DE3925511C1 - Low cost filter with good stability - filter element has zigzag folds and surrounding frame using 2 mould halves - Google Patents

Abstract

A filter consists of a filter element in zigzag folds and a surrounding frame in which the needs of the filter element are embedded. This frame is made by using two halves of a mould which zigzag protections which seal against the filter element. Partitions define the space for the frame into which the filter elements are allowed to intrude and which is filled with PU foam mix, using an x-y coordinate distributor which applies no pressure. A cover plate is finally placed over this space. ADVANTAGE - Filter can be produced at low cost and has a good stability, permeability and filtering performance.

Description

The invention relates to a method for producing a Filters with a zig-zag zag-shaped filter element and one that Filter element surrounding frame, the filter element in a first mold half of a two mold halves having casting mold is introduced, the filter element bounding towards the frame and encircling the filter element Area section between the first and the second Half of the mold is sealed by means of a seal, and in the through the seal in the mold halves defined cavity a foaming plastic Reaction mixture is introduced after the reaction  forms the frame firmly connected to the filter element, and an apparatus for performing this method.

Such a method and a device for carrying it out this method is described in DE-OS 23 27 522. There is a along the edges of the Filter element extending and through the folding back of the zigzag-shaped pleated filter element elastic compressible sealing strip between the one open Side of the filter element and the mold along which the Frame inserting filter element inserted. Here are preferably for the two open sides of the filter element two such sealing strips each provided preferably over the entire length of the folded edges of the Extend filter element. Along the folded edges of the Filter element can there the sealing function of Sealing strips still folded through along one Embossed profile wave extending edge of the filter element be favored. The formation of the filter element with a such profile wave is expensive. Along one Edge or along both unfolded edges of the Filter element, the mold with a sealing web be trained in one of the last fold valleys of the zigzag-shaped filter element fits. This sealing web is intended to fold the detected fold of the Filter element against the closed mold to press the opposite mold half and thereby the To seal the mold.

DE-AS 23 01 635 describes a device and a Process for the production of a plate-shaped filter insert for the intake air of internal combustion engines. The filter insert consists of a zigzag fold and cuboidal filter fabric web, which is the actual  Filter element forms the one in a clamping flange having edging made of plastic is embedded. The device has a mold half Upper part and a forming a second mold half Lower part, with the inner profiles of the upper and the Lower part together with edge surfaces of the filter element Limit edge edging together with clamping flange. In the lower part the mold is a prefabricated filter element fixing and the lower part of the filter element of the Pouring cavity for the edging of the filter element separating web frame attached. The web frame shows in Direction of the outer surface of the filter element dimensions, which are smaller than the thickness dimension of the filter element. The prefabricated cuboid filter element is in the am The bottom part of the casting mold is inserted, after which after putting on the upper part of the mold Inner profile of the lower mold part limited cavity close to the upper edge of the frame with a liquid plastic Reaction mixture, especially a liquid Polyurethane mass is filled, which foams and the whole Fills the cavity of the mold, after which that Reaction mixture with the exposed edges of the Filter element and if necessary with edge flanges one hood-like wire mesh connects intimately, then to solidify. Through the trained in the mold Bridge frame does not just result in one too negligible manufacturing effort for the mold, but also the lack that the connection between the Plastic reaction mixture and the filter insert just over a partial surface of the outer surface of the filter insert extends. However, this leaves the dimensional stability of this known Filters wishes open. It is also in the process of doing this known method can not safely rule out that at improper foaming the plastic reaction mixture  while overflowing over the web frame is thin and therefore too strong in the porous filter material or between the possibly existing filter layers of the Filter penetrates and in this way the passage area is reduced through the filter. This can be a excessive flow resistance through the filter surrender.

DE-PS 33 31 524 C1 describes a plate-shaped Filter insert for the intake air for internal combustion engines, whereby the filter insert made of a zigzag folded There is a filter fabric and one to the filter fabric foamed edge for storing the filter insert in a the level of the filter insert divided housing is provided. In order to do an elaborate training of the mold - like her is given in the above-mentioned DE-AS 23 01 635 - to To avoid, it is suggested that the zigzag shape pleated filter foamed edge from a rigid inside Cross section of U-shaped frame, the U-shaped Frame of a shortened U- pointing towards the filter fabric Has thighs. This shortened U-leg serves as a replacement of the web frame according to DE-AS 23 01 635. Also in the Filter insert according to DE-PS 33 31 524 C1 result, however regarding the mechanically firm connection between the zig-zag zag-shaped folded filter element and the attached foamed peripheral edge, d. H. Framework, same flaws as in the training according to DE-AS 23 01 635. The same applies for the flow behavior or the flow resistance through  through the filter if the reaction mixture is too thin applied.

