A device and method for surface strengthening of a gear by direct current field assisted ultrasonic peening

Abstract

The application discloses a device for strengthening the surface of a gear by means of a direct-current electric field assisted ultrasonic shot peening, belongs to the technical field of gear design, and comprises a workbench, a target shaft and a shot peening shaft which are rotationally connected to the workbench, and the rotation axes of the target shaft and the shot peening shaft are arranged in a vertical direction; the target shaft is connected with a target gear, an amplitude changing rod is connected to the shot peening shaft, and a shot peening gear is arranged on the amplitude changing rod; an ultrasonic transducer for generating ultrasonic vibration of the amplitude changing rod is arranged on the amplitude changing rod; a shot particle circulating device is arranged on the workbench and is used for spraying shot particles to the target gear; a motor for driving the shot peening shaft to rotate is arranged on the workbench, and a synchronous belt for driving the target shaft and the shot peening shaft to synchronously rotate is arranged between the target shaft and the shot peening shaft; the shot peening gear is driven to vibrate ultrasonically, shot particles are driven to impact the surface of the gear at a high frequency, nanocrystalline is generated on the surface of the gear, the fatigue and wear performance of the surface of the gear is improved, and the problems of low efficiency and low residual stress of a traditional shot peening method are effectively solved.

Description

TECHNICAL FIELD

[0001] The application relates to the gear process field, in particular to a device for strengthening the surface of a gear by means of direct-current electric field assisted ultrasonic shot peening. BACKGROUND

[0002] Gears are important basic parts in the fields of automobiles, ships, wind power, aviation, aerospace, etc. Their working environment is complex, and they are required to have long service life and high reliability, which puts higher requirements on their material properties, surface treatment process, contact fatigue performance, bending fatigue performance and bonding performance. Aviation gears are key components of aeroengines, and their service life directly determines the service performance of the entire machine. With the rapid development of China's aerospace industry, the working environment of aviation gears is becoming increasingly harsh, and higher requirements are put forward for the load capacity and service life of gears. Contact fatigue failure is one of the main failure types of gears in service, which has multiple failure modes and complex failure mechanisms, and has many influencing factors, which seriously restricts the improvement of the fatigue performance and reliability of China's aviation gears.

[0003] In order to improve the fatigue and wear performance of the surface of the gear, a large number of researchers use shot peening to strengthen the surface of the gear. Zhang Yuanyuan of China Aeronautical Mianyang Research Institute of Materials and Technology invented a tooth surface shot peening strengthening method for spiral bevel gears [CN201911206804.6], and the tooth surface roughness meets the requirements after two shot peening treatments. The invention can effectively improve the tooth surface roughness, but the efficiency of two shot peening is low, and the residual stress is difficult to improve in the second shot peening process. Shao Wen of Central South University invented an ultrasonic shot peening strengthening device for gear parts [CN202210106251.2], which can realize ultrasonic shot peening strengthening treatment of the parts to be treated in cooperation with traditional shot peening equipment, and shot peening does not need to apply ultrasonic vibration. The invention combines ultrasonic vibration and shot peening for strengthening, but the ultrasonic vibration and shot peening have both enhancing and weakening effects in the coupling process, and the shot peening effect of the tooth surface is not obviously improved. Chen Haifeng of Hunan University of Science and Technology invented a pin-type gear ultrasonic shot peening strengthening device [CN202110473481.8], which uses a trapezoidal vibration head and a spring support rod to convert the axial movement into reciprocating movement in the direction of the processed gear tooth surface. When the invention uses the impact pin to impact the workpiece surface during processing, the processing efficiency is low and it is difficult to adapt to mass production, and the surface of complex parts may affect the transverse movement of the impact pin, and sometimes the uneven surface cannot be processed.

[0004] Therefore, it is necessary to invent a new gear surface shot peening strengthening device. SUMMARY

[0005] In order to effectively improve the fatigue and wear performance of the surface of the gear, the application provides a device for strengthening the surface of a gear by means of direct-current electric field assisted ultrasonic shot peening.

