JP2002079376A - Welding equipment for manufacturing pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide welding equipment for manufacturing a pipe, with which stable welding beads with satisfactory quality are continuously produced in all the welding speeds of a low speed and a high speed from a stop state. SOLUTION: In the welding equipment for manufacturing the pipe, which is equipped with squeeze rolls butting tip parts along the length direction of the pipes to be transferred, which are not welded yet and a welding torch welding the above tip parts, a means adjusting the tilt angle of the welding torch according to a welding speed, is provided on the above welding torch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe welding apparatus, and more particularly to a pipe welding apparatus capable of forming a long pipe, and continuously obtaining a stable and high-quality weld bead even at a low or high welding speed. The present invention relates to a pipe welding device.

[0002]

2. Description of the Related Art Generally, when a welded metal pipe (welded pipe) is manufactured from a metal plate (hereinafter simply referred to as pipe making), the metal plate is first formed into a cylindrical shape continuously by a forming roll or the like. Then, a substantially circular welded pipe is manufactured by melting an end portion of the butted metal plate with a welding arc (hereinafter simply referred to as an arc) while applying pressure with an appropriate force.

FIG. 7 is a plan view of a conventional pipe making apparatus. FIG. 8 is a front view of the pipe manufacturing apparatus of FIG. 31
Is an unwelded pipe, 32 is a butt portion, 33 is a first squeeze roll, 34 is a second squeeze roll, 35 is a weld pipe, 36 is a weld bead, 37 is a welding torch, 38 is a welding machine, and 39 is a gantry.

[0004] The pipe making apparatus includes a first squeeze roll 33.
, A welding torch 37, a welding machine 38, a second squeeze roll 34, and a gantry 39 for holding the first squeeze roll 33 and the second squeeze roll 34.

[0005] The metal plate is continuously formed into a cylindrical shape by a forming roll or the like, and is introduced into a tube manufacturing apparatus shown in FIG. Here, a forming roll for forming a metal plate into a cylindrical shape may be included in the pipe manufacturing apparatus. The butted end of the unwelded pipe 31, that is, the butted portion 32, is melted and integrated by an arc generated from an electrode provided at the tip of the welding torch 37 while being held by the first squeeze roll 33. The arc is generated by a voltage applied to the electrode from the welding machine 38.

A constant pressing force is applied to the welded portion by the second squeeze roll 34 so that the welded portion is not separated by a force such as spring back of the tube after the unification, and naturally cools as the distance from the welding torch 37 increases. Then the pipe making is completed. A weld bead 36 is formed in the portion that has been fused and integrated, that is, the welded portion.

[0007] The characteristics required for the metal pipe by welding are that the height of the weld bead portion is low and uniform, the width of the weld bead is sufficient, and no cracks or bubbles are contained inside the weld portion. And the like.

The angle of the welding torch 37 or the electrode is generally perpendicular to the surface to be welded (the butt 32), but the higher the welding speed, the more unstable the arc becomes. As shown in FIG. 9, a state in which the joining can be performed only near the surface of the metal pipe, or a state in which a recess like a groove is formed at both ends of the weld bead as shown in FIG. 9 occur. The state of FIG. 9 is called an undercut. for that reason,
The welding torch 37 or the electrode is connected to the unwelded pipe 31.
It is arranged and fixed at a specific angle in the welding direction toward the side.

[0009]

However, the conventional pipe welding apparatus has the following problems.

[0010] Since the angle of inclination of the welding torch or the electrode is fixed, the angle of the arc is fixed and cannot cope with a wide range of welding speeds. There was a problem to say.

If the inclination angle of the welding torch is set to an optimum condition for low-speed welding in order to secure the stability of low-speed welding, defects such as undercut and weld skip occur when the welding speed is high. I was

FIG. 9 is an explanatory view of a pipe welded portion (when there is an undercut) by a conventional pipe making apparatus.
40 is a pipe base material part, and 41 is a pipe welding part. When the welding speed is high, the welding current becomes large, so that a recess like a groove is formed at both ends of the weld bead, that is, an undercut occurs.

FIGS. 10 and 11 are explanatory views of a pipe welded portion (in the case where there is a weld skip (including joining only near the surface of a metal pipe)) by a conventional pipe welding apparatus. 42,
44 is a pipe base material, and 43 and 45 are pipe welds. When the welding speed is high, the arc is caused to flow in the traveling direction, and the pipe cannot be joined or the pipe is joined only near the surface, so-called weld skip is observed.

A welded pipe having an undercut or a weld skip as shown in FIGS. 9 and 10 cannot be used as a product because the reliability of the welded portion of the pipe is significantly reduced.

[0015] In short, in the conventional pipe welding apparatus,
Since the torch inclination angle (or electrode inclination angle) setting is suitable for a specific range of welding speed, the success rate of arc start is reduced, and stable quality is obtained at either low speed welding or high speed welding speed. It was not possible to obtain good weld beads continuously.

Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to continuously produce a stable and high-quality weld bead at all welding speeds from a stopped state to a low speed and a high speed. Is to provide.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a squeeze roll for abutting ends of a conveyed unwelded pipe along the length thereof, and a welding torch for welding the ends. And a means for adjusting the inclination angle of the welding torch in accordance with the welding speed in the welding torch.

The means for adjusting the tilt angle includes a crankshaft directly connected to the welding torch, a gear for transmitting rotation to the crankshaft, a servomotor for rotating the gear, and measuring the rotation of the gear. An encoder, a speedometer for measuring a welding speed, and a control unit for sending a control signal to the servomotor were configured.

Further, the welding torch is configured such that the inclination angle uniformly increases or decreases with an increase or decrease of the welding speed, and returns to the initial set angle when welding is stopped.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of a pipe making and welding apparatus of the present invention, FIG. 2 is a front view of the pipe making and welding apparatus of FIG. 1, and FIG. 3 is a pipe making and welding apparatus of FIG. FIG. 1 is an unwelded pipe, 2 is a butt portion, 3 is a first squeeze roll, 4 is a second squeeze roll, 5 is a welded pipe, 6 is a weld bead, 7 is a welding torch, 8 is a crankshaft,
9 is a bearing, 10 is a gear, 11 is an encoder, 12 is a servomotor, 13 is a welding machine, 14 is a controller, 15 is a speedometer, and 16 is a gantry.

[0022] The pipe making apparatus includes a first squeeze roll 3
Welding torch 7, welding machine 13, second squeeze roll 4, gantry 16 holding first squeeze roll 3 and second squeeze roll 4, and crankshaft for controlling the inclination angle of welding torch 7. 8, bearing part 9, gear 1
0, encoder 11, servo motor 12, control unit 14,
And a speedometer 15.

The metal plate is continuously formed into a cylindrical shape by a forming roll or the like, and is introduced into the tube making apparatus shown in FIG. Here, a forming roll for forming a metal plate into a cylindrical shape may be included in the pipe manufacturing apparatus. The butted end of the unwelded pipe 1, that is, the butted part 2, is melted and integrated by an arc generated from an electrode provided at the tip of the welding torch 7 while being held by the first squeeze roll 3. The arc is generated by a voltage applied from the welding machine 13 to the electrode.

A constant pressing force is applied to the pipe welded portion by the second squeeze roll 4 so as not to be separated by a force such as springback of the raw tube after the fusion and integration, and as the pipe is separated from the welding torch 7, It is cooled to complete the pipe making. A weld bead 6 is formed at the portion that has been fused and integrated, that is, at the welded portion.

FIG. 4 is an explanatory view of a welding torch of the pipe making apparatus of FIG. 17 is an electrode, and θ is the angle of inclination of the welding torch or the electrode. When θ = 0, it means that the welding torch 7 is set perpendicular to the surface to be welded, that is, the butt portion 2. The welding torch 7 is set to an initial value (initial inclination angle) at the start of welding, that is, inclined at a specific angle in the welding progress direction with the electrode 17 facing the unwelded pipe 1 side, so that θ changes during pipe welding. Is configured. The initial tilt angle can be zero degrees.

FIG. 5 relates to a pipe welding apparatus according to the present invention.
FIG. 4 is a characteristic diagram showing a relationship between a welding speed and a torch inclination angle. The horizontal axis represents the welding speed V (m / min), and the vertical axis represents the torch inclination angle θ (degree). From various experimental results, the optimum torch inclination angle θ is θ = 2.5 · V + a. Here, a is an initial value (initial inclination angle) and is in the range of −12.5 ≦ a ≦ 25, the unit of θ is degrees, and the unit of V is m / min. Further, when θ obtained by the above equation becomes negative when a and V are substituted (−12.5 ≦ a ≦ 0 and V ≦ 5), θ is replaced by 0 in any case. The width of “a” depends on the material and dimensions of the workpiece and the working environment.
Therefore, it is necessary to determine the value of a in advance and start inputting the value to the control unit 14 before starting the pipe welding. The numerical value 2.5 in the expression representing the torch inclination angle θ represents an optimum value, and this numerical value can be changed within a range of 1.0 to 3.5.

The feature of the pipe-forming welding apparatus of the present invention is that the inclination angle of the welding torch is automatically changed in accordance with the welding speed, and a stable and high-quality welding bead can be obtained at all welding speeds from low to high speeds. To make it continuous,
Hereinafter, a method of controlling the inclination angle of the welding torch 7 will be described.

