JP2011056530A - Method for multi-statge molding of deep-drawn steel square can; deep-drawn steel square can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for multi-stage molding of a deep-drawn steel can having excellent surface property and to provide a deep-drawn steel can. <P>SOLUTION: The method for multi-stage molding does not substantially include an ironing step in all the drawing steps other than at least the final drawing step after a first drawing step, wherein the maximum value ΔHmax of an increment of the height of a drawn can at every position from the long side of the drawn can to the short side thereof is set at ≤40% in a second drawing step and a variation width of ΔH at every position is ≤20%, and a shape of a blank 10, a contour 2 of a punch per drawing step and a contour 1 of a dice are set so that ΔHmax is ≤25% and the variation width is ≤15% in all the drawing steps after the third drawing step. Thus, drawing is conducted without ironing processing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a cold drawn steel sheet, a deep drawn square can for batteries made of surface-treated steel sheets such as Ni plating, and other deep drawn square cans, and the surface properties of the deep drawn square can wall surface without ironing marks (galling marks). The present invention relates to a deep-drawn square can excellent in a multi-stage press-molding method for deep-drawn square cans and a press-molding method having a long die life without performing ironing.

  Battery square cans made of cold-rolled steel sheets, surface-treated steel sheets such as Ni plating, and other square cans with deep can depth are formed by a multistage press molding method. In multi-stage presses for square cans such as battery cans, the can corner of the product will flow into the corner with a high squeezing rate toward the small can corner R, and the can height at the corner of the can can be pressed. Each time it is squeezed, it becomes significantly higher. On the other hand, there is almost no drawing molding in the long side portion or the straight side portion of the short side portion, and only the die shoulder R portion flows in, so the increase in the can height is negligible. When such molding is repeated in multiple stages, a large difference occurs in the metal flow between the corner portion and the straight side portion, making it difficult for the steel plate to flow into the corner portion, and press fracture may occur.

  Conventionally, multi-stage press molding of square cans with a deep can like battery square cans compensates for the difference in the amount of inflow between the above-mentioned corner and right side steel plates. An ironing press method for preventing press cracking by performing thinning and ironing is performed. For example, in [Effects of the invention] of Patent Document 1, “because the thickness in the vicinity of the corner is reduced so that a uniform thickness can be obtained in each downstream corner drawing process, (Omitted) It becomes possible to obtain a uniform thickness by suppressing the uneven thickness phenomenon that tends to occur in the corner drawing, and the die manufacturing cost is reduced and the die adjustment cost including maintenance is reduced. ing.

  However, since this ironing press molding method performs ironing, the steel sheet slides with a very high compression surface pressure applied to the ironing surface of the die, and the wear of the die increases and the die life is increased. If the press speed is increased in order to improve the productivity, heat generation increases and troubles such as seizure tend to occur. Further, the wall surface on which the ironing process of the product has been performed has a minute screed shape due to ironing marks (scratching marks), that is, sliding marks during the ironing process. For example, in the case of a battery can, a Ni-plated steel plate is used for corrosion resistance, etc., but a sliding trace is generated on the Ni-plated surface, and the effective Ni-plated layer is thinned by forming a fine screed shape. The surface is exposed and the corrosion resistance is lowered. Therefore, there is a problem that it is necessary to increase the plating thickness in order to ensure the predetermined corrosion resistance.

  In addition, although we investigated the conventional technology related to the multi-stage press molding method for battery square cans made of surface-treated steel sheets such as cold-rolled steel sheets and Ni plating, about the molding methods that can perform predetermined press molding without performing ironing I didn't find it.

Japanese Patent No. 3160755

  The problem to be solved by the present invention is that, in a deep drawn square can such as a deep drawn square can for a battery made of a cold-treated steel sheet or a surface-treated steel sheet such as Ni plating, It is to provide a multi-stage press molding method for deep-drawn square cans and deep-drawn iron square cans having excellent surface properties without any traces.

  The present inventors have studied the provision of a deep-drawn square can excellent in surface properties having no ironing traces (galling marks) on the wall of the deep-drawn square can and its molding method, and completed the present invention. The gist is as follows.

(1) A multi-stage press molding method for deep-drawn iron square cans, wherein in all the drawing processes after the first drawing process, at least a drawing process other than the final drawing process is substantially not subjected to ironing, Height increase rate of the squeezed can at each position from the long side to the short side of the squeezed can in the second squeezing step (ΔH (%) = (can height after squeezing−can height before squeezing) / can before squeezing The maximum value ΔHmax of height × 100) is 40% or less, and the variation range of ΔH (ΔHmax−ΔHmin) at each position is 20% or less, and ΔHmax is 25% in all drawing processes after the third drawing process. Hereinafter, by setting the blank shape, the drawing punch contour for each drawing process, and the die profile so that ΔHmax−ΔHmin is 15% or less, it is possible to perform drawing without performing ironing. Deep drawn iron square can Stage press molding method.
(2) The simulation according to FEM numerical analysis is repeatedly performed, and the blank shape and the drawing punch and die outline for each drawing process are set in consideration of the workability and anisotropy of the steel sheet used. Multi-stage press molding method for drawn iron square cans.
(3) A deep-drawn iron square can press-molded by the multistage press-molding method according to (1) or (2).

