Recent Developments and Future Challenges in Incremental Sheet Forming of Aluminium and Aluminium Alloy Sheets

Due to a favourable strength-to-density ratio, aluminium and its alloys are increasingly used in the automotive, aviation and space industries for the fabrication of skins and other structural elements. This article explores the opportunities for and limitations of using Single- and Two Point Incremental Sheet Forming techniques to form sheets from aluminium and its alloys. Incremental Sheet Forming (ISF) methods are designed to increase the efficiency of processing in low- and medium-batch production because (i) it does not require the production of a matrix and (ii) the forming time is much higher than in conventional methods of sheet metal forming. The tool in the form of a rotating mandrel gradually sinks into the sheet, thus leading to an increase in the degree of deformation of the material. This article provides an overview of the published results of research on the influence of the parameters of the ISF process (feed rate, tool rotational speed, step size), tool path strategy, friction conditions and process temperature on the formability and surface quality of the workpieces. This study summarises the latest development trends in experimental research on, and computer simulation using, the finite element method of ISF processes conducted in cold forming conditions and at elevated temperature. Possible directions for further research are also identified.

Effect of process parameters on formability in two-point incremental forming-machining of planar and twisted AA5083 blades

The deformation machining process (DMP) involves machining and incremental forming of thin structures. It can be applied for manufacturing products such as curved-surface blades without using 5-axis computerised numerical control machines. This work presents the effect of tool diameter and forming temperature on spring-back and dimensional accuracy of a simple fabricated part. The results of the first phase of the study are utilised to design the fabrication process of a curved surface blade. A feature-based algorithm is used to design the tool path for the forming process. The dimensional accuracy of the final product is improved through warm forming, two-point incremental forming, and extension of the bending zone to the outside of the product edges. The results show that DMP can be used to fabricate complex curved-surface workpieces with acceptable dimensional accuracy.

Tool-Path Planning Method For Kinematics Optimization of Blade Machining On Five-Axis Machine Tool

Planning tool-paths on free-form surfaces is a widely discussed issue. However, traditional methods of generating paths capable of meeting all the requirements of blade machining remain challenging. In this study, a new iso-parametric path-planning strategy based on a novel parameterization method combined with the conformal transformation theory was proposed. The proposed method could adapt to the curvature characteristics of the blade surface, improving the kinematic performance of the machining process, reducing multi-axis coordinated motion control complexity, and improving machining quality. The proposed method was then compared with three traditional methods. The influence of the tool-path on the kinematic performance of the machine tool was quantitatively examined based on the kinematics models of two different machine tools. A large cutting depth milling experiment was conducted to verify that kinematics optimization could improve machining quality. The proposed method provides a more reasonable path-planning approach for blade machining on a five-axis machine tool, which is of great significance in reducing the cost of blade machining and the risks of blade failure. Moreover, it is of great significance for the large-scale automated production of blades.

METHOD FOR CALCULATING CUTTING FORCES BY MODELING CAD WITH A SYSTEM OF GEOMETRIC CUTTING PARAMETERS WITH RADIAL MILLS

The accuracy of processing surfaces of a complex profile largely depends on the selected processing strategy, which will allow creating the same, within certain limits, power characteristics of the shaping process at the intervals of the programmed tool path. In this case, it becomes possible to include tuning modules in programs for CNC machines that form vector values of corrections in certain areas, as reactors for elastic deformations of the cutting process. Therefore, it is especially important to know the modulus and direction of the resulting cutting force vector, which does not necessarily coincide with the feed direction. The purpose of this work is to build a method for calculating cutting forces by modeling the geometric parameters of a cut with a CAD system, a cutter with a nonlinear generatrix. Solid modeling of the process is based on the Boolean operations of "intersection" and "subtraction" of 3D objects: the teeth of a radius cutter with a helical cutting edge and a workpiece "moving" at a feed rate. The tool for the implementation of this method is a software module created on the basis of API functions, the input data for which are: a 3D tool and a workpiece, the equation of the trajectory of its movement and the parameters of the infeed movement. Targeting API properties, the application makes it possible to simulate various trajectories, helical or trochoidal, when machining complex surfaces. In the future, it is possible to take into account the plastic deformation processes in the chip formation zone in the model by connecting external modules. In the course of the conducted research on milling with radial end mills with a helical cutting edge, when two or more teeth are within the arc of contact, it was determined by 3D modeling how much thickness and width the layer cuts off each of the teeth during the feed per revolution. Consequently, in the process of shaping, normal and tangential cutting forces, which are different in direction and modulus, are present as a function of the angle of rotation of the cutter. Therefore, the concept of "circumferential force on the cutter", accepted in the theory of cutting, as a certain constant component of the process, can introduce an error when considering the causes of the excitation mechanism of vibrations of different nature that arise in the processing zone.

