Design and manufacturing of an innovative rolling ball tool: A step forward towards the development of SPIF process

Incremental sheet forming (ISF) is an innovative forming technology which is widely used in various sectors of mechanical production. This is particularly useful for rapid prototyping and limited batch without a specific die. A new class of this method is single-point incremental forming (SPIF). This paper presents a comprehensive experimental investigation on the SPIF of Aluminum sheets, and, in particular, the influence of the forming tool is taken into account. A new rolling ball tool is designed to follow this, and the formability of the Aluminum sheets under the SPIF procedure is investigated for both new and conventional tools. Moreover, a number of important process parameters such as the feed rate, forming force, and surface roughness are considered in the experiments’ design. Finally, the optimal conditions in achieving a developed SPIF procedure in terms of the mentioned factors are reported and discussed. The findings of this work suggest that the surface quality after the forming process can be enhanced by 55% when using the new designed tool, while the forming force is reduced by 38% at the same time.

Comparative Analysis of Machine Learning Methods for Predicting Robotized Incremental Metal Sheet Forming Force

This paper proposes a method for extracting information from the parameters of a single point incremental forming (SPIF) process. The measurement of the forming force using this technology helps to avoid failures, identify optimal processes, and to implement routine control. Since forming forces are also dependent on the friction between the tool and the sheet metal, an innovative solution has been proposed to actively control the friction forces by modulating the vibrations that replace the environmentally unfriendly lubrication of contact surfaces. This study focuses on the influence of mechanical properties, process parameters and sheet thickness on the maximum forming force. Artificial Neural Network (ANN) and different machine learning (ML) algorithms have been applied to develop an efficient force prediction model. The predicted forces agreed reasonably well with the experimental results. Assuming that the variability of each input function is characterized by a normal distribution, sampling data were generated. The applicability of the models in an industrial environment is due to their relatively high performance and the ability to balance model bias and variance. The results indicate that ANN and Gaussian process regression (GPR) have been identified as the most efficient methods for developing forming force prediction models.

A Novel Force Variation Fine Blanking Process for the High-strength and Low-plasticity Material

Fine blanking is a kind of metal forming process with the advantages of high precision, good surface quality and low cost. Influenced by the concept of lightweight, a large number of metal materials with high strength are widely used in various fields. High strength materials are prone to be cracked during plastic deformation due to their poor plasticity, which limits the application range of them. This paper proposed a force variation fine blanking process for high-strength and low-plasticity materials. At the same time, a method to find the curve of forming force for this novel process was presented. A 2D finite element fine blanking model was established for the TC4 material. Combining genetic algorithm and neural network methods, a model was built up to find the optimal forming force loading curve. The parts fabricated by force variation loading and constant loading fine blanking process were compared through experiments. The mechanism of force variation fine blanking is also revealed. The forming force mainly affects the length of clean cutting surface by affecting hydrostatic stress. According to the ultimate optimal loading curve, the forming force should be kept at a low level in the early stage of blanking stroke, and increased gradually in the ending stage. In the application of force variation fine blanking, the part with long length of clean cutting surface can be obtained with lower die load.

Modeling and Analysis of Multi-pass Progressive Flanging Force of Round Metal Tubes

Pipe flanging is needed extensively in the industrial field, and its technological requirements are complicated and changeable. Currently the special flanging die and equipment are less flexible, while the whole set of equipment cost is high. As a result, pipe flanging technology with strong adaptability is necessary in single-piece or small-batch production. In this paper, a multi-pass progressive flanging process of round metal pipes with ball-end tool bar as forming tool is introduced, and dieless flanging of pipe can be realized by means of numerical control machine. In the dieless flanging process, the feedback and control of flanging force is a key factor for the flanging quality to meet design requirements. Therefore, this paper studies the change of flanging force in the multi-pass progressive flanging process of round metal tubes by combining theory, simulation and experiments. Based on the process of multi-pass progressive flanging of round pipes, an analytical model of the forming force of multi-pass progressive flanging of round pipes is established by taking the micro-element contacting tool bar with pipe as the research object. With the commercial ABAQUS finite element software, the multi-pass progressive flanging process of round pipes is simulated, and the evolution data of stress and strain field of the pipe during flanging process are obtained. Finally, a multi-pass progressive flanging test system is set up, and the three-dimensional forming force on the tool bar in flanging is measured. The flanging force measured by analytical calculation, finite element simulation and experiment is in good agreement. When the flanging angle is small, the radial forming force is the largest, followed by the axial forming force. As the flanging angle increases, the difference between radial forming force and axial forming force decreases gradually. When the flanging angle is greater than 30 to 40 degrees, the axial forming force becomes the largest, followed by the radial forming force.

