Ultrasonic auxiliary grinding device for amplitude-change pole with small length-diameter ratio and operation method of ultrasonic auxiliary grinding device

Abstract

The invention discloses an ultrasonic-assisted grinding device for a small-length-diameter-ratio amplitude-change pole. The ultrasonic-assisted grinding device comprises an ultrasonic generator and a grinding device body. The ultrasonic generator is used for emitting ultrasonic-frequency electric signals and is in electric signal connection with the grinding device; the grinding device comprises piezoelectric ceramics, an amplitude-change pole and a grinding wheel; the piezoelectric ceramic and the grinding wheel are assembled at the two ends of the amplitude-change pole; the piezoelectric ceramic is used for receiving electric signals sent by the ultrasonic generator and converting the electric signals into mechanical vibration, and the mechanical vibration is transmitted to the grinding wheel through the amplitude-change pole. Ultrasonic frequency electric signals sent by the ultrasonic generator are received by the piezoelectric ceramics and efficiently converted into mechanical vibration, the conversion process is rapid, energy loss is small, and it is ensured that the mechanical vibration can be stably and continuously transmitted to the grinding wheel. The mechanical vibration is transmitted to the grinding wheel through the amplitude-change pole, so that the grinding wheel generates high-frequency micro-amplitude ultrasonic vibration in the grinding process, the grinding temperature is reduced, and the grinding efficiency and the machining quality are remarkably improved, for example, the surface roughness is reduced, and the surface smoothness is improved.

Description

Technical Field

[0001] The invention relates to the field of ultrasonic grinding, in particular to an ultrasonic auxiliary grinding device of a variable amplitude rod with a small aspect ratio and an operating method thereof. Background Art

[0002] As a kind of precision basic parts, the main function of bearings is to support mechanical rotating bodies, reduce their friction coefficient during movement, and ensure the rotation accuracy of rotating bodies during operation. Therefore, the quality of bearings has an important impact on the overall operating efficiency, service life and safety of the equipment. Bearings are mainly composed of inner and outer rings, rollers and cages. The accuracy level of the inner and outer rings and the contact surface with the rollers directly affects the friction coefficient of the bearings. For the ring parts, their shape and position accuracy are mainly guaranteed by the grinding process, so the grinding process level is closely related to the bearing performance level.

[0003] At present, the main processing method for deep groove ball bearing rings is still grinding with a grinding wheel, but there are common problems such as rapid passivation of abrasive grains on the grinding wheel surface, high grinding heat and poor consistency of workpiece processing, which affect the overall processing efficiency and surface quality. Ultrasonic assisted grinding technology is an ultra-precision processing method that combines ultrasonic processing technology with ordinary grinding technology. It can change the contact state between abrasive grains and workpieces. Compared with ordinary grinding, it has the advantages of reducing surface damage and improving processing quality. Chinese patent application number CN201320125984.7 discloses an ultrasonic vibration internal grinding device. On the basis of the original grinding equipment, axial ultrasonic vibration is applied to the grinding wheel to achieve ultrasonic grinding of the inner circle of the bearing. Chinese patent application number CN201410024755.5 discloses an axial ultrasonic vibration high-speed grinding device for micro-bearing inner circle finishing. By applying axial high-frequency micro-amplitude ultrasonic vibration on the grinding wheel, the problem of unstable part processing quality is improved, and the grinding efficiency and workpiece surface quality are improved.

[0004] Although there are many studies on ultrasonic assisted grinding technology, there are few applications of ultrasonic assisted grinding for the inner groove of bearing rings, and most processing methods are still ordinary grinding, which has low processing efficiency and general processing quality. In addition, in the current ultrasonic vibration assisted grinding, since the size design of the amplitude rod must meet the ultrasonic theory, its size aspect ratio is large. Since the grinding rod body is arranged in the form of a cantilever beam, the large aspect ratio can easily cause the rod body to vibrate during high-speed rotation, resulting in poor surface quality after processing and difficult to ensure safety during processing. Summary of the invention

[0005] In order to overcome the above-mentioned defects in the prior art, a small aspect ratio horn ultrasonic assisted grinding device and an operating method thereof are provided.

