DE4343449C2 - Process for electric welding - Google Patents

Process for electric welding

Info

Publication number
DE4343449C2
DE4343449C2 DE4343449A DE4343449A DE4343449C2 DE 4343449 C2 DE4343449 C2 DE 4343449C2 DE 4343449 A DE4343449 A DE 4343449A DE 4343449 A DE4343449 A DE 4343449A DE 4343449 C2 DE4343449 C2 DE 4343449C2
Authority
DE
Germany
Prior art keywords
welding
heating
plastic
pipe
fitting
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.)
Expired - Lifetime
Application number
DE4343449A
Other languages
German (de)
Other versions
DE4343449A1 (en
Inventor
Rainer Mueller
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.)
Friatec AG
Original Assignee
Friatec AG
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 Friatec AG filed Critical Friatec AG
Priority to DE4343449A priority Critical patent/DE4343449C2/en
Priority to CN94119350A priority patent/CN1052441C/en
Publication of DE4343449A1 publication Critical patent/DE4343449A1/en
Application granted granted Critical
Publication of DE4343449C2 publication Critical patent/DE4343449C2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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
    • 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
    • B29C65/02—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
    • B29C66/02—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
    • B29C66/50—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
    • B29C66/53—Joining single elements to tubular articles, hollow articles or bars
    • B29C66/534—Joining single elements to open ends of tubular or hollow articles or to the ends of bars
    • B29C66/5344—Joining single elements to open ends of tubular or hollow articles or to the ends of bars said single elements being substantially annular, i.e. of finite length, e.g. joining flanges to tube ends
    • 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
    • B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9141—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature
    • B29C66/91411—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
    • 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
    • B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
    • B29C66/91641—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time
    • B29C66/91643—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time following a heat-time profile
    • B29C66/91645—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time following a heat-time profile by steps
    • 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
    • B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
    • B29C66/91651—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating
    • B29C66/91653—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating by controlling or regulating the voltage, i.e. the electric potential difference or electric tension
    • 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
    • B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
    • B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
    • B29C66/91651—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating
    • B29C66/91655—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating by controlling or regulating the current intensity
    • 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
    • B29C66/919—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux 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
    • B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
    • B29C66/919—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges
    • B29C66/9192—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams
    • B29C66/91921—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature
    • B29C66/91931—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature in explicit relation to the fusion temperature or melting point of the material of one of the parts to be joined
    • B29C66/91935—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams in explicit relation to another temperature, e.g. to the softening temperature or softening point, to the thermal degradation temperature or to the ambient temperature in explicit relation to the fusion temperature or melting point of the material of one of the parts to be joined lower than said fusion 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
    • 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
    • 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
    • B29C66/94—Measuring or controlling the joining process by measuring or controlling the time

Description

Die Erfindung bezieht sich auf ein Verfahren zum Elektroschweißen gemäß den im Oberbegriff des Patentanspruchs 1 angegebenen Merkmalen.The invention relates to a method for electric welding according to the The preamble of claim 1 features specified.

Aus der DE 29 47 166 C1 ist ein derartiges Verfahren bekannt, bei welchem Schweiß muffen mit Schrumpfreserve zum Einsatz gelangen. Die Rückbildung der Schrumpfreserve kann bei derartigen Schweißmuffen bereits im kalten Zustand während der Lagerung auftreten. Beim Schweißen und Erwärmen des thermoplastischen Materials der Schweißmuffe wird die Schrumpfreserve gelöst, um ein Aufschrumpfen in radialer Richtung auf das Rohr zu erhalten. Hierbei kann das Problem auftreten, daß die Windun­ gen des Heizdrahtes gegeneinander verrutschen und Kurzschlüsse auftreten, zumal beim Schweißen und Erwärmen der Heizdraht eine Ausdehnung erfährt. Um dies zu verhindern, wird die Schweißmuffe zunächst vorerwärmt, so daß eine langsame Schrumpfung erfolgt, wobei sich die Windungen des Heizdrahtes im Muffenmaterial nur radial und nicht gegeneinander verlagern.Such a method is known from DE 29 47 166 C1, in which sweat must be used with a shrink reserve. The regression of the With such welding sleeves, the shrink reserve can already be in the cold state during of storage occur. When welding and heating the thermoplastic material the welding sleeve loosens the shrink reserve to shrink in radial To get direction on the pipe. The problem may arise here that the wind shift against each other and short circuits occur, especially since expands when welding and heating the heating wire. To do this prevent, the welding sleeve is first preheated, so that a slow Shrinkage occurs, with the turns of the heating wire only in the sleeve material move radially and not against each other.

