JPH10216874A - Open end with excellent lid opening property and safety of opening part and production therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the opening property of a scoring part and the safety after opening a can by forming a score part of an open end with pre-shearing from one direction and with return shearing from the reverse direction. SOLUTION: In the score part formed with pre-shearing from one direction and with return shearing from the reverse direction after then, in the time of opening, crack is advanced with the stress concentration caused on acute notches existing on front and back faces. Because a central part to be advanced with the crack is already received with large repeat shearing strain even without generating breaking, the ductility of the material itself is reduced and the crack is advanced easily. Further, in the final shear breaking position (burr generating position), because it is positioned at inner part in the wall thickness direction against the original metal sheet, the ductility of the material is inclined to reducing, so a large burr is not generated, in consideration of the state of generation, the anxiety of a cut of hand or finger, etc., is nothing in the real using.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open end used as a lid of an easy-open can and a method of manufacturing the open end, and more particularly, to openability of a score portion formed in the open end, that is, openability and safety of the opening. Furthermore, the rust resistance of the score processing part is advantageously improved.

[0002]

2. Description of the Related Art A so-called easy open in which cans can be opened without using special tools such as can openers and foods and beverages inside can bodies can be taken out by introducing cuts called scores into the can lid in advance. Cans, beer cans,
It is used for various beverage cans and food cans, including carbonated beverage juice cans. The types are broadly classified into a "pull-off type" in which a tab serving as a so-called "lever" is completely cut off at the time of opening, and a "stained type" in which the tab is attached to the can after opening. Further, there are a partial easy open end in which the opening is made partially with respect to the diameter of the can and a full easy open end in which almost the entire opening is made. Most of the food cans are the latter.

[0003] The above-mentioned scoring has a great effect on the ease of opening the easy-open can lid, that is, the opening property. It is known that the opening property can be improved by reducing the amount of remaining sheet thickness after score processing (score remaining thickness) as much as possible, but it is limited from the viewpoint of maintaining industrial stability and pressure resistance against an increase in internal pressure. was there. In other words, if the score is excessively reduced and the score remaining thickness is reduced too much, cracks may occur in the score portion during processing, or thermal internal pressure may increase during transportation or storage, or impact stress may increase. This increases the risk of causing a problem such as leakage of the contents due to the application.

A conventional technique is disclosed in Japanese Patent Application Laid-Open No. 54-54786.
JP, JP-A-57-175034 and JP-A-62-23
The technology disclosed in Japanese Patent Publication No. 5053 is known. These are all techniques relating to the formation of the score portion, and although the effect of improving the opening property can be seen, it was not always sufficient. On the other hand, by dispersing coarse non-metallic inclusions in steel,
There have been some proposals to facilitate fracture as a starting point for voids, and although opening is certainly improved under ideal conditions, in practice the dispersion of these non-metallic inclusions is extremely uneven. As a result, unexpected unstable destruction is caused, and there is a problem in reliability. In addition, since these materials inevitably decrease in formability, there is a problem in that cracking occurs when so-called rivet processing required for fixing the tab is performed, making molding impossible.

[0005] One of the drawbacks of the iron easy-open can lid is that it is essential to take measures against rust in the score processing portion. In this type of can lid, since openness is a top priority,
Although a sharp cut (score) is provided, even if a surface-treated steel sheet is used, exposure of the ground iron is unavoidable, and rust generated during storage becomes a serious problem in this state. Therefore, the iron easy-open lid had to be repair-painted on the processed part after score processing,
This is an extra step, and is extremely disadvantageous in terms of cost.

[0006] In this regard, a technique that eliminates the need for repair coating after forming a score by utilizing extrusion or pressing is disclosed in JP-A-6-115546-115548 and JP-A-7-5105.
No. 1779 and Japanese Patent Application Laid-Open No. 8-99140. However, although these techniques can considerably improve the corrosion resistance of the score-processed portion by using a material having a resin film, they cannot be said to be sufficient yet because the distortion of the score-processed portion is wide. Furthermore, in the case of the full open end, since the burr of the cut exists in a sharp form, there is a problem that the hand, finger, mouth and the like are cut, and it is not enough to secure the safety of the opening. I couldn't say.

[0007] As described above, when the easy-open can lid is opened and used, the hand, finger, lip, and the like often come into contact with the fractured surface. Is difficult to cut, in other words, ensuring safety after opening cans is also an important requirement.

In this regard, regarding the manufacturing method of the easy-open can lid, there are Japanese Patent Application Laid-Open Nos. 60-204452 and 62-64729 as techniques for improving the safety of the cut surface.
These technologies form the cross-sectional structure of the notch of the lid (open the lid along it) into a complex shape as if the plate were folded, and use the elastic restoring force,
By preventing a sharp cut from being isolated and exposed, it is intended to prevent a cut accident such as a user's hand or finger. However, with the above technique,
Although safety can be improved, it is difficult to apply when the area of the cut is small, and there remains a problem in that a complicated mold requires many processing steps.

[0009]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and, of course, has excellent openability of the score processing portion, excellent safety after opening the can, and It is an object of the present invention to propose an open end of an easy-open can having excellent rust resistance of a score processing portion together with an advantageous manufacturing method thereof.

[0010]

Means for Solving the Problems Now, the present inventors have studied the applied materials, and found that the conventional method of simply making the material brittle involves manufacturing the original material into a uniform material. In addition to the difficulties themselves, it became clear that the reliability after being assembled as a can was raised. Therefore, as a raw material, various molding methods were intensively studied in order to secure the opening property, the safety of the cut end, and also the corrosion resistance while utilizing the excellent ductility of iron. As a result, the following remarkable findings were obtained.

