Method for forming a conical thin-walled cylindrical part with recessed band

Abstract

The application discloses a forming method of a thin-walled cylindrical part with a concave cover and a taper, wherein the thin-walled cylindrical part is formed by a plate material, the plate material is first stretched to have a structure with a cylinder and a flange, and then the cylinder is expanded and formed into a taper cylinder and a concave cover in a mold by using a liquid filling mode; a concave part matched with the concave cover is arranged on a convex die of the mold; and the cylinder height and the diameter of the cylinder are required to be: when the cylinder is put into the mold, the bottom corner of the cylinder is in contact with the concave die taper surface of the mold, and the flange is just attached to the outer edge plane of the concave die. The forming method expands and forms the taper surface and the concave cover of the cylinder by using the liquid filling mode, liquid is filled in the concave die, which can force the part to gradually attach to the punch, and the suspended area is small; meanwhile, by limiting the cylinder height and the cylinder diameter of the stretched and formed cylinder, the phenomenon that the part is wrinkled on the side wall and the concave cover corner is thinned and cracked can be effectively prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of die forming, in particular to a forming method of a thin-walled cylindrical part with concave and convex parts and a taper. BACKGROUND

[0002] Many parts on an aero-engine are thin-walled parts, for example, a part as shown in the accompanying drawings of the specification, which is on a certain type of engine. Figure 1 The material of the part is 0Cr18Ni9, and the wall thickness is only 0.6mm. There is at least one taper on the side wall of the part, and some have concave and convex parts on the side wall. Since such parts are tapered parts with thin walls, the side wall is not in contact with the punch and die during forming, and the part blank cannot be in contact with the punch to produce beneficial friction, which leads to thinning and cracking of the part, especially the corner thinning and cracking at the bottom of the concave and convex part. The size requirement of the concave and convex part is high, and it is easy to rebound out of tolerance through ordinary stretching. In addition, the side wall of the part is also prone to tangential compression and wrinkle instability during forming.

[0003] Patent application No. CN113070400A discloses a thin-walled tapered part stamping forming die, which comprises a die assembly, a blank holder assembly, and a punch assembly. The die assembly and the blank holder assembly are oppositely arranged, and the die assembly and the blank holder assembly are respectively connected with the first driving part and the second driving part of the stamping equipment. The end face of the die assembly facing the blank holder assembly is concave, forming a forming cavity for forming a tapered part. The blank holder assembly is provided with an installation cavity which is oppositely arranged and communicated with the forming cavity. The punch assembly is installed in the installation cavity and fixed with the installation platform of the stamping equipment. The punch assembly is used to support the blank plate to be formed, so that the die assembly and the blank holder assembly can clamp the blank plate. The punch assembly is also used to deform and extrude into the forming cavity during the movement of the die assembly and the blank holder assembly clamping the blank plate, so as to press the blank plate tightly between the inner wall surface of the forming cavity and the outer wall surface of the punch assembly, so as to form the tapered part and prevent the wall surface of the tapered part from wrinkling.

[0004] The above-mentioned patent technical solution is to deform and extrude the elastic punch to make the blank plate tightly adhere to the inner wall surface of the forming cavity and the outer wall surface of the punch assembly, so as to reduce the possibility of instability and wrinkling of the part. However, in actual work process, the elastic punch often cannot achieve equal elasticity everywhere to uniformly extrude the part, so it is an ideal state to avoid instability and wrinkling of the part. Moreover, the part in the above-mentioned patent solution does not have a concave and convex part. If the part has a concave and convex part, the forming cavity needs to be provided with a corresponding concave part in addition to the convex part on the elastic punch. At this time, the convex part and the concave part need to consider the angular problem, which increases the design complexity of the die. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide a forming method for a thin-walled cylindrical part with a concave bag and a taper, which has no wrinkles on the side wall and no cracking at the corner.

[0006] The object of the present application is achieved by the following technical solutions:

[0007] The forming method for a thin-walled cylindrical part with a concave bag and a taper, the thin-walled cylindrical part is formed by a plate material, the plate material is first stretched to have a structure of a cylinder and a flange, and then the cylinder is expanded into a taper cylinder and a concave bag in a mold by a liquid filling method, a concave part matched with the concave bag is arranged on a convex mold of the mold; the cylinder height and the diameter of the cylinder are required to be: when the cylinder is put into the mold, the bottom corner of the cylinder is in contact with the taper surface of the concave mold, and the flange is just matched with the outer edge plane of the concave mold.

[0008] Further, the determination principle of the cylinder height and the diameter of the cylinder is: the surface area of the taper cylinder is greater than the surface area of the cylinder, and after the surface area of the cylinder is converted into the surface area of the taper cylinder, the cylindrical part still has a stretching amount.

