Ultrasonic vibration processing device

Provided is an ultrasonic vibration processing device which can suppress vibration of components due to an ultrasonic vibrator and can perform processing using ultrasonic vibration in a preferable manner; the ultrasonic vibration processing device includes: a housing (10); an ultrasonic vibrator (20) including a horn portion (21A) to which a tool holder (70) is detachably attached and a piezoelectric element (23), the ultrasonic vibrator having a rear end located at a node of ultrasonic vibration and being supported inside the housing (10) so as to be rotatable; a connecting portion (30) stored in the housing (10) so as to be rotatable together with the ultrasonic vibrator (20); a motor (40) connected to the connecting portion (30); and a non-contact power supply unit (50) including a primary transformer (51) and a secondary transformer (52), the primary transformer (51) being fixed to the housing (10) and including a primary coil (51B) that receives high frequency power from an external power supply, the secondary transformer (52) being connected to the rear end of the ultrasonic vibrator (20) with a clearance maintained between the secondary transformer (52) and the primary transformer (51) and including a secondary coil (52B) that supplies an induced electromotive force to the piezoelectric element (23).

TECHNICAL FIELD

The present invention relates to an ultrasonic vibration processing device.

BACKGROUND ART

An ultrasonic vibration processing device in Patent Literature 1 includes a housing, a spindle, a tool holder, an ultrasonic vibrator, and a non-contact power supply unit. The spindle is supported inside the housing so as to be rotatable around a rotation axis. The tool holder is connected to a distal end of the spindle, and a cutting/grinding tool is attached to the tool holder. The ultrasonic vibrator vibrates the cutting/grinding tool via the tool holder. The non-contact power supply unit supplies high frequency power to the ultrasonic vibrator. The non-contact power supply unit includes a primary transformer, a secondary transformer, and a clearance maintaining mechanism for maintaining a set clearance between the primary transformer and the secondary transformer. The primary transformer has a primary coil which receives high frequency power from an external power supply. The secondary transformer has a secondary coil which generates induced electromotive force between itself and the primary coil by electromagnetic induction.

In the ultrasonic vibration processing device, the clearance maintaining mechanism maintains the set clearance between the primary transformer and the secondary transformer even when a length of the spindle changes due to heat generated from the ultrasonic vibrator or the like. Accordingly, in the ultrasonic vibration processing device, induced electromotive force is generated at the secondary coil of the non-contact power supply unit in a stable manner. Therefore, the ultrasonic vibration processing device can supply high frequency power to the ultrasonic vibrator in a stable manner, with the result that processing using ultrasonic vibration can be performed in a preferable manner.

CITATION LIST

Patent Literature

Patent Literature 1: JP 2011-131343 A

SUMMARY OF INVENTION

Technical Problems

According to the ultrasonic vibration processing device in Patent Literature 1, however, a drive motor for rotationally driving the spindle is constituted of a stator provided on an inner circumferential surface of the housing and a rotor provided on an outer circumferential surface of the spindle. Accordingly, the length of the spindle increases, and therefore ultrasonic vibration energy may not be efficiently transmitted to the tool side.

Furthermore, in the ultrasonic vibration processing device in Patent Literature 1, it is not considered that the secondary transformer is vibrated due to vibration of the ultrasonic vibrator. Therefore, in the ultrasonic vibration processing device, induced electromotive force generated at the secondary coil may be unstable due to the vibration of the secondary transformer by the ultrasonic vibrator.

The present invention has been developed in view of the above-described conventional circumstances. A problem to be solved by the present invention is to provide an ultrasonic vibration processing device that can suppress vibration of components due to an ultrasonic vibrator and can perform processing using ultrasonic vibration in a preferable manner.

