JP2000080446A - Induction-hardened rolling member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction-hardened rolling member excellent in cold drawability, having a long service life and high in wear resistance by dispersing the particles of Ti carbides and Ti carbonitrides into material steel and executing induction hardening. SOLUTION: In a rolling member used in such a manner that a rolling body 30 is arranged at an orbit member 10, the orbit member 10 contains, by weight, 0.40 to 0.90% C, 0.05 to 0.80% Si, 0.10 to 2.0% Mn, 0.05 to 0.50% Ti and <=0.03% N in the alloy components, at least the orbit face 11 of the orbit member 10 is subjected to induction hardening, also, Ti carbides and Ti carbonitrides having 5 to 100 nm average particle size are dispersed into the surface of the orbit member and the steel, and the hardness of the orbit face is controlled to >=59 HRC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling member typified by a linear guide bearing, a rolling bearing, a ball screw, a water pump bearing, a constant velocity joint, a hub unit bearing for an automobile, etc. The present invention relates to an induction-hardened rolling member which is excellent in wear resistance, has a long life, and is excellent in cold-drawing workability and can extend the life of a mold by induction hardening.

[0002]

2. Description of the Related Art Conventionally, medium carbon steels (C: 0.4
A technique of performing induction hardening to increase the hardness only on the surface of a component manufactured from 0 to 0.60%) to improve the static bending / torsion strength and the rolling contact strength is used. For such applications, steel materials such as JIS-S53C steel are mainly used. For example, Japanese Unexamined Patent Publication No. 6-57324 discloses that at least one material of an outer ring and an inner ring, which are bearing parts to be drilled, is C in a weight ratio;
0.50 to 0.65%, Si; 0.07 to 0.15%,
Mn: 0.05-0.35%, Cr: 0.25-0.5
There is disclosed a method for manufacturing a bearing for an automobile hub unit which is induction hardened and contains 5%, B; 0.0035% or less of each element as a main component.

[0003] Another technique is disclosed in Japanese Patent Laid-Open No. 5-5 / 1993.
No. 9486 discloses that C: 0.4 to 0.6%, Si;
1% or less, Mn: 0.2 to 0.4%, P: 0.015%
Hereinafter, S: 0.005 to 0.015%, Cr: 0.20
-0.50%, Mo; 0.08-0.30%, B;
0005-0.0030%, Ti; 0.02-0.05
%, Al: 0.01 to 0.05%, N: 0.006% or less, O: 0.002% or less, and Cr + Mo;
A cold forging steel excellent in induction hardenability and fatigue properties by using a material of 0.30 to 0.80% is disclosed.

Further, Japanese Patent Application Laid-Open No. 6-341432 discloses that
C: 0.56 to 1.0%: Si; 0.15% or less, M
n: 0.20 to 0.40%, Cr: 0.30 to 0.70
%, B: 0.0005 to 0.0035% by limiting the composition of the steel so that the hardness of the raceway member of the induction hardened guide rail is H without deteriorating the cold drawability.
A linear motion guide bearing having a v700 or more and improved wear resistance is disclosed.

[0005]

Generally, the steel material after induction hardening and tempering is harder as the carbon content of the steel material is larger. However, in the case of steel such as JIS-S53C, although a heat treatment is devised to obtain a surface hardness of about HRC59, the rolling fatigue life and wear resistance are insufficient. In addition, when the carbon content of the steel material is increased, the cold workability is reduced, so that the cost of the die in the cold drawing process is increased, and the productivity is deteriorated if the drawing speed is reduced by reducing the cost. is there.

[0006] With regard to the hub unit bearing disclosed in the above-mentioned JP-A-6-57324, C, Si, Mn, C
Since the alloy composition range such as r is defined, even if the annealing step after hot forging is omitted, the maximum value of the hardness does not exceed Hv230, and it is possible to perform drilling without impairing the tool life. There is a great advantage that the track member can be made hard enough to be practically used. However, a problem arises regarding the rolling fatigue resistance. That is, as shown in FIG. 5, the rolling raceway surface 2 of the induction-hardened hub unit 1 (mesh portion) wears due to a decrease in lubricating oil viscosity caused by intrusion of muddy water or foreign matter, and the life of the bearing is reduced. Harmful indentations are more likely to occur, and there is still room for improvement.

