JP2013099793A - Welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding apparatus that can form a welding part having a high aspect ratio.SOLUTION: The welding apparatus includes: one electrode 11; the other electrode 12; and a first gas supply part 15 that supplies a first shielding gas from the circumference of a base material-side part of an arc region 13 formed between the one electrode 11 and a base material 20 connected to the other electrode 12 toward the center of the arc region 13, and controls the ratio of the pressure outside the arc region to the pressure at the center of the arc region 13 to within the range of 70 to 5000.

Description

  The present invention relates to a welding method.

  Conventionally, arc welding is used in the welding process.

  In arc welding, a welding current is supplied to one electrode and the other electrode, and a shielding gas is supplied between the electrode and the base material, whereby the shielding gas is ionized to form electrons having kinetic energy. The generated electrons form an arc region between one electrode and the base material. The electrons in the arc region collide with the base material, thereby giving kinetic energy to the base material and melting the base material.

  FIG. 1 is a view showing an arc welding apparatus according to a conventional example.

  The arc welding apparatus 100 includes a welding power source (not shown), one electrode 101 to which a welding current is supplied by the power source and the other electrode (not shown), and a cylinder that supplies a shielding gas toward the base material along the one electrode. Gas nozzle 102 is provided.

  When welding the base material, a welding current is supplied from the welding power source to the one electrode 101 and the other electrode, and a shield gas is supplied from the gas nozzle 102 so that the gap between the one electrode and the base material is reached. An arc region 103 is formed. The arc region 103 is crushed toward the base material by the pressure of the shielding gas supplied from above, and the contact portion with the base material is greatly expanded, so that the welding width W is increased. As described above, the arc region 103 has a bell-shaped shape of a lower blister.

  Therefore, in arc welding, since the energy density in the arc region at the contact portion with the base material is low, the penetration depth of the welded portion becomes shallow. That is, arc welding has a low aspect ratio, which is the ratio between the penetration depth of the weld and the welding width W. Therefore, arc welding is not suitable for welding that requires low distortion or high-speed welding, and is mainly used for welding with coarse accuracy.

  On the other hand, laser welding is used for welding that requires low distortion or high-speed welding. In laser welding, since the energy density of the melted portion is high, a weld portion having a high aspect ratio is formed.

JP-A-8-267250 JP 2003-53543 A Japanese Patent No. 2670076 Japanese Patent Laid-Open No. 11-241168

  However, laser welding has a problem that the cost of the welding apparatus is high.

  Further, arc welding includes plasma welding in which the energy density in the arc region is improved using a water-cooled contact tip.

  However, the plasma welding apparatus has a problem that the cost is higher than that of a normal arc welding apparatus. In addition, plasma welding has a problem in that it has an output limitation due to the influence of heat received by the contact tip.

  And in arc welding, the welding method which can form the weld part of a high aspect ratio using the welding apparatus which is not expensive has not been disclosed yet.

  In this specification, it aims at providing the welding method of the arc welding which solves the problem mentioned above.

  Another object of the present specification is to provide an arc welding welding apparatus that solves the above-described problems.

  The welding method of the first invention disclosed in the present specification includes a base of an arc region (13) formed between one electrode (11) and a base material (20) connected to the other electrode (12). The first shield gas is allowed to flow from the periphery of the material side portion toward the center of the arc region (13), and the ratio of the pressure at the center of the arc region (13) to the pressure outside the arc region is set to 70 or more and 5000 or less. And arc welding.

  Thereby, the base material side portion of the arc region is compressed from the surroundings by the pressure of the flow of the first shield gas, so that an arc region having a high ionization degree and a narrow width is formed. Since the base material is melted by the arc region having a high degree of ionization and a narrow width, a weld portion having a high aspect ratio is formed. In addition, by adjusting the flow rate of the first shield gas, or adjusting the nozzle diameter and nozzle height, the above pressure ratio range can be achieved, so that the welding method of the first invention can be implemented at low cost. It is.

  In the first invention described above, the arc region (13) formed between the one electrode (11) and the base material (20) connected to the other electrode (12) passes through the opening ( The first shield gas is allowed to flow from the base material side of the nozzle plate 14 having 14a) to the one electrode (11) side through the opening (14a), and the base material of the nozzle plate (14). Arc welding is preferably performed with the ratio of the pressure at the center of the arc region (13) on the side to the pressure outside the arc region being 70 or more and 5000 or less.

  As a result, the first shield gas can apply pressure from around the portion of the arc region on the base metal side, and can flow from between the opening and the arc region to one electrode side, so the width is narrow. In addition, the shape of the arc region having a high degree of ionization is stabilized.

  At this time, in the first invention described above, the ratio of the cross-sectional area of the arc region (13) passing through the opening (14a) to the area of the opening (14a) is 1 or more and 35 or less. Or the flow rate of the first shield gas through the opening (14a) is 5 liters / minute or more and 35 liters / minute or less, or the opening (14a) has a circular shape, The ratio of the diameter of the opening (14a) to the distance between the nozzle plate (14) and the base material (20) is preferably 1 or more and 20 or less.

  As a result, the first shield gas can apply pressure from the surroundings to the arc region and can flow from between the opening and the arc region to the one electrode side without damaging the arc region. The shape of the arc region which is narrow and has a high degree of ionization is more stable.

  In the first invention described above, it is preferable to flow the second shield gas from the one electrode (11) side toward the opening (14a). At this time, the ionization voltage of the second shield gas is preferably lower than the ionization voltage of the first shield gas, or the density of the first shield gas is preferably higher than the density of the second shield gas. . Thereby, the width | variety of an arc area | region can be narrowed and ionization degree can be raised further.

  Furthermore, in the first invention described above, the distance between the one electrode (11) and the other electrode (12) is increased while increasing the distance between the one electrode (11) and the base material (20). It is preferable to increase the voltage applied between the one electrode (11) and the other electrode (12) so that the flowing current becomes constant. At this time, when the voltage between the one electrode (11) and the other electrode (12) becomes larger than a predetermined threshold, the distance between the one electrode (11) and the base material (20) is increased. It is preferable to stop enlarging. Thereby, the amount of heat input is increased, and arc welding with improved energy density in the melted portion can be performed.

