JP2013164093A - Manufacturing method of race for thrust needle bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a race for a thrust needle bearing which is excellent in processing performance, favorable in an yield of a material, and can be manufactured at low cost.SOLUTION: A manufacturing method of a race for a needle bearing comprises: a cutting process for cutting a wire rod or a round rod material of medium carbon steel to a prescribed length, and manufacturing a raw material; a forging process for forging the raw material and forming a flat-shaped first middle raw material; a grinding process for applying grinding processing to the surface of the first middle raw material and finishing it to a second middle raw material having a prescribed shape and surface roughness; a shearing process for press-processing the second middle raw material, thirling its center, and separating it to a ring-shaped third middle raw material and a thirled material 25; a burring process for erecting a flange at the internal peripheral edge side or the external peripheral edge side of the third middle raw material, and forming it to a fourth middle raw material having a prescribed shape; and a heat treatment process for applying hardening treatment such as carbonitriding, quenching and tempering to the fourth middle raw material, and finishing it as the race.

Description

  TECHNICAL FIELD The present invention relates to a method for manufacturing a thrust needle bearing race, and more specifically, various rotary machine devices such as automobile transmissions (including manual transmissions and automatic transmissions), compressors for various refrigerators such as car coolers, and the like. It is related with the improvement of the manufacturing method of the race which constitutes the thrust needle bearing which is built in and supports the thrust load added to the rotation support part.

  Thrust needle bearings are mounted on the rotation support parts of various rotating machinery devices that have rotating members such as rotating shafts that rotate while receiving thrust loads, such as automotive transmissions and refrigerator compressors. The thrust load applied to the member is supported. Conventionally, for example, those described in Patent Documents 1 and 2 are known as such thrust needle bearings. Among these, the structure of the thrust needle bearing described in Patent Document 2 and the shape of the race incorporated in the thrust needle bearing will be described with reference to FIGS.

  The thrust needle bearing 1 is formed by combining a plurality of needles 2 and 2 arranged in the radial direction and a pair of elements, each of which is U-shaped in cross section and entirely in a ring shape, in the middle. The cage 3 is configured to hold the needles 2 and 2 in a rollable manner, and a pair of races 4 a and 4 b that clamp the needles 2 and 2 from both sides in the axial direction of the cage 3. Each of these races 4a and 4b is subjected to stamping and bending with a press on an iron-based hard metal plate having sufficient hardness, such as high carbon steel, carburized steel, high carbon chromium bearing steel, and chromium molybdenum steel. Therefore, the whole is made in a ring shape. Of these, one of the races 4a (downward in FIG. 2), usually called an outer ring, has an annular race part 5a and a cylindrical flange part 6a formed on the outer periphery of the race part 5a over the entire circumference. It consists of. On the other hand, the race 4b on the other side (upper side in FIG. 2), usually called an inner ring, is composed of a ring-shaped race portion 5b and a flange portion 6b formed on the inner periphery of the race portion 5b over the entire circumference. .

  Each of the staking portions, each having a configuration as described above, at a plurality of circumferentially equidistant positions (four in the example shown in the figure) at the tip edges of the flange portions 6a and 6b of the races 4a and 4b. The latching | locking part 7a, 7b called is formed. Each of these locking portions 7a and 7b is configured by bending the leading edge portions of both flange portions 6a and 6b toward the both race portions 5a and 5b in the radial direction. The retainer 3 and the races 4a and 4b are prevented from being separated by engaging the engaging portions 7a and 7b with the outer peripheral edge or the inner peripheral edge of the retainer 3.

  The thrust needle bearing 1 configured as described above is provided, for example, on a stepped portion provided in a housing member or the like constituting a transmission for an automobile, and on an outer peripheral surface of a rotation transmission shaft inserted into the inner diameter side of the housing member. And it arrange | positions in the predetermined position between the axial direction side surfaces of the other members, such as a gearwheel which formed the inclined tooth in the outer peripheral surface. Then, while supporting the thrust load applied to the mating member in accordance with the rotation transmission with another gear, the mating member or the rotation transmitting shaft can be rotated. In this state, the flange portions 6a and 6b provided on the races 4a and 4b are fitted with a part of the inner peripheral surface of the housing member or a part of the outer peripheral surface of the rotation transmission shaft. Therefore, the thrust needle bearing 1 is installed at the predetermined position in a state where the position in the radial direction is restricted.

