EP3293297B1

EP3293297B1 - Method of controlling weft insertion into a shed in an air-jet weaving machine and a weaving machine for performing the method

Info

Publication number: EP3293297B1
Application number: EP17172416.4A
Authority: EP
Inventors: Josef Zak
Original assignee: Vuts AS
Current assignee: Vuts AS
Priority date: 2016-08-30
Filing date: 2017-05-23
Publication date: 2020-02-26
Anticipated expiration: 2037-05-23
Also published as: CZ2016520A3; CZ307028B6; EP3293297A1

Description

Technical field

The invention relates to a method of controlling weft insertion into a shed in an air-jet weaving machine, during which the weft thread is during its passage through the shed acted upon by an auxiliary air flow from relay nozzles, whereby weft arrival times are monitored and the parameters of the action of the auxiliary air flow from the relay nozzles during the next weft insertion are adjusted accordingly.
The invention also relates to a weaving machine with a control system of weft insertion into a shed, which comprises a main weft inserting nozzle connected to a source of compressed air and to a device for controlling weft insertion, whereby the main weft inserting nozzle is assigned to the beginning of the shed and a weft thread reserve inserted into the shed is assigned to the main weft inserting nozzle, whereby along the length of the shed are arranged relay nozzles, connected to the source of compressed air and to the device for controlling weft insertion. Behind the shed is arranged a weft arrival sensor, which is connected to the device for controlling weft insertion, to which a sensor of the revolutions of the main shaft of the machine is connected.

Background art

Fabric is produced on weaving machines, wherein at first a shed is created by warp branches and a weft, or a weft thread, is inserted through the shed. Subsequently, the weft is carried by a weaving reed to the fell of the fabric being formed. On air jet weaving machines, the weft is inserted in the shed by flowing air, when the weft thread is arranged in a weft metering device and passes through the main weft inserting nozzle (the front end of the weft yarn is arranged in the main weft inserting nozzle), which is with its outlet directed in a known manner to the weft inserting channel formed in the weaving reed in the direction of the width of the formed fabric. The main weft inserting nozzle is connected to a control device and it is also connected in a controllable manner to a source of compressed air, due to whose action the weft situated in the main weft inserting nozzle is swept at a required moment out of this nozzle towards the weft inserting channel in the weaving reed. However, particularly in the case of greater fabric widths or insertions of heavy weft yarn, a decrease in the velocity of the weft movement through the weft inserting channel in the direction of the weaving reed length has a negative impact and therefore relay (auxiliary) nozzles are arranged along the weaving reed length and are connected to the source of compressed air in a controllable manner. During the weft insertion into the weft inserting channel, the relay nozzles are directed with their outlet holes of the compressed air in the direction of the insertion, i.e. in the direction of the weft movement or obliquely to the weft movement.
Nevertheless, the operation of the relay nozzles, i.e. blowing the air into the weft inserting channel, is energy intensive, especially if it is to be performed over the entire period of the weft insertion along the entire length of the weft inserting channel. Therefore, to save energy, an arrangement of the relay nozzles along the length of the weft inserting channel in several groups (sections) has been introduced. By means of the relay nozzles the compressed air is forced into the weft inserting channel successively according to the current position of the weft fell moving through the weft inserting channel. That means that the individual sections of the relay nozzles are started one after another along the length of the weft inserting channel, possibly even with the intervals of the immediately adjacent sections of the relay nozzles slightly overlapping each other, to avoid "dead zones" in the weft inserting channel.
To ensure that these consecutive operations of the relay nozzles are effective, each section of the relay nozzles has a certain time interval of operation within the weft insertion. The length of this interval also influences the total consumption of compressed air and therefore the overall energy requirements for weft insertion and fabric formation. On the other hand, if the selected interval were too short or if it were inappropriately placed on the timeline of the operation of the individual sections of the auxiliary nozzles, weft insertion errors would occur.
EP 1 384 800 discloses a method of controlling weft insertion on an air-jet weaving machine in which the relay nozzles are divided into groups (sections) in the direction away from the main weft inserting nozzle towards the opposite end of the weaving reed, whereby the individual relay nozzles are connected through control valves of the sections of the relay nozzles to a source of compressed air. The control valves are connected to a control device, which is further connected to a system of monitoring arrival times of the individual weft threads through a weft inserting channel and to a correction system of the time intervals of the relay nozzles.
The machine control system operates with set weft arrival times and corresponding lengths of the intervals of operation (blowing) of the individual sections of the relay nozzles. The system of monitoring the arrival times of the individual weft threads monitors the weft arrival times and passes either the individual arrival times or the average values of several arrival times to the correction system which compares these actual arrival times with the set limit values of the weft arrival times. If the current arrival time does not fall within the defined interval, the correction system will issue a correction signal to the control device to correct the start and/or end of the interval in which the respective auxiliary nozzle section operates, i.e., forces the compressed air into the weft inserting channel, to perform the next weft insertion. The correction signal is an instruction to add a correction time before and/or after the set interval of operation of the respective relay nozzle section and so this interval of the respective section abruptly increases. At the same time, the solution according to EP 1 384 800 also applies a similar technique to the control system of the compressed air pressure of the relay nozzles and of the main weft inserting nozzle.
The main drawback of this solution is essentially firmly set length of the intervals of operation of the individual sections of the relay nozzles and possible correction of the length of these intervals which have been preset by basically fixed values on the basis of the result of comparison between the desired weft arrival time and the actual weft arrival time, which allows to reduce slightly air consumption and therefore also energy intensity, while maintaining the weft insertion parameters.
From US 2009/084461 is known method for introducing a weft thread in a weaving machine which comprises a device for introducing a weft thread, which method comprises adjusting a control parameter and adapting the number of insertions for determining the mean deviation of an insertion parameter. Weaving machine comprises a device for employing an abovementioned method.
From US 6 314 335 is known a fuzzy control apparatus for a jet loom detects a flying state of a weft yarn, performs, based on a detected value thus detected, fuzzy inference to determine a modification amount to a rotational frequency of a motor, drives the motor to rotate at a predetermined rotational frequency, and corrects the rotational frequency of the motor based on the correction amount.
The aim of the invention is to optimize the operation of the relay nozzles and thus allow higher savings in the consumption of compressed air and reductions in energy requirements for the weaving process.

