JPS6012915B2 - Equipment for spraying paint or similar materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for spraying paint or the like.

As a paint spray gun, it sprays paint pneumatically.
tjc) Spray gun and paint hydrostatically (hydrostatically)
A spray gun is used.

In pneumatic spray guns, which have been used exclusively for many years, paint is expelled under little pressure through an orifice of circular cross-section, with an internal or It is supported along the same jet of compressed air on the outside and blown by the jet of braces.

Said jet is then flattened by two jets of compressed air that are symmetrical in a plane containing the wisteria line of the cylindrical paint jet and converge toward said paint jet. The pressure of the compressed air used is generally 2 to 3
Within range of Barr.

The pneumatic spray guns described above require large amounts of compressed air, thereby creating a mist of paint and solvent vapor, resulting in significant material loss, and in which some of the solvent is used for painting and surrounding the surrounding area. The presence of electrical equipment capable of producing sparks is a disadvantage in that there is a risk of explosion and that it becomes difficult to breathe the entire atmosphere of the painting workplace.

Hydrostatic paint guns are then used in which the paint is expelled through an elongated orifice at very high pressures, even 20 pressures or more.

The elongated orifice is generally constituted by a hole having a hemispherical head at its end, the end of which is cut with a groove in the form of two planes; The edge of this groove extends through the center of the hemispherical bottom of the hole. Generally “airless”
The hydrostatically spraying gun referred to above avoids the above-mentioned disadvantages of pneumatically spraying guns. However, in the above-mentioned hydrostatic spray guns it is necessary to use a pump capable of dispensing the paint under high pressure and equipment in which all parts, including the seals, can withstand said high pressure. Also, there is a risk of premature wear of the parts, that is, particularly if the sprayed paint is abrasive, the spray nozzle wears out more quickly.

Furthermore, the operation of the hydrostatically spraying gun described above is rough and completely inflexible, as opposed to the pneumatically spraying gun. Of course, research has been done to reduce the hydrostatic pressure of the paints described above.

However, as the pressure decreases, the fan-shaped jet of paint that is ejected from the nozzle will typically become "hom" with a central portion that tends to decrease in width but increase in thickness.
)"It is called. It is impossible to make a good quality painting with the help of mist when the paint is sprayed poorly and is divided into two lateral parts that stain the object to be painted and thus loses its uniformity. Therefore, the above research was not successful. The above development is well known to all technicians and users.

The applicant conducted a comprehensive test in 1964 (Showa 39) and found that various products that are not easy to spray, namely, hydrostatic spraying of various paints, were discharged under hydrostatic pressure. They discovered that this can be improved by impinging the paint jet with two symmetrical jets of slightly pressurized air.

Later, U.S. Pat. No. 3,843,053 disclosed a paint spray gun implementing the above-mentioned improvements.
No. 7 application has been filed. However, the effects obtained by the above improvements are not satisfactory. As a result of new research into this problem using different research methods, the applicant has completed the present invention.

That is, the applicant has proposed that if the above-mentioned flat fan-shaped paint jet is surrounded by a thin veil of slightly compressed air, this air will simultaneously act on the bottom, top and sides of said paint jet, while In a gun that sprays hydrostatically, it is possible to avoid an increase in the thickness and a decrease in width of the central part of the jet and, on the other hand, that the lateral parts of the jet move away from the central part. The fan-shaped jet of paint has a central part where the thickness increases and the width decreases, and two sides called "nno" which are sprayed more roughly than the central part and try to move away from the central part. The idea was that it would be possible to reduce the pressure on the paint while at the same time avoiding separation into parts. As a result of the above considerations, the applicant has determined that the paint pressure of 10 to 100 bar and the
．． It operates under a compressed air pressure of 5 to 2 bar and has the same degree of operating flexibility as a pneumatic paint spray gun.

They succeeded in creating a paint spray gun that sprays hydrostatically. As mentioned above, in conventional hydrostatic paint spray guns, the paint must be delivered under extremely high pressure. If we were to make it as low as possible, we would have a flat fan-shaped paint jet as described above, with a central part where the width tends to decrease and thickness tends to increase, and two side parts. It was not possible to perform high-quality painting because the paint was divided into two parts. According to the present invention, such a low range of paint pressure can eliminate such disadvantages. Additionally, this gun was a huge commercial success. The above invention is disclosed in the present application and Japanese Patent Publication No. 54-8496 (Patent Face No. 976153).

