EP4082952A1

EP4082952A1 - Guide for a threading tape in a pulp dryer

Info

Publication number: EP4082952A1
Application number: EP21170627.0A
Authority: EP
Inventors: Lauri KALLIO; Juha-Pekka Kisonen; Esko Similä
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2022-11-02
Also published as: CN115247951A

Abstract

The invention relates a guide for a threading tape in a pulp dryer. The guide (18) includes a rotatably supported wheel (19) on an axle (20) and a bracket (21) supporting the axle (20) and to be attached to the pulp dryer. The bracket (21) includes two joint points (22, 23) for different directions (24, 25) each one of which having adjustment means (26, 27) of their own.

Description

The invention relates to a guide for a threading tape in a pulp dryer, the guide including a rotatably supported wheel on an axle and a bracket supporting the axle and to be attached to the pulp dryer.
Finnish patent number 110531 discloses a device for feeding a threading tail into a tape for threading tail. The threading tail of the pulp web is passed through the dryer by means of a tape. The tape is an endless narrow belt running through the dryer. The belt is a fabric made of jute or aramid for example. The tape has two parts seamed together from one side. In this way, the parts can be opened, and the threading tail can be put between the parts. The threading tail is fed into the opened tape and then the tape is closed again. The closed tape keeps the threading tail in the grasp and leads the threading tail through the pulp dryer. After the pulp dryer the tape is opened, and the threading tail is released and dumped into the pulper.
The tape is narrow, but about 1000 to 1500 meters long and it is supported with several guides. The tape is quite heavy with two parts and the tape pulls the threading tail through the pulp dryer. Thus, the guides need to withstand pulling but also has to keep the tape under control. The guide includes a rotating wheel or equivalent.
There are many problems with the known technology. The guides are difficult to adjust. The run of the guide cannot be adjusted while the tape is running. In practice, the tape must always be stopped completely, and the tension of the tape is also released before the adjustment. Thus, the adjustment is laborious and time consuming. In many times, the adjustment is often done poorly. But poorly adjusted tape causes many problems such as threading problems, threading tail breaks, tape damage and other equipment damage. At the same time there occurs delays in tail threading and the safety issues. The guides contain a lot of specially made parts making production slow and expensive. Also, the existing parts, especially the brackets of the guides are large, heavy, and clumsy. The bracket is attached to the machine frame with bolts. When these bolts are opened, the structure of the bracket falls apart making the adjustment really difficult.
It is an object of the invention to provide a novel guide for a threading tape in a pulp dryer, which guide being easier and faster to adjust than before. The characteristic features of the guide according to this invention are stated in the accompanying Claims. There can be many adjustment directions each one of which can be adjusted independently. Also, the adjustment can be done while the threading tape is under tension and running. Surprisingly, the adjustments can be done with adjustment means that hold against the forces from tape tension and running while enabling precise and fast adjustments.
The invention is described below in detail by referring to the enclosed drawings which illustrate some of the embodiments of the invention, in which

Figure 1: shows a simple side view of a pulp dryer,
Figure 2a: shows one embodiment of the guide according to the invention in cross section,
Figure 2b: shows one part of the embodiment of Figure 2a,
Figure 3: shows another embodiment of the guide according to the invention in perspective.

