JP2007223017A - Ultrasonic rotation machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic machining machine having a rotating tool having high machining accuracy and high reliability. <P>SOLUTION: The machining device is provided with: a motor 1 for rotating a stainless rotary shaft 2; a bearing 3 for rotatably supporting the rotary shaft 2; and a non-illustrated stainless case for fixing the bearing 3. In the rotary shaft 2, a slip ring 13 fixed to the rotary shaft 2 is provided. A brush 14 for supplying ultrasonic AC power is in contact with the slip ring 13. Ultrasonic AC voltage is applied to the brush 14 by an ultrasonic oscillator 16 through a lead wire 15. By holding an aluminum cylindrical holder 11 in a holding part by a chuck device 5, an end mill to be the rotating tool 6 is fixed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic processing apparatus that applies ultrasonic vibration to a rotating tool to process glass, ceramic, silicone, cemented carbide, and the like, which are objects to be processed.

Recently, in order to process so-called difficult-to-process materials, a method of applying ultrasonic vibration to a tool or an object to be processed 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 advantages that the frictional resistance between the workpiece and the tool is reduced, so that the thermal distortion of the machined surface is reduced, the machining accuracy is increased, and the life of the cutting tool is extended. ing.

The 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

However, 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, the chuck device holding the tool and the tool are rubbed with each other by ultrasonic vibration, and seizure occurs.
Furthermore, due to the ultrasonic vibration, the holding force of the chuck device that holds the tool sometimes becomes small, and there is a problem that the tool stops when a mechanical load is applied to the tool during processing.

  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, but compared with the tool, 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.

  An object of the present invention is to provide an ultrasonic machining apparatus having a rotary tool with high accuracy and high reliability.

  The present invention is an ultrasonic machining apparatus having a rotating tool, wherein the ultrasonic vibrator is joined to the tool body, and the ultrasonic vibrator is located at a position held by the chuck device. It is.

  The present invention is also an ultrasonic oscillation circuit having a resonance tracking circuit for tracking the natural frequency as a power source for applying electric power to the ultrasonic transducer bonded to the tool.

  Since the ultrasonic processing apparatus of the present invention has high rotational accuracy and can be rotated at high speed, high-accuracy and high-speed processing is possible.

  FIG. 2 is a front view showing a basic configuration showing the first embodiment. A motor 1 for rotating the stainless steel rotating shaft 2 is provided. There is a bearing 3 for rotatably supporting the rotating shaft 2, and there is a stainless steel case (not shown) for fixing the bearing 3. The rotating shaft 2 has a slip ring 13 fixed to the rotating shaft 2. The slip ring 13 is in contact with a brush 14 for supplying ultrasonic AC power. An ultrasonic AC voltage is applied to the brush 14 from an ultrasonic oscillator 16 through a lead wire 15. And the end mill which is the rotary tool 6 is fixed by hold | maintaining the cylindrical holder 11 made from aluminum in a holding | maintenance part with the chuck | zipper apparatus 5. FIG.

  Details of the rotary tool 6 will be described with reference to the plan view of FIG. The rotary tool 6 is a carbide end mill having an outer diameter of 1 mm and a length of 50 mm.

  Then, as will be described with reference to a plan view showing a partial cross section of FIG. 4, a cylindrical piezoelectric ceramic 12 that is an ultrasonic vibrator is joined to the rotary tool 6 using an epoxy resin. Then, an aluminum cylindrical holder 11 which is further anodized and insulated by an epoxy resin is joined to the outside thereof. The cylindrical piezoelectric ceramic 12 is polarized in the radial direction. Silver electrodes are provided on the inner and outer surfaces. The cylindrical piezoelectric ceramic 12 has an outer diameter of 2.0 mm, an inner diameter of 1.0 mm, and a length of 25 mm.

  The rotary tool 6 is divided into a working part 9 including a blade and a holding part 10 that is held and fixed by the chuck device 5.

  Then, the cylindrical aluminum holder 11 in the holding unit 10 is held by the chuck device 5. Here, it is important that the holding portion 10 held by the chuck device 5 has the piezoelectric ceramic 12 at a position.

