SE500696C2 - Procedure for extrusion of plastic pipes - Google Patents

Procedure for extrusion of plastic pipes

Info

Publication number
SE500696C2
SE500696C2 SE8900845A SE8900845A SE500696C2 SE 500696 C2 SE500696 C2 SE 500696C2 SE 8900845 A SE8900845 A SE 8900845A SE 8900845 A SE8900845 A SE 8900845A SE 500696 C2 SE500696 C2 SE 500696C2
Authority
SE
Sweden
Prior art keywords
heating elements
wall thickness
pipe
extruder
calibrator
Prior art date
Application number
SE8900845A
Other languages
Swedish (sv)
Other versions
SE8900845D0 (en
SE8900845L (en
Inventor
Paul Hoelsoe
Untamo Ruohola
Original Assignee
Uponor Nv
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Uponor Nv filed Critical Uponor Nv
Priority to SE8900845A priority Critical patent/SE500696C2/en
Publication of SE8900845D0 publication Critical patent/SE8900845D0/en
Priority to PCT/SE1990/000154 priority patent/WO1990010530A1/en
Publication of SE8900845L publication Critical patent/SE8900845L/en
Publication of SE500696C2 publication Critical patent/SE500696C2/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/908—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article characterised by calibrator surface, e.g. structure or holes for lubrication, cooling or venting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
    • B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
    • B29C48/865—Heating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/903—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies externally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/919—Thermal treatment of the stream of extruded material, e.g. cooling using a bath, e.g. extruding into an open bath to coagulate or cool the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/92—Measuring, controlling or regulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92009—Measured parameter
    • B29C2948/92114—Dimensions
    • B29C2948/92152—Thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92323—Location or phase of measurement
    • B29C2948/92428—Calibration, after-treatment, or cooling zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92609—Dimensions
    • B29C2948/92647—Thickness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92504—Controlled parameter
    • B29C2948/92704—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2948/00—Indexing scheme relating to extrusion moulding
    • B29C2948/92—Measuring, controlling or regulating
    • B29C2948/92819—Location or phase of control
    • B29C2948/92857—Extrusion unit
    • B29C2948/92904—Die; Nozzle zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/904—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article using dry calibration, i.e. no quenching tank, e.g. with water spray for cooling or lubrication
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/911—Cooling
    • B29C48/9115—Cooling of hollow articles
    • B29C48/912—Cooling of hollow articles of tubular films
    • B29C48/913—Cooling of hollow articles of tubular films externally

Abstract

Method for extruding plastic pipes from an extruder nozzle having a number of heating elements (26A, 26B, 26C) which are distributed circumferentially around the extruder nozzle (10A). The wall thickness of the extruded pipe is measured by means of ultrasound in a number of measuring positions (19A, 19B, 19C) distributed around the pipe, said measuring positions corresponding to the number of heating elements in the extruder nozzle and being located on the calibrator sleeve (16) in a vacuum or pressure calibrator (12) forming part of the extruder line. The power of the heating elements is controlled in dependence of measured thickness values for adjusting the surface friction and thus the wall thickness in the sections of the pipe wall, corresponding to the heating elements.

