JPH10180453A - High-speed non-grinding welding method for tin-free steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the appropriate and stable high-speed welding of a non- ground tin-free steel plate without generating any problems such as generation of dust in manufacturing a can body by the wire seam welding. SOLUTION: In a method to manufacture a can body by performing the wire seam welding of a non-ground tin-free steel plate having a film consisting of a metallic chromium layer of the prescribed chromium adhesion and a chromium hydroxide layer thereon on a surface of the steel plate at the wire feeding speed of >=15 m/min, wires 1, 2 of each electrode to be used on the outer and inner surface side of the can body is 0.5-3.0 mm<2> in sectional area, a straight part 3 whose contour in the width direction of a weld part of a part to be in contact with the steel plate is of the length 1.0-4.0 times the thickness of the steel plate is provided, the inequalities of L<=W<L+1.5 are satisfied where W is the lap width of the steel plates at weld parts, and L is the length of the straight part 3 of the wires of each electrode, the pressure between the electrodes is 30-150 kgf, and the nugget pitch of the weld part is 0.6-1.8 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed non-polishing welding method for manufacturing a can body of a metal container by wire seam welding a tin-free steel sheet.

[0002]

2. Description of the Related Art When manufacturing a can body of a metal container, the thickness of the can is reduced to 0.
As a method of performing wire seam welding on a thin-plated steel sheet having a thickness of about 13 to 0.5 mm, a method is known in which a lap width (lap width) of the steel sheet is set wider than a weld bead width (wire width).
This method was mainly used in the early wire seam welding, and it was not possible to reduce the lap width because the control technology of the weld bead position and the lap width of the steel sheet was not sufficiently established. is there. However, in this method, if the lap width is too large than the weld bead width, the non-welded edges of both edges of the thin plate bend around the welded portion, causing poor repair of the welded portion and deterioration of the corrosion resistance of the can body.

[0003] Further, since the welding conditions could not be stabilized, usable steel sheets have metallic tin on the surface layer,
Tinplate, which had small electric resistance (contact resistance) and was advantageous for fluctuation of welding current, was mainly used. When a tin-free steel sheet (TFS) with high contact resistance is welded at a wire feed speed of 5 m / min or more, the insulating film (the chromium metal layer and the chromium hydrate oxide layer) of the welded portion is polished before welding. It was necessary to reduce the contact resistance by removing by such a method. Further, since a material having a small contact resistance, which is advantageous for the fluctuation of the welding current, is to be welded, if the contact area between the wire and the steel plate is large, a problem arises that the welding current required for proper heat generation becomes too large. In order to avoid such a problem, a wire having an arcuate outer shape in a weld width direction of a portion to be contacted with the steel plate has been used so that the contact area between the wire and the steel plate can be stably and relatively small.

[0004] In contrast to such a conventional wire seam welding method (wide lap welding), a wire seam welding method for a can body, which is currently the mainstream, is a narrow width lap welding as shown in Japanese Patent Publication No. 54-213213. is there. This is a welding method in which the lap width of a steel sheet is reduced to less than half of the welding bead width, and the progress of lap management technology has made such a welding method possible. The advantage of this wire seam welding method is that since the lap width of the steel sheet is smaller than the weld bead width, it is welded including the edges of both edges of the thin plate, so there is no fear of poor repair of the welded part and deterioration of the corrosion resistance of the can body That is the point.
In addition, since the current is effectively concentrated on the plate / plate interface, appropriate heat generation can be obtained with a small current even with a material having a small contact resistance.

[0005] In recent years, regulations on contamination of containers with foreign substances have become strict, and it has become necessary to clean the welding environment. For this reason, there is a growing need to perform high-speed welding of TFS which has been conventionally polished and welded to a welded portion immediately before welding without polishing and in terms of workability.

[0006]

However, when TFS having a high contact resistance is welded at high speed without polishing by narrow lap welding as described above, a welding defect called dust is immediately generated at the plate / plate interface. There's a problem. In other words, in this welding method, the entire lap portion including the edge portion of the steel plate is welded because the wrap width of the steel plate is small, and since the welded portion is mashed with high pressure, dust is generated immediately when excessive heat is generated. Would. For this reason, conventional narrow lap welding
It is not suitable for non-polishing high-speed welding of a material having a high contact resistance such as TFS.

