中厚板冲裁质量工艺研究

薄料冲裁模具,对于1.0mm以上的中厚板冲裁模具出现的冲裁质量问题——毛刺大、变形等。通常是通过增加工序来解决。为了控制中厚板的冲裁质量,通过实例分析总结出中厚板模具合理的设计参数,如模具间隙的合理选取等,作为模具设计时设计参数的选择依据,也便于后续模具制作过程的控制。     

冲裁模具磨损及使用寿命的毛刺预测法

根据板料韧性断裂的基本原理,利用DEFOM有限元分析软件对板料冲裁过程进行数值模拟,结合模具磨损规律,得出毛刺在冲裁过程中的变化规律,可以用于预测模具的使用寿命。模具在连续冲裁过程中的磨损可用不断增大的模具间隙和刃口半径来模拟,同时验证实验过程中每个阶段的实验数据,并将其导入Matlab软件进行模拟,导出模具的寿命预测模型,最后将预测结果与实验结果进行对比,验证此方法的正确性。     

聚氨酯橡胶冲裁模的应用设计

介绍了聚氨酯橡胶冲裁模的工作原理,阐述了典型零件的聚氨酯橡胶冲裁模具的设计过程,此模具能自动调整模具间隙,得到的制件平整光洁、无毛刺.     

硅钢片冲裁模具磨损计算

在Archard黏着磨损公式的基础上,通过分析硅钢片冲裁模的磨损过程和机制,提出一种硅钢片冲裁模具磨损的计算方法,并分析各参数对模具磨损和工作寿命的影响。研究表明:硅钢片冲裁模的寿命与模具允许的磨损圆角半径、硅钢片的厚度、屈强比、模具与硅钢片材料的硬度比等参数有关;硅钢片冲裁时允许的毛刺高度对模具寿命有很大的影响,在保证产品质量要求的前提下,不要过度提高对毛刺高度的要求,以避免大大增加硅钢片制造的成本。     

冲裁间隙对模具寿命的影响

在冲压加工中,模具的间隙直接关系到产品的质量和模具的寿命。通过生产实践的观察,冲裁零件上毛刺的大小,与模具刃口的钝角有关,刃口变钝与冲裁间隙有密切的关系。本文介绍模具变钝的原因及模具最隹间隙值。一、模具刃口受力分析与变钝的原因 1.模具刃口受力分析在冲裁加工中,把被冲材料分为三个区域,如图1所示。Ⅰ区域为凹模上的材料,Ⅱ区域为凸模与凹模间隙中的材料,Ⅲ区域为凸模下的材料。     

冲裁间隙的选择

间隙的选择是冲压模具设计中非常重要,亦是非常棘手的问题。间隙值是否合理,将直接影响冲裁件的质量及模具的寿命。[1] 冲裁间隙对冲裁现象的影响(1)减小间隙我们从一般的规律看冲裁间隙对冲裁现象主要有以下两方面的影响：使应力状态中拉应力减小,推迟了裂纹的产生,使断面光亮带增大,塌角、断裂面及毛刺减小,从而提高了冲裁件断面的质量。但减小间隙,会增大制模、修模的难度,且增大了冲裁力,缩短模具的寿命。(2)增大间隙使断面光亮带变窄,塌角、断裂面及毛刺增大,降低冲裁件断面的质量,且影响冲裁件的尺寸精度。但增大间隙,可…     

聚氨酯冲裁模

一般橡皮冲裁模。虽然模具结构简单、制造容易,但是冲出的零件毛刺要比一般钢制冲裁模大得多。这就加重了清理毛刺的工作量。现在我国有关工厂,采用我国制造的新型材料——聚氨酯代替橡皮,用聚氨酯冲裁模冲裁零件,冲出的零件没有毛刺。因此很受工人和技术人员的欢迎。对很薄的材料(例如板厚0.01～0.3毫米)进行冲裁,如果钢制冲裁模,则冲模要求是无间隙的。才能保证零件质量。这就使模具制造很困难,模具的寿命也较短。这时,如果使用聚氨酯冲裁模。则模具结构简单,制造容易,生产稳定可靠,产品质量满意,而且模具寿命也长。经过某厂生产试验,一块聚氨酯材料可     

冲裁件毛刺高度的确定

冲裁件的毛刺,系指剪切时在切刃边有锋利的材料凸起。而毛刺的形成主要与材料厚度、材料的抗拉强度、冲裁间隙和模具的磨损程度等因素有关。表列为西德冲压件冲裁毛刺高度标准 DIN9830所推荐的数值。当然,     

