New plastic joining method using indentation of cold bar to hot forged part

A new plastic joining method for fixing bars with a hot forged plate is proposed in which bars kept at room temperature are directly indented into a high-temperature plate. The optimum conditions for the proposed plastic joining method are examined using a low-alloyed steel bar and a carbon steel plate. It is possible to indent the bar to the plate without buckling or plastic deformation by keeping the plate above 850 °C. The attained shear bonding stress of bar-plate is approximately 40% of the shear strength of the plate material. The bonding mechanism of the proposed plastic joining method is discussed from the viewpoints of seizure of the plate and mechanical clamping associated with the process. Furthermore, some applications of the proposed method are suggested.     

Ductility of a magnesium alloy in warm forging with controlled forming speed using a CNC servo press

The influence of press ram motion on forging performance for magnesium alloys was examined at elevated temperatures using an upsettability test on a CNC servo press. The forging limit of a wrought AZ31B (Mg–3 mass%Al–1 mass%Zn) magnesium specimen, forged using applied deceleration of the press ram motion, was found to be 30% higher than the forging limit achieved without press ram motion control. A finite element analysis was conducted to model the experimental results. The calculated temperature distribution was relatively uniform during upsetting with decelerated ram motion, and the maximum equivalent strain was maintained at a low level. Experimental and simulation results suggested that the influence of the press ram motion on the ductility of the Mg specimen could be described by a strain localization model. Furthermore, the ductility of Mg specimens during decelerated ram motion was improved in backward extrusion.     

Mechanism of mechanical press joining

Mechanical press joining has been studied for many years in the hope of achieving quality joints for dissimilar sheet metals or materials with different surfaces and thicknesses. In most of the manufacturing practices involved, the workpieces are first cut or drawn by proper punching. Then, the workpieces are clamped together by an impact extrusion between a punch and a female die. This process has been a recent resurgence in the field of permanently fastening precoated or dissimilar sheet metals, sandwich panels made of plastic and metal and pre-formed sheet metal assemblies with screws and nuts. This paper is concerned with the basic mechanism of mechanical press joining, which is useful for designing such joining elements. Some basic terms, such as the mechanical contact chains and their symbols and the joint networks, are introduced to establish a basic theory for analyzing the joining mechanism. Using joint networks consisting of the symbols of contact chains an efficient design method is presented. Some widely used mechanical press joining elements are discussed in detail in view of their mechanical behavior.     

汽车金属板件压接工艺研究

压接工艺是一种金属板件机械连接新技术。本文结合实际的工艺试验研究工作,重点介绍了压接工艺的方法,压接工艺的原理及金属流动过程,压接连接的强度特性,以及有关汽车零件的实际应用情况。     

金属板件压接数值模拟及模具设计

以有限元分析软件ANSYS为平台,基于弹塑性有限元理论建立压接模具和板件的有限元模型,对金属板件压接过程中的应力场和应变场进行计算。通过模拟结果与试验结果的比较,证实了采用ANSYS数值模拟对压接模具进行优化设计的可行性,同时研究了影响连接强度的模具设计参数。     

Laser direct joining between stainless steel and polyethylene terephthalate plastic and reliability evaluation of joints

Metals and plastics have been widely used in industrial applications, and joining of a metal to a plastic is necessary and important from a manufacturing viewpoint. Therefore, we have developed laser-assisted metal and plastic (LAMP) joining as an innovative rapid laser direct joining without adhesives or glues. In this research, the joining between a Type 304 stainless steel plate of 3 mm thickness and a polyethylene terephthalate (PET) plastic sheet of 2 mm thickness was exploited at several travelling speeds with a diode laser beam of line profile at 170 W power. The joints of 30 mm in width possessed extremely strong tensile shear loads of approximately 3000 N at the maximum. Transmission electron microscope photographs of the joints demonstrated that Type 304 and PET were bonded together on the atomic or molecular level through a Cr oxide film of stainless steel. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry analysis indicated the possibility of chemical bonding between hydrocarbon and metal through oxygen. Concerning reliability evaluation for the LAMP joints, some joints could have high shear tensile loads of approximately 3000 N even after heat cycle test and show superior air-tightness in helium leak test. Consequently, it was confirmed that the LAMP joining of SUS304 and PET plates could produce a sound joint of high strength, nanostructural binding through the oxide film and fundamental reliability for practical use.     

Cold joining of rotor shaft with flange by using plastic deformation

A plastic cold joining method of a rotor shaft with a flange was developed to produce automobiles axle parts. In this process, a high strength shaft with serrated teeth was indented into the hole of a thick disc at room temperature. The serrated shaft acts as a tool to indent to the hole. Since the disc with the teeth-shaped hole was strengthened by work hardening, the yielding strength of the join was 1.5 times as high as that of a joint produced by metal cutting. Those conditions and mechanism were experimentally determined.     

