EP0329686B1

EP0329686B1 - A process and device for feeding a thin binder impregnated uncured primary web of mineral wool onto a receiving conveyor

Info

Publication number: EP0329686B1
Application number: EP87907241A
Authority: EP
Inventors: Henning John Emil Lauren
Original assignee: Partek Oy AB
Current assignee: Partek Oy AB
Priority date: 1986-10-31
Filing date: 1987-10-29
Publication date: 1992-05-13
Anticipated expiration: 2007-10-29
Also published as: CN87107553A; RO104627B1; FI83674B; FI864452A0; PL158611B1; PL268494A1; FI83674C; CN1009911B; FI864452A; RU1831533C; EP0329686A1; BG50603A3; KR890700106A; WO1988003121A1; AU607169B2; AU8174587A; JPH02500737A; HUT49826A; CA1289981C

Abstract

A process for feeding out a primary web of mineral wool onto a receiving conveyor. For this purpose, a pendulum conveyor has been used. In order to achieve good quality and the desired capacity the primary web must be thin and output rate high, which causes problems in fixing the primary web into the already fed out web and in looping the edges of the fed out web. According to the invention, these problems have been solved by making the trajectory and rate of motion of the output end (10) of the receiving conveyor (2) to comprise a central portion (B1) with a constant speed, which equals or is close to the output rate of the primary web, and an outmost portion (B2) having a retarding or accelerating speed, respectively. By this means the output end may move close to the receiving conveyor and be rapidly fixed into the bed while the pendulum allows appropriate space in the extreme positions for the edge loop, which also is rapidly fixed into the bed and forms an even edge. The invention relates also to a device for carrying out the process.

