Medical cutting instrument, and cartridge

Abstract

To provide: a medical cutting instrument capable of increasing a fixing force of a fixing part that fixes a spindle and a turbine rotor made of a material of a large moment of inertia such as stainless steel to each other, so as to prevent the spindle and the turbine rotor from falling; and a cartridge removably fitted to the medical cutting instrument.SOLUTION: A medical cutting instrument 1 includes a turbine rotor 42 and a spindle 41. The turbine rotor is formed of metal whose density is 4.0[g / cm3] or more and whose value of Young's modulus [GPa] / density [g / cm3] is 20 or more. The spindle has a hollow substantially cylindrical shape, and allows a cutting tool 30 to be inserted into a hollow portion. The turbine rotor and the spindle are formed of a same kind of metal. The medical cutting instrument comprises a weld part fixing the turbine rotor and the spindle by welding.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 removably 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 treatment, various medical cutting instruments such as air turbine handpieces and micromotor handpieces with cutting tools such as diamond point burs, carbide burs, files, and reamers attached to the head are used. 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 turbine rotor and a spindle housed in a head portion. The spindle has a hollow, generally cylindrical shape and is 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 turbine rotor is made of a metal (stainless steel) having a density of 4.0 [g / cm 3 ] or more. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-174901 A [Patent Document 2] Patent No. 7267495 Summary of the Invention [Problem to be solved by the invention]

[0007] However, such a turbine rotor made of stainless steel has a large moment of inertia, and therefore a large load is applied to the fixing part that fixes the turbine rotor to the spindle when a cutting load is applied, which may cause 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 disadvantage 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 removably attached to the medical cutting instrument, which can increase the fixing force of the fixing part that fixes the turbine rotor made of a material with a large moment of inertia, such as stainless steel, to the spindle, and prevent the turbine rotor from falling off from the spindle. [Means for solving the problem]

[0010] The first aspect of the present invention is A medical cutting instrument comprising a turbine rotor and a spindle, 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 turbine rotor and the spindle are formed from the same metal; The medical cutting instrument includes a welded portion that fixes the turbine rotor and the spindle by welding. Effect of the Invention

[0011] According to the present invention, it is possible to increase the fixing force of the fixing portion that fixes the turbine rotor, which is made of a material having a large moment of inertia, such as stainless steel, to the spindle. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a head portion of an air turbine handpiece including a turbine rotor and a spindle according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the turbine rotor and spindle of FIG. [Diagram 3] 2 is a schematic diagram showing a cartridge housed in a head portion of the air turbine handpiece of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of a medical cutting instrument according to the present invention and an air turbine handpiece as an example of a cartridge detachably attached to the medical cutting instrument will be described with reference to the accompanying drawings. Note that the drawings should be viewed in the direction indicated by the reference symbols.

[0014] [First embodiment] First, an air turbine handpiece 1 according to a first embodiment of the present invention will be described with reference to FIGS.

[0015] 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 tip portion of the handpiece body 10. A cutting tool 30 is removably attached to the head portion 20. A plurality of 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.

[0016] A cylindrical shaft portion 31 is formed at the tip 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. The tip of the cutting tool 30 (i.e., the tip 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.

[0017] Here, in this specification and the like, for the sake of concise and clear explanation, the axial direction of the shaft portion 31 of the cutting tool 30 in the air turbine handpiece 1 in which the cutting tool 30 is attached to the head portion 20 is defined as the X direction for the sake of convenience. The tip end side of the cutting tool 30 (i.e., the tip end side of the shaft portion 31) is defined as the X1 side, and the other end side of the cutting tool 30 is defined as the X2 side. Furthermore, unless otherwise specified, the axial direction, circumferential direction, and radial direction refer to directions based on the axial direction of the shaft portion 31.

[0018] Therefore, the 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 protrudes from the head portion 20 in the X2 direction.

[0019] 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 is open 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.

[0020] The internal storage space 200 of the head unit 20 accommodates a cartridge 40 in which a spindle 41 having a hollow, generally cylindrical shape extending in the X direction, a turbine rotor 42 fixed to a fixing portion 43 on the outer circumferential surface of the spindle 41, 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 are modularized. In this embodiment, the cartridge 40 is detachable from the head unit 20. 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. In addition, a plurality of 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, etc.

