Reversible coating machine for roller finishing of leather or like

Abstract

The present invention relates to the field of finishing processes for coating leathers and similar sheets. More accurately, the present invention relates to a dedicated coating machine for roller finishing of leather, which coating machine is configured to be operated reversely, i.e. With so-called "synchronization" and so-called "reverse" operation. Specifically, the machine is equipped with a motorized blade that acts as a blade (in reverse mode), as well as a leather separating device when the machine is operating in synchronous mode.

Description

Technical Field

[0001] The present invention relates to the field of finishing processes for coating leather and similar sheet materials. More precisely, the present invention relates to a special coating machine for roller finishing of leather, which is configured to be reversibly operable, i.e., with so-called "synchronous" operation and so-called "reverse" operation. Background Art

[0002] Conventional roller coating machines for coating leather with liquid finishing chemicals which impart the desired final surface properties to the leather are well known in the art. They are configured to operate only in synchronized mode, i.e. the engraved roller rotates in the feed direction of the underlying leather feed system, or only in reverse mode, i.e. the engraved roller rotates in the direction opposite to the aforementioned feed direction.

[0003] In both types of machines, there are doctor blades acting as scraper blades for the coated material, arranged to rest at different positions on the roll (in the first case, on the inlet side of the material, in the second, on the opposite side) depending on whether the machine is synchronous or reverse. When processing natural leather, i.e. loose sheets rather than rolled material, synchronous machines also require a separation system on the side opposite to the inlet side, i.e. the outlet side, to counteract the natural tendency of the leather to adhere to the cellular surface of the embossing roll. Such a system can be automatic in nature, and various solutions have been proposed in this regard (e.g. counter-rotating closed-loop sleeves, toothed rolls of various shapes and sizes), but, referring to machines that are only synchronous, manual intervention is usually still also simply used.

[0004] Recently, however, reversible machines have been developed, i.e. machines capable of operating in both reverse and synchronous modes. These machines therefore have two scrapers in opposite positions, which perform their functions depending on whether the machine is operating in one mode or the other. In these machines, however, the presence of the reverse mode scraper in the leather exit area creates complications with respect to the hide removal function in synchronous operating mode. In fact, the basic construction of these machines, always designed in its original configuration to achieve high efficiency in reverse mode, has limitations in terms of the possibilities and / or space for accommodating the support and control system of the series of toothed rollers used for the hide separation function for a wide range of articles. The location of the separation system is usually close to the location occupied by the reverse mode scraper and the entire separation system must be removable and repositionable, since the simultaneous presence of the separation system is incompatible with the operation of the machine when it is operating in reverse mode.

[0005] On the other hand, when the machine is operating in synchronous mode, the reverse scraper is not used and, in order to prevent it from generating unnecessary or problematic bulk, it is removed, so that when switching from synchronous mode to reverse mode, the machine must be stopped, the leather separation device removed and then the reverse scraper installed. Since the machine, which also operates in reverse, is equipped with a conveyor belt, this makes it more difficult to access the machine space to carry out the change, which, in addition to being time-consuming, also makes the subsequent operation very difficult.

[0006] It can therefore be generally said that the amount of manipulation and adjustments to be carried out when there is a need to change articles and / or to switch from reverse to synchronous or vice versa inevitably requires a loss of time that can be estimated at 30-45 minutes. The main complication of this type of machine is ultimately related to the need for motorized auxiliary devices for separating the hides, and this significantly increases the complexity of the machine, taking into account the need to comply with all the increasingly stringent requirements introduced by recent safety regulations.

[0007] Returning specifically to the blade, as is known, a particular blade in its operating position is placed in contact with an embossing roller, usually made of chrome-plated steel, thus forming a kind of basin containing the chemical used for the coating. The latter leaves a groove formed at a point of proximity between the blade and the embossing roller. The amount of product dispensed depends strictly on the size of this groove, which in turn is determined by the pressure with which the blade insists on the surface of the embossing roller. When the system is ideally adjusted, the amount of product that passes is exactly the same as that capable of filling the engraving of the embossing roller, which has been precisely produced for the purpose of fixing the amount of product that must reach the leather to be treated.

[0008] Too high a roller pressure will prevent the roller from sliding properly, while a pressure lower than the optimum value will result in a film of liquid product flowing through, which will spread over the leather, creating defects, in addition to the desired product already present in the engraving. Current commercial machines use a blade driven by an air piston, which controls its open / closed state relative to the contact position with the roller, after which the operator can adjust the pressure that the blade must apply to the embossing roller by a manually operated thumb wheel associated with a worm screw. This pressure varies from process to process, depending on the viscosity of the chemical product to be applied, the linear speed of the conveyor belt and the rotation of the embossing roller.

