JPH0416659Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention mainly relates to the chuck structure of a rotary cutting tool such as a dental handpiece.

(Prior Art) In dental treatment using a handpiece, the cutting bur is frequently replaced during treatment depending on the type of treatment. Therefore, in this type of dental handpiece, the cutting bur is detachably attached via chuck means. Such chuck means include a friction chuck that elastically deforms using an elastic body such as resin, rubber, a coil spring, or a plate spring to elastically grip the cutting bar, and a chuck member made of metal or the like and a chuck case (rotation drive shaft). A collet chuck or the like is used that clamps and grips the cutting bar by applying pressure in the centripetal direction by pressure contact between the tapered surfaces of the bar.

(Problems to be Solved by the Invention) However, the rotary cutting tools having the chuck means described above each have the following problems. In other words, the friction chuck has the advantage that the cutting bar hardly ever slips out, but on the other hand, the cutting bar undergoes elastic deformation when it is attached and detached, and this is compounded by the heat load during sterilization, so it deteriorates over time. As a result, the holding force of the cutting bar decreases, resulting in a lack of durability. Further, since the bar is held by forcibly elastically deforming the chuck, it is troublesome that a special tool for attaching and detaching the bar must be used when attaching and detaching the chuck. On the other hand, in the case of a collect chuck, it is held by metal-to-metal pressure welding, so it has excellent heat resistance and is durable, but the contact area that holds the cutting bar is small, so the center runout of the cutting bar is large, and the chuck is held under strong force. Since the chuck must be tightened with a screw, it is difficult to operate, and there is also the risk that the chuck may loosen during rotation and the cutting bar may fall out. Furthermore, if the chuck was tightened without a cutting bar attached, the chuck would become excessively deformed and would not restore its original shape, making it unusable.

The present invention was made to solve the above problems, and by using both a friction chuck and a collection chuck, the drawbacks of both are offset, and a new rotary cutting tool chuck with excellent durability and operability is created. It is intended to provide structure.

(Means for Solving the Problems) The configuration of the present invention for achieving the above object will be explained based on the attached embodiment drawings. Fig. 1 is a longitudinal cross-sectional view of the head portion of a dental handpiece to which the present invention is applied, Fig. 2 is an exploded perspective view of the chuck portion of the same embodiment, and Fig. 3 is the same as Fig. 1 of another embodiment. Similar figure, 4th
The figure is a similar view of another embodiment, FIG. 5 is an exploded perspective view of the pressure fluid introduction part in the same embodiment, FIG. 6 is an overall view of the handpiece of the same embodiment, and FIG. 7 is the same embodiment. Fig. 8 is a timing chart of the same, Fig. 9 is a pipe line configuration diagram of the same embodiment, and Fig. 10 is a diagram of the operation control circuit of the same embodiment.
The figures are similar views of other embodiments. That is, the chuck structure of a rotary cutting tool of the present invention is a chuck structure of a rotary cutting tool in which a cutting bar 4 is held on a rotary drive shaft 2 in a tip casing 1 via a chuck means 3. 3 is a metal collect chuck 31 that is fitted into the cylindrical rotation drive shaft 2, and the cutting bar 4 is elastically gripped by the centripetal pressing force of the collect chuck 31 that is installed inside the collect chuck 31 and is inserted into the cylindrical rotation drive shaft 2. It is characterized by consisting of a friction chuck 32.

The friction chuck 32 is preferably made of a heat-resistant elastic material such as hard fluorine rubber, heat-resistant urethane rubber, or Teflon resin that can withstand high-temperature sterilization and gas sterilization, thereby preventing secondary infections such as hepatitis B and AIDS. Infection will be prevented.

