Thin-wall conical part forming method and one-time flanging forming die thereof

Abstract

The invention discloses a thin-wall conical part forming method and a one-time flanging forming die thereof, the forming method comprises the steps that a blank is drawn into a cylindrical part with a flange edge, then the conical part is formed through flanging, the cylinder diameter of the cylindrical part is 1-1.1 times of the diameter of the cone bottom of the conical part, and in the flanging forming process, the diameter of the cylindrical part is 1-1.1 times of the diameter of the cone bottom of the conical part. The height of the cylinder part is designed on the basis of the length of the neutral layer of the conical part, so that the conical surface suspension area of the conical part is subjected to tensile deformation forming. According to the forming method, the deformation mode of the conical surface suspension area is changed into tensile deformation from traditional compression deformation, and the possibility of wrinkling is avoided from the source. According to the forming die, the cylindrical part is accurately positioned to be flanged, it can be guaranteed that the part is symmetrical and uniform during flanging, one-time accurate forming of the conical part is achieved, and the problems of wrinkling and cracking in traditional forming are effectively avoided.

Description

Technical Field

[0001] The 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, processing thin-walled conical parts with a wall thickness of about 0.6mm and a cone angle of about 16°, during the deep drawing process, wrinkles are easily formed due to the existence of the suspended area of ​​the cone surface (the middle wall area except the flange edge and the cone bottom), and the quality is unstable. Regardless of whether a hard die is used for one-time deep drawing 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 Another thin-walled conical part forming process is shown, which is drawn by 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 325 mm into a cylindrical part with an inner diameter of 178 mm; the second process is to draw a cylindrical part with a flange having a diameter equal to the average diameter of the conical part and a height equal to the height of the conical part, see Figure 5 Figure a in Figure 1. In order to ensure that the material has good plasticity, intermediate annealing is performed after each deep 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 flanged cylindrical blank, 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, and the deformation is equivalent to the process of flanging; when the punch reaches the bottom dead center, the conical part is pressed.

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

[0006] The patent with publication number CN101733338A discloses a process for forming ultra-deep conical thin-walled parts, and the process steps are as follows: (1) blanking and punching: the surface of the strip of low-carbon steel material is coated with lubricating oil and then placed in a blanking and punching die with a pressure ring for punching. The tensile coefficient indicating the degree of deep drawing 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 hole diameter 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, i.e., 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) Cutting: Cut the workpiece on the machine tool. The volume of the workpiece after cutting is equal to The finished products have the same volume, and the incision length is converted according to the equal volume. The margin before the incision is 2mm~4mm; (4) Three consecutive taper drawing: After the workpiece surface after the incision is coated with lubricating oil, it is placed in the taper drawing die for the first, second and third taper drawing. The stretching coefficient of the deformed part of the workpiece each time, that is, the small end hole diameter after this taper drawing ÷ the hole diameter before deep drawing, is controlled to be 0.75~0.8. 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 fillet size between the small end of the tapered hole and the cylindrical hole is approximately equal to twice the cylindrical hole diameter of this taper drawing. The bottom fillet R value is half of the difference between the hole diameter before taper drawing and the hole diameter after taper drawing; (5) Oxygen-free annealing: The workpiece after three taper drawing 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 taper drawing, and the process conditions are controlled the same as the first, second and third taper drawing 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 difficult forming of ultra-deep tapered thin-walled parts is solved; the wall of the workpiece is thinned and deep drawn before taper pulling, and the subsequent process utilizes the local thinning of the bottom fillet of the workpiece during taper pulling to gradually reduce the small-end cylindrical hole diameter, so that the wall thickness of the workpiece 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 wrinkling and it is impossible to 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 which can effectively prevent instability and wrinkling during the forming process and can form them quickly, in view of the defects of the prior art.

[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 a thin-walled conical part comprises drawing a blank into a cylindrical part with a flange edge, and then flanging the blank 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 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 hanging area of ​​the conical part is formed by stretching deformation.

[0012] Furthermore, the cylinder 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 tapered 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, 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 conical part diameter D1 to the end of the cone bottom fillet.

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

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

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

[0017] A one-time flanging forming die used in the above-mentioned thin-walled conical part forming method comprises a female die and a male die, the male die is provided with a male die, a push rod, a blank holder and a positioning block, the push rod passes through the male die and is connected to the blank holder, the blank holder 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 die, and is 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 suspended area of ​​the conical surface from traditional compression deformation to tensile deformation, thereby 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, realize one-time precise forming of the conical part, and effectively avoid the wrinkling and cracking problems of traditional forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic cross-sectional view of the thin-walled conical part described in Example 1 of the present invention;

[0025] Figure 2 It is a cross-sectional schematic diagram of the cylindrical member described in Example 1 of the present invention;

[0026] Figure 3 This is a 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 is a cross-sectional view of the molding die described in Example 2 of the present invention;

[0028] Figure 5 It is a schematic diagram of a forming process of a thin-walled conical part in the background technology;

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

[0030] In order to clearly illustrate the technical features of the present solution, the present 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", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying 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 only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0034] In the present application, unless otherwise clearly 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 (hereinafter referred to as the conical part 1) is 0Cr18Ni9. 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 cylinder diameter of the middle cylinder 2 needs to be equal to or slightly larger than the bottom diameter of the conical part 1, specifically 1 to 1.1 times the diameter of the conical bottom of the conical part. It is preferred that the cylinder diameter of the cylinder 2 is equal to the diameter of the conical bottom of the conical part 1. In the subsequent flanging forming process, the height of the cylinder 2 is designed based on the neutral layer length of the conical part 1, so that the conical surface hanging area can be changed from the compression deformation in the traditional forming to the tensile deformation, thereby avoiding the possibility of wrinkling from the source.

