JPS6153059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for manufacturing a dental reamer or file with good cutting ability, which has a blade shape that has a larger rake angle than conventional ones and a smaller relief angle than conventional ones, and is used for root canal cleaning of teeth. Regarding.

A dental reamer or file (hereinafter referred to as a reamer) is used to remove unfavorable factors from within the root canal of tooth 1 and at the same time smooth the root canal wall, as shown in Figure 1a. and its rotation (3a is the direction of rotation when using a reamer)
It has the function of cutting the root canal wall 2 by pushing and pulling and enlarging the root canal. In other words, the reamer not only has a good sharpness that allows the root canal to be enlarged smoothly in a short time, but also is strong enough to prevent it from bending into the root canal, and has the ability to withstand chemical solutions, dry heat, and disinfection. Austenitic stainless steel is generally used because high corrosion resistance is particularly required. Usually, blades with triangular and square cross sections as shown in FIGS. 1b and 1c are formed into spiral strips as shown in FIG. 1a3. Incidentally, the rake angles of these reamers are all negative, and the former is -
30 degrees, and the latter -45 degrees.

On the other hand, in general cutting, it is known that in order to improve the sharpness of a cutting tool against a workpiece, the rake angle is positive. Therefore, in the case of the above-mentioned dental reamer, if the rake angle is set in the positive direction, the root canal wall of the tooth can be cut with good cutting ability. However, when cutting and enlarging the root canal wall with a reamer, it is necessary to ensure that the reamer does not break during cutting, and to do so, it is necessary to avoid making the cross-sectional area of the reamer too small or making the reamer itself too hard. Excessiveness must be avoided as much as possible.

In order to solve the above-mentioned demands, the present applicant first devised and applied for a dental reamer having a larger rake angle and smaller relief angle than the conventional one (Utility Application No. 114025-1981). Publication No. 57-36912). Figures 2b and 3b are cross-sectional views of the blade of the dental reamer, and the polygon in Figure 2b is
abc and polygon abcd in FIG. 3b correspond to its cross-sectional shape.

The present invention was made in order to manufacture the improved dental reamer as described above, and first, the material of the reamer (straight round wire, square wire, etc.) was A columnar body having a triangular or square cross-section with a shaft diameter larger by the amount crushed and smaller than the shaft diameter of the finished reamer and having a predetermined lengthwise shape by grinding with a grinding device (43386). Next, the columnar body is rotated and moved relative to the processing die for twisting, and the columnar body is continuously rotated from the thickest side, which will become the flank when it is reamed. By applying (or receiving) a twisting force only near the cutting edge of the face and twisting, the corner portion of the cutting edge of the reamer or file is crushed, and the reamer or file has a predetermined taper, a predetermined shaft diameter, and a larger rake angle than before. The present invention also provides a method for manufacturing a dental reamer or file having a smaller relief angle than conventional ones.

Hereinafter, the present invention will be described with reference to examples.

FIG. 2 is a diagram showing an embodiment of the present invention, and shows a method of manufacturing a reamer from a columnar body having a triangular cross section.
Figure a is a side view showing the state in which a columnar body is processed by a processing die, and Figures b and c are AA of Figure A, respectively.
A cross-sectional view and a BB cross-sectional view. In the figure a, 4
is a columnar body formed in a triangular cross section with a predetermined longitudinal shape, which is ground slightly larger than the shaft diameter of the finished reamer by crushing it to make it smaller, and is usually made of austenitic stainless steel. Reference numeral 5 denotes a single frame-shaped processing mold, which is installed at a fixed position. Reference numeral 5a denotes a square processing section, in which the columnar body 4 is subjected to desired processing. Therefore, a material with high hardness and wear resistance is desirable. In figure b, ΔA'B'C' corresponds to this. 5b is a circular hole through which the columnar body 4 can pass. Reference numeral 6 denotes a holder that firmly holds the end portion 4a of the columnar body 4, and allows it to be forcibly rotated in a certain direction 6a and moved by being pulled in a direction 6b (not shown).