1) The energy required for the opening is lower when the cuts exist on both sides than in the conventional score shape in which the cuts exist only on one side of the plate surface. 2) For the same remaining score, the sharper the cut, the lower the energy required for opening. 3) In the processing of the score portion, the strength of iron can be reduced more effectively by performing repetitive processing in which processing is performed in one direction first and then performed in the opposite direction, rather than processing in a single direction. . 4) In the case of 3), the occurrence of so-called "burrs" at the final breaking position is small. 5) In the case of the above 3), although the opening strength is reduced, the rigidity of the can lid material against the increase in internal pressure and the application of an impact load is sufficiently high. 6) In the processing with a large amount of strain in a single direction, there is a limit in the ability to follow the deformation of the plating layer and the coating layer on the surface, and these layers are easily peeled to expose the base iron. If so, these layers have good followability to deformation of the ground iron, and exposure of the ground iron can be effectively prevented.

The present invention has been developed as a result of intensive studies on control of the score portion shape and optimization of the machining history based on the above findings. That is, the gist configuration of the present invention is as follows. 1. An open end of an easy-open can, wherein a score portion of the open end is formed by preliminary shearing from one direction and return shearing from the opposite direction, wherein the lid is easily opened and the opening is safe. An open end with excellent characteristics.

2. The open end according to 1 above, wherein the amount of preliminary shearing from one direction is 10 to 50% of the plate thickness, and which is excellent in lid opening property and opening safety.

3. In the above item 1, the shear fracture portion caused by the preliminary shearing process and the return shearing process is 30 to 90% of the plate thickness.
An open end with excellent lid opening and opening safety.

4. In the above 1, 2, or 3, an open end excellent in lid opening property and opening safety, wherein the score portion is subjected to heat softening after preliminary shearing and return shearing.

5. In the above 1, 2, 3, or 4, an open end excellent in lid opening properties and opening safety is made of a cold-rolled steel plate for the easy-open can.

6. In the above item 5, the cold-rolled steel sheet as the material of the easy-open can has a C content of 0.1 wt% or less and a Si content of 0.30%.
wt% or less, Mn: 1.00wt% or less, Al: 0.005 to 0.20wt%,
N: An open end containing 0.020 wt% or less, with the balance being substantially a Fe composition. Excellent openability and open safety.

[7] In the above item 5, the cold-rolled steel sheet as the material of the easy-open can has a C content of 0.1 wt% or less and a Si content of 0.30%.
wt% or less, Mn: 1.00wt% or less, Al: 0.005 to 0.20wt%,
N: 0.020 wt% or less, and Nb: 0.003 to 0.02 wt%
%, Ti: 0.003 to 0.02 wt%, B: 0.0005 to 0.004 wt%, one or more of which are selected, and the balance is substantially Fe composition. Open end with excellent opening safety.

8. In the above 5, 6 or 7, the cold-rolled steel sheet as the material of the easy-open can has a surface treatment layer on its surface, and the lid-opening property, the safety of the opening and the rust resistance of the score-processed part Excellent open end.

9. In the above item 8, the surface treatment layer is made of one or more of a metal-based plating layer and an organic resin coating layer, or a composite layer of both of them, wherein the lid-opening property, the safety of the opening, and the rust resistance of the score-processed portion are provided. Excellent open end.

10. In the above item 9, the surface treatment layer is an Sn-plated layer, and the open end is excellent in lid opening property, opening safety, and rust resistance of the scored portion.

11. The open end according to the above item 10, wherein the ground iron surface layer has a diffusion layer of Ni, and is excellent in lid opening property, opening safety, and rust resistance of the score processing portion.

12. In 9 above, an open end in which the surface treatment layer is a Cr plating layer, which is excellent in lid opening properties, opening safety, and rust resistance of the score-processed portion.

13. In any one of the above 5 to 12,
An open end with excellent lid opening and opening safety, characterized by having a decarburized layer on the surface of the ground iron.

14. In any one of the above items 1 to 13,
An open end made of a work-hardened metal plate with excellent lid opening and opening safety.

15. In the method of manufacturing an open end of an easy open can, in forming a score in the open end, first, a preliminary shearing process is performed from one direction to a score processing assumed portion, and then a return shearing process is performed from the opposite direction. An open-end manufacturing method characterized by excellent lid opening properties and opening safety.

16. In the above item 15, the method for producing an open end excellent in lid opening property and opening portion safety, wherein the amount of preliminary shearing processing is 10 to 50% of the plate thickness.

17. In the above 15 or 16, the method for producing an open end excellent in lid opening property and opening safety, wherein a shear fracture portion by pre-shearing processing and return shearing processing is 30 to 90% of a plate thickness.

18. In the above 15, 16 or 17, the method for producing an open end excellent in lid opening properties and opening safety is provided, wherein the material of the easy open can is a cold rolled steel sheet.

19. In the above item 18, the cold-rolled steel sheet as the material of the easy-open can has C: 0.1 wt% or less, Si:
0.30wt% or less, Mn: 1.00wt% or less, Al: 0.005 to 0.20wt
%, N: 0.020 wt% or less, the balance being substantially Fe composition, an open-end manufacturing method excellent in lid opening property and opening safety.

20. In the above item 18, the cold-rolled steel sheet as the material of the easy-open can has C: 0.1 wt% or less, Si:
0.30wt% or less, Mn: 1.00wt% or less, Al: 0.005 to 0.20wt
%, N: 0.020 wt% or less, and Nb: 0.003 to 0.1%.
02wt%, Ti: 0.003-0.02wt%, B: 0.0005-0.004wt
%, Wherein the composition contains one or more kinds selected from the group consisting of at least one and the balance substantially of Fe.

21. In the above 18, 19 or 20, the cold-rolled steel sheet as the material of the easy-open can has a surface treatment layer on its surface, wherein the lid-opening property, the safety of the opening and the rust resistance of the score-processed part are characterized. Excellent open-end manufacturing method.