Solutions to Problems

An ultrasonic vibration processing device according to a first invention includes:

a housing;

an ultrasonic vibrator including a horn portion having a distal end portion to which a tool holder is detachably attached and a piezoelectric element held at an intermediate portion in a direction of a rotation axis, the ultrasonic vibrator having a rear end located at a node of ultrasonic vibration generated by the piezoelectric element, the ultrasonic vibrator being supported inside the housing so as to be rotatable around the rotation axis;

a connecting portion having a front end portion connected to a rear end portion of the ultrasonic vibrator, and stored in the housing so as to be rotatable around the rotation axis together with the ultrasonic vibrator;

a rotational driving unit connected to a rear end portion of the connecting portion; and

a non-contact power supply unit including a primary transformer and a secondary transformer, the primary transformer being fixed to the housing and including a primary coil that receives high frequency power from an external power supply, the secondary transformer being connected to a rear end of the ultrasonic vibrator with a clearance maintained between the secondary transformer and the primary transformer, the secondary transformer being configured to be rotated around the rotation axis together with the ultrasonic vibrator and including a secondary coil that supplies an induced electromotive force generated between the secondary coil and the primary coil by electromagnetic induction, to the piezoelectric element.

An ultrasonic vibration processing device according to a second invention includes:

a housing;

an ultrasonic vibrator including a horn portion having a distal end portion to which a tool holder is detachably attached and a piezoelectric element held at an intermediate portion in a direction of a rotation axis, the ultrasonic vibrator being supported inside the housing so as to be rotatable around the rotation axis;

a connecting portion having a front end portion connected to a rear end portion of the ultrasonic vibrator, and stored in the housing so as to be rotatable around the rotation axis together with the ultrasonic vibrator, the connecting portion including a spline bearing having an insertion opening opened at a rear end of the connecting portion;

a rotational driving unit including a spline shaft that is inserted into the spline bearing through the insertion opening of the connecting portion and rotatable around the rotation axis, the rotational driving unit being connected to a rear end portion of the connecting portion; and

a non-contact power supply unit including a primary transformer and a secondary transformer, the primary transformer being fixed to the housing and including a primary coil that receives high frequency power from an external power supply, the secondary transformer being connected to a rear end of the ultrasonic vibrator with a clearance maintained between the secondary transformer and the primary transformer, the secondary transformer being configured to be rotated around the rotation axis together with the ultrasonic vibrator and including a secondary coil that supplies an induced electromotive force generated between the secondary coil and the primary coil by electromagnetic induction, to the piezoelectric element.

DESCRIPTION OF EMBODIMENTS

A preferred embodiment of the present invention will be described.

In the ultrasonic vibration processing device of the second invention, the spline bearing may be located at a node of ultrasonic vibration generated by the piezoelectric element.

In the ultrasonic vibration processing device of the second invention, surface hardening treatment may be performed on an inner circumferential surface of the spline bearing and an outer circumferential surface of the spline shaft.

The ultrasonic vibration processing device of the first invention and the second invention may further include a reflecting member that is held between the rear end of the ultrasonic vibrator and the secondary transformer and has a specific acoustic impedance different from a specific acoustic impedance of the ultrasonic vibrator.

In the ultrasonic vibration processing device of the first invention and the second invention, a specific acoustic impedance of the connecting portion and a specific acoustic impedance of the ultrasonic vibrator may be different from each other.

An ultrasonic vibration processing device according to a first embodiment of the present invention will be described with reference to the drawings.

First Embodiment

As shown inFIG. 1, an ultrasonic vibration processing device according to the first embodiment includes a housing10, an ultrasonic vibrator20, a connecting portion30, a motor40as a rotational driving unit, a non-contact power supply unit50, a reflecting member60, and a tool holder70.

The housing10includes a housing body11having a cylindrical shape, cover members13and15attached to respective ends of the housing body11, and a fixing member17attached inside the housing body11and fixing a primary transformer51described later inside the housing body11. The housing body11includes a first storage portion C1for storing the ultrasonic vibrator20, the non-contact power supply unit50and others described later, and a second storage portion C2for storing a spline bearing31and a part of a joint portion33constituting the connecting portion30described later. The second storage portion C2is continuous with a rear of the first storage portion C1via a step extending outward. (The front-rear direction corresponds to the down-up direction inFIG. 1; this definition is applicable to the following description.) An inside space of the first storage portion C1has a columnar shape. A side surface of the first storage portion C1is formed with a first air hole12through which air flows in. An inside space of the second storage portion C2has a columnar shape having a larger diameter than that of the shape of the inside space of the first storage portion C1. A side surface of the second storage portion C2is formed with a second air hole14through which air flows out. The air is allowed to flow in through the first air hole12and flow out through the second air hole14, thereby suppressing temperature rise inside the housing10caused by heat generated from the ultrasonic vibrator20which is supported within the housing10so as to be rotatable around a rotation axis X as described later.