[0009] Further, the stretching amount is greater than 4 mm.

[0010] Further, the liquid filling method is: the convex mold of the mold is lowered to contact the cylinder, and then liquid is filled into the liquid chamber of the mold.

[0011] Further, the liquid filling pressure gradually increases as the convex mold gradually descends.

[0012] Further, the increasing trend of the liquid filling pressure stops after the convex mold and the cylinder are completely matched.

[0013] Further, after the liquid filling pressure stops increasing, the convex mold continues to descend, so that a gap of 1.1 times the material thickness is maintained between the convex mold and the concave mold.

[0014] Further, the plate material is cut by laser.

[0015] Further, the laser cutting spatter and burr on the plate material need to be removed.

[0016] Further, the plate material is sprayed with protective paint.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The present forming method stretches the cylinder by a steel mold, and then expands the cylinder by a liquid filling method to form a taper surface and a concave bag on the taper surface, the liquid filled in the concave mold can force the part to gradually match the punch, and the suspended area is small; at the same time, by limiting the cylinder height and the cylinder diameter of the stretched cylinder, the phenomenon of wrinkles on the side wall and thinning and cracking at the corner of the concave bag can be effectively prevented.

[0019] After final forming, the part is corrected with 1.1 times the material thickness between the punch and the die, which solves the problem of leaving traces of the previous forming process due to insufficient pressure, and the dimension precision of the formed part is high, and the part forming quality is high. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Structure sectional view of the thin-walled cylindrical part with concave band and cone in Example 1;

[0021] Figure 2 Schematic diagram of the structure of the cylinder after drawing of the sheet metal in Example 1;

[0022] Figure 3 Schematic diagram of the die structure for drawing the cylinder of the sheet metal in Example 1;

[0023] Figure 4 Schematic diagram of the die structure for forming the cone cylinder and the concave band in Example 1;

[0024] Figure 5 Schematic diagram of the swing of the cylinder in Example 1 in the die; Figure 4

[0025] Figure 6 Schematic diagram of the size for calculating the cylinder height in Example 1. DETAILED DESCRIPTION

[0026] In order to clearly illustrate the technical features of the scheme, the technical scheme will be described in detail below with specific embodiments and in conjunction with the accompanying drawings.

[0027] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be practiced in other ways different from those described herein, and therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0028] ​Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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, an electrical connection, or a communication 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 application according to the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0031] Example 1

[0032] like Figure 1 The thin-walled cylindrical component shown is a part used in aero engines. Its wall thickness is 0.6 mm, and the component's sidewall has two conical surfaces at different angles (e.g., ...). Figure 1The figure shows 15°, 33' and 23°), and the sidewall has two recesses 1; this embodiment provides a forming method for such a conical thin-walled cylindrical part with recesses: the thin-walled cylindrical part is formed from sheet metal, firstly the sheet metal is formed using... Figure 3 The steel mold shown is used to stretch out a shape with a cylinder 2 and a flange 3, as shown. Figure 2 The structure shown is then used to form the cylindrical portion in a manner similar to... Figure 4 The mold shown uses a liquid-filling method to expand and form the cone 4 and the concave 1. Figure 4 In the mold, only the punch 62 needs to have a recess that matches the concave 1; during the process of filling and expanding the cylinder 2 to form the cone 4, the amount of tapered stretching needs to be minimized. Therefore, the cylinder needs to have a certain stretching height during forming, and the cylinder diameter also needs to be considered. Generally, the cylinder diameter is determined by designing it first. Figure 3 The diameter of the punch in the steel die.

[0033] Specifically, the cylindrical part is in Figure 4 See the arrangement of elements in the mold. Figure 5 The requirements for the height and diameter of cylinder 2 are as follows: cylinder 2 is placed... Figure 4 When inside the mold, the bottom corner of the cylinder 2 contacts the conical surface of the die 61, while the flange 3 fits precisely against the outer edge plane of the die 61, so that the part is placed in the center of the steel mold. The diameter of the cylinder 2 is selected at approximately the lower middle position of the part.

[0034] The principle for more accurately determining the height and diameter of cylinder 2 is: to ensure that the surface area of ​​the conical cylinder is greater than that of the cylindrical cylinder, and that after the surface area of ​​the cylindrical cylinder is converted into the surface area of ​​the conical cylinder, the cylindrical component still has a stretch, i.e., the distance between the cylindrical component and the conical cylinder. Figure 4 There is still stretching at the bottom of the middle die cavity.

