GB2373782A - Strip Accumulator - Google Patents

Abstract

A strip accumulator 20 for accumulating and expending strip, has a first frame 1 having one or more first rolls 3 and a second frame 2 having one or more second rolls 4. The frames face each other and are movable in relation to each other. The first frame has at least one third roll 6 and the second frame has at least one fourth roll 7. The rolls are placed before or behind the first and second rolls as seen in the direction of movement of the first and/or second frame. Preferably the third and fourth rolls are smaller than the first and second rolls. Also provided is an accumulator in which the frames move vertically (fig 3).

Description

STRIP ACCUMULATOR The invention relates to a strip accumulator for accumulating and expending strip, comprising a first frame having one or more first rolls and a second frame having one or more second rolls, the first and second frame facing each other and being movable in relation to each other.

Strip accumulators are known. For example in the steel making industry it is necessary to process a steel strip as a continuous band at a fixed velocity, for instance during pickling, galvanising or lacquering. However, the strips are supplied in coils with a certain length and must be joined to get an endless strip that can be processed. During joining, the strips must be stationary or move very slowly at the place where they are joined by for instance welding. To be able to process the steel strip at a fixed velocity while at the same time the end of the strip is joined to the next strip, a strip accumulator is placed between the site where the strips are joined and the site where the strip is processed. During joining, now the end of the strip can be stationary while the strip accumulator expends the strip, so the process can go on at a fixed velocity.

After the next strip is joined, the strip accumulator can accumulate again enough strip to be able to expend it and keep the process going at the fixed velocity while the next roll of strip is joined.

Because the steel strip is processed at high speed, and the joining of two strips takes some time, a strip accumulator must be able to accumulate a long stretch of strip. Often the strip accumulators are designed as towers, in which the upper frame can move upwards tens of metres and both frames have four or more rolls over which the strip passes from one frame to the other and back. For each combination of a first and a second roll the strip can pass two times between the frames.

For tinfoil strip having a thickness of 0.6 mm maximum, the minimum diameter of the rolls used nowadays is 350 mm. For a strip width of 1200 mm, a tower then can be easily 20 metres high and have a cross-section of 7 x 5 metres.

Often in the course of. time the continuous processes are improved and the velocity of the strip during the process is increased. This means that the capacity of the strip accumulator must be increased as well. Traditional solutions are to extend

the height of the tower or to build a second tower besides the first one. Both solutions are very expensive and take a long time to implement.

It is an object of the invention to improve the capacity of the known strip accumulator in a simple and inexpensive way.

It is an other object of the invention to provide a strip accumulator with a capacity that is higher than the capacity of the known strip accumulators, having the same dimensions.

Though the strip accumulator has been described above as being suited for steel strip, it will be understood that strip accumulators can also be used in other web handling industries, for instance the printing industry. For these strip accumulators, the same objects apply.

According to a first aspect of the invention a strip accumulator for accumulating and expending strip is given, comprising a first frame having one or more first rolls and a second frame having one or more second rolls, the first and second frame facing each other and being movable in relation to each other, in which the first frame has at least one third roll and the second frame has at least one fourth roll, the third and fourth rolls having been placed before or behind the first and second rolls as seen in the direction of movement of the first and/or second frame.

By placing extra rolls before or behind the first and second rolls the strip can make extra passes from the first to the second frame, thus giving an extra accumulating length in the strip accumulator while using little or no extra space.

According to a first preferred embodiment a third roll and a fourth roll have a diameter that is smaller than the diameters of the first and second rolls, the third and fourth roll having been placed before the first and second rolls, and the first roll with the third roll opposing the second roll with the fourth roll. For each combination of a first, second, third and fourth roll the strip can now pass four times between the frames. This embodiment can be used when the material of the strip can be guided over the third and fourth rolls with the smaller diameters without negative effects for the strip. For this embodiment, no changes have to be made in the arrangement of the first and second roll, and the only difference is that the first and second frame have to keep a greater minimum distance because of the third and fourth rolls placed between them.

