Fastener coating system and fastener coating method

Abstract

To enable a head of a fastener to be coated automatically and with high quality, with a simple configuration.SOLUTION: A fastener coating system according to an embodiment is configured to coat a head of a fastener attached to an object. The fastener coating system comprises: a cup that has a void into which coating materials are charged and covers a head of the fastener by making an edge thereof contact a surface of the object; a supplying system that stores the coating materials and supplies the coating materials to the void in the cup; an ejecting system that ejects extra coating materials in the void from the cup; and a moving mechanism that changes relative positions of the cup and the object. In the cup are formed a supply port for supplying the coating materials into the void, a vent hole for ejecting air in the void and an ejection port for ejecting the extra coating materials from the void.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to a fastener coating system and method. [Background technology]

[0002] When painted parts are assembled with fasteners such as rivets, it is often necessary to paint the heads of the fasteners after assembly for the purpose of rust prevention, etc. In particular, in the case of rivets that are used by being deformed such as rivets that form their heads by caulking, it is not possible to paint them in advance. Therefore, devices have been proposed for sealing and painting the heads of fasteners (see, for example, Patent Document 1 or Patent Document 2). Also, a device has been proposed for painting fixtures such as brackets using a brush (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-161645 A [Patent Document 2] Japanese Utility Model Application Publication No. 07-039960 [Patent Document 3] Special Publication No. 2016-514036 Summary of the Invention [Problem to be solved by the invention]

[0004] However, particularly in the case of aircraft parts, high-quality painting is required under conditions such as the thickness of the paint applied to the fastener head must be within an allowable range and excessive paint must not adhere to the painted parts. Furthermore, some aircraft parts are several meters in size, and if they are to be transported to a painting booth or the like, not only will transportation equipment be required, but it will also lead to an increase in the manufacturing period. Therefore, it is desirable to be able to paint the fastener heads quickly in the work area where the aircraft parts are assembled or in an area nearby. As a result, in the case of aircraft parts, although the parts are assembled with a large number of rivets, the painting is almost always done manually using a brush.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a method for automatically painting fastener heads with high quality using a simple configuration. [Means for solving the problem]

[0006] A fastener coating system according to an embodiment of the present invention is for coating the head of a fastener attached to an object. The fastener coating system includes a cup having a gap for filling with paint and for covering the head of the fastener by contacting the edge of the cup with the surface of the object, a supply system for storing paint and supplying the paint to the gap in the cup, a waste liquid system for discharging excess paint in the gap from the cup, and a moving mechanism for changing the relative position between the cup and the object, and the cup is provided with a supply port for supplying the paint into the gap, an air vent for discharging air in the gap, and a waste liquid port for discharging the excess paint from the gap.

[0007] A method for coating fasteners according to an embodiment of the present invention involves producing a coated article by coating the head of a fastener attached to an object, the method comprising the steps of: changing a relative position between the object and a cup having a gap for filling with paint, the cup being formed with a supply port for supplying paint into the gap, an air vent for discharging air from the gap, and a waste liquid port for discharging excess paint from the gap, by using a moving mechanism to bring the edge of the cup into contact with a surface of the object to cover the head of the fastener; supplying the paint from the supply port into the gap while discharging the air from the air vent; and discharging excess paint from the gap through the waste liquid port. [Brief description of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a fastener coating system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example in which a multi-joint robot is used as the moving mechanism shown in FIG. 1. [Diagram 3] 3 is a perspective view showing an example of a detailed structure of a holder for fixing the cup and syringe shown in FIG. 2 to an arm of a multi-joint robot. [Figure 4] FIG. 4 is a vertical cross-sectional view showing a first structural example of the cup shown in FIGS. [Diagram 5] FIG. 5 is a plan view of the cup shown in FIG. 4 . [Figure 6] FIG. 4 is a vertical cross-sectional view showing a second structure example of the cup shown in FIGS. [Figure 7] An enlarged partial view of the O-ring groove shown in Figure 6. [Figure 8] FIG. 7 is a plan view of the cup shown in FIG. 6. [Figure 9] FIG. 4 is a vertical cross-sectional view showing a third structural example of the cup shown in FIGS. [Figure 10] FIG. 10 is a plan view of the cup shown in FIG. [Figure 11] 2 is a flowchart showing a procedure for painting the head of a fastener using the fastener painting system illustrated in FIG. 1 . [Figure 12]FIG. 13 is a diagram showing an example of the configuration of a control device for a movement mechanism and a cup provided in a fastener coating system according to a second embodiment of the present invention. [Figure 13] FIG. 11 is a configuration diagram of an exhaust system provided in a fastener coating system according to a third embodiment of the present invention. [Figure 14] FIG. 11 is a vertical cross-sectional view showing an example of the structure of a cup provided in a fastener coating system according to a third embodiment. [Figure 15] FIG. 15 is a plan view of the cup shown in FIG. [Figure 16] 16 is a cross-sectional view of the cup taken along the line AA of FIG. 15. [Figure 17] FIG. 15 is a perspective view of the cup shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A fastener coating system and a fastener coating method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] (First embodiment) (Configuration and Function of Fastener Painting System) FIG. 1 is a configuration diagram of a fastener coating system 1 according to a first embodiment of the present invention.

[0011] The fastener painting system 1 is a system that automatically paints the heads H of fasteners F, such as rivets and bolts attached to an object O, such as an aircraft structure. Painting that partially repairs the object to be painted is called touch-up. Therefore, the fastener painting system 1 can also be said to be a system that automatically touches up the heads H of fasteners F. The heads H of fasteners F that are the subject of automatic painting by the fastener painting system 1 may be bolt heads or prepared heads on the uncrushed side of a rivet, as well as artificial heads that are crushed when the rivet is crimped.

[0012] The fastener painting system 1 can be composed of a cup 2 for covering the head H of the fastener F, a supply system 3 for supplying paint P into the cup 2, an exhaust system 4 for discharging air from the cup 2, a waste liquid system 5 for discharging excess paint EP from the cup 2, and a moving mechanism 6 for changing the relative position between the cup 2 and the object O.

[0013] Cup 2 has a gap 7 therein for filling with paint P, and an opening 8 is formed so that head H of fastener F can be inserted into gap 7. Therefore, head H of fastener F can be covered by cup 2 by contacting the edge of cup 2 with the surface of object O. Cup 2 also has a supply port 2A for supplying paint P from supply system 3 into gap 7, an air vent 2B for discharging air from within gap 7 by exhaust system 4, and a waste liquid port 2C for discharging excess paint EP from gap 7 by waste liquid system 5.

[0014] The supply system 3 can be composed of, for example, a syringe 9 for storing paint P, a plunger 10 placed in the syringe 9, and a dispenser 11 that ejects paint P from the syringe 9 by supplying air to push the plunger 10.

[0015] Syringe 9 is a cylindrical container that stores paint P and discharges the paint P from an outlet formed at the tip. A plunger 10 is disposed inside syringe 9, and paint P is filled into the space on the outlet side of syringe 9 sealed by plunger 10. Meanwhile, when air is supplied to the space on the inlet side of syringe 9 partitioned off by plunger 10, the air pressure can push plunger 10 toward the paint P side.

[0016] The dispenser 11 is a device for dispensing a constant amount of liquid, which controls the flow rate of the paint P dispensed from the syringe 9 by supplying an appropriate flow rate of air to the space on the inlet side of the syringe 9 partitioned by the plunger 10. For this purpose, the dispenser 11 is connected to the inlet of the syringe 9 by an air tube 12.

[0017] The outlet of syringe 9 is connected to supply port 2A of cup 2. Therefore, a desired flow rate of paint P can be supplied from syringe 9 into gap 7 of cup 2 under the control of dispenser 11. Since commercially available luer-lock type syringes have female threads at their tips, if a luer-lock type syringe is used as syringe 9 while a male thread is formed in supply port 2A of cup 2, syringe 9 can be easily and stably fixed to cup 2.

[0018] The exhaust system 4 is provided to exhaust air present in the gap 7 when the paint P is supplied from the syringe 9 into the gap 7 of the cup 2. The exhaust system 4 can be composed of an air tube 13 for allowing air to flow. One end of the air tube 13 is connected to the vent 2B of the cup 2. A valve 14 for preventing backflow of air can be connected to the other end of the air tube 13. A valve that opens and closes by a control signal such as an electromagnetic valve may be used as the valve 14, but the configuration can be simplified if a check valve that does not require a control signal is used.

[0019] The waste liquid system 5 is a system that discharges excess paint EP in the gap 7 of the cup 2 from the waste liquid port 2C of the cup 2. In order to discharge the excess paint EP from the cup 2, it is sufficient to suck the excess paint EP in the gap 7. Therefore, the waste liquid system 5 can be composed of a vacuum device 15 such as a vacuum pump or an ejector, and a waste liquid trap 16.

[0020] The waste liquid trap 16 is an airtight tank that collects the excess paint EP recovered from the cup 2. A layer of excess paint EP and a layer of air are formed inside the waste liquid trap 16 due to the difference in weight. The waste liquid port 2C of the cup 2 is connected to the waste liquid trap 16 by a waste liquid tube 17, while the waste liquid trap 16 and the vacuum device 15 are connected by an air tube 18.

[0021] More specifically, the inlet of the waste liquid tube 17 is connected to the waste liquid port 2C of the cup 2, and the outlet of the waste liquid tube 17 is positioned so that it opens at the layer of excess paint EP. Meanwhile, the inlet of the air tube 18 is positioned so that it opens at the air layer, and the outlet of the air tube 18 is connected to the vacuum device 15. Therefore, when the vacuum device 15 is operated, air is sucked from the air layer in the waste liquid trap 16, reducing the pressure, and the excess paint EP can be sucked through the waste liquid port 2C of the cup 2.

[0022] When the gap 7 of the cup 2 is filled with the paint P, some of the paint P may flow into the exhaust air tube 13. For this reason, it is preferable to suck up the excess paint EP that has flowed into the exhaust air tube 13 through the waste liquid tube 17. As a result of a prototype test, it was confirmed that when discharging the excess paint EP from the cup 2, the excess paint EP that has flowed into the exhaust air tube 13 can be sucked up well by closing the valve 14 to prevent air from flowing into the exhaust air tube 13 from the atmosphere side, rather than opening the end of the exhaust air tube 13 to the atmosphere. Therefore, connecting the valve 14 such as a check valve to the end of the exhaust air tube 13 on the atmosphere side is advantageous mainly in terms of removing the excess paint EP that has flowed into the exhaust air tube 13.

[0023] The moving mechanism 6 is a device that performs relative positioning of the cup 2 with respect to the head H of the fastener F to be coated. In other words, the moving mechanism 6 can move at least one of the cup 2 and the object O. The moving mechanism 6 can be configured with a mechanical element that can perform translation in three orthogonal axial directions and rotational movement around a desired axis, such as tilting, similar to the drive shaft that moves the main shaft of a machine tool, and can also be configured with an articulated robot that is less expensive than the drive shaft for a machine tool and is easy to install in an assembly factory, etc., because the precision required for positioning the cup 2 is lower than that required for machining, etc.

[0024] FIG. 2 is a diagram showing an example of using an articulated robot 20 as the moving mechanism 6 shown in FIG. 1, and FIG. 3 is an oblique view showing an example of a detailed structure of a holder 22 for fixing the cup 2 and syringe 9 shown in FIG. 2 to the arm 21 of the articulated robot 20.

[0025] The cup 2 can be moved by an arm 21 of an articulated robot 20 having a typical cantilever structure as shown in Fig. 2. In this case, it is practical to attach not only the cup 2 but also the syringe 9 integrated with the cup 2 to the tip of the arm 21 as an end effector 23. The arm 21 of the articulated robot 20 is also called a manipulator.

[0026] 3, the cup 2 and syringe 9 connected by a luer lock or the like can be held in a snap-in holder 22 that can be easily attached and detached by a snap fit. A flange 24 for fixing to the arm 21 of the articulated robot 20 is provided at the end of the holder 22. Therefore, the cup 2 and syringe 9 can be easily attached to, detached from, or replaced by the holder 22 fixed to the arm 21 via the flange 24.

[0027] 3, the check valve 14A is also fixed to the holder 22 because its size and weight are such that it can be supported by the arm 21. This makes it possible to keep the distance between the check valve 14A and the cup 2 constant and reduce the risk of interference with the exhaust air tube 13 when the arm 21 of the articulated robot 20 is moved.

[0028] Regardless of whether the moving mechanism 6 is configured by the articulated robot 20 or not, the moving mechanism 6 has a control device 6A for driving the moving mechanism 6 and a storage device 6B for storing a numerical control (NC) control program and the like for the moving mechanism 6. Position information of the head H of the fastener F is required to perform relative positioning of the cup 2 with respect to the head H of the fastener F.

[0029] Therefore, a control program for the moving mechanism 6, which includes three-dimensional (3D) position information of the head H of the fastener F to be touched up, can be stored in the memory device 6B. Then, the control device 6A controls the moving mechanism 6 in accordance with the control program for the moving mechanism 6, which includes the position information of the head H of the fastener F stored in the memory device 6B, and the cup 2 can be positioned relative to the head H of the fastener F.

[0030] In order to prevent paint P from leaking from the gap between the cup 2 and the surface of the object O when paint P is filled in the gap 7 in the cup 2, it is important to bring the edge of the cup 2 into close contact with the surface of the object O around the head H of the fastener F. For this reason, in order to paint the head H of the fastener F, it is necessary to position the cup 2 in a two-dimensional (2D) direction in a plane perpendicular to the longitudinal direction of the fastener F, and then position it in the longitudinal direction of the fastener F so that the positions of the gap 7 and the opening 8 in the cup 2 are spaced apart from the position of the head H of the fastener F in the longitudinal direction of the fastener F.

[0031] Positioning of cup 2 in the length direction of fastener F involves determining the position of cup 2 so that, when paint P is filled into gap 7 in cup 2, the edge of cup 2 comes into close contact with the surface of object O to such an extent that paint P does not leak from the gap between cup 2 and the surface of object O. For this reason, positioning of cup 2 in the length direction of fastener F requires higher accuracy than positioning of cup 2 in a direction perpendicular to the length direction of fastener F.

[0032] A force sensor 25 is standardly provided on the arm 21 of a typical articulated robot 20. Thus, when the articulated robot 20 is used as the moving mechanism 6, it is possible to determine whether or not the edge of the cup 2 has come into contact with the surface of the object O based on the reaction force from the surface of the object O to the cup 2 measured by the force sensor 25. More specifically, the force sensor 25 measures the resistance from the surface of the object O to the cup 2 in the length direction of the fastener F, and when the resistance reaches a threshold value, it is possible to determine that the edge of the cup 2 has come into contact with the surface of the object O and complete the positioning of the cup 2 in the length direction of the fastener F.

[0033] In this case, the robot control device 26 of the articulated robot 20, which is the control device 6A of the moving mechanism 6, can be provided with a function to drive the arm 21 to move the cup 2 in the longitudinal direction of the fastener F to bring the cup 2 closer to the surface of the object O, while acquiring the resistance force from the surface of the object O on the cup 2 from the force sensor 25, and to stop driving the arm 21 and the movement of the cup 2 in the longitudinal direction of the fastener F when the resistance force acquired from the force sensor 25 reaches a threshold value.

[0034] Of course, even if the articulated robot 20 is not used as the moving mechanism 6, a force sensor can be provided in a similar manner to make it possible to determine whether the edge of the cup 2 has come into contact with the surface of the object O.

[0035] Once the positioning of the cup 2 relative to the head H of the fastener F is complete, it becomes necessary to supply paint P into the gap 7 of the cup 2 that covers the head H of the fastener F, and it is appropriate to start supplying paint P after the positioning of the cup 2 is complete. Therefore, the supply of paint P into the cup 2 by the supply system 3 must be linked to the movement of the cup 2 by the movement mechanism 6.

[0036] Therefore, the control device 6A of the moving mechanism 6 such as the robot control device 26 can be provided with a function of outputting a control signal to the dispenser 11 to instruct the start and stop of the operation of the dispenser 11. A standard dispenser 11 is provided with a function of setting and controlling the discharge conditions such as the flow rate, flow velocity, or pressure of the liquid to be discharged. Therefore, if the discharge conditions such as the appropriate flow rate and discharge pressure of the paint P determined by a test or the like are set in the dispenser 11 in advance, the paint P can be discharged from the syringe 9 into the gap 7 in the cup 2 under the appropriate discharge conditions simply by outputting a trigger signal to switch the dispenser 11 ON and OFF from the control device 6A of the moving mechanism 6.

[0037] Making the total amount of paint P to be discharged into the gap 7 in the cup 2 larger than the volume of the gap 7 helps to avoid the inconvenience of air remaining in the gap 7 in the cup 2. In other words, it is preferable that the supply system 3 is configured to supply an amount of paint P to the gap 7 in the cup 2 that is larger than the volume of the gap 7.

[0038] Therefore, the control device 6A, such as the robot control device 26, can be provided with a function to estimate the amount of paint P ejected into the gap 7 in the cup 2 based on the ejection flow rate of the paint P and the operating time of the dispenser 11, and when it is determined that the required amount of paint P has been supplied to the gap 7 in the cup 2, a function to switch the operating state of the dispenser 11 to OFF by outputting an operation stop signal to the dispenser 11 can be provided.

[0039] Alternatively, the dispenser 11 may be configured to estimate the amount of paint P discharged into the gap 7 in the cup 2 based on the discharge flow rate of the paint P and the operation time of the dispenser 11, and autonomously switch the operation state to OFF when it is determined that the required amount of paint P has been supplied to the gap 7 in the cup 2. In that case, the dispenser 11 may be configured to notify the control device 6A such as the robot control device 26 that the operation state of the dispenser 11 has been switched to OFF.

[0040] When the gap 7 in the cup 2 is filled with paint P, the head H of the fastener F becomes immersed in the paint P inside the cup 2, and it is possible to obtain the effect that the head H of the fastener F is coated with paint P. After that, the vacuum device 15 of the waste liquid system 5 is operated, and the paint P in the gap 7 that has not adhered to the head H of the fastener F is discharged from the waste liquid outlet 2C as surplus paint EP.

[0041] Therefore, the coating conditions for the head H of the fastener F include the conditions for discharging the paint P into the gap 7 in the cup 2 by the supply system 3, as well as the waiting time from when the gap 7 in the cup 2 is filled with the paint P until the excess paint EP in the gap 7 starts to be discharged, the pressure of the excess paint EP, etc. As with the conditions for discharging the paint P into the gap 7 in the cup 2, appropriate conditions for these coating conditions can also be determined in advance by testing or the like.

[0042] The waiting time with the gap 7 in the cup 2 filled with the paint P corresponds to the time from when the operation of the dispenser 11 is switched off to when the vacuum device 15 is activated. On the other hand, the pressure of the excess paint EP can be set as an operating condition of the vacuum device 15.

[0043] Therefore, the control device 6A of the moving mechanism 6, such as the robot control device 26, can be provided with a function of outputting a control signal to the vacuum device 15 to instruct the vacuum device 15 to start and stop operation. In this way, it becomes possible to control the standby time with the gap 7 in the cup 2 filled with the paint P by outputting a trigger signal to the vacuum device 15 from the control device 6A, such as the robot control device 26, to start operation after an appropriate time has elapsed since the operation of the dispenser 11 was switched OFF.

[0044] In this way, by appropriately setting and controlling the operating conditions of the dispenser 11 and the vacuum device 15, it is possible to adjust the coating conditions, such as the discharge flow rate of the paint P, the discharge pressure of the paint P, the discharge amount of the paint P, the waiting time after completion of the discharge of the paint P, and the pressure of the excess paint EP. Therefore, by appropriately setting these coating conditions, not only can the paint P be evenly applied to the head H of the fastener F, but it is also possible to adjust the film thickness of the paint P applied to the head H of the fastener F to a desired film thickness. In other words, the film thickness of the paint P applied to the head H of the fastener F can be adjusted.

[0045] Next, an example of the detailed structure of the cup 2 will be described.

[0046] FIG. 4 is a vertical cross-sectional view showing a first structural example of the cup 2 shown in FIGS. 1 to 3, and FIG. 5 is a plan view of the cup 2 shown in FIG.

[0047] As in the first structural example illustrated in Figures 4 and 5, the cup 2 has a gap 7 for filling with paint P, and an opening 8 for inserting the head H of the fastener F into the gap 7. The periphery of the opening 8 forms the edge of the cup 2 for contacting the surface of the object O. In the example shown in Figures 4 and 5, the shape of the opening 8 is circular. Therefore, the edge of the cup 2 is annular.

[0048] As described above, the cup 2 is formed with the supply port 2A for supplying the paint P into the gap 7, the ventilation port 2B for discharging the air within the gap 7, and the waste liquid port 2C for discharging the excess paint EP from the gap 7. In the example shown in Figures 4 and 5, a male thread is formed on the outer periphery of the cylindrical portion that forms the supply port 2A so that the cup 2 can be connected to the tip of a luer lock type syringe.

[0049] The cup 2 can be made of any material, such as resin or metal, as long as the necessary strength is ensured. Therefore, it is practical to make the cup 2 a rigid body. On the other hand, when the gap 7 in the cup 2 is filled with paint P, it is desirable from the viewpoint of reducing cleaning work to prevent the paint P from leaking from the gap between the edge of the cup 2 and the surface of the object O. In that case, it is preferable from the viewpoint of more reliably adhering the edge of the cup 2 to the surface of the object O to make at least a part of the edge of the cup 2 that comes into contact with the surface of the object O an elastic body rather than a rigid body.

[0050] 4 and 5, an O-ring 30 can be attached to the edge of the cup 2 formed around the opening 8. This allows the edge of the cup 2 formed by the O-ring 30 to be tightly attached to the surface of the object O.

[0051] In addition, if the object O and cup 2 are positioned so that the opening 8 of the cup 2 is oriented generally horizontally and covers the head H of the fastener F, in other words, if the object O is positioned so that the head H of the fastener F protrudes generally horizontally from the surface of the object O, it is possible to position the air vent 2B for discharging air from the gap 7 at the highest position, while forming the waste liquid port 2C for discharging excess paint EP from the gap 7 at the lowest position.

[0052] More specifically, when the normal direction of the surface on which the edge of cup 2 lies is horizontal, the position of air vent 2B can be determined so that the height of air vent 2B opening within gap 7 of cup 2 is the highest within gap 7, while the position of waste liquid outlet 2C can be determined so that the height of waste liquid outlet 2C opening within gap 7 of cup 2 is the lowest within gap 7.

[0053] Then, while the paint P is being discharged into the gap 7 of the cup 2, the paint P gradually accumulates in the gap 7 from below due to gravity, so that the air remaining in the gap 7 is gradually moved upward, and it is possible to reliably discharge the air from the uppermost ventilation hole 2B. In other words, it is possible to prevent air from remaining in the gap 7 of the cup 2 after the filling of the gap 7 of the cup 2 with the paint P is completed. As a result, it is possible to apply the paint P evenly to the head H of the fastener F.

[0054] On the other hand, when discharging excess paint EP from within the gap 7 of the cup 2, the excess paint EP moving downward due to gravity can be reliably discharged from the waste liquid outlet 2C at the bottom. In other words, it is possible to prevent excess paint EP from remaining in the gap 7 of the cup 2 after the discharge of the excess paint EP from within the gap 7 of the cup 2 is completed. As a result, not only is it easy to clean the cup 2, but it is also possible to always fill the gap 7 of the cup 2 with fresh paint P when painting the heads H of multiple fasteners F in sequence.

[0055] FIG. 6 is a longitudinal cross-sectional view showing a second structural example of the cup 2 shown in FIGS. 1 to 3, FIG. 7 is a partially enlarged view of the groove 31 for the O-ring 30 shown in FIG. 6, and FIG. 8 is a plan view of the cup 2 shown in FIG. 6.

[0056] 6 to 8, when the O-ring 30 is pressed against the surface of the object O, the depth of the groove 31 for accommodating the O-ring 30 can be set to be equal to or greater than the diameter of the O-ring 30 in cross section so that the O-ring 30 in a crushed state does not protrude from the edge of the cup 2. In other words, a recess 31A can be formed in the bottom surface of the groove 31 for accommodating the O-ring 30.

[0057] Then, when the O-ring 30 is pressed against the surface of the object O, the O-ring 30 is completely pressed into the groove 31 in a crushed state. Therefore, after the O-ring 30 is pressed against the surface of the object O, the elastic force of the crushed O-ring 30 keeps the O-ring 30 in close contact with the surface of the object O, and the gap between the cup 2 and the surface of the object O caused by the presence of the O-ring 30 can be eliminated. As a result, it is possible to prevent excess paint EP from accumulating between the cup 2 and the surface of the object O, and to prevent the excess paint EP from dripping downward after the painting is completed and the cup 2 is retracted.

[0058] Additionally, in the second structural example, the gap 7 in the cup 2 is formed with inclined wall surfaces 32 so as to ideally allow air flow and excess paint EP to move. That is, the wall surfaces 32 of the gap 7 taper so that the height gradually decreases toward the opening 8 of the cup 2 at the upper part of the gap 7. On the other hand, the wall surfaces 32 of the gap 7 taper so that the height gradually increases toward the opening 8 of the cup 2 at the lower part of the gap 7.

[0059] More specifically, when the normal direction of the surface on which the edge of the cup 2 lies is horizontal, the wall surface 32 of the gap 7 is inclined so that the bottom of the gap 7 is lower than the bottom of the opening 8. On the other hand, when the normal direction of the surface on which the edge of the cup 2 lies is horizontal, the wall surface 32 of the gap 7 is inclined so that the top of the gap 7 is higher than the top of the opening 8.

[0060] In this case, if a tubular depression with a V-shaped cross section is formed within gap 7 and wall surface 32 of gap 7 is tapered so that the entire gap 7 gradually narrows toward opening 8, the shape of wall surface 32 will be the same as the side of a truncated cone, and the structure of cup 2 will be simpler, making it easier to design and manufacture cup 2.

[0061] By inclining the wall surface 32 of the gap 7 in this manner, the air remaining in the gap 7 can be more reliably guided to the uppermost ventilation port 2B while the paint P is being discharged into the gap 7 of the cup 2. As a result, it is possible to more reliably prevent air from remaining in the gap 7 of the cup 2 after filling of the gap 7 of the cup 2 with the paint P is completed.

[0062] On the other hand, when the excess paint EP is discharged from the gap 7 of the cup 2, the excess paint EP can be more reliably guided to the waste liquid outlet 2C at the bottom. As a result, after the excess paint EP has been discharged from the gap 7 of the cup 2, it is possible to more reliably prevent the excess paint EP from remaining in the gap 7 of the cup 2. In addition, after painting is completed and the cup 2 is retracted, it is possible to prevent the excess paint EP from dripping downward from the opening 8 of the cup 2. This also has the effect of reducing the amount of paint P consumed.

[0063] FIG. 9 is a vertical cross-sectional view showing a third structural example of the cup 2 shown in FIGS. 1 to 3, and FIG. 10 is a plan view of the cup 2 shown in FIG.

[0064] 9 and 10, a ring-shaped elastic sponge 33 can be attached as a packing to the edge of the cup 2 instead of the O-ring 30. That is, the edge of the cup 2 can be formed of the sponge 33. The sponge 33 can be made of a desired porous material such as foamed rubber.

[0065] In particular, sponge washers with double-sided tape are commercially available, and sponge 33 can be easily attached to the edge of cup 2 with the tape. Therefore, in the third structural example, groove 31 for embedding O-ring 30 as in the first and second structural examples is not necessary, and as a result, supply port 2A and waste liquid port 2C can be located closer to opening 8 than when O-ring 30 is used.

[0066] This not only makes it possible to easily guide the excess paint EP to the waste liquid port 2C for discharge and recovery while preventing the excess paint EP from dripping from the opening 8 of the cup 2 after the cup 2 is retracted, but also makes it possible to reduce the volume of the gap 7. Therefore, compared to the case where the O-ring 30 is used, the effect of reducing the consumption of the excess paint EP and paint P can be obtained.

[0067] Moreover, unlike a typical O-ring 30, the sponge 33 easily deforms to follow the shape of the surface of the object O by crushing the minute holes. Therefore, the sponge 33 can be tightly attached to the surface of the object O even if the edge of the cup 2 is not pressed against the surface of the object O strictly perpendicularly.

[0068] In addition, because the sponge 33 has liquid absorbency, even if excess paint EP flows between the edge of the cup 2 to which the sponge 33 is attached and the surface of the object O, the excess paint EP can be absorbed by the sponge 33. That is, when painting is completed and the cup 2 is pulled away from the surface of the object O, the sponge 33 returns to its original shape and absorbs the excess paint EP into the tiny holes inside. Therefore, even if the edge of the cup 2 is not pressed strictly perpendicularly against the surface of the object O and excess paint EP flows near the sponge 33, the inconvenience of excess paint EP dripping downward after the cup 2 is retracted can be avoided.

[0069] In other words, while the paint P is being dispensed into the gap 7 of the cup 2, the sponge 33 functions as a gasket to prevent leakage of the paint P, and after painting is completed, it functions as an absorbent to absorb excess paint EP and prevent it from dripping downward.

[0070] The normal direction of the surface of the object O is not necessarily strictly horizontal, and the surface of the object O may not be flat but may be a curved surface with a small curvature or multiple flat surfaces with slightly different normal directions. For this reason, when using any of the cups 2 of the first to third structural examples, during actual painting, the normal direction of the surface on which the rim of the cup 2 lies may be inclined from the horizontal direction within a range of 0 degrees to 45 degrees depending on the position and shape of the surface of the object O.

[0071] It has been confirmed through prototype testing that when the cup 2 is tilted, particularly when the cup 2 of the third structural example is used, not only can the paint P be most effectively prevented from leaking while the paint P is being ejected into the gap 7 of the cup 2, but also the inconvenience of excess paint EP dripping downward can be most effectively prevented even after the cup 2 is retracted after painting is completed.

[0072] (How to paint fasteners) Next, a fastener coating method for producing a coated article by using the fastener coating system 1 to paint the head H of a fastener F attached to an object O will be described.

[0073] FIG. 11 is a flowchart showing a flow of painting the head H of the fastener F using the fastener painting system 1 illustrated in FIG.

[0074] First, in step S1, the cup 2 is positioned in a direction perpendicular to the length direction of the fastener F so that the cup 2 is on the axis of the fastener F. Specifically, a control program including position information of the fastener F stored in the storage device 6B is read into the control device 6A, and the moving mechanism 6 is driven under the control of the control device 6A so that the center position of the opening 8 of the cup 2 and the central axis of the fastener F are substantially on the same straight line. If the moving mechanism 6 is an articulated robot 20 as exemplified in Fig. 2, the arm 21 is driven under the control of the robot control device 26.

[0075] This changes the relative position between the cup 2 and the object O, and the cup 2 is positioned such that the opening 8 of the cup 2 faces the head H of the fastener F and is spaced apart from the head H of the fastener F in the longitudinal direction of the fastener F.

[0076] Next, in step S2, the cup 2 is positioned in the length direction of the fastener F so as to seal the head H of the fastener F with the cup 2. Specifically, the control device 6A controls the moving mechanism 6 based on a control program including position information of the fastener F so that the edge of the cup 2 comes into contact with the surface of the object O. To this end, the moving mechanism 6 is driven to move the cup 2 in parallel in the length direction of the fastener F. As a result, the edge of the cup 2 gradually approaches the surface of the object O, and finally comes into contact with the surface of the object O.

[0077] When the edge of the cup 2 comes into contact with the surface of the object O, a resistance force is received from the surface of the object O. For this reason, in the case where the moving mechanism 6 is an articulated robot 20 equipped with a force sensor 25 as exemplified in Fig. 2, the force sensor 25 detects the resistance force from the surface of the object O, and the force sensor 25 notifies the robot control device 26 that the resistance force has been detected. As a result, the robot control device 26 can detect that the edge of the cup 2 has come into contact with the surface of the object O, and stop driving the arm 21.

[0078] When the positioning of the cup 2 in the longitudinal direction of the fastener F is completed, a packing such as an O-ring 30 or a sponge 33 provided on the edge of the cup 2 comes into close contact with the surface of the object O, and the head H of the fastener F is covered by the cup 2. In other words, the periphery of the head H of the fastener F is sealed by the cup 2.

[0079] Next, in step S3, the cup 2 is filled with paint P. Specifically, a trigger signal for operating the dispenser 11 is output from the control device 6A to the dispenser 11. As a result, the dispenser 11 is operated and air is supplied into the syringe 9. As a result, the plunger 10 in the syringe 9 is pressed down by air pressure, and the paint P in the syringe 9 is discharged from the tip of the syringe 9 toward the supply port 2A of the cup 2. The paint P discharged from the syringe 9 is supplied into the gap 7 from the supply port 2A of the cup 2.

[0080] Since gap 7 in cup 2 is a space closed by the surface of object O, the air pressure increases when paint P flows in. As a result, the air in gap 7 is discharged from vent 2B. In other words, the paint P, whose liquid level gradually rises in gap 7 in cup 2, pushes the air in gap 7 out through vent 2B.

[0081] The air that has entered the ventilation port 2B is released into the atmosphere through the air tube 13 and the valve 14. Therefore, the air pressure in the gap 7 increases only to a certain extent, making it possible to continue discharging the paint P into the gap 7. In other words, the paint P is supplied into the gap 7 while the air in the gap 7 is being discharged from the ventilation port 2B.

[0082] Then, an amount of paint P slightly larger than the volume of the space in the cup 2 closed by the surface of the object O is supplied into the gap 7. This allows the air in the gap 7 to be completely exhausted through the ventilation hole 2B, and the gap 7 to be completely filled with paint P. As a result, the paint P can be applied evenly to the head H of the fastener F.

[0083] Although some of the paint P may enter the vent 2B and flow into the air tube 13, the total amount of paint P discharged is determined so that the paint P remains in the air tube 13, and therefore the paint P will not overflow to the outside through the valve 14. In other words, the dispenser 11 is controlled so as to stop at the timing when an amount of paint P that is greater than the volume of the gap 7 in the cup 2 and does not overflow from the valve 14 is discharged into the gap 7 in the cup 2.

[0084] Next, in step S4, excess paint EP in the gap 7 of the cup 2 is discharged from the waste liquid port 2C. That is, after filling of the paint P into the cup 2 is completed and a required waiting time has elapsed, the excess paint EP in the gap 7 of the cup 2 is sucked by the operation of the vacuum device 15.

[0085] Specifically, a trigger signal for activating the vacuum device 15 is output from the control device 6A to the vacuum device 15. This activates the vacuum device 15, and air is sucked from the air layer in the waste liquid trap 16 via the air tube 18. This causes the pressure of the air layer in the waste liquid trap 16 to become negative, and the liquid level of the excess paint EP in the waste liquid trap 16 rises. As a result, the excess paint EP is sucked from the space 7 of the cup 2 and the air tube 13 into the waste liquid trap 16 via the waste liquid port 2C and the waste liquid tube 17 and collected therein.

[0086] When surplus paint EP is being sucked, a valve 14 such as a check valve connected to the atmospheric end of the air tube 13 is closed. This prevents air from flowing back through the air tube 13, and keeps the gap 7 of the cup 2 sealed. As a result, surplus paint EP can be sucked up well.

[0087] Next, in step S5, the cup 2 moves to the retreat position. That is, the moving mechanism 6 such as the articulated robot 20 is driven under the control of the control device 6A such as the robot control device 26, and the cup 2 is separated from the surface of the object O. This completes the localized painting of the head H of the fastener F, i.e., the touch-up.

[0088] Then, if there are still heads H of fasteners F remaining to be painted, the operations and manipulations from step S1 to step S5 are repeated again, thereby painting the heads H of all fasteners F. In other words, a coated article consisting of an object O with the heads H of fasteners F painted can be manufactured.

[0089] (effect) The above fastener painting system 1 and fastener painting method involve holding an airtight cup 2 capable of covering the head H of a fastener F with a moving mechanism 6 such as an articulated robot 20, filling paint P into the cup 2 with a supply system 3 consisting of a syringe 9, a dispenser 11, etc., and then discharging excess paint EP from the cup 2 with a waste liquid system 5 consisting of a vacuum device 15, etc.

[0090] Therefore, the fastener painting system 1 and the fastener painting method can automate the painting of the head H of the fastener F. As a result, the labor and work time required to paint the head H of the fastener F can be reduced compared to when a worker paints the head H manually.

[0091] In particular, by appropriately setting painting conditions such as the discharge conditions of the paint P supplied into the cup 2, the waiting time from filling the cup 2 with paint P to discharging the excess paint EP, and the discharge pressure of the excess paint EP, not only can the variation in painting quality be reduced and made uniform compared to when an operator paints manually, but the film thickness of the paint P after painting can also be adjusted.

[0092] In addition, since the operator of the fastener painting system 1 will have fewer opportunities to handle the paint P, safety can be improved compared to when a worker paints manually.

[0093] Second Embodiment FIG. 12 is a diagram showing an example of the configuration of a control device 6A of a moving mechanism 6 and a cup 2 provided in a fastener coating system 1A according to the second embodiment of the present invention.

[0094] A fastener coating system 1A in the second embodiment shown in Fig. 12 differs from the fastener coating system 1 in the first embodiment in that it has a configuration that enables correction of the relative position of the cup 2 with respect to the head H of the fastener F based on information acquired by a sensor 40. Since other configurations and operations of the fastener coating system 1A in the second embodiment are substantially the same as those of the fastener coating system 1 in the first embodiment, only the cup 2 showing an example of the arrangement of the sensor 40 and the control device 6A of the movement mechanism 6 are shown, and the same or corresponding configurations are denoted by the same reference numerals and description thereof will be omitted. Note that in Fig. 12, the shape of the cup 2 as viewed from the opening 8 side is shown.

[0095] In particular, in the case of articulated robot 20 having a cantilever structure, the positioning accuracy of arm 21 may not be sufficient to position cup 2. Also, when there is a large error in the fixed positions of object O and cup 2, cup 2 may not be able to be positioned with sufficient accuracy.

[0096] Therefore, the sensor 40 can be used to correct the relative position of the cup 2 with respect to the head H of the fastener F. Examples of practical sensors 40 for position correction include an optical camera 40A and a distance sensor 40B. By using the optical camera 40A, it is possible to photograph the head H of the fastener F to obtain image data, extract the contour of the head H of the fastener F by performing image recognition processing on the obtained image data, and two-dimensionally determine the center position of the head H of the fastener F based on the extracted contour of the head H of the fastener F.

[0097] On the other hand, if three or more distance sensors 40B are used, the 3D position of the object can in principle be determined by measuring the distance from each distance sensor 40B to the object. Alternatively, if two or more optical cameras 40A acquire two frames of image data that capture the head H of the fastener F, the 3D position including the distance to the head H of the fastener F can be geometrically determined based on the difference between the frames.

[0098] If the contour and 2D position of the center of the head H of fastener F can be detected, the 2D position of cup 2 can be corrected so that the center position of the opening 8 of cup 2 and the center position of the head H of fastener F are on the same straight line parallel to the longitudinal direction of fastener F in a plane perpendicular to the longitudinal direction of fastener F.

[0099] On the other hand, if the contour and 3D position of the center of head H of fastener F can be detected, it becomes possible to correct not only the 2D position of cup 2 in a plane perpendicular to the longitudinal direction of fastener F, but also the orientation of cup 2. In other words, the orientation of cup 2 can be corrected so that the plane on which the edge of cup 2 lies and the surface of object O are parallel to each other.

[0100] Therefore, the position of the cup 2 can be corrected by arranging the number and type of sensors 40 at appropriate positions according to the target positioning accuracy of the cup 2. Since the sensor 40 can convert the coordinates of the measurement data when the head H of the fastener F is within the field of view, the sensor 40 may be arranged at a desired portion of the moving mechanism 6 that does not move relative to the cup 2, such as the arm 21 or end effector 23 of the articulated robot 20, or may be arranged at a desired portion that does not move relative to the cup 2, such as outside the moving mechanism 6.

[0101] 12, one optical camera 40A and three distance sensors 40B arranged at equal intervals are attached to the outer periphery of a cup 2, which has a sponge 33 attached to its rim as a packing. This makes it possible to correct the 3D position of the cup 2, including its orientation. Specifically, the center position of the head H of the fastener F is obtained two-dimensionally based on an image of the head H of the fastener F captured by the optical camera 40A, and the control device 6A controls the moving mechanism 6 so that the distances from the obtained center position of the head H of the fastener F to the three distance sensors 40B are equal, thereby making it possible to correct the 3D position of the cup 2, including its orientation.

[0102] Of course, when the distance sensors 40B are arranged at unequal intervals, the control device 6A can control the moving mechanism 6 so that the distance from the center position of the head H of the fastener F to each distance sensor 40B becomes an ideal distance. Also, instead of the sponge 33, an O-ring 30 or other packing may be attached to the edge of the cup 2.

[0103] The function of acquiring measurement data such as image data and distance data from each sensor 40, processing the data, and generating a control signal for the movement mechanism 6 can be provided in the control device 6A.

[0104] According to the second embodiment described above, in addition to the same effects as those of the first embodiment, it is possible to obtain an effect that the positioning accuracy of the cup 2 can be improved.

[0105] (Third embodiment) FIG. 13 is a configuration diagram of an exhaust system 4 provided in a fastener coating system 1B according to a third embodiment of the present invention.

[0106] 13 differs from the fastener coating system 1 in the first embodiment and the fastener coating system 1A in the second embodiment in that a compressed air supply device 50 is connected to the atmospheric end of the air tube 13 that constitutes the exhaust system 4. Since other configurations and operations of the fastener coating system 1B in the third embodiment are not substantially different from those of the fastener coating system 1 in the first embodiment and the fastener coating system 1A in the second embodiment, only the configuration of the exhaust system 4 is shown, and the same or corresponding configurations are denoted by the same reference numerals and description thereof is omitted.

[0107] 13, one end of an air tube 13 constituting the exhaust system 4 is connected to the vent 2B of the cup 2, while the other end of the air tube 13, which is on the atmospheric side, can be connected to a compressed air supply device 50 in addition to a valve 14 such as a check valve 14A. The compressed air supply device 50 is a device that is provided with an opening / closing valve 52 at the outlet of a tank 51 that contains compressed air, so that a desired flow rate of compressed air can be supplied.

