Edge bending machining method for large-diameter thin-wall cylinder part

Abstract

The invention discloses a flange machining method for a large-diameter thin-wall cylinder part. The flange machining method comprises the steps of material preparation, blanking, edge rolling or roll bending, welding, overall expansion, flange and mold correction which are sequentially carried out. According to the method, overall expansion is adopted for the J-shaped outer flanging structure and the barrel, the conical end face type surface structure is obtained to serve as the middle structure of the J-shaped structure, and then the final J-shaped outer flanging is obtained by independently conducting edge bending treatment and mold tire correction treatment on the conical structure. According to the method, the problem of welding deformation caused by a traditional welding method is solved, the problem that follow-up assembly is affected due to the fact that the J-shaped outer flanging contour is not accurate enough is avoided, the tool cost is further saved, and the molded surface forming quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a reverse bending processing method for a large thin-walled cylinder part. Background Art

[0002] The sheet metal parts on aircraft engines have various shapes, ranging from small bracket parts to large cylinder parts. The structure and shape of the parts are also different. In order to meet the assembly and performance requirements of the final product, the integrity of the part structure plays a key role.

[0003] like Figure 3 and Figure 4 The figure shows an "inner ring" part, that is, a large-diameter thin-walled sheet metal part with a J-shaped structure of length L1. The axial section of the part is a corrugated cylinder. In order to ensure the matching of the parts in the later assembly and improve the overall assembly quality of the components, the integral forming processing of the "inner ring" part is very important. The outer diameter corresponding to the J-shaped structure is ΦD, the outer diameter at the negative angle structure is Φd, and the outer diameter of the corrugated cylinder is ΦD1.

[0004] For this part, the traditional processing method is to use a segmented molding structure. Figure 4 The part is split at L2 in the middle, split into two parts, and then formed separately, and finally welded into one part by argon arc welding. However, this forming method is prone to uncontrollable welding deformation in the area near the weld, which is difficult to correct later, resulting in poor contour accuracy of the part, especially the contour of the J-shaped structure, which directly affects the assembly accuracy of the subsequent outer ring connection. Summary of the invention

[0005] In response to the problems recorded in the background technology, the present invention aims to provide a method for bending large-diameter thin-walled cylindrical parts to solve the overall forming problem of similar parts, reduce the tooling and costs generated by multi-stage forming of parts, reduce the welding deformation of J-shaped external flanges in parts, and improve the surface processing quality of parts.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for flanging a large-diameter thin-walled cylindrical part, wherein the large-diameter thin-walled cylindrical part is a cylinder with a wavy circumferential surface, one end of the axial section of the cylinder has a J-shaped outer flange, and a negative angle is formed at the connection between the outer flange and the cylinder generatrix. The method comprises the following steps:

[0008] Step 1, material preparation: select a plate with the same thickness as the large-diameter thin-walled cylinder part, and take the cylindrical surface coaxial with itself in the part drawing of the large-diameter thin-walled cylinder part as the basis, take the generatrix length of the cylindrical surface plus the flattened length of the J-shaped outer flange and a margin as the width of the plate, and take the circumferential development length of the cylindrical surface plus a margin as the length of the plate;

[0009] Step 2, cutting: cutting the plate according to the thickness, width and length determined in step 1, and then dividing the plate into at least two equal pieces along the length direction of the plate;

[0010] Step 3, rolling or bending: rolling or bending the multiple plates in step 2 according to the same curvature;

[0011] Step 4, welding: splicing the multiple plates that have been rolled or bent in step 3 into a cylindrical or conical cylinder, and welding the spliced ​​parts;

[0012] Step 5, overall bulging: placing a cylindrical body or a conical cylindrical body into a bulging mold, and using the bulging mold to perform overall bulging forming on the cylindrical body, the obtained profile includes a circumferential wavy profile, a conical end profile, a cylindrical profile connecting the circumferential wavy profile and the conical end profile, and a negative angle feature between the cylindrical profile and the circumferential wavy profile, wherein the taper angle of the conical end profile is A;

[0013] Step 6, bending: using a roller mold to bend the tapered end surface in step 5 to obtain a partial arc segment connected to the cylindrical surface in the J-shaped outer flange, the roller mold includes an upper roller and a lower roller whose rotating axes are parallel, the axial end surface of the lower roller has a chamfer for forming the partial arc segment of the J-shaped outer flange, the gap between the upper roller and the lower roller is used to accommodate the tapered end surface, the rotating axes of the upper roller and the lower roller are along the radial direction of the cylinder or the tapered cylinder, and the upper roller and the lower roller move around the circumference of the cylinder or the tapered cylinder to implement the bending;

[0014] Step seven, correction: Use a mold that is consistent with the J-shaped outer flange profile and has a negative angle feature to correct the J-shaped outer flange to obtain the accurate shape of the J-shaped outer flange.

