Non-contact ultrasonic impact assisted scanning induction hardening device and method

Abstract

The application belongs to the technical field of metal component surface strengthening, and discloses a non-contact ultrasonic impact auxiliary scanning induction quenching device and method. The device comprises a machine tool body, a workpiece clamping and positioning system, a scanning carrier, a driving system, a high-frequency induction heating system, a non-contact ultrasonic impact system and a control system. The induction heating coil and the ultrasonic energy output component are fixed on the same scanning carrier through a rigid connection mechanism, so that the spatial positions of the two are constant and synchronous. The method comprises the following steps: after clamping and positioning the workpiece, setting process parameters and scanning paths, synchronously starting the heating and ultrasonic impact systems, driving the scanning carrier to move to realize the synergistic effect of scanning heating and non-contact ultrasonic impact, and then rapidly cooling to form a quenched strengthening layer. The application realizes the space-time depth synergy of the thermal-mechanical field, is suitable for complex curved surface components, improves the comprehensive performance of the strengthening layer, has high equipment durability and process automation degree, and is suitable for industrialized batch production.

Description

Technical Field

[0001] This invention belongs to the field of surface strengthening technology for metal components, specifically relating to a non-contact ultrasonic impact-assisted scanning induction hardening device and method. Background Technology

[0002] In the fields of aerospace, energy equipment, and large power machinery, a large number of core components (such as various types of turbine blades, variable cross-section crankshafts, and irregular molds) need to serve for a long time under high-speed erosion, cyclic alternating loads, and harsh corrosive environments. The edge areas of these components are stress concentration points and are extremely prone to fatigue damage, water erosion, and local performance degradation. Therefore, local strengthening of specific surfaces is the key to ensuring the reliability and service life of equipment.

[0003] High-frequency induction hardening technology is widely used in strengthening components with complex geometric features due to its advantages such as fast heating speed and precise local strengthening. For edge areas, existing technologies mostly employ scanning high-frequency induction hardening, achieving segmented heating by driving an induction coil to move along the component's trajectory. However, this type of technology mainly focuses on thermal field control and lacks means for synchronous and active strengthening of the microstructure during heat treatment. For example, patent document CN113544293A discloses a device using a U-shaped and straight section combined with an induction coil, which can achieve precise local heating of complex components such as turbine blades, but its function is essentially limited to temperature control and thermal field regulation. In actual scanning, for complex edges with large curvature changes and spatial orientation distortions (such as the edge of the last-stage turbine blade), it is difficult to maintain a constant relative gap and orientation between the induction coil and the workpiece, easily causing uneven local heating and large temperature fluctuations. This leads to uneven hardened layer depth and properties after quenching, and leaves large residual quenching stress, posing a high quality risk for thin-walled components.

[0004] Meanwhile, ultrasonic impact strengthening technology introduces dynamic stress disturbance through high-frequency vibration, which has significant advantages in improving residual stress distribution and refining surface microstructure. However, existing ultrasonic impact technologies generally use contact actuators and are mostly used as independent post-processing steps. Their action area is decoupled from the induction hardening heat treatment area in space and time, resulting in a lack of effective physical synergy between the two processes. For example, patent document CN103952531A discloses a device that uses a ring guide rail and a traveling mechanism to drive an ultrasonic impact head to perform high-frequency impacts on the workpiece surface. However, this is a typical "cold working" strengthening device, mainly used for stress relief at room temperature, and cannot be integrated synchronously with the quenching heating process. Furthermore, for precision components with complex curvatures, this type of contact strengthening method is prone to introducing scratches or collisions during the scanning process, and its mechanical responsiveness is poor, making it difficult to ensure that the impact strengthening area and the quenching hardened area are precisely overlapped in space and coordinated in depth.

[0005] In summary, existing technologies suffer from significant functional fragmentation and integration barriers: scanning induction hardening technology struggles to simultaneously achieve microstructure refinement and stress control during heat treatment; conventional contact ultrasonic impact, as an independent post-processing step, cannot achieve safe and efficient simultaneous integration during the quenching heating process due to its spatiotemporal decoupling and mechanical contact mode. Therefore, it is urgent to overcome these technological bottlenecks and provide a new strengthening principle that can achieve deep spatiotemporal synergy with scanning induction hardening. This principle would introduce the force field effect of high-frequency ultrasonic impact into the induction hardening thermal process in a non-contact manner, constructing an integrated device and method where the heating and strengthening regions are spatiotemporally consistent and the thermodynamic processes synergistic. This would allow for the simultaneous active control of microstructure and optimization of residual stress during quenching, resulting in a high-performance strengthened surface in a single process. Summary of the Invention

[0006] To address the problem of the separation and difficulty in effective coordination between scanning induction hardening and ultrasonic impact strengthening processes in existing technologies, this invention provides a non-contact ultrasonic impact-assisted scanning induction hardening device and method. The key to this invention lies in fixing the induction heating coil and the ultrasonic energy output component of the non-contact ultrasonic impact system onto the same scanning carrier via a rigid connection mechanism. This design ensures that during the scanning process, the active area of ​​the ultrasonic energy output component maintains a constant spatial relative position with the heating area of ​​the induction heating coil, thereby achieving synchronous operation of the two processes. This synchronization mechanism allows ultrasonic impact to be applied simultaneously at the high-temperature stage of the austenitizing phase transformation of the material. Through the synergistic effect of the thermal and force fields, the microstructure transformation and stress distribution during the hardening process are optimized, improving the surface strengthening effect and uniformity of complex components.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention is to provide a non-contact ultrasonic impact-assisted scanning induction hardening device, comprising:

[0009] Machine tool body;

[0010] A workpiece clamping and positioning system is installed on the machine tool body and is used to clamp the workpiece and adjust its spatial position and rotation posture.

[0011] The scanning carrier is movably mounted on the machine tool body;

[0012] A scanning carrier driving system is used to drive the scanning carrier to perform multi-degree-of-freedom motion relative to the workpiece;

[0013] A high-frequency induction heating system includes an induction heating coil mounted on the scanning carrier;

[0014] A non-contact ultrasonic impact system includes an ultrasonic energy output component mounted on the scanning carrier, used to apply ultrasonic impact to the surface of a workpiece in a non-contact manner;

[0015] The system is connected in communication with the workpiece clamping and positioning system, the scanning carrier driving system, the high-frequency induction heating system, and the non-contact ultrasonic impact system.

[0016] The scanning carrier includes a rigid connection mechanism, through which the induction heating coil and the ultrasonic energy output component are fixed to each other and maintain a constant spatial relative position. This ensures that when the scanning carrier driving system drives the scanning carrier to move, the working area of ​​the ultrasonic energy output component and the heating area of ​​the induction heating coil maintain a constant spatial positional relationship, thereby achieving synchronous follow-up of ultrasonic impact and induction heating.

