Michael Trompeter

Multifunctional Lightweight Structures from Tailored Cladded Blanks

In this paper, the use of partially or tailored cladded blanks is proposed for the production of multifunctional lightweight components. Therefore, the non-joined sheet areas will be formed to hollow structures by hydroforming subsequent to the partial cladding operation. The paper presents results of research work on the production processes and potential applications of partially cladded blanks in the field of thermal engineering and automotive engineering. Furthermore, it is focused on possible developments regarding the use of multiple materials and process combinations for sophisticated applications e.g. in the field of lightweight constructions.

Die Surface Structures and Hydrostatic Pressure System for the Material Flow Control in High-Pressure Sheet Metal Forming

A promising approach to control the material flow within deep drawing and workingmedia based forming processes is the structuring of the tool surfaces in the contact zones between workpiece and die. In order to obtain a sufficient and an optimised material flow respectively – especially for non-symmetric or non-uniform workpiece geometries – a locally adapted distribution of surface structures is a practicable solution. The macroscopic, and also the microscopic surface structures can be manufactured sufficiently by means of a high-speed cutting process. The shape of the tool surface structure has a significant influence on the tribological conditions between workpiece and die. To adjust the surface structure distribution to the required material flow distribution, detailed knowledge about the correlation of the material flow from the tribological conditions between sheet and the forming tool is required. A further innovative approach, particularly for decreasing the friction coefficient, is the use of an innovative hydrostatic pressure system using fluid ducts. Its functional principle is based on the reduction of the contact shear stress at the sheet surface in the contact zone with the forming tool by means of locally applying a hydrostatic fluid pressure. To obtain information about the correlation of the material flow from the tool surface structures and from the parameters of the hydrostatic pressure system respectively, fundamental investigations have been carried out. In order to optimise the material flow, these toolbased approaches can be used as stand-alone solution, or in addition to other systems. If the surface structures and a hydrostatic pressure system are used in combination with the multi-point blank holder, which has already been qualified for the high-pressure sheet metal forming (HBU), a powerful system for the material flow control is available.

An Experimental and Numerical Investigation on Polymer Melt Injected Sheet Metal Forming

Manufacturing Technology Today, December 2015 29 Manufacturing technology abstracts The topics on various aspects of manufacturing technology can be discussed in term of concepts, state of the art, research, standards, implementations, running experiments, applications, and industrial case studies. Authors from both research and industry contributions are invited to submit complete unpublished papers, which are not under review in any other conference or journal. Contact: The Editor, Manufacturing Technology Today (MTT) Email: mtt.cmti@nic.in CASTING & FouNDRy PRACTICE 30 CoATING & FINISHING 30

Potential of Melted Polymer as Pressure Medium in Sheet Metal Forming

The development of manufacturing methods for producing plastic-metal hybrid structures has already opened new possibilities for lightweight design. Contrarily to the existing technologies i.e. Insert, Outsert and Hybrid Technology, the new forming process “Polymer Injection Forming” (PIF) offers the advantages associated with injection moulding technology and hydroforming technology in a way that hybrid structures can be produced in a single step. The polymer which is used as pressure medium in a melted state to form geometrical features in the sheet metal remains as a functional part in the final hybrid structure. This paper focuses on the experimental investigation of Polymer Injection Forming. Particularly, the interaction between process parameters of injection moulding including injection pressure, cavity pressure, volume flow rate, melt temperature and the resulting part properties e.g. shape and strain distribution of the sheet metal structure from the preliminary results are discussed. The experiments comprise the bulging of a (free form) dome geometry and simple cup geometry of Aluminium and steel sheets by using thermoplastic Polypropylene (PP) as working medium.

Material Behavior of an Ultra-High-Performance Concrete Forming Die for Sheet Metal Hydroforming

New sheet metal forming technique and low cost forming die development has resulted from economic requirements and an increasing number of part variants. To form detailed and uniform sheet metal contours in the range of elastic material behavior of the die material, these dies have to withstand approximate pressures of 100 MPa (14.50 ksi) for sheet metal hydroforming. A promising approach to cost-efficient die production is ultra high performance concrete (UHPC) use, particularly for high pressure sheet metal hydroforming. Uniaxial and triaxial compressive stress state stress-strain behavior was investigated through experimentation at various ages for a fine grained UHPC. Three concrete cylinder confinements were additionally tested to achieve a multiaxial stress state. After fabrication of a forming tool prototype, its performance was analyzed in applying a fluid pressure up to 90 MPa (13.05 ksi). The formed sheet shape accuracy and ultimate prototype load were examined. There was also determination of the friction coefficient between sheet metal and concrete. Forming tests have demonstrated that the investigated UHPC can be successfully used as sheet metal hydroforming die material.

