Draft Angle Research Articles

Enhancing the Robustness of Rib-Groove Filling and Strain Homogeneity in the Isothermal Forging of Titanium Alloy Multi-Rib Components

Isothermal forging stands as an effective technology for the production of large-scale titanium alloy multi-rib components. However, challenges have persisted, including die underfilling and strain concentration due to the complex material flow and heterogeneous deformation within the forging die cavity. While approaches centered on optimized billet designs have mitigated these challenges, uncertainties in process parameters continue to introduce unacceptable variations in forming accuracy and stability. To tackle this issue, this study introduced a multi-objective robust optimization approach for billet design, accounting for the multi-rib eigenstructure and potential uncertainties. The approach includes finite element (FE) modeling for analyzing the die-filling and strain inhomogeneity within the multi-rib eigenstructure. Furthermore, it integrated image acquisition perception and feed back technologies (IAPF) for real-time monitoring of material flow and filling sequences within die rib-grooves, validating the accuracy of the FE modeling. By incorporating dimensional parameters of the billet and uncertainty factors, including friction, draft angle, forming temperature, speed, and deviations in billet and die, quantitative analyses on the rib-groove filling and strain inhomogeneity with fluctuation were conducted. Subsequently, a dual-response surface model was developed for statistical analysis of the cavity filling and strain homogeneity. Finally, the robust optimization was processed using a non-dominated sorting genetic algorithm II (NSGA-II) and validated using the IAPF technologies. The proposed approach enables robust design enhancements for rib-groove filling and strain homogeneity in titanium alloy multi-rib components.

Optimization of forward pulsed currents for combining the precision shaping and polishing of nickel micro mould tools to reduce demoulding defects

Precise tooling is vital for defect-free production of micro injection moulded (μ-IM) or hot-embossed products. The demoulding stage of such moulding and forming processes poses a serious challenge to the integrity of thin miniature features because of friction, adhesion, and thermal stresses. Typically, micro moulds involve geometrically textured patterns or features such as linear ridges, pillars, channels, and holes, the characteristic dimensions of which range from 10 to 300 μm. Realistically complex mould designs, containing precision micro features (enhanced fillet radius and positive draft angle) and high surface quality, are presented in this work. Electropolishing based on forward pulse currents (PC) has been used to shape and polish Ni micro moulds that contain sets of micron-scaled linear ridges and star patterns in order to ease the separation of moulded polymeric parts from the metallic mould during ejection and demoulding. The use of forward pulsed currents improved the mould design by increasing the fillet radii and draft angle while keeping the surface roughness low and maintaining a good surface shine. An optimization study of forward PC using a green solution of nickel sulfamate varied EP times (0–70 min) and duty cycles (40, 50, 60, and 70%) at a process conditions of 2.8 V, 50 °C, and 250 rpm. The best topographical and morphological changes were observed for a typical microfluidic channel (w × h, 100 × 110 μm) with an EP time of 70 min and 50% duty cycle: fillet radius increased by 3.8 μm, draft angle by 3.3°, and the channel width reduced by 11.4% while surface roughness changed by 8.6% and surface shine improved by 48.9%. Experimental validation was performed using hot embossing wherein the electropolished Ni mould replicated the micro channels and star patterns in PMMA chips with notably fewer burrs, material pile up, and no feature distortion. Moreover, there was a reduction in the side wall roughness of micro channels in PDMS casting with electropolished Ni mould by 16%. Hence, this work presents a significant scientific contribution to improving the efficiency of micro mould tools and reduces the defects caused by friction and adhesion in replicated polymeric parts.

Die Design and Forging Analysis of Piston Connecting Rod of Aluminum Alloy

The piston connecting rod is an indispensable in the internal structure of the automobile. As one of the important components in the internal combustion engine system, the piston connecting rod needs to meet the requirements of high fatigue and impact load resistance. Forged piston connecting rod can obtain high strength and fatigue resistance. In this study, the parting line, draft angle, forging tolerance, die fillet radius, shrinkage and scrap are considered in the design of forging die. The process parameters and die dimensions of the forging process of aluminum alloy piston rod are simulated by finite element analysis. The aluminum alloy piston rod with high dimensional accuracy is then forged according to the finite element simulation results.

