AU615676B2 - Installation for the treatment and direct transformation of thermoplastic waste into castings - Google Patents

Description

AU-AI-23838/88 6 1 5 2 i 6 GANISATION MONDALE DE LA PROPRIETE INTELLECTUELLE _fi T Bureau international DEMANDE INTERNATIONALE PUBLIEE EN VERTU DU TRAITE DE COOPERATION EN MATIERE DE BREVETS (PCT) (51) Classification internationale des brevets4 (11) NumBro de publication internationale: WO 89/ 02816 B29B 17/00, B29C 47/36, 47/44 Al (43) Date de publication internationale: 6 avril 1989 (06.04.89) (21) Numro de la demande internationale: PCT/BES8/00025 (81) Etats d6sign6s: AT (brevet europ6en), AU, BE (brevet europben), CH (brevet europ6en), DE (brevet euro- (22) Date de d6p6t international: peen), FR (brevet europeen), GB (brevet europ6en), 21 septembre 1988 (21.09.88) IT (brevet europ6en), KR, LU (brevet europ6en), NL (brevet europben), SE (brevet europben), US.

(31) Num6ro de la demande prioritaire: 8701069 Publiie (32) Date de priorit6: 23 septembre 1987 (23.09.87) Avec rapport de recherche internationale.

(33) Pays de priorit6: BE (71) D6posant (pour tous les Etats dsigns sauf US): AD- VANCED RECYCLING TECHNOLOGY LTD [CH/CH]; 9, rue Caroline, CH-1003 Lausanne (CH).

(72) Inventeur; et Inventeur/D6posant (US seulement) JULIEN, Philippe Q J. j U N 9 [BE/BE]; 323, avenue Moliere, B-1060 Bruxelles (BE).

(74) Mandataire: OVERATH, Philippe; Cabinet Bede, 13, AUSTRALIAN avenue Antoine Depage, B-1050 Bruxelles (BE).

18 APR 1989 PATENT OFFICE (54) Title: INSTALLATION FOR THE TREATMENT AND DIRECT TRANSFORMATION OF THERMOPLASTIC WASTE INTO CASTINGS (54) Titre: INSTALLATION DE TRAITEMENT ET DE TRANSFORMATION DIRECTE DE DECHETS THERMO- PLASTIQUES EN PIECES MOULEES sB (57) Abstract 75 92 S 36 50 49 14 The installation comprises an extruder (12) of which the extrusion screw (36) may be ax- 3 ially displaced, a number of moulds (14) ar- C _3 ranged horizontally in a molding loop of 0 which a plate (74) may be displaced on its 46 92 53 52 threaded axis thereby bringing the moulds a (14) into successive positions of filling, consolidation, cooling and mould removing. A material sensor (53) positioned at an adjustable distance s16 86 from the rear end of the mould (14) can stop the filling cycle, elastic means (88) being provided for the sealing of the mould (14) after its filling and a device (94, 96) receiving the casting after unmoulding.

(57) Abrige L'installation comporte une extrudeuse (12) dont la vis d'extrusion (36) peut etre d6plache axialement, un nombre de moules (14) disposes horizontalement dans un carrousel dont un plateau (74) peut 6tre diplac6 sur son axe filet (78), amenant les mouls (14) successivement en position de remplissage, de consolidation, de refroidissement et de d6moulage, un dtecteur (53) de matibre place a distance r6glable de l'extremit6 arridre du moule (14) pouvant arrater le cycle de remplissage, des moyens l61astiques (88) assurant I'tanch6it6 du moule (14) apris son remplissage et un dispositif (94, 96) r6ceptionnant la piece sur toute sa longueur aprbs dtmoulage.

VERIFIED TRANSLATION OF f, L i-

DESCRIPTION

ARRANGEMENT FOR THE PROCESSING AND DIRECT TRANSFORMATION OF THERMOPLASTIC WASTE INTO MOULDED PARTS The present invention relates to an arrangement for the processing and direct transformation of i !thermoplastic waste, sorted or not, into parts for the building industry, poured into moulds, the material i of which has the appearance of wood but which has a distinctly superior resistance, in which the finely ground waste, to which certain additives and pigments have possibly been added, is rendered homogeneous in a vertical screw mixer, then discharged into an intermediate bin, from where it passes through a magnetic-separation system before being conveyed by an endless screw into the hopper of a special adiabatic extruder which has a short and steep screw and which transforms the matter intd a plasticized homogeneous substance which it pushes into the moulds which are made from standard sections of hollow steel.