A central portion of the cover member13attached to the front end of the housing body11is provided with an opening13A having a circular shape. The opening13A has an inner diameter slightly larger than an outer diameter of a front end portion of the ultrasonic vibrator20described later, so that a clearance is provided between the opening13A and the front end portion of the ultrasonic vibrator20. Air inside the housing10is allowed to flow out through the clearance. According to this configuration, temperature rise inside the housing10can be suppressed. A central portion of the cover member15attached to the rear end of the housing body11is provided with an opening15A having a circular shape. The opening15A has an inner diameter slightly larger than an outer diameter of a drive shaft43of the motor40described later. The fixing member17has a disk shape, and a central portion thereof is provided with an opening17A having a circular shape. An outer diameter of the fixing member17is substantially equal to an inner diameter of the second storage portion C2. The opening17A of the fixing member17has an inner diameter slightly larger than an outer diameter of a shaft portion33B of the joint portion33of the connecting portion30described later. The fixing member17is engaged with a step portion provided at a boundary between the second storage portion C2and the first storage portion C1, thereby being attached inside the housing body11.

As shown inFIGS. 1 and 2, the ultrasonic vibrator20includes a main body21, four piezoelectric elements23, a holding portion25, and a tightening portion27. The main body21includes a horn portion21A having a distal end portion to which the tool holder70is detachably attached. The piezoelectric elements23are stacked and disposed at the rear of a rear end of the main body21. The holding portion25is disposed at the rear of a rear end of the piezoelectric elements23. The tightening portion27is disposed at the rear of a rear end of the holding portion25and holds the piezoelectric elements23and the holding portion25between the main body21and the tightening portion27. Each of the main body21, the holding portion25, and the tightening portion27is made of stainless steel.

The main body21has a substantially columnar shape. Two opposite surfaces21D at a distal end portion of the main body21are cut into flat surfaces to be held by a tool such as a spanner. In the horn portion21A formed in a distal end portion of the main body21, an insertion hole21B is formed extending rearward on the central axis and opened forward. An inner side surface of the insertion hole21B is formed as an inclined surface such that diameter of the insertion hole21B is slightly reduced toward a depth direction. The insertion hole21B is formed with a female screw portion21C which is continued from a central portion of a bottom surface of the insertion hole21B and extends rearward on the central axis furthermore, the main body21is formed with a female screw portion (not shown) which is opened rearward at a central portion of a rear end of the main body21and extends forward on the central axis from the rear end.

Each of the piezoelectric elements23has an annular shape having an outer diameter slightly smaller than the diameter of the main body21, and four piezoelectric elements23are stacked. An inner diameter of each of the piezoelectric elements23is larger than an outer diameter of a shaft portion (not shown) of the tightening portion27described later. The holding portion25has an annular shape having the same outer diameter as the outer diameter of the main body21. An inner diameter of the holding portion25is larger than an outer diameter of a shaft portion (not shown) of the tightening portion27described later. The tightening portion27is constituted of a tightening main body27A and a shaft portion (not shown). The tightening main body27A has a shape obtained by cutting two opposite surfaces of a columnar body having an outer diameter slightly larger than each diameter of the main body21and the holding portion25into a flat surface. Accordingly, the tightening main body27A of the tightening portion27can be held by a tool such as a spanner and rotated. The tightening main body27A is formed with a female screw portion27B opened rearward at a central portion of a rear end of the tightening main body27A and extending forward on the central axis of the tightening main body. A shaft portion (not shown) extends forward on the central axis from a central portion of a front surface of the tightening main body27A. A distal end of the shaft portion (not shown) is formed with a male screw portion.

