METHOD FOR MOLDING A SEALING DEVICE ONTO AN END FOLD OF A BELLOWS, CASTING SHELL ASSEMBLY AND FILTER ELEMENT

Abstract

In a method for molding a sealing device onto an end fold of a pleated bellows, wherein the end fold comprises an outer side and an inner side, the pleated bellows arranged in a casting shell assembly is embedded in a curable sealing material, limited at a rim of the pleated bellows by a casting chamber formed by the casting shell assembly. Expansion of the curable sealing material is reduced or prevented by a limitation element contacting the inner side of the end fold. A casting shell assembly has top and bottom casting shell parts forming a casting chamber to mold a sealing device onto the end fold of the pleated bellows by a sealing material. The bottom casting shell part has a channel for receiving the sealing material. The channel has an upwardly projecting limitation element for engaging an inner side of the end fold.

Claims

1. A method for molding a sealing device onto an end fold of a pleated bellows folded in a zigzag shape, wherein the end fold comprises an outer side and an inner side, the method comprising: embedding in a curable sealing material the pleated bellows arranged in a casting shell assembly, wherein embedding is limited at a rim side of the pleated bellows by a casting chamber formed by the casting shell assembly; reducing or preventing an expansion of the curable sealing material by a limitation element contacting the inner side of the end fold.

2. The method according to claim 1, wherein the casting shell assembly comprises a top casting shell part and a bottom casting shell part, wherein the method further comprises at least one of the steps: arranging the pleated bellows in or at the top casting shell part; introducing the curable sealing material in an uncured state into a circumferentially extending channel of the bottom casting shell part, wherein the limitation element projects upwardly from the bottom casting shell part; arranging the top casting shell part with the pleated bellows on the bottom casting shell part such that the limitation element contacts at least partially the inner side of the end fold; curing of the sealing material to form the sealing device; removing the pleated bellows with the sealing device formed thereon from the casting shell assembly.

3. The method according to claim 1, further comprising arranging the limitation element between the inner side of the end fold and a neighboring fold section of the pleated bellows neighboring the end fold so as to prevent the curable sealing material from expanding in a direction toward the neighboring fold section.

4. The method according to claim 1, wherein the curable sealing material comprises a material expanding upon curing.

5. The method according to claim 1, wherein the material expanding upon curing is a plastic material or a PUR foam.

6. The method according to claim 1, further comprising forming the casting chamber such that the curable sealing material at least partially covers the outer side and the inner side of the end fold.

7. The method according to claim 1, further comprising holding and positioning the pleated bellows at a top casting shell part of the casting shell assembly by spring elements provided at the top casting shell part.

8. The method according to claim 1, wherein the limitation element extends across at least 30% of a length of the end fold.

9. A casting shell assembly comprising: a top casting shell part and a bottom casting shell part forming a casting chamber configured to mold a sealing device onto an end fold of a pleated bellows folded in a zigzag shape by a curable sealing material; the bottom casting shell part comprising a channel configured to receive the curable sealing material, wherein the channel comprises an upwardly projecting limitation element configured to engage an inner side of the end fold.

10. The casting shell assembly according to claim 9, wherein the limitation element is a spring element.

11. The casting shell assembly according to claim 9, wherein the casting chamber is configured such that between the limitation element and a corresponding wall of the top casting shell part an upwardly open slot is formed and configured to receive the end fold.

12. A filter element obtained by the method of claim 1.

13. A filter element manufactured in a casting shell assembly according to claim 9.

14. A filter element comprising: a pleated bellows of a filter medium folded in a zigzag shape and comprising at least one end fold with an inner side and an outer side; a sealing device molded at a rim side onto the pleated bellows; wherein the sealing device covers at least partially a rim section of the outer side and of the inner side of the at least one end fold; and wherein the sealing device is spaced from a neighboring fold section of the pleated bellows neighboring the at least one end fold at least across a substantial length of the neighboring fold section.

15. The filter element according to claim 14, wherein the neighboring fold section is substantially free of a cured sealing material of the sealing device.

