Patent Description:
Generally, a coating device coating coated objects such as automobile bodies includes: an arm portion with a base end side mounted to an operating device of an coating robot and the like; a head portion provided at the tip side of the arm portion; an air motor provided at the head portion and powered by compressed air; a hollow rotating shaft rotatably supported by the air motor and the tip of the hollow rotating shaft protrudes forward from the air motor; a feed tube extending through the inside of the rotating shaft to the tip of the rotating shaft for supplying paint; a rotary atomizing head mounted at the tip of the rotating shaft and spraying the paint supplied from the feed tube to the coated object; a valve device provided at the head portion and provided with a switching valve including a trigger valve for opening and closing the paint supply path to the feed tube by pilot air; and a cover portion formed as a resin cylindrical body covering the outer peripheral side of the head portion.

In addition, as a coating device for improving the coating efficiency of paint, electrostatic coating devices are known. The electrostatic coating device is provided with a high voltage generator at the arm portion, which applies a high voltage to the paint supplied to a rotary atomizing head through an air motor and a rotating shaft (Patent Literature <NUM>).

Patent Literature <NUM> : International Publication No.<CIT>.

The electrostatic coating device of Patent Literature <NUM> causes a high voltage generated by a high voltage generator to electrically charge an air motor, a rotating shaft, and the like, applying the high voltage to paint supplied to a rotary atomizing head through a feed tube. Thereby, the electrostatic coating device causes the electrically charged paint particles sprayed from the rotary atomizing head to fly toward the grounded coated object.

In this case, ozone is released from the metal air motor and the rotating shaft which are electrically charged with high voltage. Ozone released from these components is exhausted together with compressed air (exhaust) which serves as the driving source of the air motor and shaping air which adjusts the spray pattern of the paint.

However, the electrostatic coating device has other metal components such as a valve device, and the ozone released from the valve device and the like will stay in the gap between the head portion and the cover portion and the gap between the arm portion and the head portion. In this way, the stayed ozone may gradually diffuse to other gaps and corrode resin components. Corroded components have to be replaced as they may also cause high voltage leaks, which reduces the durability of components.

Other electrostatic coating devices are disclosed in documents <CIT>, Us <CIT>and <CIT>.

Given the above-mentioned problems of prior art, the present disclosure has been made to provide an electrostatic coating device capable of improving the durability of resin components by preventing ozone from staying in gaps where there is no air flow.

The present disclosure is an electrostatic coating device including: an arm portion with a base end side mounted to an operating device; a head portion provided at the tip side of the arm portion; an air motor provided at the head portion and powered by compressed air, a hollow rotating shaft rotatably supported by the air motor and the tip of the hollow rotating shaft protrudes forward from the air motor; a feed tube extending through the inside of the rotating shaft to the tip of the rotating shaft for supplying paint; a rotary atomizing head mounted at the tip of the rotating shaft and spraying the paint supplied from the feed tube to the coated object; a valve device provided at the head portion and provided with a switching valve including a trigger valve for opening and closing the paint supply path to the feed tube by pilot air; a high voltage generator provided at the arm portion, which applies a high voltage to the paint supplied to the rotary atomizing head through the valve device, the air motor and the rotating shaft; and a cover portion formed as a resin cylindrical body covering the outer peripheral side of the head portion, and in the electrostatic coating device, a cylindrical gap is provided between the head portion and the cover portion, the cylindrical gap surrounding an outer peripheral side of the head portion, the head portion is provided with a pilot air introduction path guiding the pilot air exhausted from the switching valve to the cylindrical gap; the arm portion is provided with a pilot air exhaust path exhausting the pilot air from the cylindrical gap to the outside.

According to the present disclosure, ozone can be prevented from staying in the gap where there is no air flow and the durability of resin components can be improved.

Hereinafter, an electrostatic coating device according to an embodiment of the present disclosure will be described in detail below with reference to <FIG>.

In <FIG>, the coating robot <NUM> as a representative example of the operating device includes a base <NUM>, a vertical arm <NUM> operably provided on the base <NUM> and a horizontal arm <NUM> as an arm portion rotatably provided at the tip of the vertical arm <NUM>. The tip portion of the horizontal arm <NUM> is a rotatable wrist portion 104A. The arm portion <NUM> of the electrostatic coating device <NUM> described later is mounted to the wrist portion 104A.

