Investigation of the coating thickness of plasma-transferred arc deposition welded and cross wedge rolled hybrid parts

Most of today’s technical parts and components are made of monolithic materials. These mono-material components produced in established production processes reach their limits due to their respective material characteristics. Thus, a significant increase in production quality and efficiency can only be achieved by combining different materials in one part. Bulk forming of previously joined semi-finished products to net shape hybrid components that consist of two different materials is a promising method to produce parts with locally optimized characteristics. This new production process chain offers a number of advantages compared to conventional manufacturing technologies. Examples are the production of specific load-adapted forged parts with a high level of material utilization, an improvement of the joining zone caused by the following forming process and an easy to implement joining process due to the simple geometries of the semi-finished products. This paper describes the production process of hybrid steel parts, produced by combining a plasma-transferred arc deposition welding process with a subsequent cross wedge rolling process. This innovative process chain enables the production of hybrid parts. To evaluate the developed process chain, coating thickness of the billet is analysed before and after cross wedge rolling. It could be shown, that the forming process leads to an improvement of the coating, meaning a more homogeneous distribution along the main axis.     

Influence of different alloying elements on the intermetallic phase seam thickness of compound forged steel-aluminum parts

In times of increasing energy costs automotive light weight construction is gaining more importance. Thus, attempts have been made to replace steel components with parts made of aluminum alloys. This, however, often involves the deterioration of important component properties and impedes material substitution in mechanically high-stressed parts like gear components. Due to this, the attempt to design load-optimized parts with hybrid structure which correspond to the requirements of structural light weight construction is made. The production of hybrid compounds by forging is a promising method to manufacture functional parts by applying resource-saving process steps. The aim of the presented research is to determine the optimal production parameters for compound forging. To characterize the component quality it is necessary to investigate the factors influencing the joining zone.     

Effect of the primary heat treatment on the bond formation in cold welding of aluminum and steel by cold forging

Cold forging enables the manufacturing of high strength monolithic components. When used as joining technology it can also be extended to an enabler of multi-material product design. The contact conditions at the interface between the components during the cold forging process play a crucial role. The joining of two billets of steel and aluminum is investigated by a finite element analysis with regard to the material distribution and the effect of a primary heat treatment of both materials. These parameters affect the surface enlargement and the contact normal stress which are decisive parameters for the formation of a sound bond between aluminum and the hardly cold weldable steel. The experimental results present the effect of a primary heat treatment on the bond formation. Microscopic analyses of the bond formation allow a deeper insight into the bonding mechanism. Thus, the results lead to process design guidelines for cold welding by cold forging.     

A review on tailored blanks—Production,applications and evaluation

Tailored Blanks is the collective for semi-finished sheet products which are characterised by a local variation of the sheet thickness, sheet material, coating or material properties. With these adaptions the tailored blanks are optimised for a subsequent forming process or the final application. In principle four different approaches can be distinguished to realise tailored blanks: joining materials with different grade, thickness or coating by a welding process (tailor welded blanks), locally reinforcing the blank by adding a second blank (Patchwork blanks), creating a continuous variation of the sheet thickness via a rolling process (tailor rolled blanks) and adapting the material properties by a local heat treatment (tailor heat treated blanks). The major advantage of products made from tailored blanks in comparison to conventional products is a weight reduction. This paper covers the state of the art in scientific research concerning tailored blanks. The review presents the potentials of the technology and chances for further scientific investigations.     

Process Stability in the Tube Hydroforming Process

Material properties have a significant influence on the process stability in tube hydroforming, particularly in series production. Mainly tubular material with longitudinally oriented welding lines is used in tube hydroforming. A new test method was developed to examine the important properties of the semi-finished product, such as flow pressure or maximum circumferential elongation during the hydroforming process. Knowing these parameters, the process control can be adjusted according to the differences of the varying semi-finished product charges. Another option to improve the process stability is a new process control strategy, which uses the volume flow instead of the conventionally used pressure as control variable. A volume control enables the production of sound parts made of different materials with varying wall thicknesses without changing the process control settings.     

Special features of the process of automatic argon-arc welding of steels with an aluminium coating

Over the last few years, worldwide aluminium consumption has been constantly on the rise. Certainly the most important driving force in this development is the need for lightweight and fuel-efficient design in all fields of transportation. Consequently, the importance of successful and profitable processing of aluminium into serviceable products or components comes more and more into the focus of manufacturing industry. Unfortunately, this necessity is complicated by some of aluminium's material properties because they differ significantly from steel's properties, with which in most cases manufacturing experience has been gained; and by the fact that for an optimum lightweight design, a material mix of different alloys and semi-finished products (extrusion, forged, rolled, or cast parts) is necessary, creating a vast variety of different possible surface and material conditions. In terms of joining processes for aluminium, gas shielded arc welding is outstanding. But the above-mentioned material diversity, in combination with mass production requirements, results in a comparably small operating window for successful welding. This results in a significant reduction in profitability due to, for example reduced welding speed, excessive downtime of the production line, scraping, or reworking after welding. To explain how counteracting aluminium-related welding defects is possible by means of the shielding gas used, this paper will take a close look at the properties of different shielding gases: the column of the electric arc, the aluminium surface (oxide film), and surface transactions. It will also explain how a dose of active O₂ in an inert shielding gas will contribute to an enlargement of the welding operating window, and, as such, how the choice of shielding gas can increase the profitability of the welding process.     