In the ultrasonic vibrator20having the above configuration, the four stacked piezoelectric elements23are disposed at the rear end of the main body21, and the holding portion25is disposed at the rear end of the piezoelectric elements23. In this state, the shaft portion (not shown) of the tightening portion27is inserted into the holding portion25and the four piezoelectric elements23, and the male screw portion formed in the shaft portion (not shown) of the tightening portion27is screwed into the female screw portion (not shown) opened at the rear end of the main body21. As a result, the ultrasonic vibrator20is constructed in such a manner that the center axes of the main body21, the four piezoelectric elements23, the holding portion25, and the tightening portion27are arranged on one straight line. As shown inFIG. 1, the ultrasonic vibrator20is constructed such that the rear end of the ultrasonic vibrator20(the rear end of the tightening portion27) is located at a node F1of ultrasonic vibration generated by the piezoelectric elements23. According to this configuration, as will be described later, vibration generated by the piezoelectric elements23can be prevented from being easily transmitted to the secondary transformer52connected to the rear end of the ultrasonic vibrator20.

The ultrasonic vibrator20is supported inside the housing10so as to he rotatable around the rotation axis X as described below.

The ultrasonic vibrator20is stored in the first storage portion C1of the housing10. In this case, a front end portion of the ultrasonic vibrator20protrudes from the opening13A of the cover member13attached to the front end of the housing body11. In the state where the ultrasonic vibrator20is thus disposed, the ultrasonic vibrator20is supported inside the housing10so as to be rotatable around the rotation axis X by two ball bearings81and82disposed at positions separated in the front-rear direction and between an inner wall surface of the first storage portion C1and an outer circumferential surface of the main body21of the ultrasonic vibrator20.

The two ball bearings81and82are disposed at positions corresponding to nodes F2and F3, respectively, of ultrasonic vibration generated by the piezoelectric elements23. In other words, the two ball bearings81and82are disposed apart from each other by a half wave length of the ultrasonic vibration. Accordingly, the two ball bearings81and82can support the ultrasonic vibrator20in a rotatable state without receiving vibration in the rotation axis X direction generated by the piezoelectric elements23, so that the ultrasonic vibrator20can be rotated in a preferable manner.

The ball bearing81disposed on the front side holds, between an outer ring of the ball bearing81and the cover member13attached to the front end of the housing body11, a first spacer83having a cylindrical shape and in contact with the inner wall surface of the first storage portion C1. The ball bearings81and82hold, between their respective outer rings, a second spacer84having a cylindrical shape and in contact with the inner wall surface of the first storage portion C1. The ball bearing82disposed on the rear side holds, between an outer ring of the ball bearing82and the fixing member17attached inside the housing body11, a third spacer85having a cylindrical shape and in contact with the inner wall surface of the first storage portion C1. The two ball bearings81and82are thus positioned.

The connecting portion30is constituted of the joint portion33and the spline bearing31as shown inFIG. 1andFIGS. 3(A) and 3(B). The joint portion33is made of a titanium alloy. The titanium alloy has a specific acoustic impedance different from that of stainless steel forming the tightening portion27and others of the ultrasonic vibrator20. Accordingly, even when the connecting portion30is connected to the ultrasonic vibrator20as described later, a part of vibration generated by the ultrasonic vibrator20is reflected on the boundary between the joint portion33of the connecting portion30and the tightening portion27of the ultrasonic vibrator20, so that the vibration is not easily transmitted toward the connecting portion30. The spline bearing31is made of carbon steel. The joint portion33is constituted of a head portion33A and a shaft portion33B. The head portion33A has a flat plate shape, and the external shape as viewed from the side where the shaft portion33B extends is an octagonal shape obtained by cutting off corners of a square. The shaft portion33B extends from a central portion of a front surface of the head portion33A. The shaft portion33B has a substantially columnar shape, and has a distal end portion having a reduced diameter and formed with a male screw portion33C.

