JP2014018824A - Butt welding method for steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a butt connection method for a steel plate, which can sufficiently achieve the simplification and cost reduction of preworking and which can reliably achieve high-efficiency and high-strength butt weld joint.SOLUTION: In a butt welding method for a steel plate, a plurality of protrusions 3 are preformed at each predetermined interval S on an end surface 2a of one of two steel plates 1 and 2, and welding is performed in the state of making the protrusions butt against an end surface 1a of the other steel plate. Preferably, each of the protrusions has the same thickness as that of the steel plate, and assumes a trapezoidal shape or a rectangular shape in a plan view.

Description

  The present invention relates to a butt welding method for steel plates in which end faces of two steel plates are butted to perform welding.

  Conventionally, as a butt welding method of such steel plates, for example, as shown in FIG. 8, at least one of the end portions of two steel plates 101 and 102 is previously welded with a large inclination angle (also simply referred to as “groove”). The processing of 103 is performed over the entire length, and a backing metal 104 is arranged on the back surface side, and welding is performed so that molten metal (not shown) is melted into the welding groove 103 from the front surface side. It has been known. Note that the backing metal 104 is omitted when there is no risk of the molten metal falling off.

  As another butt welding method, as shown in FIG. 9, two steel plates 111 and 112 are placed with a predetermined gap, that is, a root gap (also simply referred to as “gap”) R, between their end faces. It is also known that welding is performed so that molten metal (not shown) is melted into the root gap R from the front surface side after the backing metal 114 is disposed on the back surface side.

  However, among the above-described conventional butt welding methods, it is not easy to perform beveling with an accurate inclination over the entire length of the end portions of the steel plates 101 and 102 in the former method. In addition, it is difficult to ensure the penetration depth of the molten metal into the weld groove 103, and multi-pass welding is required to fill the leg length. In order to reduce the number of passes, it is necessary to increase the welding heat input such as reducing the welding speed or increasing the welding current, but there is a problem that the welding heat deformation and the strength decrease become remarkable.

  On the other hand, the latter has the advantage that the molten metal is deeply melted into the route gap R and the number of passes can be reduced, but in order to secure the route gap R, a backing metal 114 is used. It is necessary to perform gap adjustment temporary attachment or to arrange a spacer between the end surfaces of the two steel plates 111 and 112. For this reason, there is a problem that pre-processing is troublesome and the cost is increased due to an increase in the number of parts.

  Therefore, instead of the conventional butt welding method, there is a demand for a new butt welding method in which pre-processing can be performed easily and at low cost, and the number of passes is small and high efficiency and high strength can be obtained. As an answer to this demand, for example, as disclosed in Patent Document 1, an uneven surface is formed on the end surface of at least one of the two steel plates, and the uneven surface is brought into contact with the other steel plate. There have been proposed welding methods for joints that are welded together.

Japanese Patent Laid-Open No. 9-262689

  However, in the above proposed welding method, it is necessary to continuously form an uneven surface on the end face of the steel sheet over the entire length as a joint pre-processing, and therefore it is not possible to sufficiently simplify and reduce the cost of the pre-processing. . In addition, because the projections on the uneven surface are in contact with the other steel plate in a state where they are close to each other, it is difficult to weld the molten metal without falling off, and a high-efficiency and high-strength butt-welded joint is obtained. Not enough.

  The present invention has been made in view of the above points, and the problem is that the proposed welding method is improved so as to be suitable for a butt-welded joint, thereby sufficiently simplifying and reducing the cost of pre-processing. It is an object of the present invention to provide a method for butt-connecting steel sheets that can achieve a high-efficiency and high-strength butt-welded joint.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a method of butt welding of steel plates in which the end surfaces of two steel plates are butted against each other, and a plurality of the end surfaces of one of the two steel plates are previously provided on one end surface of the two steel plates. These projections are formed at predetermined intervals, and welding is performed in a state where these projections are abutted against the end face of the other steel plate.

