Method of inductively fusion joining plastic pipes

• US 5,908,575 A
• Filed: 05/16/1997
• Issued: 06/01/1999
• Est. Priority Date: 05/16/1997
• Status: Expired due to Term

• Current Assignee: Gas Technology Institute
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Smith, Cin, Perica, Goran, Bleske, Randy J., Kinney, Steve
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US08/857,876
• Time in Patent Office: 746 Days
• Field of Search: 219/633, 219/634, 219/643, 219/660, 219/661, 219/667, 219/110, 219/611, 285/288.1
• US Class Current: 219/633
• CPC Class Codes: B29C 65/34 using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
• CPC Class Codes: B29C 65/3468 characterised by the means for supplying heat to said heated elements which remain in the join, e.g. special electrical connectors of windings B29C65/3668 takes precedence
• CPC Class Codes: B29C 65/3476 being metallic
• CPC Class Codes: B29C 65/36 heated by induction
• CPC Class Codes: B29C 65/362 comprising at least a single wire, e.g. in the form of a winding
• CPC Class Codes: B29C 66/522 Joining tubular articles B29C66/53241 takes precedence
• CPC Class Codes: B29C 66/52241 with two right angles, e.g. for making T-shaped pieces
• CPC Class Codes: B29C 66/5229 involving the use of a socket
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/841 Machines or tools adaptable for making articles of different dimensions or shapes or for making joints of different dimensions
• CPC Class Codes: B29C 66/8618 being battery operated
• CPC Class Codes: B29C 66/8748 involving the use of warnings
• CPC Class Codes: B29C 66/9121 by measuring the temperature
• CPC Class Codes: B29C 66/91651 by controlling or regulating the heat generated by Joule heating or induction heating
• CPC Class Codes: B29C 66/91653 by controlling or regulating the voltage, i.e. the electric potential difference or electric tension
• CPC Class Codes: B29C 66/919 characterised by specific temperature, heat or thermal flux values or ranges specific electrical resistance values B29C66/81262
• CPC Class Codes: B29C 66/91921 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
• CPC Class Codes: B29C 66/944 by controlling or regulating the time
• CPC Class Codes: B29C 66/961 involving a feedback loop mechanism, e.g. comparison with a desired value
• CPC Class Codes: B29C 66/9672 : involving special data inputs, e.g. involving barcodes, RFID tags
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene

Abstract

A method and apparatus for fusion joining polyethylene pipe. A power source supplies an input power to an input of a power supply. The input power has generally constant current and is converted to an output power at a relatively high frequency. The relatively high frequency output power is delivered to an installation tool. The output power delivered to the installation tool is controlled. The output power can be controlled as a function of ambient temperature surrounding the installation tool.

Claims

1. A method of fusion joining polyethylene pipe with a coupling using an induction heating tool, the method comprising the steps of:

supplying an input power from a power source to an input of a power supply;

converting the input power to an output power at a high frequency;

delivering the converted high frequency output power to the induction heating tool at a generally constant voltage;

controlling the delivery of the output power using a controller sensing a heat demand of the induction heating tool; and

operating the induction heating tool with the high frequency output power and generating an induction fusion between the coupling and the polyethylene pipe.

2. A method according to claim 1 wherein said power source is an AC source which supplies the input power at a low frequency in a range from about zero Hz to about 75 Hz.

3. A method according to claim 1 wherein said power source is a DC source which supplies the input power.

4. A method according to claim 1 wherein the output power at the high frequency is in a range from about 380 kHz to about 420 kHz.

5. A method according to claim 1 wherein the output power is delivered to a plurality of leads electrically connected to the induction heating tool.

6. A method according to claim 1 wherein the output power is delivered to an application tool for energizing the induction heating tool.

7. A method according to claim 1 wherein the input power is supplied at a generally constant current.

8. A method according to claim 1 wherein the delivery of the output power is controlled as a function of an ambient temperature sensed near a location of the induction heating tool.

9. A method according to claim 1 wherein a battery supplies the input power as a generally constant voltage DC waveform.