B29C 65/3464

Joining {or sealing} of preformed parts {, e.g. welding of plastics materials}; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" {characterised by the type of heated elements which remain in the joint characterised by the cross-section of said heated elements which remain in the joint or by the cross-section of their coating, e.g. being triangular}