The object of the invention is to surround the jet of paint discharged under hydrostatic pressure with a veil of slightly pressurized air, so that the jet of paint can be divided into a central part and a side part. The object of the present invention is to provide a spraying device for paint or the like, which prevents the paint from separating and does not require the supply of paint under high pressure. According to the invention, there is provided a spray gun with a spray nozzle for discharging a flat fan-shaped jet of paint through a spray orifice, and two air jets arranged symmetrically on either side of said nozzle. an air head including two discharge orifices; a device for supplying relatively high pressure paint from a paint bath to the spray orifice of the spray nozzle; and a means for supplying relatively low pressure compressed air from a compressed air source to the spray nozzle. a device for supplying the discharge orifice, the pressure of the paint being in the range from 10 bar to 3100 bar and the pressure of the compressed air being in the range from 0.5 bar to 2 bar; In order to force the released air to a location immediately in front of the front end of the blow orifice, the air discharge orifice is located behind the blow orifice 3 and oriented toward or substantially along the outer surface of the nozzle so that the jets of low-pressure compressed air do not impinge on each other and on the fan jets of paint; There is provided a spraying device for spraying paint or the like, characterized in that the spraying device is adapted to surround the horizontal stream of water in parallel with it.

In the above-described configuration of the invention, the two air discharge orifices arranged symmetrically on both sides of the spray nozzle are:
Located behind the spray orifice and facing or substantially along the outer surface of the spray nozzle, the jets of low-pressure compressed air do not impinge on each other and prevent paint without colliding with the fan-flat jet of
If the two air ejection orifices are located in front of the spray orifice, the fan jet of paint will surround it. If it is arranged so that it collides with
The pair of compressed air jets can form swirls that envelop the atomized paint, causing it to rapidly splatter backwards, contaminating the spray nozzle, and destroying its uniformity. It becomes impossible to perform good painting due to the rumors surrounding the paint.

In the present invention, Ford No. When using a paint containing glycerin phthalate which flows in a cross-section of 4 with 3 silica sand, the pressure of the paint is 10-20 bar and the air is 1-2 bar through two air release orifices with a diameter of 1 mm. When sprayed, the sloppy jet of paint did not form lateral "horns" and a uniform and good coating could be achieved.

Since the device of the present invention is configured as described above, it produces the following effects.

(i) A fan-shaped paint jet is surrounded by a thin veil of slightly compressed air, so that this air acts simultaneously on the bottom, top and sides of said paint jet, and this jet has a large thickness. It is possible to prevent the paint being sprayed from being divided into a central part where the width is 4. There is no longer any risk that the mist will be inconsistent and the quality of the coating will be poor.

(ii) Even if the pressure of the paint supplied to /Zuru is reduced,
As mentioned above, it is possible to prevent the paint jet from splitting into the central part and the side parts, so all components of the device, including the pump and seals, must be able to withstand high pressure. Furthermore, even if the paint to be sprayed is abrasive, there is no risk of premature wear of the spray nozzle.

(iii) Since the paint jet that scatters from the paint jet to the surrounding area and the false paint mist that bounces off the object to be painted are reduced, the amount of mist when it is scattered is reduced.

Therefore, the atmospheric condition around the worker is improved.
A portion of the slightly compressed air surrounding the paint jet at Ta 0 flows into the paint jet, and this air flow removes atomized paint mist by passing through the nozzle throttle. Next, the particles are further atomized, so a smooth coating film is formed and the quality of the Z coating is improved. The apparatus of the present invention can be effectively used for electrostatic spraying of paint.

In the case of existing types of equipment with hydraulic spray nozzles, the velocity of the liquid paint stream that is injected through the narrow orifice of the nozzle is so high that the sprayed paint particles do not reach the spray head. There is a very high probability that the electrostatic field generated between the electrode or electrodes and the object closest to the ground potential, ie the object to be painted, will not be directly affected.

