Method of manufacturing taper bearing

Abstract

To provide a method for manufacturing a taper bearing excellent in material yield.SOLUTION: The method for manufacturing the taper bearing is a method for manufacturing a taper bearing having an outer ring and an inner ring having a maximum outer diameter equal to or larger than a minimum inner diameter of the outer ring. In this manufacturing method, a blank 14 is forged into a formed product 16 having a shape including a central part 16A having a shape of a primary intermediate material 18 to be worked into an inner ring and an outer ring part 16A positioned outside the central part 16B and having a shape of an outer ring preform 6 to be worked into an outer ring. The center part 16A is punched from the outer ring part 16B of the molded article 16, and separated into an outer ring preform 6 obtained from the outer ring part 16B and a primary intermediate material 18 obtained from the center part 16A. A through-hole 20B is formed in the radial center of the primary intermediate material 18 to obtain a secondary intermediate material 20. A diameter-expanding punch is passed through the 20B of the through-hole of the secondary intermediate material 20 to expand the outside diameter of the secondary intermediate material 20 to obtain an inner ring preform 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This specification discloses a method for manufacturing a tapered bearing. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2004-290983 discloses a method for manufacturing a tapered bearing having an outer ring and an inner ring with a maximum outer diameter equal to or greater than the minimum inner diameter of the outer ring. In this manufacturing method, a tower is formed by stacking a shaped portion of the inner ring blank to be machined into the inner ring and a shaped portion of the outer ring blank to be machined into the outer ring in the axial direction. The inner ring blank and the outer ring blank are obtained from this tower. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-290983 Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacturing method disclosed in JP 2004-290983 A, the portion between the inner ring blank and the outer ring blank is removed by cutting, separating the inner ring blank and the outer ring blank. In this manufacturing method, the tower is formed into a shape that includes the portion removed by cutting. This manufacturing method has a low material yield.

[0005] The applicant's intention is to provide a method for manufacturing a tapered bearing that is excellent in material yield. [Means for solving the problem]

[0006] The method for manufacturing a tapered bearing disclosed in this specification is a method for manufacturing a tapered bearing having an outer ring and an inner ring having a maximum outer diameter equal to or greater than the minimum inner diameter of the outer ring. This manufacturing method is forging a blank into a formed product having a shape including a central portion having the shape of a primary intermediate material to be processed into the inner ring and an outer annular portion located outside the central portion and having the shape of an outer ring base to be processed into the outer ring; punching the central portion from the outer ring portion of the molded product, and separating the outer ring blank obtained from the outer ring portion and the primary intermediate material obtained from the central portion; a through hole is formed in the radial center of the primary intermediate member to obtain a secondary intermediate member; a diameter-expanding punch is passed through the through hole of the secondary intermediate material to expand the outer diameter of the secondary intermediate material, thereby obtaining a blank for the inner ring.

[0007] Preferably, the through hole of the secondary intermediate member is formed by punching out the radial center of the primary intermediate member.

[0008] Preferably, before the diameter-expanding punch is passed through the through hole of the secondary intermediate material, the inner peripheral surface of the secondary intermediate material surrounding the through hole is machined. [Effects of the Invention]

[0009] This method of manufacturing a tapered bearing has an excellent material yield. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram showing an outer ring blank to be machined into an outer ring and an inner ring blank to be machined into an inner ring, which are obtained by a method for manufacturing a tapered bearing according to one embodiment. [Figure 2] FIG. 2 is an explanatory diagram of an intermediate material obtained in the manufacturing process of the outer race blank and the inner race blank of FIG. [Figure 3] FIG. 3 is a cross-sectional view of a molded article obtained from the blank of FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the outer ring blank and the inner ring primary intermediate material obtained by separating the molded product of FIG. [Figure 5] FIG. 5 is a cross-sectional view showing a secondary intermediate piece of an inner ring obtained from the primary intermediate piece of FIG. [Figure 6]FIG. 6 is an explanatory diagram showing a molding machine for molding the secondary intermediate material of FIG. 5 and an inner ring blank molded by the molding machine. [Figure 7] FIG. 7 is a flowchart of a method for manufacturing a tapered bearing according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, preferred embodiments will be described in detail with reference to the drawings as appropriate.

