This invention addresses technical problem monitoring characteristics of a melt cascade (for purposes of this invention this term describing melt in either droplets, or streams, or rivulets, or other type of flow cascading from furnace or like through melt vessel, and onto rotating wheel or plurality thereof, and between said rotating wheels) which is formed in production of mineral fiber (so, called mineral wool as known in state of the art being stone wool slag wool or other type of mineral wool). This production comprises mainly of pouring of melt, preferably in form of a jet or a stream, said melt comprising material to be solidified into fiber, onto said rotating wheels(in state of the art also known as rotors) comprising of a first rotating wheel where melt is to be solidified (at least in part) in form of fibers which are blown off said rotating wheel, remainder to be passed to the second rotating wheel and thrown back onto the first rotating wheel and to third rotating wheel and so forth (of course assuming that there are more than one rotating wheel). In addition to monitoring, technical problem is also to ascertain where the production is performed with at least waste as possible.

State of the Art

A typical fiberizing apparatus in state of the art is described in EP 1409423. Typical spinning machine consists of 3 to 4 fiberizing rotating wheels, also known as the spinning wheels, or rotating wheels (term used in this patent application), or rotors.

The mineral melt discharged from the melting furnace or similar device for heating up and melting raw materials used in mineral wool formation forms a nearly vertical melt stream as it is poured onto the spinning machine. The melt stream is directed towards the mantle surface of the first wheel where it partly adheres to the surface, is drawn in motion and forms a melt film. A part of the melt forms, with the aid of the centrifugal force, liquid ligaments that solidify to the mineral wool fibers while the remaining quantity of the melt is thrown out as a cascade of drops against the mantle surface of the adjacent second wheel in the series. Again, a part of the melt adheres to the second wheel surface sufficiently to be formed into fibers and the remainder is thrown onto the mantle surface of the third wheel of the spinner machine and so forth, until the last wheel where the remaining mass flow of the melt is assumed to be low enough to fiberize completely.

Binder may be applied on the formed mineral fibers, either during fiber formation or afterwards, in form of a droplet spray. The mineral fibers formed on the wheels of the spinning machine are transported away from the point of origin on the melt film, initially in the radial direction due to the centrifugal force. As the fibers enter the zone of the coaxial air flow generated by the spinning machine fan, i.e. the blow-in flow, they are drawn in predominantly axial motion and transported to the collecting chamber where the primary layer of the mineral wool is formed.

None of patents searched showed any monitoring method or means.

Fiber formation is achieved through competing centrifugal force and air entrainment force by virtue of air blowing onto the rotating wheel on one side, and viscous and surface tension forces keeping melt film to the rotating wheel on another side. When former exceed latter the melt is lifted from the rotating wheel, the droplets are elongated until they stretch and solidify in form of a fiber. The process may vary from this description, however, this does not alter the essence of this invention as described below.

For purposes of this application progression of melt from one rotating wheel to another is called melt cascading.

Description of new invention

Method, and an apparatus for monitoring melt stream within fiberizing apparatus solves above referenced technical problem by steps of determining (a) trajectory of movement of melt stream, (b) melt concentration relative to surrounding air between the first and the second rotating wheels, and (c) movement vector. This method provides for contact- less evaluation of movement of melt stream, and the result could be used for regulation of impingement point between melt stream and the first rotating wheel which in turn enables operation within optimum regime according to this invention.

Optimum regime in accordance with this invention is governed by compromise between minimum fraction of solidified shots, i.e. parts of the melt which are not transformed into fiber, and freeze during this process and production yield on other hand. This regime can be observed in Figure 6, and is signified by an arrow - of course, in real life application, and also claimed by this patent application is area to the left and to the right to the arrow's point. Optimum regime (31 in Fig. 6) is approximately bound by (34) as minimum angle of impingement point between melt stream and the first rotating wheel (7), and (35) as maximum angle of impingement point between melt stream and the first rotating wheel (7).

