Background
In the textile industry, it is very important to aim at a processing stage called fabric shrinkage, the purpose of which is to make the fabric dimensionally stable and thus able to maintain its own dimensions in all successive production processes.
Currently, the best dimensional stability results are obtained with drum processing systems for fabrics.
This system requires the fabric to be inserted into a machine equipped with one or more slotted drums and subjected to a mechanical action resulting from the rotation of the drum, which rotates alternately clockwise and counterclockwise. The drum may be equipped with protruding wings to increase agitation of the fabric and the injection of hot air and steam for drying the fabric.
Thus, the drum system is a discontinuous processing system, although it has the advantage of ensuring soft hand and bulking the fabric, and the disadvantages of low throughput and high cost, especially for those who must process many rolls per day. In addition, it was confirmed that the fabric was tangled and formed distinct folds during the treatment.
In order to improve the softness and feel of the fabric, other machines known as tumblers are used which subject the fabric to a mechanical action of agitation and vibration, so as to compact the fibres and thus obtain a satisfactory shrinkage of the fabric.
Tumbling cylinders cause the fabric (whether wet or dry) to move at high speed with air jets that maintain the fabric and transport it cyclically between the ends of particular tubes. The fabric may also be pushed against one or more protruding elements (preferably grid-like) during or at the end of its process inside the pipe. In this manner, the tumbling cylinder allows for good dimensional stability as well as softness and bulk to be imparted to the fabric.
Industrial invention patent No.1374887 describes a tumbling cylinder in which the fabric to be treated is subjected to the vibrating action obtained by hot air jets produced by oscillating nozzles and the impact on a grid-like object on which the fabric is thrown at high speed in a duct for pneumatic conveyance.
Utility model No.202017000051242 describes a machine in which the fabric is moved without being subjected to tension due to the thrust exerted by the air directed onto the fabric from below upwards in an inverted U-shaped pneumatic conveying duct.
US4922567 describes a machine for continuously treating a fabric.
Disclosure of Invention
It has been found and is an object of the present invention: in order to obtain the best results for stabilizing the fabric, the following conditions must be guaranteed:
the fabric must be treated with a set and controlled value of humidity,
drying does not have to be carried out in a short time and without high processing temperatures,
all possible tensions must be eliminated during the processing of the fabric.
The scope of the present invention is to create a range of machines for treating various types of fabric which, by ensuring the conditions listed above, enable to obtain the optimum dimensional stability of the fabric and also a good hand feel in a stepwise continuous process.
The invention achieves this by means of a machine for the continuous treatment of fabrics, intended here to be described in claim 1 cited herein, comprising a first module for soaking the fabric in water and relaxing it, a second module for the controlled drying of the fabric to the point of reaching the set value of humidity and a third module consisting of a tumble cylinder for treating the fabric to the point of complete drying.
Further advantageous features are the subject of the dependent claims.
The machine thus makes it possible to complete all the stages of the shrinking treatment of the fabric in a stepwise continuous process, eliminating all the tensions to which the fabric is subjected during the discontinuous process. In fact, it is advantageous that the fabric inside the machine is moved by means of a motorized drum synchronized by means of a control unit which calculates and corrects each drawing variation by means of the feedback given by the fabric during its passage through the treatment module.
Furthermore, the proposed solution enables a significant improvement in the results that would be obtained in the treatment of fabrics in a traditional tumble drum, since the fabric is pre-dried while still not being drawn and the residual humidity is controlled, enabling the tumble drum to function under optimal conditions. In fact, the tumbling treatment of the fabric with a set residual humidity level makes it possible, on the one hand, to take into account the time necessary for the tumbling cylinder to provide the hand feel and, on the other hand, to not increase the inertia level of the moving fabric, which would prevent the fabric from reaching its main purpose, i.e. the near complete shrinkage of the fabric.
Detailed Description
With reference to fig. 1, the machine according to the invention is essentially made of a module 1 for soaking the fabric, a module 2 for controlled partial drying of the fabric and a tumble drum 3, connected together and equipped with a feed system to continuously treat the fabric 20.
