CH437755A - Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistor - Google Patents
Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistorInfo
- Publication number
- CH437755A CH437755A CH1638265A CH1638265A CH437755A CH 437755 A CH437755 A CH 437755A CH 1638265 A CH1638265 A CH 1638265A CH 1638265 A CH1638265 A CH 1638265A CH 437755 A CH437755 A CH 437755A
- Authority
- CH
- Switzerland
- Prior art keywords
- welding device
- heating
- temperature
- welding
- temperature sensor
- Prior art date
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"
- B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
- B29C65/342—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint comprising at least a single wire, e.g. in the form of a winding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
- B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
- B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- 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
- B29C66/91—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
- B29C66/9141—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
- B29C66/91431—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 the temperature being kept constant over time
-
- 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
- B29C66/96—Measuring or controlling the joining process characterised by the method for implementing the controlling of the joining process
- B29C66/961—Measuring or controlling the joining process characterised by the method for implementing the controlling of the joining process involving a feedback loop mechanism, e.g. comparison with a desired value
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device
- G05D23/1909—Control of temperature characterised by the use of electric means using an analogue comparing device whose output amplitude can only take two discrete values
-
- 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
- B29C66/94—Measuring or controlling the joining process by measuring or controlling the time
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
Description
Elektronisch gesteuertes Schweissgerät zum Verbinden von Rohren und Formstücken aus schweissbarem Kunststoff mittels eines einen elektrischen Heizwiderstand aufweisenden
Verbindungsstückes
Zum Verbinden von Rohren und Formstücken aus gut schweissbaren, thermoplastischen Kunststoffen, wie Polyäthylen, Polystyrol, Polyamid usw., wie sie z. B. auf dem Gebiet der Hausentwässerung Verwendung finden, sind elektrisch und elektronisch gesteuerte Schweissgeräte bekannt. Es werden dabei als Schweissmuffe bezeichnete Verbindungsstücke verwendet, welche einen zwischen den zu verbindenden Teilen befindlichen Widerstandsdraht aufweisen, welcher elektrisch aufzuheizen ist, um die für die Verbindung erforderliche Schweisswärme aufzubringen.
Die Stromlieferung ist dabei an die Grösse der Verbindung anzupassen und wird über eine an der Schweissmuffe vorhandene Steckverbindung vom Schweissgerät gesteuert, welches am öffentlichen Stromversorgungsnetz angeschlossen wird.
Bekannte Geräte dieser Art enthalten einen Schweiss-, Regel- und Trenntransformator, und die der Schweissmuffe zugeführte Heizenergie ist durch den Widerstand des Heizdrahtes, den Heizstrom und die an einem Zeitschaltkreis einstellbare Heizdauer gegeben.
Solche Geräte erweisen sich allerdings als ungeeignet, da Schwankungen der Netzspannung und Widerstands änderungen des Heizdrahtes nicht berücksichtigt werden und deshalb die von Fall zu Fall aufgebrachte Schweisswärme nicht in den für eine gute Verbindung erforderlichen engen Grenzen gehalten wird.
Bessere Resultate ergeben sich mit Schweissgeräten, welche das Produkt 12.t auf einem bestimmten, der Muffengrösse angepassten Wert konstant halten und Schwankungen der Netzspannung sowie des Heizdraht Widerstandes kompensieren. Zu dieser Kategorie gehören auch Schweissgeräte, welche keinen Leistungstransformator aufweisen und bei denen der Verbraucher (Schweissmuffe) über ein elektronisches Leistungssteuerelement direkt mit dem Netz zu verbinden ist.
Dank Verwendung solcher Steuerelemente (Thyratron oder steuerbarer Halbleiter-Gleichrichter) lassen sich besonders handliche Geräte von niedrigem Gewicht und geringem Platzbedarf bauen. Die besondere Arbeitsweise solcher Steuerelemente zur Dosierung der Heizleistung (Veränderung des Stromflusswinkels durch Phasenverschiebung des Zündimpulses, sogenannte Phasenanschnittsteuerung) ermöglicht auch eine kontinuierliche Leistungsanpassung und geringere Verluste.