[0108] The opening / closing valve 52 of the compressed air supplying device 50 can be opened and closed at a desired timing by a control signal from the control device 6A of the moving mechanism 6. Therefore, the opening / closing valve 52 of the compressed air supplying device 50 can be opened and closed in conjunction with the operating state of the vacuum device 15.

[0109] If the compressed air supply device 50 is connected to the exhaust air tube 13, compressed air can be made to flow into the air tube 13 when the excess paint EP is discharged from the waste liquid port 2C of the cup 2. That is, while the vacuum device 15 is operating to suck the excess paint EP from inside the cup 2, the open / close valve 52 of the compressed air supply device 50 can be opened to supply compressed air into the air tube 13. Therefore, the excess paint EP that has entered the exhaust air tube 13 can be pushed out toward the waste liquid port 2C of the cup 2 by the compressed air.

[0110] Fig. 14 is a vertical cross-sectional view showing an example of the structure of a cup 2 provided in a fastener coating system 1B according to a third embodiment, Fig. 15 is a plan view of the cup 2 shown in Fig. 14, Fig. 16 is a cross-sectional view of the cup 2 at position AA shown in Fig. 15, and Fig. 17 is a perspective view of the cup 2 shown in Fig. 14. Note that in Figs. 14 to 17, illustrations of packings such as an O-ring 30 and a sponge 33 attached to the edge of the cup 2 are omitted.

[0111] When compressed air is supplied to the exhaust air tube 13 when discharging excess paint EP, the compressed air passes through the air tube 13 and the ventilation port 2B and flows into the gap 7 of the cup 2. Therefore, to prevent the compressed air from hitting the heads H of the fasteners F to which paint P is attached and causing uneven painting, the direction of the ventilation port 2B can be devised so that the compressed air flows along the wall surface within the gap 7.

[0112] 14 to 17, the direction and shape of the vent 2B can be determined so that the flow line of the compressed air flowing through the vent 2B opening in the gap 7 of the cup 2 does not point toward the head H of the fastener F. To achieve this, the direction and shape of the vent 2B can be determined so that the tangent to the inner wall of the vent 2B does not point toward the center of the gap 7 where the head H of the fastener F is placed.

[0113] 14 to 17, the vent 2B branches into two in the outer wall of the cup 2, and a single vent 2B opens on the outside of the cup 2 so that the air tube 13 can be connected, while two vents 2B open on the inside of the cup 2. The central axes of the two vents 2B opening on the inside of the cup 2 are generally oriented in the tangent direction of the wall surface forming the gap 7 in the cup 2. For this reason, as exemplified in FIG. 17, the compressed air can flow along the wall surface forming the gap 7 in the cup 2. As a result, it is possible to prevent the occurrence of uneven coating caused by the supply of compressed air.

[0114] According to the above-described third embodiment, in addition to the same effects as those of the first or second embodiment, it is possible to obtain the effect of efficiently discharging excess paint EP that has entered the exhaust air tube 13.

[0115] (Other embodiments) Although specific embodiments have been described above, the described embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein may be embodied in various other forms. In addition, various omissions, substitutions, and modifications may be made in the forms of the methods and apparatus described herein without departing from the spirit of the invention. The appended claims and their equivalents include such various forms and modifications as falling within the scope and spirit of the invention. [Explanation of symbols]

[0116] 1, 1A, 1B...fastener coating system, 2...cup, 2A...supply port, 2B...vent, 2C...waste port, 3...supply system, 4...exhaust system, 5...waste system, 6...movement mechanism, 6A...control device, 6B...storage device, 7...gap, 8...opening, 9...syringe, 10...plunger, 11...dispenser, 12...air tube, 13...air tube, 14...valve, 14A...check valve, 15...vacuum device, 16...waste trap, 17...waste ch tube, 18...air tube, 20...articulated robot, 21...arm, 22...holder, 23...end effector, 24...flange, 25...force sensor, 26...robot control device, 30...O-ring, 31...groove, 31A...recess, 32...wall surface, 33...sponge, 40...sensor, 40A...optical camera, 40B...distance sensor, 50...compressed air supply device, 51...tank, 52...opening / closing valve, O...object, F...fastener, H...head, P...paint, EP...surplus paint.

Claims

1. A fastener painting system for painting a head of a fastener attached to an object, comprising: a cup having a cavity for filling with paint and adapted to cover the head of the fastener by contacting the edge of the cup with the surface of the object; a supply system for storing paint and supplying the paint to the gap in the cup; a waste liquid system for draining excess paint from the cup within the gap; a moving mechanism for changing a relative position between the cup and the object; having A fastener coating system in which the cup is formed with a supply port for supplying the paint into the gap, an air vent for discharging air from within the gap, and a waste port for discharging excess paint from within the gap.

2. 2. A fastener coating system according to claim 1, wherein said cup has a ring-shaped elastic sponge attached to the rim thereof.

3. 3. A fastener painting system as described in claim 1 or 2, wherein, when the normal direction of the surface on which the edge of the cup lies is horizontal, the position of the air vent is determined so that the height of the air vent opening in the gap of the cup is the highest in the gap, while the position of the waste liquid port is determined so that the height of the waste liquid port opening in the gap of the cup is the lowest in the gap.

4. 4. A fastener painting system as claimed in any one of claims 1 to 3, wherein, when the normal direction of the plane on which the edge of the cup lies is horizontal, the wall surfaces of the gap are inclined so that the bottom of the gap is lower than the bottom of the opening of the cup, and the wall surfaces of the gap are inclined so that the top of the gap is higher than the top of the opening.

5. A fastener coating method for producing a coated article by coating the head of a fastener attached to an object, comprising the steps of: a step of changing a relative position between the object and a cup having a gap for filling with paint, the cup being formed with a supply port for supplying paint into the gap, an air vent for discharging air from the gap, and a waste liquid port for discharging excess paint from the gap, and covering the head of the fastener by bringing the edge of the cup into contact with the surface of the object; supplying the paint from the supply port into the gap while discharging air from the gap through the air vent; Discharging excess paint from the gap through the waste liquid outlet; A fastener coating method comprising the steps of:

Images