Manufacturing method of machine component, manufacturing method of bearing, machine component, bearing, machine, and vehicle

Abstract

To increase a life of a burnishing tool used for burnishing.SOLUTION: A manufacturing method of a machine component includes: grinding step in which grinding is performed to a processed surface, which is a portion provided with a contact surface of an intermediate material made of a metal material, by a general grindstone; removal step in which removal processing for removing foreign objects adhering to the processed surface is performed after the grinding step; and burnishing step in which burnishing is performed on the processed surface after the removal step.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a machine component, a method for manufacturing a bearing, a machine component, a bearing, a machine, and a vehicle. [Background technology]

[0002] Rotating members of various rotating machinery are rotatably supported relative to a part that does not rotate even when in use, such as a housing, by a radial rolling bearing 1 as shown in Fig. 1. Radial rolling bearing 1 comprises an inner ring 3 having an inner ring raceway 2 on its outer circumferential surface, an outer ring 5 having an outer ring raceway 4 on its inner circumferential surface, and a plurality of rolling elements 6 disposed between the inner ring raceway 2 and the outer ring raceway 4 so as to be able to roll freely.

[0003] It is desirable to improve the residual compressive stress of the inner and outer raceways that are in rolling contact with the rolling elements in order to improve the indentation resistance. WO 2021 / 220749 describes a method of performing burnishing to improve the residual compressive stress of the inner and outer raceways. Burnishing is a processing method in which a roller or a ball is pressed against a workpiece surface to cause plastic deformation and work hardening on the surface of the workpiece surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 220749 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] In order to reduce the manufacturing costs of rolling bearings while improving the compressive residual stress in the inner ring raceway and outer ring raceway by performing burnishing, it is desirable to improve the life of the burnishing tool (e.g., rollers, balls, etc.) used in the burnishing process.

[0006] The present disclosure aims to provide a method for manufacturing a machine part that can extend the life of a burnishing tool (e.g., a roller, a ball, etc.) used in burnishing processing, and a machine part manufactured by the method. The present disclosure also aims to provide a method for manufacturing a bearing that can extend the life of the burnishing tool, and a bearing manufactured by the method. [Means for solving the problem]

[0007] The present inventors have conducted extensive research into the causes of the deterioration of the durability of a burnishing tool used in burnishing, and have found that one of the causes is that foreign matter such as abrasive grains produced during mechanical processing performed prior to the burnishing process adheres to the surface of the burnishing tool, causing scratches or other damage to the surface. The present disclosure has been completed based on such findings.

[0008] The mechanical component which is the target of the manufacturing method of the mechanical component according to the first and second aspects of the present disclosure is made of a metallic material and has a contact surface which comes into rolling contact or sliding contact with a mating member.

[0009] The method for manufacturing a mechanical component according to the first aspect of the present disclosure includes: a grinding process for grinding a surface to be processed, which is a portion of an intermediate material made of a metal material on which the contact surface is to be formed, using a general grinding wheel; a removing step of performing a removing process for removing foreign matter adhering to the work surface after the grinding step; a burnishing step of performing a burnishing process on the processed surface after the removing step; Equipped with.

[0010] A method for manufacturing a mechanical component according to a second aspect of the present disclosure includes: a grinding step of grinding a surface to be processed, which is a portion of an intermediate material made of a metal material on which the contact surface is to be formed, with a superabrasive grindstone; a burnishing process for performing a burnishing process on the surface to be processed after the grinding process; Equipped with.

[0011] A third aspect of the present disclosure is a method for manufacturing a mechanical component according to the second aspect of the present disclosure, further comprising a removal step of performing a removal treatment to remove foreign matter adhering to the workpiece surface after the grinding step and before the burnishing step.

[0012] In a fourth aspect of the present disclosure, in the method for manufacturing a mechanical part of the first or third aspect of the present disclosure, the removal process may include a cleaning process of spraying a cleaning liquid onto the processed surface.

[0013] In the manufacturing method for a mechanical part of the fifth aspect of the present disclosure, in the manufacturing method for a mechanical part of the first or third aspect of the present disclosure, the removal process may include a finishing process of applying ultra-finishing processing to the processed surface.

[0014] In addition, the manufacturing method of the mechanical component according to the fourth aspect of the present disclosure and the manufacturing method of the mechanical component according to the fifth aspect of the present disclosure may be combined and carried out. That is, in the removing treatment step, both the cleaning treatment and the finishing treatment may be carried out in any order.

