JP2000015438A - Pretreatment method for build-up welding of casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable no-defect build-up welding by eliminating a casting defect in a build-up welding section of a casting beforehand. SOLUTION: When conducting build-up welding to a casting 1, a build-up welding section 1W of the casting is softened by generating friction heat with rotating a rod 2 to enable plastic flow, further by pressurizing plastic flow enabled section and imparting reduction, a casting defect is eliminated beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to overlay welding on a cast product, which is suitable for performing a pretreatment for removing a casting defect in a weld portion of the cast product. It relates to a pre-processing method.

[0002]

2. Description of the Related Art A cast product is easier to form into a desired shape than a forged product, and is particularly advantageous when it has a hollow portion. Further, there is little disadvantage that the material yield is greatly reduced as in the case of a cut product.

[0003]

However, castings sometimes have so-called casting defects, such as formation of cavities or pores and the occurrence of stagnation.

[0004] When the build-up welding is directly performed on a casting having such a casting defect,
For example, when air bubbles are formed in the inside, the air bubbles expand due to the heat generated during the build-up welding, so that a build-up defect due to the casting defect may occur in the build-up welding portion. There was a point.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made in order to eliminate casting defects in a welded portion of a cast product in advance, and then to perform overlay welding. The purpose is to prevent the occurrence of defects.

[0006]

According to a first aspect of the present invention, there is provided a method for pretreatment of overlay welding on a cast product, the method comprising the steps of: By generating frictional heat by the rotation of the rod at the welding site and softening it, plastic flow is possible, and plastic flowable parts are pressurized and reduction is added to eliminate casting defects in advance. .

According to an embodiment of the pretreatment method for overlay welding on a cast product according to the present invention, an annular overlay welding around the opening is performed. By using a rod having a protruding guide portion facing the inside from the opening, frictional heat is generated and softened, thereby enabling plastic flow around the opening.

[0008] Similarly, in an embodiment of the method for pretreatment of overlay welding on a cast product according to the present invention, as described in claim 3, the overlay welding includes TIG, MIG, PPW,
The method can be selected from laser welding methods.

[0009] Similarly, in an embodiment of the method for preparing a weld overlay on a cast product according to the present invention, the rod has a softening temperature higher than the softening temperature of the cast product. It is more desirable to use a material.

[0010] Similarly, in an embodiment of the method for pretreatment of overlay welding on a cast product according to the present invention, the cast product is made of an aluminum alloy, and the rod is made of stainless steel. Things.

[0011] Similarly, in an embodiment of the method for pretreatment of overlay welding on a cast product according to the present invention, the same rod is used for pressurizing the plastic flowable portion as described in claim 6. Can be made.

Similarly, in the embodiment of the method for pretreatment of overlay welding on a cast product according to the present invention, as described in claim 7, frictional heat generated by rotation of the rod and reduction by reduction of the pressure of the rod are reduced. The rod may be moved in the direction of the plane of the casting during the addition.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 show one embodiment of a method for pretreatment of overlay welding on a cast product according to the present invention. The procedure for performing the processing is shown.

In the present invention, when performing the pretreatment for the overlay welding portion 1W of the cast product 1 shown in FIG. 1, a solid material (or a material having a softening temperature higher than the softening temperature of the cast product 1) is used. Pipe 2), the rod 2 is rotated in the direction of arrow A in FIG.
As shown in FIG. 2, the plastic flowable state by softening caused friction heat by pressing at a pressure P ₁ in the overlay welding portion 1W of the casting 1 the rod 2.

[0015] Next, as shown in FIG. 3, by adding a reduction pressurizes the rod 2 at the pressure _{P 2} in the plastic flow moiety 1P, plastic flow moiety 1P for example, about 0.5~3mm The casting defect is eliminated by compressing with a pushing allowance and pressing a casting defect portion where a nest or a pore that may have been present in the overlay welding portion 1W is formed or a stagnation occurs. To improve the organization.

