Progressive forming process of super-large diameter thin-walled rotary body by wheel-driven power roll forming

Abstract

A kind of large-diameter thin-walled rotary body's wheel driving force rolling type progressive forming process, wheel rolling adopts that rolling wheel is uniformly distributed along the circumferential symmetry of cylindrical blank, and the inner and outer surfaces of cylindrical blank are processed, and the thinning processing of cylindrical blank is completed by the downward movement of each circle working range;In the process of wheel rolling, the cylindrical blank is hardened and thinned, the performance is improved, and there is no drum-shaped fold caused by axial compression stress in the process of axial feeding;For different sizes of cylindrical blank, different core molds are not needed, and the processing flexibility is high, and the cost is low;The formed piece has the advantages of high surface quality, good material performance and high near-net forming material utilization.

Description

Technical Field

[0001] This invention belongs to the field of processing technology for ultra-large diameter thin-walled rotating parts made by plastic forming of metal materials, specifically involving an active high-power rotary rolling progressive forming process for ultra-large diameter thin-walled rotating parts. Background Technology

[0002] Ultra-large diameter (several meters or even tens of meters in diameter) thin-walled rotating parts are widely used in aircraft cylinders, pressure vessel shells, submarine rotating shells, fuel tanks and engine shells in aerospace rocket engines, etc. Complex usage conditions often require thin-walled cylindrical parts to have high strength and low weight.

[0003] Currently, common manufacturing methods involve using sheet metal as raw material, manufacturing in sections using traditional processes, and then welding; or using sheet metal to roll into a circle and connecting the joints using stir welding or other welding methods. Therefore, these welds often contain longitudinal welds or one or more circumferential welds. Due to varying degrees of defects at the weld joints, the parts are heavy, have poor load-bearing capacity, and low production efficiency. Furthermore, the localized thermal deformation caused by welding severely affects the dimensional accuracy and surface quality of the workpiece. When using traditional mandrel-based high-pressure spinning to process such ultra-large diameter thin-walled cylindrical parts, a large mandrel needs to be manufactured. Simultaneously, the torque required during the rotation of the cylindrical part driven by the mandrel is significant, making the manufacturing and design of related equipment difficult. Therefore, the process has certain limitations and cannot meet engineering requirements. Sheet metal welding, sheet metal roll welding, and mandrel-based high-pressure spinning are either limited by process characteristics or equipment scale, and thus are not suitable for the efficient, high-performance, and low-cost manufacturing of ultra-large diameter thin-walled rotating parts.

[0004] Currently, the simple force spinning of the wheel is widely used in the metal shell of aerospace rocket engines. For example, the Chinese patent method for spinning the wheel of rolled and welded cylindrical parts (publication number CN 103736807A) first rolls and welds the cylindrical part of the sheet blank, then processes the reinforcing ring, and finally performs multiple passes of wheel spinning. Such processing methods still have the following shortcomings: (1) When the wheel is passively and forcefully spun, the wheel does not have an active force. The rotating workpiece is transmitted torque by the turntable. The transmission distance is long, and the wall thickness of the cylindrical part is thin, which will generate a large torque and axial compressive stress. The wall thickness reduction rate of the cylinder is large, so it is easy to cause the cylinder to twist and become unstable; (2) When the wheel is actively and forcefully spun, the axial compressive stress on the cylinder during the spinning process is large due to the large wall thickness reduction rate, which will produce axial drum-shaped wrinkles; (3) The surface of the workpiece after simple wheel spinning has spiral marks between passes, resulting in low surface accuracy of the workpiece. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a rotary rolling process for ultra-large diameter thin-walled rotating bodies. Combining the principles of rotary rolling and rotary pressing, the process eliminates the need for additional mandrels of different sizes to process parts of different dimensions, thus saving costs. At the same time, since there is no axial compressive stress caused by axial feed during the processing, axial bulging wrinkles are less likely to occur. This process has advantages such as low cost, high dimensional accuracy, near-net-shape forming, and reduced material waste.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A progressive forming process for an ultra-large diameter thin-walled rotating body using a rotary active high-pressure spinning method includes the following steps:

[0008] The first step is to clamp the cylindrical blank 4 onto the internal expansion fixture 6 of the rotary rolling equipment and fix the cylindrical blank 4 onto the internal expansion fixture 6 with pins 5; the internal expansion fixture 6 is connected to the main shaft 7 of the rotary rolling equipment.

