The present invention generally relates to the technical field of producing mineral fiber plates. Mineral fibers generally comprise fibers such as rockwool fibers, glass fibers, etc. More precisely, the present invention relates to a novel technique of producing a mineral fiber web from which e.g. mineral fiber plates or products are cut. The mineral fiber plates produced in accordance with the present invention exhibit advantageous characteristics as to mechanical performance, such as modulus of elasticity and strength, low weight, reduced content of bonding agents, and good acoustic-insulating and thermal-insulating properties.

Non-woven mineral fiber webs are normally hitherto produced as homogeneous webs, i.e. webs in which the mineral fibers of which the mineral fiber web is composed, are generally orientated in a single predominant orientation which is determined by the orientation of the production line on which the mineral fiber web is produced and transmitted during the process of producing the mineral fiber web. The product made from a homogeneous mineral fiber web exhibits characteristics which are determined by the integrity of the mineral fiber web and which are to a high degree determined by the binding of the mineral fibers within the mineral fiber plate produced from the mineral fiber web, and further to a high degree determined by the density of the mineral fibers of the mineral fiber plate.

The advantageous characteristics of mineral fiber plates of a different structure have already been realized as techniques for the production of mineral fiber plates in which the mineral fibers are arranged in an overall orientation different from the orientation determined by the production line have been described, vide e.g. Published International Patent Applications, International Application No.

PCT/DK94/00027, No. PCT/DK94/00028, No. PCT/DK94/00029 and No.

PCT/DK95/00041. The above-mentioned International Application No.

PCT/DK95/00041 discloses a method of producing a mineral fiber web product by producing a first non-woven mineral fiber web containing mineral fiber webs predominantly arranged in a first longitudinal direction, the segments of the first mineral fiber web being arranged in a partly mutually overlapping relationship for producing a second non-woven mineral fiber web which contains mineral fibers generally transverse relative to one another. The second mineral fiber web is folded transversly for producing a third non-woven mineral fiber web providing internal crossings of the fibers in angles larger than OO and smaller than 900, such as angles of the order of 10-60°, preferably 20-50°.

The above-mentioned International Patent Applications, such as International Application No. PCT/DK94/00028 and International Application No.

PCT/DK94/00029 disclose techniques of producing a mineral fiber web having fibers generally perpendicular to the plane of the web, the perpendicular orientation of the fibers being achieved by processing a finished mineral fiber web.

The above-mentioned International Patent Application No. PCT/DK94/00027 discloses a composite mineral fiber web comprising two mutually bonded layers, one of which has its fibers arranged in a plane parallel to the plane of the mineral fiber web, and the other in a plane perpendicular to the mineral fiber web. The mineral fiber web having its fibers arranged in a plane perpendicular to the mineral fiber web is produced by transversal folding of the initial fiber web without any longitudinal, zig-zag overlapping of the fiber web.

An object of the present invention is to provide a novel method of producing a mineral fiber web from which mineral fiber plates may be cut, which method renders it possible in an online production plant to produce mineral fiber plates which are of a composite structure providing distinct advantages regarding mechanical performance and excellent acoustic and thermal-insulating properties of the fibers as compared to the prior art homogeneous mineral fiber-containing plates.

A particular advantage of the present invention relates to the novel mineral fiber product produced in accordance with the method according to the present in- vention which, as compared to prior art mineral fiber plates, provides a more homogeneous structure, resulting in an overall improvement of the mechanical performance and the thermal-insulating properties of the novel mineral fiber web as compared to the mineral fiber webs of the prior art.

A particular feature of the present invention relates to the fact that the novel mineral fiber plate according to the present invention and produced in accordance with the method according to the present invention is produceable from less mineral fibers or less material as compared to the prior art mineral fiber plate still providing the same properties as the prior art mineral fiber plate regarding mechanical strength and thermal-insulating properties, thus providing a more lightweight and less voluminous mineral fiber plate product as compared to the prior art mineral fiber plate product reducing transport, storage and handling costs.