[0017] According to an embodiment of the present invention, the workpiece clamping and positioning system includes:

[0018] A workpiece feeding and rotation mechanism is located at one end of the machine tool body, and a clamping assembly is installed at its output end. The clamping assembly is used to clamp one end of the workpiece.

[0019] A pneumatic clamping and coaxial rotation mechanism is provided at the other end of the machine tool body to provide pneumatic clamping and coaxial follow-up support for the other end of the workpiece.

[0020] The workpiece feeding and rotation mechanism is also used to drive the clamping assembly to move the workpiece it is clamping into or out of the workpiece processing area along the Y-axis, and to drive the workpiece to rotate around its own axis.

[0021] According to an embodiment of the present invention, the clamping assembly includes an embedded positioning surface that matches the shape of the clamped part of the workpiece and a clamping element, wherein the clamping element is a pneumatic clamping block or a hydraulic clamping block.

[0022] According to an embodiment of the present invention, the scanning carrier driving system includes an X-axis linear motion mechanism and a Z-axis linear motion mechanism. The X-axis linear motion mechanism is used to drive the scanning carrier to move along the X-axis direction, and the Z-axis linear motion mechanism is used to drive the scanning carrier to move along the Z-axis direction, so as to adjust the interaction distance between the induction heating coil and the ultrasonic energy output component and the part of the workpiece to be processed.

[0023] Wherein, the X-axis direction is the main scanning direction of the workpiece, the Z-axis direction is the height direction, and the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other.

[0024] According to an embodiment of the present invention, during operation, the interaction distance between the ultrasonic energy output component and the part of the workpiece to be processed is configured to be 0.5~5.0 mm.

[0025] According to an embodiment of the present invention, during operation, the interaction distance between the ultrasonic energy output component and the part of the workpiece to be processed is configured to be 1~3mm.

[0026] According to an embodiment of the present invention, during operation, the operating frequency of the non-contact ultrasonic shock system is configured to be 18kHz~30kHz.

[0027] According to an embodiment of the present invention, during operation, the operating frequency of the non-contact ultrasonic shock system is configured to be 20kHz~25kHz.

[0028] According to an embodiment of the present invention, the non-contact ultrasonic impact system further includes an ultrasonic transducer and an amplitude transformer, wherein the ultrasonic energy output component is an impact head assembly installed at the output end of the amplitude transformer.

[0029] A second aspect of the present invention provides a non-contact ultrasonic impact-assisted scanning induction hardening method, characterized in that it employs the aforementioned non-contact ultrasonic impact-assisted scanning induction hardening device and includes the following steps:

[0030] S1. The workpiece is clamped and positioned by the workpiece clamping and positioning system;

[0031] S2. Set the process parameters and scanning path through the control system;

[0032] S3. Activate the high-frequency induction heating system and the non-contact ultrasonic impact system;

[0033] S4. Control the scanning carrier driving system to drive the scanning carrier to move along a preset scanning path, so that the induction heating coil performs scanning heating on the workpiece surface. At the same time, the ultrasonic energy output component, which is spatially synchronized through the rigid connection mechanism, applies non-contact ultrasonic impact to the corresponding heating area. Under the synergistic effect of the synchronized induction heating and ultrasonic impact, the workpiece surface is strengthened.

[0034] S5. The workpiece is then rapidly cooled to form a hardened layer on the workpiece surface.

[0035] According to an embodiment of the present invention, in step S4, the surface of the workpiece is heated to 30~120°C above its austenitization termination temperature.

[0036] According to an embodiment of the present invention, in step S4, the surface of the workpiece is heated to 50-100°C above its austenitization termination temperature.

[0037] According to an embodiment of the present invention, in step S4, the scanning speed is 3.0 mm / s to 15.0 mm / s.

[0038] According to an embodiment of the present invention, in step S4, the scanning speed is 4.0 mm / s to 8.0 mm / s.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1. Achieved deep spatiotemporal synergy of the "thermal-mechanical" field: The non-contact ultrasonic impact-assisted scanning induction quenching device and method provided by this invention fixes the induction heating coil and the ultrasonic energy output component of the non-contact ultrasonic impact system on the same scanning carrier through a rigid connection mechanism. This ensures that the ultrasonic impact area and the induction heating area maintain a constant spatial relative position during the scanning process, achieving strict synchronous movement of the two processes. This design breaks through the barrier of spatiotemporal separation between induction quenching and ultrasonic impact strengthening in traditional processes, enabling the dynamic stress field of ultrasonic impact to deeply intervene in the phase transformation process of the material during the austenitizing high-temperature stage, thereby simultaneously achieving microstructure refinement and stress control during the quenching process.

[0041] 2. Solved the problem of strengthening complex curved surface components: The non-contact ultrasonic impact-assisted scanning induction hardening device and method provided by this invention adopts non-contact ultrasonic impact, fundamentally avoiding the scratching, collision risks, and poor follow-up problems that may be caused by traditional contact strengthening tools (such as impact heads and rollers) when scanning complex curvature and thin-edge components. The non-contact mode has better spatial attitude adaptability and can stably output energy to complex curved surfaces, making it particularly suitable for edge strengthening of precision components with large torsion and variable cross-section characteristics, such as steam turbine blades.

[0042] 3. Significantly improved overall performance of the reinforced layer: The non-contact ultrasonic impact-assisted scanning induction hardening device and method provided by this invention simultaneously applies ultrasonic impact, which effectively promotes the refinement of austenite grains and the uniformity of the phase transformation process by introducing high-frequency dynamic stress. As shown in Table 1, compared with traditional scanning induction hardening (Comparative Example 1), the method of this invention can obtain higher surface hardness, a deeper effective hardened layer, finer grain structure, and greater surface compressive stress, comprehensively improving the wear resistance, fatigue resistance, and service life of the workpiece surface.

[0043] 4. Improved process reliability and equipment durability: The non-contact mode isolates the high temperature generated by induction heating from the direct impact of ultrasonic impact actuators, avoiding wear, adhesion or failure of the tool head at high temperatures, and significantly improving the long-term working stability and reliability of the ultrasonic impact system in high-temperature collaborative working environments.

[0044] 5. Achieves automation and high-precision control: The entire device integrates a high-precision multi-axis motion system, induction heating system, non-contact ultrasonic impact system, and comprehensive control system. It can achieve fully automated operation according to preset process parameters and scanning paths, ensuring the consistency and repeatability of the strengthening process, and is suitable for industrial mass production. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of a non-contact ultrasonic impact-assisted scanning induction hardening device in one embodiment of this application.

[0046] Figure 2 for Figure 1 A schematic diagram of the embedded positioning surface of the clamping assembly (taking the clamping of the blade root of the last stage of a steam turbine as an example).

[0047] Figure 3 for Figure 1 A schematic diagram of the structure of the scanning carrier driving system.

[0048] Figure 4 for Figure 1 A schematic diagram of an induction heating coil and a non-contact ultrasonic impact system mounted on a scanning carrier.

