Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/02—Induction heating
  • H05B6/36—Coil arrangements
  • H05B6/362—Coil arrangements with flat coil conductors
• • 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
  • B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
  • B29C65/20—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools with direct contact, e.g. using "mirror"
  • B29C65/2007—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools with direct contact, e.g. using "mirror" characterised by the type of welding mirror
  • B29C65/2015—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools with direct contact, e.g. using "mirror" characterised by the type of welding mirror being a single welding mirror comprising several separate heating surfaces in different planes, e.g. said heating surfaces having different temperatures
• • 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
  • B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
  • B29C65/24—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools characterised by the means for heating the tool
  • B29C65/30—Electrical means
  • B29C65/32—Induction
• • 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
  • B29C65/78—Means for handling the parts to be joined, e.g. for making containers or hollow articles, e.g. means for handling sheets, plates, web-like materials, tubular articles, hollow articles or elements to be joined therewith; Means for discharging the joined articles from the joining apparatus
  • B29C65/7841—Holding or clamping means for handling purposes
• • 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
  • B29C66/004—Preventing sticking together, e.g. of some areas of the parts to be joined
  • B29C66/0042—Preventing sticking together, e.g. of some areas of the parts to be joined of the joining tool and 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
  • B29C66/01—General aspects dealing with the joint area or with the area to be joined
  • B29C66/05—Particular design of joint configurations
  • B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
  • B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
  • B29C66/114—Single butt joints
  • B29C66/1142—Single butt to butt joints
• • 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
  • B29C66/5221—Joining tubular articles for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
  • B29C66/812—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
  • B29C66/8122—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
  • B29C66/812—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
  • B29C66/8126—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the composition, by the structure, by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps characterised by the intensive physical properties or by the optical properties of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
  • B29C66/81261—Thermal properties, e.g. thermal conductivity, thermal expansion coefficient
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
  • B29C66/818—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps
  • B29C66/8182—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the thermal insulating constructional aspects
  • B29C66/81821—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the thermal insulating constructional aspects of the welding jaws
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/81—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps
  • B29C66/818—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps
  • B29C66/8187—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the electrical insulating constructional aspects
  • B29C66/81871—General aspects of the pressing elements, i.e. the elements applying pressure on the parts to be joined in the area to be joined, e.g. the welding jaws or clamps characterised by the cooling constructional aspects, or by the thermal or electrical insulating or conducting constructional aspects of the welding jaws or of the clamps ; comprising means for compensating for the thermal expansion of the welding jaws or of the clamps characterised by the electrical insulating constructional aspects of the welding jaws
• • 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
  • B29C66/80—General aspects of machine operations or constructions and parts thereof
  • B29C66/84—Specific machine types or machines suitable for specific applications
  • B29C66/861—Hand-held tools
• • 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
  • B29C66/5224—Joining tubular articles for forming fork-shaped connections, e.g. for making Y-shaped pieces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
  • B29K2995/0008—Magnetic or paramagnetic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2023/00—Tubular articles
  • B29L2023/22—Tubes or pipes, i.e. rigid

Definitions

• the present invention relates to temperature self-regulating dual surface heaters and more particularly to a heater having opposed faces which may
• microwave or other oven When the food, such as soup is in a metal can and a microwave oven used, the food must be removed from the metal container and placed in a non- metallic dish for heating. At lunch time lines often form at the microwave as individuals await the opportunity to
• the present invention comprises preferably two generally parallel ferromagnetic plates having Curie temperatures that may or may not be the same but each of which is selected in accordance with the temperature to which their respective loads are to be heated and at least one preferably pancake coil parallel to and located between the plates whereby when the coil is energized by an electric current at high frequency the plates are heated to approximately their Curie temperatures.
• the heater may be employed in butt welding of plastic pipes by energizing the heater until the plates obtain their Curie temperature, then bringing the ends of the pipes to be joined into contact with the plates removing the heater and bringing the ends to be joined into contact with one another under appropriate axial pressure whereby to affect a weld.
• a flat body of thermally conductive material is placed between the heater plate and coil to provide a good thermal path between the coil and plate.
• Heat of the plate is passed to the load and to the extent the temperature of the coil rises above the temperature of the plate, heat energy is passed from the coil to the plate through the thermally conductive material
• the temperature required to produce fusion of the ends of plastic pipe might be 500°F to 600 ⁇ F. Copper, for instance, can withstand such temperatures.