Effect of three-dimensional geometric structure and surface wettability on two-phase flow behavior in a proton exchange membrane fuel cell gas flow channel: modeling and simulation

Improving water management capability is crucial for enhancing the performance and extending the lifespan of a proton exchange membrane fuel cell (PEMFC). To achieve this goal, this study investigates the coupling effects of geometric features induced by actual gas flow channel (GFC) manufacturing processes and the surface wettability on the dynamic droplet change by simulating 32 cases using the volume of fluid (VOF) method. In addition, the simulated dynamic characteristics of the droplets, such as the centroid position and droplet height, have been verified by comparing them with experimental observations. The reliable results of the simulation show that varied draft angles contribute to different local vortices in the flow channels, arousing two drainage mechanisms—spontaneous and overflow drainage. Besides, the compared results of velocity contours suggest that the curvature effect along the water movement direction could strengthen the speed-up effect around a water droplet, thereby facilitating its detachment. By contrast, a cross-section with filleted corners could cause velocity loss and poor drainage efficiency. A geometric structure with a draft angle of 30° and a bend radius of 1 mm of wavy GFC is beneficial to shorten the water removal time and minimize gas diffusion layer (GDL) water coverage. The hydrophobic treatment of the GDL and channel wall meets both criteria of rapidly reducing liquid water coverage on both the GDL surface and the entire channel. This study's findings are expected to guide the target of both geometric manufacturing and surface treatment processes.

Effects of thermoforming operation and tooling on the thermoformability of plastic‐coated fibre‐based materials

AbstractAdvances in the three‐dimensional (3D) forming of fibre‐based materials require the formulation of more formable materials and the development of process lines, machinery, and tools. Using a thermoforming process to convert fibre‐based materials into 3D forms is an emerging area of research which requires further investigation into the practicality of the process line and tooling in forming such materials. Accordingly, this study evaluated the impact of the thermoforming process operation and tooling on the thermoformability of plastic‐coated paperboards. The main objective was to provide design recommendations for the future development of thermoforming lines, followed by guidelines for tooling design to improve the performance of materials utilising the currently available machinery. This study examined the thermoforming behaviour of two different plastic‐coated paperboards in vacuum and pressure thermoforming by investigating their maximum acquired depth, shape accuracy, and damage mechanisms. The research findings, based on the depth and linear elongation achieved, indicate that the inferior performance of plastic‐coated paperboards in thermoforming cannot be wholly attributed to restrictions in the three‐dimensional formability of materials; the inability of the current process lines to utilise the maximum potential of materials can also lead to their inferior performance. Notably, the method of pressure supply and cooling of materials requires adjustment of these materials. From a tooling perspective, owing to the spring‐back effects, the enlargement of the mould dimensions should be considered during the design stage. Additionally, based on potential opportunities with the current unmodified machinery and materials, products in the size of standard food trays have a higher likelihood of being optimised with tooling design than smaller sized shapes, which still require additional developments in materials. Moreover, designing moulds without draft angles can reduce the risk of rupture owing to the prevention of localised stress formation in materials.

Failure analysis and structural optimization for rotary mechanism of large sling based on thermal–mechanical coupling analysis

Rotary mechanism is the core part of the multi-functional sling for turning over and erecting the castings and forgings. The mechanical performance of a nail plate inside the structure determines the working safety. In this paper, the dangerous working condition of the rotary mechanism is first introduced when the castings and forgings with different diameters are clamped by the sling. Then, the temperature field and the thermal–mechanical coupling model for the nail plate are established, and the failure mode is analyzed. Next, the layout and shape of the nails on the nail plate are studied to improve the load-bearing performance. A mathematical model, taking the height and draft angle of the nail as the design variables, is established, and a new nail plate model is given. The comparison is carried out through simulation and experiment. The results show that the mechanical performances of the nail plate are significantly improved, and the failure problem of the rotary mechanism is solved.

