Papers in JOURNAL OF THE JAPAN SOCIETY FOR TECHNOLOGY OF PLASTICITY
(Vol.37 No.431 December 1996)
Development of Compressive Torsion Forming for Consolidation of Metal Powder
Eiji MAEDA, Naoyuki KANETAKE and Takao CHOH
(Received on March 1, 1996)
A new powder forming process called compressive torsion forming was investigated, which utilizes both
hydrostatic pressure and shear stress simultaneously. It was applied to consolidate pure aluminum powder and a
powder mixture consisting of pure aluminum and SiC ceramic particles. The density and radial distributions of
hardness and tensile strength of the consolidated specimens were measured to examine the effectiveness of
compressive torsion loading. The metal powder was easily compacted to produce a high-density sample, and the
hard oxide films on aluminum powder particles were broken and dispersed in the consolidated specimen together
with mixed ceramic particles. At 773K, a sample with homogeneous hardness and tensile strength distributions
can be fabricated in the short time and at low pressure, compared to use of conventional powder forming
processes.
Key words : powder forming, composite material, new forming process, consolidation, shear stress.
Improvements in Superplastic Forging Abilities of
Titanium Alloys by Adding a Cold-Pre-Deformation
- Development of Watch Case Made of Titanium Alloy IV -
Isao KUBOKI, Keitaro KOROISHI,
Yoshinobu MOTOHASHI and Mitsuji HIROHASHI
(Received on March 18, 1996)
High-temperature compression tests and superplastic forging tests have been conducted on three
titanium alloys with different initial microstructures. The hardness of a cold-prerolled Ti-4.5Al-3V-2Mo-2Fe
alloy decreases markedly, if the alloy is deformed in compression in the temperature range between 973K
and 1073K. Whereas the hardness decreases only slightly, even if the alloy is annealed at the same
temperature as the deformation is carried out. This large decrease in hardness may be due to dynamic
recrystallization caused by the deformation. Microstructure of the dynamically recrystallized specimen is
finer than that of a specimen subjected to static recrystallization. It was found that if this dynamic
recrystallization phenomenon is applied to a practical superplastic forging of a watch case, the forging time
can be considerably shortened. For example, when a preform made from the cold-prerolled Ti-4.5Al-3V-
2Mo-2Fe alloy is used, it is possible to forge the preform into a final watch case shape in about 2 minutes,
which are approximately one third of the time required in speed-controlled superplastic forging with a
statically recrystallized preform.
Key words : compression test, forging, superplasticity, Ti-alloy, watch case, cold rolling, recrystallization.
Deformation Analysis of ERW Pipes Subjected to 2-Roll Sizer
- Improvement of Pipe End Roundness of Thin Wall Pipes III -
Yoshiaki ITAMI and Matsuo ATAKA
(Received on March 19, 1996)
Recently, the requirements for dimensional accuracy of electric resistance welded (ERW) pipes have
became more strict. In this study, the deviation of the roundness of ERW pipes resulting from the sizing
process was investigated in detail using the 3-dimensional elastic-plastic finite element method (FEM)
and an experimental method. The effects of roll caliber, roll position, t/D ratio and geometry on the
roundness of pipes produced using the 2-roll sizing process were clarified. It was found that a 0.5% outer
diameter reduction resulted in products with the best roundeness regardless of the wall thickness and
initial profile of the pipes. The strain histories and deformations of the pipes were consistently
calculated using the FEM. It was found that the pipe end deformation could be controlled using a
combination of vertical and horizontal rolls with the same roll caliber.
Key words : residual stress, finite element method, finishing, sizing, roll forming, electric resistance
welded pipes.
Fundamental Nature of Tension Leveling
Fumio HIBlNO
(Received on March 25, 1996)
A thin metal sheet requires less tension to be extended during tension leveling,than that
required in the conventional tension test.The process of strain change in a sheet under
tension during its passage on a roll is examined experimentally to confirm the occurence of
this phenomenon during tension leveling.The occurence of the phenomenon is verified experi-
mentally and the following characteristics are observed: (1)the deformation begins before the
sheet coles onto contact with the roll and continues until it reaches the steady state;then
the inverse phenomenon arises at the outlet side, (2)the steady state zone does not occur for
small wrap angles, (3)the deformation capacity of the tension and roll diameter depend on the
wrap angle, (4)the wrap angle is the lain controlling factor in the sheet tension-strain re-
lation, (5)the curvature of cross bow has the sale sign as that of the roll periphery and is
generated during the transient deformation process on the outlet side. (6)the ratio of front
and back tension for a given wrap angle is expressed using Euler's equation for belt tension
for small diameters and becomes constant for large diameters. (7)deformation in the transient
zone is estimated to be induced by shearing strains equal to those occurring in both ends of
the sheet during static bending.The existence of the transient zones lust be confirmed
through theoretical analysis.
Key words : tension leveling, mechanism, experimental analysis, roll bending, stretch bending.