On the other hand, when TFS is welded at high speed without polishing by the conventional wide lap welding as described above,
Under current conditions that can ensure proper heat generation at the board interface, the wire /
There is a problem that dust is generated at the plate interface. This is because, in narrow lap welding, the current density at the wire / plate interface is smaller than that at the wire / plate interface, so that the current density at the wire / plate interface can be reduced and heat generation can be suppressed.
This is because the current density at the wire / plate interface is increased due to a larger current-carrying area at the plate / plate interface than at the plate interface, resulting in excessive heat generation.

Further, in the wire seam welding method, it is difficult to improve the cooling capacity of the wire / plate interface on the inner surface of the can body due to structural restrictions of the welding machine. Therefore, there is a problem that foreign matter is mixed into the can and a weldable current range cannot be secured due to the generation of dust. As described above, in the conventional wire seam welding method, it is practically difficult to manufacture a can body by performing non-polishing high-speed welding of a tin-free steel plate. Therefore, an object of the present invention is to provide wire seam welding that can appropriately and stably perform high-speed welding of an unpolished tin-free steel sheet without causing problems such as dust generation when manufacturing a can body of a metal container by wire seam welding. Is to provide a law.

[0009]

In order to solve such problems, the wire seam welding method of the present invention has the following features. (1) The steel sheet has a coating composed of a metal chromium layer and a chromium hydrated oxide layer thereover on the surface of the steel sheet, and the total coating amount of the coating in terms of metal chromium is 30 to 250 mg / m3 per one side of the steel sheet.
^2, Waiyashimu welding adhesion amount reckoned as metal chromium of hydrated chromium oxide layer has a tin-free steel sheet is steel sheet per side 0.5-15 / m ^2, at 15 m / min or more wire feed speed without polishing In the method of manufacturing the can body by performing the above, the wires of the electrodes used on the inner surface side of the can body and the outer surface side of the can body have a cross-sectional area in a cross section perpendicular to the longitudinal direction of 0.5 to 3.0 mm ^2. The outer shape of the portion to be in contact with the welded tin-free steel plate in the width direction of the welded portion has a linear portion having a length of 1.0 to 4.0 times the thickness of the welded tin-free steel plate. The overlap width W (mm) of the tin-free steel plate to be welded is the length L of the linear portion of the wire of each electrode used on the inner side of the can body and the outer side of the can body.
(Mm), L ≦ W <L + 1.5 is satisfied, the pressure between the electrodes on the inner surface side of the can body and the outer surface side of the can body is 30 to 150 kgf, and the nugget pitch of the welded portion is 0.6.
A high-speed non-polishing welding method for a tin-free steel sheet, which has a thickness of about 1.8 mm.

(2) In the welding method of the above (1), the wires of the respective electrodes used on the inner surface of the can body and the outer surface of the can body are formed in a straight line in the widthwise direction of the welded portion of the portion to be brought into contact with the tin-free steel plate to be welded. A high-speed non-polishing welding method for a tin-free steel sheet, comprising a curved portion having a radius of curvature R of 0.1 mm or more at both ends of the portion.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a tin-free steel plate (hereinafter, referred to as TFS) is used for a non-polishing high-speed welding.
A study was conducted on the optimal width of lapping of steel sheets (lap width) to suppress the generation of dust at the plate interface. As a result, the overlapping width of the steel sheets was reduced in order to avoid the mash at the plate / plate interface and to suppress the generation of dust. The contact width at the wire / plate interface in the weld width direction is set to be equal to or larger than the contact width. However, if the overlap width of the steel sheet is 1.5 mm or more wider than the contact width of the wire / plate interface, a problem of warpage of the steel sheet edge portion occurs, so that repair of the welded portion becomes difficult. For this reason, it is not preferable to make the overlapping width of the steel sheets 1.5 mm or more larger than the contact width of the wire / plate interface.

Here, when the overlap width of the steel sheet is equal to or larger than the contact width of the wire / plate interface in the weld width direction as described above, it is difficult to reduce the amount of electricity at the wire / plate interface. In addition, excessive heat generation at the wire / plate interface becomes a problem. Therefore, as a result of studying to reduce the current density at the wire / plate interface, in order to reduce the current density at the wire / plate interface and suppress excessive heat generation, the outer shape of the portion that should be in contact with the steel plate in the width direction of the welded portion is considered. It has been found that it is effective to use a wire having a linear portion, that is, a wire having a linear contact portion with the steel plate in the weld width direction.

