FI68016C - ANORDNING FOER TILLVERKNING AV STRAENGSPRUTADE PRODUKTER - Google Patents

Description

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B 29 C M / Ok, hl / 88, (51) Kv.lk.4 / lnc.Cl.4 H 0, g, 3 /! 4 gUQ | ^ || FINLAND (21) Patent application - Patentansökning 790737 (22) Application date - Ansöknlngjdag 05-03.79 (En) (23) Start date - Giltighetsdag 05.03.79 (41) Has become public - Blivit offentlig 08.09 79

National Board of Patents and Registration Date of display and publication— «

Patent- och registerstyrelsen '' Ansökan utlagd och utl.skriften publicerad 29.U3 .o5 (32) (33) (31) Privilege requested - Begärd priority 07.03.78 17.10.78 Sweden-Svenqe (SE) 78025 ^ 7-5, 7810792-7 (71) ASEA Aktiebolag, S-721 83 Vasteräs, Sweden-Sweden (SE) (72) Gustaf Linderoth, Bromma, Karl-Gunnar Wiberg, Stockholm, Sweden-Sweden (SE)

Ok) Berggren Oy Ab (5A) Equipment for the production of extruded products -Anordning för tillverkning av strängsprutade produkter

When manufacturing extruded products from a polymeric material, it is important to be able to interrupt the ongoing process or change the manufacturing conditions as soon as possible if the quality of the manufactured product becomes unsatisfactory. This avoids scrapping the prepared material as far as possible.

If the product is, for example, a high-voltage cable in which the conductor is surrounded by an inner conductive layer (inner semiconductor), the interface between the inner conductive layer and the insulation may, in unfavorable cases, have defects consisting of e.g. tips or stripes or prematurely vulcanized hard particles. Since such defects increase the electrical load on the layer and adversely affect the quality of the cable, it is important that the application of the polymeric material as insulation to the cable on said layer is stopped as soon as such defects occur or that the inner conductive layer is fixed. The inner conductive layer is normally applied by extrusion, after which the insulation is extruded. In addition, an outer conductive layer (outer semiconductor) is placed on top of the insulation. The attachment of the outer conductive layer, which, like the inner conductive layer, normally consists of a polymeric material containing 268Q1 6 conductive type carbon black and is therefore opaque, is often effected by extruding the layer onto the insulation after the insulation has been extruded.

If the raw materials for the conductive layers and insulation are crosslinkable, these materials can be simultaneously crosslinked by heating the conductor with its conductive layers and insulation under pressure in the vulcanization tube. If the substances are not crosslinkable, the conductors with the substances attached to them will end up directly in the cooling device. If the outer conductive layer is extruded onto the insulation immediately after it is formed, i.e., without conducting the conductor and insulation through the devices to crosslink or cool the insulation, defects in the inner conductive layer cannot be detected until the cable is complete. In contrast, the present invention allows continuous monitoring during ongoing fabrication to monitor the quality of the inner conductive layer as well as defects in blisters and contaminants in the cable insulation, provided the insulation material is transparent at the temperature at which the material is extruded, as is known in several known and in frequently used cabinet liners. Based on the findings of the inspection, the manufacturing process can be interrupted or corrected as necessary.

Crucial to the present invention when applied to the cable manufacturing described above is that the extrusion machine used to form the insulation and the extruder used to form the outer conductive layer are connected to each other by a connector having an inner wall adapted to abut the insulation during and / or for quality control of the insulation itself. The connecting piece, which may be cylindrical or conical on the inside or partly cylindrical and partly conical, has a smallest diameter on the inside equal to the outer diameter of the insulation. Thanks to this structure, the fitting performs other important tasks in addition to enabling quality control. One function that is important in the manufacture of cables with crosslinked insulation is that the connector, despite the pressure applied to the polymeric material in the connector, ensures that the insulation retains its dimensions. Another function, which is important both in the manufacture of 3 68016 cables with crosslinked insulation and in the manufacture of cables without crosslinked insulation, is that the connector acts as a conductor and insulation guide so that the outer conductive layer can be placed on top of the insulation as a flat layer immediately after insulation is formed. This can lead to significant savings in the space required by the manufacturing equipment. In special circumstances, the additional function of the fitting may be to act as a vulcanization tube.

The invention is useful and offers similar advantages in the manufacture of pipes, hoses and other profiles in which a transparent polymeric material is extruded during molding and then an opaque polymeric material is extruded onto the first polymeric material.

The type of device which is the subject of the invention, as well as the features of the invention, will become apparent from the appended independent claim 1, and some preferred embodiments are defined in claims 2 and 3.

For example, it is known from GB-1 359 507 to use two extruders with intermediate fittings. However, the connecting piece does not rest on the compressed material and does not allow the properties or appearance of the material to be checked.

The object of the present invention is, on the one hand, to be able to observe the properties of the extruded material well and, on the other hand, to make the connecting piece act to guide the material and to ensure its dimensions. These objects cannot be achieved by the arrangement according to said patent.

