Welding device and welding method

Abstract

This welding device (100) comprises an electron gun (21), control units (22, 23, 50) for controlling an electron beam, and a moving unit (30) for advancing the position of an irradiation point of the electron beam on a workpiece (T2) in a set first direction. The control units (22, 23, 50) scan the electron beam such that an irradiation point (P) of the electron beam on the workpiece (T2) vibrates in a reciprocating manner with a set amplitude and frequency, and adjusts the amplitude and the frequency so as to ensure a first condition under which the vibration speed of the irradiation point (P) is greater than the traveling speed of the irradiation point by means of the moving unit (30) in the first direction.

Description

Welding equipment and welding method

[0001] The present disclosure relates to a welding apparatus and a welding method.

[0002] Known welding devices for welding and joining workpieces include electric seam welding methods such as high-frequency welding and resistance welding, arc discharge welding methods such as TIG (Tungsten Inert Gas) welding and plasma welding, and energy beam welding methods such as laser beam welding and electron beam welding. Among these welding methods, for example, high-frequency welding allows for high welding speed but has poor power efficiency, while TIG welding has good power efficiency but a slow welding speed. Neither method achieves both high power efficiency and high welding speed. As a result, work efficiency decreases and the cost of the manufactured welded pipe increases. Given the need for both high power efficiency and high welding speed, energy beam welding has an advantage over other welding methods. For example, energy beam welding is also used when welding copper and copper alloy materials, which have high thermal conductivity and easily lose heat. Patent Document 1 discloses the following energy beam welding method for welding the ends of copper plates as workpieces using an energy beam.

[0003] In a conventional energy beam welding method, a copper or copper alloy strip is continuously drawn from a strip supply and formed into a slit tube with butted strip edges, which are then welded with a laser to produce a copper tube with a thin wall. The edge surface of the copper tube strip is roughened and wetted with a liquid hydrocarbon, combining these features, to enhance the introduction of laser energy to the strip edges. This allows the production of copper tube with a wall thickness of 0.2 mm and a welding speed of 20 m / min (see, for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2002-113586

[0005] In the energy beam welding method described in Patent Document 1, to prevent energy insufficiency when welding copper pipes with a pipe wall (metal plate thickness) of 0.2 mm, the edge surface of the copper pipe is roughened and wetted with liquid hydrocarbon to improve laser energy introduction. One factor that can cause energy insufficiency is that, in copper laser welding, the laser beam is strongly reflected by the shiny copper surface, resulting in insufficient heat input. Therefore, even when the above-described laser energy introduction improvement measures are taken, laser beam reflections can occur, resulting in insufficient heat input. In such cases, for example, when the copper pipe wall is thick, the laser beam penetration becomes shallow, leading to a decrease in the strength of the welded pipe produced by welding the copper pipe. In particular, Patent Document 1 produces welded pipes at a welding speed of 20 m / min. Generally, at higher welding speeds, the molten pool becomes unstable, resulting in welding defects such as undercuts and reduced weld quality. This further reduces the strength of the welded pipe itself.

[0006] The present disclosure discloses a technique for solving the above-mentioned problems, and aims to provide a welding device and a welding method that can ensure high welding quality regardless of the material, thickness, or welding speed of the workpiece.

[0007] The welding apparatus disclosed herein is a welding apparatus that joins workpieces by irradiating them with an electron beam, and includes: an electron gun that is provided in an envelope whose interior is maintained at a vacuum and that irradiates the electron beam onto the workpiece; a control unit that controls the electron beam irradiated from the electron gun; and a moving unit that moves the position of the irradiation point of the electron beam on the workpiece within the envelope in a set first direction, wherein the control unit performs vibration control that scans the electron beam so that the irradiation point of the electron beam on the workpiece oscillates back and forth with a set amplitude and frequency, and adjusts the amplitude and the frequency in the vibration control to ensure a first condition that the vibration speed of the irradiation point is greater than the traveling speed of the irradiation point in the first direction by the moving unit. The welding method disclosed herein is a welding method for joining workpieces by irradiating them with an electron beam from an electron gun, and includes an adjustment step of scanning the electron beam so that the position of the irradiation point of the electron beam on the workpiece oscillates back and forth with a set amplitude and frequency while moving the position of the irradiation point on the workpiece in a set first direction, and adjusting the amplitude and the frequency so that the oscillation speed of the irradiation point is greater than the traveling speed in the first direction.

[0008] The welding apparatus and welding method of the present disclosure provide a welding apparatus and welding method that can ensure high welding quality regardless of the material, thickness, or welding speed of the workpiece.

[0009] 2A is a diagram showing a schematic configuration of a welding apparatus according to embodiment 1. FIG. 2A is a perspective view showing a metal plate that is a material for a tubular body to be welded by the welding apparatus according to embodiment 1. FIG. 2B is a perspective view showing a tubular body formed by shaping a metal plate into a cylindrical shape. FIG. 2C is a perspective view showing a welded pipe manufactured by welding a tubular body ...C is a diagram showing a welded state of a tubular body when a control device of a welding apparatus according to this embodiment performs welding by standard control. FIG. 2C is a diagram showing a welded state of a tubular body when a control device of a welding apparatus according to this embodiment performs welding by vibration control. FIG. 2D is a diagram showing a welded state of a tubular body when a control device of a welding apparatus according to this embodiment performs welding by vibration control different from that of FIG. 4. FIG. 2D is a diagram showing another example of the configuration of a welding apparatus according to embodiment 1. FIG. 2D is a diagram showing a schematic configuration of a welding apparatus according to embodiment 2. FIG. 2E is a diagram showing an example of the hardware configuration of the control device of each embodiment. FIG. 2F is a diagram showing a schematic configuration of a welding apparatus according to embodiment 3. FIG. 2F is a diagram showing a welded state of a tubular body when a control device of a welding apparatus according to embodiment 3 performs welding by standard control. FIG. 2F is a diagram showing a welded state of a tubular body when a control device of a welding apparatus according to embodiment 3 performs welding by vibration control. 10A and 10B are diagrams illustrating the welding state of a tubular body when a control device of a welding device according to embodiment 3 performs welding by standard control, and the welding state of a tubular body when a control device of a welding device according to embodiment 3 performs welding by vibration control.

[0010] Embodiment 1. A welding apparatus 100 and a welding method according to an embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals. FIG. 1 is a diagram showing a schematic configuration of a welding apparatus 100 according to embodiment 1. The welding apparatus 100 performs welding by irradiating an electron beam to melt a workpiece to be welded. In this embodiment, as will be described in detail below, the welding apparatus 100 uses a cylindrical tubular body T2 made of metal as the workpiece to be welded, and irradiates the tubular body T2 with an electron beam to produce a welded pipe.