[0049] In the diagram: 10 - Machine tool body;

[0050] 21-Workpiece feeding and rotation mechanism; 22-Clamping assembly; 221-Embedded positioning surface; 222-Clamping component; 223-Steam turbine last stage blade; 23-Pneumatic clamping and coaxial rotation mechanism;

[0051] 30 - Scanning carrier; 31 - Rigid connection mechanism;

[0052] 40 - Scanning carrier drive system; 41 - X-axis motion guide rail; 42 - Slider; 43 - Z-axis motion guide rail; 44 - Z-axis drive motor; 45 - Lead screw; 46 - Vertical slide table;

[0053] 50 - Induction heating coil;

[0054] 61-Ultrasonic fixing mechanism; 62-Ultrasonic clamping mechanism; 63-Ultrasonic transducer; 64-Amplitude rod; 65-Impact head assembly. Detailed Implementation

[0055] To facilitate understanding of the technical solution proposed by this invention to address the technical deficiencies in the prior art, the technical principles and specific embodiments of this invention will be described in detail below with reference to the accompanying drawings. This embodiment uses blade-like components with complex curvature and thin-edge characteristics (such as the last-stage blade of a steam turbine) as a specific application example; however, the application scope of this invention is not limited to this, and it is equally applicable to all types of engineering components that require scanning induction hardening and surface synergistic strengthening treatment.

[0056] The core of this invention lies in constructing a composite strengthening synergistic mechanism of high-frequency induction hardening and non-contact ultrasonic impact. Through research, the inventors discovered that this synergistic mechanism can effectively solve the technical problem of poor strengthening effect and easy damage in the edge area of ​​complex components.

[0057] In traditional scanning high-frequency induction hardening processes, a high-frequency alternating magnetic field induces eddy currents on the workpiece surface, causing instantaneous austenitization in the target area, and quenching is completed through self-cooling or forced cooling. However, for edge regions of components with complex curvature, thin edges, and variable spatial orientations, this process has significant inherent limitations: dynamic fluctuations in the gap between the induction heating coil and the workpiece, as well as real-time changes in the component's orientation, easily lead to uneven local temperature field distribution, which in turn seriously affects the uniformity of the phase transformation structure and the stability of the overall strengthening effect.

[0058] Meanwhile, traditional contact-based processes (such as rolling and shot peening) face significant challenges in the subsequent strengthening of such thin-walled edge components: contact mechanical forces easily cause plastic deformation and surface scratches at the workpiece edges, compromising the dimensional accuracy of the components; and under high-speed scanning conditions, contact tools struggle to maintain constant pressure contact with large twisted surfaces in real time, easily leading to interference and collisions. Furthermore, in the high-temperature environment of induction heating, contact tool heads are more prone to wear, adhesion, and other failures, severely restricting the long-term reliability of the "thermal-mechanical" synergistic process.

[0059] To address this, this invention introduces non-contact ultrasonic impact technology. The inventors discovered that this technology transfers energy through medium coupling, avoiding direct mechanical contact with the workpiece surface and fundamentally eliminating geometric damage caused by contact stress. It possesses excellent spatial adaptability and, compared to contact tools, can achieve stable energy output and support under complex curved surface conditions. Crucially, the non-contact mode effectively isolates the thermal impact of high-temperature environments on the reinforcing medium, significantly improving tool durability and ensuring the long-term stable operation of the composite process system.

[0060] Further research revealed that the high-frequency dynamic stress field introduced by non-contact ultrasonic impact can deeply influence the phase transformation behavior, dislocation migration, and evolution of residual stress fields on the material surface without physical contact. When the ultrasonic action area and the induction heating area are precisely overlapped in space and strictly synchronized in time, the dynamic stress introduced by the ultrasound will deeply participate in the entire process of material heating, phase transformation, and quenching. This synergistic effect not only effectively refines the surface grain structure but also significantly optimizes the distribution of residual stress, ultimately achieving a dual improvement in the depth, uniformity, and stability of the strengthening layer.

[0061] Based on the above principles, this invention, through structural integration design, integrates the non-contact ultrasonic impact system and the scanning induction heating system into a synchronously moving, unified motion unit. This design ensures that the ultrasonic action area and the induction heating area maintain spatial overlap and process coordination throughout the entire scanning stroke, thereby providing a highly efficient and stable composite surface strengthening technology solution for the edge regions of complex components.

[0062] 1.1 Non-contact ultrasonic impact-assisted scanning induction hardening device

[0063] Please see Figure 1 The present invention first provides a non-contact ultrasonic impact assisted scanning induction hardening device, which mainly includes a machine tool body 10, a workpiece clamping and positioning system, a scanning carrier 30, a scanning carrier driving system 40, a high-frequency induction heating system, a non-contact ultrasonic impact system, and a control system.

[0064] The machine tool body 10 serves as the supporting foundation for the entire device, and preferably employs a high-rigidity horizontal bed structure to ensure the stability of the equipment during dynamic scanning. To clearly describe the spatial relationships of the various moving parts, they are defined as follows: Figure 1 The coordinate system shown is a right-handed Cartesian coordinate system. The X-axis is the direction parallel to the main extension or scanning path of the workpiece (e.g., the last stage blade 223 of a steam turbine), and this direction is the main motion direction for scanning processing. The Z-axis is defined as the direction perpendicular to the worktable surface of the machine tool body 10 and pointing towards the workpiece; it is used to adjust the working distance between the processing head (induction heating coil 50 and impact head assembly 65) and the part of the workpiece to be processed. The Y-axis is defined as the direction perpendicular to both the X-axis and Z-axis and parallel to the workpiece feed direction; this direction is mainly used for workpiece loading, positioning, and lateral adjustment. The X-axis, Y-axis, and Z-axis are mutually perpendicular.

[0065] The workpiece clamping and positioning system is installed on the worktable of the machine tool body 10 to reliably clamp the workpiece and adjust its position and orientation during machining. Specifically, in conjunction with... Figure 1 and Figure 2The workpiece clamping and positioning system mainly includes a workpiece feeding and rotating mechanism 21 located at one end of the machine tool body 10, and a pneumatic clamping and coaxial rotating mechanism 23 located at the other end and opposite to the workpiece feeding and rotating mechanism 21. The output end of the workpiece feeding and rotating mechanism 21 is equipped with a clamping assembly 22 specifically designed for the workpiece (the last stage blade 223 of a steam turbine), used to firmly clamp one end of the workpiece (i.e., the blade root). This clamping assembly 22 can be customized according to the specific shape of the workpiece. Its core is an embedded positioning surface 221 that highly matches the shape of the clamped part (blade root profile) of the workpiece, and is equipped with a clamping element 222 (the clamping element 222 is a pneumatic clamping block or a hydraulic clamping block), which can achieve high repeatability positioning of the workpiece. It can also quickly clamp the workpiece, ensuring the efficiency and stability of the clamping process; the workpiece feeding and rotation mechanism 21 has two functions: first, it drives the clamping assembly 22 and the workpiece it clamps to move along the Y-axis, realizing the loading and unloading of the workpiece in and out of the processing area and the initial alignment; second, it drives the workpiece to rotate around its own axis (which can be defined as the C-axis), thereby flexibly changing the circumferential orientation of the workpiece to be processed, adapting to the needs of all-round scanning and strengthening of complex curvature components; the pneumatic clamping and coaxial rotation mechanism 23 works in conjunction with the workpiece feeding and rotation mechanism 21 to provide pneumatic clamping force to the other end of the workpiece (the last stage blade of the steam turbine 223) (i.e., the free end of the blade), and at the same time provides coaxial follow-up support when the workpiece rotates around the C-axis. The pneumatic clamping and coaxial rotation mechanism 23 can adapt to the clamping requirements of workpieces of different sizes by adjusting the pneumatic pressure. It can ensure the firmness of workpiece clamping and avoid workpiece deformation caused by excessive clamping force. At the same time, through coaxial follow-up support, it can effectively enhance the overall rigidity of workpiece during scanning, reduce vibration amplitude, avoid heating and impact position deviation caused by vibration, and ensure the accuracy of composite strengthening process.