Now, with the end 4a of the columnar body 4 firmly held in the holder 6 and the columnar body 4 inserted into the processing die 5 as shown in FIG. tow it and move it. Then, in the circular hole 5b of the processing mold 5, the columnar body 4 rotates without receiving any resistance, but the square processing part 5a
At (△A′B′C′), the cutting edge corners A, B, and C of the columnar body 4 are pressed in the direction opposite to the rotational direction for machining (opposite to the rotational direction when using the reamer) and are crushed. This results in twisting, forming the cross section of polygon abc in figure b. That is, the cutting edge corners A, B, C
The flank surface bends outward (or curves depending on the tool) near the corner of the cutting edge, and the scooping surface curves inward near the corner of the cutting edge. Here, the double length of the line segment connecting the center O of the columnar body and the corner a is the predetermined shaft diameter of the reamer (circumscribed circle diameter)
It is.

By the way, in this case, the scooping angle ∠Oad is naturally larger than the conventional negative scooping angle of 30 degrees. Since all of the rake angles mentioned above have negative values, the rake angle of reamer ABC is larger than that of conventional products.As a result, chips flow out easily, cutting resistance decreases, and the root canal wall 2 Cutting can be improved. In addition, if the amount of crushing is to be extremely large, the rake angle can be set to a positive value, but experiments have shown that a positive rake angle has the disadvantage of digging into the root canal wall too much.

In this example, if the size of the machining angle A′B′C′ for the columnar body ABC is set so that the rake angle ∠Oad is approximately 10 degrees and the relief angle ∠B′af is approximately 40 degrees, then The cutting edge angle ∠daB′ is ∠Oad + ∠OaB′ = 10° + 50° = 60°, which is the same as the cutting edge angle of the conventional product, but since the shape angle is suitable for receiving force, the cutting edge strength is increased accordingly. Become. In addition, together with the increase in hardness due to work hardening of the corner of the cutting edge, cutting of the root canal wall becomes even better. At this time, work hardening occurs only at the corner of the cutting edge, and the center of the reamer is hardly work hardened as in conventional reamers, so only the corner of the cutting edge has strength and strength without losing the flexibility and toughness of the reamer itself. This results in increased durability.

The above-mentioned effects can be exerted on the entire reamer by moving the columnar body 4.

Next, FIG. 3 is a diagram showing another embodiment of the present invention,
1 shows a method of manufacturing an improved reamer from a columnar body having a square cross section. Figure 3a is Figure 2a
FIG. 3b is a side view corresponding to FIG. 2b, and FIG. 3c is a side view corresponding to FIG. 2c. The difference from the case in Fig. 2 is that the columnar body 4' has a square cross section, the square processing part of the processing die 5' has a square section, and □A'B'C' D′ (see figure b)
falls under this category.

In this embodiment as well, as in the case of FIG.
When the holder 6 is rotated in a certain direction 6a and pulled and moved in the direction 6b in the state shown in FIG. When pressed in the opposite direction, it collapses and twists, forming a cross section of polygon abcd in figure b. That is, the flanks of the corner ends A, B, C, and D are bent outward near the corner of the cutting edge, and the scooping surfaces are curved inward at the corner of the cutting edge. Here, ac and bd are the predetermined shaft diameters (circumscribed circle diameters) of the reamer.

Incidentally, in this case, the scooping angle ∠Oae is larger than that of the conventional method, and the cutting of the root canal wall 2 is improved.

In this example, the rake angle ∠Oae is approximately 25 degrees, and the relief angle ∠
If we select machining type A′B′C′D′ for columnar ABCD such that B′af is approximately 25 degrees, then the cutting edge angle ∠
eaB' is ∠Oae + ∠OaB' = 25° + 65° = 90°, which is the same as the conventional product, but the effect can be enjoyed in the same way as in the case of Fig. 2. Further, the above-mentioned effect can be exerted on the entire reamer by moving the columnar body 4, as in the case of FIG. 2.

