Industrial plant for milling tannery leathers

Abstract

An industrial plant (1) for milling tannery leathers comprising a milling drum (2) comprising a hollow body (3), suitable to be rotated around an axis of symmetry (X) through motorization means and inside which the leathers to be treated are received, a closed recirculation circuit (4), operatively connected to the hollow body (3) of the milling drum (2) for the introduction into, and exit from, the hollow body (3) of air (A) for the treatment of the leathers, a dust collector (5) for cleaning the air (A), arranged outside the hollow body (3) of the milling drum (2) and downstream the hollow body (3) following the path of the air (A) in the closed recirculation circuit (4), as a reference direction, forced ventilation means (6), for example, arranged downstream the dust collector (5) following the path of the air (A) inside the closed circuit (4), as a reference direction. In particular, the industrial plant (1) comprises at least one low energy consumption heating element (8), suitable to produce heat which intercepts the air (A) to heat it, and arranged in the closed recirculation circuit (4) outside the hollow body (3).

Description

[0001] INDUSTRIAL PLANT FOR MILLING TANNERY LEATHERS

[0002] The present invention relates to an improved industrial plant for milling tannery leathers, or similar flexible and special laminar surfaces (such as imitation leather, ennobled leather, hide, and so on).

[0003] Firstly, it is worth noting that in the tanning industry, the term "milling" refers to the treatment of leathers in a fluid-tight machine known as a "drum”. The treatment is performed to prepare the leathers for finishing and to impart aesthetic appearance and suppleness thereto during the finishing steps.

[0004] Typically, the parameters of a milling cycle recipe comprise:

[0005] • rotation speed;

[0006] • rotation duration;

[0007] • rotation reversal time (it spins in one direction and then in the opposite direction);

[0008] • air temperature inside the drum and input air temperature;

[0009] • relative humidity of the air inside the drum.

[0010] Typically, the air temperature and the relative humidity can have curves during the process step according to the processing and type of material.

[0011] However, these parameters are the main parameters of a milling cycle, which also comprise other parameters, e.g., such as chemical products introduced into the drum, quantity and type of leathers treated in the drum, quality of air introduced into the drum, and so on.

[0012] More in detail, milling is a process of the mechanical type which is carried out on any type of special fabric - generally, animal skins - to accentuate a surface embossing (called “grain” in the technical jargon) or to give the product the appearance of aging or wrinkling, make it supple or to eliminate possible creases and thus prepare it for the next processing steps.

[0013] Indeed, the material is subjected to a mechanical action by effect of the rolling thereof inside the hollow cylindrical basket or barrel (which may be perforated), which constitutes the main part of the machine (or drum) and which operates by rotating about a transversal, generally horizontal, axis. In general, in the prior art, an industrial plant comprises a milling drum, which in turn comprises a substantially hollow cylindrical body, suitable to be rotated about an axis of symmetry by means of motorization means and inside which the leathers to be treated are received.

[0014] An industrial leather milling plant of the prior art further comprises a closed circuit for recycling the internal air (in the form of one or more pipes), operationally connected to the rotating hollow cylindrical body (drum).

[0015] Furthermore, a typical industrial leather milling plant of known type may comprise a dust collector for cleaning the air mounted outside the milling drum, it intercepts the air which is recycled in the pipes and filters it.

[0016] It is normally placed immediately downstream the outlet of the internal air.

[0017] The dust collector provides an air filtration system and, generally, it is of the filtering sleeve (or bag) type supported by a supporting structure enclosed by an outer casing and has forced ventilation means suited to force air through the filtering systems.

[0018] Notoriously, the filter bags are used for dry and liquid industrial dust collection, by means of the separation of dust or impurities (above all fibers of the leathers being processed in the drum) in suspension in the air, by virtue of the materials with which they are made and which range, for example, from polyester to polypropylene, cotton, wool-nylon compound or technical fabrics.

