JP6525318B2 - Painting machine and rotary atomizing head used therefor - Google Patents

Description

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

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

  The air motor 42 has an air turbine 46 integrally attached to the rear end side of the hollow rotating shaft 43 supported by the radial bearing 45, and is rotated by compressed air blown from the air supply port 47 formed on the turbine outer periphery. The air is driven, and the exhaust air is discharged to the outside through the main exhaust flow path 48 on the back side of the coater 40.

  The rotary atomizing head 50 is a cylindrical nut (cylinder) screwed to the bolt portion 43 a of the hollow rotary shaft 43 on the back side through the bell inner 51 disposed opposite to the tip opening of the feed tube 44. Paint chamber 54 in which a nozzle insertion port 53 for inserting the tip of the feed tube 44 inserted into the hollow rotary shaft 43 is formed, and a substantially frusto-conical surface is formed on the front side Rim 55 is formed.

  When high voltage (-45 to 90 kV) of the negative electrode is applied while the rotary atomizing head 50 is rotationally driven at high speed by the air motor 42 and the paint is supplied through the feed tube 44, the paint dropped to the back side of the bell inner 51 Centrifugal force acts on the surface, and the paint chamber 54 flows out from the paint chamber 54 through the paint outlet hole 56 opened at the peripheral edge, spreads on the rim 55, and is atomized at its tip.

In this coating machine 40, the hollow rotary shaft 43 is actively driven so that the paint or the like supplied from the feed tube 44 to the paint chamber 54 does not flow into the gap between the hollow rotary shaft 43 and the feed tube 44 through the nozzle insertion port 53. When the air turbine 47 is rotated at a high speed, or when a portion of the exhaust air flows into the hollow rotary shaft 43, the pressure in the hollow rotary shaft 43 becomes high. At the same time, if the pressure in the paint chamber 54 of the communicating rotary atomizing head 50 becomes too high, the atomization state of the paint is adversely affected.
For example, paint particles containing air bubbles are blown out from the paint outflow hole 56, or the paint is sprayed from the cleaning flow path 57 formed in the central portion of the bell inner 51 without being finely divided to cause a coating failure. there were.

Therefore, in order to release the pressure in the hollow rotary shaft 43, as shown in FIG. 4, one in which the exhaust flow path 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 the experiments of the present inventors, it has been found that even if such an exhaust flow 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 becomes high, and air passes through the nozzle insertion port 53 to the paint chamber 54 side. When the flow rate of the nozzle insertion port 53 increases when it flows, the exhaust flow passage 58 functions as an ejector, and it is conceivable that external air flows back into the exhaust flow passage 58 and flows into the hollow rotary shaft 43.

  On the other hand, as shown in FIG. 5, an exhaust flow passage 59 communicating the inside and the outside is formed on the side wall of a relatively wide hollow rotary shaft 43 of the flow passage has also been proposed (see Patent Document 2). In FIG. 5, the same parts as those in FIG. 4 are given the same reference numerals, and the detailed description will be omitted.

According to this, since the distance between the hollow rotary shaft 43 and the feed tube 43 in the portion where the exhaust flow passage 59 is formed is relatively large, the exhaust flow passage 59 does not function as an ejector.
However, it turned out that this can not secure a sufficient exhaust volume.

Particularly recently, in order to rotate the air motor 42 at a higher speed than ever or to prevent the rotational speed of the rotary atomizing head 50 from decreasing when painting with a large discharge amount, the compression sprayed on the air turbine 46 Air is supplied at higher pressure and higher flow rate.
In such a case, since the amount of air flowing into the hollow rotary shaft 43 is increased, it is necessary to secure 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 in the coating machine as shown in FIG.

Unexamined-Japanese-Patent No. 09-220498 gazette International Publication No. 2015/004966 brochure

  Therefore, the present invention has a technical object to make it possible to quickly exhaust the air in the space by causing a sufficient centrifugal force to act on the exhaust flow path communicating the inside and the outside of the hollow rotary shaft.

