WO2017018226A1

WO2017018226A1 - Dental handpiece

Info

Publication number: WO2017018226A1
Application number: PCT/JP2016/070802
Authority: WO
Inventors: 守新飯田; 智熊地; 健嗣長谷川
Original assignee: 株式会社吉田製作所
Priority date: 2015-07-24
Filing date: 2016-07-14
Publication date: 2017-02-02
Also published as: JP6734634B2; JP2017023505A

Abstract

The purpose of the present invention is to provide a dental handpiece that can, on the basis of a simple and inexpensive configuration, precisely prevent fall off of a cover body due to the loosening of the screw attachment of the cover body which is screw-connected to a handpiece head part. The present invention provides a dental handpiece (1) which comprises a cartridge housing (21) that detachably holds therein a rotationally driven cutting tool (22) and that is disposed inside of an accommodation region (4) of a handpiece head part (2), wherein: a screw connection is established between a male screw thread (16) of a cover body (11) which is screwed onto the handpiece head part (2) and a female screw thread (6) of the handpiece head part (2); a first recessed groove (15) that enables free fitting of the inner circumferential-section side of a C-ring (17), which is a ring-shaped elastic member, is provided at a male screw-thread end section provided to a peripheral wall part (12) of the cover body (11); a second recessed groove (5) that accommodates the outer circumferential-section side of the C-ring (17) and that is disposed opposing the first recessed groove (15) when the cover body (11) is screwed onto the handpiece head part (2) is provided at a female screw-thread advancement section provided to the handpiece head part (2); and a contact resistance force is generated by the C-ring (17) when the screw attachment of the cover body (11) becomes loose, thereby preventing the fall off of the cover body (11).

Description

Dental handpiece

The present invention relates to a dental handpiece, and more particularly, to a dental handpiece that prevents the lid that is screw-coupled to the handpiece head portion from falling off due to screw loosening.

In a dental handpiece, when opening and closing a lid screwed to the handpiece head portion for replacement of internal parts such as a cartridge housing in the handpiece head portion, the lid body may loosen and fall off. .

For this reason, in the past, a binding mechanism or an adhesive was applied to the screw of the lid to fix the lid to prevent the cap from falling off. In many cases, the lid body loosened and dropped off due to deterioration or peeling of the adhesive.

In addition, there are products that use a small screw, which is a separate part, to fix the lid. However, depending on the case, the lid may not be fixed due to loss or damage of the small screw, or may come off after the small screw is fixed. It is assumed that it is difficult to reliably prevent the lid from falling off in the dental handpiece.

If it is a factory repair, it is possible to add a loosening prevention mechanism to the screw part and reprocess the adhesive, etc., but reprocessing is difficult in the case of local replacement at the user site.

In Patent Document 1, a lid body that covers the top of a cartridge housing mounted in the handpiece head portion is detachably fitted to the upper portion of the handpiece head portion. The cartridge housing is brought into contact with the upper surface of the rotation shaft in the cartridge housing, and the cartridge housing is directed downward via the rotation shaft by a coil spring disposed below the inner bottom of the lid and around the rotation shaft. That is, a cartridge-type dental handpiece configured to be biased so as to be integrated with the handpiece head portion is disclosed.

However, in the case of the dental handpiece of Patent Document 1, a configuration in which a lid covering the upper part of the cartridge housing mounted therein is detachably fitted to the handpiece head portion by, for example, screw connection. No particular consideration is given to the looseness of the screw with respect to the handpiece head portion of the lid.

Patent Document 2 discloses a dental system having a housing, a chuck mechanism rotatably mounted in the housing, a bearing for rotatably fixing the chuck mechanism in the housing, and an inner lid that supports the bearing. In the handpiece head for use, the inner lid is composed of two cascade-coupled inner lid members having screwed screws that are screwed into the inner peripheral portion of the housing, and the two inner lid members are connected to the screwed screws. Discloses a head part structure of a dental handpiece configured to be integrated into a concave part of a mating part through a threaded screw part screwed in the opposite direction.