Improving the efficiency of machining on metal-cutting machines by aligning the CNC program and the evolutionarily changing cutting dynamics

Modern machines with high accuracy provide an accordance of the trajectories of the executive elements to the CNC program. However, this is not guarantee the same accuracy of manufacturing the part. One of the main reasons for the formation of the geometric defects is the elastic deformations of the tool and the workpiece. It is caused by variations of the cutting forces, changes in the rigidity of the workpiece along the tool path. It depends on changes of the properties of the dynamic link formed by cutting. Therefore, there is a problem of synergetic aligning of controlled trajectories with changing cutting properties. In the article, the regularities of the alignment of external control and internal dynamics are considered on the basis of mathematical modeling of the system in which the trajectories of the executive elements are controlled. The case of accounting the a priori given law of changes of the stiffness of the workpiece is considered. The effectiveness of the alignment is estimated by the reduced costs while ensuring the required quality of the parts.

Optimization of Tool Path Length on Three-Dimensional Drilling Application Using Ant Colony Algorithm

The lower machining time is important characteristic in the drilling machining process. Drilling process costs will increase if the machining time is high. Therefore, the main objective of this research is to develop Ant Colony Algorithm (ACO) to reduce the machining time by obtain the optimal tool path length. By using this algorithm, it can minimize the tool path length and significantly decreasing the machining time of drilling process. Simulating in 3-dimensional drilling on ACO has been constructed to minimize the shortest path of the drilling process. There are two type of workpiece has been used, which is simple block with 10 holes and complex block design that has 154 holes. ACO algorithm has been developed in Matlab R2017b to determine the optimal parameters of ACO of tool path length in drilling. Besides, simulation also has been done to investigate the effect of ACO parameter which is weight of pheromone (α), weight of trail (β), evaporation coefficient (e), and number of iterations. As a result, by define the parameter of iteration number at 900, the optimum parameter of weight of pheromone (α) is 5, weight of trail (β) is 4 and evaporation coefficient (e) is 0.4. Based on these parameters, the minimal tool path length obtain for simple and complex model are 286.965 mm and 6770.9860 mm respectively. Then, the result of tool path length of ACO simulation has been compared with the Mastercam outcome. ACO achieves a total tool path length of 286.965 mm while Mastercam achieved 569.878 mm for simple block design. Meanwhile, for complex block design, ACO produces a total tool path length of 6770.9860 mm while Mastercam has generate 55828.9050 mm of tool path length. By comparing these two approaches, ACO and Mastercam, ACO has that the short total tool path length by 49.64% on simple block design and 87.87% for complex block design.

Processing of quasi-equidistant surfaces with the detection of the dependence of the roughness parameters on the tool pitch in the cam system

This article discusses the basic principles of generating a tool path when processing quasi-equidistant surfaces. The review and analysis of the origin of the automation of technological preparation of production in the world is carried out. The concept of integrated automated production is revealed. Considered are the leading enterprises that were among the first to introduce computer-aided design systems. The article discusses technologies for processing complex surfaces with the maximum removal of the metal layer from the work piece, with the maximum approximation to the given shape. The types of complex spherical surfaces have been identified, the processing of which is a complex technological process that requires a high level of qualifications of a specialist and expensive equipment. Before the introduction of automated machine control, such types of complex surfaces were almost impossible to process, the geometry was only close to the real one. Here we consider a modern CAM-system, which is a complex software package. Over the past decade, several generations of CAM systems have changed. When forming the tool path, it is possible to use the functions of their viewing and editing. In most cases, the system automatically generates the tool path based on the cutting geometry and machining parameters. The authors proposed a method for creating a machining path in the NX CAM environment. In this work, the optimal trajectory of the tool movement is determined, the cutting pattern is selected for processing quasi-equidistant surfaces, the cutting modes, the cutting tool, and the overlap step between passes are determined.