JPH03204412A - Manufacture of two-piece bearing - Google Patents

Abstract

PURPOSE:To reduce a margin for grinding so as to decrease working manhours by applying heat treatment to a ring type bearing intermediate body, deforming it into an ellipse in tempering process, and cutting it by means of a cutter having a width of a difference between a major axis and a minor axis so as to obtain a pair of semi-circular bearing rings. CONSTITUTION:A ring type bearing intermediate body 1 is manufactured by casting, and a thermal treatment for hardening the surface is applied to the body 1, followed by secondary quenching at a predetermined temperature. In a tempering process, the intermediate body 1 is deformed into an ellipse having a major axis D+T and a minor axis D from the inside at 90 deg. with respect to a position cut by a cutter by means of a correction jig. The intermediate body 1 is cut by a cutter 2 having a width T, to be divided into a pair of semi- circular bearing ring intermediate bodies 1a', 1b', thus obtaining two-piece bearing rings 1a, 1b with application of grinding work. With this method of manufacture, a margin for grinding as well as working manhours can be reduced. Particularly, the margin, i.e., carburization depth, can be reduced, and therefore, manhours for heat treatment can be decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a two-part bearing,
Specifically, the present invention relates to a method for manufacturing a two-part raceway ring used as a bearing device for a crankshaft of an internal combustion engine or an external combustion engine, a connecting rod of a rolling mill, or the like.

[Conventional technology]

A natural side method is known as a method for manufacturing two-piece bearings. As shown in Fig. 2, this method utilizes the crack sensitivity of hardened steel to manufacture bearing rings (1a) and (1b), and the outer circumferential surface of the ring-shaped bearing intermediate structure (1) Form grooves (3) (3) with a cutter (2) in the grooves (3) (3).
A crack (5) is generated in the ring-shaped bearing intermediate structure (1) by driving li' (4) into the ring-shaped bearing intermediate structure (1), and a set of two semicircular bearing rings (la) (lb) is manufactured. It is.

Since the natural side method uses the crack sensitivity of hardened steel as a dividing means, it may not be usable depending on the material and shape of the two-piece bearing.

For example, when the bearing ring (la) (lb) is manufactured from carburized steel, it is difficult to adopt the natural side method because the crack sensitivity value is low;
) is thick, the raceway ring (la) (lb
) is not hardened to the inside, so the crack sensitivity value is low, making it difficult to use the natural side method. Furthermore, the bearing ring (la
) or (1b), if the difference in wall thickness is large, for example, in a ball bearing (6) as shown in Fig. 3, the inner ring (7) has wall thicknesses T If there is a large difference, it is difficult to use the natural side method because the crack cannot be expected to extend in the axial direction.

[Problem to be solved by the invention] The above-mentioned restrictions due to material and shape when manufacturing a two-split bearing by the natural side method are removed (therefore, the turning process and heat treatment to create a half-split state as shown in Fig. 4) are removed. A bearing manufacturing method that combines processes is used.

However, with this method, after turning the ring-shaped bearing intermediate structure into half halves, each of the two divided bearing rings (
Since the heat treatment is applied to the bearing rings (la) (lb), large thermal deformation occurs in the bearing rings (la) (lb) during the heat treatment, as shown by the diagonal arrows and the two-dot chain line in FIG.

As a result, the machining allowance for finish grinding becomes larger compared to the case where the bearing intermediate structure is heat-treated in its ring-shaped form.

In particular, when the bearing rings (la) (1, b) are made of carburized steel, the thermal deformation described above is significant, making it difficult to secure the required depth of the hardened layer (8). Become.

[Means to solve the problem]

As a means for solving the above-mentioned problems, the present invention includes a step of heat-treating a ring-shaped bearing intermediate structure formed by forging, and a tempering process of the ring-shaped bearing intermediate structure, in which the ring-shaped bearing intermediate structure is formed into an elliptical shape with a major axis of T and a minor axis. an ellipse correction process in which the bearing intermediate structure is transformed into a bearing intermediate structure (here, T is the blade width of the cutter), and the bearing intermediate structure is cut along the short axis with a cutter having a blade width dimension of T to form a semicircular cross section. The present invention provides a method for manufacturing a two-piece bearing, which comprises a step of forming a set of two raceway rings with a shape, and a step of grinding the raceway rings cut into sets of two.

