METHOD FOR APPLYING A PRODUCT BY ROLLER AND APPLICATION SYSTEM

Abstract

A method for applying a product by roller on a surface of a substrate (112) transported horizontally with respect to an application head (111, 111) is discloses. The method includes moving the application head (111, 111) immediately from a lowered position of the application head (111, 111), wherein the application roller (122, 122) applies the product in a predetermined position of the surface of the substrate, to a raised position of the application head (111, 111), wherein the application roller (122, 122) does not apply product; or vice versa. An application system using the method for applying a product by roller is also disclosed.

Claims

1. A method for applying a product by roller on a surface of a substrate (112) transported horizontally with respect to an application head (111, 111), wherein the method comprises moving the application head (111, 111) immediately from a lowered position of the application head (111, 111), wherein the application roller (122, 122) applies product in a predetermined position of the surface of the substrate, to a raised position of the application head (111, 111), wherein the application roller (122, 122) does not apply product; or vice versa.

2. The method for applying by roller according to claim 1, wherein the predetermined position of the surface of the substrate (112) corresponds to a leading edge (118) of the substrate (112) or a trailing edge (119) of the substrate (112).

3. The method for applying by roller according to claim 1, wherein a first predetermined position corresponds to the leading edge (118) of the substrate (112) and a second predetermined position corresponds to the trailing edge (119) of the substrate (112).

4. The method for applying by roller according to claim 1, further comprising a plurality of predetermined positions of the surface of the substrate (112).

5. The method for applying by roller according to claim 1, wherein the application head (111, 111) stays in the same lowered position between consecutive predetermined positions.

6. The method for applying by roller according to claim 1, wherein the application head (111) is able to be actuated in reverse, such that the application roller (122) applies product in the direction opposite from the transport direction of the substrate (112) towards the application head (111).

7. The method for applying by roller according to claim 1, wherein the movement of the application head (111, 111) is alternating between lowered positions and raised positions.

8. The method for applying by roller according to claim 7, wherein the movement alternating between two consecutive lowered positions is immediate.

9. The method for applying by roller according to claim 7, wherein the period of the movement alternating between two consecutive lowered positions is preferably less than or equal to 1.0 seconds.

10. A system for applying a product by roller on a substrate (112), comprising: an application head (111, 111) comprising an application roller; a transport device (124) for transporting the substrate (112) horizontally with respect to the application head (111, 111); an actuator (113, 113) for moving the application head between a lowered position and a raised position, and vice versa; a position detector (115) of the substrate (112) with respect to the application head (111, 111); and a microprocessor (116) configured to command the method according to claim 1, receiving from the position detector (115) a signal for detecting the position of the substrate (112) and sending an actuation signal to the actuator (113, 113) in order to move the application head (111, 111) in a predetermined position of the substrate (112).

11. The system for applying a product by roller on a substrate (112) according to claim 10, wherein the application head (111, 111) comprises a dosing roller (121, 121).

12. The system for applying a product by roller on a substrate (112) according to claim 10, wherein the actuator (113, 113) comprises a connecting rod and crank mechanism, wherein the rod moves the application head (111, 111) when the crank is turned by a motor.

13. The system for applying a product by roller on a substrate (112) according to claim 10, wherein the actuator (113, 113) comprises a servomotor for rotating the crank.

14. The method for applying by roller according to claim 9, wherein the period of the movement alternating between two consecutive lowered positions 0.5 seconds.

15. The method for applying by roller according to claim 9, wherein the period of the movement alternating between two consecutive lowered positions 0.1 seconds.

Description

DESCRIPTION OF THE FIGURES

[0031] A more detailed explanation is given in the description that follows and which is based on the attached figures:

[0032] FIG. 1a shows a schematic profile view of a machine for applying varnish comprising two application heads, one in normal operation and the other in reverse. In this sequence for applying varnish, the moment when the application roller of the head in reverse impacts the leading edge can be seen.

[0033] FIG. 1b shows the sequence for applying varnish wherein the ridge generated on the leading edge by a machine of the state of the art once varnish has been applied at the beginning of the substrate can be seen.

[0034] FIG. 1c shows the sequence for applying varnish wherein both the ridge generated on the leading edge, as well the one generated on the trailing edge by a machine of the state of the art once varnish has been applied on all of the substrate can be seen.

[0035] FIG. 2 shows a schematic profile view of a system for applying product with an application head comprising an application roller in reverse and with a dosing roller, at the moment when the application head is in the lowered position prior to the contact with the substrate.

