JPH0459944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a spray gun for spraying various coating materials such as paint, and particularly to an airless spray gun.

BACKGROUND ART As is well known, airless spray painting is a coating method in which a coating material is fed under pressure using a high-pressure pump such as a plunger pump, and then sprayed from a spray gun equipped with a nozzle tip. This method has the advantage of being able to use a coating material with a higher viscosity than the air spray method, and also has the advantage of high work efficiency as the spray gun discharges a large amount and can coat thickly at one time. For example, in the manufacturing process of automobile bodies, it is used for anti-rust coating on the underside of floors, etc. Vinyl chloride sol, bitumen-based, or wax-based rust preventive materials are used for this type of anti-rust coating, but due to the characteristics of these materials, nozzles are easily clogged by gelled microscopic lumps and foreign matter. In this case, the spray pattern changes, causing inconveniences such as painting areas that are far away from the targeted area.

On the other hand, even in airless spray painting, the coating material scatters, so the working environment is not necessarily good, and when painting the back of the floor, there are problems such as being forced to work in an awkward posture, so it is difficult to use the normal painting process. As in Japan, many industrial robots are being introduced. Industrial robots repeatedly perform operations that have been memorized through teaching operations that have been performed in advance, but they cannot detect or correct nozzle clogging. Conventionally, when this occurs, the following steps were taken:

In other words, since vibrations occur in the nozzle due to the spraying of the coating material, the vibrations can be suppressed by, for example,
As shown in Publication No. 54821, when nozzle clogging occurs, the vibration changes when detected by a sensor such as a microphone, and the nozzle clogging is detected as an electrical signal accompanying the change in vibration. Notify by buzzer or lamp. Maintenance personnel who learned of the nozzle clogging in this way temporarily stopped the line, went to the spray gun where the nozzle was clogged, turned the nozzle tip 180 degrees by operating a lever, and applied the coating material against the nozzle tip for about 1 second. Reverse injection was performed to clear the nozzle blockage, and the line was then restarted.

Problems to be Solved by the Invention However, in the past, although nozzle clogging can be detected automatically, cleaning work to clear the nozzle clogging must be performed manually, which prevents nozzle clogging from occurring. Each time, the entire line or equipment had to be stopped for a long period of time, which not only lowered the operating rate but also became an obstacle to streamlining efforts.

This invention was made in view of the above circumstances, and an object of the present invention is to provide a spray gun equipped with a self-cleaning function that can automatically and quickly perform all operations from detecting clogged nozzles to cleaning them. It is something to do.

Means for Solving the Problems In order to achieve the above object, the present invention provides a nozzle tip having a coating material flow path formed therethrough.
In a spray gun held in a gun body so as to rotate around an axis provided in a direction perpendicular to the axis of the coating material flow path, nozzle clogging is detected based on vibrations accompanying spraying of the coating material. The present invention is characterized in that a sensor is attached to a predetermined location on the gun body, and a step motor that rotates in forward and reverse directions based on the output signal of the sensor is connected to the shaft.

Function: Normal spraying of the coating material is performed by rotating the nozzle tip in the forward direction using a step motor. As a result of spraying the coating material, if the coating material flow path of the nozzle tip becomes clogged with foreign matter, the vibration generated in the nozzle body changes due to a decrease in the amount of spray, and the output signal of the sensor that detects the vibration change changes. Based on this, a step signal is input to the step motor to cause it to rotate in the reverse direction. As a result, the nozzle tip is reversed by almost 180 degrees, and the coating material flow path is in the opposite direction. If the coating material is injected in this state, the coating material will flow from the opposite direction to the coating material flow path, and foreign objects such as foreign matter will be removed from the nozzle. The substances that cause the blockage are removed. Thereafter, the tip motor rotates in the opposite direction, and the nozzle tip is returned to its original normal rotation state.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention configured to be attached to an industrial robot, in which a gun body 1 is fixed to a support 2 having a U-shaped cross section with a set bolt 3; Reference numeral 2 denotes a main body of the gun needle actuator (not shown) which moves the needle 4 back and forth to eject and stop the application material.
It also serves as a member for holding the set bolt 3.
The needle 4 also serves as a needle sleeve for holding and guiding the needle 4, and the needle 4 is inserted into the gun body 1 from the gun needle actuating section body located rearwardly from the gun body 1 through the set bolt 3. A washer 5 is inserted between the set bolt 3 and the support 2, and an O-ring 6 for sealing is inserted between the tip of the set bolt 3 and the gun body 1. The tip of the O-ring 6 is hollow with a diameter larger than that of the needle 4, and the tip of the needle 4 opens and closes the flow path by coming into contact with and separating from a valve seat 7 formed at the tip of the hollow portion. Then, the spraying of the coating material is stopped. Further, a coating material inflow hole 8 is formed to communicate with the hollow portion in the radial direction thereof, and the coating material inflow hole 8 is connected through a union joint 10 screwed into the gun body 1 with an O-ring 9 interposed therebetween. A coating material hose (not shown) is connected to. Further, at the tip of the gun body 1, a roughly spherical nozzle tip 12 having a tapered coating material channel 11 formed therethrough is held by a nozzle cap 13. The nozzle tip 12
As shown in FIG. 1, the state in which the coating material flow path 11 is tapered is the normal rotation state, and the state in which the coating material flow path 11 is tapered is the normal rotation state, and the rotation is centered on the axis along the direction perpendicular to the axis of the coating material flow path 11. A shaft 14, which is the center of rotation, is provided protruding from the nozzle tip 12, and the shaft 14 is sealed to the nozzle cap 13 by an O-ring 15, and protrudes from the nozzle cap 13. Furthermore, a step motor 16 is screwed into the outer surface of the nozzle cap 13 at the point where the shaft 14 protrudes, with a washer 17 and an O-ring 18 interposed therebetween. 14 are directly connected. Step motor 16
As is well known, it is configured to rotate by a predetermined angle for each pulse signal (step signal), and is connected via a lead wire 19 to a control device (not shown) that includes a predetermined drive circuit that outputs the pulse signal. connected.

