EP1393904B1 - Rotary press for applying a pattern on a web like substrate - Google Patents

Abstract

The press has a working cylinder (2) bearing embossing plates (16) of patterns of a material to be laid on a strip (14). An anvil cylinder (4) with a periphery is placed such that peripheries are in opposition and spaced apart. A prestress application assembly operates to exert a defined prestress between the two cylinders. Cone-shaped surfaces of contacts adjust a space (13) between the cylinders.

Description

The present invention relates to a rotary press for depositing patterns of a material on a web substrate

The document US Patent 4926666 describes a device that can be used in a stamping machine of the type comprising a working roll and a counter-roll, means for driving the work roll in rotation, means for exerting a predetermined prestressing between said work roll and said counter cylinder and means for adjusting the spacing between said working cylinder and said counter cylinder.

The document EP-A-0469433 discloses a stamping device comprising a working roll and a counter-roll, means for heating the work roll and means for exerting a predetermined prestress between said work roll and said counter roll.

The advantage of this type of press compared to the flat stamping lies in the fact of being able to work continuously at a substantially higher speed than with the flat stamping. The gases resulting from the vaporization of the wax which is between the polyester carrier strip and the metal film are more easily evacuated and the consumption of web material to be deposited can be substantially reduced. However, this material, generally consisting of a laminate consisting of four layers, a polyester support strip, a wax layer, a metal film and a glue layer, is expensive.

In order to reduce the consumption of strips of material to be optimally deposited, it is necessary not only to use a rotary press equipped with a working roll bearing pictures of the patterns of said material to be deposited, but it is also necessary that the strip of material does not pass through the rotary press according to a traditional trajectory, but in an almost rectilinear trajectory. Indeed, with the traditional trajectory, the strip of material to be deposited and the strip substrate on which the pattern of the material has been deposited remain against each other and are pressed against the cylinder against a certain angle of the counter-cylinder after being passed between the cylinders of the rotary press, to increase the contact time and facilitate the attachment of the pattern deposited on the substrate. This traditional way of passage substantially limits the possibility of saving material tape to deposit, insofar as the substrate and the strip of material must move together.

However, to allow optimum economy of carrier band consumption, it is necessary to stop or even remove a certain length of the support strip between two pattern deposits on the strip substrate. This is only possible if the support strip of the material to be deposited and the substrate are in contact almost only on a line corresponding to the respective generatrices of contact between the two rolls of the rotary press or at least over a longitudinal distance of the substrate low enough to allow their relative displacement as soon as they are no longer clamped between the rolls of the press, that is to say between two successive transfers of the patterns on the strip substrate. This is only possible if the strip of material to be deposited has a substantially rectilinear trajectory.

Given these constraints and in particular the very short contact time between the support strip of the material to be deposited and the strip substrate, it is necessary that the average temperature of the work roll of the rotary press is higher and the temperature differences. allowable to be narrower than in flat stamping, as well as in the case of the rotary press with traditional passage, which was discussed above.

So that these very small tolerances can be satisfied, not only must the temperature be precisely controlled, but it is also necessary that the pressure exerted between the rolls of the press and the spacing between these cylinders to allow the passage of the substrate in band, the support strip of the material of the pattern to be deposited and the snapshot are also adjusted precisely, without the setting of one influences the setting of the other. It is also important that the clearance between the cylinders in which the substrate passes, the support band of the material to be deposited and the one or more plates is constant and does not vary as the temperature of the working cylinder increases.

The object of the present invention is to provide a solution making it possible to contribute, at least to a certain extent, to an optimal use of the material support strip to be deposited on a strip substrate while maintaining the adjustment of the parameters of the substrate. operation of the press.

For this purpose, the present invention relates to a rotary press for depositing patterns of a material on a web substrate, as defined in claim 1.

With this rotary press, the adjustment of the prestressing exerted between the rolls of the press, to effect the deposition of patterns on a strip substrate from the material carried by the support strip, is totally independent of the adjustment of the clearance between the rolls. , so that these two parameters can be adjusted precisely. It is all the more important that the support strip has substantially a straight path through the rolls, minimizing the contact time between the two belts during the pattern deposition operation. However, as explained above, the rectilinear or substantially rectilinear passage of the support strip of the material to be deposited through the rolls of the press is the condition to be fulfilled to allow modulation of the speed of this support strip between the deposit. two successive patterns and thus an optimal use of this support band.

• La figure 1 est une vue en élévation de cette forme d'exécution;
• la figure 2 est une vue schématique selon la ligne A-A de la fig. 1;
• la figure 3 est une vue partielle agrandie en coupe diamétrale du cylindre de travail vu non coupé sur la figure 2;
• la figure 4 est une vue partielle très agrandie de la partie X de la figure 3;
• la figure 5 représente un premier exemple de fixation d'un cliché sur le cylindre de travail et
• la figure 6 représente un deuxième exemple de fixation d'un cliché sur le cylindre de travail.

