New Quality Level of Packaging Components from Paperboard through Technology Improvement in 3D Forming

Three‐dimensional forming is a key technology for the application of sustainable materials, like paperboard, in packaging technology. Until now, deep drawing is not considered as a suitable process for manufacturing of packaging components with advanced geometrical design because of the sensitive process and a large number of failure mechanisms. To better understand and apply the physics of deep drawing, the process was studied by experimental investigations. Therefore, an evaluation strategy for formed parts was developed to describe their quality by measurable values. The influence of the technological parameters temperature configuration, moisture content of material and blank holder force on the quality of formed parts was described by a statistic regression model. This model gives an indication of the quantity and the direction of effects that parameter changes have on the quality of 3D‐formed parts. An optimization of the process according to quality criteria showed that, in a first step, the quality of cylindrically drawn paperboard parts was increased drastically compared with that of the state of the art. Furthermore, the existing limits in the height of formed parts were exceeded, and the geometrical shape of the base offered far more opportunities for packaging design than expected. The process turned out to be suitable for a flexible manufacturing of packaging components for multipart packages from paperboard, which are highly sustainable in terms of recycling and reuse of fibres and thereby able to compete in the marketing‐oriented packaging sector. Copyright © 2011 John Wiley & Sons, Ltd.     

New Methods for Quality Analysis of Deep‐Drawn Packaging Components from Paperboard

Optimization of the quality of deep‐drawn cups requires methods for precise measuring of quality criteria. This paper presents new objective methods to describe the quality of deep‐drawn packaging components made of paperboard. The state of the art for quality analysis in three‐dimensional paperboard forming is presented. Methods for the analysis of visual quality using image analysis and for the analysis of shape accuracy using surface scans are developed. Experimental results are used for the verification of the methods and for the investigation of influences of main process parameters. The new methods are found to be both precise and objective. A large blankholder force has been shown to cause an increasing number of wrinkles and has a negative influence on the shape accuracy. A high die temperature also increases the number of wrinkles but enhances the shape accuracy. The punch temperature has no effect on the number of wrinkles, but high punch temperature has a significant and positive effect on the shape accuracy. Copyright © 2014 John Wiley & Sons, Ltd.     

钛/铁复合板平底球形薄壁件充液拉深工艺研究

目的 选用充液拉深先进成形技术制备钛/铁复合板平底球形薄壁件,并研究其充液拉深变形行为,以解决传统拉深工艺制备平底球形薄壁件极易产生褶皱的问题。方法 对钛/铁复合板平底球形薄壁件在不同液压力、压边间隙及凸模与板料间摩擦因数等工艺参数下的充液拉深过程进行数值模拟。对数值模拟结果进行分析,讨论工艺参数对零件成形性能的影响以及抑制起皱的机理。最后在不同拉深工艺下进行成形试验,制备钛/铁复合板平底球形薄壁件并与数值模拟结果进行对比。结果 数值模拟和成形试验结果表明,传统拉深工艺制备的钛/铁复合板平底球形薄壁件出现了明显的褶皱,采用充液拉深工艺可以有效解决零件侧壁起皱的问题。增大液压力、减小压边间隙或增大凸模与板料间摩擦因数会导致零件减薄率的提高并降低零件侧壁起皱的风险。在压边间隙1.5 mm、液压力25 MPa的条件下,采用充液拉深工艺可以制备出侧壁无褶皱的平底球形薄壁件。结论 通过充液拉深工艺可以有效解决钛/铁复合板平底球形薄壁件成形过程中起皱的问题。     

玻璃纤维/聚丙烯复合材料层合板拉深成型性

为研究纤维增强树脂复合材料零部件快速成型,加速复合材料零部件大规模产业化量产,以玻璃纤维/聚丙烯复合材料层合板为实验对象,首先利用设计加工的拉深成型模具,进行了玻璃纤维增强热塑性树脂复合材料（Glass fiber reinforced thermoplastic resin composite,GFRTP）板材外表面纤维方向和模具长轴方向为0°和90°的试件在不同温度和不同拉深深度条件下的深拉深成型实验,将成型件制备金相试件在光学显微镜下进行微观组织观察,并对试件的成型情况和不同拉深力-行程曲线进行分析。其后进行了GFRTP板材外表面纤维方向和模具长轴方向为0°、45°和90°的试件的不同温度下的浅拉深成型实验,并对成型后的试验件进行了室温条件下的拉伸性能测试,对其拉伸失效情况及具体力学性能进行了对比分析。试验结果表明,在室温25℃到基体树脂的熔融温度165℃之间,随着温度的升高,板材的极限拉深深度增大,最大拉深力呈下降趋势。在选取的试验温度范围内,85℃时试件成型性能较好且0°试件优于90°试件,温度对拉深成型试件的皱曲改善不明显。浅拉深成型试件拉伸力学特性受试件铺层纤维方向的影响较大,防止皱曲等缺陷的发生对GFRTP板材拉深成型十分重要。     

