JPH0448821Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] In electrostatic painting, the present invention relates to a pin electrode for an electrostatic painting gun having an electrode that charges atomized paint and forms an electric field directed toward an object to be coated.

[Prior Art] Spray guns for electrostatic painting generally have a high-voltage electrode arranged in contrast to air spray or airless spray, and the electrode generates high-voltage static electricity and forms an electric field on the object to be coated. The coating efficiency is improved by the electric effect.

This electrode is effective in the form of a thin pin that extends from the center of the spray, and in air spray type electrostatic guns, a pin electrode that protrudes toward the center of atomization ahead of the center of the paint nozzle is often used. There is.

As the pin electrode penetrates through the center of the paint nozzle, a thin wire (for example, a wire with a thickness of 0.5 mm) is used, and since the paint passes through it, it is generally made to be highly hard by heat treatment. It is.

[Problems to be solved by the invention] As described above, since the pin electrode is a long and thin wire that protrudes from the tip of the spray nozzle, it may come into contact with a handgun during handling, causing it to bend or break. In this case, a normal electrostatic coating effect may not be obtained, or the spray state may be disturbed, which may adversely affect the coated surface.

Therefore, it is necessary to handle it with extreme care, and there are problems such as covering it with a cover to protect it when it is not in use. In addition, if the eyelid is bent, it must be straightened immediately, and if that is not possible, it must be replaced including the attached parts, resulting in unnecessary effort and work being interrupted. That was also a problem.

[Means and effects for solving the problem] The present invention uses a straight member of shape memory alloy that maintains a superelastic region at room temperature for the pin electrode that protrudes forward from the nozzle opening of the air spray electrostatic hand gun that is the problem. The gist is that . It is desirable that the properties at room temperature, for example 15° C., be such that when stress is removed, the material returns to its original shape and maintains a superelastic region. Shape memory alloys include, but are not limited to, Ni-Ti alloys such as nickel-titanium alloys.
A unidirectional shape memory alloy was used.

[Example] FIG. 1 shows a cross-sectional view of the atomizing section of an electrostatic air spray gun. The pin electrode 1 of the present invention is attached to the tip of a needle valve 2, as shown in FIG. A paint nozzle 3 is detachably attached to the tip of the spray gun body 10, and an air cap 4, which is combined with the paint nozzle 3 to form an atomizing section, is also detachably attached by a cover 5. . This type of configuration is already known and is also shown in Utility Model Application Publication No. 58-161658. In order to charge the pin electrode 1 with a high voltage, the rear part of the needle valve 2 is connected to a high voltage source by an electrical conductor. Other parts are made of insulators.

The pin electrode 1 of the embodiment is made to protrude from the tip of the resin needle valve 2, and its rear part is tightly fitted to and electrically connected to the conductive rear needle 6. The pin electrode 1 is made of a shape memory alloy made of a nickel-titanium alloy, which has a unidirectional property and has a superelastic region that returns to its original shape even when external stress is applied at room temperature. In this case, the shape maintains a straight line at room temperature, for example around 15 degrees Celsius, where normal work is done, and if stress is applied below atmospheric temperature, it will remain distorted and deform, but it will return to its original straight shape once the temperature returns to normal. It is.

[Effect of the invention] With the structure described above, the long and thin pin electrode protruding from the tip of the electrostatic gun remains in the superelastic region at room temperature, even if it may be bent by hitting another object due to an unexpected accident. Because it quickly restores itself, it can always be used as a pin electrode that protrudes directly onto the tip of the spray nozzle.

Therefore, there is no need for maintenance for bending or breaking the pin electrode, which conventionally required time and effort, and it is possible to prevent deformation of the spray pattern, coarsening of particles, and deterioration of the electrostatic effect due to pin electrode failure.

[Brief explanation of the drawing]

FIG. 1 shows a tip portion of an electrostatic coating gun showing an embodiment of the present invention, and FIG. 2 shows a detailed view of a pin electrode portion. 1... Pin electrode, 2... Needle valve, 3... Paint nozzle, 4... Air cap.

Claims (1)

[Claims for Utility Model Registration] 1. A paint spout and a needle valve that comes into contact with and separates from the inner sheet of the spout to control the spout of paint, and atomizes the spouted paint and improves the atomization of the atomized paint. In an electrostatic painting gun that is equipped with a pin electrode for electrostatic coating using voltage static electricity, the pin electrode that protrudes from the paint nozzle's spout at the tip of the needle valve and extends forward maintains a superelastic region at room temperature. The pin electrode of an electrostatic painting gun is characterized by being made of a straight shape memory alloy. 2. The pin electrode according to claim 1, which uses a shape memory alloy whose stress/strain curve at normal temperature is, for example, 15° C. and has a superelastic region.