JP3613997B2 - Laser overlay method - Google Patents

Description

表１の結果から、加工点の上昇量Ａをクラッドビード１の高さＨに対して、 Ｈ／３≦Ａ≦２Ｈ／３ の関係とすることで、オーバーラップ部分３の先端部ないしその近傍には、欠肉やクラックなどの不具合が発生しないことが確認できた。
【００２７】
なお、本発明に係わるレ−ザ肉盛り方法の詳細な構成は、上記した実施例の構成に限定されるものではない。
【図面の簡単な説明】
【図１】本発明の一実施例によるレ−ザ肉盛り方法における加工点の上昇経路説明図（ａ）および形成されたクラッドビードのオーバーラップ部分を示す部分拡大説明図（ｂ）である。
【図２】従来のレ−ザ肉盛り方法における加工点の上昇経路説明図（ａ）および形成されたクラッドビードのオーバーラップ部分を示す部分拡大説明図（ｂ）である。
【符号の説明】
１ クラッドビード（肉盛り部）
２ バルブシート部（肉盛り領域）
３ オーバーラップ部分
１１ クラッドビードの始端
１２ クラッドビードの終端
Ａ 加工点の上昇量
Ｈ クラッドビード高さ
ＷＰ オーバーラップ開始点[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of laminating a laser used to form a coated metal bead (clad bead) on a valve seat portion of a cylinder head of an engine, for example.
[0002]
[Prior art]
As described above, for example, when a clad bead is formed in a valve seat portion of an engine cylinder head, a powdery copper-based build-up alloy material continuously supplied from a nozzle moving along the valve seat portion is used. On the other hand, a clad bead is formed by irradiating a laser beam, but in order to obtain a ring-shaped clad bead with a necessary amount of build-up, as shown in FIG. The overlap portion L1 is formed by overlapping the end Be of the clad bead Ba on the start end Bs of the clad bead Ba having a height h formed in the valve seat Va.
[0003]
Conventionally, when the overlap portion L1 is formed, as shown in FIG. 2A, the center line of the nozzle moved along the path r1 from the processing start end Ws and the irradiation center line of the laser beam intersect. The point is raised in the range of 0.8 h to 1.2 h along the path r2 set in accordance with the shape of the start end Bs of the cladding bead Ba at the overlap start point Wp, and then the processing end We along the path r3 To move to. (Japanese Patent Laid-Open No. 10-034360)
[0004]
[Problems to be solved by the invention]
However, in the prior art, since the machining point suddenly rises in the rising region after the overlap start point Wp, that is, the nozzle for supplying the overlaying alloy material rises rapidly, The drop rate of the alloy material changes, and the supply amount of the build-up alloy material to the processing point changes temporarily, so that the concave thin wall n1 and the relative heat input, particularly at the tip of the overlap portion L1. There is a problem that crack n2 due to excess may occur, and it has been a conventional problem to solve this problem.
[0005]
OBJECT OF THE INVENTION
The present invention has been made by paying attention to the above-described conventional problems. In the case where a build-up portion is formed on a base material by performing laser build-up processing, the end of the build-up portion is formed at the start end of the build-up portion. It is an object of the present invention to provide a laser embedding method capable of preventing defects such as lacking and cracks from occurring at the tip of the overlap portion when forming an overlap portion.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is directed to irradiating a laser beam to a powdery build-up material continuously supplied from a nozzle moving along a build-up region of the base material, and The method of laminating a laser is to build up the overlap portion by overlapping the end of the build-up portion with the start end of the build-up portion. The construction of this laser overlay method is characterized by the fact that the processing is performed while continuously raising the processing point where the center line of the nozzle supplying the laser beam and the irradiation center line of the laser beam intersect. This is a means for solving the above-described conventional problems.
[0007]
The laser build-up method according to claim 2 of the present invention is configured to raise the processing point at a constant speed.
[0008]
In the laser overlaying method according to claim 3 of the present invention, the amount of increase in the machining point from the start of machining until the machining point reaches the overlap start point is A, and the amount of increase in the intermediate portion of the overlaying portion is high. When the height is H, the increase amount A is in the range of H / 3 ≦ A ≦ 2H / 3.
[0009]
The laser build-up method according to claim 4 of the present invention is configured such that the supply of the build-up material and the irradiation of the laser beam are delayed and started with respect to the timing when the processing point starts to rise.
[0010]
[Effects of the Invention]
In the laser embedding method according to claim 1 of the present invention, the machining point does not rise rapidly at the overlap start point, that is, the nozzle rise speed is slow at the overlap start point, so that it falls by its own weight. The falling speed of the build-up material rarely changes, and as a result, the build-up material is stably supplied to the processing point, and an overlap portion free from defects such as lacking and cracks is formed. The Rukoto.
[0011]
In the laser embedding method according to claim 2 of the present invention, since the processing point rises at a constant speed from the machining start end, problems such as lacking and cracks occur as in the laser embedding method according to claim 1. In addition to the formation of an overlapped portion having no gap, a good built-up portion having a substantially uniform height is formed.
[0012]
In the laser build-up method according to claim 3 of the present invention, the amount of increase A of the machining point from the start of machining until the machining point reaches the overlap start point is 1/3 of the height H of the build-up portion. As described above, the probability of occurrence of cracks due to excessive heat input at the tip of the overlap portion is low, and the amount of increase A is 2/3 or less of the height H of the built-up portion. Therefore, the probability that an unwelded portion is generated at the front end portion of the overlap portion or in the vicinity thereof is low, and therefore, an overlap portion free from defects such as lacking and cracks is formed.
[0013]
