Novel motor rotor sheath winding system

Abstract

The invention discloses a novel motor rotor sheath winding system, which belongs to the technical field of motor rotor winding forming process, and comprises a prepreg tape wire releasing device, a driving rewinding device, a tension control device, a film wire releasing device, a motor rotor winding platform, a loading and unloading manipulator and a curing oven, the problems that an existing winding device is complex, poor in adaptability, not matched with a winding process, high in resin waste rate, low in fiber tension and the like are solved, and efficient and environment-friendly large-tension precise winding is synchronously achieved. The guide wheel is made of a non-stick material, so that the risk of friction fluffing of the prepreg tape is reduced, the width of the prepreg tape is stable through the folding and unwinding control structure, and the prepreg tape can be constantly wound on a motor rotor at a high speed and with ultrahigh tension through the driving rewinding structure and the tension control structure.

Description

Technical Field

[0001] The invention relates to the technical field of motor rotor winding forming technology, and more specifically to a novel motor rotor sheath winding system. Background Art

[0002] Winding is a process used to manufacture fiber-reinforced composite materials, usually used to produce cylindrical structural parts. The core of the winding process is to wind the fiber material on the mold according to a specific pattern to form composite parts, such as motor winding rotors, pressure cylinders, composite pipes, etc., which are widely used in aerospace, automotive industry, sports equipment, wind power generation and new energy fields.

[0003] For motor rotors, the traditional manufacturing process is to separately wind, dry, demold, and process the carbon fiber sheath on the outer surface into parts. Then, the formed carbon fiber sheath is put on the motor rotor. This method has a series of reasons, such as the complex production process of the carbon fiber sheath, serious pollution, high precision required for the assembly of the formed sheath and the motor rotor, and great damage to the carbon fiber sheath during installation. It not only brings high costs but also leads to low strength of the motor rotor sheath after production. For motor rotors, a new manufacturing process is to directly wind the carbon fiber on the electronic rotor to form a motor rotor carbon fiber sheath.

[0004] The prior art is a wet winding process, in which the fiber is released through a creel, enters an impregnation device, and then is wound on a motor rotor, and finally heated and cured. Although the existing method has largely solved the problems of high installation accuracy of the sheath and the motor rotor in the traditional process, the fiber is easy to bring out the resin after entering the impregnation device, resulting in resin waste. Therefore, the winding speed is generally low. At the same time, the solvent or low-boiling point component in the resin system is easy to form defects such as bubbles and gaps during curing, affecting the molding quality and the performance of the final product. In addition, it also has an adverse effect on personnel health, equipment maintenance and environmental protection. In the existing winding process, since the resin content of the product is difficult to control and inspect during the winding process, the tension applied to the fiber is also difficult to control. Since the motor rotor sheath requires high strength, this method is not easy to achieve the tension value required for the production of the motor rotor. In order to solve the shortcomings of traditional processes and existing processes, the present invention designs a winding method for a new sheath motor rotor. Summary of the invention

[0005] Technical issues to be solved In view of the problems existing in the prior art, the purpose of the present invention is to provide a new motor rotor sheath winding system. The present invention solves the problems of the existing winding device being complex, poorly adaptable, not matching the winding process, high resin waste rate, and low fiber tension, and simultaneously realizes high-efficiency and environmentally friendly high-tension precision winding. By adopting a guide wheel made of non-stick material, the risk of friction and fuzzing of the prepreg tape is reduced. By using the folding wire release control structure, the width of the prepreg tape is stabilized. By driving the rewinding structure and the tension control structure, the prepreg tape can be wound onto the motor rotor at high speed and with constant ultra-high tension.

[0006] Technical Solution To solve the above problems, the present invention adopts the following technical solutions: A novel motor rotor sheath winding system comprises a prepreg wire unwinding device, a drive rewinding device, a tension control device, a film wire unwinding device, a motor rotor winding platform, a loading and unloading manipulator and a curing oven, wherein an aluminum alloy door and window are arranged outside the prepreg wire unwinding device, comprising the prepreg wire unwinding device being arranged on the right side of the film wire unwinding device, the drive rewinding device being arranged on the upper side of the film wire unwinding device, the tension control device being arranged on the left side of the drive rewinding device, the motor rotor winding platform being arranged on the left side of the tension control device, the loading and unloading manipulator being arranged outside the motor rotor winding platform, and the prepreg wire unwinding device, the drive rewinding device, the tension control device, the film wire unwinding device, the motor rotor winding platform, the loading and unloading manipulator and the curing oven are all arranged inside the aluminum alloy door and window.

