RU2213007C2 - Device for filtering of polymer material melt - Google Patents

Abstract

FIELD: process equipment for manufacture of products from plastic by extrusion or casting methods; applicable in polymer industry. SUBSTANCE: device has body, movable unit with changeable filter screens, system for moving of said unit by polymer melt being under extrusion pressure and adapter flanges. The latter serve for fastening of body to extruder and forming head to body. System for moving the unit with changeable filter screens includes cylinders with pistons installed on body two sides. Cylinders are connected with channels of adapter flange connected with forming head by means of channels with shutoff valves. Cylinders are provided with locking gate valves, and body, with removable plugs installed during replacement of filter screens. Adapter flanges, cylinders channels connecting cylinders with adapter flanges and shutoff valves are provided with heating members. Filter screen area exceeds that of cylinder cross-section. Distance between filter screens in moving unit is within 0.1D, where D is diameter of filtering surface of screen. EFFECT: improved design with replacement of filter screens without interruption of production process. 2 dwg

Description

 The invention relates to technological equipment for the manufacture of plastic products by linear or injection molding and can be used in the polymer industry.

 The design of the device of the Institute "UkrNII Plastics" for filtering the melt of polymeric materials and replacing the used filter screens with the drive of the mobile unit manually, pneumatically or hydraulically.

 The disadvantage of this design is the interruption of the process when changing filter screens (stopping machines).

 Known design Aufban-SWE Germany, consisting of a housing, a replacement lattice of sieve bolts, a hydraulic drive station and a hydraulic system in which the filter sieves are replaced without interrupting the process (Operating instructions for the replacement of gratings (sieves) SWC-121, release - February 1999 company Aufban-SWE Germany).

 The disadvantage of this design is the complexity of the design and maintenance in the presence of a hydroelectric station and an oil hydraulic system, high cost, the need for a control system controller.

 The technical result of the invention is the creation of a filter for filtering the melt of polymeric materials, which allows filter sieves to be replaced without interrupting the process using a working extrusion system of polymeric materials and obtaining products directly on the line.

 To achieve a technical result in a device for filtering a melt of polymeric materials, comprising a housing, a mobile unit with replaceable filter screens, a system for moving said unit with a molten polymer under extrusion pressure, and adapter flanges for attaching the housing to the extruder and the forming head on the housing, according to the invention the block moving system with replaceable filter screens includes cylinders with pistons mounted on both sides of the casing, connected to channels connected to the forming head of the transitional flange through channels with shut-off valves, while the cylinders are equipped with shut-off valves, and the housing is equipped with removable plugs installed on it when changing filter screens, the transitional flanges, cylinders, channels connecting the cylinders to the transitional flange, and shut-off valves are equipped with heating elements, the filter sieve area is larger than the internal cross-sectional area of the cylinder, and the distance between the filter sieves in the mobile unit is not more than 0.1 D, where D is the diameter of the filter surface with ta.

 The technical result obtained from the use of the invention is achieved through cylinders with pistons connected by channels to the extrusion system of the screw press. The filtration system has valves and gate valves that are automatically controlled. The pressure in the extrusion system is Re≥100 atm and is set depending on the geometry of the profile of the molded product and material. When the sieve is clogged with foreign inclusions, the extrusion pressure increases at P1> Pe by 10-15%, the system for heating the valve channels and shut-off valves is turned on, with a further increase in P2> Pe by 15-20%, the filter change system is activated. In the filter change mode, t <1-1.5 s at Pe> 100 atm. The distance between the filter sieves of not more than 0.1 D has a minimal effect on the extrusion process and is structurally feasible. The replaced sieve works for a certain time with the primary polymer on the order of 24 hours, with the secondary polymer less depending on the degree of contamination of the material.

 Comparative analysis with the prototype shows that the inventive device performs all the technological functions of the prototype and further simplifies the technology of work, maintenance, energy saving and reliable operation.

 Figure 1 shows a filter for filtering the melt of polymeric materials.

 Figure 2 shows a mobile unit 10 with a filter sieve.

 A device for filtering the melt of polymeric materials is a housing 1, which is mounted on the extruder of polymer materials 3 by a transitional flange 2, and a forming head (mold) is fixed to it through the transitional flange 4 5. A cylinder 6 with a piston 7 is attached to the right of the housing 1, on the left is a cylinder 8 with a piston 9. Inside the housing is a mobile unit 10 with filter screens. Locking gates 12 are installed on cylinders 6 and 8. Cylinders 6, 8 are connected to the channels of the adapter flange 4 by means of channels 13, 14 through the shutoff valve 15. When changing the filter screens, removable plugs 16 are installed on the housing.

