JP2017060906A - Coating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent atomization failure of paint by restraining a flow rate of exhaust air of flowing in a hollow space of a hollow rotary shaft from an exhaust space formed of an exhaust passage, an exhaust port and an exhaust chamber, and to prevent abnormal vibration by restraining turbulence of the pressure distribution of a leakage air inflow space.SOLUTION: A seal ring 23 is provided for blocking up an annular flow passage 22 reaching a hollow rotary shaft 4 by passing through a clearance between a feed tube 6 and a back face cover 11, and a cylindrical opening part 21 is formed by projecting forward so as to be inserted into a hollow space 29 from the rear end side of the hollow rotary shaft 4, and a narrow clearance of becoming a noncontact seal 24 is formed between its outer peripheral surface 21b and a hollow rotary shaft inner peripheral surface 4a, and a pressure release flow passage F1 for communicating a leakage air inflow space 25 and an exhaust chamber 13, is formed near the center from an exhaust port 12 of the back face cover 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating machine that atomizes and sprays paint with a rotary atomizing head that is driven to rotate by an air motor.

  As shown in FIG. 7, this type of general coating machine A has a rotary atomizing head 5 attached to the tip of a hollow rotary shaft 4 that is driven to rotate at high speed by an air motor 3 built in the coating machine body 2. The coating material supplied through the feed tube 6 inserted into the hollow space 29 of the hollow rotary shaft 4 is sprayed by being atomized by the rotary atomizing head 5.

  The air motor 3 mounted on the coating machine main body 2 has an air in which a hollow rotating shaft 4 protruded from the front end side of a motor housing 7 is supported by a radial bearing 8 and a turbine blade 9b is formed on an outer peripheral portion of a turbine wheel 9a. A turbine 9 is integrally formed on the rear end side of the hollow rotary shaft 4.

An air supply port 10 for blowing drive air (compressed air) to the turbine blade 9 b is formed around the air turbine 9, and the rear cover 11 fixed to the motor housing 7 so as to cover the air turbine 9 includes a turbine An exhaust port 12 is formed through which exhaust air discharged through the exhaust passage 28 formed on the inner peripheral surface of the blade 9b is discharged rearward.
Further, an exhaust chamber 13 is formed in the interior of the coating machine 2 behind the back cover 11 of the air motor 3, and an exhaust hose (not shown) or the like is connected to the exhaust chamber 13 to paint the exhaust air. The machine body 2 is discharged outside.

  Further, as shown in FIG. 8, a feed tube 6 for supplying paint to the rotary atomizing head 5 (see FIG. 7) is inserted into the rear cover 11 from the exhaust chamber 13 side into the hollow space 29 of the hollow rotary shaft 4. A cylindrical opening 31 is formed so as to protrude rearward.

Here, as shown in FIG. 7, while supplying drive air to the air motor 3 and driving the rotary atomizing head 5 at a normal rotational speed (for example, about 2 to 40,000 rpm), the paint is supplied through the feed tube 6. Then, the paint is centrifugally atomized by the rotary atomizing head 5 and sprayed.
In addition, when spraying paint with a large discharge amount, it is necessary to drive the rotary atomizing head 5 at a higher speed (for example, about 4 to 60000 rpm) in order to maintain atomization. It is necessary to supply a large amount of air at high pressure.

  However, when the amount of drive air supplied increases, the pressure loss in the exhaust path increases, and the pressure in the space formed by the exhaust path 28, the exhaust port 12, and the exhaust chamber 13 (hereinafter referred to as "exhaust space") increases. Therefore, a part of the exhaust air flows from the exhaust space through the hollow space 29 of the hollow rotary shaft 4 into the rotary atomizing head 5 to increase the pressure in the rotary atomizing head 5 and Causes atomization defects.

For this reason, a mechanism has been proposed in which an exhaust port for communicating the inside and the outside of the hollow rotary shaft is provided on the side surface of the hollow rotary shaft to release the pressure in the hollow space (see Patent Document 1).
However, according to the experiment of the present inventor, even when an exhaust port is provided in the hollow rotating shaft, when the amount of inflow into the hollow space increases, the pressure of the exhaust space and the hollow space does not sufficiently decrease. The above problem could not be solved.

