JP2008183698A - Ultrasonic tool holder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool holder performing ultrasonic-machining with high machining accuracy and high reliability. <P>SOLUTION: This ultrasonic tool holder 1 has a cylindrical shape and has a distal end part on a side for holding a tool 5. A titanium front mass part 6 has a cylindrical shape having a level difference and has a chuck bar 3 at a distal end. Piezoelectric ceramics 2a and 2b are inserted into the front mass part 6 and are fastened by a titanium cylindrical rear mass part 7. A polyethylene insulating ring 9 is located in a bronze electrode 8a and the front mass part 6 to prevent the electrode 8a held between the piezoelectric ceramics 2a and 2b from being brought into contact with the front mass part 6. The front mass part 6 is provided with a collet holder part 21 to hold a collet 20. A part of an end mill being the tool 5 fitted in the stainless collet 20 is put in the collet holder part 21, and the end mill is fixed and held by a collet nut 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic tool holder for holding a tool.

  Recently, in order to process a so-called difficult-to-process material, a method of applying ultrasonic vibration to a tool or a workpiece and processing has been frequently used. Such a processing method is called ultrasonic cutting, and is described in detail in Non-Patent Document 1, for example. Ultrasonic cutting has the advantage that the frictional resistance between the workpiece and the tool is reduced, so that the thermal distortion of the processed surface is reduced, the processing accuracy is increased, and the life of the cutting tool is extended.

  A conventional ultrasonic grinding apparatus is described in detail in Non-Patent Document 2. The ultrasonic grinding apparatus shown in FIG. 1 also has a motor for rotating a rotary shaft, and a slip ring and an ultrasonic vibrator are provided on the rotary shaft. Further, a booster, a horn, and a diamond grindstone as a grinding tool are connected to the rotating shaft. In addition, a bearing for rotatably supporting is arranged. An ultrasonic oscillator and a brush for applying an ultrasonic alternating voltage to the ultrasonic vibrator are provided.

The general operation method of the above ultrasonic grinding apparatus is as follows. First, when the motor is operated, an ultrasonic alternating voltage is applied from an ultrasonic oscillator to a slip ring that rotates through a brush almost simultaneously. The AC voltage applied to the slip ring is applied to the ultrasonic vibrator, and the ultrasonic vibrator vibrates ultrasonically. This ultrasonic vibration propagates through the booster and horn, and then propagates to the grinding wheel, which is a grinding tool.
Ultrasonic Handbook Editorial Committee, “Ultrasonic Handbook”, Maruzen Co., Ltd., August 1999, p679-684 Japan Electromechanical Industry Association, "Ultrasonic Engineering", Corona Co., Ltd., 1993, p218-229

  In the ultrasonic grinding apparatus of FIG. 1, when an ultrasonic vibrator is attached to the rotating shaft, the rotating shaft vibrates ultrasonically, so that the ultrasonic vibration propagates to the bearing and the bearing may be damaged. Also, abnormal wear may occur on the rotating shaft and the bearing, which may increase wear. Furthermore, since a Langevin type ultrasonic transducer, which is an ultrasonic transducer approximately equal to the diameter of the rotating shaft, is joined to the rotating shaft, the weight increases, the rotational inertia increases, and the structure becomes unsuitable for high-speed rotation. Further, the rotation becomes unstable due to the shape error and weight imbalance of the ultrasonic transducer bonded to the rotating shaft, the rotating device breaks down, and the processing accuracy decreases.

  As another problem, when the rotation of the rotating shaft reaches 10,000 rotations or more per minute, the brush and slip ring power supply device consumes excessive brushes and cannot supply power in a short time.

  In addition, since the tool vibrates with the chuck device as a fixed end, the drive frequency must be changed depending on the length of the tool from the fixed end. However, the Langevin type ultrasonic vibrator, rotating shaft and horn Since the mass is large, vibration can be efficiently excited mainly only at the natural frequency of the Langevin type ultrasonic vibrator. Therefore, there is also a problem that it is impossible to excite vibrations optimal for the tool.