  In this configuration, since only a plurality of protrusions are formed at predetermined intervals on the end face of one steel plate as a pre-processing of the butt weld joint, compared with the case where a conventional welding groove or uneven surface is continuously formed. Pre-processing can be easily performed at low cost. In addition, the height of the projection is also cut after the pre-processing, and the gap between the end surfaces of the two steel plates, that is, the root gap, in a state where the projection is abutted against the end surface of the other steel plate, that is, the root gap is relatively easily adjusted. In addition, since the molten metal is deeply penetrated into the root gap and the number of passes is reduced, a highly efficient and high strength butt weld joint can be realized.

  The invention according to claim 2 is the steel plate butt welding method according to claim 1, wherein each of the protrusions has the same thickness as that of the steel plate and has a trapezoidal or rectangular shape when seen in a plan view. . In this configuration, it is possible to improve the assembly stability of both steel plates in a state where the projections are in contact with the end surface of the other steel plate while simplifying the forming process of the projections as a pre-processing, so that butt welding is performed. High efficiency and high strength of the joint can be achieved.

  According to a third aspect of the present invention, in the butt welding method for steel sheets according to the second aspect, the specific size of each of the protrusions is specified. That is, each of the protrusions is configured such that the protrusion height is set to 1.5 to 5 mm, and the protrusion proximal end width dimension is set to be greater than the protrusion height and equal to or less than 15 mm.

  According to a fourth aspect of the present invention, in the butt welding method for steel sheets according to the second or third aspect, the interval between two adjacent protrusions is set at an equal interval of 50 to 300 mm. In this configuration, since the interval between two adjacent protrusions is equal, the forming process of the protrusion as the pre-processing can be simplified accordingly.

  According to a fifth aspect of the present invention, in the butt welding method for steel sheets according to any one of the second to fourth aspects, when the thicknesses of the two steel sheets are different from each other, the protrusions are formed with the smaller thicknesses. It is set as the structure formed in the end surface of this steel plate. In this configuration, each projection is formed on the end face of the steel plate having the smaller thickness, and the thickness of each projection is small accordingly, so that each projection is quickly melted by welding heat, and the welding efficiency is increased accordingly. Get higher.

  According to a sixth aspect of the present invention, in the butt welding method for steel sheets according to any one of the second to fourth aspects, when the thicknesses of the two steel sheets are different from each other, the protrusions are formed on the larger thickness side. It is set as the structure formed in the end surface of this steel plate. In this configuration, each protrusion can be scraped to an inclined surface with no step during assembly / adjustment after pre-processing, and the step can be reduced by welding along the inclined surface of each protrusion during butt welding. No butt weld joint can be realized relatively easily.

  As described above, according to the butt welding method of the steel sheet according to the present invention, a plurality of protrusions are merely formed at predetermined intervals on the end surface of one steel sheet as a pre-processing of the butt weld joint. Compared to the case where the tip and the uneven surface are continuously formed, the pre-processing can be performed easily and at low cost. In addition, the height of the projection and the root gap between the two steel plate end faces can be adjusted relatively easily after the pre-processing, and the molten metal is deeply penetrated into the root gap. Therefore, a high-efficiency and high-strength butt-welded joint can be reliably realized.

  In particular, in the invention according to claim 2, it is possible to improve the assembly stability of both steel plates in a state in which the protrusion is in contact with the end surface of the other steel sheet while simplifying the forming process of the protrusion as the pre-processing. Therefore, high efficiency and high strength of the butt weld joint can be achieved more reliably.

  Moreover, in the invention which concerns on Claim 5, when the thickness of two steel plates differs, each projection part is formed in the end surface of the steel plate with the smaller thickness, and since the thickness of each projection part is small correspondingly, Melting by welding heat can be performed quickly, and the welding efficiency can be increased accordingly.

  Furthermore, in the invention according to claim 6, when the thicknesses of the two steel plates are different, each projection is formed on the end surface of the steel plate having the larger thickness. A sloped surface with no step can be formed by shaving, and a butt weld joint without a step can be realized relatively easily by performing welding along the inclined surface of each projection during butt welding. This is particularly effective when the difference in thickness between the two steel plates is large.

