Opening drawing method for automobile rear floor

Abstract

The invention relates to an opening drawing method for an automobile rear floor, which comprises the following steps of: setting a pressing surface on a plate forming an opening side of the rear floor as a first pressing surface, setting a pressing surface forming other side surfaces of the rear floor as a second pressing surface, and arranging a fracture at the joint of the first pressing surface and the second pressing surface; the height of the first material pressing surface is higher than that of the second material pressing surface; a transition part is arranged between the first material pressing surface and the fracture and is used for realizing the transition of the material at the first material pressing surface to the fracture; a first step surface is arranged on the inner side of the first material pressing surface; and the fracture is provided with a modeling part used for increasing the amount of materials flowing into the fracture. According to the scheme, the first material pressing face and the second material pressing face are separated through the fracture, and meanwhile, the height difference exists between the first material pressing face and the second material pressing face, so that the overall inflow amount of materials can be reduced during plate drawing, drawing wrinkling and cracking in the drawing process are avoided, and the drawing quality is improved. And the production of the automobile rear floor workpieces is more stable.

Description

A method for drawing an opening in the rear floor of a car Technical Field

[0001] This invention relates to the technical field of automotive rear floor processing, and more specifically, to an opening drawing method for automotive rear floor. Background Technology

[0002] The rear floor of a car is a deep-drawn part with a significant drawing depth, typically used to store a spare tire or the battery box of a new energy vehicle. The current stamping process for the rear floor consists of drawing, trimming, and punching. The drawing process first shapes the sheet metal; the trimming process removes excess material; and the punching process punches out the required holes in the drawn sheet metal. Once the punching is completed, the processing steps for one rear floor stamping part are finished.

[0003] The conventional design for the drawing process involves setting the blank holder surface within a reference plane, with the blank held in place by the first draw beads and the blank holder surface. Depending on the dimensional differences of the back blank workpiece, the material flow rate is adjusted during the blank holding process based on the depth and size of the first draw beads and the required clamping force. This controls the material flow rate at different parts of the blank to meet the material flow requirements of different parts of the drawn workpiece. However, because the back blank is a deep-drawn part with almost vertical sidewalls, a large drawing depth, and a maximum material flow distance exceeding 120 mm, the large material flow rate can easily lead to wrinkling and cracking during the drawing process, resulting in unstable production. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem that excessive material flow during the drawing process of rear floor workpieces in the prior art easily leads to wrinkling and cracking during the drawing process. This invention provides an open drawing method for automotive rear floor. The drawing method in this solution can reduce the maximum material flow distance and avoid wrinkling and cracking of the sheet material during the drawing process.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for drawing an opening in the rear floor of an automobile, comprising the following steps: Step 1: setting the pressing surface on the sheet metal forming the opening side of the rear floor as the first pressing surface, and the pressing surfaces forming the other sides of the rear floor as the second pressing surface, wherein a break is provided at the connection between the first pressing surface and the second pressing surface; Step 2: making the height of the first pressing surface higher than the height of the second pressing surface; Step 3: providing a transition portion between the first pressing surface and the break to facilitate the transition of material from the first pressing surface to the break; Step 4: providing a first stepped surface on the inner side of the first pressing surface; Step 5: providing a shaping portion at the break to increase the amount of material flowing into the break.

[0006] In this design, the fracture surface separates the first and second pressing surfaces, making them discontinuous. There are two fracture surfaces, located on either side of the opening of the molded floor workpiece. The height of the first pressing surface is greater than that of the second pressing surface, meaning the distance between the first pressing surface and the bottom surface of the floor workpiece is smaller than the distance between the second pressing surface and the bottom surface of the floor workpiece.

[0007] This solution proposes an open-ended drawing method for automotive rear floor panels. A break is created between the first and second blanking surfaces, allowing the compressive stress generated during material flow from the first and second blanking surfaces to be released at the break. Compared to existing technologies with a continuous circular blanking surface, this method largely avoids material compression when the material flow is excessive, preventing wrinkling and thickening during drawing, and significantly reducing the risk of cracking. Furthermore, the height difference between the first and second blanking surfaces, with the first blanking surface higher, results in a longer sheet metal line length locked within the first draw bead during stamping. This means more material is available at the start of drawing, reducing the amount of material needed for forming and further lowering the risk of wrinkling and cracking. The break also facilitates material transition between the first and second blanking surfaces. Additionally, the transition section, the first step surface, and the shaping section further enhance material flow during drawing.

