EP1093535A1

EP1093535A1 - Filtering device and spinning head

Info

Publication number: EP1093535A1
Application number: EP99927841A
Authority: EP
Inventors: Ralf Wnuk; Norbert Lang; Jürgen HAUSDORF; Markus Reichwein; Roland Nitschke; Jörg ALEXANDER; Stefan Becker
Original assignee: Barmag AG; Hydac Process Technology GmbH; Barmag Barmer Maschinenfabrik AG
Current assignee: Hydac Process Technology GmbH; Oerlikon Barmag AG
Priority date: 1998-06-08
Filing date: 1999-06-02
Publication date: 2001-04-25
Anticipated expiration: 2019-06-02
Also published as: DE59902419D1; KR20010043756A; US6604928B1; CN1304462A; CN1105792C; JP4343436B2; WO1999064648A1; ES2182537T3; EP1093535B1; KR100516318B1; JP2002517629A; DE19825532A1

Abstract

The invention relates to a filtering device for a spinning head (10) for producing plastic threads and to the spinning head itself (10). The spinning head has a housing (12) in which the plastic melt flows through a filter element (18) under pressure before exiting the spinnerets. Said filter element is provided with a filtering material (20) that is subjected to an axial contact pressure through a distributor device (22), according to the degree of pressure of the melt. This contact pressure acts upon the sealing edges (26, 28) of the filter element (18), the sealing gaps (24) being closed. The special geometrical configuration of the filter element (18) and/or its elasticity guarantee advantageous filtering in terms of energy. The filtering system is resistant to pressure and provides good, permanent sealing.

Description

Filter device and spinning head

The invention relates to a filter device for a spinning head and a spinning head for the production of plastic threads, which has a housing in which the plastic melt flows through a filter element with a filter material under pressure before it emerges from the spinning nozzles Melt pressure experiences an axial contact force, which acts on the sealing edges of the filter element by closing sealing gaps.

In so-called melt spinning, the polymer melt must be subjected to very fine filtration using a sand filter, metal powder filter or filter candles immediately before it passes through the nozzle plate. From EP 0 658 638 B1 it is known to pass the polymer melt through a plurality of filter candles made of metal mesh arranged in parallel with the disadvantage that a uniform flow against all filter candles is practically impossible, with the result that individual filter candles preferentially get dirty and all filter candles must be cleaned or replaced after a short period of time. In a generic spinning head according to DE 42 25 341 A1, a single ring filter element has already been proposed, which comprises a mixing device in the interior of the housing, which serves to bring the filtered melt stream coming out of the filter with homogeneous mixing; only the known filter element is only slightly stable in terms of pressure and the elasticity of the clamped filter element is not sufficient to completely seal off the possible passage points in the form of the sealing gaps via its sealing edges. In order to counter this disadvantage, in practice one has already started to replace the ring filter element with plate filter packets; The resulting deflection of the melt flow within the filter element with its disk filter disks alone results in an unfavorable energetic flow behavior, which hinders the actual filtering process for the plastic melt. The solution in question is also expensive to implement.

Furthermore, a spinning head is known from DE 42 27 1 14, in which the stability of the ring filter element is increased due to radial support by a distributor device, but with the result that the filter element can be flowed through very unevenly.

From US Pat. Nos. 4,661, 249 and 2,881, 474, filter elements with a support tube are known which have wall-side fluid passages which are enclosed by a filter material. The end of the filter element is firmly clamped in housing parts of the filter device, so that only a seal in the area of predeterminable seal values can be achieved there. If there are signs of settlement in the seals due to the static clamping, this is associated with a loss of tightness.

Based on this prior art, the object of the invention is to create an improved filter device for a spinning head. fen, which allows a low-energy filtration operation, is pressure-stable, ensures a good permanent seal and is inexpensive to implement. A corresponding object is achieved by a filter device with the features of claims 1 and 2.

Another object of the invention is to develop a spinning head of the type mentioned at the outset in such a way that there is a particularly homogeneous plastic melt for producing a multifilament synthetic thread at the outlet. A spinning head with the features according to claim 12 solves this problem.

