JP3691031B2 - Paper machine control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper machine for producing paper, and in particular, to a press part that presses and presses wet paper formed by a wire part and a dry part structure that dries wet paper pressed by the press part. .
[0002]
[Prior art]
In recent years, speeding up of paper machines has been promoted, and in order to be able to cope with this speeding up, moisture is maintained in a state where it is always supported by a press felt, an impermeable transfer belt, a dryer canvas (DRY felt), etc. No-open-draw paper machines that run paper have been proposed. There is no “open draw”, that is, there is no “state in which the wet paper travels in the air in a free state that is not supported by anything”, and the resistance of the traveling wet paper from the air is minimized. For this reason, it is possible to sufficiently suppress the occurrence of paper break even during high-speed operation.
[0003]
As such a paper machine without open draw, for example, techniques disclosed in US Pat. No. 4,483,745, US Pat. No. 5,792,320, US Pat. No. 5,951,821, etc. There is. FIG. 3 is a schematic side view showing the configuration from the final press to the first group dryer of the paper machine disclosed in the above-mentioned US Pat. No. 5,951,821 and US Pat. No. 5,792,320. . A web formed by a former (not shown) is pressurized and dehydrated by the upstream press device 101 and sent to the final press device 102.
[0004]
On the top side of the final press apparatus 102, for example, a top felt 102 a formed of felt having water absorbability is wound around a suction pickup roll 102 b or a top press roll 102 c, and on the bottom side of the final press apparatus 102. For example, an impermeable belt 102d formed of an impermeable material is wound around a bottom roll 102e.
[0005]
As a result, the wet paper web 120 sent from the upstream press device 101 is sucked by the suction pickup roll 102b, adsorbed to the top felt 102a, and introduced into the final press device 102 while being transferred by the top felt 102a. Both surfaces are pressed and squeezed by the nip between the top press roll 102c and the bottom press roll 102e, and this water is absorbed by the top felt 102a.
[0006]
Next to the final press apparatus 102, a dryer part 103 is provided. In the dryer part 103, the wet paper sheet 120 placed on the water-impermeable belt 102d is sucked into the suction pickup roll 103b and the dryer canvas 103a. Adsorb to. Then, the wet paper web 120 is adsorbed by the canvas 103a by the suction box 104 installed in the loop of the canvas 103a and conveyed to the first dryer cylinder 103e. Thereafter, the wet paper web 120 is reversed by the reversing roll 103f, and then conveyed to the second dryer cylinder 103g, and thereafter similarly conveyed to a reversing roll and a dryer cylinder (not shown). In the course of such conveyance, the wet paper web 120 is dried by pressing the wet paper web 120 against the dryer cylinder by the dryer canvas 103a.
[0007]
When the wet paper web 120 is pressed for dehydration by the press part including the final press device 102, its thickness decreases and at the same time a direction perpendicular to the pressurized direction (for example, running of the wet paper web 120). Direction), such elongation is generated and accumulated in the wet paper web 120 every time the pressure is applied. Accordingly, as the wet paper web 120 is further downstream in the traveling direction, the wet paper web 120 is greatly extended and the tension is lowered.
[0008]
For this reason, the peripheral speed of the suction pick-up roll 103b is set higher than the speed at which the wet paper 120 is sent from the final press 102, so that the wet paper 120 has a so-called draw, and the elongation generated in the final press 102 is increased. I try to absorb it.
[0009]
[Problems to be solved by the invention]
Incidentally, the elongation (sagging) generated in the wet paper 120 on the dryer canvas in the paper machine shown in FIG. 3 is mainly the first stage that occurs when the dryer canvas 103a is peeled off from the first dryer cylinder 103e. There is an elongation and a second stage of elongation that occurs when the wet paper web 120 is in contact with the dryer cylinder (especially the second dryer cylinder) and heated. Hereinafter, each of the first-stage elongation and the second-stage elongation will be described.
[0010]
First, the elongation in the first stage will be described together with the mechanism for removing moisture from the wet paper 120 in the dryer part 103.
The wet paper web 120 delivered to the suction pick-up roll 103b is sequentially fed to the dryer cylinders 103e, 103g,... Disposed on the downstream side, and is provided on the outer peripheral surfaces of the dryer cylinders 103e, 103g,. Each is pressed. At this time, since the peripheral surfaces of the dryer cylinders 103e, 103g,... Are formed smoothly, the wet paper web 120 has moisture, paper powder, and adhesive (hereinafter referred to as moisture, paper powder, and adhesive) on the surface. .., And is attached to the peripheral surfaces of the dryer cylinders 103e, 103g.
