Rotary atomizing head type coating machine

1. A rotary atomizing head type coating machine comprising:

a cylindrical housing whose inner peripheral side is a motor accommodating portion;

a cylindrical cover covering an outer peripheral side of said housing;

an air motor accommodated in said motor accommodating portion of said housing and rotating and driving a rotational shaft supported by an air bearing by a turbine;

a rotary atomizing head located on the front side of said housing and mounted on a distal end portion of said rotational shaft of said air motor and spraying a paint supplied while rotating together with said rotational shaft;

a feed tube provided by being inserted through said rotational shaft and supplying the paint toward said rotary atomizing head;

a shaping air ring provided by surrounding an outer peripheral surface of said rotary atomizing head on the front end side of said housing and having an air ejection port for ejecting shaping air for shaping a spraying pattern of the paint sprayed from said rotary atomizing head;

a bearing air passage provided on said housing, a distal end of the bearing air passage being connected to the air bearing of the air motor, and supplying bearing air toward said air bearing of said air motor; and

a turbine air passage provided on said housing and supplying driving air toward said turbine of said air motor, wherein:

an annular space surrounding said air motor is provided between said housing and said cover;

said housing includes an bearing air branch passage that branches from said bearing air passage and connects said bearing air passage and said annular space to each other;

by forming said bearing air branch passage to have a narrower diameter as compared with said bearing air passage, a part of bearing air supplied from said bearing air passage toward said air motor is led to said annular space; and

an air discharge passage formed at a position of the outer peripheral surface of said rotary atomizing head, the air discharge passage configured to discharge an outflow air flowing out of said annular space into the atmospheric air at the position of said outer peripheral surface of said rotary atomizing head.

2. The rotary atomizing head type coating machine according to claim 1 , wherein

said bearing air branch passage is formed so that a small amount of air which does not affect an operation of said air bearing by the bearing air is led into said annular space.

3. The rotary atomizing head type coating machine according to claim 1 , wherein

said shaping air ring is configured such that a jig insertion hole into which a rod of a rotation-stopping jig for regulating rotation of said rotational shaft is inserted is provided extending in a radial direction;

an opening on the outer diameter side of said jig insertion hole is opened on a downstream end of said annular space; and

an opening on the inner diameter side of said jig insertion hole is opened in an atomizing head accommodating hole of said shaping air ring surrounding said outer peripheral surface of said rotary atomizing head.

4. The rotary atomizing head type coating machine according to claim 1 , wherein

said housing is composed of a rear housing part supporting the base end side of said feed tube and having an inlet port of each of said air passages and a front housing part provided on the front side of said rear housing part and on which said motor accommodating portion is provided;

said cover is arranged at a position covering the outer peripheral side of said front housing part; and

said annular space is formed between said front housing part and said cover.

5. The rotary atomizing head type coating machine according to claim 1 , wherein

said annular space is provided in a range of an axial length corresponding to said motor accommodating portion of said housing.