RU2581371C1 - Device for filtration of molten plastic - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polymer industry. Technical result is achieved byfiltration device of plastic melt containing casing with inlet, outlet and inner drain channels on outer surface of which there are heating elements mounted in body filter unit connected with housing channels, drain cylinder, having on external surface of support elements, besides, on one side of cylinder has smooth surface, replaceable filtering element representing woven steel screen, tightened around bearing grate which is perforated steel sheet rolled in cylindrical shell. At that, body is through cylinder, inside which there is network of channels fouled and clean redistribution of molten plastic mass. Filtering unit represents cartridge consisting of replaceable filter element, bearing grate, drain cylinder, head and end piston of cartridge. Drain cylinder is connected with end piston cassette on one side and head of cartridge on other. Sealing elements consisting of circular gasket and pressure discs with thread, are fixed on end of cartridge and piston head holder. Cartridge head is steel cylinder composed of two successive paired pistons. At that, in piston body adjacent to drain cylinder, through holes are made in circle. At that, all cartridge elements apart from replaceable filter and sealing elements are assembled into single one-piece unit. Low-pressure chamber is located in space, limited by head and housing inner surface. End cartridge piston represents metal disc made so that cartridge has possibility to be repeatedly removed and inserted into body while providing tightness of filter. At that, cassette is taken out so that head of cassette does not leave limits of body.

EFFECT: technical result is increased efficiency, reliability and efficiency.

4 cl, 2 dwg

Description

The technical field to which the invention relates.

The invention relates to the polymer industry, and in particular to technological equipment for the manufacture of plastic products.

State of the art

A device for filtering the melt of polymeric materials (patent of the Russian Federation No. 2523808, publ. 07.27.2014) containing a housing, interchangeable cartridges.

The replaceable cartridge is a single cylindrical non-separable block, on the surface of which a filter element (mesh) is fixed. The cartridge consists of a drainage cylinder, a support grid, a cartridge head and a threaded cartridge flange. The molten plastic mass, having passed through a replaceable filter element and a support grid, enters a drainage cylinder equipped with a network of channels. Further, the melt moves through the cartridge head and enters the low-pressure chamber (purified melt), limited by the cartridge head and the housing end flange.

This patent describes two possible schemes for the movement of the polymer melt and the yield of purified material. In one embodiment, the output is through the end flange of the housing, and in another hole is located in the side surface of the housing itself, and the flange remains deaf. In both versions, the housing is a hollow cylinder equipped with a network of internal channels for supplying a dirty product, which serves to contain internal pressure. According to the design, the housing accepts both a radial tensile force and an axial force transmitted through the end flange of the cartridge on one side and the end flange of the body on the other.

Rigidly fixed blind end elements designed to contain internal pressure do not allow the cassette to move freely along the axis of the casing; as a result, automation and mechanization of the processes of pulling and pushing the cassette out of the casing become extremely difficult.

The main disadvantage of this design is the difficulty in maintenance, expressed as:

- in the absence of automation and mechanization of the processes of retraction and ejection of the cartridge from the filter housing;

- in the presence of manual labor when dismantling and removing the cartridge from the filter housing;

- the need to completely remove the cartridge from the filter housing.

The above characteristics affect the performance limited by the speed and physical capabilities of the operator, as well as the impossibility of increasing the technical parameters of the filter by scaling (increasing dimensions), also associated with the presence of restrictions imposed on manual labor.

Disclosure of the invention.

The objective of the invention is to provide a high-performance compact, ergonomic and reliable device for filtering molten plastic, providing the ability to scale the filter when using means of mechanization and automation of the extraction process, filter elements when replacing them.

Technical result:

- productivity increase;

- improving the ergonomics and efficiency of the device;

- facilitation of manual labor with a periodic change of filter elements;

- ensuring the reliability and reliability of the basic filter elements under high internal pressure.

The specified technical result is achieved through the use of a design that includes a housing, which is a hollow steel cylinder with input A, output B holes, internal drainage channels, on the outer surface of which there are heating elements; placed (in working condition) inside the cassette of the cassette, communicating with the internal drainage channels of the casing. According to the invention, the housing, which is a through cylinder in the form of a thick-walled pipe, is not limited to flanges or other similar end elements, thereby providing an axial degree of freedom when moving the cartridge. The cartridge consists of:

- a drainage cylinder, implemented in the form of an all-metal round timber, the outer surface of which is covered with supporting elements;

- support grid, which is a perforated steel sheet, rolled into a cylindrical shell;

- a replaceable filter element, which is a woven steel sieve, wrapped and tightened around a support grid;

- heads;

- end piston.

