Calender and method for processing web-like material

Abstract

Calender for processing web material, comprising a structure for supporting two heated rollers forming an impression line, wherein each roller has surface projections (RR) and, in the operating setting of the calender, the projections of one roller are diametrically opposite to the projections of the other roller, each roller rotates around its own axis with a predetermined angular speed, the rollers are heated by heating means, and each roller is subjected to an axial elongation as a result of the heating of the heating means. The calender comprises detection means (E1, E2; IS) adapted to detect the axial elongation of each roller, and a programmable control unit (UCP) connected to the detection means and to the heating means. The control unit is programmed to determine the difference between the axial elongations of the rollers and to emit an alarm signal in the event that the absolute value of this difference is greater than a limit value.

Description

Technical Field

[0001] This invention relates to a calender and method for processing web-like materials.

[0002] More specifically, the calender and method according to the invention relates to processing web-shaped materials by means of heated rollers. Background Technology

[0003] US3507943 describes the processing of web-like materials, particularly nonwoven fabrics (TNT), and illustrates a system comprising a calender formed by two heated embossing rollers that define an embossing line (nip) through which a web of TNT-type material containing fibrous thermoplasticity passes. The material passing through the embossing line between the two rollers undergoes combined pressure and heat, which determines changes in the arrangement and physical state of the fibers contained within the material itself. Specifically, depending on the pressure applied by the rollers to the processed material, the operating temperature of the rollers, the thickness and composition of the material, and the surface finish of the rollers, deformations corresponding to predetermined patterns can be formed on the material. Other systems including calenders using heated rollers to process TNT are described in US4005169 and WO2020 / 183504.

[0004] The material being processed passes between the calender rolls, which can be arranged in a so-called "tip-to-tip" configuration, in which the protrusion or "tip" of one calender roll must always correspond to the protrusion of another calender roll, i.e., the two rolls must always be synchronized.

[0005] The disadvantage of this type of calender is that the rolls are prone to losing axial phase during use, which means that the produced products do not meet the production specifications, thus causing economic losses. Summary of the Invention

[0006] The main objective of this invention is to provide a system that can eliminate or at least significantly reduce the aforementioned drawbacks.

[0007] According to the present invention, the above results have been achieved by adopting the concept of manufacturing a calender having the features described in this application and implementing an operation method having the features described in this application.

[0008] The present invention eliminates, or at least within predetermined limits, the loss of axial phase in the engraving rollers of a calender used for heat treatment of rolled materials, resulting in significant economic benefits related to reducing the production of non-conforming materials. Furthermore, from both a structural and functional perspective, the control mechanism incorporated in the calender according to the invention is a relatively simple mechanism, and it can be easily installed on existing calenders. Attached Figure Description

[0009] These and other advantages and features of the invention will become more apparent to each person skilled in the art from the following description and accompanying drawings, which are provided by way of example and not intended to be limiting. In the drawings:

[0010] · Figure 1 A schematic side view showing the calender according to the invention in the operating position;

[0011] · Figure 2 A schematic side view showing the calender according to the invention with the rolls (R1, R2) in the released position;

[0012] · Figure 3 A schematic front view of a calender according to the present invention;

[0013] · Figure 4 Indicates along Figure 3 A cross-sectional view of line CC;

[0014] · Figure 5 Indicates along Figure 3 A cross-sectional view of line DD;

[0015] · Figure 6 and Figure 7 The levers (308) and (310) in the operating position are schematically shown;

[0016] · Figure 8 and Figure 9 The schematic diagram shows the operating position. Figure 9 ) and in the position where the roller is released ( Figure 8 ) rod (316);

[0017] · Figure 10 and Figure 11 These are two diagrams illustrating the forces acting on the rolls of the calender shown in the previous diagram;

[0018] · Figure 12 and Figure 13 These are two perspective views of a calender according to the present invention;

[0019] · Figure 14A express Figure 11 The calendering machine, with some parts omitted to better highlight the others;

[0020] · Figure 14B for Figure 12 Detailed images;

[0021] · Figure 15 express Figure 14A A schematic horizontal cross-sectional view of the group to highlight the internal structure of the calender rolls;

[0022] · Figures 16A to 16C for Figure 15 Enlarged detail image;

[0023] · Figure 17 This represents a schematic horizontal cross-sectional view of the calender shown in the previous figure;

[0024] · Figure 18A and Figure 18B These are two detailed drawings, showing the engagement positions on the pins of the rollers. Figure 18A ) and disengagement position ( Figure 18B The joint G1 of the calender is provided, wherein the encoder (E1) is arranged to detect the axial elongation of the roll (R1) of the calender.

