DE10005664A1 - Melt spinning assembly has larger spinneret drillings for the outer filaments which shroud the inner filaments in the cooling station but with a constant flow throughput of the molten polymer - Google Patents

Abstract

In the melt spinning process, for synthetic filaments, the outer group of filaments from the spinneret are subjected directly to the flow of coolant while the inner group of filaments are shrouded by them. The filaments of the outer group are extruded through the spinneret drillings with a thicker cross section than the drillings for the inner filaments. The outer and inner filaments are spun through the spinneret with the same molten flow throughput, using drillings of different lengths to give equal flows and compensate for different filament thicknesses. The outer filaments are spun through spinneret drillings at equal intervals in a row, and pref. in a ring row. The inner filaments, shrouded by the spun outer filaments, are spun through equidistant drillings in a row, and pref. a ring row, or in a number of concentric ring rows. The extrusion drillings for the outer filaments have a larger dia. than those for the inner filaments, with a constant molten material flow throughput at all the spinneret drillings. The bundled filaments are carried through a preliminary and a final cooling zone, to be exposed to a coolant flow. The coolant flow supports the filament movement, before the filaments have hardened. The coolant flow speed is equal to or faster than the filament movement speed before hardening. Before the filaments set, they are passed through a concentrator with its smallest cross section at the outlet, linked to a cooling tube with a diffuser, with an under pressure to generate the coolant flow. The extruded filaments, before setting in the preliminary cooling zone, pass through a cooling shaft where wall openings link its interior with the ambient atmosphere. Directly after extrusion, the spun filaments pass through a heated zone where they are exposed to heat. An Independent claim is included for a filament melt spinning assembly with drillings (37,38) at the spinneret of different dias. The drillings (37) for the outer filaments have a larger cross section than the drillings (38) for the inner filaments in the extruded filament bundle. Preferred Features: The extrusion drillings (37,38) have an equal flow resistance despite their different sizes, to give an equal molten flow throughput at all the drillings (37,38). The drillings (37) for the outer filaments are longer than the drillings (38) for the inner filaments. The drillings (37) for the outer filaments are equidistant in a row (39), and pref. in a ring row. The drillings (38) for the inner filaments are shrouded by the outer filament drillings (37). The inner filament drillings (38) are equidistant in a row (40), and pref. a ring row or a number of concentric ring rows. The extrusion drillings (37,38) are offset from each other in neighboring drilling rows (39,40). The filament cooling station (4) has an entry cylinder (7) under the spinneret (2), with gas-permeable walls (10). A cooling tube is below the cylinder (7), in the direction of filament travel. The cylinder (7) and/or tube are linked to an air flow generator, to give a coolant air flow in the direction of filament movement. The cooling tube has a concentrator at the entry, and a diffuser at the exit. The air flow generator is an under pressure source, linked to the diffuser. The walls (10) of the cylinder have different levels of permeability, to control the air vol. passing into the cylinder (7). A heating unit, to heat the spun filaments, is between the spinneret and the cylinder leading into the cooling stage. A further Independent claim is included for a spinneret with a drilled plate (33) for melt spinning a number of filaments (5) from a molten polymer. The drillings (37,38) are in groups with a different cross section. Preferred Features: The longer drillings (37) are around the edge of the plate.

Description

The invention relates to a method for spinning a synthetic thread according to the preamble of claim 1, a spinning device for spinning a synthetic thread according to the preamble of claim 13 and one Spinneret for extruding the thread according to the preamble of the claim 24th

When producing a synthetic multifilament thread from one The thread is made of a thermoplastic material in a spinning device Variety of filaments formed. The filaments are here by means of a Spinneret extruded from the polymer melt. For this purpose, the spinneret has a Large number of equally large nozzle bores. After exiting the spinneret the filaments are passed through a flowing cooling medium, preferably air, cooled and combined to form the thread in a winder is wound into a coil. The quality of the thread is determined by the Interaction of the filament properties determined. It is therefore known that to produce a high quality yarn each filament within one Filament bundle must undergo the same treatment. Thus comes the Cooling of the filaments is of particular importance.

DE 25 39 840 describes a method and a device in which the nozzle bores in a specific arrangement in the spinneret are formed so that each extruded filament cools evenly receives. Here, the filament bundle is attached to the outside Cooling media stream acting on the filament bundle cooled. Here, the outer filaments of the filament bundle directly through the  Coolant flows through. The ones running inside the filament bundle Filaments, on the other hand, are only indirectly flowed around by the cooling medium since they partially shielded by the external filaments. With that occurs uneven cooling and uneven hot stretching of the individual filament strands, which affects the quality of the thread.

