US3206828A

US3206828A - Method of making balls

Info

Publication number: US3206828A
Application number: US306907A
Authority: US
Inventors: Kikuchi Takefusa
Original assignee: Taiyu Shoji KK
Current assignee: Taiyu Shoji KK
Priority date: 1963-02-16
Filing date: 1963-09-05
Publication date: 1965-09-21
Anticipated expiration: 1982-09-21

Description

Se t. 21, 1965 TAKEFUSA KlKUCHl 3,206,828

METHOD OF MAKING BALLS 2 Sheets-Sheet 1 Filed Sept. 5, 1963 I JTI.

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METHOD OF MAKING BALLS Filed Sept. 5, 1963 2 Sheets-Sheet 2 n van for TAKEFUSA K/KUCH/ United States Patent 3,206,828 METHOD OF MAKING BALLS Takefusa Kikuchi, Tokyo, Japan, assignor to Taiyu Shojr Kabushiki Kaisha, Chiyoda-ku, Tokyo-t0, Japan Filed Sept. 5, 1963, Ser. No. 306,907 Claims priority, application Japan, Feb. 16, 1963, 38/ 8,018 1 Claim. '(Cl. 29-1484) This invention relates to a manufacturing method of steel balls with a uniform surface fiber structure out of a round bar, by hot rolling.

One of the most important characteristics of steel balls, which are used either for ball bearings or for grinding purposes, is to have uniform mechanical properties not only throughout the ball, but also, all over the surface of the ball.

Such condition is obtained when the structure of material is either completely uniform throughout the ball, or concentrically uniform around the center of the ball like golf balls or baseballs. Steel balls with such structure as above mentioned are the ideal balls.

In the case of balls which have been forged or rolled out of steel bars by conventional methods, such as by drop hammers, upsetters or rolling mills, parallel structural fibers of the bar are cut transversely, and the sections of these fibers come out in the surface of the ball, and the parallel fibers of the original bar remain almost unchanged within the ball, as shown in FIG. 7. This illustrates that the mechanical properties are neither uniform throughout the ball, nor concentrically uniform around the center of the ball. Such balls, when used for ball bearings, will afford uneven rolling resistances, and when used for grinding purposes, will wear unevenly.

This invention eliminates the defectives as above mentioned, by concentrating all the sections of structural fibers to one point on the ball surface, and by covering the ball surface with uniform rolled layer of structural fibers, so that the sections of structural fibers are not exposed on the surface of the ball, and moreover, within the ball the fibers are bent and curved around the ball center, as shown in FIG. 6.

Thus, this invention is a method to roll ideal or nearly ideal balls economically out of a round bar.

In the accompanying drawings, :FIG. 1, FIG. 2, FIG. 3, FIG. 4 and FIG. 5 are the sectional views, showing the progress how a ball is rolled out of a bar, FIG. 6 is the sectional view along the structural fibers within the ball rolled by the invented method, FIG. 7 is the sectional view of a ball, manufactured by the conventional methods, showing the fiber structures within the ball. FIG. 8a, FIG. 8b and FIG. 8c are the sectional side views along Y-Y respectively in FIG. 9a, FIG. 9b and FIG. 90. FIG. 9a, FIG. 9b and FIG. 90 are the sectional views along Z-Z in FIG. 8a, FIG. 8b and FIG. 8c, and FIG. 10 is the sectional perspective view along X--X in FIG. 8b, and show one of the embodiments of the invented method to roll a ball.

As shown in FIG. 8a, FIG. 8b, FIG. 80, FIG. 9a, FIG. 9b, FIG. 90 and FIG. 10 a round bar 5 is inserted transversely between a pair of rolling dies 1. Each of the dies 1 has a set of equally shaped ridges 2 and a groove 3 as shown in FIG. 9b.

The ridge 2 has a uniformly increasing height h as shown in FIG. 8s and FIG. 9s, and a uniformly decreasing top breadth 1 as shown in FIG. 10, and thus forming between them the groove 3 with a uniformly increasing width w and depth h as shown in FIG. 10 and FIG. 8s. The profile of the cross section of the groove 3 is a circular arc, whose radius is equal to the radius of the ball to be rolled, and the cross section of the top of "ice the ridge 2 is a straight line as represented by 2 which is parallel to the center line of the round bar 5, as shown in FIG. 9s.

The ridges 2 as well as the groove 3 start at B, and end at E, as shown in FIG. 8s, where .the profile of the cross section of the groove becomes a complete semi-circle as shown in FIG. 90.

The rolling dies 1 are, as shown in FIG. 8s, arranged face to face but to be shifted longitudinally to the opposite directions as shown by arrows A in FIG. 8s, so that the bottom lines BE of the grooves 3 are kept parallel with each other at a distance equal to the diameter of a ball to be rolled.

In order to roll a ball, a bar 5 is inserted transversely between the 'dies 1, then the dies are shifted longitudinally towards the opposite directions as above described. The dies will then catchthe bar by ridges 2 at the points B where the ridges start as shown in FIG. 8a, and then the ridges and the groove will gradually roll the bar, as shown in FIG. 8b, till at last the dies finish their rolling process at E, where the profiles of the cross section of the groove is a complete semi-circle to produce a spherical ball 6, as shown in FIG. 86.

