Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B17/00—Insulators or insulating bodies characterised by their form
  • H01B17/38—Fittings, e.g. caps; Fastenings therefor
  • H01B17/40—Cementless fittings
• • 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
  • B29L2031/00—Other particular articles
  • B29L2031/34—Electrical apparatus, e.g. sparking plugs or parts thereof
  • B29L2031/3412—Insulators

Definitions

• the need to attach electrical components such as wires and the like to insulation bodies is usually satisfied by bolting the components into the body.
• the Insulator bodies are usually made of porcelain and any threads in such porcelain bodies are so difficult to produce that they are rarely, if ever, made. If they were produced for some specific reason, a bolt or other fastener inserted into these threads easily strips the threads so that the attached component easily pulls loose from the insulator body.
• To make attachments to porcelain it is conventional to cement a metal cap to the insulator body to attach the electrical components to the metal cap.
• the conventional metal caps have three major disadvantages, namely they present a large area of conductive metal, the cap is the most expensive part of the insulator structure, and the incompatibility of the thermal characteristics between the metal and porcelain give rise to additional problems . Despite these disadvantages, the metal cap has been considered necessary and is in wide-spread commercial use. ,
• the threads in most electrical equipment are a 1 / 2-13 inch thread size.
• a thread of a different size is desirable and the particle size of the acicular aggregate appropriate for forming a 1/2 - 13 thread is not appropriate for forming a different size thread.
• the acicular particles will not line up properly to form a strong thread and instead, a resin rieh weak thread will be produced.
• acicular particles of a smaller size must be used in order to adequately form the finer thread and to maintain the strength and stripping resistance.
• the acicular particles must be of a larger size in order to maintain the strength and stripping resistance. If the acicular particles are not of appropriate size, the resulting body threads will have too much polymer present and will be weak and amenable to stripping.
• Figure 2 is a representation of an insulator ring formed in accordance with the present invention.
• This invention relates to a superior insulating body having threads therein. More particularly, it relates to a superior body of a first insulator material having a first particle size and a receptacle. portion and a second insulator body adapted to be received by the receptacle portion which comprises an acicular aggregate bonded by a cured synthetic resin having at least one thread vibration molded therein, in which the aggregate has a second particle size different from the first particle size and the second particle size is such that at least two individual acicular particles can simultaneously be at least partially contained within the triangular cross-section volume defined between adjacent thread faces.
• the insulator structure of the present invention is a combination of a first insulator body which contains a receptacle portion and a second insulator body which is adapted to be received by the receptacle portion of the first insulator body.
• the first insulator body can be constructed of any suitable insulation material such as a filled synthetic resin, porcelain, and the like.
• the first insulator body can also, but need not necessarily be, constructed of the same material used to construct the second insulator bod.y.
• the first insulator body can be composed of particles of material bonded together in an appropriate way or may be constructed of a material in which discrete particles cannot be identified.
• the material of the first insulator body has a first partic size which will be understood to refer to the size of the particles when such particles can be identified or the size of the entire body in the case that individual particles cannot be identified.
• the receptacle portion of the first insulator body can be in any desired configuration and the receptacle portion in the majority of instances will probably be cylindrical.
• the second insulator body is formed by a polymer concrete 8 resulting from a mixture.
• a curable resin and an acicular aggregate are used.
• the polymer 9 can be any curable resin, preferably electrical insulation grade, which will bind the aggregate particles together and sub ⁇ stantially fill the porosity when it is hardened. Accordingly, epoxy resins, polyester resins, polyurethane resins, polyolefin resins, silicone resins, and the like can be used.
• the polymer 9 is chosen from commercially available products on the basis of its physical aspects, electrical characteristics, hydrophobic characteristics, ability to bind the aggregate and handleability.
• the preferred polymer 9 is an electrical insulation grade epoxy resin.
• the polymer can contain a curing agent which is adapted to be effective in other ambient conditions.
• a suitable hardening agent and catalyst such as an anhydride or amine, which your the epoxy resin at elevated temperature.
• the aggregate particles are subjeeted to compression and shearing stresses when the threads are loaded and this is when maximum strength is attained.
• the majority of the aggregate particles are acicular particles 7 and have a particle size which is different from that of the first insulator body.
• the acicular particles 7 constituent about 65-75% of the aggregate.
