Coating apparatus

Abstract

To detect collision of a coating gun with an object to be coated, at low cost with high accuracy.SOLUTION: A coating apparatus is provided with: a plurality of coating guns 35 that discharge powdered coating materials P toward an object to be coated W; a driving device 20 that moves the plurality of coating guns 35 in a synchronized state; a plurality of acceleration sensors 41, provided in the plurality of coating guns 35 respectively, which respectively detect impact acting on the plurality of coating guns 35; and a determining part 40 that determines that the coating guns 35 have collided with the object to be coated W, when a differential value in detected values by the acceleration sensors 41 between the two coating guns 35 exceeds a threshold.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a coating device. [Background technology]

[0002] Patent Document 1 discloses a coating device that sprays powder paint discharged from a coating gun onto an object to be coated that is being transported by a conveyor. In this device, the size and shape of the object to be coated are detected immediately before the object enters the coating booth, and a detection signal is sent to a control device. The control device controls the amount of powder paint discharged from the coating gun based on the transmitted detection signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-156488 A Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of painting device, there is a concern that the paint gun may collide with the workpiece when the orientation of the workpiece suspended from the connector changes, but it is possible to detect the collision by attaching an acceleration sensor to the paint gun. However, if the paint gun is attached to the end of an arm that repeatedly rises and falls using a reciprocator, the arm bends and the paint gun swings when switching between the rising and lowering motions. Therefore, there is a concern that the acceleration sensor may detect the swing of the paint gun and erroneously detect that the paint gun has collided with the workpiece even if the painting operation of the paint gun is normal. To address this issue, it is possible to determine whether the state is normal by performing FFT (fast Fourier transform) analysis using an A / D converter, FPGA (field-programmable gate array), or microcomputer, but the A / D converter, FPGA, and microcomputer required for FFT analysis are expensive.

[0005] The present invention was developed in view of the above circumstances, and an object of the present invention is to make it possible to detect a collision between a paint gun and an object to be painted inexpensively and with high accuracy. [Means for solving the problem]

[0006] The present disclosure relates to A plurality of paint guns that spray paint toward the object to be painted; A drive device that moves the plurality of paint guns in a synchronized state; a plurality of acceleration sensors provided on the plurality of paint guns, each of which detects an impact acting on the plurality of paint guns; and a judgment unit that judges that the workpiece has collided with the paint gun when a difference value of the detection value of the acceleration sensor between the two paint guns exceeds a threshold value. Effect of the Invention

[0007] According to this configuration, a collision between the paint gun and the workpiece can be detected inexpensively and with high accuracy. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a driving device constituting the coating device of the first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a block diagram showing a configuration of a determination unit according to the first embodiment. [Figure 4] FIG. 11 is a block diagram showing the configuration of a determination unit according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. Any combination of the following embodiments without causing any contradiction is also included in the embodiments for carrying out the present invention. The coating device of the present disclosure is (1) A coating apparatus includes a plurality of coating guns that eject paint toward a coating object, a driving device that moves the plurality of coating guns in a synchronized state, a plurality of acceleration sensors that are individually provided on the plurality of coating guns and individually detect impacts acting on the plurality of coating guns, and a determination unit that determines that the coating guns have collided with the coating object when a difference value between the detection values ​​of the acceleration sensors between the two coating guns exceeds a threshold value. According to the configuration of the present disclosure, when a coating gun collides with a coating object, the difference between the detection value by the acceleration sensor of the colliding coating gun and the detection value by the acceleration sensor of the non-colliding coating gun becomes large. When the difference value between the detection values ​​exceeds a threshold value, the determination unit determines that the coating gun has collided with the coating object. In determining whether or not a collision has occurred, advanced processing such as FFT analysis is not required. According to the present disclosure, a collision between a coating gun and a coating object can be detected inexpensively and with high accuracy.

[0010] (2) It is preferable that the apparatus includes a conveyor for transporting the workpiece, the drive device includes a reciprocator for reciprocating the multiple paint guns in a direction intersecting the conveying direction of the conveyor at a speed faster than the conveying speed of the conveyor, and the acceleration sensor detects acceleration in a direction parallel to the moving direction of the reciprocator. With this configuration, the acceleration at the time of collision is greater when the paint gun collides with the workpiece parallel to the moving direction of the reciprocator than when the paint gun collides with the workpiece parallel to the conveying direction of the conveyor. Therefore, it is possible to reliably detect a collision between the paint gun and the workpiece.

