FI20185479A1 - Grooved and perforated reverse roll for a fibre web machine - Google Patents

Abstract

The invention relates to a grooved and perforated turning roll for a fiber web machine. The turning roll (12) comprises a sheath (20) and grooves (22) formed on the surface (21) of the sheath (20). In the grooves there are suction holes (23) passing through the sheath (20). The open area (AR) of a suction hole (23) is twice larger than a groove flask (22) cross-sectional area (AU).

Description

RETRACTED AND PUNCHED FIBER MACHINE SWIVEL ROLL

The invention relates to a grooved and perforated pivoting roll of a fiber web machine, which comprises a sheath and grooves formed on the surface of the sheath having suction holes extending through the sheath.

The swivel roll is also referred to as swivel suction roll, vacuum roll, or the applicant's trademark VacRoll. The swivel roller is used for the single-wire delivery of the dryer section of the fiber web machine, with a swivel roller between the two drying cylinders. A dryer wire guided through drying cylinders and rollers presses the fiber web to be manufactured against the drying cylinders. The twisting roller then has the outermost fiber web on the dryer wire without support. However, by means of a suction roll formed by a roller roller, it is possible to keep the fibrous web and, if necessary, the threaded strand cut therefrom on the drying fabric at high speeds.

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FI Patent No. 83680 discloses a cylinder used in fiber web export 20, in practice a turning roll as described above.

Here, too, there are grooves with suction holes on the surface of the swivel roll casing. A certain dimension of the grooves and suction holes has been sought to ensure a uniform grip on the fibrous web.

However, known rotating rollers have problems. In particular, the use of recycled paper as a raw material has increased the contamination of the drying section. Particularly at the beginning of the drying section, the finely divided loose material together with the sticky materials have caused the grooves and suction holes to clog. Small suction holes, in particular, become very dirty and even clogged. Square grooves also collect dirt and can also clog. Due to the large number of suction holes, large amounts of air are transferred, which increases energy consumption. In addition, turning roll manufacturing is obviously slow and slow. Despite the special size of the peripheral area, the suction effect in the head area could be better.

The object of the invention is to provide a new type of grooved and perforated pivot roll of a fiber web machine, which remains more clean and achieves a more efficient suction effect with a smaller amount of air. The features of the pivoting roller according to the invention are disclosed in the appended claim 1. In the pivoting roller 10 of the invention, the sizing of the grooves and suction holes is arranged in a new and surprising way. Firstly, clogging of suction holes and grooves is avoided. Second, the suction effect is effected effectively and evenly distributed with a smaller amount of sucked air. Cleaning the swivel roller is also easier. In addition, if necessary, the thickness of the swivel roll shell may be thinned and thus the swivel roll reduced.

The invention will now be described in detail with reference to the accompanying drawings, in which:

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Fig. 1a is a schematic drawing of a drying section of a fiber web machine with one rotating roller,

Figure Ib shows a partial magnification at one of the swivel rolls,

Figure 2a is a sectional view of the housing of the swivel roll of the invention,

Figure 2b shows a part of the surface of the sleeve of the swivel roll in accordance with the invention,

Fig. 3a is a sectional view of a swivel roll shell according to the invention,

Figure 3b is a top view of a portion of the sleeve of a swivel roll in accordance with the invention.

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Fig. 1a shows separately one drying group 10, which are several in succession in the drying section of a fiber web machine. The drying group consists of drying cylinders 11 and turning rollers 12 through which the drying wire 13 is guided as an endless loop 5. Nowadays, the use of a single-wire export as described, with only one drying wire per drying group, is increasingly used. In practice, the fibrous web passes between the drying wire and the heated drying cylinder. Correspondingly, on the swivel roll, the fibrous web passes over the dryer fabric. In addition to the pivot roll 10, the runner component 14 is used to control the fibrous web, which is placed in a pocket space 15 formed by successive drying cylinders and pivot roll (Fig. Ib). The pivoting roller has a suction connection at at least one end and the pivoting roller is absorbent from the entire circular sector.

