WO1992022507A1

WO1992022507A1 - Apparatus used in production of fibres

Info

Publication number: WO1992022507A1
Application number: PCT/FI1992/000186
Authority: WO
Inventors: Matti Unkuri
Original assignee: Paroc Oy Ab
Priority date: 1991-06-19
Filing date: 1992-06-15
Publication date: 1992-12-23
Also published as: FI88018B; FI913000A0; FI88018C

Abstract

The invention comprises a device for the production of fibres for forming into mineral-fibre matting, which device consists of a wool chamber (1), one open end of which is directed towards a fibration device (7) and the other open end of which is directed towards a conveyor (3) for the collection of fibres produced in the fibration device (7). The wool chamber (1) has an envelope surface in the form of a rotation body with essentially a horizontal axis of rotation, and preferably a rectilinear or arc-shaped generatrix and is arranged so as to be capable of being rotated with a cleaning device arranged against the inner wall of the wool chamber.

Description

Apparatus used in production of fibres

The invention consists of a device for the production of fibres for forming into mineral-fibre matting, which device consists of a wool chamber, one open end of which is direc¬ ted towards a fibration device and the other open end of which is directed towards a conveyor for the collection of fibres produced in the fibration device.

Mineral wool products are manufactured by a process, for example, in which the required raw material is melted in a melting furnace and the molten mineral material is then taken continuously from the furnace via a discharge opening and is transformed into fibres via a fibration device. The fibration device may, for example, consist of a number of rotating wheels, from which the molten mineral is propelled to form fibres. The fibres formed in this way are conveyed from the fibration device by a stream of air in a wool chamber to a collecting conveyor, forming a fibre web. The fibres may be collected in such a way that a web of the desired, final thickness is already formed at this stage, or in such a way that a "primary web" is first formed, consisting of a thin layer of fibres, which layer is folded at a later stage of the process into a secondary web of the desired thickness. The collecting conveyor may consist of one or more perforated conveyor belts, apron conveyors or drums.

The air current in the wool chamber is produced partly by blowing air in via the fibration device towards the col¬ lecting conveyor, and partly by arranging extraction from the rear end of the collecting conveyor. However, this air current, with the aerodynamically unsatisfactory design of prior art wool chambers, incorporating angles and corners, creates undesirable turbulence, leading to uneven fibre deposits on the conveyor, and the formation of fibre aggre¬ gates. The fibre aggregates formed show a tendency to stick and form deposits on the inner walls of the wool chamber, which are difficult to clean. In addition, it is undesir¬ able that the mineral fibre web produced should contain mineral fibre aggregates of this kind, since these are detrimental to the characteristics of the final product. Apart from the mineral fibre aggregates, it is also desir¬ able for the larger particles formed in the fibration device, known as "pearls", to be separated in an efficient way from the fibres. Separation may be achieved, for example, by arranging for the fibre stream to be directed against a threshold plate, as a result of which the direc¬ tion of the fibre stream is altered, at which point some of the pearls are separated and fall down a waste shaft. However, because of the fairly strong air current, some of the pearls will be carried along and will thus accompany the fibre stream into the collecting conveyor. This con¬ tributes to the formation of an uneven product on the collecting conveyor.

In the wool chamber, a hot-setting binding agent is suitab¬ ly introduced into the fibre stream, as well as other additives, to make the fibres stick together into a fibre web. This binding agent increases the tendency towards aggregate formation, and thus of deposits on the inner walls of the wool chamber.

In FI Patent Document 60 384, a method for obtaining a flock-free stream of fibre, in an essentially turbulence- free wool chamber is proposed. This is achieved in an essentially horizontal wool chamber with a rectangular cross-section, in which two of the walls are vertical and the cross-section of the wool chamber diminishes between the inlet end and outlet end. By using a diminishing cross- section in the direction of the collecting conveyor, an acceleration of the airflow, and therefore of the fibre stream between inlet and outlet end, is produced, leading to a reduction in flocculation. It is also stated that the inlet aperture should be as open as possible to minimize turbulence.

In ^' FI Patent Document 78 445, a method for keeping clean the inner surfaces of wool chambers is proposed. The method consists of using a double structure for the walls of the wool chamber and perforating the inner surfaces. Inside the double structure, suction is used to hold a heat-resistant loose lining against the inner wall. When the lining has been coated with so much mineral wool that it has to be cleaned, the production process is halted. The suction in the double wall is then switched off, releasing the heat- resistant loose lining, which may then be replaced by a new clean loose lining.

