A PROCESS AND DEVICE FOR FEEDING A THIN BINDER IMPREGNATED UNCURED PRIMARY WEB OF MINERAL WOOL ONTO A RECEIVING CONVEYOR

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: A process and device for feeding a thin binder impregnated un- cured primary web of mineral wool onto a receiving conveyor The present invention relates to a process for feeding a thin binder impregnated uncured mineral wool web on a receiving con¬ veyor 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 product that is as uniform and homogenous as possible, yielding higher insulation capacity. Moreover, it should be as elastic as possible at a low density, requiring the fibres to be extended mainly in the sheet plane. Due to the elasticity, the sheet may compressed for the packing and transport step. in order to achieve this, a thin primary web, of which the basis 2 weight varies in the range of 110 to 450 g/m , preferably 100 to 200 g/m is collected on a collecting conveyor immediately after the defibration. The thinner the primary web, the better the quality of the finished product. In order to keep the capaci on the desired level while producing a thin primary web, the spe of the primary web as well as that of its conveying devices has be high. Normally, the speed of the primary web is over 100 m/mi however, the basis weight of the primary web being only in the 2 range of 100 to 200 g/m , an even higher speed is required in order to keep the capacity on the desired level . Various methods of folding mineral wool webs are described in th US patent specification 2 450 916 from 1948 and the somewhat younger GB patent specification 772 628, among others. These hav subsequently been completed with methods of folding the primary web by means of pendulum conveyors. When pendulum conveyors are being used for the feeding out of pri mary web, it is critical that the speed of the output end is abou the same as that of the primary web, in order to avoid folding or stretching of the web at the output moment. Up till now, the pendulum mechanism usually has comprised an ope¬ ration, in which the extreme positions have been highest above the receiving conveyor, and the lower dead point of the pendulum has been closest to the receiving conveyor. In order to achieve the desired capacity with the thin primary webs, the out¬ put rate of the pendulum conveyors should increase, however this is not feasible with known devices. In fact, a high speed pendu¬ lum 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 by a connecting rod and oscil¬ lating along a circular arc imparts a speed to the output end of the conveyor that is maximal when the pendulum is in the central position and decreases sinusoidally to zero in the extreme posi¬ tion, from where a sinusoidal acceleration reoccurs. The output end of such a pendulum conveyor must, in its lowest position, be disposed c. 0,2 times the output width, which normally is 2 , above the fed out wool web, in order to allow the primary web to be deposited in an uniform layer on the receiving conveyor withou being stretched. The distance between the pendulum and the receiv ing conveyor being that long up to 40 cm and more, the fed out web will get uneven edges. The output rate being c. 130 m/min, the irregularities of the secondary web formed will be c. +/- 5% of the output width. This signifies that the secondary web must b imparted a correspondingly larger width in order 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 car¬ ried out by continuously feeding out the primary web at a constan height above the support, at a constant height, are also known. A articulation system for maintaining the output end of the pendul mechanism at a constant height above the receiving conveyor is provided, and the to and fro motion is obtained by a chain/con¬ necting rod-mechanism. The speed profile of the oscillating moti has a constant speed period in the middle and a sinoidal retarda tion and acceleration phase in each end position. The pendulum must be rapidly retarded and accelerated in the end positions fo the pendulum motion to correspond to the output amount of the primary web per unit of time, causing great strains in the mecha ical constructions. Consequently, the mechanism is appropriate only at output rates below c. 100 m/min. Another drawback of pendulum mechanisms aving a high pendulum frequency is constituted of the strong flows of air generated by the rapid back and fro motion of a pendulum mechanism having large surface. The air flows hamper the depositing of the thin primary web onto the bed. Prior known are thus pendulum mechanisms for feeding thin pri¬ mary webs in over-lapping layers on a receiving conveyor. However, they all present considerable drawbacks; the edges are uneven, causing great loss of material , the speeds are too low t fullfil the capacity requirement, the retardation and accelerati forces are strong, causing great mechanical stress in the con¬ structions; the problem of air flow jeopardizes the depositing o the primary web. The purpose of the present invention is to reduce or totally eliminate these drawbacks, and especially to obtain an exact out laying with even edges and a web with high homogeneity, and this has been achieved by providing a method and a device, of which t main characteristics are presented in claims 1 and 9. 