The drain cylinder is connected to the end piston of the cartridge on one side and the cartridge head on the other. The head and face piston include a clamping disk - an o-ring.

The head of the cartridge is a steel cylinder, structurally made in the form of two successive paired pistons, while in the piston adjacent to the drainage cylinder, there are made radially located through holes for the passage of cleaned plastic, in addition, these pistons have structural elements (grooves) that provide tightness of high and low pressure chambers. The head of the cassette is designed so that the cassette of which it is a part has the ability to repeatedly perform back and forth movements within the housing. The extreme piston of the cartridge head has a design feature for fixing the sealing ring (gasket). The end piston of the cartridge is a single blind metal disk with structural elements ensuring the tightness of the high-pressure chamber, similar to those made on the pistons of the cartridge head (made so that the cartridge, of which it is a part, has the ability to repeatedly perform reciprocating movements inside the case). The pressure disk, which is a threaded element (a large-diameter nut), is screwed onto the end piston of the cartridge on one side and on the cartridge head on the other, presses the o-ring, the deformation and obturation of which ensures the tightness of the chamber with molten plastic mass. In this case, all elements of the cartridge except for the replaceable filter element, o-rings (gaskets) and pressure discs are assembled into a single, non-separable block.

The device pusher can be made in the form of a manual screw drive, as well as with a mechanical transmission driven by an electric motor or with a hydraulic device.

The implementation of the invention was made possible by replacing the fixed end elements (housing flange, cartridge flange) with movable piston cartridges, which assumed the function of containing plastic melt and deforming loads inside the high and low pressure chambers.

The achievement of the technical result is ensured through the use of a design in which the redistribution of loads caused by high pressure accompanying the process of extrusion of plastic occurs in a new, technologically advanced and balanced way, in particular:

- due to the design features of the drainage channels of the housing, allowing you to enter into the high-pressure chamber and remove from the low-pressure chamber a molten plastic, without the use of fixed end elements;

- due to the use of the modified cartridge head and the presence of the cartridge end piston as structural elements to contain internal pressure (now the cartridge head separates not only the high and low pressure chamber, but also the low pressure chamber with the external environment, thus forming a low pressure chamber) ;

- due to the design features of the device as a whole, freedom of axial movement of the filter cartridge is ensured, which makes it possible to mechanize and automate the process of incomplete extraction and subsequent retraction of the cartridge, which allows you to quickly and conveniently change the filter element without completely removing the replacement cartridge from the filter housing (improves performance and ergonomics of use );

- due to the possibility of avoiding manual, complete removal of the removable cartridge, there are no restrictions associated with the physical capabilities of the operator of the filtering process (it becomes possible to scale the filter elements);

- due to the simplicity of geometric shapes (the vast majority of parts are rotation figures), the device acquires high manufacturability in manufacturing, reliability, maintainability and low cost of production on metal cutting machines.

A brief description of the drawings.

In FIG. 1 shows a general diagram of a device for filtering plastic.

In FIG. 2 shows an assembly diagram of a plastic filtering apparatus.

The implementation of the invention

The plastic filtering device shown in FIG. 1, comprises a housing 1 with heating elements 10. The central part of the filtration device, referred to as the cartridge, is an ergonomic movable filtering unit consisting of the following elements: a drainage cylinder 2, a cartridge head 3, an end piston 4, a support grid 6. These basic elements form single non-separable block. A removable filter element 7 is mounted on top of the support grid 6. Threaded clamping disks 9 are screwed onto the cartridge head 3 and the end piston 4. The device for filtering polymer melts has two chambers and two zones, in FIG. 1 zones are marked as follows:

- zone of dirty melt - 11 (to the black dot);

- zone of pure melt - 12 (without points).

Arrow 13 shows the direction of movement of the molten plastic.

The housing 1 of the filtration device is designed to form a high and low pressure chamber, contain the pressure of the plastic mass, and center the assembled cartridge.

The housing 1 is a hollow steel cylinder (for example, a segment of a thick-walled pipe), on the outer surface of which there are heating elements 10. In the housing 1 there are openings for the inlet and outlet of the product. Inside the housing 1 there is a network of redistribution channels of both dirty plastic melt and purified, filtered.

The cartridge as a separate assembly unit performs the function of combining individual parts into one ergonomic element, convenient for periodic, incomplete removal from the housing 1.

