Patent Description:
In painting lines of automobiles and other vehicles, robot painting using robots has become the mainstream. In such robot painting, a painting machine (rotary atomizing type painting machine) in which a rotary atomizing type painting head is mounted at the front end of a multi-joint robot is used. However, as disclosed in Patent Literature <NUM>, it is proposed to use an injection type painting machine for painting a vehicle. In addition, for example, Patent Literature <NUM> discloses painting with a spray pattern of a lengthy shape.

D1 <CIT> describes a print head comprising a nozzle plate with at least one nozzle for ejecting ink by driving a valve element.

D2 <CIT> describes a print head comprising a plurality of nozzles for applying a coating agent such as paint.

Meanwhile, when driving an injection type nozzle head, heat is generated near the driving portion (piezoelectric substrate) thereof. If temperature rises due to such heat generation, the electrical characteristics may change in the characteristics of the electrically conductive parts including the piezoelectric substrate and the like, causing misoperation, damage and the like.

In addition, paint discharged from nozzles of the nozzle head changes its viscosity and other characteristics due to heat, which may lead to the deterioration of vehicle painting quality. Furthermore, although some paints contain organic solvents, it is not desirable for the temperature of the nozzle head to rise significantly when such paints containing organic solvents are being discharged.

Given the above-mentioned situation, the present disclosure has been made to provide a painting robot capable of suppressing the temperature rise of the nozzle head to be less than or equal to a constant temperature.

In order to solve the above problems, according to a first perspective of the present disclosure, it provides a painting robot configured to discharge paint towards the painting object from nozzles to perform painting, which is characterized by including: a nozzle head including a plurality of nozzles and discharging paint from the nozzles by driving of a piezoelectric substrate; a power supplier for supplying power for driving the piezoelectric substrate; and a robot arm with a front end to which the nozzle head can be mounted and moving the mounted nozzle head; wherein the nozzle head is provided, in a state in which the nozzle discharging surface thereof is exposed to the outside, within an explosion-proof housing that covers the portions other than the nozzle discharging surface, within the explosion-proof housing, a heat-release unit which release the heat generated from the nozzle head is mounted to the nozzle head, and within the explosion-proof housing, a temperature measuring unit which measures the temperature of the heat-release unit is mounted to the heat-release unit, wherein the painting robot is provided with a power cut-off device which, in response to the temperature measuring unit detecting that a predetermined temperature has been reached, cuts off the power supply from the power supplier to the piezoelectric substrate based on the detection signal from the temperature measuring unit.

In addition, in the above disclosure, it is preferable that the explosion-proof housing has an internal pressure explosion-proof structure in which the internal pressure of the internal space thereof is higher than the pressure of the external atmosphere.

In addition, in the above disclosure, it is preferable that the explosion-proof housing has a pressure-resistant explosion-proof structure consisting of a pressure-resistant material.

In addition, in the above disclosure, it is preferable that the heat-release unit is a heat-release plate, and the heat-release plate is mounted to the side surface of the nozzle head intersecting with the nozzle discharging surface.

In addition, in the above disclosure, it is preferable that the explosion-proof housing includes a gas supplier mounted to a gas introduction opening formed in the explosion-proof housing, and a gas exhauster mounted to a gas exhaust opening formed in the explosion-proof housing, inactive gas is introduced from the gas supplier and exhausted from the gas exhauster.

In addition, in the above disclosure, it is preferable that the explosion-proof housing is provided with a cylindrical portion and an expanded portion expanded in a state that its size in the width direction is larger than the outer peripheral surface of the cylindrical portion, and the gas supplier is mounted on the expanded outer peripheral wall of the expanded portion facing the heat-release unit, so that the gas supplier sprays inactive gas towards the heat-release unit.

In addition, in the above disclosure, it is preferable that the gas exhauster is a gas control valve which is capable of adjusting the flow rate of inactive gas, and the gas control valve is mounted in the internal space of the explosion-proof housing and on the wall surface of the explosion-proof housing opposite to the gas supplier across the nozzle head.

In addition, in the above disclosure, it is preferable that it is provided with a controller that controls the operation of the gas control valve and controls the flow rate of the inactive gas exhausted from the gas control valve so that the internal pressure of the internal space is higher than the pressure of the external atmosphere.

According to the present disclosure, it is possible to provide a painting robot capable of suppressing the temperature rise of the nozzle head to be less than or equal to a constant temperature.

Hereinafter, painting robots of the embodiments of the present disclosure are described with reference to the drawings. Additionally, in the following description, X direction is set to the long direction of the nozzle discharging surface <NUM> (nozzle head <NUM>), the X1 side is the right side in <FIG>, and the X2 side is the left side in <FIG> as needed. In addition, Y direction is set to the short direction (width direction) of the nozzle discharging surface <NUM> (nozzle head <NUM>), the Y1 side is the upper side in <FIG>, and the Y2 side is the lower side in <FIG>.