[0006] In a first aspect, the application provides a device for direct current field assisted ultrasonic shot peening of gear surface, which adopts the following technical scheme:

[0007] A device for direct current field assisted ultrasonic shot peening of gear surface comprises a workbench, a target shaft and a shot peening shaft are rotatably connected to the workbench, and the rotation axes of the target shaft and the shot peening shaft are arranged in the vertical direction; the target shaft is connected with a target gear, the shot peening shaft is connected with a horn, and the horn is provided with a shot peening gear; the horn is provided with an ultrasonic transducer for generating ultrasonic vibration of the horn;

[0008] A shot particle circulating device is arranged on the workbench, and the shot particle circulating device is used for spraying shot particles to the target gear; a gap is left between the shot peening gear and the target gear for the shot particles to pass through; a motor is arranged on the workbench for driving the shot peening shaft to rotate; and a synchronous belt is arranged between the shot peening shaft and the target shaft for driving the two to rotate synchronously.

[0009] By adopting the above technical scheme, the motor drives the target gear and the shot peening gear to rotate simultaneously, and the ultrasonic transducer drives the horn and the shot peening gear to generate ultrasonic vibration, so as to drive the shot particles to impact the surface of the target gear at a high frequency, cause dislocation and grain refinement of the surface tissue of the target gear, form a high residual compressive stress, and ensure a small surface roughness. In addition, the tooth surface structure of the shot peening gear can be adjusted, so that the distance between the surfaces of the shot peening gear and the target gear during rotation is not the same, and the distance is 20-30 mm, which is the best shot peening effect. Then, the residual stress of the meshing part of the target gear surface can be greater than that of other parts, so as to achieve the effect of precise shot peening. Compared with the patent documents mentioned in the background art, the application does not need to use a pneumatic shot peening device, the dust is small, and the energy utilization rate is high.

[0010] Optionally, two brush fixing rods for abutting against the target gear are arranged on the workbench, the two brush fixing rods are arranged on the baffles on the two sides of the workbench respectively, a brush is arranged on each brush fixing rod, and the brush is connected with a direct current power supply.

[0011] By adopting the above technical scheme, the brush can ensure that the target gear is in contact with the direct current power supply during rotation. The direct current power supply can provide a direct current of 100-500 A. Since the target gear rotates and the brush remains stationary, an alternating electric field is formed in the gear. According to the characteristics of metal materials, under the action of the electric field, the stress of the flow of metal materials inside is reduced due to electroplasticity, which is beneficial to the production of grain refinement, dislocation and subgrain, and nanocrystalline is more easily generated.

[0012] Optionally, the baffle on both sides of the workbench is provided with a groove for the vertical sliding of the brush fixing rod, and a plurality of positioning grooves for limiting the sliding of the brush fixing rod are arranged on the side wall of the groove in the vertical direction.

[0013] By adopting the above technical scheme, it is ensured that the brush can abut against the surface of the target gear well when machining gears with different tooth thicknesses.

[0014] Optionally, the pellet circulating device comprises a shot blasting gun, a connecting rod, a hinge, a pellet output pipeline, a pellet input pipeline, a shot blasting machine, a baffle and a collection plate, the collection plate is arranged below the target gear, the collection plate is arranged obliquely to collect pellets, the pellet input pipeline and the pellet output pipeline are respectively used for collecting pellets to the shot blasting machine and outputting pellets to the shot blasting gun, the hinge is fixed on the collection plate by bolts, the hinge is connected with the connecting rod, and the other end of the connecting rod is connected with the shot blasting gun.

[0015] By adopting the above technical scheme, the position of the shot blasting gun can be randomly adjusted, and it is ensured that the sprayed pellets can accurately enter between the target gear and the shot blasting gear, thereby facilitating the machining of gears of different sizes.

[0016] Optionally, the target shaft is provided with an insulating coupling, the insulating coupling is connected with a target mounting shaft, and the target gear is connected to the target mounting shaft.

[0017] By adopting the above technical scheme, the direct current electric field of the target gear is isolated.

[0018] Optionally, the vibration assembly comprises an ultrasonic transducer, a ring-shaped brush and an ultrasonic power supply, the ultrasonic transducer is connected with the amplitude transformer, the ring-shaped brush is sleeved on the ultrasonic transducer, and the ring-shaped brush is connected with the ultrasonic power supply.

[0019] By adopting the above technical scheme, when the ultrasonic power supply supplies power to the ultrasonic transducer, the ultrasonic transducer always rotates with the transmission shaft, so the ring-shaped brush is installed on the ultrasonic power supply to sleeve the ultrasonic transducer and continuously supply power to the ultrasonic transducer.

[0020] Optionally, the transmission assembly comprises a synchronous belt and two synchronous pulleys, the two synchronous pulleys are respectively installed on the target shaft and the shot blasting shaft through expansion pulleys, and the synchronous belt is installed on the two synchronous pulleys.

