JPH0638983A - Water-lubricated bearing apparatus for dental handpiece - Google Patents

Abstract

PURPOSE:To achieve higher durability by forming at least one part among bearing components in a handpiece from a ceramic containing zirconium oxide while a misting means is interposed in an air supply path to obtain sufficient lubrication performance without use of oil. CONSTITUTION:In a dental handpiece, a turbine blade integrated with a rotation shaft rotating having a cutting tool mounted thereon is rotated by a compressed fluid to be supplied via an air supply path. The turbine blade and the rotation shaft are housed into a housing comprising a head housing 4 and a cap housing 5 and the rotation shaft is supported with a bearing. In this case, at least one part among a rolling element and inner and outer races composing the bearing is formed from a ceramic containing zirconium oxide while a holder is made of polyamideimide. A lubricator 50 is interposed in the course of the air supply path to introduce a mixture of air and mist water to be jetted from an orifice 54 in the Venturi's principle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-lubricated bearing device for a dental handpiece. More specifically, the present invention relates to a water-lubricated bearing device for a dental handpiece that can be lubricated with water to lubricate a bearing that supports a rotating shaft for holding a tool.

[0002]

2. Description of the Related Art Generally, a cutting or grinding tool for an air turbine type handpiece used for dentistry is rotated at a very high speed. In recent years, its rotation speed is 30
These bearings are used at high speeds of 50,000 to 500,000 rpm, and the bearings that support this rotating shaft are subject to wear and the like and require extremely severe durability. The rolling elements, outer ring, and inner ring that compose the bearing are usually made of special steel such as bearing steel.

These parts are so-called oils that are lubricated or oil sprayed with a lubricant, such as oil, at the time of cleaning or sterilizing the handpiece in order to provide durability by protecting them from friction and abrasion. Lubrication is performed to minimize friction of the bearing part.

However, when these lubrications are carried out by the adhesion of oil to the inside of the oral cavity during dental treatment, for example, when repairing a defective portion of a tooth or a denture, the scattered oil film adheres to the defective portion, It interferes with the adhesion, resulting in extremely poor adhesion. In addition, since the cutting or grinding tool of the handpiece rotates at high speed, the vibration is severe and the oil is scattered to the handle,
It is easy to slip from the handle part that the practitioner grips. Therefore, it may interfere with accurate treatment.

In particular, it is the worst when oil adheres to and promotes inflamed areas in the oral cavity. From such a thing,
It has been desired that the support of the rotary shaft can withstand the frictional force and maintain a sufficiently durable state even if oil or the like as a lubricant is removed. In response to such a demand, the rolling element (ball) of the bearing is formed of silicon nitride or ceramic mainly composed of sialon (Japanese Patent Laid-Open No. 63-22090).
No. 43 gazette and Tokuhyo Hyodai 4-500477) have been developed.

[0006] However, it is only one step from the viewpoint of wear resistance and durability, and especially when it is water-lubricated, its durability is inferior. In particular, the workability is not always sufficient. The bearings used in the handpiece are extremely small,
For example, some rolling elements have a diameter of less than 1 mm. Therefore, the bearing is required to be machined with a high machining precision, especially a high sphericity, but the above-mentioned materials do not always satisfy this requirement. In order to increase the sphericity, a material having a small surface roughness is required, and from that point of view, a material having better workability has been hungry.

[0007]

The present invention is intended to solve the above problems and achieves the following objects.

It is an object of the present invention to provide a water-lubricated bearing device for a dental handpiece that lubricates without using bearing lubricating oil or the like which is harmful to dental treatment.

Another object of the present invention is to provide a water-lubricated bearing device for a dental handpiece that is water-lubricated by using a zirconium oxide-based ceramic having good workability as a bearing material.

[0010]

[Means for Solving the Problems] To solve the above problems, the following means are adopted.

A rotating shaft for holding a tool, a turbine blade fixed to the rotating shaft, an air supply passage for flowing air for rotating the turbine blade, and an exhaust air for exhausting the air after rotating the turbine blade. An exhaust passage, a housing that encloses the rotating shaft and the turbine blade, a bearing that supports the rotating shaft in the housing, and the bearing is a rolling element, an inner ring, a dental handpiece including an outer ring,
At least one of the rolling element, the inner ring, and the outer ring is formed of a ceramic containing zirconium oxide, and the air supply passage is connected to a mist forming means for water-lubricating the bearing. It is a water-lubricated bearing device for a dental handpiece.

It is preferable that the rolling element is made of the ceramic containing zirconium oxide and the inner ring and the outer ring are made of martensitic stainless steel.

Further, the cage may be made of polyamide-imide.

Further, the mist forming means arranges a pipe on a case in which water is stored, and opens a water pipe arranged in the case into the air flowing through the pipe through the first orifice. It is advisable to adopt a structure having an adjusting screw for adjusting the size interval of the second orifice, which is opened in the air flowing through the pipe through the second orifice.

[0015]

[Function] At least one of the rolling element, the inner ring and the outer ring of the bearing that supports the rotating shaft of the dental handpiece is made of ceramics containing zirconium and the cage is made of polyamide-imide. Sufficient durability can be secured. By the mist-forming means, it is possible to easily change the supply air for rotating the turbine blade into a mist state.