[0011]
In this way, when the wet paper 120 attached to the dryer cylinder is peeled off from the dryer cylinder peripheral surface, a part of the moisture on the wet paper surface remains on the dryer cylinder peripheral surface. The portion where the water from the dryer cylinder adheres is scraped or dried by a doctor blade or the like until the rotation phase of the dryer cylinder advances and the wet cylinder 120 is next contacted. It is removed from the peripheral surface of the dryer cylinder and is brought into a surface state substantially the same as that before contacting the wet paper web. That is, the amount of water adhering and the amount removed are substantially equal, and the surface of the dryer cylinder is maintained in an equilibrium state. In particular, the wet paper 120 is likely to stick to the peripheral surface of the first dryer cylinder 103e because water, paper powder, and adhesive are attached to the peripheral surface.
[0012]
For this reason, in the first dryer cylinder 103e, the wet paper web 120 is not pressed against the first dryer cylinder 103e by the dryer canvas 103a past the separation point A from the first dryer cylinder 103e of the dryer canvas 103a. Even so, the wet paper web 120 overcomes the centrifugal force and moves integrally with the peripheral surface while sticking to the peripheral surface of the first dryer cylinder 103e as shown by a broken line in FIG. become. When part of the wet paper 120 moves while sticking to the circumferential surface of the cylinder in this way, the tension of the portion gradually increases, so the wet paper 120 eventually peels off from the first dryer cylinder 103e. It will be the first stage of growth.
[0013]
Therefore, as shown in FIG. 3, a pressure difference generator (for example, a suction box) 105 is installed near the peeling point A of the first dryer cylinder 103e so as to face the wet paper 120 with the dryer canvas 103a interposed therebetween. The wet paper web 120 is sucked onto the dryer canvas 103a by the pressure difference generating device 105 so that the wet paper web 120 is prevented from sticking to the first dryer cylinder 103e.
[0014]
Further, in order to assist the pressure difference generator 105, a paper peeling doctor unit 106 and an air jet device 106a are attached to the peeling point A facing the first dryer cylinder 103e, and the paper peeling doctor unit 106 is provided. The wet paper 120 attached to the cylinder peripheral surface is peeled off by the air jet from the tip of the air jet and the air jet device 106a. Further, the reversing roll 103f for guiding the wet paper web 120 from the first dryer cylinder 103e to the second dryer cylinder 103g has the wet paper web 120 wound around the reversing roll 103f separated from the roll peripheral surface by centrifugal force. 1 dryer cylinder 103e Pasted It is configured to generate a negative pressure on its peripheral surface so as not to stick.
[0015]
However, although the first-stage elongation is suppressed in this way, it cannot be completely suppressed in practice.
In addition, as the wet paper 120 advances through the dryer part and the temperature of the wet paper 120 increases and the degree of drying increases, the viscosity of the wet paper surface decreases and the loss of the adhesive substance on the wet paper surface advances. The adhesive force to the peripheral surface of the dryer cylinder rapidly decreases. For this reason, after the second dryer cylinder, the first-stage elongation due to sticking of the wet paper web 120 to the cylinder peripheral surface is slight.
[0016]
Next, the elongation in the second stage will be described. As the wet paper 120 travels while sequentially sliding in contact with the dryer cylinders 103e and 103g, the temperature of the wet paper 120 rises, and the wet paper 120 is moistened by the expansion of the water content of the wet paper 120. Elongation occurs in the paper 120. In general, such elongation occurs larger after the second dryer cylinder 103g than in the first dryer cylinder 103e. This is because, in the first dryer cylinder 103e, the wet paper web 120 is not heated so much and the moisture in the wet paper paper 120 does not expand greatly, whereas in the second dryer cylinder 103g and thereafter, the wet paper web 120 is heated and wet. This is because the moisture contained in the paper 120 is greatly expanded. As described above, the elongation generated in the wet paper web 120 due to the expansion of the retained moisture occurs more in the second dryer cylinder 103g on the downstream side than the first-stage elongation generated in the first dryer cylinder 103e. This elongation is referred to as the second stage elongation.
[0017]
When only a few dryer cylinders are passed, the wet paper web 120 has such first-stage elongation and second-stage elongation, and the wet paper web 120 is in a slack state on the dryer canvas 103a. End up. When the wet paper is pressed against the dryer cylinder in such a state, a folding crease (Crease) is generated on the wet paper, and there is a high possibility that stress is concentrated on the crease of the fold and the paper breaks.
[0018]
U.S. Pat. No. 5,888,354 discloses a technique capable of suppressing the first-stage elongation of such a dryer part.
As shown in part in FIG. 4, this technique has a configuration in which there is no open draw between the former (not shown) and the first dryer cylinder 202a, and in a press part including the final press device 201a and the like. Elongation of the wet paper web 120 due to pressurization and squeezing is removed by applying a draw to the wet paper paper 120 with a speed difference in the press part. The felt 201c used in the final press apparatus 201a extends to the first dryer cylinder 202a, and the dryer canvas 202b is stretched over the second dryer cylinder 202d and the reverse roll 202c. The wet paper web 120 can be drawn between the dryer cylinder 202a and the second dryer cylinder 202d. As a result, the first stage elongation in the first dryer cylinder 202a can be suppressed.
