The present invention relates to a process for drying and/or conditioning leathers or similar flexible laminar surfaces, especially tannery leathers, typically, although not exclusively, wet leathers which have just been retanned, dyed and greased, for example in a machine known in the leather industry as "drum", or leathers still partially moist which must be stabilized by means of a treatment known in the leather industry itself as "conditioning".

In detail, the flexible laminar surfaces machinable by means of the process of the invention comprise cattle leather, imitation leather, regenerated leather, leather, synthetic material, fabric and/or the like (with specific exclusion of paper).

The peculiar feature of the process of the invention consists in the fact that it allows the continuous advancement of the support frames loaded with leathers to be treated inside an operating drying tunnel even in the absence of operators who manage and control the operation thereof and are absent from the workstation for an extended period of time (conventionally, in the order of a couple of hours maximum), for example for a lunch break, due to an unexpected (however temporary) exit from the premises or for other reasons; this without therefore disadvantageously stopping the processing of the leathers (or of similar laminar surfaces) leaving some of them stationary inside the operating tunnel for an unspecified period of time, as it occurs in the prior art.

As known, in tannery industry, leathers drying (or desiccation) is a basic working that is typically performed as the central step of the whole leather production process (in which the leathers yet take on the connotation of semi-finished products) aiming to dry the leathers water excess stored in previous workings.

Before the drying process, the leathers have, in fact, already been subjected to at least chemical and mechanical processes, such as soaking, liming, fleshing, splitting, deliming, degreasing, tanning, retanning, shaving, dyeing and greasing, carried out in the appropriate and consolidated operating sequence thereof, and are presented as wet semi-finished products.

In the current state of the art, the drying process is carried out with various plant solutions, according to the type of leather and the final destination of the finished product: in this regard, for example, suspended drying or hanging, drying by nailing, drying by pasting, vacuum drying are mentioned.

Conditioning, on the other hand, is an operation by which the animal skin is kept in an environment at standard temperature (T) and relative humidity (RH) (for example, T = 20°C and RH = 65%) so as to reach a condition of balance with the environment and therefore carry out the desired mechanical processes with the necessary effectiveness and efficiency.

Essentially, a conventional plant for drying and/or conditioning leathers of the prior art (shown for example in EP 2904121 A1 and EP 3004400 A1 ) comprises an operating tunnel which mainly extends along a longitudinal direction and is provided with air conditioning devices, (such as, for example, fans of the axial type) and/or traction members (such as, for example, pneumatic members installed in the operating tunnel), adapted to act on the leathers so as to respectively dry and/or stretch them according to predetermined treatment, conditioning and/or tensioning cycles.

A known drying and/or conditioning plant further comprises a plurality of support frames, each of which stably, temporarily and removably accommodates, on at least one of the two side faces thereof, at least one leather, so as to keep it stretched, as well as movement means, operatively connected to the support frames to convey them along the aforesaid longitudinal direction according to a prefixed speed, inside the operating tunnel, where the drying and/or conditioning of the leathers occurs, and outside the operating tunnel itself, where an operator, but much more often at least a couple of operators, unload such dried and/or conditioned leathers of a given processing cycle and load other leathers to be dried and/or conditioned in the subsequent processing cycle.

Generally, for each support frame complete or loaded with leathers, to be treated by drying and/or conditioning, which enters the operating tunnel, there is another one which comes out of the operating tunnel itself, complete with leathers yet treated: it is often the push exerted by the incoming support frame on the pack of support frames already inside the operating tunnel which causes the exit from the opposite side of the support frame loaded with leathers yet treated. In particular, generally, the operators couple the leathers by nailing both side faces of the respective support frames which, immediately afterwards, are automatically conveyed, one by one, inside the operating tunnel of the plant where the drying and/or conditioning thereof are obtained by suitably varying and modulating, according to the pre-selected settings, the internal temperature and humidity conditions along the longitudinal extension of the operating tunnel.

Before coupling them stably to the support frames, the operators expand, widen or stretch the leathers by means of an initial manual action which, however accurately performed and however proven the skill and experience of the operators involved, is intrinsically empirical and does not take into account the type, shape and condition of the various leathers which, as it is known, vary from batch to batch and sometimes even from leather to leather in the same batch.