(Function) In the chuck structure configured as described above, the collection chuck 31 of the chuck means 3 receives a pressing force in the centripetal direction when it is fitted onto the rotational drive shaft 2. This pressing force is transmitted to the friction chuck 32 mounted inside the collection chuck 31, and is further applied to the peripheral body of the cutting bar 4 inserted through the friction chuck 32, thereby acting as a gripping force. Therefore, the collet chuck 31 is not directly involved in the part where the cutting bar 4 is substantially gripped, and as a result, there is a risk of core runout, strong clamping force, and medical accidents caused by the cutting bar slipping out due to metal-to-metal pressure contact, as in conventional collet chucks. Such problems are not caused. In addition, since the friction chuck 32 elastically grips the cutting bar 4 by receiving the centripetal pressing force from the collection chuck 31 behind it, the friction chuck 32 itself will not deteriorate over time due to heat load due to sterilization, etc. Even if there is a problem, correct check 3
Since the pressing force of 1 covers the entire length, a constant gripping force necessary for gripping the cutting bar 4 is guaranteed. Moreover, in the case of such a gripping mechanism, the inner diameter of the friction chuck 32 can be approximated to the outer diameter of the cutting bar 4 (by the way, in the case of a conventional friction chuck, the cutting bar can be press-fitted and the chuck can be opened by pressing the cutting bar into the chuck). Since it grips it by elastically deforming itself, its inner diameter is considerably smaller than the outer diameter of the cutting bar.) When attaching and detaching the cutting bar, the cutting bar can be easily inserted and removed by hand. Moreover, if the inner diameter of the friction chuck 32 is desirably made slightly smaller than the outer diameter of the cutting bar, the cutting bar 4 can be inserted and removed by hand, and at the same time, unnecessary dropping of the cutting bar 4 can be prevented.

(Example) Next, an example will be described.

(Embodiment 1) The embodiment shown in FIGS. 1 and 2 shows an example of application to a dental air turbine handpiece, and a cylindrical rotary drive shaft having an impeller 21 in the tip casing, that is, the head portion 1. 2 is rotatably installed inside via bearings 5, 5. The drive shaft 2 also serves as a chuck case, and a chuck means 3 is fitted and integrated into the cylinder thereof, and the cutting bar 4 gripped by the chuck means 3 is connected to a turbine air The compressed air supplied from the supply pipe 20 acts on the impeller 21 so that the impeller rotates integrally with the impeller 21, and is provided for dental treatment.

The chuck means 3 includes a collect chuck 31 made of metal or the like, which has a tapered part 311 whose outer diameter on the distal side is gradually tapered, and a plurality of slits 312 cut out from the distal end along the axial direction, and the taper part 311. It consists of a friction chuck 32 fitted into the inner surface of the collector chuck 21, a compression spring 33 fitted around the rear end of the collector chuck 21, and a spring receiver bushing 34 screwed onto the rear end surface of the collector chuck 31. . On the other hand, a tapered portion 22 whose inner diameter is tapered in advance is formed on the inner surface of the tip of the drive shaft 2, so that when the chuck means 3 is inserted into the drive shaft 2, the tapered portions 311 and 22 of the two correspond to each other. is being done. And check means 3
is inserted into the drive shaft 2, a compression spring 33 is interposed between the rear end surface of the drive shaft 2 and the flange 341 of the bush 34, and when the bush 34 is screwed onto the rear end of the collector chuck 31, compression occurs. The chuck means 3 is elastically biased rearward by the restoring elasticity of the spring 33. Due to this elastic bias, the tapered portions 311 and 22 are brought into pressure contact with each other, and the drive shaft 2
and the chuck means 3 are integrated, and the taper portion 311 of the collection chuck 31 is deformed in the centripetal direction, and a centripetal pressing force is applied to the friction chuck 32 attached to the inner surface thereof. Therefore, if the cutting bar 4 is inserted into the inner cylinder of the chuck means 3, the cutting bar 4 will be held integrally by the chuck means 3 by this pressing force. In the figure, reference numeral 35 denotes a front guide made of hard metal, which together with the rear guide part 314 is formed to be slightly larger than the outer diameter of the cutting bar 4 to prevent the cutting bar 4 from swinging around during rotation.