Thereafter, as shown in FIG. 4, a build-up weld 3 is formed on the build-up welded portion 1W on which the build-up structure improving layer 1R is formed to form a build-up layer 3 having no build-up defect.

In such overlay welding, TIG
(Tungsten Inert Gas), MIG
(Metal Electrode Inert Ga
s), PPW (Plasma Power Weld)
ing), laser, or other various welding methods.

When the plastic flowable portion 1P is pressurized, the same rod 2 is usually used.

If necessary, the rod 2 is moved in the direction of the surface of the casting 1 during frictional heating due to rotation of the rod 2 and addition of reduction by pressurization of the rod 2 so that an appropriate trajectory is formed. It is also possible to form the built-up structure improving layer 1R having a build-up.

FIG. 5 shows another embodiment of the present invention, in which a casting (for example, an engine cylinder head or the like) having an opening 1H such as an intake port or an exhaust port is provided.
1 shows a case where the valve seat is made of a build-up alloy in order to strengthen a valve seat serving as a seat for an intake valve or an exhaust valve.

As a pretreatment at the time of such overlay welding,
Using the rod 2 having the projecting guide 2G facing the inside from the opening 1H, the rod 2 is rotated in the direction of arrow A with the projecting guide 2G facing the inside of the opening 1H, and the opening 1H is opened. In the state of plastic flow by generating frictional heat and softening in the annular part around the
By applying pressure to the rod 2 in the direction of the arrow P, reduction is applied to the plastically flowable portion, and nests or pores that may have been present at the overlay welding site may be formed, and stagnation may occur. The structure is improved by eliminating the casting defect by compressing the part of the casting defect that has been made, improving the structure after that, performing the overlay welding in an annular shape, and then finishing, so that the valve with the defect-free overlay welding part Seat (valve seat).

[0022]

1 to 4 show a rod 2 made of austenitic stainless steel (SUS304) at a welded portion 1W of a cast product 1 made of an aluminum alloy (AC8A). While rotating at a rotational speed of about 1200 rpm in the direction of arrow A of FIG.
Pressurized under a pressure P _1, as shown in, after a plastically flowable state by softening causing frictional heating, the rod 2 pressure in the plastic flow moiety 1P as shown in FIG. 3 P ₂ The plastic flowable portion 1P is compressed with a press allowance of about 2 mm by applying pressure to reduce the casting defects by pressing the nests (or pores) existing at the overlay welding portion 1W. Was improved.

Thereafter, as shown in FIG. 4, the build-up layer 3 having no build-up defect is formed by performing plasma powder build-up welding on the build-up weld portion 1W where the build-up structure improving layer 1R is formed. Formed.

[0024]

According to the pretreatment method for overlay welding on a cast product according to the present invention, as described in claim 1, when performing overlay welding on a cast product, a portion of the overlay on the cast product is provided. Since the frictional heat generated by the rotation of the rod caused by the rotation caused the rod to soften and made it possible to flow plastically, the plastic flowable part was pressurized and reduction was added, so casting defects occurred at the overlay welding part of the cast product Even if it is, since this casting defect can be eliminated before overlay welding, it is extremely excellent that it is possible to prevent the occurrence of overlay welding defects when performing overlay welding. The effect is brought.

And, as described in claim 2,
When performing an annular build-up weld around the opening, frictional heat is generated and softened using a rod with a protruding guide facing the inside from the opening to allow plastic flow around the opening. Thus, an annular plastic flowable portion can be reliably formed without any positional displacement at the annular build-up welded portion, and reduction is added to this plastic flowable portion to eliminate casting defects. By doing so, a remarkably excellent effect that it is possible to obtain an annular build-up weld having no build-up defect is provided.

According to the third aspect of the present invention, the overlay welding is performed by selecting from the welding methods of TIG, MIG, PPW, and laser so that the overlay welding can be performed. A remarkably excellent effect is obtained in that it is possible to obtain a high quality weld overlay.