The above object, the above advantage and the above feature together with numerous other objects, advantages and features which will be evident from the below detailed description of presently preferred embodiments of the invention are obtained by a method according to the present invention comprising the following steps: a) producing a first, non-woven mineral fiber web defining a first, longitudinal direction parallel with said first mineral fiber web, said first mineral fiber web containing mineral fibers predominantly arranged along said first, longitudinal direction and including a first curable bonding agent, b) processing said first mineral fiber web by corrugating said first mineral fiber web transversly relative to said first, longitudinal direction for rearranging said mineral fibers of said first mineral fiber web from said arrangement predominantly along said first, longitudinal direction into an arrangement predominantly perpendicular to said first mineral fiber web, and c) folding said first mineral web generally parallel with said longitudinal direction so as to produce a second, folded, non-woven mineral fiber web

including mineral fibers predominantly arranged perpendicular to said second, folded mineral fiber web.

It is to be realized that the term "folding" is to be considered a generic term including any procedural step involving folding a mineral fiber web or any step equivalent thereto producing a mineral fiber web composed of overlapping layers defining a structure similar to the structure of a folded mineral fiber web such as a mineral fiber web produced by arranging separate layers in partly overlapping relationship. Similarly, the term "folded" is to be considered a generic term defining a characteristic of the mineral fiber web in question in particular in relation to the arrangement of segments or separate layers of the mineral fiber web in partly overlapping relationship. According to numerous prior art references, the term "doubled" is used synonymous with the term "folded" as used in the present context for defining the characteristic of the mineral fiber web in question namely the presence of numerous partly overlapping layers or segments which partly overlapping layers or segments originate from a basic non-folded or non-doubled mineral fiber web from which the second mineral fiber web in question is produced.

The second, folded, non-woven mineral fiber web exhibits a superior homogeneity as compared to the mineral fiber plates of the prior art due to the combined processing and folding of the first mineral fiber web.

In the present context the term "corrugated" is to be construed as being different from the term "folded", as "corrugated" will refer to the formation of low-height undulations or corrugations on the mineral fiber web, whereas "folded" will refer to the partial superposition of mineral fiber web folds over the width of a conveyor belt.

The first mineral fiber web is preferably a mineral fiber web of a 2ow area weight, such as an area weight of 50-500 glum , e.g. 100-400 glum , such as 200-300 git2.

According to two alternative embodiments of the method according to the present invention said processing of said first mineral fiber web is carried out either separately and preceding said step c) of folding said first mineral fiber web or concomitantly to said step c).

The folding step c) may in any of the preceding alternative embodiments be followed by a further step of compacting and compressing said second, folded mineral fiber web. The compressing step may consist of height compression, transversal compression, longitudinal compression or any combination of the above-mentioned types of compression. Furthermore or alternatively, the step of compacting and compressing said second, folded mineral fiber web may be carried out in a simple process, in a plurality of processes and/or in one or more multi-step processes.

The complex step of compression comprising preferably separate or simultaneous height compression, transversal compression and/or longitudinal

compression substantially removes the deviation from perpendicularity of the mineral fibers, which deviation is acquired during the processes of corrugation and folding.

By performing one or more of the above-described compression steps, the mineral fiber web exposed to the compression step or steps is made more homogeneous, the result being an overall improvement of the mechanical per- formance as compared to a non-compressed mineral fiber web. At the same time, a specific type of compression can impart the mineral fiber web specific properties pertaining to density and compactness. Since the compression is performed on a continuous, corrugated and folded mineral fiber web, the continuity of the mineral fiber web provides the resulting mineral fiber product with mechanical characteristics which are superior to the characteristics of the mineral fiber plates of the prior art obtained by compression of adjacent segments, segmentation of the mineral fiber web being eliminated.

The above described embodiments of the method according to the present invention may further comprise the following additional steps: d) producing a third non-woven mineral fiber web defining a further direction parallel with said third mineral fiber web, said third mineral fiber web containing mineral fibers arranged generally in said further direction and including a second curable bonding agent, said third mineral fiber web being a mineral fiber web of a higher compactness as compared to said second mineral fiber web, e) adjoining said third mineral fiber web to said second folded mineral fiber web in facial contact therewith for producing a fourth composite mineral fiber web, and f) curing said first and second curable bonding agents so as to cause said mineral fibers of said fourth composite mineral fiber web to bond to one another.

According to a further alternative embodiment of the method according to the present invention, said third non-woven mineral fiber web may be produced by separating a top or a bottom surface segment layer of said first mineral fiber web therefrom prior to or after said strip b) of processing said first mineral fiber web and by compacting said surface segment layer for producing said third mineral fiber web.

