Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D23/00—Producing tubular articles
  • B29D23/001—Pipes; Pipe joints
  • B29D23/003—Pipe joints, e.g. straight joints
  • B29D23/005—Pipe joints, e.g. straight joints provided with electrical wiring
• • 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
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
  • B29C65/342—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint comprising at least a single wire, e.g. in the form of a winding
• • 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
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
  • B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
• • 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
  • B29C65/66—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
• • 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
  • B29C66/112—Single lapped joints
  • B29C66/1122—Single lap to lap joints, i.e. overlap 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
  • B29C66/71—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 composition of the plastics material of the parts to be joined
• • 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
  • F16L47/00—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics
  • F16L47/02—Welded joints; Adhesive joints
  • F16L47/03—Welded joints with an electrical resistance incorporated in the joint
• • 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
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
  • B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
  • B29C65/348—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic with a polymer coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene

Definitions

• This invention relates to polyethylene pipe with integrated elec ⁇ tric resistance thermowelding system. More particularly the invention relates to polyethylene socket-ended pipe, equipped with a cylindrical winding of metallic wire, firmly lodged within the socket, both ter ⁇ minals of which can be reached from the outside, so that two pipes can be permanently joined by thermowelding through insertion of unexpanded end into said socket and connection of wiring to electric power supply.
• thermowelding In case of polyethylene, being given its low melting point,as well as its features of fluidity and amalgability, junction by thermowelding is specially advantageous. Both edges to be joined are heated up to a tem ⁇ perature sufficient for causing some limited melting, then they are coupled, so that material, upon solidification, creates a continuity between the two pieces.
• Sleeve coupling systems with electrical resistance have been late ⁇ ly adopted, which doubtlessly offer a better guarantee for connection reliability and call for less assembly labor; they include a polyethylene sleeve whose inside diameter is about equal to the outside diameter of main pipe, which sleeve is fitted on the two pipe ends to be joined, and then thermowelding is performed through a wire coil covering its inside surface: when electric power is applied to said coil, heat produced by Joule effect causes the melting of the external surfaces of both the pipe ends as well as of the sleeve's internal surface. The two fused surfaces are mutually welded, thus forming one whole block.
• thermowelding junction system without using any additional element; this is made possible by associ ⁇ ation of the basic principle of bell joint with that of joint with sleeve and electric resistance.
• the invention therefore provides, at one end of each pipe bar, a bell type expanded portion, inside which a wire winding is lodged, whose terminals can be reached from outside, so that a simple and quick coupling by thermowelding can be performed through inserting the plain end of one pipe bar in the above-described expanded end of the next pipe bar.
• a polyethylene pipe with integrated electric resistance thermowelding system including a sub ⁇ stantially cylindrical expanded portion at one of its ends and a resistor formed by a wire coil, showing both terminal at the same end, the axial length of which does not exceed that of said expanded portion, and whose outside diameter practically coincides with the inside one of said ex ⁇ panded portion, and lodged inside same in such a way that both terminals can be reached from outside, the inside diameter of said resistor being equal, but for a small clearance, to pipe's outside diameter, so that the two ends of a pipe section be complementary.
• Pipe bar according to the invention can be connected one to an ⁇ other by inserting the unexpanded end of one into the complementary end of the other and by supplying electric power to the interposed resistor, in the amount required for heat-fusing the plastic material; it is clear that such a type of coupling is considerably more economic and easier to implement than the conventional ones.
• Pipe bars according to the invention can moreover be connected, by exploiting the proposed coupling system, to any fitting or piping com ⁇ ponent equipped with complementary ends.
• the terminal expanded portion can be manufactured separately and then fixedly connected to a plain pipe bar, but much more advantageously it can be formed by one socket integral with the pipe itself, obtained by working one of its ends.
• Axial length of the socket and of the resistor housed therein can vary according to pipe's NP, that is nominal pressure for which the pipe has been designed.
• the resistor is made up by one compact helical coil of wire covered by a thin poly ⁇ ethylene insulating layer; this makes the handling of resistor easier dur ⁇ ing the manufacture of the joint and, besides, while assembling the pipe the polyethylene covering melts thus adding continuity to the joint.
• Lugs can be joined to the resistance terminals at the edge of the socket, in order to ensure quick and steady connection to elec ⁇ tric power supply.
• Lugs are preferably housed In two hollows provided on the bell's Inside surface, adjacent to its edge. Alternatively a circular groove can be provided internally on the bell's edge, supplying the space required for lodging both lugs.
• Said lugs are oriented parallel to pipe axis, but it is also pos ⁇ sible to fasten them to the socket edge, so that orientation of their ends Is perpendicular to said axis.
• Another solution can be that of providing, instead of lugs, a couple of plugs passing through the thickness of bell wall and protruding outside, suitable for connection to female terminals.
• An alternative solution falling within the basic concept of this invention, provides for placing the electric winding outside the pipe's plain end, instead of inserting it within the socket end.
• a polyethylene pipe with integrated electric resistance thermowelding system including a substantially cylindrical expanded por ⁇ tion at one of its ends and a resistor formed by a wire coil, showing both terminals at the same end, the axial length of which does not ex ⁇ ceed that of said expanded portion, and whose inside diameter practically coincides with the outside one of said pipe, and being assembled around the plain end of the pipe, in such a way that said terminals be turned opposite the pipe edge, being the outside diameter of said resistor equal, but for a small clearance, to the inside diameter, of said expanded por ⁇ tion, so that the two ends of a pipe section be complementary.
• End 2 is a plain end of unworked pipe, while end 1 is provided with bell 3 and resistor 4, made up of a helical coil of wire.
• the re ⁇ sistor 4 looks like a compact block, since the wire is coated with a thin polyethylene layer making up its insulation, which makes it easier, as already said, the thermowelding of the two parts.
• Pipe shown is produced by a suitable bell-forming operation, which is performed directly after extrusion, through on-line process. Based on the times necessary for the bell-forming operation, which comprises an oven heating phase and an expanding phase, provision should be made for one or more parallel lines, connected to the extrusion one.
• the cylindrical resistor After expanding, the cylindrical resistor is inserted into the bell- shaped end, and then blocked in its housing by material's shrinkage, due to cooling. As a last phase, the pipe undergoes some quick cooling, for instance in a tank; said cooling blocks the socket in its shape, thus avoiding that it lose the shape obtained by the expansion, owing to poly ⁇ ethylene's strong thermic memory.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Branch Pipes, Bends, And The Like (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=11265712

Family Applications (1)

Country Status (11)

Families Citing this family (17)

Family Cites Families (3)

• 1986
  • 1986-07-22 IT IT8648290A patent/IT8648290A0/it unknown
• 1987
  • 1987-07-01 AU AU77016/87A patent/AU7701687A/en not_active Abandoned
  • 1987-07-01 JP JP62504055A patent/JPH01500452A/ja active Pending
  • 1987-07-01 EP EP87904404A patent/EP0283478A1/en not_active Withdrawn
  • 1987-07-01 WO PCT/IT1987/000067 patent/WO1988000668A1/en not_active Application Discontinuation
  • 1987-07-15 ZA ZA875163A patent/ZA875163B/xx unknown
  • 1987-07-17 YU YU01341/87A patent/YU134187A/xx unknown
  • 1987-07-18 CN CN198787104983A patent/CN87104983A/zh active Pending
  • 1987-07-21 GR GR871152A patent/GR871152B/el unknown
  • 1987-07-21 DD DD87305195A patent/DD263022A1/xx unknown
  • 1987-07-21 ES ES8702130A patent/ES2006523A6/es not_active Expired

Non-Patent Citations (1)

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