  The welding apparatus of the second invention disclosed in the present specification includes one electrode (11), the other electrode (12), and the mother connected to the one electrode (11) and the other electrode (12). The first shield gas is flowed from the periphery of the portion on the base material side of the arc region (13) formed with the material (20) toward the center of the arc region (13), and the center of the arc region (13) And a first gas supply unit (15) that sets the ratio of the pressure of the part and the pressure outside the arc region to 70 or more and 5000 or less.

  Thereby, the base material side portion of the arc region is compressed from the surroundings by the pressure of the flow of the first shield gas, so that an arc region having a narrow width and a high degree of ionization is formed. Since the base material is melted by the arc region having a high degree of ionization and a narrow width, a weld portion having a high aspect ratio is formed. Moreover, since the range of the pressure ratio mentioned above can be achieved by adjusting the flow rate of the first shield gas, the welding apparatus of the second invention can be manufactured at a low cost.

  In the welding apparatus of the second invention described above, an arc region (13) formed between the one electrode (11) and the base material (20) connected to the other electrode (12) passes therethrough. A nozzle plate (14) having an opening (14a) formed as described above, wherein the first gas supply unit (15) causes the first shield gas to flow to the base material side of the nozzle plate (14). The ratio of the pressure at the center of the arc region (13) on the base metal side of the nozzle plate (14) to the pressure outside the arc region is preferably 70 or more and 5000 or less.

  As a result, the first shield gas can apply pressure from around the portion of the arc region on the base metal side, and can flow from between the opening and the arc region to one electrode side, so the width is narrow. In addition, the shape of the arc region having a high degree of ionization is stabilized.

  In the second invention described above, the first gas supply section (15) includes a first gas supply pipe (15a) for supplying the first shield gas to the base material side of the nozzle plate (14), A first pressure sensor (15b) that measures the pressure at the center of the arc region (13) on the base metal side of the nozzle plate (14) and a pressure outside the arc region on the base material side of the nozzle plate (14). The second pressure sensor (15c), the measurement value of the first pressure sensor (15b) and the measurement value of the second pressure sensor (15c) are input, and the arc on the base material side of the nozzle plate (14) Control for controlling the amount of the first shield gas supplied to the first gas supply pipe (15a) so that the ratio between the pressure at the center of the region (13) and the pressure outside the arc region is 70 or more and 5000 or less. Part (15d). Arbitrariness.

  As a result, the first shield gas is allowed to flow to the base material side of the insulating plate, and the ratio of the pressure at the center of the arc region to the pressure outside the arc region on the base material side of the nozzle plate is set to 70 or more and 5000 or less. To be implemented.

  Moreover, it is preferable that the 2nd invention mentioned above is provided with the 2nd gas supply part (17) which flows 2nd shield gas toward the said opening part (14a) from the said one electrode (11) side.

  Thereby, for example, by appropriately selecting the ionization voltage or density of the first shield gas and the second shield gas, the width of the arc region can be narrowed to further increase the degree of ionization.

  Furthermore, the second invention described above includes a drive unit (21) for driving the one electrode (11) so as to change a distance between the one electrode (11) and the base material (20), and A drive control unit (22) for controlling the drive unit (21), and a power supply (16) for supplying a constant current between the one electrode (11) and the other electrode (12), The drive control unit (22) controls the drive unit (21) to increase the distance between the one electrode (11) and the base material (20), and the power source (16) The voltage applied between the one electrode (11) and the other electrode (12) is increased so that the current flowing between the one electrode (11) and the base material (20) is constant. It is preferable. At this time, the drive controller (22) drives the one electrode (11) when the voltage between the one electrode (11) and the other electrode (12) exceeds a predetermined threshold. It is preferable to control the drive unit (21) to stop. Thereby, the amount of heat input is increased, and arc welding with improved energy density in the melted portion can be performed.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a figure which shows the welding apparatus by a conventional example. (A) is sectional drawing which shows 1st Embodiment of the welding apparatus disclosed to this specification, (B) is a top view of FIG. 2 (A), (C) is FIG. ) Is an enlarged view of a main part surrounded by a chain line. (A) is an enlarged view of the principal part of FIG. 2 (A), (B) is a figure which shows the welding temperature distribution of a base material. It is a figure which shows the formula of the thermal ionization of Saha. It is a figure which shows the relationship between temperature and an ionization degree. It is a figure which shows distribution of the ionization degree of the shielding gas in an arc area | region. It is a figure which shows the relationship between a pressure ratio and an ionization degree. It is a figure (the 1) which shows the relationship between a pressure ratio and an aspect ratio. It is a figure (the 2) which shows the relationship between a pressure ratio and an aspect ratio. It is a figure which shows 2nd Embodiment of the welding apparatus disclosed to this specification. It is a figure which shows the ionization voltage and density of shielding gas. It is a figure which shows 3rd Embodiment of the welding apparatus disclosed to this specification. It is a figure explaining the relationship between the displacement amount of one electrode, a voltage, and an electric current. It is a figure which shows the arc area | region in the time t1 and t3 of FIG. It is a figure which shows the other example of the welding apparatus disclosed by this specification. It is a figure which shows the other example of the welding apparatus disclosed by this specification. It is a figure which shows the YY sectional view taken on the line of FIG. It is a figure which shows the ZZ sectional view taken on the line of FIG. It is a figure which shows the welding result of an Example and a comparative example.

  Hereinafter, a preferred embodiment of a welding apparatus disclosed in the present specification will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the invention described in the claims and equivalents thereof.

  2A is a cross-sectional view illustrating a plan view of the first embodiment of the welding apparatus disclosed in this specification, and FIG. 2B is a top view of FIG. 2A. FIG. 3C is an enlarged view of a main part surrounded by a chain line in FIG. 3A is an enlarged view of the main part of FIG. 2A, and FIG. 3B is a diagram showing a welding temperature distribution of the base material.

