Rotary atomizing head type coating machine

1. A rotary atomizing head type coating machine comprising:

an air motor that uses compressed air as a power source;

a hollow rotational shaft that rotates about an axial line (O-O) of the rotational shaft and is rotatably supported by said air motor and an axial tip end of which projects forward from said air motor;

a feed tube that extends to the tip end of said rotational shaft through the inside of said rotational shaft to supply paint;

a rotary atomizing head that is mounted to the tip end of said rotational shaft and includes an outer peripheral surface enlarged in a cup shape, an inner peripheral surface spreading paint supplied from said feed tube and a paint releasing edge positioned in the tip end to release the paint; and

a shaping air ring that surrounds an outer periphery of said rotary atomizing head and an axial tip end of which is arranged in back of said paint releasing edge of said rotary atomizing head,

said shaping air ring including:

a plurality of first shaping air spurting holes that spurt first shaping air toward the periphery of said paint releasing edge; and

a plurality of second shaping air spurting holes that are positioned to be closer to the radial inside than each of said first shaping air spurting holes and are arranged to surround said rotary atomizing head to spurt second shaping air along said outer peripheral surface of said rotary atomizing head,

wherein an inner diameter dimension (d 1 ) of said first shaping air spurting hole at an open end of the first shaping spurting hole is larger than an inner diameter dimension (d 2 ) of said second shaping air spurting hole at an open end of the second shaping spurting hole; and

the number (N 2 ) of said second shaping air spurting holes is set to be smaller than the number (N 1 ) of said first shaping air spurting holes,

wherein an incident angle of (β) of the second shaping air to be spurted from said second shaping air spurting hole to said outer peripheral surface of said rotary atomizing head is set to 12.0 degrees≤β≤13.4 degrees,

wherein the plurality of first shaping air spurting holes are positioned to a radial outside of the paint releasing edge with respect to the axial line of the rotational shaft, the first shaping air spurting holes being positioned at a distance L 1 to the radial outside of the paint releasing edge, where 4.7 mm≤L 1 ≤4.9 mm, and

wherein the plurality of second shaping air spurting holes are positioned to a radial inside of the paint releasing edge with respect to the axial line of the rotational shaft, the second shaping air spurting holes being positioned at a distance L 2 to the radial inside of the paint releasing edge, where 4.0 mm≤L 2 ≤4.5 mm.

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

an inner diameter dimension (d 1 ) of said first shaping air spurting hole is set to 0.8 mm≤d 1 ≤1.2 mm, and

an inner diameter dimension (d 2 ) of said second shaping air spurting hole is set to 0.5 mm≤d 2 ≤0.8 mm.

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

the number (N 2 ) of said second shaping air spurting holes is set to ⅓N 1 ≤N 2 ≤½N 1 to the number (N 1 ) of said first shaping air spurting holes.

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

an inclined angle of (α 1 ) of said first shaping air spurting hole is set to 40 degrees≤α 1 ≤55 degrees relative to the axial line (O-O) of said rotational shaft, and

an inclined angle of (α 2 ) of said second shaping air spurting hole is set to 8 degrees≤α 2 ≤15 degrees relative to the axial line (O-O) of said rotational shaft.