[0021] 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.

[0022] An X1 side end of the spindle 41 is rotatably supported by a first bearing 451. An X2 side end of the spindle 41 is rotatably supported by a second bearing 452. The first bearing 451 is fixed to an 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 an inner circumferential surface of the main housing 21 via an O-ring 492.

[0023] The turbine rotor 42 has a substantially cylindrical rotating shaft portion 421 fixed to the outer circumferential surface of the spindle 41, and a plurality of turbine blade portions 422 each having a blade shape and extending radially outward with respect to the axial direction of the rotating shaft portion 421. 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 together. 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.

[0024] The chuck mechanism 44 has a hollow, generally cylindrical shape, and includes a chuck portion 441 that is fitted and supported by the inner circumferential surface of the spindle 41, and a pusher 442 that is provided at the X1 side end of the spindle 41 and operates the chuck portion 441. The cutting tool 30 is supported by the chuck portion 441 so as not to be misaligned in the radial direction with respect to the spindle 41.

[0025] 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.

[0026] 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 portion 441 opens.

[0027] 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 the chuck unit 441 to be maintained in an open state and capable of receiving the cutting tool 30. Then, while maintaining the chuck unit 441 in an 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 is abutted against the chuck mechanism unit 44. Then, when the user releases the push button 23 while the tip of the shaft unit 31 of the cutting tool 30 is abutted against the chuck mechanism unit 44, the pusher 442 slides toward the X1 side and the chuck unit 441 is closed while holding the shaft unit 31 of the cutting tool 30, and the cutting tool 30 is attached to the head unit 20 via the cartridge 40 while being maintained in a state held by the chuck mechanism unit 44. This allows the cutting tool 30 to rotate integrally with the spindle 41 and the turbine rotor 42.

[0028] 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 by 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 removed from the chuck mechanism 44 and removed from the head unit 20.

[0029] The handpiece body 10 includes a supply duct (not shown) that supplies high-pressure air (compressed air) that is the working gas of the turbine rotor 42 to the head portion 20, and an exhaust duct (not shown) that discharges the high-pressure air supplied to the head portion 20 to the outside. The high-pressure air supplied to the head portion 20 is discharged to the outside not only from the exhaust duct but also from gaps generated between the outer circumferential surface of the spindle 41 and contact pieces 511b, 512b of sealing members 511, 512, which will be described later.

[0030] The 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. The turbine blade portion 422 of the turbine rotor 42 receives the high-pressure air, causing the turbine rotor 42 to rotate. As a result, the spindle 41 and the cutting tool 30 rotate integrally with the turbine rotor 42.

[0031] The turbine rotor 42 is made of a metal with a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more. 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].

[0032] In this way, the turbine rotor 42 is made of a metal having a density of 4.0 [g / cm3] or more, which can increase the moment of inertia of the turbine rotor 42. This can reduce a sudden increase in the rotation 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, and can reduce the load on the first bearing 451 and the second bearing 452. In addition, when a cutting load is input to the turbine rotor 42 via the cutting tool 30 during rotation of the turbine rotor 42, it can prevent the turbine rotor 42 from stalling and the cutting force of the cutting tool 30 from decreasing.

[0033] Furthermore, the turbine rotor 42 has a Young's modulus [GPa] / density [g / cm3] value of 20 or more. In general, when the same force acts on objects of the same shape but different Young's modulus, the larger the Young's modulus, the smaller the deformation. When the same rotation is applied to objects of the same shape but different density, the larger the force acting on the object is, the larger the density is. Therefore, the larger the Young's modulus and the lower the density, the smaller the deformation amount due to rotation. In this embodiment, the turbine rotor 42 has a Young's modulus [GPa] / density [g / cm3] value of 20 or more, so that the deformation amount 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 suppressed from expanding, and the fixation between the turbine rotor 42 and the spindle 41 can be prevented from loosening.

[0034] Furthermore, in the air turbine handpiece 1, the center of gravity can be moved closer to the head portion 20, so that the natural frequency of the turbine rotor 42 increases 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 makes it possible to reduce unpleasant noise generated from 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.

