CA1225361A - Production of insulated electrical conductors - Google Patents
Production of insulated electrical conductorsInfo
- Publication number
- CA1225361A CA1225361A CA000450800A CA450800A CA1225361A CA 1225361 A CA1225361 A CA 1225361A CA 000450800 A CA000450800 A CA 000450800A CA 450800 A CA450800 A CA 450800A CA 1225361 A CA1225361 A CA 1225361A
- Authority
- CA
- Canada
- Prior art keywords
- conductor
- thickness
- layer
- electromagnets
- particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
- H01B13/28—Applying continuous inductive loading, e.g. Krarup loading
- H01B13/287—Applying continuous inductive loading, e.g. Krarup loading by passing through a coating bath
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/14—Removing excess of molten coatings; Controlling or regulating the coating thickness
- C23C2/24—Removing excess of molten coatings; Controlling or regulating the coating thickness using magnetic or electric fields
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
PRODUCTION OF INSULATED ELECTRICAL CONDUCTORS
Abstract of the Disclosure:
Method and apparatus for forming an insulating layer of substantially constant diameter on an electrical conductor. The layer is coated upon the conductor as a homogeneous mixture of fluid carrier and magnetically permeable particles and the coating operation takes place by passing the conductor upwardly through the fluid mixture and then upwardly and axially through a magnetic field. The field resists the flow of particles through it, thereby permitting a certain thickness of the material to pass through the field and coat the conductor. At least one annular magnet is used to create the field and when two or more magnets are used, these are axially in line with each other.
- i -
Abstract of the Disclosure:
Method and apparatus for forming an insulating layer of substantially constant diameter on an electrical conductor. The layer is coated upon the conductor as a homogeneous mixture of fluid carrier and magnetically permeable particles and the coating operation takes place by passing the conductor upwardly through the fluid mixture and then upwardly and axially through a magnetic field. The field resists the flow of particles through it, thereby permitting a certain thickness of the material to pass through the field and coat the conductor. At least one annular magnet is used to create the field and when two or more magnets are used, these are axially in line with each other.
- i -
Description
I
This invention relates to the production of insulated electrical conductors and is particularly concerned with methods and apparatus for forming insulated telecommunications conductors Telecommunications cable comprises a core of insulated S electrical conductors arranged in twisted pairs Discrete loading is applied at spaced intervals to voice transmission cable to increase the inductance and decrease the attenuation of a pair of conductors over a band of frequencies Loading is provided to decrease attenuation in the voice frequency range, iOeO up to about 5 KHz and is also useful to 10 decrease attenuation in the lower carrier frequency ranges An alternative loading which has been suggested is in the form of a continuous layer surrounding each conductor This layer, which will be referred to in this specification as "continuous loaded layer", is come posed of particles of magnetically permeable material dispersed in a dip 15 electric material, the particles separated from each other to render the layer substantially nonconductive Surrounding this layer is anther layer formed from dielectric material and devoid of magnetically permeable par-tickles This form of insulated conductor has been described in Use Patent ~,079,192, in the name of By Josses dated March 17, 1978 and en-20 titled "Conductor for Reducing Leakage at High Frequencies", and also in British Patent 313,895 and German Offenlegungsschrift 2,050,913 filed October 16, 1970, and entitled "Elektrische Lotting undo Verfahren mu hirer Hairstyling" in the name of Mabel and Metalwork Gutehoffnungshutte Ago Problems are associated with the manufacture of conductor 25 having a continuous loaded layer At least some of these problems relate to the fact that the layer is applied as a mixture of fluid dielectric carrier material and particles. To enable homogeneity of the mix, the carrier material is of essentially lower viscosity than dielectric Jo T
I' ~æ~5~6~
material for conventional insulated layers. More viscous materials result in resistance to dispersion of the particles during mixing. As the composite material has a lower viscosity, it has been found that it cannot be applied by conventional extrusion methods for the forming of dielectric layers upon electrical conductors as the low viscous material flows around its conductor under gravity. Thus in the completed layer after hardening, eccentricity of the layer is found to have occurred. This eccentricity leads to non-uniformity in electrical characteristics of the insulated conductor and uncontrollable variations in mutual capacitance between the conductors in the completed cable.
Further problems occur during the application of the composite material for forming the continuous loaded layer. The magnetically permeable particles tend to be abrasive because they are formed from materials such as ferrite. If a die is used for extruding the composite material onto the conductor, then the abrasive particles passing through the die gradually wear away the material forming the orifice so that the orifice becomes enlarged. Hence, there is a tendency for the continuous loaded layer to become gradually larger in diameter during commercial production. This presents practical problems in that the thickness of the layer will affect the electrical characteristics and performance of the conductor along the length of the cable.