[0019] Substantially, the impurities (dust) in the air that enters into the filtering sleeves of the dust collector progressively stick to the inner wall of the sleeves themselves and from here they decant by gravity downwards to accumulate in a removable collection box located in the lower part of the dust collector and accessible by the operator.

[0020] Finally, generally but not necessarily, a traditional industrial leather milling plant of the prior art may include an exchange valve arranged on the air pipe inside the closed circuit, and a group of electrical resistors, following the air path in the closed circuit as a reference direction.

[0021] It is well known and recognized that the group of electrical resistors, as the heating element of the air which is introduced into the milling drum in order to treat the leathers, is unduly and disadvantageously a rather significant source of energy consumption, which, at present, no operator in the industry has yet thought to reduce.

[0022] Examples of milling plants of known type for the present discussion are shown in prior patent documents EP3601622 B1 and WO2022 / 029569 A1 (owned by the applicant and obviously known thereby), while prior patent document CH680224 A5 shows a leather or hide drying machine and, thus, doesn’t refer to a milling plant and the heat pump performs the function of dehumidifier and not of heat generator.

[0023] Therefore, starting from the awareness of the aforesaid drawbacks suffered by the prior art considered hereto, the present invention aims to effectively overcome such drawbacks.

[0024] In particular, it is main purpose of the present invention to provide an industrial plant for milling leathers which entails lower power consumption than the equivalent industrial plants of known type, without affecting the effectiveness of the leather treatment.

[0025] In other words, it is primary purpose of the invention to make available an industrial leather milling plant that reduces the required supply of electricity compared to the prior art while maintaining a leather treatment efficiency level at least equal to that of similar industrial plants of the known type.

[0026] Therefore, in the cognitive sphere of such a main purpose, it is task of the present invention to devise an industrial leather milling plant which, compared to similar plants of known type, entails a lower production cost, the other factors involved in this cost calculation, such as the cost for raw materials and labor employed, being equal.

[0027] Another task of the invention is to devise an industrial plant for milling tannery leathers which is a relevant improvement from an environmental impact point of view compared to the prior art, in relation to energy consumption.

[0028] It is a second purpose of the invention to indicate an industrial plant for milling tannery leathers which makes it possible to maintain the integrity of the heating means for the leather treatment air inside the hollow body of the milling drum for longer than the known industrial plants comparable thereto. It is a last but not least purpose of the present invention to give substance to an industrial plant for milling tannery leathers which has a simple constructive concept, despite the considerable relevance of the objectives it sets with respect to the drawbacks of the prior art, which, at present, no operator has sought to solve or succeeded in remedying (also as a result of consolidated operating habits that certify lack of innovative aptitude and unwillingness to change but which, precisely, contribute to creating the aforementioned drawbacks).

[0029] Said objects are achieved by means of an industrial plant for milling tannery leathers as illustrated in appended claim 1 , to which reference is made for the sake of brevity.

[0030] Further technical features of detail of the industrial plant for milling tannery leathers of the present invention are contained in the corresponding dependent claims.

[0031] The aforesaid claims, specifically and concretely defined below, are intended as an integral part of the present description.

[0032] Advantageously, the industrial plant for milling tannery leathers of the present invention makes it possible to obtain an effective leather milling treatment through a lower contribution of electricity than the industrial plants of the prior art comparable thereto.

[0033] This, by virtue of the fact that the industrial plant for milling tannery leathers of the invention advantageously comprises a heating element which:

[0034] • has low energy consumption and, consequently, low environmental impact, compared with traditional electrical resistors;

[0035] • typically, and preferably, comprises a heat pump;

[0036] • is suitable for producing heat which intercepts the air passing through the closed recycling circuit, external to the hollow body of the milling drum, to heat it;

[0037] • is arranged in the closed air recirculation circuit, outside the hollow body of the milling drum.

[0038] It is worth noting that the term "low energy heating element", as envisioned in the industrial plant of the invention, means a component other than an electrical thermal energy generating system - typically, such as one or more electrical resistors, which have always been used, for consolidated practice, in the leather tanning sector, in plants similar to the one of the present invention.