For this reason, the present inventors have conceived of blocking the air flow between the exhaust space and the hollow space 29 of the hollow rotary shaft 4.
As shown in FIG. 8, the exhaust chamber 13 and the hollow space 29 communicate with each other via an annular flow path 32 formed in a gap between the outer peripheral surface of the feed tube 6 and the inner peripheral surface of the cylindrical opening 31. However, it is necessary to ensure a certain size (about 1 mm interval) for the clearance that becomes the annular flow path 32 for the convenience of the assembly work of the coating machine.

Therefore, in order to block the annular flow path 32 while maintaining the distance between the outer peripheral surface of the feed tube 6 and the inner peripheral surface of the cylindrical opening 31, a seal such as an O-ring is used as shown in FIG. A coating machine B in which the ring 33 was provided and the exhaust chamber 13 and the hollow space 29 were shut off was prototyped.
When the seal ring 33 is provided in the annular flow path 32 and blocked, the rigid members of the feed tube 6 and the cylindrical opening 31 do not come into contact with each other. Even if the exhaust space becomes high pressure by supplying a large amount of drive air at a high pressure, the exhaust air does not flow in a large amount into the hollow space 29, so that the fine atomization of the paint does not occur.

However, in order to increase the rotational speed of the rotary atomizing head further to the maximum allowable rotational speed (for example, about 6 to 80000 rpm), when drive air is supplied at a higher pressure and a larger supply amount, it is rare, but abnormal vibration Was sometimes observed.
The cause of this abnormal vibration is thought to be due to an increase in the amount of air flowing through the leaked air inflow space 34 formed in the gap between the back cover 11 and the turbine wheel 9a and the disturbance of the pressure distribution in the space 34.
In other words, in a coating machine having a conventional structure in which the seal ring 33 is not mounted, air flows from the exhaust space toward the hollow space 29 because the pressure in the hollow space 29 is lower than that in the exhaust space. Many of them flowed through the annular flow path 32 having a larger gap than the leakage air inflow space 34.
However, the annular flow path 32 communicating with the exhaust chamber 13 and the hollow space 29 is blocked by the seal ring 33, so that the flow path to the hollow space 29 is limited to the leakage air inflow space 34, and the flow rate flowing therethrough increases. At the same time, the pressure increases, and it is presumed that the pressure distribution in the leaked air inflow space 34 is disturbed due to the rotation of the air turbine 9, and abnormal vibration is likely to occur.

International Publication No. 2015/004966 Pamphlet

  Accordingly, the present invention prevents the paint atomization failure by suppressing the flow rate of the exhaust air flowing into the hollow space of the hollow rotary shaft from the exhaust space formed by the exhaust path, the exhaust port, and the exhaust chamber, and leaking air. It is a technical problem to prevent abnormal vibration by suppressing the disturbance of the pressure distribution in the inflow space.

In order to solve this problem, the present invention is provided with a rotary atomizing head for atomizing paint at the tip of a hollow rotating shaft of an air motor built in the coating machine body,
In the air motor, an air turbine having a turbine blade formed on the outer peripheral portion of the turbine wheel is provided on the rear end side of the hollow rotary shaft, and an exhaust port for exhausting the exhaust air of the air motor to the rear is formed in the housing of the air motor. The rear cover is attached to cover the air turbine,
The rear space of the back cover is formed as an exhaust chamber for discharging the exhaust air of the air motor to the outside of the main body of the paint machine, and the gap between the back cover and the turbine wheel is inflow of leaked air from which exhaust air leaks. It ’s a space,
In the coating machine in which the cylindrical cover part through which the feed tube for supplying paint to the rotary atomizing head is inserted into the hollow space of the hollow rotary shaft from the exhaust chamber side is formed in the back cover.
A seal ring is provided to close an annular flow path that reaches the hollow rotating shaft through the gap between the feed tube and the back cover,
The cylindrical opening is formed to protrude forward so as to be inserted into the hollow space from the rear end side of the hollow rotating shaft, and between the outer peripheral surface and the inner peripheral surface of the hollow rotating shaft. A narrow clearance is formed,
A plurality of pressure relief passages that connect the leakage air inflow space and the exhaust chamber are formed closer to the center than the exhaust port of the back cover.

