JPH0125640Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a rotating cup for an electrostatic coating machine, which uses centrifugal force caused by rotation to spread paint into a thin film, atomizes it at the tip, and sprays out the atomized paint by covering it with a jet of rotating air. It is.

[Conventional technology]

Conventionally, in electrostatic painting, the atomization of the paint, its transmission through the air, and its application to the object to be painted were all performed by electrostatic action, which required an extremely high applied voltage. The disadvantage is that the paint concentrates on sharp parts such as the tips and corners of the object to be painted, resulting in uneven coating.On the other hand, if the applied voltage is lowered, the particles of the atomized paint become coarser, resulting in poor paint finish. There is. Therefore, a rotary cup type electrostatic coating machine as shown in FIGS. 1 to 3 is disclosed in Japanese Patent Publication No. 12305/1983. This device comprises a rotary cup 2 rotated by an air motor 1, the rotary cup 2 comprising:
As shown in FIGS. 2 and 3, inner and outer cylindrical bodies 2a and 2b and an outer cylindrical body 2c are arranged concentrically.
The outer cylindrical body 2b is fixed to a support part 3 that protrudes outward from the expanded tip of the inner cylindrical body 2a, and an outer cylindrical body 2b is attached with a gap from the outer wall surface of the outer cylindrical body 2b. The body 2c is supported by a plurality of wing bodies 5 which are parallel to the rotary drive shaft 4 and formed in the circumferential direction from the inner wall surface of the external cylinder body 2c, and these wing bodies 5 are connected to the external cylinder body. The outer cylinder body 2c is supported by being fixed to the outer wall surface of the outer cylinder body 2b. The rotary cup 2 configured in this manner is screwed onto the rotary drive shaft 4, and the air motor 1 is rotated by compressed air from the rotary air supply pipe, so that the rotary cup 2 is rotated at a rotation speed suitable for electrostatic painting (3500 rpm to 3,500 rpm). The paint dripped onto the inner wall surface of the outer cylinder 2b from the paint supply section 7 is supplied to the inner wall surface of the outer cylinder 2b through a narrow tunnel-like hole 8, and is then rotated at a knife edge section 9 at the tip. Atomized. On the other hand, high-pressure air is supplied from the compressed air jet nozzle 11 to the gap between the external cylindrical body 2b and the exterior cylindrical body 2c via the shaving air supply pipe 10, and this high-speed airflow is caused by the rotational force of the wing body 5. Rotating cup 2
The rotating air jet flow A has a rotational force in the same direction as the rotation direction of the rotary air jet flow A, and this rotary air jet flow A is shaped into an annular cylinder shape by the annular nozzle part 12 and reaches the position of the object to be painted 13 while enveloping the atomized paint. There is a jet stream for the area up to. At this time, since the ejecting direction of the rotating air jet flow A and the scattering direction of the atomized paint are substantially the same, a severe collision between the two does not occur. In addition, 14 in the figure is the exhaust pipe of the air motor 1,
Reference numeral 15 indicates a high voltage cable, and reference numeral 16 indicates a support body.

[Problem that the idea aims to solve]

However, since the rotating air jet A is rotated in a spiral shape by the rotational force of the blade body 5,
Since its rotation direction is the same as that of the rotary cup 2, it is not completely annular and cylindrical, and does not become a high-speed airflow, but merely a low-speed exhaust flow. Therefore, there are disadvantages in that the target atomized paint is not sufficiently enveloped by the rotating air jet flow A, and the dispersion of the atomized paint is not sufficiently promoted due to mixing into the atomized paint. requires separate high-pressure air supplies for and for shaving;
It has various drawbacks, such as a complicated structure and high cost, as well as the need for a large amount of high-pressure air. Therefore, the object of the present invention is to provide a rotary cup for an electrostatic coating machine that can solve the above-mentioned drawbacks.