A mineral fiber plate or product of a sandwich structure may be obtained by separating two opposite segment layers of said first mineral fiber web therefrom prior to or after said strip b) of processing said first mineral fiber web and by compacting said surface segment layers and the remaining core layer for producing said mineral fiber plate of a sandwich structure.

The above objects, the above advantages and the above features together with numerous other objects, advantages and features are furthermore obtained by means of a plant for producing a cured non-woven mineral fiber web, comprising: a) first means for producing a first non-woven mineral fiber web defining a first longitudinal direction parallel with said first mineral fiber web, said first

mineral fiber web containing mineral fibers predominantly arranged along said first, longitudinal direction and including a first curable bonding agent, b) second means for moving said first mineral fiber web in said first longitudinal direction of said first mineral fiber web, c) third means for processing said first mineral fiber web by corrugating said first mineral fiber web transversly relative to said first longitudinal direction for rearranging said mineral fibers of said first mineral fiber web from said arrangement predominantly along said first, longitudinal direction into an arrangement predominantly perpendicular to said first mineral fiber web, and d) fourth means for folding said first mineral fiber web generally parallel with said first longitudinal direction so as to form a second folded mineral fiber web including mineral fibers predominantly arranged perpendicular to said second, folded mineral fiber web.

The plant according to the present invention may advantageously comprise any of the above features of the method according to the present invention.

The above objects, the above advantages and the above features together with numerous other objects, advantages and features are furthermore obtained by means of a mineral fiber-insulating plate, comprising: a plurality of mutually parallel layers, each layer defining a plane slightly diverging from said product plane, and each layer including a meander like corrugated mineral fiber structure including mineral fibers predominantly arranged perpendicularly relative to said layers, and, said mineral fibers of said layers and said layers being bonded together in an integral structure solely through cured bonding agents cured in a single curing process and initially present in uncured, non-woven mineral fiber webs from which said layers are produced.

The mineral fiber-insulating plate according to the present invention may advantageously comprise any of the features discussed above with reference to the method according to the present invention and may further advantageously be produced in accordance with the method according to the present invention and/or by means of the plant according to the present invention.

In the following description similar elements have been assigned identical reference numerals, while similar elements having different functions have been assigned identical reference numerals but primed in accordance with the number of times the element is repeated in the description.

The present invention will now be further described with reference to the drawings, in which Fig. 1 is a schematic and perspective view illustrating a first production step of producing a mineral fiber web from a mineral fiber forming melt, Fig. 2 is a schematic and perspective view similar to the view of Fig. 1 illustrating a first production step of producing a mineral fiber web from a mineral fiber forming melt, which first production step is an alternative to the first production step illustrated in Fig. 1,

Fig. 3 is a schematic and perspective view illustrating a production step of height-compressing and longitudinally compressing a mineral fiber web, Fig. 4 is a schematic view illustrating an alternative technique of folding a mineral fiber web transversly relative to the longitudinal direction of the mineral fiber web, Fig. 5 is a schematic and perspective view illustrating a production step of separating a surface layer of the folded mineral fiber web produced in accordance with the techniques disclosed in Figs. 1-4, and a production step of compacting the surface layer, Fig. 6 is a schematic and perspective view illustrating a mineral fiber web produced in the production step shown in Fig. 1, Fig. 7 is a schematic and perspective view illustrating a production plant for the production of a mineral fiber web according to the present invention, and Fig. 8 is a schematic and perspective view illustrating in greater details a production step of the production of the mineral fiber web also illustrated in Fig.

7.

In Fig. 1, a first step of producing a mineral fiber web is disclosed. The first step involves the formation of mineral fibers from a mineral fiber forming melt which is produced in a furnace 10 and which is supplied from a spout 12 of the furnace 10 to a total of four rapidly rotating spinning-wheels 14 to which the mineral fiber forming melt is supplied as a mineral fiber forming melt stream 16. As the mineral fiber forming melt stream 16 is supplied to the spinning- wheels 14 in a radial direction relative thereto, a cooling gas stream is simul- taneously supplied to the rapidly rotating spinning-wheels 14 in the axial direction thereof causing the formation of individual mineral fibers which are expelled or sprayed from the rapidly rotating spinning-wheels 14 as indicated by the reference numeral 18. The mineral fiber spray 18 is collected on a continuously operated first conveyor belt 42 forming a primary mineral fiber web 40. A heat-curable bonding agent is also added to the primary mineral fiber web 40 either directly to the primary mineral fiber web 40 or at the stage of expelling the mineral fibers from the spinning-wheels 14, i.e. at the stage of forming the individual mineral fibers. The first conveyor belt 42 is, as is evident from Fig. 1, composed of two conveyor belt sections. A first conveyor belt section which is sloping relative to the horizontal direction and relative to a second, substantially horizontal conveyor belt section. The first section constitutes a collector section, whereas the second section constitutes a transport section by means of which the primary mineral fiber web 40 is transferred to a second and a third continuously operated conveyor belt designated the reference numeral 44 and 46, respectively, which are operated in synchronism with the first conveyor belt 42 sandwiching the primary mineral fiber web 40 between two adjacent surfaces of the second and third conveyor belts 44 and 46, respectively.

