JP2017035658A - Coating machine and rotary atomization head used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating machine capable of smoothly discharging air in a space of an exhaust channel which communicates an inner part and an outer part of a hollow rotation shaft which allows a rotary atomization head to be attached to a tip thereof by actuating a sufficient centrifugal force to the exhaust channel.SOLUTION: A cylindrical connection mechanism 22 which is attached and fixed to a hollow rotation shaft 12 of an air motor 11, a nozzle insertion port 23 to which a tip of a feed tube 13 inserted into the hollow rotation shaft 12 is inserted and a coating material chamber 24 which receives supply of coating material from the feed tube 13 are formed on the back surface side of a rotary atomization head 20, a pressure regulation chamber 30 provided with an exhaust channel 33 which is opened to an outer circumferential surface is formed between the nozzle insertion port 23 and a connection mechanism 22 and an outlet 34 of the exhaust channel 33 is opened and formed on such a position that a straight line distance from a rotation center C gets to larger than a radius of a part supported by a radial bearing 14 of the hollow rotation shaft 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coating machine in which a rotary atomizing head is attached to the tip of a hollow rotary shaft that is driven to rotate at high speed by an air motor built in a coating machine body, and a rotary atomizing head used in the coating machine.

  FIG. 4 shows a conventional general rotary atomizing type coating machine 40, in which a rotary atomizing head 50 is attached to the tip of a hollow rotary shaft 43 of an air motor 42 incorporated in a main body 41 of the coating machine. A feed tube 44 is inserted into the shaft 43.

  The air motor 42 is formed by integrally mounting an air turbine 46 on the rear end side of the hollow rotary shaft 43 supported by a radial bearing 45, and is rotated by compressed air blown from an air supply port 47 formed on the outer periphery of the turbine. The exhaust air is driven and discharged to the outside through the main exhaust passage 48 on the back side of the coating machine 40.

  The rotary atomizing head 50 has a cylindrical nut (cylinder) that is screwed to the bolt portion 43a of the hollow rotary shaft 43 on the back side thereof via a bell inner 51 that is disposed opposite to the tip opening of the feed tube 44. And a paint chamber 54 in which a nozzle insertion port 53 for inserting the tip of a feed tube 44 inserted into the hollow rotary shaft 43 is formed, and a substantially frustoconical surface is formed on the front side thereof. The rim 55 is formed.

  When the rotary atomizing head 50 is driven to rotate at high speed by the air motor 42 and a high voltage (−45 to 90 kV) of the negative electrode is applied and the paint is supplied through the feed tube 44, the paint dropped on the back side of the bell inner 51 The centrifugal force acts on the rim 55, flows out from the paint chamber 54 through the paint outflow hole 56 opened at the peripheral edge thereof, is spread on the rim 55, and is atomized at the tip.

In the coating machine 40, the paint or the like supplied from the feed tube 44 to the paint chamber 54 is positively applied to the hollow rotary shaft 43 so as not to flow into the gap between the hollow rotary shaft 43 and the feed tube 44 through the nozzle insertion port 53. When a part of the exhaust air flows into the hollow rotary shaft 43 when the air turbine 47 is rotated at a high speed, the pressure in the hollow rotary shaft 43 is increased. Along with this, if the pressure in the paint chamber 54 of the rotary atomizing head 50 in communication is too high, the atomization state of the paint is adversely affected.
For example, there is a problem that paint particles containing bubbles are blown out from the paint outflow hole 56 or paint is blown out without being atomized from the cleaning flow path 57 formed in the central portion of the bell inner 51, resulting in poor coating. there were.

Therefore, in order to relieve the pressure in the hollow rotary shaft 43, as shown in FIG. 4, a configuration in which an exhaust passage 58 is formed on the side surface of the nozzle insertion port 53 formed on the back side of the rotary atomizing head 50 is proposed. (See Patent Document 1).
However, according to experiments by the present inventors, it has been found that even if such an exhaust passage 58 is formed, the pressure in the paint chamber 54 may not be effectively reduced.