16. The filter element according to claim 14, wherein the at least one end fold is a fold section delimiting the pleated bellows outwardly, wherein the outer side of the at least one end fold forms an outer rim of the pleated bellows, and wherein the inner side of the at least one end fold is positioned opposite the outer side of the at least one end fold, wherein the neighboring fold section is a fold section folded at a fold edge relative to the at least one end fold.

17. The filter element according to claim 14, wherein the neighboring fold section is configured to be flowed through for filtration of a fluid to be filtered.

18. The filter element according to claim 14, wherein fold sections of the pleated bellows adjacent to the neighboring fold section are substantially free of the sealing device.

19. The filter element according to claim 14, wherein a cured sealing material of the sealing device is comprised of a material which expands upon curing.

20. The filter element according to claim 19, wherein the material which expands upon curing is a plastic material or a PUR foam.

21. The filter element according to claim 19, wherein the cured sealing material of the sealing device covers at least partially the outer side and the inner side of the at least one end fold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 shows a schematic perspective view of a pleated bellows folded in a zigzag shape, used in a method for molding a sealing device according to a first embodiment, and of the molded-on sealing device.

[0057] FIG. 2 shows a partial view of FIG. 1.

[0058] FIG. 3 shows a cross section view of a casting shell assembly used in the method and of the pleated bellows in a state arranged on each other and filled with a sealing material during the process.

[0059] FIG. 4 shows a view of a bottom casting shell part and of a top casting shell part of the casting shell assembly of FIG. 3.

[0060] FIG. 5 shows a schematic perspective principle illustration of the casting shell assembly and of a filter element obtained by the method according to the first embodiment.

[0061] FIG. 6 shows a partial cross section view of the sealing device molded onto the pleated bellows in accordance with the method according to the first embodiment.

[0062] FIG. 7 shows a cross section view of a bottom casting shell part of a casting shell assembly which is used in a method for molding a sealing device onto the pleated bellows according to a second embodiment.

[0063] FIG. 8a shows a schematic perspective view of a filter element according to the invention.

[0064] FIG. 8b shows a schematic detail view of the filter element of FIG. 8a with cut-away corner.

[0065] In the Figures, same or functionally the same elements, if nothing to the contrary is indicated, are provided with the same reference characters.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0066] In the following, with the aid of FIGS. 1 to 6, a method for molding a sealing device 2 onto a pleated bellows 1 folded in a zigzag shape according to a first embodiment is described.

[0067] FIG. 1 shows a schematic perspective view of the pleated bellows 1 folded in a zigzag shape which is used in the method and the molded-on sealing device 2. Oppositely positioned lateral strips 6 are attached to the pleated profiles of the pleated bellows 1. The lateral strips 6 form together with the end folds 5 a circumferentially extending frame. FIG. 2 shows a partial view of FIG. 1.

[0068] As illustrated in FIG. 2, the pleated bellows 1 is a filter medium with a plurality of fold sections 3 folded at fold edges 4. The pleated bellows 1 comprises an end fold 5 which forms a fold section delimiting the pleated bellows 1 outwardly. The end fold 5 comprises an outer side 5A and an inner side 5B oppositely positioned to the outer side 5A. In particular, the outer side 5A forms an outer rim of the pleated bellows 1. The pleated bellows 1 comprises a fold section 13 neighboring the end fold 5.

[0069] The fold sections 3, including the end fold 5 and the neighboring fold section 13, are fixed by means of the lateral strip 6 which is attached to the rim-side pleated profiles of the fold sections 3, 5, 13. The lateral strip 6 is illustrated only in FIG. 1 for reasons of clarity.

[0070] Moreover, sealing device 2, which is molded onto the pleated bellows 1 by means of the method disclosed in the following, is illustrated in FIGS. 1 and 2. The sealing device 2 is molded onto the end fold 5, in particular the inner side 5B and the outer side 5A. Aside from the end fold 5, the sealing device 2 covers no additional fold sections 3 of the pleated bellows 1, in particular also does not cover the neighboring fold section 13.

