JP2005058802A - Coating gun - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating gun capable of preventing the intrusion of liquid supplied to a storage chamber of a rotary atomizing head into the back side of the inner part of a body. <P>SOLUTION: A discharge path 37 which is communicated with an annular clearance 27, is opened outside the body 10 and is nearly radial is disposed on the back side from the annular clearance 27 between the outer periphery of a passage pipe 12 and the inner periphery of a center hole 26 of the rotary atomizing head 11. The liquid passes through the annular clearance 27 from the storage chamber 17 of the rotary atomizing head 11, advances to the discharge path 37 thereon, is imparted with a centrifugal force through the rotation of the rotary atomizing head 11 and is discharged outside the body 10 by the centrifugal force. As a result, there is no fear that the liquid is intruded into the interior of the back side in the inner part of the body 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating gun having a rotary atomizing head.
[0002]
[Prior art]
A coating gun with a rotary atomizing head at the tip has a cup-shaped rotation that is fixed to the center of the body and serves as a flow path for paint and thinner. The structure supports the atomizing head. The front end of the flow channel pipe passes through the central hole of the rotary atomizing head and faces a storage chamber provided in the rotary atomizing head. The paint or thinner supplied from the flow pipe to the storage chamber passes through a small hole in the front wall of the storage chamber, and is sent to the tapered surface of the rotary atomizing head. It spreads radially to the side and is emitted in an atomized form from the outer periphery. In addition, there exists a thing currently disclosed by patent document 1 as a coating gun provided with a rotary atomization head.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-216567
[Problems to be solved by the invention]
In the case of the coating gun as described above, since the rotary atomizing head rotates at a high speed, a seal member cannot be interposed between the outer periphery of the front end portion of the flow path tube and the inner periphery of the center hole. Therefore, as shown in FIG. 8, an annular gap 102 is slightly formed between the outer periphery of the front end portion of the flow channel tube 100 and the inner periphery of the center hole 101. When such an annular gap 102 is vacant, the paint or thinner fed into the storage chamber 103 passes through the annular gap 102 and follows the outer periphery of the flow channel pipe 100 as shown by the arrow in FIG. There is a risk that the inside of 104 may invade backward. In particular, when a large amount of thinner is flowed in order to increase the cleaning efficiency, the interior of the storage chamber 103 is filled with thinner and overflows, so that the intrusion to the rear is remarkable.
[0005]
The present invention has been made in view of the above circumstances, and aims to prevent the liquid supplied to the storage chamber of the rotary atomizing head from entering the rear of the body.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, a flow path pipe is fixed in the body, and a cup-shaped rotary atomizing head that is rotationally driven concentrically with the flow path pipe is provided at the front end of the body. The front end portion penetrates the central hole of the rotary atomizing head and faces the storage chamber in the rotary atomizing head, and the liquid supplied from the flow channel pipe to the storage chamber is the front wall of the storage chamber In the coating gun which passes along the tapered surface of the rotary atomizing head by centrifugal force and is discharged in an atomized form from the outer periphery thereof, the outer periphery of the flow path tube and the center hole A liquid that is located behind the annular gap between the inner circumference and communicates with the annular gap and that is open to the outside of the body and has a generally radial discharge path, and enters the discharge path. In the configuration, centrifugal force is applied by the rotation of the rotary atomizing head.
[0007]
According to a second aspect of the present invention, in the first aspect of the invention, air is supplied toward the discharge path side in a space communicating with the discharge path and extending rearward along the outer periphery of the flow path pipe. It was.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the cross-sectional area perpendicular to the flow path pipe is larger than the cross-sectional area of the annular gap in the communicating portion of the discharge passage with the annular gap. A large decompression chamber was provided.
[0008]
According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the liquid in the discharge path flows in the circumferential direction in the discharge path by rotating integrally with the rotary atomizing head. It was set as the structure provided with the fin to be made.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the opening to the outside of the body in the discharge passage is opposite to the tapered surface at the outer peripheral edge of the rotary atomizing head. It was set as the structure which faces the outer peripheral surface.
