JP2004143536A - Method for manufacturing rolling slide member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a rolling slide member capable of realizing good manufacturing efficiency and of suppressing a manufacturing cost while assuring machinability having no problems for practicable use. <P>SOLUTION: An intermediate blank is first fabricated by hot forging a blank consisting of high carbon steel. The intermediate blank subjected to a normalizing treatment, having a metallic structure of a substantially pearlite single phase set to ≤1.5 μm in the maximum thickness of cementite existing between pearlite particles is manufactured by subjecting the hot forged intermediate blank to the normalizing treatment. The intermediate blank subjected to the normalizing treatment is subjected to turning treatment and further to hardening and tempering, finishing treatment, etc. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a rolling sliding member in which rolling contact, sliding contact, or both contact occurs with a mating member such as a bearing ring of a bearing, a cam follower roller, and a cam surface member of a one-way clutch.
[0002]
[Prior art]
In general, a bearing ring or the like of a rolling bearing is formed by subjecting a material made of bearing steel to finishing such as forging, heat treatment, turning, quenching and tempering, cutting, and polishing. The heat treatment is as follows: (1) In order to eliminate unevenness in the metal structure of the material made of bearing steel, a normalizing process (heating process) of heating at an austenitizing temperature is performed, and then the material is softened and processed. In order to facilitate this, an annealing treatment (annealing treatment) in which heating is performed at a recrystallization temperature is performed, or in some cases, an annealing treatment is performed without performing a normalizing treatment (see Non-Patent Document 1). By such an annealing treatment, in the metal structure of the material made of the bearing steel, hard cementite particles are finely and uniformly dispersed in the ferrite ground, and the machinability is improved.
[0003]
[Non-patent document 1]
Kozo Seto, Vol. 9, Steel for Bearings, Japan Iron and Steel Association, December 27, 1999, p. 59-62
[0004]
[Problems to be solved by the invention]
However, the annealing treatment usually requires a long time of 5 to 30 hours to cool the furnace after heating and holding at 700 to 800 ° C., so that there is a problem that the production efficiency is low and the production cost is high.
[0005]
The present invention has been made in view of such circumstances, and while ensuring machinability without practical problems, realizing good manufacturing efficiency and further reducing the manufacturing cost of a rolling sliding member. Its purpose is to provide a manufacturing method.
[0006]
[Means for Solving the Problems]
The method for manufacturing a rolling sliding member according to the present invention is a method for manufacturing a rolling sliding member made of a heat-hardened high-carbon steel, which makes a rolling contact or a sliding contact or a contact including both contacts relatively with a mating member. In this method, a high carbon steel material is hot forged to produce an intermediate material, and this hot forged intermediate material is subjected to normalizing treatment to maximize the cementite existing between the pearlite particles. Producing a normalized intermediate material having a metal structure of a substantially pearlite single phase having a thickness set to 1.5 μm or less, and performing a turning process on the intermediate material after the normalization process; (Claim 1).
According to the above configuration, since the normalizing process is performed so that the metal structure to be subjected to the turning process becomes substantially a pearlite single phase, a normalized intermediate material whose machinability does not pose a practical problem is obtained. can get. This eliminates the need for a long-time annealing treatment, thereby improving the production efficiency and reducing the production cost. Further, high carbon steel having a carbon content exceeding 0.5% by weight (hereinafter abbreviated as “%”) and containing a large amount of hard proeutectoid cementite was treated, and the annealing time was particularly long. The improvement effect is particularly high.
Here, “substantially pearlite single phase” means that the maximum thickness of cementite existing between pearlite particles is set to 1.5 μm or less, and that the pearlite particles consist of only pearlite particles according to a 400 × optical microscope observation. It depends.
[0007]
In the above method for manufacturing a rolling sliding member, it is preferable that, as the normalizing process, a process of heating and holding at 750 to 830 ° C. and then cooling at a rate of 10 ° C./sec or less (claim 2). According to such a treatment, a metal structure of substantially pearlite single phase is ensured. The heating and holding time is preferably about 0.5 to 2 hours for a race of a normal rolling bearing.
