JPH10286684A - Build-up method with laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method most suitable for mass-production, by which a fault of a build-up layer as well as a fault on the boundary face between a build-up layer and a base metal are dissolved, mutual bonding state of both metal is attendantly improved and generation of crack on the build-up layer is prevented. SOLUTION: In a build-up method with a laser beam that the surface of a base metal 1 composed of an aluminum base alloy is irradiated with a laser beam 9 while a copper alloy powder 7 is thrown, the copper alloy powder 7 is molten and a build-up layer 3 is formed, the relative moving velocity S [m/min] of the laser beam against the base metal 1 is set as 0.4<=S<=0.9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cladding method using a laser beam for irradiating a laser beam while pouring another metal material onto the surface of a metal base material and melting the other metal material to form a cladding layer. .

[0002]

2. Description of the Related Art A technique of irradiating a laser beam to form a build-up layer of another metal material on a metal base material is applied to, for example, a valve seat portion of a cylinder head of an automobile engine. FIG. 3 is a cross-sectional view of the vicinity of the valve seat portion 103 in the cylinder head 101, and an opening end 105a of the intake (exhaust) port 105 that opens to the combustion chamber side.
Is opened and closed by an intake (exhaust) valve 107, and an umbrella portion 107 a of the intake (exhaust) valve 107 can be in close contact with a seat surface 103 a of the valve seat portion 103.

Since the valve seat portion is under severe conditions such as repeated contact of the valve and exposure to high temperature during operation of the engine, the cylinder head is made of an aluminum alloy from the viewpoint of weight reduction. in case of,
There is a possibility that abrasion or erosion may occur. Therefore, the above-mentioned problem is solved by forming a build-up layer of another metal material having high heat resistance and abrasion resistance. After the build-up layer is formed, the valve seat surface is formed by machining.

[0004] The technique of overlaying other metal materials is different from the conventional technique of press-fitting a valve seat material made of cast iron or iron-based sintered material into a recess formed in a valve seat portion. Since the degree of adhesion between the main body (metal base material) and the build-up layer serving as the valve seat material is high, the thermal conductivity between the two is good, and the thermal load on the valve seat and the valve is reduced. As a result, it is possible to improve the durability and the output performance of the engine.

In the cladding method using a laser beam, there is no defect in the cladding layer constituting the valve seat material, and particularly, there is no defect in the interface between the cladding layer and the metal base material, and both are completely welded. Although it is desirable, in practical metals such as the cylinder head material described above, it is extremely difficult to completely eliminate the above-mentioned defects, and in fact, it is unavoidable that some unwelded portion exists at the interface. . This is because the cylinder head material manufactured by the LPDC (Low Pressure Die Casting) method, which is a normal mass production method, has some holes in the metal base material, and these holes exist at the interface. It is generated from. In addition, the holes in the metal base material enter into the build-up layer in a molten state when the metal base material heated by the other metal material melted by the laser beam irradiation is re-melted, and this enters the valve seat. When reaching the surface of the build-up layer which becomes a surface, a problem that the build-up layer is exposed by solidification and becomes a defective product also occurs.

For this reason, conventionally, defects such as vacancies on the surface of the metal base material have been crushed in advance by a rolling roll or the like to make them substantially free of defects (Japanese Patent Laid-Open No. 2-1961).
No. 17), and the method of casting the metal base material is changed to another method in order to reduce the number of holes in the metal base material.

[0007]

However, in any of the above methods, the former requires rolling with a rolling roll, while the latter requires an increase in the number of working steps, and is particularly costly in mass production. It is not suitable for practical use due to high cost. In the overlay method using a laser beam, when the amount of melting of the metal base material becomes excessive due to the irradiation of the laser beam, the metal base material enters the molten build-up layer and cracks occur in the solidified build-up layer. Cause.

[0008] In view of the above, the present invention is intended to improve the welded state of both layers by eliminating defects of the build-up layer and defects at the interface between the build-up layer and the metal base material, while being optimized for mass production. It is intended to prevent the occurrence of cracks in the build-up layer.