  Although the cause is unknown, since the gap between the nozzle insertion port 53 and the feed tube 44 is very narrow, the pressure in the hollow rotary shaft 43 increases, and air passes through the nozzle insertion port 53 to the paint chamber 54 side. When the flow velocity of the nozzle insertion port 53 increases, the exhaust passage 58 functions as an ejector, and it is conceivable that external air flows backward through the exhaust passage 58 and flows into the hollow rotary shaft 43.

  On the other hand, as shown in FIG. 5, there has also been proposed a structure in which an exhaust passage 59 that communicates the inside and the outside is formed on the side wall of a hollow rotating shaft 43 having a relatively wide passage (see Patent Document 2). 5 that are the same as those in FIG. 4 are given the same reference numerals, and detailed descriptions thereof are omitted.

According to this, since the space | interval of the hollow rotating shaft 43 and the feed tube 43 of the part in which the exhaust flow path 59 was formed is comparatively large, the exhaust flow path 59 does not function as an ejector.
However, it was found that even this could not secure a sufficient displacement.

Recently, in order to rotate the air motor 42 at a higher speed than ever before, or to prevent the rotational speed of the rotary atomizing head 50 from being reduced when painting with a large discharge amount, compression is blown to the air turbine 46. Air is supplied at a higher pressure and a larger flow rate.
In such a case, since the amount of air flowing into the hollow rotating shaft 43 increases, it is necessary to ensure a sufficient exhaust amount, but the exhaust amount depends on the centrifugal force acting on the exhaust passage 59, It is considered that sufficient centrifugal force does not act on the coating machine as shown in FIG.

Japanese Patent Laid-Open No. 09-220498 International Publication No. 2015/004966 Pamphlet

  In view of this, the present invention has a technical problem of allowing a sufficient centrifugal force to act on an exhaust passage communicating between the inside and the outside of a hollow rotating shaft so that air in the space can be quickly exhausted.

In order to solve this problem, the present invention is a hollow rotary shaft that is driven to rotate by an air motor built in the coating machine body, is supported by a radial bearing, and a rotary atomizing head is attached to the tip thereof.
The rotary atomizing head has a cylindrical coupling mechanism attached to and fixed to the hollow rotary shaft, a nozzle insertion port for inserting a tip of a feed tube inserted into the hollow rotary shaft, and the feed A paint chamber that receives the supply of paint from the tube is formed,
On the front side, in a coating machine in which a rim having a substantially frustoconical surface shape is formed, which spreads the paint that has flowed out from the paint chamber by centrifugal force and atomizes at the tip,
A pressure adjusting chamber through which the feed tube passes is formed between the nozzle insertion port of the rotating atomizing head and the coupling mechanism, and the pressure adjusting chamber is opened to the outer peripheral surface of the rotating atomizing head. An exhaust passage is formed,
The outlet of the exhaust passage is characterized in that an opening is formed at a position where the linear distance from the rotation center is larger than the radius of the portion of the hollow rotary shaft supported by the radial bearing.

According to the coating machine according to the present invention, the pressure adjusting chamber through which the feed tube passes is formed between the nozzle insertion port formed on the back side of the rotary atomizing head and the cylindrical coupling mechanism, and the pressure adjusting chamber Is formed with an exhaust passage open to the outer peripheral surface.
For example, the inner diameter of the pressure adjusting chamber is larger than the inner diameter of the nozzle insertion port and the inner diameter of the hollow rotary shaft, thereby forming orifices on the upstream side and the downstream side of the feed tube with the pressure adjusting chamber interposed therebetween. Therefore, once the air passing through the hollow rotating shaft toward the paint chamber is temporarily stored and the pressure in the pressure adjustment chamber becomes high, the internal air is discharged through the exhaust passage and the pressure is released.
At this time, the outlet of the exhaust passage is formed in an opening at a position where the linear distance from the rotation center is larger than the radius of the portion of the hollow rotary shaft supported by the radial bearing. The centrifugal force acting on the air is greater than the centrifugal force acting on the outer peripheral surface of the hollow rotary shaft, and therefore, sufficient exhaust volume is ensured as compared with the case where the exhaust passage is formed on the hollow rotary shaft. Can do.

