Sealant application device and method for manufacturing sealant-coated products

Abstract

To enable a more simple device and facility to perform cap sealing of a fastener using sealant whose viscosity and elasticity vary in a short time, stably and automatically, without deteriorating a quality.SOLUTION: A sealant coating device according to an embodiment coats a faster with sealant. The sealant coating device comprises a seal gun that discharges sealant toward the fastener through a nozzle, a distance meter, fixed to the nozzle, which measures a distance up to a surface of the sealant, a moving mechanism that moves the seal gun relatively with respect to the fastener, and a control device that controls the moving mechanism and the seal gun. The control device is configured to control the moving mechanism and the seal gun so that the faster is coated with the sealant under a coating condition for the sealant in accordance with the distance up to the surface of the sealant measured by the distance meter, while separating the nozzle from a surface of an object, after the seal gun has started to discharge the sealant.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a sealant application device and a method for manufacturing a sealant-coated product. [Background technology]

[0002] Conventionally, various sealant application devices that apply sealant to an object have been known (see, for example, Patent Document 1).As a specific example, a sealing system is known in which a rangefinder, a camera, and a force sensor are attached to a robot arm in addition to a nozzle for discharging sealant so that a dome-shaped sealant can be applied to the head of a fastener, and the rangefinder is used to measure the distance from the nozzle to the part, the camera is used to observe the amount and shape of the sealant, and the force sensor is used to detect that the nozzle has come into contact with the part, after which the nozzle is retracted to perform positioning of the nozzle (see, for example, Patent Document 2).

[0003] As another example, a sealant dispensing device has been proposed that includes a seal gun equipped with a nozzle for dispensing sealant, as well as a laser rangefinder attached to a robot arm, allowing the movement speed of the seal gun to be controlled based not only on the volume of the sealant but also on the amount of change in the volume of the sealant reservoir determined using the laser rangefinder (see, for example, Patent Document 3).

[0004] Similarly, a liquid application system has also been proposed in which a laser rangefinder is used to measure the thickness of a liquid such as a sealant that is dispensed onto a workpiece from the nozzle of a dispenser head attached to a robot arm as an end effector, and the dispenser head is moved by the robot arm according to the measurement results (see, for example, Patent Documents 4 and 5). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-050968 [Patent Document 2] Special Publication No. 2019-522564 [Patent Document 3] Japanese Patent Application Publication No. 2020-058990 [Patent Document 4] Japanese Patent Application Publication No. 2019-162613 [Patent Document 5] Japanese Patent Publication No. 2020-049641 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when conventional sealant applicators are used to cap fasteners with sealants whose viscosity and elasticity change over a short period of time, the quality of the cap seal can vary and other problems can occur due to the unstable amount of sealant dispensed.

[0007] Therefore, when using a sealant whose viscosity and elasticity change in a short period of time, it is possible to prevent variations in the quality and defects of the cap seal by suppressing the change in viscosity of the sealant. Factors that cause changes in the viscosity of the sealant include hardening due to the mixing of the two liquid components that make up the sealant, as well as changes in the surrounding environment such as temperature.

[0008] To suppress the effects of sealant hardening caused by mixing the two components, a two-component mixing mechanism can be installed in the seal gun and the components can be mixed just before the sealant is dispensed. However, this not only complicates the mechanism of the seal gun, increasing its weight, but also creating problems such as increased maintenance time.

[0009] On the other hand, in order to reduce environmental changes such as temperature changes, it is necessary to cover the entire sealant application device to manage air conditioning or to heat the sealant with a heater to keep the temperature of the sealant constant. However, this not only requires the installation cost of air conditioning equipment, but also poses the problem of the risk of the quality of the sealant deteriorating due to heating.

[0010] Given this background, cap sealing of fasteners using sealants whose viscosity and elasticity change in a short period of time often has to be performed manually by an operator, meaning that cap sealing of fasteners cannot be easily automated.

