GB2299291A - Manufacturing plastics pipe with a socket by injection moulding - Google Patents

Manufacturing plastics pipe with a socket by injection moulding Download PDF

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Publication number
GB2299291A
GB2299291A GB9613116A GB9613116A GB2299291A GB 2299291 A GB2299291 A GB 2299291A GB 9613116 A GB9613116 A GB 9613116A GB 9613116 A GB9613116 A GB 9613116A GB 2299291 A GB2299291 A GB 2299291A
Authority
GB
United Kingdom
Prior art keywords
socket
pipe
heat generating
plastic pipe
mold
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
GB9613116A
Other versions
GB9613116D0 (en
GB2299291B (en
Inventor
Yuichiro Goto
Takatomo Harada
Hideki Kasa
Takashi Tago
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kubota Corp
Original Assignee
Kubota Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kubota Corp filed Critical Kubota Corp
Priority claimed from GB9318465A external-priority patent/GB2272663B/en
Publication of GB9613116D0 publication Critical patent/GB9613116D0/en
Publication of GB2299291A publication Critical patent/GB2299291A/en
Application granted granted Critical
Publication of GB2299291B publication Critical patent/GB2299291B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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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
    • 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
    • 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"
    • B29C65/3404—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
    • B29C65/3444—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 being a ribbon, band or strip
    • 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
    • B29C65/3444—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 being a ribbon, band or strip
    • B29C65/3448—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 being a ribbon, band or strip said ribbon, band or strip being perforated
    • 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
    • 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
    • B29C66/01—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
    • B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
    • B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
    • B29C66/1222—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least a lapped joint-segment
    • 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
    • B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
    • B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
    • B29C66/1224—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least a butt joint-segment
    • 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
    • B29C66/50—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
    • B29C66/5223—Joining tubular articles for forming corner connections or elbows, e.g. for making V-shaped pieces
    • B29C66/52231—Joining tubular articles for forming corner connections or elbows, e.g. for making V-shaped pieces with a right angle, e.g. for making L-shaped pieces
    • 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
    • B29C66/5224—Joining tubular articles for forming fork-shaped connections, e.g. for making Y-shaped pieces
    • B29C66/52241—Joining tubular articles for forming fork-shaped connections, e.g. for making Y-shaped pieces with two right angles, e.g. for making T-shaped pieces
    • 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
    • B29C66/5229—Joining tubular articles involving the use of a socket
    • B29C66/52291—Joining tubular articles involving the use of a socket said socket comprising a stop
    • B29C66/52292—Joining tubular articles involving the use of a socket said socket comprising a stop said stop being internal
    • 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"
    • B29C65/3468—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 means for supplying heat to said heated elements which remain in the join, e.g. special electrical connectors of windings
    • 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
    • B29C65/3484—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 non-metallic
    • B29C65/3488—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 non-metallic being an electrically conductive polymer
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Branch Pipes, Bends, And The Like (AREA)

Abstract

A method of manufacturing a plastic pipe is disclosed in which a socket is formed on at least one end of a plastic pipe (12') and a heating unit (86) is disposed in the socket. An injection mold (68) is utilized in which the heating unit (86) is mounted on a core mold (80) defining the inner surface of the socket and the mold (68) is closed by means of outer moulds 70, 72 so that a cavity defining the socket is formed at the end of the pipe (12') received on another core mould 96. Synthetic resin material is injected into the cavity. After curing, the pipe (12') with the socket formed thereon is released from the mold (68).

