EP0335833B1 - Method and apparatus for stretching a fabric in width - Google Patents

Description

The invention relates to a method for spreading a fabric web in a mercerizing machine according to the preamble of claim 1 and an apparatus for performing this method.

One method for controlling the passage of a web is e.g. known from the applicant's CH-PS-531 969. The instantaneous length of the fabric web between successive treatment stations or between the beginning and end of a group of treatment stations is measured in each case and deviations in this web length from a desired value are corrected by regulating tension regulating members between the stations concerned or in the group concerned. Above all, the speed of the web in the impregnation zone is compared with the speed of the web in the stabilization zone. In the known device, continuous goods management is provided, i.e. the material web is supported practically without interruption, and passed from one roller to the next with no free space in between. The transfer of the material web takes place practically in the area of the contact line of the two rollers. The purpose of such a guidance is that the web of material or web of fabric that is spread out through the machine cannot possibly collapse in width during the treatment.

The invention, on the other hand, is concerned with a method or with a mercerizing machine for carrying out the method, in which the fabric web is first guided in a tied manner and then fed to a stenter. It has shown, that in general in the case of mercerization processes and the various pretreatments, such as desizing, boiling and bleaching etc., the fabric web is warped in the longitudinal direction during transport through the system, which results in a corresponding increase in width, which is further increased by the mercerization process. This can be reduced by the bound web guide or by stretching in conventional tenter frames, but not entirely avoided. This also applies to the method according to EP-A-0 198 793 or CH-PS-531 969, since the speeds of the drives can only deviate from one another to a relatively small extent due to the continuous web guidance.

From US-A-4,022,574 a method for the treatment of knitted goods is known, in which the goods from the bound web guide via a stretching device, an arrangement in which the goods can shrink under pressure and a further stretching device is fed to a tenter. The transition between the roller arrangement and the stretching device is thus implemented in a complex and technically difficult manner by means of three intermediate stations. The process sequence and the device required for this are complex to manufacture and operate and additionally strain the goods.

The invention has for its object to provide an improved method and an apparatus for performing the method, in which the fabric web can be brought to the required width and length by the mercerizing process in the stenter, in order to then be stabilized and fixed. A stretching of the fabric web is to be achieved which is carried out evenly and gently and does not lead to center-edge differences in the number of warp threads, as is often the case with chain mercerizing machines. According to the invention, this object is achieved primarily by a method according to the characterizing part of claim 1 or by a device according to the characterizing part of claim 4.

The invention turns away from the existing expert opinion that the web of goods must be supported practically continuously. The invention even deliberately accepts the fact that there is a widening of the width due to the free, unbound fabric guidance. At the same time, however, the lower pull-off speed of the fabric web in the area of the tenter frame enables a much better spreading effect of the tenter frame itself. It is of course familiar to the person skilled in the art to achieve optimal width and length stretching by varying the speed difference. For this purpose, one width section and one section can be placed on the fabric web before the first treatment stage in an initial section Longitudinal dimension to be marked. The change in width and length during the course of the process can then be checked in order to optimize the speed difference, if necessary in individual steps.

The invention can be implemented particularly simply if the tenter frame drive is controlled with a first speed setpoint and if the drives of the treatment stations in front of the tenter frame are controlled with a second speed setpoint and are regulated in each case by a fabric tension controller at a drive speed that keeps the fabric tension constant. In the area of bound goods management, each individual treatment station or each group of treatment stations is controlled in a manner known per se by the adjustable second speed setpoint, which can be superimposed by the fabric tension control. Every change in the fabric tension leads to an adaptation of the drive speed, which in concrete terms can mean that nip rollers lying one behind the other have slightly different drive speeds with increasing stretch of the fabric web. It is essential for the function of the invention that the first speed setpoint for the tenter frame drive to reduce the fabric tension in the area of the tenter frame inlet can be set smaller than the second speed setpoint before the inlet of the tenter frame.

The desired fabric tension in spite of the reduced conveying speed can be achieved particularly advantageously if the fabric web is guided away from the tenter frame in bound fabric guidance, if the fabric tension is determined in the area of the tenter frame outlet and if the conveying speed of the fabric in the tenter frame is dependent on the first speed setpoint and the determined one Tissue tension is regulated. Due to the reducible conveying speed of the stenter, the fabric web can shorten what a gentle spreading accommodates. In order to maintain the width of the web after it has been spread, a stretch with a bonded fabric guide connects directly to the stenter. The removal from the stenter takes place with a predeterminable fabric tension, the speed of the stenter being corrected accordingly if the tension falls below or exceeds.