Next, the configuration of the electrostatic coating device <NUM> according to the embodiment of the present disclosure will be described. The electrostatic coating device <NUM> is mounted to the wrist portion 104A of the horizontal arm <NUM> of the coating robot <NUM>. As shown in <FIG>, the electrostatic coating device <NUM> includes an arm portion <NUM>, a head portion <NUM>, an air motor <NUM>, a rotating shaft <NUM>, a feed tube <NUM>, a rotary atomizing head <NUM>, a valve device <NUM>, a high voltage generator <NUM>, a cover portion <NUM>, a pilot air introduction path <NUM> and a pilot air exhaust path <NUM> described later.

In the arm portion <NUM>, the base end portion 2A in the longitudinal direction as the base end side is mounted to the tip portion of the wrist portion 104A of the horizontal arm <NUM>. The arm portion <NUM> is formed as a cylindrical body made of resin. In addition, the tip side of the arm portion <NUM> is bent obliquely. The tip portion 2B of the arm portion <NUM> has a tip surface 2C including a circular flat surface. The tip surface 2C faces the base end surface 3C of the head portion <NUM> described later and the base end surface 12A of the base member <NUM> constituting the valve device <NUM>. Further, on the tip side of the arm portion <NUM>, a shorty circular cylinder portion 2D is provided on the periphery of the tip surface 2C. A sealing member <NUM> described later is adhered to the inner peripheral surface of the cylinder portion 2D.

Provided in the arm portion <NUM> is a high voltage generator <NUM> described later extending in the axial direction. In addition, inside the arm portion <NUM>, a pilot air exhaust path <NUM>, a first dual pipeline <NUM>, a second dual pipeline <NUM> and the like described later are provided at positions surrounding the high voltage generator <NUM>.

The head portion <NUM> is provided on the tip side of the arm portion <NUM>. The head portion <NUM> is formed as a resin cylindrical body with the base end portion 3A mounted to the tip portion 2B of the arm portion <NUM>. A valve device <NUM> described later is provided on the base end portion 3A side of the head portion <NUM>. In addition, an air motor <NUM>, a shaping air ring <NUM> and the like described later are provided on the tip portion 3B side within the head portion <NUM>.

The base end face 3C of the head portion <NUM> faces the tip surface 2C of the arm portion <NUM> with a planar gap <NUM> described later sandwiched therebetween. On the base end side of the head portion <NUM>, a valve mounting hole 3D is provided on the outer peripheral side of the valve device <NUM>. As shown in <FIG>, the valve mounting hole 3D passes through the head portion <NUM> in the radial direction. Further, a plurality of valve mounting holes 3D are provided at intervals in the circumferential direction, for example, four valve mounting holes 3D are provided corresponding to the switching valves <NUM> to <NUM> of the valve device <NUM>.

Here, the planar gap <NUM> is provided between the tip portion 2B of the arm portion <NUM> and the base end portion 3A of the head portion <NUM>. Specifically, a majority of the planar gap <NUM> is disposed between the tip surface 2C of the arm portion <NUM> and the base end surface 3C of the head portion <NUM>, and between the tip surface 2C and the base end surface 12A of the base member <NUM>. In addition, as shown in <FIG>, the planar gap <NUM> is formed in a circular shape. On this basis, a part of the outer peripheral side of the planar gap <NUM> extends along the cylinder portion 2D of the arm portion <NUM> to the tip side. Further, the planar gap <NUM> is actually a small gap, e.g., <NUM> or less, although it is illustrated as a large gap, and there may be a portion where the arm portion <NUM> and the head portion <NUM> contacts each other partially.

The sealing member <NUM> is provided on the outer peripheral side of the base end portion 3A of the head portion <NUM>. The sealing member <NUM> includes a resin O-ring or the like and seals the planar gap <NUM> by adhering to the inner peripheral surface of the cylinder portion 2D of the arm portion <NUM>. Thereby, the tip portion 2B of the arm portion <NUM> and the base end portion 3A of the head portion <NUM> are mounted facing each other with the sealing member <NUM> sandwiched therebetween in the periphery.