Applicability of adhesive–embossing hybrid joining process to glass-fiber-reinforced plastic and metallic thin sheets

Adhesive–embossing hybrid joining process was applied to A2017P and three types of glass-fiber-reinforced plastic (GFRP) thin sheets. Optical microscopy shows that a sound A2017P–thermosetting GFRP hybrid joint without crack/delamination in the composite or adhesive failure can be produced by optimizing adhesive thickness, embossing stroke and embossing temperature. The results of tensile shear test indicate that the optimally hybrid-bonded A2017P–GFRP joint exhibits improved load carrying capability, slip displacement and better energy absorbing characteristics than the adhesively bonded joint when subjected to tensile loading. This investigation shows that the adhesive–embossing hybrid joining process is a competitive alternative joining method for the fabrication of ultra lightweight thermosetting GFRP-metal hybrid structures and has great potential for wider applications, which is attributed to its benefits in terms of joining properties, operation simplicity, weight-cost effectiveness and recyclability.     

Experimental and numerical analysis of friction in high aspect ratio combined forward-backward extrusion with retreat and advance pulse ram motion on a servo press

A method for maintaining lubrication in the backward extrusion of deep holes for lightweight structural components is proposed utilizing a servo press and a punch with an internal channel for liquid lubricant supply. In this forming method, the punch is pushed into the specimen with a servo press in a manner that combines pulsed and stepwise modes. Sufficient liquid lubricant is periodically supplied to the deformation zone through the internal channel upon the retreat of the punch. This forming method with pulse punch ram motion was tested in combined forward-backward extrusion process with a high aspect ratio (height/diameter) in this study. The material flow of the aluminum specimen during the extrusion with pulse punch ram motion was investigated to determine the coefficient of shear friction at the specimen–punch interface. The punch wear was assessed by a finite element analysis of the material flow of the specimen during the extrusion with pulse punch ram motion.     

钨合金-钼叠层飞片的热压烧结连接

通过以Ｗ、Ｍｏ连接板材间均匀铺填Ｗ－Ｍｏ粉末中间层,并加入４Ｎｉ－３Ｃｕ烧结剂,在在实现Ｗ－Ｍｏ合金的热压烧结致密化的同时,完成了难熔金属Ｗ－Ｍｏ的低温连接（１５７３Ｋ）,并制备出平行精度高、平大幅度好、致密度高的钨合金－钼叠层飞片材料。其间详细探讨了Ｗ－Ｍｏ合金的烧结致密化机理和叠层飞片的界面连接机理。试验结果表明,由于低熔点Ｃｕ的添加,部分活性烧结剂Ｎｉ以液态形式存在,使元素Ｗ、Ｍｏ更易向Ｎｉ     

Research on nail-sheet joining by multi-plate extrusion via the three-quadrant method

In this paper, in-plane nail-sheet joints were created by multi-plate extrusion, a plastic joining method that is an alternative to traditional mechanical joining methods. Nail forming, nail cutting, nail-sheet joining and optional assembling are combined in a single press stroke in multi-plate extrusion, which can be divided into three processing periods that includes two separations. Practical experiments were performed in which compressive forces were dynamically measured at different extrusion depths. An axisymmetric model was created to simulate the process, and its results were compared with the experimental results, where both separation actions were presented. The three-quadrant method was used to estimate the exceeded length of the nail, in which an irrelevant term was required to be added to make up a four-term system which is able to create correspondence to a coordinate system with four quadrants.     

Hybrid joining process for carbon fiber reinforced thermosetting plastic and metallic thin sheets by chemical bonding and plastic deformation

A new joining process for thin metallic and continuous carbon fiber reinforced thermosetting plastic (CFRP) sheets is proposed. This joining process is a hybrid of chemical bonding and plastic deformation, usable for ultra-lightweight structures. In contrast to conventional joining methods, such as rivet joining with an adhesive, the proposed method does not require any additional components and can eliminate holes that would cut the continuous carbon fibers and cause stress concentration. Hence, a smaller weight and a higher joining quality can be attained, especially for thin sheets. Aiming at making comparison and demonstrating the applicability of the proposed hybrid joining method, two thermosetting CFRP sheets with different laminates were used as lap adherends in the experiment. The effects of the deformation temperature, the use of a dummy sheet and the relative positions of the sample and dummy sheet on the joining quality were systematically investigated and optimized. The optimal hybrid joint shows high-quality bonding without delamination or adhesive failure. The tensile shear test of single-lap A2017P-CFRP hybrid joints manufactured under optimal experimental conditions indicates that, compared with adhesive bonding and conventional rivet joining with an adhesive, the proposed joining method has obvious superiority in terms of tensile shear load, slip displacement and absorption energy.     

Effect of rotating speed on rotating tool spot joining of 5052 alloy

ABSTRACT

Rotating tool spot joining in low rotating speed range is investigated in this study. Torque of the motor increased with the decrease in rotating speed of the motor. Joint strength increased significantly with the decrease in rotating speed. Shoulder plug fracture was observed as a characteristic fracture mode under the long joining time and low rotating speed joining conditions and it obtained the large plastic deformation. The rotational motion of the joining interface was similar with the Rankin vortex. The relationship between the joining interface deformation by the external force and the plastic deformability by the friction heat on this joining process was considered from the experimental results.     

