A die structure for improving the forming height of a plate material hole

Abstract

The application discloses a die structure for improving forming height of plate material flanging, which comprises an upper die body, an upper die pressing plate, a flanging punch and a lower die body; the upper die pressing plate is arranged on the lower surface of the upper die body through a pressure source component; a pressing ring-shaped insert is arranged on one side of the working surface of the upper die pressing plate, and a ring-shaped insert gasket is arranged between the pressing ring-shaped insert and the upper die pressing plate; a lower die ring-shaped insert is arranged on one side of the working surface of the lower die body, and a lower ring-shaped insert gasket is arranged between the lower die ring-shaped insert and the lower die body; a flanging gap t1 between the flanging punch and the lower die ring-shaped insert is set as a negative plate thickness gap; the bottom of the flanging punch is provided with a chamfer R1, and the top of the lower die ring-shaped insert is provided with a chamfer R2. The application makes the flanging easy to realize, low in cost, obvious in effect and more uniform in wall thickness.

Description

Technical Field

[0001] This invention relates to sheet metal stamping dies, and more specifically, to a die structure for improving the height of sheet metal perforation forming. Background Technology

[0002] Driven by the strategies of safety, environmental protection, green and low-carbon development, the use of advanced materials such as high-strength steel plates and aluminum plates to replace the original low-strength steel can reduce the number of parts and reduce weight, thereby achieving the goals of high safety and lightweighting. As a result, the application rate has been increasing year by year in recent years.

[0003] Flanging is a typical feature of stamped parts in the automotive, aerospace, and construction machinery industries. Flanging can be used to increase the rigidity of parts or to enhance the connection strength with other parts. For example, automotive chassis suspension parts and seat side panels often exhibit flanging characteristics. However, compared to low-strength steel, high-strength steel plates and advanced materials such as aluminum plates often have reduced flanging capabilities, resulting in increased processing and manufacturing difficulties and a higher cracking rate.

[0004] Combination Figure 1 and Figure 2 As shown, the existing flanging die structure includes an upper die body 1, an upper die pressure plate 2, a flanging punch 3, and a lower die body 4. The upper die pressure plate 2 is provided with pressure by a nitrogen cylinder 5. The sheet metal 6 is pre-punched in the previous process. After punching, the sheet metal 6 is placed on the lower die body 4. The upper die pressure plate 2 is pressed down by the pressure of the nitrogen cylinder 5, and the flanging punch 3 moves down to complete the flanging.

[0005] In existing flanging die structures, the flanging gap 't' is equal to the plate thickness. During the flanging process, the material is subjected to a force similar to that of expanding the hole. Flanging cracking occurs when the material at the hole edge is stretched by the expanding force. Therefore, when designing flanging for parts, the maximum elongation of the material within the flanging hole is generally compared with the expansion rate to calculate the maximum flanging height, while considering a certain safety factor as the design requirement for the part's flanging height. If the required flanging height exceeds the design requirements, materials with a higher expansion rate are generally selected, often requiring a sacrifice in material strength. Alternatively, the flanging hole can be separated into a separate part and connected to the part body via welding or other methods, but this increases the number of parts and raises costs. Summary of the Invention

[0006] In view of the above-mentioned defects in the existing technology, the purpose of the present invention is to provide a mold structure that improves the forming height of sheet metal flanging, making flanging easy, low-cost, effective, and with more uniform wall thickness.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A mold structure for increasing the height of sheet metal flanging includes an upper mold body, an upper mold pressure plate, a flanging punch, and a lower mold body;

[0009] The upper die pressing plate is disposed on the lower surface of the upper die body via a pressure source component;

[0010] A pressing ring insert is provided on one side of the working surface of the upper die pressing plate, and a ring insert washer is provided between the pressing ring insert and the upper die pressing plate;

[0011] A lower mold annular insert is provided on one side of the working surface of the lower mold body, and a lower mold annular insert washer is provided between the lower mold annular insert and the lower mold body;

[0012] The hole-flipping gap t1 between the flipping punch and the lower die annular insert is set to a negative plate thickness gap;

[0013] The bottom of the punch is provided with a chamfer R1, and the top of the lower die annular insert is provided with a chamfer R2.

[0014] Preferably, the negative plate thickness gap is specifically set as follows:

[0015]

[0016] Where D1 is the diameter of the hole; h1 is the height of the hole; and t0 is the thickness of the plate.

[0017] Preferably, the chamfer R1 is specifically set as follows:

[0018]

[0019] Where λ is the porosity of the plate; a is the safety factor, with a value of 0.8 ≥ a ≥ 0.5;

[0020] The chamfer R2 is specifically set as follows:

[0021] R² ≥ 1.5R₀;

[0022] Where R0 is the maximum bending limit of the sheet material when bent at 90°.

