GB2316064A

GB2316064A - Turning a web

Info

Publication number: GB2316064A
Application number: GB9715568A
Authority: GB
Inventors: Poul Holst Jespersen
Original assignee: Rockwool International AS
Current assignee: Rockwool AS
Priority date: 1996-08-13
Filing date: 1997-07-23
Publication date: 1998-02-18
Anticipated expiration: 2017-07-23
Also published as: GB2316064B; DE19734880A1; GB9715568D0; GB9617005D0

Abstract

A mineral wool web having a first face and a second face is carried with its first face uppermost in a first direction on a first conveyor transferred along a path to a second conveyor on which it is carried with its second face uppermost in a second direction. The angle between the first and second directions is from 10{ to 170{, and, which are on different levels. The moving web is guided along the transfer path by a plurality of driven guide rollers 5 which contact the outermost web face.

Description

PROCESS AND APPARATUS FOR TURNING A WEB This invention relates to processes for changing the direction of a mineral wool web, in particular a stone wool fleece, and to apparatus suitable for carrying out these processes.

In many processes for the production of man-made vitreous fibre MMVF (also known as mineral wool) it is found necessary to provide and transport a continuous web of the mineral wool material. Such webs are often carried on moving conveyors. During such processes it is often necessary to turn the web, for instance in order to accommodate the apparatus within an existing building.

In order to do this it is usual to pass the web from a first conveyor travelling in a first direction to a second conveyor travelling in a second direction. Usually the first and second conveyors are on different levels and the change in direction involves turning the web so that its underside is uppermost.

It is known to guide the moving web as it is transferred between the first and second conveyors. It is known to have some sort of guide means over which the web passes at this point, placed inside the turn of the web.

Such systems are shown for instance in W093/01115 for turning paper, US 4,155,496, US 4,343,422 and US 3,583,621, for various materials such as rubber. Similar systems having internal guide means are described in JP-A01/034,846 and US 4,716,628, the latter for transport of non-woven fabric.

In the case of a fibrous mineral wool web, however, the material can be prone to tearing, in particular in the case of a stone wool fleece. As the web is turned as it comes off the first conveyor, often at high speed, small parts of the material are liable to overshoot any internal guide used. When they reach the second conveyor they are then not synchronised with the remainder of the web, which can result in holes or other tears, and/or folds or other points of unevenness in the web as it progresses.

It would be desirable to be able to prevent such overshooting and consequent tearing. It might be expected that an external guide means of a similar type to known internal guides might be effective, for instance so that the web passes through a pair of nip rollers as it changes direction and is transferred from the first to the second conveyor. However, this in fact makes the system significantly worse than without an external guide means, and can even induce additional tearing and unevenness in the web.

According to the invention we provide a process for changing the direction of travel of a moving mineral wool web having a first face and a second face, in which the web is carried with its first face uppermost in a first direction on a first conveyor and is transferred along an upward or downward path defined externally by the outermost of the first and second faces at a point of transfer to a second conveyor on which it is carried with its second face uppermost in a second direction and the angle between the first and second directions is greater than 100 and less than 1700 and the first and second conveyors are on different levels at the point of transfer of the web and the moving web is guided along the upward or downward path between the first and second conveyors by a plurality of guide elements which each have a moving guide surface which contacts the outermost web face and wherein the direction of the velocity of the guide surface is substantially the same as the direction of the velocity of the moving outermost face.

The process can be carried out using an apparatus for changing the direction of travel of a moving mineral wool web having a first face and a second face, comprising a first conveyor arranged to carry the web with its first face uppermost in a first direction, a second conveyor arranged to carry the web with its second face uppermost in a second direction, in which the angle between the first and second directions is greater than 100 and less than 1700, the first and second conveyors being arranged so that in use the web is transferred from the first conveyor to the second conveyor along an upward or downward path defined externally by the outermost of the first and second faces at a point of transfer and such that at the point of transfer the first and second conveyors are on different levels, and in which the apparatus also comprises a plurality of guide elements, each having a guide surface and mounted for movement such that in use each guide surface contacts the outermost face such that at the point of contact with the face the direction of the velocity of each guide surface is substantially the same as the direction of the velocity of the outermost face.

The invention provides a simple and efficient system for guiding fibrous mineral wool webs as they move from one conveyor to another and change direction. In particular, the system prevents the web overshooting the first conveyor and considerably minimises resulting tears and discontinuities in the web. Further, it does this without incurring the additional problems which result from using an external nip roller.

In the invention the fibrous mineral wool web is carried on a first conveyor in a first direction. The web has a first face and a second face and as it is carried along the first conveyor its first face is uppermost. The first conveyor is usually substantially horizontal in the region of the apparatus and thus it may be truly horizontal or it may be inclined, either upwards or downwards in the direction of travel of the web. If it is inclined this is generally at an angle of from -300 to +300, usually -100 to +100.

The second conveyor is likewise usually substantially horizontal in the region of the apparatus, ie at an angle of +300, preferably +100, to the horizontal. Usually the conveyors are arranged in planes that are parallel or that are at an angle of less than 300, preferably less than 100.