A first process, called "Reverzer", -featuring in a brochure of the Japanese company Mitsubishi Petrochemical, is made mention of in "Japan Plastic Age", Vol. 12 of February 1974, pages 43 to 52.

In that process, the waste, sorted or not, of thermoplastic material such as: polyethylene, polypropylene, polyvinyl chloride, or mixtures thereof, is finely ground, stored and partially dried by the heat released during grinding. It is then introduced into the "Reverzer" unit, which is composed of a melting unit comprising a hopper where the material is softened and a mixer having an endless screw where it is liquefied, before being injected under pressure into a closed mould. After cooling by spraying with water or air, the mould is opened and the part is removed. Its shape is, of course, dependent on the shape of the mould. In this manner, beams, profiles, etc. can be moulded.

In that process, high pressures are generated during the mixing and liquefaction operations. The apparatus and the moulds used must therefore be designed such that they withstand these pressures.

Dutch Patent Application No. 7704265, dated 7.3.1978, in the name of E. Klobbie, covers a second process which permits the utilization of apparatus and standard moulds which do not need to withstand high pressures. The material is retained in the extruder until, under the effect of the elevation in temperature resulting from the electrical heating, it is completely fluidized, and until the granules of special additives having a low vaporization temperature are completely gasified and they cause an increase in pressure, which facilitates the expansion of thrp Puid material within the entire mould, one extremity of which is connected to the extruder and the other is provided with a vent which permits the gas to escape.

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2 That process permits the utilization of any type of commercial extruder, adiabatic or not, from which are removed the components provided to resist high pressures (100 to 450kg/cm2), i.e. the screen and the extrusion nozzle. The extruder is therefore reduced to an S endless-screw conveyor, and the moulds can consist of simple tubes or standard profiles.

The granules of special additives must have a o° oo vaporization temperature lower than that reached in the SC extruder (between 150 and 270 0 The percentage thereof, relative to the total mass of the mixture, determined by ei.erience, oscillates between 0,4 and depending on

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the type of mixture of thermoplastic waste and the end products to be moulded. If a gas (nitrogen or air) is used, it is introduced into the extruder only when the thermoplastic material is completely liquefied.

That process can be used in respect of all unwashed thermoplastic waste containing up to a maximum of 25% of impurities, i.e. non-plastic material.

The object of the present invention is to overcome these disadvantages of known processes, being: cost of the arrangement and moulds which must withstand more or less high pressures, incomplete filling of these moulds by certain types of thermoplastic mixtures and for certain more elaborately shaped moulds, and this despite the use of gasifying agents.

According to the invention there is provided an arrangement for the processing and direct transformation 2a i i' i~ i i

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of thermoplastic waste into moulded parts, comprising: a hopper; a screw extruder, feeding fluidized plastic matter, provided with an extrusion screw having a conical extremity accommodated in a cylinder having a corresponding conical extremity, which screw can be displaced along its longitudinal axis within a hollow drive spindle, such that the annular passage between the conical extremity of the extrusion screw and the conical extremity of the cylinder generates the counter-pressure required so that the matter flows out via the discharge opening at the desired temperature; a series of moulds, open at two extremities, disposed horizontally in a rotary support, placed in a bin frame filled with water; a control device driving the rotary support, in automatic rotation, step-by-step, bringing a mould from the filling position to the consolidation position, then to various positions for cooling in water and finally to 20 the unmoulding position; a bridge which is movable relative to the bin frame, supporting four jacks; the first or central jack ensuring the tightness of the mould on the injection side when the filling operation is stopped, the second or support jack ensuring the tightness of the mould in its second position, i.e. consolidation, the third or cutting jack controlling a blade which accurately cuts the flow of 2r 57< 2b matter overflowing via the vent, the fourth or ejection jack removing the part from the mould after the last operation; whereby the bridge comprises a sensor, capable of detecting the outflow of matter via the vent from the mould and of stopping the injection cycle by triggering the following cycle, this sensor being displaceable on its support so as to change the distance between the sensor and the vent.

