JPH03164048A - Metal graphite brush for small-sized motor and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve wear resistance and conductivity by kneading refined graphite having an ash content of 0.05wt.% of lower with binder containing 0.1-15wt.% wear resistant and conductive substance of 50mum or smaller particle size, pressure molding it, and baking it. CONSTITUTION:Graphite material is refined to reduce the ash content to 0.05wt.% or lower by using substance for isolating halogen in a high temperature atmosphere of inert gas. When the refined graphite is kneaded with binder, wear resistant and conductive substance having a 50mum or smaller particle size is added in a range of 0.1-15wt.% of binder. The additive includes, for example, one or more of carbide such as TiC, ZrC, Tac, etc., nitride such as TiN, ZrN, TaN, etc., boride such as TiB2, CrB2, MoB, etc., silicate such as TiSi2, ZrSi2, TaSi2, etc., which are kneaded, pressure molded, and sintered. Thus, a product having excellent wear resistance and conductivity is manufactured.

Description

[Detailed Description of the Invention] [Summary] Regarding a carbon brush used in a small motor having a permanent magnet field, the purpose of this invention is to provide a carbon brush with particularly improved rectification characteristics and wear resistance. The graphite powder used for this purpose is one that has been refined to an ash content of 0.05 wt% or less, and the graphite powder is coated with abrasion-resistant and conductive 'pA powder with a particle size of 50 microns or less.
．． It is added to the binder in an amount of about 1 to 15.0 wt%.

[Industrial application field]

The present invention relates to carbon brushes used in small motors, particularly metal graphite brushes for small motors having a permanent magnet field, and a method for manufacturing the same.

[Conventional technology] Conventional. As a carbon brush in a small motor.
A binder is added to graphite raw material refined to about 98% to 99.5%, and the solidified material is crushed and sieved to obtain the desired conductivity as necessary. The material used is manufactured by performing a metal powder addition and mixing process to give the metal powder, followed by a pressure molding process, and then a firing process.

Furthermore, the point of using the binder mentioned above has been eliminated. A so-called coated graphite brush is known. The copper-plated graphite brush is. Copper plating is performed on powder particles of graphite raw material that has been refined to about 99%. It is manufactured by press-molding the plated graphite powder as it is, that is, without adding a binder, and then subjecting it to an incineration treatment.

[Problem to be solved by the invention] In the former case described in the above conventional technology. Pressure molding of male lead powder (contains ash) with binder. It is to be fired. Metal satolead brushes are manufactured using conventional technology in which the graphite raw material, which has been solidified by adding a binder, is crushed and sieved, mixed with metal powder, pressure-molded, and then fired. Normally, lead raw materials contain impurities with particle sizes of about 1 micron to 500 microns.

FIG. 6 shows an electron micrograph of impurities contained in the graphite raw material, and it can be seen that impurities with considerably large particle sizes are included.

The main component of such impurities is Sin2Al. ○
s+FezOs+Mno, MgO, TiO, silicates, and other oxides. These oxides as impurities have a particle size of 50 microns or more. Add metal powder. If some treatment is not performed before mixing, particles will enter between the commutator and the brush during pressure molding and burning and use as a carbon brush, deteriorating the commutating properties. In some cases, the commutator and brushes are insulated and the motor is stopped.

Therefore, in one of the separate patent applications already filed by the same applicant as the present application, the graphite raw material was first subjected to high purity treatment to reduce the proportion of impurities contained in graphite to 0.05 wt%.
Along with the following. In the next binder treatment process, oxides with a particle size of 50 microns or less (s iOX
,Aez○3+Ffl'l○,,MnO,MgO,Ti
○． silicate). It is added in a range of 0.1 to 10.0 wt%, treated with a binder, and then crushed and sieved. We proposed a metal graphite brush that mixes metal powder, pressurizes it, and burns it, and its manufacturing method.

When a metal graphite brush manufactured by the manufacturing method proposed in the above application was used in a small motor, its performance improved in terms of both rectification characteristics and wear resistance. however. Oxides are generally insulating substances, so they have no conductivity. Graphite to which the oxide has been added also makes it difficult for current to flow, which remains a problem.

The present invention solves the problems existing in the above-mentioned prior art. The object of the present invention is to provide a metal graphite brush for a small motor that has good rectification characteristics, high wear resistance, and high conductivity, and a method for manufacturing the same.

[Means for Solving the Problems] In order to achieve the above object, the first invention provides a permanent magnet as a field and a small-sized magnet that is rotated by commutation through a commutator. Used for motors. In a metal graphite brush for a small motor that is formed by bonding graphite powder and is configured to slide on the commutator, the graphite raw material is treated to a high purity so that the ash content contained as an impurity in the graphite powder is 0.05. For those purified to less than wt%. 0.1 wt% to 15.0 wt.
%, then pressure molded and fired. A technical method was adopted.

