JPH02268854A - Thermal spraying device - Google Patents

Abstract

PURPOSE:To increase a thermal spraying area and to uniformize a film thickness distribution by directing both nozzles so as to incline the transverse center lines of both planar jet air in the directions opposite to each other with respect to the central axis of a thermal spraying and to intersect with each other while converging a part thereof. CONSTITUTION:A thickness center line A1 of the planar jet air 31, 31 is inclined toward a central axis Q of the thermal spraying and a part thereof is converged to delineate a V-shaped air chamber. A flux W is melted to droplets by an arc discharge or gas combustion within this chamber. The droplets are then fed into jet air 31, 31 by the weak air flow to derive the droplets and are thereby fined and simultaneously cooled. Transverse center lines A2, A2 of the respective jet air 31, 31 incline opposite to each other and intersect with each other while partly converging and, therefore, the droplets are fined and dispersed in the air flow consisting of a front aggregated air flow 32 and a intersecting air flow 36 intersecting without converging. As a result, an oblong or elliptical thermal spraying pattern is exhibited on the surface or a base material and the pattern area thereof is expanded to about 3 times or above the pattern area of the conventional device.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a thermal spraying apparatus with an improved supply form of compressed air for atomizing.

(b) In conventional thermal spraying equipment, both arc thermal spraying equipment and gas-type thermal spraying equipment use compressed air for atomizing (a↑omizinq) to miniaturize metal droplets and spray them onto the surface of the base material. Blows out toward the vicinity of the generation position. As conventional techniques for supplying compressed air for atomizing, two systems are widely known in arc thermal spraying apparatuses: an outer envelope type and a volumetric type.

The envelope type sprays compressed air from an annular nozzle to generate an arc discharge inside a conical air sphere, and a thermal spraying apparatus of this type is known, for example, in Japanese Patent Laid-Open No. 167472/1983. In addition, there is another nozzle that is provided with another nozzle behind the center of the nozzle and blows out auxiliary jet air from this nozzle toward the center of the arc (Japanese Patent Publication No. 56-101).
Publication No. 03).

The penetrating type is equipped with a main nozzle that ejects main jet air behind the center of the arc area, and performs atomizing by causing the linear main jet air ejected from the main nozzle to directly act on metal droplets. This type of device is, for example, JP-A-61-'
It is described in No. 181560. Also, special public service in 1986
Publication -18463 discloses that a pair of auxiliary nozzles is provided outside the arc area in addition to the main nozzle, and auxiliary air is jetted from both nozzles toward the intersection of the tips of the old material, and this auxiliary air acts directly on the metal droplets. Atomizing is described in which the atomizing is carried out in cooperation with the main jet air.

A gas-type thermal spraying apparatus thermally melts old wire rod or powder material by gas combustion, and atomizes and sprays the resulting droplets so that they are surrounded by jet air (in some cases, a gas jet stream).

(c) Problems to be Solved by the Invention In the conventional thermal spraying apparatus as described above, regardless of whether the external arc spraying method or the penetrating type arc spraying method or the gas-type melting method is used, as shown in FIG. There was a disadvantage that the thermal spray pattern P2 was approximately circular, and only a small thermal spray area was obtained.

By increasing the amount of air ejected from the nozzle, the sprayed area can be expanded to some extent. However, in this case, in arc spraying, the arc portion of the old material is supercooled by a large amount of jet air, which tends to cause a pinch phenomenon, making it difficult to stably perform arc spraying. In addition, in both arc and gas spraying methods, a strong reverse air flow is formed on the surface of the base material, which increases the amount of droplets that bounce back without adhering to the base material, and the amount of droplet adhesion loss increases rapidly.

Usually, it is said that the appropriate distance between the thermal spraying device and the base material is about 20 cm, but by increasing this distance, the thermal spraying area can be expanded to a certain extent. However, in this case, the adhesion force of the fine droplets to the surface of the base material decreases, and the peel resistance of the sprayed coating decreases.

A second problem with the conventional apparatus is that the distribution of the sprayed fine droplets is non-uniform.

As shown in FIG. 3, the film thickness t of the circular thermal spray pattern P2
However, the central part is thicker than necessary, and the peripheral edge is so thin that the required thickness cannot be obtained. Therefore, there were disadvantages such as unevenness in the thickness of the thermally sprayed coating in the in-plane direction, making it impossible to form a homogeneous coating, and large variations in protection performance resulting in lack of reliability. Furthermore, since the sprayed droplets are concentrated in the center, heat tends to accumulate in the center, and the thermal spray coating may peel off due to the difference in thermal expansion between the center and the surrounding areas.