  Furthermore, since an ultrasonic vibrator, a booster, and a horn are attached to the rotating shaft, a normal polishing apparatus cannot be used. For this reason, a new apparatus must be manufactured.

  An object of the present invention is to provide an ultrasonic processing method having high accuracy and high reliability.

  The present invention relates to a tool holder for holding a tool, wherein the tool holder has a piezoelectric ceramic, and the tool holder has a chuck bar that coincides with the center axis of the tool, and a rotary transformer on the rotating side is connected to the chuck bar. Is.

  In the present invention, the inner diameter D2 is 0.2 or more times D1 with respect to the outer diameter D1 of the piezoelectric ceramic.

  The present invention also makes the diameter of the chuck rod equal to or less than the inner diameter D2 of the piezoelectric ceramic and greater than 0.2 times D2.

  The ultrasonic tool holder of the present invention is used in a rotary machining machine such as a drilling machine or a milling machine to perform ultrasonic machining, thereby enabling high-precision and high-speed machining.

  FIG. 2 is a front view showing a basic configuration of the ultrasonic tool holder 1 showing the first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line AA of FIG. The ultrasonic tool holder 1 has a cylindrical shape, and the tip end is the side that holds the tool 5. The front mass portion 6 made of titanium has a cylindrical shape with a step, and further has a chuck bar 3 at the tip. The piezoelectric ceramics 2a and 2b are sandwiched between the two and tightened by a cylindrical rear mass portion 7 made of titanium. The insulating ring 9 made of polyethylene is positioned on the electrode 8a and the front mass portion 6 so that the phosphor bronze electrode 8a sandwiched between the piezoelectric ceramics 2a and 2b and the front mass portion 6 do not come into contact with each other. The front mass portion 6 is provided with a collet holder portion 21 for holding the collet 20. A part of the end mill, which is the tool 5 fitted in the stainless steel collet 20, enters the collet holder portion 21, and the end mill is fixedly held by the collet nut 22.

  Here, the shapes of the piezoelectric ceramic 2 and the chuck bar 3 suitable for the ultrasonic tool holder 1 of the present invention will be described. The ultrasonic vibrations at the positions of the front mass portion 6 and the rear mass portion 7 at the upper and lower positions perpendicular to the ring surface between the outer diameter D1 and the inner diameter D2 of the piezoelectric ceramic 2 are strong. On the other hand, the chuck rod 3 has a diameter equal to or smaller than the inner diameter D2 of the piezoelectric ceramic 2 in order to minimize the propagation of ultrasonic vibration as much as possible. However, if the chuck bar 3 becomes too thin, the structure becomes weak and unnecessary movement occurs in the tool 5. Therefore, the shape of the chuck bar 3 is preferably the same as or smaller than D2 of the piezoelectric ceramic 2 and 0.2 times or more of D2. The inner diameter D2 of the piezoelectric ceramic is preferably small to increase the energy of ultrasonic vibration, but considering the structural strength of the chuck bar 3, it is 0.2 times or more the outer diameter D1 of the piezoelectric ceramic.

  The chuck rod 3 is fixedly held by the chuck device at the vibration node, but the chuck device is not shown in order to simplify the drawing. As the chuck device, there are mechanical holding methods such as a drill chuck, a collet chuck, and a taper fit. Further, depending on the position of the node portion, the rotating shaft and the chuck rod may be screwed together. Further, a chuck rod may be joined to the rotating shaft by welding.

  A rotary rotary 15a made of soft ferrite for transmitting ultrasonic power is joined to the chuck rod 3 with an epoxy resin. And the surface of one side is similarly joined to the rear mass part 7 with the epoxy resin. Since the rear mass portion 7 is almost a node, the rotary transformer 15a on the rotating side is joined with an epoxy resin. Therefore, the rotary transformer 15a on the rotation side cannot be joined to the rear mass portion 7 in the vibration mode in which the rear mass portion 7 is not a node.

