机器人搅拌摩擦点焊系统设计

搅拌摩擦点焊是一种新型固相焊接技术,机器人焊接是焊接制造业的主要发展方向,将搅拌摩擦点焊与机器人相结合,通过加工相应的焊接装置以及增加机器人的承载能力,设计完成机器人搅拌摩擦点焊装置,实现对搅拌针的精确控制。机器人搅拌摩擦点焊的控制系统是将机器人控制系统和搅拌摩擦点焊控制系统结合,在焊接过程中二者既能独立运行,又相互联系,实现搅拌摩擦点焊装置与机器人协同工作模式,从而实现无间断循环的焊接过程,提高焊接效率。通过实验对比分析机器人搅拌摩擦点焊与传统龙门式搅拌摩擦点焊焊接的工件表面成形和焊点力学性能,结果表明:机器人搅拌摩擦点焊系统实现了复杂结构工件的焊接,表面成形良好,无明显的焊接缺陷,且焊点结合强度与龙门式相当,机器人搅拌摩擦点焊系统具有良好的焊接性能。     

Evaluation of friction stir welding tool using wettability

ABSTRACT

Recently, friction stir welding (FSW) has been widely used in various fields. However, the tool wear and adhesion of the workpiece on the tool surface are serious problems. In the field of cutting tools, hard thin films were coated on the tool surface to improve the life and cutting performance of the tool. To address the problem of FSW, hard thin films such as TiN, TiAlN, TiSiN, TiBON, CrN, CrSiN and AlCrSiN were coated on the welding tools. Also, the relation between the wettability of these films and the process torque during FSW and quality of the finished surface was examined.

The wettability of pure iron and hard thin films was determined using a sessile drop method by focusing on the contact angle. The process torque during FSW was measured through the joining of low carbon steels. The process torque was significantly different depending on the type of the hard thin film. A clear correlation was observed between the wettability and the process torque. The result suggested that the tool performance for FSW can be evaluated by the wettability.     

Three-dimensional heat and material flow during friction stir welding of mild steel

Three-dimensional viscoplastic flow and heat transfer during friction stir welding of mild steel were investigated both experimentally and theoretically. The equations of conservation of mass, momentum and energy were solved in three dimensions using spatially variable thermo-physical properties and a methodology adapted from well-established previous work in fusion welding. Non-Newtonian viscosity for the metal flow was calculated considering temperature and strain rate dependent flow stress. The computed results showed significant viscoplastic flow near the tool surface, and convection was found to be the primary mechanism of heat transfer in this region. Also, the results demonstrated the strong three-dimensional nature of the transport of heat and mass, reaffirming the need for three-dimensional calculations. The streamlines of plastic flow indicated that material was transported mainly along the retreating side. The computed temperatures were in good agreement with the corresponding experimentally determined values.     

Development of friction stir welding of high strength steel sheet

Abstract

For friction stir welding (FSW) of advanced high strength steel (AHSS) sheets with tensile strength grades between 590 and 1180?N?mm^?2, the appropriate welding condition range and the influence of welding conditions on microstructures and mechanical properties of the welds were investigated. The appropriate welding conditions to avoid defects such as the incomplete consolidation at the bottom of the weld were obtained for the steel sheets up to 1180?N?mm^?2 grade. The higher tool rotation speed evidently resulted in the larger volume fraction of martensite and higher hardness in the stir zone (SZ), attributed to an increase in the peak temperature of its thermal cycle. The tensile strength of the weld joint was as high as that of the base metal for the steels up to 980?N?mm^?2 grade, but slightly lower than that of the base metal for the steel of 1180?N?mm^?2 grade due to the heat affected zone (HAZ) softening.     

高熔点材料的搅拌摩擦焊接技术

通过焊具设计、接头微观组织与性能、焊接温度场和残余应力、热源辅助的搅拌摩擦焊(FSW)几个方面,全面介绍了高熔点材料搅拌摩擦焊技术的研究现状.结果表明,合适的搅拌头材料为钨铼(W-Re)合金和多晶立方氮化硼(PCBN);采用合适的焊具设计和工艺参数,可以得到具有良好微观组织、高强度的FSW接头;在模拟搅拌摩擦焊温度场和接头残余应力时,应依据焊接过程实际进一步完善物理模型;引入辅助热源有利于高熔点材料焊缝成形并提高焊具使用寿命.     