The painting robot according to the present embodiment " coats" an painting object, such as a vehicle or a vehicle part (hereinafter, a vehicle part that is a part of a vehicle is also described as a vehicle), which is located in a painting line of an automobile manufacturing plant, and it is aimed at forming a painting film on the surface of the painting object, providing its surface with protection and aesthetics. Therefore, it is necessary to coat approaching vehicles moving along the painting line every prescribed time with desired painting quality within a certain time period.

In addition, in the painting robot of the present embodiment, not only the above-mentioned painting film can be formed, but also various designs and images can be formed on painting objects such as vehicles and vehicle parts.

<FIG> is a schematic diagram showing the overall structure of a painting robot <NUM> according to the first embodiment of the present disclosure. As shown in <FIG>, the main components of the painting robot <NUM> include a robot body <NUM> and a nozzle head unit <NUM>.

As shown in <FIG>, the main components of the robot body <NUM> include a base <NUM>, a leg portion <NUM>, a rotating shaft portion <NUM>, a rotating arm <NUM>, a first revolving arm <NUM>, a second revolving arm <NUM>, a wrist portion <NUM>, and a motor (not shown) for driving them. Additionally, although the portion from the rotating shaft portion <NUM> to the wrist portion <NUM> corresponds to the robot arm R1, other portions such as the leg portion <NUM> may also correspond to the robot arm R1.

Among those, although the base <NUM> is a portion set at a setup location such as a floor face, the base <NUM> may also be travelable relative to the setup location. In addition, the leg portion <NUM> is a portion vertically arranged from the base <NUM> toward the upper side. Further, a joint portion may be provided between the leg portion <NUM> and the base <NUM> so that the leg portion <NUM> is revolvable relative to the base <NUM>.

In addition, the rotating shaft portion <NUM> is provided at the upper end of the leg portion <NUM>. The rotating arm <NUM> is mounted to the rotating shaft portion <NUM> in a rotatable state. In addition, the rotating arm <NUM> rotates through the drive of a motor (first motor) and an electric motor or a pneumatic motor may be used as the motor. In addition, when the painting robot <NUM> is arranged in an explosion-proof area and an electric motor is used, it is preferable to take an explosion-proof measure, such as increasing the internal pressure in the housing of the rotating shaft portion <NUM> (using an internal pressure explosion-proof structure) (the same shall apply for the following electric motors (the second to sixth motors)). However, when the painting robot <NUM> is arranged in a location other than an explosion-proof area, the above explosion-proof measures may not be taken. Further, the explosion-proof structure in the vicinity of the nozzle head <NUM> will be described hereinafter.

In addition, one end side of the first revolving arm <NUM> is mounted to the rotating arm <NUM> in a revolvable state. Further, a second motor (not shown) that rotates the first revolving arm <NUM> relative to the rotating shaft portion <NUM> may be accommodated in the housing of the rotating arm <NUM> or may be accommodated in the housing of the first revolving arm <NUM>.

In addition, one end side of the second revolving arm <NUM> is mounted to the other end side of the first revolving arm <NUM> via a shaft portion in a swingable state. A third motor (not shown) that rotates the second revolving arm <NUM> relative to the first revolving arm <NUM> may be accommodated in the housing of the first revolving arm <NUM> or may be accommodated in the housing of the second revolving arm <NUM>.

The wrist portion <NUM> is mounted to the other end side of the second revolving arm <NUM>. The wrist portion <NUM> is capable of rotational movement around a plurality of (e.g. three) shaft portions in different directions. Thereby, the direction of the nozzle head unit <NUM> can be accurately controlled. Further, the number of shaft portions may be any number as long as it is more than or equal to two.

Motors (the fourth to sixth motors; not shown) are provided for enabling the rotational movement of such wrist portion <NUM> around respective shaft portions. Further, although the fourth to sixth motors are accommodated in the housing of the second revolving arm <NUM>, it may be accommodated in other locations.

In addition, the nozzle head unit <NUM> is mounted to the wrist portion <NUM> via a holder portion (not shown). That is to say, the nozzle head unit <NUM> is detachably provided to the wrist portion <NUM> via the holder portion.

Further, the painting robot <NUM> including the rotating shaft portion <NUM>, the rotating arm <NUM>, the first revolving arm <NUM>, the second revolving arm <NUM>, the wrist portion <NUM> and the first to sixth motors for driving them is a robot that can be driven in six axes. However, the painting robot <NUM> can be a robot driven in any number of axes, as long as it has four or more axes.

Next, the nozzle head unit <NUM> will be described. The nozzle head unit <NUM> is mounted to the wrist portion <NUM> via a chuck portion (not shown). As shown in <FIG>, the nozzle head unit <NUM> includes an explosion-proof housing <NUM> described later and various structures are built in the explosion-proof housing <NUM>. Further, the structures built in the explosion-proof housing <NUM> for example includes a head side circulation path (not shown) which is a path for paint circulation, a head control portion <NUM> and the like.

