Stamping forming process and system of flexible transition structure of exhaust heat shield

Abstract

The application discloses a stamping forming process and system of a flexible transition structure of an exhaust heat shield, and first, a draw forming is performed to form draw protruding parts and draw rib groove parts on a flat sheet in one step, and the draw rib groove part is connected between the two draw protruding parts; the connection between the draw protruding part and the end of the draw rib groove part has a complex curved surface; the draw rib groove part has a curved surface with a preset curvature profile in the width direction of the draw rib groove part, and the material thickness of the draw rib groove part is uniformly distributed; then, the excess material of the connection complex curved surface at the two ends of the draw rib groove part is cut off through trimming, so that the draw protruding part forms a relatively rigid heat insulation unit, and the draw rib groove part forms a flexible connecting piece with a fixed length for connecting two adjacent heat insulation units. According to the application, the transition area with accurate thickness and curvature is formed through draw forming, and then the excess material is cut off through two steps of trimming, so that the formed flexible transition structure has expected shock absorption and heat compensation capacity, and has a relatively long service life.

Description

Technical Field

[0001] This invention relates to the field of stamping technology, and in particular to a stamping process and system for a flexible transition structure of an exhaust heat shield. Background Technology

[0002] Exhaust heat shields are typically designed with a flexible transition connection structure between adjacent heat shield units. This structure is usually a wavy or S-shaped thin sheet that can mitigate engine vibration-induced noise and accommodate thermal expansion through its own deformation. The thickness and contour of this flexible transition connection structure determine the heat shield's vibration damping and thermal compensation capabilities. However, traditional forming processes often cannot achieve the high-precision, high-quality forming of this flexible transition connection structure through simple procedures. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a stamping process and system for a flexible transition structure of an exhaust heat shield. First, a transition area with precise thickness and curvature is formed by drawing. Then, excess material is removed by trimming in two steps, so that the formed flexible transition structure has the expected shock absorption and thermal compensation capabilities, while also taking into account a long service life.

[0004] Technical Solution: To achieve the above objectives, the present invention provides a stamping process and system for a flexible transition structure of an exhaust heat insulation cover. First, through drawing, a drawing protrusion and a drawing bead groove are formed on a flat sheet in one step. The drawing bead groove transitionally connects two drawing protrusions. The connection between the ends of the drawing protrusion and the drawing bead groove has a complex curved surface. The drawing bead groove has a curved surface with a preset curvature profile in its width direction, and its material thickness is uniformly distributed. Then, through trimming and cutting, excess material connecting the two ends of the drawing bead groove to the complex curved surface is removed, so that the drawing protrusion constitutes a relatively rigid heat insulation unit, and the drawing bead groove constitutes a flexible connecting piece with a fixed length connecting two adjacent heat insulation units.

[0005] Furthermore, during the drawing process, the outer ring area of ​​the flat sheet is first pressed, and then the middle area of ​​the flat sheet is drawn into several drawing protrusions and several drawing rib grooves in one go.

[0006] Furthermore, the excess material at the end of the drawbead groove that connects to the complex curved surface includes a first trimming area and a second trimming area. The first trimming area is removed by vertical punching, and the second trimming area is removed by horizontal side cutting.

[0007] Furthermore, the edge contour of the end of the flexible connecting piece is first determined by the vertical punching to determine the length of the flexible connecting piece; then, the burrs located at the edge of the end of the flexible connecting piece and generated by the vertical punching are removed by the horizontal side cutting.

[0008] Furthermore, the horizontal side cutting is completed by a side cutting die. After removing the burrs, the side cutting die continues to shape the edges of the removed burrs to construct a fatigue-resistant structure.

[0009] Furthermore, the excess material at both ends of the same drawbead groove is trimmed and removed simultaneously; if multiple drawbead grooves are formed simultaneously, the excess material at the ends of two adjacent drawbead grooves is trimmed and removed simultaneously.

