| Title of Invention | APPARATUS FOR THE MANUFACTURE OF A SPUNBOND WEB |
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| Abstract | An apparatus for the manufacture of a spunbond web, having a foraminous deposition belt, onto which the fibers for the spunbond web can be deposited. The foraminous deposition belt is spanned over at least one roller, and the roller surface of the roller is profiled such that the foraminous deposition belt is in contact only with high spots of the roller surface. |
| Full Text | Description: The invention relates to an apparatus for the manufacture of a spunbond web, having a foraminous deposition belt onto which fibers for the spunbond web can be deposited. The fibers are particularly made of thermoplastic synthetic resin, and preferably fibers, or continuous filaments made of thermoplastic synthetic resin. Generally and preferably, a suction device is provided under the foraminous deposition belt to suction air down through the foraminous deposition belt in the area where the fibers are deposited. An apparatus of the type described above is known in practice in various embodiments. The foraminous deposition belt is usually guided over several rollers so that there is substantial contact between the roller surfaces and the deposition belt. Once the fibers are deposited on the foraminous deposition belt, some of them are sucked through the foraminous deposition belt, e.g. between the warp and weft of the foraminous deposition belt. These are termed "throughshots." The known apparatus has in the transfer area of the spunbond web an output roller that normally is spanned over the deposition belt over a relatively large angle. In this output area, the spunbond web is usually transferred from the deposition belt to a calender in which the spunbond web is compacted. As a result of the corresponding continued movement of the spunbond web, the pinched fibers are torn off, and the torn-off fibers are freed to go into the air as fiber waste (so-called "snow"). The fibers remaining between the warp and weft threads of the foraminous deposition belt are pressed into and onto the foraminous deposition belt due to the interaction of the foraminous deposition belt with the rollers of the apparatus, thus forming undesired adhesion points for the spunbond web on the foraminous deposition belt. This contamination of the deposition belt has an adverse effect on the quality of the spun non-woven materials produced. In contrast, the object of invention is to provide an apparatus of the type mentioned above that avoids the previously mentioned disadvantages, and by means of which particularly the undesired fiber waste, or "snow," and the undesired contamination of the deposition belt can be prevented. In order to attain this object, the invention teaches an apparatus for the manufacture of a spunbond web, having a foraminous deposition belt, onto which fibers for the spunbond web can be deposited, wherein the foraminous deposition belt is guided across a roller, and the roller surface of the roller is profiled to have high spots such that the foraminous deposition belt is in moving contact only with the high spots of the roller surface. The invention provides for the deposition of fibers/filaments made of thermoplastic synthetic resin onto the foraminous deposition belt. According to one embodiment the fibers are continuous filaments. Preferably, the fibers/filaments are cooled and stretched, or aerodynamically stretched before they are deposited on the foraminous deposition belt. Advantageously, the fibers/filaments are guided through at least one diffuser before they are deposited on the foraminous deposition belt. Due to the shape of the roller surface according to the invention, high spots and low spots are present on the roller surface of the roller. The foraminous deposition belt is in contact only with partial areas of this roller surface, namely with the high spots. The foraminous deposition belt is generally guided across multiple rollers, or drive rollers, respectively. According to a very preferred embodiment having particularly great meaning to the invention, the profiled roller according to the invention is the output roller for the spunbond web. In this context, an output roller means that the spunbond web that is moved across the output roller is transferred in a travel direction downstream of the output roller to a processing device for the spunbond web, or to a further conveyor device (conveyor belt, deposition belt, or such). According to a very preferred embodiment of the invention the output roller surface of the output roller is also profiled, or equipped with the high spots and low spots. Advantageously, the output roller is simultaneously a drive roller for the drive of the foraminous deposition belt. According to a particularly preferred embodiment of the invention the profiled roller, or the profiled output roller serves for output of