TIG welding torch with constricted nozzle

Abstract

To provide a TIG welding torch comprising a narrowed nozzle, which can improve safety and a welding quality.SOLUTION: A TIG welding torch comprising a narrowed nozzle is provided with a conductive electrode nozzle 1, provided at a tip part of a torch body 7, which stores a narrowed nozzle 2, and an earth cable connection terminal 3 electrically connected to the electrode nozzle 1. The electrode nozzle 1 comprises a cylindrical nozzle body 1A and a beam nozzle 1B detachably attached to the nozzle body 1A. The beam nozzle 1B comprises a conical tapered part 1d having a nozzle hole 1c at a tip thereof, and a cylindrical part 1f connected to a rear end of the tapered part 1d and having a screw part that is screwed to the nozzle body 1A. The tapered part 1d has a tip edge 1g whose base material can be contacted with the whole circumference of the nozzle hole 1c and also has a first gas exhaust hole 1h on a conical peripheral side surface thereof. The nozzle body 1A has a second gas exhaust hole 1b on a cylindrical peripheral side surface thereof.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a TIG welding torch having a constricted nozzle, and particularly to a TIG welding torch suitable for spot welding.

Background Art

[0002] Conventionally, in TIG welding, generally, an arc is generated between a base material connected to one electrode of a welding power source and a tungsten electrode rod connected to the other electrode, and an inert gas is used as a shielding gas between the electrode rod and the base material. By flowing the shielding gas and covering the electrode rod, the arc, and the molten pool with the shielding gas, the molten metal is protected from being adversely affected by the intrusion of oxygen, nitrogen, etc. in the atmosphere, and the electrode rod is prevented from being oxidized and consumed.

[0003] Conventional TIG welding requires time to connect the base material to one electrode of the welding power source, and it requires skill because it is necessary to hold the torch so that the distance between the electrode rod and the base material is constant in order to perform good welding.

[0004] Therefore, the inventor has proposed a TIG welding torch with a constricted nozzle that does not require connection between the base material and the welding power source and can perform good welding even by non-experts (Patent Documents 1 to 3).

[0005] These TIG welding torches with constricted nozzles each include a metal electrode nozzle 1 and a constricted nozzle 2 housed in the electrode nozzle 1, as shown in FIGS. 1 to 3. An earth cable connection terminal 3 electrically connected to the electrode nozzle 1 is connected to one electrode terminal of a welding power source (not shown) via an earth cable 4, and an electrode rod 5 is connected to the other electrode terminal of the welding power source via an electric cable.

[0006] As shown in FIG. 4, for example, the constricted nozzle 2 has support protrusions 2a protruding from the inner peripheral surface that concentrically support the electrode rod 5 inserted through the constricted nozzle 2, and gaps 2b between adjacent support protrusions 2a are configured as passages for the shielding gas G (Patent Documents 1 to 5, Non-Patent Document 1, etc.).

[0007] In the TIG welding torches with narrow nozzles described in Patent Documents 1 to 3, the electrode nozzle 1 is connected to the electrode terminal (usually the cathode terminal) of the welding power supply. Therefore, when the electrode nozzle 1 is brought into contact with the base material W during welding, the base material W is grounded to the welding power supply via the electrode nozzle 1. As a result, there is no need to ground the base material W as in conventional methods. Furthermore, since the electrode rod 5 is fixed at a predetermined distance inward from the tip of the electrode nozzle 1 by a collet 6 inside the torch body, the operator holding the torch does not need to adjust the distance between the base material W and the electrode rod 5 during manual welding, and stable and good welding can be performed even by those who are not skilled in TIG welding. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. WO2020 / 137949 [Patent Document 2] Japanese Patent Publication No. 2022-308 [Patent Document 3] Japanese Patent Publication No. 2022-70060 [Patent Document 4] Japanese Patent Publication No. 2012-139704 [Patent Document 5] International Publication No. WO2013 / 157036 [Non-patent literature]

[0009] [Non-Patent Document 1] Kyohei Konishi, Masaya Shigemoto, Manabu Tanaka, Akihisa Murata, Yusuke Murata, Anthony B. Murphy, Japan Society for Light Metal Welding, Vol. 55, No. 6, 2017, pp. 227-232. [Overview of the project] [Problems that the invention aims to solve]

[0010] In the TIG welding torch with a constricted nozzle shown in Figure 1, a gas venting groove 1a is formed on the tip surface of the electrode nozzle 1, and a gas discharge hole 1b is formed at the bottom of the internal space of the electrode nozzle 1 (upper part of the figure), so that the shielding gas G supplied into the electrode nozzle 1 is discharged from both the tip end and the end away from the tip.