The present invention provides a method and apparatus for forming a layer of the composite material which has a substantially constant diameter along the conductor length, so as to produce a continuous loaded layer which is also of substantially constant diameter.
Accordingly, the present invention provides a method of forming an insulating layer of substantially constant diameter upon an I
electrical conductor, the layer formed from composite material comprising magnetically permeable particles homogeneously mixed with a fluid carrier, the method comprising coating the conductor by passing the conductor upwardly through a quantity of the fluid composite material, and then upwardly and axially through a magnetic field which resists the Flow of the particles there through and hence resists the flow of the mixture to permit a certain thickness only of the material to pass through the field and coat the conductor.
In preferred methods, the conductor passes through at least two annular axially in line DO electromagnets while energizing the electromagnets in continual in-series operations to apply, on each operation, and effective movement of the field in the opposite direction to the movement of the conductor along a pass line, so as to apply a magnetic wiping action to the coating on the conductor to resist the flow of particles against the direction of effective movement of the field. In this case, the operations are sequentially timed in relation to the conductor line speed to ensure a controlled and substantially constant thickness of coating fluid upon the conductor.
The invention also includes an apparatus for forming an insulating layer of substantially constant diameter upon an electrical conductor, the layer formed from a composite material comprising magnetically permeable particles homogeneously mixed with a fluid carrier, the apparatus comprising a container to hold a quantity of the fluid composite material, and an annular magnet disposed directly above the container for passage of the conductor upwardly from the container and axially through the magnet, the magnet having vertically disposed poles to create a magnetic field with lines of force directed downwardly towards the container.
With the use of the above method and apparatus according to the invention, the layer of insulation upon the conductor is applied thereto without the composite material physically contacting any die parts. The die is thus formed by the magnetic field created by the magnet or magnets, as the case may be, and the resistance to movement of the particles through the field dictates the thickness of the layer which is provided upon the conductor. The finished thickness of the fluid layer upon the conductor is dependent not only on the strength of the magnetic field, but also upon the speed of movement of the conductor along its pass line and upon other variables such as the viscosity of the composite fluid material and the permeability of the particles.
Embodiments of the invention will now be described by way of example. With reference to the accompanying drawings in which:
Figure 1 is a cross-sectional view in side elevation through an apparatus according to a first embodiment;
Figure 2 is a side elevation Al view on a smaller scale of the first embodiment forming part of a control means for controlling the thickness of the insulating layer;
Figure 3 is a view similar to Figure 1 of the second embodiment; and Figures and 5 are views, similar to Figure 1, of second and third embodiments.
In a first embodiment as shown in Figure 1, apparatus for forming an insulating layer of substantially constant diameter upon an electrical conductor 10 comprises a container 12 of cylindrical form - ~22~
holding a quantity I of a fluid composite material. This composite material is a homogeneous mixture o-f a fluid carrier and a quantity of magnetically permeable particles. The fluid carrier may be a polymeric or latex material and the permeable particles are conveniently ferrite particles. The composite material is held in a homogeneous state in the manner described in Canadian Patent Application 450,793, Filed March 28, 1984 and entitled "Maintaining homogeneity In A Mixture", in the names of JO Walling, MA. Shannon and G. Arbuthnot. As described in the aforementioned specification lo the container is surrounded by three coils 16, two o-f which are shown in Figure 1. Each of these coils extends around a part of the container with the coil axes in a circumferential inclined manner to the container axis. Hence, the axes of the golfs are inclined to the container axis, i.e. concentrically with the conductor 10, but the lo axes of the coils are also inclined relative to each other. This is shown more clearly by Figure 2, in which -the inclination of the coils and the axes 18, 20 and 22 is apparent.
Homogeneity is insured in the mixture by passing an electric current through the coils 16 in three-phase relationship. The current strength is sufficient to provide a magnetic field with the appropriate flux, e.g. around 10,000 gauss to keep the ferrite particles moving relative to one another in the carrier so as to maintain the homogeneity. because of the relative inclination of the axes 18, 20 and 22, the inclination of the field in the three-phase circuit is constantly changing with regard to the contents of the container. As a result of this and as described in the aforementioned application, components of movement in the ferrite particles are constantly produced and are constantly being changed by the rotating field at its changing angle of inclination. The result of movement of each particle is slightly different from every other particle in its immediate vicinity, and this results in the continuous mixing operation which is required.
According to the present invention, the First embodiment also includes three annular DO electromagnets disposed above the container.
As shown by Figure 1, these magnets 24, 26 and 28 are vertically in axial alignment with each other so as to surround the feed path for conductor issuing From the composite material 14. The three electromagnets are eneryizable in continual in-series operations to apply on each operation an effect movement of a magnetic field in the opposite direction to the movement of the conductor along its pass line, so as to apply a magnetic wiping action to the coating on the conductor as will be described to provide resistance to the flow of -Ferrite particles through the magnets.