Bobbin tool friction stir welding: a review

ABSTRACT

Friction stir welding is a solid-state welding technique for joining similar and dissimilar material. Bobbin tool friction stir welding (BTFSW) is a variant of the conventional friction stir welding process (CFSW). Compared with conventional FSW, BTFSW eliminates all limitations of CFSW using a two shoulders configuration. Now, the need has arisen to review the work done on BTFSW to provide broader aspects of the technique to researchers. This paper aims at providing comprehensive insight on the BTFSW. The paper pays critical attention to tool material selection, design features of shoulder and pin surfaces, microstructure evolution, mechanical characterisation, derivatives, and challenges in this technique. Further, welding defects and future scope of BTFSW are also addressed in this paper.     

搅拌摩擦焊应用及焊接设备简介

介绍了搅拌摩擦焊的工艺过程，分析了搅拌摩擦焊焊缝及焊接过程的优缺点。对搅拌摩擦焊的应用和常用搅拌摩擦焊设备作了简要的描述。     

T形接头角接静轴肩搅拌摩擦焊三维流动特征

在T形接头横截面方向预置0.1 mm铜箔作为示踪材料，进行了角接静轴肩搅拌摩擦焊，焊后对T形接头角焊缝进行X-ray 2D透射和X-ray 3D扫描，得到了角焊缝示踪材料的2D流场和3D流场. 在前进侧热塑性材料主要以摩擦剪切为主，材料流动主要向焊接方向流动，并流向前进侧后方，后退侧材料主要以挤压为主，由于T接搅拌针螺纹的存在，使得材料整体向后退侧下方流动. 同时发现，在T接静轴肩后沿附近下方存在示踪材料"堆积区"，表明T接静轴肩对附近的材料塑性流动存在一定的阻碍作用. 根据所获得的观察结果，建立了T形接头角焊缝的三维流动主要特征模型.     

汽车制造驶上搅拌摩擦焊之路

新世纪汽车制造轻量化的发展趋势使铝合金、镁合金等轻质合金材料所占的比重越来越大，从而促进了新型搅拌摩擦焊技术在汽车制造中的应用。在简要介绍搅拌摩擦焊技术的基础上，重点一对搅拌摩擦焊技术在汽车稠造业中的应用进行了探讨和综述，并对国内外的搅拌摩擦焊工艺装备进行了简单介绍。     

Monitoring of friction stir welding process using weld image information

Monitoring friction stir welding process based on weld images is attempted in this research. Well-known fractal theory is applied to images of the welds and extracted features in terms of fractal dimension are correlated to ultimate tensile strength (UTS) of the joints. The correlation shows a decreasing trend that can be an indicator towards monitoring of weld quality. Apart from fractal theory, wavelet transform is also applied to the acquired images and an indicator is proposed relating the information gathered after the decomposition. Interestingly, the proposed indicator also describes a decreasing trend of UTS with the increase in its value. The proposed approaches can be effectively applied in real-time monitoring of the process with appreciable accuracy.     

搅拌摩擦焊辅助装置的研究

辅助装置是搅拌摩擦焊接设备的重要组成部分,直接关系到焊接过程是否稳定进行,并对焊接质量和效率产生显著影响.论文主要介绍保护气罩、冷却回路、工装夹具和辅助热源等辅助装置.重点论述它们的作用、类型、特点及现状,为进一步扩大搅拌摩擦焊接技术的应用范围提供了参考依据.     

Themo-elasto-viscoplastic modelling of friction stir welding

Abstract

A coupled two-dimensional Eulerian thermo-elasto-viscoplastic model has been developed for modelling the friction stir welding process. First, a coupled thermo-viscoplastic analysis is performed to determine the temperature distribution in the full domain and the incompressible material flow around the spinning tool. Next, an elasto-viscoplastic analysis is performed outside the viscoplastic region to compute the residual stress. Both frictional heat and plastic deformation heat generation are considered in the model. Furthermore, this is the only known model computing residual stress accounting for plasticity caused by both thermal expansion and mechanical deformation due to material spinning. The computed residual stress is verified by comparing to experimentally measured data.     