The above-mentioned embodiment shows a case in which the processing mold is formed as a single body, and a processing mold is used in which a square processing part for processing the columnar body is provided above a circular hole through which the columnar body can pass. This will be referred to as the first embodiment.

Based on this first example, 2/10 of the draft ISO standard
In order to make a No. 100 basic triangular cross-sectional reamer with 0 taper and a 16 mm cutting edge, we experimented with a mold with a triangular twisting part with a circumscribed circle diameter of 1.6mm, and found that the diameter of the starting part of the twist was 1.32mm. It was found that a triangular column with a circumscribed circle diameter of 1.34 mm was suitable, and at the end of the twist, a triangular column with a diameter of 1.06 mm was used to finish the column with a diameter of 1.00 mm.When this was formed by grinding and then twisted, Figure 2 d where the rake angle is approximately -21° at the beginning of twisting.
At the end of the twist, the rake angle was approximately 0°, as shown in Figure 2e.

In this way, in the single processing type, the rake angle and clearance angle change depending on the change in diameter from the twisting start to the twisting end. Furthermore, for example, a thin No. 30 reamer with a taper of 2/100 and a length of 16 mm will not work as well even if it is machined using a triangular torsion part mold with a circumscribed circle that has the same diameter as the finished diameter of the twist start part of 0.62 mm. The inscribed circle of the type is
0.62sin30°=0.31mm, so the 0.30 at the end of twisting rotates freely and cannot be twisted. In other words, in order to insert a columnar body, it is necessary that the diameter of the circumscribed circle of the processing die similar to the cross section of the columnar body be larger than that of the finished reamer, and in order to twist it, the diameter of the inscribed circle must be smaller than the diameter of the finished reamer. No. 30 as a single unit processing type
Since there is no mold that satisfies this condition for the twist start and twist ends, it cannot be processed. By the way, regarding the above-mentioned circumscribed circle and inscribed circle, in the case of a rectangular cross section, the former is the smallest of the circles that pass through at least its three vertices, and the latter is the largest of the circles that are tangent to at least its three sides. shall be taken as a thing.

Therefore, the second method is used when the machining die consists of multiple tools, the size of the machining die is regulated by the copying die, and the size of the machining die and the movement position of the columnar body are maintained in a constant relationship. Let's discuss an example.

FIG. 4 is a diagram showing one embodiment of the above, and shows a method of manufacturing an improved reamer from a columnar body having a triangular cross section, in which a is a side view of the main part, b is a plan view of the main part, and c FIG. 2 is a plan view showing a processing die.

In the same figure a, 4 is a columnar body having a triangular cross section as described above, and its end portion is firmly held by a holder 6.
Reference numeral 7 denotes a movable body, on which a holder 6 is forcibly rotatable (not shown) and a copying die 8 is fixedly installed. The moving body 7 is movable in a direction perpendicular to the base 22 (not shown). One surface of the copying die 8 is in contact with an adjustable stopper 11, and the other surface 8a is in contact with a tip 9a of a piston 9 that fits into a cylinder 10. When the copying die 8, which is rotatably attached to the base 22 of the cylinder 10 by a shaft 10a, moves, the piston tip 9a is displaced by the surface 8a, and this displacement is transmitted to the processing die tool 12a via the levers 14 and 13. Ru. piston 9 and lever 1
4 is rotatably attached by a shaft 14a, and lever 14 and lever 13 are rotatably connected by a shaft 15. Furthermore, the lever 14 is rotatably mounted by a shaft 19'. The surface 8a of the copying die 8 is determined based on the taper of the reamer. Processing mold 12
consists of tools 12a, 12b, and 12c (see figure b). The tool 12a is fixed to the lever 13, the tool 12b to the lever 16, and the tool 12c to the lever 18, the lever 16 is fixed to the base 22 by a bolt 17, and the lever 18 is rotatably attached to the base 22 by a shaft 19. It will be done. Further, the levers 13 and 18 are pulled by springs 20 and 21.