The air motor <NUM> is arranged coaxially with the head portion <NUM> within the head portion <NUM>. The air motor <NUM> uses compressed air as the power source to rotate the rotating shaft <NUM> and the rotary atomizing head <NUM> at a high speed of, for example, <NUM>,000rpm to <NUM>,000rpm. The air motor <NUM> includes a stepped cylindrical motor cases 6A mounted in the head portion <NUM>, a turbine 6B rotatably accommodated on the base end side of the motor case 6A, and an air bearing 6C provided on the inner peripheral side of the motor case 6A and rotatably supporting the rotation shaft <NUM>.

Here, compressed air for driving is supplied to the turbine 6B via a compressed air supply path (not shown). In addition, the compressed air flowing out of the turbine 6B is exhausted to the outside via the compressed air exhaust path <NUM> of the first dual pipeline <NUM> and the compressed air exhaust path <NUM> of the second dual pipeline <NUM> described later.

The rotating shaft <NUM> is formed as a cylindrical body which is rotatably supported on the air motor <NUM> by the air bearing 6C. The rotating shaft <NUM> is arranged to extend axially to the center of the motor case 6A. The base end side of the rotating shaft <NUM> is integrally mounted at the center of the turbine 6B. On the other hand, the tip of the rotating shaft <NUM> protrudes from the motor case 6A to the front side (tip side). The rotary atomizing head <NUM> is mounted to the tip portion of the rotating shaft <NUM>.

The feed tube <NUM> extends through the inside of the rotating shaft <NUM> to the tip of the rotating shaft <NUM>. The tip side of the feed tube <NUM> protrudes from the tip of the rotating shaft <NUM> and extends into the rotary atomizing head <NUM>. The base end side of the feed tube <NUM> is mounted at the center position of the base member <NUM> of the valve device <NUM>. In the feed tube <NUM>, an internal paint passage (not shown) is connected to a paint supply source (not shown) including a color change valve device via a paint supply path 12B described later. Further, the base end side of the feed tube <NUM> may be mounted to the head by extending the head portion to a position facing the base end side of the motor case 6A.

When performing the coating operation, the feed tube <NUM> supplies the paint from the paint passage toward the rotary atomizing head <NUM>. On the other hand, when performing cleaning operation of adhered paint, the feed tube <NUM> can supply cleaning fluids such as thinner, air or the like from the paint passage toward the rotary atomizing head <NUM>. For example, the feed tube <NUM> is a double pipe formed by two coaxially arranged pipes. Further, the central passage of the double pipe is the paint passage, and the outer annular passage is the cleaning fluid passage (not shown).

The rotary atomizing head <NUM> is mounted to the tip of the rotating shaft <NUM>. The rotary atomizing head <NUM> is formed in a cup shape with a diameter extending from the base end side toward the tip side. The rotary atomizing head <NUM> rotates at a high speed together with the rotating shaft <NUM> by the air motor <NUM>. Thereby, the rotary atomizing head <NUM> sprays the paint and the like supplied from the feed tube <NUM>.

The shaping air ring <NUM> surrounding the rotary atomizing head <NUM>, is provided on the tip portion 3B side of the head portion <NUM>. The shaping air ring <NUM> ejects shaping air from a plurality of shaping air ejection holes (not shown). The shaping air adjusts the coating pattern of the paint to a desired size and shape while atomizing the paint sprayed from the rotary atomizing head <NUM>.

The valve device <NUM> is provided on the base end portion 3A side in the head portion <NUM>. As shown in <FIG>, the valve device <NUM> includes a base member <NUM> and four switching valves <NUM> to <NUM> described later. The valve device <NUM> controls the operations of supplying, stopping and exhausting and the like of various fluids.

The base member <NUM> constitutes the base of the valve device <NUM> and is formed as a metal block body. The base member <NUM> is mounted to the base end side in the head portion <NUM>. The base member <NUM> has a base end surface 12A facing the tip surface 2C of the arm portion <NUM>. For example, the base member <NUM> is provided with: a paint supply path 12B, which forms a part of the paint supply path to the feed tube <NUM>; a cleaning fluid passage through which cleaning fluid for cleaning the rotary atomizing head <NUM> circulates toward the feed tube <NUM>; a dump passage through which the previous color paint and the cleaning fluid circulate when exhausting the previous color paint remaining in the paint supply path 12B; and a tip cleaning passage (none is shown) through which cleaning fluid for cleaning the paint adhered to the tip of the feed tube <NUM> circulates.

