JPS6015538Y2 - Chuck for dental treatment instruments - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a chuck for dental treatment instruments.

Conventionally, a dental treatment instrument, for example, a dental air turbine, is configured as shown in FIG.

In FIG. 1, 1 is a turbine head, 2 is a cylindrical rotating shaft that is rotatably supported inside the turbine head 1 via a bearing 3, and 4 is an arch-shaped concave outer circumferential wall. A pressing protrusion 4a is provided on the inner circumferential wall of the central part, which has a thinner wall than the wall of the
This is a chuck in which three or four slotted grooves in the axial direction are cut in the pressing protrusion 4a.

The inner diameter of both ends of the inner peripheral wall of this chuck 4 is equal to or slightly larger than the diameter of the shank 5a of the cutting tool 5, and the inner diameter of the inner peripheral wall of the pressing protrusion 4a of the chuck 4 is smaller than the diameter of the shank 5a of the cutting tool 5. It is.

6 is a burst collar fixed to one end of the rotating shaft 2 into which the chuck 4 is press-fitted, and 7 is the chuck 4 which is press-fitted inside the rotating shaft 2.
This par checker 7 is a ring-shaped par checker having an inner diameter equal to the maximum diameter of the shank 5a of the cutting tool 5 that can be inserted into the cutter 5. This par checker 7 is fixed to the other end of the rotating shaft 2 into which the chuck 4 is press-fitted.

Reference numeral 8 denotes a plurality of turbine blades provided on the outer peripheral wall of the rotating shaft 2.

In the conventional example configured in this way, the shank 5 of the cutting tool 5
When a is press-fitted into the chuck 4, the pressing projections 4a are displaced in the radial direction, elastic deformation occurs in the center of the chuck 4, and the shank 5a is gripped by the pressing projections 4a.

However, when the chuck 4 rotates at a speed of 350,000 to 450,000 revolutions per minute when cutting teeth, etc., centrifugal force acts on the pressing projections 4a, and the gripping force of the pressing projections 4a decreases by the centrifugal force. Moreover, when the inner circumferential wall surface of the pressing projection 4a, which has a small area for transmitting gripping force to the shank 5a, wears out, the gripping force of the pressing projection 4a decreases significantly.

Furthermore, a pressing protrusion 4a protruding from the inner circumferential wall surface of the chuck 4
Since the shank 5a has to be press-fitted into the chuck 4, it is difficult to insert the shank 5a into the chuck 4, and the cutting tool 5
This has the drawback that excessive force is applied to the blade, causing frequent breakage of the cutting tool 5.

The present invention provides a chuck for dental treatment instruments that applies the principle of leverage in order to eliminate the drawbacks of the above-mentioned conventional examples.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which the same reference numerals as in FIG. A ring-shaped protrusion 9a is provided on the cylindrical surface, and four slotted grooves in the axial direction are formed on the circumferential wall of the cylinder between the front end of the cylinder and the protrusion 9a and between the rear end and the protrusion 9a, except for the protrusion 9a. This is a chuck that has been cut into four chuck segments 9b (see FIG. 2C).

The inner diameter of the inner circumferential wall surface from the front end of this chuck 9 to the protrusion 9a is equal to or slightly larger than the diameter of the shank 5a of the cutting tool 5, and the inner diameter of the inner circumferential wall surface from the protrusion 9a to the rear end of the chuck 9 is: It is gradually made smaller so that the inner diameter of the inner circumferential wall surface at the rear end becomes smaller than the diameter of the shank 5a of the cutting tool 5 (see FIG. 2).

In this embodiment configured in this way, when the chuck 9 is press-fitted into the rotating shaft 2 with the front end of the chuck 9 and the hole of the par checker 7 facing each other, the outer peripheral wall surface of the protrusion 9a is aligned with the rotating shaft 2. Although the chuck segment 9b is in pressure contact with the inner circumferential wall surface, the outer circumferential wall surface of the chuck segment 9b is separated from the inner circumferential wall surface of the rotating shaft 2 (see FIG. 2).

Therefore, when the shank 5a of the cutting tool 5 is press-fitted into the chuck 9 mounted inside the rotating shaft 2 (see FIG. 2C), the rear end of each chuck segment 9b of the chuck 9 will be
Since the tip of each chuck segment 9b tends to rotate in the direction of arrow B around the protrusion 9a (see FIG. 2d).

However, with the protrusion 9a fixed, the inner circumferential wall surface of the tip of each chuck segment 9b abuts the outer circumferential wall surface of the shank 5a, preventing the tip of each chuck segment 9b from rotating in the direction of arrow B. As a result, elastic deformation occurs in the chuck segments 9b around the projections 9a, and the inner circumferential wall surface of each chuck segment 9b comes into pressure contact with the outer circumferential wall surface of the shank 5a (see FIG. 2C).

That is, the shank 5a press-fitted into the chuck 9 is gripped by the chuck 9.

Next, when the chuck 9 is rotated at high speed with the chuck 9 gripping the shank 5a, each chuck segment 9
Centrifugal forces C and D act on the front and rear ends of chuck segment 9b, respectively, and the gripping force of each chuck segment 9b is weakened by centrifugal forces C and D (see FIG. 2d).