Static Strength Analysis and Experimental Research of Clinched Joints By Two-strokes Flattening Clinching Method

Clinching technology is widely used to join sheet materials in manufacturing fields, especially in automotive lightweight applications. However, the clinched joints have a weak static strength and high protuberance, which influence the application of the clinching technology. In order to improve the static strength and decrease the protuberance height of clinched joint, a new method to join aluminum alloy sheet materials with two-strokes flattening clinching (TFC) was investigated in this paper. The tension-shear strength, cross-tension strength, energy absorption and failure modes of clinched joint and TFC joint were investigated. Furthermore, the stiffness and the hardening exponent of the joints under different experimental tests were studied. The results indicated that the mechanical behaviors of the joints were optimal when the forming force was 35 kN. The maximum cross-tension and tension-shear strength of TFC joint were increased by 514 N and 1145 N on average compared with the initial clinched joint. The main failure modes of the joints were the neck fracture mode under the tension-shearing and cross-tension test. In addition, the stiffness and hardening exponent explained the variation of the mechanical properties of the joints under different forming forces.

Central Composite Design Optimisation in Single Point Incremental Forming of Truncated Cones from Commercially Pure Titanium Grade 2 Sheet Metals

Single point incremental forming (SPIF) is an emerging process that is well-known to be suited for fabrication in small series production. The aim of this paper was to determine the optimal input parameters of the process in order to minimise the maximum of both the axial and the in-plane components of the forming force achieved during SPIF and the surface roughness of the internal surface of truncated-cone drawpieces. Grade 2 pure titanium sheets with a thickness of 0.4 mm were used as the test material. The central composite design and response surface method was used to determine the number of experiments required to study the responses through building a second-order quadratic model. Two directions of rotation of the forming tool were also considered. The input parameters were spindle speed, tool feed rate, and step size. The mathematical relations were defined using the response surfaces to predict the surface roughness of the drawpieces and the components of the forming force. It was found that feed rate has an insignificant role in both axial and in-plane forming forces, but step size is a major factor affecting axial and radial forming forces. However, step size directly affects the surface roughness on the inner surfaces of the drawpieces. Overall, the spindle speed −579 rpm (clockwise direction), tool feed 2000 mm/min, and step size 0.5 mm assure a minimisation of both force components and the surface roughness of drawpieces.

A Study on the Effects of Temperature, Punch Radius and Punch Stroke on Forming Force When Bending SS400 Steel Plate

Sheet metal forming process is a basic deformation method in the mechanical field. In particular, bending deformation processing is a universal processing method which is widely used to form sheet metal parts such as aviation industry, shipbuilding, automotive and so on. During sheet metal bending process, the forming force is a very important output parameter that needs to be determined to ensure the load capacity of a machining equipment. This forming force magnitude will vary according to machining conditions, Geometric shapes of products, sheet materials, etc. This study examines the influence of technological and geometric parameters such as: work-piece temperature, punch speed and sheet thickness to bending force when forming V-shape of SS400 sheet material.

Thin Ice: Teasing Play as a Network-Forming Force in Organizations

Play is a deeply human constitutive activity of organizational life, which may manifest in several distinct processes. In the present study, the author compasses a particular culturally relative form of play, namely teasing in the workplace setting. Conducting a meta-synthesis of adjacent streams of literature, the author reframes the concept of teasing and inspects it through the analytical lens of play. The research unfolds how teasing behaviour may form an invisible meta-network in organizations, which may fundamentally affect group and organizational dynamics.