Study of the punch–die clearance influence on the sheared edge quality of thick sheets

Sheet metal punching is an important industrial process for forming mechanical parts. Aimed at generating holes on thick sheets, punching process has been considered as a promising solution for the heavy industrial sector. The correct punching parameters choice has a direct influence on the hole quality. Since there exists rarely an analytical expression describing the relationships between these process parameters, the forming variable choice follows a series of costly try-and-error procedures on the workshop floor. The numerical simulation is a powerful tool that helps the forming engineers at the try-and-error procedures. This work shows the possibility of using FE-simulations to reduce the number of experiments that has to be conducted propitiating an increased understanding concerning some punching process parameters influence. The aim is the study of the clearance influence on the punched holes quality, 8 mm LNE38 sheet metal. Clearances of 0.2% up to 15% between the punch and die were analyzed. The influence of the punch–die clearance on the crack propagation was also analyzed, and the results were in agreement with the literature, i.e., good results for gaps within the traditional ideal range and occurrence of burr for clearance of 15%.     

圆盘剪分切工艺有限元仿真研究

基于金属板材圆盘剪分切工艺,应用DEFORM-2D仿真软件建立了金属板材的圆盘剪分切模型,采用Oyane韧性断裂准则仿真研究了304不锈钢板材圆盘剪分切加工过程,探讨了圆盘刀轴向间隙、刃角半径、压板力、板厚等工艺参数对分切断面形貌特征的影响规律。轴向间隙是影响分切断面形貌特征的主要因素,随着轴向间隙的增大,塌角高度增大,剪切带高度减小。刃角半径对断面的塌角高度、剪切带高度影响不大,对毛刺高度影响最大,随着刃角半径增大,毛刺高度增大。压板力对断面的塌角高度、剪切带高度影响很小,对毛刺影响较大,随着压板力增大,毛刺高度有下降趋势。板厚对分切断面塌角和毛刺影响不大,对剪切带高度影响很大,随着板厚的增大,剪切带高度增大。     

ANSYS在小孔冲模间隙优化中的应用

运用软件ANSYS的弹塑性有限元理论,重点研究了冲压模间隙对板材成形性能的影响,观察分析应力、应变分布和变形网格情况并与实践对比,模拟分析结果与生产实践基本吻合.板材成形有限元法为快速有效地确定冲压模间隙,优化模具设计,降低模具设计成本和缩短模具设计周期提供了一种可实施的手段.     

A new sheet metal forming system based on incremental punching, part 2: machine building and experiment results

The paper is the second of the two papers on a new sheet metal forming system of incremental punching. In the first paper, the mechanics model is introduced, and the computer simulations are carried out. This paper consists of two parts: the design and building of an incremental punching machine and experiment results. The machine is a three-axis computer numerical controlled (CNC) machine with a high-speed hydraulic punching head. Given a part, the punch path can be generated using commercial CAM systems with some modifications. Then, the machine takes over forming the part punch by punch. The formability of this system is also investigated giving the maximum forming angle. Following the first paper, two examples are studied in details. The experiment results indicate that the new system is effective for sheet metal rapid prototyping. Finally, some future research topics are discussed.     

精密无飞边冲孔瞬时间隙及塑性状态研究

研究了精密无飞边冲孔的瞬时间隙和冲孔变形区的材料塑性状态判定参数，提出一种瞬时间隙恒定的精密无飞边冲孔工艺，确定了弹性变形比能的最大值，讨论了瞬时间隙和塑性状态判定参数对冲孔质量的影响，为工程应用和新工艺的研究提供了参考依据。     

基于CNCKAD的钣金件制造技术

为实现钣金件的数字化制造,提出了钣金的数控冲压加工,研究了基于CNCKAD软件的数控程序编制问题。首先,选择典型的数控冲压设备,编制冲压加工工艺;然后,建立制造数学模型,定义编程操作,生成数控机床用的加工程序;最后,通过实例仿真加工,验证了所述方法的可行性和正确性。     