  According to the present invention, the annular flow path that passes through the gap between the feed tube and the back cover and reaches the hollow rotary shaft is blocked by the seal ring, and therefore passes through the annular flow path from the exhaust chamber to the hollow space of the hollow rotary shaft. Exhaust air will not flow.

  Further, the cylindrical opening is formed to protrude forward so as to be inserted into the hollow space from the rear end side of the hollow rotary shaft, and becomes a non-contact seal between the outer peripheral surface and the inner peripheral surface of the hollow rotary shaft. Since the narrow clearance is formed, it is possible to suppress the exhaust air from flowing into the hollow space of the hollow rotary shaft through the leaked air inflow space or the pressure relief passage.

  Further, since the exhaust chamber and the leaked air inflow space are communicated with each other via a pressure relief passage, the pressure of the leaked air inflow space is synchronized with the pressure of the exhaust chamber with relatively little fluctuation, There is no disturbance in the pressure distribution, and no abnormal vibration occurs when the rotary atomizing head is rotated at the maximum allowable rotation speed.

Explanatory drawing which shows the principal part of the coating machine which concerns on this invention. Explanatory drawing which shows the principal part of the other Example which concerns on this invention. Explanatory drawing which shows the principal part of the further another Example which concerns on this invention. Explanatory drawing which shows the principal part of the further another Example which concerns on this invention. Explanatory drawing which shows the principal part of the further another Example which concerns on this invention. Explanatory drawing which shows the principal part of the further another Example which concerns on this invention. Explanatory drawing which shows the structure of a common coating machine. Explanatory drawing which shows the principal part of the conventional coating machine. Explanatory drawing which shows the principal part of the conventional coating machine.

The present invention prevents the paint atomization failure by suppressing the flow rate of the exhaust air flowing into the hollow space of the hollow rotary shaft from the exhaust space composed of the exhaust path, the exhaust port, and the exhaust chamber, and also prevents the leakage air inflow space. In order to achieve the object of preventing abnormal vibration by suppressing the disturbance of the pressure distribution, the following configuration is provided.
That is, a rotary atomizing head for atomizing paint is attached to the tip of the hollow rotary shaft of an air motor built in the coating machine body,
In the air motor, an air turbine having a turbine blade formed on the outer peripheral portion of the turbine wheel is provided on the rear end side of the hollow rotary shaft, and an exhaust port for exhausting the exhaust air of the air motor to the rear is formed in the housing of the air motor. The rear cover is attached to cover the air turbine,
The rear space of the back cover is formed as an exhaust chamber for discharging the exhaust air of the air motor to the outside of the main body of the paint machine, and the gap between the back cover and the turbine wheel enters the leaked air into which the exhaust air leaks. It ’s a space,
In the coating machine in which the cylindrical cover part through which the feed tube for supplying paint to the rotary atomizing head is inserted into the hollow space of the hollow rotary shaft from the exhaust chamber side is formed in the back cover.
A seal ring is provided to close an annular flow path that reaches the hollow rotating shaft through the gap between the feed tube and the back cover,
The cylindrical opening is formed to protrude forward so as to be inserted into the hollow space from the rear end side of the hollow rotating shaft, and between the outer peripheral surface and the inner peripheral surface of the hollow rotating shaft. A narrow clearance is formed,
A pressure relief passage that connects the leakage air inflow space and the exhaust chamber is formed closer to the center than the exhaust port of the back cover.

FIG. 1 is an explanatory view showing a main part of a coating machine T1 according to the present invention, and common components are common to the coating machine shown in FIG.
The cylindrical opening 21 formed in the back cover 11 of the motor housing 7 is formed to protrude forward so as to be inserted in a non-contact state from the rear end side of the hollow rotary shaft 4. The cylindrical opening 21 may be formed integrally with the back cover 11 or may be attached and fixed integrally to the back cover 11 as an accessory.

