JPS6053111B2 - Remelting treatment method for thermal spray coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for remelting a thermally sprayed coating formed on the surface of an object to be treated.

In order to form a sprayed coating of, for example, a self-storing alloy on the surface of a workpiece by thermal spraying, the surface of the workpiece is first roughened in a pretreatment step, and then the surface of the workpiece is roughened. After spraying a self-storing alloy as a thermal spraying material on the surface of the surface, and then remelting the formed sprayed film of the self-storing alloy,
Four finishing steps are required to finish the surface of the coating. Among the above steps, the remelting treatment of the self-storing alloy sprayed coating is an important step for making the sprayed coating non-porous and completely fusing the coating onto the surface of the object to be treated.

This remelting process involves remelting the self-storing alloy sprayed coating formed on the surface of the workpiece by heating it with a heat source such as an oxygen-acetylene flame sprayed from a torch. Conventionally, processing was carried out manually by workers.

That is, the worker uses a torch to heat the surface of the sprayed coating, visually observes the surface condition, and manually manipulates the torch so that the coating becomes glossy and oily-looking due to the heating. and was moving on the surface of the film.

However, the above-mentioned operations have no quantitative standards and rely on the intuition of the operator, which requires skill.Moreover, the thermal spray coating may be overheated or underheated, resulting in unmelted parts of the coating. There was a problem. From the above-mentioned viewpoints, the present invention is capable of remelting a thermally sprayed coating formed on the surface of a workpiece without causing overheating or unmelting of the coating, and which does not require skill. This technology provides a method for remelting thermal sprayed coatings that can be easily and accurately automatically remelted using a heat source. , the moving speed of the heating heat source or the object to be treated is determined based on the relationship between the obtained measurement value and the maximum and minimum heating temperatures of the remelting surface, which are set in advance according to the characteristics of the thermal spray material forming the thermal spray coating. It is characterized by its control. Next, the method of the present invention will be explained based on the drawings.

FIG. 1 is an explanatory diagram of the method of the present invention, in which 1 is a workpiece on which a thermally sprayed coating has been formed, 2 is a table on which the workpiece 1 is placed and can be moved in the horizontal direction, and 3 is a table above the workpiece 1. Object to be treated 1
A heat source such as an oxygen-acetylene flame, an oxygen-hydrogen flame, a plasma flame, a high-frequency induction heating, a laser, etc. is used to heat the heat source 3. 4 is a heat source moving device that freely moves the heat source 3 in the horizontal direction.

The thermally sprayed coating 1 on the workpiece 1 on which the thermally sprayed coating is formed is remelted by the heat source 3, and the temperature of the remelted surface 5 is constantly measured by the thermometer 6.

The thermometer 6 may be a non-contact radiation thermometer, a light thermometer, a two-color high thermometer, or a thermocouple. 7 is
This is a controller for instructing the table 2 on which the workpiece 1 is placed or the heat source moving device 4 to move at a predetermined speed based on input from the thermometer 6.

The controller 7 has a built-in microcomputer that stores mathematical formulas using temperature as a variable, and based on the value input from the thermometer 6,
Calculations are performed using the stored mathematical formulas, and the results are output to the table 2 or the heat source transfer device 4. The stand 2 or the heat source moving device 4 is the controller described above. In response to the output from 7, it moves at a speed corresponding to the temperature of the remelted surface 5 measured by the thermometer 6 and moves to heating the unremelted surface of the object to be treated, thus causing the object 1 to be heated. The sprayed coatings are successively remelted one after another.

In addition, in the above processing, the heat source 3 is fixed and the object 1 to be processed is
Whether to move the table 2 on which the workpiece 1 is placed or to fix the table 2 on which the workpiece 1 is placed and move the heat source 3 depends on the shape of the workpiece 1 and the type of the heat source 3. can be selected as appropriate.

Next, the method of this invention will be explained in more detail with reference to Examples.