Pro/E软件实现90°角钣金件1∶1展开的二次开发及应用

目前在钣金企业中,钣金件展开图绘制的效率较低,且易出错误。本文通过分析90°角钣金件展开长度的计算方法,对Pro/E软件自带的折弯表进行二次开发。对于前期90°角钣金件的Pro/E模型,通过加载二次开发折弯表,可以实现1∶1准确展开;对于新建90°角钣金件的Pro/E模型,可通过对钣金件公制、英制模板文件设置后,直接按照1∶1准确展开,展开后工程图可以保存为DXF文件,可以直接输入到数控塔冲和数控激光切割机中进行编程加工。二次开发折弯表仅适用于90°角钣金件。     

金属切削毛刺专家系统的研究进展

毛刺是金属切削加工中产生的常见现象之一,它的尺寸和形状直接影响到工件的尺寸精度和形位精度,甚至影响到工件的使用性能及其寿命.随着机械制造业朝着高精度,高效率和自动化方向发展,对切削加工精度的要求越来越高.由于专家系统具有数据结构化,数据和应用程序的高度独立性、数据共享,并将数据冗余减少到最小限度等优点,在金属切削毛刺形成研究与控制上逐步得到了越来越广泛的应用,对加工精度起到了很好的效果.在分析现有毛刺研究成果的基础上,与专家系统进行了对比与分析,体现出了专家系统在毛刺研究领域应用具有的优点,并阐述了现有的金属切削毛刺专家系统的研究现状,指出了尚存在的一些问题,从而为今后毛刺专家系统的发展提供借鉴.     

The path to lean success - WHEN A SPANISH MANUFACTURER UPGRADED ITS PRODUCTION EQUIPMENT IT TOOK THE OPPORTUNITY TO TAKE THE FIRST STEPS ON A LEAN JOURNEY

Spanish manufacturer of industrial electrical appliances, Fagor Industrial, redesigned its production system to enable lean flows by means of waste reduction. Using the value stream mapping (VSM) technique to analyze and plan the improvement project, Fagor decided to make technological changes to its sheet metal cutting line. The seven Trumpf punching machines were replaced with four new laser technology machines, in addition to the acquisition of the latest generation software. This allowed Fagor to create multi-part programs, guaranteeing good use of sheet metal, which also gives the advantage of working with unitary batches of parts adjusting the production to the demand. This also provided the opportunity of working in kanban supply system, owing to the reduction of format changes in the machines. Furthermore, there is freedom in the design process as the dependency between the set of punches and the geometry of the part is eliminated     

CIMT2003锻压机械展品评述

第八届中国国际机床展览会锻压机械类参展商约80家,国内参展商(包括台湾地区和外企的代理商)约54家,国外参展商约26家。共展出锻压机械类展品110余台套,其中国内展品约80多台套,国外展品约20多台套。与上届展览会比较,国外参展商数量略有增加,而展品数量有所减少。     

普通冲孔与无飞边精密冲孔的瞬时间隙及对冲孔质量的影响

提出了瞬时间隙的概念 ,研究了瞬时间隙对冲孔剪口质量的影响 ,对普通冲孔工艺与精密无飞边冲孔工艺凸、凹模间的瞬时间隙进行了对比分析 ,认为普通冲孔时瞬时间隙不定常是造成剪口质量差的根本原因 ,而无飞边精密冲孔时凸、凹模间为负间隙 ,其瞬时间隙保持定常 ,因此可使剪口光洁剪切带长度提高 1.5倍 ,且冲制的孔无纵向飞边     

基于单片机的数控冲压进给系统的设计

金属板材加工是金属加工的一个重要门类,为了改变冲压生产率低,效益差的状况,本文以开发经济、实用的高速数控冲压进给系统为目标,从机械与控制两个方面对冲压进给系统展开设计.设计中提供了数控冲压进给系统的各组件选型方法及其最终结构设计参数,为普通冲床的数控改造提供了理论依据,同时对于数控冲压系统的完善起到积极的促进作用.     

