Cylindrical deep-drawing tests were carried out for roll-bonded stainless-steel/aluminum laminates. The limiting drawing ratio (LDR) was found to be higher when a punch contact metal was strong material (stainless-steel) compared to the opposite case of reversed blank-set condition. In order to find the reason for the phenomenon, the effect of the blank-set condition on the maximum punch load for a given diameter of a blank and the fracture load at LDR was investigated. It was found analytically and experimentally that the fracture load of the laminate subjected to stretch bending at a punch corner was higher when a punch contact metal was strong material compared to the opposite case. From this result, it is clear that the difference in LDR between both the cases is mainly due to the difference in the fracture load of the laminate at a punch corner.

抄録全体を表示

In press forming, fracture of a sheet mostly occurs at a punch corner because the sheet is subjected to severe stretch bending there. The fracture load in stretch bending for sheet metal laminates has been investigated by performing stretch bending tests on a two-ply laminate of aluminum/SUS430 and a three-ply laminate of SUS304/aluminum/SUS430. The results show that the fracture load becomes lower with decreasing die-radius. For a two-ply laminate consisting of weak/strong layers, the fracture load is lower when the weak metal is located at a die side compared to the case of reversed sheet-set condition. An analytical method for the determination of the fracture load has also been presented. The predicted fracture loads are in agreement with the corresponding experimental results.

抄録全体を表示

When a sheet is drawn over a die corner, the sheet is subjected to stretch bending and subsequent unbending. This paper deals with the deformation behavior of sheet metal laminates in the stretch bending/unbending process. For two-ply laminates of aluminum/SUS430 and three-ply laminates of SUS304/aluminum/SUS430, the behavior of sheet thickness change and the loss of stretching force (i. e. the plastic energy dissipation) in the process are discussed based on the experimental results and the corresponding numerical simulations. The results show that the amount of change in sheet thickness increases with decreasing die radius. Especially for the two-ply laminate of aluminum/SUS430, the deformation behavior is strongly affected by the sheet-set condition of whether a die-contact metal is aluminum or SUS430. The loss of stretching force is affected by the die radius and the friction characteristics of the die-contact metals.

抄録全体を表示

Due to high productivity of tandem cold rolling mills, it is beneficial to produce not only mild steels but stainless steels by using the process, instead of conventional reverse rolling mills with smaller diameter of work rolls. Requirements to lubricant in order to realize the process are conflicting, which one side oil film thickness is required to be reduced to provide brightness of products, beside too thin film causes seizure and heat stratch.
In this study, an O/W emulsion is designed and developed to contend with these conflicting requirements. In order to make oil film thickness at inlet zone of roll bite be thinner, the droplet size is reduced down to about 1μm. Also, kinematic viscosity of base oil is increased up to 320mm²/s, which makes the film stronger and prevent heat stratch, even if the film thickness is reduced. Through laboratory tests and cold rolling tests using a production mill, the superiority of this type of lubricant is clarified and good surface brightness of SUS430 can be obtained with large diameter of work rolls in high speed rolling conditions.

抄録全体を表示

The forming limit of sheet metal laminates under a biaxial stress condition is investigated by performing punch-forming experiments on two-ply laminate of aluminum/SUS 430, three-ply laminate of SUS 304/aluminum/SUS 430 and their component sheet metals. The data of necking-limit strains of the laminates lie between those of their component sheet metals. A criterion of localized necking for the laminates, in the negative strain-ratio condition (β=ε₂/ε₁<0), is derived based on Hill's theory of localized necking. For the case of the positive strain-ratio condition (β=ε₂/ε₁>0), the modified Marciniak-Kuczynski-type analysis, which assumes that an initial inhomogeneity in a sheet develops into localized necking, is conducted with the consideration of void growth in the groove of the sheet. The calculated forming limit diagrams show the same tendency as seen in the experimental results. The effect of prestrain generated in the roll-bonding process on the formability is discussed.

抄録全体を表示

In the previous paper, the author has reported that the surface brightness is expressed as three functions of the inlet oil film thickness and the surface brightnesses of roll and sheet before rolling, and a system for estimating and controlling the surface brightness before rolling can be constructed by using this relation. In this paper, a new system for estimating the surface brightness after each pass in actual mill for cold rolling of stainless steel is proposed by developing this relation. In the new system, the estimation is carried out as follows: (1) Preparation of as hot rolled specimen, (2) Input of rolling conditions at each pass in actual mill, (3) Calculation of the inlet oil film thickness at each pass, (4) Determination of rolling conditions at each pass in laboratory mill, (5) Rolling in laboratory mill and measurement of surface properties of rolled specimen, (6) Surface brightness after final pass.
By using the new estimating system, the surface properties after each pass are measured and it is seen that the system is able to estimate the surface brightness after each pass in actual mill.

