A method for improving the uniformity of rib thickness of locally shear-formed high-rib thin-walled cylindrical components

Abstract

The present invention relates to the field of metal plastic processing technology, and discloses a method for improving the uniformity of the thickness of the ribs of high-rib thin-walled cylindrical components formed by local shearing, comprising: clamping the tube blank to the core shaft of a spinning machine by applying a radial constraint force; selecting a flow roller with a double-conical surface structure for flow spinning, controlling the flow roller to perform one-pass overall thinning on the tube body of the tube blank by its forming working surface, and then performing two-pass local thinning on part of the tube segment to form a stepped forming surface at the end of the two-pass local thinning tube segment; selecting a shearing roller for local shear forming, and using the bottom of the forming surface as the shearing starting position, controlling the shearing roller to perform axial shearing feeding on the unthinned tube segment to obtain an annular outer rib cylindrical component. The method of the present invention is simple, and further simplifies the process device compared to the existing technology. It not only achieves the improvement of the uniformity of the high-rib thickness, but also can meet the needs of multi-rib structural components and variable wall thickness components.

Description

Technical Field

[0001] The present invention relates to the technical field of metal plastic processing, and in particular to a method for improving the thickness uniformity of ribs of locally shear-formed high-rib thin-walled cylindrical components. Background Art

[0002] With the rapid development of aerospace and advanced weaponry, the demand for ribbed structural parts is increasing. Existing processes for forming thin-walled, annular, and ribbed cylindrical parts, due to their structural peculiarities, present significant limitations.

[0003] The Chinese patent with the patent number CN202111514553.5 discloses a shear forming method for annular outer rib cylindrical parts. The invention is based on the characteristics of local loading progressive (spinning) forming. The central axis of the shearing wheel is arranged at a certain angle to the axis of the core shaft, and the shear deformation is fully utilized to promote the flow of materials in the radial and axial directions. However, with the increase of the axial feed length, the wall thickness of the ribs is unevenly distributed. In the Chinese patent with the patent number 202211614009.2, a processing method for large thin-walled flanges is disclosed. In this method, an annular back pressure die is additionally provided on the basis of the shear forming process. This method requires the joint extrusion action of the back pressure die and the wheel to shape the formed rib structure. Due to the insufficient flexibility of the back pressure die, it is difficult to meet the needs of forming multiple rib components and variable wall thickness cylindrical wall components.

[0004] Chinese patent number CN202111514518.3 discloses a method for forming high-ribbed, thin-walled cylindrical parts using heat-assisted multi-rotor spinning. This method uses an external heat source to soften the blank, followed by segmented thinning using a flow-type spinning wheel. Finally, a shearing wheel is used to form the high-ribbed, thin-walled component. However, the softening of the material reduces the reflex effect of the new surface of the rib structure, making the rib structure susceptible to bending during the forming process.

[0005] In summary, the existing plastic forming process for cylindrical parts has certain limitations. Under the premise of ensuring uniform distribution of rib width, how to simplify the process equipment and simultaneously meet the forming conditions and working conditions of multiple conditions is an urgent problem to be solved. To this end, this patent proposes to first thin the cylindrical part blank as a whole, and then thin it in sections, making full use of the forming angle exit angle left by the flow roller on the blank, and using the material work hardening effect to reduce the fluctuation range of the main shear surface angle during the local shear forming process, thereby achieving the control of the uneven distribution of rib wall thickness. Summary of the Invention

[0006] Based on the above-mentioned technical problems, the present invention provides a method for improving the uniformity of the rib thickness of locally shear-formed high-rib thin-walled cylindrical components. The method is based on the local shear forming and flow spinning process of annular outer rib cylindrical parts. According to the characteristics of work hardening of the material during deformation, the active local loading deformation is combined with the passive material hardening. The distribution of rib width is improved under the premise of simplifying the process equipment, thereby achieving an improvement in the uniformity of high rib thickness.