[0011] During welding, the tip of the electrode nozzle 1 is brought into contact with the base material W. The gas vent groove 1a quickly discharges metal vapor to the outside when the arc is generated, thereby suppressing wear on the electrode rod 5 due to metal vapor. Furthermore, by providing a gas discharge hole 1b at the end of the electrode nozzle 1 away from the tip, the shielding gas G that could not escape from the gas vent groove 1a flows around the arc and the molten metal before being discharged from the gas discharge hole 1b. This ensures that the molten metal and the arc are reliably and effectively protected from the air.

[0012] However, the metal vapor discharged from the vent groove 1a is deposited onto the base material W, leaving radial metal vapor trails on the surface of the base material W around the welding spot. While these metal vapor trails do not negatively affect the welding quality, they do impair the appearance. Furthermore, the arc during firing leaks out of the vent groove 1a, and viewing it with the naked eye could damage the eyes, requiring the use of safety glasses.

[0013] As shown in Figure 2, the above-mentioned appearance problem can be resolved by not forming a gas vent groove on the tip surface of the electrode nozzle 1.

[0014] However, as shown in Figure 2, in a configuration where a gas vent groove is not formed on the tip surface of the electrode nozzle 1, and a gas discharge hole 1b is formed only at the bottom of the internal space of the electrode nozzle 1, away from the tip of the electrode nozzle 1, metal vapor is not discharged immediately, which may accelerate the wear of the electrode rod 5 due to metal vapor. Also, if a gas vent groove is not provided on the tip surface of the electrode nozzle 1, the gas pressure of the shielding gas G injected during spot welding will cause a lateral force to be applied to the tip of the electrode nozzle 1 from the inside of the electrode nozzle 1, which may cause the torch to shift laterally (in the direction of arrow X) during welding. Furthermore, if a gas vent groove 1a is not provided on the tip surface of the electrode nozzle 1, soot from metal vapor will accumulate inside the electrode nozzle 1.

[0015] Therefore, the main objective of the present invention is to provide a TIG welding torch equipped with a constricted nozzle that improves upon the conventional TIG welding torch equipped with a constricted nozzle and can solve the various problems described above. [Means for solving the problem]

[0016] To achieve the above object, a TIG welding torch including a constriction nozzle according to an embodiment of the present invention includes a torch body, a collet that is detachably inserted into the torch body, holds an electrode rod, and allows a shielding gas to pass along the electrode rod, a constriction nozzle provided on the tip side of the collet, concentrically supporting the electrode rod, and injecting the shielding gas toward the tip of the electrode rod through a gap between the constriction nozzle and the electrode rod, a conductive electrode nozzle provided at the tip of the torch body and accommodating the constriction nozzle, and an earth cable connection terminal electrically connected to the electrode nozzle. The electrode nozzle includes a cylindrical nozzle body and a beam nozzle detachably attached to the nozzle body. The beam nozzle includes a conical tapered portion having a nozzle hole at the tip and a cylindrical portion provided at the rear end of the tapered portion and having a screw portion for screwing onto the nozzle body. The tapered portion has a tip edge where the entire circumference of the nozzle hole can contact the base material and a first gas discharge hole on the conical circumferential side surface. The nozzle body has a second gas discharge hole on the cylindrical circumferential side surface.

[0017] The tip of the constriction nozzle is disposed at a position separated inward by a predetermined distance from the tip position of the electrode nozzle, and the first gas discharge hole can be provided on the side of the tip position of the constriction nozzle.

[0018] The first gas discharge hole can be formed such that the gas discharge direction does not face a virtual plane that is orthogonal to the axis of the constriction nozzle and contacts the tip edge of the electrode nozzle.

[0019] The first gas discharge hole can be directed in a direction orthogonal to the axis of the constriction nozzle.

