JP6091971B2 - Lap weld joint, fuel injection valve, and laser welding method - Google Patents

Description

  The present invention relates to a lap weld joint in which a plurality of members are joined together, a fuel injection valve including the lap weld joint, and a laser welding method.

  Laser welding is used in various directions because the energy density of the laser beam as a heat source is high, and a weld joint with low distortion, high speed, and high accuracy can be obtained. In the automotive field, a plurality of materials to be welded are overlapped and welded to a steel material such as stainless steel or carbon steel, or a metal material such as an aluminum alloy or a nickel alloy.

  By the way, as shown in FIG. 9, in the heat conduction type laser welding, when a laser beam 104 is irradiated from the surface on the welded material 101 side in a joint formed by overlapping the welded material 101 and the welded material 102, a laser beam is emitted. The light 104 is absorbed by the materials to be welded 101 and 102, and the laser light 104 is converted into heat, whereby heat energy is conducted to the inside of the materials to be welded 101 and 102 to melt the materials to be welded 101 and 102. In this heat conduction type laser welding, the temperature of the molten metal is slightly higher than the melting point, but lower than the temperature at which the metal evaporates, so that the welding phenomenon is stabilized and welding defects such as porosity and spatter are less likely to occur. Thus, since the weld bead width W100 of the weld bead 103 is wider than the penetration depth H100, the penetration depth H100 cannot be increased. Generally, heat conduction laser welding is a thin plate. It is increasingly used for parts. However, when heat conduction laser welding is applied to circumferential welding of a rotating object such as a fuel injection valve (injector) that injects fuel, there is a problem that weld cracks occur in the weld.

  Thus, as a method for preventing the occurrence of such weld cracks, for example, in Patent Document 1, the oxygen gas content of the assist gas is adjusted to 5 to 50% by volume, and the surface width of the weld bead and the joining of a plurality of members are performed. It has been proposed that the ratio with the width of the part (boundary surface) is close to 1.

JP-A-10-85974

  However, in the heat conduction type laser welding as described in Patent Document 1, since the weld bead width W100 of the weld bead 103 is larger than the penetration depth H100, a sufficient penetration depth H100 is obtained when welding thick plates. There is a problem that can not be. Further, although there is a possibility that the penetration depth H100 can be increased by increasing the heat input or decreasing the welding speed, defects such as welding deformation and cracking are likely to occur. Furthermore, in precision small and medium products such as fuel injection valves, the weld bead width W100 is limited, and heat conduction laser welding cannot be applied.

Therefore, a deep penetration depth can be obtained by applying a deep penetration type (keyhole type) laser welding method. FIG. 10A is a diagram showing an overview of deep penetration type (keyhole type) laser welding. In this laser welding method, when the power density (laser output per unit area) of the laser beam 114 applied to the surface of the workpiece 111 becomes 10 ⁶ W / cm ² or more, the metal surfaces of the workpieces 111 and 112 The metal vapor 116 violently jumps from the irradiation point of the laser beam 114 as the plasma is generated, and the molten metal surface is depressed by the reaction force of the metal vapor 116, and the laser beam 114 is emitted from the keyhole 115. The laser beam is incident while repeating reflection, and deep and thin deep penetration type (keyhole type) laser welding is performed. In this way, in comparison with the shape of the weld bead 103 (see FIG. 9) by heat conduction type laser welding, deep penetration type laser welding enables welding with a deeper penetration depth H101, and a penetration depth greater than the weld bead width W101. It is also possible to make H101 several times larger.

  However, as shown in FIG. 10B, in the case of deep penetration laser welding, the weld metal (starting from the intersection P100 between the weld metal (weld bead 113) and the boundary surface 119 of the workpieces 111 and 112) A weld crack 118 is generated up to the inside of the weld bead 113). The mechanism of the occurrence of such weld cracks will be described below with reference to FIG. FIG. 11 is a schematic view of the growth direction of the dendrite structure (dendritic structure) near the boundary surface of the material to be welded and the stress distribution applied to the weld.