Description

A METHOD OF MANIJFACTURINO A PLASTIC PIPE The present invention relates to a method of manufacturing a plastic pipe. More specifically, the present invention relates to a method of a manufacturing plastic pipe used for electro-fusion coupling having a socket on at least one end.
In the past, in order to couple two plastic pipes to each other by electro-fusion coupling, an electro-fusion fitting formed by injection moulding was utilized (see Figure 11). The electro-fusion fitting 1 includes an approximately hollow cylinder-like body 2 made of synthetic resin, and an electric heating wire 3 which is wound in a form of a coil is embedded in the vicinity of an inner surface of the body 2, and both ends of the electric heating wire 3 are connected to terminals 4 formed so as to project from the body 2. Then an outer periphery of each end of pipes 5 and 6 to be coupled to each other is scraped by a scraper or the like and the ends are inserted into the body 2, and a heating electric power source (not shown) is connected to the terminals 4 to supply an electric power source to the electric heating wire 3.
In this prior art, since the electro-fusion fitting 1 is formed by injection moulding, it was necessary to prepare a dedicated mould for each kind of elbows, tees, and etc.
resulting in high overall cost.
Furthermore, since the outer peripheries of the ends of the pipes 5 and 6 are scraped by the scraper or the like, there was a problem that a workability is poor.
In addition, since the pipes 5 and 6 are respectively inserted into both sockets of the body 2 such that the body 2 and the pipe 5, and the body 2 and the pipe 6 are fused and adhered to each other, respectively, the amount of heat necessary for such fusion coupling is large. A further problem is that it is necessary to use a heating electric power source having a larger capacity or to prolong a power supply time.
It is an object of the present invention to overcome or substantially alleviate the aforementioned problems by providing a method in which a plastic pipe with a socket on one end is manufactured.
According to the present invention, there is provided a method of manufacturing a plastic pipe with a socket on at least one end thereof including a heat generating unit in the socket comprising the steps-of: a) taking a length of plastic pipe; b) mounting the heat generating unit on a first core mold defining the inner surface of the socket; c) assembling the first core mold and heat generating unit with a second core mold defining an inner surface of the pipe and inserting the second core mold into the pipe; d) forming a cavity around the end of the plastic pipe and heat generating unit by closing an outer mold; e) forming the socket integrally with the plastic pipe and the heat generating unit by injecting synthetic resin into the cavity; and f) releasing the plastic pipe with the socket formed thereon from the first and second core molds by opening the outer mold.
Therefore, it is possible to simply manufacture a plastic pipe having a socket which is provided with the heat generating unit on an inner surface or in the vicinity of the inner surface of the socket.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention given by way of example only, when taken in conjunction with the accompanying drawings.
Figure 1 is a cross-sectional illustrative view showing a plastic pipe made in accordance with the method of the present invention; Figure 2 is a perspective view showing a heat generating unit utilized in the plastic pipe shown in Figure 1; Figures 3 to 5 are cross-sectional illustrative views respectively showing modified examples of the heat generating unit shown in Figure 2; Figure 6 is an illustrative view showing a mold utilized in the manufacturing method of the plastic pipe shown in Figure 1 according to the present invention; Figure 7 is a cross-sectional view at a line XII-XII in Figure 6; Figure 8 is a cross-sectional view at a line XIII-XIII in Figure 6; Figure 9 is a cross-sectional illustrative view showing a modified plastic pipe made in accordance with the method of the present invention;; Figure 10 is a cross-sectional view showing a modified plastic pipe made in accordance with the method of the present invention; and Figure 11 is an illustrative view showing a prior art electro-fusion coupling.
Referring to Figure 1, a plastic pipe 10 which can be manufactured according to the invention is shown and includes a pipe body 12 made of a synthetic resin such as polyethylene, polybutene, and etc. At one end or both ends of the pipe body 12, a portion where a diameter is increased, that is, a socket 16 is formed via an inclined or tapered portion, and an inside of the socket 16, a heat generating unit 18 as shown in Figure 2 is mounted.
The heat generating unit 18 includes an approximately cylinder-like body 20 having an outer periphery capable of being closely fitted to an inner surface of the socket 16 and made of synthetic resin such as polyethylene, polybutene, and etc., and a flange 22 having a side surface capable of being brought into contact with an end surface of the socket 16 is formed on the outer periphery of an end of the body 20. Furthermore, a coated electric heating wire 24 is embedded inside the body 20 with a double-folded state, and terminals 26 provided on the flange 22 are connected to both ends of the coated electric heating wire 24.In addition, such heat generating unit 18 is formed in a manner that the coated electric heating wire 24 is wound on an outer periphery of a core mold (not shown) and then synthetic resin such as polyethylene, polybutene, and etc. is injected so as to cover the coated electric heating wire 24.
