A method of forming a conical part and a conical part

Abstract

The application relates to a forming method of a conical part and the conical part, and the forming method of the conical part comprises the following steps: preparing a conical pipe blank, the conical pipe blank has a surplus section and a forming section connected with each other, the surplus section extends along the inclined direction of the profile of the forming section, and the surplus section is open upward; the forming section of the conical pipe blank is arranged in a cavity of a female die, a pressure ring is arranged on the surplus section of the conical pipe blank, and a pressure force is applied to the pressure ring; a male die is lowered to perform rigid bulging with the female die, and during the rigid bulging, the pressure force is configured to inhibit the surplus section from wrinkling and allow the material of the surplus section to flow to the forming section to supplement material until the male die is closed. The forming method belongs to integral forming, has few welds, low manufacturing cost, no need of sealing, the material of the surplus section flows to the forming section to supplement material, the bottom is avoided from being stacked with material, the thinning rate is controlled within 15%, the surplus section is inhibited from wrinkking and cracking, the forming rejection rate is reduced, and the forming stability is improved.

Description

Technical Field

[0001] This invention relates to the field of cone-shaped part manufacturing technology, and in particular to a method for forming a cone-shaped part and a cone-shaped part. Background Technology

[0002] The cone-shaped component 1 of an aero-engine is generally a thin-walled sheet metal part made of high-temperature alloy, such as... Figures 1-3 As shown, the overall height H of the conical part 1 is 400mm-500mm. The conical part 1 has an upper opening 11 and a lower opening 12. The diameter D of the upper opening 11 is... 11 The diameter D of the lower opening 12 is 450mm-550mm. 12 The diameter D of the upper opening 11 is 40-55mm. 11 The diameter D of the lower opening 12 12 ≈10:1, belonging to the category of large conical parts with "large height and large diameter difference". The main characteristics of this type of part are that the overall height is relatively high and the size of the lower opening is relatively small. The cross-sectional line 13 of the conical part 1 is a smooth outward convex arc. The shape of the conical part 1 is sharp, the curvature changes greatly and has a specific pattern. It is easy to crack during molding, the thinning rate is difficult to control, and the overall molding is difficult.

[0003] In the prior art, there are two molding schemes for the cone part 1: segmented molding and integral molding.

[0004] During segmented forming, the conical part 1 is evenly divided into three segments along its axial direction. Each segment is formed by winding and welding fan-shaped blanks into conical tube segment blanks. Each segment is then formed by flexible expansion processes such as air expansion or liquid expansion. They are then welded together to form the whole conical part 1. The whole part is then shaped. The formed conical part 1 has an axial weld formed by winding and welding three fan-shaped blanks and two circumferential welds formed by welding two adjacent segments. This forming process reduces the deformation and thinning rate of individual segments by "equally dividing and segmenting". The curvature change of each segment is reduced, the deformation of the billet is significantly reduced, the material flows smoothly during expansion, and there is basically no stacking of material, which avoids cracking. The process is simple and easy to implement. However, the formed cone part 1 has many welds, which are the biggest risk points for cracking and seriously affect the overall strength and reliability of the high-temperature alloy parts (welds are prone to failure under high temperature and high pressure conditions). Moreover, the process is complicated and the production efficiency is low. It requires three sets of forming molds, two sets of welding fixtures, three sets of cutting fixtures and one set of shaping molds. The number of molds and fixtures is large, and the size of the molds and fixtures is also large due to the large size of the parts, resulting in high manufacturing costs and high subsequent maintenance costs.

[0005] During the overall forming process, a conical tube blank is formed by winding and welding a fan-shaped blank. Then, the conical tube blank is flexibly expanded as a whole. During the flexible expansion, both the upper and lower ends of the conical tube blank need to be sealed. There is no distance between the conical tube blank and the bottom of the cavity of the forming mold. The formed conical part 1 ultimately has only one axial weld formed by the winding and welding of the fan-shaped blank, which effectively reduces the risk of weld cracking in the formed conical part 1 and is low in cost. However, the rigidity of pipe parts is affected by the pipe diameter. Under the premise of the same wall thickness, the larger the pipe diameter, the smaller the rigidity and the easier it is to deform. Based on the shape characteristics of the upper opening 11 of the conical part 1 having a large diameter and the lower opening 12 having a small diameter, the upper end of the conical part 1 has low rigidity and the lower end has high rigidity. The upper end deforms first, that is, it deforms from top to bottom during the forming process. The material inside the blank flows downward. Because the lower opening 12 of the conical part 1 is too small, there is not enough space at the bottom of the part for the accumulated material to expand and flatten. Finally, the material is piled up at the lower opening 12. The scrap rate of the conical part is very high and the forming stability is not high.

[0006] Meanwhile, both split molding and integral molding utilize flexible bulging technology. During flexible bulging, both the upper and lower ends of the tapered tube blank need to be sealed. The bottom sealing position is the profile extending from the bottom of the tapered tube blank 2. However, the diameter of the lower opening of the tapered tube blank 2 is small. Extending along the curvature of the lower opening to form the sealing profile will make the bottom opening even smaller. That is, the effective area of ​​the bottom sealing section is small during flexible bulging, and the area that can be used for sealing is very small. Often, due to insufficient sealing strength, the seal fails during the molding process, causing water leakage and pressure loss, resulting in molding interruption and greatly affecting production efficiency.

[0007] Therefore, there is an urgent need for a forming method for cone-shaped parts and a cone-shaped part in order to solve the above-mentioned technical problems. Summary of the Invention

[0008] One object of the present invention is to provide a method for forming a cone-shaped part, so as to at least solve one of the above-mentioned problems.

[0009] To achieve the above objectives, the present invention provides a method for forming a conical part, the conical part having an upper opening and a lower opening, wherein the diameter D of the upper opening is... 11 and the diameter D of the lower opening 12 The ratio is 10:1, the height H of the conical part is 400mm-500mm, and the diameter D of the lower opening is... 12 The diameter is 40-55mm, and the cross-sectional line of the conical part is a smooth, outwardly convex arc, including the following steps: A tapered tube blank is prepared, the tapered tube blank having a connected allowance section and a forming section, the allowance section extending along the inclined direction of the profile of the forming section, and the allowance section being connected to the large diameter end of the forming section; The forming section of the tapered tube blank is placed in the cavity of the die, and the blank holder is pressed onto the remaining section of the tapered tube blank, and a blank holder force is applied to the blank holder. The punch descends and closes with the die to perform rigid bulging. During the rigid bulging process, the blank holder force is configured to both suppress wrinkling of the allowance section and allow the material of the allowance section to flow and replenish the forming section until the punch closes.

[0010] Furthermore, the length L1 of the allowance segment is 120mm-130mm.

[0011] Furthermore, the taper α of the tapered tube blank is 60°-70°, the diameter of the bottom opening of the tapered tube blank is 5mm-10mm smaller than the diameter of the bottom opening of the cavity, and the axial distance d from the bottom opening of the tapered tube blank to the bottom opening of the cavity is 90mm-100mm.

[0012] Furthermore, the blank holder force is 100t-200t.

[0013] Furthermore, the coefficient of friction between the pressure ring and the tapered tube blank and the coefficient of friction between the die and the tapered tube blank are both 0.08-0.1.

[0014] Furthermore, the contact surfaces of the pressure ring and the tapered tube blank, as well as the contact surfaces of the die and the tapered tube blank, are coated with graphite castor oil.