[0023] Preferably, the annular insert washer and the lower mold annular insert washer are provided in multiple quantities.

[0024] Preferably, the hardness of the lower die annular insert and the flanging punch is ≥HRC60 and the roughness is ≤0.8.

[0025] Preferably, the pressure source component is a nitrogen cylinder.

[0026] The present invention provides a mold structure for increasing the forming height of sheet metal flanging. In the prior art flanging, the wall thickness of the flanging hole is uneven, and the sheet metal thickness becomes thinner towards the bottom of the flanging hole. With the mold structure of the present invention, the wall thickness of the flanging hole is more uniform. At the same time, compared with the prior art flanging, a greater flanging height can be obtained. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the existing mold structure;

[0028] Figure 2 yes Figure 1 An enlarged view of position A in the middle;

[0029] Figure 3 This is a schematic diagram of the mold structure of the present invention;

[0030] Figure 4 yes Figure 3 An enlarged view of position B in the middle. Detailed Implementation

[0031] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] Combination Figure 3 and Figure 4 As shown, the mold structure for increasing the forming height of sheet metal perforation provided by the present invention includes an upper mold body 10, an upper mold pressure plate 11, a perforation punch 12, and a lower mold body 13.

[0033] The upper die pressure plate 11 is located on the lower surface of the upper die body 10 via a nitrogen cylinder 14, which provides pressure force to the upper die pressure plate 11.

[0034] A pressing ring insert 15 is provided on one side of the working surface of the upper die pressing plate 11, and an annular insert washer 16 is provided between the pressing ring insert 15 and the upper die pressing plate 11.

[0035] A lower mold annular insert 17 is provided on one side of the working surface of the lower mold body 13, and a lower mold annular insert washer 18 is provided between the lower mold annular insert 17 and the lower mold body 13.

[0036] The pressure ring insert 15 and the lower die ring insert 17 maintain a uniform and higher-than-average pressure stress state between them through the flexible increase and decrease of the pressure force by the ring insert washer 16 and the lower ring insert washer 18. (The pressure force is flexibly adjusted by adding or removing a few ring insert washers.) This ensures a tight clearance fit between the pressure ring insert 15 and the lower die ring insert 17. This is because the pressure force is the force between the upper die pressure plate 11 and the lower die body 13. However, the mold structure of this invention needs to maintain a uniform pressure force that is larger than the normal pressure force around the flip hole. Therefore, by setting ring inserts and washers, and by adding more washers, the pressure force is distributed more on the upper and lower ring insert washers. This utilizes the principle of the mold balance block, which can also be called maintaining a uniform and higher-than-average pressure stress state.

[0037] The flanging gap t1 between the flanging punch 12 and the lower die annular insert 17 is set to the negative plate thickness gap, specifically as follows:

[0038]

[0039] Where D1 is the diameter of the hole; h1 is the height of the hole; and t0 is the thickness of the plate 100.

[0040] During the flanging process, in addition to the force of hole expansion, the plate 100 is also subjected to compressive stress through the negative plate thickness gap. This causes the material at the edge of the hole to be subjected to compressive stress during the flanging process, which improves the problem of cracking caused by tensile deformation of the material at the edge of the hole under the force of hole expansion in the existing technology, thereby increasing the flanging height of the plate.

[0041] The bottom of the flipping punch 12 is provided with a chamfer R1, and the top of the lower die annular insert 17 is provided with a chamfer R2. In order to achieve flipping, the bottom of the flipping punch 12 and the top of the lower die annular insert 17 need to be designed with chamfers. Otherwise, the plate 100 will be subjected to shearing force during the flipping process, which will cause cracks at the corresponding positions at the bottom of the flipping punch 12 and the top of the lower die annular insert 17, or even cut the plate 100.

[0042] The chamfer R1 is specifically set as follows:

[0043]

[0044] Where λ is the porosity of the plate material (100); a is the safety factor, with a value of 0.8 ≥ a ≥ 0.5;

[0045] The chamfer R2 is specifically set as follows:

[0046] R² ≥ 1.5R₀;

[0047] Wherein, R0 is the maximum bending limit of sheet 100 when bent at 90°.

[0048] To reduce the friction between the perforation material and the mold structure of the present invention under the negative plate thickness gap, and at the same time improve the wear resistance of the mold structure of the present invention, the lower mold annular insert 17 and the perforation punch 12 are surface treated with a hardness ≥ HRC60 and a roughness ≤ 0.8.

