Ultrasonic shot peening surface strengthening device and method

Abstract

An ultrasonic shot peening surface strengthening device comprises an ultrasonic shot peening system and a pair of induction coils, the induction coils are coaxially arranged, and a machining cabin of the ultrasonic shot peening system is arranged on the axis between the two induction coils and surrounds the interior of a cylindrical surface defined by the two induction coils as the ends. According to the device, electromagnetic pulses can be applied to the to-be-machined part while super shot peening is carried out, induced current is formed on the surface of the to-be-machined part, and the depth and quality of shot peening strengthening are improved through cooperation of the electromagnetic effect. The invention further provides an ultrasonic shot peening surface strengthening method.

Description

Technical Field

[0001] The invention belongs to the field of metal processing, and in particular relates to an ultrasonic shot peening surface strengthening device and method. Background Art

[0002] Shot peening is an effective technical means for surface modification and forming, and is widely used in surface strengthening treatment of metal materials. In the manufacturing process of aircraft engines, shot peening treatment of the surface of parts can effectively improve the fatigue durability of parts and increase the service life of structural parts. However, the impact velocity distribution of traditional pneumatic shot peening varies greatly, the strengthening effect is uneven and it is easy to cause surface damage; while ultrasonic shot peening can easily make the surface of the material quickly reach the plastic deformation limit, which makes it easy to induce surface defects on the one hand if the strength of the surface strengthening treatment is enhanced by increasing the shot peening intensity, and on the other hand, the rapid hardening of the material surface hinders the deepening of the plastic deformation range, resulting in insufficient residual compressive stress distribution depth, so that key parts such as aircraft engines are prone to residual stress release under long-term service conditions, resulting in the decline of fatigue resistance and damage tolerance, which has an adverse effect on service life and service safety. Therefore, providing a shot peening device that can increase the residual compressive stress and its distribution depth has a high practical value for improving the surface strengthening effect of parts. Summary of the invention

[0003] The object of the present invention is to provide an ultrasonic shot peening surface strengthening device, which can improve the residual compressive stress layer formed by shot peening and its distribution depth. The present invention also provides an ultrasonic shot peening surface strengthening method.

[0004] According to an embodiment of one aspect of the present invention, there is provided an ultrasonic shot peening surface strengthening device, comprising a processing chamber and an ultrasonic oscillating device for ultrasonic shot peening strengthening, and also comprising a pair of induction coils, wherein the pair of induction coils are coaxially arranged, and the processing chamber is arranged on the axis between the pair of induction coils, so that the processing chamber is surrounded by a cylindrical surface formed by the pair of induction coils as ends.

[0005] By using this device, electromagnetic pulses can be output to the workpiece for composite strengthening during shot peening. The skin effect of eddy current generated by electromagnetic pulses is used to form an induced current with a certain depth on the surface of the workpiece. Through the coupling of shot peening impact, electroplasticity, eddy current thermal effect and magnetoplasticity, the cold deformation and plasticity of the material surface are improved, so as to achieve the effect of increasing the depth of shot peening, so as to form a residual compressive stress layer with higher residual stress and deeper distribution on the surface of the workpiece. The use of non-contact induction coils to provide electromagnetic pulses can ensure the uniformity and stability of the electromagnetic field, while avoiding electromagnetic interference from surrounding equipment or devices themselves; at the same time, it can avoid the local overheating of the contact electrodes required by pulsed DC or AC power to generate alternating electromagnetic fields at the contact position of the workpiece due to contact resistance, and can also prevent parts with complex surfaces such as engine blades from being damaged by the contact power supply during processing.

[0006] Further, in some embodiments, the pair of induction coils are arranged horizontally; the ultrasonic vibration device includes a vibration head, which is vertically arranged in the processing cabin, and a processing area is formed above the vibration head; the vertically arranged vibration head is conducive to the shot peening falling back by gravity, and the induction coil and the vibration head are arranged perpendicular to each other to avoid the pulse magnetic field from interfering with the metal parts in the ultrasonic vibration device.

[0007] Furthermore, in some embodiments, the upper surface of the vibration head is configured as a steepest descent linear curved surface. The steepest descent linear curved surface can make the shot fall back faster.

[0008] Furthermore, in some embodiments, shot peening is provided in the processing chamber, and the shot peening is spread on the surface of the vibration head in a single layer. The single-layered shot peening can reduce the energy loss caused by the collision between the shots, and improve the shot peening efficiency.

[0009] Furthermore, in some embodiments, the vibration head and the processing chamber are clearance-matched, and the single-side clearance is less than 1 / 4 of the shot peening radius, and a lubricant or lubrication structure is provided in the clearance. The clearance match ensures the free vibration of the vibration head and avoids energy loss caused by friction; and controlling the clearance size is used to prevent the shot peening from leaking or getting stuck.