[0012] FIG. 1 shows a cross section of an outer ring blank 6 that is machined into the outer ring 4 of a tapered bearing 2, and an inner ring blank 10 that is machined into the inner ring 8. In FIG. 1, the shape of the outer ring blank 6 is represented by a solid line, and the shape of the outer ring 4 is represented by a two-dot chain line. The shape of the inner ring blank 10 is also represented by a solid line, and the shape of the inner ring 8 is represented by a two-dot chain line. In FIG. 1, the diagonal lines in the cross section of the outer ring blank 6 and the cross section of the inner ring blank 10 have been omitted in order to show the shapes of the outer ring 4 and inner ring 8. The outer ring 4 and outer ring blank 6 are ring-shaped, and the inner ring 8 and inner ring blank 10 are also ring-shaped.

[0013] In Figure 1, the double-headed arrow D4 represents the minimum inner diameter of the inner peripheral surface 4A of the outer ring 4, and the double-headed arrow D6 represents the minimum inner diameter of the outer ring blank 6. The double-headed arrow D8 represents the maximum outer diameter of the outer peripheral surface 8A of the inner ring 8. The double-headed arrow D10A represents the inner diameter of the inner ring blank 10, and the double-headed arrow D10B represents the outer diameter of the inner ring blank 10. In this tapered bearing 2, the maximum outer diameter D8 of the inner ring 8 is equal to or greater than the minimum inner diameter D4 of the outer ring 4.

[0014] Figure 2 shows an outer ring blank 6, an inner ring blank 10, and a billet 12 that is processed into the outer ring blank 6 and the inner ring blank 10. Figure 2 also shows intermediate materials in the process of processing the billet 12 into the outer ring blank 6 and the inner ring blank 10. Figure 2 shows, as intermediate materials, a blank 14 obtained from the billet 12, a formed product 16 obtained from the blank 14, the outer ring blank 6 and a primary intermediate material 18 obtained from the formed product 16, a secondary intermediate material 20 obtained from the primary intermediate material 18, and the inner ring blank 10 obtained from the secondary intermediate material 20. Figure 2 also shows so-called pits 22 that have been removed from the secondary intermediate material 20.

[0015] FIG. 3 shows a cross section of the molded article 16. The molded article 16 includes a central portion 16A having the shape of the primary intermediate material 18 and an outer annular portion 16B having the shape of the outer ring blank 6. The molded article 16 has a disk-like shape. In the radial direction, the molded article 16 has a shape in which the central portion 16A located on the inside is surrounded by the outer annular portion 16B located on the outside. In FIG. 3, the imaginary boundary between the central portion 16A and the outer annular portion 16B is indicated by a two-dot chain line.

[0016] FIG. 4 shows the outer ring blank 6 obtained from the molded product 16, and the primary intermediate member 18. The outer ring blank 6 and the primary intermediate member 18 are obtained by punching the primary intermediate member 18 out of the molded product 16. The outer ring blank 6 has an inner circumferential surface 6A where the primary intermediate member 18 has been punched out. The primary intermediate member 18 is disk-shaped. The primary intermediate member 18 has an outer circumferential surface 18A formed by punching. The double-headed arrow D18 in FIG. 4 indicates the outer diameter at the outer circumferential surface 18A. The outer diameter D18 of the primary intermediate member 18 and the inner diameter D6 of the outer ring blank 6 are approximately the same size.

[0017] FIG. 5 shows the secondary intermediate material 20 obtained from the primary intermediate material 18, together with the punched-out and removed punctures 22. The secondary intermediate material 20 is ring-shaped. The secondary intermediate material 20 has an inner circumferential surface 20A from which the punctures 22 have been punched out. The secondary intermediate material 20 has a through hole 20B in the center in the radial direction. The secondary intermediate material 20 and the punctures 22 are formed by punching out the center portion of the primary intermediate material 18. The double-headed arrow D20A in FIG. 5 indicates the inner diameter of the inner circumferential surface 20A surrounding the through hole 20B, and the double-headed arrow D20C indicates the outer diameter of the outer circumferential surface 20C.