In addition, the base member <NUM> is further provided with a pilot air passage <NUM> (shown only for the switching valve <NUM>) through which pilot air for operating the switching valves <NUM> to <NUM> circulates toward the switching valves <NUM> to <NUM>.

Four switching valves <NUM> to <NUM> are provided on the base member <NUM>. The four switching valves <NUM> to <NUM> are similarly configured. Therefore, the configuration of the switching valve <NUM> will be described and the description of the other switching valves <NUM> to <NUM> will be omitted. In addition, <NUM> to <NUM> or <NUM> or more switching valves may be provided.

As shown in <FIG>, the switching valve <NUM> is formed as a trigger valve that opens and closes the paint supply path 12B by pilot air. The switching valve <NUM> includes: a bottomed valve accommodating hole 13A formed in the base member <NUM>; a valve seat 13B extending from the bottom of the valve accommodating hole 13A toward the center side of the base member <NUM> and dividing the paint supply path 12B; a piston 13C movably accommodated in the valve accommodating hole 13A; a valve body 13D protruding from the piston 13C toward the valve seat 13B and seated on and/or unseated from the valve seat 13B; a cover body 13E closing the opening side of the valve accommodating hole 13A; and a spring member 13F disposed between the piston 13C and the cover body 13E and applying force on the valve body 13D in the valve closing direction via the piston 13C.

The valve accommodating hole 13A is defined by the piston 13C as a pilot chamber <NUM> on the bottom side and a spring chamber <NUM> on the cover body 13E side. The pilot chamber <NUM> is connected to a pilot air supply source (not shown) via a pilot air passage <NUM>.

The piston 13C is provided with a throttle passage 13J connecting the pilot chamber <NUM> and the spring chamber <NUM>. Compared with the supply amount of pilot air to the pilot chamber <NUM>, only a small amount of air circulates through the throttle passage 13J.

Therefore, when pilot air is supplied to the pilot chamber <NUM>, the piston 13C moves in the valve opening direction against the spring member 13F. On the other hand, upon the supply of pilot air to the pilot chamber <NUM> being stopped, the pilot air of the pilot chamber <NUM> flows out to the spring chamber <NUM> side through the throttle passage 13J. Thereby, the piston 13C moves in the valve closing direction by the applied force of the spring member 13F.

The cover body 13E is provided with a gas exhaust passage <NUM> connecting the spring chamber <NUM> and the valve mounting hole 3D of the head portion <NUM>. Thereby, the pilot air flowed into the spring chamber <NUM> flows out to the valve mounting hole 3D of the head portion <NUM> through the gas exhaust passage <NUM>. Moreover, the gas exhaust passage <NUM> together with the valve mounting hole 3D constitute a pilot air exhaust path <NUM> described later.

Here, the switching valve <NUM> is arranged such that the operation direction of the valve body 13D is the radial direction of the head portion <NUM>. The switching valves <NUM> to <NUM> are also arranged in the same manner as the switching valve <NUM>. Moreover, switching valves <NUM> to <NUM> are arranged at intervals in the circumferential direction of the head portion <NUM>. In the present embodiment, the radial direction of the head portion <NUM> is orthogonal to the axis of the head portion <NUM> and is the elongation direction of a straight line passing through the center of the head portion <NUM> (base member <NUM>) or the vicinity of the center of the head portion <NUM>.

Further, the switching valves <NUM> to <NUM> are formed as a cleaning fluid valve for opening and closing the above-mentioned cleaning fluid passage, a dump valve for opening and closing the dump passage, and a tip cleaning valve for opening and closing the tip cleaning passages.

The high voltage generator <NUM> is provided in the arm portion <NUM>. The high voltage generator <NUM> applies a high voltage to the paint supplied to the rotary atomizing head <NUM> through the valve device <NUM>, the air motor <NUM> and the rotating shaft <NUM>. The high voltage generator <NUM> includes for example a Cockcroft-Walton circuit. The high voltage generator <NUM> boosts the voltage supplied from a power supply device (not shown) to, for example, -60kV to -120kV. The output side of the high voltage generator <NUM> is electrically connected to a contact member <NUM> extending from the arm portion <NUM> to the base member <NUM>.