The two conveyor belts 44 and 46 are driven by a motor 20 and the primary mineral fiber web input to the two conveyor belts 44 and 46 is delivered to a fourth conveyor belt 48 as a corrugated, primary mineral fiber web 50, as will be explained in greater detail below. The fourth conveyor belt 48 constitutes a collector conveyor belt on which the corrugated primary mineral fiber web 50 is collected as the second and third conveyor belts 44 and 46, respectively, are swung across the upper surface of the fourth conveyor belt 48 in the transversal direction relative to the fourth conveyor belt 48. The swinging motion of the conveyor belts 44 and 46 creates a partial superposition of the mineral fiber web delivered from the second and third conveyor belts 44 and 46, respectively, to the fourth conveyor belt 48 and at the same time causes the mineral fiber web delivered from the second and third conveyor belts 44 and 46, respectively, to be corrugated, as illustrated in Fig. 1, as the speed of transportation of the first conveyor belt 42 and the second and third conveyor belts 44 and 46, respectively, as compared to the speed of swinging the conveyor belts 44 and 46 across the fourth conveyor belt 48, generates an accumulation of the mineral fiber web on the fourth conveyor belt 48, producing the corrugated, primary mineral fiber web 50 including low-height corrugations or ondulations. It is to be realized that the corrugated, primary mineral fiber web 50 may be produced in alternative ways, e.g. through decelerating sequentially the second and third conveyor belts 44 and 46, respectively, and/or oscillating vertically the second and third conveyor belts 44 and 46, respectively, relative to the fourth conveyor belt 48. Alternatively, the two conveyor belts 44 and 46 may be substituted by two sets of conveyor belt as each of the conveyor belts 44 and 46 may be substituted by an input conveyor belt and an output conveyor belt. The two input conveyor belts together constitute an input conveyor belt set operated in synchronism with the first conveyor belt 42, and the two output conveyor belts together constitute an output conveyor belt producing a deceleration and longitudinal compression of the primary mineral fiber web 40 and consequently a corrugation of the first mineral fiber web 40. Through the folding of the corrugated, primary mineral fiber web 50 in partially overlapping relationship a secondary, corrugated and folded mineral fiber web 70 is produced.

It is to be realized that the overall orientation of the corrugated mineral fibers is generally perpendicular to the fourth conveyor belt 48, the result being a secondary, corrugated and folded mineral fiber web 70 containing fibers being arranged predominantly perpendicularly to the direction of transportation of the fourth conveyor belt 48. Another particularity of the secondary mineral fiber web 70 is that it is more homogeneous than the primary mineral fiber web 40. It is to be mentioned that in the present specification the term "corrugation" or "undulation" is generally used to denominate the low-height elements of a wavy web structure, whereas the term "fold" is generally used to denominate overlapping or crosslapping sections of a greater size of any web structure.

In Fig. 2, mineral fibers are formed from a mineral fiber forming melt which is produced in a furnace 10 and which is supplied from a spout 12 of the furnace 10 to a total of four rapidly rotating spinning-wheels 14 to which the mineral fiber forming melt is supplied as a mineral fiber forming melt stream 16. As the mineral fiber forming melt stream 16 is supplied to the spinning-wheels 14 in a radial direction relative thereto, a cooling gas stream is simultaneously supplied

