Axial ultrasonic-assisted micro-forging surface strengthening device

Abstract

The invention provides an axial ultrasonic-assisted micro-forging surface strengthening device which comprises a micro-forging system and an ultrasonic peening system, and the micro-forging system and the ultrasonic peening system are fixedly connected. The micro-forging system is used for generating low-frequency large-amplitude impact motion, and the ultrasonic impact system is used for generating high-frequency small-amplitude impact motion. The micro-forging system and the ultrasonic peening system are combined, and composite peening on the surface of the part can be achieved. The composite impact process of low-frequency large-stroke impact motion driven by an electromagnetic system in the axial direction of the punch and high-frequency small-stroke impact motion driven by an ultrasonic system is achieved, the impact influence depth of the composite impact motion on parts is deeper, the microstructure change is larger, and the residual stress introduction is larger and deeper. Meanwhile, the device is compact in structure and can be directly integrated on a machine tool spindle through a designed mechanical interface, and the whole device is high in integration degree. In addition, the two kinds of strengthening punches of the firing pin and the micro forging heads with different diameters are arranged, and different strengthening effects can be achieved.

Description

Technical Field

[0001] The invention relates to the field of mechanical processing, in particular to an axial ultrasonic assisted micro-forging surface strengthening device. Background Art

[0002] Micro-forging is an emerging mechanical surface modification process that involves using a high-hardness hammer head with high frequency oscillation to hammer the target area. The schematic diagram of the structure of a typical micro-forging device is shown in Figure 2. Figure 1 As shown, the impact structure performs reciprocating linear motion between the limit block and the workpiece surface under the stimulation of the drive system. After the material is subjected to the continuous impact of protons, strong plastic deformation occurs. A certain plastic deformation can improve the surface integrity of the material. The control system can be used to adjust the impact frequency and impact energy, and the cooling system dissipates heat and ensures the stable operation of the system. The micro-forging device is generally installed at the end of the machine tool or the robotic arm through a mechanical interface to adjust the process parameters such as stroke, step distance, line distance, and impact angle. During the processing, the micro-forging head always maintains a constant distance from the workpiece surface to ensure that the workpiece material is subjected to an impact with precise position and uniform intensity. The surface finishing or strengthening of workpieces made of different metal materials can be achieved through precise high-frequency impact.

[0003] Ultrasonic impact technology is an efficient method to eliminate harmful residual tensile stress on the surface of components and introduce beneficial compressive stress. The schematic diagram of a typical ultrasonic micro-forging impact equipment is as follows: Figure 2 As shown, it is mainly composed of four parts: ultrasonic generator, ultrasonic transducer, amplitude rod and impact head. The ultrasonic generator is a high-frequency circuit that generates high-frequency electrical energy. The ultrasonic transducer converts the high-frequency electrical energy into mechanical vibration, which is then amplified by the amplitude rod. Finally, the mechanical vibration is transmitted to the impact head. The impact head contacts the workpiece and transmits the ultrasonic vibration to the surface of the workpiece to achieve a strengthening effect.

[0004] The ultrasonic generator generates a high-frequency ultrasonic impact device that uses high-power energy to drive the impact head to impact the surface of the metal object at a frequency of about 20,000 times per second. The high frequency, high efficiency and high energy under focus cause the metal surface to produce a large compressive plastic deformation; at the same time, the ultrasonic impact changes the original stress field and produces beneficial compressive stress; under high-energy impact, the temperature of the metal surface rises rapidly and then cools rapidly, causing the surface metal structure of the action area to change and the impact site to be strengthened.

[0005] The existing Chinese patent with publication number CN117920925A discloses an electromagnetic micro-forging device with active stroke adjustment, including an upper limit active adjustment structure and an electromagnetic micro-forging drive structure; the electromagnetic micro-forging drive structure includes a first housing, a drive assembly, an intermediate connecting rod and a micro-forging head; the micro-forging head is installed at the bottom end of the intermediate connecting rod, and the drive assembly is used to drive the intermediate connecting rod to reciprocate up and down; the upper limit active adjustment structure is installed above the electromagnetic micro-forging drive structure, and is used to adjust the highest position of the reciprocating motion of the intermediate connecting rod. The upper limit active adjustment structure includes an active adjustment structure drive member, a transmission member, a screw rod and a movable upper limit block; the present invention can actively adjust the position of the movable upper limit block through the design of the upper limit active adjustment structure to achieve the adjustable upper limit position of the intermediate connecting rod, thereby controlling the stroke of the micro-forging and achieving the purpose of online regulation of the micro-forging effect.

