JP2016153666A - Process of manufacture of bearing ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process of manufacture of a bearing ring of which manufacturing step is more shortened.SOLUTION: This invention comprises the steps of preparing a steel material 2 and a formation block press 3 for attaining a bearing ring 11 from the steel material 2; mounting the steel material 2 on the formation block 3, after the steel material 2 is heated at the formation block 3 to a temperature equal to or more than a transformation point A; punching out a part of the steel material 2 into a ring-shape; then hardening and processing the ring-shape steel material 2 at the formation block 3 to attain the bearing ring 11. At the stage for attaining the bearing ring 11, both heating and punching-out are carried out under a state in which a tension force is added in at least one direction along the surface of the steel material 2 in respect to the steel material 2.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method of manufacturing a race. In particular, the present invention relates to a method for manufacturing a bearing ring with a shorter manufacturing process.

  Conventionally, a bearing ring of a thrust needle bearing is manufactured by the following process. First, a coil material obtained by winding a rolled thin plate-shaped steel material into a coil shape is prepared. Next, a punching process and a forming process are sequentially performed on the thin plate steel material unwound from the coil material. Thereby, the ring-shaped molded object which has the approximate shape of a raceway ring is obtained. Next, a setup process before heat treatment is performed. Then, a heat treatment such as a carburizing process is performed on the ring-shaped molded body. Thereafter, the molded body is cooled by applying a blast, and the molded body is quenched. Finally, by applying a press temper (tempering treatment) to the molded body after quenching, the shape of the molded body is adjusted. Through the processes as described above, the bearing ring of the thrust needle bearing is manufactured.

  Moreover, the die quench method is known as a steel material forming technique. This die quench method is a technique in which a heated steel material is press-molded and simultaneously quenched with a die for quenching treatment (for example, Patent Document 1).

JP 2008-296262 A

  As described above, the manufacturing process of the conventional thrust needle bearing raceway includes a number of processes such as punching, forming, heat treatment, quenching, and tempering. Further, since the raceway of the thrust needle bearing is thin, it takes time and effort in the setup process before heat treatment. Thus, conventionally, there is a problem that the manufacturing cost of the raceway is increased due to the multi-step manufacturing process. Therefore, it is required to reduce the manufacturing cost by further shortening the manufacturing process of the raceway and to provide a less expensive raceway.

  This invention is made | formed in view of the said subject, The objective is to provide the manufacturing method of the bearing ring whose manufacturing process was shortened more. Another object of the present invention is to provide a less expensive bearing ring with reduced manufacturing costs.

Method of manufacturing a bearing ring according to the present invention includes the steps of: preparing a forming table for obtaining the steel and the bearing ring of steel, the step of installing a steel material forming table, the steel of A ₁ transformation point or above of the molding platform And a step of punching a part of the steel material into a ring shape after heating to a temperature, and thereafter obtaining a ring by quenching the ring-shaped steel material on a forming table. In the step of obtaining the raceway, heating and punching are performed in a state where tension is applied to the steel material in at least one direction along the surface of the steel material.

  According to the method of manufacturing a bearing ring according to the present invention, the manufacturing process of the bearing ring can be further shortened. Moreover, according to the bearing ring according to the present invention, it is possible to provide a less expensive bearing ring with a reduced manufacturing cost.

It is a schematic sectional drawing which shows the structure of the thrust needle roller bearing which concerns on Embodiment 1 of this invention. It is a flowchart which shows roughly the manufacturing method of the bearing ring which concerns on Embodiment 1 of this invention. (A) Time-dependent change in current supplied to the steel material, (B) Time-dependent change in temperature of the steel material, (C) Stroke of the press machine, (D) It is a figure which shows operation | movement of a hydraulic chuck | zipper and (E) operation | movement of a 1st and 2nd clamp part. It is a schematic perspective view which shows the coil material used for the manufacturing method of the bearing ring which concerns on Embodiment 1 of this invention. In the manufacturing method of a bearing ring concerning an embodiment of the invention, it is a schematic sectional view showing the state where steel materials were installed in the press. In the manufacturing method of the bearing ring concerning an embodiment of the invention, it is a schematic sectional view showing the state where current is supplied to steel materials from an energization terminal. In the manufacturing method of a bearing ring concerning an embodiment of the invention, it is a schematic sectional view showing the state where steel materials are punched out by a press. In the manufacturing method of the bearing ring concerning an embodiment of the invention, it is a schematic sectional view showing the state where the steel material punched in the shape of a ring is formed. In the manufacturing method of the bearing ring concerning an embodiment of the invention, it is a schematic sectional view showing the state where the steel material punched in the shape of a ring is quenched. It is a schematic plan view which shows the water cooling circuit provided in the press machine used for the manufacturing method of the bearing ring which concerns on embodiment of this invention. It is the schematic for demonstrating the method to apply tension | tensile_strength with respect to steel materials using the supply part of steel materials. It is the schematic for demonstrating the method to apply tension | tensile_strength with respect to steel materials using the correction part of steel materials. It is the schematic for demonstrating the heating method using electric heating. It is the schematic for demonstrating the heating method using induction heating. It is the schematic for demonstrating the heating method using contact heat transfer. It is a schematic sectional drawing for demonstrating the modification of the manufacturing method of the bearing ring which concerns on embodiment of this invention. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is the schematic for demonstrating the manufacturing method of the bearing ring in a comparative example. It is a schematic sectional drawing which shows the manufacturing apparatus of the bearing ring used for manufacture of the bearing ring which concerns on an Example. It is a photograph of the bearing ring which concerns on an Example. It is a photograph of the steel structure in the bearing ring which concerns on an Example.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  First, the structure of the thrust needle roller bearing 1 which concerns on one embodiment of this invention is demonstrated. FIG. 1 shows a cross-sectional structure along the axial direction of the thrust needle roller bearing 1. With reference to FIG. 1, the thrust needle roller bearing 1 mainly includes a pair of race rings 11, a plurality of needle rollers 12, and a cage 13.

