JPS59147672A - Electric arc melt-spraying method - Google Patents

Abstract

PURPOSE:To increase adhesion strength of a molten metal onto a surface to be melt-sprayed by calculating a heat input by the feed speed of a metallic wire on a positive pole side and arc current and setting the respective feed speeds of both metallic wires so as to maximize the heat input to be supplied to both metallic wires. CONSTITUTION:Metallic wires 1, 2 on a positive pole side and a negative pole side are respectively fed and an arc is generated between the top ends of both metallic wires to melt both metallic wires. Compressed air 7 is fed to a melt spraying gun 5 to spray the molten metal to an object 8 to be melt-sprayed. Both metallic wires are fed respectively at the individual feeds speeds and the feed speeds are adjusted, then the arc currents of the arc are measured with respective ammeters 9, 10. The heat input to be supplied to both metallic wires is calculated from the arc currents and the feed speeds. The feed speeds of both metallic wires are respectively set to as to maximize the heat intput.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention involves feeding a positive metal wire and a negative metal wire, generating an arc between the tips of both metal wires, and melting both metal wires by the arc. The present invention relates to an electric arc thermal spraying method in which molten metal is attached to a surface to be thermally sprayed by spraying compressed gas, and the object is to improve the adhesion of molten metal to the surface to be thermally sprayed.

In the conventional electric arc spraying method, a positive metal wire and a negative metal wire are each fed by a single motor, and a DC arc is generated between the tips of both metal wires to melt them. The molten metal of both metal wires is deposited on the surface to be thermally sprayed by the blowing of compressed gas.

However, according to this type of conventional electric arc spraying method, the feeding speeds of both metal wires are equal, and the electric arc spraying is performed under the spraying conditions of the same feeding speed. The current conditions are such that they are set with only film thickness control in mind, and the adhesion of the sprayed coating is not taken into consideration at all. For this reason, the adhesion force of the thermal sprayed coating varies, which may cause the thermal sprayed coating to peel off.
This results in defects.

Considering the cause of this from the perspective of arc phenomenon, the positive electrode, (111
This is thought to be due to the fact that the melting state of the metal wire is different between the negative electrode side and the negative electrode side, and the melting metal temperature is also light. Therefore, it is necessary to set the feeding speeds of the positive metal wire and the negative metal wire to appropriate speeds.

This invention was made with the above points in mind,
A positive electrode side metal wire and a negative electrode side metal wire are each fed, and an arc is generated between the tips of the white metal wire, and the white metal wire is melted by the arc, and the compressed scum is blown and melted. In the E-arc thermal spraying method, each of the white metal wires is fed at its own feeding speed, and the feeding speed of each of the white metal wires is adjusted to increase or decrease the metal. In addition to measuring the arc current of the arc, the heat input supplied to the white metal wire is calculated based on the two feeding speeds and the arc current, and the adhesion force of the molten metal to the sprayed seedlings is calculated. The electric arc thermal spraying method is characterized in that the image feed speed at which the determined heat input value is maximized is selected, and the two metal wires are fed at one of the two feed speeds.

Therefore, according to the electric arc spraying method of your invention,
By calculating the heat input from the feeding speed of the positive metal wire, the feeding speed of the negative metal wire, and the arc current,
The feeding speed of each white metal wire can be set so that the heat input supplied to the white metal wire is maximized, and if melting is carried out under the relevant thermal spraying conditions, the temperature of the molten metal will be raised and the In order to increase the adhesion of the molten metal to the sprayed surface, it is necessary to calculate the heat input for each material of the white metal wire (and then select the feeding speed for each material of the white metal wire). By doing so, it is possible to produce a thermally sprayed coating with good adhesion.

Next, the present invention will be explained in detail with reference to the drawings showing one embodiment thereof.

In Figure 1, (1) and (2) are the positive metal wire and the negative metal wire, and (3) and (4) are the positive metal wire (1) and the negative metal wire (2), respectively. Both feed rollers (3)
.

(4) are each driven by an individual motor, and the feeding speed can be adjusted individually. (5) is a thermal spray gun, in which the tip wire (1) of each of the white metal wires (1) and (2) fed by both feed rollers (3) and (4) and the negative metal wire ( 2) and drives the DC power supply (6), a DC arc is generated between the tips of the white metal wires (1) and (2) in the thermal spray gun (5), and the arc causes the white metal wire to The tips of (1) and (2) melt. (7) is supplied to the thermal spraying gun (5), and the molten metal of the white metal wires (1) and (2) is sprayed by the DC arc onto the object to be thermally sprayed (8).
Compressed air is blown onto the surface of the arc. (9) and (]0) are voltage meters and ammeters for measuring arc voltage and arc current.