[0009]

Means for Solving the Problems To achieve the above object, the present invention firstly irradiates a laser beam while charging another metal material onto the surface of a metal base material to melt the other metal material. In the cladding method using a laser beam for forming a cladding layer, a cladding operation is performed by setting a relative moving speed S [m / min] of the laser beam to the metal base material as 0.4 ≦ S ≦ 3.0. There are things.

When the relative moving speed S [m / min] of the laser beam with respect to the metal base material is S <0.4, the heat input to the metal base material becomes too large and the melting amount of the metal base material increases. In addition, a large amount of the metal base material is mixed into the other metal material in the molten state, and cracks occur in the build-up layer during solidification. On the other hand, 3.0 <S
In such a case, the heat input to the metal base material is insufficient, so that other metal materials cannot be melted and the overlaying operation itself cannot be performed. For this reason, by setting the speed S to 0.4 ≦ S ≦ 3.0, it is possible to perform the overlaying work as desired while preventing the occurrence of cracks.

Secondly, in the cladding method using a laser beam for irradiating a laser beam while pouring another metal material onto the surface of the metal base material and melting the other metal material to form a cladding layer, And the relative moving speed S [m / min] with respect to the metal base material is set to 0.3 ≦ S ≦ 0.9 to perform the overlaying operation.

When the relative moving speed S [m / min] of the laser beam with respect to the metal base material is S <0.3, the heat input to the metal base material becomes excessive and the molten portion of the metal base material becomes large. ,
The amount of vacancies existing in the metal base material moving into the build-up layer in the molten state increases, and the amount of vacancies present at the interface between the metal base material and the build-up layer also increases, resulting in unwelding. Part occurs. On the other hand, when 0.9 <S, solidification of the build-up layer ends before the holes in the metal base material pass through the molten build-up layer, and the holes are trapped in the build-up layer. Voids are also exposed on the surface of the build-up layer, causing quality deterioration.
For this reason, by setting the speed S to 0.3 ≦ S ≦ 0.9, the amount of holes moving from the inside of the metal base material to the build-up layer side is reduced, and the space generated from inside the metal base material is reduced. The holes pass through the build-up layer before solidification of the build-up layer, thereby eliminating defects in the build-up layer and defects at the interface between the build-up layer and the metal base material.

[0013] Third, in a cladding method using a laser beam for irradiating a laser beam while pouring another metal material onto the surface of the metal base material and melting the other metal material to form a cladding layer, And the relative moving speed S [m / min] with respect to the metal base material is set to 0.4 ≦ S ≦ 0.9 to perform the overlaying operation.

According to the above-mentioned overlay method, cracks are generated in the overlay layer due to excessive heat input to the metal base material, and
It is possible to avoid an increase in the number of holes generated from inside the metal base material, and to prevent the build-up operation due to insufficient heat input and to prevent the holes generated in the metal base material from remaining in the build-up layer.

Fourth, a laser output of 3.0 to 4.5 kW,
The buildup operation is performed with the supply amount of the other metal material being 30 to 45 g / min.

FIG. 1 shows the relative movement speed S of the laser beam when the laser output is 4.0 kW and the supply amount of the copper alloy as another metal material is 40 g / min. Situation (for 10 workpieces, the case where at least one workpiece has cracked is indicated by "x", other cases are indicated by "o") and, among the 10 workpieces,
The table shows the number of workpieces generated on the surface of the build-up layer even if at least one hole having a diameter of 0.3 mm or more is provided.

According to this, when the moving speed S is 0.2 or less, a cracked work exists, and when the moving speed S is 0.3 or more, no crack occurs in all the works. Further, when the moving speed S is in the range of 0.1 to 0.8, the number of workpieces having even one void is “0”, and at 0.9, the number of workpieces having voids is “1”. In the following, 1.0 is "2", 1.1 is "5", and 1.2 is "6".

As for the cracks, those that have occurred cannot be used, so that the lower limit of the moving speed S is set at 0.
In the meantime, as for the pores, the pores generated on the surface of the build-up layer in the inspection stage after the production are shaken off, and the upper limit of the moving speed S is set to “1” where the number of generated pores is the minimum. 0.9. This makes it possible to avoid the occurrence of cracks in the build-up layer and also to prevent the formation of voids on the surface of the build-up layer.

