Integral forming method of inverted L-shaped rib cylindrical part

Abstract

The invention relates to the technical field of plastic processing of thin-wall parts, and discloses an integral forming method of an inverted L-shaped rib cylindrical part, which comprises the following steps of: firstly, performing shearing and spinning on a cylindrical part blank, and performing gradient heating on a rib part formed by shearing to prepare an approximately inverted L-shaped rib cylindrical part; and then axial shaping is conducted on the inverted L-shaped rib through a flat spinning wheel, and finally the inverted L-shaped rib cylindrical part is obtained. According to the overall forming method of the inverted-L-shaped rib cylindrical part, the rib height can be remarkably increased, cracking is restrained, technological parameters are convenient to adjust, and then the shape and size of the inverted-L-shaped rib cylindrical part are adjusted and controlled. By means of local loading of the two spinning rollers, the material is in the deformation state with the main shear deformation mode and the auxiliary upset-extrusion deformation mode, the rib height limit is remarkably improved, through introduction of a thermal field, dislocation rearrangement and polygon can happen to the structure through the dynamic recovery effect, the deformation resistance is reduced, and then rib cracking is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of plastic processing of thin-walled parts, and in particular to an integral forming method of a Γ-shaped rib cylindrical part. Background Art

[0002] Γ-ribbed cylindrical parts are thin-walled ribbed cylindrical parts with complex cross-sectional shapes, which are composed of thin-walled cylinders and annular Γ-shaped reinforcement ribs. The complex cross-sectional shape can effectively improve the strength and structural rigidity of the cylindrical parts, and significantly reduce the mass of the cylindrical parts, so it has attracted widespread attention in the fields of aerospace, transportation, etc. The characteristics and forming difficulties of this type of component mainly lie in the combination of its large diameter cylinder (m-level) and local complex Γ-ribs (cm-level).

[0003] For this type of components, the manufacturing methods currently mainly use mechanical processing or block forming and riveting / welding. Mechanical processing forms the required cross-section ribs by removing a large amount of material from the thick cylinder, which not only makes the material utilization rate low and increases the cost, but also cuts off the metal flow line, produces complex residual stress, causes shape distortion and microcrack initiation, and restricts the shape accuracy and fatigue life of the component. Block forming and riveting / welding means first dividing the component into a thin-walled cylinder and ribs that can be spun or simply machined, and then connecting the formed cylinder and ribs together by riveting or welding. This forming method not only has many steps, long process, and weight gain caused by rivets / welds, but also the residual stress at the connection part will greatly reduce the reliability and fatigue life of the component. With the continuous improvement of the requirements of high-end equipment such as aerospace vehicles for lightweight, high performance, high reliability and long life, it is necessary to develop new manufacturing processes to achieve high-precision and high-performance integral forming of Γ-shaped rib cylindrical parts.

[0004] In the prior art, there are high-precision and high-performance integral forming methods for ribbed cylindrical parts. In the Chinese patent application document with application number 202111514553.5, a shear forming method for annular outer rib cylindrical parts is disclosed. This method uses axial loading of the shear wheel to shear and separate the material, and transfer it radially to form ribs. The formed ribs have the advantage of a large aspect ratio, but the cross-sectional shape is I-type. In the Chinese patent application document with application number 202310239465.1, a step-by-step shear forming method for T-ribbed cylindrical parts is disclosed. This method realizes the forming of complex T-section ribs through multi-directional collaborative loading of multiple wheels such as shear wheels, flow wheels and fractal wheels, but is not suitable for the forming of Γ-section ribs. The Chinese patent application document with application number 202110974901.0 discloses a method for rotary extrusion of a reinforced cylindrical shell. This method uses hot spinning to fill the material into the rib groove of the core mold, and improves the rib height limit and overall performance of the ribbed parts through multiple heat treatments. However, it is only suitable for the forming of ribs inside I-sections, and has high requirements for the spinning core mold, making it difficult to extend to Γ-shaped ribbed cylindrical parts.

[0005] In summary, the existing integral forming method of ribbed cylindrical parts can only realize the forming of I-shaped and T-shaped cross-section ribbed cylindrical parts, and there are problems such as uneven hardness distribution of the ribs and easy cracking of the rib top. Therefore, it is necessary to propose an integral forming method for Γ-shaped ribbed cylindrical parts, so as to broaden the application of such components. Summary of the invention

[0006] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides an integral forming method of a Γ-shaped rib cylindrical part, which can not only significantly increase the rib height and inhibit cracking, but also facilitate the adjustment of process parameters, thereby realizing the regulation of the shape and size of the Γ-shaped rib cylindrical part.