  Such a method for manufacturing the races 4a and 4b will be described with reference to FIG. FIG. 5 shows a method of manufacturing the race 4a called an outer ring, which is provided with the flange portion 6a on the outer peripheral edge side shown in FIG. The manufacturing method of the race 4b called a so-called inner ring in which the flange 6b is provided on the inner peripheral edge shown in FIG. 4 is basically the same except that the bending position and the bending direction are different.

  In the conventional method, first, a plate-shaped material 8 as shown in FIG. 5A is punched by a press, and a ring-shaped first intermediate material 9 as shown in FIG. To do. The plate-like material 8 has a hardness of Hv200, such as a cold rolled steel plate such as SPCC / SPCE material, a carbon steel plate for mechanical structure such as S ** C material, and a chromium molybdenum steel plate material such as SCM material. In the following (however, Hv100 or more), a hardenable iron-based alloy is used. In an actual case, the plate-like material 8 is a long one drawn from an uncoiler, and the first intermediate material 9 is a plate-like arrangement of the long plate-like material 8. Reduce scrap. The first intermediate material 9 is bent by a press to form a second intermediate material 10 as shown in FIG. The second intermediate material 10 is provided with an annular lace portion 5a and a cylindrical flange portion 6a bent in the axial direction from the outer peripheral edge of the lace portion 5a. The second intermediate material 10 is subjected to a heat treatment necessary for increasing the hardness, such as quenching, nitriding, carbonitriding, etc., and the hardness is increased to Hv 600 to 800, as shown in FIG. Completed as race 4a.

  However, in the conventional manufacturing method as described above, there are many parts that become waste materials, and there is a problem that the yield of materials is poor and the manufacturing cost increases.

  Further, according to the conventional manufacturing method as described above, there is a limit to the plate thickness that can be used as the plate material 8. That is, when the plate is thick, the first intermediate material 9 as shown in FIG. 5B is bent by a press, and the second intermediate material 10 as shown in FIG. In this case, it is difficult to raise the flange portions 6a, 6b, and a bent portion (bending R portion) in which the flange portions 6a, 6b and the race portions 5a, 5b are made continuous during plastic working by pressing. In some cases, damage such as cracks may occur. Of course, it is sufficient to use a simple ring-shaped one (without a cylindrical flange) as the race, but the constituent members can be easily separated in the state before being incorporated into the rotation support portion, and transmissions for automobiles, etc. In many cases, it is difficult to adopt this because it hinders the efficiency of the assembly work of various rotating machinery devices.

JP 2000-266043 A JP 2008-082435 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a manufacturing method of a thrust needle bearing race that is excellent in workability and has a good material yield and can be manufactured at low cost. There is.

The above object of the present invention can be achieved by the following constitution.
(1) a plurality of needles;
A cage for holding the needle in a freely rollable manner;
A thrust needle bearing comprising: an annular race portion that contacts the needle; and at least one race comprising a cylindrical flange portion formed on the entire outer periphery or inner periphery of the race portion. A method of manufacturing a thrust needle bearing race used in
A cutting step of cutting the medium carbon steel wire or round bar to a predetermined length to create a material;
A forging process in which the material is forged to form a flat first intermediate material;
A grinding step of grinding the surface of the first intermediate material to finish a second intermediate material having a predetermined surface roughness;
A shearing process in which the second intermediate material in the previous period is cut into a ring-shaped third intermediate material and a center material by cutting the center portion by pressing;
A burring step of forming a fourth intermediate material having a predetermined shape by raising a flange on the inner peripheral side of the third intermediate material or the outer peripheral side;
A method of manufacturing a thrust needle bearing race, comprising: a heat treatment step of performing carbonitriding, quenching, and tempering hardening treatment on the fourth intermediate material to complete the race.
(2) The medium carbon steel is C 0.1 to 0.5 wt%, Cr 0.5 to 5.0 wt%, Mo 0.0 to 1.5 wt%, Mn 0.1 to 1.5 wt%, SiO An alloy steel having a composition of 0.1 to 1.5% by weight and the balance Fe;
The method for manufacturing a thrust needle bearing race according to (1), wherein the race after the heat treatment has a surface hardness of Hv 650 to 900 and a surface retained austenite of 15 to 50% by volume.
(3) The method for manufacturing a thrust needle bearing race according to (1) or (2), wherein a barrel polishing process is further performed after the heat treatment step.

