JPH0257426B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of manufacturing a dental bur.

(Prior art) Generally, when manufacturing dental diamond burs, a base metal is inserted into a large number of diamond abrasive grains, and electroplating is performed to deposit a metal layer on the surface of the base metal. The abrasive grains are fixed by the precipitated metal layer.

(Problems to be Solved by the Invention) However, in the above method, as shown in FIG. 10, the density of the abrasive grains 10 fixed to the surface of the base metal 11 is low, and It was difficult to manufacture bars. This means that if the base metal 11 is simply inserted into a large number of abrasive grains, only 10 abrasive grains
Although some of the abrasive grains are almost in contact with the base metal 11, as shown in FIG.
This is because the bridged abrasive grains are not fixed, and the density decreases accordingly. Also,
Dental burs manufactured by the above method have a problem of short lifespan due to their low density. This point is
This problem arises because it is a dental diamond bur, and was discovered as a result of intensive research by the applicant.

That is, since the diamond grindstone used for machining has a large diameter, the length of contact with the workpiece during one rotation of the grindstone is long. Therefore,
The amount of grinding of the abrasive grains per rotation of the grindstone increases. For this reason, if the density of the abrasive grains is increased, chips may become stuck between the abrasive grains, thereby shortening the service life.

On the other hand, dental diamond burs are extremely thin, usually having a diameter of 1 mm or less. Therefore, unlike diamond grindstones used in machining, there is relatively little reduction in service life due to chip clogging. On the other hand, if the density of the abrasive grains is made coarser, as in the case of diamond grinding wheels for machining, the number of abrasive grains located on the same circumference will be extremely reduced because the diameter of dental diamond burs is small, and the number of abrasive grains located on the same circumference will be extremely reduced. The grains will be forced to undergo heavy grinding. This heavy grinding shortens the service life.

Therefore, the present applicant has developed a method for manufacturing a dental bur that can increase the density of abrasive grains.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and its gist is to provide abrasive particles on the surface of the base metal with the base metal inserted into a large number of abrasive grains. In the method for manufacturing a dental bur in which a metal layer thinner than the diameter of the metal layer is deposited by a plating method to fix abrasive grains to the base metal, the following (a):
There is a method for manufacturing a dental bur, characterized in that (b) and (c) are essential components.

(a) Repeating the precipitation of the metal layer and the accompanying fixation of the abrasive grains two or more times.

(b) After depositing the metal layer and fixing the abrasive grains,
Before the next metal layer and abrasive grains are fixed, the arrangement of the base metal with respect to a large number of abrasive grains is changed so that the abrasive grains to be newly fixed are located between the previously fixed abrasive grains.

(c) The total thickness of all metal layers is made so that all abrasive grains protrude from the surface of the metal layer deposited in the final step.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 9 shows an apparatus for carrying out the method of the invention. 1 in the figure is a plating tank, and this plating tank 1 contains an electrolytic solution 2 containing a metal such as nickel.
is accommodated. An ion-permeable ceramic container 3 and an electrode plate 4 are immersed in the electrolytic solution 2.

An example of a method for manufacturing a dental diamond bur using the above apparatus will be described with reference to FIGS. 1 to 8. First, a large number of diamond abrasive grains 10 are placed in a container 3, and then the container 3 is immersed in an electrolytic solution. Next, the base metal 11 is inserted into the abrasive grains 10. The base metal 11 has a shank part 11a and an action part 11b.
A masking agent (indicated by diagonal lines) is applied to the surface of the shank portion 11a, and a base plating is applied to the active portion 11b as required.

In the above inserted state, as shown in Figure 1,
Among the large number of abrasive grains 10, the abrasive grains 10 that are in contact with the surface of the working portion 11b of the base metal 11 or very close to this surface have a low density.

In this state, by passing a current between the base metal 11 and the electrode plate 4, the base metal 1
A metal layer 15 (hereinafter referred to as the first
This precipitated metal layer 1 is then deposited.
5, the abrasive grains 10 near the surface of the working part 11b
(hereinafter referred to as primary abrasive grains) are fixed. In this case, the thickness of the primary metal layer 15 is made significantly smaller than the diameter of the abrasive grains 10, as will be described later. Therefore, a portion of each primary abrasive grain 10 protrudes from the primary metal layer 15. Note that, since the shank portion 11a of the base metal 11 is subjected to a masking treatment, precipitation of a metal layer and adhesion of abrasive grains do not occur.