However, in the case of the head part structure of a dental handpiece disclosed in Patent Document 2, the structure of the upper inner lid and the upper inner lid is further complicated although the loosening of the two inner lid members can be realized. The upper lid that is disposed above and covers the upper end side of the housing and the upper lid integral with each other are screwed together, and no particular consideration is given to the loosening of the upper lid.

JP 2014-90892 A Japanese Patent Laid-Open No. 10-211121

The problem to be solved by the present invention is to accurately prevent the lid that is screw-coupled to the handpiece head part from being loosened due to a simple and inexpensive configuration that does not use a complicated locking mechanism or adhesive. There is no dental handpiece to obtain.

The present invention relates to a dental handpiece comprising a cartridge housing that holds a cutting tool that is rotationally driven in a projecting state from the center portion of the lower end surface and is detachably held in a receiving area of the handpiece head portion. The male screw of the lid that covers the upper part of the lid and the female screw of the handpiece head part are detachable threadedly connected, and a ring-shaped elastic member is provided at the end of the male screw provided on the peripheral wall of the lid When the lid is screwed to the handpiece head part at the female screw insertion end provided in the handpiece head part, the first concave groove for loosely fitting the inner peripheral side of the member is the first concave shape. A second concave groove that is disposed opposite to the groove and accommodates the outer peripheral side of the ring-shaped elastic member is provided, and the ring-shaped elastic member that is displaced in conjunction with the screw loosening of the lid body is displaced. First , The most important feature that has a structure that causes the contact resistance due to contact with the inner wall of the second recessed grooves.

According to the first aspect of the present invention, based on a simple and inexpensive structure in which a ring-shaped elastic member is interposed between the first concave groove on the lid side and the second concave groove on the handpiece head portion side, The contact resistance force of the elastic member in the loosened state eliminates the necessity of providing a screw loosening prevention structure such as an adhesive as in the conventional example, and even if the lid body is in the loosened state, the cover member will fall off completely. A dental handpiece that can be accurately prevented can be provided.

According to the second aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, and the inner periphery of the upper cylindrical portion of the handpiece head portion can be arranged from the upper end to the vicinity of the upper end of the second concave groove. By providing a counterbore portion having a downwardly inclined shape extending to the ring shape, the ring-shaped elastic member loosely fitted in the first concave groove of the lid body during the screwing operation of the lid body can be smoothly and without any trouble. It is possible to provide a dental handpiece that can face the concave groove and exert contact resistance force in a screw loose state.

According to the invention described in claim 3, in addition to the configuration of the invention described in claim 2, it is screwed into the handpiece arm receiving portion connected to the outside of the upper cylindrical portion of the handpiece head portion, and the outer periphery of the head portion As a configuration with a lid holding screw that abuts against the peripheral wall of the lid and holds it to the upper cylindrical portion side, if the lid holding screw is forgotten to be attached or dropped off, and the lid screw is loosened. Even when such a situation occurs, the contact resistance force in the screw loose state of the elastic member can prevent further screw loosening of the lid, and if this state is maintained, the product due to the screw loosening of the lid Thus, the dental handpiece can be provided that allows the user to detect the looseness of the screw of the lid body due to the abnormal noise or vibration of the lid and prevent a major accident due to the falling off of the lid body.

According to invention of Claim 4, the dental handpiece which can exhibit the effect of the invention in any one of Claims 1 thru | or 3 as said ring-shaped elastic member as C ring or O-ring is provided. can do.

According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the elastic member comprising the C-ring or the O-ring has a substantially polygonal outer periphery and a plurality of corners. And the C-ring is made evenly with respect to the center of the upper cylindrical portion by making the inner peripheral wall of the second concave groove of the handpiece head portion contact each corner portion. Even if the lid body is loosened, the C-ring or O-ring is difficult to be removed from the second concave groove, and even if the lid body is loosened, its complete removal is prevented. A dental handpiece that can be accurately prevented can be provided.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the material of the elastic member made of the C ring or O ring is stainless steel. Therefore, it is possible to provide a dental handpiece having specifications that can exhibit superior durability and can be used for an autoclave.