DE-OS 21 17 523 describes a method and a device known for making objects. According to the procedure there for making items with at least one Existing semi-finished wall, such as boxes, furniture, Window sash, housing, skylight domes or the like in one form, the cavity of which is the shape of the object to be manufactured corresponds, at least one wall element inserted in this way and in its position fixes that space for a frame remains free in which the at least one wall element projects with its edge, after which the cavity of the mold is foamed. To Carrying out this procedure becomes a device proposed that forms a closed form from a Outer wall and a core that is in the frame area between them limit the cavity for the plastic to be foamed, whose surfaces in the wall area are roughly parallel to the Wall elements are located and at least in the edge area of the Wall elements at a distance from the edges of the wall elements Apply to wall element surfaces.

DE-OS 19 16 330 discloses a system for the production of large or complex shaped molded parts from liquid multi-component plastics, consisting of a fixed mold filling machine, which is provided with a metering device, a mixing device and an ejection nozzle for the mixed plastics, and from in the mold filling machine insertable molds that are open during the filling process. There are working means for displacing the ejection nozzle relative to the opened mold to be filled during the ejection process according to a predetermined program, which is set up according to the geometry of the mold. With this system, a displacement movement is preferably possible in two coordinates, ie along an x axis and along a y axis.

A filter insert in plate form, which is particularly suitable for Air filter provided by internal combustion engines is from the DE-PS 36 42 135 C1 known. This filter insert also shows  a zigzag folded and essentially the shape of a flat block of filter cloth and one sealing the filter fabric strip on its four narrow sides enclosing molded elastic plastic frame. Between the plastic frame on the one hand and the two Narrow sides with the folded course of the Filter stripe, on the other hand, is the inside of each Fold the filter fabric strip against the plastic frame delimiting thin sealing material strips arranged, the Height about half to three quarters of the height of the adjacent Narrow side of the folded filter fabric strip is, and which in the lower part of the frame during the casting process Filter fabric strip is arranged. So here it is originally a relatively low viscosity plastic reaction mixture using a strip of sealing material to flow into the Filter material hindered. The connection with the filter material only occurs when the plastic reaction mixture becomes more viscous has become. A shortcoming of this known filter insert will be seen in that a separate sealing material strip for Must be made available and handled. The mechanical firm connection between the filter element and the However, plastic frame is only with this filter insert in the area next to or above the sealing material strip, what is considered another shortcoming.

The invention has for its object a method of type mentioned and a device for carrying out to create this method with which filter can be realized are that are inexpensive to manufacture and that are a good one Dimensional stability with good passage and filter behavior have.  

According to the method, this object is achieved in that the filter element folded in a zigzag shape with a Filter element corresponding to the shape of a zigzag first seal formed first mold half of the Casting mold is introduced, the filter element on the zigzag-shaped first seal is applied flat that on the first mold half then the one with the filter element corresponds in shape to zigzag second seal formed second mold half is arranged, the zigzag folded Filter element between the two corresponding to each other interlocking zigzag seals is clamped, and that subsequently in the cavity of the Poured the reaction mixture and then the Cavity is closed with a cover element. With help the two zigzag seals become the open ones zigzag-shaped edge sections of the filter element sealed, projecting over the seals Edge sections of the filter element folded in a zigzag shape stand in the cavity of the mold. This about the Seals in the cavity protruding edge portions of the The filter element then results in the mechanically firm connection between the zigzag folded filter element and the the frame surrounding the filter element. By closing the groove-shaped cavity formed in the casting device with the cover element, it is possible to foam the Plastic reaction mixture to limit precisely defined in this way the frame comprising the filter element manufacture without the need to frame deburr or rework in another way. The mechanically firm connection between the filter element and the Of course, the frame is not just along the open zigzag folded edge section of the filter element, but also along the two facing away from each other  Given edge portions of the filter element in the direction of Folding of the filter element are oriented.

The reaction mixture is introduced into the trough-shaped cavity of the casting mold, preferably by means of an xy coordinate device, before the cavity is closed off with the cover element. It is possible to use the xy coordinate device to move the casting mold, ie the channel-shaped cavity and / or the mixing head, relative to the casting mold, through which the plastic reaction mixture is introduced into the channel-shaped cavity of the casting mold. Immediately after the plastic reaction mixture has been introduced into the cavity, the channel-shaped cavity is sealed off with the cover element after the start of the reaction process, so that the foaming process of the plastic reaction mixture is limited in a precisely defined manner and a frame is thus formed which does not require any subsequent processing.