[0025] · Figure 18C for Figure 18A Detailed images;

[0026] · Figure 19A and Figure 19B These are two diagrams showing the opening and closing of valve (108) for introducing heated fluid into the rolls of the calender shown in the previous diagram;

[0027] · Figure 19C and Figure 19D These are two cross-sectional views of the two ends of a calender roll;

[0028] · Figure 20A and Figure 20B These are two views of a calender according to another embodiment of the invention, wherein each roller is driven by its own motor;

[0029] · Figure 20C for Figure 20B Detailed images;

[0030] · Figure 21 The illustration shows another modification to the implementation of the present invention;

[0031] · Figure 22 This is a simplified block diagram relating to a possible method for controlling the heating of rolls in a calender according to the present invention;

[0032] · Figure 23 This is a simplified block diagram relating to possible control methods of the actuator in a calender according to the present invention;

[0033] · Figure 24 This schematically illustrates the axial misalignment of the two rollers. Detailed Implementation

[0034] The calender (1) according to the invention is a type of calender comprising a structural element formed by a support frame having a metal transverse member (10) and sidewalls (11H, 11K) defining spaces for housing two rolls (R1, R2), the two rolls being oriented such that their respective longitudinal axes are orthogonal to the same wall (11H, 11K), and the two rolls being positioned to define an indentation line (N) through which the material (W) to be processed can pass. The rolls (R1, R2) are heatable rolls and are removably supported by the structure (10, 11H, 11K) such that the heatable rolls can be removed and replaced with other heatable rolls when needed. The rolls (R1, R2) are designed to rotate at predetermined angular velocities in opposite directions about their respective longitudinal axes. For this purpose, as described above, a drive unit (UM) connected to the rolls (R1, R2) can be arranged to control the rotation of the rolls. For simplicity, only... Figure 4 The material (W) is shown by a horizontal dashed line, and the arrow above the dashed line indicates the direction the material itself follows.

[0035] Web-shaped materials (W) are a type commonly used in the manufacture of nonwoven products. For example, such materials can be composed entirely of thermoplastic fibers or of a mixture of thermoplastic and non-thermoplastic fibers, such as cellulose. These materials are used for processing by passing through a calender with heated rollers.

[0036] Each roll (R1, R2) includes an outer surface (100) having protrusions (RR) arranged according to a predetermined pattern. The rolls (R1, R2) are arranged in a so-called "tip-to-tip" configuration, meaning that the rolls are arranged such that the protrusion (RR) of one roll corresponds radially to the protrusion (RR) of the other roll. Furthermore, each roll (R1, R2) has a pin at each head (T1, T2): a first pin (101) and a second pin (102), wherein the first pin can be connected to a drive unit (UM), and the second pin allows the introduction of fluid for heating the roll. The pins (101, 102) are aligned along the longitudinal axis of the roll, which coincides with the roll's axis of rotation (rr) when the roll is positioned in the operating position described above. A calender with this configuration is described in WO2020 / 183504.

[0037] The following description is provided to illustrate possible embodiments of a calender equipped with a control mechanism according to the present invention. The control mechanism will be described below to better illustrate its operation. It should be understood that the structure of the calender, as well as the rolls and components connecting the rolls to the calender structure, the means for moving the rolls, and the method for heating the rolls, can be constructed in any other suitable manner besides those described below.

[0038] For example, the drive unit (UM) includes an electric motor (M) connected to two resilient axial joints (G1, G2) via a belt or chain drive (not visible in the figures) housed in a carter (CM) positioned outside the structures (10, 11H, 11K). Each joint (G1, G2) is arranged to correspond to the axis of rotation (rr) of the corresponding roller (R1, R2) and is equipped with a terminal end (200) that slides axially relative to the joint itself. An arm (201) is connected to the terminal (200) by insertion of a support (202). On the opposite side, the arm (201) is connected to a hydraulic actuator (203), which is integral with the sidewall (11K) of the structure. The terminal end (200) is shaped to engage with a power output (103) arranged on the end of a first pin (101) of the corresponding roller (R1, R2). According to the example shown in the attached drawings, the power output unit (103) is connected to the first pin (101) via a shrink ring (104). Since there are two engagements, equal to the number of rollers (R1, R2), two actuators (203) are provided, each acting on a corresponding arm (201), and each arm (201) is connected to the terminal end (200) of the corresponding engagement (G1, G2). Figure 18A In the middle, the joint (G1) is in the engaged position on the first pin (101), while Figure 18B The engagement portion is in the disengaged position. The engagement / disengagement position of the engagement portion on the first pin (101) is controlled by the actuator (203). Figure 18B As shown, in the disengaged position of the joint, a space (y) is formed between the terminal (200) and the power output portion (103) to allow the removal of the roller, as further described below.

[0039] According to the example shown in the accompanying drawings, the above structure includes a pair of sidewalls (11H, 11K) for each side, namely a pair of sidewalls (11H, 11K) on the drive unit (UM) side and a pair of sidewalls (11H, 11K) on the opposite side, thus having two outermost walls (11K) and two innermost walls (11H). The distance between the inner walls (11H) is less than the distance between the outer walls (11K). The inner sidewalls (11H) have two overlapping recesses (300) on their respective front portions (F), which are adapted to partially accommodate corresponding supports (105) formed by rollers (R1, R2) near their respective heads (T1, T2). Furthermore, an actuator (301), such as a hydraulic actuator, is mounted on the front portion (F) of each inner sidewall (11H), the stem portion (302) of which is constrained to the front end of a rod (303). The rod has a concave portion with its concave surface facing upwards and is hinged to a corresponding inner wall (11H) by a pin (340), the pin (340) having a horizontal axis arranged on the back side of the lower recess (300), i.e., on the back side of the base (BA) of the recess (300) closest to the structure. In practice, the pin (340) is located on the opposite side of the connection point (305) of the stem (302) at the front end of the rod (303). The concave portion of the rod (303) centered between the connection point (305) and the pin (340) mates with the corresponding lower recess (300), thereby defining the lower housing of the corresponding support (105) of the lower roller (R2). The actuators (301) are synchronized, causing the two rods (303) to rotate synchronously about their respective pins (340).