In the present invention. TiC is a wear-resistant and conductive material.
, ZrC, HfC, VC, NbC, TaC, Cr+Cz
, M o C, WC, etc. or 2 or more types? Carbide whose main component is TiN, ZrNN b N, T
aN. CrzN, VN, etc. 1 or 2
Nitride whose main component is T i B Z, Z
r B 2+NbB. , TaBz , CrB, MoB,
A boride mainly containing one or more of WBLaB, VBz, etc., or T i Siz, Z r S
i■NbSi. , TaSi. ,CrSiz,MoSiz
, WSiz, and the like can be used.

Next, in the second invention, a permanent magnet is used as a field magnet and is used in a small motor that is rotated by commutation through a commutator, and is formed by bonding graphite powder and has the above-mentioned commutator. A method for manufacturing a metal graphite brush for a small motor with sliding grooves includes a high-purity treatment process for refining graphite raw material using a substance that liberates halogen in a high-temperature atmosphere of inert gas. After the graphite powder that has undergone the high-purity treatment process is solidified with a binder, the graphite material solidified with the binder is crushed and sieved. A mixing process of adding and mixing metal powder, a pressure forming process of pressurizing the d-combined powder, and a burning process of burning the press-formed product. In the binder treatment step or the mixing treatment step, 0.1 wt% to 15.0 wt% of a wear-resistant and conductive material powder with a particle size of 50 microns or less is added.
A metal graphite brush is manufactured by adding the metal in a range of wt%. A technical method was adopted.

Figure l shows the principle diagram of the metal graphite brush of the present invention.
Diagram (A) is the principle composition diagram. FIG. 1(B) shows an explanatory diagram of the manufacturing process.

In Figure I (A). The symbol l is a commutator. 2 is a commutator piece. 3 represents a rotating shaft, 4 represents a carbon brush, and 5 represents a brush elastic body.

The carbon brush 4 is supported by an electrically conductive brush elastic body 5 and is supported so as to slide on the commutator bar 2.2.2. The carbon brush 4 is fired into a convex shape, for example, as shown in Figure A-1, which is a perspective view. The convex head is supported by the brush elastic body 5. A slightly curved surface is formed on the surface corresponding to the base of the convex shape. The curved surface slides on the commutator piece 2.

Also in Figure 1 (B). 20 is a graphite raw material which is the source of carbon plastic 4 according to the present invention, for example, 99
21 is the high purity treatment step 9 according to the present invention, and 22' is the binder treatment step. In other words, it is a wear-resistant material. and carbide as a conductive material. Nitride. Boride or silicide with a particle size of 50 microns or less in an amount of 0.1 wt% to 15. Owt%. A processing process that hardens graphite rice powder by adding it to a binder. 23 is the crushing and sieving process. 24 is a mixing process of mixing treated graphite powder and metal powder. 25 represents a pressure molding process, and 26 represents a firing process.

The carbon brush 4 shown in FIG. 1(A) is. Figure 1 (
B') As shown. The graphite raw material 20 is subjected to a high purity treatment process 21, a binder treatment process 22', a crushing/sieving process 23, a metal powder mixing process 24, a pressing process 25, and a firing process 26. Manufactured by executing.

[Function] In the above manufacturing process, the high purity treatment process 21 is performed so that the graphite powder has impurities (ash content) of 0.05 wt% or less in the state before the binder treatment process 22' is performed. The manufactured carbon brush 4
The particles corresponding to the impurities in the graphite particles are 0.05 wt.
% or less.

therefore. Since the impurities are extremely low, the carbon brush produced through the subsequent processing steps has excellent rectification properties.

Furthermore, in the binder treatment step 22', 0.1 to 15-t% of a wear-resistant and conductive substance with a particle size of 50 microns or less is forcibly added to the graphite raw material treated to high purity. Experimental results have revealed that the wear resistance of the carbon brush of the present invention can be increased by doing so.

? Embodiment] FIG. 2 shows a conceptual diagram of a refining furnace used in the high purity treatment process according to the present invention. Reference numeral 20 in the figure indicates graphite raw material It. 30
represents the furnace body, 31 represents the transformer, and 32 represents the halogen gas pipe. High purity treatment process. Substances that easily release halogen at high temperatures in an inert gas such as nitrogen or argon, such as CC
I. It corresponds to the process of removing impurities in the graphite raw material using , C(1.F., etc.).

That is, the graphite raw material 20 is put into the furnace body 30. A halogen gas pipe 32 is placed below the raw material 20.

