SE538040C2 - Shoe press and machine for making laminated cardboard - Google Patents

Abstract

The invention relates to a shoe press 3 which comprises a rotatably mounted counter roller 4, a bar beam 5, an elongate pressure shoe 6 with an upstream 7 and a downstream 8 and a concave surface 9 water against the counter roller 4. The pressure shoe 6 has a metal core 10 and a layer 11 of resilient material on the concave surface 9. The pressure shoe 6 is supported by the bar beam 5 and the pressure shoe 6 also has a lubrication pocket 12 formed in the layer 11 of resilient material and at least one channel 13 for a lubricant leading to the lubrication pocket 12 so that the lubrication pocket 12 can be supplied with a lubricant. The lubrication pocket 12 is closer to the upstream sand 7 than the downstream sand 8 of the pressure shoe 6. The shoe press further comprises devices 14 for pressing the pressure shoe 6 against the counter roller 4 to form a nip with the counter roller 4 so that pressure, in the pinch, is distributed along the length of the pinch. A flexible tubular jacket 15 runs in a loop around the pressure shoe 6 and the bar beam 5 and the flexible tubular jacket 15 is rotatable so that the flexible tubular jacket 15, upon its rotation, passes through the nip and separates the pressure shoe 6 from the counter roller 4. The shoe press 3 further comprises a trough 16 which is supported by the bar beam 5 and is placed at the upstream sand 7 of the pressure shoe 6 so that it can receive lubricant which is ironed off from the flexible tubular jacket 15 at the beginning of the nip. The pressure shoe 6 and the devices 14 for pressing the pressure shoe 6 against the counter-roller 4 are arranged so that the pressure in the nip reaches its highest value at a point which is closer to the upstream sand 7 than the downstream sand 8 of the pressure shoe 6. The invention also relates to a machine using the shoe press according to the invention.

Description

FIELD OF THE INVENTION The present invention relates to a shoe press and a machine for producing laminated cardboard.

BACKGROUND OF THE INVENTION It is previously known to produce laminated board in a process where an applicator is used to apply a polymeric material to a web and then the web and the applied polymer web are then passed through a press in which a nip can be formed between two rollers. Examples of this technology are shown in, for example, U.S. Pat. 7922945. U.S. Pat. 6821373 and U.S. Pat. 8409679. One type of nip that can be used for this purpose is an obsolete nip such as the nip formed in a shoe press.

Shoe presses are known from the prior art and have been described in, for example, U.S. Pat. 7635419, U.S. Patent No. 7387710, U.S. Pat. 6517683, U.S. Pat. 6383338. U.S. Pat. 6355143, U.S. Pat. U.S. Patent No. 5,951,824 and U.S. Pat. 5662777.

In a shoe press nip, the pressure is distributed along the length of the nip according to a sample so that it can be displayed graphically with a curve. This curve is often called a "pressure profile". Shoe presses were originally developed for pressing wet fiber webs during the papermaking process, i.e. for drainage. When shoe presses are used for this purpose, the pressure profile is often shifted towards the end of the nip so that the pressure reaches its maximum just before the end of the nip in the stable at the middle of the nip. The reason for this is that such a pressure profile has been found to lead to less recovery, as explained in, for example, U.S. Pat. 6248210.

When a shoe press is used for other purposes than dewatering, recycling is not a problem and the pressure profile can take a different form. An object of the present invention is to provide a shoe press which is suitable for use in connection with the manufacture of laminated products. SUMMARY OF THE INVENTION The invention relates to a shoe press comprising a rotatably mounted counter roller, a bar beam and an elongate pressure shoe with an upstream and a downstream and a concave surface of water against the counter roller. The pressure shoe has a metal core and a layer of resilient material on the concave surface and the pressure shoe is supported by the bar beam.

