JPH0698487B2 - Joining method for band steel for ERW pipe - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for welding a trailing edge of a leading strip and a leading edge of a trailing strip sent from an uncoiler in an electric resistance welded pipe manufacturing mill line.

Conventional technology ERW pipe manufacturing mill line is generally as shown in FIG.
The strip steel (11) wound into a coil by hot or cold rolling is unwound by the uncoiler (12) and flattened by the leveler (13) in the entry process, and then the leading edge and the last. The defective part at the end is cut off by the end cut shear (14). Then, in the end welder (15), the trailing edge of the leading strip and the leading edge of the trailing strip are butted and welded. During that time, the looper (16) supplies the accumulated strip steel to the pipe making machine (17) after the forming process, and absorbs the time required for the butt welding of the trailing edge of the preceding strip and the leading edge of the following strip. , To ensure continuity of the subsequent pipe manufacturing process. However, recently, there are mills with a pipe making speed of over 150 m / min, and the welding time of the strip steel in the end welder is
It is important in determining mill performance.

The above conventional continuous pipes are mainly used for medium diameters of 200 mm or less.
It was carried out in a small diameter mill.

However, recently, continuous pipe production is being applied to large-diameter mills for the purpose of improving efficiency and improving product yield by reducing defective portions of the coil front end and rear end.

In continuous pipe making in a large diameter mill, the width of the strip steel welded by the end welder becomes wide and the thickness becomes thick. For this reason, the time required for welding becomes long, and the looper for supplying the strip steel to the pipe manufacturing process must be large in the meantime.

Therefore, the conditions that the end welder in continuous pipe manufacturing in a large diameter mill should have are: (1) a looper and subsequent forming step, sufficient welding strength that does not break in the constant diameter step, and (2) narrow width It is required to be able to weld various strip steels from wide to wide and thin to thick (3) Welding in a short time.

All of this applies to small diameter mills,
For large diameter mills, there is a more urgent need.

The reason is that the larger the diameter, the greater the required welding strength, and the larger the diameter, the greater the difference between the maximum and minimum width and thickness. This is because a shorter length does not limit the ability of the pipe manufacturing process, and a small looper may be used, which can significantly reduce the equipment cost.

As a method of shortening the welding time in the above-mentioned end welder, a method of welding by high current MIG welding (JP-A-57-142776) or a method of performing by gas shielded arc welding having a plurality of consumable electrodes is proposed. Has been done.

The problem to be solved by the invention Even if the method of welding by the large current MIG welding of JP-A-57-142776 is applied, for a strip steel having a wall thickness of 6 mm to 19.1 mm, a practically feasible welding speed is It is 600 to 1200 mm / min, and if a plate width of 2000 mm is to be welded, it will take 3.3 to 1.7 minutes, and the required time is by no means a short time.
It is insufficiently efficient.

Further, it is clear that the method of performing gas shielded arc welding having a plurality of consumable electrodes can shorten the welding length per each electrode and the welding time. However, it is difficult to deal with the width variation of the strip steel from a narrow width to a wide width simply by arranging a plurality of electrodes, and even if it is put into practical use, its control method and electrode running equipment are not large-scale. I have no choice.

An object of the present invention is to efficiently weld various strip steels from narrow width to wide width, thin plate to thick plate with relative ease in a gas shielded arc welding apparatus using a plurality of welding torches as end welders for the strip steel. The present invention provides a method of joining strip steels for electric resistance welded pipes.

Means for Solving the Problems In order to achieve the above-mentioned object, various tests were conducted to apply gas shielded arc welding using a plurality of welding torches to a welding apparatus for band steel for ERW pipes. As a result, a plurality of welding torches are divided into two sets and mounted on traveling carriages at predetermined intervals, one traveling carriage being at one side end of the strip steel and the other traveling carriage at the other side end of the strip steel. By arranging and welding from both ends of the strip toward the center, it was clarified that various strips from narrow width to wide width, thin plate to thick plate can be efficiently welded relatively easily. Arrived

That is, the present invention is a method for joining a leading edge of a trailing strip steel fed from an uncoiler to a trailing edge of a preceding strip steel by a gas shield arc welding device having a plurality of welding torches in a ERW pipe manufacturing mill line. , Welding torches are divided into two sets and are arranged at predetermined intervals on the traveling carriage respectively, and the number of welding torches to be used is selected according to the width of the band steel to be joined,
Welding is performed from both end faces of the steel strip toward the center.