According to the invention of claim 7, the elastic member is formed by bending a stainless steel wire to have a shape having an expansion / contraction function as a whole, and a plurality of bending bulges bulging outward with respect to the stainless steel wire. An elastic member is provided at the upper end based on a configuration in which protrusions are provided in a separate arrangement, and the outer peripheral side of each bent bulge protrusion is brought into contact with a wall surface defining a concave groove as a target portion in a non-continuous separation arrangement. Even if the screw of the lid is loosened, the elastic member is difficult to come out of the concave groove, and even if the lid is in the loosened state, it will be completely arranged. It is possible to provide a dental handpiece that can accurately prevent the dropout.

FIG. 1 is an exploded perspective view of a handpiece head portion in a dental handpiece according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the lid and the C-ring that are screwed into the handpiece head portion of the dental handpiece according to the present embodiment. FIG. 3 is a partial enlarged cross-sectional view showing a handpiece head portion, a lid, and a C-ring which is an elastic member in the dental handpiece according to the present embodiment. 4A and 4B are partially enlarged cross-sectional views showing the portion A shown in FIG. 3 further enlarged. FIG. 4A shows the screw tightened state of the lid, and FIG. 4B shows the screw loosened state of the lid. It is. FIG. 5 is a partial cross-sectional view showing a screw tightening state with respect to the handpiece head portion of the lid body to which the C-ring is mounted in the present embodiment. FIG. 6 is an explanatory view showing a front view, a plan view, a bottom view, a left side view, a right side view, and a rear view of the lid body to which the C-ring is mounted in the present embodiment. FIG. 7 is a schematic explanatory view showing another example of the C ring, which is an elastic member in the present embodiment, and its arrangement. FIG. 8 is an exploded perspective view showing an O-ring according to a modified example of a lid screwed into the handpiece head portion of the dental handpiece according to the present embodiment and an elastic member loosely fitted into the first concave groove of the lid body. FIG. FIG. 9 is a partially enlarged cross-sectional view showing a handpiece head portion, a lid, and a C ring in a dental handpiece according to a modification of the present embodiment. FIG. 10 is an enlarged cross-sectional view showing a handpiece head portion, a lid, and a C-ring according to another modification in the dental handpiece according to the present embodiment. FIG. 11 is a plan view of a C-ring according to another modification shown in FIG.

The present invention provides a dental handpiece that can accurately prevent the lid that is screwed to the handpiece head portion from being loosened due to screw loosening based on a simple and inexpensive configuration that does not use a complicated locking mechanism or adhesive. In a dental handpiece comprising a cartridge housing that holds a cutting tool that is rotationally driven in a projecting state from the center portion of the lower end surface and is detachably held in a receiving area of the handpiece head portion. A male screw provided on the peripheral wall portion of the lid that covers the upper part of the lid and a female screw provided on the inner wall of the upper cylindrical portion of the handpiece head part, wherein the screw is detachably coupled, and the peripheral wall of the lid body Female screw insertion end provided on the inner wall of the upper end tubular portion of the handpiece head portion with a first concave groove that loosely fits the inner peripheral side of the ring-shaped elastic member in the male screw terminal provided in the portion When the lid body is screwed to the handpiece head portion, a second concave groove is provided which is disposed opposite to the first concave groove and accommodates the outer peripheral side of the ring-shaped elastic member. The ring-shaped elastic member that is displaced in conjunction with the lid body along with the loosening is configured to generate a contact resistance force by contact with the inner walls of the first and second concave grooves, and The inner periphery is realized by a configuration in which a counterbore portion having a downwardly inclined shape extending from the upper end to the vicinity of the upper end of the second concave groove is provided.

Hereinafter, a dental handpiece according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 to 5, the dental handpiece 1 according to the present embodiment includes an upper end cylindrical portion 3 (shown with cross-hatching) having a circular outer shape on the upper end side. An accommodation region 4 is formed in the range from the inside of the cylindrical portion 3 to the inside of the lower end, and the cutting tool 22 that is rotationally driven in the accommodation region 4 is in a projecting state downward from the center portion of the lower end surface and is attached and detached It has a handpiece head portion 2 configured to accommodate a cartridge housing 21 that can be held.

