Shielding gas supply device and method

Abstract

To improve shield performance by suppressing entrainment of surrounding air into a shield gas on a shield gas supply device and a method.SOLUTION: A shield gas supply device includes: a first nozzle for jetting a first shield gas at a preset first speed along a shield surface; and a second nozzle disposed on an outside the first nozzle and jetting a second shield gas at a second speed which is slower than the first speed along the first shield gas.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a shielding gas supply device and method.

Background Art

[0002] When performing various processes by irradiating a laser beam, an electron beam, etc. on a processed surface of a metal, a shielding gas supply device prevents oxidation by supplying a shielding gas to the processed surface. As a conventional shielding gas supply device, there is one described in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A shielding gas supply device needs to appropriately adjust the ejection amount of the shielding gas with respect to the processed surface. If the ejection amount of the shielding gas of the shielding gas supply device is small, the shielding of the processed surface by the shielding gas becomes insufficient, and it becomes difficult to prevent oxidation of the processed surface. On the other hand, if the ejection amount of the shielding gas of the shielding gas supply device is large, although it is effective in preventing oxidation of the processed surface, the running cost increases. Further, if the ejection speed of the shielding gas of the shielding gas supply device is high, the shielding gas entangles the surrounding air, and oxygen comes into contact with the processed surface, making it difficult to prevent oxidation.

[0005] <000​​​​​​​To achieve the above objectives, the shielding gas supply device of the present disclosure comprises a first nozzle that ejects a first shielding gas along a shielding surface at a preset first velocity, and a second nozzle positioned outside the first nozzle that ejects a second shielding gas along the first shielding gas at a second velocity lower than the first velocity.

[0007] Furthermore, the shielding gas supply method of this disclosure comprises the steps of: ejecting a first shielding gas along a shield surface at a preset first velocity; and ejecting a second shielding gas outside the first shielding gas along the first shielding gas at a second velocity lower than the first velocity. [Effects of the Invention]

[0008] According to the shielding gas supply device and method of this disclosure, shielding performance can be improved by suppressing the entrainment of ambient air into the shielding gas. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view showing the shielding gas supply device of this embodiment. [Figure 2] Figure 2 is a front view of the shielding gas supply device. [Figure 3] Figure 3 is a side view of the shielding gas supply device. [Figure 4] Figure 4 is a plan view of the shielding gas supply system. [Figure 5] Figure 5 is an exploded perspective view showing the inside of the shielding gas supply device. [Figure 6] Figure 6 is a graph showing the position of the nozzle surface in the height direction and the second derivative of the nozzle surface relative to the nozzle axial position of the shielding gas supply device. [Figure 7] Figure 7 is a schematic diagram illustrating the operation of a conventional shielding gas supply device. [Figure 8] Figure 8 is a schematic diagram illustrating the operation of the shielding gas supply device of this embodiment. [Figure 9] Figure 9 is a front view showing a first modified example of the first nozzle and the second nozzle. [Figure 10] Figure 10 is a front view showing a second modified example of the first nozzle and the second nozzle. [Figure 11] Figure 11 is a front view showing a third modified example of the first and second nozzles. [Figure 12] Figure 12 is a front view showing a fourth modified example of the first and second nozzles. [Figure 13] Figure 13 is a front view showing a fifth modified example of the first and second nozzles. [Figure 14] Figure 14 is a front view showing a sixth modified example of the first and second nozzles. [Figure 15] Figure 15 is a front view showing a seventh modified example of the first and second nozzles. [Figure 16] Figure 16 is a front view showing an eighth modified example of the first and second nozzles. [Figure 17] Figure 17 is a side view showing a ninth modified example of the first and second nozzles. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.

[0011] <Overview of Shielding Gas Supply System> The shielding gas supply device of this embodiment is applied to, for example, a three-dimensional laminating device that forms a three-dimensional laminate using powder such as metal powder as a raw material. As one of the laminating manufacturing methods by the three-dimensional laminating device, there is a powder bed method, in which a laser beam, an electron beam, or the like is irradiated onto the smooth surface of the metal powder in the object to be processed to melt it. At this time, the shielding gas supply device supplies an inert gas along the smooth surface of the metal powder to prevent contact of oxygen with the processing surface and prevent oxidation of the processing surface. However, the shielding gas supply device of this embodiment is not limited to the three-dimensional laminating device and can also be applied to other processing devices (for example, an arc welding device, etc.) that perform various processes using a laser beam or the like.

[0012] FIG. 1 is a perspective view showing the shielding gas supply device of this embodiment.

[0013] As shown in FIG. 1, the shielding gas supply device 10 includes a first nozzle 11 and a second nozzle 12.

[0014] The first nozzle 11 ejects the first shielding gas G1 at a first speed preset along the shielding surface 100. The second nozzle 12 is disposed outside the first nozzle 11. The second nozzle 12 ejects the second shielding gas G2 at a second speed lower than the first speed along the first shielding gas G1 around the first shielding gas G1. In this case, the ejection direction of the first shielding gas G1 from the first nozzle 11 and the ejection direction of the second shielding gas G2 from the second nozzle 12 are the same direction.

[0015] In this embodiment, the shield surface 100 is a plane aligned horizontally, and the shield gas supply device 10 ejects shield gases G1 and G2 onto the shield surface 100 along the shield surface 100. In other words, the ejection direction of shield gases G1 and G2 by the shield gas supply device 10 is parallel to the shield surface 100. In the following description, the horizontal direction parallel to the ejection direction of shield gases G1 and G2 will be referred to as the X direction, the horizontal direction perpendicular to the X direction (which is parallel to the ejection direction of shield gases G1 and G2) and parallel to the shield surface 100 will be referred to as the Y direction, and the vertical direction perpendicular to the horizontal X and Y directions will be referred to as the Z direction.

