Thin-walled conical part forming method and one-step flanging forming die thereof

Abstract

The present invention discloses a method for forming thin-walled conical parts and a one-time flanging forming mold thereof, wherein the forming method is to draw the blank into a cylindrical part with a flange edge, and then flanging to form a conical part, wherein the cylindrical diameter of the cylindrical part is 1 to 1.1 times the diameter of the cone bottom of the conical part. During the flanging forming process, the height of the cylindrical part is designed based on the neutral layer length of the conical part, so that the conical surface suspended area of ​​the conical part is formed by tensile deformation. This forming method changes the deformation mode of the conical surface suspended area from traditional compression deformation to tensile deformation, thereby avoiding the possibility of wrinkling from the source. The forming mold can ensure that the part is symmetrical and uniform when flanging by accurately positioning the cylindrical part, realizing one-time precise forming of the conical part, and effectively avoiding the wrinkling and cracking problems of traditional forming.

Description

Technical Field

[0001] The present invention relates to the technical field of thin-walled parts forming, in particular to a thin-walled conical part forming method and a one-time flanging forming die thereof. Background Art

[0002] In the mechanical field, when forming thin-walled conical parts, for example, thin-walled conical parts with a wall thickness of about 0.6 mm and a cone angle of about 16° are processed, wrinkles are easily formed during the deep drawing process due to the presence of the suspended area of ​​the cone surface (the middle wall area excluding the flange edge and the cone bottom), and the quality is unstable. Regardless of whether a hard die is used for single or multiple deep drawing, or liquid filling deep drawing is used, the problem of wrinkles in the suspended area will eventually exist.

[0003] Instructions attached Figure 5 The figure shows the forming process of another thin-walled conical part, which is drawn using the rapid deep drawing method. According to the size example given in the figure, the first process is to draw a round blank with a diameter of 325mm into a cylindrical part with an inner diameter of 178mm; the second process is to draw a cylindrical part with a diameter equal to the average diameter of the conical part and a height equal to the height of the conical part. Figure 5 Figure a in Figure 1. In order to ensure good plasticity of the material, intermediate annealing is performed after each drawing; the third process directly presses the cylindrical part into a conical part, such as Figure 5 Figure b in .

[0004] The cone forming process of the above-mentioned cone part is as follows Figure 6 As shown in the figure, when the punch moves downward and just contacts the cylindrical blank with a flange, the blank is automatically centered under the guidance of the cone surface of the punch; the punch continues to descend, and the blank begins to deform simultaneously in areas A and B under the action of pressure. Under the action of pressure F, the material in area A flows upward along the inclined surface of the die in the direction of the arrow, and at the same time, the material in area B flows downward in the direction of the arrow. The deformation is equivalent to the process of flanging; when the punch reaches the bottom dead point, the conical part is pressed into shape.

[0005] Since the diameter of the material in area A decreases during deformation and is in a compressive stress state, and the downward pressure of the material in area B is applied to the side wall of the part, the material will become unstable and wrinkle when it is thin, making it impossible to achieve rapid and high-quality forming of such thin-walled conical parts with uniform wall thickness.

[0006] Patent publication number CN101733338A discloses a process for forming ultra-deep tapered thin-walled parts, and the process steps are as follows: (1) Blanking and punching: After the surface of a low-carbon steel strip is coated with lubricating oil, it is placed in a blanking and punching die with a pressure ring for punching. The tensile coefficient representing the degree of deep deformation of the workpiece, that is, the hole diameter d after blanking and punching ÷ the blanking diameter D, is 0.48 to 0.5, and the bottom radius of the hole r = (d-d1) × 3 ÷ 2; (2) Thinning Drawing: After blanking and punching, the workpiece surface is coated with lubricating oil and then placed in a thinning and drawing die for thinning and drawing. The diameter of the hole after thinning and drawing is equal to the inner diameter of the large end of the finished tapered hole, and the wall thickness is equal to the wall thickness of the finished product. At the same time, the thinning and stretching coefficient, that is, the wall thickness after thinning and drawing t′ ÷ the wall thickness before thinning and drawing t, is within the range of 0.75 to 0.8, and the bottom fillet r1 = (d1-d2) ÷ 2; (3) Notching: The workpiece is notched on the machine tool. The volume of the workpiece after notching is equal to The finished product has the same volume, and the incision length is converted according to the volume. The margin before the incision is 2mm~4mm; (4) Three consecutive tapers: After the workpiece surface is coated with lubricating oil after the incision, it is placed in the taper die for the first, second and third tapers. The tensile coefficient of the deformed part of the workpiece each time is controlled to be 0.75~0.8, that is, the small end hole diameter after this taper ÷ the hole diameter before deep drawing. The angle of the tapered hole and the inner diameter of the large end of the workpiece are the same as those of the tapered hole of the finished product. The transition radius between the small end of the tapered hole and the cylindrical hole is approximately equal to twice the cylindrical hole diameter of this taper. The bottom radius R value is half of the difference between the hole diameter before taper and the hole diameter after taper; (5) Oxygen-free annealing: The workpiece after three tapers is placed in a vacuum furnace, heated to 500℃~550℃, kept warm for 1 hour, and then taken out of the furnace after cooling to room temperature; (6) Continue tapering, and the process conditions are controlled the same as the first, second and third tapers until the specified shape and size of the product are obtained. Its characteristic is that the large-end tapered hole is formed first by taper pulling, and the small-end cylindrical hole diameter is gradually reduced, and combined with oxygen-free annealing treatment in the middle, the problem of the difficulty in forming ultra-deep tapered thin-walled parts is solved; the workpiece tube wall is thinned and deep-drawn before taper pulling, and the subsequent process utilizes the local thinning characteristics of the workpiece bottom fillet during taper pulling to gradually reduce the small-end cylindrical hole diameter, so that the workpiece wall thickness changes evenly.