[0016]

Embodiment 1 FIG. 1 is a view showing a dental handpiece bearing according to an embodiment of the present invention when a mist forming means for forming water into a mist and supplying the mist is connected. FIG. 2 is a sectional view of the main part of the head. The rotating shaft 1 is for rotating by attaching a tool for cutting or grinding, has a turbine blade 30 in the middle thereof, and rotates together with the rotation of the turbine blade 30. A turbine blade 30 is attached to the rotary shaft 1.
Bearings 2 and 3 are disposed on both sides of the rotary shaft 1 with the two bearings 2 and 3 interposed therebetween.

The turbine blade 30 and the rotary shaft 1 are housed in a housing H. In the case of this embodiment, the housing H
Is divided into a front and rear head housing 4 surrounding the front and a cap housing 5 surrounding the rear. The head housing 4 and the cap housing 5 are joined by a screw portion 6, and are joined so as to wrap the bearings 2, 3 and the turbine blade 30 from both sides. The housing H is divided into
It may be divided in the vertical direction in the figure, and the number of divisions is also arbitrary. In short, what is necessary is just to enclose the bearings 2 and 3 and the turbine blade 30.

The bearings 2 and 3 are mounted in a housing H. One bearing 2 is supported by the head housing 4 and the other bearing 3 is supported by the cap housing 5. O-rings 7 and 8 are fitted between the cap housing 5 and the bearing 3 and between the head housing 4 and the bearing 2, respectively, to seal and elastically support the rotary shaft 1 and the housing.

A wave washer 9 is interposed in the space between the head housing 4 and the bearing 2 and pushes the bearing 2 to the right in FIG. Therefore, the rotary shaft 1
Are elastically supported in the housing H by the wave washer 9 and the O-rings 7 and 8.

This is to give an appropriate preload to the bearing for normal rotation, and to prevent impact when contacting the local part of the tooth during treatment, and to minimize noise and vibration. To reduce. The structure of the bearings 2 and 3 is the same as a normal one, and includes a rolling element 42, an inner ring (inner race) 41, an outer ring (outer race) 43, and a cage (retainer) 44. As the cage 44, what is called a crown type cage in this embodiment is used.
The bearings 2 and 3 may not be provided depending on the type.
The other bearing 3 has a similar structure, and a description thereof will be omitted.

On the other hand, the housing 4 is connected to a handle portion 10 for the practitioner to hold by hand as an extension thereof, and is usually called a housing including the handle portion 10. An air supply passage 11 and an exhaust passage 12 are provided inside the handle portion 10. Compressed fluid introduced from the air supply passage 11, that is, air, is the turbine blade 30.
The air that hits and rotates it at a high speed and finishes the work is exhausted through the exhaust passage 12. The rotary shaft 1 has a cylindrical space 15 inside, and a tool is attached to the space 15 with a chuck tool (not shown) for use.

Next, the materials of the bearings 2 and 3 will be described. The material of the rolling element 42, which is each element of the bearings 2 and 3, is ceramics containing zirconium oxide. Steel or martensitic stainless steel was used for the inner race (inner race) 41 and the outer race (outer race) 43. By selecting such a material, it is possible to sufficiently lubricate a bearing made of a conventional steel material with water (usually distilled water) without using oil.

Further, it has the following great advantages as compared with a bearing made of ceramics containing silicon nitride or sialon. B) Since the rolling element made of ceramics containing zirconium oxide has extremely good workability, it is possible to perform precision processing with a small surface roughness and high sphericity. B)
Since there is little friction between the rolling elements made of ceramics containing zirconium oxide and the martensin-type stainless steel of the inner and outer rings, there is little wear and high durability.
C) Both materials are commercially available, so the price is low and easy to obtain.

When a polyamide-imide resin is used for the cage 44, low friction and low abrasion between the rolling element 42 made of ceramics containing zirconium oxide, the inner ring 41 and the outer ring 43 made of martensitic stainless steel, Higher durability can be demonstrated.

Mist Forming Means FIG. 1 is a schematic diagram of the mist forming means for connecting to the air supply passage 11 of the handpiece so as to atomize water and mix it with air to introduce into the handpiece.

A lubricator 50 for converting water into a mist will be described with reference to FIG. A hose (not shown) for supplying air is provided on the upper part of the case that stores water (normally distilled water), and is connected to the pipe 58. A water conduit 52 arranged in a case 51 for storing water is opened in the air flowing through a pipe 58 via a first orifice 53.

On the other hand, an opening is made in the pipe 58 through the second orifice 54. The adjusting screw 5 is to adjust the amount of water by adjusting the size interval of the second orifice 54.
7 Now, the air sent from the air source and flowing through the hose is the first orifice 5 according to the Venturi principle.
3 to the case 51. By this introduction, the water in the case 51 is sent to the upper part of the dropping window 56. The water is picked up by the second orifice 55 and atomized in the pipe 58, that is, misted.