Fundamental Study on Clearance Compensation
Effect and Side Force in Shearing
Isamu AOKI, Toshinori TAKAHASHI, Hiromu SAITOH,
Akira GOTOH and Koto SAKAMOTO
(Received on April 5, 1996)
Currently, ultraprecision shearing of thin sheet metals is widely performed under near zero clearance. When performed
using a thin and slender punch, unbalanced clearance is compensated for by punch bending. However, the processing
mechanism operating when a blocky punch is used has not been clarifed until now. In this paper, we describe the
compensation mechanism during unbalanced clearance in such a shearing condition. For this purpose, model experimental
devices which enable measurement of forces acting on the tool and the tool movement were designed and manufactured.
Using these devices, the forces and movement were measured under various conditions, and the results obtained are
discussed in detail. It was shown that the unbalanced clearance is compensated in the case of shearing under fixed
supporting conditions. However, under full-free supporting conditions, the initial unbalanced clearance was shown to be
enlarged. This behaviour can he explained in terms of the magnitude and direction of the side force. Moreover, a shearing
experiment using a prototype die-set confirms the above-mentioned results.
Key words : shearing precision shearing, unbalanced clearance, side force, clearance compensation, supporting condition.
Analysis of Stress Distribution and Width Narrowing
in Hot Strip Rolling Using Boundary Element Method
Masashi TSUGENO, Makoto MIYASHITA and Junji KIHARA
(Received on April 8, 1996)
The tension stress distribution and width narrowing behavior of a rolled strip in the roll bite entry
region are analyzed as a 2-dimensional elasto-plastic problem using the boundary element method(BEM).
Our results confirm that the BEM is a useful method for stress distribution analysis. Also, the effect of
longitudinal temperature distribution on the width narrowing behavior in the roll bite entry region is
analyzed. Significant width narrowing occurs in the region within half the entry width of the roll bite
entry. However, the total amount of this width narrowing for the rolled strip is very small:. This indicates
that more detailed investigation should be undertaken regarding the width spread in the roll bite and the
interstand width change behavior in regions other than those close to the roll bite entry.
Key words : hot strip rolling, elasto-plastic BEM, tension stress distribution, width narrowing
Multi-Billet Extrusion Characteristics of
Zirconia/Stainless Steel Two-Layer Pipes
Zhongchun CHEN, Tadasu MURAKAMI and Keisuke IKEDA
(Received on April 9, 1996)
Multi-billet extrusion has been applied to fabricate a ZrO2/SUS304L two-layer pipe with powder-
binder compounds. and the effects of the particle size and size distribution of the powder, plasticizer.
extrusion ratio. and temperature as well as the dimensions of dies on extrudability of the pipe have been
investigated in detail. Broadening of the particle size distribution reduces the amount of binder necessary
to obtain sound extrudates for the SUS304L powder. while having little effect on the ZrO2 powder. The
addition of glycerol results in reduction of not only the binder content. but also the extrusion pressure for
both of the ZrO2 and SUS304L powders. Furthermore, a smaller amount of binder is required provided a
die with longer land is used. When the extrusion ratio is more than 20. the pipe is incompletely joined. The
forming process of ZrO2/SUS304L two-layer pipes is influenced by the flow resistance, compaction
characteristics of powder-binder compounds (which are determined by powder properties and binder
content) and the length of the die land.
Key words : extrusion, multi-billet, ceramic/metal composite pipe, ZrO2, stainless steel, powder, binder.
Springback Analysis of Side Bending Process of Phosphor Bronze Sheet for Springs
Hideo MORIMOTO and Akitake MAKlNOUCHI
(Received on April 10, 1996)
The process of side bending of a phosphor bronze sheet for use in springs is analyzed
under plane strain conditions using the elastoplastic finite element code ITAS-2D devel-
oped by one of the authors. and the calculated results are compared with the experimental
ones. For this material. the degree of springback after forming is large and it is diffi-
cult to predict the final shape of the product.
The computer program is based on the up-
dated Lagrangian scheme, and one of the significant features is that no particular assump-
tion. such as those commonly used in the analysis of sheet bending. is required.
Another feature is that the exact boundary conditions at each incremental step throughout the
entire forming process are given. The difference between the calculated and measured angles
of the bent products is within d:0.5 degrees in most cases. and we conclude that this
analysis is very effective in designing the optimum bending tool geometry.
Key words : die bending, elastoplastic FEM, non-ferrous metal(Cu-8Sn).
Effects of Rolling Conditions on Surface Brightness of
Rolled Strips in Pair Cross Cold Rolling
- Surface Brightness of Rolled Strips in Pair Cross Cold Rolling I-
Hideo YAMAMOTO, Atsushi TOMIZAWA, Toru KANEKO,
Tetsuo KAJIHARA, Hideaki FURUMOTO and Kanji HAYASHI
(Received on May 7, 1996)
Generally the surface brightness of a rolled strip decreases as the oil film thickness increases in cold rolling.
