DE102004022776A1 - Sieve changing apparatus for use in purifying polymer melts produced by extruders comprises strip with apertures, into which filters fit strip being mounted in housing fastened together by flange, through which flow channel for melt passes - Google Patents

Abstract

Sieve changing apparatus for use in purifying polymer melts produced by extruders comprises a strip (3) with apertures (4), into which filters (9) fit. The strip is mounted in a housing (2) which is fastened together by flanges (7, 8), through which a flow channel (14) for the melt passes. A drive system (6) allows strip to be raised and lowered and it has a bore in one sides for a locking pin (12). An independent claim is included for a method for changing sieves by inserting a strip into the casing, heating it, raising it so that a sieve coincides with the melt channel and locking it in position.

Description

Territory of invention

The The present invention relates to a screen changer for cleaning of polymer melts.

The Purification of polymer melts from extruders or other plastic processing Machines are a commonly practiced technique.

It Various agents are used, the foreign body in the Passing the polymer melt in a device hold back. These funds can For example, perforated sheets in the form of sieves or metal mesh be different, especially narrow mesh sizes.

At the Flow through this agent will clean the polymer material.

ever after occupancy of the agents used for the purification of the polymer melt it is necessary to change these while keeping the stream of molten Polymer as possible little to influence the production of the plastic made Do not interrupt the article. This is in particular a pressure increase To avoid the melt, which is a hindrance in production.

Out In the prior art are devices for changing screens are used, known.

The DE 33 02 343 C2 describes a rotary driven filter disc which projects into the melt channel, is equipped with sieve elements, and allows a change of the sieves, wherein the disc is further rotated.

In the DE 42 35 523 C1 is a screen changer with a rotary-driven filter disc, are supported in the sieves, disclosed, wherein the melt stream forks in the direction of the filter disc and this offers two part of the mouths at the pitch of the openings of the filter disc.

In the DE 42 12 928 A1 It is proposed that a rocker can be pivoted into or out of the melt channel carrying the screening elements.

The font DE 44 19 284 C1 focuses on sealing elements which seal a slide or a rocker for receiving the screens against the melt channel.

The aforementioned solutions have a number of disadvantages.

These consist in that the sieves, after getting out of the melt stream were moved out, for replacement of the device for melt filtration can be seen.

These Work is carried out directly on the machine and are generally technically complex, since on the one hand the sieves through the high pressures the one flowing through them Plastic melts firmly in the holders provided are pressed.

Farther limited the accessibility and prevailing heat the cleaning options on the extrusion machine.

task The present invention is therefore, the disadvantages mentioned by a novel device for easy and quick Sievesaustausch to overcome.

description

Here uses the invention, which has set itself the goal of a To create a device that knows the disadvantages mentioned the state of the art over winds and a simplification of the sieve replacement under production conditions time optimized.

The Task is solved according to claim 1.

preferred versions and further developments can be found in the subclaims.

One Method for changing the screen is proposed in claim 18 according to the invention, Use of the screen changing device according to claim 17.

According to the invention was Recognized that replacing a soiled screen in a simple and easy way time-optimized manner can take place when the sieve containing Sieve strip, after it has been moved out of the melt stream, is removed and so after cooling for cleaning, replacement and service work available stands.

The features of the invention are explained in detail with reference to the description of embodiments in conjunction with these illustrative drawings, this being not restrictive is to be understood.

embodiment

It show here:

1 the screen changer in an overall view;

2 the screen housing with Siebleisten therein;

3 a sill with T-shaped fasteners, sieve and filter cartridge, and the series arrangement of interconnected Siebleisten;

4a a section through sieve housing and Siebleisten, wherein the sieve is positioned in operative position, in 4b in change position with respect to the melt guide.

in this connection represent

1

Screen Changer

2

screen housing

3

A drainage foil

4

Breakthrough in the sieve strip ( 3 )

5

Area that the breakthrough ( 4 ) limited

6

driving element

7

Fastening means, designed as a flange

8th

Fastening means, designed as a flange

9

scree

10

filter cartridge

11

heating element

12

Locking element for positioning and locking the sieve strip ( 3 )

13

Recess in the sieve strip ( 3 ) into which the locking element ( 12 ) intervenes

14

Melt lead.