The upper and lower limits of the laser output are set to 3.0 kW and 4.5 kW, and the upper and lower limits of the supply amount of the other metal material are set to 30 g / min and 45 g / min, respectively. From the results in FIG. 1 described above in which the supply amount of the other metal material was set to 40 g / min, when the laser output and the supply amount of the other metal material were set to values outside the above ranges, the excess and deficiency of the heat input amount and other factors Poor melting of metal material may occur,
This is because cracks are generated and the amount of pores remaining in the buildup layer is increased.

Therefore, the moving speed S is set to 0.3 ≦ S ≦
By setting 0.9, the laser output is set to 3.0 to 4.5 kW, and the supply amount of other metal materials is set to 30 to 40 g / min, thereby preventing cracks and forming holes in the overlay. The residual amount of the metal is reliably reduced, and the
Defects at the interface between the build-up layer and the metal base material are reliably eliminated. Thereby, the welded state between the metal base material and the build-up layer is also improved.

Fifth, the metal base material is an aluminum alloy that constitutes a valve seat portion in a cylinder head of an engine.

The valve seat portion of the cylinder head lightened by an aluminum alloy is made of a copper alloy having high heat resistance and abrasion resistance, which is free from cracks and defects and has a good welded state to a metal base material. When the engine is in operation, the build-up layer is formed, and the heat of the build-up layer constituting the valve seat surface is easily transmitted to the cylinder head body side, and the heat load on the valve seat portion and the valve is reduced, and the durability is improved. It is expected that the output performance of the engine will be improved.

[0023]

According to the first aspect of the present invention, the relative movement speed S [m / min] of the laser beam for irradiating the other metal material put on the metal base material with respect to the metal base material is set to 0.4 ≦ S ≦
By setting the value to 3.0, which is suitable for mass production, it is possible to perform the build-up work as desired while preventing the occurrence of cracks in the build-up layer.

According to the second aspect of the present invention, the relative movement speed S [m / min] of the laser beam for irradiating the other metal material injected onto the metal base material with respect to the metal base material is set to 0.3 ≦ S ≦ 0.
9, the amount of vacancies generated from inside the metal base material and moving toward the build-up layer in the molten state is reduced, and the vacancies generated from within the metal base material are reduced by the method suitable for mass production. Before the solidification of the build-up layer, it passes through the build-up layer in the molten state, thereby eliminating defects in the build-up layer and defects at the interface between the build-up layer and the metal base material and preventing the occurrence of unwelded portions. be able to.

According to the third invention, the relative movement speed S [m / min] of the laser beam for irradiating the other metal material put on the metal base material with respect to the metal base material is set to 0.4 ≦ S ≦ 0.
With a method suitable for mass production, which is set to 9, it is possible to avoid the occurrence of cracks in the build-up layer due to excessive heat input to the metal base material and the increase in the number of vacancies generated from within the metal base material, and the insufficient heat input. This makes it possible to prevent the build-up operation from being performed and the voids generated in the metal base material from remaining in the build-up layer.

According to the fourth aspect, the laser output is set to 3.0.
Up to 4.5 kW, the supply amount of other metal materials is 30 to 45 g / min, and a method suitable for mass production ensures prevention of cracks and reduction of the residual amount of pores in the overlay. Defects in the build-up layer and defects at the interface between the build-up layer and the metal base material can be reliably eliminated, and the welded state between the metal base material and the build-up layer can be improved.

According to the fifth aspect of the present invention, the valve seat portion of the cylinder head lightened by the aluminum alloy is made of a copper alloy having high heat resistance and abrasion resistance, has no cracks or defects, and is welded to the metal base material. A high quality build-up layer is also formed, and when the engine is running, the heat of the build-up layer forming the valve seat surface is easily transmitted to the cylinder head body side, and the heat load of the valve seat portion and the valve is reduced. It is expected that the durability will be improved and the output performance of the engine will be improved.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a method for building up with a laser beam according to an embodiment of the present invention. Here, it is assumed that the build-up layer 3 is formed on the valve seat portion of the cylinder head of the engine which is the metal base material 1. The cylinder head is an aluminum-based alloy (JIS: AC2A material) manufactured by the above-described LPDC method,
As another metal material constituting the cladding layer 3, a copper alloy (N
i: 15.5%, Co: 14.1%, Al: 0.91
%, V: 1.58%, Nb-1.84%, Si: 2.7
8%, with the balance being Cu).