  The ultrasonic tool holder 1 has a structure of a Langevin type ultrasonic transducer. Here, the depth of the groove 4 is about one fifth of the length of the ultrasonic transducer. The polarization direction of the piezoelectric ceramics 2a and 2b is the plate thickness direction.

  Next, the vibration mode of the ultrasonic tool holder 1 will be described. In this vibration mode, almost only the end mill vibrates in the first order. The front mass portion 6, the piezoelectric ceramics 2a, 2b, and the rear mass portion 7 of the ultrasonic tool holder 1 are almost longitudinal vibration nodes, and the chuck rod 3 connected thereto is also almost a vibration node. Therefore, even if the chuck bar 3 is held and fixed, the longitudinal vibration of the ultrasonic tool holder 1 is hardly affected. Such a vibration mode is considered to be due to the fact that the connection position of the chuck bar 3 is at a position of a vibration node.

  The result of calculating the frequency response using the finite element method is shown in FIG. First, the frequency response between 10 KHz and 100 KHz is shown in FIG. The horizontal axis is frequency, and the vertical axis is current. Here, the first vibration mode described above is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. Only the end mill performs primary longitudinal vibration with the front mass portion 6 as a fixed end. Most of the chuck bars 3 are nodes. In order to be in such a vibration mode, the mass of the front mass portion 6 needs to be several times as large as that of the end mill. As a result, the center of gravity of the configuration including the end mass and the ultrasonic tool holder 1 in the front mass portion 6 is required. There is.

  In the vibration mode as described above, the longitudinal vibration of the tool 5 is hardly attenuated even when the chuck bar 3 is restrained. Since the chuck bar 3 is a node, unnecessary vibrations are not propagated to the mechanical device through the portion holding the chuck bar 3. Further, since unnecessary vibration is not propagated, vibration energy can be reduced, so that the amount of generated heat can be reduced, and the processing accuracy can be improved. Furthermore, since the power supply can be reduced, the power supply can be reduced, so that the equipment cost can be reduced.

  Next, the second vibration mode is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. This is a primary longitudinal vibration with the center of gravity of the ultrasonic tool holder 1 located in the front mass portion 6 approximately as a node, and the chuck bar 3 also has a node, but the vibration mode shown in FIG. The vibration node is small.

  FIG. 5 is a front view including a partial cross section showing a basic configuration of an ultrasonic polishing apparatus using the ultrasonic tool holder 1. A motor 12 for rotating the stainless steel rotating shaft 11 is provided. There is a bearing 13 for rotatably supporting the rotating shaft 11, and there is a stainless case 14 for fixing the bearing 13. A fixed-side rotary transformer 15b is fixed to the tip of the case 14 with a bolt (not shown). The rotation-side rotary transformer 15a fixed to the chuck rod 3 is disposed at a position opposite to the center axis of the fixed-side rotary transformer 15b. The distance between the rotary rotary transformer 15a and the fixed rotary transformer 15b can be determined when the chuck bar 3 is connected to the rotary shaft 11. The piezoelectric ceramics 2a and 2b are electrically coupled by lead wires 17b and 17c and electrodes 8a and 8b. An end mill is fixedly held on the ultrasonic tool holder 1 by a collet 20. Below that, there is a work 18 fixed to the table 19.

  Next, a method for operating the machining apparatus using the ultrasonic tool holder 1 will be described with reference to FIG. First, the motor 12 is turned on to rotate the rotating shaft 11. Next, the ultrasonic oscillator 16 is turned on, and an ultrasonic AC voltage is applied to the piezoelectric ceramics 2a and 2b via the lead wire 17a, the fixed rotary transformer 15b, the rotary rotary transformer 15a, and the electrodes 8a and 8b. Only the tool 5 mainly vibrates by applying an ultrasonic AC voltage having a natural frequency in which only the tool 5 vibrates in the longitudinal vibration mode.