Principle of the invention

The goal of the invention is achieved by a method of controlling weft insertion into a shed in an air-jet weaving machine, whose principle consists in that from weft arrival times during a plurality of successive weft insertions the statistical mean value and the statistical deviation from this value is determined for each section of the relay nozzles along the length of the insertion, whereby the mean value is used for setting the mean value of the interval of the engagement of each section of the relay nozzles to support the insertion depending on the angle of the working cycle of the machine. The value of the statistical deviation is multiplied by the coverage factor of weft arrival and this multiplied value is used for setting the start and the end of the interval of the engagement of each section of the relay nozzles to support the insertion depending on the angle of the working cycle of the machine, and so the moments of the start and the end, and therefore the length of the engagement of the individual sections of the relay nozzles are adaptively and automatically adjusted on the basis of the statistics of the arrival times of a pre-determined number of previous insertions and, consequently, the consumption of compressed air and the energy intensity are adaptively optimized according to the current actual conditions on the machine.
The principle of the weaving machine for performing the invention consists in that the device for controlling weft insertion is provided with means for monitoring the statistics of weft arrival times of a pre-determined number of successive insertions and means for determining the mean value and the statistical deviation for each section of relay nozzles or each relay nozzle from the measured values of the weft arrival times of successive weft insertions and means for setting the mean value as the mean value of the interval of the engagement of each section of the relay nozzles (8) to support insertion depending on the angle of the working cycle of the machine and means for multiplying the value of the statistical deviation by coverage factor of probability of weft arrival and using the multiplied value for setting the start and the end of the interval of the engagement of each section of the relay nozzles to support insertion depending on the angle of the working cycle of the machine, and so the moments of the start and the end, and means for adaptive and automatically adjustment of the length of the engagement of the individual sections of the relay nozzles on the basis of the statistics of the weft arrival times of the determined number of the previous insertions, which allows adaptive optimization of compressed air consumption and energy intensity in accordance with the current actual conditions on the machine.

Description of drawings

The invention is schematically represented in the drawing, where Fig. 1 shows a weaving machine with sections of relay nozzles, Fig. 2 is a graph of dependence of the position of the weft fell on the angle of the machine and Fig. 3 is a graph of the timing of the operation of the individual sections of the relay nozzles operating according to the method of the invention.