to the rapidly rotating spinning-wheels 14 in the axial direction thereof, causing the formation of individual mineral fibers which are expelled or sprayed from the rapidly rotating spinning-wheels 14, as indicated by the reference numeral 18. The mineral fiber spray 18 is collected on a continuously operated first conveyor belt 42 forming a primary mineral fiber web 40. A heat-curable bonding agent is also added to the primary mineral fiber web 40 either directly to the primary mineral fiber web 40 or at the stage of expelling the mineral fibers from the spinning-wheels 14, i.e. at the stage of forming the individual mineral fibers. When leaving the conveyor belt 42, the primary mineral fiber web 40 is passed through two intermittently operated actuator arms 126 and 126' which are intermittently brought into contact with the upper side surface and the lower side surface of the web 40. The construction of a conjoint actuator device comprising actuator cylinders 130, 130', articulated arms 128, 129, 128', 129' and actuator arms 126, 126' is described in greater detail in Fig. 4. The intermittent operation of the actuator arms 126 and 126' provides the primary mineral fiber web 40 with low-height undulations or corrugations producing the corrugated, primary mineral fiber web 50 which is subsequently passed through two sandwiching conveyor belts 44' and 46' which ensure that the undulations of the corrugated, primary mineral fiber web 50 are of equal height. At the exit from the sandwiching conveyor belts 44' and 46' the corrugated, primary mineral fiber web is folded transversly relative to the direction of transportation of a third conveyor belt 48 similar to the conveyor belt 48 described in connection with Fig. 1.

The result of the operation described in connection with Fig. 2 is, similarly to the result achieved by the operation described in connection with Fig. 1, that the secondary, corrugated and folded mineral fiber web 70 similar to the secondary, corrugated and folded mineral fiber web illustrated in Fig. 1 is obtained. The fiber orientation of the secondary, corrugated and folded mineral fiber web 70 illustrated in Fig. 2 is, similarly to the secondary, corrugated and folded mineral fiber web 70 illustrated in Fig. 1, predominantly perpendicular to the direction of transportation of the conveyor belt 48.

In Fig. 3, a station for compacting and homogenizing an input mineral fiber web 70 is shown, which station serves the purpose of compacting and homogenizing the input mineral fiber web 70 for producing an output mineral fiber web 70', which output mineral fiber web 70' is more compact and more homogeneous as compared to the input mineral fiber web 70. The input mineral fiber web 70 may constitute the secondary mineral fiber web 70 produced in the station shown in Fig. 1 or the secondary mineral fiber web 70 produced in the station shown in Fig. 2. Alternatively, the input mineral fiber web 70 shown in Fig. 3 may be substituted by the primary mineral fiber web 40 shown in Figs. 1 or 2.

The compacting station comprises two sections. The first section comprises two conveyor belts 52" and 54", which are arranged at the upper side surface and the lower side surface, respectively, of the mineral fiber web 70. The first section basically constitutes a section in which the mineral fiber web 70 input to the section is exposed to height compression, causing a reduction of the overall height of the mineral fiber web and a compacting of the mineral fiber web. The conveyor belts 52" and 54" are consequently arranged in a manner in which they

slope from an input end at the left-hand side of Fig. 3, at which input end the mineral fiber web 70 is input to the first section, towards an output end from which the height-compressed mineral fiber web is delivered to the second section of the compacting station.

The second section of the compacting station comprises three sets of rollers 56' and 58', 56" and 58", and 56"' and 58"'. The rollers 56', 56" and 56"' are arranged at the upper side surface of the mineral fiber web, whereas the rollers 58', 58" and 58"' are arranged at the lower side surface of the mineral fiber web. The second section of the compacting station provides a longitudinal compression of the mineral fiber web, which longitudinal compression produces a homogenization of the mineral fiber web, as the mineral fibers of the mineral fiber web are caused to be rearranged as compared to the initial structure into a more homogeneous structure. The three sets of rollers 56' and 58', 56" and 58", and 56"' and 58"' of the second section are rotated at the same rotational speed, which is, however, lower than the rotational speed of the conveyor belts 52" and 54" of the first section, causing the longitudinal compression of the mineral fiber web. The height-compressed and longitudinally compressed mine- ral fiber web is output from the compacting station shown in Fig. 3, designated the reference numeral 70'.

It is to be realized that the combined height- and longitudinal compression compacting station shown in Fig. 3 may be modified by the omission of one of the two sections, i.e. the first section constituting the height-compression section, or alternatively the second section constituting the longitudinal- compression section. By the omission of one of the two sections of the compacting station shown in Fig. 3, a compacting section performing a single compacting or compression operation is provided, such as a height-compressing station or alternatively a longitudinally-compressing station. Although the height-compressing section has been described including conveyor belts, and the longitudinally-compressing section has been described including rollers, both sections may be implemented by means of belts or rollers. Also, the height- compressing section may be implemented by means of rollers, and the longitudinally-compressing section may be implemented by means of conveyor belts.

