JP7315514B2 - Gas shield jig and gas shield welding equipment - Google Patents

Description

The present invention relates to a gas shield jig and a gas shield welding device.

2. Description of the Related Art Gas-shielded arc welding is known in which a shield gas (inert gas) is supplied to a weld to shield the weld from air and prevent oxidation. A gas shield welding nozzle used for such gas shield arc welding is described in Patent Document 1, for example.
The gas shield welding nozzle of Patent Document 1 includes a shield member that is attached to a nozzle body to surround shield gas and shield air. The shield member includes a shield core material having elasticity capable of being deformed and restored in the radial direction, and a planar insulating heat-resistant sheet that wraps the outer periphery of the shield core material and has electrical insulation.

By the way, in welding using a base material made of an active metal such as titanium and a welding wire, the active metal has a strong affinity with the atmosphere, especially at high temperatures, so it easily reacts with oxygen and nitrogen in the air to form oxides and nitrides. After welding, the areas where oxides and nitrides are formed are hardened and weakened. For this reason, when welding active metals, in order to avoid contact between the atmosphere and the active metals, jigs for after-shielding and back-shielding are generally used to partially shield the gas near the torch.

JP 2018-144066 A

In recent years, there is an increasing need for modeling using 3D printers as a means of production, and research and development are proceeding toward the practical use of modeling using metal materials. 3D printers that model metal materials use heat sources such as lasers, electron beams, and arcs to melt metal powder and metal wires, and create models by layering the molten metal. However, when performing gas-shield welding of active metals such as those described above, there is a risk that a jig or the like may interfere with the laminated structure, which limits the trajectory planning of the torch movement.

Electron beam (EB) welding, powder LMD (Laser Metal Deposition), and welding by TIG/MIG are mentioned as other manufacturing methods of a laminate-molded article. However, in electron beam lamination welding, welding is performed in a vacuum chamber, and in powder LMD and TIG/MIG methods, the entire molded object is enclosed in a simple sealed chamber and laminated in a shield gas atmosphere. Therefore, in any case, there are restrictions on the shape, size, and trajectory planning of the laminate-molded product, and the degree of freedom in design is inevitably lowered.

Therefore, it is an object of the present invention to provide a gas shield jig and a gas shield welding apparatus capable of suppressing a decrease in the degree of freedom in designing a layered product by performing welding while reliably covering the periphery of the torch with a shield gas even during layered manufacturing in which obstacles tend to occur on the torch track.

The present invention consists of the following configurations.
(1) A gas shield jig provided in a gas shield welding torch for welding in a shield gas atmosphere and shielding the surroundings of the welded part from the atmosphere,
a support fixed to the torch;
a skeletal member that is elastically deformably held by the support portion and arranged to surround the torch;
a sheet member provided to cover the frame member and surround the torch;
with
The skeleton member has a shape that widens along the axis of the torch from the torch proximal end side toward the torch distal end side,
The sheet member is a gas shield jig having an opening on the base end side of the torch.
(2) A gas shield welding apparatus in which the gas shield jig of (1) is provided on the torch for gas shield welding for welding in a shield gas atmosphere.

According to the present invention, even during laminate manufacturing in which obstacles are likely to occur in the orbit of the torch, welding can be performed while the surroundings of the torch are reliably covered with shield gas, and a decrease in the degree of freedom in designing the laminate-molded article can be suppressed.

FIG. 1 is a schematic configuration diagram of a gas shield welding apparatus. FIG. 2 is a front view showing a schematic configuration of the gas shield jig. FIG. 3 is a cross-sectional view schematically showing the configuration of the aftershield portion. FIG. 4 is an explanatory diagram schematically showing the flow of shielding gas by the gas shielding jig during welding. FIG. 5A is an explanatory diagram schematically showing a state in which the gas shield jig is held at the lowered position, and FIG. 5B schematically shows a state in which the gas shield jig is held at the raised position. (A) and (B) of FIG. 6 are explanatory diagrams showing how the skeleton member of the gas shield jig is deformed. FIG. 7 is an explanatory view schematically showing how the gas shield jig moves while bending along the torch track.