[0020] The tip position of the constriction nozzle can be located 3 to 4 mm inside the tip position of the electrode nozzle. The constriction nozzle can be connected to the tip side of the collet via an extension adapter.

Advantages of the Invention

[0021] According to the TIG welding torch equipped with a constriction nozzle according to the present invention, when the arc is initiated, the space between the electrode nozzle and the base material is blocked, so that the shielding gas ejected from the constriction nozzle is discharged from the first gas discharge hole 1h and the second gas discharge hole 1b. Since the space between the electrode nozzle and the base material is blocked, the metal vapor during welding does not leak from between the electrode nozzle and the base material, so that no deposition trace of the metal vapor remains around the welding spot.

[0022] In addition, since the shielding gas can be discharged from the first gas discharge hole provided between the second gas discharge hole and the tip of the electrode nozzle, even if the space between the electrode nozzle and the base material is blocked, the torch that was held by the gas pressure of the shielding gas from the inside at the tip of the electrode nozzle can be prevented from being pushed sideways and displaced.

[0023] Moreover, the metal vapor generated when the arc is initiated is discharged together with the shielding gas from the first gas discharge hole and the second gas discharge hole, so that the metal vapor can be prevented from staying in the electrode nozzle and soot due to the metal vapor from depositing on the inner surface of the electrode nozzle.

[0024] In addition, since the leakage of the arc from between the electrode nozzle and the base material can be prevented, the eyes of the operator will not be injured even without wearing protective goggles. In particular, since the arc is generated between the portion of the electrode rod protruding from the tip of the constriction nozzle and the base material, the leakage of the arc can be effectively prevented by arranging the first gas discharge hole on the side of the tip position of the constriction nozzle.

Brief Description of the Drawings

[0025] [Figure 1] It is a longitudinal front view showing an example of a conventional TIG welding torch equipped with a constriction nozzle. [Figure 2] It is a longitudinal front view showing another example of a conventional TIG welding torch equipped with a constriction nozzle. [Figure 3] It is a longitudinal front view showing still another example of a conventional TIG welding torch equipped with a constriction nozzle. [Figure 4]Figure 2 shows the constricted nozzle, a component of the torch, Figure 4(A) is a front view, Figure 4(B) is a longitudinal front view, and Figure 4(C) is a cross-sectional view of Figure 4(B). [Figure 5] This is a longitudinal cross-sectional front view showing a first embodiment of a TIG welding torch equipped with a constricted nozzle according to the present invention. [Figure 6] Figure 5 is a perspective view of the first embodiment. [Figure 7] This is an enlarged view of section VII in Figure 5. [Figure 8] This is a longitudinal cross-sectional front view showing a second embodiment of a TIG welding torch equipped with a constricted nozzle according to the present invention. [Figure 9] Figure 8 is a perspective view of the second embodiment. [Modes for carrying out the invention]

[0026] A first embodiment of a TIG welding torch equipped with a constricted nozzle according to the present invention will be described below with reference to Figures 5 to 7. Note that the same reference numerals are used throughout all figures, including those of the prior art, to indicate the same components.

[0027] A TIG welding torch according to the first embodiment of the present invention, with reference to Figures 5 to 7, includes a torch body 7, a collet 6 detachably inserted into the torch body 7 to hold an electrode rod 5 and pass shielding gas G along the electrode rod 5, a constriction nozzle 2 provided on the tip side of the collet 6 to concentrically support the electrode rod 5 and to inject shielding gas G towards the tip of the electrode rod 5 by passing shielding gas G through the gap 2b between the collet 6 and the electrode rod 5, a conductive electrode nozzle 1 provided at the tip of the torch body 7 to house the constriction nozzle 2, and an earth cable connection terminal 3 electrically connected to the electrode nozzle 1.

[0028] In the illustrated example, the torch body 7 is cylindrical and consists of an upper part 7a and a lower part 7b that are connected to each other. The torch body 7 is made of a non-conductive insulating material (e.g., a resin material).

