JPS6136990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial painting robot, which automatically adjusts the amount of paint applied to the robot body in accordance with the conveyance speed when the conveyance speed of a conveyance device that conveys the object to be coated changes. It is an object of the present invention to provide an industrial coating robot which has a variable configuration and can thereby reliably prevent coating unevenness caused by fluctuations in conveyance speed.

For example, industrial painting robots are often used when objects to be painted with the same painting pattern are to be painted in assembly line operations. It is transported and automatically painted in a predetermined pattern by a painting robot.

In addition, a typical type of industrial painting robot is the playback type, in which the operator teaches the painting work by moving the robot itself during teaching, and the movements are stored in a memory device. The robot is configured to be memorized and operate the robot according to the memorized information during playback. Therefore, an excellent effect is exhibited when the same coating pattern is applied repeatedly to the object to be coated.

Therefore, even if the coating pattern is the same, if the conveying speed of the conveying device is increased and the operating speed of the robot body is increased to shorten the painting time, the amount of paint applied per unit area of the object to be coated will decrease. The amount of paint becomes smaller, and the thickness of the paint film becomes thinner. The operating speed of the robot body is normally synchronized with the conveyance speed of the object to be coated, so if the conveyance speed during playback is higher than during teaching, or if the conveyance speed fluctuates due to the influence of load during playback, In the case of a coating robot that cannot change the amount of paint applied, the desired thickness of the coating film may not be obtained or uneven coating may occur.

However, in conventional industrial painting robots, when it is desired to vary the amount of paint supplied to the robot body, the operator must, for example, directly change the aperture opening of the spray gun on the robot body, or supply the paint to the paint reservoir. It is necessary to change the pressure of the air for pumping the paint by operating a manual valve, which makes the operation very troublesome, and it has drawbacks such as the inability to accurately control the thickness of the paint film.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings. 1st
Fig. 2 is a schematic diagram of an embodiment of the industrial painting robot of the present invention, Fig. 2 is a circuit diagram of an embodiment of its paint control means, and Fig. 3 is a signal diagram for explaining the operation of the paint control means. A waveform diagram is shown.

In this embodiment, the industrial painting robot 1 shown in FIG. 1 is of the playback type, and can repeat the painting operation taught by the operator during teaching during playback. The robot body 2 has a hydraulically driven arm 3, and a spray gun 4 is attached to the tip of the arm 3 so as to be swingable. Paint stored in a paint reservoir 5 is supplied under pressure to the spray gun 4 via a paint feed pipe 6. The paint supplied to the spray gun 4 is atomized by the atomizing pressurized air supplied through the air pipe 7 and applied to the object 8 to be coated.

The object to be painted 8 is conveyed by, for example, a chain conveyor 9 and passes through the painting place at a constant speed.
In order to make teaching easier, the conveyance speed during teaching is made sufficiently lower than the conveyance speed during playback.

During teaching, when the object to be painted 8 is transported to the painting place, the worker performs a predetermined painting operation on the object to be painted 8 while operating the spray gun 4 with his or her own hand. At this time, the movements of the arm 3 of the robot body 2 and the spray gun 4 are detected by the potentiometer 10, and the movements of each movable part are
It is converted into a digital signal by the D converter 11 and stored in the sequential storage device 12. Further, the movement of the object 8 to be painted is determined by counting pulse signals from a speed pulse transmitter 13 attached to the conveyor 9 from the time when the object 8 closes the switch 14 installed at the entrance of the coating area. detected. The storage device 12 stores the movement of the robot body 2 in synchronization with the pulse signal according to commands from the control device 15, so even if the conveyance speed of the conveyor 9 changes during playback, which will be described later, the object to be coated 8 and the robot body 2
There is no difference in operation between the two.

During playback, when the workpiece 8 carried by the conveyor 9 passes through the switch 14 and the switch 14 is closed, the control device 15 is activated and the operation stored in the storage device 12 causes a speed pulse to be generated. It is read out in synchronization with the pulse signal from the device 13.
The signal thus read out is converted into an analog signal by the D/A converter 16 and then compared with the feedback signal from the potentiometer 10. The deviation of the feedback signal with respect to the analog signal is amplified by the servo amplifier 17 and supplied as a command signal to the drive section 18. Based on the command signal, the drive unit 18 operates the hydraulic source 19.
Hydraulic oil at a predetermined pressure is supplied to the robot body 2 to drive it.

As a result, the robot main body 2 applies a predetermined coating to the object to be coated 8 by operating as taught during the teaching.

Reference numeral 20 denotes a paint control means constituting the main part of the present invention, which is composed of a valve section variable control section 21 and a control section control means 22.

In the case of this embodiment, the valve section 21 includes three electromagnetic on-off valves 21 ₁ , 21 ₂ , 21 ₃ arranged in parallel with each other in a paint delivery pipe 6 that connects the paint reservoir 5 and the robot body 2. It is configured as follows. Each on-off valve 21 ₁ ,
The valve capacities of 21 ₂ and 21 ₃ are _{as follows} :
In this _embodiment , one on-off valve is selectively opened by a signal from the control unit 22.