[0019]
However, in this technique, the extension in the running direction of the wet paper web 120 generated in the final press device 201 having the highest dewatering pressure (nip pressure) among the press devices constituting the press part is not released immediately downstream of the nip. It will be. For this reason, microcorrugation occurs in the wet paper 120, and the wet paper 120 is caused to travel on the first dryer cylinder 202a in a state where compression distortion is retained.
[0020]
For this reason, the wet paper web 120 is pressed against the first dryer cylinder 202a by either the felt 201c or the dryer canvas 202b as a compressive strain, especially during the high speed operation of the paper machine. The stretch is released from the wet paper 120. As a result, as shown by a broken line in FIG. 4, the wet paper web 120 is peeled from the peripheral surface of the first dryer cylinder 202a between the points C and D, and is largely loosened on the peripheral surface of the first dryer cylinder 202a. End up. The position where the wet paper 120 starts to peel from the peripheral surface of the first dryer cylinder 202a between the points C and D is the centrifugal force acting on the wet paper 120, the adhesive force and the compressive strain amount of the wet paper 120, the first It changes depending on various conditions such as the nip pressure between the dryer cylinder 202a and the nip roll 201b, and the slack behavior of the wet paper web 120 peeling is unstable, causing paper breakage and making stable operation at high speed difficult.
[0021]
Further, the peripheral speed of the first dryer cylinder 202a is set to be higher than the traveling speed of the felt 201c of the final press device 201a (that is, the wet paper 120 is drawn), and the wet paper web 120 is placed downstream of the final press device. A method is also conceivable in which the generated compressive strain and thus the looseness of the wet paper 120 between the points C and D is removed. However, in order to set the peripheral speed of the first dryer cylinder 202a higher than the traveling speed of the felt 201c, the nip between the nip roll 201b and the first dryer cylinder 202a is opened by separating the nip roll 201b from the first dryer cylinder 202a. It is necessary to reduce the nip pressure.
[0022]
In this case, pressing of the wet paper 120 against the first dryer cylinder 202a by the felt 201c becomes insufficient, and transfer of the wet paper 120 to the first dryer cylinder 202a becomes unstable.
In this way, even if the paper machine is configured as a no-open draw and capable of high-speed operation, as described above, the paper breaks due to the elongation generated in the final press, the first-stage elongation generated in the dryer part, and the second-stage elongation. As a result, the operation became unstable, and in the end, high speed operation was not possible.
[0023]
The present invention was devised in view of the above-described problems, and is a paper machine capable of stably performing high speed paper making by preventing slack in wet paper. Control method The purpose is to provide.
[0027]
For this reason, Method for controlling a paper machine of the present invention (claims) 1 ) Is a belt mechanism comprising a belt-like member for supporting the wet paper formed by the wire part, and a driving means for driving the wet paper integrally with the belt-like member, and pressurizing the wet paper A press part in which one or more press means for squeezing are arranged along the pass line of the wet paper, and a dryer means for heating and drying the wet paper squeezed by the press part is a pass of the wet paper. A plurality of dryer parts arranged along a line, the pressing means located on the most downstream side in the wet paper transport direction of the press part, and the upstream of the dryer part in the wet paper transport direction From the first dryer means and the second dryer means from the upstream side in the wet paper transport direction of the dryer part, the paper machine control method provided with the belt mechanism separately, Above downstream In each of the press means, the first dryer means, and the second dryer means, the operation of the drive means of the belt mechanism is separately controlled to control the conveyance speed of the wet paper separately. The wet paper web transport speed in the first dryer means is higher than the wet paper web transport speed of the press means on the most downstream side and 1.04 times or less. It is characterized by being set to the speed of.
It is preferable to set the conveyance speed of the wet paper in the second dryer means to be higher than the conveyance speed of the wet paper in the first dryer means and 1.01 times or less ( Claim 2 ).
In the dryer part, three or more dryer means are arranged along the wet paper path line, and any one of the third and subsequent dryer means from the upstream side of the wet paper web in the dryer part, The belt mechanism is provided separately for each of the second dryer means, and the wet paper web transport speed in any of the third and subsequent dryer means is determined by the wet speed of the second dryer means. It is preferable to set at a speed higher than the paper conveyance speed and 1.01 times or less. 3 ).
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 are views showing a paper machine as one embodiment of the present invention, FIG. 1 is a schematic side view showing the configuration of the paper machine of the present invention, and FIG. 2 is a schematic diagram showing a partial configuration thereof. FIG.