[0010] Furthermore, in some embodiments, the vibration head is provided with a cooling structure, which is used to cool the vibration head to avoid the vibration head from getting stuck due to overheating or the hardness of the shot peening being reduced.

[0011] Furthermore, in some embodiments, the processing chamber includes a clamping tool, which provides a horizontal clamping direction to allow one end of the workpiece to be processed to be fixed to the clamping tool and arranged in the processing chamber along the clamping direction. The clamping tool arranged in the horizontal direction can reduce the blocked area of ​​the workpiece to be processed.

[0012] Furthermore, in some embodiments, the clamping tool includes a rotating mechanism to allow the clamping tool to rotate around an axis parallel to the clamping direction. The clamping tool can fully peen the surface of the workpiece to be processed by self-rotation to avoid obstruction. At the same time, the self-rotating clamping tool can completely enclose parts with complex surfaces such as engine blades in the processing chamber, and the self-rotation of the tool can fully strengthen the shot peening of various areas of the workpiece to be processed, especially the edge areas (such as the intake and exhaust edges of the blades).

[0013] Furthermore, in some embodiments, the clamping tool is at least partially made of insulating material. The insulating material prevents the clamping tool itself from generating induced current under the influence of the electromagnetic pulse, causing energy loss or affecting the operation of the device.

[0014] Furthermore, in some embodiments, the vibration frequency provided by the ultrasonic vibration device is 20kHz-30kHz, and the amplitude output into the processing chamber is 10μm-30μm.

[0015] According to another embodiment of the present invention, there is provided an ultrasonic shot peening surface strengthening method, which uses the ultrasonic shot peening surface strengthening device provided in any of the aforementioned embodiments and includes the following steps: sending the part to be processed into the processing chamber and fixing it; starting the induction coil to output a pulsed electromagnetic field to the part to be processed, so that an induced current is formed on the surface of the part to be processed; starting the ultrasonic oscillator to perform shot peening on the surface of the part to be processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of an ultrasonic shot peening surface strengthening device in one embodiment;

[0017] Figure 2 This is a schematic diagram of the partial structure of the induction coil and the processing chamber in one embodiment;

[0018] Figure 3a This is a schematic diagram of the structure of a vibration head in one embodiment;

[0019] Figure 3b Schematic diagram of the cross-sectional structure of a vibration head in one embodiment.

[0020] The meaning of the reference numerals: 1-workbench; 11-through hole; 2-processing cabin; 20-shot peening; 21-processing space; 31-induction coil; 32-connecting rod; 41-workpiece fixture; 42-rotating motor; 43-holder; 44-side fixture; 45-support rod; 46-driving device; 51-vibration head; 52-amplitude rod; 53-processing surface; 54-side wall of vibration head.

[0021] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below through specific embodiments combined with the accompanying drawings.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0024] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, which can be a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0025] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0026] In the description herein, "plurality" means at least two.

[0027] Shot peening can effectively introduce a residual compressive stress layer on the surface of the material, thereby achieving surface strengthening of the material and improving the fatigue performance of the parts. The thickness of the residual compressive stress layer has a significant impact on the strengthening effect of the parts. When the shot peening impact energy is low, the residual compressive stress depth is insufficient; when the shot peening impact energy is high, the surface of the material is prone to quickly form a high hardness layer due to work hardening, which also leads to a low depth of residual compressive stress. These factors restrict the strengthening effect of shot peening on metal parts.

[0028] In order to solve the above problems, an embodiment of the present invention provides a super shot peening surface strengthening device, which enhances the shot peening effect through electromagnetic pulse assistance and increases the thickness of the residual compressive stress layer.

