Coating apparatus including a rotating drum have been used for performing film coating, sugar coating, and the like of medical products, food, pesticidal products, and the like, which are prepared as tablets, soft capsules, pellets, grains, and in other similar forms (hereinafter collectively referred to as “particles”).
The following Patent Literatures 1 to 10 disclose this type of coating apparatus.
For example, Patent Literature 1 discloses a coating apparatus including a ventilated-type rotating drum to be driven to rotate about a horizontal axis. The rotating drum includes a peripheral wall portion having a polygonal shape in cross-section, and the peripheral wall portion includes side surfaces having ventilation characteristics due to porous portions. Further, a jacket is mounted on an outer peripheral side of each of the side surfaces of the peripheral wall portion, and a ventilation channel is formed between the jacket and each of the side surfaces of the peripheral wall portion. Further, on another end side of the rotating drum where a rotary drive mechanism including a motor is set, there is arranged a ventilation mechanism for controlling ventilation of a process gas such as dry air for the rotating drum. The ventilation mechanism has a function to communicate the ventilation channels that have come to predetermined positions along with rotation of the rotating drum respectively to an air inlet duct and to an air outlet duct.
Further, Patent Literatures 2 and 3 each disclose a coating apparatus having what is called a jacketless structure. A rotating drum of a coating apparatus illustrated in FIG. 1 of Patent Literature 2 includes the peripheral wall portion having a polygonal shape in cross-section. The peripheral wall portion of the rotating drum includes the side surfaces having ventilation characteristics due to the porous portions. Partition plates are provided respectively at apexes of the polygonal peripheral wall portion, and sliding frames are provided along both axial end portions of the peripheral wall portion. Ventilation spaces are formed by being divided by the side surfaces, the partition plates, and the sliding frames of the peripheral wall portion. The rotating drum is accommodated in an inside of an outer casing, and the outer casing includes an air inlet portion and an air outlet portion provided respectively on an upper side and a lower side thereof. The air outlet portion on the lower side includes a sealing plate made of rubber, a synthetic resin, or the like. Along with the rotation of the rotating drum, the partition plates and the sliding frames of the peripheral wall portion are held in sliding contact with the sealing plate. With this, air in an interior space of the outer casing is prevented from being exhausted without contributing to drying of particles in the rotating drum. The peripheral wall portion includes an upper part opened to the interior space of the outer casing. A drying gas supplied from the air inlet portion on the upper side to the interior space of the outer casing enters the rotating drum through the porous portion at the upper part of the peripheral wall portion, and passes through a particle layer in the rotating drum. Then, along with the rotation of the rotating drum, the drying gas is exhausted to the air outlet portion through the ventilation space that has come to a position corresponding to the air outlet portion on the lower side. A rotating drum of a coating apparatus illustrated in FIG. 2 of Patent Literature 2 includes a peripheral wall portion having a circular shape in cross-section. Further, a sealing plate having a circular-arc shape in cross-section is provided on each of the air inlet portion side and the air outlet portion side. Patent Literature 3 also discloses a coating apparatus having a jacketless structure that is basically the same as that disclosed in Patent Literature 2.