[0035] In the present embodiment, the turbine rotor 42 is made of stainless steel. More specifically, in the present embodiment, the turbine rotor 42 is made of SUS303, which is an austenitic stainless steel.

[0036] In this way, since the turbine rotor 42 is formed from stainless steel, which is an easily machined material, the turbine rotor 42 can be easily molded.

[0037] In addition, the turbine rotor 42 is made of austenitic stainless steel, which is a material that does not easily corrode even when washed with hot water, and therefore has excellent corrosion resistance. Therefore, it is not necessary to perform surface treatment to improve the corrosion resistance of the turbine rotor 42, such as coating with anodized aluminum.

[0038] The turbine rotor 42 is made of a metal with a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more, and has a larger moment of inertia than conventional aluminum, so the inertia force of the turbine rotor 42 during rotation is also large. Therefore, when a cutting load is input, the spindle 42 is stopped through the cutting tool 30, and a load in the opposite direction to the rotation direction is generated on the fixing part 43 that fixes the turbine rotor 42 and the spindle 41. If the fixing force between the turbine rotor 42 and the spindle 41 decreases, the spindle 41 will easily move in the axial direction when a load acts in the axial direction such that a cutting load is input, and there is a risk of malfunction due to heat generation or poor attachment / detachment of the cutting tool.

[0039] As shown in FIG. 2, at a fixing portion 43 that fixes the turbine rotor 42 and the spindle 41, the turbine rotor 42 is fixed to the outer peripheral surface of the spindle 41, and the turbine rotor 42 has a welded portion 431 at the rotating shaft portion 421 that is fixed to the spindle 41 by welding.

[0040] In this embodiment, the welded portion 431 is provided on the outer circumferential surface of the rotating shaft portion 421 by spot welding. The spot welding method is preferably laser welding, and the number of spot welds on the outer circumferential surface of the rotating shaft portion 421 is preferably at least one. It is particularly preferable that the spot welds are arranged at equal intervals in the circumferential direction, 180° apart when there are two spot welds, and 120° apart when there are three spot welds, thereby preventing instability in the rotation direction during high-speed rotation. By employing spot welding, the welded portion 431 can be easily provided, which leads to a reduction in work time and cost.

[0041] The turbine rotor 42 and spindle 41 fixed by the welded portion 431 are made of the same metal. The term "same metal" refers to metals with similar thermal conductivity and melting points, and in the case of stainless steel, the same metal includes, for example, SUS303, SUS416, SUS420, and SUS440C. Conventionally, the turbine rotor 42 has generally been made of aluminum, and therefore it was not suitable to fix the turbine rotor 42 to the spindle 41 made of stainless steel by welding. However, in the present invention, the turbine rotor 42 and spindle 41 are made of the same metal, and therefore welding can be easily performed.

[0042] Furthermore, in this embodiment, a protrusion 426 is formed at a portion where the rotating shaft portion 421 of the turbine rotor 42 contacts the second bearing 452. The protrusion 426 extends radially outward from the rotating shaft portion 421, thereby stabilizing the engagement between the turbine rotor 42 and the contacting second bearing 452 and preventing the second bearing 452 from vibrating in the axial direction.

[0043] The protrusion 426 extends radially outward to the cage 452f of the second bearing 452. This allows the supplied high-pressure air to be discharged from the gap between the outer ring 425b of the second bearing 452 and the cage 452f toward the gap generated between the contact pieces 511b, 512b of the seal members 511, 512 and the outer circumferential surface of the spindle 41.

[0044] In this embodiment, the welded portion 431 is spot welded, but the present invention is not limited to this, and for example, the inner peripheral surface of the rotating shaft portion 421 and the outer peripheral surface of the spindle 41 may be fixed to each other by fillet welding over the circumferential direction. Laser welding is preferably used as the fillet welding method.

[0045] In addition, in this embodiment, the rotating shaft portion 421 and the turbine blade portion 422 of the turbine rotor 42 are formed of the same metal, but the rotating shaft portion 421 and the turbine blade portion 422 may be formed of different materials, or only the rotating shaft portion 421 may be formed of the same metal as the spindle 41. For example, the rotating shaft portion 421 and the spindle 41 may be made of stainless steel having a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more, and the turbine blade portion 422 may be made of aluminum or resin.