[0036] FIG. 3 shows a schematic profile view of a system for applying product with an application head in reverse, at the moment when the application head is being raised to the raised position thereof from the lowered position thereof prior to the contact with the substrate, the actuator being in the position thereof of one fourth of the alternating movement.

DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention relates, as mentioned previously, to a method for applying a product on a substrate (112) and to the system using said method.

[0038] FIGS. 1a, 1b and 1c show the sequence for applying varnish of an application system corresponding to varnishing machines comprising two consecutive heads, of which in the first application head (111) the first application roller (122) rotates in the same direction as the advance of the substrate (112) and the second application head (122) rotates in reverse, i.e. in the direction opposite from the movement of the substrate (112). In this sequence, the ridge generated both on the leading edge (118) and on the trailing edge (119) of the substrate can be seen, which is produced in the varnishing machines of the state of the art. In this type of machine, the substrate (112) is transported thanks to conveyor belts or transport rollers (124).

[0039] In relation to this type of application heads (111, 111), dosing rollers (121, 121) are arranged which, according to the rotation thereof and the gap therebetween and the applicators in the contact area therebetween, contribute larger or smaller amounts of varnish, in order to deposit it on the surface of the application roller (122, 122). This application roller (122, 122) has an outer surface made of rubber which contributes to the adhesion of the varnish dosed by the dosing roller (121, 121).

[0040] In this method of the state of the art, the varnish is applied on the substrate (112), it staying between the application roller (122, 122) and a counter-pressure roller (123, 123) which is kept stationary with respect to the application roller (122, 122). Therefore, a first thin layer of varnish is applied by the first application roller (122) and the corresponding counter-pressure roller (123) thereof. Next, a thicker layer of varnish is applied and the smoothing is produced by the action of the second application roller (122) which acts in the direction opposite from the advance of the substrate (112).

[0041] However, in the deposition of the varnish by both the first application roller (122) and the second application roller (122), an accumulation of varnish is produced on the leading edge (118) and trailing edge (119) of the substrate (112). This accumulation occurs either due to excessive deposition of varnish in these predetermined areas, or due to the impact of the varnish layer adhered to the outer surface of the application roller (122, 122) when it impacts the leading edge (118) or due to the runoff of the varnish smoothed by the applicator in reverse on the trailing edge. In the latter situation, the defect produced by the accumulation of varnish is more apparent.

[0042] Therefore, the object of the invention is to remove these types of excess or ridges, which are visible on the substrate (112) of FIG. 1c. To do so, the system and the method for applying product of the invention are used.

[0043] FIG. 2 shows a preferred embodiment of the system for applying varnish of the invention. In this case, the application head (111) acts in reverse.

[0044] Thus, in a first moment, for the case of systems with two consecutive application heads, wherein an application head (111) acts normally and the other application head (111) acts in reverse, a position detector (115) detects the position wherein the substrate (112) is located in the horizontal movement thereof. Subsequently, a microprocessor (116) receives a detection signal of said position of the substrate (112) and sends an actuation signal to the actuator (113) in order to move the application head (111) coinciding with a predetermined position of the substrate (112).

[0045] In a preferred embodiment indicated for substrates wherein high grammages of varnish are applied, initially said predetermined position coincides with the leading edge (118) of the substrate (112). The actuator (113) receives the actuation signal and moves a first application head (111) immediately before the contact of the first application roller (122) with the leading edge (118) of the substrate (112). This initial movement is produced in the event that the application head (111) is in the usual lowered position, although it could be the case that the application head (111) was initially in the raised position.

[0046] This first roller corresponds to the application roller (122) which rotates in the same direction as the movement of the substrate (112). Together with it, the corresponding dosing roller (121) thereof also moves, both being integral to the application head (111). In order to perform this movement to the raised position, the actuator (113) comprises a connecting rod and crank mechanism. The connecting rod moves the first application head (111) from the lowered position to the raised position wherein the first application roller (122) does not apply varnish.

[0047] The operation of the connecting rod and crank mechanism (113) of the actuator is conventional. The application head (111, 111) is fastened to the bed of the machine through a rotation point, with respect to which it pivots in order to raise and lower. The raising and lowering is provided by a connecting rod fastened, on one side, to one end of the head, and on the other side to a crank, which is an eccentric shaft. By rotating the eccentric shaft, the connecting rod provides the rotation of the head, with respect to the rotation point thereof, and it is raised or lowered. Thus, in the lowered position, the eccentric shaft will be located in the position visible in FIG. 2, in order to subsequently be raised until the eccentric shaft is in the upper position of the circumference. FIG. 3 shows said shaft in an intermediate raised position prior to the upper position, wherein product is no longer applied given that there is no contact with the substrate (112).