  As shown in FIG. 11, generally, in a welding method in which the penetration depth H101 (see FIG. 10 (a)) is deeper than the weld bead width W101 (see FIG. 10 (a)) of the weld bead 113, A tensile stress σ is generated in the longitudinal direction (depth direction, vertical direction in the figure) of the weld metal accompanying the cooling and solidification of the metal. Further, shear stress τ is also generated in the direction along the boundary surface 119 (the left-right direction in the drawing) in the cooling process of the molten metal due to the difference in the size and material of the materials to be welded 111 and 112, the melted region, and the like. Generally, since the structure of the welded portion grows perpendicular to the solid-liquid phase interface, when the angle between the interface 117 of the welded portion and the boundary surface 119 of the workpieces 111 and 112 is 90 °, it is a solidified structure. The growth direction of the dendrite 110 is parallel to the boundary surface 119. That is, the growth direction of the dendrite 110 is parallel to the shear stress τ and perpendicular to the tensile stress σ. As a result, as for the structure of the dendrite 110, the weld crack 118 is generated at the dendrite grain boundary having the weakest resistance to the weld crack.

  The present invention solves the above-described problems of the prior art, and in deep penetration laser welding, a lap weld joint, a fuel injection valve, and laser welding capable of preventing the occurrence of weld cracks in a material to be welded It is an object to provide a method.

The present invention superimposes two materials to be welded, and performs deep penetration welding by evaporating each material to be welded by irradiating a laser beam from one surface side of the material to be welded. The cross-sectional shape of the bead is expressed as follows: (i) An angle θ formed by a boundary line forming the interface of the workpiece and the tangent line of the weld bead at the intersection of the weld bead and the boundary line is 90 ° <θ ≦ And (ii) the ratio D / L between the penetration width L of the weld bead at the boundary line and the penetration depth D from the boundary line to the bottom of the weld bead is 0 .1 <D / L ≦ 1.0 .

  According to the present invention, it is possible to provide a lap weld joint, a fuel injection valve, and a laser welding method capable of preventing the occurrence of weld cracks in a material to be welded in deep penetration laser welding.

The fuel injection valve provided with the lap weld joint which concerns on this embodiment is shown, (a) is a longitudinal cross-sectional view, (b) is the top view seen from the front end side. It is sectional drawing which shows the lap weld joint which concerns on 1st Embodiment. It is a figure explaining the strength test method of a lap weld joint. It is sectional drawing which shows typically the internal structure of a weld bead. (A) is a weld bead sectional shape according to Comparative Example 1, and (b) is a weld bead sectional shape according to Comparative Example 2. It is sectional drawing which shows the lap weld joint which concerns on 2nd Embodiment. It is a graph which shows the relationship between the temperature of a molten pool, and surface tension. It is a figure explaining the effect which concerns on this embodiment. It is sectional drawing which shows the weld bead formed by heat conduction type laser welding. It is sectional drawing which shows the outline | summary of deep penetration type | mold (keyhole type | mold) laser welding. It is a schematic diagram which shows the mechanism of the crack generation in the conventional deep penetration type laser welding.

  Hereinafter, the lap weld joint according to the present embodiment will be described with reference to the drawings. Note that the lap weld joint according to the present embodiment can be applied to, for example, an injection nozzle of a fuel injection valve (also referred to as an injector) F used in an internal combustion engine of an automobile. 1A and 1B show an injection nozzle of a fuel injection valve provided with a lap weld joint according to the present embodiment, wherein FIG. 1A is a longitudinal sectional view and FIG. 1B is a plan view seen from the tip side.

  As shown in FIG. 1A, the fuel injection valve F joins a nozzle plate 1 (a material to be welded) and a nozzle body 2 (a material to be welded) by deep penetration type (keyhole type) laser welding. Is. In FIG. 1, only the injection nozzle at the tip of the fuel injection valve F is shown, and the other parts of the fuel injection valve F, such as a needle, a plunger, and a solenoid, are configured by known techniques. The description is omitted.