[0011] First, the tubular body T2 to be welded will be described with reference to the drawings. Fig. 2A is a perspective view showing a metal plate T1 that is the material for the tubular body T2 to be welded by welding device 100 according to embodiment 1. Fig. 2B is a perspective view showing a tubular body T2 obtained by forming the metal plate T1 shown in Fig. 2A into a cylindrical shape. Fig. 2C is a perspective view showing a welded pipe T3 produced by welding the tubular body T2 shown in Fig. 2B.

[0012] The Cartesian coordinate system XYZ shown in FIG. 2 is defined as follows: The welded pipe T3 is positioned so that the direction connecting one end of the cylindrical welded pipe T3 to the other end is horizontal. The X-axis is the horizontal direction connecting the two ends of the welded pipe T3, the Z-axis is the vertical direction perpendicular to the X-axis, and the Y-axis is the direction perpendicular to the X-axis and Z-axis. The arrows on the X-axis, Y-axis, and Z-axis are indicated as +X, +Y, and +Z, respectively, and the opposite directions are indicated as -X, -Y, and -Z. In the following description, the +Z direction may be referred to as the upside and the -Z direction as the downside. The drawings are schematic, and the dimensional relationships and ratios may differ between the drawings.

[0013] The metal plate T1 shown in FIG. 2A can be obtained, for example, by pulling out one end of a coiled strip of metal plate and unwinding it, and then cutting the pulled, straight strip of metal plate to a set length. The tubular body T2 shown in FIG. 2B can be obtained by butting the +Y-direction end and the −Y-direction end of the metal plate T1 shown in FIG. 2A together to form a cylindrical shape, so that the metal plate T1 is curved in the width direction (Y-axis direction). The butted portion where the circumferentially opposing ends of the metal plate T1 are joined is shown as a seam S. The welded pipe T3 shown in FIG. 2C can be obtained by irradiating the seam S of the tubular body T2 shown in FIG. 2B with an electron beam to melt the ends of the metal plate T1 and join the ends together.

[0014] The material of the metal plate T1 is preferably a metal with high thermal conductivity. For example, it may be a rolled copper or copper alloy plate. In this case, the tempering may be O-type, ½H-type, or ¼H-type as specified in JIS (Japanese Industrial Standards) H3100. The width of the metal plate T1 in the Y-axis direction may correspond to the outer diameter of the welded pipe T3 formed into a cylindrical shape. Furthermore, it is desirable that the width be the circumference calculated from the outer diameter of the welded pipe T3 plus the length of the weld allowance.

[0015] Although not shown, a groove may be formed on the upper surface of the metal plate T1 for the purpose of forming a groove in the inner peripheral wall of the welded pipe T3. This groove may be formed to extend in the longitudinal direction (X-axis direction) of the welded pipe T3 or in the width direction (Y-axis direction). This groove increases the contact area between the fluid flowing inside the welded pipe T3 and the welded pipe T3, allowing the welded pipe T3 to function as a refrigerant, resulting in more efficient heat exchange and improved performance of the final product. The thickness of the metal plate T1 is preferably equivalent to the thickness of the pipe wall of the welded pipe T3 formed into a tubular shape. The thickness of the metal plate T1 is preferably determined taking into account the fact that the metal plate T1 will become thinner when the groove is formed in the metal plate T1.

[0016] In the above-described welding, for example, when welding is performed using a laser beam when the metal plate T1 is made of copper or a copper alloy, the laser beam is strongly reflected by the surface of the tubular body T2, resulting in insufficient heat input energy. Therefore, if the wall thickness of the tubular body T2 is large or the welding speed is high, the penetration will be shallow, leading to a decrease in the strength of the welded pipe T3. Therefore, in order to ensure welding quality regardless of the material of the workpiece, the welding device 100 of the present disclosure uses an electron beam that does not cause beam reflection and does not result in insufficient heat input energy. Furthermore, to ensure welding quality regardless of the thickness of the workpiece or the welding speed, the electron beam is controlled as described below.

[0017] 1, a schematic configuration of a welding apparatus 100 will be described. The welding apparatus 100 includes a welding mechanism 40 and a control device 50 serving as a control unit for controlling the welding mechanism 40. The welding mechanism 40 includes an envelope 10 the interior of which is maintained under vacuum, an electron beam welder 20 housed within the envelope 10 and irradiating an electron beam, and a moving device 30 serving as a moving unit for moving a tubular body T2 within the envelope 10 in the X-axis direction.

[0018] The envelope 10 is configured to include a housing 1 having a first vacuum chamber 1V, and a housing 2 having a second vacuum chamber 2V disposed above the housing 1. A through-hole 1H is formed in the upper wall of the housing 1, and a through-hole 2H is formed in the lower wall of the housing 2. The through-holes 1H and 2H overlap in the vertical direction, connecting the first vacuum chamber 1V and the second vacuum chamber 2V.

[0019] The housing 1 has a supply hole 1IN on the −X direction side (upstream side) side wall for guiding the tubular body T2 to be welded from the outside into the first vacuum chamber 1V, and a discharge hole 1OUT on the +X direction side (downstream side) side wall for discharging the welded tubular body T2 to the outside. The tubular body T2 is supplied into the first vacuum chamber 1V through this supply hole 1IN by the moving device 30 with the seam S facing upward, and is sent from the −X direction side (upstream side) to the +X direction side (downstream side) through the through holes 1H and 2H, and is discharged to the outside of the first vacuum chamber 1V through the discharge hole 1OUT.

[0020] The supply hole 1IN may have a structure that seals the space between it and the tubular body T2 in order to ensure the degree of vacuum inside the envelope 10, or may have a structure that provides a vacuum chamber that reduces the difference in the degree of vacuum between the upstream side and the downstream side of the supply hole 1IN. Similarly, the discharge hole 1OUT may have a structure that seals the space between it and the tubular body T2, or may have a structure that provides a vacuum chamber that reduces the difference in the degree of vacuum between the upstream side and the downstream side of the discharge hole 1OUT.

[0021] The electron beam welding machine 20 includes an electron gun 21, a focusing coil 22 as a control unit, and a deflection coil 23 as a control unit. The electron gun 21 includes a cathode portion that generates an electron beam when a voltage is applied thereto, and an anode portion that accelerates the electron beam, both of which are not shown, and emits the electron beam downward. The focusing coil 22 converges the electron beam emitted from the electron gun 21. The deflection coil 23 deflects the electron beam emitted from the electron gun 21.

