Painting system and painting method using the same

Abstract

To make it possible to uniformly form a thin film and minimize a paint consumption amount in painting using an indium paint.SOLUTION: A painting system for painting a work-piece by forming an undercoat layer with an undercoat paint, then forming a middle coat layer with an indium paint, and then forming a top coat layer with a top coat paint comprises: work-piece fixing means (2) which so fixes a work-piece (W) as to be capable of freely revolving; an undercoat spray gun (7a) for spraying an undercoat paint; a middle coat spray gun (7b) for spraying an indium paint; and a top coat spray gun (7c) for spraying a top coat paint; paint supply means which supplies the paint to each spray gun; and paint filling means which fills the paint to each paint supply means. The paint supply means for supplying the indium paint is mounted on a paint robot, and the paint is sprayed to the work-piece (W) while revolving the work-piece (W).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coating system using indium paint and a coating method using the same. More specifically, the present invention relates to a coating system and a coating method using indium paint that minimize the amount of indium paint used by saving waste of the paint when applying the indium paint.

Background Art

[0002] Conventionally, there are various methods for adding value to products and increasing consumers' purchasing desire. Among them, in recent years, the method of applying a mirror-like design to products has been increasing.

[0003] For example, a mirror-like design is applied to vehicle parts such as automobile door mirrors, OA equipment, and home appliances.

[0004] By the way, as a means for imparting a mirror-like design to a product, plating and vapor deposition have been conventionally known. However, in the case of plating, there is a drawback that the environmental load is high in terms of wastewater treatment and the like.

[0005] In addition, in the case of vapor deposition, special equipment for vapor deposition is required, the equipment is large-scale and costly, and further, there is a drawback that continuous line production cannot be performed due to the batch type.

[0006] Therefore, as a method for solving the above problems in vapor deposition, the development of plating coating by spraying (mirror coating system) has been carried out. This mirror coating system by plating started from the first-generation silver mirror coating (reacting silver nitrate with ammonium) and was followed by the second-generation silver colloid-silver complex. However, with these first-generation and second-generation methods, it was difficult to expand them for industrial use due to problems with weather resistance, corrosion resistance, and paint unit price (cost). Therefore, as a third-generation method to solve the problems of these first-generation and second-generation methods, an "indium mirror coating system" using an indium paint with excellent weather resistance and corrosion resistance has emerged as the third generation.

[0007] Here, a brief explanation of indium is as follows. As is well known, indium is a rare metal with an atomic number of 49 and an element symbol of In. The pure substance is soft, silver-blue white, and a stable metal at room temperature. It is a metal with a low melting point that is easy to handle, has electrical conductivity and permeability, and has the rare characteristic of transmitting millimeter waves when in a thin film state. The indium paint using this indium is a paint made from an indium suspension, and can achieve a mirror finish (mirror coating) by spray coating, and has the characteristics of wide substrate suitability and no material selection required in a low-temperature range (80°C). Furthermore, since indium is excellent in weather resistance and corrosion resistance, it can also be applied to automotive exterior parts that have been difficult to introduce until now.

[0008] In recent years, for the casings of mobile phones, electronic devices, and information terminals, automotive parts (front grilles, bumpers), etc., radio wave permeability is required in addition to a mirror finish. That is, mobile phones, electronic devices, and information terminals have antennas, etc. inside the casing, and it is necessary to have radio wave permeability. Furthermore, since various radar device antennas such as distance measurement are installed near the front grilles and bumpers of automobiles, it is necessary to have radio wave permeability. Therefore, there has been a need for an indium paint using indium with radio wave permeability.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Incidentally, in order to stabilize the specular property of the mirror layer and maximize the mirror effect, it is necessary to uniformly conceal the base and form a film as thin as possible. Since the indium paint only needs to be able to conceal the base, the film thickness of the mirror layer may be at the 400 nm (nanometer) level.

[0011] However, in conventional hand spraying and screen coating, when trying to apply a thin coat, unevenness occurs and it is impossible to apply it evenly and thinly. Therefore, a coating technique capable of forming a thin film uniformly is essential.

[0012] , Also, since indium is as expensive as silver, in order to popularize the coating method using indium paint industrially, it is important to reduce the consumption amount of indium paint as much as possible. A paint technique that can apply with the minimum consumption amount of indium paint is essential and is the biggest issue.

[0013] Therefore, an object of the present invention is to provide a coating system capable of uniformly forming a thin film and suppressing the paint consumption amount to the minimum in coating using indium paint, and a coating method using the same.

Means for Solving the Problems

[0014] The coating system of the present invention is A coating system for coating a workpiece by forming an undercoat layer as a first layer by applying an undercoat paint, forming a middlecoat layer as a second layer by applying an indium paint, and forming a topcoat layer as a third layer by applying a topcoat paint, Work fixing means for mounting a workpiece to be coated, A coating robot provided with a spray gun for spraying paint toward the workpiece mounted on the work fixing means, Paint supply means for supplying paint to the spray gun, Paint filling means for filling the paint supply means with paint, and The work fixing means is It is equipped with a rotatable rotating shaft and a fixing jig for fixing connected to the rotating shaft, and the workpiece can revolve around the rotating shaft by rotating the rotating shaft with the workpiece fixed to the fixing jig. The spray gun comprises an undercoat spray gun for spraying an undercoat paint, a middle coat spray gun for spraying an indium paint, and a top coat spray gun for spraying a top coat paint. The paint supply means comprises an undercoat paint supply means for supplying an undercoat paint to the undercoat spray gun, an indium paint supply means for supplying an indium paint to the middle coat spray gun, and a top coat paint supply means for supplying a top coat paint to the top coat spray gun. The paint filling means comprises an undercoat paint filling means for filling the undercoat paint supply means with an undercoat paint, an indium paint filling means for filling the indium paint supply means with an indium paint, and a top coat paint filling means for filling the top coat paint supply means with a top coat paint. The indium paint supply means is mounted on the painting robot. After filling the undercoat paint supply means with an undercoat paint, the indium paint supply means with an indium paint, and the top coat paint supply means with a top coat paint, while revolving the workpiece by rotating the rotating shaft with the workpiece attached to the workpiece fixing means, an undercoat layer is formed by spraying the undercoat paint from the undercoat spray gun toward the revolving workpiece, then a middle coat layer as a mirror layer is formed by spraying the indium paint from the middle coat spray gun, and thereafter a top coat layer is formed by spraying the top coat paint from the top coat spray gun, thereby performing painting of the workpiece.

