Papers in JOURNAL OF THE JAPAN SOCIETY FOR TECHNOLOGY OF PLASTICITY
(vol.42 no.490 November 2001)
Mechanical Properties of Polyethylene and
Nylon-Particle-Filled Epoxy Resin
Toshio YOKOYAMA and Yoshihide HOSHINO
(Received on October 19, 2000)
Polyethylene and nylon-particle-filled epoxy resins are cured at room temperature. Then, part of them is held for two hours in a furnace at 140 and after that gradually cooled in the furnace. Nylon and polyethylene particles are 5μm and 30μm in mean diameter, respectively. The range of the volumetric ratio of filled particles is 0 to 16.7%. Tension test and bending test for the non-heat-treated and the heat-treated materials are carried out at the atmospheric temperatures of room temperature, 50 and 70. In addition, the materials are bent to an angle of 40in the working temperature range of 60 to 120, and then variations of the bent angle are measured in the atmospheric temperature range of 60 to 120. As a result, elongation of the composites is considerably increased in comparison with that of epoxy at an atmospheric temperature of 50. The tensile strength of heat-treated materials is larger than that of epoxy at an atmospheric temperature of 50. While the initial bent angle of 40is maintained up to 70 in epoxy, it is maintained up to 90 in 16.7% nylon-particle-filled epoxy resin.
Key words : material testing, tension test, bend test, bending, polymer forming, polymer composite, polymer-particle-filled epoxy, nylon particle, polyethylene particle
Formation of Thin Ring Gear with High Accuracy
by Hot Form-Rolling and Warm Finish Form-Rolling
Toshiaki TANAKA, Masatoshi SAWAMURA, Yoshinari TSUCHIYA,
Masazumi OHNISHI, Noritaka MIYAMOTO and Atsushi DANNO
(Received on December 25, 2000)
The warm finish form-rolling process was introduced after the hot form-rolling to form a thin ring helical gear with high accuracy of JIS Class No. 4. Accuracies of tooth profile, lead, single pitch error and pitch error between adjacent teeth of the hot form rolled gear were improved by two to three grades of accuracy with the finish form-rolling. High stiffness of the rolling machine, suitability of the dies indentation in the sizing operation in the hot form-rolling and a restraining of thermal distortion after warm finish rolling were effective for improving the gear accuracies of tooth space runout and the accumulated pitch error. The ring helical gears with accuracy of JIS Class No. 3 to 4 were formed by combining hot form-rolling and warm finish form-rolling under controlled blank size, heating conditions, lubrication conditions and die temperature.
Key words : hot form-rolling, gear rolling, warm finish form-rolling, helical gear, accuracy
Accuracy of Flange and Web in Simultaneous
Shrink and Stretch Flanging
\\Accuracy of Formed Product in Axisymmetric
Simultaneous Flanging of Steel Sheet I\\
Shigeo ICHIKAWA, Yasuhisa TOZAWA and Naoyuki KANETAKE
(Received on November 24, 2000)
The accuracy of a formed product in axisymmetric simultaneous shrink and stretch flanging of a cold-rolled steel sheet is investigated experimentally. The flange thickness and the residual bent height and length are slightly affected by the blank holding force and the bottoming force, and are nearly the same as those of products formed using only shrink flanging or stretch flanging. The flange angle is influenced by the distribution of the flange thickness and decreases with increasing the bottoming force when the flange is formed without the blank holding force. The web warp is reduced by increasing the blank holding force and the bottoming force. The diameter and height of the flange are not affected by the blank holding force or the bottoming force.
Key words : stretch flanging, shrink flanging, axisymmetric flanging, accuracy, steel sheet, blank holding force, bottoming force
Effects of Die Diameter and Ironing on Accuracy of
Formed Product in Simultaneous Shrink and Stretch Flanging
\\Accuracy of Formed Product in Axisymmetric
Simultaneous Flanging of Steel Sheet II\\
Shigeo ICHIKAWA, Yasuhisa TOZAWA and Naoyuki KANETAKE
(Received on December 27, 2000)
The effects of die diameter and ironing on the accuracy of a formed product in axisymmetric simultaneous shrink and stretch flanging of a cold-rolled steel sheet are investigated experimentally. The flange angle increases with increasing die diameter due to the change in the distribution of the flange thickness. The residual bent region by shrink flanging is not affected by die diameter, whereas the same region by stretch flanging is affected by it. The web warp decreases with decreasing web width. A depression mark due to unbending by bottoming remains on the narrow web when the blank holding force is weak. The accuracy of the flange that is formed is improved by ironing, leading to a more than 10% reduction in flange thickness together with a reduced residual bent height, smaller flange angle and improved diameter.