In the state where the cutting bar 4 is gripped by the chuck means 3 as described above, the collection chuck 31
When the rear end surface is pressed forward against the elasticity of the compression spring 33, the collection chuck 31 moves forward, and the mutual pressure between the tapered portions 311 and 22 is relaxed, thereby reducing the gripping force. As a result, the cutting bar 4 can be easily extracted by hand. The chuck means 3 is released by the push means described below.

That is, a bearing holding case 11 is screwed onto the rear end surface of the head portion 1, a cap 12 is elastically mounted on the holding case 11 via a compression spring 13, and a projection 121 is provided approximately at the center of the inner surface of the cap 12.
is provided protrudingly so as to face the back surface of the bush 34. The cap 12 is normally urged backward by the elasticity of the compression spring 13, and when the cutting bar 4 is to be gripped and released by the chuck means 3, the cap 12 is pushed from the back against the elasticity of the compression spring 13. If you push it with your fingers, place the protrusion 121 against the bush 34, and push it further against the elasticity of the compression spring 33,
As described above, the grip of the chuck means 3 is released and the cutting bar 4 can be extracted. When the cutting bar 4 is replaced in this state and the pressing of the cap 12 is stopped, the cutting bar 4 is gripped and integrated with the chuck means 3 by the opposite action to that described above.

In addition, in the illustrated example, the outer diameter of the rear end portion 313 of the collector chuck 31 (the portion where the compression spring 33 is fitted) is smaller than the outer diameter of the rear guide 314, and the boundary between the two different diameter portions is a reduced diameter step. 315,
On the other hand, an inward flange 22 is formed at the rear end of the drive shaft 2, and the abutment of the diameter-reducing step 315 against the inward flange 22 prevents the collection chuck 31 from moving back excessively. Therefore, the tip of the collet chuck 31 is not excessively deformed, and in the past, when the collet chuck was clamped without a cutting bar attached, it was often irreversibly deformed and became unusable. Such troubles can be prevented by the above configuration.

(Example 2) The example shown in FIG. 3 also shows an example of application to a dental air turbine handpiece, but the configuration of the push means is different from the above example.
The chuck part is almost the same as the above example, so
Here, common parts will be given the same reference numerals and a description thereof will be omitted, and the pushing means will be described in detail.

A cap retaining ring 14 is screwed onto the back of the bearing retaining case 11 similar to the above, and the retaining ring 14 locks the same cap 12 as described above, and a wave washer 15 is loaded between the cap 12 and the retaining case 11. , cap 12
is always elastically biased backwards. In this case as well, if the cap 12 is pressed against the elasticity of the wave washer 15, the grip on the chuck means 3 is released, as described above, but a cap retaining ring is placed between the bearing retaining case 11 and the cap 12. An added advantage is that the cap 12 can be easily attached by interposing the cap 14.

(Embodiment 3) In the embodiment shown in FIGS. 4 to 8, the head portion 1
This shows an example in which the chuck means 3 is gripped and released by compressed air introduced into the chuck, but since the chuck portion here is the same as in the above embodiment, the same reference numerals are given to the common parts and the details thereof will be explained below. The explanation will be omitted and the compressed air introduction section will be explained in detail.

A compressed air supply line 6 is installed inside the handpiece body 10, and the supply line 6 reaches a threaded part 16 between the head part 1 and the cap 12, and this threaded part 16 has a through hole 161. The through hole 161 is opened and compressed air is introduced into the head portion 1 through the through hole 161. A cylindrical air bypass collar 61 is fitted into the cap 12, and a circumferential groove 611 is recessed in the collar 61 at a position corresponding to the through hole 161, and communicates with the circumferential groove 611. Passing grooves 612..., 613...
are formed on its circumferential body and back surface. An air supply hole 614 is provided at the center of the back of the collar 61, and the compressed air from the supply pipe 6 is passed through the through hole 16.
1. It is introduced into the collar 61 through the circumferential groove 611, the through grooves 612..., 613..., and the air supply hole 614.
A push plate 62 is airtightly fitted into the collar 61 through an O-ring 622 so as to be slidable back and forth, and is moved forward by the action of compressed air introduced into the back surface of the collar 61, and is moved forward to the center of the front surface of the push plate 62. The chuck means 3 is pressed by the protrusion 621 protruding therefrom, thereby releasing the grip on the cutting bar 4. In addition, the reference numeral 16 in the figure
Reference numeral 2, 162 denotes O-rings placed around the front and back of the threaded portion 16 to prevent compressed air from entering the head portion 1. In the case of this embodiment, it is possible to provide the compressed air supply line 6 alone, but it is also possible to use it in common with the working medium line for dental treatment through an appropriate changeover switch (not shown). .

