JP7463427B2 - Welding Equipment - Google Patents

Description

The present invention relates to a welding device.

The technology described in Patent Document 1 is known as a technique for butt welding two pieces of pipe (steel pipe). Patent Document 1 describes an automatic welding device that welds in the circumferential direction of the pipe while rotating a welding means (torch) around the axis of the pipe.

JP 2006-334617 A

In the technology of Patent Document 1, as shown in Figures 12 and 13, when welding with a torch 100, molten metal tends to sag due to gravity and solidify in a biased state at the bottom of the pipe P. Between the excess weld height H1 of the bead 101 at the top of the pipe P and the excess weld height H2 at the bottom, the excess weld height H2 at the bottom is greater, and there is a concern that the excess weld height in the circumferential direction will be uneven. The objective of the present invention is to provide an automatic welding device that suppresses the bias of the molten metal in the circumferential direction and makes the excess weld height uniform.

A welding device for butt welding pipes includes a welding head, a head holder for holding the welding head, and a positioner for rotating the head holder in the circumferential direction of the pipes. The welding head includes a fixing part for fixing the pipes to the welding head, an electrode for discharging electricity toward the pipes to perform welding, and a drive part for rotating the electrode in the circumferential direction of the pipes fixed by the fixing part and in the opposite direction to the rotation of the head holder by the positioner. The drive part rotates the electrode so that the direction of the electrode as seen from the pipes is maintained by offsetting the rotation of the head holder with the rotation of the electrode. The electrode is positioned above the axis of the pipes and discharges electricity downwards onto the pipes to perform welding in the circumferential direction of the pipes.

In this configuration, the pipe is rotated in a circumferential direction while an electrode that maintains an upper position relative to the pipe discharges electricity downward to weld the top of the pipe. As the pipe rotates, the pipe is welded in the circumferential direction. The molten metal generated at the top of the pipe rotates with the pipe, but it cools and solidifies before reaching the side of the pipe, so it is less likely to sag.

This prevents the molten metal from shifting to one side, making the height of the weld metal uniform in the circumferential direction. By making the height of the weld metal uniform around the entire circumference, it becomes easier to ensure that the weld metal penetrates the inner surface of the pipe, and the problem of insufficient throat thickness can be eliminated.

The position of the electrode relative to the pipe may be within a range of -45° to +45° centered on the axis, with 0° being vertically above the axis as viewed from the axial direction of the pipe.

This further reduces the drooping of the molten metal and makes the height of the excess fill more uniform in the circumferential direction.

The welding head may have an annular ring that rotates around the axis of the pipe, the axis of rotation of the ring overlapping the axis, and the electrode may extend from the inner wall of the ring toward the axis.

Because the center of rotation of the electrode is located on the axis of the pipe, it is easy to maintain a constant distance between the electrode and the pipe surface, ensuring stable welding quality.

The positioner may have a detector that detects the current flowing through the electrode when welding begins, and may start rotating the head holder when the detector detects the current.

Since the positioner can automatically start rotating when welding begins, it is possible to reduce variation in the time difference between when the welding head starts welding and when the positioner starts rotating, stabilizing the quality of the welded area.

According to the present invention, it is possible to make the height of the excess weld uniform in the circumferential direction when butt welding pipes.

Side view of the welding device (viewed from the Y direction) Plan view of welding equipment Side view of the welding device (viewed from the X direction) A block diagram showing the electrical configuration of a welding device. Side view of the welding head (viewed from the X direction) A-A cross-sectional view of the welding head Cross-sectional view showing the welding process (1) Cross-sectional view showing the welding process (2) Cross-sectional view showing the welding process (3) Cross-sectional view showing the welding process (4) Close-up of welded area Diagram showing welding according to the prior art Close-up of a welded area using conventional technology

1. Configuration of the Welding Apparatus An embodiment of the present invention will be described with reference to Figs. 1 to 11. The welding apparatus 1 is an apparatus that butts open ends of pipes P1 and P2 arranged along an axis and welds them in the circumferential direction (see Fig. 6). The welding apparatus 1 includes stands 10A and 10B, a head holder 20, a welding head 30, a welding machine main body 51 (see Fig. 4), a positioner 60, and the like. In the following description, the pipes P1 and P2 may be simply referred to as pipes P. The axis of the pipe P is the axis C1, and the rotation axis of the positioner 60 is the axis C2.