  The race 11 is made of steel having a carbon concentration of 0.4% by mass or more, for example, and has a disk shape. The raceway ring 11 has a raceway rolling surface 11A on one main surface with which the needle roller 12 comes into contact. The pair of race rings 11 are arranged such that the raceway rolling surfaces 11A face each other. The bearing ring 11 has a Vickers hardness of 700 HV or higher. The flatness of the race 11 on the raceway rolling surface 11A is about 10 μm.

  The needle roller 12 is made of steel and has a roller rolling surface 12A on the outer peripheral surface. As shown in FIG. 1, the needle roller 12 is disposed between the pair of raceways 11 so that the roller rolling surface 12A contacts the raceway rolling surface 11A.

  The cage 13 is made of, for example, resin, and holds the plurality of needle rollers 12 at a predetermined pitch in the circumferential direction of the raceway ring 11. More specifically, the retainer 13 has an annular shape and a plurality of pockets (not shown) formed at equal intervals in the circumferential direction. And the holder | retainer 13 accommodates the needle roller 13 in the said pocket.

  The plurality of needle rollers 12 are held by a cage 13 so as to roll freely on an annular raceway along the circumferential direction of the raceway ring 11. With the above configuration, the thrust needle roller bearing 1 is configured such that the pair of race rings 11 can rotate relative to each other. Further, the bearing ring 11 is manufactured by the manufacturing method of the bearing ring according to the present embodiment described below.

  Next, a method for manufacturing the bearing ring according to the present embodiment will be described. FIG. 2 is a flowchart schematically showing a method for manufacturing a bearing ring according to the present embodiment. FIG. 3 shows (A) the change over time of the current supplied to the steel material, (B) the change over time of the temperature of the steel material, (C) the stroke of the press machine, (D) in the method for manufacturing the bearing ring according to the present embodiment. ) Shows the operation of the hydraulic chuck, and (E) shows the operation of the first and second clamp parts. Hereinafter, the manufacturing method of the bearing ring according to the present embodiment will be described in the order of “S0 to S12” attached to FIGS. 2 and 3 while mainly referring to the flowchart of FIG. 2 and the time chart of FIG.

  First, a steel material that is a material for obtaining the race 11 is prepared (S0). Specifically, with reference to FIG. 4, a coil material 2 as a steel material is prepared. As shown in FIG. 4, the coil material 2 is obtained by winding a rolled thin plate steel material into a coil shape.

  The coil material 2 is made of steel containing, for example, 0.4% by mass or more of carbon. More specifically, the coil material 2 is, for example, SAE standard SAE1070, JIS standard S40C and S45C which are carbon steel materials for mechanical structures, JIS standard SUJ2 which is high carbon chromium bearing steel, and carbon tool steel material. JIS standard SK95, JIS standard SCM440 which is alloy steel for machine structure, JIS standard SKS11 which is alloy tool steel, JIS standard SUP13 which is spring steel, or JIS standard SUS440 which is stainless steel Made of steel. The coil material 2 is a thin steel material having a thickness of 2 mm or less.

  Next, a press machine 3 as a forming table for obtaining the race 11 from the coil material 2 is prepared (S0). First, the configuration of the press machine 3 will be described with reference to FIG. FIG. 5 shows a cross section along the vertical direction of the press machine 3 (the direction indicated by the double arrow in the figure). The press machine 3 mainly includes a press die 30, molding dies 31, 32, a first clamp portion 33A and a second clamp portion 33B, and an energizing terminal 34.