FIG. 6 shows an overall view of a dental handpiece in which the same embodiment is adopted, and a touch switch 63 for turning on/off the introduction of compressed air is provided near the head portion 1 of the main body 10. If the touch switch 64 is provided in such a position, the operator can replace the cutting bar 4 with a simple operation of the index finger without changing the handpiece from the pen grip (the grip state during treatment).

FIG. 7 shows an example of an operational circuit diagram applied to the same embodiment. Solenoid valve 7 in the diagram
is a three-way valve installed in the middle of the piping from the compressor (not shown), and the foot switch 71
If you step on the button to turn it ON, it will open to the air turbine side, and if you turn it OFF, it will open to the chuck operation side. A solenoid valve 64 for chuck operation is disposed in the middle of the chuck operation side piping, and opens after a time set by a timer 72 has elapsed after the foot switch 71 is turned off. When the touch switch 63 is operated in this state, compressed air is introduced into the head 1 as described above, and the grip of the cutting bar 4 on the chuck means 3 is released, allowing it to be removed. According to such an operating circuit, even if the touch switch 63 is operated by mistake while the cutting bar 4 is rotating, the cutting bar 4 will not be released from the grip, which is safe, and is preferably employed. Figure 8 shows
This timing chart shows that the chuck is closed (i.e., gripped) during turbine operation (ON state), and can be released after a predetermined period of time has elapsed after the turbine is turned OFF. In this case, chuck OPEN means that the solenoid valve 64 for chuck operation is opened, and therefore, the chuck will not be released unless the touch switch 63 is operated.

FIG. 9 shows a diagram of the pipe line configuration of the same embodiment. In the figure, the three-way valve 7 is opened and closed by the operation signal of the foot switch, and when the foot switch is turned on, the air turbine side is opened, and the pressure reducing valve 73 and the throttle valve 7 are opened.
Compressed air is supplied to the air turbine supply pipe 20 through the air turbine supply line 20 through the air turbine supply pipe 20 and the like. On the other hand, when the foot switch is turned OFF, the air turbine side of the three-way valve 7 is closed and the chuck side is opened. When the touch switch is turned on after the time set by the timer, the chuck operating solenoid valve 64 opens, and compressed air is supplied to the chuck releasing compressed air supply line 6.

FIG. 10 shows another embodiment of the pipe line configuration diagram, in which the solenoid valve 75 is opened and closed by the ON/OFF operation of the foot switch, and when the valve 75 is open, air is compressed into the air turbine supply pipe 20 as described above. Air is supplied. In addition, the solenoid valve 64 for chuck operation is used to turn ON/OFF the touch switch.
It is opened and closed by operation, but remains closed while the valve 75 is open and during the timer setting time, and then when the touch switch is turned on, it opens and compressed air is supplied to the compressed air supply line 6 for chuck release. In addition, if the structure is such that the chuck is in a gripping state when air is being supplied and is released when the air supply is stopped, contrary to the above, when the valve 75 is open, It is also possible to maintain the valve 64 open and then close the valve 64 when the touch switch is turned on. Furthermore, it is obvious that the pressure source in FIGS. 9 and 10 is not limited to compressed air.