[0029] The structure of the device is as follows Figure 1 As shown, it includes a workbench 1 as a support, and an ultrasonic shot peening system is arranged on the workbench 1. The system includes a processing cabin 2 and an ultrasonic oscillating device. Figure 2 The ultrasonic oscillator is arranged below the workbench 1, and includes an ultrasonic generator (not shown), an ultrasonic transducer (not shown), an horn 52 and a vibration head 51 connected in sequence. The ultrasonic generator generates a signal of a certain frequency, and the ultrasonic transducer converts the signal into a mechanical amplitude, which is amplified by the horn 52 and input into the processing cabin 2 along the vertical direction by the vibration head 51 to provide ultrasonic vibration reciprocating up and down, and a processing space 21 is formed above the vibration head 51. The shot 20 is spread over the vibration head 51, and the vibration head transfers energy to the shot 20, and the shot impacts the workpiece to be processed upward to realize shot peening. A pair of induction coils 31 are arranged on both sides of the processing cabin 2, and the induction coils 31 are connected by multiple connecting rods 32 to form a coaxial horizontal arrangement. The cylindrical surface surrounded by the two induction coils 31 as the ends surrounds the processing cabin 2 inside, and the processing cabin 2 is arranged on the axis of the induction coil 31; a through hole 11 is arranged at a corresponding position on the workbench 1 for the induction coil 31 to pass from below. Outside the two induction coils 31, a rotating motor 42 is provided at one end of the workbench 1. The rotating motor 42 drives the long rod-shaped workpiece fixture 41 to penetrate into the processing chamber 2 along the axial direction of the induction coil 31. A clamping seat 43 is provided between the processing chamber 2 and the rotating motor 42 to provide support for the workpiece fixture 41. The workpiece fixture 41 clamps and fixes the part to be processed (not shown) in the processing chamber 2 to form a clamping direction parallel to the axial direction of the induction coil 31, and can rotate around an axis parallel to the clamping direction driven by the rotating motor 42. During the shot peening process, the induction coil 31 outputs a pulse current, and a high-frequency pulse electromagnetic field is formed between the two induction coils, so that an induced current is generated on the surface of the part to be processed. Under the action of the electroplasticity, eddy current thermal effect and electromagnetic field magnetoplasticity of the induced current, the impact force of the shot peening 20 on the workpiece can be transmitted to a deeper position of the part, forming a thicker residual compressive stress layer, thereby improving the shot peening strengthening effect.

[0030] In a preferred embodiment, the ultrasonic generator can at least provide a signal with a frequency of 20 kHz-30 kHz, and the amplitude range of the vibration head 51 output to the processing chamber 2 is 10 μm-30 μm.

[0031] In some embodiments, depending on the structure of the workpiece to be processed, the clamping tool can also be arranged at an angle or extend vertically from the top of the processing chamber 2, for example, to perform single-sided strengthening processing on a disc-shaped part. Correspondingly, the ultrasonic oscillator and the induction coil 31 can also be arranged horizontally, vertically or tilted. In some embodiments, when only one side or a specific area of ​​the part needs to be shot peened, the rotating motor 42 can be disabled or omitted in the structure.

[0032] In some embodiments, when processing the rod, the long rod-shaped workpiece fixture 41 can be omitted, and the rod is directly fixed on the rotating motor 42, so that the rod is directly extended into the processing cabin 2 to complete the processing. In these embodiments, the rotating motor 42 can be installed on a slide that can slide axially along the induction coil 31.

[0033] In a preferred embodiment, the processing chamber 2 and the workpiece fixture 41 between the two induction coils 31 are made of insulating materials such as engineering plastics or ceramics, or are insulated by coating or plating an insulating layer on the surface to prevent the induced current generated on the surface of the processing chamber 2 or the workpiece fixture 41 from affecting the normal operation of the device.

[0034] In a preferred embodiment, if Figure 3a As shown, the processing surface 53 formed on the upper surface of the vibration head 51 is configured as a concave structure, and the shot peening 20 is spread on the processing surface 53 in a single layer to reduce the energy loss caused by the collision between the shot peening 20. In a preferred embodiment, as shown in FIG. Figure 3b As shown, the processing surface 53 is configured as a brachistodes surface, that is, the cross-sectional profile of the processing surface 53 forms a brachistodes curve, so as to reduce the time consumed by the shot peening 20 to fall and improve the shot peening efficiency. In a preferred embodiment, the vibration head 51 and the processing chamber 20 are in a clearance fit to reduce the loss of vibration energy due to friction; the single-sided gap between the vibration head 51 and the processing chamber 20 is less than 1 / 4 of the radius of the shot peening 20 to avoid the shot peening from leaking out or getting stuck in the gap during the vibration process. At the same time, a lubricant such as lubricating oil or solid lubricant is provided in the fitting gap, or a lubricating structure is provided on the surface of the vibration head side wall 54, such as a self-lubricating material layer. A cooling structure, such as a cooling air trough or a cooling flow channel, is provided in the vibration head 51 to avoid the influence of temperature increase on the shot peening effect.

[0035] In a preferred embodiment, the process of shot peening using the ultrasonic shot peening surface strengthening device provided in the above embodiment is as follows:

[0036] First, the processing cabin 2 is opened, the compressor blade to be processed is clamped and fixed on the workpiece fixture 41, the workpiece fixture 41 is installed in the rotating motor 42, and its axial position is adjusted so that the compressor blade is completely contained in the processing cabin 2, and the processing cabin is closed. The support rod 45 is driven by the driving device 46, and the side fixture 44 clamps the processing cabin 2 from both sides to prevent the vibration amplitude from exceeding the limit value during the shot peening process.