[0015] Furthermore, the downward speed of the punch is 2mm / s-3mm / s, and the downward speed of the punch is coupled with the blank holder force and the coefficient of friction to control the material flow rate of the allowance section.

[0016] Furthermore, the inner diameter of the pressure ring is 0.2 mm larger than the outer diameter of the punch.

[0017] Furthermore, after preparing the tapered tube blank and before placing the forming section of the tapered tube blank into the cavity of the die, the method further includes the step of performing vacuum solution treatment on the tapered tube blank.

[0018] Another object of the present invention is to provide a conical part to at least solve one of the above-mentioned problems.

[0019] To achieve the above objectives, the present invention provides a conical part, which is formed by the forming method of the conical part according to any of the above-mentioned schemes, wherein the final contour error of the conical part is not greater than 1.5 mm and the thinning rate is not greater than 15%.

[0020] The beneficial effects of this invention are as follows: The present invention provides a method for forming a conical part, which has an upper opening and a lower opening, wherein the diameter D of the upper opening is... 11 and the diameter D of the lower opening 12The ratio is 10:1, the height H of the conical part is 400mm-500mm, and the diameter D of the lower opening is... 12 For a diameter of 40-55mm, the cross-section of the conical part is a smooth, outwardly convex arc, including the following steps: Prepare a tapered tube blank, which has a connected allowance section and a forming section. The allowance section extends along the inclined direction of the forming section's profile and opens upwards. The forming section of the tapered tube blank is placed in the cavity of the die, and the blank holder is pressed onto the remaining section of the tapered tube blank, and a blank holder force is applied to the blank holder. The punch descends and closes with the die to perform rigid bulging. During the rigid bulging process, the blank holder force is configured to both suppress wrinkling in the allowance section and allow the material in the allowance section to flow to the forming section to replenish the material until the punch closes.

[0021] The forming method for the cone-shaped part provided by this invention is an integral forming method with fewer processes and fewer welds, which improves the overall strength and reliability of the cone-shaped part. Only one set of forming mold and one set of cutting fixture are required in the forming process, which reduces the number of molds and fixtures, reduces the manufacturing cost of molds and fixtures, and reduces the cost of subsequent maintenance. The bulging process uses a rigid bulging method, which eliminates the need to seal the upper and lower ends of the conical tube blank. This avoids sealing failure and leakage caused by insufficient sealing strength, as well as interruption of the forming process, thus improving production efficiency. It also eliminates the need to press the pressure ring tightly against the upper end of the conical tube blank for sealing, allowing the allowance section to actively provide flowing material to the forming section. During the forming process, the material deforms from top to bottom. By reasonably setting the allowance section of the tapered tube blank and reasonably controlling the blank holder force, the material in the allowance section flows to the forming section to replenish the material, avoiding material accumulation at the bottom, controlling the thinning rate to within 15%, suppressing wrinkling and cracking in the allowance section, reducing the scrap rate of the tapered parts, and improving the stability of forming.

[0022] The conical part provided by this invention is formed according to the forming method of conical part. The final contour error of the conical part is no more than 1.5mm and the thinning rate is no more than 15%, which improves the stability of the forming of the conical part and ensures the forming quality of the formed conical part. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of the cone-shaped part provided in an embodiment of the present invention; Figure 2 This is a top view of the cone-shaped part provided in an embodiment of the present invention; Figure 3 The cone-shaped part provided in the embodiment of the present invention is along Figure 2 A sectional view cut by section AA in the image; Figure 4This is a schematic diagram of the structure of the fan-shaped blank provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the tapered tube blank provided in an embodiment of the present invention; Figure 6 This is a cross-sectional view of the tapered tube blank provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of a tapered tube blank placed in a concave mold according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the molding die provided in an embodiment of the present invention; Figure 9 This is a thinning rate cloud diagram of the part forming when the allowance section of the tapered tube blank provided in this embodiment of the invention is 110mm; Figure 10 This is a thinning rate cloud diagram of the part forming when the tapered tube blank is not provided with a allowance section, as provided in the embodiment of the present invention; Figure 11 This is a thinning rate cloud diagram of the part forming when the allowance section of the tapered tube blank is 140mm, as provided in the embodiment of the present invention. Figure 12 This is a thinning rate cloud diagram of the part forming when the allowance section of the tapered tube blank provided in this embodiment of the invention is 120mm; Figure 13 This is a thinning rate cloud diagram of the part forming when the allowance section of the tapered tube blank is 130mm, as provided in the embodiment of the present invention. Figure 14 This is a design schematic diagram of Scheme 1 when the taper α of the tapered tube blank provided in this embodiment of the invention is 50°; Figure 15 This is a thinning rate cloud diagram of the part forming when the taper α of the tapered tube blank provided in the embodiment of the present invention is 50° and Scheme 1 is selected; Figure 16 This is a schematic diagram of Scheme 2 when the taper α of the tapered tube blank provided in this embodiment of the invention is 50°; Figure 17 This is a thinning rate cloud diagram of the part forming when the taper α of the tapered tube blank provided in the embodiment of the present invention is 50° and Scheme 2 is selected; Figure 18 This is a design schematic diagram of Scheme 1 when the taper α of the tapered tube blank provided in this embodiment of the invention is 55°; Figure 19 This is a thinning rate cloud diagram of the part forming when the taper α of the tapered tube blank provided in the embodiment of the present invention is 55° and Scheme 1 is selected; Figure 20 This is a schematic diagram of Scheme 2 when the taper α of the tapered tube blank provided in this embodiment of the invention is 55°; Figure 21This is a thinning rate cloud diagram of the part formed when the taper α of the tapered tube blank provided in the embodiment of the present invention is 55° and Scheme 2 is selected; Figure 22 This is a design schematic diagram of the tapered tube blank provided in this embodiment of the invention when the taper α is 60°; Figure 23 This is a thinning rate cloud diagram of the part forming when the taper α of the tapered tube blank is 60°, as provided in the embodiment of the present invention. Figure 24 This is a design schematic diagram of Scheme 1 when the taper α of the tapered tube blank provided in this embodiment of the invention is 65°; Figure 25 This is a design schematic diagram of Scheme 2 when the taper α of the tapered tube blank provided in this embodiment of the invention is 65°; Figure 26 This is a thinning rate cloud diagram of the part formed when the taper α of the tapered tube blank provided in the embodiment of the present invention is 65° and Scheme 2 is selected; Figure 27 This is a design schematic diagram of Scheme 1 when the taper α of the tapered tube blank provided in this embodiment of the invention is 70°; Figure 28 This is a design schematic diagram of Scheme 2 when the taper α of the tapered tube blank provided in this embodiment of the invention is 70°; Figure 29 This is a thinning rate cloud diagram of the part forming when the taper α of the tapered tube blank provided in the embodiment of the present invention is 70° and Scheme 2 is selected; Figure 30 This is a cloud diagram showing the thinning rate of the part formed when the blank holder force of the blank holder ring is 50t, as provided in this embodiment of the invention. Figure 31 This is a part forming diagram when the blank holder force of the blank holder ring provided in this embodiment of the invention is 50t; Figure 32 This is a thinning rate cloud diagram of the part forming when the blank holder force of the blank holder ring is 100t, provided in the embodiment of the present invention; Figure 33 This is a part forming diagram when the blank holder force of the blank holder ring provided in this embodiment of the invention is 100t; Figure 34 This is a thinning rate cloud diagram of the part forming when the blank holder force of the blank holder ring provided in this embodiment of the invention is 150t; Figure 35 This is a cloud diagram showing the thinning rate of the part formed when the blank holder force of the blank holder ring is 200t, as provided in this embodiment of the invention. Figure 36 This is a cloud diagram showing the thinning rate of the part formed when the blank holder force of the blank holder ring is 300t, as provided in this embodiment of the invention. Figure 37This is a thinning rate cloud diagram of the part forming when the friction coefficient is controlled at 0.05 by setting a Teflon film between the pressure ring, the tapered tube blank and the die and coating it with graphite castor oil, as provided in the embodiments of the present invention. Figure 38 This is a thinning rate cloud diagram of the part forming when the friction coefficient is controlled at 0.125 by coating castor oil between the pressure ring, the tapered tube blank and the die according to the embodiment of the present invention. Figure 39 This is a thinning rate cloud diagram of the part forming process when the friction coefficient is controlled at 0.08 by coating graphite castor oil between the pressure ring, tapered tube blank and die according to the embodiment of the present invention. Figure 40 This is a thinning rate cloud diagram of part forming when a Teflon film is placed between the pressure ring, the tapered tube blank, and the die to control the friction coefficient at 0.1, as provided in the embodiments of the present invention. Figure 41 This is a thinning rate cloud diagram of part forming when the punch descends at a speed of 0.5 mm / s, as provided in an embodiment of the present invention. Figure 42 This is a thinning rate cloud diagram of part forming when the punch descends at a speed of 4 mm / s, as provided in an embodiment of the present invention. Figure 43 This is a contour plot of the thinning rate of the part formed when the punch descends at a speed of 5 mm / s, as provided in an embodiment of the present invention. Figure 44 This is a thinning rate cloud diagram of part forming when the punch descends at a speed of 2 mm / s, provided in an embodiment of the present invention. Figure 45 This is a thinning rate cloud diagram of part forming when the punch descends at a speed of 2.5 mm / s, as provided in an embodiment of the present invention. Figure 46 This is a contour map of the thinning rate of the part formed when the punch descends at a speed of 3 mm / s, as provided in an embodiment of the present invention.