By the way, the protrusion 9 from the front end of each chuck segment) 9b
Since the mass up to a is smaller than the mass from the rear end of each chuck segment 9b to the protrusion 9a, the centrifugal force C is smaller than the centrifugal force R.

Therefore, a force equal to the difference between centrifugal forces C and D is applied to the rear end of each chuck segment 9b supported by the protrusion 9a in the direction of arrow A, and the front end of each chuck segment 9b pivots around the protrusion 9a. Since the chuck segment 9b rotates in the direction of arrow B, the gripping force at the front end of each chuck segment 9b becomes stronger.

As a result, when the chuck 9 is rotating at high speed, the sum of the gripping forces applied from each chuck segment 9b to the shank 5a is equal to the total gripping force applied from each chuck segment 9b to the shank 5a when the chuck 9 is stopped. equal to or greater than the grip force.

In addition, the thickness of the front end of each chuck segment 9b is made thinner,
If the thickness of the rear end is made thicker, the difference between the centrifugal forces C and D generated at the front and rear ends of each chuck segment 9b when the rotating shaft 2 is rotating at high speed becomes even larger. The gripping force of the chuck 9 during rotation can be further strengthened.

FIG. 3 shows another embodiment of the present invention, in which 10 is a ring press-fitted into the rotating shaft 2 (see FIG. 2), 11 is four chuck segments press-fitted into this ring 10, When these chuck segments 11 are combined into a cylindrical shape, the inner diameter of the tip of the chuck segment 11 is
The chuck segment 11 (which becomes the inner circumferential wall surface of the cylinder) is set so that the diameter of the shank 5a is equal to or slightly larger than the diameter of the shank 5a, and the inner diameter of the rear end is smaller than the diameter of the shank 5a.
(see Figure 2) is bent or curved in a dogleg shape.

In this embodiment configured as described above, when the four chuck segments 11 combined in a cylindrical shape are press-fitted into the ring 10 press-fitted into the rotating shaft 2, a chuck having the same function as the chuck 9 shown in FIG. can be formed.

FIG. 4 shows still another embodiment of the present invention.
The same reference numerals as those in the figures and FIG. 3 indicate the same parts, and 2a is a ring-shaped projection protruding from the inner circumferential wall surface of the rotating shaft 2.

In this embodiment configured as described above, when the four chuck segments 11 (see FIG. 3) combined in a cylindrical shape are press-fitted into the protrusion 2a of the rotary shaft 2, the chuck 9 shown in FIG. A chuck with the same function can be formed.

As explained above, according to the present invention, even if the chuck rotates at high speed and centrifugal force is applied to the chuck, there is a difference between the centrifugal force applied to the front end of the chuck segment and the centrifugal force applied to the rear end of the chuck segment. The force is applied to the tip of the chuck segment to grip the shank of the cutting tool, which has the advantage of preventing the chuck gripping force from decreasing during high-speed rotation and further increasing the chuck gripping force. be.

Furthermore, since the area for transmitting the gripping force from the chuck segment to the shank of the cutting tool is large, there is an advantage that the gripping force of the chuck does not drop suddenly even if the inner circumferential wall surface of the chuck segment is worn.

Furthermore, since there are no protrusions on the inner circumferential wall surface of the chuck segment, the shank of the cutting tool can be smoothly inserted into the chuck, and no excessive force is applied to the cutting tool 5, thereby reducing accidents of breaking the cutting tool. There are advantages that can be achieved.

[Brief explanation of the drawing]

Fig. 1a is a sectional view of a dental treatment instrument equipped with a conventional chuck, Fig. 1 is a sectional view of a cutting tool attached to the chuck of Fig. 1a, and Fig. 2a is an embodiment of the present invention. Fig. 2C is a perspective view of the embodiment of the present invention shown in Fig. 2a attached to a rotating shaft, and Fig. 2C is a sectional view of the embodiment of the invention shown in Fig. 2A attached to the rotating shaft. 2d is an operational diagram of one embodiment of the present invention; FIG. 3 is an exploded perspective view of another embodiment of the present invention; and FIG. 4 is a further embodiment of the present invention. FIG. 1... Turbine head, 2... Rotating shaft, 2a. 9a...Protrusion, 3...Bearing, 4,9...
... Chuck, 4a ... Pressing protrusion, 5.
...Blade, 5a...Shank, 6...
...Burst brim, 7...Pur checker, 8
...Turbine blade, 9b, 11...
・Chuck segment, 10...ring.

Claims (1)

[Scope of utility model registration request] When combined in a cylindrical shape, the inner peripheral wall surface of the cylinder is such that the inner diameter of the front end into which the shank of the cutting tool is inserted is equal to or slightly larger than the diameter of the shank, and the inner diameter of the rear end is smaller than the diameter of the shank. A plurality of chuck segments whose surfaces are bent or curved, and an outer circumferential wall surface of the chuck segments combined in a cylindrical shape and an inner circumferential wall surface of the cylindrical rotating shaft are separated from each other, and the chuck segments are separated from the center point of the chuck segments. When the chuck segment is rotatably supported at a position, the chuck segment is separated from a support member attached to the inside of the rotating shaft, and when the chuck segment rotates, a force generated by elastic deformation of the chuck segment is generated. A chuck for a dental treatment instrument, characterized in that the shank is gripped by a difference in centrifugal force generated between the front end and the rear end of the chuck segment.