[0011] Therefore, the object of the present invention is to enable stable and automatic cap sealing of fasteners using sealants whose viscosity and elasticity change in a short period of time using simpler equipment and facilities without deteriorating quality. [Means for solving the problem]

[0012] A sealant applicator according to an embodiment of the present invention is an apparatus for applying sealant to a fastener fastened to an object. The sealant applicator includes a seal gun that dispenses sealant toward the fastener from a nozzle whose tip has a shape corresponding to the initial shape of the sealant after application to the fastener, a rangefinder fixed to the nozzle that measures the distance from a measurement position from the nozzle to the surface of the sealant dispensed to cover the fastener, a movement mechanism that moves the seal gun together with the rangefinder relative to the fastener, and a control device that controls the movement mechanism and the seal gun. The control device is configured to control the movement mechanism and the seal gun so that the nozzle is positioned to cover the fastener at a predetermined distance from the surface of the object and then, while moving the nozzle away from the surface of the object, the sealant is applied to the fastener under sealant application conditions corresponding to the distance to the surface of the sealant measured by the rangefinder. and determining a timing and a speed at which the movement mechanism starts moving to separate the nozzle from the surface of the object and a timing at which the discharge of the sealant from the seal gun is stopped based on the distance to the surface of the sealant measured by the distance meter. do. In addition, a sealant application device according to an embodiment of the present invention is a sealant application device that applies sealant to a fastener fastened to an object, and includes a seal gun that sprays the sealant toward the fastener from a nozzle whose tip has a shape that corresponds to the initial shape of the sealant after it has been applied to the fastener, a rangefinder that is fixed to the nozzle and measures the distance from a measurement position to the surface of the sealant that has been sprayed from the nozzle to cover the fastener, a moving mechanism that moves the seal gun together with the rangefinder relative to the fastener, and a control device that controls the moving mechanism and the seal gun. The control device is configured to control the moving mechanism and the seal gun so that after the nozzle has been positioned to cover the fastener at a position a predetermined distance from the surface of the object and the sealant has begun to be discharged from the seal gun, the nozzle is moved away from the surface of the object while the sealant is applied to the fastener under sealant application conditions that correspond to the distance to the surface of the sealant measured by the range finder, and to feedback-control the movement speed of the moving mechanism for moving the nozzle away from the surface of the object after the movement of the moving mechanism for moving the nozzle away from the surface of the object has begun and the distance to the surface of the sealant measured by the range finder approaches the distance that corresponds to the ideal shape of the sealant after it has been applied to the fastener.

[0013] In addition, a method for manufacturing a sealant-coated product according to an embodiment of the present invention involves applying the sealant to the fastener using the sealant application device described above, thereby manufacturing a sealant-coated product that includes the cap-sealed fastener and the object. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a configuration diagram of a sealant application device according to an embodiment of the present invention. [Figure 2] 2 is a diagram showing an example of a fastener to which a sealant has been applied by the sealant application device shown in FIG. 1. [Figure 3] FIG. 2 is a diagram showing a detailed configuration example of the seal gun shown in FIG. 1. [Figure 4] 2 is a diagram showing a flow of applying a sealant to a fastener using the sealant application device shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealant application device and a method for manufacturing a sealant-coated product according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] (Configuration and function of sealant application device) FIG. 1 is a configuration diagram of a sealant applicator according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a fastener to which sealant has been applied by the sealant applicator shown in FIG.

[0017] The sealant application device 1 is a device that applies sealant S to a fastener F fastened to an object O. As illustrated in FIG. 2 , when a fastener F such as a bolt or rivet is inserted into a through-hole provided in the object O to connect the object O, which is made up of multiple parts, a portion of the fastener F, including a nut, protrudes from the object O. Because there is a small gap between the fastener F and the object O and the portion of the fastener F protruding from the object O is not usually coated with paint for purposes such as rust prevention, it may be necessary to cover the portion of the fastener F protruding from the object O with sealant S. In particular, when the object O is an aircraft part, it is often necessary to cover the portion of the fastener F protruding from the object O with sealant S.

[0018] The process of sealing the gap between an object O and a fastener F with sealant S is called cap sealing or cap seal. In addition, the dome- or bell-shaped sealant S applied to seal the gap between an object O and a fastener F is also called a cap seal.

[0019] The sealant application device 1 can be composed of a seal gun 2 that dispenses sealant S toward a fastener F, a movement mechanism 3 that moves the seal gun 2 relative to the fastener F, and a control device 4. The seal gun 2 is a sealant S dispensing device that has a nozzle 5 for dispensing sealant S toward the fastener F and a dispenser 6 for supplying sealant S to the nozzle 5.

[0020] 1, it is practical to use an articulated robot 3A having an arm as the moving mechanism 3 for reasons of ease of installation and cost. When the moving mechanism 3 is an articulated robot 3A, a seal gun 2 can be attached as an end effector to the tip of the arm of the articulated robot 3A.

[0021] However, the movement mechanism 3 may be configured using desired mechanical elements such as gears, ball screws, caterpillars, cylinder mechanisms, wheels, rollers, etc., which move in parallel in three orthogonal axial directions or rotate around a desired rotation axis. In other words, the seal gun 2 may be moved by a gantry.

