MACHINE FOR THE CONTINUOUS APPLICATION OF PROTECTION PRODUCTS ON A METALLIC STRIP

Description

[0001] The present invention relates to machines for the continuous application of protection products on a metallic strip, also called "chem coater".

[0002] Chem coaters are special machines for the continuous deposition of varnishes and/or other finishing products, almost exclusively used in metallic strip process lines in the steel industry.

[0003] Since their very first appearance on the market, these machines have been favoured by specialized steelwork manufacturers due to their qualities of simplicity and performance reliability which are enhanced when a particularly thin deposit is required.

[0004] The concept at the basis of this type of machine is relatively simple: two opposite metallic rolls, with or without a rubber coating, transfer and homogeneously spread the coating material onto one or both of the surfaces of the continuous advancing metallic strip.

[0005] The two rolls are called calibrating and application rolls in relation to their function.

[0006] As in almost all relatively simple machines, the problem encountered relates to regulation. These rolls must in fact have such contact with the surface as not to cause undesired stress in the metal, which inevitably creates a drastic reduction in the quality of the strip. The most critical geometric parameters relating to the rolls are therefore the facing symmetry and centering with respect to the advance line of the metallic strip. At the same time, the system must guarantee a constant load which is adequate for the rheological characteristics of the material deposited, regardless of geometric variables such as thicknesses, linear dimensions of the strip, advance rate and possible thickness faults. Following these requirements, the regulation (especially the initial regulation) of the machine acquires fundamental importance for obtaining the required quality characteristics of the strip.

[0007] Due to the relative novelty of these machines and difficulty in regulation mentioned above, the market offer is extremely uneven with respect to manual regulation machines. In these machines, the positioning operations are effected by a specialized operator observing the cycle described hereunder. In the rest position, the' machine has the two roll-holder sections open, i.e. detached from the advance line of the strip, to allow normal maintenance and preparation operations for the subsequent processing. After engagement, the operator closes the two sections by converging them on skids moved by various kinds of actuators. In this phase, the rolls do not enter directly into contact with the strip but reach a position close to the operating position. Due to the roughness of the operation, the machine operator can be assisted by automatic systems, such as for example a synchronism bar which consists in an automatic system which symmetrically moves the two sections together with respect to a theoretical centre.

[0008] The subsequent phase consists in the fine positioning and optimization of the load for depositing the coating. In this phase, the further convergence, centering, force exerted and final calibration on the strip are run by a second advance system (fine regulation), with independent moving systems (skids and actuators) situated above the first system. Electronic centering aids are also available for this second movement system but, as a result of the critical nature of the operation, these are often deactivated and the operation is completely manual to allow the maximum maneuvering freedom.

[0009] Once the configuration parameters have been defined, the machine is normally capable of exploiting its automatisms for maintaining the conditions established or managing the production transitories, such as opening and closing operations in correspondence with welding cords. The lack of an adequate sensor system however does not allow them to adapt to new conditions that may arise during the processing. This excessive rigidity of the system therefore obviously requires a careful and alert control on the part of the operator which is not compatible with the declared simplicity of the machine.

[0010] A control method for governing the load of the rolls of a machine for applying a coating to a metallic strip is described for example in the document EP 0681510. In this document a retroaction method is defined for governing the load of the rolls, using however the thickness data of the coating deposited which is obviously localized (in this particular case on the lower surface of the strip), presuming a distribution model with a homogeneity which is rarely verified in operating situations.

[0011] As mentioned above, in order to avoid problems relating to the regulation of manually controlled machines, "chem coaters" equipped with automatic regulation systems were introduced. These however are generally manual machines in which the regulation handwheels have been substituted with motors and instrumented with load sensors for controlling the force exerted on the rolls. Machines specifically conceived and developed for a purely automated use cannot in fact be found on the market.

[0012] The main problem of the chem coaters currently available on the market, whether they be manual or automatic, consists in the doubling of the movement systems of the rolls, i.e. the superimposed double-skid configuration for the movement of the calibration and application rolls situated on each side of the metallic strip to be coated.