In Fig. 4, the alternative technique illustrated in Fig. 2 of folding a mineral fiber web in the transversal direction of the mineral fiber web is illustrated in greater detail. In Fig. 4, the mineral fiber web 40 may alternatively constitute the output mineral fiber web 70' shown in Fig. 3, or alternatively the mineral fiber web 70 produced in the station shown in Fig. 1 or the mineral fiber web 70 produced in the station shown in Fig. 2. The mineral fiber web 40 is folded transversly as the mineral fiber web 40 is output from two sandwiching conveyor belts 120' and 120" and folded by means of the actuator arms 126 and 126' which are intermittently brought into contact with the upper side surface and lower side surface, respectively, of the web 70'. As one of the actuator arms 126 and 126' maintains the folded mineral fiber web in position within two sandwiching conveyor belts 122' and 122", the other actuator arm is brought into contact with the respective side surface of the web 40 and folds the web 40 transversly relative to the longitudinal direction of the web 40. The actuator

arms 126 and 126' are supported on articulate arms 128, 129 and 128', 129', respectively, which articulate arms 128, 129 and 128', 129' are actuated by means of actuator cylinders 130 and 130', respectively. The transversly folded mineral fiber web produced by means of the production station shown in Fig. 4 and output from the sandwiching conveyor belts 122' and 122" is designated the reference numeral 50.

Fig. 5 is a schematic and perspective view illustrating a production step of separating a surface layer 24 from a core 28 of the corrugated mineral fiber web 50 produced in accordance with the techniques disclosed in Figs. 1-4, and a production step of compacting the surface layer 24.

The mineral fiber web 50 shown in Fig. 5 and produced in accordance with the techniques discussed above with reference to Figs. 1-4 is further processed in a station illustrated in Fig. 5, in which station the surface layer 24 is separated from the central core or body 28 of the corrugated and longitudinally folded mineral fiber web 50. The separation of the surface layer 24 from the core 28 of the mineral fiber web 50 is accomplished by means of a cutting tool 72 as the core 28 is supported and transported by means of a conveyor belt 170. The cutting tool 72 may be constituted by a stationary cutting tool or knife or alternatively be constituted by a transversly reciprocating cutting tool or further alternatively be constituted by a band saw. The surface layer 24 separated from the mineral fiber web is derived from the path of travel of the remaining part of the mineral fiber web by means of a conveyor belt 74 and is transferred from the conveyor belt 74 to three sets of rollers comprising a first set of rollers 76' and 78', a second set of rollers 76" and 78", and a third set of rollers 76"' and 78"', which three sets of rollers together constitute a compacting or com- pressing section similar to the second section of the corresponding station described above with reference to Fig. 3.

Further it is to be mentioned that the secondary mineral fiber web 50 may be further processed according to the techniques described in Applicant's International Patent Applications No. PCT/DK94/00027, PCT/DK94/00028, PCT/DK94/00029 and PCT/DK95/00041.

Fig. 6 is a schematic and perspective view illustrating a mineral fiber web 1 produced in the production step shown in Fig. 1 or, alternatively, Fig. 2. The mineral fiber web 1 shown in Fig. 16 is produced from the secondary, corrugated and folded mineral fiber web 70 shown in Figs. 1 and 2 and it comprises meandering web layers la, lb, lc, ld, etc. continuing into each other such that the left side of layer la is connected to the left side of layer lb, the right side of layer 1b is connected to the right side of layer lc, and so on to the bottom layer. In Fig. 16 the arrow a indicates the direction of transportation of the conveyor 48 illustrated in Fig. 1 or, alternatively, in Fig. 2.

Fig. 7 is a schematic and perspective view illustrating a further embodiment of a production plant for the production of a mineral fiber web according to the present invention. In the upper left hand part of Fig. 7, a first station for carrying out a first step of producing a mineral fiber web is disclosed. The first step involves the formation of mineral fibers from a mineral fiber forming melt

which is produced in a furnace 10 and which is supplied to a spout 12 of the furnace 10 to one or more rapidly rotating spinning wheels 14 to which the mineral fiber forming web is supplied as a mineral fiber forming melt stream 16.