[0040] On each outer wall (11K), more precisely, on the side facing the corresponding inner wall (11H), a rod (304) is applied. The rod (304) preferably has a concave front portion (350) with its concave surface facing downwards. The rod (304) is constrained to the stem portion (306) of the corresponding hydraulic actuator (307), and the rod (304) is hinged to the wall (11K) by a pin having a horizontal axis (308) at an intermediate position between the concave front portion (350) of the rod and the point (309) for connection to the stem portion of the actuator (307). The front portion of each rod (304) is intended to engage from above with the support (106) presented by each roller (R1, R2), maintaining a predetermined distance from the aforementioned support (105). Above the first rod (304) is another rod (310), identical to the first rod (304), but positioned as a mirror image of the first rod (304), i.e., the concave portion of the corresponding front end (311) faces upwards instead of downwards. The additional rod (310) is also constrained to the stem (312) of the corresponding hydraulic actuator (313), and is hinged to the wall (11K) at an intermediate position between the front side (311) of the rod (310) and the connection point (315) to the actuator stem (313) via a corresponding pin (314) having a horizontal axis. The front side of the additional rod (310) is intended to engage the corresponding support (106) from below.

[0041] An additional rod (316) is mounted on the front side (F) of each inner wall (11H). The additional rod (316) is connected to the corresponding hydraulic actuator (317) on its rear side. The additional rod (316) has a concave portion (318) on its front side, which faces the rear (P) of the wall (11H) in the operating position of the calender. The additional rod (316) is hinged to the wall (11H) at an intermediate position between the front side (318) of the additional rod (316) and the connection point (320) with the stem of the actuator (317) by a corresponding pin (319) having a horizontal axis.

[0042] In practice, the following are applied to each outer sidewall (11K):

[0043] - A lower rod (304) controlled by an actuator (307) that controls the rotation of the lower rod (304) about a pin (308) having a horizontal axis, the same rod being connected to the wall (11K) via the pin (308), the free front end (350) of the lower rod (304) preferably being a concave portion with its concave side facing downwards; and

[0044] - An upper rod (310) controlled by an actuator (313) that controls the upper rod (310) to rotate about a horizontal axis pin (314), the same rod being connected to the wall (11K) through the horizontal axis pin (314), the free front end (311) of the upper rod (310) preferably being a concave portion with the concave surface facing upward.

[0045] Similarly, the following is applied to each inner sidewall (11H):

[0046] - A lower rod (303) controlled by an actuator (301) that controls the lower rod (303) to rotate about a horizontal axis pin (340), the same rod being connected to the wall (11H) through the horizontal axis pin (340), the middle portion of the lower rod (303) preferably being a concave portion with the concave surface facing upwards; and - an upper rod (316) controlled by an actuator (317) that controls the upper rod (316) to rotate about a pin (319) having a horizontal axis, the same rod being connected to the wall (11H) through the pin (319), the front portion (318) of the upper rod (316) preferably being a concave portion of the rear portion (P) facing the same wall (11H) when the calender is in the operating position.

[0047] Therefore, the calender described herein by way of example has two lower rods (303, 304) and two upper rods (316, 310) on each of its left and right sides. The two lower rods (303, 304) and the two upper rods (316, 310) are positioned at a predetermined distance (d) from each other and are adapted to contact corresponding supports (105, 106) arranged on the rolls (R1, R2), thereby applying forces (F1, F2, F3, F4) oriented according to non-coincident directions on the same support (105, 106). In practice, for each right or left side of the two rolls (R1, R2), the rods (303, 304, 310, 316) form two grippers that act along parallel planes spaced apart by a predetermined value (d).

[0048] Referring to the example in the accompanying drawings, the lower rods (303) and (308) apply an upward thrust (F1) to the support (105) adjacent to the head (T1, T2) of the lower roll (R2), and a downward thrust (F2) to the outermost support (106) of the same roll (R2). The upper rods (310) and (316) apply an upward thrust (F3) to the outer support (106) of the upper roll (R1) and a thrust (F4) towards the rear side (P) of the calender to the head (T1, T2) of the same upper roll (R1).

[0049] Therefore, the bending of the rollers (R1, R2) is reduced. In fact, the forces (F1, F2, F3, F4) act on parallel and non-coincident planes.

[0050] Referring to the example shown in the attached diagram, each roller (R1, R2) contains a conduit (HT) for feeding heating fluid, such as a type of through-heating oil commonly available on the market. For example, the type of through-heating oil shown in Table 1 below can be used, where the letters AE have the following meanings:

[0051] A: Manufacturer

[0052] B: Type

[0053] C: Viscosity at 40℃ (cSt or mm) 2 / s)

[0054] D: Viscosity at 100℃ (cSt or mm) 2 / s)

[0055] E: Density at 15℃ (Kg / m³) 3 )

[0056] F: Autoignition temperature (°C)

[0057] A B C D E F AGIP ALARIA 3 30 5.3 870 320 BP TRANSCAL N 30.4 5.28 870 350 ESSO ESSOTHERM 500 30 5.2 860 300 CHEM GROUP MARLOTHERM N 20 3.4 877 330

[0058] (Table 1)

[0059] For example, depending on the specific treatment to be performed on the material (W) introduced between the rolls (R1, R2) of the calender, the selected heat transfer oil is introduced into the pipe (HT) at a temperature between 170°C and 200°C.