自持式搅拌摩擦焊研究

文中综述了自持式搅拌摩擦焊的研究现状和存在的不足,主要涉及自持式搅拌摩擦焊原理、搅拌头结构、微观组织、温度场以及力学性能等几方面内容。指出了自持式搅拌摩擦焊接头的焊缝成形、温度场分布以及力学性能等特征。在此基础上提出了进一步的研究方向。     

Thermal modelling of friction stir welding

The objective of the present work is to present the basic elements of the thermal modelling of friction stir welding as well as to clarify some of the uncertainties in the literature regarding the different contributions to the heat generation. Some results from a new thermal pseudomechanical model in which the temperature-dependent yield stress of the weld material controls the heat generation are also presented.     

基于ADAMS的搅拌摩擦点焊机器人动力学仿真分析

ADAMS软件在分析机构的运动学和动力学方面有着强大的功能;针对搅拌摩擦点焊机器人的设计问题,首先建立其动力学模型,然后利用Pro/E软件建立了机器人的三维实体模型,将其导入到ADAMS中进行动力学分析,给各个关节运动副加上相应的轨迹曲线方程,使其按照指定的运动方式运动.通过仿真得到并分析了机器人各关节在运动过程中各阶段的动力学特性,为电机系统的精确选型及控制系统的设计等进一步研发搅拌摩擦点焊机器人设备提供了可靠有力的依据,对于保证其机械系统的性能以及提高其可靠性等具有十分重要的意义.     

异种材料及复合热源搅拌摩擦焊

在对接和搭接方式中,异种材料搅拌摩擦焊相较于同种材料分别具有一些额外的焊接参数,并且对搅拌头材料也有更苛刻的使用要求。总结近年来异种材料搅拌摩擦焊的研究现状,介绍异种材料搅拌摩擦焊过程中脆性金属间化合物的生成及其对焊接接头的力学性能产生的影响。从金属流动机理和数值模拟方面,研究金属间化合物的生成和成长规律,给出针对金属间化合物可能的解决方法。针对高熔点焊材,介绍复合热源搅拌摩擦焊技术、常用的辅助热源以及复合热源搅拌摩擦焊在异种材料搅拌摩擦焊方面的优点和研究的不足之处。     

Repair welding process of friction stir welding groove defect

The groove defect formed in the friction stir welding dramatically deteriorates weld appearances and mechanical properties of the joints owing to its larger size and penetration. Therefore, the friction stir repair welding was utilized to remove such a groove defect, and the focus was placed on the mechanical properties and microstructural characteristics of the repair joints so as to obtain an optimum repair welding process. The experimental results indicate that the groove defect can be removed by friction stir repair welding, and the offset repair welding process is superior to the symmetrical repair welding process. In the symmetrical repair welding process, a large number of fine cavity defects and an obvious aggregation of hard-brittle phase Al2Cu occur, accordingly the mechanical properties of the repair joint are weakened, and the fracture feature of repair joint is partially brittle and partially plastic. A good-quality repair joint can be obtained by the offset repair welding process, and the repair joint is fractured near the interface between the weld nugget zone and thermal-mechanically affected zone.     

Three-dimensional numerical and experimental investigation on friction stir welding processes of ferritic stainless steel

A three-dimensional thermomechanical simulation of friction stir welding (FSW) processes is carried out for ferritic stainless steel by utilizing an Eulerian finite volume method under the steady state condition, and the simulation result is compared directly with both the measured temperature histories during FSW and the microstructural changes after FSW. Based on a viscoplastic self-consistent approach for polycrystal, the texture development in the FSWed material is determined from the velocity gradients along the streamlines in the material flow field. The simulation results show that the heat is generated mainly near the interface between the tool and the workpiece, and that the viscosity changes drastically in the vicinity of the boundary between the stir zone and the thermomechanically affected zone. From the predicted streamlines, it can be indicated that the strong material flow mainly develops on the retreating side of the tool. Also, the simulation results show that the shear deformation texture is significantly developed in the FSWed region. The measured temperatures and microstructural characteristics agree fairly well with the predicted data.     

7022铝合金搅拌摩擦焊变形有限元分析

为了探究搅拌摩擦焊焊接变形规律,利用ANSYS有限元软件,建立了7022铝合金搅拌摩擦焊的数值模型,通过该仿真模型获得了搅拌头转速和进给速度对变形的影响.结果表明,高的搅拌头转速和低的进给速度会产生较大变形,并且搅拌头转速时变形的影响更显著.最后,通过搅拌摩擦焊试验和变形检测试验结果均表明焊件边角呈向上翘曲状态,焊板的...