[0037] Figure 3 The figure is a schematic diagram of the entire forming process. The principle for determining the height H of the cylindrical part 2 is: 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 the position C of diameter D1 on the flange edge 21 of the cylindrical part. The neutral layer length from the 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 for forming the cylindrical part 2 is determined according to the cone bottom diameter of the conical part 1 and the unfolded size of the cylindrical part 2.

[0039] Figure 1 The relevant dimension examples of the conical part of this embodiment are given. The diameter D2 of the cone bottom is φ329.2 mm, and the diameter D1 of the cone mouth including the flange fillet is φ390 mm. According to the drawing measurement or conventional calculation, H can be obtained to be 79.76 mm. Figure 2 According to the dimensions shown, the unfolded dimension of the cylindrical part can be obtained by conventional calculation as φ502.6 mm, and the drawing coefficient is 329.2 / 502.6≈0.65. Therefore, the cylindrical part can be formed by only one drawing in this embodiment.

[0040] If the thin-walled conical part to be formed is a flangeless conical part (see Figure 3 ), the above method can still be used to first form a conical part with a flange edge, and then remove the flange part. The difference from the above is that the flange edge at this time is the forming process edge added to the conical part, which is used for the pressure edge force transmission during the subsequent flanging forming. Generally, the flange radius size of the forming process edge is about 5 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 on 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 mold, such as Figure 4As shown, the mold includes a die 3 and a punch plate 4, on which a punch 5, a push rod 6, a blank holder 7 and a positioning block 8 are provided. The push rod 6 passes through the punch plate 4 and is connected to the blank holder 7. The blank holder 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 cone 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 limit rod 91 connected to the positioning block 8 and a spring 92 sleeved on the outer periphery of the limit rod 91, wherein the two ends of the spring 92 are respectively in contact with the end faces of the positioning block 8 and the convex template 4, and the elastic control effect of the elastic control part 9 is achieved through 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-mentioned 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 In this case, the first surface of the blank holder 7 has a surface lower than the surface of the positioning block 8 facing away from the punch (i.e. Figure 4 The height dimension h of the upper surface of the positioning block in the orientation should be greater than the flange fillet dimension. In this embodiment, h is 5-10 mm. Then ensure that the cylindrical part 2 is sleeved on the positioning block 8 so that the cylindrical part 2 and the punch 5 are coaxially placed. The purpose of setting the height dimension h is to facilitate accurate centering with the straight part of the cylindrical part 2 to ensure symmetry and uniformity when the cylindrical part 2 is flanging. Finally, control the downward movement of the die 3, and clamp the cylindrical flange 21 downward through the die 3 and the blank holder 7 to complete the accurate flanging of the conical surface of the conical part 1.

[0047] Example 3

[0048] The difference between this embodiment and embodiment 2 is that the limiting rod is a rod with limiting parts respectively arranged at both ends, and the positioning block and the convex plate respectively have a accommodating area that cooperates with the corresponding limiting parts, and the limiting parts are used to prevent the limiting rod and the positioning block and the convex plate 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 particularly suitable for thin-walled high-conical parts. They can achieve efficient and stable forming of thin-walled conical parts and significantly improve the forming surface quality. 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 clearly illustrating the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope 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 cylinder 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 hanging area of ​​the conical part is formed by stretching deformation.

2. The method for forming a thin-walled conical part according to claim 1, characterized in that: The cylinder diameter of the cylinder 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 or 2, characterized in that: The principle for determining the height H of the cylindrical part is as follows: define the diameter of the conical part's taper mouth including the flange fillet as D1, the cone bottom diameter as D2, select a diameter D1 position on the cylindrical part's flange edge, and then the neutral layer length from the position to the end of the cylindrical part's bottom fillet is equal to the neutral layer length from the conical part's diameter D1 to the end of the cone bottom fillet.

4. The method for forming a thin-walled conical part according to claim 3, characterized in that: 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.

5. The method for forming a thin-walled conical part according to claim 1, characterized in that: The drawing operation adopts hard die drawing.

6. The method for forming a thin-walled conical part according to claim 1, characterized in that: The drawing operation adopts liquid filling deep drawing forming.

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

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

9. The one-step flanging forming die according to claim 8, 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.

10. The one-step flanging forming die according to claim 7, 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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