WO1990002038A1 - Method and device for joining together of tubular plastic products - Google Patents

Method and device for joining together of tubular plastic products Download PDF

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Publication number
WO1990002038A1
WO1990002038A1 PCT/FI1989/000153 FI8900153W WO9002038A1 WO 1990002038 A1 WO1990002038 A1 WO 1990002038A1 FI 8900153 W FI8900153 W FI 8900153W WO 9002038 A1 WO9002038 A1 WO 9002038A1
Authority
WO
WIPO (PCT)
Prior art keywords
mould tool
joint
heating
plastic products
plastic
Prior art date
Application number
PCT/FI1989/000153
Other languages
French (fr)
Inventor
Ralf Stoor
Original Assignee
Oy Muotekno Ab
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=25673145&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=WO1990002038(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Priority to FI883885A priority Critical patent/FI82635C/en
Application filed by Oy Muotekno Ab filed Critical Oy Muotekno Ab
Priority to DE68914996T priority patent/DE68914996T3/en
Priority to AT8989909397T priority patent/ATE104901T1/en
Priority to EP89909397A priority patent/EP0431000B2/en
Priority to CA000614466A priority patent/CA1333653C/en
Publication of WO1990002038A1 publication Critical patent/WO1990002038A1/en
Priority to NO91910613A priority patent/NO910613L/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
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14467—Joining articles or parts of a single 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
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14336—Coating a portion of the article, e.g. the edge of the 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
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B29C45/14598—Coating tubular articles
    • B29C45/14614—Joining tubular articles
    • 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
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/70—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by moulding
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/05—Particular design of joint configurations
    • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
    • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
    • B29C66/114—Single butt joints
    • B29C66/1142—Single butt to butt joints
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
    • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
    • B29C66/52—Joining tubular articles, bars or profiled elements
    • B29C66/522—Joining tubular articles
    • B29C66/5221—Joining tubular articles for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • B29C66/7232—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer
    • B29C66/72321—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a non-plastics layer consisting of metals or their alloys
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L13/00—Non-disconnectible pipe-joints, e.g. soldered, adhesive or caulked joints
    • F16L13/02—Welded joints
    • F16L13/0254—Welded joints the pipes having an internal or external coating
    • F16L13/0272—Welded joints the pipes having an internal or external coating having an external coating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
    • F16L58/18—Protection of pipes or pipe fittings against corrosion or incrustation specially adapted for pipe fittings
    • F16L58/181—Protection of pipes or pipe fittings against corrosion or incrustation specially adapted for pipe fittings for non-disconnectible pipe joints
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L59/00—Thermal insulation in general
    • F16L59/14—Arrangements for the insulation of pipes or pipe systems
    • F16L59/16—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like
    • F16L59/18—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for joints
    • F16L59/20—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for joints for non-disconnectable joints
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/01—General aspects dealing with the joint area or with the area to be joined
    • B29C66/02—Preparation of the material, in the area to be joined, prior to joining or welding
    • B29C66/024—Thermal pre-treatments
    • B29C66/0242—Heating, or preheating, e.g. drying
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
    • B29C66/723—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered
    • B29C66/7234—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a barrier layer
    • B29C66/72343—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined being multi-layered comprising a barrier layer for liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/22—Tubes or pipes, i.e. rigid
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49826—Assembling or joining
    • Y10T29/49888—Subsequently coating

