Initial Roll Research Articles

粉末圧延法によるＮｉ‐Ｔｉ合金薄板の製造と形状記憶特性

Ni-Ti alloy strips of the 54.8% Ni composition have been processed by direct powder rolling of blended elemental Ni-Ti alloy. The effect of the roll diameter and the initial roll pressure on the thickness and density of green strips are described. It is found that the coherent and flexible green strip has density of 65/70% theoretical, that the thickness of the green strip has been 1.2% of the roll diameter. The green strip has been sintered and then re-cold rolled. Sintering has been carried out in a vacuum at the temperature between 850°C and 1050°C. The density of the re-cold rolled strips reached at 93% to 97% when the total amount of deformation by re-cold rolling was 30% to 50%. It is found that shape memory behaviour of the fully processed strip is similar to conventional alloy.

Fabrication of high modulus films by solid state rolling

AbstractSolid state rolling of semicrystalline polymers represents a high speed process for producing oriented, high modulus films, tapes, and sheets. The important process variables include roll temperature, thickness of initial sheet, roll speed, take‐up tension, roll diameter, and initial morphological state of the polymer. Roll temperature controls both the extent of maximum deformation and the rate of rolling. A minimum temperature exists for each polymer below which the orientation process is sharply limited. This condition is similar to the limitation present in the hydrostatic extrusion process, in which the alpha crystallization temperature limits the orientation process. Roll speeds as high as 20 m/min have been realized. It is apparent that film thickness and thickness reduction ratio have a strong effect on the ultimate rolling rate. The process, as currently practiced, is adiabatic, and therefore, heat transfer limited. The take‐up tension influences the extant of orientation in the amorphous phse of of the polymer. This in turn affects its thermal and chemical stability. The effect of roll diameter is to limit the extent of thickness reduction by causing roll‐film slippage when the roll dianmeter to thickness reduction ratio is below some as yet undetermined value. The initial morphological state of the polymer affects the amount of crystalline deformation possible, the surface texture of the rolled film, and the tear resistant of the oriented film.

Estimation of Nonlinear Ship Roll Damping from Free-Decay Data

A common method of assessing the damping present in ship rolling motion is to perform a free-decay experiment, in which, in the absence of waves, the ship is given an initial roll amplitude and then released. By processing the resulting decaying, oscillatory trace it is possible to estimate quantitatively the degree of damping, even when this is nonlinear. In this paper an approach to the estimation of nonlinear damping is proposed which involves the use of a cubic spline interpolation of the peak amplitudes, followed by a parametric identification procedure. This method is first applied to some simulation data and then to some real free-decay data, obtained from a scale model of a ship, with various initial conditions. The experimental data are analyzed using two alternative parametric forms, that is, linear-plus-quadratic and linear-plus-cubic damping. A principal advantage of the proposed technique is that, because nonlinearities in the restoring moment are properly accounted for, it is not limited to small angles of roll. Thus it can be applied to free-decay data relating to very large initial roll amplitudes.

Compaction of Metal Powder by Rolling

AbstractThe powder rolling process has been analysed using the mechanics of powder compaction with a view to the prediction of the thickness and density of the strip. Factors such as roll speed, initial roll gap, feed rate or flowrate of the powder, and friction condition are discussed and a method of analysis taking account of these variables is described. Combined with the experimentally derived rigidity of the rolling mill, it is possible to determine the thickness and density of the strip produced using an electrolytic copper powder; calculated results agree well with experimental results. It is possible to apply the present method to other powders, provided the powder characteristics are known. PM/0268

Cooling Characteristics of the Twin-Roll Rapid Solidification Process

The microscopic solidification structure of a Pb–Sb eutectic alloy prepared by the twin-roll rapid solidification process has been examined to understand cooling characteristics of the process. The result shows that the average size and the area ratio of globular structure mainly consisting of Sb have minima for a certain roll rotation speed and decrease with decreasing initial roll gap. The effect of melt flow rate on the structure has not been detected under the adopted experimental conditions.Regarding the relationship between the solidification structure and the cooling rate of melt, a preliminary experiment of the rapid quenching from melt has revealed that with increasing cooling rate the structure consisting of Sb phase becomes globular and the average size decreases.Furthermore, velocity and temperature fields of the process were estimated using a mathematical model to discuss effects of key process parameters on cooling rates of the rapidly solidified metallic ribbons. The estimated results show that under the adopted experimental conditions the mean cooling rate in the melt region between rolls has a maximum for a certain roll rotation speed and increases with decreasing initial roll gap. These theoretical predictions qualitatively agree with results obtained from the observed solidification structure.