[0022] The moving mechanism 3 can be provided with a force sensor 3B for detecting when the tip of the nozzle 5 comes into contact with the surface of the object O. A typical commercially available articulated robot 3A can be optionally equipped with a force sensor 3B that measures pressure in three orthogonal axis directions and moments around three orthogonal axes.

[0023] The control device 4 is composed of an electric circuit such as a computer that controls the moving mechanism 3 and the seal gun 2. However, if the control system of the moving mechanism 3 and the seal gun 2 is not electric but pneumatic or hydraulic, a pneumatic circuit or hydraulic circuit may be used to configure part of the control device 4.

[0024] FIG. 3 is a diagram showing a detailed configuration example of the seal gun 2 shown in FIG.

[0025] 3 shows an example of the configuration of an electric servo seal gun 2. As described above, the seal gun 2 has the nozzle 5 and the dispenser 6. The outlet of the dispenser 6 is connected to the inlet of the nozzle 5.

[0026] The shape of the tip of the nozzle 5, which forms the outlet of the nozzle 5, corresponds to the initial shape of the sealant S after it has been applied to the fastener F. Specifically, the shape of the tip of the nozzle 5 is such that the inner diameter gradually increases toward the open end, so that the sealant S can be applied in a dome or bell shape to the head or nut side of the fastener F while leaving a gap between the tip of the nozzle 5 and the surface of the object O and covering the head or nut side of the fastener F.

[0027] The nozzle 5 has an inner diameter that gradually increases toward the open end, and the space inside the nozzle 5 can be filled with the sealant S. In other words, the nozzle 5 has a space at its tip that can be filled with the sealant S while partially covering the head and nut side of the fastener F without sealing it.

[0028] After the sealant S is applied to the fastener F by filling the space formed at the tip of the nozzle 5 with the sealant S, the nozzle 5 is retracted from the fastener F. When the nozzle 5 is retracted, the sealant S applied to the fastener F deforms into a shape according to the viscosity of the sealant S. Therefore, although the shape of the space formed at the tip of the nozzle 5 corresponds to the initial shape of the sealant S after application to the fastener F, it does not match the initial shape of the sealant S after the retraction of the nozzle 5 is completely completed, nor does it match the shape of the sealant S after the retraction of the nozzle 5 begins.

[0029] In the illustrated example, the inner surface of the space formed at the tip of the nozzle 5 has a simple truncated cone shape so that the sealant S can be applied to the portion of the fastener F protruding from the object O in a generally dome- or bell-shaped cap seal as shown in Fig. 2. In other words, the inner surface at the tip of the nozzle 5 tapers so that the inner diameter gradually increases toward the open end.

[0030] The dispenser 6 is a device that supplies the sealant S into the nozzle 5 as described above. The dispenser 6 can be configured, for example, to push the sealant S stored in the cartridge 10 to the inlet of the nozzle 5 by pressing a pusher 9 fixed to the tip of a rod 8 that is extendable by an actuator 7 against a cartridge 10. The actuator 7 that extends and retracts the rod 8 can be configured with a ball screw 12 that rotates by receiving power from a motor 11. Note that in the example shown in FIG. 3, torque output from the output shaft of the motor 11 is configured to be transmitted to the ball screw 12 by a pulley 13 and a power transmission belt 14, but a gear may also be used.

[0031] A laser rangefinder 15 is also fixed to the nozzle 5. The laser rangefinder 15 is a measuring instrument that detects the distance from a measurement position of the laser rangefinder 15, such as the emission position or reception position of the laser light L, to the reflection position by irradiating the laser light L and receiving the reflected laser light L. For this reason, the laser rangefinder 15 is composed of a light-emitting element that emits laser light L, such as a semiconductor laser, and a light-receiving element for the laser light L. A typical light-receiving element of the laser rangefinder 15 is a complementary metal oxide semiconductor (CMOS) sensor or a charge coupled device (CCD) sensor.

[0032] Laser rangefinder 15 is positioned to measure the distance from the measurement position to the surface of sealant S dispensed from nozzle 5 to cover fastener F while avoiding interference with nozzle 5. More specifically, laser rangefinder 15 is positioned to measure the distance to the surface of sealant S leaking from the gap between the tip of nozzle 5 and the surface of object O after sealant S is dispensed toward fastener F with a gap between the tip of nozzle 5 and the surface of object O.