[0009] The second step is to start the spindle 7 of the spinning equipment. The spindle 7 drives the cylindrical billet 4 to rotate through the internal expansion clamp 6. The inner and outer wheels of the spinning roller 3 start to feed radially from the outermost ring of the cylindrical billet 4. At the same time, the servo motor 1 drives the spinning roller 3 to rotate actively through the planetary gear reducer 2, which is conducive to the radial thinning of the cylindrical billet 4 until the predetermined thinning rate of this pass is reached.

[0010] The third step is to feed the spinning wheel 3 in the opposite radial direction, away from the cylindrical blank 4. In order to ensure that there is an overlap between the two working areas, the downward axial movement distance of the spinning wheel 3 is less than that of the middle working area of ​​the spinning wheel 3.

[0011] In the fourth step, the spinning roller 3 continues to feed radially in accordance with the first to third steps to complete the second round of thinning work;

[0012] Fifth step: After completing the thinning and forming work, remove the spinning roller 3, stop the spinning equipment spindle 7 and servo motor 1, and take out the cylindrical blank 4.

[0013] During the process of high-intensity rotary rolling of cylindrical blank 4 by the rotary rolling wheel 3, the desired diameter and wall thickness of cylindrical blank 4 can be obtained by controlling the radial feed speed of the rotary rolling wheel 3.

[0014] The rolling mill 3 is connected to the output shaft of the planetary gear reducer 2 via a transmission shaft. The input shaft of the planetary gear 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 4 is consistent with the linear speed of the rolling mill 3.

[0015] The cylindrical blank 4 is fixed to the internal expansion clamp 6 by circumferentially distributed pins 5.

[0016] The aforementioned rotary rolling process employs four pairs of rotary rolling wheels 3 evenly and symmetrically distributed along the circumference of the cylindrical blank 4, simultaneously processing the inner and outer surfaces of the cylindrical blank 4.

[0017] The central working area of ​​the rolling mill 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.

[0018] Compared to existing technologies, this invention combines the principles of high-pressure spinning and rolling to achieve thinning and forming of large-size cylindrical parts, offering the following advantages:

[0019] (1) In the present invention, when the roller is actively rotating, the roller 3 rotates actively, and there is no need for the torque to be transmitted completely by the cylindrical blank 4 and the internal expansion clamp 6, thereby reducing the torque generated during the processing and reducing the twisting and instability of the cylindrical blank 4.

[0020] (2) In the present invention, when the spinning wheel 3 contacts the cylindrical blank 4, it only performs radial feeding and there is no situation where the axial feeding brings large axial compressive stress. This can greatly solve the problem of drum-shaped wrinkles generated during the spinning process and improve the production quality of thin-walled cylindrical parts.

[0021] (3) In the process of strong active spinning of the roller, the present invention does not have the spiral marks between passes caused by axial feed during the simple spinning process of the roller, which can effectively improve the surface accuracy of the cylindrical blank 4. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the initial layout for rotary rolling forming according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the radial feed process for rotary rolling forming according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the radial feed process for rotary rolling forming according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the radial feed process of rotary rolling forming according to an embodiment of the present invention.

[0026] Figure 5 This is a schematic diagram of radial retraction during rotary rolling forming according to an embodiment of the present invention.

[0027] Figure 6 This is a top view of the cross-sectional shape of the rotary rolling forming according to an embodiment of the present invention.

[0028] Figure 7This is a comparison diagram of the spinning wheel structure of this invention and the traditional spinning wheel structure. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0030] Reference Figures 1-6 A rotary rolling process for forming ultra-large diameter thin-walled rotating bodies using a pair of active, high-power rotary rolling method involves four pairs of rolling wheels 3 symmetrically and evenly distributed around the circumference of a cylindrical blank 4, simultaneously processing the inner and outer surfaces of the cylindrical blank 4. Thinning of the cylindrical blank 4 is achieved by shifting the working range downwards with each revolution. The process includes the following steps:

[0031] The first step is to clamp the cylindrical blank 4 onto the inner expansion fixture 6 of the spinning equipment and fix the cylindrical blank 4 onto the inner expansion fixture 6 with pins 5. In this embodiment, the cylindrical blank 4 is fixed onto the inner expansion fixture 6 by pins 5 symmetrically distributed around the circumference to prevent relative sliding between the cylindrical blank 4 and the inner expansion fixture 6 when rotating, as well as other movements that may cause instability in the spinning process.

[0032] The internal expansion clamp 6 is connected to the spindle 7 of the spinning equipment. The spindle 7 provides power to drive the internal expansion clamp 6 and the cylindrical billet 4 to perform circumferential motion.

