CN113334648B - High-frequency elliptical vibration cutting system and method - Google Patents
High-frequency elliptical vibration cutting system and method Download PDFInfo
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- CN113334648B CN113334648B CN202110592988.5A CN202110592988A CN113334648B CN 113334648 B CN113334648 B CN 113334648B CN 202110592988 A CN202110592988 A CN 202110592988A CN 113334648 B CN113334648 B CN 113334648B
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- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 claims description 5
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
- B29C33/3842—Manufacturing moulds, e.g. shaping the mould surface by machining
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B3/00—Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D79/00—Methods, machines, or devices not covered elsewhere, for working metal by removal of material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/50—Application to a particular transducer type
- B06B2201/55—Piezoelectric transducer
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Abstract
The invention provides a high-frequency elliptical vibration cutting system and a high-frequency elliptical vibration cutting method, which belong to the field of ultra-precision machining and comprise an ultrasonic power supply, a power amplifier and an elliptical vibrator which are sequentially connected; the ultrasonic power supply is used for generating two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency; the power amplifier is used for receiving and gaining and amplifying the power of the two paths of high-frequency sinusoidal alternating-current electric signals and respectively outputting a bending vibration excitation electric signal and a longitudinal vibration excitation electric signal; the elliptical vibrator is used for converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal and realizing high-frequency elliptical vibration under the composite vibration of the bending vibration signal and the longitudinal vibration signal; the resonance frequency of the second-order longitudinal vibration mode is consistent with that of the fourth-order bending vibration mode, and the second-order longitudinal vibration mode and the fourth-order bending vibration mode have two superposed standing wave nodes; and the standing wave node is used as a mounting support point. The invention improves the stability of the high-frequency elliptical vibration of the elliptical vibrator.
Description
Technical Field
The invention belongs to the field of ultra-precision machining, and particularly relates to a high-frequency elliptical vibration cutting system and method.
Background
In recent years, with the continuous progress and rapid development of the technological level, in many fields such as optical engineering, aerospace field, digital storage and biomedicine, the demand for optical elements having a complex curved surface and high-quality microstructures and high-service performance is increasing, and thus the processing accuracy and quality required in these fields are becoming more and more severe.
Most optical elements or injection molds for optical elements are generally made from various difficult-to-machine materials with poor machinability, such as: hard and brittle materials such as optical glass, silicon carbide, monocrystalline silicon and ceramics, hard alloys such as tungsten carbide and titanium carbide, and ferrous metals such as die steel and stainless steel. Meanwhile, in the cutting process of the optical element or the injection mold of the optical element, a plurality of processing defects such as serious cutter abrasion, fracture damage and the like can be generated, so that the processing precision and the surface quality are rapidly deteriorated, and the application expansion of the optical element or the injection mold in the ultra-precision manufacturing of the optical element is further restricted. Therefore, the traditional machining mode is far from meeting the machining requirement of the performance of modern parts.
The ultrasonic elliptical vibration cutting technology is created for realizing ultrahigh precision and extremely low damage surface of an optical element made of a difficult-to-machine material with high efficiency, high precision and low cost, and the cutting process is fundamentally changed by adding elliptical track motion on a cutter, so that the ultra-precision machining of the difficult-to-machine material can be realized.
However, the existing ultrasonic vibration auxiliary cutting device has the defects of low working frequency, poor cutting stability, complex device structure, low practicability and the like, for example, the working frequency is difficult to break through 40kHz, so that the cutting efficiency is low, the existing ultrasonic vibration auxiliary cutting device mostly adopts single-stagnation-point support, and is difficult to provide reliable support for a high-frequency vibration device, so that the working stability of the device is poor.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a high-frequency elliptical vibration cutting system and method, and aims to solve the problem that the stability of the whole vibrator is poor due to the fact that a stagnation point supporting method adopted by the existing high-frequency elliptical vibration cutting device cannot provide reliable support for an elliptical vibrator.
In order to achieve the above objects, in one aspect, the present invention provides a high-frequency elliptical vibration cutting system, comprising an ultrasonic power supply, a power amplifier and an elliptical vibrator, which are connected in sequence;
the ultrasonic power supply is used for generating two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency; wherein, the frequency of the high-frequency sine alternating current signal is consistent with the working frequency of the elliptical vibrator;
the power amplifier comprises a bending vibration power amplifier and a longitudinal vibration power amplifier, the cathodes of the bending vibration power amplifier and the longitudinal vibration power amplifier are connected in series and used for receiving and gaining the power of the two paths of high-frequency sinusoidal alternating current signals and respectively outputting a bending vibration excitation electrical signal and a longitudinal vibration excitation electrical signal;
the elliptical vibrator is used for converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group respectively, and realizing high-frequency elliptical vibration under the composite vibration of the bending vibration signal and the longitudinal vibration signal;
the resonance frequency of the second-order longitudinal vibration mode is consistent with that of the fourth-order bending vibration mode, and the second-order longitudinal vibration mode and the fourth-order bending vibration mode have two coincident standing wave nodes; and the standing wave node is used as a mounting support point.
Preferably, the high-frequency elliptical vibration cutting system further comprises a controller, wherein the input end of the controller is connected with the elliptical vibrator, and the output end of the controller is connected with the ultrasonic power supply;
the method is used for determining the resonance working point of the elliptical vibrator by analyzing the real-time amplitude change and phase change of the current of the elliptical vibrator, performing impedance matching in the cutting process, changing the output voltage of the ultrasonic power supply according to the load change, and ensuring that the working frequency is stable and the amplitude is kept unchanged.
Preferably, the elliptical vibrator comprises a diamond cutter, an ultrasonic transducer, a fastening bolt, a packaging shell and a DB9 interface;
the diamond cutter is arranged in a cutter containing groove at the output end of the ultrasonic transducer; the ultrasonic transducer is used for converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group respectively, working in a second-order longitudinal vibration mode and a fourth-order bending vibration mode, realizing the mode degeneracy of the two vibration modes, having two superposed standing wave nodes, and being provided with a standing point mounting hole at the standing wave node;
the fastening bolt is used for supporting the threaded hole through the stagnation point, jacking the threaded hole to the stagnation point mounting hole and fastening the ultrasonic transducer in the packaging shell;
the packaging shell is used for processing stagnation point supporting threaded holes on two sides for stagnation point supporting, and slotted holes are formed in the front part and the rear part and used for the penetration and fixation of the ultrasonic transducer and a DB9 interface; one side of the packaging shell close to the diamond cutter is a front part, and one side close to the DB9 interface is a rear part;
the DB9 interface is installed on the packaging shell and is used for being connected with the ultrasonic transducer through a lead, and the power amplifier is connected with the male connector of the output line DB9 of the power amplifier.
