JPS62188728A - Production of bearing race - Google Patents

Abstract

PURPOSE:To efficiently produce a bearing race having superior mechanical properties by working a plain carbon steel into the body of a bearing race, building up a bearing steel on the part of the body forming a rolling surface with high density energy, hardening and tempering the bearing steel. CONSTITUTION:A plain carbon steel or a low-alloy steel such as S-Cr steel is worked into a blank 1 for an inner race. A bearing steel such as SUJ steel is built up on the part 2 of the blank 1 forming a sliding surface brought into contact with balls, that is, a rolling surface by plasma building up or other method to form a built-up part 3. This built-up part 3 is hardened, tempered and polished to form a rolling surface 4. Thus, an inner race 5 of a prescribed shape having improved fatigue strength is efficiently produced at a reduced cost.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of manufacturing a bearing race which is formed into a ring and rotated by sandwiching balls or rollers between the inner or outer rolling surfaces of the ring.

As is well known in the art, bearing races are constantly moved by poles and rollers in contact with each other, so that their rolling surfaces are subjected to repeated loads at high speeds.

Due to these usage conditions, the materials used for bearing races are required to have excellent wear resistance and high fatigue strength.
Bearing steel containing r is used after being quenched and tempered.

By the way, if even a small amount of defects such as non-metallic inclusions are present in this bearing steel, the fatigue strength will be significantly affected.

In order to eliminate such defects such as non-metallic inclusions, US Pat. No. 3,773,65 proposes a method for improving mechanical parts such as bearing races.

In this US patent, prior to heat treatment and finishing, the required surface areas are remelted using an electron beam in a vacuum to reduce nonmetallic inclusions and improve fatigue strength.

Problems to be Solved by the Invention However, when this method is applied to a bearing race, the material cost is high because the remelting process is performed on a conventional relatively expensive bearing race that is entirely made of bearing steel. In addition to this, the manufacturing cost increases due to this processing.

In addition, the process uses an electron beam as a heat source and is a true chamber process in which the bearing race is placed in a vacuum, so productivity is not good and the production cost is high due to this low production efficiency.
There is also the problem that ~ increases.

The basic purpose of the present invention is to solve the above-mentioned problems, and to provide a method for manufacturing a bearing race that can efficiently produce a bearing race that is inexpensive and has excellent fatigue strength.

Means for solving the problem, that is, the method for manufacturing a bearing race of the present invention is to apply high-density energy to at least a portion of a bearing race body made of ordinary carbon steel or low alloy steel where a rolling surface is to be formed. This is characterized by overlaying the bearing steel, and then subjecting the bearing steel to quenching and tempering.

Function: Before describing the function of the present invention, a detailed explanation of the present invention will be given.

The ordinary carbon steel that constitutes the bearing race body is not one to which special elements have been added for special purposes, but carbon steel used for general construction.

In addition, low alloy steel has special elements added for special purposes.
Machine structural steels such as SNC steel and SCr steel are used.

However, although the S-type steel is a chromium steel, for the purpose of the present invention, a steel with lower chromium than the bearing steel used for overlaying is used.

Bearing steel is steel with excellent fatigue strength and high chromium content.
For example, SUJ steel is used.

A laser, plasma, TIG arc, or the like can be used as a high-density energy source for overlaying this bearing steel.

Note that an electron beam can also be used as the high-density energy source. However, as described in the prior art section, electron beams require maintenance of a vacuum state and reduce work efficiency, so it is desirable to use a high-density energy source such as the one described above that does not require vacuum maintenance.

That is, according to the present invention, the bearing race body is made of relatively inexpensive ordinary carbon steel or low alloy steel,
Expensive bearing steel can be used only for contact parts with balls or rollers, that is, rolling surfaces, which require high fatigue strength, and therefore the material cost is significantly lower than if the entire bearing was made of expensive bearing steel. do.

Moreover, when building up by irradiating high-density energy, the high-density energy is stopped or moved, and the molten part due to the irradiation loses heat to the base material with a large mass and is rapidly cooled, so that the direction of solidification is from the inside. Directional solidification occurs toward the surface, pushing impurities such as non-metallic inclusions to the outermost surface, improving the quality of the inside of the build-up layer and further improving fatigue strength.

EXAMPLE Next, 11 experiments were conducted to evaluate the performance of the example of this invention.

(Experimental Example 1) JIS 5Cr440&14 was machined to produce a rough material for a Mori type bearing steel durability life test piece. A plasma build-up device was used on a predetermined surface of this rough material to build up a thickness of 2 m using powder equivalent to JIS 5UJ-2 under the following build-up conditions. Next, this was quenched and tempered, and roughly polished to give a predetermined test piece shape.

Conditions Welding current-voltage: 100A-26V Powder supply rate: 10]/min Carrier gas: 4.51/min Shielding gas: 25z/mrn Plasma gas: 3,51/min As a result, a thickness of 1.5m was obtained. A built-up part was obtained, and the amount of non-metallic inclusions in the built-up part was measured using the JIS method. As shown in Table 1, it was significantly less than that of ordinary bearing steel, and was almost at the same level as the comparative example described later. became.

