FILTER UNIT FOR AN EXTRUDER ASSEMBLY, FILTER ARRANGEMENT AND CORRESPONDING FILTER CHANGING DEVICE AND METHOD FOR PRODUCING SUCH A FILTER UNIT

Abstract

A filter unit for an extruder assembly comprises a support body with a hollow cylindrical wall section and a base section connected thereto, wherein the support body has a central longitudinal axis and delimits an inner space, wherein the hollow cylindrical wall section has a plurality of through openings opening into the inner space and forms an outlet opening for a molten plastic opposite the base section; and a displacement element for displacing the molten plastic which has entered the inner space, in particular via the through openings, substantially in the direction of the central longitudinal axis, wherein the displacement element and the support body are configured and/or produced in one piece, as well as filter arrangement with a plurality of such filter units, filter changing device with at least two filter arrangements and method for producing such a filter unit.

Claims

1. A filter unit for an extruder assembly, comprising: a support body with a hollow cylindrical wall section and a base section connected thereto, wherein the support body has a central longitudinal axis and delimits an inner space, wherein the hollow cylindrical wall section has a plurality of through openings extending into the inner space and forms an outlet opening for a molten plastic opposite the base section; and a displacement element for displacing the molten plastic which has entered the inner space, in particular via the through openings, substantially in the direction of the central longitudinal axis, wherein the displacement element and the support body are configured and/or produced in one piece.

2. The filter unit according to claim 1, wherein the displacement element is arranged or configured in the inner space and/or on the base section.

3. The filter unit according to claim 1, wherein the displacement element is configured to be substantially conical and/or cone-shaped and/or partially cone-shaped and/or spherical and/or partially spherical at least in some sections, and/or wherein the base surface of the displacement element is formed and/or defined by the base section.

4. The filter unit according to claim 1, wherein the displacement element is arranged or configured to be concentric to the central longitudinal axis.

5. The filter unit according to claim 1, wherein the displacement element has a surface and/or contour, such as casing surface and/or casing contour, with one or more surface sections and/or contour sections, such as casing surface sections and/or casing contour sections, wherein the one or more surface sections or contour sections taper in the direction of the central longitudinal axis, in particular conically, and/or extend obliquely and/or relative to the central longitudinal axis, in particular at an angle.

6. The filter unit according to claim 5, wherein the plurality of surface sections or contour sections extend at different angles obliquely and/or relative to the central longitudinal axis, wherein the angle of a radially outer surface section or contour section is greater than the angle of a radially inner surface section or contour section.

7. The filter unit according to claim 1, wherein the through openings of the wall section opening into the inner space all have the same diameter.

8. The filter unit according to claim 1, wherein the support body and the displacement element are produced from a substantially non-weldable steel, in particular a hot work alloy steel such as a hot work high-alloy steel.

9. The filter unit according to claim 1, wherein the ratio of the active filter area to the casing surface of the support body, in particular of the wall section of the support body, is about 0.15 to 0.65.

10. The filter unit according to claim 1, wherein the ratio of the wall thickness of the support body, in particular of the wall section of the support body, to a ratio of diameter, such as outer diameter, of the support body, in particular of the wall section of the support body, squared to the length, in particular in the direction of the central longitudinal axis, of the support body, in particular of the wall section of the support body, is about 0.1 to 0.6.

11. A filter arrangement for an extruder assembly with a filter support, which has a support central longitudinal axis and a plurality of support through openings extending in the direction of the support central longitudinal axis, wherein in the region of each of the support through openings the filter unit according to claim 1 is attached and/or can be attached respectively in a detachable manner to the filter support.

12. A filter changing device for an extruder assembly, comprising: a housing; at least one melt channel extending in the housing; at least one guide bore extending transversely to the at least one melt channel and through the latter in the housing; at least one slide element arranged in the at least one guide bore; and at least two filter arrangements according to claim 11 arranged and/or mounted spaced apart on the at least one slide element.

13. A method for producing the filter unit according to claim 1, comprising: producing a blind hole in an, in particular cylindrical, steel blank, in particular substantially non-weldable steel blank; and producing a displacement element inside the blind hole, in particular on or in the blind hole bottom or blind hole base.

14. The method according to claim 13, wherein the production of the blind hole and the displacement element is performed in one step or in consecutive steps.

