Pulsewise-Motion Controlled Stamping for Microtexturing Onto Aluminum Sheet

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Tatsuya Fukuda
Keyword(s):  
Pure Aluminum ◽  
Metal Flow ◽  
Numerical Control ◽  
Aluminum Sheet ◽  
Normal Loading ◽  
Precise Control ◽  
Dlc Coating ◽  
Diamondlike Carbon ◽  
Oxygen Plasma Etching ◽  
Loading And Unloading

High density oxygen plasma-etching was applied to microtexturing onto the diamondlike carbon (DLC) films coated on the die-unit substrates. This mold-die unit with microtextured DLC coating was fixed into a cassette die for computer numerical control (CNC) stamping with the use of precise control both in loading and feeding the sheet materials. In particular, the pulsewise-motion control in stamping was employed to describe the effect of loading and unloading subsequences in the incremental motion on the microtexturing with reference to the normal loading motion. The macroscopic plastic deformation as well as the microscopic metal flow were studied to prove that the pulsewise-motion should be responsible for homogeneous duplication of microcavity patterns into a pure aluminum sheet with high aspect ratio.

Effects of Punch Cross-Section on Deep-Drawability of Square Shell of Aluminum Sheet

1987 ◽  
Vol 109 (4) ◽  
pp. 355-361 ◽  
Author(s):  
N. Kawai ◽  
T. Mori ◽  
H. Hayashi ◽  
F. Kondoh
Keyword(s):  
Crack Initiation ◽  
Cross Section ◽  
Pure Aluminum ◽  
Metal Flow ◽  
Aluminum Sheet ◽  
Forming Limit ◽  
Planar Anisotropy ◽  
Deep Drawability ◽  
Commercially Pure ◽  
Relief Effect

Effects of product shape and a planar-anisotropy on a square shell drawability were studied, using commercially pure aluminum sheet. Two phenomena were mainly considered to affect a forming limit: (a) the prevention of crack initiation at the corner of a punch by adjacent straight punch profile regions, (b) the metal flow in the flange region from the corner to the straight side, the “Strain Relief Effect,” which serves to decrease the deformation at the corner.

Motion-Controlled Precise Stamping for Microtexturing onto Aluminum Sheet

2014 ◽  
Vol 622-623 ◽  
pp. 64-71 ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Taichi Itoh ◽  
Masahiro Tamaki ◽  
Tatsuya Fukuda
Keyword(s):  
Motion Control ◽  
Metal Flow ◽  
Constant Load ◽  
Aluminum Sheet ◽  
Heat Radiation ◽  
Geometric Accuracy ◽  
Micro Pattern ◽  
Die Set ◽  
Oxygen Plasma Etching ◽  
Micro Patterns

Mass production of heat radiation devices requires for fine stamping of micro-textured patterns in the order of micro-meters in dimension onto the sheet product. In this duplication of micro-textured patterns, an original mother micro-pattern in the convex type has to be transferred onto the metallic sheet in the concave type with sufficient accuracy. The authors have proposed a micro texturing of original micro patterns onto the DLC coated mother die-and mold-unit. Once this unit is inserted and fixed in the stiff cassette die-set, the CNC-controlled stamping system works well for progressive stamping process to duplicate the original micro-patterns onto aluminum sheet. In the present paper, two kinds of motion in the stamper were designed to investigate the effect of loading and unloading sequences on the geometric accuracy in micro-texturing. Both the macroscopic and microscopic plastic deformations were described by SEM observation. First, high density oxygen plasma etching method was introduced to explain how to fabricate the micro-textured DLC-die unit. The constant-load motion control was employed as a normal motion in CNC-stamping to describe the microscopic metal flow by piercing the DLC micro-punch into the aluminum sheet. Deep micro-cavities with 3.5x3.5x3 μm3were successfully formed by application of high pressure in stamping. The pulse-wise motion control was further used to improve the geometric accuracy in the present duplication of original micro-texturing pattern onto the aluminum sheet. Owing to the incremental loading in this motion control, the micro-friction was significantly reduced to activate the microscopic metal flow in formation of micro-cavities.

scholarly journals The Chosen Aspects of Skew Rolling of Hollow Stepped Shafts

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 764
Author(s):  
Jarosław Bartnicki ◽  
Yingxiang Xia ◽  
Xuedao Shu
Keyword(s):  
Cross Section ◽  
Rolling Mill ◽  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Numerical Control ◽  
Technological Parameters ◽  
Flow Mechanisms ◽  
The Individual ◽  
Skew Rolling