In the laser embedding method according to claim 4 of the present invention, since the processing point starts to rise at a constant speed, the supply of the overlaying material and the irradiation of the laser beam are started. The acceleration generated at the start does not affect the supply of the build-up material and the irradiation of the laser beam, and the supply of the build-up material is made stable from the start of the substantial processing to the end of the processing. Become.
[0014]
【The invention's effect】
In the laser build-up method according to claim 1 of the present invention, since the above-described configuration is adopted, the supply amount of the build-up material at the overlap start point can be stabilized, and the tip portion of the overlap portion or its An extremely excellent effect is obtained that it is possible to prevent the occurrence of defects such as lacking or cracks in the vicinity.
[0015]
In the laser embedding method according to claim 2 of the present invention, since the machining point rises at a constant speed from the machining start end, it is possible to form a good embedding portion having a substantially uniform height, An extremely excellent effect is obtained that it is possible to form an overlap portion free from defects such as meat and cracks.
[0016]
In the laser embedding method according to claim 3 of the present invention, since it has the above-described configuration, the probability of occurrence of cracks at the tip of the overlap portion can be kept low, and the tip of the overlap portion. In addition, the probability of occurrence of an unwelded portion in the vicinity thereof can also be suppressed to a low level, and therefore, an extremely excellent effect is obtained that it is possible to form an overlap portion that is free from defects such as lacking or cracks.
[0017]
In the laser build-up method according to claim 4 of the present invention, since the above-described configuration is adopted, the acceleration generated at the start of raising the machining point is substantially the same amount that does not affect the supply of the build-up material and the irradiation of the laser beam. Thus, it is possible to achieve an extremely excellent effect that it is possible to realize a stable supply of the build-up material from the start of processing to the end of processing.
[0018]
【Example】
Hereinafter, the present invention will be described with reference to FIG.
[0019]
FIG. 1B shows a clad bead formed on a valve seat portion (building area) of a cylinder head (base material) of an engine by a laser building method according to an embodiment of the present invention. The clad bead 1 is formed by irradiating a laser beam to a powdery build-up material continuously supplied from a nozzle moving along a valve seat portion 2.
[0020]
In this case, in order to obtain a ring-shaped clad bead 1 in which a necessary amount of build-up is ensured, an overlap portion 3 is formed by overlapping a terminal end 12 on the start end 11 of the clad bead 1 and this overlap. When the portion 3 is formed, as shown in FIG. 1A, the center line of the nozzle that supplies the build-up material and the irradiation center line of the laser beam are set between the start of processing and the end of processing. The intersecting machining points are moved along the path R from the machining start end WS to the machining end WE, that is, the nozzle and the laser beam are raised at a constant speed.
[0021]
In this embodiment, when the amount of increase in the machining point from the start of machining until the machining point reaches the overlap start point WP is A, and the height at the intermediate portion of the clad bead 1 is H, the amount of increase A Is set so as to satisfy the relationship of H / 3 ≦ A ≦ 2H / 3 with respect to the height H of the clad bead 1, and in this embodiment, with respect to the timing when the machining point starts to rise. The supply of the overlay material and the irradiation of the laser beam are delayed and started.
[0022]
Therefore, in the laser build-up method according to this embodiment, since all the sections from the start of processing to the end of processing are set as the rising points of the processing points, the processing points rapidly increase at the overlap start point WP. In other words, the rising speed of the nozzle at the overlap start point WP does not increase, so that the falling speed of the build-up material falling by its own weight hardly changes, and the processing point is reduced. On the other hand, the build-up material is stably supplied, and as a result, the overlap portion 3 free from defects such as lacking and cracks is formed.
[0023]
Further, in the laser build-up method according to this embodiment, since the processing point rises from the processing start end WS at a constant speed, a good clad bead 1 having a substantially uniform height can be obtained and the processing can be performed. Since the rising amount A of the point is in a relationship of H / 3 ≦ A ≦ 2H / 3 with respect to the height H of the clad bead 1, there is a defect such as a lack of thickness or a crack at the tip of the overlap portion 3 or in the vicinity thereof. There is almost no possibility of it occurring.
[0024]
Further, in the above-described laser build-up method, after the processing point starts to rise at a constant speed, the supply of the build-up material and the irradiation of the laser beam are started. As a result, the supply of the build-up material does not extend to the supply of the build-up material and the irradiation of the laser beam. As a result, the supply of the build-up material is stably performed from the start to the end of the process. It will be.
[0025]
Therefore, when the cladding bead 1 is formed on the valve seat portion 2 of the cylinder head under the following processing conditions by the laser embedding method described above, from the start of processing until the processing point reaches the overlap start point WP. The amount A of increase in the processing point was changed in five ways, and the occurrence rate (%) of defects with respect to each increase amount A, the contents of the defects, and the presence or absence of lacking were examined. The results shown in Table 1 were obtained.
[0026]
Processing conditions Clad bead 1 height (H): 1.8 mm
Machining point output: 3.75 kW
Supply amount of overlaying material: 60 g / min
Processing speed: 0.8mm / min
Standoff: 22mm
[Table 1]