Explanatory drawing which shows an example of the coating machine which concerns on this invention. The cross-sectional view of the rotary atomizing head according to the present invention. The longitudinal cross-sectional view of the rotary atomization head which concerns on this invention. Explanatory drawing which shows a conventional apparatus. Explanatory drawing which shows a conventional apparatus.

In the present invention, a hollow rotary shaft that is rotationally driven by an air motor built in the coating machine body is supported by a radial bearing, and a rotary atomizing head is attached to the tip thereof.
The rotary atomizing head has a cylindrical coupling mechanism attached to and fixed to the hollow rotary shaft, a nozzle insertion port for inserting a tip of a feed tube inserted into the hollow rotary shaft, and the feed A paint chamber that receives the supply of paint from the tube is formed,
On the front side, in a coating machine in which a rim having a substantially frustoconical surface shape is formed, which spreads the paint that has flowed out from the paint chamber by centrifugal force and atomizes at the tip,
A pressure adjusting chamber through which the feed tube passes is formed between the nozzle insertion port of the rotating atomizing head and the coupling mechanism, and the pressure adjusting chamber is opened to the outer peripheral surface of the rotating atomizing head. An exhaust passage is formed,
The outlet of the exhaust passage is characterized in that an opening is formed at a position where the linear distance from the rotation center is larger than the radius of the portion of the hollow rotary shaft supported by the radial bearing.

  FIG. 1 shows an example of a coating machine according to the present invention. The coating machine 1 has a rotary atomizing head 20 at the tip of a hollow rotary shaft 12 that is driven to rotate at high speed by an air motor 11 built in the coating machine body 10. The feed tube 13 is inserted into the hollow rotary shaft 12.

  The air motor 11 is formed by integrally mounting an air turbine 15 on the rear end side of the hollow rotary shaft 12 supported by a radial bearing 14, and is rotated by compressed air blown from an air supply port 16 formed on the outer periphery of the turbine. The exhaust air is driven and discharged to the outside through the main exhaust passage 17 on the back side of the coating machine 1.

  The rotary atomizing head 20 has a cylindrical nut (cylinder) screwed to the bolt portion 12a of the hollow rotary shaft 12 on the back side thereof via a bell inner 21 disposed opposite to the tip opening of the feed tube 13. Shaped coupling mechanism) 22, a nozzle insertion port 23 for inserting the tip of the feed tube 13 inserted into the hollow rotary shaft 12, and a paint chamber 24 for receiving paint supply from the feed tube 13 are formed on the front side thereof. The rim 25 having a substantially frustoconical surface is formed.

  A paint outflow hole 26 is formed in the peripheral portion of the bell inner 21 to allow the paint in the paint chamber 24 to flow out to the rim 25 side by centrifugal force when the rotary atomizing head 20 is rotated. A cleaning flow path 27 for cleaning the front side of the bell inner 21 by causing the cleaning liquid supplied into the paint chamber 24 to flow out during cleaning is formed.

A pressure adjusting chamber 30 through which the feed tube 13 passes is formed between the nozzle insertion port 23 of the rotary atomizing head 20 and the cylindrical nut 22.
The inner diameter of the pressure adjusting chamber 30 is larger than the inner diameter of the hollow rotary shaft 12 and the inner diameter of the nozzle insertion port 23, so that orifices are respectively provided on the upstream side and the downstream side of the feed tube 13 with the pressure adjusting chamber 26 interposed therebetween. 31 and 32 are formed.
The upstream orifice 31 is formed by a gap between the hollow rotary shaft 12 and the feed tube 13, and the downstream orifice 32 is formed by a gap between the nozzle insertion port 23 and the feed tube 13.