Acoordingly, the improvement of surface brightness has been difficult under rolling conditions that make the oil film
thicker. Through basic investigations using a model Pair Cross mill, it is found that the surface brightness of a
rolled strip can be greatly improved in cold rolling with slightly crossed rolls. As the cross angle increases, the
number of mirodefects ( oil pits and marks transferred from the ground roll surface ) on the surface of the cold-
rolled strip decreases, even with the rollig speed of 800m/min. In cold cross rolling, a large diameter of the work
roll is more effective for improving the surface brightness than a small diameter, in contrast to the case of normal
rolling. This suggests that the transverse component of relative slip between strip aud work roll in cross rolling
has a significant influence on the improvement of surface brightness.
Key words : cold rolling, pair cross mill, surface brightness, surface roughness, slip, lubrication, tribology.
Development of Highly Accurate Bending System with Bend Angle Sensor
Toshiyuki OENOKI, Toshio OTANl and Masaaki TAKADA
(Received on May 27, 1996)
The principle of a bend angle sensor and a bending system equipped with this sensor are
described in this paper. The purpose of the development of this system is to avoid bend angle
errors caused by variations in the mechanical properties of sheets. The bend angle sensor
consists of a slit laser projector and a CCD camera. It is possible to detect a bend angle during
the bending process without contact with the sheet by using an image processing technique. The
accuracy of the detected angle is better than d: 0.1 degree. Then the NC system of the press
break is used to determine a reversal point based on the detected bend angle. Using this system,
one can achieve highly accurate bending of any material,within error of less than half a degree.
Key words : bending, intelligent machine, bend angle, sensor, image processing, press break.
Curling Analysis of Stretch-Bent-Unbent Sheet Metal
- Springback Analysis of Sheet Metal II -
Toshihiko KUWABARA, Susumu TAKAHASHI and Kenji ITO
(Received on May 28, 1996)
An elastic-plastic analysis method for predicting the magnitude of curling (residual curvature) of a metal sheet subjected
to bending-unbending under tension is developed to evaluate the effect of the stretching force, the ratio of the die profile
radius to the sheet thickness, the mechanical properties of the material, and the decrease of flow stress due to the
Bauschinger effect. The program code is applicable to normal anisotropic material the behavior of which is represented by
the Hill's quadratic yield function and its associated flow rule with the n-th power hardening law. The elastic-plastic
deformation analysis consists of five consecutive deformation processes: initial stretching process, bending process,
unbending process, unloading process, and springback process. Calculated results have shown that the magnitude of
curling decreases with increase in the stretching force and the ratio of the die profile radius to the sheet thickness. The
decrease of flow stress due to the Bauschinger effect also contributes to the decrease in the magnitude of curling.
Experimental verification of the present calculated results will be presented in the next report.
Key words : stretch-bending-unbending, elastic-plastic numerical analysis, plane strain, curling, Bauschinger effect.
Experimental Verification of Curling Analysis of
Stretch-Bent-Unbent Sheet Metal
- Springback Analysis of Sheet Metal III -
Susumu TAKAHASHI, Toshihiko KUWABARA and Kenji ITO
(Received on May 28, 1996)
Experimental verifications of the analysis method proposed in report 11 for predicting the magnitude of curling
(residual curvature) of a metal sheet subjected to plane strain bending-unbending under tension are demonstrated. It
is found from the observation of specimens after experiments that the stretching process occurs in an uniaxial stress
state, the bending process in a plane strain state and the unbending process in a plane stress state. Therefore, the
analysis scheme was modified. The experiments were conducted for I mm-thick sheet aluminum alloy A5182-O and
Al-killed steel. The die profile radii used are 3 mm, 5mm and 10mm and three different types of die (undercut die,
drawing die and rotational die) are examined. The residual curvature and the outer surface strain of each specimen
obtained using the modified analysis method were compared with experimental results. The computed results were in
good agreement with the experimental results.
Key words : stretch-bending-unbending, curling, outer surface strain, experimental verification, Bauschinger effect.
Development of Numerical Simulation Model for Forming Loop Spline
- Spline Rolling of Deep Drawn Cups II -
Ryoichi MATSUNAGA, Tatsuo OZAKI, Teruie TAKEMASU,
Ryuzo KAMASHITA and Hidehiko TSUKAMOTO
(Received on May 29, 1996)
In the previous paper, a new spline rolling method of a two-dies-plunge-feed type was proposed. It
was experimentally confirmed that, a spline is successfully formed by this method. In this work,
numerical simulations using the elastic¥plastic F.E.M. are performed to obtain information about an
optimum shape of an outer tool. Accurate simulation of this process is complex and time consuming, since
the outer tool touch at the workpiece by a complex generating motion. Therefore a simplified stretch¥bend
deformation model is proposed. The problem is treated using a plane-strain condition, neglecting the
influence of the bottom wall of the workpiece. The deformation process of the workpiece is experimentally
observed by means of visioplasticity. The deformation of the workpiece and the tooth profile of splines
obtained analytically agree fairly well with experimental ones. A new outer tool is designed using this
model. The height of the tooth, the tooth width on the pitch circle, the radii of curvature of the vertex and
the side wall and the bottom of the groove are optimized. The validity of this tool design concept is
confirmed by an experiment using this new outer tool.
Key words : rotary forming, form rolling, sheet metal forming, stretch forming, new forming process
spline, automatic transmission, simulation, optimum tool profile, Finite-Element Method