Applications: 1) Model HY51 is used for doubling and drafting slivers after pre-drawing, thereby improving fiber parallelization, decreasing combing power, and increasing output and combing quality. The combination of pre-drawing with lap winding is the most effective in the combing preparation process, and leads international trends. 2) Structure features:a) Creel Cans are located at one side of the glide path to provide convenient operating. A higher sliver guide and power feeding can effectively avoid alse draft on the sliver, with the direction of the sliver in the drafting system being in accordance with that on the glide path. The sliver changes direction before entering the draft system.b) Draft system: The 4-over-4-draft system and pneumatic press device are designed for stable and reliable pressing with simple structure. 4-over-4 rollers form three draft zones, i.e. the back, mid, and main draft zones. In the main draft zone, the draft rate can be adjusted according to web weight.c) Calenders: Four sets of calenders are arranged in an arc-way to impact one by one. During the impaction process, the lap sheets are drafted and impacted time and again, running in "S" form between calenders. This methody effectively prevents the lap from sticking.d) Lap formation press: During lap build up, radial pressure changes lead to moderate and identical tightness inside and outside the lap, thereby producing favorable lap formation.e) Electrical control: The control system consists of a PLC and touch screen, which is convenient to operate. With the main motor adopting an inverter, the winding speed changes during lap build up and can be controlled by PLC. Thus, high speed and excellent quality can be reached. The whole process, such as pushing slantways, turning over and moving the lap, lifting and clamping bobbins, etc. is automatic, with initial working conditions automatically reset. Main Technical Data border=0>;