JPS6197062A - Paint applicator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a paint application device, and more specifically, the present invention relates to a paint application device, and more specifically, the adhesion of finely divided paint particles to an object to be coated causes the finely divided paint particles to be tinged. It relates to a paint application device of the type that is facilitated by an electric charge.

(Prior Art) 'In the paint manufacturing industry and in the paint industry, the main focus of research has been directed towards reducing environmental pollution for several years now. Many major industrialized countries impose strict emission standards on painting companies regarding the amount of various pollutants released into the atmosphere. A vehicle (vehicle) is a medium in which pigments are dispersed, and is a film-forming element (R material) dissolved in an organic solvent.A vehicle (color vehicle) is a solvent added to adjust the viscosity of the paint to a level suitable for painting. Industrial paint spraying operations that are diluted with certain thinners are a significant source of solvent emissions. When the paint containing the organic pigment dispersed therein is applied to an article and then the paint dries, the organic vehicle and solvent are released from the pigment, which is the solid component of the paint, and evaporate. Special precautions must be taken to maximize the capture of such organic vehicles and solvents. This requires the investment of installing air pollution monitoring equipment to remove the solvents and organic vehicles from the air recovered from the paint spray room.

Recently, devices that charge atomized paint particles during the atomization process have become increasingly popular as a technique for increasing the efficiency of adhesion of paint to an object. This device became popular because it was recognized that the higher the percentage of atomized paint particles that adhered to the object, the less paint was needed. Two advantages are immediately derived from this result. The first advantage is that less paint, which is normally expensive, is used. A second advantage is that because less paint is used, the expected emissions of solvents and organic vehicles are also reduced.

Another method for reducing the amount of organic solvents and vehicles released during factory painting operations is the use of water-based paints. Apart from water, water-based paints contain only a small amount of solvent, e.g. alcohol, so that when such paints are applied and dried, the main component released into the atmosphere is water, and therefore the solvent is released. The problem of being lost is significantly reduced. However, water-based paints are expensive and
Therefore, there is currently a great deal of interest in maintaining the amount of paint that is atomized at the lowest possible level, and thus charging the paint particles during the process of atomization of such water-based paints. There is still a great deal of interest in the high adhesion efficiencies obtained by this method.

A non-negligible problem when applying such water-based paints is that both the vehicle/solvent and the water are highly conductive.

Because paint must be supplied to the atomizer from a source, whenever paint is supplied from a source to an atomizer, there is an electrical path from the atomizer back to the source. Therefore, charging the paint particles during the process of atomization of the paint means that
It is not as simple as attaching a high-voltage power source to an atomizer and activating the power source. This is because whenever paint flows into the atomizer, there is an electrical path from the high-voltage power source back to the paint source, creating a low-resistance electrical path between the terminals of the high-voltage power source. be.

Typically, the high voltage power supplies used to apply such paints are not designed to maintain high voltages across the power supply terminals under high current load conditions for safety reasons.

Therefore, such a high-voltage power supply can be used to maintain an acceptable potential to charge the atomized paint particles with sufficient charge so that the paint moves between the atomizer and the object to be painted with maximum possible efficiency. It is almost impossible to apply the current to the atomizer.

To solve this problem when using water-based paints, the part of the paint applicator that is connected to the atomizer must be isolated from earth potential (ungrounded).

When using only one paint source to spray only one paint color, it is usually feasible to electrically isolate the paint source from earth potential (ungrounding). .

One of the methods used to solve this problem is the so-called “voltage block”.
``)'', which places an intermediate paint sump between the large-capacity paint supply and the paint spray equipment. A bolt block that is intermittently or continuously refilled with paint from a source can maintain its potential at ground potential. The intermediate paint reservoir itself is insulated from earth, and its potential should either be at the same potential as the paint spraying equipment to which it is connected, or at an intermediate potential (between the equipment potential and ground potential). It's normal. Steps should be taken to determine if there is any current flowing from the intermediate paint reservoir back to the high voltage power supply.