According to a second preferred embodiment a third roll and a fourth roll have a diameter that is larger than the diameters of the first and second rolls, the third and fourth roll having been placed behind the first and second rolls, and the first roll with the third roll opposing the second roll with the fourth roll. Here as well, for each combination of a first, second, third and fourth roll the stnp can pass four times between the frames. However, this embodiment should be used when the diameters of the first and second rolls already have the minimum diameter that can be used for guiding the strip. According to this embodiment, rolls with a larger diameter are placed behind the first and second rolls. To be able to guide the strips over the larger rolls, the distance between the first and second rolls they belong to and the neighbouring first and second rolls must be large enough.

Still an other, third embodiment is characterised in that behind a first roll and/or a second roll two third and/or fourth rolls have been placed side by side.

Instead of one larger roll behind the first and/or second roll, as described above, it is also possible to place two rolls side by side. In this way it is for instance possible to use first, second, third and fourth rolls that have the same diameter, which can be the minimum diameter for the strip guided through the accumulator. By using rolls having the same diameter economical advantages can be reached. Here, for each combination of one first, one second, two third and two fourth rolls the strip can pass four times between the frames.

Yet an other, fourth embodiment of the strip accumulator is characterised in that behind two first rolls, placed side by side, two third rolls have been placed and in that behind each of the two opposing second rolls a fourth roll with a larger diameter has been placed. Using this embodiment, the strip can be guided first over a fourth roll, then over the combination of a first and second roll, subsequently over the two third rolls, then over the second combination of a first and second roll, and finally over the other fourth roll. The strip thus makes six passes instead of four when using the original two first and two second rolls. Because with this embodiment the strip is guided exactly symmetrical, the forces on the frames due to this embodiment will be exactly in line with the movement of the frame (s), and thus balanced. Therefore this embodiment is very suitable for the rolls in the middle of a strip accumulator.

Of course it is possible to combine two or more of the above embodiments in one strip accumulator, for instance the fourth embodiment on both sides accompanied by one or more times the second embodiment.

Preferably the strip accumulator is suited for accumulating and expanding steel strip, because especially in the steel making business it is highly desirable to improve the capacity of the strip accumulators.

According to a second aspect of the invention a strip accumulator for accumulating and expending strip is given, comprising a first frame and a second frame which are movable in relation to each other, the first frame having a roll with a small diameter in front of a roll with a larger diameter and the second frame having a roll with a small diameter in front of a roll with a larger diameter, the rolls with the small diameter being opposed to each other. With this configuration of the strip accumulator, the most simple construction for a strip accumulator is given.

As an alternative embodiment, instead of one roll with a larger diameter two rolls with a small diameter can be used. These two rolls can be placed side by side behind the small roll they belong to.

Preferably, the strip accumulator according to this second aspect of the invention is suited for accumulating and expending steel strip, just as the strip accumulator according to the first aspect of the invention.

According to a third aspect of the invention a strip accumulator for accumulating and expending steel strip is given, comprising a first frame and a second frame above the first frame, the first and/or the second frame being movable in an essentially vertical direction, the first and second frame each having two or more guide rolls with a diameter suited for guiding steel strip, wherein the first andlor the second frame has two or more rolls with a larger diameter, placed behind guide rolls, and situated symmetrical to the plane of symmetry of the strip accumulator.

This strip accumulator according to the third aspect of the invention is constructed as a so-called accumulator tower or looper tower having at least one frame moveable in the vertical direction. The steel strip that is guided by the guide rolls thus passes between the frames in almost vertical direction. By using the rolls with a larger diameter behind the guide rolls, the strip can pass twice as often between the frames, whereas only a little bit more space is needed to have enough

distance between the larger rolls. The rolls with the larger diameter are situated symmetrical to the plane of symmetry of the strip accumulator so as to keep the frames balanced and no horizontal force is exerted on the frame by the tension in the strip passing between the frames.

According to a preferred embodiment, each frame has four guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls. This already gives six or eight extra passes for the accumulator tower.

According to a further preferred embodiment, each frame has six guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls. Thus ten or twelve extra passes are possible in the accumulator tower.

According to a still further preferred embodiment, each frame has eight or ten guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls. Thus fourteen or sixteen, and even eighteen or twenty extra passes are possible in the accumulator tower.