Definitions

  • the present invention concerns a method and a device for joining together of tubular plastic products by fitting and fixing these in the desired position on the support of an inner tube or a provisional support sleeve, by heating the joint faces of the plastic products, which have been chamfered at least partly in advance, to the melting point of the plastic material, and by passing molten plastic material into the space that is formed on the fitting together between the opposite joint faces.
  • Prior-art methods of this type are based on the so-called extruder weld principle, according to which a strand of molten plastic material from an extruder nozzle is gradual ⁇ ly fed into a groove of preferably V-section, which is formed between the tubular plastic products to be joined together.
  • the extruder nozzle must be passed along the groove substantially at the same speed as the strand of plastic mix is pressed out of the extruder nozzle.
  • complete synchronization must prevail between the feeding velocity of the plastic mix and the extruder nozzle.
  • the extruder may be either shaped as a hand tool, in which case high professional skill is required, or it may be mounted on a welding machine, wherein the feeding of the plastic mix and the drive of the tubular plastic product or of the extruder nozzle take place completely automatically. It is a drawback of extruder welding that it is very slow and requires relatively complicated equipment if the work is to be carried out as mechanized.
  • the protective and insulating layer comprises an inner foamed plastic mate ⁇ rial, such as foamed polyolefin or equivalent, and an outer protective mantle of a smooth and liquid-tight plastic, likewise polyolefin or some other weldable plastic.
  • the pipeline is prefabricated in certain lengths with just a little portion at each end free from the surrounding pro ⁇ tective and insulating layer to permit welding together of the metal pipes.
  • the platform on which the work is performed is driven forwards along the length of the pipeline piece, whereby the newly welded joint arrives at the station at which the joint is to be provided with a protective and insulating layer similar to that surrounding the rest of the pipeline.
  • a protective and insulating layer similar to that surrounding the rest of the pipeline.
  • the object of the present invention is to eliminate all of the above problems, which is accomplished by means of a method that is characterized in that the fixing of the tubular plastic products and the feed of the molten plastic material take place with the aid of a mould tool which is applied onto the space between the plastic products that are to be joined together, and the molten plastic material is passed rapidly under pressure into the hollow space between the mould tool and the joint faces through a feed stub provided in the mould tool, whereupon the plastic material is cooled and the mould tool and an inner support bushing, if any, are removed.
  • Fig. 1 shows an exemplifying embodiment of a tubular plastic product which is suitable for the present invention
  • Fig. 2 shows an exemplifying embodiment of a device in accordance with the invention that is suitable for joining together of the plastic product of Fig. 1,
  • Fig. 3 shows a plastic product joined together by means of the device shown in Fig. 2, and
  • Fig. 4 shows another example of joining together in accordance with the invention.
  • the function of the mould tool 5 is to fix the tubular plastic products 1 , 2 to be joined together, on one hand, and to enclose the grooves 4 tightly and to form a mould for the molten plastic material that is, upon completed heating of the joint faces, rapidly injected into the V-section grooves 4 through at least one feed stub 6 provided on the mould tool 5, on the other hand.
  • the cooling is started, e.g., by means of cold air.
  • some more plastic mix is still pressed into the hollow space in order to prevent formation of cavities in the seam 7 that is formed.
  • the mould tool 5 and the inner, preferably collapsible support bushing, if the latter has been used during the process of joining together, are removed.
  • the mould tool 5 is provided with an inner mould face of substantially concavely circular arcuate section, which determines the outer contour of the seam 7 to be formed.
  • the feed stub 6 in the mould tool should be placed as centrally as possible in relation to the end portions of the mould tool 5 so that the molten plastic mix reaches the portions of the hollow space between the joint faces and the mould tool 5 that are most distant from the feed stub 6 approximately at the same time.
  • the molten plastic mix is passed to the feed stub 6, e.g., through a supply pipe (not shown) .
  • one or more control openings are provided, through which molten plastic material is supposed to be extruded as an indication to the effect that the hollow space between the mould tool 5 and the joint faces is full.
  • the heating of the joint faces may take place in a number of different ways, either before or after the mould tool 5 is applied. If the heating takes place before the mould tool is applied, it can be carried out, e.g., by means of a tightly fitting heating tool, which is either heated in advance or is provided with heating members and which is placed into the V-section groove 4 between the joint faces during the heating stage. After the joint faces have reached their melting temperature, the heating tool is removed and the mould tool 5 is applied.
  • the heating may take place either by means of a heated gaseous medium, which is injected into the hollow space between the mould tool 5 and the joint faces through the feed stub 6 or through a separate connection, or by means of radiation heat from a resistor wire in the mould tool.
  • the mould tool 5 has preferably a substantially U-shaped cross-section, and it is provided with a transverse articu ⁇ lated joint 8 for closing and opening of the mould tool 5. If the mould tool is supposed to be used for joining together of two tube ends, it has an annular shape and the feed stub 6 is fitted at the proximity of the trans ⁇ verse articulated joint 8.
  • the mould tool is shaped as a flexible metal band, whose ends are provided with locking members for locking of the mould tool in the working position around the tubular plastic products to be joined together.
  • the mould tool 5 When the mould tool is intended for joining together of a split-open joint piece 2 between the protective and insulating layers 1 on two metal pipes 3 welded together in a pipeline for offshore, district-heating, or similar use, the mould tool 5 comprises two parallel portions 5a, which are supposed to enclose peripheral grooves 4 of their own, and one transverse portion 5b fitted between them for an axially directed groove 4.
  • the connection stub 6 is appropriately fitted at the middle point of the transverse portion 5b.
  • the trans- verse portion 5b is appropriately telescopic.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Abstract