[0066] See also Figure 1 The scanning carrier 30 is movably mounted on the machine tool body 10 and is made of high-strength aluminum alloy, combining lightweight and rigidity to prevent deformation during movement and ensure load-bearing stability; see [link to documentation]. Figure 1 , Figure 4 The scanning carrier 30 is integrated with a rigid connection mechanism 31. The rigid connection mechanism 31 is a component of the scanning carrier 30 and is used to fix the subsequent ultrasonic energy output component and the induction heating coil to each other, so that the two maintain a constant spatial relative position, providing a structural basis for the synchronous follow-up of subsequent ultrasonic impact and induction heating.

[0067] See Figure 1 , Figure 3The scanning carrier drive system 40 is connected to the scanning carrier 30 for driving the scanning carrier 30 to perform multi-degree-of-freedom motion relative to the workpiece. Specifically, it includes an X-axis linear motion mechanism and a Z-axis linear motion mechanism. The X-axis direction is the main scanning direction of the workpiece (the scanning speed can be adjusted according to process requirements to meet the precise scanning requirements of complex components), and the Z-axis direction is the height direction.

[0068] (1) X-axis linear motion mechanism: including X-axis motion guide rail 41 (arranged along the scanning direction) fixedly installed on the worktable of the machine tool body 10, slider 42 and servo ball screw drive assembly (not shown in the figure). Slider 42 can slide linearly along X-axis motion guide rail 41, driving scanning carrier 30 to reciprocate at a constant speed along X-axis direction, realizing scanning of the main direction of the workpiece surface to be processed. The scanning stroke can be flexibly adjusted according to the length of the workpiece to adapt to the scanning requirements of workpieces of different sizes.

[0069] (2) Z-axis linear motion mechanism: including Z-axis motion guide rail 43, Z-axis drive motor 44, lead screw 45 and vertical slide 46, which are installed on the slider 42 of the X-axis linear motion mechanism. It is used to drive the scanning carrier 30 to move up and down along the Z-axis direction, accurately adjust the action distance between the ultrasonic energy output component and the induction heating coil and the part of the workpiece to be processed, and adapt to the changes in the surface morphology and edge contour of the workpiece.

[0070] In some embodiments, the positioning accuracy of both the X-axis and Z-axis linear motion mechanisms can reach ±0.05mm.

[0071] See also Figure 1 The high-frequency induction heating system is used to perform scanning induction heating on the surface or edge area of ​​a workpiece. It includes an induction heating coil 50 and a matching high-frequency induction power supply (not shown in the figure). The induction heating coil 50 is mounted on the scanning carrier 30 via a rigid connection mechanism 31, maintaining a constant spatial relative position with the subsequent ultrasonic energy output component. In some embodiments, the induction heating coil 50 is made of copper tubing, and its shape is customized according to the contour of the part of the workpiece to be treated (such as the arc edge of the last stage blade of a steam turbine). With the gap adjustment of the Z-axis linear motion mechanism, the coil and the workpiece surface maintain a reasonable heating gap, ensuring heating efficiency and temperature uniformity. The high-frequency induction power supply is a solid-state high-frequency power supply, and the output power can be flexibly adjusted according to the workpiece material and strengthening requirements to achieve rapid austenitization of the workpiece surface.

[0072] See Figure 1 , Figure 4The non-contact ultrasonic impact system is used to apply ultrasonic impact to the surface of a workpiece in a non-contact manner. It includes an ultrasonic fixing mechanism 61, an ultrasonic clamping mechanism 62, an ultrasonic transducer 63, an amplitude transformer 64, and an impact head assembly 65 mounted on the output end of the amplitude transformer 64. The non-contact ultrasonic impact system is mounted on the scanning carrier 30 via a rigid connection mechanism 31, maintaining a constant spatial relative position with the induction heating coil 50. The ultrasonic fixing mechanism 61 serves as the overall mounting base for the non-contact ultrasonic impact system, fixedly connected to the rigid connection mechanism 31 of the scanning carrier 30, ensuring reliable assembly of the entire ultrasonic impact system with the scanning carrier 30 and providing stable mounting support for subsequent components. The ultrasonic clamping mechanism 62 is mounted on the ultrasonic fixing mechanism 61 and is used to clamp and fix the ultrasonic transducer 63. The ultrasonic transducer 63 and the amplitude transformer 64 are aligned to ensure coaxiality and prevent swaying during vibration transmission, thus ensuring efficient transmission of ultrasonic energy. The ultrasonic clamping mechanism 62 can fine-tune the clamping position according to actual assembly requirements to accommodate ultrasonic transducers 63 and amplitude transformers 64 of different specifications. The ultrasonic transducer 63 is a piezoelectric transducer, electrically connected to the ultrasonic generator (not shown in the figure), which can convert high-frequency electrical signals into mechanical vibrations of the same frequency, providing a vibration source for the entire ultrasonic impact system. The input end of the amplitude transformer 64 is fixedly connected to the output end of the ultrasonic transducer 63, and the other end is assembled with the impact head assembly 65. Through its variable cross-section structure design, it amplifies the mechanical vibration transmitted by the ultrasonic transducer 63, increases the vibration amplitude, and ensures that the impact head assembly 65 has sufficient ultrasonic impact energy to meet the process requirements of workpiece surface strengthening.

[0073] The impact head assembly 65 is integrally machined from high-temperature resistant ceramic material, possessing excellent wear resistance and thermal stability. It can effectively resist the high-temperature radiation of the induction heating area, avoiding deformation, wear, or adhesion to the workpiece at high temperatures. Its output end face is an arc-shaped structure adapted to the curvature of the workpiece surface, ensuring that the ultrasonic impact energy is uniformly applied to the workpiece to be treated. The impact head assembly 65 maintains a non-contact state with the workpiece to be treated, and the interaction distance between the two during operation is configured to be 0.5~5.0mm, preferably 1~3mm, and more preferably 2.0mm. Using air as the energy coupling medium, the amplified high-frequency mechanical vibration is transmitted to the workpiece surface in the form of shock waves. Without contacting the workpiece or causing surface scratches or thin-edge deformation, a periodic dynamic stress field is introduced into the material surface, interfering with the phase transformation behavior and dislocation movement of the material.