[0007] The above patent involves a forming process for improving the uniformity of the wall thickness of thin-walled conical parts, but the forming process is complicated and the entire process is formed by deep drawing. The conical surface needs to be drawn multiple times. Although it can reduce wrinkling defects to a certain extent, it still cannot eliminate the wrinkling phenomenon and cannot quickly form conical parts. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for forming thin-walled conical parts that can effectively prevent instability and wrinkling during the forming process and can be formed quickly, in view of the defects of the existing technology.

[0009] The present invention also provides a one-time flanging forming die for realizing the above-mentioned thin-walled conical part forming method.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for forming thin-walled conical parts comprises drawing a blank into a cylindrical part with a flange edge, and then flanging the part to form the conical part. The diameter of the cylindrical part is 1 to 1.1 times the diameter of the cone base of the conical part. During the flanging process, the height of the cylindrical part is designed based on the neutral layer length of the conical part, so that the suspended area of ​​the cone surface of the conical part is formed by stretching deformation.

[0012] Furthermore, the cylindrical diameter of the cylindrical member is 1 times the diameter of the cone bottom of the conical member.

[0013] Furthermore, the principle for determining the height H of the cylindrical part is: define the diameter of the cone mouth of the conical part including the flange fillet as D1, the diameter of the cone bottom as D2, select the diameter D1 position on the flange edge of the cylindrical part, and then the neutral layer length from the position to the end of the cylindrical bottom fillet is equal to the neutral layer length from the cone diameter D1 to the end of the cone bottom fillet.

[0014] Furthermore, the number of deep drawing operations is determined according to the bottom diameter of the conical part and the unfolded size of the cylindrical part.

[0015] Furthermore, the drawing operation adopts hard die drawing.

[0016] Furthermore, the drawing operation adopts liquid filling deep drawing.

[0017] A one-time flanging forming die used in the above-mentioned thin-walled conical part forming method includes a female die and a male die. The male die is provided with a male die, a push rod, a pressure ring and a positioning block. The push rod passes through the male die and is connected to the pressure ring. The pressure ring can be controlled to move by the push rod. The positioning block is detachably arranged on the top of the male die. The positioning block is controlled by an elastic control part to move away from the male die along the axial direction of the mold and gradually reset as the female die and the male die are closed. The elastic control part passes through the male die.

[0018] Furthermore, the elastic control part includes a limiting rod connected to the positioning block and a spring sleeved on the outer circumference of the limiting rod.

[0019] Furthermore, the limiting rod is a limiting bolt, and the positioning block is provided with a threaded hole adapted to the limiting bolt.

[0020] Furthermore, when the cylindrical part is placed on the mold for flanging operation, the flange edge of the cylindrical part is attached to the first surface of the pressure ring, and the cylindrical part and the punch are placed coaxially. Along the axial direction of the mold, the first surface of the pressure ring has a height dimension h that is lower than the surface of the positioning block away from the punch, and the height dimension h is greater than the flange fillet dimension.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) This forming method changes the deformation mode of the conical surface suspension area from traditional compression deformation to tensile deformation, thus avoiding the possibility of wrinkling from the source.