[0007] To achieve the above object, the present invention provides a method for integrally forming a Γ-shaped rib cylindrical part, which comprises the following steps:

[0008] S1, installing the core mold on the mandrel of the spinning machine, clamping the positioning sleeve on the core mold, clamping the cylindrical blank on the core mold and positioning it using the positioning sleeve, installing the shearing wheel and the horizontal wheel on the wheel frame of the spinning machine respectively, and assembling the flame spray gun on the spinning machine;

[0009] Among them, the initial wall thickness tb0 of the cylindrical blank satisfies the formula: , where D0 is the outer diameter of the cylindrical blank and d0 is the inner diameter of the cylindrical blank;

[0010] S2. Start the spinning machine, let the mandrel drive the cylindrical blank to rotate, and control the shearing wheel to the preset shearing depth a. p∈[0.2tb0,0.5tb0] feed f in the axial direction, f≥30mm; then control the shearing wheel to withdraw in the radial direction, and use a flame spray gun to heat the ribs formed by shearing in a gradient manner during shearing and spinning, wherein the forming temperature of the rib top is 100℃~800℃, and the forming temperature of the rib bottom is below 200℃ and lower than the forming temperature of the rib top, so as to prepare a nearly Γ-shaped rib cylindrical part;

[0011] S3, continuing the rotating state of the cylindrical blank and the heating state of the rib portion by the flame spray gun in step S2, controlling the flat rotary wheel to feed axially according to the preset rib height h of the Γ-shaped rib until the rotary wheel and the rib portion are no longer in contact, and then controlling the flat rotary wheel to withdraw radially, and finally preparing a Γ-shaped rib cylindrical part;

[0012] In the above steps, the parameters related to forming the Γ-shaped rib cylindrical part respectively meet the following conditions:

[0013] t1<3.28a p ;

[0014] t2≤t1;

[0015]

[0016] d1≥d0;

[0017] dt1≥dt0;

[0018] L1 ≥ L0;

[0019]

[0020] Among them, t1 is the web width of the Γ-shaped rib, t2 is the flange width of the Γ-shaped rib, h is the rib height of the Γ-shaped rib, w is the rib width of the Γ-shaped rib, D1 is the outer diameter of the Γ-shaped rib cylindrical part, d1 is the inner diameter of the Γ-shaped rib cylindrical part, dt1 is the outer diameter of the positioning step in the Γ-shaped rib cylindrical part, L1 is the length of the Γ-shaped rib cylindrical part, tb1 is the wall thickness of the formed area of ​​the Γ-shaped rib cylindrical part, dt0 is the outer diameter of the positioning step in the cylindrical blank, L0 is the length of the cylindrical blank, a p is the preset shearing depth and f is the axial feed distance.

[0021] As a further preferred technical solution of the present invention, the height of the positioning sleeve is less than or equal to the rib height of the Γ-shaped rib.

[0022] As a further preferred technical solution of the present invention, a positioning step is processed at the rear end of the cylindrical blank, and the height s of the positioning step is slightly smaller than the height of the groove on the positioning sleeve.

[0023] As a further preferred technical solution of the present invention, the shearing wheel includes an upper working surface and a lower working surface with an angle of 90° between them, and the upper and lower working surfaces are connected by a transition fillet with a radius of 0.5 to 1.5 mm; and / or, the installation angle of the shearing wheel relative to the core shaft is 45°.

[0024] As a further preferred technical solution of the present invention, the flat rotating wheel includes a right working surface and a lower working surface with an angle of 90° between them, and the right and lower working surfaces are connected by a transition fillet with a radius of 1 to 5 mm; and / or, the installation angle of the flat rotating wheel relative to the core shaft is 90°.

[0025] As a further preferred technical solution of the present invention, the number of the shearing wheels and the flat wheels are both two.

[0026] As a further preferred technical solution of the present invention, in step S2, the spindle speed is 30-90 rpm, and the shear wheel feed speed is 0.1-1.5 mm / s.

[0027] As a further preferred technical solution of the present invention, in step S3, the feeding speed of the flat-rotating wheel is 0.1-2.5 mm / s.