[0010] Furthermore, a stamping forming system includes a drawing die, a trimming die, and a side-cutting die: the drawing die is used to draw and form several drawing protrusions and drawing bead grooves in the middle region of a flat sheet in one pass; the trimming die is used to simultaneously remove excess material from the ends of multiple drawing bead grooves in a first trimming area; the side-cutting die is used to continuously remove a second trimming area, remove burrs from the edge of the flexible connecting piece, and form a fatigue-resistant structure at the edge of the flexible connecting piece through a single lateral stamping action at the end of any drawing bead groove; and the lateral stamping actions at multiple ends are performed synchronously.

[0011] Furthermore, the drawing die includes an upper drawing die body and a lower drawing die body. The bottom surface of the upper drawing die body is provided with a cavity. The lower drawing die body includes a blank holder die and a punch that fit together internally and externally. During drawing, the blank holder die and the upper drawing die body clamp the outer ring area of ​​the flat sheet and drive the flat sheet downward to contact the punch. The punch presses the middle area of ​​the flat sheet into the cavity, forming a complex surface composed of drawing protrusions and drawing rib grooves.

[0012] Furthermore, the trimming die includes a first positioning and clamping mechanism, a lower trimming die, and an upper trimming die. The first positioning and clamping mechanism uses the already formed complex surface in the middle region for positioning and clamps the middle region to fix the material sheet. After the first positioning and clamping mechanism fixes the material sheet, the upper trimming die and the lower trimming die cooperate to apply a vertical punching force to the first trimming area.

[0013] Furthermore, the side-cutting die includes a second positioning and clamping mechanism, which uses the pre-formed complex surface in the central region for positioning and clamping the central region to fix the sheet material.

[0014] The second positioning and clamping mechanism includes a lower clamping body and an upper clamping body. The lower clamping body is provided with a side-cutting die, and the side wall of the upper clamping body is provided with a horizontal guide groove.

[0015] The lower part of the horizontal guide groove is open, and the extension direction of the horizontal guide groove is consistent with the extension direction of the side-cutting cavity of the side-cutting die. When the second positioning and clamping mechanism clamps and fixes the material sheet, the horizontal guide groove and the side-cutting cavity are combined to form a side-opening side-cutting guide hole. A side-cutting punch is slidably fitted in the side-cutting guide hole, and the direction in which the side-cutting punch slides into the side-cutting guide hole is the side-cutting punching direction.

[0016] When the second positioning and clamping mechanism clamps and fixes the material sheet, the straight end section of the second trimming area and the flexible connecting piece is exposed in the side-cut guide hole, wherein the straight end section of the flexible connecting piece is attached to the upper wall of the side-cut guide hole;

[0017] The end face contour of the side-cutting punch includes a first cutting edge section and a second cutting edge section. The first cutting edge section is used for punching the second trimming area, and the second cutting edge section is used for punching the burrs on the lower edge of the flexible connecting piece.

[0018] The first cutting edge section fits against the inner wall of the side-cutting guide hole, and a gap is left between the second cutting edge section and the upper wall of the side-cutting guide hole. The cross-sectional profile of the gap is consistent with the ideal cross-sectional profile of the flexible connecting piece.

[0019] The upper surface of the side-cutting punch, the area swept by the second cutting edge segment along the side-cutting direction, includes a horizontal segment near the end and an inclined lifting segment away from the end, wherein the horizontal segment and the inclined lifting segment are smoothly connected.

[0020] Beneficial effects: The stamping process and system of the flexible transition structure of the exhaust heat insulation cover of the present invention first restricts the flow of edge material by pressing the edge, and then forms a complex surface composed of several drawing protrusions and drawing bead grooves in the middle by stamping in one go, ensuring the material thickness, uniformity and surface forming accuracy of the key area of ​​the drawing bead groove; then the length of the flexible connecting piece is determined by a vertical punching, and excess waste is removed by a lateral punching, and the defects formed at the end of the flexible connecting piece by punching are further eliminated; so that the forming accuracy and quality of the final flexible connecting piece meet the requirements of its shock absorption, thermal compensation and fatigue strength. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the forming process of the transition structure of an embodiment of the exhaust heat insulation cover of the present invention.

[0022] Figure 2 This is a schematic diagram of the structure of the lower die body of a drawing forming die according to an embodiment of the present invention.

