Copper Cup Research Articles

B Flach! B Flach!

B Flach! B Flach!

Effect of geometric dimensions of forming tool on formation of wrinkles on copper cup wall during meso- and microdrawing using finite element simulation

The ratio of sheet thickness and clearances between the punch and die opening on the technological parameters are studied for the copper blank. Simulated results are verified with the experimental one.

An investigation on the size-effects on thickness-distribution of directionally rolled multi-stage deep-drawn copper cups through finite element analysis, and its validation through experimentation employed scaling law

Most sectors are moving towards downsizing products that retain high standards of quality and satisfy customer needs. Miniaturisation of components typically makes use of scaling rules. In this work, we use the idea of similarity theory to investigate the micro-and nano-scale thinning behaviours of multi-stage deep-drawn cups. Deep drawing with a limiting draw ratio (LDR) of 1.69 was used to shape ETP copper sheets into cylindrical cups via annealing and directionally rolling. Each rolling pass consists of nine incremental passes that result in a 50% reduction in thickness. The influence of scaling laws for uni and bi-directional rolling was studied, and scaled dies and punch sets were employed to create scaled cups of five different thicknesses, each 50% of the original 6 mm. For this simulation, we used Altair INSPIRE, a sort of explicit finite element analysis that uses real-world material test data. To investigate the impact of thickness variation across all scaled cups, measurements of the thickness were taken at three points on multi-stage deep-drawn cups. Bi-directional rolling produced cups with less thickness variance than uni-directional rolling. All the scaled cups had a consistency greater than the mean at the lip point and less at the cup base for both ways of rolling, it was also noticed. Physical evaluations of the drawn cups for extreme values verified that the inferred variations lie within ±15% of their original thickness for all cups, and the mean thickness likewise has 50% of its multi-stage-drawing, proving the applicability of the scaling rules.

Experimental validation of machine learning models for prediction of the thickness distribution of directionally rolled copper strips under scaling law

Predicting the results of multi-stage deep drawing in determining the thickness distribution and thinning of the workpiece are measures that will help reduce production costs by saving materials and production time. Machine Learning (ML) technique is a promising method for predicting the thickness distribution (TD) of drawn copper metal. Macro and micro products are currently used in sensitive electronic and structural applications. In this study, ML defines the relationship between the scaled thickness and the respective number of stages governed by the scaling law. It includes the development of Artificial Neural Network (ANN) tools based on machine learning to model the relationship between thickness by scaling law and stages based on multi-stage deep-drawn cups. TD is a measure of consistency. The TD is measured from the initial blank of 1500 mm long, 750 mm wide, and 6 mm thick Cu strip, reduced by 50% in nine successive steps until a final thickness of 0.1875 mm. Two ANN models used for TD prediction are Bayesian regularization (BR) and Levenberg-Marquardt (LM) algorithms. A trained machine learning model can successfully predict and verify the unseen data of 1.5 and 0.38 mm TD. ANN is used to predict the Finite Element Analysis (FEA) results and confirm them through the experimental results. The developed model can predict the TD of the multi-stage cup with the die design parameters. The difference between the TD predicted value and the measured value is based on the simulation results of multi-stage cups using the finite element method. When the predicted and measured TD, the difference in cup drawing depth is 0.5%–2.0%. The results show that the LM model is suitable for predicting the TD of formed copper cups following the scaling law.

An investigation of hybrid models FEA coupled with AHP-ELECTRE, RSM-GA, and ANN-GA into the process parameter optimization of high-quality deep-drawn cylindrical copper cups

Deep drawing is one of the primary sheet metal forming processes that is used all over the world. The current study focused on using Analytical Hierarchy Process-Elimination and Choice Translating the Reality (AHP-ELECTRE I), Response Surface Methodology-Genetic Algorithm (RSM-GA), and Artificial Neural Network-Genetic Algorithm (ANN–GA) for determining deep–drawing performance parameters. A hybrid FEA–MCDA–RSM–ANN–GA was built using an experimental design obtained from RSM to develop better quality products. It is integrated with finite element-based numerical deep drawing simulation to understand the intended responses and the impact of design factors without the need for costly trial tests. To improve the quality of drawn cups characterization, three process parameters-clearance, punch radius, and coefficient of friction-have been tuned to their optimum values like resultant tool force (N), spring back (µm), max forming limit curve (%), and max thinning rate. The optimization results showed the efficacy of the technique for process design, resulting in the reduction of both cost and time. The desirability index was calculated and compared with all the predictions. The hybrid models that have been developed may be suggested for accurate prediction and optimization of various process parameters and outcomes for any industrial application issues that could arise.

