DD211314A1 - METHOD AND DEVICE FOR COOLING EXTRUDED PLASTICS - Google Patents

Abstract

The invention relates to a method and a device for cooling extruded strips, such as tubes, profiles, hoses and jacketed wire. The aim is to increase the cooling performance of known Spruehkuehlungen, to reduce the technical-oeconomic production costs, to simplify the operation and maintenance. The task is to improve with simple means the heat transfer coefficient from the cooling medium to the extruded plastic strand. This is achieved through the use of water and air as cooling media, which are fed via separate adjustable piping systems to an injector, where they are mixed and sprayed via supply lines and spray rings as a mixture with a pressure that is greater than d. Part in the air or water supply lines. The sprue rings are designed as a square tube frame and connected at the corner points by cutting ring fittings. The tubes each have a spray hole in the middle. The impact angle of the spray jet is adjustable. The invention can be used for cooling strips produced in the extrusion process.

Description

VEB Plastmaschinenwerk Schwerin Schwerin, 17.8.1982

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Method and apparatus for cooling extruded plastic strands

field of use

The invention relates to a method and a device for cooling continuously extruded th®ra ©] »aitiaröh®n pipes, profiles, hoses or jacketed wires, which are hereinafter referred to as plastic strands ·

Characteristic of the known technical solutions ^v

To cool and stabilize heated, thermoplastic plastic strands emerging from a mold, use is made of Tauoh cooling equipment in the form of water baths or spray cooling baths with spray mist, in which water is finely atomized.

Tauohklihlvorrichtungen have the Hachteil that sioh the profiled, plastic and still warm® material deformed due to the buoyancy forces of the water · The heat transfer coefficient from the cooling medium to the plastic strand is relatively low, since so-called Oberfläehengrenzsohiohten form «

 2Wil (it'982 * O3O73i)

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During the start-up process of the extrusion line, Os can also book water. · This is problematic in the extrusion of hollow profiles, due to the fact that the mold is cooled by the water entering the water. «Due to this the disadvantages of suction cooling have become established · In this process, as described in DI JS 192G, conventional spray nozzles which are annularly directed radially in large numbers onto the strand and which emit water, are "sound" in that there are no harmful buoyancy forces and sufficient heat balance ergo numbers due to the high velocity of the However, be achieved ao £ striking Wassertropfta and di © constant renewal of WasserfiIms _β the major disadvantage of Spröhdttsen is the susceptibility Verschmutsungserseheiiaungen and the high production expense mechaEsieoko · through occurring VerussrsiniguBg © ®; ' In the cooling circle run it comes to the closure © iöselser nozzles »wa® to a reduction in quality of the thus .bly-cooled .Bxtrudate®. drive>. ^: -. ..; .. '.. :' -. _ ^{: v} :.:; V '.''"---- ^ f ^ .X": V;: ^ -''.;·; In DD PS 104 470 a solution b® @ ^ through a koßäentriech © to the extruded b

arranged® doorway »slide with grooving © Yferiehen ^ the cooling medium flows® Di © ring oeuvres are at a certain angle on the heated plastic strand dish · Bin® unevenly cooling, as a result of which iron impurities in the coolant * are present in this cooling process However, this cooling device is very complicated in terms of manufacturing due to the structural design of the outer rear inner body. Furthermore, the angle of attack can not be changed without disassembly and thus interruption of the ezetration process @ .RTM. At eeb.r small or tight annular gap is also a high Dschmungeungege · Larger annular gaps inevitably lead to high consumption of cooling medium and thus energy.

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DE AS 2 164 545 discloses a solution in which water is injected under high pressure into a chamber. The chamber surrounds a wire coated with thermoplastic. The high water pressure draws air in and causes jet flow in the longitudinal direction of the extruded a plastic strand. Lev construction of the chamber is technically very complicated and the cooling device is only suitable for cable sheathing. For pipe extrusion, for example, it is not suitable because the undershot drilling diameters, which are usually run on an extrusion line in time intervals, each time make new suction chambers. Finally, a solution is disclosed in DE OS 2 551 724, in which a sheathed wire is surrounded by a vertical tube, in whose inner wall water drains. The tube has openings through which air is blown. The draining water is sprayed in the direction of the wire. "This vertical arrangement of the cooling device for wires is very effective, but not suitable for the cooling of extruded pipes, hoses and profiles, since the Erfcrusionsrichtung is horizontal here. Λ