[0018] 6 shows a molding machine 24 that sizes the secondary intermediate material 20, and the inner ring blank 10 obtained by sizing in the molding machine 24. The molding machine 24 is equipped with a die 24A that supports the inner ring blank 10 from below, an expanding punch 24B that is passed through a through hole 10B in the inner ring blank 10, and a stripper 24C that is positioned above the inner ring blank 10 and presses the inner ring blank 10 when the expanding punch 24B is removed. In this molding machine 24, the outer peripheral surface 10C of the inner ring blank 10 is not supported and is in a free state.

[0019] Fig. 7 shows a flowchart of a method for manufacturing the tapered bearing 2 having the outer ring 4 and inner ring 8 of Fig. 1. The method for manufacturing the tapered bearing 2 will now be described with reference to Fig. 2 to Fig. 7. Fig. 2 also shows a separating punch 26 and a punch 28 used in this manufacturing method.

[0020] A steel bar (not shown) is heated, and a billet 12 (shown in FIG. 2) is cut from the high-temperature steel bar to prepare a material (STEP 1). The billet 12 is upset forged (STEP 2). This upset forging pressurizes the billet 12 in the axial direction, expanding its diameter and producing a disk-shaped blank 14. The blank 14 is then forged (STEP 3). This forging produces a formed product 16 from the blank 14. A central portion 16A of the formed product 16 (shown in FIG. 3) is punched out with a separating punch 26, separating the blank into the outer ring blank 6 and a primary intermediate piece 18 (shown in FIG. 4) (STEP 4). The center of the primary intermediate piece 18 is punched out with a punch 28, removing a punch waste 22 as shown in FIG. 5, and a secondary intermediate piece 20 is produced (STEP 5). In this manufacturing method, upset forging (STEP 2), forging (STEP 3), separation (STEP 4), and punch removal (STEP 5) are performed by hot forging. After cooling, the inner peripheral surface 20A of the secondary intermediate material 20 is machined to remove the surface layer of the inner peripheral surface 20A (STEP 6). The secondary intermediate material 20 with the machined inner peripheral surface 20A is sized at room temperature in a forming machine 24 shown in FIG. 6 (STEP 7). This sizing (STEP 7) is cold forging. The secondary intermediate material 20 is set in a die 24A shown in FIG. 6, and an expanding punch 24B is passed through a through hole 20B of the secondary intermediate material 20. By passing this expanding punch 24B, the inner diameter D20A and outer diameter D20C of the secondary intermediate material 20 shown in FIG. 5 are expanded, and the inner ring blank 10 is obtained. This inner ring blank 10 is machined (STEP 8) to obtain the inner ring 8. Also, the outer ring blank 6 obtained from the molded product 16 is machined (STEP 9) to obtain the outer ring 4.

[0021] In this method of manufacturing a tapered bearing 2, the outer ring blank 6 is obtained from the outer annular portion 16B of the molded product 16, and the primary intermediate piece 18 is obtained from the central portion 16A of the molded product 16. For this reason, the outer diameter 18D of the primary intermediate piece 18 cannot be larger than the inner diameter D6 of the outer ring blank 6. In this method of manufacturing a tapered bearing 2, a secondary intermediate piece 20 having a through hole 20B is obtained from the primary intermediate piece 18, and an expanding punch 24B is passed through this through hole 20B to expand the inner diameter D20A and outer diameter D20C of the secondary intermediate piece 20. As a result, even if the outer diameter D18 of the primary intermediate piece 18 is smaller than the inner diameter D6 of the outer ring blank 6, the outer diameter D10B of the inner ring blank 10 can be larger than the inner diameter D6 of the outer ring blank 6. This manufacturing method can manufacture a tapered bearing 2 having an inner ring 8 with a maximum outer diameter D8 that is equal to or larger than the minimum inner diameter D4 of the outer ring 4.