[0007] Further, regarding the steel for cold forging disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-59486, even if the hardenability is excellent, most of the steel is simply added by 0.02 to 0.05% of Ti. Since it is used to fix N required for containing B, a sufficient effect on wear resistance cannot be expected. Rather, there is a problem that the possibility of the existence of Ti-based nonmetallic inclusions having a size of several tens of μm that is harmful to the rolling fatigue life is increased.

In the case of the linear motion guide bearing disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 6-341432, the cold pullability is good, and the rolling fatigue is good as compared with the conventional steel. However, even if the wear resistance under the current use environment is sufficient, there is room for further improvement in the rolling fatigue resistance and wear resistance when the use environment deteriorates in the future.

SUMMARY OF THE INVENTION The present invention has been made to solve such an unsolved problem.
By dispersing Ti carbonitride particles and performing induction hardening, a rolling member that has been subjected to induction hardening with a surface hardness of HRc of 59 or more, which is excellent in cold drawing workability, has a long service life, and has high wear resistance. The purpose is to provide.

[0010]

According to a first aspect of the present invention, there is provided a rolling member having a rolling element which is disposed on a raceway member and rolls. At least one of C: 0.40 to 0.90%, Si; 0.05 to
0.80%, Mn; 0.10 to 2.0%, Ti; 0.0
5 to 0.50%, N; 0.03% or less, induction hardening is performed on at least the raceway surface of the raceway member, and Ti carbide and Ti carbonitride having an average particle size of 5 to 100 nm are coated on the surface of the raceway member. In addition, it is dispersed in steel, and the hardness of the raceway surface is HRC59 or more.

Further, the invention of the rolling member according to claim 2 is as follows.
In the rolling member subjected to the induction hardening according to the first aspect of the present invention, at least one of the raceway members has an alloy component of 0.05 to 2.0% Cr, Mo;
03-1.5%, Ni; at least one of 0.03-3.0%. According to a third aspect of the present invention, in the rolling member subjected to the induction hardening according to the first or second aspect, the alloy component of the raceway member further contains B: 0.0005 to 0.005. %
It is characterized by including.

Further, the invention of the rolling member according to claim 4 is as follows.
The rolling member subjected to induction hardening according to any one of claims 1 to 3, wherein the average particle diameter is 5 to 100 n.
m or more Ti carbides and Ti carbonitrides are dispersed in the raceway surface of the raceway member in a quantity of 100 or more / μm ² . According to a fifth aspect of the present invention, in the rolling member subjected to the induction hardening according to any one of the first to fourth aspects, the rolling member is a linear motion bearing.
The track member is a guide rail and a bearing.

Further, the invention of the rolling member according to claim 6 is as follows.
In the rolling member subjected to the induction hardening according to any one of claims 1 to 5, the surface hardness of the raceway surface of the rolling member is HRC59 to 65, and the hardness of a machined portion to be subsequently performed is HRB98 or less. It is characterized by having.

[0014]

Embodiments of the present invention will be described below. The rolling member of the present invention includes a track member having a raceway surface on which a rolling element rolls and a ball or roller that is a number of rolling elements, and refers to a member that performs a linear motion or a rotary motion. For example, linear motion guide bearings, various ball bearings and roller bearings, ball screws, water pump bearings, constant velocity joints, and hub unit bearings for automobiles, which are used by applying induction hardening to at least the raceway surface of the member. This is a typical rolling member. The present invention relates to a raceway member (a guide rail and a bearing of a linear motion guide bearing, a raceway ring of a rolling bearing, a ball) which is a component which is particularly susceptible to damage of the rolling members, and further determines the life of the rolling members. For the members constituting the raceway surface of the rolling member, such as the screw shaft and nut of the screw, the rolling fatigue life, wear resistance and cold pullability are further improved, and the workability and the long life are improved. A rolling member is to be obtained.