Multi-objective crashworthiness optimization of square aluminum tubes with functionally graded BCC lattice structure filler

The objective of this study is to find the optimum design configurations for the crashworthiness of functionally graded lattice structure filled aluminum tubes under multiple impact loading conditions. Base strut diameter, draft angle and aspect ratio are considered as filler material design parameters, and the optimal design configurations are sought for maximizing the specific energy absorption and minimizing the peak crush force. The finite element simulations are performed to establish the sample design space; linear and non-linear least square regression meta-models are developed to estimate the objective function values; the weighted superposition attraction-repulsion algorithm is employed to create design alternatives and seek their optimum combinations. The compromise programming technique is also adapted for combining multiple objectives and generating different optimum design options. The results revealed that the proper selection of design parameters can effectively enhance the crashworthiness performance of hybrid structures under multiple impact loading conditions. In particular, the results showed that the specific energy absorption value of square tubes can be improved up to 76% with the selection of appropriate lattice filler parameters. The present study provides a guideline for the optimum design of functionally graded lattice structure filled thin-walled structures under multiple impact loading conditions.

The Method for Analyzing the Pitching Motion Pattern of a New Surface Unmanned Wing-sliding Boat

In this paper, a new surface unmanned wing skate (NUSV) is taken as the research object, and the free decay model test under different drafts and different initial pitch angles is completed. In the case of specially selected regular waves, typical swaying tests against waves and waves were carried out. Four mathematical models for system identification of pitch motion modes are established. Based on the system identification theory and the programming idea of the improved genetic algorithm, the NUSV pitch motion mode system identification software is written in C# language. The system identification software is developed based on experimental technology and an analysis method of ship motion patterns is developed based on the optimization theory. This paper completed the following: (1) compared and calculated the mathematical models of system identification based on four-pitch motion modes and determining their motion modes, (2) based on the results of pitch motion mode identification, the predicted values and the test results are in good agreement, which verifies the rationality of the method and the reliability of the self-compiled software, (3) analyzed the variation law of the relative value of each moment that affects the NUSV pitch decay motion with the draft and initial pitch angle, (4) analyzed the influence of the NUSV in the regular wave. The variation law of each moment of the rocking motion with the draught, wave height, and encounter period, and (5) proposed the idea of establishing a rocking motion pattern map based on the rocking test and optimal identification theory. The method and research results proposed in this paper can provide a reliable motion model for the pitch motion control of this type of boat, and provide technical support for its effective regulation of the adverse effect of the pitch on the boat’s stability. It also provides a reference for the seakeeping of this type of boat and the optimization design of the subsequent boat type. The system identification software written can also be used for system identification of the rocking motion mode of this type of unmanned boat in other directions.

Effect of Heating Temperature and Die Insert Draft Angle on the Flowability of Hot Forged SCM435 Steel

The problem of flowability in a closed forging process for heavy equipment industry is still widely found and this may affect the quality of the resulting product. To obtain the solution for this problem, in this work, the effect of heating temperature and die insert draft angle on the characteristic of hot forged SCM435 steel used for undercarriage track roller has been examined. The workpieces were heated at temperature variations of 1150 °C, 1200 °C, 1250 °C and were hot forged at die insert draft angles of 3°, 5°, and 7° to form undercarriage track roller products. The mechanical properties of the products were characterized through hardness and dimension examination, whereas the microstructure was characterized using an optical microscope. The results showed that increasing the heating temperature and die insert draft angle resulted in good flowability. The best result was obtained from the heating temperature of 1250 °C at the die insert draft angle of 7°, with diameter and height of 191.2 mm and 53.6 mm, respectively. This characteristic of the obtained hot-forged product agreed with that of the specified forging design for the undercarriage track roller

Reinforced Metal Bipolar Plate Structure with Stiffening Rib Channel for Proton Exchange Membrane Fuel Cell