15. The method according to claim 13, further comprising enlarging, in particular enlarging by machining, such as reaming, drilling or turning, the blind hole before and/or after producing the displacement element.

16. The method according to claim 13, wherein the production of the displacement element is performed by a drilling rod which has at least one cutting plate, such as an indexable insert, and/or wherein the at least one cutting plate has a geometry which is dependent on the surface and/or contour of the displacement element.

17. The method according to claim 16, wherein the drilling rod has a number of cutting plates, such as indexable inserts, which is dependent on the surface and/or contour of the displacement element and/or which corresponds to the number or twice the number of surface sections or contour sections of the displacement element, and/or in that the drilling rod has 1 to 10 cutting plates.

Description

[0031] Exemplary embodiments of the disclosure are described in more detail in the following with reference to the Figures, which show in schematic form and by way of example:

[0032] FIG. 1 a side view of a filter unit;

[0033] FIG. 2 a sectional view along A-A of the filter unit according to FIG. 1;

[0034] FIG. 3 a sectional view along B-B of the filter unit according to FIG. 1;

[0035] FIG. 4 a front view of the filter unit according to FIG. 1;

[0036] FIG. 5 a partial sectional view along E-E of the filter unit according to FIGS. 1 and 4;

[0037] FIG. 6 a detailed view X of the filter unit according to FIGS. 1 and 5;

[0038] FIG. 7 a perspective view of a filter arrangement;

[0039] FIG. 8 a side view of the filter arrangement according to FIG. 7;

[0040] FIG. 9 a front view of the filter arrangement according to FIG. 7;

[0041] FIG. 10 a sectional view along A-A of the filter arrangement according to FIGS. 7 and 9;

[0042] FIG. 11 a perspective view of a filter changing device;

[0043] FIG. 12 a plan view of the filter changing device according to FIG. 11;

[0044] FIG. 13 a rear view of the filter changing device according to FIG. 11;

[0045] FIG. 14 a sectional view along A-A of the filter changing device according to FIGS. 11 and 13; and

[0046] FIG. 15 a flowchart for a method for producing a filter unit.

[0047] FIGS. 1 to 6 show different views of a filter unit 100, which is configured for filtering a molten plastic. The filter unit 100 comprises a support body 102 with a hollow cylindrical wall section 104 and a base section 106 connected thereto. The support body 102 has a central longitudinal axis 108 and delimits an inner space 110. The hollow cylindrical wall section 104 has a plurality of through openings 112 opening into the inner space 110 and forms an outlet opening 114 for the molten plastic opposite the base section 106. The through openings 112 of the wall section 104 opening into the inner space 110 all have the same bore diameter 120. The through openings 112 are formed as through bores 112 in the present exemplary embodiment.

[0048] The base section 106 is arranged on the upstream side (right side of FIG. 1) of the support body 102 and the outlet opening 114 is arranged on the downstream side (left side of FIG. 1) of the support body 102. A filter element, such as a filter fleece, (not shown in FIGS. 1 to 6) is arranged around the wall section 104, for example pushed on. The molten plastic is pushed through the filter element and then passes through the through openings 112 into the inner space 110, in which the molten plastic then flows to the outlet opening and exits there again.

[0049] The ratio of the active filter area to the outer casing surface of the wall section 104 of the support body 102 is about 0.15 to 0.65, in particular about 0.25 to 0.5, in particular about 0.38. The active filter area is the total area of all through bores 112 or all cross-sectional areas 118 of the through bores 112. The active filter area can thus be calculated or defined by multiplying the number of through bores 112 with the cross-sectional area 118 of a through bore 122, as all through bores 112 have the same bore diameter 120.

[0050] The ratio of the wall thickness 122 of the wall section 104 of the support body 102 to a ratio of the diameter 124, such as outer diameter 124, of the wall section 104 of the support body 102, squared to the length 126 of the wall section 104 of the support body 102 in the direction of the central longitudinal axis 108 is about 0.1 to 0.6, in particular about 0.2 to 0.3, in particular about 0.25.

[0051] The filter unit 100 also comprises a displacement element 116 for displacing the molten plastic that has entered the inner space 110 via the through openings 112 substantially in the direction of the central longitudinal axis 108. As shown in FIGS. 5 and 6, the displacement element 116 and the support body 102 are formed in one piece and produced from one piece or part. A substantially non-weldable steel, in particular alloy steel, such as high-alloy, hot-work steel is used to produce the one-piece support body 102 with displacement element 116.