Then, in a state where the cartridge housing 21 is accommodated in the accommodating area 4 of the handpiece head portion 2, a substantially cylindrical lid body 11 whose upper end side is closed from above is screwed into the upper end cylindrical portion 3. By tightening, the cartridge housing 21 is integrally fixedly connected to the handpiece head portion 2 while shielding the upper portion thereof from the outside, and screwing of the lid 11 to the upper cylindrical portion 3 is released. By doing so, the cartridge housing 21 can be removed upward from the handpiece head portion 2.

That is, the lid body 11 includes a cylindrical peripheral wall portion 12, a cartridge housing holding disc portion 13 that is in contact with an upper end surface region 21 a of the cartridge housing 21 that is integrally formed inside the peripheral wall portion 12, and a cylinder. And an upper end closing disc portion 14 which is closely attached to the upper end opening of the peripheral wall portion 12 and completely closes the upper end opening.

The outer peripheral portion of the peripheral wall portion 12 of the lid body 11 is formed at a substantially intermediate position in a direction protruding from the upper end closing disc portion 14 and laterally in a tapered shape gradually increasing as the outer wall portion reaches the lower side. A projecting peripheral wall portion 12a is provided, and the lower surface of the projecting peripheral wall portion 12a is used as a flat contact step portion 12b. When the lid body 11 is screwed into the handpiece head portion 2 and tightened, the contact step The portion 12b is configured to be in pressure contact with the upper end surface of the upper cylindrical portion 3.

Further, the outer peripheral portion of the peripheral wall portion 12 in the lid body 11 is disposed on the lower side of the contact step portion 12b, and is formed of, for example, a stainless steel ring and has a radial expansion / contraction function. For example, a first concave groove 15 having a U-shaped cross section (or a reverse U-shaped cross section) is provided to loosely fit the inner peripheral side of the C-ring 17, and the circumferential wall portion 12 is formed immediately below the first concave groove 15. A male screw 16 reaching the protruding end is provided.

That is, the first concave groove 15 is provided at the male screw terminal portion of the male screw 16.

On the other hand, when the peripheral wall portion 12 of the lid body 11 is screwed into the handpiece head portion 2 and tightened on the inner wall of the upper end tubular portion 3 of the handpiece head portion 2 in the vicinity of the upper end thereof. For example, a second concave groove 5 having an inverted U-shaped cross section (or a U-shaped cross section) that is disposed opposite to the first concave groove 15 and accommodates the outer peripheral side of the C ring 17 is provided. A female screw 6 to be screwed with the male screw 16 is provided below the concave groove 5.

That is, the second concave groove 5 is provided at the female screw starting end portion of the female screw 6.

Further, a counterbore portion 7 having a downward inclined shape whose inner diameter is reduced from the upper end to the vicinity of the upper end of the second concave groove 5 is provided on the inner periphery of the upper end cylindrical portion 3.

A handpiece arm receiving portion 8 (shown with cross hatching) is provided on a part of the outer periphery of the upper cylindrical portion 3 in the handpiece head portion 2, and the handpiece arm receiving portion 8 is provided with a handpiece arm. The part 31 is configured to be integrally attached.

Further, as shown in FIG. 1, the handpiece arm receiving portion 8 has a screw hole 9 screwed downward from its upper surface in an arrangement located near the outer periphery of the upper cylindrical portion 3. By screwing and tightening a lid holding screw 10 in the shape of a countersunk into the hole 9, the outer periphery of the tapered head of the lid holding screw 10 is brought into contact with the projecting peripheral wall portion 12 a of the lid 11. The lid 11 is structured to be held down to the upper cylindrical portion 3 side in the handpiece head portion 2.

In addition, illustration is abbreviate | omitted about the whole structure of the dental handpiece 1 which concerns on a present Example. In FIG. 1, reference numeral 8 a denotes a screw-in guide piece arranged around the screw hole 9.

FIG. 6 shows a front view, a plan view, a bottom view, a left side view, a right side view, and a rear view of the lid body 11 in which the C ring 17 is loosely fitted in the dental handpiece 1 according to the present embodiment. .

Next, regarding the operation and effect of the dental handpiece 1 according to the present embodiment, the handpiece when the lid 11 is screwed into the handpiece head 2 and the lid 11 is loosened. The operation for preventing the head part 2 from falling off will be mainly described, and the cases will be described separately.