Description

15 20 25 30 35 sker, är beläget pà stort avstànd frän extrudern - det x är fräga om ett avstànd pä 15 a 20 meter - blir res- ponsen i regleringen trög, eftersom det tar läng tid, innan det parti av röret, som lämnar extrudermun- stycket efter ändrad inställning av värmeeffekten, när fram till mätstället och det sålunda tar läng tid, innan reglersystemet indikerar och korrigerar even- tuellt förekommande avvikelse. Även av en annan anled- ning är emellertid placeringen av mätstället otill- fredsställande. När röret lämnar kylrännan, har det redan skinn pá sàväl utsidan som insidan, eftersom det genomgått kylning först i den omedelbart efter extru- dermunstycket anordnade kalibratorn och sedan i kyl- rännan, där röret sprayas med vatten frän ovanför rö- ret anordnade dysor. Pà grund av kylningen av röret pà detta sätt i kylrännan, kommer röret inte att ha ens- artad temperatur pà plastmaterialet mellan skinnen över hela sin omkrets. Temperaturen är lägre i rörets övre parti än i dess nedre parti. Eftersom mätningen av väggtjockleken medelst ultraljud är beroende av materialets temperatur, kan mätningen och regleringen inte ske med den noggrannhet som vore önskvärd. Följ- den härav är att man häller gott mätt pá väggtjock- leken för att inte komma under det lägre toleransvär- det. Med tanke pä att materialkostnaden svarar för ca 75% av den totala tillverkningskostnaden för röret, innebär detta en icke oväsentlig merkostnad vid till- verkningen. Det är naturligtvis mest ekonomiskt att kunna hälla väggtjockleken sä nära det lägre tolerans- värdet som möjligt utan risk för att detta värde underskrides. 15 20 25 30 35 takes place, is located at a great distance from the extruder - it x is a distance of 15 to 20 meters - the response in the regulation becomes sluggish, because it takes a long time before the part of the tube that leaves the extruder nozzle after changing the setting of the heating effect, reaching the measuring point and it thus takes a long time, before the control system indicates and corrects any deviation. Also for another reason, however, the location of the measuring point is unsatisfactory. When the pipe leaves the cooling gutter, it already has skin on both the outside and the inside, as it has been cooled first in the calibrator arranged immediately after the extruder nozzle and then in the cooling gutter, where the pipe is sprayed with water from above the pipe. Due to the cooling of the pipe in this way in the cooling gutter, the pipe will not have a uniform temperature on the plastic material between the skins over its entire circumference. The temperature is lower in the upper part of the tube than in its lower part. Since the measurement of the wall thickness by means of ultrasound depends on the temperature of the material, the measurement and regulation cannot be done with the accuracy that would be desirable. The consequence of this is that you pour well measured on the wall thickness so as not to fall below the lower tolerance value. Considering that the material cost accounts for about 75% of the total manufacturing cost of the pipe, this means a not insignificant additional cost during production. It is of course most economical to be able to pour the wall thickness as close to the lower tolerance value as possible without the risk of this value being exceeded.

Till detta kommer sä att anordningen för att driva ultraljudsensorn i en bana runt plaströret är komplicerad och lätt blir utsatt för driftstörningar och att mät- och reglersystemet är svärt att trimma in. 10 15 20 25 30 35 500 696 Trots de uppenbara nackdelarna med det nu före- kommande mät- och reglersystemet, har det hittills inte framkommit nàgot annat, bättre system.In addition, the device for driving the ultrasonic sensor in a path around the plastic pipe is complicated and easily exposed to operational disturbances and that the measuring and control system is difficult to tune in to. 10 15 20 25 30 35 500 696 Despite the obvious disadvantages of the current measurement and control system, so far no other, better system has emerged.

Uppfinningen har tillkommit i syfte att möjlig- göra en mera noggrann och tillförlitlig mätning och reglering med enklare och driftsäkrare utrustning Enligt uppfinningen avses sàlunda ett sätt vid extrudering av plaströr frän ett extrudermunstycke med ett antal värmeelement, som är fördelade periferiellt omkring extrudermunstycket, varvid det extruderade rörets väggtjocklek mätes medelst ultraljud pà ställen utmed rörets omkrets och effekten i värmeelementen regleras i beroende av uppmätta tjockleksvärden för reglering av friktionen och därmed väggtjockleken i de mot vàrmelementen svarande sektorerna av rörväggen, varvid detta sätt i angivet syfte erhållit de känne- tecken som framgàr av patentkravet 1.The invention has been developed for the purpose of enabling a more accurate and reliable measurement and control with simpler and more reliable equipment. the wall thickness of the pipe is measured by means of ultrasound in places along the circumference of the pipe and the effect in the heating elements is regulated in dependence on measured thickness values for regulating the friction and thus the wall thickness in the heating wall corresponding sectors of the pipe element. claim 1.

