JPS6223608B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an electrostatic coating device that coats objects to be coated conveyed to a conveyor in a coating booth while moving a coating machine up and down using a reciprocator. The present invention relates to an electrostatic coating device suitable for use when an object has a non-rectangular or non-rectangular parallelepiped painted surface whose area in the height direction is not uniform.

For example, when painting objects suspended from a conveyor in a circular painting booth using an electrostatic atomizer such as a disk type or bell type, the paint film is In order to equalize the
Conventionally, a method has been generally used in which the coating machine is supported by a reciprocator and the coating is carried out while moving the coating machine up and down.

However, with such conventional electrostatic coating equipment, it is possible to apply a uniform coating film to a rectangular or rectangular object that has a uniform coating area in the height direction. but,
It has been difficult to apply a uniform coating to a non-rectangular or non-rectangular object to be coated, where the coating area in the height direction is not uniform. For this purpose, multiple coatings were applied to areas with large painting areas, but in order to automatically perform such multiple coatings, a large number of limit switches were installed within the stroke range of the reciprocator, and the limit switches were activated. The reciprocator was to be reversed in the operating position. This method has the disadvantage that as the shape of the object to be coated becomes more complex, a large number of limit switches are required, and the positioning of each limit switch and the connection of the reciprocator to the drive device become extremely complicated. Ta. In addition, when objects with different shapes are transported to the same painting line, the overcoating range must be changed appropriately depending on the shape of each object, and this requires changing the arrangement of each limit switch. The drawback was that it required a tedious task. Moreover, since the painting line must be stopped while the above-mentioned work is being carried out, there is also the drawback that the painting efficiency is poor.

The present invention improves the drawbacks of the prior art as described above, and its feature is that the drive speed of the paint sprayer by the reciprocator is made variable so that coating can be done according to the shape of the object to be coated. An object of the present invention is to provide an electrostatic coating device in which the speed of the machine can be changed as appropriate.

Embodiments of the present invention will be described below based on the drawings.

First, in Fig. 1, reference numeral 1 denotes a coating machine that electrostatically atomizes paint and sprays it toward the object to be coated;
is supported by a reciprocator 2 so as to be movable up and down. Inside the reciprocator 2 is a lifting mechanism 3 for lifting and lowering the coating machine 1, and a sprocket 3A of the lifting mechanism 3, for example,
An AC motor 5 such as a phase induction motor is provided.

The reciprocator 2 is further equipped with an encoder 6, which transmits a pulse signal every predetermined displacement amount of the lifting mechanism 3, and the pulse signal from the encoder 6 is sent to a height calculation device 7.
is input. The height calculation device 7 calculates the height of the paint sprayer 1 from the reference position by inputting the pulse signal from the encoder 6. A detection device is configured. An absolute position calibration circuit 8 is attached to the height calculation device 7. The absolute position calibration circuit 8 constantly compares the signal output from the height calculation device 7 with its absolute position to prevent errors from being added to the input signal from the encoder 6 to the height calculation device 7. It is intended to prevent The height position signal of the paint sprayer 1 calculated by the height calculation device 7 is input to the comparison calculation device 9. A speed setting mechanism 10 is attached to the comparison calculation device 9, and the speed setting mechanism 10 sets a predetermined height position from the reference position and the driving speed of the reciprocator 2 at that position according to the shape of the object to be coated. This is to set.
The comparison calculation device 9 compares and calculates the height signal inputted from the height calculation device 7 and the height signal set in the speed setting mechanism 10, and calculates the height signal set when the sprayer 1 reaches a predetermined height position. The comparison calculation device 9 and the speed setting mechanism 10 constitute a speed control device.

A variable frequency inverter 11 is connected to the comparison calculation device 9, and the frequency variable inverter 11 changes the rotation speed of the electric motor 5 based on the speed control signal at each height position from the comparison calculation device 9. The device is configured to perform frequency conversion.

The electrostatic coating device having the above-mentioned configuration is
As shown in FIG. 2, the hanger 1 is placed on the conveyor 12.
A workpiece 1 to be coated is suspended by 3 and 13 and transported in a circular painting booth (not shown) in the direction of the arrow in the figure.
4 is to be painted.

Therefore, a case where the electrostatic coating apparatus according to the present invention is used to coat the object 14 having the shape illustrated in FIG. 2 will be described.

The object to be coated 14 has a maximum height H ₀ (H ₀ = H ₁ + H ₂ + H ₃ )
and has a maximum width W ₀ (W ₀ =W ₁ +W ₂ +W ₃ ). Of the total height H ₀ of the object to be coated 14, a portion H ₁ has a painted surface with a width W ₂ , a portion with a height H ₂ has a width W ₀ , and a height H Part ₃ again has a painted surface with a width of W ₂ .

Therefore, when painting the object to be coated 14 having the shape described above, the height position of the coating machine 1 and the driving speed of the reciprocator 2 are set in the speed setting mechanism 10 as shown in the diagram in FIG. Just set it. That is, when the total stroke of the reciprocator 2 is l ₀ ,
The speed in the stroke range l ₁ when the coating machine 1 faces the part of the workpiece 14 at the height H ₁ is v ₁
Let v 2 be _the speed in stroke range l ₂ when facing a part of height H ₂ , and v ₃ be the speed in stroke range l ₃ when facing a part of height H ₃ . , the respective speeds v ₁ , v ₂ ,
v ₃ is the coating area of the object 14 H ₁ ×W ₂ , H ₂ ×W ₀ , H ₃
Set it so that it is inversely proportional to ×W ₂ . In addition, the face-to-face time with the coating machine 1 at each of the above-mentioned parts is
Assuming t ₁ , t ₂ , t ₃ , H ₁ ×W ₂ :H ₂ ×W ₀ :H ₃ ×W ₂ =1/v ₁ :1/v ₂ :1/v ₃ =t ₁ /l ₁ : The driving speed of the coating machine 1 by the reciprocator 2 is determined so as to satisfy t ₂ /l ₂ :t ₃ /l ₃ . On the other hand, when the coating machine 1 is raised to the upper limit position, it is reversed by a reversing mechanism (not shown) and lowered. At this time, the respective speeds v ₄ at the strokes l ₃ , l ₂ , l ₁ ,
v ₅ and v ₆ are the same as v ₃ , v ₂ , and v ₁ , respectively.