Examples of suitable raw materials for the transparent core at the molding temperature include polyethylene and a copolymer of ethylene and other unsaturated monomers such as ethyl acrylate, butyl acrylate and vinyl acetate. In the copolymer, the weight of ethylene is preferably at least 60% of the total weight of ethylene and other unsaturated compound. The polymeric material can be used without the addition of a crosslinking agent. In this case, the insulation acquires thermoplastic properties. Alternatively, a peroxide or other substance capable of causing crosslinking may have been added to the polymeric material. Examples of suitable peroxides are e.g. mention di-α-cumyl peroxide, di-tert-butyl peroxide and 2,5-dimethyl-4,601,6 2,5-di (t-butylperoxy) -hexine-3. The amount of peroxide is suitably 0.1 to 5 parts by weight / 100 parts by weight of the polymeric material. An antioxidant, e.g., polymerized trimethyldihydroquinoline or aldon-α-naphthylamine, is also normally added to the polymeric material, suitably in an amount of 0.5 to 5 parts by weight / 100 parts by weight of the polymer.

If the opaque layer is an electrically conductive layer, i.e. if the device is used for the production of high-voltage cables, the polymer material of the layer can be e.g. be chlorosulfonated polyethylene containing mineral oil as a plasticizer, a conductive type of carbon black and optionally a powdered filler such as talc, further copolymers of ethylene and vinyl acetate containing carbon black and optionally a powdered filler such as talc or chalk. If the layer is crosslinked, peroxide, which may be e.g. of the above-mentioned species, is additionally added in the above-mentioned amount.

If the opaque layer is a protective layer of a pipe, hose or other profile, such as a sheath that protects against the effects of UV radiation, it can e.g. consist of a polymeric material containing a few percent carbon black. The type of polymeric material can then be very variable. Suitable substances include e.g. polyethylene, polypropylene, polyvinyl chloride, chlorosulfonated polyethylene, chloroprene, nitrile rubber, polyamide and polyurethane. If the layer is crosslinked, e.g. the same type of peroxide as mentioned above for the polymeric material of the inner part and in the same amount is added.

The material of the transparent part of the connecting piece can be, for example, glass or quartz.

The invention will be explained in more detail by means of exemplary embodiments with reference to the accompanying drawing, in which Fig. 1 shows an apparatus for manufacturing a high voltage cable according to the invention, Fig. 2 shows an apparatus for manufacturing a tube with a UV shield and Fig. 3 shows an apparatus for manufacturing a high voltage cable.

In the figures, the extruder used for forming the inner part is denoted by the number 1, the extruder used for forming the opaque layer by the number 2 and the number 3 denotes 5 6801 6 fittings with a transparent part for controlling the product with the inner part. In the devices according to Figures 1 and 2, both the connecting piece 3 and the extrusion machine 2 are located in such a way that the extruded material in the extruding machine 1 is not crosslinked and has not undergone any other treatment as it passes the connecting piece and enters the extruding machine. in the extrusion machine 1, the extruded material is crosslinked when it enters the extrusion machine 2. In the examples shown in Figs. 1 and 2, the connecting piece consists of a cylindrical glass tube with a width of about 5 cm and an inner diameter equal to the outer diameter of the inner product. In the cases shown, the connecting piece is completely transparent.

According to Figure 1, a cable conductor 4, which is of the conventional type and may be copper or aluminum, is passed through the extrusion machines 1 and 2. Upon entering the extrusion machine 1, it is provided with an extruded inner conductive layer 5. This layer consists, by way of example, of a copolymer of ethylene and ethyl acrylate (weight ratio 80:20) containing 40 parts by weight of conductive carbon black and 2 parts by weight of di-t-butyl peroxide. parts per copolymer. The inner conductive layer can be e.g. also use those materials mentioned above as examples of outer conductive layer materials. The cable insulation 6 is fixed in the extrusion machine 1. In the exemplary case, it consists of LD polyethylene having a melt index of 0.2 to 20 and containing 2 parts by weight of di-α-cumyl peroxide and 0.2 parts by weight of polymerized trimethyldihydroquinoline per 100 parts by weight of polyethylene. towards. The temperature of the polyethylene during extrusion is 125 ° C. In the extruder 2, an outer conductive layer 7 is attached, which in the exemplary case consists of a copolymer of ethylene and vinyl acetate (weight ratio 60:40) containing 30 parts by weight of conductive carbon black and 2 parts by weight of di-butyl peroxide per 100 parts by weight of polymer. The cable conductor 4 with its layers 5, 6 and 7 then only enters the partially shown vulcanization tube 8, where the layers 5, 6 and 7 are crosslinked by heating them to about 220 ° C while applying a pressure of 1 MPa. As the polyethylene passes through the glass tube 3, its temperature is 125 ° C, as stated above, and it is then transparent. The quality of the inner conductive layer 5 and the insulation 6 can therefore be continuously monitored and the production can be interrupted or the manufacturing conditions can be adjusted if it turns out that defects occur in the inner conductive layer or in the insulation itself.