[0039] Despite recognizing that the efficiency which results from the transformation of electrical energy into thermal energy is quite high, the distinctly more efficient solution adopted in an innovative and novel manner by the industrial plant of the invention is a low energy consumption system, such as, typically, and preferably, a heat pump that generally requires from 25% to 30% of electricity to generate 100% of thermal energy. Indeed, the heat pump draws the remaining part of the energy from the environment (thermal energy from air, subsoil, or water).

[0040] The industrial plant of the present invention produces an unexpected technical effect in the field under examination (leather tanning), and this, as known, is to be regarded as an indication of the presence of novelty but also of inventive step in the exclusively claimed object: this surprising technical effect derives precisely from the object as claimed and is based on the salient, essential and indispensable technical features of the invention, in combination with the known general features.

[0041] In the present invention, appropriately, this technical effect is not based on technical features which are already comprised, in combination, in the prior art, because the use of at least one low energy heating element, preferably a heat pump, in the closed recirculation circuit and outside the rotating hollow body of the milling drum is, at present, unknown and has never been adopted to date in the concerned field.

[0042] Still advantageously, the specific heating means provided by the industrial plant of the invention (as mentioned, one or more low energy heating elements) withstand the aggressiveness of the air (which nevertheless remains, although the air transits and is treated in the dust collector before reaching the heating element) exiting the milling drum, maintaining its functional integrity for an extended period of time.

[0043] Equally advantageously, the technical and innovative concept underlying the present invention can also be extended to existing and / or already operating industrial plants for milling tannery leathers by replacing the typical electrical resistors with the low energy, environmentally-friendly heating elements, such as typically one or more heat pumps, installed in the closed air recirculation circuit outside the hollow cylindrical body of the milling drum, upstream its inlet.

[0044] Furthermore, equally advantageously, the industrial plant for milling tannery leathers of the invention allows a reduction in production costs, because of the specific heating means it uses.

[0045] The objects and advantages mentioned will be more apparent from the description that follows, related to a preferred embodiment of the industrial plant for milling tannery leathers of the present invention, given by way of indicative and nonlimiting example, with the help of the accompanying drawings, in which:

[0046] - figures 1 and 2 are two distinct assonometric views of the industrial plant for milling tannery leathers of the invention;

[0047] - figure 3 is a side view of the industrial plant in figures 1 and 2;

[0048] - figure 4 is a constructive-functional diagrammatic view of the industrial plant in figure 1-3.

[0049] A possible embodiment of the industrial plant for milling tannery leathers of the invention is shown in figures 1 -3 and diagrammatically shown in figure 4, where it is indicated by reference numeral 1 as a whole.

[0050] It is worth noting that an industrial plant 1 for milling tannery leathers comprises:

[0051] - a milling drum 2 comprising a hollow body (or drum) 3, usually cylindrical, supported by a supporting frame 9 and suitable to be set in rotation about an axis of symmetry X through motorization means (not shown for the sake of simplicity of presentation and coupled to the hollow body 3 at the axis of symmetry X thereof) and in which the leathers to be treated are received;

[0052] - a closed recirculation circuit 4, operatively connected with the hollow body 3 of the milling drum 2 for the introduction into, and exit from, the hollow body 3 of air A for the treatment of the leathers;

[0053] - a dust collector 5 for cleaning the air A, arranged in the closed circuit 4 outside the hollow body 3 of the milling drum 2 and downstream the hollow body 3 following the path of the air A in the closed recirculation circuit 4, as a reference direction;

[0054] - forced ventilation means, indicated by reference numeral 6 as a whole, arranged in the closed circuit 4 outside the hollow body 3 and, as a preferred example only, downstream the dust collector 5, again following the path of air A in the closed recirculation circuit 4, as the reference direction;

[0055] - a purely optional exchange valve 7 arranged in the closed circuit 4 outside the hollow body 3 and, again in an illustrative but not limiting manner, downstream the forced ventilation means 6, again following the path of air A in the closed recirculation circuit 4, as the reference direction.