In 1 is a screen changer ( 1 ) according to a first embodiment of the invention as it comes in the purification of polymer materials used.

The screen changer ( 1 ) is arranged between extruder and extrusion tool or a melt pump and with fastening means ( 7 . 8th ) in the form of screw flanges on the extruder and attached to the extrusion die.

The screen changer ( 1 ) has a screen housing ( 2 ), which forms a channel perpendicular to the melt stream and in which the Siebleisten ( 3 ) are arranged.

The Siebelisten ( 3 ) are connected to each other releasably positive and positive. You have one or more breakthroughs ( 4 ), which are designed so that sieves ( 9 ) with or without filter cartridges ( 10 ) in the breakthroughs ( 4 ) are arranged and held.

The breakthrough ( 4 ) has a round or an oval or a curved or an angular shape, it can also be formed a hybrid form, which is derived from the aforementioned forms. The breakthrough ( 4 ) is separated from a surface ( 5 ) limited.

The sieves ( 9 ) are made of metal or of ceramic or of polymer material or of a mixed composition of the aforementioned materials.

By means of a drive element ( 6 ) are the Siebleisten ( 3 ) in the channel of the screen housing ( 2 ) linearly movable and can be introduced into a defined position, in which a breakthrough ( 4 ) Centric to the melt guide ( 14 ), whereby the polymer melt is purified by the sieve ( 9 ) flows through.

The defined position of the sieve strip ( 3 ) is by means of a locking element ( 12 ), for example in the form of a locking bolt, which is in a peripheral recess ( 13 ) in the sieve strip ( 3 ) intervenes. The recess ( 13 ) is on the side of the sieve ( 3 ) attached to the edge. The sieve strip ( 3 ) is thus in the engaged position of the locking element ( 12 ) Centric to the melt guide ( 14 ) and secured against displacement.

The breakthrough ( 4 ) the sieve strip ( 3 ) delimiting areas ( 5 ) act together with surfaces of the screen housing ( 2 ) sealing against the polymer melt in the melt guide ( 14 ), because they are brought into sealing contact with each other.

The screen housing ( 2 ) has heating elements ( 11 ) on.

It is advantageous that the screen changer according to the invention ( 1 ) made of simple components and is inexpensive to produce. The screen changing device ( 1 ) is made of steel.

In 2 is a screen housing ( 2 ) in which you can see 3 ) are arranged, wherein the fastening means ( 7 . 8th ) are not shown in the form of the flanges.

The 2 shows the detachable non-positive and positive-connected wire-length lists ( 3 ) in a series arrangement in the housing ( 2 ) of the screen changing device ( 1 ), the locking element ( 12 ) and the recess ( 13 ) on the sieve strip ( 3 ).

The screen housing ( 2 ) has heating elements ( 11 ), which serve the sieve housing ( 2 ) and the seal lists ( 3 ) so that the polymer melt stream is not inhibited.

In 3a is the structure of a single sieve strip ( 3 ).

The Siebelisten ( 3 ) Breakthroughs ( 4 ), wherein in each sieve ( 3 ) two round breakthroughs ( 4 ) are shown as a preferred embodiment of the invention. In these breakthroughs ( 4 ) sieves ( 9 ) are arranged and held, which clean the polymer melt flowing through them.

It is also possible to use filter cartridges ( 10 ) as a metal fabric execution in addition to the sieves ( 9 ) in the breakthroughs ( 4 ) to obtain a higher cleaning effect. Such filter cartridges ( 10 ) may, for example, be in the form of close-meshed metal fabrics.

Furthermore, in 3b The releasable non-positive and positive connection of Siebleisten ( 3 ) in the form of a series arrangement. By way of example, T-shaped connecting elements are shown.