[0033] Therefore, both the emitted laser light L and the reflected laser light L are inclined with respect to both the longitudinal direction of the nozzle 5 and the surface of the object O. Furthermore, even if there is a small gap between the tip of the nozzle 5 and the surface of the object O, the optical axes of the laser light L emitted from the laser rangefinder 15 and the laser light L reflected by the surface of the sealant S are positioned so as to pass near the edge of the nozzle 5, so that the laser light L can be irradiated onto and reflected by the surface of the sealant S immediately after it leaks out from the gap.

[0034] Conversely, the external shape of the nozzle 5 is also determined so as not to interfere with either the laser light L emitted from the laser rangefinder 15 or the laser light L reflected on the surface of the sealant S. In other words, the shape of the nozzle 5 is determined so as not only to be able to apply sealant S in a dome or bell shape to the head or nut side of the fastener F while covering the head or nut side of the fastener F, but also so as not to interfere with either the laser light L emitted from the laser rangefinder 15 or the laser light L reflected on the surface of the sealant S.

[0035] The sealant S dispensed toward the fastener F spreads in a generally circular shape when viewed from the direction of dispensing the sealant S. Therefore, it is considered that the spreading speed of the sealant S is easier to observe at the diameter portion of the circular base of the sealant S, which is filled in the nozzle 5 in a generally truncated cone or bell shape.

[0036] Therefore, the laser rangefinder 15 can be placed at a position on a plane including the central axis AX of the nozzle 5 where it can measure the distance from the measurement position to the surface of the sealant S. In other words, the laser rangefinder 15 can be positioned so that the optical axis of the laser light L emitted from the laser rangefinder 15 and the optical axis of the laser light L received by the laser rangefinder 15 both intersect with the central axis AX of the nozzle 5. This makes it easy to observe the displacement of the surface position of the sealant S with the laser rangefinder 15.

[0037] After the sealant S has been filled into the nozzle 5, the movement mechanism 3 is driven to move the seal gun 2 including the nozzle 5 away from the object O and the fastener F. Therefore, the laser rangefinder 15 fixed to the nozzle 5 is also moved away from the object O and the fastener F together with the seal gun 2. In other words, the laser rangefinder 15, together with the seal gun 2, is moved relative to the object O and the fastener F by the movement mechanism 3.

[0038] While the nozzle 5 is being pulled away from the object O, the laser rangefinder 15 successively measures the distance to the surface of the sealant S, which is becoming roughly dome-shaped or bell-shaped. The measurement results of the distance to the surface of the sealant S obtained by the laser rangefinder 15 are sequentially output as time-series data to the control device 4. In other words, the laser rangefinder 15 outputs to the control device 4 the change in the distance from the laser rangefinder 15 to the surface of the sealant S over time.

[0039] On the other hand, the control device 4 is configured to perform overall control of the moving mechanism 3 and the seal gun 2 based on the distance to the surface of the sealant S measured by the laser rangefinder 15. That is, the control device 4 is configured to control the moving mechanism 3 to position the seal gun 2 relative to the object O and fastener F and to control the seal gun 2 to start discharging the sealant S, and also to control the moving mechanism 3 to move the seal gun 2 away from the object O and fastener F and to stop discharging the sealant S based on the distance from the laser rangefinder 15 to the surface of the sealant S measured by the laser rangefinder 15.

[0040] More specifically, the control device 4 is configured to control the moving mechanism 3 and the seal gun 2 so that after the nozzle 5 has been positioned to cover the fastener F at a position a predetermined distance from the surface of the object O and the sealant S has begun to be discharged from the seal gun 2, the nozzle 5 is pulled away from the surface of the object O and the sealant S is applied to the fastener F under application conditions for the sealant S that correspond to the distance from the laser rangefinder 15 to the surface of the sealant S measured by the laser rangefinder 15.

[0041] The application conditions of the sealant S that can be determined by the control device 4 based on the distance from the laser rangefinder 15 to the surface of the sealant S include conditions that affect the shape of the sealant S after application, such as the start timing and speed of the movement of the moving mechanism 3 to move the nozzle 5 away from the surface of the object O, the timing to stop the discharge of the sealant S from the seal gun 2, and the amount of sealant S discharged from the seal gun 2.

[0042] However, since a complex control mechanism and control processing are required to accurately control the amount of sealant S dispensed, whose viscosity and elasticity change in a short period of time, the control value for the amount of sealant S dispensed is kept constant, and the control target is narrowed down to the start timing and speed of the retraction movement of the nozzle 5 from the surface of the object O and the timing at which the dispense of sealant S from the seal gun 2 stops, which leads to simplification of control.

