JP3822025B2 - Needle roller bearing with cage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a needle roller bearing with a cage.
[0002]
[Prior art]
For example as gear inner bearing used in a car or transmissions, but are used what is called a needle roller bearing with a cage without using the inner ring and outer ring, in such a cage with needle roller bearings, The race is used as a gear or a shaft installed on the bearing use object.
[0003]
Since the surface condition of these mating members is not controlled with high precision like the bearing race, wear called peeling is generated on the surface of the needle rollers in an environment where the lubricating oil is dilute and the lubricating conditions are severe. It can be said that the durability of the needle rollers is likely to be lowered, for example, because it becomes easier to do.
[0004]
[Problems to be solved by the invention]
On the other hand, conventionally, the surface hardness is increased by applying a special heat treatment to the surface of the needle roller, thereby obtaining a certain effect such as wear resistance. In order to improve the wear resistance, the surface hardness may be increased. However, if the surface hardness is increased too much, there is an adverse effect such as attacking the mating member. There is room for improvement here.
[0005]
In view of such circumstances, it is an object of the present invention to reduce the aggression of a mating member while suppressing damage to a rolling contact region over a long period in a needle roller bearing with a cage .
[0006]
[Means for Solving the Problems]
The rolling component of the present invention has an oil film coefficient Λ determined by a roller in rolling contact with the mating member, a minimum oil film (μm) of lubricating oil between the mating member and a surface roughness (Rq) of the mating member. (Μm / Rq) is used in a lubricated state in the range of 0.48 to 0.6, and at the same time, carbonitriding quenching treatment or nitriding quenching treatment is performed on the surface layer portion of these rollers to form charcoal / nitride. , A step of making the substrate of the surface layer portion high carbon and high nitrogen, and a step of managing the amount of retained austenite up to 0.5 mm in the depth direction by tempering in the range of 170 to 270 ° C. to 2 to 12% And a film having a modified surface roughness is formed by subjecting the surface of the roller to a phosphate film treatment.
[0009]
In short, in the present invention, a special heat treatment on the surface portion of the needle roller, also it is those subjected to phosphate conversion coating on the surface.
[0010]
In the special heat treatment described above, the residual compressive stress of the surface layer portion is increased and appropriately hardened by modifying the substrate of the surface layer portion of the high carbon steel material that is the metal base material of the needle rollers .
[0011]
Also, in phosphate coating treatment, the adhesion strength of the coating with excellent lubricating oil retention can be increased as much as possible by modifying the surface roughness and roughness of the surface of the high carbon steel after special heat treatment. It becomes easy to remain.
[0012]
As a result, the heat resistance, wear resistance, rolling fatigue life, and dimensional stability of the needle roller itself can be increased as much as possible, and the aggressiveness against the mating member can be reduced. Even in a dilute environment, the needle roller and the mating member are in contact with each other through the oil film, so that the metal base materials do not contact each other. For this reason, it becomes difficult to damage the surface of the needle roller .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described based on embodiments shown in the drawings.
[0014]
1 to 7 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view showing a needle roller bearing with cage (hereinafter abbreviated as needle roller with cage) , FIG. 2 is a sectional view schematically showing the surface of the needle roller, and FIG. FIG. 4 is a diagram showing the hardness distribution of needle rollers after special heat treatment, FIG. 4 is a diagram showing the amount of retained austenite in the surface layer portion of needle rollers after quenching by special heat treatment, and FIG. The figure which shows the amount of retained austenite in the surface layer part of the needle roller after returning, FIG. 6 is a longitudinal cross-sectional view of a testing apparatus, and FIG. 7 is a chart which shows a test result.
[0015]
In the figure, 10 is a needle roller with cage, 11 is a plurality of needle rollers, and 12 is a cage. This embodiment is characterized in that the surface layer portion substrate and the surface portion properties of the needle roller 11 are specified in the following forms.
[0016]
The needle roller 11 is made of a high carbon steel material as a base material, and a special heat treatment is applied to the surface layer portion thereof, and a phosphate film treatment is applied to the surface thereof. Examples of the above-mentioned high carbon steel materials include SUJ-2, SCr420H, SCM420H, SNCM220H, SNCM420H, SNCM815 in JIS standards, and 4320, 5120 in SAE standards.
[0017]
The special heat treatment is to increase the residual compressive stress by managing the amount of retained austenite in the depth direction in the surface layer portion of the metal base material.
[0018]
The phosphate film treatment is a broad expression including a manganese phosphate film treatment, a zinc phosphate film treatment, an iron phosphate film treatment, a tin phosphate film treatment, and any of these may be adopted. In this embodiment, an example in which a manganese phosphate film treatment is performed is given.
[0019]
Next, the special heat treatment and the manganese phosphate film treatment will be described in detail.