Furthermore, the physical condition itself (for example, in terms of health), concentration and/or tiredness of the operators vary throughout a working day and from one working day to another, so that the strength with which they manage to stretch or open the tannery leathers on the support frames obviously varies over time.

Such situation concretely represents a drawback widely felt in the leather industry when considered how, in the prior art, the leathers thus loaded onto the support frames by the operators are further and mechanically widened or stretched by the actuation means which, as mentioned, the drying and/or conditioning plant in question is provided with.

Indeed, as soon as they reach the operating tunnel, the support frames, loaded with the leathers to be dried and/or conditioned, are subjected to the mechanical action of the actuation means which widen the support frames conventionally according to a vertical direction (as known, such support frames consist of mutually telescopic elements) with a consequent extension of the surface of the tannery leathers supported thereby and previously fixed to the support frames by the operators in the loading and unloading station.

It is no coincidence that, in recent years, plants and methods have been developed for drying and/or conditioning leathers or similar flexible laminar surfaces which improve the aforesaid general situation, providing for an automatic and continuous control of the state of tension of the leathers hanging from the various support frames.

Nonetheless, in the type of plants of the leather industry (and those related thereto), which have been summarily and briefly described above, drawbacks are still there of a different nature and of a different profile.

One of the main drawbacks from which the plants of the prior art which are of interest herein still suffer derives from the fact that, when the operators, for any reason, have to leave the leather maneuvering (or loading and unloading) station for a period of time which is more or less prolonged, and in any case not negligible (generally, for more than half an hour), the plant must be stopped and, consequently, the drying and/or conditioning treatment of the leathers which are still inside the operating tunnel must be suspended.

This inevitably and negatively entails a failure to comply with the times of the processing (or treatment) recipe, predetermined, programmed and established as adequate for a given batch of leathers.

In return, in the current state of the art, it often occurs that the leathers belonging to a given production batch and, therefore, somewhat similar to one another in terms of composition and origin, are not treated homogeneously in the operating drying and/or conditioning tunnel, with the consequent production of different material with different qualitative features, even when starting from the same aforesaid batch; however, this is an aspect which contrasts with the requests of the clients and/or with downstream operational needs.

Furthermore, following the operating method implemented today by a drying and/or conditioning plant for leathers comprising an operating drying tunnel, the processing times are often inevitably lengthened, suboptimal and in any case improvable, especially during a lunch break for the operators or the absence thereof from the plant which is not negligible in terms of time duration, for example exceeding a few tens of minutes.

Therefore, starting from the awareness of the above disadvantages of the current state of the art, the present invention intends to remedy it.

In particular, it is main purpose of the present invention to implement a process for drying and/or conditioning tannery leathers, or similar flexible laminar surfaces, which allows to comply with the times of a recipe for processing the same leathers to an extent which is optimal or at least clearly improved with respect to the prior art.

Within the scope of such a purpose, it is the task of the present invention to implement a process for drying and/or conditioning leathers or similar flexible laminar surfaces which allows to satisfy, on one hand and in first instance, the needs of the processing departments downstream of a drying and/or conditioning plant for leathers comprising an operating drying tunnel and, on the other hand and ultimately, those of the customers, in a better way with respect to the current state of the art.

It is another task of the invention to perfect a process for drying and/or conditioning leathers which allows to treat the leathers of a given batch, which are assumed to be somewhat similar to one another in composition, homogeneously or as homogeneously as possible with respect to what occurs in the prior art.

It is a second purpose of the invention to indicate a process for drying and/or conditioning leathers which allows the leathers to be treated effectively in shorter times with respect to what occurs in the prior art, limiting, if not eliminating, processing downtime due to plant shutdown.

It is a last but not least purpose of the present invention to provide a process for drying and/or conditioning leathers or similar flexible laminar surfaces which, substantially, allows to improve, in comparison with the prior art, the performance of a drying and/or conditioning plant comprising an operating drying tunnel (or drier).

Said purposes are achieved by means of a process for drying and/or conditioning leathers or similar flexible laminar surfaces, as in the attached claim 1 , to which reference is made for the sake of brevity.

Further detailed application features of the process of the invention are contained in the related dependent claims.

The aforesaid claims, hereinafter specifically and concretely defined, are intended as an integral part of the present description.

