GB2319249A - Apparatus for the production of man-made vitreous fibres - Google Patents

Abstract

The set (1) of rotor units (54) of a centrifugal cascade spinner for forming MMV fibres are mounted within a duct which is defined by a substantially tubular wall (8), at least two of the rotor units are supported by an individual driven support (47) which extends between the duct wall (8) and the rotor (43, 44, 45 or 46), and there is a drive (49) for moving that rotor independent of the other rotors with a movement which has independently selected vertical and horizontal components and/or which has independently selected pivoting about a substantial vertical axis.

Description

Processes and Apparatus for the Production of Nan-Made Vitreous Fibre Products This invention relates to apparatus and processes for making man-made vitreous fibre (MMVF) products by a centrifugal cascade spinner technique.

A centrifugal spinner comprises a first rotor and one or more subsequent rotors each mounted for rotation about a substantially horizontal axis and arranged such that melt poured on to the first rotor is thrown on to the or each subsequent rotor in turn and is thrown centrifugally off the or each subsequent rotor and optionally off the first rotor as fibres.

A conventional centrifugal cascade spinner is bulky and of irregular shape and has motors offset from the rotors, for instance as illustrated in US 5131935 and W092/06047. As shown in those publications, it is conventional to provide air blasts to promote formation of fibres and to transport the fibres away from the rotor.

For instance often the rotors are mounted on a bulky solid housing having a front face which contains slots around part or all of the periphery of one or more of the rotors to allow an air blast along the or each rotor as a wall jet. The housing may additionally include other openings for secondary air streams for transporting the fibres away from the rotors.

In WO 88/06146 a rotor unit is shown which comprises a single rotor mounted in a relatively streamlined housing that supports the rotor at one end of the housing and includes a motor coaxial with the rotor for driving the motor. No details are given about how such a single unit should be utilised in practice to form fibres, or about the relationship between air that is forced internally of the housing and any air that may flow around the housing.

In WO 93/13025 a cascade spinner discharges towards a steeply inclined collector surface and a primary air blast and a plurality of other air blasts are provided through and around the spinner. No relevant details are given about the rotors.

Fibre formation, and the properties of the final product, are greatly influenced by the spatial relationship between the individual rotors in the cascade spinner. For instance tilting the entire cascade spinner through a few degrees about its substantially horizontal axis so as to alter the angular disposition of the rotors relative to one another can alter the fiberising performance of these rotors. For instance this may be desirable as a response to a change in melt properties. Such apparatus is described in U.S. 3,159,475 and in W092/10436, which also describes movement of individual rotors.

In US 2398707 melt is fed to the nip of a pair of fiberising rotors and the size of the nip is adjusted by mounting the two rotors from a support above the rotors on two arms each of which can be rotated a small angle about the support so as to adjust the nip. Accordingly this can result in a movement which has a predetermined combination of vertical and horizontal components. In US 2428810 melt is poured onto a first rotor and thrown onto a subsequent rotor and the supports for the rotors are designed to allow angular movement between the axes of the two rotors. In US 2520169 a cascade spinner comprises a first rotor and three subsequent rotors, optionally at selected axially angular positions, and the mounting for the rotors is yieldable to allow the rotors to move apart if a solid chunk of slag or fuel falls between.

In our unpublished application PCT/EP96/02068 and its British priority document GB 9509782.0, we have described a rather different type of cascade spinner apparatus. The apparatus comprises a duct which is defined by substantially tubular wall and which is open at its front end, and a cascade spinner mounted within the duct. The cascade spinner can comprise a set of rotor units each consisting of a rotor mounted for rotation about a substantially horizontal axis substantially in the front end of the duct and a substantially coaxial drive motor behind the rotor. There are arms or other support means for supporting the set of rotor units from the wall of the duct. The entire set can be oscillated relative to the duct through a small angle about a substantially vertical axis. The entire set can be pivoted about a substantially horizontal axis which is substantially parallel to the axes of rotation of the rotors or about a substantially horizontal axis which is substantially perpendicular to the axis of rotation of the rotors.

Although the apparatus described in PCT/EP96/02068 does allow for a much greater degree of optimisation of the melt flow and air flow conditions than can easily be obtained by conventional cascade spinners, it would be desirable to allow for even greater optimisation According to the invention, apparatus for forming MMV fibres comprises a duct defined by a substantially tubular wall and which is open at its front end, a set of rotor units mounted within the duct each consisting of a rotor mounted for rotation about a substantially horizontal axis substantially in the front end of the duct and a substantially coaxial drive motor behind the rotor, wherein the set of rotor units consists of a first rotor unit and at least one subsequent rotor unit whereby melt poured onto the first rotor is thrown onto the or each subsequent rotor in sequence and is thrown off the or each subsequent rotor and optionally off the first rotor as fibres, and support means for supporting the set of rotor units from the duct wall, and in the invention the support means comprise individual driven supports for at least two of the rotor units whereby each individual driven support extends between the duct wall and the rotor which is supported by that support and the support means includes a drive for moving that rotor independent of the other rotors with a movement which has independently selected vertical and horizontal components and/or which has independently selected pivoting about a vertical axis. This movement is usually within a radial plane.