In order to cool all filament strands as evenly as possible To reach the filament bundle, many devices and methods are known who try to do this by special guidance and generation of the coolant flow Cool the filament bundle. So is a device from US 4,943,220 known in which the cooling medium flow through adjustable side walls of a Cooling shaft is affected. From US 5,034,182 it is known that Guide the filament bundle through an overpressure atmosphere of the cooling medium. In US 4,702,871, on the other hand, proposes that the filament bundle be replaced by a Conduct negative pressure atmosphere of the cooling medium. Furthermore, are from the WO 93/19229 and EP 0 530 652 devices and methods are known which the movement of the filament bundles in a cooling shaft with air-permeable wall an air flow inside the cooling shaft generated.

A coolant flow acts in all known methods and devices from the outside onto a filament bundle, so that the edge of the filament bundle running filament strands immediately and those inside the filament bundle flowing filament strands are indirectly flowed. So that's one Uniform filament treatment from the exit from the spinneret to Combining into a thread is only possible to a limited extent.

Accordingly, it is an object of the invention, a method and an apparatus for spinning a synthetic thread of the type mentioned above to further develop all the filaments when the bundle of filaments is combined are essentially the same in their properties.  

Another object of the invention is to provide a spinneret with two-dimensional arrangement To provide nozzle bores that extrude a filament bundle, which is particularly suitable for external cooling is to extrude a high quality thread.

The solution is by a method having the features of claim 1 a spinning device with the features of claim 13 and by a Spinneret given the features of claim 24.

The invention is based on the knowledge that in the case of an external one Filament bundle acting coolant flow at the edge of the Filament bundle extending filament strands (outer filaments) more intense be cooled. In addition, the outer filaments by friction of the flowing cooling medium more heavily loaded. The invention now has the advantage that the different cooling and flow effects of the cooling medium due to different properties of the filaments when they emerge from the Spinneret is balanced. According to the outer filaments of the Filament bundle with a larger filament cross section when exiting the Nozzle bore created. This results in thicker outer filaments, which in the Cool down more slowly compared to the thinner inner filaments, however is compensated by the more intensive cooling, so that at the end of the cooling section all filaments of the filament bundle have uniform cooling.

So that the individual filaments unite when combined into a thread Having a uniform titer is the development of the invention particularly advantageous in which the melt throughput per nozzle bore for all nozzle bores are the same. To this end, it is proposed that in cross section larger nozzle holes with a higher flow resistance, so that despite the larger nozzle holes, the thicker filaments with a emerge at a reduced exit speed. The diminished Exit speed causes that at a given  Pull-off speed of the thread the outer filaments of the filament bundle get a larger delay, so that a greater reduction in Filament cross section is achieved with the outer filaments. The foreign and Inner filaments of the filament bundle point to the thread when they are combined thus a substantially the same filament cross section.

The flow resistance of the nozzle bores can be easily by Change the length of the nozzle bore with the cross-section unchanged. So that leaves at a constant pressure drop between the melt pressure in the The spinneret and the melt pressure outside the spinneret are advantageous Spray speed or the exit speed of the filaments influence.

The method according to the invention and the device according to the invention are can be used regardless of the generation of the cooling medium flow. Is essential thereby that the outer filaments of the filament bundle directly, that is without any shield from which cooling medium flows. So is with Use of an annular spinneret and a cooling device, which generates a flow of cooling media radially from the inside out, the location of the External filaments defined by the filament strands running inside.

When using a cooling device which a cooling medium flow in generated essentially across the filament bundle, is the location of the External filaments through the filament strands opposite a blowing wall Are defined. The inner filaments are all filament strands that are only one shielded coolant flow.

The method according to the invention and the However, the spinning device according to the invention when using an outside internal coolant flow. Here, the Outer filaments preferably from an annular row of holes  Nozzle holes created. This training is especially for one Suitable coolant flow, the radially from the outside to the inside Filament bundle acts evenly on the circumference. The Inner filaments covered by the outer filaments. To be even To achieve distribution of the filament strands within the filament bundle, the inner filaments are generated from a large number of nozzle bores, which nozzle holes with the same distance to each other in several nested parallel rows of holes are arranged.

Around a thread with the highest possible number of individual filaments generate, the development of the invention is particularly advantageous in which the inner filaments in at least two groups with different Filament cross sections are divided. Here are the Outer filaments generated adjacent inner filaments from nozzle bores have a larger cross section than the nozzle bores inside the Filament bundle. The melt throughput of the nozzle bores kept constant so that the exit speed is based on the Center of the filament bundle gradually towards the edge of the filament bundle Row of holes slowed down to row of holes.

For threads with higher strength or with higher take-off speeds To be able to manufacture is proposed in a development of the invention, the filament bundle for cooling with the cooling medium through a Pre-cooling zone and a cooling zone, being in the cooling zone before Solidification of the filaments supports the filament movement Coolant flow is generated. For this purpose, the cooling device has one below the spinneret has arranged inlet cylinders with gas-permeable walls, which is passed through by the filament bundle. Below is the intake cylinder arranged in the thread running direction, a cooling tube, which is also from the Filament bundle is passed through. To create a filament movement  supporting cooling medium flow is the inlet cylinder or the cooling pipe connected to an air flow generator.