[0023] Figure 3This is a schematic diagram illustrating the division of excess material at the end of the drawbead groove connecting to a complex curved surface, according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of a partial structure of the side cutting die cross section according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the structure of the lower mold body of the side-cutting mold according to an embodiment of the present invention. Detailed Implementation

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] As attached Figure 1-5 The aforementioned stamping process and system for a flexible transition structure of an exhaust heat shield includes a drawing die, a trimming die, and a side-cutting die.

[0028] The drawing die is used to draw a plurality of drawing protrusions 1 and drawing bead grooves 2 on a flat sheet 10 in one step. During the drawing process, the outer ring area 11 of the flat sheet 10 is first pressed, and then the middle area 12 of the flat sheet is drawn into a plurality of drawing protrusions 1 and a plurality of drawing bead grooves 2 in one step.

[0029] After forming, the drawbead groove 2 is transitionally connected between the two drawing protrusions 1; and the connection between the drawing protrusions 1 and the end of the drawbead groove 2 has a complex curved surface; the drawbead groove 2 has a curved surface with a preset curvature profile in its own width direction, and its material thickness is evenly distributed.

[0030] Preferably, the drawing die includes an upper drawing die body and a lower drawing die body. The bottom surface of the upper drawing die body is provided with a cavity. The lower drawing die body includes a pressing die 5 and a punch 6 that are interlocked. The punch 6 is fixedly installed relative to the substrate, and the pressing die 5 is installed at the top of a lifting drive mechanism.

[0031] During the drawing process, the upper surface of the blank holder 5 is first raised to be higher than the profile of the punch 6. Then, the upper drawing die body is driven to press down, and together with the blank holder 5, the outer ring area 11 of the flat sheet 10 is clamped. Subsequently, the flat sheet 10 is driven downward to contact the profile of the punch 6 in a clamped state, and is continuously pressed down until the punch 6 is pressed into the cavity. The punch 6 pushes the middle area 12 of the flat sheet 10 into the cavity, forming a complex profile composed of the drawing protrusion 1 and the drawing bead groove 2.

[0032] The upper surface of the blank holder 5 is also provided with a blank holder profile 51, which can cooperate with the drawing die body. While clamping the sheet material, it also pre-presses an undulating curved structure on the outer ring area 11, which can provide greater material flow resistance than when clamping flat. This significantly suppresses the radial flow of edge material to the central area during the subsequent middle stamping process, so that the shape change of the central area 12 is mainly compensated by its own thickness reduction. Moreover, since the edge material is locked or constrained to flow slowly, the sheet material in the central cavity is subjected to more uniform radial tensile stress. This makes the material thickness distribution of the straight part in the middle section of the rib groove more uniform. When the material flow of the central area 12 is close to the limit, it can force the sheet material to fit more tightly to the die. By reasonably selecting the initial thickness of the flat sheet 10, a drawing rib groove 2 with a clearer contour curvature and more uniform material thickness can be obtained.

[0033] Based on the formation of the drawbead groove 2 with a clear contour curvature and uniform thickness, excess material connecting the two ends of the drawbead groove 2 to the complex curved surface is removed through trimming. This makes the draw protrusion 1 form a relatively rigid heat insulation unit 3, and the drawbead groove 2 form a flexible connecting piece 4 with a fixed length connecting two adjacent heat insulation units 3. The thickness, contour length, and contour curvature of the flexible connecting piece 4 together determine its shock absorption and thermal compensation capabilities. Therefore, after the thickness and curvature are accurately formed, it is also necessary to further ensure the dimensional accuracy of its length.

