垫片冲裁模的设计

分析了所要生产垫片的冲压工艺性,介绍了垫片的冲压工艺和冲裁压力的计算。根据零件本身的特点设计了一套先冲孔后落料的级进模。该模具在设计过程中,为使冲出的零件毛刺极小,断面平整光滑,采用了合理冲裁间隙,而设计部分有模具的总体设计（包括排样图设计,整体结构设计）,并附有凸、凹模主要结构参数计算和模具压力中心计算等。     

DFN产品的冲切分离技术研究

DFN产品是单面封装的产品,采用的是表面贴装技术。DFN产品封装特点使得其产品冲切分离时凸模寿命低,散热片容易产生毛刺。通过正面冲切废塑和反面冲切分离两副模具可以完成DFN产品的分离,解决凸模寿命和毛刺的问题。     

T2铜箔精密微冲孔工艺

随着微机电系统的飞速发展,微孔类零件广泛应用于生物医疗、微电子以及纺织印染等领域中,要求尺寸精度高、断面质量和重复性好,并且能够实现低成本批量制造.微冲孔技术具有传统塑性加工工艺的优点,生产效率高,工艺简单,成形件性能好和精度高,非常适合微型零件的低成本批量制造.针对箔板微孔类零件,设计了一套精密微冲孔模具,采用微冲孔技术研究了冲裁条件对微冲孔工艺的影响规律.结果表明,微冲孔过程与传统冲裁类似,经由弹性变形阶段和塑性剪切阶段,最后断裂分离.微孔断面分布仍然包括圆角、光亮带、断裂带和毛刺.随着相对冲裁间隙的增加,最大剪切强度先降低后逐渐增加;随着冲裁速度的增加,铜箔微冲孔过程最大冲裁力和最大剪切强度逐渐减小,微孔断面光亮带高度增加,断面质量提高.最后,在最佳的冲孔工艺即冲裁间隙为5%、冲裁速度为20mm/s的条件下冲出直径为0.4mm质量良好的微孔.     

双重正间隙冲裁构想与试验研究

为提高普通冲裁件断面中剪切面高度,在总结现有各种冲压分离工艺方法的基础上,提出了一种新的厚板冲裁构想,其模具结构设计为:阶梯型冲头或阶梯形凹模,且为双重正间隙.制作了原理性试验模,用材料厚度为4 mm和6 mm的纯铝板和黄铜板,分别在两台压力机上进行了冲裁试验,并与普通冲裁作比较验证.获得了冲裁件断面之剪切面高度由普通冲裁为料厚的1/3以下,提高到1/2以上的效果.并评价了该工艺及模具在生产实际中的可行性与经济性.     

铝合金板自冲铆连接过程的模拟分析

为研究铝合金板件自冲铆连接过程,借助有限元方法模拟了1.15mm AA6016T4板 1.5mm AA5182O板自冲铆接头成形.计算结果与已报道实验结果一致,证明该方法是有效的.采用此方法研究了冲头和模具的受力变化,铆扣的形成以及板件翘曲变化情况.结果表明:铆钉的变形是引起冲头载荷急剧增加的关键因素;铆钉内腔的充满压实有助于铆接压力传递到铆钉内壁,促使铆钉管腿变形形成铆合;板件的翘曲主要受压边力大小和压边圈直径影响.     

弹提高热冲模具使用寿命的方法

目的 提高热冲模具的使用寿命,降低能源消耗,提高生产效率。方法 对热冲模具使用寿命的影响因素进行分析,采取表面复合渗技术进行工艺改进,并进行工艺试验。结果 热冲模具的使用寿命由原来的每件150发提高到600发以上。结论 提高了生产效率,降低了能源、工时消耗,减轻了工人更换热冲模具的劳动强度。     

康明斯发动机推杆球座冷成形工艺及模具

介绍了一种大头短杆异形件由冷缘→车削→切断工艺到一次在二模三冲冷墩机上墩锻成形的工艺,从理论和实践上分析了墩锻成形的条件,并介绍了主要模具的设计.     