[0015] In the painting method of the present invention, an undercoat layer as the first layer is formed by applying an undercoat paint, a middle coat layer as the second layer is formed by applying an indium paint, and a top coat layer as the third layer is formed by applying a top coat paint, thereby performing a painting method for painting a workpiece. It includes a workpiece fixing means for mounting a workpiece to be painted, a painting robot equipped with a spray gun for spraying paint toward the workpiece mounted on the workpiece fixing means, a paint supply means for supplying paint to the spray gun, and a paint filling means for filling the paint supply means with paint. The workpiece fixing means includes a rotatable rotating shaft and a fixing jig connected to the rotating shaft. By rotating the rotating shaft with the workpiece fixed to the fixing jig, the workpiece can revolve around the rotating shaft. The spray gun includes an undercoat spray gun for spraying an undercoat paint, a middle coat spray gun for spraying an indium paint, and a top coat spray gun for spraying a top coat paint. The paint supply means includes an undercoat paint supply means for supplying an undercoat paint to the undercoat spray gun, an indium paint supply means for supplying an indium paint to the middle coat spray gun, and a top coat paint supply means for supplying a top coat paint to the top coat spray gun. The paint filling means includes an undercoat paint filling means for filling the undercoat paint supply means with an undercoat paint, an indium paint filling means for filling the indium paint supply means with an indium paint, and a top coat paint filling means for filling the top coat paint supply means with a top coat paint. The indium paint supply means is mounted on the painting robot, and is characterized by using a painting system. After filling the undercoat paint supply means with undercoat paint, the indium paint supply means with indium paint, and the topcoat paint supply means with topcoat paint, while rotating the rotating shaft with the work attached to the work fixing means to revolve the work, the undercoat paint is sprayed from an undercoat spray gun toward the revolving work to form an undercoat layer. Next, a middlecoat layer as a mirror layer is formed by spraying indium paint from a middlecoat spray gun, and then a topcoat layer is formed by spraying topcoat paint from a topcoat spray gun, thereby performing the painting of the work.

Effect of the Invention

[0016] In the painting system of the present invention and the painting method using the same, in the painting that is completed by forming three layers: an undercoat as the first layer for enhancing the adhesion between the base and the coating film, a middlecoat as the second layer for forming a mirror layer, and a topcoat as the third layer for protecting the painted surface and enhancing color variations, the paint is sprayed by a spray gun, the middlecoat is made of indium paint, and further, the work to be painted is revolved, and a rotary painting is performed in which the paint is applied toward the revolving work. The painting system is characterized in that a paint supply means for supplying indium paint to the spray gun is mounted on a painting robot.

[0017] Thus, in the painting system of the present invention, in the painting for forming three layers of an undercoat, a middlecoat, and a topcoat by a spray gun, since the middlecoat is made of indium paint, a mirror finish (mirror coating) can be achieved by spray painting, and it is possible to perform painting with a wide range of substrate suitability and without selecting materials in a low-temperature region (80°C). Also, since indium has excellent weather resistance and corrosion resistance, it is possible to paint automotive exterior parts, which have been difficult to introduce so far. Furthermore, since indium has radio wave permeability, in the present invention using indium paint, it is possible to obtain a painted product having radio wave permeability.

[0018] And at this time, in order to paint the workpiece by spraying paint with a spray gun toward the revolving workpiece while revolving the workpiece attached to the workpiece fixing means, unlike painting with a brush or hand spray painting, it is possible to form a uniform thin film at the nano level and minimize the paint.

[0019] Furthermore, in the painting apparatus of the present invention, since a syringe pump for supplying indium paint to the spray gun is mounted on the painting robot, the distance from the syringe pump to the spray gun can be shortened, the paint remaining in the paint hose can be minimized, and paint reduction can be achieved.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0021] The painting system of the present invention forms an undercoat layer as the first layer by applying an undercoat paint, forms a middlecoat layer as the second layer by applying an indium paint, and forms a topcoat layer as the third layer by applying a topcoat paint, thereby serving as a painting system for painting a workpiece.

[0022] And it has a workpiece fixing means for mounting the workpiece to be painted and a painting robot for painting the workpiece mounted on this workpiece fixing means. The painting robot is equipped with a spray gun for spraying paint toward the workpiece. Further, the painting system of the present invention has a paint supply means for supplying paint to the spray gun and a paint filling means for filling the paint supply means with paint.

[0023] The workpiece fixing means includes a rotatable rotating shaft and a fixing jig connected to this rotating shaft. The fixing jig is used to fix the workpiece to be painted to the rotating shaft, and by rotating the rotating shaft with the workpiece fixed to the fixing jig, the workpiece can revolve around the rotating shaft.

[0024] The spray gun includes an undercoat spray gun for spraying the undercoat paint, a middlecoat spray gun for spraying the indium paint, and a topcoat spray gun for spraying the topcoat paint. And by spraying the undercoat paint with the undercoat spray gun, an undercoat layer as the first layer is formed, by spraying the indium paint with the middlecoat spray gun, a mirror layer as the second layer is formed, and by spraying the topcoat paint with the topcoat spray gun, a topcoat layer as the third layer is formed.