The cover portion <NUM> is formed as a resin cylindrical body covering the outer peripheral side of the head portion <NUM>. The base end side of the cover portion <NUM> is mounted to the outer periphery of the tip portion 2B of the arm portion <NUM>. In addition, the tip side of the cover portion <NUM> is mounted to the outer periphery of the shaping air ring <NUM>.

A cylindrical gap <NUM> is provided between the head portion <NUM> and the cover portion <NUM>. The cylindrical gap <NUM> is formed as a cylindrical space extending around the outer peripheral side of the head portion <NUM>. Here, the cylindrical gap <NUM> is a space isolated from the circulation path of the air exhausted from the air motor <NUM> and the path of the shaping air ejected from the shaping air ring <NUM>.

Thus, ozone may stay in the cylindrical gap <NUM>, and in this case, the outer peripheral surface of the head portion <NUM>, the inner peripheral surface of the cover portion <NUM> and the like in contact with the cylindrical gap <NUM> may be corroded by ozone. Therefore, the head portion <NUM> is provided with a pilot air introduction path <NUM> and a pilot air exhaust path <NUM> described later so as to exhaust ozone from the cylindrical gap <NUM>.

Next, configurations of the pilot air introduction path <NUM> and the pilot air exhaust path <NUM> that are characteristic parts of the present embodiment will be described.

The pilot air introduction path <NUM> is provided in the head portion <NUM>. The pilot air introduction path <NUM> is a passage that guides the pilot air exhausted from the switching valves <NUM> to <NUM> to the cylindrical gap <NUM>. The pilot air introduction path <NUM> includes exhaust passages <NUM> provided in the switching valves <NUM> to <NUM> (the exhaust passages of the switching valves <NUM> to <NUM> are not shown) and a valve mounting hole 3D of the head portion <NUM>. That is to say, in the present embodiment, four pilot air introduction paths <NUM> are provided over the valve device <NUM> and the head portion <NUM>. Therefore, the pilot air exhausted from the four switching valves <NUM> to <NUM> is supplied to the cylindrical gap <NUM> through the four pilot air introduction paths <NUM>. Thereby, the four pilot air introduction paths <NUM> can allow pilot air to flow into the cylindrical gap <NUM> over a wide range.

The pilot air exhaust path <NUM> is provided in the arm portion <NUM>. The pilot air exhaust path <NUM> is a passage exhausting the pilot air guided to the cylindrical gap <NUM> from the cylindrical gap <NUM> to the outside. The pilot air exhaust path <NUM> extends from the tip portion 2B of the arm portion <NUM> to the base end portion 2A. Moreover, the pilot air exhaust path <NUM> is opened to the outside of the arm portion <NUM> at the base end portion 2A of the arm portion <NUM>. Thereby, the pilot air exhausted from the pilot air exhaust path <NUM> does not affect the sprayed paint.

Specifically, one end of the pilot air exhaust path <NUM> in the longitudinal direction is opened at the tip portion 2B of the arm portion <NUM> and is in connection with the cylindrical gap <NUM>. On the other hand, the other end of the pilot air exhaust path <NUM> in the longitudinal direction is opened at the base end portion 2A of the arm portion <NUM> and opens up to the outside.

Here, the air flow generated by the pilot air introduction path <NUM> and the pilot air exhaust path <NUM> is described using reference numerals assigned to the switching valve <NUM>.

When pilot air is supplied to any one of the four switching valves <NUM> to <NUM>, a part of the supplied pilot air flows from the pilot chamber <NUM> to the spring chamber <NUM> via the throttle passage 13J. The pilot air flowed into the spring chamber <NUM> flows out to the valve mounting hole 3D of the head portion <NUM> through the gas exhaust passage <NUM>. As a result, the pilot air introduction path <NUM> including the gas exhaust passage <NUM> and the valve mounting hole 3D can guide the pilot air to the cylindrical gap <NUM>.

On the other hand, the pilot air exhaust path <NUM> can exhaust the pilot air flowing through the cylindrical gap <NUM> from the base end portion 2A of the arm portion <NUM> to the outside.

In this manner, supply of pilot air to the cylindrical gap <NUM> through the pilot air introduction path <NUM> and exhaust of pilot air exhausted from the cylindrical gap <NUM> through the pilot air exhaust path <NUM> generate air flows in the cylindrical gap <NUM>. The air flow also propagates to the tip side of the cylindrical gap <NUM>. Thereby, the pilot air introduction path <NUM> and the pilot air exhaust path <NUM> can generate an air flow in the cylindrical gap <NUM> using the pilot and exhaust the ozone in the cylindrical gap <NUM> together with the air.

