JPS6223609B2 - - 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 coats were applied to parts with large areas to be painted, but in order to automatically perform such multiple coats, it was necessary to apply multiple coats within the stroke range of a reciprocator driven by a hydropneumatic actuator. A limit switch is provided, and the reciprocator is reversed in the operating position of the limit switch. According to this method, as the shape of the object to be coated becomes more complex,
This method requires a large number of limit switches, and has the disadvantage that the positioning of each limit switch, the connection of the reciprocator to the drive device, etc. are extremely complicated.
In addition, a hydraulic reciprocator or pneumatic reciprocator driven by an actuator such as a hydraulic cylinder or a hydraulic pneumatic pump not only requires a hydraulic or pneumatic source such as a hydraulic pump or an air compressor, but also requires a hydraulic or pneumatic source such as a hydraulic pump or an air compressor. A piping system is required to connect the and the hydraulic/pneumatic actuator, which has the disadvantage of complicating the configuration and increasing the size. Furthermore, in an electric reciprocator that is driven by an electric motor, if you try to reverse the reciprocator in the middle of its stroke, the sprayer will suddenly stop, so a reaction force against the inertia of the sprayer will act on the reciprocator, causing the reciprocator to The cage vibrates, causing dust to scatter into the painting atmosphere and adhere to the paint film. For this reason,
In reality, electric reciprocators have only been used with a configuration in which the reciprocator is always reversed over the entire stroke using a unidirectional rotating electric motor and a reversing mechanism provided at the stroke end of the reciprocator.

The present invention improves the drawbacks of the prior art as described above, and is characterized by detecting the height position of the paint sprayer using a height detection device, and based on this detection signal, the paint sprayer can be rotated in forward and reverse directions. An object of the present invention is to provide an electrostatic coating device that uses an AC motor to appropriately change the reversing position of a coating device depending on the shape of an object to be coated.

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 onto an object to be coated.The coating machine 1 is supported by a reciprocator 2 so as to be movable up and down. Inside the reciprocator 2, there is a lifting mechanism 3 for lifting and lowering the coating machine 1, and an alternating current motor 5, such as a three-phase induction motor, which is connected to a sprocket 3A of the lifting mechanism 3 via a speed reducer 4 and can be reversed. It 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 reversal position setting mechanism 10 is attached to the comparison calculation device 9, and the reversal position setting mechanism 10 is preset as a reversal position at a predetermined height position from a reference position according to the shape of the object to be coated. The comparison calculation device 9 calculates the height signal inputted from the height calculation device 7 and the reversal signal set in the reversal position setting mechanism 10, and outputs the reversal signal when the reversal position is reached. and the reversal position setting mechanism 10 constitute a reversal control device. A variable frequency inverter 11 equipped with a reversing mechanism is connected to the comparison calculation device 9, and the variable frequency inverter 11 performs inversion while applying a cushioning action to the paint sprayer 1 based on the output signal from the comparison calculation device 9. It is configured to allow That is, when the sprayer 1 approaches the reversal position, it is decelerated and stopped, and after the electric motor 5 starts reversing, the speed is gradually increased.

The electrostatic coating device having the above-mentioned configuration is
As shown in FIG. 2, the hanger 1 of the conveyor 12
3 and 13, and is conveyed in a circular painting booth (not shown) in the direction of the arrow in the figure.

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 , the H ₁ part has a painted surface with a width W ₂ , the painted surface of the height H ₂ part has a width W ₀ , and the height H ₃ part has a width W ₂ again. It has a painted surface.

Therefore, the object to be coated 14 having the above-mentioned shape is
When painting, the inversion position setting mechanism 10 sets the inversion position of the paint sprayer 1 by the reciprocator 2 to the third position.
The settings can be made as shown in the diagram in the figure. That is,
Of the entire stroke of the reciprocator 2, its lower end position is S ₁ , the position corresponding to the height H ₁ of the workpiece 14 is S ₂ , the position corresponding to the height H ₂ is S ₃ and the height
When the position corresponding to H ₃ is S ₄ , the reciprocator 2 is first stroked from S ₁ to S ₄ , reversed, and then stroked from S ₄ to S ₂ .
After that, it is reversed and stroked from S ₂ to S ₄ , and then further reversed and stroked from S ₄ to S ₁ . Then, reverse the reciprocator 2 again.
Stroke from S ₁ to S ₃ , reverse, and from S ₃ to S ₁
stroke until. The operation of the reciprocator 2 as described above is regarded as one cycle, and the reversing position setting mechanism 10 is set in advance to repeat the cycle, and the speed is slow immediately after the start of reversal, and thereafter it proceeds at high speed, until the reciprocator 2 is in the vicinity of the reversing position. It is specified that the speed should be decelerated at , and the speed immediately after the start of reversal should also be slowed down. For example, immediately after the start of inversion it is 25Hz, then it is 50Hz,
Near the reversal position, the electric motor 5
Set the rotation speed.

