Papers in JOURNAL OF THE JAPAN SOCIETY FOR TECHNOLOGY OF PLASTICITY
(Vol.37 No.422 March 1996)
Effect of Rolling Lubricant Viscosity on Lubrication Mechanism
in Cold Rolling of Steels
Hiroyasu YAMAMOTO, Toshimasa TOMOKIYO, Shoichi ARAYA,
Tsuyoshi INOUE and Kazuo WATANABE
(Received on November 1. 1994)
Two-pass cold rolling experiments with stainless steel sheets (SUS430) and rolling
lubricants of different viscosities are performed to show the effect of rolling lubricant
viscosity on friction coefficient, ratio of contact area and surface roughness of rolled
sheets.
Also, the thickness of lubrication film induced into a roll bite and the friction
coefficient of boundary lubrication are calculated using a numerical analysis model
of cold rolling lubrication and the rolling experiment data.
Then, the formation mechanism
of surface roughness of rolled sheets and the variation mechanism of friction
coefficient in cold rolling are discussed from the viewpoint of the viscosity of rolling
lubricants.
Key words : cold rolling, stainless steel, friction coefficient, surface roughness, ratio
of contact area, lubrication, lubricant, viscosity, numerical analysis.
Flexible Forming Technique for Heat Exchangers
Using Uniform Moment Bending Method
- Dieless Forming Technique for Double Layered Heat Exchangers I -
Toshiyuki AMIMOTO, Takashi ISHIGAMI, Hiroya MURAKAMI,
Mitsuru KURAGANO, Motoya TANIGUCHI and Takeshi KAWANA
(Received on February 3, 1995)
Recently, consumers' needs for packaged air conditioners with high quality, energy savings, and low price
are rising for use in of office and shops. A heat exchanger, which is the principal component of air conditioners, is
composed of copper pipes and aluminum fins and is formed into square shapes. This component requires
production rationalization in order to manufacture a competitive, lightweight, and easy-to-assemble air conditioner.
To correspond to design changes for multigeneration use and to achieve defectless forming, a dieless forming
technique was developed. This is called the uniform moment bending method (UMB method) which loads a
uniform bending moment without any shearing force on the portion of the workpiece to be bent. Using this
method, double-layered heat exchangers can be formed simultaneously with variable bending radii, which can
reduce the number of assembly processes. Product defects such as fin damage can also be reduced because there is
no physical contact against a die. Double-layered heat exchangers can be made with formed angle of 89.0 degree - 91.0 degree
and pipe flatness of 3.3 +/- 1.6%, which enables them to be mass-produced.
Key words : die bending, dieless bending, bending moment, plastic theory, bending machine
Fabrication of a Diamond-Coated Drawing Die and Performance Test
Masao MURAKAWA, Sadao TAKEUCHI and Kazunari YOSHIDA
(Received on April 26, 1995)
This study has shown that a diamond-coated drawing die can be fabricated by the conventional
hot-filament CVD method in which the shape of the filament is optimized so as to yield a
uniform diamond thickness over the die surface. The deposition conditions have also been
optimized to cause compressive stress in the coating film on a WC substrate of which the
fabricated drawing die is made. A fundamental drawing test using copper and steel wires has
shown that the fabricated die can produce a drawn surface for copper wire as excellent as
that produced by a sintered diamond die. For steel wire, it has been rather surprisingly
shown that the die can withstand the high drawing stress. To understand this result, we
first discuss the deformation of die substrate using a FEM analysis. Finally, based on the
results of measuring residual stress in the film with an X-ray analyzer, we discuss the
effect of residual stresses on the reinforcement of the diamond film.
Key words : drawing, tool design, CVD diamond. coated die. diamond coating. residual stress,
PEM analysis
Production of Al-Si Alloy Strips by Means of Melt Direct Rolling
Yoshihiro SAITO, Nobuhiro TSUJI,
Kazuyasu ADACHI and Masaya OKADA
(Received on May 29, 1995)
Al-Si cast alloy strips have been successfully direct-rolled from the molten state using a rolling mill with a
closed pass 40mm wide. Surface defects appear when Si content exceeds 12(~0 or the roll speed exceeds a critical
value. The direct-rolled strips show mechanical properties (tensile strength and elongation) superior to those of
the cast strip. This is because the direct-rolled strips have fine microstructures without defects due to rapid
solidification and a large amount of rolling reduction. Distribution of Si concentration is inhomogeneous through
the thickness of the hypoeutectic Al-Si direct-rolled strips. presumably because of squeezing of the Si-enriched
melt.