The pressure shoe has a lubricating pocket formed in the resilient material and at least one channel for a lubricant leading to the lubricating pocket so that the lubricating pocket can be supplied with a lubricant. The lubrication pocket is closer to the upstream sand than the downstream sand of the pressure shoe. The shoe press further comprises means for pressing the pressure shoe against the counter-roller to form a nip with the counter-roller so that pressure, in the nip, is distributed along the length of the nip. The shoe press also comprises a flexible rudder-shaped jacket which runs in a loop around the pressure shoe and the bar beam and the flexible rudder-shaped jacket is rotatable so that the flexible rudder-shaped jacket, upon its rotation, passes through the nip and separates the pressure shoe from the counter roller. The shoe press also comprises a hopper which is carried up by the bar beam and is placed at the upstream sand of the pressure shoe so that it can receive lubricant which is ironed off from the flexible tubular jacket at the beginning of the nip. The pressure shoe and the devices for pressing the pressure shoe against the counter-roller arranged so that the pressure in the nip reaches its highest value at a point which is closer to the upstream sand than the downstream sand of the pressure shoe.

In advantageous embodiments, the length of the nip in the machine direction is in the range 40 mm - 120 mm and the lubrication pocket is located within the first 40 percent of the length of the nip and the pressure in the nip reaches its highest value within the first 40 percent of the length of the nip. However, you can also think of other numerical values.

In advantageous embodiments of the invention, the layer of resilient material has a thickness in the range 20 mm - 30 mm. However, you can also think of other thickness guards.

In advantageous embodiments of the invention, the resilient material is polyurethane or a material comprising polyurethane and the resilient material is bonded to the metal core. However, it is also possible to refuel with other materials other than polyurethane and liner molds are tankable where the layer of resilient material is not bonded to the metal core.

The lubrication pocket has an extension in the machine direction which is in the range 3 mm - 9 mm, preferably 4 mm - 8 mm. 2 538 0 The pocket is designed to gradually become shallower against the downstream sand of the pocket.

The lubrication pocket is divided in the direction transverse to the machine in a plurality of separate compartments separated from each other in the direction transverse to the machine by cradles formed in the resilient material.

In advantageous embodiments, the bar beam has a pin at each axial end of the bar beam and the devices for pressing the shoe against the counter-roller are devices which are arranged to act on the pins of the support beam.

In many realistic embodiments, the pressure shoe has a width in the direction across the machine which is in the range 1200 mm - 2500 mm, preferably in the range 1400 mm - 10 2000 mm.

The invention also relates to a machine for producing a laminated packaging material, which machine comprises an applicator for applying a polymeric material to a web and, following the applicator, a shoe press for compressing the web and the polymeric material and which shoe press is a shoe press as described above.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a machine for producing a laminated material, in particular a laminated packaging material.

Figure 2 is a cross-sectional view of a shoe press according to the invention.

Figure 3 shows the shoe's pressure profile in the nip. Figure 4 is a cross-sectional view of the shoe.

Figure 5 shows a detail of the shoe according to Figure 4. Figure 6 is a top view of the surface of the shoe.

Figure 7 is a front view of the shoe roller used in the shoe press according to the invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, a machine 19 for making a laminated packaging material is shown. The machine 19 comprises a first roll 2 from which a web W can be unwound and fed to a press 3. The web W can be, for example, a fiber web W as a cardboard web. The web W may, for example, be a fibrous web W as well as a cardboard web. The web W may be a web which has not been laminated before, but may also be a web W which has already been laminated on the flakes of both its sides or on the back sides. Before the web W arrives at the press 3, an applicator 1 is used to apply a layer of another material to the web W. The layer applied by the applicator 1 may be, for example, a layer of plastic film. The applicator 1 can be of any bachelor type. Examples of such devices are shown in, for example, U.S. Pat. U.S. Patent No. 4,405,400; 6821373 and U.S. Pat. 8409679. The web W and the layer applied by the applicator 1 are compressed into a laminated web in the press 3. After the press 3, the laminated product can be fed to a second roll 20.