FIG. 2 is an explanatory diagram of the remelting processing apparatus used in this example. The sample to be processed 1 has a side of 100Tn and a thickness of 1-S. A nickel-based self-fusing alloy (MSFNi3) 50f was sprayed as a spraying material using a high-frequency plasma flame to form a sprayed coating.

The thermal spray coating was remelted using a high frequency plasma flame as described above as the heat source, and thermal spraying and remelting were performed in a series of operations.

8 is a high-frequency plasma gun; 9 is a high-frequency generator; the high-frequency plasma flame 1 is sprayed from the high-frequency plasma gun 8 to spray the thermally sprayed coating on the workpiece 1 placed on the sample stage 12;
It was heated at 0 to remelt it.

The sample stage 12 on which the object to be processed 1 is placed is movable in the x-axis direction and the y-axis direction by an x-axis direction drive motor 13 and a y-axis direction drive motor 14. Therefore, the thermal sprayed coating of the object 1 to be treated was completely remelted.

The temperature of the remelted surface 5 of the object to be processed 1 is continuously measured by the radiation thermometer 11, and the measurement signal is passed through the noise filter 1.
5. Input to controller 7 via linearizer 16.

The controller 7 performs calculations using a built-in microcomputer based on the measurement signal, and instructs the motor output section 17 to drive the X-axis motor 13 or the Y-axis motor 14 at a predetermined speed. FIG. 3 shows the heating locus of the high-frequency plasma flame on the object 1 to be processed, and a movement pattern was set by the microcomputer of the controller 7 so that the plasma flame apparently moves on the surface of the object 1 to be processed.

Plasma flame starting position S. For x-axis movement span, y-axis movement span Y. is set in advance as a constant, and only the moving speed x of the plasma flame in the X-axis direction is determined by the output of the radiation thermometer 11. The x-axis direction movement speed Ux is determined by the control voltage Vx of the X-axis direction drive motor 13, and the control voltage JEVX is determined by the control voltage Vx of the X-axis direction drive motor 13.
The following (1) and (2) stored in the microcomputer of
) was calculated using the formula.

Note that the moving speed 0y of the plasma flame in the y-axis direction is also determined by the control voltage ``y'' of the y-axis direction drive motor 14, but in this embodiment, the control voltage ``y'' is constant. ■x=■0X
A... (1) In the above equation, VO is the operating voltage corresponding to the preset maximum rotation speed of the x-axis direction drive motor, the control output ratio of the No. A 1x-axis direction drive motor, and t is the radiation thermometer. 11, the average temperature (°C) of the remelted surface measured within a unit time, TH is the maximum heating temperature of the remelted surface preset according to the characteristics of the sprayed material that forms the sprayed coating, TL is the lowest heating temperature, n is a constant for taking into consideration the characteristics of the self-fluxing alloy during melting, and C1 and C2 are constants for correcting the A value.

In Figure 4, TH: 1280, T Muni 1230, C1:1
．． 0, C2: 0.0, and the relationship between the t value and the A value when the n value is 1, 2, 5, 8, and 20 is shown.

As can be seen from the drawing, when the t value is T≦t≦TH, the A value changes from 0 to 1. That is, the higher the temperature of the remelting surface, the faster the plasma flame moves, and the lower the temperature of the remelting surface, the slower the plasma flame moves. Further, when t<TL, A=-0.0 and the plasma flame stands still, while when TH<t, A=1.0 and the plasma flame moves at the maximum speed. The A value was set to 1.0 when the plasma flame was separated from the object to be treated and the temperature indication of the remelting surface could not be obtained. The maximum heating temperature TH and minimum heating temperature TL of the remelting surface are very important because the remelting process will be carried out in a steady state within this temperature range, and the appropriate temperature should be determined depending on the characteristics of the thermal spray material. There is a need.

The movement of the plasma flame relative to the workpiece must be done at such a speed that once the remelting surface reaches the optimal melting temperature, it will not be overheated beyond that temperature; in other words, the movement speed must change rapidly as the remelting surface becomes hotter. There is.