By the way, the tool 12b of the processing die 12 is the lever 1.
6 is fixed to the base 22. Tool 12a
is connected to the piston 9 by the levers 13 and 14, so when the tip 9a of the piston is displaced so as to taper the reamer by the copying die surface 8a, the tool 12a will be deployed at a predetermined position. (see figure c). In this case, tool 12a
performs a horizontal displacement b in the same manner as its vertical displacement a, but these are caused by the swinging of the lever 13 around the shaft 15 and the restraint by the spring 20.
It is possible to move from the position -1 (solid line) to the position 12a-2 (dotted line) without any problem. in this case,
The tool 12c is 12c-1 (solid line) due to the swing of the lever 18 around the shaft 19 and the action of the spring 21.
from the position to the position 12c-2 (dotted line) by a displacement a. In reality, the point B' also moves somewhat due to the swing of the lever 12c, so the lever 16 also moves the lever 1.
It is better to install it in the same way as 8. Thus processing type 1
2 can always maintain the necessary size in accordance with the taper of the reamer. Here, tool 12a,
By moving 12b and 12c, △A′B′C′ (second
This corresponds to △A'B'C' in Figure b. ) becomes △A′ ₁ B′C′ ₁ , which means that the center of the processing die is shifted, but this does not actually cause any problem because the displacement due to the taper is small compared to the length of the columnar body.

Next, the operation of this embodiment will be described. First, the position of the copying die 8 and the size of the processing die 12 are adjusted to a predetermined relationship, and the columnar body 4 is attached to the holder 6. Next, the holder 6 is forcibly rotated in a predetermined direction 6a, and the movable body 7 is moved in the direction 6b. Then, the copying die 8 applies a displacement to the piston tip 9a in accordance with the taper of the reamer and the required amount of crushing of the cutting edge. In response to this, lever 14 and lever 13 actuate tool 12.
The required displacement is transmitted to a. Further, the tool 12c is displaced according to the displacement of the tool 12a, and the machining die 1
2 forms the required size.

Due to the above-mentioned action, the columnar body 4 is always processed using the processing die 12 of an appropriate size. As a result, it is possible to obtain a reamer having a larger rake angle and a smaller clearance angle than the conventional reamer as described in the case of FIG. Furthermore, in the case of this embodiment, compared to using the single-piece machining die described above, machining can be performed that is more in line with changes in the shaft diameter due to the taper of the finishing reamer, and the effects of the present invention are more pronounced. can be enjoyed.

Figure 5 is a diagram showing another embodiment, showing a method of manufacturing a reamer from a columnar body with a square cross section, in which a is a side view of the main part, b is a plan view of the main part, and c is a working mold. FIG.

As is clear from the drawing, in the case of a rectangular cross section, there are four tools for the machining die 12' (see figure c), and in tool adjustment, tool 12'b is fixed, tool 12'c is moved laterally, tool 12' is moved horizontally, and tool 12' is moved horizontally. In addition to the vertical and horizontal movement 'a', the tool 12'd also needs to be moved vertically. For this reason, in addition to the adjustment system of the tool 12'a using the copying die 8, piston 9, levers 14, 13, etc., the adjustment of the tool 12'd using the copying die 8', piston 9', levers 14', 13', etc. A system was established (see figure b). The effect is almost the same as in the case described above.

In the case of this embodiment as well, the same effects as in the case of FIG. 4 can be enjoyed.

In the description of the above embodiment and in FIGS. 4 and 5, the tool is expanded and contracted by swinging to form a triangular or quadrangular machining area. For example, in FIG. 4c, the tool 12a is moved in the direction A'B' Additionally, the tool 12c can be configured to move in parallel in the C'B' direction.