[0016] <Configuration of the shielding gas supply system> Figure 2 is a front view of the shielding gas supply device, Figure 3 is a side view of the shielding gas supply device, Figure 4 is a top view of the shielding gas supply device, and Figure 5 is an exploded perspective view showing the interior of the shielding gas supply device.

[0017] As shown in Figures 2 to 5, the first nozzle 11 has a connecting portion 21, a first bent portion 22, a second bent portion 23, and a nozzle portion 24.

[0018] The connecting section 21 has a rectangular hollow shape, and a first flow path C11 is formed along the Z direction. The supply pipe 25 is connected to the lower end of the connecting section 21 in the Z direction. One end of the first bent section 22 is connected to the upper end of the connecting section 21 in the Z direction. The first bent section 22 has a rectangular hollow shape, and a second flow path C12 is formed that bends approximately 90 degrees from the Z direction to the Y direction. One end of the second bent section 23 is connected to the other end of the first bent section 22. The second bent section 23 has a rectangular hollow shape, and a third flow path C13 is formed that bends approximately 90 degrees from the Y direction to the X direction. One end of the nozzle section 24 is connected to the other end of the second bent section 23. The nozzle section 24 has a rectangular hollow shape, and a fourth flow path C14 is formed along the X direction. The other end of the nozzle section 24 opens toward the shield surface 100.

[0019] The second nozzle 12 has a connecting portion 31, a first bent portion 32, a second bent portion 33, and a nozzle portion 34.

[0020] The connecting section 31 has a rectangular hollow shape, and a first flow path C21 is formed along the Z direction. The supply pipe 35 is connected to the lower end of the connecting section 31 in the Z direction. One end of the first bent section 32 is connected to the upper end of the connecting section 31 in the Z direction. The first bent section 32 has a rectangular hollow shape, and a second flow path C22 is formed that bends approximately 90 degrees from the Z direction to the Y direction. One end of the second bent section 33 is connected to the other end of the first bent section 32. The second bent section 33 has a rectangular hollow shape, and a third flow path C23 is formed that bends approximately 90 degrees from the Y direction to the X direction. One end of the nozzle section 34 is connected to the other end of the second bent section 33. The nozzle section 34 has a rectangular hollow shape, and a fourth flow path C24 is formed along the X direction. The other end of the nozzle section 34 opens toward the shield surface 100.

[0021] The connecting portion 21, first bent portion 22, and second bent portion 23 of the first nozzle 11 and the connecting portion 31, first bent portion 32, and second bent portion 33 of the second nozzle 12 are positioned offset by a predetermined distance in the X direction. The second bent portion 33 and nozzle portion 34 of the second nozzle 12 are positioned outside the second bent portion 23 and nozzle portion 24 of the first nozzle 11. In other words, the second bent portion 33 and nozzle portion 34 of the second nozzle 12 cover the upper and left-right sides of the second bent portion 23 and nozzle portion 24 of the first nozzle 11 with a predetermined gap between them. As a result, the nozzle portion 34 of the second nozzle 12 has a first outlet 34a above the first nozzle 11 and second outlets 34b and 34c in the left-right direction (width direction) of the first nozzle 11.

[0022] The first nozzle 11 has one end of the first supply channel 26 connected to the supply pipe 25, and the first supply channel 26 is equipped with a first flow control valve 27. The second nozzle 12 has one end of the second supply channel 36 connected to the supply pipe 35, and the second supply channel 36 is equipped with a second flow control valve 37. The other ends of the first supply channel 26 and the second supply channel 36 are connected to a supply channel 28 and merge, and a supply source 29 is connected to the supply channel 28. The supply source 29 is capable of storing inert gases as shielding gases G1 and G2. Here, the inert gases used can be, for example, nitrogen gas (N2), argon gas (Ar), or helium gas (He).

[0023] The first nozzle 11 adjusts the supply amount of the first shielding gas G1 by adjusting the opening degree of the first flow control valve 27, thereby adjusting the flow velocity (flow rate per unit time) of the first shielding gas G1 ejected from the nozzle section 24. Similarly, the second nozzle 12 adjusts the supply amount of the second shielding gas G2 by adjusting the opening degree of the second flow control valve 37, thereby adjusting the flow velocity (flow rate per unit time) of the second shielding gas G2 ejected from the nozzle section 34. In the shielding gas supply device 10, the second velocity of the shielding gas G2 ejected from the second nozzle 12 is lower than the first velocity of the first shielding gas G1 ejected from the first nozzle 11.

[0024] Therefore, the first nozzle 11 ejects the first shielding gas G1 at high speed along the shield surface 100, and the second nozzle 12 ejects the second shielding gas G2 at low speed along the first shielding gas G1 on the outside of the first shielding gas G1, excluding the side facing the shield surface 100. As a result, at the interface between the first shielding gas G1 and the second shielding gas G2, the first shielding gas G1 mixes with the surrounding second shielding gas G2 and takes in a portion of the second shielding gas G2. Also, at the interface between the second shielding gas G2 and the surrounding air, the second shielding gas G2 mixes with the surrounding air and takes in a portion of the air.

[0025] The second velocity of the second shielding gas G2 is low and lower than the first velocity of the first shielding gas G1. Consequently, the low-velocity second shielding gas G2 takes in less ambient air. The high-velocity first shielding gas G1 takes in more ambient air from the second shielding gas G2, but because the second shielding gas G2 is an inert gas, the mixing of oxygen (air) into the first shielding gas G1 is suppressed.

[0026] As described above, based on the entrainment velocity and spread angle of the entrainment flow in the first shield gas G1 from the first nozzle 11, the induced flow velocity from the surrounding space, the second shield gas G2, is approximately 1 / 5 to 1 / 6 of the first velocity of the first shield gas G1 from the first nozzle 11. Therefore, if the second velocity of the second shield gas G2 from the second nozzle 12 is 1 / 5 or less of the first velocity, it will be accelerated to the entrainment velocity by the first shield gas G1 from the first nozzle 11, making it less likely for entrainment flow caused by the low-speed second shield gas G2 to occur. For this reason, it is preferable that the second velocity of the second shield gas G2 be 1 / 5 or less (1 / 5 to 1 / 6) of the first velocity of the first shield gas G1. On the other hand, if the second velocity of the second shield gas G2 exceeds 1 / 5 of the first velocity of the first shield gas G1, additional entrainment flow will be generated by the low-speed second shield gas G2 itself, and circulating vortices will be generated in the space where the surrounding air is located.