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 respectively increasing speed in the extreme positions of the pendulum motion. The period having constant speed may be in the range of 30 to 60% of the entire pendulum swing. The constant speed of the pendulum in the central area equals totally or nearly totally the output rate of the primary web. This enab¬ les the pendulum to be disposed closer to the receiving surface, at about half of the distance allowed by conventional crank drive thus ensuring considerably better the deposit and the fixation of the primary web on the receiving conveyor. In areas outside the phase having a constant speed the pendulum is driven at a sinusoidal ly decreasing respectively increasing ra te, while the pendulum pursues its pendulum motion. At least during part of the motion at a decreasing respectively increa¬ sing 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 re spectively the acceleration phase, potential energy is stocked respectively discharged, resulting in less stress forces on the mechanism than those generated when the output end of the pendulu describes a horizontal path over the entire pendulum swing. The pendulum motion, consisting of a central portion having a constant speed and two extreme portions having retarding and ac¬ celerating speeds, is appropriately produced by means of an end¬ less 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 corres¬ ponds to the pendulum motion having retarding and accelerating speed. The pendulum motion consisting of a central portion having constant speed and two extreme portions having retarding and accelerating 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 pondulum may be guided to move along diffe rently shaped paths in the course of the pendulum motion. The mo simple embodiment is an arched trajectory, whereby the pendulum swings around a stationary point of bearing. In such an embodi¬ ment, the pendulum operates with great accuracy at output rates c. 200 m/min. This is allowed by the fact that the output end of the pendulum may strike very close to the receiving conveyor, an closest thereto at the midpoint of the total swing, whereby the fed out primary web may be immediately fixed into the underlying fed out 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 c. 0.1 times the output width i.e. appr. 20 cm with an output width of 200 cm resulting in a more exact position for 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, c. 0.7 to 1.0 times the output width, i.e. c. 140 to 200 cm, which results in lower mass-moments of inertia and smaller stresses in the driving device. The air flow disturbances are also reduced b a shorter pendulum. In this embodiment, the pendulum may be adjusted to strike 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 havin very even edges. At a constant speed of above c. 50% of the out¬ put width, which is 200 cm, and a maximum pendulum swing of 80% and a pendulum length of c. 75% of the output width, i.e. 150 cm, the pendulum rises c. 12%, i.e. 24 cm, in the extreme positions. Another preferred embodiment of the invention is the one in which the pendulum and its output end are made to move horizontally at a constant height above the receiving conveyor in the central zo¬ ne 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, thus allowing for the primary web, which is fed out from the output end of the pendulum at a constan rate, enough space below the output end which then moves at a low er rate than the output rate of the primary web. The rising mo¬ tion 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, or at the latest at such a point before the extreme position of the pendulum swing, that enough space is allowed to be formed below the rising pendulum fo the accumulating loop to settle under control and to form an even edge during the reverse motion. The path described by the output end may be a linearly rising, circular, progressively arched line or various combinations of these . By means of various guide devices the pendulum or its output end is forced to deviate from the natural pendulum motion having a circular output path. From the moment there is a deviation from the natural pendulum motion, the oscillating point of the pendulu must be