RU2321691C2 - Method for regulating linear density of fibrous covering and sliver on carding machine - Google Patents

Abstract

FIELD: textile industry.

SUBSTANCE: method for regulation of linear density of fibrous covering and sliver involves pneumatic transportation of fiber; distributing fiber among hoppers; feeding air flow through pneumatic chambers having perforated walls; determining linear density of fibrous covering from average predetermined number of measurements of sliver linear density using sensor; regulating linear density of fibrous covering when average sliver linear density deviates from nominal density by value exceeding upper and lower tolerance bands which are respectively defined from mathematical expressions: △T_s-u=△T_y-u·E_s-b·√m (1); △T_s-l=△T_y-l·E_s-y·√m (2), where △T_s-u, △T_s-l are respectively upper and lower tolerance bands of sliver, tex; △T_y-u, △T_y-l are respectively upper and lower tolerance bands of yarn, tex; E_s-y is total extension from sliver to yarn; m is number of sliver folding passes at sliver transition portion.

EFFECT: increased uniformity in linear density of fibrous sliver covering and reduced consumption of fiber in yarn production.

Description

The invention relates to the textile industry and can be used in spinning, for example on card machines with hopper feeders.

A device for cleaning fibrous material is known (RU No. 2078158, D01G 9/06, 1997), the use of which in the composition of the hopper of the carding machine causes the fibrous material to be cleaned alternately on both sides of the hopper. In addition, a change in the direction of the air passing through the formed layer of fibrous material from one wall of the hopper to another leads to the formation of a more dense and uniform in linear density flooring. The disadvantage of this device is the inability to change the degree of influence of the air flow on the fibrous flooring in order to control its linear density.

In addition, a device is known for controlling the linear density of a fibrous product (SU No. 1171581, D01G 23/06, 1985), which implements a method for controlling the linear density of a fibrous floor in a hopper of a carding machine, including pneumatically conveying the fiber, distributing it over the hoppers, and supplying an air stream through pneumatic chambers with perforated walls, determination of the linear density of the fibrous flooring using a sensor. However, a disadvantage of the known invention is the lack of determining the deviation of the linear density of the flooring from the nominal value at which it is necessary to exert a regulatory effect.

The prototype is a method of controlling the linear density of the fibrous flooring in the hopper of the carding machine (RU No. 2245403, D01G 23/00, 2005), including pneumatically transporting the fiber, distributing it through the hoppers, supplying an air flow through pneumatic chambers with perforated walls and determining the linear density of the fibrous flooring in the hopper, according to the average value of a certain number of measurements of the linear density sensor of the tape, when the average value of the linear density of the tape deviates outside the tolerance, the regulatory air Action by changing in the corresponding direction of the discharge of air supplied to the air chambers with perforated walls.

The disadvantage of this method is that when adjusting the linear density of the fibrous flooring, the requirements for uniformity in linear density of the final spinning product - yarn, as well as the parameters of technological processes at subsequent technological transitions are not taken into account.

The technical result of this invention is to increase the uniformity of the linear density of the fibrous flooring and tape, allowing to produce yarn in accordance with GOST or other regulatory documents, as well as reduce fiber consumption in the production of yarn.

The specified technical result is achieved by the fact that in the method of controlling the linear density of the fibrous flooring on a carding machine, including pneumatically transporting the fiber, distributing it over the bins, supplying an air flow through pneumatic chambers with perforated walls and determining the linear density of the fibrous flooring by the average value of a certain number of measurements of linear density tapes using a sensor, according to the invention carry out a regulatory action when the deviation of the average cheniya linear density of the tape from the nominal value to a value greater than the upper or lower tolerance fields which are respectively determined by mathematical expressions

where ΔT _l-top , ΔT _l-bottom - respectively, the upper and lower field tolerance of the tape, tex;

ΔT _p-top , ΔT _p-bottom - respectively, the upper and lower yarn tolerance field, tex;

E _l-p - a general hood from tape to yarn;

m is the number of additions of tape on the tape transition.