Preferably, the ultrasonic transducer comprises an ultrasonic amplitude transformer, a piezoelectric ceramic group, an end cover and a piezoelectric detection element;
the ultrasonic amplitude transformer and the piezoelectric ceramic group are of a hollow structure, the end cover is of a stepped structure, a thread is processed at the end with a small area, a stagnation point mounting hole is formed at the end with a large area, and the ultrasonic amplitude transformer and the piezoelectric ceramic group are fixed in a nested manner by using the end cover; the ultrasonic amplitude transformer is in a stepped amplitude transformer structure with a conical section transition, and the output end of the ultrasonic amplitude transformer is provided with a tool accommodating groove; a standing point mounting hole is formed in the conical part of the bracket; the piezoelectric detection element is positioned between the tool containing groove and the conical part of the ultrasonic amplitude transformer and comprises two semicircular piezoelectric materials; the end cover is provided with another stagnation point mounting hole;
the piezoelectric ceramic group comprises a longitudinal vibration piezoelectric ceramic group, a bending vibration piezoelectric ceramic group and an electrode plate; the longitudinal vibration piezoelectric ceramic group comprises n whole circular ring piezoelectric ceramics, electrode plates are arranged on two staggered sides between every two adjacent circular ring piezoelectric ceramics, and n +1 electrode plates are provided in total; the bending vibration piezoelectric ceramic group comprises m semicircular ring piezoelectric ceramics, each two semicircular ring piezoelectric ceramics form a whole circular ring piezoelectric ceramic, electrode plates are arranged on two staggered sides between every two adjacent whole circular ring piezoelectric ceramics, and m/2+1 electrode plates are provided; the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group share one electrode plate; two adjacent circular ring piezoelectric ceramics of the longitudinal vibration piezoelectric ceramic group are polarized in opposite directions; each semicircular ring piezoelectric ceramic in the bending vibration piezoelectric ceramic group is polarized in the opposite direction with the adjacent semicircular ring piezoelectric ceramic; the electrode plates on the same side as the electrode plates on the edge side of the piezoelectric ceramic group are connected with the common cathodes of the two power amplifiers; the electrode sheet on the opposite side of the edge side electrode sheet in the longitudinal vibration piezoelectric ceramic group is connected with the anode of a longitudinal vibration power amplifier; the electrode plate on the opposite side of the edge side electrode plate in the bending vibration piezoelectric ceramic group is connected with the anode of a bending vibration power amplifier;
the electrode plate is used for respectively transmitting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal to the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the piezoelectric ceramic group is used for converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal, and realizing high-frequency elliptical vibration of the diamond cutter under the composite vibration of the bending vibration signal and the longitudinal vibration signal; the stagnation point mounting hole on the end cover, the cutting line of the bending vibration piezoelectric ceramic group, the stagnation point mounting hole on the ultrasonic amplitude transformer and the cutter containing groove on the ultrasonic amplitude transformer are positioned on the same bus;
the resonance frequencies of the second-order longitudinal vibration mode and the fourth-order bending vibration mode are consistent, and two coincident standing wave nodes are shared.
Preferably, the controller comprises a main control CPU unit, a current sampling detection circuit and a power control circuit;
the current sampling detection circuit is used for receiving a current signal transmitted by a piezoelectric detection element in the elliptical vibrator; the main control CPU unit is used for analyzing the current change and the phase difference of two semicircular ring piezoelectric materials in the piezoelectric detection element, determining the resonance working point of the output end of the elliptical vibrator, and changing the amplitude of a high-frequency sinusoidal alternating current signal output by the ultrasonic power supply according to the load change;
the power control circuit is used for impedance matching in the cutting process under the control of the main control CPU unit, and stabilizing the resonant frequency in the cutting process.
Preferably, the fastening bolt is a ball head fastening bolt, the inner hexagon is provided with no head part, and the end part is a ball head.
Preferably, the piezoelectric ceramic group is lead zirconate titanate piezoelectric ceramic.
On the other hand, based on the high-frequency elliptical vibration cutting system provided by the invention, the invention provides a corresponding cutting method, which comprises the following steps:
two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency are gained by bending vibration excitation electric signals and longitudinal vibration excitation electric signals;
respectively converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the bending vibration signal and the longitudinal vibration signal jointly drive the elliptical vibrator to vibrate, so that high-frequency elliptical vibration is realized;
the resonance frequency of the second-order longitudinal vibration mode generated by the elliptical vibrator driven by the longitudinal vibration signal is consistent with the resonance frequency of the fourth-order bending vibration mode generated by the elliptical vibrator driven by the bending vibration signal, two coincident standing wave nodes are shared, and the standing wave nodes are used as supporting points for mounting the elliptical vibrator.
Preferably, the invention provides a high-frequency elliptical vibration cutting system, further comprising the following steps:
detecting a current signal of the elliptical vibrator in the vibration process by using a piezoelectric detection element;
analyzing the change and the phase difference of the current signals, and determining the resonance working point of the elliptical vibrator;
continuously performing impedance matching in the cutting process, and stabilizing the resonant frequency in the cutting process;
and changing the amplitude of the high-frequency sinusoidal alternating current signal according to the load change.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
the invention provides an elliptical vibrator supported by double stagnation point nodes, which is supported by bolts, namely point contact, and has small influence on the vibration characteristic of the elliptical vibrator, thereby improving the rigidity of the whole elliptical vibrator and improving the stability of high-frequency elliptical vibration of the elliptical vibrator.
The elliptical vibrator works in the axial direction and the bending direction of the ultrasonic transducer, so that the formed ellipse is a normal surface ellipse, and the efficient intermittent removal of workpiece materials is more favorably realized in the actual processing process. The elliptical vibrator provided by the invention works in a composite vibration mode of second-order longitudinal vibration and fourth-order bending vibration, can realize mode degeneracy, has the working frequency of 40kHz, and greatly improves the material removal efficiency and the processing quality over the existing structure.
