A process for forming internal ribs in thin-walled lightweight alloy cylindrical components

Abstract

This invention discloses a forming process for the inner ribs of a thin-walled lightweight alloy cylindrical component. The steps include: stacking the layers of segmented molds one by one inside the cavity of the cylindrical blank, and controlling only one layer of segmented molds to be heated to a suitable temperature and then moved radially outward each time. This invention achieves continuous and precise forming of the annular inner ribs of the thin-walled lightweight alloy cylindrical component. The resulting annular inner ribs have no sharp edges on their inner walls, and their cross-section is a high-precision rectangular structure. The thin-walled lightweight alloy cylindrical component formed using this invention does not require trimming or straightening, and the resulting component is crack-free.

Description

Technical Field

[0001] This invention belongs to the field of precision forming technology for thin-walled light alloy components, specifically relating to a forming process for internal ribs of thin-walled light alloy cylindrical components. Background Technology

[0002] Typical thin-walled lightweight alloy components, such as thin-walled magnesium alloy components and thin-walled aluminum alloy components, are widely used in aerospace equipment. For thin-walled (main body wall thickness not greater than 3mm) lightweight alloy cylindrical components, in order to achieve precision forming, multi-step forming is usually required. The entire component needs to be repeatedly heated as a whole, which will lead to grain growth and performance degradation. Moreover, the component will cool down during the process of transferring from the heating furnace to the press after overall heating, resulting in very serious heat loss and making it prone to deformation and cracking.

[0003] In actual processing, thin-walled lightweight alloy cylindrical components with cylindrical inner cavities are relatively easy to form. However, for thin-walled lightweight alloy cylindrical components with cylindrical inner cavities and annular inner ribs, it is difficult to directly produce high-precision products. Generally, a step-by-step forming process combined with trimming and straightening is used. One of the difficulties in the processing is the poor precision of the formed annular inner ribs. For a cylindrical component with an outer diameter of 300mm, the inner diameter error of the annular inner ribs (with an inner diameter of 286mm) can be as high as 3-4mm, and the inner wall of the annular inner ribs is prone to sharp edges. Summary of the Invention

[0004] In order to at least solve the technical problems mentioned in the background art, the present invention provides a process for forming internal ribs of thin-walled light alloy cylindrical components.

[0005] The technical solution of the present invention is as follows.

[0006] A process for forming internal ribs in a thin-walled lightweight alloy cylindrical component includes the following steps:

[0007] Step 1: Fix the cylindrical blank onto the rotating platform;

[0008] Step 2: Stack the segmented mold layers one by one inside the cylindrical billet cavity. The outer wall of the mold is lubricated with oil. The mold includes a first layer of segmented mold, a second layer of segmented mold, and a third layer of segmented mold arranged sequentially from bottom to top. The outer wall of the segmented mold in the middle layer is provided with an annular mold cavity. The shape of the annular mold cavity is consistent with the shape of the inner rib of the thin-walled light alloy cylindrical component. Each layer of segmented mold is provided with a conical hole for fitting the extruded part. Each layer of segmented mold is provided with an independently controllable electric heating wire. Each layer of segmented mold is composed of 3-4 segments. The outer wall of each layer of segmented mold is an arc surface adapted to the inner cavity of the cylindrical billet.

[0009] Step 3: Only control the heating of the first layer of segmented mold. After heating to the set temperature, keep the temperature constant. Then control the extrusion part of the first layer of segmented mold to move axially downward, so as to realize the radial outward movement of the segmented body of the first layer of segmented mold. At the same time, control the rotating platform to rotate at a preset speed. After extrusion is in place, the top pressure rod is removed and the corresponding heating system is turned off.

[0010] Step 4: Only control the heating of the third layer segmented mold. After heating to the set temperature, keep the temperature constant. Fix the first layer segmented mold. Then control the extrusion part of the third layer segmented mold to move downward along the axis, so as to realize the radial outward movement of the segmented body of the third layer segmented mold. At the same time, control the rotating platform to rotate at the preset speed. After extrusion is in place, remove the top pressure rod and the extrusion part, and turn off the corresponding heating system.