But there are also differently shaped fasteners possible, such as those in dovetail shape, which are not shown in detail. In addition, other arbitrarily designed fasteners that a releasable non-positive and positive connection of Siebleisten ( 3 ) allow for series arrangements, can be used.

The Siebelisten ( 3 ) have recesses ( 13 ) at the edges on opposite sides, which for positioning by means of the locking element, not shown here ( 12 ), which is formed in the form of a locking bolt can be used.

4a represents in a cross section the active position of a sieve ( 9 ) of the screen changer ( 1 ).

In active position is the sieve ( 9 ) Centric to the melt guide ( 14 ).

4b shows a cross section through the screen changer ( 1 ), whereby the change of position of a sieve ( 9 ) is shown.

Here is the sieve ( 9 ) not centric to the melt guide ( 14 ), it protrudes into this only with a partial surface.

In the 4a , b is the screen housing ( 2 ) with therein record lists ( 3 ), the sieves ( 9 ) or close-meshed metal mesh. On the side are fasteners ( 7 . 8th ) in the form of flanges.

The positive association of the seal lists ( 3 ) is shown in the form of a series arrangement.

The heating elements ( 11 ) for heating the screen changer ( 1 ) and the Siebleisten ( 3 ) with the seven ( 9 ) and the locking element ( 12 ) are shown.

In the screen housing ( 2 ) of the screen changer ( 1 ) is introduced a channel perpendicular to the direction of the polymer melt stream, which has a substantially rectangular cross-section, wherein in 4a , b in each case a section through this channel is shown.

In this channel you will find listings ( 3 ) linearly displaceable, thereby individual Siebleisten ( 3 ) or series of interconnected Siebleisten ( 3 . 3 '' . 3 ''' ).

The channel in the housing ( 2 ) is dimensioned such that it seals in the spatial directions of the polymer melt flow with the corresponding surfaces of the sieve strip (FIG. 3 ) and thereby prevents the melt outlet. The sizing of the channel is chosen so that the sieve ( 3 ) by means of the drive element ( 6 ) is linearly movable in the channel. For this serve edge surfaces of the sieve strip ( 3 ), in which the recesses ( 13 ) are introduced, for guiding the linear movement of the perforated strip ( 3 ) in the screen housing ( 2 ).

In a further embodiment of the invention can also be provided that a plurality of parallel arranged in-line screen changer ( 1 ) are used to increase the cleaning performance.

In this case, advantageously, a cascade-like arrangement of ascending narrowing sieves ( 9 ) or filter cartridges ( 10 ) are selected from metal mesh narrowing mesh size in the direction of the polymer material flow, which have a particularly high cleaning efficiency.

It is also possible to provide an arrangement in which the polymer melt stream is divided and screen changers arranged side by side (FIG. 1 ) of the type according to the invention are flowed through, wherein a higher throughput of material is achieved.

In another embodiment of the invention, the screen changer ( 1 ) be designed so that both cascaded cascaded sieves ( 9 ), which become increasingly narrower, as well as a parallel arrangement of such a plurality of sieves ( 9 ) to purify the polymer material stream.

The cleaning performance of the sieves ( 9 ) and filter cartridges ( 10 ) depends on the size of the openings in the sieves ( 9 ) and the mesh sizes of the metal mesh containing the filter cartridges ( 10 ) form, given. For very narrow openings and very narrow mesh sizes, a high cleaning performance is achieved, whereby the throughput of polymer material is limited. Higher throughputs of polymer material can be achieved with coarser sieves ( 9 ) and filter cartridges ( 10 ) achieve smaller mesh size.

The screen change and the replacement of the sieves ( 9 ) is in the screen changer according to the invention ( 1 ) in the following process steps:
Initially, a first sieve strip ( 3 ) in the screen changing device ( 1 ) brought in.