[0060] The conduit (HT) is arranged along the longitudinal axis of the rolls (R1, R2) and has an inlet end (107) formed in a second pin (102) of the roll. The inlet end (107) of the conduit (HT) is provided with a valve (108) through which heating fluid can be introduced into the conduit (HT), and the valve also allows the inlet (107) to be blocked. The valve (108) is integral with the inlet (107) of the conduit (HT), and the conduit (HT) is integral with the rolls (R1, R2). In operation, the valve (108) is open to allow heating fluid to flow in the conduit (HT), and closed when the rolls (R1, R2) must be removed from the calender, as further explained below. Spacers (S1, S2) are arranged at predetermined distances from each head (T1, T2) such that corresponding chambers (C1, C2) are formed inside the rollers (R1, R2) and near each head (TR), wherein the first chamber (C1) is farther from the inlet (107) and the second chamber (C2) is closer to the inlet. A conduit (HT) terminates in the first chamber (C1), i.e., the outlet (109) of the conduit (HT) is located within the first chamber (C1). The first chamber has several holes (110) for communication with a heat exchanger (111), which is coaxial with and outside the conduit (HT). The second chamber (C2) also has more holes (110) for communication with the heat exchanger (111). A second conduit (RF) is arranged in the second pin (102) to form a return line for the heated fluid. The second conduit (RF) is coaxial with the first conduit (HT) and located outside the first conduit. The second conduit (RF) has an inlet portion (112) formed in a second head (T2) and an outlet portion (113) on which a corresponding valve (114) is mounted, allowing the heated fluid to exit through the portion (113) of the second conduit (RF) and also allowing that portion (113) to be blocked. The valve (113) is integrated with the outlet (113) of the conduit (RF), and the conduit (RF) is integrated with the rolls (R1, R2). In operation, the valve (113) is opened to allow the heated fluid to pass through the second conduit (RF), and the valve (113) is closed when the rolls (R1, R2) must be removed from the calender.

[0061] Therefore, heated fluid, introduced into the pipe (HT) at a predetermined pressure through the inlet (107), fills the first chamber (C1), flows through the heat exchanger (111), enters the second chamber (C2), and exits through the second pipe (RF). The inlet (107) of the delivery pipe (HT) and the outlet (113) of the return pipe (RF) are connected via respective valves (108, 114) to a fluid heating and supply system known per se, which only... Figure 22 The figure is labeled "HTS".

[0062] According to the example shown in the accompanying drawings, the delivery conduit (HT) and the heating fluid return conduit (RF) pass through the second pin (102), and valves (108, 114) are arranged from the same side on the free end of the second pin (102). Furthermore, the valves (108, 114) have respective outlets (180, 141) for insertion into conduits used for supplying and, correspondingly, discharging the heating fluid (not visible in the drawings).

[0063] The sheath (100) of the rollers (R1, R2) is coaxial with the heat exchanger (111) and located outside the heat exchanger (111). The sheath receives heat transferred by the heating fluid from the heat exchanger (111).

[0064] For example, the heat exchanger (111) inside the rollers (R1, R2) consists of a helical coil, the outer diameter of which corresponds to the inner diameter of the sheath (100) to ensure proper heat exchange. For example, the coil is formed from a tube with a rectangular cross-section wound in a helical manner. According to the described example, the exchanger (111) extends along the entire length of the rollers (R1, R2) between the two heads (T1, T2).

[0065] Preferably, a hydraulic coupling is installed at the end of the pin (102), which is formed by an internally hollow body (400) having a first internal axial conduit (401) and a second conduit (402). The end portion of the conduit (HT) is positioned in the first internal axial conduit (401), and the second conduit (402) is coaxial with the first conduit (401) and located outside the first conduit (401), forming an extension of the heated fluid return conduit (RF). The conduit (401) ends with a valve (108), while the conduit (402) ends with a valve (114). The body (400) of the coupling is integral with the rollers (R1, R2), and when the rollers are in the operating position, the body (400) of the coupling is locked to the corresponding wall (11K) of the calender (1) by a suitable accessory (403). In this way, the valves (108, 114) are always in the same position during the rotation of the rollers (R1, R2). In fact, the pin (102) rotates within the joint (400) where the valves (108, 114) are installed.

[0066] Preferably, the valves (108, 114) are applied to one side of the joint (400), which faces the rear side (P) of the calender (1) in the operating position of the rollers (R1, R2).