Examples of embodiment

The invention will be described with reference to an exemplary embodiment of a weaving machine with a set of relay nozzles along a weaving reed.
The weaving machine comprises a system of mutually interconnected and/or coordinated mechanisms to form fabric. For the purposes of the present invention, not all the parts of the weaving machine will be described - only the parts which are necessary for performing the present invention will be described in the specification.
The weaving machine comprises a bobbin 1 with a weft thread 2 which is unwound from a weft metering device 3 to be inserted through a shed. The weft thread 2 is guided from the weft metering device 3 to a main weft inserting nozzle 4 , from which the weft thread 2 is inserted by compressed air flow as a weft 5 to the shed 6 created as an opening by the warp threads 7 raising and lowering to form the upper and lower branches of the shed 6 . The main weft inserting nozzle 4 is controllably connected to a source 10 of compressed air. The compressed air supply to the main weft inserting nozzle 4, and, in case of need, also its pressure is controlled by the device 11 for controlling weft insertion (picking the weft 5 into the shed 6 ), e.g., through a control valve 16 .
A row of relay nozzles 8 is assigned to the shed 6 along its length, the relay nozzles being divided into sections 9 . The relay nozzles 8 of one section 9 are controllably connected to the source 10 of compressed air, whose supply is controlled by the device 11 for controlling weft insertion (picking the weft 5 into the shed 6 ), e.g. through a control valve 17 .
Between the beginning of the shed 6 and the main weft inserting nozzle 4 , a controlled cutting device 12 for cutting the weft thread 2 is assigned to the path of the weft thread 2 , e.g., suitable scissors are arranged there.
Behind the shed 6 a weft 5 arrival sensor 13 , also known as a weft stop motion, is assigned to the path of the weft thread 2 /weft 5 . The sensor 13 is connected to the device 11 for controlling weft insertion.
In front of the shed 6 a sensor 14 of the weft metering device is assigned to the path of the weft thread 2 /weft 5 , the sensor 14 being connected, e.g., directly or indirectly through an unillustrated control device of the machine to the device 11 for controlling weft insertion.
After being inserted through the shed 6, the weft 5 is carried by a beat-up mechanism (not shown) to the fell of the fabric 15 being formed.
A sensor 18 of revolutions of the main shaft 19 of the machine is connected to the device 11 for controlling weft insertion.
The invention is based on the fact that the movement of the weft 5 in the shed 6 is influenced by random phenomena which can be divided into several groups:

1. unevenness of the weft 5 properties, which is manifested by the fluctuations in the values of the mass parameters (fineness); aerodynamic characteristics and weft 5 parameters due to its lubrication (coefficient of friction and adhesion);
2. irregularities in the function of the weft insertion device, when the reaction time of the individual electromagnetic valves 16 , 17 and aerodynamic characteristics of the nozzles 4 , 8 alter with time and wear, causing changes in the air flow rates, as well as changes in the mechanical properties of the weft metering device 3 . Similarly, the aerodynamic characteristics of the weaving reed also change due to the wear of the weaving reed;
3. the weft 5 itself is during the movement through the shed 6 or through the weft inserting channel exposed to the effects of random phenomena, such as collisions with the walls of the channel, or with reed dents, or collisions with warp threads; furthermore, the weft 5 shape is not ideal during the insertion to the shed 6 and varies in the individual weft insertions, which naturally results in changes in the aerodynamic characteristics of the weft.

