JP2005172200A - Roller bearing cage - Google Patents

Abstract

A cage for a rolling bearing having excellent wear resistance and durability even under severe use conditions.
A cage 1 includes 0.12% to 0.20% carbon (C), 0.10% to 2.0% silicon (Si), 0.15% by weight%. It is formed by subjecting a steel material comprising a composite structure containing 2.5% or less of manganese (Mn) and martensite or bainite mixed in ferrite to carburization or carbonitriding after press forming.
[Selection] Figure 1

Description

  The present invention relates to a cage for holding rolling elements of a rolling bearing, and more particularly to an improvement of a rolling bearing cage formed by press forming a steel material.

A needle bearing used in an automatic transmission (A / T) of an automobile or the like incorporates a cage for holding a rolling element. Such a cage uses a high-strength brass or mild steel excellent in self-lubricity and seizure resistance, which causes an increase in material cost and processing cost. Therefore, a low-carbon steel plate such as SPCC material or SPCD material is used. It is formed by press molding. However, when a low carbon steel plate such as SPCC material is used as the cage material, seizure occurs at the contact portion with the rolling element when the rolling element is rotated at a high speed, and the cage may be damaged. In view of this, it has been proposed to improve the wear resistance and seizure resistance of the cage by carburizing or carbonitriding the cage material (see Patent Document 1).
JP 2001-49346 A

However, in the technique described in the above-mentioned document 1, since the carbonitriding temperature is low and the alloy component of the cage material is not considered, there is a possibility that the strength of the cage material is insufficient. In particular, in recent years, the use conditions of rolling bearings are becoming more and more severe due to the multi-stage A / T accompanying the reduction in fuel consumption of automobiles. Therefore, there is a cage that can cope with high-speed rotation and high load capacity of rolling bearings. It is desired.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rolling bearing cage that is excellent in wear resistance and durability even under severe use conditions.

In order to achieve the above object, a rolling bearing retainer according to the present invention comprises 0.12% or more and 0.20% or less of carbon, 0.10% or more and 2.0% or less of silicon, by weight%. , And 0.15% or more and 2.5% or less of manganese, and a steel material having a composite structure in which martensite or bainite is mixed in ferrite is formed by carburizing or carbonitriding after press forming. It is characterized by that.
In the present invention, when martensite is mixed in the ferrite, the volume ratio of martensite is preferably 50% or less. Further, when bainite is mixed in the ferrite, the volume fraction of bainite is preferably 50% or less.

  According to the present invention, 0.12% or more and 0.20% or less of carbon by weight%, 0.10% or more and 2.0% or less of silicon, 0.15% or more and 2.5% or less of manganese, And a steel structure composed of a composite structure in which martensite or bainite is mixed in ferrite is used as a cage material, and this cage material is subjected to carburizing or carbonitriding after press forming to form a cage. Therefore, it is possible to increase the strength of the cage without impairing the press formability of the cage material, so that it is possible to obtain a rolling bearing cage excellent in wear resistance and durability even under severe use conditions. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of a rolling bearing cage according to the present invention. The cage 1 shown in the figure is 0.12% to 0.20% carbon (C), 0.10% to 2.0% silicon (Si), 0.15% by weight%. Carburizing treatment after press forming plate steel (hereinafter referred to as “cage material”) composed of a composite structure containing at least 2.5% and up to 2.5% manganese (Mn) and martensite or bainite mixed in ferrite Alternatively, it is formed by carbonitriding.
Here, the reason why the lower limit value of the carbon content of the cage material is set to 0.12% by weight is that sufficient strength cannot be obtained when the carbon content is less than 0.12% by weight. Moreover, the reason why the upper limit of the carbon content of the cage material is 0.20% by weight is that when the carbon content exceeds 2.0% by weight, the weldability and formability of the cage material are lowered. .

  The reason why the content of Si contained in the cage material is 0.10 wt% or more and 2.0 wt% or less is as follows. That is, Si is an effective element as a deoxidizer for steel making, and if the addition amount is less than 0.10% by weight, the effect cannot be obtained, so the lower limit was made 0.10% by weight. Further, Si has an effect of increasing resistance to temper softening, and is an element effective for increasing the strength of steel. It is more preferable to add 1.0% by weight or more, but it is added exceeding 2.0% by weight. However, the effect is not only saturated, but hot workability may be reduced, leading to an increase in manufacturing cost, so the upper limit was set to 2.0% by weight.