When a wire having a straight contact portion with a steel plate as described above is used when welding a tinplate having low contact resistance or an abrasive of TFS, an excessively large current is required because the energization path is widened. Or exceed the power capacity of the welding machine,
Problems such as an unnecessarily widening of the weld burnt portion and impairing the appearance are caused. On the other hand, when welding a material having a high contact resistance such as unpolished TFS, even if a wire having a straight contact portion with the steel plate as described above is used, the plate resistance is increased due to the surface resistance of the plate. Excessive expansion of the current-carrying path at the / plate interface does not occur. In addition, since the contact between the wire and the steel plate is planar, pressure is evenly applied, so that the energized area is increased as compared with the arc-shaped wire, and generation of dust at the wire / plate interface is suppressed.

When a material having a high contact resistance such as TFS is subjected to wire seam welding, the width of a formed nugget is smaller than that of a material having a low contact resistance such as a tinplate. Therefore, when the length L of the linear portion in the width direction of the welded portion of the wire is less than 1.0 times the thickness of the steel plate, the width of the formed nugget is narrow, and sufficient welding strength required as an actual can is obtained. I can't.
As the length L of the linear portion increases, the width of the nugget increases, and stable welding strength can be obtained even when the conditions during welding change. In particular, it is important to increase the width of the nugget because a material having a high contact resistance has a narrow conduction width. on the other hand,
If the length L of the linear portion exceeds 4.0 times the thickness of the steel sheet, not only the effect of expanding the nugget width is saturated, but also the pressing force and current required for welding become unnecessarily large, which is not preferable. .

Therefore, in the welding method of the present invention, the wires of each electrode used on the inner surface side of the can body and the outer surface side of the can body are
Provided that the outer shape of the portion to be in contact with the TFS to be welded in the weld width direction has a linear portion having a length of 1.0 to 4.0 times the plate thickness of the TFS to be welded. The overlap width W (mm) of the TFS to be welded satisfies L ≦ W <L + 1.5 in relation to the length L (mm) of the linear portion of the wire.

FIG. 1 shows an example of a welding situation according to the method of the present invention in a state where a welded portion is cross-sectionally shown.
Is a wire of an electrode (upper electrode wheel) on the inner surface side of the can body, and 2 is a wire of an electrode (lower electrode wheel) on the outer surface side of the can body.
In addition, the outer shape of the portion of the wire 2 that should come into contact with the steel plate in the width direction of the welded portion has a linear portion 3. For comparison, FIG. 3 shows a welding situation (cross section of a welded portion) according to the conventional method. In FIG. 3, 5 is a wire of an electrode (upper electrode wheel) on the inner surface side of the can body, and 6 is a wire of an electrode (lower electrode wheel) on the outer surface side of the can body. Are all arcuate in the weld width direction.

It is preferable that arc-shaped portions (convex portions) such as arcs are formed at both ends of the linear portion in the width direction of the welded portion of the wire. FIG. 2 shows an example of a welding situation according to the method of the present invention using a wire having such an arc portion,
The cross section of the welded portion is shown, and 4 is an arc-shaped portion formed at both ends of the linear portion 3 of the wire 1 and the wire 2. If such an arc-shaped portion 4 is not provided in the wire 1, if the vertical axes of the upper and lower electrode rings are displaced, the end of the weld bead is flawed, and the flaw is formed when the flange is formed after welding. There is a risk of cracking from the part. In particular, T
When the FS is a thin material having a plate thickness of 0.5 mm or less, such cracks are easily generated. Therefore, it is preferable to form the arc-shaped portions 4 at both ends of the linear portion 3. Further, it is preferable that the radius of curvature R of the arc-shaped portion is 0.1 mm or more in order to obtain the above-described effect.

TFS has a coating composed of a metal chromium layer and a chromium hydrated oxide layer thereover on the steel sheet surface. The high-speed non-polishing weldability of such a TFS material mainly depends on the surface chromium hydration oxide. Depends on the amount of oxide and total chromium. It is considered that a time depending on the adhesion amount of the insulating film is required until the steel sheet is caught between the electrodes during welding and the surface of the insulating film is destroyed to start energization. Also,
Since chromium is a refractory metal, its amount has some effect on weldability. For this reason, in high-speed welding at 15 m / min or more, there is an upper limit of the amount of coating film that can be welded.