无毛刺冲件的冲制工艺

1、冲裁毛刺工艺现状目前国内外采用的冲裁工艺有两大类：一类是普通冲裁,另一类是精密冲裁,无论是哪一类冲裁工艺,所获得冲件下表面均带有纵向毛刺,毛刺的高度主要取决于被冲件材料的强度、料厚、冲裁间隙的大小和模具刃口的磨损情况等。上述因素的改善虽然可以把毛刺的高度限制到某一最小值,但不能冲制出没有毛刺的冲件,就是各种精密冲裁也不是无毛刺冲裁,虽然精冲件的剪切面光洁、尺寸精度高、形位精度高,但仍不可避免地产生比普通冲裁小的剪切毛刺,所以在通常情况下,冲裁毛刺只能进一步改善,而不能彻底清除,这些毛刺不能满…     

基于Deform应用下的冲裁模具变量对凸模应力的影响分析

冲裁模具的冲裁间隙、刃口圆角半径、冲裁速度、摩擦因数是模具设计的几个重要参数,基于Deform软件对不同间隙、刃口圆角、冲裁速度以及摩擦因数模拟出对冲压模应力的影响,并对冲压模具的应力影响参数进行正交仿真试验设计,通过正交仿真实验分析寻找规律并选出最优的组合。     

不同材料外推模型的闭挤式精冲有限元模拟比较

为了解决闭挤式精冲有限元仿真准确性的问题,基于板料拉伸试验数据,建立了5种流变应力曲线外推模型。利用Deform-2D有限元软件这一平台,植入到有限元软件的功能模块,基于开发的Deform-2D有限元软件,对直径30mm、厚度14mm圆形件的闭挤式精冲成形过程进行模拟。通过物理实验,对不同流变模型的仿真结果进行比较。研究表明,Ludwik材料外推流变模型适合于闭挤式精密冲裁工艺的有限元模拟仿真,可以有效提高闭挤式精冲有限元模拟的仿真精度。     

Prediction of burr height formation in blanking processes using neural network

Productivity and quality in sheet metal blanking processes part can be assessed by the burr height of the sheared edge after blanking. This paper combines predictive finite element approach with neural network modelling of the leading blanking parameters in order to predict the burr height of the parts for a variety of blanking conditions.Experiments on circular blanking operation has been performed to verify the validity of the proposed approach.The numerical results obtained by finite element computation including damage and fracture modelling and tool wear effects were utilized to train the developed simulation environment based on back propagation neural network modelling.A trained neural network system was used in predicting burr height of the blanked parts versus tool wear state and punch-die clearance.The comparative study between the results obtained by neural network computation and the experimental ones gives good results.     

Numerical and experimental analyses of punch wear in the blanking of copper alloy thin sheet

This research on punch wear resulting from the blanking of copper alloy thin sheet has been conducted by means of experimental and numerical analyses. Firstly, the experimental method has consisted in measuring punch worn profiles from replicas, and secondly in obtaining the wear coefficient by using a specific tribometer. The numerical modelling of blanking process has been developed with the finite element method to compute the mechanical fields necessary to calculate wear. Thus, the Archard formulation for abrasive wear has been programmed to compute the wear depth and the resulting punch geometry. Finally the simulation results of wear prediction have been compared to experimental ones.     

彩钢板成型机冲裁机构刀具动态仿真与工艺优化

优化彩钢板成型机冲裁机构刀具的冲裁工艺,减小在冲裁薄件时刀具的冲裁力,延长刀具使用寿命,提高冲裁质量.对刀具不同凹刃口的倾斜角度和上下刀具纵向的不同间隙分别进行动态有限元模拟.通过动态有限元仿真结果得出,凹刃口的倾斜角度在4～5°之间较为合适,刀具的纵向合理间隙应为板材厚度的7％左右,有利于实现减小刀具的冲裁力,延长模...     

Material characterization of blanked parts in the vicinity of the cut edge using nanoindentation technique and inverse analysis

Sheet metal blanking is widely used in various industrial applications such as automotive and electrical rotating machines. When this process is used, the designer can be faced with several problems introduced by the change of the material state in the vicinity of the cut edge. In general, blanking operations severely affect mechanical and physical properties of blanked parts. To take into account these modifications during the part design, it is important to assess the influence of the process parameters on the resulting material properties. Previous experimental and numerical investigations of blanking process have been carried out, leading to the development and the validation of a finite element model that predicts the shape of the cut edge and state of the material. The study presented in this paper makes use of nanoindentation technique to improve the validation of the previously cited model. To this end, nanoindentation tests were combined with inverse identification technique to approach some of the characteristics of material state like work hardening near its cut edges. Indentation tests were carried out in the vicinity of several parts of cut edges. Based on the corresponding load versus penetration curves, the evolution of the yielding stress resulting from the material work hardening was estimated and compared to the predictions obtained from the numerical simulation of blanking process. These comparisons show good agreement between the measurements and the predictions from finite element model.     