[0006] The technical solution of the present invention is as follows: a small aspect ratio amplitude transformer ultrasonic assisted grinding device, comprising an ultrasonic generator and a grinding device; the ultrasonic generator is used to emit an electrical signal of ultrasonic frequency, which is connected to the electrical signal of the grinding device; the grinding device comprises piezoelectric ceramics, an amplitude transformer and a grinding wheel; the piezoelectric ceramics and the grinding wheel are assembled at both ends of the amplitude transformer; the piezoelectric ceramics are used to receive the electrical signal emitted by the ultrasonic generator and convert it into mechanical vibration, and the mechanical vibration is transmitted to the grinding wheel through the amplitude transformer.

[0007] Preferably, the middle portion of the amplitude transformer is in a stepped shape.

[0008] Preferably, it also includes an electric spindle, a fixed seat and a frame. The electric spindle is wrapped and fixed by the fixed seat, and the grinding device is assembled on the electric spindle; the fixed seat is assembled on the frame and slides along the length direction of the frame.

[0009] Preferably, a tool handle is installed between the amplitude transformer and the electric spindle.

[0010] Preferably, the horn is equipped with an induction device for transmitting electrical signals to the piezoelectric ceramic.

[0011] Preferably, the induction device comprises an induction upper plate and an induction lower plate, the induction upper plate is arranged on a fixed seat for fixing the grinding device, the induction lower plate is assembled on the tool handle, and a gap is provided between the induction upper plate and the induction lower plate.

[0012] Preferably, both the inductive upper plate and the inductive lower plate are provided with ferrite magnetic rings for filtering interference signals.

[0013] Preferably, a clamp device for fixing the induction upper plate is provided between the induction upper plate and the fixing seat.

[0014] Preferably, locking nuts are installed between the horn and the piezoelectric ceramic, and between the horn and the grinding wheel. An operating method of a horn ultrasonic assisted grinding device with a small aspect ratio comprises the following steps:

[0015] S1. Install the grinding wheel on the horn and dress the grinding wheel;

[0016] S2, move the fixed seat along the frame, drive the grinding wheel to move to the workpiece, align the grinding wheel with the workpiece, and return to the original position after completion;

[0017] S3, the grinding device sets the parameters and rotates, the fixed seat moves along the frame to the workpiece, and processes according to the set parameters, and returns to the original position after completion;

[0018] S4. Set the grinding parameters on the ultrasonic generator, turn on the ultrasonic generator, confirm that the grinding wheel achieves high-frequency and slight ultrasonic vibration, process the workpiece according to the set grinding parameters, and return it to its original position after completion.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention discloses an ultrasonic assisted grinding device with a variable amplitude rod having a small aspect ratio. The ultrasonic frequency electrical signal emitted by the ultrasonic generator is received by the piezoelectric ceramic and efficiently converted into mechanical vibration, so that the conversion process is rapid and the energy loss is small, thereby ensuring that the mechanical vibration can be stably and continuously transmitted to the grinding wheel. The mechanical vibration is transmitted to the grinding wheel through the variable amplitude rod, so that the grinding wheel generates high-frequency and micro-amplitude ultrasonic vibrations during the grinding process, which helps to reduce the grinding temperature and significantly improve the grinding efficiency and processing quality, such as reducing surface roughness and improving surface finish.

[0021] Furthermore, the stepped horn helps to enhance the vibration transmission efficiency, reduce energy loss, and improve the stability and uniformity of the mechanical vibration.

[0022] Furthermore, the fixed seat and the frame enable the grinding device to move flexibly, thereby improving the versatility and flexibility of the equipment.

[0023] Furthermore, the design of the tool holder enables the grinding device to be conveniently mounted on the electric spindle, and ensures stability and safety during the machining process.

[0024] Furthermore, the sensing device ensures that the electrical signal is accurately and efficiently transmitted from the ultrasonic generator to the piezoelectric ceramic, thereby converting it into mechanical vibration, thereby improving the response speed and stability of the system.