  The welding apparatus 10 of the present embodiment forms an arc region with a narrow width and a high degree of ionization by flowing a shielding gas from the periphery of the base material side portion of the arc region toward the center of the arc region. A weld with a high aspect ratio is formed by melting the base material in an arc region having a narrow width and a high degree of ionization.

  In the welding apparatus 10, an arc region 13 formed between one rod-like electrode 11, the other electrode 12, and the base material 20 connected to the one electrode 11 and the other electrode 12 passes therethrough. A nozzle plate 14 having a circular opening 14a formed on the nozzle plate 14 and flowing a first shield gas to the base material side of the nozzle plate 14, and the pressure at the center of the arc region 13 on the base material side of the nozzle plate 14; A first gas supply unit 15 that adjusts the ratio of the pressure outside the arc region to 70 or more and 5000 or less.

  Further, the welding apparatus 10 includes a housing 18 that supports a cylindrical base material 20. The housing supports the cylindrical base material 20 in a rotatable manner. The base material 20 is rotated by a driving device (not shown). As shown in FIG. 2A, the nozzle plate 14 is disposed at the center of the housing 18. The nozzle plate 14 may be formed as a part of the housing 18.

  An electrical insulating material 19 is disposed between the housing 18 and the base material 20, and the housing 18 and the base material 20 are electrically insulated. The electrical insulating material 19 seals the cylindrical base material 20 rotatably between the housing 18 and the base material 20 to prevent the shield gas from flowing out of the gap. FIG. 2A is a cross-sectional view taken along line XX in FIG. Moreover, in FIG. 2 (A) and FIG. 2 (B), the 1st pressure sensor 15b and the 2nd pressure sensor 15c which are mentioned later are not described.

  As shown in FIG. 3A, the first gas supply unit 15 includes a first gas supply pipe 15 a that supplies the first shield gas to the base material side of the nozzle plate 14, and an arc on the base material side of the nozzle plate 14. The first pressure sensor 15b that measures the pressure at the center of the region 13, the second pressure sensor 15c that measures the pressure outside the arc region on the base material side of the nozzle plate 14, and the measured values of the first pressure sensor 15b And the measurement value of the second pressure sensor 15c is input so that the ratio of the pressure at the center of the arc region 13 on the base material side of the nozzle plate 14 to the pressure at the position outside the arc region is 70 or more and 5000 or less. And a controller 15d for controlling the amount of the first shield gas supplied to the first gas supply pipe 15a. Hereinafter, the ratio between the pressure at the center of the arc region 13 on the base material side of the nozzle plate 14 and the pressure at a position outside the arc region is also simply referred to as a pressure ratio.

  As shown in FIG. 2A, the first gas supply unit 15 has four first gas supply pipes 15a. Each of the first gas supply pipes 15 a is piped to the housing 18. The first shielding gas passes through the four first gas supply pipes 15 a and then passes between the housing 18 and the base material 20 and is supplied to the base material side of the nozzle plate 14. The first shield gas is ionized to form the arc region 13. The first shield gas shields the molten weld from the atmosphere.

  The opening 14 a is formed at the center of the electrically insulating nozzle plate 14. One electrode 11 is disposed so as to be positioned at the center of the opening 14a. The arc region 13 formed between one electrode 11 and the base material 20 is located at the center of the opening 14a.

  The first shield gas supplied into the housing 18 through the first gas supply pipe 15 a is prevented from flowing outside the housing 18 by the electrical insulating material 19. Therefore, the first shield gas supplied into the housing 18 passes from the base material side of the nozzle plate 14 to the one electrode 11 side through the opening 14a. The first shield gas that has escaped to the one electrode 11 side of the nozzle plate 14 may be exhausted by an exhaust unit (not shown).

  As shown by an arrow in FIG. 2C, the first shielding gas supplied to the base material side of the nozzle plate 14 through the first gas supply pipe 15a is around the base material side portion of the arc region 13. To the center of the arc region 13. Thus, since the arc region 13 that has received the pressure of the first shield gas from the periphery is compressed in the direction of the center portion, a narrow arc region 13 having a high degree of ionization is formed.

  In the present specification, the portion of the arc region 13 on the base material side is larger than half of the length of the arc region 13 formed between one electrode 11 and the base material 20 connected to the other electrode 12. A portion on the material side is preferable, and in particular, a portion on the base material side with respect to one third of the length of the arc region 13 is preferable.

  Further, the first shield gas may be flowed into the arc region 13 together with the part on the base material side of the arc region 13 and the part on the one electrode side of the arc region 13. The height at which the first shield gas flows with respect to the arc region 13 can be changed by adjusting the distance h between the nozzle plate 14 and the base material 20.

  The first pressure sensor 15b can be fixed at the center position of the arc region 13 by a known method. The second pressure sensor 15c can be fixed to the surface of the nozzle plate 14 on the base material side by a known method.

  The control unit 15d inputs the measurement value of the first pressure sensor 15b and the measurement value of the second pressure sensor 15c, and supplies the first shield gas to the first gas supply pipe 15a so that the pressure ratio becomes 70 or more and 5000 or less. Control the amount supplied.

  As a method for controlling the pressure ratio by the control unit 15d, a known control method can be used. As a control method, for example, feedback control can be used. In this feedback control, the ratio between the measured value of the first pressure sensor 15b and the measured value of the second pressure sensor 15c is the current pressure ratio, and the difference between the current pressure ratio and the target pressure ratio is zero. As described above, the amount of the first shield gas supplied to the first gas supply pipe 15a is controlled.

  The first pressure sensor 15b and the second pressure sensor 15c preferably have heat resistance against the temperature of the arc region 13.

  The control unit 15d inputs the measurement value of the first pressure sensor 15b and the measurement value of the second pressure sensor 15c continuously or at predetermined intervals, and the first shield so that the pressure ratio becomes 70 or more and 5000 or less. You may make it control the quantity which supplies gas to the 1st gas supply pipe | tube 15a.