[0015] In the manufacturing method for a mechanical part of a sixth aspect of the present disclosure, in the manufacturing method for a mechanical part of the fifth aspect of the present disclosure, the superfinishing process is performed by pressing a superfinishing stone against the processed surface of the intermediate material rotating around its own central axis while oscillating it.

[0016] In the seventh aspect of the present disclosure, in the method for manufacturing a mechanical component of the first or second aspect of the present disclosure, the processing equipment used for the burnishing process has a configuration in which the position and / or posture of a burnishing tool is controlled.

[0017] In an eighth aspect of the present disclosure, in the method for manufacturing a mechanical part of the seventh aspect of the present disclosure, the processing equipment used for the burnishing process has a monitoring mechanism for monitoring the processing state of the burnishing tool against the workpiece surface.

[0018] The bearing that is the subject of the bearing manufacturing method of the ninth aspect of the present disclosure is A plurality of rolling elements; an outer ring having an outer ring raceway on an inner circumferential surface thereof that is in rolling contact with the plurality of rolling elements; an inner ring having an inner ring raceway on an outer circumferential surface thereof in rolling contact with the plurality of rolling elements; Equipped with.

[0019] In a method for manufacturing a bearing according to a ninth aspect of the present disclosure, the outer ring and / or the inner ring is manufactured by the method for manufacturing a machine component according to any one of the first to eighth aspects of the present disclosure.

[0020] A mechanical part according to a tenth aspect of the present disclosure includes: Constructed of a metal material, A contact surface is provided that is in rolling contact or sliding contact with a mating member, The contact surface is a burnished surface and is constituted by a plateau surface that is free of periodic cutting marks.

[0021] A bearing according to an eleventh aspect of the present disclosure includes: an outer ring made of a metallic material having an outer ring raceway on an inner peripheral surface; an inner ring made of a metallic material having an inner ring raceway on an outer circumferential surface; a plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway for free rolling; Equipped with.

[0022] In particular, in the bearing according to the eleventh aspect of the present disclosure, The outer ring raceway and / or the inner ring raceway are formed of a burnished plateau surface that is free of periodic cutting marks.

[0023] A machine according to a twelfth aspect of the present disclosure includes the bearing according to the eleventh aspect.

[0024] A vehicle according to a thirteenth aspect of the present disclosure includes the bearing according to the eleventh aspect. Effect of the Invention

[0025] According to the method for manufacturing a machine component and the method for manufacturing a bearing of one aspect of the present disclosure, it is possible to extend the life of a burnishing tool used in burnishing processing. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a partially cutaway perspective view showing a radial rolling bearing according to one embodiment. [Diagram 2] FIG. 2 is a flow chart showing a method for manufacturing a machine component according to an embodiment. [Diagram 3] FIG. 3 is a partially enlarged cross-sectional view showing a state in which a grinding process is performed on an inner ring raceway of an inner ring that constitutes a radial rolling bearing. [Figure 4] Part (A) of Figure 4 is a partially enlarged cross-sectional view showing how the inner ring raceway is subjected to a removal treatment by superfinishing, and part (B) of Figure 4 is a partially enlarged cross-sectional view showing how the inner ring raceway is subjected to a removal treatment by cleaning. [Diagram 5] FIG. 5 is a partially enlarged cross-sectional view showing how the inner ring raceway is burnished. [Figure 6] Part (A) of FIG. 6 is a partially enlarged cross-sectional view showing a schematic view of an inner ring raceway of an inner ring constituting a radial rolling bearing, and part (B) of FIG. 6 is a partially enlarged cross-sectional view showing a schematic view of an inner ring raceway of an inner ring of a comparative example. [Figure 7] FIG. 7 is a graph diagram showing a schematic relationship between the depth from the inner ring raceway and the residual compressive stress. [Figure 8] FIG. 8 is a graph diagram showing a schematic relationship between the burnishing length and the damaged area of ​​the burnishing tool (ball). [Figure 9] FIG. 9 is a schematic diagram showing the state of damage on the surface of the burnishing tool in comparison. [Figure 10] FIG. 10 is a diagram showing an example of an apparatus including a mechanical component to which the manufacturing method for the mechanical component can be applied, where part (A) of FIG. 10 is a partially cutaway perspective view showing a radial cylindrical roller bearing, part (B) of FIG. 10 is a cross-sectional view showing a radial sliding bearing, and part (C) of FIG. 10 is a cross-sectional view showing a cylinder device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] An embodiment of the present disclosure will be described with reference to FIGS.

[0028] This embodiment is an example in which a manufacturing method for a machine component according to an aspect of the present invention is applied to a manufacturing method for an inner ring 3 constituting a radial rolling bearing 1 which is a bearing.