vertically movable or the swinging radius of the output end be variable. An output trajectory consisting of a mainly horizontal central portion and an arched end portion being desired, an arm mounted bearings in the pendulum may for instance comprise a lower end that is pivotally mounted on bearings outside the pendulum, thus forcing the pendulum to describe an essentially horizontal path. During this part of the motion the oscillating point of the pen¬ dulum sinks/rises. The oscillating point has been disposed so as to reach a stop or else stop in the position in which the pen dulum is to pass into a rising motion in the outmost zone of the pendulum swing respectively sinking motion in the same zone duri the reverse motion. The mounting of the arm on bearings in the pendulum is disposed so as to enable the pendulum to oscillate with regard to the arm at this stage, e.g. be means of fork bear ings. A spring may appropriately be disposed between the connec¬ ting rod top of the pendulum and the arm guiding the height posi tion of the pendulum, whereby the acceleration and retardation forces are partly equilibrated in the extreme positions of the pendul urn. The motion of the pendulum may also be guided by for instance a fixed guide disposed symmetrically with regard to the central axis along which a wheel mounted on bearings in the pendulum or sliding body are disposed to move. The trajectory of the output end will then correspond to the shape of the guide. The height o the guide above the ouptut end is determined by the optimization of geometry and mass forces. The oscillating point of the pendulum may alternatively be sta¬ tionary 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 presents a schematical representation of the pendulum motion of two preferred embodiments; the motion of the pendulum at a constant speed and subsequently at a retarded and an accele¬ rated speed, while the output end of the pendulum describes a cir cular path (case A) respectively the motion of the pendulum at a constant speed and subsequently at a retarded and an accelerated speed while the output end during the constant speed phase moves at a constant height above the receiving conveyor and during the retardation respectively acceleration phase moves along an arched path (case B) , figure 2 shows a preferred embodiment of the pendulum including the associated driving devi.ce and the pendulum shown in three different positions, and figure 3 shows another preferred embodiment of the pendulum in¬ cluding the associated driving device and 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 in this case, and the output end describes a circular arc. The pendulum is driven by the guide device D by means of a chain having 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 . In the drive chain the points 1 to 12 have been mark- A ed, whereby the points 1 and 7 indicate the central position of the pendulum, the points 4 and 10 the extreme positions of the pendulum and the points 12 and 2 respectively 6 and 8 the limits of the area having a constant speed. When the point T of the connecting rod is in the position 1, the pendulum is suspended from the oscillating point P and the position of the output end i indicated by the number 1 (A). From 1 to 2 the connecting rod mo¬ ves at a constant speed and the output end describes a circular arc since the oscillating point P is stationary. From 2 to 4 the pendulum moves with retardation, changes the direction of motion at the point 4 and from 4 to 6 with acceleration, while the out- put end describes a rising respectively sinking circular arc fro the connecting rod 6 to 7 moves at a constant speed, while the ouput end describes a rising respectively a sinking circular arc Depending on the position of the fastening point K on the pen- A dulum with regard to the drive device D, more or less geometrica assymmetry is achieved, i.e. the points 3 and 5 respectively 2 a 6 deviate somewhat from each other, which appears from the rough drawing. The pendulum rises in the extreme position 4 c. 24 cm, which also appears from the figure drawn in the scale 1:10, and forms a controlled loop of the primary web at the turning point. Owing to the smaller distance of the output end to the receiving conveyor S and the synchronization between the output rate and the oscillating rate of the output end, the fed out primary web rapidly fixed to the bed, which also appears from the rough draw ing. The motion of the pendulum from the point 7 to 1 is the re¬ verse image of the motion between the points 1 and 7, however no 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 constant height above the receiving conveyor S and during the B period of retarded and accelerated motion moves along a circular path. In the central position of the