[0027] <Shape of the nozzle> Figure 6 is a graph showing the position of the nozzle surface in the height direction and the second derivative of the nozzle surface relative to the nozzle axial position of the shielding gas supply device.

[0028] As shown in Figures 2 and 3, in the first nozzle 11, the nozzle section 24 has a lower wall 41, an upper wall 42, and left and right side walls 43 and 44. In the nozzle section 24, the inner surfaces of the lower wall 41 and the upper wall 42 are parallel to each other, and the inner surfaces of the left and right side walls 43 and 44 are parallel to each other. The nozzle section 24 has a rectangular flow path formed by the lower wall 41, the upper wall 42, and the left and right side walls 43 and 44. Preferably, the inner surface of the lower wall 41 is parallel to the shield surface 100 and is continuous without any steps.

[0029] The nozzle portion 24 is formed with a curved surface such that the flow area gradually decreases toward the downstream side in the flow direction of the first shield gas G1. As shown in Figures 3 and 6, the nozzle portion 24 has a curved surface portion 45 formed on the upper wall 42. The curved surface portion 45 has an upstream curved surface 45a that is convex outward on the upstream side in the flow direction of the first shield gas G1, and a downstream curved surface 45b that is convex inward on the downstream side in the flow direction of the first shield gas G1. An inflection point P1 is provided between the upstream curved surface 45a and the downstream curved surface 45b of the curved surface portion 45. The inflection point P1 is in a cross-section passing through the centroid of the first nozzle 11. Preferably, the upper wall 42 has an upstream parallel section parallel to the lower wall 41 on the upstream side of the curved surface 45 in the flow direction of the first shield gas G1, and a downstream parallel section parallel to the lower wall 41 on the downstream side of the curved surface 45 in the flow direction of the first shield gas G1.

[0030] Here, the shape of the upper wall 42 (curved surface 45) in the nozzle section 24 is expressed by the second derivative. For example, if there is a function y=f(x) defined in a single interval on a number line, and a finite limit exists for x belonging to this interval, then the function f is differentiable at x. This limit (rate of increase) is called the derivative of the function f at x. That is, the second derivative at the upstream surface 45a is negative, the second derivative at the downstream surface 45b is positive, and an inflection point P1 is located between the upstream surface 45a and the downstream surface 45b. The inflection point P1 is the point where the second derivative changes from negative to positive.

[0031] In this embodiment, the nozzle portion 24 of the first nozzle 11 is parallel to the shield surface 100 and has a long rectangular shape along the width direction (Y direction) perpendicular to the flow direction of the first shield gas G1. The curved surface portion 45 having an inflection point P1 is provided at least on the upper wall 42 facing the shield surface 100, that is, on the surface adjacent to the first outlet 34a of the second nozzle 12. Note that the curved surface portion having an inflection point may be provided not only on the upper wall 42 but also on the left and right side walls 43, 44, that is, on the surfaces adjacent to the second outlets 34b, 34c of the second nozzle 12.

[0032] On the other hand, as shown in Figures 2 and 3, the second nozzle 12 is positioned parallel to the first nozzle 11 on the outside. That is, the nozzle portion 34 of the second nozzle 12 has a lower wall 51, an upper wall 52, and left and right side walls 53, 54. The inner surfaces of the lower wall 51 and the upper wall 52 of the nozzle portion 34 are parallel to each other, and the inner surfaces of the left and right side walls 53, 54 are parallel to each other. The lower wall 51, the upper wall 52 and the left and right side walls 53, 54 form a rectangular flow path in the nozzle portion 34. The inner surface of the lower wall 51 is parallel to that of the first nozzle 11. Lower wall 41 It comes into contact with the outer surface.

[0033] The nozzle portion 34 is formed with a curved surface such that the flow area gradually decreases toward the downstream side in the flow direction of the second shield gas G2 when the first nozzle 11 is not positioned inside. The nozzle portion 34 has a curved surface portion 55 formed on the upper wall 52. The curved surface portion 55 has an upstream curved surface 55a that is convex outward on the upstream side in the flow direction of the first shield gas G1, and a downstream curved surface 55b that is convex inward on the downstream side in the flow direction of the first shield gas G1. An inflection point P2 is provided between the upstream curved surface 55a and the downstream curved surface 55b of the curved surface portion 55. Preferably, the upper wall 52 has an upstream parallel portion parallel to the lower wall 51 located upstream of the curved surface portion 55 in the flow direction of the second shield gas G2, and a downstream parallel portion parallel to the lower wall 51 located downstream of the curved surface portion 55 in the flow direction of the second shield gas G2.

[0034] Furthermore, if the shape of the upper wall 52 (curved surface 55) in the nozzle section 34 is expressed using the second derivative, then, similar to the nozzle section 24, the second derivative at the upstream curved surface 55a is negative, and the second derivative at the downstream curved surface 55b is positive, with an inflection point P2 located between the upstream curved surface 55a and the downstream curved surface 55b. The inflection point P2 is the point where the second derivative changes from negative to positive.

[0035] In this embodiment, the nozzle portion 34 of the second nozzle 12 is parallel to the shield surface 100 and has a long rectangular shape along the width direction (Y direction) perpendicular to the flow direction of the second shield gas G2, and the curved portion 55 having an inflection point P2 is provided at least on the upper wall 52 facing the shield surface 100. In practice, the flow path through which the second shield gas G2 flows is the flow path between the nozzle portion 24 and the nozzle portion 34, and the flow path area between the nozzle portion 24 and the nozzle portion 34 is substantially constant toward the downstream side in the flow direction of the second shield gas G2. Note that the curved portion having an inflection point may be provided not only on the upper wall 52 but also on the left and right side walls 53 and 54.

