JPS62176573A - Painting method lising rotary atomizing electrostatic painting apparatus - Google Patents

Abstract

PURPOSE:To enable painting imparting a uniform film thickness without generating dripping, by controlling shaving air pressure further corresponding to the properties of paint in addition to the surface area and surface shape of a part to be painted. CONSTITUTION:In controlling the expanse angle of paint spraying by shaving air, when an article to be painted is a car, it is determined whether the pressure of shaving air is H (high pressure) or L (low pressure) at first corresponding to the kind of the car and, subsequently, pressure regulating valves A-D to be used corresponding to paint are determined with respect to H and L. At the time of painting, when either one of the solenoid opening and closing valves 49-52 are opened on the basis of the output signal of a control apparatus 30, pilot air is supplied to the corresponding one of the pilot air chambers 41-44 of the corresponding opening and closing valves 37-40. As a result, either one of the opening and closing valves receiving the supply of air is opened and the shaving air regulated in its pressure by the corresponding one of the pressure regulating valves A-D is injected from an air jet orifice.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a coating method using a rotary atomizing electrostatic coating device.

[Conventional technology]

Shaving air is ejected from behind the spray head that rotates at high speed, passing around the outer circumferential surface of the spray head toward the front, and by changing the pressure of this shaving air, the spread angle of the paint spray is controlled. Electrostatic coating equipment is known (see Japanese Patent Publication No. 58-22262).

In this rotary atomizing electrostatic coating device, when the amount of paint discharged increases and the spread angle of the paint spray becomes too large, the shaving air pressure is increased to keep the spread angle of the paint spray within a certain angle range. ing.

[Problem to be solved by the invention]

However, in reality, the viscosity of each paint differs, so even if the amount of paint discharged is the same, the spread angle of the paint will change if the paint is different. Therefore, even if the shaving air pressure is simply controlled according to the amount of paint discharged as described above, the spread angle of the paint spray will become too large, causing the paint film to become locally thin or the spread angle of the paint spray to become too small. There is a problem in that too much paint is applied locally, resulting in paint dripping on the surface to be painted.

[Means for solving problems]

In order to solve the above problems, according to the present invention, shaving air is ejected from behind the spray head rotating at high speed, passing around the outer circumferential surface of the spray head toward the front, and controlling the spread angle of the paint spray with the shaving air. In a controlled coating method using a rotary atomizing electrostatic coating device, the shaving air pressure is controlled depending on the surface area and shape of the object to be coated and the type of paint to be coated.

〔Example〕

Referring to FIG. 1, l is the main body of the rotary atomizing electrostatic coating device;
2 indicates a housing, and 3 indicates a spray head.

Referring to FIG. 2, which is an enlarged sectional view of the rotary atomizing electrostatic coating device main body l, a rotating shaft 4 is rotatably supported within the housing 2, and a spray head 3 is mounted on the protruding tip of the rotating shaft 4. is fixed. This rotating shaft 4 is rotated at high speed by an air motor (not shown). The spray head 3 has an annular space 5 around the axis of rotation and a cup-shaped inner peripheral surface 6 inside thereof.

A large number of paint outflow holes 7 extending radially outward are formed in the innermost part of the annular space 5, and these paint outflow holes 7 open tangentially to the base of the cup-shaped inner peripheral surface 6. A nozzle opening 9 of a paint supply nozzle 8 is arranged in the annular space 5, and paint is supplied from the nozzle opening 9 into the annular space 5 of the spray head 3 rotating at a high speed. This paint flows out onto the base of the cup-shaped inner peripheral surface 6 through the paint outlet hole 7, and then spreads on the cup-shaped inner peripheral surface 6 in the form of a thin film. The paint spread in the form of a thin film is released from the tip of the cup-shaped inner circumferential surface 6 in the form of fine paint particles. On the other hand, the housing 2 is connected to a high voltage generator (not shown), and a negative high voltage is applied to the housing 2. This negative high voltage is further applied to the spray head 3 via the rotating shaft 4. Therefore, the paint particles ejected from the tip of the cup-shaped inner circumferential surface 6 are negatively charged when ejected. These negatively charged paint particles spread outward in the radial direction, as shown by the chain line a, toward the object to be painted in front.

