JP5741675B2 - Welding wire connection method - Google Patents

Description

  The present invention relates to a welding wire coupling method, and more particularly to a welding wire coupling method used for welding large diameter steel pipes having a thickness of 6 mm or more.

  A large-diameter steel pipe having an outer diameter of about 20 to 60 inches and a length of about 10 to 18 m is generally a thick plate (plate thickness: 6 to 50 mm) having a dimension corresponding to the outer diameter to be manufactured. After forming into O shape, it is manufactured by performing tack welding on the seam, and then performing submerged arc welding on the inner surface and the outer surface. Many welding wires are used in tack welding and inner and outer surface welding.

  Usually, when the length of the remaining portion of the welding wire is shorter than the sum of the amount of use per welding wire and the distance from the welding wire installation position to the welded portion, It is necessary to prepare a new welding wire (hereinafter referred to as “new wire”).

  The old wire is discarded or used by being joined to the new wire by butt welding. However, when the old wire is discarded, the amount of welding wire used is increased and the cost is increased. When the old wire is butt welded with the new wire, there is an unavoidable variation in the welding skill of the operator, which may cause operational troubles and degradation of the welding quality. In any case, since it is necessary to perform operations such as removal of the old wire and preparation of the new wire, the production efficiency is lowered.

So far, many methods for connecting the old wire and the new wire have been proposed.
In Patent Documents 1 to 6, when connecting the wires with projections and depressions, the projections are formed with protrusions, the projections are covered with caps, and the tips of the wires are subjected to recess processing, , One that connects with a convex jig having a ridge, one that uses a wedge-shaped irregularity on the wire tip, one that has a concave processing on the wire tip, and inserts a convex jig covered with an insulating material, A method has been disclosed in which after the concave processing is applied to the tip, they are connected by a convex jig having a ridge and then pressed.

Japanese Patent Application Laid-Open No. H10-228688 discloses that a concavo-convex wire connection having a connection length of 25 mm or more is performed.
Further, Patent Documents 8 and 9 each propose a connection method by threading a wire tip. In this method, as shown in FIG. 5, by forming the female screw portion 1a and the male screw portion 2a at the ends of the wires 1 and 2, the wires 1 and 2 are connected without using a machine such as a welding machine. It is. However, when one or both of the wires 1 and 2 are long, it is not easy to rotate the wires 1 and 2 for screwing. Therefore, in Patent Document 9, as shown in FIG. 6, a reverse thread portion 1 b is formed on one of the old wire 1 and the new wire 2 (for example, the old wire 1), and the connecting welding wire 3 is provided. A technique of simultaneously connecting the new wire 2 and the old wire 1 by rotating only the connecting welding wire 3 in one direction without rotating the wires 1 and 2 by forming the screw portion 3a and the reverse screw portion 3b. Is disclosed.

Japanese Utility Model Publication No. 42-10667 Japanese Utility Model Publication No. 43-23691 Japanese Utility Model Publication No. 42-10668 Japanese Examined Patent Publication No. 46-14522 Japanese Utility Model Publication No. 45-31735 JP-A-45-34250 Japanese Patent Laid-Open No. 54-23347 Japanese Utility Model Publication No. 49-157582. JP 59-27717 A

  As a result of examining the method of mechanically connecting old and new welding wires by the present inventors, as compared with the method of joining by butt welding, the occurrence of disconnection at the connecting portion and the current and voltage during welding become unstable. It has been found that the welding quality is likely to vary due to problems such as ease. With regard to these problems, the techniques disclosed in Patent Documents 1 to 6 do not mention the strength of the connecting portion, and it takes time to process the wire tip, resulting in a decrease in productivity. Seem. In patent document 7, the fitting part shape of a connection part is not shown clearly, and the intensity | strength of a connection part is not evaluated. Similarly, Patent Documents 8 and 9 neither evaluate nor suggest the strength of the connecting portion.

  In other words, the above-mentioned prior art discloses a method of connecting, but does not find any problems such as occurrence of disconnection at the connecting portion or unstable current and voltage during welding, and neither disclosure nor suggestion. .

