WO2019191848A1 - Procédés et appareils provoquant la vibration d'au moins un outil - Google Patents

Procédés et appareils provoquant la vibration d'au moins un outil Download PDF

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Publication number
WO2019191848A1
WO2019191848A1 PCT/CA2019/050416 CA2019050416W WO2019191848A1 WO 2019191848 A1 WO2019191848 A1 WO 2019191848A1 CA 2019050416 W CA2019050416 W CA 2019050416W WO 2019191848 A1 WO2019191848 A1 WO 2019191848A1
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WO
WIPO (PCT)
Prior art keywords
piezoelectric actuator
tool
vibration
piezoelectric
actuator
Prior art date
Application number
PCT/CA2019/050416
Other languages
English (en)
Inventor
Yusuf ALTINTAS
Jian Gao
Original Assignee
The University Of British Columbia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by The University Of British Columbia filed Critical The University Of British Columbia
Publication of WO2019191848A1 publication Critical patent/WO2019191848A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B31/00—Chucks; Expansion mandrels; Adaptations thereof for remote control
    • B23B31/02—Chucks
    • B23B31/10—Chucks characterised by the retaining or gripping devices or their immediate operating means
    • B23B31/12—Chucks with simultaneously-acting jaws, whether or not also individually adjustable
    • B23B31/20—Longitudinally-split sleeves, e.g. collet chucks
    • B23B31/201—Characterized by features relating primarily to remote control of the gripping means
    • B23B31/2012—Threaded cam actuator
    • 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
    • B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system
    • 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
    • B06B1/0607—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 using multiple elements
    • B06B1/0611—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 using multiple elements in a pile
    • B06B1/0618—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 using multiple elements in a pile of piezo- and non-piezoelectric elements, e.g. 'Tonpilz'
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B37/00—Boring by making use of ultrasonic energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C5/00—Milling-cutters
    • B23C5/26—Securing milling cutters to the driving spindle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
    • B24B1/04—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes subjecting the grinding or polishing tools, the abrading or polishing medium or work to vibration, e.g. grinding with ultrasonic frequency
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2260/00—Details of constructional elements
    • B23B2260/108—Piezoelectric elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B2270/00—Details of turning, boring or drilling machines, processes or tools not otherwise provided for
    • B23B2270/10—Use of ultrasound
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23C—MILLING
    • B23C2270/00—Details of milling machines, milling processes or milling tools not otherwise provided for
    • B23C2270/10—Use of ultrasound

Definitions

  • This disclosure relates generally to causing vibration of at least one tool.
  • Known tool holders may hold a tool (such as a drill bit or other cutting tool, for example) for rotation, and such a tool holder may also vibrate the tool.
  • a tool such as a drill bit or other cutting tool, for example
  • vibration of tools by known tool holders may not be appropriate for all applications of such tools.
  • a method of causing vibration of at least one tool comprising: causing vibration of the at least one tool in a first lateral direction in response to, at least, actuation of a first at least one piezoelectric actuator; and while causing the vibration of the at least one tool in the first lateral direction, causing vibration of the at least one tool in a second lateral direction different from the first lateral direction in response to, at least, actuation of a second at least one piezoelectric actuator.
  • a method of causing vibration of at least one tool comprising causing vibration of the at least one tool relative to a vibration actuator housing, wherein causing the vibration of the at least one tool relative to the vibration actuator housing comprises causing vibration, of a vibration actuator holding the at least one tool, relative to at least four support bodies spaced apart from each other and supporting the vibration actuator for vibration relative to the vibration actuator housing.
  • a method of causing vibration of at least one tool comprising causing vibration of the at least one tool in response to, at least, actuation of at least one piezoelectric actuator, wherein causing the vibration of the at least one tool comprises causing the vibration of the at least one tool in response to a measured impedance of the at least one piezoelectric actuator.
  • a method of causing vibration of at least one tool comprising causing vibration of the at least one tool in response to, at least, actuation of at least one piezoelectric actuator, wherein: causing the vibration of the at least one tool comprises modulating a voltage applied to a stator coil; modulating the voltage applied to the stator coil comprises inducing a voltage in a rotatable rotor coil; and at least a portion of the stator coil surrounds at least a portion of the rotor coil.
  • an apparatus for causing vibration of at least one tool comprising a vibration actuator operable to hold the at least one tool, the vibration actuator comprising: a first at least one piezoelectric actuator operable to, when the vibration actuator holds the at least one tool, vibrate the at least one tool in a first lateral direction; and a second at least one piezoelectric actuator operable to, when the vibration actuator holds the at least one tool, vibrate the at least one tool in a second lateral direction different from the first lateral direction while the first at least one piezoelectric actuator vibrates the at least one tool in the first lateral direction.
  • the apparatus further comprises at least one controller operable to, at least: cause the first at least one piezoelectric actuator to vibrate the at least one tool in the first lateral direction; and cause the second at least one piezoelectric actuator to vibrate the at least one tool in the second lateral direction.
  • an apparatus for causing vibration of at least one tool comprising: a vibration actuator operable to hold the at least one tool; a vibration actuator housing; and at least four support bodies spaced apart from each other and supporting the vibration actuator for vibration relative to the vibration actuator housing.
  • an apparatus for causing vibration of at least one tool comprising: a vibration actuator operable to hold the at least one tool, the vibration actuator comprising at least one piezoelectric actuator operable to, when the vibration actuator holds the at least one tool, vibrate the at least one tool; and at least one controller operable to, at least, cause the at least one piezoelectric actuator to vibrate the at least one tool in response to a measured impedance of the at least one piezoelectric actuator.
  • an apparatus for causing vibration of at least one tool comprising: a vibration actuator operable to hold the at least one tool, the vibration actuator comprising at least one piezoelectric actuator operable to, when the vibration actuator holds the at least one tool, vibrate the at least one tool; a rotatable rotor coil operable to transfer at least some of a voltage to the at least one piezoelectric actuator; a stator coil operable to induce the voltage in the rotor coil, wherein at least a portion of the stator coil surrounds at least a portion of the rotor coil; and at least one controller operable to, at least, apply a current to the stator coil.
  • FIG. 1 is a perspective view of a tool holding system according to one embodiment.
  • FIG. 2 is a cross-sectional view of a tool holder and a tool of the tool holding system of FIG. 1, taken along the line 2-2 in FIG. 1.
  • FIG. 3 is an exploded cross-sectional view of the tool holder and tool of FIG. 2.
  • FIG. 4 is an exploded perspective view of a piezoelectric actuator stack of the tool holder and tool of FIG. 2.
  • FIG. 5 is a top view of a piezoelectric actuator of the piezoelectric actuator stack of
  • FIG. 6 is a side view of the piezoelectric actuator of FIG. 5.
  • FIG. 7 is a top view of a piezoelectric actuator of the piezoelectric actuator stack of
  • FIG. 8 is a side view of the piezoelectric actuator of FIG. 7.
  • FIG. 9 is a schematic illustration of an equivalent circuit of a lumped parameter model of piezoelectric actuators of the piezoelectric actuator stack of FIG. 4.
  • FIG. 10 is a side view of the tool holder and tool of FIG. 2, illustrating a first longitudinal or axial mode of vibration of the tool holder and tool of FIG. 2.
  • FIG. 11 is a side view of the tool holder and tool of FIG. 2, illustrating a third bending mode of lateral or radial vibration of the tool holder and tool of FIG. 2.
  • FIG. 12 is a bottom view of the tool holder and tool of FIG. 2.
  • FIG. 13 is a cross-sectional view of the tool holder of FIG. 2, taken along the line 13- 13 in FIG. 12.
  • FIG. 14 is a bottom view of tool holder according to another embodiment.
  • FIG. 15 is a cross-sectional view of the tool holder of FIG. 14, taken along the line 15- 15 in FIG. 14.
  • FIG. 16 is a schematic illustration of a controller of the the tool holding system of
  • FIG. 17 is a schematic illustration of a lateral or radial vibration controller of the controller of FIG. 16.
  • FIG. 18 is a schematic illustration of a phase detector and other components of the lateral or radial vibration controller of FIG. 17.
  • FIG. 19 is a perspective view of a tool holding system according to another
  • FIG. 20 is a cross-sectional view of a tool holder and a tool of the tool holding system of FIG. 19, taken along the line 20-20 in FIG. 19.
  • FIG. 21 is an enlarged partial view of the cross-sectional view of FIG. 20.
  • FIG. 22 is a schematic illustration of an equivalent circuit of a lumped parameter model of piezoelectric actuators of a piezoelectric actuator stack of the tool holder of FIG. 20.