First, the reasons for limiting the alloy components in the rolling member according to the present invention will be described. [C; 0.40 to 0.90%] C is an element that imparts the hardness required as a rolling member, but if it is less than 0.40%, induction hardening is performed and the required tempering after tempering is performed. The track surface hardness HRC59 or more may not be secured. On the other hand, if the content exceeds 0.90%, the cold workability decreases. Therefore, the C content is set to 0.40 to 0.90%. [Si; 0.05 to 0.80%] Si is an element for improving the hardenability, and is expected to delay the structural change in rolling fatigue, but if it is less than 0.05%, the deoxidizing effect is sufficient. On the other hand, if it exceeds 0.80%, the cold workability is remarkably reduced, so that the Si content is 0.05 to 0.80%.
%. [Mn; 0.10 to 2.0%] Mn is an element effective for hardenability of steel, but if it is less than 0.1%, hardenability is insufficient, and if it exceeds 2.0%, cold working is performed. For this reason, the Mn content was set to 0.10 to 2.0% because the property was lowered. [Ti; 0.05 to 0.50%] Ti is finely dispersed in the form of Ti carbide (TiC) and Ti carbonitride (TiCN) in steel to improve wear resistance and rolling life. And an element that suppresses the coarsening of crystal grains during quenching. However, if it is less than 0.05%, most of them are Ti nitride (Ti nitride).
N), and the effect of fine TiC and TiCN is small. On the other hand, if it exceeds 0.50%, the cold workability decreases,
Further, TiN, which is an inclusion that reduces the rolling life, is likely to be generated, so the Ti content is set to 0.05 to 0.50%. [N: 0.03% or less] N combines with Ti to form Ti carbides and Ti carbonitrides, and has a large function of improving the rolling life by the dispersion strengthening effect of its fine dispersion, but the amount of N increases Then, the generation of large-particle Ti nitride increases,
As a result of the removal of N, the amounts of Ti carbide and Ti carbonitride decrease. Therefore, the N content is set to 0.03% or less. [Cr; 0.05 to 2.0%] Like Cr, Cr is an element that improves hardenability and promotes carbide spheroidization, and it is necessary to contain at least 0.05% or more. However, if the content exceeds 2.0%,
Since the carbide is coarsened and the cold workability is deteriorated, and the machinability may be deteriorated, the Cr content is 0.05 to
2.0%. [Mo: 0.03 to 1.5%, Ni: 0.03 to 3.0%]
%] Mo and Ni are both elements that are effective in improving toughness and rolling fatigue. However, if the amount is too small, the effect is not obtained. If the amount is too large, the effect is saturated.
3 to 1.5%, Ni; 0.03 to 3.0%. [B; 0.0005 to 0.005%] B is an element that improves the quenchability. However, if the content is less than 0.0005%, the effect is not sufficient. If the content exceeds 0.005%, the quenching effect is saturated. Therefore, the upper limit is preferably made 0.005%. [P: 0.02% or less. S: 0.02% or less. O;
[0016%] P is an element that lowers the rolling life and toughness, so its upper limit is made 0.02%. S is an element that improves machinability, but forms an sulfide-based inclusion that reduces rolling life by combining with Mn, so the upper limit was made 0.02%. O is an element that forms oxide-based inclusions in steel and reduces the rolling life, so the upper limit was made 0.0016%.

In the rolling member subjected to induction hardening according to the present invention, based on the above alloy components, at least C:
0.40 to 0.90%, Si; 0.05 to 0.80%,
Mn: 0.10 to 2.0%, Ti: 0.05 to 0.50
%, N: 0.03% or less. Then, fine Ti carbide and Ti carbonitride having an average particle size of 5 to 100 nm are dispersed on the surface of the inner ring in the alloy and in the steel. Here, Ti having an average particle size of 5 to 100 nm
The carbide (TiC) has a Ti carbide particle number of 1 μm.
It is desirable to disperse 100 or more particles per m ² (0.20 μm ² × 5 visual fields).

Next, the present invention will be specifically described by comparative tests performed on examples of the present invention and comparative examples. A linear guide bearing as shown in FIGS. 1 and 2 was selected as a rolling member of the subject. The guide rail 10 is a track member having a track groove (also referred to as a track surface) 11 which is a rolling groove of a rolling element on both side surfaces. A bearing 20 having a raceway groove 21 opposed to the groove 11 is fitted, and a number of rolling elements (steel balls) 30 circulating in the bearing 20 while rolling in the two raceway grooves 11 and 21 facing each other. A relative linear motion is performed through rolling.