22. In the above item 21, the surface treatment layer is
An open-end manufacturing method comprising a metal plating layer and an organic resin coating layer, which is a single layer or a plurality of layers or a composite layer of both, and is excellent in lid opening property, opening safety, and rust resistance of a score-processed portion.

23. In any one of the above items 18 to 22, the steel sheet is put into the steel plate for 150 to 25 at the time of or after the processing of the score portion.
An open-end manufacturing method characterized by heating to 0 ° C., which is excellent in lid opening property, opening safety, and rust resistance of a scored portion.

24. In the above item 23, when the surface treatment layer includes an organic resin coating layer, the heating temperature is set to be equal to or higher than the glass transition point of the organic resin. Open-end manufacturing method with excellent performance.

25. In the above item 23, the surface treatment layer is formed of Sn
A method for producing an open end which is excellent in lid opening property, safety of an opening, and rust resistance of a score-processed portion, wherein a heating temperature is equal to or higher than a melting point of Sn when the plating layer is used.

26. In 22 above, when the surface treatment layer is a Sn plating layer, or in 25 above, a Ni diffusion layer is previously formed on the surface of the base iron, An open-end manufacturing method with excellent rust resistance in the processed part.

27. In any one of the above items 18 to 25, the cold-rolled steel sheet as a material is characterized by omitting annealing after cold rolling, and is excellent in lid openability, safety of an opening, and rust resistance of a score-processed portion. Open-end manufacturing method.

28. In any one of the above items 18 to 26, a method for producing an open end excellent in lid opening property and safety of an opening, wherein decarburization of 5 ppm or more is performed in an annealing step of a cold rolled steel sheet as a material.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a score, which is a feature of the present invention, will be described below. 1) Preliminary processing is added to the score processing assumed part (see FIG. 1). As shown in FIG. 1, preliminary shearing is performed from one direction to the score processing assumed portion. As a result of this processing, the surface layer is in a state where shear fracture has occurred, and the central part is in a state where it has been subjected to shear processing. 2) Next, a return shearing process is applied to the preliminary shearing portion from the opposite direction (see FIG. 2). By this return shearing process, the material surface returns to a substantially initial flat state. 3) Finally, 30 to 90% of the total plate thickness is subjected to shear fracture (see FIG. 3). By adding the processing histories 1) and 2) to the score processing assumed part, when viewed in the thickness direction,
On the front and back sides, sharply shaped (and small opening, that is, closed) cracks (shear fractures) were formed, and the central part was subjected to strong cyclic shear strain occupying 10 to 70% of the plate thickness. There will be parts.

At the time of opening, the score formed as described above cracks due to large stress concentration due to sharp notches on the front and back surfaces. Although the part where the crack progresses has not fractured, it has already been subjected to large repeated shear strain, and the ductility of the material itself has been reduced, so that the crack easily propagates. Further, the final shear fracture position (burr generation position) is at least equivalent to the inner part of the original sheet material in the thickness direction, and the ductility of the material tends to decrease, so that a large burr is generated. Therefore, there is no possibility that a cut of a hand or a finger may occur in actual use from the occurrence mode.

The rust resistance of the opening is explained as follows. That is, when a plating layer of tin or the like is present in advance, a part of the layer is peeled off by the pre-shearing process, but the amount is small, and most of the layer covers the surface following the steel sheet. In such a state, further shearing in the opposite direction as in the present invention is in a direction to recover the coating of the plating, and an effect of gathering the coating material on the sheared portion can be expected. Therefore, at the time of completion of the molding, the exposure of the underlying iron is very slight. Further, if a heat treatment is performed thereafter, the broken portion of the plating layer is repaired by the reflow effect, so that the rust resistance is completely recovered.

Hereinafter, the present invention will be described specifically. First, the application range of the present invention will be described. The score forming technique according to the present invention can be applied to all conventionally known easy-open cans such as aluminum cans and steel cans. As the applicable material, any metal material having sufficient formability can be advantageously applied, but aluminum materials for cans and steel plates for cans are particularly suitable. Here, the preferred composition of the aluminum material for cans is as follows. Mn: 5 wt% or less, Mg: 7 wt% or less The final strength is adjusted by adjusting the temper rolling performed after annealing, but these elements are useful for securing sufficient ductility and strength at that time. And also has the effect of preventing deterioration of corrosion resistance. For that purpose, it is preferable to add each in the above range. The other alloy elements are not particularly limited, and can be used in a usual range.

On the other hand, the preferred composition of the steel sheet for cans is as follows. That is, C: 0.1 wt% or less, Si: 0.30 wt% or less, Mn: 1.00 wt% or less, Al: 0.005 to 0.20 wt%, N: 0.
020 wt% or less, and if necessary Nb: 0.003-0.
02wt%, Ti: 0.003-0.02wt%, B: 0.0005-0.004wt
%, One or two or more selected from among the other components, with the balance being substantially Fe.

The reasons for limiting the component composition in the preferred material steel sheet to the above range are as follows. C: 0.1 wt% or less If the C content exceeds 0.1 wt%, the fraction of carbides present in the steel sheet increases rapidly, and the ductility of the steel sheet deteriorates remarkably. Therefore, the C content should be 0.1 wt% or less. Is preferred. Further, from the viewpoint of workability, the content is desirably 0.02% by weight or less. Although the lower limit is not particularly set, the C content is 0.0005wt%.
If it is less than 1, the crystal grains become remarkably coarse, and the risk of occurrence of a rough skin defect similar to the so-called orange peel phenomenon increases. Therefore, the C content is desirably 0.0005 wt% or more. Further, when high material stability and excellent ductility are required, the range of 0.0015 to 0.015 wt% is desirable.