Parameter fluctuations in the first group of random variables may occur with a period ranging from a few meters of the weft thread 2 to thousands of meters of the weft thread 2 . At a weaving speed of hundreds of weft insertions per minute for woven widths in the order of meters, these are changes with a period in the order of units of minutes. Parameter fluctuations in the second group are long-term, occurring in the order of days or weeks of three-shift operation. Finally, the third group represents variance between the individual weft insertions.
The above-described random character of the weft insertion manifests itself in the distribution of the arrival times of the individual wefts 5 within the time interval. This distribution can be described by the Poisson probability distribution, which can be replaced for the sake of simplicity by the Gaussian distribution. Thus, if we select a set n of the values of the weft 5 arrival times, it is possible to determine the average value of the weft 5 arrival times and the standard deviation from this mean value. The mean value of the weft 5 arrival times is in the case of the Gaussian distribution given by the average of the individual weft 5 arrival times and the statistical deviation σ is determined from this mean value in a known manner. Clearly, the statistics of the arrival times are recalculated continuously with each new weft insertion and are determined for the next insertion, which means that the values of the arrival times of the selected number of insertions are kept in the memory of the device 11 for controlling the weft insertion and after each new insertion the oldest value from this set of values is removed and replaced by the value of a new insertion. This ensures "running" recalculation of the statistics of the arrival times for the selected number n of the recent insertions.
If we apply rule 3 σ, we can assume that during the given interval determined by the mean value and the statistical deviation (for the Gaussian distribution), the next weft 5 will arrive at the weft stop motion with a certain probability p, e.g., for coverage factor k = 3 the probability is p = 0.9973, for coverage factor k = 4 the probability is p = 0.99994. The range of these values is in the device 11 for controlling weft insertion for practical reasons limited to the interval 0 - 20, but it is only a formal limit. In general, the value of coverage factor (k) may be any non-negative number and it is the choice of the operator which required coverage factor to use, but this is done either at the cost of reducing the system accuracy, or at the cost of increasing the consumption of air and energy. The probability values for coverage factor k = 3 to 4 correspond to the probability of failure of weft to arrive during normal operation. Of course, technical limitations must be also taken into account, i.e. the actual length of the weft insertion, or the length of one working cycle of the machine.
It is therefore possible to state that on the basis of the group n of the previous weft 5 insertions the course of the next weft insertion can be predicted with probability p and a certain coverage factor k. It is then possible to determine mathematically the most probable position of the weft 5 fell depending on the time during the operation. Also, it can be concluded (and proved by theoretical considerations) that for achieving stable movement of the weft 5 during weft insertion, it is sufficient if only the weft 5 fell is blown over by the relay nozzles 8 , that is to say that it is sufficient to open the electromagnetic valves 17 of only those relay nozzles 8 above which the weft 5 fell is currently moving. At the same time, however, it can be assumed that the deviation of the passage time of the fell of the particular weft 5 from the mean (the most probable) value increases linearly in the direction of the length of the weft insertion. Then it is possible to determine an interval from the motion equation of the weft 5 , when the fell of the particular weft 5 passes above the specific part of the shed, i.e. above the specific relay nozzle, with the desired probability p. The actual timing of the valves 17 of the individual sections 9 of the relay nozzles 8 is then such that the start (the opening of the valve 17 ) is determined by the time of the passage of the weft 5 fell above the first relay nozzle 8 in the section 9 connected to this valve 17 and the end (the closing of the valve 17 ) is determined by the time of the passage of the weft 5 fell above the last relay nozzle 8 in the section 9 connected to this valve 17 . The result of the whole process is that in order to optimize the timing of the relay nozzles 8 according to the present invention it is sufficient to monitor (calculate) the statistics of the arrival times of the individual successive wefts 5 and include these data into statistical calculations according to the respective selected distribution, e.g., the Poisson distribution or Gaussian distribution, which enables to determine with the required degree of probability the mean value of these times and the statistical deviation of these times, all this depending on the working cycles of the machine. The thus obtained mean value then directly determines the position of the interval of the engagement of the respective section 9 of the relay nozzles 8 relative to the angle of rotation of the main shaft of the machine, or relative to the timing diagram of the machine (fictitious timeline of the machine), and the statistical deviation of these values determines the length of this interval of the engagement, i.e. the moments of the start and the end of the engagement of the respective section 9 of the relay nozzles 8 depending on the angle of the rotation of the main shaft of the machine, or with respect to the timeline of the machine.
When changes occur in the arrival times during the machine operation, then with a suitably selected number n of arrival time values of successive weft 5 insertions used for the statistics of the weft arrival and for the control of weft insertion according to the present invention, preferably ranging from 2 to 100 weft insertions, the development of the statistical values (mean value, statistical deviation) calculated from this number of arrival times reacts in such a manner that the engagement of the individual sections 9 of the relay nozzles 8 during the next insertion is either extended or shortened, including a possible shift in the position of the mean value of this interval relative to the working cycle of the machine, thereby also shifting the start and end moments of the respective nozzle section 8 relative to the working cycle of the machine. Basically, however, the number n of arrival time values of successive weft 5 insertions used for the statistics of the weft arrival and for weft insertion control can be set by the machine operator even from values over 100. Preferably, the value between 2 and 100, or 99, is chosen for practical reasons and to simplify programming. Nevertheless, as is evident from the principle and the required characteristics of the system, this number n affects the speed of the reaction of the system to the changes in the quality of the weft insertion, and therefore it is determined by a period (number of weft insertions) of fluctuations of those parameters to which it is desirable to respond by adjusting the weft insertion.