Each of these in-series operations en-tails -the energization of electromagnet 24 followed in-series by the energiza-tion of the magnets 26 and 28. As each of the magnets 26 and 28 is energized, then the preceding magnet 24 and 26 is de-energized. Each of the electromagnets is formed in normal manner by windings of copper conductor. Thus, as is required by the present invention, the magnetic field, which is produced by each coil is rendered substantially nonexistent upon the next field being produced. The net effect of each in-series operation, there-Fore, is to provide a magnetic field which moves downwardly towards -the container From one coil to another. Succeeding operations must o-F course be sequentially timed so that the conductor does not move along its path sufficiently far that each section of conductor is not treated in the same way by the magnetic fields. However, with normal line speeds for ; I' I
conductor this problem is no-t encountered as succeeding in-line operations can be timed sufficiently close together to provide -the same treatment for all parts of the conductor. As an example, if the speed of travel of the conductor is 60 ft/min then sequential in-series operations based upon 60 cycles per second or more should present no problems.
A shield (not shown) is provided between the coils 16 and the electromagnets to prevent the electromagnetic fields produced from influencing one another.
In use of the apparatus of the first embodiment, the conductor 10 is fed through a seal in the base of the container 12 and upwardly through the composite material 14, which is maintained in its homogeneous condition by the three-phase operation of the coils 16 as described above. The vertically upwardly moving conductor as it leaves the material 14 is coated by the mixture with a layer 30 of uncontrolled thickness. As the conductor with this coating passes axially through the in-line electromagnets however, the electromagnets are energized by the in-series operations described above, and this has some effect upon the thickness of the coating so as to control that thickness to produce a layer of insulation 32 upon the conductor which is within desired limits.
Each of the electromagnets 24, 26 and 28 has its north and south poles orientated vertically so that when energized, each magnetic Field with flux lines directed downwardly, i.e. in the opposite direction to conduct a movement. This has the effect of resisting passage of the particles through each magnet when i-t is energized and resistance to passage of -the particles, does of course, create an effective resistance of the material in the coating 30 passing -through the magnet. In addition to this, as the magnets are energized in-series in the downward direction, ,. . .
~2æ5~
then the effective downward movement of the magnetic field produces a magnetic wiping action to the coating 30 on the conductor which effectively wipes the coating from the conductor, so as to provide a controlled thickness of the coating at each stage as it passes through the magnets. This is shown in Figure 1 in which it can be seen that the coating 30 gradually reduces in diameter until is is of the required diameter to provide the layer 32. The action of the magnetic field at each of the coils I 26 and 28, therefore, has its own effect upon thinning of the coating material.
The final thickness of the layer 32 depends on various parameters including the viscosity of the material in the container 12, the line speed of the conductor and the permeability of the ferrite particles. A magnetic field strength along the conductor feed path and radially inside the electromagnets of 3,000 gauss or less will control thickness of layer 32. As a result of the wiping action of the magnets, the layer 32 has a thickness which can be controlled within desirable limits thus resulting in a continuous loaded layer of desired thickness after drying.
As can be seen by the above embodiment, the layer 32 is obtained of desired thickness without subjecting a conventional die to the abrasive action of the magnetically permeable particles which Form part of the composite material Hence, no wearing action takes place as the magnetic fields effectively hold the coating 30 sufficiently thinly to space the composite material away From the inside surfaces of the coils.
While the final thickness of the layer 32 is dependent upon material viscosity, conductor line speed and permeability of the ferrite particles, it is also dependent on the magnetic field strength. Thus, it -I 122~
is possible without changing the line speed to control the thickness of the fluid layer 32 before drying in situations where there may be a change in viscosity in the composite material 14 in the container. For instance, as illustrated in Figure 3, a control is used to change the magnetic field strengths dependent upon a measured thickness of the layer 32.
As shown in Figure 3, the container 12 carrying the composite material 14 and the three magnets 24, 26 and 28 are as described in the first embodiment. The coated conductor having its layer 32 of fluid mixture passes upwardly from the magnets towards a drying oven 34.
