Punching forming female die for steel rectangular thin-wall shell part

Abstract

The invention discloses a stamping forming female die for a steel rectangular thin-wall shell part. The working face of the stamping forming female die is arranged to be of a right-angle fillet structure with segment difference. The right-angle rounding structure with the segment difference comprises a segment difference face and a female die working face which are sequentially connected in the downward pressing direction of the male die. The upper corner of the segment difference surface is set as a circular bead R1, and the lower corner of the segment difference surface is set as a circular bead R2; the upper corner of the working surface of the female die is a variable-diameter fillet R3, and the lower corner of the working surface of the female die is a fillet R4; the two long edges of the working face of the stamping forming female die are arranged in a sectional mode, and the variable-diameter fillets R3 on the sections are different in radius. The problems that in the stamping forming process of the rectangular thin-wall shell, the bottom and the opening are unstable and wrinkled, the bottom cracks, demolding is not smooth and the like are effectively solved.

Description

Technical Field

[0001] The invention relates to a forming die, and more particularly to a stamping die for a steel rectangular thin-wall shell part. Background Art

[0002] Compared with cylindrical shells (cylindrical parts), square shell parts (box-shaped parts) are also widely used. Due to the existence of four edges and corners, and some square shells are rectangular with large differences in length, the material forming and processing is much more difficult than that of cylindrical shells.

[0003] Typical rectangular thin-walled shell parts, such as lithium battery square shell outer packaging parts or similar shell parts, are usually formed by a combination of multi-pass deep drawing and thinning deep drawing. The blank is gradually drawn from a nearly elliptical shape to a box-shaped part. Figure 1 As shown, the forming die adopts a common combination of a punch 1, a die 2, and a blank holder 3, and a bottom support plate may usually be added. The existing die 2 usually adopts a certain die entry inclination angle, and the inclination angle α is mostly between 20 and 30°. This die form is suitable for relatively thick aluminum shell materials. However, with the development of new energy vehicles, square shell lithium batteries are constantly seeking lightweight and low carbon, and steel square shells have become an important choice.

[0004] If a steel square shell is selected, the wall thickness will inevitably be greatly reduced, and the material properties are quite different from those of aluminum. The concave die with an inclination angle cannot meet the stamping requirements of thin-walled rectangular shells. During the forming process, when the material flows from the angled part to the working surface, it is very easy to become unstable and wrinkled, and it cannot be eliminated by the bottom support plate. At the same time, the four corners of the bottom are prone to cracking.

[0005] In existing patent applications, such as Chinese patent CN 113172158A, a drawing die, a combined drawing die and a drawing method for box-shaped parts are disclosed, including a deformed die section, a roller combined die section and a corrective die section arranged in sequence from top to bottom, that is, a rigid die and a roller combined die are used, which is conducive to reducing friction during the forming process. However, the die design and corresponding tooling are relatively complex, with high requirements for equipment, and it is difficult to place the blank holder. It is not suitable for the stamping production of rectangular thin-walled shells, especially parts with relatively small corner radius, and is prone to instability and wrinkling.

[0006] For example, Chinese patent CN 112692169B discloses a die for deep drawing of rolled differential thickness plate box-shaped parts, which includes a deep drawing die part and a hydraulic control part, and can obtain high-quality differential thickness plate box-shaped parts mainly by controlling the reasonable matching of the blank holding force applied to the thin and thick sides of the differential thickness plate. However, it does not involve the details of the die, and cannot control the instability, wrinkling and cracking of thin-walled shell forming.