The control unit 22 is supplied with a speed pulse signal from the speed pulse transmitter 13, and operates three on-off valves 21 ₁ , 21 ₂ , 21 ₃ according to the magnitude of this speed pulse signal, that is, the conveyance speed of the object 8 to be coated. One of the on-off valves is selectively opened and controlled so that the coating concentration of the paint on the object 8 to be painted does not fluctuate.

As shown in FIG. 2, this control section 22 is connected to a frequency-current converter 23, voltage comparators 24, 25, inverter circuits 26, 27, an AND circuit 28, and the on-off valves ₂₁₁ , ₂₁₂ , _213, respectively. It is composed of connected valve drive circuits 29, 30, 31, etc. Frequency-current converter 23 is pulse generator 13
The pulse signal from the converter is converted into a current signal and supplied to each voltage comparator 24, 25. Here, the set voltages V ₁ and V ₂ that serve as comparison standards for the voltage comparators 24 and 25 can be varied depending on the division ratio of the resistors 24a and 24b and the resistors 25a and 25b, respectively. Also, in each voltage comparator 24, 25, the frequency. The current signal from the current converter 23 is set to a voltage V having a value corresponding to its magnitude, and is compared with the set voltages V ₁ and V ₂ respectively, but if the voltage V is larger than the voltage V ₁ or V ₂ At this time, H (high) level signals are output from the voltage comparators 24 and 25, respectively. In this embodiment, the set voltage _V2 is set to a value larger than the set voltage _V1 .

The valve drive circuit 29 is connected to the voltage comparator 24 via the inverter circuit 26, and the valve drive circuit 1 is directly connected to the voltage comparator 25. The valve drive circuit 30 is connected to the output terminal of the AND circuit 28, and one input terminal of the AND circuit 28 is connected to the voltage comparator 24.
Furthermore, the other input terminal is connected to a voltage comparator 25 via an inverter circuit 27.

Here, when the object to be coated 8 is being conveyed at a relatively low speed, the output current of the frequency-current converter 23 is small. Therefore, the outputs from the voltage comparators 24 and 25 are both at L (low) level, and only the valve drive circuit 29 is operated by the output from the inverter circuit 26. As a result, the on-off valve ₂₁₁ with the smallest valve capacity is opened, and a small amount of paint is applied from the spray gun 4.

When the conveyance speed of the object 8 to be coated is medium, the voltage V corresponding to the output current from the arm 3 is the voltage V ₁
and V ₂ . As a result, voltage comparator 2
The output of voltage comparator 24 changes from L level to H level while the output of voltage comparator 24 remains at L level. the result,
The valve drive circuit 29 becomes inactive, and the valve drive circuit 30
only is activated by the signal from AND circuit 28. As a result, on-off valve 21 ₁ closes, and on-off valve 2
Since valves 1 _{and 2} are opened, a medium flow rate of paint is applied from the spray gun 4.

Furthermore, when the conveyance speed of the object 8 to be coated becomes high, the voltage V corresponding to the output of the frequency-current converter 23 becomes larger than the voltage _V2 . As a result, the output of the voltage comparator 25 changes from L level to H level. Therefore, the AND circuit 28 is closed, so the valve drive circuit 30 becomes inactive and only the valve drive circuit 31 operates. Therefore, the on-off valve ₂₁₂ is closed and the on-off valve ₂₁₃ is opened, so that a large amount of paint is applied from the spray gun 4.

In this way, the paint control means 20 controls the object 8 to be painted.
Open/close valves 21 ₁ , 21 ₂ , 21 according to the conveyance speed of
₃ can be selectively operated to prevent uneven thickness of the paint film applied to the object 8 to be coated due to changes in the conveyance speed.

Therefore, even if the conveyance speed of the object to be coated ₈ fluctuates over _time as shown in FIG.
1 _{to 3} are sequentially switched, and it is possible to prevent the paint film from becoming thin or causing uneven coating.

In the above embodiment, the speed pulse signal was supplied to the control section 22 from the speed pulse transmitter 13, but it may be configured to supply the speed pulse signal from another speed pulse transmitter provided separately from the pulse transmitter 13. Good too.

In addition, in the above embodiment, the conveyance speed is divided into three stages and the required amount of paint is applied according to each stage, but the larger the number of floors, the more effectively it is possible to prevent uneven coating. It is.

Further, in the above embodiment, the on-off valve may be configured to open a combination of two or more on-off valves at the same time, in which case the maximum flow rate of the paint that can be fed can be greatly increased, so that the thickness of the paint film can be reduced. It is also possible to increase the range of selection.

Further, in the above embodiment, three on-off valves 21 ₁ , 21 ₂ , 21 ₃ are provided in the coating sulfur feed pipe 6 and each on-off valve 21 ₁ , 21 ₂ , 21 ₃ is selectively controlled to open and close. As in the case of an industrial painting robot 41 shown in FIG. A configuration may be adopted in which control is performed according to the size. In that case, the control valve 42 can also be integrated inside the spray gun 4, for example.