Aber auch die Einhaltung eines bestimmten Energiebetrages entsprechend dem Produkt 12.t mit den er wähnten Geräten kann nicht unbedingt eine gute Schweissverbindung gewährleisten. Es ist zu bedenken, dass bei einer Schweisstemperatur, die je nach Material zwischen etwa 200 und 2600 C liegt, die erreichten Temperaturwerte von Verbindung zu Verbindung um nicht mehr als etwa 200 C vom Idealwert abweichen dürfen. Vor allem im Baustellenbetrieb werden jedoch die Schweissungen unter den verschiedensten Bedingungen vorgenommen, beispielsweise kann die Ausgangstemperatur des Materials im Sommer etwa 400 und im Winter -100 C betragen, und verschiedene Abstrahlungsbedingungen oder Luftbewegungen können den Aufheizvorgang der Schweissmuffe recht unterschiedlich beeinflussen.
Die vorliegende Erfindung bezweckt die Schaffung eines Schweissgerätes, welches von den erwähnten Mängeln frei ist und auch unter erschwerten Bedingungen, wie etwa beim Einsatz auf Baustellen, gleichbleibend gute Schweissverbindungen sicherstellt. Die Erfindung betrifft demnach ein für Netz ans chluss bestimmtes, elektronisch gesteuertes Schweissgerät zum Verbinden von Rohren und Formstücken aus schweissbarem Kunststoff mittels eines einen elektrischen Heizwiderstand aufweisenden Verbindungsstückes, wobei der Heizwiderstand über eine steuerbare Leistungssteuereinrichtung direkt an das Netz anschliessbar ist.
Das Schweissgerät gemäss der Erfindung ist gekennzeichnet durch einen die genannte Leistungssteuereinrichtung enthaltenden Regelkreis zur Konstanthaltung des Heizstromes während des Aufheizens des Heizwiderstandes, sowie durch einen von der Temperatur des Verbin dungsstückes abhängigen Temperaturfühler zur selbst tätigen Unterbrechung des Aufheizens bei Erreichen einer vorbestimmten Schweisstemperatur.
Mit einer solchen Anordnung wird ermöglicht, dass einerseits am Gerät ein der jeweiligen Grösse der Schweissmuffe angepasster Leistungsfluss einstellbar ist, die pro Verbindung aufgebrachte Energiemenge jedoch nicht starr vorbestimmt, sondern von der sich an der Verbindungsstelle einstellenden Temperatur abhängig ist.
Ein Ausführungsbeispiel der Erfindung wird nachstehend im Zusammenhang mit der Zeichnung erläutert, welche das Blockschaltbild eines Schweissgerätes mit angeschlossener Schweissmuffe darstellt.
Das bei 15 an das Wechselstromnetz anzuschliessende Schweissgerät ist wie folgt aufgebaut: Der vom Schweiss- bzw. Heizstrom durchflossene Arbeitsstromkreis des Gerätes enthält einen Istwertgeber 1, vorzugsweise einen Stromwandler, welcher die Grösse des Heizstromes feststellt, einen Leistungssteuerkreis 2 sowie einen Relaiskreis 3. An diesen Arbeitskreis ist die jeweilige Schweissmuffe 4 über eine Steckverbindung 16 anzuschliessen. Der Kreis 2 enthält ein den Mittelwert des Heizstromes bestimmendes Leistungssteuerelement, vorzugsweise einen steuerbaren Halbleiter-Gleichrichter, welcher nach dem bekannten Prinzip der Phasenanschnittsteuerung arbeitet.
Die erwähnte Leistungssteuereinrichtung bildet das Stellglied eines Regelkreises, der sich aus dem Istwertgeber 1, einem Regelverstärker 6, einem Impulsübertragerkreis 7 und dem erwähnten Kreis 2 zusammensetzt und grundsätzlich den Heizstrom während des Aufheizvorganges konstant hält. Ein mit dem Regelverstärker 6 verbundener Sollwertgeber 11 ermöglicht, die Grösse dieses Stromes einmalig einzustellen. Das Gerät arbeitet demnach mit einem eingeprägten Heizstrom, und es können Schweissmuffen unterschiedlicher Grösse angeschlossen werden, deren Heizdraht-Widerstand z. B. zwischen 5 und 35 Ohm abgestuft ist. Mit dem Regelverstärker 6 ist ferner ein Nulldurchgangs-Synchronisierkreis 5 verbunden, welcher die Erzeugung der Zündimpulse im Takt der Netzfrequenz steuert.
