Process for progressive forming of inner rib thin-walled cylinder by active power rotary roll forming

Abstract

The inner and outer ribs thin-walled cylinder inside and outside the wheel active strong power roll forming process, using the inner and outer roll wheel along the cylindrical blank circumference symmetry uniform distribution, the outer roll wheel roll after the current pass along the axial downward movement to complete the next pass processing of the cylindrical blank, until along the axial movement to the inner roll bottom end, the inner and outer roll wheel along the axial downward movement and repeat the above processing, until the completion of the processing of the cylindrical blank; In the roll forming process, the cylindrical blank is hardened, the performance is improved, and there is no drum-shaped fold caused by the axial stress in the axial feeding process and the inner side reinforcing rib is not broken; To different size of cylindrical blank and different size, shape of the inner side reinforcing rib, without preparing different core mold, only change the different inner roll, high flexibility of processing, low cost; The formed part has the advantages of high surface quality, good material performance, high near net shape material utilization.

Description

Technical Field

[0001] This invention relates to the field of forming technology for thin-walled cylindrical parts with internal ribs, specifically to a segmented progressive forming process for internally ribbed thin-walled cylindrical parts with active high-pressure spinning and rolling of inner and outer rollers. Background Technology

[0002] Ultra-large diameter (several meters or even tens of meters in diameter) internally reinforced thin-walled cylindrical components are widely used in aircraft shells, pressure vessel shells, submarine hulls, aerospace rocket engine fuel tanks and engine shells, etc. The main purpose of the internal reinforcing ribs is to improve the strength of thin-walled rotating parts. Complex operating conditions often require internally reinforced thin-walled rotating parts to have high strength and low weight.

[0003] Currently, large-diameter cylindrical parts with internal ribs are typically processed using two methods: welding and spin forming with a mandrel. Welding (Zeng Xiang, Fan Xiaoguang, Li Hongwei, Zhan Mei, Gao Pengfei, Chen Qi. Research progress on spin forming of complex thin-walled parts with internal ribs [J]. Precision Forming Engineering, 2019, 11(05): 21-31.) involves rolling sheet metal and then welding it into a cylindrical part to obtain a cylindrical part with internal ribs. This method is simple and efficient. However, when forming cylindrical parts using this method, numerous bent small plates are welded together, resulting in a large number of welds. An axial weld reduces the strength of the cylinder by 1 / 2, and a tangential weld reduces the strength by 1 / 3. To ensure the required strength, the thickness of the sheet metal must be increased, which leads to an increase in weight. As a result, the weight of the rocket engine cylinder with the welded structure is significantly higher than that of the cylinder formed by the new wheel-rolling process for ultra-large diameter thin-walled cylindrical parts with internal ribs.

[0004] Spinning with an integral core mold and internal rib groove (Zeng Xiang, Fan Xiaoguang, Li Hongwei, Zhan Mei, Gao Pengfei, Chen Qi. Research progress on spin forming of complex thin-walled parts with internal ribs [J]. Precision Forming Engineering, 2019, 11(05): 21-31.) has the following problems: the core mold diameter is too large, which increases the cost of strong spin forming with a core mold by half; the core mold surface has internal rib grooves, and the external spinning wheel strongly spins the cylindrical workpiece blank into the groove. Because the external spinning wheel causes the blank to be subjected to huge axial stress, the inner reinforcing ribs of the cylindrical blank are pulled off or cracked, thus causing the spinning process to fail and produce defective products.

[0005] In summary, the current cutting, welding, and integral mandrel spinning methods for thin-walled cylindrical bodies with internal ribs have the following shortcomings: cutting and welding processes have low production efficiency and produce a large number of welds, which weaken the strength of the cylindrical body and increase the overall weight of the workpiece; the integral mandrel spinning process results in high mandrel manufacturing costs, and the internal ribs may be torn or broken during the spinning process, resulting in defective products.