[0011] (3) In (2), it is preferable that the reciprocator has a plurality of elastically deformable arms that protrude toward the workpiece, and the plurality of paint guns are individually attached to the protruding ends of the plurality of arms. According to this configuration, if the impact of a collision is small and the collision is not detected, the reciprocator continues to be driven after the collision, causing the arms to elastically deform, and then the paint guns come off the workpiece. When the paint guns come off the workpiece, a large acceleration is generated by the elastic restoring force of the arms, so that the collision between the paint guns and the workpiece can be reliably detected.

[0012] (4) In (2) or (3), it is preferable that the multiple paint guns are supported by the reciprocator with a gap between them parallel to the drive direction of the reciprocator, and the two paint guns to be judged by the judgement unit are arranged with a gap between them in the drive direction of the reciprocator. With this configuration, only one of the two paint guns to be judged will collide with the workpiece, so there will always be a difference in the detection value of the acceleration sensor between the two paint guns. Therefore, a collision can be reliably detected.

[0013] <Example 1> A first embodiment of the present invention will be described below with reference to Figs. 1 to 3. The present invention is not limited to these examples, but is defined by the claims, and includes all modifications within the meaning and scope equivalent to the claims. In this first embodiment, the F direction in Figs. 1 and 2 is defined as the front with respect to the front-rear direction. The H direction in Fig. 1 is defined as the up-down direction. The R direction in Fig. 2 is defined as the right with respect to the left-right direction.

[0014] The coating apparatus of the present embodiment 1 is an apparatus for performing electrostatic powder coating on a workpiece W. The coating apparatus is configured to include a conveyor 10 for transporting the workpiece W, four (or a plurality of) coating guns 35 for discharging powder coating material P (powder coating material P as described in the claims) toward the workpiece W, a drive unit 20 for driving the four coating guns 35 in a synchronized state, a determination unit 40 for determining whether the coating guns 35 have collided with the workpiece W, and a control unit 45 for controlling the operation of the conveyor 10 and the drive unit 20 based on the determination result of the determination unit 40.

[0015] The conveyor 10 is configured to include a guide rail 11 arranged to extend horizontally, a plurality of hangers 12 arranged at intervals on the guide rail 11, and a conveyor drive unit 13 (see FIG. 3) that moves the plurality of hangers 12 along the guide rail 11. An object W to be coated is hung from each hanger 12. The object W to be coated is designed to be transported while hung from the hanger 12. The object W to be coated has a shape (for example, a box shape with an open rear) having an uneven portion on the surface facing the reciprocator 22. A shape detection booth (not shown) is provided in the middle of the transport path of the object W to be coated. In the shape detection booth, the shape of the transported object W to be coated is detected by a shape detection device (not shown). A coating booth is provided downstream of the shape detection booth in the transport path of the object W in the transport direction. The transport direction of the conveyor 10 in the coating booth (the direction in which the object W moves) is to the right.

[0016] In the painting booth, a driving device 20 is provided so as to face the conveyor 10 from the rear. As shown in FIG. 1, the driving device 20 includes a base member 21, a reciprocator 22, and four painting guns 35. The base member 21 is installed on the floor surface of the painting booth. The base member 21 is provided with a position adjustment mechanism (not shown) for adjusting the position of the reciprocator 22 relative to the base member 21 in the front-rear direction (the direction approaching or moving away from the conveyor 10). The reciprocator 22 includes a housing 23, a lifting mechanism 24 provided in the housing 23, four arms 33, and four painting guns 35.

[0017] The lifting mechanism 24 has a reciprocator drive unit 25 disposed at the lower end of the housing 23, a driven gear 28 disposed at the upper end of the housing 23, and an endless chain 29. The reciprocator drive unit 25 has a drive motor 26 with a reducer and a drive gear 27 fixed to the output shaft of the drive motor 26. The endless chain 29 is stretched between the drive gear 27 and the driven gear 28, and is driven by the drive motor 26 to run in both forward and reverse directions. A pair of upper and lower support members 30 elongated in the left-right direction are fixed to a portion of the endless chain 29 that is arranged in the vertical direction. The left end of the pair of support members 30 protrudes to the outside of the housing 23. A connecting member 31 elongated in the vertical direction is fixed to the left end of the pair of support members 30. Four forward and backward drive members 32 spaced apart in the vertical direction are fixed to the connecting member 31.