[0029] In one embodiment, as shown in FIG. 2, the manufacturing method for a mechanical component includes a machining process (S101) in which a metallic material is machined to obtain a preliminary intermediate material, a heat treatment process (S102) in which the preliminary intermediate material is heat treated to obtain an intermediate material, a grinding process (S103) in which a grinding surface, which is a portion of the metallic intermediate material on which a contact surface is formed, is ground using a general grinding wheel, a removal process (S104) in which, after the grinding process, a removal process is performed to remove foreign matter adhering to the processed surface, and a burnishing process (S105) in which, after the removal process, a burnishing process is performed on the processed surface.

[0030] <Structure of radial rolling bearings> As shown in FIG. 1, the radial rolling bearing 1 includes an inner ring 3, an outer ring 5, and a plurality of rolling elements 6.

[0031] In this embodiment, a ball is used as each of the plurality of rolling elements 6. That is, the radial rolling bearing 1 constitutes a radial ball bearing. In one example, the radial rolling bearing 1 constitutes a single-row deep groove radial ball bearing.

[0032] The inner ring 3 has an inner ring raceway 2 on its outer circumferential surface.

[0033] The inner ring raceway 2 has a generatrix shape of a circular arc. The generatrix shape of the inner ring raceway 2 has a radius of curvature that is slightly larger than the diameter of the rolling elements 6 which are balls, that is, half the ball diameter.

[0034] The inner ring 3 is made of a metallic material such as high carbon chromium steel such as SUJ2 to SUJ4, high carbon chromium steel that has been subjected to carburizing or carbonitriding treatment, carbon steel such as S53C, or hard metal such as carburizing steel such as SCr420 or SCM420.

[0035] The outer ring 5 has an outer ring raceway 4 on its inner circumferential surface.

[0036] The outer ring raceway 4 has a generatrix shape of a circular arc. The generatrix shape of the outer ring raceway 4 has a radius of curvature that is slightly larger than half the ball diameter of the rolling elements 6.

[0037] The outer ring 5 is made of a metallic material such as high carbon chromium steel such as SUJ2-4, high carbon chromium steel that has been carburized or carbonitrided, carbon steel such as S53C, or hard metal such as carburized steel such as SCr420 or SCM420. The outer ring 5 can be made of the same metallic material as the inner ring 3, or can be made of a metallic material different from that of the inner ring 3.

[0038] The plurality of rolling elements 6 are held by a cage 7 so as to be freely rollable at a plurality of locations equally spaced apart in the circumferential direction between the inner ring raceway 2 and the outer ring raceway 4 .

[0039] Each of the rolling elements 6 is made of a hard metal material, such as bearing steel or hardened carbon steel, or ceramic.

[0040] <Manufacturing method of the inner ring> In one embodiment, the inner ring 3 is manufactured by the manufacturing method of the machine component according to one aspect of the present disclosure. That is, the inner ring raceway 2 that is in rolling contact with the multiple rolling elements 6 constitutes a contact surface.

[0041] The manufacturing method of the inner ring 3 includes a grinding process in which a grinding process is performed using an ordinary grinding wheel on a workpiece surface 8, which is the portion of an intermediate material 9 made of a metallic material on which the inner ring raceway 2 is formed, a removal process in which, after the grinding process, a removal treatment is performed to remove foreign matter adhering to the workpiece surface 8, and a burnishing process in which, after the removal process, a burnishing process is performed on the workpiece surface 8.

[0042] The intermediate material 9 has a removal allowance at a radially outer portion including the processed surface 8, which is removed in the grinding step and the removing step.

[0043] To obtain the intermediate material 9, first, a metal material is forged to form the rough shape of the inner ring 3, and then the axially middle portion of the outer circumferential surface is machined to form the machined surface 8, thereby obtaining a preliminary intermediate material.

[0044] Next, the preliminary intermediate material is subjected to a heat treatment to obtain the intermediate material 9.

[0045] The heat treatment includes quenching and tempering, both of which are performed by heating the preliminary intermediate material to a target temperature, holding the temperature for a predetermined period of time, and then cooling the material.

[0046] The preliminary intermediate material can be heated in the quenching and tempering processes using a heating furnace. The heating furnace is not particularly limited, but an electric furnace can be used, and preferably a high-frequency induction furnace can be used.

[0047] The heating temperature and heating time of the preliminary intermediate material in the quenching treatment and tempering treatment, respectively, are appropriately set depending on the metal material constituting the inner ring 3.

