Automatic focusing focused ultrasonic rotating surface strengthening device and method

Abstract

The invention discloses an automatic focusing focused ultrasonic rotating surface strengthening device which comprises a multi-axis motion platform, an electric control system, an ultrasonic power supply, a medium tank and a rotating strengthening system. An underwater angle encoder and a laser displacement sensor measure and feed back angle and distance information of a focused ultrasonic transducer, and an electric control system controls a micro motor and a servo motor to carry out position fine adjustment, so that a focus of the focused ultrasonic transducer is located at a solid-liquid interface of a workpiece and a medium and is located on a central axis of a rotating main shaft at the same time; according to the structural characteristics of the workpiece, a strengthening track is planned in cooperation with the multi-degree-of-freedom motion of the multi-axis motion platform; a reinforced area formed by oblique focusing of the focused ultrasonic transducer is crescent-shaped, the crescent-shaped reinforced area is changed into a rotationally symmetrical Gaussian-like distribution shape through rotation around the central axis of the rotating main shaft, and an impact function of the reinforced area is a Gaussian-like function. And then large-area strengthening of the surface of the workpiece is achieved through track motion of the multi-axis motion platform.

Description

Technical Field

[0001] The present invention is applied to the field of surface engineering technology, and particularly designs an automatic focusing focused ultrasonic rotating surface strengthening device and method. Background Art

[0002] Failure of mechanical parts will lead to abnormal operation of various mechanical equipment, which may affect the work quality and efficiency, or even lead to the scrapping of mechanical equipment and even cause engineering accidents, causing serious impact on the national economy and personal safety. In order to make the parts obtain high-performance surfaces, surface strengthening technology came into being, and has made great progress in the research of domestic and foreign scholars and the practical application of engineering projects. Surface strengthening technology is to use mechanical processing, chemical heat treatment and surface coating to treat the surface of parts, so that the surface of parts can obtain different organizational structures and properties from the matrix material, thereby improving the wear resistance, corrosion resistance and fatigue strength of the parts, so that the parts can obtain better comprehensive mechanical properties. Traditional surface strengthening technologies include rolling, shot peening, extrusion, etc. With the development of special processing technology, researchers have tried to introduce ultrasound on the basis of traditional surface strengthening technology, using the vibration effect and cavitation effect of ultrasound to improve the strengthening conditions, enhance the strengthening effect, and improve the strengthening efficiency. At present, the commonly used ultrasonic surface strengthening technologies include ultrasonic shot peening, ultrasonic rolling, ultrasonic vibration extrusion, ultrasonic electric pulse assisted processing, ultrasonic surface modification, etc.

[0003] Traditional surface strengthening technology is mature and has been industrialized. However, it requires complex process equipment, resulting in high costs or environmental pollution due to its own process characteristics, low efficiency, and difficult to control strengthening effects. The introduction of ultrasonic cavitation improves the conditions in the strengthening process, making the workpiece more evenly stressed, improving the strengthening effect and efficiency, but the traditional surface strengthening technology is still at work. In addition, ultrasonic surface strengthening technologies such as ultrasonic extrusion and rolling use ultrasonic amplitude transformers to form high-frequency impacts on the surface, and their ultrasonic frequency ranges are mostly low-frequency ultrasounds of 20-45KHz. There are the following limitations: first, the static pressure parameters of the amplitude transformer need to be precisely adjusted, otherwise the strengthening effect will be uneven; second, the shape and size of the workpiece to be strengthened are strictly restricted, otherwise the strengthening effect cannot be achieved; third, the use of complex equipment and coolants will cause certain pollution to the environment.

[0004] As a special processing strengthening method newly proposed in recent years, the related equipment and devices for focused ultrasonic surface strengthening are still immature. The ultrasonic wave is focused into the medium by a focused ultrasonic transducer, and a strong acoustic cavitation phenomenon is generated in the focal area, thereby forming high temperature, high pressure, micro-jet, shock wave, etc. to impact strengthen the surface of the workpiece. This method has improved the shortcomings of traditional ultrasonic surface strengthening technology to a certain extent, but due to the nonlinear change of the focused ultrasonic sound field at the liquid-solid interface, the shape of the cavitation cloud in the focal area is constantly changing during the entire strengthening process. Therefore, the surface hardness, residual stress, hardened layer depth, surface roughness, etc. at different positions in the focal area are quite different, and the surface performance unevenness of the strengthening area formed by the cavitation collapse impact is very serious.