[0018] A rear end of an arm 33 elongated in the front-rear direction is attached to each of the forward / rear driving members 32. The arm 33 is made of fiber-reinforced plastic (FRP) and has a long cylindrical shape. The length of the arm 33 is, for example, about 1.2 m to 1.5 m. The outer diameter of the arm 33 is, for example, about 40 mm. When an external force is applied to the arm 33, the arm 33 is elastically deformed in such a manner that its axis in the front-rear direction is curved. The four arms 33 extend forward from the forward / rear driving member 32 toward the conveyor 10 (the workpiece W). The four arms 33 are individually driven to advance and retreat in the front-rear direction by the forward / rear driving member 32. The vertical movement speed in the front-rear direction by the forward / rear driving member 32 is faster than the conveying speed by the conveyor 10. A coating gun 35 is attached to the front end of each arm 33.

[0019] Based on the three-dimensional data of the shape of the workpiece W obtained in the shape detection booth, the drive device 20 moves the four arms 33 and the four paint guns 35 in two-dimensional directions in accordance with the shape of the workpiece W. That is, the four arms 33 and the four paint guns 35 are moved in the vertical direction by the lifting mechanism 24 of the reciprocator 22, and are moved in the front-rear direction by the forward / retract drive member 32, while discharging the powder paint P toward the workpiece W. The vertical lifting speed by the reciprocator 22 is faster than the transport speed by the conveyor 10.

[0020] While the paint guns 35 are discharging the powder paint P, the four paint guns 35 are driven to move up and down synchronously. Here, the four paint guns 35 being driven to move up and down synchronously is defined as the four paint guns 35 moving back and forth integrally in the up and down direction. The four paint guns 35 are allowed to move individually in the front and back direction independently of the other paint guns 35 by the forward and backward drive members 32, but the form in which the four paint guns 35 are driven to move up and down synchronously also includes a form in which the four paint guns 35 move individually back and forth.

[0021] The paint gun 35 has a body 36 made of an insulating material that houses a high-voltage generator (not shown). A nozzle 37 that discharges powder paint P charged by the high-voltage generator is provided at the front end of the body 36. A powder paint P hose (not shown) for supplying powder paint P to a powder paint P supply path (not shown) in the body 36 and a power supply cable (not shown) for supplying power to the high-voltage generator are connected to the paint gun 35.

[0022] As shown in FIG. 3, the determination unit 40 includes four acceleration sensors 41, a differential amplifier circuit 42, a threshold adjustment unit 43, and a comparator 44. The four acceleration sensors 41 are attached to each of the paint guns 35. The acceleration sensors 41 are housed inside the body 36 of the paint guns 35 and move integrally with the paint guns 35. The acceleration sensors 41 are analog sensors using piezoelectric elements and detect acceleration in three dimensional directions (up and down, front and back, and left and right) that occur in the paint guns 35. The acceleration sensor 41 detects the speed change as acceleration when the paint guns 35 start moving instantaneously, stop moving instantaneously, or change the moving direction of the paint guns 35 instantaneously. The acceleration detected by each acceleration sensor 41 is input to a differential amplifier circuit 42. The four detection signals amplified in the differential amplifier circuit 42 are input to a comparator 44.

[0023] The comparator 44 is mainly composed of a microcomputer and has a CPU (not shown) and a storage unit (not shown). The comparator 44 stores a program for calculating the difference between the detection values ​​of the two acceleration sensors 41, a program for comparing the calculated difference with a preset threshold value, and a program for determining the presence or absence of a collision between the paint gun 35 and the workpiece W based on the comparison result between the difference and the threshold value, as described below. In the comparator 44, the acceleration sensor 41 of the paint gun 35 located at the top of the four paint guns 35 is set as "acceleration sensor A", and the following are set as "acceleration sensor B" and "acceleration sensor C" from the top, and the acceleration sensor 41 of the paint gun 35 located at the bottom is set as "acceleration sensor D". In the comparator 44, four types of detection units, namely, first to fourth types, are further set. In the first detection unit, the acceleration sensor A is set as a reference sensor, and the acceleration sensor B is set as a detection sensor. In the second detection unit, acceleration sensor B is set as the reference sensor and acceleration sensor C is set as the detection sensor. In the third detection unit, acceleration sensor C is set as the reference sensor and acceleration sensor D is set as the detection sensor. In the fourth detection unit, acceleration sensor D is set as the reference sensor and acceleration sensor A is set as the detection sensor.