(Screwing operation of the lid 11 on the handpiece head 2)
First, after the cartridge housing 21 is accommodated in the accommodating area 4 of the handpiece head part 2, the male screw 16 of the lid 11 in which the C ring 17 is loosely fitted into the first concave groove 15 from above is inserted into the upper cylindrical part. 3 is screwed into the female screw 6 provided in 3 and tightened.

At this time, when the lid 11 is tightened with respect to the handpiece head part 2, the outer peripheral side of the C ring 17 abuts against the inclined wall surface of the counterbore part 7, and gradually decreases in diameter to temporarily form the first concave groove. 15 passes through the area of the spot facing 7.

Next, when the tightening of the lid 11 proceeds to a position where the first concave groove 15 and the second concave groove 5 face each other, the C ring 17 is released from restraint by the wall surface of the counterbore portion 7 and expands in diameter. The outer peripheral portion is in a state of being accommodated in the second concave groove 5.

As described above, in this embodiment, the counterbore portion 7 is provided, so that the C ring 17 loosely fitted in the first concave groove 15 of the lid body 11 can be fitted without any trouble during the screwing operation of the lid body 11. It is possible to smoothly enter the second concave groove 5.

In this state, the cartridge housing holding disc portion 13 is in close contact with the upper end surface region 21a of the cartridge housing 21, and the cartridge housing 21 is integrated into the handpiece head portion 2 while shielding the upper portion from the outside. Fixedly connected.

Further, the lid body 11 is screwed into the screw hole 9 and tightened to tighten the lid body 11 toward the upper cylindrical portion 3 side of the handpiece head portion 2. These states are shown in FIG.

(Operation of preventing the cap 11 from falling off from the handpiece head 2 when the lid 11 is loosened)
Next, the operation when the screw 11 is loosened due to some factor (for example, multiple use of the dental handpiece 1) in the lid 11 will be described.

After the male screw 16 of the lid body 11 and the female screw 6 are in a screw tightened state, when a screw loosening occurs between the male screw 16 and the female screw 6, along with this screw loosening, The cover 11 is gradually displaced from the state shown in FIG. 4A to the upper cylindrical portion 3 in the handpiece head portion 2 (that is, in the direction of dropping) as shown in FIG. 4B. To do.

At this time, the lower part of the C-ring 17 is pushed by the lower inner wall of the first concave groove 15 and tends to be displaced upward, while the upper part (outer peripheral side upper part) of the C-ring 17 is the upper part of the second concave groove 5. By contacting the upper inner wall, a contact resistance force for preventing the lid body 11 from falling off by the C ring 17 is generated, and further screw loosening can be prevented.

And if such a state is maintained, it becomes possible for the user to recognize and respond to the screw looseness due to the product noise and vibration due to the screw loosening before the lid 11 completely falls off. A major accident due to the complete removal of the lid 11 will not occur.

That is, in the dental handpiece 1 of this embodiment, the lid body is temporarily suppressed based on a simple and inexpensive structure in which the C-ring 17 is interposed between the first concave groove 15 and the second concave groove 5. Even if the screw 10 is forgotten to be attached or dropped, and the screw 11 of the lid 11 is loosened, the screw of the lid is further loosened by the contact resistance force in the loose state of the C-ring 17. If this condition is maintained, the user can detect the looseness of the lid due to the noise or vibration of the product due to the looseness of the lid. It becomes possible to prevent.

FIG. 7 employs a C ring 17A which is another example of the C ring 17 which is an elastic member in the present embodiment, and the C ring 17A is interposed between the first concave groove 15 and the second concave groove 5. Is shown.

The C ring 17A is made of, for example, stainless steel, and is formed into a C shape as a whole by forming a polygonal portion having an inner circumference in an arc shape and an outer circumference having six sides. It has the structure which has the corner | angular part 18 and exhibits an expansion / contraction function.

Then, the inner periphery of the C ring 17A is loosely fitted in the first concave groove 15, and each corner 18 on the outer periphery is easily accommodated in the second concave groove 5 when the lid body 11 is screwed. In addition, each corner portion 18 (a linear portion forming the corner portion 18 of the C ring 17A) is reliably brought into contact with the inner peripheral portion of the second concave groove 5.

