Bending Operation Research Articles

GAC-ANN Technique for Prediction of Spring Back Effect in Wipe Bending Process of Sheet Metal

In manufacturing industries, sheet metal bending is a typical and key process. In sheet metal, bending is a procedure in manufacturing by the deformation in axis caused by bending operations, and furthermore, an arrangement of a few unique operations can be performed to make a difficult part. Spring back is a phenomenon that happens somewhat because of residual stress in the material, while bowing the sheet metal. In this way to accomplish the coveted curve edge and range, it is important to over twist the sheet to an exact sum. The proportion of definite curve edge to introductory twist edge is named as the spring back component. There are many components on which the spring back edge will rely on. So by optimizing every one of these variables, the coveted state of a material could be outlined. By foreseeing the spring back point, it can lower the edge by changing those parameters. Accordingly, a great forecast technique is intended to foresee the spring back point. Henceforth in this work, a forecast system is proposed in light of counterfeit neural system (ANN) with the hereditary calculation (GA) to foresee the spring back angle in sheet metal.

A Pioneering Tactic for Sustainable Waste Management: Design of a Cost-Effective Recycling Machine

In this paper we discussed the new design, fabrication and testing of a mechanical can crusher taking into deliberation the force analysis and ergonomic factors that will enable people to use this mechanical can crusher especially in Botswana rural areas. The process of crushing cans is of vital importance as it saves a percentage of space for can disposal and also makes it easier for these cans to be transported to recycling centers or landfill areas. The methods and processes used to bring this project to life include welding, cutting, bending, drilling and assembly operations. This project study is mainly about generating a new concept of a mechanical can crusher that is compact to transport from one location to another and makes can crushing easy and fascinating to the general public so as to promote people buy into crushing in Sub-Sahara market. Even though there are numerous sorts of the mechanical would crusher be able to as of now in presence, this model provides a more practical usage than previous one with the desired mechanical advantage of 10, machinability to crush the entire cans to 25% of their original size and 100% efficiency for the entire rounds.

A new flexible sheet metal forming method of incremental bending

Flexible sheet metal forming is important for many industrial sectors such as shipbuilding, chemical engineering and shell structure construction. For thin and small sheet metal, incremental forming can be used. But for thick and large sheet metal, it is not applicable. We present a new flexible sheet metal forming method of incremental bending based on minimum energy principle. In the presented method, sheet metal is formed by continuous bending operations. The minimum energy principle is used to calculate bending trajectory. In this paper multiple tools bending strategy is presented to improve forming efficiency. The presented method is tested in a customized prototype. A kind of variable curvature sheet metal has been formed. The experimental results show that the presented method is effective and efficient.

Influence of a bending operation on the bonding strength for hybrid parts made of Ti-6Al-4V

The combination of additive manufacturing and forming is a new approach for hybrid components, to connect the advantages of high productivity of forming with the individualisation of additive manufacturing. Within this work, the combination of warm bending and laser beam melting is investigated. For a suitable design of hybrid parts, the investigation of the bonding zone between the elements is essential. Therefore, the bonding strength is characterized by shear tests in consideration of stress states resulting from the bending process. To evaluate the influence of the forming process, the results are compared to unformed hybrid parts, which show a distinct influence of the stress state.

Quantitative analysis of bending fracture resistance of nanoscale Cu-buffered ZnO:Al thin films on a polymer substrate

Improving the fracture resistance of fragile inorganic thin films under various bending conditions is critical in flexible thin-film systems. Here, we introduce a Cu-buffer-layer approach to evaluate the level of enhancement in the bending fracture behavior of Al-doped ZnO (AZO) thin films on the basis of quantitative mechanical parameters such as fracture energy, film strength and fracture toughness. These fracture behaviors of thin films sputter-deposited onto polyethersulfone substrates were observed to depend largely on the thickness of the Cu buffer layer. In the case of thin films with a 20 nm-thick Cu buffer layer, crack-initiating bending strain was substantially improved from ∼1.04% to ∼1.37%; this corresponds to an improvement of ∼31.7%. The substantial improvement is attributed to the presence of the Cu buffer layer, which helps prevent the formation of cracks by absorbing crack-initiating tensile stress. The calculated values of fracture energy and film strength support well the Cu thickness dependence of fracture behavior under bending operation.