[0028] Compared with the prior art, the beneficial effects achieved are:

[0029] 1. The present invention proposes an integral forming method for a Γ-shaped rib cylindrical part, which uses two types of rollers to locally load the material so that the material is in a deformation state in which the shear deformation mode is dominant and the upsetting deformation mode is auxiliary, thereby significantly improving the rib height limit;

[0030] 2. The present invention proposes a method for integrally forming a Γ-shaped rib cylindrical part, which introduces a thermal field to enable the organization to undergo a dynamic recovery effect, causing dislocation rearrangement and polygonization, thereby reducing deformation resistance and preventing cracking of the ribs;

[0031] 3. The present invention proposes a method for integrally forming a Γ-shaped rib cylindrical part, which includes a positioning sleeve, a shearing wheel and a flat wheel. The method has a simple structure, is easy to install, and is convenient to operate, thereby improving the flexibility of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0033] Figure 1 It is a schematic diagram of the integral forming process of a Γ-shaped rib cylindrical part;

[0034] Figure 2 It is a structural schematic diagram of the positioning sleeve;

[0035] Figure 3 is a schematic diagram of the structure of the shear wheel;

[0036] Figure 4 It is a schematic diagram of the structure of the flat-rotating wheel;

[0037] Figure 5 It is a schematic diagram of the structural dimensions of the blank;

[0038] Figure 6 It is a schematic diagram of the structural dimensions of a Γ-shaped rib cylindrical part;

[0039] Figure 7 It is a Γ-shaped rib cylindrical member formed in a row in Example 1;

[0040] Figure 8 The utility model relates to an I-shaped rib cylindrical part formed by an existing method.

[0041] In the figure: 1. mandrel; 2. core mold; 3. positioning sleeve; 4. blank; 5. shearing wheel; 6. I-shaped rib cylindrical part; 7. nearly Γ-shaped rib cylindrical part; 8. flat wheel; 9. Γ-shaped rib cylindrical part; 10. threaded hole; 11. through hole; 12. slot; 13. upper working surface; 14. lower working surface; 15. right working surface; 16. lower working surface; 17. positioning step.

[0042] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The terms such as "upper", "lower", "left", "right", "middle" and "one" cited in the preferred embodiments are only for the convenience of description, and are not used to limit the scope of the present invention. The change or adjustment of the relative relationship shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0044] Embodiment 1:

[0045] like Figure 1 As shown, the embodiment provides a method for integrally forming a Γ-shaped rib cylindrical part, comprising the following steps:

[0046] S1. Install the mold and blank

[0047] A universal core mold 2 (inner diameter 201 mm) is installed on the core shaft 1 of the spinning machine, lubricant is applied on the core mold 2, a positioning sleeve 3 (inner diameter 201 mm, height 30 mm) is clamped on the universal core mold 2, a cylindrical blank 4 (inner diameter 201 mm, wall thickness 20 mm, length 98 mm) made of 6061 aluminum alloy is clamped on the universal core mold 2 and the positioning sleeve 3, a shearing wheel 5 (wheel corner radius 0.5 mm) and a flat wheel 8 (wheel corner radius 2 mm) are respectively installed on the wheel frame of the spinning machine, and a flame spray gun (one) is assembled on the spinning machine.

[0048] In step S1, the structure of the positioning sleeve 3 is as follows Figure 2 As shown, the reserved threaded hole 10 is used to connect the petaled positioning sleeve to increase the total height of the positioning sleeve and improve the rib height limit of the Γ-shaped rib proposed by the present invention; the through hole 11 is used to fix the positioning sleeve 3 to the core mold 2; the slot 12 is used to fix the cylindrical blank 4 to the positioning sleeve 3. The structure of the cylindrical blank 4 is as shown in FIG. Figure 3 As shown, the positioning step 17 is used to fix the cylindrical blank 4 to the positioning sleeve 3, D0 is the outer diameter of the cylindrical part, d0 is the inner diameter of the cylindrical part, L0 is the length of the cylindrical part, dt0 is the outer diameter of the positioning step, s is the depth of the positioning step, and c is the length of the positioning step.

