Hinnerk Hagenah

Computer Assisted Design of Actuator Systems for Laser Micro Adjustment

The adjustment of micro system components with laser forming using especially designed sheet metal actuator systems is a new and promising technology. However, due to the complexity of the design challenge and the contradicting targets that have to be considered computer assistance for the design of the actuator systems is needed. In order to build such a system several steps have to be taken. First, the actuators have to be modeled with all necessary data. Second, quality criteria have to be defined and fully automated assessment modules for every single objective have to be implemented. And third, an optimization system which utilizes the assessment modules must be developed to improve an initial design. This paper presents a solution for each of these steps. It closes with first results of a reduced version of the system as well as an outlook on the next development steps.

Problem Specific Design of Actuators for Micro Adjustment

Ongoing miniaturisation of functional parts in electronic, optical and mechanical devices results in an increasing demand for precision. By means of laser beam forming of especially designed sheet metal parts within an assembly the needed high accuracy can be reached. The use of the so called actuators, their mounting within the assembly and their activation through laser irradiation are well known steps. The design however is a sophisticated process so far depending on the experience of the designer. It is often determined in a time consuming iterative process. In this paper concepts and methods for an assistance system for the designer of actuator geometries using kinematic chains will be presented.

Investigations on Three-Roll Bending of Plain Tubular Components

Bent metal tubes find a widespread application in many industrial sectors. Among different bending processes developed for the manufacturing of these components, three-roll bending is characterized by a high flexibility, as only one toolkit per tube diameter is necessary to form the required bending radius. In this type of forming process the part geometry is obtained by means of a relative movement of the die (setting roll) towards the fixed tools (bending and holding roll) with simultaneous feeding of the tube. This study describes the FE-model developed for the three-roll bending and presents first results of numerical investigations conducted on steel tubes made of carbon steel St37. By the FE-analysis great attention is paid on the modeling of the stiffness of the tool, on the description of the kinematics of the setting roll as well as on the characterization of the material behavior for the simulation. The results of the numerical investigations are compared with experiments conducted with a CNC-bending machine available at the Chair of Manufacturing Technology of the University of Erlangen. As a main criterion for the validation of the FE-model the radius of the tube at the extrados and the bending angle are chosen. The geometry of the part is measured by means of both optical and tactile measuring devices.

Introduction to sheet-bulk metal forming

Sheet-bulk metal forming as a new class of manufacturing processes is one of the possible answers production processes provide to the increasing demands on functional integration into light weight parts made of high strength steel. Research in this field is carried out in several places. The special issue was initiated by the Transregional Collaborative Research Centre 73. It contains newest results from this research initiative as well as international results in the field of sheet-bulk metal forming.

Optimization of the Heat Treatment Layout and Blank Outline of THTB

Tailored heat treated blanks (THTB) is the generic term for an innovative approach to enhance the formability of blanks made out of high strength steel or aluminum alloys. Key idea of the technology is the adaption of the mechanical properties by a local heat treatment. Based on the new property distribution, the material flow during the forming operation can be improved and the forming limit can be enhanced. In comparison to conventional temperature assisted approaches the forming is performed at room temperature and therefore all advantages of a cold forming process can be used. Most challenging within the application is the definition of the heat treatment layout. Up to now the layout is dimensioned in a time-consuming trial and error procedure. In this paper a new approach for the automatic optimization of the heat treatment layout and the blank outline is presented.

Investigation on the Process Parameters and Process Window of Three-Roll-Push-Bending

Three-roll-push-bending is a highly flexible method for the manufacturing of free-form bent tubes. The bending radius as target value is mainly determined by the position of the setting roll, defined by its axes P and Y. In industrial application the process design is carried out incrementally by trial-and-error. To avoid machine occupancy and to save expenditure of human labor, a lean offline process design is desirable. Furthermore, the technically possible parameter range is not fully used in common production processes. The machine’s behavior should be investigated in the complete range to find the optimal choice of process parameters for each case. For a methodical process design a reliable data basis had to be gained about the resulting bending radius depending on the position of the rolls. To achieve this, a parameter study was run where samples were taken covering the entire theoretically feasible parameter range. To determine the influence of the roll position, the measured data have been approximated by thin plate splines. The new data covers a considerably enlarged process window, which proved to have yet unused regions featuring low scatter.