  • FIG. 23 is a schematic illustration of a controller of the tool holding system of FIG. 19.
  • FIG. 24 is a schematic illustration of a controller according to another embodiment.
  • a tool holding system is shown generally at 100 and includes a tool holder shown generally at 102.
  • the tool holder 102 includes a tool interface 104, a vibration actuator housing 106, and a vibration actuator 108.
  • the tool interface 104, the vibration actuator housing 106, and other components described herein may be manufactured from tool steel or stainless steel (such as stainless steel 304), for example.
  • the tool interface 104 may be configured to mount the tool holder 102 to a spindle or to another part of a machine tool, and may be a CAT tool interface (such as a CAT40 tool interface, which may be conical), an HSK tool interface (such as an HSK63 tool interface, which may be a hollow shank), or another interface mountable to a machine tool (which may be part of a computer numerical control (CNC) system) for milling, drilling, machining, or other operations, for example.
  • CAT tool interface such as a CAT40 tool interface, which may be conical
  • HSK tool interface such as an HSK63 tool interface, which may be a hollow shank
  • CNC computer numerical control
  • the tool interface 104 is mountable to a machine tool that may rotate the tool holder 102 about an axis of rotation 110, so the tool interface 104 is configured to mount the tool holder 102 for rotation generally about the axis of rotation 110, although alternative embodiments may differ.
  • “generally about the axis of rotation 110” refers to rotation that may not be precisely about the axis of rotation 110, but that may function the same as or substantially the same as rotation about the axis of rotation 110. More generally,“generally” herein includes variations to an applicable aspect, embodiment, or component described herein that may function the same as or substantially the same as such applicable aspect, embodiment, or component (as the case may be) described herein.
  • FIGS. 2 and 3 illustrate X, Y, and Z axes of a Cartesian coordinate system for ease of reference.
  • the axis of rotation 110 extends generally along the Z axis. Therefore, a direction generally along the Z axis may be referred to as an axial direction, and directions that are generally orthogonal to the Z axis (such as directions generally along the X and Y axes, for example) may be referred to as radial directions.
  • the direction generally along the Z axis may also be referred to as a longitudinal direction, and other directions (such as directions generally along the X and Y axes, for example) may be referred to as lateral directions.
  • X, Y, and Z axes are simply examples for ease of reference to one embodiment, and alternative embodiments need not be characterized by such axes, or alternative embodiments may be characterized by different axes that may differ from axes of a Cartesian coordinate system.
  • the tool interface 104 defines threads 112 shown in FIGS. 2 and 3.
  • the vibration actuator housing 106 defines threads 114 complementary to the threads 112 to permit coupling the tool interface 104 to the vibration actuator housing 106 so that the tool interface 104 and the vibration actuator housing 106 may together be mountable to a machine tool for rotation generally about the axis of rotation 110.
  • the vibration actuator housing 106 includes electrically conductive slip rings 116, 118, 120, and 122 spaced apart from each other along the axis of rotation 110 (or otherwise electrically insulated from each other) and generally rotationally symmetric about this axis of rotation 110. Therefore, the slip rings 116, 118, 120, and 122 are positioned on an external surface of the vibration actuator housing 106 for generally constant electrically conductive contact with respective electrodes (or brashes) 124, 126, 128, and 130 throughout rotation of the tool holder 102 around the axis of rotation 110.
  • the vibration actuator housing 106 has a generally annular mounting surface 132 opposite the threads 114, and defines a generally cylindrical cavity 134 open at an opening in the mounting surface 132. Also, as shown in FIGS. 1, 2, and 3, the vibration actuator housing 106 defines generally radial mass balance holes, shown generally at 136 and 138 for example, which may be used to balance the tool holder 102 by adjusting a center of mass of the tool holder 102 to be close to the axis of rotation 110, for example.
  • the vibration actuator 108 includes a generally annular mounting flange 140, which may be manufactured from tool steel or stainless steel (such as stainless steel 304), and which may be mountable against the mounting surface 132 as shown in FIGS. 2 and 3.
  • the mounting flange 140 may define through-holes to receive respective fasteners (such as screws or bolts), shown at 142 and 144 for example, and such fasteners may be received in respective threaded openings of the mounting surface 132 in the vibration actuator housing 106 to mount the mounting flange 140 against the mounting surface 132 and to the vibration actuator housing 106.
  • the vibration actuator 108 may also be mountable to a machine tool together with the tool interface 104 and the vibration actuator housing 106 for rotation generally about the axis of rotation 110.
  • the vibration actuator 108 also includes a piezoelectric actuator stack shown generally at 146 and including a first piezoelectric actuator 148, a second piezoelectric actuator 150, a third piezoelectric actuator 152, a fourth piezoelectric actuator 154, a fifth piezoelectric actuator 156, and a sixth piezoelectric actuator 158.
  • a piezoelectric actuator stack shown generally at 146 and including a first piezoelectric actuator 148, a second piezoelectric actuator 150, a third piezoelectric actuator 152, a fourth piezoelectric actuator 154, a fifth piezoelectric actuator 156, and a sixth piezoelectric actuator 158.
  • the piezoelectric actuator 148 has a top side (or, more generally, a first side) shown generally at 160 and bottom side (or, more generally, a second side) shown generally at 162 opposite the top side 160.
  • the piezoelectric actuator 148 may be generally annular, and may have an external diameter of about 40 millimeters (mm), or more generally an external diameter between about 30 mm and about 45 mm.
  • the material of the piezoelectric actuator 148 may be a hard piezoelectric material such as PZT-8. Extending between the top side 160 and the bottom side 162, the piezoelectric actuator 148 defines a generally circular and generally central through-opening 164, which may have an internal diameter of about 15 mm.
  • the piezoelectric actuator 148 includes a first arcuate or semi-annular piezoelectric body 166 extending around a first portion of the through- opening 164, and a second arcuate or semi- annular piezoelectric body 168 extending around a second portion of the through-opening 164.
  • the piezoelectric bodies 166 and 168 are coupled together at respective arc ends by electrically insulating bodies (which may be insulating bands) 170 and 172 extending generally along a diameter 174 of the piezoelectric actuator 148 on diametrically opposite sides of the through-opening 164.
  • the piezoelectric bodies 166 and 168 have opposite polarities in a direction between the top side 160 and the bottom side 162.
  • an electric field having a first polarity applied between the top side 160 and the bottom side 162 may cause the piezoelectric body 166 to contract in a direction generally along the axis of rotation 110, and may cause the piezoelectric body 168 to expand in the direction generally along the axis of rotation 110.
  • an electric field having a second polarity opposite the first polarity and applied between the top side 160 and the bottom side 162 may cause the piezoelectric body 166 to expand in the direction generally along the axis of rotation 110, and may cause the
  • the piezoelectric actuator 150 is substantially the same as the piezoelectric actuator 148 and includes a third piezoelectric body 176 that is substantially the same as the piezoelectric body 166, and a fourth piezoelectric body 178 that is substantially the same as the piezoelectric body 168.
  • the piezoelectric actuator 152 is also substantially the same as the piezoelectric actuator 148 and includes a fifth piezoelectric body 182 that is substantially the same as the piezoelectric body 166, and a sixth piezoelectric body 184 that is substantially the same as the piezoelectric body 168.
  • the piezoelectric actuator 154 is also substantially the same as the piezoelectric actuator 148 and includes a seventh piezoelectric body 186 that is substantially the same as the piezoelectric body 166, and an eighth piezoelectric body 188 that is substantially the same as the piezoelectric body 168.
  • the piezoelectric actuator 156 has a top side shown generally at 190 and a bottom side shown generally at 192 and opposite the top side 190, and includes a generally annular (or a ninth) piezoelectric body 194 defining a through-opening 196 extending between the top side 190 and the bottom side 192.
  • the piezoelectric actuator 158 is substantially the same as the piezoelectric actuator 156 and includes a tenth
  • piezoelectric body 197 although the piezoelectric bodies 194 and 197 have opposite polarities in a direction between the top side 190 and the bottom side 192.
  • an electric field having a first polarity applied between the top side 190 and the bottom side 192 may cause the piezoelectric body 194 to contract in the direction generally along the axis of rotation 110, and an electric field having a second polarity opposite the first polarity and applied between top and bottom sides of the piezoelectric body 197 may cause the
  • the piezoelectric body 194 to contract in the direction generally along the axis of rotation 110. Further, the electric field having the second polarity applied between the top side 190 and the bottom side 192 may cause the piezoelectric body 194 to expand in the direction generally along the axis of rotation 110, and the electric field having the first polarity applied between the top and bottom sides of the piezoelectric body 197 may cause the piezoelectric body 194 to expand in the direction generally along the axis of rotation 110.