[0048] <Grinding process> In the grinding step, a surface 8 to be processed of the intermediate material 9 is subjected to grinding by a grinding wheel 10 which is a general grinding wheel.

[0049] The grinding wheel 10 is a rotating grinding wheel having a generatrix shape in which the concaves and convexes are inverted relative to the generatrix shape of the inner ring raceway 2 to be formed, and is a general grinding wheel made by bonding general abrasive grains such as alumina (Al2O3)-based or silicon carbide (SiC)-based grains with a binder such as a vitrified bond or a resinoid bond.

[0050] The grit size of the grindstone 10, which indicates the grain size of the abrasive grains, is not limited to this, but can be from #50 to #200.

[0051] The grinding process is performed by rotating the intermediate material 9 around the central axis of the intermediate material 9 while pressing the outer surface of a grinding wheel 10, which rotates around a central axis arranged parallel to the central axis of the intermediate material 9, against the processed surface 8 of the intermediate material 9.

[0052] In the grinding step, the surface 8 to be processed is ground to remove the removal amount, leaving only the amount to be removed in the subsequent removing step.

[0053] Of the removal amount, the thickness of the portion removed in the removal step is not particularly limited, but can be, for example, 10 μm or less.

[0054] After the grinding process, minute irregularities exist on the processed surface 8. The minute irregularities are irregular at least in the axial direction.

[0055] The arithmetic mean roughness Ra of the work surface 8 after grinding is not limited to this, but can be, for example, 0.3 μm or less. The lower limit of the arithmetic mean roughness Ra of the work surface 8 after grinding is not particularly limited, but is 0.1 μm or more, taking into consideration that a general grinding wheel is used as the grinding wheel 10.

[0056] <Removal process> In the removing step, a removing process is carried out to remove foreign matter such as abrasive grains adhering to the processing surface 8.

[0057] In one example, as shown in part (A) of Fig. 4, a superfinishing process is performed on the workpiece surface 8 as a removal process for removing foreign matter including residual grindstone attached to the workpiece surface 8. Specifically, a superfinishing grindstone 11 is pressed against the workpiece surface 8 of an intermediate material 9 rotating about its own central axis while being oscillated (finely vibrated). More specifically, for example, the superfinishing grindstone 11 is pressed against the workpiece surface 8 of the intermediate material 9 rotating about its own central axis while being oscillated and oscillated about the center of curvature of the inner ring raceway 2. In this way, foreign matter attached to the workpiece surface 8 during grinding using a general grindstone is removed by polishing it off.

[0058] The abrasive grains used in the superfinishing grindstone 11 are not particularly limited, and alumina-based, silicon carbide-based, cubic boron nitride (CBN)-based, or diamond (SD)-based abrasive grains can be used. Preferably, cubic boron nitride-based or diamond-based abrasive grains are used.

[0059] The grit size of the superfinishing whetstone 11, which indicates the grain size of the abrasive grains, is not limited to this, but can be from #800 to #10,000, and preferably from #1,000 to #3,000.

[0060] The binder used for the superfinishing wheel 11 is not limited to this, but a vitrified bond or a resin bond can be used.

[0061] The arithmetic mean roughness Ra of the processed surface 8 after the removal process is not limited to this, but can be, for example, 0.03 μm or less.

[0062] Alternatively, as the removal process, a cleaning process can be performed in which a cleaning liquid is sprayed onto the work surface 8, as shown in part (B) of Fig. 4. Specifically, when performing the cleaning process, high-pressure industrial water 21 is sprayed from a nozzle 20 onto the work surface 8 at high pressure while rotating the intermediate material 9, thereby washing away foreign matter such as abrasive grains that have adhered to the work surface 8 by the grinding process.

[0063] Instead of the industrial water 21, a weak alkaline cleaning agent or a fluorine-based solvent may be used as the cleaning liquid.

[0064] After the cleaning process, the intermediate material 9 is dried, if necessary, by hot air drying or heat drying to remove moisture adhering to the surface.

[0065] As the removal treatment, both the cleaning treatment and the superfinishing treatment may be carried out in any order.

[0066] In any case, even after the removal process, fine irregularities that are irregular at least in the axial direction are present on the processed surface 8. The intermediate material 9 from which the foreign matter adhering to the processed surface 8 has been removed by the removal process is sent to the next burnishing process.

[0067] <Burnishing process> In the burnishing process, a burnishing tool (e.g., a roller, ball, etc.) is pressed against the work surface 8 of the intermediate material 9 to perform burnishing, which causes plastic deformation and work hardening on the work surface 8 (surface). The surface of the burnishing tool (13) and the work surface 8 move relative to each other while in contact with each other, and the work surface 8 is burnished / burnish-polished.