Characterized in that, according to the characterizing part of claim 1, the filter element has a support tube with wall-side fluid passages to form an exchangeable structural unit, which is surrounded by the filter material, which at least at one end protrudes axially with its sealing edge over the support tube and / or axially is set back, a pressure-stable unit is formed, which is reliable in operation even at high melt pressures. Since the flow direction for the plastic melt takes place uniformly in one direction over the entire length of the filter element, the flow is energetically favorable and the flow of melt is not opposed by any artificial resistance. Due to the protruding or recessed end of the filter material, which forms the respective sealing edge, a reliable sealing of the possible passage points in the form of the sealing gaps is ensured given the elastic behavior of the filter element. Since the filter element in question can be created from standard components, in particular from conventional metal mesh filter materials, its production is inexpensive.

The corresponding success according to the invention can also be achieved in accordance with the characterizing part of claim 2 in that a flat sealing edge is present at the filter element at least at one end, the overall rigidity of the filter element being such is chosen that the sealing gap is closed under the contact pressure. Depending on the contact pressure, a dynamic sealing system for the filter device with a spinning head is thus implemented, which seals more and more with increasing contact pressure.

The spinning head according to the invention is particularly characterized in that the plastic melt is guided uniformly from inlet to outlet without different dwell times. The delivery space formed between the melt-permeable support tube and the distributor head ensures that the filter element flows through uniformly and that the filtered plastic melt is discharged unhindered to the outlet. A high pressure stability of the filter element is achieved through the support tube.

In order to obtain a favorable flow pattern, it is particularly advantageous to expand the cross-section of the delivery space through which the flow flows, through a conical taper of the distributor head towards the outlet.

To improve the lateral inflow of the plastic melt into the filter element, an underside of the pressure plate can be chamfered on the displacement device between the pressure plate and the distributor head, which underside acts as a sealing surface against a sealing edge of the filter element. This avoids disadvantageous flow-related backlogs.

For this purpose, the underside of the pressure plate is preferably inclined at an angle of 0 ° to 40 ° in the direction of the exit of the plastic melt in the spinning head.

So that the melt at the ends of the filter element, in particular at the end of the filter element facing the pressure plate, can flow safely into the filter material without significant hindrance, the support tube ^¬ and the filter material are connected to form a cylindrical filter jacket the ends of which are formed by the sealing surfaces of the filter element. It is particularly advantageous that the filter material at the end of the filter element facing the pressure plate protrudes axially with its sealing edge over the support tube or is set back, so that there is no accumulation corner.

Surprisingly, the elasticity of the filter jacket is not restricted by the radial stability of the support tube. Due to the fluid passages in the support tube, the filter jacket has an axial elasticity, which dynamically supports the closing of the sealing gaps over the sealing edges of the filter element under the axial contact force. The elasticity of the filter element can be favored and increased by the fact that the filter element does not have end caps made of a correspondingly rigid material, but rather the elasticity is achieved solely by compressing the filter material and welding it at the end.

Further advantageous embodiments are the subject of the dependent claims.

The filter device for one and the spinning head are explained in more detail below with the aid of the drawing.

They show the principle and not to scale

1 shows a longitudinal section through a spinning head according to the invention with a filter device according to the invention;

2 shows a longitudinal section through the filter element with support tube and

Filter material;

2a shows a longitudinal section through a modified filter element with support tube and filter material;

3 shows a longitudinal section through the support tube according to the Fig.2. 1 shows as a whole 10 a spinning head for producing plastic threads from a plastic melt (not shown), in particular a polymer melt. The spinning head 10 has a housing 12 in the manner of a hollow cylinder with an upper inlet opening 14 for the entry of the plastic melt and with a lower outlet opening 16 for receiving a spinneret which has numerous nozzle bores for the exit of the filaments of a multifilament synthetic thread (not shown). For the production of the plastic filaments, the lower outlet opening 16 is closed with a spinneret plate in the usual and therefore not shown in detail. As seen in the direction of FIG. 1, the right half of the picture represents the spinning head in an initial position and the left half relates to the operating position in which the movable parts of the spinning head 10 are shown in their operating position under the pressure and force of the plastic melt.

For a filtering process of the plastic melt, it is passed under pressure through a filter element 18 with a filter material 20 before it emerges from the spinnerets via the spinneret plate, the flow direction being radial from the outside inwards. The filter element 18 in question is shown in an improved illustration in FIG. Depending on its strength of the melt pressure, the filter material 20 experiences an axial contact force via a distributor device 22, which acts upon the sealing edges 26, 28 of the filter element 18 as a possible passage point for the plastic melt by closing sealing gaps 24. The filter element 18 has a support tube 30 with fluid passages 32 for the plastic melt, forming an exchangeable structural unit, as shown in FIG. 2, although not all of them are shown in FIG. 3, which shows the support tube 30 Passage points 32 are shown. However, these are assigned to each other in groups of three evenly distributed along the outer circumference of the drum-like support tube 30.