A new novel-1-step shutdown dose rate method combining benefits from the rigorous-2-step and direct-1-step methods

A new method for the calculation of Shutdown Dose Rates (SDDR) has been developed, the Novel-1-Step (N1S) method. The new method retains the benefits of only requiring a single radiation transport calculation, as in the use of the direct-1-step (D1S) method, while removing the need for pre-calculations to determine dominant nuclides and time correction factors. The N1S method uses a time dependent source and decay data for all nuclides. When reactions in the transport occur leading to unstable daughter nuclide, the correct contribution of photon radiation from all the decay products of a nuclide are calculated with no need for additional external activation calculations. Weights of these decay photons are calculated for each decay time of interest and are analytically determined based on the solutions to the Bateman equations.The N1S method has been implemented into MCNP and preliminary verification calculations performed. These calculations included the FNG ITER shutdown dose rate benchmark and the ITER SDDR cross comparison. For the FNG ITER SDDR benchmark the N1S method showed good agreement, within experimental error, for the first campaign apart from the first decay time where a C/E value of 1.34 was obtained. This overestimation was shown to be due to the decay of 64Cu inside the copper cup of the neutron generator. For the second campaign the N1S method showed an under prediction of up to 20% at short decay times and an over prediction up to 20% at longer decay times. These times are dominated by 56Mn and 58Co respectively and it is likely the difference is due to under and over predictions in the reaction rates leading to these nuclides. The ITER cross comparison showed good agreement between the N1S method and MCR2S (and by association other D1S and R2S codes). Differences seen in the results were shown to be due to difference in the calculated reaction rates using EAF2010, TENDL2019 and FENDL3.2.

White LEDs With High Optical Consistency Packaged Using 3D Ceramic Substrate

Packaging efficiency and optical performances are important indexes for white light-emitting diodes (WLEDs) packaging. In this letter, wafer-level WLEDs packaging were presented by printing phosphor on three-dimensional (3D) ceramic substrate to improve packaging efficiency and optical consistency. The 3D ceramic substrate was prepared by repeatedly electroplating copper cups on the planar direct plated copper (DPC) ceramic substrate. The phosphor concentration was adjusted to realize natural white light. The fabrication errors of the 3D ceramic substrate and the optical performances of WLED modules were analyzed to evaluate the optical consistency of the WLED modules packaged by using 3D ceramic substrate. Consequently, the fabrication errors of 3D ceramic substrate are less than 1%. When the phosphor concentration was set at 12.5 wt%, the packaged LEDs achieve a natural white light with luminous efficiency (LE) of 94.55 lm/W, correlated color temperature (CCT) of 5915 K, and chromaticity coordinate of (0.3166, 0.3345). The WLED modules exhibit small standard deviations in LE (1%), color rendering index (1%), correlated color temperature (98 K), and high reliability. The results indicate that the WLEDs packaged using 3D ceramic substrate have excellent optical consistency.

Forming Limit in the Nosing Process of Micro Copper Cups

This study used finite element simulations and experiments to investigate the forming limit in the nosing process of micro copper cups, and to establish the limit nosing curves in terms of nosing ratio, die angle, and friction factor. Two-stage processes, including backward extrusion and nosing processes, were considered in simulations and experiments at micro scale. The copper billets with 1 mm diameter and length were backwards extruded to produce the 1 mm diameter cups with 0.1 mm wall thickness. The cups were later used in the nosing processes under different forming conditions. By analysing the results of the nosed cups from the simulations, it is possible to identify the safe and failure forming conditions and establish the limit nosing curves for the nosing process. The simulation results show that the limit nosing ratio increases as the die angle or friction factor decreases. Two predicted results for poor and well lubricated conditions have been examined and are in good agreement with those from experiments. The study not only explores the characteristics of the noise process of copper cups at micro scale but also establishes the limit nosing curves which could be the guidelines for the design of micro metal components.

Comparative Formability Study of Natural Rubber, B-Nitrile Rubber and Silicon Rubber in Rubber Assisted Forming of Hemispherical Copper Cup

Comparative Formability Study of Natural Rubber, B-Nitrile Rubber and Silicon Rubber in Rubber Assisted Forming of Hemispherical Copper Cup

Study on micro nosing process assisted by ultrasonic vibration

This study used experiments to investigate the effect of ultrasonic vibration on the micro nosing process of copper cup. The billets with 1 mm diameter and length were backwards extruded to form the cups with 0.1 mm wall thickness and 1.8 mm height. The cups were then used in micro nosing processes. A forming system with the ultrasonic vibration has been developed and installed on a precision press to conduct the experiments. An optical fibre sensor and a precession load cell were equipped on the ram of the press in order to accurately measure the load and stroke of the process. Two forming conditions with and without ultrasonic vibrations of 20 kHz were considered in this study. The results show that the ultrasonic vibration can improve the materials flow which leads to an even diameter along the shrunk region of the nosed cup. Moreover, the ultrasonic vibration greatly reduces the load in the micro nosing process of the copper cup.