[0022] The control device 50 has operation control units 51, 52, and 53 that operate the electron gun 21, focusing coil 22, and deflection coil 23, respectively, and an overall control unit 55 that overall controls these operation control units 51, 52, and 53. The overall control unit 55 also has a memory device 56. In this manner, the control device 50 causes the electron gun 21 to generate an electron beam, emits the generated electron beam through the through holes 1H and 2H into the first vacuum chamber 1V, and scans the electron beam so that it collides with the seam S of the tubular body T2 in this first vacuum chamber 1V.

[0023] First, the welding state of the tubular body T2 when the control device 50 performs standard control to keep constant the voltage applied to the deflection coil 23 that deflects the electron beam will be described with reference to the drawings.

[0024] 3 is a diagram showing the welding state of the tubular body T2 when the control device 50 of the welding device 100 of this embodiment is performing standard control. In the figure, the area indicated by the dashed line centered on the irradiation point P, which is the irradiation position of the electron beam, is shown as viewed from above the tubular body T2.

[0025] In standard control, the control device 50 keeps the voltage applied to the deflection coil 23, which deflects the electron beam, constant. Therefore, the position of the irradiation point P of the electron beam within the first vacuum chamber 1V does not change. Meanwhile, as described above, the tubular body T2 is moved in the +X direction within the first vacuum chamber 1V by the movement device 30. Therefore, the irradiation point P of the electron beam on the tubular body T2 advances along the tubular body T2 toward the −X direction, which is the first direction, along the seam S of the tubular body T2, which extends in the X-axis direction. In this way, the electron beam is irradiated along the seam S of the tubular body T2 from the end of the tubular body T2 on the +X direction side to the end on the −X direction side.

[0026] When the electron beam is irradiated onto the joint S of the tubular body T2, the heat-input material of the tubular body T2 melts around the irradiation point P. Because the moving device 30 moves the tubular body T2 downstream in the +X direction, in the tubular body T2 during welding, the joint S is not welded on the upstream side of the irradiation point P in the -X direction, and a molten pool M, which is a puddle of molten metal formed by melting the metal material, is formed near the irradiation point P. Furthermore, a weld bead W, which is solidified metal from the molten pool M, is formed on the downstream side of the irradiation point P in the +X direction. The metal is in a liquid phase at a high temperature, forming the molten pool M, but as heat is released, the temperature drops and the metal changes from the liquid phase to a solid phase, resulting in the formation of the weld bead W.

[0027] Here, if the movement speed of the moving device 30 in the +X direction of the tubular body T2, i.e., the welding speed, is increased, the heat energy input to the tubular body T2 per unit area decreases even with the same output. This results in a smaller amount of molten metal or the metal does not reach the melting temperature. Therefore, if sufficient heat input energy is not ensured, the penetration depth will be shallow in areas where the welding speed is high. However, even if sufficient heat input energy is ensured, in areas where the welding speed is high, the time required for heat dissipation is longer than the time required for heat input, causing the temperature of the metal melted and turned into a liquid phase by the heat input to drop rapidly. This results in a larger temperature distribution within the molten pool M, which causes the shape of the molten pool M to become unstable. This in turn causes the shape of the weld bead W after the molten pool M solidifies to become unstable, resulting in poor welding quality, such as undercutting.

[0028] Undercut occurs when molten metal gathers at the center of the energy input, causing the center of the bead to protrude toward the electron beam irradiation source, i.e., in the +Z direction, and as a result, the bead ends in the +Y and -Y directions form depressions in the -Z direction. The high welding speed region is, for example, a welding speed of 10 m / min or more. Furthermore, even when the wall of the tubular body T2 is thick, the energy input to the tubular body T2 per unit area becomes small, which can similarly reduce the welding quality.

[0029] Therefore, in order to ensure high welding quality regardless of the thickness of the workpiece in the electron beam penetration direction or the welding speed, the welding device 100 of this embodiment can perform the following vibration control in addition to the above standard control.

[0030] Fig. 4 is a diagram showing the welding state of the tubular body T2 when the control device 50 of the welding device 100 of this embodiment performs welding using vibration control. Fig. 5 is a diagram showing the welding state of the tubular body T2 when the control device 50 of the welding device 100 of this embodiment performs welding using vibration control different from that shown in Fig. 4. In Figs. 4 and 5, the area indicated by the dashed line centered on the irradiation point P, which is the irradiation position of the electron beam, is shown as viewed from above the tubular body T2.

[0031] In the vibration control, the control device 50 changes the voltage waveform applied to the deflection coil 23 over time, for example, into a triangular wave, a sine wave, or the like, and scans the electron beam so that it reciprocates with set amplitudes A1 and A2 and frequency, with the seam S in the tubular body T2 as the vibration center of the irradiation point P of the electron beam, as shown in Figures 4 and 5. Furthermore, in this vibration control, the control device 50 adjusts the amplitude and frequency set in the reciprocating vibration so as to ensure a first condition that the vibration speed of the irradiation point P of the electron beam is faster than the welding speed, which is the moving speed of the irradiation point P in the -X direction by the moving device 30.

[0032] The oscillation speed of the electron beam is the displacement of the irradiation point P of the electron beam per unit time, and can be controlled by the amplitude, which is the oscillation width, and the frequency. The amplitude depends on the magnitude of the magnetic field generated in the deflection coil 23, and can be controlled by adjusting the magnitude of the current flowing through the deflection coil 23, etc. The frequency depends on the voltage waveform applied to the deflection coil 23. In other words, the frequency depends on the switching speed of the magnetic field generated in the deflection coil 23.

[0033] In addition, the control device 50 also adjusts the angle of the vibration direction of the electron beam in the vibration control. In the case shown in FIG. 4, the control device 50 adjusts the angle of the vibration direction of the electron beam relative to a direction parallel to the −X direction, which is the direction of travel of the electron beam's irradiation point P on the workpiece, to 0 degrees. In this case, the electron beam oscillates back and forth in the X-axis direction along the seam S. In the case shown in FIG. 5, the control device 50 adjusts the angle of the vibration direction of the electron beam relative to a direction parallel to the −X direction, which is the direction of travel of the electron beam's irradiation point P on the workpiece, to 90 degrees. In this case, the electron beam oscillates back and forth in the Y-axis direction, perpendicular to the seam S.

[0034] The angle of the electron beam vibration direction relative to a direction parallel to the -X direction, which is the direction of travel of the electron beam's irradiation point on the workpiece, is not limited to 0 degrees or 90 degrees as described above, but can be set arbitrarily within a range greater than 0 degrees and less than 90 degrees. Thus, the electron beam vibration direction, vibration amplitude, and frequency are parameters of the welding conditions. The control device 50 is configured to be able to switch between standard control, which does not vibrate the electron beam, and vibration control, which vibrates the electron beam. The welding process when the welding device 100 performs vibration control will be described below.