[0035] To avoid the risk of wrinkling during cylinder expansion, the stretching depth of cylinder 2 should be as deep as possible, but the cylinder depth should still be less than the depth of the final formed cone. First, calculate the surface area S of the final part's sidewalls and bottom. 锥 Surface area, then calculate the effective surface area of ​​the cylinder, i.e., S. 圆筒 Effective surface area. See the dimensioning for cylinders and conical cylinders. Figure 6 h2 锥 Surface area = πL²[(d₁ + d₃) ÷ 2] + π(d₃ ÷ 2)², S 圆筒 Effective surface area = πd²h² + π(d²÷2)² + πL¹², where S is the effective surface area to ensure deformation during the forming of the cone. 锥 >S 圆筒 Furthermore, considering that the part still experiences stretching even after the surface area of ​​the cylinder is completely converted into the surface area of ​​the cone, the final cylinder height is determined by combining these factors. h2 ​and diameter d2; after the diameter d2 is determined, the effective surface area of the cylinder is controlled by the height.

[0036] To ensure the quality of the part forming, preferably, the distance between the cylindrical part and the bottom of the die cavity should be at least 4mm, i.e. (S 锥 -S 圆筒 πd2>4, so as to further accurately determine the height of the cylinder h2 and the range of diameter d2.

[0037] The forming die and process of the cylinder and the conical cylinder are described as follows:

[0038] Forming cylinder 2: Figure 3 In the process, the steel die is fixed on the machine tool, the cushion block 52 is in direct contact with the press ejector cylinder on the machine tool, then the cushion block 52 is fixed with the top plate 53 through bolts, the top rod 54 is fixed with the top plate 53 through bolts, and the top rod 54 is connected with the steel die pressure ring 55 through the threads of the top rod 54 itself. Adjust the appropriate machine tool processing parameters, the steel die cavity 56 opens along with the machine tool, then the press ejector cylinder goes up, the cushion block 52 in contact with the press ejector cylinder is lifted up, when the cushion block 52 goes up along with the press ejector cylinder, the top plate 53 connected with the cushion block 52 through bolts also goes up, finally the steel die pressure ring 55 stops at about 1mm above the punch 51 under the action of the press ejector cylinder, the sheet metal can be positioned by the four positioning pins 57 on the steel die pressure ring 55, the steel die cavity 56 presses the outer edge of the sheet metal on the steel die pressure ring 55 along with the machine tool, the sheet metal is stretched into a structure with a cylinder and a flange along with the machine tool continues to go down, finally the top surface of the plate 58 is attached to the bottom surface of the upper die plate 59, the sheet metal completes the cylinder stretching, then along with the machine tool goes up, the steel die cavity 56 goes up, the steel die is opened, the press ejector cylinder ejects the part, and the cylinder forming is completed.

[0039] The forming cone cylinder 4: the mold is fixed on the machine tool, the pressure ring 63 and the punch 62 move with the machine tool, the mold is opened, the cylinder is placed in the liquid chamber 64, the bottom corner of the cylinder 2 is in contact with the tapered surface of the liquid chamber 64 and the concave die 62, and at this time, the lower surface of the flange 3 is in contact with the upper surface of the liquid chamber 64. Then the pressure ring 63 moves downward with the outer slide block of the machine tool until it presses the flange 3, and then the punch 62 fixed on the slide block of the machine tool moves downward, and when the punch 62 contacts the cylinder 2, the liquid in the liquid chamber 64 starts to be filled. It should be noted that at this time, there are many suspended areas of the part, and the pressure of the liquid chamber needs to be set smaller, otherwise the suspended areas of the part may be lifted and wrinkled; as the punch 62 moves downward, the part gradually fits the punch 62 under the pressure of the liquid chamber, and the suspended area decreases, so the filling pressure can gradually increase until the cylinder 2 is completely fitted with the punch 62 under the condition that the liquid is continuously increased. The increasing trend of the filling pressure stops until the punch 62 and the cylinder 2 are completely fitted, and then the punch 62 continues to move downward, and the punch 62 moves downward under the limiting action of the bottom plate 65, and the distance of the punch 62 moving downward is ended. At this time, the concave die 61 keeps a gap of 1.1 times the material thickness with the punch 62 and the bottom plate 65, and the final entire profile of the part is further corrected under the interaction of the concave die 61, the punch 62 and the bottom plate 65, which can solve the problem of leaving traces of the first forming process due to insufficient filling pressure and ensure the quality of the profile.

[0040] The plate material for forming the cylindrical part is preferably laser cut, and the laser cutting spatter and burr are removed after cutting to prevent the plate material from being scratched during stretching.