[0036] Therefore, the first nozzle 11 ejects the first shielding gas G1 from the nozzle section 24 along the shielding surface 100. At this time, the nozzle section 24 has a gradually decreasing flow path area and an upstream curved surface 45a and a downstream curved surface 45b, with an inflection point P1 located between them, so that the first shielding gas G1 does not separate from the inner surface of the upper wall 42 of the nozzle section 24 and the first velocity increases. As a result, the velocity distribution of the first shielding gas G1 when ejected from the downstream end of the nozzle section 24 is made uniform, and the turbulence of the flow of the first shielding gas G1 is reduced. The second nozzle 12 ejects the second shielding gas G2 from the nozzle section 34 around the first shielding gas G1. At this time, the nozzle section 34 has an upstream curved surface 55a and a downstream curved surface 55b, with an inflection point P2 located between them, so that the second shielding gas G2 does not separate from the inner surface of the upper wall 52 of the nozzle section 34.

[0037] <Rectification mechanism> As shown in Figures 2 to 5, the first nozzle 11 has a flow straightening mechanism consisting of a first guide vane 61, a perforated plate 62, a second guide vane 63, a first mesh (wire mesh) 64, a honeycomb core 65, a second mesh (wire mesh) 66, and a third mesh (wire mesh) 67. The first guide vane 61, the perforated plate 62, the second guide vane 63, the first mesh 64, the honeycomb core 65, the second mesh 66, and the third mesh 67 are arranged in order from the upstream side to the downstream side in the flow direction of the first shield gas G1.

[0038] Multiple first guide vanes 61 are arranged at intervals in the second flow path C12 of the first bend 22. The perforated plate 62 is positioned between the first bend 22 and the second bend 23. Multiple second guide vanes 63 are arranged at intervals in the third flow path C13 of the second bend 23. The first mesh 64, honeycomb core 65, and second mesh 66 are positioned between the second bend 23 and the nozzle section 24. The third mesh 67 is provided at the downstream end of the first shield gas G1 in the flow direction of the nozzle section 24.

[0039] Here, the first mesh 64, honeycomb core 65, and second mesh 66 function as an upstream flow straightening mechanism positioned upstream of the curved surface 45 in the flow direction of the first shield gas G1, while the third mesh 67 functions as a downstream flow straightening mechanism positioned downstream of the curved surface 45 in the flow direction of the first shield gas G1. The first mesh 64, honeycomb core 65, and second mesh 66 as the upstream flow straightening mechanism, and the third mesh 67 as the downstream flow straightening mechanism, have partitions along the flow direction of the first shield gas G1. Here, the partitions are, in the case of meshes 64, 66, and 67, made of materials such as metal or resin, and in the case of the honeycomb core 65, are walls that form a cavity. The thickness of the partition of the third mesh 67 as the downstream flow straightening mechanism is thinner than the thickness of the partitions of the first mesh 64, honeycomb core 65, and second mesh 66 as the upstream flow straightening mechanism. Here, the thickness of the partition refers to the length of the partition in the direction perpendicular to the flow direction of the first shield gas G1. The thinner the partition, the better the flow straightening performance. In other words, a thinner partition results in less turbulence in the flow of the first shield gas G1.

[0040] On the other hand, the second nozzle 12 has a flow straightening mechanism consisting of a guide vane 71, a first mesh (wire mesh) 72, and a second mesh (wire mesh) 73. The guide vane 71, the first mesh 72, and the second mesh 73 are arranged in order from the upstream side to the downstream side in the flow direction of the second shield gas G2.

[0041] Multiple guide vanes 71 are arranged at intervals in the second flow path C22 of the first bend 32. The first mesh 72 is positioned between the second bend 33 and the nozzle 34. The second mesh 73 is provided at the downstream end of the second shield gas G2 in the flow direction of the nozzle 34. The first mesh 72 and the second mesh 73 are provided in the same positions as the second mesh 66 and the third mesh 67 in the first nozzle 11 and may be formed integrally.

[0042] In addition, the first nozzle 11 is provided with a first guide vane 61, a perforated plate 62, a second guide vane 63, a first mesh 64, a honeycomb core 65, a second mesh 66, and a third mesh 67 as a flow straightening mechanism, but the configuration is not limited to this. Similarly, the second nozzle 12 is provided with a guide vane 71, a first mesh 72, and a second mesh 73 as a flow straightening mechanism, but the configuration is not limited to this.

[0043] Therefore, the first shielding gas G1 is first supplied from the supply pipe 25 to the connecting section 21, flows through the first flow path C11, passes through the second flow path C12 of the first bend section 22, and reaches the second bend section 23. At this time, the first shielding gas G1 is guided by the first guide vane 61 and straightened through the perforated plate 62. Next, the first shielding gas G1 passes through the third flow path C13 of the second bend section 23 and reaches the nozzle section 24. At this time, the first shielding gas G1 is guided by the second guide vane 63 and straightened through the first mesh 64, honeycomb core 65, and second mesh (wire mesh) 66. The first shielding gas G1 is then straightened through the third mesh 67 and ejected to the outside.

[0044] Meanwhile, the second shielding gas G2 is first supplied from the supply pipe 35 to the connecting section 31, flows through the first flow path C21, passes through the second flow path C22 of the first bend section 32, and reaches the second bend section 33. At this point, the second shielding gas G2 is guided by the guide vane 71. The second shielding gas G2 then passes through the third flow path C23 of the second bend section 33 and reaches the nozzle section 34. At this point, the second shielding gas G2 is rectified through the first mesh 72. The second shielding gas G2 is then rectified through the second mesh 73 and ejected to the outside.