[0049] Example 1

[0050] A certain ultra-high strength steel material CP800 has a hole expansion rate λ of approximately 65% ​​and a plate thickness t0 of 4mm. A certain chassis control arm part has a hole diameter D1 of 70mm and a hole height h1. The part design requires a hole height of 13mm to ensure the installation sleeve requirements.

[0051] If we follow existing technology (and refer to...) Figure 1 and Figure 2 As shown), the hole gap t is 4mm, and the maximum elongation of the material inside the hole is... Based on existing technical experience formulas: The back calculation yields h1 < 13.78 mm. Considering factors such as material performance fluctuations and mold wear during the manufacturing process, a safety factor of 0.7 is taken. The design height of the hole needs to be less than 9.6 mm, otherwise there will be a significant risk of hole cracking. Therefore, it is necessary to change to a material with a higher hole expansion rate. However, for this strength and plate thickness level material, a hole expansion rate of 65% is already the highest level at present.

[0052] The mold structure adopted in this embodiment (see again) Figure 3 and Figure 4 As shown), the nitrogen cylinder 14 provides pressing force to the upper die pressing plate 11. The plate 100 is pre-punched in the previous process. After punching, the plate 100 is placed on the lower die body 13. The upper die pressing plate 11 is pressed under the pressure of the nitrogen cylinder 14. The flipping punch 12 moves down to complete the flipping.

[0053] The hole clearance t1 is set to the negative plate thickness clearance.

[0054] Because the material is subjected to both the enlarging force and the compressive force through the gap between the negative plate thickness during the hole-flipping process, the design requirements for 13mm hole-flipping parts can be met.

[0055] The mold structure in this embodiment includes an upper mold body 10, an upper mold pressure plate 11, a flipping punch 12, and a lower mold body 13.

[0056] The upper die pressure plate 11 is located on the lower surface of the upper die body 10 via a nitrogen cylinder 14, which provides pressure force to the upper die pressure plate 11.

[0057] A pressing ring insert 15 is provided on one side of the working surface of the upper die pressing plate 11, and an annular insert washer 16 is provided between the pressing ring insert 15 and the upper die pressing plate 11.

[0058] A lower mold annular insert 17 is provided on one side of the working surface of the lower mold body 13, and a lower mold annular insert washer 18 is provided between the lower mold annular insert 17 and the lower mold body 13.

[0059] Both the annular insert washer 16 and the lower annular insert washer 18 are made of flexible pressure-increasing material. The annular insert washer 16 and the lower annular insert washer 18, made of flexible pressure-increasing material, make a tight clearance fit between the pressure annular insert 15 and the lower die annular insert 17.

[0060] The specific settings for the bottom chamfer R1 of the punch 12 are as follows:

[0061]

[0062] Where a takes the value 0.7, we get 9.6mm≥R1≥1mm.

[0063] The specific chamfer R2 at the top of the lower die annular insert 17 is set as follows:

[0064] R² ≥ 1.5R₀;

[0065] Among them, the maximum bending limit R0 of the plate 100 when bent at 90° is 1mm, and R2≥1.5R0, that is, R2≥1.5mm.

[0066] To reduce the friction between the perforation material and the mold structure of this embodiment under the negative plate thickness gap, and to improve the wear resistance of the mold structure of this embodiment, the lower mold annular insert 17 and the perforation punch 12 are subjected to TD surface treatment with a hardness of HRC62 to HRC64 and a roughness ≤0.8.

[0067] Before flanging, the previous process punches a round hole with a diameter of D1-2h1, which is 70mm-2×13mm, on the board. That is, the punching diameter is 44mm. According to this embodiment, the flanging is carried out with a flanging gap t1 of 3mm, and the flanging feature with a flanging height of 13mm can be obtained.

[0068] Example 2

[0069] A certain ultra-high strength steel material QP1180 has a hole expansion rate λ of approximately 35% and a plate thickness t0 of 1.2mm. The diameter D1 of the hole in a certain seat side panel is 20mm, and the hole height is h1. The part design requires a hole height of 5mm to ensure welding requirements.

[0070] If we follow existing technology (and refer to...) Figure 1 and Figure 2 As shown), the hole gap t is 1.2 mm, and the maximum elongation of the material inside the hole is... Based on existing technical experience formulas: The back calculation yields h1 < 2.59 mm. Considering factors such as material performance fluctuations and mold wear during the manufacturing process, a safety factor of 0.7 is taken. The design height of the flip hole must be less than 1.8 mm, otherwise there will be a significant risk of cracking during the flip hole. However, a flip hole height of 5 mm is the minimum requirement for welding the seat side panel parts.