  The nozzle plate 1 is made of a material such as austenitic stainless steel, and has a plate thickness of 0.35 mm, for example. The nozzle body 2 is formed in a substantially cylindrical shape with a material such as martensitic stainless steel.

  The nozzle plate 1 has a disk shape having an injection hole 1a through which fuel is injected. The nozzle body 2 has a valve seat 2a with which a needle (valve element) abuts in an internal communication passage, and a communication hole 2b communicating with the injection hole 1a is formed at the center of the tip.

  As shown in FIG. 1B, the nozzle plate 1 is formed with a plurality of injection holes 1 a at positions corresponding to the communication holes 2 b of the nozzle body 2. That is, all the injection holes 1a are formed so as to be located inside the communication holes 2b. The number of the injection holes 1a is not limited to four, and may be three or less or five or more. Moreover, the shape of the injection hole 1a is not limited to a circle, and can be appropriately changed to an ellipse, a polygon, a long hole, an arc, or the like. Further, the position and diameter of the injection hole 1a can be changed as appropriate.

  Further, the fuel injection valve F is formed by superposing the nozzle plate 1 and the nozzle body 2 by deep penetration type (keyhole type) laser welding, and from the nozzle plate 1 side (one side) of the overlapping surface, the nozzle plate. 1 is configured to have a lap weld joint 10A by irradiating laser light along the peripheral edge of 1 (periphery of the communication hole 2b) and performing circumferential welding (full circumference welding, see FIG. 1B). It is. By circumferential welding in this way, the gap at the boundary surface between the nozzle plate 1 and the nozzle body 2 is sealed, so that fuel can be reliably prevented from leaking from the boundary surface.

  In this deep penetration laser welding, for example, a fiber laser with a wavelength of 1070 to 1080 nm can be used, but laser light with other wavelengths may be used. Further, laser light is generated from a laser transmitter (not shown), is condensed through a transfer path, is collected by a condenser lens (not shown), and the surface of the nozzle plate 1 of the fuel injection valve F is irradiated with the laser light.

In the deep penetration laser welding of this embodiment, nitrogen can be used as a shielding gas in order to prevent oxidation of the molten metal. The shielding gas is not limited to nitrogen, and Ar (argon), He (helium), CO ₂ , Air, or a mixed gas thereof may be used. Incidentally, by including a predetermined amount (eg, 50% by mass) of Air in the shielding gas, the contraction force generated when the welded portion is cooled and solidified can be reduced.

  As the welding conditions, for example, the laser output is 100 W to 600 W, the welding speed is 4.0 mm / s to 100 mm / s, and the spot diameter of the laser beam irradiated on the surface of the nozzle plate 1 is 0.05 mm to 0.3 mm. It can be set appropriately. In this laser welding, either continuous wave or pulse wave may be used.

FIG. 2 is a cross-sectional view showing the lap weld joint according to the first embodiment. Although FIG. 2 shows a cross-sectional view, hatching is not shown for convenience of explanation. In the first embodiment, as described above, the power density (laser output per unit area) of the laser beam 114 (see FIG. 10A) irradiated on the surface of the nozzle plate 1 is, for example, 10 ⁶ W / cm ^2. As a result, the temperature of the metal surfaces of the nozzle plate 1 and the nozzle body 2 becomes equal to or higher than the boiling point of the metal, and the metal vapor 116 (see FIG. 10A) is intense from the irradiation point of the laser beam 114 as plasma is generated. The molten metal surface is depressed by the reaction force of the metal vapor 116, and the laser beam 114 is incident while being repeatedly reflected by the keyhole 115 (see FIG. 10A) to obtain a deep and thin welded portion. it can.