According to the fixing of the packaging shell, the ball head fastening bolt and two standing wave nodes of the ultrasonic transducer can be assembled through the two standing point mounting threaded holes of the packaging shell, so that the bolt can be effectively prevented from loosening in the cutting process, the matching of the ball head fastening bolt and the ultrasonic transducer can be improved, the modal vibration mode of the ultrasonic transducer cannot be damaged, and the stability of the ultrasonic transducer is improved.
In the invention, the diamond cutter is arranged at the output end of an ultrasonic amplitude transformer of an ultrasonic transducer, the diamond cutter is designed according to the structure of the output end of the ultrasonic amplitude transformer, and is arranged at the output end through a small screw in a pre-tightening manner in the practical application process, so that the diamond cutter can generate high-frequency elliptical vibration when an elliptical vibrator vibrates at high frequency, and the elliptical vibration cutting processing of a processing material is realized.
The ultrasonic amplitude transformer can be selected according to actual requirements, such as a conical rod, a stepped rod, a Betzer curve rod and the like.
The ultrasonic amplitude transformer and the end cover are made of stainless steel materials with excellent mechanical properties, and the physical properties such as density and hardness are close to those of piezoelectric ceramics, so that the overall properties of the ultrasonic transducer are close, the heat conduction is close to the same, the local concentration of heat generated during processing is avoided, and the design of the overall ultrasonic transducer is facilitated.
The piezoelectric ceramic group adopts the whole circular ring piezoelectric ceramic which is made of lead zirconate titanate piezoelectric ceramic, the output power is high, and the ceramic is polarized along the thickness direction; the piezoelectric ceramic group vibrates along the axial direction of the ultrasonic transducer, the bending vibration piezoelectric ceramic group is cut into paired semicircular piezoelectric ceramics in half, and the semicircular piezoelectric ceramics are combined and installed together after the direction is turned over, so that each piece of combined ceramics expands and contracts in half under the action of an electric field, and the ultrasonic amplitude transformer vibrates along the bending direction; the longitudinal vibration ceramic group and the bending vibration ceramic group are assembled together without separation, so that the whole transducer structure is more compact, and meanwhile, longitudinal and bending composite vibration can be generated, and a diamond cutter arranged at the output end of the ultrasonic amplitude transformer generates elliptic track vibration.
The piezoelectric detection element of the invention is composed of two semicircular polyvinylidene fluoride piezoelectric materials, has the characteristics of quick response, high sensitivity and wide pressure measuring range, when the ultrasonic transducer generates high-frequency vibration, the piezoelectric detection element generates corresponding deformation, based on the positive piezoelectric effect, high-frequency dynamic current can be generated at two sides of the piezoelectric detection element, because the ultrasonic transducer generates longitudinal bending composite vibration, the charge variation generated by the longitudinal bending deformation of the two semicircular piezoelectric detection elements is different, two different dynamic currents can be generated, the current is detected by a controller current sampling detection circuit and then processed by a main control CPU unit, the sum of the two current variations is current response generated by longitudinal vibration, the difference of the two current variations is current response generated by bending vibration, and based on the corresponding relation between the current response and the amplitude of an output end, impedance matching is carried out by regulating and controlling the power control circuit, and the output voltage of the ultrasonic power supply is regulated to carry out feedback control, so that the elliptical vibrator is ensured to generate stable elliptical track vibration.
Drawings
FIG. 1 is a block diagram of an elliptical vibratory cutting system provided in accordance with an embodiment of the present invention;
FIG. 2 is a diagram illustrating an overall physical structure of the elliptical vibration cutting system according to the embodiment of the present invention;
FIG. 3 is a diagram of an elliptical vibrator according to an embodiment of the present invention;
FIG. 4 is a block diagram of an elliptical vibrator package structure according to an embodiment of the present invention;
FIG. 5 is a three-dimensional block diagram of an ultrasound transducer provided by an embodiment of the present invention;
FIG. 6 is a diagram of an ultrasonic transducer mode and two-dimensional assembly according to an embodiment of the present invention;
FIG. 7 is a wiring diagram of an ultrasound transducer provided by an embodiment of the present invention interfacing with DB 9;
fig. 8 is a wiring diagram between an electrode pad and a power amplifier provided in an embodiment of the present invention;
FIG. 9 is a diagram illustrating a process for assembling a piezoelectric ceramic assembly according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a piezoelectric sensing element provided in accordance with an embodiment of the present invention;
FIG. 11 is a test chart of the vibration trace of the blade tip provided by the embodiment of the invention;
the same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:
a-an ultrasonic power supply; a B-power amplifier; a C-elliptical vibrator; c1-diamond tool; c2-ultrasonic transducer; c3-ball stud; c4-package housing; a C5-DB9 interface (female port); c201-ultrasonic amplitude transformer; c202-piezoelectric ceramic group; c202 a-bending vibration ceramic group; c202 b-longitudinally vibrating ceramic group; C202C, electrode sheet; c203-end cap; c204-piezoelectric detection element; and D-a controller.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In one aspect, as shown in fig. 1 and 2, the present invention provides a high-frequency elliptical vibration cutting system, comprising an ultrasonic power supply, a power amplifier and an elliptical vibrator, which are connected in sequence;
the ultrasonic power supply is used for generating two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency; wherein, the frequency of the high-frequency sine alternating current signal is consistent with the working frequency of the elliptical vibrator;
the power amplifier comprises a bending vibration power amplifier and a longitudinal vibration power amplifier, the cathodes of the bending vibration power amplifier and the longitudinal vibration power amplifier are connected in series and used for receiving and gaining the power of the two paths of high-frequency sinusoidal alternating current signals and respectively outputting a bending vibration excitation electrical signal and a longitudinal vibration excitation electrical signal;
the elliptical vibrator is used for converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group respectively, and realizing high-frequency elliptical vibration under the composite vibration of the bending vibration signal and the longitudinal vibration signal;
the resonance frequency of the second-order longitudinal vibration mode is consistent with that of the fourth-order bending vibration mode, and the second-order longitudinal vibration mode and the fourth-order bending vibration mode have two coincident standing wave nodes; and the standing wave node is used as a mounting support point.
