JP7685156B2 - Device and method for preventing secondary dripping of electrodeposition paint - Google Patents

Description

The present invention relates to a device and method for preventing secondary dripping of electrocoating paint.

In the electrodeposition painting process, the electrodeposition-painted car body is washed with water, and then transported to a drying oven for drying and baking. During the drying and baking process, the rise in body temperature can cause secondary dripping, where the electrodeposition paint and washing water remaining in the gaps in the car body flow out. If the electrodeposition paint that flows out due to the secondary dripping adheres to the paint film on the car body, the quality of the finished paint will decrease.

As a device for preventing secondary dripping of electrocoat paint, a robot for preventing secondary dripping is known that sprays air onto a workpiece to remove dripping of electrocoat paint before the electrocoat-coated workpiece is baked (see, for example, Patent Document 1). In this device, the air nozzle of the robot for preventing secondary dripping is positioned at an injection position where air can be injected toward the inside of the workpiece, where the steel plate is bag-shaped.

Patent No. 4769259

In a device that sprays air as described in Patent Document 1 above, there is a risk that the electrodeposition paint remaining in the gaps between the panels that make up the body may not be sufficiently removed. The object of the present invention is to provide a device and method for preventing secondary dripping of electrodeposition paint that can reliably prevent secondary dripping of the electrodeposition paint on the vehicle body after electrodeposition painting.

According to one aspect of the present invention, a secondary sagging prevention device for electrodeposition paint on a vehicle body after electrodeposition coating is provided, which includes a robot having an arm. This secondary sagging prevention device for electrodeposition paint includes a vibration unit attached to the tip of the arm, and a control unit that moves the arm so that the vibration unit contacts a preset vibration point on the vehicle body after electrodeposition coating, and controls the arm and the vibration unit so that the vibration unit vibrates the vibration point.

According to another aspect of the present invention, there is provided a method for preventing secondary dripping of electrocoat paint on a vehicle body after electrocoat painting using a robot having an arm. This method for preventing secondary dripping of electrocoat paint involves moving the arm so that a vibration unit attached to the tip of the arm comes into contact with a preset vibration point on the vehicle body after electrocoat painting, and vibrating the vibration point with the vibration unit.

According to the present invention, it is possible to reliably prevent secondary dripping of the electrocoat paint on the vehicle body after electrocoat painting.

3 is a flowchart illustrating a flow of a painting process in one embodiment of the present invention. FIG. 1 is a diagram for explaining prevention of secondary sagging of electrodeposition paint. FIG. 1 is a diagram showing a schematic configuration of a secondary drip prevention device according to an embodiment of the present invention. 4 is a diagram showing a configuration of a vibration unit shown in FIG. 3. 4 is a flowchart illustrating a flow of a secondary sagging prevention method according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of vibration excitation points on a vehicle body.

The secondary drip prevention device and method for electrodeposition paint according to one embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 is a flow chart explaining the flow of the painting process in one embodiment of the present invention.

The car body completed through the pressing and welding processes is transported to the painting process for painting. As shown in FIG. 1, in the painting process, in step S1, a process for removing dust and oil is carried out as a pre-treatment for painting, and then in step S2, electrocoating is carried out to enhance the rust-prevention effect of the car body. The electrocoated car body is drained and dried in step S3, and then further processing such as a middle coat process and a top coat process (not shown) is carried out.

Each process will be explained below. First, the pre-processing in step S1 involves hot water washing (S11), degreasing (S12), water washing (S13), surface treatment (S14), chemical conversion treatment (S15), and water washing (S16), which are carried out in that order. The pre-processing carried out here is a common process in the painting process, so a detailed explanation will be omitted.

In the electrodeposition coating step S2, the vehicle body is immersed in a tank containing water-based electrodeposition paint, and an electrodeposition process is carried out to form a coating of electrodeposition paint on the vehicle body surface (S21). In the electrodeposition process, the electrodeposition paint in the tank is usually made positive and the vehicle body is made negative, and an electric current is passed through it to deposit the electrodeposition paint on the vehicle body and paint it. This allows the electrodeposition paint to reach even the smallest of places, so that the vehicle body is painted evenly. After that, a water washing process is carried out to wash the vehicle body with washing water after the coating has been formed on it (S22).