[0074] It should be noted that in the present invention, the "acting distance between the induction heating coil and the workpiece to be processed" and the "acting distance between the ultrasonic energy output component and the workpiece to be processed" have the same definition: both refer to the vertical distance from the effective working surface of the coil or the working end face of the ultrasonic energy output component (such as the impact head assembly 65) along the Z-axis direction (i.e., the normal direction perpendicular to the local surface of the workpiece to be processed point) to the geometric surface of the workpiece at this point during operation. These two distances are dynamically adjusted and controlled synergistically or independently through the same set of Z-axis linear motion mechanisms to be maintained within the optimal ranges required by their respective processes, thereby jointly ensuring the stable and synergistic coupling of the induction heat field and the ultrasonic force field and achieving uniform strengthening.

[0075] The overall operating frequency of the non-contact ultrasonic impact system (i.e., the operating frequency of the impact head assembly 65) is configured to be 18 kHz to 30 kHz, preferably 20 kHz to 25 kHz, and more preferably 23 kHz; the ultrasonic impact within this frequency range can effectively cooperate with the process rhythm of induction heating, form a synergistic effect with induction heating, refine the grain structure of the workpiece and optimize the residual stress distribution during the austenitization and cooling phase transformation processes on the surface layer of the workpiece, and improve the uniformity and stability of the quenching strengthening layer. Moreover, since the entire non-contact ultrasonic impact system maintains a constant spatial relative position with the induction heating coil 50 through the rigid connection mechanism 31, during the movement of the scanning carrier 30, the ultrasonic action area of the impact head assembly 65 and the heating area of the induction heating coil 50 always accurately correspond, achieving synchronous follow-up of ultrasonic impact and induction heating, and ensuring a high degree of unity of "thermal-mechanical" synergistic strengthening in space and time.

[0076] To achieve the automatic control of the entire device, the non-contact ultrasonic impact-assisted scanning induction quenching device is equipped with a control system (not shown in the figure). This control system uses a PLC controller as the core control unit, and is electrically communicatively connected to the workpiece clamping and positioning system, the scanning carrier drive system 40, the high-frequency induction heating system, and the non-contact ultrasonic impact system respectively. At the same time, it accesses the sensor components supporting each system to form a full-process closed-loop control system, coordinating and controlling each subsystem to work synergistically according to a preset program.

[0077] 1.2 Non-contact ultrasonic impact-assisted scanning induction quenching method

[0078] The present application further provides a non-contact ultrasonic impact-assisted scanning induction quenching method based on the non-contact ultrasonic impact-assisted scanning induction quenching device in 1.1 (taking the edge strengthening of the last-stage blade 223 of a steam turbine as an example). Through full-process automatic control, the spatio-temporal synchronization and synergy of scanning induction heating and non-contact ultrasonic impact are achieved, and the surface composite strengthening of components with complex curvature and thin edges is completed. The specific steps are as follows:

[0079] S1. Workpiece clamping and positioning: The workpiece clamping and positioning system reliably clamps the turbine's last-stage blade 223 and precisely adjusts its spatial position and rotational attitude. The root portion of the turbine's last-stage blade 223 is placed close to the embedded positioning surface 221 of the clamping assembly 22. A preset clamping force is applied by the clamping component 222 to achieve high repeatability clamping and positioning of the blade root. The pneumatic clamping and coaxial rotation mechanism 23 at the other end of the machine tool body 10 is activated to apply a suitable pneumatic clamping force to the other end of the turbine's last-stage blade 223. The dynamic clamping force is used to achieve reliable coaxial support at both ends of the turbine's last stage blade 223 to enhance its processing rigidity. Then, the workpiece feeding and rotation mechanism 21 is controlled to drive the clamping assembly 22 and the turbine's last stage blade 223 to translate along the Y-axis, moving the turbine's last stage blade 223 into the processing area and completing the initial alignment. At the same time, the turbine's last stage blade 223 is driven to rotate around its own axis, adjusting its surface to be processed to a preset position that precisely corresponds to the induction heating coil 50 and the impact head assembly 65, completing the attitude calibration before processing.

[0080] S2. Process Parameters and Scanning Path Setting: The control system completes the numerical setting of all process parameters and the planning of the scanning path. The interaction distance between the impact head assembly 65 and the part to be treated on the last stage blade 223 of the turbine is set in this step. All parameters are stored in the process parameter library of the control system to provide a benchmark for automated operation. The working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is set to 18kHz~30kHz according to process requirements, preferably 20kHz~25kHz, and more preferably 23kHz. At the same time, the interaction distance between the impact head assembly and the part to be treated on the last stage blade 223 of the turbine is precisely set to 0.5~5.0mm, preferably 1~3mm, and more preferably 2mm, to ensure effective transmission of ultrasonic energy and no risk of contact damage. The output power of the high-frequency induction heating system is set according to the workpiece material, and the target heating temperature of the workpiece surface is determined to be higher than the austenitization temperature of its material. The termination temperature is 30~120℃, preferably 50~100℃ higher than the austenitizing termination temperature of the material (taking 1Cr12Ni3Mo2VN martensitic stainless steel, a commonly used material for turbine last-stage blades, as an example (Ac3 is calculated at approximately 930℃), its surface heating target temperature is 960~1050℃, preferably 980~1030℃, and more preferably 1000℃); the scanning speed of the scanning carrier drive system is set to 3.0mm / s~15.0mm / s, preferably 4.0mm / s~8.0mm / s, and the linear scanning path of the scanning carrier along the X-axis is planned so that the linear X-axis path matches the processing trajectory of the edge / curved surface to be processed of the turbine last-stage blade 223 along the X-axis direction. At the same time, auxiliary parameters such as the rotation angle of the turbine last-stage blade 223 around its own axis, the pneumatic clamping and the pneumatic clamping force of the coaxial rotation mechanism 23 are set to ensure that the turbine last-stage blade 223 has a stable posture during the scanning process;

[0081] S3. Start the high-frequency induction heating system and the non-contact ultrasonic impact system: The control system issues a start command to simultaneously start the high-frequency induction heating system and the non-contact ultrasonic impact system, completing preheating and parameter stabilization; after the high-frequency induction heating system starts, the high-frequency induction power supply supplies power to the induction heating coil 50, and the induction heating coil 50 generates a stable high-frequency alternating electromagnetic field, entering the heating-ready working state; after the non-contact ultrasonic impact system starts, the ultrasonic generator outputs a high-frequency electrical signal to the ultrasonic transducer 63, which is converted by the ultrasonic transducer 63 and amplified by the amplitude transformer 64, driving the impact head assembly 65 to generate a stable preset frequency high-frequency vibration, entering the impact-ready working state; the control system monitors the operating parameters of the two systems in real time through various sensors until the heating power and ultrasonic vibration frequency reach the preset stable values, completing the system preparation before processing;

