Cylindrical deep drawing processing method

Abstract

To suppress the height of an ear formed at the edge of a finished article in a circumferential direction of the edge, in the finished article manufactured through cylindrical deep drawing processing of a metal plate.SOLUTION: A die used for cylindrical deep drawing processing of a metal plate is provided with a die shoulder having a shoulder radius represented by a prescribed cos function. This cylindrical deep drawing processing method measures a Lankford value in a plurality of directions included in a two-dimensional plane along the surface of a metal plate for the metal plate before processing. Then, the metal plate is installed on the die so that a direction indicating a minimum Lankford value can be along an angle position θD equivalent to a maximum value RDmax of the die shoulder or a direction indicating a maximum Lankford value can be along an angle position θD equivalent to a minimum value RDmin of the die shoulder.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for deep drawing a cylindrical metal sheet. [Background technology]

[0002] In the cylindrical deep drawing process, unevenness called ears is generated on the edge of the cup-shaped workpiece due to the anisotropy of the metal plate material. The final product is obtained by trimming the ears of the workpiece, but it is preferable that the height of the ears is small. In order to solve this problem, the technology described below has been proposed.

[0003] Patent Document 1 discloses a method for producing a steel sheet for drawn pipes with little earing by using a steel slab having a predetermined composition and subjecting it to hot rolling, cold rolling, annealing, and cold rolling again.

[0004] Patent document 2 discloses a cylindrical deep drawing die in which the die shoulder is composed of a small radius portion (shoulder radius of 0.3 to 1.0 mm), a large radius portion (shoulder radius of 0.5 to 3.0 mm), and a transition portion (shoulder radius between the small radius portion and the large radius portion), and the value of (large radius portion die shoulder radius) / (small radius portion die shoulder radius) is 1.3 to 6.0.

[0005] Patent document 3 discloses a metal sheet for deep drawing of a cylinder, in which convex portions of predetermined dimensions are continuously and uniformly distributed in one or more directions on the surface of the metal sheet for deep drawing of a cylinder, and the area ratio of the convex portions is 20% or more and 60% or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2-141536 [Patent Document 2] Japanese Patent Application Publication No. 5-050152 [Patent Document 3] Japanese Patent Application Publication No. 7-328727 Summary of the Invention [Problem to be solved by the invention]

[0007] The invention described in Patent Document 1 is a method for manufacturing a steel sheet before drawing, and the invention described in Patent Document 3 is a metal sheet for cylindrical deep drawing before drawing, so they do not focus on the device performing the drawing to suppress the occurrence of ears.

[0008] According to the invention described in Patent Document 2, the degree of peaks and valleys formed on the edge of the processed product (ear ratio) is reduced by focusing on the shoulder radius of the die, but there is room for improvement. That is, in Patent Document 2, the shoulder radius is constant in both the small radius portion and the large radius portion, so it is not possible to reduce the ear ratio depending on the position within the small radius portion or the position within the large radius portion. [Means for solving the problem]

[0009] In the cylindrical deep drawing method of the present invention, a die used in cylindrical deep drawing of a metal sheet is provided with a die shoulder having a shoulder radius represented by the following formula (I).

[0010]

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[0011] In the above formula (I), R D is the shoulder radius [mm], θ D is the angular position in the circumferential direction of the die [deg], R Dmax is the shoulder radius R D Maximum value of [mm], R Dmin is the shoulder radius R D is the minimum value [mm], and f is the shape factor [-].

[0012] In the cylindrical deep drawing method, the Lankford values ​​of a metal sheet before processing are measured in multiple directions contained in a two-dimensional plane along the surface of the metal sheet. The direction showing the smallest Lankford value is the maximum value R of the die shoulder. Dmax The angular position θ DOr, the direction showing the maximum Lankford value is along the minimum value R of the die shoulder. Dmin The angular position θ D A metal plate is placed on the die so that it fits along the

[0013] Angular position θ D Shoulder radius R according to D and the angular position θ when the metal plate is placed on the die. D The metal plate can be placed on the die such that the distribution of Lankford values ​​as a function of the temperature is reciprocal.