[0049] S2. Shearing and forming I-type rib tube → Shearing and forming nearly Γ-type rib tube → Shearing wheel exit

[0050] Start the spinning machine, let the core shaft 2 drive the 6061 aluminum alloy cylindrical blank 4 to rotate (rotation speed 60rpm), control the shear wheel 5 to feed 80mm in the axial direction according to the process parameters of shear depth 6mm and feed speed 0.5mm / s, and then control the shear wheel to withdraw in the radial direction according to the process parameters of feed speed 0.5mm / s. At the same time, use a flame spray gun to perform gradient heating on the ribs, that is, the heating temperature of the top of the rib is high (the temperature of the top of the rib is about 250℃) and the heating temperature of the bottom of the rib is low (the temperature of the bottom of the rib is about 100℃). The I-shaped rib formed by shearing is heated by gradient heating. At this time, the top of the I-shaped rib will undergo dynamic recovery, reducing the deformation resistance and stiffness of the material, while the bottom of the I-shaped rib is mainly affected by work hardening, with a low degree of dynamic recovery and a large stiffness of the rib. Therefore, under the axial loading of the wheel, the rib will tilt toward the free surface side, thereby preparing a nearly Γ-shaped rib cylindrical part 7.

[0051] In step S2, the structure of the shearing wheel 5 is as follows: Figure 4 As shown, the shearing wheel includes an upper working surface 13 and a lower working surface 14 with an angle of 90° between them. The upper working surface 13 and the lower working surface 14 are connected by a transition fillet with a radius of 0.5 mm. The installation angle of the shearing wheel relative to the core shaft is 45°.

[0052] In step S2, the flame spray gun is located on one side of the cylindrical part close to the core shaft 2, the flame is aimed at the top of the rib and gradually moves outward as the rib grows, and the temperature of the rib is monitored in real time by an infrared thermal imager to ensure that the temperature of the rib is in a preset state and range.

[0053] It is worth noting that in this processing process, the cylindrical blank 4 is first sheared to form an I-rib cylindrical part 6, and then when the axial feed distance of the shearing wheel 5 is about 30 mm, the cylindrical blank 4 is transformed from an I-rib cylindrical part 6 to a nearly Γ-rib cylindrical part 7.

[0054] S3, flat wheel feed → axial shaping to form Γ-shaped rib tube → flat wheel exit → unloading

[0055] Continuing the rotating state of the cylindrical blank and the heating state of the rib portion by the flame spray gun in step S2, the flat-rotating wheel 8 is controlled to feed 100 mm in the axial direction according to the process parameters of the rib height of the Γ-shaped rib of 30 mm and the feed speed of 0.5 mm / s, and then the flat-rotating wheel is controlled to withdraw in the radial direction according to the process parameters of the feed speed of 0.5 mm / s to prepare the Γ-shaped rib cylindrical part 9. Finally, the Γ-shaped rib cylindrical part 9 is taken out from the spinning machine, and then through mechanical processing and heat treatment, the shape, size and overall performance of the Γ-shaped rib cylindrical part can be further adjusted.

[0056] In step S3, the structure of the flat-rotating wheel 8 is as follows: Figure 5 As shown, the flat-rotating wheel includes a right working surface 15 and a lower working surface 16 with an angle of 90° between them. The right working surface 15 and the lower working surface 16 are connected by a transition fillet with a radius of 2 mm. The installation angle of the flat-rotating wheel relative to the core shaft is 90°.

[0057] The structure of the finally formed Γ-shaped rib cylindrical member 9 is as follows: Figure 6 As shown, D1 is the outer diameter of the cylindrical part, d1 is the inner diameter of the cylindrical part, L1 is the length of the cylindrical part, dt0 is the outer diameter of the positioning step, h is the rib height of the Γ-shaped rib, w is the rib width of the Γ-shaped rib, t1 is the web width of the Γ-shaped rib, and t2 is the wing width of the Γ-shaped rib.

[0058] like Figure 7 As shown, it can be seen that the surface quality of the Γ-shaped ribs of the finally formed Γ-shaped rib cylindrical part is good, without macro cracks and defects.

