Papers in JOURNAL OF THE JAPAN SOCIETY
FOR TECHNOLOGY OF PLASTICITY

(Vol.41 No.469 February 2000)

Approximate Calculation of the Drawbead Deformation Process
in Aluminum Sheet
- Design Diagrams of Drawbead Restraining Conditions -

Haruyuki KONISHI, Akibumi FUJIWARA
Masatoshi YOSHIDA and Koji FUKUMOTO

(Received on January 6, 1999)

An approximated calculation model for the drawbead deformation process of sheet metals is proposed based on the bending theory of rigid plastic materials. In this model, the effect of work hardening on the process is incorporated under several assumptions. Drawbead force and thickness reduction due to drawbead deformation are obtained in terms of friction between sheet and tools, blank holding force, and the effective bending radius which characterizes geometrical effects of the tools. Calculation results for typical sheet aluminum alloys are compared with experiments, and the validity of the approximated drawbead model is confirmed. The experimental and calculated results are expressed by two types of diagrams. The drawbead restraining conditions can be aranged using these design diagrams.
Key words : sheet metal forming, bending, design, drawbead, aluminum alloy

Effects of Edge Clearance and Board Thickness on Shearing
Characteristic of Paperboard Die Cutting

Shigeru NAGASAWA, Yasushi FUKUZAWA, Akira HINE
Isamu KATAYAMA, Akinori YOSHIZAWA and Takeo FURUMI

(Received on January 18, 1999)

This paper reports on fundamental shearing model of paperboard die cutting. Several mechanical factors such as thickness, tensile stiffness, cutting directions, and specific cutting energy were investigated experimentally using a basis weight of paperboard. The critical condition required for complete cutting was discussed in terms of knife clearance, and the anisotropic shearing resistance in the cutting directions was also discussed in terms of the work hardening component and the plastic coefficient.
Key words : shearing, die cutting, knife clearance, paperboard, tensile characteristic

Simultaneous Joining of Resistance-Sintered Iron Powder Compact to
Different Ingot Metal Parts

Seijiro MAKI, Osamu HANEDA
Yasunori HARADA and Masao NAKAMURA

(Received on February 4, 1999)

With the intention of extending the resistance sintering technique to an assembly of sintered parts, the above experiment was conducted. Four kinds of metals, stainless steel, carbon steel, brass and duralumin, with wide-ranging thermal conductivity, are used as materials to be joined, and their joining conditions are examined in relation to the electrification condition, including the pressure applied. The experiment reveals that the thermal conductivity of the metal parts to be joined has a strong influence on the morphology of the joined area and hence bond strength, and that applying a high pressure just after the completion of electrification is effective in increasing the bond strength. In is concluded that the simultaneous joining of a sintered compact to ingot metal parts by resistance sintering is possible if the sintering conditions are properly chosen.
Key words : joining, sintering, resistance sintering, powder metallurgy, iron powder, parts assembly

Effect of Annealing on Distortion of Lead in Blanking IC Lead Frame

Hiroshi YAMADA, Manabu YAMASHITA
Nobuki YUKAWA, Takashi ISHIKAWA and Takashi JIMMA

(Received on March 3, 1999)

Since the wire-bonding quality is influenced by distortion of leads of an IC lead frame, strict specifications regarding lead distortion are requlired. It is considered that this distortion is caused by an imbalance of residual stress. Annealing after blanking the side of the lead (i.e. before blanking the top of the lead) enables the relief of residual stress and reduction of distortion. However, Fe-42%Ni alloy, a typical lead frame alloy, shrinks after annealing due to the Aa effect; it is then difficult to obtain sufficient accuracy during the subsequent process of blanking of the top of the lead. To reduce the distortion and to eliminate shrinkage of the lead frame, tension annealing is confirmed experimentally to be an effective process. As a result of applying tension annealing to a QFP(Quad Flat Package) lead frame with 100pins, the effect of its process on distortion and the shrinkage is similarly recognized.
Key words : IC lead frame, lead, blanking, residual stress, annealing, tension annealing, distortion, shrinkage

Effect of Temperature Increase during Plastic Deformation
on Ferromagnetic Property of Composite Magnetic Material

Satoshi SUGIYAMA, Takashi ISHIKAWA and Koukichi NAKANISHI

(Received on March 26,1999)