[0021] By adopting the above technical scheme, the synchronous belt drives the shot blasting shaft and the target shaft to rotate synchronously, and at the same time, the target shaft can also avoid ultrasonic vibration with the shot blasting shaft.

[0022] Optionally, the servo motor is connected with a transmission shaft through a shaft coupling, the transmission shaft is rotationally connected to the workbench, the rotation axis of the transmission shaft is arranged along the horizontal direction, a driven bevel gear is coaxially arranged on the shot blasting shaft, and a driving bevel gear is coaxially arranged on the transmission shaft and engaged with the driven bevel gear.

[0023] By adopting the technical scheme, the servo motor can smoothly transmit power to the shot blasting shaft.

[0024] In a second aspect, the application further provides a method for strengthening the surface of a gear by direct current electric field assisted ultrasonic shot blasting, and the following technical scheme is adopted:

[0025] A method for strengthening the surface of a gear by direct current electric field assisted ultrasonic shot blasting, which adopts the device for strengthening the surface of a gear by direct current electric field assisted ultrasonic shot blasting.

[0026] In summary, the application has the following beneficial technical effects:

[0027] The application transmits ultrasonic vibration of the shot blasting gear to shot particles by the arrangement of the shot blasting gear and the direct current power supply, the shot particles impact the target gear surface at a high frequency, which promotes the grain refinement, dislocation and subgrain generation of the gear surface layer, thereby generating nanocrystalline. Under the action of the direct current electric field and the rotation of the target gear, an alternating electric field can be generated inside the target gear. Due to the effect of electroplasticity, the flow stress inside the metal material is reduced, which is more conducive to the generation of nanocrystalline and the formation of large gradient residual stress. In addition, under the action of the electric field, the Joule heating effect is generated, the temperature rise causes the local melting of the crack tip inside the material, and the further expansion of the crack is prevented. The application can generate nanocrystalline in the surface layer of the gear and form large gradient residual stress, thereby improving the fatigue and wear performance of the gear surface and effectively solving the problems of low efficiency and low residual stress of the traditional shot blasting method. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the overall structure diagram of the device for strengthening the surface of a gear by direct current electric field assisted ultrasonic shot blasting according to the application;

[0029] Figure 2 is Figure 1 the partial structure diagram of the target shaft and the shot blasting shaft in

[0030] Figure 3 is Figure 1 the overall structure sectional view of

[0031] Figure 4 is Figure 1 the partial structure diagram of the workbench in

[0032] Figure 5 is Figure 1Fig. 2 is a partial structural view of the brush.

[0033] BRIEF DESCRIPTION OF DRAWINGS

[0034] 1, workbench; 2, driving assembly; 3, sheet metal assembly; 4, target gear and its transmission assembly; 5, direct current electric field device; 6, ultrasonic shot blasting gear and its transmission assembly; 7, shot circulating device; 21, servo motor; 22, motor mounting seat; 23, shaft coupling; 24, driving bevel gear; 25, driven bevel gear; 26, direct current power supply support; 27, direct current power supply; 28, expanding wheel; 29, synchronous belt; 210, insulating shaft coupling; 211, target gear; 212, locking nut; 213, shot blasting gear; 214, synchronous pulley; 215, rolling bearing seat; 31, transmission shaft; 32, shaft sleeve; 33, double-row bearing; 34, shot blasting shaft; 35, target shaft; 36, sealing ring; 37, target mounting shaft; 38, shot blasting gun; 39, connecting rod; 310, hinge; 311, shot output pipeline; 312, amplitude-changing rod; 313, ultrasonic transducer; 314, shot input pipeline; 315, shot blasting machine; 41, baffle; 42, positioning block; 43, collection plate; 44, annular brush; 45, ultrasonic power supply; 46, ultrasonic power supply support; 51, brush; 52, brush fixing rod. DETAILED DESCRIPTION

[0035] The following will be described in detail in combination with the accompanying drawings Figures 1-5 The present application will be further described in detail.

[0036] The embodiment of the present application discloses a device for reinforcing gear surface by direct current electric field assisted ultrasonic shot blasting, as shown in the drawings. Figure 1 The device for reinforcing gear surface by direct current electric field assisted ultrasonic shot blasting provided by the present application comprises a workbench 1, a driving assembly 2, an ultrasonic shot blasting gear and its transmission assembly 6, a target gear and its transmission assembly 4, a direct current electric field device 5, a shot circulating device 7 and a sheet metal assembly 3.

