GB2079069A - Rod type insulator - Google Patents
Rod type insulator Download PDFInfo
- Publication number
- GB2079069A GB2079069A GB8110429A GB8110429A GB2079069A GB 2079069 A GB2079069 A GB 2079069A GB 8110429 A GB8110429 A GB 8110429A GB 8110429 A GB8110429 A GB 8110429A GB 2079069 A GB2079069 A GB 2079069A
- Authority
- GB
- United Kingdom
- Prior art keywords
- rod
- insulator
- covering
- skirts
- mould
- 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.)
- Granted
Links
Classifications
-
- 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
- H01B17/32—Single insulators consisting of two or more dissimilar insulating bodies
Landscapes
- Insulating Bodies (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Insulators (AREA)
Abstract
A rod type insulator (Fig. 1) comprises a glass fibre reinforced plastics rod (1) and a silicone rubber covering (2) with a sleeve portion (3) in close contact with the rod. The covering (2) is formed with skirts in the form of a spiral (4) around the rod. The skirt is twice the diameter of the sleeve and its pitch corresponds to the usual spacing distance for annular skirts. The insulator is made by placing a fibre reinforced rod within a mould having a spiral groove and casting the silicone rubber around the rod. The insulator is used horizontally. A mould for forming the insulator is made by taping a bored block (5) of casting resin with a tap (7), the mould being split longitudinally (Fig. 2 not shown). <IMAGE>
Description
SPECIFICATION
Rod type insulator
This invention relates to a rod type insulator comprising a fibre reinforced plastics rod and a rod covering composed of a sleeve portion in close contact with the rod, and skirts form in one piece with the sleeve portion, and a method of making such a rod type insulator.
The fibre reinforcement may be glass fibre and the covering may be of silicone rubber.
In know rod insulators of this type, the skirts are formed by separate annular discshaped portions of the covering arranged at intervals along the length of the rod.
It is therefore necessary to make annular grooves in the mould used for producing the covering. Owing to the great length of the insulator in proportion to its diameter, these grooves are formed by subdividing the casting mould in the longitudinal direction and cutting the grooves into both parts. Since the cutting of a large number of grooves is relatively costly and the casting mould must be replaced after only a few casts have been made, the cost of manufacturing rod type insulators is substantially increased by the relatively high cost of manufacturing the casting mould.
It is therefore an object of this invention to provide a rod type insulator which can be manufactured less expensively.
According to this invention a rod type insulator comprises a fibre reinforced plastics rod and a covering having skirts which are integral with a sleeve portion of the covering which is in close contact with the rod, the skirts being constituted by at least one spiral surrounding the rod. The invention is applicable primarily to insulators in which the skirts have an outer diameter up to about 40mm.
For rod-type insulators in which skirts have an external diameter of about 40mm or less, this problem is solved according to the invention by making the skirts in the form of one or more than one spiral round the rod.
The formation of one or more than one spiral groove in the internal wall of the casting mould is less expensive than the formation of annular grooves, particularly if the ratio of length to diameter of the insulator is about 5:1 or more. The function of the skirts is not impaired by their spiral formation, at least if the insulator is disposed horizontally or nearly horizontally, because in this position a spiral skirt formation provides drip surfaces for water drops and the like and a dripping edge in the same way as the known skirts. An external skirt diameter of about twice the external diameter of the sleeve-shaped portion of the covering is generally sufficient. Under these conditions, the depth to which the or each spiral groove must be formed in the casting mould raises no technical problems in manufacture.
It is also an object of the present invention to provide a low cost process for the manufacture of the rod type insulator. Starting frm the known process, in which the silicone rubber which is to form the covering is poured into a casting mould which has previously been provided with a smooth longitudinal bore followed by recesses in the surface of the bore to form the skirts, this problem is solved according to the invention by producing the recesses which are to form the skirts by means of a drill designed to produce at least one spiral groove.
So long as the external diameter of the skirts is about 40mm or less, the cost of manufacturing the casting mould is substantially less if such a drill is used to form one or more than one spiral groove than it would be if annular grooves had to be cut into the mould. Moreover, when such a drill is used, no difficulties are encountered in forming the grooves even in a long casting mould, and in particular a mould for a covering in which the ratio of length to diameter is 5:1 or more. In addition, a spiral groove affords the advantage over annular grooves that when the silicone rubber mass is poured into the casting mould, the air can easily escape, so that there is no risk of formation of cavities. This applies particularly if the casting mould is held upright for pouring in the silicone rubber.
An embodiment of the invention will now be described in more detail by way of example, with reference to the drawing, in which:
Figure 1 is an elevation of part of the embodiment; and
Figure 2 is a part section of a casting mould at the beginning of the operation of forming a spiral groove, and showing part of a drill used for forming the groove.
Referring to the drawing, a rod insulator comprises a glass fibre reinforced plastics rod 1 and a silicone rubber covering for the rod, the covering being indicated by reference numeral 2. The covering 2 comprises a sleeve portion 3 in close contact with the surface of the rod 1 and a spiral portion 4 extending over the whole length of the rod and formed in one piece with the sleeve portion 3. The pitch of the spiral portion 4 is such as to correspond substantially to the usual distance between the annular skirts of the known insulators. Further, the spiral portion 4 is of a cross-section substantially similar to that of the known skirts, i.e. its axial thickness diminishes radially outwards from its base where it is attached to the sleeve portion 3, and along the outer edge the two sides of the skirt form a drip edge.
In the present embodiment, the external diameter of the spiral portion 4 is 36mm and the external diameter of the sleeve shaped portion 3 is 1 8mm. The length of the rod insulator is more than five times the external diameter of the spiral portion 4.
