Medical cutting instruments and cartridges

Abstract

To provide a medical cutting instrument capable of preventing a turbine rotor and a spindle from falling off by increasing fixing force of a joint part for fixing the spindle and the turbine rotor using a material with a large moment of inertia such as stainless steel, and a cartridge to be detachably attached to the medical cutting instrument.SOLUTION: A medical cutting instrument comprises a rotating part including a turbine rotor and a spindle. The turbine rotor is formed of a metal having a bulk density of 4.0 (g / cm3) or more and a value of Young modulus (GPa) / bulk density (g / cm3) of 20 or more. The spindle has a hollow substantially-cylindrical shape, where a cutting tool can be inserted in the hollow inside. The rotating part includes a joint part to which an inner peripheral surface of the turbine rotor and an outer peripheral surface of the spindle are fixed with an adhesive, and the joint part includes a groove in at least one of the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a medical cutting instrument used in dentistry or surgery, and to a cartridge that is detachably attached to the medical cutting instrument. [Background technology]

[0002] Medical cutting instruments such as air turbine handpieces have been known for some time. For example, in dental practice, various medical cutting instruments are used, such as air turbine handpieces with cutting tools such as diamond point burrs, carbide burrs, files, and reamers attached to the head, and micromotor handpieces. For example, Patent Document 1 describes an air turbine handpiece, which is a medical cutting instrument.

[0003] The air turbine handpiece described in Patent Document 1 has a head portion housing a turbine rotor and a spindle. The spindle has a hollow, approximately cylindrical shape and is axially supported by the head portion via a bearing. The turbine rotor is fixed to the outer circumferential surface of the spindle, and a cutting tool is inserted into the hollow interior of the spindle.

[0004] In this type of air turbine handpiece, the turbine rotor has generally been made of aluminum from the viewpoint of ease of processing during molding.

[0005] On the other hand, in the dental air turbine described in Patent Document 2, the rotating part (turbine rotor) is made of stainless steel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-174901 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-000311 Summary of the Invention [Problem to be solved by the invention]

[0007] However, turbine rotors made of such stainless steel have a large moment of inertia, which means that when a cutting load is applied, a large load is placed on the joint that secures the turbine rotor to the spindle, which can lead to problems such as heat generation and difficulty in attaching and detaching the cutting tool.

[0008] Furthermore, a turbine rotor made of a material with a large moment of inertia has the drawback that it takes a long time for the rotor to stop rotating due to inertia when the supply of high-pressure air is stopped.

[0009] The present invention provides a medical cutting instrument and a cartridge that can be detachably attached to the medical cutting instrument, which can increase the adhesive strength of the joint that secures the turbine rotor, which is made of a material with a large moment of inertia such as stainless steel, to the spindle, and prevent the turbine rotor from coming off the spindle. [Means for solving the problem]

[0010] A first aspect of the present invention is A medical cutting instrument comprising a rotating part having a turbine rotor and a spindle, The turbine rotor has a density of 4.0 [g / cm 3 ] or more, Young's modulus [GPa] / density [g / cm 3 ] is made of metals with a value of 20 or more, the spindle has a hollow, generally cylindrical shape, its outer circumferential surface is rotatably supported by a bearing, and its inner circumferential surface is provided with a chuck mechanism, and a cutting tool can be inserted into the hollow interior; The rotating part is a joint portion where an inner peripheral surface of the turbine rotor and an outer peripheral surface of the spindle are fixed with an adhesive; The joint is The medical cutting instrument has a groove on at least one of the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle.

[0011] A second aspect of the present invention is A medical cutting instrument comprising a rotating part having a turbine rotor and a spindle, the spindle has a hollow, generally cylindrical shape, its outer circumferential surface is rotatably supported by a bearing, and its inner circumferential surface is provided with a chuck mechanism, and a cutting tool can be inserted into the hollow interior; The rotating part is The inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle are fixed together with an adhesive. having a department, The joint is a medical cutting instrument having grooves on the inner peripheral surface of the turbine rotor and on the outer peripheral surface of the spindle; It is a machine. [Effects of the Invention]

[0012] According to the present invention, it is possible to increase the adhesive strength of the joint that fixes the turbine rotor and the spindle, which are made of a material with a large moment of inertia, such as stainless steel. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of a head portion of an air turbine handpiece having a rotating portion of the present invention. [Figure 2] 1 is a schematic diagram of a rotating part (cross section of a turbine rotor and side view of a spindle) according to the present invention. [Figure 3a] 1 is a cross-sectional view of a turbine rotor according to the present invention; [Figure 3b] 1 is a perspective view of a turbine rotor according to the present invention; [Figure 4a] FIG. 2 is a side view of the spindle of the present invention. [Figure 4b] FIG. 2 is a cross-sectional view of the spindle of the present invention. [Figure 5a] 1 is a schematic diagram of grooves intersecting at the joint of the rotating part of the present invention; FIG. [Figure 5b] FIG. 5b is an enlarged view of the vicinity of the groove in FIG. 5a. [Figure 6] 1 is a schematic diagram showing a cartridge housed in a head portion of an air turbine handpiece of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a medical cutting instrument and an air turbine handpiece as an example of a cartridge detachably attached to the medical cutting instrument according to the present invention will be described with reference to the accompanying drawings. The drawings should be viewed in the direction indicated by the reference numerals.