[0029] The collet 6 has a one-touch tube joint 8 and a torch cable connection terminal 9 attached to its rear end. A gas tube (not shown) is connected to the tube joint 8 to supply shielding gas G. The torch cable connection terminal 9 is connected to the electrode terminal (e.g., positive electrode) of a welding power source (not shown) by an electrical cable (not shown). A gripping cylinder 10 for the operator to hold is fixed to the upper part 7a of the torch body 7. In the illustrated example, the gripping cylinder 10 is made of transparent polycarbonate.

[0030] The constricting nozzle 2 is connected to the tip of the collet 6 via a nozzle mounting bracket 11. The nozzle mounting bracket 11 has its rear end screwed to the tip of the collet 6 and its front end screwed to the constricting nozzle 2. The nozzle mounting bracket 11 is fixed inside the lower part 7b of the torch body 7. By screwing the collet 6 into the nozzle mounting bracket 11, the collet 6 is tightened and grips the tungsten electrode rod 5.

[0031] The constricted nozzle 2 is similar to the conventional known examples described in Japanese Patent Publication No. 2022-308 and Japanese Patent Publication No. 2022-70060, and as shown in Figure 4, the support projections 2a protruding from the inner circumferential surface hold the electrode rod 5 concentrically, and the gap 2b between the support projections 2a is configured as a passage for the shielding gas G.

[0032] A cylindrical grounding connector 12 is fixed to the outer circumference of the lower part 7b of the torch body 7, and the electrode nozzle 1 is attached to the grounding connector 12 by screw connection. The grounding connector 12 is made of a metal material (conductive material). The grounding connector 12 is fitted onto the lower part 7b and is fixed to the lower part 7b by embedded screws or the like. A grounding cable connection terminal 3 is attached to the grounding connector 12. The grounding cable connection terminal 3 is connected to the electrode terminal (e.g., cathode terminal) of a welding power supply (not shown) via a grounding cable 4.

[0033] The electrode nozzle 1 comprises a cylindrical nozzle body 1A and a beam nozzle 1B detachably attached to the nozzle body 1A. The nozzle body 1A is electrically connected to the grounding fitting 12 by screw connection. The nozzle body 1A and the beam nozzle 1B can be formed from the same metal material or from different metal materials.

[0034] The beam nozzle 1B comprises a conical tapered portion 1d having a nozzle hole 1c at its tip, and a cylindrical portion 1f connected to the rear end of the tapered portion 1d and having a threaded portion 1e for detachably screwing onto the nozzle body 1A.

[0035] Since it may be necessary to change the diameter of the nozzle hole 1c of the beam nozzle 1B depending on the magnitude of the welding current used for arc discharge, in such cases, the beam nozzle 1B can be replaced with one having a nozzle hole 1c with a diameter corresponding to the magnitude of the welding current.

[0036] The tapered portion 1d has a tip edge 1g that can contact the base material W around the entire circumference of the nozzle hole 1c. By bringing the tip edge 1g into contact with the base material W, shielding gas G can be prevented from leaking between the tip of the electrode nozzle 1 and the base material W. The tip edge 1g can be a flat surface. A first gas discharge hole 1h is provided on the conical circumferential surface of the tapered portion 1d.

[0037] The first gas discharge hole 1h is preferably located to the side of the tip of the constricted nozzle 2. Here, "to the side of the tip of the constricted nozzle 2" means in the radial direction centered on the axis of the constricted nozzle 2. The axis of the constricted nozzle 2 substantially coincides with the axis of the electrode rod 5. The first gas discharge hole 1h can be located at the tip of the constricted nozzle 2, where a straight line perpendicular to the axis of the constricted nozzle 2 passes through. The diameter of the first gas discharge hole 1h can be, for example, 1.3 to 2.0 mm.

[0038] A second gas discharge hole 1b is provided on the cylindrical circumferential surface of the nozzle body 1A. In the illustrated example, there are four second gas discharge holes 1b, but the number can be set as appropriate.

[0039] The tip of the constriction nozzle 2 is positioned at a predetermined distance H1 (3-4 mm) from the tip of the electrode nozzle 1. By bringing the tip of the constriction nozzle 2 closer to the tip of the electrode nozzle 1 to a predetermined distance H1, the effect of expelling metal vapor by the shielding gas G through the first gas discharge hole 1h is enhanced. The tip of the electrode rod 5 protrudes from the tip of the constriction nozzle 2 and is held by the collet 6 so as to be fixed at a distance H2 (for example, 0.3-1.0 mm) inward from the tip of the electrode nozzle 1. The tip of the electrode nozzle 1 corresponds to the surface position of the base material W to which the tip edge 1g of the electrode nozzle 1 abuts.