[0013] This solution in fact leads to a high mechanical and automation complexity, with a consequent increase in the development and construction costs of the machine (consider, for example, the additional masses which must be moved from the main convergence skid). This construction complexity also involves greater demands, in terms of time, personnel and materials, in the case of maintenance interventions on the machine and can finally create complications, with a consequent prolonging of the actuation time, in normal reconfiguration operations during production changes.

[0014] A further problem encountered in current machines consists in the limited autonomy, referring to the incapacity of reacting autonomously to changing operative conditions, that this generation of machine shows when considerable transversal unbalancings are present in the geometry of the strip. The lack, in fact, of an exhaustive detection system of the operating conditions inhibits the electronics installed from completely governing the process, leaving the actions to be taken to the experience of the line operator.

[0015] The velocities in question, however, are so high that even an imperceptible delay, which is very human, in the response can cause significant alterations in the quality of the product (the strip) for extensions in the order of hundreds of meters.

[0016] In some operating conditions, the strip can reach the machine with a perceptively angled side, for example one of its ends wound around the advance axis. This condition causes a non-linear load gradient in the transversal direction of the strip with consequent non-homogeneity in the thickness of the coating deposited. In the automatic machines currently available, the control software adapts inadequately to this condition and, in addition, the configuration based on the double movement system of the rolls (double skid) reduces the rigidity of the mechanical system, increasing this non-homogeneity of the deposit. The control operations and consequent actions are therefore left to the machine operator who acts manually with different set-ups at the ends of the application cylinder, creating an unbalancing of the basic set-ups.

[0017] Even more comprehensibly, in manual machines, the above variations in the configuration, create conditions which cannot be detected and solved automatically by the control electronics, forcing the operators, during the subsequent production change, to waste time in manually re-aligning the geometry of the rolls. This latter operation can only be approximately effected as the manual system does not avail of any type of means for effecting a precise and easy calibration when the machine is running.

[0018] What has been specified so far also applies to what is indicated in the above document EP 0681510 in which tilting skids are observed which must obviously be integrated with an underlying linear movement device for both sections.

[0019] An objective of the present invention is therefore to provide a "chem coater" machine for the continuous application of protection products on a metallic strip in which the movement mechanism of the calibration and application rolls are considerably simplified, with a consequent reduction in the construction costs of the machine itself.

[0020] Another objective of the present invention is to lighten the roll-holder section of the machine, reducing the power requirements installed in the actuators and at the same time increase the response rate to any operating variation with respect to the initial regulation parameters.

[0021] A further objective of the present invention is to increase the overall rigidity of the machine, reducing the susceptibility of the system to deposit defects due to geometrical imperfections of the metallic strip to be coated.

[0022] Yet another objective of the present invention is to reduce the number of parts subject to maintenance of the machine, increasing its intrinsic qualities of maintainability, observability and reliability.

[0023] A further objective of the present invention is to reduce the development, construction and maintenance costs using a single project, the same, for the two side roll-holder sections of the machine. These sections are then installed, with assembly rotated by 180°, at different heights operating directly on the metallic base, much less costly with respect to the machine itself.

[0024] These and other objectives according to the present invention are achieved by providing a simplified machine for the continuous application of protection products on a metallic strip as indicated in claim 1.

[0025] Further characteristics of the invention are specified in the subsequent claims.

[0026] The characteristics and advantages of a simplified machine for the continuous application of protection products on a metallic strip according to the present invention will appear more evident from the following description, relating to a preferred embodiment provided for illustrative and non-limiting purposes, and referring to the enclosed schematic drawings, in which:

figure 1 is a side schematic view of a machine for the continuous application of protection products on a metallic strip according to the known art;

figure 1A is a transversal sectional view along the line A of figure 1;

figure 2 is a side schematic view of a machine for the continuous application of protection products on a metallic strip according to the present invention;' and

figure 2A is a transversal sectional view obtained along the line B of figure 2.

