JPH06170479A - Manufacture of outer ring of ball bearing - Google Patents

Abstract

PURPOSE:To obtain the outer ring of ball bearing having excellent durbility so as an orbit surface and metal flows are almost parallel. CONSTITUTION:After heating a columnar steel billet 1 having a first prescribed height H forming plural metal flows in the axial direction of the cross section, upsetting it a first upset working material 4 having a second prescribed height H1 is manufactured. Successively, after turning over the first upset working material 4, further upsetting it to the first upset working material 4 a second upset working material 5 having a third prescribed height H2 is manufactured. Therefore, by executing a uniform middle pressure on upper and lower parts, punching at the center part and rolling work, the outer ring is manufactured. Further, upset ratio as the rate of the reducing quantity (H-H2) to the first prescribed height H of the columnar steel billet 1 is made to 0.50-0.65.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an outer ring for a ball bearing, and more particularly to a method for manufacturing an outer ring for a ball bearing, which is manufactured by plastic working the outer ring for a ball bearing.

[0002]

2. Description of the Related Art When an outer ring for a ball bearing is manufactured by plastic working, conventionally, a cylindrical steel billet is held by an upper mold and a lower mold, and the cylindrical steel billet is upset. After press-pressing the center portion of the plane from above to reduce the thickness of the center portion of the plane, punching is performed to punch the inside to manufacture a ring-shaped workpiece, and then the ring-shaped workpiece is manufactured. The outer ring was manufactured by holding the outer peripheral surface of the above with a forming roll, rolling with a mandrel roll, and then cutting by machining.

[0003]

In the above conventional manufacturing method, the cylindrical steel billet is heated and then set up, but the lower die is heated more than the upper die. Since the contact time of the steel billet is long, the temperature distribution is not uniform, and the temperature becomes lower as it goes downward. Therefore, when the upsetting step is performed once as in the above conventional manufacturing method, as shown in FIG. 4, the metal fiber flow after upsetting (hereinafter,
.., which are simply referred to as "metal flow", are asymmetrical in the vertical direction. Further, since the middle pressing is performed from one direction, the asymmetrical shape of the metal flows 51 ... Is increased. For this reason, the metal flow 51 of the work does not match the raceway surface of the bearing outer ring when the rolling process is finally performed, and the metal flow 51 ... Is cut when the work is formed by machining. There is a problem that the bearing life is shortened by being exposed on the outer ring raceway surface.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing an outer ring for a ball bearing, which can obtain an outer ring for a ball bearing having excellent durability.

[0005]

In order to achieve the above object, a method of manufacturing an outer ring for a ball bearing according to the present invention is provided with a first predetermined height H in which a large number of metal flows are formed in the axial direction of a cross section.
Is heated to a hot forging zone and then upset to produce a first upset having a second predetermined height H1, and then the first upset is After turning over, the first upset workpiece is upset to a third predetermined height H.
2 is manufactured, and thereafter, the center portion of the plane of the second upset workpiece is evenly pressed from above and below to form an intermediate pressing portion, and then the intermediate pressing portion is formed. The portion is hollowed out to form a ring-shaped workpiece, and then the ring-shaped workpiece is subjected to rolling processing, and the height of the cylindrical steel billet with respect to the first predetermined height H of the cylindrical steel billet. The upsetting ratio, which is the ratio of the reduction amount (H-H2), is 0.50 to 0.
The feature is that it is set to 65.

[0006]

According to the above method, the first upset product manufactured by upsetting the heated cylindrical billet is inverted, and upset is performed again to form the second upset product. Since it is manufactured, the thermal symmetry of the product (second upsetting work) can be maintained, the symmetry in the axial direction of the metal flow can be ensured, and the metal inside the work can be secured. The flow can be curved, and the raceway surface shape of the outer ring and the metal flow can be matched.

The height of the steel billet before installation (first
H), the height of the second upset workpiece (third predetermined height) is H2, and the upset ratio η is defined by the mathematical expression (1), η = (H−H2) / H (1) When the upsetting ratio η is small, the metal flow 42 has a small curvature, and as shown in FIG. 3A, after the rolling process, the metal flow 42 ... The curvature is too small to match the raceway surface. On the other hand, upset rate η
3b, the curvature of the metal flow 42 is large, and after the rolling process, the metal flow 42 at the location corresponding to the raceway surface is excessively curved and the metal flow 42 ... It does not match. Therefore, the upset ratio η has an optimum range. In the present invention, the upsetting ratio η is set to 0.50 to 0.65 based on the experimental results and the like, so that it is possible to form a metal flow that matches the raceway surface of the outer ring.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 (I) to (III) and 2 (IV) to (V
II) is a manufacturing process chart sequentially showing one embodiment of a method for manufacturing an outer race for a ball bearing according to the present invention.

Each drawing shows the outline of the cross section in the axial direction (up and down direction of the drawing) of the steel billet which is the work during the manufacturing process, and the one-dot chain line shows the central axis.

In FIG. 1 (I), reference numeral 1 denotes a cylindrical steel billet having a height H of 102 mm formed from a material made by forging (hereinafter referred to simply as "steel billet"). 1 (I) and (a) are plan views, and FIGS. 1 (I) and 1 (b) are shown in FIG. 1 (I), in which a large number of metal flows 2 are formed and are parallel to the axial direction of the steel billet 1. It has been stretched.

In the present manufacturing method, first, the steel billet 1 is heated in the hot forging area and then held by the first upper die 3a and the lower die 3b as shown in FIG. 1 (II). , The first upsetting is performed by pressing from above with a predetermined pressure to produce a first upset 4 having a height H1 of, for example, 73 mm, and then the first upset 4 is inverted. Then, the first upper mold 3a and the lower mold 3b are held again, and the second upset ratio η defined by the mathematical expression (1) is set in the range of 0.50 to 0.65. Upsetting is performed to manufacture the second upset workpiece 5.