In the draining and drying step S3, a draining process is performed (S31) to remove the electrodeposition paint and washing water remaining on the vehicle body after the water washing process (S22) by air blowing. As described above, since the electrodeposition paint can penetrate into small spaces on the vehicle body, even if the above-mentioned water washing process (S22) and water draining process (S31) are performed, there is a possibility that some of the electrodeposition paint may not be removed and may remain in the gaps of the vehicle body. If the electrodeposition paint and washing water (hereinafter sometimes referred to as residual paint) remaining in the gaps of the vehicle body are heated in the drying oven and flow out of the gaps, a secondary dripping phenomenon occurs, which reduces the quality of the finished paint.

Therefore, in one embodiment of the present invention, after the water draining process (S31), and before the vehicle body is transported to a drying oven to perform the drying and baking process of the electrocoating paint (S33), a water draining and vibration process is performed to remove the residual paint remaining in the gaps in the vehicle body by localized and direct vibration (S32). After the water draining and vibration process, the vehicle body is transported to a drying oven to perform the drying and baking process of the electrocoating paint (S33). In this way, secondary dripping is prevented by forcibly removing the residual paint remaining before the drying and baking process (S33) by using vibration.

2(a) and (b) are diagrams for explaining the prevention of secondary dripping of the electrodeposition paint. In the vehicle body, there are various mating surfaces where multiple vehicle body panels P are overlapped. Here, the mating surface refers to a portion where two or more vehicle body panels P overlap in the plate thickness direction of the panel. In Figs. 2(a) and (b), a first vehicle body panel 1 and a second vehicle body panel 2, each of which corresponds to a vehicle body panel P, are overlapped to form a mating surface 4. As shown in Fig. 2(a), if the first vehicle body panel 1 and the second vehicle body panel 2 are not completely in contact with each other at the mating surface 4 and a gap 3 exists between the first vehicle body panel 1 and the second vehicle body panel 2, the electrodeposition paint and washing water may remain in the gap 3. If the first panel 1 and the second panel 2 are formed from automotive steel plates having a plate thickness of, for example, 0.65 mm, the length of the gap 3 in the plate thickness direction is, for example, about 1 mm. If electrocoating paint gets into such a tiny gap, it will remain in the gap due to its viscosity and surface tension, making it difficult to remove even by blowing air into it with an air blower.

In this embodiment, as shown in FIG. 2(b), the mating surface 4 where the first panel 1 and the second panel 2 are overlapped is locally and directly vibrated to forcibly expel the electrodeposition paint and washing water remaining in the gap 3 of the mating surface 4. Note that this embodiment can also be applied to expel residual paint remaining in gaps and recesses of the vehicle body other than the mating surface 4.

The schematic configuration of the secondary drip prevention device 100 for electrodeposition paint in this embodiment will be described below with reference to FIG. 3. The secondary drip prevention device 100 prevents secondary dripping by performing the above-mentioned drainage vibration process on the vehicle body 300 transported along the transport rail by the transport hanger 200. During the drainage vibration process, the transport hanger 200 is fixed with a stopper, a hanger vibration prevention guide, etc. to prevent the vehicle body 300 from swinging.

The secondary sagging prevention device 100 includes a robot 10, a vibration unit 30 attached to the tip of the arm of the robot 10, and a control unit 50 that controls the operation of the robot 10 and the vibration of the vibration unit 30.

The robot 10 is a multi-joint robot having a fixed base 11, a first arm 12 (arm) rotatably attached to the base 11, and a second arm 13 (arm) rotatably attached to the first arm 12. A vibration unit 30 and a spray nozzle 40 that sprays washing water are attached to the tip of the second arm 13 of the robot 10.

Figure 4 shows the configuration of the vibration unit 30 attached to the robot 10. The vibration unit 30 includes a contact portion 31 that contacts the vehicle body, a vibrator 32 that vibrates the contact portion 31, and a force sensor 33 that detects that the contact portion 31 has contacted the vehicle body. The vibration unit 30 is attached to the tip of the second arm 13 of the robot 10 via a robot arm attachment base 34. The contact portion 31 is made of an elastic material such as an elastomer, and the tip portion that contacts the vehicle body 300 is formed in a curved shape. By making the contact portion 31 a curved shape made of an elastic material, it is possible to prevent the electrocoating film formed on the vehicle body 300 from being damaged when the contact portion 31 is brought into contact with the vehicle body 300 and vibrated. The contact portion 31 is connected to the vibrator 32 via a body attachment 35.

The vibrator 32 has, for example, an eccentric motor, and vibrates the contact portion 31 in response to instructions from the control portion 50. The vibration conditions of the vibrator 32, such as the amplitude, acceleration, and frequency, are controlled in response to instructions from the control portion 50. The vibrator 32 is connected to the robot arm mounting base 34 via anti-vibration rubber 36 to prevent the vibration from being transmitted to the robot 10.

The force sensor 33 is configured to detect, for example, force components in three axial directions and moment components in three axial directions, and detects the pressing force when the second arm 13 presses the contact portion 31 against the vehicle body. The detection result of the force sensor 33 is sent to the control unit 50. By detecting the pressing force, the control unit 50 can detect that the contact portion 31 has come into contact with the vehicle body, and can control the degree of force with which the contact portion 31 is pressed against the vehicle body.

The control unit 50 includes, for example, a processor, and is configured to control the overall operation of the secondary drip prevention device 100 according to a predetermined operating program. The control unit 50 may be provided inside the robot 10, or may be installed as an external device to the robot 10.

Next, the flow of the secondary drip prevention method executed by the secondary drip prevention device 100 will be explained with reference to the flowchart in FIG. 5.

In step S102, the control unit 50 moves the first arm 12 and the second arm 13 of the robot 10 to bring the vibration unit 30 close to the desired vibration location on the vehicle body, for example the mating surface 4 described above, and abuts the contact portion 31 of the vibration unit 30 against the vibration location. In step S104, the control unit 50 detects that the contact portion 31 of the vibration unit 30 is abutting against the vibration location on the vehicle body with a predetermined pressing force based on the detection result of the force sensor 33. In step S106, the control unit 50 controls the vibrator 32 so that the contact portion 31 of the vibration unit 30 vibrates according to predetermined vibration conditions while abutting against the vehicle body. As a result, residual paint remaining in the gaps in the vehicle body is expelled from the gaps by local and direct vibration.

Here, the vibration conditions when vibrating the vibration points of the vehicle body using the vibration unit 30 include the vibration application time, vibration frequency, vibration direction, amplitude, strength, etc. These vibration conditions are adjusted appropriately for each vibration point to be vibrated so that the remaining paint can be reliably discharged. The vibration direction is preferably parallel to the thickness direction of the vehicle body panel at the vibration point. A direction parallel to the thickness direction of the vehicle body panel is a direction approximately perpendicular to the surface of the vehicle body panel. By applying vibration in the thickness direction of the vehicle body panel, the remaining paint can be effectively pushed out of the gaps and flowed downward in the vertical direction of the vehicle.

In step S108, the control unit 50 controls the spray nozzle 40 attached to the tip of the second arm 13 to spray washing water to wash away the residual paint discharged from the gap. The above operation is performed for each vibration point.

The operation of the above-mentioned secondary drip prevention method may be taught in advance to the control unit 50 of the secondary drip prevention device 100 using a teaching device (not shown), and the operation of the secondary drip prevention device 100 may be automatically controlled according to the taught operating program.

Figure 6 shows examples of locations on the vehicle body that are vibrated by the vibration unit 30. Figures 6(a) and (b) are schematic diagrams of the vehicle body of a cab-over vehicle after electrocoating, as viewed from the rear and right side of the vehicle. The vibration locations are locations where electrocoating paint and washing water are likely to remain, such as mating surfaces between vehicle body panels and gaps in hinges, and are set at locations where the remaining paint can be expelled from the gaps by vibrating the vibration locations with the vibration unit 30.

As shown in Figs. 6(a) and (b), the cab-over type vehicle 80 has, for example, four vibration points. The cab-over type vehicle 80 has a cabin section 81 and a deck section 82. The deck section 82 has a deck floor panel 83 forming the lower surface, a rear gate panel 84 (vehicle body panel) forming the rear surface, and the like. The lower end of the rear gate panel 84 in the vertical direction of the vehicle is rotatably attached to the deck floor panel 83 toward the rear side of the vehicle by three rear gate hinges 85. The cabin section 81 has a cabin back upper panel 86 (first vehicle body panel) forming the rear surface, a cabin back lower panel 87 (second vehicle body panel), and the like. The cabin back upper panel 86 and the cabin back lower panel 87 are joined to each other by, for example, spot welding.

The rear gate hinge 85 has a gap in which the electrocoating paint and washing water are likely to remain. Furthermore, if secondary dripping occurs from the rear gate hinge 85, the quality of the paint finish on the rear surface of the deck section 82 will be reduced. Therefore, in order to prevent secondary dripping from the rear gate hinge 85, a vibration point 61 is set in the upper region of the rear gate panel 84, which corresponds to the upper side of the rear gate hinge 85 in the vertical direction of the vehicle. Here, one vibration point 61 is set for each rear gate hinge 85, so three vibration points 61 are set on the rear gate panel 84. The vibration points 61 are vibrated in the plate thickness direction of the rear gate panel 84 from the rear side of the vehicle by the vibration unit 30.

The cabin back upper panel 86 is disposed on the inside of the vehicle compartment above the cabin back lower panel 87 in the vertical direction of the vehicle, and the cabin back lower panel 87 is disposed on the outside of the vehicle compartment below the cabin back upper panel 86 in the vertical direction of the vehicle. If secondary dripping occurs from the mating surface between the cabin back upper panel 86 and the cabin back lower panel 87, the quality of the paint finish on the rear part of the cabin section 81 will be reduced. Therefore, in order to prevent secondary dripping from the mating surface between the cabin back upper panel 86 and the cabin back lower panel 87, one vibration point 62 is set in an area corresponding to the gap between the mating surfaces of the cabin back upper panel 86. The vibration point 62 is vibrated in the plate thickness direction of the cabin back upper panel 86 by the vibration unit 30 from the inside of the cabin section 81.

Incidentally, since the mating surface of the cabin back upper panel 86 and the cabin back lower panel 87 has a certain length in the vehicle width direction, multiple vibration points 62 may be provided in the area corresponding to the mating surface. However, by setting one vibration point at an appropriate position midway between multiple parts of the mating surface of the cabin back upper panel 86 and the cabin back lower panel 87 where electrocoating paint and washing water are likely to remain, the residual paint remaining in multiple parts can be removed all at once with a single vibration. This can shorten the work time required to prevent secondary dripping.

Although not shown in the figure, in the case of a minivan, for example, four vibration points are set. A minivan is provided with sliding doors on both the left and right side surfaces that slide in the front-to-rear direction of the vehicle. A door inner panel is disposed on the interior side of the sliding door, and a door latch is attached to the exterior side of the door inner panel. Therefore, in order to prevent secondary sagging from the gap in the mating surface where the door latch is attached to the door inner panel, a vibration point is set in an area of the door inner panel that corresponds to the gap in the mating surface with the door latch, for example. This vibration point is vibrated in the thickness direction of the door inner panel from the inside of the passenger compartment by the vibration unit 30.

A rear quarter panel is disposed at the rear of the side body of a one-box vehicle in the vehicle front-rear direction. A rear quarter inner upper panel (first vehicle body panel) and a rear quarter inner lower panel (second vehicle body panel) are disposed on the passenger compartment side of the rear quarter panel. The rear quarter inner upper panel is disposed on the upper side of the rear quarter inner lower panel in the vehicle vertical direction and on the inside of the passenger compartment, and the rear quarter inner lower panel is disposed on the lower side of the rear quarter inner upper panel in the vehicle vertical direction and on the outside of the passenger compartment. The rear quarter inner upper panel and the rear quarter inner lower panel are joined to each other by, for example, spot welding. Therefore, in order to prevent secondary sagging from the mating surfaces of the rear quarter inner upper panel and the rear quarter inner lower panel, a vibration point is set, for example, in an area corresponding to the gap between the mating surfaces of the rear quarter inner upper panel. This vibration point is vibrated in the plate thickness direction of the rear quarter inner upper panel by the vibration unit 30.

The secondary drip prevention device 100 for electrodeposition paint according to the present embodiment described above can achieve the following effects:

The secondary drip prevention device 100 for electrodeposition paint is equipped with a vibration unit 30 attached to the tip of the second arm 13 of the robot 10, and a control unit 50 that controls the first arm 12 and the second arm 13 and the vibration unit 30 so that the vibration unit 30 contacts a preset vibration point on the vehicle body 300 after electrodeposition painting, and vibrates the vibration point with the vibration unit 30. This allows pinpoint vibration to be applied to parts of the vehicle body 300 after electrodeposition painting where electrodeposition paint is likely to remain, effectively removing residual paint from gaps in the vehicle body 300 and preventing secondary dripping. Depending on the position of the vibration point, such as the vibration point 61 of the rear gate panel 84, the vibration unit 30 can be approached from the outside of the vehicle body 300, so that the work time can be shortened compared to when work is performed from inside the vehicle interior through an opening in the vehicle body 300. In addition, because the vibration is transmitted through the vehicle body panels, even if the position where the contact part 31 of the vibrating part 30 contacts the vehicle body is slightly shifted from the preset vibration point due to the accuracy of the vehicle body, outside temperature, humidity, etc., there is no significant impact on the effect of removing residual paint by vibration. This leads to improved operability and maintainability of the secondary drip prevention device 100 for electrodeposition paint.

The vibration unit 30 is made of an elastic material and has a contact unit 31 formed in a curved shape at the portion that contacts the vehicle body 300, and a vibrator 32 that vibrates the contact unit 31. As a result, even if the contact unit 31 is vibrated while in contact with the vehicle body 300, painting defects such as chipping of the paint on the vehicle body 300 do not occur.

The vibration points include vibration points set on the vehicle body panel P of the vehicle body 300. The control unit 50 is configured to vibrate the vibration unit 30 in the thickness direction of the vehicle body panel P at the vibration points of the vehicle body 300. This makes it possible to reliably expel residual paint from gaps in the vehicle body 300.

The vehicle body panel P of the vehicle body 300 includes a first vehicle body panel 1 and a second vehicle body panel 2, and the vibration points are set in an area corresponding to the gap 3 in the mating surface portion 4 where the first vehicle body panel 1 and the second vehicle body panel 2 are overlapped. Since electrocoating paint and washing water tend to remain in the mating surface portion where multiple vehicle body panels overlap in the thickness direction, by setting the vibration points in an area corresponding to the mating surface portion, the remaining paint can be effectively expelled from the gap in the vehicle body.

In particular, when the first body panel 1 is disposed above the second body panel 2 in the vertical direction of the vehicle and on the inside of the vehicle cabin, and the second body panel 2 is disposed below the first body panel 1 in the vertical direction of the vehicle and on the outside of the vehicle cabin, the vibration location is set in an area corresponding to the gap in the mating surface portion 4 of the first body panel 1, so that the remaining paint can be more reliably discharged from the gap in the vehicle body.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications and changes are possible based on the technical concept of the present invention.

For example, the vibration points by the vibration unit 30 are not limited to those shown in FIG. 6, and it is possible to set vibration points at locations other than those shown in FIG. 6 as long as the residual paint that has entered the gap due to the vibration of the vibration unit 30 can be discharged. The number of vibration points is also not limited to the above-mentioned embodiment. For example, in the above-mentioned embodiment, three vibration points 61 are set on the rear gate panel 84, but this may be reduced to two. Specifically, instead of setting three vibration points 61 on the left, center, and right sides of the vehicle in the left-right direction, one vibration point can be set at an appropriate position halfway between the left vibration point 61 and the center vibration point 61 in the left-right direction of the vehicle, and one vibration point can be set at an appropriate position halfway between the center vibration point 61 and the right vibration point 61. In this way, by setting one vibration point at an appropriate position halfway between multiple parts where the electrodeposition paint and the washing water are likely to remain, the residual paint remaining in multiple parts can be removed all at once by one vibration. This makes it possible to shorten the work time required to prevent secondary dripping.

