Stamping forming method and stamping die for new energy automobile battery box tray

Abstract

The invention relates to a new energy automobile battery box tray stamping forming method and die. The method comprises the following steps: placing a rectangular aluminum alloy plate in a stamping die of a partitioned material pressing surface; arranging a draw bead in a short edge region and carrying out drawing forming, so that the material directionally flows to form a flange; the long edge area is not provided with a draw bead and is attached to the die cavity in a bulging mode, and the material flowing amount is obviously reduced. The die adopts a detachable insert type draw bead, partitioned nitrogen spring blank holder force and a cooling channel, and partitioned deformation control of high resistance of a short side and low resistance of a long side is realized. Compared with integral drawing, the weight of the material sheet is reduced by about 6 kg, the material utilization rate is increased to 87%, the forming force is reduced by 25%, the die debugging period is shortened by two thirds, the batch rejection rate is reduced to be within 1%, the method is suitable for a 1250 t common press, and the production cost of the aluminum alloy tray is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile cover production, in particular to a stamping forming method and stamping die of a new energy automobile battery box tray. BACKGROUND

[0002] The new energy automobile battery box tray is a large aluminum alloy cover for bearing and protecting the power battery, which usually requires a flange around and a shallow cavity in the middle to ensure the sealing connection and structural strength with the vehicle chassis. At present, the industry generally adopts the "whole drawing" one-step forming process: the drawing ribs are evenly arranged around the die pressure surface, and the whole domain of the sheet is forced to flow by high pressure side force to complete the forming of the cavity with small depth at one time. Although this process can realize the profile of the part, it exposes the following outstanding problems in mass production: (1) Low material utilization rate The whole drawing needs to reserve a ring-shaped pressure surface with a width of 40-50 mm and additionally increase the process supplement surface, resulting in an excessively large initial sheet size. Taking a mainstream pure electric vehicle tray as an example, the sheet weighs 38 kg, and the finished product weighs only 28.1 kg, with a material utilization rate of less than 74%, and the aluminum alloy cost accounts for a high proportion.

[0003] (2) Long development cycle and high cost In order to ensure uniform flow of the whole domain, the drawing rib height, corner radius and blank holder force need to be repeatedly adjusted, and the mold needs to be repaired in large quantities; the development cycle is usually 10-12 months, and any parameter adjustment involves the rework of the entire pressure surface, directly increasing the development cost.

[0004] (3) Narrow forming window and high scrap rate The long side of the type surface is shallow and has small curvature, which should be stretched a little to fit the mold, but in the whole drawing mode it is still forced to participate in large flow, which is prone to the contradictory defects of long side wrinkling and short side cracking; the scrap rate in batch production is often more than 6%.

[0005] (4) High requirement for equipment tonnage The whole drawing needs a forming force of 1860t and a hydraulic stretching pad pressure of 440t, which puts high requirements on the press specifications and energy consumption, limiting the universality of the production line.

[0006] (5) Fast mold wear and high maintenance cost The four-way drawing rib participates in high-pressure sliding throughout the process, resulting in severe rib groove wear, which needs to be welded and ground every 20-30 thousand times, with long maintenance downtime, which is difficult to meet the production capacity demand of new energy vehicles. SUMMARY

[0007] The present application aims to overcome the defects of the prior art, and provides a stamping forming method and stamping die for a new energy automobile battery box tray, so as to solve the problems of low material utilization rate, long mold debugging period, high cost, narrow forming window, high scrap rate, large equipment tonnage, high energy consumption, fast mold wear, and frequent maintenance.

[0008] In order to solve the above technical problems, the present application is implemented as follows: A stamping forming method for a new energy automobile battery box tray, comprising: (1) using a rectangular aluminum alloy plate, the plate has two pairs of oppositely arranged short sides and long sides; (2) placing the plate in a stamping die, the blank holder surface of the die is provided with a drawing rib in the short side area and is not provided with a drawing rib in the long side area; (3) performing drawing forming on the short side area to make the material flow and form a flange; (4) performing forming on the long side area to make the material fit the die cavity in an expansion manner, and the material flow amount of the long side is less than that of the short side; Finally, a battery box tray with a flange around and a shallow cavity in the middle is obtained.

