JPS63256274A - Welding method for powder build-up - Google Patents

Abstract

PURPOSE:To uniformize a bead height by supplying powder while rotating material to be built-up and further, weaving a plasma torch to maintain a current and the voltage at fixed values while rotating the material to be built-up and weaving the torch after the supply of the powder is stopped. CONSTITUTION:A plasma arc 20 is generated between the material 1 to be built-up and an electrode 11 and the powder 19 for the build-up welding is supplied in the plasma arc 20 to weld the bottom 2 of the material 1 to be built-up. At this time, the welding is performed while rotating the material 1 to be built-up and further, weaving the plasma torch 10. After the supply of the powder 19 for the build-up welding is stopped, the current and voltage are maintained at the fixed values (about 140A and about 35V) while operating the material 1 to be built-up and the plasma torch in the same way mentioned above to form a build-up welded zone 4. By this method, molten metal is prevented from swelling and a bead with the uniform height is obtained and the completely deposited build-up welding is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of build-up welding using powder, and more specifically to a method of build-up welding using plasma powder build-up welding.

The present invention relates to a powder build-up welding method that is applied to build-up welding on the bottom of a combustion chamber of a combadge eye insert for a diesel engine, and build-up welding on the bottom of a part forming a ground circuit.

(Prior art and problems) In conventional build-up welding, the welding to the material to be built-up is complete, the composition of the build-up weld metal is close to the build-up phase component before build-up welding, and the build-up welding area Although it is required that the bead shape be good and the yield of overlay material be high, the conventional wire and rod overlay method is not suitable for overlaying the bottom of a concave part. In particular, it is almost impossible to build up the bottom of a part with a small diameter and deep hole.

Also, when welding on the bottom of a concave part, if the welding time is short, the welding will not fully blend into the material to be welded, leaving an unwelded area, and if the welding time is not long enough, the temperature of the wall will gradually rise and the welding will become difficult. As a result, as shown in FIG. 6, the built-up weld metal rose along the wall of the concave part and the center became depressed, making it impossible to obtain a sufficient bead height or causing weld penetration.

For this build-up welding, attempts are underway to adopt plasma build-up welding using powder, but in this method, build-up welding powder is supplied into a plasma arc, and the powder reaches the material to be built up. During the welding process, the material is heated and melted by a plasma arc, and the material to be built-up is also heated and welded on the surface. However, in the case of build-up welding on the bottom of a concave part, a plasma torch is used to weld the bottom of the concave part. Because the distance must be long, the energy of the plasma arc may not reach the bottom sufficiently, resulting in non-welding.

Alternatively, since a fixed part is heated for a long time, there is a problem that the repeated shape of the welded parts is not fixed.

(Means for solving the problems) The present invention has been made by focusing on the above-mentioned problems.
It is an object of the present invention to provide a powder build-up welding method in which a good bead shape can be obtained by welding the bottom of a concave part, which is a material to be built-up, using powder.

The present invention differs from the conventional shape of the bottom 2 of the welding material 1 shown in FIG.
has a predetermined build-up shape, and is provided with a stepped portion 3 having a diameter D2 larger than the predetermined build-up diameter D□ at the position of the required build-up height H, and when heated by a plasma arc, the stepped portion 3 The lower part is heated and the temperature above the stepped part 3 drops rapidly, which causes poor compatibility with the overlay material and prevents the molten metal from rising upwards. This prevents the center from being depressed, resulting in a good shape and sufficient thickness. It is characterized by the ability to obtain a high bead height.

Furthermore, in the conventional welding method, as shown in Table 1, welding current and powder feeding are carried out using almost the same operations, but in the present invention, as shown in Table 2, the current is increased together with powder feeding, and local heating is performed. To avoid this, the material to be overlaid is rotated and the plasma torch is weaved. Once the overlay material is pooled at the bottom of the concave part and the powder feeding is stopped, the welding current is not further lowered, or in some cases, the current value is lowered after the powder runs out, and the overlay material and the material to be welded are sufficiently welded. This is a powder build-up welding method that blends the materials and completely welds them, with almost no weld penetration.

(Example) Examples of the present invention will be described together with comparative examples using conventional methods.

Using the plasma torch 10 shown in FIG. 3, a combadge 1-inch beam welding material 1 for a diesel engine is placed on a jig 8 placed on a positioner 9 as shown in FIG. Set.

Overlay welding was performed on the bottom of the combadge insert shown in FIG. 1.

Table 1 Table 2 111111 Depending on the situation, reduce the current and voltage values after the powder runs out.

Welding conditions Plasma gas: 2.5Q/win Shielding gas: 15Q/m1n Chiaria gas: 5p/1n Weaving: Width 12mm, 1 reciprocation 1 second Torch center: 4mm from the center of the overlay material Posi-shiminer: 2
5r,p,m Powder supply rate: 0.3g/see Current: 140A As a result, as shown in Figure 6, in the conventional method without steps, the molten metal rises up along the wall and reaches the center. As shown in Fig. 5, the method of the present invention, in which the predetermined build-up thickness was not achieved due to the depression, but one step was provided.
The effect of the step according to the present invention was confirmed because the shape of the bead was good and the thickness was also uniform and a predetermined build-up thickness was obtained.