  The press die 30 has a cylindrical press portion 35. The press part 35 is a part for making the coil material 2 punched by contacting the coil material 2. Further, the press portion 35 is formed with a concave portion 35 </ b> A in which a tip portion is notched. The pressing die 30 is disposed so as to face the forming dies 31 and 32 in the vertical direction. The pressing die 30 can be stroked so as to approach the forming dies 31 and 32 or away from the forming dies 31 and 32 by a drive mechanism (not shown).

  FIG. 10 shows a state in which the press portion 35 is viewed in plan. As indicated by a broken line in FIG. 10, a water cooling circuit 35 </ b> B serving as a cooling water passage is provided in the press portion 35 along the circumferential direction. In FIG. 10, the arrow which shows the flow of a cooling water is attached | subjected. By cooling the press part 35 by circulating the cooling water in this manner, the coil material 2 can be rapidly cooled (die quench) when the press part 35 is brought into contact with the coil material 2.

  Referring to FIG. 5, the molding dies 31 and 32 are arranged so as to face the pressing die 30 in the vertical direction. As shown in FIG. 5, the molding die 31 has a cylindrical shape, and a convex portion 31 </ b> A that protrudes radially outward is formed on the outer peripheral portion thereof. The molding die 32 has a ring shape having a diameter larger than the diameter of the molding die 31. The molding die 32 is arranged outside the molding die 31 so as to have a gap between the molding die 32 and the molding die 31 in the radial direction. As shown in FIG. 7, when the press die 30 is stroked toward the molding dies 31 and 32, the press portion 35 is positioned in the gap between the molding dies 31 and 32.

  The first clamp part 33 </ b> A and the second clamp part 33 </ b> B are for fixing the coil material 2 in the press machine 3 and applying a tension to the coil material 2. 33 A of 1st clamp parts and the 2nd clamp part 33B are provided so that the state which clamps the coil material 2 from the said up-down direction, and the state which is not clamped are provided. The first clamp part 33A and the second clamp part 33B are only required to have an arbitrary configuration, but may be, for example, a hydraulic clamp or an air clamp.

  33 A of 1st clamp parts and the 2nd clamp part 33B are provided in the position which mutually opposes on both sides of the press die 30 and the shaping | molding dies 31 and 32 in the extension direction of the coil material 2. As shown in FIG. The first clamp part 33A is arranged on the supply side of the coil material 2 in the extending direction, and the second clamp part 33B is arranged on the discharge side of the coil material 2 in the extending direction.

  33 A of 1st clamp parts and the 2nd clamp part 33B are provided so that relative movement is possible in the mutually opposing direction (extension direction of the coil material 2). For example, each of the first clamp portion 33A and the second clamp portion 33B is a hydraulic clamp and includes a hydraulic cylinder (not shown), and is provided so as to be movable away from each other in the opposing direction by the hydraulic cylinder. Thereby, the first clamp part 33A and the second clamp part 33B are tensioned in the extending direction of the coil material 2 with respect to the coil material 2 arranged between the press die 30 and the molding dies 31 and 32. Can be applied. The tension that can be applied to the coil material 2 by the first clamp part 33A and the second clamp part 33B is more than 0 MPa and 500 MPa or less. Here, the tension is a stress in the length direction of the coil material 2 (stress for extending the coil material 2, specifically, the coil material 2 is clamped to energize and the deflection due to thermal expansion is extended. Therefore, the stress applied to the coil material 2).

  The energization terminal 34 is for supplying current to the coil material 2. More specifically, the energization terminal 34 is connected to a DC power supply or an AC power supply (not shown) and supplies a DC current or an AC current to the coil material 2. The coil material 2 can be heated by the heat generated by the current supply. The energizing terminal 34 is located, for example, on the inner side of the first clamp part 33A and the second clamp part 33B, and can contact a portion of the coil material 2 where tension is applied by the first clamp part 33A and the second clamp part 33B. Is provided. A press machine 3 having the above configuration is prepared.

  Next, the coil material 2 is installed in the press 3 (S1). Specifically, the coil material 2 is clamped by the first clamp part 33A and the second clamp part 33B of the press machine 3 (S2). Pressure for holding the coil material 2 is supplied to the first clamp part 33A and the second clamp part 33B.