[0015] Furthermore, in the step 1, the distances from the generatrix of the cylindrical surface to the crests and troughs in the wavy profile on the circumferential surface of the large-diameter thin-walled cylindrical part are equal.

[0016] Furthermore, in step 2, the plate is equally divided into three pieces along the length direction of the plate.

[0017] Further, in step five, the bulging mold includes a male mold for the inner surface and a female mold for the outer surface, and both the male mold and the female mold are composed of multiple identical bulging petals, wherein the male mold is slidably connected to multiple inclined tracks distributed on a first circumference, and the female mold is slidably connected to multiple inclined tracks distributed on a second circumference, and the first circumference is concentric and coplanar with the second circumference and is located inside the second circumference.

[0018] Furthermore, in step five, the value of the taper angle A is 135°.

[0019] Furthermore, the step between step five and step six also includes a trimming process, in which the large end of the tapered end surface is cut to obtain the accurate length of the J-shaped outer flange.

[0020] Compared with the traditional processing method, the advantages of the present invention include the following aspects:

[0021] 1. It saves the cost of tooling and rough materials and simplifies the mold structure. In step six of the present invention, a bending process is adopted, and the bending is performed by extending and bending the sheet material through a roller mold, which is not a conventional flanging mold or bulging mold. The roller mold is small in size, low in cost, short in processing time, relatively small in deformation, and not prone to cracking problems. Compared with bulging molds or flanging molds that are larger than large-diameter thin-walled cylindrical parts, the cost of roller molds is almost negligible. The tapered end face profile on the rough material saves the rough material cost compared to the traditional bulging or flanging, which is likely to cause cracking at the bend and make the parts scrapped.

[0022] 2. The parts processed by the present invention are integrally formed structures, which avoid the segmented welding of the J-shaped outer flange and the wavy cylinder in the parts, thereby avoiding welding deformation of the parts and improving the strength and surface quality of the parts.

[0023] 3. The present invention ensures the matching of parts in the later assembly and improves the overall performance of the assembly. Since the J-shaped outer flange and the wavy cylinder are integrally expanded, and the J-shaped outer flange is accurately sized through roller bending and mold correction, it is beneficial to the subsequent assembly process.

[0024] 4. The present invention shortens the processing cycle. The traditional processing method is mainly based on the processes of piece forming (J-shaped outer flange and wavy cylinder are formed independently), welding after forming and correction after welding. The processing method of the present invention adopts direct expansion after welding. Compared with the traditional processing method, the welding is flat plate welding (there is a wave structure at the traditional welding point), and one less forming (the traditional J-shaped outer flange and wavy cylinder are formed independently, while the integral forming of the present invention has one more forming), and the processing cycle is greatly shortened.

[0025] At present, the processing method and the mold of the present invention have been used on site, and the purpose and requirements of the present invention have been achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of splicing a plurality of plates into a cylindrical body in the processing method of the present invention;

[0027] Figure 2 It is a schematic diagram of the cylinder after overall expansion in the present invention;

[0028] Figure 3 It is a schematic diagram of a large diameter thin-walled cylinder part;

[0029] Figure 4 yes Figure 3 A magnified schematic diagram of the local area F in the middle;

[0030] Figure 5 It is a schematic diagram of the calculation of the plate size in the material preparation step in the processing method of the present invention;

[0031] Figure 6 It is a schematic diagram of a curved edge roller;

[0032] Figure 7 It is a schematic diagram of the bending process;

[0033] Figure 8 This is a schematic diagram of a curved edge tire. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0035] The core principle of the processing method for the "inner ring" part of the present invention is: using a bulging die to form the wavy structure of the part body and the preformed structure before the J-shaped structure is bent, and then the preformed structure is formed into a J-shaped outer bend in one step through roller bending and mold correction. In short, the realization of this core principle includes the following steps:

[0036] (1) Process the required plate with the same thickness as the final large-diameter thin-walled cylindrical part (for example, 0.6 mm) into a cylindrical or conical structure, such as Figure 1 It is a cylindrical structure with a diameter of Φ and a height of h.