Si: 0.30 wt% or less If Si is excessively contained, the surface treatment property is deteriorated, and problems such as deterioration of corrosion resistance are caused.
wt%. If excellent corrosion resistance is required, 0.
It is preferably at most 02 wt%.

Mn: 1.00 wt% or less Mn is an effective element for preventing hot cracking due to S, and must be added according to the S content. Mn is
Such an addition is desirable in terms of the material because it has the effect of making the crystal grains fine. On the other hand, if a large amount of Mn is added, not only corrosion resistance is deteriorated, but also the steel sheet is hardened, cold rolling is deteriorated, and finally the opening property as a cover material is deteriorated. %. For applications requiring better corrosion resistance and moldability, the content is preferably 0.60% by weight or less, more preferably 0.20% by weight or less.

Al: 0.005 to 0.20 wt% Al needs to contain at least 0.005 wt% as a deoxidizing agent, but as the content increases, the surface properties deteriorate and solid solution N
, The upper limit was set to 0.20 wt%. From the viewpoint of material stability, 0.008 to 0.
060 wt% is desirable.

N: 0.020 wt% or less When the N content exceeds 0.020 wt%, not only the incidence of surface defects on the steel sheet increases, but also the occurrence of slab cracks and the like during continuous casting becomes remarkable. The upper limit is set to 0.020 wt%. By strengthening the steel by adding N, it is possible to improve the pressure resistance and impact resistance of the can lid, and it is also possible to reduce the thickness of the steel sheet while maintaining them at a sufficient level. Further, even when such solid solution strengthening of N is used, the lid material of the present invention has a feature that the opening property is hardly deteriorated. Note that the lower limit is not particularly defined, but when the strength as a cover material is required, the above-described desirable effects can be exhibited by adding approximately 30 ppm or more of N. In addition, from the viewpoint of improving the stability and yield of the material considering the entire manufacturing process, 0.015 wt
% Is more preferable. In particular, in applications where the strength as a cover material is not required, it is desirable to use low nitrogen steel of about 20 ppm.

Although a steel material satisfying the required characteristics can be obtained with the above-described steel composition, it is advantageous to selectively add Nb, Ti and B as elements for further improving these characteristics. Nb: 0.003 to 0.02 wt% By adding Nb, the microstructure of the steel sheet can be refined. After EOE processing,
The reliability against an impact load applied until use is significantly improved. Such an effect is obtained from the addition of approximately 0.003 wt% or more. However,
Even if it is added in excess of 0.02 wt%, these effects are saturated and the recrystallization temperature is significantly increased, so that it becomes difficult to perform an annealing treatment when manufacturing a steel sheet. Therefore, the amount of Nb added is
It is preferable that the content be about 0.003 to 0.02% by weight.

Ti: 0.003 to 0.02 wt% By adding Ti, it is possible to refine the microstructure of the steel sheet similarly to Nb. In addition, the addition of Ti achieves morphological control of inclusions, and after EOE processing, the reliability against impulsive loads applied by the time of use is significantly improved. Such an effect is obtained from the addition of approximately 0.003 wt% or more. However, even if it is added in excess of 0.02 wt%, not only these effects are saturated, but also the recrystallization temperature is significantly increased, so that it becomes difficult to perform an annealing treatment when manufacturing a steel sheet. Therefore, it is preferable that the amount of Ti added be about 0.003 to 0.02 wt%.

B: 0.0005 to 0.004 wt% By adding B, the formability of the steel sheet, particularly the local ductility, can be improved. This effect is exhibited only at 0.00
This is due to the addition of 05 wt% or more. However, 0.0040wt
%, The effect is saturated, the yield stress increases, and the workability deteriorates. Therefore, the amount of B added is preferably about 0.0005 to 0.004 wt%. Note that the above-mentioned Nb, Ti, and B are not only added alone, but also when two or more kinds are added in combination.
Each effect is not offset.

Cold rolling obtained by subjecting a steel slab adjusted to the above-mentioned preferred composition to hot rolling, pickling, cold rolling, annealing and then light skin pass or secondary cold rolling of about 5 to 30%. A steel sheet is used as a raw material, and a surface-treated steel sheet in which the surface of the cold-rolled steel sheet is coated with a metal plating such as electrotin plating or chromate treatment or an organic resin coating such as a PET film or a paint is more advantageous.

Next, preferred conditions for producing the above steel material will be described. The slab is desirably manufactured by a continuous casting method in order to prevent macro segregation of components. The continuously cast slab may be once cooled to room temperature as it is, or may be directly charged into a heating furnace at a high temperature without cooling.

Although the finish rolling temperature is not particularly restricted, by setting it at 850 ° C. or higher as usual, a uniform and fine hot-rolled base plate structure can be obtained, thereby making the structure of the final product uniform. Miniaturization can be achieved. However, at a finish rolling temperature exceeding 950 ° C., the generation of flaws due to scale becomes remarkable, which is much less preferable in the field of steel sheets for cans where surface soundness is strongly required. The temperature is more preferably in the range of 880 to 920 ° C. from the viewpoint of material uniformity. Although there is no particular restriction on the hot-rolling winding temperature, an intermediate temperature of about 550 to 750 ° C is recommended, as is usually the case with ultra-thin steel base plates for cans. .

Annealing conditions: not less than recrystallization temperature and not more than 800 ° C. In order to improve the ductility of the material, annealing at not less than the recrystallization temperature is essential. However, when the annealing is performed at a temperature exceeding 800 ° C., remarkable grain growth occurs, so that the risk that the surface roughness after forming becomes apparent increases. Therefore, the annealing temperature is preferably not lower than the recrystallization temperature and not higher than 800 ° C. 0.35mm thickness
In the following extremely thin steel plates for cans, annealing at a lower temperature and for a shorter time (approximately 20 seconds) is advantageous from the viewpoint of improving productivity.