Effect In the present invention, in a method of joining by a gas shielded arc welding apparatus having a plurality of welding torches, the welding torches are divided into two sets, and the welding torches are respectively arranged at predetermined intervals on the traveling carriage, depending on the width of the strip steel. , The number of welding torches to be used is selected, and welding is performed from the both end faces of the steel strip toward the center.

Therefore, if the strip steel width to be welded is W, the distance between the welding torches arranged on each traveling carriage is L, and the closest approaching distance resulting from the equipment restriction of the tip welding torch of each traveling carriage is A,
The number of welding torches to be used and the length to be welded by each welding torch are determined so that the required welding time is the shortest in accordance with the L, A and the strip steel width W given in terms of equipment.

Various methods can be considered for determining the number of welding torches to be used and the length to be welded by each welding torch, as described later. However, the maximum welding length of one welding torch is L + A, and if the optimum welding speed determined by the plate thickness, welding conditions, etc. is V, the required welding time T is T = (L
+ A) / V enables welding over the entire width.

In this invention, the start position of the welding torch is set to the both ends of the steel strip, but this is (1) if the soundness of the welding start point and the welding end point are compared,
At the welding end point, an incomplete welding part generally called a crater remains, resulting in inferior soundness compared to the welding start point. (2) Unevenness in the width direction of the load of the welding part caused by the strip steel The uneven load on the weld that occurs during the strip forming process is
This is because the edge is required to be larger and sounder. As a result, it becomes possible to perform welding with an inexpensive device without adding a crater processing function to the welding device.

The number n of welding torches to be installed and the welding torch interval L are
From the width range of the band steel to be welded and the allowable welding time T,
It is determined arbitrarily.

When the welding torch is divided into two sets, one traveling torch can be equipped with one welding torch, the other traveling torch can be equipped with the remaining welding torches, and both traveling vehicles can be equipped with half of them. You can also When the number of welding torches to be installed is large, it is advantageous to equip both traveling carriages with half the load, but there is no advantage in terms of shortening the welding time.

EXAMPLE The method of the present invention will be described in detail with reference to FIGS. 1 and 2 showing a welding apparatus used in the method of the present invention.

A leading strip steel (1) whose rear end is cut by an unillustrated end cut shear and a trailing strip steel (2) whose tip is similarly cut by an uncut end shear are Edge (1a) and leading edge (2a) of trailing strip steel (2)
Are butted and clamped on a clamp device (not shown), and then n welding torches (3-1) to (3-n)
Welded by gas shielded arc welding with consumable electrode wire (4) fed to.

These welding torches (3-1) to (3-n) have a welding torch (3-1) on one traveling carriage (5) and a welding torch (3-2) to (3) on the other traveling carriage (6). 3-n) are mounted at a predetermined interval L. The traveling carriages (5) and (6) are arranged at both ends of the steel strip.

Let W be the width of the steel strip to be welded, and let A, which is not shown, be the closest distance that can be caused by the facility restrictions of the welding torch (3-1) and the welding torch (3-2).

After arranging the welding torches in this way, the number of welding torches to be used and the welding of each welding torch are made so that the required welding time is the shortest according to L, A and the strip steel width W to be joined given to the equipment. Determine the length to be welded and weld from both ends.

Various methods can be considered for determining the number of welding torches to be used and the length of each welding torch to be welded.

For example (1) In the case of W ≧ 2L + A Select the welding torch (3-1) and the welding torch (3-2), and from the one end to the (WA) / 2 welding torch (3-1) by the traveling carriage (5). ), The traveling carriage (6) is used to weld (W + A) / 2 from the other end with the welding torch (3-2).