Apparatus according to this invention comprises monitoring means, and evaluation of melt cascade features means. Monitoring means are comprised at least of a camera operating within visual part of a light spectrum, and data acquisition means known in state of the art recognizing intensity of light (intensity of luminance) is emitted from melt cascading.

Steps comprised in the method according to this invention may also be direction, position, and velocity of movement of melt cascade, said melt predominantly in form of droplets, and further, information on position of melt film on rotating wheel or plurality thereof.

Regulation as a result of this invention therefore depends on trajectory of movement of melt cascade, concentration of melt between the first and the second rotating wheel, and movement vector (i.e. velocity) of said melt cascade.

For purposes of this application "spinning rotating wheel" is also referred to simply as "rotating wheel". For purposes of this application, and unless explicitly noted otherwise, words left, right, up, down, vertical, horizontal, forward, backward do not mean strict expressions but rather they should be understood as essentially, or approximately left, right, up, down, horizontal, vertical, forward, and backward and they should be interpreted as these expressions would be understood by one skilled in the art.

The foregoing aspects and many additional advantages of this invention will become more readily appreciated by reference to the following detailed description, below, when taken in conjunction with the accompanying drawings, all forming part of this patent application, wherein

Figure 1 shows the first rotating wheel (1), the second rotating wheel (2), the third rotating wheel (3), the fourth rotating wheel (4), melt container (5), melt stream onto the first rotating wheel (6), impingement point between melt stream and the first rotating wheel (7), melt stream from the first rotating wheel onto the second rotating wheel (8), melt stream deflecting from the second rotating wheel onto the first rotating wheel (9), melt stream from the second rotating wheel toward space in-between the third and the fourth rotating wheels (10), film on the first rotating wheel (11), film on the second rotating wheel (12) , film on the third rotating wheel (13) , film on the fourth rotating wheel (14), direction of blowing air (15).

Figure 2 shows an edge of the first rotating wheel (16), an edge of the second rotating wheel (17), geometric center between the first and the second rotating wheel (18), distance between a center of a melt trajectory to the edge of the first rotating wheel (19), distance between the center of the melt trajectory to the edge of the second rotating wheel (20), the melt trajectory (21), an area for luminance detection for the first rotating wheel component (22), an area for luminance detection for the second rotating wheel component (23).

Figure 3 shows the first rotating wheel (1), the second rotating wheel (2), the melt stream from the first rotating wheel onto the second rotating wheel (8), impingement point between melt stream and the second rotating wheel (24), melt stream from the second rotating wheel into area between the wheels above axis connecting the center points of the first and the second rotating wheels (25), melt stream from the second rotating wheel into area between the wheels below axis connecting the center points of the first and the second rotating wheels (26), vector of melt movements below connecting the centers of the first and the second rotating wheels (27), axis connecting the centers of the first and the second rotating wheels (28).

Figure 4 shows vertical reference (29), horizontal reference (30), area of melt stream inflow (31), the far right position of melt stream inflow related to geometric center between the first and the second rotating wheel (32), the far left position of melt stream inflow related to geometric center between the first and the second rotating wheel (33), the far right position of melt stream inflow regarding an angle with respect to vertical axis of the first rotating wheel (34), the far left position of melt stream inflow regarding an angle with respect to vertical axis of the first rotating wheel (35).

Figure 5 shows collecting chamber (36), camera (37), direction of melt container positioning left/right (38), direction of melt container positioning forward/backward (39).

Figure 6 shows the area of melt stream inflow (31), portion of melt flowing between the first and the second rotating wheel with respect to melt stream inflow position (40), portion of formation of non-fiberized material with respect to melt stream inflow position (41).

Figure 7 is presented for better understanding of the reader, and is photograph from actual experiment which has been for purposes of this application redrawn in figure 2.

Figure 8 is presented for better understanding of the reader, and is photograph from actual experiment which has been for purposes of this application redrawn in figure 3.