[0008]
In the above method of manufacturing a rolling sliding member, it is preferable to use, as the hot forged intermediate material, a material in which a maximum thickness of cementite existing between pearlite particles is set to 10 μm or less (Claim 3). . According to the above configuration, the cementite existing between the pearlite particles can be substantially eliminated by the above normalizing treatment to form a pearlite single phase.
[0009]
In the above method for manufacturing a rolling sliding member, it is preferable to use, as the hot forged intermediate material, a material in which the particle size of pearlite is set to 50 μm or less (Claim 4). According to the above configuration, the cementite existing between the pearlite particles can be substantially eliminated by the above normalizing treatment to form a pearlite single phase.
[0010]
In the above method for manufacturing a rolling sliding member, it is preferable that the hardness of the intermediate material after the normalizing treatment is 30 or less HRC (claim 5). According to the above configuration, it is possible to ensure machinability with no practical problem, and therefore, it is possible to perform the turning process with higher accuracy.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a process chart showing a method for manufacturing a rolling sliding member according to an embodiment of the present invention. According to this manufacturing method, first, bearing steel (SUJ2, composition: carbon 1.01%, silicon 0.24%, manganese 0.36%, nickel 0.04%, 1.46%, molybdenum 0.01% The remainder is made of iron), and hot forging is performed on this material at about 800 to 1200 ° C. to produce a hot forged intermediate material having a surface hardness of about HRC40.
FIG. 2 is a cross-sectional view schematically showing a metal structure of the obtained hot-forged intermediate material observed with an optical microscope of about 400 times. This metal structure is composed of pearlite particles 1 and proeutectoid cementite 2 existing between the particles 1. The maximum thickness of the proeutectoid cementite 2 (the maximum linear distance between the particles 1) is preferably set to 10 μm or less, more preferably 8 μm or less. This is because if the maximum thickness of the proeutectoid cementite is small, the pearlite single phase can be substantially formed by the normalizing treatment described later, and as a result, good machinability can be realized. Further, the average particle diameter of the pearlite particles 1 (1/2 of the sum of the maximum diameter and the minimum diameter) is set to 50 μm or less so that the cementite layer in the pearlite particles 1 that adversely affects machinability becomes thin. It is preferably set, and more preferably 40 μm or less.
[0012]
Next, as shown in FIG. 3, the obtained hot forged intermediate material is heated and held at 750 to 830 ° C. for 0.5 to 2 hours, and then air cooled at a rate of 10 ° C./sec or less. The intermediate material having a hardness of HRC 30 or less, preferably HRC 25 or less is prepared by performing the treatment. By such normalizing treatment, the proeutectoid cementite melts and becomes small, and the re-precipitated cementite does not grow large, and further another structure does not come out, so that the pearlite substantially becomes a single phase. It has a metal structure. The more preferable heating and holding temperature is 760 to 820 ° C. from the viewpoint of obtaining a better pearlite single phase. In addition, the heating holding time in the case of a normal rolling bearing is 0.75 to 1.5 hours from the viewpoint of obtaining a more homogeneous pearlite single phase. Further, a more preferable air cooling rate is 7 ° C./sec or less from the viewpoint of obtaining better martensite.
FIG. 4 is a cross-sectional view schematically showing a metallographic structure of the obtained intermediate material after the normalization treatment, which is observed with an optical microscope of about 400 times. This metal structure substantially consists of the pearlite particles 3. As described above, the pre-normalized intermediate material has a metal structure in which the very hard proeutectoid cementite that was present after hot forging has substantially disappeared and has become a pearlite single phase. It has machinability not inferior to the annealed intermediate material obtained by the treatment. The average particle diameter (1/2 of the sum of the maximum diameter and the minimum diameter) of the pearlite particles 3 is preferably set to 60 μm or less, more preferably 50 μm or less.
FIG. 5 is a cross-sectional view schematically showing a metallographic structure of the obtained intermediate material after the normalization treatment, which is observed with an electron microscope of about 1000 times. When observed at a higher magnification, the metallographic structure of the intermediate material after normalization treatment is composed of pearlite particles 3 and cementite 4 having a maximum thickness of 1.5 μm or less interposed between the particles 3, It can be said that hard cementite 4 does not substantially exist.