Figure 1 shows a pulp dryer 10 including several drying levels arranged on top of each other. Each drying level includes two rows of blow boxes with their nozzle surfaces directed towards each other. When starting the production, a narrow threading tail is cut from the pulp web. The pulp web can be cut with a waterjet cutter before the press section. During the tail threading, the pulp web is run down for pulping. The tail threading is an important and critical event in the startup of the pulp dryer. Failure in the tail threading causes production losses and extra work.
In Figure 1, only the turning rolls 13 are shown with one blower tower 11. In practice, there are several blower towers, which supply air to the blow boxes hovering the pulp web (not shown). The righthanded stack of the turning rolls 13 has a common drive at the bottom of the pulp dryer. The drying levels with the turning rolls are inside a hood 14. Here, the loop of the endless threading tape 15 is also shown. The threading tape runs the same route via the turning rolls as the pulp web during drying. But in the beginning, with several guides the threading tape is first opened, and the threading tail is fed with suitable device or even by hand inside the threading tape. The threading tape closes before the next guide thereby pulling the threading tail inside the hood at the topmost drying level. The threading tape with the threading tail runs through the other drying levels to the lower part of the pulp dryer. At the end, the pulp dryer includes a pull nip 16. After the pull roll 17 of the pull nip 16, the threading tape 15 returns back forming a closed tape loop while the threading tail continues further (not shown). When the threading tail has proceeded over the first turning roll to the second drying level, the waterjet cutter starts to move sideways. Thus, the threading tail is finally spread out full wide.
As shown in Figure 1, in addition to the turning rolls, the passage of the threading tape is controlled by dozens of different guides, for example pulleys, folding wheels and tape wheels. In general, the guide is for a threading tape in a pulp dryer. Basically, the guides are outside of the hood. Two embodiments of the guide according to the invention are shown in Figures 2a and 3. In general, the guide 18 includes a wheel 19 which is rotatably supported. In other words, the wheel rotates when the threading tape runs. The wheel is supported on an axle 20. Further, the guide 18 also includes a bracket 21 supporting the axle 20. The bracket is attached on the pulp dryer. There may be also auxiliary supports for attaching each bracket to the pulp dryer. According to the invention, the bracket 21 includes two joint points 22 and 23 for different directions 24 and 25 each one of which having adjustment means 26 and 27 respectively of their own. In this way, each direction can be adjusted independently. In practice, even with two direction the most of adjustments can be handled if the guide and its bracket is well positioned at the beginning. Small adjustments are needed, for example when the properties of the threading tape change during its lifetime. With the adjustment means, this fine tuning is quick, easy and accurate. Adjustment is also needed if the pulp web hits the wheel during a web broke. Then the alignment of the wheel may change if the supports bend.
Usually, the threading tape wraps the wheel at least 45 degrees, more commonly over 90 degrees. Then with two directions 24 and 25 perpendicular to each other the threading tape can be handled perfectly. It is also easier to choose in which direction the wheel should be turned. Advantageously, the directions 24 and 25 intersect. In this way, the turnings will change the position of the wheel as little as possible.
This keeps tuning accurate and subtly. At the same time, the forces stressing the bracket keep as little as possible. Also, the geometric features are easy to implement in practice with simple and robust structures.
According to the invention, the adjustment means 26 and 27 are backlashless. Thus, any harmful vibration is avoided, and adjustment is possible when the threading tape is crawling. In the shown embodiments, the adjustment means includes one or more screws. Also, other spirals or threads may be utilized. With these means, the adjustments are also stepless. Advantageously, the adjustment means 26 and 27 has locking means 28 and 29 of their own. In this way, each direction can be adjusted independently. Also, when the tuning is correct, the position can be securely stayed. Next time when the tuning is needed, the locking means are loosened, and adjustment means operated. And finally, advantageously the adjustment means 26 and 27 and locking means 28 and 29 are combined or in other way integrated. This makes the structure simple, and it is easy to use with standard tools. Also, any loose parts can be avoided.
Figure 2a shows one embodiment of the guide according to the invention. Here, the bracket 21 is arranged only on one side of the wheel 19. In this way, it is easy to attach the guide to the pulp dryer. Also, the threading tail can travel without hindrance. Here, the wheel 19 is hollow and the joint points 22 and 23 are arranged inside the circumference of the wheel 19. In this way, the position of the wheel changes as little as possible when the wheel is turned in relation of either direction. At the same time, the forces against the bracket will stay reasonable. And more, the hollow wheel is light weighted, which helps the assembly.
In Figure 2a, the bracket 21 includes a block 30 having a round hole. The hole is for a pin 31 with a flange 32. The pin is attached via the flange 32 to the pulp dryer or an auxiliary support, and the block is attached to the pin. The block 30 and thereby the whole bracket 21 with the wheel 19 can be adjust both axially and radially in relation to the pin 31. After positioning, the block is secured to the pin. If needed, the guide is afterwards adjusted via the adjustment means according to the invention.
The block 30 has two arms 33, one at each side of the block 30. The arms 33 are thus at the distance from each other forming a fork. At the inner end of the arms there is the first joint point 22. In relation to this joint point 22, the wheel 19 is tilted as shown with dashed lines. To the joint point 22 between the arms is attached a shoulder pin 34 the upper end of which is connected to the outer end of the arms 33 via the first adjustment means 26. Here the adjustment means 26 consists of a turnbuckle 35. In both end there is an eye having an inner thread. Between the eyes there is a rod 36 with corresponding two-handed outer thread. In the middle of the rod 36 there is a key point 37. Here the first locking means 28 consist of a nut 38 on the rod 36. First the nut is loosened from the eye. Then the rod 36 is rotated with a hand tool and thereby the shoulder pin 34 and the wheel 19 are tilted. The key point can be reached even the wheel rotates. After adjustment, the nut is tightened again.
Figure 2b shows a pivot 39 which is turnable attached on the shoulder pin 34. The pivot 39 also includes the axle 20. More general, the axle 20 is attached to the bracket 21 and there is a bearing 40 between the axle 20 and the wheel 19. In other words, the axle is stationary. Here the bearing 40 includes two standard ball or roll bearings. Like the arms, the shoulder pin 34 is equipped with two lugs 41. The pivot 39 has a leg 42 situated between the lugs 41 like the turnbuckle. In addition, the second adjustment means 27 are arranged between the lug 41 and the leg 42. Then by urging the leg with the adjustment means the pivot and thereby the wheel are turned. Here also, the adjustment means consist of an inner screw 43 with a locking nut 44. Advantageously, there are two opposite screws on both side of the leg.
Figure 3 shows another embodiment of the guide according to the invention. Here also, the wheel 19 is supported on the axle 20 with a bearing 40. In practice, there are one bearing on both ends of the wheel. This this embodiment, the axle is supported by two articulated bearings 45 and 46 arranged axially apart. In addition, each articulated bearing has a latitude restricted by corresponding adjustment means 26 and 27. Here, the outer articulated bearing 45 moves sideways while the inner articulated bearing 46 moves up and down. The actual turning point of the wheel is outside of the wheel, but the wheel is small, and it has small wrap of the threading tape. Thus, the forces are small.
Basically, both articulated bearings have the same structure, but they have an angle difference of 90 degrees. Here, the adjustment means include an adjustment screw 47 on one or both sides of the articulated bearing. For clarity, only one adjustment screw 47 is shown. Advantageously, there is another adjustment screw on the opposite side. Also, the adjustment screw 47 has a nut 48 for locking like in the first embodiment. Here, there is an intermediate sleeve 49 between articulated bearings. The sleeve with the articulated bearings forms the bracket which is attached to the pulp dryer.
The wheel of the guide according to the invention is supported only on one side. In other words, the bracket is needed only on one side. Nevertheless, the wheel is easily adjustable especially in two directions. As described earlier, the bracket has two basic adjustments. Also, both adjustment ranges are significantly larger than before. In the embodiment of Figure 2a, the maximum tilting angle in the direction 24 of the threading tape is 36 degrees. More generally, the tilting angle is 20 - 45 degrees. This range is from one end to another. Secondly, in the Figure 2a, the maximum turning angle is 26 degrees in the other direction 25. More generally, the turning angle is 10 - 35 degrees. By the new adjustment means, these angles can be changed steplessly and independently from each other. Easier adjustment and better usability are repeated for the entire cycle of the threading tape. Also the ranges are bigger than before. Thus, the auxiliary supports do not have to be made as a tailor made, and one guide fits in various different positions.
Also, the bracket allows transverse adjustment in relation to the machine direction. This possibility is realized with all guides unlike before. The same fastening way also makes it possible to turn the entire structure so that the angle adjustments are always made in accordance with the direction of travel of the threading tape.
Joint points for angle adjustments are near the center of the wheel. In other words, the joint points are inside the circumference of the wheel. This also allows adjustment when the threading tape is running and tight. Also, the weight of the new hollow wheel is about one third of the known wheel. This allows more simpler auxiliary brackets.
Figure 3 shows a small wheel with unique adjustment mechanism. More precisely, the adjustment means are implemented with articulated bearings tucked inside the bracket. Here, the maximum adjustment range in each direction is about 10 - 20 degrees. Again, the adjustment means made screws also allows angle adjustments with the tight threading tape in two directions.
In both embodiments, good adjustments in a small package are achieved. Simultaneously, both brackets are much easier to adjust than before and also the acquisition costs will be reduced as the parts are reduced and lightened. In practice, the adjustments can be done independently and when the threading tape is crawling. This accelerates the adjustment work significantly when the effect of adjustment can be seen in real time. At the same time, occupational safety and usability are improved. While the adjustment will be done better and the brackets are is easier to adjust, the equipment breakages and needs for repair are reduced significantly.