The sieve strip ( 3 ) is calculated according to the number of breakthroughs ( 4 ) with sieves ( 9 ) and optionally with filter cartridges ( 10 ) in the form of, for example, closely meshed metal mesh.

In the screen housing ( 2 ) are in openings close to the melt guide ( 14 ), heating elements ( 11 ), which the screen housing ( 2 ) bring to operating temperature and thus allow the undisturbed flow of polymer melt.

It is beneficial if the cleaned and with sieves ( 9 ) equipped Siebelisten ( 3 ) before introduction into the active position in the screen changer ( 1 ) are heated to operating temperature.

The heating of the Siebleisten ( 3 ) to operating temperature, ie preferably to the temperature at which the polymer melt leaves the extruder, is thereby preferably achieved by the sieve strip ( 3 ) with the sieve ( 9 ) before introduction into the melt guide ( 14 ) first for some time in the heated screen housing ( 2 ) remains until a temperature equilibrium has been established.

This so equipped first sieve strip ( 3 ) after heating to operating temperature by means of the drive element ( 6 ) moved linearly such that the sieve ( 9 ) Centric to the melt guide ( 14 ) and thereby the locking element ( 12 ) in the edge-side recess ( 13 ) the sieve strip ( 3 ) and so the positioning of the sill ( 3 ) in operative position and this secures against shifting.

In the operative position of the sieve ( 9 ), the purification of the polymer melt takes place. This flows through the sieve ( 9 ), whereby contaminants are retained and the polymer melt is cleaned. The sieve ( 9 ) is thereby occupied over time, so that a screen change is necessary.

When the sieve ( 9 ) is coated with contaminants from the polymer material, a screen change is to be made such that a second screen ( 3 '' ) with a sieve ( 9 ), into the screen housing ( 2 ) is introduced and at the first Siebleiste ( 3 ) is coupled by means of the connecting elements.

After a temperature equilibrium has been reached, the drive element ( 6 ) the linked series of listings ( 3 . 3 '' ) shifted linearly so far that the second sieve strip ( 3 ' ) with the supported sieve ( 9 ) comes into operative position.

The sieve ( 9 ), which is in the sieve 3 ) is arranged, is thereby from the drive element ( 6 ) from a position outside the melt guide ( 14 ) is above a change position, where the sieve ( 9 ) with a proportion of its surface in the polymer melt stream is moved to the active position. In the operative position stands the sieve ( 9 ) Centric to the melt guide ( 14 ) and cleans the polymer melt flowing through it.

The sieve strip ( 3 ) is constructed so that in the change position of the sieve ( 3 ) The polymer material flow is impeded as little as possible, so that the production of the article made of the plastic material is not interrupted and a pressure increase of the melt is avoided.

In particular, the seal lists ( 3 ) are connected to one another in such a way that a form-fitting arrangement of rows is present, which at the connection points of the individual seal strips ( 3 ) in turn is tight against the pressure of the polymer melt and thus prevents penetration of polymer material.

When using a sieve strip ( 3 ) with several breakthroughs ( 4 ), it must always be shifted linearly when changing the screen so that the following breakthrough ( 4 ) with the sieve ( 9 ) in operative position to the melt guide ( 14 ) is brought.

To move is first the locking element ( 12 ), so that the first sieve strip ( 3 ) by means of the drive element ( 6 ) can be moved.

After moving the Siebelisten ( 3 . 3 ' ) connected in series turn the locking element ( 12 ) and the sieve strip ( 3 ) locked by.

Through a corresponding linear movement of the Siebelisten ( 3 . 3 ' ), the first sieve strip ( 3 ) from the screen housing ( 2 ) and can be decoupled.

After uncoupling the strainer ( 3 ) is immediately available for cleaning.

This Procedure is repeated for changing the sieve.

The drive element ( 6 ), which controls the movement of the sieve 3 ) effected perpendicular to the melt stream can act mechanically or electromechanically or hydraulically or pneumatically.

