JP4264799B2 - Sintered oil-impregnated gear - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improvement of a gear that is widely used as a part of various devices ranging from various machinery and equipment to a high-precision device such as a personal computer or a printer, and has been conventionally known as a material having excellent productivity and dimensional accuracy. An object is to provide further versatility by using a binder and also having low noise characteristics.
[0002]
[Prior art]
Not only gears, but also engine parts such as sprockets and oil pump rotors, transmission parts such as synchronizer hubs and retainers, as well as various transportation equipment parts such as pistons for outboard motors and parts for electric bicycles. Various mechanical structural parts having a lubricating function by forming a sintered body by compacting and sintering metal powder and impregnating the sintered body with machine oil or the like are already known. . Resin gears have also been developed to achieve low noise.
[0003]
[Problems to be solved by the invention]
However, since these products are only subjected to oil impregnation treatment on a sintered body manufactured according to the same standard as that for manufacturing a general sintered machine part having no oil impregnation function, the upper limit of the oil content is 15 at most. % Stop. Therefore, although it has some lubricity, it is not always sufficient, so there is a problem in quietness. Therefore, depending on the field of mechanical parts used, such as gears and motor bearings used as parts of acoustic equipment, for example. May not be suitable for use. Although resin gears have the advantage of low cost, they are inferior in dimensional accuracy and cannot be used for highly functional products, so post-processing is also attempted to increase dimensional accuracy. On the other hand, the usage is limited because it is expensive.
[0004]
[Means for Solving the Problems]
Therefore, in the present invention, among the metal sintered machine parts, the characteristics of gears that can be used for OA related equipment such as personal computers and printers, and that require low noise and quietness have been improved. Specifically, the invention of claim 1 uses a copper-based sintered material containing Cu: 5 (weight)% or more and containing a Cu component in the form of copper-coated iron powder. In addition, the present invention relates to a sintered oil-impregnated gear having an oil content of 18 to 25 vol%. In this case, it is increasingly used in general households due to the price reduction of personal computers and printers. In that case, it is a matter of course that the balance between durability and quietness required for business use is different.
[0005]
Furthermore, the invention of claim 2 relates to the sintered oil-impregnated gear according to claim 1 , wherein 5 to 12 (wt)% of tin is added to the amount of Cu. Furthermore, the invention of claim 3 relates to the sintered oil-impregnated gear according to claim 1 or 2 , wherein zinc of 10 to 40 (wt) is added to the amount of Cu.
[0006]
In the configuration of the gear in each case described above, the durability required for the gear is maintained and the oil content (oil content) is sufficient, so that not only the lubrication characteristics but also the low noise performance is improved.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific contents of the present invention will be described based on examples. FIG. 1 shows an example of a gear according to the present invention. That is, this gear represents a general involute spur gear, and tooth portions 2 that protrude outward are protruded from the outer peripheral surface of the cylindrical wheel 1 at equal intervals in the circumferential direction. Regarding the material of the gear, various materials are selected depending on the application.
[0008]
In other words, in general, when priority is given to strength, ferrous sintered materials are required, and when priority is given to quietness, bronze sintered materials are required when both strength and quietness are required. A copper-coated iron-based sintered material is used. In addition, even when any of these sintered materials is used, it is necessary to ensure an oil content of a certain value or more in order to maintain lubricity.
[0009]
Oil content is related to wear resistance and gear life, and even if the oil content is low or conversely too high, it is difficult to obtain good lubricity. As described above, it is necessary to set the oil content within an appropriate range depending on the material of the gear selected according to the purpose of use of the gear. In this case, the oil content can be set by adjusting the filling amount (weight) of the raw metal powder in the mold for molding the gear.
[0010]
Furthermore, in the case of using an iron-based sintered material from the viewpoint of emphasizing strength as a gear material, it contains a small amount of Cu not only for maintaining the rigidity as a gear but also for ensuring the quietness of the gear. Is preferred. However, if the Cu content exceeds 5 (weight)%, the necessary and sufficient rigidity for the gear cannot be obtained. Accordingly, an iron-based sintered material having a Cu content of less than 5 (weight)% is preferable, and it is difficult to maintain sufficient lubricity and quietness when the oil content is 20 vol% or less. On the other hand, if it exceeds 25 vol%, it will adversely affect the rigidity of the gear, so it is desirable to set the oil content within the range of 21-25 vol%.
[0011]