抄録全体を表示

The load prediction model of 17%Cr-7%Ni stainless steel in cold rolling has been developed. In this model, the flow stress equations included deformation-induced martensitic transformation and the mathematical model of rolling load based on the approximate theory of Bland & Ford are considered. The volume fraction of martensite by ferrite scope was modified by X-ray diffraction method. The flow stress were investigated from the tension tests of sheets prestrained by rolling with temperature range from 20°C to 200°C, and the flow stress equations were established from parameters of the volume fraction of martensite, material temperature, equivalent strain and strain rates. The rolling load, the volume fraction of martensite and the strip temperature calculated by this load prediction model were consistent with the experimental results. By using this load prediction model, it is made clear that the rolling load and the volume fraction of martensite depends on strip temperature and rolling speed greatly.

抄録全体を表示

Influence of roughness of contact surface of C1020 copper and A1050 aluminum sheets on bonding characteristics was experimentally investigated in roll bonding of copper/aluminum/copper laminated sheet at room temperature. The contact surfaces of the sheets were roughened by emery paper and grindstone prior to roll bonding. Minimum reductions in thickness for bonding (higher than 0.9 in area fraction of bonding at the contact surface) were 63%, 55% and 50% in the laminated sheet with no surface treatment (mean arithmetic roughness Ra=0.1 μm), emery paper surface treatment (Ra=1.2–1.7 μm) and grindstone surface treatment (Ra=3.1–3.6 μm), respectively. On the other hand, the bonding strength of the laminated sheet with/without surface treatment was lower than 10 MPa. In roll bonding of the laminated sheet with large interface roughness, the elongation and relative sliding of the sheets at the contact interface of the sheets in rolling direction were reduced to approximately 90% and 35%, respectively. The bonding mechanism of the laminated sheet with large interface roughness was discussed from viewpoints of the deformation and the relative sliding in roll bonding.

抄録全体を表示

Recently, to improve productivity of stainless steel strip, development of cold rolling technology in tandem mill is required.
Previous research works, however, show that a surface brightness of strip decreases due to increase of micro-defects such as oil pits caused by high speed rolling with large diameter work rolls. In this paper, to obtain high brightness surface in cold rolling, a new method for decreasing micro-defects by "Axially ground rolls", which are finished by grinding to axial direction instead of conventional grinding to circumferential direction, is proposed.
Main results are as follows:
(1) The surface brightness of stainless steel strip is significantly improved by rolling with axially ground rolls.
(2) This new rolling method has an effect to decrease the oil pits and the imprint of roll asperity on strip surface due to relative slip between roll and strip.
(3) Although a rolling friction is increased by this method, an occurrence of seizure is restrained.

抄録全体を表示

近年、日本のアニメ制作に3DCGが積極的に導入される様になっている。しかし、この表現に矛盾は無いのであろうか?また、この事によって、「日本のオリジナリティ」を代表すると言われてきた「アニメ」の表現はどんな変化をして行くのであろうか?この論文では3DCGの仕組みを通して「写実的表現」と「アニメ的表現」の違いについて考察してみたい。

抄録全体を表示

Survey on wastes required for reduction in paper, house, food, printing, pharmaceutical manufacturing and glass manufacturing industries was carried out by a hearing method, and their recycling systems using manufacturing processes of steel products were examined in order to enhance process linkage between the different industries and to decrease wastes emission. Paper sludge in paper, construction and demolition waste wood and waste plaster board in house, waste ion exchange resin in food, incineration ash in printing, inorganic sludge in pharmaceutical manufacturing and chemical division of glass industries were found by hearing of each company. The paper sludge as a sinter material, the construction and demolition waste wood as a blast furnace reductant, and the incineration ash of municipal solid waste as a molten slag by a electric furnace for steelmaking are hopeful from the viewpoint of the progress of their technology, the large treatment amounts and their efficient delivery. The calculated CO₂ emission of paper sludge utilization as the sinter material and that of scraped wood as the blast furnace is less than power generation by incineration, while that of molten slag of incineration ash utilized by electric furnace is larger than cement materials.

抄録全体を表示