[0014] The added value expressed by the following formula (II) is the angular position θ D A metal plate can be placed on the die so that the melting point is constant regardless of

[0015]

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[0016] In the above formula (II), S is an additive value [-], R D (θ D ) is the angular position θ D Shoulder radius [mm] according to R Dave is multiple angular positions θ D Shoulder radius R D Average value of [mm], r(θ D ) is the angular position θ D Lankford value according to [-], r ave is multiple angular positions θ D The Lankford value r(θ D ) is the average value [-].

[0017] The added value expressed by the following formula (III) is the angular position θ D Regardless of this, the metal plate can be placed on the die so as to satisfy the condition shown in formula (IV) below.

[0018]

number

[0019] In the above formula (III), S is an additive value [-], R D (θ D ) is the angular position θ D Shoulder radius [mm] according to R Dave is multiple angular positions θ D Shoulder radius R D Average value of [mm], r(θ D ) is the angular position θ D Lankford value according to [-], r ave is multiple angular positions θ D The Lankford value r(θ D In the above formula (IV), S is the sum [-], S ref is the standard addition value [-].

[0020] Standard addition value S ref can be 1.5 or more and 3.0 or less. Also, the shape factor f shown in the above formula (I) can be 4. The clearance distance formed between the die hole of the die and the punch that enters the die hole during processing can be equal to or less than the thickness of the metal sheet before processing. Effect of the Invention

[0021] According to the present invention, by using a die equipped with a die shoulder having a shoulder radius expressed by the above formula (I) and by placing a metal plate in the die as described above, the height of the ear formed on the edge of the processed product can be reduced in the circumferential direction of the edge. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a schematic diagram showing the configuration of a deep drawing apparatus. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4A] 4 is a cross-sectional view taken along the line AA in FIG. [Figure 4B] 4 is a cross-sectional view taken along line BB in FIG. [Diagram 5]FIG. 13 is a diagram illustrating the angular position of the dice. [Figure 6] FIG. 13 is a diagram showing the relationship between the angular position and the shoulder radius in a die. [Figure 7] FIG. 2 is a diagram illustrating a number of directions in which the Lankford values ​​are different for a metal plate. [Figure 8] FIG. 13 is a diagram showing the relationship between Lankford value and shoulder radius as a function of angular position. [Figure 9] 1 is a photograph showing a processed product obtained in an example. [Figure 10] 1 is a photograph showing a processed product obtained in Comparative Example 1. [Figure 11] FIG. 2 is a perspective view of a die used in Comparative Example 1. [Figure 12] FIG. 2 is a plan view of a die used in Comparative Example 1. [Figure 13] 13 is a cross-sectional view taken along CC in FIG. 12. [Figure 14] 4 is a photograph showing a processed product obtained in Comparative Example 2. [Figure 15] FIG. 13 is a diagram illustrating a method for measuring the edge height of a processed product. [Figure 16] FIG. 1 is a diagram showing the measurement results of ear height for an example and comparative examples 1 and 2. [Figure 17] FIG. 4 is a diagram showing the measurement results of thickness deviation for an example and comparative examples 1 and 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (Deep drawing equipment) The configuration of the deep drawing apparatus will be described with reference to Fig. 1. The deep drawing apparatus 10 has a punch 11, a die 12, and a blank suppression plate 13. A metal sheet 14 to be deep drawn is placed on the upper surface of the die 12, and the blank suppression plate 13 is disposed on the upper surface of the metal sheet 14. As a result, when deep drawing is performed, the metal sheet 14 is sandwiched between the die 12 and the blank suppression plate 13. The metal sheet 14 is formed in a disk shape and has a diameter D B has.

[0024] Punch 11 has a diameter of DP The blank suppression plate 13 has a through hole 13a through which the punch 11 passes. The die 12 has a die hole 12a through which the punch 11 enters. The die hole 12a has a diameter D D The diameter D of the die hole 12a is D is the diameter D of punch 11 P When the punch 11 enters the die hole 12a, a clearance is formed between the punch 11 and the die hole 12a. Here, the clearance distance (hereinafter, referred to as "clearance distance") c is "(D D -D P ) / 2".