[0034] like Figure 3 As shown, this solution divides the excess material at the end of the drawbead groove 2, which connects to a complex curved surface, into a first trimming area 21 and a second trimming area 22. The first trimming area 21 is removed by vertical punching, and the second trimming area 22 is removed by horizontal side cutting. By performing step-by-step punching, with the two punching feed directions being orthogonal, the total removed material is decomposed into two vertical cutting forces. This alleviates the elastic rebound and bending deformation caused by continuous unidirectional force during a single cut. Furthermore, by releasing stress slowly multiple times, the stability of the length dimension of the flexible connecting piece 4 is ensured. The first cut defines the boundary of the flexible connecting piece 4 and breaks the stress balance, causing local warping in the second trimming area 22. The second orthogonal cut separates the deformed area, avoiding severe distortion caused by a single cut. Especially in waste areas with complex curved surface structures, this results in a more uniform stress distribution. Essentially, this ensures the precision quality at the cutting edge after the excess material area is removed, and the edge contour of the flexible connecting piece 4, which is the focus of this solution, is located precisely within this cutting edge.

[0035] The excess material at both ends of the same drawbead groove 2 is trimmed and removed simultaneously; if multiple drawbead grooves 2 are formed at the same time, the excess material at the ends of two adjacent drawbead grooves 2 is trimmed and removed simultaneously.

[0036] Specifically, the edge contour of the flexible connecting piece 4 is first determined by the vertical punching of the trimming die, and the length of the flexible connecting piece 4 is accurately determined by punching both ends of a single drawbead groove 2 simultaneously; further, the trimming die is used to simultaneously remove the excess material at the ends of multiple drawbead grooves 2 in the first trimming area 21; this can further ensure the relative dimensional accuracy between multiple flexible connecting pieces 4, thereby improving the overall shock absorption and thermal compensation capabilities of the entire heat insulation cover.

[0037] Preferably, the trimming die includes a first positioning and clamping mechanism, a lower trimming die, and an upper trimming die. The first positioning and clamping mechanism uses the already formed complex surface of the central region 12 for positioning and clamps the central region 12 to fix the material sheet. After the first positioning and clamping mechanism fixes the material sheet, the upper trimming die and the lower trimming die cooperate to apply a vertical punching force to the first trimming area 21. By positioning with the already formed complex surface, the forming accuracy of the edge contour at the end of the flexible connecting piece 4 can be further improved.

[0038] After determining the length of the flexible connecting piece 4, the second trimming area 22 is further removed by horizontal side cutting to obtain the heat insulation unit 3 with the required composite profile.

[0039] In this solution, the horizontal side cutting is completed by a side cutting die, which can further remove the burrs located at the edge of the flexible connecting piece 4 and generated by vertical punching after cutting off the second trimming area 22. After removing the burrs, the edge of the removed burrs is further shaped to construct a fatigue-resistant structure, which can be a pre-set chamfer structure. Since burrs will inevitably be formed when cutting the edge contour of the flexible connecting piece 4, and burrs are essentially sharp protrusions on the edge of the part, when they exist on the edge of a flexible connector used for vibration damping and thermal stress compensation, fatigue cracks are very likely to form from the burrs on the edge of the flexible connecting piece 4 as it is repeatedly bent and deformed.

[0040] Therefore, by first vertically punching to determine the edge contour and making the burr located at the lower edge of the end face of the flexible connecting piece 4, the burr can be removed simultaneously during the second lateral punching process, thus eliminating the need for an additional deburring process, simplifying the process steps, reducing the overall production cost, and ensuring the fatigue strength of the flexible connecting piece 4.

[0041] Preferred, such as Figure 4 and 5As shown, the side-cutting die includes a second positioning and clamping mechanism. The second positioning and clamping mechanism uses the already formed complex surface of the central region 12 for positioning and clamping the central region 12 to fix the material sheet.

[0042] The second positioning and clamping mechanism includes a lower clamping body 71 and an upper clamping body 72. The lower clamping body 71 is provided with a side-cutting die 8, and the side wall of the upper clamping body 72 is provided with a horizontal guide groove.

[0043] The lower part of the horizontal guide groove is open, and the extension direction of the horizontal guide groove is consistent with the extension direction of the side-cutting cavity of the side-cutting die 8. When the second positioning and clamping mechanism clamps and fixes the material sheet, the horizontal guide groove and the side-cutting cavity are combined to form a side-opening side-cutting guide hole. The side-cutting punch 9 is slidably fitted in the side-cutting guide hole, and the direction in which the side-cutting punch 9 slides into the side-cutting guide hole is the side-cutting punching direction.

