I. Field of the Invention
The present invention generally relates to the field of devices for holding a workpiece while it is machined. In particular, the present invention is concerned with a rotary table for holding a workpiece which allows the workpiece to be rotated relative to the base of the machine with a minimum amount of friction.
II. Description of the Prior Art
Rotary tables for holding a workpiece while it is being machined are known in the prior art. The prior art devices consist generally of a base mounted to the machine and a rotary member supported by the base. A worm and worm gear device is usually provided which allows the machine operator to rotate a handle attached to the worm which results in a rotation of the rotary member relative to the base. Vertical support of the rotary member is provided by a lubricated flat surface formed on the base which abuts a complementary flat surface on the rotary member. The amount of friction between the base and the rotary member is proportional to the weight supported by the flat surfaces. Heavy workpieces require a substantial amount of torque to rotate the rotary member relative to the base, and considerable effort is required to rotate the worm to achieve rotation of the rotary member relative to the base. This results in wear of the worm and worm gear which results in a considerable amount of backlash and the need for frequent repairs. Chips and debris from the machining operations also tend to migrate and lodge themselves between the flat surfaces further increasing the friction and wear.
III. Information Disclosure Statement
The aforementioned description of the prior art, in the opinion of the applicant and the applicant's attorney, represents the closest prior art and/or information of which the applicant and his attorney are aware.
USPTO Backgrounds
USPTO Backgrounds