[0068] In one example, a ball 13 held at the tip of a mandrel 12 is pressed against a work surface 8 of an intermediate material 9 rotating around its own central axis, while being moved along the work surface 8 as shown by the arrow α in Fig. 5. This smooths out minute protrusions present on the work surface 8. As a result, the work surface 8 becomes a plateau surface in which the corners of the protrusions are crushed by minute plastic deformation, and the inner ring raceway 2, which is a burnished surface, is obtained.

[0069] The ball 13 can be pressed against the work surface 8 in a direction inclined at a predetermined angle θ with respect to a direction perpendicular to the work surface 8. For example, the angle θ can be greater than 0 degrees and equal to or less than 30 degrees. By inclining the ball 13 at the predetermined angle θ, it is possible to perform burnishing on the work surface 8 while preventing interference between the mandrel 12 and the work surface 8. However, the ball 13 can also be pressed against the work surface 8 in a direction perpendicular to the work surface 8, i.e., the angle θ can be set to 0 degrees.

[0070] The balls 13 are made of a material harder than the metallic material that constitutes the inner ring 3. Specifically, the balls 13 can be made of, for example, a cemented carbide alloy, ceramics, or the like.

[0071] The inner ring raceway 2 of the inner ring 3 obtained through the grinding process using a general grinding wheel, the removing process, and the burnishing process is composed of a plateau surface that does not have periodic cutting marks, as shown in part (A) of Fig. 6. In other words, the inner ring raceway 2 is composed of a plateau surface in which recesses are irregularly arranged at least in the axial direction.

[0072] Burnishing is generally performed on a surface that has been subjected to cutting such as turning. A spiral cutting kerf is formed on the surface that has been subjected to turning. Therefore, after turning, the burnished processed surface 14 is composed of a plateau surface on which periodic cutting kerfs are formed, as shown in part (B) of FIG. 6.

[0073] The burnished surface does not only refer to a surface immediately after the burnishing process, but also includes a surface that has been lightly polished after the burnishing process, or a surface that has been lightly ground and then superfinished. After the burnishing process, the surface is lightly polished or ground to a degree that does not remove the compressive residual stress while retaining the characteristics of a plateau surface that does not have periodic cutting marks, and then superfinished as necessary, thereby making it easier to adjust the surface properties to the desired properties while imparting compressive residual stress. In particular, when the present disclosure is applied to the raceway surface of a bearing, it is possible to achieve a high level of both load resistance and surface roughness.

[0074] The arithmetic mean roughness Ra of the inner ring raceway 2 of the inner ring 3 obtained by the above-mentioned manufacturing method is, but is not limited to, 0.2 μm or less. The Rockwell hardness HRC of the inner ring raceway 2 is, but is not limited to, 55 or more and 64 or less.

[0075] Further, the compressive residual stress at a position of a depth of 300 μm from the inner ring raceway 2 in the inner ring 3 is, but is not limited to, 400 MPa or more.

[0076] Fig. 7 is a graph diagram showing a schematic relationship between the depth from the inner ring raceway 2 and the residual compressive stress. In the manufacturing method of the inner ring 3 of this embodiment, the inner ring 3 is manufactured by burnishing the machined surface 8, which is the portion of the intermediate material 9 made of a metallic material where the inner ring raceway 2 is to be formed. For this reason, as shown by the solid line α in Fig. 7, the residual compressive stress in the portion of the inner ring 3 that is present radially inward of the inner ring raceway 2 can be improved compared to an unmachined product (dotted line β in Fig. 7) that has not been subjected to burnishing.

[0077] In particular, the inner ring 3 manufactured by burnishing as in this embodiment has a significant effect on improving the indentation resistance of the inner ring raceway 2, and the residual compressive stress at a depth of 300 μm from the inner ring raceway 2 is better secured than that of the unprocessed product and that in which shot peening is performed instead of burnishing (dashed line γ in FIG. 7), specifically, the residual compressive stress at a depth of 300 μm from the inner ring raceway 2 can be made 400 MPa or more. Therefore, the indentation resistance of the inner ring raceway 2 can be well secured.

[0078] Even when shot peening is performed, the residual compressive stress of the part of the inner ring that is present inside the inner raceway can be improved compared to an unprocessed product. However, when the depth from the inner raceway is about 150 μm or more, the residual compressive stress rises sharply. In addition, shot peening is a process in which a projectile called a shot is collided with the workpiece at high speed to plastically deform the surface of the workpiece into a fine uneven shape, which deteriorates the surface roughness.