In order to prevent a step from being formed on an inner surface of a pipeline, a spacer 30 having an approximately triangular configuration in cross-section and capable of being brought into contact with an end surface of a pipe 28 to be coupled to the plastic pipe 10 is attached on an inner surface of the tapered portion 14 in a back of the heat generating unit 18.
In coupling, an outer periphery of the end of the pipe 28 to be coupled is scraped by a scraper or the like, and the end is inserted into the heat generating unit 18, that is, a socket 16 having a larger diameter of the pipe. Then, the socket 16 and the pipe 28 are sandwiched by a cramping tool 32 to be fixed to each other, and a heating electric power source (not shown) is connected to the terminals 26 to supply an electric power to the coated electric heating wire 24. Then, the coated electric heating wire 24 generates a heat due to an ohmic resistance component thereof, and the heat generating unit 18 and the socket 16, and the pipe 28 are fused and adhered to each other, whereby the pipe 10 and the pipe 18 are coupled to each other.
Since an electro-fusion fitting as such the prior art is not required, it is possible to perform electro-fusion coupling with a low cost. Furthermore, since a coupling portion can be made small, it becomes possible to preform the coupling within a small space.
Furthermore, in coupling, only the outer periphery of the end of the pipe 28 may be scraped by the scraper or the like, and therefore, a time and labour for the scraping becomes to be halved in comparison with the prior art, and therefore, it is possible to -greatly increase the workability.
Furthermore, it is possible to make an area of the electro-fusion coupling approximately half of that of the prior art, and therefore, the reduction of the capacity of the electric power source as well as the shortening of the power supply time to the coated electric heating wire 24 can be expected.
Furthermore, since the socket 16 can be sandwiched by the clamping tool 32, it is possible to closely fit the pipe 28 to the heat generating unit 18 and the socket 16, and therefore, it is possible to prevent poor electro-fusion coupling from occurring.
According to the preferred embodiment of the invention, a manufacturing method of a plastic pipe is shown in Figures 6 to 8 in which an injection mold 68 is utilized.
The mold 68 includes an upper mold 70 and a lower mold 72 which are opened or closed in an up-down direction, and an oil hydraulic cylinder 74 is attached on a front surface of the lower mold 72 by a bolt 76. Within a space defined by the upper mold 70 and the lower mold 72, a first core mold 80 capable of being slidably moved by a piston 78 which is extended from the oil hydraulic cylinder 74 is arranged. Furthermore, a gate 84 for injecting synthetic resin into a cavity 82 is formed on an upper surface of the upper mold 70.
In manufacturing the plastic pipe 10, at first, a heat generating unit 86 is mounted on the first core mold 80.
The heat generating unit 86 includes an approximately hollow cylinder-like mat 88 composed of the same resin material as that of the pipe 12', for example, and on an outer periphery of the mat 88, a coated electric heating wire 92 which is provided with terminals 90a and 90b at both ends thereof are wound. After such the heat generating unit 86 is mounted on the first mold 80, terminal fixing members 94a and 94b are attached to the terminals 90a and 90b, respectively, and the terminal fixing members 94a and 94b are fixed at predetermined positions corresponding to positions at which the terminals 90a and 90b are to be formed. Then, a pipe 12' having an end to which a second core mold 96 is inserted is arranged at a predetermined portion within the mold 68, and then, the upper mold 70 and the lower mold 72 are closed.Thereafter, a nozzle 98 (Figure 8) of an injection molding machine (not shown) is connected to the gate 84, a synthetic resin material is injected from the nozzle 98 into the cavity 82. After the synthetic resin material is cured, the upper mold 70 and the lower mold 72 are opened, the plastic pipe 10 thus molded is released from the mold 68. In addition, in this manufacturing method, an arbitrary one of the above described heat generating units 18,48,52,56 and etc. can be used, and in a case where the heat generating unit 48,52 or 56 to which a current is applied through the electromagnetic induction is utilized, it is not necessary to provide the terminal fixing members 94a and 94b.
In addition, the plastic pipe made by the method of the invention are straight pipes, however, the described methods may also be used to manufacture plastic pipes 10 shaped as a tee 104 shown in Figure 7 or an elbow 106 shown in Figure 8. The tee 104 shown in Figure 7 includes sockets 16 at respective ends of an ordinary tee, and heat generating units 18 are mounted in the sockets 16 at respective ends of an ordinary elbow, and heat generating units 18 are mounted in the sockets 16.
In such cases, of course, it is possible to apply an arbitrary one of the above described heat generating units 48, 52, 56, 86 and etc.
This application is divided out of UK patent application No.9318465.3 (GB 2272663).