  As shown in FIG. 2, the lap weld joint 10A provided with the weld bead 3A was obtained by deep penetration type (keyhole type) laser welding. In this lap weld joint 10A, for example, the surface width W1 of the cross-sectional shape of the weld bead 3A formed on the surface of the nozzle plate 1 is 0.35 mm, and it extends from the surface of the nozzle plate 1 to the bottom 3a of the weld bead 3A. The total penetration depth H1 was 0.5 mm. Further, the penetration width L1 of the weld bead 3A at the depth position of the boundary line 4 (boundary surface) that forms the boundary between the nozzle plate 1 and the nozzle body 2 was 0.2 mm. Further, as described above, the thickness t of the nozzle plate 1 is 0.35 mm, and the depth D1 from the boundary line 4 (boundary surface) to the bottom 3a of the weld bead 3A (dissolution on the nozzle body 2 side below the boundary surface). The depth of insertion) was 0.15 mm.

  As a result, the ratio D1 / L1 (ratio D / L) between the penetration width L1 of the weld bead 3A at the boundary line 4 and the penetration depth D1 from the boundary line 4 to the bottom 3a of the weld bead 3A is 0. .75 and 1.0 or less. Further, the angle θ1 (angle θ) formed by the boundary line 4 that forms the interface between the nozzle plate 1 and the nozzle body 2 and the tangent line TL1 of the weld bead 3A at the intersection P1 of the weld bead 3A and the boundary line 4 is 110. ° and greater than 90 °.

  For the lap weld joint 10A having such a weld bead 3A (weld bead cross-sectional shape), the structure and defects of the welded portion were observed with a microscope. As a result, no weld defects such as weld cracks, porosity, and poor bonding were found in the weld.

  Further, as a result of conducting the strength test of the lap weld joint 10A, it was confirmed that the strength of the lap weld joint 10A was higher than that of the base material because the base material was broken. FIG. 3 is a diagram illustrating a strength test method for a lap weld joint. As shown in FIG. 3, in a state where the fuel injection valve F provided with the lap weld joint 10A is fixed, the pressing pin P is inserted from the communication hole 2b (see FIG. 1) of the nozzle body 2, and the pressing pin P is inserted into the nozzle. A predetermined load F1 is applied to the pressing pin P by contacting the plate 1. The predetermined load F1 applied to the pressing pin P is set to a pressure that can withstand the fuel injection pressure of the fuel injection valve F.

  FIG. 4 is a cross-sectional view schematically showing the internal structure of the weld bead. Incidentally, one of the causes of the occurrence of weld cracks (welding defects) is that the growth direction of the dendrite 110 is parallel to the shear stress τ and perpendicular to the tensile stress σ as described with reference to FIG. . Therefore, in the first embodiment, as shown in FIG. 4, the angle between the growth direction R of the dendrite 10 and the shear stress τ is set to a certain angle from 0 °, that is, the angle θ1 formed by the boundary line 4 and the tangent line TL1 is set to 90. By setting the angle larger than °, the path direction of the dendrite grain boundary (the growth direction R of the dendrite 10) having the weakest resistance to the weld crack is inclined with respect to the shear stress τ, and it is difficult to generate the weld crack. .

  Furthermore, in the lap weld joint 10A according to the first embodiment, the ratio D1 between the penetration width L1 of the weld bead 3A at the boundary line 4 and the penetration depth D1 from the boundary line 4 to the bottom 3a of the weld bead 3A. / L1 is set to 1.0 or less. The reason why the ratio D1 / L1 is set to 1.0 or less in this way is that when D1 / L1 exceeds 1.0, the longitudinal direction of the weld bead 3A (weld bead cross-sectional shape) (the depth direction of the weld bead 3A). This is because the possibility of weld cracking increases even if the tensile stress [sigma] generated in is too large and the angle [theta] 1 between the tangent TL1 of the weld bead 3A and the boundary line 4 is greater than 90 [deg.].