Preferably, as shown in fig. 1 and fig. 2, the high-frequency elliptical vibration cutting system further comprises a controller, wherein an input end of the controller is connected with the elliptical vibrator, and an output end of the controller is connected with the ultrasonic power supply;
the method is used for determining the resonance working point of the elliptical vibrator by analyzing the real-time amplitude change and phase change of the current of the elliptical vibrator, performing impedance matching in the cutting process, changing the output voltage of the ultrasonic power supply according to the load change, and ensuring that the working frequency is stable and the amplitude is kept unchanged.
Preferably, as shown in fig. 2 and 3, the elliptical vibrator includes a diamond cutter, an ultrasonic transducer, a fastening bolt, a package housing, and a DB9 interface;
the diamond cutter is arranged in a cutter containing groove at the output end of the ultrasonic transducer; the ultrasonic transducer is used for converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group respectively, working in a second-order longitudinal vibration mode and a fourth-order bending vibration mode, realizing mode degeneracy of the two vibration modes, having two superposed standing wave nodes, and being provided with a standing point mounting hole at the standing wave node, as shown in fig. 6;
as shown in fig. 4, the fastening bolt is used for supporting the threaded hole through the stagnation point, propping up to the stagnation point mounting hole, and fastening the ultrasonic transducer in the packaging shell;
the packaging shell is used for processing stagnation point supporting threaded holes on two sides for stagnation point supporting, and slotted holes are formed in the front and back parts for the ultrasonic transducer and the DB9 interface to penetrate and fix; one side of the packaging shell close to the diamond cutter is a front part, and one side close to the DB9 interface is a rear part;
as shown in fig. 7, a DB9 interface is mounted on the package housing for connection to the ultrasonic transducer by wires and to the power amplifier by a power amplifier output line DB9 male.
Preferably, as shown in fig. 5, the ultrasonic transducer comprises an ultrasonic horn, a piezoelectric ceramic group, an end cap and a piezoelectric detection element;
the ultrasonic amplitude transformer and the piezoelectric ceramic group are hollow structures, the end cover is of a stepped structure, a thread is processed at one end with a small area, a stagnation point mounting hole is formed at one end with a large area, and the ultrasonic amplitude transformer and the piezoelectric ceramic group are fixed by nesting the end cover; the ultrasonic amplitude transformer is in a stepped amplitude transformer structure with a conical section transition, and the output end of the ultrasonic amplitude transformer is provided with a tool accommodating groove; a standing point mounting hole is formed in the conical part of the bracket; the piezoelectric detection element is positioned between the tool containing groove and the conical part of the ultrasonic amplitude transformer and comprises two semicircular piezoelectric materials; the end cover is provided with another stagnation point mounting hole;
as shown in fig. 8 and 9, the piezoelectric ceramic group includes a longitudinal vibration piezoelectric ceramic group, a bending vibration piezoelectric ceramic group, and electrode pieces; the longitudinal vibration piezoelectric ceramic group comprises n whole circular ring piezoelectric ceramics, electrode plates are arranged on two staggered sides of every two adjacent circular ring piezoelectric ceramics, and n +1 electrode plates are provided in total; the bending vibration piezoelectric ceramic group comprises m semicircular piezoelectric ceramics, each two semicircular piezoelectric ceramics form a whole circular piezoelectric ceramic, electrode plates are arranged on two staggered sides between every two adjacent whole circular piezoelectric ceramics, and m/2+1 electrode plates are provided; the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group share one electrode plate; the two adjacent ring piezoelectric ceramics of the longitudinal vibration piezoelectric ceramic group are polarized in opposite directions; each semicircular ring piezoelectric ceramic in the bending vibration piezoelectric ceramic group is polarized in the opposite direction to the adjacent semicircular ring piezoelectric ceramic; the electrode plates on the same side as the electrode plates on the edge side of the piezoelectric ceramic group are connected with the common cathodes of the two power amplifiers; the electrode plate on the opposite side of the edge side electrode plate in the longitudinal vibration piezoelectric ceramic group is connected with the anode of a longitudinal vibration power amplifier; the electrode plate on the opposite side of the electrode plate on the edge side in the bending vibration piezoelectric ceramic group is connected with the anode of a bending vibration power amplifier;
the electrode plate is used for respectively transmitting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal to the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the piezoelectric ceramic group is used for converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal, and under the composite vibration of the bending vibration signal and the longitudinal vibration signal, as shown in fig. 11, the high-frequency elliptic vibration of the diamond cutter is realized; the stagnation point mounting hole on the end cover, the cutting line of the bending vibration piezoelectric ceramic group, the stagnation point mounting hole on the ultrasonic amplitude transformer and the cutter installing groove on the ultrasonic amplitude transformer are positioned on the same bus;
the resonance frequencies of the second-order longitudinal vibration mode and the fourth-order bending vibration mode are consistent, and two coincident standing wave nodes are shared.
Preferably, the controller comprises a main control CPU unit, a current sampling detection circuit and a power control circuit;
the current sampling detection circuit is used for receiving a current signal transmitted by a voltage detection element in the elliptical vibrator; the main control CPU unit is used for analyzing the current change and the phase difference of two semicircular ring piezoelectric materials in the piezoelectric detection element, determining the resonance working point of the output end of the elliptical vibrator, and changing the amplitude of a high-frequency sinusoidal alternating current signal output by the ultrasonic power supply according to the load change; the power control circuit is used for impedance matching in the cutting process under the control of the main control CPU unit, and stabilizing the resonant frequency in the cutting process.
Preferably, the fastening bolt is a ball head fastening bolt, the inner hexagon is provided with no head part, and the end part is a ball head.
Preferably, the piezoelectric ceramic group is lead zirconate titanate piezoelectric ceramic.
On the other hand, based on the high-frequency elliptical vibration cutting system provided by the invention, the invention provides a corresponding cutting method, which comprises the following steps:
two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency are gained by bending vibration excitation electric signals and longitudinal vibration excitation electric signals;
respectively converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the bending vibration signal and the longitudinal vibration signal jointly drive the elliptical vibrator to vibrate, so that high-frequency elliptical vibration is realized;
the resonance frequency of the second-order longitudinal vibration mode generated by the elliptical vibrator driven by the longitudinal vibration signal is consistent with the resonance frequency of the fourth-order bending vibration mode generated by the elliptical vibrator driven by the bending vibration signal, two superposed standing wave nodes are shared, and the standing wave nodes are used as supporting points for mounting the elliptical vibrator.