The paper presents chosen aspects of the skew rolling process of hollow stepped products with the use of a skew rolling mill designed and manufactured at the Lublin University of Technology. This machine is characterized by the numerical control of spacing between the working rolls and the sequence of the gripper axial movement, which allows for the individual programming of the obtained shapes of parts such as stepped axles and shafts. The length of these zones and the values of possibly realizable cross-section reduction and obtained outlines are the subject of this research paper. The chosen results regarding the influence of the technological parameters used on the course of the process are shown in the present study. Numerical modelling using the finite element method in Simufact Forming, as well as the results of experimental tests performed in a skew rolling mill, were applied in the conducted research. The work takes into account the influence of cross-section reduction of the hollow parts and the feed rate per rotation on the metal flow mechanisms in the skew rolling process. The presented results concern the obtained dimensional deviations and changes in the wall thickness determining the proper choice of technological parameters for hollow parts formed by the skew rolling method. Knowledge about the cause of the occurrence of these limitations is very important for the development of this technology and the choice of the process parameters.

Evaluation of DLC Coatings for High-Temperature Foil Bearing Applications

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Said Jahanmir ◽  
Hooshang Heshmat ◽  
Crystal Heshmat
Keyword(s):  
Carbon Film ◽  
Dlc Coatings ◽  
Foil Bearings ◽  
Dlc Coating ◽  
Foil Bearing ◽  
Flat Disk ◽  
Wide Range ◽  
Diamondlike Carbon ◽  
Powder Lubrication ◽  
Foil Thrust Bearing

Diamondlike carbon (DLC) coatings, particularly in the hydrogenated form, provide extremely low coefficients of friction in concentrated contacts. The objective of this investigation was to evaluate the performance of DLC coatings for potential application in foil bearings. Since in some applications the bearings experience a wide range of temperatures, tribological tests were performed using a single foil thrust bearing in contact with a rotating flat disk up to 500°C. The coatings deposited on the disks consisted of a hydrogenated diamondlike carbon film (H-DLC), a nonhydrogenated DLC, and a thin dense chrome deposited by the Electrolyzing™ process. The top foil pads were coated with a tungsten disulfide based solid lubricant (Korolon™ 900). All three disk coatings provided excellent performance at room temperature. However, the H-DLC coating proved to be unacceptable at 300°C due to lack of hydrodynamic lift, albeit the very low coefficient of friction when the foil pad and the disk were in contact during stop-start cycles. This phenomenon is explained by considering the effect of atmospheric moisture on the tribological behavior of H-DLC and using the quasihydrodynamic theory of powder lubrication.

Condensation performance of superhydrophobic aluminium surface material used for cooled ceiling panels under highly humid indoor conditions

2021 ◽  
Vol 2069 (1) ◽  
pp. 012121
Author(s):  
Z W Zhong ◽  
J L Niu ◽  
W Ma ◽  
S H Yao ◽  
M Yang ◽  
...  
Keyword(s):  
Superhydrophobic Surface ◽  
Pure Aluminum ◽  
Dew Point ◽  
Aluminum Sheet ◽  
Measured Temperature ◽  
Pure Aluminium ◽  
Radiant Cooling ◽  
Long Time ◽  
Cooled Ceiling ◽  
Indoor Conditions

Abstract The application of radiant cooling systems is very limited in hot and humid areas due to condensation. Research on superhydrophobic surface (SHS) materials has shown the potential of restricting the size of condensate drops on these materials, which provides possibilities for preventing dripping and thereby alleviating condensation risks for cooled ceiling panels, but there are few studies on the anti-condensation performance of these materials under the scale and conditions of building applications. An experimental study of condensation on superhydrophobic materials under indoor conditions is presented in this article. Two material samples with a size of 2.5 cm, including a superhydrophobic aluminum sheet and a pure aluminium sheet, were affixed on a cooled ceiling panel to perform the experiment under the following condition: temperature is 25°C ± 0.5°C, relative humidity is 80% ± 5%, and air dew point is 21.4°C. The panel was cooled by chilled water of 6°C for eight hours. The measured temperature on sample surfaces was about 13.5°C during the experiment. After eight-hour condensation, the diameter of drops on the superhydrophobic aluminum sheet was less than 150 μm, while the max drop on the pure aluminum sheet was near 4 mm. The results suggested that the size of condensate drops on superhydrophobic surface materials can be largely restricted during a long-time indoor operation below the dew point, which shows their potential for constructing condensation-free radiant cooling panels.