  FIG. 5A shows a weld bead cross-sectional shape according to Comparative Example 1, and FIG. 5B shows a weld bead cross-sectional shape according to Comparative Example 2. In addition, about the structure similar to embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  In the lap weld joint 100A as Comparative Example 1 shown in FIG. 5A, the cross-sectional shape of the weld bead 103A is the boundary line 4, and the tangent TL10 of the weld bead 103A at the intersection P10 of the weld bead 103A and the boundary line 4. The case where the angle θ10 formed by is 90 ° is illustrated. In addition, about ratio D10 / L10 of penetration width L10 and penetration depth D10 (= H10-t), it is set to 1.0 or less. However, even when the ratio D10 / L10 is set to 1.0 or less, if the angle θ10 in the weld bead 103A is set to 90 °, the intersection P10 between the weld bead 103A and the boundary line 4 A weld crack occurs up to the inside of the weld bead 103A (welded metal). As described with reference to FIG. 11, when the angle θ10 is 90 °, the growth direction of the dendrite 110 is parallel to the shear stress τ and is perpendicular to the tensile stress σ. A weld crack 108 is generated at a dendrite grain boundary having the weakest resistance to cracking.

  In the lap weld joint 100B as the comparative example 2 shown in FIG. 5B, the cross-sectional shape of the weld bead 103B is a ratio D20 / L20 (ratio between the penetration width L20 and the penetration depth D20 (= H20-t). (D / L) is greater than 1.0 (D20 / L20> 1). The angle θ20 formed by the boundary line 4 and the tangent line TL20 of the weld bead 103B at the intersection P20 between the weld bead 103B and the boundary line 4 is set to be larger than 90 °. However, even when the angle θ20 is set larger than 90 °, if the ratio D20 / L20 in the cross-sectional shape of the weld bead 103B is set larger than 1.0, the weld bead 103B and the boundary line 4 A weld crack occurs from the intersection P20 to the inside of the weld bead 103B (welded metal). This is because, as described above, when D20 / L20 exceeds 1.0, the tensile stress σ generated in the longitudinal direction (depth direction of the weld bead 3A) of the weld bead 3B (weld bead cross-sectional shape) becomes too large. It is.

  As described above, according to the lap weld joint 10A according to the first embodiment, the cross-sectional shape of the weld bead 3A is such that the angle θ1 is greater than 90 ° and the ratio D1 / L1 is 1.0 or less. With this configuration, it is possible to prevent weld cracking in deep penetration laser welding. Further, by applying the lap weld joint 10A to the fuel injection valve F (see FIG. 1), it is possible to prevent the occurrence of weld cracks when the nozzle plate 1 and the nozzle body 2 are welded.

  In addition, by applying the lap weld joint 10A according to the first embodiment to the fuel injection valve (injection nozzle) F (see FIG. 1), simply changing the shape of the injection hole 1a of the nozzle plate 1 as appropriate. It becomes possible to obtain the fuel injection valve F of a kind. For example, the fuel injection valve F can be appropriately changed according to the vehicle type, the exhaust amount, and the like.

FIG. 6 is a cross-sectional view showing a lap weld joint according to the second embodiment. Although FIG. 6 shows a cross-sectional view, hatching is not shown for convenience of explanation. Also in the second embodiment, as described with reference to FIG. 10A, the power density (laser output per unit area) of the laser light 114 applied to the surface of the nozzle plate 1 is, for example, 10 ⁶ W / cm ² or more. As a result, the temperature of the metal surfaces of the nozzle plate 1 and the nozzle body 2 becomes equal to or higher than the boiling point of the metal, and with the generation of plasma, the metal vapor 116 violently jumps out from the irradiation point of the laser beam 114 and the reaction force of the metal vapor 116 Thus, the molten metal surface is recessed, and the laser beam 114 is incident while being repeatedly reflected by the keyhole 115, so that a deep and thin weld can be obtained.

  As welding conditions, for example, the laser output is 150 W to 800 W, the welding speed is 4.0 mm / s to 100 mm / s, and the spot diameter of the laser light irradiated on the surface of the nozzle plate 1 is 0.15 mm to 0.6 mm. did. In the second embodiment, no shielding gas is used. Further, either a continuous wave or a pulse wave may be used.

