Application of the hottest self leveling technolog

2022-08-14
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Application of self leveling technology in cotton spinning system (Part 2)

3 principle, type and characteristics of self leveling device

3.1 principle

change the drafting multiple in the drafting area to realize the leveling of products in process. Basic equation:

v2=v1e (1 ± △ t/t) or v1=v2[e (1 ± △ t/t)]... (1)

(1) where: V1 and V2 are the linear speed of feeding and spinning roller respectively, v2/v1= actual drafting multiple =d

e is the rated (Design) drafting multiple

g is the actual unit weight of feeding product, and the thickness t is the actual unit weight and rated (Design) of feeding product

△ g.(1) the difference of unit weight, expressed in thickness change △ t

when V1 is a constant, V2 the thickness of the feed changes linearly. When V2 is constant, V1 changes hyperbolically with the thickness of the feed

3.2 there are three types of self leveling: separate loop, closed loop, mixed loop

3.2.1 open loop: the control loop is not closed, the detection point is located behind the roller after the machine is fed, and the control point is located somewhere at the spinning point, which works according to the compensation principle

3.2.2 closed loop: the control loop is closed, and the detection point is located in front of the front roller of polyethersulfone (PES), a thermoplastic high molecular material with excellent comprehensive performance developed in 1972. The control point is located somewhere at the feeding point and works according to the feedback principle

3.2.3 hybrid ring: in the draft adjustment system, there are both open-loop and closed-loop, with the advantages of both. There can be two tests, one control, or one test, two control

3.3 type characteristics

3.3.1 open loop

(1) follow the direction of product operation, with the detection point in the rear and the control point in the front, and carry out real-time detection and real-time control of feeding products, with strong pertinence

(2) the detection point is in the feeding direction, and the speed is low, which can improve the detection accuracy

(3) the control point is in front. Although the speed is high, it has a linear relationship with the thickness of the feed, which is conducive to control

(4) after leveling, the external interference produced by the drafting system has no control ability

(5) the leveling length is relatively short, which has strict requirements on the running time of the control system. It must be synchronized with the time when the feeding work in progress reaches a certain speed change point in the drafting area. It is expected to have a full leveling effect on all medium and long segments above the leveled short segment. Otherwise, the effect is not good, and even worsens the evenness, so the stability is poor

3.3.2 closed loop

(1) in the direction of product operation, the detection point is in front and the control point is in the back. The feeding products are detected in the past and controlled in the future, which is poorly targeted

(2) the detection point is in front, the spinning direction, and the installation accuracy is high

(3) when the control point is behind, the speed is low, but it should have a hyperbolic relationship with the thickness of the feed, and the accuracy is affected

(4) the leveling system has the ability to control the external interference of the drafting system, so it has good stability

(5) the time from detection to control, execution and system operation is long, so the uniform segment is long

3.3.3 mixing ring

(1) melt open, and the closed loop is good at integration, which can homogenize short, medium and long segments at the same time

(2) the control mode is flexible, and there are many options, or set detection points at both ends of the feeding and spinning, set a control point at the feeding or spinning out, or set control points at both ends of the feeding and spinning out, and set a detection point at the feeding or spinning out, depending on the process needs

(3) due to the addition of detection points or control points, especially control execution points, its cost is high

3.4 open loop speed change point and time

3.4.1 speed change point. Take the center of the front roller jaw in the drafting area as the rectangular coordinate of the origin, a as the detection point, and the work in process is fed by the rear roller harness V1 according to the sagittal direction. V2 is the pull wire speed of the front roller, the center distance of the front and rear rollers is g, a, P, respectively, the actual width of the front and rear jaw, Xe is the speed change point, the fiber length is l, and the drafting multiple d=v2/v1. Then

xc=[2 (g-p+d · a) -l (d+1)]/2 (d+1) (note III)... (2)

the fiber head density in the sliver section is ahead of the sliver thickness (cross-section fiber amount) ф Value

ф= (L/2)[1+( σ/50) 2]...... (3)

(3), where l is the average length of fiber, σ Is the dispersion of fiber

oa=m. because the thickness of cotton sliver is regulated, when the feeding strip walks to point C in the drafting area, it should be regarded as the speed change point

3.4 it is required that the wear limit of the parts of the testing machine shall not exceed 50% of the dimensional tolerance value 2 system running time

the research shows that the speed change of the self leveling device can be synchronized only when the feeding strip runs from point a to point C. If the time of feeding from a to C is TF, then

tf=ac/v1={m-xc-0.5 × L [1 + (q/l) 2]}/V1......... (4)

if the system running time is set to TC, TC tf=0 must be made to synchronize. This means that the length of each fragment above the length of this short fragment can be completely homogenized

4 application in spinning system

4.1 the main defects of the original iron gun self leveling device on the cotton cleaning and winding machine are as follows:

(1) the surface curve of the iron gun is not strictly manufactured according to the hyperbola, which is often straight, and there is a control deviation

(2) the iron gun has high speed, large mass, large moment of inertia, slow speed change transmission and low sensitivity

(3) theoretically, the change of the speed ratio of the active and passive iron cannon depends on the position of the linear drive belt, but the belt has width, slip rate and climbing oblique effect, which all affect the change of the speed ratio

(4) the side shaft transmission parts and worms are rapidly worn, and there are many fault stops, which affect the efficiency. However, due to its multiple control mode rates, the consumption of parts is large

(5) manual weight adjustment is affected by the temperature and humidity of the workshop, which varies according to the experience and proficiency of the car stopper, and there are many uncertain factors

at present, most spinning mills in China still use cotton cleaning and winding machines. It is necessary to reform them, and the price of some small-size panels has increased. Many domestic companies have introduced more than 10 improved models, such as Wuxi Hengjiu zqb series, Sete SS series, Shenxin series, Xishan Lingte flt-3000b, seta se-200, Jintan Daewoo ysyh series, etc., which have two ways of frequency conversion and pressure adjustment, The common points are:

(1) the positive roll rate can be increased to 99~100%, the uneven weight of pure cotton is less than 1%, and the chemical fiber is less than 1.2%

(2) use the curved bar of the balance on the original machine as the detection point, and the balance roller as the control point

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