[0020]
First, in the special heat treatment, the surface layer portion of the needle roller 11 made of a high carbon steel material is subjected to a carbonitriding quenching treatment or a nitriding quenching treatment to form carbon / nitride, and at the same time, the substrate of the surface layer portion is made of high carbon, high nitrogen. And a step of performing a tempering process to manage the amount of retained austenite.
[0021]
The aforementioned carbonitriding quenching treatment or nitriding quenching treatment is performed for 3 hours in a sealed space containing carbon and nitrogen in a state where the ambient temperature is in the range of 780 to 900 ° C, preferably 830 ° C. The tempering treatment is performed for 2 hours in a state where the atmospheric temperature is in the range of 170 to 270 ° C, preferably 220 ° C.
[0022]
Thereby, the surface hardness can be set to HRC 60 to 65, the amount of retained austenite in a very shallow region of the surface layer portion can be set to about 12 to 2%, and the other regions can be set to 0%.
[0023]
By the way, the surface hardness and the amount of retained austenite were examined for each processing form, and will be described. Here, the embodiment products 1 and 2 and the comparative product are examined.
[0024]
The embodiment product 1 is JIS standard SUJ-2, and is tempered at 230 ° C. after being subjected to carbonitriding and quenching.
[0025]
The embodiment product 2 is JIS standard SUJ-2, and is tempered at 230 ° C. after being subjected to carburizing and quenching.
[0026]
The comparative product is JIS standard SUJ-2, which has been subjected to normal quenching and then tempering at 230 ° C.
[0027]
First, the hardness is as shown in FIG. However, only the comparative product has a substantially uniform hardness over the entire region in the depth direction from the surface.
[0028]
Further, the amount of retained austenite is about 40 to 30% in the region from the surface to a depth of 0.5 mm as shown in FIG. 4 in the stage after quenching, but after tempering, as shown in FIG. To about 12-2%. Only the comparative product has a substantially uniform amount from the surface to the entire region in the depth direction.
[0029]
Further, in the manganese phosphate film treatment, a manganese phosphate film treatment solution (an aqueous solution of a manganese phosphate compound) is used as disclosed in, for example, JP-A-6-159371. When this manganese phosphate coating treatment is performed, the surface of the needle roller 11 is formed with, for example, an indentation 20 that is independent from each other as shown in an exaggerated manner in FIG. A coating 21 made of is formed. This manganese phosphate film 21 is represented by chemical formula (Mn _1-X Fex) ₃ H ₂ (PO ₄ ) ₄ .4H ₂ O, and has a monoclinic crystal structure.
[0030]
In this embodiment, when performing the manganese phosphate film treatment, the surface condition of the metal base material to be treated and the film thickness and surface condition of the film 21 are set according to the conditions described in (1) to (4) below. It is managed to meet.
[0031]
(1) On the surface of the needle roller 11, 15 or more indentations 20 having a depth of 0.5 μm or more with a roughness center line as a reference (= 0) are provided independently per 1 mm width.
[0032]
(2) The parameter SK value of the surface roughness on the surface of the needle roller 11 is set to less than 0 and the parameter Rq value is set to 0.1 or more. As is well known, SK is used to see the bias of the surface roughness distribution. When this SK value is less than 0, it is a negative value so that the uneven distribution is an asymmetric distribution biased to the concave side. Surface condition. Rq is the root mean square roughness as is well known.
[0033]
(3) The film thickness of the film 21 is set to 5 μm or less.
[0034]
(4) The surface roughness parameter Rq of the film 21 is set to 1.5 or less, preferably 0.3 to 0.7.
[0035]
Next, the performance of the needle roller 11 that has been subjected to the above-described processing is examined using the test apparatus 50 shown in FIG.
[0036]
In FIG. 6, 51 is a drive shaft rotated by a motor (not shown), 52 is a driven shaft rotated by the drive shaft 51, 53 is a support base for the drive shaft 51, 54 is a support frame for the driven shaft 52, 55, 56 is a support bearing for the drive shaft 51, 57 and 58 are support bearings for the driven shaft 52, 60 is a drive sample fixed to the drive shaft 51, and 61 is a driven sample fixed to the driven shaft 52.
[0037]
In the test, the rotational speed of the drive shaft 51 is 1000 rpm, the radial load applied to the drive sample 60 and the driven sample 61 is converted to the maximum contact surface pressure to 2.25 GPa, and the operation time is 20 hours (hr). And The lubricating oil to be used is turbine oil VG32, and the minimum film thickness of the lubricating oil between the driving sample 60 and the driven sample 61 is managed to be 0.284 μm. The oil film coefficient Λ (μm / Rq) obtained from the minimum film thickness (μm) of this lubricating oil and the surface roughness (Rq) of the driving sample 60 described below is managed in the range of 0.48 to 0.6. Is done. This oil film coefficient is an index indicating the lubrication state, and the above-described specific numerical values are approximated to a general lubrication state of a needle roller with cage used as a bearing for a gear inner, for example, and are in an accelerated test state. I am considering.