[0024] The comparator 44 compares two of the four detection values ​​input from the differential amplifier circuit 42, and calculates a difference between the two detection values. That is, the comparator 44 calculates a difference between the amplified detection value of the reference sensor and the amplified detection value of the detection sensor for each detection unit, and compares the difference between the detection values ​​in each detection unit with the threshold input from the threshold adjustment unit 43. This calculation process of the difference value and the comparison process of the difference value with the threshold are repeated at predetermined time intervals in the order of the first detection unit, the second detection unit, the third detection unit, and the fourth detection unit.

[0025] The comparator 44 determines that painting is being performed normally when the difference between the detection values ​​in each detection unit is smaller than the threshold input from the threshold adjustment unit 43. The comparator 44 determines that the coating gun 35 has collided with the workpiece W when the difference between the detection values ​​in any one of the four detection units is larger than the threshold input from the threshold adjustment unit 43. The threshold adjustment unit 43 is configured to include an input unit (not shown) and a memory (not shown) such as a semiconductor memory. The input unit can input a threshold based on the length of the arm 33, the weight of the coating gun 35, the driving speed of the reciprocator 22, the driving speed of the forward and backward drive member 32, etc. The input threshold can be stored in the memory of the threshold adjustment unit 43.

[0026] When powder coating is being performed normally without collision between the paint gun 35 and the workpiece W, acceleration occurs in the paint gun 35 when accelerating and decelerating immediately before and after a direction change as the paint gun 35 and arm 33 move up and down and back and forth. When changing direction in the up and down direction, the acceleration increases due to the bending deformation of the arm 33. When powder coating is being performed normally, the four paint guns 35 move synchronously as one unit, so the difference in detection values ​​between any two of the four paint guns 35 is smaller than the threshold value. Therefore, the comparator 44 determines that coating is being performed normally.

[0027] If the workpiece W is misaligned with respect to the hanger 12 or rotates horizontally, the coating gun 35 will collide with the workpiece W. Possible collision patterns include the coating gun 35 hitting the workpiece W from above or below, the coating gun 35 hitting the workpiece W from behind, and the workpiece W hitting the coating gun 35 from the left side (upstream side in the transport direction).

[0028] When any of the four paint guns 35 collides with the workpiece W from above or below, the acceleration sensor 41 (detection sensor) of the colliding paint gun 35 detects the acceleration caused by the impact at the time of the collision, and the difference between the detection value of this detection sensor and the detection value of the acceleration sensor 41 (reference sensor) of the non-colliding paint gun 35 is calculated by the comparator 44. When this difference value is greater than a threshold value, it is determined that the paint gun 35 has collided.

[0029] Also, when the acceleration caused by the impact at the time of collision is relatively small, the difference value between the detection value of the detection sensor and the reference sensor is smaller than the threshold value, so that it is not determined that a collision has occurred at the time of collision. In this case, the reciprocator 22 continues to be driven immediately after the collision, so that the arm 33 continues to be curved and deformed while the coating gun 35 remains hooked on the workpiece W, that is, does not rise or fall. Then, when the deformation of the arm 33 progresses to a certain extent, the coating gun 35 is released from the workpiece W by the elastic restoring force of the arm 33 and starts to rise or fall in one go. Since the acceleration at the time of starting this rise or fall is relatively large, the difference value calculated by the comparator 44 becomes larger than the threshold value. As a result, the comparator 44 determines that the coating gun 35 has collided with the workpiece W, and the occurrence of a collision is detected.