The filter material 20 encloses the same with the support tube 30. As FIG. 2 further shows, the filter material 20, viewed in the direction of looking at the figure, protrudes axially at the upper end with its sealing edge 28 via the support tube 30 and axially back at the lower end.

The filter material 20 preferably consists of a pleated filter jacket 34 made of wire mesh or of a metal fiber fleece, in particular in the form of stainless steel. To connect the jacket ends, these are connected to one another via a longitudinal weld seam (not shown) to form a cylindrical hollow body. Instead of pleating, the filter jacket can also be wound in one or more layers around the support tube 30 (not shown). In the embodiment shown, the filter jacket 34 consists of a multilayer stainless steel mesh with a filter fineness between 5 μm to 500 μm, in particular 50 / vm to 1 50 μm. The filter material is also commercially available under the brand name "Micron". If, as in the present case, the filter jacket 34 is pleated, there is an independent sealing edge 26, 28 for each filter fold on the opposite end sides of the filter jacket 34 The pleated design of the filter jacket 34 can also consist of a continuous cylindrical filter jacket with a flat outer circumference Furthermore, the respective filter material 20 can form the filter jacket 34 in one piece or in one piece, the support tube 30 being an integral part of the entire filter element Embodiment, the support tube 30 is also completely eliminated and formed exclusively by the filter element cylinder.

The filter jacket 34 has a predeterminable elasticity which, under the aforementioned axial contact force during the filtering process, ie during the operation of the spinning head 10, closes the respective sealing gap. 24 supported via the sealing edges 26, 28 of the filter element 18. As further shown in FIG. 2, the sealing edges 26, 28 of the filter element 18 are inclined relative to the circular planes 36 of the support tube 30 by a predeterminable angular amount, in particular by 15 °, in the direction of the entry of the plastic melt into the spinning head 10. This results in two radial sealing flanges 38 parallel to the circular planes 36 which, as in the illustration according to FIG. 2, are correspondingly compressed in a filter jacket 34 and are thus disc-shaped. A corresponding compression occurs even if the filter jacket is, as already mentioned, hollow-cylindrical. On the outer circumference, the sealing is accomplished via the sealing edges 26, 28. An effective sealing effect and sealing is achieved via the support tube 30 cooperating with the filter jacket 34, so that overall the filter element 18 achieves the sealing effect.

In terms of manufacture, the sealing edges 26, 28 of the filter element 18 are each formed by a circumferential weld 40 (see FIG. 2), which completely covers the front ends along the pleated folds of the filter jacket 34. The circumferential weld 40 is in this case by grinding or the like. reworked that the sealing edges 26, 28 run straight along a closed circumferential arc to ensure their sealing purpose.

The distributor device 22 has a distributor head 42 with a pressure plate 44 at its upper end. The distributor head 42 is guided within the housing 12 in a longitudinally movable manner within a cylindrical support receptacle 46. The filter element 18 encompasses the outer circumference of the mentioned distribution head 42 and is supported at one end on the underside of the pressure plate 44 and at the other end on a projection 48 of the support receptacle 46. The underside of the pressure plate 44 and the top of the projection 48 are also provided with an angle of inclination that corresponds to the angle of inclination of the sealing edges 26 and corresponds to 28 and is preferably 1 5 ° with respect to the horizontal.

However, it is also possible to design the underside of the pressure plate 44 with an inclination angle of 0 °. To seal the sealing gap 24, a sealing ring (not shown) can also be arranged between the sealing edge 26 of the filter element and the sealing surface of the distributor device 22.