局部热处理对钢-钛自冲铆接头力学性能的影响

对钢-钛自冲铆接头进行局部热处理,并对已热处理和未热处理的接头进行拉剪实验,对比分析局部热处理对钢-钛自冲铆接头的静强度、能量吸收、失效模式和失效机理的影响。结果表明:淬火对钢-钛自冲铆接头的静强度有很大提高作用,对其能量吸收有减小作用;未淬火的钢-钛自冲铆接头失效模式为上板与铆钉分离且上板被撕裂,上板的断口形貌为典型韧性断裂特征;淬火后的钢-钛自冲铆接头失效模式为上板与铆钉分离且铆钉被拉断,铆钉的断口形貌为典型的沿晶断裂特征。     

B1500HS材料热成形后冷冲切试验

目的研究热冲压零件冷冲切刀块易磨损寿命低的问题。方法设计开发一套多功能冷冲切试验模具,对热成形后B1500HS材料进行连续冲切试验,并对3组模具间隙、4种典型模具钢材质对应的冲切试样进行断面质量检测及统计,以此分析热冲压高强钢冷冲切合理模具间隙和典型冷冲切模具钢的冷冲切特性。结果 8%~10%料厚模具间隙在冲切初期毛刺较小,且在连续冲切过程中毛刺高度比较稳定,为合理的模具间隙范围;4种典型模具钢中,ASP60冲头耐磨性性能最优,SKD11冲头耐磨损性最差,SKH-9和CALDIE介于两则之间。结论热冲压钢的冷冲切稳定性及刀块寿命相对常规高强钢还存在较大差距,针对其冲切特性有必要开发更高寿命、高性价比的模具钢及热处理方法,以提高刀块寿命和生产效率,降低零件制造成本。     

铝合金铸锻联合成形工艺毛坯冲制质量控制研究

目的提高铝合金铸锻联合成形工艺毛坯冲制良品率。方法采用优化模具设计、设备配置,增加模具保温、坯料预润滑和坯料预处理工序等综合治理方法,开展生产实验研究。结果铝合金铸锻联合成形工艺毛坯冲制良品率由原来的不足85.63%,提高到了97%的稳定水平。结论7A04铸铝坯料的冲制成形条件,比7A04挤压棒材的冲制成形条件要求高,用7A04铝合金铸造坯料代替7A04铝合金棒材冲制工件时,必须对毛坯冲制成形工艺进行细致的完善。     

金属板料可冲裁区域在线检测

在冲压零件的生产过程中,材料费用是必须考虑的问题,提高材料利用率和生产效率对降低生产成本具有重要意义。本文开创性的将冲裁工艺与机器视觉相结合,通过拍摄冲裁件图片,进行图像处理,分析出可冲裁区域,并精确排样,从而大大的提高了材料利用率和生产效率。     

橡胶注射机模具加热系统温度场模拟仿真

 热板是橡胶注射机不可缺少的模具加热元件,电热管为热板的热源,并按一定的热功率排布在热板内,使模具受热均匀．在热板的适当位置放置热电偶,用来自动控制热板温度,要求热板表面温差保持在+2~-2 ℃范围内．但一直以来,单凭人工排布形式,往往导致热板加热不均匀和温度控制精度低,直接影响热板使用性能,也是目前生产注射机企业碰到的最大难题．因此,采用有限元法,对热板进行瞬态温度场模拟仿真,得到了合理的热管排布方式,并在实际生产中证明切实可行．     

铝合金空心锥台毛坯成形工艺技术研究

针对某新型产品中的铝合金空心锥台形回转体零件在冲制成形的过程中遇到成形困难、毛坯冲制良品率低的问题进行了分析,找出了问题的原因．并根据新型空心回转体的具体特征,提出了铝管缩口、模锻成形的毛坯冲制工艺及其依据。阐述了新、老工艺各自的原理,比较了各自的优、缺点和适用性．指出新的毛坯成形工艺在冲制长径比较大的空心锥台形毛坯时所具有的优势。特别是新的毛坯成形工艺的实施不需要添置新设备,在原有设备的基础上,一次加热过程就能够实现成形目标,在保证了生产效率的同时,实现了提高冲制锥台形空心回转体毛坯良品率及进一步提高材料利用率的目标。     

Integrated and concurrent approach for compound sheet metal cutting and punching

In sheet metal processing and manufacturing, there are a lot of small- and medium-sized job shops. These small- and medium-sized manufacturing companies have been facing keen competitive pressure in the market. This pressure has forced these companies to make every effort to shorten product development lead-time, improve production efficiency, approach high-quality standards, but at the same time cut down the costs. To meet the needs of these companies, this paper presents a compound cutting and punching production method supported by an integrated CAD/CAPP/CAM system in sheet metal manufacturing. Many existing commercial CAD/CAM systems are not suitable for this manufacturing method, especially under concurrent and global design and manufacturing environments. Some problems have to be solved before these CAD/CAM systems can be employed and integrated for this compound manufacturing method. This paper deals mainly with the solutions to solve some of these problems. The solutions include an integrated data integration platform based on Pro/INTRALINK and STEP, and a knowledge-based real time CAPP (RTCAPP) system for compound sheet metal cutting and punching. Within the presented CAD/CAPP/CAM system, some key modules have been developed. They are the automatic tool selection and manufacturing sequencing module, a shortest tool path optimization module, a cost estimation module and an automatic insertion of auxiliary path module based on knowledge bases. These modules will be addressed here.     