Further, as described in claim 4,
By making the rod of a material having a softening temperature higher than the softening temperature of the casting, a remarkably excellent effect that it is possible to favorably add reduction at the plastic flowable portion of the casting is achieved. Brought.

Further, as described in claim 5, the casting is made of an aluminum alloy, and the rod is made of stainless steel to prevent the casting alloy from sticking to the rod. Thus, for example, a remarkably excellent effect that defect-free build-up welding can be performed on a cylinder head made of an aluminum alloy is provided.

Furthermore, by using the same rod for pressurizing the plastic flowable portion as described in claim 6, the formation of the plastic flowable portion due to frictional heating and the plastic flowable portion can be achieved. Addition of reduction to parts can be performed easily, and
By forming the plastic flowable portion due to frictional heat and adding the reduction to this plastic flowable portion with separate rods, it becomes possible to select rod materials with suitable materials for each. Excellent effect is brought.

Further, as described in claim 7, the rod is moved in the surface direction of the casting while performing frictional heat generation by rotation of the rod and addition of reduction by pressurization of the rod. In this way, a structure-improving layer for overlay having a shape (or a locus) corresponding to the shape of a desired overlay weld portion is formed to form an overlay weld having a desired shape without overlay defects. This has a remarkably excellent effect of enabling

[Brief description of the drawings]

FIG. 1 is an explanatory view of a slope showing a state before a rod is brought into contact with a build-up welding portion of a cast product in one embodiment of a method for pre-treating a build-up weld to a cast product according to the present invention.

FIG. 2 is an explanatory view of a slope showing a state after frictional heat is generated after a rod is brought into contact with a build-up welding portion of a cast product in an embodiment of a method for pre-treating a build-up weld to a cast product according to the present invention. It is.

FIG. 3 is a cross-sectional view showing a situation after a reduction has been added to a plastic flowable portion formed at a build-up welding portion of a cast product in one embodiment of a method for pre-treating a build-up weld to a cast product according to the present invention. FIG.

FIG. 4 is an explanatory cross-sectional view showing a state after a buildup layer is formed at a buildup welding portion of a cast product in one embodiment of a method for pretreatment of overlay welding on a cast product according to the present invention.

FIG. 5 is an explanatory cross-sectional view showing another embodiment of the method for pretreatment of overlay welding on a cast product according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Cast product 1H Opening of cast product 1P Plastic flowable portion 1R Structure-improving layer for overlaying 1W Overlay welded portion of cast product 2 Rod 2G Projection guide portion of rod 3 Overlay layer

Claims (7)

[Claims] When performing overlay welding on a cast product, frictional heat is generated by the rotation of a rod at a build-up welding portion of the cast product to soften it, thereby enabling plastic flow and pressurizing the plastic flowable portion. A method for preparing a weld overlay on a cast product, characterized by adding reduction. 2. When performing an annular build-up welding around the opening, frictional heat is generated and softened by using a rod having a protruding guide portion facing inward from the opening, so as to be softened around the opening. The method for pretreatment of overlay welding on a cast product according to claim 1, wherein the method enables plastic flow. 3. The overlay welding includes TIG, MIG, PPW,
The method for pretreatment of overlay welding on a cast product according to claim 1 or 2, wherein the method is performed by selecting from laser welding methods. 4. The method of claim 1, wherein the rod is made of a material having a softening temperature higher than a softening temperature of the cast product. 5. The method according to claim 1, wherein the cast product is made of an aluminum alloy, and the rod is made of stainless steel. 6. The method according to claim 1, wherein the same rod is used for pressurizing the plastic flowable portion. 7. The casting according to claim 1, wherein the rod is moved in the plane direction of the casting while performing frictional heating by rotation of the rod and addition of reduction by pressing the rod. Overlay welding pretreatment method.