A microphone 20 serving as a sensor for detecting nozzle clogging is fixed at a predetermined location, for example, on the side surface of the gun body 1, and the microphone 20 processes electrical signals based on the picked-up vibrations to detect nozzle clogging. It is connected via a lead wire 21 to a control device that makes a determination.

Next, the operation of the spray gun configured as described above will be explained.

For normal coating work, the step motor 16
By rotating the nozzle tip 12 in the normal rotation state, the nozzle tip 12 is maintained in the normal rotation state. FIG. 1 shows the normal rotation state, and the nozzle tip 12 is set so that the coating material flow path 11 has a smaller diameter on the tip side. In this state, if the flow path is opened and closed with the needle 4, the union joint 10 A coating material such as vinyl chloride sol, which is force-fed through the coating material inflow hole 8, is injected from the nozzle tip 12. The vibration (sound waveform) in this normal state is stored in the control device.

When a nozzle is clogged due to, for example, foreign matter clogging the coating material flow path 11 of the nozzle tip 12 due to spraying of coating material, the vibration changes as the spray amount decreases, and the microphone 20 detects this and outputs the detection signal. By comparing the normal signal stored in advance, it is determined that the nozzle is clogged, and an abnormality signal is output. Based on this abnormality signal, a pulse signal is output from the control device to the step motor 16, and the rotation of the step motor 16 is stopped with the nozzle tip 12 reversed approximately 180 degrees. Figure 2 shows the inverted state, and in this inverted state,
The coating material flow path 11 of the nozzle tip 12 is oriented in the reverse direction, and the application material flow path 11 of the nozzle tip 12 is rotated in the reverse direction for a predetermined short period of time (for example, about 1 second).
The needle 4 moves back to open the flow path, and the small amount of coating material that is sprayed during that time exerts a force to push out foreign matter in the coating material flow channel 11 in the opposite direction to the previous one, causing the foreign matter to be blown away to the outside. This will clear the nozzle clogging. Note that such a so-called backwash time can be set using a timer.

After the nozzle clogging is cleared in the above manner, a pulse signal is input from the control device to the step motor 16 to rotate it in the opposite direction to that in the above case, and the nozzle tip 12 rotates approximately 180 degrees as shown in FIG. The step motor 16 stops when it returns to the original normal rotation state shown in FIG. Thereafter, normal coating work is performed.

In the above embodiment, a microphone is used as a sensor for detecting nozzle clogging, but in the present invention, a vibration velocimeter or a vibration accelerometer can also be used as a sensor in addition to the microphone. Furthermore, the step motor does not need to be directly connected to the shaft of the nozzle tip, and an appropriate link mechanism may be interposed between the two. In that case, the step motor may be installed at a location other than the side of the gun body. It can be placed at an appropriate location.

Effects of the Invention As is clear from the above description, in the spray gun of the present invention, the nozzle tip through which the coating material flow path is formed is oriented in a direction perpendicular to the axis of the coating material flow path. In a spray gun held in a gun body so as to rotate around a shaft, a sensor for detecting nozzle clogging based on vibrations accompanying spraying of coating material is attached to a predetermined location on the gun body, and Since a step motor that rotates forward and backward based on the output signal of the sensor is connected, the sensor detects nozzle clogging, the step motor reverses the nozzle tip accordingly, and after the nozzle clogging is cleared, the step starts again. The nozzle tip can be rotated back to normal rotation using the motor. Therefore, according to the present invention, all operations from detecting nozzle clogging to clearing can be automated, and the operation can be performed in a short time. As a result, it is possible to obtain excellent practical effects such as increasing the operating rate of the line and improving productivity. Furthermore, since the present invention uses a step motor, the responsiveness of the step motor is good, so that the nozzle clogging can be quickly cleared, that is, the cleaning operation can be performed, and the configuration of the control system can be simplified.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing an embodiment of the present invention, in which FIG. 1 shows the nozzle tip in the forward rotation state, and FIG. 2 shows the nozzle tip in the reversed state. . 1...Gun body, 11...Applying material flow path, 12...
...Nozzle chip, 14...axis, 16...step motor, 20...microphone.

Claims (1)

[Scope of Claims] 1. A nozzle tip through which a coating material flow path is formed is held in a gun body so as to rotate around an axis provided in a direction orthogonal to the axis of the coating material flow path. In this spray gun, a sensor that detects nozzle clogging based on vibrations caused by spraying the coating material is attached to a predetermined location on the gun body, and the shaft is configured to rotate in forward and reverse directions based on the output signal of the sensor. A spray gun with a self-cleaning function that is connected to a step motor.