbine blade vibration using the snubbing mechanism

Blade vibration reduction is an important task in high performance turbo machinery for power generation, in order to avoid the risk of blade failure due to the overcoming of fatigue limit. A possible way to obtain this result is a contact related phenomenon, i.e. by physically limiting the vibration amplitude on the blade tip leaving a small gap between the shrouds of adjacent blades. When the relative displacement between adjacent blades exceeds the gap, in a certain vibration mode of the blade row, a contact occurs between the shrouds, the relative motion is restricted and energy is dissipated by friction and impact during the contact. This is called the snubbing mechanism.In this paper, an original simplified model of bladed disks, in which the snubbing mechanism can occur, is presented and numerical integration in time domain furnishes the time histories of the vibrations of the blades. The level of vibration reduction is then evaluated in some different modes that could be excited for instance by the fluid flow. It is also shown that unlucky combinations of system and excitation parameters can effect also a certain magnification instead of a reduction of the vibration amplitudes.Experimental results on single blade and blade groups of a steam turbine are used to tune the parameters of the system.     

Micromechanisms of deformation and fracture in shearing aluminum alloy sheet

A systematic experimental investigation is presented on trimming of aluminum alloy autobody sheets. The variations of cut surface quality and burr height are related to the cutting parameters of clearance, blade sharpness and cutting angle. It was discovered that, contrary to conventional wisdom requiring the blade to travel perpendicularly to the sheet (0°-“cutting angle”), at appropriate cutting angles the surface quality becomes insensitive to the blade sharpness, and almost zero burrs are produced for large clearances and extremely dull blades. The findings suggest that the robustness of current shearing practices for aluminum sheets can potentially be greatly improved, requiring much less frequent tool-sharpening and less restrictions on clearance control. A counter-intuitive phenomenon was revealed. At certain cutting angles and intermediate clearances, instead of burr heights and cut surface roughnesses monotonically increasing with decreases in the blade sharpness as expected, they first increased and then surprisingly decreased. Instability conditions exist at which cut surface quality and burr height are extremely sensitive to the cutting parameters.     

采煤机中间箱与行走箱对接面的科学优化

通过分析采煤机中间箱与行走箱对接面间隙的形成原因与危害,论证了有效消除该间隙的对接面改进方案,并阐述了采煤机液压螺母维护打压周期。