[0035] <Before Welding Starts> The control device 50 controls the operation of the electron gun 21 to be OFF, controls the focusing operation of the focusing coil 22 to be OFF, and controls the deflection operation of the deflection coil 23 to be OFF.

[0036] <At the start of welding> The control device 50 controls the focusing operation of the focusing coil 22 to the ON state, and controls the deflection operation of the deflection coil 23 to the ON state, thereby determining the path of the electron beam emitted from the electron gun 21. At this time, the control device 50 changes the voltage waveform applied to the deflection coil 23, and controls the deflection coil 23 so that the focused electron beam is in an oscillating state.

[0037] Furthermore, the control device 50 performs an adjustment process of adjusting the amplitude and frequency to be set so as to ensure the first condition that the vibration speed of the irradiation point P of the electron beam is greater than the welding speed. The welding speed used in this adjustment process may be stored in advance in the storage device 56 by the control device 50 as a database DB, or may be acquired by the control device 50 as needed from the moving device 30 via a control line (not shown).

[0038] Next, the control device 50 operates the cathode and anode of the electron gun 21 to emit an electron beam to the tubular body T2, whereby the electron beam having a vibration speed greater than the welding speed is irradiated with the joint S of the tubular body T2 as the vibration center.

[0039] As the moving device 30 moves the tubular body T2 in the +X direction, the electron beam is irradiated from the end of the tubular body T2 in the +X direction to the end of the tubular body T2 in the -X direction while vibrating around the joint S of the tubular body T2 as the vibration center. The operation of the deflection coil 23 to vibrate the electron beam in this manner continues from the welding start end, which is the irradiation start point of the tubular body T2, to the welding end end, which is the irradiation end point of the tubular body T2.

[0040] <At the end of welding> First, the control device 50 stops the operation of the electron gun 21 to stop the emission of the electron beam. Then, the control device 50 stops the focusing operation of the focusing coil 22 and the deflection operation of the deflection coil 23. By performing the welding method described above, the welding device 100 joins the ends of the metal plates T1 together and produces a welded pipe T3 having a weld bead W.

[0041] After the joint S is joined, the welded pipe T3 having the weld bead W is sent downstream to the +X side. This downstream process may include a process for annealing the welded pipe T3, a process for adjusting the outer and inner diameters of the welded pipe T3, and a process for recoiling the welded pipe T3. While FIG. 2 shows the tubular body T2 pre-cut to the desired length as the workpiece, the cutting process may be performed after the welded pipe T3 with the joint S joined is manufactured. In the above example, the tubular body T2 pre-formed into a cylindrical shape is guided into the first vacuum chamber 1V from the outside. However, a flat metal sheet T1 may be welded while being formed into the tubular body T2 in the first vacuum chamber 1V.

[0042] When vibration control, in which the electron beam is oscillated during welding, is performed as shown in Figures 4 and 5, the shape of the molten pool M is different compared to standard control, in which the electron beam is not oscillated, as shown in Figure 3. Generally, the end of the weld bead W often reflects the shape of the molten pool M. When the electron beam is oscillated, the molten pool M is characterized by an enlarged shape on the surface of the tubular body T2. This reduces the temperature distribution within the molten pool M, thereby stabilizing the shape of the molten pool M. While electron beam penetration generally tends to become shallower with increasing welding speed, the inventors' diligent efforts have confirmed that by achieving the first condition above, in which the electron beam oscillation speed is greater than the welding speed, sufficient heat input energy can be achieved, maintaining deep penetration and ensuring welding quality, even when the workpiece is thick in the direction of electron beam penetration or when the welding speed is high.

[0043] To satisfy the first condition above, that is, to make the oscillation speed of the electron beam faster than the welding speed, it is necessary to deflect the path of the electron beam at high speed. However, the welding device 100 of this embodiment does not use a reflecting mirror to deflect the electron beam as in the case of a laser beam, but instead switches the magnetic field generated by the deflection coil 23, thereby achieving high-speed deflection of the electron beam path. Therefore, the upper limit of the oscillation frequency can be made higher than when oscillating a laser beam, making it possible to control oscillation in a high-frequency range. This allows for a higher welding speed and ensures high productivity.

[0044] Furthermore, because the electron beam is vibrated rather than the workpiece, the vibration speed can be controlled with high precision, and the amplitude, vibration direction, and position of the irradiation point P in the X, Y, and Z axes can be easily changed. Furthermore, by vibrating the electron beam, convection in the molten metal is controlled, which also has the effect of reducing bubbles that occur in the weld metal. Because the vibration speed of the electron beam is greater than the welding speed, bubbles are quickly expelled from the molten metal.

[0045] Furthermore, as described above, the control device 50 adjusts the angle and amplitude of the electron beam oscillation direction relative to a direction parallel to the -X direction, which is the direction of travel of the electron beam irradiation point on the workpiece. Therefore, it is possible to irradiate the electron beam so that the molten pool M has a predetermined shape while ensuring the first condition. This allows for precise control of the size and shape of the molten pool M, making it possible to achieve, for example, circular sweeping. Controlling the size and shape of the molten pool M can prevent undercuts and other defects, improving welding quality, preventing a decrease in the strength of the welded pipe, and improving the reliability of the welded pipe.

[0046] Furthermore, the control device 50 can change at least the amplitude and frequency, among the amplitude, frequency, and angle of the electron beam vibration direction, as the irradiation point P moves in the first direction so that the molten pool M has a set shape while ensuring the first condition. For example, in a case where the thickness (tube wall) of the tubular body T2 in the beam penetration direction gradually increases or decreases, the amplitude can be gradually increased or decreased as the irradiation point P moves in the first direction while maintaining the amplitude that ensures the first condition. This makes it possible to adjust the shape of the molten pool M according to the state of the workpiece.

[0047] Furthermore, since the electron beam is irradiated inside the envelope 10, the inside of which is kept in a vacuum, no inert gas is required, and therefore oxidation of the welded portion can be suppressed.

[0048] Furthermore, as a result of the inventors' diligent efforts, it has been confirmed that welding quality can be further improved by ensuring the first condition and adjusting the amplitude of the electron beam so that it is greater than the thickness of the workpiece in the electron beam penetration direction. For example, when the plate thickness t is 0.4 mm and the welding speed is 10 m / min, it has been confirmed that the shape of the molten pool M can be stabilized when the beam oscillation speed is 12 times the welding speed or more and the beam oscillation width is 3 times the plate thickness or more. In this way, the amplitude of the electron beam is adjusted to an appropriate value depending on the wall thickness of the tubular body T2, within the range that ensures the first condition.