  • the piezoelectric actuator stack 146 also includes electrodes 198, 200, 202, 204, 206, 208, and 210.
  • the electrode 198 includes a generally annular electrically conductive body 212 defining a through-opening 214.
  • the electrode 198 also includes a generally radially extending electrical contact 216 in electrically conductive contact with the electrical conductor 212.
  • the electrodes 200, 202, 204, 206, 208, and 210 are substantially the same as the electrode 198.
  • the piezoelectric actuator stack 146 may be assembled by aligning the through- openings as described above of the piezoelectric actuators 148, 150, 152, 154,
  • the top side 160 of the piezoelectric actuator 148 may be positioned against the electrically conductive body 212 of the electrode 184 such that the electrically conductive body 212 of the electrode 184 is in electrically conductive contact with both piezoelectric bodies 166 and 168 of the piezoelectric actuator 148;
  • the bottom side 162 of the piezoelectric actuator 148 and the top side of the piezoelectric actuator 150 may be positioned against the electrically conductive body of the electrode 200 such that the electrically conductive body of the electrode 200 is in electrically conductive contact with both piezoelectric bodies 166 and 168 of the piezoelectric actuator 148 and with both piezoelectric bodies 176 and 178 of the piezoelectric actuator 150;
  • actuator 152 may be positioned against the electrically conductive body of the electrode 202 such that the electrically conductive body of the electrode 202 is in electrically conductive contact with both piezoelectric bodies 176 and 178 of the piezoelectric actuator 150 and with both piezoelectric bodies 182 and 184 of the piezoelectric actuator 152;
  • actuator 154 may be positioned against the electrically conductive body of the electrode 204 such that the electrically conductive body of the electrode 204 is in electrically conductive contact with both piezoelectric bodies 182 and 184 of the piezoelectric actuator 152 and with both piezoelectric bodies 186 and 188 of the piezoelectric actuator 154;
  • the bottom side of the piezoelectric actuator 154 and the top side 190 of the piezoelectric actuator 156 may be positioned against the electrically conductive body of the electrode 206 such that the electrically conductive body of the electrode 206 is in electrically conductive contact with both piezoelectric bodies 186 and 188 of the piezoelectric actuator 154 and with the piezoelectric body 194 of the piezoelectric actuator 156;
  • the bottom side 192 of the piezoelectric actuator 156 and the top side of the piezoelectric actuator 158 may be positioned against the electrically conductive body of the electrode 208 such that the electrically conductive body of the electrode 208 is in electrically conductive contact with the piezoelectric body 194 of the piezoelectric actuator 156 and with the piezoelectric body of the piezoelectric actuator 158;
  • the bottom side of the piezoelectric actuator 158 may be positioned against the electrically conductive body of the electrode 210 such that the electrically conductive body of the electrode 210 is in electrically conductive contact with the piezoelectric body of the piezoelectric actuator 158.
  • the piezoelectric actuators 148, 150, 152, 154, 156, and 158 may be aligned in a longitudinal direction generally along the axis of rotation 110.
  • the electrically insulating bodies 170 and 172 of the piezoelectric actuator 148 may be positioned generally along the same lateral or radial direction (a direction along the Y axis in the embodiment of FIG. 4) as the electrically insulating bodies 176 and 178 of the piezoelectric actuator 150, although the piezoelectric actuator 150 may be rotated relative to the piezoelectric actuator 148 so that
  • the piezoelectric body 166 is aligned in the longitudinal direction generally along the axis of rotation 110 with the piezoelectric body 178 (which has a polarity opposite of the polarity of the piezoelectric body 166), and so that
  • the piezoelectric body 168 is aligned in the longitudinal direction generally along the axis of rotation 110 with the piezoelectric body 176 (which has a polarity opposite of the polarity of the piezoelectric body 168;
  • the piezoelectric actuators 152 and 154 may be aligned so that the electrically insulating bodies of the piezoelectric actuators 152 and 154 are aligned along a lateral or radial direction (a direction along the X axis in the embodiment of FIG. 4) orthogonal to (or, more generally, different from) the lateral or radial direction of the electrically conductive body of the piezoelectric actuators 148 and 150, although the piezoelectric actuator 154 may be rotated relative to the piezoelectric actuator 152 so that
  • the piezoelectric body 182 is aligned in the longitudinal direction generally along the axis of rotation 110 with the piezoelectric body 188 (which has a polarity opposite of the polarity of the piezoelectric body 182), and so that
  • the piezoelectric body 184 is aligned in the longitudinal direction generally along the axis of rotation 110 with the piezoelectric body 186 (which has a polarity opposite of the polarity of the piezoelectric body 184).
  • a generally cylindrical fastener (or rod) 220 may be received through the through-openings of the piezoelectric actuators 148, 150, 152, 154, 156, and 158 and through the through-openings of the electrodes 198, 200, 202, 204, 206, 208, and 210 along the central axis 218 (shown in FIG. 4) of the piezoelectric actuator stack 146.
  • the fastener 220 may also extend through a back mass body 222, and the fastener 220 may hold the back mass body 222 against the electrode 210 of the piezoelectric actuator stack 146, for example by threading a nut 224 on a threaded end (which may have fine threads) of the fastener 220.
  • the fastener 220 may also hold a front mass (or ending mass) body 226 against the electrode 198 of the piezoelectric actuator stack 146 (and thus against an end of the piezoelectric actuator stack 148 opposite the back mass body 222), for example by threadedly coupling the fastener 220 to the front mass body 226.
  • the fastener 220, the back mass body 222, nut 224, and the front mass body 226 may also be manufactured from tool steel or stainless steel (such as stainless steel 304), for example.
  • the nut 224 may preload the piezoelectric actuator stack 146, which may protect the piezoelectric actuator stack 146 from tensile loads, and a torque of about 100 Newton-meters (Nm) to about 150 Nm on the nut 224 may be appropriate.
  • a tool such as a drill bit or other cutting tool, for example, which may be a carbide tool
  • a tool 228 may be mounted to the vibration actuator 108, for example using a bit chuck or collet nut 230 (which may threadedly engage external threads on the vibration actuator 108) to hold (or clamp) the tool 228 in a frustoconical opening shown generally at 232 in the front mass body 226.
  • the tool 228 may thus be positioned and moved (for example, by rotation generally about the axis of rotation 110, by vibration by the vibration actuator 108, or by both) for drilling, milling, machining, or other operations for example.
  • the tool 228 may be generally elongate in a longitudinal direction generally along the axis of rotation 110, and the back mass body 222 and the tool 228 may be aligned in the longitudinal direction generally along the axis of rotation 110.
  • the electrodes 198, 202, 206, and 210 may be electrically conductively connected to a common reference voltage, such as a ground voltage for example.
  • the electrodes 198, 202, 206, and 210 may be electrically conductively connected to the slip ring 116, which may be electrically conductively connected to the slip ring 116, which may be electrically conductively connected to the electrode 124, which may be at such a reference voltage.
  • the electrode 200 may be electrically conductively connected to the slip ring 118, which may be electrically conductively connected to the electrode 126;
  • the electrode 204 may be electrically conductively connected to the slip ring 120, which may be electrically conductively connected to the electrode 128;
  • the electrode 208 may be electrically conductively connected to the slip ring 122, which may be electrically conductively connected to the electrode 130.
  • a first voltage applied to the electrode 126 may be transmitted to the electrode 200, which may apply an electric field having a first polarity to the piezoelectric actuator 148, and which may apply an electric field having a second polarity opposite the first polarity to the piezoelectric actuator 150, which may cause the piezoelectric bodies 166 and 178 to contract in a longitudinal or axial direction (a direction along the Z axis in the embodiment of FIG.
  • the piezoelectric bodies 168 and 176 may expand in the longitudinal or axial direction, thereby bending or deflecting the piezoelectric actuator stack 146 in a direction that causes the front mass body 226 (and the tool 228) to be deflected relative to the back mass body 222 in a first lateral or radial direction (a direction along the X axis in the embodiment of FIG. 4).
  • a second voltage opposite the first voltage and applied to the electrode 126 may be transmitted to the electrode 200, which may apply an electric field having the first polarity to the piezoelectric actuator 150, and which may apply an electric field having the second polarity to the piezoelectric actuator 148, which may cause the piezoelectric bodies 166 and 178 to expand in the longitudinal or axial direction and may cause the piezoelectric bodies 168 and 176 to contract in the longitudinal or axial direction, thereby bending or deflecting the piezoelectric actuator stack 146 in a direction that causes the front mass body 226 (and the tool 228) to be deflected relative to the back mass body 222 in the first lateral or radial direction (a direction along the X axis in the embodiment of FIG. 4) but opposite the deflection caused by applying the first voltage applied to the electrode 126.