Description

The present invention relates to a process for feeding a thin binder impregnated uncured mineral wool web on a receiving conveyor and to a device for carrying out the process according to the preamble of claims 1 and 9.
When manufacturing mineral wool sheets, it is crucial to achieve a product that is as uniform and homogeneous as possible, yielding a higher insulation capacity. Moreover, it should be as elastic as possible at a low density, requiring the fibres to extend mainly in the sheet plane. Due to the elasticity, the sheet may be compressed for packing and transport purposes.
In achieving this a thin primary web with a mean weight in the range of 110 to 450 g/m², preferably 100 to 200 g/m², is collected on a collecting conveyor immediately after the fiberization. The thinner the primary web, the better the quality of the finished product. To keep the capacity at the desired level while producing a thin primary web, the speed of the primary web as well as that of its conveying devices has to be high. Normally, the speed of the primary web is over 100 m/min, however, the mean weight of the primary web being as low as 100 to 200 g/m², an even higher speed is required to keep the capacity at the desired level. This primary web is then folded to a final, so-called secondary web of desired width and thickness.
Various methods for folding mineral wool webs are described i.e. in the US Patent Specification 2450916 and in the somewhat later GB Patent Specification 772628. These have subsequently been completed with methods for folding the primary web by means of pendulum conveyors.
When pendulum conveyors are used for feeding out a primary web, it is critical that the speed of the output end is about the same as that of the primary web, to avoid folding or stretching of the web at the output moment.
In the regular pendulum operation, the turning points are highest above the receiving conveyor, and the lower dead point of the pendulum is closest to the receiving conveyor. To achieve the desired capacity with thin primary webs, the output rate of the pendulum conveyors should increase, but this is not feasible with known devices. In fact, a high speed pendulum conveyor that feeds out a light web and has a high pendulum frequency, yields an inexact laying of the primary web. A pendulum conveyor driven in a known manner be a connecting rod, and oscillating along a circular arc, imparts a speed to the output end of the conveyor that is maximal when the pendulum is in the middle position and decreases sinusoidally to zero at the turning point, from where a sinusoidal acceleration recurs. That output end of such a pendulum conveyor must, in its lowest position, by ca 0.2 times the output width, (normally 2 m) above the out-fed mineral wool web, to allow the primary web to be deposited in a uniform layer on the receiving conveyor without being stretched. The distance between the pendulum and the receiving conveyor being that long (up to 40 cm and more), the web fed out will get uneven edges. The output rate being c. 130 m/min, the irregularities of the secondary web formed will be ca +/- 5% of the output width. This signifies that the secondary web must be made correspondingly larger to achieve a faultless web of the desired width, since the undesired material has to be cut off. This means a great loss of material.
Pendulum output mechanisms, in which the folding process is carried out by continuously feeding out the primary web at a constant height above the support, are also known e.g. from US-A-3222730. An articulation system is provided for maintaining the output end of the pendulum mechanism at a constant height above the receiving conveyor, and the to and fro motion is obtained by a chain/connecting rod-mechanism. The speed profile of the oscillating motion has a constant speed period in the middle and a sinoidal retardation and acceleration phase in each end position. The pendulum must be rapidly retarded and accelerated in the end positions for the pendulum motion to correspond to the output amount of the primary web per unit of time, causing great strains in the mechanical constructions. Consequently, the mechanism can be used only at output rates below ca 100 m/min.
Another drawback with pendulum mechanisms having a high pendulum frequency is the strong air turbulence generated by the rapid to and fro motion of a pendulum mechanism having a large surface. The air flows disturb the depositing of the thin primary web on to the bed.
Pendulum mechanisms for feeding thin primary webs in overlapping layers on a receiving conveyor are thus previously known. However, they all present considerable drawbacks; the edges of the final web are uneven causing great loss of material, the speeds are too low to fulfil the capacity requirement, the retardation and acceleration forces are great, causing great mechanical stress in the constructions; the problem of air flows jeopardizes the deposition of the primary web.
From US-A-3222730 are known a method and a device for folding according to the preamble of claims 1 and 6.
The purpose of the present invention is to reduce or totally eliminate these drawbacks, and especially to obtain an exact laying-out with even edges and a web with high homogeneity, and this has been achieved by providing a method and a device, of which the main characteristics are presented in claims 1 and 6. In a preferred embodiment of the invention a prior known drive system is used, imparting to the oscillating pendulum conveyor, called pendulum from now on, a constant rate of motion in the middle of the pendulum motion and a sinusoidally decreasing or increasing speed in the end parts of the pendulum motion. The period of constant speed may extend over 30 to 60%, preferably 50% of the entire pendulum swing. The constant speed of the pendulum in the middle part of the stroke equals totally or nearly totally the output rate of the primary web. This enables the pendulum to be disposed closer to the receiving surface, at about half the distance allowed by conventional crank drive, thus ensuring considerably better deposit and fixation of the primary web on the receiving conveyor.
Outside the constant speed area, the pendulum is driven at a sinusoidally decreasing or increasing rate, while the pendulum continues its pendulum motion. At least during part of the motion at a decreasing or increasing rate in the extreme positions of the pendulum swing, the output end of the pendulum is arranged to rise in the final phase of the pendulum motion and to sink in the initial phase. Due to the changing of the height of the pendulum in the retardation or the acceleration phase, potential energy is stored and discharged respectively. This results in less stress forces on the mechanism than those generated when the output end of the pendulum describes a horizontal path over the entire pendulum swing.