  The deep-drawn square can of the present invention and the molding method thereof are ironed on the wall of a deep-drawn square can in a deep-drawn square can such as a deep-drawn square can for a battery made of a cold-treated steel sheet or a surface-treated steel sheet such as Ni plating. The present invention provides a deep drawing square can excellent in surface properties having no traces (scratch marks) and a multistage press molding method for deep drawing iron square cans without the above-mentioned problems of conventional ironing press molding methods. The problem is that “wearing of the mold becomes large and the life of the mold becomes extremely short”, and “the higher the press speed in order to improve productivity, the more heat is generated and the seizure occurs. Furthermore, “the wall surface on which the ironing process of the product has been performed has a sliding trace and becomes a fine crease shape. For example, in the case of a battery can, a Ni-plated steel sheet is used for corrosion resistance and the like. , That N Sliding traces are generated on the plated surface, and the effective Ni plating layer becomes thin when the effective Ni plating layer is thinned. When the iron surface is exposed and the corrosion resistance is lowered, it is necessary to increase the plating thickness in order to ensure the predetermined corrosion resistance. Such as “There are issues such as”.

It is a figure which shows the typical example of the deep drawing square can of this invention, (a) is a top view, (b) is a front view. It is a top view which shows the representative example of the blank of this invention. It is the top view and sectional drawing which show the example of the press metal mold | die of the 1st process-3rd process of this invention. FIG. 4 is a perspective view showing the first and third step drawn cans molded according to FIG. 3. It is a graph which shows (DELTA) H distribution of the 2nd process of the square can made as an experiment by FIG. It is a graph which shows (DELTA) H distribution of the 3rd process of the square can made as an experiment by FIG.

  The present invention is described in detail below.

  The present inventors firstly made a large square battery having a can inner width W = 85 mm, a can inner thickness T = 15 mm, a can height H = 45 mm, a can inner corner radius Rc = 1.0 mm, and a plate thickness t = 0.40 mm. For the can (see FIG. 1), the punch and die clearance in the entire drawing process was made larger than the thickness of the side wall plate before molding, and trial production was attempted by a multi-stage press molding method of a deep drawn iron square can that is not ironed. The first trial was made with a seven-step drawing plan, and cracks occurred when the third step was drawn. The second trial was increased in the number of processes, and the trial was made with a nine-step drawing plan. did. After that, the shape of the punch mold was corrected and trial manufacture was carried out. In either case, cracks occurred at the boundary between the corner part and the right side part, and drawing was not possible.

  The present inventors examined in detail why a crack occurred at the boundary between the corner portion and the right side portion during the intermediate process, and the drawing process could not be performed. As an approximate molding of the corner portion of the square can, a round can in which four corner portions are collected, that is, in the case of this prototype square can, Rc = 1.0 mm and the can height H = 45 mm. 2.0 mm) × (H = 45 mm), which is extremely severe deep drawing compared to an AA battery can (about 13.5φ × about 50.0 H). Therefore, it was found that the point of molding was how to smoothly flow the steel plate in the vicinity of the corner part to the straight side part, and various studies were made using the molding simulation (FEM analysis). As a result, the rate of increase in the height of the can in each position from the long side to the short side of the drawn can in the second drawing step (ΔH (%) = (can height after drawing−can before drawing) The maximum value (ΔHmax) of height) / can height before squeezing × 100) is 40% or less, the variation range of ΔH (ΔHmax−ΔHmin) at each position is 20% or less, and the third squeezing step In all subsequent drawing processes, set the blank shape, the drawing punch outline for each drawing process, and the die outline so that ΔHmax is 25% or less and ΔHmax−ΔHmin is 15% or less. By using the basic design philosophy of mold design, that is, the blank shape and the criteria for determining the quality of the mold design for each process, it is possible to perform drawing without ironing, and deep drawing square cans without ironing The most important mold design to achieve press molding Was knowledge that it is a point. The deep-drawn square can molded in this way has no ironing marks on the wall surface of the can, so there is no ironing marks on the wall surface of the press can. It becomes a can.

  Even if only the molding simulation is used without having the design concept of the present invention, if any one of the steel plate characteristics, the lubrication characteristics, the blank shape, and the mold shape of each process is changed, the moldability is determined. Since the shape of the drawn product and the molding status of each process (wrinkles, cracks, can wall height and ear shape, plate thickness distribution) all change, it is very much to derive molding conditions to obtain good results There are combinations of molding conditions, which are extremely difficult.

  Embodiments of the present invention will be described below with reference to the drawings.

  The rectangular can molded according to the present invention is, for example, a rectangular battery can having a small can corner R dimension Rc and a deep can depth H as shown in FIG. A typical example is a square can for a Li square battery. The effect of the present invention can be exhibited when H / Rc ≧ 15, and the effect is particularly remarkable when applied to a square can with H / Rc ≧ 25. In addition, the deep-drawn square can made by applying the present invention has a finished depth after it has been subjected to trimming processing to correct the can height, shape correction of the wall surface, drilling processing, etc. It becomes an aperture-angle battery can or a deep-angle-angle container can.