[0006] Therefore, traditional methods for machining large-diameter cylindrical parts with internal ribs can no longer meet the requirements for changing wall thickness, high efficiency, high performance, high precision, and lightweighting. Thus, there is an urgent need for a new manufacturing process capable of integrally forming large-diameter cylindrical parts with internal ribs. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide a segmented progressive forming process for internally reinforced thin-walled cylinders with active high-pressure spinning and rolling, which combines the principles of high-pressure spinning and rolling. During the spinning process, for workpieces of different sizes and different shapes of internal reinforcing ribs, it is not necessary to add mandrels of different sizes, thus saving a lot of costs. At the same time, since there is no axial stress caused by axial feed during the processing, axial bulging wrinkles are less likely to occur. It has the advantages of easy adjustment of forming diameter, small forming load, high precision, low residual stress in the workpiece, and high material utilization.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A segmented progressive forming process for internally reinforced thin-walled cylinders with active high-pressure spin rolling between inner and outer rollers includes the following steps:

[0010] The first step is to clamp the cylindrical blank 5 onto the fixture 6 of the spinning mill, and fix the cylindrical blank 5 onto the fixture 6 with pins 7; the fixture 6 is connected to the spindle 8 of the spinning mill.

[0011] The second step is to start the spindle 8 of the spinning equipment. The spindle 8 drives the cylindrical blank 5 to rotate through the clamp 6. The outer spinning wheel 3 starts to feed radially from the outermost ring of the cylindrical blank 5. At the same time, the servo motor 1 drives the outer spinning wheel 3 to rotate actively through the planetary reducer 2, which is conducive to the radial thinning of the cylindrical blank 5 and the formation of the inner reinforcing ribs. The servo motor 1 and the planetary reducer 2 control the linear speed of the rotation of the outer side of the outer spinning wheel 3 and the inner side of the cylindrical blank 5 to be the same, so as to ensure that the inner reinforcing ribs of the cylindrical blank 5 are formed completely and continuously.

[0012] Third step, the outer rotating wheel 3 feeds in the opposite radial direction, away from the cylindrical blank 5; the downward axial movement distance of the outer rotating wheel 3 is less than the middle working area of ​​the outer rotating wheel 3;

[0013] In the fourth step, the outer rotating wheel 3 continues to perform radial feed according to the first to third steps to complete the second pass of thinning and inner reinforcing rib forming work;

[0014] Fifth step: When the outer rotating wheel 3 is fed axially to near the bottom of the inner rotating wheel 4, the inner rotating wheel 4 is fed axially downward. The downward axial movement distance of the inner rotating wheel 4 is less than the height of the inner rotating wheel 4.

[0015] Step 6: Repeat steps 1 to 6 above until the forming of the inner reinforcing ribs of the cylindrical blank 4 is completed.

[0016] Step 7: After completing the thinning and inner reinforcing rib forming work, remove the outer spinning wheel 3 and inner spinning wheel 4, stop the main shaft 8 and servo motor 1 of the rolling mill, and take out the cylindrical blank 5.

[0017] During the high-pressure spinning forming process of the cylindrical blank 5 by the outer spinning wheel 3, the radial feed speed of the outer spinning wheel 3 and the rotation speed of the inner spinning wheel 4 and the spindle 8 of the spinning equipment are controlled so that the linear speed of the inner spinning wheel 4 at the tangent point of the cylindrical blank 5 is consistent, so as to obtain the cylindrical blank 5 with the desired diameter, wall thickness and inner reinforcing ribs.

[0018] The outer rotating wheel 3 and the inner rotating wheel 4 are connected to the output shaft of the planetary reducer 2 via a transmission shaft. The input shaft of the planetary reducer 2 is connected to the servo motor 1. The speed of the servo motor 1 is adjustable, so that the linear speed of the cylindrical blank 5 rotating at the point where it is tangent to the inner rotating wheel 4 is the same.