Aus der DE 35 40 193 C1 ist ein Elektroschweißfitting oder Schweißmuffe bekannt, welche in der Außenfläche eine spiralförmige Nut mit einer als Armierung ausgebildeten Wicklung versehen ist. Hierdurch wird eine Reduzierung der Wandstärke des Fittings oder der Muffe und ein reduzierter Materialeinsatz ermöglicht, und gleichwohl wird beim Schweißen eine unerwünscht starke Aufweitung des Schweißfittings oder der Schweiß muffe verhindert und der zum Schweißen erforderliche Anpressdruck bezüglich des Rohres aufrechterhalten.From DE 35 40 193 C1 an electric welding fitting or welding sleeve is known, which has a spiral groove in the outer surface with a reinforcement Winding is provided. This will reduce the wall thickness of the fitting or the sleeve and a reduced use of materials enables, and nevertheless at Welding an undesirably large expansion of the weld fitting or sweat prevents sleeve and the contact pressure required for welding with respect to the Tube maintained.

Ferner ist aus der DE 36 00 156 A1 ein Verfahren zur Herstellung einer Schweißverbin­ dung zwischen Kunststoffrohren bekannt, demgemäß der Heizdraht in der Innenfläche der Muffe angeordnet ist. Infolge von Fertigungstoleranzen oder Verformungen der Muffen oder Rohrenden bei der Lagerung und beim Transport können Spalte zwischen der Muffeninnenfläche und dem eingeschobenen Rohrende auftreten, wodurch die Güte der Verschweißung und die Dichtigkeit der Schweißverbindung in Frage gestellt werden können. Furthermore, DE 36 00 156 A1 describes a method for producing a welded joint tion between plastic pipes known, accordingly the heating wire in the inner surface the sleeve is arranged. As a result of manufacturing tolerances or deformations of the Sleeves or pipe ends during storage and transport can cause gaps between the inside surface of the sleeve and the inserted pipe end occur, which reduces the quality the welding and the tightness of the welded connection are questioned can.  

Des weiteren ist aus der DE 38 10 795 A1 ein Elektro-Schweißgerät zum selbsttätigen Schweißen von Heizwendel-Fittings oder Elektroschweißfittings bekannt. Die insbesonde­ re von der Höhe und Dauer des Schweißstromes und der anliegenden Spannung abhängige Schweißenergie wird bei diesem Schweißgerät über eine Kennkarte gesteu­ ert, welche mit dem Fitting verbunden ist und von welcher mittels eines Abtasters die maßgeblichen Daten für das Elektro-Schweißgerät erfaßt und zur Regelung des Schweißvorganges genutzt werden. Zusätzlich kann mittels eines Temperaturfühlers die Umgebungstemperatur zur Korrektur der Soll-Schweißarbeit erfaßt werden. In der Praxis ergeben sich Probleme durch einen zu großen und/oder unregelmäßigen Spalt zwi­ schen den zu verschweißenden Flächen, wobei Fertigungstoleranzen ebenso wie Verformungen und Unrundheiten der Rohre infolge deren Lagerung sich ergeben können Die genannten Schwierigkeiten treten vor allem bei Rohren mit größeren Durchmessern auf, und zwar ab 280 mm und darüber. So wurden bei Rohren mit Durchmessern 450 mm, wobei für solche Rohre regelmäßig Fittings mit Armierungen zum Einsatz gelangen, Toleranzen bzw. Spaltbreiten von ca. 5-6 mm festgestellt. Es bedarf keiner besonderen Hervorhebung, daß derartige Spalte über den Umfang keine konstante Breite aufweisen, sondern zwischen Null und maximalem Abstand variieren. An den Stellen mit geringster Spaltbreite oder Berührung zwischen Fittingfläche und Rohrfläche erfolgt eine stärkere Erwärmung als in den Bereichen mit großen Spaltbreiten, wobei Unregelmäßigkeiten der Schweißgüte, Lufteinschlüsse oder Lunker in der Praxis nicht mit der erforderlichen Sicherheit vermieden werden können.Furthermore, DE 38 10 795 A1 describes an electric welding machine for automatic operation Welding heating coil fittings or electrowelding fittings is known. The in particular right of the level and duration of the welding current and the applied voltage dependent welding energy is controlled in this welding machine via an identification card ert, which is connected to the fitting and of which by means of a scanner relevant data for the electric welding machine and to regulate the Welding process can be used. In addition, the Ambient temperature to correct the target welding work can be detected. In practice problems arise due to a too large and / or irregular gap between the surfaces to be welded, whereby manufacturing tolerances as well Deformations and out-of-roundness of the pipes as a result of their storage can result The difficulties mentioned occur above all in pipes with larger diameters on, from 280 mm and above. For example, 450 mm, whereby fittings with reinforcements are regularly used for such pipes, Tolerances or gap widths of approx. 5-6 mm determined. No special one is required Emphasizing that such gaps do not have a constant width over the circumference, but vary between zero and maximum distance. At the points with the least The gap width or contact between the fitting surface and the pipe surface is greater Warming than in the areas with large gap widths, with irregularities of the Welding quality, air pockets or cavities in practice not with the required Security can be avoided.