Wirkmedienbasierte Herstellung mehrzelliger Blechstrukturen für den Nutzfahrzeug-Leichtbau

Grosflachige, Mehrzellige Blechstrukturen mit hexagonaler Hockergeometrie haben ein geringes Gewicht bei hoher Festigkeit. Mithilfe eines schrittweisen Fertigungsablaufs konnten die Hockerbleche mit variabler Breite und Lange bis zu einer Flache von 1800 x 2000 mm auf einer konventionellen 1000-t-Tiefziehpresse umgeformt werden. Die Hockerbleche weisen eine hohe Form- und Masgenauigkeit auf, die das passgenaue Fugen von zwei Hockerblechen zu sehr biege- und torsionssteifen Wabenplatten sicherstellt. Die hergestellten Wabenplatten wurden erfolgreich als Leichtbautrennwand fur den Anwendungsbereich des Nutzfahrzeugbaus getestet.

Hydroforming of Large-Area Multi-Cell Sheet Metal Structures

This paper presents a sectionwise hydroforming technique for manufacturing of large-area multi-cell sheet metal structures in terms of hump plates. The sectionwise hydroforming technique allows production of hump sheets with variable width and length. The hump plates are based on hexagonal hump geometry. The hump height is optimized for the application as a partition wall in light utility vehicles. Manufactured hump sheets feature a high contour accuracy which allows joining of two hump sheets to a large-area hump plate (up to 1,800 x 2,000 mm). The hump plates have been successfully tested in a load test which proves their potential for light utility vehicles.

Neue Halbzeuge für das Innenhochdruck-Umformen

Partiell plattierte Platinen sind neuartige Doppelblech- bzw. Multiblech-Halbzeuge, die durch einen Walzplattierprozess in definierten Blechbereichen vollflachig miteinander gefugt sind, so dass diese an bestimmten Stellen einen festen Werkstoffverbund bilden. Durch eine Druckbeaufschlagung der ungefugten Bereiche des Doppelblechverbundes konnen mittels innovativer Innenhochdruck-Umformprozesse — kurz IHU — Blechformteile komplexer Geometrie hergestellt werden.

MANUFACTURING AND FORMING OF PARTIALLY CLADDED DOUBLE BLANKS

The paper presents the manufacturing and hydroforming of partially cladded double blanks. This novel, semi-finished product can be produced by partial cold roll-bonded cladding. By printing a separating layer onto the contact surface beforehand, cold roll-bonded cladding, defined blank areas remain unjoined which can be bulged during hydroforming to a complex part. Favorable advantages result from the time and cost effective continuous joining process and the extended potential for a material combination aimed at optimally adapted multi-layer composites. Experimental investigations could prove a good joining strength and assure that the cold roll-bonded cladding does not significantly decrease the formability of the cladded blank material. Considering a heat exchanger and a roof rail, the experimental investigations could prove the producibility of parts based on partially cladded blanks and have shown an adequate shape accuracy of the produced parts.

INNOVATIVE FORMING TECHNOLOGY AS A KEY FOR THE EFFECTIVE MANUFACTURING OF LIGHTWEIGHT STRUCTURES

Current tends in car body or rail traffic engineering aim at the realization of modern lightweight structures. In this context, demanding technological and economical requirements like the use of high strength materials, the forming of very complex geometries, and the reduction of costs, particularly with regard to low volume production, must be achieved. Novel approaches in the field of sheet metal hydroforming are able to overcome existing limitations of conventional forming technologies and feature a higher potential for an effective manufacturing of lightweight structures. This paper shows the current research work at the Institute of Forming Technology and Lightweight Construction (IUL) in the face of sheet metal hydroforming with a special focus on the design of tool systems.