[0079] In contrast, in the manufacturing method of the inner ring 3 of this embodiment, in order to improve the residual compressive stress, a burnishing process is performed in which a ball 13 is pressed against the processed surface 8 to smooth out minute protrusions present on the processed surface 8. As a result, the surface roughness of the inner ring raceway 2 can be improved, specifically, the arithmetic mean roughness can be made 0.2 μm or less, compared to the case where shot peening is performed.

[0080] In the manufacturing method of the inner ring 3 of this embodiment, a grinding step is performed before the burnishing step, in which a grinding process is performed on a workpiece surface 8 of an intermediate material 9 made of a metallic material using a grinding wheel 10, which is a general grinding wheel, and a removal step is performed after the grinding step, in which a superfinishing process is performed on the workpiece surface 8 to polish off and remove foreign matter such as abrasive grains that have adhered to the workpiece surface 8 during the grinding process using the general grinding wheel. As a result, when a burnishing process is performed in which a ball 13 is pressed against the workpiece surface 8 in the subsequent burnishing step, damage such as scratches caused by foreign matter can be prevented for a long period of time from occurring on the surface of the ball (burnishing tool) 13.

[0081] 8 is a graph diagram showing a schematic relationship between the length (processing distance) of burnishing performed using a ball (burnishing tool) 13 and the damage area of ​​the ball 13. The damage area of ​​the ball 13 can be obtained by subjecting an image of the surface of the ball 13 after burnishing, captured by a camera, to image processing and determining the area of ​​damage present per unit area.

[0082] As shown by dashed line a in Figure 8, when burnishing is performed after a removal step using superfinishing following grinding with a general grindstone, the progression of damage to ball 13 can be slowed compared to when burnishing is performed without a removal step following grinding with a general grindstone (solid line b in Figure 8). As a result, the life of ball 13 used in burnishing can be extended, and the manufacturing cost of radial rolling bearing 1 can be reduced.

[0083] In this embodiment, in the process prior to the burnishing process, grinding with a grindstone 10, which is a general grindstone, and a removal process for removing foreign matter such as abrasive grains that have adhered to the workpiece surface 8 as a result of the grinding are carried out in that order. However, instead of the grinding process with a general grindstone and the removal process by superfinishing, a grinding process in which grinding with a superabrasive grindstone is carried out on the workpiece surface 8 (dotted line c in FIG. 8) can be carried out, or a removal process by superfinishing can be carried out after the grinding process with a superabrasive grindstone (solid line d in FIG. 8). In either case, the progression of damage to the ball 13 can be made slower than when burnishing is carried out without carrying out the removal process after grinding with a general grindstone.

[0084] FIG. 9 is a schematic diagram showing the state of damage on the surface of the burnishing tool in comparison. In each example, the state of the surface of the burnishing tool is shown for each length (processing distance) of the burnishing process. In FIG. 9, in the comparative example, an example is shown in which the burnishing process is performed without performing a removal process after grinding with a general grindstone. In Example 1, an example is shown in which a grinding process is performed on the processed surface with a superabrasive grindstone as a pre-process of the burnishing process. In Example 2, an example is shown in which a removal process is performed by superfinishing after grinding with a superabrasive grindstone as a pre-process of the burnishing process. In Example 1 and Example 2, the degree of damage at a predetermined stage (processing distance) is significantly lower than in the comparative example. In Example 1 and Example 2, a tool life of 10 times or more can be expected compared to the comparative example.

[0085] A superabrasive grinding wheel is made by bonding cubic boron nitride or diamond abrasive grains with a bonding agent such as a vitrified bond or a resinoid bond.

[0086] The grit size of the abrasive grains is not limited to this, but may be from #800 to #100,000, and preferably from #1,000 to #3,000.

[0087] Grinding with a superabrasive grinding wheel can basically be performed in the same manner as grinding with a general grinding wheel 10 as shown in Fig. 3. That is, grinding can be performed by rotating an intermediate material 9 around the central axis of the intermediate material 9, while pressing the outer circumferential surface of a superabrasive grinding wheel rotating around a central axis arranged parallel to the central axis of the intermediate material 9 against the processed surface 8 of the intermediate material 9.