[0019] The cylindrical blank 5 is fixed to the fixture 6 by circumferentially distributed pins 7.

[0020] The aforementioned rotary rolling process employs four outer rotary wheels 3 and inner rotary wheels 4 evenly and symmetrically distributed along the circumference of the cylindrical blank 5, while simultaneously processing the cylindrical blank 5 along its inner and outer surfaces.

[0021] The central working area of ​​the outer rotating wheel 3 is a cylindrical end face area, which is used to complete the rolling work of gradually thinning the cylinder wall. The upper and lower parts of the cylindrical working area are inclined surface areas, which are connected by rounded corners.

[0022] The height of the inner rotating wheel 4 is more than five times greater than the height of the outer rotating wheel 3.

[0023] In summary, compared with existing technologies, this invention combines the principle of mandrel spinning, but not a single mandrel; instead, it uses multiple mandrels. It integrates the principle of high-pressure spinning with rollers and the principle of sheet metal rolling to achieve efficient and high-performance forming of large-diameter or ultra-large-diameter thin-walled cylindrical parts with internal ribs. Therefore, this invention has the following advantages:

[0024] In the present invention, during the active and powerful spinning of the rollers, the outer spinning roller 3 rotates actively, and there is no need for the torque to be transmitted entirely by the cylindrical blank 5 and the fixture 6, thereby reducing the torque generated during the processing and forming process, and thus reducing the twisting and instability of the cylindrical blank 5.

[0025] In the active high-pressure spinning process of the present invention, when the outer spinning wheel 3 contacts the cylindrical blank 5, it only performs radial feed and there is no large axial stress caused by axial feed. This greatly solves the problem of drum-shaped wrinkles generated during spinning and the situation where the inner reinforcing ribs are pulled apart due to axial stress during the forming process, thus improving the forming quality of the thin-walled cylindrical body with inner ribs.

[0026] The height of the inner rotating wheel 4 in this invention is more than five times greater than the height of the outer rotating wheel 3. This is because the inner rotating wheel 4 only moves axially and not radially. Therefore, increasing its axial length reduces the number of axial movements, thus simplifying the forming process.

[0027] In the process of strong active spinning forming of the present invention, there are no spiral marks between passes caused by axial feed in the spinning forming process of the present invention, which can effectively improve the surface forming accuracy of the cylindrical blank 5. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the initial layout for the inner ribbed thin-walled cylinder forming by rotary rolling according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the first radial feed process of the inner ribbed thin-walled cylinder forming by rotary rolling in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the first pass of the outer rotating wheel removal process in the inner ribbed thin-walled cylinder forming process according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the second radial feed process of the inner ribbed thin-walled cylinder forming by rotary rolling in an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of the axial feeding process of the inner rotating wheel in the inner ribbed thin-walled cylinder forming process according to an embodiment of the present invention.

[0033] Figure 6 This is a schematic diagram of the process of the inner and outer rotating wheels retracting during the forming of the thin-walled cylindrical body with internal ribs according to an embodiment of the present invention.

[0034] Figure 7 This is a top view of the cross-sectional profile of the thin-walled cylindrical body with internal ribs formed by rotary rolling according to an embodiment of the present invention.

[0035] Figure 8 This is a comparison diagram of the external spinning wheel structure of the present invention and the traditional spinning wheel structure. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0037] Reference Figures 1-7A segmented progressive forming process for internally reinforced thin-walled cylindrical blanks using active high-pressure rotary rolling with inner and outer rollers, employing four outer rotary rollers 3 and inner rotary rollers 4 symmetrically and evenly distributed along the circumference of the cylindrical blank 5. Simultaneously, the inner and outer surfaces of the cylindrical blank 5 are processed. The thinning of the cylindrical blank 5 and the formation of the inner reinforcing ribs are achieved by shifting the working range downwards with each rotation. The process includes the following steps:

[0038] The first step is to clamp the cylindrical blank 5 onto the fixture 6 of the spinning equipment and fix the cylindrical blank 5 onto the fixture 6 with pins 7. In this embodiment, the cylindrical blank 5 is fixed onto the fixture 6 by pins 7 distributed around the circumference to prevent relative sliding between the cylindrical blank 5 and the fixture 6 when it rotates, as well as other movements that may cause instability during the spinning process.