For the relevant configuration, however, it is particularly advantageous to use a filter element according to FIG. 2a without a separate sealing ring. The same reference numerals are used for this modified embodiment of a filter element as for the previously presented filter element and this new embodiment is only explained in so far as it differs significantly from the previous embodiment. As shown in particular in the enlarged detail Y in FIG. 2a, the lower sealing edge 28 is arranged axially recessed relative to the support tube 30 when viewed in the direction of the figure. At the other end of the filter element 18, as the enlarged detail X shows, the sealing edge 26 is arranged to run flat, i.e. lying together in a horizontal plane with the associated free end of the support tube 30. The overall stiffness of the filter element 18 according to FIG. 2a is dimensioned such that, under the growing and finally constant contact pressure of the spinning head and in particular its pressure plate 44, the sealing gap closes 24 takes place visibly up to the maximum sealing effect and consequently a secure seal in the area of the circular weld seams, which essentially form the sealing edges 26, 28.

The outer circumference of the filter element 18 delimits with the support receptacle 46 a feed space 50 which is dimensioned volumetrically such that a possible dead space is kept small. The support tube 30 with the distributor head 42 in turn delimits a delivery space 52 for the plastic melt, wherein the delivery space 52 can also consist of individual longitudinal channels, which are arranged on the outer circumferential side of the distributor head 42 and can extend in the longitudinal direction over the entire height of the support tube 30. While the feed space 50 tapers conically from top to bottom as viewed in the direction of FIG. 1, the delivery space 52 widens conically from top to bottom. It has been shown that this leads to optimal flow conditions when flowing through the filter element 18 with a simultaneous reduction in dead space.

The distributor head 42 cooperates in the usual way with a control head 54, which is guided longitudinally in the housing 12 along the inner wall and, with an increasing feed movement in the direction of the distributor head 42, provides an edge seal 56 with respect to the housing 12. For the supply of the plastic melt to the pressure plate 44, the control head 54 has a central recess 58 and from there the plastic melt is distributed evenly over the top of the pressure plate 44. From there, the plastic melt enters the feed space 50 via a longitudinal channel guide 60 on the circumferential side Control head 54 is supported in relation to the distributor head 42 via a spring-elastic spacer 62 in the manner of a partial segment of a plate spring. The spacer in question can in turn be supported with its lower end accordingly on an edge flange of the support receptacle 46 or on the distributor head 42 for limiting the path of the control head 54.

During the infeed movement of the control head 54 from its right, non-actuated position to the left operating position, it therefore moves a predeterminable distance. If, after overcoming the free spring travel of the spacer 62, the relevant force in connection with the pressure force of the plastic melt on the pressure plate 44 of the distributor head 42 is moved downward in the same direction, this results in an increased clamping force on the sealing edges 26, 28 of the filter element 18 and the sealing gaps 24 as possible passages between the distributor head 42 and the filter element 18 or between it and the support receptacle 46 are securely closed. The elasticity of the filter element 18 clamped in this way results in the increased sealing effect with a dynamic deformation of the seal itself.

Claims

Patent claims

1 . Filter device for a spinning head (10) for the production of plastic threads, which has a housing (12) in which the plastic melt flows through a filter element (18) with a filter material (20) under pressure before it emerges from the spinnerets - A distribution device (22) depending on the strength of the

Melt pressure experiences an axial contact force, which acts on the sealing edges (26, 28) of the filter element (18) while sealing gaps (24) are closed, characterized in that the filter element (18) forms a replaceable structural unit with a support tube (30) with a wall side Has fluid passages (32) which is surrounded by the filter material (20), which at least at one end with its sealing edge (26) projects axially or is set back via the support tube (30).

2. Filter device for a spinning head (10) for the production of plastic threads, which has a housing (12) in which the plastic melt flows under pressure through a filter element (18) with a filter material (20) before it emerges from the spinnerets Via a distributor device (22), depending on the strength of the melt pressure, an axial contact force is exerted, which acts on the sealing edges (26, 28) of the filter element (18) while sealing gaps (24) are closed, characterized in that the filter element (18) to form an exchangeable unit, a support tube (30) with wall-side fluid passages (32), which is surrounded by the filter material (20), which has a flat sealing edge (26) at least at one end, and that the overall rigidity of the filter element (18) is selected such that the sealing gaps (24) are closed under the contact pressure due to the elasticity of the filter element (18) lies.

3. Filter device according to claim 1 or 2, characterized in that the filter material (20) from a pleated filter jacket (34) is formed from wire mesh, the adjacent opposite ends of which are connected to one another via a longitudinal weld seam.

4. Filter device according to claim 1, characterized in that the filter jacket (34) has a predeterminable elasticity, which supports the closing of the sealing gaps (24) over the sealing edges (26, 28) of the filter element (18) under the axial contact force.

