Abstract:

A novel type of screw transmission is put forward to solve the problem of high friction coefficient and low efficiency for sliding screw pairs. The nuts are characterized by steel backing and a lining made of carbon fabric reinforced self-lubricant composite material on female thread surfaces. The formulation, preparation, tribological properties and mechanism of lining material are studied. Micro-lubricant-pools are formed on lining surface texture and the synergistic effects of oil and solid lubricants in the pools improved the lubrication greatly. The spiral lining is molded and the lubrication grooves on the surface are also implemented to improve lubrication further. The fabricating processes of the nuts are studied and a nut for a 630kN press is made. The experiments showed that the composite nut exhibited excellent friction properties under heavy-duty condition. Frictional coefficient of the composite nut decreased by 21.2% and transmission efficiency increased by 10.6% in comparison with bronze ZCuSn10Pb1 nut. The development of new type of sliding screw-nuts can not only promote the development of servo presses, but also possess a great significance to all the mechanical equipments with screw-transmission.

Key words: carbon fabric, composite, epoxy resin, self-lubrication, screw transmission