[0029]
As shown in FIG. 1, the paper machine according to the present invention has upstream equipment for a wire part (paper layer forming process) X, a press part (dehydration process) Y, and a dryer part (drying process) Z. It is provided in order from the side, and has a configuration with no open draw (an unsupported space where no wet paper is supported) from the wire part X to the outlet of the press part Y. Further, although not shown, a gloss process and a winding process are further provided in this order from the upstream side downstream of the dryer part Z, and the press part Y and the dryer part are provided. Z The web that has been squeezed and dried in step 1 is smoothed in the gloss process, and is made into a paper product in the winding process.
[0030]
The wire part X includes a flow box 1 for ejecting a pulp suspension (fiber + dispersion) as a paper raw material liquid, and a pair (two sheets) of endless nets (wires) 2 that run synchronously. 3, a suction roll 4 and a wire roll 5 installed opposite to each other via the nets 2 and 3 in the upstream part of the paper layer forming process, and a dehydrating device 6 installed downstream of the nets 2 and 3 via the nets 2 and 3 7 and a suction roll 8 installed downstream via the net 3.
[0031]
The net 2 is supported by a suction roll 4, a wire roll 51, and a plurality of guide rolls 53, and travels while being driven or guided by the rolls 4, 51, 53. The net 3 is supported by a wire roll 5, a wire roll 52, and a plurality of guide rolls 54, and travels while being driven or guided by each of these rolls 5, 52, 54.
[0032]
In such a wire part X, the pulp suspension from the flow box 1 is ejected between the nets 2 and 3 that enter between the wire roll 5 and the suction roll 4 and both. It is sandwiched between the nets 2 and 3 and transferred. During this transfer, the pulp suspension is sandwiched between the meshes 2 and 3 while being dehydrated by the dehydrating devices 6 and 7, and the fibers and the dispersion are separated through the meshes to form wet paper. Go.
[0033]
The subsequent press part Y is provided with a pair (two sheets) of endless felts (belt-like members) 12 and 13 on the upstream side and a pair (two sheets) of endless felts (belt-like members) 18 and 19 on the downstream side. Is provided.
The felt 12 disposed on the most upstream side of the press part Y is wound around two suction rolls 11, a press roll 14, and a plurality of guide rolls 55 in a loop shape. Each of the rolls is provided with a motor (driving means) that drives the felt 12 integrally with the roll and thus the wet paper, and the felt 12 is driven or guided by each of the rolls 11, 14, and 55 to travel. To do. With such a configuration, the wet paper web is transported while being supported by the felt 12, and the belt mechanism of the present invention is configured by the felt 12 and the rolls 11, 14, and 55.
[0034]
The felt 13 installed facing the felt 12 is wound around the press roll 15, the suction roll 16, and the plurality of guide rolls 56 in a loop, and the press roll 15 or the suction roll 16 has a drive motor ( Drive means), and the felt 13 travels while being driven or guided by the rolls 15, 16, and 56, and the belt mechanism of the present invention is constituted by the felt 13 and the rolls 15, 16, and 56. Yes.
[0035]
The wet paper transported on the net 3 of the wire part X is sucked by the suction roll 11 and transferred to the felt 12, and the press rolls 14 and 15 are sandwiched and transported between the two felts 12 and 13 traveling. It is dehydrated by pressurizing with. Thus, the press rolls 14 and 15 constitute the pressing means of the present invention.
[0036]
Further, the wet paper that has passed through the press rolls 14 and 15 is transferred to the felt 13 by the suction roll 16 at the part where the felts 12 and 13 are separated.
A top felt (belt-like member) 18 disposed on the downstream side of the press part Y is wound around the suction roll 17, the press roll 20, and the plurality of guide rolls 57 in a loop, and the suction roll 17 or the press roll. 20 is provided with a drive motor (drive means), and the felt 18 is driven or guided by these rolls 17, 20, 57 and travels. A bottom felt (belt-like member) 19 installed facing the top felt 18 is wound around the press roll 21 and a plurality of guide rolls 58 in a loop shape, and the press roll 21 has a drive motor (drive means). The felt 19 is driven or guided by the rolls 21 and 58 and travels.
Thus, the felt 18 and the rolls 17, 20, and 57, and the felt 19 and the rolls 21 and 58 constitute the belt mechanism of the present invention.
[0037]
The wet paper transported on the felt 13 is sucked by the suction roll 17 and transferred to the felt 18, and the final press (press rolls 20, 21) while being sandwiched and transported between the two felts 18, 19 traveling. Further dehydration by pressurizing with. Thus, the press rolls 20 and 21 constitute the pressing means of the present invention. Then, the wet paper that has passed through the press rolls 20 and 21 is transferred to the felt 19 and further transferred to the dryer part Z by the suction pickup roll 23.
[0038]
In the final press, it is more preferable to use a shoe press in place of the press rolls 20 and 21, and instead of the felt 19 on the bottom side, wetness (the water squeezed from the wet paper is wet again). It is more preferable to use an impermeable transfer belt from the viewpoint of preventing absorption by paper).