Moreover, in order to combine both strength and silence, sufficient silence can be obtained even when using an iron-copper-based sintered material containing Cu: 5 (wt)% or more. In this case, since the surface hardness is low and the noise is low, the oil content can be kept somewhat lower than when using an iron-based sintered material of less than Cu: 5 (weight)%. If the ratio is less than 18 vol%, it is difficult to obtain sufficient lubricity as planned by the present invention. Conversely, if the ratio exceeds 25 vol%, the rigidity of the gear is adversely affected. % Must be set within the range.
[0012]
Furthermore, in this case, when tin or zinc is added to the amount of Cu described above, the strength, hardness and wear resistance of the gear can be increased. Specifically, in the case where tin is added, if the amount is less than 5 (weight)% with respect to the amount of Cu, there is not much effect, and conversely if it exceeds 12 (weight)%, the gear is too hard and brittle. Absent. Therefore, the amount of tin added to the amount of Cu is preferably in the range of 5 to 12 (weight)%.
[0013]
In addition, when zinc is added, if the amount is less than 10 (weight)% with respect to the amount of Cu, the effect is not so much. On the other hand, if it exceeds 40 (weight)%, the strength as a gear is deteriorated. Accordingly, it is desirable that the amount of zinc added relative to the amount of Cu be within the range of 10 to 40 (weight)%.
[0014]
Further, in the case of using a bronze-based sintered material in order to give priority to quietness, there is a problem that the strength is insufficient if Sn: less than 9 (weight)%, and conversely, Sn: 11 (weight)% is exceeded. In this case, it is desirable to set Sn within the range of 9 to 11 (weight)%, and in this case, when the oil content is less than 20 vol%, sufficient lubricity is obtained. In addition, even if it exceeds 25 vol%, there is a problem in strength. Accordingly, the oil content in this case is preferably set within the range of 20 to 25 vol%.
[0015]
Furthermore, except when using a bronze sintered material, when using an iron-based sintered material, the contained Cu component can also be contained in the form of copper-coated iron powder, thereby further improving quietness and corrosion resistance. You can also.
[0016]
【Example】
[Test data of various sample gears]
Sample type 0 to 2000Hz 2000 to 4000Hz 4000 to 6000Hz
Sample 1 8.92 11.52 5.24
Sample 2 9.34 14.04 6.76
Sample 3 8.57 10.52 6.05
Sample 4 8.69 10.20 6.16
Sample 5 8.34 11.22 6.34
(Unit: dBm)
Note 1: Sample 1 = Resin gear sample 2 = General-purpose gear (prefabricated gear)
Sample 3 = Copper-coated iron-based sintered gear (product of the present invention)
Sample 4 = Tin-added sintered gear (product of the present invention)
Sample 5 = Zinc-added sintered gear (product of the present invention)
Note 2: Oil sample used 1: Kinematic viscosity (40 ° C.) added to 100 mm 2 / s Thickener added Samples 2 to 5: Kinematic viscosity (40 ° C.) 68 mm 2 / s
[0017]
As described above, a conventional resin gear (sample 1), an existing iron gear (sample 2), a sintered gear (sample 3) according to the present invention, and a tin-added sintered material according to the present invention. When a gear (sample 4) and a zinc-added sintered gear (sample 5) which is also the product of the present invention were prepared and tested for their characteristics, sample 1 had a value at 0 to 4000 Hz compared to samples 3, 4 and 5. Although it is high but low at 4000 to 6000 Hz, the sound is low and difficult to hear. As a result, the noise is the lowest, but it has sufficient strength and hardness as a gear. However, there is a problem in terms of versatility.
[0018]
Further, it was found that Sample 2 was able to maintain the lubricity for the time being, but the noise was loudest and the practicality was lacking in terms of quietness. However, it was found that Sample 3 not only can maintain sufficient lubricity, but is particularly excellent in terms of quietness. In Samples 4 and 5, it was found that the strength, hardness and abrasion resistance as a gear can be further improved, and sufficient lubricity and quietness can be maintained.
[0019]
【The invention's effect】
As described above, the gear of the present invention is a gear using an iron-based sintered material, an iron-copper-based sintered material, or a bronze sintered material, and the oil content of each gear is within a certain range as described in each claim. Since all of them are set so as to be within, both of them maintain not only inferior durability as compared with conventional products, but also sufficient lubricity is obtained, in particular, excellent quietness, acoustic equipment and A wide range of versatility is possible for OA related equipment.
[0020]
Furthermore, regardless of whether it is an iron-based sintered material, an iron-copper-based sintered material, or a bronze sintered material, the strength, hardness and abrasion resistance as a gear can be achieved by adding a certain amount of tin or zinc to the amount of Cu. Abrasion can be increased. Moreover, since the surface is covered with copper by using a copper-coated iron-based sintered material, the effects of silence, corrosion resistance, strength, and wear resistance can be further enhanced.
[Brief description of the drawings]
FIG. 1 is an enlarged longitudinal sectional view showing an example of a gear according to the present invention.
[Explanation of symbols]
1 Wheel 2 Gear

Claims (3)

A sintered oil-impregnated gear using Cu: 5 (weight)% or more and using an iron-copper-based sintered material in which the Cu component is contained in the form of copper-coated iron powder and having an oil content of 18 to 25 vol%. The sintered oil-impregnated gear according to claim 1 , wherein 5 to 12 (wt)% of tin is added to the amount of Cu. The sintered oil-impregnated gear according to claim 1 or 2 , wherein 10 to 40% (by weight) of zinc is added to the amount of Cu.

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