基于RGB视觉的瓦楞包装褶皱标定收敛研究

目的 对瓦楞纸板包装的褶皱特征精确定位,保证瓦楞纸板包装容器的褶皱特征在生产中被及时检验。方法 机器视觉瓦楞纸板包装检测系统依据图像信息收集、识别算法、RGB视觉、位置标定、收敛性结果对比等部分,确定瓦楞纸板包装褶皱特征标定核心算法要点;在传统频域变换的基础上,进行RGB视觉改进算法分析,有效提高对瓦楞纸板包装的褶皱特征识别率,明确该类包装的检测要点。以实际的瓦楞纸板褶皱为例,论证该类包装褶皱特征的特征提取方法,并且强化研究对象的褶皱特征,最后对识别结果和实物结果进行对照分析。结果 通过设定阙值在90～120得到线性率为25%～80%,结果说明该视觉方式可以实现对机器视觉的瓦楞纸板包装标定,并且各特征的实际回归基准率为86%,验证了RGB视觉算法对褶皱特征标定的精确性。结论 基于该RGB视觉以及优化措施,确定了机器视觉瓦楞纸板包装标定方式,满足了瓦楞纸板包装生产的有效定位要求。     

Bending stiffness loss of paperboard at conversion — predicting the bending ability of paperboard

The ability of paperboard to resist bending has been investigated. Paperboard is often bent in converting and packaging machines. The paperboard is bent over rolls and thus formed to certain curvatures. If the roll diameter is small the paperboard will be highly curved. This means that high tensile stresses occur on the convex side and high compression stresses on the concave side. If these stresses are too high the paperboard will be damaged by fractures and wrinkles on the surfaces. The bending stiffness of the board will also be reduced. The importance of certain parameters, such as roll diameter, angle of wrap, board thickness, board compression strength and others, have been investigated. In this study seven qualities of paperboard were investigated. It has been shown that the bending force–bending angle curve can be used to obtain information about the ability of different board qualities to be bent to certain curvatures without being damaged. © 1998 John Wiley & Sons, Ltd.     

轴对称曲面零件侧壁皱纹形貌的表述及测算方法

在分析与评价几种表述皱纹形状参数的基础上，确定了适用于研究轴对称曲面类零件测壁坊皱问题的皱形参数，研制了适于测量轴对称曲面类零件侧壁皱纹形貌的测量装置，并提出了根据测量结果计算皱形参数的方法。     

Examination of the Transferability of Technological key Features of Paperboard Deep Drawing Towards the Application in Fast‐Running Packaging Machines

The deep‐drawing process of paperboard has experienced essential improvement in the recent past; however, the technological advancements have not been transferred to packaging machines yet. Two of the most important issues with regard to the reliable production of high quality 3D shapes are the use of elevated moisture and defined blank holder force profiles. This paper examines a roll preparation method for applying additional water to the paperboard and analyses a spring‐loaded blank holder solution with regard to its achieved accuracy and reliability of the force characteristics. A two‐sided roll application of water on the paperboard using a sponge rubber cover on one of the rolls produces a water intake of up to 12%. The effect of moisture applied by roll preparation is higher compared to conditioning under controlled climate conditions, and the preparation time is reduced to a few seconds. The spring‐loaded blank holder introduced in the paper completely works in position control and avoids the switch over to force control as well as the problem of small position steps, which were necessary during force control. A harmonic oscillation of the blank holder while the material is drawn out of it could not be observed up to an output of 150 cycles per minute. An application of a roll‐based moisturization unit and a spring‐loaded blank holder force in modern packaging machines appears feasible and favourable according to the results of this paper and maintains the capabilities of this 3D forming technology to a large part. Copyright © 2016 John Wiley & Sons, Ltd.     