[0037] The driving assembly 2 is installed in front of the workbench 1 and used for driving the operation of the whole transmission system; the target gear and its transmission assembly 4 and the ultrasonic shot gear and its transmission assembly 6 are both installed on the workbench 1 through double-row bearings 33, the ultrasonic shot gear and its transmission assembly 6 are connected with the target gear and its transmission assembly 4 through the tooth structure of the synchronous belt 29 and the gear meshing, so that the shot gear 213 and the target gear 211 rotate synchronously and always keep a meshing gap of 5-30mm for shot processing; the direct current electric field device 5 is installed at the rear end of the workbench 1, the direct current power supply 27 is installed on the workbench 1 through the support 26 of the direct current power supply 27, the brush 51 on the direct current power supply 27 can always contact with the direct current power supply 27 in the rotating process of the target gear 211; the sheet metal assembly 3 is installed on the side of the workbench 1 through bolts, which plays a role in positioning and installing some parts, and the sheet metal assembly 3 is provided with an inclined structure below the gear for better collecting shot; the shot circulating device 7 is placed on the workbench 1 and located at the side of the driving assembly 2, which is used for collecting shot and shot function.

[0038] In the application, the workbench 1 is used for bearing the driving assembly 2, the sheet metal assembly 3, the target gear 211 and its transmission assembly 4, the direct current electric field device 5, the ultrasonic shot gear 213 and its transmission assembly 6, and the shot circulating device 7, and should have good rigidity, strength and stability.

[0039] As shown in Figure 2 and Figure 3 The transmission system of the application comprises a servo motor 21, a motor mounting seat 22, a shaft coupling 23, a driving bevel gear 24, a driven bevel gear 25, an expansion wheel 28, a synchronous belt 29, an insulation shaft coupling 210, a target gear 211, a locking nut 212, a shot gear 213, a synchronous belt 29 wheel, a rolling bearing seat 215, a transmission shaft 31, a shaft sleeve 32, a double-row bearing 33, a shot shaft 34, a target shaft 35, a target mounting shaft 37, an amplitude bar 312, an ultrasonic transducer 313.

[0040] The target shaft 35 is rotatably connected to the workbench 1, the target shaft 35 is fixedly connected to the target mounting shaft 37 through the insulation shaft coupling 210, the servo motor 21 is installed at the front end of the workbench 1 through the motor mounting seat 22 and bolts, the rotating shaft of the servo motor 21 is connected to the transmission shaft 31 through the shaft coupling 23, the rolling bearing seat 215 is installed on the workbench 1 through two bolts, which provides support and fixing effect for the transmission shaft, the transmission shaft 31 drives the shot shaft 34 through a pair of bevel gear pairs, the bevel gear pair comprises the driving bevel gear 24 and the driven bevel gear 25, the driving bevel gear 24 is installed at the rear end of the transmission shaft 31 through a key and a shaft shoulder, the driven bevel gear 25 is installed at the middle and lower end of the shot shaft 34 through the shaft sleeve 32 and a key, the shot shaft 34 and the target shaft 35 are installed at the bearing hole of the workbench 1 through two double-row bearings 33.

[0041] In order to transmit power from the transmission assembly of the shot blasting gear 213 to the transmission assembly of the target gear 211, the present application designs a synchronous belt 29 tooth structure between the two transmission assemblies, including two synchronous pulleys, a synchronous belt 29, and the two synchronous pulleys are respectively installed on the shot blasting shaft 34 and the target shaft 35 through two expansion pulleys 28 and shaft shoulders, and are ensured to be installed on a horizontal plane, and the synchronous belt 29 is installed on the two synchronous pulleys 214.

[0042] In order to isolate the direct current electric field on the target gear 211, the machined target gear 211 is installed on the transmission shaft and locked by the locking nut 212, the transmission shaft is connected with the transmission shaft through the insulating coupling 210, the insulating coupling 210 isolates the direct current electric field loaded on the target gear 211, the shot blasting gear 213 is installed on the amplitude lever 312 through the locking nut 212, the amplitude lever 312 is fixed on the ultrasonic transducer 313, the transducer is welded on the transmission shaft, and the shot blasting gear 213 and the target gear 211 are ensured to be located on a horizontal plane after installation, the tooth engagement gap of 5-30 mm can be ensured to exist at the gear engagement position by the synchronous belt 29 tooth structure, which is used for gear shot blasting, the ultrasonic transducer 313 converts the power output of the power supply into vibration output, transmits the vibration to the amplitude lever 312, and drives the shot blasting gear 213 to ultrasonic vibration, the amplitude lever 312 can drive the shot blasting gear 213 to generate ultrasonic vibration of 10-30 kHz frequency and 5-50 μm amplitude, thereby driving the shot blasting gear 213 to vibrate, and the shot blasting efficiency is greatly improved.

