JPS5921670B2 - Vehicle body - How to paint the outer panel - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for painting vehicle body outer panels.

A conventional coating device for painting the side outer panels of a vehicle body is, for example, as shown in FIG. 1, a pair of rotary atomizing electrostatic coating devices 1, which are moved from side to side in order to paint the roof of the vehicle body. 2, and a pair of left and right rotary atomizing electrostatic coating devices 3, 4, )-5, 6 fixedly arranged for painting the side outer panels of the vehicle body.

The vehicle body 7 is transported at a constant speed by a transport device 8, and during this time each rotary atomizing electrostatic coating device 1, 2, 3, 4, 5
, 6 spray heads 1a, 2a, 3a, 4a, 5a, 6a toward the outer panel of the vehicle body. The outer plate 9 on one side of the body is usually narrower in width at the front and rear wheels, and therefore, when painting this outer plate on one side of the body, the paint spraying action from the rotary atomizing electrostatic coating devices 4 and 6 is applied. The spray head 3a, 5 of the rotary atomizing electrostatic coating device 3, 5 is stopped.
The paint is sprayed only from a. However, in such a coating device, the paint spraying action from the lower rotary atomizing electrostatic coating devices 4 and 6 is simply stopped depending on the shape of the body-side outer panel, so the paint spray pattern is consistent with the body. It does not follow the shape of the side skin sufficiently, and as a result, the paint film layer becomes uneven, the color varies depending on the location, or there is too much paint on the bottom edge of the side skin. Problems such as drop-shaped paint buildup may occur in the area. In particular, when a metallic paint containing aluminum powder is used as the paint, such problems become more pronounced. SUMMARY OF THE INVENTION An object of the present invention is to provide a method of painting an outer panel of a vehicle body that can obtain a uniform painted surface of the outer panel of one side of a vehicle body.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 3, 20 is a vehicle body 1, 21 is a conveying device for conveying the vehicle body 20 at a constant speed;
Reference numerals 22, 23, 24, and 25 indicate rotary atomizing electrostatic coating devices mounted on a portal frame 26, respectively. The rotary atomizing electrostatic coating devices 22 and 25 are attached to one side outer plate 26 and 27 of the body, respectively.
The rotary atomizing electrostatic coating devices 23 and 24 are equipped with spray heads 22a and 25a for spraying paint toward outer panels 26 and 27 on one side of the body.
The spray heads 23a and 24a are provided for spraying paint onto the roof 28 in order to paint the roof 28. These rotary atomizing electrostatic coating devices 23 and 24 have a slider 2 supported so as to be slidable in the horizontal direction on a frame 26.
9, and this slider 29 is swung left and right by a drive motor 31 via a crank 30. On the other hand, the rotary atomizing electrostatic coating devices 22 and 25 have a slider 32 supported vertically slidably on the frame 26.
, 33, respectively, and these sliders 32, 33 are connected to the drive motor 3 via corresponding blanks 34, 35, respectively.
6 and 37 to move it up and down. Each rotary atomizing electrostatic coating device 22, 23, 24, 25 has the same structure, therefore, referring to FIG.
Only structure 2 will be explained. Referring to Figure 2,
Rotary atomization electrostatic coating: A spray head 22a is screwed onto the tip of a rotating shaft 41 rotatably supported within the housing 42. The rotating shaft 41 is connected to a high voltage generator 43 that can selectively generate a negative high voltage from -60 KV to -120 KV, and therefore, a negative high voltage is applied to the spray head 22a via the rotating shaft 41. be done. As shown in FIG. 2, the spray head 22a has a cup-shaped inner peripheral surface 44 and an annular space 45 formed around the rotating shaft 41, and a nozzle rod 47 of the paint injection nozzle 46 is disposed within this annular space 45. Ru. Furthermore,
A large number of paint outlet holes 48 are formed at the innermost part of the annular space 45 over the entire circumference thereof. The paint injection nozzle 46 is connected to a paint supply pump 50 via a paint supply conduit 49, in which a paint supply cutoff valve 51 and a paint supply control valve 52 are provided. On the other hand, an annular air chamber 53 is formed around the rotating shaft 41, and this annular air chamber 53 has a large number of air ejection holes 54. The annular air chamber 53 is connected to a compressed air source 56 via an air supply conduit 55 in which an air supply control valve 57 is provided.
A rotational force is applied to the rotary shaft 41 by an air turbine 58 shown diagrammatically, and a turbine nozzle (not shown) that blows out compressed air toward the turbine blades of the plate air turbine 58 is connected to the rotary shaft 41 via an air supply control valve 59. and is connected to a compressed air source 60. When painting, first, the rotating shaft 41 is rotated by the turbine 58, and a negative high voltage is applied to the spray head 22a via the rotating shaft 41. Next, paint is supplied from the nozzle 47 of the paint injection nozzle 46, and air is jetted from the air jet hole 54 of the annular air chamber 53. The paint supplied from nozzle no. 47 is sprayed from spray head 2.
The centrifugal force generated by the rotation of the paint outlet hole 48
The water flows out through the cup-shaped inner circumferential surface 44. Next, this paint spreads as a thin liquid film on the cup-shaped inner circumferential surface 44 and reaches the tip of the spray head 22a, and then a paint spray is released from the tip of the spray head 22a as shown by the broken line A. As described above, a high negative voltage is applied to the spray head 22a, and therefore the paint particles are negatively charged.
On the other hand, since the vehicle body 20 is at zero potential, the paint particles are attracted toward the vehicle body 20 by the electric force, thereby painting the vehicle body 20. The air ejected from the air ejection holes 54 of the annular air chamber 53 moves forward in a manner that envelops the paint spray A, as shown by arrow B, and controls the spread angle of the paint spray A. On the other hand, in FIG. 4, a vehicle body 20 to be painted is moved in the direction of arrow C by a conveying device 21 (FIG. 3), and the path through which this vehicle body 20 passes is narrowed to include, for example, a light source 58 and a photoelectric switch. 59 are arranged.