[0088] The grinding process using the superabrasive grindstone can reduce the amount of abrasive grains falling off the grindstone compared to the grinding process using a general grindstone. Therefore, even if a removal process is not performed after the grinding process, damage to the surface of the ball 13 can be prevented for a long period of time in the burnishing process. Compared to general grindstones, the superabrasive grindstone has a higher sand grain retention capacity. In the vitrified bond, a glassy bond is used, and the interface between the sand grains and the bond is chemically bonded. In the resinoid bond, a resin bond such as a phenolic resin is used. The resinoid bond has elasticity based on the resin. In addition, after the grinding process in which the grinding process is performed using the superabrasive grindstone, a removal process can be performed in which a removal process is performed to remove foreign matter attached to the processed surface.

[0089] In one example, the processing equipment used for the burnishing process can have a configuration in which the position and / or the attitude of the burnishing tool is controlled. For example, this control can be based on numerical control and / or hydraulic control. The amount of pressure of the burnishing tool against the target surface (surface to be processed) is controlled with high precision. In addition, the pressure of the burnishing tool against the target surface (surface to be processed) is stably maintained. Highly precise and stable control of the position and / or attitude of the burnishing tool against the target surface (surface to be processed) is advantageous for improving the surface accuracy of the surface to be processed and suppressing damage to the burnishing tool surface.

[0090] In one example, the processing equipment used for burnishing can have a monitoring mechanism for monitoring the processing state of the burnishing tool relative to the workpiece surface. For example, the monitoring mechanism can have a pressure sensor and / or a strain sensor, and monitor output values ​​from the sensor in three axial directions (for example, three orthogonal axial directions (X direction, Y direction, Z direction)). The amount of pressure of the burnishing tool against the target surface (workpiece surface) is controlled with high precision. In addition, the pressure of the burnishing tool against the target surface (workpiece surface) is stably maintained. Furthermore, monitoring the processing state of the burnishing tool relative to the workpiece surface in three dimensions is advantageous for improving the surface accuracy of the workpiece surface and suppressing damage to the burnishing tool surface.

[0091] In this embodiment, the burnishing process uses a spherical ball (burnishing ball) 13, but other burnishing tools, such as a roller (burnishing roller), can be used in the burnishing process. The shape of the roller can be various depending on the shape of the surface to be processed.

[0092] Additionally, the machine part after the burnishing process may be further processed, such as grinding, heat treatment, etc., if necessary.

[0093] In this embodiment, an example has been described in which the manufacturing method for a mechanical component according to the first aspect of the present disclosure is applied to the inner ring 3 of a radial rolling bearing 1, which is a single-row deep groove radial ball bearing, but the present invention is not limited to this and can be applied to various mechanical components that have a contact surface that is in rolling contact or sliding contact with a mating member.

[0094] For example, instead of the inner ring 3 of the radial rolling bearing 1, or in addition to the inner ring 3, the outer ring 5 can also be manufactured by the manufacturing method for a machine component of the present disclosure.

[0095] The manufacturing method of the machine component of the present disclosure can also be applied to the inner ring 3a and / or outer ring 5a of a radial rolling bearing 1a, which is a radial cylindrical roller bearing, as shown in part (A) of Fig. 10. The manufacturing method of the machine component of the present disclosure can also be applied to the inner ring and / or outer ring of a radial rolling bearing such as a radial angular ball bearing or a radial tapered roller bearing. Furthermore, the manufacturing method of the machine component of the present disclosure is not limited to a single-row radial rolling bearing, but can also be applied to a double-row radial rolling bearing.

[0096] The manufacturing method of the machine component of the present disclosure is not limited to radial rolling bearings, but can also be applied to races of thrust rolling bearings. In this case, the raceway surface of the race that comes into rolling contact with the rolling elements corresponds to the contact surface.

[0097] The manufacturing method for a mechanical component according to the present disclosure can also be applied to a sliding bearing 15 as shown in part (B) of Fig. 10. In this case, the inner circumferential surface and / or the outer circumferential surface of the sliding bearing 15 that comes into sliding contact with a mating member corresponds to the contact surface.

[0098] The manufacturing method of the machine component of the present disclosure can also be applied to a piston rod 17 constituting a piston cylinder device 16 as shown in part (C) of Fig. 10. In this case, the outer peripheral surface of the piston rod 17 that comes into sliding contact with the inner peripheral surface of a rod cover 19 attached to the opening of a cylinder tube 18 corresponds to the contact surface.

[0099] The bearing of the present disclosure can be applied to the various bearings described above. For example, the bearing includes a bearing element as the mechanical part described above. For example, the bearing element can be applied to the outer ring or inner ring of a radial rolling bearing, the outer ring or inner ring of a radial cylindrical roller bearing using cylindrical rollers (including needles), and the outer ring or inner ring of a radial tapered roller bearing using tapered rollers.

