RU2523808C1 - Device for filtration of polymer melts - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: proposed device comprises casing with inlet, outlet and drain channels, heaters arranged on casing outer surface, filter unit built in said casing communicated with casing channels. Said casing is composed by hollow steel cylinder. Filter element is composed of cartridge consisting of replaceable filter element, bearing grate, drain cylinder, head and cartridge flange. All cartridge elements apart from replaceable filter element are assembled to integral one-piece unit. Drain cylinder is composed of all-metal rod connected with cartridge flange on one side and, on opposite side, with cartridge head. Drain cylinder outer surface is coated with truncated pyramid elements. On one side of drain cylinder turning of pyramidal elements does not extend to the edge for cylinder to have smooth surface at said point. Replaceable filter element represents a woven steel screen wrapped and tightened around bearing grate. Bearing grate is composed of perforated steel sheet rolled to cylindrical shell. Cartridge head is composed of steel cylinder composed by piston with holes made in circle. Cartridge flange represents a blank metal disc made so that cartridge of which said disc is a part can be fitted in and out many times and is tightly secured to the casing. Casing flange is a metal disc. There is the joint with cartridge flange on one side and with casing flange on opposite side. Both ends of the casing have circular groove for dowelled joint.EFFECT: higher efficiency.2 cl, 4 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 is known for filtering the melt of polymeric materials (RF patent No. 2213007, September 27, 2003), comprising a housing, a mobile unit with replaceable filter screens, a system for moving said unit with a polymer melt under extrusion pressure, and adapter flanges. Adapter flanges are used to mount the housing on the extruder and the forming head on the housing. The block movement system with replaceable filter screens includes cylinders with pistons mounted on both sides of the housing. The cylinders are connected to the channels of the transitional flange connected to the forming head by means of channels with shut-off valves. The cylinders are equipped with locking gates, and the housing is equipped with removable plugs installed on it when changing filter screens. Adapter flanges, cylinders, channels connecting the cylinders to the adapter flange, and shut-off valves are provided with heating elements. The area of the filter sieve is greater than the area of the internal section of the cylinder. The distance between the filter screens in the mobile unit is not more than 0.1 D, where D is the diameter of the filter surface of the sieve.

A disadvantage of the known device is the relatively low productivity of the melt filtration of polymeric materials.

The closest to the proposed purpose and the combination of essential features is an extrusion line filtering device (USSR author's certificate No. 1691122, 11/15/1991), in the housing of which a cylindrical shell is mounted with the ability to move perpendicular to the central axis of the head. The latter is equipped with a central core, end caps for attaching filtering elements. They form accumulating and unloading chambers with a shell and caps. The cameras are in communication with the channels of the housing by feeding, unloading, make-up and drain channels, made in the central core. In this case, the make-up channels are made on the outer surface of the central core with output sections aligned with the input sections of the supply channels. Drain channels are made on the outer surface of the core diametrically opposite to the make-up channels with input sections aligned with the output sections of the discharge channels. The bypass channel of the housing is located diametrically opposite to its drainage channel and has a U-shape.

The disadvantage of this design is the complexity of the design and maintenance, as well as the relatively low productivity and efficiency of the device for filtering the melt of polymeric materials.

Disclosure of the invention.

The present invention is the creation of a high-performance compact, ergonomic and reliable device for filtering the melt of polymeric materials, providing the ability to replace filter elements.

EFFECT: increased productivity, ergonomics and overall performance of a device for filtering polymer melts.

The specified technical result is achieved in that the device for filtering polymer melts comprises a housing with inlet, outlet and drainage channels, on the outer surface of which there are heating elements, a filtering unit mounted in the housing communicating with the channels of the housing, and according to the invention, the housing is a hollow steel cylinder; the filtering unit is a cartridge, consisting of a replaceable filtering element, a support grid, a drainage cylinder, a head and a flange of a cartridge, while all elements of the cartridge, except for a replaceable filtering element, are assembled into a single, non-separable block; the drainage cylinder is implemented as an all-metal rod connected to the cartridge flange on one side and the cartridge head on the other, the outer surface of the drainage cylinder is covered with truncated pyramidal elements, and on one side of the drainage cylinder the turning of the pyramidal elements does not reach the edge and the cylinder in this place has smooth surface; the replaceable filter element is a woven steel screen wrapped and tightened around a support grid, the support grid is a perforated steel sheet rolled into a cylindrical shell; the cartridge head is a steel cylinder, structurally made in the form of a piston with holes in a circle; the cassette flange is a blind metal disk, made in such a way that the cassette of which it is a part has the ability to be repeatedly removed and inserted into the housing, while being securely attached to the housing, the housing flange is a metal disk; at the ends of the housing on both sides, a connection is provided with the cartridge flange on one side and the housing flange on the other so as to ensure reliable fastening, and the housing has an annular groove at both ends to create a thorn-groove sealing joint with a gasket. Moreover, the housing flange may contain an outlet in the center of the metal disk. The achievement of the technical result is provided by:

- due to the design features of the high-pressure chamber and the distribution of plastic mass flows, the “dirt capacity” increases many times (a quantitative description of the volume of dirt extracted from the melt and held within the high-pressure chamber);

- due to the design feature of removable cartridges, the “actual filtration area” (quantitative characteristic of the surface area of the filter element that it is in contact with the high-pressure chamber) has increased many times;

- due to the design feature of removable cartridges, the “area of the active surface of the filter element” has increased many times (a quantitative characteristic of the surface involved in the “actual area of the filter” of the filter element through which the plastic mass is simultaneously pressed);

- due to the large "area of the active surface of the filter element" the resistance to the current of the plastic is repeatedly reduced, which leads to an increase in the productivity of extrusion lines as a whole;

- by reducing the resistance to the current of the plastic, the potential for using filtering elements with ultra-small filtering cells in the filtering process increases, which leads to an improvement in the fineness (purity) of the filtration;

- due to the design features of removable cartridges, a high-pressure chamber and distribution of plastic mass flows, the “effective filtration area” (quantitative characteristic of the product “active surface area of the filter element” and “dirt capacity”) has increased significantly;

- due to the design features of the device as a whole, which allows quickly and conveniently changing interchangeable cartridges, the productivity and ergonomics of use are improved;

- due to the simplicity of geometric shapes, the device acquires high manufacturability and low cost of production on metal cutting machines.

A brief description of the drawings.

Figure 1 shows a General diagram of a device for filtering polymer melt.

Figure 2 shows a General diagram of a device for filtering a polymer melt with an alternative output.

Figure 3 shows a drainage cylinder with an array of pyramidal elements.

Figure 4 shows the assembly diagram of a device for filtering polymer melt.

The implementation of the invention

A device for filtering polymer melts comprises a housing 1 with a heating element 6, an end flange 8, a sealing connection 9. The central part of the filtering device, referred to as a cartridge, is an ergonomic removable filter unit consisting of the following elements: filter element 2, support grid 3, drainage cylinder 4, cartridge head 5, cartridge flange 7. The device for filtering polymer melts has two chambers and two zones, in figures 2 and 3 they are marked accordingly:

- high-pressure chamber - dark gray;

- low pressure chamber - light gray;

- zone of dirty melt - to a black dot;

- zone of pure melt - without points.

The housing 1 of the filtering device is designed to form a chamber of high and low pressure, restraining the pressure of the plastic mass, ensuring the fastening of the end flange 8 and the cartridge assembly.

The housing 1 is a hollow steel cylinder (for example, a section of a thick-walled pipe), on the outer surface of which there are heating elements 6. On the inner surface on both sides there are threaded connections for mounting the flange of the cartridge 7 on one side and for the flange of the housing 8 of the low-pressure chamber with other. At both ends, the housing 1 has an annular groove for creating a thorn-groove-type sealing joint 9 with a gasket.

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

The drainage cylinder 4 is implemented as an all-metal rod with threaded holes on both sides for screwing in the flange of the cartridge 7 and the head of the cartridge 5. In some cases, a partial selection of metal from the central part may be provided in order to facilitate the cartridge. The outer surface of the drainage cylinder 4 is covered with a network (array) of truncated pyramidal elements, moreover, on one side of the drainage cylinder 4, the turning of the pyramidal elements does not reach the edge and cylinder 4 has a smooth surface at this point ("undercut") 10. This smooth surface is necessary for dense fit support grid 3 and ensure the tightness of the filter element at the edges, its width is minimal.

Drain cylinder 4 takes on the main load from the molten plastic mass in compression. A design feature associated with the implementation of "undercut" of the pyramidal elements from one edge of the drainage cylinder 4 is due to the direction of motion of the filtered flow to the head of the cartridge 5. Thus, the clean melt is removed directly from the filtration area.

The upper parts of the pyramidal elements serve as areas of contact with the support grid 3, perceive and distribute the entire load from the pressure of the molten plastic mass.

The support grid 3 is a perforated steel sheet rolled into a cylindrical shell and tacked by a longitudinal intermittent weld. This design of the support grid 3 provides a shaping and supporting function for the replaceable filter element 2, while passing through the cleaned melt.

The head of the cartridge 5 is a steel cylinder, structurally made in the form of a piston with holes in a circle. On the one hand, the threaded head of the cartridge 5 is screwed into the drainage cylinder 4. The holes located in one of the end planes coincide in level with the channels formed by the network of pyramidal elements of the drainage cylinder 4 and exit directly into the low-pressure chamber. The outer diameter of the head 5 is limited by the inner diameter of the housing 1.

The head of the cartridge 5 due to its constructive solution performs several functions. First of all, it is intended for the separation of the high-pressure chamber and the low-pressure chamber, into which the net plastic melt flows through the openings in the head.