  As a result of intensive studies, the present inventors have used connection welding wires having male screw portions on both end sides, and when connecting the first and second welding wires having female screw portions that mesh with the male screw portions. The connection welding wire has a diameter of 0.625 to 0.75 with respect to the diameters of the first and second welding wires, and each of the male screw processed portion and the male screw non-processed portion of the connection welding wire If the ratio of the length is 2: 1 to 3: 2 and the length of the male threaded portion of the connecting welding wire is 8 mm or more, the present invention is found to be able to solve the above problems. completed.

The present invention uses a connecting welding wire having a male threaded portion and an unprocessed portion in this order from the end face in the axial direction at both ends, and a first welding wire having a female threaded portion that meshes with the male threaded portion, and a second welding wire. When the welding wire is connected, the ratio of the diameter of the male thread portion of the connecting welding wire to the diameter of the first welding wire or the second welding wire is 0.625 to 0.75, the connecting welding wire the ratio of the external thread portion and the unprocessed portion each length in the axial direction 2: 1 to 3: 1 or 2, and the length of the external thread portion in the axial direction of the welding wire consolidation is not less than 8 mm, the The diameter of each welding wire, the second welding wire, and the connecting welding wire is 4.0 mm or 4.8 mm, and each of the first welding wire, the second welding wire, and the connecting welding wire is C : 0.12% by mass, Cu plating having a chemical composition having Si: 0.01% by mass, Mn: 1.93% by mass, P: 0.011% by mass, S: 0.005% by mass, and a thickness of 1.05 μm A welding wire connecting method characterized by having a coating .

  According to the present invention, for example, when welding a large-diameter steel pipe, welding can be performed without causing breakage during feeding of the welding wire and maintaining a stable current and voltage during welding. The loss of the end portion can be reduced, and even when the welding wire connecting portion is used, the welding quality can be kept stable and welding can be performed efficiently.

FIG. 1 is an explanatory view showing a connecting method of the present invention. FIG. 2 is an explanatory diagram showing wire bending and welding positions. FIG. 3 is an explanatory view showing a welding state when the welding wire is broken. FIG. 4 is an explanatory view showing a welding state of the welding wire of the present invention. FIG. 5 is an explanatory view showing a threaded connection method of welding wires. FIG. 6 is an explanatory diagram showing a method of connecting the new wire and the old wire.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory view showing a connecting method of the present invention. In FIG. 1, only the right half from the axial center of the connecting welding wire 4 is shown, and the left half is omitted.

  As shown in FIG. 1, in the present invention, a first welding wire (for example, an old wire) 5 and a second welding wire (for example, a new wire) are coupled using a coupling welding wire 4. In FIG. 1, the second welding wire is omitted.

A male screw portion 6 and an unprocessed portion 7 are formed in this order from both end portions of the connecting welding wire 4 in the axial direction.
Moreover, the internal thread part 8 is formed in the edge part of the 1st welding wire 5 and the 2nd welding wire. The female screw portion 8 meshes with the male screw portion 6.

  The female thread portion 8 of one of the first welding wire 5 and the second welding wire (for example, the first welding wire 5) is formed as a reverse thread portion, and at both ends of the connection welding wire 4. One male screw portion 8 of the screw portions is also formed as a reverse screw portion. Thus, the first welding wire 5 and the second welding wire are simultaneously rotated by rotating only the connecting welding wire 4 in one direction without rotating the first welding wire 5 and the second welding wire. Can be linked.

The diameter of the first welding wire 5 and the diameter of the second welding wire are usually the same value.
Here, the ratio of the diameter of the welding wire 4 for connection to the diameter of the first welding wire 5 or the second welding wire is 0.625 to 0.75. If this ratio is less than 0.625, when a bending force is applied during feeding of the welding wire, there is a risk of breaking at the male threaded portions 7 and 8, while if the ratio is more than 0.75, Breakage occurs at the female screw portion 6. If the ratio is less than 0.625, the deformation concentrates on the root portion of the male screw, and if the ratio exceeds 0.75, the male screw will break through the female screw.

  Moreover, the ratio of each length of the external thread part 6 and the non-processed part 7 regarding the axial direction of the welding wire 4 for connection is 2: 1-3: 2. When the ratio is out of this range, the welding wire may be broken during feeding, and the current and voltage during welding may not be stably maintained.