[0015] [First embodiment] First, an air turbine handpiece 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0016] 1, the air turbine handpiece 1 of this embodiment includes a handpiece body 10, which is the main body of the air turbine handpiece 1, and a head portion 20 provided at the distal end of the handpiece body 10. A cutting tool 30 is removably attached to the head portion 20. Multiple types of cutting tools 30 may be attached to the head portion 20 depending on the cutting target to be cut using the air turbine handpiece 1, etc.

[0017] A cylindrical shaft portion 31 is formed at one end of the cutting tool 30 attached to the head portion 20. The cutting tool 30 is attached to the head portion 20 by inserting the shaft portion 31 into the head portion 20. One end of the cutting tool 30 (i.e., the tip portion of the shaft portion 31) is housed in the head portion 20, and the other end of the cutting tool 30 protrudes from the head portion 20 to the outside.

[0018] For the sake of simplicity and clarity, the present specification and the like will define the X direction as the axial direction of the shaft 31 of the cutting tool 30 in the air turbine handpiece 1 in which the cutting tool 30 is attached to the head 20. One end of the cutting tool 30 (i.e., the tip of the shaft 31) will be defined as the X1 side, and the other end of the cutting tool 30 as the X2 side, for the sake of simplicity and clarity. Unless otherwise specified, the axial direction, circumferential direction, and radial direction refer to directions based on the axial direction of the shaft 31.

[0019] Therefore, a shaft portion 31 is formed at the X1 side end of the cutting tool 30. The X1 side end of the cutting tool 30 is housed in the head portion 20, and the X2 side end of the cutting tool 30 protrudes from the head portion 20 in the X2 direction.

[0020] The head unit 20 includes a main housing 21 having a generally cylindrical shape with a bottom that is open on the X1 side, and a head cap 22 that closes the opening that opens on the X1 side of the main housing 21. In the head unit 20, an internal storage space 200 that is surrounded by the main housing 21 and the head cap 22 is formed.

[0021] The internal storage space 200 of the head unit 20 accommodates a cartridge 40, which is a modularized combination of a spindle 41 having a hollow, generally cylindrical shape extending in the X direction, a turbine rotor 42 fixed to the outer circumferential surface of the spindle 41 with an adhesive, a chuck mechanism 44 supported on the inner circumferential surface of the spindle 41, a first bearing 451, a second bearing 452, and seal members 511 and 512. In this embodiment, the cartridge 40 is detachable from the head unit 20 (see FIG. 6). Therefore, by replacing the cartridge 40 attached to the head unit 20, the spindle 41, the turbine rotor 42, the chuck mechanism 44, the first bearing 451, the second bearing 452, and the seal members 511 and 512 can be replaced. Furthermore, multiple types of cartridges 40 may be attached to the head unit 20 depending on the cutting target to be cut using the air turbine handpiece 1.

[0022] The head cap 22 has a substantially annular outer member 221 that is fitted into and fixed to the main housing 21, and a substantially annular inner member 222 that is fixed to the inner circumferential surface of the outer member 221. A push button 23 that is displaceable in the X direction relative to the main housing 21 and the head cap 22 is provided on the X1 side of the head cap 22. The push button 23 is connected to a chuck mechanism 44 of the cartridge 40. A coil spring 24 is attached between the push button 23 and the head cap 22, and the push button 23 is biased by the coil spring 24 toward the X1 side relative to the head cap 22.

[0023] The X1 side end of the spindle 41 is rotatably supported by a first bearing 451. The X2 side end of the spindle 41 is rotatably supported by a second bearing 452. The first bearing 451 is fixed to the inner circumferential surface of the inner member 222 of the head cap 22 via an O-ring 491, and the second bearing 452 is fixed to the inner circumferential surface of the main housing 21 via an O-ring 492.

[0024] The turbine rotor 42 has a substantially cylindrical rotating shaft portion 421 that fits onto the outer peripheral surface of the spindle 41, and a plurality of turbine blade portions 422 that extend radially outward relative to the axial direction of the rotating shaft portion 421 and have a blade shape. The rotating shaft portion 421 and the turbine blade portions 422 may be integrally molded from the same material, or may be formed from different materials and integrated by bonding. In this embodiment, the rotating shaft portion 421 and the turbine blade portions 422 are integrally molded from the same material. When the turbine rotor 42 rotates, the spindle 41 also rotates integrally with the turbine rotor 42.

[0025] The chuck mechanism 44 has a hollow, generally cylindrical shape and includes a chuck 441 fitted to and supported by the inner circumferential surface of the spindle 41, and a pusher 442 provided at the X1 side end of the spindle 41 for operating the chuck 441. The cutting tool 30 is supported by the chuck 441 so as not to be displaced radially relative to the spindle 41.

[0026] The pusher 442 is fitted to the inner peripheral surface of the spindle 41 and supported so as to be slidable in the X direction. The pusher 442 operates the chuck portion 441 to switch between a state in which the X1 side end of the shaft portion 31 of the cutting tool 30 is held by the chuck portion 441 and a state in which it is not held by the chuck portion 441.

[0027] When the user presses the push button 23 toward the X2 side, the pusher 442 connected to the push button 23 slides toward the X2 side. The chuck portion 441 can be switched between an open state and a closed state and is normally in the closed state. When the user presses the push button 23 toward the X2 side, the chuck mechanism portion 44 opens the chuck portion 441, causing the pusher 442 to slide toward the X2 side.