The regulation of the speed difference between the tensioning frame and the stretch of bound goods guidance can be carried out particularly precisely if a pull roller is provided at the end of the roller arrangement for the bound goods guidance and if the fabric web runs freely through the free stretch between the pulling roller and the entry into the tensioning frame. The take-off speed of the pulling roller and stenter inlet thus determine the speed difference to be set. The slower the tenter frame is driven compared to the conveying speed of the draw roller, the more the length and width of the fabric web can shrink in the area of the free path, which affects the stretching behavior, especially the spreading behavior of the fabric web in the tenter frame.

In practical implementation, it is particularly advantageous if the drive motors of the rollers of the treatment stations before and after the stenter can be controlled on the one hand by control loops to keep the tension in the fabric web constant and on the other hand by at least one device for delivering a first and a second setpoint. The first or the second setpoint determines the basic speed of the entire system before the stenter and after the stenter, the speed after the stenter usually being lower than the speed before the stenter. The control loops for the individual treatment stations also ensure that the tension in the tissue web is kept constant.

The setting of the deviating relative speeds before and after the stenter can be realized particularly advantageously if the device for delivering a first speed setpoint is connected directly to the control loops of the stenter or the drive motors connected to the stenter and to a multiplication device, and if the output of the Multiplying device the second setpoint output and is applied to the control loops of the drive motors upstream of the stenter. Obviously, the ratio of the two setpoints to one another and thus the speed difference at the stenter inlet can be adjusted by simply adjusting the multiplication device. The multiplication device can be e.g. Calibrate as a percentage of the deviation in speed or the length of the conveyed goods. The percentage of the deviation can be displayed on corresponding preselection and display devices.

Figur 1

Eine Mercerisiermaschine mit Spannrahmen und mit zugehörendem Funktionsschema für den elektrischen Antrieb,

Figur 2

die Mercerisiermaschine gemäss Figur 1 ohne den Antriebsteil,

Figur 3a

eine schematische Darstellung des Breitenverhaltens der Gewebebahn in ihrem Durchlauf durch die Behandlungsstationen gemäss Figur 2 und

Figur 3b

eine schematische Darstellung eines Längenverhaltens der Gewebebahn.

The invention is explained in more detail below in an exemplary embodiment with reference to the drawings. Show it:

Figure 1

A mercerizing machine with a clamping frame and with the associated functional diagram for the electric drive,

Figure 2

the mercerizing machine according to FIG. 1 without the drive part,

Figure 3a

is a schematic representation of the width behavior of the fabric web in its passage through the treatment stations according to Figure 2 and

Figure 3b

a schematic representation of a length behavior of the fabric web.

FIG. 1 shows a mercerizing machine 1 which is known per se in terms of structure, in which a fabric web 2 in a bound web guide passes successively through a hot impregnation zone 3, a cooling zone 4, an action zone 5 and a stabilization zone 6, the mercerized and stabilized fabric web 2 subsequently not in one more washing machine shown is washed and neutralized. The stabilization zone 6 consists of two sections, namely the spreader zone 7, formed by the tenter frame 8 and a subsequent roller zone 9. In the roller zone 9, the fabric web 2 is also guided in a bonded manner. In the stabilization zone 6, the fabric web 2 is sprayed in a known manner by means of spray tubes 10 with hot weak lye in countercurrent, leached and stabilized.

In the spreading zone 7, the fabric web 2 is brought into the desired width by means of a tensioning frame 8 and, in such a spread out manner, is transferred to the roller zone 9.

In the present example, the clamping frame 8 is a needle clamping frame. In principle, however, other types of stenter frames or spreader devices are also conceivable. The tensioning frame 8 therefore has the task of bringing the fabric web 2 to the desired width and to ensure the stabilization of this width by the leaching.

The desired length of the fabric web 2 is only taken into account as a result of the change in width. The change in width and length of the fabric web 2 during the treatment can, as stated, be checked by marking the raw fabric and comparing the dimensions accordingly. In order to be able to change the stretching behavior in the tenter frame 8, the mercerizing machine 1 is divided into sections with fabric tension control 11.1 and 11.2 and a section with a so-called quotient control 12. This means that the drive motors of the treatment stations in the section of the quotient control can be operated at a lower conveying speed than in the previous section.

The area of the fabric tension control 11.1 comprises the hot impregnation zone 3 and the cooling zone 4. In contrast, the loading of the tenter frame 8 and the tenter frame 8 itself is operated by means of quotient control.