<FIG> shows the nozzle discharging surface <NUM> which discharges paint in the nozzle head unit <NUM> from the front. As shown in <FIG>, the nozzle discharging surface <NUM> is provided with a plurality of nozzle columns <NUM> in which the nozzles <NUM> are lining up in a direction inclined to the width direction of the nozzle head unit <NUM>. In the present embodiment, a first nozzle column 55A located on one side (Y2 side) of the main scanning direction (Y direction) and a second nozzle column 55B (Y1 side) located on the other side of the main scanning direction are provided in such nozzle column <NUM>.

Further, when discharging paint, the driving timings of the nozzles <NUM> are controlled so that droplets discharged from the nozzles <NUM> in the second nozzle column 55B impact between droplets discharged from adjacent nozzles <NUM> in the first nozzle column 55A. Thereby, the point density can be increased during painting.

Meanwhile, as shown in <FIG>, a single nozzle head <NUM> is present on the nozzle discharging surface <NUM>. However, a head group consisting of a plurality of nozzle heads <NUM> may be present on the nozzle discharging surface <NUM>. In this case, as shown in <FIG>, although as an example, a structure in which the plurality of nozzle heads <NUM> are aligned and arranged in a staggered shape are illustrated, the arrangement of the nozzle heads <NUM> in the head group may not be in a staggered shape.

<FIG> shows the schematic structure supplying paint to each nozzle <NUM>. <FIG> is a sectional view showing the structure in the vicinity of the column-direction supply flow path <NUM>, the nozzle pressurizing chamber <NUM>, and the column-direction exhaust flow path <NUM>. As shown in <FIG> and <FIG>, the nozzle head <NUM> includes a supply side large flow path <NUM>, a column-direction supply flow path <NUM>, a nozzle pressurizing chamber <NUM>, a column-direction exhaust flow path <NUM>, and an exhaust side large flow path <NUM>. The supply side large flow path <NUM> is a flow path through which paint from the supply path <NUM> of the head side circulation path described later. In addition, the column-direction supply flow path <NUM> is a flow path through which the paint in the supply side large flow path <NUM> is diverted.

In addition, the nozzle pressurizing chamber <NUM> is connected to the column-direction supply flow path <NUM> via the nozzle supply flow path 59a. Thereby, paint is supplied from the column-direction supply flow path <NUM> to the nozzle pressurizing chamber <NUM>. The nozzle pressurizing chamber <NUM> is provided corresponding to the number of nozzles <NUM> and the paint therein can be discharged from the nozzles <NUM> using a driving element described later.

In addition, the nozzle pressurizing chamber <NUM> is connected to the column-direction exhaust flow path <NUM> via a nozzle exhaust flow path (not shown). Therefore, paint not discharged from the nozzles <NUM> is exhausted from the nozzle pressurizing chamber <NUM> to the column-direction exhaust flow path <NUM> via the nozzle exhaust flow path. In addition, the column-direction exhaust flow path <NUM> is connected to the exhaust side large flow path <NUM>. The exhaust side large flow path <NUM> is a flow path in which the paint exhausted from respective column-direction exhaust flow paths <NUM> converges. The exhaust side large flow path <NUM> is connected to the return path <NUM> of the head side circulation path.

With this structure, the paint supplied from the supply path <NUM> of the head side circulation path is discharged from the nozzles <NUM> via the supply side large flow path <NUM>, the column-direction supply flow path <NUM>, the nozzle supply flow path 59a, and the nozzle pressurizing chamber <NUM>. In addition, paint not discharged from the nozzles <NUM> passes through the nozzle exhaust flow path, the column-direction exhaust flow path <NUM> and the exhaust side large flow path <NUM> from the nozzle pressurizing chamber <NUM>, and returns to the return path <NUM> of the head side circulation path.

Further, in the structure shown in <FIG>, one column-direction exhaust flow path <NUM> is arranged corresponding to one column-direction supply flow path <NUM>. However, a plurality of (e.g. two) column-direction exhaust flow paths <NUM> may also be arranged corresponding to one column-direction supply flow path <NUM>. In addition, one column-direction exhaust flow path <NUM> may also be arranged corresponding to a plurality of column-direction supply flow paths <NUM>.

In addition, as shown in <FIG>, the piezoelectric substrate <NUM> is arranged on the top surface (the surface opposite to the nozzles <NUM>) of the nozzle pressurizing chamber <NUM>. The piezoelectric substrate <NUM> includes two piezoelectric ceramic layers 63a and 63b which are piezoelectric bodies and includes a common electrode <NUM> and an individual electrode <NUM>. The piezoelectric ceramic layers 63a and 63b are members that can be expanded and contracted by applying a voltage from the outside. As such piezoelectric ceramic layers 63a and 63b, ceramic materials with ferroelectricity, such as lead zirconate titanate (PZT) based, NaNbO3 based, BaTiO3 based, (BiNa) NbO3 based and BiNaNb5O15 based materials, can be used.