Figure 9 is presented for better understanding of the reader, and is photograph from actual experiment which has been for purposes of this application redrawn in figure 4. It should be immediately presented that scope of this invention is not limited by number of rotating wheels. For purposes of this invention it is sufficient if fiberizing apparatus has at least one rotating wheel, preferably two rotating wheels. Four rotating wheels are presented as such apparata are known in the art, and as the principles can be explained better with four rotating wheels. It should further be noted that it is also possible for this invention to function to have only three wheels thus rendering the fourth rotating wheel unnecessary for purposes of this application. Further, more than four rotating wheels can be used. However, most common setup seems to be that of four wheels therefore the invention is described with this setup but this should not be seen as a limiting factor as two, three, four, five or more rotating wheels fiberizing apparatus (also known as "spinning machine") are both possible, and viable, depending on other factors comprising one or more characteristics such as (for informative purposes only) viscosity, density, mineralogical setup or other characteristics of melt, and/or minimum distance, rotational speed, material of rotating wheels or other characteristics of a device.

In present embodiment the melt coming into contact with the first rotating wheel (1) is partially comprising a film (11) primarily as a result of viscous forces and surface tension. The remainder of the melt is transported onto the second rotating wheel (2) preferably in form of melt stream (8). Part of this melt again forms a melt film (12) on the second rotating wheel (2), another part forms a melt stream (10) flowing between the first (1) and the second (2) rotating wheel, and the remainder (9) is thrown back into the first rotating wheel (1).

Space between both rotating wheels (3) and (4) is filled with part of the melt from rotating wheel (2), part of the melt from rotating wheel (1) and part of the melt which has passed in between both rotating wheels (1) and (2). It should be noted that rotating wheels (3) and (4) are not necessary for carrying out this invention, and that melt cascade with only rotating wheels (1) and (2) is possible (so called two wheel fiberizing apparata as known in state of the art). Further, part of film (11) from perimeter of rotating wheel (1) and part of film (12) from perimeter of rotating wheel (2) is transported to rotating wheels (3) and (4) as a consequence of centrifugal force acting on films (11), and (12), respectively.

In the axial direction (meaning the direction essentially normal to plane in which the first rotating wheel essentially rotates, or direction essentially co-linear to axis of the first rotating wheel), velocity of blowing air (15) is acting on the film. It should be immediately mentioned that this direction is not limiting for this invention, and that the air (which represents blowing or blow-off means) may blow in any desired direction, including essentially within the plane in which the first rotating wheel essentially rotates). This air is aiming to entrain the melt (usually in form of droplets) and blow it off the rotating wheel. When total force of air flow and centrifugal component acting on the film overcomes viscous and surface tension components as well as possible forces keeping film on said rotating wheels, the film is gradually deformed, and a droplet formed. This droplet is entrained by air flow, and elongated in direction of air flow force and centrifugal force resultant. The droplet is therefore transformed into a fiber which is even more elongated until it solidifies and falls in the collecting chamber or other device for collecting this fiber or plurality thereof.

The quality of fiber formation is dependent on distribution of melt concentration on different wheels, and this concentration, in turn, depends on cascade movement of melt mass (8), (9), and (10). This, in turn, depends on melt stream (6) contact characteristics with the first rotating wheel (1), especially the impingement point (7).

In order to proof this, several tests were performed, images of which are also presented in Figures 7 through 9 in this patent application.

Impingement point for purposes of this application means approximate center of the melt stream inflow impact position. Such a center cannot be determined with large degree of accuracy, so it should be interpreted having in mind one skilled in the art. Hence, any reference to impingement point should be interpreted likewise, i.e. approximate reference to approximate center of the melt stream inflow impact position. The results of tests are presented in form of a graph in Figure 6.