[0024] In the picture: 1. Conical part; 11. Top opening; 12. Bottom opening; 13. Section line; 2. Tapered tube blank; 21. Allowance section; 22. Forming section; 221. Profile; 23. Upper end; 24. Lower bottom; L. Generatrix length; 3. Molding mold; 31. Cavity; 32. Pressure ring; 33. Punch; 34. Cavity; 341. Upper opening; 342. Lower opening; 35. Ejector block; 36. Pressure ring adapter plate; 37. Punch adapter plate. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings, not all of them.

[0026] This invention defines certain directional terms. Unless otherwise stated, the directional terms used, such as "up," "down," "left," "right," "inner," and "outer," are used for ease of understanding and therefore do not constitute a limitation on the scope of protection of this invention.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] like Figures 4-46 As shown, this embodiment provides a method for forming a conical part 1. The conical part 1 has an upper opening 11 and a lower opening 12, and the diameter D of the upper opening 11 is... 11 and the diameter D of the lower opening 12 12 The ratio is approximately 10:1, the height H of the conical part 1 is 400mm-500mm, and the diameter D of the upper opening 11 is... 11 The diameter D of the lower opening 12 is 450mm-550mm. 12 The cross-sectional line 13 of the conical part 1 is 40-55mm, and is a smooth, outwardly convex arc, including the following steps: Prepare a tapered tube blank 2. The tapered tube blank 2 has a connected allowance section 21 and a forming section 22. The allowance section 21 extends along the inclined direction of the profile 221 of the forming section 22, and the allowance section 21 faces the upward opening 11, that is, the allowance section 21 is connected to the large diameter end of the forming section 22. The forming section 22 of the tapered tube blank 2 is placed in the cavity 34 of the die 31, and the pressure ring 32 is pressed onto the remaining section 21 of the tapered tube blank 2, and a pressure force is applied to the pressure ring 32. The punch 33 descends and closes with the die 31 to perform rigid bulging. During the rigid bulging process, the blank holder force is configured to both suppress wrinkling of the allowance section 21 and allow the material of the allowance section 21 to flow to the forming section 22 to replenish the material until the punch 33 closes.

[0030] The forming method of the cone part provided by the present invention is an integral forming method with fewer processes and fewer welds, which improves the overall strength and reliability of the cone part 1. Only one set of forming mold 3 and one set of cutting fixture are required in the forming process, which reduces the number of forming mold 3 and cutting fixture, reduces the manufacturing cost of forming mold 3 and cutting fixture, and reduces the cost of subsequent maintenance. The bulging adopts a rigid bulging method, which eliminates the need to seal the upper and lower ends of the tapered tube blank 2. This avoids sealing failure and water leakage caused by insufficient sealing strength, as well as interruption of molding, thus improving production efficiency. It also eliminates the need to press the pressure ring 32 to the upper end of the tapered tube blank 2 for sealing, allowing the allowance section 21 to actively provide flowing material to the molding section 22. During the forming process, the material deforms from top to bottom. By reasonably setting the allowance section 21 of the tapered tube blank 2 and reasonably controlling the blank holder force, the material of the allowance section 21 flows to the forming section 22 to replenish the material, avoiding material accumulation at the bottom, controlling the thinning rate to within 15%, suppressing wrinkling and cracking of the allowance section 21, reducing the scrap rate of the tapered part 1, and improving the stability of the forming process.

[0031] Furthermore, in the step of preparing the tapered tube blank 2, the tapered tube blank 2 is formed by winding and welding a fan-shaped blank, such as... Figures 4-6 As shown, the tapered tube blank 2 has one axial weld. The shape of the sector-shaped blank is the unfolded shape of the tapered tube blank 2, and the size of the sector-shaped blank is determined by the size of the tapered tube blank 2. The tapered tube blank 2 has an upper port 23 and a lower port 24, and the diameter of the upper port 23 is D. 21 The diameter of the bottom opening 24 is D. 22 The generatrix length is L. Based on the fact that the tapered tube blank 2 is developed into a sector-shaped blank, the correspondence between the tapered tube blank 2 and the sector-shaped blank is obtained. Assuming the outer radius of the sector-shaped blank is R1, the inner radius is R2, and the central angle is θ, then: L = R1 - R2; R1×θ=π×D 21 ; R²×θ=π×D 22 ; After modification, we can obtain: R1=L×D 21 / (D 21 -D 22 ); (1) R2=L×D 22 / (D 21 -D 22 ); (2) θ=π×(D 21 -D 22 ) / L. (3) Furthermore, after preparing the tapered tube blank 2 and before placing the forming section 22 of the tapered tube blank 2 into the cavity 34 of the die 31, the process further includes the step of performing a vacuum solution treatment on the tapered tube blank 2. The vacuum solution treatment is to eliminate the residual welding stress of the weld of the tapered tube blank 2, improve the strength and plasticity of the weld, and reduce the risk of the weld cracking during the forming process.

[0032] Specifically, the specific parameters for vacuum solution treatment are determined based on the material and forming type of the tapered tube blank 2. In this embodiment, the material of the tapered tube blank 2 is GH3536, the forming type of the material is cold-rolled sheet, and the thickness is 1.0 mm (less than 3 mm). Therefore, the heating temperature for vacuum solution treatment is 1130℃-1170℃, the holding time is 8 min-12 min, and the cooling method is rapid cooling or water cooling.