Next, this base metal 11 is temporarily pulled out from the container 3, and excess abrasive grains are brushed off from the base metal 11 by rubbing it with a brush or applying ultrasonic vibration to the base metal 11 or the electrolyte 2 (second figure). At this time,
Of course, the abrasive grains 10 that are bridge-shaped on top of the fixed abrasive grains 10 are brushed off.
As shown in FIG. 6, among the primary abrasive grains 10 fixed to the primary metal layer 15, some are buried shallowly in the primary metal layer 15, and only the sharp parts are buried. (hereinafter referred to as temporarily fixed abrasive grains)
Because the holding force by the primary metal layer 15 is weak,
By the above-mentioned scraping operation, it is removed from the primary metal layer 15 (FIG. 7). Therefore, base metal 11
while being in contact with the primary metal layer 1 in a stable posture.
Only the primary abrasive grains 10 that are deeply embedded in the grains 5 and firmly fixed remain. As is clear from this point, in the present invention, abrasive grains that are not fixed to the base metal are not only abrasive grains that are not in contact with the metal layer at all, but also abrasive grains that are weakly held by the metal layer,
Therefore, it also includes abrasive grains that are removed from the base metal by the above-mentioned removal operation.

Next, the action part 11b of the base metal 11 is attached to the container 3 again.
The abrasive grains 10 are embedded in the abrasive grains 10 contained in the abrasive grains. At this time,
Since the abrasive grains bridged over the fixed abrasive grains 10 and the temporarily fixed abrasive grains have been brushed off, when the base metal 11 is buried in a large number of abrasive grains 10 again, the fixed abrasive grains are newly fixed. The abrasive grains 10A (hereinafter referred to as secondary abrasive grains) are now located between the primary abrasive grains 10, and the base metal 1 for many abrasive grains 10 is
The arrangement status of 1 changes. As is clear from this content, in the present invention, "changing the arrangement state of the base metal 11 with respect to a large number of abrasive grains 10" means that the abrasive grains that are not fixed to the base metal 11 and temporarily fixed abrasive grains are The abrasive grains that are not firmly fixed to the gold 11 are removed from the base metal 11, and the abrasive grains 10A to be newly fixed are positioned in the removed portions, that is, the portions between the firmly bonded abrasive grains 10. It means to do something. After that, a new metal layer 15A (hereinafter referred to as a second metal layer) is formed in the same manner as above.
is precipitated to fix the secondary abrasive grains 10A in contact with or in the vicinity of the primary metal layer 15. In this case, the thickness of the second metal layer 15A is smaller than the diameter of the second abrasive grain 10A, and the total thickness of the second metal layer 15A and the first metal layer 15 is smaller than the first metal layer 15A.
It is made smaller than the diameter of the secondary abrasive grains 10. Therefore, not only the secondary abrasive grains 10A protrude from the secondary metal layer 15A, but also the primary abrasive grains 10.

Next, a dental diamond bur is obtained by pulling out the base metal 11 from the container 3 and shaking off excess abrasive grains.

As is clear from the comparison between FIG. 4 and FIG. , 10A are arranged with high density. In other words, if the abrasive grains are fixed with only one metal layer, as is clear from FIG. In some cases, other abrasive grains are strung across in a bridge shape, and the abrasive grains are not fixed to the surface of the base metal corresponding to the abrasive grains strung over in a bridge shape. Therefore, as shown in FIG. 2, it is only possible to manufacture abrasives in which the density of the abrasive grains is reduced.

In this regard, in the manufacturing method of the present invention, the base metal 11 is pulled out of the abrasive grains 10 and inserted into the abrasive grains 10 again every time the fixation is performed, so for example, at the time of the first fixation, At the locations where the abrasive grains 10 are not fixed, the abrasive grains 10A are fixed during the second and subsequent fixings. Therefore, the abrasive grain density can be significantly improved compared to conventional ones.

Note that, as in this embodiment, when the primary abrasive grains 10 and the secondary abrasive grains 10A are of approximately the same diameter, the secondary abrasive grains 10A are the same as the primary abrasive grains 10A.
0 by the thickness of the first metal layer 15, but as will be described later, since the thickness of the first metal layer 10 is small, there is almost no problem in grinding. Of course, if the secondary abrasive grains 10A are smaller than the primary abrasive grains 10 by the amount of the first metal layer 15, the base metal 11 of the abrasive grains 10, 10A
The height of the protrusion can be made the same. This point will also be discussed later.

Next, to explain the advantages of the dental diamond bur manufactured as described above, we will first discuss the correlation between the abrasive grain retention rate (the ratio of the metal layer thickness to the abrasive grain diameter) and the grinding function. Let me explain. If you grind for a long time, the cutting edge of the abrasive grain (the sharp part formed on the surface of the abrasive grain) will wear out and become rounded.
Friction with the ground surface increases. For this reason, the abrasive grains are subjected to a large force and fall off from the base metal, leaving only the abrasive grains with less wear on the cutting edge. When the retention rate is low, the retention force provided by the metal layer is weak, so worn abrasive grains tend to fall off the base metal, resulting in good sharpness but short life. Further, when the retention rate is high, worn abrasive grains are difficult to fall off from the base metal, so the life is extended, but the sharpness becomes poor. Generally retention rate is 45
% to 70% is considered appropriate.