[0005] In addition, for the focused ultrasonic surface enhancement method, the focused ultrasonic transducer is not suitable for vertical placement. The reason is that, on the one hand, the incident wave and the reflected wave superimpose on each other and affect the acoustic field characteristics, which in turn affects the enhancement effect of the enhanced area; on the other hand, the reflected wave propagates to the focused ultrasonic transducer, causing the focused ultrasonic transducer to heat up severely or even burn out. The enhanced area formed by the tilted focused ultrasonic transducer after focusing is in the shape of a crescent, such as Fig.11 When the tilted focused ultrasonic transducer is enhanced after trajectory planning, the surface performance inhomogeneity of the enhanced area is also very serious. Summary of the invention

[0006] In view of the above-mentioned prior art, in order to overcome the disadvantage of serious non-uniformity of surface performance of the strengthening area formed by cavitation collapse impact in the current focused ultrasonic surface strengthening method, and at the same time improve the practicality and efficiency of the focused ultrasonic surface strengthening method, the present invention proposes an automatic focusing focused ultrasonic rotating surface strengthening device and method.

[0007] In order to solve the above technical problems, the present invention proposes an automatic focusing focused ultrasonic rotating surface strengthening device, comprising a multi-axis motion platform, an electric control system, an ultrasonic power supply, a dielectric tank and a rotating strengthening system;

[0008] The rotation strengthening system is composed of a rotating spindle, a hollow conductive slip ring, a rotating mounting beam, a micro motor, a lead screw sliding mechanism, a motor mounting plate, a servo motor, a transducer fixture, a focused ultrasonic transducer, an underwater angle encoder and a laser displacement sensor;

[0009] The rotation strengthening system is installed on the main shaft of the multi-axis motion platform through the upper end of the rotation main shaft, the electric control system and the ultrasonic power supply supply power and receive feedback information for the rotation strengthening system through the hollow conductive slip ring, the workpiece is fixed at the bottom of the medium tank and is located below the rotation strengthening system; the rotation main shaft passes through the inside of the hollow conductive slip ring and is fixedly connected to the rotor of the hollow conductive slip ring, and the stator of the hollow conductive slip ring is installed on the multi-axis motion platform; the rotation mounting beam is installed at the end of the rotation main shaft, the lead screw sliding mechanism is embedded in the rotation mounting beam, and a micro motor is installed on the back of the lead screw sliding mechanism; the transducer fixture is connected to the lead screw sliding mechanism through a hinge, the rotor of the servo motor is fixedly connected to the transducer fixture, the stator of the servo motor is fixedly connected to the lead screw sliding mechanism through the motor mounting plate, and the focused ultrasonic transducer is installed on the transducer fixture; the underwater angle encoder is installed at the tail of the servo motor, and the laser displacement sensor is installed in the middle of the rotation mounting beam;

[0010] The electric control system measures and feeds back the position information of the focused ultrasonic transducer according to the underwater angle encoder and the laser displacement sensor, and performs position fine-tuning to realize automatic focusing; the focused ultrasonic transducer realizes revolution around the central axis of the rotating main shaft through the linkage of the rotating main shaft and the rotating mounting beam; the micro motor, the servo motor, the underwater angle encoder and the laser displacement sensor are powered by the electric control system through the hollow conductive slip ring during the rotation process, and the focused ultrasonic transducer is powered by the ultrasonic power supply through the hollow conductive slip ring during the rotation process.

[0011] Furthermore, the focused ultrasonic rotating surface strengthening device of the present invention comprises:

[0012] The motion axis of the lead screw sliding mechanism and the rotation center axis of the transducer fixture around the hinge connection are on the same plane N, and the center axis of the rotating spindle is perpendicular to the plane N; the intersection of the spherical surface of the focused ultrasonic transducer and the connection structure is point A, the focal length f of the focused ultrasonic transducer and the distance between point A and the rotation center of the transducer fixture around the hinge connection are a, the distance from the intersection of the center axis of the rotating spindle and the plane N to the workpiece surface is b, the distance between the rotation center axis of the transducer fixture around the hinge and the center axis of the rotating spindle is c, the rotation angle of the focused ultrasonic transducer is θ, and satisfies: b 2 +c 2 =(a+f) 2, wherein c = (a + f) cos θ, b = (a + f) sin θ; the electronic control system fine-tunes the position of the focused ultrasonic transducer to achieve automatic focusing according to the rotation angle θ and distance b measured and fed back by the underwater angle encoder and the laser displacement sensor.