[0007] To achieve the above object, the present invention provides a method for improving the uniformity of rib thickness distribution of locally shear-formed high-rib thin-walled cylindrical components, which comprises the following steps:

[0008] S1. Install the barrel:

[0009] Clamp the tube blank onto the mandrel of the spinning machine, and start the spinning machine to drive the tube blank to rotate synchronously with the mandrel;

[0010] S2, Flow Spinning:

[0011] A flow wheel with a double-conical surface structure is selected for flow spinning. The flow wheel includes a forming working surface and an exit working surface connected by a circular arc working surface. The feed angle of the forming working surface is α p , 15 degrees <α p <45 degrees; the flow wheel is controlled to first perform a first pass of overall thinning on the cylindrical blank, and then perform a second pass of local thinning on the cylindrical part, and a step-shaped forming surface is formed at the thinning feed end of the second pass of the local thinning section of the cylindrical section, and the angle α1 between the forming surface and the axial direction of the cylindrical blank is equal to α p ;

[0012] S3, shear forming:

[0013] A shearing wheel is selected for local shear forming. The angle between the upper shearing working surface and the lower shearing working surface of the shearing wheel is 90 degrees. The lower shearing working surface is fitted to the outer surface of the second-pass locally thinned cylinder segment. The bottom of the step of the forming surface in step S2 is used as the shear starting position. The shearing wheel is controlled to perform axial shear feed on the single-pass thinned cylinder segment. The shear feed direction is consistent with the thinning feed direction until the shear feed distance reaches the preset value to prepare a high-rib thin-walled cylindrical part.

[0014] As a further preferred technical solution of the present invention, in step S2, the overall thinning amount in one pass is 20% to 30% of the tube blank thickness, the total thinning amount of the two local thinning passes (the sum of the thinning amounts in the first and second passes) of the tube blank is 40% to 60% of the tube blank thickness, and the shear feed distance in step S3 is 3 to 8 times the total thinning amount. Further preferably, the overall thinning amount of the tube blank in the first pass is 20% of the tube blank thickness, the total thinning amount of the local thinning in the two passes is 60% of the tube blank thickness, and the shear feed distance is 6 to 7 times the thinning amount.

[0015] As a further preferred technical solution of the present invention, in step S2, the flow wheel first thins the tube blank as a whole, and then performs local thinning in a segmented thinning manner, so that a forming surface is formed at the end of each locally thinned tube segment along the local thinning feed direction, and through step S3, annular outer ribs can be formed at the thinning feed end of each locally thinned tube segment.

[0016] As a further preferred technical solution of the present invention, the exit angle of the exit working surface of the flow wheel is β p , β p If the angle is less than 30 degrees, the flow roller is controlled to feed in the opposite direction of the thinning feed in step S2 to shape the root of the annular outer rib formed in step S3 by exiting the working surface.

[0017] As a further preferred technical solution of the present invention, 10 degrees < β p <30 degrees.

[0018] As a further preferred technical solution of the present invention, there are multiple flow impellers, which are evenly arranged circumferentially around the tube blank. The multiple flow impellers operate synchronously during the flow spinning process to act on the tube blank at the same time.

[0019] The method of the present invention for improving the uniformity of the thickness of the ribs of a locally shear-formed high-rib thin-walled cylindrical component adopts the above technical solution and can achieve the following beneficial effects:

[0020] 1) The processing method provided by the present invention applies radial constraints to the cylindrical part, first performs overall thinning on the cylindrical blank by using a flow roller, and then performs secondary thinning at a preset special position, forming a step-shaped forming surface between the single-thinned cylindrical section and the secondary thinned cylindrical section of the cylindrical blank, and then uses the shearing roller to feed shear toward the single-thinned cylindrical section with the bottom of the forming surface as the shearing starting position, thereby forming a high-rib structure with uniform rib thickness distribution. Moreover, since the cylindrical part is first flow-spun before shearing and forming, the cylindrical part blank is hardened as a whole, and it is not easy to produce the defect of diameter expansion during the forming of the high-rib structure; when forming multiple rib structures, the exit surface after flow spinning can be fully utilized to reduce the problem of the widest root of the rib in the local shearing forming process.