Boss Forming, An Environment-Friendly Rotary Forming

2007 ◽  
Vol 344 ◽  
pp. 947-953 ◽  
Author(s):  
K. Kawai ◽  
H. Koyama ◽  
T. Kamei ◽  
W. Kim
Keyword(s):  
Experimental Study ◽  
Circular Plate ◽  
Working Conditions ◽  
Room Temperature ◽  
Pure Aluminum ◽  
Metal Flow ◽  
Forming Process ◽  
Environment Friendly ◽  
Commercially Pure ◽  
Technological Possibility

Boss forming, which is sometimes called hub forming, has attracted its attention as an environment-friendly rotary forming process to form a circular plate with a hole into a boss shape. An experimental study was conducted to survey the technological possibility of boss forming. Boss forming of A1050-O commercially pure aluminum plate of 10 mm thickness was carried out at room temperature under various working conditions. The effects of the working conditions on the metal flow in boss forming were clarified experimentally.

scholarly journals Crystallographic Orientation Distribution Control by Means of Continuous Cyclic Bending in a Pure Aluminum Sheet

2007 ◽  
Vol 48 (8) ◽  
pp. 1992-1997 ◽  
Author(s):  
Yoshimasa Takayama ◽  
Yuji Uchiyama ◽  
Tsuyoshi Arakawa ◽  
Masakazu Kobayashi ◽  
Hajime Kato
Keyword(s):  
Crystallographic Orientation ◽  
Pure Aluminum ◽  
Orientation Distribution ◽  
Aluminum Sheet ◽  
Cyclic Bending

Fracture toughness of diamondlike carbon coatings

1999 ◽  
Vol 14 (5) ◽  
pp. 2173-2180 ◽  
Author(s):  
M. Nastasi ◽  
P. Kodali ◽  
K. C. Walter ◽  
J. D. Embury ◽  
R. Raj ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Total Work ◽  
Carbon Coatings ◽  
Dlc Coatings ◽  
Si Substrates ◽  
Dlc Coating ◽  
Diamondlike Carbon ◽  
Radial Cracks ◽  
Work Of Fracture

The fracture behavior of diamondlike carbon (DLC) coatings on Si substrates has been examined using microindentation. The presence of DLC coatings reduces the radial crack length to less than one-half the crack length observed in uncoated Si at the same indenter load. A total work of fracture analysis of the radial cracks formed in the DLC-coating/Si-substrate system gives 10.1 MPa m1/2 as the average fracture toughness for DLC alone. A bond-breaking calculation for DLC suggests that the elastic limit fracture toughness should be 1.5 MPa (m)1/2. The higher value obtained from experiment and total work analysis suggests that plastic work and/or a tortuous path crack evolution occurred during DLC fracture process.

Improved adhesion of diamondlike coatings using shallow carbon implantation

2000 ◽  
Vol 15 (3) ◽  
pp. 590-592 ◽  
Author(s):  
Gerard W. Malaczynski ◽  
Alaa A. Elmoursi ◽  
Chi H. Leung ◽  
Aboud H. Hamdi ◽  
Albert B. Campbell
Keyword(s):  
Silicon Content ◽  
Carbon Matrix ◽  
Metal Carbides ◽  
Cohesion Strength ◽  
Subsequent Growth ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Diamondlike Carbon ◽  
Plasma Immersion Ion Implantation ◽  
Implantation Profile

A surface layer of metal carbides provides an excellent interface to achieve a highly adherent diamondlike carbon (DLC) coating. A plasma immersion ion implantation (PIII)-based procedure is described, which delivers a high retained dose of implanted carbon at the surface of aluminum alloys. A shallow implantation profile, followed by argon sputter cleaning and continued until a saturated carbon matrix is brought to the surface, provides an excellent interface for subsequent growth of DLC. At a carbon retained dose above 1018 atoms/cm2 the DLC adhesion exceeds the coating's cohesion strength. Regardless of the silicon content in the aluminum, the coating produced by this method required tensile strengths typically exceeding 140 MPa to separate an epoxy-coated stud from the coating in a standard pull test. Improved DLC adhesion was also observed on chromium and titanium. The reported tensile strength is believed to substantially exceed performance of DLC coatings produced by any other method.

Sign in / Sign up

Export Citation Format

Share Document