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The present paper describes a tube drawing method with diameter expansion, which is herein referred to as “expansion drawing”, for effectively producing thin-walled tube. In the proposed method, the tube end is flared by pushing a plug into the tube, and the tube is then expanded by drawing the plug in the axial direction while the flared end is chucked. The forming characteristics and effectiveness of the proposed method were investigated through a series of finite element method (FEM) analyses and experiments. As a result of FEM analysis, the expansion drawing effectively reduced the tube thickness with a smaller axial load when compared with the conventional method. According to the experimental results, the thin-walled tube was produced successfully by the expansion drawing. Maximum thickness reduction ratios for a carbon steel (STKM13C) and an aluminum alloy (AA1070) were 0.15 and 0.29 when the maximum expansion ratios were 0.23 and 0.31, respectively. The above results suggest that the proposed expansion drawing method is effective for producing thin-walled tubes.

In this study, the effect of water-soluble components on the thermal fluidity of steam-treated bamboo powder was investigated. Bamboo powders were steam-treated at 180 or 200 °C for various steam treatment times. The bamboo powders were then treated with hot water to extract the water-soluble components. The flow rates of steam-treated bamboo powders that were either treated with hot water or not treated were measured using a capillary rheometer. In addition, thermogravimetry (TG) was also used to examine the differences in the thermal characteristics of bamboo powder treated by hot water extraction. The experimental results indicated that the quantity of hot water extract varied with the steam treatment temperature and time. Flow tests showed that bamboo powders not treated with hot water flowed, whereas those treated with hot water did not flow. The flow behavior and flow rate of the untreated powder became stable and high with an increase in the steam treatment time for steam treatment at 180 °C. For steam treatment at 200 °C, the flow behavior was more stable, and the flow rate became the highest by short time steam treatment. TG measurement of the powders suggested that water-soluble contains many volatile components, and the amount of volatile components changed along with the denaturation of the water soluble components. From these results, it was confirmed that not only the quantity of the water-soluble components but also denaturation of the water soluble component affects the thermal fluidity of the steam-treated bamboo powder.