Hiervon ausgehend liegt der Erfindung die Aufgabe zugrunde, ein Verfahren vor­ zuschlagen, durch welches die oben aufgezeigten Nachteile vermieden werden und welches bei einfacher Durchführbarkeit eine optimierte Verschweißung ermöglicht. Das Verfahren soll einen Ausgleich von Unregelmäßigkeiten oder Toleranzen in problemloser Weise ermöglichen, wobei aufwendige Vorarbeiten vermieden werden sollen. Das Verfahren soll eine einfache Handhabung ermöglichen und keine besonderen Einstell­ maßnahmen, Vorarbeiten oder dergleichen vor oder bei der Durchführung der Schwei­ ßung erfordern.Proceeding from this, the object of the invention is to provide a method strike through which the disadvantages indicated above are avoided and which enables optimized welding with simple feasibility. The Procedures are designed to smooth out irregularities or tolerances in no problem Enabling way, while elaborate preparatory work should be avoided. The The procedure is intended to enable easy handling and no special settings measures, preparatory work or the like before or when carrying out the welding require ß.

Die Lösung dieser Aufgabe erfolgt gemäß den Merkmalen des Patentanspruchs 1.This object is achieved in accordance with the features of patent claim 1.

Das erfindungsgemäße Verfahren ermöglicht eine funktionssichere Verschweißung mit minimalem Aufwand. Durch die Vorerwärmung werden Toleranzen oder Ungleichmäßigkeiten zuverlässig ausgeglichen, so daß bei Beginn der eigent­ lichen Schweißung reproduzierbare Bedingungen vorliegen. Die Vorwärmung erfolgt mit wesentlich niedrigerer Heizenergie als während der Schweißung. Der Kunststoff wird in dieser Phase auf eine Temperatur gebracht, welche um einem vorgegebenen Betrag unter der Schmelztemperatur des Kunststoffes liegt. Die erfindungsgemäße Vorwärmung führt zu einer insbesondere radialen Ausdehnung des Rohres und Fittings, und zwar insbesondere des Rohres. Es ist von beson­ derer Bedeutung unter Berücksichtigung der Tatsache, daß der Draht der Heiz­ wicklung nicht von einem Kunststoffmantel umgeben und isoliert ist, sondern offen in der Innenfläche des Schweißfittings oder der Schweißmuffe angeordnet ist. Unter Berücksichtigung der Tatsache, daß der elektrisch leitende Draht nicht von einem Kunststoffmantel umgeben, sondern offen in der Innenfläche des Schweißfittings oder der Muffe angeordnet ist, bilden sich zwei Wärmefronten von in etwa gleicher Intensität zum einen im Fitting sowie im Kunststoffrohr aus und führen dazu, daß das Rohr über seine Wandstärke einen größeren Tempera­ turgradienten aufweist als der Fitting. Das hat zur Folge, daß die Ausdehnungs­ geschwindigkeit des Rohres größer ist als die des Fittings, so daß es zu einer Annäherung zwischen der Rohraußen- und Fittinginnenwand und somit zu einer Spaltverringerung kommt. Nach entsprechend langer Vorwärmzeit wird somit sichergestellt, daß die zu verschweißende Fläche des Kunststoffrohres unmittel­ bar an der Schweiß oder Heizwicklung anliegt.The method according to the invention enables a functionally reliable welding with minimal effort. Preheating causes tolerances  or irregularities reliably compensated, so that at the beginning of the actual reproducible conditions. The preheating takes place with significantly lower heating energy than during welding. Of the In this phase, plastic is brought to a temperature that is around one predetermined amount is below the melting temperature of the plastic. The Preheating according to the invention leads to a particularly radial expansion of the pipe and fittings, in particular the pipe. It is special their importance taking into account the fact that the wire of the heating winding is not surrounded and insulated by a plastic jacket, but instead arranged open in the inner surface of the welding fitting or welding socket is. Taking into account the fact that the electrically conductive wire is not surrounded by a plastic jacket, but open in the inner surface of the Weld fittings or the sleeve is arranged, two heat fronts are formed of approximately the same intensity on the one hand in the fitting and in the plastic pipe and cause the tube to have a larger tempera over its wall thickness has gradient than the fitting. As a result, the expansion speed of the pipe is greater than that of the fitting, so that it becomes a Approach between the pipe outer and fitting inner wall and thus to one Gap reduction is coming. After a correspondingly long preheating time ensured that the surface of the plastic pipe to be welded immediately bar against the welding or heating winding.