At the same time, they produce a regulatory effect when the actual linear density of the tape approaches the upper or lower boundaries of the tolerance fields

where ΔТ _f - the actual deviation from the nominal value of the linear density of the tape, tex;

wherein T _f is determined by the following formula:

- среднее арифметическое значение фактических линейных плотностей ленты, определяемых по n количеству замеров датчика линейной плотности ленты, текс;Where

- the arithmetic average of the actual linear density of the tape, determined by n number of measurements of the sensor of linear density of the tape, tex;

T _n - nominal linear density of the tape, tex;

_.Phi.i T - current value of the linear density of the tape measured sensor tex;

T _{f (i-1)} - the previous value of the linear density of the tape, measured by the sensor, tex;

K ₁ - safety factor.

In addition, carry out regulatory action according to the condition

where β is the minimum sensitivity of the control system, tex;

To ₂ - the coefficient of reduction of the tolerance field, taking on a value from zero to T _l-top / β.

The method is implemented as follows. The fibrous material transportation system feeds it into the hopper of the carding machine, which is equipped with a device for cleaning the fibrous material [1]. The source of air discharge creates an air discharge in the pneumatic chambers of the device, which, using the means of changing the direction of air flows, leads it to the perforated walls located on opposite sides of the hopper. Alternating suction of the fibrous flooring with air flows from opposite sides of the hopper, together with the air inlet in the pneumatic conveying system of the fibrous material, creates the conditions for the formation of a layer of fibrous material of a certain density and its movement along the hopper. The higher the air discharge created by the source of air discharge, the more dense the fibrous flooring is formed. In accordance with changes in the linear density of the flooring in the hopper, the linear density of the fibrous tape at the exit of the carding machine also changes. Thus, when the degree of air discharge changes, the linear density of the fibrous flooring in the hopper of the carding machine is regulated. The current value of the linear density of the tape at the exit of the carding machine is measured using a sensor. Each measurement of the linear density of the tape is pushed onto the stack containing n measurements, with each new measurement crowding out the last in the stack [2]. The number of elements in the stack is determined in accordance with the condition

where n is the number of measurements of the linear density sensor of the tape;

L is the length of the fibrous flooring from the area of perforated walls to the feed cylinder, m;

l is the width of the perforated walls of the hopper, m;

T _cm - the planned duration of the shift, hour;

τ is the time interval between reading sensor readings, hours.

The regulatory effect occurs when the average linear density value deviates from the measurements of the sensor in the stack from the nominal linear density value by an amount greater or equal to the value of the upper or lower tolerance field of the linear density of the tape.

It is necessary to justify the upper or lower tolerance field, within which the actual linear density of the tape will not lead to a deviation of the actual linear density of the yarn outside its tolerance fields. The tolerance limits on the linear density of the yarn are regulated by GOST or another regulatory document. For example, GOST 1119-80 “Cotton Yarn” provides for a yarn with a linear density of 50 tex an upper tolerance field of + 2.0% and a lower margin of 2.5% of the nominal linear density, which is respectively +1.0 tex and -1, 25 tex.

In accordance with the spinning plan, the general extraction of semi-finished products from tape to yarn (E _l-p ) is known, which is approximately equal to 100. Therefore, the tolerance field of the tape should be proportional to E _l-p .

, где m - общее сложение лент. Следовательно, поле допуска ленты на кардочесальной машине может быть увеличено пропорционально

, которое не приведет к отклонению линейной плотности пряжи за пределы ее полей допуска. Таким образом верхнее и нижнее значения полей допуска можно определить по формуламThe spinning plan after the carding machines provides for a tape transition, which includes the sequential processing of the tape on two or more tape machines. Due to the addition of tapes on tape machines, the linear density is equalized proportionally

, where m is the total addition of tapes. Consequently, the tape tolerance field on the card can be increased proportionally

, which does not lead to a deviation of the linear density of the yarn beyond its tolerance fields. Thus, the upper and lower values of tolerance fields can be determined by the formulas

where ΔT _l-top , ΔT _l-bottom - respectively, the upper and lower field tolerance of the tape, tex;

ΔT _p-top , ΔT _p-bottom - respectively, the upper and lower yarn tolerance field, tex;

E _l-p - a general hood from tape to yarn;

m is the number of additions of tape on the tape transition.