  According to the method for producing a thrust needle bearing race of the present invention, C 0.1 to 0.5 wt%, Cr 0.5 to 5.0 wt%, Mo 0.0 to 1.5 wt%, Mn 0.1 to 1 .5 wt%, Si 0.1 to 1.5 wt%, and medium carbon steel wire or round bar made of Fe, and cut, forged, ground, sheared, burring, and heat treated to have a predetermined shape The surface hardness is Hv650-900 and the surface retained austenite amount is 15-50% by volume. Therefore, it is superior in workability compared with the conventional method of manufacturing lace using high carbon steel, and is a lean lubrication environment. Even under the above, a race excellent in wear resistance, heat resistance, and peeling resistance can be manufactured at a low cost with a good material yield.

  Furthermore, the cutting material cut by the cutting process is further cut into a second intermediate material by pressing, and the turning process, the surface treatment process, and the grinding process are performed on the other second intermediate material. Since other products smaller than the product are formed, the yield of the material can be further improved as a whole, and the manufacturing cost can be suppressed.

The perspective view which shows one example of embodiment of the manufacturing method of this invention to process order. Sectional drawing which shows an example of the thrust needle bearing conventionally known. Similarly (A) and sectional drawing (B) which show one race in the state seen from the side in which the race surface is provided. The same figure as FIG. 3 about the other race. The perspective view which shows the conventional manufacturing method in order of a process. Sectional drawing which shows two examples of another structure of the thrust needle bearing provided with the race which can apply this invention.

  An example of an embodiment of a method for manufacturing a thrust needle bearing race according to the present invention will be described with reference to FIG. 1 shows a method of manufacturing a so-called inner ring race 4b in which a flange portion 6b is provided on the inner peripheral edge side. However, a so-called outer ring race 4a (see FIGS. 2 and 3) is shown. This can also be carried out in the same manner only by changing the folding position and the folding direction.

  As shown in FIG. 1, the production of the race 4b is as follows: C 0.1 to 0.5 wt%, Cr 0.5 to 5.0 wt%, Mo 0.0 to 1.5 wt%, Mn 0.1 to 1.5 A material 21 obtained by cutting a wire or round bar 20 of medium carbon steel (for example, equivalent to JIS standard symbol SAC1) having a composition of wt%, Si 0.1 to 1.5 wt%, and the balance Fe into a predetermined length. Cutting process (FIGS. 1A and 1B), forging process (FIG. 1C) forging the material 21 to form a flat first intermediate material 22, A grinding process (FIG. 1 (d)) in which the surface of the first intermediate material 22 is ground to finish the second intermediate material 23 having a predetermined surface roughness, and the second intermediate material 23 is centered by pressing. The portion is cut off and separated into a ring-shaped third intermediate material 24 and a cutout material 25 (FIG. 1 (e)). ) A shearing step and a burring step in which the flange portion 26 is raised on the inner peripheral edge side or the outer peripheral edge side of the third intermediate material 24 to form a fourth intermediate material 27 having a predetermined shape (FIG. 1 (f)). The fourth intermediate material 27 is subjected to carbonitriding, quenching, and tempering hardening processes to complete the race 4b (FIG. 1 (g)). A barrel polishing process may be further performed as necessary.