Claims

Guide for a threading tape in a pulp dryer, the guide (18) including a rotatably supported wheel (19) on an axle (20) and a bracket (21) supporting the axle (20) and to be attached to the pulp dryer, characterized in that the bracket (21) includes two joint points (22, 23) for different directions (24, 25) each one of which having adjustment means (26, 27) of their own.
Guide according to claim 1, characterized in that the directions (24, 25) are perpendicular to each other.
Guide according to claim 1 or 2, characterized in that the directions (24, 25) intersect.
Guide according to any of claims 1 - 3, characterized in that the adjustment means (26, 27) are backlashless.
Guide according to any of claims 1 - 4, characterized in that the adjustment means (26, 27) has locking means (28, 29) of their own.
Guide according to claim 5, characterized in that the adjustment means (26, 27) and locking means (28, 29) are combined.
Guide according to any of claims 1 - 6, characterized in that the bracket (21) is arranged only on one side of the wheel (19).
Guide according to any of claims 1 - 7, characterized in that the wheel (19) is hollow and the joint points (22, 23) are arranged inside the circumference of the wheel (19).
Guide according to any of claims 1 - 8, characterized in that, characterized in that the axle (20) is attached to the bracket (21) and there is a bearing (40) between the axle (20) and the wheel (19).
Guide according to any of claims 1 - 9, characterized in that, characterized in that the adjustment means (26, 27) are stepless.
Guide according to any of claims 1 - 10, characterized in that, characterized in that the adjustment means (26, 27) are independent form each other.
Guide according to any of claims 1 - 11, characterized in that in the direction (24) the tilting angle is 20 - 45 degrees.
Guide according to claim 1 - 12, characterized in that, characterized in that in the other direction (25) the turning angle is 10 - 35 degrees.
Guide according to any of claims 1 - 11, characterized in that, characterized in that the adjustments means (26, 27) includes two articulated bearing (45, 46) arranged axially apart and each has a latitude restricted by corresponding adjustment means (26, 27).
Guide according to claim 14, characterized in that, characterized in that maximum adjustment range of the articulated bearing (45, 46) in each direction (24, 25) is about 10 - 20 degrees.