: Effect] Before cutting the ring-shaped bearing intermediate structure into a set of two bearing rings each having a semicircular cross-sectional shape using a cutter, an ellipse correction jig is used during tempering of the ring-shaped bearing intermediate structure. By pulling it out, it is deformed into an elliptical shape by the length of the cutter's blade width in the major diameter direction. After this, the bearing intermediate structure deformed into an elliptical shape is cut along the short axis with a cutter having the blade width described above, so that when the cut ends are brought together, the cross-sectional shape becomes a perfect circle. A set of semicircular bearing rings is manufactured.

(Example) FIG. 1A is a process diagram for explaining the method of the present invention, and FIG. 1B is a front view of a bearing intermediate structure and a bearing ring intermediate structure showing the cutting process.

In the following description, the same constituent members as those in FIGS. 2 to 5 showing the prior art are indicated by the same reference numerals, and explanations of overlapping matters will be omitted.

Hereinafter, two-split bearing rings (la) (lb) used in bearing devices for rolling mill connecting rods (not shown)
) from carburized steel.

A ring-shaped bearing intermediate structure (1) having an average inner diameter of about 770 mm, an average outer diameter of 1070 mm, and a width of about 300 m is manufactured by forging from a carburized steel material in accordance with the diameter of the connecting rod of 770+ms. To explain more precisely, the maximum inner diameter of this bearing intermediate structure (1) is larger than the diameter of the connecting rod (770 mm) in preparation for cutting by the cutter (2) described later.
2) The blade width dimension T (for example, 3 mm) is set to a larger diameter. After the ring-shaped bearing intermediate structure (1) is subjected to surface hardening heat treatment (carburizing process), this bearing intermediate structure ( 1) is heated in the ring shape to a predetermined temperature to perform secondary quenching.

Next, during the tempering process, the ring-shaped bearing intermediate structure (1)
Next, the ring-shaped bearing intermediate structure (1) is deformed into an elliptical shape using a correction jig from the inside at a position 90° from the cut position of the cutter (2) (FIGS. 1C and D). Thereafter, by cutting the ring-shaped bearing intermediate structure (1) in the short diameter direction with a canter (2) having a width of 11, a set of two bearing ring intermediate structures (la ') (lb') is formed. Finally, the raceway ring intermediate structure (la') (
Finish grinding is applied to the surface of lb'). This creates a two-part raceway ring (la) with a perfectly circular cross-sectional shape.
) (lb) is produced as the final product.

In the above example, a correction jig is used for the ring-shaped bearing intermediate structure (1) during tempering to deform it into an elliptical shape. A method of deforming using a correction jig can also be adopted.

[Effects of the Invention] Since the bearing intermediate structure is heat-treated while still in the ring shape, deformation during the heat treatment process is small, and the machining allowance for finish grinding can be reduced accordingly. Therefore, it is possible to reduce the number of processing steps. In particular, when manufacturing raceway rings from carburized steel, it is not necessary to allow for a large carburizing depth as a machining allowance due to thermal deformation, which greatly reduces the number of heat treatment steps.

[Brief explanation of drawings]

FIG. 1A is a process diagram explaining the method of the present invention, FIG. 1B is a front view of a bearing intermediate structure and a drive wheel intermediate structure showing the cutting process, FIG. 1C is a process diagram explaining the ellipse correction process, The first diagram is a front view showing the ellipse correction process, the second diagram is an explanatory diagram of the natural side method, the third diagram is a vertical cross-sectional view of the inner ring of a ball bearing, the fourth diagram is a process diagram of the conventional method, and the fifth diagram is It is a top view explaining the thermal deformation form of the bearing ring when using the conventional method. (1) - Ring-shaped bearing intermediate structure, (la) (1bL-One-ring, (la') (lb")-Rearing ring intermediate structure, (2)
- Cutter, (T) - Cutter blade width. Figure 1 (AI Melting 5゛Figure 1 Doctor C1 Figure 2/

Claims (1)

[Claims] (1) A process of heat-treating the ring-shaped bearing intermediate structure formed by forging, and during tempering of the ring-shaped bearing intermediate structure, the major diameter D
an ellipse correction step in which the bearing intermediate structure is transformed into an elliptical bearing intermediate structure with a width of +T and a minor axis D (here, T is the blade width of the cutter); Manufacture of a two-piece type bearing, which includes a step of cutting and forming a set of two bearing rings with a semicircular cross-sectional shape, and a grinding process of the cut rings into two sets. Method.