[0007] As a preferred embodiment of the present invention, the prepreg wire releasing device includes an unwinding spindle, a spindle tensioning rubber ring, a friction disk, a spindle fixing shaft, a friction belt, a tension spring and an adjusting screw. The prepreg wire releasing device fixes the prepreg spindle to the prepreg wire releasing device through the unwinding spindle and the spindle tensioning rubber ring. The unwinding spindle, the spindle tensioning rubber ring and the friction disk are all installed on the spindle fixing shaft. The friction belt is installed on the friction disk. The tension spring and the adjusting screw are both connected to the friction belt.

[0008] As a preferred solution of the present invention, the drive rewinding device includes a drive roller, a drive roller mounting seat, a synchronous gear, a drive motor, a passive roller, a spherical flange seat and a wire bundle, the drive roller is mounted on the drive roller mounting seat, the synchronous gear is mounted on the drive roller mounting seat, the passive roller is arranged on the right side of the drive roller, the wire bundle is wound around the drive roller and the passive roller, the spherical flange seat is mounted on the upper side of the passive roller, and the synchronous gear is mounted on the output end of the drive motor.

[0009] As a preferred solution of the present invention, the tension control device includes a motor rotor, a pneumatic tailstock, a pneumatic claw, a rotor driving motor, a front end winding reciprocating motor and a front end winding connecting plate. The motor rotor, pneumatic tailstock, pneumatic claw, rotor driving motor, front end winding reciprocating motor and front end winding connecting plate are all arranged in aluminum alloy doors and windows, the motor rotor is arranged between the pneumatic tailstock and the pneumatic claw, the front end winding reciprocating motor is connected to the front end winding connecting plate, and the rotor driving motor is connected to the belt.

[0010] As a preferred solution of the present invention, a front-end winding assembly fixing frame is arranged on the outside of the prepreg tape unwinding device, and the prepreg tape unwinding device, the driving rewinding device, the tension control device and the film unwinding device are all installed on the front-end winding assembly fixing frame.

[0011] As a preferred solution of the present invention, a floating control screen is installed on the aluminum alloy door and window.

[0012] As a preferred solution of the present invention, the prepreg tape unwinding device adopts a folded unwinding structure.

[0013] Beneficial Effects Compared with the prior art, the advantages of the present invention are: (1) In this scheme, the new jacket winding machine is a single-spindle prepreg tape winding machine, which includes the winding function of the prepreg tape and film to the motor rotor, as well as the automatic disassembly and assembly after the motor rotor is formed, and the heating and curing function, which can realize the continuous production of the motor rotor jacket winding molding as a whole. The modified equipment can achieve a maximum of 120KG constant tension winding and 80m / min high-speed winding, and the tension and wire width of the prepreg tape are always kept constant, without sliding friction and fuzzing, and the maximum speed is 80m / min. It provides a guarantee for the continuous, automated and stable production of high-tension, high-speed motor rotors.

[0014] (2) In this scheme, in order to solve the shortcomings of traditional and existing processes, a new winding method for sheathed motor rotors is designed. This method prepares prepreg tapes in advance and then directly winds the prepreg tapes onto the motor sleeve rotor. Since the prepreg tapes are professionally produced, the resin content can be accurately controlled to control the quality of the prepreg yarn, and the mechanical properties of the cured product have a smaller change. Compared with the existing process, this winding method can achieve a higher winding speed and improve the production efficiency of the components. The winding speed can reach up to 100m / min. The working environment is clean and tidy, there is no resin flow waste, and the operator can reduce the inhalation of toxic substances in the environment. At the same time, the quality and performance of the molded products can be better guaranteed.