  The embodiment of the present invention will be specifically described with reference to FIGS. FIG. 1 shows a square can 11 in which the height of a deep-drawn square can made according to the present invention is trimmed to H = 43.0 mm, (a) is a plan view seen from above, and (b) is a front view. is there.

  2 to 4 show the process of press-molding the square can of FIG. 1 by the molding method of the present invention, FIG. 2 shows the shape of the blank 10, and FIG. 3 shows the first drawing process to the third (final) drawing. The shape of punch P, die D, and wrinkle presser (blank holder) BH in the process, FIG. 4 shows the appearance of the drawn cans in the first to third steps. In FIG. 3, 1 is the outline of the die D, 2 is the outline of the punch P, 3 is the outline of the bottom of the punch P, 4 is the outer holder outline of the can before drawing, and 5 is the outline of the inner holder of the can before drawing. The outer holder contour 4 of the can before drawing is integrated with the die D, and the inner holder contour 5 of the can before drawing is integrated with the wrinkle retainer BH. The squeezed cans (11a, 11b, 11c) of the first step to the final third step are free from cracks, necking, and wrinkles near the corners, and a good squeezed can is obtained.

  5 and 6 show the maximum value of the height increase rate ΔH of the squeezed can at each position from the long side to the short side of the squeezed can in the second squeezing step of the prototype deep-drawn square can. Whether ΔHmax is 40% or less, ΔH fluctuation range (ΔHmax−ΔHmin) at each position is 20% or less, and ΔHmax is 25% or less and ΔHmax−ΔHmin is 15% or less in the third drawing step. It has been investigated. As shown in FIG. 5, ΔHmax = 34% of the second-stage drawn can, ΔHmax−ΔHmin = 34% −18% = 16%, and as shown in FIG. 6, ΔHmax = 17% of the third-stage drawn can , ΔHmax−ΔHmin = 17% −8% = 9%, which is molded within the scope of the present invention, and is a three-stage multi-stage press molding method that does not perform ironing. As a result, a good squeezed can was obtained.

Note that ΔH shown in FIG. 5 and FIG. 6 is a method in which the FEM numerical analysis is not used, the position number is marked on the upper end of the can wall before the second drawing process, for example, at a pitch of 2 mm, and from the bottom of the can for each position number. The vertical height of the can wall is measured as H1, and the vertical height of the can wall from the bottom of each position number after the second drawing is measured as H2,
ΔH (%) = (H2−H1) / H1 × 100
And ΔH after the third squeezing step can be similarly calculated and obtained. Moreover, what is necessary is just to obtain | require the can height increase rate (DELTA) H (%) for every mode number (mesh number) of the can upper end part at the time of FEM analysis.

  As described above, using a quantitative index of ΔH, and setting the blank shape, the drawing punch outline for each drawing process, and the die outline with the specific numerical regulation of the present invention, It is possible to perform drawing without performing ironing.

  The resulting deep-drawn square cans can be manufactured into deep-drawn iron square cans with excellent surface properties without any press-molded can wall markings (galling marks). The deep-drawn square can that was press-molded without performing good corrosion resistance.

  Steel plates used in the deep drawn square can of the present invention are cold-rolled steel plates, Ni-plated or Ni-Sn alloy-plated steel plates, surface-treated steel plates such as resin film-coated steel plates, and iron-based steel plates (stainless steel). Can also be effective.

  The present invention can be applied to a method of press-molding a square can made of various steel plates.

1 Die outline 2 Punch outline 3 Punch bottom outline 4 Outer holder outline of can before drawing 5 Inner holder outline of can before drawing P Punch D Die BH Wrinkle presser

Claims (3)

A multi-stage press molding method for deep-drawn iron square cans,
In all drawing processes after the first drawing process, at least a drawing process other than the final drawing process is a multistage molding method that does not substantially perform ironing,
Height increase rate of the squeezed can at each position from the long side to the short side of the squeezed can in the second squeezing step (ΔH (%) = (can height after squeezing−can height before squeezing) / can before squeezing The maximum value ΔHmax of height × 100) is 40% or less, and the variation range of ΔH (ΔHmax−ΔHmin) at each position is 20% or less, and ΔHmax is 25% in all drawing processes after the third drawing process. Hereinafter, by setting the blank shape, the drawing punch contour for each drawing process, and the die profile so that ΔHmax−ΔHmin is 15% or less, it is possible to perform drawing without performing ironing. Multi-stage press molding method for deep drawing iron square cans.   The deep drawn iron angle according to claim 1, wherein simulation by FEM numerical analysis is repeatedly performed, and the blank shape and the drawing punch and die outline for each drawing process are set in consideration of workability and anisotropy of the steel sheet used. Multi-stage press molding method for cans.   A deep-drawn iron square can press-molded by the multistage press-molding method according to claim 1 or 2.