ROBOT FOR COATING VEHICLE BODY

A coating device has a coating head that dispenses coating material toward a vehicle body. The coating device also includes a supply device that has a circulation path for circulating the coating material between a reservoir storing the coating material and the coating head, and is capable of controlling the pressure of the coating material flowing through the circulation path. The coating device includes an arm having the coating head and the supply device, wherein the coating robot performs coating of the vehicle body while moving the coating head wherein the coating head moves at a first speed toward a coating start position to start coating the vehicle and moves at a second speed different from the first speed when it reaches a specific position in a movement path to the coating start position.

TECHNICAL FIELD

This invention relates to a robot for coating a vehicle body which is equipped with a coating head having multiple nozzles that spray out a coating material.

BACKGROUND ART

There is a widespread technology for coating vehicle bodies using a coating robot equipped with coating heads having multiple nozzles to dispense a coating material. Such a coating robot has a multi-axis arm having, for example, multiple arm members and a movable shaft connecting each arm member to one another, and of the multiple arm members, a coating head is provided in the arm member that is the tip, and a supply device for supplying a coating material to the coating head is provided (see, for example, Patent Document 1). The coating material supply device includes, for example, a tank for storing coating material, a supply path for supplying coating material to the coating head, and a return flow path for refluxing coating material not used by the coating head to the tank, so that the coating material is circulated between the tank and the coating head. The coating material supply device also includes a supply pump that pumps coating material into the supply path and a retraction pump that draws coating material into the return flow path, which is controlled based on the detection results of the detection means provided in the supply path and the return flow path. As a result, during operation of the coating robot, the pressure of the coating material flowing through the supply path and return flow path can be kept at the proper pressure.

PRIOR ART DOCUMENTS

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

The coating head is moved forward and backward, for example, multiple times in the main scanning direction by operation of the multi-axis arm of the coating robot, and is also moved a predetermined amount in the sub-scanning direction each time it is moved in the main scanning direction. In such a multi-axis arm operation, the pressure of the coating material flowing through the coating material supply device will easily fluctuate due to acceleration at the start of operation, deceleration at the stopping of movement, and vibration of the multi-axis arm itself. Such coating material pressure fluctuations destabilize the coating material supply to the coating head and cause variations in the amount of coating material dispensed from the multiple nozzles provided on the coating head. In addition, the vibration of the multi-axis arm itself disrupts the landing position of the coating material ejected from the multiple nozzles provided on the coating head. Due to these causes, the coating quality of the vehicle body by coating heads deteriorates.

This invention has been invented to solve the problems described above and is intended to provide a vehicle body coating robot capable of inhibiting deterioration of coating quality due to the coating head by inhibiting pressure fluctuations and vibrations of the multi-axis arm during operation of the multi-axis arm of the coating robot.

Means for Solving the Problem

To solve the problems described above, the robot for coating the vehicle body of this invention has a coating head that dispenses coating material onto the vehicle body; a supply device that has a circulation path for circulating the coating material between a reservoir storing the coating material and the coating head, and that is capable of controlling the pressure of the coating material flowing through the circulation path; and an arm having a coating head and a supply device; and it is a robot for coating a vehicle body that coats the vehicle body while moving the coating head in a main scanning direction by operation of the arm, wherein: it has a control means for controlling operation of the arm; and the coating head moves at a first speed toward the coating start position where the coating of the vehicle body is started by the movement of the arm by the control means, and when it reaches a specific position provided in the movement path to the coating start position, it moves at a second speed different from the first speed.

In addition, the second speed is set to be less than the first speed, or the first speed is set to be less than the second speed.

In addition, when the coating head reaches the coating start position, coating of the vehicle body is started while maintaining the second speed.

In addition, the coating head moves forward and backward multiple times in the main scanning direction and moves a predetermined amount in a sub-scanning direction orthogonal to the main scanning direction upon switching the forward and backward movement in the main scanning direction; and the coating start position is provided at each of the forward path and backward path in a forward and backward movement of the main scanning direction.

In addition, the coating head is moved at a third speed that is slower than the second speed when moving a predetermined amount in the sub-scanning direction.

In addition, the robot for coating a vehicle body has a coating head that dispenses coating material onto the vehicle body; a supply device that has a circulation path for circulating the coating material between a reservoir storing the coating material and the coating head, and that is capable of controlling the pressure of the coating material flowing through the circulation path; and an arm having a coating head and a supply device; and it is a robot for coating a vehicle body that coats the vehicle body while moving the coating head in a main scanning direction by operation of the arm, wherein: it has a control means for controlling operation of the arm; the coating head is moved to a coating start position to start coating of the vehicle body by controlling the arm by the control means, stopped temporarily and then resumes movement from the coating start position to the main scanning direction after a predetermined time has elapsed since stopping at the coating start position to perform coating of the vehicle body, and the movement speed of the coating head when coating the vehicle body is set to a movement speed different from the movement speed of the coating head when moving to the coating start position.

In addition, the coating head moves forward and backward multiple times in the main scanning direction and moves a predetermined amount in a sub-scanning direction orthogonal to the main scanning direction upon switching the forward and backward movement in the main scanning direction; the coating start position is provided at each of the forward path and backward path in a forward and backward movement in the main scanning direction; and the coating head is temporarily stopped at the coating start position provided at each of the forward path and backward path.

In addition, the coating head is held at an initial position when not coating the vehicle body; and the control means controls operation of the arm to move the coating head from the initial position to the coating start position upon initiation of coating to the vehicle body.

In addition, the circulation path includes a supply path for supplying the coating material stored in the reservoir to the coating head and a return flow path for refluxing the coating material not used by the coating head to the reservoir; and the coating device has a dispensing means for feeding the coating material stored in the reservoir to the supply path; a retracting means for drawing the coating material from the coating head into the return flow path; a first detection means for detecting the pressure of the coating material fed to the supply path; a second detection means for detecting the pressure of the coating material drawn into the return flow path; a pressure control means for controlling the amount of coating material dispensed by the dispensing means based on a detection result by the first detection means and for controlling a drawing amount of the coating material by the retracting means based on a detection result by the second detection means.

Effect of the Invention

According to this invention, it is possible to provide a robot for coating a car body by suppressing pressure fluctuation and vibration of the multi-axis arm that occurs during the operation of the multi-axis arm, thereby inhibiting deterioration of coating quality by the coating head.

