GB2303382A - Continuous immersion dyeing method and apparatus - Google Patents

Description

IMMERSION DYEING METHOD AND APPARATUS The invention relates to treatment of textile material by immersion in a process liquid.

It is known in textile dyeing technology that textile material in rope or web form can be dyed in an aqueous solution of dyestuff at an appropriate temperature. The textile material is wholly or intermittently immersed in a process liquid during a dyeing cycle and there is relative motion between the textile material and the process liquid so that an even exchange of colour of the textile material is obtained.

If the textile material is to be dyed with intermittent immersion in the process liquid, the dyeing apparatus can have a kier which serves as a container containing the process liquid at a low position of the apparatus as well as a storage chamber for the textile material.

The process liquid is transported by a circulation pump to a nozzle or venturi device located at a position higher than the bottom of the kier such that the textile material can be immersed in the process liquid inside the nozzle or the venturi device. The textile material is lifted up to a position higher than the nozzle or the venturi device by a lifting roller and is delivered down into the nozzle or the venturi device such that the textile material is completely immersed in the process liquid. After the textile material passes through the nozzle or the venturi device the process liquid and textile material are returned to the kier. There is very little relative motion between the textile material and the process liquid at the bottom of the kier thereby little colour exchange is possible.

Problems arising with such known dyeing apparatus are the need for a relatively high textile material to process liquid ratio, which is generally known as the liquor ratio, and unwanted pile generated on the surface of the textile material in rope or web form and transported by rollers. A deficiency associated with transporting rollers is the introduction of tension into the textile material extending between the transporting rollers, and between one roller and the nozzle or the venturi device, which results in high shrinkage rate. The use of a nozzle or venturi device give rise to the generation of pile on the surface of the textile material.

It is advantageous so to design the dyeing apparatus that the liquor ratio is as low as possible, there is minimum generation of pile on the surface of the textile material and there is the minimum amount of shrinkage.

The difficulty in obtaining a low liquor ratio has its origins in the manner of separating the process liquid from the textile material, and effectively collecting and transporting the process liquid so that relative motion between the process liquid and the textile material can be maintained. To reduce the pile on the surface of the textile material, the impinging effect of the process liquid by the nozzle or venturi device has to be eliminated.

According to one aspect of the invention there is provided a method of treating textile material in rope or web form by immersion in a circulating process liquid contained in an immersion chamber within a kier of a dyeing apparatus, in which the textile material is loaded into the kier and is kept in endless circulation until completion of the treatment, wherein the endless circulation of the textile material is effected by first and second rollers driven individually and respectively by first and second electric motors whose speeds are controlled respectively by first and second frequency inverters, the speeds of which are preset and differentiated at a constant value.

According to another aspect of the invention there is provided immersion dyeing apparatus for treating textile material in rope or web form by immersion in a circulating process liquid comprising an immersion chamber within a kier, into which kier textile material can be loaded so as to be in an endless strip therein, first and second rollers to transport the textile material within the kier in endless circulation, first and second electric motors to drive the first and second rollers respectively and first and second frequency inverters to control the speeds of the first and second motors respectively, the speeds of the frequency inverters being preset and differentiated at a constant value.

Such a method and apparatus can solve the problem of separating the process liquid from the textile material and transporting the process liquid to maintain the relative motion between the process liquid and the textile material.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figure 1 is a schematic diagram showing an embodiment of immersion dyeing apparatus according to the invention with a heat exchanger located outside the apparatus; Figure 2 is a block diagram showing a control and sensing means of the immersion dyeing apparatus; Figure 3 is a schematic diagram showing separation of the textile material and process liquid; and Figure 4 is a schematic cutaway perspective view of an embodiment of immersion dyeing apparatus according to the invention with a heat exchanger located inside the apparatus.

Referring to the drawings. Figure 1 shows a schematic cross section of dyeing apparatus into a kier 15 of which textile material.

which may be for example several hundred metres in length, is loaded through a loading door 13. The kier 15 has a top 7 and an internal guiding plate 9. The ends of the textile material are sewn together to form an endless loop. The textile material is transported by a roller 1 through a channel 2 and passed under a roller 5 within an immersion chamber 4. A roller 8 pulls the textile material 3 from the immersion chamber 4 and drops the textile material into the kier 15.

The textile material 3 absorbs process liquid in the immersion chamber 4. When the textile material drops from the roller 8. it engages a water separator 6. The process liquid 2 is separated from the textile material 3 by the water separator 6 and is collected by a collector 14. By means of a pump 11 the process liquid 12 is transported through an external heat exchanger 10 back to the immersion chamber 4.

Referring to Figure 2, the roller 1 and the roller 8 are each driven individually by a respective electric motor 17, 29.

The roller 1 is driven via a shaft 16 by the electric motor 17.

The speed of the motor 17 is adjustable by a frequency inverter 19 via a connection 18. The setting frequency of the frequency inverter 19 is regulated by a regulator 26, which is a computer, via a signal comparator 21. The signal from the regulator 26 is sent via a connection 22 to the comparator 21 which compares the signal from the frequency inverter 19 and outputs another signal to the frequency inverter 19 until the output frequency from the frequency inverter 19 to the electric motor 17 is correct. The roller 1 will run at the set speed until there are changes to the regulator 26.

