JP3153001B2 - Can body having a welding can body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal can used as a container. More specifically, a can body having a can body formed by welding a Cr-plated steel sheet, which causes metal powder contamination of the contents of the can and the can-making environment, and is applied to the can body by welding repair painting. No need for pre-welding treatment such as mechanical grinding or chemical treatment of the steel sheet for welding, which is a factor that hinders the adhesion of the organic film, the necessary and sufficient strength of the welded part and excellent paint adhesion The present invention relates to a can having excellent properties and corrosion resistance, high productivity, and excellent economic efficiency.

[0002]

2. Description of the Related Art Conventionally, gallon cans have been formed such that the rolling direction of a steel strip is perpendicular to the height direction of the can. this is,
Since the carbon content of the conventional steel sheet for cans is not low enough to suppress the increase in hardness that occurs in the weld heat affected zone of the can body, when the can body is welded along the rolling direction, Because of the anisotropy of the rolling texture near the part and the anisotropy of the breaking strength due to the increase in hardness of the weld heat-affected zone, the flange formed part for tightening the can lid cracked and was not practical. Met.

[0003] Gallon cans used for containers such as oils and fats are made using tin-free steel (hereinafter referred to as "TFS"). (Hereinafter referred to as “welding machine”). This is, as we have stated in Materials and Processes, Vol. 4, page 1616,
This is because continuous welding is difficult with an AC power source seam welding machine because the surface of the TFS is covered with a hydrated Cr oxide having high electrical resistance. For this reason, conventionally, in welding TFS, a method of grinding and removing a portion to be welded immediately before a welding operation has been generally used.

However, according to this method, there is a concern that the working environment is deteriorated by the grinding powder, and the content of the can is damaged due to the mixing of the grinding powder into the product can. In the ground portion, the base iron is exposed or the base iron is partially oxidized, and the adhesion of the coating film in the subsequent repair coating is not as good as TFS.

[0005] Therefore, even when the repair coating is performed, problems such as peeling of the coating film and corrosion under the coating film are always included.
In addition, as a matter of course, when the repair coating was not performed, the corrosion of the ground portion progressed very quickly.

Attempts to impart weldability to TFS include Cr
The plating layer is deposited in a granular form, or the Sn plating layer is
Although a method of depositing on the top is known, when a granular Cr layer is used, great care must be taken in controlling the color tone, and when depositing Sn on Cr plating, the Cr hydrated oxide layer is removed. Requires special treatment, and furthermore, there is a problem in operation and quality control such as the adhesion of the coating film on the Sn plating layer is easily lowered. Not widely used.

[0007]

DISCLOSURE OF THE INVENTION The present invention is free from the problems caused by the above-mentioned conventional gallon can molding method, specifically, the contamination of the can-making environment and the contents of the can due to scattering of grinding powder.
It is an object of the present invention to provide a highly reliable can having high adhesion of a coating film in a weld repair painting portion.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have solved the problem of a welding method of a can body formed by welding a can body using a chromium-plated steel sheet as a material by usual pre-grinding of a welded portion. Focusing on the nugget pitch of the welded part, as a result of intensive research on the relationship between plate thickness and nugget pitch, using low carbon steel that has been conventionally used as a steel plate for cans,
In a can body with a can body formed by a welding method, by controlling the weld nugget pitch of the can body to a certain range with respect to the plate thickness, a sound weld appearance, sufficient welding strength, and excellent coating can be obtained. The inventors have found that a can body having both film adhesion and corrosion resistance after coating can be obtained, and have completed the present invention.

That is, according to the present invention, a steel plate shear-formed so that two opposing sides are substantially parallel is formed into a parallel steel plate.
A can body having a welded can body formed by welding two superposed sides by deforming a cylindrical shape with the sides facing each other, wherein the carbon content of the steel sheet is 0.01 to 0.2. weight%
And a metal chromium layer having a basis weight of 300 mg / m ² or less is provided on the surface of the steel sheet.
A chromium hydrated oxide layer having an adhesion amount of 0 mg / m ² or less is provided, the steel sheet is further painted by baking paint, and the nugget pitch of the can body weld is four times or less the sheet thickness. A can body having a welded can body characterized in that the welded portion is not subjected to pre-welding treatment for improving weldability such as mechanical grinding or chemical treatment, and the above object is achieved.

[0010]

[Action] When attempting to perform can body welding in the same way as tinplate with a mash seam welder using a chrome-plated steel sheet, the minimum welding current at which joining at the material interface begins to occur, and the weld is melted and scattered. The welding upper limit current at which whisker-like protrusions, which can be caused by rapid cooling, cause so-called splash, is very close to or reversed, and it is extremely difficult to obtain a sound weld. The difference between the maximum value and the minimum value of the welding current is the weldable current range (ACR), which was very small or was not obtained at all for the chromium-plated steel sheet.