pendulum, point 7, the oscil lating point of the pendulum is at ? ' but sinks to the point P during the drive motion up to point 8, whereby the output end mo¬ ves along a horizontal line. During the retardation phase from point 8 to 10 and the acceleration phase from point 10 to 12, th oscillating point P is kept stationary and the output end descri¬ bes a circular arc. As it appears from the figure, the receiving conveyor S. is situated higher than in case A, because the B oscillating point of the pendulum is higher placed in the central position in case B. The pendulum rises in its extreme position c. 16 cm, which appear from the figure. The looping is well controlled also in this case due to the short distance of the primary web to the bed particu- larly over the distances 7-8 and 12-1 and to the synchronization between the output rate and the oscillating rate of the output en over these distances. In order to make the output end of the pendulum move horizontally during a major part, in the shown cases 50% of the pendulum swing whereby the oscillating point must move from P ' to P, special measures are required. Two preferred embodiments of such arrange¬ ments 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 recei¬ ving conveyor of the primary web is marked with 1, the associated pendulum conveyor with 2, the two opposite conveyors with 2a and 2b and the conducting rollers in the output end with 3a and 3b. The receiving conveyor has been marked with -4, the drive mechanis 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 fi¬ xed on the pendulum conveyor with 7a. The guide along which the wheel 7 has been arranged to run and which determines the tra¬ jectory 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 b , the wheel 7 gains a constant rate of motion and simultaneously moves over the plane portion of the guide 9, whe¬ reby the conducting rolls 3a and 3b cover the distance B at a constant height above the receiving conveyor. As the connecting rod moves along the circumference of the drive wheels, equalling the distances b , the wheel 7 moves over the upwards bended end 2 of the guide 9, whereby the output end of the pendulum describes corresponding arched path over the distance B . The position of 2 the guide 9 is determined by the desired kinetic geometry. The oscillating point 22 of the pendulum is displacable along the li of the central pendulum motion and the receiving conveyor 1 of t primary web is mounted on bearings by articulation in order to b able to vertically follow the motion of the input end of the pendul urn. Figure 3 shows another preferred embodiment of the pendulum of t invention. The lower end of ^ an arm 20 is fixed on -bearings outsi de the pendulum on the central line of the oscillating motion, a its upper end is mounted on fork-bearings to the bearing point 8 of the connecting rod 6 on the pendulum. The bearing point 8 is disposed to run in the fork 21 at the upper end of the arm. The oscillating point 22 of the pendulum is vertically displacable along the central line of the motion and the receiving conveyor of the primary web is mounted on bearings by articulation in or¬ der to be able to follow the movements of the pendulum verticall likewise as in the preceding case. As the connecting rod moves over the horizontal area between the drive wheels the pendulum i drawn into an angular position while the oscillating point moves downwards until its reaches a stop 23 at the end of the constant speed period. The stop prevents the oscillating point from being further dispaced downwards and the pendulum is forced to swing around the oscillating point P fixed by now. During this retarding part of the motion the fastening point 8 is displaced upwards in the fork 21 and thus does not prevent the pendulum from rising along an arched line. During the subsequent accelera¬ tion phase the pendulum swings down and the output end 10 descri¬ bes the same arched line, while the fastening point 8 simulta¬ neously is 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 acceleratio 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 respectively sinking motion coincides with the phase havin retarded respectively accelerated speed. The controlled trajector of the output end, deviating from the arched trajectory, may of course be adjusted to start at any point during the period of constant speed b or the period of retarding or accelerating motion b . 2 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 ha¬ ving less mass. It is obvious that a person skilled in the art is able to accomp¬ lish the inventive idea of a pendulum motion rising in the extrem positions, having a constant rate of motion in the central phase of the pendulum swing, in several different manners in addition the embodiments described above.