[0028] When attaching the cutting tool 30 to the head unit 20, the user presses the push button 23 toward the X2 side, causing the pusher 442 to slide toward the X2 side and maintaining the chuck unit 441 in an open state, ready to accept the cutting tool 30. Then, with the chuck unit 441 maintained in the open state, the shaft unit 31 of the cutting tool 30 is inserted into the hollow interior of the spindle 41 from the X2 side, and the tip of the shaft unit 31 of the cutting tool 30 abuts against the chuck mechanism unit 44. Then, when the user releases the push button 23 with the tip of the shaft unit 31 of the cutting tool 30 abutting against the chuck mechanism unit 44, the pusher 442 slides toward the X1 side and the chuck unit 441 becomes a closed state while holding the shaft unit 31 of the cutting tool 30. The cutting tool 30 is maintained held by the chuck mechanism unit 44 and is attached to the head unit 20 via the cartridge 40. This allows the cutting tool 30 to rotate integrally with the spindle 41 and the turbine rotor 42.

[0029] When removing the cutting tool 30 from the head unit 20, the user presses the push button 23 toward the X2 side while the cutting tool 30 is held in the chuck unit 441, causing the pusher 442 to slide toward the X2 side, opening the chuck unit 441 and enabling removal of the cutting tool 30. Then, the user pulls out the cutting tool 30 toward the X2 side while pressing the push button 23 toward the X2 side, whereby the cutting tool 30 is released from the chuck mechanism unit 44 and removed from the head unit 20.

[0030] The handpiece body 10 includes a supply duct (not shown) that supplies high-pressure air (compressed air), which is the working gas for the turbine rotor 42, to the head unit 20, and a discharge duct (not shown) that discharges the high-pressure air supplied to the head unit 20 to the outside. The high-pressure air supplied to the head unit 20 is discharged to the outside not only from the discharge duct but also from gaps formed between the outer peripheral surface of the spindle 41 and contact pieces 511b and 512b of sealing members 511 and 512, which will be described later.

[0031] High-pressure air supplied from the supply duct is supplied to the cartridge 40 and sprayed onto the turbine blade portion 422 of the turbine rotor 42. When the turbine blade portion 422 of the turbine rotor 42 receives the high-pressure air, the turbine rotor 42 rotates. As a result, the spindle 41 and the cutting tool 30 rotate integrally with the turbine rotor 42.

[0032] The turbine rotor 42 is made of a metal with a density of 4.0 g / cm3 or greater and a Young's modulus (GPa) / density (g / cm3) ratio of 20 or greater. If the turbine rotor 42 has a diameter of 10 mm, an axial length of 3.2 mm, and eight blades, the moment of inertia of the turbine rotor 42 is 10.8 g·mm2 if it is made of stainless steel. For reference, if a turbine rotor of the same shape is made of aluminum, the moment of inertia of the turbine rotor is 3.7 g·mm2.

[0033] In this way, by forming the turbine rotor 42 from a metal having a density of 4.0 [g / cm3] or more, it is possible to increase the moment of inertia of the turbine rotor 42. This makes it possible to reduce a sudden increase in the rotational speed of the turbine rotor 42 when high-pressure air starts to be supplied from the supply duct of the handpiece body 10 to the head unit 20, thereby reducing the load on the first bearing 451 and the second bearing 452. Furthermore, when a cutting load is input to the turbine rotor 42 via the cutting tool 30 during rotation of the turbine rotor 42, it is possible to prevent the turbine rotor 42 from stalling and the cutting force of the cutting tool 30 from decreasing.

[0034] Furthermore, the turbine rotor 42 has a Young's modulus [GPa] / density [g / cm3] value of 20 or greater. Generally, when the same force is applied to objects of the same shape but different Young's moduli, the larger the Young's modulus, the less deformation there will be. Furthermore, when objects of the same shape but different densities are subjected to the same rotation, the larger the density, the greater the force acting on the object. Therefore, the larger the Young's modulus and the lower the density, the less deformation there will be due to rotation. In this embodiment, the turbine rotor 42 has a Young's modulus [GPa] / density [g / cm3] value of 20 or greater, so that the amount of deformation of the turbine rotor 42 can be reduced even when the turbine rotor 42 rotates at high speed. Therefore, even when the turbine rotor 42 rotates at high speed, the inner diameter of the rotating shaft portion 421 can be prevented from expanding, and the fixation between the turbine rotor 42 and the spindle 41 can be prevented from loosening.

[0035] Furthermore, in the air turbine handpiece 1, the center of gravity can be positioned closer to the head portion 20, which increases the natural frequency of the turbine rotor 42 when high-pressure air is supplied from the supply duct of the handpiece body 10 to the head portion 20 and the turbine rotor 42 is rotating. This reduces unpleasant noise generated by the turbine rotor 42 when high-pressure air is supplied from the supply duct of the handpiece body 10 to the head portion 20 and the turbine rotor 42 is rotating.

[0036] In this embodiment, the turbine rotor 42 is made of stainless steel. More specifically, in this embodiment, the turbine rotor 42 is made of SUS303, which is an austenitic stainless steel.

[0037] In this way, the turbine rotor 42 is formed from stainless steel, which is an easily processed material, and therefore the turbine rotor 42 can be easily molded.

[0038] Furthermore, the turbine rotor 42 is made of austenitic stainless steel, a material that is resistant to corrosion even when washed with hot water, and therefore has excellent corrosion resistance. This eliminates the need for surface treatment of the turbine rotor 42 to improve corrosion resistance, such as coating it with anodized aluminum.