MODES FOR CARRYING OUT THE INVENTION

A robot10for coating a vehicle body which implements this invention will be described below on the basis of the drawings. The robot10for coating a vehicle body is hereinafter referred to as a coating robot10. The coating robot10of this embodiment is arranged to the side of a coating line in an automobile manufacturing plant and is used for coating vehicle bodies FR conveyed along the coating line.

Moreover, in this embodiment, the object to be coated by the coating robot10(hereinafter referred to as the “object of coating”) is an automobile body FR as an example, but the object of coating may also be an automobile part other than a vehicle body (examples include, but are not limited to, doors, hoods, various panels, etc.), or various parts other than automobile parts (for example, airplane or railway exterior parts), and thus is not limited to a vehicle body of an automobile and may be any object that requires coating.

Coating here is performed for the purpose of forming a coating film on the surface of the object of coating to provide protection of that surface and improved appearance. Therefore, coating includes not only the coating of an object of coating using coating material of a specific color or coating material having a specific function, but also the coating of an object of coating using coating materials of multiple colors in sequence. Furthermore, coating includes coating of patterns, illustrations, images, etc.

As shown inFIGS.1(a) and1(b), the coating robot10has, by way of example, a robot arm15and a coating head unit17. The robot arm15is composed of a multi-axis arm having a base21and multiple (two inFIG.1) arm members22,23. The base21has a fixed portion24and a rotating portion25rotatable relative to the fixed portion24. Here, base21corresponds to the base described in the Claims. Fixed portion24includes a motor M1 (seeFIG.3) inside. The rotating portion25rotates as a rotation center in a direction perpendicular to the floor surface of the coating line (hereinafter referred to as the vertical direction) due to the drive of the motor M1.

Hereinafter, among the multiple arm members22,23, the arm member22coupled to the rotating portion25is referred to as the first rotary arm22, and the arm member23coupled to the first rotary arm22is referred to as the second rotary arm23.

The first rotary arm22is coupled to the movable shaft portion26provided in the rotating portion25at one end in the direction of extension of the first rotary arm22. The movable shaft26provided in the rotating section25is provided with a motor M2 (seeFIG.3) to cause the coupled first rotary arm22to rotate on a plane orthogonal to the floor surface of the coating line (e.g., a yz plane when the robot arm15is in the state ofFIG.1(b)).

In the direction of extension of the first rotary arm22, the second rotary arm23is coupled via the movable shaft27to the other end, which is opposite to the one end coupled to the movable shaft26of the rotating portion25. The movable shaft27is provided with a motor M3 (seeFIG.3) as described below to cause the coupled second rotary arm23to rotate on a plane orthogonal to the floor surface of the coating line (e.g., a yz plane when the robot arm15is in the state ofFIG.1(b)). Moreover, although the illustration is omitted, the center axis of the movable shaft portion26of the rotating portion25and the center axis of the movable shaft portion27provided in the first rotary arm22are parallel. Moreover, although details will be described below, the second rotary arm23is provided with a coating material circulation device51as described below.

The other end of the second rotary arm23in the direction of extension is provided with a wrist portion28. The wrist portion28holds the coating head unit17. The wrist portion28has multiple motors M4, M5, M6 (3 motors here) each with a different axis direction of the drive shaft, and driving any of these motors causes the held coating head unit17to rotate using any one of the multiple shafts that the wrist portion28has as a rotation center. It should be noted that the number of shafts should be two or more.

The coating head unit17includes a coating head56as described below, a head control unit (seeFIG.3) for controlling operation of said coating head56, and the like.

As described above, a coating material circulation device51is provided inside the second rotary arm23. As shown inFIG.2, the coating material circulation device51has, for example, a supply path57that supplies coating material stored in the coating material tank55to the coating head56, and a return flow path58(reflux path) that returns coating material not used in the coating head56to the coating material tank55from the coating head56, and a bypass path59that flows from the supply path57to the return flow path58without supplying coating material to the coating head56. Here, the coating material tank55corresponds to the reservoir as described in the Claims. In addition, the coating material circulation device51also mounts a coating material tank55, gear pump62on the floor of coating material room, and houses parts such as, for example, removal filter63, degassing module64, switching valve parts67,68,70,78, proportional valves71,77, and pressure gauges69,72,76,79, etc. inside the second rotary arm23. Here, the coating material circulation device51corresponds to the supply device as described in the Claims. Moreover, the gear pump62may employ a configuration that is housed, for example, within the second rotary arm23. In addition, a configuration may be employed in which at least one part of the removal filter63, degassing module64, switching valve, proportional valve, pressure gauge, and the like is mounted on the floor.

The coating material circulation device51circulates coating material between the coating material tank55and the coating head56by supplying coating material stored in the coating material tank55to the coating head56when coating the vehicle body FR and refluxing coating material not used in the coating head56from the coating head56to the coating material tank55. In addition, when the coating material circulation device51is not coating the vehicle body FR, the coating material stored in the coating material tank55flows through the supply path57, bypass path59, and return flow path58, in that order, and returns to the coating material tank55.

By the way, coating materials used for coating the vehicle body FR are water-based coating materials and solvent-based coating materials using pigments, for example. Thus, by circulating the coating material by the coating material circulation device51, separating the pigments contained in the coating material and agglomerating the pigments is prevented.

When describing the configuration of the supply path57of the coating material circulation device51, the coating material tank55side is the upstream side and the coating head56side is the downstream side in the coating material supply direction. Moreover, when describing the configuration of the return flow path58of the coating material circulation device51, the coating head56side is the upstream side and the coating material tank55side is the downstream side.

The coating material tank55stores the coating material used for coating the vehicle body FR using the coating head56. The coating material tank55is arranged outside the coating robot10(for example, on the floor of the coating room). Moreover, the coating material tank55is supplied with coating material from outside as necessary in the process of coating the vehicle body FR using the coating head56. In addition, if coating material is refluxed from the return flow path58to the coating material tank55, air bubbles flowing with the coating material float on a liquid surface within the coating material tank55, which may have the function of removing the air bubbles.