Drain cylinder 2 has not undergone modifications (RF patent No. 2523808) and is implemented as an all-metal cylinder with threaded holes on both sides for screwing in the end piston 4 of the cartridge and cartridge head 3. In some cases, a partial selection of metal from the central part of the drain cylinder 2 can be provided in order to facilitate cassettes. The outer surface of the drainage cylinder 2 is covered with a network (array) of support elements, and on one side of the drainage cylinder 2 the turning of the support elements does not reach the edge and cylinder 2 at this point has a smooth surface ("undercut") (see figure 2). This smooth surface is necessary for a snug fit of the support grid 6 and to ensure the tightness of the filter element at the edges, its width is minimal.

Drain cylinder 2 takes on the main load from the molten plastic mass in compression. The design feature associated with the implementation of the "undercut" of the supporting elements from one edge of the drainage cylinder 2 is due to the direction of motion of the filtered flow to the head of the cartridge 3. Thus, the clean melt is removed directly from the filtration area.

The upper parts of the support elements of the drainage cylinder 2 serve as areas of contact with the support grid 6, perceive and distribute the entire load from the pressure of the molten plastic mass.

The supporting grid 6 is a perforated steel sheet rolled into a cylindrical shell and tacked by a longitudinal intermittent weld. This design of the support grid 6 provides a shaping and supporting function for the replaceable filter element 7, while passing through the cleaned melt.

The head of the cartridge 3 is a steel cylinder, structurally made in the form of two sequentially arranged (paired) pistons with through holes in a circle in the body of the piston adjacent to the drainage cylinder. On the one hand, the threaded head of the cartridge 3 is screwed into the drainage cylinder 2. The holes located in one of the end planes coincide in level with the channels formed by the network of supporting elements of the drainage cylinder 2 and exit directly to the low-pressure chamber located inside the head and into the space bounded by it and the inner surface of the housing 1. The outer diameter of the head 3 is limited by the inner diameter of the housing 1.

The head of the cartridge 3 due to its constructive solution performs several functions.

Firstly, it is designed to separate the high-pressure chamber and the low-pressure chamber, into which the clean plastic melt flows through the openings in the head.

Secondly, the cassette head forms, in the space bounded by it and the inner surface of the housing, a low-pressure chamber designed to redistribute and direct the cleaned (filtered) melt into the channel network of the housing towards the exit from it.

Thirdly, it performs the function of a movable (distinguishing feature) end element, balancing and compensating for the shear force of internal high pressure, thereby ensuring containment of the axial tensile force removed from the housing 1.

Due to the above design features, the pusher 5 can be fixed in the end face of the head of the cartridge 3 in various ways (for example, threaded etc.), which provides the application of force to move the cartridge mechanically.

The width of the outer diameter of the second piston of the head of the cartridge 3 has structural elements similar to the first piston, which also creates the necessary tightness between the low-pressure chamber (pure product) and the external environment, prevents the melt from escaping due to the o-ring 8 and the pressure disk 9.

The filter element 7 is a woven steel sieve, wrapped and tightened around the support grid 6. The filter element 7 is designed to separate the dirty melt due to the difference in pressure from both sides and the ability of the filter cells to retain mechanical impurities having a harder structure than the melt with one hand, and the cleaned melt to pass to the other.

The end piston 4 is similar to the head of the cartridge 3 is a metal disk, which is connected to the drainage cylinder 2 and is sealed by a ring 8 under the action of the pressure disk 9.

A device for filtering molten plastic works as follows.

The molten plastic mass moving from the extruder along the production line enters the high-pressure chamber through an opening in the housing “A”. Next, the high-pressure chamber is filled with plastic mass. During the filling process, the plastic uniformly compresses the filter element 7 around the support grid 6. Further, as the pressure rises, the dirty melt is forced through the filter element 7 and the holes in the support grid 6. At the moment the plastic mass passes through the filter element 7, all mechanical impurities are larger filter cells are retained on the surface of the filter element 7. After passing the support grid 6, the purified melt enters the network of support elements formed on rhnosti drain cylinder 2. In the area of the support elements, due to the pressure difference plastic mass is redistributed in the direction of the main flow directed to the output, to the low pressure chamber. The main flow of plastic mass moves along the drainage cylinder 2 along the channels formed by the array of support elements. After passing the drainage cylinder 2, the melt enters the annular gap between the drainage cylinder 2 and the cassette 3 head screwed into it, where it is separated and distributed over the individual holes in the head and then moved to the low-pressure chamber. In the low-pressure chamber, mixing and redistribution of individual flows and their movement along the internal drainage channels of the housing 1 in the direction of the outlet through the hole "B".