The above-mentioned copper alloy powder 7 is supplied onto the metal base material 1 from the powder supply nozzle 5 and the supplied copper alloy powder on the metal base material 1 is irradiated with a laser beam 9. As a result, the copper alloy powder is melted to form the liquid phase portion 3a, and the liquid phase portion 3a solidifies to form the build-up layer 3. At the time of laser beam irradiation, the laser beam 9 and the powder supply nozzle 5 are fixed without moving, and the cylinder head itself is rotated around the central axis of the valve seat to build up the entire circumference of the valve seat. A layer will be formed.

The processing conditions are as follows.

Laser beam mode: ring mode Laser output: 4.0 kW Relative moving speed of laser beam with respect to metal base material: 0.6
m / min Copper alloy powder supply: 40 g / min Inclination angle θ of powder supply nozzle with respect to metal base material surface: 7
0 ° Inner diameter (diameter) of the powder supply nozzle: 3 mm Standoff (L): 10 mm When the overlaying was performed under the conditions of 10 mm or more, cracks occurred in the overlay 3 due to excessive heat input to the metal base material 1. In addition to increasing the number of holes generated from inside the metal base material 1 and moving to the build-up layer 3 side, the build-up work becomes impossible due to insufficient heat input and the holes generated in the metal base material 1 Residuals in the build-up layer 3 were avoided, and defects in the build-up layer 3 and defects at the interface between the build-up layer 3 and the metal base material 1 were reliably eliminated. As a result, the welded state between the metal base material 1 and the build-up layer 3 is also improved, and the heat of the build-up layer 3 forming the valve seat surface is easily transmitted to the cylinder head main body side, which is the metal base material 1. In addition, the heat load on the valve seat portion and the valve is reduced, so that the durability and the output of the engine can be improved.

Since the cylinder head constituting the above-mentioned metal base material 1 is manufactured by the LPDC method suitable for mass production, no complicated work process is required, and the metal base material is different from the conventional metal base material. There is no increase in the number of working steps such as rolling the surface, and it can be said that this is the most suitable method for mass production.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing, in a table, the state of occurrence of cracks and the number of vacancy-generated works with respect to the relative moving speed of a laser beam in the laser beam overlay method of the present invention.

FIG. 2 is an explanatory view showing a specific working form of the laser beam overlay method of the present invention.

FIG. 3 is a cross-sectional view of the vicinity of a valve seat in a cylinder head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal base material 3 Overlay layer 7 Copper alloy powder (other metal materials) 9 Laser beam

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02F 1/24 F02F 1/24 S

Claims (5)

[Claims] 1. A cladding method using a laser beam for irradiating a laser beam while pouring another metal material onto the surface of a metal base material and melting the other metal material to form a cladding layer. A cladding method using a laser beam, wherein a cladding operation is performed by setting a relative moving speed S [m / min] with respect to a base material to 0.4 ≦ S ≦ 3.0. 2. A cladding method using a laser beam for irradiating a laser beam while pouring another metal material onto a surface of a metal base material and fusing the other metal material to form a cladding layer. A cladding method using a laser beam, wherein a cladding operation is performed with a relative movement speed S [m / min] relative to a base material being 0.3 ≦ S ≦ 0.9. 3. The cladding operation according to claim 1, wherein the relative movement speed S [m / min] of the laser beam with respect to the metal base material is set to 0.4 ≦ S ≦ 0.9. Laser beam build-up method. 4. The method according to claim 3, wherein the laser beam output is 3.0 to 4.5 kW and the supply amount of the other metal material is 30 to 45 g / min. . 5. The laser according to claim 1, wherein the metal base material is an aluminum-based alloy constituting a valve seat portion in a cylinder head of the engine, and the other metal material is a copper alloy. Overlay method by beam.