As a mineral fiber forming melt stream 16 is supplied to the spinning wheel or wheels 14 in a radial direction relative thereto, a cooling gas stream is simultaneously supplied to the rapidly rotating spinning wheel or wheels 14 in the axial direction thereof causing the formation of individual mineral fibers 18 which are expelled or sprayed from the rotating spinning wheel or wheels 14.

The mineral fiber spray 18 is collected on a continuously operated first conveyor belt 19 and forms a primary mineral fiber web 20 which is transferred from the first conveyor belt 19 to a second conveyor belt 23. A heat hardening or heat curable bonding agent is also added to the primary mineral fiber web 20 either directly thereto or at the stage of expelling the mineral fibers from the spinning wheel or wheels 14, i.e. at the stage of forming the individual mineral fibers 18.

The first conveyor belt 19 is sloping relative to the horizontal direction and relative to the second conveyor belt 23 which is arranged substantially horizontally. The first conveyor belt 19 constitutes a collector conveyor belt, whereas the second conveyor belt 23 constitutes a transport conveyor belt.

From the second conveyor belt 23, the primary mineral fiber web 20 is transferred to a second station designated the reference numeral 25 in its entirety. The station 25 constitutes a station in which the overall direction of transportation of the primary mineral fiber web 20 is transformed from the longitudinal direction defined by the first and second conveyor belts 19 and 23, respectively, to a longitudinal direction determined by a mineral fiber web 40.

The mineral fiber web 40 constitutes a mineral fiber web from which the mineral fiber products are produced in accordance with the teachings of the present invention as will be evident from the below description. The mineral fiber web 40 is a mineral fiber web originating from a directly collected primary mineral fiber web 20 and consequently contains mineral fibers predominantly ar- ranged or oriented in the longitudinal direction of the mineral fiber web 40.

Thus, the mineral fiber web 40 defines a first longitudinal direction and a first transversal direction, the first longitudinal direction being the direction along which the mineral fibers of the mineral fiber web 40 is predominantly arranged or oriented.

The mineral fiber web 40 is transferred from the station 25 by means of conveyor belts, not shown in Fig. 7, to a roller 27 which serves the purpose of shifting the direction of transportation of the mineral fiber web 40 from a substantially horizontal direction to a substantially vertical direction as indicated by an arrow 29 for the transfer of the mineral fiber web 40 to a further station in which the mineral fiber web 40 is transformed into a segmentary mineral fiber web 70" by arranging segments of the mineral fiber web 40 in partly mutually overlapping relationship and transversly relative to the longitudinal direction and the transversal direction of the segmentary mineral fiber web 70" for the formation of the segmentary mineral fiber web 70" and at the same time corrugating the individual segments. The transformation of the mineral fiber web 40 into the segmentary mineral fiber web 70" is accomplished by means of two pendulum conveyor belts 44 and 46 having upper input ends to which the mineral fiber web 40 is input and lower output ends from which the mineral

fiber web 40 input to the two pendulum conveyor belts 44 and 46 is output as a corrugated mineral fiber web 50" defining segments which are arranged in the above-described partly overlapping relationship in accordance with the technique described above with reference to Fig. 1 for the formation of the segmentary mineral fiber web 70" being a corrugated mineral fiber web.

In Fig. 7, two segments designated the reference numerals 33 and 41, re- spectively, are shown constituting segments of which the segmentary mineral- fiber web 70" is composed. The corrugated segment 41 is defined by opposite folds 35 and 37 connecting the corrugated segment 41 to a previously produced corrugated segment and to the corrugated segment 33, respectively. The corrugated segment 33 is further defined by a fold 31 through which the corrugated segment is connected to the mineral fiber web 50" extending substantially vertically to the pendulum conveyors 44 and 46. The segmentary mineral fiber web 70" is moved from a position below the pendulum conveyor belts 44 and 46 to the right in Fig. 7 towards a further processing station 65 comprising two height compressing or compacting conveyor belts 67 and 69 which serve the purpose of compacting and homogenizing the segmentary mineral fiber web 70". In Fig. 7, the reference numeral 39 designates a front edge of the corrugated segment 33 which front edge constitutes a boundary line between the corrugated segments 33 and 41 of the segmentary mineral fiber web 70".