[Means to solve the problem]

This idea was made in view of the above problem,
An electrostatic coating machine that forms a thin film of paint on the inner wall surface using centrifugal force due to rotation, and covers this thin film of paint with a jet of rotating air that has a rotational force and blows out in a spiral shape, applying an initial velocity to create a jet. The rotating cup consists of an outer cylinder and an inner cylinder that is fitted and fixed into the outer cylinder and forms a cylindrical space between the outer cylinder and high pressure in the cylindrical space. An air supply means for supplying air is provided, and an air stopper is provided for stopping air by bringing the inner circumferential surface of the outer cylindrical body and the outer circumferential surface of the inner cylindrical body into close contact with each other on the proximal end side of the cylindrical space. A plurality of air flow passages formed by the outer circumferential surface of the inner cylindrical body and the inner circumferential surface of the outer cylindrical body are formed non-parallel to the axial direction. An annular injection port with a small gap is formed between the outer cylinder and the inner cylinder to blow out the high-pressure air that has passed through the air flow passage, and the inner surface of the inner cylinder expands toward the tip side. A paint supply means is provided for supplying paint to the inner surface of the inner cylindrical body.

[Effect]

According to the present invention, the centrifugal force caused by rotation forms a thin film of paint on the inner wall surface, and this thin film of paint is covered with a jet of rotating air that has a rotational force and is spouted in a spiral shape, and an initial velocity is applied to make the paint flow into a jet. However, in the rotating cup of an electrostatic atomizer, high-pressure air is supplied to the cylindrical space formed between the outer cylinder and the inner cylinder, and the proximal end of the cylindrical space is connected to an air stopper. Since the air is stopped by the cylindrical space, a high-speed air flow is formed toward the annular injection port in the small gap formed at the tip side of the cylindrical space. When this high-speed air flow passes through a plurality of air flow passages formed by the outer peripheral surface of the inner cylinder and the inner peripheral surface of the outer cylinder, the air flow passages are non-parallel to the axial direction. , the direction of the high-speed air flow is bent from a direction parallel to the axial direction to a non-parallel direction, and is ejected from the annular injection port while rotating in a spiral shape. Due to the reaction of the above action, a stress in a direction opposite to the bending direction of the high-speed air flow acts on the air flow passage, so that the inner cylindrical body provided with the air flow passage is It is rotated in the opposite direction to the jetting direction of the airflow. In this way, the inner cylindrical body rotates in a direction opposite to the direction in which the high-speed airflow is ejected. That is, the inner cylindrical body rotates even without a conventional air motor. Therefore, the paint supplied to the inside of the rotating inner cylinder is formed into a uniform, extremely thin film on the inner peripheral surface of the inner cylinder by centrifugal force, and spreads toward the tip side. It moves toward the tip side along the inner peripheral surface of the inner cylinder, and is atomized and radiated from the tip side by the applied voltage and centrifugal force. The paint atomized and radiated from the tip of the inner cylinder is regulated into a bundle by the spiral high-speed airflow, so the paint does not scatter in unnecessary directions. Furthermore, the axial center of the spiral mixed fluid of paint and air, which is formed by the atomized paint accelerated by the applied voltage and the high-speed air flow ejected at high speed, is A decompression effect occurs. Therefore, this mixed fluid is squeezed by the pressure reduction effect, becomes a tapered bundle-like flow, and is sprayed onto the surface to be coated. Since the radiation direction of the paint sprayed in the form of a mist from the tip of the inner cylindrical body is different from the jetting direction of the spiral high-speed air flow, the particles of both particles collide violently at this collision portion. Therefore, the paint becomes a finer mist and is sprayed onto the surface to be painted.