In the above embodiment, since the primary abrasive grains 10 and the secondary abrasive grains 10A have the same diameter, the secondary abrasive grains 10A are
The first metal layer 15 protrudes beyond the first abrasive grain 10, and is particularly effective when performing heavy grinding. Heavy grinding means applying a large force to the diamond bur to grind the teeth, which also generates a large amount of chips. At the initial stage of heavy grinding, grinding is mainly performed using the secondary abrasive grains 10A. At this time, between the secondary abrasive grains 10A, that is, between the primary abrasive grains 10A
Since the upper part is recessed to form a chip pocket 20, a large amount of generated chips is accommodated in the chip pocket 20 and does not interfere with grinding by the secondary abrasive grains 10A. Further, if grinding is continued for a long time, a large force is applied to the worn secondary abrasive grains 10A of the cutting edge. The secondary abrasive grains 10A are held only by the secondary metal layer 15A, and because of their low retention rate, they easily fall off. Therefore, only the unworn secondary abrasive grains 10A remain, and good sharpness can be maintained. After the secondary abrasive grains 10A fall off,
Grinding is performed using primary abrasive grains 10. At this time, as shown in FIG. 5, since a deep recess, that is, a chip pocket 21 is formed at the site where the secondary abrasive grains 10A have fallen, chips can be stored in the chip pocket 21. As mentioned above, the chip pocket 20,2
By being able to accommodate chips in the grinder 1 and having good sharpness, heavy grinding can be carried out effectively. In addition, 10A of secondary abrasive grains arranged at high density
Since grinding can be performed in two stages using the primary abrasive grains 10 and the primary abrasive grains 10, the service life is extended.

In the above embodiment, the thickness of the first metal layer 15
Let T ₁ be 5 to 30% of the diameter D ₁ of the primary abrasive grains 10.
If it is 5% or less, the first metal layer 15
This is because it is not possible to reliably temporarily hold the secondary abrasive grains 10. If it is 30% or more, the number of primary abrasive grains 10 fixed to the primary metal layer 15A increases, and the This is because the effect of the present invention cannot be expected because the number of secondary abrasive grains 10A is reduced. Further, the total thickness of the thickness T ₁ of the first metal layer 15 and the thickness T ₂ of the second metal layer 15A is equal to the total thickness of the first abrasive grain 15
The diameter _D1 shall be 45 to 70%. As mentioned above, if the retention rate of the primary abrasive grains 10 is less than 45%, the life will be short, and if it is more than 70%, the sharpness will deteriorate.

More preferably, the thickness of the first metal layer 15
T ₁ is approximately 20% of the diameter D ₁ of the primary abrasive grains 10, and the thickness T ₂ of the secondary metal layer 15 is the diameter of the primary abrasive grains 10.
Approximately 40% of _D1 . As a result, primary abrasive grains 10
The retention rate of the secondary abrasive grains 10A is approximately 60%, and the retention rate of the secondary abrasive grains 10A is approximately 40%. The retention rate of the secondary abrasive grains 10A is slightly lower than the generally appropriate retention rate range of 45 to 70%, so it easily falls off but is very sharp. In addition, the height of the chip pocket 20 at the initial stage of grinding is equal to the diameter D ₁ of the primary abrasive grains 10.
Since it is about 20% of the total amount, it can accommodate enough chips.

Note that the diameters of the abrasive grains 10 and 10A have a normal distribution or a distribution similar to this within a predetermined range, and the above numerical limitations are discussed based on the average value of the diameters. The average value is located at or near the top of the distribution.

The present invention is not limited to the above embodiments, and various embodiments are possible. For example, in the example shown in FIG.
The secondary abrasive grain 10A has a diameter D _{2 approximately equal to the value obtained by subtracting the thickness T 1 of} the first metal layer 10 from the diameter D 1 _of the primary abrasive grain 10 . As a result, the primary abrasive grain 1
0 and the secondary abrasive grains 10A are arranged at high density with almost the same protrusion height, and almost all the abrasive grains 1
Since 0 and 10A perform grinding at the same time, it is ideal for light grinding and requires a clean finish, and has a long life. Specifically, the thickness T ₁ of the primary metal layer 15 is approximately 20% of the diameter D ₁ of the primary abrasive grains 10.
The thickness T ₂ of the secondary metal layer 15A is approximately 40% of the diameter D ₁ of the primary abrasive grain 10,
The diameter D ₂ of the primary abrasive grains 10 is set to approximately 80% of the diameter D ₁ of the primary abrasive grains 10.
In this way, the retention rate of primary abrasive grains 10 is 60
%, the retention rate of the secondary abrasive grains 10A is 50%, which is in the range of 45 to 70%, which is generally said to be suitable.