Att förlägga mätställena till kalibratorn har hittills inte ansetts vara lämpligt eller ens möjligt, eftersom kalibratorn är en förhållandevis komplicerad apparat i extruderlinjen, antingen den är av vakuumtyp eller övertryckstyp, dà den inneháller ett antal ven- tiler och pumpar för luft och kylvatten, och inte heller har man tidigare insett att man därigenom skulle kunna vinna nägra fördelar. Tvärtom har det varit den allmänna uppfattningen att ingrepp i kalib- ratorn skulle kunna leda till drift- och kvalitets- störningar. När nu mätningen vid sättet enligt uppfin- ningen likväl sker i kalibratorn stick i stäv mot vad som ansetts lämpligt eller möjligt, har det visat sig att man därigenom utan att i nagot avseende äventyra extruderlinjens funktion uppnår en betydligt mera exakt reglering av väggtjockleken. Detta torde i första hand bero pà att materialet i rörväggen vid passagen genom kalibreringshylsan ännu har ett tämli- 500 696 10 15 20 25 30 35 gen homogent temperaturtillstànd runt rörets omkrets, dä röret efter att ha lämnat extrudern ännu inte har hunnit kylas ned under uppkomst av temperaturdifferen- ser i rörmaterialet, sä att en tillförlitlig tjock- leksmätning kan ske i mätpunkterna, men också pà att responsen i regleringen blir snabbare, eftersom mät- punkterna befinner sig avsevärt närmare extrudermun- stycket, högst ca 0,5 meter frän denna.The location of the measuring points to the calibrator has not hitherto been considered suitable or even possible, since the calibrator is a relatively complicated apparatus in the extruder line, whether it is of the vacuum type or the overpressure type, as it contains a number of valves and pumps for air and cooling water, and not nor has it been realized before that one could thereby gain some advantages. On the contrary, it has been the general opinion that intervention in the calibrator could lead to operational and quality disturbances. Now when the measurement according to the method according to the invention nevertheless takes place in the calibrator contrary to what is considered appropriate or possible, it has been found that a much more precise regulation of the wall thickness is thereby achieved without compromising the function of the extruder line. This is primarily due to the fact that the material in the tube wall during the passage through the calibration sleeve still has a fairly homogeneous temperature condition around the circumference of the tube, as the tube after leaving the extruder has not yet had time to cool down during formation. of temperature differences in the pipe material, so that a reliable thickness measurement can take place at the measuring points, but also that the response in the regulation is faster, since the measuring points are considerably closer to the extruder nozzle, no more than about 0.5 meters from it.

För närmare förklaring av uppfinningen hänvisas till bifogade ritning, pà vilken FIG. lär en schematisk sidovy av en extruderlinje, FIG. 2 är till hälften en sidovy och till hälften en axialsektionsvy av kalibreringshylsan i en kalibrator av vakuumtyp, försedd med ultraljud- sensorer, och FIG. 3 är ett schema som visar anslutningen av sensorerna till extrudermunstyckets värmeelement via en mikroprocessor.For a more detailed explanation of the invention, reference is made to the accompanying drawing, in which FIG. teaches a schematic side view of an extruder line, FIG. 2 is half a side view and half an axial sectional view of the calibration sleeve of a vacuum type calibrator equipped with ultrasonic sensors, and FIG. 3 is a diagram showing the connection of the sensors to the heating element of the extruder nozzle via a microprocessor.

I FIG. 1 visas en extruderlinje för extrudering av rör i sin enklaste form. Extrudern är delvis visad vid 10, och frän dennas munstycke 10A (som utgör del av extruderverktyget) utpressas ett rör 11, som pas- serar genom en kalibrator 12 och sedan genom en kyl- ränna 13 till en avdragare 14. Vid det mät- och reg- lersystem som idag tillämpas och som beskrivits ovan, är ultraljudsonden placerad vid det ställe som är mar- kerat med en pil 15 i kylrännans utgàngsände.In FIG. 1 shows an extruder line for extruding pipes in their simplest form. The extruder is partially shown at 10, and from its nozzle 10A (which forms part of the extruder tool) a tube 11 is extruded, which passes through a calibrator 12 and then through a cooling chute 13 to a puller 14. At the measuring and control system that is currently applied and as described above, the ultrasonic probe is placed at the place marked with an arrow 15 in the exit end of the cooling gutter.