[0022] The manufacturing method for this tapered bearing 2 involves forging a blank 14 into a formed product 16 having a shape including a central portion 16A having the shape of a primary intermediate piece 18 to be processed into the inner ring 8, and an outer annular portion 16B having the shape of an outer ring blank 6 to be processed into the outer ring 4. This manufacturing method then punches out the central portion 16A from the outer annular portion 16B, and separates the formed product 16 into the outer ring blank 6 obtained from the outer annular portion 16B and the primary intermediate piece 18 obtained from the central portion 16A. Because this manufacturing method punches out the central portion 16A from the outer annular portion 16B, there is no need to remove the area between the outer annular portion 16B and the central portion 16A by cutting. This manufacturing method has an excellent material yield.

[0023] This manufacturing method is excellent in material yield when manufacturing a tapered bearing 2 having an outer ring 4 and an inner ring 8 with a maximum outer diameter D8 that is equal to or greater than the minimum inner diameter D4 of the outer ring 4. Because this manufacturing method for a tapered bearing 2 is excellent in material yield, it is possible to reduce the mass of the blank 14 that is formed into the formed product 16. Therefore, this manufacturing method can reduce the mass of the billet 12 that is forged into the blank 14.

[0024] This manufacturing method for a tapered bearing 2 involves expanding the inner diameter D20A and outer diameter D20C of the secondary intermediate piece 20 to obtain the inner ring blank 10. Therefore, the inner diameter D20A of the secondary intermediate piece 20 is smaller than the inner diameter D10A of the inner ring blank 10 after the expansion. This manufacturing method can reduce the outer diameter of the punch 22 that is punched out to form the through hole 20B in the secondary intermediate piece 20. This manufacturing method can also reduce the mass of the punch 22, which is an unnecessary portion. From this perspective, this manufacturing method is excellent in terms of material yield.

[0025] In the method for manufacturing this tapered bearing 2, a decarburized layer is formed on the inner circumferential surface 20A of the secondary intermediate material 20 by hot rolling. In this manufacturing method, the inner circumferential surface 20A is machined (STEP 6) before sizing (STEP 7) in which an expanding punch 24B is passed through the through hole 20B of the secondary intermediate material 20. In this manufacturing method, the decarburized layer on the inner circumferential surface 20A of the secondary intermediate material 20 can be removed by machining. After sizing, there is no need to machine the inner circumferential surface 10A of the inner ring blank 10 to remove the decarburized layer. By passing the expanding punch 24B through the inner circumferential surface 10A of this inner ring blank 10 after machining, it is possible to omit some or all of the finishing process after sizing. From this viewpoint, in this manufacturing method, it is preferable to machine the inner peripheral surface 20A (STEP 6) before sizing in which the diameter-enlarging punch 24B is passed through the through-hole 20B of the secondary intermediate material 20 (STEP 7). [Industrial Applicability]

[0026] The manufacturing method described above can be widely applied to tapered bearings having an outer ring and an inner ring having a maximum outer diameter equal to or greater than the minimum inner diameter of the outer ring. [Explanation of symbols]

[0027] 2. Tapered bearing 4. Outer ring 6. Outer ring base 8. Inner circle 10. Inner ring base 14...Blank 16...Molded products 18...Primary intermediate material 20 Secondary intermediate material 20A...Inner surface 24B Expanding Punch

Claims

1. 1. A method for manufacturing a tapered bearing having an outer ring and an inner ring having a maximum outer diameter equal to or greater than the minimum inner diameter of the outer ring, comprising: forging a blank into a formed product having a shape including a central portion having the shape of a primary intermediate material to be processed into the inner ring and an outer annular portion located outside the central portion and having the shape of an outer ring base to be processed into the outer ring; punching the central portion from the outer ring portion of the molded product, and separating the outer ring blank obtained from the outer ring portion and the primary intermediate material obtained from the central portion; a through hole is formed in the radial center of the primary intermediate member to obtain a secondary intermediate member; a diameter-expanding punch is passed through the through hole of the secondary intermediate material to expand the outer diameter of the secondary intermediate material, thereby obtaining a blank for the inner ring.

2. The method for manufacturing a tapered bearing according to claim 1 , wherein the through hole of the secondary intermediate piece is formed by punching out the radial center of the primary intermediate piece.

3. 3. The method for manufacturing a tapered bearing according to claim 1, wherein an inner peripheral surface of the secondary intermediate material surrounding the through hole is machined before the enlarging punch is passed through the through hole of the secondary intermediate material.

Images