[0008] The open-ended drawing method for the rear floor of an automobile of the present invention separates the first pressing surface and the second pressing surface by setting the break, and at the same time makes a height difference between the first pressing surface and the second pressing surface, so as to reduce the overall material flow during sheet drawing, avoid wrinkling and cracking during drawing, and make the production of the rear floor of the automobile more stable.

[0009] Preferably, in step two, the height difference between the first and second pressing surfaces is 80mm-100mm. Stress test analysis of automotive rear floor workpieces shows that setting the height difference between the first and second pressing surfaces between 80mm-100mm ensures that the material flow during the drawing process meets the production requirements of preventing wrinkles and cracking. The specific height difference between the first and second pressing surfaces can be selected according to the dimensions of different automotive rear floor workpiece models.

[0010] Preferably, in step three, the transition portion includes a first parting line and a first draw bead located on the first blank holder surface. Both the first parting line and the first draw bead extend towards the fracture surface on the first blank holder surface. The first parting line and the first draw bead gradually turn outward on the first blank holder surface until they reach the fracture surface to facilitate the material transition of the sheet metal during drawing, making the process of material flowing into the fracture surface smoother.

[0011] Preferably, in step four, the first stepped surface is located inside the first pressing surface. The first stepped surface being located inside the first pressing surface means that a partial stepped surface is added to the inside of the first pressing surface. The first stepped surface extends to the fracture surface. The step surface increases the resistance to material flow, adjusts the material flow rate, and prevents wrinkling during stretching.

[0012] Preferably, the shaping portion includes a recess, a second stepped surface, and reinforcing ribs. The recess and reinforcing ribs are both located at the fracture point, and the second stepped surface is located on the second blank holder surface. The recess, second stepped surface, and reinforcing ribs at the fracture point can all increase the material flow rate during drawing, further preventing wrinkling and cracking during the drawing process.

[0013] Preferably, the concave shape is located at the bottom of the fracture surface and is trapezoidal. The top edge of the trapezoidal concave shape is closer to the bottom edge of the fracture surface than the bottom edge of the trapezoidal concave shape. The two sides of the trapezoidal concave shape face the first pressure surface and the second pressure surface, respectively. Since the fracture surface is located on both sides of the first pressure surface, and the fracture surface is located at the corner of the formed automotive rear floor workpiece, setting the concave shape as a whole can make the material flow at the corner of the workpiece more stable during drawing.

[0014] The reinforcing rib is closer to the bottom surface of the rear floor workpiece than the recess, and the axis of the reinforcing rib is parallel to the trapezoidal base of the recess. The reinforcing rib can accommodate excessive material flow and prevent material accumulation and wrinkling.

[0015] The second stepped surface is located inside the second pressing surface. Specifically, it is a supplementary stepped surface added to the inner side of the second pressing surface, extending to the fracture surface. The second stepped surface increases the material inflow resistance on the second pressing surface, adjusts the material inflow rate, and prevents wrinkling during drawing.

[0016] Preferably, the second blank holder surface is provided with a second parting line and a second draw bead, both of which are located on the second blank holder surface and extend to the fracture. The second parting line and the second draw bead gradually turn outward on the second blank holder surface until they extend into the fracture to facilitate the material transition of the sheet metal during drawing, making the process of material flowing into the fracture smoother.

[0017] Preferably, the sheet metal has a first arc-shaped edge and a second arc-shaped edge, which are symmetrical about the axis of the long side of the sheet metal. Currently, most automotive rear floor sheets are trapezoidal. This solution, by setting the first and second arc-shaped edges on a square sheet metal, achieves a smaller overall length and width of the sheet metal while meeting the workpiece drawing requirements, resulting in higher overall material utilization.