[0025] The clearance distance c can be set to be equal to or less than the thickness (hereinafter referred to as the "initial thickness") t0 of the metal sheet 14 before processing. This allows the metal sheet 14 to be ironed, making it easier to suppress variations in thickness of the processed product. Here, it is preferable that the ratio c / t0 of the clearance distance c to the initial thickness t0 satisfies the condition shown in the following formula (1).

[0026]

number

[0027] By setting the ratio c / t0 to 1.0[-] or less, the ironing process can be performed. On the other hand, when the ratio c / t0 is less than 0.5[-], the clearance distance c becomes too small relative to the initial thickness t0, making it difficult to perform the ironing process. Therefore, it is preferable that the ratio c / t0 is 0.5[-] or more.

[0028] The die shoulder 12b of the die 12 has a shoulder radius R D The shoulder radius R D changes continuously in the circumferential direction of the die 12. Specifically, the shoulder radius R D is expressed by the following equation (2).

[0029]

number

[0030] In the above formula (2), R D is the shoulder radius [mm], θ D is the angular position of the die 12 in the circumferential direction [deg], R Dmax is the shoulder radius R D Maximum value of [mm], R Dmin is the shoulder radius R D The minimum value of [mm], f is the shape factor [-]. Angular position θ D is expressed as an angle from a reference position when a predetermined position in the circumferential direction of the die 12 is taken as a reference position. As can be seen from the above formula (2), the shoulder radius R D is the angular position θ D It changes depending on the maximum value R Dmax and the minimum value R Dmin can be appropriately determined depending on the size of the processed product.

[0031] Fig. 2 shows a perspective view of the die 12, and Fig. 3 shows a plan view of the die 12. Fig. 4A is a cross-sectional view taken along line AA in Fig. 3, and Fig. 4B is a cross-sectional view taken along line BB in Fig. 3. In the cross-section shown in Fig. 4A, the shoulder radius R DA is the minimum value R Dmin In the cross section shown in FIG. 4B, the shoulder radius R DB is the maximum value R Dmax Therefore, the shoulder radius R DB is the shoulder radius R DA Greater than.

[0032] Angular position θ D is the shoulder radius R as shown in Figure 5. D is the minimum value R Dmin The position where D In the example shown in FIG. 5, the angle position θ D FIG. 6 shows the die shoulder 12b at an angular position θ D and shoulder radius R D As shown in Figure 6, the shoulder radius R D is the minimum value R Dmin and maximum value R DmaxBetween the angular positions θ D The angular position θ shown in Fig. 6 changes periodically according to the D and shoulder radius R D The relationship is defined by the above formula (2), and the shape factor f is 4. Although the shape factor f of the die 12 shown in FIG. 2 is 4, the shape factor f can also be set to a value other than 4.

[0033] (Deep drawing method) Metal sheet 14 is placed between die 12 and blank holder 13, and punch 11 is moved downward to perform cylindrical deep drawing on metal sheet 14. When metal sheet 14 is placed in die 12, the orientation of metal sheet 14 relative to die 12 is determined taking into account the Lankford value r of metal sheet 14, as described below. Lankford value r is defined as the strain ε t Strain ε in the plate width direction relative to w The ratio (ε w / ε t ) and can be measured in accordance with the provisions of JIS Z2254.

[0034] Since the metal plate 14 is processed through a rolling process, the Lankford value r varies depending on a plurality of directions included in a two-dimensional plane along the surface of the metal plate 14. Here, the Lankford value r varies depending on the conditions of the rolling process and the material of the metal plate 14.

[0035] 7, when the center C of the metal plate 14 is used as a reference, the Lankford value r in direction D1 differs from the Lankford value r in direction D2, and the Lankford value r in direction D3 differs from the Lankford value r in direction D2. Here, the angle between directions D1 and D2 is 45 degrees, and the angle between directions D1 and D3 is 90 degrees. The Lankford values ​​r in directions D1 and D3 may be different or may be equal.