Finite element analysis of the thermal effect in high-speed blanking of thick sheet metal

Investigating the shear zone temperature is one of the major challenges in the study of high-speed blanking in thick sheet metals. Several studies have shown that a clear temperature change occurs even at low speed and that this significantly influences the blanked edge quality and die life; however, the thermal effects of high-speed blanking of thick sheet metals have received comparably little attention. This study proposes a methodology to predict the temperature distribution in the blanking process using a coupled thermo-mechanical finite element method for thin phosphorous bronze. The finite element model of blanking was developed to characterize the quality of the blanked edge for different punch speeds. The effect of material softening due to the heat generated during plastic work was considered in the blanking simulations. To verify the validity of the proposed model, several simulations were performed and the results, such as the blanking force and proportion of sheared area, were compared with those obtained from experimental studies. It was found that the thermal effect in thin phosphorous bronze at high punch speeds does not significantly affect the product quality. Therefore, a higher productivity can be attained while maintaining a high quality of the finished product using high-speed blanking.     

Fracture criteria identification using an inverse technique method and blanking experiment

In order to optimize the blanking processes, it is important to identify the conditions within the deforming workpiece which may lead to fracture initiation and propagation. Within this framework, numerical simulations are widely used in industries to optimize sheet metal forming processes. However, in order to have a confidence in the results of such simulations, an accurate material model is required. The accuracy of a material model is affected by the constitutive equations and the values of the material parameters. In order to reduce the danger of fracture of metal parts during manufacturing processes, advanced optimal design requires knowledge of critical values of some fracture criteria of the material used. Experimental identification of fracture criteria are currently obtained by performing several complicated tests and long duration of experiments.This study presents a computation methodology allowing for the identification of critical values of fracture criteria in order to simulate crack initiation and propagation generated by shearing mechanisms, which are needed for metal blanking processes simulation. The approach is based on inverse technique using circular blanking experiments and finite element calibration model. The critical values of fracture criteria are obtained in such a way that the finite element force–penetration predicted curve fit the experimental plot deduced from blanking tests. The numerical results obtained by the simulation were compared with experimental ones to verify the validity of the proposed technique for fracture criteria identification.     

冲裁模具间隙及凹模圆角对凸模应力应变影响的有限元分析

冲裁模具的间隙和凹模圆角,对凸模的应力、应变有重要的影响。运用有限元分析了冲裁模具在不同间隙与圆角下凸模的应力、应变特性。分析结果表明,应力、应变随着间隙和凹模圆角的增加而减小。模拟分析的结果为模具间隙和圆角半径的选择提供了依据。     

基于正交试验的半球形拉深成形工艺参数优化

以某半球形TA1钛合金拉深成形件为例,通过ABAQUS有限元软件建立了拉深成形三位模型和数值模拟正交试验方案。以是否破裂和起皱为衡量指标,探究凹凸模间隙、拉深速度和压边力对拉深成形件质量的影响,结果表明:起皱现象主要出现在压边区域不影响成形件质量,对底部最小厚度的影响从大到小依次为拉深速度、压边力以及凹凸模间隙。基于正交试验结果设计优化方案,得到最优工艺参数组合并将其应用于实际生产得到表面质量较好的拉深成形件,结果表明:基于正交试验对拉深成形工艺参数优化的方案可行,可以为企业生产提供指导,具有一定的工程应用价值。     

Numerical simulation of fine-blanking process using a mixed finite element method

In order to achieve a more intensive understanding of the forming mechanism of the fine-blanking process, a numerical simulation has been carried out by using a mixed displacement/pressure (u/p) finite element method. According to the special requirement of the fine-blanking technique, the major process attributes, such as the vee-ring, the ejector and the edge radii of tools, have been taken into account in the finite element model. The punch–die clearance was set to 0.5% of the thickness of the workpiece. To verify the effectiveness of the simulation, the equivalent strain on the sheared surface of a SS400 steel specimen has been determined experimentally. The experimental values of the equivalent strain have been estimated by measuring the relative displacements of the local grids pre-etched on the meridian plane of the specimen. The results of the finite element simulation are in proper agreement with the experimental findings. The distributions of the shear stress and the equivalent plastic strain have been computed for discussion. Moreover, a diagram of the blanking force versus the punch penetration has also been constructed. In order to investigate the fracture mechanism in the fine-blanking process, the concept of damage mechanics has been applied. By using a void growth model, the evolution of damage at different stages of the fine-blanking has been evaluated. It has been realized that the compressive hydrostatic stress built up by the fine-blanking fixture plays an important role to suppress the initiation of macrocracks.