基于板料网格变形的翻边工序修边线确定方法

车身零件翻边前一般有修边工序,需要准确的修边线,否则翻边后零件达不到零件尺寸要求。为减少修边模的开发周期和成本,提出一种基于板料网格变形的修边线确定方法。在零件毛坯上蚀刻上正方形网格,进行翻边前的一些工序;根据估计的修边线,得到翻边前的零件形状,测量出翻边前在修边区域上各网格点的坐标;对零件进行翻边,测量出翻边前后在修边区域上各网格点的坐标;根据翻边前后的零件网格以及翻边后零件的边缘线,通过翻边前后网格比例变形关系确定出翻边前修边线位置。如果试冲零件边缘线有误差,可反复采用这种方法优化修边线。这种方法可在模具调试或在仿真中采用。采用一个汽车地板零件的修边线确定算例,验证了上面提出的方法的可行性。     

双边剪切边质量精调控制装置探究

通过在双边剪生产工艺中增加垂直对正和导向装置,解决切边出现非长方形板材,双边切边产生弧形边、波形边、锯齿形边质量缺陷问题,实现对切边质量精调控制,提高宽、中厚板材切边质量.     

Efficacy of trimming chilled beef during fabrication to control Escherichia coli O157:H7 surrogates on subsequent subprimals

Effectiveness of trimming external carcass surfaces from subprimals during fabrication to reduce Escherichia coli O157:H7 surrogates was evaluated. Carcass sides (n = 10 sides) were inoculated along the hide pattern opening before entering the blast chill cooler with a gelatin slurry containing a bacterial cocktail of three rifampicin-resistant, nonpathogenic E. coli biotype I strains. Following a 48 h chill, sides were fabricated to produce eight subprimals. Microbiological samples were taken from the original carcass fat surface area, initial lean surface area, trimmed fat surface area (where applicable), and trimmed lean surface area (where applicable). Newly exposed lean surfaces had lower (P < 0.05) counts of rifampicin-resistant E. coli than did the external fat surfaces. However, fat and lean surfaces that were not inoculated became contaminated during the fabrication process. Trimming external surfaces reduced levels of pathogens, but under normal fabrication processes, pathogens were still spread to newly exposed surfaces.     

滚切式双边剪剪切问题分析及改进措施

针对某厚板厂剪切线投用前期双边剪使用状况,分别从剪切效率和剪切质量两方面着手,进行问题排查与原因分析,从而对现有设备进行了布置调整和结构改造,并对双边剪自动剪切程序做了改进.此外,不仅对设备的操作与维护提出了改进意见,而且对易发剪切异常现象提出了预防措施.     

轿车内饰装配质量控制技术

轿车内饰装配质量直接影响车内美观性、乘员舒适性及车体安全性 ,传统样架检验难以定量描述内饰装配偏差 ,而CMM测量数据缺乏空间直观性 ,现提出通过二维图纸或CMM测量数据反求技术建立零部件三维模型 ,利用虚拟装配技术仿真三维实体装配 ,定量装配偏差 ,控制轿车内饰装配质量 ,并以地毯总装过程中出现的地毯腾空缺陷为例 ,通过CMM测量、统计分析、反求技术及虚拟装配等技术进行地毯装配质量管理与控制     

一种用于开关电源的多模式振荡器

基于0.25 μm BCD工艺,设计了一种应用于开关电源的多模式环形振荡器,具有结构简单、三种模式可选、可修调的特点。电路通过模式切换生成可调电流的方式对电容充放电,产生不同频率的斜坡及方波信号。测试结果表明:在-40 ℃~125 ℃温度范围内,振荡器主振荡模式输出范围为483.9~518.6 kHz,与固定频率(500 kHz)的最大偏移率为3.72%,电阻频率调节模式输出范围为25 kHz~2.5 MHz,同步模式下可调同步频率范围为40 kHz~4 MHz。目前,该振荡器已被成功应用于一种DC-DC开关电源芯片中。     

