Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
  • G01K3/00—Thermometers giving results other than momentary value of temperature
• • 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
  • 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
  • B29C66/5229—Joining tubular articles involving the use of a socket
• • 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
  • 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
  • B29C66/73—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 intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/739—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 intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
  • B29C66/7392—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 intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
  • B29C66/73921—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 intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic characterised by the materials of both parts being thermoplastics
• • 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
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
  • B29C66/912—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux
  • B29C66/9121—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the temperature
  • B29C66/91211—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the temperature with special temperature measurement means or methods
  • B29C66/91218—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the temperature with special temperature measurement means or methods using colour change, e.g. using separate colour indicators
• • 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
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
  • B29C66/912—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux
  • B29C66/9121—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the temperature
  • B29C66/91221—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by measuring the temperature, the heat or the thermal flux by measuring the temperature 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
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/97—Checking completion of joining or correct joining by using indications on at least one of the joined parts
  • B29C66/976—Checking completion of joining or correct joining by using indications on at least one of the joined parts by the use of an indicator pin, e.g. being integral with one 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
• • 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
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/92—Measuring or controlling the joining process by measuring or controlling the pressure, the force, the mechanical power or the displacement of the joining tools
  • B29C66/929—Measuring or controlling the joining process by measuring or controlling the pressure, the force, the mechanical power or the displacement of the joining tools characterized by specific pressure, force, mechanical power or displacement values or ranges
• • 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
  • B29C66/90—Measuring or controlling the joining process
  • B29C66/97—Checking completion of joining or correct joining by using indications on at least one of the joined parts
  • B29C66/972—Checking completion of joining or correct joining by using indications on at least one of the joined parts by extrusion of molten material