Key words : melt direct rolling. non-ferrous metal (Al-Si), strip casting, near net shape process, mechanical
property, segregation, microstructure, surface defect
Method for Calculating Blank Shapes for Irregularly Shaped Cylindrical Shells
with an Arbitrarily Shaped Flange
Toshihiko KUWABARA, Wen-hua SI and Masayuki SHUUNO
(Received on June 5, 1995)
A method for determining optimum blank shapes used in the production of irregularly shaped cylindrical
shells with an arbitrarily shaped flange is proposed. All of the procedures for calculation are incorporated into a
CAD system that can output the blank shape in a few seconds using a personal computer. This calculation
method is also applicable to other irregularly shaped shells, such as L-shaped shells and oil-pan-shaped shells.
The calculation method is based on the slip-line field theory; a kinematically admissible velocity field for the
flange region is determined from the theory and the calculated velocity field is used to conduct a backward
calculation of the metal flow, from the predetermined flange shape to the initial blank shape. In the calculation it
is assumed that the material is isotropic and that the thickness of the blank remains constant during the deep-
drawing process. A deep-drawing experiment is conducted for a square shell with six different flange shapes,
using aluminum alloy sheet A5182-O 1.0mm thick and cold rolled steel sheet SPCE 0.5mm thick. Experimental
flange shapes are in good agreement with the designed (predetermined) ones. The influence of material
characteristics on the blank design is found to be relatively small.
Key words : sheet metal forming, deep drawing. cylindrical shell, flange shape, blank design, slip-line field theory,
CAD
Effect of Si Content on Surfacial Quality of Extruded Al-Mg2Si Alloys
Toshihiro TAKAI, Mitsugu TOKIZAWA, Norio TAKATSUJI,
Kazuo MUROTANl, Kenji MATSUKI and Hiroyuki MORITA
(Received on June 12, 1995)
The effect of Si content in Al-Mg2Si alloys on the reduction of a die-line defect on the
extruded production surface is investigated experimentally. A divided die is used in order to
directly observe the correspondence of the bearing surface to the extruded sample surface. The
bearing surface is polished to a mirrorlike finish by buffing so that the effect of chemical
composition of the alloy lay be clearly observed. The extruded samples of Al-Mg2Si alloys with
Si content ranging from 0.23 to 0.43wt% have bright smooth surface and nonbright rough
surface. The extruded samples of Al-Mg2Si alloys with Si content ranging from 0.53 to
0.73,wt% have surface of high quality with uniform surface roughness. It is confirmed that
the adhesion on the bearing surface in case of extrusion of the sample with uniform surface
roughness is thick and the adhesion lakes the bearing surface rough.
Key words : direct extrusion, non-ferrous metal (Al-Mg2Si), divided die, surface roughness.
Blow Forming of Superplastic Alloy Sheets by Gas Generating Source
Hiroaki OHSAWA and Satoshi FURIHATA
(Received on June 19, 1995)
Superplastic forming(SPF) of titanium and aluminum alloy sheet and concurrent superplastic
forming I diffusion bonding (SPF/DB) of titanium alloys have developed to a state of relative
maturity over the past twenty years. However SPF/DB is currently limited to titanium alloys:
an effective way to diffusion-bond aluminum alloys has not yet been developed because of a
firm and hard aluminum oxide layer on the surface. On the other hand it is well known that
if the reduction ratio, for instance in manufacturing clad metal sheets. is high enough that
strong bonding on the interface can he achieved. roll bonding between similar I dissimilar
metals can he successfully carried out. In this rolling process, if any geometrically
designed area of the rolled sheet is left unbonded and also within this thin interface
layer some material remains which plays the role of a gas-pressure source during superforuing
at a specific elevated temperature, gas blowing into the assembled die set is unnecessary.
The manufacturing process proposed here is termed RB/SPF(Roll Bonding/SuperPlastic Forming) .
Selection of a gas-pressure source which acts as STOP OFF in roll bonding and how to lock
the pressure source in the thin clearance may be key factors in this new processing.
Key words : sheet metal forming, superplasticity, clad rolling, diffusion bonding, gas blow
forming, gas generating source.