JPH0147230B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a rotating atomizer consisting of a mushroom-shaped boss placed at the free end of a rotating shaft, and a bell-shaped body attached to the boss and concentrically surrounding the boss, In that case, an electrostatic paint spray gun is used in which paint is sent to the back of the boss through an inlet pipe, dispersed from the outer edge of the boss to the inner surface of the bell by centrifugal force, and sprayed from the edge of the bell. Regarding.

Such a paint spray gun equipped with a rotating atomizer has been known for a long time and is used in many fields. During operation, it is unavoidable that from time to time paint scum remains in the spray head and must therefore be cleaned. In this case, the solvent-containing cleaning liquid is generally supplied through the paint inlet line, in particular while the spray head is being rotated. This spray head cleaning is particularly valuable when transferring from one paint to another. In reality, after the spray gun stops, paint residue does not only form on the original paint path, that is, on the back of the boss and on the inside of the bell-shaped body, but also on the front of the boss, and in that case, this residue flows along the paint path. It was found that the cleaning solution could not capture it. Paint adhesion to the front of the boss is especially important when the spray head is
Negative pressure is created inside the paint spray cone when rotating at speeds above 4000 rpm, which causes some of the sprayed paint droplets to be drawn inside and transported to the front of the boss in the opposite direction to the spray direction. This is attributable to this. In addition, in order to remove this paint residue, the front of the boss must be cleaned manually or by spraying a jet of cleaning liquid from the front. It's against driving.

The object of the invention is to improve a rotary atomizing body of the type mentioned at the outset in such a way that it is capable of an automatic cleaning process which captures all areas of the atomizing body that are prone to dirt, in particular also the front face of the boss. This object can be achieved by the means described in claim 1.

According to the invention, therefore, an inlet line for the cleaning liquid with two outlet openings is additionally provided. In this case, one of the outflow openings is on the back of the boss, and the cleaning liquid coming out from there takes almost the same route as the paint sprayed during normal operation, so this cleaning liquid covers the back of the boss and the inside of the bell-shaped body. Washed. Since the other outlet opening is located approximately in the center of the front face of the boss, the cleaning liquid coming out of it is dispersed over the front face of the boss by centrifugal force, cleaning this front face of the boss, and then this cleaning liquid is applied to the inner surface of the bell. Sent. By correspondingly controlling the valves of the paint inlet line and the cleaning liquid inlet line, it is possible to incorporate an automatic cleaning step between the paint spraying steps, in which case the cleaning is very effective. , paint can be replaced very quickly.

Embodiments of the present invention shown in the drawings will be described below.

In the drawing, 10 is the tip of the gun tube of the paint spray gun. The gun tube 10 is closed with a flange 11 which is pierced through the center by a rotating shaft 12. Rotating axis 1
2 is placed in the gun tube 10 and is driven by a compressed air motor 13, which is shown only schematically, and supports a mushroom-shaped boss 14 at its free end. The boss 14 has a spray bell-shaped body 1 concentrically surrounding it.
5 is attached. Valve 1 on the wall of gun tube 10
A paint inlet line 16 with a diameter 7 is running, the opening 16a of this paint inlet line 16 being directed towards the back side 14a of the boss 14. The supply of high-voltage energy to the spray bell 15 takes place, for example, via the rotary shaft 12 or a conductive wire (not shown).

The illustrated gun with atomizing head is of conventional construction up to this point. For operation, the rotary shaft 12 together with the boss 14 and bell-shaped body 15 is rotated by the motor 13, a high voltage is applied, and the valve 17 is opened. The paint then flows under low pressure through the line 16 and through the opening 16a on the back side 1 of the boss 14.
4a. There, the paint is dispersed due to centrifugal force and thrown outwards onto the inner surface 15a of the bell 15. From there, the paint reaches the edge of the bell in the form of a film, from where it is atomized under the action of centrifugal force and the action of an electrostatic film and is conveyed to a workpiece (not shown). The rotational speed of the spray head is then, for example, between 20,000 and 4,000 rpm.

According to the invention, a further inlet line 18 with a valve 19 is provided in the gun tube 10 . This conduit 18 continues to a hole 20 in the flange 11 and opens into an annular flow path 21 between the motor shaft 12 and the boss 14 . From this annular flow path 21, an annular gap 2
2 communicates with the back surface 14a of the boss 14, and the hole 23
communicates with a small hole 24 in the front face 14b of the boss 14 along the motor shaft 12.

Line 18 is used to introduce cleaning liquid. When valve 19 is opened, cleaning liquid enters annular channel 21 through line 18 and hole 20. A portion of the cleaning liquid flows from the annular channel 21 through the gap 22 to the back surface 14a of the boss 14, where it is evenly distributed on the back surface 14a by the step edge 14c, and from there the cleaning liquid flows to the inner surface 15a of the bell-shaped body 15. sent and sprayed from its edges. The other part of the cleaning liquid is in the annular flow path 2.
1 through the hole 23 to the small hole 24, from where it is dispersed over the front surface 14b of the boss 14, and this part of the cleaning liquid reaches the inner surface 15a of the bell-shaped body 15 and is sprayed from the edge of the bell-shaped body. . In that case, if the part of the cleaning liquid flowing through the gap 22 is to be used to clean the back surface 14a of the boss, and the part of the cleaning liquid flowing through the hole 23 is to be used to clean the front side of the boss, the inner surface 15a of the bell-shaped body is used. is washed away with all of the cleaning solution.