  Next, tension is applied to the coil material 2 (S3). Specifically, referring to FIG. 5, at least one of first clamp portion 33 </ b> A and second clamp portion 33 </ b> B is relatively moved away from the other in the extending direction of coil material 2. Thereby, in the coil material 2, in the area | region located between the part currently hold | maintained at the 1st clamp part 33A and the 2nd clamp part 33B, respectively, relative to the 1st clamp part 33A and the 2nd clamp part 33B. A tension according to the amount of movement (the amount of change in the distance between the first clamp part 33A and the second clamp part 33B) is applied. The tension applied to the coil material 2 is, for example, more than 0 MPa and 500 MPa or less. The relative positional relationship between the first clamp part 33A and the second clamp part 33B is maintained at least until the press molding is completed (S9). That is, the tension applied to the coil material 2 is maintained at least during heating and press molding.

  Next, energization heating is started (S4). Specifically, referring to FIG. 6, first, the energizing terminal 34 is brought into contact with the coil material 2. Then, a current is supplied to the coil material 2 via the energization terminal 34. As a result, the coil material 2 is heated by the heat generation (joule heat) generated by the supply of current (energization heating). Then, after the temperature of the coil material 2 reaches the target temperature (S5), the coil material 2 is held at the target temperature for a certain time (S6). Thus, energization heating of the coil material 2 in the press machine 3 is completed (S7).

The heating temperature (target temperature) of the coil material 2 is a temperature equal to or higher than the A ₁ transformation point of the steel constituting the coil material 2 and is, for example, 1000 ° C. “A ₁ transformation point” refers to a point corresponding to a temperature at which the structure of the steel starts transformation from ferrite to austenite when the steel is heated. Therefore, the steel structure constituting the coil material 2 is transformed into austenite by the energization heating.

  Next, press molding of the coil material 2 is started (S8). Specifically, referring to FIG. 7, press die 30 strokes toward forming dies 31 and 32. Thereby, as shown in FIG. 7, the press part 35 contacts the coil material 2, and a part of coil material 2 is pierce | punched in the ring shape in the thickness direction of the said coil material 2 (S9). Thereby, the ring-shaped molded body 2A is obtained.

  Next, referring to FIG. 8, the pressing die 30 is further stroked toward the molding dies 31 and 32, whereby the inner peripheral portion of the molded body 2 </ b> A comes into contact with the convex portion 31 </ b> A of the molding die 31. Then, the pressing die 30 is stroked as it is to reach the bottom dead center (S10). Thereby, with reference to FIG. 9, the inner peripheral part of the molded body 2A is bent so as to face the thickness direction of the molded body 2A. In this manner, the forming process is performed on the molded body 2 </ b> A in the press 3.

Next, referring to FIG. 9, the molded body 2 </ b> A is held for a certain time in a state where it is in contact with the press 3 (press die 30, molding die 31, and base portion 36). At this time, the cooling water is supplied to the water cooling circuit 35B in the press die 30 as described above (FIG. 10). Thereby, the molded body 2A is quenched to a temperature equal to or lower than the M _s point, whereby a quenching process is performed. Here, the “M _s point (martensitic transformation point)” refers to a point corresponding to a temperature at which martensitization starts when the austenitized steel is cooled. As a result, the structure of steel constituting the formed body 2A is transformed into martensite. In this way, the quenching process (die quench) of the molded body 2A is completed (S11). Finally, the pressure supplied to the first clamp part 33A and the second clamp part 33B to hold the coil material 2 is unclamped (S12), and the coil material 2 and the quenching process that have become a scrap material are performed. The completed molded body 2A is taken out from the press machine 3. At this time, the tension applied to the coil material 2 is loosened by loosening the clamping force between the first clamp part 33A and the second clamp part 33B (S12). The track ring 11 is manufactured by the process as described above, and the method for manufacturing the track ring according to the present embodiment is completed.

The method of manufacturing the raceway according to the present embodiment is not limited to the above configuration.
The method of applying tension to the coil material 2 is not limited to the method of using the first clamp part 33A and the second clamp part 33B provided inside the press machine 3. For example, a method using the first clamp part 33A and the second clamp part 33B provided outside the press machine 3 may be used. In other words, both the first clamp part 33 </ b> A and the second clamp part 33 </ b> B may be provided outside the press machine 3.

  Further, instead of the first clamp part 33A in FIG. 5, a supply part 40 (an uncoiler) provided so as to be able to supply the coil material 2 to the press 3 as shown in FIG. 11 may be used. As shown in FIG. 4, a correction unit 50 (leveler) provided so as to be able to correct the distortion of the coil material 2 supplied from the supply unit 40 to the press machine 3 may be used. Even if it does in this way, tension | tensile_strength can be applied to the coil material 2 located between these and the 2nd clamp part 33B by driving at least one of these and the 2nd clamp part 33B.

  For example, by causing the supply unit 40 to perform a rewinding operation, tension can be applied between two points in the extending direction of the coil material 2 held by the supply unit 40 and the second clamp part 33B. Further, for example, by moving the second clamp portion 33B away from the correction portion 50 in the extending direction of the coil material 2, the extension of the coil material 2 held by the correction portion 50 and the second clamp portion 33B. Tension can be applied between two points in the direction.