Other features and advantages of the present invention will become apparent from the following description which will be made in connection with the accompanying drawing which illustrates, schematically and by way of example, an embodiment of the rotary press object of this invention.

• Figure 1 is an elevational view of this embodiment;
• Figure 2 is a schematic view along the line AA of FIG. 1;
• Figure 3 is an enlarged partial view in diametral section of the working cylinder seen uncut in Figure 2;
• Figure 4 is a greatly enlarged partial view of part X of Figure 3;
• FIG. 5 represents a first example of fixing a plate on the working cylinder and
• Figure 6 shows a second example of fixing a plate on the working cylinder.

The rotary press according to the invention comprises a frame 1 on which is mounted a working cylinder 2, the respective ends of which are fixed to the frame 1 by fixing members 3, each provided with a clamping screw 3a. A counter-cylinder 4, parallel to the working cylinder 2, is pivoted freely on a rocker 5 pivotally mounted on the frame 1 about an axis 6 parallel to the axis of the cylinders 2 and 4. A jack 7 is used to press the against cylinder 4 against the cylinder working piece 2, with a predetermined prestressing force, via a lever 7a acting on the rocker 5 and able to increase the pressure exerted by the jack 7.

FIG. 2 shows how the pressure of the jack 7 is transmitted between the working roll 2 and the counter-roll 4. This pressure is symbolized by two arrows F ₁ , F ₂ . The counter-cylinder 4 is pivotally mounted around two coaxial half-shafts 8 by ball bearings 9. Two cylindrical rings 10 are mounted on two eccentric portions 11 of the respective half-shafts 8 by ball bearings 12. The cylindrical rings 10 are in rolling contact with two cylindrical surfaces 2a integral with the working cylinder 2.

These cylindrical rings 10 and the cylindrical surfaces 2a, forming the contact surfaces between the working cylinder 2 and the counter-cylinder 4, allow to transmit the preload exerted by the cylinder 7 while providing a clearance 13 between the working cylinder 2 and the counter-cylinder 4 for the passage of a strip substrate 14 and one or more support strips 15 of the material of the patterns to be deposited on the substrate 14. This set 13 is chosen so that the prestressing exerted and the temperature of the working roll 2 make it possible to heat-transfer the patterns of the material of the support strip 15 onto the strip substrate 14 during the passage of the plates 16 in the clearance 13 separating the two rolls 2, 4.

One of the cylindrical rings 10 is integral with a toothed wheel 10a which meshes with a toothed wheel 2b integral with the working roll 2. The toothed wheel 10a is engaged with a drive motor (not shown) via an LM motor link.

The outer ends of each half-shaft 8 are integral with a toothed wheel 17 in engagement with an endless screw 18 integral with a conical return 19, connected to a handle (not shown) for adjusting the clearance 13; it is also possible to influence the clearance 13 only on one side of the roll 2 and to create a slightly progressive clearance 13 across the width of the strip 14. This system can also be replaced by two motors each acting on a screw without end 18. The rotation of the half-shafts 8 of a certain angle rotates the eccentrics 11 about the axis of the coaxial half-shafts 8, thus modifying the clearance 13 between the working roll 2 and the counter-roll 4, without modifying the value of the prestress exerted on the cylinders 2 and 4 via the cylindrical contact surfaces 2a and 10.

For depositing and fixing the patterns of the material of the support strip or strips 15, cut and heated by the plates 16 of the working roll 2 on the strip substrate 14, the outer layer of the support strips 15, adjacent to the substrate in strip 14 on which the patterns are deposited, is formed of a thermosetting glue. This is the reason why the working cylinder 2 must comprise heating means.

FIG. 3 shows the interior of the working cylinder 2 which comprises a heating enclosure 20 formed by a tubular part 21 in thermal contact with the working cylinder 2. This heating enclosure 20 is closed at both ends by flanges 22, whose center is secured to a pivoting cylinder 23 coaxial with the axis of the working cylinder 2. One of these pivot cylinders 23 (the left one in Figure 3) is traversed by an axial conduit 24 divided into two concentric ducts 24a, 24b by a tubular wall 25a of a rotating connection 25, for connecting the heating chamber 20 to a heating oil circuit (not shown). The inside of the heating chamber 20 is divided into several compartments by concentric tubular partitions 26, provided with perforations 26a to form a reciprocating flow of the heating fluid between the inlet channel 24a and the channel 24b output.