Claims (2)

1. A method of manufacturing a plastic pipe with a socket on at least one end thereof including a heat generating unit in the socket comprising the steps of: a) taking a length of plastic pipe; b) mounting the heat generating unit a first core mold defining the inner surface of the socket; c) assembling the first core mold and heat generating unit with a second core mold defining an inner surface of the pipe and inserting the second core mold into the pipe; d) forming a cavity around the end of the plastic pipe and heat generating unit by closing an outer mold; e) forming the socket integrally with the plastic pipe and the heat generating unit by injecting synthetic resin into the cavity; and f) releasing the plastic pipe with the socket formed thereon from the first and second core molds by opening the outer mold.
2. A method of manufacturing a plastic pipe substantially as hereinbefore described.
GB9613116A 1992-01-06 1992-12-28 A method of manufacturing a plastic pipe Expired - Fee Related GB2299291B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP8692 1992-01-06
GB9318465A GB2272663B (en) 1992-01-06 1992-12-28 A method of manufacturing a plastic pipe

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GB9613116D0 GB9613116D0 (en) 1996-08-28
GB2299291A true GB2299291A (en) 1996-10-02
GB2299291B GB2299291B (en) 1996-12-11

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29707540U1 (en) * 1997-04-25 1997-07-31 Schieffer GmbH & Co. KG, 59557 Lippstadt Hose, preferably high pressure hose, with connector
GB2325636A (en) * 1997-05-31 1998-12-02 Dalatek Ltd Improvements in or relating to pipes
CN107297857A (en) * 2017-08-11 2017-10-27 西安奥若特材料技术有限公司 A kind of thermoplastic material pipe connection method

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1133904A (en) * 1966-04-20 1968-11-20 Ispra Spa Machine for moulding coupling ends onto pipes
EP0457342A2 (en) * 1990-05-17 1991-11-21 Nippon Zeon Co., Ltd. Pipe with integrally moulded coupler and method therefor
EP0535247A1 (en) * 1991-04-19 1993-04-07 Sekisui Kagaku Kogyo Kabushiki Kaisha Pipe joint member

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1133904A (en) * 1966-04-20 1968-11-20 Ispra Spa Machine for moulding coupling ends onto pipes
EP0457342A2 (en) * 1990-05-17 1991-11-21 Nippon Zeon Co., Ltd. Pipe with integrally moulded coupler and method therefor
EP0535247A1 (en) * 1991-04-19 1993-04-07 Sekisui Kagaku Kogyo Kabushiki Kaisha Pipe joint member

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29707540U1 (en) * 1997-04-25 1997-07-31 Schieffer GmbH & Co. KG, 59557 Lippstadt Hose, preferably high pressure hose, with connector
GB2325636A (en) * 1997-05-31 1998-12-02 Dalatek Ltd Improvements in or relating to pipes
GB2325636B (en) * 1997-05-31 2002-04-17 Dalatek Ltd Improvements in or relating to pipes
CN107297857A (en) * 2017-08-11 2017-10-27 西安奥若特材料技术有限公司 A kind of thermoplastic material pipe connection method

Also Published As

Publication number Publication date
GB9613116D0 (en) 1996-08-28
GB2299291B (en) 1996-12-11

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