Mash seam welding utilizes Joule heat at the material interface as a heat source for the welding, and therefore the ACR of the material is determined by the interface contact resistance between the materials to be welded and the weld overlap. Greatly varies depending on the accuracy of the overlap width of. Since the ACR varies slightly depending on the production lot of the steel sheet, if the ACR of a certain material is extremely narrow, welding conditions such as welding current must be changed for each incoming lot in the welding process. Can not be used for commercial production. This is why a material with a wide ACR is required.

Splash is generated by excessive heat generated by a welding current and melting of a material in the vicinity of a welding interface. At this time, molten metal is extruded to the outside mainly by an electrode pressing force or the like and solidified by rapid cooling. .

[0013] Since the surface of a chromium-plated steel sheet always has a chromium hydrated oxide layer having a high electric resistance due to the characteristics of the plating reaction, the interface contact resistance becomes higher than that of tinplate and the like. The amount of heat generated per current increases.

In ordinary mash seam welding using an AC power supply, when the welding current is small, the fusion or forging area per individual nugget is small, and as shown in FIG.
An unwelded portion is likely to remain between adjacent nuggets. In such a state, a macroscopically continuous weld cannot be obtained, and a sound product as a can cannot be obtained. When the welding current is increased in order to obtain a continuous welded portion between the nuggets with the nugget pitch as it is, the heat generation at the interface increases rapidly, and a splash is generated as shown in FIG.

Therefore, in the present invention, in order to reduce the welding heat per nugget and obtain a continuous and healthy weld, the nugget pitch of the can body weld is set to four times or less the plate thickness, preferably Determined to be three times or less. This nugget pitch is considered to be a value determined by the balance between the fusion or forge welding of the superposed materials due to heat generation at the interface and the heat propagation inside the material and the heat absorption by the electrodes and atmosphere.

That is, in a region where the nugget pitch is four times or less of the plate thickness, forging or fusion occurs sufficiently due to heat generation based on the contact resistance at the interface, and at the same time, diffusion and absorption of excess heat due to heat conduction inside the material are sufficient. Therefore, no splash occurs. Instead of a short fusion length per nugget, the adjacent nuggets are close enough so that the weld is consequently sound and continuous. Only in this area, when forming a can body using chromium-plated steel sheet as a material, there is no need for pretreatment such as grinding of the welded part prior to the welded part, and the occurrence of splash of the welded part is slight,
A beautiful and strong weld can be formed, and sufficient strength can be obtained.

[0017]

The construction of the present invention will be described below in detail. In the can body of the present invention, a steel plate formed by shearing so that two sides facing each other as a can body are substantially parallel is deformed into a cylindrical shape with two parallel sides facing each other, and the two overlapped sides are welded. Is used. This is a method generally used as a conventional method for welding and forming a can body, and the cross-section at the time of cylindrical forming mentioned here includes various shapes such as a circle, an ellipse, and a polygon. Also, the fact that two opposite sides are substantially parallel means that
It means that it is formed into a cylindrical shape prior to welding and is parallel to the extent that welding is possible when two sides to be welded face each other.

The carbon content of the steel sheet of the present invention is 0.01 to
The range of 0.2% by weight, preferably in the range of 0.01 to 0.1% by weight is because this is an area generally manufactured as a material for cans. If the carbon content is higher than this range, the formability tends to be significantly impaired due to an increase in the hardness of the steel sheet, and control is difficult.

In the present invention, the most important thing is to obtain a robust can body with sufficient sealability, but to ensure moldability in various processes by a conventionally known can body forming method. It is sufficient for the carbon content to be in this range. Further, in the present invention, if it is possible to apply a predetermined chromium plating as a plated steel sheet original sheet, for example, a Ni diffusion layer is formed by heat diffusion treatment after applying Ni plating on the outermost surface of the steel sheet. A surface adjustment original plate can be used, and similarly, a single layer or a plurality of layers of a metal such as Ni, Zn, Sn, Fe, an alloy plating of these metals, an alloy plating of a metal and P, etc. are provided between the chromium plating layer and the original plate. Layers can also be inserted.

The surface of the steel sheet in the present invention 300 mg / m ² or less, preferably the basis weight of the metal Cr layer of 30 to 200 mg / m ^2,
Further 30 mg / m ² or less of metal Cr terms thereon, preferably to that with the provision of the Cr hydrated oxide layer deposition amount of 2 to 20 mg / m ² can been used conventional chrome plated steel cans This is for obtaining sufficient coating film adhesion and corrosion resistance for the intended use.

In the present invention, the nugget pitch of the welded portion of the can body is determined to be four times or less, preferably three times or less the sheet thickness, in this region, when forming the can body using a chromium-plated steel sheet as a material. In addition, no pretreatment such as grinding of the welded portion prior to the welded portion is required, and a beautiful and strong welded portion can be formed with a small amount of splash generated at the welded portion, and sufficient strength can be obtained. This is because the amount of heat input per individual nugget is small, the spread of the heat affected zone is minimized, and the distance between the nuggets is sufficiently close, so that a macroscopically continuous weld is obtained. That's why.