  • applying an alternating voltage (or, more generally, a varying voltage) to the electrode 126 may cause vibration (or, more generally, movement) of the front mass body 226 (and the tool 228) in a first lateral or radial direction (the X axis in the embodiment of FIG. 4), and the piezoelectric actuators 148 and 150 may individually or collectively function as a first lateral or radial piezoelectric actuator (for example, an X-axis piezoelectric actuator), and the voltage applied to the electrode 126 may be referred to as a first lateral or radial actuation voltage (for example, V x ). Further, the slip ring 118, the electrode 126, and the voltage applied to the electrode 126 may be associated with the first lateral or radial direction (the X axis in the embodiment of FIG. 4).
  • a first voltage applied to the electrode 128 may be transmitted to the electrode 204, which may apply an electric field having a first polarity to the piezoelectric actuator 152, and which may apply an electric field having a second polarity opposite the first polarity to the piezoelectric actuator 154, which may cause the piezoelectric bodies 182 and 188 to contract in the longitudinal or axial direction and may cause the piezoelectric bodies 184 and 186 to expand in the longitudinal or axial direction, thereby bending or deflecting the piezoelectric actuator stack 146 in a direction that causes the front mass body 226 (and the tool 228) to be deflected relative to the back mass body 222 in a second lateral or radial direction (a direction along the Y axis in the embodiment of FIG. 4) orthogonal to (or, more generally, different from) the first lateral or radial direction.
  • a second voltage opposite the first voltage and applied to the electrode 128 may be transmitted to the electrode 204, which may apply an electric field having the first polarity to the piezoelectric actuator 152, and which may apply an electric field having the second polarity to the piezoelectric actuator 154, which may cause the piezoelectric bodies 182 and 188 to expand in the longitudinal or axial direction and may cause the piezoelectric bodies 184 and 186 to contract in the longitudinal or axial direction, thereby bending or deflecting the piezoelectric actuator stack 146 in a direction that causes the front mass body 226 (and the tool 228) to be deflected relative to the back mass body 222 in the second lateral or radial direction (a direction along the Y axis in the embodiment of FIG. 4) but opposite the deflection caused by applying the first voltage applied to the electrode 128.
  • applying an alternating voltage (or, more generally, a varying voltage) to the electrode 128 may cause vibration (or, more generally, movement) of the front mass body 226 (and the tool 228) in a second lateral or radial direction (the Y axis in the embodiment of FIG. 4) orthogonal to (or, more generally, different from) the first lateral or radial direction, and the piezoelectric actuators 152 and 154 may individually or collectively function as a second lateral or radial piezoelectric actuator (for example, an Y-axis piezoelectric actuator), and the voltage applied to the electrode 128 may be referred to as a second lateral or radial actuation voltage (for example, V Y ).
  • the slip ring 120, the electrode 128, and the voltage applied to the electrode 128 may be associated with the second lateral or radial direction (the Y axis in the embodiment of FIG. 4).
  • a first voltage applied to the electrode 130 may be transmitted to the electrode 208, which may apply an electric field having a first polarity to the piezoelectric actuator 156, and which may apply an electric field having a second polarity opposite the first polarity to the piezoelectric actuator 158, which may cause the piezoelectric body 190 and the piezoelectric body 197 to contract in the longitudinal or axial direction, thereby causing the front mass body 226 (and the tool 228) to move relative to the back mass body 222 in a longitudinal or axial direction (a direction along the Z axis in the embodiment of FIG. 4) orthogonal to (or, more generally, different from) the first and second lateral or radial directions.
  • a second voltage opposite the first voltage and applied to the electrode 130 may be transmitted to the electrode 208, which may apply an electric field having the first polarity to the piezoelectric actuator 158, and which may apply an electric field having the second polarity to the piezoelectric actuator 156, which may cause the piezoelectric body 190 and the piezoelectric body 197 to expand in the longitudinal or axial direction, thereby causing the front mass body 226 (and the tool 228) to move relative to the back mass body 222 in the longitudinal or axial direction (a direction along the Z axis in the embodiment of FIG. 4) but opposite the movement caused by applying the first voltage applied to the electrode 130.
  • applying an alternating voltage (or, more generally, a varying voltage) to the electrode 130 may cause vibration (or, more generally, movement) of the front mass body 226 (and the tool 228) in a longitudinal or axial direction (the Z axis in the embodiment of FIG. 4) orthogonal to (or, more generally, different from) the first and second lateral or radial directions, and the piezoelectric actuators 156 and 158 may individually or collectively function as a longitudinal or axial piezoelectric actuator (for example, a Z-axis piezoelectric actuator), and the voltage applied to the electrode 130 may be referred to as a longitudinal or axial actuation voltage (for example, V z ).
  • the slip ring 122, the electrode 130, and the voltage applied to the electrode 130 may be associated with the longitudinal or axial direction (the Z axis in the embodiment of FIG. 4).
  • the piezoelectric actuator stack 146 may function as a vibration actuator of the front mass body 226 (and the tool 228) in three degrees of freedom, namely in directions in a first lateral or radial direction (the X axis), in a second lateral or radial direction (the Y axis), and in a longitudinal or axial direction (the Z axis) in the embodiment shown, although alternative embodiments may differ. Also, in the embodiment shown, the piezoelectric actuator stack 146 may be positioned in the cavity 134 the vibration actuator housing 106, so the piezoelectric actuator stack 146 may be referred to as an embedded vibration actuator.
  • vibration as described herein may have a frequency of about 15 kilohertz (kHz) or higher, of about 16 kHz or higher, or between about 15 kHz and about 20 kHz, and more generally may be ultrasonic. Further, in some embodiments, vibration as described herein may have an amplitude of about 20 micrometers (pm) to about 25 pm, an amplitude of about 20 micrometers (pm) to about 30 pm, or an amplitude less than about 30 pm, for example.
  • kHz kilohertz
  • An equivalent circuit shown in FIG. 9 of a lumped parameter model may facilitate identification of sizes, shapes, or materials of the piezoelectric actuators 148 and 150.
  • V in is a voltage applied to the electrode 126 relative to the reference voltage of the electrode 124
  • C 0 is the capacitance (which may be measured by a multimeter, for example) of the piezoelectric bodies 166, 168, 176, and 178 of the
  • y is a force factor of the piezoelectric actuators 148 and 150
  • Y 33 is Young’s modulus of the piezoelectric bodies 166, 168, 176, and 178 of the piezoelectric actuators 148 and 150
  • d 33 is the piezoelectric strain along the thickness (and polarization direction) of the piezoelectric bodies 166, 168, 176, and 178 of the piezoelectric actuators 148 and 150
  • A is a cross-sectional area of the piezoelectric actuators 148 and 150
  • T is the thickness (shown in FIG. 6, for
  • C m is an equivalent capacitance related to stiffness k of the piezoelectric actuators 148 and 150
  • R m is an equivalent
  • c is a damping coefficient of the piezoelectric actuators 148 and 150.
  • a resonant frequency f r of the piezoelectric actuators 148 and 150 may be modeled as 1
  • the capacitance C 0 of the piezoelectric bodies 166, 168, 176, and 178 of the piezoelectric actuators 148 and 150 may result from their material properties as
  • the cross-sectional A and the thickness t of the piezoelectric actuators 148 and 150 may be chosen to cause the piezoelectric actuators 148 and 150 to have a capacitance C 0 according to Equation 2 that corresponds to a desired capacitance C 0 according to Equation 1 to achieve a desired resonant frequency f r and a desired anti-resonant frequency f a .
  • FIG. 9 has been described with reference to the piezoelectric actuators 148 and 150, a similar equivalent circuit of a similar lumped parameter model may facilitate identification of sizes, shapes, or materials of the piezoelectric actuators 152 and 154, or of the piezoelectric actuators 156 and 158.
  • actuation of the front mass body 226 (and the tool 228) in the longitudinal or axial direction may cause displacement w(z, t) of the vibration actuator 108 and the tool 228 at a location z in the longitudinal or axial direction (on the Z axis in the embodiment of FIG. 10) and at a time t according to a beam equation
  • E Young’s modulus of the vibration actuator 108 and the tool 2208
  • A(z) is a cross sectional area of the vibration actuator 108 and the tool 228 at a location z in the longitudinal or axial direction (on the Z axis in the embodiment of FIG. 10)
  • p is a mass density of the vibration actuator 108 and the tool 228.
  • FIG. 10 illustrates a neutral node 234 of longitudinal or axial displacement of the vibration actuator 108 and the tool 228 in a first longitudinal or axial mode of vibration, which has a mode shape 235 in the embodiment shown.