Um das Aufheizen der Verbindungsstelle im geeigneten Augenblick zu unterbrechen, ist ein Temperaturfühler 9 vorgesehen, welcher an einen Uberwachungs- kreis 8 angeschlossen ist. Der Temperaturfühler 9 wird vorzugsweise gleichzeitig mit der Herstellung der Steckverbindung 16 in die geeignete Lage zur Temperaturmessung an der Schweissmuffe 4 gebracht. Als Temperaturfühler ist im vorliegenden Fall ein Thermoelement verwendet, dessen Thermospannung ein Mass für die Temperatur der Verbindungsstelle darstellt; es ist jedoch auch die Verwendung anderer temperaturabhän gi ger Schaltelemente (Bimetallschalter, Heissleiterwiderstand usw.) denkbar. Der Überwachungskreis 8 ist zur Einwirkung auf den Regelkreis an den Impulsübertragerkreis 7 angeschlossen und steht ferner unter dem Einfluss eines Startkreises 12.
Da die Schweissmuffe 4 zum direkten Anschluss an das Netz über den Arbeitskreis bestimmt ist, sind besondere Schaltungsmassnahmen getroffen, um den Benützer des Gerätes vor Berührung mit der Netzspannung zu schützen, solange die Steckverbindung 16 noch nicht hergestellt ist. Zu diesem Zweck wird mittels einer von einem internen Speisekreis 10 gelieferten Schutzspannung der Widerstand über den Steckerstiften kontrolliert. Liegt dieser Widerstand nicht in der Grössenordnung der Schweissmuffen, so wird ein Zuschalten des Heizstromes und damit das Anschalten der Netzspannung an den Ausgangsstecker im Relaiskreis 3 verhindert.
Erst nach ordnungsgemässem Anschluss der Schweissmuffe wird die Stromlieferung freigegeben, und nach Betätigung einer Starttaste im Startkreis 12 beginnt der Heizstrom nach Massgabe des erwähnten Regelkreises zu fliessen; das Ausgangsrelais hält sich durch den nun fliessenden Heizstrom selbst. Damit beginnt die Aufheizung der Verbindungsstelle mit stabil gehaltenem Heizstrom. Der entsprechende Temperatur anstieg wird vom Fühler 9 festgestellt und in den Überwachungskreis 8 gemeldet. Sobald die vorbestimmte, zur einwandfreien Verbindung des Kunststoffmaterials erforderliche Temperatur erreicht ist, blockiert der Überwachungskreis 8 die Übertragung der Zündimpulse im Kreis 7, wodurch der Heizstrom unterbrochen wird und das Ausgangsrelais abfällt.
Der einmalig einzustellende Bezugswert für die erforderliche Schweisstemperatur, mit dem die ansteigende Thermospannung des Fühlers 9 im Überwachungskreis 8 verglichen wird, lässt sich vorzugsweise ebenfalls am Sollwertgeber 11 einstellen.
Das beschriebene Schweissgerät bietet Gewähr für die Herstellung von Schweissstellen mit gleichbleibend guter Qualität. Der auf die Grösse der Verbindung abgestimmte und während des Aufheizens konstant gehaltene Schweissstrom ermöglicht die gewünschte gleichmässige Temperaturverteilung über die gesamte Verbindung ohne örtliche Überhitzungen. Da ferner für die Beendigung des Aufheizens direkt auf die erreichte Temperatur an der Schweissstelle abgestellt wird, kann sich die insgesamt zugeführte Energie den unterschiedlichen Ausgangsbedingungen oder Umgebungseinflüssen anpassen, womit eine Verfälschung der Ergebnisse infolge solcher Einflüsse praktisch ausgeschlossen ist.
Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of an electrical heating resistor
Connector
For connecting pipes and fittings made of easily weldable, thermoplastic materials such as polyethylene, polystyrene, polyamide, etc., as they are, for. B. in the field of house drainage use, electrically and electronically controlled welding devices are known. In this case, connecting pieces called welding sleeves are used, which have a resistance wire located between the parts to be connected, which is electrically heated in order to apply the welding heat required for the connection.