Clean energy has become a concern because fossil fuels are the primary cause of climate change and air pollution. A proton exchange membrane fuel cell (PEMFC) is an environmentally friendly vehicle's alternative energy source. Bipolar plates, gaskets, gas diffusion layers, and a membrane electrode assembly (MEA) constitute a PEMFC. The bipolar plate accounts for a large portion of the fuel cell stack cost. Metallic bipolar plates are utilized in vehicle fuel cell stacks because of its low fabrication cost, high manufacturability, mechanical strength, and low weight. Despite the benefits, a thin metal plate's major drawbacks are deformation and corrosion resistance.Stamping metallic plates form trapezoidal cross-section channels, whereas machined graphite bipolar plates can form rectangular cross-section channels. These trapezoidal channels make dimensional errors such as draft angle and fillet radius. Besides, the spring back effect makes shape errors in the manufacturing process. Many kinds of research are conducted to understand the impact of channel tolerances on the performance of PEMFCs. Mainly, inhomogeneous compression in the gas diffusion layer results from channel deformation caused by unevenly distributed clamping force and shape inaccuracy of the metal bipolar plates. High contact resistance and non-uniform reactant gas distribution would result from inhomogeneous compression of GDL.A reinforced metal bipolar plate structure with a stiffening rib channel is proposed in this work to reduce bipolar plate deformation and improve gas transfer. Stiffening ribs are imprinted on the top of the channel. The geometric parameters of the stiffening ribs are shown in Fig. 1. Four geometric design parameters are selected in this study, the distance between the ribs d1, length of the rib l1, height of the rib l2, width of the rib l3. The stainless steel with a thickness of 0.1mm, 50mm×50mm active area, is used. The influence of stiffening ribs on mechanical and fluid characteristics is investigated through numerical analyses and experiments. The static structural analysis illustrated the deformation of the bipolar plates and GDL under the clamping force. The stiffening rib design improves the structure's mechanical strength, lowering bipolar plate deformation. When the endplates clamp the stack, the stiffening rib supports more stress to prevent deformation. The flow distribution in the flow field channel and GDL was then visualized using computational fluid analysis. Stiffening ribs increase the velocity of the reactant. Enhanced under rib convection makes reactant gas evenly distributed. In addition, stiffening ribs causes a convective flow beneath the rib, which improves PEMFC performance. Finally, single-cell studies proved that the modeling results are valid. Under the same operating conditions with the same geometry to the model, electrochemical reactions are investigated to decouple the leading cause of the resistances. The ohmic resistance decreases with the robust structural stiffening ribs, and the mass transport resistance decreases with the well-distributed reactants flow. Figure 1

Numerical and Experimental Investigation of the Effect of Micro Restriction Geometry on Gas Flows through a Micro Orifice

This study experimentally and numerically investigates the effects of the nozzle/needle distance (clearance) and supply pressure on single phase compressible gas flow in a micro orifice with needle restriction, which play important roles in many engineering applications such as cryogenic cooling and MEMS (microelectromechanical systems) device cooling. Nitrogen was used as the working fluid at supply pressures ranging from 10 to 50 bars, while the conical needle draft angle was 15°. The nozzle/needle distance (clearance) was changed from 100 µm to 500 µm. From the experimental point of view, the load provided by the working fluid over the needle was measured by a load sensor. For the numerical analysis, six turbulence models and three wall treatments were considered in numerical simulations. The effect of micro restriction on high-pressure micro-gas flows was further assessed by numerical modeling. It is evident from the results that the utilized turbulence model has a considerable effect on the computed results. The k–ε standard and Spalart–Allmaras models were found to be not suitable for modeling micro-scale gas flows with restriction. On the other hand, the k–ε realizable and k–ω SST models exhibit the best performance in predicting the results.

3D printing auxetic draft-angle structures towards tunable buckling complexity

With the development of 3D printing technology, auxetic structures have attracted extensive attention due to their unusual mechanical properties. In this study, we design a 3D printed auxetic structure using 2D draft angles to achieve a tunable out-of-plane double hyperbolic buckling behavior by effectively continuously varying stiffness across thickness. The influences of radii and draft angles on the buckling behaviors of the 3D printed draft-angle auxetic structures are studied by finite element method. The constitutive relationships between stress, strain, radius, and draft angle have been formulated and discussed to identify the working principle behind the mechanical performance of draft-angle auxetic structures. Finally, the buckling behavior is modelled by a laminate structure, and the accuracy of these analytical results has then been verified by experiment. This study is expected to provide a design guideline for achieving tunable buckling behavior of auxetic structures via the novel stress mismatch of draft angles and thus continuously varying stiffness along the thickness direction. The current work constitutes an initial attempt to realize the tunability of the 3D out of plane deformation of 2D plane structures under in-plane compression.

