FI105019B - Method and apparatus for cutting a paper or board web - Google Patents

Description

1 105019

Method and apparatus for cutting a paper or board web

The invention relates to a method for cutting a paper or board web by means of a cutting stroke directed on the web. The invention also relates to 5 devices for cutting a paper or board web having an impacting member performing the cutting.

Paper or board machines or web finishing equipment, such as coating machines, use web cutter devices 10 to cut off a moving web in the event of a malfunction such as an uncontrolled web break.

Likewise, the fast moving paper or board web should be interrupted when changing the paper or board web reel when the machine roll is full, whereby the end of the web after the cutting point is guided around a new reel roll.

Currently, the following methods are used for cutting paper or board: 20

Cardboard and paper grades with a high basis weight (typically > 150 g / m 2) are cut using the so-called. bag change, or cut cord or string. The machine roll produced in bag change is retarded while blowing compressed air under the track. The course rises into a bag and ends up in 25 nipples. A sudden jerk cuts the track. In the belt change described in e.g. In U.S. Patents 4,659,029 and 4,757,850, a separate ribbon or string is provided with a gripping surface, e.g., using a sticker, on the inlet side of the nip so that the strip attaches the strip to an empty Tam drill roll surface outside the strip and

For medium grades of paper (about 80-150 g / m2), so-called paper grades are used. a swan-neck change where a small slit is cut into the web with a knife before the nip and after the nip blows compressed air to help the web 35 tear to the edges.

For thin paper grades (about less than 100 g / m2), blowing from below or from the web is used to puncture and cut the web.

2 105019

Further, there are applications using high pressure water (water jet / jets which are transported rapidly across the web) as a cutting element and various mechanically impacting blades that cut across the width of the web at the same time or moving across the web. For example, a full-width cutting cutter is shown e.g. in Finnish patent 97339.

In presently used webbing replacers, the cardboard or paper web cutter strip remains inside the machine roll being produced on the surface of the reel roll, where it causes a bottom rupture. The cardboard / paper is polished to the strip for several tens of turns. Also, due to the complex structure, the reliability of the tape changers is not good.

15

The current method of cutting the web (blows) produces particularly harmful paper chips, especially at thin paper types and high speeds, because the cutting process is not controlled. On the other hand, thicker paper grades have problems blowing with compressed air alone, 20 because compressed air cannot penetrate the web, meaning that blowing can only be used for thin grades.

Mechanically executing one or two-way rapid (transfer or cut) strokes required by the cutting event (blade cutting, etc.) leads to solutions that are not reliable and often require maintenance. Rapid mechanical movements can also pose safety risks.

The weakness of water jet cutting is the need for very fast linear movements 30 across the web and nonetheless long shear tails. For example, 2000 m / min web speed, 10 m / s cutting speed and 10 m wide web will produce a 33 m long tail. The high pressure equipment itself and the nozzles are usually quite expensive. In addition, the volumetric flow rates of the dispensing water nozzles are high and the price 35 of the full-width cut-off beam becomes high.

It is an object of the invention to provide a new method for cutting a web by a cutting stroke. To accomplish this purpose, the method according to the invention is essentially characterized in that the cutting is performed by moving the solid particles towards the surface of the ralna, whereby their short free motion motion energy provides the energy required for the cutting. At ambient temperature, the particles are solid-to-other. The change of state to harmless and easy to remove takes place at the latest after cutting off. Thus, for example, using ice particles or carbon dioxide ice, water or a gas, which is a harmless residue, is left in the cutting material, for example, as compared to using solid granules at room temperature, for example.

The particles are brought at a sufficiently high velocity to the surface of the web which: is also in motion at high velocity. The particles hit the web and puncture it with a blow which causes a rapid application of surface pressure to the web. As the piercing elements, ice granules or pellets can be used which maintain their sharp shape at the moment of impact and provide a permeation of their own kinetic energy, or carbon dioxide particles which expand strongly and thus, at the time of breaking, cause high surface pressure at the contact. The particles rapidly melt into harmless water or become directly gas (carbon dioxide).

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a side elevational view of a paper or board web roller in which the cutting device is located; Figure 5 is a schematic representation of some of the particle shapes used for cleavage.

105019

Figure 1 shows a paper or board web roller comprising a winding cylinder 1 through which the paper or board web W enters a machine roll R. The figure shows a situation where the machine roll R is a finished mass around the lamp roll 2, whereby the nip contact has been removed and the roller and roller cylinder have been separated. This is done by moving the roller R farther away from the winding cylinder 1 along the roll support structure shown in the figure as a dashed reel 2, which is provided with a center roller.