the spunbond web to a calendar. Advantageously, the spunbond web subsequent to the movement across the output roller in the travel direction is therefore pulled by a calendar, or between two calendar rollers of a calendar downstream from the output roller. The invention provides that the foraminous deposition belt is spanned over the roller, preferably the output roller, through an angle of at least 70°, preferably of at least 90°, and most preferably of at least 120°. According to a particularly preferred embodiment of the invention the foraminous deposition belt is spanned over the output roller profiled according to the invention through an angle of 125° to 145°, for example, through an angle of 135°, or of about 135°. The invention further provides that at least 70%, preferably at least 80%, and particularly preferably at least 90% of the roller surface is profiled. This percentage of the surface area of the roller is therefore provided with the high spots and the low spots that alternate on the roller surface. According to one embodiment of the invention, a uniform distribution of the high spots and the low spots is provided on the roller surface. A particularly preferred embodiment of the invention is characterized in that the profile of the roller surface is embodied in the form of grooves and ridges extending circumferentially around the roller outer surface. The ridges thus form the high spots, and the grooves form the low spots. In this recommended embodiment of the invention linear contact zones are thus formed between the roller and the foraminous deposition belt. A preferred embodiment of the invention is characterized in that the position of the contact points between the foraminous deposition belt and the roller continuously changes when the foraminous deposition belt is in motion, or with rotation of the roller, as a result of the shape of the roller. The invention also provides that the position of these contact points changes discontinuously due to the profile of the roller. According to a preferred embodiment, the profile is shaped like at least one screwthread. In this case, the previously mentioned ridges (high spots) and grooves (low spots) are integral parts of a thread having a certain pitch. Due to the pitch of the thread, the contact points continuously move between the roller surface and the foraminous deposition belt in an advantageous manner. According to a recommended embodiment, two screwthreads are provided on the roller, or on the profiled roller surface. Advantageously, each thread extends from the center of the roller (with regard to the longitudinal extension of the roller) to an end of the roller. Preferably, the first thread is a right-handed thread, and the second thread is a left-handed thread. The invention also provides that the ridges and grooves do not extend angularly around the entire circumference of the roller. This way, a discontinuous embodiment of the grooves in the roller surface is also possible. According to a recommended embodiment of the invention the depth t of the low spots, or the depth t of the grooves, respectively, is 0.05 to 1.0 mm, preferably 0.05 to 0.6 mm, and most preferably 0.1 to 0.3 mm. The low spots or grooves provided on a roller may also have different depths t, or the depth t of a low spot or a groove can change along the low spot, or along the groove, in particularly, they may change continuously. A particularly preferred embodiment of the invention is characterized in that the profiled roller (macro-profile) also has a micro-profile on its surface. Preferably, the high spots of the profiled, or macro-profiled roller surfaces, also have a micro-profile on their surfaces. Advantageously, the surfaces making contact with the foraminous deposition belt of the ridges extending angularly at least partially around the circumference of the roller are micro-profiled. Preferably, the roller surface, or the surfaces of the high spots are profiled such that only point contact is made with the foraminous deposition belt. A reduction of the surface friction by up to 50% can be achieved with micro-profiling in an advantageous manner. Preferably, the micro-profiling is constituted as a globular surface topography. According to a recommended embodiment of the invention the micro-profiling of the roller surface, or of the high-spot regions is created by means of thermal spraying or galvanic coating. The invention provides that the micro-profile of the high spots have surfaces that are outwardly convex. According to a preferred embodiment the surface of the micro-high spots are shaped as tiny spheres and/or ellipsoids. With this shape of the roller, preferably of the output roller, according to the invention the disadvantages known from the previously discussed prior art can be effectively avoided. The invention is based on the knowledge that a contact-area reduction, or contact minimization between the foraminous deposition