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 to start coating. At the same time, the reciprocator 2 is driven to raise the coating machine 1 from the position _S1 . At this time, since the drive speed of the electric motor 5 can be made variable by the variable frequency inverter 11, as shown in FIG. operates smoothly and no impact is applied to the reciprocator 2. Then, the displacement of the sprayer 1 is inputted every moment to the height calculation device 7 via the encoder 6, and when the stroke of the reciprocator 2 approaches _S4 , the signal from the comparison calculation device 9 is inputted to the variable frequency inverter 11. Therefore, the electric motor 5 is gradually decelerated by the frequency variable inverter 11, and when the stroke reaches _S4 , the electric motor 5
stops. After that, the variable frequency inverter 11
The electric motor 5 is reversed by the reversing mechanism provided in the motor 5, and the speed is gradually increased. As a result, the coating machine 1 starts descending, and when its stroke reaches S ₂ , S ₄ , S ₁ , and S ₃ , the same reversal operation as described above is performed. In this case, when the sprayer 1 is suddenly accelerated or suddenly stopped at its reversed position, a reaction force against the inertial force acting on the sprayer 1 acts on the reciprocator 2, and the reciprocator 2 Although the vibration caused by the impact causes dust and the like to be scattered into the coating atmosphere, as mentioned above, the speed of the sprayer 1 is adjusted near the inversion position, so there is no risk of dust and the like being scattered.

If the reciprocating position of the reciprocator 2 is controlled as described above, the coating machine 1 will spend the time facing the _H2 height part of the workpiece 14 facing the _H1 height part or
The time spent facing the height part of H ₃ will be longer. Therefore, a large amount of paint can be supplied to a part with a large painting area H ₂ ×W ₀ , and a large amount of paint can be supplied to a part with a small painting area H ₁
Since only a small amount of paint is supplied to the parts ×W ₂ and H ₃ ×W ₂ , the coating film is uniform over the entire painting area.

Furthermore, since the absolute position of the paint sprayer 1 is constantly calibrated by the absolute position calibration circuit 8, no error is added to the height calculation device 7 even if the reciprocator 2 repeatedly performs reversal operations. .

Note that the electrostatic coating device is capable of coating not only the surface of the object 14 facing the coating machine 1 but also a small amount of the surface in the depth direction at the same time, so that the stroke range of the reciprocator 2 is covered. If the height of the coating material 14 is set to be slightly larger than H ₀ , more efficient coating can be achieved.
Furthermore, the object to be coated is not limited to the shape shown in FIG. 2, but can also be applied to other shapes in which the coating area in the height direction is not uniform. Then, depending on the shape of the object to be coated, the reversal position and the number of times of reversal may be appropriately set so that the coating film becomes uniform over the entire coating surface. Furthermore, encoder 6
Although this was described as a digital system that transmits an incremental or absolute pulse signal proportional to the moving distance of the paint sprayer 1, for example, it is output as an analog signal using a potentiometer, etc. It may be of an analog type that detects the height position of.

As described in detail above, according to the electrostatic coating apparatus according to the present invention, the height position of the coating machine that is supported by the reciprocator so as to be able to rise and fall is detected by the height position detection device, and the height position of the coating machine that is movably supported by the reciprocator is detected. The reciprocator can be reversed at an appropriate position by rotating the AC motor in the forward or reverse direction via a variable frequency inverter based on the detection signal and the frequency variable inverter. By appropriately setting the reversal position and number of reversals,
It is possible to make the coating film uniform over the entire painted surface. Furthermore, since the height position of the paint sprayer is detected and the electric motor is used to reverse the reciprocator at a predetermined height position, the above-mentioned effects can be achieved simply by setting the reciprocator reversal position in advance. The inversion position can be set and changed very easily and quickly depending on the shape of the object to be coated. Furthermore, since the reciprocator is driven by an AC motor capable of forward and reverse rotation, and the reversal is performed by a variable frequency inverter equipped with a reversing mechanism, the speed of the sprayer when the reciprocator is reversed can be adjusted as desired. be able to. Therefore, it is possible to prevent the inertial force of the sprayer from acting on the reciprocator when the sprayer is stopped or reversed, and the reciprocator can be prevented from vibrating during painting and causing dust etc. to be scattered in the coating atmosphere. can be prevented. Furthermore, since it uses an electric reciprocator driven by an electric motor, there is no need to connect a hydraulic or pneumatic source or piping system to the reciprocator, compared to one that uses a hydraulic or pneumatic actuator. It is possible to simplify the configuration and reduce the size of the device. 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 the object to be coated by the coating device shown in Fig. 1, and Fig. 3 is a line showing the reversal locus of the reciprocator when painting the object to be coated in Fig. 2. It is a diagram. 1... Painter, 2... Reciprocator, 5...
AC motor, 6... Encoder, 7... Height calculation device, 9... Comparison calculation device, 10... Reversing position setting mechanism, 11... Frequency variable inverter.

Claims (1)

[Claims] 1. In an electrostatic coating device consisting of a coating machine installed in a coating booth and spraying paint toward the object to be coated, and a reciprocator that moves the coating machine up and down,
An alternating current motor capable of forward and reverse rotation that drives the reciprocator, a height detection device that detects the height of the coating machine, and a signal from the height detection device that is set in advance according to the shape of the object to be coated. An electrostatic device comprising: a reversing control device that outputs a reversing signal based on a comparison with a reversing position; and a variable frequency inverter equipped with a reversing mechanism that reverses the AC motor based on a signal from the reversing control device. Painting equipment.