Therefore, the coating machine 1 determined as described above
The height positions and drive speeds of the paint are preset in the speed setting mechanism 10, and when the object to be coated 14 is transported into the coating booth, paint is supplied to the coating machine 1 and a high voltage is applied. Then start painting. At the same time, the electric motor 5 is activated to drive the lifting mechanism 3, thereby raising and lowering the coating machine 1. At this time, the height position of the coating machine 1 is detected by the height calculating device 7 based on a pulse signal transmitted from the encoder 6. The height position signal from the height calculation device 7 is input to the comparison calculation device 9, and according to this height position signal, a speed control signal at each height position of the paint sprayer 1 is set in advance in the speed setting mechanism 10. is output from the comparator 9, and the speed control signal is input to the variable frequency inverter 11. The frequency variable inverter 11 converts the commercial power supply frequency into a frequency according to the speed signal and inputs it to the electric motor 5, so that the rotation speed of the electric motor 5 is changed as appropriate.
The moving speed of the coating machine 1 is controlled.

Then, the coating machine 1 selects the coating surface H ₁ × of the object 14 to be coated.
Since the painting area is small while facing the part W ₂ , reciprocator 2 is driven at high speed v ₁ ,
Move the coating machine 1 quickly. On the other hand, coating machine 1
When facing the painted surface H ₂ ×W ₀ , the painting area increases, so the rotation speed of the electric motor 5 is reduced and the reciprocator 2 is driven at a low speed v ₂ ,
Slow down the moving speed of paint machine 1. Furthermore, since the coating area decreases again when the coating machine 1 faces a portion of the coating surface H ₃ ×W ₂ , the speed of the reciprocator 2 is increased by increasing the rotation speed of the electric motor 5 via the variable frequency inverter 11. Increase speed to v ₃ and move paint machine 1 at high speed.

By changing the moving speed of the coating machine 1 as described above, even if the amount of paint supplied from the coating machine 1 is constant, a uniform coating can be formed on all the coating parts of the object to be coated 14.

Note that the electrostatic coating device is capable of coating not only the surface of the object to be coated 14 facing the coating machine 1, but also a small amount of coating in the depth direction at the same time, so that the stroke l ₁ of the reciprocator 2, If l ₂ and l ₃ are set to be slightly larger than the respective heights H ₁ , H ₂ , and H ₃ of the object 14, coating can be performed more efficiently. Further, the ascending speed and descending speed of the coating machine 1 do not need to be the same, and it is sufficient that the speed changes as described above occur during one stroke. Furthermore, a speed change that satisfies the above-mentioned formula may be applied while the sprayer 1 reciprocates several times. Furthermore, when painting the object 14 while rotating in the painting booth, the area to be painted may be calculated over its entire circumference, and based on this, a speed change that satisfies the above-mentioned formula may be set. Furthermore, although the encoder 6 is of a digital type that transmits an incremental or absolute pulse signal proportional to the moving distance of the paint sprayer 1, it can be output as an analog signal using a potentiometer or the like, and then output to a height calculation device. It may be of an analog type that detects the height position of the paint sprayer 1 using 7.

As described in detail above, the electrostatic coating apparatus according to the present invention has a configuration in which the driving speed of the reciprocator can be varied depending on the height position of the coating machine using the variable frequency inverter and the AC motor. The moving speed of the coating machine is changed according to the shape of the object to be coated, and the coating machine is moved at high speed in areas where the area to be coated is small in the height direction of the object to be coated.
By moving at a low speed in areas where the area to be painted is large, it is possible to form a uniform coating film on the object even if the shape of the object is not the same and the area to be painted in the height direction is not the same. It is possible to improve the coating quality. Moreover, since the height position of the sprayer is detected and the speed of the reciprocator is changed accordingly, the height position of the object to be coated and the speed of the reciprocator at that height position can be set in advance. The above-mentioned effects can be obtained by simply setting the speed, and the speed can be set and changed extremely easily and quickly depending on the shape of the object to be coated. Furthermore, by storing setting values regarding a plurality of shapes using a microcomputer or the like, objects of different shapes can be coated continuously.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an electrostatic coating device according to the present invention,
FIG. 2 is an external view showing an example of the shape of an object to be coated by the coating apparatus shown in FIG. 1, and FIG. 3 is a diagram showing the relationship between each height position of the coating machine and the moving speed. 1... Painter, 2... Reciprocator, 5...
Electric motor, 6... Encoder, 7... Height calculation device, 9... Comparison calculation device, 10... Speed setting mechanism, 11... Frequency variable inverter.

Claims (1)

[Claims] 1. In an electrostatic coating device that includes a coating machine that is installed in a coating booth and sprays paint toward an object to be coated, and a reciprocator that moves the coating machine up and down,
an AC motor that drives the reciprocator; a height detection device that detects the height position of the paint sprayer;
a speed control device that outputs a speed signal by comparing the signal from the height detection device with the speed at each preset height position; and a speed control device that outputs a speed signal by comparing the signal from the height detection device with the speed at each preset height position, and the rotation speed of the AC motor is varied by the signal from the speed control device. An electrostatic coating device comprising: a variable frequency inverter; and a variable frequency inverter.