belt and the roller leads to the solution of the technical problem according to the invention. As explained above, a distinctly visible amount of the fibers is suctioned off (shot through) the foraminous deposition belt, or between the warp and weft of the foraminous deposition belt once the fibers are deposited on the foraminous deposition belt. Many known apparatuses provide an output roller that moves the foraminous deposition belt directly upstream from a calendar through an angle of about 135°. At this point, the spunbond web is transferred to the calendar, or to the calendar rollers. The shot-through filaments are pinched between the output roller surface and the foraminous deposition belt in the contact zone, and pulled opposite to the conveyor travel direction. The spunbond web in contrast is pulled by the calendar rollers and fed in the travel direction. If it is not possible to pull the shot-through and pinched filaments out of the deposition belt, the filaments tear off, and the above described fiber waste ("snow") is the result. The torn off fibers that are not removed as the "snow," and which therefore remain between the warp and weft of the deposition belt, are pressed into the foraminous deposition belt by the rollers of the machine so that they form adhesion points for the spunbond web on the foraminous deposition belt. As described above, this contamination of the foraminous deposition belt has an adverse effect on the quality of the spunbond web. The invention is now based on the knowledge that the effects described above, and the inherent disadvantages can be avoided, if the roller, preferably the output roller, is profiled according to the invention. Of significant importance is the profiling (macro-profiling) in the form of ridges and grooves extending across at least part of the circumference of the roller. A particularly preferred embodiment that has proven to be reliable in this regard is characterized in that the surfaces of the high spots (of the macro- profiling) are also micro-profiled. It should be noted that the embodiment of the roller/output roller according to the invention spunbond webs of significantly increased quality can be produced. It should also be emphasized that the measures according to the invention can be realized and relatively low expense and in a cost-effective manner. It is also not a problem to retrofit already existing systems with the rollers/output rollers according to the invention. The invention will be explained in further detail below, based on only one illustrated embodiment. Therein schematically: FIG. 1 is a schematically simplified side view of an apparatus according to the invention, FIG. 2 is a top view of a roller, or an output roller according to the invention, FIG. 3 is an enlarged section of the object of FIG. 2, and FIG. 4 is a perspective view of a micro-profiled roller surface. FIG. 1 illustrates an apparatus for the manufacture of spun non- woven material, having a foraminous deposition belt 1 on which fibers 2 made of a thermoplastic synthetic resin can be deposited to make a spunbond web 3. The fibers 2 are preferably, and in the illustrated embodiment, continuous filaments. The foraminous deposition belt 1 is spanned across a roller, or an output roller 4 through an angle of about 135°. The spunbond web 3 is transferred to a calendar 5 in a travel direction downstream of the output roller 4, or is pulled between two calendar rollers 6, 7. According to the invention the roller surface of the output roller 4 is formed with a profile (macro-profiling) that is made up of high spots and low spots. The foraminous deposition belt 1 spanned over the output roller 4 is in contact only with the high spots of the roller surface. According to a particularly preferred embodiment the profile (macro-profiling) of the roller surface is constituted by grooves 8 (low spots) and ridges 9 (high spots) that in the illustrated embodiment preferably extend angularly around the circumference of the output roller 4. This results in only line contact between the foraminous deposition belt 1 and the output roller 4. FIG. 3 shows the warp threads 10 of the foraminous deposition belt 1 above the roller surface of the output roller 4 macro-profiled with grooves 8 and ridges 9 in an enlarged section. Fibers 2 suctioned through the foraminous deposition belt 1, or shot through, can be seen below the warp threads 10. Due to the macro-profiling of the roller surface with grooves 8 and ridges 9, only some of the shot-through filaments 2 are pinched between the foraminous deposition belt 1 and the output roller 4, namely only in the area of the ridges 9. FIG. 3 also shows that the diameter of the filaments 2 is substantially smaller than the diameter of the warp threads 10 of the foraminous deposition belt 1. Preferably, and according to the illustrated embodiment, the profiling (macro-profiling) of the output roller 4 is constituted