Advantageously, the process for drying and/or conditioning leather or similar flexible laminar surfaces of the invention follows the times of a leather processing recipe to a decidedly better extent with respect to what occurs in equivalent processes of the known type.

This is due to the fact that the process of the invention advantageously comprises, in the order, the following operations: a) downstream the outlet mouth of the operating tunnel, automatically and seamlessly advancing (in other words, without any type of stop) towards the inlet mouth of the operating tunnel at least one main group of said support frames loaded with leathers yet treated, preferably keeping them constantly on a vertical plane while they are transferred from the outlet mouth to the inlet mouth, passing through a leather loading and unloading station which is external to the operating tunnel and accessible to at least one operator; b) automatically continuing the operations of treating the leathers loaded on the support frames and leading the latter out of the operating tunnel, for those load support frames still present inside the operating tunnel due to the operation of automatically re-introducing into the operating tunnel through the inlet mouth, progressively one by one and arranged according to a vertical plane, the support frames belonging to the main group and loaded with yet treated leathers, without such yet treated leathers present in the support frames being again subjected to the drying and/or conditioning treatment inside the operating tunnel.

Equally advantageously, the process for drying and/or conditioning tannery leathers or the like of the invention follows the predetermined processing recipe for a given batch of leathers in a manner more faithful than the processes actuated in the prior art, to full advantage of the treatment uniformity of the leathers themselves.

Equally advantageously, the process for drying and/or conditioning leathers of the present invention allows to shorten the execution times thereof with respect to equivalent processes of the known type, in the presence of situations in which, during the process, the operators in charge of the management thereof are absent from the plant for a prolonged time, for example the time necessary for the lunch break. Advantageously, therefore, the process for drying and/or conditioning leathers of the present invention allows to improve the efficiency of the drying and/or conditioning plant comprising an operating drying tunnel which implements it.

Further features and particularities of the invention will become more evident from the following description, relating to a preferred embodiment of the process for drying and/or conditioning leather for which exclusive rights are claimed herein, given by way of indicative, but not limiting, example, with the aid of the accompanying drawings, in which figures 1 -10 show a possible but not limiting and non-binding operating sequence which is obtainable with, or feasible by, the process of the invention.

As acquired in the prior art (and not shown in the accompanying Figures), the process for drying and/or conditioning leathers comprises, in the order, the following operations: a) stably and temporarily coupling to the side faces 1 a, 1 b of a plurality of support frames 1 (not visible in the following figures) leathers on which to perform a drying and/or conditioning treatment in an operating tunnel 2 of a tannery plant, forming a plurality of load support frames 6; b) arranging the load support frames 6 along a vertical plane and automatically advancing them one after the other towards the operating tunnel 2; c) automatically introducing into the operating tunnel 2, through an inlet mouth 3 made in the operating tunnel 2, progressively one by one, the load support frames 6, always arranged according to the aforesaid vertical plane; d) progressively subjecting the leathers loaded on the support frames 1 to the drying and/or conditioning treatment while the support frames 6 automatically advance in the operating tunnel 2 along a longitudinal direction X, along to a predetermined processing recipe; e) due to the thrust exerted along such longitudinal direction X by each of the load support frames 6 progressively entering said operating tunnel 2, leading out (or, in other words, extracting or expelling) of the operating tunnel 2, through an outlet mouth 4 opposite to the inlet mouth 3, progressively one by one, the support frames 1 loaded with leathers just subjected to the drying and/or conditioning treatment. It should therefore be noted that, in the following, reference numeral 1 indicates the support frames considered alone, as such, while reference numeral 6 indicates the loaded support frames (loaded with leathers, to be treated or yet treated inside the operating tunnel 2).

In accordance with the invention, the process comprises, in the order, the following operations: f) downstream (or just outside) the outlet mouth 4 of the operating tunnel 2, automatically and seamlessly advancing towards the inlet mouth 3 of the operating tunnel 2, in this case, only a main group of support frames 1 loaded with leathers yet treated, passing through a loading and unloading station 5 for the leathers to be treated and yet treated respectively, arranged outside the operating tunnel 2 and accessible to at least one operator (preferably two operators R, as shown in Figures 1 -9); g) automatically continuing the operations referred to in previous points d) and e) for the load support frames 6 still present inside the operating drying tunnel 2 due to the operation of automatically re-introducing into the operating tunnel 2 itself through the inlet mouth 3 thereof, progressively one by one and arranged along a vertical plane, the support frames 1 belonging to the main group and loaded with yet treated leathers, without these yet treated leathers themselves present in the support frames 1 being again subjected to the drying and/or conditioning treatment when they go back inside the operating tunnel 2.