[0021] 2) The method of the present invention is simple and further simplifies the process equipment compared with the existing technology. It not only improves the uniformity of high-rib thickness, but also meets the needs of multi-rib structural components and variable wall thickness components. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Figure 1 and Figure 2 This is a schematic diagram of the state in which the flow wheel of the present invention performs flow spinning on the tube blank.

[0024] Figure 3 This is a schematic diagram of the state in which the shearing wheel of the present invention performs local shearing and forming on the tube blank.

[0025] Figure 4 This is a schematic structural diagram of the flow impeller of the present invention;

[0026] Figure 5 A partially enlarged view of the flow wheel of the present invention;

[0027] Figure 6 Schematic diagram of the structure of the shear wheel of the present invention;

[0028] Figure 7 The annular outer rib cylindrical parts are obtained by processing the cylindrical blanks in Example 1 and Comparative Example 1 respectively, wherein a is the cross section of the second high rib structure; b is the cross section of the first high rib structure.

[0029] Figure 8 This is a diagram showing the influence of overall spinning on local shear forming components. It can be clearly seen that after overall thinning, the work hardening effect of the cylindrical blank plays an important role in improving the rib thickness.

[0030] In the figure: 1. tube blank, 2. core shaft, 3. flow wheel, 301. forming working surface, 302. arc working surface, 303. exit working surface, 4. shearing wheel, 401. upper shearing working surface, 402. lower shearing working surface, 5. forming surface.

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Terms such as "upper," "lower," "left," "right," "center," and "one" used in the embodiments are for ease of description and are not intended to limit the scope of the present invention. Changes or adjustments to these relative terms, without substantially altering the technical content, are also considered within the scope of the present invention.

[0033] Example 1

[0034] like Figure 1-3 This embodiment provides a method for improving the uniformity of rib thickness of a locally shear-formed high-rib thin-walled cylindrical component, specifically comprising the following steps:

[0035] S1. Install the barrel:

[0036] A cylindrical blank 1 with a wall thickness of t = 12 mm is clamped to the mandrel 2 of the spinning machine, and the spinning machine is started to drive the cylindrical blank 1 to rotate synchronously with the mandrel 2. The cylindrical blank can be fixed by radial constraint using an annular back pressure die, or other clamps can be used to fix the cylindrical blank. There is no limitation here, as long as the cylindrical blank 1 and the mandrel 2 can be relatively fixed and remain stable during the subsequent spinning process.

[0037] S2, Flow Spinning:

[0038] Select the flow wheel 3 with double cone structure (see Figure 4 and 5 As shown in FIG, the flow spinning is performed, the flow wheel 3 includes a forming working surface 301 and an exit working surface 303 connected by a circular arc working surface 302, and the feed angle α of the forming working surface p = 30 degrees; control the radial direction of the flow wheel 3 and the axial direction of the tube blank 1, first of all, the cylindrical blank is thinned as a whole (see Figure 1 As shown), the thinning amount is 2mm, and after pressing, the axial thinning feed is started until the overall wall thickness of the tube blank 1 becomes 10mm; then the thinned tube blank 1 is subjected to two local thinning passes (see Figure 2 As shown in FIG. 1 , the total thinning amount in a local area reaches 6 mm. While thinning the cylindrical part, a stepped forming surface 5 is formed at the thinning feed end of the second-pass locally thinned barrel section (i.e., the transition portion between the first-pass and second-pass locally thinned barrel sections). The angle α1 between the forming surface and the axial direction of the barrel blank 1 is equal to 30 degrees. Subsequently, the flow wheel 3 is withdrawn in the radial direction.