A gap between the outer peripheral surface 6a of the feed tube 6 and the inner peripheral surface 21a of the cylindrical opening 21 is formed as an annular flow path 22 opened to the exhaust chamber 13, and the opening on the hollow rotary shaft 4 side is an O-ring. Etc. are sealed with a seal ring 23.
The seal ring 23 may be provided on the inner peripheral surface 21 a of the cylindrical opening 21 or may be provided on the outer peripheral surface 6 a of the feed tube 6.

Between the outer peripheral surface 21 b of the cylindrical opening 21 and the inner peripheral surface 4 a of the hollow rotary shaft 4, a narrow clearance that forms a non-contact seal 24 is formed.
Since the back cover 11 is fixed to the motor housing 7, the cylindrical opening 21 formed in the back cover 11 can be centered with high accuracy with respect to the inner peripheral surface 4 a of the hollow rotary shaft 4.
Therefore, the narrow clearance that becomes the non-contact seal 24 can be designed with an accuracy of 0.1 mm or less. In this example, the gap is designed to be 0.3 mm or less according to the pressure loss caused by the non-contact seal 24. ing.

  A gap between the back cover 11 and the turbine wheel 9a is a leaked air inflow space 25 into which leaked air of exhaust air that has not been discharged from the exhaust port 12 flows, and is closer to the center (rotation) than the exhaust port 12 of the back cover 11 Near the center, a plurality of pressure relief passages F <b> 1 that connect the leakage air inflow space 25 and the exhaust chamber 13 are formed.

  In this example, the pressure relief flow path F <b> 1 is formed so as to radially penetrate the inside and outside of the cylindrical opening 21 from the rear part of the annular flow path 22 toward the leakage air inflow space 25.

The above is one configuration example of the present invention, and the operation thereof will be described next.
When drive air is supplied to the air motor 3, the drive air is blown from the air supply port 10 to the turbine blade 9b and the turbine 9 is rotated, whereby the hollow rotary shaft 4 and the rotary atomizing head 5 are driven to rotate at high speed.
Most of the exhaust air is discharged rearward from the exhaust port 12, passes through the exhaust chamber 13, and is led to the outside by an exhaust hose (not shown) or the like.
A part of the exhaust air flows into the leaked air inflow space 25 in the gap between the turbine wheel 9 a and the back cover 11.

At this time, the annular flow path 22 formed in the gap between the feed tube 6 and the cylindrical opening 21 is closed on the hollow rotary shaft 4 side by the seal ring 23, so that the exhaust air passes through the annular flow path 22. There is no flow into the hollow space 29 of the hollow rotary shaft 4.
In addition, since the non-contact seal 24 is formed in the flow path that passes through the gap between the outer peripheral surface of the cylindrical opening 21 and the inner peripheral surface of the hollow rotary shaft 4 and reaches the hollow space 29, the leakage air inflow space 25 and It is possible to suppress the exhaust air that has flowed into the pressure relief flow path F <b> 1 from flowing into the hollow rotary shaft 4.
Therefore, a large amount of exhaust air does not flow into the hollow space 29, and a poor atomization of the paint is prevented.

  Further, the exhaust chamber 13 and the leaked air inflow space 25 are communicated with each other via the pressure relief flow path F1, and the volume of the exhaust chamber 13 is sufficiently larger than the leaked air inflow space 25. It synchronizes with the pressure of the exhaust chamber 13 with relatively little fluctuation, and there is no disturbance in the pressure distribution of the leaking air inflow space 25, and abnormal vibration occurs when the rotary atomizing head is rotated at the maximum allowable rotational speed. It does not occur.

  FIG. 2 is an explanatory view showing a main part of another embodiment. 1 and 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the coating machine T2 of this example, the feed tube 6 is formed with a stepped portion 6b that comes into contact with the rear end surface of the cylindrical opening 21, and an O-ring or the like is formed at the contact between the stepped portion 6b and the cylindrical opening 21. The seal ring 23 is attached.
The back cover 11 is formed with a plurality of pressure relief passages F2 communicating with the exhaust chamber 13 and the leakage air inflow space 25 so as to be positioned outside the seal ring 23.