[0007] For example, Chinese patent CN 215543792U discloses a cold reverse extrusion die for an aluminum alloy rectangular thin-walled shell, which includes an upper punch assembly and a lower concave die assembly capable of moving downward to close the mold and moving upward to open the mold, and is used for extrusion forming of an aluminum alloy square shell, but is not suitable for forming a rectangular thin-walled steel shell. Summary of the invention

[0008] In view of the defects existing in the prior art, the purpose of the present invention is to provide a stamping forming die for a steel rectangular thin-walled shell part, which can effectively solve the problems of instability and wrinkling of the bottom and mouth, bottom cracking, and poor demoulding during the stamping forming process of the rectangular thin-walled shell.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] A stamping die for a steel rectangular thin-walled shell part:

[0011] The working surface of the stamping die is configured as a right-angled rounded structure with a step difference;

[0012] The right-angle chamfered structure with step difference comprises a step difference surface and a die working surface which are sequentially connected along the pressing direction of the punch;

[0013] The upper corner of the step difference surface is set to a rounded corner R1, and the lower corner is set to a rounded corner R2;

[0014] The upper corner of the working surface of the die is set to a radiused corner R3, and the lower corner is set to a radiused corner R4;

[0015] The two long sides of the working surface of the stamping die are arranged in sections, and the variable diameter fillet R3 on each section is arranged with a different radius.

[0016] Preferably, the height H1 of the step surface is between 2 and 10 mm.

[0017] Preferably, the inner diameter D1 of the step difference surface is larger than the outer diameter d1 of the outer surface of the shell of the previous forming pass; and

[0018] D1=d1+k1, k1 ranges from 0 to 1 mm.

[0019] Preferably, the radius of the fillet R1 is between 3 and 5 mm.

[0020] Preferably, the radius of the fillet R2 = r2-k2;

[0021] r2 is the fillet radius of the outer surface corner of the shell in the previous forming pass, and k2 is 1 to 2 mm.

[0022] Preferably, the two long sides of the working surface of the stamping die are arranged in sections, specifically including:

[0023] A point a0 is provided at the midpoint of the long side of the working surface of the stamping die;

[0024] Symmetrical points a1 and a2 are respectively arranged on both sides of the point a0;

[0025] Point a3 and point a4 are disposed outside the point a1 and the point a2, and the point a3 and the point a4 are symmetrically disposed relative to the point a0; wherein,

[0026] The length of the line segment from the point a1 to the point a2 is A1=(AB) / 2;

[0027] The length of the line segment from the point a1 to the point a3 and from the point a2 to the point a4 is A2=A1 / 2;

[0028] In the formula, A is the length dimension of the working surface of the stamping die, and B is the width dimension of the working surface of the stamping die.

[0029] Preferably, the radius of the variable diameter fillet R3 outside the line segment from the point a3 to the point a4 is r30, where r30 is an initial setting value;

[0030] The radius of the variable diameter fillet R3 on the line segment from the point a1 to the point a2 = r31, r31 = k3*initial setting value, k3 takes a value of 1.5-2 mm;

[0031] The variable radius fillet R3 on the line segment from the point a1 to the point a3 and the line segment from the point a2 to the point a4 adopts a gradual fillet radius, that is, gradually decreasing from r31 to r30.

[0032] Preferably, the radius of the fillet R4 = k4*r31, and k4 is 2 to 3 mm.

[0033] The present invention provides a stamping die for a steel rectangular thin-walled shell part, which adopts a right-angle chamfered corner entry method with a step difference, and different entry corner radii are arranged in sections in the two long sides of the die. At the same time, the upper and lower fillets on the die working surface have a suitable size relationship. This can effectively improve the problems of instability and wrinkling of the bottom and mouth, bottom cracking, and poor demolding during the stamping process of the rectangular thin-walled shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the use status of the existing stamping forming die;

[0035] Figure 2 It is a schematic axial view of the punching die of the present invention;

[0036] Figure 3 It is a top view schematic diagram of the stamping forming die of the present invention;

[0037] Figure 4 It is a schematic diagram of the use status of the stamping forming die of the present invention. DETAILED DESCRIPTION

[0038] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0039] Combination Figures 2 to 4 As shown, the present invention provides a stamping die for a steel rectangular thin-walled shell part, which adopts a right-angle chamfered die entry method with a step difference, and different die entry fillet radii are arranged in sections in the two long sides of the die, and the upper and lower fillets on the die working surface have a suitable size relationship, which can effectively improve the instability and wrinkling of the bottom and mouth, bottom cracking, and poor demolding during the stamping process of the rectangular thin-walled shell. Specifically including:

[0040] The working surface of the stamping die 10 is configured as a right-angled rounded structure with a step difference.