The spline bearing31is constituted of a bearing portion31A and a flange portion31B. The hearing portion31A has a substantially cylindrical shape, and a through hole penetrating a center of the hearing portion31A is formed such that an inner diameter of the front end portion is larger than the inner diameter on the rear side. In the bearing portion31A, inner teeth31C are formed on an inner circumferential surface of a portion with a small inner diameter. The inner circumferential surface of the bearing portion31A where the inner teeth31C are formed is coated with diamond-like carbon (DLC). The flange portion31B has an annular shape extending outward from an outer circumferential edge of a front end of the bearing portion. The flange portion31B includes four through holes31D formed at equal intervals on an identical circumference. The spline bearing31and the joint portion33are connected by bolts (not shown) inserted through the through holes31D.

The connecting portion30is stored inside the housing10so as to be rotatable around the rotation axis X together with the ultrasonic vibrator20as described below.

The connecting portion30is mainly stored in the second storage portion C2of the housing10. The shaft portion33B of the joint portion33of the connecting portion30is inserted through the opening17A of the fixing member17attached to the housing body11and through a through hole penetrating respective centers of a primary core51A of the primary transformer51and a secondary core52A of the secondary transformer52of the non-contact power supply unit50described later, and then the male screw portion33C formed at the distal end portion of the shaft portion33B of the joint portion33is screwed into the female screw portion27B formed at a rear end of the tightening main body27A of the ultrasonic vibrator20. In this manner, the connecting portion30is connected to the ultrasonic vibrator20, and stored inside the housing10so as to be rotatable around the rotation axis X.

As shown inFIG. 1, in a state where the connecting portion30is connected to the ultrasonic vibrator20and stored in the second storage portion C2, a central portion of the spline bearing31of the connecting portion30in the rotation axis X direction is located at a node F0of ultrasonic vibration generated by the piezoelectric elements23. Therefore, vibration of the spline bearing31in the rotation axis X direction is small, which can make it hard for the vibration to be transmitted to the motor40connected to the spline bearing31by the spline shaft45as described later.

As shown inFIG. 1, the motor40includes a motor body41, and a drive shaft43projecting from the motor body41. The motor40has a brake function. Accordingly, the motor40is capable of maintaining a constant holding torque. Outer teeth43A are formed on an outer circumferential surface of a distal end portion of the drive shaft43as shown inFIGS. 3(A) and 3(B), thereby constituting the spline shaft45. The outer circumferential surface of the spline shaft45is coated with DLC. The spline shaft45is inserted into the spline bearing31through an insertion opening opened at a rear end of the connecting portion30as shown inFIG. 1andFIGS. 3(A) and 3(B). The motor40is connected to the connecting portion30in this manner.

As described above, the connecting portion30and the motor40are connected to each other by the spline bearing31and the spline shaft45. Accordingly, although the connecting portion30is vibrated in the rotation axis X direction by the ultrasonic vibrator20, the vibration is not easily transmitted to the motor40. Furthermore, since the inner circumferential surface of spline bearing31and the outer circumferential surface of spline shaft45are coated with DLC friction between the spline bearing31and the spline shaft45is reduced, and abrasion resistance between the spline bearing31and spline shall45improves. Accordingly, the ultrasonic vibrator20and others in the ultrasonic vibration processing device can be rotated in a preferable manner for a long time.

As shown inFIGS. 1 and 4, the non-contact power supply unit50includes the primary transformer51and the secondary transformer52. The primary transformer51includes the primary core51A and a primary coil51B. The primary core51A has an annular shape, and a front surface thereof is formed with a groove51C going round on a circumference of a circle. The primary coil51B is wound in a number of rounds along the groove51C of the primary core51A. The primary coil51B is connected to an external power supply via an electric wire W1, and receives high frequency power from the external power supply. The primary transformer51is fixed to a front surface of the fixing member17fixed inside the housing10. In this case, the primary transformer51is fixed to the fixing member17such that a through hole penetrating a center of the primary core51A is aligned with the opening17A of the fixing member17. Accordingly, a central axis of the primary core51A and a center of the opening of the fixing member17are located on the rotation axis X.

