Apparatus for the drying and heat-fixing of fabrics and the like by means of high-temperature air circulation within a tunnel with a plurality of curing chambers

Abstract

 Apparatus for the drying and/or heat-fixing of fabrics and the like by means of high-temperature air circulation within a curing tunnel (1) of the type having a plurality of isolated sections (2, 2a, 2b), provided with fans (11, 11a, 11b) and each divided into two chambers (5,5a), the upper ones (5a) whereof, which are crossed by the fabric (7), constituting the heating chambers, and the lowers ones (5) constituting the air recirculation chambers, with inflow of fresh air in the fabric entry area (6) and extraction in the output section (2b), said apparatus comprising adjustable means (19, 19a, 19b) for connection between the individual contiguous recirculation chambers, adapted to vary the geometry of said chambers so as to allow the individual fans (11, 11a, 11b) to aspirate part of the recirculation air from the preceding contiguous chamber and thus create a continuous aspiration moved in countercurrent with respect to the advancement of the fabric (7), said means for connection between the recirculation chambers being related to the flow rate of the final extraction fan (17), which in turn is controlled by a humidity control device, while an electronic device (23), based on microprocessors or the like, is provided to vary the volume of the air extracted as a function of the evaporate.

Description

[0001] The present invention relates to a continuous-cycle automated apparatus for the drying and heat-fixing of fabrics by means of forced circulation of high-temperature air, made to circulate by means of fans inside a curing tunnel through which the fabric is caused to continuously advance.

[0002] As is known, a drying and/or heat-fixing apparatus for fabrics is generally constituted by a parallelepipedal tunnel, divided into chambers or sections which are separated from one another, through which the fabric is caused to advance, horizontally, by means of chain conveyors or the like. Each section is divided into two chambers by a horizontal plane, the upper one being crossed by the fabric and containing devices for the distribution of the hot air on the fabric, while the lower one forms the recirculation and preheating chamber for the air originating from the upper drying chamber. Fans, placed in each upper chamber, blow hot air, distributing it uniformly on the entire fabric and simultaneously aspirate, from the lower chamber, the humid air originating from the upper chamber, which, after heating, is again blown onto the fabric.

[0003] Since part of the air which circulates in the chambers must be continuously renewed in order to prevent saturation, the apparatus is provided with an extraction device, normally an extraction fan, which aspirates air from the various curing chambers through a series of channels connected to said chambers.

[0004] In theory, a volume of air proportional to the water vapor produced in each section should be extracted from said section of the curing tunnel, and similarly a fresh-air inflow system should be provided in each section.

[0005] In order to adjust the amount of air to be extracted from each section according to the requirements of the process, automatic devices have been proposed which allow a continuous adjustment of the amount of air extracted, as a function of the average humidity concentration measured on the extraction fan; more recently, the method has been adopted of introducing the entire air refresh volume together with the humid fabric, arranging an extraction fan in the terminal chamber of the drying tunnel. This solution allows to achieve the maximum concentration of humidity in the last section of the tunnel, that is to say at the end of the drying process; in other words, this solution consists of introducing wet fabric and air into the fabric entry chamber and of extracting dried fabric and saturated air from the terminal section of the tunnel.

[0006] In order to achieve this, the extraction fan must have such a size as to be able to aspirate air from the fabric entry area, but not such as to aspirate air from the adjacent fabric output slot; in practice, however, the presence of a strong depression in the output section generates leakages of cold air through the fabric output slot, and these leakages of cold air create condensations, since they are originated by a hot and saturated air current which collides with the cold air draughts.

[0007] Therefore, in practice, even this approach is not acceptable.

[0008] The main object of the present invention is therefore to provide a fabric drying apparatus structured so as to eliminate the formation of condensations in the terminal section of the curing tunnel, and therefore such as to eliminate all the disadvantages featured by known devices, which use a single extraction fan arranged in the terminal part of the tunnel.

[0009] An object of the invention is to provide an apparatus of the above described type, having means for the automatic adjustment of the flow-rate of the extraction fan as a function of the evaporate, and for the conveyance of the airflow through the various chambers, thus preventing the onset of a depression in the terminal section connected to the extraction fan.

[0010] A further object is to provide an apparatus which is simple to produce and has a cost which is competitive with that of known apparata having a single extraction fan.