[0056] According to the invention, the industrial plant 1 comprises a low energy consumption heating element 8, suitable to produce heat which intercepts the air A to heat it and arranged in said closed recirculation circuit 4 outside said hollow body 3 of said milling drum 2.

[0057] The low energy heating element 8 (which is preferably arranged downstream both the dust collector 5 and an exchange valve 7, e.g. a three-way valve, and, thus, receives the air A from the exchange valve 7 itself and conveys it into the hollow body 3 of the milling drum 2) comprises, preferably but not necessarily, a gas expansion thermal battery.

[0058] According to the preferred embodiment of the invention described herein, the low energy heating element 8 comprises at least one heat pump 10.

[0059] In this regard, it is worth noting that the prior art document published under CH680224 A5 refers to a machine for drying hide and leathers in general; therefore, the subject matter described therein is largely different from the subject matter of the invention described here.

[0060] Furthermore, prior document CH680224 A5 actually describes a heat pump (divided into an expansion section, indicated by reference numeral 29, and a condensation section indicated by reference numeral 30), which, however, is only used to reduce the relative humidity of air (so that the heat pump is a dehumidifier).

[0061] Indeed, in CH680224 A5, the air passes through the gas expansion battery 29 cooling down, condensing the contained water, and then passes into the gas condensation battery 30, heating up until it returns to its initial temperature.

[0062] It follows that the person skilled in the art, having the documents of prior art mentioned above at hand, could in no way infer the application of a heat pump, of the type indicated by reference numeral 10 here, as a specific heating element applied in the closed recirculation circuit 4 outside the hollow body 3 of the milling drum 2, upstream an inlet 11 of the hollow body 3 itself.

[0063] In particular, the heat pump 10 effectively produces heat at a temperature of at least 40°C. In the invention, already at these temperatures, the treatment of leathers in the hollow body 3 of the milling drum 2 is still effective.

[0064] Still following, as the reference direction, the path of the air A (visible in figure 4) in the closed recirculation circuit 4, the low energy heating element 8 is arranged upstream the inlet 11 obtained in the hollow body 3 of the milling drum 2 with which it communicates by means of a return pipe 12 and to which it conveys the air A just processed thereby.

[0065] The dust collector 5, on the other hand, is conventionally arranged downstream an outlet 13 of the air A obtained in the hollow body 3 of the milling drum 2, communicating with the dust collector 5 itself by means of a delivery pipe 14.

[0066] The outlet 13 is opposed to the inlet 11 , with which it is aligned along the axis of rotation X of the hollow body 2 of the milling drum 3, as also shown in figure 4.

[0067] Thus, it is apparent that the motor means, the dust collector 5 for cleaning the air A, the forced ventilation means 6, the exchange valve 7 and the heating element 8 are arranged in the closed recirculation circuit 4, as previously highlighted outside said hollow body 3 of the milling drum 2.

[0068] In a preferred but not binding manner, the forced ventilation means 6, the possible and optional exchange valve 7, and the low energy heating element 8 are arranged in the order just listed downstream the dust collector 5, following the path of air A (shown in figure 4) inside the closed recirculation circuit 4 as a reference direction, in such a way that the low-energy heating element 8 is the last component crossed by the air A before it is reintroduced inside the hollow body 3 of the milling drum 2.

[0069] Advantageously, the industrial plant 1 of the invention comprises a central processing and control unit arranged in a control panel, not shown in the accompanying figures for the sake of simplicity of exposition, at the disposal of an operator, electrically connected to the motor means, dust collector 5, forced ventilation means 6, exchange valve 7 and low energy heating element 8, to manage the operation thereof. Based on the aforesaid description, it is thus apparent that the industrial plant for milling tannery leathers of the present invention achieves the aims and offers the previously mentioned advantages.