The value of a is input to the control unit 14 in advance. The servo motor 12 is controlled by a control signal from the control unit 14.
Rotates, and the rotation is transmitted to the welding torch 7 via the gear 10 and the crankshaft 8. Crankshaft 8
Is directly connected to the welding torch 7 and the crankshaft 8
Is rotated, the welding torch 7 is also rotated. A bearing 9 is provided for smooth rotation of the crankshaft 8. The rotation of the welding torch 7 can be measured by the encoder 11, and this information is also sent to the control unit 14. The speedometer 15 measures the welding speed.
Is installed near the welding pipe 5, for example.

At the start of welding, the controller 14 sets the initial inclination angle a
Is input and the welding torch 7 is set based on the value, and then pipe welding is started. Then, the welding speed is measured by the speedometer 15, and the information is sent to the control unit 14. From the received welding speed information, the optimum torch inclination angle is obtained based on the equation θ = 2.5 · V + a, and a control signal for inclining the welding torch 7 is sent to the servo motor 12. The servo motor 12 rotates as required, and the rotation is transmitted to the welding torch 7 via the gear 10 and the crankshaft 8 and set to the optimum inclination angle.

When the welding speed is increased during pipe welding, the welding torch is inclined and becomes horizontal in proportion to the welding speed, but exceeds 90 degrees, that is, the electrode is further inclined upward from the horizontal state. It will not be done. When the welding speed is reduced, the welding torch stands in proportion to the welding speed. And when welding stops, it is comprised so that it may return to an initial inclination angle. Accordingly, the optimum welding torch tilt angle is set regardless of the welding speed.

FIG. 6 is an explanatory diagram of a pipe welded portion by the pipe making apparatus of FIG. Reference numeral 18 denotes a pipe base material, and 19 denotes a pipe weld. A stable and high-quality weld bead is obtained regardless of the welding speed.

[0032]

According to the pipe welding apparatus of the present invention, there is provided a squeeze roll for abutting ends along a length direction of a conveyed unwelded pipe, and a welding torch for welding the ends. In the pipe making apparatus, the welding torch is provided with means for adjusting the inclination angle of the welding torch in accordance with the welding speed. Can be produced continuously, and the reliability of the weld is greatly improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a pipe welding apparatus according to the present invention.

FIG. 2 is a front view of the pipe welding apparatus of FIG.

FIG. 3 is a side view of the pipe making and welding apparatus of FIG.

4 is an explanatory view of a welding torch of the pipe making apparatus of FIG.

FIG. 5 is a characteristic diagram showing a relationship between a welding speed and a torch inclination angle in relation to the pipe forming welding apparatus of the present invention.

FIG. 6 is an explanatory view of a pipe welded portion by the pipe making apparatus of FIG. 1;

FIG. 7 is a plan view of a conventional pipe making welding apparatus.

8 is a front view of the pipe making apparatus of FIG. 7;

9 is an explanatory view of a pipe welded portion (when there is an undercut) by the pipe welding apparatus of FIG. 7;

10 is an explanatory diagram of a pipe welded portion (when there is a weld skip) by the pipe welding device of FIG. 7;

FIG. 11 is an explanatory view of a pipe welded portion by the pipe welding apparatus of FIG. 7 (in a case where joining can be performed only near the surface of a metal pipe).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unwelded pipe 2 Butt part 3 First squeeze roll 4 Second squeeze roll 5 Weld pipe 6 Weld bead 7 Welding torch 8 Crankshaft 9 Bearing 10 Gear 11 Encoder 12 Servo motor 13 Welding machine 14 Control unit 15 Speedometer 16 Mount 17 electrode 18 pipe base material part 19 pipe weld part 31 unwelded pipe 32 butted part 33 first squeeze roll 34 second squeeze roll 35 weld pipe 36 weld bead 37 welding torch 38 welder 39 gantry 40 pipe base material 41 pipe weld Part 42 Pipe base material part 43 Pipe weld part 44 Pipe base material part 45 Pipe weld part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B23K 101: 06 B23K 101: 06 (72) Inventor Koichi Kusakabe 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1 F-term in the Hidaka Plant of Hitachi Cable, Ltd. (reference) 4E081 AA04 DA18 EA29 EA45 FA03

Claims (3)

[Claims] 1. A pipe-forming welding apparatus comprising: a squeeze roll for abutting ends of a conveyed unwelded pipe along a length direction thereof; and a welding torch for welding said ends. Is a means for adjusting the inclination angle of the welding torch according to the welding speed. 2. A means for adjusting a tilt angle includes a crankshaft directly connected to the welding torch, a gear for transmitting rotation to the crankshaft, a servomotor for providing rotation to the gear, and measuring rotation of the gear. 2. The pipe welding apparatus according to claim 1, further comprising: an encoder that performs welding, a speedometer that measures a welding speed, and a control unit that sends a control signal to the servomotor. 3. The welding torch according to claim 1, wherein the inclination angle uniformly increases or decreases as the welding speed increases or decreases, and returns to the initial set angle when welding is stopped. Item 2. A pipe welding apparatus according to Item 1.