The pendulum motion, consisting of a middle part with a constant speed and two outer parts with retarding and accelerating speeds, respectively, is appropriately produced by means of an endless drive chain running over two coplanar interspaced chain wheels, whereby a connecting rod connects the pendulum with a carrier on the drive chain. The centre distance of the chain wheels corresponds to the portion of the pendulum motion having a constant speed and half the circumference of each wheel corresponds to the pendulum motion having decreasing and increasing speed. Explained in more detail, the pendulum motion speed is decreasing when the carrier moves over the first quarter of the circumference, then increasing when moving over the following quarter of the circumference, then moving with constant speed over the distance between the midpoints of the chain wheels, and again with decreasing speed and after that with increasing speed over the two quarters of the circumference of the second chain wheel.
The pendulum motion consisting of a central portion having constant speed and two extreme portions having decreasing and increasing speed may also be produced by means of a so-called Ferguson gear, in which the rotary motion is transmitted by elliptical gear wheels.
The output end of the pendulum may be guided to move along differently shaped paths during the pendulum motion. The most simple embodiment is an arched trajectory, whereby the pendulum swings around a stationary bearing point. In such an embodiment, the pendulum operates with great accuracy at output rates of ca 200 m/min. This is enabled due to the fact that the output end of the pendulum may strike very close to the receiving conveyor, and closest thereto at the midpoint of the swing. The fed out primary web can then be immediately fixed into the underlying folded wool web and thus remains undisturbed by the air flows caused by the pendulum motion. In the extreme positions of the pendulum motion the lower end of the pendulum rises ca 0.1 times the output width, i.e. appr. 20 cm with an output width of 200 cm. This results in a more exact position of the edge folding, due to the smaller folding loop of the wool web. Another advantage of this embodiment is that the pendulum may be relatively short, ca, 0.7 to 1.0 times the output width, i.e. ca 140 to 200 cm, which results in lower moments of inertia and smaller stresses in the driving device. The air flow disturbances are also reduced by a shorter pendulum.
In this embodiment, the pendulum may be adjusted to stroke at its closest point only 5 to 10 cm above the receiving conveyor and thus to fix almost immediately the fed out web into the central area of the trajectory. This results in a wool web having very even edges. At a constant speed over ca 50% of the output width, which is 200 cm, and a maximum pendulum swing of 80% and a pendulum length of ca 75% of the output width, i.e. 150 cm, the pendulum rises c. 12%, i.e. 24 cm, in the extreme positions.
In another preferred embodiment of the invention the pendulum and its output end are made to move horizontally at a constant height above the receiving conveyor in the central zone of the pendulum swing and to rise above this in the outmost positions.
The rising motion may be started at any point after the mid-point of the pendulum motion, but at the latest during the retardation phase of the pendulum motion. The primary web, which is fed out from the output end of the pendulum at a constant rate, thus gets enough space under the raising output end which at the same time moves at a lower rate in relation to the receiving conveyor than the primary web. The rising motion thus starts, at the earliest, immediately after the mid-point of the pendulum motion, the pendulum and its output end then describing a continuous arched line. At the latest, it starts at such a point before the extreme position of the pendulum swing that enough space is formed under the rising pendulum for the accumulating loop to settle under control and to form an even edge during the reverse motion.
The locus of movement of th output end may be linearly rising, an arc of a circle or progressively arched or some of various combinations of these.
By means of various guide devices the pendulum, especially its output end, is forced to deviate from the natural pendulum motion having a circular output path. At the moment a deviation from the natural pendulum motion occurs, the oscillating point of the pendulum must be vertically moved or the swinging radius of the output end changed.
When an output feeding path consisting of a substantially horizontal central portion and arched end portions is desired, an arm is mounted pivotally in the pendulum from its one end and outside the pendulum from its other end, thus forcing the pendulum to describe an essentially horizontal path. During this part of the motion the oscillating point of the pendulum sinks/rises. The oscillating point is arranged to reach a stop or else to stop in the position where the pendulum is to go over to a rising motion. The pivotal mounting of the arm in the pendulum is arranged to enable the pendulum to oscillate with regard to the arm at the rising/sinking stage, e.g. by means of fork bearings. A spring may appropriately be disposed between the connecting rod top of the pendulum and the arm guiding the height position of the pendulum, whereby the acceleration and retardation forces are partly equilibrated in the extreme positions of the pendulum.
The motion of the pendulum may also be guided by e.g. a fixed guide disposed symmetrically with regard to the central axis along which a wheel mounted in the pendulum or a sliding body is arranged to move. The output feeding path of the output end will then correspond to the shape of the guide. The height of the guide above the output end is determined by the optimization of geometry and mass forces.
The oscillating point of the pendulum may alternatively be stationary while the output end is radially movable in relation to the oscillating point.
The invention will be described more in detail below as a number of preferred embodiments of the invention and referring to the enclosed Figures, in which:

