Papers by Keyword: Incremental

Abstract: During a tube bending process the wall thickness distribution plays an important role concerning the process limits. Especially the wall thinning at the extrados of the tube is crucial. The wall thickness in a combined tube bending and tube spinning process will be analyzed. Therefore, possible stages of complexity are presented to show the possibilities of such a process combination. Based on this the interactions between the bending and spinning process on the wall thickness distribution will be discussed. Finally, a diagram will show how to adjust the wall thickness at the extrados of the tube only by adapting the tube spinning process.

Abstract: In this paper, Xi'an city housing market as the research object, focuses on the analysis of the inherent relationship between the housing stock market and incremental housing market, the development and the use of four quadrant model and regression analysis method to analyze the Xi'an real estate market. Development experience of Shanghai city housing market, put forward specific proposals for Xi'an City, to promote the healthy development of the housing market.

Abstract: The Incremental Profile Forming process (IPF) is a new method to manufacture tubes and profiles with variable cross-section design along the centre-line of the profile. The innovative process design enables the combination of high workpiece complexity and high process flexibility. For this reason, a machine concept was developed and finally a prototype realized. The new machine consists of eight numerically controlled axes, which allow the processing of thinwalled tubes and profiles with a maximum diameter of 80 mm. The design of the machine combined with the control system leads to a forming technology with a high degree of flexibility, which is an advantage of the process. Depending on the final workpiece shape the forming process proceeds in several steps and can therefore be considered as an incremental forming process. Furthermore, the tool concept supports both a kinematical and a form-closed forming process.

Abstract: Incremental sheet forming (ISF) is a method to form a sheet metal into desired shape and surface features in a batch production series. This method includes forming a clamped sheet metal in controlled conditions by a CNC milling machine, lathe machine or a robot. In this study, the effects of forming parameters on the amount of stretch in stainless steel sheet using a CNC milling machine have been investigated. A ball-point shaped tool made of a bronze alloy was fabricated and used throughout the experiments. The tool acted as the indenter that formed the stainless steel sheet into a small pyramid-like shape. The results showed that as the spindle speed and feed rate increased, the amount of sheet stretch also increased, up to a point where the sheet could not stretch anymore and the process changed from forming to shear thinning and chipping. In addition, the surface quality of the part was badly affected at higher spindle speed and feed rate settings. The temperature of the lubrication oil was also measured during the process and the maximum temperature recorded was 45°C which remained constant until the end of the process. In conclusion, to obtain a good quality part while increasing the productivity of ISF, the optimized values of the feed rate and spindle speed in this work were found to be at 500 mm/min and 1000 rpm respectively.

Abstract: Locally Linear Embedding (LLE) is a batch method. When new sample is added, the whole algorithm must be run repeatedly and all the former computational results are discarded. In the paper, the LLE algorithm processing on new sample points is analyzed. For the insufficient precision of the processing of traditional incremental LLE, an incremental LLE algorithm based on non-negative constraints of the weights is proposed. Non-negative constraints of linear weights are imposed on the new sample points in the projection process. The simple fitting of the original algorithm from the engineering application is avoided by the proposed algorithm and the problem of the constantly updating of the whole manifold is solved at the case of new samples being added. Compared with the traditional incremental LLE method, S-curve simulation data and engineering examples analysis show the feasibility and effectiveness of the proposed algorithm.

Abstract: In this paper, the effective properties of magnetoelectroelastic heterogeneous materials with ellipsoidal multi-inclusions are modeled and numerically investigated. The modeling is based on the integral equation that takes into account the multi-coated effect as well as the magnetoelectroelastic interfacial operators and global and local concentration tensors. Various types and kinds of coatings can be considered. The effective properties are predicted based on various micromechanical models such as Mori-Tanaka, Self-Consistent and Incremental Self-Consistent. These properties are presented in terms of the volume fractions of the multi-coated inclusions, thicknesses of the coatings, type and kind of inclusions.

Abstract: This paper presents a method for increasing the speed and the positioning accuracy of the positioning systems with mechanical position feedback. The method consists in using a position transducer for real time determination of the position of the load and correcting this position using an adequate algorithm. It is preferable not to modify the construction of the positioning unit, allowing the user to decide when to use this correction method according to the practical application. An interesting solution to this problem is to use an external space-position finding sensing system, as presented in the paper.

Abstract: Shrinking is an incremental forming process and can be carried out using a driving machine, so called “Kraftformer”. It needs an upper and a lower shrinking tool, each of which has two moveable jaws as contact and force transform units. During every forming operation the tools clamp the metal sheet, so that the vertical forces from the upper tool are switched by the leverages inside the tools into the horizontal directions. The moveable jaws are practiced by the horizontal forces to compress the metal sheet. The shrinking of the metal sheet brings out the different three-dimensional forms. As a traditional manual forming method, economical productions can’t be reached for individualized sheet metal parts to achieve the customer’s demands. Hence, it is proposed to automate this forming process to reduce the manual work. The production strategies are to be deduced from the manual shrinking process. A direct way to get them is to simulate the forming process in a FEM-software environment. But within such a FEM-simulation it can take about even one hour only just to finish one forming step. Furthermore, an analytical modeling of the shrinking can’t be realized because of its complex procedures such as variation of contact conditions, material hardening. However, a pure geometric model can be established to demonstrate the change of the 3D-forms of the sheet metal parts. The respective forming parameters can be identified through the experiments. The simulation can take place only in a few seconds. This paper provides general information about the application of the manufacturing method and with it the qualification of shrinking as a manufacturing concept for the production of individualized sheet metal products.

Abstract: A new incremental sheet forming machine has been built in Cambridge and was commissioned in October 2004. The basis for the machine design is described, including estimates of tool forces, the need for access to the reverse side of the workpiece, and the need to cope with high horizontal loads at the tool tip. The tool-mounting has been designed to rotate freely but passively, and to allow for simple exchange of tool tips. The workpiece is mounted on a set of load cells providing a six degree of freedom constraint without moment loading of the cells. The initial operation of the machine is briefly described.