[0071] FIG. 3 shows a cross section view of a casting shell assembly 7 used in the method and of the pleated bellows 1 in a state arranged on each other and filled with a sealing material 10 during the process. FIG. 4 shows a bottom casting shell part 9 of the casting shell assembly 7 of FIG. 3. FIG. 5 shows a schematic perspective view of the principle illustration of the casting shell assembly 7 and of a filter element obtained by means of the method, in other words of the pleated bellows 1 with molded-on sealing device 2.

[0072] The casting shell assembly 7 comprises, as illustrated in FIGS. 3 to 5, a top casting shell part 8 and the bottom casting shell part 9.

[0073] In a first step of the method, the pleated bellows 1 is arranged in the top casting shell part 8. The pleated bellows 1 is in particular arranged such in the top casting shell part 8 that the outer side 5A of the end fold 5 of the pleated bellows 1 is arranged at a lateral contact surface 20 of the top casting shell part 8. For reasons of clarity, the inner side 5B and the outer side 5A are provided only in FIGS. 2 and 6 with a reference character. The top casting shell part 8 comprises, for example, spring elements 14. As indicated schematically in FIG. 3, the spring elements 14 are arranged in the top casting shell part 8. For example, the spring elements 14 are arranged at oppositely positioned inner walls in the top casting shell part 8. Upon arrangement of the pleated bellows 1 in the top casting shell part 8, the spring elements 14 engage the outer sides of the pleated bellows 1. The spring elements 14 can engage in particular at the outer side 5A, at rim-side pleated profiles and/or the lateral strip 6 of the pleated bellows 1. In FIG. 3, it is shown in an exemplary fashion how a spring element 14 engages at the outer side 5A of the pleated bellows 1. In FIG. 5, it is indicated by four arrows 15 at the top casting shell part 8 how the spring elements 14 can exert circumferential clamping forces on the pleated bellows 1. The spring elements 14 hold the pleated bellows 1 at the top casting shell part 8 so that the pleated bellows 1 is held in position at the top casting shell part 8, in particular when arranging the casting shell parts 8 and 9.

[0074] The here used directions “top” and “bottom” relate to the manufacturing process. The sealing device 2 is molded during the method onto a bottom edge of the pleated bellows 1, as illustrated in FIGS. 1, 2, and 6. In the finished product, the sealing device 2 can however be located at a top edge of the pleated bellows 1, as illustrated in FIG. 5.

[0075] In a second step of the method, the curable sealing material 10 in the liquid state is filled into the bottom casting shell part 9. The bottom casting shell part 9 comprises a circumferentially extending channel 16, as shown in cross section in FIG. 3. The liquid sealing material 10, for example, a PUR material, is filled into the circumferentially extending channel 16. For example, the liquid sealing material 10 is metered into the channel 16 by means of a metering head (not illustrated) guided by a robot.

[0076] The bottom casting shell part 9 comprises a limitation element 11 which in this embodiment is embodied as one part together with the bottom casting shell part 9 and projects thereat upwardly, as illustrated in cross section in FIG. 3. The limitation element 11 forms a rim 21 of the circumferentially extending channel 16 which, for example, projects farther upwardly than a second rim 22 of the channel 16. Here, the rim 21 is an inner rim of the circumferentially extending channel 16 and the rim 22 is an outer rim of the channel 16.

[0077] The bottom casting shell part 9 with the limitation element 11 is designed such and a quantity of filled-in liquid sealing material 10 is metered such that the limitation element 11 at the channel 16 projects upwardly past the filled-in liquid sealing material 10 after filling in the liquid sealing material 10 and prior to curing of the sealing material 10.

[0078] The limitation element 11 serves as a separation wall which separates the end fold 5 from the neighboring fold section 13 during the subsequent curing of the filled-in sealing material 10. In particular a wall 23 of the limitation element 11 forms a contour which prevents the liquid sealing material 10 from expanding during curing.