考虑蜂窝纸板箱缓冲作用的产品包装系统跌落冲击研究*

在实际缓冲包装设计中,忽略了外包装箱的缓冲作用,因此很难得到合理的缓冲结构。为了研究外包装箱对缓冲包装系统的影响,首先基于压缩试验分别确立了制作外包装箱的蜂窝纸板与缓冲材料发泡聚乙烯的本构关系;其次建立了发泡聚乙烯与蜂窝纸板的串联力学模型,并介绍了求解算法;最后基于物品响应加速度小于许用值及材料用量最小化两个原则,设计了串联缓冲包装结构目标优化函数并介绍了优化函数的求解步骤,通过试验数据验证了模型的正确性。结果表明,如果不考虑蜂窝纸板箱的缓冲作用,会造成很大程度的保守包装,因此考虑外包装箱的缓冲作用能有效避免缓冲材料的过度使用。这些研究结果与方法为其他不同缓冲材料的串联提供了参考。     

飞机复杂曲面蒙皮零件充液拉深技术研究

目的研究充液拉深工艺参数对飞机复杂曲面蒙皮零件成形质量的影响规律。方法以飞机灯罩蒙皮零件为研究对象,结合材料力学特性分析了零件的工艺性。基于破裂和起皱失稳条件理论研究了零件的加载工艺窗口,利用有限元方法分析了零起皱和破裂等缺陷,通过优化工艺参数和拉延筋参数获得了合格的构件。结果基于仿真优化结果,进行了模具设计和工艺验证实验,分析了实际充液拉深过程中缺陷产生的原因,为落差较大蒙皮零件的精密制造提供参考。结论对于具有多特征的复杂零部件,过渡曲面易产生起皱缺陷,仅通过调整液室压力或毛料尺寸的方法无法在保证不发生拉裂和贴模问题的前提下消除起皱缺陷。通过设置拉延筋来增加材料流动阻力、控制材料流动,可以消除过渡区域的起皱缺陷。     

蜂窝纸板缓冲性能方向性的研究

通过静态压缩实验与动态压缩实验、探讨了蜂窝纸板不同方向上的缓冲性能.绘制了其不同方向上的应力-应变曲线,和最大加速度-静应力曲线.借助这些曲线,可以对蜂窝纸板在不同方向上的缓冲特点有所认识.这将有利于蜂窝纸板在包装领域的应用.     

An Experimental Study on Wrinkling Behaviours and Characteristics of Gossamer Space Structures

Abstract:  Ultra-large and ultra-lightweight gossamer space structures have received wide attention because of their small packaging volume and low cost. Wrinkle is the common deformation outcome and the main failure mode of such structures. The experimental test is essential for the wrinkling analysis, as contact test cannot be used to accurately determine wrinkling behaviour because of lightweight and flexibility. A novel non-contact dot-printing photogrammetry (DPP) based on the technology of the printed-dot targets is presented to measure wrinkling characteristics. The characteristics of wrinkle development of gossamer space structures are obtained by incorporating the DPP method and a tension wrinkling (TW) test. Results reveal that wrinkle formation is the predominant form of bifurcation when the membrane is undergoing in-plane displacement. Over-contraction deformation is the special characteristic of the wrinkles, which reflects the degree of wrinkling and region in the wrinkled membrane. The development of wrinkling can be divided into five characteristic phases, and the occurrence of the wrinkles is followed by an abrupt jump variation. DPP measurement and TW test are the effective ways to obtain accurately the wrinkling behaviours and characteristics in small-scale gossamer structures. Finite element results based on nonlinear post-wrinkling analysis are used to validate the experimental test. The numerical predictions agree well with the experimental results.     

冷链运输包装纸板的研究现状及发展趋势

目的 基于冷链物流需求日趋旺盛,对冷链运输包装纸板的研究现状进行系统分析.方法 分析冷链运输包装纸板国内外研究及应用现状,对冷链运输常用的瓦楞纸板及其结构进行阐述,同时对冷链运输包装纸板防水层和隔热层的加工工艺进行总结.结果 由植物纤维组成的包装纸和纸板,具有可再生、无毒性、成本低等显著优势,但存在使用寿命短、保温性能不佳、使用范围受限等问题亟待解决.结论 通过开发更高强度纸板原纸、赋予纸板特殊理化性能、应用多层结构纸板等方法,预期将成为纸和纸板在冷链包装中的主要发展方向.     