[0015] (3) In this scheme, the selection of winding molding process parameters has a great influence on the performance of composite products. In order to improve the performance of winding molding composite materials, it is particularly important to optimize its main process parameters. The control of winding tension is an important process parameter in the winding process. The purpose is to make the fibers neatly and evenly wound onto the core mold, thereby ensuring the uniformity of tension between each fiber and each winding layer, and giving full play to the strength of carbon fiber. This winding method can increase the tension to a higher level, with a maximum tension of up to 120KG, thereby improving the strength of the motor rotor.

[0016] (4) In this scheme, the existing winding device is complex and poorly adapted, which is not compatible with the winding process, has a high resin waste rate, and has low fiber tension. High-efficiency and environmentally friendly high-tension precision winding is achieved simultaneously. The use of a guide wheel made of non-stick material reduces the risk of friction and fuzzing of the prepreg tape. The folding and releasing wire control structure achieves a stable width of the prepreg tape. The driving rewinding structure and tension control structure enable the prepreg tape to be wound onto the motor rotor at high speed and with constant ultra-high tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of a curing oven of the present invention; Figure 3 It is a schematic diagram of the structure of the prepreg tape unwinding assembly of the present invention; Figure 4 It is a schematic structural diagram of the driving rewinding device of the present invention; Figure 5 This is a first schematic diagram of the motor rotor winding platform structure of the present invention; Figure 6 This is a second schematic diagram of the motor rotor winding platform structure of the present invention.

[0018] Description of the numbers in the figure: 1. Prepreg tape unwinding device; 101. Unwinding spindle; 102. Spindle tensioning rubber ring; 103. Friction disk; 104. Spindle fixing shaft; 105. Friction belt; 106. Tension spring; 107. Adjusting screw; 2. Drive rewinding device; 201. Drive roller; 202. Drive roller mounting seat; 203. Synchronous gear; 204. Drive motor; 205. Passive roller; 206. Spherical flange seat; 207. Wire bundle; 3. Tension control device; 301. Motor rotor; 302. Pneumatic tailstock; 303. Pneumatic clamping claw; 304. Rotor drive motor; 305. Front end winding reciprocating motor; 306. Front end winding connecting plate; 4. Film unwinding device; 5. Motor rotor winding platform; 6. Loading and unloading manipulator; 7. Curing oven; 8. Suspended control panel; 9. Aluminum alloy doors and windows; 10. Front end winding component fixing frame. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Example: See also Figure 1-6 A novel motor rotor sheath winding system comprises a prepreg wire releasing device 1, a driving rewinding device 2, a tension control device 3, a film wire releasing device 4, a motor rotor winding platform 5, a loading and unloading manipulator 6 and a curing oven 7, an aluminum alloy door and window 9 is arranged outside the prepreg wire releasing device 1, the prepreg wire releasing device 1 is arranged on the right side of the film wire releasing device 4, the driving rewinding device 2 is arranged on the upper side of the film wire releasing device 4, the tension control device 3 is arranged on the left side of the driving rewinding device 2, the motor rotor winding platform 5 is arranged on the left side of the tension control device 3, the loading and unloading manipulator 6 is arranged on the outside of the motor rotor winding platform 5, the prepreg wire releasing device 1, the driving rewinding device 2, the tension control device 3, the film wire releasing device 4, the motor rotor winding platform 5, the loading and unloading manipulator 6 and the curing oven 7 are all arranged inside the aluminum alloy door and window 9.