[0059] Comparative Example 1:

[0060] As a control experiment of Example 1, based on the preparation method of Example 1, the gradient heating operation of step 2 was omitted, and the same tooling and forming parameters were used to process the same blank. The I-shaped rib cylindrical part was formed by axial shearing in step 2 (gradient heating omitted). However, compared with Example 1, the total amount of material deformation and axial feed distance required for the Γ-shaped rib cylindrical part were larger, and cracking occurred when the axial feed distance was about 80 mm, as shown in FIG. Figure 8 In addition, if an I-shaped rib cylindrical part is formed at a smaller axial feed distance (such as 54 mm), and then axial shaping is continued according to step 3 of Example 1, the top of the rib will crack due to the excessive total deformation, and ultimately a Γ-shaped rib cylindrical part cannot be formed. In summary, the gradient heating shear forming method for Γ-shaped rib cylindrical parts proposed in the present invention can achieve the overall forming of Γ-shaped rib cylindrical parts and improve the forming limit of Γ-shaped ribs.

[0061] 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 integrally forming a Γ-shaped rib cylindrical part, characterized in that: The following steps are involved: S1, installing the core mold on the mandrel of the spinning machine, clamping the positioning sleeve on the core mold, clamping the cylindrical blank on the core mold and positioning it using the positioning sleeve, installing the shearing wheel and the horizontal wheel on the wheel frame of the spinning machine respectively, and assembling the flame spray gun on the spinning machine; Among them, the initial wall thickness tb0 of the cylindrical blank satisfies the formula: , where D0 is the outer diameter of the cylindrical blank and d0 is the inner diameter of the cylindrical blank; S2. Start the spinning machine, let the mandrel drive the cylindrical blank to rotate, and control the shearing wheel to the preset shearing depth a. p ∈[0.2tb0,0.5tb0], feed f in the axial direction, and then control the shearing wheel to withdraw in the radial direction. During the shearing and spinning, the ribs formed by shearing are heated by a flame spray gun in a gradient manner, wherein the forming temperature of the rib top is 100℃~800℃, and the forming temperature of the rib bottom is below 200℃ and lower than the forming temperature of the rib top, so as to prepare a nearly Γ-shaped rib cylindrical part; Among them, the axial feed distance of the shearing wheel f≥30mm; S3, continuing the rotating state of the cylindrical blank and the heating state of the rib portion by the flame spray gun in step S2, controlling the flat rotary wheel to feed axially according to the preset rib height h of the Γ-shaped rib until the rotary wheel and the rib portion are no longer in contact, and then controlling the flat rotary wheel to withdraw radially, and finally preparing a Γ-shaped rib cylindrical part; In the above steps, the parameters related to forming the Γ-shaped rib cylindrical part respectively meet the following conditions: t1<3.28a p ; t2≤t1; d1≥d0; dt1≥dt0; L1 ≥ L0; Among them, t1 is the web width of the Γ-shaped rib, t2 is the flange width of the Γ-shaped rib, h is the rib height of the Γ-shaped rib, w is the rib width of the Γ-shaped rib, D1 is the outer diameter of the Γ-shaped rib cylindrical part, d1 is the inner diameter of the Γ-shaped rib cylindrical part, dt1 is the outer diameter of the positioning step in the Γ-shaped rib cylindrical part, L1 is the length of the Γ-shaped rib cylindrical part, tb1 is the wall thickness of the formed area of ​​the Γ-shaped rib cylindrical part, dt0 is the outer diameter of the positioning step in the cylindrical blank, L0 is the length of the cylindrical blank, a p is the preset shearing depth and f is the axial shearing feed distance.

2. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: The height of the positioning sleeve is less than or equal to the rib height of the Γ-shaped rib.

3. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: A positioning step is processed at the rear end of the cylindrical blank, and the height s of the positioning step is slightly smaller than the height of the clamping groove on the positioning sleeve.

4. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: The shearing wheel comprises an upper working surface and a lower working surface with an angle of 90° therebetween, the upper and lower working surfaces are connected by a transition fillet with a radius of 0.5 to 1.5 mm; and / or, the installation angle of the shearing wheel relative to the mandrel is 45°.

5. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: The flat rotating wheel comprises a right working surface and a lower working surface with an included angle of 90° therebetween, the right and lower working surfaces are connected by a transition fillet with a radius of 1 to 5 mm; and / or, the installation angle of the flat rotating wheel relative to the mandrel is 90°.

6. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: The number of the shearing wheels and the translational wheels are both two.

7. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: In step S2, the spindle speed is 30-90 rpm, and the shear wheel feed speed is 0.1-1.5 mm / s.

8. The integral forming method of a Γ-shaped rib cylindrical part according to claim 1, characterized in that: In step S3, the feeding speed of the flat-rotating wheel is 0.1 to 2.5 mm / s.

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