[0071] The mold structure adopted in this embodiment (see again) Figure 3 and Figure 4 As shown), the nitrogen cylinder 14 provides pressing force to the upper die pressing plate 11. The plate 100 is pre-punched in the previous process. After punching, the plate 100 is placed on the lower die body 13. The upper die pressing plate 11 is pressed under the pressure of the nitrogen cylinder 14. The flipping punch 12 moves down to complete the flipping.

[0072] The hole clearance t1 is set to the negative plate thickness clearance.

[0073] Because the material is subjected to both the enlarging force and the compressive force through the gap in the negative plate thickness during the hole-flipping process, a hole-flipping height of 5mm can be achieved.

[0074] The mold structure in this embodiment includes an upper mold body 10, an upper mold pressure plate 11, a flipping punch 12, and a lower mold body 13.

[0075] The upper die pressure plate 11 is located on the lower surface of the upper die body 10 via a nitrogen cylinder 14, which provides pressure force to the upper die pressure plate 11.

[0076] A pressing ring insert 15 is provided on one side of the working surface of the upper die pressing plate 11, and an annular insert washer 16 is provided between the pressing ring insert 15 and the upper die pressing plate 11.

[0077] A lower mold annular insert 17 is provided on one side of the working surface of the lower mold body 13, and a lower mold annular insert washer 18 is provided between the lower mold annular insert 17 and the lower mold body 13.

[0078] Both the annular insert washer 16 and the lower annular insert washer 18 are made of flexible pressure-increasing material. The annular insert washer 16 and the lower annular insert washer 18, made of flexible pressure-increasing material, make a tight clearance fit between the pressure annular insert 15 and the lower die annular insert 17.

[0079] The specific settings for the bottom chamfer R1 of the punch 12 are as follows:

[0080]

[0081] Where a takes the value 0.8, we get 2.07mm≥R1≥0.28mm.

[0082] The specific chamfer R2 at the top of the lower die annular insert 17 is set as follows:

[0083] R² ≥ 1.5R₀;

[0084] Among them, the maximum bending limit R0 of the plate 100 when bent at 90° is 1.8mm, R2≥1.5R0, that is, R2≥2.7mm.

[0085] To reduce the friction between the perforation material and the mold structure of this embodiment under the negative plate thickness gap, and to improve the wear resistance of the mold structure of this embodiment, the lower mold annular insert 17 and the perforation punch 12 are subjected to TD surface treatment with a hardness of HRC62 to HRC64 and a roughness ≤0.8.

[0086] Before flanging, the previous process punches a round hole with a diameter of D1-2h1, which is 20mm-2×5mm, on the board. That is, the punching diameter is 10mm. According to this embodiment, the flanging is carried out with a flanging gap t1 of 0.86mm, and the flanging feature with a flanging height of 5mm can be obtained.

[0087] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A mold structure for increasing the forming height of sheet metal perforation, characterized in that: Includes the upper die body, the upper die pressure plate, the flipping punch, and the lower die body; The upper die pressing plate is disposed on the lower surface of the upper die body via a pressure source component; A pressing ring insert is provided on one side of the working surface of the upper die pressing plate, and a ring insert washer is provided between the pressing ring insert and the upper die pressing plate; A lower mold annular insert is provided on one side of the working surface of the lower mold body, and a lower mold annular insert washer is provided between the lower mold annular insert and the lower mold body; The hole-flipping gap t1 between the flipping punch and the lower die annular insert is set to a negative plate thickness gap; The bottom of the piercing punch is provided with a chamfer R1, and the top of the lower die annular insert is provided with a chamfer R2. The chamfer R1 is specifically set as follows: ≥R1≥t0-t1; in, D1 is the hole expansion ratio of the board material; a is the hole diameter; 0.8 ≥ a ≥ 0.5; t0 is the thickness of the board material. The chamfer R2 is specifically set as follows: R² ≥ 1.5R₀; Where R0 is the maximum bending limit of the sheet material when bent at 90°.

2. The mold structure for increasing the forming height of sheet metal perforation according to claim 1, characterized in that, The specific setting of the negative plate thickness gap is as follows: ； Where D1 is the diameter of the hole; h1 is the height of the hole; and t0 is the thickness of the plate.

3. The mold structure for increasing the forming height of sheet metal perforation according to claim 1, characterized in that: The annular insert washer and the lower annular insert washer are provided in multiple quantities.

4. The mold structure for increasing the forming height of sheet metal perforation according to claim 1, characterized in that: The lower die annular insert and the piercing punch have a hardness ≥ HRC60 and a roughness ≤ 0.

8.

5. The mold structure for increasing the forming height of sheet metal perforation according to claim 1, characterized in that: The pressure source component is a nitrogen cylinder.

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