[0046] Furthermore, in this embodiment, the welded portion 431 is provided on the X2 side (the other end side of the cutting tool 30) where the second bearing 452 is provided, but the welded portion 431 may be provided on the X1 side (the tip side of the cutting tool 30) where the first bearing 451 is provided, or on both sides.

[0047] In this way, since the fixing portion 43 that fixes the turbine rotor 42 and the spindle 41, which are made of the same metal, is provided with the welded portion 431, it is possible to increase the fixing force of the fixing portion 43 that fixes the turbine rotor 42 and the spindle 41, which are subjected to a large load when a cutting load is input. This prevents the turbine rotor 42 from falling off the spindle 41.

[0048] The first bearing 451 has an inner ring 451a and an outer ring 451b facing each other, a ball 451c located in a gap between the inner ring 451a and the outer ring 451b, and a retainer 451f that holds the ball 451c.

[0049] 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.

[0050] An extension portion 451e is formed at the X2 side end of the outer ring 451b of the first bearing 451 to extend radially outward and support the O-ring 491 from the X2 side.

[0051] 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 circumferential surface of the spindle 41. Therefore, the inner ring 451a rotates together with the spindle 41.

[0052] A seal retaining member 521 is attached to the X1 side of the outer ring 451b of the first bearing 451. The seal retaining member 521 is engaged with the outer peripheral surface of the outer ring 451b of the first bearing 451. The seal retaining 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 and 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.

[0053] The seal member 511 is made of an elastic material. The seal member 511 is made of, for example, silicon rubber or fluororubber. The seal member 511 may be made of an elastic material other than silicon rubber and fluororubber. The seal member 511 has a ring shape that surrounds the outer circumferential surface of the spindle 41 and has an opening at the center. The seal member 511 includes an outer circumferential part 511a that is the thickest, and a contact piece 511b that extends from the inner edge of the outer circumferential part 511a toward the center of the ring. The contact piece 511b has a lower elastic modulus than the outer circumferential part 511a and is easily elastically deformed. In the seal member 511, a ring opening 511c is opened at the center of the ring further than the contact piece 511b.

[0054] The outer circumferential portion 511a of the seal member 511 is supported on the X1 side by the clamping portion 521b of the seal retaining 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 retaining member 521 and the clamping portion 451d of the first bearing 451.

[0055] The contact piece 511b of the seal member 511 is disposed in a space surrounded by the inner circumferential surface of the clamping portion 521b of the seal holding member 521 and the outer circumferential 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 from the supply duct of the handpiece body 10 to the head portion 20, the contact piece 511b is in contact with the outer circumferential surface of the spindle 41.

[0056] 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 from the supply duct of the handpiece body 10 to the head portion 20, the contact piece 511b of the seal member 511 is curved toward the X1 side and comes into contact with the outer circumferential surface of the spindle 41 by contact pressure due to 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.

[0057] In this way, when high-pressure air is not being 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.

[0058] This makes it possible to prevent foreign matter such as saliva or blood from entering the inside of the cartridge 40.

[0059] The second bearing 452 has an inner ring 452a and an outer ring 452b facing each other, a ball 452c located in a gap between the inner ring 452a and the outer ring 452b, and a retainer 452f that holds the ball 452c.

[0060] 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.

[0061] An extension portion 452e is formed at the X1 side end of the outer ring 452b of the second bearing 452 to extend radially outward and support the O-ring 492 from the X1 side.

[0062] 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 circumferential surface of the spindle 41. Therefore, the inner ring 452a rotates together with the spindle 41.

[0063] A seal retaining member 522 is attached to the X2 side of the outer ring 452b of the second bearing 452. The seal retaining member 522 is engaged with the outer peripheral surface of the outer ring 452b of the second bearing 452. The seal retaining 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 to 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 to the X1 side and 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.

