Abstract: A device including, and a method for producing, an electric insulator made of plastic, the insulator having a centrally arranged core made of glass fiber reinforced plastic, and having a plurality of insulation screens arranged coaxially around the core in an offset manner in an axial direction of the core. The method steps include: positioning a casting mold in an axial position around a vertically arranged core; producing a sealing connection between the core and the casting mold; injecting a liquid plastic material under pressure into an axial area of the casting mold; curing the liquid plastic material in the casting mold, thereby creating an insulation screen; deactivating the sealing connection; displacing the casting mold axially in a downward direction along a defined displacement path; and repeating the above steps until an insulator is produced having a desired number of insulation screens.

Abstract: The invention seeks to provide an improved method for producing umbrella-type insulators comprising a core which is configured as a full body or a hollow cavity and umbrellas connected thereto, whereby problem-free de-moulding of said umbrella-type elements is guaranteed despite the fact that a vacuum is formed. This is achieved by fact that the mould (5) is used with at least one valve (8) which is arranged laterally and which extends as far as the surface (4.2) of the umbrella elements or sleeve (4). Immediately after the beginning or during axial movement of the mould (5) away from the umbrella-type element (3) with a sleeve (4), a gas medium is automatically introduced into the cavity (9) which is formed between the core (2) and umbrella-type element (3) with a sleeve (4) and the mould (5) or the valve (S) opens under the effect of traction or pressure and the gaseous medium is thus introduced into the hollow cavity (9).

Abstract: The aim of the invention is to provide an improved ventilation valve (8), especially for ventilating a mold (5) in the production of umbrella type insulators (1), so that harmful deformation of the molded body can be avoided during removal from the mold (5). This is achieved by providing the ventilation valve with a rod-like or pin-shaped housing (8.2) with an orifice (8.5) on one of its front faces and by providing a valve body (8.3) on the other front face which is detachably mounted in an axial extension of the valve housing (8.2).