[0039] The turbine rotor 42 is made of a metal with a density of 4.0 g / cm3 or greater and a Young's modulus (GPa) / density (g / cm3) ratio of 20 or greater. Compared to conventional aluminum, this metal has a larger moment of inertia, resulting in a larger inertial force during rotation of the turbine rotor 42. Therefore, when a cutting load is applied, the spindle 42 is stopped via the cutting tool 30, and a load in the opposite direction to the rotational direction is generated at the joint 46 of the rotating part 4. If the adhesive strength between the turbine rotor 42 and the spindle 41 at the joint 46 weakens, the spindle 41 may easily move axially when an axial load acts, causing a cutting load to be applied. This could result in problems such as heat generation or difficulty in attaching or detaching the cutting tool.

[0040] As shown in Fig. 2, the rotating unit 4 made up of the turbine rotor 42 and the spindle 41 has a joint 46 where an outer peripheral surface 415 of the spindle 41 and an inner peripheral surface 425 of the turbine rotor 42 are fixed together with an adhesive. As shown in Fig. 3, grooves 426 parallel to the circumferential direction are formed at regular intervals in the axial direction on the inner peripheral surface 425 of the turbine rotor 42, and as shown in Fig. 4, a groove 416 which is a helical thread groove is formed on the outer peripheral surface 415 of the spindle 41. In this embodiment, the grooves are formed on both the inner peripheral surface 425 of the turbine rotor 42 and the outer peripheral surface 415 of the spindle 41, but it is sufficient if a groove is formed on at least one of them.

[0041] In this way, the joint 46 has the groove 426 on the inner circumferential surface 425 of the turbine rotor 42 and the groove 416 on the outer circumferential surface 415 of the spindle 41, and therefore the adhesive acts on the grooves 426, 416, resinifying them, thereby increasing the adhesive strength of the joint 46. This prevents the turbine rotor 42 from falling off the spindle 41.

[0042] In this embodiment, the groove 426 on the inner circumferential surface 425 of the turbine rotor 42 and the groove 416 on the outer circumferential surface 415 of the spindle 41 intersect with each other. There are no restrictions on the intersection of the groove 426 on the inner circumferential surface 425 of the turbine rotor 42 and the groove 416 on the outer circumferential surface 415 of the spindle 41. For example, the grooves 426 and 416 may be threaded in opposite directions, i.e., clockwise and counterclockwise, so that they intersect with each other. This allows the adhesive resinified at the portion of the joint 46 where the groove 426 and the groove 416 intersect to act as a wedge, further increasing the fixing strength of the joint 46 and preventing the turbine rotor 42 from coming off the spindle 41.

[0043] As shown in FIG. 5 , at the joint 46 of the rotating part 4, a groove 426 parallel to the circumferential direction on the inner circumferential surface 425 of the turbine rotor 42 and a groove 416, which is a spiral thread groove, on the outer circumferential surface 415 of the spindle 41 intersect with each other. Because the groove 426 on the inner circumferential surface 425 of the turbine rotor 42 is parallel to the circumferential direction, when an excessive load acts in the circumferential direction during rotation, the adhesive bonded to the groove 426 in the outer circumferential direction is preferentially released, preventing detachment of the adhesive bonded to the resin throughout the joint 46. Release of the adhesive bond in the outer circumferential direction of the groove 426 prevents detachment of the turbine rotor 42 and the spindle 41 in the axial direction. In this embodiment, the groove 426 on the inner circumferential surface 425 of the turbine rotor 42 is parallel to the circumferential direction. However, the present invention is not limited to this. The groove 416 on the outer circumferential surface 415 of the spindle 41 may also be parallel to the circumferential direction.

[0044] The adhesive used in this embodiment is an acrylic pressure-sensitive adhesive, preferably an acrylic resin-based anaerobic adhesive, and more preferably Loctite (registered trademark) 648.

[0045] The first bearing 451 has an inner ring 451a and an outer ring 451b facing each other, and a ball 451c located in the gap between the inner ring 451a and the outer ring 451b.

[0046] At the X1 side end of the outer ring 451b of the first bearing 451, a clamping portion 451d is formed which extends radially inward and supports the seal member 511 from the X2 side.

[0047] An extension portion 451e that extends radially outward and supports the O-ring 491 from the X2 side is formed at the X2 side end of the outer ring 451b of the first bearing 451.

[0048] An inner ring opening 451a1 is formed on the inner side of the inner ring 451a of the first bearing 451. This inner ring opening 451a1 is fixed to the outer peripheral surface of the spindle 41. Therefore, the inner ring 451a rotates together with the spindle 41.

[0049] A seal holding member 521 is attached to the X1 side of the outer ring 451b of the first bearing 451. The seal holding member 521 is engaged with the outer peripheral surface of the outer ring 451b of the first bearing 451. The seal holding member 521 is formed with a base portion 521a that faces the X1 side surface of the outer ring 451b of the first bearing 451, a clamping portion 521b that extends from the base portion 521a to the X1 side and supports the seal member 511 from the X1 side, and a locking portion 521c that extends from the base portion 521a to the X2 side, supports the O-ring 491 from the X1 side, and is engaged with the outer peripheral surface of the outer ring 451b of the first bearing 451.

[0050] The seal member 511 is made of an elastic material. The seal member 511 is made of, for example, silicone rubber or fluororubber. The seal member 511 may be made of an elastic material other than silicone rubber or fluororubber. The seal member 511 has a ring shape that surrounds the outer peripheral surface of the spindle 41 and is open at the center. The seal member 511 includes an outer peripheral portion 511a that is the thickest, and a contact piece 511b that extends from the inner edge of the outer peripheral portion 511a toward the center of the ring. The contact piece 511b has a lower elastic modulus than the outer peripheral portion 511a and is therefore more susceptible to elastic deformation. In the seal member 511, a ring opening 511c is formed in the center of the ring, further from the contact piece 511b.