[0082] S4. Synchronous Heating and Non-Contact Ultrasonic Impact: The control system controls the scanning carrier drive system 40, driving the scanning carrier 30 to move at a constant speed along a preset X-axis linear scanning path. Simultaneously, the Z-axis linear motion mechanism adjusts the height of the scanning carrier 30 in real time according to the curvature of the surface to be treated on the turbine's last-stage blade 223, ensuring a stable working distance between the impact head assembly 65 and the part of the turbine's last-stage blade 223 to be treated, and between the induction heating coil 50 and the part of the turbine's last-stage blade 223 to be treated. During the scanning process, the induction heating coil 50 moves synchronously with the scanning carrier 30, continuously scanning and heating the surface of the turbine's last-stage blade 223, thus heating the surface of the turbine's last-stage blade 223. 3. The surface layer is rapidly heated to the preset austenitizing temperature; at the same time, the impact head assembly 65 moves synchronously with the scanning carrier 30, continuously applying non-contact ultrasonic impact to the corresponding heating area of ​​the turbine's last stage blade 223, forming a synergistic strengthening effect with induction heating; if it is necessary to achieve all-round strengthening of the turbine's last stage blade 223, the workpiece feeding and rotation mechanism 21 drives the turbine's last stage blade 223 to rotate around its own axis to a preset angle, and the pneumatic clamping and coaxial rotation mechanism 23 synchronously follows and supports, so that the parts to be processed at different circumferential positions of the turbine's last stage blade 223 enter the scanning area in sequence, and with the X-axis linear motion of the scanning carrier 30, the composite strengthening of the entire surface of the workpiece is completed;

[0083] S5. Rapid cooling to form a hardened layer: After the scanning carrier 30 completes the preset X-axis linear scanning path, the control system controls the high-frequency induction heating system and the non-contact ultrasonic impact system to stop working synchronously, and immediately cools the turbine last stage blade 223 with an appropriate rapid cooling method (such as air cooling), so that the surface of the turbine last stage blade 223 is rapidly cooled down, and the phase transformation from austenite to martensite is completed, and finally a uniform and dense hardened layer is formed on the surface of the workpiece.

[0084] S6. Workpiece unloading: After the turbine last-stage blade 223 has completely cooled and the quenched and strengthened layer has formed, the control system controls the workpiece clamping and positioning system to operate in sequence. First, the pneumatic clamping and coaxial rotation mechanism 23 releases the clamping force on the turbine last-stage blade 223, then the clamping member 222 of the clamping assembly 22 is released. Subsequently, the workpiece feeding and rotation mechanism 21 is driven to move the turbine last-stage blade 223 out of the processing area along the Y-axis direction. The turbine last-stage blade 223 is then removed, thus completing the entire non-contact ultrasonic impact assisted scanning induction quenching process.

[0085] The present invention will be described in detail below with reference to specific embodiments, but this does not limit the present invention.

[0086] The following embodiments involve the following testing methods:

[0087] Surface hardness testing: Performed according to GB / T 230.1-2018 "Metallic materials, Rockwell hardness test - Part 1: Test method". Testing equipment and parameters: A digital Rockwell hardness tester (e.g., HR-150A) was used; a diamond cone indenter was selected, with a scale of HRC, and a total test force of 1471 N (150 kgf) was applied. Sampling and measurement method: On the surface of the machined area after scanning induction hardening, five test points were evenly selected along the X-axis scanning direction for measurement. The highest and lowest values ​​were discarded, and the average value was taken as the final surface hardness of the sample group to ensure data reliability.

[0088] Surface residual stress testing: Performed according to GB / T 7704-2017 "Non-destructive Testing - X-ray Stress Measurement Method". Testing equipment and parameters: An X-ray residual stress analyzer was used; for martensitic stainless steel, Cr-Kα rays were selected as the target, the martensitic (211) crystal plane was chosen as the diffraction plane, and the sin oscillation method was adopted. 2 (ψ method). Sampling and measurement method: To verify the effect of non-contact ultrasonic shock on improving the stress field, three points were scanned and measured in the center zone of the main ultrasonic wave action area, and the average value was taken (negative values ​​were recorded as compressive stress, and positive values ​​were recorded as tensile stress).

[0089] Average grain size characterization: Refer to GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals". Test equipment and parameters: Microstructure observation was performed using an optical microscope (OM) or scanning electron microscope (SEM). Sampling and measurement methods: Cross-sectional samples were cut along the normal direction perpendicular to the scanning surface. After grinding and polishing, the samples were etched with a ferric chloride hydrochloric acid aqueous solution (e.g., 5 g FeCl3 + 50 mL HCl + 100 mL H2O) to clearly expose the original austenite grain boundaries. The intercept method (section method) was used to statistically analyze the average intercept length of the original austenite grains within the field of view at 500x magnification, and then converted into the average grain size.

[0090] Determination of Effective Hardened Layer Depth: Performed according to GB / T 5617-2025 "Determination of Hardened Layer Depth on Steel Parts Surface". Measurement Method: The hardness method (micro Vickers hardness gradient method) is used. The quenched sample is cut along its cross-section, and after mounting, grinding, polishing, and etching, it is measured using a micro Vickers hardness tester (test force 4.903 N, HV0.5). Starting from the quenched surface, measurements are taken point by point along a direction perpendicular to the surface, with a spacing of 0.1 mm to 0.2 mm. At least 3 points are measured at each depth, and the average value is taken. The depth corresponding to the specified limit hardness is taken as the effective hardened layer depth. Measurements are taken point by point from the sample surface towards the center until the hardness value drops to the limit hardness; the vertical distance from that point to the surface is the effective hardened layer depth. At least 3 different paths are measured for each sample, and the average value is taken as the final effective hardened layer depth (the limit hardness is determined according to the minimum surface hardness specified in the part's technical conditions: after converting the minimum surface hardness to Vickers hardness, 80% of it is taken as the limit hardness).

[0091] Example 1

[0092] This embodiment employs the non-contact ultrasonic impact-assisted scanning induction hardening device (section 1.1) and the non-contact ultrasonic impact-assisted scanning induction hardening method (section 1.2) to perform surface composite hardening on the 223 last-stage turbine blade (material: 1Cr12Ni3Mo2VN martensitic stainless steel, Ac3 approximately 930℃; the area to be strengthened is the blade edge, which is a complex curvature, thin-edge component). The specific implementation process strictly follows steps S1 to S6 of the non-contact ultrasonic impact-assisted scanning induction hardening method (section 1.2). Its specific implementation hinges on the precise setting of process parameters, with the following core parameters defined:

[0093] The operating frequency of the non-contact ultrasonic impact system (the operating frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the target heating temperature of the surface of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s.