  Since electric power can be supplied from the fixed rotary transformer 15b to the rotary rotary transformer 15a in a non-contact manner, by immediately changing the configuration in which the rotary rotary transformer 15a, the ultrasonic tool holder 1 and the tool are integrated, another type of transformer can be immediately used. The tool 5 can be switched. Even if the rotary shaft 11 rotates at a high speed exceeding tens of thousands of revolutions per minute, there is no problem because power can be supplied in a non-contact manner.

  In addition, since the ultrasonic processing machine can be obtained simply by attaching the fixed-side rotary transformer 15b to the existing rotary processing machine, the ultrasonic processing machine can be manufactured at low cost.

  The ultrasonic machining using the ultrasonic tool holder 1 can excite the ultrasonic vibration only in the ultrasonic tool holder 1 and the tool 5, so that the machining accuracy is high, the tool life is increased, and the machining speed is increased. It has the advantage of increasing.

  In addition to the above-mentioned end mill, the tool used in the present invention includes a drill with a shaft, a reamer, and the like.

  FIG. 6 is a front view showing a basic configuration of an ultrasonic tool holder 1 showing a second embodiment of the present invention, and FIG. 7 is a cross-sectional view taken along line AA of FIG. The ultrasonic tool holder 1 has a cylindrical shape, and the tip end is the side that holds the tool 5. The front mass portion 6 made of stainless steel has a cylindrical shape with a step, and further has a chuck bar 3 at the tip. Piezoelectric ceramics 2a and 2b are sandwiched between them and tightened by a cylindrical rear mass portion 7 made of stainless steel. The insulating ring 9 made of polyethylene is positioned on the electrode 8a and the front mass portion 6 so that the phosphor bronze electrode 8a sandwiched between the piezoelectric ceramics 2a and 2b and the front mass portion 6 do not come into contact with each other. The front mass portion 6 is provided with a screw hole for attaching a collet holder portion 21 for holding the collet 20.

  The collet holder portion 21 having a male screw is inserted into the screw hole of the front mass portion 6 and screwed, so that the front mass portion 6 and the collet holder portion 21 are integrated. Thus, by manufacturing the collet holder part 21 separately, it can respond to the collet 20 of various sizes. Then, a part of the end mill fitted in the stainless steel collet 20 enters, and the end mill is fixedly held by the collet nut 22.

  The chuck rod 3 is joined with a rotary transformer 15a on the rotating side made of soft ferrite for transmitting ultrasonic power.

  The ultrasonic tool holder 1 has a structure of a Langevin type ultrasonic transducer. Here, the depth of the groove 4 is about two-fifths of the length of the ultrasonic transducer.

  The polarization directions of the piezoelectric ceramics 2a and 2b are indicated by arrows in the perspective view of FIG. The electrode of the piezoelectric ceramic 2a is the upper surface electrode 8c, and the lower electrode is divided into two electrodes 8a and 8b. Piezoelectric ceramics 2b are divided electrodes 8d and 8e. The bottom is a full surface electrode, which is 8f. The electrode 8c and the electrode 8f are electrically connected. Further, bending vibration is excited in the ultrasonic tool holder 1 by the polarization direction of the piezoelectric ceramic and the voltage application method shown in FIG. A voltage is applied to the piezoelectric ceramics 2a and 2b via lead wires 17a and 17b connected to the ultrasonic oscillator 16.

  FIG. 10 shows the result of calculating the frequency response of the above vibration using the finite element method. First, the frequency response between 10 KHz and 100 KHz is shown in FIG. The horizontal axis is frequency, and the vertical axis is current.

  Here, the first vibration mode is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. Bending vibration having nodes in the front mass portion 6 and the rear mass portion 7 is performed. The chuck bar 3 also has a portion that becomes a node. Therefore, even if the knot portion of the chuck bar 3 is fixed and held, the vibration of the end mill is not greatly affected.