The application of ion plating to the continuous coating of flexible plastic sheet

Ion plating onto plastic substrates was demonstrated to give considerable advantages in that adhesion is increased and properties can be obtained which would normally require higher temperatures than the substrate is capable of withstanding. In order to coat large areas of sheet plastic it is necessary to achieve high deposition rates without creating high substrate temperatures. This is done in commercial apparatus by pulling the sheet substrate tightly over a very smooth cooled drum and transferring the plastic from an initial roll to a final roll over this rotating drum. Conventional resistance-heated sources are generally used, though induction and electron beam heating have also been applied. Simple diode sputtering results in damage to the plastic from both heat and electron bombardment. This can be avoided if a planar magnetron source is used. We created an apparatus which allows plastic sheet passing over a rotating drum to be subjected to an r.f. discharge either before, or simultaneously with, the deposition of material from a planar magnetron source. The material may be deposited directly from the source, or reactive processes may be used with carefully chosen reactive gas inlet points. The r.f. power is applied to the roll, which is isolated by carefully designed insulation techniques whereby the storage rolls and the drum are mounted within an r.f. cage. All motor drive shafts are insulated and only the surface of the drum over which the plastic is rolled is exposed to the general chamber; the rest of the apparatus is protected by a closely spaced earth shield. The results of experiments using planar magnetron sputtering sources, including the successful use of ion plating to give transparent conducting oxide films of In-10%Sn onto flexible plastic sheet, are given.

Interferometric observations of the temperature structure in water cooled or heated from above

Controlled laboratory experiments were performed in a water tank to study energy transfer during cooling and radiant reheating of water from above. Accurate instantaneous temperature measurements were obtained using a Mach-Zehnder interferometer which did not disturb the temperature, radiation, and flow fields. The buoyancy induced flow field was visualized by employing an electro-chemical dye production technique. Cooling of initially uniform layer of water and stratification-cooling-restratification were studied. The experimental observation during cooling of an initially uniform temperature column of water indicated intermittent free convection near the surface. The phenomenon was characterized by randomly descending cooler plumes penetrating 10 to 25 cm into the warmer underlying region. The cooling rate had a decisive influence on the frequency and intensity of the descending parcels of water. For lower cooling rates the colder water usually descended in a form of sheets. Observations during cooling of initially stratified water showed that buoyancy driven convection occurred near the surface. The motion had an initial regular roll pattern, but as the cooling continued the roll pattern in the convective (mixed) layer deteriorated into motion similar to that observed during cooling of an initially uniform temperature layer of water. When the water was restratified by radiant heating, the circulation in the convective layer was suppressed, and the temperature profiles obtained were similar to those observed in a fluid during free convection between two solid parallel walls.

A Frequency Approach to the One-dimensional Cutting Problem for Carpet Rolls

The one-dimensional cutting problem is usually formulated as either an integer or dynamic programme. In this paper, it is pointed out that where (as in the carpet industry) few orders are received per day and quick processing of these orders is considered essential, these techniques can be of little use. An alternative method is developed to minimize the amount of scrap subject to keeping the stock required within reasonable bounds. This is achieved by placing restrictions on what lengths may be kept in stock, and the only knowledge required to determine these restrictions is the average initial roll length and the distribution of order lengths.

粉末圧延による溶加材の製造

Aiming at manufacturing of filler metal for overlay welding, generally, produced in small quantity and various grades, by means of powder rolling a trial making of powder rolling equipment and an investigation of manufacturing conditions were made.A new powder feeding method for keeping compacting rate constant was investigated.Using relationship among density and thickness of green strip, rolling load and initial load (or initial roll gap), a controlling method for compacting a green strip of appointed characteristic could be obtained.After welding test it was confirmed that a strip produced with only compaction and sintering was possible to be used as filler metal.

Eccentric Landing with Heavy Masses at the Wing Tips

An eccentric landing of a conventional aircraft carrying heavy masses at the wing tips is investigated. The landing gears make contact with the ground one after the other, the second contact taking place before the shock absorbing process of the first gear is completed. The following results are of interest. (a) In eccentric landing with heavy tip masses the effective mass acting on (or the drop mass of) one shock absorbing unit may be larger than one half of the total mass of the aircraft. (b) The magnitude of this mass depends on the ratio, radius of gyration of the aircraft in roll to the undercarriage tread, on the initial roll angle, and on the roll velocity at the moment of the first contact. (c) Since the time span between two impacts and the magnitude of each impact depend on the initial roll angle and roll velocity and both can have any values, within certain statistical limits of course, an asymmetric wing vibration can be generated and have larger effects on wing stresses than the symmetric vibration due to the symmetric landing. (d) Parameters defining the landing gear strength are in general three: (1) sinking velocity, (2) roll angle, and (3) roll velocity. (e) Available information concerning the shock absorber characteristics is insufficient to bring the subject to a conclusion. I t appears, however, that for large tip masses the shock absorption capacity of the gear should be checked in two cases at least; (1) in the case corresponding to symmetric landing shock (small drop mass and large sinking velocity), and (2) in the case of eccentric landing shock (large drop mass and small sinking velocity).