  The heating method of the coil material 2 is not limited to energization heating, and at least one method selected from the group consisting of indirect resistance heating, induction heating, contact heat transfer, and far infrared heating can be employed. . Hereinafter, each heating method will be described in more detail.

Figure 13 Referring to (a) and (b), in the resistance heating, a method of heating an object 100 by the Joule heat generated by energizing the heating object 100 directly with a resistance R _1, resistors R There is a method of indirectly heating the object to be heated 100 disposed near the heating element 102 by Joule heat generated by energizing the heating element 102 having ₂ .

Figure 13 (a), the in the method of heating by energizing the heating object 100 directly, the current I supplied from the power source 101 with respect to the article to be heated 100 having a resistor R _1. As a result, the object to be heated 100 generates heat (P = R ₁ I ² ) due to the supply of the current I, and the object to be heated 100 is heated. In the present embodiment, the coil material 2 may be heated by heat generated by supplying a direct current from the energization terminal 34 to the coil material 2. Further, the coil material 2 may be heated by heat generated by supplying an alternating current from the energization terminal 34 to the coil material 2.

Further, referring to FIG. 13 (b), the in the method of indirectly heating an object 100, a current I is supplied from the power source 101 with respect to heating element 102 having a resistance _{R 2.} As a result, heat generation (P = R ₂ I ² ) is generated in the heating element 102 by supplying the current I, and the heating element 102 is heated. In the present embodiment, the heating element 102 may be supplied with a direct current or an alternating current.

  With reference to FIG. 14, in induction heating, alternating magnetic flux B is generated in article 100 to be heated by supplying an alternating current from coil power supply 104 to coil 103. Further, in the object to be heated 100, an eddy current I is generated in a direction to cancel the alternating magnetic flux B. Then, the object to be heated 100 is heated by heat generated by the eddy current I and the resistance R of the object to be heated 100.

  Referring to FIG. 15, in contact heat transfer, object to be heated 100 is heated by heat transfer from internal heating roll 105 and external heating roll 106. In far-infrared heating, far-infrared energy is given to the object to be heated by irradiating the object with far-infrared radiation. Thereby, the vibration between the atoms constituting the heated object is activated to generate heat, and the heated object is heated.

  Further, in the press machine 3, the first clamp part 33A and the second clamp part 33B are arranged in the direction along the surface of the coil material 2 and perpendicular to the extending direction (width direction). The molding dies 31 and 32 may be provided at positions facing each other.

  Moreover, in the manufacturing method of the bearing ring which concerns on this Embodiment, as shown in FIG. 9, it shape | molds in the press machine 3 by bending so that the inner peripheral part of 2 A of molded objects may face the thickness direction of 2 A of molded objects. Although the body 2A is formed, the present invention is not limited to this. Referring to FIG. 16, the outer peripheral portion (not the inner peripheral portion) of ring-shaped molded body 2 </ b> A may be molded. In this case, a convex portion 32 </ b> A that protrudes radially inward is formed on the inner peripheral surface of the molding die 32. For this reason, when the stroke of the die 30 for a press is performed similarly to the case of the said embodiment, the outer peripheral part of 2 A of ring-shaped molded objects contacts the said convex part 32A. Then, as in the case of the above-described embodiment, the stroke is performed until the pressing die 30 reaches the bottom dead center. Thereby, as shown in FIG. 16, the outer peripheral portion of the molded body 2A is bent so as to face the thickness direction of the molded body 2A. Even in this case, the molding 2A can be molded in the press 3 before the quenching process, and the same effect as in the case of the above embodiment can be obtained.

  Further, in the first clamp part 33A and the second clamp part 33B, one member that sandwiches and holds the coil material 2 in the vertical direction may also serve as the energizing terminal 34. In this case, in the first clamp part 33A and the second clamp part 33B, the one member and the other member located on the opposite side across the coil material 2 are made incapable of energization with the one member. ing. In this way, the configuration of the press machine 3 can be simplified.

  Next, the effect by the manufacturing method of the bearing ring which concerns on this Embodiment is demonstrated, referring a comparative example. First, a method for manufacturing a bearing ring in a comparative example will be described with reference to FIGS. Referring to FIG. 17, first, a coil material 200 is prepared in which a rolled thin plate steel material is wound in a coil shape. Next, referring to FIG. 18 and FIG. 19, the coil material 200 is placed on the die 310, and the die material 300 is stroked toward the die 310, whereby the coil material 200 is punched. Thereby, the ring-shaped molded body 200A is obtained. Next, referring to FIG. 20 and FIG. 21, the molded body 200 </ b> A is placed on the die 330, and the die 320 is stroked toward the die 330, whereby the inner peripheral portion of the molded body 200 </ b> A is molded. .