As shown in FIG. 1, the upstream part of the dryer part Z includes endless canvases (belt-like members) 22a to 22c, wet paper web reversing rolls (hereinafter also simply referred to as reversing rolls) 23a to 23c, and dryers. Cylinders (dryer means) 25a to 25d and suction boxes 27a to 27d are provided. The dryer cylinders 25a to 25d are supplied with steam from an external steam source (not shown), and the wet paper 10 delivered from the press part Y is transferred to the peripheral surfaces of the dryer cylinders 25a to 25d by the canvases 22a to 22c. Are sequentially pressed and heated to dry.
[0039]
The most upstream canvas 22a is installed so as to face the most upstream cylinder (hereinafter also referred to as the first dryer cylinder) 25a as the first dryer means. The canvas 22a is a suction pickup. It is looped over the roll 23 and the plurality of guide rolls 59 and pressed against the first dryer cylinder 25a outside the loop. The canvas 22a is driven by the suction pickup roll 23 or the dryer cylinder 25a while being supported by the suction pickup roll 23, the dryer cylinder 25a, and the guide roll 59, and is guided by the guide roll 59 to travel. It has become.
[0040]
The canvas 22b on the downstream side of the canvas 22a includes a second cylinder (hereinafter also referred to as a second dryer cylinder) 25b as a second dryer means and a third cylinder (hereinafter referred to as a third cylinder) from the upstream side. (Also referred to as a dryer cylinder) 25c. The canvas 22b travels while being driven or guided while being supported by the cylinders 25b and 25c, the reversing rolls 23a and 23b, and the plurality of guide rolls 60.
[0041]
As described above, the belt mechanism and the dryer means of the present invention can be obtained by the canvas 22a, the dryer cylinder 25a and the guide roll 59, and by the canvas 22b, the cylinders 25b and 25c, the reversing rolls 23a and 23b, and the guide roll 60, respectively. It is constructed integrally.
Although only the inlet portion is shown in FIG. 1, the canvas 22c further downstream than the canvas 22b faces the fourth cylinder (hereinafter also referred to as a fourth dryer cylinder) 25d from the upstream side in the wet paper web transfer direction. It is installed and travels while being driven or guided while being supported by the cylinder 25d, the reversing roll 23c, and the plurality of guide rolls 61.
[0042]
Hereinafter, the dryer part Z will be further described with reference to FIG. In FIG. 2, the wet paper 10 is indicated by a broken line for convenience.
The wet paper 10 on the bottom felt 19 of the final press is first sucked and picked up by the suction pick-up roll 23 via the canvas 22a for the first dryer cylinder 25a, and thereafter, the wet paper 10 is picked up by the canvas 22a. It is designed to be pressed against one dryer cylinder 25a.
[0043]
Further, in the loop of the canvas 22a, a wet paper web adsorbing device (here, a suction box for generating negative pressure) 27a is installed between the suction pickup roll 23 and the first dryer cylinder 25a. The paper 10 is adsorbed on the canvas 22a to prevent the wet paper 10 from being separated from the canvas 22a while being fed from the suction pickup roll 23 to the first dryer cylinder 25a.
[0044]
The canvas 22a presses the wet paper 10 against the peripheral surface of the first dryer cylinder from the point H to the point K (the canvas 22a passes through the wet paper 10 to the peripheral surface of the first dryer cylinder. To point K). The canvas 22a separated from the peripheral surface of the first dryer cylinder 25a enters a return loop from the guide roll 59a, and returns to the suction pickup roll 23 via another guide roll, a stretcher, a cleaning device, etc. (not shown). It is like that.
[0045]
Of the guide rolls 60 that guide the travel of the second canvas 22b, the guide roll 60a disposed closest to the first dryer cylinder 25a has a moving mechanism (not shown). On the other hand, it is configured to move forward and backward as indicated by arrows in FIG. By adjusting the position of the guide roll 60a, the pass line of the second canvas 22b can be adjusted. The second canvas 22b is closest to the peripheral surface of the first dryer cylinder 25a at the point L. The pass line is set so as to make a kiss touch. Further, by adjusting the position of the guide roll 60a, the gap amount between the second canvas 22b and the first dryer cylinder 25a is adjusted, or the degree of kiss touch between the second canvas 22b and the first dryer cylinder 25a (nip pressure). Or contact amount). Such position adjustment of the guide roll 60a is appropriately set according to various conditions such as the type of the wet paper 10 and the operation speed so that the wet paper 10 does not sag.
[0046]
Here, the point L is a separation point of the wet paper web 10 from the first dryer cylinder 25a when not pressed against the first dryer cylinder 25 by the second canvas 22b. The kiss touch is a contact in which the contact between the second canvas 22b and the first dryer cylinder 25a is almost a point contact, and the nip pressure between the second canvas 22b and the first dryer cylinder 25a is almost zero. That is.