[0045] The first shield gas G1 and the second shield gas G2 are rectified before being ejected to the outside along the shield surface 100, which uniformizes the velocity distribution when ejected from the downstream ends of the nozzle sections 24 and 34, thereby reducing turbulence in the flow of the first shield gas G1 and the second shield gas G2.

[0046] <Shielding gas supply method> Figure 7 is a schematic diagram illustrating the operation of a conventional shielding gas supply device, and Figure 8 is a schematic diagram illustrating the operation of the shielding gas supply device of this embodiment.

[0047] The shielding gas supply method includes the steps of: ejecting a first shielding gas G1 along the shield surface 100 at a preset first velocity; and ejecting a second shielding gas G2 along the first shielding gas G1 at a second velocity lower than the first velocity, outside the first shielding gas G1 except on the side of the shield surface 100.

[0048] In other words, the first nozzle 11 ejects the first shielding gas G1 at high speed from the nozzle section 24 along the shielding surface 100, and the second nozzle 12 ejects the second shielding gas G2 at low speed from the nozzle section 34 around the first shielding gas G1. At this time, since the second velocity of the second shielding gas G2 is lower than the first velocity of the first shielding gas G1, the amount of ambient air taken in by the second shielding gas G2 is small, and the first shielding gas G1 takes in the ambient second shielding gas G2, thus suppressing the mixing of air (oxygen) into the first shielding gas G1.

[0049] As shown in Figure 7, in the conventional shielding gas supply device 001, the flow path area of ​​the nozzle section 002 decreases linearly (or curvilinearly) toward the downstream side in the flow direction of the shielding gas G, and the velocity of the shielding gas G is the first velocity of the first shielding gas G1 in this embodiment. Therefore, a large vortex V is generated at the interface due to the velocity difference between the high-speed shielding gas G and the surrounding air. As a result, the shielding gas G takes in a large amount of surrounding air, and the oxygen in the taken-in air flows to the shield surface 100, potentially oxidizing the processed surface.

[0050] On the other hand, the shield gas supply device 10 of this embodiment has a double first nozzle 11 and a second nozzle 12, and the second velocity of the second shield gas G2 is lower than the first velocity of the first shield gas G1. In addition, the flow area of ​​each nozzle section 24, 34 gradually decreases toward the downstream side in the flow direction of the shield gases G1, G2, and curved sections 45, 55 having inflection points P1, P2 are provided on the upper walls 42, 52. As a result, the velocity distribution of the first shield gas G1 is uniform when it is ejected onto the shield surface 100 without separating from the inner surfaces of the upper walls 42, 52 of the nozzle sections 24, 34, and flow turbulence is reduced.

[0051] Furthermore, the velocity difference between the low-speed second shielding gas G2 and the surrounding air is small, resulting in small vortices V2 formed at the interface. Consequently, the amount of surrounding air taken in by the second shielding gas G2 is reduced. Also, the velocity difference between the high-speed first shielding gas G1 and the surrounding second shielding gas G2 is small, resulting in small vortices V1 formed at the interface. Moreover, since the second shielding gas G2 is the same inert gas as the first shielding gas G1, the oxygen in the air taken in by the second shielding gas G2 hardly flows through the first shielding gas G1 to the shielding surface 100, thus suppressing oxidation of the processed surface.

[0052] <Modified nozzle> Figure 9 is a front view showing a first modified example of the first nozzle and the second nozzle.

[0053] In the first modified example, as shown in Figure 9, the shielding gas supply device 10A has a first nozzle 11 and a second nozzle 12A. The first nozzle 11 is the same as in the embodiment described above.

[0054] The second nozzle 12A has a nozzle section 34A, which has first outlets 34a1 and 34a2 and second outlets 34b and 34c. The first outlet 34a1 is located on the side of the first nozzle 11 opposite the shield surface 100, that is, above the first nozzle 11, and the first outlet 34a2 is located on the side of the first nozzle 11 facing the shield surface 100, that is, below the first nozzle 11. The second outlets 34b and 34c are located on both sides of the first nozzle 11 in the left-right direction (width direction). The other configurations are the same as in the embodiment described above.

[0055] The first nozzle 11 ejects the first shielding gas G1 at high speed along the shielding surface 100, and the second nozzle 12 ejects the second shielding gas G2 at low speed around the first shielding gas G1, along the first shielding gas G1.

[0056] Figure 10 is a front view showing a second modified example of the first nozzle and the second nozzle.

[0057] In the second modified example, as shown in Figure 10, the shielding gas supply device 10B has a first nozzle 11 and a second nozzle 12B. The first nozzle 11 is the same as in the embodiment described above.

[0058] The second nozzle 12B has a nozzle section 34B, which has a first nozzle 34a and a second nozzle 34b. The first nozzle 34a is located on the opposite side of the first nozzle 11 from the shield surface 100, that is, above the first nozzle 11, and the second nozzle 34b is located on one side (left) of the first nozzle 11 in the left-right direction (width direction). The second nozzle may be located on the other side (right) of the first nozzle 11 in the left-right direction (width direction). The other configurations are the same as in the embodiments described above.

[0059] Figure 11 is a front view showing a third modified example of the first and second nozzles.

[0060] In the third modified example, as shown in Figure 11, the shielding gas supply device 10C has a first nozzle 11 and a second nozzle 12C. The first nozzle 11 is the same as in the embodiment described above.

[0061] The second nozzle 12C has a nozzle portion 34C, and the nozzle portion 34C has a first outlet 34a. The first outlet 34a is located on the opposite side of the shield surface 100 of the first nozzle 11, that is, above the first nozzle 11. The other configurations are the same as in the embodiment described above.

[0062] Figure 12 is a front view showing a fourth modified example of the first and second nozzles.

[0063] In the fourth modified example, as shown in Figure 12, the shielding gas supply device 10D has a first nozzle 11 and a second nozzle 12D. The first nozzle 11 is the same as in the embodiment described above.