2. The device according to the invention for the electrostatic spraying of paint or similar liquids likewise comprises a nozzle of an electrically conductive machine and a device for holding the nozzle at a continuous voltage of high value with respect to the ground and the object to be painted. equipment. The initial velocity of the sprayed paint particles can be sufficiently slowed as long as the interaction between the two streams of liquid paint sprayed from the device according to the invention and the streams of compressed air takes place. The various parameters of the device according to the invention can be selected in such a way that almost all the particles are subjected to the direct action of the electric field generated by the charging elements of the spray head, in particular the hydraulic paint spray nozzles. . From this point of view, the device according to the invention, which includes a hydraulic paint spraying nozzle, has the same advantages as an only pneumatic spraying device, but with very low air consumption. In a preferred embodiment of the electrostatic paint spraying device according to the invention, the spray head includes at least one acicular first electrode and at least one second insulated electrode, the first electrode being , the electrostatic spraying 4 nozzles are brought to the same voltage, the tip of the electrode is at the same height as the paint spraying front, or
positioned outside the paint stream so as to be located near the plane of the fan-flat paint stream slightly downstream of the spray front;
The second electrode is connected to the first electrode on the outside of the fan flat bench flow.
a tip of the electrode and a blunt first end located opposite the paint stream and relatively far from the paint stream so as to be directed preferably towards the front of the gun-shaped device in the direction of the object to be painted; and a spaced apart tapered second end.

Preferably, the tip of the first electrode and the first end of the second electrode are aligned perpendicularly to the planar brush flow. Electrodes of the above structure are most suitable for obtaining a useful charge for spray paint in a film, so as to reduce the rate at which the particles dissipate and become waste because they are not directly affected by the electric field, and different electrodes are used. This effectively avoids that the end of the terminal is gradually contaminated by paint, resulting in a rapid decrease in electrical efficiency later on. Electrostatic paint spraying devices are known, in which the spray head includes a hydraulic spray nozzle, a charged first electrode and an insulated second electrode, which electrodes are connected to a fan flat paint stream. Align vertically.

However, in this case the aligned tips of the two electrodes are located slightly upstream of the paint spray front. The electrical efficiency of an electrode increases as it moves away from the nozzle, presumably because the electric field of the hydraulic spray nozzle under voltage perturbs the electric field of other electrodes, and Particles quickly foul the other electrode end when it is located far downstream of the paint spray front. However, according to the invention, the ends of the first and second electrodes are preferably flush with the spraying front, or slightly downstream thereof, so that the ends of the electrodes are rapidly exposed to the sprayed paint. Positioned close enough to avoid contamination. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the paint spraying device according to the invention will be explained in detail below with reference to the accompanying drawings, which show, by way of non-limiting example, an embodiment of the invention.

The gun-type spraying device shown schematically in FIG.
It is composed of a crosshead 1, a main body 2, and a spray head 3.

A threaded tube 5 connects the body 2 with a perforated part 4 that fits externally.
It is installed in the front part (towards the left in Figure 1).