By adopting such a C-ring 17A, it is possible to exert the same action and effect as the case of the C-ring 17 described above, and the C-ring 17A is located at the center of the upper cylindrical portion 3. Even if the lid body 11 is loosened, the C-ring 17A is not easily detached from the second concave groove 5, and the lid body 11 is in a loosened state. It is possible to accurately prevent the complete dropout.

In the C ring 17A, the outer periphery is formed into a C shape by forming a polygonal portion having six sides, and the outer periphery has a total of seven corners 18 equidistant from the center. However, the present invention is not limited to this, and the number of outer peripheral sides and the number of corner portions 18 can be variously set.
For example, a polygonal portion having two sides on the outer periphery is formed to form a C shape as a whole, and the outer periphery has a total of three corners 18 equidistant from the center, or has four sides on the outer periphery. Various modifications are possible, such as forming a polygonal portion to form a C shape as a whole and having a total of five corners 18 equidistant from the center on the outer periphery. The same effect can be exhibited. The number of the corner portions 18 is preferably at least three in order to exhibit the effect of preventing the lid body 11 from falling off.

FIG. 8 relates to a modified example of the lid 11 screwed into the handpiece head portion 2 in the dental handpiece 1 according to the present embodiment and the elastic member loosely fitted in the first concave groove 15 of the lid 11. For example, an O-ring 19 made of stainless steel and having an expansion / contraction function is shown.

By adopting such an O-ring 19, it is possible to exhibit the same operations and effects as those of the C-ring 17 described above.

Also in the case of the O-ring 19, although not shown, the outer peripheral shape can be various forms similar to the case of the C-ring 17A.

FIG. 9 shows the handpiece head portion 2, the lid 11 and the C ring 17 in a dental handpiece 1A according to a modification of the present embodiment.

In addition, in the dental handpiece 1A shown in FIG. 9, the same code | symbol is attached | subjected to the same element as the case of the dental handpiece 1 which concerns on the Example mentioned above, and the detailed description is abbreviate | omitted.

The basic configuration of the dental handpiece 1A shown in FIG. 9 is the same as that of the dental handpiece 1 according to the embodiment. However, the screwing guide piece 8a and the screw hole 9 provided in the handpiece arm receiving portion 8 are the same. In addition, the lid holding screw 10 is omitted.

Also with the dental handpiece 1A shown in FIG. 9, the screw of the C ring 17 is based on a simple and inexpensive structure in which the C ring 17 is interposed between the first concave groove 15 and the second concave groove 5. The contact resistance force in the loose state accurately prevents the cover body 11 from completely falling out even if the cover body 11 is in the screw loose state while eliminating the need for a screw loosening prevention structure such as an adhesive as in the conventional example. can do.

Also in the dental handpiece 1A shown in FIG. 9, the C ring 17A or the O ring 19 is adopted instead of the C ring 17, and the same effects as those described above can be exhibited.

Furthermore, the above-mentioned C-rings 17, 17A and O-ring 19 are made of stainless steel, so that they can exhibit excellent durability and can be used for autoclaves, or dental handpieces 1 or dental. A handpiece 1A can be provided.

The above-described C-ring 17 can be formed by bending a spring material such as a stainless steel wire, and the shape thereof is not limited to a circular shape, and may be a polygonal shape.

The above-described C-ring 17A can also be formed by processing a spring material such as a stainless steel wire, and in this case, not only the outer peripheral side but also the inner peripheral side can have a polygonal shape. Further, the corner portion 18 may have an R shape.

The O-ring 19 can also have the same configuration as that of the C ring 17 or the C ring 17A using the stainless steel wire as described above.

Next, with reference to FIG. 10, FIG. 11, the C-ring 17B which concerns on the handpiece head part 2, the cover body 11, and another modification in the dental handpiece 1 of a present Example is demonstrated.

