Powder coating apparatus

A powder coating apparatus, comprising:

• a transporter that transports an object to be coated;
• an applying unit disposed to be opposed to a surface to be coated of the transported object to be coated and applying a charged thermosetting powder coating material onto the surface to be coated of the object to be coated, wherein the applying unit includes an applying section including a cylindrical or columnar applying member that is disposed to be separated from the surface to be coated of the object to be coated, is rotated in a direction identical to or opposite from a transport direction of the object to be coated, and transfers and applies the powder coating material attached to the surface of the applying member onto the surface to be coated of the object to be coated according to a potential difference between the applying member and the surface to be coated of the object to be coated, and a supplying section including a cylindrical or columnar supplying member that supplies the powder coating material onto the surface of the applying member;
• a voltage applying device that includes a voltage applying unit applying a voltage in which an alternating voltage is superimposed with a direct voltage applying a potential difference between the applying member and the surface to be coated of the object to be coated;
• a heater that heats and thermally cures a powder particle layer of the powder coating material applied onto the surface to be coated of the object to be coated;
• a height measurer for a surface to be coated that measures a height of the surface to be coated of the object to be coated from a transport surface on an upstream side of the applying unit in the transport direction of the object to be coated;
• a discharge voltage measurer that includes a discharge electrode disposed to be separated from the surface to be coated of the object to be coated on the upstream side of the applying unit in the transport direction of the object to be coated, applies a signal voltage to the discharge electrode, and measures a voltage discharged between the discharge electrode and the surface to be coated of the object to be coated;
• and
• a controller configured to control the voltage applying unit such that an amplitude of the alternating voltage of the voltage applying unit is determined and the direct voltage superimposed with the alternating voltage is applied in accordance with the measured height and discharged voltage.