[0009] A stamping die for implementing the method, characterized by comprising: (1) an upper die provided with a blank holder plate and optionally a drawing rib; (2) a lower die corresponding to the upper die, provided with a die cavity and a blank holder surface; (3) the blank holder surfaces of the upper die and the lower die are provided with a drawing rib in the area corresponding to the short side of the plate, and are not provided with a drawing rib in the area corresponding to the long side of the plate; (4) the blank holder plate is connected to the upper die body by a nitrogen spring, for applying a blank holding force to the plate; (5) the blank holder plate is provided with a guide element to make the blank holder plate move up and down relative to the upper die body and remain horizontal.

[0010] (6) the short side area is provided with a blank holder ring and a drawing rib at the same time, and the long side area is only provided with a blank holder ring; In this way, the material flow speed of the short side can be accurately controlled, wrinkles on the long side caused by excessive feeding can be prevented, a partition deformation mode of "short side drawing and long side expansion" is realized, and the forming stability is significantly improved.

[0011] (7) the drawing rib is a detachable insert structure, and the insert is fixed to the blank holder surface by a screw; Different heights and round angles of the rib can be quickly replaced according to the aluminum alloy grade or the thickness of the material, the mold debugging period is shortened, and the mold trial cost is reduced.

[0012] (8) The pressure plate is connected with the upper die body through nitrogen spring, and the total elastic force of the nitrogen spring in the short side area is greater than that in the long side area; By using the constant pressure characteristic of the nitrogen spring, higher blank holder force is provided in the short side to meet the drawing requirement, and lower pressure is maintained in the long side to facilitate bulging, thereby avoiding additional increase of the press tonnage.

[0013] (9) The pressure plate is provided with a guide plate or a guide column guide sleeve guide element to form a moving pair; The pressure plate is always horizontal in the stroke, and the uneven pressure gap caused by the eccentric load is prevented, thereby eliminating the risk of local wrinkling or cracking.

[0014] (10) The lower die pressure surface is provided with a groove corresponding to the upper die drawing rib in the short side area, and is a smooth surface without groove in the long side area; The short side rib-groove cooperation forms a closed flow resistance, and the long side has no flow resistance to facilitate free bulging of the plate, thereby further improving the partition deformation effect.

[0015] (10) The upper die and the lower die are both provided with cooling channels for passing in cooling liquid; The mold temperature rise during high-speed stamping can be reduced, the aluminum alloy mold sticking and rib-groove thermal wear can be reduced, the service life of the mold can be prolonged, and the batch size stability can be ensured.

[0016] The beneficial effects of the present application are: As can be seen from the above technical solution, the present application provides a stamping forming method and stamping die for a new energy automobile battery box tray. Through the partition deformation of "short side drawing + long side bulging", the long side hardly flows, the pressure surface width is reduced from 40-50mm to 15-20mm, the weight of the material sheet is reduced by about 5.9kg, and the utilization rate is increased from 74% to more than 87%. The detachable insert type drawing rib allows the rib height and rib type to be quickly replaced, and the overall pressure surface does not need to be ground during the trial stage, so the debugging cycle is shortened. The short side is provided with ribs, the long side is not provided with ribs, and the partition nitrogen spring blank holder force makes the long side free from excess material, eliminates the defects of "short side cracking and long side wrinkling", and reduces the batch scrap rate. The long side is bulged instead of drawn, the forming force and the hydraulic stretching pad pressure are reduced, and a common 1250t press in a factory can meet the requirement; the cooling channel reduces the mold temperature rise, and the long side has no drawing rib sliding, the rib-groove wear area is reduced by 50%, and the maintenance interval is increased from 20-30 thousand times to more than 80 thousand times. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be further described in detail below in combination with the drawings and embodiments: Figure 1 The figure is a schematic diagram of a new energy automobile battery box tray.