As the conductor approaches the oven, it passes through a diameter or thickness measuring device 36 which measures the diameter or thickness of the layer 32 upon the conductor. This device may be of known construction and may comprise a laser micrometer or a beta back scattering device continually produces electrical signals corresponding to the diameter of the layer 32 as the conductor passes through the device. These signals are received by a current controller 38 which controls the current passing through each of the magnets 24, 26 and 28. Thus, with one particular strength of signal representing the desired thickness or diameter of the layer 32, any departure from this strength of signal is immediately conveyed to the controller 38 to change the current in the coils correspondingly to adjust the magnetic field strength upon the in-series operations. This field strength is adjusted appropriately so that if the diametral thickness of the layer 32 is a departure from that desired, then the resistance of the magnetic field to flow of the ferrite particles is either increased of decreased accordingly to adjust the amount of the coating 30 to pass through the magnets. Hence, the change in the current in the magnets controls the thickness of the layer 32 within desirable .. ,,, 9 I
limits. In a modification (not shown) of the control described with reference to Figure 2, the measuring device is positioned downstream from the oven 34 to that it actually measures the thickness of the dried layer 32 upon the conductor. Any departure in the thickness or diameter of this layer from that desired in the finished article is immediately corrected by a change in signals sent to the controller 38 which operates in the manner just described to change current in the coils.
In a second embodiment shown by Figure 4, the apparatus in-eluded therein corresponds to that described in the first embodiment except that there are two axially in-line coils 40, 42 instead of three.
With this arrangement, care has to be taken that the sequences of opera-lion are spaced sufficiently apart so that the wiping action does not proceed in an upward direction along the conductor as well as downwardly.
Such a reversal in wiping action could occur if the current passing to the coils merely alternated from one to the other. Thus, the operation of the coils in sequence in each operation should be markedly at a faster rate than the time between succeeding operations. On the other hand the timing between the operations should be sufficiently small that the con-doctor is no-t allowed to travel through -the coils without all parts of the conductor being treated similarly by the wiping action of the magnetic -field. A correct wiping action will of course produce a substantially constant thickness or diameter of the layer 32 upon the conductor.
In a third embodiment shown in Figure 5 and which is otherwise similar to the firs-t and second embodiments, the electromagnets are replaced by a permanent magnet 44.
In use of the third embodinlent, the magnetic field is of course constantly applied to the coating 30 on the conductor as it passes Jo t axially through the magnet. Thus, while a constant thickness of the layer 32 may be obtained, dependent upon the other variables such as viscosity, line speed and permeability, because of the need to stop and start the conductor at the beginning and end of -the operation, it will be found that at the end positions of the conductor the insulation will be of undesirable thickness. It should be borne in mind particularly, therefore, that in use of the third embodiment end sections of the coated conductor should preferably be scrapped.
This invention relates to the production of insulated electrical conductors and is particularly concerned with methods and apparatus for forming insulated telecommunications conductors Telecommunications cable comprises a core of insulated S electrical conductors arranged in twisted pairs Discrete loading is applied at spaced intervals to voice transmission cable to increase the inductance and decrease the attenuation of a pair of conductors over a band of frequencies Loading is provided to decrease attenuation in the voice frequency range, iOeO up to about 5 KHz and is also useful to 10 decrease attenuation in the lower carrier frequency ranges An alternative loading which has been suggested is in the form of a continuous layer surrounding each conductor This layer, which will be referred to in this specification as "continuous loaded layer", is come posed of particles of magnetically permeable material dispersed in a dip 15 electric material, the particles separated from each other to render the layer substantially nonconductive Surrounding this layer is anther layer formed from dielectric material and devoid of magnetically permeable par-tickles This form of insulated conductor has been described in Use Patent ~,079,192, in the name of By Josses dated March 17, 1978 and en-20 titled "Conductor for Reducing Leakage at High Frequencies", and also in British Patent 313,895 and German Offenlegungsschrift 2,050,913 filed October 16, 1970, and entitled "Elektrische Lotting undo Verfahren mu hirer Hairstyling" in the name of Mabel and Metalwork Gutehoffnungshutte Ago Problems are associated with the manufacture of conductor 25 having a continuous loaded layer At least some of these problems relate to the fact that the layer is applied as a mixture of fluid dielectric carrier material and particles. To enable homogeneity of the mix, the carrier material is of essentially lower viscosity than dielectric Jo T
I' ~æ~5~6~
material for conventional insulated layers. More viscous materials result in resistance to dispersion of the particles during mixing. As the composite material has a lower viscosity, it has been found that it cannot be applied by conventional extrusion methods for the forming of dielectric layers upon electrical conductors as the low viscous material flows around its conductor under gravity. Thus in the completed layer after hardening, eccentricity of the layer is found to have occurred. This eccentricity leads to non-uniformity in electrical characteristics of the insulated conductor and uncontrollable variations in mutual capacitance between the conductors in the completed cable.
Further problems occur during the application of the composite material for forming the continuous loaded layer. The magnetically permeable particles tend to be abrasive because they are formed from materials such as ferrite. If a die is used for extruding the composite material onto the conductor, then the abrasive particles passing through the die gradually wear away the material forming the orifice so that the orifice becomes enlarged. Hence, there is a tendency for the continuous loaded layer to become gradually larger in diameter during commercial production. This presents practical problems in that the thickness of the layer will affect the electrical characteristics and performance of the conductor along the length of the cable.
