JPH0243584B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for connecting metal strips in a continuous metal strip processing line. Most of the processing steps for metal strips, which are raw materials for products such as cold-rolled steel plates and cold-rolled steel strips made of ordinary steel, special steel, or other metals, are carried out on continuous processing lines. These processing lines perform pickling, rolling, cleaning, annealing, tempering, etc. The metal strip processed in each processing line is wound into a coil and called a coil for ease of handling. Therefore, the coil supplied to the processing line joins the rear end of the preceding coil and the front end of the following coil to enable continuous processing in the processing line. This metal strip connection method is mainly performed by welding, and the welding method is adopted in consideration of the material and thickness of the metal strip, processing details of the processing line, processing speed, etc. Among these welding joining methods, the present invention is suitable for rolling lines, etc., where the joint requires strength and small thickness error, and is particularly suitable for use with materials such as stainless steel, which is highly work hardened and has high tension during rolling. The purpose is to provide a welding method suitable for metal strips that require. As conventional welding methods, for example, flat butt welding is used for thick plates, and narrow seam welding is used for thin plates. Although they are used in different ways in this manner, in flash butt welding of thick materials, the entire width of the plate is electrically welded at the same time, so the welding strength in the width direction of the welded metal strip is not constant. This is because there are many factors that change the welding conditions in the width direction, such as changes in plate thickness, the quality of the shearing condition of the plate, and non-uniformity of the clamping device. For this reason, not only does the overall welding strength become low, but if there is a localized welding defect, stress is concentrated on that welding defect, making it even more likely to break. Breakage of welded parts of metal strips during continuous processing such as rolling causes large downtime losses required for accident treatment, and preventing breakage not only improves safety, work efficiency, and productivity, but also prevents roll damage and It becomes possible to reduce high costs due to quality abnormalities, etc., and the effect is extremely large. Next, a method of welding a metal strip joint by conventional narrow tup seam welding will be described. In Fig. 1, 1 is a preceding metal strip having a thickness Tc, which is a preceding coil passing through a certain processing line, and 2
is the trailing metal band with plate thickness Td and the trailing coil.
As shown in FIG. 2, the vicinity of the rear end of the leading metal band 1 is clamped by clamp devices 3a, 3b, and the vicinity of the tip of the trailing metal band 2 is clamped by clamp devices 4a, 4b. Next, as shown in FIG. 3, the rear end of the leading metal band 1 is trimmed by shearing devices 5a, 5b, and the leading end of the trailing metal band 2 is trimmed by shearing devices 6a, 6b. Next, as shown in FIG. 4, by moving the clamp devices 3a and 3b and/or both of the clamp devices 4a and 4b, the two metal strips are wrapped with a lap distance L corresponding to the thicknesses Tc and Td of the metal strips. Polymerize the ends of the strip. Next, as shown in FIG.
b is rolled under strong pressure in the sheet width direction (direction perpendicular to the plane of the paper), the surfaces to be welded are smoothed and brought into close contact, and the pressing rollers 7a and 7b continue to move. As shown in the figure, electrode rollers 8a, 8b
Electric welding is performed while applying pressure in the width direction of the plate and rolling it. The cross section after welding is as shown in FIG. The welding surface is locally and continuously pressed by pressure rollers 7a and 7b, and then locally by electrode rollers 8a and 7b.
Since continuous welding is performed at 8b, the welding conditions are relatively uniform, and the strength of the welded surface is almost uniform in the width direction of the plate. Therefore, higher welding strength can be obtained than with flash butt welding, and since it is almost uniform in the width direction of the plate, stress concentration is less likely to occur and the rate of breakage accidents during continuous processing is extremely low. Therefore, narrow lap seam welding should be used for all welding, but as the plate thicknesses Tc and Td become thicker, and as the difference in plate thickness (|Tc-Td|) increases, the lap width L must be increased. Therefore, it becomes necessary to apply a strong rolling force to the overlapping portion with the lapping margin L using the pressure rollers 7a and 7b, and as a result, a large component force also acts on the plate in the horizontal direction (X direction in Fig. 5). However, since the plate buckles (this is because the welded joint becomes an inclined surface as seen in the joint cross section of FIG. 7), the lap length L changes in the width direction of the metal strip. That is, as the pressure contact progresses in the width direction, the wrap margin L tends to become smaller. When the wrap length L becomes smaller, not only does the welding surface become narrower, but the welding conditions also change, making uniform welding impossible and reducing the welding strength. For this reason, the welding strength in the width direction of the welded metal strip is not constant, and the welded portion is very likely to break during continuous processing. Therefore, narrow tup seam welding has not been used conventionally for thick materials. The present invention eliminates the drawbacks of conventional narrow seam welding and provides an extremely reliable welding method for joints of thick metal strips. That is, in the joint welding of metal bands together by narrow splice welding, the present invention provides a method in which the peaks and valleys provided on the inclined surfaces of the end portions of both metal bands to be welded engage with each other. A step is formed in advance between the peak and valley so that the overlapping thickness of the mating and interlocking portion is thicker than the plate thickness of both metal strips by an appropriate pressure welding margin, and then electrical pressure welding is performed. Regarding the joint welding method, by forming in advance an engaging part of a shape that meshes with each other on the welding joint surface, it is possible to prevent the overlapping part of both metal strips from escaping in the front and back direction with the lap margin L during conventional welding, and to weld. This makes it possible to weld particularly thick materials. Embodiments of the present invention will be described based on FIGS. 8 and 9. Components that are the same or substantially the same as the conventional ones shown in FIGS. 1 to 7 are designated by the same reference numerals. The explanation will be omitted. FIG. 8 is a width-perpendicular cross-sectional view showing the cross-sectional shape of the surfaces to be welded together at the ends of both metal bands before welding. The cross sections of the surfaces 11 to be welded are inclined to each other, and peaks 9 and troughs 10 are provided on the slopes.
By forming the shapes into shapes that can be joined to each other in this manner, the inclined welding surfaces are in close contact with each other as shown in FIG. Both meshing 9,
The engaged state occurs at a step R between 10 and 10. In other words, the engaging portions 2 that mesh and engage with each other at the step R between the two metal strips 9 and 10 are formed in advance, and then when the engaging portions 12 are pressurized from above and below during welding, the metal strips 1 and 10 are brought into closer contact with each other. , there is no runout at the two ends, and a uniform welding surface is obtained in the width direction, allowing for uniform welding. In this case, the thicker the plate thicknesses Tc and Td of both metal strips 1 and 2, and the smaller the difference in plate thickness (|Tc−Td|), the more uniform the welding allowances Mc and Md will be. Since the welding property can be molded using a single process, weldability can be further improved. By forming the engaging portion into such a shape, a more reliable welded joint can be obtained compared to conventional methods even if the engaging portion is immediately pressurized with an electrode roller and welded with electricity. As shown in FIG. 9, if pressure welding is performed using a pressure roller while leaving pressure welding allowances for Mc and Md, an extremely reliable welded joint can be obtained. Data from experimental examples are shown below.