The small spray pattern area mentioned at the beginning of the water ring means that
It also greatly affects work efficiency. Of course, it is natural that it takes a long time to form a sprayed coating of a predetermined thickness on a fixed area, but this is not enough. Typically, the base material is subjected to a blast treatment to activate the surface before thermal spraying.

The activated surface is in a state where it is easily oxidized, and it is necessary to complete the thermal spraying operation within 2 to 4 hours after blasting, depending on the material of the base material. Therefore, when the area of the base material exceeds a certain value, it is not possible to form a film within the above-mentioned time, and extra auxiliary work is required, such as stopping the thermal spraying work and performing activation treatment with a liquid agent. becomes.

This invention was proposed in view of the above, and by improving the supply form of compressed air for atomizing, it is possible to expand the thermal spray area several times and make the film thickness distribution uniform. The purpose is to obtain a highly efficient thermal spraying device.

(d) Means for solving the problem In this invention, as a supply form of compressed air, jet air 31.31 is ejected from a pair of nozzle ports 29.29,
A basic form is adopted in which both jet air 31 and 31 partition a V-shaped air chamber.

Then, it was decided that both jet airs 31 and 31 would be inclined in opposite directions and intersect in the same way as crossed flat belts intersect.

Specifically, each plane jet air 31 .
A pair of nozzle ports 29.29 forming a 31 are arranged so that the thickness center line A1 of both jet air 31.31 is directed toward the thermal spraying center axis Q at a position forward from the droplet generation position (arc intersection) O of the weld metal W. Inclined and both jet air 31.
The width direction center lines Δ2 and A2 of 31 are inclined in opposite directions with respect to the thermal spraying central axis Q, and both jet air 31.31
Both nozzle holes 29.
29, and can be applied to both arc thermal spraying equipment and gas thermal spraying equipment.

(e) Operation The thickness center line A1 of both jet airs 31, 31 is inclined toward the molten steel central axis Q, and a portion of both jet airs 3L31 converge, thereby defining a V-shaped air chamber. In this air chamber, the melt W is turned into droplets by arc discharge or gas combustion.

The droplets are driven into the jet air 31.31 by a weak air stream derived from the jet air 31.31, where they are atomized and cooled at the same time.

At this time, each jet air 3L 31 is inclined in the opposite direction, and intersects while converging a part thereof.

Therefore, the droplets are scattered in the collective airflow 32 in front of the convergence part R.
Then, the jet air 3L and the jet air 3L are atomized and dispersed in the airflow consisting of the intersecting airflow 36 that does not converge but intersects. As a result, the surface of the base material exhibits an oval or elliptical thermal spray pattern P1 as shown in Figure 3, and the pattern area can be expanded to over 2.5 to 3 times that of the conventional thermal spray pattern P2. Ta.

(f) Embodiment FIGS. 1 to 8 show a first embodiment in which the present invention is applied to an arc melting 9A apparatus. In Fig. 4, the arc spraying apparatus performs arc spraying using a round wire-shaped welding material W, and the old material path is set so that the welding material W passes through the rectangular box-shaped case 1 in a vertically parallel attitude. A welding material feeding mechanism 2 is provided in the center of the interior of the case 1, and a nozzle 3 for spouting compressed air for totomizing is arranged on the outer surface of the front end of the case 1.

In FIG. 5, the case 1 includes a metal case main body 4 with an opening on the side, an insulating block 5.6 fixed to the front and rear ends of the case main body 4, and an opening that can be opened and closed via a hinge 7. M8, a bracket 9 for the nozzle 3 that covers the front surface of the front insulating block 5, and the like. M8
is maintained in a closed position by a latch 10, and can be easily opened by sliding the latch 10 against a spring 11. Further, the bracket 9 can be removed from the insulating block 5 by loosening the screw 12, which is convenient for replacing the nozzle 3.

In order to feed and guide the welding material W, a pair of upper and lower kite tubes 14 are fixed to the insulating block 6 on the rear side, and these kite tubes 14
A feeding hole 15 is connected to the front insulating block 5 in correspondence with the above. Roughly, a terminal 16 is provided continuously in each feeding hole 15,
An arc guide tube 17 is screwed and fixed to the front surface of the terminal 16. A power supply line is connected to both terminals 16, and a positive current is applied to one of them, and a negative current is applied to the other.