[0030] Similarly to the above, when the paint gun 35 collides with the workpiece W from behind, or when the workpiece W collides with the paint gun 35 from the left side, the acceleration sensor 41 (detection sensor) of the colliding paint gun 35 or the collided paint gun 35 detects the acceleration caused by the impact at the time of the collision, and the difference between the detection value of this detection sensor and the detection value of the acceleration sensor 41 (reference sensor) of the non-colliding paint gun 35 is calculated by the comparator 44. If this difference value is greater than the threshold value, the comparator 44 determines that the paint gun 35 has collided, and the occurrence of a collision is detected.

[0031] The control unit 45 is connected to the comparator 44. The control unit 45 is connected to the output unit 46, the conveyor driving unit 13, and the reciprocator driving unit 25. Examples of the output unit 46 include a monitor (not shown), a warning lamp (not shown), and a speaker (not shown). When the comparator 44 determines that the coating gun 35 has collided, the control unit 45 displays a message on the monitor informing of the collision, turns on or blinks the warning lamp, and generates a warning sound or message from the speaker. When a collision is determined, the control unit 45 stops the conveyance by the conveyor driving unit 13, stops the lifting and lowering drive by the reciprocator 22, and stops the discharge of the powder paint P from the coating gun 35. This minimizes the number of coating defects in the coating object W, and prevents the coating gun 35, the reciprocator 22, and the coating object W from being damaged due to collisions.

[0032] In the coating device of this embodiment 1, no expensive high-speed A / D converter, FPGA (field-programmable gate array), or microcomputer is required for performing FFT (fast Fourier transform) analysis to determine the presence or absence of a collision, and the determination can be made using only an operational amplifier. In addition, in electrostatic powder coating, the constant current function installed to prevent electrostatic repulsion operates relatively quickly, so a method of detecting a collision between the workpiece W and the coating gun 35 based on fluctuations in the corona discharge current cannot be adopted. However, the coating device for electrostatic powder coating of this embodiment 1 realizes detection of a collision between the workpiece W and the coating gun 35 by using the acceleration sensor 41.

[0033] The coating device includes four (plural) coating guns 35 that discharge powder coating material P toward the workpiece W, a drive unit 20, four acceleration sensors 41, and a determination unit 40. The drive unit 20 moves the four coating guns 35 in a synchronized state. The four acceleration sensors 41 are provided on the four coating guns 35 individually and individually detect impacts acting on the four coating guns 35. The determination unit 40 determines that the coating guns 35 and the workpiece W have collided when the difference in detection value between the acceleration sensors 41 between two coating guns 35 exceeds a threshold value.

[0034] According to the coating apparatus of this embodiment 1, when the coating gun 35 collides with the workpiece W, the difference between the detection value by the acceleration sensor 41 (detection sensor) of the coating gun 35 that has collided and the detection value by the acceleration sensor 41 (reference sensor) of the coating gun 35 that has not collided increases. When the difference between the two detection values ​​exceeds a threshold value, the judgment unit 40 judges that the coating gun 35 has collided with the workpiece W. Advanced processing such as FFT analysis is not required to judge whether or not a collision has occurred. According to the coating apparatus of this embodiment 1, the collision between the coating gun 35 and the workpiece W can be detected inexpensively and with high accuracy.

[0035] The coating device includes a conveyor 10 for transporting a workpiece W. The driving device 20 includes a reciprocator 22 for reciprocating four coating guns 35 in a vertical direction intersecting the transport direction of the conveyor 10 at a speed faster than the transport speed of the conveyor 10. The acceleration sensor 41 detects the acceleration in the vertical direction parallel to the movement direction of the reciprocator 22. With this configuration, the acceleration at the time of collision is larger when the coating gun 35 collides with the workpiece W parallel to the movement direction of the reciprocator 22 than when the coating gun 35 collides with the workpiece W parallel to the transport direction of the conveyor 10. Therefore, the collision between the coating gun 35 and the workpiece W can be reliably detected.

[0036] The reciprocator 22 has four (plural) elastically deformable arms 33 that protrude towards the workpiece W. Four paint guns 35 are individually attached to the front ends (protruding ends) of the four arms 33. With this configuration, if the impact at the time of collision is small and the collision is not detected, the arms 33 are elastically deformed as the reciprocator 22 continues to be driven after the collision, and then the paint guns 35 come off the workpiece W. When the paint gun 35 comes off the workpiece W, a large acceleration is generated in the paint gun 35 due to the elastic restoring force of the arms 33, so that the collision between the paint gun 35 and the workpiece W can be reliably detected.