By referring to a radial plane, we mean a plane which is perpendicular to the axis of the duct. The plane may be in the duct or slightly in front of the front end of the duct. Often the plane, and the rotors, are slightly in front of the duct. The rotors are advantageously in front of the duct in order to minimise fouling of the duct by melt or fibres, but should be sufficiently close to the duct that the flow of air over the rotors is strongly influenced by the duct.

Usually all the rotor units are provided with the described individual supports so that each rotor unit can be moved independently of all the rotors into independently selected horizontal and vertical positions, generally all in the same radial plane. However it can be adequate for one of the rotors (in a set of three or four) or sometimes even two of the rotors in a set of four to be mounted on support means which does not allow for such movement. For instance the support may be fixed and hold that rotor in a fixed position or the support for that rotor may only allow movement of the rotor in one direction or in a predetermined combination of horizontal and vertical components.

The drive additionally or alternatively may provide angular movement of the axis of that rotor relative to the axis of the duct by pivoting the rotor about a substantially vertical axis. The pivoting may be occasional or it may be a continuous oscillation about a small angle (e.g., 5 to 30 ). Oscillation or other pivoting can follow a programmed pattern, in order to spread out the melt stream on the wheels and equalise the build up of the wool layer on the collecting conveyor.

This will also increase the output from the spinning system, and will decrease the wear on the spinning wheels, compared to traditional spinners. Often the drive of each or some of the individual driven support also moves the rotor (and the entire rotor unit) axially within the duct.

Preferably each driven support is in the form of an arm assembly which is mounted at a point on the duct wall and which includes a suitable drive. This drive will allow for extension or the retraction of the arm lengthwise and for rotation of the arm about its mounting point, generally within a radial plane. Often it will also allow for movement of the arm about its mounting point along the axis of the duct. Often it will allow for twisting of the arm about the axis of the arm, thereby providing for angular movement of the axis of that rotor relative to the axis of the duct.

The drive for each driven support can be by a hydraulic cylinder or appropriate robotic control. The drive can be controlled manually or, more usually, wholly or partially automatically in response to, for instance, the quantity of melt, the quality of melt (eg its chemical type, its temperature and/or its viscosity) and/or the air flow through the duct and/or the nature of the MMVF product which is being made by the apparatus.

As a result of the ability to move independently at least two of the rotor units and usually all of the rotor units with any desired selection of two, three or four degrees of freedom it is possible to obtain very accurate response to melt and other conditions so as to optimise the production of fibres at any particular instance.

Additionally, the control for each unit will generally include means for adjusting the speed of rotation of the motor for that unit, thus giving further opportunity to provide additional automatic, semi-automatic or manual control of the process.

Preferably the support means include a releasable coupling which allows individual rotor units to be removed from the duct without interfering with the other rotor units.

A further advantage of the invention is that when break down on a single rotor occurs, it will be possible to adjust the rotor configuration, so that only the remaining rotors will be able to continue the spinning process during repair or substitution, with only a loss of perhaps 20% in spinning efficiency, instead of stopping the whole production line.

Each subsequent rotor, and usually also the first rotor, is usually provided with an air slot or other means for blasting primary air forwards across the surface of that rotor, for instance the air slot having an inner diameter substantially the same as the outer diameter of the rotor. Thus the air has a component of velocity in the substantially axial direction. The air may move wholly axially but often it also has a major tangential component, for instance as described in W092/06047 and PCT/EP96/02068.

There may be blades or other direction means in the air slot.

The individual rotor units are usually mounted wholly independent of each other, i.e. with no rigid connection between the rotor units. This can give the advantage of providing a larger space for air flow through the duct then when all the units are enclosed within a single housing.

There may be a space between the rotor units through which air can travel. However if desired the passage of air between the rotor units can be reduced or prevented by it providing appropriate shielding means. For instance a shield may be provided behind the set of rotor units so as to impede the axial flow of air between the rotor units and/or a shield may be located at a position between the rotors and the associated motors. If this shield is a collapsible plate or a plate having apertures significantly smaller than the diameter of the rotors but larger than the diameter of the axes of the rotors, a considerable independent movement of the rotor units can be conducted in accordance with the invention whilst maintaining an effective shield to prevent passage of air between the rotors.