Next, a structure configured to exhaust the ozone remaining in the planar gap <NUM> to the outside will be described.

A first dual pipeline <NUM> is provided in the arm portion <NUM>. The first dual pipeline <NUM> extends between the base end portion 2A of the arm portion <NUM> and the planar gap <NUM>. The first dual pipeline <NUM> is formed as a pipe member having a dual structure with an inner passage and an outer passage.

The inner passage of the first dual pipeline <NUM> is a compressed air exhaust path <NUM> as a compressed air flow path through which compressed air (turbine air) exhausted from the turbine 6B of the air motor <NUM> circulates. The upstream side of the compressed air exhaust path <NUM> is connected to the air motor <NUM>. The downstream side of the compressed air exhaust path <NUM> opens up to the outside at the base end portion 2A of the arm portion <NUM>.

In addition, the outer passage of the first dual pipeline <NUM> is a purge air supply path <NUM> supplying purge air to the planar gap <NUM>. The upstream side of the purge air supply path <NUM> is connected to the supply source (not shown) of purge air (compressed air). The downstream side of the purge air supply path <NUM> is connected to a position in the vicinity of the outer peripheral side of the planar gap <NUM>.

A second dual pipeline <NUM> is provided in the arm portion <NUM>. The second dual pipeline <NUM> extends between the base end portion 2A of the arm portion <NUM> and the planar gap <NUM> in the same manner as the first dual pipeline <NUM>. The second dual pipeline <NUM> is formed as a pipe member having a dual structure with an inner passage and an outer passage.

The inner passage of the second dual pipeline <NUM> is a compressed air exhaust path <NUM> as a compressed air flow path through which compressed air exhausted from the turbine 6B of the air motor <NUM> circulates. The upstream side of the compressed air exhaust path <NUM> is connected to the air motor <NUM>. The downstream side of the compressed air exhaust path <NUM> opens up to the outside at the base end portion 2A of the arm portion <NUM>. Further, either of the inner passage of the first dual pipeline <NUM> and the inner passage of the second dual pipeline <NUM> may be used as the compressed air supply path through which compressed air circulates toward the turbine 6B.

In addition, the outer passage of the second dual pipeline <NUM> is a purge air exhaust path <NUM> exhausting purge air from the planar gap <NUM> to the outside. The upstream side of the purge air exhaust path <NUM> is connected to a position in the vicinity of the outer peripheral side of the planar gap <NUM>. The downstream side of the purge air exhaust path <NUM> opens up to the outside at the base end portion 2A of the arm portion <NUM>.

Here, the air flow generated by the purge air supply path <NUM> and the purge air exhaust path <NUM> will be described.

Upon purge air being supplied through the purge air supply path <NUM>, the purge air flows into the planar gap <NUM>. The purge air flowed into the planar gap <NUM> flows toward the purge air exhaust path <NUM> through the planar gap <NUM> and is exhausted to the outside through the purge air exhaust path <NUM>. Thereby, ozone remaining in the planar gap <NUM> can be exhausted to the outside using the purge air.

Further, the purge air supply path <NUM> and the purge air exhaust path <NUM> are opened to the planar gap <NUM> at positions separated from each other. Thereby, as shown by arrows in <FIG>, the purge air flowing into the planar gap <NUM> from the purge air supply path <NUM> can circulate throughout the planar gap <NUM> and ozone can be effectively exhausted.

The electrostatic coating device <NUM> according to the present embodiment has the configuration as described above. Next, the operation when coating on the coated object <NUM> by the electrostatic coating device <NUM> will be described.

Compressed air is supplied to the turbine 6B of the air motor <NUM> through the compressed air supply path, such that the rotating shaft <NUM> and the rotary atomizing head <NUM> rotate together with the turbine 6B at a high speed. In addition, the compressed air (used air) rotating the turbine 6B is exhausted to the outside through the compressed air exhaust paths <NUM> and <NUM>.

In addition, a high voltage is applied from the high voltage generator <NUM> to the base member <NUM> of the valve device <NUM> via the contact member <NUM>. Thereby, the high voltage is applied to the feed tube <NUM> via the base member <NUM>, the motor case 6A of the air motor <NUM> and the rotating shaft <NUM>.