Improving Wearable Photodetector Textiles via Precise Energy Level Alignment and Plasmonic Effect

AbstractLight‐weight and ultraflexible‐fiber‐based devices that can be woven into wearable electronic products have attracted extensive attention in recent years. However, fiber‐shaped photodetectors (PDs) made from bulky metal‐wire‐based inorganic semiconductors are prone to damage with excessive bending. Therefore, this work introduces a directly constructed photodetector textile (PDT) and realizes a large‐area, organized and dense weaving of fiber‐shaped PDs for the first time. To form the structure, ZnO nanorod arrays (NRAs) are grown uniformly on the surface of Ni wire textile to fabricate an Ni‐based ZnO NRA textile, then Ag nanowires (NWs) and graphene film (outmost layer) are successively assembled on the functional textile. The precise energy level alignment of the structure is in favor of the separation and transportation of photoinduced carriers, and Ag NWs also bring about near‐filed enhancement effect on ZnO NRAs due to local surface plasmon resonances, leading to excellent device performance. The photoresponsivity under bias of 1 V is 0.27 A W−1, and the Ilight/Idark ratio calculated form the I–V curves even reaches ≈102, about two orders of magnitude larger than that of the reported fiber‐shaped PDs. Meanwhile, the whole structure also exhibits excellent durability under bending operations, which is ideal for wearable applications.

Electro-Thermal Annealing Method for Recovery of Cyclic Bending Stress in Flexible a-IGZO TFTs

Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) fabricated by low-temperature processes on a flexible substrate can easily be degraded by mechanical deformation. Furthermore, lower performance in terms of the initial characteristics and reliability levels compared to those fabricated on glass substrates with relatively high heat treatments is inevitable. To solve these problems, a local electro-thermal annealing (ETA) method was applied to flexible a-IGZO TFTs processed at low temperature to enhance the inferior initial characteristics and reliability under a bending state. The enhancement of the characteristics and reliability by ETA can be attributed to the reduction of defects related to the oxygen through a localized Joule heat treatment with an extremely short duration (~1 ms). In addition, the effectiveness of ETA to recovery from bending stress even under harsh cyclic bending operation (strain condition of 0.833%) is verified.

Evaluating shape memory behavior of polymer under deep-drawing conditions

Thermoplastic polyurethanes (TPU) are a popular family of shape memory polymers (SMP) due to their excellent abrasion & weather resistant, and mechanical strength. However, conventional processing operations or their combination with other polymers by adhesion or blending can affect their unique shape memory behavior. Currently, there are no effective methods to study and quantify the shape memory behavior of SMP based polymer laminates as they would respond to deep drawing operations. In this paper, a new method was introduced to effectively quantify the recovery behavior of TPU based polymer laminates undergoing simultaneous stretching and bending operations at different processing temperatures. The results presented show the value of developing a shape recovery characterization method that resembles the stresses of thermoforming to properly assess formability of shape memory polymers used in laminate constructions.

A novel linear ultrasonic motor with characteristic of variable mode excitation

Abstract This article presents a novel linear ultrasonic motor with two operation modes. The stator of the motor can be divided as two transducers and two isosceles triangular beams. The first bending vibration modes and first longitudinal vibration modes of the stator are superposed as two operation modes respectively, and the variable mode control is realized by a special excitation method. The operating principle of the motor and the formation of the elliptical trajectory of the driving foot are analyzed, and the variable mode excitation method is illustrated. A prototype was made and experiment investigation of the motor characteristics at different operation mode, frequency and voltage are presented and compared. Testing results of the prototype shows that this motor can gain maximum speed of 114.6 mm/s and maximum thrust force 3.33 N under bending operation mode with exciting voltage of 400 V P-P , and it can gain maximum speed of 52 mm/s and maximum thrust force 2.35 N under longitudinal operation mode with exciting voltage of 400 V P-P . The major feature of the motor is that the variable mode control can be realized by using the method of variable mode excitation and switching the operation mode to broaden the working frequency bandwidth.

Boosting Fiber-Shaped Photodetectors via "Soft" Interfaces.

Lightweight, flexible fiber-shaped devices that can be woven into wearable electronic products have received great attention in recent years. However, the bending and poor interfaces of fiber-shaped devices typically lead to ineluctable performance degradation, which is still a great challenge yet to be dealt with. Here, taking a fiber-shaped photodetector as an example, we proposed an effective strategy, constructing inorganic-organic-graphene hybrid interfaces on a single fiber, to greatly improve the performances of fiber-shaped device. In the proposed structure, the ZnO nanorod array is grown vertically on the surface of a Zn wire (center core) and then wrapped by PVK and graphene (outmost layer) as the two outer layers. These "soft" interfaces successfully built compact contacts between various functional layers even on curved interfaces, which markedly reduced the contact resistance. Meanwhile, the whole structure also exhibited excellent durability toward the bending operations. Evidently, the Ilight/Idark ratio and photoresponsivity under bias of 0.5 V are as high as 7.2 and 0.9 A/W. In particular, the photoresponse speed has been greatly improved with the rise time of 280 ms, which was 1 order of magnitude faster than that of other fiber-shaped photodetectors without the above "soft" interfaces.