• Any electrically insulating material which can be obtained in acicular shape can be used and it has been found that electrical grade porcelain when crushed forms an excellent acicular aggregate with all the desired properties.
• the remainder of the aggregate can be those materials which are normally used as fillers in synthetic organic polymer insulation.
• the conglomeration of materials forming the aggregate should have a variety of particle sizes to reduce the amount of volume which will be filled by the binder portion of the concrete 8.
• at least two different particle sizes of acicular material, adapted to the size of the threads are used.
• At least two of the individually acicular particles should at least partially, and preferably wholly, be simultaneously con ⁇ tained within the triangular cross-section volume de ⁇ fined between adjacent thread faces.
• the binder portion of the polymer concrete 8 should constitute about 5-25 and preferably about 10-20%, of this volume.
• the binder is usually the most expensive material in the polymer concrete 8, it is preferred to keep its concentration in the binder-aggregate admixture as low as practical.
• the aggregate will be about 75-95? of the admixture, preferably about 80-90%. It has been found necessary to mix the binder of the aggregate under a vacuum in order to eliminate large voids and express air in the final product and to insure a complete wetting of the aggregate with the binder resin. A vacuum above 27 inches of mercury, and preferably about 29-30 inches of mercury has been found to be appropriate. For ease of handling, it is preferable to conduct the mi ' xing under an elevated temperature which is below the curing temperature of the binder.
• temperatures of about 50-125 ° C, and preferably about 70-90 C are suitable if an epoxy resin adapted to cure atabout 150 C is utilized.
• the time of mixing is not critical and optimum time intervals can readily be established by a few simple experiments. It is not necessary to vacuum cast the material since it has been found that the existence of a plurality of s all voids do not detract from the insulator Performance of this product although such vacuum casting can be done if the complete absence of voids is necessary.
• the mixing of the aggregate and the binder is completed in a separate apparatus followed by introduction of the admixture into the mold.
• a suitable threaded member can be placed in the mold either before filling with the admixture or can be inserted into the admixture after the mold is filled. It is necessary to vibrate against the threaded member in order to achieve the objects of this invention. Machined in threads do not have the strength of the threads of this invention and would be very. difficult and expensive to produce due to the hardness of the aggregate.
• the amplitude of vibration is not critical and can be varied as desired as long as it is not so violent as to trap air in the admixture. This can be readily ascertained by observation and a just sufficient amplitude should be applied to give mobility to the mass.
• the length of time vibration. continues is a function of the amplitude of the vibration and the temperature conditions.
• the vibration should be continued at least until the extrudation of binder resin on the surface of the admixture can be ob ⁇ served and preferably until the extrudation has sub ⁇ stantially ceased. This observation of extrudation of a vibrating mixture is similar to that encountered when vibrating Portland cement concrete.
• the admixture When vibration is complete, the admixture is cured by raising the temperature to or above the curing temperature of the binder resin. As is known in the art, voiding can be eliminated during your by applying slight pressure to the admixture.
• the admixture can be completely cured in the mold or alternately after the binder has gelled, the admixture can be ejeeted from the mold and cured in an oven thereby freeing the mold for other operations.
• a conduetive paint 5 such as those having a graphite or silver base.
• a conduetive paint distributes the electrical stress around an inserted metal bolt 6 and lubricates the threads making for ease of insertion and removal.
• Figure 2 is a representation of one embodiment of the present invention.
• Four preformed inserts 3 of the polymer concrete described above each having one vibration molded thread 4 therein are set within receptacle portions 2 and held in place by the use of a suitable adhesive.
• the composition used to form the polymer concrete may be 148 parts of XB-2793 hydantoin epoxy resin (made by Ciba-Geigy Corp.), 174 parts of methyl tetrahydrophthatic anhydride, 0.75 part benzoyl dimethylamine, 4 parts of a flow additive (Modaflow from Dow Chemical Co., 50% in the epoxy), 510 parts of 325 mesh crushed quartz, 396 parts of 60 mesh felspatic porcelain and 756 parts of 100 mesh felspatic porcelain. Electrical wires can be connected to the insulator ring 1 by the use of bolts having the same size thread as the thread 4 of preformed insert 3.

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• Insulating Bodies (AREA)
• Insulators (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 1979
  • 1979-07-16 JP JP50113679A patent/JPS55500534A/ja active Pending
  • 1979-07-16 WO PCT/EP1979/000055 patent/WO1980000390A1/de unknown
  • 1979-08-06 BE BE0/196615A patent/BE878092A/xx unknown
  • 1979-08-06 IT IT24949/79A patent/IT1122440B/it active
• 1980
  • 1980-03-11 EP EP79900976A patent/EP0016808A1/en not_active Withdrawn
  • 1980-04-02 DK DK148180A patent/DK148180A/da not_active Application Discontinuation

Non-Patent Citations (1)

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