Depending on the type of yarn, a coolant flow with a Generate flow rate that is substantially equal to the Filament running speed before solidification. So that is achieved that the solidification point of the filaments moves away from the spinneret. This leads to delayed crystallization, which is beneficial to the physical Properties of the thread.

However, a method variant is also possible in which a Cooling media flow is generated, the flow rate of which is greater than that Filament running speed before solidification. So that can for example, highly oriented threads with high strength and even higher ones Process speed can be produced.

In a particularly advantageous method variant, the Cooling media flow the filament bundle before solidification through a confuser and a cooling tube with diffuser. This can be targeted at one point or a short distance of the spinning line of the cooling medium stream are generated.

The narrow cross section of the confuser in the spinning line is preferably such placed that it is just before the solidification point of the filaments. Through this Measure can be, for example, a tension-induced pre-orientation avoid within the filaments, which is particularly important when producing a highly oriented thread is an advantage. The thread is solidified within a very short distance, resulting in a particularly high orientation of molecular chains in the polymer. To generate the cooling medium flow the diffuser or the cooling pipe is connected to a vacuum source. The different filament cross sections of the outer filaments and the Inner filaments can particularly advantageously lead to a equal treatment of all filaments in the cooling tube occurs.  

To influence the cooling medium flow acting on the filament bundle the gas permeable wall of the inlet cylinder is advantageous in Thread running direction in several zones, each with different Divided gas permeability. This makes it possible to target the Properties of the outer and inner filaments of the filament bundle influence to take. The influence can be on the one hand that all filaments if possible, pre-cooling for solidification under the same cooling conditions the edge zone. Furthermore, the filaments can be run into the Cooling tube and the formation of the supporting filament movement Coolant flow through the in particular in the lower area of the Influence the amount of air entering the intake cylinder. The through the wall of the The amount of air entering the intake cylinder is proportionally dependent on the Gas permeability or the porosity of the wall.

Such a measure can be done by the method variant, in which the The filament bundle is passed through a heating zone immediately after the extrusion, in which a quantity of heat is supplied to the filaments, even further improve. The spinning device according to the invention has one for this purpose heater arranged below the spinneret. The heater can be done by a radiant heater or by a heated air flow, which is generated in the direction of the filament bundle.

The method according to the invention and the spinning device according to the invention are based on a spinneret, which is a nozzle plate with a variety of Has nozzle bores with unequal sized, freely flowable Cross sections are formed. Here, the nozzle bores in Edge area of the nozzle plate has a larger cross section than the rest Nozzle bores.

The known spinnerets for extruding a bundle of filaments, such as described for example in DE 196 28 646, are characterized by a  Nozzle plate with equally large nozzle bores. Such spinnerets however, require a cooling device that is the same on each filament acting coolant flow generated.

The spinneret according to the invention, on the other hand, is distinguished by the fact that in particular a flow of cooling media acting from the inside out on a filament bundle a thread with uniform filament properties is generated.

In order to achieve an even melt throughput per nozzle bore, are the nozzle bores in the nozzle plate of the spinnerets in their lengths trained differently. Here, the nozzle bores are larger Flow cross-section on a greater length.

Further advantageous developments of the invention are in the subclaims Are defined.

The method according to the invention is illustrated by means of some exemplary embodiments of the Devices according to the invention with reference to the accompanying Drawings described in more detail.

They represent:

Fig. 1 shows schematically a first embodiment of a spinning device according to the invention;

FIG. 2 shows schematically an inventive spinneret of the spinning device from FIG. 1;

Fig. 3 shows schematically a further embodiment of a spinneret according to the invention;

Fig. 4 schematically shows another embodiment of a spinning device according to the invention;

Fig. 5 shows schematically an embodiment of a cooling device.

In Fig. 1 a first embodiment of a spinning device according to the invention is shown for spinning a synthetic multifilament yarn. Here, a thread 12 is spun from a thermoplastic material. The thermoplastic material is melted by means of an extruder or a pump (not shown here). The polymer melt is conveyed via a melt line 3 by means of a spinning pump to a heated spinning head 1 . A spinneret 2 is attached to the underside of the spinning head 1 . The spinneret 2 has a plurality of nozzle bores on the underside in a nozzle plate, the arrangement and design of which is shown in FIG. 2, which will be described later. The melt emerges from the nozzle bores of the spinneret 2 in the form of fine filament strands 5 . The filaments 5 form a filament bundle 6 . Here, the filaments that run at the edge of the filament bundle are extruded from nozzle bores with a larger cross section, so that the filament bundle consists of two groups of filaments. The filaments running at the edge of the filament bundle 6 are referred to as outer filaments and the filaments running inside the filament bundle as inner filaments. The inner filaments are covered by the outer filaments. The outer filaments have a larger filament cross section than the inner filaments.