[0047]
The peripheral surface of the first dryer cylinder 25a is covered with ceramic so that the pressed wet paper 10 can be easily peeled off. Furthermore, doctor blades 28 and 29 and an air jet 35 are installed on the peripheral surface (here, the lower surface) where the wet paper web 10 of the first dryer cylinder 25a is not pressed, and the doctor blades 28 and 29 have their tips on the cylinder peripheral surface. The air jet 35 injects air onto the circumferential surface of the cylinder. The doctor blade 28 and the air jet 35 on the upstream side in the cylinder rotation direction peel off the wet paper 10 from the cylinder peripheral surface when the wet paper 10 remains attached to the cylinder peripheral surface even after passing the point L. Is for. Further, the doctor blade 29 on the downstream side in the cylinder rotation direction is for scraping off deposits from the cylinder peripheral surface to keep the cylinder peripheral surface clean. In this way, the cylinder peripheral surface is kept clean. Thus, the behavior of the wet paper 10 at the time of transition to the next stage can be stabilized (for example, the peeling position of the wet paper 10 from the cylinder peripheral surface can be kept substantially constant).
[0048]
After passing the point L, the second canvas 22b passes through the peripheral surface of the wet paper web reversing roll 23a and is pressed against the peripheral surface of the second dryer cylinder 25b, and then the wet paper web reversing roll as shown in FIG. 23b, after passing through the third dryer cylinder 25c, the guide roll 60a is further returned to the guide roll 60a via a guide roll 60, a stretcher or a cleaning device (not shown).
[0049]
In the loop of the second canvas 22b, a wet paper web adsorbing device (here, a suction box for generating a negative pressure) 27b is installed, and the wet paper web reversing roll 23a generates a negative pressure on its peripheral surface. The wet paper 10 can be adsorbed to the peripheral surface integrally with the canvas 22b. Thereby, the wet paper 10 can be stably delivered from the first canvas 22a to the second canvas 22b.
In order to stabilize the running of the wet paper 10 between the points K and L on the peripheral surface of the dryer cylinder 25a, the second canvas 22b has an air permeability of 1,000 to 4,000 cc / cm. ² ・ Min @ 1/2 ”AQ [1000-4000cm ³ / Cm ² It is preferable to use the one of min (at a differential pressure of 124.5 Pa)].
[0050]
As described above, the final press composed of the press rolls 20 and 21, the first dryer cylinder 25a and the second dryer cylinder 25b are each provided with a belt mechanism, and the felts 18 and 19 of the final press, The speeds of the canvas 22a of the first dryer cylinder 25a and the canvas 22b of the second dryer cylinder 25b can be set separately. That is, the wet paper web transport speed can be set separately by the final press and dryer cylinders 25a and 25b, and the wet paper web 10 can be drawn between each of them.
[0051]
Here, the traveling speed V of the canvas 22a of the first dryer cylinder 25a. ₁ Is, for example, the speed of the final press (that is, the traveling speed of the top felt 18 and the bottom felt 19) so that the wet paper 10 can be drawn in consideration of the elongation (about 3%) of the wet paper 10 generated in the final press. ) V ₀ Can be arbitrarily set to a high speed of 1.04 times or less (V ₀ <V ₁ ≦ 1.04V ₀ ). That is, the driving manual driving the canvas 22a (the motor that rotationally drives either the suction pickup roll 23 or the first dryer cylinder 25a) can set the traveling speed of the canvas 22a to an arbitrary speed within the above range. Is selected. V ₁ Is V ₀ If it exceeds 1.04 times, the draw becomes excessive, the strength of the wet paper is reduced, paper breakage occurs in the downstream dryer cylinder, and high speed operation becomes difficult. ₀ Of 1.0 4 Is less than double.
[0052]
Further, the traveling speed V of the canvas 22b of the second dryer cylinder 25b and the third dryer cylinder 25c. ₂ Can draw the wet paper 10 in consideration of the first stage elongation (1.0% or less, usually 0.5%) that may occur in the first dryer cylinder 25a described as the problem of the prior art. For example, V ₂ Is V ₁ Can be arbitrarily set to a speed higher than 1.01 times or less (V ₁ <V ₂ ≦ 1.01V ₁ ). That is, the driving means for driving the canvas 22b (a motor for rotating one of the reversing rolls 23a and 23b and the dryer cylinders 25a and 25b) can set the traveling speed of the canvas 22b to an arbitrary speed within the above range. Is selected.
[0053]
Furthermore, here, as described above, the dryer cylinders 25b and 25c and the fourth dryer cylinder 25d are each provided with a belt mechanism. Thereby, the speed of the canvas 22b of the dryer cylinders 25b and 25c and the speed of the canvas 22c of the fourth dryer cylinder 25d can be set separately. The wet paper web transport speed in the dryer cylinders 25b and 25c, The wet paper web transfer speed in the fourth dryer cylinder 25d can be set separately.