Control of the nugget pitch as described above is achieved by using a means such as appropriately combining the wire electrode feed speed during welding and the frequency of the AC welding power source.

[0023] Chromium-plated steel sheet as a material in the present invention is coated by paint baking, as long as it satisfies the performance that matches the application as the can body, painting or means of coating what kind of type It may be.

[0024]

EXAMPLES The present invention will be described below more specifically based on examples.

Production method of can body : plate thickness 0.14 to 0.32 mm, carbon content 0.02 to
0.25 wt% of aluminum killed cold-rolled steel sheet, per side metallic chromium 87~320mg / ^{m 2,} and further 6~31mg / ^{m 2} adhered to hydrated chromium oxide thereon with the metal chromium amount in terms, can inner-corresponding portion 60 mg / epoxy phenolic resin and 60 mg / epoxyester resin
using dm ² coated chromium plated steel sheet by Sudoronikku manufactured wire seam welding machine to weld molded can bodies by changing the nugget pitch. Table 1 shows the steel sheets and welding conditions used.

[0026]

[Table 1]

Evaluation method The above cans were evaluated by the following methods.

Nugget pitch: The distance between the centers of the nuggets was measured from a micrograph of a longitudinal section of the weld.

Flange crack: The can body after flange formation by a flanger was extracted in the welding process, and the state of crack generation near the weld was visually judged. When no crack was generated, the evaluation was ◎, and when cracks were recognized, the evaluation was x.

Weld strength (peel test): A cut of 3 cm was made at an angle of 45 ° from the edge of the steel plate at one end of the weld of the can body, 3 cm on both sides of the weld, and the part was plied. The continuity of the weld was investigated by a peel test in which the weld was torn off from the can body. ◎ If the weld is continuously torn to the end, × if it breaks in the middle
Was evaluated.

Metal powder contamination in the can: A cellophane tape having a width of 15 mm was applied over 4 cm on the left and right sides of the center of the welded portion in the can body after the welding, and immediately peeled off.
It was put into 50 cc of Cl, boiled for 10 minutes, and Fe and Cr in the leachate were measured by atomic absorption analysis. When Fe or Cr exceeding the measurement limit was detected, x was evaluated, and when not detected, ◎ was evaluated.

Splash generation: Splashes generated on the inner and outer surfaces of the can at the time of welding at the center value of the weldable current range were visually determined as follows. ◎ No splash occurred. ○ Can be covered by repair painting, no problem in sealing and strength. × Cannot be covered with repair painting

Salt spray test: Using a 5% NaCl aqueous solution, a salt water spray tester was used to spray salt water on the weld repair coating portion.
The area of red rust occurrence after 20 days was measured, and the values within ± 20% of the values of the reference examples were evaluated as ○, those exceeding 20% as ×, -20.
% Is less than%.

Table 2 shows the results. From these results, it is clear that the can of the present invention achieves the intended purpose.

[0035]

[0036]

According to the present invention, there can be obtained a can which has no contamination of the can-making environment and the contents of the can due to scattering of the grinding powder, has high adhesion of the coating film at the weld repair coating portion, and has high reliability.

[Brief description of the drawings]

FIG. 1 is a schematic view of a longitudinal section of a welded portion when welding strength is insufficient in conventional Cr-plated steel sheet welding.

FIG. 2 is a schematic view of a vertical section of a welded portion when splash occurs in conventional welding.

FIG. 3 is a schematic view of a longitudinal section of a welded portion in the case of proper welding of a Cr-plated steel sheet in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer steel plate 2 Inner steel plate 3 Fused part, forged part or weld heat affected part 4 Splash 5 Blow hole

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Nobuyuki Morito 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki-Steel Co., Ltd. No. 1 Kawasaki Steel Corporation Chiba Works (72) Inventor Ichiro Kondo 10 Aramaki character Shimogita, Itami City, Hyogo Prefecture Kawatetsu Container Corporation Itami Plant (72) Inventor Shinya Miura Chuo-ku, Chiba No. 1 Shinhama-cho Kawatetsu Inside Chiba Plant of Container Co., Ltd. (56) References JP-A-2-30382 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 8/22 B65D 1 / 12 B65D 25/34

Claims (1)

(57) [Claims] A steel plate formed by shearing a steel plate so that two opposing sides are substantially parallel to each other is deformed into a cylindrical shape with the two parallel sides facing each other, and the overlapped two sides are welded. A can body having a welded can body, wherein the carbon content of the steel sheet is 0.01 to 0.2% by weight,
A metal chromium layer having a basis weight of mg / m ² or less is provided, and a chromium hydrated oxide layer having an adhesion amount of 30 mg / m ² or less in terms of metal chromium is further provided thereon. To
A welded can body characterized in that it is more painted, the nugget pitch of the welded body is no more than four times the sheet thickness, and the welded part of the steel sheet is not subjected to welding pretreatment for improving weldability. A can body having