[0025] Furthermore, the upper and lower induction plates make the transmission of electrical signals more uniform, reduce signal interference and loss, and improve the overall performance of the device. The setting of the gap helps to avoid excessive friction and heat generated by the induction device during vibration, ensuring the long-term stable operation of the device; while transmitting electrical signals during processing, it is not affected by high-speed rotation, effectively avoiding wear of the coil and extending its service life.

[0026] Furthermore, the ferrite ring enables the induction device to efficiently transmit high-frequency electrical signals and filter out interfering signals.

[0027] Furthermore, the clamp device ensures the stability of the induction upper plate during processing and avoids loosening or damage due to vibration.

[0028] Furthermore, the design of the locking nut ensures a tight connection between the components, avoids loosening or falling off during vibration, and ensures stable operation of the device.

[0029] An operating method for an ultrasonic-assisted grinding device with a small aspect ratio horn is provided to improve machining accuracy. In step S1, the grinding wheel is carefully mounted on the horn and necessary dressing is performed. This step ensures that the shape and size of the grinding wheel meet the machining requirements, thereby improving machining accuracy and surface quality; through the tool setting operation in step S2, the grinding wheel can be accurately aligned with the workpiece, providing a reliable basis for subsequent machining. In steps S3 and S4, by setting the parameters of the grinding device and the ultrasonic generator, various factors in the grinding process, such as rotation speed, feed speed, ultrasonic frequency, etc., can be accurately controlled; the grinding efficiency and machining quality are improved, while reducing energy consumption and costs.

[0030] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings:

[0032] Figure 1 It is a schematic diagram of the installation of a small aspect ratio horn ultrasonic assisted grinding device of the present invention;

[0033] Figure 2 for Figure 1 Schematic diagram of the enlarged detail structure in;

[0034] Figure 3 It is a schematic diagram of the structure of the piezoelectric ceramic, horn and grinding wheel of the present invention;

[0035] Figure 4 It is a schematic structural diagram of the grinding device and the tool handle of the present invention;

[0036] Figure 5 is a cross-sectional schematic diagram of the grinding device and the tool handle of the present invention;

[0037] Figure 6 It is a schematic diagram of the location of the nodes in the horn;

[0038] Figure 7 It is a schematic diagram of the position of the antinode in the horn;

[0039] Figure 8 It is an analogy diagram of the circuit diagram of a small aspect ratio horn;

[0040] The following are the descriptions of the reference numerals:

[0041] Ultrasonic generator 1, grinding device 2, piezoelectric ceramic 21, amplitude transformer 22, grinding wheel 23, positioning piece 221, induction device 24, induction upper plate 241, induction lower plate 242, electric spindle 3, fixing seat 4, frame 5, tool handle 31, clamping device 6, locking bolt 61, clamping hoop 62, locking nut 7, sliding connector 8. DETAILED DESCRIPTION

[0042] The technical solutions of the embodiments of the present invention are explained and described below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0043] In the following description, terms such as "inside", "outside", "up", "down", "left", "right", etc. that indicate directions or positional relationships are only used to facilitate the description of the embodiments and simplify the description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operate in a specific direction. Therefore, it should not be understood as a limitation of the present invention.

[0044] like Figures 1 to 5 As shown, a small aspect ratio horn ultrasonic assisted grinding device is mainly composed of an ultrasonic generator 1 and a grinding device 2. The ultrasonic generator 1 is responsible for emitting an electrical signal of ultrasonic frequency, and the ultrasonic generator 1 is connected to the grinding device 2 through the electrical signal. The core components of the grinding device 2 include piezoelectric ceramics 21, a horn 22 and a grinding wheel 23. The piezoelectric ceramics 21 and the grinding wheel 23 are respectively assembled at both ends of the horn 22. When the piezoelectric ceramics 21 receive the electrical signal emitted by the ultrasonic generator 1, the electrical signal is converted into mechanical vibrations through the inverse piezoelectric effect; these vibrations are amplified and transmitted to the grinding wheel 23 through the horn 22, so that the grinding wheel 23 generates high-frequency and micro-amplitude ultrasonic vibrations.