  Here, the second vibration mode is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. Almost only the end mill performs bending vibration with the front mass portion 6 as a fixed end. In order to enter such a vibration mode, the mass of the front mass portion 6 needs to be several times or more that of the end mill.

  Even if the chuck bar 3 is restrained, the bending vibration of the tool is hardly attenuated. Since the chuck bar is a node, unnecessary vibration is not propagated to the mechanical device through the portion holding the chuck bar. Further, since unnecessary vibration is not propagated, vibration energy can be reduced, so that the amount of generated heat can be reduced, and the processing accuracy can be improved. Furthermore, since the power supply can be reduced, the power supply can be reduced, so that the equipment cost can be reduced.

  Here, an electrode pattern for exciting elliptical vibration at the tip of the end mill, a polarization pattern, and a method for applying a voltage will be described with reference to the perspective view of FIG. 11 and FIG. The arrow in FIG. 11 faces the plate thickness direction. The upper electrode 8e of the piezoelectric ceramic 2a is a full surface electrode, and the lower electrode is divided into four electrodes 8a, 8b, 8c and 8d. The polarization direction is an arrow direction indicated by a dotted line. The upper side of the piezoelectric ceramic 2b is divided into four electrodes 8f, 8g, 8h, and 8i. The lower electrode 8j is a full surface electrode, and the polarization direction is an arrow direction indicated by a solid line.

  FIG. 12 shows a phosphor bronze electrode placed between the piezoelectric ceramic 2a and the piezoelectric ceramic 2b, and is positioned according to the electrode pattern of FIG. Then, as shown in the figure, an elliptical vibration is excited at the tip of the end mill by applying voltages of cos phase and sin phase.

  Furthermore, an electrode pattern for exciting torsional vibration at the tip of the end mill, a polarization pattern, and a method for applying a voltage will be described with reference to the perspective view of FIG. 13 and FIG. The arrow in FIG. 13 points in the circumferential direction. The piezoelectric ceramic 2a is divided into four parts and joined and integrated with an epoxy resin. The same is true for the upper and lower surfaces. The piezoelectric ceramic 2b is also divided into four parts and joined together by an epoxy resin. The same is true for the upper and lower surfaces. However, the polarization direction is opposite to that of the piezoelectric ceramic 2a.

  An electrode 8b made of phosphor bronze on the piezoelectric ceramic 2a, an electrode made of phosphor bronze inserted between the piezoelectric ceramic 2a and the piezoelectric ceramic 2a, and an electrode 8c made of phosphor bronze below the piezoelectric ceramic 2b. Then, as shown in FIG. 14, a voltage is applied from the ultrasonic oscillator 16 to the electrode 8a through the lead wire 17a, and a ground potential is applied to the electrodes 8b and 8c through the other lead wire 17b. As a result, torsional vibration is generated, and the torsional vibration is propagated to the end of the end mill.

  Even in the various vibration modes described above, even if the chuck bar 3 is restrained, the vibration of the tool 5 is hardly attenuated. Since the chuck bar 3 is a node, unnecessary vibrations are not propagated to the mechanical device through the portion holding the chuck bar 3. Further, since unnecessary vibration is not propagated, vibration energy can be reduced, so that the amount of generated heat can be reduced, and the processing accuracy can be improved. Furthermore, since the power supply can be reduced, the power supply can be reduced, so that the equipment cost can be reduced.

  FIG. 15 is a front view showing a basic configuration of an ultrasonic tool holder 1 showing a third embodiment of the present invention, and FIG. 16 is a cross-sectional view taken along line AA of FIG. The ultrasonic tool holder 1 has a cylindrical shape, and the tip end is the side that holds the tool 5. The front mass portion 6 made of titanium has a cylindrical shape having a female screw on the central axis, and further has a female screw on the tip surface for screwing the drill chuck portion 24. Piezoelectric ceramics 2a and 2b are sandwiched between them, and a titanium rear mass 7 has a male screw at the center and is tightened by a disk having a chuck bar 3 on the opposite surface.