Hereinafter, one embodiment of a gas shield welding apparatus provided with a gas shield jig according to the present invention will be described in detail with reference to the drawings. Here, the case of arc gas shield welding will be described as an example, but the present invention is not limited to this, and can also be applied to other welding methods such as laser welding.

<Gas shield welding equipment>
FIG. 1 is a schematic configuration diagram of a gas shield welding apparatus.
The gas shield welding apparatus 100 includes a welding robot 11 , a robot controller 13 , a filler material supply section 15 , a shield gas supply section 17 , a welding power source 19 and a control section 21 .

The welding robot 11 is an articulated robot, and a torch 23 is supported on the tip shaft. The position and posture of the torch 23 can be arbitrarily set three-dimensionally within the range of degrees of freedom of the robot arm. The torch 23 holds the filler material M continuously supplied from the filler material supply unit 15 in a state of protruding from the tip of the torch.

The torch 23 has a shield nozzle (not shown), and a shield gas is supplied to the welding portion from the shield nozzle. The arc welding method may be a consumable electrode method such as coated arc welding or carbon dioxide gas arc welding, or a non-consumable electrode method such as TIG welding or plasma arc welding, and is appropriately selected according to the laminate product to be manufactured.

For example, in the case of the consumable electrode type, a contact tip is arranged inside the shield nozzle, and the contact tip holds the filler material M to which the melting current is supplied. The torch 23 holds the filler material M and generates an arc from the tip of the filler material M in a shield gas atmosphere. The filler material M is fed to the torch 23 by a delivery mechanism (not shown) attached to a robot arm or the like. When the continuously fed filler material M is melted and solidified while moving the torch 23 , a weld bead 29 , which is a melted and solidified body of the filler material M, is formed on the base plate 25 .

The heat source for melting the filler material M is not limited to the arc described above. For example, a heat source using other methods such as a heating method using both an arc and a laser, a heating method using plasma, a heating method using an electron beam or a laser, or the like may be employed. When heating with an electron beam or laser, the amount of heating can be more finely controlled, the state of the welding bead can be maintained more appropriately, and the quality of the laminate-molded product can be further improved.

The filler material M can be any commercially available welding wire. For example, MAG welding and MIG welding solid wires for mild steel, high-strength steel and low-temperature steel (JIS Z 3312), arc welding flux-cored wires for mild steel, high-strength steel and low-temperature steel (JIS Z 3313), etc. Wires specified can be used.

An active metal such as titanium can also be used as the filler material M. In that case, it is necessary to create a shielding gas atmosphere in the weld zone in order to avoid oxidation and nitridation due to reaction with the atmosphere during welding.

The shield gas supply unit supplies inert gas to the weld. In MIG welding, argon, helium (or a mixed gas thereof), or a gas obtained by adding a small amount of active gas such as oxygen or carbon dioxide is used as a shielding gas. On the other hand, in MAG welding, carbon dioxide gas or a mixed gas of argon and carbon dioxide gas is used as the shield gas, and in TIG welding, argon gas is used. Furthermore, in laser welding, nitrogen, argon, helium or the like is used as a shield gas.

A gas shield jig 31 surrounding the torch 23 is attached to the torch 23 , details of which will be described later.

The robot controller 13 receives instructions from the control section 21 to drive each section of the welding robot 11, and controls the output of the welding power source as necessary.

The control unit 21 is composed of a computer device including a CPU, memory, storage, etc., and executes a drive program prepared in advance or a drive program created under desired conditions to drive each part such as the welding robot 11. As a result, the torch 23 is moved according to the driving program, and a plurality of layers of the welding beads 29 are laminated on the base plate 25, thereby forming the laminate-molded article W having a multilayer structure.

<Gas shield jig>
FIG. 2 is a front view showing a schematic configuration of the gas shield jig 31. As shown in FIG.
The gas shield jig 31 includes a support portion 33 fixed to the torch 23, a skeleton member 35 that is elastically deformably held by the support portion 33 and arranged to surround the torch 23, and a sheet member 37 that covers the skeleton member 35 and defines a space around the torch 23. This configuration further includes a gas supply unit 39 that supplies shielding gas to the space around the torch 23 defined by the sheet member 37 .

