CN207210832U - A kind of top net former of gradual dehydration - Google Patents

Abstract

The utility model discloses a progressive dehydration top wire former, which comprises an annular top wire and a plurality of forming rollers, the annular top wire is arranged above the bottom wire, and a wet paper delivery channel is formed between the ring top wire and the bottom wire; There are multiple forming rollers on the connecting part of the annular top wire and the bottom wire, and the multiple forming rollers are alternately located above the annular top wire and below the bottom wire, and each forming roller corresponds to a dehydration zone; along the conveying direction of the wet paper sheet , the diameter of the forming roll decreases gradually, and the dehydration pressure in the dehydration zone gradually increases. Its dehydration method is to use the pressure of multiple dehydration zones to gradually increase, and perform multi-stage dehydration on wet paper sheets. The utility model can realize progressive dehydration, slow down the speed of dehydration forming of wet paper sheets, and thus can better meet the production requirements of high quantitative paper.

Description

A progressive dewatering top wire former

technical field

The utility model relates to the technical field of pulping and papermaking, in particular to a progressive dehydration top wire former.

Background technique

The traditional fourdrinier paper machine relies on one side for dehydration, so that the retention of fillers and fine fibers on the web side is low, and the web side of the formed paper is rougher than the front side, resulting in a large difference between the two sides of the paper. At the same time, with the dehydration of the wire part, the concentration of the pulp layer continues to increase, and the fibers in the pulp layer begin to flocculate, and as the concentration increases, the degree of flocculation also begins to intensify, resulting in poor uniformity of the paper surface .

At present, in some paper mills, in order to improve the paper formation of fourdrinier paper machines, in addition to selecting a good headbox, they often increase the traditional wire table shaking or add finishing rollers to improve the paper surface uniformity and reduce the two-sided Poor, but the improvement effect is not obvious, and these methods can only be used on low-speed paper machines. Once the speed of the paper machine exceeds 250m/min, the role of the traditional screen shaking and finishing rolls will be limited. More importantly, the finishing roller does not have the function of dewatering. The fourdrinier section using the finishing roller is still dewatering on one side, which cannot fundamentally solve the problem of paper double-sidedness, and has an effect on improving paper evenness and reducing two-sidedness. very small. Therefore, in order to further improve the paper quality of fourdrinier forming, the top wire former is a good choice.

The top wire former refers to adding a forming wire above the fourdrinier paper machine screen before the wet paper web is shaped. The extrusion and hydraulic action between them can disperse the fiber flocculation, reduce the fiber flocculation in the wet paper sheet, improve the evenness of the paper sheet, reduce the difference between the two sides of the paper sheet structure, so as to achieve the purpose of significantly improving the quality of the paper sheet.

At present, the top wire former can be simply divided into roller type top wire former, scraper type top wire former and hybrid top wire former from the structure. The roller type top wire former is mainly composed of rollers. The extrusion force between the rollers and the centrifugal force of the rollers dewater, and the dehydration efficiency is very high. At the same time, the friction between the bottom wire and the top wire is mainly rolling friction, which has little wear on the wire and reduces the load on the wire. Therefore, in the production of tissue paper has been very widely used.

However, since the traditional roll-type top wire former has only one dewatering forming area, most of the dehydration process of the top wire dehydration is completed in this area, and the extrusion force in the dehydrating forming area is very large, so when producing high-weight paper, on the one hand, , Too much dehydration pressure will damage the fiber layer and deteriorate the product performance, especially the strength performance, including printing performance, and the paper will be broken in severe cases; It is extruded and flows to both sides and the direction of the headbox, which also causes forming deterioration and affects the final paper quality.

Utility model content

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a progressive dehydration top wire former, which can realize progressive dehydration and slow down the speed of dehydration forming of wet paper sheets, thereby better Meet the production requirements of high weight paper.

The technical scheme of the utility model is: a progressive dehydration top wire former, including an annular top wire and a plurality of forming rollers, the annular top wire is arranged above the bottom wire, and wet paper is formed between the ring top wire and the bottom wire Page conveying channel; there are multiple forming rollers at the junction of the annular top wire and the bottom wire, and the multiple forming rollers are alternately located above the annular top wire and below the bottom wire, and each forming roller corresponds to a dehydration zone; along the wet paper In the conveying direction of the sheet, the diameter of the forming roller decreases gradually, and the dehydration pressure in the dehydration zone gradually increases.