As shown in FIG. 4, the upper and lower arc guide tubes 17 are arranged in an inclined position so that their tip ends approach each other vertically, and the upper and lower weld metal W is moved toward the arc intersection O on the front outer surface of the nozzle 3. Direct you. During this direction change, the welding material W comes into pressure contact with the inner wall of the arc guide tube 17, thereby ensuring the application of arc current.

The melt feeding mechanism 2 includes a front insulating block 5 and a guide pipe 1.
4, and simultaneously feeds the upper and lower welding materials W toward the front of the case. In Figures 4 and 5,
The welding material feeding mechanism 2 includes a drive roller 18 that is rotatably supported by the upper and lower walls of the case body 4, and a drive roller 18 that transports the welding material W to the drive roller 18.
It is composed of a presser roller 19 that presses the roller 19, a motor 21 that rotationally drives the drive roller 18 via a set of gears 20, and the like.

The drive roller 1B is formed by fixing an insulating roller 23 to a roller shaft 22. A metal ring 24 having a V-shaped cross section is fixed to the upper and lower parts of the insulating roller 23, and the welding material W is sandwiched between the ring 24 and the presser roller 19 and is forcibly driven to be fed. To prevent slippage, the peripheral surface of the metal ring 24 is knurled.

The presser roller 19 is also made of an insulator like the drive roller 18, and is arranged one above the other in correspondence with each insulated roller 23.

The pressing roller 19 is rotatably supported by one end of the spring arm 25, and the driving roller 18 is moved by the elastic force of the spring arm 25.
It is press-fitted and energized. The base end of the spring arm 25 is fixed to the inner surface of the lid 8.

As shown in FIG. 4, the motor 21 is housed in a grip 26 fixed to the bottom surface of the case, and is activated when a switch (not shown) is turned on, and the rotational power is transmitted to the drive roller 18 through the gear 20. tell.

The nozzle 3 is formed in the shape of a vertically long hollow box, and a recess 28 is provided in the left and right center of the upper half of the nozzle 3 to avoid the arc guide tube 17, and a nozzle port 29 is provided in each of the left and right front end walls separated by the recess 2B. It is open. 30 is a joint for connecting an air hose.

The nozzle opening 29 is a part of the small holes 2 forming a vertical straight line.
9a, the jet air merges after being ejected to form planar jet air 31, 31 each having an I-shaped cross section. The jet air 31 is oriented such that its thickness center line A1 is inclined toward the thermal spraying center axis Q located in front of the arc intersection O (droplet generation position) of the weld metal W, and as shown in FIGS. As shown in Fig. 8, the width direction center lines A2, A2 of both jet airs 31.31 are inclined in opposite directions with respect to the thermal spraying central axis Q, and both jet airs 31.31 partially converge. intersect (first
Figure). Here, the thickness center line A1
The angle θ1 between is 12 to 2, although the angle does not matter.
It is preferable to set the angle range to 4 degrees. Further, the inclination angle θ2 of the widthwise center line A2 is not limited as long as it has a convergent portion R and intersects with it, but it is preferably set in an angle range of 5 to 40 degrees.

In order to reduce the number of openings of the small holes 29a and reduce air consumption, the vertical height positions of the left and right nozzle ports 29 are shifted vertically in relation to the direction of inclination of the width direction center line A2.

Specifically, as shown in FIG. 6, the nozzle opening 29 on the left side as viewed in the figure is biased slightly upwards with respect to the thermal spraying center WBQ, and the nozzle opening 29 on the right side is biased downwardly. ing.

The jet air 3L 31 ejected from the left and right nozzle ports 29, 29 forms a V-shaped air curtain in plan view, and an air chamber is defined inside the V-shaped air curtain.

The arc intersection point O of the melt material W that turns the melt material W into droplets is set on the thermal spraying center axis Q near the center in the front-rear direction inside the air chamber. In FIG. 2, reference numeral 32 indicates a collective airflow formed ahead of the convergence part R of the jet air 31.

When arc spraying is performed using the nozzle 3 configured as described above, the droplets of the weld metal W are made fine and dispersed by the air flow circulation consisting of the cross air flow 36 that intersects the collective air flow 32 without converging.
As shown in FIG. 3, an oval thermal spray pattern P1 was obtained. The short axis length of this thermal spray pattern P1 was almost the same as the diameter of the thermal spray pattern P2 by the conventional apparatus, and the long axis length L was approximately three times the diameter. This means that the droplets of -m were dispersed over a wider range, and it was confirmed that the film thickness was uniform in the surface direction in the actual thermal spray pattern P1 as well. In addition, the thermal spray pattern P1
The long axis is inclined by an angle α with respect to the vertical central axis of the thermal spraying device, which means that the axial center line A2 of the jet air 31 is inclined, and the airflow after crossing is twisted in one direction. It seems to be in storage.