The present invention concerns a method and a device for joining together of tubular plastic products (1, 2) by heating the joint faces of the plastic products (1, 2), which have been chamfered at least partly in advance, and by passing molten plastic material into the space (4) that is formed between the opposite joint faces. The invention is characterized in that the fixing of the tubular plastic products (1, 2) and the feed of the molten plastic material take place with the aid of a mould tool (5) which is applied onto the space (4), and molten plastic material is passed rapidly into the hollow space between the mould tool (5) and the joint faces through a feed stub (6) provided in the mould tool.

Description

Method and device for joining together of tubular plastic products
The present invention concerns a method and a device for joining together of tubular plastic products by fitting and fixing these in the desired position on the support of an inner tube or a provisional support sleeve, by heating the joint faces of the plastic products, which have been chamfered at least partly in advance, to the melting point of the plastic material, and by passing molten plastic material into the space that is formed on the fitting together between the opposite joint faces.
Prior-art methods of this type are based on the so-called extruder weld principle, according to which a strand of molten plastic material from an extruder nozzle is gradual¬ ly fed into a groove of preferably V-section, which is formed between the tubular plastic products to be joined together. During the welding the extruder nozzle must be passed along the groove substantially at the same speed as the strand of plastic mix is pressed out of the extruder nozzle. In order that a tight and reliable joint could be obtained, complete synchronization must prevail between the feeding velocity of the plastic mix and the extruder nozzle. The extruder may be either shaped as a hand tool, in which case high professional skill is required, or it may be mounted on a welding machine, wherein the feeding of the plastic mix and the drive of the tubular plastic product or of the extruder nozzle take place completely automatically. It is a drawback of extruder welding that it is very slow and requires relatively complicated equipment if the work is to be carried out as mechanized.
In particular in the case of installation of insulated offshore pipelines which comprise an inner metal pipe for transfer of medium and a coextruded protective and insulating layer of plastic surrounding the metal pipe, it is required that the welding of the protective and insulating layer must not take a longer time than the welding together of two metal pipes. The protective and insulating layer comprises an inner foamed plastic mate¬ rial, such as foamed polyolefin or equivalent, and an outer protective mantle of a smooth and liquid-tight plastic, likewise polyolefin or some other weldable plastic. The pipeline is prefabricated in certain lengths with just a little portion at each end free from the surrounding pro¬ tective and insulating layer to permit welding together of the metal pipes. On completion of the welding, the platform on which the work is performed is driven forwards along the length of the pipeline piece, whereby the newly welded joint arrives at the station at which the joint is to be provided with a protective and insulating layer similar to that surrounding the rest of the pipeline. For this purpose it is possible to utilize prefabricated cylindrical, axially split-open joint pieces with chamfered edges, which joint pieces must be fixed by welding with absolutely liquid-tight seams, two peripheral circular seams along the ends of the joint piece and one axial straight seam along the split slot of the joint piece.
With extruder welding there is no chance to attain a welding speed that is required to keep pace with the metal pipe welding.
The object of the present invention is to eliminate all of the above problems, which is accomplished by means of a method that is characterized in that the fixing of the tubular plastic products and the feed of the molten plastic material take place with the aid of a mould tool which is applied onto the space between the plastic products that are to be joined together, and the molten plastic material is passed rapidly under pressure into the hollow space between the mould tool and the joint faces through a feed stub provided in the mould tool, whereupon the plastic material is cooled and the mould tool and an inner support bushing, if any, are removed.
Further characteristics of the invention come out from the accompanying patent claims 1 to 13.
In the following, the invention will be described in more detail with reference to the accompanying drawing, wherein
Fig. 1 shows an exemplifying embodiment of a tubular plastic product which is suitable for the present invention,
Fig. 2 shows an exemplifying embodiment of a device in accordance with the invention that is suitable for joining together of the plastic product of Fig. 1,
Fig. 3 shows a plastic product joined together by means of the device shown in Fig. 2, and
Fig. 4 shows another example of joining together in accordance with the invention.
