| 摘要 |
1530994 Heat recoverable insulators RAYCHEM Ltd 7 Oct 1975 [8 Oct 1974] 43536/74 Heading H2C [Also in Division B5] A heat recoverable article, e.g. an insulator, for use in covering a substrate, comprises an elongate hollow member having at least one hollow end and a plurality of outwardly extending sheds 3 each of which extends round at least part of the periphery of the article. The article is formed of a heat-recoverable material such that, both before recovery and on partial recovery of the article around and into contact with the substrate, each shed will be inclined to the longitudinal axis of the article whilst on complete recovery of the article, the sheds are substantially perpendicular to said axis. As described, the sheds may each extend continuously around the periphery. Alternatively each may extend over a part of the periphery in which case the article may be of the wrap around form, i.e. a longitudinal seam is formed after moulding. The outwardly extending portions are preferably integrally formed with the remainder, and one or more may extend helically around the article. In a modification all the portions may be provided by a single helical member. As described, each article is preferably moulded in a heat-stable state with the outwardly extending portions substantially perpendicular to the longitudinal axis thereby allowing ready removal from the mould. The internal dimensions of the article are then expanded, e.g. by a mandrel, to a first heatrecoverable state, and slipped over the substrate, e.g. bush or insulating post. The article is then heated so as to partially recover around the substrate. The composite structure, i.e. article plus substrate, may be used as a high voltage insulator, the outer surface then being of a non- tracking material. The substrate may be a fibre reinforced electrically insulating material. The article alone may provide insulation in which case the substrate may be an electrical component, e.g. a cable. An adhesive may be used to bond the article to the substrate and at least part of the article surface in contact with the substrate may be provided with a stress-grading layer. An extensive list of possible adhesives is given. Dimensions are given. |