[0043] In this case, after the movement of the moving mechanism 3 for moving the nozzle 5 away from the surface of the object O is started, the movement speed of the moving mechanism 3 for moving the nozzle 5 away from the surface of the object O can be feedback-controlled by the control device 4 so that the distance measured by the laser rangefinder 15 from the laser rangefinder 15 to the surface of the sealant S approaches the distance corresponding to the ideal shape of the sealant S after it has been applied to the fastener F. Note that, although feedback control may be performed using the positions of the nozzle 5 and the moving mechanism 3 as control command values ​​instead of the movement speeds thereof, it is more practical to use the retraction speeds of the nozzle 5 and the moving mechanism 3 as control command values, as this simplifies the control signals.

[0044] (Sealant application method) Next, a method for applying sealant to fasteners F using the sealant application device 1 will be described.

[0045] FIG. 4 is a diagram showing a flow of applying sealant S to fastener F using sealant application device 1 shown in FIG.

[0046] First, in step S1, the seal gun 2 including the nozzle 5 is positioned to an initial position. Specifically, the seal gun 2 is positioned so that an appropriate gap is formed between the edge of the tip of the nozzle 5 and the surface of the object O. The distance between the tip of the nozzle 5 and the surface of the object O is determined to be a distance such that the nozzle 5 can be filled with sealant S while the fastener F to which the sealant S is to be applied is substantially covered by the nozzle 5, and such that some of the filled sealant S leaks out from the gap between the tip of the nozzle 5 and the surface of the object O.

[0047] Empirically, it is believed that if the distance between the tip of the nozzle 5 and the surface of the object O is between 0.5 mm and 5 mm, it will be possible to fill the sealant S inside the nozzle 5 and for an appropriate amount of sealant S to leak out of the nozzle 5.

[0048] The positioning of the seal gun 2 is performed by driving a movement mechanism 3, such as an articulated robot 3A, which moves the seal gun 2 under the control of a control device 4. The positioning of the seal gun 2 so that the tip of the nozzle 5 covers the fastener F to which the sealant S is to be applied can be performed by two-dimensionally positioning the seal gun 2 in a direction perpendicular to the central axis AX of the nozzle 5 and the length direction of the fastener F, and then one-dimensionally positioning the seal gun 2 in the central axis AX of the nozzle 5 and the length direction of the fastener F.

[0049] Two-dimensional positioning of the seal gun 2 in a direction perpendicular to the central axis AX of the nozzle 5 and the longitudinal direction of the fastener F can be achieved by first adjusting the orientation of the seal gun 2 so that the central axis AX of the nozzle 5 is parallel to the longitudinal direction of the fastener F, then bringing the seal gun 2 close to the object O, and then using the movement mechanism 3 to translate the seal gun 2 so that the central axis AX of the nozzle 5 and the central axis of the fastener F are on the same straight line. Alternatively, these movements may be performed simultaneously by the movement mechanism 3.

[0050] The accuracy required for two-dimensional positioning of the sealing gun 2 in a direction perpendicular to the central axis AX of the nozzle 5 and the length direction of the fastener F is usually rough because the viscous sealant S deforms. For this reason, two-dimensional positioning of the sealing gun 2 in a direction perpendicular to the central axis AX of the nozzle 5 and the length direction of the fastener F can be performed by installing a control program that defines the position of the fastener F in advance in the control device 4 and controlling the movement mechanism 3 with the control program.

[0051] Alternatively, the fastener F may be photographed with an image sensor such as an optical camera, and the control device 4 may automatically detect the center axis of the fastener F by performing image processing such as image recognition processing such as pattern matching processing or contour extraction processing. In this case, the necessary image sensor can be provided in an appropriate position.

[0052] On the other hand, the accuracy required for one-dimensional positioning of the seal gun 2 along the center axis AX of the nozzle 5 and the longitudinal direction of the fastener F is such that the distance between the tip of the nozzle 5 and the surface of the object O is on the order of millimeters, and therefore the influence of positioning errors on the jig or the like of the object O is often so high that it cannot be ignored.

[0053] Therefore, one-dimensional positioning of the seal gun 2 in the direction of the center axis AX of the nozzle 5 and the length of the fastener F can be achieved by driving the moving mechanism 3 to temporarily contact the tip of the nozzle 5 with the surface of the object O after two-dimensional positioning of the seal gun 2 in the direction perpendicular to the center axis AX of the nozzle 5 and the length of the fastener F has been completed, and then moving the tip of the nozzle 5 away from the surface of the object O by a predetermined distance.