Since the temperature of such a remelting surface changes depending on the characteristics of the self-fluxing alloy sprayed onto the workpiece, the constant n was taken into account when calculating the A value. As is clear from FIG. 4, by changing the n value, the degree of change on the high temperature side can be arbitrarily selected.

However, as the n value increases, the movement becomes ON-OFF, and there is a possibility that a continuous surface state may not be obtained. Furthermore, the optimum processing temperature and the speed of melting and spreading on the remelting surface vary depending on the properties of the thermal spray material. Therefore, the above n
It is necessary to determine an appropriate value depending on the melting characteristics of the self-fusing alloy. The control voltage Vx of the x-axis direction drive motor 13 is determined by selecting appropriate values for the maximum heating temperature TH and minimum heating temperature T and the constants N, cl, and c2, respectively, and based on this, the control voltage Vx of the x-axis direction drive motor 13 is determined. The object moves in the x-axis direction at a speed 'C5x, and the above-mentioned operations are performed continuously based on the temperature of the remelting surface that is continuously measured by the radiation thermometer 11, thereby causing the thermal spraying of the object to be treated. The coating could be easily and accurately automatically remelted without overheating or unmelting.

In the above-described embodiments, the case where the object to be processed is a rectangular flat plate has been described, but the method of the present invention is not limited to flat plates, but can be applied to objects of any shape.

FIG. 5 shows an example in which a cylindrical object 18 is remelted by the method of the present invention, and the rotational speed of the cylindrical object 18 is
By keeping C5R constant and controlling its axial moving speed 02 by the temperature of the remelting surface, or conversely by keeping the axial moving speed 0z constant and controlling its rotational speed 'C5R, It is possible to perform a remelting process. FIG. 6 shows an example of remelting a disk-shaped object 19 using the method of the present invention, in which the circumferential rotational speed of the disk-shaped object 19 is constant, and the radial direction of the disk-shaped object 19 is constant. The moving speed r is controlled by the temperature of the remelting surface, or conversely, the moving speed 0R in the radial direction is kept constant and the rotational speed 0R in the circumferential direction is controlled.
It is possible to carry out accurate remelting treatment by controlling the heat source or movement pattern of the object to be processed in advance, even if the object to be processed has an irregular shape. As a result, the method of the present invention can perform appropriate remelting treatment.

As described above, according to the method of the present invention, when remelting a thermally sprayed coating formed on the surface of a workpiece, the temperature of the remelting surface is continuously measured, and this temperature is quantitatively measured. As a standard, by moving the workpiece or heat source at a speed corresponding to this temperature and performing the remelting process, overheating or unmelted areas will not occur on the remelting surface, and the work will be easier. Many excellent industrial effects are brought about, such as being able to perform automatic re-melting treatment simply and accurately without the need for tempering, and being able to form a thermally sprayed coating with high adhesion.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the principle of the method of this invention, Fig. 2 is an explanatory diagram of the remelting processing apparatus used in the embodiment of the method of this invention, Fig. 3 is a diagram showing the heating trajectory for the object to be processed, FIG. 4 is a diagram showing the relationship between the t value and the A value, and FIGS. 5 and 6 are explanatory diagrams showing other embodiments of the method of this invention.

Claims (1)

[Claims] 1. A thermally sprayed coating of a self-fusing alloy formed on the surface of an object to be treated is continuously heated and remelted by a heat source directed toward the thermally sprayed coating by the movement of the heat source or the object. In the method for remelting a thermally sprayed coating, the temperature of the remelting surface of the thermally sprayed coating heated by the heat source is continuously measured, and the obtained measurement value and the temperature of the thermal spraying material forming the thermally sprayed coating are measured in advance. A method for remelting a sprayed coating, comprising controlling the moving speed of the heat source or the object to be treated based on a relationship between a maximum heating temperature and a minimum heating temperature of the remelting surface set according to characteristics.