Object of the invention

The aim of the invention is to increase the cooling performance in spray cooling, to reduce the technical-economic manufacturing on the wall, to avoid or reduce the susceptibility to interference and to simplify operation and maintenance

Explanation of the essence of the invention

The object of the invention is to increase the Abkleihlgeechgeschwindigkeit of extruded plastic strands duroh an improvement in the heat transfer coefficient from the cooling medium to the extruded plastic strand with a structurally and manufacturing technology simple and reliable device.

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According to the invention this is achieved by a PROCEDURES ", wherein the daa cooling medium from a Wasaer air Gemiech _s ordered wherein the water and the Iiuft is supplied via separate piping systems regulated to an injector in which both are mixed. Upper supply lines and. SprQtaiage is then sprayed this water / air mixture with a bridge that is larger than the partial pressures in the respective air-or water supply lines. The device for carrying out the process is designed so that from a central water line and from a central Compressed air line Branch lines, equipped with adjustable flow valves, must be inserted in an injector, from which supply lines lead to sprinklers or spray bars.

The spray rings are preferably square in shape and consist of tubes which are rotatable about their longitudinal axis, - have a radial bore in the middle and are connected at the corner points by cutting ring screw connections. /SprüJaping.e® ^ is the © rJSitt® / a '> radially adjustable spray head anzuordB @ n »

Ausführuögsbeispie1

The invention will in more detail below on an exemplary embodiment according to ert he will _β The corresponding ¹ show · s. /; . - .. ''. ^{';.' '-'} '/ /' _^\: ^

Pig * 1 '. · .-. , - Draaf looks up;

Pig, 2 - section along the line A ^ according to PigV 1 Jig · 3 - section along the line B-B according to fig * 2 Pig. 4-section along the line C-G according to Pig · 2

Pig. 5 - Top view of a cooling container with spray bars ^:. '-'';^; .-. ^; , '"." .-.

Pig. 6 - Cut to line D-D according to Pig «5

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FIG. 1 shows an embodiment of the invention. The extruded plastic strand 1 passes through the cooling container 2, which consists of a plurality of cooling chambers 2 ^f , 2 ", 2 ·". In KUhlkammorn the spraying area 3 are concentric with the plastic strand 1. The central compressed air line 4 iet provided with branch lines 5, in which flow valves 6 are arranged. In an analogous manner, the central water line 7, branch lines 8, in which flow valve © 9 are arranged. In each case a branch line 5 and 8 open into an injector 10, in which a water-air mixture is generated. From the injector 10, a supply line 11 leads to the spray ring. 3

2 shows a representation of the cooling tank 2 in cross section, with the arrangement of the spray rings 3, and ^άθΓ location of the individual supply lines. The Sprühring 3 consists of straight tubes 12, which are screwed at the ends with cutting ring fittings 13. Each tube 12 has a bore 14 through which the water-air mixture exits. By loosening the cutting ring fittings 13, the tubes 12 can be rotated and the angle of attack "* can be optimally adjusted to any geometric shape of the plastic strand.

In Fig. 3 is a section through a pipe 12 is shown. Another possibility of changing the angle of attack Fig. 4. Each tube 12 is provided with a slot 15. On the tube 12, a spray head 16 is arranged, which is solved by means of the screw 17 and rotated. This gives the bore 18 a new angle of incidence. The spray bodies through which the water-air mixture emerges can also have other shapes, such as spray bars with sufficiently large boreholes from which the spray jet impinges radially on the plastic strand or scattered nozzles , which are directed in the longitudinal direction at an angle to the Estrudat.

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The pig. FIGS. 5 and 6 show an embodiment in which da® cooling medium is sprayed from spray strips 19. BaB has the advantage that it is possible to connect two spray nozzles 19 to a supply line 11.

