A method of obtaining a polymer insulators

 

(57) Abstract:

The invention relates to methods for high voltage polymer insulators casting method. The technical result - obtaining high performance shells filled siloxane elastomer molding under pressure. The method includes installing rod insulator inside the split mold, the pressure feed metered amounts of insulating material and curing on the rod in two stages, characterized in that the insulating material is subjected to preliminary shear deformation at a certain shear rate and time of deformation, determined from the ratio of the lowest viscosity, MPas; shear rate, with-1; t - time processing, S. table 3.

The invention relates to methods for high voltage polymer insulators casting method.

Polymer insulators have a number of advantages over ceramic: significantly less weight; resistance against vandalism; better resistance to mechanical stress, vibration and shock; the best bit characteristics. The insulators are made of the following polymerchemie (silicone rubbers). Insulators - products manufactured in series (up to 2 to 3 million units per year). The most powerful method of obtaining them is injection molding.

A known method of producing insulators made of epoxy resin molding under pressure (application NDP N 257040, MKI H 01 B, publ. 15.07.86). The products of this material have low resistance to climatic factors, especially in terms of pollution and moisture. This led to the possibility of using epoxy resins only for insulators, low voltage, working in confined spaces (for example, as elements of the closed electric vehicles).

Also known is a method of obtaining insulators by injection molding of a copolymer of ethylene with vinyl acetate, filled with aluminum hydroxide (ed. St. USSR N 1612822, MKI H 01 B 19/00 from 08.08.88). Products made of this material is more resistant to climatic factors than the epoxy resin, however, the low surface hydrophobicity, especially in terms of pollution, leading to the formation of tracks in the local thermal degradation of the material under the action of the partial arcs, limits their use in areas with a high degree of environmental pollution.

A known method of manufacturing a high-voltage insulators made of siloxane (U.S. patent N 4724284, MKI H 01 B 17/02, 17/26, 19/00, publ. 09.02.88), namely, that separately produce a core with devulcanizing shell at its Central part with a certain constant outer diameter, and then make a module out of the elastomer with the outer skirt and the inner cylindrical surface of fixed diameter smaller outer diameter of the shell. The diameter of the inner surface extend to a sufficiently large d the STI put dielectric waterproof seal. Module move the core to a certain axial location in order to form a node of the core and module. Heating this site, vulcanized shell, taking the diameter of the inner surface to the original value. Shrinkage compresses the shell, shifting her material during the vulcanization process longitudinally so that convexity are formed adjacent both axial ends of the module for permanent retention module in the right direction. When this module is almost free from residual stress, and the seal creates a boundary surface between the module and the shell. The shell is solid on the periphery of the outer bump overlying the axial ends of the inner surface and bond with them.

The described method is complex, multi-stage, several time-consuming operations, including manual, but because of low productivity and instability properties of the obtained insulators.

There is also known a method of manufacturing a high-voltage insulators (ed.St. N 1829051 A1, H 01 B 17/02, 19/00 from 1993), namely, that on the rod string pre-moulded from a siloxane elements of the outer shell, and in the docking area served Gerd elements increases the likelihood of moisture and reduces the reliability of the product.

Closest to the proposed is a method of obtaining a ribbed cover" (ed. St. USSR N 1379810, MKI H 01 B 19/00, publ. 24.03.86). In this way the rod insulator have horizontally detachable cover the mold with a perpendicular to the axis of the rod cavity for forming the ribs and with the split plane parallel to the axis of the rod, the cavity serves under the pressure of the metered quantity of insulating material in a plastic condition, utverjdayut it on the rod, then the rod is shifted in the axial direction, and the curing is produced in two stages: to the minimum mechanical strength of the ribs in injection form and final in extra of the mold.

This method does not allow to obtain products of the silicone-filled rubber molding with high performance due to their high viscosity (low yield). At the same time, such systems possess thixotropic properties (see Savvateev, S., Zhukov, I., Bogdanov, C. C. Journal of applied chemistry, 1984, vol VII, No. 12, S. 2749-2755), i.e. their structure is destroyed under the action of shear, the viscosity of the system decreases.

The present invention is to poluchaiutsea of the products is done by pre-shear deformation compositions at a certain shear rate and time of deformation, choose from the relation

< / BR>
where is the least effective viscosity, MPas;

shear rate, with-1;

t - time processing, S.

The method is as follows. Prepared standard composition based on the polysiloxane is subjected to deformation effects in any of the known types of mixers (rotary rubber mixer, roller mixer, screw mixer). When this processing modes (shear rate processing time t) to choose from

< / BR>
The magnitude of the shear rate for any of the types of mixers can be found in reference literature or calculated from simple dependencies (see Vostroknutov E., and other Processing of rubbers and rubber compounds. -M.: Chemistry, 1980, S. 66, 144 - 146).

When doing this according to the viscosity of the composition reaches the lowest value (for this type of equipment and shear rate) and the composition becomes necessary for injection molding fluidity. Further processed in a similar way the composition is metered and serves under pressure to split the heated casting mold with pre-installed in it by the rod, where vulcanescu (curing) after zegarelli this way, using the standard full mix based on siloxane rubbers can provide them with the processing of more high-performance molding under pressure, and to increase reliability by eliminating joints between the separately manufactured by pressing and typed on the terminal shell elements.

Pre-treatment of the mixture has no effect on physical-mechanical and performance properties of the products.

Example 1.

The standard mixture for obtaining of high-voltage insulators (composition: synthetic rubber thermostable with vinyl groups SKTV-1 - 100 wt.h.; filler Aerosil A-175 - 30 wt.h.; antistructuring additive ND-8 - 8 wt.h.; the titanium oxide - 10 wt.h. (or zinc oxide - 5 wt.h.); curing agent - 2,3-dichlorobenzoyl (DHB) - 1.3 wt.h.) was treated in a rotary mixer (speed shear ), recording the processing time and the viscosity of the material. The results are shown in table. 1.

Example 2.

A standard mixture of the same composition was processed in a roller mixer ( 17,79 c-1), recording the processing time and the viscosity of the material. The results are shown in table. 2.

Example 3.

Standard cm mixture according to the number of passes and the viscosity of the material. The results are shown in table. 3.

As can be seen from the presented data, regardless of the type of equipment used, the output of the viscosity at the lowest value (Newtonian flow) occurs when the value .

Using this dependence, it is possible in each case to choose sustainable modes of material processing (speed of rotation of the working parts of the rotary and screw mixers, the frequency of rotation of the rolls and the gap between them to roll mixers, etc).

A method of obtaining a polymer insulators molding, including the installation of a rod within a split mold, the pressure feed metered amounts of insulating material and curing on the rod in two stages, wherein the insulating material on the basis of filled polysiloxane compositions are pre shear deformation at a certain shear rate and time of deformation, we choose the ratio

< / BR>
where is the least effective viscosity of the material, MPa;

shear rate, with1;

t - time processing, S.

 

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Line post insulator // 2248057

FIELD: power engineering; high-voltage line insulators.

SUBSTANCE: proposed line post insulator has two concentrically mounted insulating parts joined together by means of binder. One of parts is made of porcelain. Other insulating part is made of hardened glass. Internal and external insulating parts are also made of hardened glass.

EFFECT: facilitated visual detection of faulty insulator and its replacement.

3 cl, 2 dwg

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