[0067] Valves (108, 114) are typically closed and opened by corresponding actuators (508, 514) installed at predetermined positions on the side wall (11K) of the calender (1). See also: Figure 14BThe example shown has two pairs of actuators (508, 514) on the sidewall (11K), namely one pair of actuators (508, 514) for each roller (R1, R2). See below for reference. Figure 19A and Figure 19B The diagram illustrates the operation of this part of the calender (1). Figure 19A and Figure 19B A single valve (108) is indicated, but it should be understood that the operation is the same for all valves, both the valve at the inlet (108) and the valve at the outlet (114) for the heating fluid: during the introduction of the heating fluid into the conduit (HT), the piston (581) of the actuator (508) pushes against the front base (181) of the valve (108), the movement of the front base (181) being transmitted to the lower element (182) of the inner assembly (182, 184) via a bridge (183) connecting the lower element (182) to the upper element (184), allowing the heating fluid to pass freely through the valve, as... Figure 19A The arrow "T" indicates the direction of movement; conversely, when valve (108) is closed, the piston of actuator (508) moves as follows: Figure 19B The retraction is as shown, such that the lower body (182) of the above-mentioned group (182, 184) is spaced apart from the upper body (184), and fluid cannot pass through the lower element (182) which is connected to the outlet (180), and fluid is prevented from escaping through the same outlet (180).

[0068] Such as especially Figure 22 and Figure 23 As shown, each pin (101, 102) can be provided with an internal channel designed to allow air to pass through, thereby reducing the pin's temperature and thus maintaining the integrity of the supports (105, 106). Therefore, control of the operating temperature of the supports (105, 106) can be achieved without providing an external cooling circuit typically found in hot rolling mills. Reference Figure 22 and Figure 23 In the example shown, a channel (CC) can be formed in each pin (101, 102), extending parallel to the axis of rotation (rr) of the roller. The channel (CC) forms a thermally insulating chamber within the pin, which insulates the support from the heat transferred by the heating fluid. Ultimately, air or even thermally insulating material may be present in the channel (CC). As shown, the channel (CC) extends below the support (105, 106).

[0069] The channel (CC) can also communicate with the outside through a first series of radial holes (RC) arranged near the opposite heads (T1, T2) and a second series of holes (SC) spaced a predetermined distance (a) from the first series of holes (RC). The pin diameters at the first series of radial holes (RC) are larger, and the pin diameters at the second series of holes (SC) are smaller. The axes of the second series of holes (SC) converge on the rotation axis (rr) of the roller, forming an inlet farther from the head and an outlet closer to the head. The distance (a) is greater than the distance between the supports (105, 106), so the air flowing in the channel (CC) can cool the two supports. Figure 24 As shown, in the pin (102) where the above-mentioned valves (108, 114) are installed, the passage (CC) is coaxial with the fluid return pipe (RF) and located outside the return pipe (RF).

[0070] External air enters the channel (CC) through the hole (SC) and exits through the radial hole (RC), resulting in adequate thermal insulation of the supports (105, 106) of the rollers (R1, R2). Figure 18C A nozzle (UR) is shown that blows air toward the orifice (SC) to further facilitate airflow through the conduit (CC) if needed.

[0071] The air cooling ducts are arranged in the two pins (101, 102) of the rollers (R1, R2), but the air cooling ducts can also be arranged only in pin (102). Figure 22 In the middle, the pin (101) is also equipped with the aforementioned cooling pipes.

[0072] Each pin (101, 102) of the rolls (R1, R2) may be fitted with two sleeves (B), each sleeve preferably being positioned in the middle between two corresponding supports (105, 106), and the sleeves being adapted to be engaged by the arm of a bridge crane (not shown) which functions to move the rolls (R1, R2) between the calender (1) and one or more stopping or waiting stations of the rolls.

[0073] For example, to allow the removal of rolls (R1, R2) from the calender (1), rods (303, 304, 310, 316) are manufactured to rotate around their respective pins via corresponding actuators (301, 307, 313, 317) to release supports (105, 106) and the rolls from the seat (300). At this stage, the rolls are disconnected from the drive unit, the corresponding power output (103) is released, and the supply of heating fluid is interrupted by closing valves (108, 114) via actuators (508, 514). The procedures involved in the removal process—disconnecting the rolls via a bridge crane, closing valves (108, 114), and releasing supports (105, 106)—are automatically managed by an actuator control unit (UE) that controls the actuators described above. Figure 23 The block diagram shows the control of the actuator by the actuator control unit (UE).

[0074] As previously described, the above description is provided to illustrate possible configurations of a calender that can be equipped with a control mechanism according to the invention. It should be understood that this mechanism is generally applicable to calenders constructed differently considering the following: support structure, rolls and components connecting the rolls to the calender structure, means for moving the rolls, and methods for heating the rolls themselves. Therefore, the control mechanism according to the invention can also be applied to calenders, particularly to heat treatment of web material passing through an embossing line formed by two thermally engraved rolls arranged end-to-end, wherein the structural support may consist of only two roll support walls, and the roll heating system may not be constructed as described above, but according to different standards, wherein the rolls are constrained to the support structure by constraint members other than the previously described rods (304, 310, 303, 316), and the rolls are driven to rotate about their respective longitudinal axes by motor components other than the previously described drive unit (UM). For example, as Figures 20A to 20C As shown, the drive unit (UM) includes two electric motors (M), one of which is used for one roll of the calender.