[0033] The second step is to start the spindle 7 of the spinning equipment. The spindle 7 drives the cylindrical billet 4 to rotate through the internal expansion clamp 6. The inner and outer wheels of the spinning roller 3 start to feed radially from the outermost ring of the cylindrical billet 4. At the same time, the servo motor 1 drives the spinning roller 3 to rotate actively through the planetary gear reducer 2, which is conducive to the radial thinning of the cylindrical billet 4 until the predetermined thinning rate of this pass is reached.

[0034] The rolling mill 3 is connected to the output shaft of the planetary gear reducer 2 via a transmission shaft. The input shaft of the planetary gear reducer 2 is connected to the servo motor 1. The speed of the servo motor 1 is adjustable, so that the linear velocity of the cylindrical blank 4 is consistent with the linear velocity of the rolling mill 3.

[0035] The third step is to feed the spinning wheel 3 in the opposite radial direction, away from the cylindrical blank 4. In order to ensure that there is an overlap between the two working areas, the downward axial movement distance of the spinning wheel 3 is less than that of the middle working area of ​​the spinning wheel 3.

[0036] In the fourth step, the spinning roller 3 continues to feed radially in accordance with the first to third steps to complete the second round of thinning work;

[0037] Fifth step: After completing the thinning and forming work, remove the spinning roller 3, stop the spinning equipment spindle 7 and servo motor 1, and take out the cylindrical blank 4.

[0038] During the process of high-intensity rotary rolling of cylindrical blank 4 by the rotary rolling wheel 3, the desired diameter and wall thickness of cylindrical blank 4 can be obtained by controlling the radial feed speed of the rotary rolling wheel 3.

[0039] Reference Figure 7 The aforementioned spinning wheel 3 differs from the traditional spinning wheel 8. The traditional spinning wheel 8 has a spinning ridge in the middle, which produces spiral marks during spinning. The working area in the middle of the 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 beneficial for the spinning wheel 3 to bite into the cylindrical blank 4 at the beginning of spinning.

[0040] 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 process for the incremental forming of a super-large diameter thin-walled revolution body by means of a wheel-driven power roll forming with counter-rollers, characterized in that, It comprises the following steps: First, the cylindrical blank (4) is clamped on the inner expanding clamp (6) of the rotary rolling equipment, and the cylindrical blank (4) is fixed on the inner expanding clamp (6) through the pin (5); the inner expanding clamp (6) is connected with the main shaft (7) of the rotary rolling equipment; Second, start the main shaft (7) of the rotary rolling equipment, and the cylindrical blank (4) is driven to rotate by the inner expanding clamp (6), and the inner and outer wheels of the rotary rolling wheel (3) start radial feeding from the outermost end of the cylindrical blank (4), while the servo motor (1) drives the rotary rolling wheel (3) to rotate through the planetary gear reducer (2), which is beneficial to the radial thinning of the cylindrical blank (4), until the predetermined thinning rate of the pass is reached; Third, the rotary rolling wheel (3) feeds in the opposite direction, away from the cylindrical blank (4), to ensure that there is an overlapping part between the two working areas, and the rotary rolling wheel (3) moves axially downward by a distance less than the middle working area of the rotary rolling wheel (3); Fourth, the rotary rolling wheel (3) continues to feed radially according to the first to third steps to complete the thinning work of the second circle; Fifth, after completing the thinning and forming work, the rotary rolling wheel (3) is removed, the main shaft (7) of the rotary rolling equipment and the servo motor (1) are stopped, and the cylindrical blank (4) is taken out; During the processing of the rotary rolling wheel (3) on the cylindrical blank (4), the radial feeding speed of the rotary rolling wheel (3) is controlled to obtain the cylindrical blank (4) with the desired diameter and wall thickness; The rotary rolling wheel (3) is connected with the output shaft of the planetary gear reducer (2) through the transmission shaft, the input shaft of the planetary gear reducer (2) is connected with the servo motor (1), and the rotational speed of the servo motor (1) can be adjusted, so that the linear speed of the cylindrical blank (4) and the linear speed of the rotary rolling wheel (3) are consistent; The middle working area of the rotary rolling wheel (3) is a cylindrical end face area, which is used to complete the rolling work of gradually thinning the cylinder wall, and the upper and lower sides of the cylinder are inclined surface areas, which are connected with the working area through a round corner.

2. The process of claim 1, wherein: The cylindrical blank (4) is fixed on the inner expanding clamp (6) by the circumferentially symmetric distributed pins (5).

3. The process of claim 1, wherein: The four pairs of rotary rolling wheels (3) are uniformly and symmetrically distributed along the circumference of the cylindrical blank (4), and simultaneously process the cylindrical blank (4) along the inner and outer surfaces.

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