The coating head56has a nozzle forming surface56awith multiple nozzles61arranged in a two-dimensional array, and the coating material supplied via the supply path57is discharged from each of the multiple nozzles61to form a coating film on the surface of the vehicle body FR. Moreover, the detailed configuration of the coating head56is omitted.

Supply path57is a path that supplies coating material stored in the coating material tank55to the coating head56. The supply path57has flow paths57a,57b, ...,57h,57i, as described below. In addition, in the middle of the supply path57, from the upstream side of the supply path57, the gear pump62, the removal filter63, and the degassing module64are arranged in this order.

The gear pump62draws in the coating material stored in the coating material tank55and feeds the drawn-in coating material toward the coating head56. Therefore, when the gear pump62is driven, the pressure on the upstream side of the gear pump62, i.e. inside the flow paths57aand57bbetween the coating material tank55and the gear pump62, becomes negative, and the coating material stored in the coating material tank55is drawn into the flow paths57aand57b. It is then fed from the gear pump62to the flow path57cconnected to the downstream side of the gear pump62. Here, the gear pump62corresponds to the dispensing means as described in the Claims.

The flow path57aand flow path57bthat make up the supply path57are connected by a three-way valve part66. The three-way valve part66can be switched to either a state in which the flow path57aand the flow path57bare in communication or a state in which the flow path57bis in communication with a drain path connected to the drain tank83. The three-way valve part66is held in communication with the flow path57aand the flow path57b, for example, when coating the vehicle body FR. In addition, the three-way valve part66is in a state of communicating the flow path57band the drain tank83(in particular, the flow path not shown in the drawings that is connected to the drain tank83) when cleaning the supply path57.

In the supply path57, the gear pump62is connected with the flow path57cat the output side. A switching valve67is provided at the downstream side end of the flow path57c. The switching valve part67has four valve parts67a,67b,67c, and67d. For example, the valve part67ais connected to the flow path57c, and the valve part67bis connected to the flow path57dthat is directed to the removal filter63. In addition, the valve part67cis connected to the cleaning tank82(in detail, the flow path not shown in the drawings that is connected to the cleaning tank82). Furthermore, the valve part67dis connected to the drain tank83(in detail, the flow path not shown in the drawings that is connected to the drain tank83). Of these valves, the valve part67aand the valve part67bare normally held in an open state. On the other hand, valve parts67c,67dare normally held in a closed state and are switched from a closed state to an open state upon cleaning of the coating material circulation device51.

A removal filter63is provided downstream of the flow path57dconnected to the valve part67bof the switching valve67. The removal filter63removes foreign matter such as coarse particles and pigment agglomerates contained in the coating material, as well as bubbles that exceed a predetermined size among the bubbles contained in the coating material. The removal filter63is for example a mesh-like body such as a metal net or resin net, or a porous body, or a metal plate in which fine through-holes have been formed. Examples of a mesh-like body include metal mesh filters, metal fibers, e.g., fine strands of metal known as SUS made into the form of felt, metal sintered filters which have been compressed and sintered, electroformed metal filters, electron beam processed metal filters, laser beam processed metal filters, and the like.

A switching valve68is provided downstream of the flow path57econnected to the output side of the removal filter63. Similarly to the switching valve67, the switching valve part68has four valve parts68a,68b,68c, and68d. For example, the valve part68ais connected to the flow path57e, and the valve part68bis connected to the flow path57fthat is directed to the degassing module64. In addition, the valve part68cis connected to the cleaning tank82(in detail, the flow path not shown in the drawings that is connected to the cleaning tank82). In addition, the valve part68dis connected to the drain tank83(in detail, the flow path not shown in the drawings that is connected to the drain tank83). Of these valves, the valve part68aand the valve part68bare normally held in an open position. On the other hand, the valve parts68c,68dare normally held in a closed state and are switched from a closed state to an open state upon cleaning of the coating material circulation device51.

A degassing module64is provided downstream of the flow path57fconnected to the valve part68bof the switching valve. The degassing module64removes (degasses) dissolved gas and air bubbles present in the coating material. Examples of the degassing module64include a hollow fiber membrane bundle made by bundling multiple hollow fiber membranes.

A pressure gauge69is provided in the flow path57gconnected to the output side of the degassing module64. The pressure gauge69measures the pressure of the coating material dispensed from the degassing module64. The measurement result by the pressure gauge69is output to the coating material supply control unit103(seeFIG.3). The gear pump62is driven by the coating material supply control unit103so that the pressure value detected by the pressure gauge69is constant. Moreover, the pressure gauge69corresponds to the first detection means as described in the Claims. In addition, in the supply path57, a pressure gauge other than the pressure gauge69may be provided.

At the downstream side end of the flow path57gdescribed above, a switching valve70is provided. Similarly to the switching valve67and the switching valve68, the switching valve70has four valve parts70a,70b,70c, and70d. For example, the valve part70ais connected to the flow path57g, and the valve part70bis connected to the flow path57h. In addition, the valve part70cis connected to the cleaning tank82(in detail, the flow path not shown in the drawings that is connected to the cleaning tank82). In addition, the valve part70dis connected to the drain tank83(in detail, the flow path not shown in the drawings that is connected to the drain tank83). Of these valves, the valve part70aand the valve part70bare normally held in the open state. On the other hand, the valve parts70c,70dare normally held in a closed state and are switched from a closed state to an open state upon cleaning of the coating material circulation device51.

A proportional valve71is connected to the downstream side end of the flow path57hconnected to the valve portion70bof the switching valve. The proportional valve71is opened and closed by the coating material supply control unit103so that the pressure value of the coating material flowing downstream of the proportional valve71is constant.

A flow path57iis provided downstream of the proportional valve71. The flow path57iis provided with a pressure gauge72and a one-way valve73. The pressure gauge72measures the pressure of coating material flowing from the proportional valve71toward the coating head56. The one-way valve73flows coating material in one direction (in this case, from proportional valve71towards the coating head56) and prevents it from flowing in the opposite direction. Moreover, the upstream side end of the bypass path59is connected to the flow path57hbetween the pressure gauge72and the one-way valve73.

The return flow path58is a flow path that returns coating material not used by the coating head56when coating to the vehicle body FR, or that is circulated through the bypass flow path59to the coating material tank55. The return flow path58has flow paths58a,58b,58c,58d, and58e.

