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Based on the numerical simulation, the deformation characteristics of incremental sheet punching (ISP) of perforated sheet with circular holes was studied. Combined with the experimental results, the feasibility of using the normalized Cockroft-Latham ductile fracture criteria to predict fracture of perforated sheet during the ISP process was verified. On the basis of above, the influence of the geometric parameters of perforated sheet on the formability was studied. The main conclusions are the major strain is much greater than the minor strain at the interval of holes on the side wall of the perforated sheet; the thickness at the short-axis edge of the hole is smaller than that at the long-axis edge obviously; and the maximum value of major strain of perforated plate decreases with the increase of straight diameter center distance ratio. It is feasible to predict fracture of perforated sheet during the ISP process by numerical simulation with normalized Cockroft-Latham ductile fracture criteria. [ABSTRACT FROM AUTHOR]

Considering the residual height of the sheet metal part surface formed by the point-pressing incremental forming method and the efficiency of the forming process, the candidate terminal cutter location points based on the latitudinal/longitudinal residual height were calculated firstly, and then adjusts the candidate terminal cutter location points that are beyond the maximum residual height. Finally, all the terminal cutter location points are obtained. Thus, while satisfying the maximum residual height, the pressing points are sparse as much as possible, which improves the forming efficiency. In addition, for the problem that the ordinary 3-axis CNC incremental forming cannot press the sheet in the different directions according to the surface features, a method for determining the spatial posture of the 5-axis pressing tool by adjusting the front angle and side dip angle was proposed so that the sheet metal can be pressed in different extrusion directions. According to the proposed 5-axis point-pressing incremental forming tool path generation method, the actual forming experiment was carried out, and the sheet metal part was successfully formed, which meets the residual height requirements and shows that the methods for the tool path generation and the spatial posture determination of the forming tool are feasible. In addition, a comparative experiment was conducted with the 5-axis consecutive incremental forming tool path under the same residual height conditions. Through the measurement and analysis of the experimental parts, it is concluded that the profiles of the sheet metal parts obtained under the two forming methods have a good geometrical agreement with the designed parts. However, the profile of the sheet metal part formed by the 5-axis point-pressing incremental forming tool path is closer to the designed part as a whole, and the thickness in the forming region is also slightly higher than that of the sheet metal part formed by the 5-axis consecutive incremental forming tool path. [ABSTRACT FROM AUTHOR]

For the past three decades, robotic machining has attracted a large amount of research interest owning to the benefit of cost efficiency, high flexibility and multi-functionality of industrial robot. Covering articles published on the subjects of robotic machining in the past 30 years or so; this paper aims to provide an up-to-date review of robotic machining research works, a critical analysis of publications that publish the research works, and an understanding of the future directions in the field. The research works are organised into two operation categories, low material removal rate (MRR) and high MRR, according their machining properties, and the research topics are reviewed and highlighted separately. Then, a set of statistical analysis is carried out in terms of published years and countries. Towards an applicable robotic machining, the future trends and key research points are identified at the end of this paper. [ABSTRACT FROM AUTHOR]

To carry out incremental sheet-punching process without adding any additional device on a common numerical control machine or a specialized incremental sheet-forming machine, a method was proposed by modifying the tool path generated by commercial CAD/CAM software. The method consists of a few steps: generating the tool path for the three dimensions model of the desired part, exporting the tool path as dispersed points, interpolating the tool points with liner polynomial, modifying the tool points to sinusoid in the vertical direction to the clamped sheet, exporting the new sinusoidal tool path, etc. Different geometries were formed using two kinds of sheets, non-perforated sheet and perforated sheet, to determine the feasibility of the method. Furthermore, the effects of the wavelength and the amplitude of the sinusoidal tool path on material formability and surface quality of the formed sheet were analyzed on the basis of forming truncated funnels and pyramids. The results show that it is feasible to form both non-perforated sheet and perforated sheet by the proposed method. Additionally, they show that the wavelength has obvious influence on material formability and surface quality while the amplitude only influences material formability significantly. [ABSTRACT FROM AUTHOR]

Machining using industrial robots is currently limited to applications with low geometrical accuracies and soft materials. This paper analyzes the sources of errors in robotic machining and characterizes them in amplitude and frequency. Experiments under different conditions represent a typical set of industrial applications and allow a qualified evaluation. Based on this analysis, a modular approach is proposed to overcome these obstacles, applied both during program generation (offline) and execution (online). Predictive offline compensation of machining errors is achieved by means of an innovative programming system, based on kinematic and dynamic robot models. Real-time adaptive machining error compensation is also provided by sensing the real robot positions with an innovative tracking system and corrective feedback to both the robot and an additional high-dynamic compensation mechanism on piezo-actuator basis. [ABSTRACT FROM AUTHOR]

Incremental forming process is a method for rapid prototyping and low-volume production. Recent ideas have been introduced as 'incremental sheet metal punching.' In this study, a new analytical modeling of the process with respect to the forming mechanism and slip line field has been presented. The analysis sheet formation in this process can be divided into two stages: penetration and curve making. At the penetration stage, both approaches of the upper bound method and slip line field were used to calculate the pressure and velocity of the punch. At the second stage, the estimated slip line field was assumed for curve making. This leads to making a suitable prediction with good accordance. Furthermore, the effects of some parameters such as punch diameter and depth on the punch pressure have been evaluated. [ABSTRACT FROM AUTHOR]