The amount of water can be adjusted by the adjusting screw 57. The mist produced by the lubricator 50 is connected to the same system as the air supply passage 11 of the handpiece and used to rotate the turbine blade 30 of the handpiece. As described above, since the mist used for rotating the turbine blade 30 of the handpiece has a high pressure, it reaches the bearings 2 and 3 from the space around the turbine blade 30 and consequently the lubrication of the bearings 2 and 3 with water. Done.

That is, as described above, since the rolling elements of the bearings 2 and 3 are made of the ceramic containing zirconium oxide and the cage is made of the polyamide-imide resin, the frictional force is reduced and the durability is high. As a result, the lubrication with water is sufficient.

[0030]

[Embodiment 2] FIG. 4 is a sectional view of a main part of a dental water-lubricated handpiece according to another embodiment of the present invention. The difference from the above-mentioned dental water-lubricated handpiece is substantially the same except that the rotary shaft 1, the air supply passage 11 and the exhaust passage 12 are provided parallel to the direction of the handle portion 10.

[0031]

Third Embodiment FIG. 5 is a principle view showing another embodiment of the mist forming means. Connect the water supply line 60 to the handpiece,
An orifice 61 is provided between the air supply passage 11. When air is supplied to the air supply passage 11, the orifice 61
Water becomes mist on the principle of mist-blowing and flows into the air flow.

It is even more effective to provide a check valve or the like in the orifice 61. The merit of this structure is that the conventional metallic ball bearing can be replaced with a ceramic bearing without modifying the existing treatment device.

Although the embodiments have been described above, these are merely examples of the present invention, and various modifications may be made if necessary.
Needless to say, it can be changed.

[0034]

As described above in detail, according to the present invention, since the bearing is made of the ceramic containing zirconium oxide, the bearing made of the conventional bearing steel material can be sufficiently treated with water without using oil. Lubrication is possible. Further, it has the following great advantages over a bearing made of ceramics containing silicon nitride or sialon. I)
Since the workability is extremely good, small surface roughness and sphericity can be accurately obtained. (B) Ceramics containing zirconium oxide have good compatibility with martensitic stainless steel, low friction, and high durability. C) Both materials are commercially available, so they are easily available and inexpensive.

When a polyamide-imide resin is used for the cage, low friction, low wear, and high durability can be obtained between the rolling element made of ceramics containing zirconium oxide and the outer ring and inner ring made of stainless steel. Can be demonstrated. Further, the mist-forming means makes it possible to easily change the supply air for rotating the turbine blade into a mist state.

[Brief description of drawings]

FIG. 1 is a schematic view when a mist forming means is connected to a handpiece to atomize water and mix it with air, and then the water is introduced into the handpiece.

2 is a cross-sectional view of a main part of a water-lubricated bearing device for a dental handpiece, taken along line II-II in FIG.

FIG. 3 is a cross-sectional view of FIG. 2 taken along the line III-III.

FIG. 4 shows another embodiment of the present invention and is a cross-sectional view of a main part of a water-lubricated bearing device for a dental handpiece.

FIG. 5 is a cross-sectional view of a main part which is another embodiment of the mist forming means of the present invention.

[Explanation of symbols]

 1 ... Rotary shaft 2,3 ... Bearing 4 ... Head housing 7,8 ... O ring 9 ... Wave washer 11 ... Air supply passage 12 ... Exhaust passage 41 ... Inner ring 42 ... Rolling element 43 ... Outer ring 44 ... Cage 50 ... Lubricator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Teruzo Nakayama Inventor Teruzo 680 Higashihamanancho, Fushimi-ku, Kyoto-shi, Morita Manufacturing Co., Ltd. Morita Manufacturing Co., Ltd. (72) Inventor Akifumi Kamoi 4106, Miyota, Miyota-cho, Kitasaku-gun, Nagano 73 Minebea Co., Ltd. 1st Manufacturing Department

Claims (4)

[Claims] 1. A rotary shaft for holding a tool, a turbine blade fixed to the rotary shaft, an air supply passage for flowing air for rotating the turbine blade, and the air exhausted after rotating the turbine blade. An exhaust passage for, a housing that encloses the rotating shaft and the turbine blade, a bearing that supports the rotating shaft in the housing, and the bearing includes a rolling element, an inner ring, and an outer ring. At least one of the rolling element, the inner ring, and the outer ring is made of a ceramic containing zirconium oxide, and the air supply passage is connected to a mist forming means for water-lubricating the bearing. Water-lubricated bearing device for dental handpieces. 2. The dental water-lubricated handpiece according to claim 1, wherein the rolling element is formed of ceramics containing the zirconium oxide, and the inner ring and the outer ring are formed of martensitic stainless steel. Water-lubricated bearing device. 3. The water-lubricated bearing device for a dental handpiece according to claim 1, wherein the cage is made of polyamideimide. 4. The method according to claim 1, wherein the mist forming means arranges a pipe on a case in which water is stored, and a water guiding pipe is arranged in the case. 1 opening into the air flowing through the pipe through the orifice, opening into the air flowing through the pipe through the second orifice, and an adjusting screw for adjusting the size interval of the second orifice. Water-lubricated bearing device for dental handpieces.