The dental handpiece 1 shown in FIG. 10 has the same configuration as the dental handpiece 1 shown in FIGS. 1 and 3, but a C ring 17 </ b> B that is an elastic member according to another modification is attached to the lid body 11. Similar to the case described above, the contact resistance force in the loosened state of the lid 11 of the C ring 17B is arranged between the first concave groove 15 and the second concave groove 5 of the handpiece head portion 2. Thus, it is possible to accurately prevent the lid body 11 from falling off even if the lid body 11 is in a screw loosened state, while eliminating the need for a screw loosening prevention structure such as an adhesive as in the conventional example. It is a feature.

As shown in FIGS. 10 and 11, the C ring 17 </ b> B is formed by bending a stainless steel wire 23 having elasticity, for example, to have a substantially C shape as a whole and having a function of expanding and contracting, and the stainless steel wire 23. A plurality of bent bulging protrusions 24 that bulge outward are provided in a separate arrangement (for example, three separate arrangements), and this C-ring 17B is connected to the first concave groove 15 and the second concave shape. When arranged between the groove 5 and the groove 5, the outer peripheral side of each of the bulging protrusions 24 is configured to come into contact with the wall surface defining the second concave groove 5, which is the target portion, by surface contact.

In addition, each portion of the C ring 17B that bulges to the outermost side of each bending bulge protrusion 24 is formed to be equidistant from the center of the C ring 17B. When arranged between the first concave groove 15 of the lid 11 and the second concave groove 5 of the handpiece head portion 2, the center of the upper cylindrical portion 3 and the center of the C ring 17B are matched. It is configured.

As described above, the outer periphery of the C ring 17B is not in full contact with the wall surface defining the second concave groove 5, but the outer peripheral side of each bending bulge protrusion 24 is in contact with each bend. The outer peripheral side other than the bulging protrusion 24 is configured not to contact but to contact in a discontinuous contact state in which a gap 25 is formed.

At this time, the inner peripheral portion of the C ring 17B is inevitably contacted with the wall surface of the first concave groove 15 in a discontinuous contact state in which the inner peripheral portion is not in full contact but forms a gap 25. Get in touch.

By adopting such a C-ring 17B, the C-ring 17B is evenly arranged with respect to the center of the upper cylindrical portion 3 as in the case of the C-ring 17 described above, and the lid Even if the body 11 is loosened, the C-ring 17B is difficult to come off from the second concave groove 5, and even if the lid 11 is loosened, its complete drop-off can be prevented accurately.

Of course, the dental handpiece 1A shown in FIG. 9 may be configured to employ the C-ring 17B.

Although not shown, it is also possible to employ an O-ring that employs a configuration similar to that of the C-ring 17B as shown in FIGS.

The lid drop-off prevention mechanism using the ring-shaped elastic member in the dental handpiece of the present invention is a cartridge-type lid for various dental handpieces having a lid fixed to the handpiece head portion by screw connection. The present invention can be widely applied to applications for preventing dropout due to screw loosening, and further, for preventing mechanical dropout due to screw loosening in various mechanical parts that are interconnected by screw connection.

DESCRIPTION OF SYMBOLS 1 Dental handpiece 1A Dental handpiece 2 Handpiece head part 3 Upper end cylindrical part 4 Storage area 5 Second concave groove 6 Female screw 7 Counterbore part 8 Handpiece arm receiving part 8a Screw-in guide piece 9 Screw hole 10 Lid body holding screw 11 Lid body 12 Peripheral wall part 12a Projecting peripheral wall part 12b Abutting step part 13 Cartridge housing holding disk part 14 Upper end closing disk part 15 First concave groove 16 Male thread 17 C ring

17A C ring

17B C Ring 18 Corner portion 19 O-ring 21 Cartridge housing 21a Upper end surface region 22 Cutting tool 23 Stainless steel wire 24 Bending bulge 25 Clearance 31 Handpiece arm