Claims: C l a i ms 1. A method of folding laying of a thin binder impregnated uncured primary web of mineral wool onto a receiving conveyor (4 comprising a folding laying onto the receiving conveyor by means of a pendulum conveyor (2) oscillating in a plane that is perpen dicular to the direction of motion of the receiving conveyor, whereby the speed of the receiving conveyor is lower than the output rate of the primary web, so that this is deposited in ove lapping folds forming a secondary web having the desired thick¬ ness, characterized in that the output end (10) of the pendulum conveyor (2) is imparted a rate of motion which is constant duri at least 30% of the oscillating period and equal or close to the output rate of the primary web, whereas the rest of the oscilla¬ ting period is constituted of a motion having retarding respecti vely accelerating speed and in that the output end (10) of the pendulum conveyor rises during at least part of the retardation period and sinks during essentially the corresponding ' part of th acceleration period of the reverse motion. 2. A method according to claim 1, characterized in that the pen¬ dulum conveyor (2) is imparted a constant rate of motion during 60% of the pendulum period at the most. 3. A method according to claim 1 or 2, characterized in that the output end (10) of the pendulum conveyor (2) starts rising already during the phase having constant speed and continues ri¬ sing during the entire retardation phase and sinks during the acceleration phase and the correspond ng part of the phase having constant speed during the reverse motion. 4. A method according to claim 1, characterized in that the out¬ put end (10) of the pendulum conveyor (2) describes an arched path, preferably a circular arc, during the entire pendulum mo¬ tion. 5. A method according to claim 1, characterized in that - the output end (10) of the pendulum conveyor (2) describes an es¬ sentially horizontal path until the moment it starts rising and from the moment it has sunk. 6. A method according to claim 5, characterized in that the output end (10) of the pendulum conveyor (2) describes an essen¬ tially horizontal path during the phase having constant speed and rises, preferably along an arched path, during the phase having retarding speed and in that it sinks, preferably along an arched path, during the acceleration phase and passes into an essentiall horizontal motion during the phase of the reverse motion having constant speed. 7. A method according to any of the preceding claims, characterized in that the pendulum conveyor (2) is oscillated by means of a chain drive (5) known per se and a connecting rod (6). 8. A method according to any of claims 1 to 6, characterized in that the pendulum conveyor is oscillated through a gear known per se, of which the output speed of rotation varies between a maximu and a minimum speed of rotation during each revolution. 9. A device for folding feeding of a thin binder impregnated un¬ cured primary web of mineral wool onto a receiving conveyor (4) comprising an essentially horizontal receiving conveyor (1) for the primary web and an associated pendulum conveyor (2) oscilla¬ ting in the vertical plane, from the lower end (10) of which the primary web is fed out onto an underlying receiving conveyor (4) whereby the pendulum conveyor oscillates in a plane that is per¬ pendicular to the direction of motion of the receiving conveyor (4), and the rate of motion of the recieving conveyor (4) is low¬ er than the output rate of the primary web, so that the primary web is deposited in overlapping folds, forming a secondary web, characterized in that a connecting rod (6) is associated to the pendulum conveyor (2) at one end and at the other end to an end less drive chain known per se running over two horizontally cop lanar and interspaced chain wheels (5a, 5b) of essentially the same size, whereby the distance between the wheels and the wheel diameters are arranged so that the motion of the connecting rod top together with the driving chain over one of the two horizon¬ tal parts to at least 30 % of the pendulum swing, while the mo¬ tion of the connecting rod top together with the driving chain along the circumference of the wheels in the outer parts of the pendulum swing correspond to the remaining part of the pendulum swing, whereby the pendulum conveyor during said at least 30 % o the pendulum swing is given a constant speed and during the re¬ maining part of the swing is given a retarding speed before the extreme position of the pendulum swing and an accelerating speed after said extreme position during an essentially equally great part of the pendulum swing, and in that means is provided which gives the output end of the pendulum conveyor (2) a rising motio during at least a part of the pendulum swing before the extreme position and a sinking motion during an essentially equally big part after the extreme position. 10. A device according to claim 9, characterized in that pendulum axis (22) of the pendulum conveyor (2) is arranged to b vertically adjustable to allow the output (10) end to move along a horizontal motion path. 11. A device according to claim 10, characterized in that the lower end of an oscillating arm 20) is fixed on bearings out side 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 regard¬ less of the length of the arm (20). 12. A device according to claim 11, characterized in that a stop (23) is arranged to stop the vertical motion of the oscil¬ lating axis (22) when the pendulum conveyor (1) is passing into a free pendulum movement. 13. A device according to claim 9, 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 trans¬ mits to the output end (10) of the pendulum conveyor (2) the de¬ sired moving path.

Inventors: LAUREN HENNING JOHN EMIL, LAUREN, HENNING, JOHN, EMIL
Applicants: PARTEK AB, OY PARTEK AB
Application year: 1987
Main classification: B65H45
IPC codes: B65H45, D01G25, D04H1