Performance analysis of a coast – OWC wave energy converter integrated system

In this paper, a cylindrical dual-chamber oscillating water column (OWC) wave energy converter semi-embedded in a coastline or breakwater is proposed. A theoretical model based on linear potential flow theory is developed to evaluate the power absorption performance of the integrated system in the finite water depth. According to the matched eigenfunction expansions, the fluid domain is divided into five sub-domains and unknown coefficients in the diffraction and radiation problems are separately solved by matching the velocity and pressure between adjacent sub-domains. A linear power take-off system considering air compressibility is adopted to connect air volume flux with the chamber pressure. The reliability of this model is assessed by general identities (i.e., far-field relations). Then the model is performed to investigate the effects of wave conditions, draft, breadth and opening angle of the chambers on the wave power extraction. It is shown that the proposed integrated system can improve the total hydrodynamic efficiency in both regular and irregular waves.

Intelligent Control Technology of Tire Tread Pattern Draft Angle for Intelligent Manufacturing

In view of the problem that the tire pattern design may not meet the production requirements, the designer needs to modify the tire pattern draft angle, and the existing pattern draft angle modification process is cumbersome, and the designer’s experience requirements are relatively high, based on the tire pattern draft angle adjustment Experience has developed a tire pattern draft angle intelligent control system for intelligent manufacturing, and developed a corresponding program based on UG10.0 based on this system. The program can automatically determine the type of pattern contour surface, can judge the contour surface unevenness based on the projection method, can automatically recommend the appropriate draft angle, and realize the rapid modification of the draft angle in batches. The actual application of the enterprise shows that this program can greatly improve the efficiency of tire pattern design.

Experimental and influencing factors of corn stalk pulling force

The harvesting of straw by the flail knife type straw cutting device will cause loose contacts between straw roots and soil, affecting the straw feed's impurity content. In this study, a theoretical analysis of the straw cutting process was conducted to explore the factors influencing the root-soil disturbance. A pulling force test device was designed to test the pulling force of the corn stalk. The response surface method was used to study the effects of various factors on the straw pulling force under different conditions of draft angles (20°, 30°, 40°), soil moisture content (15.23%, 17.62%, 20.47%), and different straw root diameters. The test results showed that the straw pulling force was directly proportional to the straw root diameter and inversely proportional to the soil moisture content. The straw pulling force decreased first and then increased with the increase of the draft angle. According to the established second-order regression model, when the draft angle was 28.5°, the soil moisture content was 20.47%, the root diameter was 22 mm, the minimum pulling force of straw was 189.635N. The test results can provide a reference for the design of straw feed harvester.

The Effect of Processing Parameters and Calcium-stearate on the Ejection Process of Injection Molded Poly(Lactic Acid) Products

We investigated the ejection/demolding of continuous production of injection molded Poly(Lactic Acid) tensile testing specimens and analyzed the effect of 1 wt% Calcium-Stearate additive as demolding agent (sliding or mold release agent) on this process. We demonstrated that the Poly(Lactic Acid) specimens could get stuck in the mold or even break during demolding during continuous injection molding in a certain type of mold, which has a low draft angle and varying cavity width along the flow path. The standard dumbbell-shaped tensile testing specimen is produced in such a mold. Demolding was rated with the use of a high-speed camera into three categories (problem-free demolding / stuck, but demolded undamaged product / stuck and damaged product). Moreover, the ejector force required to push the product out of the cavity was monitored over 30 continuous injection molding cycles. We also investigated the effect of processing parameters, such as injection rate (screw speed), holding pressure, holding time, mold temperature, melt temperature, backpressure, screw rotational speed, and pre-process drying (drying or not drying the pellets before injection molding). We managed to avoid product breakage during demolding with the proper settings of certain process parameters and the use of Calcium-Stearate, an effective demolding agent. This ensured problem-free demolding and thus continuous injection molding.

