double draft meaning in Chinese

联单
双区牵伸

Vertical double draft bull block
立式双层鼓轮
The article describes mechanics and features of this twisting frame with single reel and five rollers and double drafting system with its drafting form compared with other double drafting system and some typical fancy yarns introduced
摘要阐述了单摇架五罗拉双牵伸机构的机理和机器特点，叙述了与其他双牵伸形式的不同点，介绍了几种典型花式纱线。