A coating head56is connected to the flow path58aat the upstream side end. The flow path58ais provided with a one-way valve75and a pressure gauge76. The one-way valve75flows coating material in one direction (in this case, from coating head56toward pressure gauge76) and prevents it from flowing in the opposite direction. It should be noted that the downstream side end of the bypass flow path59is connected to the flow path58abetween the one-way valve75and the pressure gauge76. The pressure gauge76measures the pressure of the coating material flowing upstream of the proportional valve77(i.e., from the coating head56toward the proportional valve77).

A proportional valve77is provided downstream of the flow path58a. The proportional valve77is controlled by the coating material supply control unit103to open and close and to maintain a constant pressure value of the coating material flowing from the coating head56toward the proportional valve77.

A switching valve78is provided downstream of the flow path58bconnected to the output side of the proportional valve77. Similarly to the switching valves67,68,70provided in the supply path57, the switching valve78has four valve parts78a,78b,78c, and78d. For example, the valve part78ais connected to the flow path58b, and the valve part78bis connected to the flow path58cdirected to gear pump80. In addition, the valve part78cis connected to the cleaning tank82(in detail, the flow path not shown in the drawings that is connected to the cleaning tank82). In addition, the valve part78dis connected to the drain tank83(in detail, the flow path not shown in the drawings that is connected to the drain tank83). Of these valves, valve78aand valve78bare normally held in the open position. On the other hand, valves78c,78dare normally held in a closed state and are switched from a closed state to an open state upon cleaning of the coating material circulation device51.

The flow path58cis provided with a pressure gauge79. The pressure gauge79measures the pressure of the coating material flowing into the flow path58c. The measurement result by the pressure gauge79is output to the coating material supply control unit103. Moreover, the pressure gauge79corresponds to a second detection means as described in the Claims.

A gear pump80is provided at the downstream side end of the flow path58c. The gear pump80draws coating material into the flow path58cand pumps the drawn coating material toward the coating material tank55. Therefore, by driving the gear pump80, the pressure inside the upstream side of the gear pump80, i.e., the flow path58c, becomes negative, and the coating material is drawn into the flow path58c. The coating material is then pumped from the gear pump80to a flow path58dconnected to the downstream side of the gear pump80. At this time, the gear pump80is driven and controlled by the coating material supply control unit103so that the pressure value detected by the pressure gauge79is a constant value. Here, the gear pump61corresponds to the first pump as described in the Claims.

A three-way valve81is connected to the downstream side of the flow path58dconnected to the output side of the gear pump80. The three-way valve81switches between a state in which the flow path58dis connected to the flow path58econnected to the coating material tank55and a state in which the flow path58dis connected to the drain tank83. The three-way valve81is kept in the state of connecting the flow path58dand flow path58eduring coating of the vehicle body FR by the coating head56or during circulation of the coating material. The three-way valve81switches from connecting the flow path58dand the flow path58eto connecting the flow path58dand the drain tank83during cleaning. As a result, the cleaning liquid and air flowing through the flow path58dare discharged into the drain tank83via the three-way valve81.

The bypass path59is connected to the flow path57iand the flow path58ato flow a portion of the coating material flowing through the supply path57to the return flow path58without flowing to the coating head56when coating material is not coated by the coating head56. A control valve84is provided in the bypass path59. The control valve84is held closed when coating the vehicle body FR by the coating head56and is switched to an open state when coating the vehicle body FR by the coating head56is not performed.

Next, a configuration to control the coating robot10described above (hereinafter referred to as a control system) will be described.FIG.3is a diagram illustrating a configuration of a control system. As shown inFIG.3, the control system100has a main control unit101, an arm control unit102, a coating material supply control unit103, and a head control unit104. Although the illustration by drawing is omitted, the main control unit101, the arm control unit102, the coating material supply control unit103, and the head control unit104are composed of a Central Processing Unit (CPU), a memory part (Read Only Memory (ROM), Random Access Memory (RAM), non-volatile memory, and the like), and other elements.

The main control unit101sends predetermined control signals to each of the arm control unit102, coating material supply control unit103, and head control unit104so that the robot arm15, coating material circulation unit51, and coating head56cooperate to perform coating on the object to be coated.

The arm control unit102provides drive control for each of the motors M1, M2, M3, M4, M5, and M6 provided in the robot arm15based on various data stored in the arm memory106it owns. Here, various data stored in the arm memory106are required when coating the vehicle body FR by the coating robot10, and includes, for example, data on the external shape of the vehicle body FR to be coated, trajectory data indicating the movement trajectory of the coating head unit17when coating the vehicle body FR, posture data indicating the posture of the robot arm15and the coating head unit17, and the like. Here, the arm control unit102corresponds to the control means as described in the Claims.

Here, the coating of the vehicle body FR with the coating robot10shown in this embodiment is carried out while maintaining the second rotary arm23in a horizontal state, i.e., in a state in which the extension direction of the second rotary arm23is included in the horizontal plane. Accordingly, the posture data include, for example, the posture of the first rotary arm22(the amount of rotation of the motor M1 and the motor M2) when the second rotary arm23is maintained in a horizontal state, as well as the posture of the second rotary arm23(the amount of rotation of the motor M3) relative to the first rotary arm22.

It should be noted that various data described above are stored in the arm memory106corresponding to each of the multiple vehicle body FRs with different external shapes when coating multiple vehicle body FRs with different external shapes by the coating robot10.

The coating material supply control unit103controls the drive of the gear pumps62,80and the opening and closing of the proportional valves71,77based on the measurement results of the pressure gauges69,72,76, and79provided in the coating material circulation device51described above to circulate the coating material stored in the coating material tank55of the coating material circulation device51between the coating material tank55and the coating head56. Here, the coating material supply control unit103corresponds to the pressure control means as described in the Claims.

The head control unit104operates the piezoelectric substrate109based on the position information of the coating head56detected by the position sensor107. Here, the head control unit104is not only capable of controlling the operation of the piezoelectric substrate109, but also capable of controlling the operating frequency relative to the piezoelectric substrate109, controlling the voltage applied to the piezoelectric substrate109, and controlling the amount of droplets of coating material ejected from each of the multiple nozzles61provided on the nozzle forming surface56aof the coating head56.