[0054]
In general, in the dryer part, the wet paper quickly rises in the process of passing through several dryer cylinders on the upstream side, but usually reaches an equilibrium state at about 80 ° C., and thereafter the moisture in the wet paper The evaporation of is performed at a constant temperature. If the temperature of the wet paper at the inlet of the dryer part is 20 ° C., the expansion coefficient of water when the temperature is raised from 20 ° C. to 80 ° C. is about 2.7%. Since wet paper has fiber orientation, the degree of expansion varies depending on the orientation, but assuming that it expands evenly in any direction, the expansion coefficient is about 1% when converted to a linear expansion coefficient. It becomes. That is, the second stage elongation of the wet paper 10 is about 1%.
[0055]
Therefore, the traveling speed V of the canvas 22c of the fourth dryer cylinder 25d. ₃ , The traveling speed V of the upstream canvas 22b ₂ If it is set to about 1.01 times, the elongation of the second stage of the wet paper 10 can be absorbed, and the drive source for driving the canvas 22c (for example, the motor for driving the dryer cylinder 25c to rotate) is driven by the canvas 22c. Those that can set the speed to the above speed are selected.
[0056]
In the dryer part Z, since the second stage of elongation occurs in the wet paper web 10 until the temperature of the wet paper paper 10 reaches about 80 ° C., which is the above-described equilibrium temperature, the canvas loop and the canvas loop for each dry cylinder are generated. It is preferable to adopt a configuration in which each of the driving sources for driving each is driven at a predetermined speed (a configuration having a belt mechanism separately). However, as described above, the temperature rise of the wet paper web 10 (ie, the second stage elongation) is large near the inlet of the dryer part Z, and on the downstream side, the temperature rise of the wet paper web 10 (ie, the second stage elongation). ) Is almost eliminated, and the dryer cylinder on the downstream side of the second dryer cylinder 25b is absorbed so that at least the elongation of the wet paper web 10 generated on the second dryer cylinder 25b can be absorbed from the test results by the inventors' pilot machine. On the other hand, it has been found that if at least one belt mechanism is provided separately from the belt mechanism of the second dryer cylinder 25b, the slack of the wet paper web 10 can be sufficiently suppressed.
[0057]
The paper machine as one embodiment of the present invention is configured as described above, and the final press speed V ₀ Than the speed V of the first canvas 22a ₁ Is set high (V ₀ <V ₁ Thus, when absorbing the elongation of the wet paper 10 that occurs in the final press, the first stage of elongation occurs in the wet paper 10 on the first dryer cylinder 25a as in the prior art. Speed V of the second canvas 22b ₂ Is the speed V of the first canvas 22a. ₁ Higher than (V ₁ <V ₂ ) Can be absorbed.
[0058]
Accordingly, the wet paper web 10 can be sent to the second dryer cylinder 25b without being loosened on the second canvas 22b, and the wet paper web 10 is almost completely transferred to the second canvas 22b, the reversing roll 23a, and the second dryer cylinder 25b. Thus, it becomes possible to almost completely prevent paper breakage due to stress concentration caused by wrinkles due to loosening of the wet paper.
[0059]
Also, here, the dryer cylinders 25b and 25c, both of which are overlaid with the second canvas 22b, are overwhelmed with the third canvas 22c, and the traveling speed of the second canvas 22b and the third canvas 22c. Can be set separately.
Accordingly, in the process in which the wet paper web 10 is gradually dried as it advances through the dryer part Z, the wet paper web 10 is stretched particularly after the second dryer cylinder 25b, but the speed of the third canvas 22c is increased to the second canvas 22b. If the wet paper 10 is drawn at a speed higher than the speed of the paper, the above-mentioned elongation can be absorbed and the wet paper 10 can be prevented from slackening on the third canvas 22c, thereby preventing paper breakage. become able to.
[0060]
Even if the speed of the wet paper is increased, the running of the wet paper 10 in the dryer part Z is stabilized in this way, and the frequency of the paper break can be greatly reduced as compared with the conventional speed. Paper making at a high speed such as / min is possible.
[0061]
In addition, the paper machine of this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, the second dryer cylinder 25b and the third dryer cylinder 25c share one belt mechanism. However, the second dryer cylinder 25b and the third dryer cylinder 25c separately provide belt mechanisms. The wet paper web 10 may be drawn between the dryer cylinders 25b and 25c. As a result, the second-stage elongation generated in the wet paper 10 in the second dryer cylinder 25b can be absorbed at an early stage.
[0062]
Further, the traveling speeds V of the felts 18, 19 and the canvases 22a, 22b, 22c ₀ , V ₁ , V ₂ , V ₃ Is not limited to the numerical range exemplified in the embodiment, and is appropriately set so as to absorb the elongation of the wet paper 10.