[0013] The micro motor and the lead screw sliding mechanism are used for power transmission of staggered axes, and the transmission mechanism used is a staggered axis gear pair or a worm gear pair, so as to realize the radial translation of the focused ultrasonic transducer.

[0014] The rotation angle θ of the focused ultrasonic transducer is adjusted by the servo motor, thereby changing the incident angle of the sound wave of the focused ultrasonic surface enhancement, and the incident angle is 30° to 60°.

[0015] The focused ultrasonic transducer is one or more of an acoustic lens, a self-focused ultrasonic transducer, and an array transducer.

[0016] The ultrasonic power supply generates high-frequency ultrasound of 200 KHz to 10 MHz.

[0017] The medium in the medium tank is a liquid medium that can generate ultrasonic cavitation phenomenon under high-frequency focused ultrasound or a suspension medium containing solid particles.

[0018] At the same time, the present invention also proposes a focused ultrasonic rotating surface strengthening method that uses the above-mentioned focused ultrasonic rotating surface strengthening device to achieve automatic focusing, and the specific process includes:

[0019] At the beginning of strengthening, the workpiece is fixed at the bottom of the medium tank; the electronic control system, the underwater angle encoder and the laser displacement sensor are started, and the electronic control system fine-tunes the position of the focused ultrasonic transducer according to the rotation angle θ and the distance b measured and fed back by the underwater angle encoder and the laser displacement sensor, so that the focus of the focused ultrasonic transducer is simultaneously located at the solid-liquid interface between the workpiece and the medium and on the central axis of the rotating spindle;

[0020] Pouring a medium into the medium tank, wherein the medium in the medium tank immerses the focused ultrasonic transducer;

[0021] According to the geometric shape and size of the workpiece to be strengthened, the strengthening trajectory is planned by the multi-axis motion platform; the multi-axis motion platform is started to drive the rotation spindle to rotate, thereby driving the rotation strengthening system to rotate;

[0022] The ultrasonic power supply is started, and the rotating focused ultrasonic transducer is powered through the hollow conductive slip ring; the focused ultrasonic transducer focuses the ultrasonic vibration on the strengthening area of ​​the workpiece to be strengthened, and a strong acoustic cavitation phenomenon is generated at the focus, thereby forming high temperature, high pressure, micro-jet, and shock wave, which have an impact strengthening effect on the surface of the workpiece; the strengthening area at the focus is rotationally symmetric, the strengthening impact function is a Gaussian-like function, and the strengthening area presents a Gaussian-like distribution. Different strengthening effects can be achieved by controlling the dwell time of the focused ultrasonic transducer, and the focused ultrasonic transducer completes the strengthening of all areas of the workpiece surface according to a preset strengthening trajectory.

[0023] Furthermore, in the focused ultrasonic rotating surface strengthening method described in the present invention, the strengthening area formed by the oblique focusing of the focused ultrasonic transducer is crescent-shaped, and the crescent-shaped strengthening area is transformed into a rotationally symmetric Gaussian-like distribution shape by rotating around the central axis of the rotating spindle, and the impact function of the strengthening area is a Gaussian-like function, and then the large-area strengthening of the workpiece surface is achieved through the trajectory motion of the multi-axis motion platform.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The focused ultrasonic rotation surface strengthening method proposed in the present invention has a crescent-shaped strengthening area formed by the oblique focusing of the focused ultrasonic transducer. The strengthening area is transformed into a rotationally symmetrical Gaussian distribution shape by rotating around the central axis of the rotating spindle. The impact function of the strengthening area is a Gaussian-like function. The trajectory motion of the multi-axis motion platform is used to achieve large-area strengthening of the workpiece surface, which greatly improves the uniformity of the strengthening effect (surface hardness, hardened layer depth, residual stress, surface roughness, etc.) of the strengthening area.

[0026] (2) The focused ultrasonic rotating surface strengthening device proposed in the present invention has an automatic focusing function, which is achieved through a multi-axis motion platform and an electronic control system, so that the focus of the focused ultrasonic transducer is located at the solid-liquid interface between the workpiece and the medium, and at the same time is located on the central axis of the rotating spindle, which is convenient for technicians to operate and improves the practicability of the focused ultrasonic surface strengthening method.