[0039] S3, local shear forming:

[0040] Select Shear Wheel 4 (see Figure 6As shown in FIG, local shear forming is performed, the angle between the upper shear working surface 401 and the lower shear working surface 402 of the shear wheel is 90 degrees, and the lower shear working surface is fitted to the outer surface of the thinned cylinder section (the shearing amount is equal to 40% (and 4mm) of the single thinning amount of the second local thinning area in step S2, and the corresponding relative shearing amount is 40%), and the bottom of the forming surface in step S2 (the outer surface of the cylinder that has been partially thinned) is used as the shear starting position ( Figure 3 ), control the shearing wheel to perform axial shearing feed on the unthinned cylinder section, and the shearing feed direction is consistent with the thinning feed direction, until the shearing feed distance reaches the preset value of 28mm, and radially withdraw the shearing wheel to prepare an annular outer rib cylindrical part with a first high rib structure, and remove the cylindrical part from the core mold.

[0041] Comparative Example 1

[0042] As a comparative experiment of Example 1, the cylindrical part with annular outer ribs formed in Example 1 was further processed to form a high-rib structure by using a traditional shearing process on the cylindrical section (with a wall thickness of 10 mm) that had not been locally thinned on the cylindrical blank. The specific operation was as follows:

[0043] Install the cylinder blank with reference to step S1 of Example 1, and position the cylinder section that has not been locally thinned on the cylinder blank on the outside;

[0044] The same shearing forming process as step S3 in Example 1 is selected, and the end of the non-locally thinned tube section of the tube blank is used as the shearing starting position. The shearing wheel is controlled to perform axial shearing feed on the non-thinned tube section. The shearing depth is consistent with the shearing thickness of 4mm in Example 1 (the relative shearing amount is 40%), until the shearing feed distance reaches the preset value of 28mm, so as to form a second high rib structure on the annular outer rib cylindrical part of Example 1.

[0045] The outer shape structure of the annular outer rib cylindrical member having the first high rib structure and the second high rib structure is as follows Figure 7 As shown, cross-sections of the first and second high-rib structures reveal that the first structure exhibits relatively uniform rib width, a significant improvement over the second structure. Furthermore, the barrel section at the location of the second structure exhibits a diameter expansion defect, with warping visible through the cross-section. In Comparative Example 1, during the shear forming of the high-rib structure, the barrel section is primarily formed through a process of diameter expansion and necking, which makes the barrel section susceptible to diameter expansion defects under these deformation conditions.

[0046] In a specific embodiment, in order to provide a plurality of first high rib structures on the annular outer rib cylindrical member, in step S2, the cylindrical blank is thinned in sections by a flow roller, and a plurality of locally thinned cylindrical sections are sequentially obtained along the thinning feeding direction, so that a forming surface is formed at the end of each locally thinned cylindrical section (see Figure 2As shown), then through step S3, annular outer ribs can be formed on each locally thinned barrel segment.

[0047] In another specific embodiment, the exit angle of the exit working surface of the flow wheel is β p , and β p Less than 30 degrees. After the first high rib structure is completed in step 3 of Example 1, the flow roller is controlled to feed in the opposite direction of the thinning feed in step S2 to reshape the root of the annular outer rib formed in step S3 by exiting the working surface. After the reshaping, the cylindrical member is removed. This can further improve the width of the rib root and prevent cracking of the strain-hardened material during shear deformation.

[0048] Comparative Example 2:

[0049] As a comparative experiment of Example 1, an original tube blank with a wall thickness of 10 mm was selected for direct local shear forming to compare the uniformity of the formed high-rib wall thickness. The specific operation steps are as follows:

[0050] Install the cylinder blank according to step S1 of Example 1;

[0051] The same shearing forming process as step S3 in Example 1 is selected, and the end of the tube blank is used as the shearing starting position. The shearing wheel is controlled to perform axial shearing feed. The shearing depth is consistent with the shearing thickness of 4mm in Example 1 (the relative shearing amount is 40%), until the shearing feed distance reaches the preset value of 28mm, so as to directly form a high-rib structure on the original tube blank that has not been thinned.