[0070] During the step of implementation, modifications may be made to the industrial plant for milling tannery leathers of the invention, e.g., a different number of low energy consumption air heating elements, as well as a different number of exchange valves, with respect to those described and illustrated in the accompanying figures, with both of these numbers able to vary depending on the design and constructive choices, starting from one.

[0071] Furthermore, there may be other embodiments of the industrial plant for milling tannery leathers, which is exclusively claimed hereafter, not yet depicted below, in which the forced ventilation means may be of a type different from the one described above, without affecting the advantage provided by the present invention.

[0072] Finally, it is apparent that many other variants may be made to the industrial plant for milling tannery leathers described herein, falling within the scope of the appended claims, just as it is apparent that in the practical implementation of the invention, the materials, shapes, and sizes of the details shown may be any, according to the requirements, and may be replaced by other technically equivalent elements.

[0073] Where the constructive features and techniques mentioned in any successive claims are followed by references signs or numerals, such reference signs were introduced for the sole purpose of increasing the intelligibility of the claims themselves, and consequently, such reference signs have no limiting effect on the interpretation of each element identified, by way of example only, by such reference signs.

Claims

CLAIMS1. Industrial plant (1 ) for milling tannery leathers comprising:- a milling drum (2) comprising a hollow body (3), suitable to be rotated around an axis of symmetry (X) through motorization means and inside which the leathers to be treated are received;- a closed recirculation circuit (4), operatively connected with said hollow body (3) of said milling drum (2) for the introduction into, and exit from, said hollow body (3) of air (A) for the treatment of said leathers;- a dust collector (5) for cleaning said air (A), arranged in said closed recirculation circuit (4) outside said hollow body (3) of said milling drum (2) and downstream said hollow body (3) following, as a reference direction, the path of said air (A) within said closed recirculation circuit (4);- forced ventilation means (6), arranged in said closed recirculation circuit (4) outside said hollow body (3) of said milling drum (2), characterized in that it comprises at least one low energy consumption heating element (8), suitable to produce heat intercepting said air to heat it and arranged in said closed recirculation circuit (4) outside said hollow body (3) of said milling drum (2).

2. Plant (1 ) according to claim 1 ), characterized in that said heating element (8) comprises a gas expansion thermal battery.

3. Plant (1) according to claim 1 ) or 2), characterized in that said low energy consumption heating element (8) includes at least one heat pump (10).

4. Plant (1 ) according to claim 3), characterized in that said heat pump (10) produces heat of at least 40°C.

5. Plant (1) according to any of the previous claims, characterized in that said low energy consumption heating element (8) is arranged downstream said dust collector (5).

6. Plant (1 ) according to any of the previous claims, characterized in that following, as a reference direction, the path of said air (A) inside said closed recirculation circuit (4), said low heating element energy consumption (8) is arranged upstream an inlet (11 ) made in said hollow body (3) of said milling drum (2) and communicating through a return pipe (12) with said low energy consumptionheating element (8) from which it receives said air (A) freshly processed by said low energy consumption heating element (8).

7. Plant (1 ) according to any of the previous claims, characterized in that said dust collector (5) is arranged downstream an outlet (13) of said air (A) made in said hollow body (3) of said milling drum (2) and communicating with said dust collector (5) through a delivery pipe (14).

8. Plant (1) according to any of the previous claims, characterized in that said motorization means, said dust collector (5), said forced ventilation means (6) and said heating element (8) are arranged in said closed recirculation circuit (4) at the outside of said hollow body (3) of said milling drum (2).

9. Plant (1 ) according to any of the previous claims, characterized in that it comprises an exchange valve (7) arranged in said closed recirculation circuit (4) outside said hollow body (3) of said milling drum (2).

10. Plant (1) according to any of the previous claims, characterized in that it comprises a central processing and control unit arranged in a control panel available to an operator, electrically connected to said motorization means, said dust collector (5), said forced ventilation means (6) and said heating element (8) to manage operation thereof.

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