[0027] With particular reference to figure 1, this shows fundamental components of the operative semi-sections of a "chem coater" machine of the known type for the continuous application of protection products on a metallic strip. Each semi-section essentially comprises an application roll 100, capable of transferring the coating material, removed from a containment tank (not shown), onto an advancing metallic strip, and a calibration roll 102, with an axis parallel to that of the corresponding application roll 100.

[0028] Each calibration roll 102 is assembled on a first movement device consisting of two sliding blocks or skids 104, one for each side of the roll 102, sliding axially along respective linear guides 106 in a perpendicular direction with respect to the axis of the rolls 100 and 102, said linear guides 106 being formed on a second movement device, in turn consisting of a pair of sliding blocks or skids 108, on which the application roll 100 is assembled. The skids 108, whose function is to regulate the distance of the application roll 100 from the surface of the continuous strip, slide axially along linear guides 110 envisaged on a third movement device of the semi-section of the machine, consisting of a pair of roll-holder shoulders 112 in turn sliding along guides 114, also visible in the section of figure 1A, integral with the base 116 of the application machine..

[0029] The pairs of skids 104 and 108 of each semi-section are respectively driven by mechanical and/or electrical actuators 118 and 120, activated separately to effect both the reciprocal positioning movements of the two rolls 100 and 102 and the movement of the roll 100 with respect to the continuous strip. In turn, the roll-holder shoulders 112 can also be moved by corresponding actuators to position each entire group consisting of skids and rolls of the same semi-section with respect to the strip to be coated. It is therefore evident that a complex movement system such as that described above is difficult to regulate, whether it be subjected to automatic or manual controls.

[0030] Figure 2, on the other hand, shows the fundamental components of the two operative semi-sections S₁ and S₂, identical to each other, of a machine for the continuous application of protection products on a metallic strip according to the present invention. As previously described for the application machines of the known type, each semi-section, for example S₁, comprises at least one application roll 200, capable of transferring the coating material onto the advancing metallic strip, and at least one calibration roll 202, with an axis parallel to that of the corresponding application roll 200 and in contact therewith under operating conditions.

[0031] The coating material can be removed from a containment tank (not shown) in which the calibration roll 202 is partially immersed, which, in relation to the contact pressure with the application roll 200 and relative rotation rates, determines the quantity of material to be transferred onto the metallic strip. This type of application implies a rotation of the application rolls 200 contrary to the advance direction of the metallic strip and is commonly called "application in reverse". The other possible application, called "forward", with a rotation of the application rolls 200 in the advance direction of the metallic strip, is achieved by feeding the coating material from above directly between the calibration roll 202 and the application roll 200. Also in this case, the quantity of material to be transferred onto the metallic strip is determined by the pressure between the two rolls 200 and 202 and their rotation rate.

[0032] Each application roll 200 of each semi-section is hinged, in correspondence with its ends, onto a pair of moveable skids 204, one for each side of the machine, sliding along linear guides 206 preferably horizontal assembled directly on the metallic base 20.8 of the machine itself. More specifically, as can be clearly seen in figure 2, the two identical semi-sections S₁ and S₂ are installed, by assembling them rotated by 180° with respect to each other, at different heights on the base 208 of the machine, operating directly thereon without the use of additional moveable elements which make the whole movement system more complex and less rigid.

[0033] Each skid 204 is moved by at least one electric servomotor 210 driven by means of an inverter, in order to ensure the automatic and perfectly controlled moving operations of the rolls. The skids 204 unify both the main movement of the group consisting of the rolls 200 and 202, i.e. from the rest or maintenance position to the operating position and vice versa, and also that relating to the operating position, which consists in guaranteeing an adequate penetration of the application rolls 200 with respect to the continuous strip, said operations however only being possible, in machines of the known type, with the double movement of the skids 108 and 112.

[0034] It should be noted that the roll-holder skids 204 of each semi-section S₁ and S₂ can be moved by the respective servomotors 210 either individually, when defects of the strip must be compensated during processing operations, and also contemporaneously, to guarantee a parallel movement of the application rolls 200 with respect to the strip itself.