The secondary transformer52includes the secondary core52A and a secondary coil52B. The secondary core52A has an annular shape, and a rear surface of the secondary core52A is formed with a groove52C going round on a circumference of a circle. The secondary coil52B is wound in a number of rounds along the groove52C of the secondary core52A. The secondary transformer52is connected to the rear end of the ultrasonic vibrator20which is supported inside the housing10so as to be rotatable around the rotation axis X, via the reflecting member60described later. In this state, a clearance S is formed between the primary transformer51and the secondary transformer52. The secondary coil52B is connected to the piezoelectric elements23via an electric wire W2. The secondary coil52B supplies an induced electromotive force generated between itself and the primary coil51B by electromagnetic induction, to the piezoelectric elements23.

The reflecting member60is made of acrylic. Acrylic has a specific acoustic impedance different from that of stainless steel forming the tightening portion27and others of the ultrasonic vibrator20. The reflecting member60is disk-shaped, and a through hole is formed at a central portion of the reflecting member60. The reflecting member60has the same outer diameter as the outer diameter of the tightening main body27A of the tightening portion27of the ultrasonic vibrator20. An inner diameter of the through hole of the reflecting member60is slightly larger than an outer diameter of the shaft portion33B of the joint portion33of the connecting portion30. The reflecting member60is bonded to and held between the rear end of the ultrasonic vibrator20and the secondary transformer52. Accordingly, the reflecting member60reflects vibration of the ultrasonic vibrator20toward the ultrasonic vibrator20, which can make it hard for the vibration to be transmitted to the secondary transformer52.

The tool holder70is constituted of a chuck portion71, a connecting portion72, and an insertion portion73as shown inFIG. 1. The chuck portion71has a truncated cone shape having a diameter reduced toward a distal end of the chuck portion71, and has an insertion hole71A formed on the central axis into which a tool80such as an end mill is inserted. The tool holder70is a shrink fit holder in which the tool is attached to the chuck portion71by shrink-fitting. The connecting portion72has a shape of a hexagonal column continuous with a rear end of the chuck portion71. The insertion portion73is constituted of a first insertion portion73A, a second insertion portion73B, and a male screw portion73C. The first insertion portion73A has a columnar shape continuous with a rear end of the connecting portion72. The first insertion portion73A has an outer diameter smaller than an inner diameter of an opening of the insertion hole21B formed in the horn portion21A of the ultrasonic vibrator20. The second insertion portion73B has a truncated cone shape continuous with a rear end of the first insertion portion73A, and has a diameter slightly reduced toward the rear. The male screw portion73C is continuous with a central portion of a rear end of the second insertion portion73B.

Tool replacement of the tool holder70can be automatically performed by a rotary driving device not-shown which is rotated in a state where the connecting portion72is inserted in a hexagonal hole formed in the rotary driving device from below so that the male screw portion73C of the insertion portion73is tightened to or loosened from the female screw portion21C of the insertion hole21B formed in the horn portion21A of the ultrasonic vibrator20. In the automatic replacement of the tool, a torque for tightening the tool holder by the rotary driving device can be set constant by setting a holding torque of the motor to be constant. Thus, force (pressure) applied between the insertion hole21B which is formed in the main body21of the ultrasonic vibrator20and formed with the inclined surface having the diameter slightly reduced toward the depth direction, and an outer side surface of the second insertion portion73B of the insertion portion73of the tool holder70is set constant, with the result that adhesion force therebetween is set constant. Accordingly, transmission of ultrasonic vibration from the ultrasonic vibrator20to the tool holder70can be kept stable all the time. Furthermore, since the male screw portion73C of the insertion portion73of the tool holder70and the female screw portion21C of the insertion hole21B formed in the horn portion21A of the ultrasonic vibrator20are tightened with a constant torque all the time, the life of these portions can be prolonged. Furthermore, tool replacement can be performed in a shorter time than manual tool replacement.