In order to solve this problem, according to the present invention, a hollow rotary shaft rotationally driven by an air motor incorporated in a body of a coating machine is supported by a radial bearing, and a rotary atomizing head is attached to the tip thereof
The rotary atomizing head has, on its back side, a cylindrical connecting mechanism attached and fixed to the hollow rotary shaft, a nozzle insertion port for inserting the tip of a feed tube inserted into the hollow rotary shaft, and the feed A paint chamber is formed to receive the supply of paint from the tube.
In the coating machine, a substantially frusto-conical surface-like rim is formed on the front side of the paint chamber, which spreads the paint flowed out from the paint chamber by centrifugal force and atomizes the paint at its tip,
A pressure control chamber through which the feed tube passes is formed between the nozzle insertion opening of the rotary atomizing head and the connection mechanism, and the pressure control chamber is open to the outer peripheral surface of the rotary atomizing head. An exhaust flow path is formed,
The outlet of the exhaust channel is characterized in that the linear distance from the center of rotation is formed to be larger than the radius of the portion supported by the radial bearing of the hollow rotary shaft.

According to the coating machine of the present invention, a pressure adjustment chamber through which the feed tube penetrates is formed between the nozzle insertion port formed on the back side of the rotary atomizing head and the cylindrical connection mechanism, and the pressure adjustment chamber is formed An exhaust flow path is formed on the outer peripheral surface.
For example, the inner diameter of the pressure adjustment chamber is formed larger than the inner diameter of the nozzle insertion port and the inner diameter of the hollow rotary shaft, whereby orifices are formed on the upstream and downstream sides of the feed tube across the pressure adjustment chamber. Therefore, the air passing through the hollow rotary shaft to the paint chamber is once stored, and when the pressure in the pressure control chamber becomes high, the internal air is discharged through the exhaust flow path to release the pressure.
At this time, the outlet of the exhaust flow passage is opened at a position where the linear distance from the rotation center is larger than the radius of the portion supported by the radial bearing of the hollow rotating shaft, so The centrifugal force acting on the air is larger than the centrifugal force acting on the outer peripheral surface of the hollow rotary shaft, and therefore, a sufficient displacement is secured as compared with the case where the exhaust flow path is formed on the hollow rotary shaft. Can.

Explanatory drawing which shows an example of the coating machine which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of a rotary atomizing head according to the present invention. FIG. 1 is a longitudinal sectional view of a rotary atomizing head according to the present invention. Explanatory drawing which shows a conventional apparatus. Explanatory drawing which shows a conventional apparatus.

According to the present invention, a hollow rotary shaft rotationally driven by an air motor incorporated in the body of the coating machine is supported by a radial bearing, and a rotary atomizing head is attached to the tip of the hollow rotary shaft.
The rotary atomizing head has, on its back side, a cylindrical connecting mechanism attached and fixed to the hollow rotary shaft, a nozzle insertion port for inserting the tip of a feed tube inserted into the hollow rotary shaft, and the feed A paint chamber is formed to receive the supply of paint from the tube.
In the coating machine, a substantially frusto-conical surface-like rim is formed on the front side of the paint chamber, which spreads the paint flowed out from the paint chamber by centrifugal force and atomizes the paint at its tip,
A pressure control chamber through which the feed tube passes is formed between the nozzle insertion opening of the rotary atomizing head and the connection mechanism, and the pressure control chamber is open to the outer peripheral surface of the rotary atomizing head. An exhaust flow path is formed,
The outlet of the exhaust channel is characterized in that the linear distance from the center of rotation is formed to be larger than the radius of the portion supported by the radial bearing of the hollow rotary shaft.

  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 which is driven to rotate at high speed by an air motor 11 built in the main body 10 of the coater. It is attached and the feed tube 13 is inserted into the hollow rotary shaft 12.

  The air motor 11 has an air turbine 15 integrally attached to the rear end side of the hollow rotary shaft 12 supported by the 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 air is driven, and the exhaust air is discharged to the outside through the main exhaust flow path 17 on the back side of the coater 1.

  The rotary atomizing head 20 is a cylindrical nut (cylinder) screwed to the bolt portion 12 a of the hollow rotary shaft 12 on the back side through the bell inner 21 disposed opposite to the tip opening of the feed tube 13. Connection 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 the supply of paint from the feed tube 13 are formed on the front side A rim 25 having a substantially frusto-conical surface is formed.

  At the periphery of the bell inner 21 is formed a paint outflow hole 26 for letting the paint in the paint chamber 24 flow out to the rim 25 side by centrifugal force when the rotary atomizing head 20 is rotated, and at the center part A cleaning flow channel 27 is formed which allows the cleaning liquid supplied into the paint chamber 24 to flow out during cleaning to clean the front side of the bell inner 21.