[0045] The ultrasonic frequency electrical signal generated by the ultrasonic generator 1 drives the piezoelectric ceramic 21 to convert into mechanical vibration. This high-frequency vibration can significantly increase the contact frequency between the grinding wheel 23 and the workpiece, thereby completing more grinding actions in the same time and improving the grinding efficiency. The high-frequency micro-amplitude vibration applied to the grinding wheel 23 changes the contact form between the abrasive and the workpiece during the processing from continuous contact processing to "contact-separation-contact-separation" processing. During the processing, the grinding fluid can effectively enter the grinding area, reduce the grinding temperature during the grinding process, and reduce the damage to the processing surface.

[0046] In addition, the device also includes an electric spindle 3, a fixed seat 4 and a frame 5. The electric spindle 3 is wrapped and fixed by the fixed seat 4, and the electric spindle can be moved and adjusted to a certain extent; the speed of the electric spindle is controlled by the grinding machine system and can be set and adjusted within a certain range, which improves the convenience of setting grinding parameters. The grinding device 2 is assembled at the end of the electric spindle 3. The fixed seat 4 can slide along the length direction of the frame 5 to adjust the position of the grinding device 2 and the grinding wheel 23.

[0047] In order to assemble the grinding device 2 more stably, a tool handle 31 is also installed between the amplitude changer 22 and the electric spindle 3. At the same time, in order to ensure that the electrical signal can be stably transmitted to the piezoelectric ceramic 21, the amplitude changer 22 is also equipped with an induction device 24. The induction device 24 is composed of an induction upper disk 241 and an induction lower disk 242. The induction upper disk 241 is arranged on the fixed seat 4, and the induction lower disk 242 is assembled on the tool handle 31. There is a certain gap between the two to achieve non-contact electrical signal transmission. In this embodiment, there is a 1mm gap between the induction upper disk 241 and the induction lower disk 242, which is not affected by high-speed rotation while transmitting electrical signals during the processing process, effectively avoiding the wear of the coil and extending the service life.

[0048] In order to further improve the stability of signal transmission, ferrite rings are also installed in the induction upper plate 241 and the induction lower plate 242 to filter interference signals. The induction upper plate 241 is fixed on the fixing seat 4 through the clamp device 6.

[0049] Locking nuts 7 are installed at the connection between the horn 22 and the piezoelectric ceramic 21 , and at the connection between the horn 22 and the grinding wheel 23 to ensure a tight connection between these components.

[0050] Embodiment 2:

[0051] like Figures 6 to 8 As shown, based on Example 1, this embodiment optimizes the amplitude transformer 22, and reduces the vibration during the rod processing process through a smaller aspect ratio, thereby improving the processing safety. The shape of the middle part of the amplitude transformer 22 is stepped, and the stepped design includes two sections of cylinders with different cross sections, and the position of the variable cross section of the amplitude transformer is located at an odd multiple of 1 / 4 wavelength, that is, at the node, so as to reduce the impact of vibration on the variable cross section of the rod; at the same time, the overall resonant length of the amplitude transformer 22 is configured as a multiple of the half wavelength of the ultrasonic wave, that is, at the antinode, so as to transmit the amplitude to the greatest extent. Therefore, the wavelength calculation formula is used to calculate the wavelength of the amplitude transformer, thereby determining the length of the amplitude transformer.

[0052] The wavelength calculation formula is as follows:

[0053]

[0054] λ--wavelength, v u --wave propagation velocity, f--ultrasonic frequency, E--Young's modulus, ρ--density

[0055] In this embodiment, the material of the horn is 40Cr, the material parameters are shown in the following table, and the frequency of the horn is 32.12kHz. According to the above wavelength calculation formula, the wavelength is about 157mm.