When the temperature of the furnace was raised to about 1800°C, ccp.
is saturated with an inert gas and fed through a halogen gas pipe 32. In this case. It can be assumed that the following reaction takes place. That is, ccp. →C+2CN■? C+FezOs +3CP. t →2 F e
C Q 3+ 3 C○ And when the temperature exceeds 1900°C. CCl.
The temperature is changed to ccg■Fz, and the scouring process is continued for 4 hours or more at a temperature of 2500°C or higher. During the cooling process, flancing with an inert gas such as nitrogen or argon is continued to prevent back diffusion of impurities and remove halogen.

The purity of graphite obtained in this high purity treatment process is 99
．． It becomes 95wL% or more. That is, the impurity is 0.05-t
% or less.

The inventor of the present invention is. In order to increase the purity of the graphite used in graphite brushes, in addition to the high-precision treatment process described above, the graphite is refined using the following method. A graphite brush was manufactured and tested by applying it to a motor.

(i) Physical scouring flotation is used to separate impurities and graphite by utilizing physical and chemical differences on the surface of solid particles, and particles of approximately 300 μm or less are targeted. This is because graphite can be sorted by bubbles.
Put graphite powder into oil and bubbles. It was collected by floating it on air bubbles. In this case, a purity of 98% or more and less than 99.5% can be obtained.

Therefore, it contains about 0.5% to 2.0% as impurities. (ii) Chemically treated impurities contained in graphite are dissolved with a highly concentrated acid-5 alkaline solution. At the same time, heating (160" to 170'C) and pressure (5 to 6 atmospheres) are applied. This processing method is called the autoclave method, and the main reaction is considered to be as follows. Good. That is, FetOs + 6 H Cl → 2 Fe C Q s + 3 Hz 02SiO
．． +4NaOH-* 2 NazS i O* + 2 Hg ○ In the case of this treatment, a purity of 99% or more and less than 99.95% is obtained. Therefore, it contains impurities of about 0.05% or more and about 1.0%.

In this way, the carbon brush according to the present invention is produced by applying the graphite raw material refined through the high purity treatment step 2l to the binder treatment step 22' shown in FIG. 1(B). As mentioned at the beginning, for example, 0.1 wt% of conductive hard carbide with a particle size of 50 microns or less
or 15. O wt% is added to the binder to solidify the graphite powder. Therefore, the metal graphite brush according to the present invention manufactured through the subsequent processing steps 23 to 26 shown in FIG. 1(B) not only has excellent rectifying properties and wear resistance. It can also be made to have excellent conductivity.

Figure 3 shows the manufacturing process shown in Figure 1 (B). In the case where no additives are mixed into the binder in the binder treatment step 22' for the graphite raw material refined to a purity of 99.95% through the high purity treatment step 21, that is. In the case of no additives, oxides (e.g. Sing, Af203+Fe
20=, MnO, MgO, T i O, silicate, etc.) and a conductive carbide were added thereto. Experimental results data of a small motor using each carbon brush are shown.

In this experiment, each brush was tested for up to 80 hours. In this case, when oxides or carbides were added, the particle size was 50 microns or less and the amount added was 3 wt%.As shown in Figure 3, in an 80-hour test, The wear rate is 100%. The percentage was 33% for those with oxide addition, and 19% for those with carbide addition. Therefore, the wear resistance can also be increased by adding carbide.

Figure 4 shows the results for those to which carbide has been added (the particle size,
50 microns or less), and the test results are shown to see the change in the degree of wear when the amount added is changed.

In addition. In this case, 10 brushes containing carbide were manufactured. Tests were conducted for a maximum of 80 hours, and the x mark in the figure indicates the elapsed time when the vehicle became inoperable.

As shown in the same figure, when the amount of 9 carbide added is 0.5 wt%, the wear degree is 32% after 80 hours, but it is 21.0 to 15.
The degree of wear is relatively low up to O wt%, 20 wt% to 26 st%. However, at 20-t%, the wear of the commutator becomes extremely high, so the small motor is stopped.

From this, the amount of carbide added is 1.0 to 15. OwL
% is preferred.

Figure 5 is. The amount of carbide added is kept constant (3-t%).
It shows the results of a wear test when the particle size was changed.

As shown in the figure, the wear rate is 22% after 80 hours for particles with a particle size of 50 μm or less, and 2% for particles in the range of 50 to 74 μm.
0%. In the range of 105 to 149 ξ microns, it becomes 30%, and the average stopping time of the motor decreases to 53 hours, and furthermore, in the range of 149 to 174 microns, the degree of wear increases rapidly and almost all the motors become inoperable ( average 38 hours)
, unsuitable.