Preferably, the invention provides a high-frequency elliptical vibration cutting system, which further comprises the following steps:
detecting a current signal of the elliptical vibrator in the vibration process by using a piezoelectric detection element;
analyzing the change and the phase difference of the current signals, and determining the resonance working point of the elliptical vibrator;
continuously performing impedance matching in the cutting process, and stabilizing the resonant frequency in the cutting process;
and changing the amplitude of the high-frequency sinusoidal alternating current signal according to the load change. Examples
As shown in fig. 1 and 2, the present invention provides a super-elliptical vibration cutting system, comprising:
the ultrasonic power supply A is used for generating two paths of high-frequency sinusoidal alternating current signals with adjustable signal amplitude and frequency numerical control; the amplitude and the frequency of the two paths of electric signals can be independently regulated, the frequency of the output signal is consistent with the working frequency of the elliptical vibrator, the phase difference of the two paths of signals can be accurately regulated and controlled in real time based on a common time base circuit in the ultrasonic power supply A, the stable high-frequency sinusoidal electric signal is input to the power amplifier B, and the size and the phase of an elliptical vibration track generated by the elliptical vibrator C are regulated and controlled;
the number of the power amplifiers B is two, the power amplifiers B are independently controlled and are respectively used for exciting longitudinal vibration and bending vibration, and the cathodes of the two power amplifiers are connected in series; in order to adjust the excitation signal input to the elliptical vibrator conveniently, the gain times of the two power amplifiers are adjusted to be maximum and are kept unchanged, the power amplifiers can amplify the high-frequency sinusoidal electrical signals transmitted by the ultrasonic power supply into electrical signals required by the elliptical vibrator C in a gain mode, and the two electrical signals are respectively transmitted to the bending vibration piezoelectric ceramic group C202a and the longitudinal vibration piezoelectric ceramic group C202b of the elliptical vibrator C, so that the elliptical vibrator C is driven to generate elliptical track vibration;
as shown in fig. 1, the controller D includes a main control CPU unit, a current sampling detection circuit, and a power control circuit; when the elliptical vibration cutting system is started, a power control circuit in the controller D can sweep frequency; the current sampling detection circuit receives a current signal transmitted by the piezoelectric detection element of the elliptical vibrator, analyzes the current change and the phase difference of the two piezoelectric detection elements through the main control CPU unit, determines the resonance working point of the vibrator at the output end of the elliptical vibrator C, and controls the ultrasonic power supply A to output a high-frequency electric signal with corresponding frequency; when cutting is carried out, the main control CPU unit analyzes and detects real-time amplitude change and phase change of current, impedance matching is carried out in the cutting process through the control power control circuit, the output voltage of the ultrasonic power supply is changed according to load change, the working frequency is guaranteed to be stable, the amplitude is kept unchanged, and therefore the diamond tool C1 at the output end of the elliptical vibrator C generates elliptical vibration with stable track, and the processing quality is guaranteed;
the elliptical vibrator C is an output unit of the elliptical vibration cutting system, works in a second-order longitudinal vibration mode and a fourth-order bending vibration mode, achieves mode degeneracy and consistent resonance frequency in the two working modes, and is provided with two superposed standing wave nodes serving as mounting support points; under the action of excitation signals transmitted by the ultrasonic power supply A and the power amplifier B, high-frequency vibration with controllable amplitude and phase can be generated;
as shown in fig. 2 and 3, the elliptical vibrator C includes a diamond cutter C1, an ultrasonic transducer C2, a ball head fastening bolt C3, a package housing C4 and a DB9 interface C5 (female port);
the diamond cutter C1 is installed in a notch of the output end of the ultrasonic transducer C2, the bottom surface of the diamond cutter C1 is in close contact with the lower surface of the notch of the ultrasonic transducer C2, the diamond cutter C1 and the ultrasonic transducer C2 form a unified whole and resonate together at the working frequency when the ultrasonic transducer C2 vibrates at high frequency, and the ultrasonic transducer C2 transmits second-order longitudinal vibration and fourth-order bending vibration to the diamond cutter C1 to drive the diamond cutter C1 to generate elliptic-track vibration;
the ultrasonic transducer C2 is shown in FIGS. 5 and 6 and comprises an ultrasonic horn C201, a piezoelectric ceramic group C202, an end cover C203 and a piezoelectric detection element C204; the ultrasonic transducer C2 works in a second-order longitudinal vibration mode and a fourth-order bending vibration mode, mode degeneracy of the two vibration modes is realized, the resonant frequency is 40kHz, two superposed standing wave nodes are provided, fastening and supporting are carried out through a ball head fastening bolt C3, resonance is generated under excitation of a high-frequency electric signal, and then elliptic track vibration is generated at an output end;
as shown in fig. 4, the ball head fastening bolt C3 has no head in the hexagon socket, the end is a ball head, and the two pairs of ball head fastening bolts are tightly screwed with the tight screw-thread of the standing point supporting screw hole of the packaging shell C4 through the screw thread on the bolt, so that the two pairs of standing point mounting holes of the ultrasonic transducer C2 can be tightly pressed in one step, because the end of the ball head fastening bolt C3 is a ball head, the contact with the ultrasonic transducer C2 is a spherical contact, the point contact is more stable and firm than the point contact, and the supporting part is the standing point of the ultrasonic transducer C2, the working mode vibration mode of the ultrasonic transducer cannot be damaged, and the ball head fastening bolt C3 is more stable than the single standing point support and more suitable for high-frequency large amplitude;
the packaging shell C4 is provided with M5 threaded holes with specific distances at two sides for standing point support, and is provided with slotted holes at the front and the rear for the penetration and fixation of the ultrasonic transducer C2 and the DB9 interface C5;
the DB9 interface C5 is a DB9 female port, as shown in fig. 7 and fig. 2, the DB9 interface C5 is connected with an electrode plate C202C of a piezoelectric ceramic group C202 through a lead, then the DB9 female port is installed on a packaging shell C4 and is connected with the electrode plate C202 through a power amplifier B output line DB9 male head, so that the electrode plate C202C of the piezoelectric ceramic group can be effectively prevented from being pulled, the tensile stress is eliminated, and poor contact of the electrode plate C202C and lead fracture are avoided;