  The slip ring 13 and the cylindrical piezoelectric ceramic 12 are electrically connected by a lead wire (not shown). Below the rotary tool 6 are a table 8 and a workpiece 7 for fixing the workpiece 7.

  Next, the operation method of this ultrasonic processing apparatus will be described with reference to FIG. First, the power of the motor 1 is turned on to rotate the rotating shaft 2. Next, the ultrasonic oscillator 16 capable of tracking the resonance frequency is turned on, and the ultrasonic AC voltage of the natural frequency at which the work part vibrates in the optimum vibration mode on the cylindrical piezoelectric ceramic 12 via the brush 14 and the slip ring 13. Is applied. By applying the ultrasonic alternating voltage, only the working part 9 of the rotary tool 6 can be vibrated efficiently.

When the chuck device 5 has a mass several times larger than that of the rotary tool 6 and the position of the chuck device 5 corresponds to an end for fixing the rotary tool 6, the rotary tool 6 has a fixed end on one side. It becomes the longitudinal vibration of the rod. Non-Patent Document 3 describes in detail the longitudinal vibration of a bar whose one side is a fixed end. Therefore, the holding part 10 and the chuck device 5 of the rotary tool 6 corresponding to the fixed end of vibration are of course small in vibration displacement and are almost vibration nodes.
Osamu Taniguchi, “Industrial Vibration”, Corona Inc., April 15, 1996, p325-359

  As described above, since the vibration hardly propagates to the chuck device 5, there is almost no vibration loss, so that the vibration of the required working portion 9 can be excited with a small electric power. Therefore, since the temperature rise of the machine part 9 can be reduced, the machining accuracy can be improved.

  Further, since the ultrasonic vibration has an effect of reducing the friction coefficient, when the holding unit 10 or the chuck device 5 vibrates, the holding force of the rotary tool 6 of the chuck device 5 decreases, and the workpiece 7 is being processed. Slip between the rotary tool 6 and the chuck device 5 due to the load, the rotary tool 6 is broken, and the workpiece 7 is damaged. Since the vibration of the rotating tool 6 of the present invention hardly propagates to the holding unit 10 or the chuck device 5 as described above, the force for holding the rotating tool 6 of the chuck device 5 is hardly feared.

  Of course, since vibration hardly propagates to the rotating shaft 2, there is almost no risk of damage due to vibration of the bearing 3 or the rotating shaft 2.

  As described above, since only the machine part 9 of the rotary tool 6 can be vibrated, a highly reliable ultrasonic machining apparatus with high machining accuracy can be provided.

  Here, how the vibration of the rotary tool is caused by the position where the rotary tool 6 is held by the chuck device 5 was calculated using the finite element method.

  Calculation was performed for the rotary tool 6 shown in the cross-sectional view of FIG. The rotary tool 6 has a diameter of 5 mm and a length of 100 mm, and is made of tool steel. The ultrasonic vibrator is a piezoelectric ceramic 12, and has an outer diameter of 7 mm, an inner diameter of 5 mm, and a length of 60 mm. The outer holder 11 of the piezoelectric ceramic has an outer diameter of 9 mm, an inner diameter of 7 mm, and a length of 60 mm. Further, on the outside, a part which is a part of the chuck device has an outer diameter of 11 mm, an inner diameter of 9 mm and a length of 30 mm. The calculation is performed with the degree of freedom of the outer peripheral portion having an outer diameter of 11 mm being constrained. In order to shorten the calculation time, a 30 degree model of a cylinder was used.

  FIG. 5A is a schematic diagram of a case in which the upper end portion of the holder 11 is held by the chuck device 5, and FIG. 6A is a result of calculating the vibration mode by a finite element method. The natural frequency is about 21 KHz, and the holder 11 hardly vibrates.

  FIG. 5B is a schematic diagram of a case in which the center portion of the holder 11 is held by the chuck device 5, and FIG. 6B is a result of calculating the vibration mode by the finite element method. The natural frequency is about 25 KHz, and the holder 11 hardly vibrates.