The filament bundle 6 is guided below the spinneret 2 by a cooling device 4 . The cooling device 4 consists of an inlet cylinder 7 , which has a gas-permeable wall 10 . The filament bundle 6 passes through the inlet cylinder 7 so that the wall 10 envelops the filament bundle 6 . The inlet cylinder 7 is arranged in a blow box 8 . The blow box 8 has an inlet 9 through which a cooling medium is introduced into the blow box 8 . For this purpose, the inlet 9 is connected to an air flow generator (not shown here). The cooling medium exits through the wall 10 of the inlet cylinder 7 and flows essentially transversely from the outside into the filament bundle 6 . The filament bundle 6 emerges from an outlet opening 13 formed on the underside of the cooling device 4 and is brought together into a thread 12 at a point of convergence. The point of convergence can be formed by a preparation device or - as shown - by a thread guide 11 . After passing through a treatment device 17 , the thread 12 is wound into a bobbin 23 in a winding device 20 . The coil 23 is generated on a driven winding spindle 24 . A pressure roller 22 arranged in the thread run bears against the circumference of the bobbin 23 . The pressure roller 22 serves to regulate the peripheral speed of the coil 23 .

In the spinning device shown in FIG. 1, a polymer melt is conveyed to the spinning head 1 and extruded into a multiplicity of filaments 5 via the spinneret 2 . The filament bundle 6 is drawn off the winding device 20 . Here, the filament bundle 6 passes through a cooling zone within the inlet cylinder 7 of the cooling device 4 with increasing speed. The filament bundle 6 emerges on the underside of the cooling device 4 through an outlet opening 13 and is brought together to form the thread 12 .

Depending on the manufacturing process, a swirling nozzle 18 can be arranged in the treatment device 17 , through which the thread is passed to increase the thread closure.

However, the treatment device 17 can also have one or more unheated or heated godets, so that the thread is drawn before winding. It is also possible to arrange additional heating devices for stretching or relaxation within the treatment device 17 .

To cool the filaments after extrusion, the filament bundle 6 is passed through the cooling device 4 . Here, a flow of cooling media is directed onto the filament bundle from the outside. Due to the flat arrangement of the nozzle bores, the outer filaments of the filament bundle 6 are cooled more strongly than the inner filaments running inside. However, due to the larger filament cross section of the outer filaments, there is no premature solidification of the outer filaments. The solidification and thus the crystallization of the filaments of the filament bundle 6 will occur simultaneously for the outer filaments and the inner elements. Thus, when the filament bundle 6 is combined, all the filaments have the same properties. In order for the filaments of the thread to have an essentially uniform filament cross section when they are combined, the outer filaments of the filament bundle are extruded from the spinneret at a lower exit speed. Due to the take-off speed predetermined by the winding device 20, the outer filaments are stretched higher in comparison to the inner filaments of the filament bundle 6 . The greater distortion of the outer filaments leads to a higher tapering of the filament strands. Each individual filament strand of the filament bundle 6 is produced with the same melt throughput per nozzle bore of the spinneret 2 .

FIG. 2 shows the spinneret used in the spinning device from FIG. 1. Fig. 2.1 shows a bottom view of the spinneret 2 , and Fig. 2.2 shows schematically a partial cross section of the spinneret.

The following description applies equally to the thus Fig. 2.1 and Fig. 2.2. The spinneret 2 has a cylindrical nozzle pot 32 which is closed on the underside by a circular nozzle plate 33 . The opposite end of the nozzle pot 32 is connected to a melt line (not shown here). The spinneret 2 has a filter element 35 in the interior of the nozzle pot 32 . The filter element 35 is supported on a support plate 34 . The support plate 34 abuts on the nozzle plate 33, wherein an outlet chamber 36 is formed between the support plate 34 and the nozzle plate 33rd The support plate 34 has several penetrations on the entire surface.

Numerous nozzle bores 37 are made in a row 39 of holes in the edge region of the nozzle plate 33 . The nozzle bores 37 have a free cross-section with the diameter D _A. They penetrate the nozzle plate 33 with a length of L _A. The nozzle bores 37 each have the same distance from one another in the row of bores 39 .