Various bolt blocks are known, and related patents include Fortin, U.S. Pat. No. 1.
No. 655.262, Silsbee, Jr.
U.S. Patent No. 2.673.232 to y % Jr), U.S. Patent No. 3.09 to Peterson
No. 8.890, Uline et al.
), U.S. Pat. No. 3,291.889; Van Loo et al., U.S. Pat. No. 3.3.
No. 60,035, U.S. Pat. No. 4,020,866 to Wiggins, Beck et al.
et al., U.S. Pat. No. 3,122,320; Rokadia, U.S. Pat. No. 3,893;
No. 620, Wiggins U.S. Pat. No. 3,933,285, Tamny U.S. Pat. No. 3,934,055, and Spanjersberg et al. U.S. Pat. .275,834.

For example, much more difficult problems arise when attempting to paint with different types of water-based paints, such as different colored paints, such as on an automobile paint line. Isolating a single paint supply from the ground is not particularly technically complex. However, in order to use more than 20 different colors for painting on an automobile painting line, a considerable number of paint applicators are required, and all such equipment must be insulated from the ground. Granted, using several bolt blocks to paint with just one color paint is cheap, easy, and safe, but it's also possible to use multiple bolt blocks for painting with just one color paint, but it's also possible to use multiple bolt blocks for painting with just one color paint, but it's also possible to use multiple bolt blocks for painting with just one color paint. Some of the bolt blocks used are extremely complex, as they are painted with multiple colored paints.

Dalton describes the complexity of multiple bolt block equipment for spraying multiple paints on a paint line.
) are described by way of example in US Pat. No. 4,085,892. The device shown in this patent is a paint applicator that uses only five different color paints, compared to a paint applicator that must spray paint as many colors as is commonly used on an automotive paint line. It's quite simple.

One proposal that has been made to solve the above problem is to use a single bolt block to spray paint multiple colors.

This proposal has proven to be undesirable because, in the very short time it takes to change a paint color on a high-speed paint line, any remaining paint of the original color can be removed. Purge everything from the intermediate paint reservoir,
Filling this reservoir with paint of a new paint color is extremely difficult, if not impossible. In addition, with this type of paint applicator, if a painter tries to change the paint color within a short period of time before moving on to the next object to be painted, the new paint color will inevitably be applied to the previous paint. Will be contaminated by colored paint.

OBJECTS OF THE INVENTION In accordance with the present invention, an apparatus and method for spraying highly conductive paints, such as water-based paints and metal powder paints and paints containing highly conductive vehicles and solvents, is provided. Furthermore, the present invention can be effectively used in recently developed solution-type high solid paints that use solvents that have both extremely high polarity and conductivity. The method and apparatus of the present invention enable high paint color change rates and wide paint color selection ranges, such as those required on automotive paint lines, to be achieved without the need for bolt blocks or similar equipment. be.

(Structure of the Invention) According to the present invention, an apparatus for applying paint to an object of a type in which a potential difference is maintained between an object and paint particles ejected for painting the object is provided. A paint particle ejection device is included to subdivide the paint stream to form particles. The paint application device has a device thereon for coupling the paint particle ejection device to a paint supply source, a partition, and a side of the partition opposite to the side on which the ejection device is located. and a power source for maintaining an electrical potential between the object and the electrode of a sufficiently high amount to create and maintain a potential difference between the subdivided particles of paint and the object.

This configuration results in an electrical repulsion acting between the electrode and the finely divided loose particles of the paint and an attractive force acting between said particles and the object, thus increasing the adhesion efficiency, i.e. , the percentage of paint ejected by the particle ejector that actually contributes to the coating of the object is increased. In order to reduce the possibility of electrical discharge occurring between the paint particle ejector and the electrode, the barrier wall is constructed at least in part of a material having a dielectric strength that is high compared to that of the environment surrounding the paint particle ejector. .

In the illustrated embodiment, the partition wall is made at least in part of a resin material.

According to the illustrated embodiment, a device is provided for maintaining the paint particle ejector at substantially neutral potential, ie, ground potential.

Additionally, according to the illustrated embodiment, the septum is generally cylindrical and surrounds the paint particle ejector. The cylindrical partition is open at one end, from which the paint particle ejection device ejects subdivided paint particles, and at the opposite end, at which the support device supports the paint particle ejection device in an orientation away from the object. In the illustrated embodiment, the electrode includes a device forming a conductive ring extending around the outer surface of the cylindrical septum.