[0021] In this embodiment, the sheath motor rotor winding system is composed of a prepreg tape unwinding device, a drive rewinding device, a tension control device, a film unwinding device, a motor rotor winding platform, a loading and unloading manipulator, and a curing oven. The prepreg tape unwinding device includes an unwinding spindle and a friction belt, and the friction belt provides initial tension during the prepreg tape unwinding process; the drive rewinding device includes a set of driving rollers, a set of passive rollers, etc., which are used to provide driving force for the filament bundle to move forward and give the filament bundle an increased tension value; the tension control device is composed of a weighing sensor and a guide wheel to control the tension value of the filament bundle winding process; the film unwinding device includes an unwinding spindle and a friction belt, and the friction belt provides initial tension during the film unwinding process; the motor rotor winding platform includes an electronic rotor fixing and rotating device and a reciprocating drive device of the front winding assembly; the loading and unloading manipulator is composed of a manipulator and a manipulator moving guide rail, the manipulator is used for automatic loading and unloading of the motor rotor, and the manipulator moving guide rail transfers the formed motor rotor to the curing oven; the curing oven is used for heating and curing the motor rotor sheath after forming; Furthermore, the prepreg unwinding device adopts a folding unwinding structure, and the unwinding axis is parallel to the wire path, so that the tow in the unwinding process offsets the reciprocating process in the unwinding process, reduces the friction and fuzzing of the prepreg and makes the overall wire width uniform during the unwinding process of the prepreg. Furthermore, the curing oven can store multiple groups of motor sheath rotors after winding at the same time, and the temperature is uniform and adjustable to complete the heating and curing of the motor rotor sheath; Furthermore, the front winding assembly and the motor rotor winding platform are installed into an integral frame, which adopts an aluminum alloy glass door and window structure to facilitate personnel observation; at the same time, it forms a closed structure to isolate the possible carbon fiber dust from damaging human health; Furthermore, the reciprocating drive device of the front-end winding assembly connects the winding assembly consisting of the front-end prepreg tape unwinding device, the driving rewinding device, the tension control device, and the film unwinding yarn rack to the motor rotor winding platform, thereby completing the horizontal winding of the prepreg tape and the film on the motor rotor.

[0022] Specifically, the prepreg wire unwinding device 1 includes an unwinding spindle shaft 101, a spindle shaft tensioning rubber ring 102, a friction disk 103, a spindle shaft fixing shaft 104, a friction belt 105, a tension spring 106 and an adjusting screw 107. The prepreg wire unwinding device 1 fixes the prepreg spindle to the prepreg wire unwinding device 1 through the unwinding spindle shaft 101 and the spindle shaft tensioning rubber ring 102. The unwinding spindle shaft 101, the spindle shaft tensioning rubber ring 102 and the friction disk 103 are all installed on the spindle shaft fixing shaft 104. The friction belt 105 is installed on the friction disk 103. The tension spring 106 and the adjusting screw 107 are both connected to the friction belt 105.

[0023] In this embodiment, the friction disc 103 generates mutual friction with the friction belt 105 to give the prepreg an initial tension. By adjusting the screw 107, the tension spring 106 generates different tensions, so that the friction between the friction disc 103 and the friction belt 105 changes, thereby adjusting the tension value of the prepreg.

[0024] Specifically, the driving rewinding device 2 includes a driving roller 201, a driving roller mounting seat 202, a synchronous gear 203, a driving motor 204, a passive roller 205, a spherical flange seat 206 and a filament bundle 207. The driving roller 201 is mounted on the driving roller mounting seat 202, the synchronous gear 203 is mounted on the driving roller mounting seat 202, the passive roller 205 is arranged on the right side of the driving roller 201, the filament bundle 207 is wound around the driving roller 201 and the passive roller 205, the spherical flange seat 206 is mounted on the upper side of the passive roller 205, and the synchronous gear 203 is mounted on the output end of the driving motor 204.

[0025] In this embodiment, the tow 207 is wound back and forth between the driving roller 201 and the passive roller 205 to obtain a high tension value. The driving roller 201 is mounted on the driving roller mounting seat 202, and rotated by the synchronous gear 203 and the driving motor 204. The passive roller 205 is mounted on the spherical flange seat 206. The spherical flange seat 206 can make the passive roller 205 and the driving roller 201 form a fixed angle. The angle makes the tow 207 wind back and forth between the two rollers to maintain the stability of the path; Furthermore, the tow is wound back and forth between the driving roller and the passive roller, and the tow will obtain a larger tension. The tension range of the tow can be controlled by controlling the number of winding turns. Furthermore, the surfaces of the driving roller and the passive roller are coated with Teflon anti-stick coating to prevent the prepreg tape from sticking to the roller surface; Furthermore, the weighing sensor is responsible for detecting the current tension value of the tow, and can be linked with the motor rotor fixed rotation device to accurately control the tension value of the tow. The detected tension value can be displayed on the screen as a curve to observe the tension fluctuation.