It is to be realized that the segmentary mineral fiber web 70" is composed of corrugated segments originating from the mineral fiber web 40 in which the mineral fibers are predominantly arranged or oriented along the longitudinal direction of the mineral fiber web 40 and the mineral fibers of the segmentary mineral fiber web 70" are consequently predominantly arranged or oriented in directions determined by the position of the corrugations of the individual segments of the segmentary mineral fiber web 70" such as the segments 33 and 41. The transverse directions along which the mineral fibers of the segmentary mineral fiber web 70" are arranged are basically defined by the ratio between the speed of transportation of the mineral fiber web 40 and the speed of transportation of the segmentary mineral fiber web 70", i.e. the ratio between the speed of transportation of the conveyor belt by means of which the mineral fiber web 40 is fed to the pendulum conveyors 44 and 46 and the speed of transportation of the conveyor belt by means of which the segmentary mineral fiber web is transferred from the pendulum conveyor belts 44 and 46 towards the station 65. Through the alternation of the ration between the above described speeds of transportation of the mineral fiber 40 and the segmentary mineral fiber web 70", the partly mutually overlapping relationship of the segments of the corrugated, segmentary mineral fiber web 50 is adjustable as well as the overall orientation of the mineral fibers of the segmentary mineral fiber web 70" along the transverse directions along which the mineral fibers of the segmentary mineral fiber web 70" are predominantly arranged or oriented.

The conveyor belts 67 and 69 of the height compressing or compacting station 65 are of a wedge-shaped configuration providing a compression of the segmentary mineral fiber web 70" at least at the output end of the compacting station 65 and are operated so as to cause a vertical pendulum motion of the

segmentary mineral fiber web 70" at the output end of the compacting station 65. Consequently, the compacting station 65 causes an overall homogenization through rearrangement of mineral fibers producing a homogeneous mineral fiber web which is output from the compacting station 65 in a vertical pendulum motion to a further processing station 71 in which the mineral fiber web is further processed for the formation of a corrugated mineral fiber web.

In the processing station 71, the mineral fiber web output from the compacting station 65 is corrugated for the formation of a mineral fiber web in which the mineral fiber web output from the compacting station 65 is corrugated vertically and consequently transversly or perpendicularly relative to the longitudinal direction of the mineral fiber web and parallel with the transversal direction of the mineral fiber web. The corrugated mineral fiber web is produced by means of two conveyor belts 73 and 75 sandwiching the mineral fiber web and providing a further deceleration of the rate of transportation of the mineral fiber web into the compacting station and consequently a vertical corrugation of the mineral fiber web.

From the station 71, the vertically corrugated mineral fiber web is input to a further station 72 comprising two conveyor belts 79 and 81 which further decelerates the speed of transportation of the mineral fiber web 70" for the formation of a compacted and homogenized mineral fiber web 70"'. The mineral fiber web 70"' constitutes a final product which may further be processed, as will be described below, for the formation of the specific mineral fiber products such as insulating plates or composite products.

In Fig. 8, the segmentary fiber web 50", which further constitutes a corrugated and folded mineral fiber web 50 is shown in greater detail illustrating the segments 33 and 41 and further the edges 37 and 31. Fig. 8 further illustrates in greater details the predominant arrangement or orientation of the mineral fibers of the individual segments of which the segmentary, corrugated mineral fiber web 50" is composed. The corrugated mineral fiber web 50" is provided with undulations or corrugations 45 predominantly perpendicular to the fiber web 50 surface, which undulations, together with the transversal orientation of the folds 33, 41, etc., ensure the resulting corrugated mineral fiber 50 an orientation of the fibers perpendicular to the fiber web 50 and, consequently, improved insulating properties in comparison with fiber webs of the prior art.

The mineral fiber webs produced in accordance with the teachings of the present invention constituting corrugated and folded mineral fiber webs may be used for producing thermal or acoustic insulating products or alternatively or additionally used for producing horticultural products or any equivalent or similar mineral fiber products.

In the above description, specific conveyor belts, rollers etc. have been described with reference to the drawings. It is, however, to be realized that a specific operation described with reference to a specific element such as a conveyor belt in numerous instances may be substituted by two or more conveyor belts or sets of rollers and also that certain rollers may be substituted by a conveyor belt or two or more conveyor belts. Modifications of the above kind of substituting conveyor belts by rollers and vice versa and combining conveyor belts into a single conveyor belt or dividing a single conveyor belt into two or more conveyor belts are considered obvious to a person skilled in the art and to be considered part of the present invention as defined in the appending claims.