[0100] The machine of the present disclosure may include the above-mentioned machine part or bearing. The machine part or bearing is applicable to a rotation support part of a machine having a rotating part, various manufacturing devices, for example, screw devices such as ball screw devices, and linear motion devices such as actuators (combinations of linear guide bearings and ball screws, XY tables, etc.). The machine part or bearing is also applicable to steering devices such as wipers, power windows, electric doors, electric seats, steering columns (for example, electric tilt-telescopic steering columns), universal joints, intermediate gears, rack and pinions, electric power steering devices, and worm reduction gears. Furthermore, the machine part or bearing is also applicable to various vehicles such as automobiles, motorcycles, and trains. The bearing of this configuration can be suitably applied to any part that rotates relative to one another, which can lead to improved product quality and reduced costs. [Explanation of symbols]

[0101] 1, 1a Radial rolling bearing 2 Inner raceway 3, 3a Inner ring 4 Outer raceway 5, 5a Outer ring 6 Rolling elements 7 Cage 8 Processed surface 9 Intermediate materials 10. Grindstone 11 Super Finishing Stone 12 Mandrel 13 Ball (burnishing tool) 14 Machining surface 15 Plain bearings 16 Piston cylinder device 17 Piston rod 18 Cylinder tube 19 Rod cover 20 Nozzles 21 Industrial water

Claims

1. A mechanical part made of a metallic material, having a contact surface that makes rolling or sliding contact with a mating member. A method for manufacturing an article, comprising: a grinding process for grinding a surface to be processed, which is a portion of an intermediate material made of a metal material on which the contact surface is to be formed, using a general grinding wheel; a removing step of performing a removing process for removing foreign matter adhering to the work surface after the grinding step; a burnishing step of performing a burnishing process on the processed surface after the removing step; A method for manufacturing a machine component, comprising:

2. A method for manufacturing a metal mechanical part having a contact surface that is in rolling contact or sliding contact with a mating member, comprising the steps of: a grinding process for grinding a surface to be processed, which is a portion of an intermediate material made of a metal material on which the contact surface is to be formed, with a superabrasive grindstone; a burnishing process for performing a burnishing process on the surface to be processed after the grinding process; A method for manufacturing a machine component, comprising:

3. The method for manufacturing a machine component according to claim 2 , further comprising a removing step of performing a removing treatment for removing foreign matter adhering to the processed surface after the grinding step and before the burnishing step.

4. The method for manufacturing a machine component according to claim 1 or 3, wherein the removing process includes a cleaning process in which a cleaning liquid is sprayed onto the processed surface.

5. The method for manufacturing a machine component according to claim 1 or 3, wherein the removing process includes a finishing process of performing a superfinishing process on the processed surface.

6. 6. The method for manufacturing a machine component according to claim 5, wherein the superfinishing is performed by pressing a superfinishing stone against the surface to be processed of the intermediate material rotating about its own central axis while oscillating the superfinishing stone.

7. The method for manufacturing a machine component according to claim 1 or 2, wherein a processing facility used for the burnishing process has a configuration in which a position and / or a posture of a burnishing tool is controlled.

8. The method for manufacturing a machine component according to claim 7 , wherein the processing equipment used for the burnishing process has a monitoring mechanism for monitoring a processing state of the burnishing tool with respect to the surface to be processed.

9. A plurality of rolling elements; an outer ring having an outer ring raceway on an inner circumferential surface thereof that is in rolling contact with the plurality of rolling elements; an inner ring having an inner ring raceway on an outer circumferential surface thereof in rolling contact with the plurality of rolling elements; A manufacturing method of a bearing comprising: The outer ring and / or the inner ring are manufactured by the manufacturing method of the machine component according to claim 1 or 2. A method for manufacturing a bearing comprising the steps of:

10. Constructed of a metal material, A contact surface is provided that is in rolling contact or sliding contact with a mating member, The contact surface is a burnished surface and is a plateau surface that does not have periodic cutting marks. A mechanical part that consists of:

11. an outer ring made of a metallic material having an outer ring raceway on an inner peripheral surface; an inner ring made of a metallic material having an inner ring raceway on an outer circumferential surface; a plurality of rolling elements disposed between the outer ring raceway and the inner ring raceway for free rolling; Equipped with A bearing, wherein the outer ring raceway and / or the inner ring raceway is a burnished surface and is configured as a plateau surface that is free of periodic cutting marks.

12. A machine comprising a bearing according to claim 11.

13. A vehicle comprising the bearing according to claim 11.

Images