The sieve strip ( 3 ) with the soiled sieve ( 9 ) coming out of the screen housing ( 2 ) has moved out of the series arrangement of interconnected Siebleisten ( 3 ) and is after cooling for disassembly and cleaning or replacement of the components, in particular of the sieve ( 9 ), ready. This has an advantageous effect that the cleaning and replacement activities on cooled Siebleisten ( 3 ) are vornehmbar, which facilitates the work to be done and also protects the components.

Particularly advantageous is the fact that those with sieves ( 9 ) equipped Siebelisten ( 3 ) can be kept in any number and so a screen change can be performed quickly, even in frequent succession and without interrupting the production or the polymer melt stream.

The following embodiment illustrates the advantage of the screen changer according to the invention ( 1 ):
A screen changer according to the invention ( 1 ) is used in the extrusion of polypropylene on a single screw extruder. Here, at a temperature of up to 250 ° C 60 to 90 kg of polymer material per hour at a pressure of up to 30 bar discharged. To make a screen change, a coupling takes place with a sieve ( 9 ) equipped sieve strip ( 3 ), which is then moved into operative position after temperature adjustment.

• -a- Bestücken einer zweiten Siebleiste (3) mit einem Sieb (9)
• -b- Einbringen der zweiten Siebleiste (3) in das Siebgehäuse (2)
• -c- Verbinden der zweiten Siebleiste (3) mit der im Siebgehäuse (2) befindlichen ersten Siebleiste (3)
• -d- Erwärmen der zweiten Siebleiste (3) auf Betriebstemperatur
• -e- Entriegelung der in Wirkstellung befindlichen ersten Siebleiste (3)
• -f- Bewegen der zweiten Siebleiste (3) mittels des Antriebselements (6) in Wirkstellung, wobei das Sieb (9) in Wirkstellung zum Schmelzekanal (14) kommt
• -g- Verriegelung der in Wirkstellung angeordneten zweiten Siebleiste (3) mit dem Verriegelungselement (12)
• -h- Entnahme der aus der Wirkstellung herausbewegten ersten Siebleiste (3).

The decoupling of a sieve strip ( 3 ) with a dirty sieve ( 9 ) is easily possible. This only takes about one third (less than 1 min) of the time required to replace a sieve ( 9 ) is necessary according to the known state of the art, this being true at the screen changing device ( 1 ) is to be done directly on the machine.

• -a- Equipping a second sieve strip ( 3 ) with a sieve ( 9 )
• -b- Inserting the second sieve strip ( 3 ) in the screen housing ( 2 )
• -c- connecting the second sieve strip ( 3 ) with the in the screen housing ( 2 ) located first Siebleiste ( 3 )
• -d- heating the second sieve strip ( 3 ) to operating temperature
• -e- unlocking of the first sieve strip ( 3 )
• -f- move the second sill ( 3 ) by means of the drive element ( 6 ) in operative position, wherein the sieve ( 9 ) in operative position to the melt channel ( 14 ) comes
• -g- locking of the second sieve strip arranged in operative position ( 3 ) with the locking element ( 12 )
• -h- removal of the moved out of the operative position first perforated strip ( 3 ).

Claims (19)