  In this example, as in the first embodiment, the annular flow path 22 communicating the exhaust chamber 13 and the hollow rotary shaft 4 is blocked by the seal ring 23, so that the exhaust air passes through the annular flow path 22 and the hollow space of the hollow rotary shaft 4. 29 and the non-contact seal 24 is formed between the outer peripheral surface of the cylindrical opening 21 and the inner peripheral surface of the hollow rotary shaft 4, so that the exhaust air flowing into the leaked air inflow space 25 The inflow to the hollow rotary shaft 4 is suppressed, thereby preventing the atomization failure.

  Further, since the leaked air inflow space 25 and the exhaust chamber 13 are communicated with each other by the pressure relief flow path F2, the pressure of the leaked air inflow space 25 is synchronized with the pressure of the exhaust chamber 13 with relatively little fluctuation. There is no disturbance in the pressure distribution in the inflow space 25, and no abnormal vibration occurs when the rotary atomizing head is rotated at the maximum allowable rotation speed.

FIG. 3 is an explanatory view showing a main part of another embodiment. 2 and 7 are denoted by the same reference numerals, and detailed description thereof is omitted.
In the coating machine T3 of this example, the cylindrical opening 21 is formed so as to protrude to the rear of the back cover 11, and a cylindrical shape that surrounds the rear-side outer peripheral surface 21c of the cylindrical opening 21 at the proximal end portion of the feed tube 6. A cover 26 is formed.
The cylindrical cover 26 may be integrally formed with the feed tube 6 or may be integrally attached and fixed to the proximal end portion of the feed tube 6 as an accessory part.

  A seal ring 23 is provided in a gap between the back side outer peripheral surface 21c of the cylindrical opening 21 and the inner peripheral surface 26a of the cylindrical cover 26, and the exhaust chamber 13 and the hollow rotary shaft 4 are communicated with each other by the seal ring 23. The back surface cover 11 is formed with a plurality of pressure relief passages F3 communicating with the exhaust chamber 13 and the leakage air inflow space 25 so as to be located outside the seal ring 23. Has been. Other configurations are the same as those of the second embodiment shown in FIG.

  Also in this example, the annular flow path 22 communicating the exhaust chamber 13 and the hollow rotary shaft 4 is blocked by the seal ring 23, so that the exhaust air does not flow into the hollow space 29 in the hollow rotary shaft 4 through the annular flow path 22. Further, since a non-contact seal 24 is formed between the outer peripheral surface of the cylindrical opening 21 and the inner peripheral surface of the hollow rotary shaft 4, the exhaust air flowing into the leaked air inflow space 25 is directed to the hollow rotary shaft 4. Inflow is suppressed, thereby preventing atomization defects.

  Further, since the leaked air inflow space 25 and the exhaust chamber 13 are communicated with each other by the pressure relief flow path F3, the pressure of the leaked air inflow space 25 is synchronized with the pressure of the exhaust chamber 13 with relatively little fluctuation. There is no disturbance in the pressure distribution in the inflow space 25, and no abnormal vibration occurs when the rotary atomizing head is rotated at the maximum allowable rotation speed.

Further, as in the coating machine T4 shown in FIG. 4, the pressure relief flow path F4 that communicates the leakage air inflow space 25 and the exhaust chamber 13 passes vertically through the cylindrical opening 21 substantially parallel to the hollow rotary shaft 4. In this way, the required number of the flow paths F4 are opened to the leakage air inflow space 25 on the front side of the back cover 11, and the rear end is opened to the exhaust chamber 13 on the back side of the cylindrical opening 21. May be.
Other configurations are the same as those in FIGS. 1 and 7.