[0035] Each calibration roll 202, on the other hand, is assembled in a conventional way, on a pair of skids 212 which slide axially, in a substantially perpendicular direction with respect to the axis of the rolls 200 and 202, along respective linear guides 214 situated on the skids 204, so that only the movement relating to the calibration rolls 202 with respect to the application rolls 200 is left to said skids 212.

[0036] In order to limit any possible problems of vibration which could arise during the operative phases and to ensure a perfect positioning of the roll-holder skids 204 without clearances, each of the guides (206) of the machine according to the invention advantageously consists of a double guiding rail (206a, 206b) for each roll-holder skid 204 of each semi-section S₁ and S₂. This expedient ensures a much higher structural rigidity with respect to machines of the known type, both on the advance surface of the strip and that orthogonal thereto, reducing susceptibility to depositing defects of the coating material and therefore guaranteeing a more uniform deposition of the product to be applied to the strip.

[0037] In an embodiment example in which the chem coater is entirely automated, it can be equipped with position sensors, for controlling the opening and closing of the semi-sections S₁ and S₂ at the head of the strip, pressure sensors, capable of monitoring the stress exerted on the rolls 200 and 202 in the preferred directions (axial of the motor and in the direction of the strip), and accelerometers, to control the level of dynamic stress to which the whole structure of the machine is subjected. The above pressure sensors preferably consist of load cells, one for each skid 204, to automatically regulate the application machine, again by means of servomotors 210, in order to obtain a certain load (pressure) on the application roll 200. The constant control of the signals provided at the outlet of the load cells is used to manage the operating position of the application rolls 200 with respect to the strip, with the double purpose of finely regulating the quantity of material deposited and, by changing the winding angle of the strip on the rolls 200, optimizing the mechanical stress absorbed by the application machine.

[0038] Monitoring systems are also envisaged in the manual version of the application machine, which allow a remote control of the machine with a consequent reduction in operators assigned to the production line and increased safety, as the physical presence of a person close to the passage area of the strip is no longer necessary.

[0039] Another important characteristic of the application machine according to the present invention, both in the entirely automated and also in the manual configuration, consists in the control of the accelerations and translation rates of the roll-holder skids 204. This prevents brusque variations in the velocity from causing leakages from the containment tanks and consequent dispersions into the environment of chemical products adopted for the coating of the strip.

[0040] Furthermore, the automatisms envisaged on the machine according to the invention allow the position of the rolls 200 to be controlled, which, together with the velocity control, optimizes the opening and closing times of the rolls on the strip in the passage phase of the welding between two adjacent strips, considerably reducing the length of the non-treated strip and therefore the quantity of waste strip.

[0041] It can therefore be seen that the machine for the continuous application of protection products on a metallic strip according to the present invention achieves the objectives specified above, in particular the simplification of the movement mechanism of the rolls, thus improving the possibility of regulating the machine, also thanks to the use of the sophisticated control electronics, and its structural rigidity.

[0042] The simplified machine for the continuous application of protection products on a metallic strip of the present invention thus conceived can in any case undergo numerous modifications and variants, all included in the protection scope defined in the following claims.

[0043] Furthermore, in practice, the materials used as also the dimensions and components can vary according to specific technical demands.

Claims

1. A simplified machine for the continuous application of coating products on a metallic strip, comprising at least two operative semi-sections (S₁, S₂), each of said semi-sections (S₁, S₂) comprising:

• at least one application roll (200), capable of transferring said coating product, removed from at least one containment tank, onto said metallic strip;

• at least one calibrating roll (202), having an axis parallel to that of said application roll (200) and being in contact therewith under operating conditions of said machine,

said at least one application roll (200) being hinged, in correspondence with its ends, onto at least one pair of moveable skids (204), one for each side of said machine, which slide axially in a substantially perpendicular direction with respect to the axis of said rolls (200, 202) along respective linear guides (206) assembled directly on the base (208) of said machine, characterized in that each of said moveable skids (204) is moved by at least one electric servomotor (210) driven by means of an inverter, and wherein one or more position sensors are provided for controlling the reciprocal distance between the application rolls (200) of each of said semi-sections (S₁, S₂).