Screen changing device ( 1 ) for the purification of polymer melts released, in particular by extruders, comprising a device in which a melt guide (in 14 ) having Siebgehäuse ( 2 ) a sieve ( 9 ), characterized in that -a- a sieve strip ( 3 ) with a breakthrough ( 4 ) for receiving and holding a screen ( 9 ), where -b- is the list of 3 ) releasably connected in a series arrangement with positive and non-positive locking and -c- the sealing strips ( 3 ) in a sieve housing ( 2 ), wherein -d- is the sieve strip ( 3 ) the break through ( 4 ) delimiting areas ( 5 ), which together with surfaces of the screen housing ( 2 ) are brought into abutment and seal, wherein -e- the sieve housing ( 2 ) Fastening means ( 7 . 8th ) and -f- a drive element ( 6 ) the sieve strip ( 3 ) through the screen housing ( 2 ), where -g- a recess ( 13 ) in the sieve strip ( 3 ) is mounted so that a locking element ( 12 ) and -h- a positioning of the screen ( 9 ) Centric to the melt guide ( 14 ) is achieved. Screen changing device ( 1 ) according to claim 1, characterized in that the sieve strip ( 3 ) over several breakthroughs ( 4 ), preferably two breakthroughs ( 4 ), which the sieves ( 9 ) and / or the filter cartridges ( 10 ) take up. Screen changing device ( 1 ) according to claim 2, characterized in that the breakthrough ( 4 ) in the sieve strip ( 3 ) has a round or oval or curved or angular shape or a mixed form formed from the aforementioned forms. Screen changing device ( 1 ) according to claim 1, characterized in that the Siebleisten ( 3 ) are connected at the edge by T-shaped connecting elements. Screen changing device ( 1 ) according to claim 1, characterized in that the Siebleisten ( 3 ) are connected at the edge by dovetail-shaped connecting elements. Screen changing device ( 1 ) according to one of claims 1 to 5, characterized in that the drive element ( 6 ) the movement of the seal lists ( 3 ) effected mechanically or electromechanically or hydraulically or pneumatically. Screen changing device ( 1 ) according to one of the preceding claims, characterized in that the fastening means ( 7 . 8th ) are formed flange-shaped. Screen changing device ( 1 ) according to one of claims 1 to 7, characterized in that in the screen housing ( 2 ) of the screen changing device ( 1 ) in openings heating elements ( 11 ) are introduced. Screen changing device ( 1 ) according to one of claims 1 to 8, characterized in that the sieve strip ( 3 ) by a locking device, consisting of a locking element ( 12 ) and an edge-mounted recess ( 13 ) in the sieve strip ( 3 ), brought to positioning and locking in the operating position. Screen changing device ( 1 ) according to one of claims 1 to 9, characterized in that the sieve ( 9 ) consists of a metal or a ceramic or of a polymer material. Screen changing device ( 1 ) according to claim 10, characterized in that the sieve ( 9 ) consists of a mixed composition. Screen changing device ( 1 ) according to one of claims 1 to 11, characterized in that a plurality of sieves ( 9 ) and / or filter cartridges ( 10 ) are provided in a cascade-shaped arrangement. Screen changing device ( 1 ) according to one of claims 10 to 12, characterized in that the screen hole diameter decreases in the cascaded arrangement in the direction of the melt stream. Screen changing device ( 1 ) according to claims 1 to 9, characterized in that a parallel arrangement of at least two sieves ( 9 ) is provided. Screen changing device ( 1 ) according to claim 14, characterized in that the polymer melt stream is divided and the sieves arranged in parallel ( 9 ). Screen changing device ( 1 ) according to claim 1 to 15, characterized in that an arrangement of cascading behind one another attached sieves ( 9 ), which are additionally arranged in parallel, is provided. Use of a screen changing device ( 1 ) according to claim 1 to 16, in particular for the purification of discharged from extruders polymer melts. Method for changing the sieve with a sieve changing device ( 1 ) according to claims 1 to 16, characterized by the following method steps for the initial introduction of a first sieve strip ( 3 ) in the screen changing device ( 1 ): -a- loading a first sieve strip ( 3 ) with a sieve ( 9 ) -b- Inserting the first sieve strip ( 3 ) in the screen housing ( 2 ) -c heating the first sieve strip ( 3 ) to operating temperature -d- moving the first sieve strip ( 3 ) by means of the drive element ( 6 ) until the sieve ( 9 ) comes into operative position to the melt channel -e- locking the in effect position of the sieve ( 9 ) positioned first sieve strip ( 3 ) with the locking element ( 12 ), which in the edge-side recess ( 13 ) the sieve strip ( 3 ) intervenes. Method for changing the sieve with a sieve changing device ( 1 ) according to claim 18, characterized by the following method steps for exchanging a first screen strip located in the operating position ( 3 ):