FIGS. 9 and 10 show a second example and a third example of the arrangement pattern of the small holes 29a, respectively.

In the second embodiment shown in FIG. 9, the left and right nozzle ports 29.2
Match the vertical height position of 9 and insert both nozzle holes 29.29
were placed symmetrically. In addition, in the third embodiment shown in FIG. 10, in addition to the nozzle ports 29 and 29 described in the first embodiment,
An auxiliary nozzle port 34 is provided on the outside thereof.

In addition to the above, the nozzle opening 29 may be formed in a series of grooves as in the fourth and fifth embodiments shown in FIGS. 11A-8 and 12A-8. At this time, the air tank 35 in the nozzle 3 needs to be installed at an angle, so that the jet air 31.
31 can have the same directivity as the jet air of the first embodiment. This groove-shaped nozzle opening 29 makes it possible to supply a large amount of nozzle air, making it applicable to ultra-large thermal spray machines. In addition, as shown in the figure, No. 11A-8
The fourth embodiment shown in the figure uses a pair of nozzles 3.3 in combination, and the fifth embodiment shown in FIG. 12A-8 uses one nozzle 3 provided with a pair of nozzle ports 29.29. .

The inclination angle of the width direction center line A2 of the jet air 31 may be different on the left and right sides.

The old material W may be in the form of a belt, and in this case, the jet air 31 is ejected along the longitudinal direction of the old material W.

(v) As described in detail, in the thermal spraying apparatus of the present invention, the planar jet air 31.3 is emitted from the pair of nozzle ports 29.29.
1 is ejected to melt the old material in an air chamber surrounded by both jet air 31. 29.29 was directed diagonally.

As a result, droplets are dispersed in the jet air flow during atomizing, and a wide oval or elliptical spray pattern P1 is obtained, and the pattern area can be expanded several times compared to conventional patterns. Ta.

Therefore, according to the thermal spraying apparatus of the present invention, a thermal spray coating can be efficiently formed in a short time, and the productivity of the film forming operation can be significantly improved. In particular, even when the base material area is large,
A thermal spray coating can be formed all at once before the surface condition deteriorates. Furthermore, since the thickness of the thermally sprayed coating in the plane direction is made uniform, the quality of the coating can be significantly improved, and variations in protection performance can be eliminated and reliability can be improved.

Since no thick film portion is formed, peeling of the film due to localized heat concentration can be eliminated.

[Brief explanation of drawings]

1 to 8 show an embodiment of the thermal spraying apparatus according to the present invention, FIG. 1 is a side view 1 showing the jet air jet form in principle, FIG. 2 is a plan view thereof, and FIG. A front view showing the thermal spraying pattern, FIG. 4 is a vertical side view of the thermal spraying device, FIG. 5 is a sectional view taken along the line V-V in FIG. 4, FIG. 6 is a front view of the thermal spraying device, and FIGS. 7 and 8. are shown in cross-sectional views taken along lines VH-VI[ and -■ in FIG. 6, respectively. FIG. 9 and FIG. 10 are front views showing a second embodiment and a third embodiment of the nozzle, respectively. 11A and 11B show a fourth embodiment of the nozzle, with FIG. 11A being a front view and FIG. 11B being a side view. 12A and 12B show a fifth embodiment of the nozzle, with FIG. 12A being a front view and FIG. 12B being a side view. 3...Nozzle, 29...
Nozzle port, 31...Jet air, 3
2...Collective airflow, 36...
・Cross airflow, W......Welding material, O...
...Global droplet generation position (arc intersection), Q...
...Thermal spraying center axis, Pl...Thermal spraying pattern, A1...Thickness center line, A2...
・・・・・・Center line in width direction

Claims (1)

[Claims] (1) A pair of nozzle ports 29, 29 each forming planar jet air 31, 31 are arranged with the droplet generation position O of the weld material W in between, and both jet air 31,
The thickness center line A1 of the jet air 31 is inclined toward the thermal spraying center axis Q located forward from the droplet generation position O of the weld metal W, and the widthwise center line A2 of both jet airs 31, 31 is inclined toward the thermal spraying center axis Q. A thermal spraying apparatus characterized in that both nozzle ports 29, 29 are oriented in opposite directions to each other so that both jet airs 31, 31 partially converge and intersect.