[0054] Whether or not the tip of the nozzle 5 has come into contact with the surface of the object O can be detected by the force sensor 3B provided in the movement mechanism 3. That is, when the measured value of the pressure in the direction of the central axis AX of the nozzle 5 and the length of the fastener F output from the force sensor 3B exceeds a threshold value, it can be determined that the tip of the nozzle 5 has come into contact with the surface of the object O. Therefore, one-dimensional positioning of the sealing gun 2 can be performed by the control of the movement mechanism 3 by the control device 4 based on the measured value of the pressure in the direction of the central axis AX of the nozzle 5 and the length of the fastener F output from the force sensor 3B, in addition to the control program.

[0055] Alternatively, the distance to the surface of the object O may be measured by a laser rangefinder 15 fixed to the nozzle 5 or another rangefinder additionally provided to the nozzle 5, and the one-dimensional positioning of the seal gun 2 may be performed so that the distance between the tip of the nozzle 5 and the surface of the object O is a predetermined distance. In this case, the one-dimensional positioning of the seal gun 2 can be performed without bringing the tip of the nozzle 5 into contact with the surface of the object O.

[0056] Furthermore, a measured value of the distance to the surface of the object O is output to the control device 4 from a laser rangefinder 15 fixed to the nozzle 5 or from another rangefinder additionally provided to the nozzle 5. Then, one-dimensional positioning of the sealing gun 2 in the longitudinal direction of the central axis AX of the nozzle 5 and the fastener F is performed by controlling the movement mechanism 3 by the control device 4 based on the measured value of the distance between the tip of the nozzle 5 and the surface of the object O.

[0057] Once the three-dimensional positioning of the seal gun 2 including the nozzle 5 to the initial position is completed in this way, the discharge of the sealant S can be started in step S2. To this end, a control signal is output from the control device 4 to the dispenser 6 of the seal gun 2, and the sealant S is supplied from the dispenser 6 into the nozzle 5.

[0058] For example, if the seal gun 2 has the configuration shown in Fig. 3, a control signal is output from the control device 4 to the motor 11, causing the motor 11 to rotate. Then, torque output from the output shaft of the motor 11 is transmitted to the ball screw 12 via the pulley 13 and the power transmission belt 14. This causes the ball screw 12 to rotate, and the rod 8 fixed to the female thread fastened to the ball screw 12 moves toward the cartridge 10. As a result, the sealant S stored in the cartridge 10 is pushed into the nozzle 5 by the pusher 9 provided at the tip of the rod 8.

[0059] When the sealant S is supplied into the nozzle 5, the sealant S fills the space formed inside the nozzle 5, leaving a gap between the nozzle 5 and the surface of the object O. As a result, the sealant S is evenly applied to the fastener F. Furthermore, when the sealant S is supplied into the nozzle 5, some of the sealant S leaks out from the gap between the tip of the nozzle 5 and the surface of the object O.

[0060] When the sealant S leaks out of the nozzle 5, the laser light L transmitted and received between the laser rangefinder 15 and the surface of the object O is blocked by the sealant S. That is, the laser light L emitted from the laser rangefinder 15 is reflected by the surface of the sealant S. As a result, the distance measurement value by the laser rangefinder 15 decreases.

[0061] Therefore, the control device 4, which continuously acquires distance measurement values ​​from the laser rangefinder 15, can detect that the fastener F has been completely immersed in the sealant S as a result of the sealant S being filled into the nozzle 5. Specifically, by threshold processing in the control device 4 for the distance measurement values ​​acquired from the laser rangefinder 15, when the distance measurement value acquired from the laser rangefinder 15 becomes equal to or less than the threshold, it can automatically determine that the laser light L that was reflected from the surface of the object O has been reflected from the surface of the sealant S. In other words, the control device 4 can automatically detect that the filling of the sealant S into the nozzle 5 has been completed.

[0062] When the control device 4 detects leakage of the sealant S outside the nozzle 5 in this way, in step S3, the nozzle 5 starts to retract away from the object O and the fastener F. That is, the detection of leakage of the sealant S outside the nozzle 5 triggers the control device 4 to control the movement mechanism 3 and retract the seal gun 2 along the center axis AX of the nozzle 5 and in the longitudinal direction of the fastener F.

[0063] At the start of the retraction movement of the seal gun 2, the retraction movement of the seal gun 2 is performed at an initial speed that is empirically determined in advance. The initial speed of the retraction movement of the seal gun 2 can be defined in advance by the control program. Therefore, the control device 4 can output an initial value of the speed control signal to the movement mechanism 3 in accordance with the control program.