The first embodiment uses the unitary processing die shown in FIGS. 2 and 3, and the copying die 8 shown in FIGS. In contrast to the second embodiment in which the columnar body is expanded and contracted, the third embodiment shown below is an example in which the size of the processing mold is expanded and contracted in accordance with the size of the cross section of the twisted portion of the columnar body, and is twisted.
Specifically, as shown in Fig. 6a, a protruding measuring part 12a-A and a processing part 12a-B are provided at the tip of the tool, and the size (distance from the center to the side) of the columnar body of the part to be twisted is determined. An example in which the measurement part 12a-A measures 1, and the processed part 12a-B, which is a certain dimension larger than the measurement part 12a-A, applies twisting force only near the cutting edge of the flank surface, thereby twisting while crushing the corner part of the cutting edge. It is. That is, a measuring section A and a processing section B are provided at the tips of the respective tools 12a, 12b, etc. of the divided processing mold, and the columnar body is gripped by the measuring section A as shown in Fig. 6b, and the processing at that time is performed. This is an example of manufacturing a reamer with improved rake angle and clearance angle as described above by twisting the reamer in the state shown in FIG. 6c formed by the parts. The feature of this third embodiment is that it is possible to easily form a processed portion that follows the size of the columnar body without using a separate copying die. In other words, the third embodiment uses a mold that is a certain size larger than the size of the columnar body, and is not a certain proportion larger, so it is not as extreme as the single-piece processing mold of the first embodiment, but the original thick part is There is little improvement in rake angle and relief angle, and the improvement is large in the narrow part. In the above explanation and FIG. 6, the processing mold for the size of the columnar body was formed by the step between the measuring part A and the processing part B of the processing mold, but the measuring part was electrically
Alternatively, a sensor such as a photoelectric sensor may be used, but it is also possible to embed a sensor in the processing section itself and determine the size of the processing section based on the sensing by this sensor section. In this case, there is no longer a limitation that the processed portion be a certain size larger than the size of the columnar body.

The present invention has the above-mentioned configuration, operation and effect, and first grinds a columnar body having a cross section larger than the finished reamer shaft diameter by the amount of crushing and a predetermined shape in the length direction. It is formed by processing, etc., and then the inner side of the processing mold that forms the square shape is set at a certain position, and by pulling and moving the columnar body while rotating, it becomes the flank surface of the columnar body. A torsional force is applied only near the cutting edge of the face to crush the corner of the cutting edge, producing a dental reamer or file with a predetermined taper and a predetermined shaft diameter, a larger rake angle than conventional ones, and a smaller relief angle than conventional ones. can do. In addition, when using a single processing die, the purpose can be achieved with a relatively simple device, and when using a processing die consisting of multiple tools, the shaft diameter can be achieved by adjusting the finish reamer or file taper. It is possible to perform processing that is more in line with the changes in the reamer or file, and can expect the effect of being able to manufacture reamers or files with higher precision.

Furthermore, it is manufactured using a single-piece processing die of the first embodiment and a processing die that is a certain dimension larger than the size of the columnar body of the twisting portion shown in FIG. 6 of the third embodiment. A reamer with a small base and a large tip with improved scooping angle and clearance angle has a reamer blade length of 16 mm, but only a few mm of the tip is mainly used, so it is possible to scoop the entire area uniformly. It can be used in the same way as a reamer or file with an improved clearance angle, and in applications where you do not want to shave off the original surface too much (such as when forming a so-called apical sheet, which is a reamer with a cutting edge only at the tip), the entire surface is uniform. It has characteristics that make it more effective than the improved version. Further, the processing die that is expanded and contracted by the copying die 8 of the second embodiment is the copying die 8.
By adjusting , the same product as the first and third embodiments can be manufactured, or conversely, the rake angle relief angle of the original thick part can be greatly improved, and the improvement of the tip part can be made less. It is also possible to manufacture a special reamer or file that mainly cuts the flared part without cutting too much of the root canal near the root apex.

The above explanation mainly focused on improving the rake angle clearance angle in rotary cutting, that is, reaming.
The rake angle relief angle in push-pull cutting, or filing, is the angle in the longitudinal section. FIG. 7 is a longitudinal section of a reamer and file made from a columnar body with a triangular cross section.