  Next, referring to FIG. 22, in the setup process before the heat treatment, a plurality of molded bodies 200 </ b> A are arranged in a state of being hung on the bar 410. Thereafter, referring to FIG. 22 and FIG. 23, these molded bodies 200 </ b> A are placed in a carburizing furnace 400, and carburizing treatment is performed on the molded bodies 200 </ b> A. Next, with reference to FIG. 24, the compact 200A after being carburized is cooled by applying a blast 420 to cool the compact 200A. Finally, with reference to FIG. 25, press tempering is performed on the molded body 200A after the quenching process in the tempering furnace 430. As described above, the manufacturing method of the bearing ring according to the comparative example includes many steps, and thus the manufacturing cost of the bearing ring increases.

  In contrast, in the raceway manufacturing method according to the present embodiment, each step of heating, punching, forming, and quenching of the coil material 2 is all performed as one step in the press 3. The Therefore, the manufacturing process can be further shortened as compared to the case where the above processes are performed separately as in the method of manufacturing the bearing ring in the comparative example. As a result, the manufacturing cost of the bearing ring can be further reduced, and a cheaper bearing ring can be provided.

  Furthermore, in the method for manufacturing a bearing ring according to the present embodiment, in the step of obtaining the bearing ring, heating and punching are performed in a state where tension is applied to the steel material in at least one direction along the surface of the steel material. . Therefore, compared with the case where the said heating and the said punching are performed in the state which has not applied tension with respect to steel materials in the process of obtaining the said bearing ring, the processing quality of the obtained bearing ring can be improved.

  It was confirmed that the bearing ring 11 manufactured by the manufacturing method of the bearing ring according to the present embodiment has high processing quality by evaluating as follows.

  Specifically, the track ring manufacturing method according to the present embodiment was implemented using the coil material 2 made of the steel material SAE1070 and the press machine 3 shown in FIG. In the press machine 3 shown in FIG. 26, the first clamp part 33A and one energization terminal 34 are connected to one cylinder 37, and the second clamp part 33B and the other energization terminal 34 are another cylinder. 37 is connected. Further, in the first clamp part 33A and the second clamp part 33B, the one member that sandwiches and holds the coil material 2 in the vertical direction and the energization terminal 34 can be in contact with the coil material 2 simultaneously. did. That is, in the first clamp part 33A and the second clamp part 33B, the coil member 2 is arranged on the other member located on the opposite side across the one member and the coil member 2, and the one member is lowered. By making it contact with the coil material 2, it was set as the structure which can contact the electricity supply terminal 34 with the coil material 2. FIG.

Using a press machine 3 shown in FIG. 26, in the state of applying a tension of 10MPa in the extending direction relative to the coil member 2, direct resistance heating coil material 2 to 1000 ° C. at a temperature above the A ₁ transformation point Then, die quenching was performed.

  In this way, the race 11 as shown in the photograph of FIG. 27 was manufactured. As a result of measuring the Vickers hardness on the plurality of bearing rings 11 (steel material: SAE1070) manufactured as described above, the average hardness was about 790 HV. In addition, when a part of the race 11 was cut, the cross section was subjected to nitral corrosion, and the cross section was observed with a micro structure with an optical microscope, a martensite structure as shown in the photograph of FIG. 28 was confirmed.

  Further, as a result of measuring the flatness of the race 11 using a talironde, the flatness was about 10 μm. On the other hand, in the step of obtaining the raceway in the present embodiment, the raceway obtained by performing the heating and punching without applying tension to the coil material 2 has a flatness of about 40 μm. there were.

  Thus, according to the bearing ring manufacturing method according to the present embodiment, the manufacturing process is shortened, and the bearing ring has high hardness and high processing quality by performing sufficient quenching treatment. It was confirmed that 11 could be manufactured.

  Here, although there is a part which overlaps with embodiment mentioned above, the characteristic structure of this invention is enumerated.

(1) The manufacturing method of the bearing ring which concerns on this Embodiment prepares the shaping | molding stand (press machine 3) for obtaining a bearing ring (11) from steel materials (coil material 2) and steel materials (2), a step of placing the steel (2) to the forming table (3), punching a portion of the steel (2) steel (2) after heating to a temperature above the a ₁ transformation point in the molding stage (3) in a ring Then, the step of obtaining the raceway ring (11) by quenching the ring-shaped steel material (2) in the forming table (3) is provided. In the step of obtaining the track (11), the heating and the punching are performed in a state where tension is applied to the steel material (2) in at least one direction along the surface of the steel material (2).