[0064] On the other hand, after the retraction movement of the seal gun 2 has begun, the movement mechanism 3 can be feedback-controlled by the control device 4 so as to minimize the deviation between the distance to the surface of the sealant S measured by the laser rangefinder 15 and the reference value defined in the control program.

[0065] Specifically, when the retraction movement of the seal gun 2 begins, the sealant S filled in the nozzle 5 is released into the atmosphere, causing a deformation of the shape of the sealant S. In addition, the distance measurement position of the laser rangefinder 15 fixed to the nozzle 5 gradually moves relative to the applied sealant S in a direction away from the surface of the object O.

[0066] Therefore, the deviation of the shape of the actual sealant S from the ideal shape of the sealant S after application to the fastener F, i.e., the cap seal, can be observed by the laser rangefinder 15. More specifically, based on the ideal shape of the cap seal, the ideal distance from the laser rangefinder 15 to the surface of the sealant S on the plane where the laser light L is transmitted and received can be uniquely determined. Therefore, the deviation of the shape of the actual sealant S from the ideal shape of the cap seal can be expressed using as an index the difference or ratio between the ideal distance from the laser rangefinder 15 to the surface of the sealant S on the plane where the laser light L is transmitted and received and the distance actually measured by the laser rangefinder 15.

[0067] Therefore, the ideal distance from the laser rangefinder 15 to the surface of the sealant S can be defined as a reference value in the control program, and the retraction speed or retraction position of the sealing gun 2 can be feedback-controlled so as to minimize the difference or ratio between the reference value defined in the control program and the measured value of the distance from the laser rangefinder 15 to the surface of the sealant S that is actually measured by the laser rangefinder 15. This allows the shape of the sealant S to approach the ideal shape.

[0068] When the discharge of the sealant S is stopped while the seal gun 2 is gradually retracted from the surface of the object O by such automatic control of the movement mechanism 3 by the control device 4, the sealant S adhering to the surface of the object O and the fastener F is separated from the sealant S in the nozzle 5 as shown in step S4 in a few seconds. In other words, due to the adhesive force of the sealant S, the sealant S is applied to the surface of the object O and the fastener F in a roughly dome- or bell-shaped pattern.

[0069] The laser range finder 15 can measure the distance to the surface of the sealant S immediately before it separates from the sealant S attached to the surface of the object O and the fastener F, as well as after it separates from the sealant S in the nozzle 5. Therefore, while measuring the distance to the surface of the sealant S immediately before it separates from the sealant S attached to the surface of the object O and the fastener F using the laser range finder 15, it is possible to predict the time when the sealant S attached to the surface of the object O and the fastener F will separate from the sealant S in the nozzle 5, and automatically stop discharging the sealant S.

[0070] Specifically, the relationship between the appropriate timing to stop dispensing the sealant S and the distance from the laser rangefinder 15 to the surface of the sealant S can be empirically determined and defined in the control program. As a result, when the distance from the laser rangefinder 15 to the surface of the sealant S reaches the distance defined in the control program, the dispenser 6 can be automatically controlled by the control device 4 to stop dispensing the sealant S.

[0071] For example, if the seal gun 2 has the configuration illustrated in Fig. 3, the control device 4 can output a control signal to the motor 11 to stop the rotation of the motor 11. This can stop the discharge of the sealant S from the dispenser 6 and the seal gun 2.

[0072] In this way, the sealing gun 2 can be retracted and the discharge of the sealant S can be stopped while the application state of the sealant S is being observed with the laser rangefinder 15. Then, when the application of the sealant S to the fastener F by the sealant application device 1 is completed, a sealant-applied product can be manufactured that includes the cap-sealed fastener F and the object O.

[0073] (effect) The sealant application device 1 and the method for manufacturing a sealant-coated product described above measure the distance to the surface of the sealant S using a laser rangefinder 15, and based on the measured distance to the surface of the sealant S, the application conditions of the sealant S, such as the retraction speed of the seal gun 2 and the timing to stop discharging the sealant S, are controlled in real time.

[0074] Therefore, with the sealant application device 1 and the method for manufacturing sealant-applied products, it is possible to stably and automatically seal the cap of fasteners F using sealant S, whose viscosity and elasticity change in a short period of time, using simpler equipment and facilities without degrading quality.

[0075] That is, even if the viscosity or elasticity of the sealant S changes during cap sealing of the fastener F and the amount of sealant S dispensed from the nozzle 5 becomes unstable, the nozzle 5 can be retracted from the fastener F at a timing and speed that corresponds to the surface position of the sealant S, or the dispense of the sealant S can be stopped. This makes it possible to apply the sealant S to the fastener F in a more appropriate shape. In other words, it is possible to perform high-quality cap sealing of the fastener F.