It is preferable that the perforated part 4 can be connected to the delivery part of a paint pump at low or medium pressure by a flexible pipe (not shown), and the suction part of the pump can be connected to the paint tank 7 through the pipe. do. Further to the left of the perforation 4 of the gun-shaped body 2 whose inner side is screwed (FIG. 2), there is a distal end of a rod 10 that is slidably attached along the axis of the cylindrical perforation 8a extending to the left. The tubular charging part 8, through which the cylindrical perforation part 8a extending to the left as a reduction part 8b passes in the direction of the koji, is screwed so as to form a seat for the needle valve 9 carried by the needle valve 9. The right end of the rod 10 that comes out from the main body 2 in a sealed manner is 1
At 1a, a trigger 11 is attached to the gun-shaped body 2 so as to be pivotable.
Connect with. A spring (not shown) forces the rod 10, which is connected to the trigger 11, to the left in FIG. 1, so that the needle valve 9 is seated and ensures the closure of the portion 8b. The portion 8b is
The axial perforation 12a of the ring 12 extends and the ring 12
The rear side (right side in Figure 2) is pressed against the front side of the charging section 8, and the front side of the ring (left side in Figure 2) is connected to the hydraulic pressure, which is not shown in cross-section in Figures 1 and 2. It plays a role of supporting the paint spray nozzle 13. This nozzle 13 has an axial passage aligned with the aforementioned perforations 12 and 8b, which passage opens at the front of the nozzle 13 and has an atomizing slot forming an orifice for spraying. 13a, which slot, in the particular form of embodiment shown, extends at right angles to the plane of FIGS. 1 and 2. FIG. 6 shows an enlarged sectional view of the head shown in FIG. 2, and FIG. 11 shows a sectional view taken along the line phantom--phantom in FIG. Referring to FIG. 11, the shape of the clear atomization slot 13a, the passages 28a, 28
The shape and arrangement of b and the shape of the orifice 23 can be clearly understood. The nozzle 13, and in particular the hydrostatic atomization slot 13a, differs little from the nozzle slots used to date in exclusively hydraulic gun spray devices. However, in the case of the present invention, the nozzle 13 is not made of tungsten carbide, but is made of treated steel if the gun-type spraying device is used for spraying paints etc. that do not have an excessive abrasive load. . Further, the front surface of the nozzle 13 in which the atomizing slot 13a closes is preferably hemispherical and is continuously connected to the truncated conical side surface. Ring 12
The nozzle 13 is further surrounded by an annular member 14, which has a frusto-conical front surface constituting an extension of the tapered front surface of the nozzle 13. The nozzle 13 is fixed angularly in the annular member I4 by a suitable device (not shown). Furthermore, the front part of the tubular loading part 8 (left side in FIG. 2) is surrounded by a collar 15 which is likewise fastened to the internal threading of the front bore of the body 2 in front of the threading of the bagging part 8. The inner diameter of the collar 15 is such that an annular chamber 15a is provided around the front part of the tubular charging section 8. In this case, the annular chamber 15a is provided at the upper part of the gun-type spraying device main body 2, and The compressed air supply pipe 18 and Rendou 0 are connected through a passage (not shown).
The lotus is inserted through another passage 17 and the perforation 16. A valve 33 actuated by the trigger 11 is inserted into the compressed air introduction passage. In the preferred embodiment, tube 18 connects compressed air source 1
It is connected to 9 through a tubular tube (not shown). Furthermore, the passage 17 opens to the front side of the body 2 by a perforation 17a with a reduced cross section, and the connection between 17 and 17a
The adjustment knob 2 is attached so that it can be slid along the axis of the
The needle valve 20a carried on the front end of the rod 20, which is connected to the knob 0b so as to be operated by this knob, serves as a valve seat in which the needle valve 20a is engaged. The adjustment knob 20b and the valve 20a are
used solely for the purpose of optionally reducing the pressure of the compressed air discharged from the orifices or passages 28a and 28b;
As can be seen in FIG. 2, there is no control over the compressed air passing through the annular passage or orifice 23. The provision of an orifice 23 is not essential to the invention; it is preferred in the invention to provide two air ejection orifices symmetrically arranged on either side of the spray nozzle, as shown at 28a, 28b. Although this is essential, the needle valve 20a is provided in order to make it possible to adjust the pressure of the air ejected from the passages 28a and 28b, which are essential components, to a desired value. The pressure of the air ejected from the orifice 23 is a small, almost constant pressure determined by the gap in the orifice 23. Therefore, there is no need to adjust the pressure from the auxiliary orifice 23 (if the ejection pressure from the orifice 23 is too high, the paint (This will destroy the fan-flat shape.) For this reason, the adjusting means consisting of the needle valve 20a is provided only for adjusting the pressure of the air ejected from the passages 28a and 28b. The air head 21 is provided above the nozzle 13 and the annular member 14 and is fixed to the nozzle 13 and the annular member 14 by means of a nut 22 which is tightened into the outer threaded part of the front part of the body 2 and is screwed inwardly. The air head 21 is connected to the material 13,1 at the central perforation.
4, this air head has a frusto-conical inner surface which cooperates with the frusto-conical surfaces of said members 13, 14 to move forward, i.e. to the left in FIG. They are arranged to form an annular Z-shaped passage 23 whose average diameter decreases as it goes towards the end. A groove 24 cut into the outer surface of the annular member 14 passes through the rear end of the annular passage 23 (on the right side in FIG. 2).
As shown in cross-section in FIG. 3, the grooves are formed at regular corners of member 14. In the right direction of FIG. 2, the longitudinal Z-direction groove 24 passes through an annular chamber 25 in which the aforementioned annular chamber 15a is closed. The compressed air packing 26 is located between the rear part of the air head 21 passing above the front end of the collar 15 and the shoulder of the collar 15. Further, the annular member 14 is connected to the nozzle 13 (
The slot 13a of the nozzle (also fixed so as not to rotate with respect to the annular member 14) is oriented in the longitudinal direction so that the slot 13a of the nozzle is arranged at right angles to the plane of FIG. By means of an extending key 27, the air head 2
1 so as not to rotate about the axis of the annular member 14. The front surface of the air head 21 is an atomizing section.