Known three-phase drives with frequency converters are used as the drive system for the various treatment stations (VSI, i.e. voltage source inverter). Crushes 13.1-13.5 are driven by drive motors (three-phase motors) 14.1-14.5, the speed of which is controlled by a first line setpoint 15.1 or a second line setpoint 15.2. The setpoints 15.1 and 15.2 are on lines 51 and 52 and are output from there to summing elements 16.1 to 16.4 and frequency converters 17.1 to 17.5.

To regulate the fabric tension, each of these drive motors 14.1 - 14.4 (with the exception of the guide motor 14.5) is assigned a fabric tension control roller 18.1 - 18.4, the deflection position of which is recorded in a known manner via a sensor (not shown) and a deflection angle calculator 19.1 - 19.4. In the summing elements 16.1-16.4, the feedback signals emitted by the computers 19.1-19.4 are superimposed on the first and second setpoints applied via line 51 and 52, respectively, in accordance with the deflection of the associated fabric tension regulator roller 18.1-18.4. In this manner, which is known per se, it is achieved that the transport of the fabric web through the hot impregnation zone 3, the cooling zone 4, the action zone 5 and the roller zone 9 takes place on the basis of the specified target values 15.1 - 15.2, taking into account the superimposed return values of the computers 19.1 - 19.4, that the train in the fabric web 2 is kept constant.

The fabric tension regulator rollers 18.1-18.4 are arranged in a known manner in such a way that even with different roller deflections, a bound fabric guidance and uniform fabric tension are always guaranteed. Such arrangements are state of the art.

As shown schematically in FIG. 1, the first setpoint 15.1 is set on a preselection device 20.1 and connected to line 51 via a voltmeter 21 used for the display. The voltmeter 21 is calibrated to the speed of the treatment stations or the fabric web 2 corresponding to the setpoint 15.1.

The line 51 passes the first setpoint 15.1 to a multiplier 23, the output of which passes the second setpoint 15.2 to the line 52. The multiplication factor of the multiplier 23 is adjustable in a known manner and it is therefore connected to a second preselection device 20.2 via a% display device 22. If the preselection device 20.2 is set to the value zero, the output of the multiplier 23 corresponds to the input, i.e. that the second setpoint on line 52 would correspond to the first setpoint on line 51. Changing the input on the preselection device 20.2 leads to a change in the multiplication factor and thus to an increase in the second setpoint value 15.2 output at the output of the multiplier 23 compared to the first setpoint value 15.1 present at the input. Increasing the setpoint 15.1 causes the summation elements 16.1 to 16.3 and 30 to be fed with a higher speed setpoint, which means that the transport of goods in the area of the hot impregnation zone 3, the cooling zone 4 and the exposure zone 5 is accelerated.

The tenter frame 8 is driven by a tenter frame drive 24 and a drive motor 25. A tension roller 26 is provided in front of the stenter, which is driven by a drive motor 27 is driven. The drive motor 25 is connected via a summing element 28 and a frequency converter 29, the summing element 28 being connected to the line 51 via a second multiplier 41, that is to say fed by the first setpoint 15.1. The drive motor 27 is fed by the frequency converter 31, which is connected to the summing element 30, which is fed by the line 52, ie by the second setpoint 15.2. The speed of the pull roller 26 is thus fed by the second setpoint (after the multiplier 23), while the speed of the drive motor 25 for the tenter frame 8 is determined by the first setpoint 15.1.

In the free path 32 between the pull roller 26 and the inlet of the tenter frame 8, a drop in the conveying speed can thus be generated by appropriate adjustment of the preselection device 20.2, with which the goods can shrink in a controlled manner before entering the tenter frame.

The transition from the area of fabric tension control 11.1 to section 12 with quotient control thus takes place in the free section 32, so that the fabric web 2 in the free section 32 can be transferred to the tenter frame 8 with excess length and with the correct length. Depending on the tension of the fabric web 2 in the free path 32, it is applied to the tensioning frame 8 more loosely or stretched. The needles of the tensioning frame 8 thus grip the fabric web with less or greater pretension, which greatly influences the stretching behavior of the goods. Subsequent tensioning to the desired width and stabilization with the spray tubes 10 allow the fabric web to be stabilized both in length and in width. As a result, after stabilization in the stabilization zone 9, the fabric web 2 effectively leaves the mercerizing machine 1 in the desired length and width.

Tachometers 35 and 33 and evaluation circuits 36 and 34 are also provided in the control loops of the drive motors 27 and 25, whereby a speed-dependent control behavior can be set.