The guide rail 10 and the bearing 20 of this linear motion guide bearing are trial manufactured using a steel material having an alloy composition shown in Table 1, and the workability in that case, the wear resistance of the assembled linear motion guide bearing, and This is a comparative study of rolling fatigue resistance. The alloy compositions of Examples 1 to 10 and Comparative Examples 1 to 9 are as shown in Table 1.

[0019]

[Table 1]

(A) Workability Test A guide rail 10 of a linear motion guide bearing was manufactured from test materials having the alloy compositions shown in Table 1. For this test material, Ti
Is dissolved in the matrix, 1150 to 135
Heating is performed at 0 ° C. to perform a solution treatment.
Perform normalizing at 050 ° C., spheroidizing annealing,
TiC was finely dispersed and precipitated. By subjecting the material to this soaking process, the size and abundance (dispersion state) of particles such as TiC and TiCN are determined.

Next, a test material (diameter: 40 mm × length: 5 m, steel bar) consisting of test materials having the respective compositions of Examples 1 to 10 and Comparative Examples 1 to 9 was used as follows. Cold drawing was performed in the same conditions under the same conditions.
Comparative Example 1 is based on JIS-S53C, and Comparative Example 2 is based on S3.
5C. The cold drawing process includes (1) piercing (the tip of the material is passed through the hole of the die), (2) low-temperature annealing,
A series of four steps of (3) forming a lubricant film (phosphate coating + metal soap coating) on the surface of the material, and (4) extracting the material, are rough, medium, and final. Material (a) whose cross section is elliptical as shown in FIG. 3 by repeating using each cemented carbide die.
Was made into a rail having a ball groove of a predetermined shape in (d) through the respective cross sections in (b) and (c). Then, the life of a die (die) was compared for each material. In the case of the guide rail of the linear motion guide bearing, since the cross-section is formed by the cold drawing, the evaluation of the cold workability of the alloy material is particularly important.

That is, in the finishing process in which dimensional accuracy is severe, after the number of withdrawn dies reaches 1000, the shape of the product is measured every 50 pieces, and the dimensional accuracy of the ball groove is determined to be poor due to wear of the inner surface of the die. The number of treatments when they became exhausted was examined. Then, the life ratio was calculated based on the life of Comparative Example 1 in which 2,000 pieces were processed. Table 2 shows the results.

[0023]

[Table 2]

As can be seen from the results in Table 2, Examples 1 to
No. 10 is a value whose die (die) life ratio is larger than that of Comparative Example 1 (corresponding to the conventionally used JIS-S53C steel), and has a cold drawing property equal to or higher than that of the conventional one. I have. Comparative Examples 2, 3, 4, and 7 are also better than Comparative Example 1, but the steel materials of Comparative Examples 5, 6, 8, and 9, which are outside the scope of the present invention, have too much C content, The life of the dies is comparative example 1 due to too much other alloy composition.
It was shorter and had poor cold drawing properties. (B1) Quenching hardenability Further, on each of the two side surfaces (rolling raceway surfaces) of each of the guide rails 10 having been subjected to the cold drawing process in which the ball grooves 11 are formed, a high frequency is applied under the following conditions. Quenching (moving quenching) and tempering (150 to 180 ° C.) were performed. By this induction hardening, the surface hardness HRC59 or more of the raceway surface 11 of the guide rail 10 can be achieved. Regarding Comparative Example 9, subduction quenching was performed at 840 ° C. instead of induction hardening, and then tempering treatment was performed at 160 ° C. By the way, the guide rail for the hardening of the tub hardly bends, and it is necessary to correct it in a later process, and the polishing man-hour is extra. [Quenching conditions] Frequency: 30 kHz Current: 10 A Cooling water flow: 35 l / min Voltage: 10 kV Feed rate: 8 mm / sec After heat treatment, the rail raceway surface of each guide rail 10 (ball groove 11 in FIG. 2). Was measured for surface hardness (HRC). The measurement was performed from the surface toward the inside as shown by the arrow G in FIG. The measured value, Rockwell hardness, is also shown in Table 2 above. In Examples 1 to 10, under the conditions of induction hardening, even when the depth reaches 10 mm, the HR
No decrease in hardness of C59 or less was observed, and it was good. (B2) Hardness of the surface not subjected to induction hardening (the surface other than the raceway surface) Further, in each of the guide rails 10 subjected to the cold drawing, the cross-sectional hardness of the surface other than the surface on which the ball groove 11 is formed was measured. . Table 2 shows the results. As compared with the surface portion of the ball groove 11 subjected to the induction hardening,
10, all of Comparative Examples 1 to 8 have low hardness. However,
For the hardness measurement at this time, a Rockwell hardness B scale (HRB, load 100 kgf, diameter 1/16 inch sphere) was used. In addition, as for the comparative example 9, the guide rail 10
Since the whole was soaked, the hardness of the portion of the ball groove 11 and the hardness of the portion other than the raceway surface became the same value. (B3) Drill hole processing performance test After the guide rail 10 that had been cold drawn was annealed and then induction hardened only in the portion of the ball groove 11, portions other than the ball groove 11 were subjected to FIG. ), Drilling of the bolt holes 12 was performed, and the service life of the working tools used at that time was compared. However, it is also possible to perform induction hardening directly without annealing after the guide rail 10 is cold drawn.