  • the piezoelectric actuators 156 and 158 (which may collectively function as a longitudinal or axial piezoelectric actuator) may be positioned near the neutral node 234.
  • actuation of the front mass body 226 (and the tool 228) in a lateral or radial direction may cause displacement u(z, t) of the vibration actuator 108 and the tool 228 according to Euler’s beam model as (Eq. 4) where / is a moment of inertia of the vibration actuator 108 and the tool 228.
  • Natural frequencies of the vibration actuator 108 and the tool 228 from actuation of the front mass body 226 (and the tool 228) in the lateral or radial direction (along the X axis in the embodiment of FIG. 10) may be identified (for example, using finite-element analysis in software such as COMSOL MultiphysicsTM) from Equation 4 with free-free boundary conditions lateral or radial
  • FIG. 11 illustrates neutral nodes 236, 238, 240, and 242 of lateral or radial bending of the vibration actuator 108 and the tool 228 in a third bending mode of lateral or radial vibration, which has a mode shape 243 in the embodiment shown.
  • the piezoelectric actuators 148, 150, 152 and 154 may be positioned between the neutral nodes 240 and 242, or more generally around a peak shape of the lateral or radial mode shape 243.
  • FIG. 11 illustrates actuation of the front mass body 226 (and the tool 228) in a direction along the X axis
  • neutral nodes of lateral or radial bending may be identified for actuation in other directions, such as actuation in a direction along the Y axis shown in FIG.
  • a desired resonant frequency f r in a longitudinal or axial direction (for example, in a direction along the Z axes as described above) may be about 16.5 kHz.
  • the thickness T of the piezoelectric actuators 148, 150 is also desirable. Also, in some embodiments, the thickness T of the piezoelectric actuators 148, 150,
  • the thickness T of the piezoelectric actuators 155 and 158 may be about 4.5 mm.
  • support bodies 244, 246, 248, and 250 hold the vibration actuator 108 for vibration relative to the mounting flange 140 (and thus relative to the vibration actuator housing 106 when the mounting flange 140 is mounted to the vibration actuator housing 106).
  • the support bodies 244, 246, 248, and 250 extend generally radially between the mounting flange 144 and the front mass body 226, and are resiliently deformable bodies such as leaf springs, for example.
  • the support bodies 244, 246, 248, and 250 may be positioned longitudinally or axially at longitudinal or axial positions of the neutral nodes 234 and 240 shown in FIGS. 10 and 11.
  • the support bodies 244, 246, 248, and 250 may also be positioned peripherally around the axis of rotation 110 with the support bodies 246 and 250 diametrically opposed from each other about the axis of rotation 110 in one lateral direction (a direction along the X axis in the embodiment of FIG. 13), and with the support bodies 244 and 248 diametrically opposed from each other about the axis of rotation 110 in a different lateral direction (a direction along the Y axis in the embodiment of FIG. 13). Therefore, referring to FIGS.
  • the support bodies 244, 246, 248, and 250 may be positioned peripherally around the axis of rotation 110 such that vibration induced by actuation of the piezoelectric actuators 148 and 150 is in a direction generally involving rotation about the support bodies 244 and 248, and vibration caused by actuation of the piezoelectric actuators 152 and 154 is in a direction that involves rotation around the support bodies 246 and 250.
  • a tool holder according to another embodiment is shown generally at 252 and includes a vibration actuator housing 254 and a vibration actuator 256.
  • the vibration actuator housing 254 may be similar to the vibration actuator housing 106 as described above.
  • the vibration actuator 256 may be similar to the vibration actuator 108 as described above, and includes a mounting flange 258 that may be similar to the mounting flange 140, and a front mass body 260 that may be similar to the front mass body 226.
  • support bodies 262, 264, 266, and 268 may hold the vibration actuator 256 for vibration relative to the vibration actuator housing 254.
  • the support bodies 262, 264, 266, and 268 may be positioned longitudinally and peripherally similarly to the support bodies 244,
  • the support bodies 262, 264, 266, and 268 may also be generally radially extending resilient bodies such as leaf springs, for example.
  • the support bodies 262, 264, 266, and 268 may have a longitudinally extending step shape, as shown in the support bodies 262 and 266 in FIG. 15.
  • Support bodies such as those described herein may have different stiffnesses, which may depend on widths, lengths, thicknesses, or other characteristics of the support bodies.
  • support bodies opposed from each in one lateral direction such as the support bodies 244 and 248 or the support bodies 262 and 266 that are opposed from each in a direction along a Y axis
  • may be stiffer than support bodies opposed from each in another lateral direction such as the support bodies 246 and 250 or the support bodies 264 and 268 that are opposed from each in a direction along an X axis).
  • support bodies such as those described herein may isolate vibrations (for example by reducing attenuation of such vibrations) of a vibration actuator (such as the vibration actuator 108 or 256) from a vibration actuator housing (such as the vibration actuator housing 106 or 254) supporting the vibration actuator, and from other components of a machine tool.
  • a vibration actuator such as the vibration actuator 108 or 256
  • a vibration actuator housing such as the vibration actuator housing 106 or 254 supporting the vibration actuator
  • the tool holding system 100 further includes a controller 270 that may be operable to control one or more of:
  • V Y V 0 sin(2 nf x t + q g ),
  • V z V 0 sin(2? f z t)
  • V 0 is a voltage amplitude
  • f x is a lateral or radial vibration frequency
  • f z is a longitudinal or axial vibration frequency
  • q g is a lateral or radial phase difference between vibrations in the two lateral or radial directions.
  • Applying the voltage V x to the electrode 126 may cause a current I x to flow through the piezoelectric actuators 148 and 150
  • applying the voltage V Y to the electrode 128 may cause a current I Y to flow through the piezoelectric actuators 152 and 154
  • applying the voltage V z to the electrode 130 may cause a current I z to flow through the piezoelectric actuators 156 and 158.
  • capacitance, inductance, or both (more generally, reactance) of the piezoelectric actuators may cause phase differences such that
  • I x I ox s ⁇ n ⁇ 2nf x t + f c ),
  • I Y I 0Y sin(2 nf x t + q g + f g ), and
  • I z I oz sm(2nf z t + f z )
  • I ox is an amplitude of current flow through the lateral or radial X-axis piezoelectric actuator including the piezoelectric actuators 148 and 150
  • 1 0Y is an amplitude of current flow through the lateral or radial Y-axis piezoelectric actuator including the piezoelectric actuators 152 and 154
  • I oz is an amplitude of current flow through the longitudinal or axial Z-axis piezoelectric actuator including the piezoelectric actuators 156 and 158
  • f c , f g , and f z are phase differences between I x and V x , I Y and V Y , I z and V z , respectively.
  • the controller 270 may include a first lateral or radial vibration controller 272 for controlling vibration of the vibration actuator 108 in a first lateral or radial direction (such as a direction along the X axis in the embodiment described above), a second lateral or radial vibration controller 274 for controlling vibration of the vibration actuator 108 in a second lateral or radial direction (such as a direction along the Y axis in the embodiment described above), and a longitudinal or axial vibration controller 276 for controlling vibration of the vibration actuator 108 in a longitudinal or axial direction (such as a direction along the Z axis in the embodiment described above).
  • a first lateral or radial vibration controller 272 for controlling vibration of the vibration actuator 108 in a first lateral or radial direction (such as a direction along the X axis in the embodiment described above)
  • a second lateral or radial vibration controller 274 for controlling vibration of the vibration actuator 108 in a second lateral or radial direction (such as a direction along the
  • the controller 270 may receive or store one or more inputs 278 identifying a lateral or radial resonant frequency f rX0 of the vibration actuator 108 and the tool 228 without a load, and one or more inputs 280 identifying a longitudinal or axial resonant frequency f rZ0 of the vibration actuator 108 and the tool 228 without a load.
  • the resonant frequencies f rX0 and f rZ0 may be identified for a particular actuator and tool or varied, and identifications of the resonant frequencies f rX0 and f rZ0 may be stored in one or more data stores of the controller 270, encoded in one or more input signals provided to the controller 270, or otherwise made available to the controller 270.
  • the controller 270 may also receive or store one or more inputs 282 identifying a reference lateral or radial impedance phase f nC .
  • the reference lateral or radial impedance phase ⁇ p rX may be an impedance phase of a lateral or radial piezoelectric actuator (the X-axis piezoelectric actuator including the piezoelectric actuators 148 and 150 in the embodiment described above) when the lateral or radial piezoelectric actuator vibrates at a lateral or radial resonant frequency of the vibration actuator 108 and the tool 228, such as a zero phase indicating an absence of reactance of the piezoelectric actuators 148 and 150, or may otherwise be a desired lateral or radial impedance phase.