If the average linear density of the tape deviates from the nominal value of the larger upper tolerance field or the lower lower tolerance field, the regulatory influence of the control system is necessary by changing the degree of air discharge in pneumatic chambers with perforated hopper walls, respectively, by ± ΔР.

A change in the linear density of the flooring in the carding machine can occur due to the influence of various irregular factors. Along with them, there are factors that can lead to a monotonous increase or monotonous decrease in the linear density of the tape over a period of time. Such processes can occur, for example, when the temperature or humidity changes. It is desirable that the control system could anticipate a possible deviation of the linear density of the tape beyond the tolerance in the values of previously performed measurements using the sensor, which can be expressed by the following condition:

where ΔТ _f - the actual deviation from the nominal value of the linear density of the tape, tex;

while ΔT _f is determined by the formula

- среднее арифметическое значение фактических линейных плотностей ленты, определяемых по n количеству замеров датчика линейной плотности ленты, текс;Where

- the arithmetic average of the actual linear density of the tape, determined by n number of measurements of the sensor of linear density of the tape, tex;

T _n - nominal linear density of the tape, tex;

T _fi - the current value of the linear density of the tape, measured by the sensor, tex;

T _{f (i-1)} - previous value of the linear density of the tape measured sensor tex;

K ₁ - safety factor.

If ΔТ _f exceeds the lower or upper tolerance field, the control system exerts its effect even when the actual linear density of the tape is within the tolerance, but can go beyond these tolerance limits after a period of time until the next reading of the sensor readings. The value of the coefficient K _{1 is} chosen depending on the nature of the control system, such as the inertia of the system, the time interval between reading the sensor readings, and also depending on the level of technical condition of the technological equipment and the stability of the process, the parameters of which will determine the difference between adjacent measurements of the linear sensor the density of the tape, that is, an increase in linear density: the larger this increment, the greater the value of the safety factor K ₁ .

Spinning plants are characterized by a high proportion of the cost of the feedstock - fiber. In the structure of the cost of yarn, the cost of raw materials is 75% or more. Therefore, the saving of raw materials is one of the factors that allows to achieve a lower cost of yarn and, accordingly, a higher profit from its sale. For example, with an average capacity of a spinning mill that processes 50 tons of fiber per day when yarn is produced within the lower tolerance range, the additional profit from saving raw materials can be up to 2 million rubles per year. In this case, the regulatory system should have a regulatory effect in accordance with the condition

Where. β - minimum sensitivity of the control system, tex;

To ₂ - the coefficient of reduction of the tolerance field, taking on a value from zero to T _l-top / β.

The value of β · K ₂ reduces the upper tolerance field of the linear density of the tape in the range from zero to the value of the tolerance field itself, which depends on the accepted value of the coefficient K ₂ . The greater the value of K ₂ , the more stringent requirements are imposed on the regulation system, since a more difficult technical task is regulation in narrower tolerance fields of the adjustable parameter.

Information sources

1. RF patent No. 2078152 IPC D01G 9/06 "Device for cleaning fibrous material." / Yu.P. Lebedev and others Publ. 04/27/97. Bull. No. 12.

2. RF patent No. 225403 C2 IPC D01G 23/00, G 01 No. 33/36 "Method for controlling the linear density of fibrous flooring in the hopper of a carding machine." / V.E. Goncharenko and others Publ. 01/27/05. Bull. No. 3.

Claims (1)

A method for controlling the linear density of a fibrous flooring and tape on a carding machine, including pneumatic transportation of fiber, its distribution in hoppers, air flow through pneumatic chambers with perforated walls and determining the linear density of the fibrous flooring by the average value of a certain number of measurements of the linear density of the tape using a sensor, characterized the fact that the regulation of the linear density of the fiber deck is carried out with a deviation of the average value of the linear plane the width of the tape from the nominal value by an amount greater than the upper or lower tolerance fields, which are respectively determined by mathematical expressions

where ΔT _l-top , ΔT _l-bottom - respectively, the upper and lower field tolerance of the tape, tex; ΔT _p-top , ΔT _p-bottom - respectively, the upper and lower yarn tolerance field, tex; E _l-p - a general hood from tape to yarn; m is the number of additions of tape on the tape transition.