【Example】

Hereinafter, a preferred embodiment of this invention will be described in detail with reference to the drawings from FIG. 4 onwards. In the rotary cup of the embodiment, a cylindrical inner cylinder 18 is fitted into a cylindrical outer cylinder 17, and a screw ring 20 is screwed into a threaded portion 19 of the inner cylinder 18 that protrudes from the outer cylinder 17 to the outside. Both cylindrical bodies 17 and 18
It consists of fixed. This exterior cylindrical body 17 has an inner flange 21 formed on the peripheral edge on the high-pressure air supply side, and an outer flange 22 having a plurality of air introduction holes 22' perforated on the peripheral edge on the high-pressure air jetting side. is installed protrudingly. On the other hand, the inner cylindrical body 18 has an inner flange 21 of the external cylindrical body 17 sequentially arranged on its outer peripheral surface from the high-pressure air supply side.
an air stop flange portion 23 that is joined to the inner wall circumferential surface and that is in close contact with the inner wall circumferential surface;
An annular groove 25 is recessed to form an annular gap 24 between the inner wall surface of the outer cylindrical body 17 and an annular groove 25 extending in the axial direction to form a large number of high-speed air flow paths 26 with the inner wall surface of the outer cylindrical body 17. On the other hand, a large number of non-parallel flow passages 27 are respectively formed, and the annular groove 25 is bored with four communication ports 28 in the axial direction. Four communication pipes 31 are extended in a perpendicular direction from a mounting pipe 30 which is located in the direction and communicated and connected to the high pressure air supply pipe 29, and each communication pipe 31 is fixed in alignment with the communication port 28. has been done. Further, the inner wall surface of the inner cylinder 18 has a tapered shape that widens toward the tip on the high-pressure air jetting side, and this tip is fixed in a protruding state from the outer cylinder 17, and the tip edge An injection port 32 with a small annular gap is formed between the outer peripheral surface and the inner peripheral surface of the tip of the outer cylinder 17. still,
The electrostatic coating machine to which this rotary cup is applied has a configuration in which a high-pressure air supply pipe 29 is rotatably supported on a support 33, as shown in FIG. Insert the tip into the inner cylinder 1
8. To explain the operation of the embodiment device configured as described above, high pressure air sent through the high pressure air supply pipe 29 passes from the attachment pipe 30 through each communication pipe 31 and reaches the annular gap 24 from the communication port 28, and this annular gap 24 is sealed with the air stopper flange 23, so that the air flows through each high-speed air flow path 26 to the injection port 3.
The annular air flow is ejected from the air outlet 2 as an annular air flow, and the negative pressure caused by this air flow forms an annular air flow with a sufficient amount of air by the outside air sucked in from the air introduction hole 22'. In such a case, since each high-speed air flow path 26 is formed non-parallel to the axial direction of the rotary cup,
The high-pressure air pumped in the axial direction acts on the side wall surface of the annular groove 25 to apply rotational force to the rotary cup, causing the rotary cup to rotate about the high-pressure air supply pipe 29 as a support axis. At this time, the annular airflow ejected from the injection port 32 is also ejected as a rotating airflow, but the direction of rotation is opposite to the direction of rotation of the rotating cup. On the other hand, the paint dripped from the dripping nozzle 35 is stretched by the centrifugal force caused by the rotation of the rotary cup, and is gradually formed into a thin film covering the inner wall surface of the inner cylinder 18, and along the taper of the inner wall surface. The centrifugal force gradually transforms the paint into a uniform, ultra-thin film and moves it toward the tip of the inner cylinder 18, and along with the electrostatic atomization effect caused by the high voltage applied to the rotary cup, the outer periphery of this thin film paint Under the atomization effect of the annular cylindrical rotating high-speed air flow injected from the injection port 32,
It is atomized into fine particles, applied with an initial velocity, and jetted over a section up to the object to be coated. When the number of rotations of the rotary cup was measured while changing the supply pressure of air supplied from the high-pressure air supply pipe 29 from 1 kg/cm ² to 4 kg/cm ² , the results shown in Table 1 were obtained. However, the air supply pressure in Table 1 is
The high pressure air supply pipe 29 has a length of 3.5m and an inner diameter of 6mm.
This shows the air supply pressure at the high pressure air source connected to the piping. From this experimental result, the rotating cup of the present invention has a rotation speed (3500 rpm to 11000 rpm) suitable for electrostatic painting even without a conventional air motor.
It was confirmed that this was obtained in the same way as with the conventional rotating cup. Of course, by changing the experimental conditions, it is quite possible to obtain a rotation speed of several hundred to tens of thousands of revolutions per minute.