As an alternative in the strip accumulator according to the third aspect of the invention, instead of one roll with a larger diameter two rolls with a small diameter have been used. These two rolls can be placed side by side behind the guide roll they belong to.

The invention will now be discussed referring to the accompanying drawings.

Fig. 1A shows, schematically, an embodiment of the most simple strip accumulator according to the state of the art.

Fig. IB, 1C and ID show, schematically, different embodiments of a simple strip accumulator according to the invention.

Fig. IE shows, schematically, an embodiment with a further elaboration of the invention for a simple strip accumulator.

Fig. 2 shows, in a very simplified way, an embodiment of an accumulator tower according to the state of the art.

Fig. 3 shows, in a very simplified way, an embodiment of an accumulator tower according to the invention.

The invention will first be elucidated referring to simple strip accumulators as shown in Fig. 1A tolE, and then to accumulator towers as shown in Fig. 2 and 3.

Figure lA shows a strip accumulator 10 according to the state of the art having a frame 1 with a roll 3 and a frame 2 with a roll 4. The strip 5 is guided over the rolls

3, 4 Both frames 1, 2 can be moveable or only one of them ; in Fig. 1A only frame 2 is moveable. When the frames are moved apart over a distance d, the strip accumulator accumulates a length of stnp 2d.

In a first embodiment of the strip accumulator 20 according to the invention as shown in Fig. IS two rolls 6,7 are added to the strip accumulator of Fig. 1A. These rolls 6,7 have a smaller diameter than the rolls 3,4 and are placed in front of the rolls 3,4 and face each other. To be able to do so, the frames 1, 2 have to be extended towards each other. The strip 5 now is guided over roll 1, and subsequently over the rolls 6 and 7, and then over roll 4. Upon a displacement d of frame 2, now the strip accumulator accumulates a length of strip 4d.

A second embodiment of the strip accumulator 30 as shown in Fig. 1C has two rolls 8. 9 added to the frames 1,2, which rolls 8,9 have a diameter which is larger than the diameter of the rolls 3. 4. The rolls 8,9 are placed behind the rolls 3,4. To be able to do so, the frames 1, 2 must be elongated. The strip 5 now is guided over roll 8, then over rolls 3 and 4, and subsequently over roll 9. This embodiment must be used if the rolls 3, 4 already have the smallest possible diameter for the strip that is accumulated. Here as well, upon displacement d of frame 2 the strip accumulator accumulates a length of strip 4d.

In a third embodiment of the stnp accumulator 40 as shown in Fig. ID the big rolls 8,9 are each replaced by two rolls 10, 11 which have the same diameter as the rolls 3,4. This accumulator functions in the same way as accumulator 30 according to Fig. 30. However, the use of rolls all having the same diameter can make the manufacturing of the strip accumulator cheaper. Moreover, the frames 1,2 have only to be lengthened to a limited extend.

Fig. 1E shows a further embodiment of the strip accumulator according to the invention, having both rolls 6,7 with smaller diameters and rolls 8,9 with larger diameters. Upon displacement d of frame 2 the accumulator now accumulates a length of strip 6d.

Fig. 2 schematically shows an accumulator tower 100 according to the state of the art as used in the steel industry. Shown are nine upper rolls 101, which are connected to an upper frame (not shown), and eight lower rolls 102, which are connected to a lower frame (not shown). The upper and/or the lower frame is vertically displaceable so as to accumulate or expend the strip 103. The strip passed

16 times between the frames. Movement of a frame over a distance d results thus in the accumulation or expending of a length of strip 16d.

Fig. 3 schematically shows an embodiment of an accumulator tower 110 according to the invention. Behind both six lower rolls 102 and six upper rolls 101 a roll 104 with a larger diameter has been placed. So as to have enough room to do so while maintaining a minimum distance between the strip passes, two upper rolls 101 and two lower rolls 102 have been left out as compared to accumulator tower 100, so seven upper rolls 101 and six lower rolls 102 are left. The rolls with a larger diameter 104 are placed symmetrical to the plane of symmetry of the strip accumulator, so the forces on the frames (not shown) are only vertically and not horizontally, and the frame or frames can move smoothly vertically upwards and downwards.