The control in areas 11.1 and 11.2 in the areas of fabric tension control works in a known manner as follows: in the delivery of the fabric web faults in front of the pull roller 26, then the drive motor 14.3 of the pinch 13.3 is influenced accordingly via the previous fabric tension regulator roller 18.3 and the conveying speed of the fabric web 2 is increased or decreased accordingly; this leads - with a delay - to the same process in the fabric tension regulator roller 18.2 or 18.1 in front of it, which has the consequence that the conveying speed of the fabric web 2 in the action zone 5, the cooling zone 4 and the hot impregnation zone 5 adjusts so that the disruption that has occurred is compensated for and the fabric web 2 is conveyed under uniform tension.

The same control sequence applies to the squeeze 13.4, which is driven by the motor 14.4 and readjusted by the fabric tension regulator roller 18.4. In contrast, the pinch 13.5 is connected to the motor 14.5, which serves as a “master motor”. The speed of the motor 14.5 is determined exclusively by the first setpoint 15.1 fed in via line 51, so that any regulation for keeping the tension in the fabric web 2 constant or for setting the quotient regulation from the pinch 13.5 takes place “backwards”. Of course, it would also be conceivable to introduce a known "forward control" and e.g. to use the motor 14.1, or another motor, as the master motor.

To maintain the intended operating conditions, ie to maintain the percentage of tissue shrinkage set on the display device 22 by means of preselection device 20.2 and to include the tensioning frame 8 in the overall control loop, a tension regulator roller 38 is provided at the outlet of the tensioning frame 8. If there is a change in the tension in the fabric web 2, ie that too much or too little tissue is being conveyed by the tensioning frame 8, feedback signals are output to the multiplier 41 via an angle computer 39 and an evaluation circuit 40. These feedback signals are used via the summing elements 28, 30 both for readjustment of the drive motor 25 for the clamping frame 8 and of the drive motor 27 for the pull roller 26. As a result, an equal percentage change in the speed of the pull roller 26 and the tenter frame drive 24 is achieved in order to readjust the tension of the fabric web in the tenter frame outlet. Since both the pulling roller 26 and the tensioning frame drive 24 are adjusted, this readjustment does not change any existing speed difference in the free path 32 - the advance difference determined by the difference between the first setpoint 15.1 and the second setpoint 15.2 is also retained when readjusting.

As shown, a needle roller 37 in the outlet of the tensioning frame 8 guides it again bound to the fabric web, tension-dependent readjustment e.g. Via a fabric tension regulator roller 18.4, a computer 19.4, the summing element 16.4, the frequency converter 17.4 and the drive motor 14.4 can take place in the manner already described. Since the fabric web 2 is already largely stabilized by the intensive spraying by means of the spray tubes 10 when it leaves the tensioning frame 8, it is easily possible to transport it largely dimensionally stable through the bound guide in the roller zone 9.

2 shows the mercerizing machine 1 according to FIG. 1 identically. For the sake of clarity, only the most important reference numerals are shown and the electrical circuit has been omitted.

FIG. 3a shows schematically how the fabric width of the fabric web 2 can behave as it passes through the mercerizing machine 1. 63 denotes the fabric width, 64 a set target width and 65 the respective actual width. As shown schematically in the diagram, there is already a substantial loss of width when the fabric web 2 enters the mercerizing machine 1. This results from the impregnation of the goods with liquid media and from the fabric draw during transport through various pretreatment stages. The width loss increases somewhat in zones 3, 4 and 5 with bound web guidance. After the pull roller 26 and in the area of the free path 32, the loss in width increases sharply. This results from the unbound, loose fabric guidance in this area. The fabric web 2 is then spread out in the spreading zone 7 in such a way that it leaves the tensioning frame 8 with an excessive amount. This excess is set because in the roller zone 9 a loss of width can still be expected until the final stabilization, or residual shrinkage can also occur in the final equipment due to the longitudinal tension on the fabric web 2.

FIG. 3b shows schematically how the fabric web 2 behaves with regard to its fabric length 66 (unit length) when it passes through the mercerizing machine 1. In FIG. 3b, 67 is a desired target tissue length and 68 is the respective actual tissue length.

As shown schematically, the fabric web 2 is already stretched through the pretreatment and enters the mercerizing machine with excess length. By specifying the corresponding tension value in the fabric zone 11, a reduction in length can occur even before the free path 32. In the area of the free path 32, the non-bound fabric guidance of the fabric web and the lead difference can then cause a strong difference Shorten to below the setpoint. Since a longitudinal stretching of the fabric web 2 can still take place during the passage through the roller zone 9 and possibly also through subsequent post-treatment processes, the goods are handed over at the exit of the tenter frame 8 with a small descent.