Two-dimensional refractive index and birefringence profiles of a graded index bent optical fibre

Abstract A theory to recover refractive index profile of the bent graded index (GRIN) optical fibre, in core region, is proposed. This theory is applied to the bent GRIN optical fibre when it is located orthogonal in the light path of the object arm in digital holographic phase shifting interferometer; like Mach–Zehnder interferometer. In the experiment, the fibre is bent with two different bending radii and fixed on a microscope slide keeping it immersed in matching liquid. The produced phase shifted holograms, with the presence of the fibre, are recorded using an attached CCD camera. Two different processes controlling the index profile shape of the bent GRIN optical fibre are assumed. In the first process, a linear index variation is evolved from stresses in the direction of the bent radius. In the second one, there is a release of these stresses near the fibre surface, which depends on the fibre’s radius. This will affect the outer free surface of the cladding. Based on these assumptions, we are able to construct the index profile in two dimensions normal to the optical axis. We propose two functions to describe the refractive index profiles in cladding and the core regions of the bent GRIN optical fibre. The recorded phase shifted holograms are combined, reconstructed and analyzed to get the phase map of the bent GRIN optical fibre. Comparing the extracted optical phase differences with the calculated ones, a good agreement between them is found. This means that the used two dimensional proposed functions, which are describing cladding and the core indices profiles, are the most proper in this situation. Thus, we are able to determine a realistic induced birefringence profile inside the fibre which is generated by a bending operation, not only in the cladding but also in graded index core region as well.

Ultrafast Paper Thermometers Based on a Green Sensing Ink.

With the use of an ionic liquid as the ultrathermosensitive fluid, a paper thermometer is successfully developed with intrinsic ability of ultrafast response and high stability upon temperature change. The fluidic nature allows the ionic liquid to be easily deposited on paper by pen writing or inkjet printing, affording great promise for large-scale fabrication of low-cost paper sensors. Owing to the advantages of nonvolatilization, excellent continuity and deformability, the thermosensitive ink trapped within the cellulose fibers of paper matrix has no leakage or evaporation at open states, ensuring the excellent stability and repeatability of thermal sensing against arbitrary bending and folding operation. By shortening the heat exchange distance between ionic liquid and samples, it takes only 8 s for the thermometer to reach an electrical equilibrium at a given temperature. Moreover, the paper thermometer can be applied to remotely monitor temperature change with the combination of a wireless communication technology.

Springback Behavior of AA6082T6 Tubes in Three-point Bending Operation

Springback is an inevitable phenomenon in bending operations. For the geometrical accuracy in manufacturing, springback should be predicted and a required compensation should be applied to the operation. The numerical method is a very popular approach to predict the behavior of material in the operations. This method provides the reduction in time, effort and costs in comparison with the trial and error method. In this study, springback in the three-point bending operation of AA6082T6 tubes is investigated. A numerical model is established, and results are compared with experimental outputs for verification of the model. Effects of the indenter travel distance and a wall thickness of a tube in springback are studied.

Local Heat Treatment in Draw Bending for Profiles of Manganese Boron Steel 22MnB5

Due to the increasing demand for vehicles with a low fuel consumption and consequently low emissions, lightweight construction is an important task in the automotive industry. High-strength profile parts reduce the total weight of the vehicle while maintaining a high bending-resistance. Draw bending combined with inductive sheet heating and subsequent cooling represents a cost-effective and economic concept for producing partially hardened profiles for small batch sizes. This paper deals with experimental investigations to optimize and examine heating and cooling in the process chain of draw bending. After designing the process by numerical simulation, the existing draw bending machine of the IFUM was expanded by an inductive heating unit and a cooling system. Subsequently, new experiments on the implementation of a heat treatment during draw bending were carried out with this machine. In the course of these experiments, the determined process limits were recorded based on the required drawing force, the temperature courses in the process and the respective hardness values. These values served to evaluate and validate the results of the numerical simulation. By means of heating the material before it enters the forming die, it could be shown that it is possible to form super high-strength-profile components through draw bending. The material was heated up to austenitization temperature by a surface inductor and cooled by the draw bending tool and the additional air cooling. The material used was the uncoated manganese-boron steel 22MnB5. Good results with regard to process and part quality were obtained by means of an upstream heating. The comparison with the simulation also showed a high degree of similarity and consequently confirmed the results of the numerical representation of the process. Thus the general feasibility of integrating a heat-treatment into a draw bending operation was successfully proved.