The direction parallel to axis C1 is the X direction, the vertical direction is the Z direction, and the direction perpendicular to both the X and Z directions is the Y direction.

<Frame>
1 to 3, a pair of rollers 11 having a rotation axis parallel to the X direction are provided on the upper surface of the base 10A. The pair of rollers 11 are spaced apart in the Y direction. The base 10B has a top plate, and a positioner 60 is placed on the top plate. The rollers 11 and the positioner 60 support the head holding unit 20.

<Head holding part>
1 to 3, the head holding part 20 includes a pair of cylindrical parts 21A, 21B, a frame 22, an arm 23, and a head fixing part 24. The frame 22 is in the shape of a rectangular frame and includes a pair of parallel long side parts 25 extending in the X direction, and a pair of parallel short side parts 26 connecting both ends of the long side parts 25 to each other.

Cylindrical parts 21A and 22B are connected to the pair of short sides 26, each of which extends toward the outside of the frame 22 and has its axis in the X direction. Cylindrical part 21A is rotatably supported by rollers 11. Cylindrical part 21B is fixed to a rotating plate 61 of a positioner 60. The heights of the mounts 10A and 10B are adjusted so that the heights of the axes of cylindrical parts 21A and 21B are the same. The axes of cylindrical parts 21A and 21B are aligned on the axis C2 of the rotating plate. The diameters of cylindrical parts 21A and 21B may be different.

The arm 23 is connected to the long side portion 25. As shown in FIG. 3, the arm 23 is configured by connecting a first arm 23A, a second arm 23B, and a third arm 23C in sequence.

The base end of the first arm 23A is connected to any point on the long side 25, and extends in a direction perpendicular to both the long side 25 and the short side 26. The base end of the second arm 23B is connected to the tip of the first arm 23A. The second arm 23B extends in a direction parallel to the short side 26, and a third arm 23C is connected to its tip. A head fixing part 24 is attached to the third arm 23C. The head fixing part 24 is, for example, a clamp, and fixes the welding head 30 (described later) by clamping it from both sides in the X direction.

The length of each part of the arm 23 is adjusted so that the axis C1 of the pipe P fixed to the welding head 30 and the axis C2, which is the rotation axis of the positioner 60, overlap when viewed from the X direction.

The welding head 30 is fixed to the frame 22 via the head fixing part 24 and the arm 23. When the positioner 60 rotates the head holding part 20, the head holding part 20 and the welding head 30 rotate together around the axis C2.

<Automatic welding machine>
The automatic welding machine 50 is a device that receives power from a power source S via a power cable 54 and automatically performs butt welding of a pipe P. As shown in FIG. 4 , the automatic welding machine 50 has a welding machine main body 51 and a welding head 30.

The welding machine main body 51 has a control unit 52 and an input unit 53. The control unit 52 controls the operation of the welding head 30 based on a preset welding program or instructions input by the operator via the input unit 53. By operating the input unit 53, the operator can instruct the control unit 52 to start or stop welding, change the welding program, etc. The welding program includes the magnitude of the current to be passed through the electrode 36, which will be described later, and the angular velocity ω1 of the electrode 36.

The welding head 30 is a welding head that performs TIG welding. FIG. 5 is a side view of the welding head 30 as viewed from the X direction. As shown in FIG. 5, the welding head 30 has a head body 31, a head cover 32, a ring drive unit (an example of a drive unit) 33, a ring 34, a head cable 35, and an electrode 36.

The head body 31 is a box-shaped member with one end (the left side in FIG. 5) open. A hinge 37 is provided below the opening. The head body 31 and the head cover 32 are connected via the hinge 37. The head cover 32 can rotate around the axis of the hinge 37, allowing the opening of the head body 31 to be opened and closed.

A portion of the opening end of the head body 31 is cut out in a semicircular shape to form a body recess 31A. A portion of the head cover 32 facing the body recess 31A is also cut out in a semicircular shape to form a cover recess 32A. When the head cover 32 is closed, the semicircular body recess 31A and cover recess 32A are connected to form a single circular opening.

The diameter of the opening is approximately the same as the outer diameter of the pipe P to be welded. By closing the head cover 32 and clamping the pipe P between the head body 31 and the head cover 32, the pipe P can be fixed to the welding head 30.

