GB2034869A

GB2034869A - Method of, and apparatus for, drying tubular fabric

Info

Publication number: GB2034869A
Application number: GB7934343A
Authority: GB
Original assignee: Courtaulds PLC
Current assignee: Akzo Nobel UK PLC
Priority date: 1978-10-04
Filing date: 1979-10-03
Publication date: 1980-06-11
Also published as: GB2034869B

Abstract

A method of drying tubular fabric 1 in a continuous process includes the steps of squeezing part of the liquid content out of the fabric by passing the fabric between two or more pressure rollers 2, at least one of which is driven, subsequently passing the fabric through means 10 for applying suction to each part of the external periphery of the fabric tube at least at some time during passage of said part through the means 10, and then passing the fabric through a hot air dryer 12. The arrangement is such that a current of hot air and liquid vapour is created from the dryer 12 to the suction means 10 counter to the direction of fabric movement. <IMAGE>

Description

SPECIFICATION Method of, and apparatus for, drying tubular fabric The generally used method for drying tubular fabrics after bleaching, or dyeing, whether intermediate or final drying consists of the following sequence of steps: Feeding the fabric in rope form into a centrifugal rotary hydro extractor: Pulling out the fabric after extraction, still in rope form: Transferring the hydro extracted batch of fabric with a moisture content reduced, for example, to between 55% and 75% on the dry weight of the fabric, to equipment consisting usually of a plurality of machines which carry out the drying by the application of heat, for instance, by blowing hot air against the fabric to be dried; this operation being often combined with the regulation of the tube width with the aid of internal stretchers.

This method has a number of disadvantages.

Continuous production is not possible because of the batch operation of the centrifugal rotary hydro extractor. The pressure exerted on the fabric in rope form by the centrifugal forces during extraction causes creases in the fabric which may be sufficiently pronounced to cause faults in the finished fabric. Moisture extraction of the fabric is non-uniform depending on the position of the particular piece of fabric in the centrifuge.

It is possible to modify the method by eliminating the hdyrdo extraction and using a water mangle for squeezing out part of the moisture, leaving, for example, - depending on the type of mangle and the type of pressure roller surfaces used - a quantity of water equal to between 55% and 100% of the dry weight of the fabric. Such a procedure involves the transfer of the fabric from the mangle to the heated dryer thus retaining the batck working procedure with its disadvantages of additional labour and requiring more managerial effort in the manufacturing process.

Batch working is made necessary by the difference in throughput on a mangle and in a drying machine in a given length of time which means that one mangle can feed partially dried fabrics to two or more hot air dryers with individual throughputs lower than the mangle.

During the past 10 or 1 5 years changes and improvements have been introduced in the drying of tubular fabrics by considerably increasing the moisture evaporting capacity of the dryer. More recent developments in drying fabric have been described in British patent applications numbers 2004998A and 2002503A. The former specification descirbes a new method of vacuum extraction of liquid from tubular fabric in which the entire outside periphery of the fabric from which the liquid is to be extracted is surrounded by means for applying suction. The latter specification describes a method of suction extraction in which suction means as described in specification No.

2004998A are located ahead of the region where the fabric enters the dryer creating a counter current of hot air in the tubular fabric from the heated section of a hot air dryer to the tubular suction extraction device preceeding it.

The above new methods result in an increased throughput capacity of tubular fabric dryers. This provides the new possibility of designing a continuous drying operation carried out by: 1. a squeezing mangle, 2 a tubular suction extractor, 3 the application of heat to the fabric, for instance, by blowing hot air against it as it progresses through the dryer.

According to the invention, a method of drying fabric in tubular form includes the steps of; squeezing part of the liquid content out of the fabric by passing the fabric between two or more pressure rollers at least one of which is driven; subsequently passing the fabric through means for applying suction to each part of the external periphery of the fabric tube at least at some time during passage of said part through said means; then passing the fabric through a hot air dryer; the arrangement being such that a current of hot air and liquid vapour is created from the dryer to the suction means counter to the direction of fabric movement.