In particular, the operation of leading out of the operating tunnel 2 each of the support frames 1 loaded with leathers yet treated takes place in such a way that (or due to the fact that) entry into said operating tunnel 2 through the inlet mouth 3 of each of the support frames 1 loaded with leathers causes the exit, on the opposite side, from the operating tunnel 2 through the outlet mouth 4 of one of the support frames 1 loaded with the just treated leathers.

Furthermore, in a non-binding but advantageous manner in operational terms, the operation referred to in the previous point f) occurs by constantly keeping the support frames 1 of the aforesaid main group on the vertical plane while they are transferred from the outlet mouth 4 to the inlet mouth 3 outside the operating tunnel 2. Preferably but not exclusively, the operation referred to in previous point f) consists in intervening, by an operator R, on a control panel (not shown in the accompanying Figures) arranged near the operating tunnel 2 and equipped with a central processing and control unit automatically adjusting the movement of the support frames 1 and 6 along a prefixed closed path P and, also, automatically managing the drying and/or conditioning treatment according to the aforesaid predetermined processing recipe stored in the central processing and control unit. Advantageously, according to what is photographed in Figure 10 (or is shown in a static manner), the operations referred to in previous points f) and g) occur in the absence of operators (hence the term "automatically" used therein) at least in the leather loading and unloading station 5, external to the operating tunnel 2 and between the outlet mouth 4 and the inlet mouth 3 of the operating tunnel 2: the loading and unloading station 5 is, in fact, the position from which the operators usually and habitually follow the operation of the plant, loading from time to time the leathers to be treated in the operating tunnel 2 onto the support frames 1 and collecting from time to time the leathers which have just been treated in the operating tunnel 2 from the support frames 1 .

In addition, it should be noted that the operation referred to in previous point f) requires that the support frames 1 of the main group, loaded with yet treated leathers, are seamlessly moved one after the other without being stopped along a front section 7 of a prefixed closed path P which is followed by the support frames 1 during the drying and/or conditioning treatment.

In further detail, such front section 7 extends externally to the operating tunnel 2 and, even more precisely, from the outlet mouth 4 to the inlet mouth 3.

In a preferred but non-binding manner, the operation referred to in the aforesaid point f) provides, in the specific case, for automatically advancing towards the inlet mouth 3 of the operating tunnel 2 only one part - the main group introduced above - of support frames 1 load with leathers yet treated.

However, in other applications of the process of the invention, which are not accompanied by any reference drawing below, the operation referred to in the aforesaid point f) may provide for automatically advancing towards the inlet mouth of the operating tunnel all said support frames loaded with leathers yet treated, up to the completion of the treatment cycle: this means that, in this case, the processing of the entire batch of leathers will occur automatically, in the absence of operators, so that the predetermined processing recipe will be performed automatically for a period of time with a variable duration but generally within the range of 2-?3 hours.

According to the preferred embodiment of the invention described herein, well schematized by the accompanying figures 1 -9, the method further comprises the following operations, performed at least before said operation referred to in previous point g): h) outside the operating tunnel 2 and immediately downstream the outlet mouth 4, overturning by 90° (manually or automatically) only a preliminary group of load support frames 6, arranging them along to a horizontal plane; i) manually removing the leathers yet treated from the preliminary group of support frames 1 just overturned; j) manually counter-overturning by 90° the preliminary group of support frames 1 overturned before without said leathers, arranging them along to a vertical plane; k) automatically advancing towards the inlet mouth 3 of the operating tunnel 2 the preliminary group of support frames 1 counter-overturned and without said leathers; l) automatically re-introducing into the operating tunnel 2 through the aforesaid inlet mouth 3, progressively one by one and arranged along to a vertical plane, the support frames 1 belonging to the preliminary group and depict of said leathers.