In press-forming of ferromagnetic/nonmagnetic composite material, an effective process for determining ferromagnetic property was developed using deformation-induced martensitic transformation. In a fixed-temperature compression test, the incidence of deformation-induced martensite was investigated, and measured values were expressed as a sigmoid function. The sigmoid function was introduced into the FEM analysis. During the ironing process, the distribution of effective strain, the distribution of working temperature and the incidence of deformation-induced martensite were calculated, and the ferromagnetic level was predicted to correspond to the incidence of deformation-induced martensite. Based on this experimental assessment, drawing was quite effective for obtaining strong ferromagnetic property compared to ironing. A magnetic flux density B4K (induction at H of 4000A/m) of 0.5T was achieved by drawing under cooling die.
Key words : material propety, ferromagnetic property, composite magnetic material, ironing, drawing, deformation-induced martensitic transformation

Mechanical Properties of Zirconia after Deformation at High Temperature

Toshio YOKOYAMA, Toru HORIGUCHI
Takayuki WATANABE and Shohko OHYAMA

(Received on April 1, 1999)

Yttria-stabilized tetragonal zirconia (Y-TZP) exhibits fine-structure superplasticity. Recently, examples of products formed using superplastic forging have been reported. Therefore, it is important to study the change of mechanical properties caused by deformation at high temperatures. In the present experiment, plates of zirconia were compressed in the temperature range of 1300'C and 1450'C and mechanical properties of deformed specimens were then evaluated. The bending strength of specimens compressed at temperatures higher than 1350'C slightly decreased as strain increased and fracture toughness also increased with it. The grain size of zirconia was increased as holding time in the furnace increased. The possibility that cracks in a zirconia plate were repaired by compression was studied. Cracks made intentionally on specimens were repaired by compression at temperatures above 1350'C, and the bending strength of repaired specimens was recovered. However, the cracks were grown by compression at 1300'C, and the bending strength of these specimens was not recovered.
Key words : forging, superplasticity, zirconia ceramics, bending test, fracture toughness, grain growth

Analysis of Profile Error Caused by Contact Length on Pinion Rolling - Development of Cold Form Rolling
for Steering Pinions I -

Masaru AIZAKI and Masana KATO

(Received on April 5, 1999)

Rack and pinion steering gears for passenger cars have been employing mainly hobcut helical pinions. Rolled pinions have recently emerged because of their merits of high productivity and strength. However rolled pinion profile errors arise by a complicated plastic deformation mechanism between rolling pinions and dies. The rolled pinion tooth face undulates cyclically. From experimentation the adoption of an integer overlap ratio of the pinion was found to have a good effect on the undulation. In this research, we proved that there are no structural defects in deformed metal, and the variation of the total contact length between the pinion and the dies causes the undulation. Rolled pinions are found to be sufficient for use in rack and pinion steering gears in terms of their performance and strength.ure.
Key words : form rolling, gears, pinions, profile error

Elastoplastic Analysis of Axisymmetric Shell
Using Hinge - Conical Membrane Element

Yasuto YOKOUCHI and Shinya KIKUI

(Received on April 5, 1999)

A type of membrane element or shell element is generally used in analyses of the large plastic deformation of a thin shell, such as in sheet metal forming, by the finite-element method. Although the membrane element is fairly efficient in computation, it sometimes gives poor results. In contrast the shell element gives a comparatively good solution but at a high calculation cost. We propose the use of a simplified axisymmetric shell element which adds concentrated bending stiffness into the membrane element. After implementing the formulation, classical elasticity problems and bulge problems of a circular tube described in literature are analyzed. Through comparisons of those numerical results with the classical solutions, the measured values and the results obtained using the shell element embedded in the general-purpose programs ABAQUS and MARC, the effectiveness of this method is verified.
Key words : sheet metal forming, tube forming, numerical analysis, elastoplastic FEM, concentrated bending stiffness, hinge element, axisymmetric shell

Fabrication of Three-Layer Pipes Composed of ZrO2 and
Stainless Steel by Multibillet Extrusion Method

Shinya IMAMURA, Tadasu MURAKAMI,
Keisuke IKEDA and Zhongchun CHEN

(Received on April 19, 1999)

Ceramic/metal three-layer pipes were fabricated by the powder multibillet extrusion method, and the extrudability, sinterability and mechanical properties of pipes were studied. Monoclinic-ZrO2 or PSZ powder and SUS304L stainless steel powder were used as the representative ceramic and metal, respectively. An appropriate binder content must be chosen to fabricate a soundly extruded pipe. Surface cracking after natural drying was prevented by adding glycerol or using PSZ powder. Soundly sintered pipes were not obtained by using monoclinic-ZrO2, however, use of PSZ enabled production of soundly sinterd pipe. The result of the pressure tightness test indicated that covering the ceramic pipe with metal effectively improves pressure tightness.
Key words : multibillet extrusion, ZrO2/stainless steel three-layer pipe, powder/binder mixture, sintering