Specifically, the total coating amount (total chromium amount) of the coating in terms of metallic chromium is 250 mg / m ² per one side of the steel sheet.
Hereinafter, it is necessary for the high-speed non-polishing welding that the amount of the chromium hydrated oxide layer to be deposited in terms of metal chromium is 15 mg / m ² or less per one side of the steel sheet. When the adhesion amount exceeds these upper limits, there is no weldable current range regardless of welding conditions. Further, the total coating amount (total chromium amount) in terms of metal chromium of the coating was less than 30 mg / m ² per one side of the steel sheet, and the coating amount in terms of metal chromium of the chromium hydrated oxide layer was 0.5 mg / m 2 per one side of the steel sheet. ^If it is less than ² , the corrosion resistance of the weld repaired part cannot be maintained. Therefore, the TF used in the present invention
S is 30 to 250 mg / m ² of the total amount of the coating in terms of metal chromium (total chromium amount) per one side of the steel sheet, and 0.5 to 0.5 in each case of the chromium hydrated oxide layer in terms of metal chromium. １５15 mg / m ² .

The cross-sectional area of the wire used on the inner side of the can body and the outer side of the can body (cross-sectional area in a cross section perpendicular to the longitudinal direction of the wire) is 0.5 to 3.0 mm ² . If the cross-sectional area of the wire is less than 0.5 mm ² , the heat capacity is small and the wire / plate interface cannot be sufficiently cooled. On the other hand, if the cross-sectional area of the wire exceeds 3.0 mm ² , not only does the cooling effect from the viewpoint of heat conduction saturate, but expensive copper wires are unnecessarily used, which impairs economic efficiency. The wire is preferably composed mainly of copper from the viewpoint of heat conduction.

In the present invention, the cross-sectional shape of the wire used for each electrode on the inner surface of the can body and the outer surface of the can body is arbitrary as long as the above conditions are satisfied. A shape (a cross-sectional shape in a cross section perpendicular to the longitudinal direction of the wire) can also be used. Among these, (a) and (b) are modified examples of the wire cross-sectional shape shown in FIG. 1, and (c) and (d) are modified examples of the wire cross-sectional shape shown in FIG. Also, the nugget pitch is an important factor that affects the airtightness of the container. In the case of a material having a low contact resistance and a good pressure contact property, such as a tinplate or TFS abrasive, the energization and heat generation region is wide because the energization is started with a low pressing force, and the weldable nugget pitch is set to a wide range of, for example, 2 mm or more. be able to. Further, since the time from when the steel sheet is caught in the electrode until the start of energization is short, the nugget pitch can be reduced.

On the other hand, when a material having a high contact resistance such as TFS is welded by non-polishing, energization is started only at a high pressing force, so that the energization heat generation area is narrow. If the nugget pitch exceeds 1.8 mm, it is not possible. Since a heat input portion is generated, appropriate airtightness cannot be obtained. In addition, since the time from when the steel sheet bites into the electrode to when energization starts is long, if the nugget pitch is less than 0.6 mm, the range of current that can be welded will be small, and even if the wire shape and coating amount are optimized, welding Appropriate conditions cannot be obtained.

In the case of a material having a high contact resistance such as TFS, by increasing the pressure applied to the upper and lower electrodes, the destruction and press-contact of the film are promoted, and it is possible to secure a stable current path and improve the welding strength. Even if the wire shape and the coating amount are optimized, if the pressure applied between the upper and lower electrodes is less than 30 kgf, the pressure contact will be insufficient, so that the ACR cannot be obtained properly and the sufficient welding strength cannot be obtained. . On the other hand, if the pressing force applied between the upper and lower electrodes exceeds 150 kgf, the steel sheet will not be smoothly bitten between the electrodes, and excessive heat will be generated at the start end of welding due to a change in welding speed. For the above reasons, in the present invention, the nugget pitch is 0.6 to 1.8 m.
m, the pressure between the electrodes on the inner surface of the can body and the outer surface of the can body is 30 to
The condition is 150 kgf.

