CN106967943A - A kind of thermal spraying molding control method of the knife-edge comb tooth coating of non-uniform thickness - Google Patents

Abstract

The invention discloses a kind of thermal spraying molding control method of the knife-edge comb tooth coating of non-uniform thickness.It is programmed design by six axis robot, realize the accurate control of spray gun and the angle (θ) of comb tooth split, and pass through substantial amounts of optimization and checking test, the optimal θ angles of research spraying knife-edge comb tooth and the suitable walking path of spray gun, the Discrete control to knife-edge comb tooth different zones coating layer thickness is realized, the comb tooth coating for the technical requirements for meeting Pu Hui companies is prepared.The optimal θ angles of present invention spraying knife-edge comb tooth are 40 °, and both sides one cycle above and below the selection of spray gun walking path is while the mode of depositing coating.

Description

A control method for thermal spraying of knife-edge grate coating with non-uniform thickness

technical field

The invention relates to a thermal spraying forming control method of a knife-edge grate coating with a non-uniform thickness, and belongs to the technical field of surface protection.

Background technique

In order to improve the efficiency of the engine, reduce energy consumption, and increase the thrust, it is necessary to control the gap between the stator and the rotor of the engine and seal the gas path. At present, the sealing coating technology is generally used. Sealing coatings are divided into two categories, one is a soft coating (abrasive coating) on the stator part, and the other is a hard coating (actively abrasive coating) on the rotor part. The rotor seals the gas path and controls the gap by grinding the honeycomb, so it should have a good balance, and the coating is not allowed to be unevenly worn or dropped. At present, the hard sealing coating applied to the outer ring of the low-pressure turbine rotor of a Pratt & Whitney engine is PWA53-37/11 (Ni ₅ Al+Al ₂ O ₃ 3TiO ₂ ) composite coating, but there is no such coating in China. Coating approval, technically no machining experience. The main technical difficulties in the coating preparation process are: the cross-section of the tip of the grate tooth is only about 0.5 mm (as shown in Figure 1 and Table 1), and the thickness of the coating on the side of the grate tooth needs to be accurately controlled in 5 sections within the range of 5 mm (0.05 mm to 0.1mm), and both sides of the grate teeth must be sprayed and formed at one time, so the process control is extremely difficult.

Table 1 Coating Size Requirements

Contents of the invention

In view of the above problems, the object of the present invention is to provide a method for controlling the thermal spraying of the knife-edge grate coating with a non-uniform thickness.

In order to achieve the above object, the thermal spray forming control method of the knife-edge grate coating of non-uniform thickness provided by the invention comprises the following steps carried out in order:

(a) Helium is used as the main gas, and argon is used as the powder feeding gas and auxiliary gas;

(b) During the spraying process, the helium pressure is 60psi, the argon pressure is 40psi, the argon pressure is 120psi, the spraying distance is 75mm, and the spraying speed is 350mm/s;

(c) The number of times of spraying is 5 times.

The optimal θ angle of the described spraying edge grate is 40°.

The walking path of the spray gun is selected in the way of depositing the coating at the same time in one cycle on the upper and lower sides.

Advantages of the present invention:

(1) According to the configuration characteristics of the grate tooth spraying part, the control method of the plasma spraying knife edge grate tooth thickness is determined.

(2) By optimizing the walking path of the spray gun, the non-smooth transition problem of the coating on the top of the grate teeth (AK) is solved.

Description of drawings

Figure 1 is a map of the coating distribution.

Figure 2 is a schematic diagram of various angles of the manipulator.

Fig. 3 Schematic diagram of various angles of another posture of the manipulator.

Figure 4 is a photo of the accumulated coating on the top of the grate sample (AK) when θ = 20°.

Figure 5 is a photo of the accumulated coating on the top of the grate sample (AK) when θ = 30°.

Figure 6 is a photo of the accumulated coating on the top of the grate sample (AK) when θ=40°.

Figure 7(a) and Figure 7(b) are the non-smooth transition photos of the coating on the top of the grate tooth, respectively.

detailed description

(1) Control of spraying angle

The following describes the angle control method in the ABB2400 six-axis manipulator. The schematic diagram of each angle of the manipulator is shown in Figure 2.