In addition, an exhaust passage 33 opened on the outer peripheral surface of the rotary atomizing head 20 is formed in the pressure adjusting chamber 30.
The outlet 34 of the exhaust passage 33 is formed at a position where the linear distance from the rotation center C is larger than the radius of the portion of the hollow rotary shaft 12 supported by the radial bearing 14.
That is, the opening position P34 of the outlet 34 is outside the outer peripheral surface position P12 corresponding to the radius of the hollow rotary shaft 12.
Further, the sum of the cross-sectional areas of the narrowest portions of the exhaust passages 33 is formed wider than the cross-sectional area of the downstream orifice 32, so that the air in the pressure adjustment chamber 30 can easily escape from the exhaust passage 33 to the outside. ing.
In addition, the outlet 34 of the exhaust passage 33 is opened to the rear side of the opening position of the shaping air outlets 18 and 19 so that the exhaust from the pressure adjusting chamber 30 does not adversely affect the air flow of the shaping air. Has been.

  The exhaust flow path 33 is not limited to being formed in a radial shape as shown in FIG. 2A, but is formed, for example, in the tangential direction of the annular peripheral wall of the pressure adjusting chamber 30 as shown in FIG. May be. Although it is preferable that the exhaust flow path 33 shown in FIG.2 (b) is opening backward with respect to the rotation direction, it is not restricted to this.

Further, as shown in FIG. 1, the exhaust passage 33 is not limited to being formed in a horizontal direction (a direction orthogonal to the rotation center C), and the exhaust passage 33 shown by a solid line in FIG. Thus, it may be formed to be inclined to the front side, or may be formed to be inclined to the back side as in the exhaust flow path 33 shown by a broken line in FIG.
Furthermore, as shown in FIG. 3B, the channel cross section may be substantially enlarged by branching in the middle.
The shape of the exhaust flow path 33 is not limited thereto, and may be, for example, a shape in which the flow path cross section is expanded stepwise or continuously from the pressure adjustment chamber 30 side toward the outlet 34.

The above is one configuration example of the present invention, and the operation thereof will be described next.
When the rotary atomizing head 20 was driven to rotate at high speed by the air motor 11 and a high voltage (−45 to 90 kV) of the negative electrode was applied and the paint was supplied through the feed tube 13, it was dropped on the back side of the bell inner 21. Centrifugal force acts on the paint, flows out from the paint chamber 24 through the paint outflow hole 26 opened at the peripheral edge thereof, spreads on the rim 25, and is atomized at the tip.

At this time, when a part of the exhaust of the air motor 11 flows into the hollow rotary shaft 12 from the rear end opening, the air flows down toward the rotary atomizing head 20, passes through the orifice 31 on the upstream side, and pressure It flows into the adjustment chamber 30.
Since the pressure adjustment chamber 30 functions as a buffer, even if the internal pressure fluctuates due to air flowing into the pressure adjustment chamber 30, the change is not directly reflected as the pressure fluctuation in the paint chamber 24.

Further, since the exhaust flow path 33 is formed in the pressure adjustment chamber 30, when the pressure in the pressure adjustment chamber 30 becomes high, the exhaust is passed through the exhaust flow path 33.
At this time, the outlet 34 of the exhaust passage 33 is formed at a position where the linear distance from the rotation center C is larger than the radius of the portion of the hollow rotary shaft 12 supported by the radial bearing 14. Even if the rotational speed is constant, a larger centrifugal force acts than when the exhaust passage is formed in the hollow rotary shaft 12 or the cylindrical nut 22.
As a result, the amount of exhaust discharged outside through the exhaust passage 33 increases, so that smooth exhaust can be performed.

  Even if a sudden pressure increase occurs in the pressure adjusting chamber 30 for some reason, the cross-sectional area of the exhaust passage 33 is larger than that of the downstream orifice 32, so that the paint passes through the downstream orifice 32. The flow of air toward the chamber 24 is blocked, and the air in the pressure adjustment chamber 30 is reliably discharged outside through the exhaust passage 33.