Crack deviation during trimming of aluminium automotive sheets

Crack propagation and deviation during trimming of aluminium sheet metal have been analysed experimentally and modelled by a finite element analysis (FEA). The experimental results may be summarized as follows. Two crack propagation mechanisms operate in aluminium sheet metal, i.e. either between adjacent voids or by multiple coalescence of micro-cracks. A fracture process-zone may be identified for both mechanisms. Outside this fracture process-zone, no damage is observed. The particular crack propagation mechanism does not influence the crack path. A mechanical model based on a two steps analysis is presented. In the first step, the overall stress strain field prior to cracking is determined by an explicit Arbitrary Lagrangian Eulerian (ALE) formulation based FEA. In the second step, dedicated to crack propagation, no remeshing is used. A cumulative damage model based on the equivalent plastic strain increment is shown to be very efficient. The damage variable is interpreted as bifurcation in the direction of the maximum plastic strain rate. Finally, the applications show the possibility of trimming aluminium sheet metal without sliver generation.     

切边工艺对冲压件回弹影响的研究

作为冲压产品生产的重要工序之一,切边对零件形状精度产生明显影响。针对目前关于切边回弹研究比较少的情况,以某矿用防爆灯灯罩为研究对象,在Dynaform平台下,对切边回弹的产生、构成、切边线位置变化及切边工序安排对冲压件形状精度的影响进行了仿真分析,研究结果认为:切边回弹一方面是由于切边导致零件形状结构变化、内应力重新分布而引起的,另一方面是因为切边线附近应力、应变状态变化而产生的。其中前者占主导地位,在冲压加工中必须予以充分考虑,后者占总体回弹比例较小,对大型、复杂冲压件拉深成形后的切边可忽略其影响;另外,切边线位置变化、切边工序的顺序安排,对零件回弹变形影响明显,实际生产中,可通过适当选择切边线位置、合理安排切边工序在整个工艺路线中的顺序来有效控制切边回弹。     

TRIZ-based trimming for process-machine improvements: Slit-valve innovative redesign

This paper proposed a TRIZ-based integrated trimming process to resolve a process-machine problem by re-designing the problematic processing machine. Applied on a slit-valve failure of chemical vapor deposition equipment in one of major Taiwanese foundry companies, the proposed problem solving process successfully identified the critical key disadvantages of the problem and solved the slit-valve failure with breakthrough results. A number of solutions were generated by the integrated process which involves a number of TRIZ tools. This paper describes only the solution by the trimming process. Unlike the great majority of engineers use “addition” or “substitution” methods to resolve problems, the proposed trimming process used “subtraction” method to solve problem. The integrated systematic method can be used to address any process-machine related problems. The main contributions of this paper include: (1) Establishing an integrated TRIZ-based trimming process to resolve process-machine related problems capable of breakthrough problem solving and/or significant cost savings; (2) solving the slit-valve problem with 83.3% component count reduction, 95% component cost reduction, 99% operational energy reduction, and completely designed-out the original failure mode. The results have been converted into a patent pending approval.     

Friction coefficient investigation on IC dam-bar trimming process by inverse method with experimental trimmed geometric profiles

In the trimming process of integrated circuit (IC), the friction between punch and workpiece has been studied extensively. The value of the friction coefficient was usually assumed as a fixed value for the simplification of the investigations in most literature. It was seldom discussed that the values of the friction coefficient would actually increase as the trimming strokes increased. The aim of this study is to propose an inverse calculation method for the variation of the friction coefficients during the IC dam-bar trimming process. This inverse calculation is based on the geometric profiles, the profiles of the trimmed section of the IC dam-bar materials in the experimental measurement. The numerically optimized Levenberg–Marquardt method, coupled with objective functions and converge criterions along with the elastic–plastic finite element approach, is used for the inverse calculation to obtain friction coefficients during the IC dam-bar trimming process. According to the profiles of material in trimming experiment, the proposed inverse calculation was used for the number of strokes at 2000, 4000, 6000, 10,000, 12,000, and 14,000, the values of the friction coefficient were obtained as 0.1545, 0.155, 0.1613, 0.1766, 0.1875, and 0.1890, respectively. Consequently, a relationship equation between the friction coefficients and the trimming strokes can be conducted by means of the regression. The inverse calculation proposed herein can be used and obtain the values of friction coefficient with only a few experimental data and these values are more close to the actual situation during the trimming process. The results obtained in the present study could upgrade the trimming processes in the IC packaging industry.