  In addition, the control unit 15d determines the amount of the first shield gas to be supplied to the first gas supply pipe 15a using the first pressure sensor 15b and the second pressure sensor 15c only when the welding condition is changed, Thereafter, unless the welding conditions are changed, the first shield gas is supplied to the first gas supply pipe 15a using the determined supply amount of the first shield gas without using the first pressure sensor 15b and the second pressure sensor 15c. May be supplied. In this way, the first pressure sensor 15b and the second pressure sensor 15c are arranged in the arc region 13 or at the base metal side of the nozzle plate 14 only when measuring the pressure, and when the pressure is not measured. In addition, it does not have to be disposed in the arc region 13 or at the position on the base material side of the nozzle plate 14.

  The amount of the first shield gas supplied to the first gas supply pipe 15a may be determined so that the pressure ratio is 70 or more and 5000 or less without arc discharge. The amount of the first shield gas supplied to the first gas supply pipe 15a may be determined using a calculation such as a heat conduction analysis simulation.

  In addition, the welding apparatus 10 includes a welding power source 16 that supplies a welding current to one electrode 11 and the other electrode 12. The welding power source 16 can supply a direct current or an alternating current to each electrode. In addition, the welding power source 16 can supply a continuous current or a pulse current to each electrode. When supplying a direct current to each electrode, the welding power source 16 supplies the welding current so that one electrode 11 serves as a cathode and the other electrode 12 serves as an anode.

  One electrode 11 and the nozzle plate 14 are supported by a support portion (not shown) so as not to contact the base material 20.

  2 does not show the control unit 15d, the welding power source 16, and the base material 20 shown in FIG.

  The base material 20 may have various joint forms depending on the form to be joined. As a forming material of the base material 20, for example, a metal such as stainless steel or alloy steel, or a non-ferrous metal such as copper or aluminum can be used. The weld joint may have, for example, the form of a butt joint, groove joint, lap joint or fillet joint. Moreover, the welding apparatus 10 may have a welding wire or welding rod (not shown) and means for supplying these wires or rods to the welded portion. As a material for forming the electrode 11, for example, tungsten containing cerium, tungsten containing thorium, tungsten containing lantana, or the like can be used.

  The shape of the arc region formed by the conventional arc welding apparatus is shown by a chain line in FIG. The arc region formed by the conventional welding apparatus has a bell-shaped shape of a lower blister.

  On the other hand, as for the shape (solid line) of the arc area | region 13 formed with the welding apparatus 10, as shown to FIG. 3 (A), the width | variety of an arc area | region has narrowed. As compared with the conventional shape, the arc region 13 has a narrower width especially on the base material side, and has a columnar vertically long shape as a whole.

  Thus, since the arc region 13 formed by the welding apparatus 10 has a small width at the contact portion with the base material, the welding width W is also small. Therefore, in the welding apparatus 10, an arc region 13 having a narrow width and a high degree of ionization is formed.

  FIG. 3B shows a relationship (solid line) between the position on the base material to be welded by the welding apparatus 10 and the temperature of the base material. FIG. 3B shows the relationship (chain line) between the position on the base material welded by the conventional arc welding apparatus and the temperature of the base material. The distribution of the welding temperature on the base material arc-welded by the welding apparatus 10 is narrower and the temperature is higher than the conventional temperature distribution.

  Next, the reason why the welding apparatus 10 performs arc welding by setting the ratio of the pressure at the center of the arc region to the pressure outside the arc region to 70 to 5000 will be described.

  The arc region 13 is in a plasma state in which gas molecules forming the shield gas are ionized, and electrons, ionized gas molecules, and neutral gas molecules that are not ionized are mixed. The relationship between the ionization degree of the ionized plasma state, the pressure, and the temperature can be expressed by Saha's thermal ionization equation.

  FIG. 4 is a diagram illustrating the Saha thermal ionization equation.

  Here, x represents the degree of ionization, which is the ratio of ionized gas molecules, P represents pressure, A represents a constant, T represents absolute temperature, e represents the elementary charge, and Vi represents the amount of gas molecules. Indicates an ionization voltage, and k indicates a Boltzmann constant.

  FIG. 5 is a diagram showing the relationship between temperature and degree of ionization.

  As shown in FIG. 5, in the plasma state, the ionization degree x of the gas molecules increases as the temperature increases, and the rate of increase in temperature decreases as the ionization degree approaches 1.

  FIG. 6 is a diagram showing the distribution of the ionization degree of the shielding gas in the arc region. The distribution of the ionization degree of the shielding gas in the arc region shown in FIG. 6 was obtained as follows. First, calculate the temperature distribution in the arc region by calculation of thermoelectric analysis, etc., and then substitute the calculated temperature in the arc region into Saha's thermoionization formula to distribute the ionization degree of the shielding gas in the arc region Got.

  As shown in FIG. 6, the closer to the center of the arc region, the higher the ionization degree of the gas molecules. On the other hand, the ionization degree of gas molecules decreases as the distance from the center of the arc region increases.

  On the other hand, it can be seen from the relationship between the degree of ionization and the temperature shown in FIG. 5 that the degree of ionization at which a welding temperature necessary for melting the base material is obtained is 0.016 or more. Therefore, in the ionization degree distribution in the arc region shown in FIG.

  Further, from the relationship between the temperature and the degree of ionization shown in FIG. 5, it can be seen that the degree of ionization increases rapidly with increasing temperature from around 11000K. Therefore, FIG. 7 shows the result of summarizing the relationship between the pressure ratio at 11000 K and the degree of ionization.

  FIG. 7 is a diagram showing the relationship between the pressure ratio and the degree of ionization.

  In conventional arc welding, the ionization degree is 0.016 or more. From FIG. 7, the pressure ratio at which the degree of ionization is 0.016 is 1.

  It has also been found that when the degree of ionization is about 0.0019, the plasma temperature necessary for arc welding cannot be obtained. From FIG. 7, the pressure ratio at which the degree of ionization is 0.0019 is 70.

  Accordingly, it can be seen that by increasing the pressure ratio of the portion where the ionization degree in the arc region shown in FIG. 6 is 0.016 or more to 70 times or more, the pressure ratio becomes 70 or more and the ionization degree can be 0.0019 or less. As a result, an arc region having a high degree of ionization and a narrow width can be obtained.