[0018] Figure 2 The figure is a schematic diagram of an upper die of a stamping die.

[0019] Figure 3 This is a schematic diagram of the upper die of a stamping die after the pressure plate has been removed.

[0020] Figure 4 This is a schematic diagram of the lower die of a stamping mold.

[0021] Figure 5 This is a schematic diagram of the material sheet required for the process of this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application. Example 1 like Figures 1-4 As shown: A stamping forming method for a battery box tray of a new energy vehicle, comprising: The material is a rectangular aluminum alloy sheet, which has two pairs of oppositely arranged short and long sides. The sheet metal is placed in a stamping die, and the blanking surface of the die has draw beads in the short side area and no draw beads in the long side area. The short side region is drawn into shape, allowing the material to flow and form a flange; The long side region is shaped so that the material fits the mold cavity in an bulging manner, and the material flow rate on the long side is less than that on the short side. The final product is a battery box tray with flanges on all four sides and a shallow cavity in the middle.

[0023] A stamping die for implementing the method, characterized in that it comprises: Upper die: Equipped with a pressure plate and optional draw beads; Lower mold: Corresponding to the upper mold, it is provided with a mold cavity and a pressing surface; The pressing surfaces of the upper and lower dies are provided with drawing ribs in the area corresponding to the short side of the plate, and are not provided with drawing ribs in the area corresponding to the long side of the plate. The pressure plate is connected to the upper mold body via a nitrogen spring and is used to apply pressure force to the sheet material; The pressure plate is equipped with a guide element to allow the pressure plate to move up and down relative to the upper mold body and remain horizontal.

[0024] Furthermore, the short side region is provided with both a blank holder and a drawbead, while the long side region is provided with only a blank holder. This allows for precise control of the material flow rate on the short side, preventing wrinkling on the long side due to excess material, and achieving a zoned deformation mode of "short side stretching and long side bulging," significantly improving forming stability.

[0025] Furthermore, the draw bead is a detachable insert structure, and the insert is fixed to the blank holder surface by screws; Ribs of different heights and rounded corners can be quickly replaced according to the aluminum alloy grade or material thickness, shortening the mold debugging cycle and reducing trial molding costs.

[0026] Furthermore, the pressure plate is connected to the upper mold body via a nitrogen spring, and the total spring force of the nitrogen spring in the short side area is greater than that in the long side area. By utilizing the constant pressure characteristic of nitrogen springs, a higher pressure side force is provided on the short side to meet the drawing requirements, while the long side maintains a lower pressure to facilitate expansion and avoids the need to increase the press tonnage.

[0027] Furthermore, the pressure plate is provided with guide plates or guide pillars and guide sleeves as guiding elements to form a moving pair; Ensure the pressure plate remains horizontal throughout the stroke to prevent uneven pressure gaps caused by eccentric loading, thereby eliminating the risk of localized wrinkling or cracking.

[0028] Furthermore, the lower die pressing surface has a groove in the short side region corresponding to the upper die drawing bead, and a smooth, groove-free surface in the long side region; The short side ribs and grooves work together to form a closed flow barrier, while the long side is unobstructed, which allows the sheet material to expand freely and further improves the zoned deformation effect.

[0029] Furthermore, both the upper and lower molds are provided with cooling channels for introducing coolant; It can reduce the temperature rise of the die during high-speed stamping, reduce aluminum alloy sticking to the die and thermal wear of the rib groove, extend the die life and ensure batch dimensional stability.

[0030] Example 2 A battery box tray forming process that can be implemented on a 1250t single-action press can be reproduced without additional data: (1) Material feeding: according to Figure 5 The outline is made of 3.2mm thick 6-series aluminum alloy rectangular plate, with the surface pre-coated with dry drawing oil.