The support part 33 has a fixing bracket 41 fixed to the torch 23, a support shaft 43 provided integrally with the fixing bracket 41 and extending in the axial direction of the torch 23, and a slider 45 arranged on the opposite side of the support shaft 43 from the torch tip side.

The slider 45 supports the frame member 35 and is fixed to the support shaft 43 so as to be slidable along with the frame member 35 in the axial direction of the support shaft 43 and positionable in the axial direction. The slider 45 functions as a slide mechanism that moves the frame member 35 and the sheet member 37 along the axis of the torch 23 . The slide mechanism may be configured, for example, to slide by screwing a female thread provided on the slider 45 and a male thread provided on the support shaft 43, or may be configured to slide by an actuator such as an air cylinder (not shown).

The skeleton member 35 has at least one support piece 35a supported by the slider 45, a first annular portion 35b, a second annular portion 35c, and a plurality of strut portions 35d. The first annular portion 35b is connected to the support piece 35a and arranged on the torch proximal end side. The second annular portion 35c is separated from the first annular portion 35b and arranged on the tip side of the torch. The strut portion 35d is provided by connecting the first annular portion 35b and the second annular portion 35c. The first annular portion 35b and the second annular portion 35c are substantially circular, and the diameter of the second annular portion 35c is larger than that of the first annular portion 35b. Thereby, the skeleton member 35 has a shape that widens along the axis of the torch 23 from the torch proximal end side to the torch distal end side.

A sheet member 37 is provided to cover the frame member 35 and block the atmosphere so that the surroundings of the torch 23 are filled with the shielding gas. An opening 37a is provided in the upper portion of the sheet member 37 on the torch base end side to open the surrounding space of the torch 23 to the atmosphere. That is, the sheet member 37 has a truncated cone shape (peripheral surface shape of a truncated cone) with the top and bottom surfaces penetrating therethrough, and is provided further extending from the widened distal end edge (second annular portion 35 c ) of the skeleton member 35 . The sheet member 37 is integrated with the skeleton member 35 by bonding or engaging with the skeleton member 35 at least part of the portion that contacts the skeleton member 35 .

Since the sheet member 37 is arranged near the torch 23, it is preferably a fireproof sheet or a flameproof sheet. Moreover, if the sheet member 27 is wholly or at least partly made of a translucent material, the state of the welded portion inside the sheet member 37 can be visually recognized, and the welding state can be easily monitored.

Examples of flame-retardant sheets or non-combustible sheets include sheets with flame-retardant properties specified in JIS A 8952 "Construction work sheets", and A-, B-, and C-type sheets specified in JIS A 1323-1995 "Test method for flame retardancy against welding and fusing sparks of construction work sheets". Moreover, as a sheet having translucency, for example, a transparent noncombustible sheet obtained by coating a base fabric of glass fiber cloth with a photocurable resin can be given as an example.

The gas shield jig 31 of this configuration further includes an after shield portion 47 at the end of the support shaft 43 on the torch tip side, and a gas supply pipe 49 for supplying shield gas to the after shield portion 47 . The after shield part 47 is provided extending rearward in the welding direction TD indicated by an arrow in FIG. That is, the after shield part 47 is arranged so as to cover the area after welding.

FIG. 3 is a cross-sectional view schematically showing the configuration of the after shield portion 47. As shown in FIG.
The aftershield part 47 has a box-shaped housing 51 having an opening 51 a , a wire netting 53 made of copper or stainless steel covering the opening 51 a , and a rectifier 55 arranged inside the housing 51 . A gas supply pipe 49 is connected to the bottom surface 51 b (upper surface in FIG. 3 ) of the housing 51 to supply the shielding gas G into the housing 51 . The rectifying body 55 is arranged with a space 59 provided between it and the connecting portion 57 of the gas supply pipe 49, and is made of a laminated material of steel wool or mesh. The shielding gas G supplied into the housing 51 is discharged through the wire mesh 53 after the flow of the gas is laminarized by the rectifier 55 . The after-shield part 47 described above is an example, and the inside of the housing 51 may be hollow.