On the other hand, an end plate 10 is fixed to the front end of the housing 2,
An annular shaving air chamber 11 is formed within the end plate 10. The compressed air supplied into the shaving air chamber 11 from the shaving air supply holes 12 flows through a large number of shaving air jet holes 13 formed on the front end surface of the end plate 10.
From there, as shown by arrow C, the spray passes around the outer peripheral surface of the spray head 3 and is ejected forward. This shaving air suppresses the spread angle of the paint spray from the large spread angle shown by the chain line a to the small spread angle shown by the chain line.

The paint supply nozzle 8 is connected via a paint supply conduit 20 to a paint color change device 21 shown in FIG. This paint color changing device 21 has paint tanks 22 each storing paints of different colors.
, 23 , 24 , and 25 are connected to a plurality of color valves 26 , 27 via a paint supply pump (not shown).
, 28 and 29. These color bulbs 26
, 27 , 28 , and 29 are controlled by an output signal from a control device 30 . When any one of the color valves 26, 27, 28, 29 is opened by the output signal of the control device 30, the paint is transferred to the corresponding paint tank 22゜2.
The liquid is ejected from the nozzle port 9 through the open collar valves 3, 24, and 25.

On the other hand, the shaving air supply hole 12 of the shaving air chamber 11 is connected to the shaving air supply conduit 31 .

This shaving air supply conduit 31 is branched into four shaving air supply branch pipes 32 , 33 , 34 , 35 , and each of these shaving air supply branch pipes 32 , 3
3 , 34 , 35 are connected to a common compressed air source 36 . Each shaving air supply branch pipe 32 , 33 , 3
4 and 35 have pressure regulating valves A, B, C, and D for regulating the shaving air pressure, respectively, and shaving air branch passages 32 and 35, respectively.
An on-off valve 37 that controls the opening and closing of 33, 34, and 35.
, 38, 39, and 40 are arranged. Each on-off valve 37
38, 39, 40 are controlled by the pilot air pressure in pilot air chambers 41, 42, 43, 44 provided for them, respectively.

43 and 44 are respectively corresponding pilot air supply conduits 4
5゜46, 47, 48 and electromagnetic on/off valves 49, 5
0 , 51 , 52 to a common compressed air source 53 . Separate each one of these valves 49, 50, 5
1 and 52 are controlled by the output signal of the control device 30. When any one of the electromagnetic on-off valves 49 , 50 , 51 , 52 is opened based on the output signal of the control device 30 , the pilot air chambers 41 , 42 , 43 , 44 of the corresponding on-off valves 37 , 39 , 40 are opened. Pilot air is supplied to the As a result, any one of the on-off valves 37, 38, 39, 4 to which pilot air was supplied
0 is opened, and the corresponding pressure regulating valve A.

Shaving air whose pressure is regulated by B, C, and D is ejected from the shaving air ejection hole 13.

In the present invention, firstly, the shaving air pressure is determined by the surface area and surface shape of the object to be coated, and secondly, the shaving air pressure is determined by the paint to be applied. First, we will explain the shaving air pressure, which is determined by the surface area and surface shape of the object to be painted.

FIG. 3 shows the case where the side outer panels of the vehicle body are painted. The painting operation begins when the spray head, which is disposed opposite the side skin of the vehicle body, reaches the device 1 shown in FIG. 3. The shaving air pressure is maintained constant between positions ■ and ■. Next, when the position H is reached, the shaving air pressure is controlled according to the type of vehicle, and the shaving air pressure is maintained constant between positions (2) and (2).

Hereinafter, shaving air pressures depending on the vehicle type are indicated by H (high pressure) and L (low pressure).