  Furthermore, the length of the external thread portion 6 in the axial direction of the welding wire 4 for connection is 8 mm or more. If this length is less than 8 mm, the current and voltage during welding may not be stably maintained.

  According to the present invention, for example, when welding a large-diameter steel pipe, the welding wire can be welded without breaking at the time of feeding and stably maintaining the current and voltage at the time of welding. In this case, welding can be performed while maintaining stable welding quality, loss at the end of the welding wire can be reduced, and welding can be performed more efficiently.

  The present invention will be described more specifically with reference to examples.

FIG. 2 is an explanatory view schematically showing the vicinity of the welded portion 10 of the submerged arc welding machine 9 actually used.
When manufacturing a large-diameter steel pipe, the wire 11 is bent and fed in the vicinity of the welded portion 10 so that welding in a narrow space is possible. The bending method of the wire 11 is three-point bending (bending R100 mm) using the roller 12.

Therefore, tensile strength: 540 N / mm ² or more, chemical component: C: 0.12 mass%, Si: 0.01 mass%, Mn: 1.93 mass%, P: 0.011 mass%, S: 0.00. The bending resistance performance required at the time of continuous supply was evaluated under various screw machining conditions shown in Table 1 using 4.0 mm and 4.8 mm diameter wires each consisting of 005 mass% and Cu plating thickness: 1.05 μm. Table 1 shows the strength and bending characteristics of the prototype wire.

  FIG. 3 is a graph showing an example of current and voltage conditions that occur during welding when the wire connecting portion is broken. When passing through the fracture during welding, as shown in the graph of FIG. 3, the arc is instantaneously short-circuited and re-pointed, so both the current and voltage become unstable.

  FIG. 4 is a graph showing an example of current and voltage conditions during welding when the connecting portion does not break. If the wire does not break, welding is possible while maintaining both current and voltage stability.

  As a result, at a wire diameter of 4.0 mm, the screw diameter / wire diameter ratio is 0.5 (prototype 1), the screw diameter / wire diameter ratio is 0.75, and the unmachined to screw ratio is 1: 1. In the case (prototype 3), judgment occurred in the 100R bending test.

On the other hand, no breakage occurred under the conditions of prototypes 2 and 4.
Next, as a result of performing welding under the conditions shown in Table 2 for the prototypes 2 and 4 and investigating the influence of the screw shape on the welding conditions, in the prototype 2, the current and voltage were unstable.

In the present invention (prototype 4), it was confirmed that the current and voltage were kept stable at the connecting portion and welding was possible.
Similarly, the same result was obtained for the 4.8 mm diameter wire under the conditions of the trial production 7.

DESCRIPTION OF SYMBOLS 1, 2 Wire 1a Female thread part 2a Male thread part 1b Reverse thread part 3 Connection welding wire 3a Screw part 3b Reverse thread part 4 Connection welding wire 5 1st welding wire (For example, old wire)
6 Male thread 6
7 Unprocessed part 8 Female thread part 9 Submerged arc welding machine 10 Welded part 11 Wire 12 Roller

Claims (1)

A first welding wire and a second welding wire each having a female threaded portion that meshes with the male threaded portion at both ends using a connecting welding wire having a male threaded portion and an unprocessed portion in this order from the end face toward the axial direction. , The ratio of the diameter of the male thread portion of the connecting welding wire to the diameter of the first welding wire or the second welding wire is 0.625 to 0.75, the connecting welding wherein the axial direction of the wire externally threaded portion and the ratio of the unprocessed portion each length 2: 1 to 3: 1 or 2, and the length of the male screw portion for the previous SL-axis direction is greater than or equal to 8 mm, the The diameter of each of the first welding wire, the second welding wire, and the connection welding wire is 4.0 mm or 4.8 mm, the first welding wire, the second welding wire, and the connection Welding wai Each has a chemical composition having C: 0.12 mass%, Si: 0.01 mass%, Mn: 1.93 mass%, P: 0.011 mass%, S: 0.005 mass%, And a welding wire connecting method comprising a Cu plating film having a thickness of 1.05 μm .

Images