[0094] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0095] Example 2

[0096] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 18kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0097] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0098] Example 3

[0099] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 20kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0100] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0101] Example 4

[0102] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 25kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0103] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0104] Example 5

[0105] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 30kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0106] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0107] Example 6

[0108] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 0.5mm, the target heating temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0109] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0110] Example 7

[0111] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 1.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0112] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0113] Example 8

[0114] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 3.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0115] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0116] Example 9

[0117] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 5.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0118] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0119] Example 10

[0120] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 960℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0121] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0122] Example 11

[0123] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 980℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0124] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0125] Example 12

[0126] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1030℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0127] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0128] Example 13

[0129] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1050℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0130] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0131] Example 14

[0132] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 3.0mm / s;

[0133] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0134] Example 15

[0135] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the target heating temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 4.0mm / s;

[0136] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0137] Example 16

[0138] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 8.0mm / s;

[0139] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0140] Example 17

[0141] The non-contact ultrasonic impact-assisted scanning induction hardening method in this embodiment is basically the same as that in Embodiment 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 15.0mm / s;

[0142] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0143] Comparative Example 1

[0144] This comparative example uses the traditional scanning induction hardening method (without ultrasonic assistance) to perform surface composite hardening on the last stage blade of a steam turbine (material is 1Cr12Ni3Mo2VN martensitic stainless steel, Ac3 is about 930℃, the part to be strengthened is the blade edge, which is a complex curvature and thin-edge component). The target heating temperature of the 223 surface layer of the last stage blade of the steam turbine is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s.

[0145] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0146] Comparative Example 2

[0147] The non-contact ultrasonic impact-assisted scanning induction hardening method in this comparative example is basically the same as that in Example 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 6.0mm, the target heating temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0148] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0149] Comparative Example 3

[0150] The non-contact ultrasonic impact-assisted scanning induction hardening method in this comparative example is basically the same as that in Example 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 25.0mm / s;

[0151] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0152] Comparative Example 4

[0153] The non-contact ultrasonic impact-assisted scanning induction hardening method in this comparative example is basically the same as that in Example 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 15kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the target heating temperature of the surface layer of the turbine last stage blade 223 is 1000℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0154] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0155] Comparative Example 5

[0156] The non-contact ultrasonic impact-assisted scanning induction hardening method in this comparative example is basically the same as that in Example 1, except that: the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is 23kHz, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is 2.0mm, the heating target temperature of the surface layer of the turbine last stage blade 223 is 930℃, and the scanning speed of the scanning carrier drive system along the X-axis is set to 5.0mm / s;

[0157] After the material was cut, the surface hardness, surface residual stress, effective hardened layer depth and average grain size of the last stage blade 223 of the steam turbine were measured, as shown in Table 1.

[0158] Table 1. Quenching strengthening effect of Examples 1-17 and Comparative Examples 1-5

[0159]

[0160] Hereinafter, the working frequency of the non-contact ultrasonic impact system (the working frequency of the impact head assembly 65) is referred to as the ultrasonic frequency, the interaction distance between the impact head assembly 65 and the part to be treated of the turbine last stage blade 223 is referred to as the non-contact interaction distance, the heating target temperature of the surface of the turbine last stage blade 223 is referred to as the heating temperature, and the scanning speed of the scanning carrier drive system along the X-axis is referred to as the scanning speed.

[0161] Based on the data in Table 1, the specific analysis is as follows:

[0162] 1. Comparison of the core solution of this invention with traditional processes: A direct comparison is made between the solution of this invention using optimal parameters (Example 1: ultrasonic frequency 23kHz, non-contact action distance 2.0mm, heating temperature 1000℃, scanning speed 5.0mm / s) and traditional scanning induction hardening without ultrasonic assistance (Comparative Example 1). Data shows that the solution of this invention achieves significant improvements in all aspects: surface hardness increases from HRC52 to HRC57; surface residual compressive stress increases significantly from 380 MPa to 505 MPa; effective hardened layer depth increases from 1.20 mm to 1.36 mm; and the average grain size is refined from 8.5 μm to 6.4 μm. This comprehensive optimization of four indicators fully demonstrates that the spatiotemporal synergy of non-contact ultrasonic impact and induction heating can effectively refine the microstructure, introduce greater compressive stress, and increase the hardened layer depth, resulting in a comprehensive strengthening effect far exceeding that of a single hot working process.

[0163] 2. Impact analysis of key process parameters:

[0164] To explore the process window, the experiment systematically varied four core parameters: ultrasonic frequency, non-contact interaction distance, heating temperature, and scanning speed. The results revealed their significant impact on the enhancement effect and clarified the process window for each parameter.

[0165] a. Effect of Ultrasonic Frequency (Examples 1-5): The data in Table 1 show that ultrasonic frequencies in the range of 18-30 kHz produce a significant synergistic strengthening effect, which is significantly better than the traditional process without ultrasonic assistance (Comparative Example 1). Especially in the range of 20 kHz-25 kHz, the strengthening effect (such as surface hardness and compressive stress level) reaches a better level, with 23 kHz (Example 1) showing the best overall performance. Although frequencies below 20 kHz (e.g., 18 kHz, Example 2) or above 25 kHz (e.g., 30 kHz, Example 5) are still effective, all indicators show an observable decrease. When the ultrasonic frequency drops to 15 kHz (Comparative Example 4), the strengthening effect is no significantly different from that of Comparative Example 1 (without ultrasonic assistance), indicating that the synergistic strengthening effect of ultrasonic impact is basically ineffective at this frequency. This shows that this preferred frequency range (20 kHz-25 kHz) can achieve optimal coupling between the dynamic stress field and the thermal process.

[0166] b. Effect of non-contact interaction distance (Examples 1, Examples 6-9): The non-contact interaction distance is crucial for ensuring effective ultrasonic energy transfer. The data in Table 1 show that the process can be effectively carried out within a non-contact interaction distance of 0.5-5.0 mm. However, to obtain a stable and excellent enhancement effect, the non-contact interaction distance should be controlled within a better range of 1.0-3.0 mm. Within this range, the ultrasonic energy transfer efficiency is high and stable. 2.0 mm (Example 1) is the optimal distance. Distances less than 1.0 mm (e.g., 0.5 mm, Example 6) or greater than 3.0 mm (e.g., 5.0 mm, Example 9) will lead to performance degradation. When the distance increases to 6.0 mm (Comparative Example 2), the synergistic effect is significantly weakened.