[0006] The disadvantage of the prior art is that only a relatively single process is used to strengthen the material, and the plastic deformation and strengthening effect of the single process on the part material are limited. Summary of the invention

[0007] In view of the defects in the prior art, an object of the present invention is to provide an axial ultrasonic assisted micro-forging surface strengthening device.

[0008] According to the present invention, an axial ultrasonic-assisted micro-forging surface strengthening device is provided, comprising: a micro-forging system and an ultrasonic impact system, wherein the micro-forging system is used to generate low-frequency large-amplitude impact motion, and the ultrasonic impact system is used to generate high-frequency small-amplitude impact motion; the axial output generated by the micro-forging system is combined with the axial output generated by the ultrasonic impact system.

[0009] Preferably, the axial ultrasonic-assisted micro-forging surface strengthening device comprises an ultrasonic transducer, an ultrasonic amplitude transformer and a punch connected in sequence; the output shaft of the micro-forging system is connected to the ultrasonic transducer so that the punch moves axially; the ultrasonic generator of the ultrasonic impact system is connected to the ultrasonic transducer through a wire so that the punch moves axially.

[0010] Preferably, the low-frequency large-amplitude impact motion is hundreds of hertz and millimeter-level stroke motion, and the high-frequency small-amplitude impact motion is tens of thousands of hertz and micrometer-level stroke motion.

[0011] Preferably, the micro-forging system comprises a driving assembly, which is drivingly connected to an output shaft of the micro-forging system, and the driving assembly comprises a pneumatic driving assembly, a piezoelectric driving assembly and an electromagnetic driving assembly.

[0012] Preferably, the electromagnetic drive assembly comprises: a micro-forging base, a permanent magnet, a coil support and an excitation coil, the permanent magnet is fixedly mounted on the micro-forging base, the excitation coil is wound on the coil support, and the excitation coil is coupled to the permanent magnet; a connecting rod is connected to the coil support as the output shaft of the micro-forging system.

[0013] Preferably, an upper limit block is provided at one end of the micro-forging base axially away from the punch, and the upper limit block limits the axial displacement of the connecting rod; and a mechanical interface is provided on the top of the upper limit block.

[0014] Preferably, the ultrasonic impact system comprises an ultrasonic shell, the ultrasonic transducer and the ultrasonic horn are both located inside the ultrasonic shell, and an ultrasonic cooling air interface is provided on the ultrasonic shell for introducing compressed gas into the ultrasonic shell.

[0015] Preferably, an ultrasonic circuit interface is provided on the ultrasonic housing, and the ultrasonic generator is connected to the ultrasonic circuit interface and the ultrasonic transducer in sequence through a wire.

[0016] Preferably, the punch includes at least two strikers, and the ultrasonic shell is provided with a hole-opening mold at the position where it cooperates with the punch. The aperture of the mold is not smaller than the aperture of the striker. An L-shaped structure is provided at the root of the striker. The striker passes through the aperture of the mold. The L-shaped structure clamps the striker on the mold, and the non-impact surface of the L-shaped structure cooperates with the ultrasonic shell limiter.

[0017] Preferably, the punch includes a striker, and the striker is fixedly connected to the ultrasonic horn via a fastener.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention combines the micro-forging system with the ultrasonic impact system to simultaneously realize a composite impact process in which the electromagnetic system drives the punch axially with a low-frequency and large-stroke impact motion (hundreds of hertz, millimeter-level stroke) and the ultrasonic system drives a high-frequency and small-stroke impact motion (tens of thousands of hertz, micrometer-level stroke), thereby achieving more effective strengthening of parts.