[0052] The displacement element 116 is arranged or formed in the inner space 110 and on the base section. As shown in FIG. 5, the displacement element 116 is substantially conical at least in sections, wherein the base surface of the displacement element 116 is formed by the base section 106. To allow an even flow of the molten plastic, the displacement element 116, as shown in FIGS. 2, 3 and 5, is arranged or formed concentrically to the central longitudinal axis 108.

[0053] The displacement element 116 further comprises a casing surface 128 or casing contour 128 with a plurality of casing surface sections 130a, 130b, 130c or casing contour sections 130a, 130b, 130c. The casing surface sections 130a, 130b, 130c or casing contour sections 130a, 130b, 130c taper substantially conically in the direction of the central longitudinal axis 108 and extend at different angles 132a, 132b, 132c obliquely and relative to the central longitudinal axis 108, wherein the angle of a radially outer casing surface section 130a, 130b, 130c or casing contour section 130a, 130b, 130c is greater than the angle of a radially inner casing surface section 130a, 130b, 130c or casing contour section 130a, 130b, 130c. In the present exemplary embodiment according to FIGS. 5 and 6 the radially outer casing surface section 130c or casing contour section 130c has a greater angle 132c relative to the central longitudinal axis 108 than the two radially further inner casing surface sections 130a, 130b or casing contour sections 130a, 130b. The radially inner casing surface section 130a or casing contour section 130a has a smaller angle 132a relative to the central longitudinal axis 108 than the two radially further outerlying casing surface sections 130b, 130c or casing contour sections 130b, 130c. In this way the casing surface or contour of the displacer element 116 is specifically adapted to enable an optimum flow and conveyance of the filtered molten plastic in the direction of the central longitudinal axis 108 to the outlet opening 114. The flow behaviour of the molten plastic and the rheological ratios can be optimally adjusted by selecting suitable angles 132a, 132b, 132c, in particular to prevent deposits of products on the inflow side. The capacity for chip removal during the production process can also be improved by a suitable selection of the angles 132a, 132b, 132c.

[0054] The support body 102 further comprises a holding section 134 on its downstream side, which is configured for attaching the filter unit 100 to a filter support. The holding section 134 can have an external thread complementary to a thread of the filter support for example (not shown in FIGS. 1 to 6), so that the support body 102 can be screwed to the filter support.

[0055] FIGS. 7 to 10 show various views of a filter arrangement 200, which is configured for filtering the molten plastic and is used in a filter changing device. The filter arrangement 200 has a filter support 202 with a support central longitudinal axis 204 and, as shown in FIG. 10, has a plurality of support through openings 206 extending in the direction of the support central longitudinal axis 204. In the region of the support through openings 206 a filter unit 100 is attached respectively detachably to the filter support 202, in particular screwed into an internal thread 208 by means of the holding section 134 of the filter unit 100. The filter units 100 are formed as described above and/or in the following. A filter element 210, for example filter fleece 210, is pushed respectively onto the support bodies 102 of the filter units 100 and fixed by means of a cover element 212 to the respective wall section 104 of the support body 102. The cover element 212 can be screwed to the support body 102, for example to its base section 106 and/or displacement element 116.

[0056] As shown in FIG. 9, the filter support 202 is circular in cross-section. The support central longitudinal axis 204 extends in the conveying direction and parallel to the central longitudinal axes 108 of the filter units 100, as shown in FIGS. 8 and 10. A first support through opening 206 is arranged concentrically to the support central longitudinal axis 204. A group of, here six, second support through openings 206 is arranged along a first circle concentric to the support central longitudinal axis 204, wherein the second support through openings 206 are arranged distributed evenly along the first circle. A further group of, here twelve, third support through openings 206 is arranged along a second circle concentric to the support central longitudinal axis 204, wherein the second circle surrounds the first circle. The third support through openings 206 are also distributed evenly along the second circle.

[0057] In addition, reference is also made in particular to FIGS. 1 to 6 and the associated description.

[0058] FIGS. 7 to 10 show different views of a filter changing device 300 for an extruder assembly. The filter changing device 300 comprises a housing 302 and two melt channels 304 extending in the housing 302, which open into or pass into a common inlet channel 306 or outlet channel 306 at the upstream melt inlet and at the downstream melt outlet respectively. The filter changing device 300 further comprises two guide bores 310, wherein each guide bore 310 extends transversely, for example substantially perpendicularly, to the respective melt channel 304 and through the latter into the housing 302. The guide bores 310 also extend transversely, for example substantially perpendicularly, to the conveying direction.