When tubular plastic products, such as plastic tubes, split-open joint pieces 2 on joints in the case of metal pipes 3 provided with protective and insulating layers 1 , or possibly tube halves, are joined together, according to the present invention, first the plastic products 1 , 2 are fitted and fixed in the desired position supported by an inner pipe 3 or by a provisional support bushing after all of the joint faces have been worked, i.e. chamfered so that a groove 4 of substantially V-section is formed for each seam, as comes out, e.g., from Fig. 1. Thereupon the chamfered joint faces are heated to the melting point of the plastic material in a suitable way either before or after a mould tool 5 is applied onto the V-section grooves 4. The function of the mould tool 5 is to fix the tubular plastic products 1 , 2 to be joined together, on one hand, and to enclose the grooves 4 tightly and to form a mould for the molten plastic material that is, upon completed heating of the joint faces, rapidly injected into the V-section grooves 4 through at least one feed stub 6 provided on the mould tool 5, on the other hand.
As soon as the entire hollow space 4 is filled with plastic mix, the cooling is started, e.g., by means of cold air. During the initial stage of the cooling, some more plastic mix is still pressed into the hollow space in order to prevent formation of cavities in the seam 7 that is formed. After the surface of the plastic mix in the seam 7 formed has solidified, the mould tool 5 and the inner, preferably collapsible support bushing, if the latter has been used during the process of joining together, are removed. By means of this method, a uniform and high-quality seam 7 is obtained extremely rapidly and simply.
The mould tool 5 is provided with an inner mould face of substantially concavely circular arcuate section, which determines the outer contour of the seam 7 to be formed. The feed stub 6 in the mould tool should be placed as centrally as possible in relation to the end portions of the mould tool 5 so that the molten plastic mix reaches the portions of the hollow space between the joint faces and the mould tool 5 that are most distant from the feed stub 6 approximately at the same time. The molten plastic mix is passed to the feed stub 6, e.g., through a supply pipe (not shown) . At the point or points of the mould tool 5 that is/are placed most distant from the feed stub 6, one or more control openings (not shown) are provided, through which molten plastic material is supposed to be extruded as an indication to the effect that the hollow space between the mould tool 5 and the joint faces is full.
The heating of the joint faces may take place in a number of different ways, either before or after the mould tool 5 is applied. If the heating takes place before the mould tool is applied, it can be carried out, e.g., by means of a tightly fitting heating tool, which is either heated in advance or is provided with heating members and which is placed into the V-section groove 4 between the joint faces during the heating stage. After the joint faces have reached their melting temperature, the heating tool is removed and the mould tool 5 is applied.
However, a simpler procedure is to carry out the heating only after application of the mould tool 5. In this case the heating may take place either by means of a heated gaseous medium, which is injected into the hollow space between the mould tool 5 and the joint faces through the feed stub 6 or through a separate connection, or by means of radiation heat from a resistor wire in the mould tool.
The mould tool 5 has preferably a substantially U-shaped cross-section, and it is provided with a transverse articu¬ lated joint 8 for closing and opening of the mould tool 5. If the mould tool is supposed to be used for joining together of two tube ends, it has an annular shape and the feed stub 6 is fitted at the proximity of the trans¬ verse articulated joint 8.
An advantageous embodiment is obtained thereby that the mould tool is shaped as a flexible metal band, whose ends are provided with locking members for locking of the mould tool in the working position around the tubular plastic products to be joined together.
When the mould tool is intended for joining together of a split-open joint piece 2 between the protective and insulating layers 1 on two metal pipes 3 welded together in a pipeline for offshore, district-heating, or similar use, the mould tool 5 comprises two parallel portions 5a, which are supposed to enclose peripheral grooves 4 of their own, and one transverse portion 5b fitted between them for an axially directed groove 4. The connection stub 6 is appropriately fitted at the middle point of the transverse portion 5b.
In order that the mould tool should be suitable for joining together of joint pieces of different lengths, the trans- verse portion 5b is appropriately telescopic.
When a protective and insulating layer is applied onto a weld area between two metal pipes in a pipeline for off¬ shore or district-heating use, according to the present invention, it is also possible to omit the joint piece 2 completely and, in stead, to use a wider band-shaped mould tool 5 which covers the entire joint area. In order to reduce the quantity of molten plastic material that is to be injected in this connection, before applica- tion of the mould tool 5 it is possible to place a split- open tubular filler piece 2a in the space around the weld area, said filler piece having a thickness inferior to that of the protective and insulating layer 1 , which results in the circumstance that, in connection with the injection of the plastic mix, the filler piece 2a becomes completely baked-in in the wide joint 7 that is formed.