  The opening material 25 can be used as a second intermediate material of a small lace when it is used as a scrap material or can be used as a material for a small lace. Specifically, the cutting material 25 cut by the shearing process is further cut by the shearing process to form another third intermediate material 24 for forming other small products, and other smaller products. (Race) is produced. Thereby, the first half processing (cutting and forging processing) of the small lace manufacturing process can be omitted, the manufacturing cost is suppressed, and the yield of the material is further improved as a whole.

  In addition, as the other third intermediate material 24 for forming other small products, it is also possible to use a cutting material generated in the manufacturing process of the tapered roller bearing, which is often manufactured from medium carbon steel. In this case, the material (medium carbon steel) of the tapered roller bearing and the races 4a and 4b of the thrust needle bearing 1 can be shared, and the manufacturing cost can be further reduced.

  The races 4a and 4b according to the present invention use medium carbon alloy steel having the above composition containing C to 0.5% by weight, and subjected to carbonitriding, quenching, and tempering treatment to obtain a surface hardness of Hv650. 900, the amount of surface retained austenite is 15 to 50% by volume.

  Hereinafter, the action of the alloy steel according to the present invention and the critical significance of the characteristic values will be described.

  Among the components contained in the medium carbon alloy steel, Cr, Mn, and Si are all components that contribute to the improvement of hardenability. In particular, Mn easily generates retained austenite, and Si is a base structure. Strength is increased and Cr imparts wear resistance.

C 0.1 to 0.5% by weight is less than 0.1% by weight, the carburizing time for obtaining a desired hardness (surface hardness Hv 650 to 900) is increased, and solid solution in austenite diffusion length of carbon is increased to, so that a solid solution state of carbon in austenite source of stress concentration is generated becomes uneven, also decreases the life L ₁₀ tired rolling. On the other hand, if it is larger than 0.5% by weight, the amount of dissolved carbon in the austenite becomes excessive, and as a result, the retained austenite after quenching increases and the surface hardness decreases. Moreover, it is because forgeability worsens when carbon content increases.

  The Mn content of 0.1 to 1.5% by weight is 0.1% by weight or more, which improves hardenability and acts as a deoxidizer during dissolution and scouring. However, when it is larger than 1.5% by weight, the retained austenite is increased and the machinability and hot workability of the steel material are lowered.

The content of Si 0.1 to 1.5% by weight is 0.1% by weight or more, which contributes to improvement in hardenability and deoxidation. However, when it is larger than 1.5% by weight, the surface is decarburized during the heat treatment, and ferrite is increased in the core part, so that press formability, cold forgeability and mechanical properties are deteriorated. If the range Si content of 0.1 to 1.5 wt%, and improved crush value, due to the fact that also contribute to the improvement of the life _{L 10} tired rolling.

  Si has a deoxidizing effect, is an element that improves temper softening resistance and is effective in improving heat resistance. Si is an element that stabilizes austenite, and has the effect of delaying the decomposition rate of retained austenite. For this reason, a rolling life may fall that it is less than 0.1 weight%. However, when it is more than 1.5% by weight, the toughness is deteriorated.

  The Cr content of 0.5 to 5.0% by weight is 0.5% by weight or more, and contributes to improvement in hardenability, carburization, wear resistance, and mechanical properties. However, if it is larger than 5.0% by weight, it is due to excessive carburization, increasing the retained austenite, and increasing the amount of granular carbides and making the carburized hardened layer brittle.

  Further, when foreign matter is mixed in the lubricating oil or the like, indentations are generated in the rolling surface layer, and cracks generated at the edge portions of the indentations are often spread to eventually cause fatigue failure. This crack has been found to be closely related to retained austenite. Residual austenite varies depending on the C content of the material, but is usually soft and viscous. Therefore, when this retained austenite is present in the rolling surface layer at a desired ratio, stress concentration at the edge portion of the indentation can be relaxed, and the generation of cracks can be suppressed.