[0011] Step 5: Only control the heating of the second layer segmented mold. After heating to the set temperature, keep the temperature constant. Fix the third layer segmented mold. Then control the extrusion part of the second layer segmented mold to move axially downward to realize the radial outward movement of the segmented body of the second layer segmented mold. At the same time, control the rotating platform to rotate at a preset speed. After extrusion is in place, remove the top pressure rod and turn off the corresponding heating system.

[0012] Step 6: Exit each layer of the segmented mold.

[0013] As a preferred option, the rotation speed of the rotating platform is 8000-10000 r / min.

[0014] As a preferred option, the cross-section of the annular mold cavity is rectangular, and the depth and height of the annular mold cavity are both no more than 10mm.

[0015] Furthermore, it also includes a fourth layer of segmented molds and a fifth layer of segmented molds arranged sequentially from bottom to top, with the fourth layer of segmented molds located above the third layer of segmented molds; it also includes:

[0016] Step 51: Only control the heating of the fourth layer segmented mold. After heating to the set temperature, keep the temperature constant. Fix the third layer segmented mold. Then control the extrusion part of the fourth layer segmented mold to move downward along the axis to realize the radial outward movement of the segmented body of the fourth layer segmented mold. At the same time, control the rotating platform to rotate at a preset speed. After extrusion is in place, remove the top pressure rod and turn off the corresponding heating system.

[0017] Step 52: Only control the heating of the fifth layer segmented mold. After heating to the set temperature, keep the temperature constant. Fix the fourth layer segmented mold. Then control the extrusion part of the fifth layer segmented mold to move downward axially, so as to realize the radial outward movement of the segmented body of the fifth layer segmented mold. At the same time, control the rotating platform to rotate at a preset speed. After extrusion is in place, remove the top pressure rod and turn off the corresponding heating system.

[0018] As a preferred embodiment, the thin-walled lightweight alloy cylindrical component is an aluminum alloy cylindrical component with a wall thickness of no more than 5 mm.

[0019] As a preferred option, the axial downward movement speed of each extrusion part is 0.5-1 mm / s.

[0020] Furthermore, in each step, the rotating platform rotates repeatedly in a pattern of "clockwise rotation for 5-8 seconds - counterclockwise rotation for 5-8 seconds".

[0021] Beneficial effects: This invention uses a layered, segmented mold combined with a high-speed rotating process to achieve continuous and precise forming of the annular inner ribs of thin-walled light alloy cylindrical components. The inner diameter error of the annular inner ribs of the resulting thin-walled light alloy (aluminum alloy) cylindrical components can be controlled within 1mm. The inner sidewall of the resulting annular inner ribs has no sharp edges, and its cross-section is a high-precision rectangular structure. The thin-walled light alloy cylindrical components formed using the scheme of this invention do not require trimming or straightening, and the processed components are free from cracks. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the initial state of the mold placed in the blank in Example 1;

[0023] Figure 2 This is a schematic diagram showing the radial outward movement of the segmented body of the first layer segmented mold in Example 1;

[0024] Figure 3 This is a schematic diagram showing the radial outward movement of the segmented body of the third-layer segmented mold in Example 1;

[0025] Figure 4 This is a schematic diagram showing the radial outward movement of the segmented body of the second-layer segmented mold in Example 1;

[0026] Figure 5 This is a schematic diagram showing the radial outward movement of the segmented body of the fourth-layer segmented mold in Example 1;

[0027] Figure 6 This is a schematic diagram showing the radial outward movement of the segmented body of the fifth-layer segmented mold in Example 1;

[0028] Figure 7 for Figure 1 A top-down diagram. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings. Example

[0030] A forming process for the inner rib of a thin-walled lightweight alloy cylindrical component is used to prepare a shell (made of magnesium-lithium alloy) with a main body wall thickness of 4mm. The inner wall of this aircraft has a ring-shaped inner rib 8 (e.g., Figure 4As shown), the annular inner rib 8 has a cross-sectional width of 8mm and a height of 6mm, and its corners have rounded chamfers. It is made of aluminum alloy. The steps include:

