A spray nozzle and a spray method

Abstract

The present invention relates to an electrostatic spraying device, in particular to a spray nozzle, comprising a powder outlet pipe, a valve body and an air inlet nozzle, wherein a powder inlet hole is provided at the bottom of the valve body, a main air inlet connection hole and a throat hole are provided at both ends of the valve body, the powder outlet pipe is fixed on the throat hole, the main air inlet connection hole is communicated with the powder inlet hole, a powder outlet hole is also provided on one side of the powder inlet hole, and the powder outlet hole is communicated with the powder outlet pipe; an air jet head is provided at one end of the air inlet nozzle, an air jet hole is provided on the air jet head, and the air jet hole is a through hole, the air inlet nozzle is installed on the main air inlet connection hole, the air jet head does not contact the bottom of the powder inlet hole, and the air jet head is located on one side of the powder outlet hole, and the air jet head and the powder outlet hole are arranged oppositely, and are used to directly spray high-pressure gas to the powder outlet hole. A spray nozzle sets the air jet head on the side close to the powder outlet hole, so that the high-pressure gas directly enters the powder outlet hole, and a stable annular airflow is formed between the air jet head and the powder outlet hole, the powder suction is stable, the pressure fluctuation is small, and the atomization effect is good.

Description

Technical Field

[0001] The invention relates to an electrostatic spraying device, in particular to a spraying nozzle and a spraying method. Background Art

[0002] The working principle of electrostatic powder spraying is almost the same as that of general liquid coating electrostatic spraying, except that powder spraying is dispersed rather than atomized. It is a coating sprayed by an electrostatic powder spray gun, which makes the powder particles negatively charged while dispersing. The charged powder particles are applied to the grounded object under the action of airflow (or other forces such as centrifugal force) and electrostatic attraction, and then heated, melted and solidified into a film. Electrostatic powder spraying is a powder coating method that occupies a dominant position in the field of industrial coating. Electrostatic spraying equipment consists of a spray gun, a spray cup and an electrostatic spraying high-voltage power supply. Both cyclone spray guns and portable electrostatic spray guns are air atomization. They use compressed air and electrostatic force to atomize the paint, so they can spray objects with complex shapes or large areas. However, the existing nozzles have poor atomization effect, large pressure fluctuations, and unstable powder absorption. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a spray nozzle with good atomization effect, small pressure fluctuation, stable powder absorption and good atomization effect. The specific technical solution is as follows:

[0004] A spray nozzle comprises a powder outlet pipe, and also comprises: a valve body, a powder inlet hole is provided at the bottom of the valve body, a main air inlet connection hole and a throat hole are respectively provided at both ends of the valve body, the powder outlet pipe is fixed on the throat hole, the main air inlet connection hole is communicated with the powder inlet hole, a powder outlet hole is also provided on one side of the powder inlet hole, and the powder outlet hole is communicated with the powder outlet pipe; an air inlet nozzle, an air jet head is provided at one end of the air inlet nozzle, an air jet hole is provided on the air jet head, the air jet hole is a through hole, the air inlet nozzle is installed on the main air inlet connection hole, the air jet head does not contact with the bottom of the powder inlet hole, and the air jet head is located on one side of the powder outlet hole, and the air jet head and the powder outlet hole are arranged opposite to each other, and are used to directly spray high-pressure gas to the powder outlet hole.

[0005] Preferably, the diameter of the air jet hole is smaller than the diameter of the powder outlet hole.

[0006] Preferably, the air jet hole is coaxial with the powder outlet hole and the powder outlet pipe.

[0007] Preferably, the distance between the air jet head and the powder outlet hole is smaller than the radius of the powder inlet hole.

[0008] Preferably, the diameter of the powder outlet hole is the same as the inner diameter of the powder outlet pipe inlet.

[0009] Preferably, the powder outlet pipe is a Venturi tube.

[0010] Preferably, an auxiliary air inlet connection hole is provided on the top of the valve body, and the auxiliary air inlet connection hole is communicated with the powder outlet hole through the throat hole.

[0011] A spraying method, in which the high-pressure gas sprayed from the nozzle directly enters the powder outlet hole, and a ring-shaped airflow is formed between the end of the nozzle and the powder outlet hole to suck the powder or liquid into the powder outlet pipe.