The processing conditions of the high-speed steel tool are as follows. Tool: SKH56 equivalent, 6.0D, TiN coating Cutting speed: 20m / min Feeding speed: 0.1mm / rev Lubricating oil: Water-insoluble cutting oil The life of a drill tool is determined until wear occurs on the cutting edge. Based on the number of drilling times, the high-speed steel drill was observed every 50 drilling holes after reaching 200 drilling numbers.
The results are shown in Table 2.

As a result of this test, in Examples 1 to 10, the tool life was 2.1 times or more as compared with the case of Comparative Example 1 (conventional example), and a long life was realized. This is because TiC and TiCN finely dispersed and deposited form a thin Ti coating film on the tool surface in the cutting process between TiN on the tool surface and the base material, thereby improving the life of the tool. Conceivable. Furthermore, since the steel material to which Ti is added is easily softened after the drawing process,
This is because processing becomes easy.

On the other hand, in Comparative Examples 2, 3, and 4, the tool life was extended as compared with Comparative Example 1, but C, Si, M
Since the addition amount of n was not sufficient, the time was shorter than that of the example. Further, in Comparative Examples 5, 6, 7, and 8, since the added amounts of C, Si, Mn, and Ti were large, the machinability such as peeling was poor, and the cutting resistance was low despite the low base material hardness. Increased, resulting in a tool life of 1 or less.

Further, in Comparative Example 9, although the amount of alloying elements was sufficient, the base metal hardness was H because of the soaking.
RC60, resulting in the shortest tool life.
Generally, for track members such as guide rails for linear motion guide bearings (linear guides) and screw shafts for ball screws, the raceway surface is first induction hardened, and then the mounting parts (bolt holes) and shaft end mounting parts are processed. There is a need to. This is because if the raceway surface is induction hardened, it may bend or twist in the axial direction more than the allowable amount. In such a case, the precision (dimensions, dimensions, Pitch).

Also, in the outer ring of the hub unit bearing shown in FIG. 5, it is necessary to remove the warp of the flange after induction hardening of the raceway surface and then process the mounting flange hole. That is, examples of these parts require cold drawing (or hot forging) → annealing → induction hardening of the raceway surface → machining such as drilling.

Therefore, in the present invention, (a) the surface hardness of the raceway surface is HRC59-65 by induction hardening.
(B) The hardness of the part to be machined other than the raceway surface is HRB 73 to 98. In (a), when the rolling contact fatigue life is less than HRC59, the rolling fatigue life is reduced. On the other hand, when it exceeds HRC65, cracks tend to occur on the raceway surface due to an external force (such as bending stress in the axial and longitudinal directions).