The width of the outer diameter of the head of the cartridge 5 creates the necessary tightness due to the high viscosity of the melt, as well as the closing ability of its structural elements, made in the form of annular grooves deposited on the surface of maximum diameter. Due to this, it seems possible to avoid excessive precision accuracy in the manufacture of the inner diameter of the housing 1 and the outer diameter of the head of the cartridge 5. An important problem is being solved - ensuring tightness between the high-pressure chamber and the low-pressure chamber.

The flange of the cartridge 7 is a blind metal disk, which is securely attached to the drain cylinder 4. Together with the drain cylinder 4 and other elements of the cartridge, it is a single non-separable block cartridge connected to the housing 1, and sealed between them by a gasket laid in a sealing connection 9 (annular groove of the type "spike - groove").

The flange of the cassette 7 performs two functions: it is a composite non-separable element of the cassette, which accepts part of the internal pressure of the medium and prevents the melt from escaping due to the end sealing connection 9 with the housing 1. The flange 7 is connected to the housing 1 through a threaded connection, thereby providing ergonomic periodically removing the cartridge with a used replacement filter element and replacing it with another cartridge with a new filter element, in its entirety.

The filter element 2 is a woven steel sieve, wrapped and tightened around the support grid 3. The filter element 2 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 flange of the housing 8, similarly to the flange of the cartridge 7, is a metal disk that is connected to the housing 1 and sealed with a gasket laid in an annular groove of the "spike-groove" type. The housing flange may comprise an outlet in the center of the metal disk.

The flange of the housing 8 is an element of restriction of the low-pressure chamber, and also performs the function of directing the filtered flow through the hole "B" for the next stage of processing and molding of the purified melt.

A device for filtering polymer melts 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 2 around the support grid 3. Further, as the pressure increases, the dirty melt is forced through the filter element 2 and the holes in the support grid 3. At the moment the plastic mass passes through the filter element 2, all mechanical impurities more than the size of the filter cell, they are retained on the surface of the filter element 2. After passing through the support grid 3, the purified melt enters the network of truncated pyramidal elements, grammed on the surface of the drainage cylinder 4. From the zone of truncated pyramids, due to the pressure difference plastic mass is redistributed in the direction of the main flow directed to the output from the cartridge to the low pressure chamber. The main flow of plastic mass moves along the drainage cylinder 4, along the channels formed by the array of truncated pyramids. After passing the drainage cylinder 4, the melt enters the annular gap between the drainage cylinder 4 and the cassette 5 head screwed into it, where it is separated and distributed over the individual holes in the head and further moves into the low-pressure chamber. In the low-pressure chamber, mixing and redistribution of individual streams towards the outlet through the opening "B" occurs.

As the filter element becomes dirty, the time is approaching to replace the cartridge. After the filter element is completely clogged, the line stops, and the spent cartridge is removed from the housing, and another replaceable one with a clean filter element is inserted in its place. Then the cycle repeats, and the spent cartridge goes to replace the replaceable filter element.

Thus, a new solution is proposed for the design of a device for filtering polymer melts, 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 several times, for example, compared with the filtering devices of slide and disk design, in which the working surface is represented only in one plane.

The developed design provides a significant increase in the productivity and efficiency of the device for filtering polymer melts.

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

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

The above information confirms the possibility of using the inventive device for filtering polymer melts in the polymer industry, and therefore meets the patentability condition "Industrial Applicability".

Claims (2)

1. A device for filtering polymer melts, comprising a housing with inlet, outlet and drainage channels, on the outer surface of which there are heating elements, a filter unit mounted in the housing, communicating with the channels of the housing, characterized in that the housing is a hollow steel cylinder; the filtering unit is a cartridge, consisting of a replaceable filtering element, a support grid, a drainage cylinder, a cartridge head and a flange, while all elements of the cartridge except the replaceable filtering element are assembled into a single, non-separable block; the drainage cylinder is implemented as an all-metal rod connected to the cartridge flange on one side and the cartridge head on the other, the outer surface of the drainage cylinder is covered with truncated pyramidal elements, and on one side of the drainage cylinder the turning of the pyramidal elements does not reach the edge and the cylinder in this place has smooth surface; the replaceable filter element is a woven steel sieve wrapped and tightened around a support grid; the support grid is a perforated steel sheet rolled into a cylindrical shell; the cartridge head is a steel cylinder, structurally made in the form of a piston with holes in a circle; the cassette flange is a blind metal disk, made in such a way that the cassette of which it is a part has the ability to be repeatedly removed and inserted into the housing, while being securely attached to the housing, the housing flange is a metal disk; at the ends of the housing on both sides, a connection is provided with the cartridge flange on one side and the housing flange on the other so as to ensure reliable fastening, and the housing has an annular groove at both ends to create a thorn-groove sealing joint with a gasket. 2. The device according to claim 1, characterized in that the housing flange contains an outlet in the center of the metal disk.

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