[0018] Compared with the prior art, the beneficial effects of the present invention are: the open drawing method of the automobile rear floor of the present invention separates the first pressing surface and the second pressing surface by setting the break, and at the same time makes there a height difference between the first pressing surface and the second pressing surface, so as to reduce the material flow during sheet drawing, avoid wrinkling and cracking during drawing, and make the production of automobile rear floor workpieces more stable. Attached Figure Description

[0019] Figure 1 is a flowchart of a method for drawing an opening in the rear floor of an automobile; Figure 2 is a model diagram of the formed workpiece of the rear floor of an automobile; Figure 3 is a schematic diagram of the structure of the rear floor workpiece formed by the opening drawing method of the rear floor of this solution; Figure 4 is a partial view of the actual workpiece of the rear floor of the automobile in this solution; Figure 5 is a comparison diagram of the cross-sectional orientation of the rear floor workpiece of this solution and the prior art; Figure 6 is a schematic diagram of the height difference between the first and second pressing surfaces of the rear floor workpiece formed by the opening drawing method of the rear floor of this solution; Figure 7 is a schematic diagram of the sheet shape of the rear floor workpiece of the rear floor in this solution; Figure 8 is a schematic diagram of the sheet shape of the rear floor workpiece of the prior art.

[0020] Among them, 1. First blank holder surface; 2. Second blank holder surface; 3. Fracture; 4. First step surface; 5. First parting line; 6. First draw bead; 7. Recess; 8. Second step surface; 9. Adding rib; 10. Second parting line; 11. Second draw bead; 13. First arc edge; 14. Second arc edge. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only, representing schematic diagrams rather than actual physical objects, and should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0022] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0023] This embodiment is a first embodiment of a drawing method for an opening in the rear floor of an automobile, as shown in Figure 1, including the following steps: Step 1: The pressing surface on the sheet metal forming the opening side of the rear floor is designated as the first pressing surface 1, and the pressing surface forming the opening side of the rear floor workpiece is shown in Figure 2. The pressing surfaces formed on the other sides of the rear floor are designated as the second pressing surface 2, and a break 3 is provided at the connection between the first pressing surface 1 and the second pressing surface 2; Step 2: The height of the first pressing surface 1 is made higher than the height of the second pressing surface 2; Step 3: A transition section is provided between the first pressing surface 1 and the break 3 to facilitate the transition of material from the first pressing surface 1 to the break 3; Step 4: A first step surface 4 is provided on the inner side of the first pressing surface 1; Step 5: A shaping section is provided at the break 3 to increase the amount of material flowing into the break 3.

[0024] Specifically, in this design, the break 3 separates the first pressing surface 1 and the second pressing surface 2, making them discontinuous. There are two breaks 3, located on either side of the opening of the molded floor workpiece. The height of the first pressing surface 1 is greater than the height of the second pressing surface 2, meaning the distance between the first pressing surface 1 and the bottom surface of the floor workpiece is smaller than the distance between the second pressing surface 2 and the bottom surface of the floor workpiece.

[0025] The working principle or process of this embodiment is as follows: As shown in Figures 3 and 4, a break 3 is set between the first pressing surface 1 and the second pressing surface 2, so that the compressive stress generated when the material of the back floor workpiece flows into the first pressing surface 1 and the second pressing surface 2 during the drawing process will be released at the break 3. Therefore, compared with the existing technology of the whole-circle pressing surface, it can basically avoid material extrusion when the amount of drawing material is too large, which can avoid wrinkling and material thickening during drawing, and also greatly reduce the risk of cracking.

[0026] As shown in Figure 5, there is a height difference between the first pressing surface 1 and the second pressing surface 2, and the first pressing surface 1 is higher than the second pressing surface 2. Due to the difference in height between the two pressing surfaces, the length of the sheet material locked in the first drawing bead 6 is longer during stamping. This means that there is more material in the first drawing bead 6 when drawing begins, and less material needs to flow in from the outside to supplement the material required for forming. This can further reduce the risk of wrinkling and cracking during drawing.

[0027] Furthermore, the break point 3 facilitates the transition of material between the first pressing surface 1 and the second pressing surface 2. Additionally, the transition section, the first step surface 4, and the shaping section also allow for smoother material flow during sheet metal drawing.