[0044] When the second positioning and clamping mechanism clamps and fixes the material sheet, the straight end sections of the second trimming area 22 and the flexible connecting piece 4 are exposed in the side-cut guide hole, wherein the straight end section of the flexible connecting piece 4 is attached to the upper wall 721 of the side-cut guide hole.

[0045] The end face contour of the side-cutting punch 9 includes a first cutting edge section 91 and a second cutting edge section 92. The first cutting edge section 91 is used for punching the second trimming area 22, and the second cutting edge section 92 is used for punching the burrs on the lower edge of the flexible connecting piece 4. The first cutting edge section 91 fits against the inner wall of the side-cutting guide hole, and a gap is left between the second cutting edge section 92 and the upper wall 721 of the side-cutting guide hole. The cross-sectional contour of the gap is consistent with the ideal cross-sectional contour of the flexible connecting piece 4.

[0046] The upper surface of the side-cutting punch 9, the area swept by the second cutting edge segment 92 along the side-cutting direction, includes a horizontal segment 81 near the end and an inclined lifting segment 82 away from the end, wherein the horizontal segment 81 and the inclined lifting segment 82 are smoothly connected.

[0047] Based on the above-mentioned side-cutting die structure, the side-cutting die can continuously remove the second trimming area 22, remove the burrs on the edge of the flexible connecting piece 4, and form the fatigue-resistant structure on the edge of the flexible connecting piece 4 through a single lateral stamping action at the end of any drawbead groove 2; and the lateral stamping actions of multiple ends are executed simultaneously.

[0048] On the one hand, it is considered that it is too idealistic to ensure that the end face contour of the flexible connecting piece 4 is completely consistent after each stamping. There will inevitably be slight deviations. In this case, it may not be possible to completely remove the burrs when deburring in the second stage of lateral punching. Therefore, a third stage is further connected to eliminate the burrs through further chamfering. On the other hand, even if the burrs can be completely removed in the second stage, the end face of the flexible connecting piece 4 and its curved surface are still sharp edges with right angle transitions. By further chamfering to form rounded corners or small slopes, stress can be effectively dispersed and fatigue strength can be significantly improved.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the above principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A stamping process for a flexible transition structure of an exhaust heat shield, characterized in that: First, by drawing, a drawing protrusion (1) and a drawing bead groove (2) are formed on a flat sheet (10) in one step. The drawing bead groove (2) is transitionally connected between the two drawing protrusions (1). The connection between the drawing protrusion (1) and the end of the drawing bead groove (2) has a complex curved surface; the drawing bead groove (2) has a curved surface with a preset curvature profile in its width direction, and its material thickness is evenly distributed. Then, by trimming and cutting, the excess material connecting the two ends of the drawing bead groove (2) to the complex curved surface is removed, so that the drawing protrusion (1) forms a relatively rigid heat insulation unit (3), and the drawing bead groove (2) forms a flexible connecting piece (4) with a fixed length that connects two adjacent heat insulation units (3).

2. The stamping process for a flexible transition structure of an exhaust heat shield according to claim 1, characterized in that: During the drawing process, the outer ring area (11) of the flat sheet (10) is first pressed, and then the middle area (12) of the flat sheet is drawn into several drawing protrusions (1) and several drawing grooves (2).

3. The stamping process for a flexible transition structure of an exhaust heat shield according to claim 2, characterized in that: The excess material at the end of the drawbead groove (2) is connected to a complex curved surface, including a first trimming area (21) and a second trimming area (22). The first trimming area (21) is removed by vertical punching, and the second trimming area (22) is removed by horizontal side cutting.

4. The stamping process for a flexible transition structure of an exhaust heat shield according to claim 3, characterized in that: First, the edge contour of the end of the flexible connecting piece (4) is determined by the vertical punching to determine the length of the flexible connecting piece (4); then, the burrs located at the edge of the end of the flexible connecting piece (4) and generated by the vertical punching are removed by the horizontal side cutting.

5. The stamping process for a flexible transition structure of an exhaust heat shield according to claim 4, characterized in that: The horizontal side cutting is completed by a side cutting die. After removing the burrs, the side cutting die continues to shape the edges of the removed burrs to construct a fatigue-resistant structure.

