Connection component for together plastic elements by thermal welding

• US 5,141,580 A
• Filed: 11/27/1990
• Issued: 08/25/1992
• Est. Priority Date: 11/29/1989
• Status: Expired due to Term

• Current Assignee: Gdf Suez
• Original Assignee: Gaz de France
• Inventors: Dufour, Denis, Fortin, Francois
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Maki, Steven D.
• Application Number:
  US07/618,391
• Time in Patent Office: 637 Days
• Field of Search: 156/273.9, 156/274.2, 156/304.2, 156/304.6, 156/158, 156/294, 285/21, 219/497, 219/517, 219/535, 219/544, 219/548, 219/552, 219/549, 219/528, 219/522
• US Class Current: 156/158
• CPC Class Codes: B29C 65/344 being a woven or non-woven fabric or being a mesh
• CPC Class Codes: B29C 65/348 with a polymer coating
• CPC Class Codes: B29C 66/112 Single lapped joints
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/131 Single flanged joints, i.e. one of the parts to be joined being rigid and flanged in the joint area
• CPC Class Codes: B29C 66/3242 on the inside of a tubular or hollow article
• 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 66/71 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 66/91313 by measuring the voltage, i.e. the electric potential difference or electric tension
• CPC Class Codes: B29C 66/91315 by measuring the current intensity
• CPC Class Codes: B29C 66/91411 of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• 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 66/91921 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 66/91931 in explicit relation to the fusion temperature or melting point of the material of one of the parts to be joined
• CPC Class Codes: B29C 66/949 characterised by specific time values or ranges
• CPC Class Codes: B29C 66/9592 : in explicit relation to another variable, e.g. X-Y diagrams
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2023/18 : Polymers of hydrocarbons having four or more carbon atoms, e.g. polymers of butylene, e.g. PB, i.e. polybutylene
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: F16L 47/03 : Welded joints with an electrical resistance incorporated in the joint

Abstract

The invention relates to a connection component equipped with an electrical resistor for the welding of elements made of heat-fusing plastic. According to the invention, the resistor takes the form of a single wire coated with an electrically insulating layer and having points of intersection, the coating layer fusing at a temperature between the fusion temperature of the components to be joined together and their temperature of thermal damage, so that short-circuits are generated on the wire and so that the stopping of the supply of current to the latter is commanded. The invention is used particularly for the thermal welding of polyethylene pipes used in the gas industry.

Claims

1. A method for electrically welding thermoplastic piping components, wherein facing surfaces of the components to be welded are juxtaposed and heated to fusion by a single-conductor electrical resistance heater carried by one of said components, comprising the steps of:

a. covering said single-conductor resistance heater with an electrically insulating material, said insulating material having a fusion temperature between a fusion temperature of said thermoplastic piping components and a temperature at which said piping components suffer thermal damage;

b. disposing said single-conductor resistance heater in a manner providing a plurality of overlapping points where said single-conductor resistance heater intersects itself, said points forming a corresponding number of potential short-circuit points;

c. providing electrical current to said resistance heater until said insulating material fuses at at least one of said intersection points, causing at least one short circuit in said resistance heater; and

d. interrupting said electrical current upon an occurrence of said at least one short circuit.

2. In a connector for connecting piping components being formed, at least in part, of a heat-fusible thermoplastic material, said connector being formed, at least in part, of a heat-fusible thermoplastic material and carrying at least one single-conductor electrical resistance heater adapted for heating said thermoplastic material of said connector to effect weldment thereof to said thermoplastic material of said piping components, wherein the improvement comprises:

said resistance heater including a conductor covered with a coating of an electrically insulating material;

said insulating material having a fusion temperature higher than a fusion temperature of said thermoplastic material of said piping components and lower than a temperature at which the thermoplastic portion of said piping components suffer thermal damage; and

said conductor being disposed in a manner providing a plurality of overlapping points where said conductor intersects itself, whereby, when said conductor is heated above said fusion temperature of said insulating material, said conductor establishes electrical contact at at least one of said overlapping points.

3. A connector according to claim 2, wherein said conductor is disposed in the form of a series of interlaced loops.

4. A connector according to claim 2, wherein said insulating material has a fusion temperature in the range of about 300 to about 350 degrees C.

5. A connector according to claim 2, wherein said conductor is formed of copper wire having a diameter between approximately 0.3 mm. and 0.5 mm. and a resistance of between approximately 1 and 10 ohms.

6. A connector according to claim 2, wherein said insulating material is a polyesterimide.

7. A connector according to claim 2, further including:

means for supplying electrical current to said resistance heater;

means for detecting a short circuit in said resistance heater; and

means for interrupting said electrical current upon an occurrence of a short circuit.

8. A connector according to claim 2, wherein said resistance heater forms a network with a cylindrical shape.