[0026] Specifically, the tension control device 3 includes a motor rotor 301, a pneumatic tailstock 302, a pneumatic clamping claw 303, a rotor driving motor 304, a front end winding reciprocating motor 305 and a front end winding connecting plate 306. The motor rotor 301, the pneumatic tailstock 302, the pneumatic clamping claw 303, the rotor driving motor 304, the front end winding reciprocating motor 305 and the front end winding connecting plate 306 are all arranged in the aluminum alloy door and window 9, the motor rotor 301 is arranged between the pneumatic tailstock 302 and the pneumatic clamping claw 303, the front end winding reciprocating motor 305 is connected to the front end winding connecting plate 306, and the rotor driving motor 304 is connected to the belt.

[0027] In this embodiment, after the loading and unloading manipulator 6 clamps the motor rotor 301 to the position shown in the figure, the pneumatic tailstock 302 and the pneumatic clamping claw 303 are tightened at the same time to complete the fixation of the motor rotor 301. The motor rotor 301 fixing device is connected to the rotor driving motor 304 through a belt, driving the rewinding device 2 to rotate and drive the motor rotor 301 to rotate axially; The prepreg tape unwinding device 1, the driving rewinding device 2, the tension control device 3 and the film unwinding device 4 are all installed on the front winding assembly fixing frame 10, and the front winding assembly fixing frame 10 is connected to the front winding reciprocating motor 305 through the front winding connecting plate 306; The entire winding device forms an integrated structure. The front winding reciprocating motor 305 controls the horizontal movement of the entire front winding system; Furthermore, the motor rotor fixing device is used to fix the motor rotor during the winding process, with a pneumatic clamping claw on one side and a pneumatic tailstock on the other side, and a pneumatic control system completes the automatic installation, fixing and disassembly of the motor rotor.

[0028] Furthermore, the motor rotor rotating device is used for the axial rotation of the motor rotor during the winding process, and adopts a servo system to accurately control the rotation speed of the rotor.

[0029] Specifically, a front-end winding assembly fixing frame 10 is provided on the outside of the prepreg tape unwinding device 1, and the prepreg tape unwinding device 1, the driving rewinding device 2, the tension control device 3 and the film unwinding device 4 are all installed on the front-end winding assembly fixing frame 10.

[0030] In this embodiment, a front-end winding assembly fixed frame 10 is provided on the outer side of the prepreg tape unwinding device 1, and the prepreg tape unwinding device 1, the driving rewinding device 2, the tension control device 3 and the film unwinding device 4 are all installed on the front-end winding assembly fixed frame 10, so that the entire winding equipment forms an integrated structure, and the front-end winding reciprocating motor 305 controls the horizontal movement of the entire front-end winding system.

[0031] Specifically, a floating control screen 8 is installed on the aluminum alloy door and window 9.

[0032] In this embodiment, a floating control screen 8 is installed on the aluminum alloy door and window 9.

[0033] Specifically, the prepreg tape unwinding device 1 adopts a folded unwinding structure.

[0034] In this embodiment, the prepreg tape unwinding device 1 adopts a folded unwinding structure.

[0035] Working principle: In order to solve the shortcomings of traditional and existing processes, a new sheath motor rotor winding method is designed. This method makes the prepreg tape in advance and then directly winds the prepreg tape onto the motor sleeve rotor. Since the prepreg tape is professionally produced, the resin content can be accurately controlled to control the quality of the prepreg yarn, and the mechanical properties of the cured product have a smaller change. Compared with the existing process, this winding method can achieve a higher winding speed, improve the production efficiency of the components, and the winding speed can reach up to 100m / min; the working environment is clean and tidy, there is no resin flow waste, and the operator inhalation of toxic substances in the environment can be reduced; at the same time, the quality and performance of the molded products can be better guaranteed; the new sheath winding machine is a single-spindle prepreg tape winding, including the winding function of the prepreg tape and film to the motor rotor, as well as the automatic disassembly and assembly after the motor rotor is formed, and the heating and curing function can realize the continuous production of the motor rotor sheath winding molding as a whole. The modified equipment can achieve a maximum of 120KG constant tension winding, 80m / min high-speed winding, and the tension and wire width of the prepreg tape are always kept constant, there is no sliding friction and fuzzing, and the maximum speed is 80m / min. It provides a guarantee for the continuous, automated and stable production of high-tension and high-speed motor rotors.