  Here, the position at which the pressure at the center of the arc region is measured is preferably vertically below the center of one of the electrodes. Moreover, it is preferable that the position which measures the pressure of the center part of an arc area | region is a part by the side of the base material of an arc area | region.

  Further, the position for measuring the pressure outside the arc region may be a position near the arc region or may be separated from the arc region as long as it is a region on the base material side of the nozzle plate 14. Furthermore, the position for measuring the pressure outside the arc region may be the region on the one electrode 11 side of the nozzle plate 14.

  Further, the outside of the arc region is preferably a portion having a distance from the arc region 13 that is 1/2 of the ionization region width L of the arc region 13, particularly 1/3 or less.

  FIG. 8A is a diagram (part 1) illustrating a relationship between a pressure ratio and an aspect ratio.

  FIG. 8A shows a relationship between an aspect ratio and a pressure ratio, which is a ratio between a penetration depth and a welding width of a welded portion obtained by arc-welding a base metal using the welding apparatus shown in FIGS. It is what I have sought.

  In the arc welding experiment, the welding current is 50 A, the flow rate of the shielding gas is 5 to 25 liters / minute, the distance between one electrode and the base material is 1 mm, and the diameter of the opening Was 3 mm, the forming material of one electrode was tungsten containing cerium, and the forming material of the base material was stainless steel. In FIG. 8A, data with a pressure ratio of 100 or less was obtained by experiments. In addition, the aspect ratio was calculated as a ratio between the penetration depth and the width by measuring the penetration depth of arc welding and the width of the welded portion. In FIG. 8A, data having a pressure ratio of 500 or more was obtained by calculation. In the calculation, the gas flow was analyzed by simulation to determine the gas distribution that affects the shape of the arc region. The calculation conditions used were the same as in the arc welding experiment described above. In FIG. 8A, some plots show the pressure ratio values.

  In FIG. 8A, the range of the pressure ratio is roughly divided into three. In the region R1, since the pressure ratio is small, the width of the arc region is widened, so the aspect ratio is small. In the region R3, since the pressure ratio is large, the flow of the shield gas is disturbed and the discharge becomes unstable. In some cases, the discharge is stopped, so that the aspect ratio becomes small. In the region R2, a stable arc discharge is formed and a narrow arc region is formed, so that a high aspect ratio can be obtained. Thus, it can be seen that arc welding is preferably performed in the range of the pressure ratio of the region R2. Specifically, the following knowledge was obtained as the pressure ratio in the region R2.

  Since this pressure ratio is 70 or more, an arc region having a narrow width and a high degree of ionization is stably formed. The pressure ratio described above is preferably 100 or more, particularly 200 or more from the viewpoint of obtaining an arc region having a narrower width and a higher ionization degree.

  Moreover, when this pressure ratio is 5000 or less, an arc region having a narrow width and a high degree of ionization is stably formed. Further, the pressure ratio is preferably 3000 or less, particularly 1000 or less from the viewpoint of obtaining an arc region having a narrower width and a higher ionization degree.

  Next, the preferable structure of the welding apparatus 10 for forming the shape of an arc area | region with a narrow width | variety and high ionization degree is further demonstrated below.

  First, the ratio of the cross-sectional area of the portion of the arc region 13 passing through the opening 14a and the area of the opening 14a is preferably 1 or more and 35 or less. By setting the area ratio in such a range, the first shield gas applies pressure to the arc region from the surroundings, and does not impair the arc region, so that it does not damage the arc region from the opening to the one electrode side. Since it can flow, the shape of the arc region having a narrow width and high ionization degree is more stable.

  The flow rate of the first shield gas passing through the opening 14a is preferably 5 liters / minute or more and 35 liters / minute or less. By setting the flow rate of the first shield gas in such a range, the first shield gas applies pressure to the arc region from the surroundings and does not impair the arc region. Since it can flow to the electrode side, the shape of the arc region having a narrow width and high ionization degree is more stable.

  Furthermore, the ratio of the cross-sectional area of the portion of the arc region 13 passing through the opening 14a and the area of the opening 14a is preferably 1 or more and 35 or less. By setting the distance ratio in such a range, the first shielding gas applies pressure to the arc region from the surroundings, and from the gap between the opening and the arc region to one electrode side so as not to damage the arc region. Since it can flow, the shape of the arc region having a narrow width and high ionization degree is more stable. Specifically, the diameter d of the opening 14a is preferably 5 mm or less, and the distance between the nozzle plate 14 and the base material 20 is preferably 2 mm or less.

  FIG. 8B is a diagram (part 2) illustrating a relationship between a pressure ratio and an aspect ratio. 8B, the distance h between the nozzle plate 14 and the base material 20 is 0.3 mm, and the □ mark plot is the distance h between the nozzle plate 14 and the base material 20 being 0. 6 mm.

  The aspect ratio shown in FIG. 8B was obtained as a ratio between the penetration depth and the width by measuring the penetration depth obtained by arc-welding the base metal and the width of the welded portion using the welding apparatus shown in FIGS. Further, in this arc welding, the welding current is 40 A, the flow rate of the shielding gas is 10 to 20 liters / minute, the distance between one electrode and the base material is 1 mm, The diameter was 3 mm, the forming material of one electrode was tungsten containing cerium, and the forming material of the base material was stainless steel.

  As shown in FIG. 8B, it can be seen that when the diameter d of the opening 14a is constant, a higher aspect ratio is obtained when the distance h between the nozzle plate 14 and the base material 20 is shorter. This is presumably because the shorter the distance h between the nozzle plate 14 and the base material 20 is, the more stable the shape of the arc region having a narrow width and high ionization degree is formed. It can also be seen that the aspect ratio increases as the pressure ratio increases.

  According to the welding apparatus 10 of the present embodiment described above, the portion on the base material side of the arc region is compressed from the surroundings by the pressure of the flow of the first shield gas, so that an arc region with a high ionization degree and a narrow width is formed. It is formed. Since the base material is melted by the arc region having a high ionization degree and a narrow width, a weld portion having a high aspect ratio is formed. In addition, by adjusting the flow rate of the first shield gas and designing the nozzle diameter and nozzle height, the pressure ratio range described above can be achieved, so that the welding apparatus can be manufactured at low cost. .