[0036] When performing cylindrical deep drawing, first, before placing the metal sheet 14 in the die 12, the Lankford values ​​r of the metal sheet 14 are measured in a plurality of directions (for example, directions D1 to D3 shown in FIG. 7). Based on the measurement results, the Lankford value showing the maximum value (hereinafter referred to as the "maximum Lankford value") r max and the minimum Lankford value (hereinafter referred to as the "minimum Lankford value") r min It is possible to grasp the Lankford value r in the circumferential direction of the metal sheet 14 based on the center C shown in Fig. 7. The Lankford value r may or may not change periodically. As described above, the distribution of the Lankford value r in the circumferential direction of the metal sheet 14 changes depending on the conditions of the rolling process and the material of the metal sheet 14.

[0037] Next, the minimum Lankford value r min The direction corresponding to the shoulder radius R D is the maximum value R Dmax The angular position θ D The metal plate 14 is placed against the die 12 so that the direction D2 shown in FIG. 7 corresponds to the minimum Lankford value r min In the case where the direction D2 is the maximum value R Dmax The angular position θ D (For example, in FIG. 5, θ D The metal plate 14 is placed against the die 12 so that the metal plate 14 is aligned along the direction of the radius R (=45). Dmax The angular position θ D Since there are 45, 135, 225, and 315 degrees, these angular positions θ D It is sufficient that the direction D2 is aligned along one of the directions.

[0038] Minimum Lankford value r min If the direction corresponding to the shoulder radius R is marked on the metal plate 14, the metal plate 14 can be easily placed on the die 12. The marking can be performed by using a known method. D is the maximum value R Dmax The angular position θ Dmay be marked on the die 12. This makes it easier to place the metal plate 14 on the die 12 by simply aligning the mark formed on the metal plate 14 with the mark formed on the die 12.

[0039] When the metal plate 14 is placed in the die 12, the metal plate 14 may be slightly misaligned from the desired orientation. min The direction corresponding to the shoulder radius R D is the maximum value R Dmax The angular position θ D In this way, a certain degree of deviation is permissible for the installation orientation of the metal plate 14 relative to the die 12, and within this permissible range, the height of the lug formed on the edge of the processed product can be controlled in the circumferential direction of the edge. The above-mentioned permissible range can be, for example, min and the shoulder radius R D is the maximum value R Dmax The angular position θ D The deviation from the direction can be ±5°.

[0040] On the other hand, the minimum Lankford value r min The direction corresponding to the maximum value R Dmax The angular position θ D Instead of installing the metal plate 14 along the direction of the maximum Lankford value r max The direction corresponding to is the minimum value R Dmin The angular position θ D The metal plate 14 can be installed along the direction of the maximum Lankford value r max The direction corresponding to the shoulder radius R D is the minimum value R Dmin The angular position θ D This makes it possible to easily place the metal plate 14 on the die 12.

[0041] As described above, by determining the orientation of the metal sheet 14, placing it in the die 12, and performing cylindrical deep drawing, the height of the ear formed on the edge of the processed product can be suppressed in the circumferential direction of the edge. Here, when the metal sheet 14 is placed in the die 12 as described above, the shoulder radius R D (θ D ) and the Lankford value r(θ D ) is shown in Figure 8. Figure 8 shows data obtained in the Examples described below.

[0042] In Fig. 8, the vertical axis represents the Lankford value r and the shoulder radius R D The horizontal axis represents the angular position θ of the die 12. D Here, the vertical axis shows the Lankford value r(θ D ) is the ratio (r / r ave ) [-], and this ratio is the average value of the Lankford value r in multiple directions r ave For each angular position θ D The Lankford value r(θ D ) is the ratio of the shoulder radius R D is the ratio (R D / R Dave ) [-], and this ratio is expressed as D Shoulder radius R D The average value of R Dave For each angular position θ D Shoulder radius R D (θ D ) ratio.

[0043] In Figure 8, the angle positions θ of 0, 45, and 90 degrees D The Lankford value (r / r ave As can be seen from Fig. 8, the distribution of Lankford value r and shoulder radius R D Specifically, the distribution of the shoulder radius R D The smallest value (angle position θ D Shoulder radius R when is 0.90 degrees D ) the Lankford value r is the largest, and the shoulder radius R DThe largest value (angle position θ D When the angle is 45 degrees, the shoulder radius R D ) the Lankford value r is smallest.