[0036] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and improved concepts of the present invention within the technical scope disclosed by the present invention, and they should be covered by the protection scope of the present invention.

Claims

1. A novel motor rotor sheath winding system, comprising a prepreg tape unwinding device (1), a drive rewinding device (2), a tension control device (3), a film unwinding device (4), a motor rotor winding platform (5), a loading and unloading manipulator (6) and a curing oven (7), characterized in that: An aluminum alloy door and window (9) is arranged outside the prepreg tape unwinding device (1), comprising: the prepreg tape unwinding device (1) is arranged on the right side of the film unwinding device (4); the drive rewinding device (2) is arranged on the upper side of the film unwinding device (4); the tension control device (3) is arranged on the left side of the drive rewinding device (2); the motor rotor winding platform (5) is arranged on the left side of the tension control device (3); the loading and unloading manipulator (6) is arranged outside the motor rotor winding platform (5); the prepreg tape unwinding device (1), the drive rewinding device (2), the tension control device (3), the film unwinding device (4), the motor rotor winding platform (5), the loading and unloading manipulator (6) and the curing oven (7) are all arranged inside the aluminum alloy door and window (9).

2. A novel motor rotor sheath winding system according to claim 1, characterized in that: The prepreg unwinding device (1) comprises an unwinding spindle shaft (101), a spindle shaft tightening rubber ring (102), a friction disk (103), a spindle shaft fixing shaft (104), a friction belt (105), a tension spring (106) and an adjusting screw (107). The prepreg unwinding device (1) fixes the prepreg spindle to the prepreg unwinding device (1) via the unwinding spindle shaft (101) and the spindle shaft tightening rubber ring (102). The unwinding spindle shaft (101), the spindle shaft tightening rubber ring (102) and the friction disk (103) are all mounted on the spindle shaft fixing shaft (104). The friction belt (105) is mounted on the friction disk (103). The tension spring (106) and the adjusting screw (107) are both connected to the friction belt (105).

3. A novel motor rotor sheath winding system according to claim 2, characterized in that: The drive rewinding device (2) comprises a drive roller (201), a drive roller mounting seat (202), a synchronous gear (203), a drive motor (204), a passive roller (205), a spherical flange seat (206), and a filament bundle (207); the drive roller (201) is mounted on the drive roller mounting seat (202); the synchronous gear (203) is mounted on the drive roller mounting seat (202); the passive roller (205) is arranged on the right side of the drive roller (201); the filament bundle (207) is wound around the drive roller (201) and the passive roller (205); the spherical flange seat (206) is mounted on the upper side of the passive roller (205); and the synchronous gear (203) is mounted on the output end of the drive motor (204).

4. A novel motor rotor sheath winding system according to claim 3, characterized in that: The tension control device (3) comprises a motor rotor (301), a pneumatic tailstock (302), a pneumatic clamping claw (303), a rotor driving motor (304), a front-end winding reciprocating motor (305) and a front-end winding connecting plate (306); the motor rotor (301), the pneumatic tailstock (302), the pneumatic clamping claw (303), the rotor driving motor (304), the front-end winding reciprocating motor (305) and the front-end winding connecting plate (306) are all arranged in the aluminum alloy door and window (9); the motor rotor (301) is arranged between the pneumatic tailstock (302) and the pneumatic clamping claw (303); the front-end winding reciprocating motor (305) is connected to the front-end winding connecting plate (306); and the rotor driving motor (304) is connected to a belt.

5. A novel motor rotor sheath winding system according to claim 4, characterized in that: A front-end winding assembly fixing frame (10) is arranged outside the prepreg tape unwinding device (1), and the prepreg tape unwinding device (1), the driving rewinding device (2), the tension control device (3) and the film unwinding device (4) are all mounted on the front-end winding assembly fixing frame (10).

6. A novel motor rotor sheath winding system according to claim 5, characterized in that: A suspended control screen (8) is installed on the aluminum alloy door and window (9).

7. A novel motor rotor sheath winding system according to claim 6, characterized in that: The prepreg tape unwinding device (1) adopts a folded unwinding structure.

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