  Further, the retained austenite in the rolling surface layer undergoes martensitic transformation due to the deformation energy applied to the surface when the number of relative passages of the member that passes through the indentation during rolling (for example, the rolling element with respect to the race) exceeds a predetermined number, This has the effect of hardening, and contributes to the improvement of the life of the thrust needle bearing 10 under lubrication mixed with foreign matter.

  The amount of retained austenite on the surface is set to 15 to 50% by volume. If the amount of retained austenite is less than 15% by volume, the stress concentration effect at the occurrence of dust indentation cannot be sufficiently exerted, and the amount of retained austenite is 50% by volume. If the ratio exceeds 50%, the effect of relaxing the stress concentration is saturated. On the contrary, the surface hardness is lowered, the fatigue resistance is lowered, and the life is shortened even under foreign matter-mixed lubrication and clean lubrication.

  For this reason, the surface hardness is set in the range of Hv650 to 900, with the lower limit value being Hv650.

  As described above, according to the method for manufacturing the thrust needle bearing race of the present embodiment, the conventional race using the belt steel obtained by cold rolling high carbon steel (for example, JIS standard symbol SUJ2). Compared with this manufacturing method, a race excellent in workability and excellent in wear resistance, heat resistance, and peeling resistance can be manufactured at low cost even in a dilute lubrication environment.

In order to confirm the effect of the present invention, an example relating to a method for manufacturing a thrust needle bearing race of the present invention and a comparative example to be compared with the example will be described.

  In both the examples and comparative examples, the races used in the test were manufactured by the manufacturing method according to the embodiment of the present invention, except that the round bars of the alloy steels having the compositions shown in Table 1 were cut into raw materials and the heat treatment conditions were excluded.

  In Table 1, types A to F of alloy steel have compositions included in the scope of the present invention, and types G to H of alloy steel are compositions outside the scope of the present invention.

  Table 2 compares and shows the results of rolling fatigue life tests conducted under the following life test conditions using various alloy steels and races of surface properties (surface hardness, surface retained austenite amount). The rolling fatigue life is shown as a ratio to the life of the type H alloy steel of Comparative Example 6 as a reference. The type H of the alloy steel is a high carbon steel equivalent to the JIS standard symbol SUJ2, and is a standard because it is an alloy steel generally used in conventional races.

(Life test conditions)
Life Tester: NSK Thrust Needle Tester Test Bearing: PCD 50mm, Needle φ3mm × 6mm
Basic dynamic load rating C: 24000N
Basic static load rating C ₀ : 55000N
Thrust load: 5000N
Relative rotation speed: 10000rpm
Lubricating oil and oil temperature: ATF, 100 ° C

  As can be seen from Table 2, the rolling fatigue life of the races of Examples 1 to 7 is more than four times that of the race of SUJ2 (Comparative Example 6), which is a conventional material. The fatigue life is long. On the other hand, the alloy steel type G, whose alloy composition component is outside the range of the present invention, had a rolling fatigue life that was almost the same as that of the alloy steel type H. Further, even if the alloy composition components are alloy steel types A to F having a composition within the range of the present invention, if the surface hardness and surface retained austenite are out of the range of the present invention, it is compared with the alloy steel type H. Thus, the rolling fatigue life was almost the same. Thus, the race of the example has a longer rolling fatigue life than any of the races of the comparative examples, thus demonstrating the effectiveness of the present invention.

  Next, each alloy steel having a thickness of 0.6 mm to 3.0 mm and each 1000 samples are manufactured by the manufacturing method according to the embodiment of the present invention, and a crack in the bent portion (bending R portion) in which the flange portion and the race portion are made continuous. Table 3 shows the results of examining the presence or absence of such damage. For the test, a NSK press tester was used to produce a race having an inner diameter of 35 mm × outer diameter of 65 mm and an inner peripheral flange height of 3 mm, and a bent portion (bent R portion) in which the flange portion and the race portion are continuous. The number of samples with damage such as cracks was recorded.