[0064] The seal member 512 is made of an elastic material. The seal member 512 is made of, for example, silicon rubber or fluororubber. The seal member 512 may be made of an elastic material other than silicon rubber and fluororubber. The seal member 512 has a ring shape that surrounds the outer circumferential surface of the spindle 41 and has an opening at the center. The seal member 512 includes an outer circumferential part 512a that is the thickest, and a contact piece 512b that extends from the inner edge of the outer circumferential part 512a toward the center of the ring. The contact piece 512b has a lower elastic modulus than the outer circumferential part 512a and is easily elastically deformed. In the seal member 512, a ring opening 512c is opened at the center of the ring further than the contact piece 512b.

[0065] The outer circumferential portion 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 retaining member 522, and is clamped between the clamping portion 452d of the second bearing 452 and the clamping portion 522b of the seal retaining member 522.

[0066] The contact piece 512b of the seal member 512 is disposed in a space surrounded by the inner circumferential surface of the clamping portion 522b of the seal holding member 522 and the outer circumferential 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 from the supply duct of the handpiece body 10 to the head portion 20, the contact piece 512b is in contact with the outer circumferential surface of the spindle 41.

[0067] The diameter of the ring opening 512c of the seal member 512 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 from the supply duct of the handpiece body 10 to the head portion 20, the contact piece 512b of the seal member 512 is curved toward the X2 side and comes into contact with the outer circumferential surface of the spindle 41 by contact pressure due to elastic force. The position where the contact piece 512b comes into contact with the outer circumferential surface of the spindle 41 is the opening edge of the ring opening 512c.

[0068] In this way, when high-pressure air is not being 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.

[0069] This makes it possible to prevent foreign matter such as saliva or blood from entering the inside of the cartridge 40.

[0070] 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 above, air leaks from the internal accommodating space 200 through the first bearing 451 into the space in which the contact piece 511b of the sealing member 511 is located, and leaks through the second bearing 452 into the space in which the contact piece 512b of the sealing member 512 is located.

[0071] Then, the contact piece 511b of the seal member 511 is pushed outward in the radial direction of the spindle 41 by the air leaking into the space in which the contact piece 511b of the seal member 511 is located, and the contact piece 511b of the seal member 511 is separated from the outer peripheral surface of the spindle 41, creating a gap between the contact piece 511b of the seal member 511 and the outer peripheral surface of the spindle 41.

[0072] Similarly, the contact piece 512b of the seal member 512 is pushed outward in the radial direction of the spindle 41 by air leaking into the space in which the contact piece 512b of the seal member 512 is located, causing the contact piece 512b of the seal member 512 to separate from the outer peripheral surface of the spindle 41, and creating a gap between the contact piece 512b of the seal member 512 and the outer peripheral surface of the spindle 41.

[0073] 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 the 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 circumferential surface of the spindle 41, and between the contact piece 512b of the seal member 512 and the outer circumferential surface of the spindle 41, so that the spindle 41 is free from contact resistance with the contact piece 511b of the seal member 511 and the contact piece 512b of the seal member 512, and becomes easily rotatable.

[0074] On the other hand, 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, spindle 41, and cutting tool 30 are rotating 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 contact piece 511b of seal member 511 and the space in which contact piece 512b of seal member 512 are located decreases, and when the rotational speed of the turbine rotor 42 drops below a predetermined speed, contact piece 511b of seal member 511 and contact piece 512b of 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, the spindle 41, and the cutting tool 30 is braked by the contact resistance between the contact piece 511b of the seal member 511 and the outer circumferential surface of the spindle 41 and the contact resistance between the contact piece 512b of the seal member 512 and the outer circumferential 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, the spindle 41, and the 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. As a result, the seal members 511 and 512 can stop the rotation of the turbine rotor 42, the spindle 41, and the 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 unit 20 is stopped.

[0075] In addition, the air turbine handpiece 1 is provided with sealing members 511 and 512 which also function as a quick-stop mechanism for braking 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.

[0076] 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, the braking force for braking the rotation of the turbine rotor 42, the spindle 41, and the cutting tool 30 can be increased when the supply of high-pressure air from the supply duct of the handpiece body 10 to the head portion 20 is stopped.

[0077] 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.