[0064] The second nozzle 12D has a nozzle section 34D, and the nozzle section 34D has second outlets 34b and 34c. The second outlets 34b and 34c are located on both sides of the first nozzle 11 in the left-right direction (width direction). The other configurations are the same as those of the embodiment described above.

[0065] Figure 13 is a front view showing a fifth modified example of the first and second nozzles.

[0066] In the fifth modified example, as shown in Figure 13, the shielding gas supply device 10E has a first nozzle 11 and a second nozzle 12E. The first nozzle 11 is the same as in the embodiment described above.

[0067] The second nozzle 12E has a nozzle section 34E, which includes a first nozzle 34a, second nozzles 34b and 34c, and third nozzles 34d and 34e. The first nozzle 34a is located on the side of the first nozzle 11 opposite the shield surface 100, that is, above the first nozzle 11, and the second nozzles 34b and 34c are located on both sides of the first nozzle 11 in the left-right direction (width direction). The third nozzles 34d and 34e have a curved shape (fillet shape). The third nozzle 34d connects the first nozzle 34a and the second nozzle 34b, and the third nozzle 34e connects the first nozzle 34a and the second nozzle 34c. The other configurations are the same as in the embodiment described above.

[0068] Figure 14 is a front view showing a sixth modified example of the first and second nozzles.

[0069] In the sixth modified example, as shown in Figure 14, the shielding gas supply device 10F has a first nozzle 11F and a second nozzle 12F.

[0070] The first nozzle 11F has a semicircular shape and includes a nozzle portion 24F. The second nozzle 12F has a nozzle portion 34F, which includes a first outlet 34a. The first outlet 34a is located on the opposite side of the first nozzle 11F from the shield surface 100, that is, above the first nozzle 11. The first outlet 34a has a curved shape that follows the periphery of the semicircular first nozzle 11F. The other configurations are the same as those of the embodiment described above.

[0071] Figure 15 is a front view showing a seventh modified example of the first and second nozzles.

[0072] In the seventh modified example, as shown in Figure 15, the shielding gas supply device 10G has a first nozzle 11G and a second nozzle 12G.

[0073] The first nozzle 11G has a semicircular shape and includes a nozzle section 24G. The second nozzle 12G has a nozzle section 34G, which includes a first nozzle 34a and second nozzles 34b and 34c. The first nozzle 34a is located on the side of the first nozzle 11G opposite to the shield surface 100, that is, above the first nozzle 11. The second nozzles 34b and 34c are located on both sides of the first nozzle 11G in the left-right direction (width direction). The first nozzle 34a and the second nozzles 34b and 34c have a curved shape along the periphery of the semicircular first nozzle 11G. There is an intermittent section between the first nozzle 34a and the second nozzle 34b, and also an intermittent section between the first nozzle 34a and the second nozzle 34c. The other configurations are the same as in the embodiment described above.

[0074] Figure 16 is a front view showing an eighth modified example of the first and second nozzles.

[0075] In the eighth modified example, as shown in Figure 16, the shielding gas supply device 10H has a first nozzle 11H and a second nozzle 12H.

[0076] The first nozzle 11H has an elliptical shape and has a nozzle portion 24H. The second nozzle 12H has a nozzle portion 34H, and the nozzle portion 34H has a first outlet 34a. The first outlet 34a is located outside the first nozzle 11, excluding the portion adjacent to the shield surface 100 of the first nozzle 11H. The first outlet 34a has a curved shape along the periphery of the elliptical first nozzle 11H. The other configurations are the same as in the embodiments described above.

[0077] Figure 17 is a side view showing a ninth modified example of the first and second nozzles.

[0078] In the ninth modified example, as shown in Figure 17, the shielding gas supply device 10J has a first nozzle 11, a second nozzle 12, and a guide section 81.

[0079] The first nozzle 11 has a nozzle portion 24, and the nozzle portion 24 is formed with a curved surface such that the flow area gradually decreases toward the downstream side in the flow direction of the first shield gas G1. The second nozzle 12 is located outside the first nozzle 11 and has a nozzle portion 34, and the nozzle portion 34 is formed with a curved surface such that the flow area gradually decreases toward the downstream side in the flow direction of the second shield gas G2.

[0080] The guide section 81 is provided at the tip of the nozzle section 34 of the second nozzle 12. Therefore, the ejection position of the second shield gas G2 from the second nozzle 12 is downstream in the flow direction of shield gases G1 and G2 from the ejection position of the first shield gas G1 from the first nozzle 11. The guide section 81 has an inner flange and an outer flange of the ejection port of the second shield gas G2 from the second nozzle 12. However, the guide section 81 may consist only of the inner flange of the ejection port of the second shield gas G2 from the second nozzle 12, that is, only the flange between the ejection port of the first nozzle 11 and the ejection port of the second nozzle 12.

[0081] [Effects of this embodiment] The shield gas supply device according to the first embodiment includes a first nozzle 11 that ejects a first shield gas G1 along the shield surface 100 at a preset first velocity, and a second nozzle 12 that is located outside the first nozzle 11 and ejects a second shield gas G2 along the first shield gas G1 at a second velocity lower than the first velocity.

[0082] According to the shielding gas supply device of the first embodiment, the first nozzle 11 ejects the first shielding gas G1 along the shielding surface 100, and the second nozzle 12 ejects the second shielding gas G2 at a low speed to the outside of the first shielding gas G1. As a result, the second shielding gas G2 at a low speed takes in less ambient air. The first shielding gas G1 at high speed takes in more ambient second shielding gas G2, but because the second shielding gas G2 is an inert gas, the mixing of oxygen (air) into the first shielding gas G1 can be suppressed.

[0083] Therefore, the first shielding gas G1 flowing along the shield surface 100 becomes a gas that contains almost no oxygen, ensuring shielding performance against the processed surface. As a result, the shielding performance can be improved by suppressing the entrainment of ambient air into the first shielding gas G1.