The casting mould 5, seen in Fig. 2, which
is required for producing the covering 2, is
made of a casting resin. It is first provided
with a smooth longitudinal bore 6 the diame
ter of which is equal to the external diameter
of the sleeve portion 3. Using a drill 7 in the
form of a screw tap, whose teeth 9 in the
form of a spiral interrupted by fluting 8 have
a shape conforming to that of the skirt, a
spiral groove is worked into the internal wall
of the bore 6.
The glass fibre reinforced plastics rod is
placed in the finished mould 5 with its longi
tudinal axis coinciding with the axis of the
bore 6. The rod 1 is prevented from sagging
by maintaining the mould and rod upright,
with the longitudinal axis vertical. This posi
tion is also maintained subsequently when the
silicone rubber mass is poured into the mould.
Due to the spiral course of the groove which
has been formed by the drill 7, there is no
risk of air inclusions being trapped in the
silicone rubber even in the region of the
groove. As soon as the silicone rubber mass
has solidified, the casting mould 5, which is
split longitudinally, may be removed.
Claims (8)
1. A rod type insulator comprising a fibre
reinforced plastics rod and a covering having
skirts which are integrai with a sleeve portion
of the covering which is in close contact with
the rod, the skirts being constituted by at
least one spiral surrounding the rod.
2. An insulator according to claim 1
wherein the fibre is glass and the covering is
of silicone rubber.
3. An insulator according to claim 1 or
claim 2, wherein the skirt diameter is approxi
mately twice the external diameter of the
sleeve portion.
4. An insulator according to any preceding
claim wherein the external diameter of the
spiral is not more than 40mm.
5. A method of making a rod type insula
tor according to any preceding claim, in which
silicone rubber, to form the covering, is
poured into a mould of casting resin which
has previously been provided with a smooth
longitudinal bore and then with recesses form
ing the skirts on the surface of the bore, the
recesses being formed by a drill producing at
least one spiral groove.
6. A method according to claim 5, wherein the mould is held in the upright
position for introducing the silicone rubber.
7. A rod type insulator constructed and
arranged substantially as herein described and
shown in the drawing.
8. method of making a rod type insula -tor substantially as herein described with reference to the drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3023543A DE3023543C2 (en) | 1980-06-24 | 1980-06-24 | Process for the production of a long rod insulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2079069A true GB2079069A (en) | 1982-01-13 |
| GB2079069B GB2079069B (en) | 1984-04-11 |
Family
ID=6105312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8110429A Expired GB2079069B (en) | 1980-06-24 | 1981-04-02 | Rod type insulator |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE3023543C2 (en) |
| FR (1) | FR2485795A1 (en) |
| GB (1) | GB2079069B (en) |
| ZA (1) | ZA812570B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0821373A1 (en) * | 1996-07-24 | 1998-01-28 | CeramTec AG Innovative Ceramic Engineering | Plastic composite insulator with spiral skirt and its manufacturing method |
| WO2000019257A1 (en) * | 1998-09-29 | 2000-04-06 | Siemens Aktiengesellschaft | Isolator for passing an optical cable held on a phase line of a high tension aerial line |
| US6051190A (en) * | 1997-06-17 | 2000-04-18 | Corning Incorporated | Method and apparatus for transferring and dispensing small volumes of liquid and method for making the apparatus |
| US6844503B2 (en) * | 2001-06-29 | 2005-01-18 | Tyco Electronics U.K. Limited | Helical shed |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3257501A (en) * | 1961-04-20 | 1966-06-21 | Westinghouse Electric Corp | Self-cleaning electrical insulator constructions |
| FR2363170A1 (en) * | 1976-08-26 | 1978-03-24 | Ceraver | Ribbed rubber profile for insulating power line supports - adaptable to various sizes of support by helical winding and pref. made of ethylene!-propylene! rubber |
-
1980
- 1980-06-24 DE DE3023543A patent/DE3023543C2/en not_active Expired
-
1981
- 1981-01-15 FR FR8100638A patent/FR2485795A1/en active Granted
- 1981-04-02 GB GB8110429A patent/GB2079069B/en not_active Expired
- 1981-04-16 ZA ZA00812570A patent/ZA812570B/en unknown
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0821373A1 (en) * | 1996-07-24 | 1998-01-28 | CeramTec AG Innovative Ceramic Engineering | Plastic composite insulator with spiral skirt and its manufacturing method |
| US5925855A (en) * | 1996-07-24 | 1999-07-20 | Ceramtec Ag Innovative Ceramic Engineering | Plastic composite insulator with spiral shield and process for producing it |
| US6051190A (en) * | 1997-06-17 | 2000-04-18 | Corning Incorporated | Method and apparatus for transferring and dispensing small volumes of liquid and method for making the apparatus |
| WO2000019257A1 (en) * | 1998-09-29 | 2000-04-06 | Siemens Aktiengesellschaft | Isolator for passing an optical cable held on a phase line of a high tension aerial line |
| US6507692B1 (en) | 1998-09-29 | 2003-01-14 | Ccs Technology, Inc. | Isolator for passing an optical cable held on a phase line of a high tension aerial line |
| US6844503B2 (en) * | 2001-06-29 | 2005-01-18 | Tyco Electronics U.K. Limited | Helical shed |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2079069B (en) | 1984-04-11 |
| FR2485795B1 (en) | 1984-08-10 |
| FR2485795A1 (en) | 1981-12-31 |
| ZA812570B (en) | 1982-04-28 |
| DE3023543C2 (en) | 1982-09-09 |
| DE3023543A1 (en) | 1982-01-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |