给袋式挂面包装机撑袋机构设计与分析

目的 为了避免给袋式挂面包装机装袋时的落料故障,设计筒状侧面折叠预制袋撑袋机构。方法 依据挂面充填技术要求及预制袋供送工艺路线,设计滑块摆杆撑袋机构;利用约束方程法建模,对撑袋机构进行设计;运用杆组法对撑袋机构进行运动学分析;借助Matlab编程,求解滑块摆杆撑袋机构尺度参数与运动学参数,绘制出摆杆的角位移、角速度、角加速度曲线。基于此设计加工撑袋机构,进行在线实验,并验证可靠性。结果 所设计滑块摆杆撑袋机构参数,连杆长度为89 mm,摆杆长度为115 mm,滑块偏距为122.5 mm,原动件滑块行程为10 mm,从动件摆杆摆角位移为5°;滑块位移与摆杆角位移满足线性关系,摆杆运动近似为匀加速。结论 在线实验验证该撑袋机构满足撑袋工艺要求,撑袋可靠性为94.6%,满足企业对全自动挂面包装机的要求,较好地解决了挂面包装落料故障。     

一种新型模切机间歇机构的设计与运动学

目的设计一种新型的固定凸轮连杆间歇运动机构,以实现高速模切机的间歇输纸功能。方法首先,分析间歇机构的工作原理及组合框图;然后,在对固定凸轮五杆机构的运动连续性进行研究之后,根据运动连续性条件确定间歇机构的杆长尺寸;接着,应用ADAMS软件中相对轨迹曲线生成实体的方法设计固定凸轮轮廓曲线;最后,对基于简谐运动、摆线运动和五次多项式运动的间歇机构分别进行运动学分析。结果基于五次多项式的固定凸轮连杆间歇机构不但可以实现预期的动静比,而且在高速运转下运动性能平稳。结论固定凸轮连杆间歇机构具有良好的运动性能,能够满足高速模切机的工作要求。     

青饲机青贮块间歇型自动撑袋机构的设计与优化

目的 为青饲机青贮块成型后的套袋装置中的撑袋结构设计一款基于连杆开槽的偏置曲柄滑块与双滑块组合的间歇型机构,以实现可停歇的撑袋功能,并具有急回特性,提高工作效率。方法 分析人工撑袋过程,进行撑袋机构的设计,推导该机构的停歇时间与连杆滑槽长度的数学关系式,通过Matlab优化偏置曲柄滑块的杆长参数,并利用Solidworks进行建模仿真,模拟撑袋机构的运行,对比分析3种不同行程速比系数下撑袋机构杆长参数与各自运动特点。结果 从3组数据中选取1组相对合适的参数进行公式验证,得出撑袋机构具有停歇功能和急回特性,仿真结果与解析公式计算结果一致。结论 撑袋机构设计合理,满足工艺要求,为青贮块的自动化装袋提供了可行方案。     

包装送纸机构运动学及动力学仿真分析

目的 为了提高包装送纸装置的生产效率,使用一种六杆机构应用于包装送纸装置中,并对它进行运动学及动力学仿真分析,验证它在运动过程中是否满足实际工作要求。方法 使用矢量解析法和分离体法建立该六杆机构的运动学模型和动力学模型,并采用ADAMS仿真软件对该六杆机构进行运动学仿真和动力学仿真。结果 通过对六杆机构进行运动学仿真分析,得到了输出滑块4的位移、速度和加速度曲线,该机构在水平方向的行程为680.26 mm,满足实际工况要求。通过对六杆机构进行动力学仿真分析,得到了六杆机构各铰接点的受力大小和施加在曲柄1上的平衡力矩大小,该机构在送纸行程时,各铰接点受力和平衡力矩变化较小,该机构在送纸完成后的回返行程时,各铰接点受力和平衡力矩变化较大。结论 分析仿真结果后发现该六杆机构在运动过程中满足实际工作要求,能够较好地运用于包装送纸装置中。     

