目的 エアジェットによる糸飛走において, ジェットノズル内での糸加速が1つの重要な因子と考えられる.そこで本研究では, 以下のテーマについて実験を行い, ノズル内部での糸張力付加機構について検討する.
1) ノズル内部の空気流れに関して, ノズル内各部の流量及び流速を実験的に求めて検討する.
2) 構造や太さの異なる糸について, 糸に付加される張力を測定し, レイノルズ数より与えられる空気摩擦抗力係数を用いた計算値と比較する.
成果 本実験によって得られた結果を以下に示す.
1) ジェットノズル内に設けられている吸い込みノズルの内径を増加させると, 駆動流によって発生する吸い込み流の量は増加する. (本実験では吸い込みノズル内径は最大で3mmであった).
2) 駆動流量を増加させても, 吸い込み流量の増加には限界がある.
3) 加速管には, 噴流中の糸に作用する付加張力が最大となる長さがある (本実験では長さ100mmの加速管を取付けた場合に最大の付加張力を示した).
4) 圧縮性流体の等エントロピー流れの式からノズル内各部の流速を求め, さらにこれをノズル内の糸に作用する張力を求める実験式に当てはめた結果, この理論値は実験値とほとんど一致した.

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A lockstitch sewing machine for industrial use has been fitted with a rotary angular meter and a rotary encoder to determine feed length and feed velocity of the needle thread during sewing operation at the range from 250 to 4000 rpm. The needle thread was winded around a V-pulley, having 31 mm in diameter. The V-pulley was mounted between the angular meter axis and the encoder axis on the arm of the machine.
The sewing has been made by employing the spun thred of # 50 and continuous filament thread of # 50 under the constant tension required to pull out the thread through a shuttle spring and constant stroke of the check spring.
Records of feed length curves and feed velocity curves during the stitch cycle have been analysed and the results are summarised as follows :
1) The range of turning angle of the arm shaft required for feed of the needle thread increases with increasing the sewing speed. Thus, when the speeds are lower than ca. 1500 rpm for the use of continuous filament threads and ca. 2000 rpm for the use of spun threads, the needle thread is fed intermittently. When the speed are higher than the above speeds, feed motion of the threads is transformed continuously.
2) θ_v.maxhas been defined as the turning angle of the arm shaft at which the feed velocity of the needle thread had reached its maximum value.In most cases the value of θ_v.max increases with increasing the sewing speed.
3) The maximum feed velocity ΔV_maxof spun threads, at θ_v.max, are greater than those of continuous filament threads; The values of all threads are independent on sewing speeds, except 4000 rpm. Feed velocity at 4000 rpm reache : approximately constant value during the stitch cycle, and its value is larger than feed velocity below 3000 rpm.
4) Value of Δ V_max, at fabric feed scale of 4 is greater than that of scale of 2 in all threads.

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The effect of stitch length (lu) on the dimensional properties (Uc = Cu × lu, Uw = Wu × lu, Us= Cu × Wu×lu²Uc/Uw = Cu/Wu, and t/l, where lu is the total length in the SKC, Cu is courss/uint fabric length, Wu is wales /unit width the SKC is the smallest repeating unit of the structure, t is the fabric thickness, and l is the loop length), the porosity P (%), the air permeability V (cc/cm²/sec), the thermal retaining propertyH (%), the bending length L (mm), and the tensile breaking strength S (kgf) and elongation E (%) of the 1 X 1 rib fabric knitted from a cotton yarn (c30s/l) is investigated experimentally.
The results obtained are as follows :
(1) Us is approximately constant, but Uc, Uw, and Uc/Uw are dependent on 1/lu or the fabric tightness K (=n√T/lu, where n is the number of loops in the SKC and T is the yarn linear density in tex).
(2) t/l and the weight per unit area of fabric increase with the increase of 1/lu or K.
(3) The increase of lu increases P and V, but decreases H.
(4) L in each direction (the course (0°), bias (45°), and wale (90°) directions) decreases with the increase of lu. For all lu, L increases with the increase of the angle to the course direction.
(5) S in each direction (the course, 22.5°, 45°, 67.5°, and wale directions) decreases with the increase of lu. The strenght efficiency of fabric is about 40% in both the course and wale directions.
(6) The increase of lu increases E in the course, 22.5°, and 45° directions, but decreases E in the 67.5° and wale directions. For all lu, E decreases with the increase of the angle to the course direction.

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