[0033] Further, after placing the tapered tube blank 2 into the forming mold 3, as follows... Figures 7-8 As shown, the forming mold 3 includes a concave mold 31, a pressure ring 32, and a punch 33. A cavity 34 is formed inside the concave mold 31, with an upper opening 341 and a lower opening 342. The punch 33 can be pressed into the cavity 34. The conical surfaces of the punch 33 and the cavity 34 are adapted to the shape of the conical part 1. The conical surface of the conical tube blank 2 is divided into a allowance section 21 and a forming section 22, with the contact point between the conical tube blank 2 and the concave mold 31 as the boundary. There is an axial distance d between the forming section 22 and the lower opening 342 of the cavity 34. The axial distance d is set to avoid material accumulation at the bottom. Based on the positional relationship between the conical tube blank 2 and the cavity 34, and the relationship between the cavity 34 and the conical part 1, the dimensional relationship between the conical part 1 and the conical tube blank 2 can be established, as follows: Cavity 34 includes at least the conical part 1, meaning that the part formed by cavity 34 needs to allow for a cutting allowance for the conical part 1: D 31 =D 11 +△d 11 ; (4) D32 =D 12 +△d 12 ; (5) H1 = H + Δh; (6) In the formula, D 31 D is the diameter of the upper opening 341 of cavity 34. 11 Let Δd be the diameter of the upper opening 11 of the conical part 1. 11 For cavity 34, the cutting allowance reserved in diameter at the upper end of the conical part 1 is D. 32 D is the diameter of the lower opening 342 of cavity 34. 12 Let Δd be the diameter of the lower opening 12 of the conical part 1. 12 H1 is the cutting allowance reserved in diameter for the lower end of the conical part 1 in cavity 34, H is the height of cavity 34, H is the height of conical part 1, and Δh is the cutting allowance reserved in height direction for cavity 34 and conical part 1.

[0034] The height H of the conical part 1 and the cavity 34 are the cutting allowance △d reserved on the diameter of the lower end of the conical part 1. 12 Cavity 34 is the cutting allowance △d reserved on the diameter of the upper end of the conical part 1. 11 The relationship between them is derived from the variation law of the cross-sectional line 13 of the conical part 1.

[0035] Based on the positional relationship between the tapered tube blank 2 and the cavity 34, we can conclude that: D 22 =D 32 -△D; (7) D 21 =D 22 +2L×sin(α / 2); (8) cos(α / 2)=h / L; (9) h-L1×cos(α / 2)+d=H 1； (10) In the formula, D 22 D is the diameter of the bottom opening 24 of the tapered tube blank 2. 32 Let ΔD be the diameter of the lower opening 342 of cavity 34, and let ΔD be the diameter difference between the lower bottom opening 24 of tapered tube blank 2 and the lower opening 342 of cavity 34. 21 L is the diameter of the upper port 23 of the tapered tube blank 2, L is the generatrix length of the tapered tube blank 2, α is the taper of the tapered tube blank 2, L1 is the length of the allowance section 21, h is the height of the tapered tube blank 2, H1 is the height of the cavity 34, and d is the axial distance from the lower bottom opening 24 of the tapered tube blank 2 to the lower opening 342 of the cavity 34.

[0036] Establish the dimensional relationship between the conical part 1 and the conical tube blank 2 according to equations (4)-(10).

[0037] Furthermore, the contact surface between the pressure ring 32 and the allowance section 21 is an inclined surface, and the contact surface between the die 31 and the allowance section 21 is also an inclined surface, which facilitates the flow of material from the allowance section 21 to the forming section 22. The inclined setting of the allowance section 21, unlike the existing fully compressed flange section, allows the allowance section 21 to move between the die 31 and the pressure ring 32, facilitating the flow of material from the allowance section 21 to the forming section 22 and preventing cracking and wrinkling.

[0038] Furthermore, the forming mold 3 also includes a blank holder adapter plate 36 and a punch adapter plate 37. The blank holder adapter plate 36 is connected to the blank holder ring 32, and the punch adapter plate 37 is connected to the punch 33. The blank holder adapter plate 36 and the punch adapter plate 37 are respectively connected to the press to realize the independent movement between the blank holder ring 32 and the punch 33, so as to ensure the control of the downward movement of the punch 33 and the blank holder force of the blank holder ring 32 during the forming process.

[0039] Furthermore, the molding die 3 also includes an ejector block 35, which is disposed below the lower opening 342 of the cavity 34 and is used to eject the part from the cavity 34 after the part is formed.

[0040] Furthermore, when the tapered tube blank 2 is placed in the forming mold 3, the length L1 of the allowance section 21 is 120mm-130mm. This length L1 is not a simple process allowance, but rather a functional material replenishment area determined by the material flow rate. Simulations show that with the length L1 of the allowance section 21 being 120mm-130mm, the actual material flow rate during the forming process is 100mm-104mm. This provides continuous material replenishment to the profile 221 of the forming section 22, keeping the thinning rate below 15%, and also retains a 45mm-55mm upper end allowance after forming to compensate for the deviation between actual production and theoretical simulation.

[0041] If the length L1 of the allowance section 21 is less than 120mm, the allowance is small, the flow resistance is small, the early material replenishment effect is good, and the thinning rate of the part during the molding process is reduced. However, the allowance section 21 is quickly pulled into the cavity 34 of the die 31, and there is no material to replenish in the later stage of the flow, resulting in the incomplete surface 221 of the molding section 22 (missing material) or wrinkling and scrapping. The remaining allowance at the upper end is too small, resulting in a large deviation between the actual production and the theoretical simulation thinning rate. Figure 9As shown, the part thinning rate cloud diagram is shown when the length L1 of the allowance segment 21 is 110mm. The maximum thinning rate of the part during the forming process is 12.889%. Although the thinning rate is controlled below 15%, the allowance at the upper end after forming is 10mm. The upper end allowance meets the deviation of 5mm between actual production and theoretical simulation. After compensating for the deviation between actual production and theoretical simulation, the remaining allowance at the upper end is 5mm. The upper end remaining allowance is too small, resulting in an excessive deviation between the actual production and theoretical simulation thinning rate. The large diameter end of the forming segment 22 does not have an allowance segment 21, that is, no allowance is reserved at the end of the forming segment 22. The part thinning rate cloud diagram is shown below. Figure 10 As shown, the tapered tube blank 2 is directly pressed into the cavity 34 of the die 31 by the punch 33. During the forming process, the part is basically not thinned, the upper end of the part wrinkles, and the lower end is filled with material. If the length L1 of the allowance section 21 is greater than 130mm, the contact area between the pressure ring 32 and the allowance section 21 of the tapered tube blank 2 increases, the frictional resistance rises, hindering material flow and causing the thinning rate to increase to the point of not meeting the requirements. Figure 11 As shown, the part thinning rate cloud diagram during the forming process is when the length L1 of the allowance segment 21 is 140mm. The maximum thinning rate of the part during the forming process is 18.182%, which does not meet the requirement of controlling the thinning rate below 15%. The increase in the thinning rate leads to local necking or even fracture failure of the material. If the length L1 of the allowance segment 21 is within the range of 120mm-130mm, such as 120mm, the thinning rate cloud diagram during the part forming process is as follows: Figure 12 As shown, continuous material replenishment occurs during the molding process. The maximum thinning rate of the part during molding is 13.451%, which is within 15%. After molding, a 45mm allowance is retained at the top end. After compensating for the deviation between actual production and theoretical simulation, 40mm remains, ensuring that the molding quality of the part meets the requirements. For example, for a 130mm part, the thinning rate cloud diagram during the molding process is shown below. Figure 13 As shown, continuous material replenishment occurs during the molding process, and the maximum thinning rate of the parts during the molding process is 13.671%, which is within 15%. After molding, a 55mm allowance is retained at the top end. After compensating for the deviation between actual production and theoretical simulation, 50mm remains, ensuring that the molding quality of the parts meets the requirements.