The press 3 can, in principle, be any kind of press formed by two rollers which form a nip between them. However, the present invention is intended for use in the case where the press 3 is a shoe press formed by a shoe roll 21 and a rotatably mounted counter roll 4.

Practical experience has shown that a shoe press is advantageous for the manufacture of laminated products, since the nip provided by a shoe press is longer than a nip formed between two ordinary rollers. The longer new plan (the new plan is determined by the shoe) results in a process in which the web W and the layer applied can be compressed for a longer time. This gives an overall result.

Referring to Figure 2 and Figure 4, the shoe roller 21 includes a bead beam 5 and an elongate pressure shoe 6 with an upstream 7 and a downstream 8. As shown in Figure 4, the pressure shoe 6 has a concave surface 9 water against the counter roller 4. The pressure shoe 6 has in addition a metal core and a layer 11 of resilient material on the concave surface 9. The pressure shoe 6 is supported by the bar beam 5 and the pressure shoe 6 has a lubrication pocket 12 formed in the layer 11 of resilient material and at least one channel 13 for a lubricant leading to the lubrication pocket 12 said that the lubrication pocket 12 can be supplied with a lubricant. As shown in Figure 4, a transverse inlet duct 22 may be formed in the metal core and extend in one direction across the machine so that the lubrication pocket 12 may be supplied via more than one duct 13. Several ducts 13 for a lubricating fluid such as oil may be distributed along the pressure shoe 6. in the CD direction across the machine. It should be noted that the lubrication pocket 12 is closer to the upstream sand 7 than the downstream sand 8 of the pressure shoe 6. The shoe roll 21 also comprises devices 14 for pressing the pressure shoe 6 against the counter roller 4 to form a nip N with the counter roller 4 so that pressure, in the pinch N , distributed along the length of the nip N. In the embodiment shown in Figure 4, the devices 14 for pressing the pressure shoe 6 against the counter roller can be formed by one or two rows of hydraulic cylinders carried by the bar beam 5 and acting on the pressure shoe 2. It should be understood, however, that the devices 14 for pressing the pressure shoe 6 against the counter-roller 4 can take many different forms, for example as shown in U.S. Pat. The devices 14 for pressing the pressure shoe 6 against the counter roller 4 can be designed so that they can generate a pressure profile which is offset towards the beginning of the nip N. This can be achieved, for example, if the devices 14 for pressing the pressure shoe 6 against the counter roller assume the shape of two rows of actuators (eg hydraulic cylinders) which can be loaded separately as shown in, for example, U.S. Pat. No. 4,713,147 or U.S. Pat. 4917768. However, many others are set to provide a staggered pressure profile also known, see for example U.S. Pat. 7172679.

The shoe roller 21 also comprises a flexible rudder-shaped jacket 15 which runs in a loop around the pressure shoe 6 and the bar beam 5 and which flexible rudder-shaped jacket 15 is rotatable so that the flexible rudder-shaped jacket 15, during its rotation, passes through the nip and separates the pressure shoe 6 from the counter roller 4 The flexible tubular jacket may be made of polyurethane or a material comprising polyurethane, but other materials may also be considered. An example of a flexible tubular jacket that could be used in the present invention is shown in, for example, U.S. Pat. 6214752. Another example of a flexible tubular sheath that could be used in the present invention is shown in U.S. Pat. 8568567. The shoe press 3 further comprises a trough 16 which is supported by the bar beam 5 and is placed at the upstream sand 7 of the pressure shoe 6 so that it can receive lubricant which is ironed off from the flexible tubular jacket 15 at the beginning of the nip N. That is to say the trough 16 was supported by the bar beam 5 either directly or indirectly via the pressure shoe 6 which was also supported by the bar beam. The position of the trough 16 can be seen as defining the upstream sand 7 of the pressure shoe 6, since the trough is located at the upstream sand 7 of the pressure shoe 6. According to the invention, the pressure shoe 6 and the devices 14 for pressing the pressure shoe 6 against the roller 4 are arranged so that the pressure in the nip N At its point closer to the upstream sand 7 than the downstream sand 8 of the pressure shoe 6. In preferred embodiments of the invention, the highest pressure in the nip N coincides with the lubrication pocket 12. Lubricating fluid (e.g. lubricating oil) which is wiped off from the flexible tubular the jacket 15 and received by the hopper 16 can be emptied from the hopper 16 by means of a pipeline 23 connected to the hopper 16.