As described above, the ultrasonic vibration processing device according to the first embodiment includes the housing10, the ultrasonic vibrator20, the connecting portion30, the motor40, and the non-contact power supply unit50. The ultrasonic vibrator20includes the horn portion21A and the piezoelectric elements23. The horn portion21A has the distal end to which the tool holder70is detachably attached. The piezoelectric elements23are held at an intermediate portion of the ultrasonic vibrator20in the rotation axis X direction. The ultrasonic vibrator20has the rear end located at the node F1of ultrasonic vibration generated by the piezoelectric elements23. Furthermore, the ultrasonic vibrator20is supported inside the housing10so as to be rotatable around the rotation axis X. The connecting portion30has the front end portion connected to the rear end portion of the ultrasonic vibrator20. The connecting portion30is stored in the housing10so as to be rotatable around the rotation axis X together with the ultrasonic vibrator20. Furthermore, the connecting portion30includes the spline bearing31having the insertion opening opened at the rear end of the connecting portion30. The motor40includes the spline shaft45that is inserted into the spline bearing31through the insertion opening of the connecting portion30and rotatable around the rotation axis X, and the motor40is connected to the rear end portion of the connecting portion30. The non-contact power supply unit50includes the primary transformer51and the secondary transformer52. The primary transformer51is fixed to the housing10. The primary transformer51includes the primary coil51B that receives high frequency power from an external power supply. The secondary transformer52is connected to the rear end of the ultrasonic vibrator20with the clearance S maintained between the secondary transformer52and the primary transformer51. The secondary transformer52is rotated around the rotation axis X together with the ultrasonic vibrator20. Furthermore, the secondary transformer52includes the secondary coil52B that supplies an induced electromotive force generated between the secondary coil52B and the primary coil51B by electromagnetic induction, to the piezoelectric elements23.

In the ultrasonic vibration processing device, the rear end of the ultrasonic vibrator20is located at the node F1of ultrasonic vibration generated by the piezoelectric elements23, and the secondary transformer52is connected to the rear end of the ultrasonic vibrator20. Since no amplitude in the rotation axis X direction is exhibited at each of the nodes F0to F4and the like of the ultrasonic vibration, the secondary transformer52of the ultrasonic vibration processing device is less likely to receive vibration in the rotation axis X direction. Accordingly, the clearance S between the primary transformer51and the secondary transformer52of the ultrasonic vibration processing device does not easily change. Therefore, the non-contact power supply unit50of the ultrasonic vibration processing device can supply high frequency power to the piezoelectric element23in a stable manner.

Furthermore, in the ultrasonic vibration processing device, the connecting portion30and the motor40are connected by the spline bearing31and the spline shaft45. Therefore, although the connecting portion30is vibrated in the rotation axis X direction by the ultrasonic vibrator20, this vibration is not easily transmitted to the motor40. Accordingly, the motor40of the ultrasonic vibration processing device is not easily damaged by the vibration of the ultrasonic vibrator20, and the motor40can rotate in a preferable manner for a long time. Furthermore, friction of the connecting portion30can be reduced and abrasion thereof can be suppressed, so that a downtime required for attending to the friction and abrasion can be shortened. Furthermore, in the ultrasonic vibration processing device, ultrasonic vibration is not transmitted to the motor40, with the result that ultrasonic vibration energy generated by the piezoelectric elements23can be effectively transmitted to the tool.

Accordingly, the ultrasonic vibration processing device of the first embodiment can suppress vibration of the non-contact power supply unit50and the motor40which are components thereof due to the ultrasonic vibrator20, and can perform processing using ultrasonic vibration in a preferable manner.

Furthermore, the spline bearing31of the ultrasonic vibration processing device is located at the node F0of ultrasonic vibration generated by the piezoelectric elements23. Since no amplitude in the rotation axis X direction is exhibited at each of the nodes F0to F4and others of the ultrasonic vibration, vibration of the spline bearing31in the rotation axis X direction is small. Accordingly, the vibration is not easily transmitted to the motor40connected to the spline bearing31via the spline shaft45. Therefore, the ultrasonic vibration processing device can prevent damage to the motor40due to vibration of the ultrasonic vibrator20(e.g., damage of the bearing portion of the drive shaft43), so that the motor40can rotate in a preferable manner for a long time.