For mechanical reasons and heat transfer, the tubular portion 21 of the heating chamber 20 and the closing flanges 22 of the ends of these enclosures are made of different metals such as steel for the external parts such as the part external cylindrical working cylinder 2, and closing flanges 22 and aluminum for the heating chamber 20. To prevent the formation of a space between the contact surfaces 21a, 22a of these two parts 21, 22 , which would modify the adjustment of the clearance 13 between the cylinders 2 and 4, these surfaces 21a, 22a are of conical shape with a half angle α at the top of these conical contact surfaces 21a, 22a corresponding to the angle of the hypotenuse d a right-angled triangle whose other sides correspond to the longitudinal thermal expansion of a given point of one of said contact surfaces (21a, 22a) relative to the median axis M of said heating chamber 20 at a given temperature e, respectively at the radial expansion of this same point at the same temperature, so that the contact surfaces 21a, 22a remain contiguous regardless of the temperature of the cylindrical heating chamber 20. In FIG. passing the line AC of Figure 4 by the center 28 of the working cylinder 2, the angle α is determined for each case in particular.

Indeed, if we examine, with reference to Figure 4 what happens during a temperature rise ΔT, observing two adjacent points, one located on the conical surface 22a of the flange 22, the other on the conical surface 21a of the tubular part 21 which are, at the temperature T, both of which coincide at C on the explanatory diagram of FIG. 4, it can be seen that at the temperature T + ΔT, the point situated on the conical surface 22a of the flange 22 has moved to B which is the result of the radial expansion dr ₂₂ of this point and its longitudinal expansion dl ₂₂ relative to the median axis M of the heating chamber 20.

In fact, this resultant is the hypotenuse of a right triangle whose sides dr ₂₂ and dl ₂₂ are proportional to radial expansion, respectively longitudinal, which depend on the radial respectively longitudinal dimensions of a given point. These radial and longitudinal dimensions vary according to the coefficient of expansion of the material, but their ratio and thus the angle of the hypotenuse, is constant. Thus, the same adjacent point taken on the conical surface 21a of the tubular part 21 of the heating chamber 20, at the same point C of FIG. 4, at the temperature T, is found at point A at the temperature T + ΔT and that this point A is on the hypotenuse of a right triangle whose other sides correspond to the radial expansion dr ₂₁ , respectively to the longitudinal expansion dl ₂₁ of the tubular portion 21 at this point C. However, the ratio between these sides dr ₂₁ and dl ₂₁ remains the same as between the sides dr ₂₂ and dl ₂₂ corresponding to the expansion on the conical surface 22a of the closure flange 22, so that the angle α of the hypotenuse is the same. Thus, with these conical contact surfaces 21a, 22a, no play is formed as a result of temperature variations, even if the expansion coefficients are different for the two materials and the outer surface of the working cylinder 2 remains stationary relative to its axis of rotation, since no clearance has formed between these conical surfaces 21a, 22a, so that the clearance 13 between the working cylinder 2 and the counter-cylinder 4 remains constant. Under these conditions, even if this game 13 was set while the press was cold, it remains the same when the working cylinder 2 is hot.

Advantageously, two O-rings 27 are disposed near the two edges of the conical contact surface 22a of the flanges of closing 22 with the adjacent conical surface 21a of the tubular portion 21 of the heating chamber 20.

An important aspect is to achieve a correct heat transfer (thermal power) through the 16 shots of the cylinder 2. Note the following facts: The only way to influence the transfer of energy through the cliché per millisecond is to increase the temperature and / or the flow rate of the fluid delivered by the heating means. Depending on the pattern of the shot, different temperatures may be desirable. Then, the representative temperature of 220 ° C will cause significant radiation loss, heat the surroundings, so this is an unwanted phenomenon.

To improve the situation, various measures are proposed. The faces 29 not covered with images of the tool 2 may be covered with an insulating layer, promoting the passage of available heat through the plates 16 (Figures 5, 29b). To manage the passage of heat selectively through each plate 16, the following measurements will be used in whole or in part (see FIG. 5): a plate 16 may be inserted and fixed by suitable means 30 in a carrier tube 31 which may be slipped on the work roll 2. Parts 31 and 2 can also be the same. The plate 16 may be provided with blind holes 32, variable dimensions and distributions, connected or not by holes 33 promoting the escape of air during temperature changes. This will create air pockets and effective brakes to the passage of heat. The images can be placed on shims 34, which will incidentally allow to set their active radius Ra in small values. These shims 34 may or may not be provided with holes of new distributions and variable diameters. It can also be blind holes. The images of the holes 32, 35 may be aligned or not. The shim 35 may also be made of insulating material, resistant to temperature. It is also possible to envisage the use of fretted materials (pressed from powder). In summary, we can slow the passage of energy through one or more clichés compared to others.

Another difficulty lies in the fact that the plates 16 are often made of brass, the tube 31 made of steel. The fixation must therefore be capable of holding the differential expansions.

Figure 5 also shows a proposed arrangement for this fixation. A spacer 30, made of insulating material or not, makes it possible to wedge the plate 16 positively against the left shoulder 36, ensuring its exact repositioning in case of alterations. The controlled elasticity of the workpiece 30 permits differential thermal expansions between the portions 31 and 16.