A polyurethane is preferably used as the reaction mixture Application. Of course it is also possible to offer others to use known reaction mixture materials.

The device for performing the method of manufacture a filter with at least one filter layer zigzag folded filter element and a Filter element surrounding frame, the device being a Casting mold with a first and a second mold half has and a seal for sealing the Limit filter element to the frame and around that Filter element surrounding surface section is provided, is characterized in that the first mold half with one of the filter elements folded in a zigzag shape corresponding zigzag-shaped first seal and the  second mold half with a zigzag shape folded filter element corresponding in shape to zigzag shaped second seal is formed, the two zigzag-shaped seals in the closed state of the Interlock the casting mold and the zigzag between them form-folded filter element sealing, and that the two mold halves to the side of the seals a circumferential shape corresponding to the frame form channel-shaped cavity, which is used to introduce a Plastic reaction mixture provided for the frame and with a cover element can be closed. Such a device is simple and has the particular advantage that it is easily possible with her, a zigzag shape to produce pleated filter element with a frame that with the filter element along the entire circumference of the Filter element is mechanically securely connected, the further gives good dimensional stability of the filter. The Filters can be z. B. as a pure dust or particle filter be designed so that as a material for the filter element for example paper, electret fleece or a glass fiber fleece can be used. Another option is in the folding, d. H. Pleated from at least one layer from a material having adsorption properties existing filter element. Furthermore, it is possible to fold several layers together, d. H. to pleat on this way a combination of particle and adsorber filters to realize. Coming as material for an adsorber filter for example, coated with activated carbon balls or grains and / or impregnated with a powder of activated carbon or printed nonwovens or the like. The Activated carbon particles can be coated or by others suitable materials must be replaced.

The two zigzag seals of the two  Casting mold halves of the casting mold can, as it were, block-like extend over the pleat length of the pleated filter element. The first and second zigzag seals face in Folding direction of the filter element preferably dimensions, which are shorter than the corresponding dimension of the Filter element in the direction of folding so that the filter element with Edge sections of its two folded end faces over the Seals protrudes and with the edge sections in the the seals protrude adjacent cavity. Along this edge portions protruding into the cavity then a connection between the filter element and that Filter element bordering frame.

Instead of the two seals along the length of the folded edges extends, it is possible that the first and the second zigzag seal in the neighborhood of the two facing end faces of the Filter element as a strip-like toothed structure are formed with each other by in the direction of folding extending strip-shaped sealing members are connected, the in the neighborhood of the two facing away from each other unfolded edges of the filter element are provided, wherein the unfolded edges of the filter element with edge sections stand in the cavity of the mold. Depending on the Dimensions of the filter have the strip-shaped toothed Formations and the strip-shaped in the direction of folding Sealing elements, for example, width dimensions in the area between approx. 5 and 20 mm. Such a width is regularly for a reliable internal seal, d. H. For a seal of the folded edge sections between the Seals of trapped filter elements, sufficient.

An xy coordinate device is preferably provided for introducing the reaction mixture into the trough-shaped cavity of the casting mold with the cover element removed from the casting mold. With such an xy coordinate device, it is easily possible to introduce the plastic reaction mixture virtually without pressure into the cavity of the casting mold corresponding to the frame. With the help of the xy coordinate device, it is possible to move either the casting mold with a fixed casting head or the casting head with a fixed casting mold in accordance with the course of the channel-shaped cavity. Of course, it is also possible to move both the casting mold and the mixing head, through which the plastic reaction mixture is introduced into the channel-shaped cavity of the casting mold. Regardless of the movement of the casting mold and / or the casting head, there is a uniform, time-saving introduction of the plastic reaction mixture into the cavity. Immediately after the foaming plastic reaction mixture has been introduced, the channel-shaped cavity - as already stated - is closed with the cover element, as a result of which the foaming of the reaction mixture is limited in a defined manner.

It has proven to be useful if the first Half of the mold a seal belonging to it has side wall facing away to delimit the cavity, to form a clamping groove in the frame with an approach is formed. The approach preferably runs around closed around the cavity of the first mold. On this results in an outside of the frame circumferential clamping groove. With the help of the clamping groove, the filter in a device provided for this purpose is clamped tightly or be held.