A roller 5 is a driven roller. Textile material 3 passing under the roller 5 exerts an upward force on the roller 5. The force is picked up by a sensor 24 via a shaft 23 and a signal is sent along a connection 25 to the regulator 26. The regulator 26 will send a signal along a connection 34 to a comparator 33 which, depending upon the magnitude of the signal received, sends a regulated signal along a connection 35 to a frequency inverter 31. The speed of the electric motor 29 is thus adjusted by the frequency inverter 31 via a connection 30. The electric motor 29 drives the roller 8 via a shaft 28 to pull the textile material 3 from the roller 5. A signal is fed back through a connection 32 to the comparator 33 and is compared with a signal received on a connection 34 from the regulator 26.An adjusted signal is then sent via the connection 35 to the frequency inverter 31 to regulate the output frequency to the electric motor 29 and a signal is sent via a connection 27 to the regulator 26 to complete the control loop to achieve a synchronized speed at the roller 1 and the roller 8.

When the tension on the roller 5 is reduced by obtaining synchronized speeds of the roller 1 and the roller 8. the signal picked up by the sensor 24 is decreased and thereby the magnitude of the signal sent by the regulator 26 to the comparator 33 is also reduced and eventually stabilized to within the set deviation.

By monitoring the speed differential between the rollers 1 and 8 via the frequency inverters 17 and 29. the tension exerted onto the textile material 3 is thereby monitored and the shrinkage is kept under control.

Referring to Figure 3, a separator 37 is an array of tubes 38 supporting the textile material 3 away from the surface of the kier 15.

The tubes 38 are spaced at a suitable pitch which can be found by experiment.

The amount of the process liquid absorbed by and to be separated from the textile material 3 depends on the force applied to the textile material 3. The spacing of the tubes 38 of the separator 37 prevents the textile material 3 sagging between the tubes 38 of the separator 37. The dead weight of the sagged textile material 3 between the tubes 38 of the separator 37 exerts a tension which squeezes out the liquid held by capillary effect between the fibres of the textile material 3.

It is well known from physics that there is always frictional force between any two elements. It also applies to the textile material and the tube surface of the separator 37. The frictional force depends on the type of fibre forming the textile material, the unit weight of textile material per unit width of the tube spacing of the separator and the surface texture of the tubes of the separator.

The relationship between the type of fibre of the textile material, the surface texture of the tubes of the separator, the unit weight of the textile material and the amount of water that can be separated can be established by experiment.

In Figure 4 the same reference numerals are used for components which are similar to those shown in Figure 1. A heat exchanger 40 is provided internally, to replace the heat exchanger 10 of Figure 1, and is located above the roller 5.

Claims (10)

1. A method of treating textile material in rope or web form by immersion in a circulating process liquid contained in an immersion chamber within a kier of a dyeing apparatus, in which the textile material is loaded into the kier and is kept in endless circulation until completion of the treatment, wherein the endless circulation of the textile material is effected by first and second rollers driven individually and respectively by first and second electric motors whose speeds are controlled respectively by first and second frequency inverters, the speeds of which are preset and differentiated at a constant value.

2. A method according to claim 1, wherein, in the control of speed differential between the two rollers by the frequency inverters, the output frequency of the first frequency inverter to the first electric motor is set at constant by a regulator which sends a signal to a signal comparator, the output frequency of the second frequency inverter to the second electric motor is continuously controlled by a signal from a second signal comparator which compares a signal from the second frequency inverter, a signal from the second signal comparator is regulated by a signal from the regulator which picks up a signal from a sensor on a third roller to maintain the speed differential between the first and second rollers according to a preset value at the regulator.

3. A method according to claim 1, wherein a driven roller is connected to a sensor for transmitting the measured tension applied to the roller by the textile material, and the signal from the sensor is processed by the regulator for the continuous regulation of the output frequency of the second frequency inverter to the second electric motor to maintain a preset differential speed between the first and second rollers.

4. A method according to claim 1, including controlling the tension in the processed textile material, by the application of controlled speed differential between the rollers.

5. Immersion dyeing apparatus for treating textile material in rope or web form by immersion in a circulating process liquid comprising an immersion chamber within a kier, into which kier textile material can be loaded so as to be in an endless strip therein, first and second rollers to transport the textile material within the kier in endless circulation, first and second electric motors to drive the first and second rollers respectively and first and second frequency inverters to control the speeds of the first and second motors respectively, the speeds of the frequency inverters being preset and differentiated at a constant value.

6. Immersion dyeing apparatus according to claim 5, including a water separator at the bottom of the kier, comprising an array of tubes spaced at a designated pitch whereby process liquid contained in or absorbed by the textile material can be separated at the maximum efficiency.

7. Immersion dyeing apparatus according to claim 5 including an immersion chamber to be flooded with the process liquid and a roller with the textile material wrapped around its lower periphery.

8. Immersion dyeing apparatus according to claim 5 wherein the process liquid maintained for the treatment of the textile material is constant.

9. A method of treating textile material in rope or web form by immersion in a circulating process liquid as claimed in claim 1 and substantially as hereinbefore described.

10. Immersion dyeing apparatus substantially as hereinbefore described and illustrated with reference to the accompanying drawings.