The power supply has to be adapted to the size of the connection and is controlled by the welding device via a plug connection on the welding socket, which is connected to the public power supply network.
Known devices of this type contain a welding, regulating and isolating transformer, and the heating energy supplied to the welding socket is given by the resistance of the heating wire, the heating current and the heating duration which can be set on a timer circuit.
Such devices prove to be unsuitable, however, since fluctuations in the mains voltage and changes in resistance of the heating wire are not taken into account and therefore the welding heat applied from case to case is not kept within the narrow limits required for a good connection.
Better results are obtained with welding devices which keep the 12.t product constant at a certain value adapted to the socket size and compensate for fluctuations in the mains voltage and the resistance of the heating wire. This category also includes welding devices that do not have a power transformer and where the consumer (welding socket) is to be connected directly to the mains via an electronic power control element.
Thanks to the use of such control elements (thyratron or controllable semiconductor rectifier), particularly handy devices with low weight and little space requirements can be built. The special mode of operation of such control elements for metering the heating power (change of the current flow angle by phase shifting the ignition pulse, so-called phase control) also enables continuous power adjustment and lower losses.
However, compliance with a certain amount of energy corresponding to the 12.t product with the devices mentioned cannot necessarily guarantee a good welded connection. It should be remembered that at a welding temperature that is between about 200 and 2600 C, depending on the material, the temperature values achieved from connection to connection must not deviate from the ideal value by more than 200 C. However, especially in construction site operations, the welds are carried out under a wide variety of conditions, for example the starting temperature of the material can be around 400 C in summer and -100 C in winter, and different radiation conditions or air movements can affect the heating process of the welding socket in very different ways.
The present invention aims to create a welding device which is free from the deficiencies mentioned and which ensures consistently good welded connections even under difficult conditions, such as when used on construction sites. The invention accordingly relates to an electronically controlled welding device intended for network connection for connecting pipes and fittings made of weldable plastic by means of a connecting piece having an electrical heating resistor, the heating resistor being connectable directly to the network via a controllable power control device.
The welding device according to the invention is characterized by a control circuit containing said power control device to keep the heating current constant while the heating resistor is being heated, and by a temperature sensor dependent on the temperature of the connector for automatically interrupting heating when a predetermined welding temperature is reached.
With such an arrangement it is possible on the one hand to set a power flow adapted to the respective size of the welding socket on the device, but the amount of energy applied per connection is not rigidly predetermined, but rather depends on the temperature that is set at the connection point.
An embodiment of the invention is explained below in connection with the drawing, which shows the block diagram of a welding device with a connected welding socket.
The welding device to be connected to the alternating current network at 15 is constructed as follows: The working circuit of the device through which the welding or heating current flows contains an actual value transmitter 1, preferably a current transformer, which determines the magnitude of the heating current, a power control circuit 2 and a relay circuit 3 Working group, the respective welding socket 4 is to be connected via a plug connection 16. The circuit 2 contains a power control element which determines the mean value of the heating current, preferably a controllable semiconductor rectifier which operates according to the known principle of phase control.
The mentioned power control device forms the actuator of a control circuit, which is composed of the actual value transmitter 1, a control amplifier 6, a pulse transmitter circuit 7 and the mentioned circuit 2 and basically keeps the heating current constant during the heating process. A setpoint generator 11 connected to the control amplifier 6 makes it possible to set the magnitude of this current once. The device therefore works with an impressed heating current, and welding sleeves of different sizes can be connected, whose heating wire resistance z. B. is graded between 5 and 35 ohms. A zero crossing synchronization circuit 5 is also connected to the control amplifier 6 and controls the generation of the ignition pulses in time with the mains frequency.
In order to interrupt the heating of the connection point at a suitable moment, a temperature sensor 9 is provided which is connected to a monitoring circuit 8. The temperature sensor 9 is preferably brought into the suitable position for temperature measurement on the welding socket 4 at the same time as the plug connection 16 is made. In the present case, a thermocouple is used as the temperature sensor, the thermal voltage of which is a measure of the temperature of the connection point; however, the use of other temperature-dependent switching elements (bimetal switch, hot conductor resistor, etc.) is also conceivable. The monitoring circuit 8 is connected to the pulse transmitter circuit 7 to act on the control circuit and is also under the influence of a start circuit 12.