As a preferred solution, there are four forming rolls, along the conveying direction of the wet paper sheet, they are the first lower forming roll, the first upper forming roll, the second lower forming roll and the second upper forming roll, wherein, The first lower forming roller is arranged under the bottom wire, and the junction of the first lower forming roller and the bottom wire forms the first dehydration zone, the first upper forming roller is arranged above the annular top wire, and the first upper forming roller and the annular The junction of the top wire forms the second dehydration zone, the second lower forming roll is set under the bottom wire, and the junction of the second lower forming roll and the bottom wire forms the third dehydration zone, and the second upper forming roll is set on the ring Above the top wire, and the junction of the second upper forming roller and the ring top wire forms the fourth dehydration zone. Among them, the first lower forming roller adopts a grooved roller, and the wet paper above the roller is squeezed by two wires (namely, the annular top wire and the bottom wire), and the water discharged downward can be drained through the grooves to reduce the occurrence of embossing. . The second upper forming roller is used as a driving roller to drive the top wire to rotate circularly with the operation of the bottom wire. The first upper forming roller and the second upper forming roller can be adjusted up and down, so as to adjust the depth of the annular top wire pressed into the bottom wire, and at the same time adjust the extrusion force of the two wires on the wet paper and the tension of the two wires to adjust the wire part The purpose of dehydration distribution on both sides, optimization of forming, and improvement of evenness.

A first water receiving tank is provided above the annular top net at the first dehydration area, and a second water receiving tank is provided above the annular top net at the third dehydration area; the first water receiving tank and the second water receiving tank have the same structure, with The wiper blade is in contact with the surface of the annular top net.

A vacuum box is set between the second dehydration zone and the third dehydration zone, and the vacuum box is set under the bottom net.

The output end of the fourth dehydration zone is provided with a suction roll, the suction roll is located under the bottom wire, and the suction roll is a vacuum roll connected with a vacuum pump. When the two wires pass through the suction roller, the wet paper sticks to the bottom wire, and continues to move forward with the bottom wire to enter the next section, instead of turning away with the top wire, so as to ensure the normal operation of the paper machine.

The two outer sides of the plurality of forming rollers are provided with lead-in rollers and lead-out rollers respectively, a first included angle is formed between the annular top net and the bottom net at the lead-in rollers, and a second angle is formed between the annular top net and the bottom net at the lead-out rollers. Two included angles, the angle of the first included angle is smaller than the angle of the second included angle. In actual production, the heights of the lead-in roller and the lead-out roller can be adjusted according to actual process requirements, thereby adjusting the angles of the first included angle and the second included angle.

The inner side of the ring-shaped top wire is also provided with a mist suction box, a return roller, a correction roller and a tension roller. The water tank, the second upper forming roller, the lead-out roller, the mist suction box, the return roller, the correction roller and the tension roller are sequentially arranged on the inner side of the annular top wire; the outer side of the ring top wire corresponding to the mist suction box is also equipped with a high pressure water spray pipe .

The depth of the first upper forming roller pressed into the bottom net is 50mm-300mm, the depth of the second upper forming roller pressed into the bottom net is 250mm-500mm; and the depth of the second upper forming roller pressed into the bottom net is deeper than the first upper The depth that the forming roller presses into the bottom net is 150mm-300mm deep. According to the quantitative factors of the paper sheet in the actual production, the pulp seed material and other factors, the actual depth of the first upper forming roller and the second upper forming roller pressed into the bottom wire can be adjusted.

The diameter of the first lower forming roll is 1.05 to 1.2 times the diameter of the first upper forming roll, the diameter of the first upper forming roll is 1.1 to 1.4 times the diameter of the second lower forming roll, and the diameter of the second lower forming roll is 1.05 to 1.2 times the diameter of the second upper forming roller, and the diameter of the second upper forming roller is not less than 400 mm.

In the above-mentioned device structure, the components that make up the top wire former are all fixedly installed on the frame, and there is also a white water tray under the bottom wire to receive the water generated in each dehydration zone.