  In the raceway manufacturing method according to the present embodiment, all steps of heating, punching and quenching of the steel material (2) are performed as one step in the forming table (3). Therefore, compared with the case where the said process is implemented separately like the conventional manufacturing method of a bearing ring, a manufacturing process can be shortened more. As a result, it is possible to further reduce the manufacturing cost of the bearing ring, and it is possible to provide a less expensive bearing ring (11). Thus, according to the manufacturing method of the raceway according to the present invention, the manufacturing process of the raceway can be further shortened.

  Furthermore, in the manufacturing method of the raceway ring according to the present embodiment, in the step of obtaining the raceway ring (11), a tension is applied to the steel material (2) in at least one direction along the surface of the steel material (2). Then, heating and punching are performed. Therefore, compared with the case where the said heating and the said punching are performed in the state which has not applied tension with respect to steel materials in the process of obtaining the said bearing ring, the processing quality of the obtained bearing ring (11) can be improved.

More specifically, without applying the tension to the steel, when heated to a temperature not lower than the A ₁ transformation point in the molding stage the steel is deformed by heating the steel occurs. In particular, since the raceway of the thrust needle roller bearing is thin as described above, it is likely to be deformed by heating. When such deformation occurs in the steel material, there is a possibility that the deformed portion comes into contact with a part of the forming table (press machine 3) (for example, the forming die 32). When such contact occurs, the heat applied to the steel material is dissipated from the contacted part to the forming table, so that the steel material (particularly the part to be processed. For example, the part held by the two clamp parts respectively. In some cases, heat distribution occurs in the sandwiched portion), and a region that is not heated to a temperature equal to or higher than the A ₁ transformation point may be generated. As a result, the steel material in the molding base without applying the tension to the steel is heated to the A ₁ transformation point or higher, and more stamping and quenching treatment has been races obtained, the above deformation There may be a case where sufficient processing quality is not obtained due to the defective heating.

  Furthermore, when the steel material is punched on the forming table without applying the above tension to the steel material, the steel material is punched while being deformed by heating. There was a problem that decreased.

On the other hand, in the method of manufacturing the bearing ring according to the present embodiment, in the step of obtaining the bearing ring (11), tension is applied to the steel material (2) in at least one direction along the surface of the steel material (2). Since the heating is performed in a heated state, deformation of the steel material (2) due to heating can be reduced or suppressed. As a result, it is possible to prevent the steel material (2) and the forming table (3) from contacting each other, thereby suppressing heat dissipation from the steel material (2) to the forming table (3) through a part of the steel material (2). are, can be heated to the temperature across the a ₁ transformation point or above of the working target portion of the steel (2).

Furthermore, in the method for manufacturing the raceway ring according to the present embodiment, in the step of obtaining the raceway ring (11), the steel material (2) is applied to the forming base (3) in a state where the tension is applied to the steel material (2). since punching is performed, the whole can perform punching with respect to steel deformed is heated to a temperature not lower than the a ₁ transformation point is reduced or suppressed (2). As a result, the bearing ring (11) manufactured by the manufacturing method of the bearing ring according to the present embodiment is processed with high accuracy while suppressing a decrease in punching accuracy. In addition, the variation of the processing quality of the raceway ring (11) is reduced.

  (2) In the manufacturing method of the raceway, the tension is more than 0 MPa and 500 MPa or less.

  Thereby, the deformation of the steel material (2) due to heating can be sufficiently reduced or suppressed. As a result, the bearing ring (11) thus obtained is inexpensive and has high processing quality.

  (3) In the step of obtaining the bearing ring of the method for manufacturing the bearing ring, the steel member (2) is provided with a supply unit (40) provided so as to be able to supply the steel member (2) to the forming table (3). The correction part (50) provided so that distortion of the steel material supplied from the part (40) to the forming table (3) can be corrected, and the first clamp part provided so as to hold a part of the steel material (2) At least one of (33A), and the second clamp part (33B) which is located on the opposite side to the one and the forming table (3) and is capable of holding the other part of the steel material (2). And tension is applied.

  Thereby, at least any one of a supply part (40), a correction | amendment part (50), and a 1st clamp part (33A) and the 2nd clamp part (33B) are each holding the steel material (2). By moving relatively away from each other, tension can be applied to the steel material (2) on which the heating and punching steps are performed in the forming table (3). In this way, it is possible to obtain a bearing ring (11) that is inexpensive and has high processing quality.

  (4) In the above-described method for manufacturing a race, the ring-shaped steel material (ring-shaped molded body 2A) may be subjected to a molding process in the molding table (3) before the quenching process. In the forming process, the inner peripheral portion or the outer peripheral portion of the ring-shaped steel material (2A) may be bent so as to face the thickness direction of the ring-shaped steel material (2A).