[0009] Since precise control of the pressure of the blade against the embossing roller is a decisive aspect for controlling the amount of treatment liquid to be dispensed, and therefore for the success of the process, the same Applicant has proposed a motorized blade with a digital control that allows the operator to select and apply the desired pressure on the embossing roller in a very strict manner, and also allows the same operation to be repeated over time. This makes it possible to optimize the way in which the blade is used in the blade pressing function to define the amount of chemical product dispensed onto the leather through the embossing roller. Summary of the invention

[0010] In view of the above-mentioned technical status, the applicant has now proposed an unexpectedly effective solution, providing a synchronous-reverse coating machine and its operating method, which overcomes the problems of the known machines by improving the construction, in particular the problems mentioned above of large size, complex structure and long downtimes limiting productivity due to the need for additional separation devices when operating in synchronous mode.

[0011] According to the invention, the synchronous-reverse coating machine for roller finishing of leather and the like, which achieves the above-mentioned results, has the essential features listed in the first claim of the appended claims. Still according to the invention, the operating method implemented in the context of such a machine has essentially the features of the appended claim 8. Other additional features are the subject of the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The features and advantages of the synchronous-reverse coating machine and method for roller finishing of leather or the like according to the invention will become more apparent from the following description of one of the embodiments of the invention, provided by way of example and not limitation, with reference to the accompanying drawings, in which:

[0013] Figure 1 and Figure 2 A schematic side view of a machine according to the invention is shown in two consecutive operating steps in synchronous mode. DETAILED DESCRIPTION

[0014] With reference to the aforementioned figures, the present invention is primarily based on the intuition that, by suitably constructing a reversible roller coating machine with a reverse mode blade equipped with an independently motorized device, such a machine can also be effectively operated in a synchronous mode, without the need to install an auxiliary separation roller (or equivalent) and without the need for any disassembly operations when switching from one operating mode to another. To this end, by suitably constructing the control system of the machine, it has surprisingly been found that simply moving the reverse blade into a position of interference with the hide being processed on the roller when the reverse blade approaches the roller can promote the separation of the hide and ensure that the hide is deposited on the underlying outlet conveyor system.

[0015] In more detail, the drawing shows a schematic side view of the main functional elements of the machine; it is obvious that a more analytical description of these elements is not necessary, since the design details of these elements are themselves well known to a person skilled in the art.

[0016] The machine thus comprises: at least one cylindrical embossing roller 1, rotating about its central axis X, and a feeder 2 for leather material, for example with a conveyor pad, directed towards the roller 1 in a plane A substantially tangential to the roller, according to a linear feed direction Y and a feed direction evident towards the roller. The feeder 2 is located on the inlet side of the roller itself. A counterroller 3 is usually placed below the embossing roller 1 and defines, together with the embossing roller 1, the inlet area for the leather material fed by the feeder.

[0017] On the inlet side, a first scraper 4 is also arranged, which, as is known, cooperates in contact with the side surface of the roller along the generatrix of the roller for spreading the liquid on the leather material. This first scraper 4 is a scraper intended for the material distribution function in synchronous operating mode, that is, when the roller rotates about the X axis at the entry point of the leather material in a direction consistent with the feeding direction Y.

[0018] A second blade 5 for distributing the spread material is arranged at right angles on the outlet side of the roller, which is opposite to the inlet side and on which a conventional system 6 for conveying the coated leather leaving the roller 1 extends. The second blade 5 is then designed to cooperate with the side surface of the roller 1 along the generatrix of the roller 1. This second blade is a so-called reverse mode blade, which means that the blade is designed to perform distribution work when the roller rotates in a direction opposite to the feed direction of the introduced leather. Both blades have known structures, which are neither described nor shown in detail. However, the second blade 5 or the reverse mode blade is obviously equipped with its own independent motor device, which allows position control at least when approaching and moving away from the roller.

[0019] In addition to these motorized means of the second scraper 5 or the reverse scraper, the machine's drive means obviously include motorized means for rotating the drive roller 1, not shown, all of which are subordinate to a control device (an electronic control unit according to the technology commonly used in the field) that is configured to control the machine in a synchronous operating mode, in which the first scraper 4 is enabled for its function of spreading the material, and in a reverse operating mode, in which the second scraper 5 is enabled to perform its traditional function of spreading the material.

[0020] If the reverse operation is carried out in a conventional manner, the particularity of the machine according to the invention is associated with the synchronous operating mode, a precise representation of which is provided in the figure. In fact, despite the lack of auxiliary devices / equipment for separating the hides, such as conventional rollers, which is characteristic of this machine and can also be extended to any assembly arrangement, the separation of the hides on the outlet side is ensured by the fact that the control device activates the reverse scraper 5 through its independent motorization, bringing the latter, or more precisely the blade concerned, closer to the embossing roller 1, until a position of interference with the hides leaving the roller itself, in order to counteract the adhesion phenomenon and make the hides fall onto the output conveyor system 6. It is therefore precisely the movement of the reverse motorized scraper 5 that is effectively utilized in an unexpected way, not only in its conventional dispensing function, to adjust the position of the scraper, but also in the synchronous mode. In the latter case, the scraper is no longer an unnecessary burden or even a component to be removed, but assumes the essential role of a disassembly device, avoiding the need for the assembly of auxiliary components, thus keeping the machine configuration unchanged, with all the advantages that come with it.