A plurality of nozzle bores 38 are made in the nozzle plate 33 within the row of holes 39 . The nozzle bores 38 have a freely flowable cross section with the diameter D _I. The diameter D _{I of} the nozzle bores 38 is smaller than the diameter D _{A of} the outer nozzle bores 37 . The nozzle bores 38 penetrate the nozzle plate 33 with a constant cross section in a length L _I. Here, the ratio of the length of the nozzle bore to the diameter of the nozzle bore is chosen such that when the melt pressure is present within the nozzle pot 32, each of the nozzle bores 37 and 38 produces a filament strand with the same melt throughput. The filament strands are thus extruded at different exit speeds from the nozzle bores 37 and 38 of the nozzle plate 33 . The outer filaments of the filament bundle, which emerge from the larger nozzle bores 37 , have a lower exit speed than the inner filaments emerging from the nozzle bores 38 .

In order to extrude the polymer melt, a melt flow is fed to the spinneret 2 under high pressure. The melt penetrates the filter element 35 and passes through the openings of the support plate 34 into the outlet chamber 36 . Due to the pressure load, the melt is now divided into a large number of partial flows per nozzle bore, so that a large number of filament strands are formed on the outlet side of the spinneret 2 . The filaments (outer filaments) emerging from the nozzle bores 37 at the edge of the spinneret have the largest filament cross section.

According to the invention is achieved in that after passing through the cooling zone and after stretching within the cooling zone, the filaments are combined in their properties are essentially the same, making a high quality Thread is made.

In Fig. 3, another embodiment is shown of a spinneret according to the invention. 3.2 Fig. 3.1 shows a bottom view of the spinning nozzle, and Fig. Is a partial cross-section of the spinneret. The spinneret can also be used in the device according to FIG. 1. The structure is essentially identical to the spinneret described in FIG. 2. In this respect, reference is made to the preceding description.

In the spinneret shown in FIG. 3, the nozzle plate 33 is designed with a total of three groups of nozzle bores with different bore cross sections. The first group is formed by the nozzle bores 37 , which are arranged in a row of bores 39 in the edge region of the circular nozzle plate 33 . Adjacent to the nozzle bores 37 , a second group of nozzle bores 38 is made in the nozzle plate, which are also made in rows 40 of bores with different diameters. A third group of nozzle bores 41 is introduced within the rows 40 of bores. The nozzle bore 41 has a free cross section with the diameter D _I2 . The nozzle bore 41 penetrates the nozzle plate with the freely flowable cross section D _I2 with a length L _I2 . In contrast, the second group of nozzle bores 38 has a somewhat larger bore cross section with the diameter D _I1 and the bore length L _I1 , which is greater than the length L _I2 . In contrast, the nozzle bores 37 made at the edge of the nozzle plate 33 have the largest bore cross section with the diameter D _A with the greatest length L _A. The flow resistance is influenced by the different lengths of the nozzle bores 37 , 38 and 41 . The ratio between the diameter of the nozzle bore and the length of the nozzle bore L: D is chosen such that the mass flow per unit of time is the same for each nozzle bore regardless of its outlet cross section. As a result, thicker filaments will emerge from the spinneret more slowly.

Due to the coordination between the filament cross section and the exit speed can be taken into account the used Cooling device a high uniform formation of the filaments shortly before Reaching together into a thread.

In FIG. 4, a further embodiment of a spinning device according to the invention is shown for spinning a synthetic yarn. Compared to the embodiment shown in FIG. 1, the cooling device 4 of the spinning device shown in FIG. 4 is constructed in such a way that a cooling medium flow which supports the movement of the filaments is generated. This design results in delayed cooling and thus delayed solidification of the individual filaments. This leads to delayed crystallization, which has a favorable effect on the desired physical properties of the thread. It is particularly advantageous here that the filaments have two different filament cross-sections and different exit speeds when they emerge from the spinneret.

The spinning head 1 and the spinneret 2 are also identical to the previously described embodiment of the spinning device. In this respect, reference is made to the preceding description.

The cooling device 4 consists of an inlet cylinder 7 arranged below the spinneret. The inlet cylinder 7 has a gas-permeable wall 10 . Below the inlet cylinder 7 , a cooling pipe 44 connects in the thread running direction. The cooling tube 44 is connected to the inlet cylinder 7 via a confuser 43 . At the opposite end of the cooling tube 44 , a diffuser 45 is connected to the cooling tube 44 , which opens into an outlet chamber 46 . On the underside of the outlet chamber 46 , an outlet opening 13 is made in the outlet chamber 11 in the thread running plane. A suction port 14 opens on one side of the outlet chamber 11 . Via the suction nozzle 14 a arranged at the free end 14 of the suction air stream generator 15 is connected via the outlet chamber 11 to the diffuser 45 and the cooling tube 44th The air flow generator 15 is designed as a vacuum source. The vacuum source can be formed, for example, by a vacuum pump or a blower, which generates a vacuum in the cooling tube 44 .