[0051] The outer circumferential portion 511a of the seal member 511 is supported on the X1 side by the clamping portion 521b of the seal holding member 521 and on the X2 side by the clamping portion 451d of the first bearing 451, and is clamped between the clamping portion 521b of the seal holding member 521 and the clamping portion 451d of the first bearing 451.

[0052] The contact piece 511b of the seal member 511 is disposed in a space surrounded by the inner peripheral surface of the clamping portion 521b of the seal holding member 521 and the outer peripheral surface of the spindle 41. When the turbine rotor 42 of the air turbine handpiece 1 is not operating, that is, when high-pressure air is not being supplied to the head unit 20 from the supply duct of the handpiece body 10, the contact piece 511b is in contact with the outer peripheral surface of the spindle 41.

[0053] The diameter of the ring opening 511c of the seal member 511 is smaller than the diameter of the outer circumferential surface of the spindle 41. Therefore, when the turbine rotor 42 of the air turbine handpiece 1 is not operating, that is, when high-pressure air is not being supplied to the head portion 20 from the supply duct of the handpiece body 10, the contact piece 511b of the seal member 511 is bent toward the X1 side and comes into contact with the outer circumferential surface of the spindle 41 due to contact pressure caused by elastic force. The position where the contact piece 511b comes into contact with the outer circumferential surface of the spindle 41 is the opening edge of the ring opening 511c.

[0054] In this way, when high-pressure air is not supplied from the supply duct of the handpiece body 10 to the head portion 20 and the turbine rotor 42 is not rotating, the contact piece 511b of the sealing member 511 abuts against the outer peripheral surface of the spindle 41, blocking (sealing) the gap between the head cap 22 and the spindle 41.

[0055] This makes it possible to prevent foreign matter such as saliva or blood from entering the inside of the cartridge 40.

[0056] The second bearing 452 has an inner ring 452a and an outer ring 452b facing each other, and a ball 452c located in a gap between the inner ring 452a and the outer ring 452b.

[0057] At the X2 side end of the outer ring 452b of the second bearing 452, a clamping portion 452d is formed which extends radially inward and supports the seal member 512 from the X1 side.

[0058] An extension portion 452e that extends radially outward and supports the O-ring 492 from the X1 side is formed at the X1 side end of the outer ring 452b of the second bearing 452.

[0059] An inner ring opening 452a1 is formed on the inner side of the inner ring 452a of the second bearing 452. This inner ring opening 452a1 is fixed to the outer peripheral surface of the spindle 41. Therefore, the inner ring 452a rotates together with the spindle 41.

[0060] A seal holding member 522 is attached to the X2 side of the outer ring 452b of the second bearing 452. The seal holding member 522 is engaged with the outer peripheral surface of the outer ring 452b of the second bearing 452. The seal holding member 522 is formed with a base portion 522a that faces the X2 side surface of the outer ring 452b of the second bearing 452, a clamping portion 522b that extends from the base portion 522a toward the X2 side and supports the seal member 512 from the X2 side, and a locking portion 522c that extends from the base portion 522a toward the X1 side, supports the O-ring 492 from the X2 side, and is engaged with the outer peripheral surface of the outer ring 452b of the second bearing 452.

[0061] The seal member 512 is made of an elastic material. The seal member 512 is made of, for example, silicone rubber or fluororubber. The seal member 512 may be made of an elastic material other than silicone rubber or fluororubber. The seal member 512 has a ring shape that surrounds the outer peripheral surface of the spindle 41 and is open at the center. The seal member 512 includes an outer peripheral portion 512a that is the thickest, and a contact piece 512b that extends from the inner edge of the outer peripheral portion 512a toward the center of the ring. The contact piece 512b has a lower elastic modulus than the outer peripheral portion 512a and is therefore more susceptible to elastic deformation. In the seal member 512, a ring opening 512c is formed in the center of the ring, further from the contact piece 512b.

[0062] The outer periphery 512a of the seal member 512 is supported on the X1 side by the clamping portion 452d of the second bearing 452 and on the X2 side by the clamping portion 522b of the seal holding member 522, and is clamped between the clamping portion 452d of the second bearing 452 and the clamping portion 522b of the seal holding member 522.

[0063] The contact piece 512b of the seal member 512 is disposed in a space surrounded by the inner peripheral surface of the clamping portion 522b of the seal holding member 522 and the outer peripheral surface of the spindle 41. When the turbine rotor 42 of the air turbine handpiece 1 is not operating, that is, when high-pressure air is not being supplied to the head portion 20 from the supply duct of the handpiece body 10, the contact piece 512b is in contact with the outer peripheral surface of the spindle 41.

[0064] The diameter of the ring opening 512c of the seal member 512 is smaller than the diameter of the outer peripheral surface of the spindle 41. Therefore, when the turbine rotor 42 of the air turbine handpiece 1 is not operating, that is, when high-pressure air is not being supplied to the head portion 20 from the supply duct of the handpiece body 10, the contact piece 512b of the seal member 512 is bent toward the X2 side and comes into contact with the outer peripheral surface of the spindle 41 due to contact pressure caused by elastic force. The position where the contact piece 512b comes into contact with the outer peripheral surface of the spindle 41 is the opening edge of the ring opening 512c.

[0065] In this way, when high-pressure air is not supplied from the supply duct of the handpiece body 10 to the head portion 20 and the turbine rotor 42 is not rotating, the contact piece 512b of the sealing member 512 abuts against the outer peripheral surface of the spindle 41, blocking (sealing) the gap between the main housing 21 and the spindle 41.