[0037] The four paint guns 35 are supported by the reciprocator 22 with a gap between them parallel to the driving direction (up and down) of the reciprocator 22. The two paint guns 35 that are the object of judgment by the judgment unit 40 are arranged with a gap between them in the driving direction of the reciprocator 22. Since the driving direction by the reciprocator 22 is faster than the transport direction by the conveyor 10, only one of the two paint guns 35 that are the object of judgment will collide with the workpiece W. Therefore, a difference is always generated in the detection value of the acceleration sensor 41 between the two paint guns 35. Therefore, a collision can be reliably detected.

[0038] <Example 2> Next, a second embodiment of the present invention will be described with reference to Fig. 4. In the second embodiment, the determination unit 50 has a different configuration from that of the first embodiment. Since the other configurations are the same as those of the first embodiment, the same reference numerals are used for the same configurations, and the description of the structure, operation, and effect will be omitted.

[0039] The determination unit 50 of the second embodiment includes four acceleration sensors 41, four amplifier circuits 51, a threshold adjustment unit 52, and a microcomputer 53. As in the first embodiment, the four acceleration sensors 41 are attached to each paint gun 35. The configurations of the paint guns 35 and the acceleration sensors 41 are the same as in the first embodiment. The accelerations detected by the acceleration sensors 41 are input to the amplifier circuits 51. The detection signals amplified in the amplifier circuits 51 are input to the microcomputer 53.

[0040] The microcomputer 53 has a CPU (not shown) and a storage unit (not shown). The microcomputer 53 stores a program for calculating the difference between the detection values ​​of the two acceleration sensors 41, a program for comparing the calculated difference between the difference and a preset threshold, and a program for determining the presence or absence of a collision between the paint gun 35 and the workpiece W based on the comparison result between the difference and the threshold. In the microcomputer 53, "acceleration sensor A", "acceleration sensor B", "acceleration sensor C", and "acceleration sensor D" are set as in the comparator 44 of the first embodiment, and further, four types of detection units, 1st to 4th, are set as in the comparator 44 of the first embodiment. The microcomputer 53 compares two of the four detection values ​​input from the four amplifier circuits 51 and calculates the difference between the two detection values. That is, similar to the comparator 44 in the first embodiment, the microcomputer 53 calculates, for each detection unit, a difference between the amplified detection value of the reference sensor and the amplified detection value of the detection sensor, and compares the difference between the detection values ​​in each detection unit with the threshold input from the threshold adjustment unit 52. This calculation process of the difference value and the comparison process of the difference value with the threshold are repeated at predetermined time intervals in the order of the first detection unit, the second detection unit, the third detection unit, and the fourth detection unit.

[0041] Microcomputer 53 determines that powder coating is being performed normally when the difference between the detection values ​​in each detection unit is smaller than the threshold input from threshold adjustment section 52. Microcomputer 53 determines that paint gun 35 has collided with the workpiece when the difference between the detection values ​​in any one of the four detection units is larger than the threshold input from threshold adjustment section 52. Threshold adjustment section 52 can adjust the threshold based on the length of arm 33, the weight of paint gun 35, the drive speed of reciprocator 22, the drive speed of advance / retract drive member 32, etc.

[0042] When powder coating is being performed normally without collision between the paint guns 35 and the workpiece, the four paint guns 35 move synchronously as one unit, and the difference in detection value between any two of the four paint guns 35 is smaller than the threshold value. Therefore, the microcomputer 53 determines that powder coating is being performed normally.

[0043] When any of the four paint guns 35 collides with the workpiece from above or below, the acceleration sensor 41 (detection sensor) of the colliding paint gun 35 detects the acceleration caused by the impact at the time of the collision, and the difference between the detection value of this detection sensor and the detection value of the acceleration sensor 41 (reference sensor) of the non-colliding paint gun 35 is calculated by the microcomputer 53. When this difference value is greater than a threshold value, it is determined that the paint gun 35 has collided.