Further, in each of the above embodiments, the painting industrial robots 1 and 41 have been described as being of the playback type, but are not limited to this, and may be of a sequence type using a pin board or the like.

Further, the robot main body 2 is not limited to a hydraulically driven type, but may be an electric type or a pneumatic type.

As mentioned above, the industrial painting robot of the present invention is configured to variably control the flow rate of the paint applied from the robot body according to the conveyance speed of the object to be coated. Even if the operating speed of the robot body becomes faster or slower, such as when the conveyance speed fluctuates due to the influence of load, the control means drives the variable control section to always deliver the required amount of paint. This makes it possible to control the amount of paint applied per unit area of the object to be coated, that is, the thickness of the coating film, to a desired value regardless of the conveyance speed of the conveyance device. It has the following features.

Furthermore, the variable control section is configured to provide a plurality of on-off valves with different valve capacities in the paint supply piping, and to selectively open a predetermined on-off valve in response to a speed signal from a speed detector. By this, when the operating speed of the robot body changes depending on the conveyance speed of the object to be coated, the on-off valve with an appropriate valve capacity can be opened to apply the required paint, and the valve can be opened again. Depending on the combination of on-off valves, the coating amount supply can be varied over a wide range from small flow rates to large flow rates.
This has the advantage that the selection range of the thickness of the coating film can be widened.

In addition, the conveyance speed of the object to be coated is detected as a speed pulse signal, this pulse signal is frequency-current converted, and a voltage comparator compares it with a preset voltage to select a predetermined one of the plurality of on-off valves. By configuring the on-off valve to open, it has the advantage of being able to control the flow rate of paint with an extremely simple configuration.

In addition, by installing a single control valve in the paint delivery pipe and controlling the valve opening degree of this control valve using the speed signal from the speed detector, the amount of paint applied can be varied steplessly. Moreover, it has the advantage that the configuration of the device can be easily simplified.

Furthermore, by making the robot body a playback type, the painting operation taught during teaching can be repeated as many times as desired, and the amount of paint applied can be automatically varied according to the conveyance speed of the object to be painted. Therefore, during teaching, it is possible to carry out the teaching operation while transporting the workpiece slowly, and during playback, it is possible to increase the transport speed of the workpiece, and even in that case, the difference in transport speed between teaching and playback is small. It has the advantage of being able to reliably prevent inconveniences caused by uneven coating due to the occurrence of uneven coating.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the industrial painting robot of the present invention, FIG. 2 is a circuit diagram of an embodiment of the paint control means, and FIG. 3 is for explaining the operation of the paint control means. FIG. 4 is a schematic diagram of a modification of the industrial painting robot of the present invention. 1,41...Industrial painting robot, 2...Robot body, 6...Paint delivery pipe, 8...Object to be painted,
9... Chain conveyor, 13... Speed pulse transmitter, 20... Coating concentration control means, 21... Valve section,
21 ₁ , 21 ₂ , 21 ₃ ... Solenoid on-off valve, 22 ...
...Control unit, 23...Frequency-current converter, 24,
25... Voltage comparator, 42... Control valve.

Claims (1)

[Claims] 1. A speed detector that detects the speed of a conveyance device that conveys the object to be coated, and a speed detector that operates in synchronization with the conveyance speed of the object based on a conveyance speed signal output from the speed detector. , a robot body that applies paint to the object to be painted, a variable control unit that varies the amount of paint applied by the robot body, and a control that drives the variable control unit in accordance with a signal from the speed detector. An industrial painting robot characterized by comprising: means. 2. The variable control unit has a plurality of on-off valves with different valve capacities connected to each other in a feed pipe that feeds paint to the robot body, and the control means controls the speed from the speed detector. 2. The industrial painting robot according to claim 1, wherein the industrial painting robot is configured to selectively open a predetermined on-off valve in response to a signal. 3. The speed detector includes a speed pulse transmitter that transmits a pulse signal according to the transport speed of the transport device, and the control means converts the speed pulse signal from the speed pulse transmitter into a current signal. A frequency-current converter is supplied with a current signal from the frequency-current converter, and a voltage corresponding to the current signal is compared with a preset voltage, and a predetermined on-off valve is operated depending on the magnitude of both voltages. 3. The industrial painting robot according to claim 1, further comprising a voltage comparator for selectively opening the valve. 4. The control means has a single control valve in a feed pipe that feeds paint to the robot body,
2. The industrial painting robot according to claim 1, wherein the industrial painting robot is configured to control the opening degree of the control valve in accordance with the speed signal from the speed detector. 5. The robot main body has a so-called playback type structure in which the coating operation taught during teaching is stored and during playback, the coating operation is repeatedly performed according to the operation taught during the teaching. The industrial painting robot according to item 1.