介绍一种翻新超差冲裁模的工艺

众所周知,在设计冲裁模时,为了使冲裁件或废料不卡在凹模里,通常将凹模设计成一个出料斜度、或较短的刃口。但凸模因不受这一约束而刃口都较长。这样在相同的磨损条件下,凹模可修次数没有凸模多。往往凹模巳修磨超差,而凸模仍可继续使用。如果用某一工艺消隐凹模这些增大了的间隙,就可使凹模恢复原有的精度,冲出合格的产品。我们在超差了的凹模上方利用导料板     

逆润滑在拉深中的效用

长期以来,各种冲压理论书籍和设计手册都说拉深时,只能在凹模与工件材料接触的一面施以润滑,特别是对凹模洞口涂润滑剂,禁止在凸模上或在与凸模接触的毛坯上涂润滑剂,作者认为,这样的润滑规则不全面、欠妥当。有时候在凸模上或在与凸模接触的毛坯上涂润滑剂,反而禁止对凹模一面的工件材料特别是凹模洞口涂润滑剂,可以获得意外的效果。为了便于区分,不妨把前者称为“顺润滑”,后者称为“逆润滑”。     

低碳钢的落料(二)

3 冲模间隙间隙、冲模间隙及凸一凹模间隙都是指凸模和凹模之间空位的同义词。间隙对于冲裁设备的可靠运行、冲裁断面的质量及类型、以及凸模和凹模的使用寿命等都十分重要。一般而言间隙对落料中各因素的影响与冲孔中的影响一样。这些影响将在本卷“低     

低碳钢的落料(4)

11 常规冲模的结构与应用常规落料冲模基本上是由一对或几对配套的刚性凸模和凹模组成,是冲床生产金属板坯件的标准工具。配对的凸模与凹模的组合方式多种多样,增加附件后可以形成复合     

简化凹模形状的冲压模具设计

在保证产品质量的条件下,简化冲模结构,减少模具加工工时,从而达到降低模具成本的目的,这是冲模设计人员必须考虑的问题。实际生产中所使用的各种简易模具,有的是从简化冲模结构出发(如通用模具),有的是从取消凹模(或凸模)出发(如软模成形)。这里介绍的是简化凹模形状的成形方法,这种成形方法的特点是凹模形状不是成形后工件的形状,而是一种简化的凹模(或凸模),这就方便了模具的加工,也属一种简易的模具。此种简化凹模的成形方法及其模具结构如下:     

带凸缘薄壁喇叭形零件的整形

通过对带凸缘薄壁喇叭形零件整形工艺进行了分析,介绍了模具结构及工作过程,提出了采用浮动聚氨酯橡胶整形凹模和浮动汽缸式组合凸模,实现了对带凸缘薄壁喇叭形零件的整形,该模具对同类型零件的整形提供了参考。     

冷辗压伸缩式液压缸毛坯的工艺和设备

研究了冷辗压伸缩式液压缸毛坯的工艺和设备。确定了凹模轴线相对凸模轴线的倾角和进给量对辗压力的影响。     

锌基合金拉延成形模的结构设计和制作工艺

本文根据作者的制作工艺实践,探讨了锌合金成形模具的结构设计和制模工艺中的若干问题,并对组合式合金凸模的新制作方案以及配作凸、凹模间隙层的新材料作了介绍。     

从一实例看凸、凹模圆角半径对拉深工作的影响

本文结合实例,运用拉深变形总抗力和拉深承载能力的概念对拉深工作中的破裂问题进行了分析计算。指出了工件材料机械性能和工艺参数等因素在拉深工作中所起的作用,尤其着重讨论了凸、凹模圆角半径对拉深工作的影响,指出了拉深工作中确定凸、凹模圆角半径应遵循的工艺条件。     

支板成形模结构的改进

支板系吊风扇零件之一,原设计凸、凹模均为整体结构,给改造和修模带来较多困难,现改凸、凹模为分体结构,给改造和修模带来很大方便,修理方法大为简化,工效成倍提高,支板的几何形状和尺寸精度容易得到保证,文中分析了改进前模具的弊端,介绍了改进后模具的结构和修理方法.     

罩壳锥面侧向冲孔模

介绍了锥面上冲孔用斜楔块代替立式凸模；中JL．改善了凸模的受力状况．并提高了模具寿命。     

楔块锁紧冲头压铆模的设计

通过对组件锁柱的工艺分析,确定了冲床压铆的可行性;介绍了斜楔锁紧冲头压铆模的工作过程和特点.     