[0078] Furthermore, the air turbine handpiece 1 is used after injecting a lubricant into the head portion 20. Therefore, the air turbine handpiece 1 is used with each internal part of the head portion 20 coated with a lubricant. For example, first, a sufficient amount of lubricant is injected into the head portion 20 from the supply duct of the handpiece body 10 to remove dirt adhering to each internal part of the head portion 20 and to create a state in which each internal part of the head portion 20 is coated with a lubricant, and then the excess lubricant is removed before using the air turbine handpiece 1.

[0079] This can prevent malfunctions of the components inside the head unit 20 due to adhesion of dirt, and can prevent wear of the first bearing 451 and the second bearing 452. In addition, since the outer peripheral surface of the spindle 41 and the seal members 511 and 512 are also coated with the lubricant when the air turbine handpiece 1 is in use, when the turbine rotor 42, spindle 41, and cutting tool 30 are rotated together, the supply of high-pressure air from the supply duct of the handpiece body 10 to the head unit 20 is stopped, and wear of the contact pieces 511b and 512b of the seal members 511 and 512 can be suppressed 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 when the rotation of the turbine rotor 42, spindle 41, and cutting tool 30 is braked.

[0080] 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 the sealing members 511, 512 of the quick-stop mechanism come into contact with the outer circumferential surface of the spindle 41, sudden braking is applied, and an additional load is applied to the fixing portion 43 that fixes the inner circumferential surface of the turbine rotor 42 and the outer circumferential surface of the spindle 41. However, since the fixing portion 43 that fixes the turbine rotor 42 and the spindle 41, which are made of the same metal, is provided with the welded portion 431, it is possible to prevent the turbine rotor 42 and the spindle 41 from falling off.

[0081] Although the embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modified or amended examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. In addition, the components in the above embodiment may be arbitrarily combined within the scope of the invention.

[0082] For example, in the turbine rotor 42 and the spindle 41 of this embodiment, a metal such as titanium may be used instead of stainless steel.

[0083] Also, for example, in this embodiment, 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 increase the braking force that brakes the rotation of the turbine rotor 42, the spindle 41, and the 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] Also, for example, in this embodiment, 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, 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, 512 do not have to be modularized.

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

[0086] This specification describes at least the following items. In parentheses, components corresponding to the above-described embodiment are shown as examples, but the present invention is not limited to these.

[0087] (1) A medical cutting instrument comprising 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 turbine rotor and the spindle are formed from the same metal; A medical cutting instrument comprising a welded portion (welded portion 431) that fixes the turbine rotor and the spindle by welding.

[0088] According to (1), the fixing force of the fixing part that fixes the spindle to the turbine rotor, which is made of a metal with a large moment of inertia, that is, a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more, can be increased, thereby preventing the turbine rotor from falling off from the spindle.

[0089] (2) A medical cutting instrument as described in (1), The turbine rotor has a substantially cylindrical rotating shaft portion (rotating shaft portion 421) and a plurality of turbine blade portions (turbine blade portions 422) each having a blade shape and extending radially outward with respect to an axial direction of the rotating shaft portion, A medical cutting instrument in which at least the rotating shaft portion of the turbine rotor and the spindle are formed from the same metal having a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more.

[0090] According to (2), since a welded portion is provided at the fixing portion that fixes the rotating shaft portion of the turbine rotor and the spindle, the fixing force of the fixing portion can be increased and the turbine rotor and the spindle can be prevented from falling off.

[0091] (3) A medical cutting instrument as described in (2), A medical cutting instrument comprising a welded portion that fixes a rotating shaft portion of the turbine rotor and the spindle by spot welding.

[0092] According to (3), since the welded portion is provided by spot welding, the rotating shaft portion of the turbine rotor and the spindle can be easily fixed together, which leads to a reduction in work time and costs.

[0093] (4) A medical cutting instrument as described in (3), A medical cutting instrument, wherein the rotating shaft portion of the turbine rotor has a convex portion (convex portion 426) formed at a portion that abuts against a bearing.

[0094] According to (4), the engagement between the turbine rotor and the bearing in contact therewith is stabilized, and axial vibration of the bearing is prevented.

[0095] (5) A medical cutting instrument according to (4), The protrusion extends radially outward to a bearing retainer (451f, 452f).