[0044] Also, if the acceleration caused by the impact at the time of collision is relatively small, it is not determined that a collision has occurred at the time of collision, but in this case as well, as in Example 1, the paint gun 35 gets caught on the workpiece as the arm 33 bends and deforms, and then the paint gun 35 comes off the workpiece due to the elastic restoring force of the arm 33 and starts to rise or fall in one go, so that the microcomputer 53 determines that the paint gun 35 has collided with the workpiece. If the paint gun 35 collides with the workpiece from behind, or if the workpiece collides with the paint gun 35 from the left side, the microcomputer 53 also determines that the paint gun 35 has collided, as in Example 1.

[0045] Similar to the first embodiment, the control unit 45 is connected to the microcomputer 53. The control unit 45 is connected to the output unit 46, the conveyor driving unit 13, and the reciprocator driving unit 25. When the microcomputer 53 determines that the paint gun 35 has collided, similar to the first embodiment, the control unit 45 outputs to the output unit 46, stops the conveyance by the conveyor driving unit 13, stops the lifting and lowering drive by the reciprocator 22, and stops the discharge of the powder paint from the paint gun 35.

[0046] In the second embodiment, the microcomputer 53 executes only simple processing, such as calculating the difference between two detection values ​​and comparing the difference with a threshold value, rather than performing FFT (fast Fourier transform) analysis using a sophisticated algorithm. Therefore, no expensive device is required to determine whether or not a collision has occurred.

[0047] <Other Examples> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention. In the first and second embodiments, two paint guns spaced apart in the vertical direction perpendicular to the conveyor's travel direction are used as the objects of judgment by the judgment unit. However, this is not limited to this, and the objects of judgment by the judgment unit may be two paint guns spaced apart in the conveyor's travel direction. In the first and second embodiments, four paint guns are provided on one reciprocator, but the number of paint guns provided on one reciprocator may be three or less, or five or more. In the first and second embodiments, the acceleration sensor is provided on the paint gun, but the acceleration sensor may be provided on the arm. In the first and second embodiments, the driving device includes a reciprocator, but the driving device may be a painting robot having a robot arm that moves in three dimensions, and a painting gun may be attached to the tip of the robot arm. In this case, multiple painting robots may be provided, and one painting gun may be attached to the robot arm of each painting robot, or multiple painting guns may be attached to the robot arm of one painting robot. In the above embodiments 1 and 2, the acceleration sensor detects acceleration in three dimensions, but the direction in which the acceleration sensor detects acceleration may be only a direction parallel to the movement direction of the reciprocator (up and down), or only a direction parallel to the conveying direction of the conveyor (left and right), or only any two of the three dimensions. In the above first and second embodiments, the case where the present invention is applied to a coating device for electrostatic powder coating has been described, but the present invention can also be applied to a non-electrostatic coating device or an electrostatic coating device that uses liquid paint. [Explanation of symbols]

[0048] P…Powder paint (paint) W…Object to be coated 10...Conveyor 20...Drive unit 22...Reciprocator 33…Arm 35…Paint gun 40…Judgment section 41...Accelerometer 50…Judgment section

Claims

1. A plurality of paint guns that spray paint toward the object to be painted; A drive device that moves the plurality of paint guns in a synchronized state; a plurality of acceleration sensors provided on the plurality of paint guns, each of which detects an impact acting on the plurality of paint guns; A coating device comprising: a judgment unit that judges that the coating gun and the workpiece have collided when a difference value of the detection value of the acceleration sensor between the two coating guns exceeds a threshold value.

2. A conveyor is provided for transporting the object to be coated, the driving device includes a reciprocator that reciprocates the plurality of paint guns in a direction intersecting a conveying direction of the conveyor at a speed faster than a conveying speed of the conveyor, 2. The coating device according to claim 1, wherein the acceleration sensor detects acceleration in a direction parallel to a direction of movement of the reciprocator.

3. the reciprocator has a plurality of elastically deformable arms protruding toward the workpiece, 3. The coating device according to claim 2, wherein said coating guns are individually attached to the projecting ends of said arms.

4. The plurality of paint guns are supported by the reciprocator at intervals in a direction parallel to a drive direction of the reciprocator, 4. The coating apparatus according to claim 2, wherein the two coating guns that are the objects of the determination by the determination unit are disposed at an interval in the driving direction of the reciprocator.

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