FIG. 1 is a plan view showing a state of an assembly stage of a butt welding method for steel sheets according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of X in FIG. FIG. 3 is an enlarged cross-sectional view taken along line YY of FIG. FIG. 4 is an enlarged cross-sectional view taken along line ZZ in FIG. FIG. 5 is a view showing the shape of the protrusion for explaining the butt welding method for steel sheets according to the embodiment of the present invention. FIG. 6 is a diagram showing two types of electrode wirings. FIG. 7 is an explanatory diagram for explaining an example of hybrid laser welding. FIG. 8 is a cross-sectional view for explaining a conventional butt welding method. FIG. 9 is a cross-sectional view for explaining another conventional butt welding method.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments that are modes for carrying out the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 4, when two steel plates 1 and 2 are brought into contact with each other and welded, a plurality of protrusions 3 are formed on the end surface 2 a of one steel plate 2 of the two steel plates 1 and 2 in advance. , 3,... Are formed at predetermined intervals S. Then, these projecting portions 3, 3,... Are abutted against the end surface 1a of the other steel plate 1, and the backing metal 4 is arranged along the abutting surface on the back surface side of the steel plates 1, 2 for assembly. After this assembly, welding is performed along the butt surfaces of the steel plates 1 and 2. As this welding method, a MAG welding method, a submerged arc welding method, a so-called hybrid laser welding method, or the like is used.

  According to such a butt welding method for the steel plates 1 and 2, as a pre-processing of the butt weld joint, only a plurality of protrusions 3, 3,... Are formed on the end surface 2a of one steel plate 2 at predetermined intervals S. Therefore, the pre-processing can be easily performed at a low cost as compared with the case where the conventional welding groove 103 (see FIG. 8) and the uneven surface are continuously formed.

  Further, by cutting the protrusion 3 after pre-processing, the height of the protrusion 3 and thus the gap between the end faces 1a, 2a of the two steel plates 1, 2 in a state where the protrusion 3 is abutted against the end face 1a of the other steel plate 1, that is, Since the root gap R can be adjusted relatively easily, and the molten metal is deeply penetrated into the root gap R and the number of passes is reduced, a highly efficient and high strength butt weld joint can be realized.

  Here, each of the protrusions 3 has the same thickness as the steel plates 1 and 2 and has a rectangular shape in which the protrusion distal end side width dimension B1 is equal to the protrusion proximal end width dimension B2 as shown in FIG. It is preferable that the protrusion has a trapezoidal shape in which the protrusion distal end side width dimension B1 is smaller than the protrusion proximal end side width dimension B2. In this case, the forming process of the protrusion 3 as the pre-processing can be performed together with the cutting process of the steel plate 2, and the pre-processing can be further simplified and reduced in cost. In addition, since the assembly stability of both the steel plates 1 and 2 in a state in which each projection 3 is abutted against the end surface 1a of the other steel plate 1, it is possible to increase the efficiency and strength of the butt weld joint. be able to.

  In addition, each of the protrusions 3 is preferably set to have a protrusion height H of 1.5 to 5 mm and a protrusion base end side width dimension B2 larger than the protrusion height H and 15 mm or less. From the viewpoint of welding efficiency (speed, amount of heat input, number of passes), it is better that the projection height H of the projection 3 is small and the root gap R is narrow, but in the case of arc welding, the bottom from the wire diameter (1.2 mm) In consideration of the penetration up to the above, the lower limit of the protrusion height H is 1.5 mm. The protrusion base end side width dimension B2 of the protrusion 3 needs to be larger than the protrusion height H so as not to cause breakage or the like when the protrusion 3 is cut for adjusting the root gap R. When it becomes large, the undissolved part of the projection part 3 and unwelding will occur.

  Furthermore, it is preferable that the space | interval S between the adjacent two protrusion parts 3 and 3 is set to 50-300 mm at equal intervals. If the spacing S is equal, the forming process of the projections 3 as the pre-processing becomes that much simpler, and the pre-processing can be further simplified and reduced in cost. The interval S is preferably as large as possible in order to reduce the total number of the protrusions 3 and simplify the molding process, but the upper limit is set to 300 mm in consideration of the temporary attachment pitch during assembly.