[0056] Material Density (ρ) Young's modulus (E) Poisson's ratio (ν) 40Cr <![CDATA[7.87g / cm 3 ]]> 200GPa 0.24～0.3

[0057] Combined with Newton's second law, the boundary conditions are used to obtain the equation of force and velocity for a single cross-section rod. The force on the horn (F1, F2) and the wave propagation speed in the rod (V1, V2) are analogized to the voltage (U1, U2) and current (I1, I2) in the circuit, and the rod impedance (Z) is analogized to the resistor (Z11, Z12, Z21, Z22), and a force-electric analogy is made for the single cross-section rod. The single cross-section rod is subjected to a circuit equivalent T-shaped transformation, and its impedance is correspondingly transformed into the impedance (ZA, ZB, ZC) under the T-shaped network.

[0058]

[0059] For the variable cross-section stepped rod, a 1:1 transformer is used to connect the step-change cross-section to obtain the impedance equation group of the stepped variable cross-section rod. According to Kirchhoff's law, the equation group is integrated to obtain the frequency equation calculation formula. Combining ultrasonic theory and electromechanical analogy, the size of the variable amplitude rod with a smaller aspect ratio is obtained.

[0060] The piezoelectric ceramic 21 is sleeved outside the horn 22, and the horn 22 is equipped with a positioning member 221 for fixing the knife handle 31. The knife handle 31 and the horn 22 can be connected to each other by welding to ensure stability during rotation.

[0061] Embodiment 3:

[0062] Based on the embodiment 1, the present embodiment optimizes the induction device 24 to further improve the stability of the electric signal transmission. The induction device 24 comprises an induction upper plate 241 and an induction lower plate 242. The induction upper plate 241 is arranged on the fixing seat 4 for fixing the grinding device 2, and the induction upper plate 241 is fixed and does not rotate; the induction lower plate 242 is assembled on the tool handle 31 and rotates with the tool handle 31. A gap is provided between the induction upper plate 241 and the induction lower plate 242.

[0063] The gap between the upper induction plate 241 and the lower induction plate 242 of the induction device 24 is precisely adjusted to ensure the best signal transmission effect. At the same time, the upper induction plate 241 and the lower induction plate 242 are both equipped with ferrite rings for filtering interference signals; the ferrite rings can effectively filter interference signals.

[0064] In addition, a clamping device 6 for fixing the induction upper plate 241 is provided between the induction upper plate 241 and the fixing seat 4. The structure of the clamping device 6 is also improved, so that it can fix the induction upper plate 241 more firmly to prevent it from loosening or displacement during processing.

[0065] Embodiment 4:

[0066] An operating method of a small aspect ratio horn ultrasonic assisted grinding device comprises the following steps:

[0067] S1, installing the grinding wheel 23 on the horn 22, and dressing the grinding wheel 23;

[0068] S2, the fixed seat 4 is moved along the frame 5, driving the grinding wheel 23 to move to the workpiece, the grinding wheel 23 and the workpiece are aligned, and then return to the original position after completion;

[0069] S3, the grinding device 2 sets the parameters and rotates, the fixed seat 4 moves along the frame 5 to the workpiece, and processes according to the set parameters, and returns to the original position after completion;

[0070] S4, setting grinding parameters on the ultrasonic generator 1, turning on the ultrasonic generator 1, confirming that the grinding wheel 23 realizes high-frequency and slight-amplitude ultrasonic vibration, processing the workpiece according to the set grinding parameters, and returning to the original position after completion.