From the results shown in Table 1, the amount of increase A in the processing point is set to a relationship of H / 3 ≦ A ≦ 2H / 3 with respect to the height H of the cladding bead 1, so that the tip of the overlap portion 3 or the vicinity thereof It was confirmed that there were no defects such as cutouts and cracks.
[0027]
The detailed configuration of the laser overlay method according to the present invention is not limited to the configuration of the above-described embodiment.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram (a) of an ascending path of a machining point and a partially enlarged explanatory diagram (b) showing an overlap portion of a formed clad bead in a laser embedding method according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram (a) of a rising path of a processing point and a partially enlarged explanatory diagram (b) showing an overlapping portion of a clad bead formed in a conventional laser cladding method.
[Explanation of symbols]
1 Cladding bead
2 Valve seat (filling area)
3 Overlap portion 11 Cladding bead start 12 Cladding bead end A Machining point increase H Cladding bead height WP Overlap start point

Claims (4)

This is a laser build-up method in which a laser beam is irradiated to a powdery build-up material continuously supplied from a nozzle that moves along the build-up region of the base material to form a build-up portion on the base material. And
When forming the overlap part by overlapping the end of the build-up part on the start end of the build-up part,
From the start of processing to the end of processing, it is characterized by performing build-up processing while continuously raising the processing point where the center line of the nozzle that supplies the build-up material and the irradiation center line of the laser beam intersect Laser fill method to do. 2. The method of laminating a laser according to claim 1, wherein the processing point is raised at a constant speed. Assuming that the amount of increase in the machining point from the start of machining until the machining point reaches the overlap start point is A, and the height at the intermediate portion of the built-up portion is H, the amount of increase A is H / 3 ≦ A 3. The method of laminating a laser according to claim 2, which is in a range of ≦ 2H / 3. 4. The laser build-up method according to claim 1, wherein the build-up material supply and the laser beam irradiation are delayed with respect to the timing at which the processing point starts to rise.

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