In addition, as shown in <FIG>, the common electrode <NUM> is arranged between the piezoelectric ceramic layer 63a and the piezoelectric ceramic layer 63b. In addition, a surface electrode (not shown) for the common electrode is formed on the upper surface of the piezoelectric substrate <NUM>. The common electrode <NUM> and the surface electrode for the common electrode are electrically connected via a through conductor (not shown) present in the piezoelectric ceramic layer 63a. In addition, the individual electrodes <NUM> are respectively provided at positions facing the above nozzle pressurizing chambers <NUM>. Furthermore, a portion of the piezoelectric ceramic layer 63a sandwiched between the common electrode <NUM> and the individual electrode <NUM> is polarized in the thickness direction. Therefore, in response to applying a voltage to the individual electrode <NUM>, the piezoelectric ceramic layer 63a is strained due to the piezoelectric effect. For this reason, in response to applying a prescribed driving signal to the individual electrode <NUM>, the piezoelectric ceramic layer 63b varies relatively so as to reduce the volume of the nozzle pressurizing chamber <NUM>, thereby discharging the paint.

Further, although in the structure shown in <FIG>, the common electrode <NUM> is arranged on the top surface of the nozzle pressurizing chamber <NUM>, it is not limited to this structure. For example, as shown in <FIG>, the common electrode <NUM> may be arranged on the side surface of the nozzle pressurizing chamber <NUM>, and any other structure may be adopted as long as the paint can be well discharged from the nozzles <NUM>.

Next, other structures of the nozzle head unit will be described. <FIG> is a plan view showing the structure of a nozzle discharging surface <NUM> of a further nozzle head unit. As shown in <FIG>, a nozzle column <NUM> may be constituted by arranging a plurality of nozzles <NUM> in the short direction (width direction; Y direction) of the nozzle head <NUM>. Further, although in the structure shown in <FIG>, a nozzle column <NUM> is constituted by arranging a plurality of nozzles <NUM> in the short direction (width direction; the main scanning direction) of the nozzle head <NUM>, a structure in which only one (single) nozzle <NUM> is arranged in the short direction (width direction; the main scanning direction) of the nozzle head <NUM> may be adopted. That is to say, the nozzle column <NUM> may be constituted by one nozzle <NUM>.

In addition, when painting a vehicle using the nozzle head <NUM> shown in <FIG>, painting may be performed in a state in which the long direction of the nozzle head <NUM> is slightly inclined to the main scanning direction of the nozzle head <NUM>. For example, in the structure of the nozzle head <NUM> shown in <FIG>, the long direction of the nozzle head <NUM> may be inclined to the main scanning direction of the nozzle head <NUM> by an angle α if the nozzle column <NUM> is inclined to the main scanning direction by an angle α. With this inclination, the same painting as the nozzle head <NUM> shown in <FIG> can be achieved by only adjusting the discharging timing of the paint from the nozzles <NUM>.

Next, the detailed structure of the nozzle head unit <NUM> and the temperature sensor will be described. <FIG> is a sectional view showing the structure of the nozzle head unit <NUM>. <FIG> is a block diagram showing the electrical structure in the vicinity of the nozzle head unit <NUM>. As shown in <FIG> and <FIG>, the nozzle head unit <NUM> has an explosion-proof housing <NUM>.

The explosion-proof housing <NUM> has an internal space P1 sealed from the external atmosphere and adopts an internal pressure explosion-proof structure which increases the internal pressure of the internal space P1 thereof by supplying inactive gas from the gas supply coupling <NUM> (the internal pressure of the internal space P1 is higher than the pressure of the external atmosphere). In addition, the internal space P1 of the explosion-proof housing <NUM> is sealed so as to prevent ignition of the external atmosphere through all the junction portions and opening portions isolating the internal space P1. In addition, by keeping the pressure of the non-flammable inactive gas in the internal space P1 higher than the pressure of the external atmosphere, the flammable gas for pressurizing in the external atmosphere is prevented from invading the internal space P1. With this structure which increases the internal pressure, the explosion-proof performance of the explosion-proof housing <NUM> is also ensured.

Here, a cylindrical portion <NUM> covering the above internal space P1, an expanded portion <NUM> and a front cover <NUM> are present in the explosion-proof housing <NUM>. Among those, the cylindrical portion <NUM> is a portion configured in a cylindrical shape (e.g. a rectangular cylindrical shape) in which portions with the same width (cross-sectional area) are continuous. However, a part of the width (cross-sectional area) of the cylindrical portion <NUM> may also be different. Further, the cylindrical portion <NUM> includes various shapes such as a rectangular shell, a round cylindrical shell and the like.

In addition, the expanded portion <NUM> is the part which has an expanded portion whose width (cross-sectional area) is expanded compared to the cylindrical portion <NUM>, and the nozzle head <NUM> is arranged on the expanded portion <NUM> using such expansion. In addition, the front cover <NUM> is mounted on the opening side of the expanded portion <NUM>. That is to say, the front cover <NUM> is mounted to an opening portion of the explosion-proof housing <NUM> away from the wrist portion <NUM>. And the nozzle head <NUM> is mounted through the front cover <NUM>. That is to say, the front cover <NUM> is provided with an opening portion for mounting (not shown), and the nozzle head <NUM> is mounted to the front cover <NUM> in a state in which the nozzle discharging surface <NUM> of the nozzle head <NUM> is exposed from the opening portion for mounting.