An improved technique for accurate heat capacity measurements on powdered samples using a commercial relaxation calorimeter

We have modified our earlier technique for accurate PPMS heat capacity measurements on powdered samples by means of applying Wakefield grease or small copper strips in the sample preparation instead of using Apiezon N high-vacuum grease. For the Wakefield grease measurements, we put a small amount of Wakefield thermal compound in a copper cup instead of potting with Apiezon N, and the accuracy of measurements on powdered benzoic acid was determined to be ±1% and ±4% in the temperature ranges of 10 K < T < 280 K and 280 K < T < 300 K, respectively. The Wakefield grease was found to improve the accuracy somewhat but overall there was no noticeable improvement in the “grease region” above T = 220 K. To overcome the known shortcomings of using Apiezon N grease above 220 K, we have replaced the Apiezon N grease with small copper strips in the sample preparation to aid thermal conductivity, which results in a less time-intensive two-step technique for the PPMS heat capacity measurement but with an accuracy, based on measurements of benzoic acid, that is ±1% from T = (10 to 300) K and, more importantly, the elimination of the “grease problem”. As an additional test of the new technique, the heat capacity of powdered bulk rutile has been measured twice within the temperature range from (2 to 300) K using the PPMS, and its standard entropy at T = 298.15 K was calculated to be (50.39 ± 0.50) and (50.31 ± 0.50) J · K −1 · mol −1, which deviates 0.08% and −0.08% from the measurement results of our low-temperature adiabatic and semi-adiabatic calorimeters, respectively. We recommend that this technique become the standard for accurate heat capacity measurements on insulating powdered samples using a PPMS system and the corresponding thermodynamic calculations.

Heat exchanger for subcooling liquid nitrogen with a regenerative cryocooler

A heat exchanger for continuously subcooling liquid nitrogen in contact with a regenerative cryocooler is analytically investigated as a next step of our recent experimental works. Since the coldhead of regenerative cryocooler has a limited surface area, a cylindrical copper cup is attached as extended surface, and a tube for liquid flow is spirally wound and brazed on the exterior surface of cylinder. Different sizes of heat exchangers are fabricated and tested with a single-stage GM cooler to cool liquid nitrogen from 78 K to 66 K. Analytical model is developed for the heat exchanger effectiveness and thermal resistance, and the results are compared with the experimental data. It is concluded that there exists an optimum for the height and diameter of cylindrical heat exchanger to maximize the cooling rate with a given unit of cryocooler.

Effects of Grain Size on Micro Backward Extrusion of Copper

This study investigates the effects of grain size on the micro backward extrusion of copper cups. An equal channel angular extrusion (ECAE) technique was applied to refine the grain size in copper. Commercial available copper was annealed, deformed by six-pass ECAE at room temperature and then heat treated to obtain a microstructure with a grain size of about 4μm. Microstructure was examined and mechanical properties including hardness and stress-strain relationship were also investigated. The processed copper was then used in a micro backward extrusion of cups with the diameter of 3 mm and the wall thickness of 0.1 mm. The extruded cups were compared with those resulting from the coppers with larger grain size prepared by different heat treated processes. This study shows that the quality of the micro extruded cup increases as the grain size decreases. By using the refine-grained coppers for the micro backward extrusion, the cups with even rim height and uniform wall thickness can be easily produced.

Ignition of Contaminated Aluminum by Impact in Liquid Oxygen—Influence of Oxygen Purity

Abstract Impact tests in liquid oxygen and oxygen enriched liquids have been conducted on aluminum foils (0.2 mm thick) used for heat exchangers of air separation units (ASUs). Some adaptations to the ASTM Standard D2512, “Standard Test Method for Compatibility of Materials with Liquid Oxygen,” have been done to ensure the good control of oxygen content in the cryogenic liquid and to get reproducible results in aluminum ignition with hydrocarbon coating. Modified striker pins with a cavity on the contact surface have been used. The vertical guiding and the centering of the striker pins have been ensured by using two machined guides. Test samples were three layers of aluminum foil, two corrugated and one flat, contaminated by various quantities of hexadecane. The criteria for the identification of aluminum ignition (positive tests) have been validated by performing Scanning electron microscope surface analysis on residuals of a few impact tests performed in copper cups. Criteria have also been defined to check that hexadecane combustion took place in negative tests. A sufficient number of tests have been performed to plot the probability of ignition of the aluminum samples as a function of the average thickness of hexadecane coating and as a function of the oxygen content in the cryogenic liquid varying from 50 % to above 99.95 %. The remaining part in the cryogenic liquid was nitrogen and 2.3 % argon except for one series of tests where the influence of the absence of argon could be identified. The results of these tests can be used to assess the risk of ignition of some aluminum exchangers or structures used in ASU.

