JPS6170220A - Roller bearing used in grease lubrication - Google Patents

Abstract

PURPOSE:To reduce the depth of a false impression, by a method wherein a carburized nitriding layer, having quantities of carbon nitride with high hardness being dispersed by a carburized nitrided hardening processing, is formed on the race surfaces of inner and outer wheels. CONSTITUTION:A carburized nitriding layer 3 is formed on race surfaces 2 and 5 of inner and outer wheels 1 and 4 of a bearing. Formation of the carburized nitriding layer 3 is such that, after a turning processing is applied on a bearing material, a carburized nitriding processing is applied on the surface of the bearing material by heating the bearing material in a carburized nitriding atmosphere. Subsequently, hardening and tempering in oil are applied on the material as usual, and the material is finish-ground in a given shape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention belongs to the technological division of rolling bearings used with grease lubrication. If the equipment is attached and transported in a non-rotating state, repeated vibrations during transport may cause dents in the raceways of the inner and outer rings that come into contact with the sheath rolling elements.
The normal rotation of the bearing may be hindered by producing abnormal noises and vibrations.The dents that occur at this time are called pseudo-indentations (7-all sprinnelling). The cause of this is that the grease sealed in the bearing is subjected to mechanical effects such as Jll breakage due to rotation during steady rotation of the bearing, and the oil retained in the thickener is
It exudes onto the raceway and rolling surfaces and exerts a lubricating effect, but
It is said that in a non-rotating state, the lubricating effect of the oil in the grease is not sufficient, and in that state, vibration causes repeated relative sliding between the rolling elements and the bearing ring, causing wear.

In the early stages of wear, wear begins with metal contact due to lack of lubricant, and then the wear powder becomes oxidized wear powder due to dispersion in the atmosphere, and this interposition accelerates wear. It is well known that the hardness, wear resistance, and impact resistance required for raceway rings are obtained through the selection of materials and quenching treatment. When using high carbon chromium bearing steel as the bearing material, it is coated with a # agent into the desired shape, quenched and tempered, and then HR (!) is applied uniformly to the center.
Harden to 60 to 63 ◇On the other hand, for tapered roller bearings that require impact resistance, or ffl#l, Cr
Ll o #:j Materials such as case-hardened steel are used, and these KIv charcoal, quenching, and tempering are performed to make the surface layer I
(Hardened to RO60-63, hardness of center part HRO30-63)
45 to give it tenacity (Kousobo Co., Ltd., published on April 20, 1980, "Rogashi Bearing", pages 86 and 87) 0 The invention attempts to solve the problem. Problem: The occurrence of the pseudo-indentations in rolling bearings is observed even in the above-mentioned bearing materials and in products that have been hardened.

To solve this problem, (1) add lubricant to IJ-
It is effective to change from lubricating oil to lubricating oil or to higher consistency (softer) grease, and (2) apply a large preload to the bearing to prevent the rolling elements and raceway from collapsing. It is known that

However, with oil lubrication, there is a restriction that sufficient measures must be taken to prevent oil leakage from the bearing, and increasing the consistency of the grease or increasing the preload load also risks shortening the life of the bearing, so it is not practical in practice. Countermeasures are not easy.

Means for Solving the Problems The present invention focuses on the fact that the above-mentioned pseudo-indentations are caused by wear due to metal contact, and the present invention has developed a system in which highly hard carbonitrides are uniformly coated on the raceway surfaces of the inner and outer rings through carburizing and nitriding quenching treatments. The gist of this bearing is a roller used for grease lubrication with a carbonitrided layer dispersed in a large amount.

The carbonitrided layer may have a depth of 0.3151 to 0.7 mm, and its hardness at the surface ranges from HRO63 to
66, internal HRO is about 61-64.

Reducing adhesion on the working raceway surface and improving Jll resistance reduces the amount of wear on the contact surface with the special rolling element, and the pseudo indentation depth can be reduced to about 50% of the conventional one.

Embodiment In FIG. 1, 1 is the inner ring of a tapered roller bearing, 2 is the raceway surface thereof, and 3 is the carbonitrided layer according to the present invention. 4 is its outer ring, and 5 is its raceway surface.

The fJz diagram shows an inner ring 6 of a ball bearing, and a carbonitrided layer 8 is also formed on the raceway surface 7 of the ball bearing. Although not shown in the figure, the raceway surface of the outer ring of the ball bearing 1 is also subjected to a similar carbonitriding and quenching process.