[0059] The filter changing device 300 has two cylindrical slide elements 312, wherein a slide element 312 is mounted displaceably in a guide bore 310 respectively. Furthermore, the filter changing device 300 comprises an actuating drive 314, which is configured to displace the slide elements 312 independently of one another transversely, for example substantially perpendicularly, to the conveying direction and transversely, for example substantially perpendicularly, to the respective melt channel 304. The at least one actuating drive 314 can be configured to be hydraulic and/or electromechanical for example.

[0060] In the present exemplary embodiment according to FIGS. 11 to 14, the filter changing device 300 comprises four filter arrangements 200. The filter arrangements 200 are configured as described above and/or in the following. Two filter arrangements 200 are arranged spaced apart from one another respectively on a slide element 312. For this purpose, two continuous receiving openings 316 are formed respectively in the slide elements 312, in each of which receiving opening a filter arrangement 200 is mounted and/or secured replaceably. The two receiving openings are spaced apart transversely, for example substantially perpendicularly, to the conveying direction and transversely, for example substantially perpendicularly, to the respective melt channel 304 such that one of the filter arrangements 200 is arranged outside the housing 302 when the respective other filter arrangement 200 is located in the melt channel 304.

[0061] In addition, reference is also made in particular to FIGS. 1 to 10 and the associated description.

[0062] FIG. 15 shows schematically a flowchart for a method for producing a filter unit 100.

[0063] In step S1 a blind hole is drilled and/or milled in an, in particular cylindrical, steel blank, for example a substantially non-weldable steel blank. The drilling and/or milling of the blind hole is performed along the central longitudinal axis 108.

[0064] In step S2 the blind hole is reamed, i.e. reamed out, for example with a reamer. The blind hole can be flushed out prior to the reaming.

[0065] In step S3 a displacement element 116 is drilled and/or milled inside the blind hole, in particular into the blind hole bottom or blind hole base. The drilling and/or milling of the displacement element 116 can be performed by using a drilling rod. The drilling rod can comprise a conical drill or can be configured in this way. The drilling rod can comprise at least one cutting plate, such as an indexable insert. The at least one cutting plate can have a geometry which is dependent on the surface and/or contour of the displacement element 116. The drilling rod can comprise a number of cutting plates, such as indexable inserts. The number of cutting plates can be dependent on the surface and/or contour of the displacement element 116. The number of cutting plates can be equal to or twice the number of surface sections or contour sections of the displacement element 116. For example, the drilling rod can comprise 1 to 10, in particular 2 to 7, in particular 3 to 5 cutting plates. There can be an even or odd number of cutting plates. The cutting plates can have and/or define the angle 132a, 132b, 132c of the surface sections or contour sections.

[0066] In addition, reference is also made in particular to FIGS. 1 to 14 and the associated description.

[0067] The term “can” is used in particular to refer to optional features of the disclosure. Thus, there are also further developments and/or exemplary embodiments of the disclosure, which, additionally or alternatively, have the respective feature or the respective features.

[0068] From the combinations of features disclosed herein, isolated features can also be selected if necessary and used in combination with other features to delimit the claimed subject-matter, while resolving any structural and/or functional relationship that may exist between the features. The sequence and/or number of steps of the method can be varied.

TABLE-US-00001 List of reference signs 100 filter unit 102 support body 104 wall section 106 base section 108 central longitudinal axis 110 inner space 112 through openings 114 outlet opening 116 displacement element 118 cross-sectional areas 120 bore diameter 122 wall thickness 124 outer diameter 126 length 128 casing surface / casing contour 130a casing surfaces sections / casing contour sections 130b casing surface sections / casing contour sections 130c casing surface sections / casing contour sections 132a angle 132b angle 132c angle 134 holding section 136 external thread 200 filter arrangement 202 filter support 204 support central longitudinal axis 206 support through openings 208 inner thread 210 filter elements 212 cover elements 300 filter changing device 302 housing 304 melt channels 306 inlet channel 308 outlet channel 310 guide bore 312 slide elements 314 actuating drive 316 receiving openings S1 drilling and/or milling the blind hole S2 reaming the blind hole S3 drilling and/or milling the displacement element