[0042] Furthermore, the taper α of the tapered tube blank 2 is 60°-70°, and the diameter D of the lower opening 24 of the tapered tube blank 2 is... 22 The diameter D of the lower opening 342 of cavity 34 32 The diameter of the tapered tube blank 2 is 5mm-10mm smaller (i.e., ΔD = 5mm-10mm), and the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is 90mm-100mm. The taper α of the tapered tube blank 2 and the diameter D of the bottom opening 24 are also specified. 22The three geometric parameters—the axial distance d between the bottom opening 24 and the bottom opening 342 of the cavity 34, and the bottom opening 242 of the bottom opening 34—are not independent, arbitrary, or redundant variables. Instead, they are a set of multi-objective collaborative constraint parameters established based on extensive finite element simulations under rigid forming process conditions to solve specific material flow problems. Under the mutual collaborative constraints of the above three geometric parameters, the initial material volume at the lower end of the tapered tube blank 2 is precisely matched with the spatial volume at the bottom of the cavity 34. This ensures continuous material replenishment from the allowance section 21 to the surface 221 of the forming section 22, and also enables the orderly filling of the gap between the bottom opening 24 and the cavity 34 from the forming section 22. This avoids defects such as insufficient material, material accumulation, wrinkling, and breakage, ensuring that the thinning rate meets the requirements. Furthermore, it reserves a cutting allowance for subsequent finishing processes at the lower end of the formed part to ensure the dimensional accuracy of the lower opening 12 of the formed tapered part 1.

[0043] In this embodiment, the numerical range limitation of the aforementioned tapered tube blank 2 is not intended to define an optimal intermediate value, but rather a safe process window defined based on the material's physical properties. In this embodiment, the safe process window is relatively narrow for the specific material of the tapered part 1, and determining this window is not easy. Anyone skilled in the art who selects any value within this range must adhere to the original intention of solving the technical problem of precise material compensation. Furthermore, the three parameters mentioned above are mutually constrained and require simultaneous adjustment. Values ​​outside the numerical range of the three parameters of the tapered tube blank 2 will result in material shortage (functional failure) if below the lower limit, and material accumulation (manufacturing defect) if above the upper limit. This fully demonstrates that the numerical range of this embodiment has clear technical boundaries and industrial applicability, and is by no means an arbitrary design choice.

[0044] During the simulation and iterative verification process for the specific formed part—the cone part 1—in this embodiment, the above three parameters need to be adjusted simultaneously during the simulation. The simulation results during the simulation and iterative verification process are as follows: Figures 14-29 As shown, the specific process is as follows: When the taper α of the tapered tube blank 2 is fixed, there are two schemes for the design of the remaining two parameters: Scheme 1: Ensure that the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is at least 90mm, then determine whether the diameter difference ΔD between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is within the limit range, and check the forming condition of the part; Scheme 2: Ensure that the diameter difference ΔD between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is 5mm-10mm, then determine whether the axial distance d between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is within the limit range, and check the forming condition of the part.

[0045] When the taper α of the fixed tapered tube blank 2 is 50°, and Scheme 1 is selected for designing the tapered tube blank 2, as follows: Figure 14 As shown, the diameter D of the bottom opening 24 of the tapered tube blank 2 is... 22 The diameter D of the lower opening 342 of the cavity 34 is much larger than that of the cavity 34. 32 , Figure 15 The thinning rate cloud diagram is for the forming process. Due to the diameter D of the bottom opening 24 of the tapered tube blank 2, 22 If the diameter is too large, insufficient material will appear after molding, and the thinning rate will be greater than 15%; when the taper α of the fixed conical tube blank 2 is 50°, if Scheme 2 is selected for designing the conical tube blank 2, such as Figure 16 As shown, the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is negative, indicating no blank flow space. Figure 17 The thinning rate cloud diagram shows that the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is negative. During the forming process, the lower end is blocked, which restricts the flow of material at the upper end, resulting in the thinning rate increasing to 16.896%, which is greater than the required 15%.

[0046] When the taper α of the fixed tapered tube blank 2 is 55°, and Scheme 1 is selected for designing the tapered tube blank 2, as follows: Figure 18 As shown, the diameter D of the bottom opening 24 of the tapered tube blank 2 is... 22 The diameter D of the lower opening 342 of the cavity 34 is much larger than that of the cavity 34. 32 , Figure 19 The thinning rate cloud diagram is for the forming process. Due to the diameter D of the bottom opening 24 of the tapered tube blank 2, 22 If the diameter is too large, insufficient material will appear after molding, and the thinning rate will be greater than 15%; when the taper α of the fixed conical tube blank 2 is 55°, if Scheme 2 is selected for designing the conical tube blank 2, such as Figure 20 As shown, the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is 48.3 mm, which is lower than the lower limit of the specified range, indicating insufficient space for blank flow. Figure 21 The thinning rate cloud diagram shows that because the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is lower than the lower limit of the specified range, the space for material flow at the lower end is insufficient during the forming process, which restricts material flow at the upper end, resulting in a thinning rate increase to 18.685%, which is greater than the required 15%.

[0047] When the taper α of the fixed tapered tube blank 2 is 60°, regardless of whether Scheme 1 or Scheme 2 is selected for designing the tapered tube blank 2, as follows: Figure 22 As shown, all three parameters are within the specified range. Figure 23 The thinning rate cloud map shows that the bottom margin of the formed part is 5mm, which is sufficient for laser cutting, and the maximum thinning rate is 13.991%, which meets the requirements for the thinning rate.

[0048] When the taper α of the fixed tapered tube blank 2 is 65°, when designing the tapered tube blank 2 using Scheme 1, the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is ensured to be 100mm. Figure 24 As shown, the diameter D of the bottom opening 24 of the tapered tube blank 2 is... 22 The diameter D of the lower opening 342 of the cavity 34 is much smaller than that of the cavity 34. 32 The diameter D of the bottom opening 24 of the tapered tube blank 2 22 The taper is essentially zero; the bottom opening 24 of the tapered tube blank 2 is basically closed and cannot be formed. When the taper α of the fixed tapered tube blank 2 is 65°, if Scheme 2 is selected for designing the tapered tube blank 2, such as... Figure 25 As shown, the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is 129 mm. Figure 26 The thinning rate cloud diagram for the forming process shows that the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is too large, resulting in an excessive flow space. During the forming process, the flow at the upper end increases, causing the thinning rate to increase to 15.921%, which is greater than the required 15%. As a result, the bottom allowance of the formed part is too small, and the actual production deviation from the theoretical allowance is insufficient.

[0049] When the taper α of the fixed tapered tube blank 2 is 70°, and Scheme 1 is selected for designing the tapered tube blank 2, as follows: Figure 27 As shown, it is impossible to design a diameter D that satisfies the bottom opening 24 of the tapered tube blank 2. 22 The diameter D of the lower opening 342 of cavity 34 is smaller than that of cavity 34. 32 The scheme; when the taper α of the fixed tapered tube blank 2 is 70°, when designing the tapered tube blank 2 using scheme two, such as Figure 28 As shown, the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is 162 mm. Figure 29 The thinning rate cloud diagram for forming shows that the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is too large, resulting in an excessive flow space. During the forming process, the flow at the upper end increases, causing the thinning rate to increase to 15.009%, which is basically at the limit of the required thinning rate. After forming, there is basically no allowance at the bottom of the part. The actual production deviation from the theoretical allowance is insufficient, which will cause the originally designed forming path to collapse due to minor real-world interference, resulting in batch scrapping of parts, damage to the mold, and making the entire process unapprovable for mass production.