  FIG. 5C is a schematic view of a case in which the central portion of the holder 11 is held by the chuck device 5, and FIG. 6C is a result of calculating the vibration mode by the finite element method. The natural frequency is about 28 KHz, and the holder 11 hardly vibrates.

  As described above, no matter where the holding unit 10 is held by the chuck device 5, the chuck device 5 becomes a substantially fixed end, and a vibration mode in which the machine part vibrates longitudinally is obtained. Then, the natural frequency changes depending on the position of the holding portion held by the chuck device 5. Naturally, if the drill wears out and the length of the work part changes, the natural frequency also changes. Therefore, it can be seen that a tracking circuit for tracking the natural frequency is necessary.

  Another configuration of the rotary tool 6 is shown in the perspective view of FIG. In the rotary tool 6, four grooves are provided in a work part 9 and a cylindrical stainless steel holder 11, and a piezoelectric ceramic 12 is joined to the grooves. The chuck device holds the holder 11. Lead wires can be easily drawn from piezoelectric ceramics.

  The above configuration is particularly effective when the rotary tool 6 is enlarged. If the piezoelectric ceramic 12 becomes large, it becomes difficult to manufacture and it becomes difficult to balance rotation. In such a case, the piezoelectric ceramic 12 can be miniaturized and the shape is rectangular, so that the manufacture becomes easy and the rotation balance becomes easy. Furthermore, the rotational balance of the rotary tool can be easily made by cutting stainless steel.

  FIG. 8 is a front view including a partial cross section showing a basic configuration showing the second embodiment. A hollow motor 1 for rotating a stainless steel hollow rotating shaft 2 is provided. There is a bearing 3 for rotatably supporting the rotating shaft 2, and there is a stainless case 21 for fixing the bearing 3. The rotary shaft 2 includes a rotary transformer 4 a on the rotation side fixed to the rotary shaft 2. In the vicinity of the rotary transformer 4a, there is a fixed rotary transformer 4b. A fixing plate to which the rotary transformer 4b on the fixed side is attached is not shown in order to simplify the drawing. A capacitor 20 is connected in series to the fixed-side rotary transformer 4b so that electric power can be efficiently supplied at a target frequency. A capacitor can be connected to the rotary transformer 4a for the same purpose, but it is not preferable to attach it to the rotary side in consideration of the rotation balance. There is a chuck device 5 which is a holding device for fixing the rotary tool 6 to the rotary shaft 2. The chuck device 5 holds the rotary tool 6 of the present invention. The rotary transformer 4 a on the rotation side and the piezoelectric ceramic 12 that is an ultrasonic vibrator fixed to the rotary tool 6 are electrically coupled by a lead wire 15. Below the rotating tool 6 is a workpiece 7 fixed to a table 8.

  The details of the rotary tool 6 are shown in the perspective view of FIG. The rotary tool 6 includes a holding unit 10 held by the chuck device 5 and a work unit 9. A grindstone is joined to the tip of the working unit 9. The grindstone uses diamond as a binder and metal as a binder. The holding part 11 has a cylindrical piezoelectric ceramic 12 bonded to the outside of the stainless steel shaft by an epoxy resin, and further has a cylindrical holder 11 made of stainless steel on the outside thereof. Silver electrodes are provided on the outer and inner surfaces of the cylindrical piezoelectric ceramic 12. The polarization direction is the radial direction. Further, an inorganic insulator is thinly baked on the outer electrode in contact with the stainless steel holder 11.

  FIG. 10 shows a sectional side view of a cylindrical piezoelectric ceramic 12 and a stainless steel cylindrical holder 11. The length of the cylindrical piezoelectric ceramic 12 is longer than that of the cylindrical holder 11, and a lead wire 15 is joined to the tip thereof by soldering.

  Next, the operation method of this ultrasonic processing apparatus will be described with reference to FIG. First, the power of the motor 1 is turned on to rotate the rotating shaft 2. Next, the ultrasonic oscillator 16 is turned on, and an ultrasonic AC voltage is applied to the cylindrical piezoelectric ceramic 12 through the rotary transformer 4a on the rotating side and the rotary transformer 4b on the fixed side. By applying an ultrasonic AC voltage having a natural frequency that vibrates substantially in the longitudinal vibration mode only in the work part, the work part 9 of the rotary tool 6 mainly vibrates.