In the above configuration, when a DC arc is generated between the platinum metal wires (1) and (2) that are fed sequentially, the platinum metal wires (1) and (2) melt, and the compressed air (7) Predetermined thermal spraying is performed by spraying molten metal onto the object (8) to be thermally sprayed.

By the way, when the above-mentioned thermal spraying was carried out, the object to be thermally sprayed (8)
It is believed that the higher the temperature of the molten metal, the greater the adhesion force of the sprayed coating in the spray gun (5).

(2) depends on the heat input supplied; the greater the heat input, the higher the temperature of the molten metal, and therefore the greater the adhesion of the sprayed coating.

The heat input Q is the feeding speed of the metal wire (1) on the positive electrode side (v−l) and the feeding speed of the metal wire (2) on the negative electrode side (v−l).
−, arc ↑I, where ■ is the current, there is a relationship shown in the following equation.

In other words, the total heat input Qh when the electrical resistance of the white metal wires (1) and (2) is large is also the total heat input Qh when the electrical resistance of the white metal wires (1,) and (2) is small. Qc is. In addition, ■1η-j is the equivalent voltage at the positive electrode, V
ln-- is the equivalent voltage that reaches the negative electrode, and 1 is the electrical resistance.

Here, since both equivalent voltage \rmJ-, VITI-O, and electrical resistance T are physical property values, both metal wires (1)
+ Arc current ■ and both feeding speeds y for each material in (2)
By measuring −j−, v−, it is possible to estimate the increase or decrease in the total heat input Q, and therefore, it is possible to estimate the increase or decrease in the total heat input Q.
), (2) determines its feeding speed v'-1-,'
V- is changed appropriately, the arc current ■ of the DC arc generated at that time is measured, and the equation (1) or (
By calculating the heat input Q using the formula 2) and selecting both feeding speeds v+ and v- that maximize the heat input Q, the maximum heat input Q can be obtained and the adhesion force of the sprayed coating can be increased. Recognize.

Next, the experimental results of this invention will be explained with reference to the drawings from FIG. 2 onwards.

What is shown in these drawings are both metal wires (1).

This is a diagram showing the relationship between the heat input Q and the adhesion force of the film obtained by appropriately adjusting the feeding speed in (2).
1) + (2) is made of a material with high electrical resistance, that is, stainless steel%'d (SUS 308). In the figure, ○ indicates when the arc voltage is 30V, below ◎ indicates 35V, and ・ indicates when the arc voltage is 30V. It is 40V. In addition, Figure 3 shows that both metal wires (1* (2) are made of a material with low electrical resistance).
In other words, it is a case where +il, 11 is formed with aluminum.
It is V. As is clear from FIGS. 2 and 3, the adhesion of the sprayed coating increases as the heat inputs Qh and Qc increase.

Therefore, the thermal spraying conditions for achieving good adhesion of the thermally sprayed coating are determined by the respective feeds iq v+, v−h, J: and the heat input Qh from the arc current ■ of both metal wires (1) and (2). , it is clear that it can be set more easily by calculating Qc, and both metal wires (1),
By feeding each of (2) at a feeding speed that maximizes heat input, it is possible to improve the adhesion of the molten metal to the object to be thermally sprayed (8).

[Brief explanation of drawings]

The drawings show one embodiment of the electric arc spraying method of the present invention, with FIG. 1 being a block diagram, and FIGS. 2 and 3 showing the relationship between heat input and film adhesion, respectively. (1) Positive electrode side metal wire, (2) Negative electrode side metal wire, (7) - Compressed air, (8) - Object to be thermally sprayed. Agent Patent Attorney Fujita 1'1h fat section = 37 ]O Heat input Qh ('A'S/cm) λ% Qh (W-min/m) 3rd Kaoru λ% Qc (A・min/m)

Claims (1)

[Claims] ■ The positive electrode side metal wire and the negative electrode side metal wire are each fed, and an arc is generated between the tips of the two metal wires, and the two metal wires are melted by the arc, and the molten metal is melted by spraying compressed gas. In an electric arc spraying method in which the metal wires are deposited on a surface to be thermally sprayed, both metal wires are fed at respective feeding speeds, and the arc current of the arc is measured by adjusting the feeding speed of each of the two metal wires. At the same time, the heat input supplied to both curved metal wires is calculated based on the feed speed and the arc current, and the value of the heat input that determines the adhesion force of the molten metal to the sprayed surface is determined. Select the above-mentioned two feeding speeds that are the maximum,
An electric arc thermal spraying method, characterized in that both of the metal wires are fed at the respective feeding speeds.