[0071] The workpiece of this embodiment is the outer ring of the deep groove ball bearing 6303, and the processing object is its inner groove surface. The grinding wheel is a 100 mesh (150μm) ceramic bond chrome corundum grinding wheel, the workpiece speed is 200rpm, the grinding wheel speed is 10000rpm, the feed speed is 0.05mm / min, and the grinding depth is 80μm. Under the above grinding conditions, the bearing ring is ground and the workpiece processing under ordinary grinding and ultrasonic vibration assisted grinding conditions are compared; before grinding, the roughness and roundness of the inner groove of the ring are tested, and 5 bearing rings are taken, and 5 different positions of each ring are measured to take the average value; the roughness of the inner groove of the ring is measured by PGI830 roughness profiler; the roundness of the inner groove of the ring is measured by Talyrond565 roundness meter; the average roughness of the inner groove of the ring before grinding is measured to be between 0.35564μm and 0.3956 6μm, and the average roundness is between 27.31μm and 31.05μm; after ordinary grinding, the best roughness of the inner groove of the ring is 0.2662μm, the overall average roughness is 0.28004μm, the best roundness is 23.76μm, and the overall average roundness is 24.174μm; after ultrasonic vibration assisted grinding, the best roughness of the inner groove of the ring is 0.2056μm, the overall average roughness is 0.22024μm, the best roundness is 21.85μm, and the overall average roundness is 22.168μm. Under the same experimental conditions, the ring processed by ultrasonic vibration assisted grinding has better surface roughness and roundness, which has certain advantages over ordinary grinding.

[0072] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. An ultrasonic assisted grinding device with a small aspect ratio horn, characterized in that: The invention comprises an ultrasonic generator (1) and a grinding device (2); the ultrasonic generator (1) is used to emit an electric signal of an ultrasonic frequency and is connected to the electric signal of the grinding device (2); the grinding device (2) comprises a piezoelectric ceramic (21), a horn (22) and a grinding wheel (23); the piezoelectric ceramic (21) and the grinding wheel (23) are assembled at both ends of the horn (22); the piezoelectric ceramic (21) is used to receive the electric signal emitted by the ultrasonic generator (1) and convert it into mechanical vibration, and the mechanical vibration is transmitted to the grinding wheel (23) through the horn (22).

2. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 1, characterized in that: The middle portion of the horn (22) is in a stepped shape.

3. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 1, characterized in that: It also comprises an electric spindle (3), a fixed seat (4) and a frame (5); the electric spindle (3) is wrapped and fixed by the fixed seat (4); the grinding device (2) is assembled on the electric spindle (3); the fixed seat (4) is assembled on the frame (5) and slides along the length direction of the frame (5).

4. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 3, characterized in that: A tool handle (31) is installed between the amplitude change rod (22) and the electric spindle (3).

5. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 4, characterized in that: The horn (22) is equipped with an induction device (24) for transmitting an electrical signal to the piezoelectric ceramic (21).

6. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 5, characterized in that: The induction device (24) comprises an induction upper plate (241) and an induction lower plate (242); the induction upper plate (241) is arranged on a fixing seat (4) for fixing the grinding device (2); the induction lower plate (242) is mounted on a tool handle (31); and a gap is provided between the induction upper plate (241) and the induction lower plate (242).

7. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 6, characterized in that: The inductive upper plate (241) and the inductive lower plate (242) are both provided with ferrite magnetic rings for filtering interference signals.

8. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 6, characterized in that: A clamp device (6) for fixing the induction upper plate (241) is provided between the induction upper plate (241) and the fixing seat (4).

9. The ultrasonic assisted grinding device with a small aspect ratio horn according to claim 1, characterized in that: Locking nuts (7) are installed between the horn (22) and the piezoelectric ceramic (21), and between the horn (22) and the grinding wheel (23).

10. An operating method of a small aspect ratio horn ultrasonic assisted grinding device, characterized in that: A small aspect ratio horn ultrasonic assisted grinding device applicable to any one of claims 1 to 9, comprising the following steps: S1, installing the grinding wheel (23) on the horn (22), and dressing the grinding wheel (23); S2, the fixed seat (4) is moved along the frame (5), driving the grinding wheel (23) to move to the workpiece, the grinding wheel (23) and the workpiece are aligned, and then return to the original position after completion; S3, the grinding device (2) sets the parameters and rotates, the fixed seat (4) moves along the frame (5) to the workpiece, performs processing according to the set parameters, and returns to the original position after completion; S4, setting grinding parameters on the ultrasonic generator (1), turning on the ultrasonic generator (1), confirming that the grinding wheel (23) achieves high-frequency and slight-amplitude ultrasonic vibration, processing the workpiece according to the set grinding parameters, and returning to the original position after completion.

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