It has been found that when a shoe press is used for the manufacture of laminated products, so. the best effect is obtained when the pressure profile is displaced towards the beginning of the nip N so that the pressure reaches its highest level at a point in the nip N which is close to the beginning of the nip, i.e. near the upstream sand of the pinch. With a slender pressure profile, the web W and the applied layer of another material will be effectively bonded together.

If the pressure reaches its highest level already at the beginning of the nip N, there is a risk that lubricating oil which has been supplied to the inner surface of the flexible tubular belt will be chlorinated to such an extent that lubrication will not work properly in the nip N and the flexible tubular jacket 15 can be damaged. To prevent this Milder being a lubrication pocket arranged at the beginning of the nip N, extra lubricating fluid is supplied to the part of the nip N where the risk of insufficient lubrication is greatest.

Referring to Figure 3, the pressure in the nip N preferably exceeds its peak value at a point coinciding with the lubrication pocket 12 and this point is marked with "LP" in Figure 3.

In advantageous embodiments, the length of the nip N in the machine direction MD is in the range 40 mm - 120 mm or 50 mm - 110 mm. The length of the nip N can be, for example, 50 mm, 60 mm or 100 mm. However, you can refuel with new plans that are smaller than 40 mm or stone 120 mm. The nip N may, for example, have a length of 150 mm or 35 mm. The lubrication pocket 12 is preferably located within the first 40 percent of the length of the nip N and the pressure in the nip N reaches its highest value within the first 40 percent of the length of the nip N. The pressure should preferably reach its highest value at a point which, shaved from upstream sand of the nip N, is within 10% - 25% of the distance from the beginning of the nip (for example: if the total new plane is 100 mm, the pressure should preferably reach its highest value at a point somewhere within the range 10 mm - 25 mm from the beginning of the rosehip N).

The layer 11 of resilient material has a thickness Mom range 20 mm - 30 mm. Below the layer 11 of resilient material there is a metal core which is much stiffer than the layer 11 of resilient material. In theory, the entire pressure shoe 6 could be made of a resilient material such as polyurethane. In connection with water pressing of paper webs, the entire printing shoe can sometimes be made of a resilient material. In connection with the production of laminated products, however, the total thickness of the web W and the layer applied together can often vary and experience has shown that a pressure shoe 6 which is too soft is incapable of adapting quickly to new operating conditions. For this reason, there should be a rigid metal core and the layer 11 of resilient material should not be too thin. In an embodiment which the inventor envisages, the layer 11 of resilient material may have a thickness of 25 mm, or about 25 mm. In theory it could also be possible to use a printing shoe 6 where the whole shoe is made of a relatively rigid material such as metal. for example st5.1. However, when the printing shoe 6 is to be used for the production of laminated products, splicing of different webs can often be necessary during the process. When splicing, the pressure shoe 6 should not be rigid, the Mr should be compliant in any man.

In three embodiments of the invention, the resilient material is polyurethane or a material comprising polyurethane and the layer 11 of resilient material may preferably (but need not necessarily) be bonded to the metal core 10.

The lubrication pocket 12 preferably has an extension in the machine direction MD which is within the range 3 mm - 9 mm, preferably 4 mm - 8 mm.

In preferred embodiments, the lubrication pocket 12 is designed to be gradually shallower against the downstream edge of the lubrication pocket 12. As shown in Figure 5, the lubrication pocket 12 becomes gradually shallower in the machine direction MD, i.e. in the direction of the end of the nip N.