Since the welding socket 4 is intended for direct connection to the network via the working group, special circuit measures are taken to protect the user of the device from contact with the mains voltage as long as the plug connection 16 has not yet been established. For this purpose, the resistance across the connector pins is controlled by means of a protective voltage supplied by an internal supply circuit 10. If this resistance is not of the order of magnitude of the welding sockets, then switching on the heating current and thus switching on the mains voltage to the output connector in relay circuit 3 is prevented.
The current supply is only released after the welding socket has been properly connected, and after actuation of a start button in the start circuit 12, the heating current begins to flow in accordance with the aforementioned control circuit; the output relay maintains itself through the heating current that is now flowing. This starts the heating of the connection point with the heating current kept stable. The corresponding temperature rise is detected by the sensor 9 and reported to the monitoring circuit 8. As soon as the predetermined temperature required for proper connection of the plastic material is reached, the monitoring circuit 8 blocks the transmission of the ignition pulses in circuit 7, whereby the heating current is interrupted and the output relay drops out.
The reference value to be set once for the required welding temperature, with which the rising thermal voltage of the sensor 9 in the monitoring circuit 8 is compared, can preferably also be set on the setpoint generator 11.
The welding device described offers a guarantee for the production of welds with consistently good quality. The welding current, which is matched to the size of the connection and kept constant during the heating process, enables the desired uniform temperature distribution over the entire connection without local overheating. Furthermore, since the temperature reached at the welding point is used directly for the termination of the heating, the total energy supplied can be adapted to the different starting conditions or environmental influences, which means that any falsification of the results due to such influences is practically impossible.
Claims (1)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH1638265A CH437755A (en) | 1965-11-29 | 1965-11-29 | Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistor |
| DK613466A DK124383B (en) | 1965-11-29 | 1966-11-25 | Welding apparatus with electronic current regulating apparatus for use in joining pipe fittings of weldable plastic by electric resistance heating. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH1638265A CH437755A (en) | 1965-11-29 | 1965-11-29 | Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CH437755A true CH437755A (en) | 1967-06-15 |
Family
ID=4416874
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CH1638265A CH437755A (en) | 1965-11-29 | 1965-11-29 | Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistor |
Country Status (2)
| Country | Link |
|---|---|
| CH (1) | CH437755A (en) |
| DK (1) | DK124383B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3005078A1 (en) * | 1979-03-19 | 1980-10-02 | Von Roll Ag | ELECTRICALLY WELDABLE PLUG IN PLASTIC |
| EP0082451A1 (en) * | 1981-12-23 | 1983-06-29 | Georg Fischer Aktiengesellschaft | Process and apparatus for welding pipe elements |
| EP0129505A2 (en) * | 1983-06-15 | 1984-12-27 | Geberit AG | Control circuit for switching off the heating current of a current-heated plastics welding sleeve |
| FR2555936A1 (en) * | 1983-12-19 | 1985-06-07 | Toutelectric | METHOD FOR CONTROLLING THE WELDING TIME |
| FR2572327A2 (en) * | 1983-12-19 | 1986-05-02 | Toutelectric Sam | Device for controlling the welding time |
| EP0297185A1 (en) * | 1985-11-08 | 1989-01-04 | R.W. LYALL & COMPANY, INC. | Method and apparatus for making fused connections |
| US4943706A (en) * | 1988-04-18 | 1990-07-24 | R. W. Lyall & Company, Inc. | Method and apparatus for fusing thermoplastic materials |
-
1965
- 1965-11-29 CH CH1638265A patent/CH437755A/en unknown
-
1966