Figure 1 shows an exchange situation where a new, empty reel reel 2 is: brought into contact with web W. The web W passes a certain distance on the circumference of the reeling cylinder 1, and through the nip N between the reeling cylinder 1 and the reel reel 2, it moves to the periphery of the reel reel 2, from which it is directed towards the inflatable reel R. with the run of the web W between the roll R shortly after the point where the web 20 separates from the periphery of the reel roll 2. The arrow K also represents the direction of the cutting stroke, i.e. coming from the underside, i.e. the free sheath side of the spool reel 2, from the opposite side of the track.

Figure 2 shows the cutting device 4, which is arranged in the direction of the 25 cut-off effect in Figure 1 the direction of arrow D direction of the web W. The cutting device has a compressed air storage tank 5. The compressed air tank is connected to a series of nozzles 6 with the mouths 6a directed towards the passing Tainaa W. compressed air access to the nozzles is controlled by one or more shut-off devices which open the connection between the nozzles and the container. The nozzles in the area between the mouth opening 6a and the closing device (s) are connected to a water supply channel 7, from which water is supplied to each nozzle 6 via distribution channels 8. The nozzles 6 are disposed in an oblique position with respect to the vertical, whereby the distribution channels 8 terminating approximately perpendicular thereto are also inclined so that the gravity of water 35 from the supply channel 7 can drain to the bottom of the nozzles. Between the feed duct 7 and the nozzle 6 there may be a valve which regulates precisely the entry of a certain amount of water into the corresponding nozzle.

5 105019

The heat transfer connection to the nozzle includes a cooling element 9 which is located at the height of the bottom of the nozzle and can, for example, surround the sleeve body of the nozzle. By means of the cooling element 9, the water accumulated in the bottom part of the nozzle 5 is frozen, whereby due to the oblique position of the hole through the nozzle 6, the tip of the ice block B formed in the bottom becomes sharp.

The cutting is performed by melting the interface between the ice piece B and the inside surface of the nozzle hole with the heating element 10 in the heat transfer connection before performing the cutting stroke. The ice should only be defrosted to the extent that most of the ice remains frozen and a thin lubricating water layer forms between its surface and the inside wall of the nozzle. The closing device (s) 15 is then opened, whereupon the compressed air is exposed to the ice cubes B and fires them out of the nozzles at high speed. The ice cubes hit the sharp tip in a row above the surface of the web W and cause it to rupture, which is further ensured by the high-speed compressed air coming from the nozzles. Compressed air further ensures that the portion W of the web 20 following the cut-off point is rotated around the new reel reel 2, since the blowing direction is approximately parallel to the tangent of the reel of the reel 2 or toward the free reel of the reel.

The bottom of the nozzles 6 may be provided with sealing means separate from the compressed air guiding closure members which close and seal the bottom of the nozzle holes and prevent water from flowing down. Shortly before the compressed air is connected to the nozzles, the sealing members are removed from the road.

Fig. 3 shows an ejector cut-off device 4. The Pai-30 nipple container 5 is connected to a tube 11 which terminates in a nozzle 6. Prior to the nozzle 6, there is an ejector structure 12 with an inlet opening towards the icing granule forming unit 13. has an upper surface such that it can collect water brought in from the feed duct.

35 The substrate may be, for example, a patterned metal plate. The upper surface of the water can be determined by the outlet 15 above the base. A cooling element 9 is connected to the underside of the substrate, by means of which the water on the substrate can be frozen into granules the size of which is determined by the patterning of the substrate. The cooling element is provided with channels 9a for circulation of the cooling medium. The cooling medium may be a liquid heat transfer medium which cools the element by direct heat transfer from the element to a heat transfer medium having a temperature well below the freezing point of water.

Compressed air can be introduced into the space below the substrate from the compressed air duct 16 which insulates the substrate from the heat sink. At the same time, the compressed air bends the damper and heats it at room temperature 10, whereby the granular ice blocks B are no longer anchored to the substrate, but can be removed by external force. The valve is then opened by introducing compressed air into the tube, whereupon the suction from the ejector captures the ice cubes B from the base and directs them to the compressed air stream firing them at nozzle 6 towards passing web B and subsequent air blowing effect on web W and guiding around the new reel roll are the same as described above.

Due to the feeding method, the position of the ice cubes as they hit the web W is not predetermined. Granular ice cubes B can be made desired in the form of "wells" of the substrate, whereby sharp edges can be provided, thereby ensuring that statistically at least some of the ice cubes become sharp edges above the surface of the web. However, it should be noted that due to the high velocity, the blunt-edged pieces are also capable of piercing the web.