• the heat energy of the coil I 2 R losses
• the coil should be designed to minimize heat energy but to the extent heat is generated it is used by the configuration described to heat the plates. It is found that a flat wound coil generates less heat than an edge wound coil and the temperature of the coil is maintained at an acceptable temperature above the plate temperatures.
• An optimum coil at the present time has been found to be made of a high conductivity copper, for instance, an alloy of 110 copper of rectangular cross section, 0.3 inch wide and 0.062 inch thick.
• the coil is wound as a flat spiral with 7-3/4 turns and a spacing of approximately 0.1 inch between turns.
• the coil is currently used with a heater plate about 1/8 in thickness with 15 mils of Alloy 42-6 on both surfaces of an Aluminum Alloy 1100 plate.
• the plate and coil diameters are about the same, the coil diameter being approximately 8.4 inches with a pitch of about 0.4 inch. Electrically insulating heat conductive potting compound must be used between the coil and the plate otherwise the coil would be short-circuited by the compound.
• the material is maintained quite thin, about 0.15 inch for instance, and must present very good heat transfer properties.
• One such material has a magnesium oxide base and is sold by Coatronics Corporation under the designation Type 906. This material has a thermal conductivity of 40 BTU in/hour"F.
• the dual plate heater may be employed for instance as cooking or warming shelves in a vending machine wherein products to be heated and then dispensed are sandwiched between a plate of each of the shelves above and below the product. Upon a request for a product the plates or more particularly one area of the plates are heated for a predetermined time and then terminating heating and dispensing the product.
• ferromagnetic material in the form of a wire mesh may be employed so that the heater may be made into many different shapes, for instance curved for joining a saddle valve to a pipe.
• the wires may be heated by alternating current flow therethrough or by induction.
• One or two coils may be used.
• the coil or coils may be used with two plates having different Curie temperatures which may be required where that which is to be heated by each plate requires heating to a different temperature.
• Magnetic temperature refers to the temperature at which the plates have lost sufficient ferromagnetism that heating is reduced such that cooling sets in. This phenomena may be detected in several well-known ways and may occur at 1°C to 100°C below absolute Curie temperature depending upon the ferromagnetic material used.
• ferromagnetic material is used herein to include conductive ferromagnetic materials, ferrimagnetic materials, ferrites and other materials that lose a great percentage of their magnetic permeability at a given temperature.
• Figure 1 is a side view in cross section of a basic embodiment of the present invention
• Figure 2 illustrates the magnetic flux coupling from the coil to the heater plates
• FIGS 3a-f illustrate various configurations of heater plates
• Figure 4 is a view in cross section of a prior art heater structure
• Figure 5 is a view in cross section of a dual layer coil embodiment of the invention
• Figure 6 is a view in cross section of a two layer coil wherein the two layers are separated by a layer of insulation;
• Figure 7 is a circuit diagram of a parallel connection of two separate coils, one for each plate;
• Figure 8 is a circuit diagram of two separate coils, one for each plate, connected in series;
• Figure 9 is a cross-sectional view of an embodiment employing two coils connected in parallel
• Figure 10 is a cross-sectional view of two coils connected in parallel with the coils separated by a layer of ferrite material
• Figure 11 is a cross-sectional view of a single two layer coil with the two layers separated by a ferrite material
• Figure 12 is a cross-sectional view of two coils connected in parallel and separated by a layer of insulation
• Figure 13 is a view in elevation of a practical tool embodying the heater of the present invention.
• Figure 14 illustrates the use of the tool of Figure 13 to heat the ends of two plastic pipes to be butt welded
• Figure 15 illustrates an apparatus using dual plate heaters as shelves
• Figure 16 illustrates a heater employing a wire mesh as the heater rather than a rigid plate
• Figure 17 illustrates a modification of the heater of Figure 16
• Figure 18 illustrates a sandwich of a heater coil and heater plates according to the preferred embodiment of the present invention
• Figure 19 illustrates a coil that may be used in the embodiment of Figure 18.
• the heater 2 includes a pancake coil 4 made of Litz wire, conductive tubing or the like located between plates 6 and 8 of refractory material.
• the coil is encapsulated in epoxy type material or foam or other similar insulating material for various purposes such as insulation, spacing of coil from plates and as a material for holding the coil in position.
• Heater plates, specifically plates 10 and 12 of ferromagnetic material are disposed in contact with the refractory materials 6 and 8, respectively, to complete the simplest basic structure. Teflon coatings 17 and 19 to prevent sticking may be applied to the surfaces of the plates 10 and 12 respectively.