[0020] 2. The present invention adopts a compact structural design so that the device can be directly installed on the main shaft of a machine tool through a mechanical interface, and the whole device has a high degree of integration.

[0021] 3. The present invention helps to achieve different strengthening effects through diversified punch designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0023] Figure 1 The present invention mainly embodies the structural schematic diagram of a typical micro-forging device in the background technology;

[0024] Figure 2 The present invention mainly embodies a schematic diagram of a typical ultrasonic micro-forging impact device in the background technology;

[0025] Figure 3 It is a schematic diagram of the overall structure of the strengthening device in the specific embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of two punch structures in a specific implementation manner of the present invention.

[0027] As shown in the figure: 1. Micro-forging cold air interface; 2. Micro-forging base; 3. Bearing; 4. Ultrasonic cold air interface; 5. Ultrasonic transducer; 6. Ultrasonic amplitude transformer; 7. Mechanical interface; 8. Upper limit block; 9. Coil support; 10. Permanent magnet; 11. Excitation coil; 12. Micro-forging circuit interface; 13. Connecting rod; 14. Ultrasonic circuit interface; 15. Ultrasonic generator; 16. Ultrasonic housing; 17. Punch. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0029] According to the axial ultrasonic assisted micro-forging surface strengthening device provided by the present application, Figure 3 As shown, it includes a micro-forging system and an ultrasonic impact system, and the micro-forging system and the ultrasonic impact system are combined. The micro-forging system is used to generate low-frequency and large-amplitude impact motion, and the ultrasonic impact system is used to generate high-frequency and small-amplitude impact motion. The combination of the micro-forging system and the ultrasonic impact system can achieve composite impact strengthening of the surface of the parts.

[0030] It also includes an ultrasonic transducer 5 and a punch 17 connected in sequence. The output shaft of the micro-forging system is connected to the ultrasonic transducer 5 to enable the punch 17 to move axially. The ultrasonic generator 15 of the ultrasonic impact system is connected to the ultrasonic transducer 5 through a wire to enable the punch 17 to move axially.

[0031] The present application designs an axial ultrasonic-assisted micro-forging surface strengthening device, which realizes a composite impact process of axial low-frequency large-stroke impact motion (hundreds of hertz, specifically 100HZ-999HZ, millimeter-level stroke) of the micro-forging system and high-frequency small-stroke impact motion driven by the ultrasonic system (tens of thousands of hertz, specifically 10000HZ-99999HZ, micron-level stroke). The composite impact motion of high and low frequencies and large and small strokes can achieve more effective strengthening of parts (deeper impact impact depth, greater microstructure changes, greater and deeper residual stress introduction, etc.). The device and strengthening method are of great significance for material strengthening and workpiece performance improvement.

[0032] Specifically, the micro-forging system includes a drive assembly, which is in driving connection with the output shaft of the micro-forging system. The drive assembly includes a pneumatic drive assembly, a piezoelectric drive assembly, and an electromagnetic drive assembly.

[0033] The present application is described by taking the electromagnetic drive assembly as an example: the electromagnetic drive assembly includes: a micro-forging base 2, a permanent magnet 10, a coil support 9 and an excitation coil 11, the permanent magnet 10 is fixedly mounted on the micro-forging base 2, the excitation coil 11 is wound on the coil support 9, and the excitation coil 11 is coupled with the permanent magnet (10). A connecting rod 13 is connected to the coil support 9 as the output shaft of the micro-forging system. Specifically, the micro-forging base 2 has a central opening, and the drive assembly and the transmission assembly are both installed inside the opening of the micro-forging base 2. The permanent magnet 10 is fixedly mounted inside the opening of the micro-forging base 2, the excitation coil 11 is wound on the coil support 9, the coil support 9 is fixedly connected to the connecting rod 13, and the connecting rod 13 passes through the through hole of the micro-forging base 2 as a whole and extends out. A micro-forging circuit interface 12 is provided on the micro-forging base 2. When an alternating current is passed into the micro-forging circuit interface 12, an electromagnetic field is generated due to the principle of electromagnetic interaction. Under the fixed magnetic field of the permanent magnet 10, a corresponding electromagnetic force is generated to drive the connecting rod 13 fixedly connected to the coil support 9 to make axial movement.