The devices shown in the figures can be arranged to affect the whole or a part of the width W of the web, i.e. they may be arranged to perform a full-width cut or only a portion of the width of the web. In each case, the devices are structurally constructed such that the device of Figure 2 has a plurality of adjacent nozzles communicating with the same pressurized container extending to a desired width, while the device of Figure 3 has a plurality of adjacent tubes and nozzles arranged to collect granular ice fragments. It is also possible to implement the device according to Fig. 35 by arranging the tube into a wide flow channel and the ejector structure respectively over the entire width of the substrate, whereby the tube ends in a wide nozzle slot from which the granules come in front of the desired impact width.

7 105019

Fig. 4 shows a cutting device 4 modified from the embodiment of Fig. 3. The forming base 14 is located at a suitable width and is supplied with water to be frozen transversely from the shorter 5 ends of the base, for example at both ends simultaneously. Likewise, release air to reduce contact between the frozen ice cubes and the substrate may be introduced transversely from the end of the cutting device 4, preferably at both ends simultaneously. At the rear edge of the substrate, the compressed air conduits 10 connected to the compressed air reservoir 5 at the width of the substrate, which are normally kept closed by closing devices, open. Before cutting, the contact between the ice cubes and the substrate is weakened as described above, and at the moment of cutting, the compressed air connections are opened, whereupon compressed air discharged at high speed continues to shoot ice cubes B wide against the web through narrow nozzle extensions. Preferably, the substrate and the nozzle slot 6a facing therefrom at the point of cleavage are located at a desired cleavage width substantially across the entire width of the web W, whereby a full-width cleavage can be performed. In addition, the nozzle slot can be made sufficiently tight to prevent pressure from leaking from the nozzle slot 20 prior to the granules accumulating therein, whereby the compressed air can continue to push the granules at high speed to the point of interruption. The cut-off point may be located at the same position as described above, and the air blast caused by the compressed air coming after the grain line may be used to assist in turning the web onto the reel 2 sheath.

Ice-breaking can thus be carried out either in the form of "ice shells" (pellets) or in granules of uncertain shape. Figure 5 illustrates some of the shapes of ice cubes B and the resulting "hit pattern" in the web. Computationally, it can be shown that sharp-pointed ice pellets can achieve a burst pressure of about 100 times greater than equivalent thrust, since the air hit pattern always tends to spread accurately, regardless of the nozzle structures that direct the air. The use of certain shaped "ice projectiles" that hit the web in a certain position 35 is most effective in terms of cutting because of the high impact force and local surface pressure they exert.

8 105019

The perforated nozzles 6 of the embodiment of Figure 2 provide the desired shape of the ice cube shell surface as determined by the cross-section of the hole and the tip sharpness dependent on the freezing position. It should also be noted that the ice pieces B can always be frozen in the hole nozzles 6 at the most convenient position which is independent of the position of the nozzles at the time of cutting, since after cutting the cutting device 4 can be rotated to the required position.

The invention is not limited to such a cut as is made in accordance with Figure 1 for the free run of web W. The web can also be cut in one of the ways described above also against the surface of the spool roll 2, as shown by the break arrow in Figure 1. The particles B are thus directed towards the surface of the web W at the portion through which the web passes over the spool roll 2. The advantage is that when using ice, for example, the moisture already present in the particles or resulting from them can assist in the adhesion of the web to the surface of the reel roll. The surface of the reel roll may also be grooved, whereby the impulse provided by the cutting stroke may be used to secure the end of the web to the grooves. This structure allows the end of the web to bend at least partially inward, thereby making the web more secure to follow the roll.

; 20

Carbon dioxide ice pellets (dry ice), which sublimate at the point of impact and expand at the same time, can also be used as solid bodies. These too can be fired by compressed air through the nozzles / nozzle from the tank where they are positioned below the sublimation point.

The major benefits of the solution over current cutting equipment are: 30 - High surface pressure / impact energy allows efficient punching of even / thick papers and cartons using normal compressed air; (reliability), ii short cutting no long "tail", f 9 105019 cutting can be done in the right place and direction for roll change, and air blasting following the cutting stroke can be utilized, simple design.

5

Although the above described cutting of a web in a reel during roll change, the invention can also be used at other suitable positions in a paper or board machine or in paper or board finishing equipment.