[0096] According to (5), the supplied high-pressure air can be discharged from the gap between the outer ring of the bearing and the cage toward the gap formed between the contact piece of the sealing member and the outer peripheral surface of the spindle.

[0097] (6) A medical cutting instrument according to (5), A medical cutting instrument, wherein at least the rotating shaft portion of the turbine rotor and the spindle are formed of stainless steel.

[0098] According to (6), since the rotating shaft portion of the turbine rotor and the spindle are formed of the same metal, that is, stainless steel, welding parts can be easily provided.

[0099] (7) A medical cutting instrument according to any one of (1) to (6), The medical cutting instrument comprises: A medical cutting instrument equipped with a quick-stop mechanism consisting of a sealing member (sealing members 511, 512) that surrounds the outer peripheral surface of the spindle, abuts 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.

[0100] According to (7), since the quick-stop mechanism made of a sealing member is provided, it is possible to 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 spindle, the fixing part is subjected to an additional load due to sudden braking, but the fixing force of the fixing part that fixes the turbine rotor and the spindle is increased by the welded part provided on the fixing part, so it is possible to prevent the turbine rotor and the spindle from falling off.

[0101] (8) A cartridge (cartridge 40) that is detachably attached to the medical cutting instrument according to any one of (1) to (6), A cartridge comprising the turbine rotor and the spindle.

[0102] According to (8), the fixing force of the fixing portion that fixes the turbine rotor, which is made of a material having a large moment of inertia, to the spindle can be increased, thereby preventing the turbine rotor from falling off the spindle.

[0103] (9) A cartridge according to (8), The cartridge comprises: A cartridge 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 higher.

[0104] According to (9), since the quick-stop mechanism made of a sealing member is provided, it is possible to 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 spindle, the fixing part is subjected to an additional load due to sudden braking, but the fixing force of the fixing part that fixes the turbine rotor and the spindle is increased by the welded part provided on the fixing part, so it is possible to prevent the turbine rotor and the spindle from falling off. [Explanation of symbols]

[0105] 1. Air turbine handpiece (medical cutting instrument) 4 Rotating section 20 Head section 30 cutting tools 40 Cartridge 41 Spindle 42 Turbine rotor 421 Rotating shaft part 422 Turbine blade section 426 Convex 43 Fixed part 431 Welding 451 First bearing 452 Second bearing 451f, 452f retainer 511, 512 Sealing member (quick stop mechanism)

Claims

1. A medical cutting instrument comprising a turbine rotor and a spindle, 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] value 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 turbine rotor and the spindle are formed from the same metal; A medical cutting instrument comprising a welded portion that fixes the turbine rotor and the spindle by welding.

2. 2. The medical cutting instrument of claim 1, The turbine rotor has a substantially cylindrical rotating shaft portion and a plurality of turbine blade portions each having a blade shape and extending radially outward with respect to an axial direction of the rotating shaft portion, A medical cutting instrument in which at least the rotating shaft portion of the turbine rotor and the spindle are formed from the same metal having a density of 4.0 [g / cm3] or more and a Young's modulus [GPa] / density [g / cm3] value of 20 or more.

3. 3. The medical cutting instrument of claim 2, A medical cutting instrument comprising a welded portion that fixes a rotating shaft portion of the turbine rotor and the spindle by spot welding.

4. 4. The medical cutting instrument of claim 3, A medical cutting instrument, wherein a rotary shaft portion of the turbine rotor has a convex portion formed at a portion that abuts against a bearing.

5. 5. The medical cutting instrument according to claim 4, A medical cutting instrument, wherein the protrusion extends radially outward to a retainer of a bearing.

6. 6. The medical cutting instrument according to claim 5, A medical cutting instrument, wherein at least the rotating shaft portion of the turbine rotor and the spindle are formed of stainless steel.

7. A medical cutting instrument according to any one of claims 1 to 6, 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 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.

8. A cartridge removably attached to the medical cutting instrument according to any one of claims 1 to 6, comprising: A cartridge comprising the turbine rotor and the spindle.

9. 9. The cartridge of claim 8, The cartridge comprises: A cartridge 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 higher.

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