[0034] An upper limit block 8 is provided at one end of the micro-forging base 2 axially away from the punch 17, and the upper limit block 8 limits the axial displacement of the connecting rod 13. A mechanical interface 7 is provided on the top of the upper limit block 8. A micro-forging cold air interface 1 is provided on the micro-forging base 2 for introducing compressed air to cool the equipment.

[0035] Working principle: When an alternating current of a certain frequency is passed through the excitation coil 11, an alternating electromagnetic force of a corresponding frequency will be generated, thereby driving the punch 17 system to produce periodic motion. The punch 17 is subjected to a corresponding reaction force when it impacts the workpiece downward and the upper end of the connecting rod 13 impacts the upper limit block 8. A dynamic balance is formed between the alternating electromagnetic force and the reaction force. The micro-forging head realizes reciprocating mechanical impact motion, continuously impacting the surface of the part to achieve a mechanical strengthening effect. Since the electromagnetic drive process generates heat, compressed air is introduced into the micro-forging cold air interface 1 to achieve cooling of the electromagnetic micro-forging drive system. The device can be directly installed on the machine tool spindle through the designed mechanical interface 7, and the device has a high degree of integration.

[0036] The ultrasonic impact system comprises an ultrasonic housing 16, an ultrasonic generator 15, an ultrasonic transducer 5, an ultrasonic horn 6, and a punch 17. A through hole is provided in the center of the ultrasonic housing 16, and the ultrasonic transducer 5 and the ultrasonic horn 6 are both installed inside the ultrasonic housing 16. An ultrasonic circuit interface 14 is provided on the ultrasonic housing 16, and the ultrasonic generator 15 is connected to the ultrasonic transducer 5 through the ultrasonic circuit interface 14 in sequence through a wire. The extending part of the micro-forging system connecting rod 13 passes through the ultrasonic transducer 5 and the ultrasonic horn 6, and the connecting rod 13 is fixedly connected to the ultrasonic transducer 5 and the ultrasonic horn 6. At the same time, the connecting rod 13 is integrally inserted into the ultrasonic housing 16. An ultrasonic cooling air interface 4 is provided on the ultrasonic housing 16 to pass compressed gas into the ultrasonic housing 16 to cool the equipment.

[0037] The ultrasonic transducer 5 and the punch 17 are fixedly connected to the output shaft of the micro-forging system, and are driven by the output shaft of the micro-forging system to make axial movement. The ultrasonic generator 15 is connected to the ultrasonic transducer 5 through a wire. The ultrasonic transducer 5 is fixedly connected to the ultrasonic horn 6.

[0038] Working principle: The ultrasonic generator 15 generates a high-frequency ultrasonic electrical signal, which is transmitted to the ultrasonic transducer 5 through the ultrasonic circuit interface 14. The ultrasonic transducer 5 converts the ultrasonic electrical signal into ultrasonic mechanical vibration, and then the mechanical vibration is amplified and transmitted to the punch 17 through the ultrasonic amplitude transformer 6, thereby realizing high-frequency vibration of the punch 17, thereby realizing high-frequency ultrasonic impact on the parts.

[0039] The ultrasonic system and the micro-forging system can be rigidly connected via the threads of the intermediate connecting rod 13 .

[0040] The punch 17 of the technical solution of this application has the following two designs:

[0041] like Figure 4As shown, one is a non-fixed connection striker on the left side. The punch includes at least two strikers, and the ultrasonic housing 16 is provided with an opening mold at the place where it cooperates with the punch 17. The mold aperture is not less than the striker aperture. An L-shaped structure is provided at the root of the striker. The striker passes through the mold aperture. The L-shaped structure clamps the striker on the mold, and the non-impact surface of the L-shaped structure cooperates with the ultrasonic housing 16. Specifically, a plurality of strikers are limited by the ultrasonic housing 16 and can only move axially. The high-frequency vibration at the output end of the ultrasonic transformer 6 will impact the striker, so that the striker vibrates and impacts at a high frequency between the output end of the ultrasonic transformer 6 and the workpiece; another design is a punch 17 with different outer diameters, which is fixedly connected to the ultrasonic transformer 6 by a thread, so that the punch 17 can be replaced with different materials and shapes and sizes, and vibrates and impacts with the ultrasonic transformer 6 according to the ultrasonic output vibration frequency.

