Method and apparatus for electrofusing thermoplastic

• US 5,951,902 A
• Filed: 12/29/1997
• Issued: 09/14/1999
• Est. Priority Date: 12/29/1997
• Status: Expired due to Fees

• Current Assignee: Kerotest Manufacturing Corporation (Kerotest Industries, Inc.)
• Original Assignee: Kerotest Manufacturing Corporation (Kerotest Industries, Inc.)
• Inventors: Guthrie, Duane D., Pollum, Charles, Goodman, Bradley A.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): Patel, Vinod D.
• Application Number:
  US08/999,041
• Time in Patent Office: 624 Days
• Field of Search: 219/544, 219/543, 219/488, 219/490, 219/492, 219/497, 219/243, 156/499, 156/304.2
• US Class Current: 219/544
• CPC Class Codes: B29C 65/342 comprising at least a single wire, e.g. in the form of a winding
• CPC Class Codes: B29C 66/5221 for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
• 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 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/8618 being battery operated
• CPC Class Codes: B29C 66/8748 involving the use of warnings
• CPC Class Codes: B29C 66/91313 by measuring the voltage, i.e. the electric potential difference or electric tension
• CPC Class Codes: B29C 66/91317 by measuring the electrical resistance
• CPC Class Codes: B29C 66/91641 the heat or the thermal flux being non-constant over time
• 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 66/91655 by controlling or regulating the current intensity
• 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 66/94 by measuring or controlling 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: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence

Abstract

The present invention is directed to a method for creating an electrofused union between a plurality of thermoplastic members, with at least one of the members having an embedded electrically resistive element. The method includes the steps of generating a direct current voltage from a direct current power supply and transmitting the direct current voltage to the electrically resistive element. The present invention also contemplates an electrofusion system.

Claims

1. A method for creating an electrofused union between a plurality of thermoplastic members, wherein at least one of the members has an electrically resistive element embedded therein, comprising the steps of:

generating a direct current voltage from a direct current supply;

transmitting said direct current voltage to the electrically resistive element; and

regulating said direct current voltage transmitted to the electrically resistive element substantially at a predetermined direct current voltage.

2. The method of claim 1 wherein said predetermined direct current voltage is approximately 39.5 volts.

3. The method of claim 1 further comprising the step of charging said direct current power supply.

4. The method of claim 1 further comprising the step of ending the transmission of said direct current voltage in response to a control signal.

5. An electrofusion system, comprising:

a direct current power supply;

a fuse current circuit responsive to said direct current power supply for generating a direct current voltage;

at least one thermoplastic member, said member having an electrically resistive element; and

at least one electrical lead connected to enable dc current to flow between said fuse current circuit and said resistive element.

6. The system of claim 5 further comprising a charger circuit connected to said direct current power supply, said charger circuit for charging said direct current power supply.

7. The system of claim 6 wherein said charger circuit includes a trickle charger circuit.

8. The system of claim 6 wherein said charger circuit includes a ground fault interrupt circuit.

9. The system of claim 5 further comprising a control/display circuit connected to said fuse current circuit.

10. The system of claim 5 wherein said direct current power supply is a 48 volt power supply.

11. The system of claim 5 wherein said direct current power supply is comprised of four 12 volt batteries connected in series.

12. The system of claim 11 wherein said batteries are rechargeable batteries.

13. The system of claim 5 wherein said direct current voltage is approximately 39.5 volts.

17. The electrofusion system of claim 5, wherein said fuse current circuit includes a first circuit for determining a difference between said direct current voltage supplied to said resistive element and a predetermined direct current voltage.

18. The electrofusion system of claim 17, wherein said fuse current system includes a second circuit coupled to said first circuit for regulating said direct current voltage supplied to said resistive element substantially at said predetermined direct current voltage.

14. An electrofusion apparatus for electrofusing a thermoplastic member having an electrically resistive element to another thermoplastic member, comprising:

a direct current power supply;

a fuse current circuit responsive to said direct current power supply for generating a direct current voltage; and

at least one electrical lead connected to enable dc current to flow between said fuse current circuit and the resistive element.

19. The electrofusion apparatus of claim 14, wherein said fuse current circuit includes a first circuit for determining a difference between said direct current voltage supplied to said resistive element and a predetermined direct current voltage.

20. The electrofusion apparatus of claim 19, wherein said fuse current system includes a second circuit coupled to said first circuit for regulating said direct current voltage supplied to said resistive element substantially at said predetermined direct current voltage.

15. A method for creating an electrofused union between a plurality of thermoplastic members, wherein at least one of the members has an electrically resistive element embedded therein, comprising the steps of:

generating a pulse width modulated direct current signal from a direct current power supply;

regulating a direct current voltage based on said pulse width modulated direct current signal;

transmitting said direct current voltage to the electrically resistive element; and

adjusting said pulse width modulated direct current signal such that said regulated direct current voltage is substantially a predetermined direct current voltage.

16. An electrofusion system, comprising:

means for generating a direct current voltage from a direct current power supply;

means for transmitting said direct current voltage to an electrically resistive element embedded in a thermoplastic member; and

means for regulating said direct current voltage transmitted to said electrically resistive element at substantially a predetermined direct current voltage.