The feeding system designed to introduce the fabric 20 into the machine is preferably composed of an idle reel or drum 5 and a motorized reel or drum 25, the idle reel or drum 5 and the motorized reel or drum 25 cooperating with a set of stretching and tensioning rollers 18, so that the fabric 20 can be picked up from the trolley 4 and transferred to the inside of the module 1 of the machine in a wide and taut attitude.
Downstream of the drum 25, it may be useful to install a pair of photocells 21 to control the alignment of the fabric 20.
The module 1 for soaking fabrics consists essentially of a tank 7, the tank 7 being designed to contain the bath, equipped in a known manner with ducts with inlet and outlet valves and with a bath recirculation system (not illustrated in the figures). Preferably, a series of two or more nozzles 19 are arranged above the tank 7.
Near the area where the fabric 20 enters the slot 7, a slider 6 or equivalent means is installed to promote the formation of small uniform and regular folds.
Preferably, the tank 7 is equipped with a conveyor belt 8 in the form of a grid, the conveyor belt 8 being designed to prevent the folds formed in the fabric 20 from being excessively immersed in the bath. The conveyor belt 8 is also configured in such a way as to facilitate the gradual extraction of the fabric from the tank 7.
Near the area where the fabric 20 is lifted from the tank 7, the stylus 9 and the pair of pressing cylinders 10, 10' are preferably mounted with adjustable pressure.
In order to introduce the fabric 20 inside the module 2 and to advance the fabric 20, the feeding system consists of: a motorized wheel or drum 26 that cooperates with the drum 10, which is also motorized; and a pair of opposed belts 11 and 11' for receiving small folds of fabric 20.
Usefully, the belt 11 can be equipped with a chain of needles or be replaced by a chain of needles of known type, depending on the fabric to be treated.
The module 2 for the controlled partial drying of the fabric consists of two opposite rectilinear ventilation boxes 12 and 12', the ventilation boxes 12 and 12' being connected to a heating and air supply unit not illustrated in the figures. The ventilation boxes 12 and 12' constituting the rows are preferably arranged in offset positions along the path of travel of the fabrics inside the dryer 2.
A tumble drum 3 of known type, schematically indicated in the figures, is installed downstream of dryer 2 to receive the fabric treated therein.
Near the inlet of the tumble drum 3 there is a probe 22, the probe 22 being designed to detect the humidity or temperature of the fabric 20 leaving the dryer 2. Preferably, probe 22 transmits the detected values to the machine control unit.
The tumbling cylinder 3 essentially comprises a duct 15, the duct 15 being designed for pneumatic transport of the fabric between the two tanks 13 and 14, these two tanks being preferably equipped with a weighing system which collects alternately the fabric entering and exiting said duct 15. It is equipped in a known manner with an air supply duct which communicates with a ventilation and supply unit not shown in the figures.
In the example provided, the duct 15 is of the type equipped with two pairs of mobile shutters (shetter) 27 and 28 in the vicinity of the inlet, the mobile shutters 27 and 28 making it possible to move the fabric without tension, solely due to the thrust provided by the air directed onto the fabric from below upwards, as described in utility patent No.202017000051242, when the mobile shutters 27 and 28 are activated alternately.
Depending on the fabric being processed and on the desired shrinkage to be obtained, the tumbling cylinder 3 can usefully be of the known type with air moving under pure thrust without impact on the grid, of the type with more pronounced air movement and with variable subsequent thrust against the grid to obtain a stronger feel without in any case interfering with the shrinkage effect of the fabric, as described, for example, in the industrial patent No. 1374887.
The tumble cylinder 3 can in any case be of a different type, but is designed to treat the fabric without drawing it until it is completely dry.
Downstream of tumble drum 3, a conveyor belt 24 is mounted, conveyor belt 24 being driven by motorized roller 16 to deliver the fabric to cross-folder device 23.
The following functions.
Loading of the machine occurs in a known manner by sewing the head of the fabric 20 into the cloth of the drawing-in machine completing the path from the trolley 4 through the modules 1, 2 and 3 of the machine to the cross-folder device 23.