[0044] This gives the Lankford value r and the shoulder radius R D The sum of S(S=(r / r ave )+(R D / R Dave The distribution of D In other words, by determining the orientation of the metal sheet 14 relative to the die 12 so that the distribution of the added value S is flat, it is possible to suppress the height of the lug formed on the edge of the processed product when the metal sheet 14 is subjected to cylindrical deep drawing.

[0045] The distribution of the sum S does not need to be a completely flat distribution. ref It is acceptable if the value is within the tolerance range. The lower limit of the tolerance range is 0.5×S ref The upper limit is 1.5 × S ref The lower limit can be set to 0.9×S ref The upper limit is 1.1 × S ref It is preferable to set the reference addition value S ref It is preferable that the value is 1.5[-] or more and 3.0[-] or less. EXAMPLES

[0046] (Example) It is made of stainless steel SUS304, has a thickness t0 of 0.47 mm, and a diameter D B A disk-shaped metal plate 14 having a diameter of 60 mm was prepared, and the Lankford values ​​r of this metal plate 14 were measured in a plurality of directions.

[0047] Next, a deep drawing apparatus 10 having the specifications shown in Table 1 below was used to deep draw the metal plate 14 to manufacture a processed product. Here, the Lankford value r (ratio r / r ave ) and shoulder radius R D (Ratio RD / R Dave The metal plate 14 was placed against the die 12 so that the minimum Lankford value r min The direction corresponding to the shoulder radius R D is the maximum value R Dmax The angular position θ D (θ D A metal plate 14 was placed against the die 12 so that the metal plate 14 was aligned along the direction of the die 12 (angle θ=45°). Fig. 9 shows a photograph of the processed product produced in this example.

[0048] [Table 1]

[0049] Comparative Example 1 Using a deep drawing apparatus described later, a processed product was manufactured by deep drawing the same metal plate 14 as in the example. Fig. 10 shows a photograph of the processed product manufactured in this example.

[0050] 11 to 13 show the die 15 of the deep drawing apparatus used in this comparative example. Fig. 11 is a perspective view of the die 15, Fig. 12 is a plan view of the die 15, and Fig. 12 shows the die 15 at an angular position θ D Fig. 13 is a cross-sectional view taken along the line CC in Fig. 12. As shown in Figs. 11 to 13, the shoulder radius R D is constant over the entire circumference of the die 15. The specifications of the deep drawing device used in this comparative example are shown in Table 2 below.

[0051] [Table 2]

[0052] Comparative Example 2 Using a deep drawing apparatus 10 having the specifications shown in Table 1 above, a deep drawing process was performed on the same metal plate 14 as in the Example to produce a processed product. In this comparative example, the installation direction of the metal plate 14 relative to the die 12 is different from that of the Example. Specifically, the minimum Lankford value r minThe direction corresponding to the shoulder radius R D is the minimum value R Dmin The angular position θ D (θ D A metal plate 14 was placed against the die 12 so that the metal plate 14 was aligned along the direction of the die 12 (angle θ=0 degrees). Fig. 14 shows a photograph of the processed product produced in this comparative example.

[0053] (Ear height measurement) The edge height He was measured for the processed products obtained in the example and comparative examples 1 and 2. The edge height He is the distance between the lowest point H1 and the highest point H2 on the edge of the processed product formed in an uneven shape, as shown in Fig. 15, and the edge height He was measured using a vernier caliper. The measurement results of the edge height He are shown in Fig. 16.

[0054] In the embodiment, the edge height He was the smallest. In the comparative example 2, although the specifications of the deep drawing apparatus 10 were the same as those in the embodiment, the installation direction of the metal plate 14 was different from that in the embodiment, and therefore the edge height He was higher than that in the comparative example 1.