[0013]
Subsequently, the obtained intermediate material having been subjected to the normalizing process is subjected to a turning process using various turning tools, and processed into a predetermined shape. Here, as described above, the above-mentioned intermediate material having been subjected to the normalizing treatment has machinability having no practical problem, so that the intermediate material can be processed into a predetermined shape without impairing the life of the turning tool.
[0014]
Thereafter, quenching and tempering are performed according to a conventional method, and further, finishing treatment such as cutting and polishing is performed. Thus, a desired rolling sliding member can be obtained.
[0015]
The rolling sliding member obtained in this manner is not subjected to annealing treatment, and is subjected to turning treatment after performing normalization treatment in which heating, holding and cooling are specified under specific conditions, so that production efficiency is good. In addition, the manufacturing cost is low and the cost is low. Specifically, the annealing process after hot forging conventionally required 5 to 30 hours, but according to the present embodiment, the normalizing process can be completed at most about 2 hours, and as a result, 40 hours is required. The cost can be reduced by about%.
[0016]
The above-mentioned rolling sliding member can be used as various parts whose life is extended by contact including rolling contact, sliding contact, or both contact, for example, a bearing ring or a rolling element of a bearing.
[0017]
Although SUJ2 is used in the above description, the invention is not limited to this, and other bearing steel (such as SUJ3) or high carbon steel such as tool steel may be used.
[0018]
【The invention's effect】
As described above, according to the method for manufacturing a rolling sliding member of the first aspect, normalizing is performed so that the metal structure to be turned is substantially a pearlite single phase without performing a long-time annealing process. Since the treatment is performed, good production efficiency can be achieved while maintaining machinability with no practical problem, and the production cost can be kept low.
[0019]
In the above-mentioned manufacturing method, when performing the cooling process at a rate of 10 ° C./sec or less after heating and holding at 750 to 830 ° C. as the normalizing process, the metal structure of substantially pearlite single phase is surely obtained. It becomes. In addition, when the hot forged intermediate material has a maximum thickness of cementite existing between pearlite particles set to 10 μm or less, or a material in which the particle size of pearlite is set to 50 μm or less, The cementite which is present between the pearlite particles can be substantially eliminated by the above normalizing treatment to form a pearlite single phase. Further, when the intermediate material having been subjected to the normalizing treatment, the one having a surface hardness of HRC30 or less is used, it is possible to secure the machinability without any practical problem, and therefore, it is necessary to perform the turning treatment with higher accuracy. Can be.
[Brief description of the drawings]
FIG. 1 is a process chart showing a procedure of a method for manufacturing a rolling sliding member according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing a metal structure of a hot-forged intermediate material observed with an optical microscope of about 400 times.
FIG. 3 is an explanatory view showing normalizing processing conditions in the method for manufacturing a rolling sliding member according to one embodiment of the present invention.
FIG. 4 is a cross-sectional view schematically showing a metal structure of an intermediate material after normalization observed by an optical microscope of about 400 times.
FIG. 5 is a cross-sectional view schematically showing the metal structure of the intermediate material after normalization observed with an electron microscope of about 1000 times.
[Explanation of symbols]
3 perlite particles 4 cementite

Claims (5)

A method for manufacturing a rolling sliding member made of heat-treated and hardened high carbon steel, which has a relative rolling contact or a sliding contact or a contact including both contacts with a mating member,
Hot forging a material made of high carbon steel to produce an intermediate material,
This hot-forged intermediate material is subjected to normalizing treatment to form a normal pearlite single-phase metal structure in which the maximum thickness of cementite existing between pearlite particles is set to 1.5 μm or less. Produce processed intermediate material,
A method of manufacturing a rolling sliding member, wherein a turning process is performed on the intermediate material after the normalizing process. The method for manufacturing a rolling sliding member according to claim 1, wherein, as the normalizing process, a process of cooling at a rate of 10 ° C / sec or less is performed after heating and holding at 750 to 830 ° C. The method according to claim 1, wherein the hot forged intermediate material has a maximum thickness of cementite existing between pearlite particles of 10 μm or less. 4. The method for manufacturing a rolling sliding member according to any one of claims 1 to 3, wherein the hot forged intermediate material has a particle size of pearlite set to 50 µm or less. The method for manufacturing a rolling sliding member according to any one of claims 1 to 4, wherein the intermediate material after the normalizing treatment has a surface hardness set to HRC30 or less.

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