[0084] Here, since the second nozzle 12 only needs to be able to eject a flow rate equivalent to the entrainment flow, the amount of first shielding gas G1 required can be reduced compared to enlarging the first nozzle 11 itself, thereby reducing running costs. Also, because the second flow velocity of the second shielding gas G2 ejected from the second nozzle 12 is low, the flow rate of ambient air taken into the jet of second shielding gas G2 ejected from the second nozzle 12 is also reduced, allowing the second nozzle 12 to be made smaller compared to enlarging the first nozzle 11.

[0085] The shield gas supply device according to the second embodiment is the same as the shield gas supply device according to the first embodiment, and furthermore, the second velocity is 1 / 5 or less of the first velocity. This suppresses the generation of entrainment flow by the low-speed second shield gas G2, suppresses the generation of vortices at the interface with the surrounding air, and allows for miniaturization of the second nozzle 12.

[0086] The third embodiment of the shield gas supply device is a shield gas supply device according to the first or second embodiment, further comprising a first nozzle 11 formed with a curved surface such that the flow path area gradually decreases toward the downstream side in the flow direction of the first shield gas G1. As a result, the first shield gas G1 ejected from the nozzle 24 can increase its first velocity without separating from the curved surface 45 of the upper wall 42. Consequently, the flow velocity of the first shield gas G1 can be made uniform, and turbulence (fluctuations) in the flow of the first shield gas G1 itself can be reduced.

[0087] The fourth embodiment of the shield gas supply device is a shield gas supply device according to the third embodiment, further comprising an upstream curved surface 45a that is convex outward on the upstream side in the flow direction of the first shield gas G1 and a downstream curved surface 45b that is convex inward on the downstream side in the flow direction of the first shield gas G1, with an inflection point P1 in the cross section passing through the center of gravity of the first nozzle 11 provided between the upstream curved surface 45a and the downstream curved surface 45b. By providing the upstream curved surface 45a and the downstream curved surface 45b having an inflection point P1, the flow velocity distribution at the nozzle outlet of the nozzle section 24 can be made uniform, and turbulence (fluctuation) in the flow of the first shield gas G1 can be reduced. In addition, by reducing the flow velocity deviation and turbulence of the first shield gas G1, mixing with the surrounding air can be suppressed, a smooth flow path shape can be formed, and the first nozzle 11 can be made smaller.

[0088] The fifth embodiment of the shield gas supply device is a shield gas supply device according to the third or fourth embodiment, wherein the second nozzle 12 has a rectangular outlet, and the inflection point P1 is positioned on the opposite side of the shield surface from the first nozzle 11. As a result, the velocity distribution of the first shield gas G1 when ejected from the outlet of the nozzle section 24 is made uniform, reducing turbulence in the flow of the first shield gas G1, and simplifying the nozzle section 24.

[0089] The shield gas supply device according to the sixth embodiment is a shield gas supply device according to the fifth embodiment, further comprising a second nozzle 12 having a first outlet 34a positioned on the side opposite to the shield surface 100 relative to the first nozzle 11, and second outlets 34b and 34c positioned on at least one side in the width direction of the first nozzle 11. This allows the second shield gas G2 to be ejected from the outside of the first nozzle 11, excluding the side facing the shield surface 100, surrounding the first shield gas G1, thereby reducing the supply amount of the first shield gas G1 and contributing to miniaturization of the second nozzle 12. Furthermore, since the distance from the shield surface 100 to the first outlet 34a is constant, a uniform effect of suppressing oxygen intrusion from the surroundings can be obtained for the first shield gas G1.

[0090] In the seventh embodiment of the shield gas supply device, the first nozzle 34a and the second nozzles 34b and 34c are connected by curved third nozzles 34d and 34e. This allows the direction of development of the velocity shear layer of the flow from the first nozzle 34a to the second nozzles 34b and 34c to change smoothly, suppressing discontinuities between adjacent velocity shear layers and bottom vortex flows. As a result, interference between the velocity shear layer and vortex flow of the second shield gas G2 from the first nozzle 34a and the second shield gas G2 from the second nozzle 34b can be suppressed.

[0091] The eighth aspect of the shield gas supply device is the same as the sixth aspect of the shield gas supply device, further provided with an inflection point located opposite the first nozzle 34a and the second nozzles 34b and 34c. As a result, the velocity distribution of the first shield gas G1 is made uniform at the position adjacent to the first nozzle 34a and the second nozzles 34b and 34c when it is ejected from the nozzle of the nozzle section 24, thereby reducing turbulence in the flow of the first shield gas G1.

[0092] The shield gas supply device according to the ninth embodiment is a shield gas supply device according to any one of the first to fifth embodiments, further wherein the second nozzle 12 is arranged parallel to the first nozzle 11. This allows for miniaturization by efficiently arranging the first nozzle 11 and the second nozzle 12, and also allows for the formation of a stable flow of the second shield gas G2 outside the first shield gas G1.

[0093] The shield gas supply device according to the tenth embodiment is a shield gas supply device according to any one of the first to sixth embodiments, further comprising: an upstream flow straightening mechanism (first mesh 64, honeycomb core 65, second mesh 66) arranged upstream of the curved surface in the flow direction of the first shield gas G1; and a downstream flow straightening mechanism (third mesh 67) arranged downstream of the curved surface in the flow direction of the first shield gas G1. As a result, the first shield gas G1 is straightened before being ejected to the outside along the shield surface 100, the velocity distribution when ejected from the nozzle section 24 is made uniform, and turbulence in the flow of the first shield gas G1 can be reduced.

[0094] The shield gas supply device according to the 11th embodiment is a shield gas supply device according to the 8th embodiment, further comprising a partition along the flow direction of the first shield gas G1, wherein the partition of the downstream straightening mechanism is thinner than that of the upstream straightening mechanism. This allows for appropriate reduction of turbulence in the flow of the first shield gas G1 ejected from the nozzle 24. In other words, since a thinner partition provides better straightening performance, it is possible to reduce turbulence in the first shield gas G1 ejected from the nozzle 24 onto the shield surface 100.