  The drill chuck portion 24 having a male screw is put into the female screw of the front mass portion 6, and the screwed front mass portion 6 and the drill chuck portion 24 are integrated. Thus, by manufacturing the drill chuck portion 24 separately, various sizes of drills can be handled.

  The chuck rod 3 is joined with a rotary transformer 15a on the rotating side made of soft ferrite for transmitting ultrasonic power.

  The ultrasonic tool holder 1 has a structure of a Langevin type ultrasonic transducer. The polarization direction of the piezoelectric ceramics 2a and 2b is the plate thickness direction. Longitudinal vibration is excited in the ultrasonic tool holder 1 by the polarization direction of the piezoelectric ceramics 2a and 2b and the voltage application method.

  Next, the vibration mode of the ultrasonic tool holder 1 will be described. In the ultrasonic tool holder 1, only a drill vibrates longitudinally. Therefore, if the chuck bar 3 is held and fixed, the vibration of the ultrasonic tool holder 1 is hardly affected.

  FIG. 17 shows the result of calculating the frequency response of the above vibration using the finite element method. First, the frequency response between 10 KHz and 100 KHz is shown in FIG. The horizontal axis is frequency, and the vertical axis is current.

  Here, the first vibration mode is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. The front mass portion 6, the piezoelectric ceramics 2a and 2b, and the rear mass portion 7 are almost nodes, and only the end mill vibrates greatly. The chuck bar 3 also has a portion that becomes a node. Therefore, even if the knot portion of the chuck bar 3 is fixed and held, the vibration of the end mill is not greatly affected.

  Here, the second vibration mode is shown in FIG. The calculated vibration displacement of the ultrasonic tool holder 1 is indicated by a vector. The primary longitudinal vibration is free at both ends with the position of the piezoelectric ceramic 2 as a node. The end mill vibrates greatly, and more than half of the chuck bar 3 is a node. This is considered to be due to the fact that the diameter of the chuck bar 3 is about 0.3 times D1 compared to the outer diameter D1 of the piezoelectric ceramic. That is, the proportion of the vibration energy of the piezoelectric ceramic 2 propagating to the chuck rod 3 is small.

  As described above, by controlling the shape of the ultrasonic tool holder 1, a mode in which only the tool 5 vibrates can be excited. Further, although the mode in which the entire ultrasonic tool holder 1 vibrates longitudinally can be excited, the knot portion of the chuck bar tends to be small. In addition, as the frequency increases, the node tends to decrease. Therefore, the frequency of the voltage applied to the piezoelectric element is desirably 100 KHz or less.

  Even if the groove portion 4 is not provided in the rear mass portion 7, even if the chuck bar 3 is fixed and held by controlling the shape of the ultrasonic tool holder 1, the vibration of the tool is not greatly affected.

  As described above, even if the groove portion 4 is not provided in the rear mass portion 7 and the chuck bar 3 is restrained, the vibration of the tool 5 is hardly attenuated. Since the chuck bar 3 is a node, unnecessary vibrations are not propagated to the mechanical device through the portion holding the chuck bar 3. Further, since unnecessary vibration is not propagated, vibration energy can be reduced, so that the amount of generated heat can be reduced, and the processing accuracy can be improved. Furthermore, since the power supply can be reduced, the power supply can be reduced, so that the equipment cost can be reduced.