[0075] Advantageously, according to the invention, uniform heating of the rollers (R1, R2) is controlled to ensure the maintenance of the axial phase. Possible methods for implementing this control include detecting the axial elongation of the rollers (R1, R2) due to heating. Generally, according to the invention, unacceptable axial phase loss is associated with the different axial elongation rates of the two rollers exceeding a predetermined limit (e.g., 3 / 10 mm). For example, the detection can be performed using linear encoders (E1, E2) placed on one side of each roller (R1, R2) to measure the axial elongation due to heating of the rollers. Figure 22As schematically illustrated, each encoder (E1, E2) is connected to a programmable control unit (UCP), which receives electrical signals generated by the same encoder and compares them with each other. If the difference between the axial elongation of one roll and that of the other roll exceeds a predetermined threshold, the control unit (UCP) generates an alarm signal. This alarm signal can activate an audible and / or visual signaling device (SAL) and / or a program to automatically restore the calender to normal operating condition.

[0076] Sound and / or light signals can be used to alert the operators responsible for manipulating the calender, thereby enabling them to intervene and restore the calender to normal operation by manually adjusting the amount of hot fluid introduced into the rolls so that the difference in axial elongation between the rolls (R1, R2) is below a preset threshold.

[0077] The procedure for automatically restoring the calender to normal operation includes automatically adjusting the amount of hot fluid introduced into the rolls. In this case, for example, a control unit (UCP) is connected to a valve (108) located at the inlet (107) for introducing hot fluid into the rolls (R1, R2), the valve (108) being a solenoid valve controllable by the control unit (UCP). By controlling the closing and opening of the solenoid valve (108), the control unit (UCP) can adjust the operating temperature of each roll (R1, R2) so that the difference in the axial elongation of the rolls themselves is below a preset threshold. The sign of the difference in axial length thus detected can be used to identify the hotter roll. For example, if the difference in elongation (dL1, dL2) of the rolls (R1, R2) D = dL1 - dL2 is positive, the control system interprets this as the roll (R1) having a larger axial elongation than the roll (R2). Conversely, if the difference in elongations (dL1, dL2) between the rollers (R1, R2) is negative, D = dL1 - dL2, the control system interprets this as roller (R2) having a larger axial elongation than roller (R1). Therefore, if the difference in axial elongation exceeds a predetermined threshold, the control unit (UCP) reduces the flow rate of the heating fluid introduced into the hotter roller. Figure 24 This represents an operating condition where, for example, the upper roll (R1) experiences a greater elongation than the lower roll (R2), making the difference D = dL1 - dL2 positive. In a magnified detail of the same figure, it can be seen that the greater axial elongation of roll (R1) has determined that the convexities (RR) of the two rolls have lost their correspondence, particularly on one side of the calender (the right side of the figure).

[0078] Alternatively, if the difference in axial elongation exceeds a preset threshold, the control unit (UCP) modifies the setpoint of the heating unit of the hotter roller. In this case, the control unit (UCP) does not intervene with the valve (108), but instead commands the setpoint for supplying fluid to the heating unit of the hotter roller to be lowered. Figure 22 In the diagram, the connection between the control unit (UCP) and the heating unit (HTS) is indicated by a dashed arrow "UH". The previously described association with the sign of the difference between the axial elongation rates of the rollers (R1, R2) also applies to this case.

[0079] In both of the above cases, the system for heating the rolls (R1, R2) includes several individually controllable heating units (HTS), each of which feeds hot fluid into its respective calender roll.

[0080] In practice, the axial elongation of the rolls (R1, R2) is controlled by active control of the operating temperature of the rolls themselves. This active control is performed by detectors (e.g., the encoders E1, E2) configured to detect the axial elongation of the rolls and connected to a control unit (UCP). The control unit is configured to adjust the operating temperature of the rolls based on the detection performed by the detectors to keep possible differences in the axial elongation of the rolls below a predetermined threshold.

[0081] refer to Figures 18A to 18C In the example structure shown, each encoder (E1, E2) is a magnetic encoder mounted on an arm (201) of an engagement / disengagement mechanism that drives the motion of the rollers (R1, R2). In this example, each encoder (E1, E2) includes a magnetic slider (MS) fixed to a plate (PM), which in turn is fixed to one side of the corresponding arm (201). Therefore, each translation of the arm (201) parallel to the axis (rr) of its respective roller (R1, R2) involves an equal translation of the magnetic slider (MS) on the corresponding encoder, thus generating a position signal related to the position of the arm (201). Figure 18C The arrow "SA" in the middle Figure 18A The enlarged detail diagram shows the thrust applied to the arm (201) by the extension of the roller (R1), which corresponds to the translation of the slider (MS) of the encoder (E1) visible in the diagram.

[0082] The axial elongation (elongation along the rr axis) of any calender roll implies a thrust exerted by that roll on its respective support (202), which determines the translation of the corresponding arm (201) parallel to the roll's axis (rr), and thus the translation of the magnetic slider (MS) converted into a position signal by an encoder, which is transmitted to the control unit (UCP), programmed to intervene as described above. Since the actuator (203) is a pneumatic or hydraulic actuator operating at relatively low pressure, it does not impede the roll's elongation, and therefore does not impede the translation of the arm (201), nor does it impede the translation of the magnetic slider (MS).