The position sensor107detects the position of the coating head56moving under the control of the arm control unit102and outputs its detection signal to the main control unit101. The inclination sensor108used can be, for example, a gyro sensor. The inclination sensor108detects the inclination of the robot arm15and the coating head56and outputs the detection signal to the main control unit101.

Next, an example of control of the vehicle body FR in coating using the coating robot10will be described. Moreover,FIG.4(a)shows an example of a moving trajectory of coating head56on an xy plane when coating onto a vehicle body FR, andFIG.4(b)shows an example of a moving trajectory of coating head56on an xz plane when coating onto a vehicle body FR. In addition,FIG.5is also a diagram illustrating an example of a change in the movement speed of the coating head56when coating to the vehicle body FR.

As shown inFIGS.4(a) and4(b), when the coating robot10is not coating the vehicle body FR, the coating head56is held, for example, in a standby position (position P1 inFIG.4(a). When coating by the coating robot10begins, the arm control unit102drives the motors M1, M2, M3, M4, M5, and M6. This causes the first rotary arm22, the second rotary arm23, and the wrist portion28of the robot arm15to operate to move the coating head56from position P1 to position P2. Here, assuming the movement speed of the coating head56from position P1 to position P2 as V1, the movement speed V1 is, by way of example, V1 = 300 mm/s.

Thereafter, after the coating head56reaches position P2, the arm control unit102slows down the movement speed of the coating head56moving under the drive of motors M1, M2, M3, M4, M5, and M6 to move the coating head56from position P2 to position P3. Moreover, as shown inFIGS.4(a) and4(b), position P3 is in the lower position relative to position P2, and the drive of the robot arm15causes the coating head56to move on the yz plane. At this time, the coating head56can be moved in the y-direction inFIG.4(a)and then in the -z-direction inFIG.4(b)(or vice versa), or simultaneously in the y-direction inFIG.4(a)and in the -z direction inFIG.4(b). Here, the movement speed V2 of the coating head56moving from position P2 to position P3 is set in the range of, for example, 30 mm/s to 100 mm/s.

When the coating head56reaches position P3, the arm control unit102moves the coating head56from position P3 to position P4 without changing the movement speed of the coating head56moving under the drive of motors M1, M2, M3, M4, M5, and M6.

For example, in the coating of the vehicle body FR by the coating head56, forward and backward movement between position P4 and position P5 in the -x direction or in the x direction is performed, and when moving either from position P4 to position P5 or from position P5 to position P4, coating is performed using multiple nozzles61provided on the nozzle forming surface56a(hereinafter coating using all of the multiple nozzles61provided on the nozzle forming surface56ais referred to as coating for one line), and when the coating for one line is completed, the coating head56is moved one line in the -y direction. That is, the movement of the coating head56from position P4 to position P5 corresponds to the movement of the forward path in the forward and backward movement in the main scanning direction. Also, the movement of the coating head56from position P5 to position P4 corresponds to the movement of the backward path in the forward and backward movement in the main scanning direction.

The movement speed when the coating head56moves from position P4 to position P5 and the movement speed when moving from position P5 to position P4 is the movement speed V2. The movement speed of the coating head56when moving the coating head56one line in the -y direction may also be the same speed as the movement speed V2 from position P2 to position P3, or may be less than these movement speeds V2.

When the coating head56is moved between positions P4 and P5, i.e., when the coating head56moves along a forward path in the forward and backward movement in the main scanning direction, the arm control unit102drives M1, M2, M3, M4, M5, and M6 with reference to the data of the contour shape of the vehicle body FR stored in the arm memory106. Thus, the coating head56moves along the contour shape of the vehicle body FR with a predetermined spacing relative to the vehicle body FR.

As the coating head56moves from position P4 to position P5, the coating head passes through position P4 to initiate processing prior to coating initiation, and when the coating head56reaches one end of the vehicle body FR (position P6), coating material is ejected from the multiple nozzles61provided at the nozzle forming surface56aof the coating head56. When the coating head56is moved to reach the other end of the FR of the vehicle body in the main scanning direction (position P7), the discharge of coating material from the multiple nozzles61provided on the nozzle forming surface56aof the coating head56is stopped, and the treatment associated with the end of coating is started, and when the position P5 is reached, the operation of the coating head56completely ends.

As the coating head56moves to position P5, one line of coating by the coating head56ends. The arm control unit102then continues to drive the motors M1, M2, M3, M4, M5, and M6 to move the coating head56one line in the -y direction ofFIG.4.

The arm control unit102then drives the motors M1, M2, M3, M4, M5, and M6 and changes the posture of the robot arm15to move the coating head56from position P5 toward position P4. Moreover, the movement speed of the coating head56is V2.

When the coating head56is moved from position P5 toward position P4, a treatment prior to coating initiation is initiated, and when the coating head56reaches the other end of the vehicle body FR (position P7), coating material is dispensed from the multiple nozzles61provided on the nozzle forming surface56aof the coating head56. Then, when one end of the FR of the vehicle body (position P6) in the main scanning direction is reached, the discharge of coating material from the multiple nozzles61provided on the nozzle forming surface56aof the coating head56is stopped, and processing associated with coating completion is started, and when the position P4 is reached, the operation of the coating head56completely ends.

That is, when the coating head56moves along the forward path in the forward and backward movement in the main scanning direction, position P4 becomes the coating start position and position P5 becomes the coating end position. At this time, the discharge of the coating material by the multiple nozzles61of the coating head56is performed from position P6 to position P7. In addition, when the coating head56moves along the backward path in the forward and backward movement in the main scanning direction, position P5 becomes the coating start position and position P4 becomes the coating end position. At this time, the discharge of the coating material by the multiple nozzles61of the coating head56is performed from position P7 to position P6.

In the coating of the vehicle body FR, the coating head56is moved from position P4 to position P5 (or vice versa) and then moved one line in the -y direction multiple times. Then, when the entire vehicle body FR is coated and moved to position P5, the arm control unit102drives the motors M1, M2, M3, M4, M5, and M6 to move the coating head56from position P5 to position P1.