As described above, the torch 23 has a shield nozzle (not shown) that supplies shield gas to the welding portion, and has a gas supply line that supplies the shield gas from the shield nozzle to the periphery of the torch inside the sheet member 37 . It is preferable to supply the shielding gas to the after shield portion 47 through the gas supply pipe 49 described above separately from this gas supply line.

In this configuration, the area after welding is covered with the gas shield jig 31 . Therefore, the after shield part 47 and the gas supply pipe 49 can be omitted by adjusting the supply of the shield gas from the torch 23 depending on the welding conditions.

<Action of gas shield jig>
Next, the action of the gas shield jig 31 will be described.
FIG. 4 is an explanatory diagram schematically showing the flow of shielding gas by the gas shielding jig 31 during welding.

When an arc is generated from the torch 23 to form the laminate-molded article W on the base plate 25, shielding gas is supplied from the torch 23 to the welded portion, and the shielding gas G is supplied from the aftershield portion 47 through the gas supply pipe 49. The supplied shielding gas G convects in the torch surrounding space 61 surrounded by the sheet member 37 . Specifically, since the shielding gas G such as argon or carbon dioxide gas has a higher specific gravity than air, it accumulates below the torch surrounding space 61 . On the other hand, an opening 37 a is provided on the torch base end side (upper side in FIG. 4 ) of the sheet member 37 , and fumes during welding and surplus shielding gas G are discharged from the torch surrounding space 61 .

On the other hand, the widened tip edge 37b of the sheet member 37 is in contact with or extends to a position close to the base plate 25 or the floor surface 63, so the gap area from the tip edge 37b to the base plate 25 or the floor surface 63 is smaller than the opening area of the opening 37a. Therefore, the shielding gas G is suppressed from leaking from the leading end edge 37 b of the sheet member 37 and continues to stay below the torch surrounding space 61 . As a result, the welded portion and the weld end portion are always covered with the shielding gas G, improving the shielding property from the atmosphere.

FIG. 5A is an explanatory diagram schematically showing a state in which the gas shield jig 31 is held at the lowered position, and FIG. 5B schematically shows a state in which the gas shield jig 31 is held at the raised position.
As shown in FIG. 5A, when the gap between the leading edge 37b of the sheet member 37 of the gas shield jig 31 and the floor surface 63 (or the base plate) is narrow (gap distance H1), the supplied shielding gas G stays once in the lower part of the torch surrounding space 61 surrounded by the sheet member 37, and then is discharged from the upper opening 37a.

On the other hand, as shown in FIG. 5B, when the gap between the tip edge 37b of the sheet member 37 of the gas shield jig 31 and the floor surface 63 (or the base plate) is wide (gap distance H2), the supplied shielding gas G is also discharged from the lower gap, and the residence time in the torch surrounding space 61 is shortened. Therefore, by sliding the gas shield jig 31 in the axial direction of the torch and adjusting the gap with the floor surface 63 (or the base plate), the welding environment conditions such as the concentration, pressure, and replacement frequency of the shield gas G in the torch surrounding space 61 can be changed. According to this, the welding conditions can be optimized according to the object to be welded, and the welding quality can be improved.

Further, as shown in FIG. 5B, by moving the gas shield jig 31 in the axial direction of the torch 23, even if an obstacle exists in the movement path of the torch 23, interference with the obstacle can be reduced or prevented. Therefore, it is possible to improve the degree of freedom in the shape of the laminate-molded article without restricting the design of the trajectory of the welding path. Further, by moving the gas shield jig 31 upward and exposing the torch 23 from the gas shield jig 31, there is an advantage that maintenance of the torch 23 is facilitated. In this case, foreign matters such as spatters accumulated on the surface of the torch 23 can be easily removed.

Furthermore, the gas shield jig 31 has a structure that can be flexibly deformed. In other words, the skeleton member 35 has an elastic restoring force that restores the original shape due to its own elasticity when the shape bent by the external force is released.

The skeletal member 35 only needs to be strong enough to maintain the shape of the sheet member 37, and is composed of metal wires such as steel wires, piano wires, hard steel wires, stainless wires, and resin wires. Further, it is not limited to the wire material, and may be composed of a band material, a plate material, or the like alone or in combination.