The abscissa in Fig. 6 shows the position of impingement point between melt stream and the first rotating wheel, expressed in degrees. 0° means that the impingement point is approximately in top dead center of the first rotating wheel. 90° means that approximate center of the melt stream inflow misses the first rotating wheel and falls in space between the first and the second rotating wheel. Both curves present quality (in terms of shot content), and quantity (in terms of fibers) depending angle between top dead center of the first rotating wheel and impingement point (7). Curve (40) in Fig. 6 presents quantity of melt in % which passes between the first and the second rotating wheels, and the difference to 100 % is percentage of melt which is in contact with both the first and the second rotating wheels. Curve (41) in Fig. 6 presents ratio between actual shot content and maximum shot content at impingement point 0° [%]. These shots are also considered waste for purposes of this patent application, hence, minimization of shots is one of goals of this application. The other goal is also to minimize amount of non-transformed melt material, and in order to be able to do this, novel monitoring and/or regulation method and apparatus are proposed herein.

The ordinate in Fig. 6 on the left shows portion of melt flowing between the first and the second rotating wheel with respect to melt stream inflow position (40), the ordinate in Fig. 6 on the right shows portion of formation of non-transformed melt (non- fiberized) material with respect to melt stream inflow position (41). From this graph it is evident that the optimum operating point (to address one of technical problems of this invention) is where both curves (40) and (41) intersect.

The subject of this invention is therefore a method by which determination of impingement point between melt stream and the first rotating wheel (7) is performed in such a way that three key parameters are determined: (a) trajectory of movement of melt stream, (b) melt concentration relative to surrounding air between the first and the second rotating wheels, and (c) movement vector. The apparatus should therefore possess the means for (a) determining the impingement point between melt stream and the first rotating wheel (7) based on solidified percentage of shots and production yield, and (b) comparing said impingement point between melt stream and the first rotating wheel (7) with optimum operating range, and further this apparatus should posses regulation system connected to said apparatus for ensuring that said impingement point between melt stream and the first rotating wheel (7) is within optimum operating range.

The apparatus should therefore further possess the means for determining (a) trajectory of movement of melt stream, (b) melt concentration relative to surrounding air between the first and the second rotating wheels, and (c) movement vector and analytical system connected thereto. ^{■ ·}

In embodiment of this invention these objectives are met by apparatus of monitoring and regulation of melt stream (which can be even in predominant form of droplets) movement. Apparatus is comprised of two parts: part for monitoring (optionally comprising evaluation of process), and part for regulation which is carried out by regulation of the impingement point between melt stream and the first rotating wheel (7).

Apparatus for monitoring comprises a camera (37) which can be any type of digital camera, preferably (due to price) operating within visual spectrum, however, any spectrum (including IR, for different reasons) is possible. Said camera (37) is set up in general axial position relative to the rotating wheels on the upper part of collecting chamber (36). This position enables camera to capture image or plurality thereof of melt stream movement and in-depth information on film position on relevant rotating wheels as well as the impingement point between melt stream and the first rotating wheel (7). Preferred position of camera is 25° to 50° relative to the first rotating wheel axis which permits capturing in-depth information on (29)

Captured image or plurality thereof is analyzed by means of image processing on a computerized system in real time taking advantage of three key parameters measured by proposed apparatus, and method: (a) trajectory of movement of melt stream, (b) melt concentration relative to surrounding air between the first and the second rotating wheels, and (c) movement vector.

Trajectory of movement of melt stream is according to this invention connected to intensity of luminance of said melt. Higher the intensity, larger the concentration. Following the highest points of intensity (luminance) within same monitoring window (region of interest), and connecting said highest points results in the melt trajectory (21).

Parameter of a horizontal trajectory point is determined as a difference between detected melt trajectory (21), and geometric center between the first and the second rotating wheels (18) which is determined relative to an edge of the first rotating wheel (16), and an edge of the second rotating wheel (17). Deviation of said trajectory (21) from the edge of the first rotating wheel (16) is given by a distance between a center of a melt trajectory to the edge of the first rotating wheel (19), and the deviation of said trajectory (21) from the edge of the second rotating wheel (17) is given by a distance between the center of the melt trajectory to the edge of the second rotating wheel (20).