[0027] (3) In the focused ultrasonic rotating surface strengthening device proposed in the present invention, the arrangement of the focused ultrasonic transducers can be symmetrical or in an array, thereby improving the strengthening efficiency of the focused ultrasonic surface strengthening method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the embodiment 1 of the auto-focusing focused ultrasonic rotating surface strengthening device of the present invention;

[0029] Figure 2 for Figure 1The schematic diagram of the positive and side structure of the rotation strengthening system shown in;

[0030] Figure 3 for Figure 2 A schematic diagram of the dorsal structure of the rotation strengthening system shown;

[0031] Figure 4 Schematic diagram of the principle of auto-focusing focused ultrasonic rotating surface enhancement;

[0032] Figure 5 A schematic diagram of the shape of the strengthening area of ​​the focused ultrasonic rotation surface strengthening method of the present invention;

[0033] Figure 6 Schematic diagram of Gaussian-like distribution for the enhanced region;

[0034] Figure 7 Schematic diagram of possible trajectory planning for a multi-axis motion platform Figure 1 ;

[0035] Figure 8 Schematic diagram of possible trajectory planning for a multi-axis motion platform Figure 2 ;

[0036] Fig. 9 For the general Figure 1 A schematic structural diagram of Embodiment 2 in which the focused ultrasonic transducers are symmetrically arranged as shown in FIG.

[0037] Fig.10 This is a schematic diagram of the industrial robot structure;

[0038] Fig.11 It is a schematic diagram of the surface of the enhanced area formed after focusing of an inclined focused ultrasonic transducer in the prior art. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0040] like Figure 1 As shown, an auto-focusing focused ultrasonic rotating surface strengthening device proposed by the present invention includes a multi-axis motion platform 1, an electric control system 2, an ultrasonic power supply 3, a dielectric tank 15 and a rotating strengthening system.

[0041] like Figure 2 and Figure 3 As shown, the rotation strengthening system consists of a rotating spindle 4, a hollow conductive slip ring 5, a rotating mounting beam 6, a micro motor 7, a lead screw sliding mechanism 8, a motor mounting plate 9, a servo motor 10, a transducer fixture 11, a focused ultrasonic transducer 12, an underwater angle encoder 13 and a laser displacement sensor 14.

[0042] like Figure 1As shown, the rotation strengthening system is installed on the main shaft of the multi-axis motion platform 1 through the upper end of the rotating main shaft 4, the electric control system 2 and the ultrasonic power supply 3 supply power to the rotation strengthening system and receive feedback information through the hollow conductive slip ring 5, and the workpiece 16 is fixed at the bottom of the medium slot 15 and is located below the rotation strengthening system.

[0043] like Figure 2 and Figure 3 As shown, the rotating main shaft 4 passes through the inside of the hollow conductive slip ring 5 and is fixedly connected to the rotor of the hollow conductive slip ring 5, and the stator of the hollow conductive slip ring 5 is installed on the multi-axis motion platform 1. The rotating mounting beam 6 is installed at the end of the rotating main shaft 4, the lead screw sliding mechanism 8 is embedded in the rotating mounting beam 6, and the micro motor 7 is installed on the back of the lead screw sliding mechanism 8; the transducer fixture 11 is connected to the lead screw sliding mechanism 8 through a hinge, the rotor of the servo motor 10 is fixedly connected to the transducer fixture 11, and the stator of the servo motor 10 is fixedly connected to the lead screw sliding mechanism 8 through the motor mounting plate 9, and the focused ultrasonic transducer 12 is installed on the transducer fixture 11, and the focused ultrasonic transducer 12 is an acoustic lens, a self-focusing ultrasonic transducer, an array transducer or other types of ultrasonic transducers, and can also be a combined transducer that matches each other.

[0044] like Figure 2 As shown, the underwater angle encoder 13 is installed at the tail of the servo motor 10 , and the laser displacement sensor 14 is installed in the middle of the rotating mounting beam 6 .

[0045] The electronic control system 2 measures and feeds back the position information of the focused ultrasonic transducer 12 according to the underwater angle encoder 13 and the laser displacement sensor 14, and performs position fine-tuning to achieve automatic focusing; the focused ultrasonic transducer 12 realizes revolution around the central axis of the rotating main shaft 4 through the linkage of the rotating main shaft 4 and the rotating mounting beam 6.

[0046] like Figure 2 As shown, the micro motor 7, the servo motor 10, the underwater angle encoder 13 and the laser displacement sensor 14 are powered by the electric control system 2 through the hollow conductive slip ring 5 during the rotation process, and the focused ultrasonic transducer 12 is powered by the ultrasonic power supply 3 through the hollow conductive slip ring 5 during the rotation process. In the present invention, the ultrasonic power supply 3 generates high-frequency ultrasound of 200KHz to 10MHz.