[0012] Furthermore, the negative pressure of the powder outlet is adjusted through the auxiliary air inlet connection hole.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The spray nozzle provided by the present invention sets the nozzle on one side close to the powder outlet hole so that high-pressure gas directly enters the powder outlet hole, and forms a stable annular airflow between the nozzle and the powder outlet hole, with stable powder suction, small pressure fluctuation and good atomization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a spray nozzle;

[0016] Figure 2 is a cross-sectional view of a spray nozzle;

[0017] Figure 3 It is a cross-sectional view of the valve body;

[0018] Figure 4 It is a cross-sectional view of the air intake nozzle;

[0019] Figure 5 It is a schematic diagram of the spraying principle of a nozzle in the prior art. DETAILED DESCRIPTION

[0020] The present invention will be further described with reference to the accompanying drawings.

[0021] Embodiment 1

[0022] like Figures 1 to 4 As shown, a spray nozzle comprises a powder outlet pipe 4, a valve body 1 and an air inlet nozzle 2. The powder outlet pipe 4 is a venturi tube, which can accurately control the gas flow rate.

[0023] A powder inlet hole 12 is provided at the bottom of the valve body 1, and the powder inlet hole 12 is connected to the powder barrel through a powder inlet joint 3; a main air inlet connection hole 14 and a throat hole 16 are respectively provided at both ends of the valve body 1, and a powder outlet pipe 4 is fixed on the throat hole 16, the main air inlet connection hole 14 is communicated with the powder inlet hole 12, and a powder outlet hole 13 is also provided on one side of the powder inlet hole 12, and the powder outlet hole 13 is communicated with the powder outlet pipe 4, and the main air inlet connection hole 14, the powder outlet hole 13 and the powder outlet pipe 4 are coaxially arranged.

[0024] The air inlet nozzle 2 is provided with a hexagonal positioning ring 24, and the two sides of the positioning ring 24 are respectively provided with an air inlet thread 22 and a connecting thread 23, the air inlet thread 22 is used to connect with the air inlet joint, and the connecting thread 23 is connected with the main air inlet connection hole 14. An air jet head 21 is provided at one end of the air inlet nozzle 2, and an air jet hole 26 is provided on the air jet head 21, and the air jet hole 26 is a through hole. The other end of the air inlet nozzle 2 is provided with a vent hole 25, which is connected with the air jet hole 26, and the diameter of the vent hole 25 is larger than the diameter of the air jet hole 26, so as to facilitate the processing of the air jet hole 26. The air inlet nozzle 2 is installed on the main air inlet connection hole 14, the air jet head 21 does not contact the bottom of the powder inlet hole 12, and a powder inlet cavity 15 is formed between the air jet head 21 and the bottom of the powder inlet hole 12. The powder inlet cavity 15 facilitates the subsequent formation of an annular airflow to avoid turbulence at the bottom of the powder inlet hole 12; the air jet head 21 is also located on one side of the powder outlet hole 13, and the air jet head 21 and the powder outlet hole 13 are coaxially arranged opposite to each other, and are used to directly spray high-pressure gas to the powder outlet hole 13. Among them, the diameter of the air jet hole 26 is smaller than the diameter of the powder outlet hole 13. The distance L between the air jet head 21 and the powder outlet hole 13 is smaller than the radius of the powder inlet hole 12. The diameter of the airflow formed by the jet hole 26 is small. When the jet hole 26 is close to the powder outlet hole 13, the airflow ejected by the jet hole 26 enters the powder outlet hole 13 before diffusing to a larger diameter range, and the airflow loss is small. Most of the airflow enters the powder outlet pipe 4 to form a negative pressure to absorb powder or liquid. At the same time, the airflow entering the powder inlet hole 12 is small, and it is not easy to generate turbulence in the powder inlet hole 12, thereby ensuring that an annular negative pressure airflow is formed between the jet head 21 and the powder outlet hole 13. The annular airflow is stable, so the pressure fluctuation is small, the powder absorption is stable, and the atomization effect is good. Therefore, it is necessary to meet the requirements that the jet head 21 is close to the powder outlet hole 13, the diameter of the jet hole 26 is smaller than the diameter of the powder outlet hole 13, and the jet head 21 is kept at a certain distance from the bottom of the powder inlet hole 12.

[0025] The diameter of the powder outlet hole 13 is the same as the inner diameter of the inlet of the powder outlet pipe 4 .