水压机活动横梁的弹塑性有限元分析

把水压机活动横梁假设成一交叉梁系,对其做了弹塑性有限元分析,导出了部分节点弯矩超过弹性极限时的梁单元刚度矩阵,讨论了计算方法的收敛性.     

112MN离合器式螺旋压力机隔振状态下的振动测试分析

对SPKA11200型离合器式螺旋压力机的隔振基础进行了振动计算与测试。结果表明,打击期间滑块的惯性力是激起压力机及其基础垂向振动的主要原因,其激振效果近似等效于对机身施加一量值等于滑块动量变化量的冲量;飞轮有及螺杆的惯性矩是激起压力机及其基础扭转振动的原因,其激振效果近似等效于对机身施加一量值等于打击期间飞轮及螺杆动量矩变化的冲量矩;机身伸缩振动很小,远小于垂向惯性力激起的振动,可予忽略。     

Determination of the elastic and plastic properties of materials through instrumented indentation with reduced sensitivity

By considering the complete loading and unloading response characteristics of multiple sharp indentations with differing indenter apex angles, a new approach has been developed to extract the elastic and plastic properties of materials. Considerable reduction in the sensitivity characteristics of all the indentation parameters invoked in the reverse analysis for the identification of the elastic and plastic properties of the indented material is realized. The reduction in sensitivity obtained using the present approach is attributed to an optimization process that identifies the material properties that best describe all the available information from multiple indentations. A comprehensive comparison of several multiple indentation methods for a large number of material combinations illustrates that the triple indentation method that does not utilize representative stresses and the quadruple indentation method that invokes representative stresses provide the least sensitivity in the determination of elastic and plastic properties.     

Prevention of galling in forming of deep hole with retreat and advance pulse ram motion on servo press

To prevent galling in backward extrusion of deep holes, an extrusion method utilizing a servo press and a punch having an internal channel for supplying liquid lubricant is proposed. On the servo press, the punch is pushed into the billet in a manner combining pulsed and stepwise modes. The lubricant is sucked into the formed hole through the internal channel during the retreat motion of the punch. Appropriate punch ram motions for preventing galling are determined from the surface observation of the formed hole. The maximum aspect ratio of the hole attained by the proposed method is discussed.     

Mechanical servo press technology for metal forming

Recently several press builders developed gap and straight-sided metal forming presses that utilise the mechanical servo-drive technology. The mechanical servo-drive press offers the flexibility of a hydraulic press (infinite slide (ram) speed and position control, availability of press force at any slide position) with the speed, accuracy and reliability of a mechanical press. Servo drive presses have capabilities to improve process conditions and productivity in metal forming. This paper reviews the servo press designs, servo-motor and the related technologies, and introduces major applications in sheet metal forming and bulk metal forming.     

Dissimilar materials joining of metal/carbon fibre reinforced plastic by resistance spot welding

ABSTRACT

Dissimilar materials joining of metal to carbon fibre reinforced plastic (CFRP), which consisted of PA6, modified polypropylene (PP) or polyphenylene sulphide (PPS) as matrix polymer with short carbon fibre, was performed using series resistance spot welding (series-RSW). The metal plate was placed on CFRP plate as the lap joint, and electrodes of series-RSW were pressed only on the metal plate side. The metal around the electrode was heated by electrical resistance heating, and the thermoplastic near the interface was slightly melted by the heat conduction from heated metal. The objectives of this research are to confirm the possibility of direct joining of CFRP and metal, and to investigate the effects of the heat input during series-RSW, silane-coupling treatment and chemical structure of matrix plastics on the joint properties.

The direct joint formations of SUS304 to CFRP (PA6) and CFRP (PP) were accomplished, and CFRP (PPS) was not. The joining area, which corresponding to the melted area of CFRP, enlarged with increasing the welding current and welding time, therefore, the tensile shear fracture load also increased. The silane-coupling treatment for metal surface was highly effective to increase the joining strength. The maximum tensile shear strength of about 13 MPa was obtained for SUS304/CFRP (PA6) joint.     

Direct dissimilar joining of aluminium alloys and polyamide 6 by friction lap joining*

Direct dissimilar joining of various Al alloy (A1050, A3004, A5052 and A5083) plates and a polyamide 6 plate was performed using friction lap joining (FLJ) with the Al alloy plate as a top and the polyamide 6 plate as a bottom. The effect of Mg content in Al alloys on the joining strength was investigated. TEM analysis made clear that the polyamide 6 and Al alloys were joined via oxide layer consisting of Al₂O₃ and MgO. The results of XPS analysis indicated that MgO was formed by the heating during FLJ, and the quantity of MgO was increased with increasing Mg content in Al alloys. The tensile shear strengths of A3004, A5052 and A5083 joints were saturated to about 2 kN because of the tensile fracture at the polyamide 6 plate outside the tool-passed zone, which were higher than that of the A1050 joint fractured at the joint interface. The peel strength of the joint was increased with increasing Mg content in Al alloys, and the fracture occurred both at the joint interface and at the polyamide 6 plate on the joint area. The fraction of polyamide 6 plate fracture was also increased with increasing Mg content in Al alloys.