FIG. 6 shows that it is possible to provide fixing variants in which a change in thickness of the shim 34 does not cause angular displacement of the plate 16. This is achieved by proper orientation of the reference face 37. This orientation , parallel to the central line 38 of the plate, however, leads to additional fixation, for example screw 39.

Claims (10)

1. Rotary press to lay patterns of a material on a strip substrate (14), comprising a working cylinder (2) holding embossing dies (16) of patterns of said material to be laid and an anvil cylinder (4), means (2b, 10a, LM) for driving the working cylinder (2) into rotation, means for heating and monitoring temperature (20) of this working cylinder, means (7, 7a, 2a, 10) for exerting a defined prestressing between said working cylinder (2) and said anvil cylinder (4), free rolling means (9) between said anvil cylinder (4) and its pivoting shaft (8), and means (10, 11, 17, 18, 19) for adjusting the spacing (13) between said working cylinder (2) and said anvil cylinder (4) being independent from said means (7, 7a, 2a, 10) for exerting said defined prestressing.
2. Press according to claim 1, in which the pivoting axis of said working cylinder (2) and said anvil cylinder (4) are linked, respectively with a frame (1) and with a rocking member (5) whose pivoting axis to said frame (1) is parallel to the one of said cylinder and anvil cylinder (2, 4), and in which a jack (7) exerts said prestressing on said rocking member (5) via a lever (7a).
3. Press according to claim 1, in which said spacing (13) between the working cylinder (2) and the anvil cylinder (4) is determined by at least one cylindrical part (2a) linked with said working cylinder (2) in contact with at least one cylindrical part (10), being independent from said anvil cylinder (4) and mounted pivoting on a portion (11) of the pivoting shaft (8) of this anvil cylinder (4), eccentric to the rotation axis of said anvil cylinder (4), means (17, 18) being provided for adjusting the angular position of said eccentric portion (11) of the pivoting shaft (8), as a function to desired spacing (13) between said working cylinder (2) and said anvil cylinder (4).
4. Press according to claim 3, in which said working cylinder (2) comprises two cylindrical parts (2a) located on either side of this working cylinder near to its ends, respectively in contact with two cylindrical parts (10), being independent from said anvil-cylinder (4) and mounted pivoting respectively on two eccentric portions (11) of the pivoting shaft (8) of this anvil cylinder (4), located on either side of this anvil-cylinder (4), each of said eccentric portions (11) of said pivoting shaft (8) being associated with independent means (17, 18) for adjusting their angular positions.
5. Press according to one of the preceding claims, in which said heating means comprises a cylindrical enclosure (20) in thermal contact with the external tubular wall of said working cylinder (2), concentric tubular partitions (26) provided with communication openings (26a) dividing said enclosure (20) into a central chamber surrounded with concentric annular chambers, two flanges (22) closing the respective ends of said annular chambers, feeding lines (24a), respectively axial exhaust lines (24b), connecting said enclosure (20) to a source of heating fluid, cone-shaped contact surfaces (21a, 22a) between said respective flanges (22) and the cylindrical wall (21) of said heating enclosure (20), the half angle at the top (α) of these cone-shaped contact surfaces (21a, 22a) corresponding to the hypotenuse angle of a right-angle triangle whose other sides correspond to the longitudinal thermal expansion (dl₂₁, dl₂₂) of a given point of one of said contact surfaces (21a, 22a) with respect to the median axis (M) of said heating enclosure (20) at a given temperature, respectively to the radial expansion (dr₂₁, dr₂₂) of this same point at the same temperature, so as to maintain said contact surfaces (21a, 22a) joined whatever temperature in said heating enclosure (20).
6. Press according to claim 5, in which the wall of said heating enclosure (20) and said flanges (22) are made of materials with respective different expansion coefficient.
7. Press according to one of the preceding claims, where the energy transfer is slowed down in useless zones located between embossing dies (16) by isolating elements (29b).
8. Press according to one of the preceding claims, in which the heat transfer through the embossing dies can be slowed down by appropriate holes, structures and machining inside the embossing dies, or by blocks under the embossing dies, isolating or not, provided with blind or through holes or not, said blocks being also provided as hoops or compounds, of sandwich type
9. Press according to claim 8, in which the blocks have a spring function so as to compensate possible errors of out-of-round of the stamping tool.
10. Press according to one of the preceding claims, in which the embossing dies are fastened by blocks in profile shape along the tool generating lines, these profiles having at least one sloped face positioning with accuracy the embossing die and in a reproducible manner not only in radial but also angularly against a reference face of the holding tool (36), these profiles can be made of elastic material, isolating or not, they can be of an entire or partial length of a tool generating line.

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