[0047] like Figure 2 and Figure 4As shown, in the present invention, the movement axis of the screw sliding mechanism 8 and the rotation center axis of the transducer fixture 11 around the hinge connection are on the same plane N, and the center axis of the rotating spindle 4 is perpendicular to the plane N; the intersection of the spherical surface of the focused ultrasonic transducer 12 and the connection structure is point A, the focal length f of the focused ultrasonic transducer 12, the distance between point A and the rotation center of the transducer fixture 11 around the hinge connection is a, the distance from the intersection of the center axis of the rotating spindle 4 and the plane N to the surface of the workpiece 16 is b, the distance between the rotation center axis of the transducer fixture 11 around the hinge and the center axis of the rotating spindle 4 is c, the rotation angle of the focused ultrasonic transducer 12 is θ, and satisfies: b 2 +c 2 =(a+f) 2 , where c = (a + f) cosθ, b = (a + f) sinθ; the electronic control system 2 fine-tunes the position of the focused ultrasonic transducer 12 to achieve automatic focusing according to the rotation angle θ and distance b measured and fed back by the underwater angle encoder 13 and the laser displacement sensor 14. The rotation angle θ of the focused ultrasonic transducer 12 is adjusted by the servo motor 10, thereby changing the incident angle of the sound wave of the focused ultrasonic surface enhancement, and the incident angle is 30° to 60°.

[0048] In the present invention, the micro motor 7 and the lead screw sliding mechanism 8 are used for staggered axis power transmission, and the transmission mechanism used is a staggered axis gear pair or a worm gear pair, so as to realize the radial translation of the focused ultrasonic transducer 12. In the present invention, it can be realized by using, but not limited to, a bevel gear or worm gear transmission mechanism.

[0049] The present invention discloses an auto-focusing focused ultrasonic rotating surface strengthening method, wherein the device of the present invention realizes the revolution of the focused ultrasonic transducer 12 around the central axis of the rotating spindle 4; the underwater angle encoder 13 and the laser displacement sensor 14 measure and feedback the angle and distance information of the focused ultrasonic transducer 12, and the electronic control system 2 controls the micro motor 7 and the servo motor 10 to perform position fine adjustment, so that the focus of the focused ultrasonic transducer 12 is located at the solid-liquid interface between the workpiece 16 and the medium, and is located on the central axis of the rotating spindle 4; then, according to the structural characteristics of the workpiece 16, the multi-degree-of-freedom motion of the multi-axis motion platform 1 is coordinated to plan the strengthening trajectory, and the surface strengthening of the workpiece 16 is completed. The strengthening area at the focus is rotationally symmetric, the strengthening impact function is a Gaussian-like function, and the strengthening area presents a Gaussian-like distribution. Different strengthening effects can be achieved by controlling the dwell time of the focused ultrasonic transducer 12.

[0050] At the beginning of strengthening, the workpiece 16 is fixed at the bottom of the medium tank 15; the electronic control system 2, the underwater angle encoder 13 and the laser displacement sensor 14 are started, and the electronic control system 2 fine-tunes the position of the focused ultrasonic transducer 12 according to the rotation angle θ and the distance b measured and fed back by the underwater angle encoder 13 and the laser displacement sensor 14, so that the focus of the focused ultrasonic transducer 12 is simultaneously located at the solid-liquid interface between the workpiece 16 and the medium and on the central axis of the rotating spindle 4.

[0051] A medium is poured into the medium tank 15 , and the medium is a liquid medium that can generate ultrasonic cavitation under high-frequency focused ultrasound or a suspension medium containing solid particles. For example, it can be a liquid medium such as water or glycerin. The focused ultrasonic transducer 12 is completely immersed in the medium in the medium tank 15 .

[0052] According to the geometric shape and size of the workpiece 16 to be strengthened, the strengthening trajectory is planned by the multi-axis motion platform 1; the multi-axis motion platform 1 is started to drive the rotating spindle 4 to rotate, thereby driving the rotation strengthening system to rotate.

[0053] The ultrasonic power supply 3 is started, and the rotating focused ultrasonic transducer 12 is powered through the hollow conductive slip ring 5. The focused ultrasonic transducer 12 focuses the ultrasonic vibration on the strengthening area of ​​the workpiece 16 to be strengthened, and a strong acoustic cavitation phenomenon is generated at the focus, thereby forming high temperature, high pressure, micro jets, shock waves, etc. to produce impact strengthening effects on the surface of the workpiece; the strengthening area at the focus is rotationally symmetrical, the strengthening impact function is a Gaussian-like function, and the strengthening area presents a Gaussian-like distribution. Different strengthening effects are achieved by controlling the dwell time of the focused ultrasonic transducer 12, and the focused ultrasonic transducer 12 completes the strengthening of all areas on the surface of the workpiece 16 according to the preset strengthening trajectory.