[0028] The beneficial effects of this embodiment are as follows: The open drawing method for the rear floor of the automobile of the present invention separates the first pressing surface 1 and the second pressing surface 2 by setting the break 3, and at the same time makes a height difference between the first pressing surface 1 and the second pressing surface 2, so that the overall inflow of material can be reduced when the sheet is drawn, avoiding the occurrence of drawing wrinkles and cracks during the drawing process, and making the production of the rear floor of the automobile more stable.

[0029] Example 2 This example is a second embodiment of a method for drawing an opening in the rear floor of an automobile. Based on Example 1, this example further defines steps 1-5.

[0030] Specifically, as shown in Figures 5 and 6, in step two, the height difference D between the first pressing surface 1 and the second pressing surface 2 is 80mm-100mm.

[0031] As shown in Figure 4, in step three, the transition portion includes a first parting line 5 and a first draw bead 6 located on the first pressing surface 1. Both the first parting line 5 and the first draw bead 6 extend toward the fracture 3 on the first pressing surface 1.

[0032] In step four, the first step surface 4 is located inside the first pressing surface 1 and extends to the fracture surface 3.

[0033] The shaping part includes a concave 7, a second step surface 8, and a reinforcing rib 9. Both the concave 7 and the reinforcing rib 9 are located at the break point 3, and the second step surface 8 is located on the second pressing surface 2.

[0034] The concave 7 is located at the bottom of the fracture 3 and is trapezoidal. The top edge of the trapezoidal concave 7 is closer to the bottom edge of the fracture 3 than the bottom edge of the trapezoidal concave 7. The two sides of the trapezoidal concave 7 are respectively facing the first pressing surface 1 and the second pressing surface 2.

[0035] The reinforcing rib 9 is closer to the bottom surface of the rear floor workpiece than the recess 7, and the axis of the reinforcing rib 9 is parallel to the trapezoidal bottom edge of the recess 7.

[0036] The second step surface 8 is located inside the second pressing surface 2.

[0037] The second blanking surface 2 is provided with a second parting line 10 and a second draw bead 11. The second parting line 10 and the second draw bead 11 are both located on the second blanking surface 2 and extend to the break 3.

[0038] The beneficial effects of this embodiment are as follows: When the height difference between the first blank holder surface 1 and the second blank holder surface 2 is set between 80mm and 100mm, the material inflow during the drawing process can meet the production requirements of preventing wrinkles and cracks. The first parting line 5 and the first draw bead 6 gradually turn outward on the first blank holder surface 1 until they extend into the fracture 3 to facilitate the material transition of the sheet metal during drawing, making the material flow into the fracture 3 smoother. The first stepped surface 4 is located inside the first blank holder surface 1, that is, a process supplement of the stepped surface inside the first blank holder surface 1. The first stepped surface 4 extends to the fracture 3. The setting of the stepped surface can increase the resistance to material inflow, adjust the material inflow, and avoid wrinkling during drawing.

[0039] The recess 7, the second step surface 8, and the reinforcing rib 9 at the fracture 3 all contribute to increasing the material flow during drawing, further preventing wrinkling and cracking. Since the fracture 3 is located on both sides of the first blank holder surface 1, and at a corner on the formed automotive rear floor workpiece, designing the recess 7 as a trapezoidal shape stabilizes the material flow at the corners during drawing. The reinforcing rib accommodates excessive material flow, preventing material accumulation and wrinkling. The second step surface 8 increases the material flow resistance on the second blank holder surface 2, regulating the material flow and preventing wrinkling during drawing.

[0040] The second parting line 10 and the second draw bead 11 gradually turn outward on the second blanking surface 2 until they extend into the fracture 3 to facilitate the material transition of the sheet metal during drawing, making the process of material flowing into the fracture 3 smoother.

[0041] Example 3 This example is the third embodiment of an opening drawing method for the rear floor of an automobile. Based on Examples 1 and 2, this example further defines the shape of the sheet material.

[0042] As shown in Figure 7, the sheet metal is provided with a first arc-shaped edge 13 and a second arc-shaped edge 14, which are symmetrical about the axis of the long side of the sheet metal.