  • the controller 270 may also receive or store one or more inputs 284 identifying a reference longitudinal or axial impedance phase ⁇ p rZ .
  • the reference longitudinal or axial impedance phase ⁇ p rZ may be an impedance phase of a longitudinal or axial piezoelectric actuator (the Z-axis piezoelectric actuator including the piezoelectric actuators 156 and 158 in the embodiment described above) when the longitudinal or axial piezoelectric actuator vibrates at a longitudinal or axial resonant frequency of the vibration actuator 108 and the tool 228, such as a zero phase indicating an absence of reactance of the piezoelectric actuators 156 and 158, or may otherwise be a desired longitudinal or axial impedance phase.
  • the reference impedance phases ⁇ p rX and ⁇ p rZ may be identified for a particular actuator and tool or varied, and identifications of the reference impedance phases ⁇ p rX and ⁇ p rZ may be stored in one or more data stores of the controller 270, encoded in one or more input signals provided to the controller 270, or otherwise made available to the controller 270.
  • the controller 270 may also receive or store one or more inputs 286 identifying the lateral or radial phase difference q g .
  • the lateral or radial phase difference q g may be identified or varied, and identifications of the lateral or radial phase difference q g may be stored in one or more data stores of the controller 270, encoded in one or more input signals provided to the controller 270, or otherwise made available to the controller 270.
  • the lateral or radial phase difference q g may define eccentricity of lateral or radial vibration in the first and second lateral or radial directions, such that lateral or radial vibration in the first and second lateral or radial directions may be elliptical for a lateral or radial phase difference q g that satisfies ⁇ p I2 ⁇ q g Further, a difference between an amplitude of vibrations in one lateral or radial direction and an amplitude of vibrations in another lateral or radial direction may cause elliptical lateral or radial vibrations.
  • the lateral or radial vibration controller 272 may include a phase detector 288 operable to detect the phase difference f c between I x and V x .
  • the phase detector 288 may receive one or more signals (such as a periodic signal) 290 representing V x , for example from V x but before a power amplifier 292 (which may include a high-voltage power amplifier 293 as shown in FIG. 18) and through a step-down amplifier 294 as shown in FIG. 17 (which may include an operational amplifier 295 as shown in FIG. 18).
  • the phase detector 288 may also receive one or more signals (such as a periodic signal) 296 representing I x , for example from a differential operational amplifier 298 measuring a drop of V x across a sensing resistor (or current sensing resistor) 300 as shown in FIG. 17.
  • signals such as a periodic signal
  • a differential operational amplifier 298 measuring a drop of V x across a sensing resistor (or current sensing resistor) 300 as shown in FIG. 17.
  • the phase detector 288 may include an analog comparator 302 that may produce a square- wave signal 304 from the one or more signals 296 representing I x .
  • the phase detector 288 may also include an analog comparator 306 that may produce a square- wave signal 308 from the one or more signals 290 representing V x .
  • An“exclusive or” (XOR) gate 310 may receive the square- wave signals 304 and 308.
  • a low-pass filter 312 may receive and low-pass filter the“exclusive or” of the square-wave signals 304 and 308 and may produce a phase-amplitude signal 314.
  • a flip-flop 316 may receive the square- wave signals 304 and 308 and produce a phase-sign signal 318.
  • the phase-amplitude signal 314 and the phase-sign signal 318 may collectively function as at least one phase signal 320 representing a measured or estimated phase difference f c between I x and V x .
  • An analog-to- digital converter (ADC) 322 may convert the at least one phase signal 320 to one or more digital signals.
  • the first lateral or radial vibration controller 272 may also include an X-axis controller 324 (which may be a proportional-integral (PI) controller, for example), which may receive one or more phase-difference signals 326 representing a difference between the reference lateral or radial impedance phase ⁇ p rX identified by the one or more inputs 282 and the measured or estimated phase difference f c identified by the at least one phase signal 320.
  • PI proportional-integral
  • the X-axis controller 324 may produce one or more excitation- frequency-increment signals 328 representing an excitation frequency increment f x in response to the difference (or error) between the reference lateral or radial impedance phase ⁇ p rX and the measured or estimated phase difference f c .
  • the X-axis signal generator 330 may include a pulse-width modulator (PWM) 334 that may receive that one or more X-axis excitation frequency signals 332, and that may produce a square-wave signal 336, which may be a 50% duty cycle square wave.
  • PWM pulse-width modulator
  • the X-axis signal generator 330 may also include a filter 338 that may filter the square-wave signal 336, and that may produce a sinusoidal signal 340.
  • the X-axis signal generator 330 may also include a pre-amplifier 342, which may receive the sinusoidal signal 340, and which may produce an amplified sinusoidal signal 344 by amplifying the sinusoidal signal 340.
  • the power amplifier 292 may receive and may amplify the amplified sinusoidal signal 344 to produce V x , which may be applied to the electrode 126.
  • the first lateral or radial vibration controller 272 may control vibration of the vibration actuator 108 in a first lateral or radial direction (such as a direction along the X axis in the embodiment described above) in response to a measured impedance of the piezoelectric actuators 148 and 150, more particularly by modulating a frequency of vibration of the vibration actuator 108 in the first lateral or radial direction in response to the measured impedance of the piezoelectric actuators 148 and 150 to cause the vibration actuator 108 to vibrate in the first lateral or radial direction at a frequency associated with a reference phase ⁇ p rX of the impedance of the piezoelectric actuators 148 and 150, which may be a frequency associated with an absence of reactance of the piezoelectric actuators 148 and 150.
  • the first lateral or radial vibration controller 272 may include an embedded digital signal processor 346 (such as a dSPACETM MicroLabBoxTM or another computer, processor circuit, or circuit) including the ADC 322, the X-axis controller 324, and the PWM 334. Further, the first lateral or radial vibration controller 272 may include a conditioning circuit 348 including the phase detector 288, the step-down amplifier 294, the differential amplifier 298, the filter 338, and the pre-amplifier 342. Further, the first lateral or radial vibration controller 272 may include a power circuit 350 including the power amplifier 292 and the sensing resistor 300.
  • an embedded digital signal processor 346 such as a dSPACETM MicroLabBoxTM or another computer, processor circuit, or circuit
  • the first lateral or radial vibration controller 272 may include a conditioning circuit 348 including the phase detector 288, the step-down amplifier 294, the differential amplifier 298, the filter 338, and the pre-amplifier 342.
  • the second lateral or radial vibration controller 274 may control vibration of the vibration actuator 108 in a second lateral or radial direction (such as a direction along the Y axis in the embodiment described above) in response to a measured impedance of the piezoelectric actuators 148 and 150, more particularly by modulating a frequency of vibration of the vibration actuator 108 in the second lateral or radial direction in response to the measured impedance of the piezoelectric actuators 148 and 150 to cause the vibration actuator 108 to vibrate in the second lateral or radial direction at a frequency associated with the reference phase ⁇ p rX of the impedance of the piezoelectric actuators 148 and 150, which may be a frequency associated with an absence of reactance of the piezoelectric actuators 148 and 150.
  • the longitudinal or axial vibration controller 276 may be similar to the X-axis signal generator 330 as described above but with respect to the Z axis instead of the X axis. Therefore, like the first lateral or radial vibration controller 272, the longitudinal or axial vibration controller 276 may control vibration of the vibration actuator 108 in a longitudinal or axial direction (such as a direction along the Z axis in the embodiment described above) in response to a measured impedance of the piezoelectric actuators 156 and 158, more particularly by modulating a frequency of vibration of the vibration actuator 108 in the longitudinal or axial direction in response to the measured impedance of the piezoelectric actuators 156 and 158 to cause the vibration actuator 108 to vibrate in the longitudinal or axial direction at a frequency associated with a reference phase f nZ of the impedance of the piezoelectric actuators 156 and 158, which may be a frequency associated with an absence of reactance of the piezoelectric actuators 156 and 158.
  • the vibration of the vibration actuator 108 in one lateral or radial direction may differ from the vibration of the vibration actuator 108 in another lateral or radial direction by a phase difference q g , but the vibration of the vibration actuator 108 in a longitudinal or axial direction may be controlled independently from the vibration of the vibration actuator 108 in the lateral or radial directions.