In the course of rolling, the top surfaces S of the ridges 2, whose cross section are straight lines 2", press the bar radially with pressure p, and the breadth 1 of the surface S gradually decreases to l l l l and so on, as FIG. 1, FIG. 2, FIG. 3 and FIG. 4, till at last becomes zero where the rolling is completed as shown in FIG. 5, FIG. and FIG. 90.

Certain molecules, as represented by a, b, c, d, e, f, g, h and i in FIG. 1, on the surface of the round bar 5, will be removed successively and respectively to a, b, c, d, e, f, g, h and i as shown in FIG. 2, FIG. 3, FIG. 4 and FIG. 5, as rolling proceeds, where the distance L, between the points a and i, as shown in FIG. 1, increases gradually and successively to L L L and L as rolling proceeds, as shown in FIG. 2, FIG. 3, FIG. 4 and FIG. 5.

Moreover, while the bar 5 is rolled from the state as shown in FIG. 1 to the state as shown in FIG. 2, the molecules b, c, d, e, f, g and h are radially removed respectively to b, c, d, e, f and g as shown in FIG. 2, and the portion of structural fiber F between the molecules at and b, as well as the fiber between the molecules h and i are both elongated to finish a portion ab as well as a portion hi of a complete spherical ball.

These portions ab and hi of the ball have been rolled and finished by the rolling groove 3. In the same way, other molecules as c, d, e, f, and g are radially removed successively from their positions as shown in FIG. 3 to their respective positions on the surface of the ball as shown in FIG. 4 and so on, till at last the last molecule e reaches to the axis of the bar, when the rolling process is finished to produce a complete spherical ball 6, as shown in FIG. 5, FIG. 80 and FIG. 90.

Thus, it is clear that the portion ab as well as hi, which has been rolled and finished to compose a portion of spherical surface of the ball as shown in FIG. 2, will not further be rolled again. In the same Way, the portion be and portion gh, which have been finished in the next process, will not further be rolled, and so on, till at last the molecule e reaches the axis of the bar. This process that the ball is rolled by the rolling groove is one of the typical features of this invention.

The ball being rolled like this, it is clear that the whole surface of the ball is covered by fibers F which originally covered the cylindrical surface of the bar 5 and which have been elongated as above described. Similarly all other internal fibers F, having been indirectly rolled by the dies through respective outer layer of fibers, are also bent curved respectively and reversely proportional to an amount to their respective distance from the axis of the bar.

Thus the ball, which has been rolled by the invented method as above described, becomes composed of layers of structural fibers, the outermost of which is a complete spherical layer, which covers the surface of the ball, and the inner fibers F compose successive layers, each of which being nearly concentric and oval, just like layers in onions, as shown in FIG. 6.

The reason why the fiber structure becomes as above described, is to be further explained as follows:

As already described, during the rolling process, the portion of the bar, such as bh in FIG. 2 or d in FIG. 4 is pressed radially with pressure 1 towards the axis of the bar by the surface S of the ridge of uniformly decreasing breadth l, which is a straight line parallel to the axis of the bar 5. Therefore, practically no axial force acts on the said portion of the bar, to pull apart the bar along this portion, and therefore, the rolled ball separates of itself when the rolling process is completed, without being pulled off the bar before the process is completed. Therefore, all fibers concentrate to one point Q on the surface of the ball, as shown in FIG. 6. This is another special feature of the process of this invention.

Thus, the fiber structure of the ball, rolled out of a round bar, by the invented method is very near to an ideal spherical ball.

The roll method as above described, is one of the embodiments of this invention, in which, the rolling ridges and groove are straight and equipped on the surfaces of a pair of plane rolling dies. But actually, these ridges and groove may be equipped, either spirally on the surfaces of a pair of plane circular discs, or helically on the surface of a pair of cylindrical rolling mills.

I claim:

A ball manufacturing method by rolling with a pair of opposed rolling dies, each of which has a set of rolling grooves whose cross section being a circular arc of like radius, said grooves extending longitudinally of said die throughout the length thereof and progressively increasing in depth from one end to the terminal end, the depth of each of the grooves at the terminal end being equal to said radius, said grooves forming ribs therebetween, each of said ribs decreasing in width from one end to said terminal end where it forms a sharp pointed edge, the grooves in said opposed dies being reversely arranged, inserting between said dies a cylindrical bar to be rolled into balls, shifting said dies toward opposite directions with rolling pressure acting radially on the bar, deforming said bar gradually toward the coacting terminal ends of said dies and ribs thereof to gradually form the balls and separate them in finished form by the opposed sharp pointed edges at the ends of said ribs.

References Cited by the Examiner UNITED STATES PATENTS 2,700,908 2/55 Bockting 7293 WHITMORE A. WILTZ, Primary Examiner.

THOMAS H. EAGER, Examiner.