The outcome of the process is the fact that the timing of the relay nozzles is adaptive and is always optimally set directly by the value statistically calculated for the set value of probability p and the position and the interval length of the engagement of each section 9 of the relay nozzles 8 , i.e. also both start and the end of the interval, is automatically and adaptively changed during the weaving process according to the statistics of the selected number n of the previous weft insertions.
As graphically depicted in Fig. 2, the Poisson (Gaussian) distribution curves R show how the engagement of each section 9 of the relay nozzles 8 is affected by the varying statistics of the arrival times. The angle of the working cycle of the machine is indicated on the x-axis and the length of the weft insertion is indicated on the y-axis, whereby the length of the weft insertion corresponds to the position and spacing of the individual sections 9 of the relay nozzles 8 , as can be seen from the following Fig. 3. Fig. 2 represents the dependence of the position of the weft 5 fell along the length of the weft insertion on the working cycle of the machine and also illustrates the influence of the statistical calculations on the setting of the timing of the relay nozzles 8 of the last section 9-n of the relay nozzles according to the present invention. From the curve S of the movement of the weft 5 fell along the length of the weft insertion, where the curve S is determined, e.g., by the time measurement performed by the sensor 14 of the weft metering device 3 , which measures the movement of the weft thread 2 during the previous weft insertions, it is possible to determine the time point when each individual respective relay nozzle 8 is engaged to support the insertion. It is evident from Fig. 3 when the individual sections 9 of the relay nozzles 8 should be engaged, since the whole section 9 must be engaged already at the time point when the weft 5 fell is above the first relay nozzle 8 and the whole section must be engaged for the whole period until the weft 5 fell passes above the last relay nozzle 8 of this section 9 .
It is obvious from Fig. 2 that according to the present invention if the weft arrival times 5 have lower "variance" in the values, then their distribution around the mean value is "denser" and the curve of the Gaussian distribution R1 is narrower and higher. The desired coverage factor k of probability p that the arrival time of the next weft 5 will fall to the area defined by this distribution R1 corresponds to the position of the start and the end of the engagement of the individual relay nozzles 8 of each section 9 of the relay nozzles (here, specifically, of the last section 9-n ). If the variance in the weft arrival times changes (e.g. due to any of the above-described influences), e.g., it increases, then the distribution of these weft arrival times 5 around the mean value is "thinner" and the curve of the Gaussian distribution R2 is therefore wider and lower. The desired coverage factor k of probability p that the arrival time of the next weft 5 will fall to the wider and lower distribution R2 then corresponds to a position of a wider interval of the engagement of the final section 9-n of the relay nozzles 8 , i.e. both the start and the end of this engagement of the last section 9-n of the relay nozzles 8 are further from the mean value and the interval of the engagement of the last section 9-n of the relay nozzles 8 is therefore longer.
This applies to all the sections 9 of the relay nozzles 8 along the weft insertion length. However, it is always the case that the moments of the start and the end of the engagement of each respective section 9 of the relay nozzles 8 and, therefore, also the length of their engagement, correspond to the current actual conditions of the weaving process on the respective machine, which are accurately determined by the statistics of the weft 5 arrival times in the previous weft insertions, whereby the moments of the start and the end and, therefore, also the length of the engagement of the individual sections 9 of the relay nozzles 8 , are adaptively and automatically adjusted on the basis of the statistics of the arrival times of a pre-determined number of the previous weft insertions and, consequently, the compressed air consumption and energy intensity are adaptively optimized in accordance with the current actual conditions on the machine.
It is obvious that this principle can be also used in a situation when each of the relay nozzles 8 is controlled independently, although it is clear that there is a certain minimum length of the weft 5 fell, which has to be blown over by the relay nozzles 8 , especially for greater woven widths, which might cause problems in terms of the correct setting of the position of the air flow exiting the relay nozzles 8 in relation to the weft insertion direction.
Rather from the psychological point of view for the human operator of the weaving machines equipped with the present invention, it is possible that to the time points and intervals determined by this adaptive timing of the relay nozzles 8 , or sections 9 of the relay nozzles 8 , is manually "added" a certain time period before and/or after the time period determined by the adaptive timing of the relay nozzles 8 , or sections 9 of the relay nozzles 8 , according to the present invention, as shown in Fig. 3, where the intervals determined by the adaptive timing of the relay nozzles 8 or sections 9 of the relay nozzles 8 according to the present invention are extended beyond the limits indicated by the lines -4σ and +4σ just by the above-mentioned value entered manually by the machine operator. Nevertheless, this interval extension is not necessary for the proper operation of the present invention.
It is apparent from the above-mentioned that the device 11 for controlling weft insertion is provided with means for monitoring the statistics of weft arrival times of a pre-determined number n of successive insertions and for determination of the mean value and the statistical deviation from the measured values of the insertion times n of weft threads 5 inserted successively and it is also provided with means for adaptive control of the timing of the relay nozzles 8 , or, more specifically, their sections 9 , according to the mean value and coverage factor k of probability p of the insertion while meeting the statistical deviation of the arrival times n of the successively inserted wefts 5 . The necessary means of the device 11 for controlling weft insertion are implemented either purely in software or by a combination of software and hardware.