[0083] according to Figure 21 In the example shown, there is an attachment (211) on the bracket (210) used to connect the actuator (203) to the wall (11K) of the calender, and an inductive sensor (IS) is mounted on the attachment (211). The inductive sensor (IS) detects the distance between the arm (201) and the attachment (211). Therefore, similar to the case in the previous example, each translation of the arm (201) parallel to the axis (rr) of the relevant rollers (R1, R2) involves an equal translation of the arm (201) detected by the inductive sensor (IS). Figure 21 The arrow “SA” in the diagram also indicates the thrust exerted on the arm (201) by the extension of the roll (R1). In this example, an inductive sensor (IS) is provided for each calender roll. Furthermore, also in this case, the sensor (IS) constitutes a transducer that generates a position signal of the arm (201) used by the control unit (UCP) as described above.

[0084] In practice, according to the present invention, it is conceivable to detect the axial elongation of each roll of a calender by means of sensors constructed for this purpose and arranged in the calender to detect the axial elongation caused by heating of the same roll, and to compare the elongation of the roll by a programmable control unit, and to generate an alarm signal if the difference between these elongation rates exceeds a predetermined limit.

[0085] The actuator control unit (EU) and the control unit (UCP) can be physically integrated.

[0086] According to the above description, the calender according to the invention is a calender for processing web material (W), the calender comprising a fixed structure (10, 11H, 11K, 300) adapted to support two mutually heated rollers (R1, R2), the rollers being arranged to form an imprint line (N) through which the web material (W) can pass, wherein each roller (R1, R2) has surface protrusions (RR) arranged according to a predetermined pattern, wherein the rollers (R1, R2) are arranged end-to-end with each other, such that in the operating position of the calender, the protrusions (RR) of one roller (R1) and the protrusions (RR) of the other roller (R2) are radially opposite each other corresponding to the imprint line (N), wherein each roller (R1, R2) is connected to a drive unit (UM), the drive unit (UM) determining the... Each of the rollers rotates about its own longitudinal axis (rr) at a predetermined angular velocity, wherein the rollers (R1, R2) are heated by heating elements configured to heat each roller (R1, R2) of the calender respectively, and wherein each roller (R1, R2) undergoes axial elongation due to heating by the heating elements, and the calender includes: detection devices (E1, E2; IS) adapted to detect the axial elongation rate of each roller (R1, R2); and a programmable control unit (UCP) connected to the detection devices and the heating devices, the programmable control unit being programmed to: determine the difference between the axial elongation rates of the rollers (R1, R2) detected by the detection devices, and issue an alarm signal if the absolute value of the difference is greater than a predetermined limit value.

[0087] According to a specific implementation method of the present invention, the calender according to the present invention may have one or more of the following features:

[0088] The detection device consists of magnetic encoders (E1, E2).

[0089] - The encoders (E1, E2) are linear encoders.

[0090] - The detection device consists of an inductive sensor (IS).

[0091] - The detection device is arranged at one end of the rollers (R1, R2) and operates at that end.

[0092] - The alarm signal controls the activation of sound and / or light signals.

[0093] The alarm signal controls the heating devices (R1, R2) of the roller by reducing the temperature of the roller subjected to a large elongation, and the control unit (UCP) determines whether the difference is positive or negative.

[0094] Rollers (R1, R2) are rotated about their respective longitudinal axes by a drive unit (UM), which includes one or two electric motors (M).

[0095] - The rollers (R1, R2) are provided with internal conduits (HT, RF) in which the fluid fed by the heating device can flow.

[0096] A method for processing web-shaped material (W) using a calender, the calender comprising a fixed structure (10, 11H, 11K, 300) adapted to support two mutually heated rollers (R1, R2), the rollers being arranged to form an imprint line (N) through which the web-shaped material (W) can pass, wherein each roller (R1, R2) has surface protrusions (RR) arranged according to a predetermined pattern, wherein the rollers (R1, R2) are arranged relative to each other in a tip-to-tip configuration such that, in the operating position of the calender, the protrusions (RR) of one roller (R1) and the protrusions (RR) of the other roller (R2) are radially opposite each other corresponding to the imprint line (N), wherein each of the rollers (R1, R2) is connected to a drive unit (UM) for driving. The unit (UM) determines the rotation of each of the rollers about its own longitudinal axis (rr) at a predetermined angular velocity, wherein the rollers (R1, R2) are heated by heating elements configured to heat each roller (R1, R2) of the calender respectively, and wherein each roller (R1, R2) undergoes axial elongation due to heating by the heating elements. The method according to the invention involves: detecting the axial elongation rate of each roller (R1, R2) using devices (E1, E2; IS) for detecting the axial elongation rate of the rollers (R1, R2); determining the difference between the axial elongation rates of the rollers (R1, R2) detected by the detection devices (E1, E2; IS), and issuing an alarm signal if the absolute value of the difference is greater than a predetermined limit value.

[0097] According to a specific method for implementing the method of the present invention:

[0098] - The axial elongation of the rollers (R1, R2) is detected by a detection device including a magnetic encoder (E1, E2) or an inductive sensor (IS).

[0099] - When using magnetic encoders, these encoders (E1, E2) are preferably linear encoders.

[0100] - The detection device is preferably arranged on one end of the rollers (R1, R2) and operates at that end.