Further, according to the illustrated embodiment, the electrode includes one or more electrically conductive discharge tips extending from the ring generally toward the target.

According to the illustrated embodiment, the most anterior surface or forward end of the ring faces towards the object in a first direction, and the rear end of the ring faces rearwardly in a second opposite direction away from the object. The cylindrical septum has a forward end closer to the object in a first direction than the forward end of the ring, and a rearward end farther from the object than the rear end of the ring in a second direction. The distance from the forward end of the ring to the forward end of the septum is generally equal to the distance from the aft end of the ring to the aft end of the septum.

According to one embodiment, this distance is generally greater than the distance from the front end of the ring to the rear end of the ring.

According to the illustrated embodiment, the paint particle ejection device includes a rotary atomizer and a device for rotating the rotary atomizer at a speed sufficient to generate finely divided paint particles.

Additionally, in accordance with the present invention, the generally cylindrical bulkhead surrounding the rotary atomizer has an axis extending generally parallel to the axis of rotation of the rotary atomizer, and the ring has an axis generally coaxial with the axis of rotation of the rotary atomizer. It is.

As shown, the generally cylindrical septum or sleeve has a generally circular cross section perpendicular to its axis, and the ring has a generally circular cross section perpendicular to the sleeve axis. Additionally, according to the illustrated embodiment, the ring has generally circular (two) faces that are generally parallel to the sleeve axis.

According to the illustrated embodiment, an apparatus for providing additional streams of a number of different paints to a rotary atomizer and selectively controlling which of the different paints flows to the rotary atomizer at a given time. A device is provided.

In the method of applying paint to an object, the paint flow is subdivided to form paint particles, a partition wall is provided, the electrode is on the side of the partition wall, and the paint is finely divided.

Placed on the side opposite to the side to be split, a potential difference is maintained between the object to be painted and the electrode. This potential difference is large enough to create and maintain a potential difference between the finely divided particles of paint and the target, so that there is no electrical connection between the electrode and the finely divided paint particles. There is an anti-tΩ force and an electrical attraction between the subdivided paint particles and the object. According to the method of the present invention, the septum is made of a material having a relatively higher dielectric strength than the environment surrounding the paint ejector to reduce the possibility of electrical discharge occurring between the paint ejector and the electrodes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be better understood upon reference to the following description and accompanying drawings that illustrate embodiments of the invention.

FIG. 1 shows an end view on the exit side of a typical painting chamber for painting the body of an automobile with paint of a selected paint color from among various prepared paint colors.

Three devices 10.12.14 for ejecting atomized paint particles, which may commonly be of the type described in U.S. Pat. No. 4,275,838, spray paint onto the right side 16 of the vehicle body 18. Three devices 20.22.24 primarily share responsibility for spraying the paint onto the left side 26 of the vehicle body 18, and three devices 28.30
．． 32 is primarily responsible for spraying the paint onto the upper portion 34 of the vehicle body 18. The devices 28.30,'32 are normally mounted on reciprocating cylinders 46 such that the devices 28.30.32 can be moved forward or backward relative to the contours of the upper portion 34 of the vehicle body 18. In addition, a device for atomizing paint and ejecting it 10.12.14.20
．． 22, 24, 28, 30, 32, the reciprocating cylinder 36, the hydraulic and pneumatic cylinders attached to these,
Electrical pipes and pipe fittings are housed in an enclosure 40 disposed inside a painting chamber 42 through which a conveyor 44 extends. The enclosure 40 generally has an inlet end where articles to be painted, herein vehicle bodies, enter on a conveyor 44, and an exit end (see FIG. 1) where the painted vehicle bodies exit on a conveyor 44. It is a long tunnel-like chamber with a Spraying device 10.12.14.20.2
2.24.28.30.32 In order to lower the paint that did not adhere to the vehicle body among the finely divided and sprayed paint, it includes a ceiling fan 46, an air filter 47, and a floor grating 48. The equipment allows air to circulate through the painting chamber 42. Excess paint not adhering to the vehicle body is removed by washing it with water through the lower floor grate 48.

