This study deals with the development of a CAM system that considers the deforming process for a forgingtype rapid prototyping system. An industrial robot that has high degrees of freedom is employed ...to handle the hammering unit. A special CAM system suitable for the hammering work is developed using parametric curve interpolation. The tool path is generated considering continuity in order to avoid fracture or breakage. Using the system, metal hammering experiments are carried out. The system successfully shaped workpieces according to the generated path. The experimental results confirm the ability of the system to improve, owing to the parametric curve interpolation, forming properties.
In this paper the effect of the springback on the bending operation of different materials and alloys have been studied. Dies were designed and constructed in different shape ( U-die , V-die) for ...several sheet’s thickness. Two types of alloys were used; Aluminum Alloy 7020 T6 and Brass Alloy. These alloys have different sheet thickness (2, 4, 6 and 8) mm. Aluminum alloys are heated to 270 °C and 330°C with cooling in the furnace for 90 min. while the brass alloys heated to 300, 320, 340 and 420 °C with cooling for 2 hours in furnace. Bending was done by using the press of 80 ton. The springback is calculated by published equation. It can be concluded that, the springback phenomenon caused to enlarge the external dimensions when releasing the load and thick material have less springback due to the enlarge of the plastic deformation. It’s found that the die’s shapes have great effect on the springback, and when the temperature of the specimen is increased, caused decreased in the springback.
This article addresses process, stamping, and manufacturing engineers, as well as tool designers (prototype and series production tools), and press shop planners in the range of metal forming. The ...paper deals with methods of modelling and simulating the metal forming process and their application in product design, production, and forming process planning. In models usually applied major effects on the forming process are neglected. For instance, the elastic behaviour of presses and die tools is not considered in process and tool planning. Thus, reworking of tools is a consequence of this model oversimplification. The paper illustrates how interactions between forming press, die tool and metal forming processes can be modelled by enhancing conventional FE models. Several examples demonstrate the information value of the Advanced Forming Process Model (AFPM).
Amorphous melt-spun ribbons of an Nd
15Fe
77B
8 magnetic alloy were consolidated into bulk form by the compression shearing method. X-ray diffraction and differential scanning calorimetry studies ...confirmed that the amorphous structure was well maintained in the compacted material. No appreciable crystallites were seen in the microstructure of the compacted material. The magnetic properties of the amorphous bulk material were comparable to those of the amorphous melt-spun ribbon.
In this paper, a process model of the controlled forming process was proposed based on Response Surface Methodology (RSM). The forming process was controlled through adjusting the blank holder force ...(BHF) varied with the time and other process parameters. Due to the wide application and the high efficiency of the Finite Element Method (FEM), this is the chief tool used instead of experiments to carry out the controlled forming process. Deep drawing processes of material SPCC were simulated, and the simulation results were verified by the experiments. The forming processes with several types of time variant BHF were simulated and compared to find a suitable one to achieve our desired product shape. The comparison implied that the staircase-shaped time variant BHF can direct the strain path to the desired place to acquire a targeted product.
Then the process model was built up using RSM to the forming process with time variant BHF and friction coefficient. The equations explored the relationship between the principal strain of fracture risk elements and the working parameters, including BHF. Three–dimensional (3D) principal strain surfaces of the element were drawn, which visualised the relationship between the principal strain and the working parameters, especially BHF. Using the model, it is feasible to acquire a fracture-free product through regulating the BHF profile.
Nowadays, the simulation of forming process is rather well integrated in the industrial numerical codes. However, in order to take into account the possible modifications of the tool during rates of ...working, a dedicated numerical software is currently developed within the laboratory Roberval, this software allows to simulate forming process. The tool is discretized by boundary elements and the product, which is subjected to non-linearities, is discretized by finite elements. For the product, an isotrope law of behaviour is integrated, and the damage is taken into account by the uncoupled Rice and Tracey model. This paper deals with a contact algorithm, coupling boundary elements and finite elements, programmed in the software KSP. For that, friction is described by the Coulomb law and the resolution of contact problems is done by the penalty method. An adaptive step has been developed in order to increase the robustness of the contact algorithm.
Powder Forging: Today and Tomorrow Dorofeev, V. Yu; Dorofeev, Yu. G.
Powder metallurgy and metal ceramics,
11/2013, Letnik:
52, Številka:
7-8
Journal Article
Recenzirano
The current status and prospects of powder forging for producing structural engineering parts are discussed. The causes of the reduced scope of research in the field of powder forging in 1990–2010, ...as well as the advantages and disadvantages of the process, are analyzed. The method makes it possible to produce high-dense materials for high-stress applications. The complexity of parts’ shape is limited by the performances of hot-forging equipment in use. The need for substantial capital expenditures for basic and auxiliary equipment is the critical area of the process, so powder forging would not be appropriate for mass production of parts. Promising areas for the development of powder forging are identified.
To form cognitive radio nodes into a wireless ad-hoc network, generally, globally or locally common channels are assumed to be available or some channels are dynamically selected as locally common ...ones. However, a cognitive radio node is not licensed to any channel for communication. With dynamic channel availability, neither locally nor globally common channels could be assumed available. Therefore, in this study, a new approach for cognitive radio network formation is presented that is not constrained by the availability of common channels. The proposed approach is based on the ‘group’ concept. Activated cognitive radio nodes form multiple ‘groups’ according to some criteria. Each group consists of a head node, some gateway nodes and ordinary nodes. During sensing phase, nodes sense channels and negotiate the channel and time slot assignment; thus, during data transmitting phase, each node is able to communicate with its different neighbour nodes in assigned channels during given time slots. Hence, nodes can be connected together to form a network without common channels and the network connectivity is improved. This study presents the network forming process including neighbour node detection, node communication, group formation, time slot assignment, channel assignment and medium access control protocol. Finally, simulations are conducted to investigate the network connectivity.
The influence of equal-channel angular extrusion on the structure and mechanical properties of powder compacts with high initial porosity is studied. A compaction area whose size and density increase ...with the accumulated strain is discovered. After the third pass, the compaction area has 0.99 relative density, 845 MPa micro-hardness, 80 nm grains, and 530 MPa compression yield strength. Angular extrusion allows production of a powder material with high physical and mechanical characteristics from high-porous compacts in three passes.
In the present work some essential aspects related to the simulation of phase transformation during hot forming simulation are discussed. A new material model used for hot forming simulation in ...commercial finite element code LS-DYNA was applied. Experimental values and bibliographical data were used in order to find optimum input parameters. Based on these parameters a hypothetical hot forming process for a graded component part was simulated. Using tools at varied temperatures and with different thermal properties seems to be a feasible method to achieve a better control of the phase transitions during hot forming.