  Next, 2nd-3rd embodiment of the welding apparatus mentioned above is described below, referring FIGS. 9-14. For points that are not particularly described in the second embodiment, the description in detail regarding the first embodiment is applied as appropriate. Moreover, the same code | symbol is attached | subjected to the same component.

  FIG. 9 is a diagram illustrating a second embodiment of the welding apparatus disclosed in this specification.

  The welding apparatus 10 according to the present embodiment includes a second gas supply unit 17 that allows the second shield gas to flow from the one electrode 11 side toward the opening 13. The second gas supply unit 17 includes a second gas supply pipe 17 a that supplies the second shield gas along one electrode 11.

  The second gas supply pipe 17 a has one rod-shaped electrode 11 disposed therein, and supplies the second shield gas to the opening 14 a along the outer periphery of the one electrode 11.

  In addition, a channel through which the second shield gas flows is formed at the center of one electrode 11. The second gas supply unit 17 supplies the second shield gas through the one electrode 11.

  Next, the relationship between the first shield gas and the second shield gas for reducing the width and increasing the degree of ionization will be described below.

  As a first idea, the ionization voltage of the second shield gas is preferably lower than the ionization voltage of the first shield gas. By supplying the second shield gas that is easily ionized from the second gas supply pipe 17 a, the ionized state of the second shield gas can be quickly formed in the arc region 13. On the other hand, by supplying the first shield gas that is not easily ionized from the first gas supply pipe 15a, the arc region 13 is compressed from the surroundings by the pressure of the flow of the first shield gas. However, since the ionization voltage of the first shield gas is high, the first shield gas is difficult to be ionized, so that the width of the arc region 13 is suppressed from expanding.

  In FIG. 9, the arc region formed by the welding device of the first embodiment is indicated by a chain line, and the arc region formed by the welding device of the second embodiment is indicated by a solid line.

  FIG. 10 is a diagram showing the ionization voltage and density of the shielding gas that can be used by the welding apparatus 10. The density shown in FIG. 10 is that at a temperature of 300 (normal temperature) K.

  When the first concept described above is applied, for example, Ar having a low ionization voltage can be used as the second shield gas, and He having a high ionization voltage can be used as the first shield gas.

  Next, as a second idea, the density of the first shield gas is preferably higher than the density of the second shield gas. By supplying the first shield gas having a high density from the first gas supply pipe 15a, the base material side portion of the arc region 13 can be sufficiently compressed from the surroundings by the pressure of the flow of the first shield gas. . On the other hand, by supplying the second shield gas having a low density from the center of the second gas supply pipe 17a, the shield gas can be supplied without expanding the width of the arc region 13. In the case of the second idea, it is preferable to supply the second shield gas only from the center of the second gas supply pipe 17a. The gas used may be CO2 gas, N2, Ar, mixed gas Ar + H2, Ar + He, or the like.

  According to the welding apparatus 10 of the present embodiment described above, it is possible to further increase the degree of ionization by narrowing the width of the arc region.

  FIG. 11 is a diagram illustrating a third embodiment of the welding apparatus disclosed in this specification.

  The welding apparatus 10 of the present embodiment further increases the energy density of the melted part.

The energy density given to the melting part is obtained by the following equation.
Energy density = heat input amount (current × voltage) / heat input area Here, the current is a current flowing between one electrode 11 and the other electrode 12, and the voltage is one electrode 11 and the other electrode 12. The voltage applied between the two. The heat input area is the area of the portion of the base material 20 where the arc region is formed.

  In each embodiment mentioned above, the energy density given to a fusion zone was raised by reducing this heat input area.

  In the present embodiment, along with the reduction of the heat input area, the voltage is increased to increase the amount of heat input, thereby further increasing the energy density of the molten part.

  As shown in FIG. 11, the welding apparatus 10 includes a drive unit 21 that drives one electrode 11 so as to change the distance between the one electrode 11 and the base material 20, and drive control that controls the drive unit 21. Unit 22. The drive unit 21 drives one electrode 11 up and down to change the distance between the one electrode 11 and the base material 20. The drive control unit 22 measures a voltage applied between the one electrode 11 and the other electrode 12 and controls the drive unit 21 based on the measured voltage.

  When the distance between one electrode 11 and the base material 20 changes, the arc length of the arc region 13 changes. When the arc length changes, the resistance of the arc region 13 changes. Specifically, the resistance of the arc region 13 increases as the arc length increases and decreases as the arc length decreases.

  On the other hand, in order to perform stable arc welding, it is preferable that the current flowing between one electrode 11 and the other electrode 12 is constant.

  The welding power source 16 changes the voltage applied between the one electrode 11 and the other electrode 12 when the arc length changes and the resistance of the arc region 13 changes, so that the one electrode 11 and the other electrode 12 change. A constant current is supplied between the electrodes 12.

  The welding apparatus 10 first forms the arc region 13 and then enlarges the arc length so that the current flowing between the one electrode 11 and the other electrode 12 is constant, The voltage applied between the electrodes 12 is increased. Then, the arc length is increased until the voltage between one electrode 11 and the other electrode 12 becomes larger than a predetermined threshold. And after reaching the voltage which becomes the amount of heat input which can obtain a predetermined energy density, welding of the base material 20 is further continued while rotating the base material 20. Next, operation | movement of the welding apparatus 10 is demonstrated below with reference to FIG.

  FIG. 12 is a diagram illustrating the relationship between the displacement amount of one electrode, the voltage, and the current. FIG. 13 is a diagram showing arc regions at times t1 and t3 in FIG.

  FIG. 12 shows the amount of upward displacement of one electrode 11, the voltage applied between one electrode 11 and the other electrode 12, and the current flowing between one electrode 11 and the other electrode 12. And the relationship with time.