Definitions

• the invention relates to a sleeve-shaped weld connecting piece of thermoplastic material for connecting thermoplastic pipes comprising a heating element embedded near the inside wall, and also a pin- shaped weld indicator element which is disposed in a bore in the wall and retained therein.
• the weld indicator element comprises a pin which is retained in a bore and has a flange-shaped element at its bottom side.
• This known sleeve-shaped weld connecting piece has the disadvantage that only an extremely small difference in size between the internal dimensions of the weld connecting piece and the external dimensions of the pipe is permitted, since with greater play between weld connecting piece and pipe the gap between the two parts is not always closed by shrinkage of the weld connecting piece, and one cannot therefore be sure of the required pressure build-up for moving the pin, while welding still takes place.
• this known weld indicator element therefore often does not meet the requirements set.
• this known colour changeable indicator element presents the disadvantage that due to the rather great wall thickness of the connecting piece a long time is required before the small temperature increase generated during welding reaches the colour changeable indicator element.
• the object of the invention is now to provide a weld connecting piece of the type mentioned at the beginning with which, even where there is greater play between weld connecting piece and pipe to be connected thereto, or where there is a great wall thickness between the actual welding site and the outer side of the connecting piece a faultless indication is given by the weld indicator element when the weld is produced.
• the weld indicator element is provided with additional means enhancing the visibility of the welding action at the outer side of the connecting piece and said additional means being activatable by heat generated during welding.
• the weld indicator element is provided with additional means in the form of pressure means which subject the weld indicator element to an outward-directed pressure at least during welding together of the weld connecting piece and the pipe part, so that the weld indicator element is thereby pressed out.
• the pressure means particularly advantageously subject the weld indicator element constantly to an outward-directed pressure force. With the presence of such pressure means the weld indicator element is subjected constantly to an outward-directed pressure force, so that immediately after softening of the bottom part of the bore the weld indicator element is no longer retained and is pressed out by the pressure means.
• the pressure means prefferably contains a spring means placed in a bore part, said spring means interacting with a projecting part of the weld indicator element, in particular a flange provided on the top side of the weld indicator element.
• the weld connecting piece is constantly subjected to an outward-directed pressure force, but through the retention of the weld indicator element in the bore, it cannot move outwards.
• the weld indicator element is no longer retained, due to the softening of the plastic mass, the element will be pressed out immediately in order to indicate that a welding operation has taken place.
• the pressure means expediently comprise a coil spring which is integral with the weld indicator element and is connected to the top side of the weld indicator element.
• the coil spring can be made of the same material as the weld indicator element, for example plastic, since the coil spring lies a great distance away from the heated part of the weld connecting piece.
• the pressure means can expediently comprise a leaf spring, in which case one can use a pin carrying at its top side a curved plate which is pressed flat when the pin is placed in the bore and is held like this by the pin until during welding the retaining means for the pin can no longer make up for the tension in the deformed plate.
• This design has the advantage that the weld indicator element can be formed in one operation.
• the weld indicator element expediently has a container which is open at the top side and contains an expandable solid medium.
• the expandable medium is a foa able medium, more particularly a foamable plastic compound.
• the container for the expandable medium is expediently a metal container.
• the pin-shaped weld indicator element is advantageously made of a plastic, more particularly of polyoxymethylene.
• weld indicator element With the use of such a material for the weld indicator element, it can immediately be made integral with a leaf spring or with a coil spring.
• the weld indicator element is a well heat conducting element extending to the vicinity of the heating element and engages a colour changeable element changing its colour at elevated temperature.
• this temperature in the welding zone is substantially higher than the temperature as reached during storage and/or transport, it is possible to use a colour which will not change at temperatures occurring during transport and/or storage.
• the well heat conducting metal element is broadened at its upper and/or lower side so that the colour changeable element is subjected to the temperature in the welding zone as strong as possible.
• the weld indicator element comprises a metal pin engaging a colour changeable element at its upper side. In this manner an optimal quantity of heat is supplied to the colour changeable element.
• the sleeve-shaped weld connecting piece of thermoplastic material is advantageously a polyolefin, for example polyethylene or polypropylene, while the thermoplastic pipes to be welded thereto are also made of a polyolefin.
• the sleeve-shaped weld connecting piece is in particular suitable for the production of pipelines for carrying gas, but the invention is not limited to this.
• the invention also relates to a welded joint of a sleeve-shaped weld connecting piece with at least one pipe accommodated therein and connected thereto by welding, which is characterized in that a sleeve- shaped weld connecting piece according to the invention is used.
• Fig. 1 shows a longitudinal section of a first embodiment of a sleeve-shaped weld connecting piece according to the invention