  Here, the arrangement of the rotary transformer 15 will be described. FIG. 18 shows a rotary shaft 15 joined to a rotary shaft 15a. In order to apply a voltage to the piezoelectric ceramics 2a and 2b of the ultrasonic tool holder 1, a lead is taken from the rotary transformer 15a attached to the rotary shaft 11. Must be connected by lines 17a, 17b. In order to replace the ultrasonic tool holder 1, the lead wires 17a and 17b cannot be fixed to the rotary shaft 11 using an epoxy resin. For this reason, the lead wires 17a and 17b vibrate when the rotating shaft 11 rotates at high speed, and there is a risk of disconnection.

  In FIG. 19, a rotary transformer 15a on the rotating side is joined to a chuck rod, and a voltage can be applied to the piezoelectric ceramics 2a and 2b via lead wires 17a and 17b joined to the rear mass portion 7 with an epoxy resin. For this reason, there is no fear of disconnection of the lead wires 17a and 17b even when the rotary shaft 11 rotates at high speed. In addition, since there is no need to touch the lead wires 17a and 17b even when the ultrasonic tool holder 1 is replaced, there is no fear of disconnection. And replacement work can be done easily. As described above, the advantage of joining the rotary rotary transformer 15a to the ultrasonic tool holder 1 is great.

  Although the shape of the ultrasonic tool holder has been described as a cylindrical shape, it is needless to say that the shape may be a regular polygonal column shape that is not a columnar shape but a regular triangular prism or more.

  The ultrasonic tool holder of the present invention can be ultrasonically used in various machining apparatuses.

It is a schematic explanatory drawing which shows the conventional ultrasonic polishing apparatus. It is a front view which shows the ultrasonic rotation holder of the 1st Embodiment of this invention. It is sectional drawing in the AA line of FIG. It is the figure which computed the frequency characteristic and vibration mode of the structure of FIG. 2 by the finite element method. It is sectional drawing which shows the structure of the grinding | polishing apparatus which attached the ultrasonic rotation holder of FIG. It is a front view which shows the ultrasonic rotation holder of the 2nd Embodiment of this invention. It is sectional drawing in the AA of FIG. It is a perspective view which shows the piezoelectric ceramic used for FIG. It is a figure which shows the application method of the voltage to the piezoelectric ceramic of FIG. It is the figure which computed the frequency characteristic and vibration mode of the structure of FIG. 6 by the finite element method. It is a perspective view which shows another piezoelectric ceramic used for FIG. It is a figure which shows the application method of the voltage to the piezoelectric ceramic of FIG. It is a perspective view which shows another piezoelectric ceramic used for FIG. It is a figure which shows the application method of the voltage to the piezoelectric ceramic of FIG. It is a front view which shows the ultrasonic rotation holder of the 3rd Embodiment of this invention. It is sectional drawing in the AA of FIG. It is the figure which computed the frequency characteristic and vibration mode of the structure of FIG. 15 by the finite element method. It is sectional drawing which attached the rotary transformer to the rotating shaft. It is sectional drawing which attached the rotary transformer to the ultrasonic tool holder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic tool holder 2 Piezoelectric ceramic 3 Chuck rod 4 Groove part 5 Tool 6 Front mass part 7 Rear mass part 8 Electrode 9 Insulating ring 10 Screw screw 11 Rotating shaft 12 Motor 13 Bearing 14 Case 15 Rotary transformer 16 Ultrasonic oscillator 17 Lead wire 18 Workpiece 19 Table 20 Collet 21 Collet holder part 22 Collet nut 23 Epoxy resin 24 Drill chuck part

Claims (3)

  In a tool holder for holding a tool, the tool holder has a piezoelectric ceramic, the tool holder has a chuck bar that coincides with the center axis of the tool, and a rotary transformer on the rotating side is connected to the chuck bar. To do. 2. The tool holder according to claim 1, wherein the inner diameter D <b> 2 is 0.2 times or more of D <b> 1 with respect to the outer diameter D <b> 1 of the piezoelectric ceramic.   2. The tool holder according to claim 1, wherein the diameter of the chuck bar is equal to or less than the inner diameter D2 of the piezoelectric ceramic and greater than 0.2 times D2.

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