  As for the temporary attachment interval at the time of assembly, it is preferable to provide the projection 3 at or near the projection 3 with the same pitch as the projection 3. However, if the distortion caused by the welding has an adverse effect, the two adjacent projections 3, 3 are used. Temporary welding from the backing metal 4 side may also be performed between the two. The tack welding width is set to about 15 mm, which is the same as the base end side width dimension B2 of the protrusion 3, so that a poorly formed shape is not formed on the surface of the torch side because poor penetration occurs.

  In the said embodiment, although the thickness of the two steel plates 1 and 2 was the same, when the thickness of two steel plates differs, each said projection part 3 is good to form in the end surface of the steel plate with a smaller thickness. In this case, each projection 3 is formed on the end face of the steel plate having the smaller thickness, and the thickness of each projection 3 is reduced accordingly, so that the fusion of each projection 3 by welding heat is performed quickly, and accordingly The welding efficiency can be increased. Conversely, each of the protrusions 3 may be formed on the end surface of the thicker steel plate. In this case, each protrusion 3 can be scraped into an inclined surface having no step at the time of assembly / adjustment after pre-processing, and the step can be made by welding along the inclined surface of each protrusion 3 at the time of butt welding. A butt-welded joint without a gap can be realized relatively easily.

  Next, as a butt welding method, Example 1 using a mag welding method, Example 2 using a submerged arc welding method, and Example 3 using a hybrid laser welding method will be described.

Mag welding is widely used for butt welding of steel plates. The welding apparatus is YD-350GE2 (manufactured by Panasonic), the torch angle is vertical, the wire protruding length is 15 mm, the shielding gas is Ar + 20% CO ₂ , the flow rate is 25 L / min, and the welding material is MGS-80 (φ1.2 mm).

  In this mag welding method, as shown in Table 1 below, the thicknesses of the steel plates 1 and 2 are 6 mm and 9 mm, the projection height H of the projection 3 and the root gap R is 3 mm and 5 mm, and two adjacent two The test was carried out for each of the cases where the spacing (projection spacing) S between the projections 3 and 3 was 50 mm, 150 mm and 300 mm. In Examples 1 to 3, as shown in FIG. 5, the protrusion 3 has a protrusion tip-side width dimension B1 of 2 mm regardless of the protrusion height H, as viewed in a plan view. Both sides have a trapezoidal shape inclined at 45 °.

For comparison with Example 1, Table 2 below shows welding conditions in which butt welding was performed in the case of a plate thickness of 6 mm provided with a conventional V-shaped groove using the same mag welding method.

Table 3 below shows welding conditions in which butt welding was performed in the case of a plate thickness of 9 mm provided with a conventional V-shaped groove using the mag welding method.

  When comparing Example 1 shown in Table 1 above and the conventional examples shown in Tables 2 and 3, the plate thickness is set even though the welding conditions (welding speed, current and voltage of the mag output) are substantially the same. It can be seen that in both cases of 6 mm and 9 mm, the number of passes in Example 1 is smaller than that in the conventional example.

  The submerged arc welding method is a large current welding using a flux, and the welding deformation is large, but it is widely used for butt welding of steel plates like the mag welding method, so the applicability of this method was examined.

The welding power source is Power Wave AC / DC 1000 manufactured by Lincoln Electric, the flux is PFH-55E, 10 × 48 mesh or MF-38, 12 × 65 mesh, the plate thickness is 6-9 mm, and the gap (root gap R) is 3. ˜4 mm, the welding wire is US-36, φ4.0 mm. Since submerged arc welding requires a flux assembling in the groove in advance, workability was taken into consideration, and the performance was compared between 1-pass tandem and single electrode as shown in FIG. All the protrusion intervals S are 150 mm, but since the heat distortion increases due to the amount of heat input, tack welding was performed at intervals of 50 mm.
(1) When the flux is PFH-55E and 10 × 48 mesh, the welding test results are shown in Table 4 below.