  By the way, the lap weld joint 10B which has the weld bead 3B shown in FIG. 6 was obtained by the deep penetration type | mold (keyhole type | mold) laser welding which does not use shielding gas. For example, the surface width W2 of the cross-sectional shape of the weld bead 3B formed on the surface of the nozzle plate 1 is 0.3 mm, and the total penetration depth H2 from the surface of the nozzle plate 1 to the bottom of the weld bead 3B is It was 0.43 mm. Further, the penetration width L2 of the weld bead 3B at the depth position of the boundary line 4 (boundary surface) that forms the boundary between the nozzle plate 1 and the nozzle body 2 was 0.25 mm. Further, since the thickness t of the nozzle plate 1 is 0.35 mm, the depth D2 from the boundary line 4 (boundary surface) to the bottom 3a of the weld bead 3B (the penetration depth on the nozzle body 2 side below the boundary surface) ) Was 0.08 mm.

  As a result, the ratio D2 / L2 (ratio D / L) between the penetration width L2 of the weld bead 3B at the boundary line 4 and the penetration depth D2 from the boundary line 4 to the bottom 3a of the weld bead 3B is 0. .32 and 1.0 or less. Further, the angle θ2 (angle θ) formed by the boundary line 4 forming the interface between the nozzle plate 1 and the nozzle body 2 and the tangent line TL2 of the weld bead 3B at the intersection P2 of the weld bead 3B and the boundary line 4 is 120. ° and greater than 90 °.

Now, the reason why the weld bead 3B having the cross-sectional shape shown in FIG. 6 is obtained will be described below. The weld bead 3B according to the second embodiment is obtained when a shield gas is not used, or when a shield gas containing a gas (for example, oxygen, CO ₂ ) that can be oxidized with a metal element such as Fe (iron) is used. It is That is, when shield gas is not used, when using shield gas as described above, it is necessary to select an appropriate material to be welded, such as stainless steel containing a large amount of iron (Fe), as in the embodiment, etc. Can be applied to.

In general, when a shielding gas (such as nitrogen) is used, the surface tension of the molten iron (Fe) decreases as the temperature T increases as shown in the graph A (solid line) in FIG. The hot water flow (metal flow) on the surface flows from the central portion having a high temperature toward the outer peripheral portion having a low temperature, and as a result, a wide welding width is formed. On the other hand, when oxygen or CO ₂ is contained in the shielding gas, the amount of oxygen in the molten metal increases. As shown in graph B (broken line) in FIG. Conversely, it increases with increasing temperature. As a result, the hot water flow on the surface of the molten pool flows from the outer periphery of the molten pool having a low temperature toward the central portion having a high temperature. Thus, as a result of the hot water flow toward the center, the width of the molten pool becomes narrower, and the surface width W2 (see FIG. 6) of the weld bead 3B formed after solidification is the surface width W1 (see FIG. 6) of the weld bead 3A. 2). Even when the shield gas is not used, the oxygen content of the molten metal is increased by the oxygen contained in the air, so that a weld bead 3B having a narrow surface width W2 is obtained as described above.

  As described above, the weld bead 3B is obtained by welding without using the shield gas or by using the shield gas containing the gas that oxidizes and reacts with the nozzle plate 1 and the nozzle body 2 to obtain a thin weld bead. 3B can be obtained, and can be suitably applied to welding of a portion where the welding width cannot be increased, such as the injection nozzle of the fuel injection valve F.

  About the lap weld joint 10B which has such a weld bead 3B (weld bead cross-sectional shape), the structure | tissue and the defect of the welding part were observed with the microscope similarly to 1st Embodiment. As a result, no weld defects such as weld cracks, porosity, and poor bonding were found in the weld. Moreover, as a result of carrying out the strength test of the lap weld joint 10B by the method shown in FIG. 3, it was confirmed that the strength of the lap weld joint 10B was higher than that of the base material because the base material was broken.