Material adapted tool design in cold forging exemplified by powder metallurgical tool steels and industrial ceramics

The advantages of today’s cold forging technology, such as excellent mechanical properties of the workpiece and minimum waste of material together with energy saving via near net shaping increase its competitiveness against other production methods. However, as a result of extremely high loading of the tools when compared with warm and hot forging, tool life is distinctly more confined resulting in increased production costs. Due to separately or concurrently emerging damaging mechanisms of fatigue and wear at different sections of a cold forging die, process specific tool material selection and design of cold forging dies play a decisive role in near-net-shape forging of various parts. Two case studies utilizing powder metallurgical tool steel and ceramic as tool materials are presented in this paper. Successful adaptation of these materials with the help of FE simulations led to increased tool life and workpiece quality.     

压力机PBOM的生成及其管理技术

物料生产清单(BOM)也叫产品结构或配方,是MRP系统中最重要的概念之一。物料(通常是完成品或半成品、部品)的组成:由哪些下级物料组成,每一下级物料的用量是多少,包括其对应的属性等。工艺物料清单(PBOM)在工艺设计和生产制造中具有承上启下的重要作用。文章结合压力机制造业的特点,分析了物料编码的基本原则、物料编码方法、压力机PBOM的生成、PBOM的多级展开、PBOM的多级反查、PBOM的更改管理和有效控制。     

New cross-rolling process for joining of hybrid components

The proposed innovative cross-rolling process can be used to form hybrid components like shaft hub connections and electric drive parts. The advantages as well as the challenges are discussed in detail, especially the resulting notch geometry and possible approaches for mitigating adverse effects. While the shaft ideally should be a high strength steel, generally any other metal, ceramic or composite material can be used as a joining partner. This paper will present a numerical analysis of the joining process regarding work roll path and geometry as well as an experimental evaluation of the achievable properties and the resulting transmissible loads.     

Joining by forming—A review on joint mechanisms,applications and future trends

Public demand for an efficient and sustainable use of energy and resources has led to new design criteria for technical products. An even more consequent use of light-weight construction and so-called smart structures are two examples of this. Both approaches lead to hybrid components consisting of dissimilar materials. Joining processes based on plastic deformation of at least one joining partner promise great potential regarding the production of multi material joints. This paper first examines in detail the basic plastic joining principles for force- and form-closed joints as well as for solid state welds and presents a systematic classification. Subsequently, the joining processes based on these principles are discussed along with their specific potentials and limitations. Additionally, industrial applications of these processes are presented. Future trends in joining by forming based upon current research developments are finally highlighted. Despite these extensive research activities the outlook shows that gaps of knowledge still exist and hinder a broad industrial application so far.     

欧洲管材内高压成形和板材液压成形研究现状(英文)

在欧洲,管材、型材以及板材的液压成形是密切相关的。液压成形产品主要是用于汽车工业批量生产的零件以及一些有独特用途的零件,其市场仍然在逐渐增长。目前轻量化制造、新型零件的高度功能集成化以及关于使用内高压件的不断积累的设计经验、理念,正影响着液压成形新技术的开发。由于可观的利润率,开放截面和闭合截面的铝合金型材的液压成形件正在试制,并在此背景下,开展了一些专用车面板的液压成形技术开发。这个利润率,将从半成品零件、成形中间过程,直到最终总成件整个工艺链来计算。从管材和板材的液压成形件来看,提高液压成形模具的功能集成性也是必须要做的工作。文章作者就内高压成形的模具设计以及功能集成给出了解决方案,并进一步讨论了内高压成形工艺的利润率。     

Analysis and specification of the crash behaviour of plastics/metal-hybrid composites by experimental and numerical methods

Plastics materials are nowadays used in many structural applications for the substitution of metals with respect to weight reduction. In order to utilize the high freedom of design and the light-weight potential of plastics materials in crash-relevant structural parts, so-called hybrid composites which combine the high rigidity and strength of steel with the advantages of plastics materials are investigated in the outlined research. Thereby, the joining of both materials as well as the design by means of numerical methods such as the finite element analysis (FEA) are challenges which have to be met. A new approach in joining is based on the modified arc welding process where metal pin structures are formed in one working step and subsequently welded onto the surface. The pins are formed with ball-shaped, cylindrical or spiky ends and produced directly from the welding wire without requiring additional pre-fabricated components such as studs or similar. This allows the small-scale surface structuring of metal components that can be adapted optimally for a form fit on the respective plastics structure. Subsequently, injection molding is used for the application of the plastics material onto the pin-structured metal part in order to generate a positive fit between metal and plastics in an intrinsic joining process. An additional joining process, which is carried out after injection molding, is not required. Within the framework of the research presented, comprehensive mechanical tests are presented to illustrate the suitability of pin-structured metal-hybrid composites in crash applications. In comparison to structures which are in particular exposed to static loads and therefore designed to exhibit maximum component strength, crash applications are designed to fail in a continuous process to achieve maximum energy consumption. The outlined research illustrates the enhanced failure behavior of pin-structured plastics/metal-hybrid composites and the increased energy consumption under impact loading. Moreover, a comparison between pin structuring and laser structuring with regard to the obtainable mechanical properties under impact loading is given. Concluding, the current potential and weak points in the simulation of plastics/metal-hybrid structures using FEA is presented and discussed.     