The front end of the duct must be open in order to allow for the flow of transport air around the set of rotor units so as to carry the fibres forward from the front end of the duct. Often the rear end of the duct is also open so as to allow free flow of air through the duct.

Alternatively the rear end can be closed and forced air can be fed into the rear of the duct.

As a result of being able to vary performance by varying the position and speed of each rotor, it can be preferred for two or all the subsequent rotors to have the same diameter. The invention can result in better utilisation of binder and melt, and lower maintenance costs.

The apparatus will generally discharge towards a collecting chamber, which can be conventional.

Reference should be made to PCT/EP96/02068 and GB 9509782.0 for a full description of suitable constructions and use of the rotor units, the duct, and the collecting chamber. Preferred apparatus of the present invention is as claimed in PCT/EP96/02068 and as described in that but with the modification of the individual support means as described herein.

The present invention also includes making MMV fibres using the novel apparatus.

The invention is illustrated in the accompanying drawings in which Figure 1 is a longitudinal horizontal cross section of apparatus according to the invention (taken on the line I-I in Figure 2) Figure 2 is a longitudinal vertical cross section of the same apparatus (taken on the line II-II in Figure 1) Figure 3 is a transverse cross section taken on line III-III in apparatus similar to Figure 2 and shows the novel spinner in more detail.

Figure 4 is a longitudinal cross section of the spinner shown in Figure 3, taken on the line IV-IV (not to scale).

The apparatus comprises a cascade set 1 of rotor units located to discharge into a chamber 2 which comprises a collecting portion 3 which has a spinner end 4 adjacent to the cascade spinner 1, and a spinner portion 5. This spinner portion 5 has a rear end 6 which is open to the atmosphere and a front end 7 which opens into the spinner end of the collecting portion 3.

There is a substantially tubular duct 8 extending between the front end 7 and the rear end 6. The front end 7 of the duct 8 defines with the set of rotor units an open substantially annular collar 9. Air can be induced to flow through this collar from along a passage 10 extending back from the collar 9 towards the rear end 6.

In the apparatus which is shown, the collar 9 merges with and is coextensive with the passage 10, since the set of rotor units 1 and duct are both shown as being substantially parallel sided. However if the tubular duct 5 is, for instance, in the shape of a converging cone the annular passage 10 will have decreasing open area towards the front of the set 1, and the relevant open cross sectional area around the spinner for axial forward flow of induced air from the passage will then be the collar 9 between the set and the front end 7 of the spinner portion 5. The duct has an outward flange 63 at its rear end, but is open at its rear end.

The collecting portion 3 has side walls 12, end walls 13 merging with the spinner portion, a top wall 14 merging with the spinner portion and with the side walls, and a base comprising a pit section 15 and an inclined conveyor 16. Behind the collector 16 there is a suction chamber 18 from which air is drawn by a suction pump 19. The suction chamber 18 is coextensive with the collector 16 and thus sucks air from the collection portion over the entire area of the collector, although the greatest amount of suction will be applied where the web is thinnest.

The collector 16 is conveniently a slatted conveyor belt or other porous carrier that can run continuously around rollers 20, 21 and 22.

During operation of the apparatus, fibres collect on the collector 16 to form a thin web 23 which is carried upwardly by the collector and is taken off by the take-off apparatus 24. From that position it can be subjected to conventional treatments such as cross lapping and consolidation. Rollers 25 act as seals to prevent significant ingress of air around the conveyor.

The pit zone 15 includes a trough 26 set in the base of the pit area and having a closed end and a sluice or rotary valve at the opposite end (not shown). A screw conveyor 27 rotates within the trough 26 to carry shot which collects in the trough out through the sluice or valve. This openable end may be permanently open, provided that it is designed such that only a limited amount of air can enter through it, or it may be opened from time to time to allow the discharge of shot by the conveyor from the trough.

There are air guide baffles 32 in each side of the collecting chamber extending from the wall 12 to an open edge 33. These air guide baffles 32 diverge outwardly substantially conically from the edge 33 which is adjacent to the open end 7 of the spinner portion. The top wall 14 also extends substantially conically upwards. Preferably the angle that the top wall and each of the air guide baffles makes to the axial direction is not more than about 450, preferably about 15 to 300.

There is a shot collecting zone 35 around the open end 7 of the spinner portion. One side of the collecting zone is defined by the chamber end wall 13 and the other is defined by the edge 33 and the baffle 32. Shot thrown radially outwards from the spinner is thrown through the gap between edge 33 and wall 13 into the zone 35. The side wall 12 merges inwardly near its base with the baffle 32 so as to cause shot that slides down the collecting zone 35 to fall into the trough 26.