[0049] Next, a welding apparatus 100A having a different configuration from the welding apparatus 100 shown in FIG. 1 will be described. Components substantially identical to those of the welding apparatus 100 are designated by the same reference numerals, and their description will be omitted. FIG. 6 is a diagram showing the schematic configuration of the welding apparatus 100A according to the first embodiment. In the welding apparatus 100A, a moving device 30A serving as a moving unit capable of moving the electron beam welder 20 in the X-axis direction is disposed on the upper wall of the housing 2. In contrast, the moving device 30 for moving the tubular body T2 in the X-axis direction, which was provided in the welding apparatus 100 of FIG. 1, is not disposed within the housing 1, and the position of the tubular body T2 is fixed within the first vacuum chamber 1V. Therefore, the housing 1 does not have a supply hole 1IN for guiding the tubular body T2 into the first vacuum chamber 1V or a discharge hole 1OUT for discharging the tubular body T2 out of the first vacuum chamber 1V.

[0050] In the welding apparatus 100A configured in this manner, a tubular body T2 of a desired length is placed in the first vacuum chamber 1V, and after a sufficient degree of vacuum has been secured in the first vacuum chamber 1V, welding is performed with an electron beam. During welding, the position of the tubular body T2 is fixed, and the electron beam welder 20 is moved in the X-axis direction by the movement device 30A, and the electron beam is swept using vibration control. In this way, the electron beam is irradiated along the seam S of the tubular body T2 extending in the X-axis direction, from the end on the +X direction side of the tubular body T2 to the end on the -X direction side, thereby joining the seam S.

[0051] The moving unit that moves the relative positions of the workpiece and the electron gun can be either the moving device 30 that moves the tubular body T2 side, as shown in FIG. 1, or the moving device 30A that moves the electron beam welder 20 side, as long as it can advance the position of the electron beam irradiation point P on the workpiece in the -X direction. In the case of the moving device 30A that moves the electron beam welder 20 side, a transport mechanism for moving the tubular body T2 side is not required, thereby simplifying and miniaturizing the device. Furthermore, since the position of the tubular body T2 is fixed within the first vacuum chamber 1V, no positional shift occurs due to transport of the tubular body T2, which further improves the accuracy of adjusting the size and shape of the molten pool M. This further improves welding quality.

[0052] Next, a description will be given of welding apparatus 100B having a different configuration from welding apparatus 100A shown in Fig. 6. Fig. 7 is a diagram showing a schematic configuration of welding apparatus 100B according to embodiment 1. Welding apparatus 100B shown in Fig. 7 is configured by removing movement device 30A from welding apparatus 100A shown in Fig. 6, and by having the same configuration inside housing 2 as welding apparatus 100 shown in Fig. 1.

[0053] The welding apparatus 100B sweeps the electron beam by moving the oscillation center of the electron beam in the X-axis direction using a deflection coil 23 instead of the movement device 30A shown in FIG. 6 . That is, in the present welding apparatus 100B, the deflection coil 23 also functions as a movement unit that advances the position of the irradiation point of the electron beam in the X-axis direction. In this way, the electron beam is irradiated along the seam S of the tubular body T2 extending in the X-axis direction from the end on the +X-direction side of the tubular body T2 to the end on the -X-direction side, thereby joining the seam S. The present welding apparatus 100B also achieves the same effects as the welding apparatus 100A, and the apparatus configuration can be further simplified.

[0054] Although the above example shows welding and joining the butt ends of a single metal plate T1, the present invention is not limited to this. Since the welding device 100 is capable of welding while maintaining deep penetration without reducing the heat input energy, it is also possible to join, for example, two workpieces that overlap in the Z-axis direction.

[0055] The welding apparatus configured as described above is a welding apparatus that joins workpieces by irradiating them with an electron beam, and comprises: an electron gun that is provided in an envelope whose interior is maintained at a vacuum and that irradiates the workpiece with the electron beam; a control unit that controls the electron beam irradiated from the electron gun; and a moving unit that moves the position of the irradiation point of the electron beam on the workpiece within the envelope in a set first direction, wherein the control unit performs vibration control that scans the electron beam so that the irradiation point of the electron beam on the workpiece oscillates back and forth with a set amplitude and frequency, and adjusts the amplitude and the frequency in the vibration control to ensure a first condition that the vibration speed of the irradiation point is greater than the traveling speed of the irradiation point in the first direction by the moving unit.

[0056] In this way, the amplitude and frequency are adjusted to satisfy the first condition that the vibration speed of the irradiation point of the electron beam is greater than the moving speed of the irradiation point in the first direction by the moving part, so that even if the workpiece is made of copper, even if the pipe wall, which is the thickness of the workpiece in the electron beam penetration direction, is large, or even if the welding speed is high, high penetration depth and high welding quality can be ensured. Furthermore, because the welding speed can be increased, the productivity of welded pipes can be improved, leading to reduced costs.

[0057] Furthermore, in the welding apparatus configured as described above, the control unit adjusts the amplitude of the electron beam so that the first condition is ensured and the amplitude of the electron beam is greater than the thickness of the workpiece in the penetration direction of the electron beam.

[0058] In this way, the amplitude of the electron beam vibration is adjusted to a value that ensures that the vibration speed satisfies the first condition and is greater than the thickness of the workpiece in the direction of penetration of the electron beam, thereby ensuring high welding quality according to the thickness of the workpiece in the direction of penetration of the electron beam.

[0059] In the welding device configured as described above, the control unit adjusts at least the amplitude and the frequency of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction so that the first condition is ensured and a molten pool formed by irradiating the electron beam to melt the workpiece has a set shape. In the welding device configured as described above, the control unit changes at least the amplitude and the frequency of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction as the irradiation point moves in the first direction so that the first condition is ensured and the molten pool has a set shape.

[0060] In this way, at least the amplitude and frequency of the reciprocating vibration are adjusted so that the shape of the molten pool M has the desired shape while ensuring the first condition, thereby controlling the convection and heat conduction of the molten metal in the molten pool and ensuring even higher welding quality.

[0061] Embodiment 2. Hereinafter, embodiment 2 of the present disclosure will be described, focusing on the differences from embodiment 1 above. Portions similar to embodiment 1 above will be assigned the same reference numerals and description thereof will be omitted. Figure 8 is a diagram showing a schematic configuration of a welding device 200 according to embodiment 2. The welding device 200 of this embodiment includes a sensor 205 as a detection unit that detects the size of the gap between both ends of the metal plate T1 at the seam S of the tubular body T2. The size of the gap detected by the sensor 205 is transmitted to the control device 50 via a control line (not shown).