The head body 31 and head cover 32 have the same configuration on the opposite side (opposite side in the X direction). The welding head 30 can clamp one pipe P on each side in the X direction and fix the pipes P1 and P2 in a butted state (see Figure 6). The head body 31 and head cover 32 are an example of a fixing part.

The head body 31 houses a ring drive unit 33 and a ring 34. The ring drive unit 33 is, for example, an electric motor, and receives power from the head cable 35 to generate a driving force. The driving force generated by the ring drive unit 33 is transmitted to the ring 34 via gears, belts, etc., and rotates the ring 34 around the axis C1 of the pipe P.

The ring 34 is annular, with a needle-shaped electrode 36 extending from the inner peripheral wall toward the center. As the ring 34 rotates, the electrode 36 rotates about the axis C1 while maintaining a constant distance between the tip of the electrode 36 and the pipe P. The electrode 36 rotates while generating an arc between the electrode 36 and the pipe P due to power supplied via the head cable 35, welding the pipe P in the circumferential direction.

<Positioner>
The positioner 60 is placed on the pedestal 10B and includes a rotating plate 61, an input unit 62, a control unit 63, a driving unit 64, a detector 65, etc. (see FIGS. 1 and 4). The positioner 60 is a single-axis positioner that rotates the rotating plate 61 around an axis C2 by the driving force of the driving unit 64.

The input unit 62 is an input device including buttons and switches that allow the operator to operate the positioner 60. The control unit 63 controls the operation of the drive unit 64 based on the information input to the input unit 62. The operator can start and stop the rotation of the rotating plate 61 by operating the input unit 62. The operator can also operate the input unit 62 to switch the rotation direction of the rotating plate 61 and arbitrarily change the rotation speed (angular velocity ω2).

As described above, the cylindrical portion 21B of the head holding portion 20 is fixed to the rotating plate 61. The operator can rotate the head holding portion 20 around the axis C2, which is the rotation axis of the rotating plate 61, at any angular velocity ω2 and in any rotation direction by manipulating the input unit 62. In this embodiment, the angular velocity ω2 is set to be the same magnitude as the angular velocity ω1 of the electrode 36, but in the opposite direction.

The detector 65 has a sensor 65A and detects the current flowing through the power cable 54. As the sensor 65A, for example, a magnetic field detection type sensor that detects the current from the strength of the magnetic field generated around the power cable 54 is used.

The sensor 65A attached to the power cable 54 detects the magnetic field generated by the current flowing through the power cable 54. When the magnetic field strength reaches or exceeds a preset threshold, the detector 65 sends an ON signal to the control unit 63. Upon receiving the ON signal, the control unit 63 immediately drives the drive unit 64 to start rotating the head holding unit 20.

This reduces and stabilizes the lag between the timing when the automatic welding machine 50 starts welding by the operator and the timing when the positioner 60 starts rotating, making the welding quality stable.

The threshold current value set in the detector 65 is set to a value that is greater than the current that flows when only the ring drive unit 33 is operating, and is smaller than the current value when the ring drive unit 33 is not operating and the electrode 36 is discharging and welding is being performed.

2. Welding Operation Next, the operation of the welding device 1 according to this embodiment when butt welding the pipe P will be described with reference to Figures 7 to 11. For simplification, Figures 7 to 10 only show the head holder 20, the welding head 30, and the pipe P.

Figure 7 shows the initial state before welding begins. Figure 7(a) shows the appearance of the head holder 20 and the welding head 30, and Figure 7(b) shows the positional relationship of the electrode 36 and the pipe P inside the welding head 30. The same is true for Figures 8(a)(b) and 9(a)(b).

In order to make it easier to understand the rotation of the head holding unit 20, in the initial state shown in FIG. 7(a), the short side 26 of the head holding unit 20 is parallel to the Z direction.

In the following description, the direction vertically above the axis C1 in FIG. 7(b) is defined as 0°, and angles counterclockwise around the axis C1 are expressed as + (plus) and angles clockwise around the axis C1 are expressed as - (minus). The direction and position of the electrode 36 relative to the pipe P are expressed using the angle around the axis C1. For example, the electrode 36 shown in FIG. 7(b) is expressed as "0° direction" or "0° position".

