Method and device for producing an electric insulator made from plastic

Method for producing an electric insulator (1) which is made of plastic and has a centrally arranged core or hollow core (2), particularly made of a glass-fiber-reinforced plastic material, as well as a plurality of insulation screens (3) which are arranged coaxially around the core or hollow core (2) and in an offset manner in the axial direction of the core or hollow core (2), characterized by

• a) positioning a casting mold (4) in a defined axial position around the vertically arranged core or hollow core (2), the casting mold (4) having a coaxial opening (5), which is arranged in an axially lower area (6) of the casting mold (4), as well as a mold area (7) open at the top for constructing an insulation screen (3),
• b) producing a sealing connection (8) between the core or hollow core (2) and the casting mold (4) in an axially lower area (9) of the casting mold (4),
• c) injecting a liquid plastic material, particularly a silicone material, at a pressure Pe increased in comparison to the ambient pressure (P0) in an axial area (10) of the casting mold (4), which is situated axially above the sealing connection (8) and axially below the upper end (11) of the casting mold (4), until the casting mold (4) is filled with a defined amount of the plastic material,
• d) letting the plastic material be cured in the casting mold (4),
• e) eliminating the sealing connection (8) between the core or hollow core (2) and the casting mold,
• f) axially displacing the casting mold (4) relative to the core or hollow core (2) downward by a defined displacement path (s),
• g) repeating steps b) to f) until the desired number of insulation screens (3) have been produced.