Nach der Vorerwärmung wird, zweckmäßig unmittelbar anschließend, umgehend die Schweißung selbst durchgeführt. Es sei festgehalten, daß auch eine kurze Unterbrechung zumindest solange nicht schadet, als ein maßgeblicher Tempera­ turausgleich zwischen der Temperatur des Fittings und des Rohres nicht erfolgt. Zur Vorgabe der Heizenergie während der Vorerwärmung können bei vorgegebe­ ner Spannung der Schweißstrom und bei vorgegebenem Strom die Spannung reduziert werden; ferner können Spannung und Strom zur Reduzierung der Heizenergie entsprechend abgesenkt vorgegeben werden. Die Reduzierung gegen­ über den Nennwerten zur Schweißung liegt zweckmäßig im Bereich zwischen 5 bis 20% < als die Nennwerte des Stromes und/oder der Spannung. Als besonders zweckmäßig hat sich eine Reduzierung von im wesentlichen 10% ergeben. Darüber hinaus wurde festgestellt, daß eine Vorerwärmung für eine Zeitdauer durchgeführt wird, welche in der Größenordnung der Zeitdauer für die eigentli­ che Schweißung liegt. Eine Abweichung der Vorerwärmzeit gegenüber der Schweißzeit im Bereich von +/- 50% lieferte gute Schweißergebnisse, wobei Abweichungen im Bereich von +/- 25% sich als besonders zweckmäßig herausge­ stellt haben. Das Verfahren gelangt in besonders zweckmäßiger Weise bei ver­ gleichsweise großen Rohren und Muffen zum Einsatz, und zwar für Nennweiten des Rohres von wenigstens 200 mm, insbesondere wenigstens 280 mm. Schließlich wurde erkannt, daß durch die Vorerwärmung der Kunststoff zumindest in der Nähe der Heizwendel auf eine Temperatur gebracht wird, welche um einen vorgegebenen Betrag niedriger ist als die Schmelztemperatur des Kunststoffes. Als besonders zweckmäßig hat sich gezeigt, wenn die Temperatur des Kunst­ stoffes zumindest in der Nähe der Heizwendel auf eine Temperatur gebracht wird, welche zwischen 5 bis 20% niedriger, zweckmäßig im wesentlichen 10% niedriger als die Schmelztemperatur des Kunststoffes ist. Für Polyäthylen, dessen Schmelztemperatur mit 110° angegeben ist, haben sich besonders gute Ergebnisse bei einer Vorerwärmung auf 100°C ergeben.After preheating, it is expedient to immediately immediately afterwards carried out the welding itself. It should be noted that a short one Interruption does not hurt at least as long as a significant tempera door compensation between the temperature of the fitting and the pipe was not carried out. To specify the heating energy during preheating can be specified at The voltage is the welding current and the voltage for a given current be reduced; furthermore voltage and current can be used to reduce the Heating energy can be specified accordingly lowered. The reduction against Above the nominal values for welding, it is expedient in the range between 5 up to 20% <as the nominal values of the current and / or the voltage. As special a reduction of essentially 10% has expediently resulted. In addition, it was found that preheating for a period of time is carried out, which is of the order of magnitude for the actual time  che weld lies. A deviation of the preheating time compared to the Welding time in the range of +/- 50% delivered good welding results, whereby Deviations in the range of +/- 25% have proven to be particularly expedient have put. The method is particularly useful for ver equally large pipes and sleeves are used for nominal sizes of the tube of at least 200 mm, in particular at least 280 mm. Finally was recognized that by preheating the plastic at least in the Near the heating coil is brought to a temperature which is around one predetermined amount is lower than the melting temperature of the plastic. It has been shown to be particularly useful if the temperature of the art brought to a temperature at least near the heating coil which is between 5 to 20% lower, expedient essentially 10% is lower than the melting temperature of the plastic. For polyethylene, whose Melting temperature is specified with 110 °, particularly good results have been obtained if preheated to 100 ° C.