基于钉杆变形均匀性的锥形半圆头铆钉优化设计研究

目的 针对铆接过程中铆钉钉杆发生镦粗变形,其变形的均匀性影响连接接头力学性能的问题,提出一种钉杆带有锥度的变径铆钉,以改善钉杆变形的均匀性.方法 基于三维有限元仿真方法,对准静态铆接过程进行仿真,获取锥形与常规半圆头铆钉在铆接后钉杆变形情况,同时对比分析板材残余应力变化情况.最后建立由钉杆变形均匀度与铆钉尺寸以及镦头高...     

Influence of fastener holes on residual strength

This paper derives simple formulas to predict the reduction of the residual strength due to rivet holes in stiffened and unstiffened panels of aircraft structure. Results show that the reduction can be 40 percent or more from that of panels without rivet holes. The problem is particularly severe for materials of low yield strength and high fracture toughness and for designs with small rivet spacing. It can have a serious airworthiness implication if the effect of rivet holes is unaccounted for in the assessment of aircraft structural integrity.     

Operation and Improvement of Liquid Nitrogen Pumps with Radial High- Temperature Superconductor Bearings

This paper reviews the advantages of replacing the mechanical bearings of low-temperature pumps by radial high- temperature superconductor (HTS) bearings. Radial HTS bearings have the advantage of being non-abrasive, so that the working life is increased significantly. In this article, two types of liquid nitrogen pump with radial HTS bearings are proposed. To reduce heat leakage, one pump uses a permanent magnet (PM) coupling and the other uses a long hollow pipe coupling. Successful stable operation of these two pumps means that radial HTS bearings have the potential to be applied in liquid nitrogen pumps. Test results show that the flow rate is influenced mainly by rotational speed but not by the coupling component. Further designs of the two types of pump for practical applications are described, and their characteristics are analyzed: the pump with a PM coupling has lower heat leakage, whereas the pump with a long hollow pipe coupling can solve the force creep problem of the HTS bearing. The design of the pump with a long hollow pipe coupling is based on the pump that is already in practical use, and therefore has greater feasibility for practical applications. Finally, improvements of the liquid nitrogen pump by improving the structure of the pump and the performance of the radial HTS bearing are discussed.     

Optimal process planning for a combined punch-and-laser cutting machine using ant colony optimization

A machine that performs both punching and laser-cutting operations is referred as combined punch-and-laser machine. Such a machine has been in the market for about two decades. Although process-planning tools have been used on such a combined machine, the optimization of process planning dedicated to combined machines, based on our literature search results, has never been directly studied. This work addresses the process-planning problem for the combined punch-and-laser machine by integrating knowledge, quantitative analysis, and numerical optimization approaches. The proposed methodology helps making decisions on following issues: (i) which type of operation should be applied to each feature, and (ii) what is the optimal operation sequence (tool path) to achieve the maximum manufacturing efficiency. The ant colony optimization (ACO) algorithms are employed in searching the optimal tool path. Sensitivities of control parameters of ACO are also analysed. Through applications, the proposed method can significantly improve the operation efficiency for the combined punch-and-laser machine. The method can also be easily automated and integrated with the nesting and G-code generation processes. Some issues and possible future research topics have also been discussed.     

A close neighbour algorithm for designing cellular manufacturing systems

The first step in creating a cellular manufacturing system is to identify machine groups and form part families. Clustering and data organization (CDR) algorithms (such as the bond energy algorithm) and array sorting (ARS) methods (such as the rank order clustering algorithm) have been proposed to solve the machine and part grouping problem. However, these methods do not always produce a solution matrix that has a block diagonal structure, making visual identification of machine groups and part families extremely difficult. This paper presents a ‘close neighbour algorithm’ to solve this problem. The algorithm overcomes many deficiencies of the CDR and ASM methods. The algorithm is tested against ten existing algorithms in solving test problems from the literature. Test results show that the algorithm is very reliable and efficient.