The vibration point may be set at a location other than the vehicle body panel, such as the rear gate panel 84 or the cabin back upper panel 86 described above. For example, the vibration point may be set at the rear gate hinge 85, and the rear gate hinge 85 may be directly vibrated to prevent secondary sagging from the rear gate hinge 85. It is preferable to set the vibration point away from the spot welding position. This is because the two panels are in close contact at the mating surface at the spot welding position, and no gaps are created.

In the above-described embodiment, the vibration unit 30 and the spray nozzle 40 for spraying rinsing water are attached to the tip of the second arm 13 of the robot 10, but the present invention is not limited to this. Instead of spraying rinsing water from the spray nozzle 40, air may be sprayed. Also, the spray nozzle 40 may be attached to the arm of a robot other than the robot 10 to which the vibration unit 30 is attached. It is also possible to omit the water washing process (S108) after vibration by the vibration unit 30.

In the above-described embodiment, the transport hanger 200 is fixed with a stopper, a hanger anti-vibration guide, etc. to prevent the vehicle body 300 from swinging during the water-draining vibration treatment, but the water-draining vibration treatment may be performed while the vehicle body 300 is being transported by the transport hanger 200. In this case, a robot travel rail is installed that extends in a direction parallel to the transport direction of the transport hanger 200, and the robot 10 moves along the robot travel rail in accordance with the movement of the vehicle body 300.

Although one robot 10 is shown in FIG. 3, multiple robots may be used to perform the water-draining vibration process.

The configuration of the vibration section 30 is not limited to that shown in FIG. 4. In addition, the vibration direction of the vibration section 30 is not limited to the thickness direction of the vehicle body panel, and it may vibrate in a direction different from the thickness direction. The material and shape of the contact section 31 are also not limited to an elastic material and a curved shape, and any material and shape may be used as long as they do not damage the coating of the electrocoating paint formed on the vehicle body.

1 First vehicle body panel 2 Second vehicle body panel 3 Gap 4 Mating surface portion 10 Robot 12 First arm (arm)
13 Second arm (arm)
30 Vibration portion 31 Contact portion 32 Vibrator 50 Control portion 61, 62 Vibration location 86 Cabin back upper panel (first vehicle body panel)
87 Cabin back lower panel (second body panel)
100 Secondary drip prevention device 300 Vehicle body

Claims (7)

A secondary drip prevention device for electrodeposition paint on a vehicle body after electrodeposition coating, comprising a robot having an arm,
A vibration unit attached to a tip of the arm;
a control unit that controls the arm and the vibration unit so that the vibration unit contacts a preset vibration point on the vehicle body after electrocoating, and vibrates the vibration point with the vibration unit, The vibration unit includes:
a contact portion made of an elastic material, the portion contacting the vehicle body being formed into a curved shape;
The secondary sagging prevention device for electrodeposition paint according to claim 1, further comprising a vibrator for vibrating the contact portion. The secondary sagging prevention device for electrodeposition paint according to claim 1 or 2, wherein the vibration application points include vibration application points set on a vehicle body panel of the vehicle body. The device for preventing secondary sagging of electrodeposition paint according to claim 3 , wherein the control unit is configured to vibrate the vibration unit in the plate thickness direction of the vehicle body panel at the vibration application location of the vehicle body panel. the vehicle body panels include a first vehicle body panel and a second vehicle body panel;
The secondary drip prevention device for electrodeposition paint according to claim 3 or 4, wherein the vibration application location is set in an area corresponding to a gap between the mating surfaces of the first vehicle body panel and the second vehicle body panel. the first vehicle body panel is disposed on an upper side of the second vehicle body panel in a vehicle vertical direction and on an inner side of the vehicle compartment, and the second vehicle body panel is disposed on a lower side of the first vehicle body panel in the vehicle vertical direction and on an outer side of the vehicle compartment,
The device for preventing secondary sagging of electrodeposition paint according to claim 5 , wherein the vibration application location is set in an area corresponding to a gap in the mating surface portion of the first vehicle body panel. A method for preventing secondary sagging of electrodeposition paint on a vehicle body after electrodeposition painting by a robot having an arm, comprising:
The arm is moved so that a vibration unit attached to a tip of the arm comes into contact with a preset vibration location on a vehicle body after electrocoating;
A method for preventing secondary sagging of electrodeposition paint, comprising vibrating the vibration location with the vibration unit.

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