as shown in fig. 5 to 9, as shown in fig. 5, the ultrasonic transducer C2 includes an ultrasonic horn C201, a piezoelectric ceramic group C202, an end cap C203, and a piezoelectric detection element C205; the difficulty in manufacturing the ultrasonic transducer C2 lies in the mode degeneracy, assembly and support installation, the ultrasonic transducer C2 of the present invention operates in the second-order longitudinal vibration mode and the fourth-order bending vibration mode, the resonant frequencies are the same, as shown in fig. 5, the two mode modes have two coincident stagnation points for installation and support, and the present invention has practical applicability, and simultaneously, the present invention also considers the problems of assembly and support, which are described in detail below:
the ultrasonic amplitude transformer C201 is made of stainless steel materials, has excellent comprehensive mechanical properties, can effectively amplify vibration by adopting a stepped deformation amplitude transformer structure with a conical section transition, is provided with a tool containing groove at the output end for installing a diamond cutter C1, is internally provided with a threaded hole for being in threaded fit connection with an end cover, is provided with a stagnation point installation hole at the conical part, and is provided with a platform at one end with a large radius, so that the ultrasonic amplitude transformer C201 can be stably clamped and kept in a fixed position when the whole ultrasonic transducer C2 is assembled;
as shown in fig. 6 and 8, the piezoelectric ceramic group C202 includes a longitudinal vibration piezoelectric ceramic group, a bending vibration piezoelectric ceramic group and five electrode sheets, wherein the longitudinal vibration piezoelectric ceramic group C202b is composed of two full-circle annular piezoelectric ceramics, the bending vibration ceramic group C202a is composed of 4 half-circle annular piezoelectric ceramics cut from two full-circle annular piezoelectric ceramics, each of which is made of lead zirconate titanate piezoelectric ceramics, has high output power, performs thickness direction polarization, and operates at d33A working mode; the two piezoelectric ceramics in the longitudinal vibration ceramic group C202b are oppositely polarized according to the polarization direction, each two half-ring ceramics in the bending vibration ceramic group C202a are oppositely polarized, the contact surface of each two adjacent half-ring piezoelectric ceramics belongs to the same polarization surface, and the polarization direction, the combination sequence and the working principle of the piezoelectric ceramic group are shown in fig. 7 and 9;
the longitudinal vibration piezoelectric ceramic group C202B drives the whole ultrasonic transducer C2 to generate second-order longitudinal vibration and is composed of two pieces of whole circular piezoelectric ceramic, three electrode plates C202C are used in total, the middle electrode plate C202C is connected with the positive electrode of a longitudinal vibration excitation power amplifier, and the electrode plates C202C on two sides are connected in series with the negative electrode plate of the bending vibration ceramic group C202a and connected with the common negative electrode of the two power amplifiers B;
the bending vibration piezoelectric ceramic group C202a drives the whole ultrasonic transducer C2 to generate four-order bending vibration and consists of four semicircular piezoelectric ceramics; 3 electrode plates C202C are provided, one of the electrode plates is shared with the longitudinal vibration ceramic group C202b, and the electrode plates comprise one electrode plate C202C connected with the anode of the bending excitation power amplifier and two electrode plates C202C connected with the common cathode of the two power amplifiers;
the end cover C203 is made of stainless steel materials, the consistency of the whole materials of the ultrasonic transducer C2 is kept, as shown in fig. 5 and fig. 6, a counter bore is formed in the end cover C203, the machining precision of each face of the counter bore is guaranteed during machining, a platform and a stagnation mounting hole are formed at the same time, the direction of the platform is consistent with that of the ultrasonic amplitude transformer C201, the end cover C203 is clamped when the ultrasonic transducer C2 is assembled, and the stagnation mounting hole of the end cover C203, a bending vibration piezoelectric ceramic group C202a cutting line, an ultrasonic amplitude transformer C201 stagnation mounting hole and an ultrasonic amplitude transformer C201 cutter containing groove are located on the same bus, so that longitudinal vibration and bending vibration are accurately generated, and the composite vibration is transmitted to a diamond cutter;
the piezoelectric detection element C204 is composed of two semicircular polyvinylidene fluoride piezoelectric materials as shown in fig. 10, and has the characteristics of fast response, high sensitivity, wide pressure measurement range and the like, when the ultrasonic transducer C2 generates high-frequency vibration, the piezoelectric detection element C205 generates corresponding deformation, based on the positive piezoelectric effect, high-frequency dynamic currents are generated on two sides of the piezoelectric detection element, longitudinal bending composite vibration is generated due to the ultrasonic transducer C2, two semicircular piezoelectric detection elements generate two different dynamic currents due to different charge variation generated by the longitudinal bending deformation, the currents are detected by a controller current sampling detection circuit, the sum of two current variation quantities (Δ a + Δ B) is a current response generated by the longitudinal vibration, and the difference of the current variation quantities (Δ a- Δ B) is a current response generated by the bending vibration, and then are processed by a main control CPU unit, the frequency and the phase of two current responses are identified, the generated longitudinal vibration and bending vibration are decoupled, impedance matching is carried out by regulating and controlling a power control circuit according to the analysis of the current responses when a load exists and a no load exists, the output voltage of an ultrasonic power supply A is regulated to carry out feedback control, and the elliptical vibrator is ensured to generate stable elliptical track vibration.
Based on the two-stationed-point high-frequency elliptical vibration cutting device provided by the invention, after the diamond cutter C1 is installed, the vibration track of the cutter point is measured through a laser vibration meter, and is fitted into an ellipse, as shown in fig. 11, the phase difference of two paths of amplitudes is nearly consistent with the phase difference of an initial excitation signal of an ultrasonic power supply, the frequency reaches 40kHz, and the feasibility of the invention is fully proved.
In summary, compared with the prior art, the invention has the following advantages:
the invention provides an elliptical vibrator supported by double stagnation point nodes, which is supported by bolts, namely point contact, and has small influence on the vibration characteristic of the elliptical vibrator, thereby improving the rigidity of the whole elliptical vibrator and improving the stability of high-frequency elliptical vibration of the elliptical vibrator.
The elliptical vibrator works in the axial direction and the bending direction of the ultrasonic transducer, so that the formed ellipse is a normal surface ellipse, and the efficient intermittent removal of workpiece materials is more favorably realized in the actual processing process. The elliptical vibrator provided by the invention works in a composite vibration mode of second-order longitudinal vibration and fourth-order bending vibration, can realize mode degeneracy, has the working frequency of 40kHz, and greatly improves the material removal efficiency and the processing quality over the existing structure.