[0041] The present application adopts steel mold combined with liquid filling, first stretches and forms the cylinder by using the steel mold, designs and calculates the relevant dimensions of the cylinder, and then expands and forms the cone and the concave bag of the cylinder by using the liquid filling method. After final forming, the punch and the concave die keep 1.1 times the material thickness to correct the part, eliminate the processing traces of the previous process, solve the problems of wrinkling of the side wall and cracking of the bottom concave bag of the thin-walled cylindrical part with a concave bag and a cone, and the size precision of the formed part is high and the forming quality is excellent.

[0042] The liquid filling forming method adopted by the present application is especially suitable for the forming of the thin-walled cylindrical part with multiple tapers on the side wall, does not need to make complex molds, greatly reduces the part forming cost, and avoids setting the corresponding structure of the concave die for forming the concave bag, and naturally does not need to consider the angular problem of the punch and the concave die, because the liquid chamber pressure can ensure that the part is close to the punch and then formed.

[0043] Example 2

[0044] The difference between this embodiment and example 1 is that the plate material is laser cut, and the laser cutting spatter and burr are removed after cutting to prevent the plate material from being scratched during stretching, and then the plate material is sprayed with protective paint.

[0045] Example 3

[0046] The difference between this embodiment and embodiment 1 is that, in order to ensure the quality of the part forming, the distance between the cylindrical part and the bottom of the die cavity should have a stretching amount of at least 5mm, i.e. (S 锥 -S 圆筒 ) ÷ πd2> 5, so as to further accurately obtain the range value of the height of the cylinder and the diameter d2. h2

[0047] Embodiment 4

[0048] The difference between this embodiment and embodiment 1 is that, in order to ensure the quality of the part forming, the distance between the cylindrical part and the bottom of the die cavity should have a stretching amount of at least 6mm, i.e. (S 锥 -S 圆筒 ) ÷ πd2> 6, so as to further accurately obtain the range value of the height of the cylinder and the diameter d2. h2

[0049] Obviously, the above embodiments are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the implementation manners of the present application. Based on the above description, those skilled in the art can make other different forms of changes or modifications. Here, it is not necessary and also impossible to exhaust all the implementation manners. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the claims of the present application.​​

Claims

1. A method for forming a thin-walled cylindrical part with a concave and conical shape, wherein the thin-walled cylindrical part is formed from sheet metal, characterized in that, First, the sheet metal is stretched into a structure with a cylinder and a flange. Then, the cylinder is expanded in a mold by filling with liquid to form a cone and a concave. The punch of the mold is provided with a concave part that matches the concave. The cylinder height and diameter are required to be such that when the cylinder is placed in the mold, the bottom corner of the cylinder contacts the conical surface of the concave mold, and the flange fits exactly against the outer edge plane of the concave mold.

2. The method for forming a thin-walled cylindrical part with a concave bulge and a conical shape according to claim 1, characterized in that, The principle for determining the height and diameter of the cylinder is that the surface area of ​​the cone is greater than the surface area of ​​the cylinder, and the cylindrical component still has a stretch after the surface area of ​​the cylinder is converted into the surface area of ​​the cone.

3. The method for forming a thin-walled cylindrical part with a concave bulge and a conical shape according to claim 2, characterized in that, The stretching amount is greater than 4 mm.

4. The method for forming a thin-walled cylindrical part with a concave bulge and a conical shape according to claim 1, characterized in that, The filling method is as follows: when the punch of the mold descends to the contact cylinder, it begins to fill the liquid chamber of the mold with liquid.

5. The method for forming a thin-walled cylindrical part with a concave bulge and a tapered shape according to claim 4, characterized in that, As the punch gradually descends, the filling pressure gradually increases.

6. The method for forming a thin-walled cylindrical part with a concave bulge and a tapered shape according to claim 5, characterized in that, The increasing trend of the hydraulic pressure continues until the punch and the cylinder are fully fitted together.

7. The method for forming a thin-walled cylindrical part with a concave bulge and a tapered shape according to claim 6, characterized in that, After the filling pressure stops increasing, the punch continues to descend, maintaining a gap of 1.1 times the material thickness between the punch and the die.

8. The method for forming a thin-walled cylindrical part with a concave bulge and a tapered shape according to claim 1, characterized in that, The sheet material is laser-cut.

9. The method for forming a thin-walled cylindrical part with a concave bulge and a conical shape according to claim 8, characterized in that, Laser cutting spatter and burrs on the sheet material must be removed.

10. The method for forming a thin-walled cylindrical part with a concave bulge and a tapered shape according to claim 1, characterized in that, The sheet material is sprayed with protective paint.

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