[0040] The first gas discharge hole 1h is formed such that the gas discharge direction is perpendicular to the axis of the constricted nozzle 2 (corresponding to the axis of the electrode rod 5) and does not face a virtual plane that is in contact with the tip edge of the electrode nozzle 1. This virtual plane corresponds to the surface of the base material W that the electrode nozzle 1 contacts during welding.

[0041] The second gas discharge port 1b is located at the very bottom of the internal space of the electrode nozzle 1, at a distance H3 (for example, 15-20 mm) sufficiently far rearward from the tip position of the constricted nozzle 2.

[0042] The diameter and number of the first gas outlet 1h and the second gas outlet 1b can be appropriately set according to the welding target. In the illustrated example, there are four first gas outlets 1h and four second gas outlets 1b, all of which have the same diameter.

[0043] In a TIG welding torch equipped with a constricted nozzle having the above configuration, the tip edge 1g of the beam nozzle 1B is brought into contact with the base material W during spot welding, thereby blocking the space between the electrode nozzle 1 and the base material W. By bringing the electrode nozzle 1 into contact with the base material W, the electrode nozzle 1 and the base material W are electrically connected, and the base material W is connected to a welding power source (not shown). In this state, shielding gas G is injected from the constricted nozzle 2. After a certain period of time (e.g., 0.2 seconds) has elapsed since the start of injection of shielding gas G, an arc is lit between the electrode rod 5 and the base material W for a certain period of time (e.g., 0.2 seconds). After stopping the arc, the injection of shielding gas is stopped after a certain period of time (e.g., 0.1 seconds) has elapsed, and the spot welding is completed.

[0044] As described above, when the arc is ignited, the space between the electrode nozzle 1 and the base material W is sealed, causing the shielding gas G injected from the constricted nozzle 2 to be discharged through the first gas discharge hole 1h and the second gas discharge hole 1b. Because the space between the electrode nozzle 1 and the base material W is sealed, metal vapor does not leak from between the electrode nozzle 1 and the base material W during welding, and therefore no metal vapor deposition marks are left around the welding spot.

[0045] Furthermore, since the shielding gas G can be discharged from the first gas discharge hole 1h located between the second gas discharge hole 1b and the tip of the electrode nozzle 1, even if the space between the electrode nozzle 1 and the base material W is blocked, the gas pressure of the shielding gas G from inside the electrode nozzle 1 will prevent the torch being pushed laterally and displaced at the tip of the electrode nozzle 1.

[0046] Furthermore, the metal vapor generated during arc ignition is discharged together with the shielding gas G from the first gas discharge port 1h and the second gas discharge port 1b, thereby suppressing the accumulation of metal vapor within the electrode nozzle 1 and preventing soot from accumulating on the inner surface of the electrode nozzle 1.

[0047] Furthermore, since arc leakage from between the electrode nozzle 1 and the base material W can be prevented, the worker's eyes will not be harmed even without wearing safety glasses. In particular, since the arc is generated between the portion of the electrode rod 5 protruding from the tip of the constricted nozzle 2 and the base material W, by positioning the first gas discharge hole 1h to the side of the tip of the constricted nozzle 2, arc leakage can be effectively prevented.

[0048] A comparative test was conducted to investigate the state of the electrode rod and the state of the molten pool after four firings under the following conditions, comparing the embodiment according to the first embodiment described above with a conventional comparative example (the form shown in Figure 2) that does not have a gas discharge groove at the tip of the electrode nozzle.

[0049] For both the examples and comparative examples, the test conditions were as follows: arc length: 1 mm, electrode rod diameter: 1.6 mm, taper angle of the electrode rod tip: 40°, arc ignition time: 0.2 seconds, base material (thickness): C2600 (0.8 mm), shielding gas type and flow rate: Ar, 1.5 liters / min, welding current: 100 A to 200 A (increasing by 20 A increments), and two types of nozzle bore inner diameters, 2.0 mm and 5.0 mm, were used.