Η = (H−H2) / H (1) Here, H2 is the height of the second upsetting workpiece 5. In this embodiment, H2 = 44 mm, so the upset ratio η
Is 0.57 according to the equation (1).

That is, in the hot forging process as in this embodiment, the first lower die 3a has the first upper die as described in the section [Problems to be Solved by the Invention]. Type 3
Since the contact time with the steel billet 1 is longer than that in b, the temperature distribution inside the steel billet 1 becomes non-uniform and the temperature becomes lower as it goes downward, so the upsetting process is divided into two, By reversing the object to be machined (workpiece) between the upsetting and the second upsetting, it is possible to avoid the asymmetric metal flow 2 ... Due to the non-uniformity of the temperature distribution. Further, due to the reason described in the section of [Operation], the upsetting ratio η is within a predetermined range (0.50 to 0.65) of 0.57.
Therefore, the outer ring raceway surface 16 (see FIG. 2 (VI
It is formed so that the shape of (see I)) and the curved shape of the metal flow 2 after the rolling process are relatively well matched.

Next, the second upsetting work 5 is turned over again, and as shown in FIG. 2 (IV), the second upsetting work is performed by the second upper die 7a and the second lower die 7b. Holding the center portion of the plane of the workpiece 5 and pressurizing it with a predetermined uniform pressure in the arrow A direction and the arrow B direction to perform intermediate pressing, the thickness of the central portion is reduced to form the intermediate pressing portion 9. Then, as shown in FIG. 2 (V), the through hole 10 is formed by punching by punching or the like.
The ring-shaped processed product 11 in which is formed is molded.

Next, as shown in FIG. 2 (VI), the outer periphery of the ring-shaped workpiece 11 is held by a forming roll 13 having a pressing surface 12 conforming to the shape of the raceway surface, and the ring-shaped workpiece 11 is held. The inner peripheral surface of 11 is pressed by the mandrel roll 14 in the direction of arrow C to increase the hole diameter of the through hole 10, and when the hole diameter reaches a predetermined value, the rolling process ends. This allows
A metal flow 2 ... Is formed in conformity with the raceway surface shape.

Finally, as shown in FIG. 2 (VII), an outer ring 15 having a metal flow 2 ...

In the outer ring 15 thus manufactured, it is possible to prevent the cut surface of the metal flow 2 ... from being exposed to the raceway surface, the life of the outer ring 15 can be extended, and the durability of the bearing can be improved. It is possible to improve.

It is needless to say that the present invention is not limited to the above-mentioned embodiment and can be modified within the scope of the invention. For example, if the cooling effect of the object to be processed is large, it goes without saying that the object to be processed may be reheated between the respective steps and each predetermined step may be performed.

[0020]

As described in detail above, in the method for manufacturing the outer ring for the ball bearing according to the present invention, the cylindrical steel billet having the first predetermined height H in which a large number of metal flows are formed in the axial direction of the cross section. Is heated to a hot forging zone and then upset is performed to produce a first upset workpiece having a second predetermined height H1, and then the first upset workpiece is inverted before the first upset workpiece is inverted. Of the upset workpiece to produce a second upset workpiece having a third predetermined height H2, and thereafter, the plane center portion of the second upset workpiece is moved upward and downward. To form a middle pressed portion, and then the middle pressed portion is hollowed out to form a ring-shaped workpiece, and then the ring-shaped workpiece is subjected to rolling processing, so that the symmetry of the metal flow is maintained. The outer ring that can be secured and has a metal flow that relatively matches the raceway shape is manufactured. It can, it is possible to enhance the durability of the bearing.

The height reduction amount (H) of the cylindrical steel billet with respect to the first predetermined height H of the cylindrical steel billet.
Since the upsetting ratio, which is the ratio of −H2), is set to 0.50 to 0.65, it is possible to obtain an outer ring having a metal flow with a bending ratio substantially the same as that of the raceway surface.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram (1/2) showing an embodiment of a method for manufacturing an outer race for a ball bearing according to the present invention.

FIG. 2 is a manufacturing process diagram (2/2) showing an embodiment of a method for manufacturing an outer race for a ball bearing according to the present invention.

FIG. 3 is a diagram for explaining the critical significance of the optimum range of the upsetting rate η.

FIG. 4 is a cross-sectional view of a workpiece showing a state of metal flow after upsetting in the related art.

[Explanation of symbols]

 1 Cylindrical Steel Billet 2 Metal Flow 4 First Upset Workpiece 5 Second Upset Workpiece 9 Middle Push Section 11 Ring-shaped Workpiece

Claims (1)

[Claims] 1. A columnar steel billet having a first predetermined height H, in which a large number of metal flows are formed in the axial direction of the cross section, is heated to a hot forging zone and then upset to perform a second predetermined height. Producing a first upset workpiece having a height H1 and then
After reversing the upset workpiece, the first upset workpiece is upset to produce a second upset workpiece having a third predetermined height H2, after which the second upset workpiece is manufactured. The center portion of the flat surface of the work piece to be pressed is equally pressed from above and below to form the intermediate press portion, and then the intermediate press portion is hollowed out to form a ring-shaped workpiece, and then the ring-shaped workpiece is formed. Rolling is performed, and the upsetting ratio, which is the ratio of the height reduction amount (H-H2) of the cylindrical steel billet to the first predetermined height H of the cylindrical steel billet, is 0.50 to 0. The method for producing an outer ring for a ball bearing is characterized by setting the number to 65.