[0009]
[Action and effect of the invention]
[Invention of Claim 1]
Even if the liquid supplied to the storage chamber passes through the annular gap between the outer periphery of the flow channel tube and the inner periphery of the center hole and enters the discharge path, the liquid is discharged out of the body by centrifugal force. Therefore, there is no possibility that the liquid may penetrate into the back of the body.
[Invention of claim 2]
By the pressure of air, the penetration | invasion to the back of a liquid is suppressed or prevented more reliably. Further, when the air flows out to the outer periphery of the body through the discharge path, the liquid in the discharge path is reliably discharged out of the body by multiplying the outflow air.
[0010]
[Invention of claim 3]
The liquid that has passed through the annular gap while being pressurized by filling the storage chamber is decompressed as it flows into the decompression chamber due to the difference in cross-sectional area between the decompression chamber and the annular gap. Therefore, intrusion into the rear of the body is suppressed or reliably prevented.
[Invention of claim 4]
Since the liquid in the discharge path is caused to flow in the substantially circumferential direction by the fins, the accumulated centrifugal force is increased, and the discharge efficiency to the outside of the body is improved.
[0011]
[Invention of claim 5]
The paint adhering to the outer peripheral surface opposite to the tapered surface at the outer peripheral edge of the rotary atomizing head can be cleaned by the thinner discharged from the discharge passage.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
The coating gun of this embodiment is provided with a rotary atomizing head 11 at the front end portion (left end portion in FIG. 1) of the body 10. Inside the body 10, a slender channel pipe 12 having a cylindrical shape with an axis line directed in the front-rear direction is fixed. The inner diameter of the channel tube 12 is constant over the entire length, but the outer diameter is reduced concentrically and stepwise only at the front end, and the front end with the reduced outer diameter is the reduced diameter portion 13 and It has become. A paint supply source (not shown) and a thinner supply source (not shown) provided outside the coating gun are connected to the rear end portion of the flow path pipe 12 when painting. The liquid paint P is supplied from the paint supply source to the flow path pipe 12, and the thinner T for cleaning is supplied from the thinner supply source to the flow path pipe 12 at the time of changeover after painting or color change. It has become.
[0013]
In addition, an annular space 16 is formed between the body 10 and the outer peripheral surface of the flow channel tube 12, and a rotating shaft 14 having a cylindrical shape concentric with the flow channel tube 12 is rotatably supported. The rotary shaft 14 is driven to rotate at high speed by blowing turbine air At to the turbine blades 15 provided on the outer periphery thereof. Further, a part of the turbine air At advances forward in the annular space 16 between the outer periphery of the flow channel tube 12 and the inner periphery of the rotary shaft 14.
[0014]
A rotary atomizing head 11 having a cup shape (dish shape) opened forward is attached to a front end portion of the rotary shaft 14 so as to rotate integrally with the rotary shaft 14. A flat storage chamber 17 that is concentric with the rotary atomizing head 11 and has a small size in the front-rear direction is formed inside the rotary atomizing head 11. A projection 19 is formed at the central position of the front wall 18 of the storage chamber 17 in a substantially conical shape to the rear, and the peripheral portion of the rear wall 20 of the storage chamber 17 is curved forward to the periphery of the front wall 18. Thus, a guide surface 21 that is continuous with an acute angle is formed.
[0015]
A concentric circular dish-shaped recess 22 is formed on the front surface of the rotary atomizing head 11, and the inner periphery of the recess 22 is a tapered surface 23 whose diameter increases toward the front. The front wall 18 of the storage chamber 17 is a partition that partitions the storage chamber 17 and the recess 22. A plurality of small holes 24 penetrating from the peripheral edge of the storage chamber 17 to the tapered surface 23 are formed in the front wall 18 at intervals in the circumferential direction. The small hole 24 penetrates in the direction along the guide surface 21 of the rear wall 20 of the storage chamber 17. In the protrusion 19, a small-diameter communication hole 25 that opens from the storage chamber 17 to the center of the recess 22 is also formed.