  From Table 3, it can be seen that in the alloy steel type H, which is a conventional material, about 3% of the samples are damaged even when the plate thickness is 0.6 mm, and the number of damaged samples increases as the plate thickness increases. On the other hand, in the types of alloy steels A and F having the composition within the scope of the present invention, even if the plate thickness is 3.0 mm, no damage such as cracks occurs in 1 out of 1000 samples. Sex has been demonstrated.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  Furthermore, the present invention is not limited to the thrust needle bearing having the structure as shown in FIG. 2 described above, but can be implemented with respect to the thrust needle bearings 1a and 1b as shown in FIGS. . The thrust needle bearing 1 shown in FIG. 2 sandwiches the needles 2 and 2 by a pair of races 4a and 4b. On the other hand, the thrust needle bearing 1a shown in FIG. 6 (A) has a race 4a called an outer ring, and the thrust needle bearing 1c shown in FIG. 6 (B) has a race 4b called an inner ring. It is provided only on one side of the needles 2 and 2.

  As described above, according to the method for manufacturing a thrust needle bearing race of the present invention, C 0.1 to 0.5 wt%, Cr 0.5 to 5.0 wt%, Mo 0.0 to 1.5 wt% , Cutting, forging, grinding, shearing, burring from medium carbon steel wire rods or round bars made of Mn 0.1-1.5 wt%, Si 0.1-1.5 wt% and balance Fe , And a heat-treated lace having a predetermined shape, and having a surface hardness of Hv 650 to 900 and a surface retained austenite amount of 15 to 50% by volume, it is easier to process than a conventional method of manufacturing a lace using high carbon steel. Because it is possible to manufacture a race that is excellent in wear resistance, heat resistance, and peeling resistance even in a dilute lubrication environment with good material yield and low cost, an automobile transmission (manual transmission and Self Manufacturing of a race that constitutes a thrust needle bearing that supports a thrust load applied to the rotary support unit by incorporating it into a rotary support unit of various rotary machine devices such as compressors for various refrigerators such as car transmissions) It can be suitably used as a method.

1, 1a, 1b, 1c Thrust needle bearing 2 Needle 3, 3a Cage 4a, 4b Race 5a, 5b Race part 6a, 6b Flange part 7a, 7b Locking part 8 Plate material 9 First intermediate material 10 Second intermediate Material 11 Third intermediate material 20 Wire rod or round bar material 21 Material 22 First intermediate material 23 Second intermediate material 24 Third intermediate material 25 Sealing material 26 Flange portion 27 Fourth intermediate material

Claims (3)

A plurality of needles;
A cage for holding the needle in a freely rollable manner;
A thrust needle bearing comprising: an annular race portion that contacts the needle; and at least one race comprising a cylindrical flange portion formed on the entire outer periphery or inner periphery of the race portion. A method of manufacturing a thrust needle bearing race used in
A cutting step of cutting the medium carbon steel wire or round bar to a predetermined length to create a material;
A forging process in which the material is forged to form a flat first intermediate material;
A grinding step of grinding the surface of the first intermediate material to finish a second intermediate material having a predetermined surface roughness;
A shearing process in which the second intermediate material in the previous period is cut into a ring-shaped third intermediate material and a center material by cutting the center portion by pressing;
A burring step of forming a fourth intermediate material having a predetermined shape by raising a flange on the inner peripheral side of the third intermediate material or the outer peripheral side;
A method of manufacturing a thrust needle bearing race, comprising: a heat treatment step of performing carbonitriding, quenching, and tempering hardening treatment on the fourth intermediate material to complete the race. The medium carbon steel is C0.1-0.5 wt%, Cr0.5-5.0 wt%, Mo0.0-1.5 wt%, Mn0.1-1.5 wt%, Si0.1 An alloy steel having a composition of 1.5% by weight and the balance Fe,
2. The method for manufacturing a thrust needle bearing race according to claim 1, wherein the race after the heat treatment has a surface hardness of Hv650 to 900 and a surface retained austenite of 15 to 50% by volume. 3. The method for manufacturing a thrust needle bearing race according to claim 1, further comprising a barrel polishing treatment after the heat treatment step.

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