  Thereby, each process of heating of a steel material (2), stamping, a shaping | molding process, and a quenching process can be implemented as one process in a shaping | molding stand (3). As a result, the manufacturing process of the race (11) can be further shortened. In addition, it is possible to manufacture the thrust bearing race (11) in which the ring-shaped inner periphery or outer periphery is bent in the thickness direction.

  (5) In the method for manufacturing a race, the steel material (2) may contain 0.4% by mass or more of carbon. The steel material (2) may have a thickness of 2 mm or less. The steel material (2) may be punched into a ring shape in the thickness direction.

  Thereby, the bearing ring (11) which has high hardness after a quenching process can be manufactured. Moreover, by using such a relatively thin steel material (2), the steel material (2) can be easily punched, and sufficient quenching can be performed on the steel material (2).

  (6) In the method for manufacturing a bearing ring, the steel material (2) is heated by at least one method selected from the group consisting of current heating, indirect resistance heating, induction heating, contact heat transfer, and far infrared heating. Also good. Thus, in the manufacturing method of the above-mentioned bearing ring, any heating method can be adopted as a heating method of the steel material (2). In the energization heating, the steel material (2) may be heated by heat generated by supplying a direct current or an alternating current to the steel material (2). Thus, in energization heating, both direct current and alternating current can be adopted.

  (7) In the above method for manufacturing a bearing ring, a bearing ring (11) having a hardness of 700 HV or more may be obtained. Thus, in the manufacturing method of the above-mentioned bearing ring, while shortening the manufacturing process and performing a sufficient quenching process on the steel material (11), the bearing ring having a high hardness after the quenching process. (11) can be manufactured.

  Although the embodiment of the present invention has been described as above, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The track ring manufacturing method of the present invention can be applied particularly advantageously in a track ring manufacturing method that requires a shorter manufacturing process. Moreover, the bearing ring of the present invention can be applied particularly advantageously to a bearing ring that requires a reduction in manufacturing cost.

  DESCRIPTION OF SYMBOLS 1 Thrust needle roller bearing, 2 Coil material, 3 Press machine, 11 Race ring, 11A Raceway rolling surface, 12 Needle roller, 12A Rolling surface, 13 Cage, 30 Press die, 31, 32 Molding die, 31A , 32A Convex part, 33A First clamp part, 33B Second clamp part, 34 Current terminal, 35 Press part, 35A Concave part, 35B Water cooling circuit, 36 Base part, 40 Supply part, 50 Correction part, 100 Object to be heated, 101 Power source, 102 heating element, 103 coil, 104 AC power source, 105 internal heating roll, 106 external heating roll, B alternating magnetic flux, I current (eddy current).

Claims (7)

A method of manufacturing a bearing ring,
Preparing a steel plate and a forming table for obtaining the raceway from the steel material;
Installing the steel material on the forming table;
The punching in the molding stage the steel part of the steel after heating to a temperature above the A ₁ transformation point in a ring, then the bearing ring by the quenching of the ring of the steel in the molding platform And a step of obtaining
In the step of obtaining the bearing ring, the heating and the punching are performed in a state where tension is applied to the steel material in at least one direction along the surface of the steel material.   The raceway manufacturing method according to claim 1, wherein the tension is greater than 0 MPa and less than or equal to 500 MPa.   In the step of obtaining the bearing ring, the steel material is provided with a supply unit (uncoiler) provided so that the steel material can be supplied to the forming table, and the distortion of the steel material supplied from the supplying unit to the forming table is corrected. At least one of an orthodontic portion (leveler) provided so as to be able to hold a part of the steel material, and the one and the forming table located on the opposite side of the forming table. The method of manufacturing a bearing ring according to claim 1, wherein the tension is applied using a second clamp portion provided to be able to hold the other part of the steel material. Prior to the quenching treatment, the ring-shaped steel material is subjected to a forming process in the forming table,
The track according to any one of claims 1 to 3, wherein in the forming process, an inner peripheral portion or an outer peripheral portion of the ring-shaped steel material is bent so as to face a thickness direction of the ring-shaped steel material. A manufacturing method of a ring.   5. The steel material according to claim 1, wherein the steel material includes 0.4% by mass or more of carbon, has a thickness of 2 mm or less, and is stamped into a ring shape in the thickness direction. Method for manufacturing the raceway.   In the step of obtaining the bearing ring, the steel material is heated by at least one method selected from the group consisting of current heating, indirect resistance heating, induction heating, contact heat transfer, and far infrared heating. The manufacturing method of the bearing ring of any one of Claims 1-5.   The method for manufacturing a bearing ring according to any one of claims 1 to 6, wherein the bearing ring having a hardness of 700 HV or more is obtained.