[0041] The right-angle chamfered structure with step difference comprises a step difference surface 12 and a die working surface 13 which are sequentially connected along the pressing direction of the punch 11 .

[0042] The height H1 of the step surface 12 is between 2 mm and 10 mm.

[0043] The inner diameter D1 of the step surface 12 is greater than the outer diameter d1 of the outer surface of the shell of the previous forming pass; and

[0044] D1=d1+k1, k1 ranges from 0 to 1 mm.

[0045] The upper corner of the step surface 12 is set to be a rounded corner R1, and the lower corner is set to be a rounded corner R2.

[0046] The upper corner of the die working surface 13 is set as a radiused corner R3 (that is, the die entry corner of the die working surface), and the lower corner is set as a radiused corner R4.

[0047] The radius of the fillet R1 is between 3 and 5 mm.

[0048] The radius of fillet R2 = r2-k2;

[0049] r2 is the fillet radius of the outer surface corner of the shell in the previous forming pass, and k2 is 1 to 2 mm.

[0050] The two long sides of the working surface of the stamping die 10 are both arranged in sections, and the variable diameter fillet R3 on each section is arranged to have a different radius.

[0051] Recombination Figure 3As shown, A is the length dimension of the working surface of the stamping die 10, B is the width dimension of the working surface of the stamping die 10, and A>B.

[0052] Thus, the two long sides of the working surface of the stamping die 10 are arranged in sections, specifically including:

[0053] A point a0 is provided at the midpoint of the long side of the working surface of the press forming die 10 .

[0054] Symmetrical points a1 and a2 are respectively arranged on both sides of point a0.

[0055] Point a3 and point a4 are disposed outside point a1 and point a2, and point a3 and point a4 are also disposed symmetrically with respect to point a0.

[0056] Among them, the length of the line segment from point a1 to point a2 is A1=(AB) / 2;

[0057] The length of the line segment from point a1 to point a3 and from point a2 to point a4 is A2=A1 / 2.

[0058] Thus, the radius of the variable diameter fillet R3 outside the line segment from point a3 to point a4 = r30, where r30 is the initial setting value;

[0059] The radius of the variable diameter fillet R3 on the line segment from point a1 to point a2 = r31, r31 = k3*initial setting value, k3 takes a value of 1.5 to 2 mm;

[0060] The variable radius fillet R3 on the line segment from point a1 to point a3 and the line segment from point a2 to point a4 adopts a gradual fillet radius, that is, gradually decreasing from r31 to r30.

[0061] The radius of fillet R4 = k4*r31, and k4 is 2 to 3 mm.

[0062] Example

[0063] In this embodiment, for a rectangular thin-walled shell, the length, width and height are 154*88*80mm respectively, the four corners have a radius of R3.6mm, the bottom corner radius is R1mm, and the wall thickness is t0.30mm; the blank adopts an elliptical shape with a length and width of 310mm and 270mm respectively, and a thickness of t0.30mm; it is stretched and formed in 6 passes. Except for the first pass using the common male and female molds, the female molds of the other passes all adopt the female mold design of the present invention. The female mold of the third pass is:

[0064] 1) The height H1 of the step surface 12 is 6 mm; the outer diameter d1 of the outer surface of the second secondary shell is 203 mm in length and 148 mm in width at the center, and the fillet radius of the outer surface of the corner is R3.5 mm; the inner diameter D1 of the step surface 12 is 203.5 mm in length and 148.5 mm in width at the center; the radius of the fillet R1 is 4 mm; the radius of the fillet R2 is 2 mm;

[0065] 2) The length and width of the working surface of the stamping die 10 are A=184mm and B=120mm respectively, the length of the line segment from point a1 to point a2 is A1=32mm, the length of the line segment from point a1 to point a3 and the length of the line segment from point a2 to point a4 is A2=16mm, the radius of the variable diameter fillet R3 of the die on the line segment from point a1 to point a2 is r31=3.5mm, the radius of the variable diameter fillet R3 of the die outside the line segment from point a3 to point a4 is r30=2mm, and the radius of the variable diameter fillet R3 of the die on the line segment from point a1 to point a3 and the line segment from point a2 to point a4 adopts a gradual fillet radius, that is, it gradually decreases from r31=3.5mm to r30=2mm;

[0066] 3) The radius of the lower fillet R4 of the die working surface = 8.8mm.