To this end, the extruder used is of the standard type, without screen or injection fittings, the mixture not requiring the addition of a gasifying additive, the 4 .moulds which are open at two extremities can be manufactured from simple tubes or standard profiles, the "injection pressure required being controllable by the axial displacement of the extrusion screw. Other characteristics of the invention feature in the claims of the present application. Described hereinafter is an exemplified embodiment with reference to the drawings: Figure lA shows a side view of the overall arrangement, and 20 Figure 1B shows the same unit in plan view, Figure 2 shows a cross-section of the extrusion-system unit, Figure 3 shows, diagrammatically, a mould in its rotary support in the injecting position, Figure 4 shows a side view of the movable bridge unit provided with its various jacks, Figure 4A shows the support and cutting jacks, 2c Figure 4B shows the central jack and the sensing device, Figure 4C shows the ejector jack, Figure 5 shows a cross-section of the rotary support and its various components as well as the set of clamps ensuring the tightness of the mould after filling, Figure 6 shows the receiving device for the moulded part after release from the mould, with details (Figures 6A to 6D).

The overall arrangement illustrated in Figures 1 and 2 comprises a hopper 10 feeding thermoplastic waste to an extruder 12 of the standard type, without screen or injection fittings, at the outlet of which the heated and homogeneous matter is taken, in liquid state, by an extruder screw 36, which can be controlled axially, to one of ten moulds 14, mounted horizontally in a rotary support 16, provided in i" 0 T bin frame 18, filled with water in enforced circulation, formed by two circular plates 74, 76 mounted on a horizontal and partially cogged shaft 78, driven by a device 20 which engages with the cogged periphery of the plate 76, a bridge 22, which straddles the movable bin frame 18 along the length of the vertical walls thereof, thus permitting the adjusting of the arrangement according to the length 'from 1 to 4 meters) of the moulds 14, a device 24 which is provided in the extension of the bin frame 18, facing the ejecting position, to receive the entire length of the parts stripped from the moulds, at the other extremity of the arrangement; a hydraulic unit 26 supplying the hydraulic motors of the extruder and an electric cabinet 28 [for] the various electric components.

The extruder 12, illustrated in detail in Figure 2, comprises an hydraulic motor 30 which drives an extrusion screw 36 through a box enclosing two half-couplings 32, 34, which extrusion screw is very short and steep and comprises three sections having different profiles intended to feed, compress and render the matter homogeneous, accommodated in a cylinder 38 which is heated externally by electrical resistors 39, and capable of sliding within its hollow drive spindle 40 under the action of a controlling or support screw 42 controlled by a cogged wheel 44 mounted on the motor-sided half-coupling 32, which positions the extrusion screw 36 in its cylinder 38 in order that the annular passage between the conical extremity 46 of the extrusion screw 36 and the conical nozzle 48, heated by an electrical resistor 51, is such that it generates the counter-pressure and the friction required so that the matter, heated for a shorter or longer time by the electrical resistors, is discharged via the discharge nozzle 50 at the desired temperature, depending on the matter itself and on the shape of the mould to be filled completely, the extrusion screw 36 functioning practically adiabatically.

Figure 3 illustrates diagrammatically a mould 14 in an upper filling position, provided with three collars 49, 51 and 61 adjusted and situated with precision in the circular holes provided for this purpose in the plates 74, 76 serving to support the mould 14 in a horizontal position in the rotary support 16.

The collar 61, of smaller diameter, is perforated in its centre by a vent 59 for the escape of gas during 25 filling of the mould 14 and at the end of casting of the matter.

A pneumatic jack 52 serves to ensure, during the entire filling stage, the complete tightness of the mould (14) on the side of the extrusion-screw 36 by applying under high pressure the collar 49 against the discharge nozzle 50 via the mould 14 and its collar 61.

The jack 52 pushes the collar 61 via a U-shaped head which does not cover the vent 59, which is dimensioned as a function of the dimensions and shapes of the mould 14 and of the type of matter in order to provide, within this mould 14, sufficient pressure to ensure its complete filling.

A leer 53, provided at the exit of the vent 59, detects the outflow of the matter and, when tilting, stops the filling cycle. permitting the triggering of the following cycle. The distance lever 53. vent 59 can he adjusted, so as to delay, more or less, the stopping of the filling cycle and thus to permit, if necessary, an increase of pressure in the mould 14, enabling its complete filling.

,j -r 4 The circular plate 74 is provided, on both sides of each circular seat in which are placed the collars 51, with a flexible device comprising two clamps 88 which can pivot about their axis and which serve to press the collar 49, via the mould 14 and its collar 51, against the support disc 75, thus ensuring the complete tightness of the mould 14 on the injection side, after stopping the filling procedure, otherwise the matter,,still hot and fluid at this stage, can partially be discharged out of the mould 14, under the pressure of gas or steam possibly still dissolved therein.