FIGURE 1 is a schematic presentation of the pendulum motion in two preferred embodiments; the motion of the pendulum at a constant speed and subsequently at a retarded and an accelerated speed, while the output end of the pendulum describes a circular path (case A) and while the output end during the constant speed phase moves at a constant height above the receiving conveyor and during the retardation or acceleration phase moves along an arched path (case B);
FIGURE 2 shows a preferred embodiment of the pendulum including the associated driving device, the pendulum being shown in three different positions; and
FIGURE 3 shows another preferred embodiment of the pendulum including the associated driving device, showing the pendulum in three different positions.

In Figure 1, the right side of the Figure shows the case (A), in which the pendulum both during the period at a constant speed and the period at a retarded and an accelerated speed oscillates around the point P, which is stationary, the output end thus describing a circular arc. The pendulum is driven by the device D by means of a chain having a constant speed. A connecting rod V is mounted on bearings on a carrier to the drive chain at the point T and to the pendulum mechanism at the point K_A. In the driving chain the points I to XII have been marked, whereby the points I and VII indicate the mid position of the pendulum, the points IV and X the extreme positions of the pendulum and the points XII and II or VI and VIII the limits of the area having a constant speed. When the end T of the connecting rod is in the position I, the pendulum is suspended from the oscillating axis P and the position of the output end is indicated by the number I (a). From I to II the connecting rod moves at a constant speed and the output end describes a circular arc, since the oscillating axis P is stationary. From II to IV the pendulum moves with decreasing speed, changes the direction of motion at the point 4, moves from IV to VI with increasing speed and from VI to VII at a constant speed, while the output end describes a rising or a sinking circular arc. Depending on the position of the fastening point K_A on the pendulum with regard to the drive device D, more or less geometrical asymmetry is achieved, i.e. the points III and V or II and VI deviate somewhat from each other, which appears from the rough drawing. The pendulum rises in the extreme position IV by ca 24 cm, which also appears from the Figure drawn to the scale 1:10, and a controlled loop of the primary web is formed at the turning point. Owing to the smaller distance of the output end to the receiving conveyor S_A and the synchronization between the output rate and the oscillating rate of the output end, the fed out primary web is rapidly fixed to the web on the receiving conveyor, which also appears from the rough drawing. The motion of the pendulum from the point VII to I is the reverse image of the motion between the points I and VII, and is however not represented.
The left side of Figure 1 shows the case (B) in which the output end of the pendulum during the period of constant speed moves at a constant height above the receiving conveyor S_B, and during the period of retarded and accelerated motion moves along a circular path. In the mid-position of the pendulum, point VII, the oscillating point of the pendulum is at P′ but sinks to the point P during the drive motion up to point VIII, whereby the output end moves along a horizontal line. In the Figure no means is disclosed for guiding the pendulum axis P to P′ during the movement of the connecting rod end T from position VII to VIII. During the retardation phase from point VIII to X and the acceleration phase from point X to XII, the oscillating point P is kept stationary and the output end describes a circular arc. As appears from the Figure, the receiving conveyor S_B us situated higher than in case A, because the oscillating point of the pendulum is placed higher in the mid-position in case B.
The pendulum rises in its extreme position by ca 16 cm, which appears from the Figure. The looping is well controlled also in this case due to the short distance of the primary web to the bed particularly over the distances VII-VIII and XII-I and to the synchronization between the output rate and the oscillating rate of the output end over these distances.
In order to make the output end of the pendulum move horizontally during a major part, in the shown case 50% of the pendulum swing, whereby the oscillating point must move between P′ and P, special measures are required. Two preferred embodiments of such arrangements are shown in Figures 2 and 3.
Figures 2 and 3 show the pendulum part of a machine for producing mineral wool web and the associated drive mechanism. The receiving conveyor of the primary web is marked with 1, the associated pendulum conveyor with 2, the two opposite conveyors of the pendulum with 2a and 2b and conducting rollers in the output end with 3a and 3b. The receiving conveyor is marked with 4, the drive mechanism with 5, the two wheels of the drive mechanism with 5a and 5b and the connecting rod with 6. The parts 1 to 6 correspond mutually in the Figures 2 and 3 and have thus been marked with the same numbers.