Preferably both conveyors are horizontal in the region of the apparatus. If the apparatus is utilised with first or second conveyors which are inclined to the horizontal (by up to 300 or by more) along most of their length, it is usually preferred that they pass over rollers in the region of the apparatus (eg within 1 to 5 metres or more of the guide elements) that will deflect the line of travel of that conveyor from an inclined line to a horizontal or near horizontal line in the region of the apparatus.

The web is transferred at a specified point of transfer from the first conveyor to the second conveyor.

At the point of transfer the first and second conveyors are on different levels. The first conveyor may be lower than the second conveyor at this point, in which case the web travels to the second conveyor along an upward path. More usually however the first conveyor is higher than the second conveyor at the point of transfer and the web travels to the second conveyor along a downward path.

As the web is transferred from the first to the second conveyor the angle of its direction of travel is changed.

Further, the web is turned so that as it travels on the second conveyor its second face is uppermost. It will be seen then that as the web is transferred from the first to the second conveyor one face will be on the outside of the turn and the other face will be on the inside of the turn.

When the web is transferred from the first to the second conveyor along an upward path it is the second face which is the outermost face. When the web is transferred from the first to the second conveyor along a downward path, it is the first face which is the outermost face.

As the web travels along the upward or downward path defined by the outermost face, it is guided by the plurality of guide elements. Each guide element has a guide surface. The guide elements are arranged so that the guide surfaces come into contact with the outermost web face. They are also arranged so that the guide surfaces move with a velocity which is in substantially the same direction as the velocity of the portion of the outermost face of the web with which they come into contact. Thus the guide elements induce substantially reduced tearing and/or folding in the web compared to processes which are conducted without the guide surfaces.

In this specification when we say that the direction of the velocity of each guide surface is "substantially the same as" the direction of the velocity of the outermost web face, we mean that it is within 100 of exactly that direction. Preferably, it is within 50, more preferably within 20 and particularly preferably it is exactly the same. We find that adequate results can be achieved when the two directions are within 10 of each other. However, when the direction of the velocity of the guide surfaces is more than 100 different from that of the outermost web face, we find that the advantages of the invention are not achieved.

In the invention it is preferred that the guide surfaces have a speed which is the same as the speed of the outermost web face at the point of contact. Preferably the speed of the guide surfaces is from 80% to 120%, more preferably 90% to 110%, and particularly preferably substantially 100%, of the speed of the outermost web face.

The guide elements may be of any construction which provides a guide surface which moves with the required direction of velocity. The guide elements may for instance be endless belts, rotating spheres or other rotating elements. Preferably the guide elements are substantially cylindrical. When the guide elements are cylindrical each is arranged to rotate about its own longitudinal axis.

This axis is arranged to be substantially perpendicular to the direction of travel of the web as it moves along its upward or downward path. In this way the curved surface of the cylinder comes into contact with the web and has a direction of velocity substantially the same as that of the outermost face of the web.

The guide elements, if they are for instance spheres or cylinders mounted for rotation, may be freely rotating.

Preferably however they are connected to and driven by a motor which controls their speed of rotation. Similarly, if the guide elements are for instance endless belts these are also preferably driven by a motor. The motor is preferably variable so that the speed of movement of the guide surfaces can be varied. For instance it can be useful to vary the speed of all of them so as to modify the transfer of the web. More usually the speed of all of them may be adjusted in response to changes in the speed of travel of the web. Thus the web speed may vary by +10% and corresponding variation in the speed of the surfaces can be desirable.

Additionally the speed of the individual surfaces may be adjusted individually, or the speed of adjacent groups of surfaces may be adjusted as individual groups. This permits the speed of consecutive elements, or consecutive groups of elements, along the transport direction to be adjusted individually so as to reduce further the risk of tearing and pleating.

The guide elements are preferably mounted so that their positioning in relation to the conveyors is variable.

This may be necessary for instance if it is envisaged that the speed of movement of the web may be varied. For instance, if the web travels at a higher speed, it may travel further from the end of the first conveyor before it begins its upward or downward path to the second conveyor.

Preferably the guide elements are mounted so as to take this into account.

Each guide element may be driven separately.

Preferably however groups of elements are driven so as to impart the same speed of the guide surface to each. More preferably all elements are driven so that each guide surface travels at the same speed at the point of contact with the outermost face of the web.

In the invention, a single process may use a variety of different types of guide element in combination.

Preferably however at any one point of transfer all guide elements are of substantially the same shape and preferably of substantially the same size.

The web is carried in a first direction on the first conveyor and in a second direction on a second conveyor.

The angle between the two directions is greater than 100 and less than 1700. Preferably it is from 30 to 1500, more preferably from 45 to 1350. Often it is from 70 to 1100, for instance around 900.

If the angle through which the web is to be moved is known it can easily be established which is a suitable positioning for the guide elements. The exact alignment of guide elements which is required for any particular process or apparatus can be determined by experiment. It is however found that, if the angle between the first and second directions is defined as a and cylindrical rollers are used as the guide elements, they should be positioned such that their axes are positioned at an angle of (90 a/2) in relation to the plane of the second conveyor.