The fabric 20 arranged folded in the trolley 4 is picked up using a feed system comprising drums 5, 25 and introduced into the infusion module 1 through the drum 18, the fabric 20 being stretched and tensioned in the drum 18 over the entire length, including the selvedge.
After intercepting the slide 6, which promotes the formation of small folds in a uniform and regular manner, the fabric 20 reaches the mesh belt 8 and is introduced into the bath in the tank 7.
The fabric 20 will then be sprayed and carried by the mesh belt 8 until it reaches the synchronization device or stylus 9.
Depending on the type of fabric to be treated, the machine enables the folding of the fabric 20 to float on water or simply be transported by the belt 8 and wetted exclusively by a series of nozzles 19 arranged above it.
The machine advantageously uses a mesh conveyor belt 8 to prevent the folds in the fabric 20 from being excessively immersed in water and to be able to arrange the folds evenly.
Another purpose of the belts 8 is to carry the folds during the floating phase, so as to be able to take them out of the water step by step and bring them into contact with the synchronization means 9.
During this last phase of the fabric path in the module 1, the fabric 20 starts to gradually lose excess water before reaching the pressurized cylinders 10, 10'.
The feeler pin 9 can synchronize the speed of the belt 8 with the pressure cylinders 10, 10' and still arrange the fabric on the conveyor belt 11 of the dryer 2 in perfect synchronism, so as to feed it in excess by a percentage set by the operator.
The conveyor belts 11, 11' carry the fabric in a loose manner and therefore without any tension to the rockers 13 of the tumble cylinder 3.
The probe 22 can be of the type designed to directly detect the residual moisture of the fabric leaving the module 2, but preferably, due to the measurement limitations of the moisture detector, the probe 22 is of the type designed to detect the temperature of the fabric leaving the module 2 for greater accuracy. The value detected by probe 22 is sent to the control unit which verifies whether it corresponds to the desired set value, based on the fabric to be treated and on the desired result, so as to optimize the functioning of the tumbling cylinder 3.
The fabric 20 enters the tumbling cylinder 3 and is then arranged alternately in the collection tanks 13 and 14, as known, with small folds, thanks only to the thrust due to the direct air blown onto it from below upwards, thus obtaining an effective but non-invasive result on the fibres.
The change from one tank to the other is determined according to the values detected by the weighing devices connected to the tanks 13 and 14, but the machine may also be provided with other types of sensors, for example weighing cells.
The speed of the fabric can be adjusted by varying the air flow inside the duct 15 based on the weight of the fabric, the type of fabric to be treated and the desired result, according to algorithms known to those skilled in the art.
Upon leaving tumble drum 3, fabric 20 conveyed by belt 24 is arranged folded in trolley 17.
A control unit (not illustrated in the figures) equipped with a command interface thus enables the setting of machine operating parameters and the processing of the data detected by the sensors installed in the machine, and the appropriate corrective interventions.
In particular, for each type of fabric, the time and temperature of the treatment are set on the basis of the samples, so as to obtain a value of residual humidity that enables the tumbling cylinder 3 to operate under optimal conditions and to obtain optimal results.
In the case of a machine using a probe 22 that detects the temperature of the fabric, instead of the humidity, for greater precision, weighing is performed on a test sample of the fabric to determine the relationship between the temperature of the fabric and the residual humidity.
During the treatment of the fabric 20, the control means can vary the speed of advance of the fabric passing inside the modules 1 and 2, based on the value detected by the probe 22, so as to command the fabric feeding system for the purpose of increasing or decreasing the fabric treatment time in the dryer 2 and therefore the slack in the tank 7.
The movement of the belt and/or chain 11 is controlled by a control unit which synchronizes the speed with the rotation of the pressing cylinder 10, so that the fabric 20 is loosely arranged on the belt and/or chain 11, so as to be overfed by a percentage set by the operator.
Thus, according to the invention, the machine makes it possible to obtain very close to zero shrinkage and dimensional stability of the treated fabric both in width (weft) and in length (warp), since the fabric can be treated step by humidity treatment and without being subjected to any tension, with preset controllable values of drying time and processing temperature.
Although the invention has been illustrated with reference to a preferred construction, the invention is intended to be extended to cover arrangements providing equivalent utility.