Before welding begins, the operator operates the input unit 53 of the automatic welding machine 50 to rotate the ring 34 and move the electrode 36 to the 0° position (initial state in FIG. 7(b)). Discharge by the electrode 36 then begins, and downward welding begins. The electrode 36 rotates at an angular velocity ω1 relative to the welding head 30 (arrow 70). The position on the outer periphery of the pipe P where welding begins is defined as the welding start position PA. In this embodiment, the welding start position PA is set to the 0° position on the outer periphery, but the welding start position PA may be any position above the axis C1 of the pipe P (i.e., in the range of -90° to +90°).

The detector 65 detects the current flowing through the power cable 54 when discharge begins, and sends an ON signal to the control unit 63. In response to the ON signal, the control unit 63 drives the drive unit 64 to rotate the head holding unit 20 at an angular velocity ω2 (arrow 71).

Figures 8(a) and (b) show the state when the head holding part 20 is rotated +45° from the initial state. The head holding part 20, the welding head 30 held by the head holding part 20, and the pipe P fixed to the welding head 30 rotate together. In contrast, the ring 34 and the electrode 36 rotate -45° inside the welding head 30.

The rotation of the head holder 20 (and pipe P) and the rotation of the electrode 36 are offset, and the direction of the electrode 36 is maintained at 0°, unchanged from the initial state, and downward welding continues. Meanwhile, the pipe P has rotated +45° together with the head holder 20, so the outer circumference of the pipe P is welded over 45°, and a bead 72 of 45° is formed from the welding start position PA to directly below the electrode 36.

9(a) and (b) show the state when the head holder 20 is rotated further by +45° (+90° from the initial state). Because the rotation of the head holder 20 (and the pipe P) and the rotation of the electrode 36 are offset, the direction of the electrode 36 as seen from the pipe P remains unchanged at 0° from the initial state. Meanwhile, the pipe P has been rotated further by +45° together with the head holder 20 from the state shown in FIG. 8, so that the outer circumference of the pipe P is welded by a total of 90°, and a bead 72 of 90° is formed from the welding start position PA to directly below the electrode 36. After this, the rotation of the head holder 20 and the welding by the welding head 30 are continued, and the direction of the electrode 36 as seen from the pipe P is maintained from the initial state, and the outer circumference of the pipe P is welded one or more times (for example, two times), completing the butt welding of the pipe P.

3. Description of Effects Fig. 10 is an enlarged view of the pipe P and the electrode 36 in Fig. 9(b) . In the upper part of the pipe P in the vicinity of the electrode 36, the pipe P is heated by the arc generated from the electrode 36, and molten metal is produced.

Point A of the bead 72, located at the top of the pipe P, is hot and has a large amount of molten metal because it has just passed near the electrode 36. On the other hand, at point B, some time has passed since it passed under the electrode 36, so the temperature of the molten metal is lower than at point A and the solidification of the metal has progressed more than at point A.

At point A at the top of the pipe, the slope is gentle, so the molten metal is less likely to droop. At point B, the slope is steeper than at point A, but the metal has solidified more than at point A, so the molten metal is less likely to droop in any direction around the pipe. The configuration of this embodiment suppresses the drooping of molten metal caused by welding, and prevents the molten metal from flowing in the circumferential direction and becoming concentrated in a specific location.

Figure 11 shows a pipe P that has been butt-welded using the welding device 1 of this embodiment. The bead 72 has approximately the same height H3 at the top of the pipe and H4 at the bottom. With the configuration of this embodiment, the bead height can be made uniform in the circumferential direction compared to welding using conventional technology (see Figures 12 and 13).

In addition, by making the excess weld height uniform, it becomes easier to ensure penetration to the inner surface of the pipe P, and insufficient throat thickness can be eliminated. This increases the strength of the welded area.

In addition, the welding head 30 included in the welding device 1 can be an existing welding head used in welding using conventional technology. Therefore, the welding device 1 of this embodiment can be introduced at low cost.

<Other embodiments>
The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments, for example, are also included within the technical scope of the present invention.

(1) In the above embodiment, a welding head 30 that performs TIG welding is illustrated, but a welding head that performs welding by a method other than TIG welding may be used. Also, a welding head that feeds a filler metal to the welding point may be used.

(2) In the above embodiment, a detector 65 is attached to the power cable 54 connecting the power source S and the automatic welding machine 50 to detect the start of welding. However, the detector 65 may not be provided and the operator may manually start the rotation of the positioner 60. In this case, the operator manually operates both the input unit 53 of the automatic welding machine 50 and the input unit 62 of the positioner 60 so that welding by the welding head 30 and the rotation of the positioner 60 are performed in parallel.