In Fig. 2 the diameters of the rolls is for instance 350 mm and the distance between the rolls (and strips) is 75 mm, so the total width is 3750 mm. In Fig. 3 the diameters of the rolls 104 is for instance 500 mm and the distance between the rolls (and strips) remains 75 mm, so the total width is 3800 mm. This means the dimensions of the accumulator tower as a whole have not changed, but in the accumulator tower according to Fig. 3 the strip 103 passes 24 times between the frames. Thus by removing some existing rolls 101 and 102 and adding twelve rolls 104, the capacity of the accumulator tower is increased with 50%, whereas the dimensions and further lay-out of the accumulator tower remain the same.

Though in Fig. 3 a particular embodiment for an accumulator tower has been shown, it will be clear that, making use of the invention, other configurations can be used as well The further construction of the accumulator tower, the arrangement for the movement of the frame or frames in the accumulator tower, and the way the tension in the strip is measured and controlled are not different for the accumulator tower according to the invention as compared to the accumulator tower according to the state of the art, and are thus not discussed here, as they are known to the person skilled in the art.

Claims (1)

1. CLAIMS 1. Strip accumulator for accumulating and expending strip, comprising a first frame having one or more first rolls and a second frame having one or more second rolls, the first and second frame facing each other and being movable in relation to each other, characterised in that the first frame has at least one third roll and the second frame has at least one fourth roll, the third and fourth rolls having been placed before or behind the first and second rolls as seen in the direction of movement of the first and/or second frame.

   2. Stnp accumulator according to claim 1. characterised in that a third roll and a fourth roll have a diameter that is smaller than the diameters of the first and second rolls, the third and fourth roll having been placed before the first and second rolls, and in that the first roll with the third roll opposes the second roll with the fourth roll.

   3. Strip accumulator according to claim 1, characterised in that a third roll and a fourth roll have a diameter that is larger than the diameters of the first and second rolls, the third and fourth roll having been placed behind the first and second rolls, and in that the first roll with the third roll opposes the second roll with the fourth roll.

   4. Strip accumulator according to claim 1, characterised in that behind a first roll and/or a second roll two third and/or fourth rolls have been placed side by side.

   5. Strip accumulator according to claim 1, characterised in that behind two first rolls, placed side by side, two third rolls have been placed and in that behind each of the two opposing second rolls a fourth roll with a larger diameter has been placed.

   6-Strip accumulator according to any one of the preceding claims, characterised in that the accumulator is suited for accumulating and expending steel strip.

   7. Strip accumulator for accumulating and expending strip, comprising a first frame and a second frame which are movable in relation to each other, the first frame

   having a roll with a small diameter in front of a roll with a larger diameter and the second frame having a roll with a small diameter in front of a roll with a larger diameter, the rolls with the small diameter being opposed to each other.

   8. Strip accumulator according to claim 7, characterised in that instead of one roll with a larger diameter two rolls with a small diameter have been used.

   9. Strip accumulator according to claim 7 or 8, characterised in that the accumulator is suited for accumulating and expending steel strip10. Strip accumulator for accumulating and expending steel strip, comprising a first frame and a second frame above the first frame, the first and/or the second frame being movable in an essentially vertical direction, the first and second frame each having two or more guide rolls with a diameter suited for guiding steel strip, characterised in that the first and/or the second frame has two or more rolls with a larger diameter, placed behind guide rolls, and situated symmetrical to the plane of symmetry of the strip accumulator.

   11. Strip accumulator according to claim 10, characterised in that each frame has four guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls.

   12. Strip accumulator according to claim 10 or 11, characterised in that each frame has six guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls.

   13. Strip accumulator according to claim 10 or 11, characterised in that each frame has eight guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls.

   14. Strip accumulator according to claim 10 or 11, characterised in that each frame has ten guide rolls which are accompanied by rolls with a larger diameter placed behind these guide rolls. 15. Strip accumulator according to any one of the claims 10 to 14, characterised in that instead of one roll with a larger diameter two rolls with a small diameter have been used.

   16. Strip accumulator substantially as any one embodiment herein described with reference to the accompanying figures.