[0101] - The alarm signal controls the activation of sound and / or light signals.

[0102] The alarm signal is issued by a control unit (UCP), which controls the roller heating devices (R1, R2) by reducing the temperature of the rollers subjected to a large elongation. The control unit (UCP) evaluates whether the sign of the difference is positive or negative based on the detection performed by the detection device.

[0103] In practice, the implementation details can vary in any case according to the various elements described and illustrated and their arrangement with each other, without deviating from the idea of ​​the solution adopted, and thus remain within the scope of protection conferred by this patent under the appended claims.

Claims

1. A calender for processing web material (W), the calender comprising a fixed structure (10, 11H, 11K, 300) adapted to support two heated rollers (R1, R2) arranged relative to each other to form an imprint line (N) through which the web material (W) can pass, wherein, Each roll (R1, R2) has surface protrusions (RR) arranged according to a predetermined pattern, wherein the rolls (R1, R2) are arranged end-to-end in such a configuration that, in the operating settings of the calender, the surface protrusions (RR) of one roll (R1, R2) are radially opposite to the surface protrusions (RR) of the other roll corresponding to the indentation line (N), wherein each roll (R1, R2) is connected to a drive unit (UM) that determines the rotation of each roll about its own longitudinal axis (rr) at a predetermined angular velocity, wherein the rolls (R1, R2) are heated by a heating device configured to heat each roll (R1, R2) of the calender respectively, and wherein each roll (R1, R2) is... The calender, subjected to axial elongation by heating by the heating device, is characterized in that the calender comprises: a detection device (E1, E2; IS) adapted to detect the axial elongation rate of each roll (R1, R2); and a programmable control unit (UCP) connected to the detection device and the heating device, the programmable control unit being programmed to: determine the difference between the axial elongation rates of the rolls (R1, R2) detected by the detection device and to determine the positive or negative sign of the difference; and the programmable control unit to issue an alarm signal if the absolute value of the difference is greater than a predetermined limit value, and to control the heating device of the roll (R1, R2) subjected to a larger elongation rate by reducing the temperature of the roll.

2. The calender according to claim 1, characterized in that, The detection device is a magnetic encoder (E1, E2).

3. The calender according to claim 2, characterized in that, The magnetic encoders (E1, E2) are linear encoders.

4. The calender according to claim 1, characterized in that, The detection device is an inductive sensor (IS).

5. The calender according to any one of claims 1 to 4, characterized in that, The detection device is arranged at one end of the rollers (R1, R2) and operates at that end of the rollers (R1, R2).

6. The calender according to any one of claims 1 to 4, characterized in that, The alarm signal controls the activation of sound and / or light signals.

7. The calender according to claim 1, characterized in that, The rollers (R1, R2) are rotated around their respective longitudinal axes by a drive unit (UM), which includes one or two electric motors (M).

8. The calender according to claim 1, characterized in that, Both rollers (R1, R2) are provided with internal pipes (HT, RF), through which fluid fed by the heating device can flow.

9. A method for processing a web material (W) using a calender, said calender comprising a fixed structure (10, 11H, 11K, 300) adapted to support two heated rollers (R1, R2) arranged relative to each other to form an imprint line (N) through which the web material (W) can pass, wherein, Each roll (R1, R2) has surface protrusions (RR) arranged according to a predetermined pattern, wherein the rolls (R1, R2) are arranged end-to-end in such a configuration that, in the operating settings of the calender, the surface protrusions (RR) of one roll (R1, R2) are radially opposite to the surface protrusions (RR) of the other roll (R1, R2) corresponding to the embossed line (N), wherein each roll (R1, R2) is connected to a drive unit (UM) that determines the rotation of each roll about its own longitudinal axis (rr) at a predetermined angular velocity, wherein the rolls (R1, R2) are heated by a heating device configured to heat each roll (R1, R2) of the calender respectively. The method involves heating rollers (R1, R2) and wherein each roller undergoes axial elongation due to heating by the heating device, characterized in that the method includes detecting the axial elongation rate of each roller (R1, R2) using detection devices (E1, E2; IS) adapted to detect the axial elongation rate of each roller (R1, R2); and the method includes determining the difference between the axial elongation rates of the rollers (R1, R2) detected by the detection device and determining the positive or negative sign of the difference, generating an alarm signal if the absolute value of the difference is greater than a predetermined limit value, and controlling the heating device used to heat the roller (R1, R2) by reducing the temperature of the roller (R1, R2) undergoing a larger elongation rate.

10. The method according to claim 9, characterized in that, The axial elongation of the rollers (R1, R2) is detected by a detection device including a magnetic encoder (E1, E2) or an inductive sensor (IS).

11. The method according to claim 9, characterized in that, The detection device is arranged at one end of the rollers (R1, R2) and operates at that end of the rollers (R1, R2).

12. The method according to claim 9, characterized in that, The alarm signal controls the activation of sound and / or light signals.

13. The method according to claim 9, characterized in that, The alarm signal is issued by the control unit (UCP), which controls the heating device used to heat the rollers (R1, R2) by reducing the temperature of the rollers subjected to a large elongation. The control unit (UCP) determines the positive or negative sign of the difference based on the detection performed by the detection device.

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