In (b), the lower limit of the HRB 73 is the minimum hardness when the material is not affected by heat. Originally, the lower the value, the better. In addition, if it exceeds HRB98, the tool life is shortened. (C) Abrasion resistance test Guide rail 10 and bearing 20 made of each steel of Examples 1 to 10 and Comparative Examples 1 to 9 as described above.
To assemble a linear guide bearing as shown in FIG.
Under the following test conditions, an abrasion resistance evaluation test was performed for each of three pieces. That is, as shown in FIG.
The two guide rails 10 provided with two are arranged in parallel, and the table 40 is placed on the two guide rails 10 so that the four bearings 20 are arranged at the four corners of the table 40.
A load W was applied to the center of the table from above, and the table 40 was reciprocated in a state where a reaction force RI = R2 = R3 = R4 equal to each bearing 20 was generated. (Wear test conditions) Rail length: 1.51 m Load: 655 kgf / bearing Test average speed: 24 m / min Lubrication: Grease lubrication (Albania No.
2) Reciprocating distance: 400 mm After the total traveling distance of the reciprocating motion was 6,400 km, the average wear depth of the raceway groove 11 was measured for each guide rail 10, and the average based on the average wear depth of Comparative Example 1 was measured. The wear depth ratio was calculated. As a result, as shown in Table 2, Example 1
And the average wear depth ratio of Comparative Examples 3 to 6, 8, and 9 are as follows:
The abrasion resistance was better than that of Comparative Example 1. This is considered to be the effect of the finely precipitated TiC. However, Comparative Examples 5, 6, 8, and 9 were inferior in mold life as described above. In Comparative Examples 3 and 4, the hardenability was poor, and the surface hardness was a low value of HRC57. From the above results, according to the steels of the compositions of Examples 1 to 10, in addition to being excellent in cold-drawing characteristics, it is possible to impart hardness exceeding HRC59 to the surface layer of the steel by induction hardening, and the linear motion guide bearing It is clear that when the rail is used, it is excellent in abrasion resistance and the life of the mold can be prolonged. (D) Rolling fatigue test with foreign matter mixed Muddy water and foreign matter enter the rolling raceway surface of a hub unit bearing or the like that has been subjected to high-frequency heat treatment, greatly affecting the rolling life. Therefore, a comparative test of rolling (contact) fatigue was performed in the following manner. That is, the embodiment shown in Table 1,
Using the steel material of the comparative example, a thrust life test specimen having a diameter of 60 mm was manufactured by induction hardening and tempering under the same conditions as described above. Note that Comparative Example 11 was manufactured by quenching after heating at 840 ° C and tempering at 160 ° C. The steel balls, using a steel ball that typically heat treated SUJ2, and organize the thrust life test specimen in conditions below the life of up to (thrust TP) is peeling a cumulative failure rate, L ₁₀ life (cumulative damage At a rate of 10%). The number of tests was 10. (Conditions of rolling contact fatigue test with foreign matter mixed in) Maximum hertz stress: 500 kgf / mm ² Test rotation speed: 1000 rpm Lubricating oil: Turbine oil in oil bath No. 68 Foreign matter: size 74 to 147 μm, hardness HV8
70, concentration 300 ppm The results are also shown in Table 2. As shown in Table 2, the lifetimes of Examples 1 to 10 are about 10 times or more longer than those of Comparative Example 1 (conventional example) and Comparative Example 7.
This is considered to be due to the dispersion strengthening of C and the surface hardness.

In Comparative Example 2, fine TiC was deposited, but since the surface hardness was 55 or less HRC, the rolling life was shorter than that of Comparative Example 1. Regarding Comparative Examples 3 and 4,
Since the hardenability was reduced and the surface hardness was HRC57, the life was longer than that of Comparative Example 1 due to the effect of fine TiC precipitation, but the life was not sufficient. In Comparative Examples 5 and 6, fine TiC was precipitated, and the life was significantly extended as compared with Comparative Examples 1 to 4. However, there is still room for improvement as compared with Examples. Further, in Comparative Example 8, fine TiC was confirmed, but at the same time, giant Cr-based carbides were also confirmed, which is considered to have led to a reduction in rolling fatigue life. In Comparative Example 9, 98 nm of TiC was finely precipitated, and the rolling fatigue life was at the level of the example. However, in order to further reduce the size of TiC, there was a limit in the soaking process other than induction hardening. Conceivable.
Also, in consideration of the cold workability, it tends to be much worse than Examples 1 to 10.