[Table] The rupture rate of pressure welding is the rate at which a tensile force of 60 kg/mm ² (90% of the tensile strength of the sample material) is applied to the rupture using a tensile testing machine (however, the rupture rate of the online method is 35% compared to the rupture rate of the conventional method). is a few percent of this). As described above, compared to the conventional method, it is possible to greatly improve the reliability of welded joints, especially between thick metal strips, and by directly rolling this joint part during cold rolling with high tension. Since there is almost no need for cutting, it is possible to improve not only rolling efficiency and productivity, but also quality and yield, which can greatly contribute to cost reduction, and has extremely high industrial value.

[Brief explanation of drawings]

FIGS. 1 to 7 are side views illustrating a conventional joint welding method and showing the steps in the order of steps.
FIGS. 8 and 9 are side views showing the process of implementing the present invention. 1... Leading metal band, 2... Trailing metal band, 3a, 3b
...Clamp device, 4a, 4b...Clamp device, 5
a, 5b... shearing device, 6a, 6b... shearing device, 7
a, 7b... Pressure roller, 8a, 8b... Electrode roller, 9... Mountain part, 10... Valley part, 11... Surface to be joined by inclined welding, 12... Engagement part, L... Wrap allowance, Mc,
Md...pressure welding allowance, Tc, Td...plate thickness, R...step difference between peak and valley, X...direction of escape.

Claims (1)

[Scope of Claims] 1. In a method of welding a joint between metal bands by narrow seam welding, the joint has a crest 9 provided on the inclined weld joint surface 11 of the ends of both the metal bands 1 and 2, respectively. and the trough portions 10 mesh and engage with each other, and the peak portions are arranged such that the overlapping thickness of the meshed engaging portions 12 is thicker than the plate thicknesses Tc and Td of both metal bands 1 and 2 by an appropriate pressure welding margin Mc+Md. A metal strip characterized in that the step R between the groove 9 and the valley part 10 is formed in advance, and then the engaging part 12 is immediately energized and welded, or the engaging part 12 is welded by energizing and pressurizing once, or by energizing and pressure welding after being pressure-welded. joint welding method.