In the above embodiment, the cutting bar 4 is released by sliding the chuck means 3 back and forth by the push means, but the chuck means 3 is screwed onto the drive shaft 2 from the outside with a tool and moved back and forth. The chuck means 3 is designed to attach and detach the cutting bar by sliding it, or the relationship between the tapered portions 311 and 22 shown in the figure is reversed and the chuck means 3 is tapered in a progressively closing shape.
It is also applicable to a device in which the drive shaft 2 and the drive shaft 2 are clamped together. It is also possible to form the front guide 35 integrally with the drive shaft 2 or the collection chuck 31. Furthermore, in the above embodiment, a substantially cylindrical elastic body is shown as the friction chuck 32;
These include O-ring-shaped ones with a circular cross section, and ones formed so that they are discontinuous in the circumferential direction, such as by making slits in the axial direction. Further, in the embodiment, the case where the drive shaft 2 is rotatably held by the bearings 5 is shown, but the case where the drive shaft 2 is held by an air bearing is not excluded. In addition, in the illustrated example, a dental air turbine handpiece is taken as an example, but similar effects can be obtained if applied to a micromotor-driven or straight type handpiece, or even a rotary cutting tool for general machining.
It goes without saying that other changes may be made without departing from the scope of the present invention.

(Effect of the invention) As described above, in the chuck structure of the rotary cutting tool of the present invention, the chuck means 3 consists of a collection chuck 31 made of metal or the like and a friction chuck 32 mounted inside the collection chuck 31.
Since the cutting bar 4 is gripped by the friction chuck 32 which obtains the centripetal pressing force when press-fitting the cutting bar 4 into the drive shaft 2, the collector chuck 31 is not directly involved in gripping the bar 4, and therefore the metal Concerns about core run-out and the risk of the cutting bar 4 coming off due to pressure contact between the two bars are significantly reduced, and the operability is improved since a very strong force is not required for tightening. In addition, as mentioned above, the friction chuck 32 grips the cutting bar 4 by obtaining the centripetal pressing force of the collection chuck 31 behind it, so it does not undergo large elastic deformation of itself as in the conventional case, and therefore, it is not frequently deformed. Even if the cutting bar 4 is replaced, its degree of deterioration is reduced. Furthermore, when the above-mentioned pressing force is released, the gripping force of the friction chuck 32 itself is almost negligible, so that no separate tool is required to insert or remove the cutting bar 4, and the cutting bar 4 can be replaced very easily. As described above, the present invention offsets the drawbacks of the conventional collection chuck and friction chuck and combines only their advantages, making it highly functional and extremely valuable.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the head portion of a dental handpiece to which the present invention is applied, Fig. 2 is an exploded perspective view of the chuck portion of the same embodiment, and Fig. 3 is the same as Fig. 1 of another embodiment. 4 is a similar view of still another embodiment, FIG. 5 is an exploded perspective view of the pressure fluid introduction part in the same embodiment, FIG. 6 is an overall view of the handpiece of the same embodiment, and FIG. The figure is an operation control circuit diagram of the same embodiment, No. 8
9 is a diagram showing the same timing chart, FIG. 9 is a diagram showing the pipe line configuration of the same embodiment, and FIG. 10 is a similar diagram of another embodiment. Explanation of symbols: 1...Tip casing, 2...Rotation drive shaft, 3...Chuck means, 31...Collection chuck, 32...Friction chuck, 4
...Cutting bar.

Claims (1)

[Scope of utility model registration request] In the chuck structure of a rotary cutting tool in which a cutting bar 4 is held on a rotary drive shaft 2 in a tip casing 1 via a chuck means 3, the chuck means 3 is fitted into the cylindrical rotary drive shaft 2. Rotary cutting characterized in that it is comprised of a collector chuck 31, which is fitted in the collet chuck 31, and a friction chuck 32, which is mounted in the collet chuck 31 and elastically grips the cutting bar 4 by the pressing force in the centripetal direction of the collet chuck 31 when the collet chuck 31 is inserted. Tool chuck structure.