Externally pressurized gas bearing spindle
AssigneeNtn Corporation
InventorsShoji Fujii, Yoshio Fujikawa
Life of this patent
Estimating the term…
Abstract
A spindle for an electrostatic painting machine has a main spindle and a rotor coupled to the rear end of the main spindle. The main spindle and the rotor are rotatably supported through bearing gaps of externally pressurized gas bearing portions, and a paint spray head is mounted to one end of the main spindle. A current-carrying member having conductivity with the housing is brought into contact with the main spindle and floated off it via a small gap due to dynamic pressure produced by the rotation of the main spindle. With this arrangement, it is ensured that discharge occurs at gaps of externally pressurized gas bearing portions, sputtering is suppressed, and the life of the spindle is prolonged.
Claims26
A spindle arrangement for an electrostatic painting machine, comprising:
- a housing;
- a main spindle mounted in said housing;
- a journal bearing portion for statically supporting said main spindle in a radial direction relative to said housing;
- a thrust bearing portion for statically supporting said main spindle in a thrust direction relative to said housing;
- a paint spray head mounted to one end of said main spindle for atomizing paint;
- and a current-carrying member mounted to said housing with electric conductivity retained and opposite to said main spindle through a gap set to be smaller than gaps of said journal and thrust bearing portions, wherein said current-carrying member is mounted on said housing so as to be movable toward and away from said main spindle, said current-carrying member being brought into contact with said main spindle with a predetermined biasing force when said main spindle is stopped, and said gap being formed by floating said current-carrying member off said main spindle against the biasing force by dynamic pressure produced by rotation of said main spindle;
- and wherein an adjusting means for adjusting said biasing force from outside of said housing is provided.
A spindle arrangement for an electrostatic painting machine, comprising:
- a housing;
- a main spindle mounted in said housing;
- a journal bearing portion for statically supporting said main spindle in a radial direction relative to said housing;
- a thrust bearing portion for statically supporting said main spindle in a thrust direction relative to said housing;
- a paint spray head mounted to one end of said main spindle for atomizing paint;
- and a current-carrying member mounted to said housing with electric conductivity retained and opposite to said main spindle through a gap set to be smaller than gaps of said journal and thrust bearing portions, wherein said current-carrying member is mounted on said housing so as to be movable toward and away from said main spindle, said current-carrying member being brought into contact with said main spindle with a predetermined biasing force when said main spindle is stopped, and said gap being formed by floating said current-carrying member off said main spindle against the biasing force by dynamic pressure produced by rotation of said main spindle;
- and wherein a wedge-shaped space for producing dynamic pressure is formed at a contact surface between said current-carrying member and said main spindle.
A spindle arrangement for an electrostatic painting machine, comprising a main spindle, a bearing sleeve mounted on said main spindle, a housing mounted on said bearing sleeve, and a paint spray head fixedly mounted to one end of said main spindle for atomizing paint, said bearing sleeve and said housing forming a bearing portion for rotatably supporting said main spindle by static pressure, said bearing sleeve being made of a brittle material having self-lubricity, said housing being made of a metallic material having corrosion resistance, wherein said bearing portion comprises a journal bearing portion for statically supporting said main spindle in a radial direction relative to said housing and a thrust bearing portion for statically supporting said main spindle in a thrust direction relative to said housing, and wherein the specific weight of said bearing sleeve is one third or less of that of said housing and the volume of said bearing sleeve is larger than that of said housing.
A spindle arrangement for an electrostatic painting machine, comprising:
- a housing;
- a main spindle mounted in said housing;
- a journal bearing portion for statically supporting said main spindle in a radial direction relative to said housing with a radial bearing gap between said main spindle and said housing;
- a thrust bearing portion for statically supporting said main spindle in a thrust direction relative to said housing with a thrust bearing gap between said main spindle and said housing;
- a paint spray head mounted to one end of said main spindle for atomizing paint;
- a current-carrying member mounted to said housing for conducting electricity from said housing to said main spindle;
- and
- a biasing member arranged to bias said current-carrying member toward a first position in which said current-carrying member contacts said spindle;
- wherein said biasing member and said current-carrying member are arranged such that, upon rotation of said main spindle, a dynamic pressure force is created to push said current-carrying member against a biasing force of said biasing member away from said main spindle to a second position in which a conductive gap is formed between said current-carrying member and said main spindle, said conductive gap being smaller than said radial bearing gap and said thrust bearing gap and allowing electrical conduction from said current-carrying member to said main spindle.
Dependencies are inferred from the claim text.