金属切削毛刺专家知识系统的开发

毛刺是金属切削加工中产生的常见现象。研究开发出了金属切削毛刺专家知识系统，为管理切削实验所测的毛刺数据、查询毛刺类型与尺寸、优化选择加工参数和进行切削毛刺形成的动力学仿真等奠定了基础。进而，为实现切削毛刺的预报与控制开辟了新途径。     

钴始极片数值模拟成形参数的优化

电解金属钴的始极片板面尺寸较大,厚度薄,韧性差,为防止在储存和运输过程中发生变形或断裂,需要对钴板进行压筋处理,以提高其强度和刚度。采用薄板成形研究软件DYNAFORM对其进行冲压仿真分析,运用正交优化的原理找出合理的零件结构参数和成形工艺参数来指导钴始极片的生产。     

Modular tool concept and process design for micro impact extrusion

Micro impact extrusion is an appropriate mass production technology for micro structuring of sheet metal. The technology was applied to form sample geometries consisting of ten precision cavities which are intended to be collets for the form- and force-locked integration of piezo rods for later usage of the sheets as “smart sheet metal”. For reasons of flexibility, a modular tool concept was studied and applied. It allows a flexible arrangement of geometry elements but introduces new aspects which need to be considered. This study investigated the influences of tribological- and process parameters onto the microforming process. Therefore forming experiments were performed with different die coatings (titanium nitride, titanium carbon nitride, amorphous carbon), different lubricants (common oil, forming lubricant and without lubrication), as well as two die materials. In contrast to forming processes with established monolithic die configurations, phenomena like tilted structures and the appearance of unwanted burr were investigated. For creating structures with minimal tolerances, these effects need to be considered. The investigation of the influence of process parameters showed, that the lowest surface roughness was achieved without lubrication. Furthermore low-friction coatings and harder die materials improved the forming results.     

Experimental analysis of sheet metal micro-bending using a nanosecond-pulsed laser

Laser shock bending is a sheet metal micro-forming process using shock waves induced by a nanosecond-pulsed laser. It is developed to accurately bend, shape, precision align, or repair micro-components with bending angles less than 10°. Negative bending angle (away from laser beam) can be achieved with the high-energy pulsed laser, despite the conventional positive laser bending mechanism. In this research, various experimental and numerical studies on aluminum sheets are conducted to investigate the different deformation mechanism, positive or negative. The experiments are conducted with the sheet thickness varying from 0.25 to 1.75 mm and laser pulse energy of 0.2 to 0.5 J. A critical thickness threshold of 0.7-0.88 mm is found that the transition of positive–negative bending mechanism occurs. A statistic regression analysis is developed to determine the bending angle as a function of laser process parameters for positive bending cases.     

敏捷冲裁模具系统设计中的图形处理技术

介绍了敏捷冲裁模具系统的组成模块及其功能结构．详细阐述了其中图形处理模块的数控编程技术的开发方法,通过分析数据交换文件(DXF)图形文件结构,提取数控加工所需的数据信息,再根据现场加工工艺要求,对这些图形数据作进一步处理,然后自动生成机床加工的数控代码格式．同时,该系统模块具有加工动态仿真和NC代码检验功能,从而提高了加工效率和加工质量．     

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。     

板料自动冲裁系统的研制

针对企业的实际需求,设计了一套板料的自动冲裁系统。该系统以辊道压板机构实现板料的自动送料,以皮带输送机构、气动装置等实现冲裁件或废料的自动输送及分离,以西门子S7-200 PLC和传感器、计算机等实现整个冲裁过程的自动控制,实现了板料的自动化冲裁。在江苏金秆农业装备有限公司的成功运行,表明本系统满足了安全、优质、高效、稳定等方面的要求。