Cold rolling reduction after annealing; light skin pass or 5% or more and 40% or less Secondary cold rolling after annealing is performed for the purpose of adjusting the surface condition of the steel sheet and adjusting the strength level according to the use. You. If a light skin pass of about 1% or more is not performed after annealing, the detailed mechanism is unknown, but the surface is deformed unevenly, or the beauty of the processed surface is significantly reduced as a product. When the rolling reduction exceeds 40%, the ductility deteriorates remarkably,
The risk of breakage during molding increases.

Continuous Rolling (Endless Rolling) with Sheet Bar Joining at the End of the Finishing Rolling Machine By performing endless rolling, hot rolling at the leading and trailing ends of the steel strip can be performed under more steady conditions. Therefore, the uniformity of the material in the longitudinal direction can be stably enhanced. In addition, according to this method, the leading and trailing end plates are stably passed, so that the shape and dimensions of the hot-rolled mother plate serving as the base plate of the final product can be secured with extremely high accuracy.

Performing lubricating rolling with a coefficient of friction of 0.2 or less during hot rolling By lubricating rolling during hot rolling, the detailed mechanism is unknown. Variations in material can be reduced. Presumably, it is presumed that various metallurgical phenomena at the time of transformation / precipitation progress more uniformly by making the strain distribution in the thickness direction more uniform during hot rolling. As a result of investigating changes in materials by changing the lubrication conditions during hot rolling variously, it is remarkable that the friction coefficient during rolling is 0.2 or less, more preferably 0.15 or less, whatever the lubricant used The effect of uniform material quality was obtained.

Surface Treatment The cold-rolled steel sheet manufactured as described above is usually subjected to a surface treatment for improving rust resistance. Such a surface treatment may be any as long as it is applied to a normal steel sheet for cans. For example, as a metal plating, tin plating, chromium plating, nickel plating, nickel-chromium plating, and further chromate treatment and so on. Examples of the organic resin coating include an organic resin film such as PET and a paint. The above-mentioned metal plating and organic resin coating may be either a single layer or a plurality of layers, respectively, and there is no problem as a composite layer of metal plating and organic resin coating.

Although the typical method of manufacturing a cold rolled steel sheet has been described above, the use of a work-hardened metal sheet by omitting the annealing step in the above steps is not sufficient in strength as a lid material. And it is advantageous in that the same lid material strength can be secured with a thinner thickness. This is because the cost of the metal material used per can can be reduced by using a thinner material having higher strength.

This method of omitting annealing is based on the fact that the amount of C
This is particularly effective when using a high-purity ultra-low carbon steel of 0.0015 wt% or less. In addition to the manufacturing cost advantage of omitting the annealing step, the surface concentration of alloying elements (during annealing)
There are advantages such as improvement of corrosion resistance because there is no. It should be noted that even if the annealing is omitted in this manner, there is no disadvantage to the openability and the safety of the opening.

In the above annealing step or separately, decarburizing treatment to form a decarburized layer on the surface of the steel sheet is advantageous in that the opening property can be further improved when a cover material is formed, and This is advantageous in that the wear of the mold (tool) during molding can be reduced and the life of the mold can be extended. However, this effect is not sufficiently exhibited if the decarburization amount is less than 5 ppm. Therefore, when such a decarburization treatment is performed, the decarburization amount needs to be 5 ppm or more. In addition, as the decarburization treatment means, it is advantageous to adjust the hydrogen gas concentration, the dew point, and the like in the continuous annealing furnace.

A score portion is formed on the material manufactured as described above as follows. That is, as shown in FIG. 1 described above, preliminary shearing is performed from one direction to the score processing assumed portion. As a result of this processing, a portion where a shear fracture has occurred is generated in the surface layer portion, and a portion where the shearing process has been performed occurs in the center portion. In order to improve the openability, it is desirable to perform a larger shearing process at this stage, but the processing amount is 50
%, A satisfactory score portion strength cannot be secured after the return shearing process described later. On the other hand, by performing preliminary shearing of approximately 10% or more with respect to the entire plate thickness, it is possible to finally form a score portion having an excellent opening property. Therefore, the amount of preliminary shearing is set to about 10 to 50%. Is preferred. At this time, the setting of the clearance affects the shape of the crack (notch) part that finally remains. Although setting a small clearance is advantageous because a sharper cutout portion can be finally formed, setting an excessively small clearance is disadvantageous in terms of mold wear and the like. Generally + 10% of board thickness
~ -10% is recommended.

Next, a return shearing process is applied to the preliminary shearing portion from the opposite direction. This step is most desirably performed in exactly the reverse of the above-described pre-shearing, but as shown in FIG. 2 described above, the sheared portion is returned to a flat state before pre-shearing by simple means such as compression and pressing. By doing so, a similar effect can be obtained. In addition,
At this time, it is important to apply reverse shearing, and it is not always essential to completely return to the initial flat state. In addition, the amount of shear fracture introduced into the lower surface of FIG. 2 by the back shearing tends to be smaller than the amount of preliminary shearing due to plastic deformation. For this reason, even if the pre-shearing processing of about 50% is performed and the same degree of return processing is performed, the shear fracture portion does not necessarily penetrate.

By adding the processing histories 1) and 2) to the score processing assumed portion, as shown in FIG. 3 above, when viewed in the plate thickness direction, the front and back sides have sharply cracked portions. That is, there is a shear fracture part, and the central part
There will be parts that have been subjected to strong cyclic shear strains, accounting for ~ 70%. 30 parts are sheared
% Or more, the opening property (reduction of force required for opening and energy) is remarkably improved. However, when this portion exceeds 90%, the strength of the single body is remarkably reduced, and the reliability against the increase in the internal pressure of the can, the impact stress and the like is remarkably reduced. Therefore, it is preferable that the shear fracture portion is about 30 to 90% of the total plate thickness.

The score formed as described above is
At the time of opening, cracking easily proceeds, so there is no problem in terms of opening properties. In addition, the final shear fracture position (burr generation position) is at least equivalent to the inner part of the original sheet material in the thickness direction, and the ductility of the material tends to decrease, so large burrs are generated. Therefore, the safety of the opening after opening the can is also excellent. Furthermore, when there is a plating layer such as tin beforehand, although a part is peeled off by shearing, the amount is small, and some repair is made by reverse shearing in the opposite direction,
Also improves rust resistance. In addition, if a heating softening treatment is performed during or after the score processing, the ductility of the strongly processed portion can be appropriately recovered, and unstable destruction can be prevented, and the reliability of the container during storage is improved. be able to. In the case where a cold-rolled steel sheet is used as the material, such a softening treatment is preferably performed at 150 ° C. or higher in order to obtain a sufficient softening effect. Heating at more than 250 ° C. is not preferable from the viewpoint of generating a temper color. In addition, it is advantageous to add a heat treatment that gives a softening of 10% or more even in cases other than cold-rolled steel sheets.

Further, by the above-mentioned heat softening treatment, the broken part of the surface treatment layer is repaired by the reflow effect, and the rust resistance effect is completely restored. When the surface treatment layer is an Sn plating layer, the melting point is preferably not less than the melting point of Sn (232 ° C.), and when the surface treatment layer is an organic resin coating layer, the melting point is desirably not less than the glass softening point.

Furthermore, when Sn plating is applied as the metal plating, it is advantageous to form a Ni diffusion layer on the surface of the ground iron in advance. This is because, if a Ni diffusion layer is formed in advance on the surface of the ground iron, the electrochemical potential difference in the layer structure becomes small, so that the corrosion rate is significantly reduced. The formation of such a Ni diffusion layer,
This is achieved by applying thin plating of about 0.10 g / m ² or less on the inlet side of the continuous annealing furnace and annealing under ordinary conditions.

[0070]

【Example】

Example 1 As an open end material, an Al alloy (JIS H4000; 5182 series) having a plate thickness of 0.27 mm was used. For this Al alloy material, as shown in FIGS.
Pre-shearing was performed with various processing amounts as shown in Table 1 and then back-shearing was performed with various processing amounts as shown in Table 1 to form a score portion having a shear fracture portion ratio shown in Table 1. . In some cases,
Heat softening treatment was performed at 20 ° C. for 20 minutes. Table 1 also shows the results of an investigation on the openability and the safety of the opening when the open-end score section thus obtained was opened.

The opening property is determined by applying a tensile load to a tensile tester and measuring the pop value measured from the load-displacement relationship.
Evaluation was made based on the tear value and the detach value (both were averages of N = 10). Here, the pop value is the stress required to generate an initial crack by raising a tab, the tear value is the stress required to stably continue shear fracture at the score, and the detach value is the tab detached from the lid body. Is a value that depends on the plate thickness, design, etc., but it is 2.0, 3.5, 4.0
If it is about kgf or less, it can be said that the opening property is generally good.
In addition, Table 1 also shows, for comparison, the results of an investigation in which a score portion was formed by a press notch from one direction according to a conventional method.

[0072]

[Table 1]

As is clear from the table, all of the open ends obtained according to the present invention were excellent not only in the openability of the scored portion but also in the safety after opening the can. On the other hand, the one obtained according to the conventional method requires a relatively high level of force required for opening, and sharp burrs are produced with the risk of cuts of hands, fingers and the like.

Example 2 C: 0.03 wt%, Si: 0.02 wt%, P: 0.00
5 wt%, Mn: 0.15 wt%, Al: 0.045 wt%, S: 0.010 wt
% And N: 0.0035 wt%, the balance being a steel slab substantially having the composition of Fe under the following conditions:-Slab heating temperature: 1250 ° C-Finish rolling temperature: 850 ° C-Finish thickness: 2.0 mm-1 Secondary cold rolling reduction: 90% • Annealing: continuous annealing (700 ° C-20s, no overageing) • Secondary cold rolling reduction: 1.5% (skin pass) cold rolled steel sheet (thickness: 0.20mm) and its surface A 25 # tin plate plated with Sn at a basis weight of 2.8 g / m ² was used. In addition, about the tin plate, the epoxy-ester type | system | group coating was given and used for the test. An oval shape (length 40 mm, radius 10 mmφ) was applied to each of the above-mentioned steel sheets in the same manner as in Example 1.
(−20 mmφ). In addition, a part was subjected to heat softening treatment at 210 ° C. for 20 minutes. Table 2 also shows the results obtained by investigating the opening properties, opening safety, and rust resistance when the thus obtained open end score is opened. Here, the rust resistance was evaluated by maintaining the material for about one month in an environment where dew condensation and drying were repeated, and by evaluating the occurrence of rust on the surface, particularly in the score forming portion. In addition, Table 2 also shows, for comparison, the results of an investigation in which a score portion was formed by a press notch from one direction according to a conventional method.

[0075]

[Table 2]

By performing the score processing according to the present invention, it was possible to obtain an open end excellent in openability of the score portion, safety of the open portion, and rust resistance. In particular, it was confirmed that when heat treatment was performed after scoring, rust resistance was further improved.

Example 3 A steel slab having the composition shown in Table 3 was treated under various conditions shown in Table 4 to obtain a cold-rolled steel sheet. Next, for a part of the cold rolled steel sheet, a metal plating layer such as Sn plating and Cr plating or an epoxy amino clear
An organic resin coating layer such as an ET film, and a composite layer of a metal plating and an organic resin were formed. An oval shape (length 40 mm, radius
An open end score of 10 mmφ-20 mmφ) was formed. Table 5 shows the results obtained by examining the openability, the safety of the opening, and the rust resistance when the thus obtained open end score is opened.

[0078]

[Table 3]

[0079]

[Table 4]

[0080]

[Table 5]

It is apparent that by performing the score processing under the conditions according to the present invention, it is possible to form a desirable score which is excellent in the lid opening property and does not generate a large "burr" which is not desirable for safety on the fractured surface. A three-piece can with a lid having a score formed under the conditions of the present invention was manufactured, filled with water, heated to generate an internal pressure of about 2 bar, and the pressure resistance was evaluated. It was confirmed that those manufactured by the above method had the same pressure resistance as those obtained by the conventional score forming method. Also, the sample can prepared in the same manner was dropped on a concrete surface from a height of 1.5 mm, and the impact resistance characteristics of the score portion were investigated.The score portion manufactured under the conditions of the present invention was manufactured by a conventional method. It was found that the score portion had substantially the same impact resistance.

Example 4 As materials, steel A --- C: 0.0018 wt%, Si: 0.01 wt%, Mn: 0.50 wt
%, P: 0.004 wt%, Al: 0.055 wt%, S: 0.007 wt%
%, N: 0.0095 wt% and Nb: 0.005 wt%, the balance being substantially Fe composition Steel B --- C: 0.0018 wt%, Si: 0.01 wt%, Mn: 0.50 wt%
%, P: 0.004 wt%, Al: 0.055 wt%, S: 0.007 wt%
%, N: 0.0095 wt%, Ti: 0.008 wt% and B: 0.0005
A steel slab containing wt% and the balance substantially consisting of Fe was used under the following conditions: • Slab heating temperature: 1250 ° C • Finish rolling temperature: 890 ° C • Finish thickness: 2.3 mm • Primary cold rolling Rate: 90% ・ Annealing: continuous annealing (750 ° C-20s without overaging) ・ Secondary cold rolling reduction rate: Cold rolled steel sheet (thickness: 0.20mm) manufactured with 10% (skin pass) and weight per unit area: A tin plate having a hardness of 60 and having a Sn plating of 6.5 g / m ² was used. A SOT (Stay-on-tab) lid having a diameter of 202 (approximately 54.0 mmφ) was manufactured using the above-mentioned respective steel sheets under the conditions shown in Table 6, and various characteristics were investigated. The score forming method was compared between the conventional method and the method according to the present invention. At this time, the score remaining thickness, which is considered to have the greatest effect on the opening property, was set to be equal. In addition, No. 1 was heat-softened at 240 ° C. for 0.5 min.
Table 6 also shows the results obtained by investigating the opening properties, opening safety, and rust resistance when the thus obtained open end score is opened.

[0083]

[Table 6]

As is clear from the table, each of the open ends obtained according to the present invention has a score part opening property,
The opening safety and rust resistance were all excellent.

Example 5 A steel sheet was prepared by using the same steel sheet as the steel A of Example 4 as a material and plating 100 mg / m ^{2 of} metal Cr and 20 mg / m ^{2 of} Cr oxide as surface treatments. A film-laminated steel sheet was manufactured by heat-sealing a PET film having a thickness of 20 μm thereon. Then, score processing was performed under the conditions shown in Table 7, and the openability, the safety of the opening and the rust resistance were examined in the same manner as in Example 4. The results obtained are also shown in Table 7.

[0086]

[Table 7]

As is clear from the table, each of the open ends obtained according to the present invention has a score part opening property,
The opening safety and rust resistance were all excellent.

[0088]

As described above, according to the present invention, it is possible to easily and inexpensively obtain an open end which is excellent not only in the openability of the score portion and the safety of the open portion but also in the rust resistance. In particular, the present invention provides an easy-open can lid without the need for extra repair painting, which has conventionally been a problem when iron is used in place of a can lid material that has been often manufactured from aluminum material. It can be manufactured, and since this easy-open can lid does not produce a sharp "burr" as in the past when opening,
There is a great advantage in that the danger of incising the hand, finger, mouth, etc. at that portion is extremely small, that is, the safety is extremely high.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a pre-shearing process has been performed on a material steel plate.

FIG. 2 is a diagram showing a state in which a return shearing process from the opposite direction is added after a preliminary shearing process.

FIG. 3 is a diagram showing a brittle state of a material steel sheet after pre-shearing and then back shearing.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C22C 38/14 C22C 38/14 C23C 2/04 C23C 2/04 // C21D 9/46 C21D 9/46 H (72) Inventor Takashi Ohara 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Co., Ltd. Hironobu Ohno 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Kawasaki Steel Corporation Chiba Works

Claims (28)