Figure Ib also shows the opening gutter 16 defined by the drying cylinder 11 and the drying wire 13 and the closing gutter 17 formed by the drying wire 13 and the turning roll 12, respectively. tends to remove both the threading strap and the fibrous web from the surface of the drying wire 13 at the pivoting roll. Without coming into the closing gutter 17, the brochure 25 is here with a straight arrow. The grooved and perforated swivel roll provides a suction effect which, however, is substantially reduced due to clogging of suction holes and grooves.

The invention thus relates to a grooved and perforated fiber web 30 pivoting roller 12. The pivoting roller 12 includes a sheath 20 and grooves 22 formed on the surface 21 of the sheath 20. Figure 2a shows a portion of the sheath 20 viewed from the machine direction. The diaper 20 has suction holes 23 extending through the diaper 20 (Figure 3a). The vacuum created through the suction holes inside the swivel roll extends 4

20185479 prh 24-05-2018 through a cotton wire to a fibrous web. At the very least, the vacuum eliminates the overpressure caused by the closing rod. In the invention, the open area Ar of the suction hole 23 is greater than twice the cross-sectional area Au of the groove 22. The open area Ar 5 of the suction hole 23 is shown in particular in Figure 3b. In other words, the area of the suction hole is greater than the sum of the cross-sectional areas of the airflows coming from the two directions of the suction hole, i.e. the cross-sectional area of the continuous groove across the suction hole. In other words, greater than the second multiple of the Au of the groove 10 22. This ensures efficient flow in the grooves while avoiding the formation of a bottleneck in the suction hole. The area of the suction hole is determined at its narrowest point, whereby any sinking is ignored.

More specifically, the open area Ar of the suction hole 23 is 2.01 4.0, more preferably 2.8 to 3.6 times the cross sectional area Au of the groove 22. In this case, the air in the grooves can be safely removed, so that the suction effect is spread as effectively as possible. In practice, this has been achieved by changing the drilling pattern with fewer and fewer holes. In addition, the sizing and spacing of the groove has been changed. In Figure 2b, the cross-sectional area Au of the groove 22 is depicted in two lined areas. Figures 2a to 3b do not show the tissue that a production hen closes from above the groove by twisting the fibrous web by a portion of the swivel roll. Also, a smaller hole ratio than described above would probably work better. Thus, a suction hole of 1.8 to 1.99 times the groove would provide the advantages of the invention.

Further, the drilling pattern has been altered such that suction holes 23 are provided only in every other groove 22 (Fig. 2a). Surprisingly, the tests have found that air also moves sideways inside the dryer fabric. In this case, the suction effect from the perforated grooves also spreads to the unperforated grooves. Thus, by the time the seal is closed, excess air will flow from the unpunched grooves to the perforated grooves and through them into the pivot roll. The number of holes can then be reduced, thereby compensating for the known increased need for air required by larger holes. In practice, however, the new drilling pattern achieves a more uniform and higher vacuum with less airflow than before. The drilling pattern also has a phase shift of the suction holes, which further smoothes the distribution of the suction effect over the area of the pivot rolls. 2a, there is also a threading area 26 at the end of the pivoting roll, which has suction holes 23 in each groove.

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In the invention, the width L of the groove 22 is 1.0 to 1.3 times the diameter D. The width of the groove 15 can be maximized. In addition, the suction effect is effectively spread throughout the career. The cross-sectional area has been reduced by reducing the depth of the groove. Generally, the depth S of the groove 22 is 0.2 0.4 times the width L of the groove 22. In other words, the groove is clearly wider than its depth. The groove dimensioning is chosen so that two 20 times the cross-sectional area of the groove does not exceed the area of the suction hole.

Figure 3a shows in more detail the dimensioning and shaping of the groove 22. Preferably, the bottom 24 of the groove 22 has at least one radius of curvature. In this way, the groove becomes smooth without corners, thereby avoiding contamination of the groove. Similarly, cleaning a smooth groove is easy. In addition, there is a rounding 25 between the edge of the groove 22 and the surface 21 of the sheath 20. Both the smooth shape and the rounding can be done in one step, such as, for example, shaping. Thus, in one machining step, the curvature of the groove and the rounding of the edges is achieved.