as two screwthreads 11 and 12, each extending from the center of the output roller 4 to a respective outer end of the output roller 4. Advantageously, and according to the illustrated embodiment, the screwthreads 11 and 12 are of opposite hand. In the illustrated embodiment the screwthread 11 is a left-handed screwthread, and the screwthread 12 is a right-handed screwthread. Due to the screwthread formation, or due to the pitch of the profiling the shot-through filaments 2 are clamped between the foraminous deposition belt 1 and the ridges 9 only in two regions. At this point the points contact between the foraminous deposition belt 1 and the output roller 4 continuously change with movement of the foraminous deposition belt 1, or with rotation of the output roller 4. Once the shot-through filaments 2 are no longer pinched, they can be further conveyed along with the remaining spunbond web 3 due to the tension of the calendar rollers 6 and 7. In this manner a tearing of the shot-through filaments 2, and therefore the disadvantageous "snow" can be avoided very effectively. According to a very preferred embodiment of the invention the surfaces of the high spots of the profiling (macro-profiling) are also equipped with a micro-profiling 13. In the illustrated embodiment the outer surfaces of the ridges 9 have such a micro-profiling. Advantageously, and according to the illustrated embodiment, only point contact is formed between the foraminous deposition belt 1 and the output roller 4, or the ridges 9 by means of the surface structure constituted by the micro-profiling. Preferably, and according to the illustrated embodiment, the micro-profiling corresponds to a globular surface topography. The surfaces of the microscopic spots 14 are advantageously formed as tiny spheres and/or ellipsoids. The micro-profiling of the ridge surfaces can be created, for example, by means of thermal spraying or galvanic coating. Patent Claims: 1. An apparatus for the manufacture of a spunbond web, having a foraminous deposition belt (1), on which fibers for the spunbond web (3) can be deposited, wherein the foraminous deposition belt (1) is guided over at least one roller, and the roller surface of this roller is profiled such that the foraminous deposition belt (1) is in contact with high spots of the roller surface. 2. The apparatus according to claim 1 wherein the roller is configured as an output roller (4) for the spunbond web (3). 3. The apparatus according to claim 2 wherein the output roller (4) is configured for the output of the spunbond web (3) to a calendar (5). 4. The apparatus according to one of claims 1 to 3 wherein the foraminous deposition belt (1) is spanned over the roller through an angle of at least 70°. 5. The apparatus according to one of claims 1 to 4 wherein at least 70%, preferably at least 80%, of the roller surface is profiled. 6. The apparatus according to one of claims 1 to 5 wherein the profiling of the roller surface is embodied in the form of grooves (8) and ridges (9) extending angularly around at least part of the roller circumference. 7. The apparatus according to claim 6 wherein the profiling is embodied in the form of at least one screwthread (11 and 12). 8. The apparatus according to one of claims 1 to 7 wherein the position of the contact points between the foraminous deposition belt (1) and the roller continuously and/or discontinuously changes with movement of the foraminous deposition belt (1), or with rotation of the roller due to the profiling of the roller. 9. The apparatus according to one of claims 1 to 8 wherein the high spots of the profiled roller surface also have a micro-profiling (13) on their outer surfaces. 10. The apparatus according to claim 9 wherein the micro- profiling is created by thermal spraying and/or by galvanic coating. An apparatus for the manufacture of a spunbond web, having a foraminous deposition belt, onto which the fibers for the spunbond web can be deposited. The foraminous deposition belt is spanned over at least one roller, and the roller surface of the roller is profiled such that the foraminous deposition belt is in contact only with high spots of the roller surface. |
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| Patent Number | 270618 | ||||||||
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| Indian Patent Application Number | 1011/KOL/2008 | ||||||||
| PG Journal Number | 02/2016 | ||||||||
| Publication Date | 08-Jan-2016 | ||||||||
| Grant Date | 05-Jan-2016 | ||||||||
| Date of Filing | 10-Jun-2008 | ||||||||
| Name of Patentee | REIFENHAUSER GMBH & CO. KG. MASCHINENFABRIK | ||||||||
| Applicant Address | SPICHER STRASSE 46-48 53839 TROISDORF | ||||||||
Inventors:
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| PCT International Classification Number | B32B5/02; B29C43/46 | ||||||||
| PCT International Application Number | N/A | ||||||||
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