At the time of movement of the coating head56described above, based on the detection results of the pressure gauge69provided in the supply path57of the coating material circulation device51and the pressure gauge79provided in the return flow path58, the pressure of the coating material flowing through the supply path57and the return flow path58is controlled. In addition, the opening and closing control of the proportional valve71by the pressure gauge72and the opening and closing control of the proportional valve77by the pressure gauge76are performed.

In performing the coating using the coating robot10described above, the pressure supplied to the coating head56and the pressure dispensed from the coating head56are taken into account below.

FIG.6(a)shows the displacement of the pressure on the input side of the coating head56when the vehicle body FR is coated after deceleration of the coating head56at position P2;FIG.6(b)shows the displacement of the pressure on the output side of the coating head56when the vehicle body FR is coated after deceleration of the coating head56at position P2. In addition,FIG.7(a)shows the displacement of the pressure on the input side of the coating head56when the vehicle body FR is coated after deceleration of the coating head56at position P4;FIG.7(b)shows the displacement of the pressure on the output side of the coating head56when the vehicle body FR is coated after deceleration of the coating head56at position P4.

Here, in the vehicle body FR, the pressure of the coating material flowing toward the coating head56is reduced to a target value of 0.1 bar, and the pressure of the coating material pumped out of the coating head56is reduced to a target value of -0.1 bar.

As shown inFIGS.6(a) and6(b), when the vehicle body FR is coated after the coating head56has decelerated at position P2, the coating material pressure at the input side of the coating head56is changing within a range of 0.09 bar to 0.11 bar. In addition, the pressure of the coating material at the output side of the coating head56is changing within a range of -0.1050 bar to -0.0915 bar. It should be noted that these pressure changes are believed to be due to, for example, changes in the posture of the first and/or second rotary arms22,23of the robot arm15, inertia of the coating material due to deceleration of the coating head56, and the like.

On the other hand, as shown inFIGS.7(a) and7(b), when the vehicle body FR is coated after the coating head56has decelerated at position P4, the coating material pressure at the input side of the coating head56is changing within a range of 0.0875 bar to 0.1125 bar. In addition, the pressure of the coating material at the output side of the coating head56is changing within a range of -0.10875 bar to -0.0875 bar. At this time, for example, three seconds after the start of coating, the result was that a large change in pressure was observed. In addition, in this case, the pressure changes are large. This is believed to be due to the start of coating, with the inertia, etc. of coating material not converging when the coating head56decelerates rapidly at position P4.

In other words, it was found that in a case when the coating head56decelerates at position P2, the change in coating material pressure at the input side and output side of the coating head56during coating is suppressed compared to the case when the coating head56decelerates at position P4. That is, as shown inFIG.5, in front of the position P4 where the coating preparation by the coating head56starts (position P2), the movement speed of the coating head56is decelerated and the movement speed of the coating head56is regarded as the movement speed V2 when coating to the vehicle body FR. For example, when the moving coating head56decelerates, the pressure of the coating material supplied to the coating head56and the pressure of the coating material dispensed from the coating head56will change due to inertia of the coating material and vibration of the robot arm15, but such speed control of the coating head56can converge the change in the pressure of coating material associated with the deceleration of the coating head56within a period of time until coating of the vehicle body FR begins. As a result, stable coating of the vehicle body FR can be performed without deteriorating the coating performance of the vehicle body FR by the coating head56.

Moreover, although in this embodiment, the coating head56is decelerated at position P2, the position that decelerates the movement speed of the coating head56need not be limited to position P2, and for example, it is fine to be the position at which the pressure change associated with deceleration of the movement speed of the coating head56is converged before the coating by the coated head56starts.

In addition, in this embodiment, the coating head56is decelerated at position P2, and the vehicle body FR is coated by the coating head56while maintaining a decelerated movement speed. For example, the movement speed of the coated head56during the coating of the vehicle body FR is determined by the coating performance of the coating head56to a fixed speed. Therefore, it is also possible to speed up the movement speed of the coating head56to become the movement speed of the coating head56when the coating head56passes through position P2, for example, when position P3 or position P4 is reached, after deceleration to a speed slower than the movement speed of the coating head56when coating the vehicle body FR. According to this embodiment, the pressure variation of the coating material when slowed down is large, but the pressure change of the coating material before and after acceleration and the vibration of the robot arm15can be suppressed as much as possible, and the coating performance can be improved.

It is also possible to speed up the coating head56to a movement speed of the coating head56when coating the vehicle body FR at the position P2 or position P3 rather than slowing down the coating head56at position P2 (or position P3). In this case, the movement speed of the coating head56can be increased incrementally, so that the pressure change of the coating material during each acceleration and vibration of the robot arm15can be suppressed.

In this embodiment, the coating head56is decelerating at position P2, but can also be stopped for a predetermined time, for example at position P4. Moreover, the predetermined time is the time until the pressure change associated with the stop of the coating head56converges, for example, it can be set to 5 seconds. Moreover, the predetermined time may be set according to the movement speed as the coating head56moves from position P1 to position P4, or may be set based on measurement results of at least one of the pressure gauges69,72,76,79of the coating material circulation device51described above.

At this time, as shown inFIG.8, when moving the coating head56along the forward path in the forward and backward movement in the main scanning direction, the coating head56is accelerated to be the desired movement speed (e.g., movement speed V2) at position P6 when moving from position P4 shown inFIG.4(b)toward position P6. In addition, the coating head56is also decelerated to stop at position P5 after reaching position P7 shown inFIG.4(b). It should be noted that the same is true when moving the coating head56along the backward path in the forward and backward movement in the main scanning direction, and when the coating head56is moved from position P5 toward position P7, it is accelerated at position P7 to achieve the desired movement speed, and after reaching position P6, it is slowed down to stop at position P5.

In this case, when the coating head56moves along the forward path in the forward and backward movement in the main scanning direction, position P4 is the coating start position and position P5 is the coating end position. Then, between position P6 and position P7, coating material dispensing is performed by multiple nozzles61of the coating head56. In addition, when the coating head56moves along the backward path in the forward and backward movement in the main scanning direction, position P5 is the coating start position and position P4 is the coating end position. Then, between position P7 and position P6, coating material dispensing is performed by multiple nozzles61of the coating head56.