When a low contact resistance material such as a tinplate or TFS abrasive is welded under the welding conditions of the present invention, the nugget width becomes too wide to impair the appearance or an excessive current is required. The load on the machine power becomes too large and welding becomes difficult. Therefore, when implementing the wire seam welding method of the present invention using an existing welding machine, it is considered that tinplate welding and TFS abrasives are also performed using the same welding machine from the viewpoint of operability. Immediately before the can body inner surface side electrode and the can body outer surface side electrode, a plurality of separate wire forming rolls are respectively arranged so that the wires can be switched appropriately, or a forming roll having a plurality of grooves can be formed on the inner surface of the can body. It is desirable to arrange them immediately before the side electrode and the electrode on the outer surface of the can body, respectively.

[0025]

EXAMPLE A can body was subjected to wire seam welding using an unpolished TFS or tinplate as a raw material, and using a Fuji welder type welding machine in which a steel sheet overlap width was larger than a welding wire width. In this embodiment, the welding speed is 4 to 10 at a welding speed of 10 to 30 m / min.
Conducted continuous can-making of 0 cans, weldable current range (ACR)
Was evaluated and the corrosion resistance of the obtained can body was evaluated. In the evaluation of the cans, the cans whose current was not stable (can bodies made first and last when the can bodies were continuously made) were excluded from the evaluation.

The wire of each electrode was provided with a plurality of grooves on a wire forming roll immediately before the wire was supplied to the electrode, so that the wire had a desired cross-sectional shape. FIG. 5 shows a cross-sectional shape (a cross-sectional shape at a cross-section perpendicular to the longitudinal direction of the wire) of the wire used in this example. Of these, A is a wire having a sectional shape used in the conventional method, and B and C are
Is a wire having a sectional shape used in the method of the present invention. In the example of the present invention, these wires A to C were used in a combination as shown in FIGS.

The ACR is a current range between the lower limit of the current at which a proper welding strength cannot be obtained and the upper limit of the current at which excessive heat is generated. The lower limit current is evaluated by a tear test and the upper limit current is evaluated based on the presence or absence of splash or dust. And evaluated according to the following. ○: Sufficient weldable current range is available △: Weldable current range is available but narrow ×: No weldable current range

The corrosion resistance can be measured at room temperature by filling a water-soluble content into a container manufactured based on each can body except for the can at all times.
The rusting state of the weld repaired part after storage for months was evaluated by the following. ：: no rusting ×: rusting occurred Note that in Examples where there was no weldable current range, the corrosion resistance could not be evaluated because substantial canning could not be performed. The appearance of the weld was visually observed and evaluated as follows. ○: No color unevenness of welded part ×: Color unevenness of welded part

The results of the evaluation of the ACR and the corrosion resistance are shown in Tables 1 to 8 together with the types of the steel sheets and the welding conditions. In Tables 1 to 8, all of the examples of the present invention have a sufficient weldable current range, and the manufactured can bodies have excellent corrosion resistance. On the other hand, Comparative Example 9 in which a wire (wire A) having an arcuate outer shape in a welded portion width direction of a portion to be in contact with a steel plate was used for both electrodes on the inner side of the can body and the outer side of the can body,
In Comparative Example 10, excessive heat was generated at the wire / plate interface, and thus ACR was not properly obtained.

Comparative Examples 1 to 8 and Comparative Examples 11 to
Comparative Example 15 uses a wire having a linear shape in the width direction of the welded portion of a portion to be brought into contact with the steel plate as a wire of the electrode on the inner surface side of the can body and the outer surface side of the can body. Since the present invention does not satisfy the scope of the present invention, the effects of the present invention have not been sufficiently obtained. In Comparative Example 2, the length L (mm) of the linear portion of the wire and the overlap width W (mm) of the steel plate were used.
Is W> L + 1.5, the edge of the steel plate at the welded portion rises up, causing a problem in the sealability of the welded portion, resulting in poor corrosion resistance.

In Comparative Examples 1 and 3, since the cross-sectional area of the wire is less than 0.5 mm ² , the cooling capacity of the wire / plate interface is insufficient, and dust is generated. Therefore, proper ACR
Is not obtained. Further, in Comparative Example 3, since the length L of the linear portion of the wire is less than 1.0 times the thickness of the steel plate, sufficient welding strength required as an actual can cannot be obtained. Furthermore, in Comparative Example 3, the relationship between the length L (mm) of the linear portion of the wire and the overlap width W (mm) of the steel plate is W> L + 1.5, which is outside the scope of the present invention. In Comparative Example 4, the pressure between both electrodes was 3
Since it is less than 0 kgf, ACR cannot be appropriately obtained due to insufficient pressurization, and welding strength becomes insufficient. In Comparative Example 7 and Comparative Example 8, since the pressing force between the two electrodes exceeded 150 kgf, excessive heat generation occurred at the welding start end due to a change in the welding speed due to poor plate biting between the two electrodes. The appearance of the part is inferior.