As the filter element becomes dirty, the time is approaching to replace the cartridge. After the filter element is completely clogged, the line stops, by means of the pusher 5, the spent cartridge is partially removed from the housing, the filter element 7 is replaced and tightened back into the housing 1. Then the cycle is repeated.

The claimed device differs fundamentally from the device described in patent No. 2523808 in that the loads from the internal pressure are distributed in a new, optimal way: the cassette now restrains the axial load, while the casing only keeps the radial load, while in the prototype the casing held back the loads all directions.

As a result, the invention provides the possibility of mechanization and automation of the process of extracting and retracting a removable cartridge.

Due to the above design features, when the pusher 5 is fixed at the end of the head of the cartridge 3 (Fig. 1), it becomes possible to apply force to the cartridge and free axial movement inside the housing.

Avoiding full removal of the used cartridge when changing the filter element, increasing the speed of its replacement, improving the quality and working conditions of the operator on the line.

The ability to scale the filter and, accordingly, increase the performance of the filtration unit, not only due to the number of filters, but also by increasing the actual filtration area.

The absence of threaded and other devices for fixing the cartridge inside the housing during operation of the filter with internal overpressure.

Simplicity and maintainability when replacing o-rings - the main elements of wear during operation, in contrast to the accompanying wear of the threaded connection of the prototype.

Thus, a solution is proposed for the design of a device for filtering molten plastic, namely, that the housing together with the filter element is implemented in the form of a cylinder. As a result, the performance of the filtering device is increased due to the speed and convenience of changing the filter element (mesh). There is a possibility of mechanization and partial automation of the filtration process. The quality of the filtration line operator and its working conditions are improved.

The developed design provides the opportunity to significantly increase the productivity and efficiency of the device for filtering plastic melts by scaling the filter elements and increasing the filtration surface.

A comparative analysis of the invention showed that the set of essential features of the claimed device for filtering plastic melts is not known from the prior art and therefore meets the patentability condition "Novelty".

In the prior art there were no signs that coincided with the distinguishing features of the invention and affecting the achievement of the claimed technical result, therefore, the invention meets the condition of patentability "Inventive step".

The above information confirms the possibility of using the inventive device for filtering molten plastic in the polymer industry and therefore meets the patentability condition "Industrial applicability".

Claims (4)

1. A device for filtering a molten plastic containing a housing, which is a hollow, through cylinder made of steel, on the outer surface of which there are heating elements, with product inlet and outlet channels and internal drainage channels, a filter unit mounted in the housing and communicating with the housing channels , a drainage cylinder, which is an all-metal cylinder, the outer surface of which is covered with supporting elements, and on one side of the drainage cylinder, the turning of the supporting elements is not goes to the edge and the cylinder in this place has a smooth surface, a removable filter element, which is a woven steel sieve, wrapped and tightened around a support grid, which is made in the form of a perforated steel sheet rolled into a cylindrical shell, while the filter block is a cassette, consisting of a replaceable filter element, support grid, drain cylinder, cartridge head on one side, cartridge end piston on the other side and sealing elements consisting of annular rings threaded rods and clamping disks threaded mounted on the head and end piston, and all cartridge elements except the replaceable filter and sealing elements are assembled into a single non-separable block, while the drain cylinder is connected to the end piston of the cartridge on one side and the cartridge head on the other, the cartridge head represents a steel cylinder, structurally made in the form of two successive paired pistons, and in the body of the piston adjacent to the drainage cylinder, there are through holes in a circle I, and a pusher is installed on the outer front side of the head, the low-pressure chamber is located inside the head and the space bounded by it and the inner surface of the housing, the cartridge end piston is a blind metal disk, made in such a way that the cartridge of which it is a part has the opportunity repeatedly removed and inserted into the housing when replacing the filter element to ensure the tightness of the filter, while the cartridge is not fully removed, and so that the cartridge head does not leave before spruce hull. 2. The device according to p. 1, characterized in that the pusher is made in the form of a manual screw drive. 3. The device according to p. 1, characterized in that the pusher is made with a mechanical transmission, driven by an electric motor. 4. The device according to p. 1, characterized in that the pusher is made with a hydraulic device.

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