The injector 10 is formed ale tee, ie ® & two pipelines treffea in a node, mean · "same supply line 11 to continue the ale. Barch that of the flow control valves 6 and 9 "in the branch lines 5" 8 the water-air mixture in pressure and Zusammenset is Zung every single SprOhkörper variably adjustable. The following explains the inventive method and the operation of the associated cooling device course. In the Pig 2 of the embodiment, the / prevailing pressure conditions are shown.

In the central air line 4, the pressure Pjv prevails. With the help of the flow valve 6, the pressure P- iß of the branch line 5 is set. In the central water pipe 7, the pressure P _w prevails. With the help of the flow valve 9, the pressure Pg is set in the branch line 8, In the injector 10, the lüschprozeß. The supply guide 11 of the spray ring contains water of air / air with the pressure P 1 which is greater than the temperature of the supply lines 5 and 8. , , /: ': /'''^; - ^ ^·:; '. '. , ";'.,..''''//-;./':.^': - / ·'" ^\: The water-air Geiadsch escapes through the holes 14 or "18 in a Pom Sprlihstrahles 20 which directed continuously in the longitudinal direction at an angle of incidence q ^ bestiisiaten on the plastic is _β, the angle K between 90 ° and 0 °, and is respectively by the rotatable in the Schiaeidringversohraubuögen 13 tubes 12 · the adjustable via a screw 17 the spray heads 16 adjustable.

The intensity of the spray is dependent on the pressures P ₁ and P ₂ , in front of the injector 10 in the branch line

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prevail for air 5 and 8 water and are set via the valves 6 and 9.

The mixture can therefore predominantly air or water or both in equal parts depending on deo pressures P ₁ and? _{2 included} in the branch lines 5 and 8. The pressure P 1 and thus the flow velocity of the water-air mixture can be adjusted via the flow valves 6 and 9. By switching off the water at individual spray rings or strips, drying of the extruded plastic strand can also be achieved by pure air cooling.

The advantages of the solution according to the invention are that the production costs for the cooling device are very low. The spray rings are only needed for straight tubes, which are assembled with standard compression fittings. The coolant, which consists of a water-air mixture and is sprayed on the outer high pressure, achieves a high cooling rate for the extruded plastic strand. The heat transfer is thus very effective, which means high output rates are achieved with short cooling sections. The spray treatment according to this solution is very reliable. The holes 14 and 18 may be 2-3 mm in diameter. Any incoming impurities can be quickly removed with a wire or hail during the extrusion process. However, contamination of the few relatively large bores is hardly conceivable, since the flow rate of the water-air mixture does not permit such. Due to the variability dee pressure and the composition of the water-air mixture at each Sprühring are different variants, such as cooling and drying only with air, at the end of the cooling section, cooling only with water uew. possible. ;

Claims (4)

claims 242 7 23 b 1. A method for KUhIeη of extruded plastic strand,: ^< in which on the extruded plastic strand via a line system, a pressurized cooling medium g © sprayed, characterized in that the cooling medium consists of a water-air mixture, wherein the water and the air is supplied to an injector (10) via separate controllable piping systems, bled into the injector (10) and sprayed via supply lines (11) and spray rings (3) as a washer-air mixture at a pressure greater than the parts of the respective air or water supply lines (4, 7). 2. Apparatus for carrying out the method for cooling extruded plastic strands according to item 1, consisting of a box-shaped cooling container with inlet and outlet lines for the cooling medium, wherein the Eaflußleitungen end in a spray ring with radial Auetrittsbohrungen, characterized in that from a central water pipe ( 7) and from a central compressed air line (4) branch lines (5) and (8), which are provided with adjustable Strömusgsventilen (6) tew «(9), in an injector (10) open, from which supply lines (11) lead to the spray units (3) or spray bars (19). 3. The device according to item 2, characterized in that the spray rings (3) are preferably square formed and consist of tubes which are rotatable about its longitudinal axis, one or mehrer® have radial holes and at the Eokpunkten by Schneia ^ ingverschraubüngen (13 connected are. '.''"·..''.' ^: """'..: * ..''''.;":.:::".<'^::;;>.". 4. Apparatus according to item 2 and 3, characterized in that preferably four radially adjustable spray heads (16) are arranged on the spray rings (3). For this S sides Zeichniinnen