Vid tillämpning av sättet enligt uppfinningen an- vändes i ett utförande tre stationärt anordnade ultra- ljudsensorer, som är placerade inuti kalibratorn. I FIG. 2 visas kalibratorhylsan 16 till en kalibrator av vakuumtyp, och den är pä känt sätt utförd med ett an- tal genomgående slitsar 17, som förbinder hylsans in- sida med en hylsan omgivande vakuumkammare 18. Plast- röret 11 kommer frän extrudermunstycket och passerar 10 15 20 25 30 35 500 696 in i kalibratorhylsans vänstra ände, varvid det suges mot hylsans insida under inverkan av vakuumet för att kalibreras mot denna. I hylsans utgàngsände, den högra i figuren, skall vara anordnade tre ultraljudsensorer 19A, 19B och l9C, fördelade med 1200 mellanrum sásom visas schematiskt i FIG. 3, men i FIG. 2 är för enkel- hets skull visade endast tvà av sensorerna, nämligen 19A och 19B. Varje sensor är infäst i en hällare 20 pä en ring 21, som är fäst utanpá kalibratorhylsan 16, varvid frán sensorn är anordnad en passage 22 genom hàllaren. ringen och hylsan till det genom hylsan pas- serande röret, och denna passage hálles fylld med vat- ten, som tillföres vid en nippel 23 och tjänar som transmissionsmedium för ultraljudet mellan sensorn och röret.When applying the method according to the invention, in one embodiment three stationary ultrasonic sensors are used, which are placed inside the calibrator. In FIG. 2 shows the calibrator sleeve 16 of a vacuum type calibrator, and it is made in a known manner with a number of through-going slots 17, which connect the inside of the sleeve to a vacuum chamber 18 surrounding the sleeve 18. The plastic tube 11 comes from the extruder nozzle and passes Into the left end of the calibrator sleeve, sucking against the inside of the sleeve under the action of the vacuum to calibrate against it. At the output end of the sleeve, the one on the right in the figure, there shall be arranged three ultrasonic sensors 19A, 19B and 19C, distributed at 1200 intervals as shown schematically in FIG. 3, but in FIG. 2 is for simplicity shown only two of the sensors, namely 19A and 19B. Each sensor is mounted in a holder 20 on a ring 21, which is attached to the outside of the calibrator sleeve 16, a passage 22 through the holder being arranged from the sensor. the ring and the sleeve to the tube passing through the sleeve, and this passage is kept filled with water, which is supplied at a nipple 23 and serves as a transmission medium for the ultrasound between the sensor and the tube.

I FIG. 3 visas att de tre ultraljudsensorerna 19A, 19B och 19C är anslutna till en mikroprocessor 24, vilken över ett reglerdon 25 (se även FIG. 1) styr tre elektriska värmelement 26A, 26B och 26C, som är anordnade i extrudermunstycket 10A och sträcker sig vartdera över ungefär en tredjedel av munstyckets om- krets. De tre sensorerna är anordnade stationärt centralt i var sin av de sektorer av rörets omkrets. som motsvarar de tre värmelementen, och vardera sen- sorn är anordnad att via mikroprocessorn och regler- donet styra det motsvarande värmelementet.In FIG. 3 shows that the three ultrasonic sensors 19A, 19B and 19C are connected to a microprocessor 24, which controls over a control device 25 (see also FIG. 1) three electric heating elements 26A, 26B and 26C, which are arranged in the extruder nozzle 10A and each extend over about a third of the circumference of the nozzle. The three sensors are arranged stationary centrally in each of the sectors of the circumference of the tube. which corresponds to the three heating elements, and each sensor is arranged to control the corresponding heating element via the microprocessor and the control unit.