Figure 2 shows an apparatus for manufacturing a tube provided with a protective layer against UV radiation. In this figure, the mandrel 9 extends through the extruders 1 and 2. In the extruder 1, the extrudable tube 10 is HD polyethylene having a melt index of 0.1 and containing 0.2 parts by weight of polymerized trimethylhydroquinoline / 100 parts by weight of polyethylene. The temperature of the polyethylene during extrusion is 240 ° C. In the extrusion machine 2, a protective layer 11 is attached, which is HD polyethylene containing 3 parts by weight of carbon black and 0.2 parts by weight of polymerized trimethylhydroquinoline per 100 parts by weight of polyethylene. After molding, the tube consisting of layers 10 and 11 is immersed in a water bath (not shown) at a temperature of almost 100 ° C, where the tube is cooled. The temperature of the polyethylene 10 as it passes through the glass tube 3 is, as can be seen from the above, 240 ° C, whereby it is transparent. Thus, the quality of the layer 10 can be continuously monitored and the necessary changes made to the manufacturing process.

In the devices according to Figures 1 and 2, the connecting piece 3 can also be conical or consist of a conical and cylindrical part. It then has a smallest inner diameter which is the same as the outer diameter of the inner part 6 and 10 of the product to be manufactured, respectively. The joint body can, of course, consist of a larger or smaller part of metal and a partially transparent part. The connecting piece can, for example, consist of a cylindrical or conical metal tube in which a glass window is embedded.

According to Figure 3, the connecting piece 3 between the extruders 1 and 2 is a glass tube which also acts as a vulcanization tube. The vulcanization tube is surrounded by a radiation source 12 consisting of a plurality of infrared lamps arranged around the tube with tungsten filaments operating at a temperature of 2100 ° C, thereby emitting radiation having a maximum intensity at a wavelength of 1.2 μm. In the extrusion machine 1, the conductor is first provided with an inner conductive layer 5 and an insulation 6 thereon. The materials of the layers 5 and 6 may be the same as those shown for the respective layers in the manufacture of the high-voltage cable described in connection with Fig. 1. The temperature of the polyethylene of layer 6 7 6801 6 is about 125 ° C during extrusion. When the conductor 4 with its layers 5 and 6 passes the radiation source 12, the polymers of the layers 5 and 6 are then crosslinked and cooled with water or gas under pressure in a cooling tube (not shown) connected to the left end of the vulcanization tube 3. The polymers are subjected to pressure in the vulcanization tube. The pressure is provided by taking advantage of the thermal expansion of the polymer together with the pressure from the nozzle of the extruder 1 at one end of the vulcanization tube and the pressure of the coolant at the other end of the vulcanization tube. Because the vulcanization tube and polyethylene in the molding heat pass short-wave infrared radiation, rapid heating of the cable conductor and inner conductive layer occurs, resulting in rapid overheating and rapid crosslinking of the polymer across the entire cross section. The outer conductive layer 7 to be attached in the extruder 2 may be formed of a copolymer of ethylene and vinyl acetate (weight ratio 60:40) containing 20 parts by weight of a conductive type carbon black / 100 parts by weight of a copolymer. If the layer is to be crosslinked, peroxide must be added and heated in a device arranged after the extruder 2 and before the cooling device in the direction of the cable. Since the vulcanization tube is transparent as well as the insulation 6 when it is located in the vulcanization tube, the quality of the inner conductive layer 5 and the insulation 6 can be continuously monitored and production can be changed or its conditions changed if defects prove to occur in either layer.

Claims (5)

6801 6 8 Extract suction t Apparatus for producing extruded products from a polymeric material and comprising an extrusion machine (1) for molding a transparent inner part (6, 10) into a product at the molding temperature, e.g. insulation (6) with a conductor (4) (inner semiconductor) cable conductor (4) and an extrusion machine (2) for forming an opaque layer (7, 11) surrounding the inner part, e.g. an electrically conductive layer (7) (outer semiconductor) on the cable insulation (6), the extruder used for forming the inner part and is connected to each other by a connecting piece (3), characterized in that the inner wall of the connecting piece (3) is adapted to abut the transparent inner part during this extrusion and the connecting piece is transparent or has a transparent part for quality control of the product interior and / or interior parts. Device according to Claim 1, characterized in that the connecting piece (3) is a cylindrical or conical transparent tube. Device according to Claim 1 or 2, characterized in that the connecting piece (3) acts as a vulcanization tube for the transparent part (6, 10). 1. An arrangement for the production of a product of a polymeric material in a polymeric material (1) for the production of a product of the genomic internal structure (6, 10) and a product, i.e. an isolation (6) for an electrically insulated device (5) (in the case of low voltage) for cable cabling (4), and in the case of power supply (2) for the formation of the internal power supply (7, 11), i.e. for the electrical connection (7) (for low voltage) in the cable insulation ( 6), varvid strangsprutningsmaskinen för formning av innerdelen och strängsprutningsmaskinen för formning av det ogenomsynliga skiktet. is used for a variety of products (3),