[0016]
A central hole 26 having a circular shape concentric with the rotary atomizing head 11 and having an inner diameter slightly larger than the outer diameter of the reduced diameter portion 13 of the flow path tube 12 penetrates the rear wall 20 of the storage chamber 17 in the front-rear direction. Is formed. The reduced diameter portion 13 passes through the center hole 26, and the front end portion of the reduced diameter portion 13 faces the storage chamber 17 and concentrically faces the protrusion 19. The outer periphery of the reduced diameter portion 13 and the inner periphery of the center hole 26 are kept in a non-contact state, so that the rotary atomizing head 11 and the rotary shaft 14 can smoothly rotate at high speed. An annular gap 27 is formed between the outer periphery of the reduced diameter portion 13 and the inner periphery of the center hole 26 and forms an annular shape and communicates between the storage chamber 17 and the annular space 16.
[0017]
When the liquid paint P is supplied to the flow path pipe 12 with the rotary atomizing head 11 rotated at a high speed, the liquid paint P is dropped into the storage chamber 17 from the front end of the flow path pipe 12, and FIGS. As shown in FIG. 2, the centrifugal force moves to the peripheral portion of the storage chamber 17, passes through the small hole 24, is sent to the tapered surface 23, and is also diffused in the circumferential direction while moving forward through the tapered surface 23 by centrifugal force. From the outer peripheral edge of the taper surface 23 (rotating atomizing head 11), it is atomized and discharged radially. A part of the liquid paint P supplied to the storage chamber 17 is fed into the recess 22 through the communication hole 25 of the protrusion 19 and moves to the tapered surface 23 by centrifugal force.
[0018]
Further, at the end of painting or at the time of setup change such as color change, the thinner T is supplied to the flow path pipe 12 for cleaning. However, in order to improve the cleaning efficiency, the supply amount of the thinner T is the paint P It is larger than the supply amount. Accordingly, the thinner T that has flowed into the storage chamber 17 from the front end of the flow path pipe 12 fills the storage chamber 17 and passes through the small hole 24 and the communication hole 25 in a pressurized state, as shown in FIG. It reaches the recess 22, flows on the tapered surface 23 by centrifugal force, and is discharged from the outer periphery. In this way, the passage route of the thinner T is cleaned.
[0019]
In addition, a substantially front half region from the front end (outer peripheral edge of the tapered surface 23) to the substantially center position in the front-rear direction of the outer periphery of the rotary atomizing head 11 is a tapered outer peripheral surface 28 that is gradually reduced in diameter toward the rear. The substantially second half region of the outer periphery of the rotary atomizing head 11 is a constant-diameter outer peripheral surface 29 having a constant outer diameter. The outer diameter of the constant-diameter outer peripheral surface 29 is the same as the outer diameter of the rear end of the tapered outer peripheral surface 28 (the minimum outer diameter of the tapered outer peripheral surface 28). The surface 29 continues without a step.
[0020]
Further, a cover 30 having a cup shape concentric with the rotary atomizing head 11 is fixed to the rotary atomizing head 11 so as to be integrally rotatable. A substantially first half portion of the inner periphery of the cover 30 has a tapered inner periphery whose diameter is slightly larger than that of the tapered outer peripheral surface 28 of the rotary atomizing head 11 and whose taper gradient is the same angle as the tapered outer peripheral surface 28. A circular tapered channel 32 that is continuous over the entire circumference is formed between the tapered inner peripheral surface 31 and the tapered outer peripheral surface 28. The tapered channel 32 constitutes a discharge channel 37 which will be described later. A constant-diameter inner peripheral surface 33 that is larger than the outer diameter of the constant-diameter outer peripheral surface 29 of the rotary atomizing head 11 and that is continuous with the rear end of the tapered inner peripheral surface 31 is formed on the inner periphery of the cover 30. Has been. Between the constant-diameter inner peripheral surface 33 and the constant-diameter outer peripheral surface 29, an annular annular channel 34 that is continuous over the entire circumference is formed. This annular flow path 34 also constitutes a discharge path 37. The cover 30 is fixed to the rotary atomizing head 11 in such a form that its inner peripheral rear end is in close contact with the rear end of the constant diameter outer peripheral surface 29 of the rotary atomizing head 11.
[0021]
At the front end portion of the body 10, a jet port 35 having a diameter larger than the outermost diameter of the rotary atomizing head 11 and forming a circular slit shape between them is an outer peripheral edge of the tapered surface 23 (front end of the rotary atomizing head 11). It is formed to be located rearward. The ejection port 35 communicates with a supply path 36 in the body 10, and an air supply source (not shown) is connected to the rear end of the supply path 36. The air pressure-fed from the air supply source is ejected forward as the shaping air As from the ejection port 35 toward the outer peripheral edge of the rotary atomizing head 11 and discharged from the outer peripheral edge of the rotary atomizing head 11 (tapered surface 23). The atomized paint P thus formed is shaped into a predetermined pattern while being squeezed toward the center by blowing the shaping air As.
[0022]
Now, in the case of the structure in which the annular gap 27 is vacant between the flow channel pipe 12 and the center hole 26 as described above, the paint P and the thinner T fed into the storage chamber 17 pass through the annular gap 27 and flow. There is a concern that the inside of the annular space 16 may enter the rear side of the body 10 (to the right in FIGS. 1 to 5) along the outer periphery of the road pipe 12. Therefore, as a countermeasure, in the present embodiment, there is provided a discharge path 37 having a generally radial shape that is located behind the annular gap 27, communicates with the annular gap 27, and is open to the outside of the body 10. .
[0023]
The discharge path 37 includes a decompression chamber 38, a radiation hole 39, an annular flow path 34, and a tapered flow path 32 arranged in order from the center side toward the outer peripheral side.
The decompression chamber 38 has a circular shape concentric with the annular gap 27 and is continuous over the entire circumference, and its central portion communicates with the rear end of the annular gap 27. Since the inner diameter of the decompression chamber 38 is larger than the inner diameter of the annular gap 27, the cross-sectional area of the decompression chamber 38, that is, the cross-sectional area perpendicular to the axial direction (front-rear direction) of the flow path pipe 12 is the transverse area of the annular gap 27. Big enough than. The decompression chamber 38 communicates with the front end of the annular space 16 between the outer periphery of the flow channel tube 12 and the inner periphery of the rotating shaft 14. Therefore, the turbine air At sent into the annular space 16 flows into the decompression chamber 38.
[0024]
The radiation holes 39 are elongate circular holes that extend straight outward from the inner peripheral surface of the decompression chamber 38 in the radial direction, and a plurality of the radiation holes 39 are formed at equal angular intervals (60 ° in the present embodiment) in the circumferential direction. The radiation hole 39 is opened in the constant-diameter outer peripheral surface 29 of the rotary atomizing head 11 and thus communicates with the annular flow path 34. The rear end (that is, the minimum diameter portion) of the tapered channel 32 communicates with the front end portion of the annular channel 34. The tapered flow path 32 has a tapered shape whose diameter increases toward the front, and the front end thereof is opened at the outer peripheral front end of the rotary atomizing head 11.
[0025]
Further, the front end of the cover 30 constituting the tapered flow path 32 is located behind the front end of the rotary atomizing head 11 and ahead of the ejection port 35. Therefore, the opening 40 at the front end of the tapered flow path 32 (that is, the opening 40 to the outside of the body 10 in the discharge passage 37) is the outer peripheral surface on the opposite side of the outer peripheral edge of the rotary atomizing head 11 from the tapered surface 23. It faces (tapered outer peripheral surface 28). The opening direction of the opening 40 is a direction along the tapered outer peripheral surface 28 of the rotary atomizing head 11, that is, a direction spreading in a trumpet shape.
[0026]
Next, the operation of this embodiment will be described.
When the liquid (paint P or thinner T) supplied from the channel pipe 12 to the storage chamber 17 enters the decompression chamber 38 opposite (rear) from the recess 22 of the rotary atomizing head 11 through the annular gap 27, As shown in FIG. 5, the liquid is given a centrifugal force by high-speed rotation of the rotary atomizing head 11. That is, the liquid is given a centrifugal force by being rotated by the frictional resistance between the liquid and the inner surface of the decompression chamber 38. Then, the liquid is pressed against the inner periphery of the decompression chamber 38 by centrifugal force, flows through the radiation hole 39 to the outer periphery side, moves through the annular channel 34, and moves obliquely forward and outward in the tapered channel 32. It is discharged out of the body 10 through the opening 40 at the front end. Therefore, even if the liquid in the storage chamber 17 leaks rearward through the annular gap 27, it is suppressed or prevented from entering the rear through the inside of the body 10, that is, the annular space 16.
[0027]
In addition, since the turbine air At is fed (forward) toward the discharge passage 37 side (decompression chamber 38) into the annular space 16 extending rearward along the outer periphery of the flow channel pipe 12, this turbine air At. By the pressure, the penetration of the liquid into the rear is more reliably suppressed or prevented. Further, since the turbine air At flows out to the outer periphery of the body 10 through the discharge passage 37, that is, the decompression chamber 38, the radiation hole 39, the annular flow passage 34, and the tapered flow passage 32 in this order, the liquid in the discharge passage 37 flows into the turbine. The air At is multiplied and reliably discharged out of the body 10.
[0028]
In addition, a decompression chamber 38 having a cross-sectional area perpendicular to the flow path pipe 12 larger than the cross-sectional area of the annular gap 27 is provided in a portion of the discharge passage 37 that communicates with the annular gap 27. The liquid (particularly the thinner T) that has passed through the annular gap 27 while being pressurized by being filled is reduced in pressure as it flows into the decompression chamber 38 due to the difference in cross-sectional area between the decompression chamber 38 and the annular gap 27. Is done. Therefore, the liquid can be suppressed or reliably prevented from entering the annular space 16 toward the rear of the body 10.
[0029]
Further, since the opening to the outside of the body 10 in the discharge passage 37 faces the tapered outer peripheral surface 28 on the opposite side of the outer peripheral edge of the rotary atomizing head 11, the taper of the rotary atomizing head 11. The paint P adhering to the outer peripheral surface 28 can be cleaned by the thinner T discharged from the discharge passage 37. Moreover, since the opening 40 of the discharge passage 37 is opened on the tapered outer peripheral surface 28 and the opening direction of the opening 40 is along the tapered outer peripheral surface 28, the cleaning effect by the thinner T is high.
[0030]
[Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, fins 41 are provided inside the decompression chamber 38 constituting the discharge passage 37 in the first embodiment. The fins 41 extend almost straight from the inner peripheral surface of the decompression chamber 38 to the radially inner side (the direction toward the center of the reduced diameter portion 13 of the flow path tube 12), and the plate surface is substantially perpendicular to the rotational direction of the rotary atomizing head 11. Make a plate-like shape. Further, the fin 41 is located at the edge of the opening edge of each radiation hole 39 that is behind the rotational direction of the rotary atomizing head 11 (in FIG. 7, it is shifted in the counterclockwise direction with respect to the center of the radiation hole 39). Edge). The liquid (paint P or thinner T) that has entered the decompression chamber 38 is given a centrifugal force by the rotation of the rotary atomizing head 11 in the clockwise direction in FIG. Therefore, a stronger centrifugal force is applied compared to the case where the centrifugal force is applied by the frictional resistance between the inner surface of the decompression chamber 38 and the discharge of the liquid. Excellent efficiency. In addition, since it is the same as that of the said Embodiment 1 about the structure except the above, the same code | symbol is attached | subjected about the same structure and description of a structure, an effect | action, and an effect is abbreviate | omitted.
[0031]
[Other Embodiments]
The present invention is not limited to the embodiment described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the above embodiment, the air is supplied toward the discharge path side in the space communicating with the discharge path and extending rearward along the outer periphery of the flow path tube. It is good also as a structure which does not supply new air.
[0032]
(2) In the above-described embodiment, the decompression chamber having a cross-sectional area perpendicular to the flow channel pipe larger than the cross-sectional area of the annular gap is provided at the communicating portion with the annular gap in the discharge passage. It is good also as a structure which does not provide a decompression chamber.
(3) In the above embodiment, the air fed toward the discharge path is turbine air for rotationally driving the rotary atomizing head. However, according to the present invention, the turbine air is not diverted and dedicated air is used. You may supply.
[0033]
(4) In the above embodiment, the discharge path is provided inside the rotary atomizing head. However, according to the present invention, at least a part of the discharge path is formed between the rotary atomizing head and the body. It may be.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a coating gun in Embodiment 1. FIG. 2 is an enlarged longitudinal sectional view of a rotary atomizing head. FIG. 3 is a partially enlarged view of FIG. Fig. 5 is an enlarged vertical cross-sectional view showing a state where thinner is supplied to the rotary atomizing head. Fig. 6 is an enlarged cross-sectional view showing a decompression chamber and a radiation hole constituting the discharge passage. FIG. 7 is an enlarged cross-sectional view showing a decompression chamber and a radiation hole constituting the discharge path of Embodiment 2. FIG. 8 is a cross-sectional view of a conventional example.
DESCRIPTION OF SYMBOLS 10 ... Body 11 ... Rotary atomization head 12 ... Channel pipe 17 ... Storage chamber 18 ... Front wall 23 ... Tapered surface 24 ... Small hole 26 ... Center hole 27 ... Annular gap 28 ... Tapered outer peripheral surface (rotating atomization head (Outer peripheral surface opposite to taper surface)
38 ... discharge path 39 ... decompression chamber 40 ... opening of discharge path

Claims (5)

A channel pipe is fixed in the body,
A cup-shaped rotary atomizing head that is rotationally driven concentrically with the flow channel pipe is provided at the front end of the body,
The front end portion of the flow channel pipe passes through the central hole of the rotary atomizing head and faces the storage chamber in the rotary atomizing head,
The liquid supplied from the channel pipe to the storage chamber passes through a small hole in the front wall of the storage chamber and is atomized from the outer periphery thereof along the tapered surface of the rotary atomizing head by centrifugal force. In the paint gun that is supposed to be released,
There is a substantially radial discharge path located behind the annular gap between the outer periphery of the flow channel pipe and the inner circumference of the center hole and communicating with the annular gap and opened to the outside of the body. Provided,
A coating gun characterized in that a centrifugal force is applied to the liquid that has entered the discharge passage by the rotation of the rotary atomizing head. The coating gun according to claim 1, wherein air is supplied toward the discharge path side in a space communicating with the discharge path and extending rearward along the outer periphery of the flow path pipe. The decompression chamber having a cross-sectional area perpendicular to the flow path pipe larger than a cross-sectional area of the annular gap is provided at a portion of the discharge passage that communicates with the annular gap. Item 2. The paint gun according to item 2. 4. The fin according to claim 1, wherein the discharge passage is provided with fins that rotate integrally with the rotary atomizing head to cause the liquid in the discharge passage to flow in a generally circumferential direction. 5. The paint gun described in Crab. The opening to the outside of the body in the discharge path faces the outer peripheral surface of the outer peripheral edge of the rotary atomizing head opposite to the tapered surface. The paint gun described in Crab.

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