Improving the formability of linear flow split profiles by laser annealing

The effect of laser annealing on the mechanical properties of severely deformed low alloy steel is discussed. Two different sets of annealing parameters were used to achieve improvements in formability. The resulting microstructures, tensile properties and hardness distributions are reviewed. Annealing at temperatures around 700 °C with very high heating and cooling rates leads to recrystallization at the surface and moderate grain growth in subsequent layers. The improvement in ductility is proven to be sufficient to prevent cracking during bending operations.

Multi response simulation and optimization of gas tungsten arc welding

In the fabrication of a pressure vessel, the successful bending operation (after welding) demands higher tensile strength of weld bead. Therefore, to achieve typical tensile strength and hardness is the primary objective of this paper. Stainless steel 304 is widely used material in almost all the industrial applications, hence it is selected as a candidate material for study of tungsten inert gas (TIG) welding process. In order to produce, a high quality and reliable welding, the welding process needs to be robust in performance. A recently developed popular experimental approach known as definitive screening design (DSD) is used for process improvement. These optimum variable settings necessary for consistent welding are obtained through the application of simulation by using central composite design. The typical values of tensile strength and hardness are obtained at a low value of purging gas flow rate, filler rod dia.; intermediate values of root gap, plate thickness; and at high values of electrode dia., current, and gas flow rate.

A novel hydroforming approach in manufacturing thin-walled elbow parts with small bending radius

Bending of a thin-walled tube with small relative bending radius is a hot topic which has aroused extensive attention in recent years. The main disadvantage of tube parts with small bending radius fabricated by available bending approaches is non-uniform wall thickness, large springback, poor fatigue performance, and wrinkle that is difficult to control for thin-walled tube bending. In order to solve this problem, a Bend-Bulge Forming (BBF) process combining rotary draw bending and hydroforming that realizes the fabricating of thin-walled elbows with small bending radius has been put forward in this study, and both FEM simulations and experiments were carried out. Meanwhile, in order to reveal the deformation behavior and the failure during BBF process, theoretical and FEM analysis were conducted by free expansion with bent tubes. The results show that the axial feeds play a prominent role in the hydroforming process. It can promote the tube wall outside of the bend contact with hydroforming die and avoid the excessive thinning. At the same time, the tube wall inside of the bend which is thickened during bending operation can be deformed sufficiently. Finally, the final parts fabricated by the BBF process have approximately constant wall thickness and high precision.

Influences on lifetime of wire ropes in traction lifts

Traction lifts are complex systems with rotating and translating moving masses, springs and dampers and several system inputs from the lifts and the users. The wire ropes are essential mechanical elements. The mechanical properties of the ropes in use depend on the rope construction, the load situation, nonlinearities and the lift dimensions. The mechanical properties are important for the proper use in lifts and the ride quality. But first of all the wire ropes (for all other suspension means as well) have to satisfy the safety relevant requirements sufficient lifetime, reliable determination of discard and sufficient and limited traction capacity. The lifetime of the wire ropes better the number of trips until rope discard depends on a lot of parameters of the rope and the rope application eg use of plastic deflection sheaves and reverse bending layouts. New challenges for rope lifetime are resulting from the more or less open D/d-ratio limits possible by certificates concerning the examination of conformity by notified bodies. This paper will highlight the basics of wire rope technology, the endurance and lifetime of wire ropes running over sheaves, and the different influences from the ropes and more and more important from the lift application parameters. Very often underestimated are the influences of transport, storage, installation and maintenance. With this background we will lead over to the calculation methods of wire rope lifetime considering the actual findings of wire rope endurance research. We'll show in this paper new and innovative facts as the influence of rope length and size factor in the lifetime formular, the reduction of lifetime caused by traction grooves, the new model for the calculation in reverse bending operations and the statistically firmed possibilities for machine roomless lifts (MRL) under very small bending conditions.

Consequences of Bend Straightening Processes on Residual Stresses and Strength of Quenched and Tempered Steels

AbstractBend straightening is a typical process step applied after heat treatment of e. g. axles and shafts. From a materials science perspective it is an elastic-plastic bending operation with a characteristic inhomogeneous deformation over the cross section of the component. Due to the local amount and distribution of plastic deformation alterations of residual stress fields result and phase transformations are possible. Consequently, bend-straightened components have inhomogeneous materials properties. In particular an anisotropy of strength exists which can be attributed to the position-dependent microstructure and sign of the residual stress state. In addition, a Bauschingereffect is possible which also has considerable impact on the deformation characteristic of the considered component. In the present paper the above mentioned aspects are demonstrated for quenched and tempered steel bars and shafts. Typical examples of residual stress states before and after straightening are presented as well as alterations of retained austenite distributions. Finally, the deformation behavior and strength of bend-straightened components is outlined and discussed.

Design and Fabrication of a Special Purpose Hydraulic Press Performing Bending Operation

Design and Fabrication of a Special Purpose Hydraulic Press Performing Bending Operation