[0062] The control device 50 stores the amplitude, frequency, and vibration direction angle of the electron beam according to the size of the gap between the ends of the metal plates T1 as a database DB in the storage device 56 while ensuring the first condition. First, during welding by scanning the electron beam, the control device 50 acquires the size of the gap at the irradiation point P as needed using the sensor 205. The control device 50 selects, as needed, values ​​of the amplitude, frequency, and the angle of the vibration direction of the electron beam according to the acquired size of the gap from the storage device 56. Then, the control device 50 adjusts at least the amplitude and frequency out of the amplitude, frequency, and angle of the vibration direction of the electron beam as needed using the selected values, thereby applying heat input energy according to the size of the gap while ensuring the first condition.

[0063] The welding apparatus configured as described above comprises a detection unit that detects the size of the gap between the ends of the workpieces, and a database in which the amplitude, the frequency, and the angle of the vibration direction of the electron beam with respect to the first direction, which ensure the first condition, are recorded according to the size of the gap between the ends, and the control unit scans the electron beam so that the abutting portion of the ends of the workpieces vibrates back and forth with the irradiation point of the electron beam as the vibration center, acquires the size of the gap at the irradiation point from the detection unit as needed during the scanning of the electron beam, selects from the database as needed values ​​of the amplitude and frequency and the angle of the vibration direction of the electron beam with respect to the first direction, which values ​​correspond to the acquired size of the gap, and adjusts at least the amplitude and the frequency out of the amplitude, the frequency, and the angle of the vibration direction of the electron beam with respect to the first direction, using the selected values ​​as needed.

[0064] In this way, during welding, i.e., scanning the electron beam, the control unit continually acquires the size of the gap between the ends of the tubular body at the irradiation point and continually adjusts the amplitude and frequency to correspond to the acquired gap size. The adjusted amplitude and frequency are continually selected from those pre-recorded in a database according to the acquired gap size, enabling optimal adjustment based on prior simulations, experiments, etc. This ensures high welding quality even when the gap between the ends of the tubular body T2 varies across the X-axis.

[0065] An example of the hardware configuration of the control device 50 will be described below with reference to the drawings. FIG. 9 is a diagram showing an example of the hardware configuration of the control device 50 according to the present embodiment. The control device 50 is configured to include a processor 60 and a storage device 56. The storage device 56 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory, both not shown. Alternatively, a hard disk auxiliary storage device may be provided instead of the flash memory. The processor 60 executes a program input from the storage device 56. In this case, the program is input to the processor 60 from the auxiliary storage device via the volatile storage device. The processor 60 may output data such as calculation results to the volatile storage device of the storage device 56, or may store the data in the auxiliary storage device via the volatile storage device.

[0066] Embodiment 3. Hereinafter, embodiment 3 of the present disclosure will be described, focusing on the differences from embodiment 1 above. The same parts as embodiment 1 above will be assigned the same reference numerals and description thereof will be omitted. Figure 10 is a diagram showing the schematic configuration of a welding device 300 according to embodiment 3. The welding device 300 of this embodiment includes an image sensor 331 as a shape detection unit that acquires an image as shape data of the molten pool M on the tubular body T2.

[0067] The image sensor 331 may be provided inside the first vacuum chamber 1V or outside the envelope 10, and the installation location is not important as long as it can acquire shape data of the molten pool M. Furthermore, although the image sensor 331 that acquires images is exemplified as the shape detection unit, other sensors that acquire shape data other than images, such as an ultrasonic sensor, may also be used.

[0068] The control device 50 of this embodiment includes an image processing unit 354 as a control unit that performs arithmetic processing on the image acquired by the image sensor 331. Furthermore, the overall control unit 55 not only supervises the control of the operation control units 51, 52, and 53, but also supervises the control of the image processing unit 354. The welding process performed by the control device 50 based on the shape data acquired by the image sensor 331 will now be described.

[0069] Fig. 11 is a diagram showing the welding state of the tubular body T2 when the control device 50 of the welding device 300 of this embodiment performs welding by standard control. Fig. 12 is a diagram showing the welding state of the tubular body T2 when the control device 50 of the welding device 300 of this embodiment performs welding by vibration control.

[0070] 11 , when standard control is performed in which the voltage applied to the deflection coil 23 that deflects the electron beam is kept constant and the electron beam irradiation point P is not oscillated back and forth, the control device 50 acquires images as shape data from the image sensor 331 and detects the shape of the molten pool M in a liquid phase state using the image processing unit 354. Specifically, the image processing unit 354 detects a first length B1a of the molten pool M to both edges in the X direction parallel to the first direction, sandwiching the irradiation point P, when standard control is performed.

[0071] Next, the control device 50 performs vibration control, which changes the voltage applied to the deflection coil 23 that deflects the electron beam over time to scan the electron beam in a reciprocating oscillation, as shown in Fig. 12. At this time, the control device 50 adjusts the amplitude A1 so that a second length B1b of the molten pool M to both edges in the X direction across the irradiation point P during vibration control is greater than the first length B1a of the molten pool M during standard control.

[0072] In this way, by making the second length B1b of the molten pool M in the X direction along the welding direction greater than the first length B1a when the electron beam is not oscillated, it is possible to reduce the temperature difference inside the molten pool M, thereby achieving the effect of stabilizing the shape of the molten pool M. Furthermore, it is possible to reduce convection, which occurs due to the temperature difference inside the molten pool M and increases as the welding speed increases, and this convection effect can be used to prevent the shape of the molten pool M from being distorted and weld defects such as undercuts from occurring, thereby improving welding quality.

[0073] The control device 50 may adjust the amplitude A1 of the electron beam under vibration control so that it is larger than the first length B1a of the molten pool M under standard control. By performing such control, the second length B1b of the molten pool M in the X direction along the welding direction can be reliably made larger than the first length B1a when the electron beam is not oscillated, and the same effect as above can be stably obtained.

[0074] Although the above example shows the case where the electron beam is reciprocally oscillated parallel to the X direction along the welding direction, the control device 50 may also scan the electron beam as follows. Fig. 13 is a diagram showing the welded state of the tubular body T2 when the control device 50 of the welding device 300 of this embodiment performs welding using standard control. Fig. 14 is a diagram showing the welded state of the tubular body T2 when the control device 50 of the welding device 300 of this embodiment performs welding using vibration control.

[0075] As shown in Fig. 13, the control device 50 uses the image processing unit 354 to detect a first length B2a of the molten pool M during standard control, measured in the Y direction perpendicular to the X direction along the welding direction and sandwiching the irradiation point P. Next, as shown in Fig. 14, the control device 50 performs vibration control, scanning the electron beam so that it oscillates back and forth in the Y direction. At this time, the control device 50 adjusts the amplitude A2 so that a second length B2b of the molten pool M during vibration control, measured in the Y direction and sandwiching the irradiation point P, is greater than the first length B2a of the molten pool M during standard control. This type of control can also stabilize the shape of the molten pool M, reduce convection, and improve welding quality.