[0025] The paint supply means for supplying paint to these spray guns includes an undercoat paint supply means for supplying undercoat paint to the undercoat spray gun, an indium paint supply means for supplying indium paint to the middlecoat spray gun, and a topcoat paint supply means for supplying topcoat paint to the topcoat spray gun. The indium paint supply means is mounted on the painting robot.

[0026] The paint filling means includes an undercoat paint filling means for filling the undercoat paint supply means with undercoat paint, an indium paint filling means for filling the indium paint supply means with indium paint, and a topcoat paint filling means for filling the topcoat paint supply means with topcoat paint.

[0027] In these configurations, the painting system of the present invention fills the undercoat paint supply means with undercoat paint, fills the indium paint supply means with indium paint, and fills the topcoat paint supply means with topcoat paint. Then, while rotating the rotating shaft with the work fixed to the fixing jig to revolve the work, the paint is sprayed from the spray gun toward the revolving work to paint the work.

[0028] More specifically, in the painting system of the present invention, as described above, an undercoat layer is formed by spraying undercoat paint from the undercoat spray gun. Next, a middlecoat layer as a mirror layer is formed by spraying indium paint from the middlecoat spray gun. Thereafter, a topcoat layer is formed by spraying topcoat paint from the topcoat spray gun, thereby painting the work.

[0029] Here, it is advisable to use a syringe pump comprising a cylindrical syringe body having an opening at its tip, a piston inserted into the syringe body so as to be able to advance and retreat, and a piston rod connected to the surface of the piston on the side opposite to the opening. The space formed between the piston and the opening is used as a paint filling space filled with paint. With the paint filling space filled with paint, the piston is advanced toward the opening side, so that the indium paint filled in the paint filling space is discharged from the opening.

[0030] In addition, an indium paint filling means for filling the paint filling space of the indium paint supply means includes a main body portion filled with indium paint inside and a discharge portion formed in the main body portion. By connecting the discharge portion of the indium paint filling means to the opening of the syringe pump as the indium paint supply means, the paint filling space and the inside of the main body portion are communicated with each other by the discharge portion. In this state, the piston of the indium paint supply means is retracted to make the inside of the syringe body negative pressure, so that the indium paint filled in the main body portion is filled into the paint filling space of the syringe pump as the indium paint supply means through the discharge portion.

[0031] Furthermore, as the indium paint filling means, in addition to the above, it may be composed of a main body portion formed of a stretchable material and filled with indium paint inside, a discharge portion formed in the main body portion, and a housing case that houses the main body portion in a sealed state with the discharge portion exposed to the outside. By connecting the discharge portion of the indium paint filling means to the opening of the syringe pump as the indium paint supply means, the paint filling space and the inside of the main body portion are communicated with each other by the discharge portion. In this state, the piston of the indium paint supply means is retracted to make the inside of the syringe body negative pressure, so that the indium paint filled in the main body portion is filled into the paint filling space of the syringe pump as the indium paint supply means through the discharge portion.

[0032] In the painting method of the present invention, using the painting system configured as described above, after filling the undercoat paint supply means with the undercoat paint, filling the indium paint supply means with the indium paint, and filling the topcoat paint supply means with the topcoat paint, while rotating the rotating shaft with the work attached to the work fixing means to revolve the work, the work is painted by spraying the paint toward the revolving work. Specifically, an undercoat layer is formed by spraying the undercoat paint from an undercoat spray gun, then a middlecoat layer as a mirror layer is formed by spraying the indium paint from a middlecoat spray gun, and thereafter, a topcoat layer is formed by spraying the topcoat paint from a topcoat spray gun, thereby painting the work.

Example

[0033] An example of the painting system of the present invention will be described with reference to the drawings. FIG. 1 is an image diagram for explaining the painting system of this example. In the figure, 1 is the painting system of this example, and W is the work to be painted.

[0034] The painting system 1 of this example includes a work fixing means for mounting the work W to be painted, a painting robot equipped with a spray gun for spraying paint toward the work mounted on the work fixing means, a paint supply means for supplying paint to the spray gun, and a paint filling means for filling the paint supply means with paint. By applying the undercoat paint to the work to form an undercoat layer as the first layer, then applying the indium paint to form a middlecoat layer as the second layer, and then applying the topcoat paint to form a topcoat layer as the third layer, the work is painted. The undercoat layer is a layer for enhancing the adhesion between the base and the paint film, the middlecoat layer is a layer for forming a mirror layer to achieve a mirror finish, and the topcoat layer is a layer for protecting the painted surface and enhancing color variations.

[0035] The workpiece fixing means will be described with reference to Fig. 1. In Fig. 1, reference numeral 2 denotes the workpiece fixing means. The workpiece fixing means 2 is provided with a rotating shaft 3, and the rotating shaft 3 is erected rotatably within the painting booth.

[0036] At the upper portion of the rotating shaft 3, a fixing jig 4 is radially connected toward the outer peripheral side of the rotating shaft 3. The workpiece W is to be attached to the tip of the fixing jig means 4. Therefore, the workpiece W is to be circularly arranged around the rotating shaft 3.

[0037] In this configuration, by rotating the rotating shaft 3 with the workpiece W fixed to the fixing jig 4, the workpiece W can revolve around the rotating shaft 3. In the drawing, it is assumed that four workpieces W are fixed to one workpiece fixing means 2.

[0038] Next, in the drawing, reference numeral 5 denotes a painting robot. The painting robot 5 in the present embodiment is a stationary type painting robot. The painting robot 5 will be described with reference to Fig. 2. Fig. 5 is a perspective view of the painting robot 5.

[0039] In Fig. 2, the painting robot 5 has a main body pillar 51. A first arm 52 is rotatably connected vertically to the upper side of the main body pillar 51, and a second arm 53 is rotatably connected vertically to the tip side of the first arm 52. A long ball screw spline 54 is connected to the tip portion of the second arm 53. Further, the ball screw spline 54 is movable in the width direction of the second arm 53, that is, in the left - right direction, and is rotatable along the circumferential direction. Spray gun devices 6 are mounted on both end portions of the ball screw spline 54. Therefore, in the present embodiment, there are provided two spray gun devices 6 and two workpiece fixing means 2 respectively.

[0040] Here, the spray gun device 6 will be described with reference to Fig. 1. In the drawing, the spray gun device 6 has a device main body portion 61, and the device main body portion 61 is mounted on the ball screw spline 54 of the painting robot 5.

[0041] At the tip of the apparatus main body 61, a support portion 62 is rotatably connected in the longitudinal direction of the ball screw spline 54. The support portion 62 has a plurality of support arms 63. Therefore, the support arms 63 will rotate like the propeller of the apparatus main body 61. Here, FIG. 3 is a view showing the support portion 62 from the side of the work fixing means 2. As also shown in the figure, the support portion 62 has three support arms 63, and these three support arms 63 are adjacent to each other at equal angles, and the angle between the support arms 63 is the same (about 120 degrees). And spray guns 7 are respectively attached to the tip portions of the three support arms 63.

[0042] The spray gun 7 includes an undercoat spray gun 7a for spraying an undercoat paint for forming an undercoat layer as the first layer, a middle coat spray gun 7b for spraying an indium paint for forming a mirror layer as the second layer, and a top coat spray gun 7c for spraying a top coat paint for forming a top coat layer as the third layer. And the undercoat spray gun 7a, the middle coat spray gun 7b, and the top coat spray gun 7c are respectively attached to the tips of the three support arms 63. Therefore, by rotating the support portion 62, the spray guns to be used can be replaced, and it is possible to form all layers of the undercoat layer, the middle coat layer, and the top coat layer by the same spray gun device 6.

[0043] The structure of the spray gun 7 used in this embodiment will be briefly described with reference to FIG. 4. FIG. 4 is a cross-sectional view for explaining the structure of the spray gun 7. The spray gun used in this embodiment is the same as a general atomizing spray gun used for painting, and a paint supply passage 71 is formed inside. The paint supply passage 71 has a paint inlet 71a for receiving paint and a paint injection port 71b for injecting the received paint toward the workpiece. The paint injection port 71b is opened and closed by advancing and retracting the needle 72 by the air for needle advancement and retraction supplied by the needle advancement and retraction air supply passage 75.

[0044] In addition, the spray gun 7 used in this embodiment is formed with an atomizing air supply passage 73 for atomizing the paint discharged from the paint injection port 71b and injecting it toward the workpiece. The tip of this atomizing air supply passage 73 is opened at an arbitrary position around the paint injection port 71b, and the base end side is connected to an atomizing air supply means (not shown). When air is supplied, atomizing air is supplied around the paint injection port 71b through the atomizing air supply passage 73, making it possible to atomize the paint discharged from the paint injection port 71b.

[0045] Furthermore, the spray gun 7 used in this embodiment is formed with a pattern air supply passage 74 for changing the ejection pattern of the paint atomized by the atomizing air to an arbitrary pattern. The tip of the pattern air supply passage 74 is opened outside the tip opening of the atomizing air supply passage 73, and the base end side is connected to a pattern air supply means (not shown). When air is supplied, pattern air is supplied around the tip opening of the atomizing air supply passage 73 through the pattern air supply passage 74, making it possible to change the ejection pattern of the paint atomized by the atomizing air.

[0046] Note that since the spray gun 7a for undercoat, the spray gun 7b for middle coat, and the spray gun 7c for top coat have the same configuration, duplicate explanations are omitted. Also, although illustration is omitted, in the spray gun device 6, inside the device main body 61 and the support arm 63, a paint supply path for supplying paint to the spray gun 7 and an air supply path for supplying various types of air (atomizing air, pattern air, air for needle advancement and retraction) to the spray gun are formed. Therefore, paint and various types of air can be supplied to the spray gun 7 through the inside of the spray gun device 6, eliminating the need to directly connect a paint hose and an air hose to the spray gun from the outside.

[0047] Next, the paint supply means will be described. In this embodiment, the paint supply means includes an undercoat paint supply means for supplying undercoat paint to the undercoat spray gun, an indium paint supply means for supplying indium paint to the middle coat spray gun, and a top coat paint supply means for supplying top coat paint to the top coat spray gun. And in this embodiment, all of the paint supply means are syringe pumps. In FIG. 1, 10 is an undercoat paint syringe as the undercoat paint supply means, 10b is a top coat paint syringe as the top coat paint supply means, and 8 is an indium paint syringe as the indium paint supply means.

[0048] Also, in this embodiment, the paint filling means includes an undercoat paint filling means for filling the undercoat paint syringe 10 with undercoat paint, an indium paint filling means for filling the indium paint syringe 8 with indium paint, and a top coat paint filling means for filling the top coat paint syringe 10b with top coat paint. Note that in FIG. 1, the undercoat paint filling means, the indium paint filling means, and the top coat paint filling means are omitted.

[0049] The indium paint supply means will be described with reference to Fig. 5. Fig. 5 is a partial cross-sectional view showing the structure of the syringe 8 for indium paint. In Fig. 5, 8 is the syringe for indium paint. The syringe 8 for indium paint has a cylindrical syringe body 81. At the tip of the syringe body 81, an opening 82 is formed which opens to the outside and communicates with the inside of the syringe body 81. Further, a piston 83 is inserted into the syringe body 81 so as to be able to advance and retreat, and a piston rod 84 is connected to the surface of the piston 83 on the side opposite to the opening 82. The space formed between the piston 83 and the opening 82 is a paint filling space 85 filled with paint.

[0050] With this configuration, the paint filling space 85 is filled with indium paint, and with the paint supply path formed in the apparatus main body portion 61 of the spray gun apparatus 6 and the opening 82 connected by a paint hose, by advancing the piston 83 toward the opening 82 side, the paint filled in the paint filling space 85 is discharged from the opening 82 into the paint hose, and the indium paint is supplied to the spray gun 7 through the paint hose, the paint supply path formed in the apparatus main body portion 61 and the support arm 63.

[0051] Note that in Fig. 1, 8 is the syringe for indium paint. That is, in this embodiment, the syringe 8 for indium paint is attached to the main body pillar 51 of the painting robot 5. Therefore, the paint hose connected to the spray gun apparatus 6 can be shortened, the remaining paint in the hose can be reduced, and the cost can be suppressed by reducing the usage fee of the expensive indium paint.

[0052] Next, the indium paint filling means for supplying indium paint to the syringe 8 for indium paint will be described. In Fig. 5, 9 is the indium paint filling means. The indium paint filling means 9 has a main body portion 91, and the main body portion 91 is filled with indium paint inside.

[0053] Further, a connecting portion 92 that can be connected to the opening 82 of the syringe 8 for indium paint is formed on the main body portion 91. This connecting portion 92 is open to the outside and communicates with the main body portion 91. In the figure, 93 is an opening / closing valve. In this embodiment, the main body portion 91 is a rigid container made of metal, resin, or the like.

[0054] When filling the syringe 8 for indium paint with indium paint by the indium paint filling means 9 configured as described above, the connecting portion 92 is connected to the opening 82 of the syringe 8 for indium paint, so that the paint filling space 85 and the inside of the main body portion 91 communicate with each other through the connecting portion 92. The opening / closing valve 93 is opened, and in this state, the piston 83 of the syringe 8 for indium paint is retracted to create a negative pressure inside the syringe body 81. Then, the indium paint filled in the main body portion 91 moves into the paint filling space 85 of the syringe 8 for indium paint through the connecting portion 92 and the opening 82, and thus, it becomes possible to fill the paint filling space 85 of the syringe 8 for indium paint with indium paint.

[0055] Therefore, in this embodiment, the filling of the indium paint into the syringe 8 for indium paint is performed by directly connecting the connecting portion 92 of the indium paint filling means 9 to the opening 82 of the syringe 8 for indium without using a paint filling hose. Thus, it is possible to eliminate the residual paint remaining in the filling hose when using a paint filling hose, and it is possible to eliminate the waste of indium paint.

[0056] Next, FIG. 6 is a partial cross-sectional view for explaining another configuration 9b of the indium filling means. The indium paint filling means 9b shown in FIG. 6 has a main body portion 94 formed of a stretchable material and filled with indium paint inside. A connecting portion 95 that communicates with the main body portion 94 and is open to the outside is formed on the main body portion 94.

[0057] Further, the main body portion 94 is housed in the housing case 96 with the connecting portion 95 exposed to the outside, and an opening / closing valve 97 is provided on the connecting portion 95. In this embodiment, the housing case 96 is a rigid container such as resin and is used to hold the main body portion 94 made of a stretchable material.

[0058] And when filling the indium paint syringe 8 with indium paint by the indium paint filling means 9b configured as described above, the connecting portion 95 is connected to the opening 82 of the indium paint syringe 8, so that the paint filling space 85 and the inside of the main body portion 94 communicate with each other through the connecting portion 95. The opening / closing valve 99 is opened. In this state, the piston 83 of the indium paint syringe 8 is retracted to make the inside of the syringe body 81 negative pressure. Then, the indium paint filled in the main body portion 94 moves to the paint filling space 85 of the indium paint syringe 8 through the connecting portion 95 and the opening 82. As a result, it becomes possible to fill the paint filling space 85 of the indium paint syringe 8 with indium paint.

[0059] Therefore, also with the indium paint filling means 9b shown in FIG. 6, since the connecting portion 95 is directly connected to the opening 82 of the indium syringe 8 to fill the indium paint, it is possible to eliminate the residual paint remaining in the filling hose when using the filling hose, and it is possible to eliminate the waste of indium paint. Further, in the indium paint filling means 9b shown in FIG. 6, since the main body portion 94 into which the indium paint is filled is formed of a stretchable material, there is an advantage that the main body portion 4 is easy to transport and store, and further, the paint is easy to handle.

[0060] In FIG. 5, an operating plate 88 screwed to a ball screw 87 connected to the shaft of the motor 86 is attached to the piston rod 84. By driving the motor 86 and rotating the ball screw 87, the operating plate 88 reciprocates at a constant speed along the ball screw 87. Thereby, the piston 83 is made movable forward and backward in the syringe body 81 through the piston rod 84.

[0061] Next, referring to FIG. 7, a primer syringe for supplying primer paint to an undercoat spray gun and a primer paint filling means for filling the primer syringe with primer paint will be described. FIG. 7 is a partial cross-sectional view showing the configuration of the primer syringe 10, where 10 is the primer syringe in FIG. 7.

[0062] The primer syringe 10 includes a cylindrical syringe body 101 having a discharge portion 102 at its tip, a piston 103 slidably inserted into the syringe body 101, and a piston rod 104 connected to the surface of the piston 103 on the side opposite to the discharge portion 102. The space formed between the piston 103 and the discharge portion 102 is a paint filling space 105 filled with paint. The discharge portion 102 communicates with the inside of the syringe body 101 and is open to the outside. It is formed in the syringe body 101 in a state of protruding from the syringe body 101. Further, the discharge portion 102 is provided with an opening / closing valve 108.

[0063] Then, the paint filling space 105 is filled with primer paint, the paint supply path formed in the apparatus main body portion 61 of the spray gun device 6 and the discharge portion 102 are connected by a paint hose, the opening / closing valve 108 is opened, and in this state, the piston 103 is advanced toward the discharge portion 102 side, so that the paint filled in the paint filling space 105 is discharged from the discharge portion 102 and supplied to the spray gun 7 through the paint hose, the paint supply path formed in the apparatus main body portion 61 and the support arm 63.

[0064] Next, an undercoat paint filling means for filling the syringe 10 for undercoat paint configured as described above with the undercoat paint will be described. In FIG. 7, reference numeral 11 denotes the undercoat paint filling means. The undercoat paint filling means includes a paint tank 12, a paint filling hose 13 that connects the paint filling space 105 and the paint tank 12, and a paint filling valve 14 and a paint filling pump 15 provided along the paint filling hose 13. Further, a paint filling passage 106 is formed inside the piston rod 104, and a filling port 107 continuous with the paint filling passage 106 is formed in the piston 103. That is, the undercoat paint filling means 11 in the present embodiment is composed of a paint tank 12, a filling hose 13, a filling pump 15, a filling valve 14, a paint filling passage 106, and a filling port 107. The distal end portion of the filling hose 12 is connected to the paint filling passage 106 formed in the piston rod 104, whereby the paint tank 12 and the paint filling space 105 communicate with each other through the filling hose 12.

[0065] Then, with the undercoat paint placed in the paint tank 12, the on-off valve 108 is closed, the filling valve 14 is opened, and the filling pump 15 is driven while retracting the piston 103, so that the undercoat paint in the paint tank 12 is filled into the paint filling space 105 of the undercoat paint supply syringe 10 through the paint filling passage 106 and the filling port 107. In the filled state, the on-off valve 108 is opened, the filling valve 14 is closed, and the piston 103 is advanced toward the discharge portion 102, so that the paint filled in the paint filling space 105 is discharged from the discharge portion 102 and supplied to the spray gun 7 through the paint hose, the paint supply passage formed in the apparatus main body portion 61, and the support arm 63. Note that the distal end portion of the filling hose 13 may be connected to the paint filling space 105, whereby the paint tank 12 and the paint filling space 105 communicate with each other through the filling hose 13.

[0066] In the primer syringe 10 shown in Fig. 7, an operating plate 88 screwed onto a ball screw 87 connected to the shaft of a motor 86 is attached to the piston rod 104. By driving the motor 86 and rotating the ball screw 87, the operating plate 88 is reciprocated at a constant speed along the ball screw 87. Thereby, the piston 103 is made movable forward and backward within the syringe body 101 via the piston rod 104.

[0067] Also, in this embodiment, the configurations of the topcoat paint syringe 10b and the topcoat paint filling means are the same as those of the primer paint syringe 10 and the primer paint filling means 11, so duplicate explanations are omitted.

[0068] Next, a painting method using the painting system of this embodiment configured as described above will be described. When painting a workpiece in this embodiment, first, the primer paint syringe 10 is filled with primer paint, the indium paint syringe 8 is filled with indium paint, and the topcoat paint syringe 10b is filled with topcoat paint by the method described above. Then, simultaneously, the workpiece W is fixed to the workpiece fixing means 2 by mounting the workpiece W on the fixing jig 4 of the workpiece fixing means 2.

[0069] Next, with the workpiece W fixed to the workpiece fixing means 2, the workpiece W is revolved by rotating the rotating shaft 3, and paint is sprayed toward the revolving workpiece.

[0070] That is, first, by rotating the support portion 62, the position of the undercoat spray gun 7a is adjusted so that the workpiece W can be painted with the undercoat spray gun 7a. Then, primer paint is supplied from the primer paint syringe 10 to the undercoat spray gun 7a, and various types of air (atomizing air, pattern air, needle advancing / retracting air) are supplied. Thereby, primer paint is sprayed from the undercoat spray gun 7a onto the workpiece W to form an undercoat layer on the workpiece W. And this undercoat layer enhances the adhesion between the base and the paint film.

[0071] Next, rotate the support portion 62 to replace the spray gun to be used so that the work W can be painted with the middle coat spray gun 7b. Then, supply indium paint from the indium paint syringe 8 to the middle coat spray gun 7b and supply various types of air (atomizing air, pattern air, needle advancing / retreating air). Thereby, spray the indium paint from the middle coat spray gun 7b onto the work W to form a middle coat layer as a mirror layer on the work W. And with this middle coat layer, a mirror layer is formed to achieve mirror finish painting.

[0072] And then, rotate the support portion 62 to replace the spray gun to be used so that the work W can be painted with the top coat spray gun 7c. Then, supply the top coat paint from the top coat paint syringe 10b to the top coat spray gun 7c and supply various types of air (atomizing air, pattern air, needle advancing / retreating air). Thereby, spray the top coat paint from the top coat spray gun 7c onto the work W to form a top coat layer on the work W. And with this top coat layer, the protection of the painted surface and the color variations are enhanced.

[0073] Note that any of the paints corresponding to the materials of the work, such as for general plastic materials, light metals, and enamels, may be used as the undercoat paint.

[0074] In addition, as a result of various experiments, it has been found that the mirror layer as the middle layer formed by indium paint can conceal the base uniformly and form a film as thin as possible to maximize the mirror effect. That is, while indium paint can conceal the base well, indium paint is expensive. Therefore, in this embodiment, the film thickness of the mirror layer is set at the 400-nanometer level. As described above, indium paint is a paint made from an indium suspension and can achieve a mirror finish (mirror coating) by spray coating. Since it is a commercially available product, detailed description is omitted. And in this embodiment, indium paint with the trade name ECOMIRROR49 (Eco Mirror 49) manufactured by Musashi Paint Holdings Co., Ltd. was used.

[0075] In addition, in this embodiment, the topcoat paint for forming the top layer uses a clear paint with an arbitrary color (color clear paint). By changing the color of the topcoat paint, it enriches the variations and enables various mirror coatings such as matte finish and colored finishes. However, since the color clear paint is also already commercially available, detailed description is omitted.

[0076] Thus, in the present invention, in the coating completed by forming three layers: an undercoat layer as the first layer for enhancing the adhesion between the base and the coating film, a middlecoat layer as the second layer for forming the mirror layer, and a topcoat layer as the third layer for protecting the painted surface and enhancing color variations, the paint is sprayed by a spray gun, the middlecoat is made of indium paint, and further, the workpiece to be coated is revolved, and a rotary coating is performed in which the paint is applied toward the revolving workpiece. It is a coating system, and furthermore, it is characterized in that a paint supply means for supplying indium paint to the spray gun is mounted on a coating robot.

[0077] Therefore, it is possible to achieve mirror finish (mirror coating) by spray coating, and it is possible to perform coating over a wide range of substrates at a low temperature range (80 °C) without selecting materials. In addition, since indium has excellent weather resistance and corrosion resistance, it is possible to coat exterior automotive parts, which have been difficult to coat heretofore. Furthermore, since indium has radio wave permeability, in the present invention using an indium paint, it is possible to obtain a coated product having radio wave permeability.

[0078] In addition, in order to paint the workpiece by spraying the paint with a spray gun toward the revolving workpiece while revolving the workpiece attached to the workpiece fixing means, unlike painting with a brush or hand-held spray, it is possible to form a uniform thin film at the nano level, and it is possible to minimize the paint.

[0079] Furthermore, since a syringe pump for supplying indium paint to the spray gun is mounted on the painting robot, the distance from the syringe pump to the spray gun can be shortened, the paint remaining in the paint hose can be minimized, and paint reduction can be achieved.

[0080] Moreover, in the present embodiment, when filling the indium paint syringe with indium paint, the indium paint filling means 9, 9b are directly connected to the indium paint syringe to fill the indium paint, eliminating the need to use a paint filling hose. Therefore, it is possible to eliminate the residual paint remaining in the filling hose when using a paint filling hose, and it is possible to eliminate waste of the indium paint.

Industrial Applicability

[0081] The coating system and coating method of the present invention are applicable to the entire coating system and coating method using indium paint.

Explanation of Reference Numerals

[0082] 1 Coating system 2 Workpiece fixing means 3 Rotating shaft 4 Fixing jig 5 Painting robot 51 Body pillar 52 First arm 53 Second arm 54 Ball screw spline 6 Spray gun device 61 Device main body part 62 Support part 63 Support arm 7 Spray gun 7a Undercoat spray gun 7b Middle coat spray gun 7c Top coat spray gun 71 Paint supply path 72 Needle 73 Atomizing air supply path 74 Pattern air supply path 75 Needle air supply path 8 Syringe for indium paint 81 Syringe body 82 Opening 83 Piston 84 Piston rod 85 Paint filling space 86 Motor 87 Ball screw 88 Actuating plate 9, 9b Indium paint filling means 91, 94 Main body part 92, 95 Connecting part 93, 97 On-off valve 96 Housing case 10 Syringe for undercoat paint 10b Syringe for supplying topcoat paint 101 Syringe body 102 Discharge part 103 Piston 104 Piston rod 105 Paint filling space 106 Paint filling path 107 Filling port 108 On-off valve 11 Undercoating paint filling means 12 Paint tank 13 Filling hose 14 Filling valve 15 Filling pump W Workpiece

Claims

1. An undercoat layer as the first layer is formed by applying an undercoat paint, then a middle coat layer as the second layer is formed by applying an indium paint, and thereafter a top coat layer as the third layer is formed by applying a top coat paint, thereby providing a painting system for painting a workpiece, a workpiece fixing means (2) for mounting a workpiece (W) to be painted, a painting robot (5) provided with a spray gun (7) for spraying paint toward the workpiece (W) mounted on the workpiece fixing means (2), paint supply means (8, 10, 10b) for supplying paint to the spray gun (7), and paint filling means (9, 9b, 11) for filling the paint supply means (8, 10, 10b) with paint, wherein the workpiece fixing means (2) comprises a rotatable rotary shaft (3) and a fixing jig (4) connected to the rotary shaft (3), and the workpiece (W) is revolvable about the rotary shaft (3) by rotating the rotary shaft (3) with the workpiece (W) fixed to the fixing jig (4), wherein the spray gun (7) comprises an undercoat spray gun (7a) for spraying an undercoat paint, a middle coat spray gun (7b) for spraying an indium paint, and a top coat spray gun (7c) for spraying a top coat paint, wherein the paint supply means comprises an undercoat paint supply means (10) for supplying an undercoat paint to the undercoat spray gun (7a), an indium paint supply means (8) for supplying an indium paint to the middle coat spray gun (7b), and a top coat paint supply means (10b) for supplying a top coat paint to the top coat spray gun, wherein the paint filling means comprises an undercoat paint filling means (11) for filling the undercoat paint supply means (10) with an undercoat paint, an indium paint filling means (9, 9b) for filling the indium paint supply means (8) with an indium paint, and a top coat paint filling means for filling the top coat paint supply means (10b) with a top coat paint, and the indium paint supply means (8) is mounted on the painting robot (5), After filling the undercoat paint supply means (10) with the undercoat paint, filling the indium paint supply means (8) with the indium paint, and filling the topcoat paint supply means (10b) with the topcoat paint, while rotating the rotary shaft (3) with the work (W) fixed to the fixing jig (4) to revolve the work (W), an undercoat layer is formed by spraying the undercoat paint from the undercoat spray gun (7a) toward the revolving work (W). Next, a middle coat layer as a mirror layer is formed by spraying the indium paint from the middle coat spray gun (7b). Then, a topcoat layer is formed by spraying the topcoat paint from the topcoat spray gun (7c). A painting system characterized by performing the painting of the work in this way.

2. The indium paint supply means (8) is a syringe pump including a cylindrical syringe body (81) having an opening (82) at the tip, a piston (83) inserted into the syringe body (81) so as to be able to advance and retreat, and a piston rod (84) connected to the surface of the piston (83) on the side opposite to the opening (82). The space formed between the piston (83) and the opening (82) is a paint filling space (85) filled with the paint. With the paint filling space (85) filled with the paint, the paint filled in the paint filling space (85) is discharged from the opening (82) by advancing the piston (83) toward the opening (82). The indium paint filling means (9) includes a main body portion (91) filled with the indium paint inside and a connecting portion (92) formed on the main body portion (91). The painting system according to claim 1, characterized in that by connecting the connecting portion (92) of the indium paint filling means (9) to the opening (82) of the indium paint supply means (8), the paint filling space (85) and the inside of the main body portion (91) are communicated with each other by the connecting portion (92). In this state, by retreating the piston (83) of the indium paint supply means (8) to make the inside of the syringe body (81) negative pressure, the indium paint filled in the main body portion (91) of the indium paint filling means (9) is filled into the paint filling space (85) of the indium paint supply means (8) through the connecting portion (92).

3. The indium paint supply means (8) is a syringe pump including a cylindrical syringe body (81) having an opening (82) at the tip, a piston (83) inserted into the syringe body (81) so as to be able to advance and retreat, and a piston rod (84) connected to the surface of the piston (83) on the side opposite to the opening (82). A space formed between the piston (83) and the opening (92) is defined as a paint filling space (85) filled with paint. With the paint filling space (85) filled with paint, the piston (83) is advanced toward the opening (82) to discharge the paint filled in the paint filling space (85) from the opening (82). The indium paint filling means (9b) includes a main body portion (94) formed of a stretchable material and filled with indium paint inside, a connecting portion (95) formed on the main body portion (94), and a housing case (96) that houses the main body portion (94) in a sealed state with the connecting portion (95) exposed to the outside. The coating system according to claim 1, characterized in that by connecting the connecting portion (95) of the indium paint filling means (9b) to the opening (82) of the indium paint supply means (8), the connecting portion (95) communicates the paint filling space (85) with the inside of the main body portion (94). In this state, the piston (83) of the indium paint supply means (8) is retracted to create a negative pressure inside the syringe body (81), so that the indium paint filled in the main body portion (94) of the indium paint filling means (9b) is filled into the paint filling space (85) of the indium paint supply means (8) through the connecting portion (95).

4. A painting method for painting a workpiece, comprising forming an undercoat layer as a first layer by applying an undercoat paint, forming a middlecoat layer as a second layer by applying an indium paint, and forming a topcoat layer as a third layer by applying a topcoat paint. A painting system comprising a workpiece fixing means (2) for mounting a workpiece (W) to be painted, a painting robot (5) including a spray gun (7) for spraying paint toward the workpiece (W) mounted on the workpiece fixing means (2), paint supply means (8, 10, 10b) for supplying paint to the spray gun (7), and paint filling means (9, 9b, 11) for filling the paint supply means (8, 10, 10b) with paint. The workpiece fixing means (2) includes a rotatable rotary shaft (3) and a fixing jig (4) connected to the rotary shaft (3). With the workpiece (W) fixed to the fixing jig (4), the rotary shaft (3) is rotated so that the workpiece (W) can revolve around the rotary shaft (3). The spray gun (7) includes an undercoat spray gun (7a) for spraying an undercoat paint, a middle coat spray gun (7b) for spraying an indium paint, and a top coat spray gun (7c) for spraying a top coat paint. The paint supply means includes an undercoat paint supply means (10) for supplying an undercoat paint to the undercoat spray gun (7a), an indium paint supply means (8) for supplying an indium paint to the middle coat spray gun (7b), and a top coat paint supply means (10b) for supplying a top coat paint to the top coat spray gun. The paint filling means includes an undercoat paint filling means (11) for filling the undercoat paint supply means (10) with an undercoat paint, an indium paint filling means (9, 9b) for filling the indium paint supply means (8) with an indium paint, and a top coat paint filling means for filling the top coat paint supply means (10b) with a top coat paint. The indium paint supply means is mounted on the painting robot (5), and is characterized by using a painting system. After filling the undercoat paint supply means (10) with an undercoat paint, the indium paint supply means (8) with an indium paint, and the top coat paint supply means (10b) with a top coat paint, the rotary shaft (3) is rotated with the workpiece (W) attached to the workpiece fixing means (5) to revolve the workpiece (W). While the workpiece (W) is revolving, an undercoat layer is formed by spraying an undercoat paint from the undercoat spray gun (7a) toward the revolving workpiece (W). Next, a middle coat layer as a mirror layer is formed by spraying an indium paint from the middle coat spray gun (7b). Then, a top coat layer is formed by spraying a top coat paint from the top coat spray gun (7c). Thus, the painting method is characterized by performing the painting of the workpiece.

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