Therefore, the life ratio of the die (die) is calculated by
Judging from the results of the abrasion resistance test and (D) the rolling fatigue test with the inclusion of foreign matter, in the present embodiment, the average grain size in the steel subjected to induction hardening without deteriorating the cold workability was determined. By finely dispersing Ti carbide, Ti carbonitride and the like having a diameter of 5 to 100 nm, TiC, TiC
It is presumed that N prevents dislocation secondary slip as a barrier wall at the grain boundary. As a result, wear resistance is improved, indentations are less likely to be formed on the raceway surface, and rolling fatigue resistance is also improved.

[0034]

As is clear from the above description, according to the present invention, by adding 0.05 to 0.50% of Ti to a bearing steel subjected to high-frequency heating and quenching, the surface of the raceway member and the steel are reduced. Since Ti carbide and Ti carbonitride having an average particle size of 5 to 100 nm are finely dispersed therein, the wear resistance can be improved, and even when foreign matter enters, it is possible to suppress the formation of indentations on the raceway surface. As a result, there is an effect that the rolling life is extended.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a linear motion guide bearing subjected to a wear test.

FIG. 2 is a cross-sectional view taken along the line IIa-IIa of FIG. 1 and IIb-II showing an outline of an induction hardened portion provided to a component member of the linear motion guide bearing.
It is a sectional view taken on line b.

FIG. 3 is a cross-sectional view showing a change in a drawing shape in cold drawing of a material in a comparative test.

4A is a side view of a linear guide bearing for explaining a load method of a wear test, and FIG. 4B is a bottom view thereof.

FIG. 5 is a cross-sectional view of the hub unit bearing subjected to induction hardening.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Track member (guide rail) 20 Bearing 30 Rolling element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) F16C 29/04 F16C 29/04 33/58 33/58 (72) Inventor Nobuaki Mitamura Kusunuma Shinmei, Fujisawa City, Kanagawa Prefecture 1-5-50 Nippon Seiko Co., Ltd. (72) Inventor Yasuo Murakami 1-chome 5-150 Nippon Seiko Co., Ltd. No.5 50 Nippon Seiko Co., Ltd. (72) Inventor Shuhei Kitano 3007 Uichi Nakajima, Shizuma-ku, Himeji City, Hyogo Prefecture Inside Sanyo Special Steel Co., Ltd. Address Sanyo Special Steel Co., Ltd.

Claims (6)

[Claims] 1. A rolling member having rolling elements disposed on a raceway member, wherein at least one of the raceway members has a weight ratio C: 0.40-0.
90%, Si; 0.05 to 0.80%, Mn: 0.10
-2.0%, Ti; 0.05-0.50%, N: 0.0
At least 3% or less, induction hardening is performed on at least the raceway surface of the raceway member, and Ti carbide and Ti carbonitride having an average particle size of 5 to 100 nm are dispersed in the surface of the raceway member and in the steel. An induction-hardened rolling member having a hardness of at least HRC59. 2. A rolling member having a rolling element arranged and rolling on a raceway member, wherein at least one of the raceway members has an alloy component satisfying claim 1, and a weight ratio of Cr; 0.05 to 2.0%, Mo; 0.03 to 1.5
%, Ni: 0.03 to 3.0%. 3. A rolling member having a rolling element arranged and rolling on a raceway member, wherein at least one of the raceway members has an alloy component satisfying claim 1 and 2, and the weight ratio is B; A rolling member subjected to induction hardening, comprising 0.0005 to 0.005%. 4. Ti carbide having an average particle size of 5 to 100 nm, T
More than 100 carbonitrides are present on the raceway surface of the raceway member /
The induction hardened rolling member according to claim 1, wherein the rolling member is dispersed by μm ² . 5. The high-frequency hardened rolling member according to claim 1, wherein the rolling member is a linear motion bearing, and the track member is a guide rail and a bearing. 6. The surface hardness of the raceway surface of the rolling member is HRC59.
６５65, and the hardness of the machined part to be performed
The rolling member subjected to induction hardening according to any one of claims 1 to 5, having a B98 or less.