[0050] The simulation and iterative verification process of the specific forming part - cone part 1 in this embodiment revealed the following physical laws, and based on these laws, the optimal process parameters were established: Determination of the taper α of the tapered tube blank 2: Simulation results show that when the taper α of the tapered tube blank 2 exceeds 60° (e.g., increases to 65° or 70°), due to the excessively steep generatrix of the tapered tube blank 2, the circumferential compressive stress increases sharply during the downward flow of the material, leading to severe instability and wrinkling of the sidewall of the tapered tube blank 2, making it impossible to form the intended smooth outward convex arc. Conversely, if the taper α of the tapered tube blank 2 is less than 60°, due to the excessively gentle generatrix of the tapered tube blank 2, the material supply in the middle region is insufficient, forcing this region to produce a thinning rate exceeding the limit due to excessive stretching, directly causing tensile fracture of the sidewall of the formed part. When the taper α of the tapered tube blank 2 is 60°, the generatrix of the tapered tube blank 2 can achieve a precise balance between material flow compression and tensile compensation, which is the critical optimal value to ensure the forming quality of the outward convex curve.

[0051] In existing technologies, when using flexible bulging for bulging, the taper of the conical tube blank is a fixed value. The taper depends on the diameters of the upper opening 11 and lower opening 12 of the conical part 1 and its overall height H. That is, the generatrix of the conical tube blank must pass through the upper and lower endpoints of the conical part 1, and there is no distance between the bottom of the conical tube blank and the bottom of the cavity 34 to ensure end sealing. In existing technologies, the taper of the conical tube blank depends on the diameters of the upper opening 11 and lower opening 12 of the conical part 1 and its overall height H. When the ratio of the diameters of the upper opening 11 to the lower opening 12 is large, the generatrix of the conical tube blank is too steep. During the downward flow of the material, the circumferential compressive stress increases sharply, leading to severe instability and wrinkling of the sidewalls of the conical tube blank, making it impossible to form the intended smooth, convex arc. In other words, based on the structural characteristics of the conical part 1 to be formed in this embodiment, using flexible bulging results in severe instability and wrinkling of the sidewalls of the conical tube blank, causing forming failure.

[0052] Determination of the diameter difference ΔD between the lower opening 24 of the tapered tube blank 2 and the lower opening 342 of the cavity 34: Simulation results show that the 5mm-10mm limit is not arbitrarily selected; its upper and lower limits correspond to specific physical failure critical points in rigid forming. If the diameter difference ΔD between the lower opening 24 of the tapered tube blank 2 and the lower opening 342 of the cavity 34 is less than 5mm, or even if the diameter D of the lower opening 24 of the tapered tube blank 2 is less than 5mm, then the diameter difference ΔD between the lower opening 24 and the lower opening 342 of the cavity 34 is less than 5mm. 22 The diameter D of the lower opening 342 of cavity 34 is greater than that of cavity 34. 32If the material flow is abnormal, the material at the bottom opening 24 of the tapered tube blank 2 cannot be effectively contained at the bottom of the mold 34 during the initial downward movement of the punch 33. A large amount of material is forced to "flow backward" to the upper mold surface. This abnormal material flow will cause obvious material loss in the lower area of ​​the formed part, i.e., "material shortage", which will damage the geometric integrity of the lower end of the part. If the diameter difference ΔD between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is greater than 10mm, the geometric difference between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 will be too large. When the punch 33 moves to the bottom, the excess material at the lower end of the tapered tube blank 2 cannot be dispersed by the deep drawing process and can only accumulate in the bottom area. This excessive accumulation will form serious material accumulation and stacking defects under rigid pressing force.

[0053] By controlling the diameter difference ΔD between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 within the range of 5mm-10mm, the initial material volume at the bottom of the tapered tube blank 2 can be precisely matched with the spatial volume at the bottom of the cavity 34, thereby achieving orderly filling of the material into the surface 221 and avoiding the aforementioned defects of "insufficient material" or "material piling".

[0054] Determination of the axial distance d between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34: Simulation results show that when the axial distance d between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is greater than 100mm (e.g., 129mm or 162mm), the blank flow space is too large, and the material flow at the upper end increases during the forming process, resulting in the thinning rate increasing to the limit value of the required thinning rate. After forming, there is basically no allowance at the bottom of the part. The actual production deviation from the theoretical allowance is insufficient, which will cause the originally designed forming path to collapse due to minor real-world interference, resulting in batch scrapping of parts, damage to the mold, and the inability to approve the entire process for mass production. Conversely, if the axial distance d between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is less than 90mm (e.g., 48.3mm or less), the blank flow space is insufficient, and the material blockage occurs at the lower end during the forming process, restricting the material flow at the upper end, resulting in an increased thinning rate. The axial distance d between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34 is kept within the range of 90mm-100mm so that the tapered tube blank 2 can achieve a precise balance between sufficient allowance and material accumulation at the bottom of the formed part.

[0055] Traditional flexible bulging processes require a zero-distance seal between the bottom of the tapered tube blank and the bottom of the cavity 34 to prevent hydraulic leakage. This embodiment, however, employs a rigid bulging process, eliminating the need for a sealed environment during molding. This overcomes the limitations of traditional methods by creatively pre-reserving an axial distance between the bottom opening 24 of the tapered tube blank 2 and the bottom opening 342 of the cavity 34. This axial distance serves the following purposes: Function 1: Material buffering during the forming stage. During the rigid forming process, when the billet material flows downward along the convex curved surface of the sidewall and squeezes the bottom of the cavity 34, this axial distance acts as a physical buffer, which can effectively release the impact stress of the descending material and prevent local material accumulation or rigid interference caused by excessive extrusion; Function 2: Cutting allowance for subsequent processes. This axial distance means that the lower end of the formed part will have a process tail section that does not participate in the final structural load-bearing. Since rigid forming is often accompanied by slight springback or local deformation at the rounded corners of the mold, retaining this extended axial distance can serve as a cutting allowance for subsequent finishing processes. By mechanically removing this excess bottom end, the boundary dimension error during the forming process can be effectively eliminated, ultimately obtaining a lower opening 12 of the conical part 1 with precise contours and regular edges.