När extruderlinjen är i drift, mäter sàlunda varje sensor tjockleken hos röret ll pä det mot- svarande mätstället pà röret, och denna signal vidare- befordras till mikroprocessorn, där signalen jämföres med signaler, som representerar inprogramerade gräns- värden, varav ett representerar det nedre toleransvär- det för väggtjockleken hos röret och det andra repre- senterar det övre toleransvärdet eller företrädesvis ett värde pà väggtjockleken, vilket ligger närmare det 500 696 10 15 20 25 30 35 nedre toleransvärdet. Om signalen fràn sensorn ligger under resp. över det lägre resp. det övre gränsvärdet, lämnar mikroprocessorn en styrsignal till reglerdonet för det motsvarande värmelementet, för att dettas ef- fekt skall ökas resp. minskas, sä att ytfriktionen mellan materialet och munstyckskanalens vägg i den sektor av munstycket, som värmes av det ifrågavarande värmelementet, blir mindre med päföljd att väggtjock- leken hos röret ökas resp. minskas i denna sektor.Thus, when the extruder line is in operation, each sensor measures the thickness of the tube 11 at the corresponding measuring point on the tube, and this signal is forwarded to the microprocessor, where the signal is compared with signals representing programmed limits, one of which represents the lower the tolerance value for the wall thickness of the pipe and the other represents the upper tolerance value or preferably a value of the wall thickness, which is closer to the lower tolerance value 500 696 10 15 20 25 30 35. If the signal from the sensor is below resp. over the lower resp. the upper limit value, the microprocessor leaves a control signal to the control device for the corresponding heating element, in order for its power to be increased resp. is reduced, so that the surface friction between the material and the wall of the nozzle channel in the sector of the nozzle which is heated by the heating element in question becomes smaller with the consequence that the wall thickness of the pipe is increased resp. reduced in this sector.

Responsen i regleringen är snabb, eftersom avstàndet mellan sensor och värmeelement är förhållandevis litet.The response in the control is fast, because the distance between the sensor and the heating element is relatively small.

Tre sensorer har visat sig vara ett lämpligt an- tal för rör upp till 200 mm diameter, men för större rör kan ett större antal sensorer vara anordnade.Three sensors have proven to be a suitable number for pipes up to 200 mm in diameter, but for larger pipes a larger number of sensors can be provided.

I ett annat utförande av sättet enligt uppfinningen är sensorerna anordnade rörliga i omkretsled, varvid de föres fram och äter över den tillordnade sektorn av röret och det i mikroprocessorn beräknas ett medelvärde av de i sektorn uppmätta tjockleksvärdena. Medelvärdet användes sedan till reglering av det tillordnade värmeelementets effekt sàsom tidigare beskrivits.In another embodiment of the method according to the invention, the sensors are arranged circumferentially movable, whereby they are advanced and eaten over the assigned sector of the pipe and an average value of the thickness values measured in the sector is calculated in the microprocessor. The average value is then used to control the power of the assigned heating element as previously described.

Claims (4)