Ein weiterer wichtiger Vorteil der erfindungsgemäßen Vorerwärmung besteht in der Tatsache, daß in den Spalt eindringende Flüssigkeit, insbesondere Wasser, gleichfalls erwärmt wird und verdunstet bzw. verdampft. Bisher mußten beson­ dere Maßnahmen vorgesehen werden, um das Eindringen von Flüssigkeit in den Spalt zwischen die zu verschweißenden Flächen des Fittings und der Rohrenden zu verhindern, da diese Flüssigkeit zur Blasenbildung und zu einer fehlerhafter Verschweißung führen kann. Besonders nachteilig war in der Praxis, daß hier­ durch verursachte Fehlstellen oftmals nicht sofort erkannt werden konnten und erst während des Betriebes, wenn die Rohre unter dem Druck des Mediums standen, Undichtheiten auftraten und sehr aufwendige kostenintensive Repara­ turmaßnahmen erforderten. Durch die Vorerwärmung werden diesbezügliche Risiken und/oder Montagefehler vermieden.Another important advantage of the preheating according to the invention is in the fact that liquid entering the gap, especially water, is also heated and evaporates or evaporates. So far, special Measures are provided to prevent the penetration of liquid into the Gap between the surfaces of the fitting to be welded and the pipe ends to prevent this liquid from blistering and becoming defective Welding can lead. In practice it was particularly disadvantageous that here often could not be immediately recognized due to defects and only during operation when the pipes are under the pressure of the medium stood, leaks occurred and very complex, costly repairs measures required. Preheating will make this possible Risks and / or assembly errors avoided.

In einer besonderen Ausgestaltung der Erfindung sind die für die Vorwärmung maßgeblichen Parameter, insbesondere Höhe des Stromes sowie die Dauer des Stromes, für das jeweilige Fitting bzw. die jeweilige Größe und/oder Material vorgegeben. Hierzu weißt das jeweilige Fitting vorzugsweise ein Speicherelement oder eine Kennkarte auf, mit welcher bevorzugt auch die eingangs erwähnten bekannten Schweißparameter gespeichert und zur Abfrage bereitgehalten sind.In a special embodiment of the invention, they are for preheating relevant parameters, in particular the amount of current and the duration of the Current, for the respective fitting or the respective size and / or material given. For this purpose, the respective fitting preferably has a storage element or an identification card, with which the ones mentioned above are also preferred Known welding parameters saved and kept ready for query are.

Claims (4)

1. Verfahren zum Elektroschweißen zur Herstellung einer Verbindung eines Rohres mit einem Fitting oder mit einer Muffe, welche ebenso wie das Rohr aus einem thermo­ plastischen, schweißbaren Kunststoff besteht und welche eine zum Schweißen mit Strom beaufschlagbare Spule oder Heizwendel aus Heizdraht enthält, wobei vor dem Schweißen eine Vorerwärmung des Kunststoffes durch Beaufschlagung der Spule oder Heizwendel mit einem Bruchteil der zum Schweißen erforderlichen Heizenergie durch­ geführt wird, um den Kunststoff auf eine Temperatur um einen vorgegebenen Betrag unterhalb seines Schmelzpunktes zu bringen, dadurch gekennzeichnet, daß Fittings oder Muffen verwendet werden, die keine Schrumpfreserve aufweisen, deren Heizdraht ohne Kunststoffummantelung offen in der Innenfläche angeordnet ist, und die entweder eine Wandstärke größer als die Wand­ stärke des Rohres oder eine Armierung aufweisen, und daß die zum Schweißen er­ forderliche Heizenergie zugeführt wird, bevor ein Temperaturausgleich zwischen dem Rohr und dem Fitting oder der Muffe erfolgt, so daß die Vorerwärmung zu einer stärke­ ren Ausdehnung des Rohres als des Fittings oder der Muffe und zum Anliegen des Rohres an dem Fitting oder der Muffe führt.1. A method for electric welding for producing a connection of a pipe with a fitting or with a sleeve, which, like the pipe, consists of a thermoplastic, weldable plastic and which contains a coil or heating coil made of heating wire that can be subjected to current for welding, whereby before Welding a preheating of the plastic is carried out by applying a fraction of the heating energy required for welding to the coil or heating coil in order to bring the plastic to a temperature by a predetermined amount below its melting point, characterized in that fittings or sleeves are used which have no shrink reserve, the heating wire without plastic sheathing is arranged open in the inner surface, and either have a wall thickness greater than the wall thickness of the tube or a reinforcement, and that the heating energy required for welding is supplied before a Te Temperature compensation takes place between the pipe and the fitting or the sleeve, so that the preheating leads to a stronger expansion of the pipe than the fitting or the sleeve and to the pipe against the fitting or the sleeve. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß während der Vor­ erwärmung der zugeführte Strom oder die anliegende Spannung gegenüber den Nenn­ werten während der Schweißung zwischen 5 bis 20% reduziert sind.2. The method according to claim 1, characterized in that during the pre heating of the supplied current or the applied voltage compared to the nominal values are reduced between 5 and 20% during welding. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die bei der Vor­ erwärmung erreichte Temperatur des Kunststoffes in der Nähe der Spule oder Heiz­ wendel um zwischen 5 bis 10%, insbesondere im wesentlichen 10% niedriger als die Schmelztemperatur des Kunststoffes ist.3. The method according to claim 1 or 2, characterized in that the in front heating reached temperature of the plastic near the coil or heating spiral between 5 to 10%, in particular essentially 10% lower than that Melting temperature of the plastic is. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Zeit zur Vorerwärmung in der Größenordnung der Zeit für die Durchführung der Schweiß­ ung vorgegeben ist.4. The method according to any one of claims 1 to 3, characterized in that the Preheating time on the order of time for performing the sweat is given.
DE4343449A 1993-12-20 1993-12-20 Process for electric welding Expired - Lifetime DE4343449C2 (en)