[0011] The above objects, as well as other objects which will become apparent hereinafter, are achieved by an apparatus for the drying and/or heat-fixing of fabrics and the like by means of high-temperature air circulation within a curing tunnel of the type having a plurality of separate sections, provided with fans and each divided into two chambers, the upper ones, which are crossed by the fabric, constituting the heating chambers, and the lowers ones constituting the air recirculation chambers, with inflow of fresh air in the fabric entry area and extraction in the output section, said apparatus comprising, according to the present invention, adjustable-aperture means for connection between the individual contiguous recirculation chambers, adapted to vary the geometry of said chambers so as to allow the individual fans to aspirate part of the recirculation air from the preceding contiguous chamber and thus create a continuous aspiration moved in countercurrent with respect to the advancement of the fabric, said means for connection between the recirculation chambers being related to the flow rate of the final extraction fan, which in turn is controlled by a humidity control device, while an electronic device, based on microprocessors or the like, is provided to vary the volume of the extracted air as a function of the evaporate.

[0012] More particularly, said means for connection between the contiguous recirculation chambers are constituted by at least one opening or port, provided in the vertical wall which divides said recirculation chambers, with which is associated a door, openable in a wing-like or similar manner, adapted to adjust the passage aperture of the air aspirated from each preceding chamber by the fan of the following one according to the flow-rate of the final extraction fan (exhauster), said doors being connected to one another and controlled by a motor reducer or the like with intervention programmed by means of said microprocessor device.

[0013] The invention is hereinafter described in greater detail according to a preferred embodiment, with reference to the accompanying drawings, given only by way of non-limitative example, wherein:

figure 1 is a schematic perspective view, in partial cross section, of a drying tunnel apparatus with a plurality of sections, provided according to the invention;

figure 2 is an also schematic cross section view along the line II-II of figure 1; and

figure 3 is a schematic top view of the apparatus of the preceding figures.

[0014] With reference to said figures, the drying apparatus is of the tunnel type with sections and fabric conveyance of a known kind, whereto the inventive concepts according to the present invention are applied.

[0015] A tunnel 1 is constituted by a parallelepipedal hollow body, extending lengthwise, with thermally insulated outer walls and internally divided into sections or compartments 2-­2a-2b etc. by means of vertical dividing walls 3-3a-3b; each section is divided into two superimposed chambers by means of horizontal walls 4-4a-4b etc. For the sake of greater clarity, figure 2 clearly shows the two superimposed chambers which are indicated by the numerals 5-5a. Horizontal slots 6-­6a-6b-6c etc. are provided at the upper chambers 4a in the vertical dividing walls 3-3a-3b etc., and are arranged in the same plane with respect to one another, and the fabric 7 to be dried is caused to advance through them by means of known conveyors of the chain type or the like (not shown); the fabric is introduced from one side and extracted from the opposite side of the tunnel 1.

[0016] Hot air distributors 8-8a-8b etc. are arranged in each upper chamber 5a of the various sections, and are constituted by substantially trapezoidal box-like bodies, arranged mutually side by side so as to leave between one another an interspace for the circulation of hot air also on their outside; each distributor, as shown by way of example and for the sake of convenience in only one section of the tunnel, is downwardly provided with holes 9 directed towards the underlying fabric; a similar assembly of distributors with trapezoidal bodies, arranged counterposed, is arranged below the fabric, as clearly shown in the figures.

[0017] The larger base of the distributors 8-8a-8c etc., both of the upper ones and of the counterposed ones, is connected to a chamber 10 in which a pair of fans 11-11a-11b etc., of the axial aspiration type, is arranged so as to aspirate, by means of ducts 12 and openings 13 provided in the horizontal walls 4-4a etc., air from the respective underlying chamber.

[0018] The lower recirculation chambers 5 are connected to the respective air inflow chambers 5a by means of an extractable filtering structure 14, and are provided with a heating device such as a burner 15; moreover, openings 16 on to the outside, adapted to allow, together with the fabric passage slot 6, the aspiration of the fresh replacement air, are provided in the first recirculation chamber (fabric entry).

[0019] Finally, an extraction fan 17 is provided at the top of the last section (2b) of the tunnel 1, and, in known embodiments, aspirates air and steam from the various sections of the tunnel by means of a series of channels, not shown.

[0020] As previously mentioned in the introductory part of this description, the presence of a single extraction fan and the introduction of the entire volume of replacement air together with the wet fabric creates a strong depression in the output section which generates undesired leakages of cold air through the output slot of the fabric, causing the formation of unacceptable condensations and drippings.