The changes in width and length of the fabric web in the free path 32 and in the clamping frame 8 can be adjusted in the manner described above by adjusting the preselection device 20.2 in individual cases to desired parameters. As a rule, the spreading behavior of the fabric web 2 in the tenter frame 8 is promoted the more, the more loosely the fabric web 2 is transferred in the free path 32.

Claims (9)

1. Method of width stretching of a fabric web (2) in a mercerizing machine (1), the fabric web (2) running through a treatment section formed by individually driven treatment stations or groups of such stations (3, 4, 5, 6, 7, 9), and the fabric web (2) first of all being led in positive web guidance through wet treatment zones (3, 4, 5) and after that being led to a stenter frame (8), the fabric web being led to the stenter frame directly from the region with positive web guidance, characterized in that the outlet speed of the fabric web (2) out of the region with positive web guidance (zones 3, 4, 5) and the outlet speed of the stenter frame (8) is adjusted, one in relation to the other, in such a way that the fabric web is led to the stenter frame at a higher speed than it is fed away from the stenter frame, and that the fabric web is guided unrestrained (free run 32) in between the region of positive web guidance and the stenter frame, so that a change in width and length can ensue in this region.
2. Method according to claim 1, characterized in that the stenter frame drive (24) is controlled with a first nominal speed value, and that the drive (14.1, 14.2, 14.3, 27) of the treatment stations before the stenter frame is controlled with a second nominal speed value, in each case controlled by fabric tension controllers (18.1, 19.1; 18.2, 19.2; 18.3, 19.3) at a drive speed which maintains constant tension of the fabric.
3. Method according to claim 2, characterized in that the fabric web is guided away from the stenter frame (8) with positive web guidance, that the fabric tension in the region of the stenter frame outlet is ascertained, and that the feed speed of the fabric web (2) in the stenter frame (8) is controlled dependent on the first nominal speed value and from the ascertained fabric tension.
4. Device for carrying out the method according to patent claim 1 with an arrangement of rollers for positive web guidance (zone 3, 4, 5) and a tensioning roller (26) before the inlet into the stenter frame (8), characterized in that, between the tensioning roller (26) and the inlet, the fabric web (2) runs unrestrained and directly to the stenter frame (8) via a free run (32) in which a change in width and length can ensue, and that the fabric web can be led to the stenter frame from the arrangement of rollers at a higher speed than it is fed away from the stenter frame.
5. Device according to claim 4, characterized in that the drive motors (14.1, 14.2, 14.3, 14.4) of the rollers (13.1, 13.2, 13.3, 13.4) of the treatment stations before and after the stenter frame (8) are able to be controlled, on the one hand, by control circuits (16.1- 16.4; 17.1-17.4; 18.1-18.4; 19.1-19.4) for maintainance of constant tension in the fabric web (2) and, on the other hand, by at least one device (20.1, 23) for delivery of a first and of a second nominal value (15.1, 15.2).
6. Device according to claim 5, characterized in that the device (20.1) for delivery of the first nominal speed value (15.1) is switched to the control circuit (28, 29, 33, 34) of the stenter frame drive (24), respectively to the control circuit (16.4, 17.4, 18.4, 19.4) of the drive motor (14.4) which is switched in accordance with the stenter frame (8) and also a signal multiplication device (23), and that the second nominal value (15.2) is delivered from the output of the multiplication device and is fed to the control circuits (16.1-16.3; 17.1-17.3; 18.1-18.3; 19.1-19.3; 30,31,35,36) of the drive motors which are pre-switched in relationship to the stenter frame (8).
7. Device according to claim 6, characterized in that the drive motor (25) for the stenter frame drive (24) possesses a control circuit with a sensor (38) for maintainance of the tension of the fabric web (2) at the outlet from the stenter frame.
8. Device according to claim 7, characterized in that the comparison device (28) of the control circuit (28, 29, 33, 34) for the stenter frame drive is connected to the device (20.1) for delivery of the first nominal value.
9. Device according to one of the claims 4 to 8, characterized in that the drive motor (27) for the tension roller (26) and the drive motor (25) for the stenter frame drive (24) each possess a control circuit (30, 31, 35, 36 respectively 28, 29, 33, 34), and that a sensor and feedback arrangement (38, 39, 40, 41) is allocated to both control circuits together, for the proportional adjustment of the corresponding drive speeds when tension fluctuations arise at the outlet of the stenter frame (8).

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