[0167] c. Effect of heating temperature (Examples 1, Examples 10-13): The heating temperature must ensure that the material undergoes sufficient austenitization, which is the basis for the subsequent ultrasonic synergistic effect. The data in Table 1 show that the heating temperature can be set in the range of 30-120°C above the material's austenitization termination temperature. A temperature window of 50-100°C above the material's austenitization termination temperature (taking 1Cr12Ni3Mo2VN martensitic stainless steel, a commonly used material for 223 turbine last-stage blades, as an example, where the Ac3 of 1Cr12Ni3Mo2VN martensitic stainless steel is about 930°C, i.e., 980-1030°C) is the preferred temperature window for producing excellent results, with 1000°C (Example 1) showing the best performance. Insufficient temperature (such as heating only to the Ac3 point, Comparative Example 5) will lead to incomplete austenitization and the worst performance in all indicators. Excessive temperature may lead to coarsening of the microstructure, which is not conducive to performance improvement.

[0168] d. Effect of Scanning Speed ​​(Examples 1, Examples 14-17): Scanning speed determines the duration of heat and force interaction within a unit area. Data in Table 1 shows that the process can be implemented within a test speed range of 3.0-15.0 mm / s. However, to ensure sufficient "thermal-mechanical" synergy, the scanning speed should ideally be controlled within the range of 4.0 mm / s to 8.0 mm / s, where the heating and ultrasonic interaction times are balanced. 5.0 mm / s (Example 1) is the optimal speed. Speeds below 4.0 mm / s (e.g., 3.0 mm / s, Example 14) or above 8.0 mm / s (e.g., 15.0 mm / s, Example 17) will cause performance degradation. When the speed is too fast, reaching 25.0 mm / s (Comparative Example 3), the interaction time is severely insufficient, the synergistic effect is almost impossible to establish, and the enhancement effect is significantly deteriorated.

[0169] 3. Parameter Boundary Verification: The enhancement effects of Comparative Examples 2-5 are significantly worse than those of the embodiments within the preferred range of this invention, and are close to or worse than those of the conventional process (Comparative Example 1). This demonstrates from the opposite perspective that the parameter range defined by this invention is a necessary boundary condition for achieving a significant synergistic enhancement effect. If the parameters exceed this range, the advantages of this invention will be weakened or even disappear.

[0170] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A non-contact ultrasonic impact-assisted scanning induction hardening method employing a non-contact ultrasonic impact-assisted scanning induction hardening device, characterized in that, The non-contact ultrasonic impact-assisted scanning induction hardening device includes: Machine tool body; A workpiece clamping and positioning system is installed on the machine tool body and is used to clamp the workpiece and adjust its spatial position and rotation posture. The scanning carrier is movably mounted on the machine tool body; A scanning carrier driving system is used to drive the scanning carrier to perform multi-degree-of-freedom motion relative to the workpiece; The high-frequency induction heating system includes an induction heating coil mounted on the scanning carrier; the high-frequency induction heating system is used to heat the surface layer of the workpiece to 30~120°C above its austenitization termination temperature, so as to achieve a high-temperature austenitization phase transformation of the workpiece surface layer. The non-contact ultrasonic impact system includes an ultrasonic energy output component mounted on the scanning carrier. The ultrasonic energy output component is an impact head assembly made of high-temperature resistant ceramic material. It uses air as the energy coupling medium and maintains an action distance of 0.5~5.0mm between itself and the part of the workpiece to be treated. It applies non-contact ultrasonic impact to the surface of the workpiece during the austenitization phase transformation stage of the workpiece. The system is connected in communication with the workpiece clamping and positioning system, the scanning carrier driving system, the high-frequency induction heating system, and the non-contact ultrasonic impact system. The scanning carrier includes a rigid connection mechanism. The induction heating coil and the ultrasonic energy output component are fixed to each other through the rigid connection mechanism and maintain a constant spatial relative position. This ensures that when the scanning carrier driving system drives the scanning carrier to move, the working area of ​​the ultrasonic energy output component and the heating area of ​​the induction heating coil maintain a constant spatial positional relationship, thereby achieving synchronous follow-up of ultrasonic impact and induction heating. Includes the following steps: S1. The workpiece is clamped and positioned by the workpiece clamping and positioning system; S2. Set the process parameters and scanning path through the control system; S3. Activate the high-frequency induction heating system and the non-contact ultrasonic impact system; S4. Control the scanning carrier driving system to drive the scanning carrier to move along a preset scanning path, so that the induction heating coil performs scanning heating on the workpiece surface. At the same time, the ultrasonic energy output component, which is spatially synchronized through the rigid connection mechanism, applies non-contact ultrasonic impact to the corresponding heating area. Under the synergistic effect of synchronized induction heating and ultrasonic impact, the workpiece surface is strengthened. S5. The workpiece is then rapidly cooled to form a hardened layer on the workpiece surface.

2. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 1, characterized in that, The workpiece clamping and positioning system includes: A workpiece feeding and rotation mechanism is located at one end of the machine tool body, and a clamping assembly is installed at its output end. The clamping assembly is used to clamp one end of the workpiece. A pneumatic clamping and coaxial rotation mechanism is provided at the other end of the machine tool body to provide pneumatic clamping and coaxial follow-up support for the other end of the workpiece. The workpiece feeding and rotation mechanism is also used to drive the clamping assembly to move the workpiece it is clamping into or out of the workpiece processing area along the Y-axis, and to drive the workpiece to rotate around its own axis.

3. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 2, characterized in that, The clamping assembly includes an embedded positioning surface that matches the shape of the part of the workpiece being clamped and a clamping component, wherein the clamping component is a pneumatic clamping block or a hydraulic clamping block.

4. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 2, characterized in that, The scanning carrier driving system includes an X-axis linear motion mechanism and a Z-axis linear motion mechanism. The X-axis linear motion mechanism is used to drive the scanning carrier to move along the X-axis direction, and the Z-axis linear motion mechanism is used to drive the scanning carrier to move along the Z-axis direction, so as to adjust the interaction distance between the induction heating coil and the ultrasonic energy output component and the part of the workpiece to be processed. Wherein, the X-axis direction is the scanning direction of the workpiece, the Z-axis direction is the height direction, and the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other.

5. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 4, characterized in that, During operation, the interaction distance between the ultrasonic energy output component and the part of the workpiece to be processed is configured to be 0.5~5.0mm.

6. The non-contact ultrasonic impact-assisted scanning induction hardening method using a non-contact ultrasonic impact-assisted scanning induction hardening device according to claim 1, characterized in that, During operation, the working frequency of the non-contact ultrasonic impact system is configured to be 18kHz~30kHz.

7. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 1, characterized in that, The non-contact ultrasonic impact system also includes an ultrasonic transducer and an amplitude transformer, wherein the ultrasonic energy output component is an impact head assembly installed at the output end of the amplitude transformer.

8. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 1, characterized in that, In step S4, the surface of the workpiece is heated to 30-120°C above its austenitization termination temperature.

9. The non-contact ultrasonic impact assisted scanning induction hardening method using a non-contact ultrasonic impact assisted scanning induction hardening device according to claim 1, characterized in that, In step S4, the scanning speed is 3.0 mm / s to 15.0 mm / s.

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