In the outlet chamber 46 , a screen cylinder 30 is attached in the extension of the diffuser 45 . The screen cylinder 30 has an air-permeable wall and penetrates the outlet chamber 46 to the underside. A preparation device 16 and a winding device 20 are arranged in the thread running plane below the vacuum chamber 11 . The winding device 20 consists of a head thread guide 19 , the head thread guide 19 indicates the beginning of the traversing triangle, which is created by the back and forth movement of a traversing thread guide of a traversing device 21 . A pressure roller 22 is arranged below the traversing device 21 . The pressure roller 22 lies against the circumference of a coil 23 to be wound. The bobbin 23 is generated on a rotating bobbin 24 . For this purpose, the winding spindle 24 is driven by the spindle motor 25 . The drive of the winding spindle 25 is regulated depending on the speed of the pressure roller 22 in such a way that the peripheral speed of the bobbin and thus the winding speed remains substantially constant during winding.

Between the preparation device 16 and the winding device 20 , the treatment device 17 is arranged in the thread path, which in this case is formed by a swirling nozzle 18 . Inside the intermingling nozzle 18 , the multifilament thread is swirled by an air stream, so that the individual filaments lead to a thread closure due to intertwining.

In this embodiment of the spinning device, the filament bundle 6 passes through the cooling zone within the inlet cylinder 7 with increasing speed. The filament bundle 6 is then drawn into the confuser 43 . The confuser 43 is connected to the vacuum source 15 via the cooling tube 44 and the diffuser 10 . Thus, due to the negative pressure effect, the ambient air present on the outside of the inlet cylinder 7 is sucked into the cooling shaft. The air flowing in as the cooling medium leads to a pre-cooling of the filaments, so that the outer layers of the filaments solidify. Due to the narrowest cross section in the confuser 43 , the air flow is accelerated under the action of the vacuum source 15 in such a way that the air flow counteracting the filament movement is reduced or avoided. This supports the movement of the filament so that air friction on the as yet unconsolidated filament is avoided. The aim here is to accelerate the flow rate as far as possible in the area of the filament rate. In the further course in the cooling tube 44 , the filaments are further cooled. With such an arrangement, the effect of the air flow generated can be influenced by larger filament cross sections of the outer filaments and lower exit speeds of the outer filaments from the spinneret such that all filaments of the filament bundle have essentially the same properties when they leave the cooling device.

In order to generate as little turbulence as possible and thus a flow profile that is as constant as possible in the outlet region of the diffuser 45 , the air flow is introduced via the diffuser 45 into the screen cylinder 30 , which is arranged within the outlet chamber 46 and is connected to the vacuum source 15 . The cooling air is then sucked out of the outlet chamber 11 via the nozzle 14 and discharged. The filament bundle emerges from the outlet opening 13 and is brought together into a thread in the preparation device.

FIG. 5 shows an exemplary embodiment of an inlet cylinder as it could be used, for example, in the spinning device according to FIG. 1 or according to FIG. 4. The inlet cylinder 7 has a wall 10 which is designed as a perforated plate with two different perforations 29 and 26 . In an upper zone at the end of the inlet cylinder, which faces the spinneret 2 , a small diameter hole 29 is made . The perforation leads to a schematically indicated inflow profile 28 in the upper zone. The inflow profile 28 , which is symbolized by arrows, gives a measure of the amount of air entering the cooling shaft. The perforation 29 is the same within the upper zone. The amount of air thus increases with increasing distance from the spinneret due to the negative pressure effect in the confuser 43 and due to the increasing filament speed of the filament bundle.

In a lower zone, which is formed at the end facing the confuser 43 , the wall 10 has a perforation 26 with a larger opening cross section. As represented by the symbolized inflow profile 27 , a larger amount of air will enter the spinning shaft in the lower zone. Here, too, the tendency can be seen that the inflowing air quantity increases with increasing distance from the spinneret.

The inflow profile shown in FIG. 5 above the wall of the cooling cylinder is particularly suitable in order to obtain slow and low pre-cooling of the filaments. In particular, this leads to a further improvement in the uniform treatment of the filaments. Here, the pre-cooling and the formation of the cooling medium flow can advantageously be influenced.

In the embodiment of the spinning device shown in FIG. 5, a heating device 31 is arranged between the inlet cylinder 7 and the spinning head 1 . The heating device 31 leads to a thermal treatment of the filaments, so that further slowed cooling occurs. In this arrangement shown in FIG. 5, the heating device can be combined with its previously described embodiment of the spinning device.

The devices described above are all suitable, the invention Procedure. Threads made of polyester, polyamide or Advantageously manufacture polypropylene. Depending on the choice of treatment facility and take-off speed can be partially drawn threads (POY) or fully drawn threads (FDY) are produced. In particular, the process and the device is suitable to make highly oriented yarns (HOY) with higher To generate strengths.