(A) and (B) of FIG. 6 are explanatory diagrams showing how the skeleton member 35 of the gas shield jig 31 is deformed.
As shown in FIG. 6A, a spring 64 may be provided on part of the support piece 35a. In that case, the skeleton member 35 can be flexibly deformed even when an external force F is applied as shown in FIG. 6B. The spring 64 may be provided not only on the support piece 35a but also on the first annular portion 35b, the second annular portion 35c, and the strut portion 35d. Also, in addition to the spring 64, a damper or other elastically deformable mechanism may be provided.

FIG. 7 is an explanatory view schematically showing how the gas shield jig 31 moves while bending along the torch track.
Since the frame member 35 shown in FIG. 6 is flexibly deformable, the gas shield jig 31 can move while covering the space around the torch with the sheet member 37 even when obstacles 65 and 67 are present along the welding direction TD. Therefore, even when obstacles 65 and 67 exist, welding can be stably continued in a shield gas atmosphere. In addition, since the skeleton member 35 is formed in an annular (substantially circular) shape, it is possible to reliably secure the space around the torch and maintain the gas shielding property regardless of the direction in which the obstacle exists.

Furthermore, by sliding the gas shield jig 31 along the axial direction of the torch 23, interference with the obstacles 65 and 67 can be further reduced. The slide operation of the gas shield jig 31 can be performed by specifying the timing, position, and amount of slide from the information of the torch trajectory based on the stacking plan prepared in advance. Also, the surroundings of the torch 23 may be captured by a camera during welding, and the timing, position, and amount of sliding described above may be determined in real time so as to avoid obstacles recognized from the captured image information.

The present invention is not limited to the above-described embodiments, and combinations of the configurations of the embodiments with each other, modifications and applications by those skilled in the art based on the description of the specification and well-known techniques are also contemplated by the present invention and are included in the scope of protection.

As described above, this specification discloses the following matters.
(1) A gas shield jig provided in a gas shield welding torch for welding in a shield gas atmosphere and shielding the surroundings of the welded part from the atmosphere,
a support fixed to the torch;
a skeletal member that is elastically deformably held by the support portion and arranged to surround the torch;
a sheet member provided to cover the frame member and surround the torch;
with
The skeleton member has a shape that widens along the axis of the torch from the torch proximal end side toward the torch distal end side,
The sheet member is a gas shield jig having an opening on the base end side of the torch.
According to this gas shield jig, although it is inexpensive and has a simple structure, it is possible to retain the shield gas in the inner space of the sheet member, and even if there is an obstacle in the moving path of the torch, the skeleton member is elastically deformed according to the obstacle, so that the welding part can be reliably covered with the shield gas and welded. As a result, the welding quality is improved and the torch movement path is less restricted, increasing the degree of freedom in trajectory planning.

(2) The gas shield jig according to (1), wherein the support section includes a slide mechanism for moving the frame member and the sheet member along the axis of the torch.
According to this gas shield jig, by sliding the gas shield jig along the axis of the torch according to surrounding obstacles, it is possible to proceed welding while easily avoiding interference with the obstacles. Also, the semi-sealed environment of the shielding gas in the inner space of the sheet member can be easily adjusted.

(3) The gas shield jig according to (1) or (2), which includes a gas supply unit that supplies a shielding gas to the inner space of the sheet member.
According to this gas shield jig, the shield gas can be efficiently supplied to the inner space of the sheet member together with the shield gas supplied from the torch.

(4) The gas shielding jig according to (3), wherein the gas supply section includes an aftershield section that is disposed on the side of the torch and covers a welding end portion, and a gas supply pipe that supplies shielding gas to the aftershield section.
According to this gas shield jig, the welding end portion can be reliably covered with the shield gas, and the welding quality can be improved more reliably.

(5) The gas shield jig according to any one of (1) to (4), wherein the skeleton member has an elastic restoring force such that a shape bent by an external force returns to its original shape due to its own elasticity when the external force is released.
According to this gas shield jig, even if the frame member is deformed, it can be elastically restored. Therefore, as the torch moves, obstacles can be flexibly avoided and smooth welding can be performed.