Claims

WHAT IS CLAIMED IS:
1. Method for joining together of tubular plastic products (1, 2) by fitting and fixing these in the desired position on the support of an inner tube (3) or a provisional support sleeve, by heating the joint faces of the plastic products (1, 2), which have been chamfered at least partly in advance, to the melting point of the plastic material, and by passing molten plastic material into the space (4) that is formed on the fitting together between the opposite joint faces, c h a r a c t e r i z e d in that the fixing of the tubular plastic products (1, 2) and the feed of the molten plastic material take place with the aid of a mould tool (5) which is applied onto the space (4) between the plastic products (1, 2) that are to be joined together, and the molten plastic material is passed rapidly under pressure into the hollow space between the mould tool (5) and the joint faces through at least one feed stub (6) provided in the mould tool, whereupon the plastic material is cooled and the mould tool (5) and an inner support bushing, if any, are removed.
2. Method as claimed in claim 1, c h a r a c t e r - i z e d in that the heating takes place by means of a heated gaseous medium which is injected into the hollow space between the mould tool (5) and the joint faces.
3. Method as claimed in claim 1, c h a r a c t e r - i z e d in that the heating takes place by means of a tightly fitting heating tool, which is placed into the groove (4) between the joint faces during the heating stage and which said heating tool must be removed before the mould tool (5) is applied.
4. Method as claimed in claim 1, c h a r a c t e r ¬ i z e d in that the heating takes place by means of radiation heat from a resistor wire in the mould tool (5).
5. Method as claimed in any of the claims 1 to 4, c h a r a c t e r i z e d in that the tubular plastic products (1, 2) consist of plastic tubes of, e.g., poly¬ olefin, which are joined together end to end, an inner collapsible support bushing being applied into the tube ends in the stage of fitting together.
6. Method as claimed in any of the claims 1 to 4, c h a r a c t e r i z e d in that a joint piece (2) that comprises a cylindrically split-open protective and insulating layer is applied around the joint area in a pipeline for offshore, district-heating or similar use, said pipeline being constructed of prefabricated metal pipes (3) of certain lengths provided with a protective and insulating layer (1), whereat the joint (7) at each joint piece (2) consists of two peripheral circular portions placed at each side of the joint piece (2) as well as of an axial portion along the splitting of same.
7. Method as claimed in any of the claims 1 to 4, c h a r a c t e r i z e d in that onto the weld joint between two metal pipes (3) provided with a protective and insulating layer (1), a tubular split-open filler piece (2a) of plastic is possibly applied, whose thickness is inferior to that of the protective and insulating layer (1), a wide band-shaped mould tool (5) with a feed stub (6) is applied onto the entire joint area, and plastic mix is injected into the space which is defined by the inner mantle of the mould tool (5), by the end faces of the protective and insulating layer (1), by the outer mantle of the metal pipe (3), and possibly by the mantle of the filler piece (2a) .
8. Device for joining together of tubular plastic product (1, 2) by passing molten plastic material into the space (4) between the tubular plastic products (1, 2) to be joined together, c h a r a c t e r i z e d in a mould tool (5) which can be applied onto the space (4) between the tubular plastic products (1, 2) to be joined together and which has an inner mould face of substantially concave- ly circular arcuate section, at least one centrally placed feed stub (6) for a supply pipe for molten plastic mate- rial, and one or several control openings at the point or points of the mould tool (5) that is/are placed most distant from the feed stub (6).
9. Device as claimed in claim 8, c h a r a c t e r - i z e d in that the mould tool (5) has a substantially
U-shaped section and a transverse articulated joint (8) for closing and opening the mould tool (5).
10. Device as claimed in claim 8, c h a r a c t e r - i z e d in that the mould tool (5) consists of a flexible metal band, whose ends are provided with locking members for locking the mould tool in the working position.
11. Device as claimed in claim 9 or 10, c h a r a c - t e r i z e d in that the mould tool (5) comprises two parallel portions (5a) for enclosing of peripheral seams and one transverse portion (5b) fitted between them for an axial seam, the feed stub (6) being fitted on said part.
12. Device as claimed in claim 11, c h a r a c t e r ¬ i z e d in that the transverse portion (5b) is telescopic.
13. Device as claimed in any of the claims 8 to 12, c h a r a c t e r i z e d in that the mould tool (5) is provided with a heating member, such as a resistor wire, for emission of radiation heat.
PCT/FI1989/000153 1988-08-23 1989-08-23 Method and device for joining together of tubular plastic products WO1990002038A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
FI883885A FI82635C (en) 1988-08-23 1988-08-23 Method and apparatus for joining tubular plastic products
DE68914996T DE68914996T3 (en) 1988-08-23 1989-08-23 METHOD AND DEVICE FOR CONNECTING TWO TUBULAR PLASTIC PRODUCTS.
AT8989909397T ATE104901T1 (en) 1988-08-23 1989-08-23 METHOD AND DEVICE FOR CONNECTING TWO TUBULAR PLASTIC PRODUCTS.
EP89909397A EP0431000B2 (en) 1988-08-23 1989-08-23 Method and device for joining together of tubular plastic products
CA000614466A CA1333653C (en) 1988-08-23 1989-09-29 Method and device for joining together of tubular plastic products
NO91910613A NO910613L (en) 1988-08-23 1991-02-15 PROCEDURE AND APPARATUS FOR COMPOSITION OF RUBERY PLASTIC PRODUCTS.