[0031] Step 1: Fix the cylindrical blank 9 onto the rotating platform;

[0032] Step 2, as follows Figure 1 and Figure 7 As shown, the segmented molds are stacked layer by layer inside the cylindrical blank 10. The mold includes, from bottom to top, a first layer of segmented mold 1, a second layer of segmented mold 2, a third layer of segmented mold 3, a fourth layer of segmented mold 4, and a fifth layer of segmented mold 5. The outer wall of the segmented molds in the middle layers has an annular cavity 10. In this example, only the outer wall of the second layer of segmented mold 2 has an annular cavity 10. The shape of the annular cavity 10 is consistent with the shape of the thin-walled light alloy cylindrical component. The ribs have a consistent shape, and the cross-section of the annular mold cavity 10 is rectangular. The depth of the annular mold cavity 10 is 8mm and the height is 6mm. Each layer of the segmented mold is provided with a conical hole 11. All conical holes are arranged coaxially. The conical holes 11 are used to fit the extruded part. Each layer of the segmented mold is provided with an independently controllable electric heating wire 13. Each layer of the segmented mold is composed of 3 segments. The outer wall of each layer of the segmented mold is an arc surface that fits the inner cavity of the cylindrical blank 10, that is, the inner wall of the cylindrical blank 10.

[0033] Step 3, as follows Figure 2 As shown, only the first layer of segmented mold 1 is heated. After heating to the set temperature (250℃), the temperature is kept constant. Then, the extrusion part 21 of the first layer of segmented mold 1 is controlled to move axially downward. The axial downward movement speed of the extrusion part 21 is controlled to be 1mm / second, so as to realize the radial outward movement of the segmented body of the first layer of segmented mold 1. At the same time, the rotating platform is controlled to rotate at a preset speed (9000 rpm). After extrusion is in place, the top pressure rod is withdrawn, and the corresponding heating system is turned off (that is, the electric heating system of the first layer of segmented mold 1 is turned off).

[0034] Step 4, as follows Figure 3 As shown, only the heating of the third-layer segmented mold 3 is controlled. After heating to the set temperature (250℃), the temperature is kept constant. The first-layer segmented mold 1 is fixed. Then, the extrusion part 23 of the third-layer segmented mold 3 is controlled to move axially downward. The axial downward movement speed of the extrusion part 23 is controlled to 1mm / second, so as to realize the radial outward movement of the segmented body of the third-layer segmented mold 1. At the same time, the rotating platform is controlled to rotate at a preset speed (9000 rpm). After extrusion is in place, the top pressure rod and the extrusion part 23 are removed, and the corresponding heating system is turned off (that is, the electric heating system of the third-layer segmented mold 3 is turned off).

[0035] Step 5, as follows Figure 4As shown, only the second-layer segmented mold 2 is heated. After heating to the set temperature (300℃), the temperature is kept constant. The third-layer segmented mold 3 is fixed. Then, the extrusion part 22 of the second-layer segmented mold 2 is axially moved downward. The axial downward movement speed of the extrusion part 22 is controlled to 1mm / second, so as to realize the radial outward movement of the segmented body of the second-layer segmented mold 2. At the same time, the rotating platform is controlled to rotate at a preset speed (10000 rpm). After extrusion is in place, the top pressure rod is removed, and the corresponding heating system is turned off (i.e., the electric heating system of the second-layer segmented mold 2 is turned off).

[0036] Step 51, as follows Figure 5 As shown, only the fourth layer segmented mold 4 is heated. After heating to the set temperature, the temperature (250℃) is kept constant. The third layer segmented mold 3 is fixed. Then, the extrusion part 24 of the fourth layer segmented mold 4 is controlled to move axially downward. The axial downward movement speed of the extrusion part 24 is controlled to be 0.5mm / second, so as to realize the radial outward movement of the segmented body of the fourth layer segmented mold 4. At the same time, the rotating platform is controlled to rotate at a preset speed (8000 rpm). After extrusion is in place, the top pressure rod is removed, and the corresponding heating system is turned off (i.e., the electric heating system of the fourth layer segmented mold 4 is turned off).