The present invention provides a method and apparatus for forming a layer of the composite material which has a substantially constant diameter along the conductor length, so as to produce a continuous loaded layer which is also of substantially constant diameter.
Accordingly, the present invention provides a method of forming an insulating layer of substantially constant diameter upon an I
electrical conductor, the layer formed from composite material comprising magnetically permeable particles homogeneously mixed with a fluid carrier, the method comprising coating the conductor by passing the conductor upwardly through a quantity of the fluid composite material, and then upwardly and axially through a magnetic field which resists the Flow of the particles there through and hence resists the flow of the mixture to permit a certain thickness only of the material to pass through the field and coat the conductor.
In preferred methods, the conductor passes through at least two annular axially in line DO electromagnets while energizing the electromagnets in continual in-series operations to apply, on each operation, and effective movement of the field in the opposite direction to the movement of the conductor along a pass line, so as to apply a magnetic wiping action to the coating on the conductor to resist the flow of particles against the direction of effective movement of the field. In this case, the operations are sequentially timed in relation to the conductor line speed to ensure a controlled and substantially constant thickness of coating fluid upon the conductor.
The invention also includes an apparatus for forming an insulating layer of substantially constant diameter upon an electrical conductor, the layer formed from a composite material comprising magnetically permeable particles homogeneously mixed with a fluid carrier, the apparatus comprising a container to hold a quantity of the fluid composite material, and an annular magnet disposed directly above the container for passage of the conductor upwardly from the container and axially through the magnet, the magnet having vertically disposed poles to create a magnetic field with lines of force directed downwardly towards the container.
With the use of the above method and apparatus according to the invention, the layer of insulation upon the conductor is applied thereto without the composite material physically contacting any die parts. The die is thus formed by the magnetic field created by the magnet or magnets, as the case may be, and the resistance to movement of the particles through the field dictates the thickness of the layer which is provided upon the conductor. The finished thickness of the fluid layer upon the conductor is dependent not only on the strength of the magnetic field, but also upon the speed of movement of the conductor along its pass line and upon other variables such as the viscosity of the composite fluid material and the permeability of the particles.
Embodiments of the invention will now be described by way of example. With reference to the accompanying drawings in which:
Figure 1 is a cross-sectional view in side elevation through an apparatus according to a first embodiment;
Figure 2 is a side elevation Al view on a smaller scale of the first embodiment forming part of a control means for controlling the thickness of the insulating layer;
Figure 3 is a view similar to Figure 1 of the second embodiment; and Figures and 5 are views, similar to Figure 1, of second and third embodiments.
In a first embodiment as shown in Figure 1, apparatus for forming an insulating layer of substantially constant diameter upon an electrical conductor 10 comprises a container 12 of cylindrical form - ~22~
holding a quantity I of a fluid composite material. This composite material is a homogeneous mixture o-f a fluid carrier and a quantity of magnetically permeable particles. The fluid carrier may be a polymeric or latex material and the permeable particles are conveniently ferrite particles. The composite material is held in a homogeneous state in the manner described in Canadian Patent Application 450,793, Filed March 28, 1984 and entitled "Maintaining homogeneity In A Mixture", in the names of JO Walling, MA. Shannon and G. Arbuthnot. As described in the aforementioned specification lo the container is surrounded by three coils 16, two o-f which are shown in Figure 1. Each of these coils extends around a part of the container with the coil axes in a circumferential inclined manner to the container axis. Hence, the axes of the golfs are inclined to the container axis, i.e. concentrically with the conductor 10, but the lo axes of the coils are also inclined relative to each other. This is shown more clearly by Figure 2, in which -the inclination of the coils and the axes 18, 20 and 22 is apparent.
Homogeneity is insured in the mixture by passing an electric current through the coils 16 in three-phase relationship. The current strength is sufficient to provide a magnetic field with the appropriate flux, e.g. around 10,000 gauss to keep the ferrite particles moving relative to one another in the carrier so as to maintain the homogeneity. because of the relative inclination of the axes 18, 20 and 22, the inclination of the field in the three-phase circuit is constantly changing with regard to the contents of the container. As a result of this and as described in the aforementioned application, components of movement in the ferrite particles are constantly produced and are constantly being changed by the rotating field at its changing angle of inclination. The result of movement of each particle is slightly different from every other particle in its immediate vicinity, and this results in the continuous mixing operation which is required.
According to the present invention, the First embodiment also includes three annular DO electromagnets disposed above the container.
As shown by Figure 1, these magnets 24, 26 and 28 are vertically in axial alignment with each other so as to surround the feed path for conductor issuing From the composite material 14. The three electromagnets are eneryizable in continual in-series operations to apply on each operation an effect movement of a magnetic field in the opposite direction to the movement of the conductor along its pass line, so as to apply a magnetic wiping action to the coating on the conductor as will be described to provide resistance to the flow of -Ferrite particles through the magnets.