In this state, pilot air is supplied from the pilot air passage <NUM> to the pilot chamber <NUM> of the switching valve <NUM>, opening the valve body 13D. Thereby, the paint supplied from the paint supply source circulates in the paint supply path 12B of the base member <NUM> and the paint passage of the feed tube <NUM>, and is sprayed from the rotary atomizing head <NUM> toward the coated object <NUM> (see <FIG>).

When spraying paint, the paint flowing through the paint passage is electrically charged with high voltage by the high voltage applied to the feed tube <NUM>. Thereby, the electrically charged paint particles sprayed from the rotary atomizing head <NUM> can be effectively coated to the coated object <NUM> having the ground potential. In addition, the shaping air ring <NUM> can adjust the spray pattern of the paint by spraying shaping air toward the sprayed paint.

When the switching valve <NUM> is opened by the pilot air, a part of the pilot air is guided to the cylindrical gap <NUM> through the pilot air introduction path <NUM> (the valve mounting hole 3D of the head portion <NUM> and the gas exhaust passage <NUM> of the switching valve <NUM>). In addition, the pilot air guided to the cylindrical gap <NUM> is exhausted from the cylindrical gap <NUM> to the outside through the pilot air exhaust path <NUM>.

The operation in which a part of the pilot air flows through the cylindrical gap <NUM> is similarly performed when the pilot air is supplied to the switching valves <NUM> to <NUM>.

That is to say, the cleaning fluid valve is opened by pilot air after spraying paint. Thereby, the cleaning fluid is supplied to the rotary atomizing head <NUM> through the paint supply path 12B and the feed tube <NUM>, cleaning the paint adhered to the paint supply path 12B, the feed tube <NUM> and the rotary atomizing head <NUM>.

In addition, after cleaning the paint supply path 12B, the feed tube <NUM> and the rotary atomizing head <NUM>, the dump valve is opened by pilot air. Thereby, waste liquid including paint remaining in the paint supply path 12B or the like and the cleaning fluid is exhausted.

In addition, the tip cleaning valve is opened by the pilot air after or in parallel with the exhaust of the waste liquid. Thereby, paint adhering to the tip of the feed tube <NUM> is cleaned.

Here, when the high voltage generated by the high voltage generator <NUM> via the contact member <NUM> is applied to the base member <NUM> or the like of the valve device <NUM>, ozone is released from the metal base member <NUM> electrically charged with high voltage and the rotating shaft <NUM>. The ozone released from the base member <NUM> and the rotating shaft <NUM> is exhausted together with the exhaust gas of compressed air having driven the turbine 6B of the air motor <NUM> and the shaping air sprayed from the shaping air ring <NUM>.

However, in the electrostatic coating device <NUM>, part of the ozone generated in the motor case 6A of the air motor <NUM>, the base member <NUM> of the valve device <NUM> and the like flows into the cylindrical gap <NUM> between the head portion <NUM> and the cover portion <NUM> and the planar gap <NUM> between the tip surface 2C of the arm portion <NUM> and the base end face 3C of the head portion <NUM> and stays. In this way, the stayed ozone may corrode the arm portion <NUM>, the head portion <NUM>, the cover portion <NUM> and the like made of resin.

However, according to the present embodiment, a cylindrical gap <NUM> is provided around the outer peripheral side of the head portion <NUM> between the head portion <NUM> and the resin cover portion <NUM> covering the outer peripheral side of the head portion <NUM>. Moreover, the head portion <NUM> is provided with a pilot air introduction path <NUM> guiding the pilot air exhausted from the switching valves <NUM> to <NUM> to the cylindrical gap <NUM>. In addition, the arm portion <NUM> is provided with a pilot air exhaust path <NUM> exhausting the pilot air from the cylindrical gap <NUM> to the outside.

Accordingly, a part of the pilot air opening the switching valves <NUM> to <NUM> is guided to the cylindrical gap <NUM> through the pilot air introduction path <NUM>, and is exhausted to the outside from the cylindrical gap <NUM> through the pilot air exhaust path <NUM>.

The pilot air guided to the cylindrical gap <NUM> through the pilot air introduction path <NUM> flows through the cylindrical gap <NUM>, thereby generating a flow in the ozone remaining in the cylindrical gap <NUM>, and the ozone is exhausted to the outside from the pilot air exhaust path <NUM>.