In GB Patent Document 1 227 032, a device is described in which air is blown into the part of the wool chamber in which fibration takes place and in which, in addition, air is extracted via the perforated collecting conveyor. The air is extracted via the perforated surface of the collect¬ ing conveyor by means of several independently adjustable extractor devices arranged along the surface of the col¬ lecting conveyor. The air to the wool chamber is introduced via a perforated disc. This arrangement allows an even air current in the end section of the wool chamber and along the whole perforated surface of the collecting conveyor. The lower section of the wool chamber contains rollers, below which a funnel-shaped collecting chamber with a conveying screw at the bottom is arranged.

According to the invention, the problems of turbulence and the depositing of fibres on the internal surfaces of the wool chamber are solved in that the wool chamber has a housing in the form of a rotation body with essentially a horizontal axis of rotation. The generatrix of the rotation body is preferably rectilinear or bow-shaped, i.e. bowed along the whole or part of its length. The wool chamber, being formed as a casing, therefore has an opening at either end, one directed towards the fibration device and the other, at the opposite end, towards the fibre collect¬ ing conveyor, its envelope surface being in the form of a rotation body, i.e. the form that is described by the generatrix of the rotation body as it makes a revolution around its essentially horizontal axis (axis of rotation) . The said axis of rotation constitutes in this design the essentially horizontal axis of symmetry for the wool cham- ber, and is referred to in brief in the following text as the axis of symmetry, or axis. Thus, each cross-sectional area of the wool chamber that is perpendicular to the axis of symmetry is circular, which is aerodynamically advan¬ tageous and contributes substantially to reducing turbu- lence in the wool chamber. This effect may be further enhanced by designing the envelope surface in the form of a rotation body whose generatrix is either rectilinear or bowed along the whole or part of its length, and does not contain any angles, as a result of which the envelope surface displays neither sharp sections nor corners. Accor¬ ding to the invention, this allows a more even structure for the matting to be obtained on the conveyor, while the tendency for coatings to form on the inner walls of the chamber is at the same time reduced, and thus the need for cleaning. The axis of symmetry is essentially horizontal, meaning that the axis forms an angle of at most 30° to the horizontal plane. In addition, the wool chamber is arranged to be capable of being rotated around its intended axis of symmetry.

To allow simple cleaning of the side walls of the wool chamber, cleaning which does not require a production shut¬ down, the wool chamber is also equipped, in an advantageous embodiment of the invention, with devices fitted in contact with the inner wall of the wool chamber to clean the wool chamber during rotation of the same. These devices are fitted in the lower part of the wool chamber, i.e. below the horizontal plan through the axis. In this arrangement, the cleaning devices are fixed-position, i.e. stationary, relative to the direction of rotation of the wool chamber. These cleaning devices allow the process to operate con¬ tinuously, without any need to halt the process for clean¬ ing of the wool chamber. The wool chamber may be arranged to rotate continuously during production, e.g. at a speed of about 1 revolution per minute, or it may be set to rotate when required, e.g. at pre-deter ined intervals.

The cleaning devices may be such that they operate in contact with the inner wall, e.g. scraper blades, worm conveyors or rotating brushes. According to a preferred embodiment, it is possible to use two intermeshing worm conveyors, which are thus able to clean each other. The coating that is loosened by the cleaning devices during rotation of the wool chamber is then discharged by a suit¬ able process from the lower section of the wool chamber.

In an advantageous embodiment, the cross-sectional area of the wool chamber varies in an axial direction, and is suitably designed in the form of a cone frustum, the base of which is directed towards the collecting conveyor. The cross-section of the top of the cone is suitably adapted, with regard to the fibration device and volumes of expelled air, so that as small a proportion as possible of the pearls are carried by the stream of air into the wool chamber without significantly limiting the intake of fibres into the cone. As air is extracted from the base of the cone via ,,the perforated collecting conveyor at the same time as air is blown into the top of the cone and the cone frustum expands towards the collecting conveyor, an essen¬ tially turbulence-free stream of air through the wool chamber is obtained. As a result, a very even deposit of fibres on the collecting conveyor is achieved, and only a small proportion of the fibres become attached to the inner wall of the wool chamber. According to another embodiment, the envelope surface of the wool chamber takes the form of a rotation body with an arc-shaped generatrix bowed in a direction towards the axis of rotation. In this design, the wool chamber takes a venturi- or ejector-form, with the smallest cross-sectional area at a distance from one open end of the wool chamber, preferably between the two open ends of the wool chamber. In a further embodiment, the wool chamber may be cylindri¬ cal. From the viewpoint of production technology, this is more advantageous, but is not as efficient in use as the wool chamber with a varying cross-sectional area.