First, at time t1, the first shield gas is flowed to form the arc region 13. The displacement amount of one electrode 11 at time t1 is zero. When the arc region 13 is formed, the voltage applied between one electrode 11 and the other electrode 12 decreases from V ₀ to V _i and the current increases from zero to I. The distance between the one electrode 11 and the base material 20 when the arc region 13 is first formed may be a distance at which the arc region 13 can be formed by applying the voltage V ₀ . However, if the distance between one electrode 11 and the base material 20 is too large, the arc region 13 cannot be formed. And from time t1 to time t2, the amount of displacement is made constant and the arc region 13 is stabilized.

  Next, at time t <b> 2, the drive control unit 22 controls the drive unit 21 so as to increase the distance between the one electrode 11 and the base material 20. One electrode 11 moves upward on the side opposite to the base material 20 and the amount of displacement begins to increase. The welding power source 16 starts increasing the voltage applied between the one electrode 11 and the other electrode 12 so that the current flowing between the one electrode 11 and the base material 20 becomes constant. As shown in FIG. 12, the voltage increases, but the current changes at a constant value I.

Next, at time t3, when the voltage between the one electrode 11 and the other electrode 12 exceeds a predetermined threshold value _Vf , the drive control unit 22 stops the drive of the one electrode 11. 21 is controlled. At this time, the displacement amount of one of the electrodes 11 is D, and the arc length of the arc region 13 is longer than the initial length by the displacement amount D.

In this way, when the voltage between the one electrode 11 and the other electrode 12 reaches the predetermined threshold value _Vf , a desired heat input amount is obtained. And the welding apparatus 10 rotates the base material 20 in the state which applied the voltage between the one electrode 11 and the other electrode 12, and continues arc welding _Vf .

  In addition, although the preform | base_material 20 has stopped between the time t1 and the time t3 after forming the arc area | region 13 in the welding apparatus 10, arc welding of the preform | base_material 20 is performed.

  Next, referring to FIG. 13, a description will be given below of the welding apparatus 10 preventing an increase in the heat input area and preventing a reduction in energy density when the arc length is increased.

  First, at time t1, the arc region 13 is formed with the displacement amount of one electrode being zero.

  As in the first embodiment described above, the welding apparatus 10 according to the present embodiment is the first to the center of the arc region 13 from the periphery of the portion on the base material side of the arc region 13 from the time t1 to the time t2. 1 Shield gas is flowing.

  If the first shield gas is not flowed, the heat input area increases as the arc length increases. In FIG. 13, at time t3, the shape of the arc region when the first shield gas is not flowing is indicated by a chain line.

  In the welding apparatus 10, since the first shield gas flows from the periphery of the portion on the base material side of the arc region 13 toward the center of the arc region 13, the width of the arc region 13 is prevented from being expanded. An increase in the thermal area is prevented. Therefore, the increase in energy density is prevented from being impaired by the increase in heat input area.

  From this point of view, it is preferable to prevent the width of the arc region 13 from increasing by increasing the ratio of the pressure at the center of the arc region 13 to the pressure outside the arc region as the arc length increases. . Specifically, it is preferable to increase the flow rate of the first shield gas as the arc length increases.

  According to the welding apparatus 10 of the present embodiment described above, the energy density of the fusion zone can be further increased by increasing the voltage and increasing the amount of heat input as well as reducing the heat input area.

  In this invention, the welding method of embodiment mentioned above and the welding apparatus using such a welding method can be suitably changed, unless it deviates from the meaning of this invention. In addition, the configuration requirements of one embodiment can be applied to other embodiments as appropriate.

  For example, as shown in FIG. 14, the welding apparatus 10 disclosed in the present specification includes one electrode 11, the other electrode 12, and the base material 20 connected to the one electrode 11 and the other electrode 12. The first shield gas is flowed from the periphery of the portion on the base metal side of the arc region 13 formed between the arc region 13 and the center of the arc region 13, and the ratio between the pressure at the center of the arc region 13 and the pressure outside the arc region is determined. It is only necessary to include the first gas supply unit that is set to 70 or more and 5000 or less, and other components may be different from the above-described embodiment.

  Moreover, the welding apparatus 10 disclosed in this specification may include a housing 28 having a shape as illustrated in FIGS. 15 to 17.

  FIG. 15 is a diagram illustrating still another example of the welding apparatus disclosed in this specification. 16 is a cross-sectional view taken along line YY of FIG. 17 is a cross-sectional view taken along the line ZZ in FIG.

  The housing 28 includes an upper housing 28a in which one electrode 11 and the nozzle plate 14 are disposed, and a lower housing 28b. In the space formed by the upper casing 28a and the lower casing 28b, the base material 40 is rotatably arranged.

  The base material does not necessarily have a simple cylindrical shape as shown in FIG. In the example shown in FIG. 15, the base material 40 has a convex portion 40 a that protrudes from a cylindrical portion.

  The upper housing 28 a has a recessed portion 32 having a shape corresponding to the protruding portion 40 a of the base material 40. The convex portion 40 a of the base material 40 rotates within the concave portion 32.

  One electrode 11 is fixed to the upper housing 28 a via an electrical insulating material 29.

  A nozzle plate 14 having a nozzle opening 14 a is disposed between one electrode 11 and the base material 40. One electrode 11 is located above the center of the nozzle opening 14a. The nozzle plate 14 may be formed as a part of the housing 18.

  A first gas supply pipe 15a is provided in the lower housing 29b. The first shield gas supplied from the first gas supply pipe 15 a into the housing 28 passes between the housing 28 and the base material 40 and is supplied to the base material side of the nozzle plate 14. Further, the first shield gas flows from the base material side of the nozzle plate 14 to the space on the one electrode 11 side through the nozzle opening 14a. Then, the first shield gas is discharged from the space on the one electrode 11 side through the discharge port 30 to the outside.

  Here, the base material 40 is connected to an external base material rotating device (not shown) using the base material fixing jig 31. The base material rotating device rotates the base material 40 by rotating the base material fixing jig 31.

  The base material fixing jig 31 to which the base material 40 is fixed is inserted into the opening 33 of the housing 28. A gap 34 exists between the base material fixing jig 31 and the housing 28. The gap 34 is provided to prevent the rotating base material fixing jig 31 from coming into contact with the housing 28.