[0066] This makes it possible to prevent foreign matter such as saliva or blood from entering the inside of the cartridge 40.

[0067] When high-pressure air is supplied to the head portion 20 from the supply duct of the handpiece body 10, the air pressure in the internal accommodating space 200 increases, and when the turbine rotor 42 rotates at a predetermined speed or higher, air leaks from the internal accommodating space 200 through the first bearing 451 into the space where the contact piece 511b of the sealing member 511 is located, and then through the second bearing 452 into the space where the contact piece 512b of the sealing member 512 is located.

[0068] As a result, the contact piece 511b of the sealing member 511 is pushed outward radially from the spindle 41 by the air leaking into the space in which the contact piece 511b of the sealing member 511 is located, and the contact piece 511b of the sealing member 511 separates from the outer peripheral surface of the spindle 41, creating a gap between the contact piece 511b of the sealing member 511 and the outer peripheral surface of the spindle 41.

[0069] Similarly, the contact piece 512b of the sealing member 512 is pushed outward radially from the spindle 41 by the air leaking into the space in which the contact piece 512b of the sealing member 512 is located, causing the contact piece 512b of the sealing member 512 to separate from the outer peripheral surface of the spindle 41, creating a gap between the contact piece 512b of the sealing member 512 and the outer peripheral surface of the spindle 41.

[0070] As described above, when high-pressure air is supplied to the head portion 20 from the supply duct of the handpiece body 10, the turbine blade portion 422 of the turbine rotor 42 receives the high-pressure air, causing the turbine rotor 42 to rotate, and the spindle 41 and cutting tool 30 to rotate integrally with the turbine rotor 42. When high-pressure air is supplied to the head portion 20 from the supply duct of the handpiece body 10, gaps are generated between the contact piece 511b of the seal member 511 and the outer peripheral surface of the spindle 41, and between the contact piece 512b of the seal member 512 and the outer peripheral surface of the spindle 41. This means that the spindle 41 rotates easily without contact resistance between the contact piece 511b of the seal member 511 and the contact piece 512b of the seal member 512.

[0071] On the other hand, when high-pressure air is supplied from the supply duct of the handpiece body 10 to the head portion 20, causing the turbine rotor 42, spindle 41, and cutting tool 30 to rotate together, if the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped, the rotational speed of the turbine rotor 42, spindle 41, and cutting tool 30 slows down and the amount of air leaking into the space in which the contact piece 511b of the seal member 511 and the space in which the contact piece 512b of the seal member 512 are located decreases, and when the rotational speed of the turbine rotor 42 drops below a predetermined speed, the contact piece 511b of the seal member 511 and the contact piece 512b of the seal member 512, which had been pushed radially outward from the spindle 41, return to a state in which they are in contact with the outer peripheral surface of the spindle 41. The rotation of the turbine rotor 42, spindle 41, and cutting tool 30 is braked by the contact resistance between the contact piece 511b of the seal member 511 and the outer peripheral surface of the spindle 41 and the contact resistance between the contact piece 512b of the seal member 512 and the outer peripheral surface of the spindle 41. In this way, the seal members 511 and 512 also function as a quick stop mechanism that brakes the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 when the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped. As a result, the seal members 511 and 512 can stop the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 in a short time after the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped.

[0072] Furthermore, the air turbine handpiece 1 is provided with sealing members 511 and 512 that also function as a quick-stop mechanism that brakes the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 when the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped. Therefore, even if a material with a large moment of inertia is used for the turbine rotor 42, the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 can be stopped in a short time after the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped.

[0073] In this embodiment, sealing members 511 and 512 are provided on both the X1 side of the first bearing 451 and the X2 side of the second bearing 452. Therefore, even if a material with a large moment of inertia is used for the turbine rotor 42, it is possible to increase the braking force that brakes the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 when the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped.

[0074] Furthermore, since the seal members 511 and 512 function as a quick stop mechanism that brakes the rotation of the turbine rotor 42, the spindle 41, and the cutting tool 30, the quick stop mechanism can be provided without increasing the number of parts.

[0075] Furthermore, before use, the air turbine handpiece 1 is injected with a lubricant into the head unit 20. Therefore, the air turbine handpiece 1 is used with a lubricant coating on each internal part of the head unit 20. For example, first, a sufficient amount of lubricant is injected into the head unit 20 from the supply duct of the handpiece body 10 to remove dirt adhering to each internal part of the head unit 20 and to create a lubricant coating on each internal part of the head unit 20. Thereafter, excess lubricant is removed before using the air turbine handpiece 1.

[0076] This prevents defects in the components inside the head unit 20 due to the adhesion of dirt, and also prevents wear on the first bearing 451 and the second bearing 452. Furthermore, since the outer peripheral surface 415 of the spindle 41 and the seal members 511 and 512 are also coated with lubricant when the air turbine handpiece 1 is in use, the supply of high-pressure air from the supply duct of the handpiece body 10 to the head unit 20 is stopped from a state in which the turbine rotor 42, spindle 41, and cutting tool 30 are rotating together, and the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 is braked due to contact resistance between the contact pieces 511b and 512b of the seal members 511 and 512 and the outer peripheral surface of the spindle 41.

[0077] As described above, the quick-stop mechanism made of sealing members is provided, so that the long-term inertial rotation that occurs when a material with a large moment of inertia is used for the turbine rotor can be stopped in a short time. On the other hand, when sealing members 511, 512 of the quick-stop mechanism come into contact with the outer circumferential surface of spindle 41, a sudden brake is applied, and additional load is applied to joint 46 of rotating part 4. However, grooves 426 and / or grooves 416 provide increased adhesive strength to joint 46, so that separation of turbine rotor 42 and spindle 41 can be prevented.