FIG. 7a shows a conventional reamer, and FIG. 7b shows an improved rake angle relief angle manufactured by the method of the present invention.
An example of a file, the rake angle is -10° and the conventional product is -
It is improved by 20° compared to 30°. That is, the present invention is also effective in filing.

Furthermore, as shown in Figure 8a, by twisting a columnar body with an equilateral triangular cross section using a right triangular processing die with one angle of 60°, the two cutting blades can be used to scoop the same way as when twisted using an equilateral triangular processing die. It is also possible to set one cutting edge to a square clearance angle and set the other cutting edge to a scooping angle and clearance angle different from the other two. Further, as shown in FIG. 8b, by twisting a columnar body having a rhombic cross-section using a parallelogram-shaped processing die instead of a rhombus, it is possible to improve the rake angle clearance angle of only the two cutting edges. In other words, by twisting using a processing die that is not similar to the cross-sectional shape of the columnar body, it is possible to manufacture a reamer or file having the respective characteristics. The shape is not limited to, and may be an isosceles triangle, a rhombus, a rectangle, or a polygon partially curved. This is possible regardless of whether it is a single piece or a telescoping type.

[Brief explanation of the drawing]

Figure 1 shows a conventional dental reamer, where a is a front view, b and c are cross-sectional views, b is a triangular cross-section, and c is a cross-sectional view.
indicates the case of a rectangular cross section. 2 and 3 are diagrams showing the case where a single-piece processing mold, which is an embodiment of the present invention, is used, respectively. FIG. 2 is a diagram showing a method for manufacturing, in both figures, a is a side view;
b is an AA sectional view of a, and c is a BB sectional view of a. FIG. 4 and FIG. 5 are diagrams each showing another embodiment of the present invention in which a processing die that expands and contracts in accordance with the position in the length direction of a columnar body made up of a plurality of tools is used. 5 is a diagram showing a method of manufacturing a dental reamer from a columnar body having a triangular cross section, and FIG.
), b is a plan view of the main part, and c is an enlarged plan view of the processing type. FIG. 6 is another embodiment of the present invention in which a processing die corresponding to the size of the twisted portion of the columnar body is used, in which figure a is a front view thereof, figure b is a measuring part, and figure a It is an AA sectional view of the figure. Moreover, figure c shows the processed part, and is a BB sectional view of figure a. FIG. 7 shows a reamer manufactured by the method according to the present invention,
In the vertical cross-sectional view of the file, a is according to the conventional example;
b was produced by the method of the present invention. 8th
The figures show an example in which the processing mold is not similar to the cross-sectional shape of the columnar body, where a is a diagram of an equilateral triangular columnar body using a right triangular processing die with one angle of 60°, and b is a diagram of a rhombic columnar body made into a rhombus shape. This figure shows the improvement of the rake angle relief angle of the two cutting edges using a parallelogram processing die. 4, 4'... Column body, 5, 5'... Processing mold, 6...
... Holder, 7... Moving body, 8, 8'... Copy mold,
9,9'... Piston, 11... Stopper, 1
2, 12'... processing mold, 13, 13', 14, 1
4'16, 18... Lever, 20, 21, 21'...
...Spring, 22...Base.

Claims (1)

[Claims] 1. A method for manufacturing a dental reamer or file, in which a columnar body having a triangular or quadrangular cross-sectional shape and a predetermined longitudinal shape is twisted while crushing the cutting edge portion with a processing die. , the processing die is expandable and retractable, and the processing die is expanded and contracted in accordance with the position in the length direction of the columnar body or in accordance with the cross-sectional size of the columnar body at the portion to be twisted; By rotating and moving the columnar body and the processing mold relative to each other, a twisting force is continuously applied to the flank surface of the columnar body near the cutting edge, and the corner portion of the cutting edge is crushed and twisted. A method for manufacturing a dental reamer or file having a larger rake angle and smaller clearance angle than conventional ones. 2. The method for manufacturing a dental reamer or file according to claim 1, wherein the processing mold has a cross-sectional shape that is either similar or dissimilar to the cross-sectional shape of the columnar body.