[Table] Therefore, according to the rotary cup of the electrostatic atomizer according to the present invention, the same degree of centrifugal force as that of a conventional rotary cup equipped with an air motor can be obtained, so the paint can also be atomized to the same degree. It is. According to the present invention, the rotating direction of the high-speed airflow spirally injected from the tip of the rotating cup and the scattering direction of the atomized paint scattering from the tip of the inner cylinder 18 are as follows.
Since they are not in the same direction, they collide violently and further atomize the atomized paint. Therefore, the extremely fine mist of paint mixes with air and reaches the object to be coated.

[Effects] As mentioned above, according to the rotary cup of the electrostatic coating machine of this invention, the supplied high-speed airflow flows through the airflow passages provided on the outer peripheral surface of the inner cylinder that are non-parallel to the axial direction. Since the inner cylindrical body rotates by bending the inner cylindrical body, it is possible to rotate the inner cylindrical body and generate centrifugal force inside the inner cylindrical body even without an air motor. Then, due to the action of the centrifugal force and applied voltage applied by the rotating inner cylindrical body, the paint, which is atomized in the same way as in the conventional case, is combined with a high-speed air stream that is spirally injected from the tip of the rotating cup. Violent collision turns into finer atomized paint and is emitted onto the object to be painted, so unnecessary solvent is evaporated and the paint can be applied thickly without dripping on the painted surface, creating a uniform coating pattern. There is an effect that allows you to obtain
It is possible to obtain extremely noticeable effects without causing uneven coating. Further, since the atomized paint is prevented from scattering due to the bundle of high-speed airflow spirally injected from the tip of the rotary cup, the efficiency of paint usage is improved. In addition, the rotary cup of this invention is applied because the rotary cup is rotated by high pressure air from a single high pressure air supply source, and the air flow after being rotated forms a rotary annular air flow. The electrostatic coating machine has the advantage of being extremely economical as it eliminates the need for an air motor, greatly simplifying its configuration, and greatly reducing the amount of high-pressure air used. As described above, the rotating cup of this invention is an epoch-making device that has various remarkable practical effects.

[Brief explanation of drawings]

Fig. 1 is a side view of a conventional electrostatic coating machine, Figs. 2 and 3 are a cutaway side view of the same rotary cup as above, and a sectional view taken along the line A-A in Fig. 2, and Figs. 4 to 6. 4 shows an embodiment of the rotary cup of the electrostatic coating machine of this invention, FIG. 4 is an exploded perspective view, FIG. 5 is a front view, FIG. 6 is a rear view, and FIG. 7 is a rotary cup of this invention. FIG. 2 is a cutaway side view of the applied electrostatic coating machine. 17... Exterior cylindrical body, 18... Inner cylindrical body, 23...
...Air stop flange, 24...Annular gap, 25...Annular groove,
26... High speed air flow path, 27... Distribution path, 29...
...High pressure air supply pipe, 30...Mounting pipe, 31...Communication pipe, 32...Injection port.

Claims (1)

[Claims for Utility Model Registration] Paint is made into a thin film on the inner wall surface by the centrifugal force caused by rotation, and this thin film paint is covered with a jet of rotating air that has a rotational force and is ejected in a spiral shape to add an initial velocity. In the rotating cup of the electrostatic atomizer that produces the jet, there is an outer cylindrical body and an inner cylindrical body that is fitted into and fixed to the outer cylindrical body and forms a cylindrical space between it and the outer cylindrical body. An air supply means for supplying high-pressure air to the cylindrical space is provided, and the inner circumferential surface of the outer cylindrical body and the outer circumferential surface of the inner cylindrical body are brought into close contact with each other on the proximal end side of the cylindrical space. An air stopper is provided for stopping air, and a plurality of air flow passages formed by the outer circumferential surface of the inner cylinder and the inner circumferential surface of the outer cylinder are formed non-parallel to the axial direction; An annular injection port with a small gap is formed between the outer cylindrical body and the inner cylindrical body on the front end side of the cylindrical space to eject the high-pressure air that has passed through the air flow passage, and the inner cylindrical body A rotary cup for an electrostatic coating machine, characterized in that the inner surface is expanded toward the tip side, and a paint supply means for supplying paint to the inner surface of the inner cylinder is provided.