As shown in Figure 6, the lubrication pocket 12 may be divided in the direction CD across the machine into a plurality of separate compartments 12a, 12b, 12c, 12d, 12e spaced apart in the direction across the machine (CD) of cradles 17 formed in the layer 11. of resilient material. Each of these compartments 12a, 12b, 12c, 12d, 12e can be supplied with a lubricant via a separate lubricant channel 13. Figure 6 shows 5 separate compartments 12a, 12b, 12c, 12d, 12e, but it should be understood that it can there are more than four such compartments, or fewer than four compartments. For example, there could be 6 - 25 such compartments, or 2-4 such compartments. It should also be understood that the lubrication pocket 12 may be only a single pocket without partitions 17.

Reference will now be made to Figure 7. In preferred embodiments of the invention, the devices 14 for pressing the pressure shoe 6 against the counter roller 4 are not arranged on the bar beam 5, as is usual in connection with water pressing in paper machines. In the embodiment according to Figure 7, the bar beam 5 has a pin 18 at each axial end of the bar beam 5 and the devices 14 for pressing the pressure shoe 6 against the counter roller 4 there are devices which are arranged to act on the pins 18 of the bar beam 5. The devices 7 538 0 14 for pressing of the pressure shoe 6 against the counter roller 4 may be, for example, hydraulic or pneumatic cylinders acting on the pins 18. In such embodiments, the pressure shoe 6 may be arranged eccentrically in relation to the press plane to obtain a pressure profile which is offset from a spirit of the nip N. solution is shown in, for example, U.S. Pat. 4931142. In U.S. Pat. 4931142, the pressure shoe is eccentrically placed to achieve a pressure maximum towards the end of the press nip, but the same principle can be used to achieve a pressure profile which is offset towards the beginning of the nip N.

The shoe roller 21 can advantageously (but not necessarily) be connected to a Ulla for compressed air so that the interior of the shoe roller 21 can be filled with compressed air. In this case, the flexible tubular jacket 15 can be inflated like a balloon by the compressed air. This can make it easier for the flexible tubular jacket 15 to retain its shape during operation.

The vane roller 21 may advantageously (but does not necessarily need) have end clamping rings for fixing the axial edges of the flexible tubular jacket to rotatable ends. Examples of such an arrangement are shown in, for example, U.S. Pat. 6782811 and U.S. Pat. 6010443.

The counter roll 4 may optionally have a coating, for example a ceramic coating, or it may (optionally) have a roll coating of a flexible material. It can optionally be a heatable roller.

On the pressure shoe 6, the surface 9 facing the counter roller may optionally have a shape which is non-concave when the pressure shoe 6 is not pressed against the counter roller. The surface 9 facing the counter-roller 4 may, for example, be flat when the pressure shoe is not pressed against the counter-roller 4. This may be the case when the layer 11 of resilient material is so thick and resilient that the pressure shoe 6 can be deformed into a concave shape when pressed against the counter-roller. However, the surface 9 of the printing shoe 6 preferably has a concave shape already in the unloaded state of the shoe press.

The surface 9 is thus the surface facing the counter roller 4 and this surface 9 is preferably concave in the unloaded state of the shoe press, but may optionally be non-concave.

The pressure shoe 6 can have a width in the direction transverse to the machine which lies Mom range 1200 mm - 2500 mm, preferably Mom range 1400 mm - 2000 mm.