In Figure 2, the wheel that conducts the pendulum motion in a guide device has been marked with 7 and the axis of the wheel fixed on the pendulum conveyor with 7a. The guide along which the wheel 7 has been arranged to run and which determines the feeding path of the output end has been marked with 9. The output end of the pendulum conveyor has been marked with 10.
When producing a mineral wool web, the primary web is fed out on its receiving conveyor 1 and runs further between the conveyors 2a and 2b into the pendulum mechanism 2, and is fed out at the output end 10. The pendulum swings to and fro while the primary web is being fed out between the conducting rollers 3a and 3b. As the connecting rod moves between the drive wheels 5a and 5b, the distance b₁, the wheel 7 has a constant rate of motion and simultaneously moves over the plane portion of the guide 9, whereby the conducting rolls 3a and 3b cover the distance B₁ at a constant height above the receiving conveyor. As the connecting rod moves along the circumference of the drive wheels, equalling the distances b₂, the wheel 7 moves over the upwardly bent end of the guide 9, whereby the output end of the pendulum describes a corresponding arched path over the distance B₂. The curvature of the guide 9 and its length in relation to the horizontal moving distance are determined by the desired kinematic geometry. In Figure 2, the starting point of the curvature of the guide coincides with the point where the moving speed of the connecting rod 6 changes from constant speed to decreased speed. This can be read from Figure 2, where the end T of the connecting rod is in position II, see Figure 1, where the constant speed of the pendulum changes to a decreased speed, at the same time as the wheel 7 is at the point where the horizontal part of the guide becomes arcuated. This is only a coincidence. It is not necessary that the horizontal movement of the wheel 7 coincides with the movement with a constant speed. The oscillating point 22 of the pendulum is displaceable along the line of the midline at the pendulum motion and the receiving conveyor 1 of the primary web is pivotally mounted in order to be able to follow vertically the motion of the input end of the pendulum.
Figure 3 shows another preferred embodiment of the device of the invention. The lower end of an arm 20 is pivotally fixed outside the pendulum on the midline of the oscillating motion, and its upper end is mounted on forkbearings to the bearing point 8 of the connecting rod 6 on the pendulum. The bearing point 8 is disposed to move in the fork 21 at the upper end of the arm. The oscillating point 22 of the pendulum is vertically displaceable along the midline of the motion and the receiving conveyor 1 of the primary web is pivotally mounted on bearings by articulation in order to be able to follow the movements of the pendulum vertically, likewise as in the preceding case. As the connecting rod moves over the horizontal area between the drive wheels the pendulum is drawn into an angular position while the oscillating point moves downwards until it reaches a stop 23 at the end of the constant speed period. The stop limits the vertical movement of the oscillating axis further upwards and the pendulum is forced to swing around the oscillating point P fixed by now. During this retarding part of the motion the connection point 8 between the connecting rod 6 and said arm 20 is displaced upwards in the fork 21 and thus does not prevent the pendulum from rising along an arched line. During the subsequent acceleration phase the pendulum swings down and the output end 10 describes the same arched line, while the connection point 8 is simultaneously displaced towards the bottom of the fork 21. The same motion is repeated in the opposite direction.
It is advantageous to dispose a spring between the central axis and the arm 20 to pick up part of the retardation and acceleration forces generated by the oscillation of the pendulum.
The embodiments of Figures 2 and 3 each show a pendulum motion composed so that the horizontal or essentially horizontal output motion coincides with the phase having a constant speed and the rising or sinking motion coincides with the phase having retarded or accelerated speed. The controlled feeding path of the output end, deviating from the natural arcuate feeding path, as disclosed in Figure 1(A), may of course be adjusted to start at any point during the period of constant speed b₁ or the period of retarding or accelerating motion b₂, as described above.
In Figure 1 the width of the mineral wool web as fed on to the receiving conveyor is marked with W. In Figure 2 the projections of the movement distances B₁ and B₂ of the output end 10 of the pendulum conveyor are marked with B_1P and B_2P respectively. The total pendulum stroke, which is called pendulum width B, is composed of the partial projections B_2P, B_1P and B_2P.
As stated above, the retardation and acceleration forces are less than in prior used methods, partly due to the rising motion at the sides of the output and partly due to a smaller pendulum having less mass.
It is obvious that a person skilled in the art is able to accomplish the inventive idea of a pendulum motion rising in the extreme positions, having a constant rate of motion in the central phase of the pendulum swing, in several different manners in addition to the embodiments described above.