[0052] Comparison was made between the slices of the workpiece with high rib structure formed in Example 1 and Comparative Example 2. Figure 8 As shown in the figure, the rib structure formed by flow spinning, followed by local thinning, and finally shearing has significantly improved thickness uniformity from the rib tip to the rib root. Therefore, the present invention first thins the entire material to work harden it, and the work-hardened material has a significant advantage in uniformity when forming high-rib structures.

[0053] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for improving the uniformity of rib thickness of locally shear-formed high-rib thin-walled cylindrical components, characterized in that: The following steps are involved: S1. Install the barrel: Clamp the tube blank onto the mandrel of the spinning machine, and start the spinning machine to drive the tube blank to rotate synchronously with the mandrel; S2, Flow Spinning: A flow wheel with a double-conical surface structure is selected for flow spinning. The flow wheel includes a forming working surface and an exiting working surface connected by a circular arc working surface. The feed angle of the forming working surface is α p , 15 degrees <α p <45 degrees; the flow wheel is controlled to first perform a first pass of overall thinning on the cylindrical blank, and then perform a second pass of local thinning on the cylindrical part, and a step-shaped forming surface is formed at the thinning feed end of the second pass of the local thinning section of the cylindrical section, and the angle α1 between the forming surface and the axial direction of the cylindrical blank is equal to α p ; S3, shear forming: A shearing wheel is selected for local shear forming. The angle between the upper shearing working surface and the lower shearing working surface of the shearing wheel is 90 degrees. The lower shearing working surface is fitted to the outer surface of the second-pass locally thinned cylinder segment. The bottom of the step of the forming surface in step S2 is used as the shear starting position. The shearing wheel is controlled to perform axial shear feed on the single-pass thinned cylinder segment. The shear feed direction is consistent with the thinning feed direction until the shear feed distance reaches the preset value to prepare a high-rib thin-walled cylindrical part.

2. The method for improving the uniformity of rib thickness of locally shear-formed high-rib thin-walled cylindrical components according to claim 1, characterized in that: In step S2, the thinning amount of the overall thinning in one pass is 20% to 30% of the thickness of the tube blank, and the total thinning amount of the local thinning tube section in the second pass is 40% to 60% of the thickness of the tube blank; in step S3, the shear feed distance is 3 to 8 times the thinning amount.

3. The method for improving the uniformity of rib thickness of locally shear-formed high-rib thin-walled cylindrical components according to claim 1, characterized in that: In step S2, the flow roller first performs one-pass overall thinning on the tube blank, and then performs two-pass local thinning in a segmented thinning manner. Along the local thinning feed direction, a forming surface is formed at the end of each locally thinned tube segment. Through step S3, annular external ribs can be formed at the thinning feed end of each locally thinned tube segment.

4. The method for improving the uniformity of rib thickness of a locally sheared high-rib thin-walled cylindrical component according to claim 1, characterized in that: The exit angle of the exit working surface of the flow wheel is β p , β p If the angle is less than 30 degrees, the flow roller is controlled to feed in the opposite direction of the thinning feed in step S2 to shape the root of the annular outer rib formed in step S3 by exiting the working surface.

5. The method for improving the uniformity of rib thickness of a locally sheared high-rib thin-walled cylindrical component according to claim 4, characterized in that: 10 degrees < β p <30 degrees.

6. The method for improving the uniformity of rib thickness of a locally shear-formed high-rib thin-walled cylindrical component according to any one of claims 1 to 5, characterized in that: The rollers are symmetrically distributed on both sides of the cylindrical blank, and the multiple rollers are operated step by step during the forming process to act on the cylindrical blank at the same time.

Images