2. The machine according to claim 1, characterized in that said two operative semi-sections (S₁, S₂), each consisting of said pair of moveable skids (204), are identical to each other and are assembled, rotated by 180° with respect to each other, at different heights on said base (208) of the machine.

3. The machine according to claim 1, characterized in that each of said calibration rolls (202) is hinged, in correspondence with its ends, onto at least a pair of skids (212) which slide axially along respective linear guides (214) situated on each of said moveable skids (204).

4. The machine according to claim 1, characterized in that each of said linear guides (206) consists of a double guiding rail (206a, 206b) for each of said roll-holder skids (204).

5. The machine according to claim 4, characterized in that said guiding rails (206a, 206b) are substantially horizontal.

6. The machine according to claim 1, characterized in that it comprises one or more pressure sensors capable of monitoring the stress exerted on said application rolls (200) and calibration rolls (202).

7. The machine according to claim 6, characterized in that said pressure sensors consist of load cells, one for each of said moveable skids (204), for automatically regulating said machine, by means of said servomotors (210), in order to obtain a certain load on each of said application rolls (200).

8. The machine according to claim 1, characterized in that it comprises one or more accelerometers for controlling the level of dynamic stress to which the whole structure of said machine is subjected.

Ansprüche

1. Vereinfachte Maschine zur kontinuierlichen Aufbringung eines Beschichtungsprodukts auf einen Metallstreifen, die zumindest zwei betriebsfähige Untereinheiten (S₁, S₂) umfasst, wobei jede der Untereinheiten (S₁, S₂) aufweist:

zumindest eine Auftragwalze (200), die das aus wenigstens einem Vorratstank entnommene Beschichtungsprodukt auf den Metallstreifen zu übertragen vermag,

zumindest eine Kalibrierwalze (202), die eine Achse parallel zu der der Auftragwalze (200) hat und mit dieser unter Betriebsbedingungen der Maschine in Kontakt steht,

wobei die zumindest eine Auftragwalze (200) mit ihren Enden an zumindest einem Paar verschiebbarer Schlitten (204) angelenkt ist, einer für jede Seite der Maschine, die längs zugehöriger Linearführungen (206), welche unmittelbar an der Basis (208) der Maschine montiert sind, axial in einer im Wesentlichen rechtwinkligen Richtung bezüglich der Achse der Walzen (200, 202) gleiten,
dadurch gekennzeichnet, dass jeder der verschiebbaren Schlitten (204) durch wenigstens einen mittels eines Inverters angetriebenen elektrischen Servomotor (210) bewegt wird, wobei einer oder mehrere Positionssensoren zum Kontrollieren des wechselseitigen Abstands zwischen den Auftragwalzen (200) jeder der Untereinheiten (S₁, S₂) vorhanden sind.

2. Maschine nach Anspruch 1,
dadurch gekennzeichnet, dass die zwei betriebsfähigen Untereinheiten (S₁, S₂), die jeweils aus dem Paar verschiebbarer Schlitten (204) bestehen, zueinander identisch sind und um 180° bezüglich einander gedreht auf unterschiedlichen Höhen auf der Basis (208) der Maschine montiert sind.

3. Maschine nach Anspruch 1,
dadurch gekennzeichnet, dass jede der Kalibrierwalzen (202) mit ihren Enden an wenigstens einem Paar Schlitten (212) angelenkt ist, die axial entlang zugehöriger Linearführungen (214) gleiten, welche auf jedem der verschiebbaren Schlitten (204) angeordnet sind.

4. Maschine nach Anspruch 1,
dadurch gekennzeichnet, dass jede der Linearführungen (206) aus einer doppelten Führungsschiene (206a, 206b) für jeden der Walzenträgerschlitten (204) besteht.

5. Maschine nach Anspruch 4,
dadurch gekennzeichnet, dass die Führungsschienen (206a, 206b) im Wesentlichen horizontal sind.