[0038]
The driving sample 60 corresponds to a mating member to which the needle rollers 11 are in rolling contact. For example, the driving sample 60 is formed of a general JIS standard SUJ-2 whose surface hardness is set to HRC 61 to 62, and the surface roughness is set. The root mean square roughness (Rq) is set to 0.528 to 0.594.
[0039]
The driven sample 61 corresponds to the needle roller 11. For this driven sample 61, an embodiment product and comparative products 1 and 2 are prepared. In the embodiment product, for example, the surface hardness is formed according to a general JIS standard SUJ-2 set to HRC 61 to 62, and the coating film 21 is formed on the surface by the manganese phosphate coating treatment under various conditions. The conditions for this manganese phosphate coating treatment are as described above. Comparative product 1 is obtained by subjecting the metal base material only to special heat treatment, and Comparative product 2 is assumed that the metal base material is not subjected to special heat treatment or manganese phosphate coating treatment. .
[0040]
Then, the presence or absence of peeling is confirmed on the surface of the driven sample 61, and it is determined that the lifetime has been reached when peeling occurs. This peeling is a phenomenon in which micro-peeling with a depth of a few microns and a size of several tens of microns accompanied by a surface crack is generated microscopically. It is a phenomenon that becomes like peeling off.
[0041]
As a result, as shown in FIG. 7, the comparative product 1 was about 20 hours and the comparative product 2 was about 10 hours, while the embodiment product dramatically increased to 250 hours.
[0042]
As a result, the surface part of the rolling part such as the needle roller 11 is subjected to special heat treatment, and the surface roughness is specified as described above, and the surface is made of manganese phosphate. If the film 21 is formed, it can be said that the durability can be dramatically improved and a long life can be achieved.
[0043]
In the embodiment described above, the wear resistance of the needle roller 11 itself can be improved to reduce the aggression against the mating member, and the lubricating oil can be applied to the surface of the needle roller 11 even in a dilute environment of the lubricating oil. Since the oil film is formed without interruption, it is possible to prevent direct metal contact between the needle roller 11 and the mating member. Therefore, peeling damage and fatigue peeling on the surface of the needle roller 11 occur. Can be suppressed over a long period of time.
[0044]
In addition, this invention is not limited only to the said embodiment, Various application and deformation | transformation can be considered.
[0046]
In the above embodiment, an example in which the surface of the needle roller is subjected to the manganese phosphate coating treatment is given. In addition, the zinc phosphate coating treatment included in the phosphate coating treatment, which is a broad expression, iron phosphate A film treatment, a tin phosphate film treatment, or the like can also be used.
[0047]
【The invention's effect】
In the present invention, the heat resistance, wear resistance, rolling fatigue life, and dimensional stability of the needle roller itself can be increased as much as possible, and the aggression against the mating member can be mitigated. even dilute environment, because requires a needle roller and the mating member is a contact through the oil film to not contact the metal base metals, long-term damage such as peeling or fatigue flaking in the needle roller surfaces It becomes possible to achieve a long life, such as being able to suppress over a long period.
[Brief description of the drawings]
FIG. 1 is a longitudinal cross-sectional view of a needle roller with a cage according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the surface of the needle roller. Figure showing hardness distribution [Figure 4] Figure showing the amount of retained austenite in the surface layer part of needle rollers after quenching by special heat treatment [Figure 5] Residual part in the surface layer part of needle rollers after tempering by special heat treatment Figure showing austenite amount [Fig. 6] Longitudinal cross section of test apparatus [Fig. 7] Chart showing test results [Explanation of symbols]
10 Needle Roller with Cage 11 Needle Roller 20 Indentation 21 on Needle Roller Surface 21 Film on Needle Roller Surface

Claims (1)

The oil film coefficient Λ (μm / Rq) obtained from the roller in rolling contact with the mating member and the minimum oil film (μm) of lubricating oil between the mating member and the surface roughness (Rq) of the mating member is 0. .Used in lubrication range of 48-0.6,
At this time, a carbonitriding quenching process or a nitriding quenching process is performed on the surface layer portion to form carbon / nitride, and at the same time, the substrate of the surface layer portion is made high carbon and high nitrogen, and is baked in the range of 170 to 270 ° C. A special heat treatment including a step of managing the amount of retained austenite up to 0.5 mm in the depth direction to 2 to 12% by performing a back treatment,
A needle roller bearing with a cage, wherein the surface of the roller is coated with a film whose surface roughness is modified by a phosphate film treatment.

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