Each of these in-series operations en-tails -the energization of electromagnet 24 followed in-series by the energiza-tion of the magnets 26 and 28. As each of the magnets 26 and 28 is energized, then the preceding magnet 24 and 26 is de-energized. Each of the electromagnets is formed in normal manner by windings of copper conductor. Thus, as is required by the present invention, the magnetic field, which is produced by each coil is rendered substantially nonexistent upon the next field being produced. The net effect of each in-series operation, there-Fore, is to provide a magnetic field which moves downwardly towards -the container From one coil to another. Succeeding operations must o-F course be sequentially timed so that the conductor does not move along its path sufficiently far that each section of conductor is not treated in the same way by the magnetic fields. However, with normal line speeds for ; I' I
conductor this problem is no-t encountered as succeeding in-line operations can be timed sufficiently close together to provide -the same treatment for all parts of the conductor. As an example, if the speed of travel of the conductor is 60 ft/min then sequential in-series operations based upon 60 cycles per second or more should present no problems.
A shield (not shown) is provided between the coils 16 and the electromagnets to prevent the electromagnetic fields produced from influencing one another.
In use of the apparatus of the first embodiment, the conductor 10 is fed through a seal in the base of the container 12 and upwardly through the composite material 14, which is maintained in its homogeneous condition by the three-phase operation of the coils 16 as described above. The vertically upwardly moving conductor as it leaves the material 14 is coated by the mixture with a layer 30 of uncontrolled thickness. As the conductor with this coating passes axially through the in-line electromagnets however, the electromagnets are energized by the in-series operations described above, and this has some effect upon the thickness of the coating so as to control that thickness to produce a layer of insulation 32 upon the conductor which is within desired limits.
Each of the electromagnets 24, 26 and 28 has its north and south poles orientated vertically so that when energized, each magnetic Field with flux lines directed downwardly, i.e. in the opposite direction to conduct a movement. This has the effect of resisting passage of the particles through each magnet when i-t is energized and resistance to passage of -the particles, does of course, create an effective resistance of the material in the coating 30 passing -through the magnet. In addition to this, as the magnets are energized in-series in the downward direction, ,. . .
~2æ5~
then the effective downward movement of the magnetic field produces a magnetic wiping action to the coating 30 on the conductor which effectively wipes the coating from the conductor, so as to provide a controlled thickness of the coating at each stage as it passes through the magnets. This is shown in Figure 1 in which it can be seen that the coating 30 gradually reduces in diameter until is is of the required diameter to provide the layer 32. The action of the magnetic field at each of the coils I 26 and 28, therefore, has its own effect upon thinning of the coating material.
The final thickness of the layer 32 depends on various parameters including the viscosity of the material in the container 12, the line speed of the conductor and the permeability of the ferrite particles. A magnetic field strength along the conductor feed path and radially inside the electromagnets of 3,000 gauss or less will control thickness of layer 32. As a result of the wiping action of the magnets, the layer 32 has a thickness which can be controlled within desirable limits thus resulting in a continuous loaded layer of desired thickness after drying.
As can be seen by the above embodiment, the layer 32 is obtained of desired thickness without subjecting a conventional die to the abrasive action of the magnetically permeable particles which Form part of the composite material Hence, no wearing action takes place as the magnetic fields effectively hold the coating 30 sufficiently thinly to space the composite material away From the inside surfaces of the coils.
While the final thickness of the layer 32 is dependent upon material viscosity, conductor line speed and permeability of the ferrite particles, it is also dependent on the magnetic field strength. Thus, it -I 122~
is possible without changing the line speed to control the thickness of the fluid layer 32 before drying in situations where there may be a change in viscosity in the composite material 14 in the container. For instance, as illustrated in Figure 3, a control is used to change the magnetic field strengths dependent upon a measured thickness of the layer 32.
As shown in Figure 3, the container 12 carrying the composite material 14 and the three magnets 24, 26 and 28 are as described in the first embodiment. The coated conductor having its layer 32 of fluid mixture passes upwardly from the magnets towards a drying oven 34.