The invention is explained in more detail using the Description of one in the drawing  schematically sectionally drawn device for Implementation of the process for producing a filter as well of a filter drawn in sections, which in this Device has been manufactured. It shows

Fig. 1 is a view of a portion of the apparatus from above,

Fig. 2 shows a section through the device along the section line II-II in Fig. 1

Fig. 3 shows a section through a portion of the filter in one of the Fig. 2 view corresponding direction and

Fig. 4 shows a section along the section line IV-IV in Fig. 3.

Figs. 1 and 2 show in a plan view and a sectional view of a portion of a mold 10 comprising a first mold half 12 and a second mold half 14 and a cover member 16. The first mold half 12 has a base part 18 , from which a side wall 20 protrudes. A first seal 22, 24 projects from the base part 18 in the same direction as the side wall 20 , the seal 22 consisting of two zigzag-shaped strip elements, only one of which can be seen in sections in FIG. 1. Likewise, only a strip-shaped seal 24 can be seen in sections from FIG. 1, which extends in the folding direction, while the zigzag-shaped strip-shaped seal 22 is oriented at least approximately perpendicular to the folding direction.

The second mold half 14 has a plate-shaped closure part 26 , from which a second seal 28, 30 protrudes in the same direction. The second seal 28 consists of two spaced zigzag-shaped strip-shaped elements, one of which is indicated in sections in FIG. 1. Likewise, the seals 30 consist of strip-shaped sealing elements, of which only one is also drawn in sections in FIG. 1. The zigzag-shaped second seals 28 and the first zigzag-shaped seals 22 engage in the closed state of the casting mold 10 shown in FIG. 2 and clamp between them the zigzag-shaped, at least single-layered filter element 32 sealing one. At the same time, the folded filter element 32 is clamped between the strip-shaped seals 24 and 30 , edge sections 34 and edge sections 36 of the filter element 32 projecting via the seals 22, 28 and 24, 30 into a cavity 38 which is between the side wall 20 and the seals 22, 28 or 24, 30 and the base 18 of the first mold half 12 is provided in a channel shape. The circumferential side wall 20 is formed with a circumferential shoulder 40 and with a circumferential groove 42 adjacent to the shoulder 40 , the shoulder 40 in the filter 44 having a clamping groove 46 and the groove 42 in the side wall 20 of the first mold half 12 in the filter 44 a circumferential collar 48 results, as can be seen from FIGS. 3 and 4. The last-mentioned figures also show the frame 50 which extends around the filter element 32 and whose cross-sectional profile corresponds to the cross-sectional profile of the cavity 38 (see FIG. 2). . 3 and 4 of Figs, the mechanically fixed connection between the filter element 32 and the frame 50 along the edge portions 34 (see Fig. 4) and 36 (see Fig. 3) can be clearly seen. In particular, from Fig. 4 it can be seen that the two folded end sides of the filter element 32 are connected mechanically firmly and sealingly along its entire length with the frame 50.

In FIG. 2, the mold is shown with the lid member 16 10, wherein the lid member 16 closes the cavity 38 sealingly. Before the cover element 16 is arranged on the cavity 38 , a plastic reaction mixture is introduced into the cavity with the aid of an xy coordinate device 52 and / or by means of an xy coordinate device 54 , which is distributed uniformly in FIG. 2 by a casting head 56 outgoing arrow 58 directed into the cavity 38 is indicated. This is to mean that the casting head 56 and / or the casting mold 10 can be moved with the xy coordinate device 52 and / or by means of the xy coordinate device 54 in order to introduce the plastic reaction mixture evenly distributed into the channel-shaped cavity 38 surrounding the filter element 32 . After the plastic reaction mixture has been introduced, the trough-shaped cavity 38 is closed with the cover element 16 , so that the reaction mixture can only foam in a defined manner in order to form the frame 50 which runs around the filter element 32 (see FIGS. 3 and 4).

Due to the uniform distribution of the plastic reaction mixture along the circumferential channel-shaped cavity 38 and the relatively slow expansion behavior of the special foam material used, only a comparatively low pressure is exerted on the seals of the casting mold. A special inner seal with respect to the filter material, ie with respect to the folded filter element 32, is therefore not necessary.