[0023] 2) The forming mold can ensure symmetry and uniformity when flanging the cylindrical part by accurately positioning the cylindrical part, realizing one-time precise forming of the conical part and effectively avoiding the wrinkling and cracking problems of traditional forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic cross-sectional view of the thin-walled conical member according to Example 1 of the present invention;

[0025] Figure 2 Schematic cross-sectional view of the cylindrical member according to Example 1 of the present invention;

[0026] Figure 3 Schematic diagram of the drawing and flanging process of the thin-walled conical part according to Example 1 of the present invention (the figure shows a flangeless conical part);

[0027] Figure 4 This is a cross-sectional view of the forming mold described in Example 2 of the present invention;

[0028] Figure 5 Schematic diagram of a forming process of a thin-walled conical part in the background art;

[0029] Figure 6 for Figure 5 Schematic diagram of the cone forming process principle for medium-thin-walled conical parts. DETAILED DESCRIPTION

[0030] In order to clearly illustrate the technical features of this solution, the technical solution is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0032] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0035] Example 1

[0036] This embodiment provides a method for forming a thin-walled conical part, specifically: Figure 1 The material of the thin-walled cover with flange and rounded corners is 0Cr18Ni9 (hereinafter referred to as the conical part 1). The forming method is to first draw the blank into a shape such as Figure 2After the cylindrical part 2 with flange edge 21 is formed, the conical surface 11 and flange portion 12 are formed by flanging. Figure 2 The diameter of the middle cylindrical member 2 must be equal to or slightly larger than the base diameter of the conical member 1, specifically 1 to 1.1 times the base diameter. Preferably, the diameter of the cylindrical member 2 is equal to the base diameter of the conical member 1. During the subsequent flanging process, the height of the cylindrical member 2 is designed based on the neutral layer length of the conical member 1. This allows the conical surface's overhang area to deform in a tensile manner, rather than through compression in traditional forming, thus preventing wrinkling from occurring in the first place.

[0037] Figure 3 The figure shows the entire forming process. The principle for determining the height H of the cylindrical part 2 is as follows: define the diameter of the cone mouth of the conical part 1 including the flange fillet as D1, the diameter of the cone bottom as D2, and select a position C with a diameter of D1 on the flange edge 21 of the cylindrical part. Then, the neutral layer length from this position C to the end E of the cylindrical bottom fillet is equal to the neutral layer length from the diameter D1 of the conical part 1 (A) to the end (B) of the cone bottom fillet.

[0038] The number of deep drawing times required to form the cylindrical part 2 is determined according to the diameter of the cone bottom of the conical part 1 and the unfolded size of the cylindrical part 2.

[0039] Figure 1 The relevant dimensions of the conical part of this embodiment are given as an example. The diameter D2 of the cone bottom is φ329.2mm, and the diameter D1 of the cone mouth including the flange fillet is φ390mm. According to the drawing measurement or conventional calculation, H can be obtained as 79.76mm. Figure 2 According to the dimensions shown, conventional calculations show that the unfolded dimension of the cylindrical part is φ502.6 mm, and the drawing coefficient is 329.2 / 502.6≈0.65. Therefore, this embodiment only requires one drawing to form the cylindrical part.

[0040] If the thin-walled conical part to be formed is a flangeless conical part (see Figure 3 ), the same method can still be used to first form a conical part with a flange, then remove the flange. Unlike the previous method, the flange is now an additional forming edge on the conical part, used to transfer force during the subsequent flanging process. The flange radius of the forming edge is generally approximately five times the wall thickness of the conical part.

[0041] It should be noted that the dimensions shown in the drawings of the present invention are only examples and do not constitute a limitation to the technical solutions of the present invention.

[0042] Example 2

[0043] This embodiment describes the flanging forming process in the forming method of embodiment 1: the flanging forming is achieved by using a one-time flanging forming die, such as Figure 4As shown, the mold includes a die 3 and a punch plate 4, and the punch plate 4 is provided with a punch 5, a push rod 6, a pressure ring 7 and a positioning block 8. The push rod 6 passes through the punch plate 4 and is connected to the pressure ring 7. The pressure ring 7 can be controlled to move by the push rod 6. The positioning block 8 is detachably arranged on the top of the punch 5. The positioning block 8 and the punch 5 form a complete inner conical surface of the conical part, wherein the positioning block 8 is controlled by an elastic control part 9 to move away from the punch 5 along the axial direction of the mold, and the positioning block 8 can be gradually reset as the die 3 and the punch 5 are closed. The elastic control part 9 passes through the center of the punch 5 and the punch plate 4 in sequence.

[0044] The elastic control part 9 includes a limiting rod 91 connected to the positioning block 8 and a spring 92 sleeved on the outer periphery of the limiting rod 91, wherein the two ends of the spring 92 respectively abut against the end face of the positioning block 8 and the end face of the convex template 4, and the elastic control effect of the elastic control part 9 is achieved by the elastic force of the spring 92.