[0043] As shown in Figure 2 and Figure 5 The direct current electric field device 5 includes a direct current power supply 27 support 26, a direct current power supply 27, a brush 51, and a brush 51 fixing rod. The direct current power supply 27 is installed at the rear end of the workbench 1 through the direct current power supply 27 support 26 and bolts, the direct current power supply 27 is connected with the target gear 211 through the brush 51, the brush 51 wire passes through the two ring buckles of the collecting plate 43 and is connected with the brush 51, and the brush 51 fixing rod cooperates with the clamping groove structure of the baffle 41 to make the brush 51 keep a certain gap with the target gear 211, so that the brush 51 can always contact with the direct current power supply 27 in the rotating process of the target gear 211. The direct current power supply 27 can provide direct current, and since the target gear 211 rotates and the brush 51 remains stationary, an alternating electric field is formed in the gear. According to the characteristics of metal materials, under the action of the electric field, the stress of the metal internal material flow is reduced due to the electroplasticity, which is beneficial to the production of grain refinement, dislocation, and subgrain, and it is easier to generate nanocrystalline.

[0044] As shown in Figure 5As shown, the ultrasonic power supply device includes a ring brush 44, an ultrasonic power supply 45, and an ultrasonic power supply support 26; the sheet metal assembly 3 includes two side baffles 41, positioning blocks 42, and a collection plate 43.

[0045] The ultrasonic power supply 45 is mounted on the baffles 41 through the ultrasonic power supply 45 support 26 and bolts, and since the ultrasonic transducer 313 is always rotating with the shot blasting shaft 31 when the ultrasonic power supply 45 is supplying power to the ultrasonic transducer 313, the ring brush 44 is installed on the ultrasonic power supply 45 to cover the ultrasonic transducer 313, thereby continuously supplying power to the ultrasonic transducer 313.

[0046] The sheet metal assembly 3 is the housing part of the entire device, and many parts in the present application are installed on the sheet metal assembly 3. The ultrasonic power supply 45 support is mounted on the baffles 41, and each baffle 41 is fixed on the side of the workbench 1 through two bolts. The collection plate 43 has three square pins on each side, which are inserted into the three square holes of the baffles 41. The pin hole in the middle is matched with a positioning block 42, and the positioning block 42 is matched with a bolt to make the baffles 41 and the collection plate 43 more firmly assembled. The baffles 41 on both sides are provided with a clamping groove structure for adjusting the height of the brush 51 of the direct current power supply 27. As shown, the lower side of the collection plate 43 is inclined to the direction of the shot blasting gear 213, and a small hole is opened below the inclined side. The shot input pipe of the shot recycling device 7 is connected to the small hole. Such a structure makes the collection plate 43 better recover the shot after shot blasting. Two holes are opened below the collection plate 43 for passing through the amplitude lever 312 for installing the shot blasting gear 213 and the target mounting shaft 37 for installing the target gear 211, and sealing rings 36 are added at the matching parts of them and the collection plate 43 to prevent the shot from leaking out. A hinge 310 of a shot blasting gun 38 is fixed through a bolt at the front end of the collection plate 43.

[0047] The sheet metal assembly 3 of the present application is used to install other parts and forms a closed structure so that the shot is not splashed outside.

[0048] As Figure 3As shown, the pellet circulating device 7 comprises a shot gun 38, a connecting rod 39, a hinge 310, a pellet output pipeline 311, a pellet input pipeline 314, and a shot machine 315. The shot machine 315 is placed on the side of the driving assembly 2, and the two pipelines, the pellet input pipeline 314 and the pellet output pipeline 311, connected to the shot machine 315 are used to input the pellets collected in the collecting plate 43 into the shot machine 315 and output the pellets in the shot machine 315 to the shot gun 38, respectively. The hinge 310 is fixed on the collecting plate 43 by bolts, and the hinge 310 is connected to the connecting rod 39 by bolts. The other end of the connecting rod 39 is connected to the shot gun 38 by bolts. The angle of the connecting rod 39 and the shot gun 38 is adjusted so that the muzzle of the shot gun 38 is aligned with the meshing position of the shot gear 213 and the target gear 211, and then the hinge 310, the connecting rod 39 and the shot gun 38 are fixed by bolts.