[0037] Next, the output parameters of the induction coil 31 and the ultrasonic oscillator are adjusted. The ultrasonic vibration frequency is set to 20kHz-30kHz and the amplitude is set to 10μm-30μm according to the surface processing requirements of the vortex blades. The speed of the rotating motor 42 is set. According to the processing requirements of different parts, the rotation of the rotating motor 42 during the processing process can be uniform rotation, variable speed rotation or intermittent rotation.

[0038] Subsequently, the ultrasonic shot peening surface strengthening device is started to start the shot peening process. Under the action of the electromagnetic pulse generated by the induction coil 31, an induced current is generated on the surface of the compressor blade. Under the combined action of magnetoplasticity, electroplasticity and eddy current thermal effect, the deformation resistance of the surface material is reduced, and the depth of the residual compressive stress layer generated by the shot peening process and the magnitude of the residual compressive stress value are effectively increased.

[0039] Finally, after reaching the predetermined processing time, the ultrasonic shot peening surface strengthening device is turned off, the side clamp 44 is loosened, the processing cabin 2 is opened, and the compressor blade is taken out.

[0040] It should be understood that the above operation process is not unique. In different embodiments, the above steps can be adaptively adjusted according to the specific structure of the ultrasonic shot peening surface strengthening device and the size, structure and processing requirements of the parts to be processed. According to the difference in part material, structure and processing requirements, processing parameters such as ultrasonic frequency, amplitude, frequency and intensity of pulse current, and material and size of shot peening can be adaptively adjusted.

[0041] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure or method steps involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. An ultrasonic shot peening surface strengthening device, comprising an ultrasonic shot peening system, wherein the ultrasonic shot peening system comprises a processing cabin for ultrasonic shot peening strengthening and an ultrasonic oscillating device, characterized in that: The ultrasonic shot peening surface strengthening device also includes a pair of induction coils, which are coaxially arranged. The processing chamber is arranged on the axis between the pair of induction coils, so that the processing chamber is surrounded by a cylindrical surface with the pair of induction coils as ends.

2. The ultrasonic shot peening surface strengthening device according to claim 1, characterized in that: The pair of induction coils are arranged horizontally; the ultrasonic vibration device includes a vibration head, which is vertically arranged in the processing cabin and forms a processing area above the vibration head.

3. The ultrasonic shot peening surface strengthening device according to claim 2, characterized in that: The upper surface of the vibration head is configured as a steepest descent linear curved surface.

4. The ultrasonic shot peening surface strengthening device according to claim 2 or 3, characterized in that: Shot peening is arranged in the processing cabin, and the shot peening is spread on the surface of the vibration head in a single layer.

5. The ultrasonic shot peening surface strengthening device according to claim 4, characterized in that: The vibration head and the processing chamber are clearance-matched, and the single-side clearance is smaller than 1 / 4 of the shot peening radius. A lubricant or a lubricating structure is provided in the clearance.

6. The ultrasonic shot peening surface strengthening device according to claim 2 or 3, characterized in that: The vibration head is provided with a cooling structure.

7. The ultrasonic shot peening surface strengthening device according to claim 1 or 2, characterized in that: The processing chamber includes a clamping tool, which provides a horizontal clamping direction to allow one end of a workpiece to be processed to be fixed to the clamping tool and arranged in the processing chamber along the clamping direction.

8. The ultrasonic shot peening surface strengthening device according to claim 7, characterized in that: The clamping tool comprises a rotating mechanism to allow the clamping tool to rotate around an axial direction parallel to the clamping direction.

9. The ultrasonic shot peening surface strengthening device according to claim 7, characterized in that: The clamping tool is at least partially made of insulating material.

10. The ultrasonic shot peening surface strengthening device according to claim 1 or 2, characterized in that: The vibration frequency provided by the ultrasonic vibration device is 20kHz-30kHz, and the amplitude output into the processing chamber is 10μm-30μm.

11. A surface strengthening method by ultrasonic shot peening, characterized in that: The ultrasonic shot peening surface strengthening device as claimed in any one of claims 1 to 10 is used to perform surface shot peening strengthening on the part to be processed, and the method comprises the following steps: Sending the parts to be processed into the processing cabin and fixing them; Starting the induction coil to output a pulse electromagnetic field to the workpiece to be processed, so that an induced current is formed on the surface of the workpiece to be processed; The ultrasonic vibration device is started to perform shot peening on the surface of the part to be processed.

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