A progressive dehydration dehydration method can be realized through the top wire former, comprising the following steps:

(1) After the wet paper sheet enters the wet paper sheet conveying channel formed between the annular top wire and the bottom wire, it first enters the first dehydration zone, and in the first dehydration zone, the first lower forming roller performs preliminary extrusion dehydration;

During the squeeze dehydration process, the water protruding upward is drained from the first water receiving tank, and the wiper blade of the water receiving tank is in contact with the surface of the annular top net, on the one hand scraping away the water protruding upward from the annular top net, and on the other hand The paper produces pressure pulsation and improves forming;

(2) After the initial extrusion dehydration is completed, the wet paper sheet continues to be conveyed forward and enters the second dehydration zone. Under the extrusion of the annular top wire and the bottom wire, combined with the centrifugal force of the first upper forming roller, the wet paper sheet is Carry out the second extrusion dehydration;

During the extrusion dehydration process, the generated water goes down into the white water tray and drains away, and the water attached to the bottom net is discharged through the vacuum box;

(3) After the second extrusion dehydration is completed, the dryness of the wet paper sheet increases and the thickness decreases at this time. After the wet paper sheet is sent to the third dehydration zone, the extrusion force and pressure of the annular top wire and bottom wire are increased at the same time. The centrifugal force of the second lower forming roller performs the third squeeze dehydration on the wet paper;

During this process, the dryness of the wet paper after dehydration in the first dehydration zone and the second dehydration zone has been relatively large, the thickness of the wet paper has been reduced, and it can withstand a large extrusion force between the two wires, so the first In the third dehydration zone, the extrusion force of the two nets increases, the centrifugal dehydration force increases, and the water that escapes upward is drained from the second water receiving tank;

(4) The wet paper sheets that have completed the third extrusion dehydration are sent to the fourth dehydration zone, and the extrusion force of the annular top wire and bottom wire and the centrifugal force of the second lower forming roller are further increased, and the wet paper sheets are subjected to the fourth dehydration process. secondary extrusion dehydration;

During this process, the water released by the extrusion of the two wires and the centrifugal force of the second upper forming roller goes down into the white water tray and is drained away, and the water attached to the bottom net is discharged through the suction roller, and the dehydration process of the wet paper sheet is completed so far.

The principle of the above-mentioned top wire former and its dehydration method is as follows: in the progressively dewatered top wire former, four forming rolls with gradually shrinking diameters are set along the advancing direction of the wet paper sheet, and the two upper forming rolls (i.e. The first upper forming roller and the second upper forming roller) have different depths of pressing into the bottom wire, so that the depth of pressing into the bottom wire increases along the advancing direction of the wet paper sheet, due to the dehydration extrusion force of the two wires on the wet paper sheet It is inversely proportional to the centrifugal force and the radius of the forming roller, thus forming four dehydration zones where the extrusion force gradually increases, so that the extrusion force and centrifugal force on the wet paper sheet in the top wire increase slowly, and the wet paper sheet is in a suitable dehydration forming effect. It can be formed slowly under the pressure of the top wire, thereby avoiding the problems of excessive dehydration pressure damage to the fiber layer, deterioration of the forming, and extrusion of the pulp in the top wire nip area during the use of the high-weight paper in the top wire. In quantitative paper production, roll top wire formers are used to increase dehydration and optimize forming, while slow dehydration is more conducive to improving the retention rate of fillers and fine fibers, improving paper quality and reducing production costs.

Compared with the prior art, the utility model has the following beneficial effects:

The top wire former and its dewatering method set a plurality of forming rollers at the junction of the annular top wire and the bottom wire to form multiple dehydration zones, and use the gradually increasing dehydration pressure to perform multi-stage dehydration on the wet paper, thereby avoiding The problem of excessive dehydration pressure damage to the fiber layer, deterioration of forming and extrusion of pulp in the nip area of the top wire that existed in the use of high-weight paper in the top wire has been solved, and the use of roller tops in the production of high-weight paper has been achieved. The purpose of the web former is to increase dehydration and optimize forming, while slow dehydration is more conducive to improving the retention rate of fillers and fine fibers, improving paper quality and reducing production costs. This top wire former adopts progressive dehydration to slow down the speed of dehydration and forming of wet paper sheets, which can better meet the production requirements of high-weight paper.

Description of drawings

Figure 1 is a schematic diagram of the principle of the top wire former.

Detailed ways

The utility model will be further described in detail below in conjunction with the examples, but the implementation of the utility model is not limited thereto.