Referring to FIG. 2, which shows details of the equipment shown in FIG. A device is shown. The spraying device 10 is attached to one end of the horizontal support member 50, and the other end can be movably mounted, such as by being pivoted within the enclosure 40, so that the spraying device 10 can spray paint onto the vehicle body 18 passing in front of it. It is possible to perform some vertical movement when spraying. The spray device 10 and the horizontal support member 50 are grounded to the ground so that the spray device 10 and the horizontal support member 50 are maintained at ground potential.

The paint applicator of FIG. 2 includes thereon a color paint supply manifold 58, a portion of which is shown in the figure. Color paint supply manifold 58 includes a plurality of pneumatically operated color paint supply valves, six of which are shown, 60-65. These color paint supply valves 60-65 are for controlling the flow of various color paints selected for paint color out of the respective color paint supplies and into the color paint supply manifold. A solvent supply valve 82 is located at the top 84 of the color paint supply manifold 58 . A paint supply conduit 86, also maintained at ground potential, extends from a lowermost portion 88 of the color paint supply manifold 58 to a trigger valve 90 located proximate the spray device 10. A paint supply tube 92 is connected to the outlet port of trigger valve 90. The paint supply tube 92 connects to the color paint supply manifold 5.
The color paint that has flowed into the paint supply line 86 through one color paint supply valve selected from among the eight color paint supply valves 60 to 65 is supplied to the interior of the spraying device 10. The spraying device 10, which rotates at high speed, atomizes the paint of the selected paint color and sprays it out in the form of mist.

For the purpose of cleaning the interior of the spraying device 10 during the color paint changeover cycle that normally occurs following the application of color paint to each car body transported on the conveyor 44, 97 extends from a pressurized solvent source (not shown) through valve 93 and tube 95 to spray device 10. This tube 95 is used to remove any amount of previously used color paint remaining in the spray device 10 from the spray device 10 prior to starting the spraying of the next color paint. This is for supplying water into this spraying device.

The particulate paint ejected by the device 20 is caused, in part, by the electrical forces acting on the particulate paint particles, to the vehicle body being carried on a grounded conveyor. Move towards 18. A high-voltage electric current 1xoo is provided to charge the atomized paint particles and to make the electrical force available. This high voltage power supply 100 is, for example, US Pat. No. 3,8
No. 75,892, U.S. Patent No. 3.851.618, U.S. Patent No. 3.894,272, U.S. Patent No. 4,075
, 677, U.S. Pat. No. 4,187,527, or F.
The application was filed on April 19, 1982 under the name OLD-BACK POWER5UPPLY (foldback power supply).
Wood wrap (Wood wrap) also assigned to the assignee of this application
U.S. Patent Application No. 36Q of 1982 for
It may also be of the type shown in No. 365.

A partition wall 102 in the form of a right cylindrical sleeve is connected to this partition wall 1.
02 is coaxial with the rotation axis of the spraying device 10. It extends from near the surface of the enclosure 40 and almost reaches the front spout end of the spray device IO. The forward and rear ends 106 and 108 of the sleeve 102 are both open to accommodate both the spray device 10 and the horizontal support member 50. A mounting post 111 is provided on the inner wall 110 of the sleeve 102 . The outer wall 112 of the sleeve 102 is smooth and unbroken apart from a plurality of standoffs 114 projecting radially outward therefrom and supporting electrodes 116 in the form of conductive rings. These standoffs 114, at either end of the ring 116, connect the ring 116 to the sleeve 102.
This ring 116, like the previously described sleeve 102, is coaxial with the axis of rotation of the spray device 100 because it is supported at a generally equal distance from the outer wall 112 of the sleeve 102. This ring 11
6 is located at generally the longitudinal center of the sleeve 102, ie, at generally the same distance from the forward and rear ends 106 and 108 of the sleeve. However, a large number of needle electrodes 118 are equidistantly spaced on the front surface of the ring 116.
The needle electrode projects from the front face of the ring 16 towards the front end 106 of the sleeve 102. A high voltage cable 120 connects one terminal of the high voltage power supply 100 to the ring 116 . The other output terminal of the high voltage power supply lO0 is grounded to the ground.

