During the past decade great success has been achieved in the development of duplex and multilayer multi-functional surface systems. Among these surface systems outstanding properties have nanoscale multilayer coating...
During the past decade great success has been achieved in the development of duplex and multilayer multi-functional surface systems. Among these surface systems outstanding properties have nanoscale multilayer coatings. Within the framework of the M3-2S project funded in the 7th European Framework Programme, several nanoscale multilayer coatings have been developed and investigated for experimental and industrial validation. This paper shows the performance of TiN and TiN/CrN nanoscale multilayer coatings on WC cutting inserts when machining GJL250 cast iron. The thin films have been deposited by cathodic arc evaporation in an industrial PVD system. The multilayer deposition characteristic and its properties are shown. The inserts have been investigated in systematic cutting experiments of cast iron bars on a turning machine specifically equipped for force measurements, accompanied by wear determination. Furthermore, equivalent experiments have been carried out on an industrial turning unit. Industrial validation criteria have been applied to assess the comparative performance of the coatings. The choice of the material and the machined parts is driven by an interest in automotive applications. The industrial tests show the need to further optimise the multi-scale modelling approach in order to reduce the lead time of the coating development as well as to improve simulation reliability.
The basic principle of Electrochemical Machining is an anodic dissolution of metallic work pieces at their interface to a liquid ion conductor, called electrolyte, under the influence of electric charge transport. Ele...
详细信息
ISBN:
(纸本)9780955308291
The basic principle of Electrochemical Machining is an anodic dissolution of metallic work pieces at their interface to a liquid ion conductor, called electrolyte, under the influence of electric charge transport. Electrochemical Machining with closed electrolytic free jet (Jet-ECM) is a new procedure which applies high current densities with a high degree of local removal, high localization of erosion and high surface quality [1]. Starting from this point machining of rotating work pieces by help of Jet-ECM is investigated [2]. Therefore a Jet-EC Turning prototype system was developed at Chemnitz University of technology. In this study experimental investigations for a characterization of the influence of different process parameters on the Jet-EC turning result are presented.
Due to their high specific workloads and small spatial requirements, shape memory alloys(SMA) possess an outstanding potential to serve as miniaturized positioning devices in small machinesThey provide sensory and act...
详细信息
Due to their high specific workloads and small spatial requirements, shape memory alloys(SMA) possess an outstanding potential to serve as miniaturized positioning devices in small machinesThey provide sensory and actory capabilities, being self-sufficient and a structure inherent control loopBased on its unique properties we present examples of SMA-actuated applications and methods of modeling systems, in which the material is used to compensate thermal induced strain in machine tool relevant applications and show how the overall system design can be achieved.
Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet t...
Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy‐efficient automobiles. The manganese‐boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press‐hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro‐bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.
The consideration of energy-related parameters is already in the planning phase an important step towards an energy-autonomous factory. Using Virtual Reality (VR) gives planners an important basis for decision-making ...
详细信息
The consideration of energy-related parameters is already in the planning phase an important step towards an energy-autonomous factory. Using Virtual Reality (VR) gives planners an important basis for decision-making with regards to drafting the layout. This potential should also be used for incorporating energy-related parameters. This paper introduces the coupling of a 2D planning system with a VR environment as the basis for the development of an energy-sensitive planning system. A prerequisite for considering energy-related parameters is recording and visualizing them. Therefore, the second part of the paper deals with energy visualization within a machine at the micro level.
The research of energy storage systems in the DC link of a machine tool is focused on the choice of the appropriate type of the energy storage system (passive or active) and its control strategy considering better ene...
详细信息
ISBN:
(纸本)9781612841670
The research of energy storage systems in the DC link of a machine tool is focused on the choice of the appropriate type of the energy storage system (passive or active) and its control strategy considering better energy efficiency. For the control strategy of the DC/DC converter two ways were taken into account: the proportional-integral and predictive control strategies. The energy consumption model of the drive group was developed in Matlab/SimPowerSystems for quantitative comparisons of the proposed energy storage systems. The model was validated by measurements of energy consumption in the drive unit of a machining centre.
In the present paper the influence of a higher setting velocity in the joining process of self piercing solid‐rivets is shown. In the conventional process tool velocities well below 1 m/s are common. The present rese...
In the present paper the influence of a higher setting velocity in the joining process of self piercing solid‐rivets is shown. In the conventional process tool velocities well below 1 m/s are common. The present research results show the potential of increasing them in the range of about 5 m/s. The results are especially relevant for joining high‐strength steels. These steel sheets often cause problems in the process of riveting mixed materials, e. g. aluminium‐steel compound. The high strength of the steel sometimes leads to undesirable material flow in the joining process or unwanted burr development. These effects, which are described in detail in the article, can be reduced significantly for the investigated cases by the use of higher tool velocities. Using a high speed camera and a load cell, a test setup based on a drop tower was realized. It was used to time the force signals and the motion profile of the high speed riveting process. The results of the force analysis show an oscillating force progression. Within a numerical research the principal effects influencing the results of the riveting process can be shown. It was found that the pulse‐like force transmission between riveting machine and punch, results in various vibrations especially of long and thin tool parts. Hence the rivet penetrates the sheet metal with non‐uniform velocities. As a result the early indentation of die into the lower sheet metal at the beginning of the process is reduced, so that the final process step provides a sufficient material flow into the circular rivet groove. A strain‐rate dependent process model with elastic tool properties and consideration of inertia effects is presented.
The fabrication of high aspect ratio microstructures is very challenging, especially when the work piece material is hard to machine. Electro Discharge Machining (EDM) offers a contact- and nearly force free way of mi...
详细信息
ISBN:
(纸本)9780955308291
The fabrication of high aspect ratio microstructures is very challenging, especially when the work piece material is hard to machine. Electro Discharge Machining (EDM) offers a contact- and nearly force free way of micromachining and is therefore an appropriate means to producing microstructures. One key obstacle for a precise machining by micro-EDM is the tool wear. When ED-machining microstructures process speed, stability and thus tool wear are related to the aspect ratio of the structures. In this study, tool wear ratio within different stages of the EDM process is analysed when machining high aspect ratio micro bores in steel. Experiments with bores of different depths show the correlation between the stage of the process and the flushing conditions on the one hand and the tool wear ratio on the other hand. Thus, it is possible to find and apply optimized parameters for the different process stages. A better understanding of the tool wear will help to minimize it, reducing the cost of the tools and enhancing the precision of the process. This also shall allow an enhancement of the process speed because the need for flushing material out of the bore is reduced by the amount of tool material that can be saved.
暂无评论