θ—the angle between the spray gun flame and the horizontal plane

θ ₃ ——The angle between the 3# axis of the manipulator and the horizontal plane (the display value of the manipulator)

θ ₅ ——The angle between the 5# axis of the manipulator and the extension line of the 3# axis (the display value of the manipulator)

It can be seen from the schematic diagram:

θ=90°-δ (1)

δ＝180°-(θ ₃ +θ ₅ ) (2)

Equation 3 is deduced from Equation 1 and Equation 2:

θ＝(θ ₃ +θ ₅ )-90° (3)

When the jet of the spray gun is below the workpiece, the schematic diagram of the θ angle is shown in Figure 3:

It can be seen from the above figure

θ=δ-θ ₃ (4)

δ＝90°-θ ₅ (5)

Formula 6 can be derived from formula 4 and formula 5

θ＝90°-(θ ₃ +θ ₅ ) (6)

After the above analysis, it can be concluded that the θ angle (the angle between the spray gun flame and the horizontal plane) is only related to θ ₃ (the rotation angle of the 3-axis display of the manipulator), and θ ₅ (the rotation angle of the 5-axis display of the manipulator), and with the angle The positive and negative changes of , the relational expression also changes.

(2) Design of spraying angle

According to formula 3 and formula 6, the design and precise control of the spray angle can be realized.

a The angle of the spray gun is 20° from the horizontal plane, so when the spray gun prepares the upper surface of the grate teeth, θ ₃ +θ ₅ =110°; when the spray gun prepares the lower surface of the grate teeth, θ ₃ +θ ₅ =70°;

b The angle of the spray gun is 30° from the horizontal plane, so when the spray gun prepares the upper surface of the grate teeth, θ ₃ +θ ₅ =120°; when the spray gun prepares the lower surface of the grate teeth, θ ₃ +θ ₅ =60°;

c The angle of the spray gun is 40° to the horizontal plane, so when the spray gun prepares the upper surface of the grate teeth, θ ₃ +θ ₅ =130°; when the spray gun prepares the lower surface of the grate teeth, θ ₃ +θ ₅ =50°.

(3) Optimization of spray gun walking path

The walking path of the six-axis manipulator is designed as follows:

a coating is deposited on both sides separately;

b One cycle on the upper and lower sides to simultaneously deposit the coating.

(4) Coating forming quality inspection

Metallographic samples were prepared to test the forming quality of the knife-edge grate coating.

In order to verify the effect of the inventive method, the inventor has carried out following experiment:

As shown in Figure 4, when θ = 20°, thicker coatings were deposited on the top (AK) of the grate sample, but no or little coating was deposited on the side (AL). The layer is mushroom-shaped, which makes the coating lose its role in protecting the AL area, so this angle is not advisable.

As shown in Figure 5, when θ = 30°, the coating on the top (AK) of the grate sample is relatively uniform, but the side (AL) has obvious waves, which is a common type of coating when the spraying angle is too small Morphology, which cannot guarantee the continuity and uniformity of the coating.

As shown in Figure 6, when θ=40°, the coating on the top (AK) and side (AL) of the grate sample is relatively uniform, and the coating transitions smoothly at AK. protected.

Since the coatings on both sides of the grate are prepared separately, the layer prepared later always overlaps the layer prepared earlier, which makes the top coating of the grate non-smooth transition (Fig. 7a). Redesign the walking path of the spray gun and the operation mode of the turntable. The turntable rotates at a certain speed, the spray gun moves up and down, and the coating is prepared on both sides of the grate teeth at the same time through the turning of the spray gun. The overlap of the coating on the top of the grate teeth was eliminated after the new spraying method (Fig. 7b).

Claims (3)

1. a thermal spraying forming control method of the knife edge grate tooth coating of non-uniform thickness, it is characterized in that: described control method comprises the following steps of carrying out in order: (a) Helium is used as the main gas, and argon is used as the powder feeding gas and auxiliary gas; (b) During the spraying process, the helium pressure is 60psi, the argon pressure is 40psi, the argon pressure is 120psi, the spraying distance is 75mm, and the spraying speed is 350mm/s; (c) The number of times of spraying is 5 times. 2. The thermal spraying forming control method of the knife-edge grate coating of non-uniform thickness according to claim 1, characterized in that: the optimal θ angle of the spraying knife-edge grate is 40°. 3. The thermal spray forming control method of the knife-edge grate coating with non-uniform thickness according to claim 1, characterized in that: the walking path of the spray gun selects the mode of depositing the coating at the same time in one cycle on the upper and lower sides.