[0037] Step 52, as follows Figure 6 As shown, only the fifth-layer segmented mold 5 is heated. After heating to the set temperature (250℃), the temperature is kept constant. The fourth-layer segmented mold 4 is fixed. Then, the extrusion piece 25 of the fifth-layer segmented mold 5 is axially moved downward. The axial downward movement speed of the extrusion piece 25 is controlled at 0.5mm / second to achieve radial outward movement of the segmented body of the fifth-layer segmented mold 5. At the same time, the rotating platform is controlled to rotate at a preset speed. After extrusion is in place, the top pressure rod is removed, and the corresponding heating system is turned off (i.e., the electric heating system of the fifth-layer segmented mold 5 is turned off).

[0038] Step 6: Exit each layer of the segmented mold.

[0039] In steps 3 to 52, the rotating platform rotates repeatedly in the manner of "5 seconds forward rotation - 5 seconds reverse rotation..." until the lower end of the extruded part is aligned with the lower end of the corresponding layer of the segmented mold. Taking step 3 as an example, after the extruded part 21 is inserted into the conical hole of the first layer of the segmented mold 1, the rotating platform is immediately controlled to rotate forward at a preset speed for 5 seconds, while the extruded part 21 is controlled to move downward at a uniform speed. After rotating forward for 5 seconds, the rotating platform is immediately switched to reverse rotation for 5 seconds. During the uniform downward movement of the extruded part 21, the rotating platform is always controlled to rotate forward first and then reverse, until the bottom end of the extruded part 21 is aligned with the lower end of the first layer of the segmented mold 1.

[0040] In this embodiment, when the extruder is flush with the lower end of the segmented mold of the corresponding layer, the gap between adjacent segments of the segmented mold is no more than 5mm.

[0041] The thin-walled lightweight alloy cylindrical component formed in this embodiment was inspected. The results were as follows: The inner diameter of the annular inner rib 8 at eight points was measured with vernier calipers and was 286.1 mm, 285.7 mm, 286.4 mm, 285.9 mm, 286.5 mm, 286.2 mm, 286.4 mm, and 285.8 mm, respectively; The thickness (height) of the annular inner rib 8 at eight points was measured with vernier calipers and was 5.88 mm, 5.75 mm, 5.92 mm, 5.95 mm, 5.79 mm, 5.90 mm, 5.87 mm, and 5.95 mm, respectively.

[0042] In this embodiment, a layered, segmented mold combined with a high-speed rotating process enables continuous and precise forming of the annular inner ribs of the thin-walled lightweight alloy cylindrical component. The inner diameter error of the annular inner ribs of the resulting thin-walled lightweight alloy (aluminum alloy) cylindrical component can be controlled within 1 mm. The inner sidewall of the resulting annular inner ribs has no sharp edges, and its cross-section is a high-precision rectangular structure. The thin-walled lightweight alloy cylindrical component formed using this method does not require trimming or straightening, and the processed component is free from cracks.