  • the controller 270 may control one or more of the voltages V X , V Y , and V z as described above or otherwise, and may therefore cause the piezoelectric actuators 148 and 150 to function as a first at least one piezoelectric actuator by vibrating the tool 228 in a first lateral or radial direction, cause the piezoelectric actuators 152 and 154 to function as a second at least one piezoelectric actuator by vibrating the tool 228 in a second lateral or radial direction orthogonal to (or, more generally, different from) the first lateral or radial direction, and cause the piezoelectric actuators 156 and 158 to function as a third at least one
  • piezoelectric actuator by vibrating the tool 228 in a longitudinal or axial direction orthogonal to (or, more generally, different from) the first and second lateral or radial directions.
  • controllers of alternative embodiments may include one or more circuits, such as one or more processor circuits that may include one or more microprocessors for example, that may be programmed or otherwise configured to control one or more of the voltages V x , V Y , and V z as described above or otherwise.
  • controllers of alternative embodiments may include one or more discrete logic circuits, one or more application- specific integrated circuits (“ASICs”), or both, for example.
  • ASICs application- specific integrated circuits
  • a tool system according to another embodiment is shown generally at 354 and includes a tool holder (including a rotary transformer) shown generally at 356 and a controller 358.
  • the tool holder 356 includes a vibration actuator housing 360 and a vibration actuator 362.
  • the vibration actuator housing 360 includes a stator portion 364 including a stator portion frame 365.
  • the vibration actuator housing 360 also includes a rotor portion 366 including a rotor portion frame 367 rotatable relative to the stator portion 364 about an axis of rotation 368.
  • the rotor portion 366 includes a tool interface 369 that may be similar to the tool interface 104.
  • the vibration actuator 362 includes a mounting flange 370 that may be similar to the mounting flanges 140 and 258 as described above, and that may be mounted to the rotor portion 366 of the vibration actuator housing 360 so that the vibration actuator 362 may be rotatable with the rotor portion 366 relative to the stator portion 364 about the axis of rotation 368.
  • the vibration actuator 362 also includes a piezoelectric actuator stack shown generally at 372 that may be similar to the piezoelectric actuator stack 146 as described above, and that may cause vibration of a tool 374 in three degrees of freedom as described above.
  • the tool 374 may be positioned and moved (for example, by rotation generally about the axis of rotation 368, by vibration by the vibration actuator 362, or by both) for drilling, milling, machining, or other operations for example, and the tool 374 may be generally elongate in a longitudinal direction generally along the axis of rotation 368.
  • the stator portion 364 includes a stator shown generally at 376, and the rotor portion 366 includes a rotor shown generally at 378.
  • the stator 376 includes a first stator coil 380, a second stator coil 382, and a third stator coil 384, each including a respective coil formed by a respective electrical conductor surrounding the axis of rotation 368.
  • the rotor 378 includes a first rotor coil 386, a second rotor coil 388, and a third rotor coil 390, each including a respective coil formed by a respective electrical conductor surrounding the axis of rotation 368.
  • the first stator coil 380, the second stator coil 382, the third stator coil 384, the first rotor coil 386, the second rotor coil 388, and the third rotor coil 390 may all be coaxial. Further, at least a portion of the first stator coil 380 surrounds at least a portion of the first rotor coil 386, at least a portion of the second stator coil 382 surrounds at least a portion of the second rotor coil 388, and at least a portion of the third stator coil 384 surrounds at least a portion of the third rotor coil 390.
  • a generally annular air gap 392 (which may be between about 0.5 mm and about 1 mm) radially separates the first stator coil 380 from the first rotor coil 386, the second stator coil 382 from the second rotor coil 388, and the third stator coil 384 from the third rotor coil 390.
  • a soft magnetic material with high magnetic permeability 394 may surround the first stator coil 380 except for the portion of the first stator coil 380 that faces the air gap 392.
  • a soft magnetic material with high magnetic permeability 396 may surround the second stator coil 382 except for the portion of the second stator coil 382 that faces the air gap 392.
  • a soft magnetic material with high magnetic permeability 398 may surround the third stator coil 384 except for the portion of the third stator coil 384 that faces the air gap 392.
  • a non-magnetic material 400 may be positioned between the first stator coil 380 and the second stator coil 382, and a non-magnetic material 402 may be positioned between the second stator coil 382 and the third stator coil 384.
  • a soft magnetic material with high magnetic permeability 404 (such as permalloy) may surround the first rotor coil 386 except for the portion of the first rotor coil 386 that faces the air gap 392.
  • a soft magnetic material with high magnetic permeability 406 (such as permalloy) may surround the second rotor coil 388 except for the portion of the second rotor coil 388 that faces the air gap 392.
  • a soft magnetic material with high magnetic permeability 408 (such as permalloy) may surround the third rotor coil 390 except for the portion of the third rotor coil 390 that faces the air gap 392.
  • the controller 358 may be electrically connected to a first electrode 410 to cause current to flow in the first stator coil 380, a second electrode 412 to cause current to flow in the second stator coil 382, and a third electrode 414 to cause current to flow in the third stator coil 384.
  • the controller 358 may be similar to the controller 270 as described above and may include one or more controllers that may induce respective currents in the first stator coil 380, the second stator coil 382, and the third stator coil 384. Changing current in the first stator coil 380 may change a generally toroidal magnetic field surrounding the first stator coil 380, which may induce a voltage in the first rotor coil 386.
  • the voltage induced in the first rotor coil 386 may be applied to piezoelectric actuators 416 and 418 of the piezoelectric actuator stack 372.
  • the piezoelectric actuators 416 and 418 may function similarly to the piezoelectric actuators 148 and 150 as described above and may individually or collectively function as a first lateral or radial piezoelectric actuator (for example, an X-axis piezoelectric actuator), and current in the first stator coil 380 may be referred to as a first lateral or radial actuation current.
  • the first stator coil 380 and the first rotor coil 386 may be associated with a first lateral or radial direction.
  • changing current in the second stator coil 382 may change a generally toroidal magnetic field surrounding the second stator coil 382, which may induce a voltage in the second rotor coil 388.
  • the voltage induced in the second rotor coil 388 may be applied to piezoelectric actuators 420 and 422 of the piezoelectric actuator stack 372.
  • the piezoelectric actuators 420 and 422 may function similarly to the piezoelectric actuators 152 and 154 as described above and may individually or collectively function as a second lateral or radial piezoelectric actuator (for example, a Y-axis piezoelectric actuator), and current in the second stator coil 382 may be referred to as a second lateral or radial actuation current.
  • the second stator coil 382 and the second rotor coil 388 may be associated with a second lateral or radial direction.
  • changing current in the third stator coil 384 may change a generally toroidal magnetic field surrounding the third stator coil 384, which may induce a voltage in the third rotor coil 390.
  • the voltage induced in the third rotor coil 390 may be applied to piezoelectric actuators 424 and 426 of the piezoelectric actuator stack 372.
  • the piezoelectric actuators 420 and 422 may function similarly to the piezoelectric actuators 156 and 158 as described above and may individually or collectively function as a longitudinal or axial piezoelectric actuator (for example, a Z-axis piezoelectric actuator), and current in the third stator coil 384 may be referred to as a longitudinal or axial actuation current.
  • the third stator coil 384 and the third rotor coil 390 may be associated with a longitudinal or axial direction.
  • FIG. 22 An equivalent circuit shown in FIG. 22 illustrates a lumped parameter model of current and voltage associated with the first lateral or radial direction.
  • a voltage V applied to the electrode 410 may cause a current I t to flow in the first stator coil 380.
  • the voltage V 2 induced the first rotor coil 386 may cause a current / 2 to flow in the first rotor coil
  • C 0 , L m , C m , and R m may have similar meanings in respect of the piezoelectric actuators 416 and 418 as described above in respect of the piezoelectric actuators 148 and 150.
  • where y is a transforming gain that may be measured.
  • of vibration may be
  • and I t and V 1 may be
  • V measured by an amplifier in a controller that may apply V to the electrode 410 as described herein, for example.
  • the first stator coil 380, the second stator coil 382, and the third stator coil 384 may have respective numbers of coils that may differ from respective numbers of coils of the first rotor coil 386, the second rotor coil 388, and the third rotor coil 390. Therefore, the stator 376 and the rotor 378 may function as a rotary transformer.
  • stator 376 may transfer power to the rotor 378 without requiring contact between the stator 376 and the rotor 378, and more generally without requiring slip rings or electrical conductors contacting or extending to a rotatable portion of the tool holder 356. Therefore, a rotary transformer including the stator 376 and the rotor 378 may be an alternative to slip rings and electrodes (or brashes) such as the slip rings 118, 120, and 122 and the electrodes 126, 128, and 130 as described above and may facilitate greater rotation speeds than slip rings.
  • slip rings and electrodes or brashes
  • the controller 358 may include a first lateral or radial vibration controller 427, which may be similar to the first lateral or radial vibration controller 272 as described above and that may control vibrations of the tool 374 in a first lateral or radial direction (such as a direction along the X axis in the embodiments described above).