[0076] Moreover, because the sealant S can be stably applied to the fastener F even if the viscosity or elasticity of the sealant S changes, even when the sealant S is prepared by mixing two components, there is no need to provide the seal gun 2 with a mechanism for mixing the two components. As a result, not only can the configuration of the seal gun 2 be prevented from becoming complicated, but maintenance of the seal gun 2 is also simplified. In addition, there is no need for equipment such as heaters or air conditioning equipment to delay the hardening of the sealant S.

[0077] (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 a variety of other forms. Furthermore, 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 all such forms and modifications as fall within the scope and spirit of the invention.

[0078] For example, in the above-described embodiment, an example was described in which the laser rangefinder 15 was used to measure the distance to the surface of the sealant S, but the distance to the surface of the sealant S can be measured using any desired rangefinder, such as an ultrasonic rangefinder, instead of the laser rangefinder 15. [Explanation of symbols]

[0079] 1. Sealant application device 2 Seal Gun 3 Moving mechanism 3A Articulated Robot 3B Force Sensor 4. Control device 5 nozzles 6 Dispenser 7 Actuators 8 rods 9 Pusher 10 cartridges 11 Motor 12 Ball screw 13 Pulley 14 Power transmission belt 15 Laser rangefinder AX Nozzle central axis F fastener L laser light O Object S sealant

Claims

1. A sealant application device that applies sealant to a fastener fastened to an object, a seal gun that ejects the sealant toward the fastener from a nozzle whose tip shape corresponds to the initial shape of the sealant after it has been applied to the fastener; a distance meter fixed to the nozzle and configured to measure a distance from a measurement position to a surface of the sealant dispensed from the nozzle to cover the fastener; a movement mechanism that moves the seal gun together with the range finder relative to the fastener; a control device that controls the moving mechanism and the seal gun; Equipped with The control device is configured to control the movement mechanism and the seal gun so that after the nozzle has been positioned to cover the fastener at a position a predetermined distance from the surface of the object and the sealant has started to be discharged from the seal gun, the control device moves the nozzle away from the surface of the object and controls the movement mechanism and the seal gun so that the sealant is applied to the fastener under sealant application conditions that correspond to the distance to the sealant surface measured by the range finder, and to determine the start timing and speed of movement of the movement mechanism to move the nozzle away from the surface of the object and the timing to stop discharging the sealant from the seal gun based on the distance to the sealant surface measured by the range finder.

2. 2. The sealant application device of claim 1, wherein the control device is configured to feedback-control the movement speed of the movement mechanism for moving the nozzle away from the surface of the object so that, after movement of the movement mechanism for moving the nozzle away from the surface of the object is started, the distance to the surface of the sealant measured by the range finder approaches a distance corresponding to an ideal shape of the sealant after it has been applied to the fastener.

3. A sealant application device that applies a sealant to a fastener fastened to an object, a seal gun that ejects the sealant toward the fastener from a nozzle whose tip shape corresponds to the initial shape of the sealant after it has been applied to the fastener; a distance meter fixed to the nozzle and configured to measure a distance from a measurement position to a surface of the sealant dispensed from the nozzle to cover the fastener; a movement mechanism that moves the seal gun together with the range finder relative to the fastener; a control device that controls the moving mechanism and the seal gun; Equipped with The control device is configured to control the moving mechanism and the seal gun so that after the nozzle has started to discharge the sealant from the seal gun with the nozzle positioned to cover the fastener at a position a predetermined distance from the surface of the object, the control device moves the nozzle away from the surface of the object while controlling the movement mechanism and the seal gun so that the sealant is applied to the fastener under sealant application conditions that correspond to the distance to the surface of the sealant measured by the rangefinder, and after the movement of the moving mechanism has started to move the nozzle away from the surface of the object, the control device is configured to feedback-control the movement speed of the moving mechanism to move the nozzle away from the surface of the object so that the distance to the surface of the sealant measured by the rangefinder approaches the distance that corresponds to the ideal shape of the sealant after it has been applied to the fastener.

4. The sealant applicator according to claim 1 , wherein the distance meter is disposed at a position on a plane including a central axis of the nozzle where the distance from the measurement position to a surface of the sealant can be measured.

5. A method for manufacturing a sealant-coated product, which produces a sealant-coated product including the cap-sealed fastener and the object by applying the sealant to the fastener using the sealant application device described in any one of claims 1 to 4.

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