Furthermore, as in the coating machines T5 and T6 shown in FIGS. 5 and 6, the back side of the back cover 11 may be formed flat and the cylindrical opening 21 may not protrude rearward.
Here, in the coating machine T5, the pressure relief flow path F5 communicating with the leakage air inflow space 25 and the exhaust chamber 13 is changed from the seal ring 23 of the annular flow path 22 to the leakage air inflow space 25 in the same manner as in FIG. It is formed so as to radiate through the inside and outside of the cylindrical opening 21 and the other configurations are the same as those in FIGS. 1 and 7.
Further, the coating machine T6 requires that the pressure relief flow path F6 that communicates between the leakage air inflow space 25 and the exhaust chamber 13 penetrates the front and back of the back cover 21 substantially parallel to the hollow rotary shaft 4 as in FIG. The front end of the flow path F6 is opened to the leakage air inflow space 25 on the front side of the back cover 11, the rear end is opened to the exhaust chamber 13 on the back side of the back cover 11, The configuration is the same as in FIGS. 4 and 7.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a use of a coating machine that rotates a rotary atomizing head that atomizes a paint by an air motor built in a coating machine body.

T1-T6 Painter 2 Painter body
3 Air motor
4 Hollow rotating shaft
5 Rotating atomizing head
6 Feed tube
7 Housing 9 Air turbine 9a Turbine wheel 9b Turbine blade 11 Back cover 12 Exhaust port 13 Exhaust chamber 21 Cylindrical opening 22 Annular flow path 23 Seal ring 24 Non-contact seal 25 Leaked air inflow space F1 to F6 Pressure relief flow path

Claims (5)

A rotary atomizing head that atomizes the paint is attached to the tip of the hollow rotary shaft of the air motor built in the coating machine body,
In the air motor, an air turbine having a turbine blade formed on the outer peripheral portion of the turbine wheel is provided on the rear end side of the hollow rotary shaft, and an exhaust port for exhausting the exhaust air of the air motor to the rear is formed in the housing of the air motor. The rear cover is attached to cover the air turbine,
The rear space of the back cover is formed as an exhaust chamber for discharging the exhaust air of the air motor to the outside of the main body of the paint machine, and the gap between the back cover and the turbine wheel is a leak into which exhaust air leaks. It is an air inflow space,
In the coating machine in which the cylindrical cover part through which the feed tube for supplying paint to the rotary atomizing head is inserted into the hollow space of the hollow rotary shaft from the exhaust chamber side is formed in the back cover.
A seal ring is provided to close an annular flow path that reaches the hollow rotating shaft through the gap between the feed tube and the back cover,
The cylindrical opening is formed to protrude forward so as to be inserted into the hollow space from the rear end side of the hollow rotating shaft, and between the outer peripheral surface and the inner peripheral surface of the hollow rotating shaft. A narrow clearance is formed,
A coating machine, characterized in that a pressure relief passage that connects the leakage air inflow space and the exhaust chamber is formed closer to the center than the exhaust port of the back cover. An annular channel formed by a gap between the outer peripheral surface of the feed tube and the inner peripheral surface of the cylindrical opening is opened to the exhaust chamber, and the seal ring is provided on the hollow rotary shaft side of the annular channel,
The coating machine according to claim 1, wherein the pressure relief passage is formed so as to penetrate a cylindrical opening from the annular passage behind the seal ring toward the leakage air inflow space. A step portion that is in contact with the rear end surface of the cylindrical opening is formed in the feed tube, and the seal ring is arranged at the contact portion of the feed tube and the cylindrical opening,
The coating machine according to claim 1, wherein the pressure relief passage is formed outside the seal ring. The cylindrical opening protrudes rearward of the back cover, and a cylindrical cover surrounding the back side outer peripheral surface of the cylindrical opening is formed at the base end of the feed tube,
The seal ring is provided in a gap between the outer peripheral surface on the back side of the cylindrical opening and the inner peripheral surface of the cylindrical cover, and the annular flow path communicating the exhaust chamber and the hollow rotary shaft is blocked. The coating machine according to claim 1. The coating machine according to any one of claims 1 to 4, wherein a narrow clearance forming the non-contact seal is 0.3 mm or less.

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