It has a truncated conical surface 21a that tapers in the direction of a point located slightly in front of the cut 13a.
In this embodiment, the orifices of two passages 28a, 28b of approximately circular cross section, which are arranged perpendicular to and on either side of the atomization slot 13a, pass through the truncated conical surface 21a. Compressed air is supplied to the two passages 28a, 28b via conduits 29a, 29b passing through an annular chamber 30 provided inside the nut 22 between the front surface of the main body 2 and the rear surface of the air head 21.

Referring to FIG. 2, the passages 28a and 28b are located on the right side (that is, rearward) of the atomizing slot 13a, which is the spray orifice, and are located on the outer surface of the nozzle 13 (the truncated conical shape of the nozzle 13). The jets of compressed air discharged from the passages 28a and 28b do not collide with each other, nor with the fan-shaped jets of paint. In the embodiment of FIG. 2, these jets of compressed air are directed to the exposed surface (
That is, it collides with the outer surface) and is deflected to the left so as to surround the flat jet of paint that is ejected from the atomization slot 13a in parallel with it. The paint spraying device according to the invention, as described in the preamble with reference to FIG. 1, is used in the following manner.

The paint pump 6 is selectively adjusted to deliver paint to the tube 5 of the gun spray device at a pressure of 10 to 20 bar. Furthermore, the compressed air source 19 is dimensioned to deliver compressed air or another suitable air to the tube 18 of the gun-type spray device at a pressure of the order of 1.5 to 2 bar. Under these conditions, when the user of the gun-type spraying device strongly presses the trigger 11, the compressed air valve 33 closes due to rotational movement of the trigger around its pivot axis 11a, and the end of the sliding rod 10 The needle valve 9, which is held by the needle valve 9, leaves its seat.

The pressurized paint is thus fed into the chamber 4 through the tube 5, from the chamber 4 through the perforations 8a, 8b, 12a to the nozzle 13, and from the nozzle 13 to the atomization slot 13a.
Through the slot, liquid paint is ejected in the form of a fan-shaped jet of liquid paint extending in a plane that includes this slot and is perpendicular to the plane of the page of FIG. This liquid paint stream exits the annular passage 23 and collides with the liquid paint stream slightly in front of the outlet of the atomization slot 13a, and a conical compressed air stream and passages 28a, 28
b, a double jet with two jets separated by a frustoconical surface of the air head 21 so as to exit perpendicularly to the fan-flat jet and converge in the direction of a point located slightly forward of the atomization slot in the same machine. As a result of the action, it is immediately sprayed as extremely fine particles. The reference examples shown in FIGS. 4 and 5 are the same as the embodiment shown in FIG. 1, and therefore are given the same reference numerals as in FIG. 1.

The spray head of the reference example shown in FIG. 4 is the same as that of FIG. 2 except for the following points.

Compressed air is sent to the annular chamber 15a in parallel to the passage 17 through a passage 31 provided at the bottom of the gun-type spraying device main body 2.
Furthermore, the front surface of the air head 21 is a truncated conical surface (21 in FIG.
a), and the two passages 28a, 28b are arranged so as to create a tapered airflow above the localized blast jet, especially at the front point located in front of the atomization slot 13a. It is inclined with respect to the perpendicular to the localized brush jet emerging from the slot 13a. The reference example shown in FIG. 5 is the same as that shown in FIG. 4 except for the following points.

That is, two auxiliary passages 32a, 32b, which are substantially parallel to the passages 28a, 28b, are provided in the front part of the air head 21, and in this case, the auxiliary passages are connected through the same longitudinal passages 29a, 29b, respectively. to supply compressed air,
The auxiliary passages 32a, 32b are arranged in such a way as to produce a concentrated airflow over the already partially injected fan-flat stream at a point located a relatively long distance from the atomization slot 13a. Ru. In the embodiment described above, an advantageous effect is obtained by deflecting a pair of additional air jets by a frusto-conical surface before they impinge on the fan-planar surface of the paint jet. It shows that you can get it.

In the first embodiment (FIGS. 2 and 6), the additional air jet F2 has an atomizing head and the nozzle 1
The atomizing head has a nozzle 13 surrounded by an annular member 14 and is deflected by a frusto-conical part 21a of the air head 21 converging in the direction of the axis of the annular member 3; The front surface of the frustocone forms an extension of the lateral frustocone surface of the nozzle 13.