[0043] The beneficial effects of this embodiment are as follows: After setting the arc edge on the sheet metal, the sheet metal can be used to complete the drawing and forming of the automotive rear floor workpiece with a smaller size, as shown in Figure 7. In Figure 7, the red framed part is the material shape required for producing the sheet metal, and the green framed part is the sheet metal shape. The sheet metal blank in this solution has a weight of 9.16 kg, and its material utilization rate after drawing and forming reaches 73%. In contrast, the weight of a conventional sheet metal blank is 9.47 kg, as shown in Figure 8. In Figure 8, the red framed part is the material shape required for producing the sheet metal, and the green framed part is the sheet metal shape, with a material utilization rate of only 70.7%. Furthermore, the length and width of the sheet metal in this solution are smaller than those of conventional sheet metal, resulting in less waste generated during the processing and production of the sheet metal.

[0044] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0045] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for drawing an opening in the rear floor of a car, characterized in that, The process includes the following steps: Step 1: The pressing surface on the side of the floor opening formed on the board is designated as the first pressing surface (1), and the pressing surfaces on the other sides of the floor are designated as the second pressing surface (2). A break (3) is provided at the connection between the first pressing surface (1) and the second pressing surface (2); Step 2: The height of the first pressing surface (1) is made to be higher than the height of the second pressing surface (2); Step 3: A transition section is provided between the first pressing surface (1) and the fracture (3) to facilitate the transition of material from the first pressing surface (1) to the fracture (3); Step 4: A first step surface (4) is provided on the first pressing surface (1); Step 5: A shaping section is provided at the fracture (3) to increase the amount of material flowing into the fracture.

2. The method for opening and drawing a rear floor of an automobile according to claim 1, characterized in that, In step two, the height difference between the first pressing surface (1) and the second pressing surface (2) is 80mm-100mm.

3. The method for drawing an opening in the rear floor of an automobile according to claim 1, characterized in that, In step three, the transition portion includes a first parting line (5) and a first draw bead (6) located on the first blank holder surface (1), and both the first parting line (5) and the first draw bead (6) extend toward the break (3) on the first blank holder surface (1).

4. The method for opening and drawing a rear floor of an automobile according to claim 3, characterized in that, In step four, the first step surface (4) is located inside the first pressing surface (1).

5. The method for drawing an opening in the rear floor of a car according to claim 1, characterized in that, In step five, the shaping part includes a concave rim (7), a second step surface (8), and reinforcing ribs (9). The concave rim (7) and the reinforcing ribs (9) are both located at the break (3), and the second step surface (8) is located on the second pressing surface (2).

6. The method for drawing an opening in the rear floor of an automobile according to claim 5, characterized in that, The concave (7) is located at the bottom of the fracture (3) and the concave (7) is trapezoidal. The top edge of the trapezoidal concave (7) is closer to the bottom edge of the fracture (3) than the bottom edge of the trapezoidal concave (7). The two sides of the trapezoidal concave (7) are respectively facing the first pressing surface (1) and the second pressing surface (2).

7. The method for drawing an opening in the rear floor of a car according to claim 6, characterized in that, The reinforcing rib (9) is closer to the bottom surface of the rear floor workpiece than the recess (7), and the axis of the reinforcing rib (9) is parallel to the trapezoidal bottom edge of the recess (7).

8. The method for drawing an opening in the rear floor of an automobile according to claim 5, characterized in that, The second step surface (8) is located inside the second pressing surface (2).

9. The method for drawing an opening in the rear floor of an automobile according to claim 1, characterized in that, The second blanking surface (2) is provided with a second parting line (10) and a second draw bead (11). The second parting line (10) and the second draw bead (11) are both located on the second blanking surface (2) and extend to the fracture (3).

10. The method for drawing an opening in the rear floor of an automobile according to claim 1, characterized in that, The sheet metal is provided with a first arc-shaped edge (13) and a second arc-shaped edge (14), and the first arc-shaped edge (13) and the second arc-shaped edge (14) are symmetrical along the axis of the long side of the sheet metal.

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