Further, a pressure adjustment 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 adjustment chamber 30 is formed larger than the inner diameter of the hollow rotary shaft 12 and the inner diameter of the nozzle insertion port 23, and thereby the orifices respectively upstream and downstream of the feed tube 13 with the pressure adjustment chamber 26 interposed therebetween. 31, 32 are formed.
The upstream orifice 31 is formed by the gap between the hollow rotary shaft 12 and the feed tube 13, and the downstream orifice 32 is formed by the gap between the nozzle insertion port 23 and the feed tube 13.

Further, in the pressure adjustment chamber 30, an exhaust flow path 33 opened to the outer peripheral surface of the rotary atomizing head 20 is formed.
The outlet 34 of the exhaust flow 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 outflow port 34 is outside the outer circumferential surface position P12 corresponding to the radius of the hollow rotary shaft 12.
In addition, the sum of the cross-sectional areas of the narrowest portions of the respective exhaust flow channels 33 is formed wider than the cross-sectional area of the orifice 32 on the downstream side, and the air in the pressure adjustment chamber 30 easily escapes from the exhaust flow channels 33 to the outside. ing.
In addition, the outlet 34 of the exhaust flow path 33 is opened on the back side of the opening position of the shaping air outlets 18 and 19 so that the exhaust from the pressure adjustment chamber 30 does not adversely affect the air flow of the shaping air. It is done.

  The exhaust flow path 33 is not limited to the case where the exhaust flow path 33 is formed radially as shown in FIG. 2A, for example, formed in the tangential direction of the annular peripheral wall of the pressure adjustment chamber 30 as shown in FIG. It may be done. Although it is preferable that the exhaust flow path 33 shown in FIG. 2B is opened backward with respect to the rotational direction, it is not limited thereto.

Furthermore, as shown in FIG. 1, the exhaust flow passage 33 is not limited to the case where it is formed in the horizontal direction (direction orthogonal to the rotation center C), and the exhaust flow passage 33 shown by a solid line in FIG. As in the case of FIG. 1, the front side may be formed to be inclined, and as shown in the broken line in the figure, it may be formed to be inclined to the rear side.
Furthermore, as shown in FIG. 3 (b), the flow path cross section may be substantially enlarged by branching on the way.
The shape of the exhaust flow passage 33 is not limited to these, and may be, for example, a shape such that the flow passage cross-section is gradually or continuously enlarged from the pressure adjustment chamber 30 side toward the outlet 34.

The above is one structural example of this invention, and the effect | action is demonstrated next.
The high voltage (-45 to 90 kV) of the negative electrode is applied while the rotary atomizing head 20 is driven to rotate at high speed by the air motor 11, and the paint is supplied through the feed tube 13. Centrifugal force acts on the paint, and it flows out of the paint chamber 24 through the paint outlet holes 26 opened at its peripheral edge, spreads on the rim 25, and is atomized at its tip.

At this time, when 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 and passes through the orifice 31 on the upstream side and the pressure It flows into the adjustment room 30.
Since the pressure control chamber 30 functions as a buffer, even if the pressure inside the pressure control chamber 30 fluctuates due to the air flowing into the pressure control chamber 30, the change is not directly reflected as a pressure fluctuation in the paint chamber 24.

Further, since the exhaust flow passage 33 is formed in the pressure adjustment chamber 30, when the pressure of the pressure adjustment chamber 30 becomes high, the exhaust flow passage 33 is exhausted through the exhaust flow passage 33.
At this time, the outlet 34 of the exhaust flow passage 33 is opened 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 large centrifugal force acts on the hollow rotary shaft 12 or the cylindrical nut 22 as compared with the case where the exhaust flow path is formed.
As a result, the amount of exhaust gas discharged to the outside through the exhaust flow path 33 is increased, so that smooth exhaust can be performed.

  Further, even if the pressure adjustment chamber 30 is suddenly increased in pressure by some factor, the cross-sectional area of the exhaust flow passage 33 is wider than the orifice 32 on the downstream side. The flow of air toward the chamber 24 is blocked, and the air in the pressure control chamber 30 is reliably discharged to the outside through the exhaust passage 33.