(6) The gas shield jig according to any one of (1) to (5), wherein the frame member includes at least one support piece whose base end side is held by the support portion, a first annular portion connected to the tip end side of the support piece, a second annular portion arranged closer to the torch tip side than the first annular portion and having a larger diameter than the first annular portion, and a plurality of struts connecting the first annular portion and the second annular portion.
According to this gas shield jig, a large inner space of the sheet member can be secured by making the framework member into a frustum shape.

(7) The gas shield jig according to any one of (1) to (6), wherein the sheet member has an extension further extending from the flared tip edge of the frame member.
According to this gas shield jig, since the extending portion is arranged so as to extend forward from the frame member, the gap between the jig and the floor surface or the like becomes small, and leakage of the shield gas is suppressed.

(8) The gas shield jig according to any one of (1) to (7), wherein the sheet member is translucent.
According to this gas shield jig, the state of the welded portion inside the sheet member can be visually recognized, and the welding state can be easily monitored.

(9) The gas shield jig according to any one of (1) to (8), wherein the sheet member is a fireproof sheet or a flameproof sheet.
According to this gas shield jig, damage due to heat from the torch can be suppressed.

(10) A gas shield welding apparatus, wherein the torch for gas shield welding for welding in a shield gas atmosphere is provided with the gas shield jig according to any one of (1) to (9).
According to this gas shield welding device, when the gas shield jig moves following arbitrary movement of the torch, the gas shield jig is deformable, so that the surroundings of the torch can be reliably covered with the shield gas without restricting the movement of the torch.

Reference Signs List 11 welding robot 13 robot controller 15 filler metal supply section 17 shield gas supply section 19 welding power supply 21 control section 23 torch 25 base plate 29 welding bead 31 gas shield jig 33 support section 35 framework member 35a support piece 35b first annular section 35c second annular section 35d strut section 37 sheet member 37a opening Part 37b Leading Edge 39 Gas Supply Part 41 Fixing Bracket 43 Supporting Shaft 45 Slider 47 After Shield Part 49 Gas Supply Pipe 51 Case 51a Opening 51b Bottom 53 Wire Mesh 55 Rectification Body 57 Connection Part 59 Space 61 Torch Surrounding Space 64 Spring 100 Gas Shield Welding Apparatus W Laminate Model

Claims (10)

A gas shield jig provided in a torch for gas shield welding that welds in a shield gas atmosphere and shields the surroundings of the welded part from the atmosphere,
a support fixed to the torch;
a skeletal member that is elastically deformably held by the support portion and arranged to surround the torch;
a sheet member provided to cover the frame member and surround the torch;
with
The skeleton member has a shape that widens along the axis of the torch from the torch proximal end side toward the torch distal end side,
The sheet member is a gas shield jig having an opening on the base end side of the torch. 2. The gas shield jig according to claim 1, wherein the support portion includes a slide mechanism for moving the frame member and the sheet member along the axis of the torch. 3. The gas shield jig according to claim 1, further comprising a gas supply unit for supplying a shielding gas to the inner space of the sheet member. 4. The gas shield jig according to claim 3, wherein the gas supply section includes an after-shield section that is arranged on the side of the torch and covers a welding end portion, and a gas supply pipe that supplies shield gas to the after-shield section. The gas shield jig according to any one of claims 1 to 4, wherein the frame member has an elastic restoring force such that a shape bent by an external force returns to its original shape due to its own elasticity when the external force is released. The gas shield jig according to any one of claims 1 to 5, wherein the frame member has at least one support piece whose base end side is held by the support portion, a first annular portion connected to the tip side of the support piece, a second annular portion arranged closer to the torch tip side than the first annular portion and having a larger diameter than the first annular portion, and a plurality of struts connecting the first annular portion and the second annular portion. The gas shield jig according to any one of claims 1 to 6, wherein the sheet member has an extending portion further extending from the flared tip edge of the frame member. The gas shield jig according to any one of claims 1 to 7, wherein the sheet member has translucency. The gas shield jig according to any one of claims 1 to 8, wherein the sheet member is a fireproof sheet or a flameproof sheet. A gas shield welding apparatus, wherein the torch for gas shield welding for welding in a shield gas atmosphere is provided with the gas shield jig according to any one of claims 1 to 9.

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