10 15 20 25 30 35 500 696 PATENTKRAV10 15 20 25 30 35 500 696 PATENT REQUIREMENTS 1. Sätt vid extrudering av plaströr (11) frän ett ex- trudermunstycke (10A) med ett antal värmeelement (26A, 26B, 26C), som är fördelade periferiellt omkring extru- dermunstycket, varvid det extruderade rörets väggtjocklek mätes medelst ultraljud pä ställen utmed rörets omkrets och effekten i värmeelementen regleras i beroende av upp- mätta tjockleksvärden i ett antal runt Omkretsen av röret fördelade mätpunkter (19A, 19B, l9C), som motsvarar anta- let värmeelement i extrudermunstycket för reglering av yt- friktionen och därmed väggtjockleken i de mot värmelemen- ten svarande sektorerna av rörväggen, k ä n n e t e c k - n a t av att mätningen av väggtjockleken sker pä kalibre- ringshylsan (16) i en i extruderlinjen ingàende vakuum- eller övertryckskalibrator (12).When extruding plastic tubes (11) from an extruder nozzle (10A) with a number of heating elements (26A, 26B, 26C) distributed circumferentially around the extruder nozzle, the wall thickness of the extruded tube is measured by ultrasound at locations along the circumference of the tube and the power in the heating elements are regulated depending on measured thickness values in a number of measuring points distributed around the circumference of the tube (19A, 19B, 19C), which corresponds to the number of heating elements in the extruder nozzle for regulating the surface friction and thus the wall thickness in the against the heating elements corresponding to the sectors of the pipe wall, characterized in that the measurement of the wall thickness takes place on the calibration sleeve (16) in a vacuum or overpressure calibrator (12) included in the extruder line. 2. Sätt enligt krav 1, mätningen sker vid kalibratorhylsans (12) utgängsände.Method according to claim 1, the measurement takes place at the outlet end of the calibrator sleeve (12). 3. Sätt enligt krav 1 eller 2, n a t av att mätningen sker i fasta mätpunkter.3. A method according to claim 1 or 2, unless the measurement takes place at fixed measuring points. 4. Sätt enligt krav 1 eller 2, av att mätpunkterna föres fram och äter i omkrets- k ä n n e t e k n a t av att k ä n n e t e c k - k ä n n e t e c k - n a t led över den sektor av röret. som motsvarar det tillordna- de värmeelementet, och att regleringen ästadkommes i be- roende av ett beräknat medelvärde av väggtjockleken inom sektorn.4. A method according to claim 1 or 2, in that the measuring points are advanced and eaten in the circumferential chain n e t e k n a t by the k n n e t e c k - k ä n n e t e c k - n a t led across that sector of the pipe. which corresponds to the assigned heating element, and that the regulation is achieved depending on a calculated average value of the wall thickness in the sector.
SE8900845A 1989-03-10 1989-03-10 Procedure for extrusion of plastic pipes SE500696C2 (en)

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SE8900845A SE500696C2 (en) 1989-03-10 1989-03-10 Procedure for extrusion of plastic pipes
PCT/SE1990/000154 WO1990010530A1 (en) 1989-03-10 1990-03-12 Method for extruding a plastic pipe

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DE9017848U1 (en) * 1989-10-31 1992-06-25 Inoex Gmbh Innovationen Und Ausruestungen Fuer Die Extrusionstechnik, 4970 Bad Oeynhausen, De
EP0537647A3 (en) * 1991-10-17 1993-08-18 Conpro Gmbh Extrusion installation with a wall thickness measuring apparatus for an extruded pipe
EP0573907B2 (en) * 1992-06-10 2000-06-28 CONPRO GmbH Extruder with wall thickness measuring device
US5686661A (en) * 1996-06-04 1997-11-11 Mississippi State University In-situ, real time viscosity measurement of molten materials with laser induced ultrasonics
AT413272B (en) * 2002-11-08 2006-01-15 Technoplast Kunststofftechnik DEVICE FOR COOLING AND CALIBRATING PLASTIC PROFILES
US9849619B2 (en) * 2010-11-11 2017-12-26 Toyo Seikan Kaisha, Ltd. Apparatus for correcting the bending of a molten resin and method of correcting the bending of the molten resin
CN108016020B (en) * 2017-12-12 2023-10-24 河北天昱恒科技有限公司 Automatic detection device for plastic pipe
DE102018113663A1 (en) * 2018-06-08 2019-12-12 Volkswagen Aktiengesellschaft Method for in-process measurement of process parameters and component properties in the production of hollow profiles and a measuring device therefor
CN115214107B (en) * 2022-07-22 2023-09-05 山东归仁新型材料科技有限公司 Sizing device for plastic pipe production

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US4137025A (en) * 1977-03-07 1979-01-30 Graves Kenneth E Apparatus for measuring and controlling the wall thickness of plastic pipes
NL8304451A (en) * 1983-12-27 1985-07-16 Wavin Bv METHOD AND APPARATUS FOR CONTROLLING THE WALL THICKNESS OF EXTRUDED PLASTIC TUBE.
US4740146A (en) * 1986-07-25 1988-04-26 Peter Angelbeck Apparatus for measuring and controlling the wall thickness of plastic pipes
US4882104A (en) * 1987-04-03 1989-11-21 Cincinnati Milacron, Inc. Method of controlling the thickness of an extruded plastic article

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