[0039] The fixture 6 is connected to the spindle 8 of the spinning equipment, and the spindle 8 provides power to drive the fixture 6 and the cylindrical billet 5 to perform circumferential motion.

[0040] The second step is to start the spindle 8 of the spinning equipment. The spindle 8 drives the cylindrical blank 5 to rotate through the clamp 6. The outer spinning wheel 3 starts to feed radially from the outermost ring of the cylindrical blank 5. At the same time, the servo motor 1 drives the outer spinning wheel 3 to rotate actively through the planetary reducer 2, which is conducive to the radial thinning of the cylindrical blank 5 and the formation of the inner reinforcing ribs. The servo motor 1 and the planetary reducer 2 control the linear speed of the rotation of the outer side of the outer spinning wheel 3 and the inner side of the cylindrical blank 5 to be the same, so as to ensure that the inner reinforcing ribs of the cylindrical blank 5 are formed completely and continuously.

[0041] The outer rotating wheel 3 and the inner rotating wheel 4 are connected to the output shaft of the planetary reducer 2 via a transmission shaft. The input shaft of the planetary reducer 2 is connected to the servo motor 1. The speed of the servo motor 1 is adjustable, so that the linear speed of the cylindrical blank 5 at the point where it is tangent to the inner rotating wheel 4 is the same.

[0042] The third step is to feed the outer rotating wheel 3 in the opposite radial direction, away from the cylindrical blank 5. In order to ensure that there is an overlap between the two working zones, the downward axial movement distance of the outer rotating wheel 3 is less than the middle working area of ​​the outer rotating wheel 3.

[0043] In the fourth step, the outer rotating wheel 3 continues to perform radial feed according to the first to third steps to complete the second pass of thinning and inner reinforcing rib forming work;

[0044] Fifth step: When the outer rotating wheel 3 is fed axially to near the bottom of the inner rotating wheel 4, the inner rotating wheel 4 is fed axially downward. In order to ensure the continuity of the forming work, the downward axial movement distance of the inner rotating wheel 4 is less than the height of the inner rotating wheel 4.

[0045] Step 6: Repeat steps 1 to 6 above until the forming of the inner reinforcing ribs of the cylindrical blank 4 is completed.

[0046] Step 7: After completing the thinning and inner reinforcing rib forming work, remove the outer spinning wheel 3 and inner spinning wheel 4, stop the main shaft 8 and servo motor 1 of the rolling mill, and take out the cylindrical blank 5.

[0047] During the high-pressure spinning forming process of the cylindrical blank 5 by the outer spinning wheel 3, the radial feed speed of the outer spinning wheel 3 and the rotation speed of the inner spinning wheel 4 and the spindle 8 of the spinning equipment are controlled so that the linear speed of the inner spinning wheel 4 at the tangent point of the cylindrical blank 5 is consistent, so as to obtain the cylindrical blank 5 with the desired diameter, wall thickness and inner reinforcing ribs.

[0048] Reference Figure 8 The outer spinning wheel 3 differs from the traditional spinning wheel 9. The traditional spinning wheel 9 has a spinning ridge in the middle, which produces spiral marks during spinning. The middle working area of ​​the outer spinning wheel 3 is a cylindrical end face area, which is used to complete the rolling work of gradually thinning the cylinder wall. The upper and lower sides of the cylinder are inclined surface areas, and the inclined surface areas are connected to the working area by rounded corners, which is conducive to the outer spinning wheel 3 biting into the cylindrical blank 5 at the beginning of spinning and facilitates the material to flow to the upper and lower sides during spinning.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention are all within the scope of protection of the present invention.