According to the fixing of the packaging shell, the ball head fastening bolt and two standing wave nodes of the ultrasonic transducer can be assembled through the two standing point mounting threaded holes of the packaging shell, so that the bolt can be effectively prevented from loosening in the cutting process, the matching of the ball head fastening bolt and the ultrasonic transducer can be improved, the modal vibration mode of the ultrasonic transducer cannot be damaged, and the stability of the ultrasonic transducer is improved.
In the invention, the diamond cutter is arranged at the output end of an ultrasonic amplitude transformer of an ultrasonic transducer, the diamond cutter is designed according to the structure of the output end of the ultrasonic amplitude transformer, and is arranged at the output end through a small screw in a pre-tightening manner in the practical application process, so that the diamond cutter can generate high-frequency elliptical vibration when an elliptical vibrator vibrates at high frequency, and the elliptical vibration cutting processing of a processing material is realized.
The ultrasonic amplitude transformer can be selected according to actual requirements, such as a conical rod, a stepped rod, a Betzer curve rod and the like.
The ultrasonic amplitude transformer and the end cover are made of stainless steel materials with excellent mechanical properties, and the density, hardness and other physical properties of the stainless steel materials are close to those of piezoelectric ceramics, so that the overall properties of the ultrasonic transducer are close to each other, the heat conduction is close to the same, the local concentration of heat generated during processing is avoided, and the design of the overall ultrasonic transducer is facilitated.
The piezoelectric ceramic group adopts the whole circular ring piezoelectric ceramic, the output power is high, and the ceramic is polarized along the thickness direction; the ultrasonic horn comprises a longitudinal vibration piezoelectric ceramic group, a bending vibration piezoelectric ceramic group, a vibration control device and an ultrasonic horn, wherein the longitudinal vibration piezoelectric ceramic group generates axial vibration along an ultrasonic transducer, the bending vibration piezoelectric ceramic group is half-cut into paired semicircular piezoelectric ceramics, and the semicircular piezoelectric ceramics are assembled and installed together after being turned over, so that half of each piece of ceramics assembled together expands and contracts under the action of an electric field, and the ultrasonic horn generates vibration along the bending direction; the longitudinal vibration ceramic group and the bending vibration ceramic group are assembled together without separation, so that the whole transducer has a more compact structure, and can generate longitudinal and bending composite vibration at the same time, so that the diamond cutter arranged at the output end of the ultrasonic amplitude transformer generates elliptic track vibration.
The piezoelectric detection element of the invention is composed of two semicircular polyvinylidene fluoride piezoelectric materials, has the characteristics of quick response, high sensitivity and wide pressure measuring range, when the ultrasonic transducer generates high-frequency vibration, the piezoelectric detection element generates corresponding deformation, based on the positive piezoelectric effect, high-frequency dynamic current can be generated at two sides of the piezoelectric detection element, because the ultrasonic transducer generates longitudinal bending composite vibration, the charge variation generated by the longitudinal bending deformation of the two semicircular piezoelectric detection elements is different, two different dynamic currents can be generated, the current is detected by a controller current sampling detection circuit and then processed by a main control CPU unit, the sum of the two current variations is current response generated by longitudinal vibration, the difference of the two current variations is current response generated by bending vibration, and based on the corresponding relation between the current response and the amplitude of an output end, impedance matching is carried out by regulating and controlling the power control circuit, and the output voltage of the ultrasonic power supply is regulated to carry out feedback control, so that the elliptical vibrator is ensured to generate stable elliptical track vibration.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (8)
1. A high-frequency elliptical vibration cutting system is characterized by comprising an ultrasonic power supply, a power amplifier and an elliptical vibrator which are sequentially connected;
the ultrasonic power supply is used for generating two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency; wherein the frequency of the high-frequency sinusoidal alternating current signal is consistent with the working frequency of the elliptical vibrator;
the power amplifier comprises a bending vibration power amplifier and a longitudinal vibration power amplifier, and is used for amplifying two paths of high-frequency sinusoidal alternating current signals in a gain mode and respectively outputting a bending vibration excitation electric signal and a longitudinal vibration excitation electric signal;
the elliptical vibrator is used for respectively converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal, and realizing high-frequency elliptical vibration under the composite vibration of the bending vibration signal and the longitudinal vibration signal;
the resonance frequency of a second-order longitudinal vibration mode in the longitudinal vibration signal is consistent with that of a fourth-order bending vibration mode in the bending vibration signal, and two superposed standing wave nodes are shared; two standing wave nodes are used as supporting points for mounting the elliptical vibrator;
the elliptical vibrator includes: the device comprises a diamond cutter, an ultrasonic transducer, a fastening bolt, a packaging shell and a DB9 interface;
the diamond cutter is arranged in a cutter containing groove at the output end of the ultrasonic transducer; the ultrasonic transducer is used for respectively converting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal, working in a second-order longitudinal vibration mode and a fourth-order bending vibration mode, realizing mode degeneracy of the two vibration modes, sharing two coincident standing wave nodes, and arranging a standing point mounting hole at the standing wave node;
the fastening bolt is used for supporting the threaded hole through the stagnation point, jacking the threaded hole to the stagnation point mounting hole and fastening the ultrasonic transducer in the packaging shell;
standing point supporting threaded holes are processed on two sides of the packaging shell and used for standing point supporting, and slotted holes are formed in the front and the rear of the packaging shell and used for the ultrasonic transducer and the DB9 interface to penetrate and be fixed; wherein, one side of the packaging shell close to the diamond cutter is a front part, and one side close to the DB9 interface is a rear part;
the DB9 interface is installed on a packaging shell and is used for being connected with the ultrasonic transducer through a lead, and the power amplifier is connected through the male connector of the power amplifier output line DB 9.
2. The high-frequency elliptical vibration cutting system as set forth in claim 1, further comprising a controller having an input terminal connected to the elliptical vibrator and an output terminal connected to the ultrasonic power supply; the method is used for determining the resonance working point of the elliptical vibrator by analyzing the real-time amplitude change and phase change of the current of the elliptical vibrator, performing impedance matching in the cutting process, changing the output voltage of the ultrasonic power supply according to the load change, and ensuring that the working frequency is stable and the amplitude is kept unchanged.