[0079] In a third step of the method, the top casting shell part 8 with the pleated bellows 1 is arranged at the bottom casting shell part 9 such that the limitation element 11 at least partially contacts the end fold 5 at the inner side.

[0080] In particular, upon arranging the casting shell parts 8 and 9 on each other, the limitation element 11 is introduced between the end fold 5 and the neighboring fold section 13 so that the limitation element 11 contacts the inner side 5B of the end fold 5. The limitation element 11 can push in this context the end fold 5 against the top casting shell part 8, in particular against the lateral contact surface 20 of the top casting shell part 8. Since the limitation element 11 is brought into direct contact with the inner side 5B of the end fold 5, the limitation element 11 delimits at the inner side 5B an expansion of the sealing material 10 in upward direction upon subsequent curing of the sealing material 10. Due to the limitation element 11, in particular the end fold 5 is separated from the neighboring fold section 13 and kept at a distance so that an expansion to the neighboring fold section 13 can be prevented during the subsequent curing of the sealing material 10.

[0081] By arranging the top casting shell part 8 at the bottom casting shell part 9, a casting chamber 12 for expansion of the sealing material 10 during curing is formed between them. The casting chamber 12 comprises in particular a volume that is formed by the circumferentially extending channel 16 into which the liquid sealing material 10 is filled. In addition to the volume which is formed by the channel 16, the casting chamber 12 comprises a top expansion region for expansion of the curing sealing material 10. The top expansion region comprises between the limitation element 11 and a corresponding wall 18 of the top casting shell part 8 an upwardly open slot 19 in which the end fold 5 is present, as can be seen in FIG. 3.

[0082] Due to the arrangement of the top casting shell part 8 with the pleated bellows 1 at the bottom casting shell part 9, the end fold 5 of the pleated bellows 1 is located between the contact surface 20 of the top casting shell part 8 and the limitation element 11 of the bottom casting shell part 9 which form the slot 19, as can be seen in FIG. 4.

[0083] In a fourth step of the method, the sealing material 10 is cured with a volume increase for forming the sealing device 2.

[0084] A quantity of filled-in liquid sealing material 10 is measured such that the sealing material 10 expands upwardly upon curing. In particular, it expands upwardly into the slot 19 in which the end fold 5 is arranged. In this way, the sealing material 10 expands at the outer side 5A and the inner side 5B of the end fold 5 so that the outer side 5A and the inner side 5B at least partially are covered by the expanding sealing material 10. FIG. 6 shows a partial cross section view of the sealing device 2 which is molded onto the pleated bellows 1 according to the method.

[0085] Upon curing, an expansion of the sealing material 10 at the inner side 5B in upward direction and in direction toward the neighboring fold section 13 is limited by the limitation element 11 which is contacting the inner side 5B of the end fold 5 and, for example, pushes the end fold 5 against the top casting shell part 8. In this way, a top section of the outer side 5A, a top section of the inner side 5B, the neighboring fold section 13, and the further fold sections 3 remain free of sealing material 10. After curing, the top casting shell part 8 is removed and the filter element comprised of pleated bellows 1 and molded-on sealing device 2 is removed from the bottom casting shell part 9.

[0086] Therefore, with the method, a filter element can be manufactured in which the sealing device 2 is molded onto the pleated bellows 1 such that it partially covers the inner side 5B and the outer side 5A and is fixedly connected to the end fold 5 of the pleated bellows 1 in this coverage region. Since the sealing device 2 does not cover the upper sections of the inner side 5B and of the outer side 5A, they are free of the sealing device 2 and can be used for a filtration of the fluid. Moreover, also the neighboring fold section 13 and the further fold sections 3 are free of the sealing device 2 and can be used for a filtration of the fluid. Consequently, with the method, a filter element can be manufactured in which all fold sections 3, 13 except for the end fold 5 are completely available for a fluid filtration.