Hydroforming rules and quality control parameters analysis for metal bipolar plate

Bipolar plate is a significant component in proton exchange membrane fuel cell, which plays an important role in supporting, heat conducting, electricity conducting and transferring gas. Hydroforming is an advanced method for manufacturing metal bipolar plates. Exploring hydroforming mechanism and controlling forming quality are very important to ensure the performance of bipolar plate. In this paper, a model of a single serpentine flow filed bipolar plate in hydroforming process was established to study the hydroforming quality control mechanism. The results show that the formability and filling rate of the bipolar plates are improved by increasing the pressure in the hydroforming process. However, the partial fracture of the bipolar plates appears with pressure increases. The forming effect of die’s outer radius is better than that of inner radius, and the forming effect of bipolar plate can be improved by increasing the outer radius. The draft angle has a little effect on the formability. Increasing the width and depth will improve the filling rate, but fracture may occurs with excessive depth. With the thickness of the sheet increases, its form quality is more difficult. Those results can provide references for the bipolar plate process and parameter optimization.

Integration of design of experiment and finite element method for the study of geometrical parameters in metallic bipolar plates for PEMFCs

Bipolar plates are among the most important components of polymer electrolyte membrane fuel cells that are responsible for a high percentage of their weights and costs. Metals are a suitable replacement for thick graphite plates that require high machining costs. The present study investigates the manufacturing process of metallic bipolar plates with a thickness of 0.1 mm using the stamping process. One of the problems with the formation of metallic bipolar plates is their rupture during plastic deformation. This study is aimed to investigate the effects of the geometrical parameters of bipolar plates, including channel width, rib width, channel depth, draft angle, and corner radius, on the formation of sheets. By designing some experiments, the effect of each parameter on the thinning percentage and filling depth of the bipolar plates were evaluated. The required data is obtained using the commercial finite element code. The results show that the channel depth, draft angle, and corner radius have the most effect on the plate thinning. In addition, the corner radius and the draft angle have the highest effect on the maximum channel depth. Finally, the thinning percentage and the filling depth for other geometric parameters can be predicted by a mathematical equation.

Forging Process Analysis of 6061 Aluminum Alloy Motorcycle Brake Parts

This paper used finite element analysis of metal forming to study the forging process and die design of aluminum alloy brake parts. According to the process parameters and die design, the brake parts were forged by experiment. First, the die design is based on the product size and considering parting line, draft angle, forging tolerance, shrinkage and scrap. Secondly, the finite element analysis of metal forming is used to simulate the forging process of aluminum alloy brake parts. Finally, the aluminum alloy brake levers with dimensional accuracy and surface hardness were forged.

Introduction to the Novel Plate for Manufacturing Thermomechanical Pulp

Refiner plates for manufacturing thermomechanical pulp (TMP) exhibit heavy and blunt-bar edges because they are manufactured via casting. Thus, replacing a cast plate that has exhausted its service life is time-consuming and a large amount of energy is required to reach the target freeness. To overcome the limitations of conventional cast plates for manufacturing TMP and chemi-TMP (CTMP), new dissimilar metal-joining technology was applied to lighten the TMP plate. A lightweight aluminum alloy was used as the base of the plate, and stainless steel alloy exhibiting excellent wear resistance was used as the bars. The lightweight plate, which was manufactured by inserting the bars into the base plate, can reduce the weight of the plate by up to a quarter compared with the cast plate. The refining performance of the lightweight plate was also similar or better than those of the cast plate. Particularly, the target freeness can be reached faster because the bar edge of the lightweight plate of a vertical bar shape was sharper than those of cast bars with a draft angle. This lightweight TMP plate obtained better results than the cast plates regarding the raw material throughput, shives content, and strength property development. However, the brightness of TMP and CTMP in the lightweight plate were slightly lower compared with those in the cast plate.