[0037] (2) Place the cylindrical raw material into a bulging die that expands inside and contracts outside to form the main body surface, forming the intermediate structure of the part, such as Figure 2 The intermediate structure includes three features: the first is the circumferential wavy profile, the second is the tapered end face profile (taper angle is A), and the third is the negative angle.

[0038] (3) Figure 2 The conical end surface is used as the bending part to perform roller bending and tire correction to form a J-shaped outer flange. Figure 3 .

[0039] The large-diameter thin-walled cylinder parts processing method of the present invention mainly comprises the following steps:

[0040] Step 1, material preparation: Select a plate with the same thickness as the large-diameter thin-walled cylinder part, based on the cylindrical surface coaxial with itself in the part drawing of the large-diameter thin-walled cylinder part, such as Figure 5 As shown, a cylindrical surface whose generatrix is ​​between the peak and the trough of the wavy profile on the circumferential surface of the cylindrical surface is selected, and the generatrix length of the cylindrical surface plus the length of the J-shaped outer flange structure after flattening (straightening) plus a margin is taken as the width of the plate, and the circumferential development length of the cylindrical surface plus a margin is taken as the length of the plate;

[0041] Step 2: Processing of the raw material: Cut the raw material according to the thickness, width and length of step 1 to obtain a plate, and then divide the plate into 3 equal pieces along the length direction, and weld each plate after rolling it into a circle to form a plate. Figure 1 The cylindrical rough material (width is h, diameter is Φ) is formed by rolling and welding three rectangular plates;

[0042] Step 3: Use Figure 2 The bulging female mold and the male mold with the same inner and outer surfaces will Figure 1 The cylindrical wool is formed into Figure 2 The bulging die bulges the inner and outer surfaces of the cylindrical rough material through multiple radially movable bulging petals (the bulging petals corresponding to the male mold extrude from the inside to the outside along the radial direction, and the bulging petals corresponding to the female mold extrude from the outside to the inside along the radial direction, and the male mold and the female mold are combined to form). Figure 3 and Figure 4 As shown, the outer surface of the part not only finally reverses the bend, but also has a negative angle near the bend (that is, the surface shrinks inward, which can also be understood as the inner diameter becomes smaller inward). Due to the existence of the negative angle, the female mold of the outer surface cannot adopt an integral structure when the part is reversely bent. The present invention makes the female mold of the outer surface into a petal structure (for example, the female mold is made into 3 petals or more petals, and an outer hoop is used to limit the position, refer to Chinese invention patent CN117260278A, 2023.12.22, aircraft engine lobe mixer processing method and external expansion petal design in bulging mold), cooperates with the male mold, so that the cylinder is placed in the mold before bulging, and the part is taken out after bulging, thereby solving the problem that the part cannot be taken out due to the existence of negative angles. Figure 2The taper angle A in the figure is the difficulty in designing the bulging die and determining the rough material. The calculation and value of this angle are related to whether the part can be formed into the final part and whether the rough material is available. If the taper angle A is too large, it will be difficult or impossible to form the final bending edge of the part; if the taper angle A is too small, the rough material cannot be put into the bulging die, and the semi-finished part will eventually have poor molding quality due to the excess material. When selecting the value, the rough material and the forming distance should be considered comprehensively, and the taper angle A should be selected. Figure 4 The middle tangent position (the arc of the J-shaped outer flange) and 135° are formed after forming. Figure 2 The uppermost conical end face profile;

[0043] Step 4: Figure 6 , which is a roller die used for bending, and the die consists of an upper roller, a lower roller (H in the figure is the axial length of the shaft of the upper roller and the lower roller) and a baffle (the baffle is at Figure 6 The left end face of the lower roller in the figure has a chamfer R, which is used to bend the conical end face profile to form a partial arc. When bending the edge, the conical end face profile is inserted into the gap between the upper roller and the lower roller, and the conical end face profile is kept Figure 6 The middle H direction (rotation axis direction) is along the radial direction of the cylinder, so that the upper roller and the lower roller go around the conical end surface together. The conical end surface is deformed and bent under the extrusion of the upper roller, the lower roller and the chamfer R, thereby Figure 7 The OM segment bending forming in the middle left figure is Figure 7 The shape shown in the middle figure (i.e. the arc forming the OL segment);

[0044] Step 5, finally pass Figure 8 The mold shown in the figure corrects the final fit of the flange of the part, that is, the molded Figure 7 The shape of the LM segment in the middle right picture finally completes the J-shaped outer flange. The mold surface includes the cylindrical surface of the cylinder, the J-shaped outer flange surface and the negative angle feature (the thick black line represents the J-shaped outer flange, the thin line is the mold outline, and the J-shaped outer flange covers a part of the mold outline). The J-shaped outer flange plays the role of connecting the outer ring during assembly. The quality of its molding and whether the part is deformed are related to the matching of the part with the outer ring during assembly.