• a good heat conductive metal such as copper or aluminum 13 and 15 may be disposed between the plates 10 and 12 and the Teflon coatings. If conductive tubing is employed for the coil material, it may be hollow and may therefore be water or air cooled or the like.
• R.F. power source 14 produces an alternating - discontinuous or continuous electromagnetic field, see Figure 2, that links the plates 10 and 12 producing eddy current and hysteresis losses in the plates to produce heating therein.
• the coupling of energy into the plates 10 and 12 is greatly reduced and the plates dissipate heat more quickly than heat is generated, the plates cool until they again become effectively ferromagnetic and heating is increased to a level above the rate of heat dissipation.
• the plates 10 and 12 may take any desired shape, round, C-shaped, rectangular, cup shaped, L-shaped, etc., a specific shape being tailored to the contemplated use of the heater. See Figures 3a-f.
• Figure 4 of the accompanying drawings there is illustrated a prior art heater wherein the coil 4 is embedded in a ceramic or cast material (such as aluminum) housing 14 to provide rigidity to the structure.
• Calrod heater units are employed.
• a primary advantage to a dual layer coil or of layers of two separate coils connected in series but preferably connected in parallel is in the use of heater plates of different Curie temperatures.
• a single layer coil may be used in such a situation but some interaction between the Curie temperature of the plates is inevitable since when one plate reaches Curie temperature the magnetic flux is coupled primarily into the other plate and temperature control may be affected.
• coil 16 in this configuration is wound as a double layer for the reasons stated above and to provide additional energy to the heater, specifically to provide a greater concentration of flux to the plates.
• an insulator 18 is disposed between the two coils 20 again to provide some decoupling between the coils.
• the insulation 18 of Figure 6 reduces the cross coupling of the magnetic flux of the coils and the structure is more efficient than the structure of Figure 5.
• the proximity of the two coils to one another produces a magnetic field canceling effect that renders the structure of Figure 6 more efficient.
• the coil may be wound as two distinct coils connected either in parallel or series with the parallel construction providing greater energy to the system than the series arrangement as well as providing additional decoupling.
• the parallel arrangement is particularly useful where the two plates have different Curie temperatures. Under such an arrangement if a single coil or two series connected coils, there is some interaction between the coils or effect of one on the other with a single coil resulting in poorer temperature regulation than with parallel connected coils. The single or series coil arrangement in these circumstances is satisfactory; the parallel connected coil arrangement is better.
• FIG. 9 The structure of dual layer coils connected in parallel is illustrated in Figure 9 with a first coil 22 connected between leads 24 and 26 and a second coil 28 connected across leads 30 and 32. Leads 24 and 32 are connected to source lead 34 while leads 26 and 30 are connected to source lead 36.
• a ferrite plate 38 is disposed between coils 22 and 28 to produce a greater concentration of the magnetic flux in heater plates 40 and 42 than is achieved with the use of the plate.
• the flux from a coil is reasonably isolated from the coil on the other side of the ferrite, this arrangement producing the best isolation of coils and plates of any of the embodiments.
• a two layer single coil 40 has the layers separated by a layer of ferrite 42.
• Figure 12 discloses dual coils 44 and 46 connected in parallel and separated by a layer of insulation 48.
• FIG 13 illustrates a practical embodiment of the present invention.
• the device 61 comprises a dual plate heater 50 attached to a housing 52.
• the housing 52 has a long arm 54 terminating in a handle 56.
• the housing may have oppositely disposed angle plates 58 and 60 for support on a structure employed in heating of pipes to be fused.
• the surfaces of the angle plates 58 and 60 may be covered with thermal insulation to reduce transfer of heat to adjacent members.
• Device 61 such as referred to in the description of Figure 13, is illustrated in Figure 14.
• the total structure 62 comprises a pair of parallel rails 64 and 66 spaced apart by the distance between the angle irons 58 and 60 of Figure 13.
• hollow cylindrical tubes may be provided suspended between the rails 64 and 66. These tubes 72 and 74 are illustrated with dashed lines so as not to obscure the other parts of the apparatus. The separation between the tubes is only great enough to permit the dual plate heater to be inserted between them.
• FIG. 15 of the accompanying drawings there is illustrated a depiction of an arrangement wherein a product to be heated is disposed between the shelves ⁇ a container.
• Shelves 80, 82 and 84 are each a dual plate heater.