  A summary of the above results is shown in FIG. FIG. 8 is a diagram for explaining the effect according to the present embodiment. In addition, after performing the grinding | polishing and the etching operation | work with respect to all the welding samples, it observed with the optical microscope and investigated the presence or absence of the crack in the inside of a weld metal. “Crack” shown in FIG. 8 indicates that a weld crack was confirmed, “good” indicates that a weld crack was not confirmed, and “joint failure” indicates that the nozzle plate 1 and the nozzle body 2 This indicates that the bonding was not completed.

  As shown in FIG. 8, in the lap weld joint 10A of the first embodiment and the lap weld joint 10B of the second embodiment, when D / L ≦ 1.0 and θ> 90 °, a weld defect (weld crack) It was confirmed that good welding was performed without occurrence of). Note that when D / L> 1.0, weld cracks occurred, and when θ = 90 °, weld cracks also occurred.

  In the lap weld joint 10A and the lap weld joint 10B, it is preferable to set 0.1 <D / L ≦ 1.0 and 90 ° <θ ≦ 130 °. In addition, when D / L ≦ 0.1, poor bonding occurred, and when θ> 130 °, weld cracks occurred. When θ exceeds 130 °, the surface width of the weld bead is remarkably increased in order to ensure a constant penetration width. Thus, even when the difference between the surface width and the penetration width of the weld bead is large, a weld crack is generated from the intersection of the weld bead and the boundary line toward the inside of the weld bead. Note that the lower limit value (> 0.1) of D / L and the upper limit value (≦ 130 °) of θ shown in FIG. 6 are merely examples, and are not limited to the present embodiment. It varies depending on the type of metal material used for the nozzle body 2 and welding conditions. Therefore, the lower limit value of D / L is set to a ratio (value) at which no joint failure occurs, and the upper limit value of θ is set to an angle at which no weld crack occurs.

1 Nozzle plate (material to be welded)
2 Nozzle body (material to be welded)
3A, 3B Weld bead 3a Bottom 4 Boundary line 10A, 10B Lap weld joint D1, D2 Penetration depth F Fuel injection valve L1, L2 Penetration width P1, P2 Intersection TL1, TL2 Tangent θ1, θ2 Angle

Claims (5)

Cross-sectional shape of the weld bead by superimposing two welded materials, irradiating laser beam from one surface side of the welded material to evaporate each of the welded materials, and performing deep penetration welding The
(I) An angle θ formed between a boundary line forming the interface of the workpiece and a tangent line of the weld bead at an intersection of the weld bead and the boundary line is 90 ° <θ ≦ 130 ° , and ,
(Ii) The ratio D / L between the penetration width L of the weld bead at the boundary line and the penetration depth D from the boundary line to the bottom of the weld bead is 0.1 <D / L ≦ A lap weld joint characterized by being configured to be 1.0 .   2. The lap weld joint according to claim 1, wherein the weld bead is welded without using a shield gas or using a shield gas containing a gas that oxidizes and reacts with the workpiece. . A fuel injection valve having an injection nozzle for injecting fuel,
The spray nozzle is
A nozzle plate formed with injection holes;
A nozzle body on which the nozzle plates are stacked and having a communication path communicating with the injection hole,
The fuel injection valve according to claim 1, wherein the nozzle plate and the nozzle body are formed by circumferential welding of the lap weld joint according to claim 1 or 2 by irradiating laser light from the nozzle plate side. Cross-sectional shape of the weld bead by superimposing two welded materials, irradiating laser beam from one surface side of the welded material to evaporate each of the welded materials, and performing deep penetration welding The
(I) An angle θ formed between a boundary line forming the interface of the workpiece and a tangent line of the weld bead at an intersection of the weld bead and the boundary line is 90 ° <θ ≦ 130 ° , and ,
(Ii) The ratio D / L between the penetration width L of the weld bead at the boundary line and the penetration depth D from the boundary line to the bottom of the weld bead is 0.1 <D / L ≦ A laser welding method, characterized by being 1.0 .   The laser welding method according to claim 4, wherein welding is performed without using a shielding gas, or welding is performed using a shielding gas containing a gas that oxidizes and reacts with the workpiece.