• Fig. la shows a cross-section of a variant of a weld connecting piece according to Fig. 1;
• Fig. lb shows the same cross-section as that in Fig. la, but after the welded joint has been produced;
• Fig. 2 shows a view of a variant of a sleeve-shaped weld connecting piece according to the invention
• Fig. 2a shows the same view as that of Fig. 2 after the welded joint has been produced
• Fig. 3 shows a longitudinal section of yet another embodiment of a sleeve-shaped weld connecting piece according to the invention
• Fig. 3a shows the same cross-section as that in Fig. 3, but after the welded joint has been provided;
• Fig. 4 shows a part of another sleeve-shaped weld connecting piece according to the invention with a foamable medium in a container;
• Fig. 4a shows the same longitudinal section as that in Fig. 4 after a welded joint has been formed.
• Fig. 5 shows a longitudinal section of still another weld connecting piece of the invention with a colour change element and Fig. 6 a detail of a variant of a weld connecting piece according to Fig. 5.
• Fig. 1 shows a longitudinal section of a polypropylene welding sleeve 1 for connecting polypropylene pipes 2 by means of a welded joint. Embedded near the inside wall 3 of the welding sleeve
• a metal heating element 4 which at its ends bears connecting parts 9, 9a accommodated in connecting chambers 10 and 10a.
• the welding sleeve 1 also has two bores 5 in the wall 6 which extend with their bottom 8 to near the heating element 4.
• the bottom 8 contains a recess 11 in which is clamped a narrowed part 22 of a weld indicator element in the form of a polyoxymethylene pin 7 which at its top side bears a flange 13 formed of polyoxymethylene material.
• the flange 13 is accommodated in a circular bore part 5' in the outside wall of the welding sleeve.
• the bore 5 has near its top side a circular boundary edge 17, while the pin can bear near its bottom side a circular collar 18' which has greater dimensions than the edge 17.
• the opening formed by the circular edge 17 is greater than the dimension of the pin 7, so that the latter can pass the edge 17 during the outward movement.
• the latter in order to ensure a particularly good fixing of the pin 7 in the bore 5, can also bear near its bottom 8 a circular recess 12 into which a projecting rib 16 of the pin 7 snaps.
• the plastic begins to melt in the region of the circular recess 11, with the result that the pin 7 is no longer retained in the circular recess 12, and therefore through the compression being removed the spring 15 presses the pin 7 upwards.
• Such a design has the great advantage that the weld indicator element is easy to manufacture, very reliable, and creep-resistant, while damage does not affect the reliability, and the weld indicator element does not depend on the welding pressure.
• Fig. 2 shows another embodiment in which the weld indicator element again comprises a pin 7 of polyoxymethylene material retained in a bore 5.
• This pin 7 is integral with a coiled strip 23, also made of polyoxymethylene material.
• This coiled strip which is connected at a point 24a to an outer closed circular strip 24, forms a coil spring 18 which is retained in a bore 5.
• the circle is fixed by a circular collar 26 in a widened part 25 of bore part 5'.
• Fig. 2a it can be seen how the coil spring 18 has developed after the welded joint has been produced and the pin 7 is therefore pressed out.
• the helical, line decreases upwards, so that the strip 23 can be deformed to the flat coil shown in Fig. 2.
• the strip 23 is connected at 26 to the polyoxymethylene pin 7.
• This weld indicator element is also simple to manufacture and easy to install, and damage does not have any influence on the reliability of the element.
• Fixing coil spring 18 in bore part 5' in the outside wall of the welding sleeve means that the indicator can be prevented from being pressed fully out of the recess or bore 5.
• Fig. 3 shows another embodiment, comprising a pin 7 having a leaf spring 19 integral therewith.
• the leaf spring 19 in its original state has a curved shape. After positioning the pin 7 in the bore 5, the leaf spring 19 is, however, pressed flat, so that it adapts to the shape of the outside wall of the welding sleeve and is accommodated in bore part 5'.
• Fig. 4 shows another embodiment, in which the weld indicator element comprises a metal box 21 filled with non-expanded polystyrene foam 20.
• the temperature increases, causing heat to spread through the metal box 21 over the non-expanded polystyrene foam compound.
• the polystyrene then expands, so that the material will move out of the box and forms indicator element 7'.
• the container or the metal box 21 is anchored in the wall of the weld connecting piece in order to prevent plastic flowing through this bore 5 during welding from running out.
• Such a weld indicator element has the great advantage of small dimensions.
• weld indicator element made from two boxes which are bonded together, for example by polyethylene, and which contain a compression spring. Through the heat of a weld, the adhesive join is then broken, and one of the boxes is pressed out.
• FIG. 5 shows another embodiment of the invention.
• the bores 5 contain a metal pin 7 supporting at its upper side a sticker 27 of colour changeable material, which changes its colour at elevated temperatures, such as temperatures near the welding temperature generated by heating element 4.
• the pin 7 may be provided with a broadened foot 9a.
• the bore 8 is provided with an enlarged chamber 11 near the welding sleeve outer wall. The chamber 11 accommodates a head 12 of pin 9 bearing an enlarged sticker 10' of colour changeable material (vide fig. 6) .

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26646518

Family Applications (1)

Country Status (3)

Cited By (6)

Citations (13)

• 1990
  • 1990-04-27 EP EP90907516A patent/EP0470170A1/de not_active Withdrawn
  • 1990-04-27 WO PCT/NL1990/000059 patent/WO1990013411A1/en not_active Application Discontinuation
  • 1990-04-27 AU AU55698/90A patent/AU5569890A/en not_active Abandoned

Patent Citations (13)

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