  The vibration mode of the rotary tool is the same as that described with reference to FIGS. 5 and 6. However, since the additional mass as a grindstone is joined to the tip of the rotary tool, the natural frequency is lowered.

  As a result, the holding unit and the chuck device are not seized by the ultrasonic vibration, and the rotating tool is not loosened due to a decrease in the frictional force between the holding unit and the chuck device.

  The above processing is ultrasonic cutting, and the frictional resistance between the object to be processed and the tool is reduced, so the thermal distortion of the processed surface is reduced, the processing accuracy is increased, and the life of the cutting tool is extended. It has the advantages such as.

  Of course, since vibration hardly propagates to the rotating shaft, there is almost no risk of damage due to vibration of the bearing or the rotating shaft.

  As described above, it is possible to provide an ultrasonic machining apparatus with high machining accuracy and high reliability by exciting vibration only to the machine tool 9 of the rotary tool.

  When the piezoelectric ceramic is bonded directly to the rotary tool, the expensive piezoelectric ceramic must be discarded as the rotary tool is consumed. Therefore, the structure shown in the exploded view of FIG. 11 was devised. First, an end mill, which is a rotating tool, is joined to a stainless steel-made cylinder 22 having a thread on its outer periphery using an epoxy resin.

  On the other hand, a piezoelectric ceramic 12 is joined to a stainless steel cylinder 23 whose inner periphery is cut, and a stainless steel cylindrical holder 11 is joined to the outside thereof. The surface of the piezoelectric ceramic in contact with the stainless steel cylindrical holder 11 is insulated with an organic material.

  Next, a stainless steel screw joined to the end mill is screwed into the structure including the cylindrical holder 11 made of stainless steel. FIG. 12 shows an integrated assembled sectional side view. When the end mill is consumed, the end mill and the screw are discarded, and the configuration including the stainless steel cylindrical holder 11 is reused. By doing so, the running cost can be reduced.

  In the above description, the piezoelectric ceramic is used as the ultrasonic vibrator. However, for example, a magnetostrictive vibrator may be used.

  The ultrasonic processing apparatus of the present invention can be used in various processing apparatuses that process a workpiece by rotating a tool.

It is a cross-sectional top view which shows the conventional ultrasonic grinding apparatus. It is a front view which shows the basic composition which shows the 1st Embodiment of this invention. It is a front view which shows a rotary tool. It is a front view including the partial cross section which shows the rotary tool which joined the piezoelectric ceramic. It is sectional drawing explaining a holding | maintenance part and a chuck apparatus position. It is the figure which calculated the vibration mode by the finite element method about the structure of FIG. It is the perspective view which joined the piezoelectric ceramic to the holder which has a slot in a rotary tool. It is a front view which shows the basic composition which shows the 2nd Embodiment of this invention. It is a perspective view which shows the rotary tool which has a piezoelectric ceramic which has a grindstone at the front-end | tip. It is sectional drawing which shows the detail of the piezoelectric ceramic and holder of FIG. It is an exploded view showing a rotary tool having a piezoelectric ceramic that can be assembled. It is an assembly drawing which shows the cross section of the rotary tool of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Rotating shaft 3 Bearing 4 Rotary transformer 5 Chuck device 6 Rotating tool 7 Work object 8 Table 9 Work part 10 Holding part 11 Holder 11
DESCRIPTION OF SYMBOLS 12 Piezoelectric ceramic 13 Slip ring 14 Brush 15 Lead wire 16 Ultrasonic oscillator 17 Grinding wheel 18 Groove 19 Ultrasonic vibrator 20 Capacitor 21 Case 22 Cylinder 23 with thread on the outer periphery 23 Cylinder with thread on the inner periphery

Claims (2)

  In an ultrasonic processing apparatus having a rotating tool, an ultrasonic vibrator is bonded to a tool body, and the ultrasonic vibrator is in a position grasped by a chuck device. . It is an ultrasonic oscillation circuit having a resonance tracking circuit for tracking the natural frequency as a power source for applying electric power to the ultrasonic transducer bonded to the tool.

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