Example

A kind of top wire former of progressive dehydration of the present embodiment, as shown in Figure 1, comprises annular top wire 16 and four shaping rollers, and annular top wire is arranged on bottom wire 17 tops, and between ring top wire and bottom wire A wet paper sheet conveying channel 18 is formed; four forming rollers are arranged at the junction of the annular top wire and the bottom wire, and the four forming rollers are alternately located above the annular top wire and below the bottom wire, and each forming roller corresponds to a dehydration zone ; Along the conveying direction of the wet paper sheet (as shown by the single arrow in Figure 1), the diameter of the forming roll decreases gradually, and the dehydration pressure in the dehydration zone gradually increases.

Along the conveying direction of the wet paper sheet, the four forming rolls are the first lower forming roll 1, the first upper forming roll 2, the second lower forming roll 4 and the second upper forming roll 5, wherein the first lower forming roll is set Below the bottom wire, the first dehydration zone I is formed at the junction of the first lower forming roll and the bottom wire, the first upper forming roll is set above the ring-shaped top wire, and the connection between the first upper forming roll and the ring-shaped top wire The second dehydration zone II is formed at the position, the second lower forming roll is set under the bottom wire, and the connection between the second lower forming roll and the bottom wire forms the third dehydration zone III, and the second upper forming roll is set above the annular top wire , and the junction of the second upper forming roll and the annular top wire forms the fourth dehydration zone IV. Among them, the first lower forming roller adopts a grooved roller, and the wet paper above the roller is squeezed by two wires (namely, the annular top wire and the bottom wire), and the water discharged downward can be drained through the grooves to reduce the occurrence of embossing. . The second upper forming roller is used as a driving roller to drive the top wire to rotate circularly with the operation of the bottom wire. The first upper forming roller and the second upper forming roller can be adjusted up and down, so as to adjust the depth of the annular top wire pressed into the bottom wire, and at the same time adjust the extrusion force of the two wires on the wet paper and the tension of the two wires to adjust the wire part The purpose of dehydration distribution on both sides, optimization of forming, and improvement of evenness.

The first water receiving tank 7 is arranged above the annular top net at the first dehydration area, and the second water receiving tank 8 is arranged above the annular top net at the third dehydration area; the first water receiving tank and the second water receiving tank have the same structure, with The wiper blade is in contact with the surface of the annular top net. A vacuum box 3 is arranged between the second dehydration zone and the third dehydration zone, and the vacuum box is arranged under the bottom net. The output end of the fourth dehydration zone is provided with a suction roll 6, which is located under the bottom wire, and the suction roll is a vacuum roll connected with a vacuum pump. When the two wires pass through the suction roller, the wet paper sticks to the bottom wire, and continues to move forward with the bottom wire to enter the next section, instead of turning away with the top wire, so as to ensure the normal operation of the paper machine.

The two outer sides of the four forming rollers are respectively provided with a lead-in roller 15 and a lead-out roller 9, the first angle is formed between the annular top net and the bottom net at the lead-in roller place, and the second angle is formed between the annular top net and the bottom net at the lead-out roller place. Two included angles, the first included angle is very small, and the second included angle is relatively large, so that the top net can be separated from the wet paper as soon as possible. In actual production, the heights of the lead-in roller and the lead-out roller can be adjusted according to actual process requirements, thereby adjusting the angles of the first included angle and the second included angle.

The inner side of the annular top wire is also provided with a mist suction box 11, a return roller 12, a correction roller 13 and a tension roller 14. Along the circular rotation direction of the annular top wire, the introduction roller, the first water receiving tank, the first upper forming roller, the second The second water tank, the second upper forming roller, the lead-out roller, the mist suction box, the return roller, the correction roller and the tension roller are sequentially arranged on the inner side of the annular top wire; water pipe10.

The depth that the first upper forming roller presses into the bottom net is 150 mm, and the depth that the second upper forming roll presses into the bottom net is 400 mm. According to the actual process requirements, the depth adjustment range of the first upper forming roller pressing into the bottom wire can be 50mm~300mm, and the depth adjustment range of the second upper forming roller pressing into the bottom wire can be 250mm~500mm; and the second upper forming roller The depth pressed into the bottom net is 150mm-300mm deeper than the depth of the first upper forming roller pressed into the bottom net. According to the quantitative factors of the paper sheet in the actual production, the pulp seed material and other factors, the actual depth of the first upper forming roller and the second upper forming roller pressed into the bottom wire can be adjusted. In this way, the pressing depth of the ring-shaped top wire into the bottom wire can be adjusted, and the extrusion force of the two wires on the wet paper sheet and the tension of the two wires can be adjusted at the same time, so as to achieve the purpose of adjusting the dehydration distribution on both sides of the wire part, optimizing the forming, and improving the evenness.