[0065]
Book Invention paper machine control method (claims) 1 ), The pressing means located on the most downstream side in the wet paper transport direction of the press part, the first dryer means from the upstream side of the wet paper transport direction of the dryer part, and the wet paper transport direction of the dryer part The belt mechanism is provided separately for the second dryer means from the upstream side, and in the press means on the most downstream side, the first dryer means, and the second dryer means, the belt mechanism By controlling the operation of the drive means separately and setting the wet paper web transfer speed separately, the wet paper web feed speed in the first dryer means is set to the wet paper web feed of the press means on the most downstream side. It is possible to set the speed higher than the speed, and to set the wet paper transport speed in the second dryer means to a speed higher than the wet paper transport speed in the first dryer means. Becomes ability, thereby, it is possible to prevent looseness occurs in the paper wet before and after the first th dryer means to prevent web breaks, there is an advantage of the so performed stably with high-speed papermaking. In particular, the wet paper web transport speed in the first dryer means is set to a speed higher than the wet paper web transport speed of the press means on the most downstream side and 1.04 times or less. Thus, paper cutting at high speed can be stably performed.
In addition, the wet paper web is effectively transferred by setting the wet paper web transfer speed in the second dryer means to be higher than the wet paper web feed speed in the first dryer means and 1.01 times or less. The paper cutting at a high speed can be stably performed by suppressing the paper breakage of the paper. 2 ).
Further, in the dryer part, three or more dryer means are arranged along the wet paper pass line, and any one of the third and subsequent dryer means from the upstream side of the wet paper transport direction of the dryer part, and the second dryer means. The belt mechanism is provided separately, and the wet paper transport speed in any of the third and subsequent dryer means is higher than the wet paper transport speed in the second dryer means and 1.01 times or less. If this speed is set, it will be possible to absorb the expansion of the wet paper due to heating mainly generated in the second dryer means, and to suppress the loosening of the wet paper more effectively. (Claim 3) .
[Brief description of the drawings]
FIG. 1 is a schematic side view showing a configuration of a main part of a paper machine as an embodiment of the present invention.
FIG. 2 is a schematic side view showing a partial configuration of a paper machine as an embodiment of the present invention.
FIG. 3 is a schematic side view showing a configuration from a final press to a dryer part inlet of a conventional paper machine.
FIG. 4 is a schematic side view showing a configuration from a final press to a dryer part inlet of a conventional paper machine.
[Explanation of symbols]
1 Flow box
2,3 mesh (wire)
4,8,16 Suction roll
5,51 Wire roll
6,7 Dehydration equipment
10 wet paper
12, 13, 18, 19 Felt (belt-shaped member)
14, 15, 20, 21 Press roll (pressing means)
22a-22c canvas (belt-shaped member)
23 Suction Pickup Roll
23a-23c Wet paper reversing roll
25a-25d Dryer cylinder (Dryer means)
27a-27d Suction box
28, 29 Doctor blade
35 Air Jet
53-61, 60a Guide roll
V ₀ Belt speed at final press
V ₁ Belt speed in the first dryer cylinder
V ₂ Belt speed in the second dryer cylinder
X wire part (paper layer forming process)
Y press part (dehydration process)
Z dryer part (drying process)

Claims (3)

A belt mechanism comprising: a belt-like member that supports a wet paper formed by a wire part; and a driving unit that drives the wet paper integrally with the belt-like member;
A press part in which one or more press means for pressing and squeezing the wet paper are arranged along the pass line of the wet paper;
A dryer means that heats and dries the wet paper squeezed by the press part is provided with a dryer part that is arranged in a plurality along the pass line of the wet paper,
A pressing means located on the most downstream side in the wet paper transport direction of the press part; a first dryer means from the upstream side of the wet paper transport direction of the dryer part; and transporting the wet paper of the dryer part A control method for a paper machine in which the belt mechanism is separately provided with the second dryer means from the upstream side in the direction,
In the pressing means on the most downstream side, the first dryer means, and the second dryer means, the operation of the driving means of the belt mechanism is controlled separately, and the wet paper web In addition to setting the transport speed of
The conveyance speed of the wet paper in the first dryer means is set to be higher than the conveyance speed of the wet paper of the press means on the most downstream side and 1.04 times or less. And a paper machine control method. The wet paper web transport speed in the second dryer means is set to be higher than the wet paper web transport speed in the first dryer means and 1.01 times or less. The method of controlling a paper machine according to claim 1 . In the dryer part, three or more dryer means are arranged along the wet paper path line, and any one of the third and subsequent dryer means from the upstream side of the wet paper web in the dryer part, With the second dryer means, the belt mechanisms are provided separately,
The conveying speed of the wet paper in any of the third and subsequent dryer means is set at a speed higher than the conveying speed of the wet paper in the second dryer means and 1.01 times or less. characterized in that, the control method according to claim 1 or 2, wherein the paper machine.

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