As shown in figures 1 -3, the preliminary group of load support frames 6 comprises, in this case, purely by way of explanation, three support frames 6, each of which is first overturned by 90° (for example, clockwise) by the operators R, then stripped of the leathers just treated in the operating tunnel 2 and finally counter-overturned again by 90° (counterclockwise, as a consequence of the direction of the previous overturning) by the operators R and conveyed forward in a vertical position towards the inlet mouth 3 of the operating drying tunnel 2, as illustrated in figures Preferably but not necessarily, the operation referred to in previous point f) is performed after the operation referred to in previous point j) has been completed on each of the support frames 1 of the preliminary group.

This doesn’t absolutely exclude that further embodiments of the process of the invention, not schematized hereinafter by means of figures, may provide that the operation referred to in previous point f) be performed while the operation referred to in previous point j) is still in progress, providing for a suitably slowed advancement of the main group of support frames loaded with leathers just treated for an interval sufficient to allow leathers to be unloaded from the support frames of the preliminary group and their subsequent positioning along a vertical plane.

Furthermore, the process of the invention comprises the operation of automatically stopping the drying and/or conditioning treatment when the leathers of all the load support frames 6 have been treated inside the operating tunnel 2.

In addition, by way of preference, but not of limitation, the process of the invention includes the operation of suspending the automatic operations referred to in previous points f) and g), performed by means of the intervention of an operator R who accesses correctly, using safety accesses, the maneuvering station, for loading and unloading 5 the leathers: this operation occurs when the operators R go back to the workstation thereof, for example at the end of the lunch break, and resume full control of the operation of the plant.

In particular, the operation of suspending the automatic operations referred to in previous points f) and g) is performed by the operator acting on the control panel located near the operating tunnel 2 and equipped with the central processing and control unit cited above, which automatically adjusts the movement of the support frames 1 and 6 along the prefixed closed path P.

Advantageously, although not exclusively, the process of the invention comprises the operation of constantly detecting, by means of suitable sensors, the arrangement of each of the support frames 1 and 6, performed upstream of the inlet mouth 3 of the operating tunnel 2 and downstream of the loading and unloading station 5 before the operation referred to in previous point b) and before the operation referred to in previous point f), as well as after the operation referred to in previous point c). Equally advantageously, but not necessarily, the process of the present invention also comprises the operation of constantly detecting, still using suitable sensors (for example, platforms with sensors), the presence of operators R and/or people at a danger zone 8 defined at the front section 7 of the prefixed closed path P along which the support frames 1 and 6 are moved outside the operating tunnel 2. Preferably, the method of the invention also comprises the operation of stopping the automatic operations referred to in previous points f) and g) if the arrangement of each of the support frames 1 and 6 upstream of the inlet mouth 3 of the operating tunnel 2 and downstream of the loading and unloading station 5 is incorrect and defines a non-vertical plane or if the operators R and/or people are present in the danger zone 8.

As already highlighted several times, figures 1 -10 show the sequence of a part of the preferred embodiment of the process for drying and/or conditioning leathers object of the invention, in which, in particular, figure 10 expresses the characterizing part of the accompanying claim 1 , i.e., the continuous execution of the process, in the absence of the operators R and with the loaded support frames 6 which, outside the operating tunnel 2 (and in the front section 7 of the prefixed closed path P which starts from the outlet mouth 4 and ends at the inlet mouth 3 thereof) are not overturned by 90° and, also in such front section 7, therefore advance while always remaining arranged along to a vertical plane.

In addition, in this case, in a purely preferred and non-binding manner, the operators R unload the leathers from the three support frames 1 of the preliminary group without recoupling others on the respective side faces 1 a, 1 b thereof.

On the basis of the description just provided, it is therefore understood that the process for drying and/or conditioning tannery leathers (or similar flexible laminar surfaces) of the present invention achieves the purposes and provides the advantages mentioned above.

Upon implementation, changes could be made to the process for drying and/or conditioning tannery leathers (or similar flexible laminar surfaces) of the invention, consisting, for example, in coupling (generally, by nailing) leathers only to one of the two side faces of one or more of the support frames to be introduced into the operating tunnel. Finally, it is clear that numerous other variations could be made to the process for drying and/or conditioning the tannery leathers in question, falling within the scope circumscribed by the attached claims.

Where the constructional features and techniques mentioned in the following claims are followed by reference signs or numerals, such reference signs were introduced for the sole purpose of increasing the intelligibility of the claims themselves, and therefore have no limiting effect on the interpretation of each element identified, by way of example only, by such reference signs.