Claims

1. A process for forming internal ribs in a thin-walled lightweight alloy cylindrical component, characterized by the following steps: include: Step 1: Fix the cylindrical blank onto the rotating platform; Step 2: Stack the various layers of the segmented molds one by one inside the cylindrical blank cavity; wherein, the mold includes a first layer of segmented mold (1), a second layer of segmented mold (2), and a third layer of segmented mold (3) arranged sequentially from bottom to top. The outer wall of the segmented mold in the middle layer is provided with an annular mold cavity (10). The shape of the annular mold cavity (10) is consistent with the shape of the inner rib of the thin-walled light alloy cylindrical component. Each layer of segmented mold is provided with a conical hole (11). The conical hole (11) is used to fit the extruded part. Each layer of segmented mold is provided with an independently controllable electric heating wire (13); wherein, each layer of segmented mold is composed of 3-4 segmented bodies, and the outer wall of each layer of segmented mold is an arc surface adapted to the inner cavity of the cylindrical blank; Step 3: Only control the heating of the first layer of segmented mold (1), heat it to the set temperature and keep the temperature constant, then control the extrusion part (21) of the first layer of segmented mold (1) to move axially downward, so as to realize the radial outward movement of the segmented body of the first layer of segmented mold (1), and at the same time control the rotating platform to rotate at the preset speed. After the extrusion is in place, the top pressure rod is removed and the corresponding heating system is turned off. Step 4: Only control the heating of the third layer segmented mold (3). After heating to the set temperature, keep the temperature constant, fix the first layer segmented mold (1), and then control the extrusion part three (23) of the third layer segmented mold (3) to move axially downward, so as to realize the radial outward movement of the segmented body of the third layer segmented mold (3). At the same time, control the rotating platform to rotate at the preset speed. After extrusion is in place, remove the top pressure rod and the extrusion part three (23) and turn off the corresponding heating system. Step 5: Only control the heating of the second layer segmented mold (2), heat it to the set temperature and keep the temperature constant, fix the third layer segmented mold (3), and then control the extrusion part (22) of the second layer segmented mold (2) to move axially downward, so as to realize the radial outward movement of the segmented body of the second layer segmented mold (2). At the same time, control the rotating platform to rotate at the preset speed. After the extrusion is in place, the top pressure rod is removed and the corresponding heating system is turned off. Step 6: Exit each layer of the segmented mold.

2. The forming process for the internal ribs of the thin-walled lightweight alloy cylindrical component according to claim 1, characterized in that: The rotational speed of the rotating platform is 8000-10000 r / min.

3. The forming process for the internal ribs of the thin-walled lightweight alloy cylindrical component according to claim 2, characterized in that: The cross-section of the annular mold cavity (10) is rectangular, and the depth and height of the annular mold cavity (10) are both no more than 10 mm.

4. The forming process for the internal ribs of a thin-walled lightweight alloy cylindrical component according to any one of claims 1-3, characterized in that, It also includes a fourth layer of segmented mold (4) and a fifth layer of segmented mold (5) arranged sequentially from bottom to top, with the fourth layer of segmented mold (4) located above the third layer of segmented mold (3); it also includes: Step 51: Only control the heating of the fourth layer segmented mold (4), heat it to the set temperature and keep the temperature constant, fix the third layer segmented mold (3), and then control the extrusion part (24) of the fourth layer segmented mold (4) to move axially downward, so as to realize the radial outward movement of the segmented body of the fourth layer segmented mold (4), and at the same time control the rotating platform to rotate at the preset speed. After the extrusion is in place, the top pressure rod is removed and the corresponding heating system is turned off. Step 52: Only control the heating of the fifth layer segmented mold (5). After heating to the set temperature, keep the temperature constant, fix the fourth layer segmented mold (4), and then control the extrusion part (25) of the fifth layer segmented mold (5) to move axially downward, so as to realize the radial outward movement of the segmented body of the fifth layer segmented mold (5). At the same time, control the rotating platform to rotate at the preset speed. After the extrusion is in place, the top pressure rod is removed and the corresponding heating system is turned off.

5. The forming process for the internal ribs of the thin-walled lightweight alloy cylindrical component according to claim 4, characterized in that: The thin-walled lightweight alloy cylindrical component is an aluminum alloy cylindrical component with a wall thickness of no more than 5 mm.

6. The forming process for the internal ribs of the thin-walled lightweight alloy cylindrical component according to claim 5, characterized in that: The downward axial movement speed of each extruded component is 0.5-1 mm / s.

7. The forming process for the internal ribs of the thin-walled lightweight alloy cylindrical component according to claim 6, characterized in that: In each step, the rotating platform rotates repeatedly in a pattern of "clockwise rotation for 5-8 seconds - counterclockwise rotation for 5-8 seconds".

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