Key words : stretch flanging, shrink flanging, axisymmetric flanging, ironing, accuracy, steel sheet
Effects of Mechanical Properties of a Material and the Intensity of Impulsive
Pressure on the Edge Shape in a Punching Process of a Metal Plate
Minoru MOCHIHARA, Akio KIRA, Masahiro FUJITA,
Jun-ichiroh UENO, Kazuyuki HOKAMOTO and Yasuhiro NAKIYAMA
(Received on December 27, 2000)
The present investigation intends to clarify the effects of mechanical properties of a material and the intensity of impulsive pressure on the edge shape upon shearing in a punching process of a metal plate. The experimental results are compared with the simulated results. The analytically determined deformed shape around the edge is in good agreement with the experimentally observed shape for copper, aluminum and 304 stainless steel employed in the investigation. The results suggest that the cross-sectional shape of the hole strongly depends on the flow stress and the slope of the stress-strain curve of the material. It is also shown that the ductile-fractured area and shape of the cut edge strongly depend on the intensity of impulsive pressure.
Key words : high-energy-rate forming, punching, finite difference method, mechanical properties, shearing deformation, edge shape
Reduction of a Dent Formed at a Sheet Edge
in the Case of Tube Forming by Electric Resistance Welding
Daigo SUMIMOTO and Kenji HADA
(Received on January 9, 2001)
A dent formed at a sheet edge in the case of tube forming by eletric resistance welding spoils the accuracy of the thickness of the tube. This dent is caused by partial contact between an upper roll and a formed sheet, and the depth of the dent can be determined by a value of curvature and thickness. To reduce the dent, two-stage bending, flattening of the roll caliber and the upper roll shift to the edge side were attempted, The effect of the two-stage bending could not be made clear. However, the dent could be reduced by the flattening of the roll caliber to magnify the surface contact between the upper roll and the formed sheet.
Key words : bending, roll bending, tube forming, material testing, roll forming, ferrous metal, accuracy, plasticity theory
Shear Band Post-Bifurcation Analysis of FCC Single Crystals
\\Ductile Fracture of FCC Crystals by Shear Band Formation II\\
Shokichi KANNO, Akinori SATO, Jun NITTA,
Koichi ITO, Yoshihiro KAMADA and Taketoshi SAGAWA
(Received on January 9, 2000)
A numerical analysis, based on crystal plasticity, of the formation and the propagation of localized shear bands in ductile single crystals is carried out in order to establish a fundamental basis for predicting the forming limit of sheet metals. The critical state of shear band formation and the direction of the shear band of each element are predicted by the bifurcation theory. For the post-bifurcation analysis, a hypothetical 13th
slip system is introduced into the elements that satisfy the bifurcation conditions. Results of numerical analysis of plane strain compression reveal that an envelope line connecting the shear band directions of elements penetrates the metal layer. We define the moment of shear band penetration as the stage of metal fracture. The experimental results of single crystals under the plane strain compression also suggest that shear bands are closely related to metal ductile fracture.
Key words : numerical analysis, sheet metal forming, shear band, post-bifurcation analysis, hypothetical slip system, crystal plasticity
Influence of Die-Wall Friction and Internal Energy Dissipation
on Final Mean Density in Multilayer Powder Compaction
\\Multishock Compaction of a Copper Powder
Medium in a Die by Punch Impact VII\\
Koji TOKUSHIMA, Yukio SANO and Akihisa ABE
(Received on January 26, 2001)
For the compaction of copper powder media of 2-12 layers impacted by a punch with velocities of 20, 35, and 50 m/s, where lower (L) and higher (H) initial densities are arranged alternately, the influences of die-wall friction, internal energy dissipation, separation-reimpingement of the punch and medium on the final mean density are examined. The influence of die-wall friction is the most conspicuous. It has less effect in the L-H-type arrangement where an L layer is impacted by a punch than in the H-L-type arrangement for a given number of layers, because energy loss due to wall friction is smaller in the former. The influence of the energy dissipation and separation-reimpingement is negligibly small.
Key words : dynamic compaction, powder, multilayer, shock wave, die-wall friction, internal energy, dissipation, theoretical analysis, pseudo-viscosity method, green density
Application of Simulation of the Nonsteady State
for Aluminum Rectangular Extruded Pipes
Toshiyuki INAGAKI, Satoshi MURAKAMI, Norio TAKATSUJI,
Kenji MATSUKI, Mitsuyuki ISOGAI and Jun SYOBO
(Received on January 29, 2001)
It is known that computer technology has rapidly advanced in recent years, and it is useful for application to various simulations. In case of aluminum extrusion, there are many reports on simulation by fluid dynamics or large deformation, but almost of them have been applied in the field of steady metal flow conditions with solid die extrusion in general, and there are few reports on the nonsteady metal flow condition with hollow die extrusion. In this study, the simulation technology for the nonsteady metal flow condition of hollow die extrusion is applied, and the effects of porthole shape on the extrusion pressure-stroke diagrams and the metal flows are investigated experimentally and theoretically.
Key words : extrusion, simulation, non-steady metal flow condition, porthole shape, pressure-storke diagram