Energization of high voltage power supply 100 causes a continuous electrical discharge from needle electrode 118 and, to a lesser extent, from ring 116 in general. A sleeve 102 made of a material with a relatively higher dielectric strength than the air surrounding the spray device 10 ensures that such electrical discharges
0 and the support member 50 combined with it, or through the grounded paint or the pneumatic supply line attached to the spraying device 10, reducing the possibility that it will flow to the ground. . In the illustrated embodiment, the sleeve 102 is made of some type of resin, a plastic material with an acceptably high dielectric strength.

When the paint applicator is activated and atomized paint particles are ejected from the ejection end 104 of the spray device 10, the paint particles are ejected generally radially outward from the rotation axis of the spray device 10. Due to the presence of the sleeve 12, the atomized paint particles are delayed away from the electric field created and maintained between the ring 16 and in particular the needle electrode 118 and the car body 18. However, once the atomized paint particles have progressed through the sleeve 102 and radially outwardly past its open front end, they are exposed to an electric field and are simultaneously exposed to the ring electrode 116 and, in particular, to the needle. It is exposed to a discharge from electrode 118. This discharge charges the finely divided paint particles.

Once charged by this discharge. Such paint particles are accelerated by both the electrical repulsion that exists between like-sign charged particles and between them and the electrode 116, and the electrical attraction due to the ground potential prevailing in the vehicle body 18.

Due to the slow closing effect of the sleeve 102 having a high dielectric strength, the ring 116 with the needle electrode 118 and the spraying device 10 supported by the support member 50, various paints, and pneumatics attached to the spraying device 10 can be used. The likelihood of electrical discharge occurring between any of the grounded components, such as a fitting, is significantly reduced. Furthermore, due to the delayed closing effect of the sleeve 102 having high dielectric strength,
The smaller dimensions of the ring 16 are made possible because the possibility of electrical discharge occurring between the ring 16 and the device 10 is reduced. This makes it possible to space the spraying devices 10 as shown in FIG. This is often the case when assembling applicator devices. Rings 116 of smaller dimensions can be used so that even if spray devices with such rings are placed very closely spaced, the rings assembled in the spray device can be prevented from colliding with adjacent spray equipment.

Since the spraying device 10 is grounded, the vehicle body 1
It becomes possible to spray paint closer to the surface of the vehicle 8, since there is no risk of spark discharge occurring between the device 10 and the vehicle body 18. Closer spray painting improves the efficiency of paint particle transfer to the vehicle body, and provides greater freedom to control the spray coating pattern to improve coating thickness uniformity and coating quality. degree increases.

[Brief explanation of the drawing]

FIG. 1 is an exit side end view of a painting chamber for an automobile body, and FIG. 2 is an enlarged view showing details of the painting chamber shown in FIG. 1. 10...Blowout device 18...Target 100...Power source

Claims (1)