(3) In the above embodiment, the detector 65 is provided to detect the current in the power cable 54 connecting the power source S and the automatic welding machine 50, but the detector 65 may be provided in another location. For example, the detector 65 may be provided in the head cable 35 connecting the welding machine main body 51 and the welding head 30. The detector 65 may also be provided inside the welding machine main body 51.

(4) In the above embodiment, the frame 22 of the head holding part 20 is shaped like a rectangular frame, but the shape of the frame 22 is not limited to this. For example, the frame may be a crank-shaped frame consisting of two short sides 26 and one long side 25. It may also be a shape that linearly connects the cylindrical parts 21A and 21B. In other words, the head holding part 20 may be configured to hold the welding head 30 and rotate the welding head 30 around the axis C2.

(5) In the above embodiment, a magnetic field detection sensor is used as the detector 65, but the current flowing through the power cable 54 may be detected by other methods. A detector connected in series to the power cable 54 may also be used.

(6) In the above-described embodiment, the axis C1 of the pipe P and the axis C2 of the positioner 60 (and the head holding portion 20) overlap when viewed from the X direction, but the axis C1 and the axis C2 do not have to overlap.

(7) In the above embodiment, the rotation direction of the head holding portion 20 and the rotation direction of the electrode 36 are the directions of the arrows 71 and 70 shown in FIG. 7, respectively, but they may be opposite rotation directions.

(8) In the above embodiment, an example was given of welding in the circumferential direction of the pipe P while maintaining the electrode 36 at a position of 0° relative to the pipe P, but the position of the electrode 36 during welding is not limited to 0°, and the position may also change during welding. The electrode 36 may be maintained in a state positioned above the axis C1 of the pipe P and welding may be performed downward. Specifically, the electrode 36 may be positioned in the range of -90° to +90° during welding, and a range of -45° to +45° is particularly desirable.

(9) In the above embodiment, the control unit 63 starts rotating the head holding unit 20 immediately after receiving the ON signal from the detector 65, but the rotation of the head holding unit 20 may start at any timing after receiving the ON signal. For example, even if welding by the electrode 36 is started, the head holding unit 20 may not be rotated immediately after receiving the ON signal, but may start rotating after welding is performed at a predetermined angle in the circumferential direction. In addition, the rotation of the head holding unit 20 may start a predetermined time after receiving the ON signal. The start of rotation of the head holding unit 20 can be set to any timing after receiving the ON signal by the operator operating the input unit 62 or by the operator setting the operation program of the positioner 60 in advance.

1: Welding device 10A, 10B: Stand 11: Roller 20: Head holder 30: Welding head 34: Ring 35: Head cable 36: Electrode 54: Power cable 60: Positioner 61: Rotating plate 65: Detector P: Pipe

Claims (5)

A welding device for butt welding piping,
A welding head;
a head holder for holding the welding head;
a positioner that rotates the head holding portion in a circumferential direction of the pipe,
The welding head includes:
a fixing portion that fixes the pipe to the welding head;
an electrode that discharges electricity toward the pipe to perform welding;
a drive unit that rotates the electrode in a circumferential direction of the pipe fixed by the fixing unit and in a direction opposite to the rotation of the head holding unit by the positioner,
the driving unit rotates the electrode such that a direction of the electrode as viewed from the pipe is maintained by offsetting a rotation of the head holding unit with the rotation of the electrode;
The electrode is positioned above the axis of the pipe and discharges electricity downward onto the pipe to weld the pipe in the circumferential direction. 2. The welding apparatus of claim 1,
A welding device in which the position of the electrode with respect to the pipe is within a range of -45° to +45° centered on the axis, with 0° being vertically above the axis as viewed from the axial direction of the pipe. 2. The welding apparatus of claim 1,
The welding head has an annular ring that rotates around the axis of the pipe,
The rotation axis of the ring overlaps with the axis line,
The electrode extends from an inner circumferential wall of the ring toward the axis. The welding device according to claim 2,
The welding head has an annular ring that rotates around the axis of the pipe,
The rotation axis of the ring overlaps with the axis line,
The electrode extends from an inner circumferential wall of the ring toward the axis. A welding device according to any one of claims 1 to 4,
The positioner has a detector that detects a current flowing through the electrode when welding starts,
A welding device in which the positioner starts rotating the head holding portion when the detector detects a current.

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