In the spinning device according to the invention, the formation of the spinneret exemplary. The flat arrangement of the nozzle bores can be in Depending on the cooling device used in each case also in rectangular Form shape, oval or ring-shaped. It is essential, however, that the filaments of a filament bundle directly flowed around a cooling medium have a largest filament cross-section. To further support the The procedure further recommends the exit speed of the thicker Slow down filaments so that a higher warp at given Pull-off speed of the filament bundle occurs.  

Reference list

1

Spinning head

2nd

Spinneret

3rd

Melting line

4th

Cooling device

5

Filaments

6

Filament bundle

7

Inlet cylinder

8th

Blow box

9

Intake

10th

Wall

11

Thread guide

12th

thread

13

Outlet opening

14

Suction port

15

Air flow generator, suction device

16

Preparation device

17th

Treatment facility

18th

Swirl nozzle

19th

Head thread guide

20th

Winding device

21

Traversing device

22

Pressure roller

23

Kitchen sink

24th

Winding spindle

25th

Spindle drive

26

Perforation

27

Flow profile

28

Flow profile

29

Perforation

30th

Screen cylinder

31

Heating device

32

Nozzle pot

33

Nozzle plate

34

Support plate

35

Filter element

36

Outlet chamber

37

Nozzle bore

38

Nozzle bore

39

Row of holes

40

Row of holes

41

Nozzle bore

42

Row of holes

43

Confuser

44

Cooling pipe

45

Diffuser

46

Outlet chamber

Claims (28)