[0026] In some embodiments, the top of the valve body 1 is provided with an auxiliary air inlet connection hole 11, which is communicated with the powder outlet hole 13 through the throat hole 16. At this time, there is a gap between the powder outlet pipe 4 and the throat hole 16, and there is also a gap between the end of the powder outlet pipe 4 and the end of the powder outlet hole 13, so that the auxiliary air inlet connection hole 11 is communicated with the powder outlet hole 13 and the inlet of the powder outlet pipe 4. The auxiliary air inlet connection hole 11 is used to pass high-pressure gas, and the high-pressure gas is discharged to the outlet of the powder outlet pipe 4 together with the high-pressure gas sprayed from the gas injection hole 26, forming a stable and continuous negative pressure, thereby ensuring that the sprayed powder or liquid has a good atomization effect and a stable powder output.

[0027] The powder outlet pipe 4 can be directly fixed on the throat hole 16 by means of threads, or can be fixed on the throat hole 16 by means of a threaded sleeve 5 .

[0028] like Figure 5As shown, the air jet hole in the prior art is far away from the powder outlet hole, and most of the gas ejected from the air jet hole is dispersed into the powder inlet hole, forming turbulence in the powder inlet hole, resulting in unstable negative pressure, and thus unable to form a stable airflow, thereby affecting the atomization effect. In the prior art, the atomization effect is mainly controlled by controlling the pressure and flow of the main air intake, the pressure and airflow of the auxiliary air intake, and the structure of the venturi tube. Therefore, the improvement direction of the atomization effect by those skilled in the art is basically limited to the control of the airflow and the design of the powder outlet pipe. It is not thought of controlling the atomization effect by forming a stable airflow. The present invention realizes a stable annular airflow by changing the position of the nozzle head, with stable powder suction, small pressure fluctuation, and good atomization effect.

[0029] Embodiment 2

[0030] A spraying method, the high-pressure gas sprayed from the nozzle 21 directly enters the powder outlet hole 13, and an annular airflow is formed between the end of the nozzle 21 and the powder outlet hole 13 to suck the powder or liquid into the powder outlet pipe 4; the negative pressure of the powder outlet hole 13 is adjusted through the auxiliary air inlet port 11.

[0031] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.

Claims

1. A spray nozzle, comprising a powder outlet pipe (4), characterized in that: Also includes: A valve body (1), wherein a powder inlet hole (12) is provided at the bottom of the valve body (1), a main air inlet connection hole (14) and a throat hole (16) are respectively provided at both ends of the valve body (1), the powder outlet pipe (4) is fixed on the throat hole (16), the main air inlet connection hole (14) is in communication with the powder inlet hole (12), a powder outlet hole (13) is further provided on one side of the powder inlet hole (12), and the powder outlet hole (13) is in communication with the powder outlet pipe (4); An air inlet nozzle (2), wherein an air jet head (21) is provided at one end of the air inlet nozzle (2), an air jet hole (26) is provided on the air jet head (21), and the air jet hole (26) is a through hole. The air inlet nozzle (2) is mounted on the main air inlet connection hole (14), the air jet head (21) does not contact the bottom of the powder inlet hole (12), and the air jet head (21) is located on one side of the powder outlet hole (13), and the air jet head (21) and the powder outlet hole (13) are arranged opposite to each other, and are used to directly spray high-pressure gas toward the powder outlet hole (13); The distance between the air jet head (21) and the powder outlet hole (13) is smaller than the radius of the powder inlet hole (12); An auxiliary air inlet connection hole (11) is provided at the top of the valve body (1), and the auxiliary air inlet connection hole (11) is connected to the powder outlet hole (13) through the throat hole (16); a gap is left between the powder outlet pipe (4) and the throat hole (16), and a gap is also left between the end of the powder outlet pipe (4) and the end of the powder outlet hole (13), and the negative pressure of the powder outlet hole (13) is adjusted through the auxiliary air inlet connection hole (11).

2. A spray nozzle according to claim 1, characterized in that: The diameter of the air injection hole (26) is smaller than the diameter of the powder outlet hole (13).

3. A spray nozzle according to claim 1, characterized in that: The air injection hole (26) is coaxial with the powder outlet hole (13) and the powder outlet pipe (4).

4. A spray nozzle according to claim 1, characterized in that: The diameter of the powder outlet hole (13) is the same as the inner diameter of the inlet of the powder outlet pipe (4).

5. A spray nozzle according to claim 1, characterized in that: The powder outlet pipe (4) is a Venturi tube.

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