[0048] As seen in FIG. 3, the actuator (113), and correspondingly the application head (111), is located in the mentioned intermediate raised position wherein varnish is no longer applied. Afterwards, the crank continues moving to the initial position thereof such as the one indicated in FIG. 2, in order to move the first application head (111) to the lowered position thereof. In this manner, when the leading edge (118) of the substrate is aligned with the first application roller (122), it, in a synchronised manner, is located in the lowered position in order to coincide with the edge of the leading edge (118) on top. Thus, the application of varnish by the first application roller (122) starts at that same time, preventing the formation of the ridge and also preventing the impact of the substrate (112) against the rubber of the outer surface of the application roller (122).

[0049] This movement moving from the lowered position to the raised position and back to the lowered position corresponds to a period of the alternating movement of the connecting rod and crank mechanism of the actuator (113). The period of the movement alternating between two consecutive lowered positions is preferably less than or equal to 1.0 seconds, preferably 0.5 seconds and more preferably 0.1 seconds. In this manner, an immediate movement of the application roller (122) is achieved which does not affect the movement of the substrate (112) and, therefore, the production is increased by decreasing the gap between parts and increasing the feed rate. This immediate movement is achieved thanks to a servomotor comprised in the actuator (113) in order to rotate the crank. It will be beneficial for the continuous application of varnish to several consecutive substrates, wherein that alternating movement will coincide with the movement from a lowered position of the application roller (122) coinciding with the trailing edge (119) of a substrate to a raised position, and from that raised position to a lowered position coinciding with the leading edge (118) of the following substrate (112).

[0050] Once a first thinner layer of varnish has been applied by the first application roller (122), sometimes it may be necessary to apply a second thicker layer and then smooth the varnish in order to achieve a better finish. To do so, varnish is applied with a second application roller (122) the rotation direction of which is opposite from the movement of the substrate (112) and which is called reverse, represented in FIG. 2. Said second application roller (122) is comprised together with the corresponding dosing roller (121) thereof in a second application head (111). In this case, each application head (111, 111) will be independent, for which reason they will act independently one after the other.

[0051] The manner of actuation is the same as with the first application head (111). Once the position of the substrate (112) has been detected, the microprocessor (116) sends an actuation signal to the actuator (113). Said actuator (113) corresponding to the second application head (111) moves the second application head (111) from the lowered position to the raised position immediately before the second application roller (122) impacts against the leading edge (118).

[0052] The second application roller (122) moves once again from the raised position thereof wherein it does not apply varnish to the lowered position coinciding with the edge of the leading edge (118). Then, the application of the second layer of varnish and the smoothing produced by the rotation opposite from the movement of the substrate (112) by the second application roller (122) are started.

[0053] Just like with the first roller (122), the alternating movement of the actuator (113) corresponding to the second application roller (122) preferably has a period of alternating movement of less than or equal to 1.0 seconds, preferably 0.5 seconds and more preferably 0.1 seconds. Thus, an immediate movement of the second application roller (122) is achieved without affecting the movement of the substrate (112) and, therefore, the production is increased.

[0054] Next, the varnishing of the entire surface of the substrate (112) is produced until the first head (111) reaches the trailing edge (119). At this time, the microprocessor (116) receives a signal from the position detector (115) and orders the actuator (113) of the first application head (111) so that it moves to the raised position. This movement is performed immediately such that the first application roller (122) stops applying varnish and the varnish is prevented from overflowing on the trailing edge avoiding the appearance of the ridge on the trailing edge (119).

[0055] Moments later, when the second application head (111) approaches the trailing edge (119), in the same manner, the actuator (113) corresponding to the second application head (111) moves the application roller (122) to the raised position thereof at the moment that it coincides with the edge of the trailing edge (119).

[0056] The result is a varnished substrate without ridges and with an excellent finish.

[0057] If, for design reasons, it were necessary to perform a discontinuous varnish, it would proceed in the same manner. In this case, at the end of the first varnishing area the application head (111, 111) would move to the raised position in order to stop applying varnish immediately once the predetermined position wherein the substrate is free of varnish has been detected. Moreover, at the beginning of the next varnishing area, the application head (111, 111) would move to the lowered position coinciding with said varnishing starting point. In this manner, high-speed and precise varnishing is achieved by means of a system for applying product with simple manufacturing.