Contact brush for electrical machines - made by rolling expanded graphite flakes into foils, which are then stacked and pressed to form laminated brush

摘要

The brush is made starting from graphite particles which are converted into expanded flakes. The flakes are rolled to obtain graphite foils, which are stacked to form a laminate which is pressed. In the pressing, the surfaces of the foils are aligned at 90 deg. w.r.t. the contact surface of the pressing. The graphite foils are pref. also bonded together by small synthetic resin- or coke-bridges. Prior to rolling, the expanded graphite flakes are pref. mixed with silica flour or coke flour, and/or film forming substances such as MoS2 or CdS. The brush possesses good dynamic contact properties, and has high transverse electrical resistance.