This article describes tribology on web handling which is the engineering science underlying the transport of webs such as paper, polymer film, copper foil, etc through processes successfully without incurring material defects and loss. However, when webs are transported and wound into a roll, some defects are often occurred. In this article, we show mechanism of occurring some defects such as wrinkles and slip. In particular, the materials are becoming ever thinner, and the processing precision is higher than in the past, so it is necessary to completely prevent defects such as slip and wrinkles. In addition, it is necessary to reduce stretching as much as possible, making low tension transport essential. As such, significantly progressing the web handling technology accumulated thus far has become an issue for the future.
Development of web wrinkling and roll edge shift are explained on the basis of FEM simulation under a roller tilt condition. A folded wrinkle is formed when one of wavy wrinkles goes up to the tilted roller and falls down on it after decreasing in width and increasing in height. This is the results of “normal entry law”. A wavy wrinkle tends to appear at a small angle of the roller tilt when imperfections (deviation from the ideal state) of both web strain distribution and web position against rollers during tensioning are large. A roll edge shift is formed by the tilt of a winding core or a non-uniform web tension distribution which bends a partial area of the web near the core or near the web tensioned end.
Web handling is one of the most impotent technologies for producing highly functional film. From the viewpoint of tribology, to estimate the friction between web and guide roller is effective measures for prediction of slip and wrinkle. Mechanism of slippage and wrinkle will be described and also proposed the best roller shape to prevent these defects.
Paper lint is recently one of the main factors of paper-related troubles in printers. Paper lint mainly include fractions of the cellulose fibers and paper filler particles. Those paper lint or dusts are generated through the paper feed and adhere to surfaces of rubber rollers or fly as dust inside of printers. This causes troubles such as double feeding or paper jams. The influence of the paper lint on friction decrease of feed rollers is one of the main topic and summarized with the basic information about the paper filler particles. And the standard evaluation method utilizing the roller friction against paper is also shown.
Automated teller machines (ATMs) are widely used in these days. ATMs are equipped with sheet separation mechanism to make banknotes separate one by one. The sheet separation mechanism is the mechanism called overlap-type sheet separation mechanism. The overlap-type sheet separation mechanism is used in apparatus that high reliability is required such as ATMs and bill counters although the mechanism is complex and high cost, because a multi-feeding is hard to occur in this mechanism. In the overlap-type sheet separation mechanism, when the piled paper sheets move between the feed-roller and the gate roller, a slippage caused by the resistance force that is proportional to the number of the piled sheet occurs between the piled paper sheet, and this slippage is the factor that is superior to the pressing-type sheet separation mechanism that is used in copy machines, printers, and facsimile.
A measurement technique of 2 dimensional birefringence distribution of the transparent film is explained. As a element technology, high-speed polarization image sensor has been used that is made by photonic crystal. Since it has 4 differential directional polarizer at neighbor 4 pixels, by applying 4 phase shift algorithm, birefringence can be calculated from 1 data. Thus by combining horizontal polarization pixels and time axis information, birefringence mapping data of the entire film can be obtained.
A traction drive is a device that transmits power between two rollers via lubricating oil. A traction drive is expected to be used for speed reducers for robot joint systems and automotive drive systems. However, cavitation occurs when the gas in the lubricant oil is being precipitated by the negative pressure in the rear vicinity of the contact part. The cavitation is considered to affect the flow of the rear part of an oil film and also causes various problems. Therefore, it is necessary to understand the characteristics of the cavitation in the traction drive. The operating environment of the high load and high peripheral velocity traction drive was reproduced, and the cavitation in the case of changing the load and the peripheral velocity was observed. Results confirmed that the cavitation expanded almost monotonously in the rolling direction up in low peripheral velocity condition, but tended to shrink as the peripheral velocity further increased. In addition, it was confirmed that the oil film was broken by connecting the atmosphere sucked from the rear part of the oil film and the cavitation.
This paper describes gas flow visualization under vibration on dry gas seals. Dry gas seals are widely used for turbo machinery such as compressor, turbo blower and so on because of their high sealing ability. They utilize fluid film generated by hydrodynamic grooves for sealing process gases and separate two seal plates. In the dry gas seals, there is high possibility to be supposed to vibration caused by rotational unbalance or external vibration. Under this background, many researchers have treated concerning about dynamic characteristics on dry gas seals. However, they are mainly focused on spring and damping coefficient. It is important to clarify the gas flow characteristics under vibration for enhancing the sealing ability of dry gas seals. Therefore, in this paper, we tried to visualize the gas flow in dry gas seal with spiral groove. Sinusoidal vibrations have been excited to test dry gas seal and the amount of leakage were measured. Simultaneously, in-situ observations have been done under two frequency conditions using high speed camera and then, PIV (Particle Image Velocimetry) analysis was conducted using the obtained visualization movie. Finally, the effect of frequency on gas leakage are clarified considering the gas flow in dry gas seal.