Next, with respect to the stepped bottom part of the overlay material of the present invention using the overlay material and overlay material shown below.

Overlay welding was performed under the conditions described above, with different welding conditions depending on the presence or absence of rotation of the overlay material, the presence or absence of weaving, and the position of the plasma torch.

Welding material: 5US403, 304, 430 Welding material: Hi-Tei C, Stellite 21, 28, 188 Welding results.

Under welding condition (2), as shown in FIG. 7(B), welded portions 6 are formed at the ends and unwelded portions 5 are formed at the center.

Under welding condition (3), as shown in FIG. 7(C), unwelded portions 5 occur at the ends and welded portions 6 occur at the center.

Welding condition (4) is similar to welding condition (3) as shown in Fig. 7 (C
), there are unwelded parts 5 at the ends and welded parts 6 at the center.

The shape of the bead of the built-up part obtained by the present invention under welding condition (1) was obtained by rotating the welding material and weaving the plasma torch, as shown in Fig. 7(A). Since heating was avoided, complete welding was achieved, and there was no occurrence of unweldedness or weld penetration, resulting in very excellent build-up welding.

From the above results, the effects of rotation and weaving of the overlay material according to the present invention were confirmed.

An example of a plasma torch used for powder overlay welding of the present invention is explained based on FIG. 3. Plasma torch 10
The inner cylinder 12 is arranged concentrically around the electrode 11 connected to the cathode side (-) of the power source 22, and a cooling water passage 13 is provided in the inner cylinder 12 between the electrode 11 and the inner cylinder 12. A plasma gas flow path 14 is formed between them, and a plasma arc nozzle 15 is formed at the lower end of the inner cylinder 12. An outer cylinder 16 is disposed on the outer periphery of the inner cylinder 12, and a plasma arc jetting nozzle 17 is formed at the lower end of the outer cylinder 16.

A powder supply path 18 is formed between the inner cylinder 12 and the outer cylinder 16, and powder 19 is supplied into the plasma arc 20 together with a powder supply gas from a powder supply device (not shown). A cooling water passage 22 is also formed in the outer cylinder 16 and the nozzle portion, so that the shielding gas from the shielding gas supply passage 21 uniformly shields the plasma arc.

For powder build-up welding, connect the cathode side (-) of the power source 23 to the electrode 1.
1 and the anode side (+) is connected to the material to be overlaid, and a plasma arc 20 is generated between the electrode 11 and the material to be overlayed.
At the same time, the overlay welding powder 19 is supplied into the plasma arc 20 by the powder supply gas, and is melted and welded on the surface of the overlay material 1. In addition, the plasma arc and the overlay welding area are covered with shielding gas and isolated from the outside air.

(Effects) As a plasma powder build-up welding method for a bottom part of a concave build-up material according to the present invention, a step is provided in advance at the bottom build-up part, the build-up material is rotated, and a plasma torch is weaved. By doing so, you can prevent the molten metal from rising and obtain a bead of uniform height.
In addition, the effect of avoiding local heating and achieving excellent overlay welding with complete welding is remarkable.

[Brief explanation of the drawing]

Fig. 1 A cross-sectional view showing the shape of the welding material according to the present invention Fig. 2 A cross-sectional view showing the shape of the conventional welding material Fig. 3
Figure 4 is a cross-sectional view of the main parts of the plasma torch used for the main foaming. Figure 5 is an explanatory diagram showing the set state of the overlay material.
FIG. 6 shows the shape of a bead according to the present invention. FIG. 7 shows the shape of a bead according to the conventional method. FIG. ) (B) Bead shape according to welding condition (2) (C) Bead shape according to welding condition (3) and welding condition (4) 1: Overlay material 2: Bottom 3: Step 4: Overlay welding Part 5: Unwelded part
6: Welding part 8: Positioner 9: Jig 10: Plasma torch

Claims (1)

[Claims] 1. Overlay welding powder (1) in the plasma arc (20)
9) is supplied, and while the powder (19) is heated and melted by the plasma arc (20) until it reaches the material to be welded (1), the material to be welded to be welded (1) is also heated. In plasma powder overlay welding where welding is carried out on the surface, when the overlay material (1) is powder overlay welded to the bottom (2) of a concave part, the overlay material (1) is rotated and then the plasma torch is applied. Powder is supplied while weaving (10), and even after the powder supply is stopped, the current and voltage are maintained at a predetermined value while rotating the overlay material (1) and weaving the plasma torch (10). A powder overlay welding method characterized by: 2. The bottom of the concave part (2) which is the filler material (1)
) is provided with a stepped portion 3 having a predetermined build-up shape and having a diameter D_2 larger than the diameter D_1 of the predetermined build-up at a position of the required build-up height H. Powder build-up welding method.