[0076] The control device 50 may adjust the Y-direction amplitude A2 of the electron beam during vibration control so that it is greater than the first Y-direction length B2a of the molten pool M during standard control. This ensures that the second Y-direction length B2b of the molten pool M is greater than the first Y-direction length B2a when the electron beam is not oscillated, thereby stably achieving the same effect as above.

[0077] In the above example, the image processing unit 354 detects the first length B1a in the direction parallel to the X direction across the irradiation point P and the first length B2a in the Y direction perpendicular to the X direction as the first length, but this is not limiting. The image processing unit 354 only needs to be able to detect shape data of the molten pool M, and therefore only needs to detect the length to the edge of the molten pool M spreading from the irradiation point P as the center. The control device 50 also adjusts the vibration angle with respect to the X direction during vibration control in accordance with the acquired length of the molten pool M.

[0078] In the above example, the control device 50 adjusts and sets the amplitude of the vibration control in advance based on the previously acquired shape of the molten pool M during standard control execution, but this is not limiting. The control device 50 can also use the image sensor 331 and the image processing unit 354 to detect the shape of the molten pool M as needed during vibration control execution, and adjust the amplitude of the electron beam as the irradiation point P moves in the first direction based on the detected shape of the molten pool M. In this way, by using the image sensor 331 and the image processing unit 354 to acquire the actual state of the molten pool M as needed and performing feedback control to adjust the amplitude based on that state, the shape of the molten pool M can be further stabilized.

[0079] Image sensor 331 shown in FIG. 10 may be attached to welding device 100A shown in FIG. 6 or welding device 100B shown in FIG. 7, and in this case too, the same effect as above can be achieved.

[0080] The welding apparatus configured as described above includes a shape detection unit that detects shape data of a molten pool formed by irradiating the workpiece with the electron beam, and the control unit adjusts the amplitude based on the shape data of the molten pool detected by the shape detection unit. In this way, by constantly acquiring the actual state of the molten pool and adjusting the amplitude based on that, the shape of the molten pool can be more stabilized.

[0081] In the welding apparatus configured as described above, the control unit detects from the shape data a first length of the weld pool to both edges of the irradiation point when standard control is performed, in which the irradiation point on the workpiece is not oscillated back and forth, and adjusts the amplitude of the vibration control so that a second length of the weld pool to both edges of the irradiation point when vibration control is performed is greater than the first length of the weld pool when standard control is performed. In this way, the first length, which represents the size of the weld pool, is made greater than the first length when the electron beam is not oscillated, and the amplitude of at least the reciprocating vibration is adjusted so that the weld pool has a predetermined shape while maintaining the first condition. This reduces the temperature difference within the weld pool and ensures a weld pool shape that effectively suppresses undercuts. Furthermore, the convection and heat conduction of molten metal within the weld pool can be controlled, ensuring even higher welding quality.

[0082] In the welding apparatus configured as described above, the control unit detects from the shape data a first length to both edges of the molten pool on either side of the irradiation point when standard control is performed in which the irradiation point of the electron beam on the workpiece is not oscillated back and forth, and adjusts the amplitude in the vibration control to be larger than the first length of the molten pool when standard control is performed. By such control, the first length, which is the size of the molten pool, can be reliably made larger than the first length when the electron beam is not oscillated, thereby stabilizing the shape of the molten pool and ensuring even higher welding quality.

[0083] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are anticipated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0084] Various aspects of the present disclosure are summarized below as appendices.

[0085] (Supplementary Note 1) A welding apparatus for joining workpieces by irradiating them with an electron beam, comprising: an electron gun provided in an envelope the interior of which is maintained at a vacuum and irradiating the workpiece with the electron beam; a control unit for controlling the electron beam irradiated from the electron gun; and a moving unit for moving a position of an irradiation point of the electron beam on the workpiece within the envelope in a set first direction, wherein the control unit scans the electron beam so that the irradiation point on the workpiece of the electron beam oscillates back and forth with a set amplitude and frequency, and adjusts the amplitude and the frequency to ensure a first condition in which the oscillation speed of the irradiation point is greater than the traveling speed of the irradiation point in the first direction by the moving unit. (Supplementary Note 2) The welding apparatus according to Supplementary Note 1, wherein the control unit adjusts the amplitude of the electron beam so that the first condition is ensured and the amplitude of the electron beam is greater than a thickness of the workpiece in a penetration direction of the electron beam. (Supplementary Note 3) The welding device according to Supplementary Note 2, wherein the control unit adjusts at least the amplitude and the frequency of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction so that the first condition is ensured and a molten pool formed by irradiating the workpiece with the electron beam has a set shape. (Supplementary Note 4) The welding device according to Supplementary Note 3, wherein the control unit changes at least the amplitude and the frequency of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction as the irradiation point moves in the first direction so that the first condition is ensured and the molten pool has a set shape.(Supplementary Note 5) The welding device according to any one of Supplementary Notes 1 to 4, comprising: a detection unit that detects the size of a gap between the ends of the workpieces; and a database in which the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction, which ensure the first condition, are recorded respectively according to the size of the gap between the ends, wherein the control unit: scans the electron beam so that the butted portion of the ends of the workpieces vibrates back and forth with the irradiation point of the electron beam as the oscillation center, acquires the size of the gap at the irradiation point from the detection unit as needed during the scanning of the electron beam, selects from the database as needed values ​​of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction, which values ​​correspond to the acquired size of the gap, and adjusts at least the amplitude and the frequency out of the amplitude, the frequency, and the angle of the oscillation direction of the electron beam with respect to the first direction using the selected values ​​as needed. (Supplementary Note 6) The welding device according to Supplementary Note 1 or Supplementary Note 2, wherein the control unit adjusts the angle of the oscillation direction of the electron beam with respect to a direction parallel to the first direction to be 0 degrees. (Supplementary Note 7) The welding device according to Supplementary Note 1 or Supplementary Note 2, wherein the control unit adjusts the angle of the oscillation direction of the electron beam with respect to a direction parallel to the first direction to be more than 0 degrees and less than 90 degrees. (Supplementary Note 8) The welding device according to Supplementary Note 1 or Supplementary Note 2, wherein the control unit adjusts the angle of the oscillation direction of the electron beam with respect to a direction parallel to the first direction to be 90 degrees. (Supplementary Note 9) The welding device according to any one of Supplementary Notes 1 to 8, wherein the movement unit moves the relative positions of the workpiece and the electron gun to advance the position of the irradiation point of the electron beam on the workpiece within the envelope in the first direction. (Supplementary Note 10) The welding device according to Supplementary Note 9, wherein the moving unit moves the electron gun in a direction opposite to the first direction, thereby moving a position of an irradiation point of the electron beam on the workpiece within the envelope in the first direction.(Supplementary Note 11) A welding method for joining workpieces by irradiating them with an electron beam from an electron gun, comprising: scanning the electron beam so that the position of an irradiation point of the electron beam on the workpiece oscillates back and forth with a set amplitude and frequency while moving the position of the irradiation point of the electron beam on the workpiece in a set first direction, and adjusting the amplitude and the frequency so that the oscillation speed of the irradiation point is greater than the propagation speed in the first direction. (Supplementary Note 12) The welding method according to Supplementary Note 11, comprising: butting ends of a single metal plate together to form a cylindrical tubular body as the workpiece; and oscillating the irradiation point of the electron beam back and forth with the butted portion of the ends of the circumferentially opposing metal plates as the oscillation center of the irradiation point of the electron beam to join the ends together.