[0078] [Second embodiment] Next, a second embodiment of the present invention will be described. In the following description, the same components as those in the air turbine handpiece 1 of the first embodiment will be denoted by the same reference numerals, and their description will be omitted or simplified. Differences from the air turbine handpiece 1 of the first embodiment will be described in detail below.

[0079] The second embodiment differs from the first embodiment in that the material of the turbine rotor 42 of the air turbine handpiece 1 is not limited.

[0080] As a result, even if the material of the turbine rotor 42 is conventional aluminum, the adhesive acts on the grooves 426 on the inner surface 425 of the turbine rotor 42 and the grooves 416 on the outer surface 415 of the spindle 41, turning them into resin, thereby increasing the adhesive strength of the joint 46.

[0081] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner without departing from the spirit of the invention.

[0082] For example, in the turbine rotor 42 of the first embodiment, a metal such as titanium may be used instead of stainless steel.

[0083] Furthermore, for example, in the first and second embodiments, a plurality of sealing members 511, 512 may be provided on the X1 side of the first bearing 451 and / or a plurality of sealing members 511, 512 may be provided on the X2 side of the second bearing 452. By increasing the number of sealing members 511 and 512, even if a material with a large moment of inertia is used for the turbine rotor 42, it is possible to further increase the braking force that brakes the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 when the supply of high-pressure air from the supply duct of the handpiece body 10 to the head unit 20 is stopped.

[0084] Furthermore, for example, in the first and second embodiments, the spindle 41, the turbine rotor 42, the chuck mechanism 44, the first bearing 451 and the second bearing 452, and the sealing members 511 and 512 are modularized as a cartridge 40 that is detachable from the head portion 20, but the spindle 41, the turbine rotor 42, the chuck mechanism 44, the first bearing 451 and the second bearing 452, and the sealing members 511 and 512 do not have to be modularized.

[0085] Furthermore, for example, in the first and second embodiments, the sealing members 511, 512 are fixed to the seal holding members 521, 522 of the cartridge 40, but the sealing members 511, 512 may be provided on the first bearing 451 and / or the second bearing 452.

[0086] Furthermore, for example, in the first embodiment, the turbine rotor 42 is made of a material with a large moment of inertia, but the turbine rotor 42 may be provided with a pair of weights that are provided in the X direction on the X1-side surface and the X2-side surface of the turbine rotor 42. The weights are formed of a material that has a higher density than the material of the turbine rotor 42. Each of the pair of weights has a ring shape centered on the rotation axis of the turbine rotor 42, and is formed to fit onto the outer peripheral surface of the spindle 41, so that they can be attached later.

[0087] Furthermore, for example, in the first and second embodiments, grooves 426 parallel to the circumferential direction are formed at regular intervals in the axial direction on the inner surface 425 of the turbine rotor 42, and groove 416, which is a spiral screw groove, is formed on the outer surface 415 of the spindle 41, but there are no restrictions on the shape, size, angle, depth, spacing, etc. of grooves 426, 416, as long as the adhesive acts on grooves 426, 416 and resinifies them, thereby increasing the adhesive strength of joint 46.

[0088] This specification describes at least the following: In parentheses, components corresponding to those in the above-described embodiments are shown as examples, but the present invention is not limited to these.

[0089] (1) A medical cutting instrument (air turbine handpiece 1) having a rotating part (rotating part 4) including a turbine rotor (turbine rotor 42) and a spindle (spindle 41), the turbine rotor is formed of a metal having a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] ratio of 20 or more, The spindle has a hollow, generally cylindrical shape, and a cutting tool can be inserted into the hollow interior thereof. The rotating part is a joint (joint 46) at which an inner peripheral surface (inner peripheral surface 425) of the turbine rotor and an outer peripheral surface (outer peripheral surface 415) of the spindle are fixed together with an adhesive; The joint is A medical cutting instrument having grooves (grooves 416, 426) on at least one of the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle.

[0090] According to (1), the adhesive strength of the joint that secures the turbine rotor, which is made of a metal with a large moment of inertia, a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more, to the spindle can be increased, thereby preventing the turbine rotor from falling off the spindle.

[0091] (2) A medical cutting instrument according to (1), The joint is A medical cutting instrument having grooves on the inner peripheral surface of the turbine rotor and on the outer peripheral surface of the spindle.

[0092] According to (2), by providing grooves on both the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle at the joint, the adhesive strength of the joint can be further increased.

[0093] (3) A medical cutting instrument according to (2), The joint is A medical cutting instrument, wherein grooves on the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle intersect with each other.

[0094] According to (3), the grooves on the inner surface of the turbine rotor and the outer surface of the spindle at the joint intersect with each other, so that the resinified adhesive at the joint acts as a wedge at the intersecting point, further increasing the adhesive strength of the joint.

[0095] (4) A medical cutting instrument according to (3), The joint is A medical cutting instrument, wherein at least one of the grooves on the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle is parallel to the circumferential direction.

[0096] According to (4), when an excessive load acts in the circumferential direction during rotation, the adhesion in the outer circumferential direction of the groove is released, preventing the resinified adhesive from coming off throughout the joint. By releasing the adhesion in the outer circumferential direction of the groove first, it is possible to prevent the turbine rotor from coming off from the spindle in the axial direction.