1. A method for spinning a synthetic thread which is formed by combining a bundle of filaments consisting of a plurality of individual filaments and which is wound up into a bobbin by means of a winding device connected downstream of the spinning device, in which the filaments are extruded by means of a spinneret having a plurality of nozzle bores and in which the filament bundle is cooled by a gaseous cooling medium, a first group of filaments (outer filaments) of the filament bundle being directly surrounded by the cooling medium and a second group of filaments (inner filaments) of the filament bundle being indirectly shielded from the cooling medium by the outer filaments is characterized in that the outer filaments have a larger filament cross-section than the inner filaments when they emerge from the nozzle bores. 2. The method according to claim 1, characterized in that the Outer filaments and the inner filaments of the filament bundle each with same melt throughput can be generated per nozzle bore. 3. The method according to claim 2, characterized in that the Melt throughput of the nozzle bores through different lengths of the Nozzle holes is evened out. 4. The method according to any one of claims 1 to 3, characterized in that the outer filaments generated from a variety of nozzle holes which nozzle bores are the same distance apart in one Row of holes, preferably in an annular row of holes are arranged.   5. The method according to claim 4, characterized in that the Inner filaments are encased by the outer filaments and that the Inner filaments are generated from a large number of nozzle bores, which nozzle bores are the same distance apart in one Row of holes, preferably in an annular row of holes or in several nested concentric rows of holes are arranged. 6. The method according to claim 5, characterized in that with the Generated nozzle holes of the outer rows of holes Inner filaments have a larger filament cross section than those with generated the nozzle holes of the inner row of holes Inner filaments, the melt flow rate of the nozzle holes of the Row of holes is the same. 7. The method according to any one of the preceding claims, characterized characterized in that the filament bundle for cooling with the Coolant passed through a pre-cooling zone and a cooling zone is, the in the cooling zone before the solidification of the filaments Filament movement supporting coolant flow is generated. 8. The method according to claim 7, characterized in that the Coolant flow has a flow rate that in essentially equal to the running speed of the filaments before Freeze is. 9. The method according to claim 7, characterized in that the Coolant flow has a flow rate that is greater than Filament running speed before solidification. 10. The method according to any one of claims 7 to 9, characterized in that  the filaments are passed through a confuser before solidification, the confuser having its narrowest cross section on the outlet side and is connected to a cooling tube with a diffuser, to which for Generation of the coolant flow is under vacuum. 11. The method according to any one of claims 7 to 10, characterized in that the filament bundle after extrusion and before solidification in the Pre-cooling zone is passed through a cooling shaft that through a air-permeable cylindrical wall connected to the ambient air is. 12. The method according to any one of the preceding claims, characterized characterized in that the filament bundle immediately after extrusion be passed through a heating zone in which the filaments Amount of heat is supplied. 13. Spinning device for spinning a synthetic thread ( 12 ) which is formed by combining a bundle of filaments ( 6 ) consisting of a plurality of individual filaments ( 5 ) and which is wound up into a bobbin ( 23 ) by means of a winding device ( 20 ) connected downstream of the spinning device with a spinneret ( 2 ), which has a plurality of nozzle bores ( 37 , 38 ) on the underside for extruding the filaments ( 5 ), and with a cooling device ( 4 ), which acts on the filament bundle ( 6 ) gaseous cooling medium flow generated, wherein a first group of filaments (outer filaments) of the filament bundle ( 6 ) flows directly around the cooling medium and a second group of filaments (inner filaments) of the filament bundle ( 6 ) flows indirectly shielded from the cooling medium by the outer filaments, characterized in that that the nozzle bores ( 37 , 38 ) of the spinneret for generating the Filaments are formed with unequal cross-sections through which the air can flow, the nozzle bores ( 37 ) of the outer filaments having a larger cross section than the nozzle bores ( 38 ) of the inner filaments. 14. Spinning device according to claim 13, characterized in that the nozzle bores ( 37 ) of the outer filaments in comparison to the nozzle bores ( 38 ) of the inner filaments are designed in spite of different bore cross-sections with an equally large flow resistance that a substantially equal melt flow rate per nozzle bore all nozzle bores ( 37 , 38 ) is reached. 15. Spinning device according to claim 14, characterized in that the nozzle bores ( 37 ) of the outer filaments have a greater length in comparison to the nozzle bores ( 38 ) of the inner filaments. 16. Spinning device according to one of claims 13 to 15, characterized in that the nozzle bores ( 37 ) of the outer filaments on the spinneret ( 2 ) are arranged at the same distance from one another on a row of bores ( 39 ), preferably an annular row of bores. 17. Spinning device according to one of claims 13 to 16, characterized in that the nozzle bores ( 38 ) of the inner filaments on the spinneret ( 2 ) are encased by the nozzle bores ( 37 ) of the outer filaments and that the nozzle bores ( 38 ) of the inner filaments are at the same distance are arranged in a row of holes ( 40 ), preferably in an annular row of holes or in a plurality of nested concentric rows of holes. 18. Spinning device according to claim 17, characterized in that the nozzle bores ( 38 ) of the outer row of bores ( 40 ) of the inner filaments have a larger cross section than the nozzle bores ( 41 ) of the inner row of bores ( 42 ), the melt throughput of the nozzle bores ( 38 , 41 ) the rows of holes ( 40 , 42 ) is the same. 19. Spinning device according to claim 17 or 18, characterized in that the nozzle bores ( 37 , 38 ) of adjacent rows of bores ( 39 , 40 ) in the direction transverse to the spinneret ( 2 ) are arranged offset to one another. 20. Spinning device according to one of claims 13 to 19, characterized in that the cooling device ( 4 ) has an inlet cylinder ( 7 ) arranged below the spinneret ( 2 ) with gas-permeable walls ( 10 ) and a cooling tube arranged in the thread running direction below the inlet cylinder ( 7 ) ( 44 ) and that the inlet cylinder ( 7 ) or the cooling tube ( 44 ) is connected to an air flow generator ( 15 ) in such a way that a cooling medium flow flowing in the thread running direction is formed. 21. Spinning device according to claim 20, characterized in that the cooling tube ( 44 ) has a confuser ( 43 ) on the inlet side and a diffuser ( 45 ) on the outlet side, and in that the air flow generator ( 15 ) is a vacuum source which is connected to the diffuser ( 45 ) is connected. 22. Spinning device according to claim 20 or 21, characterized in that the inlet cylinder ( 7 ) in the thread running direction is divided into several zones, each with different gas permeability of the wall ( 10 ) for controlling the amount of air entering the inlet cylinder ( 7 ). 23. Spinning device according to one of claims 13 to 22, characterized in that a heating device ( 31 ) for the thermal treatment of the filaments is arranged between the spinneret and the inlet cylinder. 24. Spinneret for extruding a plurality of filaments ( 5 ) from a polymer melt with a nozzle plate ( 33 ) which has a plurality of nozzle bores ( 37 , 38 ) for the outlet of the polymer melt, the nozzle bores ( 37 , 38 ) being arranged in one surface are characterized in that the nozzle bores ( 37 , 38 ) are formed with unequal cross-sections of free flow, the nozzle bores ( 37 ) having the largest cross-section at the edge of the surface. 25. Spinneret according to claim 24, characterized in that the nozzle bores ( 37 , 38 ) with unequal lengths each have constant cross sections over the length, the nozzle bores ( 37 ) having the greatest length at the edge of the surface. 26. Spinneret according to claim 25, characterized in that the nozzle bores ( 37 , 38 ) are designed in their lengths and their cross sections such that a substantially equal melt flow rate per nozzle bore can be achieved in all nozzle bores ( 37 , 38 ). 27. Spinning nozzle according to one of claims 24 to 26, characterized in that the nozzle bores ( 37 , 38 ) are arranged at the same distance from one another on a plurality of parallel rows of bores ( 39 , 40 ), preferably annular nested rows of bores. 28. Spinneret according to claim 27, characterized in that the nozzle bores ( 37 , 38 ) of adjacent rows of bores ( 39 , 40 ) are arranged offset to one another in the direction transverse to the spinneret.