As shown in the table above, when the vehicle type reaches position I, if the vehicle type is I'lhl, the shaving air pressure is H (high pressure), and if the vehicle type is N.
12, the shaving air pressure is set to L (low pressure). Below, the shaving air pressure when the position..., III... is reached is as shown in the table above. H and L in the above table are determined by the surface area of the part of the vehicle body to be painted and the surface shape of the part to be painted. However, even if the surface area and surface shape of the part to be painted are the same, if the paint is changed, the spread angle of the sprayed paint will change due to differences in paint viscosity, etc., and if the spread angle becomes large, local When the paint film becomes thin (and the spread angle becomes small), a large amount of paint is applied locally, causing so-called sagging.Therefore, in the present invention, the surface area of the part to be painted, the surface In addition to the shape, the shaving air pressure is controlled taking into consideration the properties of the paint.

Two methods of controlling shaving air pressure that take into account the properties of paint will be described below.

The first method is to first determine whether the shaving air pressure is H or not depending on the car model, and then use the pressure regulating valves A, B, C, and D to be used directly depending on the paint for H and L. This is a method of determining

An example of the shaving air pressure settings for pressure regulating valves A, B, C, and D in this case is shown in the table below.

Next, pressure regulating valves A, B, C, and D to be selected for H and L are determined as shown in the table below depending on the type of paint.

Therefore, if the car type is No. 1 and paint of No. 1 is used, the pressure regulating valves used in sequence at positions I to ■ are A, A,
B, A, A, B. On the other hand, the car model is 障2 and magnetic 2.
When using paint, pressure regulating valves C and A are used sequentially at positions ■ to ■.

C, A, C, C.

The second method is to predetermine a group of pressure regulating valves to be used for paint, and select pressure regulating valves A and B from the pressure regulating valve group for H and L, which are determined depending on the vehicle type.

This is a method to determine C and D.

An example of the shaving air pressure settings for pressure regulating valves A, B, C, and D in this case is shown in the table below.

Next, the pressure regulating valve groups determined according to the type of paint are as follows.

The pressure regulating valve is selected as follows depending on the vehicle type and paint.

Therefore, when the car type is 1 and floor 1 paint is used, the pressure regulating valves used in sequence at positions I to ■ are A, A,
B, A, A, B.

On the other hand, if the car model is N12 and N12 paint is used, the pressure regulating valves are used sequentially at positions ■ to ■.
C, D, C, D, D.

In addition, in the embodiments described so far, the shaving air pressure depending on the vehicle type is H (high pressure) and L (low pressure).
We have explained the case where the shaving air pressure is adjusted in four stages, but the shaving air pressure is set to three or more stages of H (high pressure), M (medium pressure), and L (low pressure), and the shaving air pressure is The number of pressure regulating stages can also be six or more.

〔Effect of the invention〕

In addition to controlling the shaving air pressure according to the surface area and shape of the object to be coated, controlling the shaving air pressure according to the paint type makes it possible to ensure coating with a uniform film thickness without sagging.

[Brief explanation of drawings]

FIG. 1 is an overall view of the coating apparatus, FIG. 2 is an enlarged side sectional view of a part of the rotary atomizing electrostatic coating apparatus, and FIG. 3 is a side view of a vehicle body. DESCRIPTION OF SYMBOLS 1...Rotary atomizing sieve 1 is connected to the coating apparatus main body, 3...Spray head, 13...Shaving air outlet, 31...Shaving air supply conduit, 32, 33
, 34, 35... Shaving air supply branch pipe, 3
7, 3B, 39, 40... On-off valve, A, B,
C, D...pressure regulating valve.

Claims (1)

[Claims] A rotary atomizing electrostatic coating device that ejects shaving air from behind a spray head that rotates at high speed, passing around the outer circumferential surface of the spray head toward the front, and controlling the spread angle of paint spray using the shaving air. A coating method using a rotary atomizing electrostatic coating device in which the shaving air pressure is controlled according to the surface area and shape of the object to be coated and the type of paint to be coated.