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DE4343449A DE4343449C2 (en) 1993-12-20 1993-12-20 Process for electric welding
CN94119350A CN1052441C (en) 1993-12-20 1994-12-17 Electric soldering method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19545317C2 (en) * 1995-12-05 2000-02-17 Huerner Gmbh Process and electric welding machine for automatic welding of heating coil fittings
DE102008044890B4 (en) 2008-08-29 2023-09-14 Stesatec Gmbh Catalyst for the catalytic gas phase oxidation of aromatic hydrocarbons to aldehydes, carboxylic acids and/or carboxylic anhydrides, in particular to phthalic anhydride, and process for producing such a catalyst
JP2016035260A (en) * 2014-07-31 2016-03-17 ヴィンタートゥール ガス アンド ディーゼル アーゲー Cylinder liner for reciprocating piston combustion engine
WO2016061691A1 (en) * 2014-10-24 2016-04-28 Shawcor Ltd. Apparatus and system for electro-fusion of polyethylene pipeline

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3600156A1 (en) * 1985-05-07 1986-11-13 Karl Schöngen KG Elektrobau und Kunststoffverarbeitung, 38229 Salzgitter Process for producing a welded joint between plastic pipes, means for carrying out this process and pipe joint
DE3540193C1 (en) * 1985-11-13 1987-04-23 Friedrichsfeld Gmbh Electric welding fitting or welding socket
DE2947166C1 (en) * 1978-04-28 1988-11-17 Werner Sturm Method and device for connecting thermoplastic pipe elements
DE3810795A1 (en) * 1988-03-30 1989-10-12 Huerner Gmbh ELECTRIC WELDING MACHINE FOR THE AUTOMATIC WELDING OF HEATING TURN FITTINGS

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE457823B (en) * 1985-10-22 1989-01-30 Ecopipe Innovation Ab MUFF JOINT FOR PLASTIC COATED INSULATED PIPES AND PROCEDURES FOR AAST COMMENT OF A MUFF JOINT

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2947166C1 (en) * 1978-04-28 1988-11-17 Werner Sturm Method and device for connecting thermoplastic pipe elements
DE3600156A1 (en) * 1985-05-07 1986-11-13 Karl Schöngen KG Elektrobau und Kunststoffverarbeitung, 38229 Salzgitter Process for producing a welded joint between plastic pipes, means for carrying out this process and pipe joint
DE3540193C1 (en) * 1985-11-13 1987-04-23 Friedrichsfeld Gmbh Electric welding fitting or welding socket
DE3810795A1 (en) * 1988-03-30 1989-10-12 Huerner Gmbh ELECTRIC WELDING MACHINE FOR THE AUTOMATIC WELDING OF HEATING TURN FITTINGS

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DE4343449A1 (en) 1995-06-22
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