[0086] 10 Envelope, 21 Electron gun, 22 Focusing coil (control unit), 23 Deflection coil (control unit), 30 Moving device (moving unit), 30A Moving device (moving unit), 50 Control device (control unit), 205 Sensor (detection unit), 100, 100A, 200, 300 Welding device, 331 Image sensor (shape detection unit), DB Database, T2 Tubular body (workpiece).

Claims

1. A welding device which joins workpieces by irradiating them with an electron beam, comprising: an electron gun which is provided within an envelope the interior of which is maintained in a vacuum and which irradiates the workpiece with the electron beam; a control unit which controls the electron beam irradiated from the electron gun; and a moving unit which advances the position of the irradiation point of the electron beam on the workpiece within the envelope in a set first direction, wherein the control unit executes vibration control which scans the electron beam so that the irradiation point on the workpiece of the electron beam oscillates back and forth with set amplitude and frequency, and adjusts the amplitude and frequency in the vibration control to ensure a first condition under which the vibration speed of the irradiation point is greater than the traveling speed of the irradiation point in the first direction by the moving unit.

2. The welding device according to claim 1, wherein the control unit adjusts the amplitude of the electron beam so that the first condition is ensured and the amplitude of the electron beam is greater than the thickness of the workpiece in the penetration direction of the electron beam.

3. The welding device as described in claim 2, wherein the control unit adjusts at least the amplitude and the frequency, and the angle of the vibration direction of the electron beam relative to the first direction, so that the first condition is ensured and a molten pool in which the workpiece is melted by irradiating the electron beam has a set shape.

4. The welding device described in claim 3, wherein the control unit changes at least the amplitude and the frequency, and the angle of the vibration direction of the electron beam relative to the first direction, as the irradiation point progresses in the first direction so that the first condition is ensured and the molten pool has a set shape.

5. A welding device as described in any one of claims 1 to 4, further comprising a shape detection unit that detects shape data of a molten pool formed when the workpiece is melted by irradiating the electron beam, and the control unit adjusts the amplitude based on the shape data of the molten pool detected by the shape detection unit.

6. The welding device described in claim 5, wherein the control unit detects from the shape data a first length of the molten pool to both edges of the irradiation point when standard control is executed in which the irradiation point of the electron beam on the workpiece is not vibrated back and forth, and adjusts the amplitude in the vibration control so that a second length of the molten pool to both edges of the vibration center of the irradiation point when the vibration control is executed is greater than the first length of the molten pool when the standard control is executed.

7. A welding device as described in claim 5 or claim 6, wherein the control unit detects from the shape data a first length to both edges of the molten pool on either side of the irradiation point when standard control is executed in which the irradiation point of the electron beam on the workpiece is not vibrated back and forth, and adjusts the amplitude in the vibration control so that it is greater than the first length of the molten pool when standard control is executed.

8. A welding device as described in claim 6 or claim 7, wherein the first length and a second length of the molten pool to both edges of the molten pool on either side of the vibration center of the irradiation point when the vibration control is performed are parallel to the first direction or perpendicular to the first direction on the surface of the workpiece.

9. A welding device as claimed in any one of claims 1 to 8, comprising: a detection unit which detects the size of a gap between the ends of the workpieces; and a database in which the amplitude, the frequency and the angle of the vibration direction of the electron beam with respect to the first direction, which ensure the first condition, are recorded according to the size of the gap between the ends, wherein the control unit scans the electron beam so as to vibrate back and forth around the butted portion of the ends of the workpiece with the electron beam irradiated with the point of irradiation of the electron beam as the center of vibration, obtains from the detection unit the size of the gap at the point of irradiation during the scanning of the electron beam, selects from the database values ​​of the amplitude, the frequency and the angle of the vibration direction of the electron beam with respect to the first direction according to the obtained size of the gap, and adjusts at least the amplitude and the frequency of the amplitude, the frequency and the angle of the vibration direction of the electron beam with respect to the first direction using the selected values.

10. The welding device according to claim 1 or 2, wherein the control unit adjusts the angle of the vibration direction of the electron beam with respect to a direction parallel to the first direction to be 0 degrees.

11. The welding device according to claim 1 or 2, wherein the control unit adjusts the angle of the vibration direction of the electron beam with respect to a direction parallel to the first direction so that the angle is greater than 0 degrees and less than 90 degrees.

12. The welding device according to claim 1 or 2, wherein the control unit adjusts the angle of the vibration direction of the electron beam with respect to a direction parallel to the first direction to be 90 degrees.

13. The welding device according to any one of claims 1 to 12, wherein the moving section moves the relative positions of the workpiece and the electron gun to advance the position of the irradiation point of the electron beam on the workpiece within the envelope in the first direction.

14. The welding device according to claim 13, wherein the moving unit moves the electron gun in a direction opposite to the first direction, thereby advancing the position of the irradiation point of the electron beam on the workpiece within the envelope in the first direction.

15. A welding method for joining workpieces by irradiating them with an electron beam from an electron gun, comprising the steps of: scanning the electron beam so that the position of the irradiation point of the electron beam on the workpiece oscillates back and forth with set amplitude and frequency while moving the position of the irradiation point on the workpiece in a set first direction; and adjusting the amplitude and frequency so that the vibration speed of the irradiation point is greater than the traveling speed in the first direction.

16. A welding method as claimed in claim 15, comprising butting ends of a single metal plate together to form a cylindrical tubular body as the workpiece, and joining the ends by reciprocatingly vibrating the irradiation point of the electron beam with the butted portion of the ends of the circumferentially opposing metal plates as the vibration center of the irradiation point of the electron beam.

Images