[0087] FIG. 7 shows a cross section view of a bottom casting shell part 9′ of a casting shell assembly which is used in a method for molding a sealing device 2′ onto a pleated bellows 1 according to a second embodiment. In the following, the “apostrophed” reference characters are used for explanation of the second embodiment even if they are not explicitly shown in the Figures. Elements with the same numbers correspond to those of the first embodiment. The method according to the second embodiment as well as the casting shell assembly 7′ used for this purpose are similar to the method according to the first embodiment and the casting shell assembly 7 used therein. Also, the pleated bellows 1 is similar to the pleated bellows 1 used in the method according to the first embodiment. In the following, mostly features are disclosed which differ from those of the first embodiment.

[0088] As illustrated in FIG. 7, the bottom casting shell part 9′ used in the method according to the second embodiment comprises a limitation element in the form of a spring 17 arranged thereat.

[0089] The spring 17 is arranged at an inner rim 24 of a channel 16′ and projects past the rim 24 in upward direction.

[0090] In the method according to the second embodiment, a top casting shell part 8′ (not illustrated) is arranged at the bottom casting shell part 9′. The top casting shell part 8′ according to the second embodiment is similar to the top casting shell part 8 according to the first embodiment. As in the method according to the first embodiment, a pleated bellows 1′ (not illustrated) similar to the pleated bellows 1 is arranged at the top casting shell part 8′. The pleated bellows 1′ according to the second embodiment comprises also an end fold 5′ with an inner side 5B′ and an outer side 5A′, a neighboring fold section 13′, and a further fold section 3′. When arranging the top casting shell part 8′ at the bottom casting shell part 9′, the spring 17 is introduced between the end fold 5′ and the neighboring fold section 13′ of the pleated bellows 1′. The spring 17 tapers in upward direction so that the spring 17 can be inserted easily between the end fold 5′ and the neighboring fold section 13′ even when they have a minimal distance relative to each other. Moreover, upon arranging the spring 17 between the end fold 5′ and the neighboring fold section 13′, the spring 17 is pushed against the inner side 5B′ of the end fold 5′ by a restoring force of the spring 17. In this manner, the end fold 5′ is pushed against the top casting shell part 8′ and is held at a distance to the neighboring fold section 13′. In this way, the limitation element in the form of the spring 17 can be introduced in an easy way between the end fold 5′ and the neighboring fold section 13′. Moreover, due to the spring 17 pushing against the inner side 5B′, an expansion of the sealing material during curing in upward direction along the inner side 5B′ can be limited very well. In this manner, a sealing device 2′ can be molded onto the pleated bellows 1′ such that only a small portion of the pleated bellows 1′ is covered by the sealing device 2′. In this way, a filter element with a high filtration performance can be produced.

[0091] In FIGS. 8a and 8b, a filter element manufactured according to the method according to the invention is illustrated. The filter element comprises a pleated bellows 1 with lateral strips 6 and circumferentially extending sealing device 2. In FIG. 8b, the filter element is illustrated with cut-away corner so that it can be seen how the end fold 5 is embedded in the sealing device 2. The sealing device 2 engages about the end fold 5 at an inner side and at an outer side.

EMPLOYED REFERENCE CHARACTERS

[0092] 1, 1′ pleated bellows [0093] 2, 2′ sealing device [0094] 3, 3′ fold sections [0095] 4 fold edges [0096] 5, 5′ end fold [0097] 5A, 5A′ outer side [0098] 5B, 5B′ inner side [0099] 6 lateral strip [0100] 7, 7′ casting shell assembly [0101] 8, 8′ top casting shell part [0102] 9, 9′ bottom casting shell part [0103] 10 sealing material [0104] 11 limitation element [0105] 12 casting chamber [0106] 13, 13′ neighboring fold section [0107] 14 spring elements [0108] 15 clamping force [0109] 16, 16′ circumferentially extending channel [0110] 17 spring [0111] 18 wall [0112] 19 slot [0113] 20 lateral contact surface [0114] 21 rim [0115] 22 rim [0116] 23 wall [0117] 24 rim