The blowing head and the air head are arranged in such a way that the two additional air streams F2 are deflected by the frustoconical surface of the nozzle 13 and the annular village 14 surrounding it before impinging on the paint stream. For this purpose, paired passageways 28a and 28b are provided at the free end 14 of the annular member 14.
It is directed convergently towards the frusto-conical surface of the air head 21 which projects somewhat more than a. In the embodiment illustrated in FIG. 7, the air head passages 28a, 28b are oriented perpendicular to the axis of the blowing head.

In the alternative embodiment shown in FIG. 8, the truncated cone formed by the nozzle 13 and the annular member 14 has a sharper angle, so that the passages 28a, 28b can be tilted onto the axis of the spray head. be.

FIG. 9 and FIG. 10 show a reference example and an example in which a gun-type spraying device is modified for use with static electricity. In the case of the reference example shown in FIG. 9, two electrodes are arranged at the front of an air head 21 made of electrically insulating material. The first electrode E, is composed of a conductive member and is embedded in the upper ear of the air head 21 so as to be in contact with the front end of the aforementioned key 27, and in the direction perpendicular to the atomization slot 13a. 21 projecting from the upper ears and terminating in a taper. Projecting from the lower ear-like part of the air head 21, the first
The recessed part of the second electrode E2, opposite the tip of the electrode E, is oriented toward the front of the gun-type spraying device (i.e. to the left in FIG. A conductive protrusion E having a tapered end protruding from the front surface of the air head 21 is fixed. According to the present invention, the tip of the first electrode and the folded end of the second electrode E2 are arranged in a horizontal plane through which the atomization slot 13a passes, that is, the edge of the atomizer injects a fan-flat stream. The two electrodes E,,E2 are aligned perpendicularly to the plane of the paint stream, with their opposite ends located on either side of the paint stream at a relatively short distance from those two planes, and outside the jet itself. It has dimensions such that it is located at .

According to the reference example of the gun-type spray device shown in FIG. The opposite ends of the two electrodes themselves have a spacing of approximately 7 willows.

The mirror-type electrostatic spraying device of the reference example illustrated in FIG.
conductor 3 transmitting the intermediate voltage produced by 3 to the gun-type device
4 is arranged in a manner known per se along the axis of the flexible tube 18a supplying compressed air.

Inside the body of the gun-type device, the conductor 34 is likewise arranged along the axis of the compressed air passage 35b and is connected to a voltage increasing device 36 of the type known in the art under the name "Electro-Gas-Dynamic Pressure Generator". Connect to electrical inlet. The electrical outlet of the voltage increasing device 36 transmits the high voltage produced by the voltage increasing device 36 via a conductor 37 to the tubular charge 8, which, like the ring 12 and the annular member 14, is made of electrically conductive material. Therefore, conductor 3
The high pressure through 7 is transmitted to the hydraulic spray nozzle via members 8, 12 and to the first electrode 31 via members 14, 27. A voltage increase device 36 of the type of electric-gas pressure engine is supplied with compressed air via a passage 35b, at least a portion of the compressed air exiting therefrom being sent to the passage 17 via a passage 35a. , the rest can be re-injected into the atmosphere. The paint spraying device just described with reference to FIG. 9, which shows a schematic diagram, is used in the following manner.

The paint pump 6 is selectively adjusted to deliver paint to the tube of the gun-type device at a pressure of 30 to 50 bar. Furthermore, the compressed air source 19 delivers compressed air or another suitable gas to the tube 18 of the gun-type device at a pressure such that the compressed air exiting the voltage increase device 36 has a pressure of the order of 0.5 to 1 bar. It has the dimensions as provided. Under this condition, when the user of the gun-type device presses the trigger 11 strongly, the movement of the trigger 11 about the pivot 11a causes the sliding rod 1 to move.
The needle valve 9 carried by the end of the needle valve 9 is released from its seat and the compressed air valve 20 is opened.