[0049] The pellets used in the application can be stainless steel pellets, alloy pellets, cast steel pellets, cast iron pellets, glass pellets, and ceramic pellets, and the diameter of the pellets ranges from 0.5 mm to 2 mm. In order to obtain large residual stress and low surface roughness at the same time, large pellets and small pellets can be combined to perform shot blasting. The large pellets can form larger impact pits, and the small pellets can reduce the surface roughness.

[0050] The above are preferred embodiments of the application, and do not limit the protection scope of the application. Any equivalent changes made on the basis of the structure, shape, and principle of the application should be covered within the protection scope of the application.

Claims

1. A device for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field, characterized in that: The system includes a worktable (1), on which a target shaft (35) and a shot peening shaft (34) are rotatably connected. The rotation axes of the target shaft (35) and the shot peening shaft (34) are arranged in a vertical direction. A target gear (211) is connected to the target shaft (35), and an amplitude transformer (312) is connected to the shot peening shaft (34). A shot peening gear (213) is provided on the amplitude transformer (312). A vibration component that drives itself to generate ultrasonic vibration is provided on the amplitude transformer (312). The worktable (1) is equipped with a shot circulation device (7), which is used to spray shot onto the shot peening gear (213). A gap is left between the shot peening gear (213) and the target gear (211) for the shot to pass through. The worktable (1) is equipped with a servo motor (21) for driving the shot peening shaft (34) to rotate. A transmission assembly is provided between the shot peening shaft (34) and the target shaft (35) for driving the two to rotate synchronously. The workbench (1) is provided with two brush fixing rods (52), which are respectively set on both sides of the workbench (1). The brush fixing rods (52) are provided with brushes (51) for abutting the target gear (211), and the brushes (51) are connected to a DC power supply (27). An insulating coupling (210) is provided on the target shaft (35), and the insulating coupling (210) is connected to the target mounting shaft (37). The target gear (211) is connected to the target mounting shaft (37).

2. The device for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field according to claim 1, characterized in that: The workbench (1) has a groove for the brush fixing rod (52) to slide in the vertical direction, and the side wall of the groove has a plurality of positioning grooves at intervals in the vertical direction to restrict the sliding of the brush fixing rod (52).

3. The device for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field according to claim 1, characterized in that: The shot circulation device (7) includes a shot peening gun (38), a connecting rod (39), a hinge (310), a shot output pipe (311), a shot input pipe (314), a shot peening machine (315), and a collecting plate (43). The shot input pipe (314) and the shot output pipe (311) are used to collect shot to the shot peening machine (315) and output shot to the shot peening gun (38), respectively. The collecting plate (43) is located below the target gear (211). The collecting plate (43) is inclined to collect shot. The hinge (310) is fixed to the collecting plate (43) by bolts. The hinge (310) is connected to the connecting rod (39). The other end of the connecting rod (39) is connected to the shot peening gun (38).

4. The device for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field according to claim 1, characterized in that: The vibration assembly includes an ultrasonic transducer (313), an annular brush (44), and an ultrasonic power supply (45). The ultrasonic transducer (313) is connected to the amplitude transformer (312), and the annular brush (44) is sleeved on the ultrasonic transducer (313). The annular brush (44) is connected to the ultrasonic power supply (45).

5. The device for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field according to claim 1, characterized in that: The transmission assembly includes a timing belt (29) and two timing pulleys (214). The two timing pulleys (214) are respectively mounted on the target shaft (35) and the shot peening shaft (34) via tensioning pulleys (28). The timing belt (29) is mounted on the two timing pulleys (214).

6. The device for strengthening the surface of gears by DC electric field-assisted ultrasonic shot peening according to claim 1, characterized in that: The servo motor (21) is connected to a drive shaft (31) via a coupling (23). The drive shaft (31) is rotatably connected to the worktable (1). The rotation axis of the drive shaft (31) is set in the horizontal direction. A driven bevel gear (25) is coaxially arranged on the shot peening shaft (34). A driving bevel gear (24) is coaxially arranged on the drive shaft (31). The driving bevel gear (24) meshes with the driven bevel gear (25).

7. A method for strengthening the surface of gears by ultrasonic shot peening assisted by a DC electric field, characterized in that: The method employs the DC electric field-assisted ultrasonic shot peening device for strengthening the gear surface as described in any one of claims 1-6.

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