Claims (9)

1. A method for producing a filter ( 44 ) with a zigzag-folded filter element ( 32 ) having at least one filter layer and a frame ( 50 ) surrounding the filter element ( 32 ), the filter element ( 32 ) being placed in a first mold half ( 12 ) a casting mold ( 10 ) having two casting mold halves ( 12, 14 ) is introduced, which delimits the filter element ( 32 ) towards the frame ( 50 ) and extends around the filter element ( 32 ) between the first and the second casting mold halves ( 12, 14 ) is sealed by means of a seal ( 22, 28; 24, 30 ), and a foaming plastic reaction mixture is introduced into the cavity ( 38 ) defined by the seal in the mold halves ( 12, 14 ), which after the course of the reaction has the the filter element ( 32 ) forms a fixed frame ( 50 ), characterized in that the zigzag-shaped folded filter element ( 32 ) into one with the filter element ( 32 ) form-fitting first zigzag-shaped first seal ( 22 ), first mold half ( 12 ) of the mold ( 10 ) is introduced, the filter element ( 32 ) being applied flat to the zigzag-shaped first seal ( 22 ) that the second casting mold half ( 14 ), which is designed with a zigzag-shaped second seal ( 28 ) corresponding in shape to the filter element ( 32 ), is then arranged on the first casting mold half ( 12 ), the zigzag-shaped filter element ( 32 ) between the two corresponding interlocking zigzag seals ( 22, 28 ) is tightly clamped, and that subsequently the reaction mixture is introduced into the cavity ( 38 ) of the casting mold ( 10 ) and then the cavity ( 38 ) with a cover element ( 16 ) is closed. 2. The method according to claim 1, characterized in that the reaction mixture in the cavity ( 38 ) of the casting mold ( 10 ) by means of an xy coordinate device ( 52, 54 ) is introduced before the trough-shaped cavity ( 38 ) with the cover element ( 16 ) is completed becomes. 3. The method according to claim 1 or 2, characterized, that a polyurethane is used as the reaction mixture. 4. Device for carrying out the method according to one of the preceding claims for producing a filter ( 44 ) with a at least one filter layer having a zigzag-shaped filter element ( 32 ) and a surrounding the filter element ( 32 ) frame ( 50 ), the Device has a casting mold ( 10 ) with a first and a second casting mold half ( 12, 14 ) and a seal ( 22, 28; 24, 30 ) for sealing a filter element ( 32 ) delimiting the frame ( 50 ) and around the filter element ( 32 ) circumferential surface section is provided, characterized in that the first mold half ( 12 ) with a zigzag-shaped filter element ( 32 ) in shape corresponding to the zigzag first seal ( 22 ) and the second mold half ( 14 ) is formed with a zigzag-shaped filter element ( 32 ) corresponding to the shape of a zigzag-shaped second seal ( 28 ), wobe i the two zigzag seals ( 22, 28 ) engage in the closed state of the casting mold ( 10 ) and fix the zigzag folded filter element ( 32 ) between them in a sealing manner and that the two casting mold halves ( 12, 14 ) laterally next to the seals ( 22, 28; 24, 30 ) form a circumferential channel-shaped cavity ( 38 ) corresponding to the shape of the frame ( 50 ), which is provided for introducing a plastic reaction mixture for the frame ( 50 ) and can be closed with a cover element ( 16 ). 5. The device according to claim 4, characterized in that the first and the second zigzag-shaped seal ( 22, 28 ) in the folding direction of the filter element ( 32 ) have dimensions that are shorter than the corresponding dimension of the filter element ( 32 ) in Folding direction, so that the filter element ( 32 ) with edge sections ( 34 ) of its two folded end faces protrudes beyond the seals ( 22, 28 ) and projects with the edge sections ( 34 ) into the cavity ( 38 ) adjacent to the seals ( 22, 28 ) . 6. The device according to claim 4, characterized in that the first and the second zigzag-shaped seal ( 22, 28 ) in the vicinity of the two facing end faces of the filter element ( 32 ) as a strip-shaped toothed structure ( 22, 28 ) are formed, which are connected to one another by strip-shaped sealing members ( 24, 30 ) running in the direction of folding, which are provided in the vicinity of the two unfolded edges of the filter element ( 32 ) facing away from one another, the unfolded edges of the filter element ( 32 ) having edge sections ( 36 ) protrude into the cavity ( 38 ) of the casting mold ( 10 ). 7. Device according to one of claims 4 to 6, characterized in that an xy coordinate device ( 52, 54 ) is provided for introducing the plastic reaction mixture into the trough-shaped circumferential cavity ( 38 ) of the casting mold ( 10 ). 8. Device according to one of claims 4 to 7, characterized in that the first mold half ( 12 ) has a side wall ( 20 ) facing away from its associated seal ( 22, 24 ) for delimiting the channel-shaped cavity ( 38 ) which forms a Clamping groove ( 46 ) is formed in the frame ( 50 ) with an extension ( 40 ). 9. The device according to claim 8, characterized in that the projection ( 40 ) around the cavity ( 38 ) of the first mold half ( 12 ) rotates.