[0056] Furthermore, the blank holder force of the blank holder ring 32 is 100t-200t to achieve a balance between suppressing wrinkling and ensuring material flow. In the simulation and iterative verification process of adjusting the blank holder force of the blank holder ring 32 in this embodiment, it was found that there is a strong coupling relationship between the blank holder force of the blank holder ring 32 and the dimensions of the tapered tube blank 2. The blank holder force of the blank holder ring 32 has a specific process window; exceeding this process window will lead to different failure modes: If the blank-pressing force of the blank-pressing ring 32 is less than 100t (e.g., 50t, see...) Figures 30-31 If the blanking force is too low, the friction between the excess section 21 of the tapered tube blank 2 and the blank holder 32 will be insufficient. The material will easily become unstable under tangential compressive stress, leading to irreversible wrinkling defects at the upper end of the part. Simultaneously, the lower end of the part will locally thicken to 30%, while other areas will have a thickness of approximately 10%, indicating a severe inconsistency in wall thickness within this area, resulting in material accumulation and wrinkling. This is because insufficient blank holder force will cause excessive material to flow into the bottom of the cavity 34 during the initial molding stage. Due to the small diameter of the bottom opening 24 and limited flow space, excess material has nowhere to go and ultimately accumulates at the bottom of the cavity 34, causing the part to be scrapped. If the blank holder force of the blank holder 32 is higher than 200t (e.g., 300t, see...), the material will be damaged. Figure 36 The remaining section 21 is completely locked by the pressure ring 32 and the die 31, which drastically increases the flow resistance. The material cannot flow into the cavity 34, meaning that the material cannot be fed into the surface 221 of the forming section 22. The forming process degenerates into pure bulging, and the tapered tube blank 2 is thinned only by its own limited plastic deformation capacity to cover the increased area of ​​the surface 221, thus increasing the maximum thinning rate of the part. Figure 36 The thinning rate is 18.440%, which does not meet the requirement that the thinning rate should be controlled within 15%. Cracking has occurred in the heat-affected zone of the weld. In addition, excessive blank holder force will aggravate the friction between the tapered tube blank 2 and the forming mold 3, increasing the risk of mold wear and scratches on the surface of the parts.

[0057] Conversely, when the blank holder force is controlled within the range of 100t~200t (excluding the end value), such as Figures 32-35 As shown, when the blank holder force is 100t, although in the simulation... Figure 33 The upper part of the display part shows slight wrinkling, but this wrinkling is reversible. When the concave mold 31 and the convex mold 33 in the forming mold 3 are fully closed, the convex mold 33 can flatten the slight wrinkling, and the thinning rate meets the requirements, with no material accumulation or cracking. When the blank holder force is 150t, the thinning rate meets the requirements, with no material accumulation or cracking. When the blank holder force is 200t, there is no material accumulation or cracking, but the thinning rate does not meet the requirements. The reasonable range of blank holder force can ensure that the material flows continuously from the allowance section 21 into the cavity 34 to replenish the material, while providing sufficient frictional constraint force to suppress wrinkling defects during the forming process. In order to ensure the quality of forming, the process should be designed to ensure that wrinkling does not occur throughout the process and that the thinning rate meets the requirements. When the blank holder force is 100t or 200t, the dimensions of the tapered tube blank 2 can be finely adjusted to avoid wrinkling throughout the process and ensure that the thinning rate meets the requirements.

[0058] Therefore, the blank holder force of 100t-200t is a non-obvious range in which a balance is achieved between suppressing wrinkling and ensuring material flow.

[0059] There exists a reasonable range for the blank holder force, which cannot be too small (otherwise wrinkling and stacking) nor too large (otherwise excessive thinning and cracking). Through extensive nonlinear finite element simulations and forming experiments, it has been found that the above-mentioned reasonable range is not a fixed point value, but a range related to the dimensions of the tapered tube blank 2.

[0060] Specifically, when the length L1 of the allowance section 21 of the tapered tube blank 2 is between 120mm and 130mm, the taper α of the tapered tube blank 2 is 60°-70°, and the diameter D of the bottom opening 24 of the tapered tube blank 2 is... 22 The diameter D of the lower opening 342 of cavity 34 32 When the diameter of the tapered tube blank 2 is 5mm-10mm (i.e., ΔD=5mm-10mm) and the axial distance d from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34 is 90mm-100mm, controlling the blank holder force within the range of 100t~200t ensures that the material continuously flows from the allowance section 21 into the cavity 34 for replenishment, while also providing sufficient frictional constraint to suppress wrinkling defects during the forming process. If the size of the tapered tube blank 2 exceeds the limit range, even if the blank holder force is adjusted within the limit range, it is impossible to simultaneously meet the forming requirements of a thinning rate ≤15% and no wrinkling. That is, when adjusting the parameters, the strong coupling relationship between the blank holder force of the blank holder ring 32 and the size of the tapered tube blank 2 cannot be ignored.

[0061] By coordinating the blanking force with the dimensions of the tapered tube blank 2, this embodiment achieves overall optimization of various parameters. While ensuring continuous material replenishment and controlling the thinning rate within 15%, it effectively suppresses wrinkling defects during the forming process, thereby obtaining an integrally formed tapered part 1 with uniform wall thickness and high surface accuracy.

[0062] Furthermore, the friction coefficients of the contact surfaces between the blank holder 32 and the tapered tube blank 2, and between the die 31 and the tapered tube blank 2, are both 0.08-0.1, achieved by applying lubricant to the contact surfaces. This friction coefficient, in conjunction with the blank holder force of 100t-200t, jointly controls the material flow rate and flow volume. During the simulation and iterative verification process of adjusting the friction coefficient, it was found that: If the coefficient of friction is too low (e.g., 0.05), it can be achieved by placing a Teflon film on the contact surface and coating it with graphite castor oil. Figure 37 As shown), the lower end of the part thickens to 16.409%, while other areas are around 8%, indicating a severe inconsistency in wall thickness within this region, resulting in material buildup and wrinkling. This is because the pressure ring 32 cannot provide sufficient frictional constraint for the allowance section 21, leading to excessive material flow. The tapered tube blank 2 slips during the material flow process, posing a risk of material buildup and wrinkling at the bottom. The thinning rate should be controlled within 15%. If the coefficient of friction is too high (e.g., 0.125), it can be achieved by coating the contact surface with castor oil, such as... Figure 38 As shown in the figure, the thinning rate increased to 19.240%, which does not meet the requirements. This is because the friction coefficient is too high, the material flow resistance is too large, the material flow is too small, the thinning is too large, and the thinning rate exceeds the standard.

[0063] Conversely, friction coefficients in the range of 0.08-0.1 (e.g.) Figures 39-40 As shown in the figure, the thinning rate meets the requirements, and there is no risk of material wrinkling due to accumulation. The coefficient of friction is within a reasonable range, which allows the blank holder force and friction force to form controllable material flow damping. This is one of the key conditions for achieving dynamic material replenishment in the 21st margin section.

[0064] Preferably, graphite castor oil is applied to both the contact surface between the pressure ring 32 and the tapered tube blank 2, and the contact surface between the die 31 and the tapered tube blank 2, to control the friction coefficient at approximately 0.08. This is because controlling the friction coefficient to approximately 0.1 requires attaching a Teflon film to both the contact surface between the pressure ring 32 and the tapered tube blank 2, and the contact surface between the die 31 and the tapered tube blank 2, which is more complex than applying graphite castor oil. For ease of operation, graphite castor oil is applied to both the contact surface between the pressure ring 32 and the tapered tube blank 2, and the contact surface between the die 31 and the tapered tube blank 2, allowing the pressure force and friction to create controllable material flow damping, ensuring precise dynamic material replenishment in the allowance section 21.

[0065] The setting of the friction coefficient and the setting of the blank holder force are coupled. When the blank holder force is not within the specified range, even if the friction coefficient is adjusted within the specified range, there is still a risk of material wrinkling and the thinning rate is difficult to control within 15%.