Furthermore, in the present invention, after the first metal layer is deposited and the abrasive grains are fixed accordingly, the current is stopped and the plating method is performed without pulling out the base metal from the abrasive grains. By stopping the process and applying ultrasonic vibration to the base metal or electrolyte in this state, the arrangement of the abrasive grains on the surface of the base metal is changed, and then the plating method is performed to form the second metal layer. The precipitation of the abrasive grains and the accompanying fixation of the abrasive grains may also be performed.

Furthermore, in the present invention, metal deposition and abrasive grain fixation by a plating method may be performed three or more times, or metal deposition and abrasive grain fixation may be performed by a chemical plating method. .

(Effects of the Invention) As explained above, according to the method of the present invention, a dental bur with a high density of abrasive grains can be manufactured. In addition, the produced dental bur has a high abrasive grain density and therefore has a long life. Furthermore, by selecting the diameter of the abrasive grains and the thickness of the metal layer, it is possible to manufacture the optimal dental bur depending on the application, such as heavy grinding or light grinding.

[Brief explanation of the drawing]

Figures 1 to 7 show an embodiment of the method of the present invention, Figures 1 to 4 are enlarged cross-sectional views showing the state of adhesion of abrasive grains on the surface of the base metal in the order of the manufacturing process, and Figure 5 is a An enlarged sectional view showing the fixed state of the abrasive grains after time grinding, FIGS. 6 and 7 are enlarged sectional views showing the fixed state of the abrasive grains before and after brushing off, and FIG. 8 shows the invention An enlarged cross-sectional view showing a fixed state of abrasive grains obtained as a result of carrying out another example of the method,
FIG. 9 is a cross-sectional view showing an embodiment of an apparatus for carrying out the method of the present invention, and FIG. 10 is an enlarged cross-sectional view showing the fixed state of abrasive grains obtained by the conventional method. 10... Primary abrasive grains, 10A... Secondary abrasive grains,
11...Base metal, 15...First metal layer, 15A...
...Second metal layer.

Claims (1)

[Scope of Claims] 1. With the base metal inserted into a large number of abrasive grains, a metal layer thinner than the diameter of the abrasive grains is deposited on the surface of the base metal by a plating method to fix the abrasive grains to the base metal. A method for manufacturing a dental bur, characterized in that the following (a), (b), and (c) are essential components. (a) Repeating the precipitation of the metal layer and the accompanying fixation of the abrasive grains two or more times. (b) After depositing the metal layer and fixing the abrasive grains,
Before the next metal layer and abrasive grains are fixed, the arrangement of the base metal with respect to a large number of abrasive grains is changed so that the abrasive grains to be newly fixed are located between the previously fixed abrasive grains. (c) The total thickness of all metal layers is made so that all abrasive grains protrude from the surface of the metal layer deposited in the final step. 2. The precipitation of the metal layer and the fixation of the abrasive grains accompanying this are performed twice in total, the thickness of the first metal layer is set to 5 to 30% of the diameter of the first abrasive grains, and the thickness of the first metal layer and the second abrasive grain are The method for manufacturing a dental bur according to claim 1, wherein the total thickness of the secondary metal layer is 45 to 70% of the primary abrasive grains. 3. The method for manufacturing a dental bur according to claim 2, wherein the primary abrasive grains and the secondary abrasive grains have approximately the same diameter. 4 The primary abrasive grains and the secondary abrasive grains are almost the same type,
The thickness of the primary metal layer is approximately 20% of the diameter of the primary abrasive grain, and the thickness of the secondary metal layer is approximately 40% of the diameter of the primary abrasive grain.
%. The method for manufacturing a dental bur according to claim 3. 5 Change the diameter of the secondary abrasive grains from the diameter of the primary abrasive grains.
3. The method of manufacturing a dental bur according to claim 2, wherein the thickness of the dental bur is approximately equal to the value obtained by subtracting the thickness of the second metal layer. 6 The thickness of the primary metal layer is approximately 20 times the diameter of the primary abrasive grain.
%, the thickness of the secondary metal layer is approximately 40% of the diameter of the primary abrasive grains, and the diameter of the secondary abrasive grains is approximately 80% of the diameter of the primary abrasive grains. The method for manufacturing a dental bur according to item 5.