Thus, the paint supplied to chamber 4 through tube 5 is
The liquid paint flows through the passages 8b and 12a to the nozzle 13, and is formed by the nozzle 13 into a flat fan-shaped jet of liquid paint formed in a plane perpendicular to the plane of the paper of FIG. and is injected through the fin atomization slot 13a. After passing about 10 millimeters through the atmosphere, the liquid paint stream is no longer homogeneous and becomes segmented. This phenomenon occurs or begins more or less at the point where it appears as a line, ie the "atomization front". The operating conditions of the spray gun, i.e. the supply pressures of paint and compressed air, are such that the atomization front is formed substantially in a vertical plane containing the tips of electrodes E and E2, respectively, or slightly upstream of this plane. It is adjusted so that (In this case the contact electrode is located slightly downstream of the spray front). The reason for this selection is explained in the preamble. Despite the low pressure of the paint injected by the nozzle 13 of the gun-type device, below 100 bar, the flat liquid paint stream ejected from the gap of the nozzle exits from the annular passage 23; A conical stream of compressed gas is guided by the conical face of the nozzle 13 and collides with the liquid paint stream slightly in front of the outlet of the atomizing slot 13a, and exits from passages 28a, 28b and also passes through the atomizing slot. Due to the dual action of the two compressed air flows concentrated in the direction of a point located slightly in front of 13a, an extremely narrow jet is produced. Since the first electrode is carried at a high voltage with respect to the ground and an object having its potential, the tip of the first electrode E generates an electric charge due to the corona effect, and the electric charge spreads through its thickness. After passing through the fan-flat spray stream sprayed by the spray nozzle 13 at approximately the same height as the front surface, it is actually all collected by the folded end of the second electrode E2. These conditions are optimal in order to ensure a very effective charging of the sprayed paint or of the particles of the paint being sprayed, in order to be immediately subjected to the electric field effects already described. The electric field collected by the electrically insulated second electrode E2 carries the second electrode at a high potential slightly lower than that of the first electrode E, so that it is injected in the direction of the object at ground potential. A strong electric field is created between the tip Ea and the ground or an object at that potential, in particular a painted object, which directs the ionized paint particles. However, the second electrode E2, which receives a continuous flow of charge, maintains an approximately constant potential, since the tip E emits a corresponding continuous flow of charge in the direction of the nearest object, which is at ground potential. The present invention is not limited to the above-described embodiments, but also includes various types.

That is, for example, the number and arrangement of passages 28a, 28b, E2, E, etc. may be changed, and the number and arrangement of passages 28a, 28b, E2, E, etc.
Instead of arranging the passages only in the equal planes, that is, in the planes of FIGS. 1 to 10, it is possible to arrange them also in another plane, for example in the plane of the jet of a flat bench, or only in this other plane. can. Also, instead of having an annular outlet of uniform thickness, the annular passageway 23, at least near its outlet orifice, may, for example, be in the plane of the paint jet or in a plane perpendicular to this plane (i.e., in FIGS. 1 to 10).
(in the plane of the figure), it may have locally enlarged portions. With the above configuration, for example,
The frusto-conical air flow produced through the annular passage 23 is prevented from forming a relatively thick bead (hom), i.e., along the edges of the flat jet of atomized paint. It is clearly possible to locally intensify the effect exerted by the jet in the required direction. The arrangement of the first and second electrodes illustrated in FIG. 9 is particularly effective, and various types are possible.

For example, the shape and arrangement of the first electrode E and the second electrode E2 can be changed. Similarly, a plurality of first electrodes,
In some cases, a plurality of second electrodes may be provided. It is important for the invention that the tips or ends of all provided electrodes are positioned outside the paint stream at approximately the same height as the spraying front, or slightly downstream of said front in one of the planes of the paint stream. They should be located close to each other. It should be noted that a gun-type spraying device of the type shown in FIG. 10 that applies continuous high pressure to a spraying nozzle for conductive material is an embodiment that does not depart from the scope of the present invention. Instead of constituting the voltage increase device incorporated in the body of the gun-type device with a motor of the electric-gas-operated type, it is also possible to use a suitable type that is operated solely electrically.

Furthermore, instead of incorporating a voltage increase device into the gun-type device, a high-voltage generator may be installed outside the gun-type device, but in this case, a connection cable with less flexibility and high electrical insulation is required. Therefore, it becomes bulky and expensive. In the case of the latter two variants, according to the invention, the compressed air is
It must be fed into the supply tube (tube 18 in FIG. 1) of the gun-type device at bar pressure. The operating conditions of the paint spraying device according to the invention are not limited to those described above in the case of the embodiments illustrated in FIGS. 1 and 8.

