The ideal effect of draft drawing machine machine is attached unevenness to zero ideal fiber transmission requirements consistent point. In practice to achieve ideal draft is very difficult the current draft form is pursuit of fiber acceleration relative concentration theory is through reasonable distribution of friction field to achieve the effective control of motor fibers. In the ideal location for the front jaw are in a close to single fiber guiding force was greater than that of the control force and provide fiber transmission acceleration to obtain a stable and relatively concentrated fiber accelerated point distribution can effectively reduce the draft additional unevenness.

In the practical application of double apron drafting system can realize friction field distribution of relatively reasonable fiber accelerated point relatively concentrated but ideal draft still have great differences. In order to complete the drafting is to ensure smooth fiber by the guiding force is greater than the control force and can meet the fiber speed of acceleration. Mainly concentrated in the area before the drafting. Zone in front of the guide by the front belt roller and the front roller pull formed the front jaw and provide its size by front nip pressure, contact area, friction coefficient is decided. Before control is by, bottom pin elastic jaw friction and fiber friction provides its influence factors are two aspects: the external effect at a pressure such as gripping nip pressure, upper and lower pin elastic nip formed by the elastic force; secondly by draft shall self body structure and the formation of friction field such as roving twist formed torque, hook, not straight fibre entanglement and other. General externally applied pressure is stable by Luo pull pressure, Luo pull gauge, nip gauge to adjust; shall be a structure formed by the contact force has larger volatility must of fiber length, fiber distribution of straight and parallel, hooked fiber number morphology, residual twist of influence here and the size of the changes also directly affect the fluctuations in the speed change point position.

The spinning area also has important influence on the drawing effect. The drafting of guiding force by a double apron jaw jaw after provide control force by twisting roving hugs and friction and roller and the back roller forming of the jaw after holding provides. Drafting of the friction field in a V shape draft the reasonable region increased control rod drawing friction field has also been improved to other simple drawing friction field distribution for the poor. To reach the position of fiber acceleration drawing effect better will get ideal and stable.

Drawing machine is used in textile machinery and equipment, production process is very much, in the textile factory production has a called spinning process, this is the last working procedure of the textile mill, sit in the process of products is the final styling products. This process is very important, so the drafting device of spinning machine for this process to the role is particularly important.

Drawing machine in the spinning process on the production of the quality of the products is mainly determined in the process of drawing machine, drawing machine of sand a uniform quality or is effective in controlling the fiber drawing is a key in the use and main equipment maintenance and maintenance.