Claims

In a dental handpiece including a cartridge housing that holds a cutting tool that is rotationally driven in a projecting state from the central portion of the lower end surface and is detachably held in an accommodation region of the handpiece head portion.
The male screw of the lid that covers the upper part of the cartridge housing and the female screw of the handpiece head part are detachable threaded couplings,
A first concave groove that loosely fits the inner peripheral side of the ring-shaped elastic member to a male screw terminal provided in the peripheral wall of the lid is formed in the female screw insertion end provided in the handpiece head. When the lid is screwed to the handpiece head portion, a second concave groove is provided that is disposed opposite to the first concave groove and accommodates the outer peripheral side of the ring-shaped elastic member;
The ring-shaped elastic member that is displaced in conjunction with the lid body with the looseness of the lid body is configured to generate a contact resistance force due to contact with the inner walls of the first and second concave grooves. A dental handpiece.
In a dental handpiece including a cartridge housing that holds a cutting tool that is rotationally driven in a projecting state from the central portion of the lower end surface and is detachably held in an accommodation region of the handpiece head portion.
A male screw provided on the peripheral wall portion of the lid that covers the upper portion of the cartridge housing and a female screw provided on the inner wall of the upper cylindrical portion of the handpiece head portion are detachable threaded couplings,
A female in which a first concave groove for loosely fitting the inner peripheral side of the ring-shaped elastic member is provided on the inner wall of the upper end tubular portion of the handpiece head portion at the end of the male screw provided on the peripheral wall portion of the lid. When the lid is screwed to the handpiece head portion at the screw insertion end portion, a second concave groove is provided which is disposed opposite to the first concave groove and accommodates the outer peripheral side of the ring-shaped elastic member,
The ring-shaped elastic member that is displaced in conjunction with the screw of the lid is loosened, and a contact resistance force is generated by contact with the inner walls of the first and second concave grooves.
A dental handpiece characterized in that a counterbore portion having a downwardly inclined shape extending from the upper end thereof to the vicinity of the upper end of the second concave groove is provided on the inner periphery of the upper end cylindrical portion.
In a dental handpiece including a cartridge housing that holds a cutting tool that is rotationally driven in a projecting state from the central portion of the lower end surface and is detachably held in an accommodation region of the handpiece head portion.
A male screw provided on the peripheral wall portion of the lid that covers the upper portion of the cartridge housing and a female screw provided on the inner wall of the upper cylindrical portion of the handpiece head portion are detachable threaded couplings,
A first concave groove for loosely fitting the inner peripheral side of the ring-shaped elastic member to the male screw terminal provided on the peripheral wall of the lid;
The ring-shaped elastic member is arranged to face the first concave groove when the lid body is screwed to the handpiece head portion at the female screw insertion end portion provided on the inner wall of the upper end tubular portion of the handpiece head portion. Providing a second concave groove for accommodating the outer peripheral side of
The ring-shaped elastic member that is displaced in conjunction with the screw of the lid is loosened, and a contact resistance force is generated by contact with the inner walls of the first and second concave grooves.
Provided on the inner periphery of the upper cylindrical portion is a counterbore portion having a downward inclined shape extending from the upper end to the vicinity of the upper end of the second concave groove,
A lid body restrainer that is screwed into a handpiece arm receiving portion connected to the outer side of the upper end tubular portion of the handpiece head portion, and the head outer periphery is brought into contact with the peripheral wall portion of the lid body and restrained toward the upper end tubular portion side. A dental handpiece provided with a screw.
The dental handpiece according to any one of claims 1 to 3, wherein the ring-shaped elastic member is a C ring or an O ring.
The elastic member made of the C ring or the O ring is formed in a shape having a substantially polygonal outer peripheral portion and a plurality of corner portions, and an inner peripheral wall of the second concave groove of the handpiece head portion and each corner portion. The dental handpiece according to claim 1, wherein the dental handpiece is in contact with the dental handpiece.
The dental handpiece according to any one of claims 1 to 5, wherein a material of the elastic member made of the C ring or the O ring is stainless steel.
The elastic member made of the C ring or O ring is formed by bending a stainless steel wire having elasticity to have a shape having an expansion / contraction function as a whole, and a plurality of bending expansions bulging outward with respect to the stainless steel wire. The protruding protrusion is provided in a separate arrangement, and the outer peripheral side of each bent bulge protrusion is configured to abut on the wall surface defining the concave groove as the target portion by surface contact with the discontinuous separation arrangement. Item 4. The dental handpiece according to any one of Items 1 to 3.