  As described above, according to the present invention, the change in the pressure adjusting chamber 30 does not directly affect the pressure in the paint chamber 24, so that the coating failure is less likely to occur, and the exhaust gas formed in the pressure adjusting chamber 30 is not affected. The outlet 34 of the flow path 33 is opened at a position where the linear distance from the rotation center C is larger than the radius from the rotation center C to the outer peripheral surface of the hollow rotation shaft 12. Compared with the case where the exhaust passage is formed in the 12 or the cylindrical nut 22, a large centrifugal force can be applied to ensure a sufficient exhaust amount.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a coating machine provided with a rotary atomizing head that is rotationally driven by an air motor built in the coating machine body, and a rotary atomizing head used therefor.

DESCRIPTION OF SYMBOLS 1 Coating machine 10 Coating machine main body 11 Air motor 12 Hollow rotating shaft 13 Feed tube 14 Radial bearing 15 Air turbine 16 Supply port 17 Main exhaust flow path 20 Rotating atomizing head 21 Bell inner 22 Cylindrical nut (cylindrical coupling mechanism)
23 Nozzle insertion port 24 Paint chamber 25 Rim 30 Pressure adjustment chamber 33 Exhaust flow path 34 Outlet C Rotation center

Claims (7)

A hollow rotating shaft that is driven to rotate by an air motor built into the main body of the coating machine is supported by a radial bearing, and a rotary atomizing head is attached to its tip.
The rotary atomizing head has a cylindrical coupling mechanism attached to and fixed to the hollow rotary shaft, a nozzle insertion port for inserting a tip of a feed tube inserted into the hollow rotary shaft, and the feed A paint chamber that receives the supply of paint from the tube is formed,
On the front side, in a coating machine in which a rim having a substantially frustoconical surface shape is formed, which spreads the paint that has flowed out from the paint chamber by centrifugal force and atomizes at the tip,
A pressure adjusting chamber through which the feed tube passes is formed between the nozzle insertion port of the rotating atomizing head and the coupling mechanism, and the pressure adjusting chamber is opened to the outer peripheral surface of the rotating atomizing head. An exhaust passage is formed,
The exhaust port of the exhaust passage is formed with an opening at a position where a linear distance from the rotation center is larger than a radius of a portion of the hollow rotation shaft supported by the radial bearing.   2. The coating machine according to claim 1, wherein the exhaust passage is formed in a shape in which a cross section of the passage gradually or continuously expands from the pressure regulation chamber side toward the outlet.   The coating machine according to claim 1 or 2, wherein an inner diameter of the pressure adjusting chamber is formed larger than an inner diameter of a nozzle insertion port and an inner diameter of a tip end of a hollow rotary shaft.   An orifice is formed on each of the upstream and downstream sides of the feed tube across the pressure adjusting chamber, the upstream orifice is formed by a gap between the hollow rotating shaft and the feed tube, and the downstream orifice is the nozzle insertion port and the feed tube. The coating machine according to claim 3, wherein the coating machine is formed by a gap of   The coating machine according to claim 4, wherein the sum of the cross-sectional areas of the narrowest portion of the exhaust passage is formed wider than the cross-sectional area of the downstream orifice. It is attached to the tip of a hollow rotating shaft that is driven to rotate by an air motor built in the coating machine body,
A cylindrical coupling mechanism attached and fixed to the hollow rotary shaft, a nozzle insertion port for inserting a tip of a feed tube inserted into the hollow rotary shaft, and a paint chamber for receiving paint supply from the feed tube Formed into
In the rotary atomizing head in which a substantially frustoconical rim that spreads the paint that has flowed out from the paint chamber by centrifugal force and atomizes at the tip thereof is formed on the front side,
Between the nozzle insertion port and the coupling mechanism, a pressure adjustment chamber through which the feed tube passes is formed, and an exhaust passage opened to the outer peripheral surface is formed in the pressure adjustment chamber,
The outlet of the exhaust passage has an opening formed at a position where the linear distance from the rotation center is larger than the radius of the portion of the hollow rotary shaft supported by the radial bearing. . The rotary atomizing head according to claim 6, wherein the exhaust passage is formed in a shape in which a cross section of the passage expands stepwise or continuously from the pressure regulation chamber side toward the outlet.

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