6. The stamping process for a flexible transition structure of an exhaust heat shield according to claim 2, characterized in that: The excess material at both ends of the same drawbead groove (2) is trimmed and removed simultaneously; if multiple drawbead grooves (2) are formed at the same time, the excess material at the ends of two adjacent drawbead grooves (2) is trimmed and removed simultaneously.

7. A stamping system according to claim 5, characterized in that, include: A drawing die is used to draw several drawing protrusions (1) and drawing bead grooves (2) in one pass in the middle region (12) of a flat sheet (10). Trimming die, used to simultaneously remove the first trimming area (21) of excess material at the ends of multiple drawbead grooves (2). The side cutting die is used to continuously remove the second trimming area (22), remove the edge burrs of the flexible connecting piece (4) and form the fatigue-resistant structure of the edge of the flexible connecting piece (4) by one side stamping action at the end of any drawbead groove (2); and the side stamping actions of multiple ends are executed simultaneously.

8. A stamping system according to claim 7, characterized in that: The drawing die includes an upper drawing die body and a lower drawing die body. The bottom surface of the upper drawing die body is provided with a cavity. The lower drawing die body includes a pressing die (5) and a punch (6) that fit together with each other. During the drawing process, the blank holder (5) clamps the outer ring area (11) of the flat sheet (10) with the upper drawing die, and drives the flat sheet (10) downward to contact the punch (6). The punch (6) presses the middle area (12) of the flat sheet (10) into the cavity to form a complex surface composed of the drawing protrusion (1) and the drawing rib groove (2).

9. A stamping system according to claim 8, characterized in that: The trimming die includes a first positioning and clamping mechanism, a lower trimming die and an upper trimming die. The first positioning and clamping mechanism uses the already formed complex surface of the middle region (12) for positioning and clamps the middle region (12) to fix the sheet. After the first positioning and clamping mechanism fixes the sheet, the upper trimming die and the lower trimming die cooperate to apply a vertical punching force to the first trimming area (21).

10. A stamping system according to claim 9, characterized in that: The side-cutting die includes a second positioning and clamping mechanism, which uses the already formed complex surface of the central region (12) for positioning and clamping the central region (12) to fix the sheet material. The second positioning and clamping mechanism includes a lower clamping body (71) and an upper clamping body (72). The lower clamping body (71) is provided with a side-cutting die (8), and the side wall of the upper clamping body (72) is provided with a horizontal guide groove. The lower part of the horizontal guide groove is open, and the extension direction of the horizontal guide groove is consistent with the extension direction of the side cutting cavity of the side cutting die (8). When the second positioning and clamping mechanism clamps and fixes the material sheet, the horizontal guide groove and the side cutting cavity are combined to form a side cutting guide hole with a side opening. A side cutting punch (9) is slidably fitted in the side cutting guide hole. The side cutting punch (9) is slidably inserted into the side cutting guide hole in the side cutting direction. When the second positioning and clamping mechanism clamps and fixes the material sheet, the straight end sections of the second trimming area (22) and the flexible connecting piece (4) are exposed in the side-cut guide hole, wherein the straight end section of the flexible connecting piece (4) is attached to the upper wall (721) of the side-cut guide hole. The end face contour of the side cutting punch (9) includes a first cutting edge section (91) and a second cutting edge section (92). The first cutting edge section (91) is used for punching the second trimming area (22), and the second cutting edge section (92) is used for punching the burrs on the lower edge of the flexible connecting piece (4). The first cutting edge segment (91) fits against the inner wall of the side-cutting guide hole, and the second cutting edge segment (92) has a gap between it and the upper wall (721) of the side-cutting guide hole. The cross-sectional profile of the gap is consistent with the ideal cross-sectional profile of the flexible connecting piece (4). The upper surface of the side-cutting punch (9) includes a horizontal section (81) near the end and an inclined lifting section (82) away from the end, the area swept by the second cutting edge section (92) along the side-cutting direction. The horizontal section (81) and the inclined lifting section (82) are smoothly connected.

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