精密模锻模具设计

先从三种角度 :锻造设备和工作条件 ,钢材的加热温度和凹模结构形式对精密模锻模具进行分类 ;然后从六个方面讨论精密模锻模具设计要点模膛设计 ,凹模尺寸设计和强度计算 ,凸模尺寸和强度计算 ,模具的导向装置 ,顶出装置及飞边槽尺寸的设计     

Shear cutting and counter shear cutting of sandwich materials

New lightweight sandwich materials challenge existing forming processes as well as following process steps. As such the manufacturing potential of shear cutting has to be evaluated. Two cutting methods are compared. Method commonly used is shear-cutting within one stroke engaged, the other one is known as counter-shear cutting, which uses two strokes.The challenges of cutting sandwich materials are variation of hole diameter within the different layers, fraying of the textiles, deformation of the hole contour and burr formation. These effects occur in conventional shear cutting as the intermediate layer and the lower sheet metal are cut by the scrap of the upper sheet instead of the cutting punch.The following methodology included shear cutting with closed cutting edge i.e. cutting of holes into five different sandwich materials. The sandwiches exemplarily represent multiple kinds of possible material designs. For instance, aluminum and steel face sheets, different thicknesses of intermediate layers and different intermediate layers materials such as integrated textile fibers have been used. Adequate cutting parameters such as die clearance and the use of a blank holder have been determined. To achieve good results a stiff machine design with good guidance and precise control of punch position was crucial.Observations of conventional shear cutting revealed the need of small cutting clearance of 4%. High burnish area is possible for the upper face sheet due to the superimposed force by the lower face sheet. The major conclusion depicted that high cutting quality of sandwich materials requires counter shear cutting. Hence, the roll-over of the lower sheet facing the intermediate layer, the burnish area at the lower sheet, good cutting quality of the fibers improve significantly and burr formation is avoided completely. Summarized this paper provides cutting parameters for sandwich materials based on experimental work.     

钻头套缺口的冲裁加工

对钻头套缺口的冲裁加工进行可行性分析 ,优化设计冲模 ,并对其进行强化热处理 ,提高冲模使用寿命。     

小边距冲孔模的凹模设计

在五金、家电、办公用品等行业中,常存在一些零件需要先弯曲成形,再进行冲孔。由于结构设计要求,有些孔到弯曲边的距离尺寸较小,尺寸精度要求较高,因此在这类模具设计中,凹模的强度问题较为突出。从结构设计和工艺设计两方面给出了设计这种模具的一些心得体会。     

确定挤压凹模模孔位置的强度法

提出了以应力作为目标函数,优化模孔位置的方法,以此设计的挤压凹模,能提高其强度安全系数和使用寿命。以叉车内门架的模拟试件挤压凹模为例,进行了分析计算,结果表明,该方法简明易行。     

微型汽车车轮轮辐侧孔冲模设计

详细论述了侧孔冲模设计时模具主要参数的确定原则,说明了模具的结构和工作原理,对模具设计要点进行了简要论述,对同类零件的模具设计有一定的参考价值.     

Numerical study of the lateral crushing and re-inflation of stainless steel and aluminum tubes

The purpose of this numerical study is to investigate the possibility of re-inflating laterally crushed tubes back to their original circular-cylindrical shape, without using a die. This can find applications in a non-conventional tube bending process as well as in the repair of damaged offshore pipelines. Two materials were investigated, aluminum Al-6061-T6 and 304 stainless steel, which have very different ductility and work hardening characteristics. Three models, of increasing complexity were created and used to investigate the nature of the plastic deformation during the crushing and re-inflation, the punch load–displacement and pressure–volume responses and the geometric accuracy of the final tubes. The models demonstrated that for both materials, it is challenging to return the tubes to their original circular-cylindrical shape without using a suitable die for the crushing and re-inflation.     

LDR and hydroforming limit for deep drawing of AA5754 aluminum sheet

The goal of the research was to determine the limits and conditions in which the sheet hydroforming process provides a significant advantage over stamping in deep drawing of AA5754 aluminum sheets. Specifically, the maximum draw depth achievable by stamping, warm stamping (WF), sheet hydroforming (SHF), and sheet thermo-hydroforming (THF) of AA5754 aluminum alloy were quantified through experimental and computational modeling. A limited number of forming experiments were conducted with AA5754 aluminum sheets using a cylindrical punch and counteracting fluid at different temperatures and pressures. Several parameters, such as force–displacement, hydroforming pressure and temperature, and the maximum draw depth prior to wrinkling or tearing were measured during the forming process to make comparisons with simulations. The computational study included the simulation of stamping, WF, SHF and THF of AA5754 aluminum sheet with the LS-Dyna code, and the Barlat 2000-2d yield function with temperature-dependent coefficients. To predict the onset of wrinkling and tearing, the numerically generated, temperature-dependent forming limit diagrams (FLDs) based on the Barlat 2000-2d yield function were used. It was found that compared with stamping, SHF and THF can achieve more than 100% deeper draw depths with AA5754 aluminum sheet. The stamping simulations were used also to calculate the optimum blank size and die corner radii for the limiting draw ratio (LDR). The LDR was found to be very sensitive to the punch and die corner radii used in the experiments, which represent the curvature of character lines in an actual part. The LDR for AA5754 aluminum sheet was found to be 1.33 and 2.21 for sharp and round die corner radii, respectively. Overall, it was concluded that SHF is most ideal for deep drawing of aluminum sheets with sharp radii features. With the additional drawability provided by SHF, the automotive industry would be able to make difficult-to-form aluminum parts that cannot be stamped without product concessions such as increasing the die radii.