According to a further aspect of the invention, apparatus for drying fabric in tubular form in a continuous process includes means for squeezing part of the liquid content out of the fabric comprising two or more pressure rollers at least one of which is driven, means for applying suction to each part of the external periphery of the fabric at least at some time during the passage of said part through said means, and a hot air dryer, the arrangement being such that a current of hot air and liquid vapour is created in use from the dryer to the suction means counter to the direction of fabric movement.

The fabric may be passed over stretcher elements in the customary manner whilst it is being heat dried. The advantages of a drying machine comprising elements to carry out all three of the operations described above include the following: Elimination of the batch production method with its unavoidable production sequence complication and additional labour requirements.

Elimination of the hitherto preferred method of rotary hydro extraction requiring more additional labour, and the source of fabric faults caused by the centrifuging.

Savings in labour and a simplification in the organisation of production. Under favourable conditions only one production worker is required for the whole sequence of operations on mangle, in suction extraction, and in drying by hot air, including the regulation of the tubular width.

The invention will be further described, by way of example, with reference to the accompanying drawing, in which Figures 1 to 3 are schematic sectional views of three different embodiments of apparatus in accordance with the invention.

In the apparatus shown in Figure 1, tubular fabric 1 is subjected to a squeezing action in a mangle including suitable means, for instance internal stretchers 13, to ensure that the fabric enters the mangle in flattened tubular form and in a basically crease-free condition. The mangle shown comprises two rollers 2 arranged one above the other. A moderate pressure is achieved between the rollers by weight, or by pneumatic or hydraulic means and at least one of the rollers is driven. More than two pressure rollers may be provided.

The fabric proceeds into and through the mangle in a horizontal direction in the embodiment shown in Figure 1. The covering surfaces of one or both rollers 2 of the mangle may be made from traditional rubber type materials or from one of the more recently introduced composition materials. The surface of one of the rollers may be metallic.

The fabric proceeds from the rollers 2 around a partly counter balanced roller 3. The counter balancing can be carried out for instance by a counter weight 4, slidably adjustable on a lever arm 5. Fulcrum 6, ensures that roller 3 has a tendency to move downwards under the influence of that part of its weight which is not counter balanced. Downward movement of the roller 3 will occur if the mangle supplies more fabric than is taken up by subsequent elements of the apparatus, and this movement of the roller controls speed regulating means for the mangle, mechanically or electrically slowing it down. In the opposite case when the speed with which the fabric is taken up is higher than the speed with which the rollers 2 supply it, then roller 3, rising into a higher position, actuates the equipment increasing the speed of the mangle.This method of speed regulation in itself is known and widely used.

Figure 2 illustrates a different means for adapting the mangle speed to the speed of the subsequent elements of the apparatus. In Figure 2, a suitably partly counter balanced scray 7 has fabric 8 accumulated in it Guiding rods or a guiding ring 9 guide fabric away from the scray 8.

If a few folds of fabric length accumulate in the scray then it sinks round its fulcrum into a lower position causing the slowing down or temporary stopping of the mangle. If the length of fabric in the scray decreases then the scray swivels into a high position to speed up or re-start the mangle.

Fixed stops (not shown) limit the upwards and downwards movement of the scray. The fabric proceeds after passing through either of the two speed regulation means shown in Figures 1 and 2 into and through a tubular suction extractor 10, and over a stretcher 11 (shown only in Figure 1) to a hot air dryer 12. The fabric then proceeds in the direction of arrow A (Figure ) to a folding or rolling arrangement prior to despatch.

In the appartus of Figure 3, fabric 14 rises vertically, preferably around internal stretching means 13, between mangle type driven squeeze rollers 1 5. The fabric proceeds from here vertically, or along a suitably inclined reach 16, downwards around a speed regulating means like that of Figure 1 or Figure 2. The fabric continues then as in the apparatus of Figure 1 or Figure 2 to a tubular suction extractor 10, over stretcher 11, and through hot air dryer 12, to a folding or rolling arrangement.