Next, using this test piece, a Mori type bearing steel durability test was conducted under the following conditions.

Test load: 400 to 3f Stress repetition rate: 900 cycles/min Lubricating oil Nisbindl oil #60 As shown in Figure 3, the results show that the life, or fatigue strength, is significantly improved compared to ordinary bearing steel. It was found that the performance was equivalent to that of the comparative example.

(Comparative Example) As a comparative example, a test piece was manufactured as follows using the method shown in US Pat. No. 3,773,565.

Using JIS 5UJ-2 material (bearing steel), process a Mori-type bearing steel durability test specimen rough piece, place it in a specified place in a vacuum chamber, and vacuum the melted layer with an electron beam at 10'Torr. The remelting process was carried out so that the depth of the melt was 2#.

This was quenched and tempered and polished into a predetermined test piece shape. The thickness of the remelted layer was 1.5#, and the amount of nonmetallic inclusions and durability test were conducted in the same manner as in Example 1, and good results were obtained as shown in Table 1 and Figure 3. Obtained.

(Experimental Example 2) Next, a Mori type bearing steel durability test piece was manufactured in exactly the same manner except that TIG overlay was used instead of plasma overlay in Experimental Example 1. As a result, the amount of nonmetallic inclusions and the durable life were almost the same as in Experimental Example 1.

From the results shown in Table 1, Experimental Examples 1.2 and Comparative Examples have a smaller amount of residual non-metallic inclusions than ordinary bearing steel and are superior in fatigue strength.

(Example) Using JIS SCr440M, outer diameter φ80, width 20
Inner race rough material 1 of a ball bearing of size 1 was processed. A plasma overlay method is applied to a portion 2 of this inner race rough material 1 where a driving surface, that is, a rolling surface with respect to the balls, is to be formed.
IS SUJ, -2 powder was deposited under the following conditions to form a deposited portion 3.

Conditions Race rotation: 3ppm Filling current voltage: 120A-27V powder supply speed: 12g/min Carrier gas: 4.51/min Shielding gas: 2! M/min Plasma gas: 3.51/min Next, this was quenched and tempered, and the overlay portion 3 was polished to form a rolling surface 4 and finished into a predetermined shape to obtain an inner race 5.

As a result, the build-up thickness was approximately 1.5#, and the amount of non-metallic inclusions in the build-up part was measured according to the JIS method. A system: 00025% (
Cleanliness), C system: 0.005%, A+B+C system: 0.0
It was found that by using the same material as in Experimental Example 1, an inner lace with less nonmetallic inclusions and excellent fatigue strength could be manufactured.

In this example, plasma was used as a high-density energy source as in Experimental Example 1, but TIG arc may also be used as in Experimental Example.

Moreover, it goes without saying that the present invention can be applied not only to inner laces but also to outer laces.

As described above, according to the embodiments of the present invention, the amount of non-metallic inclusions can be significantly reduced compared to ordinary bearing steel, the fatigue strength has been improved, and the steel can be remelted in vacuum using an electron beam. The same fatigue strength as the treatment method can be obtained, and cheaper materials can be used compared to this method.

As described in detail, according to the present invention, the bearing race main body is made of ordinary carbon steel or low alloy steel, bearing steel is overlaid on at least its rolling surface using high-density energy, and then the bearing race body is made of ordinary carbon steel or low alloy steel. Since the steel is quenched and tempered, the main body can be constructed from relatively inexpensive materials, and bearing steel can be provided on the rolling surfaces where fatigue strength is required, which satisfies the required fatigue strength. In addition, the material cost can be reduced, and the melting with high-density energy results in directional solidification in the solid state, eliminating defects such as nonmetallic inclusions, and further improving mechanical properties, especially fatigue strength.

In addition, by using a high-density energy source that does not require maintenance of a vacuum state, bearing races can be produced efficiently, and this improvement in production efficiency can significantly reduce production costs.

Note that when using an electron beam that requires a vacuum method, an improvement in production efficiency cannot be obtained, but an effect of reducing material costs, that is, production costs can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the manufacturing process of an embodiment of the present invention, Fig. 2 is a perspective view showing an inner race similarly obtained in this embodiment, and Fig. 3 is a conventional bearing steel, an experimental example, and a comparative example. 2 is a graph showing the results of a durability test. DESCRIPTION OF SYMBOLS 1... Inner race rough material, 2... Part where a rolling surface is to be formed, 3... Built-up part, 4... Rolling surface, 5...
...Inner lace. Fig. 1 Fig. 3 Fuchimata A-Sashimi (xlO7)

Claims (1)

[Claims] It is characterized by using high-density energy to overlay bearing steel on at least the part where the rolling surface of the bearing race body made of ordinary carbon steel or low alloy steel is to be formed, and then quenching and tempering the bearing steel. A method of manufacturing a bearing race.