[0095] The shielding gas supply method according to the twelfth embodiment includes the steps of: ejecting a first shielding gas G1 along the shield surface 100 at a preset first velocity; and ejecting a second shielding gas G2 outside the first shielding gas G1 along the first shielding gas G1 at a second velocity lower than the first velocity. This makes it possible to improve shielding performance by suppressing the entrainment of ambient air into the first shielding gas G1.

[0096] In the embodiment described above, the first nozzle 11 and the second nozzle 12 are provided with connecting portions 21, 31, first bent portions 22, 32, second bent portions 23, 33, and nozzle portions 24, 34, but the configuration is not limited to this. The first nozzle 11 and the second nozzle 12 only need to have at least nozzle portions 24, 34.

[0097] Furthermore, although the shapes of the first nozzle 11 and the second nozzle 12 are rectangular in the embodiment described above, they may also be circular or other shapes. Also, although the ejection direction of the shielding gases G1 and G2 from the first nozzle 11 and the second nozzle 12 is horizontal, it may also be in a direction inclined with respect to the horizontal or in a vertical direction. Also, although the shield surface 100 is flat, it may be curved, in which case the shapes of the first nozzle 11 and the second nozzle 12 should be matched to the shape of the shield surface. [Explanation of Symbols]

[0098] 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10J Shielding gas supply device 11, 11F, 11G, 11H First Nozzle 12, 12A, 12B, 12C, 12D, 12E, 12F, 12G, 12H Second nozzle 21,31 Connection part 22,32 1st bending part 23,33 2nd bending part 24, 24F, 24G, 24H, 34, 34A, 34B, 34C, 34D, 34E, 34F, 34G Nozzle section 25,35 Supply pipe 34a,34a1,34a2 1st spout 34b,34c 2nd spout 34d,34e 3rd spout 41, 51 Lower wall 42, 52 Upper wall 43,44,53,54 side wall 45,55 Curved section 45a, 55a Upstream curved surface 45b, 55b Downstream curved surface 61 First guide vane 62 Perforated plate 63. Second guide vane 64. First Mesh (Upstream Flow Rectification Mechanism) 65. Honeycomb core (upstream flow rectification mechanism) 66. Second Mesh (Upstream Flow Rectification Mechanism) 67. Third Mesh (Downstream Flow Rectification Mechanism) 71 Guide vanes 72. Mesh No. 1 73 Second Mesh 81 Guide section 100 Shielding surface C11, C21 First channel C12, C22 Second channel C13, C23 Third channel C14, C24 4th channel G1 1st Shield Gas G2 Second Shield Gas P1,P2 inflection point

Claims

1. A first nozzle that ejects a first shielding gas at a preset first velocity along the shield surface, A second nozzle is positioned outside the first nozzle and ejects a second shielding gas along the first shielding gas at a second speed lower than the first speed, Equipped with, The second nozzle has an inner surface on the shield side that contacts the outer surface on the shield side of the first nozzle. Shielding gas supply device.

2. In the shielding gas supply device according to Claim 1, A process of ejecting a first shielding gas along the shield surface at a predetermined first velocity, A step of injecting a second shielding gas outside the first shielding gas at a second speed lower than the first speed along the first shielding gas, A shielding gas supply method having the following characteristics.

3. A first nozzle that ejects a first shielding gas at a preset first velocity along the shield surface, A second nozzle is positioned outside the first nozzle and ejects a second shielding gas along the first shielding gas at a second speed lower than the first speed, Equipped with, The first nozzle is formed with a curved surface such that the flow path area gradually decreases toward the downstream side in the flow direction of the first shield gas. The first nozzle has an upstream curved surface that is convex outward on the upstream side in the flow direction of the first shield gas, and a downstream curved surface that is convex inward on the downstream side in the flow direction of the first shield gas, and an inflection point is provided between the upstream curved surface and the downstream curved surface in a cross-section passing through the center of gravity of the first nozzle. The second nozzle has a rectangular outlet, and the inflection point is located on the side opposite to the shield surface relative to the first nozzle. Shielding gas supply device.

4. The second nozzle has a first nozzle outlet positioned on the side opposite to the shield surface relative to the first nozzle, and a second nozzle outlet positioned on at least one side in the width direction of the first nozzle. The shielding gas supply device according to claim 3.

5. The first nozzle and the second nozzle are connected by a third nozzle which has a curved shape. The shielding gas supply device according to claim 4.

6. The inflection point is provided at a position opposite the first nozzle and the second nozzle. The shielding gas supply device according to claim 4.

7. A first nozzle that ejects a first shielding gas at a preset first velocity along the shield surface, A second nozzle is positioned outside the first nozzle and ejects a second shielding gas along the first shielding gas at a second speed lower than the first speed, Equipped with, The first nozzle is formed with a curved surface such that the flow path area gradually decreases toward the downstream side in the flow direction of the first shield gas. The first nozzle has an upstream flow straightening mechanism positioned upstream of the curved surface in the flow direction of the first shield gas, and a downstream flow straightening mechanism positioned downstream of the curved surface in the flow direction of the first shield gas. Shielding gas supply device.

8. The upstream flow straightening mechanism and the downstream flow straightening mechanism each have a partition along the flow direction of the first shield gas, and the thickness of the partition of the downstream flow straightening mechanism is thinner than that of the partition of the upstream flow straightening mechanism. The shielding gas supply device according to claim 7.

9. The second speed is 1 / 5 or less of the first speed. A shielding gas supply device according to claim 3 or claim 7.

10. The second nozzle is arranged parallel to the first nozzle. A shielding gas supply device according to claim 3 or claim 7.

11. In the shielding gas supply device according to claim 3 or claim 7, A process of ejecting a first shielding gas along the shield surface at a predetermined first velocity, A step of injecting a second shielding gas outside the first shielding gas at a second speed lower than the first speed along the first shielding gas, A shielding gas supply method having the following characteristics.

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