[Claims] 1. An open end of an easy-open can, wherein a score portion of the open end is formed by preliminary shearing in one direction and returning shearing in a reverse direction. Open end with excellent safety and opening safety. 2. The open end according to claim 1, wherein the pre-shearing amount in one direction is 10 to 50% of the plate thickness, and the open end is excellent in lid opening property and opening safety. 3. The method according to claim 1, wherein the shear fracture portion caused by the pre-shearing and the return shearing is 30 to 90% of the sheet thickness.
An open end with excellent lid opening and opening safety. 4. The open end according to claim 1, wherein the score portion has been subjected to a pre-shearing process and a return shearing process and then subjected to a heat softening treatment, wherein the open end is excellent in lid opening property and opening safety. 5. The open end according to claim 1, wherein the material of the easy-open can is a cold-rolled steel plate, wherein the open end is excellent in lid opening property and opening safety. 6. The cold-rolled steel sheet as the material of the easy-open can according to claim 5, wherein: C: 0.1 wt% or less, Si: 0.30 wt% or less, Mn: 1.00 wt% or less, Al: 0.005 to 0.20 wt%. , N: 0.020 wt% or less, with the balance being substantially Fe.
Open end with excellent lid opening and opening safety. 7. The cold-rolled steel sheet as the material of the easy-open can according to claim 5, wherein: C: 0.1 wt% or less, Si: 0.30 wt% or less, Mn: 1.00 wt% or less, Al: 0.005 to 0.20 wt%. , N: 0.020 wt% or less, Nb: 0.003 to 0.02 wt%, Ti: 0.003 to 0.02 wt%, B: 0.0005 to 0.004 wt%, and one or more selected from the group consisting of: The remainder is essentially an Fe composition, an open end with excellent lid opening and opening safety. 8. The lid openability, opening safety and score according to claim 5, 6 or 7, wherein the cold-rolled steel sheet as the material of the easy-open can has a surface treatment layer on its surface. Open end with excellent rust resistance in the processed part. 9. The cover opening property, opening safety and score according to claim 8, wherein the surface treatment layer is composed of one or more of a metal plating layer and an organic resin coating layer or a composite layer of both. Open end with excellent rust resistance in the processed part. 10. The open end according to claim 9, wherein the surface treatment layer is a Sn plating layer, wherein the open end is excellent in lid opening property, opening safety, and rust resistance of the score-processed portion. 11. The open end according to claim 10, wherein the surface end of the ground iron has a diffusion layer of Ni, which is excellent in lid opening properties, opening safety, and rust resistance of the score processing portion. 12. The open end according to claim 9, wherein the surface treatment layer is a Cr plating layer, wherein the open end is excellent in lid opening property, opening safety, and rust resistance of the score-processed portion. 13. The method according to claim 5, wherein
An open end with excellent lid opening and opening safety, characterized by having a decarburized layer on the surface of the ground iron. 14. The method according to claim 1, wherein
An open end made of a work-hardened metal plate with excellent lid opening and opening safety. 15. A method for manufacturing an open end of an easy-open can, in which a score is formed on the open end, a preliminary shearing process is first performed on a score processing assumed portion from one direction, and then a return process is performed from the opposite direction. An open-end manufacturing method characterized by performing a shearing process and having excellent lid opening properties and opening safety. 16. The method for manufacturing an open end according to claim 15, wherein the amount of preliminary shearing is 10 to 50% of the plate thickness, and which is excellent in lid opening property and opening safety. 17. The method for manufacturing an open end according to claim 15, wherein the shear fracture portion caused by the pre-shearing process and the back shearing process is 30 to 90% of the plate thickness, and which is excellent in lid opening property and opening safety. . 18. The method for manufacturing an open end according to claim 15, 16 or 17, wherein the material of the easy-open can is a cold-rolled steel sheet, and the open end is excellent in lid opening property and opening safety. 19. The cold-rolled steel sheet as the material of the easy-open can according to claim 18, wherein: C: 0.1 wt% or less, Si: 0.30 wt% or less, Mn: 1.00 wt% or less, Al: 0.005 to 0.20 wt%. , N: 0.020 wt% or less, with the balance being substantially Fe.
An open-end manufacturing method with excellent lid opening and opening safety. 20. The cold-rolled steel sheet as the material of the easy-open can according to claim 18, wherein: C: 0.1 wt% or less, Si: 0.30 wt% or less, Mn: 1.00 wt% or less, Al: 0.005 to 0.20 wt%. , N: not more than 0.020 wt%, Nb: 0.003 to 0.02 wt%, Ti: 0.003 to 0.02 wt%, B: 0.0005 to 0.004 wt%, and one or more selected from the group consisting of: The remainder is substantially a composition of Fe. An open-end manufacturing method excellent in lid opening property and opening safety. 21. The openability, safety and score of a cold rolled steel sheet according to claim 18, 19, or 20, wherein the cold rolled steel sheet as a material of the easy open can has a surface treatment layer on a surface thereof. An open-end manufacturing method with excellent rust resistance in the processed part. 22. The method according to claim 21, wherein the surface treatment layer comprises:
An open-end manufacturing method comprising a metal plating layer and an organic resin coating layer, which is a single layer or a plurality of layers or a composite layer of both, and is excellent in lid opening property, opening safety, and rust resistance of a score-processed portion. 23. The steel sheet according to any one of claims 18 to 22, wherein the steel sheet is 150 to 25 at or after the processing of the score portion.
An open-end manufacturing method characterized by heating to 0 ° C., which is excellent in lid opening property, opening safety, and rust resistance of a scored portion. 24. The method according to claim 23, wherein when the surface treatment layer includes an organic resin coating layer, the heating temperature is equal to or higher than the glass transition point of the organic resin. An open-end manufacturing method with excellent rust resistance in the score processing section. 25. The method according to claim 23, wherein the surface treatment layer comprises Sn.
A method for producing an open end which is excellent in lid opening property, safety of an opening, and rust resistance of a score-processed portion, wherein a heating temperature is equal to or higher than a melting point of Sn when the plating layer is used. 26. An openable lid according to claim 22, wherein the surface treatment layer is a Sn plating layer, or in claim 25, a Ni diffusion layer is previously formed on the surface of the base iron. Open-end manufacturing method with excellent opening and opening safety and rust resistance of the score processing part. 27. The openability, opening safety and score processing section according to claim 18, wherein annealing of the cold rolled steel sheet as a material after cold rolling is omitted. Open-end manufacturing method with excellent rust resistance. 28. The method according to claim 18, wherein in the annealing step of the cold-rolled steel sheet as a material, 5 ppm or more of decarburization is performed. Open-end manufacturing method.