3. The high frequency elliptical vibration cutting system of claim 1 wherein the ultrasonic transducer comprises an ultrasonic horn, a piezo ceramic stack, an end cap and a piezo sensing element;
the ultrasonic amplitude transformer and the piezoelectric ceramic group are of hollow structures, the end cover is of a stepped structure, a thread is machined at one end with a small area, a stagnation point mounting hole is formed at one end with a large area, and the ultrasonic amplitude transformer and the piezoelectric ceramic group are fixed by nesting the end cover; the ultrasonic amplitude transformer is in a stepped amplitude transformer structure with a conical section transition, and the output end of the ultrasonic amplitude transformer is provided with a tool accommodating groove; a standing point mounting hole is formed in the conical part of the bracket; the piezoelectric detection element is positioned between the tool containing groove and the conical part of the ultrasonic amplitude transformer and comprises two semicircular piezoelectric materials; another standing point mounting hole is formed in the end cover;
the piezoelectric ceramic group comprises a longitudinal vibration piezoelectric ceramic group, a bending vibration piezoelectric ceramic group and an electrode plate; the longitudinal vibration piezoelectric ceramic group comprises n pieces of whole circular ring piezoelectric ceramics, and electrode plates are arranged at two staggered sides between every two adjacent circular ring piezoelectric ceramics; the bending vibration piezoelectric ceramic group comprises m semicircular ring piezoelectric ceramics, each two semicircular ring piezoelectric ceramics form a whole circular ring piezoelectric ceramic, and electrode plates are arranged on two sides of each adjacent whole circular ring piezoelectric ceramics in a staggered mode; the two adjacent circular ring piezoelectric ceramics of the longitudinal vibration piezoelectric ceramic group are polarized in opposite directions; each semicircular ring piezoelectric ceramic in the bending vibration piezoelectric ceramic group is polarized with the adjacent semicircular ring piezoelectric ceramic in the opposite direction; the electrode plates on the same side as the electrode plates on the edge side of the piezoelectric ceramic group are connected with the common cathodes of the two power amplifiers; the electrode plate on the opposite side of the electrode plate on the edge side in the longitudinal vibration piezoelectric ceramic group is connected with the anode of a longitudinal vibration power amplifier; the electrode plate on the opposite side of the electrode plate on the edge side in the bending vibration piezoelectric ceramic group is connected with the anode of a bending vibration power amplifier;
the electrode plate is used for respectively transmitting the received bending vibration excitation electric signal and the longitudinal vibration excitation electric signal to the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the piezoelectric ceramic group is used for converting the bending vibration excitation electric signal and the longitudinal vibration excitation electric signal into a bending vibration signal and a longitudinal vibration signal, and the high-frequency elliptical vibration of the diamond cutter is realized under the composite vibration of the bending vibration signal and the longitudinal vibration signal;
the resonance frequency of the second-order longitudinal vibration mode is consistent with that of the fourth-order bending vibration mode, and two superposed standing wave nodes are shared; the stagnation point mounting hole on the end cover, the cutting line of the bending vibration piezoelectric ceramic group, the stagnation point mounting hole on the ultrasonic amplitude transformer and the tool containing groove on the ultrasonic amplitude transformer are positioned on the same bus.
4. The high-frequency elliptical vibration cutting system as set forth in claim 2, characterized in that the controller comprises a main control CPU unit, a current sampling detection circuit and a power control circuit;
the current sampling detection circuit is used for receiving a current signal transmitted by a voltage detection element in the elliptical vibrator;
the main control CPU unit is used for analyzing the current change and phase difference of two semicircular ring piezoelectric materials in the piezoelectric detection element, determining the resonance working point of the output end of the elliptical vibrator, and changing the amplitude of the high-frequency sinusoidal alternating current signal output by the ultrasonic power supply according to the load change;
the power control circuit is used for impedance matching in the cutting process under the control of the main control CPU unit, and stabilizing the resonant frequency in the cutting process.
5. A high-frequency elliptical vibration cutting system as claimed in claim 1 or 3, characterized in that the fastening bolt is a ball head fastening bolt, the hexagon socket is headless and the end is a ball head.
6. The high frequency elliptical vibration cutting system of claim 3 wherein the piezoelectric ceramic group is lead zirconate titanate piezoelectric ceramic.
7. The cutting method of a high-frequency elliptical vibration cutting system according to claim 1, characterized by comprising the steps of:
two paths of high-frequency sinusoidal alternating current signals with adjustable amplitude and frequency are gained by bending vibration excitation electric signals and longitudinal vibration excitation electric signals;
respectively converting the bending vibration excitation electrical signal and the longitudinal vibration excitation electrical signal into a bending vibration signal and a longitudinal vibration signal through the bending vibration piezoelectric ceramic group and the longitudinal vibration piezoelectric ceramic group;
the bending vibration signal and the longitudinal vibration signal jointly drive the elliptical vibrator to vibrate, so that high-frequency elliptical vibration is realized;
the second-order longitudinal vibration mode generated by the elliptical vibrator driven by the longitudinal vibration signal and the fourth-order bending vibration mode generated by the elliptical vibrator driven by the bending vibration signal have the same resonance frequency, and the two superposed standing wave nodes are used as supporting points for mounting the elliptical vibrator.
8. The cutting method of claim 7, further comprising the steps of:
detecting a current signal of the elliptical vibrator in the vibration process by using a piezoelectric detection element;
analyzing the change and the phase difference of the current signals, and determining the resonance working point of the elliptical vibrator;
continuously performing impedance matching in the cutting process, and stabilizing the resonant frequency in the cutting process;
and changing the amplitude of the high-frequency sinusoidal alternating current signal according to the load change.
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| CN114160398A (en) * | 2021-11-12 | 2022-03-11 | 华中科技大学 | Multi-mode resonant ultrasonic vibration fast cutter ultra-precise manufacturing system |
| CN114179156B (en) * | 2021-12-02 | 2023-04-28 | 大连理工大学 | Novel three-dimensional ultrasonic elliptical vibration cutting device |
| CN114474439A (en) * | 2022-02-17 | 2022-05-13 | 吉林大学 | Longitudinal-bending composite vibration two-dimensional ultrasonic machining device of inside diameter slicer |
| CN114700544B (en) * | 2022-02-23 | 2023-12-12 | 重庆大学 | Longitudinal torsion coupling three-dimensional ultrasonic knife handle device |
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