Experimental example Inner ring of tapered roller bearing φL45449/10 and ball bearing This is followed by oil quenching and tempering in the same way as normal high-carbon chromium bearing steel is sub-quenched, and then polished to the desired shape. A carbonitrided layer of m was formed. The hardness of the raceway surface is HRO64~6
5, and the internal hardness was HRO 62 to 63. 0 This carbonitrided layer has a hardness of 9 due to the alloying elements contained in the material and carbonitriding.
Carbon and nitrogen that permeate and diffuse from the surface to the inside become solid solutions in the base material, increasing the strength of the base material. At the same time, by forming a large amount of fine carbonitrides, highly hard carbonitrides are coated on the entire surface. 1 and fine carbonitrides are dispersed.
Due to the dispersion of f1K, the fiber structure is precisely suppressed.

As a result, the wear resistance was significantly improved, and the amount of wear due to opposing surfaces on the contact surface between the bearing raceway and the rolling elements, that is, the pseudo indentation depth, was significantly reduced.

FIG. 5 shows the microscopic structure of the distribution of carbonitrides in the carbonitrided layer in the embodiment of the present invention, and FIG.
The figure shows micrographs of the bearing raceway surface of a conventional product made of chrome case-hardened steel that has been heat-treated by carburizing, quenching, and tempering.

It is clear that the surface structure of the carbonitrided and quenched raceway surface of the present invention is extremely dense compared to the conventional product made by so-called sub-quenching shown in Fig. 6 and the case-hardened carburized product shown in Fig. 7. be.

The product according to the above example was subjected to a simultaneous IC pseudo-indentation test with the conventional product, and after the test, the depth of the indentation in the shaft bone and the increase in vibration of the bearing due to the occurrence of the indentation were compared.

Figures 3 and 4 show the results.

The results of the above comparison are as follows when looking at the ratio of the indentation depth and the ratio of the increase in bearing vibration in the example of the present invention, with the conventional product set as 1.

Here, the appearance of the pseudo indentation is done by repeatedly applying a vibration load in the radial direction of the bearing.The indentation depth after the test is determined by measuring the circular direction shape of the raceway with a shape measuring instrument. The comparison was made based on the maximum indentation depth.

The increase in vibration of the bearing was measured by measuring the vibration acceleration of the bearing when the bearing was rotated at 1800 rpm, and comparing the increase from the value before the test.Examples include inner and outer rings of tapered roller bearings and ball bearings. Although the example is given for the inner ring of 1, it can be applied to other types of bearings and the same effect as 1 can be obtained.

Effects Compared to conventional products, the roller bearing according to the present invention can reduce the depth of indentation caused by about 50% and the increase in bearing vibration, which is a direct functional deterioration caused by indentation, by about 50%. Rollers with excellent indentation performance and less occurrence of false indentations are highly effective as bearings.

[Brief explanation of the drawing]

Figure 1 is a sectional view of an embodiment of a tapered roller bearing;
The figure is a cross-sectional view of the inner ring of a ball bearing, Figure 3 is a comparison graph of the indentation depth between the example product and the conventional product, Figure 4 is a comparison graph of the increase in bearing vibration between the example product and the conventional product, and Figure 5. Figures 6 and 7 are micrographs of the hardened surfaces of the example product and the conventional product.
Medical diagram 3 (inner number) I L45449/10 ``6305 Figure 2 Figure 4 (inner circle) nL45449/10 ``6305 Procedure amendment (method) 1. Display of the case 1982 Patent Application No. 173497 2 Name of the invention Rolling bearing used in grease lubrication 3 Person making the amendment Relationship to the case Name of applicant (124) Koyo Seiko Co., Ltd. 4 Agent Showa November 27, 1959 6, Subject of amendment 7, Contents of amendment (1) In the specification, page 11, lines 9 to 10, ``Figures 5, 6, and 7...'' ” is corrected as follows. Record

Claims (2)

[Claims] (1) Rolling bearings used for grease lubrication, in which a carbonitrided layer with a large amount of highly hard carbonitrides dispersed over the entire surface is formed on the raceway surfaces of the inner and outer rings through carbonitriding and quenching. (2) Add a depth of 0.3 mm to 0.7 mm to the raceway surface after polishing of the inner and outer rings of high-carbon chromium bearing steel bearings.
A rolling bearing used in grease lubrication according to claim 1, in which a carbonitrided layer is formed (3) The surface hardness of the carbonitrided layer is HRO63-66. Rolling bearings used with grease lubrication as described in Section 2