In addition, the explosion-proof housing <NUM> is provided with a gas introduction opening <NUM> and the gas supply coupling <NUM> is mounted to the gas introduction opening <NUM>. The gas introduction opening <NUM> is provided in the expanded outer peripheral wall 72a in the above-mentioned expanded portion <NUM>. Here, the expanded outer peripheral wall 72a is the wall surface facing the nozzle head <NUM> in <FIG>. However, although the expanded outer peripheral wall 72a is a wall surface which face the top surface of the nozzle head <NUM> at a prescribed angle instead of facing it parallelly, it may also be formed so as to face the top surface of the nozzle head <NUM> parallelly. Further, although the gas supply coupling <NUM> corresponds to the gas supplier, at least one of the pressurizing pipeline <NUM> and the pressurizer <NUM> other than the gas supply coupling <NUM> may also correspond to the gas supplier.

By providing the expanded outer peripheral wall 72a with the gas introduction opening <NUM>, the gas supply coupling <NUM> can spray inactive gas towards the nozzle head <NUM>. Further, in the state in which the piezoelectric substrate <NUM> is operating (heating state), inactive gas is maintained at a temperature sufficiently lower than the heat-release plate <NUM> described later.

In addition, a pressurizing pipeline <NUM> shown in <FIG> is connected to the gas supply coupling <NUM>, and a pressurizer <NUM> such as a compressor is connected to the pressurizing pipeline. Further, in <FIG>, the gas introduction opening <NUM> is disposed in the vicinity of the nozzle head <NUM> and inactive gas can be supplied towards the nozzle head <NUM>.

In addition, the explosion-proof housing <NUM> is provided with a gas exhaust opening <NUM>. A gas control valve <NUM> such as a proportional control valve is mounted to the gas exhaust opening <NUM>. In addition, the gas control valve <NUM> corresponds to the gas exhauster. With such a gas control valve <NUM>, the flow rate of exhausting inactive gas can be adjusted to adjust the pressure of the internal space P1.

Here, the gas control valve <NUM> is mounted in the internal space P1 of the explosion-proof housing <NUM> and on the wall surface of the explosion-proof housing <NUM> opposite to the gas supply coupling <NUM> across the nozzle head <NUM>. As an example of the mounting position of such a gas control valve <NUM>, although <FIG> shows a case where the gas control valve <NUM> is mounted closer to the ceiling surface <NUM> away from the nozzle discharging surface <NUM> than the center of the internal space P1, the mounting position of the gas control valve <NUM> is not limited thereto and may be any position as long as it is a wall surface of the explosion-proof housing <NUM> opposite to the gas supply coupling <NUM> across the nozzle head <NUM>. In addition, if the cooling performance of the nozzle head <NUM> can be sufficiently ensured, the gas control valve <NUM> may also be mounted on the wall surface of the explosion-proof housing <NUM> on the same side as the gas supply coupling <NUM> with respect to the nozzle head <NUM>.

As shown in <FIG> and <FIG>, the heat-release plate <NUM> is mounted to the nozzle head <NUM>. The heat-release plate <NUM> is mounted to the side surface 53a of the nozzle head <NUM> which is the surface intersecting with the nozzle discharging surface <NUM>. Thereby, heat generated from the nozzle head <NUM> can be released in a relatively large area. Further, the heat-release plate <NUM> corresponds to the heat-release unit.

Further, since there are two side surfaces 53a, it is preferable to mount heat-release plates <NUM> on respective side surfaces 53a. However, if sufficient heat release performance can be obtained with one heat-release plate <NUM>, it may also be mounted on only one of the two side surfaces 53a. In addition, the heat-release plate <NUM> may also be mounted on the top surface 53B opposite to the nozzle discharging surface <NUM>.

In addition, although the heat-release plate <NUM> is made of an aluminum-based metal having better thermal conductivity than iron or the like and having excellent machining performance, copper having better thermal conductivity than aluminum-based metals may also be adopted. In addition, it may also be configured to have a plurality of fins for increasing the surface area of the heat-release plate <NUM>.

In addition, a temperature sensor <NUM> is mounted to the heat-release plate <NUM> and the temperature sensor <NUM> measures the temperature of the heat-release plate <NUM>. Further, the temperature sensor <NUM> may be for example a PTC (Positive Temperature Coefficient) thermistor, an NTC (Negative Temperature Coefficient) thermistor, a thermocouple, an RTD (Resistance Temperature Detector), a semiconductor temperature sensor, and the like. Further, the temperature sensor <NUM> corresponds to the temperature measuring unit.

The temperature sensor <NUM> is connected to a circuit breaker <NUM> outside the explosion-proof housing <NUM> via a signal line not shown. The circuit breaker <NUM> cuts off the power supply to the nozzle head <NUM> and is mounted to power lines before and after the power supply circuit <NUM> (in <FIG>, the main control portion <NUM> away from the nozzle head <NUM>) which supplies power for driving to the driving driver <NUM>. Further, the power supply circuit <NUM> corresponds to the power supplier. Further, the circuit breaker <NUM> corresponds to the power cut-off device.