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A suction hole of eight millimeters in diameter was used for testing. In addition, there were fewer suction holes. Preferably, the suction hole has a diameter of 6.5 to 10 mm. Now the 1500 mm diameter swivel roll had ten suction holes evenly spaced around the jacket circuit. Unlike usual, suction holes were made only in every other groove. In addition, the shape of the groove was shallow and gently sloping. The groove depth was 2.5 mm with a width of 9 mm. At the same time, the slot spacing and the slot width increased, resulting in an increase in the swivel roll opacity of 0.23%. However, the number of grooves decreased by 20%. With the new dimensioning, the cross-sectional area of the grooves was 20% smaller than the current one, and the combined cross-sectional area of the grooves was about half of the current one. At the same time, the suction hole was nearly twice the diameter. Surprisingly, therefore, a smaller amount of sucked air allows the fibrous web to remain well on the outside of the dryer wire, while a larger suction hole reduces losses. In practice, there were up to 70% less suction holes and up to 30% fewer grooves than the known swivel roll. This means that drilling suction holes and machining grooves takes considerably less time than before. The machining time can even be halved by machining several grooves simultaneously.

The tests showed that the swivel roller had good driveability and the threading function worked well. In addition, there was little air leakage through the grooves on the upstream side of the swivel roll. This was due, at least in part, to lower known grooves. According to the test results, the new swivel roller consumes less energy, although the suction effect is higher and the vacuum level higher.

The turntable roller according to the invention provides an improvement in the problem of fouling of grooves and suction holes. In other words, the swivel roll remains clean and suction hole clogging is avoided. At the same time, energy consumption is reduced. Turning roll production is also accelerating and raw material costs are falling. In practice, the runnability and tipping of a fiber board machine are also improved, which reduces the time required for tapping and reduces web breaks. The lower and slimmer groove, due to the reduced groove depth and notch effect, can also make the sheath thinner.

Cleaning a smooth and shallow groove is easy. A significantly larger suction hole can also be cleaned quickly. A thinner sheath accelerates drilling, reduces sheath weight and reduces material. At the same time, the depth of the suction holes is reduced, resulting in slower soiling.

As the weight of the swivel roller decreases, the drive motor can be reduced in size.

Claims (10)

A grooved and perforated pivoting roll of a fiber web machine comprising a jacket (20) and grooves (22) formed on the surface (21) of the diaper (20) having suction holes (23) extending through the diaper (20), characterized in that (23) the open area (Ar) is twice the cross-sectional area (Au) of the groove (22). 10 Swivel roll according to Claim 1, characterized in that the open area (Ar) of the suction hole (23) is from 2.01 to 4.0, more preferably from 2.8 to 3.6 times the cross sectional area (Au) of the groove (22). A swivel roll according to claim 1 or 2, 15 characterized in that the suction holes (23) are provided in every other groove (22). 4 times the width (L) of the groove (22). 4. Something claims 1-3 adequate its turning sat, known si east of that career (22) width (L) is 1.0 - 1.3 20 times the suction hole (23) diameter (D). 5. Something claims 1-4 adequate its turning 20185479 prh 24-05-2018a, characterized in that the bottom (24) of the groove (22) has at least one radius of curvature. 5a, characterized in that the suction hole (23) has a diameter (D) of 6.5 6th Swivel roll according to one of Claims 1 to 5, characterized in that there is a rounding (25) between the edge of the groove (22) and the surface (21) of the jacket (20). 30 Swivel roll according to one of Claims 1 to 6, characterized in that the groove (22) has a depth (S) of 0.2-0. Swivel roll according to one of Claims 1 to 7, characterized in that the groove (22) is shaped. The swivel assembly according to any one of claims 1-8. - 10 mm.