  In a portion other than the opening 33 in the housing 28, the upper housing 28a and the lower housing 28b abut each other with the tapered abutting surfaces to form a closed space.

  The first shield gas supplied from the first gas supply pipe 15a into the housing 28 flows through the gap 34 to the outside.

  On the other hand, a third gas supply pipe 26 that supplies a third gas is disposed inside the base material fixing jig 31, and the third gas is supplied from the third gas supply pipe 26 toward the gap 34. The The third gas supplied to the gap 34 flows from the outside to the inside of the housing 28.

  Accordingly, in the gap 34, the first shield gas flowing from the inside to the outside of the housing 28 and the third gas flowing from the outside to the inside of the housing 28 collide with each other, so that the first shield gas is It is prevented that the body 28 flows from the inside to the outside.

  It is preferable to use the same gas as the first shield gas as the third gas. The flow rate of the third gas is preferably the same as the flow rate of the first shield gas that flows from the inside to the outside of the housing 28 through the gap 34.

  In FIGS. 15 to 17, some components such as an arc region and a sensor are not illustrated.

  As described above, the housing 28 has the opening 33 into which the base material 40 is rotatably inserted. In the opening 33, the housing 28 and the base material 40 or the base material fixing jig 31 are connected. A gap 34 is provided between the first shield gas and the third gas from the outside of the casing 28 to the inside. It is preferable that

  In the welding apparatus 10 shown in FIGS. 15 to 17 described above, it is possible to reliably prevent the first shield gas from flowing outside the housing 28 by flowing the third gas through the sliding portion.

  Next, the welding apparatus disclosed in this specification will be described below using examples. However, the scope of the present invention is not limited to the examples.

[Example]
Arc welding was carried out using the welding apparatus shown in FIGS. In arc welding, the welding current is 50 A, the flow rate of the shielding gas is 25 liters / minute, the distance between one electrode and the base material is 1 mm, and the diameter of the opening is 3 mm. In addition, the forming material of one of the electrodes was tungsten containing cerium, and the forming material of the base material was stainless steel.

  The pressure ratio of the example was 100.

  Arc welding was performed using the conventional welding apparatus shown in FIG. In arc welding, the welding current is 50 A, the flow rate of the shielding gas is 25 liters / minute, the distance between the electrode and the base material is 1 mm, and the forming material of one electrode is cerium-containing. It was tungsten, and the material for forming the base material was stainless steel.

  The pressure ratio of the comparative example was 1.

  The result of having measured the dimension and aspect-ratio of the weld part about each of an Example and a comparative example is shown in FIG.

  The width of the welded part of the example was 32% smaller than that of the comparative example, and the penetration depth was 58% larger. Moreover, the aspect ratio of the welded part of the example was 2.3 times that of the comparative example.

Moreover, the energy density of the Example was 1000 W / mm < ² >, and the energy density of the comparative example was 100 W / mm < ² >.

DESCRIPTION OF SYMBOLS 10 Welding apparatus 11 One electrode 12 The other electrode 13 Arc area | region 14 Nozzle plate 14a Opening part 15 1st gas supply part 15a 1st gas supply pipe 15b 1st pressure sensor 15c 2nd pressure sensor 15d Control part 16 Welding power supply 17 1st 2 Gas supply part 17a Second gas supply pipe 18 Case 19 Electrical insulating material 20 Base material 21 Drive part 22 Drive control part 25 First gas supply pipe 26 Third gas supply pipe 28 Case 28a Upper case 28b Lower case Body 29 Electrical insulating material 30 Discharge port 31 Base material fixing jig 32 Concave portion 33 Opening portion 34 Space 40 Base material 40a Convex portion 100 Welding device 101 Electrode 102 Gas nozzle 103 Arc region 120 Base material W Welding width L Ionization region width

Claims (10)

  The center of the arc region (13) from the periphery of the portion on the base material side of the arc region (13) formed between the one electrode (11) and the base material (20) connected to the other electrode (12). A welding method in which arc welding is performed by flowing a first shield gas toward the part and setting the ratio of the pressure at the center of the arc region (13) to the pressure outside the arc region to 70 to 5000.   Nozzle plate 14 having an opening (14a) through which an arc region (13) formed between the one electrode (11) and a base material (20) connected to the other electrode (12) passes. The first shield gas flows from the base material side of the nozzle plate through the opening (14a) to the one electrode (11) side, and the arc region (13) on the base material side of the nozzle plate (14). 2. The welding method according to claim 1, wherein arc welding is performed by setting a ratio of a pressure at a central portion of the metal and a pressure outside the arc region to 70 to 5,000.   The welding method according to claim 2, wherein a ratio of a cross-sectional area of a portion of the arc region (13) passing through the opening (14a) to an area of the opening (14a) is 1 or more and 35 or less.   The welding method according to claim 2 or 3, wherein a flow rate of the first shield gas passing through the opening (14a) is not less than 5 liters / minute and not more than 35 liters / minute. The opening (14a) has a circular shape,
The ratio between the diameter of the opening (14a) and the distance between the nozzle plate (14) and the base material (20) is 1 or more and 20 or less, according to any one of claims 2 to 4. Welding method.   The welding method according to any one of claims 1 to 5, wherein a second shield gas is allowed to flow from the one electrode (11) side toward the opening (14a).   The welding method according to claim 6, wherein an ionization voltage of the second shield gas is lower than an ionization voltage of the first shield gas.   The welding method according to claim 6, wherein the density of the first shield gas is higher than the density of the second shield gas.   While increasing the distance between the one electrode (11) and the base material (20), the current flowing between the one electrode (11) and the other electrode (12) is constant. The welding method according to any one of claims 1 to 8, wherein a voltage applied between the one electrode (11) and the other electrode (12) is increased.   When the voltage between the one electrode (11) and the other electrode (12) becomes larger than a predetermined threshold, the distance between the one electrode (11) and the base material (20) is increased. The welding method according to claim 9, wherein the welding is stopped.

Images