JP2013188651A - Rotary atomization type electrostatic coating machine and head member therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a paint mist included in the atmosphere around a rotary atomization head and a head member from entering an inner circumferential space between the atomization head and the head member.SOLUTION: A head member includes a plurality of shaping air discharge ports 12 and a plurality of second air discharge ports 16, which are formed on a common circumference, the second air discharge ports 16 being disposed at the midpoint each between two adjacent shaping air discharge ports 12, 12. The diameter Dbr of the second air discharge port 16 is smaller than the diameter Dsa of the shaping air discharge port 12, and the amount of air discharged from the second air discharge port 16 is smaller than the amount of shaping air. An air flow discharged from the second air discharge port 16 forms an air barrier to prevent a paint mist from entering an inner circumferential space through a gap between the adjacent shaping air discharge ports 12, 12.

Description

  The present invention relates to a rotary atomizing electrostatic coating machine and a head member thereof.

  Electrostatic coating is a coating method that uses a charged paint, and a rotary atomizing electrostatic coating machine equipped with a rotary atomizing head is widely used especially for painting automobile bodies.

  In the rotary atomizing electrostatic coating machine, the painting operation is performed as follows. The electrostatic coating machine that applies high voltage to the atomizing head will be described as an example. When paint is supplied to the central part of the rotating atomizing head (bell cup), the paint is applied to the front surface of the atomizing head. Spreads outward in the radial direction and is atomized when scattered from the outer peripheral edge of the atomizing head toward the space. The scattered paint is charged, and the fine paint in the charged state flies toward the object to be coated in the ground state or reverse polarity. An air stream is used to define the spread of paint that scatters from the outer periphery of the atomizing head and to transport it toward the workpiece. This air flow is called “shaping air”, and the shaping air is discharged forward from the front end of the coating machine main body.

  Patent Document 1 proposes an improvement plan related to electrostatic coating of metallic paint including metallic pieces such as aluminum pieces and mica. Metallic paint increases the discharge rate of shaping air based on the knowledge that the lightness of the coating increases as the speed at which it collides with the workpiece increases. There is a problem that coating unevenness occurs and the finished quality deteriorates. The invention proposed in Patent Document 1 aims at preventing the coating pattern width from becoming smaller even when the discharge amount of the shaping air is increased, and the shaping air toward the rotary atomizing head, that is, the outer periphery of the bell cup. It is proposed that the shaping air discharge port is directed in the forward or reverse twist direction with respect to the axis of the rotation axis of the bell cup. According to this proposal, the shaping air becomes an air flow that draws a spiral trajectory, and the coating pattern is brought inward by overcoming the suction force due to the negative pressure generated in the front area of the bell cup by the centrifugal force of this spiral air flow. It can be prevented from being drawn.

  Patent Document 2 proposes an invention aimed at improving the problem of overspray when painting a narrow part of an automobile body. Specifically, in the invention of Patent Document 2, the control air discharge port is arranged on the outer peripheral side adjacent to the shaping air discharge port and the control air is located on the outer peripheral side of the shaping air that is a swirling flow. It has been proposed to make the absolute value of the inclination angle of the air discharge port larger than the inclination angle of the shaping air discharge port. According to the invention of this patent document 2, the control air is shaped air by setting the absolute value of the inclination angle of the control air discharge port located in the vicinity of the shaping air discharge port to be larger than the inclination angle of the shaping air discharge port. The degree of turning can be strengthened compared to the above, and the width of the coating pattern can be variably controlled by relatively increasing or decreasing the amount of control air and the amount of shaping air.

JP-A-3-101858 JP 2008-93521 A

  In the rotary atomizing electrostatic coating machine, a problem associated with discharging the shaping air from the port located behind the atomizing head to the front will be described with reference to FIG. In the figure, reference numeral 500 indicates a conventional rotary atomizing electrostatic coating machine, reference numeral 502 indicates a rotary atomizing head, and reference numeral 504 indicates a head member (shaping air ring). The head member 504 has a plurality of shaping air discharge ports 506 arranged at equal intervals on the same circumference, and the shaping air SA is discharged forward from the shaping air discharge port 506.

  Since the shaping air SA moves forward while involving the atmosphere on the outer peripheral side, an accompanying flow A is generated in the atmosphere on the outer peripheral side. On the other hand, in the inner circumferential space 508 of the shaping air SA, that is, the inner circumferential space 508 sandwiched between the atomizing head 502 and the head member 504, the air present in the inner circumferential space 508 is drawn into the shaping air SA. Therefore, it becomes a negative pressure state.

  FIG. 9 is a plan view of the head member 504 as viewed from above. When the shaping air SA is discharged from the port 506, the shaping air SA advances forward while gradually expanding, so that a gap SP is generated between the adjacent ports 506, 506 in the vicinity of the shaping air discharge port 506. That is, in the vicinity of the port 506, a gap SP is generated between the shaping air SA discharged from one shaping air discharge port 506 and the shaping air SA discharged from another shaping air discharge port 506 adjacent thereto. To do.

  As described above, the accompanying flow A is generated on the outer peripheral side of the shaping air SA, while the inner peripheral space 508 of the shaping air SA is in a negative pressure state (FIG. 8). For this reason, a phenomenon occurs in which the atmosphere on the outer periphery side of the shaping air SA flows toward the inner space 508 through the gap SP between the adjacent shaping air SAs. An intrusion air flow entering the inner peripheral side through the gap SP is indicated by a reference sign B in FIG.

  By the way, in the process of coating the object to be coated, the paint mist M is generated around the coating machine 500. A part of the paint mist M enters the accompanying flow A described above. A part of the paint mist M mixed in the accompanying flow A enters the inner circumferential space 508 sandwiched between the atomizing head 502 and the head member 504 through the gap SP together with the intruding air flow B. The tip surface of the head member 504 and the back surface of the rotary atomizing head 502 are soiled.

  The phenomenon in which the paint mist M adheres to the head member 504 and the atomizing head 502 becomes a factor that deteriorates the coating quality. This point will be described. The paint mist M easily accumulates on the front end surface of the head member 504, the rear surface of the atomizing head 502, and particularly the front end surface of the head member 504 that is not rotating. Then, it peels off from the head member 504, and this lump of paint is mixed into the shaping air SA and carried to the object to be coated.

  An object of the present invention is to provide a rotary atomizing electrostatic that can suppress the coating mist generated around the coating machine during operation of the coating machine from entering the inner circumferential space between the atomizing head and the head member. It is providing a coating machine and its head member.

The above technical problem is, according to the first aspect of the present invention,
A rotary atomizing electrostatic coating machine having a rotary atomizing head located adjacent to the front of the head member;
A plurality of shaping air discharge ports that are formed on the head member and are arranged at equal intervals on a circumference concentric with the rotation axis of the rotary atomizing head and discharge shaping air toward the front;
A second air discharge port formed in the head member and disposed in an intermediate portion between the two shaping air discharge ports adjacent to each other;
Provided is a rotary atomizing electrostatic coating machine characterized in that an air barrier is generated in a gap between two adjacent shaping airs by the second air discharged forward from the second air discharge port. Is achieved.

  That is, since the air barrier is formed in the gap between the shaping air discharge ports adjacent to each other by the second air, the paint mist generated around the coating machine during the operation of the coating machine is caused by the atomization head and the head member. It is possible to suppress the intrusion into the inner circumferential space between the two.

  The second air discharge port may be formed on the same circumference as the shaping air discharge port, or may be located on the outer peripheral side of the shaping air discharge port.

  In a preferred embodiment of the present invention, the third air discharge located on the inner peripheral side of the shaping air discharge port and opened toward the inner peripheral space between the rotary atomizing head and the tip surface of the head member. A port is formed in the head member, and by discharging third air from the third air discharge port, the negative pressure in the inner circumferential space between the rotary atomizing head and the tip surface of the head member is reduced. can do.

  Other objects and advantages of the present invention will become apparent from the detailed description of the preferred embodiments of the present invention.

It is sectional drawing of the front-end part of the rotary atomization type electrostatic coating machine of 1st Example. It is the figure which looked at the some shaping air discharge port and several 2nd air discharge port which were formed in the head member of the electrostatic coating machine of 1st Example from the front. It is the elements on larger scale which expanded and extracted a part of FIG. It is a figure for demonstrating the effect | action of the rotary atomization type electrostatic coating machine of 1st Example, and is the figure which looked at the front-end part of the coating machine from the top. It is sectional drawing of the front-end part of the rotary atomization type electrostatic coating machine of 2nd Example. It is the figure which looked at the some shaping air discharge port and several 2nd air discharge port which were formed in the head member of the electrostatic coating machine of 2nd Example from the front. It is the elements on larger scale which expanded and extracted a part of FIG. It is a figure for demonstrating the problem in the conventional rotary atomization type electrostatic coating machine. In the shaping air discharged from the shaping air discharge port included in the conventional rotary atomizing electrostatic coating machine, it is a diagram for explaining that a gap is formed between adjacent shaping air. It is the figure which looked at the front-end part of the machine from the top.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First Example (FIGS. 1 to 4) :
1 to 4 show a rotary atomizing electrostatic coating machine 100 according to a first embodiment. FIG. 1 is a cross-sectional view of the front portion of the electrostatic coating machine 100. The rotary atomizing electrostatic coating machine 100 has a rotary atomizing head 2, and this electrostatic coating machine 100 is attached to a robot arm (not shown) or the like installed in a painting booth for painting the body of an automobile. Installed. Since the rotary atomizing head 2 is generally called “bell cup”, the term “bell cup” is used in the following description.

  The electrostatic coating machine 100 incorporates an air motor (not shown) of the coating machine body 4. A bell cup 2 is detachably connected to the output shaft of the air motor, and the bell cup 2 rotates in one direction when the air motor operates. The rotational axis of the bell cup 2 is indicated by reference symbol Ax.

  The bell cup 2 has an inner surface 2a composed of a recess opened toward the front side, and a back surface 2b constituted by an inclined outer peripheral surface whose diameter increases toward the front side. The inner surface 2a of the bell cup 2 has a spreading function for developing the paint in a thin film state along the inner surface 2a.

  The head member 10 constituting the front end portion of the coating machine main body 4 is located adjacent to the rear of the bell cup 2, and in the electrostatic coating industry, the head member 10 may be referred to as “shaping air ring”. In the head member, that is, the shaping air ring 10, a shaping air discharge port 12 is opened forward. The coating pattern is substantially defined by the shaping air SA discharged from the shaping air discharge port 12.

  A plurality of shaping air discharge ports 12 are arranged at equal intervals on a circumference concentric with the rotation axis Ax of the bell cup 2. Reference numeral 14 in FIG. 1 denotes a first chamber, and air is supplied to the shaping air discharge port 12 through the first chamber 14. The coating pattern is substantially defined by the shaping air SA discharged from the shaping air discharge port 12.

  FIG. 2 shows the shaping air discharge port 12 when the head member 10 is viewed from the front. As described above, a plurality of the shaping air discharge ports 12 are arranged at equal intervals on the circumference concentric with the rotation axis Ax of the bell cup 2. As can be seen from FIG. 2, the second air discharge port 16 is disposed between the adjacent shaping air discharge ports 12 and 12 on the common circumference. Air is supplied to the second air discharge port 16 through the first chamber 14 (FIG. 1).

  Here, the number of shaping air discharge ports 12 is “37” as in the prior art, and the number of second air discharge ports 16 is also “37”. Since the diameter of the bell cup 2 is 70 mm, the pitch between the two adjacent shaping air discharge ports 12 and 12 is about 6 mm as in the prior art. And the pitch between the 2nd air discharge port 16 in the middle and the shaping air discharge port 12 is about 3 mm. That is, in the head member 10 included in the first embodiment, the shaping air discharge ports 12 and the second air discharge ports 16 are alternately formed at a pitch of about 3 mm on the same circumference.

  A plurality of types of bell cups 2 having different sizes are known as bell cups used in a rotary atomizing electrostatic coating machine for automobiles. Specifically, a first type having a diameter of 50 mm, a second type having a diameter of 70 mm, a third type having a diameter of 80 mm, and the like. In a coating machine equipped with a first type bell cup, the shaping air discharge ports 12 are generally arranged at a pitch of 4.2 mm. In a coating machine equipped with the second type bell cup, the shaping air discharge ports 12 are generally arranged at a pitch of 6 mm. In a coating machine equipped with a third type bell cup, the shaping air discharge ports 12 are generally arranged at a pitch of 6.3 mm.

  When the present invention is applied to various types of electrostatic coating machines for automobiles having a plurality of types of bell cups 2 having different sizes, in the first type, the shaping air discharge port 12 and the second air discharge port are arranged at a pitch of 2.1 mm. 16 are arranged. In the second type, the shaping air discharge port 12 and the second air discharge port 16 are arranged at a pitch of 3 mm. In the third type, the shaping air discharge port 12 and the second air discharge port 16 are arranged at a pitch of 3.15 mm.

  The diameter Dsa of the shaping air discharge port 12 and the diameter Dbr of the second air discharge port 16 will be described. The diameter Dsa of the shaping air discharge port 12 is 0.8 mm (Dsa = 0.8 mm), and the second air discharge port 16 The diameter Dbr is 0.5 mm (Dbr = 0.5 mm). That is, the diameter Dbr of the second air discharge port 16 is preferably smaller than the diameter Dsa of the shaping air discharge port 12 (Dbr <Dsa). As a modification, the diameter Dbr of the second air discharge port 16 and the diameter Dsa of the shaping air discharge port 12 may be set equal. That is, the ratio of the hole diameter between the diameter Dbr of the second air discharge port 16 and the diameter Dsa of the shaping air discharge port 12 is preferably 0.5 to 1.0.

  If the amount of air discharged from the second air discharge port 16 is smaller than the amount of air discharged from the shaping air discharge port 12, the amount of air consumption can be reduced. When the diameter Dbr of the second air discharge port 16 is set small, the discharge pressure of air discharged from the second air discharge port 16 is greater than the discharge pressure of air discharged from the shaping air discharge port 12 due to pressure loss due to the hole diameter. Also lower.

  As can be seen from FIG. 1, the shaping air discharge port 12 is directed to the outer peripheral edge 2 c of the bell cup 2. The shaping air discharge port 12 may be oriented in the forward or reverse twist direction with respect to the rotation axis Ax of the bell cup 2 as in the above-described Patent Documents 1 and 2, or the outer peripheral edge 2c of the bell cup 2 It may be an air flow that advances linearly toward.

  In this embodiment, the shaping air SA discharged from the shaping air discharge port 12 is set so as to advance linearly toward the outer peripheral edge 2c of the bell cup 2, but the rotation direction of the bell cup 2 is defined as follows. Shaping air SA that turns in the opposite direction may be used.

  FIG. 4 is a schematic view corresponding to FIG. 9 described above, with the head member 10 viewed from above. 4 and FIG. 9, the gap between the adjacent shaping air discharge ports 12 and 12 is the second air flow 20 from the second air discharge port 16 so as to fill the gap SP. You will see that it is discharging. When this second air flow 20 is referred to as a “barrier flow”, the barrier flow 20 discharged from the second air discharge port 16 fills the gap SP between the adjacent shaping air SA and enters the intrusion air flow shown in FIG. It functions as an “air barrier” that blocks B.

  That is, the barrier flow 20 is positioned closer to both of these two adjacent shaping airs SA and SA than the pitch of one conventional shaping air SA and the other shaping air SA adjacent thereto. Then, an air barrier is generated in the gap SP between the two adjacent shaping air SAs, and by this air barrier, the paint mist M (FIG. 8) scattered around the coating machine 100 passes through the gap SP and forms the shaping air SA. Intrusion into the inner peripheral space 22 can be suppressed. This means that the contamination of the front end surface of the head member 10 can be reduced and the coating quality can be improved.

  If the diameter Dbr of the second air discharge port 16 that discharges the barrier flow 20 is set to a value smaller than the diameter Dsa of the shaping air discharge port 12 (Dbr <Dsa), the second air discharge port 16 is added. The increase in the air consumption accompanying it can be suppressed. As a modified example, the shaping air discharge port 12 and the second air discharge port 16 are set to have the same hole diameter, and the amount of air discharged from the shaping air discharge port 12 and the second air discharge port 16 is relatively compared to the conventional case. It may be made smaller.

  Referring to FIG. 1 again, reference numeral 30 indicates a third air discharge port. The third air discharge port 30 is opened toward the inner circumferential space 22 between the tip surface of the head member 10 and the bell cup 2. As a preferred embodiment, the third air discharge port 30 is directed in a direction inclined radially inward toward the rotation axis Ax of the bell cup 2. Air is supplied from the third air chamber 32 to the third air discharge port 30. The third air flow discharged from the third air discharge port 30 is for the purpose of reducing the negative pressure generated in the inner circumferential space 22 described above, and a relatively small amount of air that can achieve this purpose. Is discharged from the third air discharge port 30.

  As described above, the third air flow discharged from the third air discharge port 30 plays a role of reducing the negative pressure in the inner circumferential space 22 defined by the front end surface of the head member 10. Therefore, you may comprise the 3rd air discharge port 30 by the shape of a channel | path which spreads wide toward the opening end (front-end | tip).

  Whether or not the third air discharge port 30 is provided in the head member 10 is arbitrary. However, when the third air discharge port 30 is provided, the third air is discharged toward the inner circumferential space 22 as described above. The negative pressure in the inner circumferential space 22 can be reduced. If the negative pressure in the inner circumferential space 22 is reduced, the force to draw the paint mist M (FIG. 8) located on the outer circumferential side of the shaping air SA to the radially inner side through the gap SP described above becomes weaker, so the inner circumferential side. The amount of the paint mist M entering the space 22 can be reduced. Therefore, by forming the third air discharge port 30 in the head member 10, contamination of the front end surface of the head member 10 can be reduced.

  As a modification of the first embodiment, the shaping air discharge port 12 may be directed to the back surface 2b of the bell cup 2 and the shaping air SA may be applied to the back surface 2b of the bell cup 2.

Second Example (FIGS. 5 to 7) :
5 to 7 show a rotary atomizing electrostatic coating machine 200 of the second embodiment. In the description of the second embodiment, the same elements as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, the characteristic portions of the second embodiment will be mainly described.

  In the head member 40 included in the second embodiment, the second air discharge port 16 is disposed on the outer peripheral side of the shaping air discharge port 12. The shaping air discharge port 12 and the second air discharge port 16 are both directed toward the outer peripheral edge 2 c of the bell cup 2. The shaping air SA and the barrier flow 20 may be a swirl flow that swirls in the direction opposite to the rotation direction of the bell cup 2 or may be a straight flow that goes straight straight.

  6 is a view for explaining the relationship between the shaping air discharge port 12 and the second air discharge port 16 when the head member 40 is viewed from the front, and FIG. 7 is a partially enlarged view of a part thereof. It is.

  With reference to FIGS. 6 and 7, the head member 40 has a plurality of shaping air discharge ports 12 on its front end surface, and the plurality of shaping air discharge ports 12 are concentric with the rotation axis Ax of the bell cup 2. It is formed on the circumference of 1 at regular intervals, and the number thereof is “37” as in the first embodiment. On the other hand, the second air discharge port 16 is formed on the outer peripheral side of the shaping air discharge port 12, and is formed at equal intervals on the second circumference concentric with the rotation axis Ax of the bell cup 2. “37”, which is the same number as the shaping air discharge port 12. The diameter of the bell cup 2 is 70 mm as in the first embodiment. Therefore, the shaping air discharge ports 12 are arranged at a pitch of about 6 mm on the first circumference. Similarly, the second air discharge ports 16 are arranged at a pitch of about 6 mm on the second circumference.

  The second air discharge port 16 is preferably arranged at a position corresponding to the middle between two adjacent shaping air discharge ports 12. Thereby, as can be seen from FIGS. 6 and 7, the shaping air discharge port 12 and the second air discharge port 16 have a staggered arrangement relationship. In other words, it is preferable that the adjacent two shaping air discharge ports 12 and 12 and the second air discharge port 16 positioned therebetween have an arrangement relationship in which these three ports constitute three vertices of an isosceles triangle. In this case, the pitch between the shaping air discharge port 12 and the second air discharge port 16 is substantially about 3 mm.

  The diameter Dsa of the shaping air discharge port 12 and the diameter Dbr of the second air discharge port 16 are both the same as in the first embodiment, and the diameter Dsa of the shaping air discharge port 12 is 0.8 mm (Dsa = 0.8 mm). The diameter Dbr of the second air discharge port 16 is 0.5 mm (Dbr = 0.5 mm).

  Returning to FIG. 5, the shaping air discharge port 12 is supplied with air from the above-described chamber 14, while the second air discharge port 16 is supplied with air from the second chamber 32. The discharge pressure of the barrier flow 20 discharged from the second air discharge port 16 in order to supply the air to the second air discharge port 16 through the second chamber 32 independent of the first chamber 14 that supplies air to the shaping air discharge port 12. And the amount of discharge can be easily adjusted.

  In the electrostatic coating machine 200 of the second embodiment, the barrier flow 20 is discharged from the second air discharge port 16 located on the outer peripheral side of the gap SP between the shaping air discharge ports 12 and 12 and adjacent thereto. The barrier flow 20 generates an air barrier adjacent to and on the outer peripheral side of the gap SP between two adjacent shaping airs SA. As in the first embodiment, the air barrier causes the paint mist M (FIG. 8) scattered around the coating machine 200 to enter the inner circumferential space 22 of the shaping air SA through the gap SP. Can be suppressed.

  Also in the second embodiment, the third air discharge port 30 described in the first embodiment is formed in the head member 40, and the third air discharged from the third air discharge port 30 causes the inner circumferential side space 22 to be formed. The negative pressure may be reduced. Further, the shaping air SA discharged from the shaping air discharge port 12 may be applied to the back surface 2 b of the bell cup 2.

100 Electrostatic coating machine of the first embodiment 200 Electrostatic coating machine of the second embodiment 2 Rotating atomizing head (bell cup)
10 Head member 12 Shaping air discharge port SA Shaping air 16 Second air discharge port 20 Second air (air barrier)
Ax Bell cup axis of rotation Dsa Diameter of shaping air discharge port Dbr Diameter of second air discharge port

Claims (9)

A rotary atomizing electrostatic coating machine having a rotary atomizing head located adjacent to the front of the head member;
A plurality of shaping air discharge ports that are formed on the head member and are arranged at equal intervals on a circumference concentric with the rotation axis of the rotary atomizing head and discharge shaping air toward the front;
A second air discharge port formed in the head member and disposed in an intermediate portion between the two shaping air discharge ports adjacent to each other;
A rotary atomizing electrostatic coating machine, wherein an air barrier is generated in a gap between two shaping airs adjacent to each other by the second air discharged forward from the second air discharge port.   The rotary atomizing electrostatic coating machine according to claim 1, wherein the second air discharge port is formed on a common circumference with the shaping air discharge port. The plurality of shaping air discharge ports are arranged at equal intervals on a first circumference concentric with the rotation axis of the rotary atomizing head,
The plurality of second air discharge ports are arranged at equal intervals on a second circumference located on the outer circumference side of the first circumference and concentric with the rotation axis of the rotary atomizing head,
The rotary atomizing electrostatic coating machine according to claim 1, wherein the plurality of shaping air discharge ports and the plurality of second air discharge ports are alternately arranged.   The rotary atomizing electrostatic coating machine according to any one of claims 1 to 3, wherein a diameter of the second air discharge port is smaller than a diameter of the shaping air discharge port.   The rotary atomizing electrostatic coating machine according to any one of claims 1 to 3, wherein a diameter of the second air discharge port is equal to a diameter of the shaping air discharge port.   The rotary atomizing electrostatic coating machine according to claim 4, wherein an amount of the second air discharged from the second air discharge port is smaller than an amount of the shaping air discharged from the shaping air discharge port. A third air discharge port formed on the head member, located on the inner peripheral side of the shaping air discharge port, and opened toward an inner peripheral space between the rotary atomizing head and the front end surface of the head member. Further comprising
The negative pressure in the inner circumferential space between the rotary atomizing head and the tip surface of the head member is reduced by the third air discharged from the third air discharge port. A rotary atomizing electrostatic coating machine according to claim 1. A head member included in the rotary atomizing electrostatic coating machine according to any one of claims 1 to 6,
The shaping air air discharge port;
A head member comprising the second air discharge port. A head member included in the rotary atomizing electrostatic coating machine according to claim 7,
The shaping air air discharge port;
The second air discharge port;
A head member comprising the third air discharge port.

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