Claims

1. A segmented progressive forming process for an inner-ribbed thin-walled cylinder with active high-pressure spinning of inner and outer rollers, characterized in that, Includes the following steps: The first step is to clamp the cylindrical blank (5) on the jig (6) of the spinning equipment and fix the cylindrical blank (5) on the jig (6) by means of pins (7); the jig (6) is connected to the spindle (8) of the spinning equipment. The second step is to start the spindle (8) of the spinning equipment. The spindle (8) drives the cylindrical blank (5) to rotate through the clamp (6). The outer spinning wheel (3) starts to feed radially from the outermost ring of the cylindrical blank (5). At the same time, the servo motor (1) drives the outer spinning wheel (3) to rotate actively through the planetary reducer (2), which is conducive to the radial thinning of the cylindrical blank (5) and the formation of the inner reinforcing ribs. The servo motor (1) and the planetary reducer (2) control the linear speed of the rotation of the outer side of the outer spinning wheel (3) to be the same as that of the cylindrical blank (5), so as to ensure that the inner reinforcing ribs of the cylindrical blank (5) are formed completely and continuously. In the third step, the outer rotating wheel (3) feeds in the opposite radial direction, away from the cylindrical blank (5); the downward axial movement distance of the outer rotating wheel (3) is less than the middle working area of ​​the outer rotating wheel (3); In the fourth step, the outer rotating wheel (3) continues to feed radially according to the first to third steps to complete the second pass of thinning and inner reinforcing rib forming work; Fifth step, when the outer rotating wheel (3) is fed axially to near the bottom of the inner rotating wheel (4), the inner rotating wheel (4) is fed axially downward, and the downward axial movement distance of the inner rotating wheel (4) is less than the height of the inner rotating wheel (4); Step 6: Repeat steps 1 to 5 above until the forming of the inner reinforcing ribs of the cylindrical blank (4) is completed; Step 7: After completing the thinning and inner reinforcing rib forming work, remove the outer spinning wheel (3) and inner spinning wheel (4), stop the main shaft (8) and servo motor (1) of the rolling mill, and take out the cylindrical blank (5). During the process of high-pressure spinning forming of cylindrical blank (5) by the outer spinning wheel (3), the radial feed speed of the outer spinning wheel (3) and the rotation speed of the inner spinning wheel (4) and the spindle (8) of the spinning equipment are controlled so that the linear speed of the inner spinning wheel (4) at the tangent point to the cylindrical blank (5) is consistent, and the desired diameter, wall thickness and inner reinforcing ribs of the cylindrical blank (5) are obtained. The outer rotating wheel (3) and the inner rotating wheel (4) are connected to the output shaft of the planetary reducer (2) via a transmission shaft. The input shaft of the planetary reducer (2) is connected to the servo motor (1). The speed of the servo motor (1) is adjustable, so that the linear speed of the cylindrical blank (5) rotating at the tangent point to the inner rotating wheel (4) is the same. The middle working area of ​​the outer rotating wheel (3) is a cylindrical end face area, which is used to complete the rolling work of gradually thinning the cylinder wall. The upper and lower sides of the cylindrical end face area are inclined surface areas, and the inclined surface area and the cylindrical end face area are connected by rounded corners.

2. The process according to claim 1, characterized in that: The cylindrical blank (5) is fixed on the fixture (6) by circumferentially distributed pins (7).

3. The process according to claim 1, characterized in that: The aforementioned rotary rolling process employs four external rotary wheels (3) and internal rotary wheels (4) evenly and symmetrically distributed along the circumference of the cylindrical blank (5), while simultaneously processing the cylindrical blank (5) along its inner and outer surfaces.

4. The process according to claim 1, characterized in that: The height of the inner rotating wheel (4) is more than five times the height of the outer rotating wheel (3).

Images