The photoelectric switch 59 issues a painting start signal indicating that the vehicle body 20 has reached the position where painting should begin when the vehicle body 20 shuts off the light emitted from the light source 58.
FIG. 5 shows electronic control unit 70. FIG.

As shown in FIG. 5, the electronic control unit 70 is composed of, for example, a digital computer, and has a microprocessor (MPU) 71 that performs various calculation processes, a random access memory (RAM) 72, control programs, calculation constants, etc. stored in advance. read-only memory (ROM) 73
, input port 74 and output port 75 are bidirectional bus 7
They are connected to each other via 6. Furthermore, a clock generator 77 is provided within the electronic control unit 70 for generating various clock signals. As shown in FIG. 5, the coating start signal emitted from the photoelectric switch 59
It is also read into the MPU 7l via the bus 76.
When a coating start signal is generated from the photoelectric switch 59, the paint supply cutoff valve 51 and the paint supply control valve 5 are connected to the output port 75 according to a program stored in advance in the ROM 73.
2. Drive data for driving the air supply control valve 59, high voltage generator 43, air supply control valve 57, and motor drive circuit 60 are written. The paint supply cutoff valve 51 controls the start and stop of supply of paint sprayed from the paint injection nozzle 46 based on drive data written to the output port 75. The paint supply control valve 52 switches the paint supply amount to three levels: large, medium, and small based on the drive data written to the output port 75. The air supply control valve 59 controls the amount of air supplied to the turbine 58 based on the drive data written to the output port 75 to increase the rotation speed of the rotating shaft 41.
Switch to 3 levels: medium and low. The high voltage generator 43 generates a spray head 2 based on the drive data written to the output port 75.
The negative high voltage applied to 2a is switched to two levels: high and low. The air supply control valve 57 controls the air injection hole 54 of the annular air chamber 53 based on the drive data written to the output port 75.
Controls the amount of air injected into two levels: large and small. The motor drive circuit 60 controls rotation and stopping of the motors 36 and 37 based on drive data written to the output port 75. Next, the operation of the coating apparatus according to the present invention will be explained with reference to the time chart shown in FIG.

In FIG. 4, a side outer plate 2 of a vehicle body 20 is shown.
The broken lines drawn on 6 indicate the rotary atomizing electrostatic coating devices 22, 25.
The spray directions of the spray heads 22a and 25a are shown. This injection direction is controlled by the drive motors 36 and 37 based on the output signal of the electronic control unit 70 as described above.
In addition, Q is connected to paint supply cutoff valve 1 and paint supply control valve 5.
2 indicates the paint supply amount controlled by the air supply control valve 59, N indicates the rotation speed of the rotating shaft 41 controlled by the air supply control valve 59, and V indicates the negative high voltage generated from the high voltage generator 43. , and P indicates the amount of air jetted from the air jetting hole 54 controlled by the air supply control valve 57. At time t1, when the vehicle body 20 has not yet blocked the light emitted from the light source 58, the supply of paint is stopped, as indicated by Q.

At this time, as indicated by N, the rotating shaft 41 is rotating at a low speed. Next, as shown in FIG. 4, when the time Ta at which the vehicle body 20 blocks the light emitted from the light source 58 is reached, the supply of paint is started and the rotary shaft 41 is rotated at a medium speed, as shown by V. Then, a high voltage is generated from the high voltage generator 43, and painting of the outer panel on one side of the body in front of the front wheels is started. At the same time, the drive motors 36 and 37 are driven to move the spray heads 22a and 25a up and down, and P
As shown, a small amount of air is ejected from the air ejection hole 54. Next, as shown at time T2, when the spray heads 22a, 25 reach the outer plate area on one side of the body covering the front wheels, the spray heads 22a, 25
a is stopped so that its injection direction is directed to an intermediate height position of the outer plate area on one side of the body. At this time, the paint injection amount Q, the rotation speed N of the rotating shaft 41, and the high voltage generator 43
Since the output voltage of the paint spray A is lowered and the air jet amount P from the air jet hole 54 is increased, the paint spray A
The spread angle of becomes smaller. The same thing is done when the outer plate on one side of the body covering the rear wheel is reached, as shown at time T4. As shown at time T3, when painting the outer panel on one side of the body between the front wheels and the rear wheels, the rotating shaft 41
is rotated at a high speed, a high voltage is generated from the high voltage generator 43, and a small amount of air is injected from the air jet hole 54. Further, as shown at time T5, when painting the center pillar portion, the paint injection amount Q and the output voltage of the high voltage generator 43 are reduced, and the rotating shaft 41 is rotated at a high speed. Note that at time T3, the drive motors 36 and 37 are driven to move the spray heads 22a and 25a up and down as shown by broken lines. When the painting of one side outer panel of the body covering the rear wheel is completed, as shown at time T6, the paint injection amount Q, the rotation speed of the rotating shaft 41, and the output voltage of the high voltage generator 43 are increased, and the air injection hole is increased. The amount of air ejected from 54 is reduced, and the spray heads 22a, 25a are again moved up and down.

Then, the rear end of the vehicle body 20 passes through and the painting is completed. Incidentally, the spray head fixing position at approximately the middle height of the outer plate on one side of the body that covers the front and rear wheels of the vehicle may be located above the vertically movable upper ends of other parts. As described above, according to the present invention, when the vertical movement of the rotary atomizing electrostatic coating device for painting the outer panel on one side of the body covering the front and rear wheels of the vehicle is stopped, the amount of paint sprayed on the other side of the body is This is reduced compared to the amount of paint sprayed when the rotary atomizing electrostatic coating device is moved up and down to coat the outside panels.

This is because the vehicle body, which is the object to be painted, is being transported at a constant speed, so when the vertical movement of the rotary atomizing electrostatic coating device is stopped, the amount of paint sprayed must be reduced. This is because an excessive amount of paint adheres to the top, resulting in uneven paint film thickness and drop-shaped paint buildup on the lower edge of the outer panel on one side of the body. Therefore, as mentioned above, when the vertical movement of the rotary atomizing electrostatic coating device is stopped, it is necessary to reduce the amount of paint sprayed, thereby making the coating film thickness uniform, the color uniform, and the body uniform. It is possible to prevent paint drops from forming on the lower edges of the side panels. In addition, since the vertical width of the outer panel on one side of the body that covers the front and rear wheels of the vehicle is narrow, when painting this outer panel on one side of the body, the spray angle must be made small or the spray will stick to the outer panel on one side of the body. This increases the amount of paint that escapes into the atmosphere and reduces the coating efficiency. Regarding this point, in the present invention, when painting one side outer panel part of the vehicle body, the rotation speed of the spray head is reduced, or the spray head is directed from behind the spray head along the outer periphery of the spray head toward the one side outer panel part of the vehicle body. Since the spray angle is made smaller by increasing the amount of air ejected, the coating efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is an overall view of a conventional coating device, Fig. 2 is an overall view of a rotary atomization electrostatic coating device, Fig. 3 is an overall view of a coating device according to the present invention, and Fig. 4 explains a coating method. Diagram for, 5th
The figure is a circuit diagram of the electronic control unit. 20...Vehicle body 1, 22, 23, 24, 2
5...Rotary atomization electrostatic coating device, 22a, 23a
, 24a, 25a... Spray head, 26, 27...
...Body one side outer plate, 29, 32, 33...
...Slider, 31, 36, 37... Drive motor.

Claims (1)

[Scope of Claims] 1. A painting method in which a rotary atomizing electrostatic coating device automatically paints the side outer panels of a vehicle body transported by a transport device at a predetermined constant speed, When painting the side outer panels of the body that cover the wheels, the spray head of the rotary atomizing electrostatic coating device is fixed toward the mid-height position of the side outer panels of the body, and the paint is ejected from the spray head. When painting the side outer panels of the body other than the side outer panels of the body that cover the front and rear wheels of the vehicle, the direction of the spray head should be swung up and down centering on the mid-height position of the side outer panels of the body. A method for painting an outer panel of a vehicle body in which the amount of paint sprayed from the spray head is increased. 2. In a painting method in which the side outer panels of a vehicle body that are transported by a transport device at a predetermined constant speed are automatically painted by a rotary atomizing electrostatic coating device, the side panels of the vehicle body that cover the front and rear wheels of the vehicle are When painting the exterior panels, the spray head of the rotary atomizing electrostatic coating device is fixed toward the mid-height position of the outer panel on the side of the body, and the amount of paint emitted from the spray head and the amount of paint emitted from the spray head are controlled. When painting the side outer panels of the body other than the side outer panels of the body that cover the front and rear wheels of the vehicle, reduce the rotational speed and swing the spray head up and down around the mid-height position of the side outer panels of the body. A method for painting an outer panel of a vehicle body, wherein the amount of paint sprayed from the spray head and the rotational speed of the spray head are increased. 3. In a painting method in which the side outer panels of a vehicle body that are transported by a transport device at a predetermined constant speed are automatically painted by a rotary atomizing electrostatic coating device, the side panels of the vehicle body that cover the front and rear wheels of the vehicle are When painting exterior panels, the spray head of the rotary atomizing electrostatic coating device is fixed toward the mid-height position of the exterior panel on the side of the body, and the amount of paint sprayed from the spray head is reduced. Increases the amount of air jetted from behind the spray head toward the side outer skin of the body along the outer periphery of the spray head, and when painting the side outer skin of the body other than the side outer skin of the body that covers the front and rear wheels of the vehicle, The direction of the spray head is swung up and down about the mid-height position of the side skin of the body, thereby increasing the amount of paint sprayed from the spray head and decreasing the amount of air jetted toward the side skin of the body. How to paint the exterior of a vehicle body.