The diameter of the first lower forming roll is 700 mm, the diameter of the first upper forming roll is 650 mm, the diameter of the second lower forming roll is 550 mm, and the diameter of the second upper forming roll is 500 mm. According to actual production needs, the diameters of the four forming rolls can be adjusted. Generally, the diameter of the first lower forming roll is 1.05 to 1.2 times the diameter of the first upper forming roll, and the diameter of the first upper forming roll is the second lower forming roll. 1.1 to 1.4 times the diameter of the roller, the diameter of the second lower forming roller is 1.05 to 1.2 times the diameter of the second upper forming roller, and the diameter of the second upper forming roller is not less than 400 mm.

In the above-mentioned device structure, all components that make up the top wire former are fixedly installed on the frame, and a white water tray is provided under the bottom wire to receive the moisture generated in each dehydration zone, and the forming rollers can be rubber rollers.

In this embodiment, a dehydration method for progressive dehydration is realized by the above-mentioned top wire former, including the following steps:

(1) After the wet paper sheet enters the wet paper sheet conveying channel formed between the annular top wire and the bottom wire, it first enters the first dehydration zone, and in the first dehydration zone, the first lower forming roller performs preliminary extrusion dehydration;

During the squeeze dehydration process, the water protruding upward is drained from the first water receiving tank, and the wiper blade of the water receiving tank is in contact with the surface of the annular top net, on the one hand scraping away the water protruding upward from the annular top net, and on the other hand The paper produces pressure pulsation and improves forming;

(2) After the initial extrusion dehydration is completed, the wet paper sheet continues to be conveyed forward and enters the second dehydration zone. Under the extrusion of the annular top wire and the bottom wire, combined with the centrifugal force of the first upper forming roller, the wet paper sheet is Carry out the second extrusion dehydration;

During the extrusion dehydration process, the generated water goes down into the white water tray and drains away, and the water attached to the bottom net is discharged through the vacuum box;

(3) After the second extrusion dehydration is completed, the dryness of the wet paper sheet increases and the thickness decreases at this time. After the wet paper sheet is sent to the third dehydration zone, the extrusion force and pressure of the annular top wire and bottom wire are increased at the same time. The centrifugal force of the second lower forming roller performs the third squeeze dehydration on the wet paper;

During this process, the dryness of the wet paper after dehydration in the first dehydration zone and the second dehydration zone has been relatively large, the thickness of the wet paper has been reduced, and it can withstand a large extrusion force between the two wires, so the first In the third dehydration zone, the extrusion force of the two nets increases, the centrifugal dehydration force increases, and the water that escapes upward is drained from the second water receiving tank;

(4) The wet paper sheets that have completed the third extrusion dehydration are sent to the fourth dehydration zone, and the extrusion force of the annular top wire and bottom wire and the centrifugal force of the second lower forming roller are further increased, and the wet paper sheets are subjected to the fourth dehydration process. secondary extrusion dehydration;

During this process, the water released by the extrusion of the two wires and the centrifugal force of the second upper forming roller goes down into the white water tray and is drained away, and the water attached to the bottom net is discharged through the suction roller, and the dehydration process of the wet paper sheet is completed so far.

The principle of the above-mentioned top wire former and its dehydration method is as follows: in the progressively dewatered top wire former, four forming rolls with gradually shrinking diameters are set along the advancing direction of the wet paper sheet, and the two upper forming rolls (i.e. The first upper forming roller and the second upper forming roller) have different depths of pressing into the bottom wire, so that the depth of pressing into the bottom wire increases along the advancing direction of the wet paper sheet, due to the dehydration extrusion force of the two wires on the wet paper sheet It is inversely proportional to the centrifugal force and the radius of the forming roller, thus forming four dehydration zones where the extrusion force gradually increases, so that the extrusion force and centrifugal force on the wet paper sheet in the top wire increase slowly, and the wet paper sheet is in a suitable dehydration forming effect. It can be formed slowly under the pressure of the top wire, thereby avoiding the problems of excessive dehydration pressure damage to the fiber layer, deterioration of the forming, and extrusion of the pulp in the top wire nip area during the use of the high-weight paper in the top wire. In quantitative paper production, roll top wire formers are used to increase dehydration and optimize forming, while slow dehydration is more conducive to improving the retention rate of fillers and fine fibers, improving paper quality and reducing production costs.