The paint delivery pressure can generally be selected in the range from 10 to 100 bar, and the pressure of the compressed air delivered to the passage 17 can be selected in the range from 0.5 to 2 bar. bar to 50 bar, and the pressure of the compressed air is in the range 0.5 bar to 1 bar, the action of the gun-type spray device according to the invention is as shown in FIG. The effect is quite different from that described so far for the embodiments.In fact, in this case the paint sprayed by the hydraulic spray nozzle is under relatively high pressure;
The liquid paint stream emerging from the nozzle can be sprayed in a very fine stream. When using paint pressures of the order of 10 to 20 bar, the spraying device according to the invention can be equipped with a paint pump of the air motor type, which produces a pressure multiplication of, for example, a ratio of 3 or 4.

Also, in the case of relatively high paint pressures of the order of 30 to 5 lbs, the device according to the invention can be equipped with a pump of the same type providing a pressure multiplication ratio of the order of 10 to 15. The use of the pump described above is particularly advantageous when compared to purely hydrostatic spraying systems, which require pumps capable of producing pressure multiplication ratios of the order of 30.

It goes without saying that various modifications may be made to the embodiments described above with reference to the accompanying drawings without departing from the scope of the invention.

For example, to make the nozzle 13, carbide steel (carbide steel) is used to make the nozzle 13.
It is clear that if the use of idesteel is not absolutely necessary, the nozzle 13 and the annular member 14 can be made as a single piece.

Similarly, the variant embodiment shown in FIG. 10, in which the atomizing head abuts with its shoulder 14b the shoulder 21b of the air head,
It can be incorporated into the apparatus shown in FIGS.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view at the height of the spray head of a gun-type spray device according to the first embodiment. FIG. 2 is an enlarged view of the spray head. FIG. 3 is a cross-sectional view taken along the line m--plate in FIG. 1. Figures 4 and 5
The figures are enlarged views showing reference examples of spray heads of gun-type spray devices. FIG. 6 is an enlarged sectional view of the head shown in FIG. 2. 7 and 8 show alternative embodiments of the head, respectively. FIG. 9 is a reference example,
1 is a partial cross-sectional view of an electrostatic gun-type paint spraying device taken at the height of its head; FIG. FIG. 10 is an enlarged cross-sectional view of an embodiment according to the present invention which may be used with the head of the gun-type device shown in FIG. FIG. 11 is a sectional view taken along the phantom--phantom line in FIG. 6. 3...Blow head, 6...Paint pump, 9...Needle valve, 11...Trigger, 13...Liquid paint spray nozzle , 18... compressed air supply pipe, 21.
...Air head, E,,E...electrode. Kong cough J later evening 2 Kong soft 3- 〃. Pogogo. Yuyio.. G. 〇Ti・g. Z. Fig. 8. Matsuyu. 9 Tig. 10. E RgM

Claims (1)

[Scope of Claims] 1. A spray gun equipped with a spray nozzle that discharges a flat fan-shaped jet of paint through a spray orifice, and two air jets arranged symmetrically on either side of the nozzle. an air head including a discharge orifice; a device for supplying relatively high pressure paint from a paint bath to the spray orifice of the spray nozzle; and a relatively low pressure compressed air source for discharging the air. a device for feeding the paint into an orifice, the pressure of the paint being in the range from 10 bar to 100 bar, the pressure of the compressed air being in the range from 0.5 bar to 2 bar, and the pressure of the compressed air being in the range of 0.5 bar to 2 bar; The air discharge orifice is located behind the spray orifice and faces an outer surface of the spray nozzle to force the air to be directed directly in front of the front end of the spray orifice. or substantially along this outer surface so that the jets of low pressure compressed air do not collide with each other and the flat jet of paint, but are parallel to the flat jet of paint. A device for spraying paint or something similar, characterized in that it is adapted to surround the same. 2. In the spraying device according to claim 1,
Apparatus for spraying paint or the like, characterized in that the outer surface of the spray nozzle is substantially conical, concentric with the spray nozzle. 3. In the spraying device according to claim 1,
The air head further includes an annular orifice concentric with the blow nozzle and the symmetrically arranged annular orifice for forcing the discharged air to a location immediately in front of the forward end of the blow orifice. and a device for supplying compressed air to the annular orifice at a pressure approximately equal to the pressure of the compressed air supplied to the two air discharge orifices. attaching device.