Claims

1. A method of feeding a thin binder impregnated uncured primary web of mineral wool in zig-zag formation on a receiving conveyor (4) by means of a pendulum conveyor (2) arranged above the receiving conveyor, said pendulum conveyor swinging in a plane perpendicular to the direction of motion of said receiving conveyor, wherein
the speed of the receiving conveyor is lower than the speed at which the primary web is fed,
the swinging movement of the pendulum conveyor (2) is given a constant speed in the middle of the swinging movement and a retarding and an accelerating speed, respectively, in the end parts of the swinging movement, and
the output end (10) of the pendulum conveyor, before changing the direction of the pendulum movement, is raised in relation to the receiving conveyor (4) and after turning, during mainly the same part of the returning stroke, is respectively lowered,
characterized in that the output end (10) of the pendulum conveyor covers at least 30% and at most 60%, preferably 50%, of the pendulum stroke during the movement with a constant speed, and
that the constant speed is mainly the same as the feeding speed of the primary web.

2. Method according to claim 1, characterized in that the output end (10) of the pendulum conveyor moves at a constant height above the receiving conveyor (4) during at least part of, preferably during the whole of, the movement of the pendulum conveyor with constant speed.

3. Method according to either of claims 1 and 2, characterized in that raising and lowering of the output end (10) of the pendulum conveyor occurs along an arcuate, preferably an arcuate circular, path.

4. Method according to either of claims 1 and 2, characterized in that the moving path of the output end (10) of the pendulum conveyor is determined by a guide.

5. A device for feeding a thin binder impregnated uncured primary web of mineral wool in zig-zag formation on to a receiving conveyor (4), comprising:
a pendulum conveyor (2) arranged above the receiving conveyor (4) and swinging in the vertical plane, perpendicular to the movement direction of the receiving conveyor, the primary web being fed from the lower end (10) of the pendulum conveyor on to the receiving conveyor, the movement speed of which is lower than the feeding speed of the primary web, whereby the primary web is deposited on the receiving conveyor in overlapping pleats, thus forming a secondary web of desired thickness,
pendulum driving means (D;5) consisting of a connecting rod (6) associated at one end to the pendulum conveyor (2) and at the other end to an endless drive chain running over two horizontally coplanar and interspaced chain wheels (5a,5b) of substantially the same size,
means for giving the output end (10) of the pendulum conveyor a rising motion during at least the final part of the pendulum stroke before its turning position and a sinking motion during the corresponding part of the pendulum stroke after the turning position,
characterized in that
the relation of the drive wheel (5a,5b) diameter and the distance (b1) between the drive wheels is arranged so that the motion of the connecting rod end (T) over one of the two horizontal parts (b1) of the drive chain path corresponds, in pendulum motion, to at least 30% and at most 60%, preferably 50%, of the whole pendulum stroke, thus giving a constant speed of movement for the output end (10) of the pendulum conveyor during the same part symmetrically in the middle of the stroke and
the rotation speed of the drive wheels (5a,5b) is arranged so that the constant speed of the output end of the pendulum conveyor in the middle of the stroke is essentially the same as the output speed of the primary web.

6. A device according to claim 5, characterized in that pendulum axis (22) of the pendulum conveyor (2) is arranged to be vertically adjustable to allow the output (10) end to move along a horizontal motion path.

7. A device according to claim 6, characterized in that the lower end of an oscillating arm (20) is fixed on bearings outside the pendulum on the central axis of the pendulum motion and its upper end is mounted on fork-bearings or other bearings on the pendulum conveyor (2) with such a freedom of motion that the pendulum conveyor may accomplish a complete oscillation regardless of the length of the arm (20).

8. A device according to claim 7, characterized in that a stop (23) is arranged to stop the vertical motion of the oscillating axis (22) when the pendulum conveyor (1) is passing into a free pendulum movement.

9. A device according to claim 8, characterized in that a wheel (7) or similar rolling or sliding element is arranged on the pendulum conveyor (2) so that when in contact with a guide device (9) and in the course of the pendulum movement it transmits to the output end (10) of the pendulum conveyor (2) the desired moving path.