In response to the above temperature sensor <NUM> detecting that the temperature of the nozzle head <NUM> (heat-release plate <NUM>) is greater than or equal to a predetermined temperature, the circuit breaker <NUM> operates to force the power supply to the nozzle head <NUM> to stop. Thereby, the temperature of the nozzle head <NUM> is prevented from rising above the predetermined temperature.

Further, as shown in <FIG>, the painting robot <NUM> is provided with a main control portion <NUM>, the main control portion <NUM> transmits predetermined control signals to the head control portion <NUM>, the valve control portion <NUM> and the pressurizer control portion <NUM> so that all the portions of the painting robot <NUM> cooperate to coat a painting object. Further, although the main control portion <NUM> and the valve control portion <NUM> constitute the controller, the control unit may be constituted by at least one of the main control portion <NUM>, the valve control portion <NUM> and the pressurizer control portion <NUM>.

Further, in the structure shown in <FIG>, the above-mentioned circuit breaker <NUM> is disposed between the main control portion <NUM> and the power supply circuit <NUM>. Therefore, in response to the operation of the circuit breaker <NUM>, since the power supply to the power supply circuit <NUM> is forced to stop, power is not supplied to the driving driver <NUM> for driving the nozzle head <NUM>. Therefore, the driving of the piezoelectric substrate <NUM> is stopped. However, a controller different from the structure shown in <FIG> may be configured. For example, the above-mentioned circuit breaker <NUM> may be disposed at least one of between the main control portion <NUM> and the head control portion <NUM>, between the power supply circuit <NUM> and the driving driver <NUM> and between the head control portion <NUM> and the driving driver <NUM>.

Further, the main control portion <NUM>, the head control portion <NUM>, the valve control portion <NUM> and the pressurizer control portion <NUM> include a CPU, a memory (ROM, RAM, non-volatile memory, etc.), and other elements. In addition, programs and data for executing the desired control is stored in the memory.

Here, the head control portion <NUM> transmits control signals related to images to the driving driver <NUM> based on instructions from the main control portion <NUM>. In addition, the valve control portion <NUM> controls the operation of the gas control valve <NUM> based on instructions from the main control portion <NUM>. In addition, the pressurizer control portion <NUM> controls the operation of the pressurizer <NUM> based on instructions from the main control portion <NUM>. In addition, the driving driver <NUM> controls application of power for driving the piezoelectric substrate <NUM> within the nozzle head <NUM> based on instructions from the head control portion <NUM>.

Next, the functions of the painting robot <NUM> having the above-mentioned structure will be described below. Here, the head control portion <NUM> transmits control signals related to images to the driving driver <NUM> based on instructions from the main control portion <NUM>. In addition, the head control portion <NUM> transmits control signals related to images for painting to the driving driver <NUM> based on instructions from the main control portion <NUM>. Then, by driving the piezoelectric substrate <NUM>, the temperature of the nozzle head <NUM> rises.

Here, the heat-release plate <NUM> is mounted to the nozzle head <NUM>. Therefore, the heat generated by the nozzle head <NUM> is released from the heat-release plate <NUM> to the internal space P1. Further, inactive gas is supplied from the gas supply coupling <NUM> to the internal space P1. Moreover, the gas supply coupling <NUM> is mounted to the expanded outer peripheral wall 72a and inactive gas is sprayed towards the heat-release plate <NUM>. Therefore, the heat-release plate <NUM> is easily cooled by inactive gas.

Further, inactive gas in the internal space P1 is exhausted from the gas control valve <NUM> mounted to the gas exhaust opening <NUM>. Here, by controlling the gas control valve <NUM> by the valve control portion <NUM>, the flow rate of the inactive gas exhausted from the internal space P1 is adjusted. Thereby, the pressure of the internal space P1 is for example adjusted to be higher than the pressure of the external atmosphere.

Here, the temperature sensor <NUM> is mounted to the heat-release plate <NUM> and the temperature sensor <NUM> measures the temperature of the heat-release plate <NUM>. And in response to the temperature measured by the temperature sensor <NUM> reaching a temperature that is not suitable for driving the nozzle head <NUM> (predetermined temperature), a detection signal indicating that such predetermined temperature has been reached is transmitted to the circuit breaker <NUM>. Then, the circuit breaker <NUM> immediately cuts off the power supply to the power supply circuit <NUM>. Thereby, the driving of the nozzle head <NUM> is forcibly stopped.

Further, although the above-mentioned predetermined temperature is higher than the temperature of the external atmosphere, the temperatures can be set to various values. As an example, it can be set to <NUM> degrees, <NUM> degrees, <NUM> degrees and <NUM> degrees. In addition, the predetermined temperature may be set to a temperature other than these temperatures.

The injection type painting robot <NUM> having the above configuration includes a nozzle head <NUM> including a plurality of nozzles and discharging paint from the nozzles <NUM> by driving of a piezoelectric substrate <NUM>; a power supplier (power supply circuit <NUM>) for supplying power for driving the piezoelectric substrate <NUM>; and a robot arm R1 with a front end to which the nozzle head <NUM> can be mounted and moving the mounted nozzle head <NUM>.