Integral parameter of trajectory (21) is in this invention defined as average value of set of vertical points between said trajectory (21) and geometric center between the first and the second rotating wheels (18), vertical from a impingement point between melt stream and the second rotating wheel (24) to upper level of the third rotating wheel (in case of fiberizing apparatus with three rotating wheels), or the third and the fourth rotating wheels (in case of fiberizing apparatus with four or more rotating wheels), or to some predetermined position (in case of fiberizing apparatus with two rotating wheels).

Further parameter which needs to be determined is distribution of concentration. This distribution is determined by calculation of integral value of luminance in the area for luminance detection for the first rotating wheel component (22) and in the area for luminance detection for the second rotating wheel component (23), both in space between the rotating wheels, and normalized to a reference value presented by area of the first rotating wheel (1) for the first rotating wheel (1), and the area of the second rotating wheel (2) for the second rotating wheel (2). The border between the first (1), and the second (2) rotating wheels is determined as geometric center between the first and the second rotating wheel (18).

Further parameter to be determined is movement vector. This vector describes movement of plurality of melt, and can therefore be regarded as analogous to lumped parameter modeling analysis. There are two vectors given: the first for the upper part, and the lower part. The former is the vector for melt stream from the second rotating wheel into area between the wheels above axis connecting the center points of the first and the second rotating wheels (25) while the latter is the vector for melt stream from the second rotating wheel into area between the wheels below axis connecting the center points of the first and the second rotating wheels (26).

The first vector is defined as detected value in the direction of tangential component of the melt stream from the first rotating wheel onto the second rotating wheel (8) in the impingement point between melt stream and the second rotating wheel (24) to the axis connecting the centers of the first and the second rotating wheels (28). The second vector is defined below the axis connecting the centers of the first and the second rotating wheels (28), and its direction is defined by the vector of melt movements below axis connecting the centers of the first and the second rotating wheels (27).

Further parameters to be taken into consideration are reference values. The camera (37) is capturing the image which is projection of 3D onto 2D. The position of melt stream therefore varies due to freezing of melt, changing thermodynamic properties, and camera vibrations (as observed consequence of collection chamber vibrations). This is a problem which is addressed by setting up the reference areas to which other spatial and luminance analyses are referenced to.

The vertical reference (29) is detected as film position on the first rotating wheel. Due to angular position of camera (37) triangulation is used to calculate in-depth position of the stream. The horizontal reference (30) is position between the first rotating wheel and the second rotating wheel where the distance between the first rotating wheel and the second rotating wheel is the minimum.

Further step to be determined is an elimination of noise (interfering values). Lumps of non-fiberized material (non-transformed melt) are interfering with data acquisition. To eliminate their influence the program performs dynamic analysis in short time intervals. Elimination of interference is achieved by attributes of non-validity of detection in areas of luminance with high frequency.

Having determined all steps necessary for carrying out this invention so far, the following technological parameters of operation were identified:

(a) the average relative trajectory (21) position is less thaa 40% the minimum distance in vertical direction varying from the impingement point between melt stream and the second rotating wheel (24) to the axis of of the first and the second rotating wheels (28);

(b) the luminance intensity in the area for luminance detection for the second rotating wheel component (23) is at least 45% of luminance sum in the area (23) and (22), where (22) is the area for luminance detection for the first rotating wheel component in lower space between the rotating wheels, i.e. from the axis of of the first and the second rotating wheels (28) generally in downward direction to lower edge of the first or the second rotating wheels, respectively, i.e. from the axis of the first and the second rotating wheels (28) generally in downward direction to lower edge of the first and the second rotating wheels.

(c) the direction of the vector of melt movements below axis of the first and the second rotating wheels (27) of the melt stream from the second rotating wheel into area between the wheels below axis of the first and the second rotating wheels (26) in the lower space between the rotating wheels is less than +15°, where 0° stands for vertical direction downward, and positive direction is counterclockwise direction.