As the conductor approaches the oven, it passes through a diameter or thickness measuring device 36 which measures the diameter or thickness of the layer 32 upon the conductor. This device may be of known construction and may comprise a laser micrometer or a beta back scattering device continually produces electrical signals corresponding to the diameter of the layer 32 as the conductor passes through the device. These signals are received by a current controller 38 which controls the current passing through each of the magnets 24, 26 and 28. Thus, with one particular strength of signal representing the desired thickness or diameter of the layer 32, any departure from this strength of signal is immediately conveyed to the controller 38 to change the current in the coils correspondingly to adjust the magnetic field strength upon the in-series operations. This field strength is adjusted appropriately so that if the diametral thickness of the layer 32 is a departure from that desired, then the resistance of the magnetic field to flow of the ferrite particles is either increased of decreased accordingly to adjust the amount of the coating 30 to pass through the magnets. Hence, the change in the current in the magnets controls the thickness of the layer 32 within desirable .. ,,, 9 I
limits. In a modification (not shown) of the control described with reference to Figure 2, the measuring device is positioned downstream from the oven 34 to that it actually measures the thickness of the dried layer 32 upon the conductor. Any departure in the thickness or diameter of this layer from that desired in the finished article is immediately corrected by a change in signals sent to the controller 38 which operates in the manner just described to change current in the coils.
In a second embodiment shown by Figure 4, the apparatus in-eluded therein corresponds to that described in the first embodiment except that there are two axially in-line coils 40, 42 instead of three.
With this arrangement, care has to be taken that the sequences of opera-lion are spaced sufficiently apart so that the wiping action does not proceed in an upward direction along the conductor as well as downwardly.
Such a reversal in wiping action could occur if the current passing to the coils merely alternated from one to the other. Thus, the operation of the coils in sequence in each operation should be markedly at a faster rate than the time between succeeding operations. On the other hand the timing between the operations should be sufficiently small that the con-doctor is no-t allowed to travel through -the coils without all parts of the conductor being treated similarly by the wiping action of the magnetic -field. A correct wiping action will of course produce a substantially constant thickness or diameter of the layer 32 upon the conductor.
In a third embodiment shown in Figure 5 and which is otherwise similar to the firs-t and second embodiments, the electromagnets are replaced by a permanent magnet 44.
In use of the third embodinlent, the magnetic field is of course constantly applied to the coating 30 on the conductor as it passes Jo t axially through the magnet. Thus, while a constant thickness of the layer 32 may be obtained, dependent upon the other variables such as viscosity, line speed and permeability, because of the need to stop and start the conductor at the beginning and end of -the operation, it will be found that at the end positions of the conductor the insulation will be of undesirable thickness. It should be borne in mind particularly, therefore, that in use of the third embodiment end sections of the coated conductor should preferably be scrapped.
Claims (10)
1. A method of forming an insulating layer of substantially constant diameter upon an electrical conductor, the layer formed from composite material comprising magnetically permeable particles, the method comprising coating the conductor by passing the conductor upwardly through a quantity of the composite material in a fluid state, and then upwardly and axially through a magnetic field which resists the flow of the particles therethrough and hence resists the flow of the mixture in order to permit a certain thickness only of the material to pass through the field and coat the conductor.
2. A method according to claim 1, comprising passing the coated conductor through a magnetic field created by an annular permanent magnet.
3. A method according to claim 1, comprising passing the coated conductor through at least two annular axially in-line D.C.
electromagnets while energizing the electromagnets in continual in-series operations to apply in each operation, an effective movement of the field in the opposite direction to the movement of the conductor along the pass line and apply a magnetic wiping action to the coating on the conductor to provide a resistance to the flow of the particles against the direction of effective movement of the field, the operations sequentially timed in relation to the line speed of the conductor to ensure a controlled and substantially constant thickness of coating fluid upon the conductor.
electromagnets while energizing the electromagnets in continual in-series operations to apply in each operation, an effective movement of the field in the opposite direction to the movement of the conductor along the pass line and apply a magnetic wiping action to the coating on the conductor to provide a resistance to the flow of the particles against the direction of effective movement of the field, the operations sequentially timed in relation to the line speed of the conductor to ensure a controlled and substantially constant thickness of coating fluid upon the conductor.
4. A method according to claim 3, wherein there are at least three annular in-line electromagnets through which the coated conductor is being passed.
5. A method according to claim 3, comprising passing an ad-justable current through each of the electromagnets, measuring the thick-ness or diameter of the layer of material on the conductor after the conductor has passed through the magnetic field, producing an electric signal corresponding to the measured diameter or thickness of the layer upon the conductor and using the signal to control the strength of the current applied to the electromagnets so as to vary the magnetic field to change the resistance of flow to the particles through the field corres-pondingly to adjust the thickness of the layer towards that desired.
6. Apparatus for forming an insulating layer of substantially constant diameter upon an electrical conductor, the layer being formed from composite material comprising magnetically permeable particles homogeneously mixed with a fluid carrier, the apparatus comprising a container to hold a quantity of the composite material in fluid state, an annular magnet disposed directly above the container, for passage of the conductor upwardly from the container and means for conveying the conductor axially through the magnet, the magnet having vertically dis-posed poles to create a magnetic field with lines of force directed downwardly.