[0021] therefore, Figure 1 A piece of leather T is shown being treated by an embossing roller 1, wherein the synchronous scraper 4 operates to fulfill its function of distributing the material to be coated onto the roller, and the leading edge of the leather is about to reach the area of ​​the counter scraper 5 on the outlet side. There, the interference with the blade edge ( Figure 2 ) causes a piece of the head to separate, followed by the rest of the body of the leather piece / hide until it falls onto the conveyor system 6.

[0022] In practice, the control system provides different settings or setting programs for the position and therefore the pressure of the reverse blades / scrapers, each of which can be selected or preferably automatically set according to a specific synchronous or reverse operating mode and therefore according to a different function / purpose (liquid distribution in reverse mode, leather separation in synchronous mode).

[0023] The leather separation function can be arranged such that in the interference position, the end edge of the blade / scraper is at a distance of 0.1 mm to 0.5 mm from the side surface of the roller. In the case of this arrangement or according to this arrangement, the blade travel between the interference position and the rest position is between 50 mm and 80 mm.

[0024] Optionally, the machine control system may include a sensor device for detecting the position of the leather material on the embossing roller 1, and the machine control system is configured to start the second scraper or counter scraper 5 based on the position signal obtained from the position sensor and appropriately time it to optimally perform the separation function without interfering with the coating operation.

[0025] Thus, according to the invention, a surprisingly effective method (expedient) is provided, which makes it possible to optimize existing components without introducing new ones and enables the machine to carry out practically all processing operations (synchronous / reverse), thus making the machine very quickly and safely universal. 5. As mentioned above, the machine can always work without needle rollers or equivalent auxiliary devices specifically for separating the skins leaving the embossing rollers, but its infrastructure can also be generally without accessories for assembling such needle rollers or equivalent auxiliary devices.

[0026] So far, the invention has been described with reference to preferred embodiments thereof. It is intended that there may be other embodiments directed to the same inventive core, all of which fall within the scope of protection of the claims presented below.

Claims

1. A coating machine for finishing leather or similar sheet materials, the coating machine comprising: At least one cylindrical embossing roller (1); A feeding device (2), the feeding device (2) being used for feeding leather material on a plane substantially tangent to the embossing roller (1) according to a linear advancing direction (Y) and orientation, the feeding device being arranged on an inlet side of the roller; At least one first scraper (4), the at least one first scraper (4) being used to distribute the coating material arranged on the inlet side of the roller and facilitating cooperative contact with the side surface of the embossing roller (1) along the generatrix of the embossing roller (1); at least one second scraper (5), the at least one second scraper (5) being used to distribute the coating material arranged on the outlet side of the embossing roller (1) so as to facilitate the mating contact with the side surface of the roller along the generatrix of the roller, the outlet side being radially opposite to the inlet side; an actuating device and a control device, the actuating device and the control device being configured to drive the machine according to a synchronous operating mode and a reverse operating mode, in which the embossing roller (1) rotates in a direction consistent with the direction of the linear advancement and the at least one first scraper (4) is activated for the function of material dispensing, and in which the embossing roller (1) rotates in a direction opposite to the direction of the linear advancement and the at least one second scraper (5) is activated for the function of material dispensing, wherein the actuating device comprises an independent motorized device associated with the at least one second scraper (5) for controlling the position of the at least one second scraper (5) at least in movement towards and away from the embossing roller (1), and The control device is configured to start the at least one second scraper (5) through the independent motorized device in the synchronous operation mode to move the at least one second scraper (5) to a position where the scraper interferes with the leather material leaving the embossing roller (1), thereby promoting the separation of the leather material from the roller.

2. The machine according to claim 1, wherein: The control device comprises a position sensor device for the leather material on the embossing roller (1), and the control device is configured to activate the at least one second scraper (5) according to a leather material position signal obtained from the position sensor device.

3. A machine according to claim 1 or 2, wherein: The interference position between the at least one second scraper blade (5) and the leather material is established so that the distance between the end edge of the scraper blade (5) and the side surface of the embossing roller (1) is between 0.1 mm and 0.5 mm.

4. The machine according to claim 3, wherein: The at least one second scraper (5) is movable between the interference position and a rest position, wherein the interference position and the rest position are linearly separated by a stroke of between 50 mm and 80 mm.

5. Machine according to any of the preceding claims, without a hide separating roller or equivalent auxiliary hide separating means designed only for separating hides leaving the embossing roller.

6. Machine according to any of the preceding claims, without mounting means arranged to mount a hide separating roller or equivalent auxiliary hide separating means designed only for separating hides leaving the embossing roller.

7. A machine according to any one of the preceding claims, wherein: The control device is configured to manually or automatically select two different programs for setting the position of the second scraper (5), one program being associated with the material dispensing function in the reverse operating mode and the other program being associated with the leather separation function in the synchronous operating mode.

8. A method for controlling a machine according to any one of the preceding claims, wherein: In the synchronous operation mode, the at least one second scraper (5) is activated by the independent motorized device to reach a position where it interferes with the leather material leaving the embossing roller (1) to promote the separation of the leather material from the embossing roller (1).

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