[0066] Furthermore, the downward speed of the punch 33 is set to 2mm / s-3mm / s. This downward speed is coupled with the blank holder force and the coefficient of friction to control the material flow rate of the allowance section 21, ensuring precise dynamic material replenishment of the allowance section 21. Outside this speed range, the part failure mode undergoes a qualitative change: When the downward speed of punch 33 is less than 2 mm / s (e.g., 0.5 mm / s, such as...) Figure 41 When the cone tube blank 2 is in prolonged high-pressure contact with the forming mold 3 (as shown), the accumulation of frictional heat causes scratches on the surfaces of both the cone tube blank 2 and the forming mold 3, resulting in low production efficiency and a thinning rate slightly higher than 15%. When the downward speed of the punch 33 is higher than 3 mm / s (e.g., 4 mm / s and 5 mm / s, as shown), the production efficiency is too low, and the thinning rate is slightly higher than 15%. Figures 42-43 As shown), due to the high deformation resistance of the high-temperature alloy and the extreme taper ratio (approximately 10:1), high-speed deformation leads to a sudden increase in local stress. The tapered tube blank 2 does not have enough time to redistribute stress through plastic flow, making the part prone to instantaneous cracking. At the same time, after the forming mold 3 is unloaded, the springback of the part increases, the dimensions deteriorate, and the forming mold 3 experiences large load impact vibration. As a thin-walled part, the tapered part 1 is prone to impact ripples and bulges. When the downward speed of the punch 33 is 2mm / s-3mm / s (e.g., 2mm / s, 2.5mm / s, and 3mm / s, such as...), Figures 44-46 As shown in the figure, the thinning rate is slightly higher than 15%, but it can be reduced to within 15% by adjusting other parameters. Therefore, 2mm / s-3mm / s is a specific process window to avoid the contradictory failure mode of cracking and scratching while taking into account production efficiency.

[0067] The length L1 (120mm-130mm) of the aforementioned allowance section 21, the taper α (60°-70°) of the tapered tube blank 2, and the diameter D of the bottom opening 24 of the tapered tube blank 2 are all specified. 22 The diameter D of the lower opening 342 of cavity 34 32 The difference (5mm-10mm), the axial distance d (90mm-100mm) from the bottom opening 24 of the tapered tube blank 2 to the bottom opening 342 of the cavity 34, the blank holder force (100t-200t), the coefficient of friction (0.08-0.1), and the downward speed of the punch 33 (2mm / s-3mm / s) constitute a mutually coupled forming parameter system.

[0068] In this system, the length L1 of the allowance section 21 determines the total amount of material replenishment, the blank holder force and the coefficient of friction jointly determine the material flow rate, the axial distance d determines the bottom material space of the cavity 34, and the downward speed of the punch 33 determines the deformation strain rate. Adjusting any parameter independently of this system will disrupt the material flow-replenishment balance: for example, even if the blank holder force is 150t (within the range of 100-200t), if the length L1 of the allowance section 21 is 110mm, the material replenishment will be exhausted prematurely, resulting in insufficient material in the later stages of part forming, leading to a lack of material. Therefore, this parameter system is a non-obvious collaborative design for the integral forming of a thin-walled conical part 1 with a large taper.

[0069] Furthermore, the inner diameter of the pressure ring 32 is 0.2 mm larger than the outer diameter of the punch 33, so that the inner diameter of the pressure ring 32 plays a certain guiding role in the downward movement of the punch 33.

[0070] In the simulation, the mesh of the tapered tube blank 2 was initially set to 4 times the material thickness. This is because the formed tapered part 1 does not have a radius of less than R4. The mesh of the tapered tube blank 2 was enlarged during the simulation to speed up the simulation, thereby accelerating the design process and shortening the forming cycle.

[0071] After the molding die 3 is closed, the following steps are also included: When the molding die 3 opens, the ejector block 35 lifts up the molded part, making it easy to remove the molded part from the cavity 34; The upper and lower ends of the formed part are cut to obtain the cone part 1.

[0072] Using the forming method for the conical part provided in this embodiment, three parts were produced in the first batch and five parts in the second batch, all of which were qualified parts. The actual thinning rate, measured by an ultrasonic thickness gauge, was approximately 12%, which passed inspection. The diameter of the upper opening 11 of the conical part 1 passed inspection, and the final contour error of the conical part 1 was 1.5 mm, which passed inspection by the clamping plate. This demonstrates that the forming method for the conical part provided in this embodiment is effective and improves the pass rate of forming.

[0073] This embodiment also provides a conical part 1, which is formed according to the forming method of conical part 1. The final contour error of the conical part 1 is no more than 1.5mm and the thinning rate is no more than 15%, which improves the stability of the forming of the conical part 1 and ensures the forming quality of the formed conical part 1.

[0074] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for forming a conical part, the conical part (1) having an upper opening (11) and a lower opening (12), wherein the diameter D of the upper opening (11) is... 11 and the diameter D of the lower opening (12) 12 The ratio is 10:1, the cone part (1) is 400mm-500mm, and the diameter D of the lower opening (12) is... 12 The diameter is 40-55mm, and the cross-sectional line (13) of the conical part (1) is a smooth, outwardly convex arc. Its characteristic is that... Includes the following steps: Prepare a tapered tube blank (2), the tapered tube blank (2) having a reserve section (21) and a forming section (22), the reserve section (21) extending along the inclined direction of the profile (221) of the forming section (22), and the reserve section (21) being connected to the large diameter end of the forming section (22); The forming section (22) of the tapered tube blank (2) is placed in the cavity (34) of the die (31), and the blank holder (32) is pressed onto the remaining section (21) of the tapered tube blank (2), and a blank holder force is applied to the blank holder (32). The punch (33) descends and closes with the die (31) to perform rigid bulging. During the rigid bulging process, the blank holder force is configured to both suppress wrinkling of the allowance section (21) and allow the material of the allowance section (21) to flow to the forming section (22) for replenishment until the punch (33) closes.

2. The method for forming a conical part according to claim 1, characterized in that, The length L1 of the margin segment (21) is 120mm-130mm.

3. The method for forming a conical part according to claim 2, characterized in that, The taper α of the tapered tube blank (2) is 60°-70°, and the diameter D of the bottom opening (24) of the tapered tube blank (2) is... 22 The diameter D of the lower opening (342) of the cavity (34) is greater than that of the cavity (34). 32 The diameter is 5mm-10mm smaller, and the axial distance d from the bottom opening (24) of the tapered tube blank (2) to the bottom opening (342) of the cavity (34) is 90mm-100mm.

4. The method for forming a conical part according to any one of claims 1-3, characterized in that, The blank holder force is 100t-200t.

5. The method for forming a conical part according to claim 4, characterized in that, The friction coefficients of the contact surfaces of the pressure ring (32) and the tapered tube blank (2) and the die (31) and the tapered tube blank (2) are both 0.08-0.

1.

6. The method for forming a conical part according to claim 5, characterized in that, The contact surfaces of the pressure ring (32) and the tapered tube blank (2) and the contact surfaces of the die (31) and the tapered tube blank (2) are coated with graphite castor oil.

7. The method for forming a conical part according to claim 6, characterized in that, The downward speed of the punch (33) is 2 mm / s-3 mm / s. The downward speed of the punch (33) is coupled with the blank holder force and the coefficient of friction to control the material flow rate of the allowance section (21).

8. The method for forming a conical part according to claim 1, characterized in that, The inner diameter of the pressure ring (32) is 0.2 mm larger than the outer diameter of the punch (33).

9. The method for forming a conical part according to claim 1, characterized in that, After preparing the tapered tube blank (2), before placing the forming section (22) of the tapered tube blank (2) into the cavity (34) of the die (31), the step of vacuum solution treatment of the tapered tube blank (2) is also included.

10. A conical part, characterized in that, The cone part (1) is formed by the forming method according to any one of claims 1-9, and the final contour error of the cone part (1) is not greater than 1.5 mm and the thinning rate is not greater than 15%.

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