(2) In the case of 2L + A <W ≦ 3L + A Select the welding torches (3-1) to (3-3), and arrange the welding torch (3-1) at one end and the welding torch (3-3) at the other end. Welding torch (3-1) for W- (2L + A), welding torch (3-2) for L + A, welding torch (3-3)
Weld L with.

(3) In the case of NL + A <W ≦ (N + 1) L + A Welding torches (3-1) to (3-n + 1) are selected, and the welding torch (3-1) is at one end, and the welding torch (3-n + 1).
Is placed at the other end, and the welding torch (3-1) is used for W- (NL +
A) is welded to L + A with a welding torch (3-2), and L is welded to with other welding torches (3-3) to (3-n + 1).

By determining in this way, the maximum welding length in one welding torch is L + A for strips of all widths, and if the optimum welding speed determined by the plate thickness, welding conditions, etc. is V, the required welding time is T can be welded over the entire width by T = (L + A) / V regardless of the strip steel width.

Next, FIG. 2 shows an example of a method of measuring the strip steel width W to be welded. In such an end welder, the preceding strip steel (1)
Proper centering of the trailing edge and the leading edge of the trailing strip steel (2) is essential. This centering device (7a)
The movement amount of the guide rolls (8) to (7d) is calculated, the respective strip steel widths are calculated, and the required strip steel width W to be welded is measured. Further, the width of the steel strips (1) and (2) can be measured by another optical measuring device or a mechanical measuring device.

Example 1 By the arrangement of the welding torches described in FIG. 1 and FIG. 2, the number of welding torches is 6, the distance L between welding torches is 320 mm, and the welding torches (3-1) and (3-2) are closest to each other. Interval A: 100 mm
Welding equipment is used for high current MIG as a consumable electrode wire.
Welding 4.0 mmφ was used to weld a strip steel having a minimum width to a maximum of 2020 mm according to the welding method described with reference to FIGS. 1 and 2 by selecting the number of welding torches according to the strip width.

As a result, when the plate thickness was 19.0 mm, the welding speed was 500 mm / min and the maximum welding time was 50 seconds. When the plate thickness was 3.0 mm, the welding speed was 1800 mm / min and the welding time was 14 seconds at maximum, and welding was possible over the entire width.

As described above, according to the present invention, the gas shielded arc welding apparatus having a plurality of welding torches is used to weld the trailing edge of the leading strip steel and the leading edge of the trailing strip steel of the ERW pipe manufacturing mill line. It can be used as a welding device, the welding time can be shortened, and it can be applied to a large-diameter ERW pipe manufacturing mill line. Therefore, with a small capacity looper, it becomes possible to supply the strip steel to the pipe making machine without impairing the pipe making speed capability of the original pipe making machine, and the effect is great.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a welding apparatus used in the present invention, FIG. 2 is a schematic explanatory view of a strip steel width measuring method, and FIG. 3 is an explanatory view of a general ERW pipe manufacturing mill line. 1 ... Leading strip steel, 1a ... Trailing edge, 2 ... Trailing strip steel, 2a ... Tip edge, 3-1 to 3-n ... Welding torch, 4 ... Consumable electrode wire, 5, 6 ...... Trucking vehicle, 7a-7b …… Centering device, 8 …… Guide roll,

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B23K 9/173 E 7920-4E

Claims (1)

[Claims] 1. A method for joining a trailing edge of a preceding strip steel and a leading edge of a trailing strip steel sent from an uncoiler with a gas shielded arc welding device having a plurality of welding torches in a mill line for producing electric resistance welded pipes. , Welding torches are divided into two sets and are arranged on the traveling trolley at predetermined intervals respectively. The number of welding torches to be used is selected according to the width of the steel strips to be joined, and welding is performed from both end faces of the steel strips toward the center. A method for joining band steel for ERW pipe, which is characterized by the following.