The set of rotors 1 which constitutes the spinner is shown more clearly in Figure 3. Although in Figures 1 and 2 the set is centred above the centre of the duct, in the embodiment shown in Figure 3 it is centred on the centre of the duct or slightly below.

The set consists of a first rotor 43, and subsequent rotors 44, 45 and 46, constituting the second, third and fourth rotors of the set respectively.

Each rotor is mounted on an individual driven support arm 47 which is mounted on the duct 8 at its respective mounting point 48. A robot control, hydraulic cylinder or other suitable drive 49 for each is provided for giving suitable independent drive capacity to each support arm 47.

Only one set of parts 47, 48 and 49 is shown in Figures 1 and 2. As is shown in connection with the support arm 47 for the rotor 44, the drive provides several different degrees of freedom and movement of the end of the arm on which the rotor unit is mounted, and thus several different degrees of movement of the rotor unit itself.

As shown by arrow 50, one degree of movement is extension and retraction of the arm. Another, as shown by arrow 51, is radial movement about the mounting point 48.

This radial movement can be wholly within the radial plane that passes through the mounting point 48 or the radial movement can be both in this plane and transverse to this plane (thus giving axial movement). Thus, while holding rotors 43, 45 and 46 in unchanged positions it is possible to move rotor 44 from the position shown in the drawing to one which is vertically downwards, horizontally sideways, rearwards or forwards or any combination thereof.

If the mounting point allows for swivelling about the axis of the arm, as shown by arrow 52, then it is additionally possible to alter the angle of the axis of the rotor 44 relative to the axis of the duct.

Each of the second, third and fourth rotors is provided with an annular slot 53 through which air can be forced as a wall jet over the surface of the rotors 44, 45 and 46. Blades are positioned in the slot set at appropriate angles so as to impart a derived tangential component to the air at different positions around each slot.

As shown in Figure 4, the rotor unit 54 which includes rotor 44 includes an outer cylindrical casing 55 in which the motor 56 for the rotor is mounted and which encloses an axial drive 57 interconnecting the motor 56 and the rotor 44. The annular air slot 53 is positioned between the outer housing 55 and the outer surface of the rotor 44 and is supplied by air forced through the housing 55 by a blower (not shown). The support arm 47 is suspended at point 48 from the venturi wall 8 by a hinged joint 57.

Conventionally the support arm 47 includes a coupling 58 allowing for easy mounting and dismounting of the rotor unit. The arm may be hollow and preferably carries the primary air supply to the air slot 53, cables 59 and other supply means for binder, cooling water and power.

Each of the other rotor units may be of similar construction.

Claims (9)

1. Apparatus for forming MMV fibres comprising a duct defined by a substantially tubular wall (8) and which is open at its front end (7), a set (1) of rotor units (54) mounted within the duct each comprising of a rotor (43, 44, 45, 46) mounted for rotation about a substantially horizontal axis substantially in the front end (7) of the duct and a substantially coaxial drive motor (56) behind the rotor, wherein the set of rotor units consists of a first rotor unit and at least one subsequent rotor unit whereby melt poured onto the first rotor (43) is thrown onto the or each subsequent rotor (44, 45, 46) in sequence and is thrown off the or each subsequent rotor and optionally off the first rotor as fibres, and support means (47, 48, 49) for supporting the set (1) of rotor units from the duct wall (8), characterised in that the support means comprise individual driven supports (47) for at least two of the rotor units wherein each individual support extends between the duct wall (8) and the rotor which is supported by that support, and a drive (49) for moving that rotor independent of the other rotors with a movement which has independently selected vertical and horizontal components and/or which has independently selected pivoting about a substantially vertical axis.

2. Apparatus according to claim 1 in which the drive in the said individual driven supports is also for angular movement of the axis of that rotor relative to the axis of the duct.

3. Apparatus according to claim 1 or claim 2 in which the drive in the said individual driven supports is also for movement of that rotor axially within the duct.

4. Apparatus according to any preceding claim in which each driven support is in the form of an arm assembly which is mounted at a point on the duct wall and which includes a drive for extending or retracting the arm lengthwise and for rotating the arm within a radial plane.

5. Apparatus according to claim 4 in which the drive is also for moving the rotor unit along the axis of the duct.

6. Apparatus according to claim 4 or claim 5 in which the drive is also for twisting the arm about its axis.

7. Apparatus according to any preceding claim including means for blasting primary air forwards across the surface of the or each subsequent rotor.

8. Apparatus according to any preceding claim including means for adjusting individually the speed of rotation for each of the rotors separately from each of the other rotors.

9. A process for making MMV fibres using apparatus according to any preceding calim in which at least one of the support means is activated during the process to move its rotor unit in response to other changes in the process conditions or in the derived product.