[0050] The results of the comparative tests described above showed that when the inner diameter of the nozzle hole was 5.0 mm, no significant difference in the appearance of the electrode rod was observed between the example and the comparative example. On the other hand, when the inner diameter of the nozzle hole was 2.0 mm, the electrode rod of the example remained clean and maintained its initial state, while the comparative example had a dirty appearance due to the adhesion of metal vapor. Furthermore, when the inner diameter of the nozzle hole was 5 mm, the part of the molten pool directly below the electrode rod (the center of the molten pool) was concave in the comparative example, but raised in the example, indicating that the example reduced the occurrence of holes during welding.

[0051] Figure 8 is a cross-sectional view showing a second embodiment of a TIG welding torch equipped with a constricting nozzle according to the present invention, and Figure 9 is a perspective view showing its external appearance. The second embodiment differs from the first embodiment in that the electrode nozzle 1 is equipped with a water-cooling jacket 1C. The water-cooling jacket 1C is made of metal (conductive) and is connected between the nozzle body 1A and the beam nozzle 1B. The water-cooling jacket 1C has a flow path 1Cc through which cooling water passes between the inner cylinder 1Ca and the outer cylinder 1Cb, and the outer cylinder 1Cb is fitted with a cooling water inlet 1Cd and outlet 1Ce. Furthermore, the constricting nozzle 2 is connected to the nozzle mounting bracket 11 via an extension adapter 2c, so that the distance between the tip position of the constricting nozzle 2 and the tip position of the electrode nozzle 1 can be set to a predetermined distance (3-4 mm). The other configurations are the same as those of the first embodiment, and the water-cooling jacket 1C is described in detail in Japanese Patent Application Publication No. 2022-70060 and is publicly known, so a detailed explanation is omitted.

[0052] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0053] 1 Electrode nozzle 1A Nozzle Body 1B Beam Nozzle 1C Water-Cooled Jacket 1b Second gas outlet 1c Nozzle hole 1d Narrowing part 1e Screw part 1f Cylindrical section 1h First gas outlet 1g tip edge 2. Narrowing nozzle 2C extension adapter 3. Ground cable connection terminal 4. Ground cable 5 Electrode rod 6 Colette 7 Torch Body

Claims

1. Torch body and A collet is detachably inserted into the torch body, holds the electrode rod, and allows a shielding gas to pass along the electrode rod, A constricting nozzle is provided on the tip side of the collet, which concentrically supports the electrode rod and injects the shielding gas towards the tip of the electrode rod through the gap between the nozzle and the electrode rod, A conductive electrode nozzle is provided at the tip of the torch body and houses the constricted nozzle, The electrode nozzle has an earth cable connection terminal that is electrically connected to it, The electrode nozzle comprises a cylindrical nozzle body and a beam nozzle detachably attached to the nozzle body. The beam nozzle comprises a conical tapered portion having a nozzle hole at its tip, and a cylindrical portion connected to the rear end of the tapered portion and having a threaded portion for screwing onto the nozzle body. The tapered portion has a tip edge that can contact the base material around the entire circumference of the nozzle hole, and has a first gas discharge hole on its conical circumferential surface. The nozzle body has a second gas discharge hole on its cylindrical circumferential surface. The tip of the constricted nozzle is positioned at a predetermined distance inward from the tip of the electrode nozzle. The first gas discharge hole is provided to the side of the tip of the constricted nozzle, and the gas discharge direction is formed so as not to be perpendicular to the axis of the constricted nozzle and to be directed toward a virtual plane that is in contact with the tip edge of the electrode nozzle. A TIG welding torch equipped with a constricted nozzle.

2. A TIG welding torch comprising a constricted nozzle according to claim 1, wherein the first gas discharge hole is directed in a direction perpendicular to the axis of the constricted nozzle.

3. A TIG welding torch comprising a constricted nozzle according to claim 1, wherein the tip position of the constricted nozzle is located 3 to 4 mm inward from the tip position of the electrode nozzle.

4. A TIG welding torch comprising the constriction nozzle according to claim 3, wherein the constriction nozzle is connected to the tip side of the collet via an extension adapter.

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