Computer Assisted Design of Actuators for High Precision Adjustment in Micro Technology

Micro systems technology is expected to play a pivotal part in future product development both in scientific and industrial fields. Decreasing size and tolerances make mounting and joining operations quite a challenging task. Laser adjustment is a suitable technology to achieve the necessary accuracy by processing specifically designed actuators on which the functional elements have been mounted. Nowadays, the specifically tailored design of these actuators is performed by experts through an iterative process. In this paper we will present the concept and parts of the design and development of a computer based assistance system helping the designer define new actuator geometries. We will introduce a data model to describe already existing actuator geometries and summarise them in a construction catalogue. The adjustment task at stake is described by means of kinematic chains. The design of actuator geometry therefore boils down to the design of a kinematic chain. A suitable kinematic chain is sought for and computed using the Denavit-Hartenberg method which has been extended to handle closed kinematic chains as well.

Mechanical Response of Ti-6Al-4V Alloy on Deformation at Moderate Temperatures

Due to beneficial characteristics such as high specific strength, corrosion resistance and biocompatibility Ti-6Al-4V alloy has become the most important industrially produced titanium alloy during the last decades. Commonly used for aerospace technology and medical products, nowadays Ti-6Al-4V covers 50% of the worldwide produced titanium alloy parts. Different deformation operations as forging and casting as well as machining are used to shape titanium alloy components. For sheet metals, cost and time of fabrication can be reduced significantly via the near net shape technology sheet metal forming. Materials such as the α + β alloy Ti-6Al-4V with high yield stress and comparatively low elastic modules need to be formed at elevated temperatures to increase their formability. Numerical simulations are applied to calculate the forming behavior during the process and conclude the characteristics of the shaped part. Therefore in this paper the mechanical behavior of this titanium alloy is investigated by uniaxial tensile test within elevated temperatures ranging from 250 to 500 °C. Finally, the experimental results are adapted to models which predict the flow response in order to describe material behavior in finite element analysis of the forming process.

Multi-objective optimization of actuator system design for laser micro adjustment

Complex design processes require a high level of expertise and are time consuming. By assisting the engineer with a computer aided design system the design process can be accelerated and be made more reliable. Actuator system design for laser micro adjustment is complex and its challenges may be a hindrance for the application of laser micro adjustment. To overcome this obstacle a computer aided design system was developed which utilizes a multi-objective optimization algorithm to automatically improve actuator design. In this paper, the system and its components are presented. A special focus will be upon the assessment functions which allow the efficient assessment of an actuator design. An application example will be given to demonstrate the functionality of the design system.

Irradiation planning for automated treatment of psoriasis with a high-power excimer laser

American and European statistics have shown that 1-2 per cent of the human population is affected by the skin disease psoriasis. Recent research reports promising treatment results when irradiating skin areas affected by psoriasis with high powered excimer lasers with a wavelength of 308 nm. In order to apply the necessary high energy dose without hurting healthy parts of the skin new approaches regarding the system technology must be considered. The aim of the current research project is the development of a sensor-based, automated laser treatment system for psoriasis. In this paper we present the algorithms used to cope with the diffculties of irradiating irregularly shaped areas on curved surfaces with a predefined energy level using a pulsed laser. Patients prefer the treatment to take as little time as possible. This also helps to reduce costs. Thus the distribution of laser pulses on the surface to achieve the given energy level on every point of the surface has to be calculated within a limited time frame. The remainder of the paper will describe in detail an efficient method to plan and optimize the laser pulse distribution. Towards the end, some first results will be presented.