Annular flow path 2 that separates the cleaning liquid into two outflow paths
1 further includes an annular gap 2 running along the motor shaft 12.
5 to a compressed air motor, by means of which compressed air can be delivered to the flow path 21 to assist in the outflow of the cleaning liquid. The introduction of compressed air also provides other advantages. That is, when the valve 17 is opened and the valve 19 is closed during paint atomization, a small amount of compressed air passes through the annular gap 25, the annular channel 21, and the hole 23 into the small hole 2.
4 and the resulting negative pressure created in front of the boss 14 is avoided, thereby avoiding the front face 14b of the boss.
The adhesion of paint to is reduced, further thereby
It is ensured that no paint build-up occurs within the stoma 24 itself.

Practical experiments have shown that when valve 19 is opened and the cleaning liquid is introduced, the rotating spray body is cleaned very quickly and very reliably, so that after a short time valve 19 is closed again and valve 17 is It could be opened again, specifically loaded with another paint, to continue the spraying process. Very good results are obtained, since drying of the metal rack paint in the spray head is avoided, especially if the solvent is introduced at certain times, when spraying metal rack paint solutions is hitherto very dangerous. Of course both valves 17 and 19
It is possible to automate the cleaning process by simply controlling accordingly.

In addition, when spraying colloid lacquer paints and water-soluble lacquer paints, there is a problem in that the lacquer particles are already dry before reaching the workpiece, resulting in very poor adhesion of the lacquer paint particles to the workpiece. . Furthermore, on the other hand, such easy coatings cannot be strongly diluted with water so that pre-evaporation of water is completely avoided. Therefore, in the past, questions were asked about spraying in a highly humid atmosphere. In this case, an air humidity of at least 60% is maintained in the spray chamber at a very high cost. According to the present invention, this problem can be easily solved. That is, during the spraying process, the inlet pipe 18 is connected to the water inlet pipe, and a fine water mist is ejected from the boss, which prevents the easy paint particles coming out from the edge 15a from drying. In the same way, the so-called APS (Aqua-
When spraying powder (powder suspension), powder can be sprayed from the spray edge 15a and water can be sprayed from the boss. In order to clean the spray head after the spraying process, the inlet line 18 is connected to a cleaning liquid line.

The invention is capable of many variations, particularly with respect to the structural configuration of the introduction of the cleaning medium along the motor shaft.
For example, grooves or grooves can be provided. Furthermore, the cleaning step can also be carried out in conjunction with a conventional cleaning bush, which allows recovery of the cleaning medium.

[Brief explanation of drawings]

The drawing is a sectional view of the tip of a paint spray gun with a rotary atomizer according to the present invention. 10... Gun tube, 11... Flange, 12... Rotating shaft, 13... Compressed air motor, 14... Boss,
15...Bell-shaped body, 16...Paint introduction pipe, 17...
... Valve, 18 ... Cleaning liquid introduction pipe, 20 ... Hole, 2
1... Annular channel, 22... Annular gap, 23...
Hole, 24...small hole.

Claims (1)

[Claims] 1. A mushroom-shaped boss placed at the free end of the rotating shaft;
It has a rotating atomizer consisting of a bell-shaped body attached to the boss and concentrically surrounding the boss, in which case the paint is sent to the back of the boss through the introduction pipe and is sprayed by centrifugal force from the outer edge of the boss. In an electrostatic paint atomizing gun which is distributed on the inner surface of a bell and is sprayed from the edge of the bell, it is provided with an inlet line 18 for cleaning liquid having two outlet openings 22, 23, one outlet being The opening passage 22 is formed between the boss 14 and the bell-shaped body 15 and is formed of an annular cavity opening at the back surface 14a of the boss.The other opening passage 23 is formed between the rotation shaft 12 and the boss 14 An electrostatic paint spray gun equipped with a rotating spray body, characterized in that it consists of an annular cavity formed between the boss front faces 14b and opening approximately at the center of the boss front face 14b. 2. The introduction pipe 18 for the cleaning liquid is connected to an annular passage 21 formed on the outside of the rotating shaft 12 via a hole 20, and the annular passage 21 is connected to the one outlet opening passage 22 and the rotating shaft 12. The electrostatic paint spray gun according to claim 1, wherein the electrostatic paint spray gun is connected to the holes 23 running along the boss and opening into the small holes 24 of the boss front surface 14b. 3. The rotation shaft 1 is inserted into the annular flow path 21 through the annular cavity 25 between the rotation shaft 12 and the flange 11 arranged outside the rotation shaft 12 and sealing the inside of the gun.
2. The electrostatic paint spray gun according to claim 2, wherein compressed air is supplied from a compressed air motor 13 that drives the electrostatic paint spray gun. 4. Claim 1, characterized in that a cleaning liquid dispersion edge 14c is provided on the back surface 14a of the boss.
The electrostatic paint spray gun according to any one of Items 1 to 3. 5. The electrostatic paint spray gun according to any one of claims 1 to 4, characterized in that the introduction pipe 18 for the cleaning liquid is connected to a water source or a solution source.