Furthermore, in the ultrasonic vibration processing device, the inner circumferential surface of the spline bearing31and the outer circumferential surface of the spline shaft45are coated with DLC. Therefore, friction between the spline bearing31and the spline shaft45of the ultrasonic vibration processing device is reduced, and abrasion resistance between the spline bearing31and the spline shaft45improves. Accordingly, the ultrasonic vibrator20and others of the ultrasonic vibration processing device can be rotated in a preferable manner for a long time.

Furthermore, the ultrasonic vibration processing device includes the reflecting member60that is held between the rear end of the ultrasonic vibrator20and the secondary transformer52and has a specific acoustic impedance different from that of the tightening portion27and others of the ultrasonic vibrator20. Therefore, in the ultrasonic vibration processing device, vibration is reflected toward the ultrasonic vibrator20by the reflecting member60held between the ultrasonic vibrator20and the secondary transformer52, and is not easily transmitted to the secondary transformer52. Accordingly, the secondary transformer52of the ultrasonic vibration processing device is less likely to receive vibration in the rotation axis X direction, so that the non-contact power supply unit50can supply high frequency power to the piezoelectric elements23in a stable manner.

Furthermore, in the ultrasonic vibration processing device, a specific acoustic impedance of the joint portion33of the connecting portion30and a specific acoustic impedance of the tightening portion27and others of the ultrasonic vibrator20are different from each other. Accordingly, a part of vibration generated by the ultrasonic vibrator20is reflected on the boundary between the joint portion33of the connecting portion30and the tightening portion27of the ultrasonic vibrator20, so that the vibration is not easily transmitted toward the connecting portion30. Accordingly, in the ultrasonic vibration processing device, vibration is not easily transmitted to the motor40so that damage due to the vibration is prevented, with the result that the motor40can rotate in a preferable manner for a long time.

The present invention is not limited to the first embodiment described above and depicted in the drawings. For example, following embodiments are also included in the technical scope of the present invention.

(1) In the first embodiment, the spline bearing is located at the node of the ultrasonic vibration generated by the piezoelectric elements. However, the spline bearing may not be located at the node.

(2) In the first embodiment, the inner circumferential surface of the spline bearing and the outer circumferential surface of the spline shaft are coated with DLC. However, other surface hardening treatment may be performed. Furthermore, surface hardening treatment may not be performed on the inner circumferential surface of the spline bearing and the outer circumferential surface of the spline shaft.

(3) In the first embodiment, the connecting portion and the drive shaft of the motor are connected by inserting the spline shaft formed at the distal end portion of the drive shaft into the spline bearing of the connecting portion. However, the connecting portion may include a cross-shaped recess like a head portion of a Phillips screw, and the drive shaft of the motor may include a distal end portion formed into a shape like a tip of a Phillips screwdriver, so that the distal end portion may be inserted into the recess to connect the connecting portion and the drive shaft of the motor.

(4) In the first embodiment, the reflecting member is held between the rear end of the ultrasonic vibrator and the secondary transformer. However, the reflecting member may not be held therebetween.

(5) In the first embodiment, the joint portion of the connecting portion is made of a titanium alloy. However, the joint portion may be made of an aluminum alloy. The aluminum alloy has a specific acoustic impedance different from that of stainless steel forming the tightening portion and others of the ultrasonic vibrator. Accordingly, a part of vibration generated by the ultrasonic vibrator is reflected on the boundary between the joint portion of the connecting portion and the tightening portion of the ultrasonic vibrator, so that the vibration is not easily transmitted toward the connecting portion.

(6) In the first embodiment, the tool holder is a shrink fit holder which shrink-fits the tool to the chuck portion. However, the tool holder may be a collet chuck.

(7) in the first embodiment, the end mill is attached to the tool holder. However, other cutting/grinding tools may be attached.

REFERENCE SIGNS LIST

50non-contact power supply unit

51B primary coil

X rotation axis