5. Filter device according to one of claims 1 to 4, characterized in that at least one of the sealing edges (26,28) of the filter element (1 8) with respect to the end circular planes (36) of the support tube (30) by a predetermined angular amount, preferably is inclined from 0 ° to 40 °, in particular by 15 °, in the direction of the entry of the plastic melt into the spinning head (10).

6. Filter device according to one of claims 3 to 5, characterized in that the sealing edges (26, 28) of the filter element (18) are each formed by a circumferential weld seam (40) which completely covers the front ends of the filter jacket (34) .

7. Filter device according to claim 6, characterized in that the circumferential weld seam (40) is reworked such that the sealing edges (26, 28) run flat along a closed, folded circumferential arc.

8. Filter device according to one of claims 1 to 7, characterized in that the distributor device (22) has a distributor head (42) with a pressure plate (44) which can be moved longitudinally within the housing (12) within a support receptacle (46) is led, and that that Filter element (18) the outer circumference of the distributor head (42) is supported at one end on the pressure plate (44) and at the other end on the support receptacle (46).

9. Filter device according to claim 8, characterized in that the outer periphery of the filter element (18) with the support receptacle (46) delimit a feed space (50) and the support tube (30) with the distributor head (42) a discharge space (52) for the plastic melt .

10 Filter device according to claim 8 or 9, characterized in that the distributor head (42) cooperates with a control head (54) which is guided longitudinally in the housing (12) and with increasing feed movement in the direction of the distributor head (42) a seal (56) against the housing (12).

1 1. Filter device according to one of claims 1 to 10, characterized in that the plastic melt is a polymer melt and that the filter material (20) consists of a multi-layer wire mesh made of stainless steel.

12.Spinning head for the production of plastic threads, with a housing (12) which has a spinneret with a plurality of nozzle bores on an outlet side and which has a control head (54) with a melt inlet (58) on an inlet side, and with a distributor device ( 22) and a filter element (18) between the

Control head (54) and the spinneret, the distributor device (22) and the filter element (18) being held together by a melt pressure against a support seat (46), the filter element (18) having a sealing edge (28) on a sealing surface of the support seat (46) and with another sealing edge (26) on one

Sealing surface of the distributor device (22) abuts and the distributor device (22) with a pressure plate (44) on the filter element element (18) and with a distributor head (42) protrudes into the filter element (18) and the plastic melt flows through a filter material (20) of the filter element (18) under pressure before it emerges from the spinneret and by means of the distributor head (42) ι the spinneret is guided, characterized in that the filter element (18) on the inside towards the distributor head (42) to support the filter material (20) has a support tube (30) with wall-side fluid passages (32) and that between the support tube (30 ) and the distribution head (42) a delivery space (52) is formed.

1 3. Spinning head according to claim 12, characterized in that the delivery space (52) between the support tube (30) and the distributor head (42) is formed by a conical taper of the distributor head (42) towards the outlet side.

14. Spinning head according to claim 12 or 1 3, characterized in that the sealing surface of the distributor device (22) between the pressure plate (44) and the distributor head (42) is formed by an underside of the pressure plate (44).

15. Spinning head according to claim 14, characterized in that the underside of the pressure plate (44) is inclined by a predeterminable angular amount, preferably from 0 ° to 40 °, in particular by 1 5 °, in the direction of the exit of the plastic melt in the spinning head (10) .

16. Spinning head according to one of claims 12 to 15, characterized in that the support tube (30) and the filter material (20) are connected to form a cylindrical filter jacket (34), at the ends of which the sealing surfaces (26, 28) of the filter element (18 ) are trained.

1 7. Spinning head according to claim 1 6, characterized in that the filter material (20) at the end facing the pressure plate (44) with its sealing edge (26) protrudes axially over the support tube (30).

18. Spinning head according to claim 16 or 1 7, characterized in that the filter jacket (34) has a predetermined elasticity, the closing of the sealing gaps (24) via the sealing edges (26, 28) of the filter element (18) under the axial contact force. supported.

1 9. Spinning head according to one of claims 1 6 to 1 8, characterized in that the sealing edges (26, 28) of the filter element (18) are each formed by a reworked circumferential weld seam (40), which the front ends of the filter jacket (34) cover completely.

20. Spinning head according to one of claims 12 to 19, characterized in that the filter material (20) consists of a pleated wire mesh or a pleated fleece.