[0021] The present invention allows to avoid the formation of a strong depression in the final section of the tunnel by means of an adapted variation of the internal geometry of the recirculation chambers 5.

[0022] The adopted solution provides the arrangement, in the vertical walls 3-3a-3b etc. which divide the recirculation chambers 5, of an opening or window 18 and, respectively 18a, 18b, provided with a wing-like openable door 19 and, respectively, 19a-19b; all the doors are connected to one another by a rod or traction element 20, which protrudes in front of the tunnel (figure 1) and is subject to alternate axial movements by means of a motor reducer 21. By means of movements of the rod 20 it is possible to vary the aperture of the openings 18-18a-18b or rather to vary the load losses that the presence of the more or less open doors can create in the recirculation chamber.

[0023] The presence of said openings in fact allows the fans 11-11b etc., intended for the blowing-in of hot air onto the fabric, to modify the flow rate of the recirculation air in the various chambers and to achieve an aspiration, on the part of all the fans, moved in countercurrent with respect to the advancement of the fabric; this occurring since each aspirator, by virtue of the presence of the openings between the chambers, aspirates part of the recycling air from the preceding contiguous chambers.

[0024] The overall flow rate therefore follows a path which matches the advancement of the fabric and is adjusted by varying the position of the doors 19, that is to say the geometry of the individual recirculation chambers; the path of the air is indicated by the arrows A of figure 3.

[0025] The variation of the position of the doors is related to the flow-rate of the extraction fan 17 which is controlled by a known humidity control system.

[0026] Substantially, the intake of fresh air in the fabric entry region is due to the sum of the depressions created in the chambers by the individual circulation fans and not by the extraction fan alone, with the consequence that a slight pressure is created in the output region or section of the tunnel, preventing fresh air from leaking through the fabric output slot and therefore from creating condensation phenomena.

[0027] With this embodiment, the function of the extraction fan 17 is only to eliminate the air and the steam which the system draws into the final section of the tunnel.

[0028] The above described apparatus is furthermore provided with probes 22 for detecting the temperatures in the various sections and with an actuation and control device 23, of the microprocessor type or the like, connected to the motor variator 21 and to the extraction fan and programmed so as to vary the volume of evaporate (air + steam) as a function of the evaporate.

[0029] Naturally, in the practical embodiment, the invention described above is susceptible to modifications and variations, especially in the recirculation chamber geometry variation system, for example by adopting more openings and means equivalent to doors, without thereby abandoning the scope of the protection of the invention.

Claims

1. Apparatus for the drying and heat-fixing of fabrics and the like by means of high-temperature air circulation within a curing tunnel of the type having a plurality of isolated sections, provided with blower fans and divided into two superimposed chambers, the upper one whereof, crossed by the fabric, constituting the hot air blowing-in chamber, and the lower one constituting the recirculation chamber, with inflow of fresh air in the fabric entry area and extraction in the output section by means of a fan, characterized in that it comprises adjustable means for connection between the individual contiguous recirculation chambers, adapted to vary the geometry of said chambers so as to allow the individual fans to aspirate part of the recirculation air from the preceding contiguous chamber and thus create a continuous aspiration moved in countercurrent with respect to the advancement of the fabric, said means for connection between the recirculation chambers being related to the flow rate of the final extraction fan, which is in turn controlled by a humidity control device, while an electronic device, based on microprocessors or the like, is provided to vary the volume of the extracted air as a function of the evaporate.

2. Apparatus according to claim 1, characterized in that said means for connection between the contiguous recirculation chambers are constituted by at least one opening or port, provided in the vertical wall which divides the recirculation chambers, with which is associated an orientatable element substantially in the shape of a wing door, all the doors of the recirculation chambers being adjustable so as to relate the volume of recirculation air in the tunnel to the flow rate of the final extraction fan.

3. Apparatus according to claim 1, characterized in that said orientatable doors are mutually connected and orientated by a motor reducer with intervention programmed by means of said microprocessor device.

4. Apparatus according to claim 1, characterized in that said microprocessor device is connected to said motor variator, to the humidity detection system which actuates said extraction fan and to probes provided in every air blowing-in chamber for the control of the temperature of the in-blown hot air, so as to constantly vary the volume of extracted air as a function of the evaporate.

Drawing