The suction means 10 in any of the embodiments of the invention described above may have any one of the forms described in published UK patent application No. 2004998A.

The suction means 10 thus applies suction to each part of the external periphery of the fabric tube at least at some time during the passage of said part through said means. That is, although every part of the external periphery of a region of the fabric 1 has suction applied to it as said fabric passes through the means 10, suction may not be applied to all parts of the external periphery of the fabric region at the same time.

The hot air dryer 12 used in any of the embodiments of the invention described above may be of conventional construction. The presence of the stretcher 11 in each embodiment ensures that the arrangement is such that the suction means creates a current of hot air and liquid vapour from the dryer to the suction means counter to the direction of fabric movement when the apparatus is operated.

The mangle comprising rollers 2 or 1 5 in the embodiment of the invention described above squeezes out part of the liquid content from the fabric, a further proportion of the liquid content being removed by the suction means 10 and a further proportion by the dryer 12 in a continuous passage of the fabric through the apparatus.

In each of the embodiments described above, the tubular fabric in its passage from the suction means 10 to the hot air dryer 12 may be surrounded by a heat-insulated, tubular chamber, for example a chamber of the kind shown in Figure 1 A of published UK patent application No.

2002503A. By applying suction to the interior of this chamber, at its end adjacent to the suction means 10, a flow of hot air and liquid vapour is encouraged, both outside and within the tubular fabric, in the direction from the dryer 12 to the suction means 1 0.

Claims

1. A method of drying fabric in tubular form in a continuous process, the method including the steps of; squeezing part of the liquid content out of the fabric by passing the fabric between two or more pressure rollers at least one of which is driven; subsequently passing the fabric through means for applying suction to each part of the external periphery of the fabric tube at least at some time during passage of said part through said means; then passing the fabric through a hot air dryer; the arrangement being such that a current of hot air and liquid vapour is created from the dryer to the suction means counter to the direction of fabric movement.

2. A method according to claim 1 where in the speed of said driven pressure roller or rollers is synchronised with the speed of the fabric passing between the pressure rollers by means of a partly counter balanced swivelling roller.

3. A method according to claim 1 wherein the speed of said driven pressure roller or rollers is synchronised with the speed of the fabric passing between the pressure rollers by means of a partly counter balanced scray.

4. A method according to claim 1, 2 or 3 wherein there are two pressure rollers located one above the other to allow fabric to pass horizontally between them.

5. A method according to claim 1, 2 or 3 wherein there are two pressure rollers located side by side to allow fabric to pass vertically upward between them.

6. Apparatus for drying fabric in tubular form in a continuous process, the appartaus including means for squeezing part of the liquid content out of the fabric comprising two or more pressure rollers at least one of which is driven, means for applying suction to each part of the external periphery of the fabric at least at some time during the passage of said part through said means, and a hot air dryer, the arrangement being such that a current of hot air and liquid vapour is created in use from the dryer to the suction means counter to the direction of fabric movement.

7. Apparatus according to claim 6 including a partly counter balanced swivelling roller for synchronising the speed of said driven roller or rollers with the speed of the fabric passing between the pressure rollers.

8. Apparatus according to claim 6 including a partly counter balanced scray for synchronising the speed of said driven roller or rollers with the speed of the fabric passing between the pressure rollers.

9. Apparatus according to claim 6, 7 or 8 where there are two pressure rollers located one above the other to allow fabric to pass horizontally between them.

10. Apparatus according to claim 6, 7 or 8 where there are two pressure rollers located side by side to allow fabric to pass vertically upward between them.

11. A method of drying fabric in tubular form in a continuous process, the method being substantially as hereinbefore described with reference to Figure 1, 2 or 3 of the accompanying drawing.

12. Apparatus for drying fabric in tubular form in a continuous process, the apparatus being substantially as hereinbefore described with reference to Figure 1, 2 or 3 of the accompanying drawing.

13. Fabric whenever dried by the method or in the apparatus claimed in any one of the preceding claims.