On the linear friction welding process of aluminum alloys: Experimental insights through process monitoring

Linear friction welding is a solid-state joining process for non-axisymmetric components in which joining of materials is obtained through the relative motion of two components under pressure. In the process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and eventually bonding conditions. A dedicated fixture was equipped with sensors for the in-process acquisition of variables regarding kinematics, dynamics and temperature levels. The results of an experimental campaign aimed to weld AA6082-T6 aluminum alloy parts are presented and a process window is identified for the used alloy.     

钛合金斜盘模锻成形工艺

通过对钛合金斜盘的结构特点和材质性能进行分析,提出钛合金斜盘模锻成形工艺;介绍了钛合金斜盘模锻工艺流程、热处理规范以及工艺要求,并进行工艺试制和应用.实践证明：合理制定工艺流程和热处理规范、优化毛坯结构以及加强过程质量控制,采用模锻成形工艺是可以锻造出复杂、弯曲类钛合金斜盘毛坯.     

NiCr20TiAl阀杆阀碟锻造工艺研究

分析了NiCr20TiAl的材料及锻造工艺特性,结合NiCr20TiAl以往锻造工艺和经验教训,通过优化锻造工艺参数,获得良好的微观组织,提高了锻件的综合力学性能。NiCr20TiAl阀杆阀碟的批量生产检验结果表明,采用优化的锻造工艺,锻件能满足技术要求,从而成功实现NiCr20TiAl阀杆阀碟的国产化制造。     

Process Design for Hybrid Sheet Metal Components

The global trends towards improving fuel efficiency and reducing CO_2 emissions are the key drivers for lightweight solutions. In sheet metal processing, this can be achieved by the use of materials with a supreme strength-toweight and stiffness-to-weight ratio. Besides monolithic materials such as high-strength or light metals, in particular metal–plastic composite sheets are able to provide outstanding mechanical properties. Thus, the adaption of conventional, wellestablished forming methods for the processing of hybrid sheet metals is a current challenge for the sheet metal working industry. In this work, the planning phase for a conventional sheet metal forming process is studied aiming at the forming of metal–plastic composite sheets. The single process steps like material characterization, FE analysis, tool design and development of robust process parameters are studied in detail and adapted to the specific properties of metal–plastic composites. In material characterization, the model of the hybrid laminate needs to represent not only the mechanical properties of the individual combined materials, but also needs to reflect the behaviour of the interface zone between them.Based on experience, there is a strong dependency on temperature as well as strain rate. While monolithic materials show a moderate anisotropic behaviour, loads on laminates in different directions generate different strain states and completely different failure modes. During the FE analysis, thermo-mechanic and thermo-dynamic effects influence the temperature distribution within tool and work pieces and subsequently the forming behaviour. During try out and production phase,those additional influencing factors are limiting the process window even more and therefore need to be considered for the design of a robust forming process. A roadmap for sheet metal forming adjusted to metal–plastic composites is presented in this paper.     

Friction stir welding between extrusions and laminates

Current market demands drive companies to innovate their production techniques to improve products and simultaneously hold down costs. In the search for solutions aimed at an optimization of production processes, semi-finished products in aluminium alloys very definitely play a significant role. Moreover, the assembly of extruded parts with laminates may result in considerable difficulties, especially in relation to distortions or generated residual stress and process productivity. A solution to these issues may be found in the application of friction stir welding (FSW), characterized by low thermal input and high productivity. The asymmetry of the FSW process determines a different thermal input to the edges of the pieces to be joined. This aspect can be exploited when it is necessary to join pieces characterized by a very different thermal lag, as occurs in the case of joining extruded products and sheeting. This study aims to identify optimal FW parameters, placing particular attention on heat transferred to materials so as to provide an adequate thermal input that will allow for compensation of the different thermal capacity of the pieces in question.     

Roll forming of branched profiles

Due to the new mass forming process “linear flow splitting” forming of branched profiles in integral style out of sheet metal without joining, lamination of material or heating of the semi-finished part becomes feasible. Since the resulting flanges provide extra stiffness without increasing the weight of the semi-finished product, split profiles are suitable especially for lightweight applications. The combination of the linear flow splitting process with a following roll-forming process enables the continuous production of one- or multi-chambered profiles with free flanges. In this paper phenomena occurring during roll forming of branched profiles are described and discussed.     

Joining similar and dissimilar advanced engineered materials

The typically specialized property combinations associated with advanced materials, combined with a desire for monolithic structures to maximize efficiency and performance, requires their effective joining. Through proper joining process selection and parameter optimization, both similar and ultimately dissimilar combinations of materials can be joined to produce high-performance components and systems.