The other characteristics of the invention are evident from the attached Patent Claims. An advantageous, but not restrictive, embodiment of the invention is described in the following, with reference to the attached drawing, in which

Figure 1 shows a side elevation of a cross-section of a wool chamber design in which the collecting con¬ veyor is made up of an endless perforated con¬ veyor belt.

Wool chamber 1 in this embodiment takes the form of a cone frustum, with its base directed towards collecting conveyor 3. As a continuation of the rotating cone frustum from the base to collecting conveyor 3, a suitably shaped, station¬ ary protective piece, or hood 2, is arranged to direct the stream of air from the cone towards collecting conveyor 3 and to prevent leakage of air prior to collecting conveyor 3. The collecting conveyor 3 may be made up of an endless perforated belt, a drum or an apron conveyor. In addition, wool chamber 1 is arranged to rotate around its axis of symmetry. This rotation may be suitably obtained via the outer casing of the cone 1, with the aid of a suitable driving device 4. In the part of the wool chamber 1 that is below the hori¬ zontal axis, a worm conveyor 5, placed in contact with the inner wall of wool chamber 1, is arranged for cleaning of this item during rotation of wool chamber 1. Worm conveyor 5 is stationary, relative to the direction of rotation of wool chamber 1. As wool chamber 1 and worm conveyor 5 rotate, the inner walls of wool chamber 1 are cleaned, and the material loosened is conveyed by worm conveyor 5 to a waste chamber 6 for discharge from the process.

As an alternative to a worm conveyor, cleaning may also be performed simply using a rotating brush, preferably of a screw-type design, or a scraper blade or scraper conveyor in contact with the inner wall, suitably set at an angle to the line of the axis of the cone, to achieve maximum efficiency in the discharge of the coating removed. In the event that the cross-sectional areas of the wool chamber varies, e.g. is venturi-form, cleaning is arranged by the use of a scraper conveyor operating over the surface in line with the axis of the chamber.

Rotating wheels 8 of fibration device 7 are arranged in the vicinity of the top of the cone-shaped wool chamber 1, in which it is preferable for the angle of the opening on the cone to be located in contact with the spinning device, to maximize efficiency of pearl separation. When the molten material runs down over the housing of the rotating wheels 8, it is propelled by the latter, thinning out to form fibres. A stream of air deflects the fibres into wool chamber 1, and then to collecting conveyor 2. Part of the material, i.e. that which forms pearls, is due to its weight propelled essentially in a vertical direction from rotating wheels 8, and never enters wool chamber 1. These pearls come into contact with suitable deflection devices 9 and conveyors 10, by which they are removed from the process. In the illustrated embodiment, a wool chamber is used for a single fibration device 7, but it is equally possible within the scope of the invention to arrange a shared wool chamber to serve a number of fibration devices. It is also possible to design the installation to consist of a number of adjacent wool chambers, with one wool chamber for each fibration unit or device.

Conveying of the gas- or air-borne fibre stream from fibra- tion device 7 via wool chamber 1 to collecting conveyor 3 is such that gas or air is introduced via the top of the cone essentially in a direction along the axis of symmetry of the wool chamber, and is extracted via the perforated collecting conveyor 3. To obtain an evenly distributed web of fibre material, directed blowing from the fibration device is used in many cases.

Claims

Claims;

1. Device for the production of fibres for forming into mineral-fibre matting, which device consists of a wool chamber (1) , one open end of which is directed towards a fibration device (7) and the other open end of which is directed towards a conveyor (3) for the collection of fibres produced in the fibration device (7) , characterized in that the wool chamber (1) has an envelope surface in the form of a rotation body with essentially a horizontal axis of rotation, and that the wool chamber (1) is arranged to be capable of being rotated around its axis of symmetry.

2. Device according to claim 1, characterized in that the rotation body has a rectilinear generatrix.

3. Device according to claim 2, characterized in that the wool chamber (1) takes the form of a cone frustum, the base of which is directed towards the collecting conveyor (3) .

4. Device according to claim 1, characterized in that the rotation body has an arc-shaped generatrix.

5. Device according to claim 4, characterized in that the smallest cross-sectional surface perpendicular to the axis of symmetry of the wool chamber, is located between the two end apertures of the wool chamber.

6. Device according to any of claims 1 - 5, characterized in that WQOI chamber 1 incorporates devices (5) on the part located below the horizontal plane, via the axis of symme¬ try, which devices are fitted in contact with the inner wall of the wool chamber (1) to clean the latter during rotation of the wool chamber (1) .

7. Device according to claim 6, characterized in that the cleaning devices (5) are stationary relative to the direc- tion of rotation of the wool chamber.

8. Device according to claims 6 or 7, characterized in that the cleaning devices are made up of worm conveyors, scraper conveyors or rotating brushes.