[0042] The other is a fixedly connected striker, the punch 17 includes a striker, and the striker is fixedly connected to the ultrasonic horn 6 by a fastener. Specifically, the ultrasonic housing 16 and the micro-forging housing can be fixedly connected by bolts.

[0043] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An axial ultrasonic assisted micro-forging surface strengthening device, characterized in that: include: A micro-forging system and an ultrasonic impact system, wherein the micro-forging system is used to generate low-frequency large-amplitude impact motion, and the ultrasonic impact system is used to generate high-frequency small-amplitude impact motion; The axial output generated by the micro-forging system is combined with the axial output generated by the ultrasonic impact system.

2. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 1, characterized in that: The invention comprises an ultrasonic transducer (5) and a punch (17) connected in sequence, wherein the output shaft of the micro-forging system is connected to the ultrasonic transducer (5) so that the punch (17) moves axially, and the ultrasonic generator (15) of the ultrasonic impact system is connected to the ultrasonic transducer (5) via a wire so that the punch (17) moves axially.

3. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 1, characterized in that: The low-frequency and large-amplitude impact motion is hundreds of hertz and millimeter-level stroke motion; The high-frequency small-amplitude impact motion is tens of thousands of hertz and micron-level stroke motion.

4. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 2, characterized in that: The micro-forging system comprises a driving assembly, and the driving assembly is drivingly connected to an output shaft of the micro-forging system; The driving assembly includes a pneumatic driving assembly, a piezoelectric driving assembly and an electromagnetic driving assembly.

5. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 4, characterized in that: The electromagnetic drive assembly comprises: a micro-forging base (2), a permanent magnet (10), a coil support (9) and an excitation coil (11), wherein the permanent magnet (10) is fixedly mounted on the micro-forging base (2), the excitation coil (11) is wound on the coil support (9), and the excitation coil (11) is coupled to the permanent magnet (10); The coil support (9) is connected with a connecting rod (13) as an output shaft of the micro-forging system.

6. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 2, characterized in that: An upper limit block (8) is provided at one end of the micro-forging base (2) axially away from the punch (17), and the upper limit block (8) limits the axial displacement of the connecting rod (13); A mechanical interface (7) is provided on the top of the upper limit block (8).

7. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 2, characterized in that: The ultrasonic impact system comprises an ultrasonic shell (16), the ultrasonic transducer (5) is located inside the ultrasonic shell (16), and an ultrasonic cooling air interface (4) is provided on the ultrasonic shell (16) for introducing compressed gas into the ultrasonic shell (16).

8. The axial ultrasonic-assisted micro-forging surface strengthening device according to claim 7, characterized in that: The ultrasonic housing (16) is provided with an ultrasonic circuit interface (14), and the ultrasonic generator (15) is connected to the ultrasonic circuit interface (14) and the ultrasonic transducer (5) in sequence through a wire.

9. The axial ultrasonic-assisted micro-forging surface strengthening device according to claim 4, characterized in that: The punch (17) comprises at least two strikers, and the ultrasonic housing (16) is provided with a hole-opening die at a position where it cooperates with the punch (17), the die aperture is not less than the striker aperture, an L-shaped structure is provided at the root of the striker, the striker passes through the die aperture, the L-shaped structure clamps the striker on the die, and the non-impact surface of the L-shaped structure cooperates with the ultrasonic housing (16) in a limiting manner.

10. The axial ultrasonic assisted micro-forging surface strengthening device according to claim 4, characterized in that: The punch (17) comprises a striker, which is fixedly connected to the ultrasonic horn (6) via a fastener.

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