In the invention we require a plurality of guide elements. In some processes it is found that a small number of guide elements, for instance 2 or 3, gives adequate guiding of the web as it is transferred from the first to the second conveyor. It is preferred however that the guide elements are arranged so that most or even substantially all of the web comes into contact with a guide surface as it passes along its upward or downward path between the conveyors. Such an arrangement is particularly efficient at ensuring that all parts of the web are guided in the desired direction and minimises tearing and discontinuities in the web.

The first and second conveyors generally travel at substantially the same speed. They may be set such that the web travels at for instance 50 to 300 m/s, preferably around 120 to 180 m/s.

The invention is particularly suitable for changing the direction of a fibrous mineral wool web, which is prone to tearing and pleating. Generally the web is unbonded and the first conveyor leads from a collector where the fibres are collected by an air laying process.

The invention is of particular value for use with mineral wool webs since these are particularly susceptible to these problems. The invention is particularly suitable for the conveyance of stone wool fleece or other fleece formed from short mineral wool fibres.

The process of the invention may for instance be a process for the production of mineral wool. In the process mineral melt is formed into fibres by any suitable process for fiberising mineral melt, usually centrifugation fibre forming techniques for instance using a spinning cup type of apparatus or a cascade spinner apparatus.

The formed fibres are collected in a collecting chamber on a collecting belt, on which they form what is termed the primary fleece. Preferably it is this fleece which forms the fibrous web of the invention. The process and apparatus of the invention can be used to change the direction of the primary fleece as it is transported from the collecting chamber to devices by which it is crosslapped and compressed. The process and apparatus of the invention can also be used during the transport of any continuous web of mineral wool at any point during this process.

The process and apparatus of the invention are now illustrated below with reference to the accompanying drawings.

Figure 1 is a schematic plan view of the system of the invention.

Figure 2 is a side view looking from the direction B in Figure 1.

Figure 3 is a section along the line A-A in Figure 2.

Figure 1 shows the web 1 travelling from a first conveyor 2 in a direction x to a second, lower, conveyor 3 in a direction y. The angle a between the directions x and y is shown. The conveyor 2 leads from a collector on which short mineral fibres are collected as an unbonded web by air laying, the fibres having been formed by centrifugation of a melt on a cascade spinner. The conveyor 3 leads the web to a cross-lapper pendulum.

As the belt moves from the first conveyor to the second conveyor it is guided by a bank 4 of guide elements.

The guide elements, which are cylindrical rollers 5, are shown in Figure 2.

As the web travels from the first conveyor to the second conveyor along a downward path, its first face 12 forms the outermost face of the web as it travels along the path. It is this face 6 which is contacted by the guide surfaces 9 of the guide elements 5. Each guide element 5 is mounted on an axis 7 about which it rotates. The axes of the array of guide elements are connected and are driven by a motor (not shown).

The guide elements 5 rotate in the same direction and at the same speed such that they contact the outermost surface 6 with a velocity which has the same magnitude and direction as the velocity of the outermost face of the web.

In this manner the web is guided along its downward path 8 onto the second conveyor 3 which then carries it in the second direction y.

Claims

1. A process for changing the direction of travel of a moving mineral wool web having a first face and a second face, in which the web is carried with its first face uppermost in a first direction on a first conveyor and is transferred along an upward or downward path defined externally by the outermost of the first and second faces at a point of transfer to a second conveyor on which it is carried with its second face uppermost in a second direction and the angle between the first and second directions is greater than 100 and less than 1700 and the first and second conveyors are on different levels at the point of transfer of the web and the moving web is guided along the upward or downward path between the first and second conveyors by a plurality of guide elements which each have a moving guide surface which contacts the outermost web face and wherein the direction of the velocity of the guide surface is substantially the same as the direction of the velocity of the moving outermost face.

2. A process according to claim 1 in which the speed of each guide surface is substantially the same as the speed of the outermost face.

3. A process according to claim 1 or claim 2 in which the angle between the first and second directions is from 45" to 1350, preferably from 700 to 1100.

4. A process according to any preceding claim in which each guide element is a substantially cylindrical roller arranged such that its longitudinal axis is perpendicular to the direction of the velocity of the moving web along the upward or downward path.

5. A process according to any preceding claim in which the first and second conveyors are each substantially horizontal.

6. A process according to any preceding claim in which the web is carried on the first and second conveyors at a speed of from 50 m/s to 300 m/s.

7. A process according to any preceding claim in which substantially all of the outermost face along the upward or downward path is guided by the guide surfaces.

8. A process according to any preceding claim in which the mineral wool web is a substantially unbonded web and the first conveyor leads from a collector on which the web is formed by an air laying process.

9. A process according to any preceding claim for making mineral wool and which comprises the preliminary step of forming fibres by centrifugal fibre formation from a mineral melt and collecting the fibres as the web.