FIG.9(a)is a diagram showing the change in pressure on the input side of the coating head56when the vehicle body FR is coated after the coating head56is stopped at position P4 for 5 seconds. In addition,FIG.9(b)is a diagram showing the change in pressure on the output side of the coating head56when the vehicle body FR is coated after the coating head56is stopped at position P4 for 5 seconds. Moreover, in this case as well, the target pressure on the input side of the coating head56is 0.1 bar, and the target pressure on the output side of the coating head56is -0.1 bar.

As shown inFIG.9(a), the pressure of the coating material at the input side of the coating head56is changing within a range of 0.0875 bar to 0.1125 bar. In addition, as shown inFIG.9(b), the coating material pressure at the output side of the coating head56is changing within a range of -0.11 bar to -0.0875 bar. As shown inFIGS.7(a) and7(b), when coating of the vehicle body FR is performed by deceleration when the coating head56reaches position P4 from position P1, the coating material pressure at the input side of the coating head56is changing within a range of 0.0875 bar to 0.1125 bar. In addition, the pressure of the coating material at the output side of the coating head56is changing within a range of -0.10875 bar to -0.0875 bar.

After stopping the coating head56at position P4 for 5 seconds, the posture of the robot arm15is changed in order to move the coating head56when coating is performed, so it was found that the pressure of the coating material associated with the change in the posture of the robot arm15changes when coating by the coating head56is started, but the pressure of the coating material on the input side and output side of the coating head56is suppressed compared to the case of coating the vehicle FR at position P4. Therefore, it can also be found that reducing pressure fluctuations in the interior of the coating material circulation device51associated with the movement of the coating head56is effective by coating the vehicle body FR while moving the coating head56at a speed lower than the movement speed when moving the coating head56to the position P4 after moving the coating head56to position P4 and stopping it for a predetermined time at that position P4.

It should be noted that while we explained the case of moving along the forward path in the main scanning direction after stopping the coating head56at position P4 for a predetermined time, it is also possible to stop the coating head56at position P5 for a predetermined time in the same manner when moving along the backward path in the main scanning direction. At this time, the coating head56will be moved a predetermined distance in the sub-scanning direction when switching from the movement along the backward path in the main scanning direction to the movement along the forward path in the main scanning direction, but the speed when moving the coating head56in the sub-scanning direction may be either slower than the movement speed when coating the vehicle body FR or faster than the movement speed when coating the vehicle body FR. In addition, when coating multiple vehicle body FR simultaneously using multiple coating robots10, or when coating one vehicle body FR using multiple coating robots10, there is a possibility that the coating head56provided in each robot arm15will collide when each robot arm15is driven. To prevent, for example, collisions of the coating head56provided on each robot arm15, the movement speed of the coating head56may be varied before and after the retraction position if there is a retraction position in the movement trajectory of the coating head56from the end of the movement along the forward path in the main scanning direction until the movement along the backward path in the main scanning direction begins (or vice versa).

In this embodiment, the movement speed of the coating head56is slowed down or stopped temporarily at position P4 prior to reaching position P4 so that the pressure changes that occur with the movement of the coating head56by the robot arm15do not affect the coating of the vehicle body FR by the coating head56. However, in the coating of the vehicle body FR using the coating robot10, the drive of the robot arm15may cause the coating head56to vibrate and cause the coating material to be ejected from the multiple nozzles61provided at the nozzle forming surface56aof the coating head56to shift the landing position. In order to prevent such an event, it is also possible to provide a means for detecting vibration in the second rotary arm and a means for imparting vibration to the second rotary arm that offsets the vibration detected by the said detection means or imparts vibration that is in reverse phase of the detected vibration.

Effects

The robot10for coating the vehicle body of this invention has a coating head56that dispenses coating material onto the vehicle body FR; a coating material circulation device51that has a supply path57and a return flow path58for circulating the coating material between a coating material tank55for storing the coating material and a coating head56, and that is capable of controlling the pressure of the coating material flowing in the circulation path comprising the supply path57and the return flow path58; and a robot arm15having a coating head56and a coating material circulation device51; and the coating of the vehicle body FR is performed while the coating head56is moved in the main scanning direction by the movement of the robot arm15; it has an arm control unit102for controlling operation of the robot arm15; and the coating head56moves at a first speed toward the coating start position (position P4) where the coating of the vehicle body FR is started by the movement of the arm by the control means, and when it reaches a specific position (position P2) provided in the movement path to the coating start position, it moves at a second speed different from the first speed.

For example, the coating head56is held in a preset initial position (position P1) when the vehicle body FR is not coated, and when a new vehicle body FR is coated, the robot arm15moves from the initial position toward the coating start position. Moreover, when operation of the robot arm15is started, the coating material circulation device51and coating head56provided in the robot arm15are affected by the acceleration at the start of operation of the robot arm15, and the pressure of the coating material flowing through the supply path57and return flow path58of the coating material circulation device51varies. In addition, at the same time, the robot arm15itself also vibrates. As a result, the supply of coating material to the coating head56becomes unstable, causing variations in the amount of coating material dispensed from the multiple nozzles61provided on the coating head56. In addition, this can also cause the landing position of the coating material dispensed with multiple nozzles or61provided on the coating head56to become disordered.

In this invention, when the coating head56is moved, for example, to a specific position (position P2) provided in the movement path of the coating head56from the initial position to the coating start position, the movement speed of the coating head56is changed to a different movement speed to move to the coating start position. Such control can converge the pressure fluctuations of the coating material flowing through the coating material circulation device51and the vibrations of the robot arm15itself while the coating head56moves to the coating start position. This not only stabilizes the coating material supply to the coating head56and prevents variations in the amount of coating material ejected from the multiple nozzles61provided on the coating head56but also inhibits disorder of the landing position of the coating material ejected from the multiple nozzles61provided on the coating head56. As a result, in the coating of the vehicle body FR by the coating head56, deterioration of the coating quality can be inhibited.

It should be noted that by setting the second speed below the first speed or setting the first speed below the second speed, the change in coating material pressure associated with the change in movement speed can be prevented from affecting coating by the coating head56.

Also, the coating head56starts coating the vehicle body FR while maintaining the second speed when the coating start position is reached.

According to this configuration, the movement speed of the coating head56after passing through a specific position is maintained constant. In other words, the impact of pressure fluctuations caused by deceleration at a specific position is suppressed at the coating start position, and it is possible to coat the vehicle body FR while maintaining that state. As a result, in the coating of the vehicle body FR by the coating head56, deterioration of the coating quality can be inhibited.