As mentioned above, the utility model can be better realized, and the above-described embodiment is only a preferred embodiment of the utility model, and is not used to limit the scope of implementation of the utility model; that is, all equal changes made according to the contents of the utility model and modifications are all covered by the scope of protection required by the claims of the present utility model.

Claims (9)

1. A top wire former for progressive dehydration, characterized in that it comprises an annular top wire and a plurality of forming rollers, the annular top wire is arranged above the bottom wire, and forms a wet sheet conveyance between the ring top wire and the bottom wire channel; the connecting part of the annular top wire and the bottom wire is provided with multiple forming rollers, and the multiple forming rollers are alternately located above the annular top wire and below the bottom wire, and each forming roller corresponds to a dehydration zone; along the wet paper sheet In the conveying direction, the diameter of the forming roller decreases gradually, and the dehydration pressure in the dehydration zone gradually increases. 2. A progressive dehydration top wire former according to claim 1, characterized in that there are four forming rollers, along the conveying direction of the wet paper sheet, successively the first lower forming roller, the first upper forming roll, the second lower forming roll and the second upper forming roll, wherein the first lower forming roll is arranged below the bottom wire, and the connection between the first lower forming roll and the bottom wire forms the first dehydration zone, and the first upper The forming roller is arranged above the annular top wire, and the junction of the first upper forming roller and the annular top wire forms the second dehydration zone, the second lower forming roller is arranged under the bottom wire, and the second lower forming roller and the bottom wire The junction forms the third dehydration zone, the second upper forming roller is arranged above the annular top wire, and the junction of the second upper forming roller and the annular top wire forms the fourth dehydration zone. 3. A progressive dewatering top wire former according to claim 2, characterized in that a first water receiving tank is arranged above the annular top wire at the first dehydration area, and the annular top at the third dehydration area There is a second water receiving tank above the net; the first water receiving tank and the second water receiving tank have the same structure, with a wiper, and the wiper is in contact with the surface of the annular top net. 4. A progressive dehydration top wire former according to claim 2, characterized in that a vacuum box is provided between the second dehydration zone and the third dehydration zone, and the vacuum box is arranged under the bottom wire. 5. according to the said a kind of progressive dehydration top wire former of claim 2, it is characterized in that, the output end of described 4th dehydration area is provided with suction roll, and suction roll is positioned at bottom wire below, and suction roll is Vacuum roll with external vacuum pump. 6. A progressive dehydration top wire former according to claim 2, characterized in that, the two outer sides of the plurality of forming rollers are respectively provided with lead-in rollers and lead-out rollers, the ring-shaped top wire at the lead-in rollers and the bottom A first included angle is formed between the nets, a second included angle is formed between the annular top net and the bottom net at the outlet roller, and the angle of the first included angle is smaller than the angle of the second included angle. 7. A progressive dehydration top wire former according to claim 6, characterized in that, the inner side of the ring top wire is also provided with a mist suction box, a return roller, a correction roller and a tension roller, along the ring top The circular rotation direction of the net, the introduction roller, the first water receiving box, the first upper forming roller, the second water receiving box, the second upper forming roller, the outlet roller, the mist suction box, the return roller, the correction roller and the tension roller are arranged in sequence The inner side of the annular top net; the outer side of the annular top net corresponding to the mist suction box is also provided with a high-pressure water spray pipe. 8. A progressive dehydration top wire former according to claim 2, characterized in that the depth of the first upper forming roller pressed into the bottom wire is 50 mm to 300 mm, and the second upper forming roll is pressed into the bottom wire The depth is 250mm-500mm; and the depth of the second upper forming roller pressed into the bottom net is 150mm-300mm deeper than the depth of the first upper forming roller pressed into the bottom net. 9. A progressive dehydration top wire former according to claim 2, characterized in that the diameter of the first lower forming roll is 1.05 to 1.2 times the diameter of the first upper forming roll, and the first upper forming roll The diameter of the second lower forming roll is 1.1 to 1.4 times the diameter of the second lower forming roll, the diameter of the second lower forming roll is 1.05 to 1.2 times the diameter of the second upper forming roll, and the diameter of the second upper forming roll is not less than 400mm.