Koichiro Toriumi

Image Analysis of Woven Fabric Surface Irregularity

Applying image analysis to fabric quality evaluation is suggested as a substitute for human inspection of fabric surfaces. A fabric image is captured on an image scanner, and from it, the coefficient of variation and power spectra of yarn interval are calculated as indices of irregularity in the yarn arrangement. However, neither shows a significant relationship with the results of human evaluations. As another approach to the irregularity of fabric surfaces, the power spectral peak width of the intensity data is computed. The peak width, containing surface irregularity information, shows it is related to fabric quality. The study also shows that the peak width changes with the back beam height.

Twisting Mechanisms of Open-End Rotor Spun Hybrid Yarns:

We have developed a mechanical hybrid yam spinning system that produces different kinds of yam on a modified open-end rotor spinning frame. In order to understand the characteristics of hybrid yam and produce novel yarns, it is necessary to investigate yarn formation and the twisting mechanism in the spinning rotor during yam production. Our results reveal that the rotor revolution generally results in combining the filament yam and the staple fiber strand. The fiber twist angle of the strand in a hybrid yarn is smaller than that of a rotor spun single yam with the same spinning conditions. Although a fed filament yam has a false twist inserted by increasing the filament over-feed, the filament yarn in the hybrid yarn has a smaller level of fiber twist angle in the same direction as the twist of the staple fiber strand due to untwisting of the false twist.

Measuring Cloth Fell Fluctuation on a Weaving Machine

In this paper, we use an oblique scanning method with an image scanner to capture the fabric surface image on the running air-jet loom and to develop a new approach to measure the fluctuation of the cloth fell point during weaving. Based on our theoretical analysis of the cloth structure formation process, we also propose a fluctuation index of woven fabric in the cloth fell as an evaluation parameter for stable beating-up motion during weaving.

Woven Fabric Quality Evaluation Using Image Analysis

As a factor important to fabric quality, reed marks are studied by theoretical and experimental methods. In order to analyze their appearance, the power spectrum of a fabrics image is simulated in terms of that fabrics geometry. These power spectra offer peaks of wavelength coincident with the reed spacing. Further, they are used as an indicator to explain reed marks in terms of packed warps. At this same wavelength in experimental power spectra, there is also a peak that exhibits dependence on fabric quality. This peak adequately describes the appearance of the reed marks and thus can be used as a quality indicator for a woven fabric.

Novel Observation Technique for Contact Condition of Fabric

An observation technique is developed to provide a fundamental understanding of the surface contact condition between the human body and clothes. As a substitute for the body, transparent silicone rubber is used. The contact condition between the rubber and fabric is observed through the rubber using photomicrography. The method visualizes contact condition changes for different contact pressures and fabric structures. Using the relationship between the contact condition and the pressure, it is useful to estimate the two-dimensional distribution of contact pressure, which is important in clothing comfort.

Combination effects of open-end rotor spun hybrid yarns

We have developed a mechanical hybrid yarn spinning system that produces different yam types on a modified open-end rotor spinning frame. In order to improve yam properties and produce novel yams, we investigate the effects of combinations with typical hybrid yams by inserting two filament yarns with varying filament over-feeds. The results are a new rotor spun loop (RSL) yam made by combining two aspects of typical hybrid yarn production into one process, and an RSL yam where a filament yam, fed with a core filament over-feed (CFOF), is located in the center of one yarn and the other filament yam, fed with the effect filament over-feed (EFOF), makes a loop on the yarn surface. The stable conditions of RSL yam production are within a range of EFOF ≧ 4 (m/min) and -6.0 << CFOF << -4.0 (m/min).

BISPECTRUM EVALUATION OF COMBINATION AND BLEND YARNS

The bispectra of combination and blend yarns made on a spun silk spinning system are discussed, along with bispectra of mathematically idealized combination yarns. For comparison, the bispectra of a random combination yarn and two types of pseudorandom combination yarns generated by a computer simulation are calculated. Furthermore, the effect of periodic yarn irregularity on the bispectrum is estimated.

Bispectra of Sliver Irregularities

This study examines whether sliver irregularity can be evaluated by using a higher order spectrum, that is, a bispectrum. The thickness variations of slivers drafted with a drawing frame were measured with an evenness tester, and the bispectra of the slivers were calculated. The bispectrum of a mathematically idealized sliver was obtained, and bispectra of a random sliver and two pseudo-random slivers generated by a com puter simulation were calculated.

Effects of Pin Drafting on Irregularities of Sliver Made from Fine Denier Fibers

To improve the quality of spun yarn made from fine denier fibers, the technique of pin drafting is examined and discussed. Slivers made from four levels of fiber fineness are drafted with an experimental pin drafting system by changing the draft ratio. Deviations between indices of irregularities I corresponding to output and input slivers are calculated to evaluate the performance of the drafting process. Deviations of the gill sliver decrease with decreasing fiber denier. This phenomenon can be explained by the larger number of fibers contacting the pins of the gill fallers and the greater interfiber cohesive force with decreasing fiber denier. Irregularities of sliver from fine denier fibers are effectively negated by an appropriate pin drafting system.

MORPHOLOGY OF POLY (BUTYLENE TEREPHTHALATE)/POLY (BISPHENOL A CARBONATE) MELT BLENDS

Morphology and mechanical properties of poly (butylene terephthalate) (PBT)/poly (bisphenol A carbonate) (PC) and PBT/PC/di-n-octadecyl phosphate (DNOP) melt blends have been examined as a function of PC fraction with DSC, X-ray diffraction, FT-IR and SEM. Mechanical properties and dynamic viscoelastic properties of the blend filaments were also studied. The cross section of 90/10/0.5 blend etched by 4 vol% CH2Cl2/CCl4 mixture shows one phase structure, while network structure of PBT rich phase is observed for 70/30/0.5 blends, further the 10/90/0.5 blend is dissolved by the mixture. Two glass transitions are observed in DSC curves for 70/30/0.5 to 30/70/0.5 blends. The lower glass transition occurs at about the constant temperature, while the temperature of higher glass transition increases with the PC fraction. It is considered that the above two transitions are ascribed to PBT rich and PC rich phase, respectively. For 100/0 to 50/50 blends, dynamic storage modulus drops drastically at the glass transition temperature of PBT rich phase, whereas it drops at that of PC rich phase for 30/70 to 0/100 blends. Youngs modulus and yielding stress of PBT/PC blends are higher than those estimated by assuming the additivity. Therefore, must be strong interactions between PBT and PC chains. The amount of transesterification occurring between PBT and PC chains is too little to be observed by FT-IR. Accordingly, the interaction can be caused by rearrangement of chain packing with mutual diffusion of the chains. This indicates partial miscibility between PBT and PC chains in the melt state. The crystallization of PBT chains in the blends is restrained by PC chains. In the PBT rich phase, crystallization rate becomes slower and the cold crystallization becomes unclear with diffusion of PC chains. On the other hand, PBT chains in the PC rich phase crystallize suddenly when the temperature exceeds the glass transition temperature of the phase. The morphology and the higher glass transition become clear by addition of DNOP. It is considered that DNOP accelerates the degradation of PBT chains.