In addition, the coating head56moves forward and backward multiple times in the main scanning direction and moves a predetermined amount in a sub-scanning direction orthogonal to the main scanning direction upon switching the forward and backward movement in the main scanning direction; and the coating start position is provided at each of the forward path and backward path in a forward and backward movement of the main scanning direction.

According to this invention, during the switching of forward and backward movement in the main scanning direction, the change in pressure during the shifting in the sub-scanning direction orthogonal to the main scanning direction and the vibrations caused by the change in the posture of the robot arm15can be prevented from affecting the coating using the coating head56.

At this time, the coating head56is moved at a third speed that is slower than the second speed when moving a predetermined amount in the sub-scanning direction.

According to this invention, the change in pressure when moving a predetermined amount in a sub-scanning direction orthogonal to the main scanning direction can be reduced, so coating using the coating head56can be performed stably.

In addition, the robot10for coating the vehicle body of this invention has a coating head56that dispenses coating material onto the vehicle body FR; a coating material circulation device51that has a supply path57and a return flow path58for circulating the coating material between a coating material tank55for storing the coating material and a coating head56, and that is capable of controlling the pressure of the coating material flowing in the circulation path comprising the supply path57and the return flow path58; and a robot arm15having a coating head56and a coating material circulation device51; and the coating of the vehicle body FR is performed while the coating head56is moved in the main scanning direction by the movement of the robot arm15; it has an arm control unit102for controlling operation of the robot arm15; the coating head56is moved to the coating start position (position P6) where the coating of the vehicle body FR is started by control of the robot arm15by the arm control unit102, stopped temporarily and then resumes movement from the coating start position to the main scanning direction after a predetermined time has elapsed after stopping at the coating start position to perform coating of the vehicle body FR, and the movement speed of the coating head56when coating the vehicle body FR is set to a movement speed different from the movement speed of the coating head56when moving to the coating start position.

For example, when operation of the robot arm15is initiated, the coating material circulation device51and coating head56provided in the robot arm15are affected by acceleration at the start of operation of the robot arm15, causing the pressure of the coating material flowing through the supply path57and return flow path58of the coating material circulation device51to vary. In addition, at the same time, the robot arm15itself also vibrates. As a result, the supply of coating material to the coating head56becomes unstable, causing variations in the amount of coating material dispensed from the multiple nozzles61provided on the coating head56. In addition, the landing position of the coating material dispensed from the multiple nozzles61provided on the coating head56is disrupted.

In this invention, the coating head56moved from the initial position to the coating start position is temporarily stopped at the coating start position to converge the pressure fluctuation of the coating material flowing through the coating material circulation device51and the vibration of the robot arm15itself. Coating head56stopped at coating start position will start coating after a certain period of time has elapsed. At this time, the coating head56will move along the main scanning direction from the coating start position, but the movement speed is set to be slower than the movement speed of the coating head56from the initial position to the coating start position. Thus, the pressure variation of the coating material flowing through the coating material circulation device51is less than the pressure variation when the coating head56moves from the initial position toward the coating start position. This can stabilize coating material supply to the coating head56and not only reduce the variation in the amount of coating material dispensed from the multiple nozzles61provided on the coating head56but also reduce disorder of the landing position of the coating material dispensed from the multiple nozzles61provided on the coating head56. As a result, in the coating of the vehicle body FR by the coating head56, deterioration of the coating quality can be suppressed.

In addition, the coating head56moves forward and backward multiple times in the main scanning direction and moves a predetermined amount in a sub-scanning direction orthogonal to the main scanning direction upon switching the forward and backward movement in the main scanning direction; the coating start position is provided at each of the forward path and backward path in a forward and backward movement in the main scanning direction; and the coating head is temporarily stopped at the coating start position provided at each of the forward path and backward path.

According to this invention, it is possible to stabilize the coating material supply to the coating head56and not only reduce the variation in the amount of coating material dispensed from the multiple nozzles61provided on the coating head56but also reduce disorder of the landing position of the coating material dispensed from the multiple nozzles61provided on the coating head56. As a result, in the coating of the vehicle body FR by the coating head56, deterioration of the coating quality can be suppressed.

In addition, the coating head56is held at the initial position when the coating of the vehicle body FR is not being performed, and the arm control unit102is to control the operation of the robot arm15in response to the start of coating on the vehicle body FR to move the coating head56from the initial position to the coating start position.

According to this configuration, when the vehicle body FR is not coated, the coating head56is held at an initial position away from the vehicle body FR, so that the occurrence of events such as contact of the coating head56with the coated body or the uncoated body FR can be prevented.

In addition, it also includes a supply path57that supplies coating material stored in a coating material tank55to a coating head56, a return flow path58that returns coating material not used by the coating head56to the coating material tank55, and the coating material circulation device51includes a gear pump62that pumps coating material stored in the coating material tank55to the supply path57, a gear pump80that draws coating material from the coating head56to the return flow path58, a pressure gauge69that detects the pressure of coating material dispensed to the supply path57, a pressure gauge79that detects the pressure of coating material drawn to the return flow path58, and a coating material supply control unit103for controlling the dispensing amount of the coating material by the gear pump62based on a detection result by the pressure gauge69and for controlling the drawing amount of the coating material by the gear pump80based on a detection result by the pressure gauge79.

According to this invention, during operation of the robot arm15, the gear pumps62,80can be controlled based on the pressure of the coating material fed into the supply path57of the coating material circulation device51and the pressure of the coating material drawn into the return flow path58, so that the pressure of the coating material in each flow path can be kept at the proper pressure. That is, the supply of coating material to the coating head56by the coating material circulation device51can be stably performed.

DESCRIPTION OF REFERENCE NUMERALS

10... coating robot (robot for coating a vehicle body )15... robot arm21... base (base unit)22... first rotary arm23... second rotary arm51... coating material circulation device (supply device)55... coating material tank (reservoir)56... coating head57... supply path58... return flow path (reflux path)62... gear pump (dispensing method)69... pressure gauge (first detection means)79... pressure gauge (second detection means)80... gear pump (retraction means)102... arm control unit (control means)103... coating material supply control unit (pressure control means)