[0045] The limiting rod 91 of this embodiment is a limiting bolt. The positioning block 8 is provided with a threaded hole adapted to the limiting bolt. The bolt head of the limiting bolt can be limited by the convex template 4 to prevent the spring 92 from extending to the limit length.

[0046] The working process of the above mold is as follows: when the cylindrical part 2 needs to be placed on the mold for flanging operation, the push rod 6 is first pushed up along the axial direction of the mold to move the blank holder 7 upward, and the flange edge 21 of the cylindrical part is attached to the first surface of the blank holder 7 (i.e. Figure 4 The upper surface of the blank holder in the middle position), at this time, the first surface of the blank holder 7 has a surface lower than the surface of the positioning block 8 away from the punch (i.e. Figure 4 The height dimension h of the upper surface of the positioning block in the orientation must be greater than the flange radius. In this embodiment, h is set to 5-10 mm. The cylindrical member 2 is then positioned over the positioning block 8, ensuring that the cylindrical member 2 and the punch 5 are coaxially positioned. The aforementioned height dimension h is set to facilitate precise centering using the straight portion of the cylindrical member 2, ensuring symmetry and uniformity during flanging of the cylindrical member 2. Finally, the die 3 is controlled to descend, and the cylindrical flange 21 is clamped downward by the die 3 and the blank holder 7, completing the precise flanging of the conical surface of the conical member 1 in one step.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 2 is that the limiting rod is a rod with limiting parts set at both ends, and the positioning block and the convex template respectively have a accommodating area that cooperates with the corresponding limiting parts. The limiting parts are used to prevent the limiting rod and the positioning block and the convex template from detaching.

[0049] The forming method and flanging forming mold of the present invention not only have a good forming effect on thin-walled conical parts, but are especially suitable for thin-walled high-conical parts. They can achieve efficient and stable forming of thin-walled conical parts, significantly improve the forming surface quality, and through the special structural design of the mold, one-time flanging forming is achieved, which greatly improves the forming efficiency and reduces the forming cost.

[0050] Obviously, the above embodiments are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for forming a thin-walled conical part, characterized in that: After the blank is drawn into a cylindrical part with a flange edge, it is flanging-formed into a conical part. The cylindrical diameter of the cylindrical part is 1 to 1.1 times the diameter of the cone bottom of the cone part. During the flanging forming process, the height of the cylindrical part is designed based on the neutral layer length of the cone part, so that the conical surface suspended area of ​​the cone part is formed by stretching deformation; the principle for determining the height H of the cylindrical part is as follows: the diameter of the cone mouth of the cone part including the flange fillet is defined as D1, the cone bottom diameter is D2, and the diameter D1 position is selected on the flange edge of the cylindrical part. The neutral layer length from the position to the end of the cylinder bottom fillet is equal to the neutral layer length from the cone diameter D1 to the end of the cone bottom fillet.

2. The method for forming a thin-walled conical part according to claim 1, characterized in that: The cylinder diameter of the cylindrical part is 1 times the diameter of the cone bottom of the conical part.

3. The method for forming a thin-walled conical part according to claim 1, wherein: The number of deep drawing times is determined according to the cone bottom diameter of the conical part and the unfolded size of the cylindrical part.

4. The method for forming a thin-walled conical part according to claim 1, wherein: The drawing operation adopts hard die drawing.

5. The method for forming a thin-walled conical part according to claim 1, wherein: The drawing operation adopts liquid filling deep drawing.

6. A one-step flanging forming die used in the thin-walled conical part forming method according to any one of claims 1 to 5, characterized in that: It includes a female mold and a male mold plate, and the male mold plate is provided with a punch, a push rod, a pressure ring and a positioning block. The push rod passes through the male mold plate and is connected to the pressure ring. The pressure ring can be controlled to move by the push rod. The positioning block is detachably arranged on the top of the male mold. The positioning block is controlled by an elastic control part to move away from the male mold along the axial direction of the mold and gradually reset as the female mold and the male mold are closed. The elastic control part passes through the male mold.

7. The one-step flanging forming die according to claim 6, characterized in that: The elastic control part includes a limiting rod connected to the positioning block and a spring sleeved on the outer periphery of the limiting rod.

8. The one-step flanging forming die according to claim 7, characterized in that: The limiting rod is a limiting bolt, and the positioning block is provided with a threaded hole adapted to the limiting bolt.

9. The one-step flanging forming die according to claim 6, characterized in that: When the cylindrical part is placed on the mold for flanging operation, the flange edge of the cylindrical part is attached to the first surface of the pressure ring, and the cylindrical part and the punch are placed coaxially. Along the axial direction of the mold, the first surface of the pressure ring has a height dimension h lower than the surface of the positioning block away from the punch, and the height dimension h is greater than the flange fillet dimension.

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