[0045] In the present invention, Figure 7 As shown, after bulging, the tapered end surface can be trimmed to obtain the accurate size of the J-shaped outer flange (i.e. Figure 7 The length is OM in the middle right figure), so the J-shaped outer flange does not need to be trimmed after bending and shaping, ensuring the accuracy of subsequent assembly.

[0046] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. Although the illustrative specific embodiments of the present invention are described above to facilitate the understanding of the present invention by the technical personnel in the field, it should be clear that the present invention is not limited to the scope of the specific embodiments. For ordinary technicians in the field of this technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A method for flanging a large-diameter thin-walled cylindrical part, wherein the large-diameter thin-walled cylindrical part is a cylinder with a wavy circumferential surface, one end of the axial section of the cylinder has a J-shaped outer flange, and the connection between the outer flange and the cylinder generatrix has a negative angle, characterized in that: The processing method comprises the following steps: Step 1, material preparation: select a plate with the same thickness as the large-diameter thin-walled cylinder part, and take the cylindrical surface coaxial with itself in the part drawing of the large-diameter thin-walled cylinder part as the basis, take the generatrix length of the cylindrical surface plus the flattened length of the J-shaped outer flange and a margin as the width of the plate, and take the circumferential development length of the cylindrical surface plus a margin as the length of the plate; Step 2, cutting: cutting the plate according to the thickness, width and length determined in step 1, and then dividing the plate into at least two equal pieces along the length direction of the plate; Step 3, rolling or bending: rolling or bending the multiple plates in step 2 according to the same curvature; Step 4, welding: splicing the multiple plates that have been rolled or bent in step 3 into a cylindrical body or a conical cylinder, and welding the spliced ​​parts; Step 5, overall bulging: placing a cylindrical body or a conical cylindrical body into a bulging mold, and using the bulging mold to perform overall bulging forming on the cylindrical body, the obtained profile includes a circumferential wavy profile, a conical end profile, a cylindrical profile connecting the circumferential wavy profile and the conical end profile, and a negative angle feature between the cylindrical profile and the circumferential wavy profile, wherein the taper angle of the conical end profile is A; Step 6, bending: using a roller mold to bend the tapered end surface in step 5 to obtain a partial arc segment connected to the cylindrical surface in the J-shaped outer flange, the roller mold includes an upper roller and a lower roller whose rotating axes are parallel, the axial end surface of the lower roller has a chamfer for forming the partial arc segment of the J-shaped outer flange, the gap between the upper roller and the lower roller is used to accommodate the tapered end surface, the rotating axes of the upper roller and the lower roller are along the radial direction of the cylinder or the tapered cylinder, and the upper roller and the lower roller move around the circumference of the cylinder or the tapered cylinder to implement the bending; Step seven, correction: Use a mold that is consistent with the J-shaped outer flange profile and has a negative angle feature to correct the J-shaped outer flange to obtain the accurate shape of the J-shaped outer flange.

2. The method for flanging a large-diameter thin-walled cylindrical part according to claim 1, characterized in that: In the step 1, the distances from the generatrix of the cylindrical surface to the crests and troughs in the wavy profile on the circumferential surface of the large-diameter thin-walled cylindrical part are equal.

3. The method for flanging a large-diameter thin-walled cylindrical part according to claim 1, characterized in that: In the step 2, the plate is divided into three equal pieces along the length direction of the plate.

4. The method for flanging a large-diameter thin-walled cylindrical part according to claim 1, characterized in that: In the step five, the bulging mold includes a male mold for the inner surface and a female mold for the outer surface, and both the male mold and the female mold are composed of multiple identical bulging petals, wherein the male mold is slidably connected to multiple inclined tracks distributed on a first circumference, and the female mold is slidably connected to multiple inclined tracks distributed on a second circumference, and the first circumference is concentric and coplanar with the second circumference and is located inside the second circumference.

5. The method for flanging a large-diameter thin-walled cylindrical part according to claim 1, characterized in that: In the step 5, the value of the taper angle A is 135°.

6. The method for flanging a large-diameter thin-walled cylindrical part according to claim 1, characterized in that: The process between step five and step six also includes trimming, in which the large end of the tapered end surface is cut to obtain the accurate length of the J-shaped outer flange.

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