  As described above, according to the present invention, since the change in the pressure control chamber 30 does not directly affect the pressure in the paint chamber 24, the paint failure is less likely to occur, and furthermore, the exhaust formed in the pressure control chamber 30. Since the outlet 34 of the flow path 33 is formed 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, the hollow rotation shaft Compared with the case where the exhaust flow path is formed on the cylindrical nut 22 or the cylindrical nut 22, a large centrifugal force can be applied to ensure a sufficient exhaust amount.

  The present invention can be applied to a coating machine provided with a rotary atomizing head which is rotationally driven by an air motor incorporated in the body of the coating machine and a rotary atomizing head used therefor.

DESCRIPTION OF SYMBOLS 1 painting machine 10 painting machine main body 11 air motor 12 hollow rotating shaft 13 feed tube 14 radial bearing 15 air turbine 16 air supply port 17 main exhaust flow path 20 rotary atomizing head 21 bell inner 22 cylindrical nut (cylindrical connection 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 rotary shaft (12) , which is rotationally driven by an air motor (11) built in the sprayer main body (10) , is supported by a radial bearing (14) , and a rotary atomizing head (20) is attached at its tip ,
The rotary atomizing head has a cylindrical connection mechanism (22) attached and fixed to the hollow rotary shaft and a nozzle for inserting the tip of the feed tube (13) inserted into the hollow rotary shaft on the back side. An insertion port (23) and a paint chamber (24) for receiving the supply of paint from the feed tube are formed.
In the coating machine (1) , on the front side, a substantially frusto-conical rim (25) is formed which spreads the paint flowed out from the paint chamber by centrifugal force and atomizes it at its tip,
A pressure control chamber (30) through which the feed tube passes is formed between the nozzle insertion port of the rotary atomizing head and the connection mechanism, and the pressure control chamber has an outer peripheral surface of the rotary atomizing head. An open exhaust channel (33) is formed,
The outlet of the exhaust channel has a linear distance (C to P34) from the center of rotation that is larger than the radius (C to P12) of the portion where the hollow rotary shaft is supported in contact with the radial bearing in the axial direction. A sprayer characterized in that the opening is formed at a position.   The coating machine according to claim 1, wherein the exhaust flow path is formed in a shape in which the cross section of the flow path gradually or continuously expands from the pressure control chamber side toward the outlet.   The coating machine according to claim 1 or 2, wherein an inner diameter of the pressure adjustment chamber is formed larger than an inner diameter of the nozzle insertion port and a tip inner diameter of the hollow rotary shaft. An orifice (31, 32) is formed on the upstream side and the downstream side of the feed tube with the pressure adjustment chamber interposed therebetween, and the orifice (31) on the upstream side is formed by a gap between the hollow rotary shaft and the feed tube The coating machine according to claim 3, wherein the orifice (32) is formed by a gap between the nozzle insertion port and the feed tube.   The coating machine according to claim 4, wherein the sum of the cross-sectional areas of the narrowest part of the exhaust flow passage is formed wider than the cross-sectional area of the downstream orifice. In the painting machine (1),
Attached to the tip of the hollow rotary shaft (12) , which is rotationally driven by an air motor (11) built into the sprayer body (10) ,
A cylindrical connection mechanism (22) attached and fixed to the hollow rotary shaft, a nozzle insertion port (23) for inserting the tip of the feed tube (13) inserted into the hollow rotary shaft, and paint from the feed tube The paint room (24) that receives the supply of
A rotary atomizing head (20) having a substantially frusto-conical rim (25) formed on the front side for spreading the paint flowed out from the paint chamber by centrifugal force and atomizing it at its tip; ,
A pressure control chamber (30) through which the feed tube passes is formed between the nozzle insertion port and the connection mechanism, and an exhaust flow path (33) opened on the outer peripheral surface is formed in the pressure control chamber. Equipped with a rotating atomizing head,
The outlet of the exhaust flow path has a linear distance (C to P34) from the rotation center larger than the radius (C to P12) of the portion where the hollow rotary shaft is supported in contact with the radial bearing in the axial direction A sprayer characterized in that the opening is formed at a position. The coating machine according to claim 6, wherein the exhaust flow passage is formed in a shape in which the flow passage cross-section gradually or continuously expands from the pressure control chamber side toward the outlet.

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