The drawing of conical cups using an annular urethane pad

The effectiveness of the friction-actuated blank-holding technique with its three distinct variations for the drawing of cups of different shapes has now been well established. Continuing on the research with this method, presently conical copper cups have been drawn using a hollow pad. Using the measurements of strain and thickness variations on the cup wall, the quality of the cups drawn has been evaluated. Microstructural changes and hardness values along the cup wall have also been monitored. Results from the experimental investigations conducted are presented in this brief note.

The drawing of conical cups using an annular urethane pad

The effectiveness of the friction-actuated blank-holding technique with its three distinct variations for the drawing of cups of different shapes has now been well established. Continuing on the research with this method, presently conical copper cups have been drawn using a hollow pad. Using the measurements of strain and thickness variations on the cup wall, the quality of the cups drawn has been evaluated. Microstructural changes and hardness values along the cup wall have also been monitored. Results from the experimental investigations conducted are presented in this brief note.

Crystal plasticity analysis of earing in deep-drawn OFHC copper cups

The theory of thermally-activated slip is used to derive a crystal-plasticity materials constitutive model for deformation of OFHC copper single crystals. The mechanical response of the polycrystalline material is next determined from the single-crystalline materials constitutive relations using the classical Taylor approximation for apportionment of the deformation gradient between grains. Simulations of the deep drawing of cylindrical cups from as-rolled OFHC-copper blanks are next carried out using an explicit finite element formulation. The results obtained show that the crystallographic texture in as-rolled sheets, which can be accounted for through the use of crystal-plasticity, gives rise to rim-earing in fully-drawn cups. It is further shown that the extent of rim-earing can be greatly reduced by properly modifying the shape of the blank. A procedure is next proposed for optimization of the blank shape.

Shape Imperfection in Cylindrical Cups Formed by Processes of Deep- and Stretch-Drawing with Ironing.

Focusing our attention mainly on the shape quality of formed cups, the conventional cylindrical cup-drawing and the stretch-drawing processes with or without ironing are carried out. Four materials including titanium are tested. The shape quality of the products is represented by the uniformity of the wall thickness and the roundness of the cup cross-section. A new index, the distortion index, is introduced to evaluate the lack of roundness. Comparing with the cups formed by the conventional deep-drawing, the effects of the stretching and ironing on the shape quality are investigated in detail. As a rule, the stretching as well as the ironing makes the wall thickness to distribute more uniformly. Broadly speaking, the roundness of the cup is improved by the accompanied ironing with the reduction in thickness. This is not necessarily true for the stretching. However, the complete ironing does not improve the roundness of the copper cup. Typical shapes of the distorted cup cross-section are demonstrated, such as are oval, square, cross and others. For the deep- and stretch-drawing, the cup distortion pattern is related to the planar anisotropy of the tensile material properties. This is not the case for the ironing.

Single-phase induction motor with permanent magnet excitation

A permanent magnet excited single-phase induction motor (SIM) has a very simple mechanical structure. Its stator is similar to that of shaded-pole or single-phase synchronous motors. However, there are two rotors: a diametrically magnetized permanent magnet cylinder rotating freely that is mounted within a copper cup linked to the load. Field equations describing its stationary behavior are solved analytically for a simplified motor geometry. From these performance characteristics are calculated and compared with measurements. Guidelines for design optimizations are derived.

Controlled Mineralization and Assembly of Hydrolysis-Based Nanoparticles in Organic Solvents Combining Polymer Micelles and Microwave Techniques

the yield of functional circuits was limited to about 80%.More robust constructions should help to circumvent thisproblem in the future.This demonstration of fabrication of a complex, electri-cally and electrochemically functional system uses self-assembly in four ways: i) in recognition of the “lock” and“key” components, by exploiting hydrophobic interactionsbetween surfaceswith complementary shapes; ii)in tailoringthe surface properties of the subunits, by forming a hydro-philic SAM on the exposed surface of gold to prevent coat-ingwith the liquid adhesive;iii) injoining the subunits,byse-lectively forming a thin film of adhesive on the hydrophobicsurfaces by interaction of these surfaces with droplets of thisadhesive suspended in water; iv) in containing the mercurydrop as a coherent structure in the copper cup. The successof this process depends on forming the surfaces of the sub-units designed to interact into precise, complementaryshapes, and on patterning these surfaces into hydrophobicand hydrophilic regions. To achieve electrical contact repro-ducibly, some degree of mechanical freedom was required.The liquid mercury provided the system with the requiredflexibility: as long as the cathode wire of the LED touchedthe mercury,electrical contact was maintained.Simple shape complementarity, in combination with flu-idic shear and gravitational forces, has been used by Smithand co-workers in an elegant demonstration of the fillingof shaped depressions in a planar substrate by small micro-electronic devices.