Claims

A method of controlling of weft (5) insertion in a shed on an air-jet weaving machine, during which a weft (5) thread is during its passage through the shed acted upon by an auxiliary air flow from relay nozzles (8), whereby weft (5) arrival times are monitored and according to them parameters of the action of the auxiliary air flow from the relay nozzles (8) during the next insertion are adjusted, characterized in that the statistical mean value and the statistical deviation from this mean value is determined on the basis of the weft arrival times (5) during a number (n) of successive weft insertions for each section (9) of the relay nozzles (8) along the weft insertion length, whereby the mean value is used for setting the mean value of the interval of the engagement of each section (9) of the relay nozzles (8) to support insertion depending on the angle of the working cycle of the machine and the value of the statistical deviation is multiplied by coverage factor (k) of probability (p) of weft arrival and this multiplied value is used for setting the start and the end of the interval of the engagement of each section (9) of the relay nozzles (8) to support insertion depending on the angle of the working cycle of the machine, and so the moments of the start and the end, and therefore the length of the engagement of the individual sections (9) of the relay nozzles (8) are adaptively and automatically adjusted on the basis of the statistics of the weft arrival times of the determined number (n) of the previous insertions, which allows adaptive optimization of compressed air consumption and energy intensity in accordance with the current actual conditions on the machine.
The method according to claim 1, characterized in that the statistical mean value and the statistical deviation from this mean value is determined for each one of the relay nozzles (8), whereby the mean value is used for setting the mean value of the interval of the engagement of each of the relay nozzles (8) for supporting insertion depending on the angle of the working cycle of the machine and the value of the statistical deviation is multiplied by coverage factor (k) of probability (p) of weft arrival and this multiplied value is used for setting the start and the end of the interval of the engagement of each of the relay nozzles (8) for supporting insertion depending on the angle of the working cycle of the machine.
The method according to claim 1 or 2, characterized in that the statistical mean value is the average of the values and the statistical deviation is a standard deviation.
The method according to any of claims 1 to 3, characterized in that the number (n) of successive weft insertions can be selected by the operator, preferably in the range from 2 to 100 weft insertions.
The method according to any of claims 1 to 4, characterized in that coverage factor (k) of probability (p) of weft arrival can be selected by the machine operator, preferably from 3 to 4.
A weaving machine with a control system of weft insertion in a shed, which comprises a main picking nozzle (4) connected to a source (10) of compressed air and to a device (11) for controlling weft insertion, whereby the main weft inserting nozzle (4) is assigned to the beginning of the shed (6) and a weft (5) thread reserve inserted into the shed (6) is assigned to the main weft inserting nozzle (4), whereby along the length of the shed (6) are arranged relay nozzles (8), connected to a source (10) of compressed air and to the device (11) for controlling weft insertion and behind the shed (6) is provided a sensor (13) of weft arrival, which is connected to the device (11) for controlling weft insertion, to which a sensor (18) of the revolutions of the main shaft (19) of the machine is connected, characterized in that the device (11) for controlling weft insertion is provided with
- means for monitoring the statistics of weft arrival times of a pre-determined number n of successive weft insertions and

- means for the determination of the mean value and the statistical deviation for each section (9) of relay nozzles (8) or each relay nozzle (8) from the measured values of arrival times n of successively inserted wefts (5) and

- means for setting the mean value as the mean value of the interval of the engagement of each section (9) of the relay nozzles (8) to support insertion depending on the angle of the working cycle of the machine and

- means for multiplying the value of the statistical deviation by coverage factor (k) of probability (p) of weft arrival and using the multiplied value for setting the start and the end of the interval of the engagement of each section (9) of the relay nozzles (8) to support insertion depending on the angle of the working cycle of the machine, and so the moments of the start and the end, and

- means for adaptive and automatically adjustment of the length of the engagement of the individual sections (9) of the relay nozzles (8) on the basis of the statistics of the weft arrival times of the determined number (n) of the previous insertions, which allows adaptive optimization of compressed air consumption and energy intensity in accordance with the current actual conditions on the machine.