- 1966-11-25 DK DK613466A patent/DK124383B/en unknown
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3005078A1 (en) * | 1979-03-19 | 1980-10-02 | Von Roll Ag | ELECTRICALLY WELDABLE PLUG IN PLASTIC |
| EP0082451A1 (en) * | 1981-12-23 | 1983-06-29 | Georg Fischer Aktiengesellschaft | Process and apparatus for welding pipe elements |
| US4642154A (en) * | 1981-12-23 | 1987-02-10 | Georg Fischer Aktiengesellschaft | Method and apparatus for welding conduits |
| EP0129505A2 (en) * | 1983-06-15 | 1984-12-27 | Geberit AG | Control circuit for switching off the heating current of a current-heated plastics welding sleeve |
| EP0129505A3 (en) * | 1983-06-15 | 1986-02-05 | Geberit Ag | Control circuit for switching off the heating current of a current-heated plastics welding sleeve |
| FR2555936A1 (en) * | 1983-12-19 | 1985-06-07 | Toutelectric | METHOD FOR CONTROLLING THE WELDING TIME |
| EP0149410A2 (en) * | 1983-12-19 | 1985-07-24 | INNOVATION GENERALE en abrégé "INNOGE" | Method of controlling welding time |
| EP0149410A3 (en) * | 1983-12-19 | 1985-12-18 | Toutelectric | Method of controlling welding time |
| FR2572327A2 (en) * | 1983-12-19 | 1986-05-02 | Toutelectric Sam | Device for controlling the welding time |
| EP0297185A1 (en) * | 1985-11-08 | 1989-01-04 | R.W. LYALL & COMPANY, INC. | Method and apparatus for making fused connections |
| US4943706A (en) * | 1988-04-18 | 1990-07-24 | R. W. Lyall & Company, Inc. | Method and apparatus for fusing thermoplastic materials |
Also Published As
| Publication number | Publication date |
|---|---|
| DK124383B (en) | 1972-10-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| DE4003984C2 (en) | Control device for an electric rice cooker | |
| DE1926250A1 (en) | Method and device for measurement by determining the temperature of a thermosensitive element heated by the Joule effect | |
| CH437755A (en) | Electronically controlled welding device for connecting pipes and fittings made of weldable plastic by means of a connector with an electrical heating resistor | |
| DE102010009523B4 (en) | Device for controlling the temperature of an electric heating wire when cutting bodies to be separated by heat | |
| CH653611A5 (en) | METHOD AND DEVICE FOR WELDING LINE ELEMENTS. | |
| DE3390260T1 (en) | System for heating a fluid hose | |
| DE2213760B1 (en) | DEVICE FOR MEASURING THE AMOUNTS OF HEAT USED IN HOT WATER HEATING SYSTEMS | |
| DE2516613A1 (en) | Electronic integration calorimeter - for water flowing through air conditioner, represents temp. difference and flow rate by pulse signals | |
| DE2065154A1 (en) | Control device for feeding a consumer. Eliminated from: 2003389 | |
| DE1279813B (en) | Two-point controller with a thyratron as an actuator | |
| EP0202401B1 (en) | Heating device | |
| DE2945196C1 (en) | Device for controlling the welding energy when connecting pipe elements made of weldable plastic | |
| DE202021105789U1 (en) | Electric heating product | |
| DE2102787A1 (en) | Process for achieving an almost constant final temperature when connecting plastic pipes or molded pieces by means of electrically heatable fittings and control unit for carrying out the process | |
| DE2342264C3 (en) | Temperature controller for a three-phase heated device | |
| EP0048772B1 (en) | Hot-air device for desoldering, soldering, shrinking and the like | |
| DE2835750C2 (en) | Process for electrical resistance welding or soldering with measurement of the electrode temperature | |
| DE2206189B2 (en) | Electrically heatable heating mirror for welding workpieces made of thermoplastic material | |
| DE2260143C3 (en) | Water heater | |
| DE2557426C3 (en) | Electric temperature controller | |
| DE3900284A1 (en) | Method for determining the water throughput through an electrically heated instantaneous water heater | |
| DE3623087A1 (en) | ELECTRICALLY OPERATED HEATING DEVICE | |
| DE1538666C3 (en) | Circuit for controlling or regulating the current for consumers | |
| DE2109470A1 (en) | Soldering iron | |
| DE2518758A1 (en) | Thermostat with temp. sensor and switch - has LV electronic circuit fed with mains reactive current for sensor evaluation |