In Comparative Example 5, since the nugget pitch exceeded 1.8 mm, an unwelded portion was formed between the nugget pitches, so that an appropriate welding strength could not be obtained. In addition, discoloration unevenness occurs in the appearance. In Comparative Example 6, since the nugget pitch is less than 0.6 mm, the heat generation becomes uneven and dust tends to occur. In addition, discoloration unevenness occurs in the appearance.

In Comparative Examples 11 and 12, since the amount of hydrated chromium oxide of TFS and the amount of chromium metal (total chromium amount) each exceeded the upper limit specified by the present invention, the appropriate A
CR has not been obtained. On the other hand, Comparative Examples 13 and 15
Is poor in corrosion resistance because the amount of hydrated chromium oxide of TFS and the amount of chromium metal (total chromium amount) are each less than the lower limit specified by the present invention. Comparative Example 14 is an example in which a tin plate was welded under the welding conditions specified by the present invention.
Is not obtained. Note that the conventional example is an example in which wire seam welding is performed at a low welding speed of 15 m / min or less. When the welding speed is low as described above, the non-polishing welding of TFS is performed with the conventional technology, although the discoloration unevenness of the appearance occurs even in the conventional technology. Indicates that it is possible.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

[Table 6]

[0040]

[Table 7]

[0041]

[Table 8]

[0042]

As described above, according to the present invention, TF
When manufacturing a can body of a metal container by wire seam welding using S as a raw material, non-polished TFS can be appropriately and stably welded at high speed without causing problems such as generation of dust.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a welding situation according to the method of the present invention in a state where a welded portion is cross-sectionally shown.

FIG. 2 is an explanatory view showing another example of a welding situation according to the method of the present invention in a state in which a welded portion is sectioned.

FIG. 3 is an explanatory view showing a welding state according to a conventional method in a state where a welded portion is sectioned.

FIG. 4 is an explanatory view showing an example of a cross-sectional shape of a wire used on the inner surface side of a can body in the method of the present invention.

FIG. 5 is an explanatory diagram showing a cross-sectional shape of a wire used in an example.

[Explanation of symbols]

 1, 2, wire, 3 linear part, 4 arc part

Claims (2)

[Claims] 1. A steel sheet having a coating comprising a chromium metal layer and an overlying chromium hydrate oxide layer on the surface of the steel sheet, wherein the total amount of the coating in terms of metal chromium is 30 to 25 per one side of the steel sheet.
A wire feed speed of 15 m / min or more without polishing a tin-free steel sheet having a chromium hydrated oxide layer of 0.5 mg / m ² per one side of 0 mg / m ² and a chromium hydrated oxide layer of 0.5 to 15 mg / m ² per one side of the steel sheet. In the method of manufacturing a can body by wire seam welding, the wire of each electrode used on the inner surface side of the can body and the outer surface side of the can body has a cross-sectional area of 0.5 to 0.5 in a cross section perpendicular to the longitudinal direction.
A 3.0 mm ^2, linear portion of 1.0 to 4.0 times the length of the plate thickness of the welded tin-free steel sheet and outer shape to be welded tin-free steel plate in the welded portion width direction of the portion to be contacted And the overlap width W (m) of the tin-free steel plate to be welded at the welded portion.
m) satisfies L ≦ W <L + 1.5 in relation to the length L (mm) of the linear portion of each electrode wire used on the inner side of the can body and the outer side of the can body. Pressure between the electrode on the outer side and the outer surface of the can body is 30 to 150 kgf, and the nugget pitch of the weld is 0.6
A high-speed non-polishing welding method for a tin-free steel sheet, which has a thickness of about 1.8 mm. 2. The curvature radius R is set at both ends of a linear portion in a width direction of a welded portion of a portion to be brought into contact with a tin-free steel plate to be welded, the wires being used on the inner surface side of the can body and the outer surface side of the can body. The high-speed non-polishing welding method for a tin-free steel sheet according to claim 1, having an arc-shaped portion of 0.1 mm or more.