Steel-composite hybrid headstock for high-precision grinding machines

During a typical machining operation in excess of 50% of the compliance (deflection) of the cutting tool comes from the headstock, with the remainder attributable to the bed, slides and structural joints. Therefore, a high dynamic stiffness for the headstocks of machine tool structures is essential to improve their performance. Since the dynamic stiffness is proportional to the static stiffness and damping, a high degree of damping is indispensable for precision grinding machines, especially when machining hard and brittle materials such as glasses and ceramics, i.e. small vibrations may affect the machined surface quality. Since fiber-reinforced composite materials have a high specific modulus, high damping and low thermal expansion it is predicted that the headstock dynamic and thermal characteristics will be improved when such materials are utilized in their manufacture. In this paper the headstock of a precision grinding machine was reinforced using glass fiber epoxy composite material. The static and dynamic characteristics were investigated analytically and experimentally in order to improve the grinding machine performance