  • the first lateral or radial vibration controller 427 includes a vibration observer 428, which includes a voltage Kalman filter 430 and a current Kalman filter 432.
  • the voltage Kalman filter 430 may produce a voltage phase signal and may therefore function as a phase detector.
  • the current Kalman filter 432 may produce a current phase signal and may therefore also function as a phase detector.
  • a signal representing a phase difference (or impedance phase) between the voltage phase detected by the voltage Kalman filter 430 and the current phase detected by the current Kalman filter 432 may be produced for use in a phase tracking loop, which may be similar to the phase tracking loop described above with reference to FIG. 17, for example.
  • the current Kalman filter 432 may also function as an amplitude detector and may also produce a current amplitude signal (which may represent vibration amplitude) for use in an amplitude control loop, which may also involve a controller (such as a PI controller) to control amplitude of vibration according to a difference between the vibration amplitude detected by the current Kalman filter 432 and a reference vibration amplitude ⁇ x ⁇ r , for example.
  • a controller such as a PI controller
  • the controller 358 may also include a second lateral or radial vibration controller that may be similar to the second lateral or radial vibration controller 274 or to the first lateral or radial vibration controller 427, but that may control vibrations of the tool 374 in a second lateral or radial direction (such as a direction along the Y axis in the embodiments described above), and the controller 358 may also include a longitudinal or axial vibration controller that may be similar to the longitudinal or axial vibration controller 276 or to the first lateral or radial vibration controller 427 but that may control vibrations of the tool 374 in a longitudinal or axial direction (such as a direction along the Z axis in the embodiments described above).
  • controllers such as the controller 358 may include both one or more phase tracking loops and one or more amplitude control loops. Such controllers are not limited to the embodiment of FIG. 19. Rather, for example, the controller 358 may be an alternative to the controller 270.
  • c is an amplitude of vibration in a first lateral or radial direction (such as a direction along the X axis in the embodiments described above), where y is an amplitude of vibration in a second lateral or radial direction (such as a direction along the Y axis in the embodiments described above),
  • p xx is a direct transforming gain in the first lateral or radial direction
  • xp yy is a direct transforming gain in the second lateral or radial direction
  • p xy and p yx are crosstalk transforming gains
  • I tx is a transforming current as described above for piezoelectric actuators that cause vibration in the first lateral or radial direction
  • I ty is a transforming current as described above for piezoelectric actuators that cause vibration in the second lateral or radial direction.
  • a controller according to an alternative embodiment is shown generally at 434 and includes a first lateral or radial vibration observer 436 that may be similar to the vibration observer 428 as described above with reference to FIG. 23, and that may detect phase and amplitude as described above with reference to FIG. 23 in reference to a first lateral or radial direction (such as a direction along an X axis, for example).
  • the controller 434 also includes a second lateral or radial vibration observer 438 that may also be similar to the vibration observer 428 as described above with reference to FIG. 23, and that may detect phase and amplitude as described above with reference to FIG.
  • the controller 434 may produce a phase measurement f c for use in a phase tracking loop, which may be similar to the phase tracking loop described above with reference to FIG. 17 or to the phase tracking loop described above with reference to FIG. 23, for example.
  • the controller 434 may also produce a first amplitude measurement
  • the controller 434 may also produce a second amplitude measurement ⁇ y ⁇ (according to Equation 5, for example) for use in a second amplitude control loop, which may also be similar to the amplitude control loop described above with reference to FIG. 23, for example.
  • the controllers 358 and 434 may cause at least one piezoelectric actuator to vibrate at least one tool in response to a measured impedance of the at least one piezoelectric actuator.
  • the controller 434 controls vibrations of a tool in two lateral or radial directions (such as directions along the X and Y axes in the embodiments described above), but the controller 434 may also include a longitudinal or axial vibration controller that may be similar to the longitudinal or axial vibration controller 276 or to the first lateral or radial vibration controller 427 but that may control vibrations of such a tool in a longitudinal or axial direction (such as a direction along the Z axis in the embodiments described above).
  • amplitude control loops in embodiments that include controllers such as the controller 434 may account for crosstalk effects.
  • controllers are not limited to the embodiment of FIG. 24. Rather, for example, the controller 434 may be an alternative to the controller 358.
  • vibration of a tool as described herein may facilitate drilling or otherwise cutting a material using the tool when the tool may also be rotated as described herein, for example in operations such as milling, drilling, or machining operations, for example.
  • Such operations may involve drilling holes or otherwise cutting or shaping a workpiece to produce a shape of a part.
  • vibration actuators such as those described herein may cause vibrations simultaneously in two lateral or radial directions (for example, in directions along X and Y axes) without causing vibrations in a longitudinal or axial direction (for example, in a direction along the Z axis).
  • vibration actuators such as those described herein may cause vibrations in a longitudinal or axial direction (for example, in a direction along the Z axis) without causing vibrations in any lateral or radial directions (for example, in directions along X and Y axes).
  • vibration actuators such as those described herein may cause vibrations in simultaneously two lateral or radial directions (for example, in directions along X and Y axes) and in a longitudinal or axial direction (for example, in a direction along the Z axis). Still other embodiments may differ.
  • embodiments such as those described above may vibrate a tool in two lateral or radial directions, which may cause elliptical vibration in the two lateral or radial directions.
  • elliptical vibration may cause intermittent tool- workpiece contact, which may facilitate cutting a composite material (for example) with the tool with reduced fiber delamination or fracture when compared to other methods of cutting such a material.
  • embodiments such as those described above may control a frequency of vibration in response to a measured impedance of at least one piezoelectric actuator, which may allow the at least one piezoelectric actuator to cause vibration at a resonant frequency without necessarily requiring additional sensors.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)

Abstract

L'invention concerne un appareil pouvant comprendre : au moins un premier actionneur piézoélectrique permettant de faire vibrer un outil dans une première direction latérale ; et au moins un second actionneur piézoélectrique permettant de faire vibrer l'outil dans une seconde direction latérale. Un autre appareil peut comprendre au moins quatre corps de support soutenant un actionneur de vibration destiné à une vibration par rapport à un boîtier d'actionneur de vibration. Un autre appareil peut comprendre au moins un dispositif de commande permettant, au moins, d'amener au moins un actionneur piézoélectrique à faire vibrer un outil en réponse à une impédance mesurée dudit actionneur piézoélectrique. Un autre appareil peut comprendre : une bobine de rotor rotative permettant de transférer au moins une partie d'une tension à au moins un actionneur piézoélectrique ; et une bobine de stator permettant d'induire la tension dans la bobine de rotor. Au moins une section de la bobine de stator peut entourer au moins une section de la bobine de rotor.
PCT/CA2019/050416 2018-04-04 2019-04-04 Procédés et appareils provoquant la vibration d'au moins un outil WO2019191848A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140773A (en) * 1990-02-14 1992-08-25 Brother Kogyo Kabushiki Kaisha Ultrasonic machine and its machining method
US6286747B1 (en) * 2000-03-24 2001-09-11 Hong Kong Polytechnic University Ultrasonic transducer
US7352110B2 (en) * 2003-07-04 2008-04-01 Peter Hess Tool head comprising piezoelectric actuators
US20120045976A1 (en) * 2009-01-05 2012-02-23 Roser Jochen Handheld electric machine tool
US20160129542A1 (en) * 2014-11-07 2016-05-12 Tongtai Machine & Tool Co., Ltd. Machine tool of high-frequency vibration and control method of sensing/feedback signals thereof
WO2017005917A1 (fr) * 2015-07-08 2017-01-12 Sauer Gmbh Dispositif pour générer la vibration ultrasonore d'un outil et pour mesurer des paramètres de vibrations

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5140773A (en) * 1990-02-14 1992-08-25 Brother Kogyo Kabushiki Kaisha Ultrasonic machine and its machining method
US6286747B1 (en) * 2000-03-24 2001-09-11 Hong Kong Polytechnic University Ultrasonic transducer
US7352110B2 (en) * 2003-07-04 2008-04-01 Peter Hess Tool head comprising piezoelectric actuators
US20120045976A1 (en) * 2009-01-05 2012-02-23 Roser Jochen Handheld electric machine tool
US20160129542A1 (en) * 2014-11-07 2016-05-12 Tongtai Machine & Tool Co., Ltd. Machine tool of high-frequency vibration and control method of sensing/feedback signals thereof
WO2017005917A1 (fr) * 2015-07-08 2017-01-12 Sauer Gmbh Dispositif pour générer la vibration ultrasonore d'un outil et pour mesurer des paramètres de vibrations

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