[0055] (Measurement of thickness deviation) The thickness deviation Δt [mm] was measured for the processed products obtained in the example and comparative examples 1 and 2. Specifically, a thickness measuring device (micrometer) was used to measure the thickness at 8 positions in the circumferential direction of the processed product at a height of 15 [mm] from the bottom surface of the processed product. The thickness deviation Δt is the difference between the thickness (maximum value) and the thickness (minimum value). The measurement results of the thickness deviation Δt are shown in FIG. 17.

[0056] In the embodiment, the thickness deviation Δt was the smallest. In the comparative example 2, although the specifications of the deep drawing apparatus 10 were the same as those in the embodiment, the thickness deviation Δt was larger than that in the comparative example 1 because the installation direction of the metal plate 14 was different from that in the embodiment. [Explanation of symbols]

[0057] 10: deep drawing device, 11: punch, 12: die, 12a: die hole, 13: wrinkle suppression plate, 13a: through hole, 14: metal plate

Claims

1. The die used in cylindrical deep drawing of a metal sheet has a die shoulder having a shoulder radius represented by the following formula (I), [0010] In the above formula (I), R Ｄ is the shoulder radius [mm], θ Ｄ is the angular position of the die in the circumferential direction [degrees], R Ｄｍaｘ is the shoulder radius R Ｄ Maximum value [mm], R Ｄｍｉｎ is the shoulder radius R Ｄ is the minimum value [mm], f is the shape factor [-], For the metal plate before processing, the Lankford values ​​are measured in a plurality of directions included in a two-dimensional plane along the surface of the metal plate; The direction showing the minimum Lankford value is the maximum value R of the die shoulder. Ｄｍaｘ The angular position θ Ｄ or the direction showing the maximum Lankford value is along the minimum value R of the die shoulder. Ｄｍｉｎ The angular position θ Ｄ A cylindrical deep drawing method, comprising: placing a metal plate in the die so that the metal plate conforms to the die.

2. The angular position θ Ｄ The shoulder radius R Ｄ and the angular position θ when the metal plate is placed on the die. Ｄ 2. The method for deep drawing a cylinder according to claim 1, characterized in that the distribution of Lankford values ​​according to the drawing has a reciprocal relationship with each other.

3. When the metal plate is placed on the die, the added value expressed by the following formula (II) is Ｄ 2. The method for deep drawing a cylindrical body according to claim 1, wherein the drawing is constant regardless of the drawing speed. [0025] In the above formula (II), S is the added value [-], R Ｄ (θ Ｄ ) is the angular position θ Ｄ Shoulder radius [mm] according to R Ｄａｖｅ is a plurality of the angular positions θ Ｄ The shoulder radius R Ｄ Average value of [mm], r (θ Ｄ ) is the angular position θ Ｄ Lankford value [-] according to r ａｖｅ is a plurality of the angular positions θ Ｄ The Lankford value r (θ Ｄ ) is the average value [-].

4. When the metal plate is placed on the die, the added value expressed by the following formula (III) is Ｄ The cylindrical deep drawing method according to claim 1, characterized in that the condition shown in the following formula (IV) is satisfied regardless of the above. [0030] In the above formula (III), S is the added value [-], R Ｄ (θ Ｄ ) is the angular position θ Ｄ Shoulder radius [mm] according to R Ｄａｖｅ is a plurality of the angular positions θ Ｄ The shoulder radius R Ｄ Average value of [mm], r (θ Ｄ ) is the angular position θ Ｄ Lankford value [-] according to r ａｖｅ is a plurality of the angular positions θ Ｄ The Lankford value r (θ Ｄ ) is the average value [-], In the above formula (IV), S is the added value [-], S ｒｅｆ is the reference addition value [-].

5. The reference sum value S ｒｅｆ The cylindrical deep drawing method according to claim 4, characterized in that is 1.5 or more and 3.0 or less.

6. 2. The method for deep drawing a cylinder according to claim 1, wherein the shape factor f is 4.

7. A cylindrical deep drawing method according to any one of claims 1 to 6, characterized in that a clearance distance formed between the die hole of the die and a punch that enters the die hole during processing is less than or equal to the thickness of the metal plate before processing.

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