[0054] like Figure 5 As shown, the strengthening area formed by the oblique focusing of the focused ultrasonic transducer 12 is crescent-shaped. The crescent-shaped strengthening area is transformed into a rotationally symmetrical Gaussian-like distribution shape by rotating around the central axis of the rotating spindle 4. The impact function of the strengthening area is a Gaussian-like function, and then the trajectory motion of the multi-axis motion platform 1 realizes large-area strengthening of the surface of the workpiece 16.

[0055] The basic steps of the strengthening method described in the present invention are as follows:

[0056] Step 1: Select the type of medium and the type, frequency and focal length of the focused ultrasonic transducer 12 according to the structural features (geometry and size) of the workpiece 16 and the strengthening requirements. Install the focused ultrasonic transducer 12 on the transducer fixture 11 and fix the workpiece 16 at the bottom of the medium tank 15.

[0057] Step 2: predefine the relationship between the focal length f of the focused ultrasonic transducer 12, the distance a from point A to the rotation center of the transducer fixture 11 around the hinge connection, the distance c from the rotation center axis of the transducer fixture 11 around the hinge and the central axis of the rotating spindle 4, the distance b from the intersection of the central axis of the rotating spindle 4 and the plane N to the surface of the workpiece 16, and the rotation angle θ of the focused ultrasonic transducer 12. Satisfy the geometric relationship: b 2 +c 2 =(a+f) 2 , c = (a + f) cos θ, b = (a + f) sin θ. The corresponding functional relationship is then converted into code and written into the multi-axis motion platform 1 and the electronic control system 2 to start and complete the automatic focusing.

[0058] Step 3: Analyze the structural features of the workpiece 16 to plan the trajectory, including the movement speed, movement direction, and strengthening time of the focused ultrasonic transducer 12 . Convert the planned trajectory into code and write it into the multi-axis motion platform 1 . Figure 7 and Figure 8 The schematic diagram of trajectory planning that can be adopted by the multi-axis motion platform 1 is shown. In the strengthening method described in the present invention, as for how to perform trajectory planning according to the structural characteristics of the workpiece, it is mainly to consider the overlap of the trajectories according to the size of the strengthening area, and then to cover the entire surface. This belongs to the common knowledge in the technical field and will not be repeated in the present invention.

[0059] Step 4: Pour the medium into the medium tank 15, and the medium needs to immerse the entire focused ultrasonic transducer 12. Start the ultrasonic power supply 3, and complete the strengthening of the entire surface area of ​​the workpiece 16 according to the preset strengthening trajectory.

[0060] In the present invention, the enhanced area formed by the oblique focusing of the focused ultrasonic transducer 12 is in a crescent shape, which is transformed into a rotationally symmetrical Gaussian-like distribution shape by rotating around the central axis of the rotation main axis 4, such as Figure 5 and Figure 6 As shown, the impact function of the strengthened area is a Gaussian-like function, and the large-area strengthening of the surface of the workpiece 16 is achieved through the trajectory motion of the multi-axis motion platform 1.

[0061] Example 1

[0062] according to Figure 1 The system structure shown is installed. The type of medium and the type, frequency and focal length of the focused ultrasonic transducer 12 are selected according to the structural characteristics (geometry and size) of the workpiece 16 and the strengthening requirements. The focused ultrasonic transducer 12 is installed on the transducer fixture 11, and the workpiece 16 is fixed at the bottom of the medium tank 15.

[0063] The relationship between the focal length f of the focused ultrasonic transducer 12, the distance a from point A to the rotation center of the transducer fixture 11 around the hinge connection, the distance c from the rotation center axis of the transducer fixture 11 around the hinge and the central axis of the rotating spindle 4, the distance b from the intersection of the central axis of the rotating spindle 4 and the plane N to the surface of the workpiece 16, and the rotation angle θ of the focused ultrasonic transducer 12 is predefined. The geometric relationship is satisfied: b 2 +c 2 =(a+f) 2 , c = (a + f) cos θ, b = (a + f) sin θ. The corresponding functional relationship is then converted into code and written into the multi-axis motion platform 1 and the electronic control system 2 to start and complete the automatic focusing.