The shoe press according to the invention is, in particular with regard to the pressure curve, primarily intended for use in connection with the production of a laminated packaging material. However, uses for other purposes can be considered, such as water pressing or calendering, depending on the requirements in each individual case. Although the invention has been described above mainly in the form of a shoe press, it should be understood that the invention may also be defined in the form of a machine 19 for producing a laminated packaging material, which machine comprises an applicator for applying a polymeric material to a and, following the applicator, a shoe press 3 for compressing the web and the polymeric material, and wherein the shoe press 3 is the shoe press according to the invention described above. 9

Claims (10)

538 0 PATENT REQUIREMENTS Shoe press (3), comprising a rotatably mounted counter roller (4), a bar beam (5), an elongate pressure shoe (6) with an upstream (7) and a downstream (8) and a concave surface (9) of water against the counter roller (4), wherein the pressure shoe (6) has a metal core (10) and a layer (11) of resilient material on the concave surface (9) and wherein the pressure shoe (6) is supported by the bar beam (5) and wherein the pressure shoe (6) has a lubricating pocket (12) formed in the layer (11) of resilient material and at least one channel (13) for a lubricant leading to the lubricating pocket (12) so that the lubricating pocket (12) can be provided with a lubricant, the lubricating pocket (12) being is closer to the upstream sand (7) than the downstream sand (8) of the pressure shoe (6), devices (14) for pressing the pressure shoe (6) against the counter roller (4) to form a nip with the counter roller (4) so that pressure, in the nip, distributed along the length of the nip, a flexible rudder-shaped sheath (15) running in a loop around the pressure shoe (6) and the bar beam (5) and which flexible rudder-shaped sheath ( 15) is rotatable so that the flexible tubular jacket (15), upon its rotation, passes through the nip and separates the pressure shoe (6) from the counter roller (4), characterized in that the shoe press (3) also comprises a tag (16) which is supported of the bar beam (5) and is placed at the upstream sand (7) of the pressure shoe (6) so that it can receive lubricant which is removed from the flexible tubular jacket (15) at the beginning of the nip and by the pressure shoe (6) and the devices ( 14) for pressing the pressure shoe (6) against the counter-roller (4) are arranged so that the pressure in the nip reaches its highest value at a point which is closer to the upstream sand (7) than the downstream sand (8) of the pressure shoe (6). Shoe press (3) according to claim 1, wherein the length of the nip in the machine direction is in the range 40 mm - 120 mm and the lubrication pocket (12) is located within the first 40 percent of the length of the nip and that the pressure in the nip reaches its highest value within the first 40 percent of the length of the pinch. Shoe press (3) according to any one of claims 1 or 2, wherein the layer (11) of resilient material has a thickness in the range 20 mm - 30 mm. A shoe press (3) according to any one of claims 1-3, wherein the resilient material is polyurethane or a material comprising polyurethane and wherein the layer (11) of resilient material is bonded to the metal core (10). 10 538 0 Shoe press (3) according to any one of the preceding claims, wherein the lubrication pocket (12) has an extension in the machine direction which is in the range 3 mm - 9 mm, preferably 4 mm - 8 mm. Shoe press (3) according to any one of the preceding claims, wherein the lubrication pocket (12) is designed to gradually become shallower against the downstream sand of the lubrication pocket (12). Shoe press (3) according to any one of the preceding claims, wherein the lubrication pocket (12) is divided in the direction transverse to the machine in a plurality of separate compartments separated from each other in the direction transverse to the machine by cradles (17) formed in the layer (11) of resilient material . Shoe press (3) according to any one of the preceding claims, wherein the bar beam (5) has a pin (18) at each axial end of the bar beam (5) and wherein the devices (14) for pressing the pressure shoe (6) against the counter roller (4) ) are devices which are arranged to act on the pins (18) of the bar beam (5). Shoe press (3) according to any one of the preceding claims, wherein the pressure shoe (6) has a width in the direction transverse to the machine which is in the range 1200 mm - 2500 mm, preferably in the range 1400 mm - 2000 mm. A machine (19) for producing a laminated packaging material, which machine comprises an applicator for applying a polymeric material to a web, characterized in that the machine also comprises, following the applicator, a shoe press (3) for compressing the web and the polymeric material, wherein the shoe press (3) is a shoe press (3) according to any one of claims 1 - 9. 11 538 0 117