And the nozzle head <NUM> is provided, in a state in which the nozzle discharging surface <NUM> thereof is exposed to the outside, within an explosion-proof housing <NUM> that has an explosion-proof structure for covering the portions other than the nozzle discharging surface <NUM> and preventing damage even when an explosion occurs in the internal space P1, thereby preventing ignition of the external atmosphere. In addition, within the explosion-proof housing <NUM>, a heat-release unit (heat-release plate <NUM>) which release the heat generated from the nozzle head <NUM> is mounted to the nozzle head <NUM>, and within the explosion-proof housing <NUM>, a temperature measuring unit (temperature sensor <NUM>) which measures the temperature of the heat-release unit (heat-release plate <NUM>) is mounted to the heat-release unit (heat-release plate <NUM>). In addition, it is provided with a power cut-off device (circuit breaker <NUM>) which cuts off the power supply from the power supplier (power supply circuit <NUM>) to the piezoelectric substrate <NUM>. In response to the temperature measuring unit (temperature sensor <NUM>) detecting that a predetermined temperature has been reached, the power cut-off device (circuit breaker <NUM>) cuts off the power supply to the power supplier (power supply circuit <NUM>) based on the detection signal from the temperature measuring unit (temperature sensor <NUM>).

Configured in this way, the temperature measuring unit (temperature sensor <NUM>) is mounted to the heat-release unit (heat-release plate <NUM>), and when the temperature measuring unit (temperature sensor <NUM>) is mounted to the heat-release unit (heat-release plate <NUM>) and In response to the temperature measuring unit (temperature sensor <NUM>) detecting that a predetermined temperature has been reached, the power cut-off device (circuit breaker <NUM>) cuts off the power supply to the power supplier (power supply circuit <NUM>). Therefore, the temperature rise of the nozzle head <NUM> can be suppressed to be less than or equal to the predetermined temperature (less than or equal to a constant temperature). Therefore, an abnormal temperature rise in the nozzle head <NUM> can be prevented.

Therefore, it is possible to prevent accidental explosion in the internal space P1 and the external atmosphere due to the above-mentioned temperature rise. In addition, the piezoelectric substrate <NUM> in the nozzle head <NUM> can be prevented from thermal runaway due to temperature rise. In addition, it can also prevent the paint viscosity from increasing and prevent the painting quality from reducing due to the above-mentioned temperature rise.

In addition, since the heat-release unit (heat-release plate <NUM>) is mounted to the nozzle head <NUM>, temperature rise in the internal space P1 can be suppressed.

In addition, since the nozzle head <NUM> is disposed in the internal space P1 of the explosion-proof housing <NUM>, it is possible to isolate the portions where the temperature rise is significant from the external atmosphere. Therefore, even if an explosion occurs in the internal space P1, or spark and the like occurs in an electrically driven portion such as the piezoelectric substrate <NUM>, the external atmosphere can be prevented from being influenced thereby.

In addition, in the above-mentioned embodiment, the explosion-proof housing <NUM> has an internal pressure explosion-proof structure in which the internal pressure of the internal space P1 thereof is higher than the pressure of the external atmosphere. With this structure, it is possible to well prevent the external atmosphere from flowing into the internal space P1. Thereby, the explosion-proof performance of the explosion-proof housing <NUM> can be improved.

In addition, in the above-mentioned embodiment, the heat-release unit is a heat-release plate <NUM>, and the heat-release plate <NUM> is mounted to the side surface 53a of the nozzle head <NUM> intersecting with the nozzle discharging surface <NUM>.

With this structure, the heat-release plate <NUM> having an equally large area can be mounted on the side surface 53a having a relatively large area. Therefore, the cooling performance of the nozzle head <NUM> can be improved.

In addition, in the present embodiment, the explosion-proof housing <NUM> includes a gas supplier (gas supply coupling <NUM>) mounted to a gas introduction opening <NUM> formed in the explosion-proof housing <NUM>, and a gas exhauster (gas control valve <NUM>) mounted to a gas exhaust opening <NUM> formed in the explosion-proof housing <NUM>. Then the inactive gas is introduced from the gas introduction opening <NUM> and exhausted from the gas exhauster (gas control valve <NUM>).

With this configuration, inactive gas is supplied from the gas supplier (gas supply coupling <NUM>) to the internal space P1 of the explosion-proof housing <NUM>, and the inactive gas is exhausted from the gas exhauster (gas control valve <NUM>). Therefore, inactive gas can circulate within the internal space P1 and heat released from the heat-release unit (heat-release plate <NUM>) can be well exhausted to the outside. Thereby, the cooling performance of the nozzle head <NUM> can be further improved.

In addition, in the present embodiment, the explosion-proof housing <NUM> is provided with a cylindrical portion <NUM> and an expanded portion <NUM> expanded in a state that its size in the width direction is larger than the outer peripheral surface of the cylindrical portion <NUM>. In addition, the gas supplier (gas supply coupling <NUM>) is mounted on the expanded outer peripheral wall 72a of the expanded portion <NUM> facing the heat-release unit (heat-release plate <NUM>), so that the gas supplier (gas supply coupling <NUM>) sprays inactive gas towards the heat-release unit (heat-release plate <NUM>).