[0064] The structural features of the workpiece 16 are analyzed to plan the trajectory, including the movement speed, movement direction, and strengthening time of the focused ultrasonic transducer 12 . The planned trajectory is converted into a code and written into the multi-axis motion platform 1 .

[0065] Pour the medium into the medium tank 15, and the medium needs to immerse the entire focused ultrasonic transducer 12. Start the ultrasonic power supply 3, and supply power to the rotating focused ultrasonic transducer 12 through the hollow conductive slip ring 5. The focused ultrasonic transducer 12 focuses the ultrasonic vibration on the strengthening area of ​​the workpiece 16 to be strengthened, and a strong acoustic cavitation phenomenon is generated at the focus, thereby forming high temperature, high pressure, micro jets, shock waves, etc. to produce an impact strengthening effect on the workpiece surface.

[0066] Finally, the focused ultrasonic transducer 12 completes the strengthening of the entire surface area of ​​the workpiece 16 according to the preset strengthening trajectory.

[0067] Example 2

[0068] like Fig. 9 As shown, in Figure 1 Based on the structure of the embodiment 1 shown, the number of focused ultrasonic transducers 12 is increased, and the installation method thereof can be symmetrical or multiple arrays, such as Fig. 9 It is a schematic diagram of the structure in which two focused ultrasonic transducers 12 are symmetrically installed.

[0069] Example 3

[0070] Will be like Figure 1 The multi-axis motion platform 1 in the embodiment 1 shown is replaced by Fig.10 The industrial robot shown can flexibly adjust its posture and controls the strengthening trajectory during the focused ultrasonic rotation surface strengthening process through the movement of the robotic arm.

[0071] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can make many improvements and changes without departing from the purpose of the present invention, which are all within the protection of the present invention.

Claims

1. An auto-focusing focused ultrasonic rotating surface strengthening device, comprising a multi-axis motion platform (1), an electric control system (2), an ultrasonic power supply (3), a dielectric tank (15) and a rotating strengthening system, characterized in that: The rotary strengthening system is composed of a rotary main shaft (4), a hollow conductive slip ring (5), a rotary mounting beam (6), a micro motor (7), a lead screw sliding mechanism (8), a motor mounting plate (9), a servo motor (10), a transducer fixture (11), a focused ultrasonic transducer (12), an underwater angle encoder (13) and a laser displacement sensor (14); The rotation strengthening system is installed on the main shaft of the multi-axis motion platform (1) through the upper end of the rotating main shaft (4); the electric control system (2) and the ultrasonic power supply (3) supply power to the rotation strengthening system and receive feedback information through the hollow conductive slip ring (5); the workpiece (16) is fixed at the bottom of the medium tank (15) and is located below the rotation strengthening system; The rotating main shaft (4) passes through the interior of the hollow conductive slip ring (5) and is fixedly connected to the rotor of the hollow conductive slip ring (5); the stator of the hollow conductive slip ring (5) is mounted on the multi-axis motion platform (1); The rotating mounting beam (6) is mounted on the end of the rotating main shaft (4), the lead screw sliding mechanism (8) is embedded in the rotating mounting beam (6), and a micro motor (7) is mounted on the back of the lead screw sliding mechanism (8); The transducer fixture (11) is connected to the lead screw sliding mechanism (8) via a hinge, the rotor of the servo motor (10) is fixedly connected to the transducer fixture (11), the stator of the servo motor (10) is fixedly connected to the lead screw sliding mechanism (8) via the motor mounting plate (9), and the focused ultrasonic transducer (12) is mounted on the transducer fixture (11); The underwater angle encoder (13) is installed at the tail of the servo motor (10), and the laser displacement sensor (14) is installed in the middle of the rotating mounting beam (6); The electric control system (2) measures and feeds back position information of the focused ultrasonic transducer (12) based on the underwater angle encoder (13) and the laser displacement sensor (14), and performs position fine-tuning to achieve automatic focusing; The focused ultrasonic transducer (12) realizes revolution around the central axis of the rotating main shaft (4) through the linkage of the rotating main shaft (4) and the rotating mounting beam (6); The micro motor (7), the servo motor (10), the underwater angle encoder (13) and the laser displacement sensor (14) are powered by the electric control system (2) through the hollow conductive slip ring (5) during rotation, and the focused ultrasonic transducer (12) is powered by the ultrasonic power supply (3) through the hollow conductive slip ring (5) during rotation.

2. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: The movement axis of the lead screw sliding mechanism (8) and the rotation center axis of the transducer fixture (11) around the hinge connection are on the same plane N, and the center axis of the rotating spindle (4) is perpendicular to the plane N; the intersection of the spherical surface of the focused ultrasonic transducer (12) and the connection structure is point A, the focal length f of the focused ultrasonic transducer (12), the distance between point A and the rotation center of the transducer fixture (11) around the hinge connection is a, the distance from the intersection of the center axis of the rotating spindle (4) and the plane N to the surface of the workpiece (16) is b, the distance between the rotation center axis of the transducer fixture (11) around the hinge and the center axis of the rotating spindle (4) is c, the rotation angle of the focused ultrasonic transducer (12) is θ, and the following conditions are satisfied: b 2 +c 2 =(a+f) 2 , where, c=(a+f)cosθ, b=(a+f)sinθ; The electric control system (2) performs fine adjustment of the position of the focused ultrasonic transducer (12) to achieve automatic focusing according to the rotation angle θ and the distance b measured and fed back by the underwater angle encoder (13) and the laser displacement sensor (14).

3. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: There is staggered-axis power transmission between the micro motor (7) and the lead screw sliding mechanism (8), and the transmission mechanism used is a staggered-axis gear pair or a worm gear pair, thereby achieving radial translation of the focused ultrasonic transducer (12).

4. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: The rotation angle θ of the focused ultrasonic transducer (12) is adjusted by the servo motor (10), thereby changing the incident angle of the sound wave of the focused ultrasonic surface reinforcement, and the incident angle is 30° to 60°.

5. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: The focused ultrasonic transducer (12) is one or more of an acoustic lens, a self-focused ultrasonic transducer, and an array transducer.

6. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: The ultrasonic power supply (3) generates high-frequency ultrasound of 200 KHz to 10 MHz.

7. The focused ultrasonic rotating surface strengthening device according to claim 1, characterized in that: The medium in the medium tank (15) is a liquid medium that can generate ultrasonic cavitation under high-frequency focused ultrasound or a suspension medium containing solid particles.

8. An auto-focusing focused ultrasonic rotating surface strengthening method, characterized in that: A focused ultrasonic rotating surface strengthening device as claimed in any one of claims 1 to 7, comprising: At the beginning of strengthening, the workpiece (16) is fixed at the bottom of the medium tank (15); the electric control system (2), the underwater angle encoder (13) and the laser displacement sensor (14) are started, and the electric control system (2) finely adjusts the position of the focused ultrasonic transducer (12) according to the rotation angle θ and the distance b measured and fed back by the underwater angle encoder (13) and the laser displacement sensor (14), so that the focus of the focused ultrasonic transducer (12) is simultaneously located at the solid-liquid interface between the workpiece (16) and the medium and on the central axis of the rotating spindle (4); Pouring a medium into the medium tank (15), wherein the medium in the medium tank (15) immerses the focused ultrasonic transducer (12); According to the geometric shape and size of the workpiece (16) to be strengthened, a strengthening trajectory is planned by means of the multi-axis motion platform (1); the multi-axis motion platform (1) is started, thereby driving the rotation spindle (4) to rotate, thereby driving the rotation strengthening system to rotate; The ultrasonic power supply (3) is started, and the rotating focused ultrasonic transducer (12) is powered through the hollow conductive slip ring (5); the focused ultrasonic transducer (12) focuses the ultrasonic vibration on the strengthening area of ​​the workpiece (16) to be strengthened, and a strong acoustic cavitation phenomenon is generated at the focus, thereby forming high temperature, high pressure, micro-jet, and shock wave, which produce an impact strengthening effect on the surface of the workpiece; the strengthening area at the focus is rotationally symmetrical, the strengthening impact function is a Gaussian-like function, and the strengthening area presents a Gaussian-like distribution. Different strengthening effects are achieved by controlling the dwell time of the focused ultrasonic transducer (12), and the focused ultrasonic transducer (12) completes the strengthening of all areas on the surface of the workpiece (16) according to a preset strengthening trajectory.

9. The focused ultrasonic rotation surface strengthening method according to claim 8, characterized in that: The strengthening area formed by the oblique focusing of the focused ultrasonic transducer (12) is in the shape of a crescent. The crescent-shaped strengthening area is transformed into a rotationally symmetrical Gaussian-like distribution shape by rotating around the central axis of the rotation main shaft (4). The impact function of the strengthening area is a Gaussian-like function. Then, through the trajectory motion of the multi-axis motion platform (1), large-area strengthening of the surface of the workpiece (16) is achieved.

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