基于 Creo Parametric 的包装机曲柄滑块机构的优化设计

在Creo Parametric中,通过骨架模型,创建了偏置曲柄滑块机构模型,并对曲柄滑块机构进行了运动分析,应用Creo Parametric的行为建模功能,将滑块行程、最小压力角作为约束,对曲柄与连杆的长度进行了优化设计。该方法简单、实用性强,具有很大的推广价值,为曲柄滑块机构的设计提供了新的思路。     

双曲柄多连杆压力机滑块运动曲线研究

采用杆组法,获取了双曲柄多连杆机构各铰接点处的位移方程,在ADAMS中建立了参数化仿真模型,研究了连杆长度、连杆夹角及偏心距改变时滑块位移、速度曲线的变化规律,有助于双曲柄多连杆压力机的研发.     

平装书籍打包机推书机构的优化设计

目的基于SDB-1型平装书籍打包机,以最大压力角的最小化为优化目标,对其推书机构进行优化设计。方法利用坐标轮换法和黄金分割法分别对推书机构的摆杆滑块机构和摆动从动件凸轮机构进行优化,在Matlab中求得最优解。结果优化得到了推书机构的最优杆长以及最大压力角的最小值。结论优化后的推书机构具有更好的传力性能,使得推书过程更加平稳。     

弯曲试验设备的改进

金属材料弯曲试验一般都是在万能材料试验机的弯曲试验装置上完成的,如图1、2。 现有使用的支承辊式弯曲支座总成两拉杆螺栓位置低,燕尾槽螺钉又位于支座外侧,因此承受支承辊处的水平推力条件很差,稍大一点的试样还未弯曲到180°角时,两支座的支承辊部位就向外叉开了,一次弯曲达不到图2的180°角。从目前万能材料试验机上的弯曲试验装置来看,均存在以上受力条件差的问题,虽然1000kN万能材料试验机上拉杆螺栓位置较高,大试样仍难一次直接弯曲到180°角,拉杆螺栓也有顶弯的现象。在弯曲180°角后卸荷时,需要敲打才能卸下试样。 由于现有弯曲试验设备对大多数试样不能一次直接弯曲到180°角,所以GB232—63“金属弯曲试验方法”标准中明确规定允许二次压弯到180°角,标准才能得到实施。GB232—82标准避开了二次压弯到180°角,GB232—88参照采用ISO 7438国际标准又允许二次压弯到180°角。大家都知道压弯过程的弯曲区域是自由变形,试样弯曲的内圆弧γ必然小于弯心的半径,这二次压弯到180°角除试验结果不可靠外,还使试验操纵的工作量增加一倍以上,压弯时试样容易弹出而很不安全。     

高速取纸机构设计与仿真分析

目的 利用机构实现取纸机在高速取纸时无纸间摩擦的目的。方法 明确无纸间摩擦情况下取纸吸头的姿态和动作要求。利用凸轮连杆机构的运动特点,并考虑高速运动中凸轮机构运动规律要求,设计凸轮五杆机构取纸机构。利用Adams仿真验证机构运动情况。结果 通过分析凸轮五杆机构连杆上两点的位移变化,获取作为吸头的凸轮五杆机构的连杆运动情况。通过机构的运动仿真分析可知,吸头在取纸时以垂直于纸面的姿态作间歇平动,实现了预定目标要求。结论 利用凸轮五杆机构能够很好地实现高速、无纸间摩擦取纸。     

包装机中推料机构分析及优化

根据技术要求和基本技术参数,运用解析法对糖果包装机的推糖机构进行了结构分析,运用封闭矢量法对推糖机构中的曲柄摇杆进行运动学理论计算,利用Adams 软件进行建模与仿真分析。在分析基础上运用Ad-ams 进行优化,以压力角最小为目标函数,以曲柄摇杆的长度关系和摇杆转角24. 4°为约束条件,以曲柄长度、连杆长度、摇杆长度为设计变量,得到设计变量最优解。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...