[Claims] 1. An apparatus for applying paint to an object, in which a potential difference is maintained between the object and paint particles ejected to paint the object, the apparatus forming paint particles. a paint particle ejection device for subdividing the paint stream for the purpose of subdividing the paint stream, a device for coupling the device to a paint supply source, a partition, a side of the partition opposite to the side on which said ejection device is located; the partition wall, including an electrode disposed on the side and a power source for maintaining an electrical potential between the object and the electrode of a sufficiently high amount to maintain a potential difference between the subdivided particles of paint and the object; A paint application device characterized in that it is made of a material having a higher dielectric strength than the dielectric strength of the environment surrounding the spray device. 2. The paint application device according to claim 1, wherein at least a portion of the partition wall is made of a resin material. 3. A paint application device according to claim 1, including a device thereon for maintaining the ejection device at substantially ground potential. 4. A paint application device according to claim 1, including a device in which the partition wall is generally cylindrical in shape and surrounds the ejection device, and the electrodes form a ring extending around the outer surface of the cylinder. 5. A paint application device as claimed in claim 1, wherein the electrode includes a discharge tip thereon extending from the ring generally towards the object. 6. The paint applicator of claim 5, wherein the electrode includes multiple spaced discharge tips extending from the ring generally toward the object. 7. The ring has a forward end in a first direction toward the object and a rearward end in a second and opposite direction, the forward end having the septum closer to the object than the forward end of the ring. in a first direction, and has a rear end in a second direction that is more distant from the subject than the rear end of the ring, and the distance from the front end of the ring to the front end of the septum is equal to or greater than the distance from the rear end of the ring to the septum. The paint applicator according to claim 4, which is equal to the distance to the rear end of the paint applicator. 8. The paint applicator of claim 7, wherein said distance is substantially longer than the distance from the front end of the ring to the rear end of the ring. 9. The electrode includes multiple discharge tips extending from the ring generally toward the target, the ring having a forward end in a first direction toward the target and a rear end in a second, opposite direction; wherein the septum has a forward end closer to the object than a forward end of the ring in a first direction and a rearward end farther from the object than a rearward end of the ring in a second direction; The distance from the front end to the front end of the septum is substantially equal to the distance from the rear end of the ring to the rear end of the septum, and the ejection device is connected to the rotary atomizer with a distance sufficient to generate finely divided paint particles. and a device for rotating the rotary atomizer at a speed, and wherein the device coupling the ejection device to the paint supply source includes a device for supplying a stream of paint particles to the rotary atomizer. Coating device. 10. A device for applying paint to an object in which a potential difference is maintained between the object and the paint particles ejected to paint the object, the device controlling the flow of paint to form paint particles. a device for ejecting paint particles for subdivision, a device for coupling the device to a source of paint, a septum, and an electrode disposed on the side of the septum opposite the side on which said ejector is located; , a power source for maintaining a sufficiently high electrical potential between the object and the electrode to maintain a potential difference between the subdivided particles of paint and the object, and a power source for maintaining the ejection device at substantially neutral potential. What is claimed is: 1. A paint application device comprising a maintenance device, the partition wall being made of a material having a dielectric strength higher than that of an environment surrounding the ejection device. 11. The ejection device includes a rotary atomizer and a device for swirling the rotary atomizer at a velocity sufficient to generate finely divided paint particles, and a device coupling the ejection device to the paint source directs the flow of paint particles. Claim 10 encompasses a device for feeding a rotary atomizer.
Paint applicator as described in Section. 12. The septum includes a generally circular sleeve surrounding the rotary atomizer and a device for pivoting the rotary atomizer, the axis of the sleeve extending generally parallel to the axis of the rotary atomizer, and the electrodes extending outside the sleeve. 12. A paint application device as claimed in claim 11, including the device forming a ring extending around the coating. 13. Claim 1, wherein the electrode includes multiple spaced discharge tips thereon extending from the ring generally toward the object.
The paint application device according to item 2. 14. The ring has a forward end in a first direction toward the object and a rearward end in a second and opposite direction, the forward end having the sleeve closer to the object than the forward end of the ring. in a first direction and having a rear end in a second direction that is more distant from the subject than the rear end of the ring, and a distance from the front end of the ring to the front end of the sleeve, and from the rear end of the ring. Claim 1: The distances to the rear end of the sleeve are substantially equal.
The paint application device according to item 2. 15. A device for applying paint to an object in which a potential difference is maintained between the object and paint particles ejected to paint the object, the paint application device being a rotary atomizer, the rotary atomizer a generally cylindrical sleeve surrounding the rotary atomizer with the swirling device; a ring-shaped member having an axis extending generally parallel to the axis of rotation of the rotary atomizer and surrounding the sleeve and disposed at a generally equal distance from the end of the sleeve through which the atomizer projects and the end of the sleeve opposite the end of the sleeve; electrodes, a power supply that maintains a sufficiently high amount of electrical potential between the electrodes and the object to maintain a potential difference between the subdivided particles of paint and the object, and a rotary atomizer at substantially midpoint potential. What is claimed is: 1. A paint application device, comprising a device for maintaining the spraying device, the sleeve being made of a material having a dielectric strength higher than that of the environment surrounding the ejection device. 16. The paint application device of claim 15, wherein the sleeve has a generally circular cross-section perpendicular to the axis of the sleeve and the ring has a generally circular cross-section perpendicular to the axis of the sleeve. . 17. the ring is generally parallel to the axis of the sleeve;
17. A paint application device according to claim 16, having a generally circular (double) cross section. 18. A device for supplying additional streams of a number of different paints to the rotary atomizer, and a device for selectively controlling which of the different paints flows to the rotary atomizer at a given time; 16. The apparatus of claim 15.