[0031] Mold preparation: (2) Upper mold ( Figure 2 The short side area has been fitted with 6 mm high removable insert-type draw beads; the long side area remains smooth. Lower die ( Figure 4 A 6.2mm deep groove is machined at the corresponding position on the short side, while there is no groove on the long side. Nitrogen springs are evenly distributed around the pressure plate, with 3 springs on each short side and 2 springs on each long side. After installation, the total spring force on the short side is 30% higher than that on the long side.

[0032] (3) Molding: The mold is hung into the 1250t press, the upper die cooling channel is connected to the 20℃ circulating water, and the lower die is also connected to the water return pipeline.

[0033] (4) Forming: After the plate is positioned, the slider is lowered by 150mm: Short side: the draw bead is first pressed into the groove to form a closed resistance flow, the material flows along the short side in a directional manner, and a 25mm wide flange is generated; Long side: no resistance flow, the plate is directly bulged in the mold cavity, the side wall is attached to the mold, and almost no material slides in the long side direction.

[0034] After reaching the lower dead point, the slider returns, the nitrogen spring ejects the pressing plate, and the material supporting pin supports the part.

[0035] (5) Part taking and inspection The tray is manually taken out, the long side is visually inspected for no wrinkles, the short side is visually inspected for no cracks, the flange around is visually inspected for flatness, and the subsequent edge cutting and turning process can be directly entered.

[0036] By using the above steps, the new energy automobile battery box tray with flanges around and a shallow cavity in the middle can be stably produced on the 1250t press in a common factory building.

[0037] The above is only an embodiment provided by the present application and does not limit the present application, although the present application is described in detail with reference to the embodiment, for those skilled in the art, the technical solutions recorded in the foregoing embodiment can be modified, or some technical features can be replaced by equivalents, but any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A stamping forming method for a battery box tray of a new energy vehicle, characterized in that, include: The material is a rectangular aluminum alloy sheet, which has two pairs of oppositely arranged short and long sides. The sheet metal is placed in a stamping die, and the blanking surface of the die has draw beads in the short side area and no draw beads in the long side area. The short side region is drawn into shape, allowing the material to flow and form a flange; The long side region is shaped so that the material fits the mold cavity in an bulging manner, and the material flow rate on the long side is less than that on the short side. The final product is a battery box tray with flanges on all four sides and a shallow cavity in the middle.

2. A stamping die for implementing the method of claim 1, characterized in that, include: Upper die: Equipped with a pressure plate and optional draw beads; Lower mold: Corresponding to the upper mold, it is provided with a mold cavity and a pressing surface; The areas of the upper and lower die pressing surfaces corresponding to the short side of the sheet metal are provided with drawing ribs, while the areas corresponding to the long side of the sheet metal are not provided with drawing ribs. The pressure plate is connected to the upper mold body via a nitrogen spring and is used to apply pressure force to the sheet material; The pressure plate is equipped with a guide element to allow the pressure plate to move up and down relative to the upper mold body and remain horizontal.

3. The stamping die according to claim 2, characterized in that: The draw beads are detachable insert structures, and the inserts are fixed to the pressure surface with screws so that draw beads of different heights can be replaced according to the thickness of the sheet or the material grade.

4. The stamping die according to claim 2, characterized in that: The pressure plate guiding element is a guide plate, guide post, or guide sleeve. The guide plate or guide post is fixed to the upper mold body, and the guide sleeve is fixed to the pressure plate, forming a sliding pair.

5. The stamping die according to claim 2, characterized in that: The nitrogen springs are evenly distributed around the perimeter of the pressure plate, and the total elastic force of the nitrogen springs in the short side region is greater than that in the long side region, so as to match the greater pressure force required for short side drawing.

6. The stamping die according to claim 2, characterized in that: The blanking surface of the lower die has a groove in the short side region that corresponds to the drawing bead of the upper die, and is a smooth surface without grooves in the long side region.

7. The stamping die according to claim 2, characterized in that: Both the upper and lower molds are equipped with cooling channels for introducing coolant to reduce the temperature rise of the molds during the forming process.

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