[0097] (5) A medical cutting instrument according to any one of (1) to (4), The medical cutting instrument comprises: A medical cutting instrument equipped with a quick stop mechanism consisting of sealing members (sealing members 511, 512) that surround the outer peripheral surface of the spindle, abut against the outer peripheral surface of the spindle when the turbine rotor is not rotating, and move away from the outer peripheral surface of the spindle when the turbine rotor rotates at a predetermined speed or above.

[0098] According to (5), the quick-stop mechanism made of a sealing member can quickly stop the long-term inertial rotation that occurs when a material with a large moment of inertia is used for the turbine rotor. On the other hand, when the sealing member of the quick-stop mechanism comes into contact with the outer circumferential surface of the spindle, sudden braking places additional load on the joint of the rotating parts, but the grooves increase the adhesive strength of the joint, preventing the turbine rotor from falling off the spindle.

[0099] (6) A cartridge that can be detachably attached to the medical cutting instrument described in any one of (1) to (4), A cartridge comprising the rotating part.

[0100] According to (6), the adhesive strength of the joint that fixes the turbine rotor, which is made of a material with a large moment of inertia, to the spindle can be increased, and the turbine rotor and the spindle can be prevented from coming off.

[0101] (7) The cartridge according to (6), The cartridge comprises: A cartridge equipped with a quick stop mechanism consisting of a sealing member that surrounds the outer peripheral surface of the spindle, abuts against the outer peripheral surface of the spindle when the turbine rotor is not rotating, and moves away from the outer peripheral surface of the spindle when the turbine rotor rotates at a predetermined speed or higher.

[0102] According to (7), the quick stop mechanism made of a sealing member is provided, so that the long-term inertial rotation that occurs when a material with a large moment of inertia is used for the turbine rotor can be stopped in a short time. On the other hand, when the sealing member of the quick stop mechanism comes into contact with the outer circumferential surface of the spindle, a sudden brake is applied, and an additional load is placed on the joint of the rotating parts, but because the grooves create an increased adhesive strength at the joint, it is possible to prevent the turbine rotor and spindle from falling off.

[0103] (8) A medical cutting instrument having a rotating part having a turbine rotor and a spindle, The rotating part is a joint portion where an inner peripheral surface of the turbine rotor and an outer peripheral surface of the spindle are fixed with an adhesive; The joint is A medical cutting instrument having grooves on the inner peripheral surface of the turbine rotor and on the outer peripheral surface of the spindle.

[0104] According to (8), the adhesive strength of the joint that fixes the turbine rotor and the spindle can be further increased, and the turbine rotor and the spindle can be prevented from coming off.

[0105] (9) A medical cutting instrument according to (8), The joint is A medical cutting instrument, wherein grooves on the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle intersect with each other.

[0106] According to (9), the adhesive strength of the joint that fixes the turbine rotor and the spindle can be further increased. [Explanation of symbols]

[0107] 1. Air turbine handpiece (medical cutting instrument) 4 Rotating section 20 Head 30 cutting tools 40 cartridges 41 Spindle 415 Spindle outer surface 416 Groove 42 Turbine rotor 421 Rotating shaft part 422 Turbine blade section 425 Inner surface of turbine rotor 426 Groove 46 Joint 511, 512 Sealing member (quick stop mechanism)

Claims

1. A medical cutting instrument comprising a rotating part having a turbine rotor and a spindle, The turbine rotor has a density of 4.0 [g / cm ３ ] or more, Young's modulus [GPa] / density [g / cm ３ ] is formed of a metal having a value of 20 or more, the spindle has a hollow, generally cylindrical shape, its outer circumferential surface is rotatably supported by a bearing, and its inner circumferential surface is provided with a chuck mechanism, and a cutting tool can be inserted into the hollow interior; The rotating part is a joint portion where an inner peripheral surface of the turbine rotor and an outer peripheral surface of the spindle are fixed with an adhesive; The joint is grooves intersecting each other are provided on both the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle; A medical cutting instrument, wherein the resinified adhesive is fixed to the intersecting grooves.

2. A medical cutting instrument as described in claim 1, The joint is A medical cutting instrument, wherein the grooves on at least one of the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle are parallel to the circumferential direction.

3. A medical cutting instrument according to claim 1 or 2, The medical cutting instrument comprises: A medical cutting instrument comprising a quick stop mechanism consisting of a sealing member that surrounds the outer peripheral surface of the spindle, abuts against the outer peripheral surface of the spindle when the turbine rotor is not rotating, and moves away from the outer peripheral surface of the spindle when the turbine rotor rotates at a predetermined speed or above.

4. A cartridge that can be detachably attached to the medical cutting instrument described in either claim 1 or 2, A cartridge comprising the rotating part.

5. A cartridge according to claim 4, The cartridge comprises: A cartridge equipped with a quick stop mechanism consisting of a sealing member that surrounds the outer peripheral surface of the spindle, abuts against the outer peripheral surface of the spindle when the turbine rotor is not rotating, and moves away from the outer peripheral surface of the spindle when the turbine rotor rotates at a predetermined speed or higher.

6. A medical cutting instrument comprising a rotating part having a turbine rotor and a spindle, the spindle has a hollow, generally cylindrical shape, its outer circumferential surface is rotatably supported by a bearing, and its inner circumferential surface is provided with a chuck mechanism, and a cutting tool can be inserted into the hollow interior; The rotating part is a joint portion where an inner peripheral surface of the turbine rotor and an outer peripheral surface of the spindle are fixed with an adhesive; The joint is grooves intersecting each other are provided on both the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle; A medical cutting instrument, wherein the resinified adhesive is fixed to the intersecting grooves.

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