• a load 86 to be heated is disposed between shelves 80 and 82 and a heat load 88 is dispersed between shelves 82 and 84.
• Each shelf is a dual plate heater which may be of any type illustrated in Figures 1, 4-12 with the bottom of shelf 80 and the top of shelf 82 having preferably the same Curie temperature. Correspondingly the bottom of shelf 82 and top of shelf 84 should preferably have the same Curie temperature.
• the shelves may have a heating zone in one location so that the article to be heated is brought to that zone when it is to be heated prior to dispensing or use.
• the shelves may be ferromagnetic but have a plurality of heat zones defined by individual coils each of which is connected to a source of power as the shelf is rotated to a dispensing position if such is the case.
• a heater employing a mesh of ferromagnetic material embedded in a strong non ⁇ magnetic, heat conductive plastic such as carbon fiber, liquid crystal material or the like.
• a strong non ⁇ magnetic, heat conductive plastic such as carbon fiber, liquid crystal material or the like.
• the advantages to such a structure is two fold; the wire mesh may serve as the heater as well as the ferromagnetic member and the heater is relatively flexible. It can be made in virtually any shape and is readily useable for fusing saddle valves to plastic pipes and other structures of non-planar or irregular shapes.
• FIG 16 The basic concept of such a heater is illustrated in Figure 16 and includes ferromagnetic cross wires 90 and longitudinal ferromagnetic wires 92.
• the wires are interwoven and the mesh may be made up of a continuous wire heated by passing a current via leads 94 and 96 as previously described.
• the wires may be of a conductive material coated with ferromagnetic material to improve Curie temperature control. Two such members are employed, one for each of the two heater surfaces; the second member being comprised of wires 90* and 92'.
• wires 90 and 90' are disposed adjacent surfaces 98 and 100 of a member 102 that also houses coil 104.
• the coil is embedded in a non-heat conductive plastic so as not to hinder the response of the meshes to Curie point control.
• a single heater coil 106 is sandwiched between two heater plates 108 and 110.
• a layer of thermally conductive electrically insulating potting material 112 is disposed between the coil and each of the plates. In a commercial unit the ends of the elements are also covered with the material 112 to provide mechanical strength.
• the coil is in the form of a flat spiral ( Figure 19) of preferably 7-3/4 turns for an 8.4 inch unit.
• the turns as previously indicated are wound from 110 copper strip 0.3x0.062 inch and spaced about 0.10 inch apart.
• the performance of a combination of the coil and one plate is set forth in Table I below.
• the coil and plate are at the same temperature. As current is fed to the coil the plate heats more rapidly as a result of the effect of the magnetic flux on the ferromagnetic plate. After some time period, 5.5 minutes in the present case, the temperature of the plate is autoregulating at between approximately 489° to 490°F while at 4.5 minutes the coil temperature exceeds that of the plate. Since heat dissipation is more rapid from the exposed and loaded plates than from the buried coil. Coil temperature, in this instance, stabilizes at about 535°F well below the temperature the coil wire can withstand. Thus it is seen that by employing a thermally conductive potting compound the coil temperature exceeds the plate temperature, pumps heat to the plate and thence to the load and stabilizes at quite acceptable levels.
• the coil may be fabricated by laser etching or preferably, to reduce cost, by winding a wire of a desired cross section as previously indicated. In this latter approach the wire to be wound and a spacer wire are clamped in a starter tool and the wires are wound about the tool. After winding the spacer wire is removed. It has been found that a spacer wire of a constant width or diameter is not suitable since the outer turns of the spiral tend to open up more than the inner turns.
• a wire of 0.068 inch is used on the innermost turns but is too large for the outer turns.
• a wire 28 inches long and 0.068 inch diameter was used for the inner turns and a 50 inch long wire of 0.053 inch diameter was used beyond the 0.068 inch wire. It may be that the following is preferred: 28 inches of 0.068 inch wire followed by 28 inches of 0.053 inch wire followed by 0.040 inch wire leaving the last two or three turns without a spacer wire.
• the innermost radius of the coil is approximately 0.832 inch.

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• 1992
  • 1992-10-23 EP EP92924135A patent/EP0563374A1/de not_active Withdrawn
  • 1992-10-23 WO PCT/US1992/009154 patent/WO1993008668A1/en not_active Application Discontinuation
  • 1992-10-23 JP JP5507954A patent/JP2662616B2/ja not_active Expired - Lifetime
  • 1992-10-23 CA CA002096725A patent/CA2096725C/en not_active Expired - Lifetime

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