In addition, a part of the pilot air guided to the cylindrical gap <NUM> is exhausted to the outside from the pilot air exhaust path <NUM> immediately after being guided. However, the flow of pilot air from the pilot air exhaust path <NUM> toward the pilot air exhaust path <NUM> generates a flow in the cylindrical gap <NUM> due to pressure difference, such that ozone in the cylindrical gap <NUM> circulates toward the pilot air exhaust path <NUM>.

As a result, ozone can be prevented from staying in the cylindrical gap <NUM> where there is no air flow and the durability of resin components such as the head portion <NUM> and the cover portion <NUM> can be improved.

In addition, the pilot air exhaust path <NUM> extends from the tip portion 2B of the arm portion <NUM> to the base end portion 2A and is opened to the outside of the arm portion <NUM> at the base end portion 2A of the arm portion <NUM>. Thereby, the exhaust containing ozone can be prevented from interfering with the coating, thus the coating quality can be improved.

A plurality of switching valves <NUM> to <NUM> are provided at intervals in the circumferential direction of the head portion <NUM> such that the operation direction of the valve body 13D is the radial direction of the head portion <NUM>. Thereby, it is possible to effectively exhaust the ozone remaining over a wide range by the pilot air exhausted from the plurality of switching valves <NUM> to <NUM>.

On the other hand, in the electrostatic coating device <NUM> according to the present embodiment, the tip portion 2B of the arm portion <NUM> and the base end portion 3A of the head portion <NUM> are mounted facing each other with the sealing member <NUM> sandwiched therebetween in the periphery. Moreover, the arm portion <NUM> is provided with a purge air supply path <NUM> supplying purge air to the planar gap <NUM> between the tip portion 2B of the arm portion <NUM> and a base end portion 3A of the head portion <NUM>, and a purge air exhaust path <NUM> exhausting the purge air from the planar gap <NUM> to the outside.

Therefore, purge air is regularly or always supplied to the planar gap <NUM> through the purge air supply path <NUM> and the purge air in the planar gap <NUM> is exhausted to the outside through the purge air exhaust path <NUM>. Thereby, ozone can be prevented from staying in the planar gap <NUM> where there is no air flow and the durability of resin components such as the arm portion <NUM> and the sealing member <NUM> can be improved.

Moreover, the opening positions of the purge air supply path <NUM> and the purge air exhaust path <NUM> to the planar gap <NUM> are arranged on radially opposite sides of the furthest planar gap <NUM> where the opposite sides are most distant from each other. Thereby, the purge air supplied from the purge air supply path <NUM> can circulate over a wide range of the planar gap <NUM> and the exhaust efficiency of ozone can be improved.

Claim 1:
An electrostatic coating device (<NUM>) including:
an arm portion (<NUM>) having base end side mounted to an operating device;
a head portion (<NUM>) provided at a tip side of the arm portion;
an air motor (<NUM>) provided at the head portion and powered by compressed air,
a hollow rotating shaft (<NUM>) rotatably supported by the air motor and having a tip protrudes forward from the air motor;
a feed tube (<NUM>) extending through an inside of the rotating shaft to the tip of the rotating shaft for supplying paint;
a rotary atomizing head (<NUM>) mounted at the tip of the rotating shaft and configured to spray the paint supplied from the feed tube to a coated object;
a valve device (<NUM>) provided at the head portion and provided with a switching valve (<NUM>-<NUM>) including a trigger valve (<NUM>) for opening and closing a paint supply path (12B) to the feed tube by pilot air;
a high voltage generator (<NUM>) provided at the arm portion and configured to apply a high voltage to the paint supplied to the rotary atomizing head through the valve device, the air motor and the rotating shaft; and
a cover portion (<NUM>) formed as a resin cylindrical body covering an outer peripheral side of the head portion,
the electrostatic coating device being characterized in that:
a cylindrical gap (<NUM>) is provided between the head portion and the cover portion, the cylindrical gap surrounding the outer peripheral side of the head portion,
the head portion is provided with a pilot air introduction path (<NUM>) guiding the pilot air exhausted from the switching valve to the cylindrical gap,
the arm portion is provided with a pilot air exhaust path (<NUM>) exhausting the pilot air from the cylindrical gap to the outside.