6. Maschine nach Anspruch 1,
dadurch gekennzeichnet, dass sie einen oder mehrere Drucksensoren aufweist, die die auf die Auftragwalzen (200) und die Kalibrierwalzen (202) ausgeübte Belastung zu überwachen vermögen.

7. Maschine nach Anspruch 6,
dadurch gekennzeichnet, dass die Drucksensoren aus Kraftaufnehmern bestehen, einer für jeden der verschiebbaren Schlitten (204) zum automatischen Regeln der Maschine mittels der Servomotoren (210), um eine bestimmte Belastung jeder der Auftragwalzen (200) zu erzielen.

8. Maschine nach Anspruch 1,
dadurch gekennzeichnet, dass sie einen oder mehrere Beschleunigungsaufnehmer zum Steuern des dynamischen Belastungsniveaus aufweist, dem die gesamte Struktur der Maschine ausgesetzt ist.

Revendications

1. Machine simplifiée pour l'application continue de produits de revêtement sur une bande métallique, comprenant au moins deux demi-sections actives (S₁, S₂), chacune desdites demi-sections (S₁, S₂) comprenant :

au moins un rouleau d'application (200), pouvant transférer ledit produit de revêtement, retiré depuis au moins une cuve de stockage, sur ladite bande métallique ;

au moins un rouleau de calibrage (202), ayant un axe parallèle à celui dudit rouleau d'application (200) et étant en contact avec celui-ci dans des conditions de fonctionnement de ladite machine,

ledit au moins un rouleau d'application (200) étant articulé, en correspondance avec ses extrémités, sur au moins une paire de patins mobiles (204), un pour chaque côté de ladite machine, qui coulissent axialement dans une direction sensiblement perpendiculaire à l'axe desdites rouleaux (200, 202) le long de guides linéaires respectifs (206) assemblés directement sur la base (208) de ladite machine, caractérisée en ce que chacun desdits patins mobiles (204) est déplacé par au moins un servomoteur électrique (210) entraîné au moyen d'un onduleur, et dans laquelle un ou plusieurs capteurs de position sont prévus pour commander la distance mutuelle entre les rouleaux d'application (200) de chacune desdites demi-sections (S₁, S₂).

2. Machine selon la revendication 1, caractérisée en ce que lesdites deux demi-sections actives (S₁, S₂), comprenant chacune ladite paire de patins mobiles (204), sont identiques l'une à l'autre et sont assemblées, en étant tournées de 180° l'une par rapport à l'autre, à des hauteurs différentes sur ladite base (208) de la machine.

3. Machine selon la revendication 1, caractérisée en ce que chacun desdits rouleaux de calibrage (202) est articulé, en correspondance avec ses extrémités, sur au moins une paire de patins (212) qui coulissent axialement le long de guides linéaires respectifs (214) situés sur chacun desdits patins mobiles (204).

4. Machine selon la revendication 1, caractérisée en ce que chacun desdits guides linéaires (206) est constitué d'un double rail de guidage (206a, 206b) pour chacun desdits patins de support de rouleau (204).

5. Machine selon la revendication 4, caractérisée en ce que lesdits rails de guidage (206a, 206b) sont sensiblement horizontaux.

6. Machine selon la revendication 1, caractérisée en ce qu'elle comprend un ou plusieurs capteurs de pression pouvoir contrôler la contrainte exercée sur lesdits rouleaux d'application (200) et rouleaux de calibrage (202).

7. Machine selon la revendication 6, caractérisée en ce que lesdits capteurs de pression comprennent des cellules dynamométriques, une pour chacun desdits patins mobiles (204), pour régler automatiquement ladite machine, au moyen desdits servomoteurs (210), afin d'obtenir une certaine charge sur chacun desdits rouleaux d'application (200).

8. Machine selon la revendication 1, caractérisée en ce qu'elle comprend un ou plusieurs accéléromètres pour commander le niveau de contrainte dynamique auquel est soumis l'ensemble de la structure de ladite machine.

Drawing