7. Apparatus according to claim 6, comprising at least two annular axially in-line electromagnets disposed above the container, the electromagnets energizable in continual in-series operations to apply, on each operation, an effective movement of the field in the opposite direction to the movement of the conductor along the pass line and apply a magnetic wiping action to the coating on the conductor to resist the flow of the particles against the direction of effective movement of the field with the operations sequentially timed in relation to the conductor line speed to ensure a controlled and substantially constant thickness of coating fluid upon the conductor.
8. Apparatus according to claim 7, comprising at least 3 axially in-line electromagnets disposed above the container.
9. Apparatus according to claim 6, provided with a diameter or thickness measuring means to provide a signal corresponding to the diameter or thickness of the layer of material upon the conductor after passage through the magnets, and a current controller to control the current supplied to the magnets and thus to control the strength of the magnetic field, the current controller responsive to the strength of the signals received from the measuring means to change the current and the magnetic field strength dependent upon the measured diameter or thickness so as to change resistance to flow of the particles and thus change the thickness of the composite material applied to the conductor, thereby to maintain the thickness of the material between certain limits.
10. Apparatus according to claim 6, wherein the magnet is a permanent magnet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000450800A CA1225361A (en) | 1984-03-28 | 1984-03-28 | Production of insulated electrical conductors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000450800A CA1225361A (en) | 1984-03-28 | 1984-03-28 | Production of insulated electrical conductors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1225361A true CA1225361A (en) | 1987-08-11 |
Family
ID=4127543
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000450800A Expired CA1225361A (en) | 1984-03-28 | 1984-03-28 | Production of insulated electrical conductors |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1225361A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5333646A (en) * | 1989-06-02 | 1994-08-02 | Delot Process, S.A. | Electromagnetic valve for controlling the flow of a fluid in a pipe |
| US5338581A (en) * | 1989-06-09 | 1994-08-16 | Delot Process, S.A. | Process and apparatus for the continuous or intermittent coating of objects in a liquid mass |
-
1984
- 1984-03-28 CA CA000450800A patent/CA1225361A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5333646A (en) * | 1989-06-02 | 1994-08-02 | Delot Process, S.A. | Electromagnetic valve for controlling the flow of a fluid in a pipe |
| US5338581A (en) * | 1989-06-09 | 1994-08-16 | Delot Process, S.A. | Process and apparatus for the continuous or intermittent coating of objects in a liquid mass |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1243063B1 (en) | Method for producing a high-quality insulation of electric conductors or conductor bundles of rotating electrical machines using spray sintering | |
| CA1225361A (en) | Production of insulated electrical conductors | |
| US1672979A (en) | Loaded conductor | |
| DE19963376A1 (en) | Process for the production of a high-quality insulation of electrical conductors or conductor bundles of rotating electrical machines by means of vortex sintering | |
| DE2850783C2 (en) | Method for controlling the coating thickness of metal substrates coated with liquid metal and apparatus for carrying out this method | |
| US4565591A (en) | Method and apparatus for making a magnetically loaded insulated electrical conductor | |
| EP0157496A2 (en) | Monitoring of magnetically permeable particles in a carrier material | |
| CA1225358A (en) | Applying magnetic field to fluid mixture including magnetic particles through a coil | |
| US4518633A (en) | Production of insulated electrical conductors | |
| DE3065570D1 (en) | Method and device for manufacturing varnish-insulated winding wire, in particular thick wires | |
| US4587133A (en) | Production of insulated electrical conductors | |
| US4514435A (en) | Method for production of dielectric insulation layers upon electrical conductors | |
| CA3046756A1 (en) | Multi-material fabrication with direct-write additive manufacturing | |
| US4515826A (en) | Method of production of dielectric insulation layers upon electrical conductors | |
| EP3784414A1 (en) | Device, method and computer program for coating at least one fibre | |
| CA1239373A (en) | Production of dielectric insulation layers upon electrical conductors | |
| CA1225359A (en) | Production of dielectric insulation layers upon electrical conductors | |
| CA1225360A (en) | Passing conductor with layer including magnetically permeable particles through magnetic field | |
| CN107578883A (en) | Conical broadband inductor and processing method thereof | |
| NO791467L (en) | ELECTRICAL CONDUCTOR WITH CONTINUOUS INDUCTIVE LOAD AND PROCEDURE FOR MANUFACTURE OF SUCH A CONDUCTOR | |
| CA1209948A (en) | Production of dielectric insulation layers upon electrical conductors | |
| JP4167555B2 (en) | Insulated coated electric wire and method and apparatus for manufacturing the same | |
| DE2505080C3 (en) | Radio interference suppression choke and method for its manufacture | |
| Sumiyoshi et al. | Coupling-current loss in a multifilamentary superconducting wire with a normal-metal core | |
| US4857676A (en) | Magnetically permeable particles in telecommunications cable |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |