JPH07100150B2 - A method for supplying paint to the rotary atomizing head of a sprayer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for supplying a main component of a coating material and a curing agent into a rotary atomizing head of a coating spraying device.

(Prior Art) Conventionally, when a paint is supplied into a rotary atomizing head (hereinafter, simply referred to as an atomizing head), generally, a base material and a curing agent are mixed in advance to form a paint, and this paint is used. The pump is used to feed it into the atomizing head. However, in this method, since the curing time of the coating material by the curing agent is short, the coating material is cured in the supply passage, causing a failure of the pump and the like.

In order to solve this problem, a method has been proposed in which the main agent and the curing agent are supplied into the atomizing head through separate pipes, as disclosed in JP-A-57-45370. However, according to this method, since the two pipes are connected side by side to the atomizing head, the atomizing head becomes large. For this reason, it is difficult to use in a narrow place, which is disadvantageous in coating work, and there is a disadvantage that the work range is saved particularly in the case of coating work by a robot.

(Object of the invention) Therefore, according to the present invention, the main component of the paint and the curing agent can be supplied into the atomizing head in a non-mixed state by a single pipe, and the rotation of the spraying device with good mixing property in the atomizing head is achieved. The present invention provides a method for supplying a paint into a mold atomizing head.

(Structure of the Invention) In the present invention, a single paint supply pipe is exposed from the back side of the atomizing head in the rotary atomizing head, and the main agent and the curing agent for forming the paint are placed in the paint supplying pipe. Each of them flows as a laminar flow in a hierarchical state and is supplied into the rotary atomizing head.

As a result, the main component of the coating material and the curing agent are fed into the atomizing head in a single pipe in an unmixed state, that is, in a state where the curing of the coating material is suppressed.

(Example) FIG. 1 shows an electrostatic coating machine as a spraying apparatus (coating machine) for carrying out the method of the present invention. In the figure,
1 is an atomizing head, 2 is an air bearing turbo motor (hereinafter abbreviated as an air motor) for rotating the atomizing head 1, 3
Is the motor housing.

The atomizing head 1 is composed of a mini bell 11 which is rotationally driven by an air motor 2, a shaping air nozzle 12 which is arranged on the outer circumference of the mini bell 11, and a shaping air ring 13 which is further arranged on the outer circumference of the shaping air nozzle 12. There is. In the mini bell 11, an inner space is formed in a flared shape like a trumpet, a disk-shaped partition plate 14 is provided in the inner space, and a mixing chamber 15 is formed behind the partition plate 14. The partition plate 14 has the ejection holes 14a at a plurality of positions in the circumferential direction of the outer peripheral portion.
, And the paint in the mixing chamber 15 is sprayed forward through the ejection holes 14a by the centrifugal force caused by the rotation of the minibell 11.

On the other hand, an air passage 16 is formed between the shaping air nozzle 12 and the shaping air ring 13.
Is connected to a high-pressure air supply source such as a compressor via an air passage formed in the motor housing 3 and an air supply pipe (not shown) connected to the air passage. With these, the shaping system is configured, and the spray angle of the paint from the minibell 11 is regulated to a constant value by the high pressure air ejected from the tip of the atomizing head 1 through the air passage 16.

The air motor 2 is fixed to a stator 21 fixed to the inner space of the motor housing 3, a hollow rotary shaft 22 inserted through the center of the stator 21, and a rear end of the rotary shaft 22. The mini bell 11 of the atomizing head 1 is attached to the tip of the rotary shaft 22 so as to rotate integrally with the rotary shaft 22.
The rotary shaft 22 rotates at high speed when high pressure air is blown onto the fins 23 from behind. The rotary shaft 22 is rotatably supported by an air bearing, that is, high pressure air blown into the gap between the rotary shaft 22 and the stator 21.

Further, in the motor housing 3, a joint member 4 is provided behind the air motor 2, and the joint member 4, the stator 21 of the air motor 2 and the motor housing 3 are connected by connecting bolts 5a and 5b. On the stator 21, the high voltage cable 6 introduced into the motor housing 3 is spring-loaded.
A high voltage is applied to the minibell 11 of the atomizing head 1 through the stator 21, the rotary shaft 22, making contact via 61 and the connector pin 62. This high voltage negatively charges the paint in the minibell 11, and the sprayed paint is adsorbed to the grounded surface to be painted.

7 is a paint on the mini bell 11 of the atomizing head 1 (main agent and curing agent)
This paint supply pipe 7
Is inserted into the hollow part of the rotary shaft 22 and its front end is
It is introduced into the mixing chamber 15 of 11 from the back side, and the rear end is introduced into the joint member 4. The joint member 4 is provided with a first passage 41 linearly continuous to the rear end of the paint supply pipe 7 and a second passage 42 extending in a direction perpendicular to the pipe 7. On the other hand, the first passage 31 and the second passage 32 are also formed in the motor housing 3 so as to communicate with the first passage 41 and the second passage 42 of the joint member 4, respectively. A main agent supply hose 8 is connected to 31 and a curing agent supply hose 9 is connected to the second passage 32. The main agent supply hose 8 is connected to the main agent tank containing the main agent, and the hardener supply hose 9 is connected to the hardener tank containing the hardener via a pump or the like (this connection system will be described later). Through the main agent supply hose 8 and the first passages 31 and 41, the curing agent is supplied with the curing agent supply hose 9,
It is sent to the paint supply pipe 7 through the second passages 32 and 42, and is supplied to the mixing chamber 15 of the minibell 11 through the pipe 7.

At this time, the main agent and the curing agent are in a laminar flow state in the paint supply pipe 7, and flow in the pipe 7 in a layered state in which the main agent layer and the curing agent layer are separated. In other words, the supply conditions (the number of Reynolds) for the main agent and the curing agent are set so as to obtain this hierarchical state.

The Reynolds number Re is given by Re = Duρ / μ in the relationship of D: inner diameter of the paint supply pipe 7, u: flow velocity, ρ: density, μ: viscosity, and this Reynolds number is a certain value (critical Reynolds number) Laminar flow occurs in the range not exceeding. When both the main agent and the curing agent are in this laminar flow state, they flow in the coating supply pipe 7 in a layered state in which the main agent layer and the curing agent layer are divided into upper and lower layers as shown in FIG. . In FIG. 2, the black portions show the flow of the curing agent, and the white portions show the flow of the main agent.

Further, in FIG. 3, as a supply pattern suitable when the mixing ratio of the curing agent is small, the curing agent flows linearly in the central portion of the paint supply pipe 7 and the main agent flows around it in a hierarchical state. The supply pattern is shown. In this case, the first passages 31 and 41 of the motor housing 3 and the joint member 4 are passages of the hardening agent, and the second passages 32 and 42 are passages of the main agent. The first passage 41 of the joint member 4 is narrowed at its tip end so that the curing agent enters the center of the pipe.

In this way, the main agent and the curing agent are combined into a single paint supply pipe 7
Since it is supplied to the mini-bell 11 of the atomizing head 1, the space to be secured in the atomizing head 1 for this pipe connection is small, and the atomizing head 1 can be downsized accordingly. Moreover, since the main agent and the curing agent flow in the paint supply pipe 7 in a hierarchical state, that is, in a state where they do not mix with each other,
The curing reaction in this pipe is suppressed.

In this way, the main agent and the curing agent that flow in the paint supply pipe 7 in a layered state enter the mixing chamber 15 of the minibell 11, are mixed by centrifugal force, and are sprayed from the minibell 11. In this case, since the main agent and the curing agent are sent from the same paint supply pipe 7 to the same position of the mixing chamber 15 so as to overlap with each other, the main agent and the curing agent are sent to different positions from different pipes as in the conventional case. As compared with the case of the above, the mixing property is good, and a good mixed state in which the main agent and the curing agent are evenly mixed can be obtained. That is, the base material and the curing agent are suppressed from being mixed in the paint supply pipe 7, and are efficiently mixed when exiting the pipe 7. It should be noted that if the tip end of the paint supply vibrator 7 is bent so as to be narrowed as shown in the drawing, the base material and the curing agent enter the mixing chamber 15 while overlapping each other, so that the mixing property is further improved. Further, since the mixing property is good as described above, a good coating finish state without so-called color unevenness can be obtained even after spraying.

By the way, a paint supply and cleaning system for the above-mentioned coating machine is illustrated in FIG. Here, two types (two colors) of the main agent are used properly according to the object to be coated.

A is a first main agent tank, B is a second main agent tank, C is a hardening agent tank, and the outlets of both the first and second main agent tanks A and B are
_They are connected to the first joint G ₁ via paint pressure pumps D ₁ and D ₂ , regulators E ₁ and E ₂ for flow rate control, and on-off valves F ₁ and F ₂ , respectively, and the main agent is at the outlet of the first joint G _1. The supply hose 8 is connected. Further, the outlet of the hardener tank C is connected to the second joint via the hardener pressure pump D ₃ , the regulator E ₃ , and the opening / closing valve F _3.
Is connected to G _2, the second outlet of the joint G ₂ is connected to a hardener supply hose 9. Thus, when painting, the on-off valve
By the switching operation of F ₁ and F ₂ , the first main agent or the second main agent,
Curing agent, respectively, by opening operation of the opening and closing valve F ₃ atomizing head 1
To be supplied to.

On the other hand, H is a thinner tank for cleaning, a thinner pressure pump D ₄ is connected to the outlet of this thinner tank H, the outlet of this pump D ₄ is branched into two, and one is the first through the on-off valve F ₄ . The joint G ₁ is connected to the second joint G ₂ via the open / close valve F 5. Further, I is a cleaning air pump, and the outlet of this pump I is branched into two, one is to the first joint G ₁ via the on-off valve F ₆ and the other is to the second joint G via the on-off valve F _{7. 2} connected to each. In this way, the thinner and the air are alternately flown into the paint supply passage to clean the same passage.

In the above embodiment, the main agent and the curing agent are made to flow in the upper and lower layers except when the curing agent flows in the center of the paint supply pipe, but they may be made to flow in the left and right layers.

(Effects of the Invention) As described above, according to the present invention, a single paint supply pipe is made to face the inside of the atomizing head from its back side, and the main agent and the curing agent for forming the paint are supplied to this single paint supply. The pipe connection space of the atomizing head can be small because it flows in the pipe in a hierarchical state and is supplied into the atomizing head. Therefore, since the atomizing head can be downsized, it is easy to use even in a narrow space, and the working range by the robot is widened, which is advantageous in coating work. Moreover,
Even though the paint supply pipe is single, the main agent and the curing agent do not mix in the same pipe, so that it is possible to suppress the curing reaction of these to reach the atomizing head. In addition, since the main agent and the curing agent are fed into the atomizing head in a layered state, they are quickly and efficiently mixed in the atomizing head, resulting in a good mixed state without unevenness of mixing and a good coating finish state. Is what you can get.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a spraying device (coating machine) for carrying out the method of the present invention, FIGS. 2 and 3 are drawings for explaining two examples of a paint supply method by the device, and FIG. 4 is a paint. It is a figure which shows the whole structure of a supply system. 1 ... atomizing head, 11 ... minibell with atomizing head, 15 ... minibell mixing chamber, 7 ... paint supply pipe.

Claims (1)

[Claims] 1. A single paint supply pipe is faced in the rotary atomization head from the back side of the atomization head, and a main agent and a curing agent for forming the paint are respectively laminarly flowed in the paint supply pipe. A method for supplying paint into the rotary atomizing head of a spraying device, characterized in that the paint is supplied in the rotary atomizing head in a layered state.