Claims (26)

105019 A method for cutting a paper or board web by means of a cutting stroke directed to the web (W) 5, characterized in that the cutting energy is achieved by utilizing the kinetic energy of solid particles (B) directed towards the surface of the moving web (W). from solid to different. Method according to claim 1, characterized in that the particles (B) are supplied with the necessary kinetic energy by coupling, behind the stationary particles (B), a pressure of a pressure medium which pushes: the particles towards the web (W). 15 A method according to claim 1, characterized in that the particles (B) are fed to a flow of gaseous pressure medium which causes the particles (B) to move towards the web (W). A method according to any one of the preceding claims, characterized in that pieces of solidified liquid are used as particles (B) which, after cleavage, are converted into a liquid under ambient conditions. Method according to Claim 4, characterized in that the pieces are sharp-pointed and are made to strike the sharp tip in front of the web (W). Method according to claim 4 or 5, characterized in that it comprises the following steps. forming pieces by solidifying the liquid, and moving the formed pieces by means of a gaseous pressure medium towards the web (W). Method according to claim 6, characterized in that it comprises the following steps: feeding a liquid into the mold structure into a cutting device (5) past which the paper or board web (W) passes, solidifying the liquid into the mold structure and moving the pieces from the mold structure by gaseous pressure medium. (W). Method according to Claim 5, 6 or 7, characterized in that the pieces are formed by solidifying the liquid in connection with the inclined wall, whereby the inclined wall and the adjacent free horizontal liquid surface form a sharp corner on the piece. Method according to one of the preceding claims 4 to 8, characterized in that the particles (B) are ice cubes formed by freezing water. Process according to one of Claims 1 to 3, characterized in that the particles (B) are solid particles which are sublimable at the moment of cleavage, such as carbon dioxide ice. A method according to any one of the preceding claims, characterized in that the cutting is carried out on a roll of paper or board in connection with a roll change. Method according to claim 11, characterized in that the cutting stroke is carried out against the surface of a new reel reel (2). A method according to any one of the preceding claims, characterized in that the cutting is carried out as a full-width cutting by applying the effect of the particles (B) to substantially the entire width of the paper or board web (W). Apparatus for cutting a paper or board web having a percussion member performing the interruption, characterized in that the percussion means (4) comprises a series of solid particles (B) which, under ambient conditions, are solidified to a different state, and B) for providing kinetic energy and corresponding movement towards the surface of the Tainan (W) moving past the cutting device (4). «105019 ϋ Device according to Claim 14, characterized in that the cutting device (4) comprises an open space (s) open towards the web (W) for holding the particles (B) in position and space in the gaseous pressure medium container (5) to effect movement toward the web (W) by pushing under pressure. Device according to Claim 14, characterized in that the cutting device (4) comprises a gaseous pressure medium flow channel (11) with an opening opening towards the web (W) and an ejector structure (12) connected to the flow channel (11) to supply particles (B). to the channel (11) and to cause their movement from its mouth toward the web (W). Apparatus according to any one of claims 14 to 16, characterized in that the particles (B) are pieces of solidified liquid having a melting point below ambient temperature. Device according to Claim 17, characterized in that the pieces are sharp-pointed and the cutting device (4) comprises spaces for positioning the pieces in an upward direction towards the web (W). Apparatus according to claim 17 or 18, characterized in that the cutting device (4) comprises a mold structure, a fluid supply port for supplying liquid to the mold structure, solidifying the cooling element fluid into the mold structure, between the gaseous pressure medium container (5) and the gaseous pressure medium container a flow connection for removing pieces of solidified liquid from the mold structure by means of a pressurizing medium discharged from the pressure medium reservoir (5) and to move them towards the web (W) by means of the pressure medium. Device according to Claim 19, characterized in that the mold-35 structure has a device separate from the pressure medium container (5) and the flow connection for reducing the contact between the mold structure and the pieces before releasing the pieces by pressure medium discharged from the pressure medium container. 13 105019 Apparatus according to claim 19 or 20, characterized in that the shape structure consists of a series of discrete hole nozzles (6). Device according to Claim 19 or 20, characterized in that the shape structure consists of a base (14) having a plurality of adjacent recesses for collecting and solidifying the liquid. Device according to one of Claims 19 to 22, characterized in that the shaped structure has a plurality of sloping walls at the height of the free horizontal liquid surface which define the space to be solidified to form sharp corners at the junction of the liquid surface and the sloping walls. Device according to one of Claims 14 to 23, characterized in that the particles (B) are solid particles sublimed to a gas at ambient temperature, such as carbon dioxide ice. Device according to one of Claims 1A to 24, characterized in that the cutting device (4) is located on a roll of paper or board. Apparatus according to one of claims 14 to 25, characterized in that the solid particles (B) are arranged in the cutting device (4) substantially across the entire width of the paper or board web (W) to perform a full-width cutting stroke. 105019