一种冲压皱曲缺陷的仿真分析方法

针对金属薄板冲压成形中的皱曲缺陷,提出一种基于有限元环境的冲压皱曲缺陷仿真分析方法。该方法根据工程实际应用经验将仿真环境中的冲压件皱曲进行了量化评估,通过对应变调节方向和应变调节量的分析,掌握起皱区域的成形性状态,为金属流动调节提供支持。本文以NumiSheet 2002的标准件作为应用实例,对其皱曲缺陷进行了仿真分析,结果表明该方法对皱曲缺陷分析有效、可行,可以提高金属薄板冲压成形仿真分析的效率,节约仿真成本。     

Localized Deformation in Compression and Folding of Paperboard

The localized deformation patterns developed during in‐plane compression and folding of paperboard have been studied in this work. X‐ray post‐mortem images reveal that cellulose fibres have been reoriented along localized bands in both the compression and folding tests. In folding, the paperboard typically fails on the side where the compressive stresses exists and wrinkles are formed. The in‐plane compression test is however difficult to perform because of the slender geometry of the paperboard. A common technique to determine the compression strength is to use the so‐called short‐span compression test (SCT). In the SCT, a paperboard with a free length of 0.7 mm is compressed. Another technique to measure the compression strength is the long edge test where the motion of the paperboard is constrained on the top and bottom to prevent buckling. A continuum model that previously has been proposed by the authors is further developed and utilized to predict the occurrence of the localized bands. It is shown that the in‐plane strength in compression for paperboard can be correlated to the mechanical behaviour in folding. By tuning the in‐plane yield parameters to the SCT response, it is shown that the global response in folding can be predicted. The simulations are able to predict the formation of wrinkles, and the deformation field is in agreement with the measured deformation pattern. The model predicts an unstable material response associated with localized deformation into bands in both the SCT and folding. Copyright © 2016 John Wiley & Sons, Ltd.     

Numerical and experimental analysis of wrinkling during the cup drawing of an AA5042 aluminium alloy

The recent trend to reduce the thickness of metallic sheets used in forming processes strongly increases the likelihood of the occurrence of wrinkling. Thus, in order to obtain defect-free components, the prediction of this kind of defect becomes extremely important in the tool design and selection of process parameters. In this study, the sheet metal forming process proposed as a benchmark in the Numisheet 2014 conference is selected to analyse the influence of the tool geometry on wrinkling behaviour, as well as the reliability of the developed numerical model. The side-wall wrinkling during the deep drawing process of a cylindrical cup in AA5042 aluminium alloy is investigated through finite element simulation and experimental measurements. The material plastic anisotropy is modelled with an advanced yield criterion beyond the isotropic (von Mises) material behaviour. The results show that the shape of the wrinkles predicted by the numerical model is strongly affected by the finite element mesh used in the blank discretization. The accurate modelling of the plastic anisotropy of the aluminium alloy yields numerical results that are in good agreement with the experiments, particularly the shape and location of the wrinkles. The predicted punch force evolution is strongly influenced by the friction coefficient used in the model. Moreover, the two punch geometries provide drawn cups with different wrinkle waves, mainly differing in amplitude.     

屈曲薄膜振动分析

非线性大变形屈曲分析是处理薄膜褶皱问题的一种有效方法,该文对这种方法的两个关键问题进行了探讨,包括初始缺陷的施加及后屈曲平衡路径的跟踪。基于这种方法分析了剪切薄膜的褶皱,并在褶皱构形的基础上,进行了考虑大变形效应的模态分析。分析结果表明:具有褶皱薄膜振动的模态及固有频率与不具有褶皱的薄膜相比明显的不同,褶皱薄膜的固有频率明显的减小了,其节线的位置为张拉线的位置,随着模态的增加其节线的数目减少。该文所建立的分析过程,不但能够进行薄膜褶皱的分析,同时也能分析褶皱形成后薄膜的动态特性。     

响应面分析法在油墨耐光色牢度测定中的应用

目的筛选出包装纸板在试验箱中开展耐光色牢度试验的5个影响因素值,并验证方法的稳定性。方法用配备了滤光器氙弧灯的试验箱模拟日光中紫外区域的光谱能量分布,调整曝晒条件模拟包装纸板及制品日常使用环境,通过响应面分析法对曝晒因素进行分析,并采用色差计量化评定试样印刷油墨的色差值耐光色牢度。结果优化的试验箱曝晒条件,黑板温度为(65±1.0)℃,空气温度为(45±1.0)℃,空气相对湿度为(50.0±2.0)%,光辐照波长为340 nm,光辐照度为0.30 W/m²,光辐照时间为42 h。通过色差计测定人工曝晒后样品印刷油墨色差ΔE^*_ab。结论验证试验表明,该方法测试结果具有可靠性及稳定性,为进一步规范包装纸板及其制品产品质量监管提供分析测试技术支撑。