Based on the experimental results explained above, the particle size and amount of carbonized particles to be added were determined, and these values were set at 0.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 ton size type type type type type type type type form type type type form type form 50 tonnes or less. lwt%~15. It is optimal to add it within a range of Owt%.

In this example, an example was described in which carbide was used as a wear-resistant and conductive material. The wear-resistant and conductive material is not limited to carbides, but nitrides, borides, and silicides can also be used. The same effects as in the case of the carbide can be exhibited. Further, even if two or more of the above-mentioned carbides, nitrides, borides, or silicides are mixed together, the same effect can be obtained.

〔Effect of the invention〕

As stated above, in the present invention. In the high purity treatment step 2L shown in FIG. 1(B), the purity of the graphite raw material is increased to 99.
95% or more (therefore impurities are 0.05-t% or less)
Since this is a so-called pre-processing process, in which the process is carried out after the process is carried out, the rectification characteristics are improved, and at the same time, in the binder process 22'. A wear-resistant and conductive material with a particle size of 50 microns or less is added to the binder at an O. l
By adding wt% to 15.0 wt%, a metal graphite brush with improved wear resistance and conductivity can be realized.

[Brief explanation of the drawing]

Figure 1 (A) is a diagram of the principle structure of the metal graphite brush of the present invention.
FIG. 1(B) is an explanatory diagram of the manufacturing process of the metal graphite brush of the present invention. Figure 2 is a conceptual diagram of the refining furnace used in the high-purity treatment process of the present invention, and Figure 3 shows the case where no additives are added to the binder. In the case of oxide addition. Figure 4 is the experimental result data when testing the degree of wear of the brush in the case of carbide addition. The figure shows the experimental result data when testing the degree of wear when the amount of carbide added is constant and the particle size is changed, and Figure 6 shows the electron W4 micrograph of impurities contained in the graphite raw material. Each is shown below. In the figure, 1 is a commutator, 2 is a commutator piece, 3 is a rotating shaft, 4 is a carbon brush, 5 is a brush elastic body, 20 is a graphite raw material,
21 is a high purity treatment process, 22' is a binder treatment process,
23 is the crushing and sieving process. 24 represents a metal powder mixing process, 25 represents a pressurizing process, and 26 represents a burning process.

Claims (1)

[Scope of Claims] (1) Used in a small motor that is equipped with a permanent magnet as a field and rotated by commutation through a commutator, and is formed by bonding graphite powder and has a commutator. In metal graphite brushes for small motors configured to slide, the graphite raw material is highly purified and the ash contained as an impurity in the graphite powder is refined to 0.05 wt% or less, while the binder Adding a wear-resistant and conductive substance with a particle size of 50 microns or less in the range of 0.1 wt% to 15.0 wt% during processing or mixing treatment with metal additives, followed by pressure molding and firing. A metal graphite brush for small motors featuring: (2) Wear-resistant and conductive material is TiC, ZrC, HfC
, VC, NbC, TaC, Cr_3C_2, MoC, W
The metal graphite brush for a small motor according to claim 1, which is a carbide containing one or more of C or the like as a main component. (3) Wear-resistant and conductive material is TiN, ZrN, NbN,
The metal graphite brush for a small motor according to claim 1, which is a nitride containing one or more of TaN, Cr_2N, VN, etc. as a main component. (4) The wear-resistant and conductive material is Ti
B_2, ZrB_2, NbB_2, TaB_2, CrB
, MoB, WB, LaB, VB_2, etc. or 2
The metal graphite brush for a small motor according to claim 1, which is a boride containing at least one species as a main component. (5) Wear-resistant and conductive substances are TiSi_2 and ZrSi_
2, NbSi_2, TaSi_2, CrSi_2, Mo
The metal graphite brush for a small motor according to claim 1, which is a silicide whose main component is one or more of Si_2, WSi_2, etc. (6) Used in a small motor that is equipped with a permanent magnet as a field and rotated by commutation through a commutator, and is formed by bonding graphite powder and configured to slide on the commutator. The method for manufacturing a metal graphite brush for a small motor includes a high-purity treatment step of refining a graphite raw material using a substance that liberates halogen in a high-temperature inert gas atmosphere, and graphite powder that has undergone the high-purity treatment step. a binder treatment step of solidifying with a binder; a mixing treatment step of adding and mixing metal powder after crushing and sieving the graphite material solidified with the binder; and pressurizing the mixed powder. a pressure molding step, and a firing step of firing the pressure molded product, and at the same time, in the binder treatment step or the mixing treatment step, abrasion resistant and electrically conductive particles having a particle size of 50 microns or less are carried out. 0.1wt% to 15.0wt of substance powder
A method for manufacturing a metal graphite brush for a small motor, characterized in that the metal graphite brush is manufactured by adding the metal graphite brush in a range of %.