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI883885A FI82635C (en) 1988-08-23 1988-08-23 Method and apparatus for joining tubular plastic products
FI883885 1988-08-23
CA000614466A CA1333653C (en) 1988-08-23 1989-09-29 Method and device for joining together of tubular plastic products

Publications (1)

Publication Number Publication Date
WO1990002038A1 true WO1990002038A1 (en) 1990-03-08

Family

ID=25673145

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1989/000153 WO1990002038A1 (en) 1988-08-23 1989-08-23 Method and device for joining together of tubular plastic products

Country Status (9)

Country Link
US (1) US5238615A (en)
EP (1) EP0431000B2 (en)
JP (1) JP2710255B2 (en)
AT (1) ATE104901T1 (en)
CA (1) CA1333653C (en)
DE (1) DE68914996T3 (en)
FI (1) FI82635C (en)
NO (1) NO910613L (en)
WO (1) WO1990002038A1 (en)

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Also Published As

Publication number Publication date
US5238615A (en) 1993-08-24
FI82635C (en) 1991-04-10
EP0431000B1 (en) 1994-04-27
FI883885A (en) 1990-02-24
JPH04500179A (en) 1992-01-16
CA1333653C (en) 1994-12-27
DE68914996D1 (en) 1994-06-01
DE68914996T3 (en) 1999-07-29
NO910613D0 (en) 1991-02-15
ATE104901T1 (en) 1994-05-15
NO910613L (en) 1991-02-15
FI883885A0 (en) 1988-08-23
EP0431000B2 (en) 1998-12-30
JP2710255B2 (en) 1998-02-10
DE68914996T2 (en) 1994-12-22
FI82635B (en) 1990-12-31
EP0431000A1 (en) 1991-06-12

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