[0067] In this way, the instability and wrinkling of the mouth and bottom and the cracking of the bottom during the steel shell forming process are well controlled by the die entry form of step difference plus right-angle chamfer. At the same time, the segmented arrangement of the working fillet of the die improves the uneven flow of materials on the long and short sides during the deep drawing of the rectangular thin-walled shell. The upper and lower fillet radius settings of the working surface effectively improve the problems of poor demolding of the thin-walled shell, and finally achieve high-quality forming processing of the shell.

[0068] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A stamping die for a steel rectangular thin-walled housing part, characterized in that: The working surface of the stamping die is configured as a right-angled rounded structure with a step difference; The right-angle chamfered structure with step difference comprises a step difference surface and a die working surface which are sequentially connected along the pressing direction of the punch; The upper corner of the step difference surface is set to a rounded corner R1, and the lower corner is set to a rounded corner R2; The upper corner of the working surface of the die is set to a radiused corner R3, and the lower corner is set to a radiused corner R4; The two long sides of the working surface of the stamping die are arranged in sections, and the variable diameter fillet R3 on each section is arranged with a different radius.

2. The stamping die for the steel rectangular thin-walled shell part according to claim 1, characterized in that: The height H1 of the step surface is between 2 and 10 mm.

3. The stamping die for the steel rectangular thin-walled shell part according to claim 1, characterized in that: The inner diameter D1 of the step difference surface is greater than the outer diameter d1 of the outer surface of the shell of the previous forming pass; and D1=d1+k1, k1 ranges from 0 to 1 mm.

4. The stamping die for the steel rectangular thin-walled shell part according to claim 1, characterized in that: The radius of the fillet R1 is between 3 and 5 mm.

5. The stamping die for the steel rectangular thin-walled housing part according to claim 4, characterized in that: The radius of the fillet R2 = r2-k2; r2 is the fillet radius of the outer surface corner of the shell in the previous forming pass, and k2 is 1 to 2 mm.

6. The stamping die for the steel rectangular thin-walled shell part according to claim 1, characterized in that: The two long sides of the working surface of the stamping die are arranged in sections, specifically including: A point a0 is provided at the midpoint of the long side of the working surface of the stamping die; Symmetrical points a1 and a2 are respectively arranged on both sides of the point a0; Point a3 and point a4 are disposed outside the point a1 and the point a2, and the point a3 and the point a4 are symmetrically disposed relative to the point a0; wherein, The length of the line segment from the point a1 to the point a2 is A1=(AB) / 2; The length of the line segment from the point a1 to the point a3 and from the point a2 to the point a4 is A2=A1 / 2; In the formula, A is the length dimension of the working surface of the stamping die, and B is the width dimension of the working surface of the stamping die.

7. The stamping die for the steel rectangular thin-walled housing part according to claim 6, characterized in that: The radius of the variable diameter fillet R3 outside the line segment from the point a3 to the point a4 = r30, where r30 is an initial setting value; The radius of the variable diameter fillet R3 on the line segment from the point a1 to the point a2 = r31, r31 = k3*initial setting value, k3 takes a value of 1.5-2 mm; The variable radius fillet R3 on the line segment from the point a1 to the point a3 and the line segment from the point a2 to the point a4 adopts a gradual fillet radius, that is, gradually decreasing from r31 to r30.

8. The stamping die for the steel rectangular thin-walled housing part according to claim 7, characterized in that: The radius of the fillet R4 = k4*r31, and the value of k4 is 2 to 3 mm.

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