With this structure, since the cylindrical portion <NUM> has a narrower width and a smaller cross-sectional area than the expanded portion <NUM>, the weight of the explosion-proof material (metal, resin or the like) used for the cylindrical portion <NUM> can be reduced. Therefore, the behavior of the robot arm R1 can be improved. In addition, since the gas introduction opening <NUM> can be formed in the expanded outer peripheral wall 72a of the expanded portion <NUM> due to the presence of the expanded portion <NUM>, fresh inactive gas (with relatively lower temperature than the internal space P1) may be sprayed from the gas supplier (gas supply coupling <NUM>) towards the heat-release unit (heat-release plate <NUM>). Thereby, the cooling performance of the nozzle head <NUM> can be improved.

In addition, in the present embodiment, the gas exhauster is a gas control valve <NUM> which is capable of adjusting the flow rate of inactive gas, and the gas control valve <NUM> is mounted in the internal space P1 of the explosion-proof housing <NUM> and on the wall surface of the explosion-proof housing <NUM> opposite to the gas supply coupling <NUM> across the nozzle head <NUM>.

With this structure, inactive gas introduced from the gas supplier (gas supply coupling <NUM>) can be circulated in the internal space P1. Therefore, it is possible to prevent fresh inactive gas (with relatively lower temperature than the internal space P1) from being immediately exhausted to the outside. Therefore, inactive gas can be effectively used to lower the temperature of the nozzle head <NUM> and the nozzle head <NUM> can be better cooled.

In addition, in the present embodiment, it is provided with a controller (valve control portion <NUM>) that controls the operation of the gas control valve <NUM> and controls the flow rate of the inactive gas exhausted from the gas control valve <NUM> so that the internal pressure of the internal space P1 is higher than the pressure of the external atmosphere.

With this structure, the internal pressure of the internal space P1 can be higher than the external atmosphere, thereby better preventing the external atmosphere from flowing into the internal space P1. Thereby, the explosion-proof performance of the explosion-proof housing <NUM> can be further improved by increasing the internal pressure of the internal space P1.

Although one embodiment of the present disclosure has been described above, various modifications can be made to the present disclosure except for the above embodiment. An example thereof will be described hereinafter.

In the above-mentioned embodiment, the heat-release plate <NUM> has been described as the heat-release unit. However, the heat-release unit is not limited to the heat-release plate <NUM>. For example, a cooling fan which forces inactive gas to flow, a water cooling mechanism which cools the nozzle head <NUM> with cold water and a Peltier element or the like may constitute the heat-release unit in place of or together with the heat-release plate <NUM>.

In addition, in the above-mentioned embodiment, the internal pressure of the internal space P1 is made higher than the external atmosphere by adjusting the flow rate of the inactive gas exhausted from the gas control valve <NUM>. However, the internal pressure of the internal space P1 may be controlled so as to be higher than the external atmosphere by controlling the operation of the pressurizer <NUM> with the pressurizer control portion <NUM>.

In addition, in the above-mentioned embodiment, the temperature sensor <NUM> is mounted to the heat-release plate <NUM> corresponding to the heat-release unit. However, the temperature sensor <NUM> may also be mounted to the nozzle head <NUM> other than the heat-release plate <NUM> and a member fixed to the nozzle head <NUM>.

Claim 1:
A painting robot (<NUM>) configured to discharge paint from nozzles (<NUM>) towards a painting object to perform painting, the painting robot (<NUM>) comprising:
a nozzle head (<NUM>) comprising a plurality of the nozzles (<NUM>) and discharging the paint from the nozzles (<NUM>) by a driving of a piezoelectric substrate (<NUM>);
a power supplier (<NUM>) for supplying power for driving the piezoelectric substrate (<NUM>); and
a robot arm (R1) with a front end to which the nozzle head (<NUM>) can be mounted and moving the mounted nozzle head (<NUM>),
wherein the nozzle head (<NUM>) is provided, in a state in which a nozzle discharging surface (<NUM>) is exposed to the outside, within an explosion-proof housing (<NUM>) that covers portions other than the nozzle discharging surface (<NUM>),
a heat-release unit (<NUM>) releasing heat generated from the nozzle head (<NUM>) is mounted, within the explosion-proof housing (<NUM>), to the nozzle head (<NUM>), and
a temperature measuring unit (<NUM>) measuring a temperature of the heat-release unit (<NUM>) is mounted, within the explosion-proof housing (<NUM>), to the heat-release unit (<NUM>), wherein
the painting robot (<NUM>) is provided with a power cut-off device (<NUM>) which, in response to the temperature measuring unit (<NUM>) detecting that a predetermined temperature has been reached, cuts off a power supply from the power supplier (<NUM>) to the piezoelectric substrate (<NUM>) based on a detection signal from the temperature measuring unit (<NUM>).