  The reason why the content of Mn contained in the cage material is 0.15 wt% or more and 2.5 wt% or less is as follows. That is, Mn is an element effective as a deoxidizing agent or desulfurizing agent at the time of steelmaking, and since the effect cannot be obtained when it is added less than 0.15% by weight, the lower limit was made 0.15% by weight. Further, Mn is an element effective for improving hardenability, and also effective for improving the strength of the base material. However, even if it is added excessively, the effect is not only saturated, but it may cause significant segregation during steelmaking, so the upper limit was set to 2.5% by weight.

  The reason why the cage material structure is a composite structure in which martensite or bainite is mixed in ferrite is as follows. In other words, when the cage material structure is made of, for example, a ferrite and pearlite structure, the plate-like carbide in the pearlite structure becomes coarse when the carbon content is high, and the accuracy of the punched surface during press molding of the cage material is increased. There is a possibility that the fatigue strength of the cage will be lowered. On the other hand, by mixing martensite and bainite in the ferrite, it is possible to prevent a decrease in fatigue strength due to poor accuracy of the punched surface, so in the present invention, the structure of the cage material is martensite in the ferrite. Or it was set as the composite structure which mixed bainite.

If the volume ratio of martensite or bainite mixed in the ferrite is too large, the yield ratio decreases and the formability of the cage material decreases, so if martensite is mixed in the ferrite, the volume ratio of martensite When the bainite is mixed, the volume fraction of bainite is preferably 50% or less.
The reason why the carburizing treatment or carbonitriding treatment is performed after press forming the cage material is that, as shown in Table 1, the wear resistance and durability of the cage are improved as compared with those not subjected to carburizing treatment or carbonitriding treatment. Because.

  “A to G” in Table 1 indicates main alloy components of the steel types shown in Table 2.

“I” in Table 1 indicates that the cage material is carburized under conditions of temperature: 790 ° C. to 850 ° C., gas atmosphere: RX gas + C ₄ H ₁₀ , and oil cooling and tempering (tempering temperature: shows the case of applying the 160 ° C. to 200 DEG ° C.), also "II" is a cage stock temperature: 790 ° C. to 850 ° C., atmosphere: under the condition of RX gas + C ₄ H ₁₀ + NH ₄ performs carbonitriding, It shows a case where oil cooling and tempering (tempering temperature: 160 ° C. to 200 ° C.) are performed after carbonitriding.

Further, “Abrasion amount” in Table 1 is load: P (radial load) / C (dynamic load rating) = 0.45, rotation speed: 10000 min ⁻¹ , test time: 200 hours, lubricant: ATF (Automatic Transmission Fluid) The result of having carried out the durability test of the cage under the conditions and measuring the wear amount of the cage pocket after the durability test is shown. In Table 1, “◯” indicates a case where no abnormality such as seizure was observed after the durability test, and “×” indicates a case where abnormality was recognized after the durability test.

  As described above, 0.12% to 0.20% C, 0.10% to 2.0% Si, and 0.15% to 2.5% Mn by weight%. The cage material is formed by performing carburizing or carbonitriding treatment after press forming a steel material composed of a composite structure that contains martensite or bainite in ferrite and does not impair the press formability of the cage material. In addition, since it is possible to increase the strength of the cage, it is possible to obtain a rolling bearing cage excellent in wear resistance and durability even under severe use conditions.

  In addition to the above-described C, Si, and Mn, elements that can improve workability and strength by refining the structure (for example, Ni, Cu, P, S, Cr, Mo, V, Ti, Ca, Al, O, Nb, B, Zr, REM, etc.) may be added to the cage material. Moreover, although the case where this invention was applied to the retainer of a radial needle bearing was illustrated in embodiment mentioned above, this invention is not limited to this, For example, for thrust needle bearings of a structure as shown in FIG. Of course, the present invention can also be applied to a cage.

It is a perspective view which shows one Embodiment of the cage for rolling bearings which concerns on this invention. It is a fragmentary sectional view of the holder | retainer used for a thrust needle bearing.

Explanation of symbols

  1 Cage

Claims (3)

  Holds rolling elements of a rolling bearing and is 0.12% to 0.20% carbon, 0.10% to 2.0% silicon, 0.15% to 2% by weight. Rolling bearings characterized by being formed by subjecting a steel material comprising a composite structure containing not more than 5% manganese and containing martensite or bainite in ferrite to carburization or carbonitriding after press forming Retainer.   The rolling bearing retainer according to claim 1, wherein the volume ratio of martensite mixed in the ferrite is 50% or less.   2. The rolling bearing cage according to claim 1, wherein the volume fraction of bainite mixed in the ferrite is 70% or less.

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