 Adapter flanges 2, 4, cylinders 6, 8, channels 13, 14 and shut-off valves 15 are equipped with heating elements 17.

 The operation of the device for filtering the melt of polymer materials is as follows.

 The polymer melt supplied from the extruder in the direction of arrow A through the adapter flange 2 is filtered through a filter sieve 11 located in one of the two slots of the mobile unit 10 and sent to the forming head (mold) 5, where a profile or a polymer casting is formed ( pipes, molded profiles, cast parts, etc.).

 When filtering sieves are filled with waste, the productivity of the process decreases by 10-15% (the percentage reduction is determined by the technological regulations of the production).

 It is necessary to replace the used filter sieve with a new one (washed sieve plate 20 and grating of the sieve package).

 Replacement is as follows.

 On the body, removable plugs 16 are installed that do not leak the melt during the replacement period.

 The heating elements of the cylinder 8, channels 13, 14 and the shut-off valve 15, usually consisting of a ball valve with an electromagnetic actuator located on the left side of the filter, are turned on.

 The locking gate 12 to the left of the filter is set to the "closed" position, to the right - to the "open" position. At this point, both shutoff valves 15 are in the closed position.

 When the melt in the channels 13, 14 and the shut-off valve 15 on the left side of the filter reaches the set temperature, the valve 15 is introduced into the "open" position.

The melt under pressure> 100 bar flows through the channels 13, 14 into the cavity of the cylinder 8 and the piston 9 moves to the extrusion center, moving the mobile unit 10 with filter sieves 11. In this case, the piston 7 pushes the core through the gate 12 in the "open" position solidified melt 18 remaining from the previous change of filter screens. The filter screen change scheme corresponds to the operation of a classical hydraulic system. The melt of the plasticizable polymer of polyethylene and the Sevilen copolymer at a temperature of +146 ^o C is extruded at a pressure of P> 100 bar, which is the normal pressure of the oil hydraulic system with a working fluid IS 40. The core of the solidified melt 18 from the previous replacement of the filter sieves acts as a damper.

 After the installation of the mobile unit 10 with filter screens 11 in the right position is completed, the shut-off valve 15 is inserted into the "closed" position on the left side and the heating elements on the cylinder 8, channels 13, 14 and the shut-off valve 15 are turned off. The removable plugs 16 are removed in the direction of arrow B and core 19 with a used filter screen is removed. A new sieve is installed in the right cavity of the mobile unit 10, and the cores 18, 19 are sent to the extruder loading device for recycling. When working out the filter sieve 11 in the extrusion process, the sieves are replaced in the same order from the right to the left side of the filter. As shown in FIG. 2, filter screens commonly used in extruders have a relatively small filter surface area equal to the internal cross-sectional area of the cylinder.

 In the proposed design of the filter, the filtering surface of the sieve is formed by a circle area with a diameter D. The internal cross-sectional area of a cylinder having a diameter d is smaller than the area of a sieve with a diameter D, which allows less frequent replacement of sieves clogged with foreign inclusions with a clean sieve. The minimum jumper B (Fig. 2), separating the filter elements, has a size of not more than 0.1 D, which allows practically no overlap of the cylinder area with segments of the mobile unit RO when changing screens, while ensuring the continuity of the process and the absence of pulsation of the molten plastic.

Claims (1)

 A device for filtering the melt of polymeric materials, comprising a housing, a mobile unit with replaceable filter screens, a system for moving the specified unit with a polymer melt under extrusion pressure, and adapter flanges for attaching the housing to the extruder and the forming head on the housing, characterized in that the unit has a moving system with replaceable filter sieves includes cylinders with pistons mounted on both sides of the casing, connected to the channels of the transitional flange connected to the forming head by means of channels with shut-off valves, while the cylinders are equipped with shut-off gates, and the housing is equipped with removable plugs installed on it when changing filter screens, and transition flanges, cylinders, channels connecting the cylinders with the transition flange, and shut-off valves are equipped with heating elements, the filter area the sieve is larger than the internal cross-sectional area of the cylinder, and the distance between the filtering sieves in the mobile unit is not more than 0.1D, where D is the diameter of the filtering surface of the sieve.

Images