All the test pieces in Table 4 have a plate thickness of 6 mm. 1M / min welding in tandem and 0.7M / min welding in single are possible, respectively, and one-pass welding under the same conditions is possible regardless of the groove. In Table 4, a groove column with I corresponds to an example, and a V60 ° column corresponds to a conventional example of a V-shaped groove. Further, L / T in the current / voltage column means a leading electrode / following electrode.
(2) When the flux is MF-38, 12 × 65 mesh, the welding test results are shown in Table 5 below.

The test pieces of Table 5 have plate thicknesses of 6 mm and 9 mm. If Table 4 is taken into consideration, one-pass welding can be performed under the same conditions regardless of the flux and groove. However, since the heat input is large, the thermal strain is quite large.
The welding conditions in the example of the I-shaped groove are summarized in Table 6 below.

  From the above, the present invention can also be applied to the case where butt welding of the steel plates 1 and 2 is performed using the submerged arc welding method, and a high-efficiency and high-strength butt-welded joint is obtained by reducing the number of passes. There are effects such as realization.

  As shown in FIG. 7, the hybrid laser welding method uses high energy laser irradiation that generates a keyhole for arc melting such as mag welding, and is suitable for narrow gap welding with a gap of 1 mm or less. Is. The applicability of this welding method was examined.

Mag welding device is DW300 (Daihen), DC pulse, shielding gas is Ar + 20% CO ₂ , flow rate is 25 L / min, laser device is fiber laser YLR-10000 (IPG maximum output: 10 kW), laser torch angle 90 ° (Perpendicular to the welding surface), a mag torch angle of 60 °, and a distance between the laser and the mag of 0.6 mm.

  In this hybrid laser welding method, as shown in Table 7 below, the thicknesses of the steel plates 1 and 2 are 3.2 mm, 6 mm, and 9 mm, the projection height H of the projection 3 and the gap R is 1.5 mm. And 2 mm and 3 mm or 5 mm, and the projection spacing S was 50 mm, 150 mm and 300 mm, respectively.

  Table 7 shows the results of a welding test in which thermal distortion is small and tack welding is not required (the shape can be maintained only by the protrusion 3) in consideration of the following. That is, when the gap is large, the welding speed is reduced. Multipass welding is also possible. Decreasing the welding speed and increasing the mag-current value increase the amount of thermal deformation as the heat input increases. Therefore, when increasing the protrusion spacing S, it was determined that it would be better to reduce the mag current value and perform multi-pass welding.

  As can be seen from the welding test results, the present invention can also be applied to butt welding of the steel plates 1 and 2 using the hybrid laser welding method, particularly when the gap is small. It is effective to implement the present invention using a laser welding method.

1, 2 Steel plates 1a, 2a End face 3 Protrusion 4 Backing metal S Predetermined distance R Route gap H Protrusion height B1 Protrusion tip side width dimension B2 Protrusion base end side width dimension

Claims (6)

In the butt welding method for steel plates, in which the end faces of two steel plates are butted together and welded,
A plurality of protrusions are formed on the end surface of one of the two steel plates in advance at predetermined intervals, and welding is performed in a state where these protrusions are in contact with the end surface of the other steel plate. A butt welding method for steel sheets.   2. The steel plate butt welding method according to claim 1, wherein each of the protrusions has the same thickness as the steel plate and has a trapezoidal shape or a rectangular shape when seen in a plan view.   3. The steel sheet butt welding method according to claim 2, wherein each of the protrusions has a protrusion height of 1.5 to 5 mm and a protrusion proximal side width dimension set to be larger than the protrusion height and 15 mm or less.   The butt welding method for steel sheets according to claim 2 or 3, wherein the interval between two adjacent protrusions is set at an equal interval of 50 to 300 mm.   5. The steel sheet butt welding method according to claim 2, wherein when the two steel plates have different thicknesses, the protrusions are formed on an end surface of the steel plate having a smaller thickness.   5. The steel sheet butt welding method according to claim 2, wherein, when the two steel plates have different thicknesses, the protrusions are formed on an end surface of the steel plate having a larger thickness.