Figures 4, 4A, 48 and 4C illustrate in detail the bridge and its four pneumatic jacks.

A central jack 52, illustrated in Figure 48, ensuring the tightness of the mould 14 when being filled, is provided with a sensor device in respect of'the outflow of the matter via the vent 59, the device comprising a sensor lever 53, which is adjustable on its axis 54 and which, when tilting, triggers a switch 56 which stops the filling .operation.

A support jack 58, illustrated in Figure 4A, ensures the tightness of the mould 14 after the filling operation by pushing the collar 49 against the support disc 75 via the mould 14 and its collar 51. This device comprises a second jack 60 controlling a blade 62 which automatically cuts, at the level of the collar 61, the matter which has flowed through the vent 59 upon completion of the filling of the mould 14.

The cut by jack 60 is effected, for example;in the second injection position, thus permitting a period of stabilization of the previously moulded part. The matter is therefore no longer active and, furthermore, the cu-ting device can be controlled precisely to cut the moulded part, in a non-moving position.

An ejector jack 64, illustrated in Figure 4C, comprises a blowing head 66 provided with a seal 68, into which the compressed air is directed via a duct 70, at an adjustable pressure and duration, in order to eject, after the last operation, the moulded part having gradually contracted by cooling in the water of the bin frame 18.

The mould-carrying rotary supp.:rt 16, illustrated in Figure 5, comprises two circular plates 74, 76' mounted on a horizontal shaft 78, in the shaft of the bin frame 18 supported at each extremity by a spherical bearing 80 which take up the radial loads (mass and driving torque) and the a.xial loads (thrust 'of the moulds against the support disc 75), the plate 76 cogged about its periphery, permitting rotation of the rotary support under the action of the driving device 20, the other plate 74, displaceable on the threaded section of its support shaft 78 provided with a thread, after release by rotation of the locking screw 86, permits the adjustment of the arrangement to the length of the ten moulds 14, the clamps 88 (see Figure 38) mounted on both sides of each peripneral seat of the plate 74, ensuring the complete tightness between the collar 49 of the mould 14 and the support disc 75, the pressure which they exert being adjustable in three ways: by progressive tightening of the screw 90, by increasing the number of sprino washers 92, or by means of the use of another type of spring washer 92.

Figures 6A, 68, 6C and 6D illustrate in detail the receiving device for the part after removal from the mould. It comprises a rectangular tube 94 having a base 96 which tilts under the effec; of a jack 104.

/T When the part is pneumatically expelled from its mould, it slides on to the bottom 96 and possibly runs T into the buffer 98 mounted at the extremity of the rectangular tube 94. On its way, it cuts the beam of the photoelectric cell 100, 102 which triggers the following cycle after the passage of the extruded item.

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Claims (5)

1. 2. Arrangement according to claim i, characterized in that the extruder screw is a short one which is displaceable within its hollow drive cylinder by the action of a support screw controlled by a cogged wheel.
2. 3. Arrangement according to claim i, characterized in S.that the rotary support comprises a circular plate which is displaceable on its shaft which is provided with S. thread, after release, by rotation, of a locking screw.
3. 4. Arrangement according to claim i, characterized in that each collar, as a rule welded to each mould, is Ssubjected, during the entire rotation of the rotary support, to the pressure of a flexible means composed of two clamps, which can pivot about their axis, composed of a pressure-regulating screw and a set of a varying number of spring washers. Arrangement according to claim i, characterized in ru II C .f 8 that it comprises a device for unmoulding by the blowing of compressed air, comprising a jack composed of a blowing head provided with a seal and a duct.
4. 6. Arrangement according to claim 1, characterized in that it comprises a device for receiving, after removal from the mould, of the part over its entire length, composed of a rectangular tube having a tilting bottom, controlled by a jack, provided with a buffer and a photoelectric cell which detects the passage of an extruded item.
5. 7. An arrangement for the processing and direct transformation of thermoplastic waste into moulded parts substantially as herein described with reference to the accompanying drawings. DATED this ADVANCED RECYCLING TECHNOLOGY LIMITED Attorney: LEON K. ALLEN Eellow Institute of Patent Attorneys of Australia of SHELSTON WATERS